[PATCH 01/20] perf: Start the massive restructuring

[Borislav Petkov]

From: Borislav Petkov <borislav.petkov@xxxxxxx>

mv kernel/perf_event.c -> kernel/events/core.c. From there, all other
sensible splitting can happen.

Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
---
 kernel/Makefile        |    5 +-
 kernel/events/Makefile |    5 +
 kernel/events/core.c   | 5895 ++++++++++++++++++++++++++++++++++++++++++++++++
 kernel/perf_event.c    | 5895 ------------------------------------------------
 4 files changed, 5904 insertions(+), 5896 deletions(-)
 create mode 100644 kernel/events/Makefile
 create mode 100644 kernel/events/core.c
 delete mode 100644 kernel/perf_event.c

diff --git a/kernel/Makefile b/kernel/Makefile
index 0b72d1a..5830059 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -100,7 +100,10 @@ obj-$(CONFIG_TRACING) += trace/
 obj-$(CONFIG_X86_DS) += trace/
 obj-$(CONFIG_RING_BUFFER) += trace/
 obj-$(CONFIG_SMP) += sched_cpupri.o
-obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+
+# obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_PERF_EVENTS) += events/
+
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
diff --git a/kernel/events/Makefile b/kernel/events/Makefile
new file mode 100644
index 0000000..5445cbf
--- /dev/null
+++ b/kernel/events/Makefile
@@ -0,0 +1,5 @@
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_perf_event.o = -pg
+endif
+
+obj-y += core.o
diff --git a/kernel/events/core.c b/kernel/events/core.c
new file mode 100644
index 0000000..b98bed3
--- /dev/null
+++ b/kernel/events/core.c
@@ -0,0 +1,5895 @@
+/*
+ * Performance events core code:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@xxxxxxxxxxxxx>
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@xxxxxxxxxx>
+ *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@xxxxxxxxxxx>
+ *
+ * For licensing details see kernel-base/COPYING
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+#include <linux/sysfs.h>
+#include <linux/dcache.h>
+#include <linux/percpu.h>
+#include <linux/ptrace.h>
+#include <linux/vmstat.h>
+#include <linux/vmalloc.h>
+#include <linux/hardirq.h>
+#include <linux/rculist.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
+
+#include <asm/irq_regs.h>
+
+/*
+ * Each CPU has a list of per CPU events:
+ */
+static DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
+
+int perf_max_events __read_mostly = 1;
+static int perf_reserved_percpu __read_mostly;
+static int perf_overcommit __read_mostly = 1;
+
+static atomic_t nr_events __read_mostly;
+static atomic_t nr_mmap_events __read_mostly;
+static atomic_t nr_comm_events __read_mostly;
+static atomic_t nr_task_events __read_mostly;
+
+/*
+ * perf event paranoia level:
+ *  -1 - not paranoid at all
+ *   0 - disallow raw tracepoint access for unpriv
+ *   1 - disallow cpu events for unpriv
+ *   2 - disallow kernel profiling for unpriv
+ */
+int sysctl_perf_event_paranoid __read_mostly = 1;
+
+int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
+
+/*
+ * max perf event sample rate
+ */
+int sysctl_perf_event_sample_rate __read_mostly = 100000;
+
+static atomic64_t perf_event_id;
+
+/*
+ * Lock for (sysadmin-configurable) event reservations:
+ */
+static DEFINE_SPINLOCK(perf_resource_lock);
+
+/*
+ * Architecture provided APIs - weak aliases:
+ */
+extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
+{
+	return NULL;
+}
+
+void __weak hw_perf_disable(void)		{ barrier(); }
+void __weak hw_perf_enable(void)		{ barrier(); }
+
+void __weak perf_event_print_debug(void)	{ }
+
+static DEFINE_PER_CPU(int, perf_disable_count);
+
+void perf_disable(void)
+{
+	if (!__get_cpu_var(perf_disable_count)++)
+		hw_perf_disable();
+}
+
+void perf_enable(void)
+{
+	if (!--__get_cpu_var(perf_disable_count))
+		hw_perf_enable();
+}
+
+static void get_ctx(struct perf_event_context *ctx)
+{
+	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
+}
+
+static void free_ctx(struct rcu_head *head)
+{
+	struct perf_event_context *ctx;
+
+	ctx = container_of(head, struct perf_event_context, rcu_head);
+	kfree(ctx);
+}
+
+static void put_ctx(struct perf_event_context *ctx)
+{
+	if (atomic_dec_and_test(&ctx->refcount)) {
+		if (ctx->parent_ctx)
+			put_ctx(ctx->parent_ctx);
+		if (ctx->task)
+			put_task_struct(ctx->task);
+		call_rcu(&ctx->rcu_head, free_ctx);
+	}
+}
+
+static void unclone_ctx(struct perf_event_context *ctx)
+{
+	if (ctx->parent_ctx) {
+		put_ctx(ctx->parent_ctx);
+		ctx->parent_ctx = NULL;
+	}
+}
+
+/*
+ * If we inherit events we want to return the parent event id
+ * to userspace.
+ */
+static u64 primary_event_id(struct perf_event *event)
+{
+	u64 id = event->id;
+
+	if (event->parent)
+		id = event->parent->id;
+
+	return id;
+}
+
+/*
+ * Get the perf_event_context for a task and lock it.
+ * This has to cope with with the fact that until it is locked,
+ * the context could get moved to another task.
+ */
+static struct perf_event_context *
+perf_lock_task_context(struct task_struct *task, unsigned long *flags)
+{
+	struct perf_event_context *ctx;
+
+	rcu_read_lock();
+ retry:
+	ctx = rcu_dereference(task->perf_event_ctxp);
+	if (ctx) {
+		/*
+		 * If this context is a clone of another, it might
+		 * get swapped for another underneath us by
+		 * perf_event_task_sched_out, though the
+		 * rcu_read_lock() protects us from any context
+		 * getting freed.  Lock the context and check if it
+		 * got swapped before we could get the lock, and retry
+		 * if so.  If we locked the right context, then it
+		 * can't get swapped on us any more.
+		 */
+		raw_spin_lock_irqsave(&ctx->lock, *flags);
+		if (ctx != rcu_dereference(task->perf_event_ctxp)) {
+			raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+			goto retry;
+		}
+
+		if (!atomic_inc_not_zero(&ctx->refcount)) {
+			raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+			ctx = NULL;
+		}
+	}
+	rcu_read_unlock();
+	return ctx;
+}
+
+/*
+ * Get the context for a task and increment its pin_count so it
+ * can't get swapped to another task.  This also increments its
+ * reference count so that the context can't get freed.
+ */
+static struct perf_event_context *perf_pin_task_context(struct task_struct *task)
+{
+	struct perf_event_context *ctx;
+	unsigned long flags;
+
+	ctx = perf_lock_task_context(task, &flags);
+	if (ctx) {
+		++ctx->pin_count;
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+	return ctx;
+}
+
+static void perf_unpin_context(struct perf_event_context *ctx)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ctx->lock, flags);
+	--ctx->pin_count;
+	raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	put_ctx(ctx);
+}
+
+static inline u64 perf_clock(void)
+{
+	return local_clock();
+}
+
+/*
+ * Update the record of the current time in a context.
+ */
+static void update_context_time(struct perf_event_context *ctx)
+{
+	u64 now = perf_clock();
+
+	ctx->time += now - ctx->timestamp;
+	ctx->timestamp = now;
+}
+
+/*
+ * Update the total_time_enabled and total_time_running fields for a event.
+ */
+static void update_event_times(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	u64 run_end;
+
+	if (event->state < PERF_EVENT_STATE_INACTIVE ||
+	    event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
+		return;
+
+	if (ctx->is_active)
+		run_end = ctx->time;
+	else
+		run_end = event->tstamp_stopped;
+
+	event->total_time_enabled = run_end - event->tstamp_enabled;
+
+	if (event->state == PERF_EVENT_STATE_INACTIVE)
+		run_end = event->tstamp_stopped;
+	else
+		run_end = ctx->time;
+
+	event->total_time_running = run_end - event->tstamp_running;
+}
+
+/*
+ * Update total_time_enabled and total_time_running for all events in a group.
+ */
+static void update_group_times(struct perf_event *leader)
+{
+	struct perf_event *event;
+
+	update_event_times(leader);
+	list_for_each_entry(event, &leader->sibling_list, group_entry)
+		update_event_times(event);
+}
+
+static struct list_head *
+ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
+{
+	if (event->attr.pinned)
+		return &ctx->pinned_groups;
+	else
+		return &ctx->flexible_groups;
+}
+
+/*
+ * Add a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_add_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
+	event->attach_state |= PERF_ATTACH_CONTEXT;
+
+	/*
+	 * If we're a stand alone event or group leader, we go to the context
+	 * list, group events are kept attached to the group so that
+	 * perf_group_detach can, at all times, locate all siblings.
+	 */
+	if (event->group_leader == event) {
+		struct list_head *list;
+
+		if (is_software_event(event))
+			event->group_flags |= PERF_GROUP_SOFTWARE;
+
+		list = ctx_group_list(event, ctx);
+		list_add_tail(&event->group_entry, list);
+	}
+
+	list_add_rcu(&event->event_entry, &ctx->event_list);
+	ctx->nr_events++;
+	if (event->attr.inherit_stat)
+		ctx->nr_stat++;
+}
+
+static void perf_group_attach(struct perf_event *event)
+{
+	struct perf_event *group_leader = event->group_leader;
+
+	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_GROUP);
+	event->attach_state |= PERF_ATTACH_GROUP;
+
+	if (group_leader == event)
+		return;
+
+	if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
+			!is_software_event(event))
+		group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
+
+	list_add_tail(&event->group_entry, &group_leader->sibling_list);
+	group_leader->nr_siblings++;
+}
+
+/*
+ * Remove a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_del_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+	/*
+	 * We can have double detach due to exit/hot-unplug + close.
+	 */
+	if (!(event->attach_state & PERF_ATTACH_CONTEXT))
+		return;
+
+	event->attach_state &= ~PERF_ATTACH_CONTEXT;
+
+	ctx->nr_events--;
+	if (event->attr.inherit_stat)
+		ctx->nr_stat--;
+
+	list_del_rcu(&event->event_entry);
+
+	if (event->group_leader == event)
+		list_del_init(&event->group_entry);
+
+	update_group_times(event);
+
+	/*
+	 * If event was in error state, then keep it
+	 * that way, otherwise bogus counts will be
+	 * returned on read(). The only way to get out
+	 * of error state is by explicit re-enabling
+	 * of the event
+	 */
+	if (event->state > PERF_EVENT_STATE_OFF)
+		event->state = PERF_EVENT_STATE_OFF;
+}
+
+static void perf_group_detach(struct perf_event *event)
+{
+	struct perf_event *sibling, *tmp;
+	struct list_head *list = NULL;
+
+	/*
+	 * We can have double detach due to exit/hot-unplug + close.
+	 */
+	if (!(event->attach_state & PERF_ATTACH_GROUP))
+		return;
+
+	event->attach_state &= ~PERF_ATTACH_GROUP;
+
+	/*
+	 * If this is a sibling, remove it from its group.
+	 */
+	if (event->group_leader != event) {
+		list_del_init(&event->group_entry);
+		event->group_leader->nr_siblings--;
+		return;
+	}
+
+	if (!list_empty(&event->group_entry))
+		list = &event->group_entry;
+
+	/*
+	 * If this was a group event with sibling events then
+	 * upgrade the siblings to singleton events by adding them
+	 * to whatever list we are on.
+	 */
+	list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
+		if (list)
+			list_move_tail(&sibling->group_entry, list);
+		sibling->group_leader = sibling;
+
+		/* Inherit group flags from the previous leader */
+		sibling->group_flags = event->group_flags;
+	}
+}
+
+static inline int
+event_filter_match(struct perf_event *event)
+{
+	return event->cpu == -1 || event->cpu == smp_processor_id();
+}
+
+static void
+event_sched_out(struct perf_event *event,
+		  struct perf_cpu_context *cpuctx,
+		  struct perf_event_context *ctx)
+{
+	u64 delta;
+	/*
+	 * An event which could not be activated because of
+	 * filter mismatch still needs to have its timings
+	 * maintained, otherwise bogus information is return
+	 * via read() for time_enabled, time_running:
+	 */
+	if (event->state == PERF_EVENT_STATE_INACTIVE
+	    && !event_filter_match(event)) {
+		delta = ctx->time - event->tstamp_stopped;
+		event->tstamp_running += delta;
+		event->tstamp_stopped = ctx->time;
+	}
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return;
+
+	event->state = PERF_EVENT_STATE_INACTIVE;
+	if (event->pending_disable) {
+		event->pending_disable = 0;
+		event->state = PERF_EVENT_STATE_OFF;
+	}
+	event->tstamp_stopped = ctx->time;
+	event->pmu->disable(event);
+	event->oncpu = -1;
+
+	if (!is_software_event(event))
+		cpuctx->active_oncpu--;
+	ctx->nr_active--;
+	if (event->attr.exclusive || !cpuctx->active_oncpu)
+		cpuctx->exclusive = 0;
+}
+
+static void
+group_sched_out(struct perf_event *group_event,
+		struct perf_cpu_context *cpuctx,
+		struct perf_event_context *ctx)
+{
+	struct perf_event *event;
+	int state = group_event->state;
+
+	event_sched_out(group_event, cpuctx, ctx);
+
+	/*
+	 * Schedule out siblings (if any):
+	 */
+	list_for_each_entry(event, &group_event->sibling_list, group_entry)
+		event_sched_out(event, cpuctx, ctx);
+
+	if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive)
+		cpuctx->exclusive = 0;
+}
+
+/*
+ * Cross CPU call to remove a performance event
+ *
+ * We disable the event on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static void __perf_event_remove_from_context(void *info)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event *event = info;
+	struct perf_event_context *ctx = event->ctx;
+
+	/*
+	 * If this is a task context, we need to check whether it is
+	 * the current task context of this cpu. If not it has been
+	 * scheduled out before the smp call arrived.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx)
+		return;
+
+	raw_spin_lock(&ctx->lock);
+	/*
+	 * Protect the list operation against NMI by disabling the
+	 * events on a global level.
+	 */
+	perf_disable();
+
+	event_sched_out(event, cpuctx, ctx);
+
+	list_del_event(event, ctx);
+
+	if (!ctx->task) {
+		/*
+		 * Allow more per task events with respect to the
+		 * reservation:
+		 */
+		cpuctx->max_pertask =
+			min(perf_max_events - ctx->nr_events,
+			    perf_max_events - perf_reserved_percpu);
+	}
+
+	perf_enable();
+	raw_spin_unlock(&ctx->lock);
+}
+
+
+/*
+ * Remove the event from a task's (or a CPU's) list of events.
+ *
+ * Must be called with ctx->mutex held.
+ *
+ * CPU events are removed with a smp call. For task events we only
+ * call when the task is on a CPU.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This is OK when called from perf_release since
+ * that only calls us on the top-level context, which can't be a clone.
+ * When called from perf_event_exit_task, it's OK because the
+ * context has been detached from its task.
+ */
+static void perf_event_remove_from_context(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct task_struct *task = ctx->task;
+
+	if (!task) {
+		/*
+		 * Per cpu events are removed via an smp call and
+		 * the removal is always successful.
+		 */
+		smp_call_function_single(event->cpu,
+					 __perf_event_remove_from_context,
+					 event, 1);
+		return;
+	}
+
+retry:
+	task_oncpu_function_call(task, __perf_event_remove_from_context,
+				 event);
+
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * If the context is active we need to retry the smp call.
+	 */
+	if (ctx->nr_active && !list_empty(&event->group_entry)) {
+		raw_spin_unlock_irq(&ctx->lock);
+		goto retry;
+	}
+
+	/*
+	 * The lock prevents that this context is scheduled in so we
+	 * can remove the event safely, if the call above did not
+	 * succeed.
+	 */
+	if (!list_empty(&event->group_entry))
+		list_del_event(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to disable a performance event
+ */
+static void __perf_event_disable(void *info)
+{
+	struct perf_event *event = info;
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = event->ctx;
+
+	/*
+	 * If this is a per-task event, need to check whether this
+	 * event's task is the current task on this cpu.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx)
+		return;
+
+	raw_spin_lock(&ctx->lock);
+
+	/*
+	 * If the event is on, turn it off.
+	 * If it is in error state, leave it in error state.
+	 */
+	if (event->state >= PERF_EVENT_STATE_INACTIVE) {
+		update_context_time(ctx);
+		update_group_times(event);
+		if (event == event->group_leader)
+			group_sched_out(event, cpuctx, ctx);
+		else
+			event_sched_out(event, cpuctx, ctx);
+		event->state = PERF_EVENT_STATE_OFF;
+	}
+
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Disable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisifed when called through
+ * perf_event_for_each_child or perf_event_for_each because they
+ * hold the top-level event's child_mutex, so any descendant that
+ * goes to exit will block in sync_child_event.
+ * When called from perf_pending_event it's OK because event->ctx
+ * is the current context on this CPU and preemption is disabled,
+ * hence we can't get into perf_event_task_sched_out for this context.
+ */
+void perf_event_disable(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct task_struct *task = ctx->task;
+
+	if (!task) {
+		/*
+		 * Disable the event on the cpu that it's on
+		 */
+		smp_call_function_single(event->cpu, __perf_event_disable,
+					 event, 1);
+		return;
+	}
+
+ retry:
+	task_oncpu_function_call(task, __perf_event_disable, event);
+
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * If the event is still active, we need to retry the cross-call.
+	 */
+	if (event->state == PERF_EVENT_STATE_ACTIVE) {
+		raw_spin_unlock_irq(&ctx->lock);
+		goto retry;
+	}
+
+	/*
+	 * Since we have the lock this context can't be scheduled
+	 * in, so we can change the state safely.
+	 */
+	if (event->state == PERF_EVENT_STATE_INACTIVE) {
+		update_group_times(event);
+		event->state = PERF_EVENT_STATE_OFF;
+	}
+
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+static int
+event_sched_in(struct perf_event *event,
+		 struct perf_cpu_context *cpuctx,
+		 struct perf_event_context *ctx)
+{
+	if (event->state <= PERF_EVENT_STATE_OFF)
+		return 0;
+
+	event->state = PERF_EVENT_STATE_ACTIVE;
+	event->oncpu = smp_processor_id();
+	/*
+	 * The new state must be visible before we turn it on in the hardware:
+	 */
+	smp_wmb();
+
+	if (event->pmu->enable(event)) {
+		event->state = PERF_EVENT_STATE_INACTIVE;
+		event->oncpu = -1;
+		return -EAGAIN;
+	}
+
+	event->tstamp_running += ctx->time - event->tstamp_stopped;
+
+	if (!is_software_event(event))
+		cpuctx->active_oncpu++;
+	ctx->nr_active++;
+
+	if (event->attr.exclusive)
+		cpuctx->exclusive = 1;
+
+	return 0;
+}
+
+static int
+group_sched_in(struct perf_event *group_event,
+	       struct perf_cpu_context *cpuctx,
+	       struct perf_event_context *ctx)
+{
+	struct perf_event *event, *partial_group = NULL;
+	const struct pmu *pmu = group_event->pmu;
+	bool txn = false;
+
+	if (group_event->state == PERF_EVENT_STATE_OFF)
+		return 0;
+
+	/* Check if group transaction availabe */
+	if (pmu->start_txn)
+		txn = true;
+
+	if (txn)
+		pmu->start_txn(pmu);
+
+	if (event_sched_in(group_event, cpuctx, ctx)) {
+		if (txn)
+			pmu->cancel_txn(pmu);
+		return -EAGAIN;
+	}
+
+	/*
+	 * Schedule in siblings as one group (if any):
+	 */
+	list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+		if (event_sched_in(event, cpuctx, ctx)) {
+			partial_group = event;
+			goto group_error;
+		}
+	}
+
+	if (!txn || !pmu->commit_txn(pmu))
+		return 0;
+
+group_error:
+	/*
+	 * Groups can be scheduled in as one unit only, so undo any
+	 * partial group before returning:
+	 */
+	list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+		if (event == partial_group)
+			break;
+		event_sched_out(event, cpuctx, ctx);
+	}
+	event_sched_out(group_event, cpuctx, ctx);
+
+	if (txn)
+		pmu->cancel_txn(pmu);
+
+	return -EAGAIN;
+}
+
+/*
+ * Work out whether we can put this event group on the CPU now.
+ */
+static int group_can_go_on(struct perf_event *event,
+			   struct perf_cpu_context *cpuctx,
+			   int can_add_hw)
+{
+	/*
+	 * Groups consisting entirely of software events can always go on.
+	 */
+	if (event->group_flags & PERF_GROUP_SOFTWARE)
+		return 1;
+	/*
+	 * If an exclusive group is already on, no other hardware
+	 * events can go on.
+	 */
+	if (cpuctx->exclusive)
+		return 0;
+	/*
+	 * If this group is exclusive and there are already
+	 * events on the CPU, it can't go on.
+	 */
+	if (event->attr.exclusive && cpuctx->active_oncpu)
+		return 0;
+	/*
+	 * Otherwise, try to add it if all previous groups were able
+	 * to go on.
+	 */
+	return can_add_hw;
+}
+
+static void add_event_to_ctx(struct perf_event *event,
+			       struct perf_event_context *ctx)
+{
+	list_add_event(event, ctx);
+	perf_group_attach(event);
+	event->tstamp_enabled = ctx->time;
+	event->tstamp_running = ctx->time;
+	event->tstamp_stopped = ctx->time;
+}
+
+/*
+ * Cross CPU call to install and enable a performance event
+ *
+ * Must be called with ctx->mutex held
+ */
+static void __perf_install_in_context(void *info)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event *event = info;
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_event *leader = event->group_leader;
+	int err;
+
+	/*
+	 * If this is a task context, we need to check whether it is
+	 * the current task context of this cpu. If not it has been
+	 * scheduled out before the smp call arrived.
+	 * Or possibly this is the right context but it isn't
+	 * on this cpu because it had no events.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx) {
+		if (cpuctx->task_ctx || ctx->task != current)
+			return;
+		cpuctx->task_ctx = ctx;
+	}
+
+	raw_spin_lock(&ctx->lock);
+	ctx->is_active = 1;
+	update_context_time(ctx);
+
+	/*
+	 * Protect the list operation against NMI by disabling the
+	 * events on a global level. NOP for non NMI based events.
+	 */
+	perf_disable();
+
+	add_event_to_ctx(event, ctx);
+
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
+	/*
+	 * Don't put the event on if it is disabled or if
+	 * it is in a group and the group isn't on.
+	 */
+	if (event->state != PERF_EVENT_STATE_INACTIVE ||
+	    (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
+		goto unlock;
+
+	/*
+	 * An exclusive event can't go on if there are already active
+	 * hardware events, and no hardware event can go on if there
+	 * is already an exclusive event on.
+	 */
+	if (!group_can_go_on(event, cpuctx, 1))
+		err = -EEXIST;
+	else
+		err = event_sched_in(event, cpuctx, ctx);
+
+	if (err) {
+		/*
+		 * This event couldn't go on.  If it is in a group
+		 * then we have to pull the whole group off.
+		 * If the event group is pinned then put it in error state.
+		 */
+		if (leader != event)
+			group_sched_out(leader, cpuctx, ctx);
+		if (leader->attr.pinned) {
+			update_group_times(leader);
+			leader->state = PERF_EVENT_STATE_ERROR;
+		}
+	}
+
+	if (!err && !ctx->task && cpuctx->max_pertask)
+		cpuctx->max_pertask--;
+
+ unlock:
+	perf_enable();
+
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Attach a performance event to a context
+ *
+ * First we add the event to the list with the hardware enable bit
+ * in event->hw_config cleared.
+ *
+ * If the event is attached to a task which is on a CPU we use a smp
+ * call to enable it in the task context. The task might have been
+ * scheduled away, but we check this in the smp call again.
+ *
+ * Must be called with ctx->mutex held.
+ */
+static void
+perf_install_in_context(struct perf_event_context *ctx,
+			struct perf_event *event,
+			int cpu)
+{
+	struct task_struct *task = ctx->task;
+
+	if (!task) {
+		/*
+		 * Per cpu events are installed via an smp call and
+		 * the install is always successful.
+		 */
+		smp_call_function_single(cpu, __perf_install_in_context,
+					 event, 1);
+		return;
+	}
+
+retry:
+	task_oncpu_function_call(task, __perf_install_in_context,
+				 event);
+
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * we need to retry the smp call.
+	 */
+	if (ctx->is_active && list_empty(&event->group_entry)) {
+		raw_spin_unlock_irq(&ctx->lock);
+		goto retry;
+	}
+
+	/*
+	 * The lock prevents that this context is scheduled in so we
+	 * can add the event safely, if it the call above did not
+	 * succeed.
+	 */
+	if (list_empty(&event->group_entry))
+		add_event_to_ctx(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Put a event into inactive state and update time fields.
+ * Enabling the leader of a group effectively enables all
+ * the group members that aren't explicitly disabled, so we
+ * have to update their ->tstamp_enabled also.
+ * Note: this works for group members as well as group leaders
+ * since the non-leader members' sibling_lists will be empty.
+ */
+static void __perf_event_mark_enabled(struct perf_event *event,
+					struct perf_event_context *ctx)
+{
+	struct perf_event *sub;
+
+	event->state = PERF_EVENT_STATE_INACTIVE;
+	event->tstamp_enabled = ctx->time - event->total_time_enabled;
+	list_for_each_entry(sub, &event->sibling_list, group_entry)
+		if (sub->state >= PERF_EVENT_STATE_INACTIVE)
+			sub->tstamp_enabled =
+				ctx->time - sub->total_time_enabled;
+}
+
+/*
+ * Cross CPU call to enable a performance event
+ */
+static void __perf_event_enable(void *info)
+{
+	struct perf_event *event = info;
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_event *leader = event->group_leader;
+	int err;
+
+	/*
+	 * If this is a per-task event, need to check whether this
+	 * event's task is the current task on this cpu.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx) {
+		if (cpuctx->task_ctx || ctx->task != current)
+			return;
+		cpuctx->task_ctx = ctx;
+	}
+
+	raw_spin_lock(&ctx->lock);
+	ctx->is_active = 1;
+	update_context_time(ctx);
+
+	if (event->state >= PERF_EVENT_STATE_INACTIVE)
+		goto unlock;
+	__perf_event_mark_enabled(event, ctx);
+
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
+	/*
+	 * If the event is in a group and isn't the group leader,
+	 * then don't put it on unless the group is on.
+	 */
+	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
+		goto unlock;
+
+	if (!group_can_go_on(event, cpuctx, 1)) {
+		err = -EEXIST;
+	} else {
+		perf_disable();
+		if (event == leader)
+			err = group_sched_in(event, cpuctx, ctx);
+		else
+			err = event_sched_in(event, cpuctx, ctx);
+		perf_enable();
+	}
+
+	if (err) {
+		/*
+		 * If this event can't go on and it's part of a
+		 * group, then the whole group has to come off.
+		 */
+		if (leader != event)
+			group_sched_out(leader, cpuctx, ctx);
+		if (leader->attr.pinned) {
+			update_group_times(leader);
+			leader->state = PERF_EVENT_STATE_ERROR;
+		}
+	}
+
+ unlock:
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Enable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisfied when called through
+ * perf_event_for_each_child or perf_event_for_each as described
+ * for perf_event_disable.
+ */
+void perf_event_enable(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct task_struct *task = ctx->task;
+
+	if (!task) {
+		/*
+		 * Enable the event on the cpu that it's on
+		 */
+		smp_call_function_single(event->cpu, __perf_event_enable,
+					 event, 1);
+		return;
+	}
+
+	raw_spin_lock_irq(&ctx->lock);
+	if (event->state >= PERF_EVENT_STATE_INACTIVE)
+		goto out;
+
+	/*
+	 * If the event is in error state, clear that first.
+	 * That way, if we see the event in error state below, we
+	 * know that it has gone back into error state, as distinct
+	 * from the task having been scheduled away before the
+	 * cross-call arrived.
+	 */
+	if (event->state == PERF_EVENT_STATE_ERROR)
+		event->state = PERF_EVENT_STATE_OFF;
+
+ retry:
+	raw_spin_unlock_irq(&ctx->lock);
+	task_oncpu_function_call(task, __perf_event_enable, event);
+
+	raw_spin_lock_irq(&ctx->lock);
+
+	/*
+	 * If the context is active and the event is still off,
+	 * we need to retry the cross-call.
+	 */
+	if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF)
+		goto retry;
+
+	/*
+	 * Since we have the lock this context can't be scheduled
+	 * in, so we can change the state safely.
+	 */
+	if (event->state == PERF_EVENT_STATE_OFF)
+		__perf_event_mark_enabled(event, ctx);
+
+ out:
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+static int perf_event_refresh(struct perf_event *event, int refresh)
+{
+	/*
+	 * not supported on inherited events
+	 */
+	if (event->attr.inherit)
+		return -EINVAL;
+
+	atomic_add(refresh, &event->event_limit);
+	perf_event_enable(event);
+
+	return 0;
+}
+
+enum event_type_t {
+	EVENT_FLEXIBLE = 0x1,
+	EVENT_PINNED = 0x2,
+	EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
+};
+
+static void ctx_sched_out(struct perf_event_context *ctx,
+			  struct perf_cpu_context *cpuctx,
+			  enum event_type_t event_type)
+{
+	struct perf_event *event;
+
+	raw_spin_lock(&ctx->lock);
+	ctx->is_active = 0;
+	if (likely(!ctx->nr_events))
+		goto out;
+	update_context_time(ctx);
+
+	perf_disable();
+	if (!ctx->nr_active)
+		goto out_enable;
+
+	if (event_type & EVENT_PINNED)
+		list_for_each_entry(event, &ctx->pinned_groups, group_entry)
+			group_sched_out(event, cpuctx, ctx);
+
+	if (event_type & EVENT_FLEXIBLE)
+		list_for_each_entry(event, &ctx->flexible_groups, group_entry)
+			group_sched_out(event, cpuctx, ctx);
+
+ out_enable:
+	perf_enable();
+ out:
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Test whether two contexts are equivalent, i.e. whether they
+ * have both been cloned from the same version of the same context
+ * and they both have the same number of enabled events.
+ * If the number of enabled events is the same, then the set
+ * of enabled events should be the same, because these are both
+ * inherited contexts, therefore we can't access individual events
+ * in them directly with an fd; we can only enable/disable all
+ * events via prctl, or enable/disable all events in a family
+ * via ioctl, which will have the same effect on both contexts.
+ */
+static int context_equiv(struct perf_event_context *ctx1,
+			 struct perf_event_context *ctx2)
+{
+	return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
+		&& ctx1->parent_gen == ctx2->parent_gen
+		&& !ctx1->pin_count && !ctx2->pin_count;
+}
+
+static void __perf_event_sync_stat(struct perf_event *event,
+				     struct perf_event *next_event)
+{
+	u64 value;
+
+	if (!event->attr.inherit_stat)
+		return;
+
+	/*
+	 * Update the event value, we cannot use perf_event_read()
+	 * because we're in the middle of a context switch and have IRQs
+	 * disabled, which upsets smp_call_function_single(), however
+	 * we know the event must be on the current CPU, therefore we
+	 * don't need to use it.
+	 */
+	switch (event->state) {
+	case PERF_EVENT_STATE_ACTIVE:
+		event->pmu->read(event);
+		/* fall-through */
+
+	case PERF_EVENT_STATE_INACTIVE:
+		update_event_times(event);
+		break;
+
+	default:
+		break;
+	}
+
+	/*
+	 * In order to keep per-task stats reliable we need to flip the event
+	 * values when we flip the contexts.
+	 */
+	value = local64_read(&next_event->count);
+	value = local64_xchg(&event->count, value);
+	local64_set(&next_event->count, value);
+
+	swap(event->total_time_enabled, next_event->total_time_enabled);
+	swap(event->total_time_running, next_event->total_time_running);
+
+	/*
+	 * Since we swizzled the values, update the user visible data too.
+	 */
+	perf_event_update_userpage(event);
+	perf_event_update_userpage(next_event);
+}
+
+#define list_next_entry(pos, member) \
+	list_entry(pos->member.next, typeof(*pos), member)
+
+static void perf_event_sync_stat(struct perf_event_context *ctx,
+				   struct perf_event_context *next_ctx)
+{
+	struct perf_event *event, *next_event;
+
+	if (!ctx->nr_stat)
+		return;
+
+	update_context_time(ctx);
+
+	event = list_first_entry(&ctx->event_list,
+				   struct perf_event, event_entry);
+
+	next_event = list_first_entry(&next_ctx->event_list,
+					struct perf_event, event_entry);
+
+	while (&event->event_entry != &ctx->event_list &&
+	       &next_event->event_entry != &next_ctx->event_list) {
+
+		__perf_event_sync_stat(event, next_event);
+
+		event = list_next_entry(event, event_entry);
+		next_event = list_next_entry(next_event, event_entry);
+	}
+}
+
+/*
+ * Called from scheduler to remove the events of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each event and update the event value in event->count.
+ *
+ * This does not protect us against NMI, but disable()
+ * sets the disabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * not restart the event.
+ */
+void perf_event_task_sched_out(struct task_struct *task,
+				 struct task_struct *next)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = task->perf_event_ctxp;
+	struct perf_event_context *next_ctx;
+	struct perf_event_context *parent;
+	int do_switch = 1;
+
+	perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
+
+	if (likely(!ctx || !cpuctx->task_ctx))
+		return;
+
+	rcu_read_lock();
+	parent = rcu_dereference(ctx->parent_ctx);
+	next_ctx = next->perf_event_ctxp;
+	if (parent && next_ctx &&
+	    rcu_dereference(next_ctx->parent_ctx) == parent) {
+		/*
+		 * Looks like the two contexts are clones, so we might be
+		 * able to optimize the context switch.  We lock both
+		 * contexts and check that they are clones under the
+		 * lock (including re-checking that neither has been
+		 * uncloned in the meantime).  It doesn't matter which
+		 * order we take the locks because no other cpu could
+		 * be trying to lock both of these tasks.
+		 */
+		raw_spin_lock(&ctx->lock);
+		raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
+		if (context_equiv(ctx, next_ctx)) {
+			/*
+			 * XXX do we need a memory barrier of sorts
+			 * wrt to rcu_dereference() of perf_event_ctxp
+			 */
+			task->perf_event_ctxp = next_ctx;
+			next->perf_event_ctxp = ctx;
+			ctx->task = next;
+			next_ctx->task = task;
+			do_switch = 0;
+
+			perf_event_sync_stat(ctx, next_ctx);
+		}
+		raw_spin_unlock(&next_ctx->lock);
+		raw_spin_unlock(&ctx->lock);
+	}
+	rcu_read_unlock();
+
+	if (do_switch) {
+		ctx_sched_out(ctx, cpuctx, EVENT_ALL);
+		cpuctx->task_ctx = NULL;
+	}
+}
+
+static void task_ctx_sched_out(struct perf_event_context *ctx,
+			       enum event_type_t event_type)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+
+	if (!cpuctx->task_ctx)
+		return;
+
+	if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+		return;
+
+	ctx_sched_out(ctx, cpuctx, event_type);
+	cpuctx->task_ctx = NULL;
+}
+
+/*
+ * Called with IRQs disabled
+ */
+static void __perf_event_task_sched_out(struct perf_event_context *ctx)
+{
+	task_ctx_sched_out(ctx, EVENT_ALL);
+}
+
+/*
+ * Called with IRQs disabled
+ */
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			      enum event_type_t event_type)
+{
+	ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
+}
+
+static void
+ctx_pinned_sched_in(struct perf_event_context *ctx,
+		    struct perf_cpu_context *cpuctx)
+{
+	struct perf_event *event;
+
+	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+		if (event->state <= PERF_EVENT_STATE_OFF)
+			continue;
+		if (event->cpu != -1 && event->cpu != smp_processor_id())
+			continue;
+
+		if (group_can_go_on(event, cpuctx, 1))
+			group_sched_in(event, cpuctx, ctx);
+
+		/*
+		 * If this pinned group hasn't been scheduled,
+		 * put it in error state.
+		 */
+		if (event->state == PERF_EVENT_STATE_INACTIVE) {
+			update_group_times(event);
+			event->state = PERF_EVENT_STATE_ERROR;
+		}
+	}
+}
+
+static void
+ctx_flexible_sched_in(struct perf_event_context *ctx,
+		      struct perf_cpu_context *cpuctx)
+{
+	struct perf_event *event;
+	int can_add_hw = 1;
+
+	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+		/* Ignore events in OFF or ERROR state */
+		if (event->state <= PERF_EVENT_STATE_OFF)
+			continue;
+		/*
+		 * Listen to the 'cpu' scheduling filter constraint
+		 * of events:
+		 */
+		if (event->cpu != -1 && event->cpu != smp_processor_id())
+			continue;
+
+		if (group_can_go_on(event, cpuctx, can_add_hw))
+			if (group_sched_in(event, cpuctx, ctx))
+				can_add_hw = 0;
+	}
+}
+
+static void
+ctx_sched_in(struct perf_event_context *ctx,
+	     struct perf_cpu_context *cpuctx,
+	     enum event_type_t event_type)
+{
+	raw_spin_lock(&ctx->lock);
+	ctx->is_active = 1;
+	if (likely(!ctx->nr_events))
+		goto out;
+
+	ctx->timestamp = perf_clock();
+
+	perf_disable();
+
+	/*
+	 * First go through the list and put on any pinned groups
+	 * in order to give them the best chance of going on.
+	 */
+	if (event_type & EVENT_PINNED)
+		ctx_pinned_sched_in(ctx, cpuctx);
+
+	/* Then walk through the lower prio flexible groups */
+	if (event_type & EVENT_FLEXIBLE)
+		ctx_flexible_sched_in(ctx, cpuctx);
+
+	perf_enable();
+ out:
+	raw_spin_unlock(&ctx->lock);
+}
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+			     enum event_type_t event_type)
+{
+	struct perf_event_context *ctx = &cpuctx->ctx;
+
+	ctx_sched_in(ctx, cpuctx, event_type);
+}
+
+static void task_ctx_sched_in(struct task_struct *task,
+			      enum event_type_t event_type)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = task->perf_event_ctxp;
+
+	if (likely(!ctx))
+		return;
+	if (cpuctx->task_ctx == ctx)
+		return;
+	ctx_sched_in(ctx, cpuctx, event_type);
+	cpuctx->task_ctx = ctx;
+}
+/*
+ * Called from scheduler to add the events of the current task
+ * with interrupts disabled.
+ *
+ * We restore the event value and then enable it.
+ *
+ * This does not protect us against NMI, but enable()
+ * sets the enabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * keep the event running.
+ */
+void perf_event_task_sched_in(struct task_struct *task)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = task->perf_event_ctxp;
+
+	if (likely(!ctx))
+		return;
+
+	if (cpuctx->task_ctx == ctx)
+		return;
+
+	perf_disable();
+
+	/*
+	 * We want to keep the following priority order:
+	 * cpu pinned (that don't need to move), task pinned,
+	 * cpu flexible, task flexible.
+	 */
+	cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+
+	ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
+	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
+	ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
+
+	cpuctx->task_ctx = ctx;
+
+	perf_enable();
+}
+
+#define MAX_INTERRUPTS (~0ULL)
+
+static void perf_log_throttle(struct perf_event *event, int enable);
+
+static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
+{
+	u64 frequency = event->attr.sample_freq;
+	u64 sec = NSEC_PER_SEC;
+	u64 divisor, dividend;
+
+	int count_fls, nsec_fls, frequency_fls, sec_fls;
+
+	count_fls = fls64(count);
+	nsec_fls = fls64(nsec);
+	frequency_fls = fls64(frequency);
+	sec_fls = 30;
+
+	/*
+	 * We got @count in @nsec, with a target of sample_freq HZ
+	 * the target period becomes:
+	 *
+	 *             @count * 10^9
+	 * period = -------------------
+	 *          @nsec * sample_freq
+	 *
+	 */
+
+	/*
+	 * Reduce accuracy by one bit such that @a and @b converge
+	 * to a similar magnitude.
+	 */
+#define REDUCE_FLS(a, b) 		\
+do {					\
+	if (a##_fls > b##_fls) {	\
+		a >>= 1;		\
+		a##_fls--;		\
+	} else {			\
+		b >>= 1;		\
+		b##_fls--;		\
+	}				\
+} while (0)
+
+	/*
+	 * Reduce accuracy until either term fits in a u64, then proceed with
+	 * the other, so that finally we can do a u64/u64 division.
+	 */
+	while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
+		REDUCE_FLS(nsec, frequency);
+		REDUCE_FLS(sec, count);
+	}
+
+	if (count_fls + sec_fls > 64) {
+		divisor = nsec * frequency;
+
+		while (count_fls + sec_fls > 64) {
+			REDUCE_FLS(count, sec);
+			divisor >>= 1;
+		}
+
+		dividend = count * sec;
+	} else {
+		dividend = count * sec;
+
+		while (nsec_fls + frequency_fls > 64) {
+			REDUCE_FLS(nsec, frequency);
+			dividend >>= 1;
+		}
+
+		divisor = nsec * frequency;
+	}
+
+	if (!divisor)
+		return dividend;
+
+	return div64_u64(dividend, divisor);
+}
+
+static void perf_event_stop(struct perf_event *event)
+{
+	if (!event->pmu->stop)
+		return event->pmu->disable(event);
+
+	return event->pmu->stop(event);
+}
+
+static int perf_event_start(struct perf_event *event)
+{
+	if (!event->pmu->start)
+		return event->pmu->enable(event);
+
+	return event->pmu->start(event);
+}
+
+static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 period, sample_period;
+	s64 delta;
+
+	period = perf_calculate_period(event, nsec, count);
+
+	delta = (s64)(period - hwc->sample_period);
+	delta = (delta + 7) / 8; /* low pass filter */
+
+	sample_period = hwc->sample_period + delta;
+
+	if (!sample_period)
+		sample_period = 1;
+
+	hwc->sample_period = sample_period;
+
+	if (local64_read(&hwc->period_left) > 8*sample_period) {
+		perf_disable();
+		perf_event_stop(event);
+		local64_set(&hwc->period_left, 0);
+		perf_event_start(event);
+		perf_enable();
+	}
+}
+
+static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
+{
+	struct perf_event *event;
+	struct hw_perf_event *hwc;
+	u64 interrupts, now;
+	s64 delta;
+
+	raw_spin_lock(&ctx->lock);
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (event->state != PERF_EVENT_STATE_ACTIVE)
+			continue;
+
+		if (event->cpu != -1 && event->cpu != smp_processor_id())
+			continue;
+
+		hwc = &event->hw;
+
+		interrupts = hwc->interrupts;
+		hwc->interrupts = 0;
+
+		/*
+		 * unthrottle events on the tick
+		 */
+		if (interrupts == MAX_INTERRUPTS) {
+			perf_log_throttle(event, 1);
+			perf_disable();
+			event->pmu->unthrottle(event);
+			perf_enable();
+		}
+
+		if (!event->attr.freq || !event->attr.sample_freq)
+			continue;
+
+		perf_disable();
+		event->pmu->read(event);
+		now = local64_read(&event->count);
+		delta = now - hwc->freq_count_stamp;
+		hwc->freq_count_stamp = now;
+
+		if (delta > 0)
+			perf_adjust_period(event, TICK_NSEC, delta);
+		perf_enable();
+	}
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Round-robin a context's events:
+ */
+static void rotate_ctx(struct perf_event_context *ctx)
+{
+	raw_spin_lock(&ctx->lock);
+
+	/* Rotate the first entry last of non-pinned groups */
+	list_rotate_left(&ctx->flexible_groups);
+
+	raw_spin_unlock(&ctx->lock);
+}
+
+void perf_event_task_tick(struct task_struct *curr)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx;
+	int rotate = 0;
+
+	if (!atomic_read(&nr_events))
+		return;
+
+	cpuctx = &__get_cpu_var(perf_cpu_context);
+	if (cpuctx->ctx.nr_events &&
+	    cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
+		rotate = 1;
+
+	ctx = curr->perf_event_ctxp;
+	if (ctx && ctx->nr_events && ctx->nr_events != ctx->nr_active)
+		rotate = 1;
+
+	perf_ctx_adjust_freq(&cpuctx->ctx);
+	if (ctx)
+		perf_ctx_adjust_freq(ctx);
+
+	if (!rotate)
+		return;
+
+	perf_disable();
+	cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+	if (ctx)
+		task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
+
+	rotate_ctx(&cpuctx->ctx);
+	if (ctx)
+		rotate_ctx(ctx);
+
+	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
+	if (ctx)
+		task_ctx_sched_in(curr, EVENT_FLEXIBLE);
+	perf_enable();
+}
+
+static int event_enable_on_exec(struct perf_event *event,
+				struct perf_event_context *ctx)
+{
+	if (!event->attr.enable_on_exec)
+		return 0;
+
+	event->attr.enable_on_exec = 0;
+	if (event->state >= PERF_EVENT_STATE_INACTIVE)
+		return 0;
+
+	__perf_event_mark_enabled(event, ctx);
+
+	return 1;
+}
+
+/*
+ * Enable all of a task's events that have been marked enable-on-exec.
+ * This expects task == current.
+ */
+static void perf_event_enable_on_exec(struct task_struct *task)
+{
+	struct perf_event_context *ctx;
+	struct perf_event *event;
+	unsigned long flags;
+	int enabled = 0;
+	int ret;
+
+	local_irq_save(flags);
+	ctx = task->perf_event_ctxp;
+	if (!ctx || !ctx->nr_events)
+		goto out;
+
+	__perf_event_task_sched_out(ctx);
+
+	raw_spin_lock(&ctx->lock);
+
+	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+		ret = event_enable_on_exec(event, ctx);
+		if (ret)
+			enabled = 1;
+	}
+
+	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+		ret = event_enable_on_exec(event, ctx);
+		if (ret)
+			enabled = 1;
+	}
+
+	/*
+	 * Unclone this context if we enabled any event.
+	 */
+	if (enabled)
+		unclone_ctx(ctx);
+
+	raw_spin_unlock(&ctx->lock);
+
+	perf_event_task_sched_in(task);
+ out:
+	local_irq_restore(flags);
+}
+
+/*
+ * Cross CPU call to read the hardware event
+ */
+static void __perf_event_read(void *info)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event *event = info;
+	struct perf_event_context *ctx = event->ctx;
+
+	/*
+	 * If this is a task context, we need to check whether it is
+	 * the current task context of this cpu.  If not it has been
+	 * scheduled out before the smp call arrived.  In that case
+	 * event->count would have been updated to a recent sample
+	 * when the event was scheduled out.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx)
+		return;
+
+	raw_spin_lock(&ctx->lock);
+	update_context_time(ctx);
+	update_event_times(event);
+	raw_spin_unlock(&ctx->lock);
+
+	event->pmu->read(event);
+}
+
+static inline u64 perf_event_count(struct perf_event *event)
+{
+	return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
+static u64 perf_event_read(struct perf_event *event)
+{
+	/*
+	 * If event is enabled and currently active on a CPU, update the
+	 * value in the event structure:
+	 */
+	if (event->state == PERF_EVENT_STATE_ACTIVE) {
+		smp_call_function_single(event->oncpu,
+					 __perf_event_read, event, 1);
+	} else if (event->state == PERF_EVENT_STATE_INACTIVE) {
+		struct perf_event_context *ctx = event->ctx;
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&ctx->lock, flags);
+		update_context_time(ctx);
+		update_event_times(event);
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+
+	return perf_event_count(event);
+}
+
+/*
+ * Initialize the perf_event context in a task_struct:
+ */
+static void
+__perf_event_init_context(struct perf_event_context *ctx,
+			    struct task_struct *task)
+{
+	raw_spin_lock_init(&ctx->lock);
+	mutex_init(&ctx->mutex);
+	INIT_LIST_HEAD(&ctx->pinned_groups);
+	INIT_LIST_HEAD(&ctx->flexible_groups);
+	INIT_LIST_HEAD(&ctx->event_list);
+	atomic_set(&ctx->refcount, 1);
+	ctx->task = task;
+}
+
+static struct perf_event_context *find_get_context(pid_t pid, int cpu)
+{
+	struct perf_event_context *ctx;
+	struct perf_cpu_context *cpuctx;
+	struct task_struct *task;
+	unsigned long flags;
+	int err;
+
+	if (pid == -1 && cpu != -1) {
+		/* Must be root to operate on a CPU event: */
+		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+			return ERR_PTR(-EACCES);
+
+		if (cpu < 0 || cpu >= nr_cpumask_bits)
+			return ERR_PTR(-EINVAL);
+
+		/*
+		 * We could be clever and allow to attach a event to an
+		 * offline CPU and activate it when the CPU comes up, but
+		 * that's for later.
+		 */
+		if (!cpu_online(cpu))
+			return ERR_PTR(-ENODEV);
+
+		cpuctx = &per_cpu(perf_cpu_context, cpu);
+		ctx = &cpuctx->ctx;
+		get_ctx(ctx);
+
+		return ctx;
+	}
+
+	rcu_read_lock();
+	if (!pid)
+		task = current;
+	else
+		task = find_task_by_vpid(pid);
+	if (task)
+		get_task_struct(task);
+	rcu_read_unlock();
+
+	if (!task)
+		return ERR_PTR(-ESRCH);
+
+	/*
+	 * Can't attach events to a dying task.
+	 */
+	err = -ESRCH;
+	if (task->flags & PF_EXITING)
+		goto errout;
+
+	/* Reuse ptrace permission checks for now. */
+	err = -EACCES;
+	if (!ptrace_may_access(task, PTRACE_MODE_READ))
+		goto errout;
+
+ retry:
+	ctx = perf_lock_task_context(task, &flags);
+	if (ctx) {
+		unclone_ctx(ctx);
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+
+	if (!ctx) {
+		ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+		err = -ENOMEM;
+		if (!ctx)
+			goto errout;
+		__perf_event_init_context(ctx, task);
+		get_ctx(ctx);
+		if (cmpxchg(&task->perf_event_ctxp, NULL, ctx)) {
+			/*
+			 * We raced with some other task; use
+			 * the context they set.
+			 */
+			kfree(ctx);
+			goto retry;
+		}
+		get_task_struct(task);
+	}
+
+	put_task_struct(task);
+	return ctx;
+
+ errout:
+	put_task_struct(task);
+	return ERR_PTR(err);
+}
+
+static void perf_event_free_filter(struct perf_event *event);
+
+static void free_event_rcu(struct rcu_head *head)
+{
+	struct perf_event *event;
+
+	event = container_of(head, struct perf_event, rcu_head);
+	if (event->ns)
+		put_pid_ns(event->ns);
+	perf_event_free_filter(event);
+	kfree(event);
+}
+
+static void perf_pending_sync(struct perf_event *event);
+static void perf_buffer_put(struct perf_buffer *buffer);
+
+static void free_event(struct perf_event *event)
+{
+	perf_pending_sync(event);
+
+	if (!event->parent) {
+		atomic_dec(&nr_events);
+		if (event->attr.mmap || event->attr.mmap_data)
+			atomic_dec(&nr_mmap_events);
+		if (event->attr.comm)
+			atomic_dec(&nr_comm_events);
+		if (event->attr.task)
+			atomic_dec(&nr_task_events);
+	}
+
+	if (event->buffer) {
+		perf_buffer_put(event->buffer);
+		event->buffer = NULL;
+	}
+
+	if (event->destroy)
+		event->destroy(event);
+
+	put_ctx(event->ctx);
+	call_rcu(&event->rcu_head, free_event_rcu);
+}
+
+int perf_event_release_kernel(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	/*
+	 * Remove from the PMU, can't get re-enabled since we got
+	 * here because the last ref went.
+	 */
+	perf_event_disable(event);
+
+	WARN_ON_ONCE(ctx->parent_ctx);
+	/*
+	 * There are two ways this annotation is useful:
+	 *
+	 *  1) there is a lock recursion from perf_event_exit_task
+	 *     see the comment there.
+	 *
+	 *  2) there is a lock-inversion with mmap_sem through
+	 *     perf_event_read_group(), which takes faults while
+	 *     holding ctx->mutex, however this is called after
+	 *     the last filedesc died, so there is no possibility
+	 *     to trigger the AB-BA case.
+	 */
+	mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
+	raw_spin_lock_irq(&ctx->lock);
+	perf_group_detach(event);
+	list_del_event(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+	mutex_unlock(&ctx->mutex);
+
+	mutex_lock(&event->owner->perf_event_mutex);
+	list_del_init(&event->owner_entry);
+	mutex_unlock(&event->owner->perf_event_mutex);
+	put_task_struct(event->owner);
+
+	free_event(event);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+	struct perf_event *event = file->private_data;
+
+	file->private_data = NULL;
+
+	return perf_event_release_kernel(event);
+}
+
+static int perf_event_read_size(struct perf_event *event)
+{
+	int entry = sizeof(u64); /* value */
+	int size = 0;
+	int nr = 1;
+
+	if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		size += sizeof(u64);
+
+	if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		size += sizeof(u64);
+
+	if (event->attr.read_format & PERF_FORMAT_ID)
+		entry += sizeof(u64);
+
+	if (event->attr.read_format & PERF_FORMAT_GROUP) {
+		nr += event->group_leader->nr_siblings;
+		size += sizeof(u64);
+	}
+
+	size += entry * nr;
+
+	return size;
+}
+
+u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+	struct perf_event *child;
+	u64 total = 0;
+
+	*enabled = 0;
+	*running = 0;
+
+	mutex_lock(&event->child_mutex);
+	total += perf_event_read(event);
+	*enabled += event->total_time_enabled +
+			atomic64_read(&event->child_total_time_enabled);
+	*running += event->total_time_running +
+			atomic64_read(&event->child_total_time_running);
+
+	list_for_each_entry(child, &event->child_list, child_list) {
+		total += perf_event_read(child);
+		*enabled += child->total_time_enabled;
+		*running += child->total_time_running;
+	}
+	mutex_unlock(&event->child_mutex);
+
+	return total;
+}
+EXPORT_SYMBOL_GPL(perf_event_read_value);
+
+static int perf_event_read_group(struct perf_event *event,
+				   u64 read_format, char __user *buf)
+{
+	struct perf_event *leader = event->group_leader, *sub;
+	int n = 0, size = 0, ret = -EFAULT;
+	struct perf_event_context *ctx = leader->ctx;
+	u64 values[5];
+	u64 count, enabled, running;
+
+	mutex_lock(&ctx->mutex);
+	count = perf_event_read_value(leader, &enabled, &running);
+
+	values[n++] = 1 + leader->nr_siblings;
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		values[n++] = enabled;
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		values[n++] = running;
+	values[n++] = count;
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(leader);
+
+	size = n * sizeof(u64);
+
+	if (copy_to_user(buf, values, size))
+		goto unlock;
+
+	ret = size;
+
+	list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+		n = 0;
+
+		values[n++] = perf_event_read_value(sub, &enabled, &running);
+		if (read_format & PERF_FORMAT_ID)
+			values[n++] = primary_event_id(sub);
+
+		size = n * sizeof(u64);
+
+		if (copy_to_user(buf + ret, values, size)) {
+			ret = -EFAULT;
+			goto unlock;
+		}
+
+		ret += size;
+	}
+unlock:
+	mutex_unlock(&ctx->mutex);
+
+	return ret;
+}
+
+static int perf_event_read_one(struct perf_event *event,
+				 u64 read_format, char __user *buf)
+{
+	u64 enabled, running;
+	u64 values[4];
+	int n = 0;
+
+	values[n++] = perf_event_read_value(event, &enabled, &running);
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		values[n++] = enabled;
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		values[n++] = running;
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(event);
+
+	if (copy_to_user(buf, values, n * sizeof(u64)))
+		return -EFAULT;
+
+	return n * sizeof(u64);
+}
+
+/*
+ * Read the performance event - simple non blocking version for now
+ */
+static ssize_t
+perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
+{
+	u64 read_format = event->attr.read_format;
+	int ret;
+
+	/*
+	 * Return end-of-file for a read on a event that is in
+	 * error state (i.e. because it was pinned but it couldn't be
+	 * scheduled on to the CPU at some point).
+	 */
+	if (event->state == PERF_EVENT_STATE_ERROR)
+		return 0;
+
+	if (count < perf_event_read_size(event))
+		return -ENOSPC;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+	if (read_format & PERF_FORMAT_GROUP)
+		ret = perf_event_read_group(event, read_format, buf);
+	else
+		ret = perf_event_read_one(event, read_format, buf);
+
+	return ret;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct perf_event *event = file->private_data;
+
+	return perf_read_hw(event, buf, count);
+}
+
+static unsigned int perf_poll(struct file *file, poll_table *wait)
+{
+	struct perf_event *event = file->private_data;
+	struct perf_buffer *buffer;
+	unsigned int events = POLL_HUP;
+
+	rcu_read_lock();
+	buffer = rcu_dereference(event->buffer);
+	if (buffer)
+		events = atomic_xchg(&buffer->poll, 0);
+	rcu_read_unlock();
+
+	poll_wait(file, &event->waitq, wait);
+
+	return events;
+}
+
+static void perf_event_reset(struct perf_event *event)
+{
+	(void)perf_event_read(event);
+	local64_set(&event->count, 0);
+	perf_event_update_userpage(event);
+}
+
+/*
+ * Holding the top-level event's child_mutex means that any
+ * descendant process that has inherited this event will block
+ * in sync_child_event if it goes to exit, thus satisfying the
+ * task existence requirements of perf_event_enable/disable.
+ */
+static void perf_event_for_each_child(struct perf_event *event,
+					void (*func)(struct perf_event *))
+{
+	struct perf_event *child;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+	mutex_lock(&event->child_mutex);
+	func(event);
+	list_for_each_entry(child, &event->child_list, child_list)
+		func(child);
+	mutex_unlock(&event->child_mutex);
+}
+
+static void perf_event_for_each(struct perf_event *event,
+				  void (*func)(struct perf_event *))
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_event *sibling;
+
+	WARN_ON_ONCE(ctx->parent_ctx);
+	mutex_lock(&ctx->mutex);
+	event = event->group_leader;
+
+	perf_event_for_each_child(event, func);
+	func(event);
+	list_for_each_entry(sibling, &event->sibling_list, group_entry)
+		perf_event_for_each_child(event, func);
+	mutex_unlock(&ctx->mutex);
+}
+
+static int perf_event_period(struct perf_event *event, u64 __user *arg)
+{
+	struct perf_event_context *ctx = event->ctx;
+	int ret = 0;
+	u64 value;
+
+	if (!event->attr.sample_period)
+		return -EINVAL;
+
+	if (copy_from_user(&value, arg, sizeof(value)))
+		return -EFAULT;
+
+	if (!value)
+		return -EINVAL;
+
+	raw_spin_lock_irq(&ctx->lock);
+	if (event->attr.freq) {
+		if (value > sysctl_perf_event_sample_rate) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+
+		event->attr.sample_freq = value;
+	} else {
+		event->attr.sample_period = value;
+		event->hw.sample_period = value;
+	}
+unlock:
+	raw_spin_unlock_irq(&ctx->lock);
+
+	return ret;
+}
+
+static const struct file_operations perf_fops;
+
+static struct perf_event *perf_fget_light(int fd, int *fput_needed)
+{
+	struct file *file;
+
+	file = fget_light(fd, fput_needed);
+	if (!file)
+		return ERR_PTR(-EBADF);
+
+	if (file->f_op != &perf_fops) {
+		fput_light(file, *fput_needed);
+		*fput_needed = 0;
+		return ERR_PTR(-EBADF);
+	}
+
+	return file->private_data;
+}
+
+static int perf_event_set_output(struct perf_event *event,
+				 struct perf_event *output_event);
+static int perf_event_set_filter(struct perf_event *event, void __user *arg);
+
+static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct perf_event *event = file->private_data;
+	void (*func)(struct perf_event *);
+	u32 flags = arg;
+
+	switch (cmd) {
+	case PERF_EVENT_IOC_ENABLE:
+		func = perf_event_enable;
+		break;
+	case PERF_EVENT_IOC_DISABLE:
+		func = perf_event_disable;
+		break;
+	case PERF_EVENT_IOC_RESET:
+		func = perf_event_reset;
+		break;
+
+	case PERF_EVENT_IOC_REFRESH:
+		return perf_event_refresh(event, arg);
+
+	case PERF_EVENT_IOC_PERIOD:
+		return perf_event_period(event, (u64 __user *)arg);
+
+	case PERF_EVENT_IOC_SET_OUTPUT:
+	{
+		struct perf_event *output_event = NULL;
+		int fput_needed = 0;
+		int ret;
+
+		if (arg != -1) {
+			output_event = perf_fget_light(arg, &fput_needed);
+			if (IS_ERR(output_event))
+				return PTR_ERR(output_event);
+		}
+
+		ret = perf_event_set_output(event, output_event);
+		if (output_event)
+			fput_light(output_event->filp, fput_needed);
+
+		return ret;
+	}
+
+	case PERF_EVENT_IOC_SET_FILTER:
+		return perf_event_set_filter(event, (void __user *)arg);
+
+	default:
+		return -ENOTTY;
+	}
+
+	if (flags & PERF_IOC_FLAG_GROUP)
+		perf_event_for_each(event, func);
+	else
+		perf_event_for_each_child(event, func);
+
+	return 0;
+}
+
+int perf_event_task_enable(void)
+{
+	struct perf_event *event;
+
+	mutex_lock(&current->perf_event_mutex);
+	list_for_each_entry(event, &current->perf_event_list, owner_entry)
+		perf_event_for_each_child(event, perf_event_enable);
+	mutex_unlock(&current->perf_event_mutex);
+
+	return 0;
+}
+
+int perf_event_task_disable(void)
+{
+	struct perf_event *event;
+
+	mutex_lock(&current->perf_event_mutex);
+	list_for_each_entry(event, &current->perf_event_list, owner_entry)
+		perf_event_for_each_child(event, perf_event_disable);
+	mutex_unlock(&current->perf_event_mutex);
+
+	return 0;
+}
+
+#ifndef PERF_EVENT_INDEX_OFFSET
+# define PERF_EVENT_INDEX_OFFSET 0
+#endif
+
+static int perf_event_index(struct perf_event *event)
+{
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return 0;
+
+	return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
+}
+
+/*
+ * Callers need to ensure there can be no nesting of this function, otherwise
+ * the seqlock logic goes bad. We can not serialize this because the arch
+ * code calls this from NMI context.
+ */
+void perf_event_update_userpage(struct perf_event *event)
+{
+	struct perf_event_mmap_page *userpg;
+	struct perf_buffer *buffer;
+
+	rcu_read_lock();
+	buffer = rcu_dereference(event->buffer);
+	if (!buffer)
+		goto unlock;
+
+	userpg = buffer->user_page;
+
+	/*
+	 * Disable preemption so as to not let the corresponding user-space
+	 * spin too long if we get preempted.
+	 */
+	preempt_disable();
+	++userpg->lock;
+	barrier();
+	userpg->index = perf_event_index(event);
+	userpg->offset = perf_event_count(event);
+	if (event->state == PERF_EVENT_STATE_ACTIVE)
+		userpg->offset -= local64_read(&event->hw.prev_count);
+
+	userpg->time_enabled = event->total_time_enabled +
+			atomic64_read(&event->child_total_time_enabled);
+
+	userpg->time_running = event->total_time_running +
+			atomic64_read(&event->child_total_time_running);
+
+	barrier();
+	++userpg->lock;
+	preempt_enable();
+unlock:
+	rcu_read_unlock();
+}
+
+static unsigned long perf_data_size(struct perf_buffer *buffer);
+
+static void
+perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
+{
+	long max_size = perf_data_size(buffer);
+
+	if (watermark)
+		buffer->watermark = min(max_size, watermark);
+
+	if (!buffer->watermark)
+		buffer->watermark = max_size / 2;
+
+	if (flags & PERF_BUFFER_WRITABLE)
+		buffer->writable = 1;
+
+	atomic_set(&buffer->refcount, 1);
+}
+
+#ifndef CONFIG_PERF_USE_VMALLOC
+
+/*
+ * Back perf_mmap() with regular GFP_KERNEL-0 pages.
+ */
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+	if (pgoff > buffer->nr_pages)
+		return NULL;
+
+	if (pgoff == 0)
+		return virt_to_page(buffer->user_page);
+
+	return virt_to_page(buffer->data_pages[pgoff - 1]);
+}
+
+static void *perf_mmap_alloc_page(int cpu)
+{
+	struct page *page;
+	int node;
+
+	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
+	page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+	if (!page)
+		return NULL;
+
+	return page_address(page);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+	struct perf_buffer *buffer;
+	unsigned long size;
+	int i;
+
+	size = sizeof(struct perf_buffer);
+	size += nr_pages * sizeof(void *);
+
+	buffer = kzalloc(size, GFP_KERNEL);
+	if (!buffer)
+		goto fail;
+
+	buffer->user_page = perf_mmap_alloc_page(cpu);
+	if (!buffer->user_page)
+		goto fail_user_page;
+
+	for (i = 0; i < nr_pages; i++) {
+		buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
+		if (!buffer->data_pages[i])
+			goto fail_data_pages;
+	}
+
+	buffer->nr_pages = nr_pages;
+
+	perf_buffer_init(buffer, watermark, flags);
+
+	return buffer;
+
+fail_data_pages:
+	for (i--; i >= 0; i--)
+		free_page((unsigned long)buffer->data_pages[i]);
+
+	free_page((unsigned long)buffer->user_page);
+
+fail_user_page:
+	kfree(buffer);
+
+fail:
+	return NULL;
+}
+
+static void perf_mmap_free_page(unsigned long addr)
+{
+	struct page *page = virt_to_page((void *)addr);
+
+	page->mapping = NULL;
+	__free_page(page);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+	int i;
+
+	perf_mmap_free_page((unsigned long)buffer->user_page);
+	for (i = 0; i < buffer->nr_pages; i++)
+		perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
+	kfree(buffer);
+}
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+	return 0;
+}
+
+#else
+
+/*
+ * Back perf_mmap() with vmalloc memory.
+ *
+ * Required for architectures that have d-cache aliasing issues.
+ */
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+	return buffer->page_order;
+}
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+	if (pgoff > (1UL << page_order(buffer)))
+		return NULL;
+
+	return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
+}
+
+static void perf_mmap_unmark_page(void *addr)
+{
+	struct page *page = vmalloc_to_page(addr);
+
+	page->mapping = NULL;
+}
+
+static void perf_buffer_free_work(struct work_struct *work)
+{
+	struct perf_buffer *buffer;
+	void *base;
+	int i, nr;
+
+	buffer = container_of(work, struct perf_buffer, work);
+	nr = 1 << page_order(buffer);
+
+	base = buffer->user_page;
+	for (i = 0; i < nr + 1; i++)
+		perf_mmap_unmark_page(base + (i * PAGE_SIZE));
+
+	vfree(base);
+	kfree(buffer);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+	schedule_work(&buffer->work);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+	struct perf_buffer *buffer;
+	unsigned long size;
+	void *all_buf;
+
+	size = sizeof(struct perf_buffer);
+	size += sizeof(void *);
+
+	buffer = kzalloc(size, GFP_KERNEL);
+	if (!buffer)
+		goto fail;
+
+	INIT_WORK(&buffer->work, perf_buffer_free_work);
+
+	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
+	if (!all_buf)
+		goto fail_all_buf;
+
+	buffer->user_page = all_buf;
+	buffer->data_pages[0] = all_buf + PAGE_SIZE;
+	buffer->page_order = ilog2(nr_pages);
+	buffer->nr_pages = 1;
+
+	perf_buffer_init(buffer, watermark, flags);
+
+	return buffer;
+
+fail_all_buf:
+	kfree(buffer);
+
+fail:
+	return NULL;
+}
+
+#endif
+
+static unsigned long perf_data_size(struct perf_buffer *buffer)
+{
+	return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
+}
+
+static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct perf_event *event = vma->vm_file->private_data;
+	struct perf_buffer *buffer;
+	int ret = VM_FAULT_SIGBUS;
+
+	if (vmf->flags & FAULT_FLAG_MKWRITE) {
+		if (vmf->pgoff == 0)
+			ret = 0;
+		return ret;
+	}
+
+	rcu_read_lock();
+	buffer = rcu_dereference(event->buffer);
+	if (!buffer)
+		goto unlock;
+
+	if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
+		goto unlock;
+
+	vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
+	if (!vmf->page)
+		goto unlock;
+
+	get_page(vmf->page);
+	vmf->page->mapping = vma->vm_file->f_mapping;
+	vmf->page->index   = vmf->pgoff;
+
+	ret = 0;
+unlock:
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
+{
+	struct perf_buffer *buffer;
+
+	buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
+	perf_buffer_free(buffer);
+}
+
+static struct perf_buffer *perf_buffer_get(struct perf_event *event)
+{
+	struct perf_buffer *buffer;
+
+	rcu_read_lock();
+	buffer = rcu_dereference(event->buffer);
+	if (buffer) {
+		if (!atomic_inc_not_zero(&buffer->refcount))
+			buffer = NULL;
+	}
+	rcu_read_unlock();
+
+	return buffer;
+}
+
+static void perf_buffer_put(struct perf_buffer *buffer)
+{
+	if (!atomic_dec_and_test(&buffer->refcount))
+		return;
+
+	call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
+}
+
+static void perf_mmap_open(struct vm_area_struct *vma)
+{
+	struct perf_event *event = vma->vm_file->private_data;
+
+	atomic_inc(&event->mmap_count);
+}
+
+static void perf_mmap_close(struct vm_area_struct *vma)
+{
+	struct perf_event *event = vma->vm_file->private_data;
+
+	if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
+		unsigned long size = perf_data_size(event->buffer);
+		struct user_struct *user = event->mmap_user;
+		struct perf_buffer *buffer = event->buffer;
+
+		atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
+		vma->vm_mm->locked_vm -= event->mmap_locked;
+		rcu_assign_pointer(event->buffer, NULL);
+		mutex_unlock(&event->mmap_mutex);
+
+		perf_buffer_put(buffer);
+		free_uid(user);
+	}
+}
+
+static const struct vm_operations_struct perf_mmap_vmops = {
+	.open		= perf_mmap_open,
+	.close		= perf_mmap_close,
+	.fault		= perf_mmap_fault,
+	.page_mkwrite	= perf_mmap_fault,
+};
+
+static int perf_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct perf_event *event = file->private_data;
+	unsigned long user_locked, user_lock_limit;
+	struct user_struct *user = current_user();
+	unsigned long locked, lock_limit;
+	struct perf_buffer *buffer;
+	unsigned long vma_size;
+	unsigned long nr_pages;
+	long user_extra, extra;
+	int ret = 0, flags = 0;
+
+	/*
+	 * Don't allow mmap() of inherited per-task counters. This would
+	 * create a performance issue due to all children writing to the
+	 * same buffer.
+	 */
+	if (event->cpu == -1 && event->attr.inherit)
+		return -EINVAL;
+
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+
+	vma_size = vma->vm_end - vma->vm_start;
+	nr_pages = (vma_size / PAGE_SIZE) - 1;
+
+	/*
+	 * If we have buffer pages ensure they're a power-of-two number, so we
+	 * can do bitmasks instead of modulo.
+	 */
+	if (nr_pages != 0 && !is_power_of_2(nr_pages))
+		return -EINVAL;
+
+	if (vma_size != PAGE_SIZE * (1 + nr_pages))
+		return -EINVAL;
+
+	if (vma->vm_pgoff != 0)
+		return -EINVAL;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+	mutex_lock(&event->mmap_mutex);
+	if (event->buffer) {
+		if (event->buffer->nr_pages == nr_pages)
+			atomic_inc(&event->buffer->refcount);
+		else
+			ret = -EINVAL;
+		goto unlock;
+	}
+
+	user_extra = nr_pages + 1;
+	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
+
+	/*
+	 * Increase the limit linearly with more CPUs:
+	 */
+	user_lock_limit *= num_online_cpus();
+
+	user_locked = atomic_long_read(&user->locked_vm) + user_extra;
+
+	extra = 0;
+	if (user_locked > user_lock_limit)
+		extra = user_locked - user_lock_limit;
+
+	lock_limit = rlimit(RLIMIT_MEMLOCK);
+	lock_limit >>= PAGE_SHIFT;
+	locked = vma->vm_mm->locked_vm + extra;
+
+	if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
+		!capable(CAP_IPC_LOCK)) {
+		ret = -EPERM;
+		goto unlock;
+	}
+
+	WARN_ON(event->buffer);
+
+	if (vma->vm_flags & VM_WRITE)
+		flags |= PERF_BUFFER_WRITABLE;
+
+	buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
+				   event->cpu, flags);
+	if (!buffer) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+	rcu_assign_pointer(event->buffer, buffer);
+
+	atomic_long_add(user_extra, &user->locked_vm);
+	event->mmap_locked = extra;
+	event->mmap_user = get_current_user();
+	vma->vm_mm->locked_vm += event->mmap_locked;
+
+unlock:
+	if (!ret)
+		atomic_inc(&event->mmap_count);
+	mutex_unlock(&event->mmap_mutex);
+
+	vma->vm_flags |= VM_RESERVED;
+	vma->vm_ops = &perf_mmap_vmops;
+
+	return ret;
+}
+
+static int perf_fasync(int fd, struct file *filp, int on)
+{
+	struct inode *inode = filp->f_path.dentry->d_inode;
+	struct perf_event *event = filp->private_data;
+	int retval;
+
+	mutex_lock(&inode->i_mutex);
+	retval = fasync_helper(fd, filp, on, &event->fasync);
+	mutex_unlock(&inode->i_mutex);
+
+	if (retval < 0)
+		return retval;
+
+	return 0;
+}
+
+static const struct file_operations perf_fops = {
+	.llseek			= no_llseek,
+	.release		= perf_release,
+	.read			= perf_read,
+	.poll			= perf_poll,
+	.unlocked_ioctl		= perf_ioctl,
+	.compat_ioctl		= perf_ioctl,
+	.mmap			= perf_mmap,
+	.fasync			= perf_fasync,
+};
+
+/*
+ * Perf event wakeup
+ *
+ * If there's data, ensure we set the poll() state and publish everything
+ * to user-space before waking everybody up.
+ */
+
+void perf_event_wakeup(struct perf_event *event)
+{
+	wake_up_all(&event->waitq);
+
+	if (event->pending_kill) {
+		kill_fasync(&event->fasync, SIGIO, event->pending_kill);
+		event->pending_kill = 0;
+	}
+}
+
+/*
+ * Pending wakeups
+ *
+ * Handle the case where we need to wakeup up from NMI (or rq->lock) context.
+ *
+ * The NMI bit means we cannot possibly take locks. Therefore, maintain a
+ * single linked list and use cmpxchg() to add entries lockless.
+ */
+
+static void perf_pending_event(struct perf_pending_entry *entry)
+{
+	struct perf_event *event = container_of(entry,
+			struct perf_event, pending);
+
+	if (event->pending_disable) {
+		event->pending_disable = 0;
+		__perf_event_disable(event);
+	}
+
+	if (event->pending_wakeup) {
+		event->pending_wakeup = 0;
+		perf_event_wakeup(event);
+	}
+}
+
+#define PENDING_TAIL ((struct perf_pending_entry *)-1UL)
+
+static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
+	PENDING_TAIL,
+};
+
+static void perf_pending_queue(struct perf_pending_entry *entry,
+			       void (*func)(struct perf_pending_entry *))
+{
+	struct perf_pending_entry **head;
+
+	if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL)
+		return;
+
+	entry->func = func;
+
+	head = &get_cpu_var(perf_pending_head);
+
+	do {
+		entry->next = *head;
+	} while (cmpxchg(head, entry->next, entry) != entry->next);
+
+	set_perf_event_pending();
+
+	put_cpu_var(perf_pending_head);
+}
+
+static int __perf_pending_run(void)
+{
+	struct perf_pending_entry *list;
+	int nr = 0;
+
+	list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL);
+	while (list != PENDING_TAIL) {
+		void (*func)(struct perf_pending_entry *);
+		struct perf_pending_entry *entry = list;
+
+		list = list->next;
+
+		func = entry->func;
+		entry->next = NULL;
+		/*
+		 * Ensure we observe the unqueue before we issue the wakeup,
+		 * so that we won't be waiting forever.
+		 * -- see perf_not_pending().
+		 */
+		smp_wmb();
+
+		func(entry);
+		nr++;
+	}
+
+	return nr;
+}
+
+static inline int perf_not_pending(struct perf_event *event)
+{
+	/*
+	 * If we flush on whatever cpu we run, there is a chance we don't
+	 * need to wait.
+	 */
+	get_cpu();
+	__perf_pending_run();
+	put_cpu();
+
+	/*
+	 * Ensure we see the proper queue state before going to sleep
+	 * so that we do not miss the wakeup. -- see perf_pending_handle()
+	 */
+	smp_rmb();
+	return event->pending.next == NULL;
+}
+
+static void perf_pending_sync(struct perf_event *event)
+{
+	wait_event(event->waitq, perf_not_pending(event));
+}
+
+void perf_event_do_pending(void)
+{
+	__perf_pending_run();
+}
+
+/*
+ * Callchain support -- arch specific
+ */
+
+__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+	return NULL;
+}
+
+
+/*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	perf_guest_cbs = cbs;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	perf_guest_cbs = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+/*
+ * Output
+ */
+static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
+			      unsigned long offset, unsigned long head)
+{
+	unsigned long mask;
+
+	if (!buffer->writable)
+		return true;
+
+	mask = perf_data_size(buffer) - 1;
+
+	offset = (offset - tail) & mask;
+	head   = (head   - tail) & mask;
+
+	if ((int)(head - offset) < 0)
+		return false;
+
+	return true;
+}
+
+static void perf_output_wakeup(struct perf_output_handle *handle)
+{
+	atomic_set(&handle->buffer->poll, POLL_IN);
+
+	if (handle->nmi) {
+		handle->event->pending_wakeup = 1;
+		perf_pending_queue(&handle->event->pending,
+				   perf_pending_event);
+	} else
+		perf_event_wakeup(handle->event);
+}
+
+/*
+ * We need to ensure a later event_id doesn't publish a head when a former
+ * event isn't done writing. However since we need to deal with NMIs we
+ * cannot fully serialize things.
+ *
+ * We only publish the head (and generate a wakeup) when the outer-most
+ * event completes.
+ */
+static void perf_output_get_handle(struct perf_output_handle *handle)
+{
+	struct perf_buffer *buffer = handle->buffer;
+
+	preempt_disable();
+	local_inc(&buffer->nest);
+	handle->wakeup = local_read(&buffer->wakeup);
+}
+
+static void perf_output_put_handle(struct perf_output_handle *handle)
+{
+	struct perf_buffer *buffer = handle->buffer;
+	unsigned long head;
+
+again:
+	head = local_read(&buffer->head);
+
+	/*
+	 * IRQ/NMI can happen here, which means we can miss a head update.
+	 */
+
+	if (!local_dec_and_test(&buffer->nest))
+		goto out;
+
+	/*
+	 * Publish the known good head. Rely on the full barrier implied
+	 * by atomic_dec_and_test() order the buffer->head read and this
+	 * write.
+	 */
+	buffer->user_page->data_head = head;
+
+	/*
+	 * Now check if we missed an update, rely on the (compiler)
+	 * barrier in atomic_dec_and_test() to re-read buffer->head.
+	 */
+	if (unlikely(head != local_read(&buffer->head))) {
+		local_inc(&buffer->nest);
+		goto again;
+	}
+
+	if (handle->wakeup != local_read(&buffer->wakeup))
+		perf_output_wakeup(handle);
+
+ out:
+	preempt_enable();
+}
+
+__always_inline void perf_output_copy(struct perf_output_handle *handle,
+		      const void *buf, unsigned int len)
+{
+	do {
+		unsigned long size = min_t(unsigned long, handle->size, len);
+
+		memcpy(handle->addr, buf, size);
+
+		len -= size;
+		handle->addr += size;
+		buf += size;
+		handle->size -= size;
+		if (!handle->size) {
+			struct perf_buffer *buffer = handle->buffer;
+
+			handle->page++;
+			handle->page &= buffer->nr_pages - 1;
+			handle->addr = buffer->data_pages[handle->page];
+			handle->size = PAGE_SIZE << page_order(buffer);
+		}
+	} while (len);
+}
+
+int perf_output_begin(struct perf_output_handle *handle,
+		      struct perf_event *event, unsigned int size,
+		      int nmi, int sample)
+{
+	struct perf_buffer *buffer;
+	unsigned long tail, offset, head;
+	int have_lost;
+	struct {
+		struct perf_event_header header;
+		u64			 id;
+		u64			 lost;
+	} lost_event;
+
+	rcu_read_lock();
+	/*
+	 * For inherited events we send all the output towards the parent.
+	 */
+	if (event->parent)
+		event = event->parent;
+
+	buffer = rcu_dereference(event->buffer);
+	if (!buffer)
+		goto out;
+
+	handle->buffer	= buffer;
+	handle->event	= event;
+	handle->nmi	= nmi;
+	handle->sample	= sample;
+
+	if (!buffer->nr_pages)
+		goto out;
+
+	have_lost = local_read(&buffer->lost);
+	if (have_lost)
+		size += sizeof(lost_event);
+
+	perf_output_get_handle(handle);
+
+	do {
+		/*
+		 * Userspace could choose to issue a mb() before updating the
+		 * tail pointer. So that all reads will be completed before the
+		 * write is issued.
+		 */
+		tail = ACCESS_ONCE(buffer->user_page->data_tail);
+		smp_rmb();
+		offset = head = local_read(&buffer->head);
+		head += size;
+		if (unlikely(!perf_output_space(buffer, tail, offset, head)))
+			goto fail;
+	} while (local_cmpxchg(&buffer->head, offset, head) != offset);
+
+	if (head - local_read(&buffer->wakeup) > buffer->watermark)
+		local_add(buffer->watermark, &buffer->wakeup);
+
+	handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
+	handle->page &= buffer->nr_pages - 1;
+	handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
+	handle->addr = buffer->data_pages[handle->page];
+	handle->addr += handle->size;
+	handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
+
+	if (have_lost) {
+		lost_event.header.type = PERF_RECORD_LOST;
+		lost_event.header.misc = 0;
+		lost_event.header.size = sizeof(lost_event);
+		lost_event.id          = event->id;
+		lost_event.lost        = local_xchg(&buffer->lost, 0);
+
+		perf_output_put(handle, lost_event);
+	}
+
+	return 0;
+
+fail:
+	local_inc(&buffer->lost);
+	perf_output_put_handle(handle);
+out:
+	rcu_read_unlock();
+
+	return -ENOSPC;
+}
+
+void perf_output_end(struct perf_output_handle *handle)
+{
+	struct perf_event *event = handle->event;
+	struct perf_buffer *buffer = handle->buffer;
+
+	int wakeup_events = event->attr.wakeup_events;
+
+	if (handle->sample && wakeup_events) {
+		int events = local_inc_return(&buffer->events);
+		if (events >= wakeup_events) {
+			local_sub(wakeup_events, &buffer->events);
+			local_inc(&buffer->wakeup);
+		}
+	}
+
+	perf_output_put_handle(handle);
+	rcu_read_unlock();
+}
+
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+{
+	/*
+	 * only top level events have the pid namespace they were created in
+	 */
+	if (event->parent)
+		event = event->parent;
+
+	return task_tgid_nr_ns(p, event->ns);
+}
+
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+	/*
+	 * only top level events have the pid namespace they were created in
+	 */
+	if (event->parent)
+		event = event->parent;
+
+	return task_pid_nr_ns(p, event->ns);
+}
+
+static void perf_output_read_one(struct perf_output_handle *handle,
+				 struct perf_event *event)
+{
+	u64 read_format = event->attr.read_format;
+	u64 values[4];
+	int n = 0;
+
+	values[n++] = perf_event_count(event);
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+		values[n++] = event->total_time_enabled +
+			atomic64_read(&event->child_total_time_enabled);
+	}
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+		values[n++] = event->total_time_running +
+			atomic64_read(&event->child_total_time_running);
+	}
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(event);
+
+	perf_output_copy(handle, values, n * sizeof(u64));
+}
+
+/*
+ * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
+ */
+static void perf_output_read_group(struct perf_output_handle *handle,
+			    struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader, *sub;
+	u64 read_format = event->attr.read_format;
+	u64 values[5];
+	int n = 0;
+
+	values[n++] = 1 + leader->nr_siblings;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		values[n++] = leader->total_time_enabled;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		values[n++] = leader->total_time_running;
+
+	if (leader != event)
+		leader->pmu->read(leader);
+
+	values[n++] = perf_event_count(leader);
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(leader);
+
+	perf_output_copy(handle, values, n * sizeof(u64));
+
+	list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+		n = 0;
+
+		if (sub != event)
+			sub->pmu->read(sub);
+
+		values[n++] = perf_event_count(sub);
+		if (read_format & PERF_FORMAT_ID)
+			values[n++] = primary_event_id(sub);
+
+		perf_output_copy(handle, values, n * sizeof(u64));
+	}
+}
+
+static void perf_output_read(struct perf_output_handle *handle,
+			     struct perf_event *event)
+{
+	if (event->attr.read_format & PERF_FORMAT_GROUP)
+		perf_output_read_group(handle, event);
+	else
+		perf_output_read_one(handle, event);
+}
+
+void perf_output_sample(struct perf_output_handle *handle,
+			struct perf_event_header *header,
+			struct perf_sample_data *data,
+			struct perf_event *event)
+{
+	u64 sample_type = data->type;
+
+	perf_output_put(handle, *header);
+
+	if (sample_type & PERF_SAMPLE_IP)
+		perf_output_put(handle, data->ip);
+
+	if (sample_type & PERF_SAMPLE_TID)
+		perf_output_put(handle, data->tid_entry);
+
+	if (sample_type & PERF_SAMPLE_TIME)
+		perf_output_put(handle, data->time);
+
+	if (sample_type & PERF_SAMPLE_ADDR)
+		perf_output_put(handle, data->addr);
+
+	if (sample_type & PERF_SAMPLE_ID)
+		perf_output_put(handle, data->id);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		perf_output_put(handle, data->stream_id);
+
+	if (sample_type & PERF_SAMPLE_CPU)
+		perf_output_put(handle, data->cpu_entry);
+
+	if (sample_type & PERF_SAMPLE_PERIOD)
+		perf_output_put(handle, data->period);
+
+	if (sample_type & PERF_SAMPLE_READ)
+		perf_output_read(handle, event);
+
+	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+		if (data->callchain) {
+			int size = 1;
+
+			if (data->callchain)
+				size += data->callchain->nr;
+
+			size *= sizeof(u64);
+
+			perf_output_copy(handle, data->callchain, size);
+		} else {
+			u64 nr = 0;
+			perf_output_put(handle, nr);
+		}
+	}
+
+	if (sample_type & PERF_SAMPLE_RAW) {
+		if (data->raw) {
+			perf_output_put(handle, data->raw->size);
+			perf_output_copy(handle, data->raw->data,
+					 data->raw->size);
+		} else {
+			struct {
+				u32	size;
+				u32	data;
+			} raw = {
+				.size = sizeof(u32),
+				.data = 0,
+			};
+			perf_output_put(handle, raw);
+		}
+	}
+}
+
+void perf_prepare_sample(struct perf_event_header *header,
+			 struct perf_sample_data *data,
+			 struct perf_event *event,
+			 struct pt_regs *regs)
+{
+	u64 sample_type = event->attr.sample_type;
+
+	data->type = sample_type;
+
+	header->type = PERF_RECORD_SAMPLE;
+	header->size = sizeof(*header);
+
+	header->misc = 0;
+	header->misc |= perf_misc_flags(regs);
+
+	if (sample_type & PERF_SAMPLE_IP) {
+		data->ip = perf_instruction_pointer(regs);
+
+		header->size += sizeof(data->ip);
+	}
+
+	if (sample_type & PERF_SAMPLE_TID) {
+		/* namespace issues */
+		data->tid_entry.pid = perf_event_pid(event, current);
+		data->tid_entry.tid = perf_event_tid(event, current);
+
+		header->size += sizeof(data->tid_entry);
+	}
+
+	if (sample_type & PERF_SAMPLE_TIME) {
+		data->time = perf_clock();
+
+		header->size += sizeof(data->time);
+	}
+
+	if (sample_type & PERF_SAMPLE_ADDR)
+		header->size += sizeof(data->addr);
+
+	if (sample_type & PERF_SAMPLE_ID) {
+		data->id = primary_event_id(event);
+
+		header->size += sizeof(data->id);
+	}
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID) {
+		data->stream_id = event->id;
+
+		header->size += sizeof(data->stream_id);
+	}
+
+	if (sample_type & PERF_SAMPLE_CPU) {
+		data->cpu_entry.cpu		= raw_smp_processor_id();
+		data->cpu_entry.reserved	= 0;
+
+		header->size += sizeof(data->cpu_entry);
+	}
+
+	if (sample_type & PERF_SAMPLE_PERIOD)
+		header->size += sizeof(data->period);
+
+	if (sample_type & PERF_SAMPLE_READ)
+		header->size += perf_event_read_size(event);
+
+	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+		int size = 1;
+
+		data->callchain = perf_callchain(regs);
+
+		if (data->callchain)
+			size += data->callchain->nr;
+
+		header->size += size * sizeof(u64);
+	}
+
+	if (sample_type & PERF_SAMPLE_RAW) {
+		int size = sizeof(u32);
+
+		if (data->raw)
+			size += data->raw->size;
+		else
+			size += sizeof(u32);
+
+		WARN_ON_ONCE(size & (sizeof(u64)-1));
+		header->size += size;
+	}
+}
+
+static void perf_event_output(struct perf_event *event, int nmi,
+				struct perf_sample_data *data,
+				struct pt_regs *regs)
+{
+	struct perf_output_handle handle;
+	struct perf_event_header header;
+
+	perf_prepare_sample(&header, data, event, regs);
+
+	if (perf_output_begin(&handle, event, header.size, nmi, 1))
+		return;
+
+	perf_output_sample(&handle, &header, data, event);
+
+	perf_output_end(&handle);
+}
+
+/*
+ * read event_id
+ */
+
+struct perf_read_event {
+	struct perf_event_header	header;
+
+	u32				pid;
+	u32				tid;
+};
+
+static void
+perf_event_read_event(struct perf_event *event,
+			struct task_struct *task)
+{
+	struct perf_output_handle handle;
+	struct perf_read_event read_event = {
+		.header = {
+			.type = PERF_RECORD_READ,
+			.misc = 0,
+			.size = sizeof(read_event) + perf_event_read_size(event),
+		},
+		.pid = perf_event_pid(event, task),
+		.tid = perf_event_tid(event, task),
+	};
+	int ret;
+
+	ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, read_event);
+	perf_output_read(&handle, event);
+
+	perf_output_end(&handle);
+}
+
+/*
+ * task tracking -- fork/exit
+ *
+ * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
+ */
+
+struct perf_task_event {
+	struct task_struct		*task;
+	struct perf_event_context	*task_ctx;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				ppid;
+		u32				tid;
+		u32				ptid;
+		u64				time;
+	} event_id;
+};
+
+static void perf_event_task_output(struct perf_event *event,
+				     struct perf_task_event *task_event)
+{
+	struct perf_output_handle handle;
+	struct task_struct *task = task_event->task;
+	int size, ret;
+
+	size  = task_event->event_id.header.size;
+	ret = perf_output_begin(&handle, event, size, 0, 0);
+
+	if (ret)
+		return;
+
+	task_event->event_id.pid = perf_event_pid(event, task);
+	task_event->event_id.ppid = perf_event_pid(event, current);
+
+	task_event->event_id.tid = perf_event_tid(event, task);
+	task_event->event_id.ptid = perf_event_tid(event, current);
+
+	perf_output_put(&handle, task_event->event_id);
+
+	perf_output_end(&handle);
+}
+
+static int perf_event_task_match(struct perf_event *event)
+{
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
+		return 0;
+
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		return 0;
+
+	if (event->attr.comm || event->attr.mmap ||
+	    event->attr.mmap_data || event->attr.task)
+		return 1;
+
+	return 0;
+}
+
+static void perf_event_task_ctx(struct perf_event_context *ctx,
+				  struct perf_task_event *task_event)
+{
+	struct perf_event *event;
+
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (perf_event_task_match(event))
+			perf_event_task_output(event, task_event);
+	}
+}
+
+static void perf_event_task_event(struct perf_task_event *task_event)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx = task_event->task_ctx;
+
+	rcu_read_lock();
+	cpuctx = &get_cpu_var(perf_cpu_context);
+	perf_event_task_ctx(&cpuctx->ctx, task_event);
+	if (!ctx)
+		ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
+		perf_event_task_ctx(ctx, task_event);
+	put_cpu_var(perf_cpu_context);
+	rcu_read_unlock();
+}
+
+static void perf_event_task(struct task_struct *task,
+			      struct perf_event_context *task_ctx,
+			      int new)
+{
+	struct perf_task_event task_event;
+
+	if (!atomic_read(&nr_comm_events) &&
+	    !atomic_read(&nr_mmap_events) &&
+	    !atomic_read(&nr_task_events))
+		return;
+
+	task_event = (struct perf_task_event){
+		.task	  = task,
+		.task_ctx = task_ctx,
+		.event_id    = {
+			.header = {
+				.type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
+				.misc = 0,
+				.size = sizeof(task_event.event_id),
+			},
+			/* .pid  */
+			/* .ppid */
+			/* .tid  */
+			/* .ptid */
+			.time = perf_clock(),
+		},
+	};
+
+	perf_event_task_event(&task_event);
+}
+
+void perf_event_fork(struct task_struct *task)
+{
+	perf_event_task(task, NULL, 1);
+}
+
+/*
+ * comm tracking
+ */
+
+struct perf_comm_event {
+	struct task_struct	*task;
+	char			*comm;
+	int			comm_size;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				tid;
+	} event_id;
+};
+
+static void perf_event_comm_output(struct perf_event *event,
+				     struct perf_comm_event *comm_event)
+{
+	struct perf_output_handle handle;
+	int size = comm_event->event_id.header.size;
+	int ret = perf_output_begin(&handle, event, size, 0, 0);
+
+	if (ret)
+		return;
+
+	comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
+	comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
+
+	perf_output_put(&handle, comm_event->event_id);
+	perf_output_copy(&handle, comm_event->comm,
+				   comm_event->comm_size);
+	perf_output_end(&handle);
+}
+
+static int perf_event_comm_match(struct perf_event *event)
+{
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
+		return 0;
+
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		return 0;
+
+	if (event->attr.comm)
+		return 1;
+
+	return 0;
+}
+
+static void perf_event_comm_ctx(struct perf_event_context *ctx,
+				  struct perf_comm_event *comm_event)
+{
+	struct perf_event *event;
+
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (perf_event_comm_match(event))
+			perf_event_comm_output(event, comm_event);
+	}
+}
+
+static void perf_event_comm_event(struct perf_comm_event *comm_event)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx;
+	unsigned int size;
+	char comm[TASK_COMM_LEN];
+
+	memset(comm, 0, sizeof(comm));
+	strlcpy(comm, comm_event->task->comm, sizeof(comm));
+	size = ALIGN(strlen(comm)+1, sizeof(u64));
+
+	comm_event->comm = comm;
+	comm_event->comm_size = size;
+
+	comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
+
+	rcu_read_lock();
+	cpuctx = &get_cpu_var(perf_cpu_context);
+	perf_event_comm_ctx(&cpuctx->ctx, comm_event);
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
+		perf_event_comm_ctx(ctx, comm_event);
+	put_cpu_var(perf_cpu_context);
+	rcu_read_unlock();
+}
+
+void perf_event_comm(struct task_struct *task)
+{
+	struct perf_comm_event comm_event;
+
+	if (task->perf_event_ctxp)
+		perf_event_enable_on_exec(task);
+
+	if (!atomic_read(&nr_comm_events))
+		return;
+
+	comm_event = (struct perf_comm_event){
+		.task	= task,
+		/* .comm      */
+		/* .comm_size */
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_COMM,
+				.misc = 0,
+				/* .size */
+			},
+			/* .pid */
+			/* .tid */
+		},
+	};
+
+	perf_event_comm_event(&comm_event);
+}
+
+/*
+ * mmap tracking
+ */
+
+struct perf_mmap_event {
+	struct vm_area_struct	*vma;
+
+	const char		*file_name;
+	int			file_size;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				tid;
+		u64				start;
+		u64				len;
+		u64				pgoff;
+	} event_id;
+};
+
+static void perf_event_mmap_output(struct perf_event *event,
+				     struct perf_mmap_event *mmap_event)
+{
+	struct perf_output_handle handle;
+	int size = mmap_event->event_id.header.size;
+	int ret = perf_output_begin(&handle, event, size, 0, 0);
+
+	if (ret)
+		return;
+
+	mmap_event->event_id.pid = perf_event_pid(event, current);
+	mmap_event->event_id.tid = perf_event_tid(event, current);
+
+	perf_output_put(&handle, mmap_event->event_id);
+	perf_output_copy(&handle, mmap_event->file_name,
+				   mmap_event->file_size);
+	perf_output_end(&handle);
+}
+
+static int perf_event_mmap_match(struct perf_event *event,
+				   struct perf_mmap_event *mmap_event,
+				   int executable)
+{
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
+		return 0;
+
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		return 0;
+
+	if ((!executable && event->attr.mmap_data) ||
+	    (executable && event->attr.mmap))
+		return 1;
+
+	return 0;
+}
+
+static void perf_event_mmap_ctx(struct perf_event_context *ctx,
+				  struct perf_mmap_event *mmap_event,
+				  int executable)
+{
+	struct perf_event *event;
+
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (perf_event_mmap_match(event, mmap_event, executable))
+			perf_event_mmap_output(event, mmap_event);
+	}
+}
+
+static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx;
+	struct vm_area_struct *vma = mmap_event->vma;
+	struct file *file = vma->vm_file;
+	unsigned int size;
+	char tmp[16];
+	char *buf = NULL;
+	const char *name;
+
+	memset(tmp, 0, sizeof(tmp));
+
+	if (file) {
+		/*
+		 * d_path works from the end of the buffer backwards, so we
+		 * need to add enough zero bytes after the string to handle
+		 * the 64bit alignment we do later.
+		 */
+		buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
+		if (!buf) {
+			name = strncpy(tmp, "//enomem", sizeof(tmp));
+			goto got_name;
+		}
+		name = d_path(&file->f_path, buf, PATH_MAX);
+		if (IS_ERR(name)) {
+			name = strncpy(tmp, "//toolong", sizeof(tmp));
+			goto got_name;
+		}
+	} else {
+		if (arch_vma_name(mmap_event->vma)) {
+			name = strncpy(tmp, arch_vma_name(mmap_event->vma),
+				       sizeof(tmp));
+			goto got_name;
+		}
+
+		if (!vma->vm_mm) {
+			name = strncpy(tmp, "[vdso]", sizeof(tmp));
+			goto got_name;
+		} else if (vma->vm_start <= vma->vm_mm->start_brk &&
+				vma->vm_end >= vma->vm_mm->brk) {
+			name = strncpy(tmp, "[heap]", sizeof(tmp));
+			goto got_name;
+		} else if (vma->vm_start <= vma->vm_mm->start_stack &&
+				vma->vm_end >= vma->vm_mm->start_stack) {
+			name = strncpy(tmp, "[stack]", sizeof(tmp));
+			goto got_name;
+		}
+
+		name = strncpy(tmp, "//anon", sizeof(tmp));
+		goto got_name;
+	}
+
+got_name:
+	size = ALIGN(strlen(name)+1, sizeof(u64));
+
+	mmap_event->file_name = name;
+	mmap_event->file_size = size;
+
+	mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
+
+	rcu_read_lock();
+	cpuctx = &get_cpu_var(perf_cpu_context);
+	perf_event_mmap_ctx(&cpuctx->ctx, mmap_event, vma->vm_flags & VM_EXEC);
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
+		perf_event_mmap_ctx(ctx, mmap_event, vma->vm_flags & VM_EXEC);
+	put_cpu_var(perf_cpu_context);
+	rcu_read_unlock();
+
+	kfree(buf);
+}
+
+void perf_event_mmap(struct vm_area_struct *vma)
+{
+	struct perf_mmap_event mmap_event;
+
+	if (!atomic_read(&nr_mmap_events))
+		return;
+
+	mmap_event = (struct perf_mmap_event){
+		.vma	= vma,
+		/* .file_name */
+		/* .file_size */
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_MMAP,
+				.misc = PERF_RECORD_MISC_USER,
+				/* .size */
+			},
+			/* .pid */
+			/* .tid */
+			.start  = vma->vm_start,
+			.len    = vma->vm_end - vma->vm_start,
+			.pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
+		},
+	};
+
+	perf_event_mmap_event(&mmap_event);
+}
+
+/*
+ * IRQ throttle logging
+ */
+
+static void perf_log_throttle(struct perf_event *event, int enable)
+{
+	struct perf_output_handle handle;
+	int ret;
+
+	struct {
+		struct perf_event_header	header;
+		u64				time;
+		u64				id;
+		u64				stream_id;
+	} throttle_event = {
+		.header = {
+			.type = PERF_RECORD_THROTTLE,
+			.misc = 0,
+			.size = sizeof(throttle_event),
+		},
+		.time		= perf_clock(),
+		.id		= primary_event_id(event),
+		.stream_id	= event->id,
+	};
+
+	if (enable)
+		throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
+
+	ret = perf_output_begin(&handle, event, sizeof(throttle_event), 1, 0);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, throttle_event);
+	perf_output_end(&handle);
+}
+
+/*
+ * Generic event overflow handling, sampling.
+ */
+
+static int __perf_event_overflow(struct perf_event *event, int nmi,
+				   int throttle, struct perf_sample_data *data,
+				   struct pt_regs *regs)
+{
+	int events = atomic_read(&event->event_limit);
+	struct hw_perf_event *hwc = &event->hw;
+	int ret = 0;
+
+	throttle = (throttle && event->pmu->unthrottle != NULL);
+
+	if (!throttle) {
+		hwc->interrupts++;
+	} else {
+		if (hwc->interrupts != MAX_INTERRUPTS) {
+			hwc->interrupts++;
+			if (HZ * hwc->interrupts >
+					(u64)sysctl_perf_event_sample_rate) {
+				hwc->interrupts = MAX_INTERRUPTS;
+				perf_log_throttle(event, 0);
+				ret = 1;
+			}
+		} else {
+			/*
+			 * Keep re-disabling events even though on the previous
+			 * pass we disabled it - just in case we raced with a
+			 * sched-in and the event got enabled again:
+			 */
+			ret = 1;
+		}
+	}
+
+	if (event->attr.freq) {
+		u64 now = perf_clock();
+		s64 delta = now - hwc->freq_time_stamp;
+
+		hwc->freq_time_stamp = now;
+
+		if (delta > 0 && delta < 2*TICK_NSEC)
+			perf_adjust_period(event, delta, hwc->last_period);
+	}
+
+	/*
+	 * XXX event_limit might not quite work as expected on inherited
+	 * events
+	 */
+
+	event->pending_kill = POLL_IN;
+	if (events && atomic_dec_and_test(&event->event_limit)) {
+		ret = 1;
+		event->pending_kill = POLL_HUP;
+		if (nmi) {
+			event->pending_disable = 1;
+			perf_pending_queue(&event->pending,
+					   perf_pending_event);
+		} else
+			perf_event_disable(event);
+	}
+
+	if (event->overflow_handler)
+		event->overflow_handler(event, nmi, data, regs);
+	else
+		perf_event_output(event, nmi, data, regs);
+
+	return ret;
+}
+
+int perf_event_overflow(struct perf_event *event, int nmi,
+			  struct perf_sample_data *data,
+			  struct pt_regs *regs)
+{
+	return __perf_event_overflow(event, nmi, 1, data, regs);
+}
+
+/*
+ * Generic software event infrastructure
+ */
+
+/*
+ * We directly increment event->count and keep a second value in
+ * event->hw.period_left to count intervals. This period event
+ * is kept in the range [-sample_period, 0] so that we can use the
+ * sign as trigger.
+ */
+
+static u64 perf_swevent_set_period(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 period = hwc->last_period;
+	u64 nr, offset;
+	s64 old, val;
+
+	hwc->last_period = hwc->sample_period;
+
+again:
+	old = val = local64_read(&hwc->period_left);
+	if (val < 0)
+		return 0;
+
+	nr = div64_u64(period + val, period);
+	offset = nr * period;
+	val -= offset;
+	if (local64_cmpxchg(&hwc->period_left, old, val) != old)
+		goto again;
+
+	return nr;
+}
+
+static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
+				    int nmi, struct perf_sample_data *data,
+				    struct pt_regs *regs)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int throttle = 0;
+
+	data->period = event->hw.last_period;
+	if (!overflow)
+		overflow = perf_swevent_set_period(event);
+
+	if (hwc->interrupts == MAX_INTERRUPTS)
+		return;
+
+	for (; overflow; overflow--) {
+		if (__perf_event_overflow(event, nmi, throttle,
+					    data, regs)) {
+			/*
+			 * We inhibit the overflow from happening when
+			 * hwc->interrupts == MAX_INTERRUPTS.
+			 */
+			break;
+		}
+		throttle = 1;
+	}
+}
+
+static void perf_swevent_add(struct perf_event *event, u64 nr,
+			       int nmi, struct perf_sample_data *data,
+			       struct pt_regs *regs)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	local64_add(nr, &event->count);
+
+	if (!regs)
+		return;
+
+	if (!hwc->sample_period)
+		return;
+
+	if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
+		return perf_swevent_overflow(event, 1, nmi, data, regs);
+
+	if (local64_add_negative(nr, &hwc->period_left))
+		return;
+
+	perf_swevent_overflow(event, 0, nmi, data, regs);
+}
+
+static int perf_exclude_event(struct perf_event *event,
+			      struct pt_regs *regs)
+{
+	if (regs) {
+		if (event->attr.exclude_user && user_mode(regs))
+			return 1;
+
+		if (event->attr.exclude_kernel && !user_mode(regs))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int perf_swevent_match(struct perf_event *event,
+				enum perf_type_id type,
+				u32 event_id,
+				struct perf_sample_data *data,
+				struct pt_regs *regs)
+{
+	if (event->attr.type != type)
+		return 0;
+
+	if (event->attr.config != event_id)
+		return 0;
+
+	if (perf_exclude_event(event, regs))
+		return 0;
+
+	return 1;
+}
+
+static inline u64 swevent_hash(u64 type, u32 event_id)
+{
+	u64 val = event_id | (type << 32);
+
+	return hash_64(val, SWEVENT_HLIST_BITS);
+}
+
+static inline struct hlist_head *
+__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
+{
+	u64 hash = swevent_hash(type, event_id);
+
+	return &hlist->heads[hash];
+}
+
+/* For the read side: events when they trigger */
+static inline struct hlist_head *
+find_swevent_head_rcu(struct perf_cpu_context *ctx, u64 type, u32 event_id)
+{
+	struct swevent_hlist *hlist;
+
+	hlist = rcu_dereference(ctx->swevent_hlist);
+	if (!hlist)
+		return NULL;
+
+	return __find_swevent_head(hlist, type, event_id);
+}
+
+/* For the event head insertion and removal in the hlist */
+static inline struct hlist_head *
+find_swevent_head(struct perf_cpu_context *ctx, struct perf_event *event)
+{
+	struct swevent_hlist *hlist;
+	u32 event_id = event->attr.config;
+	u64 type = event->attr.type;
+
+	/*
+	 * Event scheduling is always serialized against hlist allocation
+	 * and release. Which makes the protected version suitable here.
+	 * The context lock guarantees that.
+	 */
+	hlist = rcu_dereference_protected(ctx->swevent_hlist,
+					  lockdep_is_held(&event->ctx->lock));
+	if (!hlist)
+		return NULL;
+
+	return __find_swevent_head(hlist, type, event_id);
+}
+
+static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
+				    u64 nr, int nmi,
+				    struct perf_sample_data *data,
+				    struct pt_regs *regs)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event *event;
+	struct hlist_node *node;
+	struct hlist_head *head;
+
+	cpuctx = &__get_cpu_var(perf_cpu_context);
+
+	rcu_read_lock();
+
+	head = find_swevent_head_rcu(cpuctx, type, event_id);
+
+	if (!head)
+		goto end;
+
+	hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+		if (perf_swevent_match(event, type, event_id, data, regs))
+			perf_swevent_add(event, nr, nmi, data, regs);
+	}
+end:
+	rcu_read_unlock();
+}
+
+int perf_swevent_get_recursion_context(void)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	int rctx;
+
+	if (in_nmi())
+		rctx = 3;
+	else if (in_irq())
+		rctx = 2;
+	else if (in_softirq())
+		rctx = 1;
+	else
+		rctx = 0;
+
+	if (cpuctx->recursion[rctx])
+		return -1;
+
+	cpuctx->recursion[rctx]++;
+	barrier();
+
+	return rctx;
+}
+EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
+
+void inline perf_swevent_put_recursion_context(int rctx)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	barrier();
+	cpuctx->recursion[rctx]--;
+}
+
+void __perf_sw_event(u32 event_id, u64 nr, int nmi,
+			    struct pt_regs *regs, u64 addr)
+{
+	struct perf_sample_data data;
+	int rctx;
+
+	preempt_disable_notrace();
+	rctx = perf_swevent_get_recursion_context();
+	if (rctx < 0)
+		return;
+
+	perf_sample_data_init(&data, addr);
+
+	do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
+
+	perf_swevent_put_recursion_context(rctx);
+	preempt_enable_notrace();
+}
+
+static void perf_swevent_read(struct perf_event *event)
+{
+}
+
+static int perf_swevent_enable(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct perf_cpu_context *cpuctx;
+	struct hlist_head *head;
+
+	cpuctx = &__get_cpu_var(perf_cpu_context);
+
+	if (hwc->sample_period) {
+		hwc->last_period = hwc->sample_period;
+		perf_swevent_set_period(event);
+	}
+
+	head = find_swevent_head(cpuctx, event);
+	if (WARN_ON_ONCE(!head))
+		return -EINVAL;
+
+	hlist_add_head_rcu(&event->hlist_entry, head);
+
+	return 0;
+}
+
+static void perf_swevent_disable(struct perf_event *event)
+{
+	hlist_del_rcu(&event->hlist_entry);
+}
+
+static void perf_swevent_void(struct perf_event *event)
+{
+}
+
+static int perf_swevent_int(struct perf_event *event)
+{
+	return 0;
+}
+
+static const struct pmu perf_ops_generic = {
+	.enable		= perf_swevent_enable,
+	.disable	= perf_swevent_disable,
+	.start		= perf_swevent_int,
+	.stop		= perf_swevent_void,
+	.read		= perf_swevent_read,
+	.unthrottle	= perf_swevent_void, /* hwc->interrupts already reset */
+};
+
+/*
+ * hrtimer based swevent callback
+ */
+
+static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
+{
+	enum hrtimer_restart ret = HRTIMER_RESTART;
+	struct perf_sample_data data;
+	struct pt_regs *regs;
+	struct perf_event *event;
+	u64 period;
+
+	event = container_of(hrtimer, struct perf_event, hw.hrtimer);
+	event->pmu->read(event);
+
+	perf_sample_data_init(&data, 0);
+	data.period = event->hw.last_period;
+	regs = get_irq_regs();
+
+	if (regs && !perf_exclude_event(event, regs)) {
+		if (!(event->attr.exclude_idle && current->pid == 0))
+			if (perf_event_overflow(event, 0, &data, regs))
+				ret = HRTIMER_NORESTART;
+	}
+
+	period = max_t(u64, 10000, event->hw.sample_period);
+	hrtimer_forward_now(hrtimer, ns_to_ktime(period));
+
+	return ret;
+}
+
+static void perf_swevent_start_hrtimer(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hwc->hrtimer.function = perf_swevent_hrtimer;
+	if (hwc->sample_period) {
+		u64 period;
+
+		if (hwc->remaining) {
+			if (hwc->remaining < 0)
+				period = 10000;
+			else
+				period = hwc->remaining;
+			hwc->remaining = 0;
+		} else {
+			period = max_t(u64, 10000, hwc->sample_period);
+		}
+		__hrtimer_start_range_ns(&hwc->hrtimer,
+				ns_to_ktime(period), 0,
+				HRTIMER_MODE_REL, 0);
+	}
+}
+
+static void perf_swevent_cancel_hrtimer(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (hwc->sample_period) {
+		ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
+		hwc->remaining = ktime_to_ns(remaining);
+
+		hrtimer_cancel(&hwc->hrtimer);
+	}
+}
+
+/*
+ * Software event: cpu wall time clock
+ */
+
+static void cpu_clock_perf_event_update(struct perf_event *event)
+{
+	int cpu = raw_smp_processor_id();
+	s64 prev;
+	u64 now;
+
+	now = cpu_clock(cpu);
+	prev = local64_xchg(&event->hw.prev_count, now);
+	local64_add(now - prev, &event->count);
+}
+
+static int cpu_clock_perf_event_enable(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int cpu = raw_smp_processor_id();
+
+	local64_set(&hwc->prev_count, cpu_clock(cpu));
+	perf_swevent_start_hrtimer(event);
+
+	return 0;
+}
+
+static void cpu_clock_perf_event_disable(struct perf_event *event)
+{
+	perf_swevent_cancel_hrtimer(event);
+	cpu_clock_perf_event_update(event);
+}
+
+static void cpu_clock_perf_event_read(struct perf_event *event)
+{
+	cpu_clock_perf_event_update(event);
+}
+
+static const struct pmu perf_ops_cpu_clock = {
+	.enable		= cpu_clock_perf_event_enable,
+	.disable	= cpu_clock_perf_event_disable,
+	.read		= cpu_clock_perf_event_read,
+};
+
+/*
+ * Software event: task time clock
+ */
+
+static void task_clock_perf_event_update(struct perf_event *event, u64 now)
+{
+	u64 prev;
+	s64 delta;
+
+	prev = local64_xchg(&event->hw.prev_count, now);
+	delta = now - prev;
+	local64_add(delta, &event->count);
+}
+
+static int task_clock_perf_event_enable(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 now;
+
+	now = event->ctx->time;
+
+	local64_set(&hwc->prev_count, now);
+
+	perf_swevent_start_hrtimer(event);
+
+	return 0;
+}
+
+static void task_clock_perf_event_disable(struct perf_event *event)
+{
+	perf_swevent_cancel_hrtimer(event);
+	task_clock_perf_event_update(event, event->ctx->time);
+
+}
+
+static void task_clock_perf_event_read(struct perf_event *event)
+{
+	u64 time;
+
+	if (!in_nmi()) {
+		update_context_time(event->ctx);
+		time = event->ctx->time;
+	} else {
+		u64 now = perf_clock();
+		u64 delta = now - event->ctx->timestamp;
+		time = event->ctx->time + delta;
+	}
+
+	task_clock_perf_event_update(event, time);
+}
+
+static const struct pmu perf_ops_task_clock = {
+	.enable		= task_clock_perf_event_enable,
+	.disable	= task_clock_perf_event_disable,
+	.read		= task_clock_perf_event_read,
+};
+
+/* Deref the hlist from the update side */
+static inline struct swevent_hlist *
+swevent_hlist_deref(struct perf_cpu_context *cpuctx)
+{
+	return rcu_dereference_protected(cpuctx->swevent_hlist,
+					 lockdep_is_held(&cpuctx->hlist_mutex));
+}
+
+static void swevent_hlist_release_rcu(struct rcu_head *rcu_head)
+{
+	struct swevent_hlist *hlist;
+
+	hlist = container_of(rcu_head, struct swevent_hlist, rcu_head);
+	kfree(hlist);
+}
+
+static void swevent_hlist_release(struct perf_cpu_context *cpuctx)
+{
+	struct swevent_hlist *hlist = swevent_hlist_deref(cpuctx);
+
+	if (!hlist)
+		return;
+
+	rcu_assign_pointer(cpuctx->swevent_hlist, NULL);
+	call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu);
+}
+
+static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
+{
+	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+
+	mutex_lock(&cpuctx->hlist_mutex);
+
+	if (!--cpuctx->hlist_refcount)
+		swevent_hlist_release(cpuctx);
+
+	mutex_unlock(&cpuctx->hlist_mutex);
+}
+
+static void swevent_hlist_put(struct perf_event *event)
+{
+	int cpu;
+
+	if (event->cpu != -1) {
+		swevent_hlist_put_cpu(event, event->cpu);
+		return;
+	}
+
+	for_each_possible_cpu(cpu)
+		swevent_hlist_put_cpu(event, cpu);
+}
+
+static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
+{
+	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+	int err = 0;
+
+	mutex_lock(&cpuctx->hlist_mutex);
+
+	if (!swevent_hlist_deref(cpuctx) && cpu_online(cpu)) {
+		struct swevent_hlist *hlist;
+
+		hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
+		if (!hlist) {
+			err = -ENOMEM;
+			goto exit;
+		}
+		rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
+	}
+	cpuctx->hlist_refcount++;
+ exit:
+	mutex_unlock(&cpuctx->hlist_mutex);
+
+	return err;
+}
+
+static int swevent_hlist_get(struct perf_event *event)
+{
+	int err;
+	int cpu, failed_cpu;
+
+	if (event->cpu != -1)
+		return swevent_hlist_get_cpu(event, event->cpu);
+
+	get_online_cpus();
+	for_each_possible_cpu(cpu) {
+		err = swevent_hlist_get_cpu(event, cpu);
+		if (err) {
+			failed_cpu = cpu;
+			goto fail;
+		}
+	}
+	put_online_cpus();
+
+	return 0;
+ fail:
+	for_each_possible_cpu(cpu) {
+		if (cpu == failed_cpu)
+			break;
+		swevent_hlist_put_cpu(event, cpu);
+	}
+
+	put_online_cpus();
+	return err;
+}
+
+#ifdef CONFIG_EVENT_TRACING
+
+static const struct pmu perf_ops_tracepoint = {
+	.enable		= perf_trace_enable,
+	.disable	= perf_trace_disable,
+	.start		= perf_swevent_int,
+	.stop		= perf_swevent_void,
+	.read		= perf_swevent_read,
+	.unthrottle	= perf_swevent_void,
+};
+
+static int perf_tp_filter_match(struct perf_event *event,
+				struct perf_sample_data *data)
+{
+	void *record = data->raw->data;
+
+	if (likely(!event->filter) || filter_match_preds(event->filter, record))
+		return 1;
+	return 0;
+}
+
+static int perf_tp_event_match(struct perf_event *event,
+				struct perf_sample_data *data,
+				struct pt_regs *regs)
+{
+	/*
+	 * All tracepoints are from kernel-space.
+	 */
+	if (event->attr.exclude_kernel)
+		return 0;
+
+	if (!perf_tp_filter_match(event, data))
+		return 0;
+
+	return 1;
+}
+
+void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
+		   struct pt_regs *regs, struct hlist_head *head, int rctx)
+{
+	struct perf_sample_data data;
+	struct perf_event *event;
+	struct hlist_node *node;
+
+	struct perf_raw_record raw = {
+		.size = entry_size,
+		.data = record,
+	};
+
+	perf_sample_data_init(&data, addr);
+	data.raw = &raw;
+
+	hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+		if (perf_tp_event_match(event, &data, regs))
+			perf_swevent_add(event, count, 1, &data, regs);
+	}
+
+	perf_swevent_put_recursion_context(rctx);
+}
+EXPORT_SYMBOL_GPL(perf_tp_event);
+
+static void tp_perf_event_destroy(struct perf_event *event)
+{
+	perf_trace_destroy(event);
+}
+
+static const struct pmu *tp_perf_event_init(struct perf_event *event)
+{
+	int err;
+
+	/*
+	 * Raw tracepoint data is a severe data leak, only allow root to
+	 * have these.
+	 */
+	if ((event->attr.sample_type & PERF_SAMPLE_RAW) &&
+			perf_paranoid_tracepoint_raw() &&
+			!capable(CAP_SYS_ADMIN))
+		return ERR_PTR(-EPERM);
+
+	err = perf_trace_init(event);
+	if (err)
+		return NULL;
+
+	event->destroy = tp_perf_event_destroy;
+
+	return &perf_ops_tracepoint;
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+	char *filter_str;
+	int ret;
+
+	if (event->attr.type != PERF_TYPE_TRACEPOINT)
+		return -EINVAL;
+
+	filter_str = strndup_user(arg, PAGE_SIZE);
+	if (IS_ERR(filter_str))
+		return PTR_ERR(filter_str);
+
+	ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
+
+	kfree(filter_str);
+	return ret;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+	ftrace_profile_free_filter(event);
+}
+
+#else
+
+static const struct pmu *tp_perf_event_init(struct perf_event *event)
+{
+	return NULL;
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+	return -ENOENT;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+}
+
+#endif /* CONFIG_EVENT_TRACING */
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+	release_bp_slot(event);
+}
+
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+	int err;
+
+	err = register_perf_hw_breakpoint(bp);
+	if (err)
+		return ERR_PTR(err);
+
+	bp->destroy = bp_perf_event_destroy;
+
+	return &perf_ops_bp;
+}
+
+void perf_bp_event(struct perf_event *bp, void *data)
+{
+	struct perf_sample_data sample;
+	struct pt_regs *regs = data;
+
+	perf_sample_data_init(&sample, bp->attr.bp_addr);
+
+	if (!perf_exclude_event(bp, regs))
+		perf_swevent_add(bp, 1, 1, &sample, regs);
+}
+#else
+static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+{
+	return NULL;
+}
+
+void perf_bp_event(struct perf_event *bp, void *regs)
+{
+}
+#endif
+
+atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
+
+static void sw_perf_event_destroy(struct perf_event *event)
+{
+	u64 event_id = event->attr.config;
+
+	WARN_ON(event->parent);
+
+	atomic_dec(&perf_swevent_enabled[event_id]);
+	swevent_hlist_put(event);
+}
+
+static const struct pmu *sw_perf_event_init(struct perf_event *event)
+{
+	const struct pmu *pmu = NULL;
+	u64 event_id = event->attr.config;
+
+	/*
+	 * Software events (currently) can't in general distinguish
+	 * between user, kernel and hypervisor events.
+	 * However, context switches and cpu migrations are considered
+	 * to be kernel events, and page faults are never hypervisor
+	 * events.
+	 */
+	switch (event_id) {
+	case PERF_COUNT_SW_CPU_CLOCK:
+		pmu = &perf_ops_cpu_clock;
+
+		break;
+	case PERF_COUNT_SW_TASK_CLOCK:
+		/*
+		 * If the user instantiates this as a per-cpu event,
+		 * use the cpu_clock event instead.
+		 */
+		if (event->ctx->task)
+			pmu = &perf_ops_task_clock;
+		else
+			pmu = &perf_ops_cpu_clock;
+
+		break;
+	case PERF_COUNT_SW_PAGE_FAULTS:
+	case PERF_COUNT_SW_PAGE_FAULTS_MIN:
+	case PERF_COUNT_SW_PAGE_FAULTS_MAJ:
+	case PERF_COUNT_SW_CONTEXT_SWITCHES:
+	case PERF_COUNT_SW_CPU_MIGRATIONS:
+	case PERF_COUNT_SW_ALIGNMENT_FAULTS:
+	case PERF_COUNT_SW_EMULATION_FAULTS:
+		if (!event->parent) {
+			int err;
+
+			err = swevent_hlist_get(event);
+			if (err)
+				return ERR_PTR(err);
+
+			atomic_inc(&perf_swevent_enabled[event_id]);
+			event->destroy = sw_perf_event_destroy;
+		}
+		pmu = &perf_ops_generic;
+		break;
+	}
+
+	return pmu;
+}
+
+/*
+ * Allocate and initialize a event structure
+ */
+static struct perf_event *
+perf_event_alloc(struct perf_event_attr *attr,
+		   int cpu,
+		   struct perf_event_context *ctx,
+		   struct perf_event *group_leader,
+		   struct perf_event *parent_event,
+		   perf_overflow_handler_t overflow_handler,
+		   gfp_t gfpflags)
+{
+	const struct pmu *pmu;
+	struct perf_event *event;
+	struct hw_perf_event *hwc;
+	long err;
+
+	event = kzalloc(sizeof(*event), gfpflags);
+	if (!event)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Single events are their own group leaders, with an
+	 * empty sibling list:
+	 */
+	if (!group_leader)
+		group_leader = event;
+
+	mutex_init(&event->child_mutex);
+	INIT_LIST_HEAD(&event->child_list);
+
+	INIT_LIST_HEAD(&event->group_entry);
+	INIT_LIST_HEAD(&event->event_entry);
+	INIT_LIST_HEAD(&event->sibling_list);
+	init_waitqueue_head(&event->waitq);
+
+	mutex_init(&event->mmap_mutex);
+
+	event->cpu		= cpu;
+	event->attr		= *attr;
+	event->group_leader	= group_leader;
+	event->pmu		= NULL;
+	event->ctx		= ctx;
+	event->oncpu		= -1;
+
+	event->parent		= parent_event;
+
+	event->ns		= get_pid_ns(current->nsproxy->pid_ns);
+	event->id		= atomic64_inc_return(&perf_event_id);
+
+	event->state		= PERF_EVENT_STATE_INACTIVE;
+
+	if (!overflow_handler && parent_event)
+		overflow_handler = parent_event->overflow_handler;
+	
+	event->overflow_handler	= overflow_handler;
+
+	if (attr->disabled)
+		event->state = PERF_EVENT_STATE_OFF;
+
+	pmu = NULL;
+
+	hwc = &event->hw;
+	hwc->sample_period = attr->sample_period;
+	if (attr->freq && attr->sample_freq)
+		hwc->sample_period = 1;
+	hwc->last_period = hwc->sample_period;
+
+	local64_set(&hwc->period_left, hwc->sample_period);
+
+	/*
+	 * we currently do not support PERF_FORMAT_GROUP on inherited events
+	 */
+	if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
+		goto done;
+
+	switch (attr->type) {
+	case PERF_TYPE_RAW:
+	case PERF_TYPE_HARDWARE:
+	case PERF_TYPE_HW_CACHE:
+		pmu = hw_perf_event_init(event);
+		break;
+
+	case PERF_TYPE_SOFTWARE:
+		pmu = sw_perf_event_init(event);
+		break;
+
+	case PERF_TYPE_TRACEPOINT:
+		pmu = tp_perf_event_init(event);
+		break;
+
+	case PERF_TYPE_BREAKPOINT:
+		pmu = bp_perf_event_init(event);
+		break;
+
+
+	default:
+		break;
+	}
+done:
+	err = 0;
+	if (!pmu)
+		err = -EINVAL;
+	else if (IS_ERR(pmu))
+		err = PTR_ERR(pmu);
+
+	if (err) {
+		if (event->ns)
+			put_pid_ns(event->ns);
+		kfree(event);
+		return ERR_PTR(err);
+	}
+
+	event->pmu = pmu;
+
+	if (!event->parent) {
+		atomic_inc(&nr_events);
+		if (event->attr.mmap || event->attr.mmap_data)
+			atomic_inc(&nr_mmap_events);
+		if (event->attr.comm)
+			atomic_inc(&nr_comm_events);
+		if (event->attr.task)
+			atomic_inc(&nr_task_events);
+	}
+
+	return event;
+}
+
+static int perf_copy_attr(struct perf_event_attr __user *uattr,
+			  struct perf_event_attr *attr)
+{
+	u32 size;
+	int ret;
+
+	if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
+		return -EFAULT;
+
+	/*
+	 * zero the full structure, so that a short copy will be nice.
+	 */
+	memset(attr, 0, sizeof(*attr));
+
+	ret = get_user(size, &uattr->size);
+	if (ret)
+		return ret;
+
+	if (size > PAGE_SIZE)	/* silly large */
+		goto err_size;
+
+	if (!size)		/* abi compat */
+		size = PERF_ATTR_SIZE_VER0;
+
+	if (size < PERF_ATTR_SIZE_VER0)
+		goto err_size;
+
+	/*
+	 * If we're handed a bigger struct than we know of,
+	 * ensure all the unknown bits are 0 - i.e. new
+	 * user-space does not rely on any kernel feature
+	 * extensions we dont know about yet.
+	 */
+	if (size > sizeof(*attr)) {
+		unsigned char __user *addr;
+		unsigned char __user *end;
+		unsigned char val;
+
+		addr = (void __user *)uattr + sizeof(*attr);
+		end  = (void __user *)uattr + size;
+
+		for (; addr < end; addr++) {
+			ret = get_user(val, addr);
+			if (ret)
+				return ret;
+			if (val)
+				goto err_size;
+		}
+		size = sizeof(*attr);
+	}
+
+	ret = copy_from_user(attr, uattr, size);
+	if (ret)
+		return -EFAULT;
+
+	/*
+	 * If the type exists, the corresponding creation will verify
+	 * the attr->config.
+	 */
+	if (attr->type >= PERF_TYPE_MAX)
+		return -EINVAL;
+
+	if (attr->__reserved_1)
+		return -EINVAL;
+
+	if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
+		return -EINVAL;
+
+	if (attr->read_format & ~(PERF_FORMAT_MAX-1))
+		return -EINVAL;
+
+out:
+	return ret;
+
+err_size:
+	put_user(sizeof(*attr), &uattr->size);
+	ret = -E2BIG;
+	goto out;
+}
+
+static int
+perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
+{
+	struct perf_buffer *buffer = NULL, *old_buffer = NULL;
+	int ret = -EINVAL;
+
+	if (!output_event)
+		goto set;
+
+	/* don't allow circular references */
+	if (event == output_event)
+		goto out;
+
+	/*
+	 * Don't allow cross-cpu buffers
+	 */
+	if (output_event->cpu != event->cpu)
+		goto out;
+
+	/*
+	 * If its not a per-cpu buffer, it must be the same task.
+	 */
+	if (output_event->cpu == -1 && output_event->ctx != event->ctx)
+		goto out;
+
+set:
+	mutex_lock(&event->mmap_mutex);
+	/* Can't redirect output if we've got an active mmap() */
+	if (atomic_read(&event->mmap_count))
+		goto unlock;
+
+	if (output_event) {
+		/* get the buffer we want to redirect to */
+		buffer = perf_buffer_get(output_event);
+		if (!buffer)
+			goto unlock;
+	}
+
+	old_buffer = event->buffer;
+	rcu_assign_pointer(event->buffer, buffer);
+	ret = 0;
+unlock:
+	mutex_unlock(&event->mmap_mutex);
+
+	if (old_buffer)
+		perf_buffer_put(old_buffer);
+out:
+	return ret;
+}
+
+/**
+ * sys_perf_event_open - open a performance event, associate it to a task/cpu
+ *
+ * @attr_uptr:	event_id type attributes for monitoring/sampling
+ * @pid:		target pid
+ * @cpu:		target cpu
+ * @group_fd:		group leader event fd
+ */
+SYSCALL_DEFINE5(perf_event_open,
+		struct perf_event_attr __user *, attr_uptr,
+		pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
+{
+	struct perf_event *event, *group_leader = NULL, *output_event = NULL;
+	struct perf_event_attr attr;
+	struct perf_event_context *ctx;
+	struct file *event_file = NULL;
+	struct file *group_file = NULL;
+	int event_fd;
+	int fput_needed = 0;
+	int err;
+
+	/* for future expandability... */
+	if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT))
+		return -EINVAL;
+
+	err = perf_copy_attr(attr_uptr, &attr);
+	if (err)
+		return err;
+
+	if (!attr.exclude_kernel) {
+		if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+			return -EACCES;
+	}
+
+	if (attr.freq) {
+		if (attr.sample_freq > sysctl_perf_event_sample_rate)
+			return -EINVAL;
+	}
+
+	event_fd = get_unused_fd_flags(O_RDWR);
+	if (event_fd < 0)
+		return event_fd;
+
+	/*
+	 * Get the target context (task or percpu):
+	 */
+	ctx = find_get_context(pid, cpu);
+	if (IS_ERR(ctx)) {
+		err = PTR_ERR(ctx);
+		goto err_fd;
+	}
+
+	if (group_fd != -1) {
+		group_leader = perf_fget_light(group_fd, &fput_needed);
+		if (IS_ERR(group_leader)) {
+			err = PTR_ERR(group_leader);
+			goto err_put_context;
+		}
+		group_file = group_leader->filp;
+		if (flags & PERF_FLAG_FD_OUTPUT)
+			output_event = group_leader;
+		if (flags & PERF_FLAG_FD_NO_GROUP)
+			group_leader = NULL;
+	}
+
+	/*
+	 * Look up the group leader (we will attach this event to it):
+	 */
+	if (group_leader) {
+		err = -EINVAL;
+
+		/*
+		 * Do not allow a recursive hierarchy (this new sibling
+		 * becoming part of another group-sibling):
+		 */
+		if (group_leader->group_leader != group_leader)
+			goto err_put_context;
+		/*
+		 * Do not allow to attach to a group in a different
+		 * task or CPU context:
+		 */
+		if (group_leader->ctx != ctx)
+			goto err_put_context;
+		/*
+		 * Only a group leader can be exclusive or pinned
+		 */
+		if (attr.exclusive || attr.pinned)
+			goto err_put_context;
+	}
+
+	event = perf_event_alloc(&attr, cpu, ctx, group_leader,
+				     NULL, NULL, GFP_KERNEL);
+	if (IS_ERR(event)) {
+		err = PTR_ERR(event);
+		goto err_put_context;
+	}
+
+	if (output_event) {
+		err = perf_event_set_output(event, output_event);
+		if (err)
+			goto err_free_put_context;
+	}
+
+	event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
+	if (IS_ERR(event_file)) {
+		err = PTR_ERR(event_file);
+		goto err_free_put_context;
+	}
+
+	event->filp = event_file;
+	WARN_ON_ONCE(ctx->parent_ctx);
+	mutex_lock(&ctx->mutex);
+	perf_install_in_context(ctx, event, cpu);
+	++ctx->generation;
+	mutex_unlock(&ctx->mutex);
+
+	event->owner = current;
+	get_task_struct(current);
+	mutex_lock(&current->perf_event_mutex);
+	list_add_tail(&event->owner_entry, &current->perf_event_list);
+	mutex_unlock(&current->perf_event_mutex);
+
+	/*
+	 * Drop the reference on the group_event after placing the
+	 * new event on the sibling_list. This ensures destruction
+	 * of the group leader will find the pointer to itself in
+	 * perf_group_detach().
+	 */
+	fput_light(group_file, fput_needed);
+	fd_install(event_fd, event_file);
+	return event_fd;
+
+err_free_put_context:
+	free_event(event);
+err_put_context:
+	fput_light(group_file, fput_needed);
+	put_ctx(ctx);
+err_fd:
+	put_unused_fd(event_fd);
+	return err;
+}
+
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @pid: task to profile
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+				 pid_t pid,
+				 perf_overflow_handler_t overflow_handler)
+{
+	struct perf_event *event;
+	struct perf_event_context *ctx;
+	int err;
+
+	/*
+	 * Get the target context (task or percpu):
+	 */
+
+	ctx = find_get_context(pid, cpu);
+	if (IS_ERR(ctx)) {
+		err = PTR_ERR(ctx);
+		goto err_exit;
+	}
+
+	event = perf_event_alloc(attr, cpu, ctx, NULL,
+				 NULL, overflow_handler, GFP_KERNEL);
+	if (IS_ERR(event)) {
+		err = PTR_ERR(event);
+		goto err_put_context;
+	}
+
+	event->filp = NULL;
+	WARN_ON_ONCE(ctx->parent_ctx);
+	mutex_lock(&ctx->mutex);
+	perf_install_in_context(ctx, event, cpu);
+	++ctx->generation;
+	mutex_unlock(&ctx->mutex);
+
+	event->owner = current;
+	get_task_struct(current);
+	mutex_lock(&current->perf_event_mutex);
+	list_add_tail(&event->owner_entry, &current->perf_event_list);
+	mutex_unlock(&current->perf_event_mutex);
+
+	return event;
+
+ err_put_context:
+	put_ctx(ctx);
+ err_exit:
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
+/*
+ * inherit a event from parent task to child task:
+ */
+static struct perf_event *
+inherit_event(struct perf_event *parent_event,
+	      struct task_struct *parent,
+	      struct perf_event_context *parent_ctx,
+	      struct task_struct *child,
+	      struct perf_event *group_leader,
+	      struct perf_event_context *child_ctx)
+{
+	struct perf_event *child_event;
+
+	/*
+	 * Instead of creating recursive hierarchies of events,
+	 * we link inherited events back to the original parent,
+	 * which has a filp for sure, which we use as the reference
+	 * count:
+	 */
+	if (parent_event->parent)
+		parent_event = parent_event->parent;
+
+	child_event = perf_event_alloc(&parent_event->attr,
+					   parent_event->cpu, child_ctx,
+					   group_leader, parent_event,
+					   NULL, GFP_KERNEL);
+	if (IS_ERR(child_event))
+		return child_event;
+	get_ctx(child_ctx);
+
+	/*
+	 * Make the child state follow the state of the parent event,
+	 * not its attr.disabled bit.  We hold the parent's mutex,
+	 * so we won't race with perf_event_{en, dis}able_family.
+	 */
+	if (parent_event->state >= PERF_EVENT_STATE_INACTIVE)
+		child_event->state = PERF_EVENT_STATE_INACTIVE;
+	else
+		child_event->state = PERF_EVENT_STATE_OFF;
+
+	if (parent_event->attr.freq) {
+		u64 sample_period = parent_event->hw.sample_period;
+		struct hw_perf_event *hwc = &child_event->hw;
+
+		hwc->sample_period = sample_period;
+		hwc->last_period   = sample_period;
+
+		local64_set(&hwc->period_left, sample_period);
+	}
+
+	child_event->overflow_handler = parent_event->overflow_handler;
+
+	/*
+	 * Link it up in the child's context:
+	 */
+	add_event_to_ctx(child_event, child_ctx);
+
+	/*
+	 * Get a reference to the parent filp - we will fput it
+	 * when the child event exits. This is safe to do because
+	 * we are in the parent and we know that the filp still
+	 * exists and has a nonzero count:
+	 */
+	atomic_long_inc(&parent_event->filp->f_count);
+
+	/*
+	 * Link this into the parent event's child list
+	 */
+	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+	mutex_lock(&parent_event->child_mutex);
+	list_add_tail(&child_event->child_list, &parent_event->child_list);
+	mutex_unlock(&parent_event->child_mutex);
+
+	return child_event;
+}
+
+static int inherit_group(struct perf_event *parent_event,
+	      struct task_struct *parent,
+	      struct perf_event_context *parent_ctx,
+	      struct task_struct *child,
+	      struct perf_event_context *child_ctx)
+{
+	struct perf_event *leader;
+	struct perf_event *sub;
+	struct perf_event *child_ctr;
+
+	leader = inherit_event(parent_event, parent, parent_ctx,
+				 child, NULL, child_ctx);
+	if (IS_ERR(leader))
+		return PTR_ERR(leader);
+	list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
+		child_ctr = inherit_event(sub, parent, parent_ctx,
+					    child, leader, child_ctx);
+		if (IS_ERR(child_ctr))
+			return PTR_ERR(child_ctr);
+	}
+	return 0;
+}
+
+static void sync_child_event(struct perf_event *child_event,
+			       struct task_struct *child)
+{
+	struct perf_event *parent_event = child_event->parent;
+	u64 child_val;
+
+	if (child_event->attr.inherit_stat)
+		perf_event_read_event(child_event, child);
+
+	child_val = perf_event_count(child_event);
+
+	/*
+	 * Add back the child's count to the parent's count:
+	 */
+	atomic64_add(child_val, &parent_event->child_count);
+	atomic64_add(child_event->total_time_enabled,
+		     &parent_event->child_total_time_enabled);
+	atomic64_add(child_event->total_time_running,
+		     &parent_event->child_total_time_running);
+
+	/*
+	 * Remove this event from the parent's list
+	 */
+	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+	mutex_lock(&parent_event->child_mutex);
+	list_del_init(&child_event->child_list);
+	mutex_unlock(&parent_event->child_mutex);
+
+	/*
+	 * Release the parent event, if this was the last
+	 * reference to it.
+	 */
+	fput(parent_event->filp);
+}
+
+static void
+__perf_event_exit_task(struct perf_event *child_event,
+			 struct perf_event_context *child_ctx,
+			 struct task_struct *child)
+{
+	struct perf_event *parent_event;
+
+	perf_event_remove_from_context(child_event);
+
+	parent_event = child_event->parent;
+	/*
+	 * It can happen that parent exits first, and has events
+	 * that are still around due to the child reference. These
+	 * events need to be zapped - but otherwise linger.
+	 */
+	if (parent_event) {
+		sync_child_event(child_event, child);
+		free_event(child_event);
+	}
+}
+
+/*
+ * When a child task exits, feed back event values to parent events.
+ */
+void perf_event_exit_task(struct task_struct *child)
+{
+	struct perf_event *child_event, *tmp;
+	struct perf_event_context *child_ctx;
+	unsigned long flags;
+
+	if (likely(!child->perf_event_ctxp)) {
+		perf_event_task(child, NULL, 0);
+		return;
+	}
+
+	local_irq_save(flags);
+	/*
+	 * We can't reschedule here because interrupts are disabled,
+	 * and either child is current or it is a task that can't be
+	 * scheduled, so we are now safe from rescheduling changing
+	 * our context.
+	 */
+	child_ctx = child->perf_event_ctxp;
+	__perf_event_task_sched_out(child_ctx);
+
+	/*
+	 * Take the context lock here so that if find_get_context is
+	 * reading child->perf_event_ctxp, we wait until it has
+	 * incremented the context's refcount before we do put_ctx below.
+	 */
+	raw_spin_lock(&child_ctx->lock);
+	child->perf_event_ctxp = NULL;
+	/*
+	 * If this context is a clone; unclone it so it can't get
+	 * swapped to another process while we're removing all
+	 * the events from it.
+	 */
+	unclone_ctx(child_ctx);
+	update_context_time(child_ctx);
+	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+	/*
+	 * Report the task dead after unscheduling the events so that we
+	 * won't get any samples after PERF_RECORD_EXIT. We can however still
+	 * get a few PERF_RECORD_READ events.
+	 */
+	perf_event_task(child, child_ctx, 0);
+
+	/*
+	 * We can recurse on the same lock type through:
+	 *
+	 *   __perf_event_exit_task()
+	 *     sync_child_event()
+	 *       fput(parent_event->filp)
+	 *         perf_release()
+	 *           mutex_lock(&ctx->mutex)
+	 *
+	 * But since its the parent context it won't be the same instance.
+	 */
+	mutex_lock(&child_ctx->mutex);
+
+again:
+	list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
+				 group_entry)
+		__perf_event_exit_task(child_event, child_ctx, child);
+
+	list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
+				 group_entry)
+		__perf_event_exit_task(child_event, child_ctx, child);
+
+	/*
+	 * If the last event was a group event, it will have appended all
+	 * its siblings to the list, but we obtained 'tmp' before that which
+	 * will still point to the list head terminating the iteration.
+	 */
+	if (!list_empty(&child_ctx->pinned_groups) ||
+	    !list_empty(&child_ctx->flexible_groups))
+		goto again;
+
+	mutex_unlock(&child_ctx->mutex);
+
+	put_ctx(child_ctx);
+}
+
+static void perf_free_event(struct perf_event *event,
+			    struct perf_event_context *ctx)
+{
+	struct perf_event *parent = event->parent;
+
+	if (WARN_ON_ONCE(!parent))
+		return;
+
+	mutex_lock(&parent->child_mutex);
+	list_del_init(&event->child_list);
+	mutex_unlock(&parent->child_mutex);
+
+	fput(parent->filp);
+
+	perf_group_detach(event);
+	list_del_event(event, ctx);
+	free_event(event);
+}
+
+/*
+ * free an unexposed, unused context as created by inheritance by
+ * init_task below, used by fork() in case of fail.
+ */
+void perf_event_free_task(struct task_struct *task)
+{
+	struct perf_event_context *ctx = task->perf_event_ctxp;
+	struct perf_event *event, *tmp;
+
+	if (!ctx)
+		return;
+
+	mutex_lock(&ctx->mutex);
+again:
+	list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
+		perf_free_event(event, ctx);
+
+	list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
+				 group_entry)
+		perf_free_event(event, ctx);
+
+	if (!list_empty(&ctx->pinned_groups) ||
+	    !list_empty(&ctx->flexible_groups))
+		goto again;
+
+	mutex_unlock(&ctx->mutex);
+
+	put_ctx(ctx);
+}
+
+static int
+inherit_task_group(struct perf_event *event, struct task_struct *parent,
+		   struct perf_event_context *parent_ctx,
+		   struct task_struct *child,
+		   int *inherited_all)
+{
+	int ret;
+	struct perf_event_context *child_ctx = child->perf_event_ctxp;
+
+	if (!event->attr.inherit) {
+		*inherited_all = 0;
+		return 0;
+	}
+
+	if (!child_ctx) {
+		/*
+		 * This is executed from the parent task context, so
+		 * inherit events that have been marked for cloning.
+		 * First allocate and initialize a context for the
+		 * child.
+		 */
+
+		child_ctx = kzalloc(sizeof(struct perf_event_context),
+				    GFP_KERNEL);
+		if (!child_ctx)
+			return -ENOMEM;
+
+		__perf_event_init_context(child_ctx, child);
+		child->perf_event_ctxp = child_ctx;
+		get_task_struct(child);
+	}
+
+	ret = inherit_group(event, parent, parent_ctx,
+			    child, child_ctx);
+
+	if (ret)
+		*inherited_all = 0;
+
+	return ret;
+}
+
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_task(struct task_struct *child)
+{
+	struct perf_event_context *child_ctx, *parent_ctx;
+	struct perf_event_context *cloned_ctx;
+	struct perf_event *event;
+	struct task_struct *parent = current;
+	int inherited_all = 1;
+	int ret = 0;
+
+	child->perf_event_ctxp = NULL;
+
+	mutex_init(&child->perf_event_mutex);
+	INIT_LIST_HEAD(&child->perf_event_list);
+
+	if (likely(!parent->perf_event_ctxp))
+		return 0;
+
+	/*
+	 * If the parent's context is a clone, pin it so it won't get
+	 * swapped under us.
+	 */
+	parent_ctx = perf_pin_task_context(parent);
+
+	/*
+	 * No need to check if parent_ctx != NULL here; since we saw
+	 * it non-NULL earlier, the only reason for it to become NULL
+	 * is if we exit, and since we're currently in the middle of
+	 * a fork we can't be exiting at the same time.
+	 */
+
+	/*
+	 * Lock the parent list. No need to lock the child - not PID
+	 * hashed yet and not running, so nobody can access it.
+	 */
+	mutex_lock(&parent_ctx->mutex);
+
+	/*
+	 * We dont have to disable NMIs - we are only looking at
+	 * the list, not manipulating it:
+	 */
+	list_for_each_entry(event, &parent_ctx->pinned_groups, group_entry) {
+		ret = inherit_task_group(event, parent, parent_ctx, child,
+					 &inherited_all);
+		if (ret)
+			break;
+	}
+
+	list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
+		ret = inherit_task_group(event, parent, parent_ctx, child,
+					 &inherited_all);
+		if (ret)
+			break;
+	}
+
+	child_ctx = child->perf_event_ctxp;
+
+	if (child_ctx && inherited_all) {
+		/*
+		 * Mark the child context as a clone of the parent
+		 * context, or of whatever the parent is a clone of.
+		 * Note that if the parent is a clone, it could get
+		 * uncloned at any point, but that doesn't matter
+		 * because the list of events and the generation
+		 * count can't have changed since we took the mutex.
+		 */
+		cloned_ctx = rcu_dereference(parent_ctx->parent_ctx);
+		if (cloned_ctx) {
+			child_ctx->parent_ctx = cloned_ctx;
+			child_ctx->parent_gen = parent_ctx->parent_gen;
+		} else {
+			child_ctx->parent_ctx = parent_ctx;
+			child_ctx->parent_gen = parent_ctx->generation;
+		}
+		get_ctx(child_ctx->parent_ctx);
+	}
+
+	mutex_unlock(&parent_ctx->mutex);
+
+	perf_unpin_context(parent_ctx);
+
+	return ret;
+}
+
+static void __init perf_event_init_all_cpus(void)
+{
+	int cpu;
+	struct perf_cpu_context *cpuctx;
+
+	for_each_possible_cpu(cpu) {
+		cpuctx = &per_cpu(perf_cpu_context, cpu);
+		mutex_init(&cpuctx->hlist_mutex);
+		__perf_event_init_context(&cpuctx->ctx, NULL);
+	}
+}
+
+static void __cpuinit perf_event_init_cpu(int cpu)
+{
+	struct perf_cpu_context *cpuctx;
+
+	cpuctx = &per_cpu(perf_cpu_context, cpu);
+
+	spin_lock(&perf_resource_lock);
+	cpuctx->max_pertask = perf_max_events - perf_reserved_percpu;
+	spin_unlock(&perf_resource_lock);
+
+	mutex_lock(&cpuctx->hlist_mutex);
+	if (cpuctx->hlist_refcount > 0) {
+		struct swevent_hlist *hlist;
+
+		hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
+		WARN_ON_ONCE(!hlist);
+		rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
+	}
+	mutex_unlock(&cpuctx->hlist_mutex);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void __perf_event_exit_cpu(void *info)
+{
+	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+	struct perf_event_context *ctx = &cpuctx->ctx;
+	struct perf_event *event, *tmp;
+
+	list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
+		__perf_event_remove_from_context(event);
+	list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
+		__perf_event_remove_from_context(event);
+}
+static void perf_event_exit_cpu(int cpu)
+{
+	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+	struct perf_event_context *ctx = &cpuctx->ctx;
+
+	mutex_lock(&cpuctx->hlist_mutex);
+	swevent_hlist_release(cpuctx);
+	mutex_unlock(&cpuctx->hlist_mutex);
+
+	mutex_lock(&ctx->mutex);
+	smp_call_function_single(cpu, __perf_event_exit_cpu, NULL, 1);
+	mutex_unlock(&ctx->mutex);
+}
+#else
+static inline void perf_event_exit_cpu(int cpu) { }
+#endif
+
+static int __cpuinit
+perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (long)hcpu;
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+
+	case CPU_UP_PREPARE:
+	case CPU_DOWN_FAILED:
+		perf_event_init_cpu(cpu);
+		break;
+
+	case CPU_UP_CANCELED:
+	case CPU_DOWN_PREPARE:
+		perf_event_exit_cpu(cpu);
+		break;
+
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+/*
+ * This has to have a higher priority than migration_notifier in sched.c.
+ */
+static struct notifier_block __cpuinitdata perf_cpu_nb = {
+	.notifier_call		= perf_cpu_notify,
+	.priority		= 20,
+};
+
+void __init perf_event_init(void)
+{
+	perf_event_init_all_cpus();
+	perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
+			(void *)(long)smp_processor_id());
+	perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
+			(void *)(long)smp_processor_id());
+	register_cpu_notifier(&perf_cpu_nb);
+}
+
+static ssize_t perf_show_reserve_percpu(struct sysdev_class *class,
+					struct sysdev_class_attribute *attr,
+					char *buf)
+{
+	return sprintf(buf, "%d\n", perf_reserved_percpu);
+}
+
+static ssize_t
+perf_set_reserve_percpu(struct sysdev_class *class,
+			struct sysdev_class_attribute *attr,
+			const char *buf,
+			size_t count)
+{
+	struct perf_cpu_context *cpuctx;
+	unsigned long val;
+	int err, cpu, mpt;
+
+	err = strict_strtoul(buf, 10, &val);
+	if (err)
+		return err;
+	if (val > perf_max_events)
+		return -EINVAL;
+
+	spin_lock(&perf_resource_lock);
+	perf_reserved_percpu = val;
+	for_each_online_cpu(cpu) {
+		cpuctx = &per_cpu(perf_cpu_context, cpu);
+		raw_spin_lock_irq(&cpuctx->ctx.lock);
+		mpt = min(perf_max_events - cpuctx->ctx.nr_events,
+			  perf_max_events - perf_reserved_percpu);
+		cpuctx->max_pertask = mpt;
+		raw_spin_unlock_irq(&cpuctx->ctx.lock);
+	}
+	spin_unlock(&perf_resource_lock);
+
+	return count;
+}
+
+static ssize_t perf_show_overcommit(struct sysdev_class *class,
+				    struct sysdev_class_attribute *attr,
+				    char *buf)
+{
+	return sprintf(buf, "%d\n", perf_overcommit);
+}
+
+static ssize_t
+perf_set_overcommit(struct sysdev_class *class,
+		    struct sysdev_class_attribute *attr,
+		    const char *buf, size_t count)
+{
+	unsigned long val;
+	int err;
+
+	err = strict_strtoul(buf, 10, &val);
+	if (err)
+		return err;
+	if (val > 1)
+		return -EINVAL;
+
+	spin_lock(&perf_resource_lock);
+	perf_overcommit = val;
+	spin_unlock(&perf_resource_lock);
+
+	return count;
+}
+
+static SYSDEV_CLASS_ATTR(
+				reserve_percpu,
+				0644,
+				perf_show_reserve_percpu,
+				perf_set_reserve_percpu
+			);
+
+static SYSDEV_CLASS_ATTR(
+				overcommit,
+				0644,
+				perf_show_overcommit,
+				perf_set_overcommit
+			);
+
+static struct attribute *perfclass_attrs[] = {
+	&attr_reserve_percpu.attr,
+	&attr_overcommit.attr,
+	NULL
+};
+
+static struct attribute_group perfclass_attr_group = {
+	.attrs			= perfclass_attrs,
+	.name			= "perf_events",
+};
+
+static int __init perf_event_sysfs_init(void)
+{
+	return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
+				  &perfclass_attr_group);
+}
+device_initcall(perf_event_sysfs_init);
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
deleted file mode 100644
index b98bed3..0000000
--- a/kernel/perf_event.c
+++ /dev/null
@@ -1,5895 +0,0 @@
-/*
- * Performance events core code:
- *
- *  Copyright (C) 2008 Thomas Gleixner <tglx@xxxxxxxxxxxxx>
- *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
- *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@xxxxxxxxxx>
- *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@xxxxxxxxxxx>
- *
- * For licensing details see kernel-base/COPYING
- */
-
-#include <linux/fs.h>
-#include <linux/mm.h>
-#include <linux/cpu.h>
-#include <linux/smp.h>
-#include <linux/file.h>
-#include <linux/poll.h>
-#include <linux/slab.h>
-#include <linux/hash.h>
-#include <linux/sysfs.h>
-#include <linux/dcache.h>
-#include <linux/percpu.h>
-#include <linux/ptrace.h>
-#include <linux/vmstat.h>
-#include <linux/vmalloc.h>
-#include <linux/hardirq.h>
-#include <linux/rculist.h>
-#include <linux/uaccess.h>
-#include <linux/syscalls.h>
-#include <linux/anon_inodes.h>
-#include <linux/kernel_stat.h>
-#include <linux/perf_event.h>
-#include <linux/ftrace_event.h>
-#include <linux/hw_breakpoint.h>
-
-#include <asm/irq_regs.h>
-
-/*
- * Each CPU has a list of per CPU events:
- */
-static DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
-
-int perf_max_events __read_mostly = 1;
-static int perf_reserved_percpu __read_mostly;
-static int perf_overcommit __read_mostly = 1;
-
-static atomic_t nr_events __read_mostly;
-static atomic_t nr_mmap_events __read_mostly;
-static atomic_t nr_comm_events __read_mostly;
-static atomic_t nr_task_events __read_mostly;
-
-/*
- * perf event paranoia level:
- *  -1 - not paranoid at all
- *   0 - disallow raw tracepoint access for unpriv
- *   1 - disallow cpu events for unpriv
- *   2 - disallow kernel profiling for unpriv
- */
-int sysctl_perf_event_paranoid __read_mostly = 1;
-
-int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
-
-/*
- * max perf event sample rate
- */
-int sysctl_perf_event_sample_rate __read_mostly = 100000;
-
-static atomic64_t perf_event_id;
-
-/*
- * Lock for (sysadmin-configurable) event reservations:
- */
-static DEFINE_SPINLOCK(perf_resource_lock);
-
-/*
- * Architecture provided APIs - weak aliases:
- */
-extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
-{
-	return NULL;
-}
-
-void __weak hw_perf_disable(void)		{ barrier(); }
-void __weak hw_perf_enable(void)		{ barrier(); }
-
-void __weak perf_event_print_debug(void)	{ }
-
-static DEFINE_PER_CPU(int, perf_disable_count);
-
-void perf_disable(void)
-{
-	if (!__get_cpu_var(perf_disable_count)++)
-		hw_perf_disable();
-}
-
-void perf_enable(void)
-{
-	if (!--__get_cpu_var(perf_disable_count))
-		hw_perf_enable();
-}
-
-static void get_ctx(struct perf_event_context *ctx)
-{
-	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
-}
-
-static void free_ctx(struct rcu_head *head)
-{
-	struct perf_event_context *ctx;
-
-	ctx = container_of(head, struct perf_event_context, rcu_head);
-	kfree(ctx);
-}
-
-static void put_ctx(struct perf_event_context *ctx)
-{
-	if (atomic_dec_and_test(&ctx->refcount)) {
-		if (ctx->parent_ctx)
-			put_ctx(ctx->parent_ctx);
-		if (ctx->task)
-			put_task_struct(ctx->task);
-		call_rcu(&ctx->rcu_head, free_ctx);
-	}
-}
-
-static void unclone_ctx(struct perf_event_context *ctx)
-{
-	if (ctx->parent_ctx) {
-		put_ctx(ctx->parent_ctx);
-		ctx->parent_ctx = NULL;
-	}
-}
-
-/*
- * If we inherit events we want to return the parent event id
- * to userspace.
- */
-static u64 primary_event_id(struct perf_event *event)
-{
-	u64 id = event->id;
-
-	if (event->parent)
-		id = event->parent->id;
-
-	return id;
-}
-
-/*
- * Get the perf_event_context for a task and lock it.
- * This has to cope with with the fact that until it is locked,
- * the context could get moved to another task.
- */
-static struct perf_event_context *
-perf_lock_task_context(struct task_struct *task, unsigned long *flags)
-{
-	struct perf_event_context *ctx;
-
-	rcu_read_lock();
- retry:
-	ctx = rcu_dereference(task->perf_event_ctxp);
-	if (ctx) {
-		/*
-		 * If this context is a clone of another, it might
-		 * get swapped for another underneath us by
-		 * perf_event_task_sched_out, though the
-		 * rcu_read_lock() protects us from any context
-		 * getting freed.  Lock the context and check if it
-		 * got swapped before we could get the lock, and retry
-		 * if so.  If we locked the right context, then it
-		 * can't get swapped on us any more.
-		 */
-		raw_spin_lock_irqsave(&ctx->lock, *flags);
-		if (ctx != rcu_dereference(task->perf_event_ctxp)) {
-			raw_spin_unlock_irqrestore(&ctx->lock, *flags);
-			goto retry;
-		}
-
-		if (!atomic_inc_not_zero(&ctx->refcount)) {
-			raw_spin_unlock_irqrestore(&ctx->lock, *flags);
-			ctx = NULL;
-		}
-	}
-	rcu_read_unlock();
-	return ctx;
-}
-
-/*
- * Get the context for a task and increment its pin_count so it
- * can't get swapped to another task.  This also increments its
- * reference count so that the context can't get freed.
- */
-static struct perf_event_context *perf_pin_task_context(struct task_struct *task)
-{
-	struct perf_event_context *ctx;
-	unsigned long flags;
-
-	ctx = perf_lock_task_context(task, &flags);
-	if (ctx) {
-		++ctx->pin_count;
-		raw_spin_unlock_irqrestore(&ctx->lock, flags);
-	}
-	return ctx;
-}
-
-static void perf_unpin_context(struct perf_event_context *ctx)
-{
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&ctx->lock, flags);
-	--ctx->pin_count;
-	raw_spin_unlock_irqrestore(&ctx->lock, flags);
-	put_ctx(ctx);
-}
-
-static inline u64 perf_clock(void)
-{
-	return local_clock();
-}
-
-/*
- * Update the record of the current time in a context.
- */
-static void update_context_time(struct perf_event_context *ctx)
-{
-	u64 now = perf_clock();
-
-	ctx->time += now - ctx->timestamp;
-	ctx->timestamp = now;
-}
-
-/*
- * Update the total_time_enabled and total_time_running fields for a event.
- */
-static void update_event_times(struct perf_event *event)
-{
-	struct perf_event_context *ctx = event->ctx;
-	u64 run_end;
-
-	if (event->state < PERF_EVENT_STATE_INACTIVE ||
-	    event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
-		return;
-
-	if (ctx->is_active)
-		run_end = ctx->time;
-	else
-		run_end = event->tstamp_stopped;
-
-	event->total_time_enabled = run_end - event->tstamp_enabled;
-
-	if (event->state == PERF_EVENT_STATE_INACTIVE)
-		run_end = event->tstamp_stopped;
-	else
-		run_end = ctx->time;
-
-	event->total_time_running = run_end - event->tstamp_running;
-}
-
-/*
- * Update total_time_enabled and total_time_running for all events in a group.
- */
-static void update_group_times(struct perf_event *leader)
-{
-	struct perf_event *event;
-
-	update_event_times(leader);
-	list_for_each_entry(event, &leader->sibling_list, group_entry)
-		update_event_times(event);
-}
-
-static struct list_head *
-ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
-{
-	if (event->attr.pinned)
-		return &ctx->pinned_groups;
-	else
-		return &ctx->flexible_groups;
-}
-
-/*
- * Add a event from the lists for its context.
- * Must be called with ctx->mutex and ctx->lock held.
- */
-static void
-list_add_event(struct perf_event *event, struct perf_event_context *ctx)
-{
-	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
-	event->attach_state |= PERF_ATTACH_CONTEXT;
-
-	/*
-	 * If we're a stand alone event or group leader, we go to the context
-	 * list, group events are kept attached to the group so that
-	 * perf_group_detach can, at all times, locate all siblings.
-	 */
-	if (event->group_leader == event) {
-		struct list_head *list;
-
-		if (is_software_event(event))
-			event->group_flags |= PERF_GROUP_SOFTWARE;
-
-		list = ctx_group_list(event, ctx);
-		list_add_tail(&event->group_entry, list);
-	}
-
-	list_add_rcu(&event->event_entry, &ctx->event_list);
-	ctx->nr_events++;
-	if (event->attr.inherit_stat)
-		ctx->nr_stat++;
-}
-
-static void perf_group_attach(struct perf_event *event)
-{
-	struct perf_event *group_leader = event->group_leader;
-
-	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_GROUP);
-	event->attach_state |= PERF_ATTACH_GROUP;
-
-	if (group_leader == event)
-		return;
-
-	if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
-			!is_software_event(event))
-		group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
-
-	list_add_tail(&event->group_entry, &group_leader->sibling_list);
-	group_leader->nr_siblings++;
-}
-
-/*
- * Remove a event from the lists for its context.
- * Must be called with ctx->mutex and ctx->lock held.
- */
-static void
-list_del_event(struct perf_event *event, struct perf_event_context *ctx)
-{
-	/*
-	 * We can have double detach due to exit/hot-unplug + close.
-	 */
-	if (!(event->attach_state & PERF_ATTACH_CONTEXT))
-		return;
-
-	event->attach_state &= ~PERF_ATTACH_CONTEXT;
-
-	ctx->nr_events--;
-	if (event->attr.inherit_stat)
-		ctx->nr_stat--;
-
-	list_del_rcu(&event->event_entry);
-
-	if (event->group_leader == event)
-		list_del_init(&event->group_entry);
-
-	update_group_times(event);
-
-	/*
-	 * If event was in error state, then keep it
-	 * that way, otherwise bogus counts will be
-	 * returned on read(). The only way to get out
-	 * of error state is by explicit re-enabling
-	 * of the event
-	 */
-	if (event->state > PERF_EVENT_STATE_OFF)
-		event->state = PERF_EVENT_STATE_OFF;
-}
-
-static void perf_group_detach(struct perf_event *event)
-{
-	struct perf_event *sibling, *tmp;
-	struct list_head *list = NULL;
-
-	/*
-	 * We can have double detach due to exit/hot-unplug + close.
-	 */
-	if (!(event->attach_state & PERF_ATTACH_GROUP))
-		return;
-
-	event->attach_state &= ~PERF_ATTACH_GROUP;
-
-	/*
-	 * If this is a sibling, remove it from its group.
-	 */
-	if (event->group_leader != event) {
-		list_del_init(&event->group_entry);
-		event->group_leader->nr_siblings--;
-		return;
-	}
-
-	if (!list_empty(&event->group_entry))
-		list = &event->group_entry;
-
-	/*
-	 * If this was a group event with sibling events then
-	 * upgrade the siblings to singleton events by adding them
-	 * to whatever list we are on.
-	 */
-	list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
-		if (list)
-			list_move_tail(&sibling->group_entry, list);
-		sibling->group_leader = sibling;
-
-		/* Inherit group flags from the previous leader */
-		sibling->group_flags = event->group_flags;
-	}
-}
-
-static inline int
-event_filter_match(struct perf_event *event)
-{
-	return event->cpu == -1 || event->cpu == smp_processor_id();
-}
-
-static void
-event_sched_out(struct perf_event *event,
-		  struct perf_cpu_context *cpuctx,
-		  struct perf_event_context *ctx)
-{
-	u64 delta;
-	/*
-	 * An event which could not be activated because of
-	 * filter mismatch still needs to have its timings
-	 * maintained, otherwise bogus information is return
-	 * via read() for time_enabled, time_running:
-	 */
-	if (event->state == PERF_EVENT_STATE_INACTIVE
-	    && !event_filter_match(event)) {
-		delta = ctx->time - event->tstamp_stopped;
-		event->tstamp_running += delta;
-		event->tstamp_stopped = ctx->time;
-	}
-
-	if (event->state != PERF_EVENT_STATE_ACTIVE)
-		return;
-
-	event->state = PERF_EVENT_STATE_INACTIVE;
-	if (event->pending_disable) {
-		event->pending_disable = 0;
-		event->state = PERF_EVENT_STATE_OFF;
-	}
-	event->tstamp_stopped = ctx->time;
-	event->pmu->disable(event);
-	event->oncpu = -1;
-
-	if (!is_software_event(event))
-		cpuctx->active_oncpu--;
-	ctx->nr_active--;
-	if (event->attr.exclusive || !cpuctx->active_oncpu)
-		cpuctx->exclusive = 0;
-}
-
-static void
-group_sched_out(struct perf_event *group_event,
-		struct perf_cpu_context *cpuctx,
-		struct perf_event_context *ctx)
-{
-	struct perf_event *event;
-	int state = group_event->state;
-
-	event_sched_out(group_event, cpuctx, ctx);
-
-	/*
-	 * Schedule out siblings (if any):
-	 */
-	list_for_each_entry(event, &group_event->sibling_list, group_entry)
-		event_sched_out(event, cpuctx, ctx);
-
-	if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive)
-		cpuctx->exclusive = 0;
-}
-
-/*
- * Cross CPU call to remove a performance event
- *
- * We disable the event on the hardware level first. After that we
- * remove it from the context list.
- */
-static void __perf_event_remove_from_context(void *info)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
-
-	/*
-	 * If this is a task context, we need to check whether it is
-	 * the current task context of this cpu. If not it has been
-	 * scheduled out before the smp call arrived.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx)
-		return;
-
-	raw_spin_lock(&ctx->lock);
-	/*
-	 * Protect the list operation against NMI by disabling the
-	 * events on a global level.
-	 */
-	perf_disable();
-
-	event_sched_out(event, cpuctx, ctx);
-
-	list_del_event(event, ctx);
-
-	if (!ctx->task) {
-		/*
-		 * Allow more per task events with respect to the
-		 * reservation:
-		 */
-		cpuctx->max_pertask =
-			min(perf_max_events - ctx->nr_events,
-			    perf_max_events - perf_reserved_percpu);
-	}
-
-	perf_enable();
-	raw_spin_unlock(&ctx->lock);
-}
-
-
-/*
- * Remove the event from a task's (or a CPU's) list of events.
- *
- * Must be called with ctx->mutex held.
- *
- * CPU events are removed with a smp call. For task events we only
- * call when the task is on a CPU.
- *
- * If event->ctx is a cloned context, callers must make sure that
- * every task struct that event->ctx->task could possibly point to
- * remains valid.  This is OK when called from perf_release since
- * that only calls us on the top-level context, which can't be a clone.
- * When called from perf_event_exit_task, it's OK because the
- * context has been detached from its task.
- */
-static void perf_event_remove_from_context(struct perf_event *event)
-{
-	struct perf_event_context *ctx = event->ctx;
-	struct task_struct *task = ctx->task;
-
-	if (!task) {
-		/*
-		 * Per cpu events are removed via an smp call and
-		 * the removal is always successful.
-		 */
-		smp_call_function_single(event->cpu,
-					 __perf_event_remove_from_context,
-					 event, 1);
-		return;
-	}
-
-retry:
-	task_oncpu_function_call(task, __perf_event_remove_from_context,
-				 event);
-
-	raw_spin_lock_irq(&ctx->lock);
-	/*
-	 * If the context is active we need to retry the smp call.
-	 */
-	if (ctx->nr_active && !list_empty(&event->group_entry)) {
-		raw_spin_unlock_irq(&ctx->lock);
-		goto retry;
-	}
-
-	/*
-	 * The lock prevents that this context is scheduled in so we
-	 * can remove the event safely, if the call above did not
-	 * succeed.
-	 */
-	if (!list_empty(&event->group_entry))
-		list_del_event(event, ctx);
-	raw_spin_unlock_irq(&ctx->lock);
-}
-
-/*
- * Cross CPU call to disable a performance event
- */
-static void __perf_event_disable(void *info)
-{
-	struct perf_event *event = info;
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = event->ctx;
-
-	/*
-	 * If this is a per-task event, need to check whether this
-	 * event's task is the current task on this cpu.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx)
-		return;
-
-	raw_spin_lock(&ctx->lock);
-
-	/*
-	 * If the event is on, turn it off.
-	 * If it is in error state, leave it in error state.
-	 */
-	if (event->state >= PERF_EVENT_STATE_INACTIVE) {
-		update_context_time(ctx);
-		update_group_times(event);
-		if (event == event->group_leader)
-			group_sched_out(event, cpuctx, ctx);
-		else
-			event_sched_out(event, cpuctx, ctx);
-		event->state = PERF_EVENT_STATE_OFF;
-	}
-
-	raw_spin_unlock(&ctx->lock);
-}
-
-/*
- * Disable a event.
- *
- * If event->ctx is a cloned context, callers must make sure that
- * every task struct that event->ctx->task could possibly point to
- * remains valid.  This condition is satisifed when called through
- * perf_event_for_each_child or perf_event_for_each because they
- * hold the top-level event's child_mutex, so any descendant that
- * goes to exit will block in sync_child_event.
- * When called from perf_pending_event it's OK because event->ctx
- * is the current context on this CPU and preemption is disabled,
- * hence we can't get into perf_event_task_sched_out for this context.
- */
-void perf_event_disable(struct perf_event *event)
-{
-	struct perf_event_context *ctx = event->ctx;
-	struct task_struct *task = ctx->task;
-
-	if (!task) {
-		/*
-		 * Disable the event on the cpu that it's on
-		 */
-		smp_call_function_single(event->cpu, __perf_event_disable,
-					 event, 1);
-		return;
-	}
-
- retry:
-	task_oncpu_function_call(task, __perf_event_disable, event);
-
-	raw_spin_lock_irq(&ctx->lock);
-	/*
-	 * If the event is still active, we need to retry the cross-call.
-	 */
-	if (event->state == PERF_EVENT_STATE_ACTIVE) {
-		raw_spin_unlock_irq(&ctx->lock);
-		goto retry;
-	}
-
-	/*
-	 * Since we have the lock this context can't be scheduled
-	 * in, so we can change the state safely.
-	 */
-	if (event->state == PERF_EVENT_STATE_INACTIVE) {
-		update_group_times(event);
-		event->state = PERF_EVENT_STATE_OFF;
-	}
-
-	raw_spin_unlock_irq(&ctx->lock);
-}
-
-static int
-event_sched_in(struct perf_event *event,
-		 struct perf_cpu_context *cpuctx,
-		 struct perf_event_context *ctx)
-{
-	if (event->state <= PERF_EVENT_STATE_OFF)
-		return 0;
-
-	event->state = PERF_EVENT_STATE_ACTIVE;
-	event->oncpu = smp_processor_id();
-	/*
-	 * The new state must be visible before we turn it on in the hardware:
-	 */
-	smp_wmb();
-
-	if (event->pmu->enable(event)) {
-		event->state = PERF_EVENT_STATE_INACTIVE;
-		event->oncpu = -1;
-		return -EAGAIN;
-	}
-
-	event->tstamp_running += ctx->time - event->tstamp_stopped;
-
-	if (!is_software_event(event))
-		cpuctx->active_oncpu++;
-	ctx->nr_active++;
-
-	if (event->attr.exclusive)
-		cpuctx->exclusive = 1;
-
-	return 0;
-}
-
-static int
-group_sched_in(struct perf_event *group_event,
-	       struct perf_cpu_context *cpuctx,
-	       struct perf_event_context *ctx)
-{
-	struct perf_event *event, *partial_group = NULL;
-	const struct pmu *pmu = group_event->pmu;
-	bool txn = false;
-
-	if (group_event->state == PERF_EVENT_STATE_OFF)
-		return 0;
-
-	/* Check if group transaction availabe */
-	if (pmu->start_txn)
-		txn = true;
-
-	if (txn)
-		pmu->start_txn(pmu);
-
-	if (event_sched_in(group_event, cpuctx, ctx)) {
-		if (txn)
-			pmu->cancel_txn(pmu);
-		return -EAGAIN;
-	}
-
-	/*
-	 * Schedule in siblings as one group (if any):
-	 */
-	list_for_each_entry(event, &group_event->sibling_list, group_entry) {
-		if (event_sched_in(event, cpuctx, ctx)) {
-			partial_group = event;
-			goto group_error;
-		}
-	}
-
-	if (!txn || !pmu->commit_txn(pmu))
-		return 0;
-
-group_error:
-	/*
-	 * Groups can be scheduled in as one unit only, so undo any
-	 * partial group before returning:
-	 */
-	list_for_each_entry(event, &group_event->sibling_list, group_entry) {
-		if (event == partial_group)
-			break;
-		event_sched_out(event, cpuctx, ctx);
-	}
-	event_sched_out(group_event, cpuctx, ctx);
-
-	if (txn)
-		pmu->cancel_txn(pmu);
-
-	return -EAGAIN;
-}
-
-/*
- * Work out whether we can put this event group on the CPU now.
- */
-static int group_can_go_on(struct perf_event *event,
-			   struct perf_cpu_context *cpuctx,
-			   int can_add_hw)
-{
-	/*
-	 * Groups consisting entirely of software events can always go on.
-	 */
-	if (event->group_flags & PERF_GROUP_SOFTWARE)
-		return 1;
-	/*
-	 * If an exclusive group is already on, no other hardware
-	 * events can go on.
-	 */
-	if (cpuctx->exclusive)
-		return 0;
-	/*
-	 * If this group is exclusive and there are already
-	 * events on the CPU, it can't go on.
-	 */
-	if (event->attr.exclusive && cpuctx->active_oncpu)
-		return 0;
-	/*
-	 * Otherwise, try to add it if all previous groups were able
-	 * to go on.
-	 */
-	return can_add_hw;
-}
-
-static void add_event_to_ctx(struct perf_event *event,
-			       struct perf_event_context *ctx)
-{
-	list_add_event(event, ctx);
-	perf_group_attach(event);
-	event->tstamp_enabled = ctx->time;
-	event->tstamp_running = ctx->time;
-	event->tstamp_stopped = ctx->time;
-}
-
-/*
- * Cross CPU call to install and enable a performance event
- *
- * Must be called with ctx->mutex held
- */
-static void __perf_install_in_context(void *info)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_event *leader = event->group_leader;
-	int err;
-
-	/*
-	 * If this is a task context, we need to check whether it is
-	 * the current task context of this cpu. If not it has been
-	 * scheduled out before the smp call arrived.
-	 * Or possibly this is the right context but it isn't
-	 * on this cpu because it had no events.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx) {
-		if (cpuctx->task_ctx || ctx->task != current)
-			return;
-		cpuctx->task_ctx = ctx;
-	}
-
-	raw_spin_lock(&ctx->lock);
-	ctx->is_active = 1;
-	update_context_time(ctx);
-
-	/*
-	 * Protect the list operation against NMI by disabling the
-	 * events on a global level. NOP for non NMI based events.
-	 */
-	perf_disable();
-
-	add_event_to_ctx(event, ctx);
-
-	if (event->cpu != -1 && event->cpu != smp_processor_id())
-		goto unlock;
-
-	/*
-	 * Don't put the event on if it is disabled or if
-	 * it is in a group and the group isn't on.
-	 */
-	if (event->state != PERF_EVENT_STATE_INACTIVE ||
-	    (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
-		goto unlock;
-
-	/*
-	 * An exclusive event can't go on if there are already active
-	 * hardware events, and no hardware event can go on if there
-	 * is already an exclusive event on.
-	 */
-	if (!group_can_go_on(event, cpuctx, 1))
-		err = -EEXIST;
-	else
-		err = event_sched_in(event, cpuctx, ctx);
-
-	if (err) {
-		/*
-		 * This event couldn't go on.  If it is in a group
-		 * then we have to pull the whole group off.
-		 * If the event group is pinned then put it in error state.
-		 */
-		if (leader != event)
-			group_sched_out(leader, cpuctx, ctx);
-		if (leader->attr.pinned) {
-			update_group_times(leader);
-			leader->state = PERF_EVENT_STATE_ERROR;
-		}
-	}
-
-	if (!err && !ctx->task && cpuctx->max_pertask)
-		cpuctx->max_pertask--;
-
- unlock:
-	perf_enable();
-
-	raw_spin_unlock(&ctx->lock);
-}
-
-/*
- * Attach a performance event to a context
- *
- * First we add the event to the list with the hardware enable bit
- * in event->hw_config cleared.
- *
- * If the event is attached to a task which is on a CPU we use a smp
- * call to enable it in the task context. The task might have been
- * scheduled away, but we check this in the smp call again.
- *
- * Must be called with ctx->mutex held.
- */
-static void
-perf_install_in_context(struct perf_event_context *ctx,
-			struct perf_event *event,
-			int cpu)
-{
-	struct task_struct *task = ctx->task;
-
-	if (!task) {
-		/*
-		 * Per cpu events are installed via an smp call and
-		 * the install is always successful.
-		 */
-		smp_call_function_single(cpu, __perf_install_in_context,
-					 event, 1);
-		return;
-	}
-
-retry:
-	task_oncpu_function_call(task, __perf_install_in_context,
-				 event);
-
-	raw_spin_lock_irq(&ctx->lock);
-	/*
-	 * we need to retry the smp call.
-	 */
-	if (ctx->is_active && list_empty(&event->group_entry)) {
-		raw_spin_unlock_irq(&ctx->lock);
-		goto retry;
-	}
-
-	/*
-	 * The lock prevents that this context is scheduled in so we
-	 * can add the event safely, if it the call above did not
-	 * succeed.
-	 */
-	if (list_empty(&event->group_entry))
-		add_event_to_ctx(event, ctx);
-	raw_spin_unlock_irq(&ctx->lock);
-}
-
-/*
- * Put a event into inactive state and update time fields.
- * Enabling the leader of a group effectively enables all
- * the group members that aren't explicitly disabled, so we
- * have to update their ->tstamp_enabled also.
- * Note: this works for group members as well as group leaders
- * since the non-leader members' sibling_lists will be empty.
- */
-static void __perf_event_mark_enabled(struct perf_event *event,
-					struct perf_event_context *ctx)
-{
-	struct perf_event *sub;
-
-	event->state = PERF_EVENT_STATE_INACTIVE;
-	event->tstamp_enabled = ctx->time - event->total_time_enabled;
-	list_for_each_entry(sub, &event->sibling_list, group_entry)
-		if (sub->state >= PERF_EVENT_STATE_INACTIVE)
-			sub->tstamp_enabled =
-				ctx->time - sub->total_time_enabled;
-}
-
-/*
- * Cross CPU call to enable a performance event
- */
-static void __perf_event_enable(void *info)
-{
-	struct perf_event *event = info;
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_event *leader = event->group_leader;
-	int err;
-
-	/*
-	 * If this is a per-task event, need to check whether this
-	 * event's task is the current task on this cpu.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx) {
-		if (cpuctx->task_ctx || ctx->task != current)
-			return;
-		cpuctx->task_ctx = ctx;
-	}
-
-	raw_spin_lock(&ctx->lock);
-	ctx->is_active = 1;
-	update_context_time(ctx);
-
-	if (event->state >= PERF_EVENT_STATE_INACTIVE)
-		goto unlock;
-	__perf_event_mark_enabled(event, ctx);
-
-	if (event->cpu != -1 && event->cpu != smp_processor_id())
-		goto unlock;
-
-	/*
-	 * If the event is in a group and isn't the group leader,
-	 * then don't put it on unless the group is on.
-	 */
-	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
-		goto unlock;
-
-	if (!group_can_go_on(event, cpuctx, 1)) {
-		err = -EEXIST;
-	} else {
-		perf_disable();
-		if (event == leader)
-			err = group_sched_in(event, cpuctx, ctx);
-		else
-			err = event_sched_in(event, cpuctx, ctx);
-		perf_enable();
-	}
-
-	if (err) {
-		/*
-		 * If this event can't go on and it's part of a
-		 * group, then the whole group has to come off.
-		 */
-		if (leader != event)
-			group_sched_out(leader, cpuctx, ctx);
-		if (leader->attr.pinned) {
-			update_group_times(leader);
-			leader->state = PERF_EVENT_STATE_ERROR;
-		}
-	}
-
- unlock:
-	raw_spin_unlock(&ctx->lock);
-}
-
-/*
- * Enable a event.
- *
- * If event->ctx is a cloned context, callers must make sure that
- * every task struct that event->ctx->task could possibly point to
- * remains valid.  This condition is satisfied when called through
- * perf_event_for_each_child or perf_event_for_each as described
- * for perf_event_disable.
- */
-void perf_event_enable(struct perf_event *event)
-{
-	struct perf_event_context *ctx = event->ctx;
-	struct task_struct *task = ctx->task;
-
-	if (!task) {
-		/*
-		 * Enable the event on the cpu that it's on
-		 */
-		smp_call_function_single(event->cpu, __perf_event_enable,
-					 event, 1);
-		return;
-	}
-
-	raw_spin_lock_irq(&ctx->lock);
-	if (event->state >= PERF_EVENT_STATE_INACTIVE)
-		goto out;
-
-	/*
-	 * If the event is in error state, clear that first.
-	 * That way, if we see the event in error state below, we
-	 * know that it has gone back into error state, as distinct
-	 * from the task having been scheduled away before the
-	 * cross-call arrived.
-	 */
-	if (event->state == PERF_EVENT_STATE_ERROR)
-		event->state = PERF_EVENT_STATE_OFF;
-
- retry:
-	raw_spin_unlock_irq(&ctx->lock);
-	task_oncpu_function_call(task, __perf_event_enable, event);
-
-	raw_spin_lock_irq(&ctx->lock);
-
-	/*
-	 * If the context is active and the event is still off,
-	 * we need to retry the cross-call.
-	 */
-	if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF)
-		goto retry;
-
-	/*
-	 * Since we have the lock this context can't be scheduled
-	 * in, so we can change the state safely.
-	 */
-	if (event->state == PERF_EVENT_STATE_OFF)
-		__perf_event_mark_enabled(event, ctx);
-
- out:
-	raw_spin_unlock_irq(&ctx->lock);
-}
-
-static int perf_event_refresh(struct perf_event *event, int refresh)
-{
-	/*
-	 * not supported on inherited events
-	 */
-	if (event->attr.inherit)
-		return -EINVAL;
-
-	atomic_add(refresh, &event->event_limit);
-	perf_event_enable(event);
-
-	return 0;
-}
-
-enum event_type_t {
-	EVENT_FLEXIBLE = 0x1,
-	EVENT_PINNED = 0x2,
-	EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
-};
-
-static void ctx_sched_out(struct perf_event_context *ctx,
-			  struct perf_cpu_context *cpuctx,
-			  enum event_type_t event_type)
-{
-	struct perf_event *event;
-
-	raw_spin_lock(&ctx->lock);
-	ctx->is_active = 0;
-	if (likely(!ctx->nr_events))
-		goto out;
-	update_context_time(ctx);
-
-	perf_disable();
-	if (!ctx->nr_active)
-		goto out_enable;
-
-	if (event_type & EVENT_PINNED)
-		list_for_each_entry(event, &ctx->pinned_groups, group_entry)
-			group_sched_out(event, cpuctx, ctx);
-
-	if (event_type & EVENT_FLEXIBLE)
-		list_for_each_entry(event, &ctx->flexible_groups, group_entry)
-			group_sched_out(event, cpuctx, ctx);
-
- out_enable:
-	perf_enable();
- out:
-	raw_spin_unlock(&ctx->lock);
-}
-
-/*
- * Test whether two contexts are equivalent, i.e. whether they
- * have both been cloned from the same version of the same context
- * and they both have the same number of enabled events.
- * If the number of enabled events is the same, then the set
- * of enabled events should be the same, because these are both
- * inherited contexts, therefore we can't access individual events
- * in them directly with an fd; we can only enable/disable all
- * events via prctl, or enable/disable all events in a family
- * via ioctl, which will have the same effect on both contexts.
- */
-static int context_equiv(struct perf_event_context *ctx1,
-			 struct perf_event_context *ctx2)
-{
-	return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
-		&& ctx1->parent_gen == ctx2->parent_gen
-		&& !ctx1->pin_count && !ctx2->pin_count;
-}
-
-static void __perf_event_sync_stat(struct perf_event *event,
-				     struct perf_event *next_event)
-{
-	u64 value;
-
-	if (!event->attr.inherit_stat)
-		return;
-
-	/*
-	 * Update the event value, we cannot use perf_event_read()
-	 * because we're in the middle of a context switch and have IRQs
-	 * disabled, which upsets smp_call_function_single(), however
-	 * we know the event must be on the current CPU, therefore we
-	 * don't need to use it.
-	 */
-	switch (event->state) {
-	case PERF_EVENT_STATE_ACTIVE:
-		event->pmu->read(event);
-		/* fall-through */
-
-	case PERF_EVENT_STATE_INACTIVE:
-		update_event_times(event);
-		break;
-
-	default:
-		break;
-	}
-
-	/*
-	 * In order to keep per-task stats reliable we need to flip the event
-	 * values when we flip the contexts.
-	 */
-	value = local64_read(&next_event->count);
-	value = local64_xchg(&event->count, value);
-	local64_set(&next_event->count, value);
-
-	swap(event->total_time_enabled, next_event->total_time_enabled);
-	swap(event->total_time_running, next_event->total_time_running);
-
-	/*
-	 * Since we swizzled the values, update the user visible data too.
-	 */
-	perf_event_update_userpage(event);
-	perf_event_update_userpage(next_event);
-}
-
-#define list_next_entry(pos, member) \
-	list_entry(pos->member.next, typeof(*pos), member)
-
-static void perf_event_sync_stat(struct perf_event_context *ctx,
-				   struct perf_event_context *next_ctx)
-{
-	struct perf_event *event, *next_event;
-
-	if (!ctx->nr_stat)
-		return;
-
-	update_context_time(ctx);
-
-	event = list_first_entry(&ctx->event_list,
-				   struct perf_event, event_entry);
-
-	next_event = list_first_entry(&next_ctx->event_list,
-					struct perf_event, event_entry);
-
-	while (&event->event_entry != &ctx->event_list &&
-	       &next_event->event_entry != &next_ctx->event_list) {
-
-		__perf_event_sync_stat(event, next_event);
-
-		event = list_next_entry(event, event_entry);
-		next_event = list_next_entry(next_event, event_entry);
-	}
-}
-
-/*
- * Called from scheduler to remove the events of the current task,
- * with interrupts disabled.
- *
- * We stop each event and update the event value in event->count.
- *
- * This does not protect us against NMI, but disable()
- * sets the disabled bit in the control field of event _before_
- * accessing the event control register. If a NMI hits, then it will
- * not restart the event.
- */
-void perf_event_task_sched_out(struct task_struct *task,
-				 struct task_struct *next)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = task->perf_event_ctxp;
-	struct perf_event_context *next_ctx;
-	struct perf_event_context *parent;
-	int do_switch = 1;
-
-	perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
-
-	if (likely(!ctx || !cpuctx->task_ctx))
-		return;
-
-	rcu_read_lock();
-	parent = rcu_dereference(ctx->parent_ctx);
-	next_ctx = next->perf_event_ctxp;
-	if (parent && next_ctx &&
-	    rcu_dereference(next_ctx->parent_ctx) == parent) {
-		/*
-		 * Looks like the two contexts are clones, so we might be
-		 * able to optimize the context switch.  We lock both
-		 * contexts and check that they are clones under the
-		 * lock (including re-checking that neither has been
-		 * uncloned in the meantime).  It doesn't matter which
-		 * order we take the locks because no other cpu could
-		 * be trying to lock both of these tasks.
-		 */
-		raw_spin_lock(&ctx->lock);
-		raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
-		if (context_equiv(ctx, next_ctx)) {
-			/*
-			 * XXX do we need a memory barrier of sorts
-			 * wrt to rcu_dereference() of perf_event_ctxp
-			 */
-			task->perf_event_ctxp = next_ctx;
-			next->perf_event_ctxp = ctx;
-			ctx->task = next;
-			next_ctx->task = task;
-			do_switch = 0;
-
-			perf_event_sync_stat(ctx, next_ctx);
-		}
-		raw_spin_unlock(&next_ctx->lock);
-		raw_spin_unlock(&ctx->lock);
-	}
-	rcu_read_unlock();
-
-	if (do_switch) {
-		ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-		cpuctx->task_ctx = NULL;
-	}
-}
-
-static void task_ctx_sched_out(struct perf_event_context *ctx,
-			       enum event_type_t event_type)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-
-	if (!cpuctx->task_ctx)
-		return;
-
-	if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
-		return;
-
-	ctx_sched_out(ctx, cpuctx, event_type);
-	cpuctx->task_ctx = NULL;
-}
-
-/*
- * Called with IRQs disabled
- */
-static void __perf_event_task_sched_out(struct perf_event_context *ctx)
-{
-	task_ctx_sched_out(ctx, EVENT_ALL);
-}
-
-/*
- * Called with IRQs disabled
- */
-static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
-			      enum event_type_t event_type)
-{
-	ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
-}
-
-static void
-ctx_pinned_sched_in(struct perf_event_context *ctx,
-		    struct perf_cpu_context *cpuctx)
-{
-	struct perf_event *event;
-
-	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
-		if (event->state <= PERF_EVENT_STATE_OFF)
-			continue;
-		if (event->cpu != -1 && event->cpu != smp_processor_id())
-			continue;
-
-		if (group_can_go_on(event, cpuctx, 1))
-			group_sched_in(event, cpuctx, ctx);
-
-		/*
-		 * If this pinned group hasn't been scheduled,
-		 * put it in error state.
-		 */
-		if (event->state == PERF_EVENT_STATE_INACTIVE) {
-			update_group_times(event);
-			event->state = PERF_EVENT_STATE_ERROR;
-		}
-	}
-}
-
-static void
-ctx_flexible_sched_in(struct perf_event_context *ctx,
-		      struct perf_cpu_context *cpuctx)
-{
-	struct perf_event *event;
-	int can_add_hw = 1;
-
-	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
-		/* Ignore events in OFF or ERROR state */
-		if (event->state <= PERF_EVENT_STATE_OFF)
-			continue;
-		/*
-		 * Listen to the 'cpu' scheduling filter constraint
-		 * of events:
-		 */
-		if (event->cpu != -1 && event->cpu != smp_processor_id())
-			continue;
-
-		if (group_can_go_on(event, cpuctx, can_add_hw))
-			if (group_sched_in(event, cpuctx, ctx))
-				can_add_hw = 0;
-	}
-}
-
-static void
-ctx_sched_in(struct perf_event_context *ctx,
-	     struct perf_cpu_context *cpuctx,
-	     enum event_type_t event_type)
-{
-	raw_spin_lock(&ctx->lock);
-	ctx->is_active = 1;
-	if (likely(!ctx->nr_events))
-		goto out;
-
-	ctx->timestamp = perf_clock();
-
-	perf_disable();
-
-	/*
-	 * First go through the list and put on any pinned groups
-	 * in order to give them the best chance of going on.
-	 */
-	if (event_type & EVENT_PINNED)
-		ctx_pinned_sched_in(ctx, cpuctx);
-
-	/* Then walk through the lower prio flexible groups */
-	if (event_type & EVENT_FLEXIBLE)
-		ctx_flexible_sched_in(ctx, cpuctx);
-
-	perf_enable();
- out:
-	raw_spin_unlock(&ctx->lock);
-}
-
-static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
-			     enum event_type_t event_type)
-{
-	struct perf_event_context *ctx = &cpuctx->ctx;
-
-	ctx_sched_in(ctx, cpuctx, event_type);
-}
-
-static void task_ctx_sched_in(struct task_struct *task,
-			      enum event_type_t event_type)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = task->perf_event_ctxp;
-
-	if (likely(!ctx))
-		return;
-	if (cpuctx->task_ctx == ctx)
-		return;
-	ctx_sched_in(ctx, cpuctx, event_type);
-	cpuctx->task_ctx = ctx;
-}
-/*
- * Called from scheduler to add the events of the current task
- * with interrupts disabled.
- *
- * We restore the event value and then enable it.
- *
- * This does not protect us against NMI, but enable()
- * sets the enabled bit in the control field of event _before_
- * accessing the event control register. If a NMI hits, then it will
- * keep the event running.
- */
-void perf_event_task_sched_in(struct task_struct *task)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = task->perf_event_ctxp;
-
-	if (likely(!ctx))
-		return;
-
-	if (cpuctx->task_ctx == ctx)
-		return;
-
-	perf_disable();
-
-	/*
-	 * We want to keep the following priority order:
-	 * cpu pinned (that don't need to move), task pinned,
-	 * cpu flexible, task flexible.
-	 */
-	cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
-
-	ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
-	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
-	ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
-
-	cpuctx->task_ctx = ctx;
-
-	perf_enable();
-}
-
-#define MAX_INTERRUPTS (~0ULL)
-
-static void perf_log_throttle(struct perf_event *event, int enable);
-
-static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
-{
-	u64 frequency = event->attr.sample_freq;
-	u64 sec = NSEC_PER_SEC;
-	u64 divisor, dividend;
-
-	int count_fls, nsec_fls, frequency_fls, sec_fls;
-
-	count_fls = fls64(count);
-	nsec_fls = fls64(nsec);
-	frequency_fls = fls64(frequency);
-	sec_fls = 30;
-
-	/*
-	 * We got @count in @nsec, with a target of sample_freq HZ
-	 * the target period becomes:
-	 *
-	 *             @count * 10^9
-	 * period = -------------------
-	 *          @nsec * sample_freq
-	 *
-	 */
-
-	/*
-	 * Reduce accuracy by one bit such that @a and @b converge
-	 * to a similar magnitude.
-	 */
-#define REDUCE_FLS(a, b) 		\
-do {					\
-	if (a##_fls > b##_fls) {	\
-		a >>= 1;		\
-		a##_fls--;		\
-	} else {			\
-		b >>= 1;		\
-		b##_fls--;		\
-	}				\
-} while (0)
-
-	/*
-	 * Reduce accuracy until either term fits in a u64, then proceed with
-	 * the other, so that finally we can do a u64/u64 division.
-	 */
-	while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
-		REDUCE_FLS(nsec, frequency);
-		REDUCE_FLS(sec, count);
-	}
-
-	if (count_fls + sec_fls > 64) {
-		divisor = nsec * frequency;
-
-		while (count_fls + sec_fls > 64) {
-			REDUCE_FLS(count, sec);
-			divisor >>= 1;
-		}
-
-		dividend = count * sec;
-	} else {
-		dividend = count * sec;
-
-		while (nsec_fls + frequency_fls > 64) {
-			REDUCE_FLS(nsec, frequency);
-			dividend >>= 1;
-		}
-
-		divisor = nsec * frequency;
-	}
-
-	if (!divisor)
-		return dividend;
-
-	return div64_u64(dividend, divisor);
-}
-
-static void perf_event_stop(struct perf_event *event)
-{
-	if (!event->pmu->stop)
-		return event->pmu->disable(event);
-
-	return event->pmu->stop(event);
-}
-
-static int perf_event_start(struct perf_event *event)
-{
-	if (!event->pmu->start)
-		return event->pmu->enable(event);
-
-	return event->pmu->start(event);
-}
-
-static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	s64 period, sample_period;
-	s64 delta;
-
-	period = perf_calculate_period(event, nsec, count);
-
-	delta = (s64)(period - hwc->sample_period);
-	delta = (delta + 7) / 8; /* low pass filter */
-
-	sample_period = hwc->sample_period + delta;
-
-	if (!sample_period)
-		sample_period = 1;
-
-	hwc->sample_period = sample_period;
-
-	if (local64_read(&hwc->period_left) > 8*sample_period) {
-		perf_disable();
-		perf_event_stop(event);
-		local64_set(&hwc->period_left, 0);
-		perf_event_start(event);
-		perf_enable();
-	}
-}
-
-static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
-{
-	struct perf_event *event;
-	struct hw_perf_event *hwc;
-	u64 interrupts, now;
-	s64 delta;
-
-	raw_spin_lock(&ctx->lock);
-	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
-		if (event->state != PERF_EVENT_STATE_ACTIVE)
-			continue;
-
-		if (event->cpu != -1 && event->cpu != smp_processor_id())
-			continue;
-
-		hwc = &event->hw;
-
-		interrupts = hwc->interrupts;
-		hwc->interrupts = 0;
-
-		/*
-		 * unthrottle events on the tick
-		 */
-		if (interrupts == MAX_INTERRUPTS) {
-			perf_log_throttle(event, 1);
-			perf_disable();
-			event->pmu->unthrottle(event);
-			perf_enable();
-		}
-
-		if (!event->attr.freq || !event->attr.sample_freq)
-			continue;
-
-		perf_disable();
-		event->pmu->read(event);
-		now = local64_read(&event->count);
-		delta = now - hwc->freq_count_stamp;
-		hwc->freq_count_stamp = now;
-
-		if (delta > 0)
-			perf_adjust_period(event, TICK_NSEC, delta);
-		perf_enable();
-	}
-	raw_spin_unlock(&ctx->lock);
-}
-
-/*
- * Round-robin a context's events:
- */
-static void rotate_ctx(struct perf_event_context *ctx)
-{
-	raw_spin_lock(&ctx->lock);
-
-	/* Rotate the first entry last of non-pinned groups */
-	list_rotate_left(&ctx->flexible_groups);
-
-	raw_spin_unlock(&ctx->lock);
-}
-
-void perf_event_task_tick(struct task_struct *curr)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx;
-	int rotate = 0;
-
-	if (!atomic_read(&nr_events))
-		return;
-
-	cpuctx = &__get_cpu_var(perf_cpu_context);
-	if (cpuctx->ctx.nr_events &&
-	    cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
-		rotate = 1;
-
-	ctx = curr->perf_event_ctxp;
-	if (ctx && ctx->nr_events && ctx->nr_events != ctx->nr_active)
-		rotate = 1;
-
-	perf_ctx_adjust_freq(&cpuctx->ctx);
-	if (ctx)
-		perf_ctx_adjust_freq(ctx);
-
-	if (!rotate)
-		return;
-
-	perf_disable();
-	cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
-	if (ctx)
-		task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
-
-	rotate_ctx(&cpuctx->ctx);
-	if (ctx)
-		rotate_ctx(ctx);
-
-	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
-	if (ctx)
-		task_ctx_sched_in(curr, EVENT_FLEXIBLE);
-	perf_enable();
-}
-
-static int event_enable_on_exec(struct perf_event *event,
-				struct perf_event_context *ctx)
-{
-	if (!event->attr.enable_on_exec)
-		return 0;
-
-	event->attr.enable_on_exec = 0;
-	if (event->state >= PERF_EVENT_STATE_INACTIVE)
-		return 0;
-
-	__perf_event_mark_enabled(event, ctx);
-
-	return 1;
-}
-
-/*
- * Enable all of a task's events that have been marked enable-on-exec.
- * This expects task == current.
- */
-static void perf_event_enable_on_exec(struct task_struct *task)
-{
-	struct perf_event_context *ctx;
-	struct perf_event *event;
-	unsigned long flags;
-	int enabled = 0;
-	int ret;
-
-	local_irq_save(flags);
-	ctx = task->perf_event_ctxp;
-	if (!ctx || !ctx->nr_events)
-		goto out;
-
-	__perf_event_task_sched_out(ctx);
-
-	raw_spin_lock(&ctx->lock);
-
-	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
-		ret = event_enable_on_exec(event, ctx);
-		if (ret)
-			enabled = 1;
-	}
-
-	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
-		ret = event_enable_on_exec(event, ctx);
-		if (ret)
-			enabled = 1;
-	}
-
-	/*
-	 * Unclone this context if we enabled any event.
-	 */
-	if (enabled)
-		unclone_ctx(ctx);
-
-	raw_spin_unlock(&ctx->lock);
-
-	perf_event_task_sched_in(task);
- out:
-	local_irq_restore(flags);
-}
-
-/*
- * Cross CPU call to read the hardware event
- */
-static void __perf_event_read(void *info)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
-
-	/*
-	 * If this is a task context, we need to check whether it is
-	 * the current task context of this cpu.  If not it has been
-	 * scheduled out before the smp call arrived.  In that case
-	 * event->count would have been updated to a recent sample
-	 * when the event was scheduled out.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx)
-		return;
-
-	raw_spin_lock(&ctx->lock);
-	update_context_time(ctx);
-	update_event_times(event);
-	raw_spin_unlock(&ctx->lock);
-
-	event->pmu->read(event);
-}
-
-static inline u64 perf_event_count(struct perf_event *event)
-{
-	return local64_read(&event->count) + atomic64_read(&event->child_count);
-}
-
-static u64 perf_event_read(struct perf_event *event)
-{
-	/*
-	 * If event is enabled and currently active on a CPU, update the
-	 * value in the event structure:
-	 */
-	if (event->state == PERF_EVENT_STATE_ACTIVE) {
-		smp_call_function_single(event->oncpu,
-					 __perf_event_read, event, 1);
-	} else if (event->state == PERF_EVENT_STATE_INACTIVE) {
-		struct perf_event_context *ctx = event->ctx;
-		unsigned long flags;
-
-		raw_spin_lock_irqsave(&ctx->lock, flags);
-		update_context_time(ctx);
-		update_event_times(event);
-		raw_spin_unlock_irqrestore(&ctx->lock, flags);
-	}
-
-	return perf_event_count(event);
-}
-
-/*
- * Initialize the perf_event context in a task_struct:
- */
-static void
-__perf_event_init_context(struct perf_event_context *ctx,
-			    struct task_struct *task)
-{
-	raw_spin_lock_init(&ctx->lock);
-	mutex_init(&ctx->mutex);
-	INIT_LIST_HEAD(&ctx->pinned_groups);
-	INIT_LIST_HEAD(&ctx->flexible_groups);
-	INIT_LIST_HEAD(&ctx->event_list);
-	atomic_set(&ctx->refcount, 1);
-	ctx->task = task;
-}
-
-static struct perf_event_context *find_get_context(pid_t pid, int cpu)
-{
-	struct perf_event_context *ctx;
-	struct perf_cpu_context *cpuctx;
-	struct task_struct *task;
-	unsigned long flags;
-	int err;
-
-	if (pid == -1 && cpu != -1) {
-		/* Must be root to operate on a CPU event: */
-		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
-			return ERR_PTR(-EACCES);
-
-		if (cpu < 0 || cpu >= nr_cpumask_bits)
-			return ERR_PTR(-EINVAL);
-
-		/*
-		 * We could be clever and allow to attach a event to an
-		 * offline CPU and activate it when the CPU comes up, but
-		 * that's for later.
-		 */
-		if (!cpu_online(cpu))
-			return ERR_PTR(-ENODEV);
-
-		cpuctx = &per_cpu(perf_cpu_context, cpu);
-		ctx = &cpuctx->ctx;
-		get_ctx(ctx);
-
-		return ctx;
-	}
-
-	rcu_read_lock();
-	if (!pid)
-		task = current;
-	else
-		task = find_task_by_vpid(pid);
-	if (task)
-		get_task_struct(task);
-	rcu_read_unlock();
-
-	if (!task)
-		return ERR_PTR(-ESRCH);
-
-	/*
-	 * Can't attach events to a dying task.
-	 */
-	err = -ESRCH;
-	if (task->flags & PF_EXITING)
-		goto errout;
-
-	/* Reuse ptrace permission checks for now. */
-	err = -EACCES;
-	if (!ptrace_may_access(task, PTRACE_MODE_READ))
-		goto errout;
-
- retry:
-	ctx = perf_lock_task_context(task, &flags);
-	if (ctx) {
-		unclone_ctx(ctx);
-		raw_spin_unlock_irqrestore(&ctx->lock, flags);
-	}
-
-	if (!ctx) {
-		ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
-		err = -ENOMEM;
-		if (!ctx)
-			goto errout;
-		__perf_event_init_context(ctx, task);
-		get_ctx(ctx);
-		if (cmpxchg(&task->perf_event_ctxp, NULL, ctx)) {
-			/*
-			 * We raced with some other task; use
-			 * the context they set.
-			 */
-			kfree(ctx);
-			goto retry;
-		}
-		get_task_struct(task);
-	}
-
-	put_task_struct(task);
-	return ctx;
-
- errout:
-	put_task_struct(task);
-	return ERR_PTR(err);
-}
-
-static void perf_event_free_filter(struct perf_event *event);
-
-static void free_event_rcu(struct rcu_head *head)
-{
-	struct perf_event *event;
-
-	event = container_of(head, struct perf_event, rcu_head);
-	if (event->ns)
-		put_pid_ns(event->ns);
-	perf_event_free_filter(event);
-	kfree(event);
-}
-
-static void perf_pending_sync(struct perf_event *event);
-static void perf_buffer_put(struct perf_buffer *buffer);
-
-static void free_event(struct perf_event *event)
-{
-	perf_pending_sync(event);
-
-	if (!event->parent) {
-		atomic_dec(&nr_events);
-		if (event->attr.mmap || event->attr.mmap_data)
-			atomic_dec(&nr_mmap_events);
-		if (event->attr.comm)
-			atomic_dec(&nr_comm_events);
-		if (event->attr.task)
-			atomic_dec(&nr_task_events);
-	}
-
-	if (event->buffer) {
-		perf_buffer_put(event->buffer);
-		event->buffer = NULL;
-	}
-
-	if (event->destroy)
-		event->destroy(event);
-
-	put_ctx(event->ctx);
-	call_rcu(&event->rcu_head, free_event_rcu);
-}
-
-int perf_event_release_kernel(struct perf_event *event)
-{
-	struct perf_event_context *ctx = event->ctx;
-
-	/*
-	 * Remove from the PMU, can't get re-enabled since we got
-	 * here because the last ref went.
-	 */
-	perf_event_disable(event);
-
-	WARN_ON_ONCE(ctx->parent_ctx);
-	/*
-	 * There are two ways this annotation is useful:
-	 *
-	 *  1) there is a lock recursion from perf_event_exit_task
-	 *     see the comment there.
-	 *
-	 *  2) there is a lock-inversion with mmap_sem through
-	 *     perf_event_read_group(), which takes faults while
-	 *     holding ctx->mutex, however this is called after
-	 *     the last filedesc died, so there is no possibility
-	 *     to trigger the AB-BA case.
-	 */
-	mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
-	raw_spin_lock_irq(&ctx->lock);
-	perf_group_detach(event);
-	list_del_event(event, ctx);
-	raw_spin_unlock_irq(&ctx->lock);
-	mutex_unlock(&ctx->mutex);
-
-	mutex_lock(&event->owner->perf_event_mutex);
-	list_del_init(&event->owner_entry);
-	mutex_unlock(&event->owner->perf_event_mutex);
-	put_task_struct(event->owner);
-
-	free_event(event);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(perf_event_release_kernel);
-
-/*
- * Called when the last reference to the file is gone.
- */
-static int perf_release(struct inode *inode, struct file *file)
-{
-	struct perf_event *event = file->private_data;
-
-	file->private_data = NULL;
-
-	return perf_event_release_kernel(event);
-}
-
-static int perf_event_read_size(struct perf_event *event)
-{
-	int entry = sizeof(u64); /* value */
-	int size = 0;
-	int nr = 1;
-
-	if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-		size += sizeof(u64);
-
-	if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
-		size += sizeof(u64);
-
-	if (event->attr.read_format & PERF_FORMAT_ID)
-		entry += sizeof(u64);
-
-	if (event->attr.read_format & PERF_FORMAT_GROUP) {
-		nr += event->group_leader->nr_siblings;
-		size += sizeof(u64);
-	}
-
-	size += entry * nr;
-
-	return size;
-}
-
-u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
-{
-	struct perf_event *child;
-	u64 total = 0;
-
-	*enabled = 0;
-	*running = 0;
-
-	mutex_lock(&event->child_mutex);
-	total += perf_event_read(event);
-	*enabled += event->total_time_enabled +
-			atomic64_read(&event->child_total_time_enabled);
-	*running += event->total_time_running +
-			atomic64_read(&event->child_total_time_running);
-
-	list_for_each_entry(child, &event->child_list, child_list) {
-		total += perf_event_read(child);
-		*enabled += child->total_time_enabled;
-		*running += child->total_time_running;
-	}
-	mutex_unlock(&event->child_mutex);
-
-	return total;
-}
-EXPORT_SYMBOL_GPL(perf_event_read_value);
-
-static int perf_event_read_group(struct perf_event *event,
-				   u64 read_format, char __user *buf)
-{
-	struct perf_event *leader = event->group_leader, *sub;
-	int n = 0, size = 0, ret = -EFAULT;
-	struct perf_event_context *ctx = leader->ctx;
-	u64 values[5];
-	u64 count, enabled, running;
-
-	mutex_lock(&ctx->mutex);
-	count = perf_event_read_value(leader, &enabled, &running);
-
-	values[n++] = 1 + leader->nr_siblings;
-	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-		values[n++] = enabled;
-	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
-		values[n++] = running;
-	values[n++] = count;
-	if (read_format & PERF_FORMAT_ID)
-		values[n++] = primary_event_id(leader);
-
-	size = n * sizeof(u64);
-
-	if (copy_to_user(buf, values, size))
-		goto unlock;
-
-	ret = size;
-
-	list_for_each_entry(sub, &leader->sibling_list, group_entry) {
-		n = 0;
-
-		values[n++] = perf_event_read_value(sub, &enabled, &running);
-		if (read_format & PERF_FORMAT_ID)
-			values[n++] = primary_event_id(sub);
-
-		size = n * sizeof(u64);
-
-		if (copy_to_user(buf + ret, values, size)) {
-			ret = -EFAULT;
-			goto unlock;
-		}
-
-		ret += size;
-	}
-unlock:
-	mutex_unlock(&ctx->mutex);
-
-	return ret;
-}
-
-static int perf_event_read_one(struct perf_event *event,
-				 u64 read_format, char __user *buf)
-{
-	u64 enabled, running;
-	u64 values[4];
-	int n = 0;
-
-	values[n++] = perf_event_read_value(event, &enabled, &running);
-	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-		values[n++] = enabled;
-	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
-		values[n++] = running;
-	if (read_format & PERF_FORMAT_ID)
-		values[n++] = primary_event_id(event);
-
-	if (copy_to_user(buf, values, n * sizeof(u64)))
-		return -EFAULT;
-
-	return n * sizeof(u64);
-}
-
-/*
- * Read the performance event - simple non blocking version for now
- */
-static ssize_t
-perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
-{
-	u64 read_format = event->attr.read_format;
-	int ret;
-
-	/*
-	 * Return end-of-file for a read on a event that is in
-	 * error state (i.e. because it was pinned but it couldn't be
-	 * scheduled on to the CPU at some point).
-	 */
-	if (event->state == PERF_EVENT_STATE_ERROR)
-		return 0;
-
-	if (count < perf_event_read_size(event))
-		return -ENOSPC;
-
-	WARN_ON_ONCE(event->ctx->parent_ctx);
-	if (read_format & PERF_FORMAT_GROUP)
-		ret = perf_event_read_group(event, read_format, buf);
-	else
-		ret = perf_event_read_one(event, read_format, buf);
-
-	return ret;
-}
-
-static ssize_t
-perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
-{
-	struct perf_event *event = file->private_data;
-
-	return perf_read_hw(event, buf, count);
-}
-
-static unsigned int perf_poll(struct file *file, poll_table *wait)
-{
-	struct perf_event *event = file->private_data;
-	struct perf_buffer *buffer;
-	unsigned int events = POLL_HUP;
-
-	rcu_read_lock();
-	buffer = rcu_dereference(event->buffer);
-	if (buffer)
-		events = atomic_xchg(&buffer->poll, 0);
-	rcu_read_unlock();
-
-	poll_wait(file, &event->waitq, wait);
-
-	return events;
-}
-
-static void perf_event_reset(struct perf_event *event)
-{
-	(void)perf_event_read(event);
-	local64_set(&event->count, 0);
-	perf_event_update_userpage(event);
-}
-
-/*
- * Holding the top-level event's child_mutex means that any
- * descendant process that has inherited this event will block
- * in sync_child_event if it goes to exit, thus satisfying the
- * task existence requirements of perf_event_enable/disable.
- */
-static void perf_event_for_each_child(struct perf_event *event,
-					void (*func)(struct perf_event *))
-{
-	struct perf_event *child;
-
-	WARN_ON_ONCE(event->ctx->parent_ctx);
-	mutex_lock(&event->child_mutex);
-	func(event);
-	list_for_each_entry(child, &event->child_list, child_list)
-		func(child);
-	mutex_unlock(&event->child_mutex);
-}
-
-static void perf_event_for_each(struct perf_event *event,
-				  void (*func)(struct perf_event *))
-{
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_event *sibling;
-
-	WARN_ON_ONCE(ctx->parent_ctx);
-	mutex_lock(&ctx->mutex);
-	event = event->group_leader;
-
-	perf_event_for_each_child(event, func);
-	func(event);
-	list_for_each_entry(sibling, &event->sibling_list, group_entry)
-		perf_event_for_each_child(event, func);
-	mutex_unlock(&ctx->mutex);
-}
-
-static int perf_event_period(struct perf_event *event, u64 __user *arg)
-{
-	struct perf_event_context *ctx = event->ctx;
-	int ret = 0;
-	u64 value;
-
-	if (!event->attr.sample_period)
-		return -EINVAL;
-
-	if (copy_from_user(&value, arg, sizeof(value)))
-		return -EFAULT;
-
-	if (!value)
-		return -EINVAL;
-
-	raw_spin_lock_irq(&ctx->lock);
-	if (event->attr.freq) {
-		if (value > sysctl_perf_event_sample_rate) {
-			ret = -EINVAL;
-			goto unlock;
-		}
-
-		event->attr.sample_freq = value;
-	} else {
-		event->attr.sample_period = value;
-		event->hw.sample_period = value;
-	}
-unlock:
-	raw_spin_unlock_irq(&ctx->lock);
-
-	return ret;
-}
-
-static const struct file_operations perf_fops;
-
-static struct perf_event *perf_fget_light(int fd, int *fput_needed)
-{
-	struct file *file;
-
-	file = fget_light(fd, fput_needed);
-	if (!file)
-		return ERR_PTR(-EBADF);
-
-	if (file->f_op != &perf_fops) {
-		fput_light(file, *fput_needed);
-		*fput_needed = 0;
-		return ERR_PTR(-EBADF);
-	}
-
-	return file->private_data;
-}
-
-static int perf_event_set_output(struct perf_event *event,
-				 struct perf_event *output_event);
-static int perf_event_set_filter(struct perf_event *event, void __user *arg);
-
-static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
-{
-	struct perf_event *event = file->private_data;
-	void (*func)(struct perf_event *);
-	u32 flags = arg;
-
-	switch (cmd) {
-	case PERF_EVENT_IOC_ENABLE:
-		func = perf_event_enable;
-		break;
-	case PERF_EVENT_IOC_DISABLE:
-		func = perf_event_disable;
-		break;
-	case PERF_EVENT_IOC_RESET:
-		func = perf_event_reset;
-		break;
-
-	case PERF_EVENT_IOC_REFRESH:
-		return perf_event_refresh(event, arg);
-
-	case PERF_EVENT_IOC_PERIOD:
-		return perf_event_period(event, (u64 __user *)arg);
-
-	case PERF_EVENT_IOC_SET_OUTPUT:
-	{
-		struct perf_event *output_event = NULL;
-		int fput_needed = 0;
-		int ret;
-
-		if (arg != -1) {
-			output_event = perf_fget_light(arg, &fput_needed);
-			if (IS_ERR(output_event))
-				return PTR_ERR(output_event);
-		}
-
-		ret = perf_event_set_output(event, output_event);
-		if (output_event)
-			fput_light(output_event->filp, fput_needed);
-
-		return ret;
-	}
-
-	case PERF_EVENT_IOC_SET_FILTER:
-		return perf_event_set_filter(event, (void __user *)arg);
-
-	default:
-		return -ENOTTY;
-	}
-
-	if (flags & PERF_IOC_FLAG_GROUP)
-		perf_event_for_each(event, func);
-	else
-		perf_event_for_each_child(event, func);
-
-	return 0;
-}
-
-int perf_event_task_enable(void)
-{
-	struct perf_event *event;
-
-	mutex_lock(&current->perf_event_mutex);
-	list_for_each_entry(event, &current->perf_event_list, owner_entry)
-		perf_event_for_each_child(event, perf_event_enable);
-	mutex_unlock(&current->perf_event_mutex);
-
-	return 0;
-}
-
-int perf_event_task_disable(void)
-{
-	struct perf_event *event;
-
-	mutex_lock(&current->perf_event_mutex);
-	list_for_each_entry(event, &current->perf_event_list, owner_entry)
-		perf_event_for_each_child(event, perf_event_disable);
-	mutex_unlock(&current->perf_event_mutex);
-
-	return 0;
-}
-
-#ifndef PERF_EVENT_INDEX_OFFSET
-# define PERF_EVENT_INDEX_OFFSET 0
-#endif
-
-static int perf_event_index(struct perf_event *event)
-{
-	if (event->state != PERF_EVENT_STATE_ACTIVE)
-		return 0;
-
-	return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
-}
-
-/*
- * Callers need to ensure there can be no nesting of this function, otherwise
- * the seqlock logic goes bad. We can not serialize this because the arch
- * code calls this from NMI context.
- */
-void perf_event_update_userpage(struct perf_event *event)
-{
-	struct perf_event_mmap_page *userpg;
-	struct perf_buffer *buffer;
-
-	rcu_read_lock();
-	buffer = rcu_dereference(event->buffer);
-	if (!buffer)
-		goto unlock;
-
-	userpg = buffer->user_page;
-
-	/*
-	 * Disable preemption so as to not let the corresponding user-space
-	 * spin too long if we get preempted.
-	 */
-	preempt_disable();
-	++userpg->lock;
-	barrier();
-	userpg->index = perf_event_index(event);
-	userpg->offset = perf_event_count(event);
-	if (event->state == PERF_EVENT_STATE_ACTIVE)
-		userpg->offset -= local64_read(&event->hw.prev_count);
-
-	userpg->time_enabled = event->total_time_enabled +
-			atomic64_read(&event->child_total_time_enabled);
-
-	userpg->time_running = event->total_time_running +
-			atomic64_read(&event->child_total_time_running);
-
-	barrier();
-	++userpg->lock;
-	preempt_enable();
-unlock:
-	rcu_read_unlock();
-}
-
-static unsigned long perf_data_size(struct perf_buffer *buffer);
-
-static void
-perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
-{
-	long max_size = perf_data_size(buffer);
-
-	if (watermark)
-		buffer->watermark = min(max_size, watermark);
-
-	if (!buffer->watermark)
-		buffer->watermark = max_size / 2;
-
-	if (flags & PERF_BUFFER_WRITABLE)
-		buffer->writable = 1;
-
-	atomic_set(&buffer->refcount, 1);
-}
-
-#ifndef CONFIG_PERF_USE_VMALLOC
-
-/*
- * Back perf_mmap() with regular GFP_KERNEL-0 pages.
- */
-
-static struct page *
-perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
-{
-	if (pgoff > buffer->nr_pages)
-		return NULL;
-
-	if (pgoff == 0)
-		return virt_to_page(buffer->user_page);
-
-	return virt_to_page(buffer->data_pages[pgoff - 1]);
-}
-
-static void *perf_mmap_alloc_page(int cpu)
-{
-	struct page *page;
-	int node;
-
-	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
-	page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
-	if (!page)
-		return NULL;
-
-	return page_address(page);
-}
-
-static struct perf_buffer *
-perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
-{
-	struct perf_buffer *buffer;
-	unsigned long size;
-	int i;
-
-	size = sizeof(struct perf_buffer);
-	size += nr_pages * sizeof(void *);
-
-	buffer = kzalloc(size, GFP_KERNEL);
-	if (!buffer)
-		goto fail;
-
-	buffer->user_page = perf_mmap_alloc_page(cpu);
-	if (!buffer->user_page)
-		goto fail_user_page;
-
-	for (i = 0; i < nr_pages; i++) {
-		buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
-		if (!buffer->data_pages[i])
-			goto fail_data_pages;
-	}
-
-	buffer->nr_pages = nr_pages;
-
-	perf_buffer_init(buffer, watermark, flags);
-
-	return buffer;
-
-fail_data_pages:
-	for (i--; i >= 0; i--)
-		free_page((unsigned long)buffer->data_pages[i]);
-
-	free_page((unsigned long)buffer->user_page);
-
-fail_user_page:
-	kfree(buffer);
-
-fail:
-	return NULL;
-}
-
-static void perf_mmap_free_page(unsigned long addr)
-{
-	struct page *page = virt_to_page((void *)addr);
-
-	page->mapping = NULL;
-	__free_page(page);
-}
-
-static void perf_buffer_free(struct perf_buffer *buffer)
-{
-	int i;
-
-	perf_mmap_free_page((unsigned long)buffer->user_page);
-	for (i = 0; i < buffer->nr_pages; i++)
-		perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
-	kfree(buffer);
-}
-
-static inline int page_order(struct perf_buffer *buffer)
-{
-	return 0;
-}
-
-#else
-
-/*
- * Back perf_mmap() with vmalloc memory.
- *
- * Required for architectures that have d-cache aliasing issues.
- */
-
-static inline int page_order(struct perf_buffer *buffer)
-{
-	return buffer->page_order;
-}
-
-static struct page *
-perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
-{
-	if (pgoff > (1UL << page_order(buffer)))
-		return NULL;
-
-	return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
-}
-
-static void perf_mmap_unmark_page(void *addr)
-{
-	struct page *page = vmalloc_to_page(addr);
-
-	page->mapping = NULL;
-}
-
-static void perf_buffer_free_work(struct work_struct *work)
-{
-	struct perf_buffer *buffer;
-	void *base;
-	int i, nr;
-
-	buffer = container_of(work, struct perf_buffer, work);
-	nr = 1 << page_order(buffer);
-
-	base = buffer->user_page;
-	for (i = 0; i < nr + 1; i++)
-		perf_mmap_unmark_page(base + (i * PAGE_SIZE));
-
-	vfree(base);
-	kfree(buffer);
-}
-
-static void perf_buffer_free(struct perf_buffer *buffer)
-{
-	schedule_work(&buffer->work);
-}
-
-static struct perf_buffer *
-perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
-{
-	struct perf_buffer *buffer;
-	unsigned long size;
-	void *all_buf;
-
-	size = sizeof(struct perf_buffer);
-	size += sizeof(void *);
-
-	buffer = kzalloc(size, GFP_KERNEL);
-	if (!buffer)
-		goto fail;
-
-	INIT_WORK(&buffer->work, perf_buffer_free_work);
-
-	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
-	if (!all_buf)
-		goto fail_all_buf;
-
-	buffer->user_page = all_buf;
-	buffer->data_pages[0] = all_buf + PAGE_SIZE;
-	buffer->page_order = ilog2(nr_pages);
-	buffer->nr_pages = 1;
-
-	perf_buffer_init(buffer, watermark, flags);
-
-	return buffer;
-
-fail_all_buf:
-	kfree(buffer);
-
-fail:
-	return NULL;
-}
-
-#endif
-
-static unsigned long perf_data_size(struct perf_buffer *buffer)
-{
-	return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
-}
-
-static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
-{
-	struct perf_event *event = vma->vm_file->private_data;
-	struct perf_buffer *buffer;
-	int ret = VM_FAULT_SIGBUS;
-
-	if (vmf->flags & FAULT_FLAG_MKWRITE) {
-		if (vmf->pgoff == 0)
-			ret = 0;
-		return ret;
-	}
-
-	rcu_read_lock();
-	buffer = rcu_dereference(event->buffer);
-	if (!buffer)
-		goto unlock;
-
-	if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
-		goto unlock;
-
-	vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
-	if (!vmf->page)
-		goto unlock;
-
-	get_page(vmf->page);
-	vmf->page->mapping = vma->vm_file->f_mapping;
-	vmf->page->index   = vmf->pgoff;
-
-	ret = 0;
-unlock:
-	rcu_read_unlock();
-
-	return ret;
-}
-
-static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
-{
-	struct perf_buffer *buffer;
-
-	buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
-	perf_buffer_free(buffer);
-}
-
-static struct perf_buffer *perf_buffer_get(struct perf_event *event)
-{
-	struct perf_buffer *buffer;
-
-	rcu_read_lock();
-	buffer = rcu_dereference(event->buffer);
-	if (buffer) {
-		if (!atomic_inc_not_zero(&buffer->refcount))
-			buffer = NULL;
-	}
-	rcu_read_unlock();
-
-	return buffer;
-}
-
-static void perf_buffer_put(struct perf_buffer *buffer)
-{
-	if (!atomic_dec_and_test(&buffer->refcount))
-		return;
-
-	call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
-}
-
-static void perf_mmap_open(struct vm_area_struct *vma)
-{
-	struct perf_event *event = vma->vm_file->private_data;
-
-	atomic_inc(&event->mmap_count);
-}
-
-static void perf_mmap_close(struct vm_area_struct *vma)
-{
-	struct perf_event *event = vma->vm_file->private_data;
-
-	if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
-		unsigned long size = perf_data_size(event->buffer);
-		struct user_struct *user = event->mmap_user;
-		struct perf_buffer *buffer = event->buffer;
-
-		atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
-		vma->vm_mm->locked_vm -= event->mmap_locked;
-		rcu_assign_pointer(event->buffer, NULL);
-		mutex_unlock(&event->mmap_mutex);
-
-		perf_buffer_put(buffer);
-		free_uid(user);
-	}
-}
-
-static const struct vm_operations_struct perf_mmap_vmops = {
-	.open		= perf_mmap_open,
-	.close		= perf_mmap_close,
-	.fault		= perf_mmap_fault,
-	.page_mkwrite	= perf_mmap_fault,
-};
-
-static int perf_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	struct perf_event *event = file->private_data;
-	unsigned long user_locked, user_lock_limit;
-	struct user_struct *user = current_user();
-	unsigned long locked, lock_limit;
-	struct perf_buffer *buffer;
-	unsigned long vma_size;
-	unsigned long nr_pages;
-	long user_extra, extra;
-	int ret = 0, flags = 0;
-
-	/*
-	 * Don't allow mmap() of inherited per-task counters. This would
-	 * create a performance issue due to all children writing to the
-	 * same buffer.
-	 */
-	if (event->cpu == -1 && event->attr.inherit)
-		return -EINVAL;
-
-	if (!(vma->vm_flags & VM_SHARED))
-		return -EINVAL;
-
-	vma_size = vma->vm_end - vma->vm_start;
-	nr_pages = (vma_size / PAGE_SIZE) - 1;
-
-	/*
-	 * If we have buffer pages ensure they're a power-of-two number, so we
-	 * can do bitmasks instead of modulo.
-	 */
-	if (nr_pages != 0 && !is_power_of_2(nr_pages))
-		return -EINVAL;
-
-	if (vma_size != PAGE_SIZE * (1 + nr_pages))
-		return -EINVAL;
-
-	if (vma->vm_pgoff != 0)
-		return -EINVAL;
-
-	WARN_ON_ONCE(event->ctx->parent_ctx);
-	mutex_lock(&event->mmap_mutex);
-	if (event->buffer) {
-		if (event->buffer->nr_pages == nr_pages)
-			atomic_inc(&event->buffer->refcount);
-		else
-			ret = -EINVAL;
-		goto unlock;
-	}
-
-	user_extra = nr_pages + 1;
-	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
-
-	/*
-	 * Increase the limit linearly with more CPUs:
-	 */
-	user_lock_limit *= num_online_cpus();
-
-	user_locked = atomic_long_read(&user->locked_vm) + user_extra;
-
-	extra = 0;
-	if (user_locked > user_lock_limit)
-		extra = user_locked - user_lock_limit;
-
-	lock_limit = rlimit(RLIMIT_MEMLOCK);
-	lock_limit >>= PAGE_SHIFT;
-	locked = vma->vm_mm->locked_vm + extra;
-
-	if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
-		!capable(CAP_IPC_LOCK)) {
-		ret = -EPERM;
-		goto unlock;
-	}
-
-	WARN_ON(event->buffer);
-
-	if (vma->vm_flags & VM_WRITE)
-		flags |= PERF_BUFFER_WRITABLE;
-
-	buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
-				   event->cpu, flags);
-	if (!buffer) {
-		ret = -ENOMEM;
-		goto unlock;
-	}
-	rcu_assign_pointer(event->buffer, buffer);
-
-	atomic_long_add(user_extra, &user->locked_vm);
-	event->mmap_locked = extra;
-	event->mmap_user = get_current_user();
-	vma->vm_mm->locked_vm += event->mmap_locked;
-
-unlock:
-	if (!ret)
-		atomic_inc(&event->mmap_count);
-	mutex_unlock(&event->mmap_mutex);
-
-	vma->vm_flags |= VM_RESERVED;
-	vma->vm_ops = &perf_mmap_vmops;
-
-	return ret;
-}
-
-static int perf_fasync(int fd, struct file *filp, int on)
-{
-	struct inode *inode = filp->f_path.dentry->d_inode;
-	struct perf_event *event = filp->private_data;
-	int retval;
-
-	mutex_lock(&inode->i_mutex);
-	retval = fasync_helper(fd, filp, on, &event->fasync);
-	mutex_unlock(&inode->i_mutex);
-
-	if (retval < 0)
-		return retval;
-
-	return 0;
-}
-
-static const struct file_operations perf_fops = {
-	.llseek			= no_llseek,
-	.release		= perf_release,
-	.read			= perf_read,
-	.poll			= perf_poll,
-	.unlocked_ioctl		= perf_ioctl,
-	.compat_ioctl		= perf_ioctl,
-	.mmap			= perf_mmap,
-	.fasync			= perf_fasync,
-};
-
-/*
- * Perf event wakeup
- *
- * If there's data, ensure we set the poll() state and publish everything
- * to user-space before waking everybody up.
- */
-
-void perf_event_wakeup(struct perf_event *event)
-{
-	wake_up_all(&event->waitq);
-
-	if (event->pending_kill) {
-		kill_fasync(&event->fasync, SIGIO, event->pending_kill);
-		event->pending_kill = 0;
-	}
-}
-
-/*
- * Pending wakeups
- *
- * Handle the case where we need to wakeup up from NMI (or rq->lock) context.
- *
- * The NMI bit means we cannot possibly take locks. Therefore, maintain a
- * single linked list and use cmpxchg() to add entries lockless.
- */
-
-static void perf_pending_event(struct perf_pending_entry *entry)
-{
-	struct perf_event *event = container_of(entry,
-			struct perf_event, pending);
-
-	if (event->pending_disable) {
-		event->pending_disable = 0;
-		__perf_event_disable(event);
-	}
-
-	if (event->pending_wakeup) {
-		event->pending_wakeup = 0;
-		perf_event_wakeup(event);
-	}
-}
-
-#define PENDING_TAIL ((struct perf_pending_entry *)-1UL)
-
-static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
-	PENDING_TAIL,
-};
-
-static void perf_pending_queue(struct perf_pending_entry *entry,
-			       void (*func)(struct perf_pending_entry *))
-{
-	struct perf_pending_entry **head;
-
-	if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL)
-		return;
-
-	entry->func = func;
-
-	head = &get_cpu_var(perf_pending_head);
-
-	do {
-		entry->next = *head;
-	} while (cmpxchg(head, entry->next, entry) != entry->next);
-
-	set_perf_event_pending();
-
-	put_cpu_var(perf_pending_head);
-}
-
-static int __perf_pending_run(void)
-{
-	struct perf_pending_entry *list;
-	int nr = 0;
-
-	list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL);
-	while (list != PENDING_TAIL) {
-		void (*func)(struct perf_pending_entry *);
-		struct perf_pending_entry *entry = list;
-
-		list = list->next;
-
-		func = entry->func;
-		entry->next = NULL;
-		/*
-		 * Ensure we observe the unqueue before we issue the wakeup,
-		 * so that we won't be waiting forever.
-		 * -- see perf_not_pending().
-		 */
-		smp_wmb();
-
-		func(entry);
-		nr++;
-	}
-
-	return nr;
-}
-
-static inline int perf_not_pending(struct perf_event *event)
-{
-	/*
-	 * If we flush on whatever cpu we run, there is a chance we don't
-	 * need to wait.
-	 */
-	get_cpu();
-	__perf_pending_run();
-	put_cpu();
-
-	/*
-	 * Ensure we see the proper queue state before going to sleep
-	 * so that we do not miss the wakeup. -- see perf_pending_handle()
-	 */
-	smp_rmb();
-	return event->pending.next == NULL;
-}
-
-static void perf_pending_sync(struct perf_event *event)
-{
-	wait_event(event->waitq, perf_not_pending(event));
-}
-
-void perf_event_do_pending(void)
-{
-	__perf_pending_run();
-}
-
-/*
- * Callchain support -- arch specific
- */
-
-__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
-{
-	return NULL;
-}
-
-
-/*
- * We assume there is only KVM supporting the callbacks.
- * Later on, we might change it to a list if there is
- * another virtualization implementation supporting the callbacks.
- */
-struct perf_guest_info_callbacks *perf_guest_cbs;
-
-int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
-{
-	perf_guest_cbs = cbs;
-	return 0;
-}
-EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
-
-int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
-{
-	perf_guest_cbs = NULL;
-	return 0;
-}
-EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
-
-/*
- * Output
- */
-static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
-			      unsigned long offset, unsigned long head)
-{
-	unsigned long mask;
-
-	if (!buffer->writable)
-		return true;
-
-	mask = perf_data_size(buffer) - 1;
-
-	offset = (offset - tail) & mask;
-	head   = (head   - tail) & mask;
-
-	if ((int)(head - offset) < 0)
-		return false;
-
-	return true;
-}
-
-static void perf_output_wakeup(struct perf_output_handle *handle)
-{
-	atomic_set(&handle->buffer->poll, POLL_IN);
-
-	if (handle->nmi) {
-		handle->event->pending_wakeup = 1;
-		perf_pending_queue(&handle->event->pending,
-				   perf_pending_event);
-	} else
-		perf_event_wakeup(handle->event);
-}
-
-/*
- * We need to ensure a later event_id doesn't publish a head when a former
- * event isn't done writing. However since we need to deal with NMIs we
- * cannot fully serialize things.
- *
- * We only publish the head (and generate a wakeup) when the outer-most
- * event completes.
- */
-static void perf_output_get_handle(struct perf_output_handle *handle)
-{
-	struct perf_buffer *buffer = handle->buffer;
-
-	preempt_disable();
-	local_inc(&buffer->nest);
-	handle->wakeup = local_read(&buffer->wakeup);
-}
-
-static void perf_output_put_handle(struct perf_output_handle *handle)
-{
-	struct perf_buffer *buffer = handle->buffer;
-	unsigned long head;
-
-again:
-	head = local_read(&buffer->head);
-
-	/*
-	 * IRQ/NMI can happen here, which means we can miss a head update.
-	 */
-
-	if (!local_dec_and_test(&buffer->nest))
-		goto out;
-
-	/*
-	 * Publish the known good head. Rely on the full barrier implied
-	 * by atomic_dec_and_test() order the buffer->head read and this
-	 * write.
-	 */
-	buffer->user_page->data_head = head;
-
-	/*
-	 * Now check if we missed an update, rely on the (compiler)
-	 * barrier in atomic_dec_and_test() to re-read buffer->head.
-	 */
-	if (unlikely(head != local_read(&buffer->head))) {
-		local_inc(&buffer->nest);
-		goto again;
-	}
-
-	if (handle->wakeup != local_read(&buffer->wakeup))
-		perf_output_wakeup(handle);
-
- out:
-	preempt_enable();
-}
-
-__always_inline void perf_output_copy(struct perf_output_handle *handle,
-		      const void *buf, unsigned int len)
-{
-	do {
-		unsigned long size = min_t(unsigned long, handle->size, len);
-
-		memcpy(handle->addr, buf, size);
-
-		len -= size;
-		handle->addr += size;
-		buf += size;
-		handle->size -= size;
-		if (!handle->size) {
-			struct perf_buffer *buffer = handle->buffer;
-
-			handle->page++;
-			handle->page &= buffer->nr_pages - 1;
-			handle->addr = buffer->data_pages[handle->page];
-			handle->size = PAGE_SIZE << page_order(buffer);
-		}
-	} while (len);
-}
-
-int perf_output_begin(struct perf_output_handle *handle,
-		      struct perf_event *event, unsigned int size,
-		      int nmi, int sample)
-{
-	struct perf_buffer *buffer;
-	unsigned long tail, offset, head;
-	int have_lost;
-	struct {
-		struct perf_event_header header;
-		u64			 id;
-		u64			 lost;
-	} lost_event;
-
-	rcu_read_lock();
-	/*
-	 * For inherited events we send all the output towards the parent.
-	 */
-	if (event->parent)
-		event = event->parent;
-
-	buffer = rcu_dereference(event->buffer);
-	if (!buffer)
-		goto out;
-
-	handle->buffer	= buffer;
-	handle->event	= event;
-	handle->nmi	= nmi;
-	handle->sample	= sample;
-
-	if (!buffer->nr_pages)
-		goto out;
-
-	have_lost = local_read(&buffer->lost);
-	if (have_lost)
-		size += sizeof(lost_event);
-
-	perf_output_get_handle(handle);
-
-	do {
-		/*
-		 * Userspace could choose to issue a mb() before updating the
-		 * tail pointer. So that all reads will be completed before the
-		 * write is issued.
-		 */
-		tail = ACCESS_ONCE(buffer->user_page->data_tail);
-		smp_rmb();
-		offset = head = local_read(&buffer->head);
-		head += size;
-		if (unlikely(!perf_output_space(buffer, tail, offset, head)))
-			goto fail;
-	} while (local_cmpxchg(&buffer->head, offset, head) != offset);
-
-	if (head - local_read(&buffer->wakeup) > buffer->watermark)
-		local_add(buffer->watermark, &buffer->wakeup);
-
-	handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
-	handle->page &= buffer->nr_pages - 1;
-	handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
-	handle->addr = buffer->data_pages[handle->page];
-	handle->addr += handle->size;
-	handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
-
-	if (have_lost) {
-		lost_event.header.type = PERF_RECORD_LOST;
-		lost_event.header.misc = 0;
-		lost_event.header.size = sizeof(lost_event);
-		lost_event.id          = event->id;
-		lost_event.lost        = local_xchg(&buffer->lost, 0);
-
-		perf_output_put(handle, lost_event);
-	}
-
-	return 0;
-
-fail:
-	local_inc(&buffer->lost);
-	perf_output_put_handle(handle);
-out:
-	rcu_read_unlock();
-
-	return -ENOSPC;
-}
-
-void perf_output_end(struct perf_output_handle *handle)
-{
-	struct perf_event *event = handle->event;
-	struct perf_buffer *buffer = handle->buffer;
-
-	int wakeup_events = event->attr.wakeup_events;
-
-	if (handle->sample && wakeup_events) {
-		int events = local_inc_return(&buffer->events);
-		if (events >= wakeup_events) {
-			local_sub(wakeup_events, &buffer->events);
-			local_inc(&buffer->wakeup);
-		}
-	}
-
-	perf_output_put_handle(handle);
-	rcu_read_unlock();
-}
-
-static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
-{
-	/*
-	 * only top level events have the pid namespace they were created in
-	 */
-	if (event->parent)
-		event = event->parent;
-
-	return task_tgid_nr_ns(p, event->ns);
-}
-
-static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
-{
-	/*
-	 * only top level events have the pid namespace they were created in
-	 */
-	if (event->parent)
-		event = event->parent;
-
-	return task_pid_nr_ns(p, event->ns);
-}
-
-static void perf_output_read_one(struct perf_output_handle *handle,
-				 struct perf_event *event)
-{
-	u64 read_format = event->attr.read_format;
-	u64 values[4];
-	int n = 0;
-
-	values[n++] = perf_event_count(event);
-	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
-		values[n++] = event->total_time_enabled +
-			atomic64_read(&event->child_total_time_enabled);
-	}
-	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
-		values[n++] = event->total_time_running +
-			atomic64_read(&event->child_total_time_running);
-	}
-	if (read_format & PERF_FORMAT_ID)
-		values[n++] = primary_event_id(event);
-
-	perf_output_copy(handle, values, n * sizeof(u64));
-}
-
-/*
- * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
- */
-static void perf_output_read_group(struct perf_output_handle *handle,
-			    struct perf_event *event)
-{
-	struct perf_event *leader = event->group_leader, *sub;
-	u64 read_format = event->attr.read_format;
-	u64 values[5];
-	int n = 0;
-
-	values[n++] = 1 + leader->nr_siblings;
-
-	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-		values[n++] = leader->total_time_enabled;
-
-	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
-		values[n++] = leader->total_time_running;
-
-	if (leader != event)
-		leader->pmu->read(leader);
-
-	values[n++] = perf_event_count(leader);
-	if (read_format & PERF_FORMAT_ID)
-		values[n++] = primary_event_id(leader);
-
-	perf_output_copy(handle, values, n * sizeof(u64));
-
-	list_for_each_entry(sub, &leader->sibling_list, group_entry) {
-		n = 0;
-
-		if (sub != event)
-			sub->pmu->read(sub);
-
-		values[n++] = perf_event_count(sub);
-		if (read_format & PERF_FORMAT_ID)
-			values[n++] = primary_event_id(sub);
-
-		perf_output_copy(handle, values, n * sizeof(u64));
-	}
-}
-
-static void perf_output_read(struct perf_output_handle *handle,
-			     struct perf_event *event)
-{
-	if (event->attr.read_format & PERF_FORMAT_GROUP)
-		perf_output_read_group(handle, event);
-	else
-		perf_output_read_one(handle, event);
-}
-
-void perf_output_sample(struct perf_output_handle *handle,
-			struct perf_event_header *header,
-			struct perf_sample_data *data,
-			struct perf_event *event)
-{
-	u64 sample_type = data->type;
-
-	perf_output_put(handle, *header);
-
-	if (sample_type & PERF_SAMPLE_IP)
-		perf_output_put(handle, data->ip);
-
-	if (sample_type & PERF_SAMPLE_TID)
-		perf_output_put(handle, data->tid_entry);
-
-	if (sample_type & PERF_SAMPLE_TIME)
-		perf_output_put(handle, data->time);
-
-	if (sample_type & PERF_SAMPLE_ADDR)
-		perf_output_put(handle, data->addr);
-
-	if (sample_type & PERF_SAMPLE_ID)
-		perf_output_put(handle, data->id);
-
-	if (sample_type & PERF_SAMPLE_STREAM_ID)
-		perf_output_put(handle, data->stream_id);
-
-	if (sample_type & PERF_SAMPLE_CPU)
-		perf_output_put(handle, data->cpu_entry);
-
-	if (sample_type & PERF_SAMPLE_PERIOD)
-		perf_output_put(handle, data->period);
-
-	if (sample_type & PERF_SAMPLE_READ)
-		perf_output_read(handle, event);
-
-	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
-		if (data->callchain) {
-			int size = 1;
-
-			if (data->callchain)
-				size += data->callchain->nr;
-
-			size *= sizeof(u64);
-
-			perf_output_copy(handle, data->callchain, size);
-		} else {
-			u64 nr = 0;
-			perf_output_put(handle, nr);
-		}
-	}
-
-	if (sample_type & PERF_SAMPLE_RAW) {
-		if (data->raw) {
-			perf_output_put(handle, data->raw->size);
-			perf_output_copy(handle, data->raw->data,
-					 data->raw->size);
-		} else {
-			struct {
-				u32	size;
-				u32	data;
-			} raw = {
-				.size = sizeof(u32),
-				.data = 0,
-			};
-			perf_output_put(handle, raw);
-		}
-	}
-}
-
-void perf_prepare_sample(struct perf_event_header *header,
-			 struct perf_sample_data *data,
-			 struct perf_event *event,
-			 struct pt_regs *regs)
-{
-	u64 sample_type = event->attr.sample_type;
-
-	data->type = sample_type;
-
-	header->type = PERF_RECORD_SAMPLE;
-	header->size = sizeof(*header);
-
-	header->misc = 0;
-	header->misc |= perf_misc_flags(regs);
-
-	if (sample_type & PERF_SAMPLE_IP) {
-		data->ip = perf_instruction_pointer(regs);
-
-		header->size += sizeof(data->ip);
-	}
-
-	if (sample_type & PERF_SAMPLE_TID) {
-		/* namespace issues */
-		data->tid_entry.pid = perf_event_pid(event, current);
-		data->tid_entry.tid = perf_event_tid(event, current);
-
-		header->size += sizeof(data->tid_entry);
-	}
-
-	if (sample_type & PERF_SAMPLE_TIME) {
-		data->time = perf_clock();
-
-		header->size += sizeof(data->time);
-	}
-
-	if (sample_type & PERF_SAMPLE_ADDR)
-		header->size += sizeof(data->addr);
-
-	if (sample_type & PERF_SAMPLE_ID) {
-		data->id = primary_event_id(event);
-
-		header->size += sizeof(data->id);
-	}
-
-	if (sample_type & PERF_SAMPLE_STREAM_ID) {
-		data->stream_id = event->id;
-
-		header->size += sizeof(data->stream_id);
-	}
-
-	if (sample_type & PERF_SAMPLE_CPU) {
-		data->cpu_entry.cpu		= raw_smp_processor_id();
-		data->cpu_entry.reserved	= 0;
-
-		header->size += sizeof(data->cpu_entry);
-	}
-
-	if (sample_type & PERF_SAMPLE_PERIOD)
-		header->size += sizeof(data->period);
-
-	if (sample_type & PERF_SAMPLE_READ)
-		header->size += perf_event_read_size(event);
-
-	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
-		int size = 1;
-
-		data->callchain = perf_callchain(regs);
-
-		if (data->callchain)
-			size += data->callchain->nr;
-
-		header->size += size * sizeof(u64);
-	}
-
-	if (sample_type & PERF_SAMPLE_RAW) {
-		int size = sizeof(u32);
-
-		if (data->raw)
-			size += data->raw->size;
-		else
-			size += sizeof(u32);
-
-		WARN_ON_ONCE(size & (sizeof(u64)-1));
-		header->size += size;
-	}
-}
-
-static void perf_event_output(struct perf_event *event, int nmi,
-				struct perf_sample_data *data,
-				struct pt_regs *regs)
-{
-	struct perf_output_handle handle;
-	struct perf_event_header header;
-
-	perf_prepare_sample(&header, data, event, regs);
-
-	if (perf_output_begin(&handle, event, header.size, nmi, 1))
-		return;
-
-	perf_output_sample(&handle, &header, data, event);
-
-	perf_output_end(&handle);
-}
-
-/*
- * read event_id
- */
-
-struct perf_read_event {
-	struct perf_event_header	header;
-
-	u32				pid;
-	u32				tid;
-};
-
-static void
-perf_event_read_event(struct perf_event *event,
-			struct task_struct *task)
-{
-	struct perf_output_handle handle;
-	struct perf_read_event read_event = {
-		.header = {
-			.type = PERF_RECORD_READ,
-			.misc = 0,
-			.size = sizeof(read_event) + perf_event_read_size(event),
-		},
-		.pid = perf_event_pid(event, task),
-		.tid = perf_event_tid(event, task),
-	};
-	int ret;
-
-	ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
-	if (ret)
-		return;
-
-	perf_output_put(&handle, read_event);
-	perf_output_read(&handle, event);
-
-	perf_output_end(&handle);
-}
-
-/*
- * task tracking -- fork/exit
- *
- * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
- */
-
-struct perf_task_event {
-	struct task_struct		*task;
-	struct perf_event_context	*task_ctx;
-
-	struct {
-		struct perf_event_header	header;
-
-		u32				pid;
-		u32				ppid;
-		u32				tid;
-		u32				ptid;
-		u64				time;
-	} event_id;
-};
-
-static void perf_event_task_output(struct perf_event *event,
-				     struct perf_task_event *task_event)
-{
-	struct perf_output_handle handle;
-	struct task_struct *task = task_event->task;
-	int size, ret;
-
-	size  = task_event->event_id.header.size;
-	ret = perf_output_begin(&handle, event, size, 0, 0);
-
-	if (ret)
-		return;
-
-	task_event->event_id.pid = perf_event_pid(event, task);
-	task_event->event_id.ppid = perf_event_pid(event, current);
-
-	task_event->event_id.tid = perf_event_tid(event, task);
-	task_event->event_id.ptid = perf_event_tid(event, current);
-
-	perf_output_put(&handle, task_event->event_id);
-
-	perf_output_end(&handle);
-}
-
-static int perf_event_task_match(struct perf_event *event)
-{
-	if (event->state < PERF_EVENT_STATE_INACTIVE)
-		return 0;
-
-	if (event->cpu != -1 && event->cpu != smp_processor_id())
-		return 0;
-
-	if (event->attr.comm || event->attr.mmap ||
-	    event->attr.mmap_data || event->attr.task)
-		return 1;
-
-	return 0;
-}
-
-static void perf_event_task_ctx(struct perf_event_context *ctx,
-				  struct perf_task_event *task_event)
-{
-	struct perf_event *event;
-
-	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
-		if (perf_event_task_match(event))
-			perf_event_task_output(event, task_event);
-	}
-}
-
-static void perf_event_task_event(struct perf_task_event *task_event)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx = task_event->task_ctx;
-
-	rcu_read_lock();
-	cpuctx = &get_cpu_var(perf_cpu_context);
-	perf_event_task_ctx(&cpuctx->ctx, task_event);
-	if (!ctx)
-		ctx = rcu_dereference(current->perf_event_ctxp);
-	if (ctx)
-		perf_event_task_ctx(ctx, task_event);
-	put_cpu_var(perf_cpu_context);
-	rcu_read_unlock();
-}
-
-static void perf_event_task(struct task_struct *task,
-			      struct perf_event_context *task_ctx,
-			      int new)
-{
-	struct perf_task_event task_event;
-
-	if (!atomic_read(&nr_comm_events) &&
-	    !atomic_read(&nr_mmap_events) &&
-	    !atomic_read(&nr_task_events))
-		return;
-
-	task_event = (struct perf_task_event){
-		.task	  = task,
-		.task_ctx = task_ctx,
-		.event_id    = {
-			.header = {
-				.type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
-				.misc = 0,
-				.size = sizeof(task_event.event_id),
-			},
-			/* .pid  */
-			/* .ppid */
-			/* .tid  */
-			/* .ptid */
-			.time = perf_clock(),
-		},
-	};
-
-	perf_event_task_event(&task_event);
-}
-
-void perf_event_fork(struct task_struct *task)
-{
-	perf_event_task(task, NULL, 1);
-}
-
-/*
- * comm tracking
- */
-
-struct perf_comm_event {
-	struct task_struct	*task;
-	char			*comm;
-	int			comm_size;
-
-	struct {
-		struct perf_event_header	header;
-
-		u32				pid;
-		u32				tid;
-	} event_id;
-};
-
-static void perf_event_comm_output(struct perf_event *event,
-				     struct perf_comm_event *comm_event)
-{
-	struct perf_output_handle handle;
-	int size = comm_event->event_id.header.size;
-	int ret = perf_output_begin(&handle, event, size, 0, 0);
-
-	if (ret)
-		return;
-
-	comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
-	comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
-
-	perf_output_put(&handle, comm_event->event_id);
-	perf_output_copy(&handle, comm_event->comm,
-				   comm_event->comm_size);
-	perf_output_end(&handle);
-}
-
-static int perf_event_comm_match(struct perf_event *event)
-{
-	if (event->state < PERF_EVENT_STATE_INACTIVE)
-		return 0;
-
-	if (event->cpu != -1 && event->cpu != smp_processor_id())
-		return 0;
-
-	if (event->attr.comm)
-		return 1;
-
-	return 0;
-}
-
-static void perf_event_comm_ctx(struct perf_event_context *ctx,
-				  struct perf_comm_event *comm_event)
-{
-	struct perf_event *event;
-
-	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
-		if (perf_event_comm_match(event))
-			perf_event_comm_output(event, comm_event);
-	}
-}
-
-static void perf_event_comm_event(struct perf_comm_event *comm_event)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx;
-	unsigned int size;
-	char comm[TASK_COMM_LEN];
-
-	memset(comm, 0, sizeof(comm));
-	strlcpy(comm, comm_event->task->comm, sizeof(comm));
-	size = ALIGN(strlen(comm)+1, sizeof(u64));
-
-	comm_event->comm = comm;
-	comm_event->comm_size = size;
-
-	comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
-
-	rcu_read_lock();
-	cpuctx = &get_cpu_var(perf_cpu_context);
-	perf_event_comm_ctx(&cpuctx->ctx, comm_event);
-	ctx = rcu_dereference(current->perf_event_ctxp);
-	if (ctx)
-		perf_event_comm_ctx(ctx, comm_event);
-	put_cpu_var(perf_cpu_context);
-	rcu_read_unlock();
-}
-
-void perf_event_comm(struct task_struct *task)
-{
-	struct perf_comm_event comm_event;
-
-	if (task->perf_event_ctxp)
-		perf_event_enable_on_exec(task);
-
-	if (!atomic_read(&nr_comm_events))
-		return;
-
-	comm_event = (struct perf_comm_event){
-		.task	= task,
-		/* .comm      */
-		/* .comm_size */
-		.event_id  = {
-			.header = {
-				.type = PERF_RECORD_COMM,
-				.misc = 0,
-				/* .size */
-			},
-			/* .pid */
-			/* .tid */
-		},
-	};
-
-	perf_event_comm_event(&comm_event);
-}
-
-/*
- * mmap tracking
- */
-
-struct perf_mmap_event {
-	struct vm_area_struct	*vma;
-
-	const char		*file_name;
-	int			file_size;
-
-	struct {
-		struct perf_event_header	header;
-
-		u32				pid;
-		u32				tid;
-		u64				start;
-		u64				len;
-		u64				pgoff;
-	} event_id;
-};
-
-static void perf_event_mmap_output(struct perf_event *event,
-				     struct perf_mmap_event *mmap_event)
-{
-	struct perf_output_handle handle;
-	int size = mmap_event->event_id.header.size;
-	int ret = perf_output_begin(&handle, event, size, 0, 0);
-
-	if (ret)
-		return;
-
-	mmap_event->event_id.pid = perf_event_pid(event, current);
-	mmap_event->event_id.tid = perf_event_tid(event, current);
-
-	perf_output_put(&handle, mmap_event->event_id);
-	perf_output_copy(&handle, mmap_event->file_name,
-				   mmap_event->file_size);
-	perf_output_end(&handle);
-}
-
-static int perf_event_mmap_match(struct perf_event *event,
-				   struct perf_mmap_event *mmap_event,
-				   int executable)
-{
-	if (event->state < PERF_EVENT_STATE_INACTIVE)
-		return 0;
-
-	if (event->cpu != -1 && event->cpu != smp_processor_id())
-		return 0;
-
-	if ((!executable && event->attr.mmap_data) ||
-	    (executable && event->attr.mmap))
-		return 1;
-
-	return 0;
-}
-
-static void perf_event_mmap_ctx(struct perf_event_context *ctx,
-				  struct perf_mmap_event *mmap_event,
-				  int executable)
-{
-	struct perf_event *event;
-
-	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
-		if (perf_event_mmap_match(event, mmap_event, executable))
-			perf_event_mmap_output(event, mmap_event);
-	}
-}
-
-static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx;
-	struct vm_area_struct *vma = mmap_event->vma;
-	struct file *file = vma->vm_file;
-	unsigned int size;
-	char tmp[16];
-	char *buf = NULL;
-	const char *name;
-
-	memset(tmp, 0, sizeof(tmp));
-
-	if (file) {
-		/*
-		 * d_path works from the end of the buffer backwards, so we
-		 * need to add enough zero bytes after the string to handle
-		 * the 64bit alignment we do later.
-		 */
-		buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
-		if (!buf) {
-			name = strncpy(tmp, "//enomem", sizeof(tmp));
-			goto got_name;
-		}
-		name = d_path(&file->f_path, buf, PATH_MAX);
-		if (IS_ERR(name)) {
-			name = strncpy(tmp, "//toolong", sizeof(tmp));
-			goto got_name;
-		}
-	} else {
-		if (arch_vma_name(mmap_event->vma)) {
-			name = strncpy(tmp, arch_vma_name(mmap_event->vma),
-				       sizeof(tmp));
-			goto got_name;
-		}
-
-		if (!vma->vm_mm) {
-			name = strncpy(tmp, "[vdso]", sizeof(tmp));
-			goto got_name;
-		} else if (vma->vm_start <= vma->vm_mm->start_brk &&
-				vma->vm_end >= vma->vm_mm->brk) {
-			name = strncpy(tmp, "[heap]", sizeof(tmp));
-			goto got_name;
-		} else if (vma->vm_start <= vma->vm_mm->start_stack &&
-				vma->vm_end >= vma->vm_mm->start_stack) {
-			name = strncpy(tmp, "[stack]", sizeof(tmp));
-			goto got_name;
-		}
-
-		name = strncpy(tmp, "//anon", sizeof(tmp));
-		goto got_name;
-	}
-
-got_name:
-	size = ALIGN(strlen(name)+1, sizeof(u64));
-
-	mmap_event->file_name = name;
-	mmap_event->file_size = size;
-
-	mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
-
-	rcu_read_lock();
-	cpuctx = &get_cpu_var(perf_cpu_context);
-	perf_event_mmap_ctx(&cpuctx->ctx, mmap_event, vma->vm_flags & VM_EXEC);
-	ctx = rcu_dereference(current->perf_event_ctxp);
-	if (ctx)
-		perf_event_mmap_ctx(ctx, mmap_event, vma->vm_flags & VM_EXEC);
-	put_cpu_var(perf_cpu_context);
-	rcu_read_unlock();
-
-	kfree(buf);
-}
-
-void perf_event_mmap(struct vm_area_struct *vma)
-{
-	struct perf_mmap_event mmap_event;
-
-	if (!atomic_read(&nr_mmap_events))
-		return;
-
-	mmap_event = (struct perf_mmap_event){
-		.vma	= vma,
-		/* .file_name */
-		/* .file_size */
-		.event_id  = {
-			.header = {
-				.type = PERF_RECORD_MMAP,
-				.misc = PERF_RECORD_MISC_USER,
-				/* .size */
-			},
-			/* .pid */
-			/* .tid */
-			.start  = vma->vm_start,
-			.len    = vma->vm_end - vma->vm_start,
-			.pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
-		},
-	};
-
-	perf_event_mmap_event(&mmap_event);
-}
-
-/*
- * IRQ throttle logging
- */
-
-static void perf_log_throttle(struct perf_event *event, int enable)
-{
-	struct perf_output_handle handle;
-	int ret;
-
-	struct {
-		struct perf_event_header	header;
-		u64				time;
-		u64				id;
-		u64				stream_id;
-	} throttle_event = {
-		.header = {
-			.type = PERF_RECORD_THROTTLE,
-			.misc = 0,
-			.size = sizeof(throttle_event),
-		},
-		.time		= perf_clock(),
-		.id		= primary_event_id(event),
-		.stream_id	= event->id,
-	};
-
-	if (enable)
-		throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
-
-	ret = perf_output_begin(&handle, event, sizeof(throttle_event), 1, 0);
-	if (ret)
-		return;
-
-	perf_output_put(&handle, throttle_event);
-	perf_output_end(&handle);
-}
-
-/*
- * Generic event overflow handling, sampling.
- */
-
-static int __perf_event_overflow(struct perf_event *event, int nmi,
-				   int throttle, struct perf_sample_data *data,
-				   struct pt_regs *regs)
-{
-	int events = atomic_read(&event->event_limit);
-	struct hw_perf_event *hwc = &event->hw;
-	int ret = 0;
-
-	throttle = (throttle && event->pmu->unthrottle != NULL);
-
-	if (!throttle) {
-		hwc->interrupts++;
-	} else {
-		if (hwc->interrupts != MAX_INTERRUPTS) {
-			hwc->interrupts++;
-			if (HZ * hwc->interrupts >
-					(u64)sysctl_perf_event_sample_rate) {
-				hwc->interrupts = MAX_INTERRUPTS;
-				perf_log_throttle(event, 0);
-				ret = 1;
-			}
-		} else {
-			/*
-			 * Keep re-disabling events even though on the previous
-			 * pass we disabled it - just in case we raced with a
-			 * sched-in and the event got enabled again:
-			 */
-			ret = 1;
-		}
-	}
-
-	if (event->attr.freq) {
-		u64 now = perf_clock();
-		s64 delta = now - hwc->freq_time_stamp;
-
-		hwc->freq_time_stamp = now;
-
-		if (delta > 0 && delta < 2*TICK_NSEC)
-			perf_adjust_period(event, delta, hwc->last_period);
-	}
-
-	/*
-	 * XXX event_limit might not quite work as expected on inherited
-	 * events
-	 */
-
-	event->pending_kill = POLL_IN;
-	if (events && atomic_dec_and_test(&event->event_limit)) {
-		ret = 1;
-		event->pending_kill = POLL_HUP;
-		if (nmi) {
-			event->pending_disable = 1;
-			perf_pending_queue(&event->pending,
-					   perf_pending_event);
-		} else
-			perf_event_disable(event);
-	}
-
-	if (event->overflow_handler)
-		event->overflow_handler(event, nmi, data, regs);
-	else
-		perf_event_output(event, nmi, data, regs);
-
-	return ret;
-}
-
-int perf_event_overflow(struct perf_event *event, int nmi,
-			  struct perf_sample_data *data,
-			  struct pt_regs *regs)
-{
-	return __perf_event_overflow(event, nmi, 1, data, regs);
-}
-
-/*
- * Generic software event infrastructure
- */
-
-/*
- * We directly increment event->count and keep a second value in
- * event->hw.period_left to count intervals. This period event
- * is kept in the range [-sample_period, 0] so that we can use the
- * sign as trigger.
- */
-
-static u64 perf_swevent_set_period(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	u64 period = hwc->last_period;
-	u64 nr, offset;
-	s64 old, val;
-
-	hwc->last_period = hwc->sample_period;
-
-again:
-	old = val = local64_read(&hwc->period_left);
-	if (val < 0)
-		return 0;
-
-	nr = div64_u64(period + val, period);
-	offset = nr * period;
-	val -= offset;
-	if (local64_cmpxchg(&hwc->period_left, old, val) != old)
-		goto again;
-
-	return nr;
-}
-
-static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
-				    int nmi, struct perf_sample_data *data,
-				    struct pt_regs *regs)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	int throttle = 0;
-
-	data->period = event->hw.last_period;
-	if (!overflow)
-		overflow = perf_swevent_set_period(event);
-
-	if (hwc->interrupts == MAX_INTERRUPTS)
-		return;
-
-	for (; overflow; overflow--) {
-		if (__perf_event_overflow(event, nmi, throttle,
-					    data, regs)) {
-			/*
-			 * We inhibit the overflow from happening when
-			 * hwc->interrupts == MAX_INTERRUPTS.
-			 */
-			break;
-		}
-		throttle = 1;
-	}
-}
-
-static void perf_swevent_add(struct perf_event *event, u64 nr,
-			       int nmi, struct perf_sample_data *data,
-			       struct pt_regs *regs)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	local64_add(nr, &event->count);
-
-	if (!regs)
-		return;
-
-	if (!hwc->sample_period)
-		return;
-
-	if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
-		return perf_swevent_overflow(event, 1, nmi, data, regs);
-
-	if (local64_add_negative(nr, &hwc->period_left))
-		return;
-
-	perf_swevent_overflow(event, 0, nmi, data, regs);
-}
-
-static int perf_exclude_event(struct perf_event *event,
-			      struct pt_regs *regs)
-{
-	if (regs) {
-		if (event->attr.exclude_user && user_mode(regs))
-			return 1;
-
-		if (event->attr.exclude_kernel && !user_mode(regs))
-			return 1;
-	}
-
-	return 0;
-}
-
-static int perf_swevent_match(struct perf_event *event,
-				enum perf_type_id type,
-				u32 event_id,
-				struct perf_sample_data *data,
-				struct pt_regs *regs)
-{
-	if (event->attr.type != type)
-		return 0;
-
-	if (event->attr.config != event_id)
-		return 0;
-
-	if (perf_exclude_event(event, regs))
-		return 0;
-
-	return 1;
-}
-
-static inline u64 swevent_hash(u64 type, u32 event_id)
-{
-	u64 val = event_id | (type << 32);
-
-	return hash_64(val, SWEVENT_HLIST_BITS);
-}
-
-static inline struct hlist_head *
-__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
-{
-	u64 hash = swevent_hash(type, event_id);
-
-	return &hlist->heads[hash];
-}
-
-/* For the read side: events when they trigger */
-static inline struct hlist_head *
-find_swevent_head_rcu(struct perf_cpu_context *ctx, u64 type, u32 event_id)
-{
-	struct swevent_hlist *hlist;
-
-	hlist = rcu_dereference(ctx->swevent_hlist);
-	if (!hlist)
-		return NULL;
-
-	return __find_swevent_head(hlist, type, event_id);
-}
-
-/* For the event head insertion and removal in the hlist */
-static inline struct hlist_head *
-find_swevent_head(struct perf_cpu_context *ctx, struct perf_event *event)
-{
-	struct swevent_hlist *hlist;
-	u32 event_id = event->attr.config;
-	u64 type = event->attr.type;
-
-	/*
-	 * Event scheduling is always serialized against hlist allocation
-	 * and release. Which makes the protected version suitable here.
-	 * The context lock guarantees that.
-	 */
-	hlist = rcu_dereference_protected(ctx->swevent_hlist,
-					  lockdep_is_held(&event->ctx->lock));
-	if (!hlist)
-		return NULL;
-
-	return __find_swevent_head(hlist, type, event_id);
-}
-
-static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
-				    u64 nr, int nmi,
-				    struct perf_sample_data *data,
-				    struct pt_regs *regs)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event *event;
-	struct hlist_node *node;
-	struct hlist_head *head;
-
-	cpuctx = &__get_cpu_var(perf_cpu_context);
-
-	rcu_read_lock();
-
-	head = find_swevent_head_rcu(cpuctx, type, event_id);
-
-	if (!head)
-		goto end;
-
-	hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
-		if (perf_swevent_match(event, type, event_id, data, regs))
-			perf_swevent_add(event, nr, nmi, data, regs);
-	}
-end:
-	rcu_read_unlock();
-}
-
-int perf_swevent_get_recursion_context(void)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	int rctx;
-
-	if (in_nmi())
-		rctx = 3;
-	else if (in_irq())
-		rctx = 2;
-	else if (in_softirq())
-		rctx = 1;
-	else
-		rctx = 0;
-
-	if (cpuctx->recursion[rctx])
-		return -1;
-
-	cpuctx->recursion[rctx]++;
-	barrier();
-
-	return rctx;
-}
-EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
-
-void inline perf_swevent_put_recursion_context(int rctx)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	barrier();
-	cpuctx->recursion[rctx]--;
-}
-
-void __perf_sw_event(u32 event_id, u64 nr, int nmi,
-			    struct pt_regs *regs, u64 addr)
-{
-	struct perf_sample_data data;
-	int rctx;
-
-	preempt_disable_notrace();
-	rctx = perf_swevent_get_recursion_context();
-	if (rctx < 0)
-		return;
-
-	perf_sample_data_init(&data, addr);
-
-	do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
-
-	perf_swevent_put_recursion_context(rctx);
-	preempt_enable_notrace();
-}
-
-static void perf_swevent_read(struct perf_event *event)
-{
-}
-
-static int perf_swevent_enable(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	struct perf_cpu_context *cpuctx;
-	struct hlist_head *head;
-
-	cpuctx = &__get_cpu_var(perf_cpu_context);
-
-	if (hwc->sample_period) {
-		hwc->last_period = hwc->sample_period;
-		perf_swevent_set_period(event);
-	}
-
-	head = find_swevent_head(cpuctx, event);
-	if (WARN_ON_ONCE(!head))
-		return -EINVAL;
-
-	hlist_add_head_rcu(&event->hlist_entry, head);
-
-	return 0;
-}
-
-static void perf_swevent_disable(struct perf_event *event)
-{
-	hlist_del_rcu(&event->hlist_entry);
-}
-
-static void perf_swevent_void(struct perf_event *event)
-{
-}
-
-static int perf_swevent_int(struct perf_event *event)
-{
-	return 0;
-}
-
-static const struct pmu perf_ops_generic = {
-	.enable		= perf_swevent_enable,
-	.disable	= perf_swevent_disable,
-	.start		= perf_swevent_int,
-	.stop		= perf_swevent_void,
-	.read		= perf_swevent_read,
-	.unthrottle	= perf_swevent_void, /* hwc->interrupts already reset */
-};
-
-/*
- * hrtimer based swevent callback
- */
-
-static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
-{
-	enum hrtimer_restart ret = HRTIMER_RESTART;
-	struct perf_sample_data data;
-	struct pt_regs *regs;
-	struct perf_event *event;
-	u64 period;
-
-	event = container_of(hrtimer, struct perf_event, hw.hrtimer);
-	event->pmu->read(event);
-
-	perf_sample_data_init(&data, 0);
-	data.period = event->hw.last_period;
-	regs = get_irq_regs();
-
-	if (regs && !perf_exclude_event(event, regs)) {
-		if (!(event->attr.exclude_idle && current->pid == 0))
-			if (perf_event_overflow(event, 0, &data, regs))
-				ret = HRTIMER_NORESTART;
-	}
-
-	period = max_t(u64, 10000, event->hw.sample_period);
-	hrtimer_forward_now(hrtimer, ns_to_ktime(period));
-
-	return ret;
-}
-
-static void perf_swevent_start_hrtimer(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-	hwc->hrtimer.function = perf_swevent_hrtimer;
-	if (hwc->sample_period) {
-		u64 period;
-
-		if (hwc->remaining) {
-			if (hwc->remaining < 0)
-				period = 10000;
-			else
-				period = hwc->remaining;
-			hwc->remaining = 0;
-		} else {
-			period = max_t(u64, 10000, hwc->sample_period);
-		}
-		__hrtimer_start_range_ns(&hwc->hrtimer,
-				ns_to_ktime(period), 0,
-				HRTIMER_MODE_REL, 0);
-	}
-}
-
-static void perf_swevent_cancel_hrtimer(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	if (hwc->sample_period) {
-		ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
-		hwc->remaining = ktime_to_ns(remaining);
-
-		hrtimer_cancel(&hwc->hrtimer);
-	}
-}
-
-/*
- * Software event: cpu wall time clock
- */
-
-static void cpu_clock_perf_event_update(struct perf_event *event)
-{
-	int cpu = raw_smp_processor_id();
-	s64 prev;
-	u64 now;
-
-	now = cpu_clock(cpu);
-	prev = local64_xchg(&event->hw.prev_count, now);
-	local64_add(now - prev, &event->count);
-}
-
-static int cpu_clock_perf_event_enable(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	int cpu = raw_smp_processor_id();
-
-	local64_set(&hwc->prev_count, cpu_clock(cpu));
-	perf_swevent_start_hrtimer(event);
-
-	return 0;
-}
-
-static void cpu_clock_perf_event_disable(struct perf_event *event)
-{
-	perf_swevent_cancel_hrtimer(event);
-	cpu_clock_perf_event_update(event);
-}
-
-static void cpu_clock_perf_event_read(struct perf_event *event)
-{
-	cpu_clock_perf_event_update(event);
-}
-
-static const struct pmu perf_ops_cpu_clock = {
-	.enable		= cpu_clock_perf_event_enable,
-	.disable	= cpu_clock_perf_event_disable,
-	.read		= cpu_clock_perf_event_read,
-};
-
-/*
- * Software event: task time clock
- */
-
-static void task_clock_perf_event_update(struct perf_event *event, u64 now)
-{
-	u64 prev;
-	s64 delta;
-
-	prev = local64_xchg(&event->hw.prev_count, now);
-	delta = now - prev;
-	local64_add(delta, &event->count);
-}
-
-static int task_clock_perf_event_enable(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	u64 now;
-
-	now = event->ctx->time;
-
-	local64_set(&hwc->prev_count, now);
-
-	perf_swevent_start_hrtimer(event);
-
-	return 0;
-}
-
-static void task_clock_perf_event_disable(struct perf_event *event)
-{
-	perf_swevent_cancel_hrtimer(event);
-	task_clock_perf_event_update(event, event->ctx->time);
-
-}
-
-static void task_clock_perf_event_read(struct perf_event *event)
-{
-	u64 time;
-
-	if (!in_nmi()) {
-		update_context_time(event->ctx);
-		time = event->ctx->time;
-	} else {
-		u64 now = perf_clock();
-		u64 delta = now - event->ctx->timestamp;
-		time = event->ctx->time + delta;
-	}
-
-	task_clock_perf_event_update(event, time);
-}
-
-static const struct pmu perf_ops_task_clock = {
-	.enable		= task_clock_perf_event_enable,
-	.disable	= task_clock_perf_event_disable,
-	.read		= task_clock_perf_event_read,
-};
-
-/* Deref the hlist from the update side */
-static inline struct swevent_hlist *
-swevent_hlist_deref(struct perf_cpu_context *cpuctx)
-{
-	return rcu_dereference_protected(cpuctx->swevent_hlist,
-					 lockdep_is_held(&cpuctx->hlist_mutex));
-}
-
-static void swevent_hlist_release_rcu(struct rcu_head *rcu_head)
-{
-	struct swevent_hlist *hlist;
-
-	hlist = container_of(rcu_head, struct swevent_hlist, rcu_head);
-	kfree(hlist);
-}
-
-static void swevent_hlist_release(struct perf_cpu_context *cpuctx)
-{
-	struct swevent_hlist *hlist = swevent_hlist_deref(cpuctx);
-
-	if (!hlist)
-		return;
-
-	rcu_assign_pointer(cpuctx->swevent_hlist, NULL);
-	call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu);
-}
-
-static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
-{
-	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
-
-	mutex_lock(&cpuctx->hlist_mutex);
-
-	if (!--cpuctx->hlist_refcount)
-		swevent_hlist_release(cpuctx);
-
-	mutex_unlock(&cpuctx->hlist_mutex);
-}
-
-static void swevent_hlist_put(struct perf_event *event)
-{
-	int cpu;
-
-	if (event->cpu != -1) {
-		swevent_hlist_put_cpu(event, event->cpu);
-		return;
-	}
-
-	for_each_possible_cpu(cpu)
-		swevent_hlist_put_cpu(event, cpu);
-}
-
-static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
-{
-	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
-	int err = 0;
-
-	mutex_lock(&cpuctx->hlist_mutex);
-
-	if (!swevent_hlist_deref(cpuctx) && cpu_online(cpu)) {
-		struct swevent_hlist *hlist;
-
-		hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
-		if (!hlist) {
-			err = -ENOMEM;
-			goto exit;
-		}
-		rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
-	}
-	cpuctx->hlist_refcount++;
- exit:
-	mutex_unlock(&cpuctx->hlist_mutex);
-
-	return err;
-}
-
-static int swevent_hlist_get(struct perf_event *event)
-{
-	int err;
-	int cpu, failed_cpu;
-
-	if (event->cpu != -1)
-		return swevent_hlist_get_cpu(event, event->cpu);
-
-	get_online_cpus();
-	for_each_possible_cpu(cpu) {
-		err = swevent_hlist_get_cpu(event, cpu);
-		if (err) {
-			failed_cpu = cpu;
-			goto fail;
-		}
-	}
-	put_online_cpus();
-
-	return 0;
- fail:
-	for_each_possible_cpu(cpu) {
-		if (cpu == failed_cpu)
-			break;
-		swevent_hlist_put_cpu(event, cpu);
-	}
-
-	put_online_cpus();
-	return err;
-}
-
-#ifdef CONFIG_EVENT_TRACING
-
-static const struct pmu perf_ops_tracepoint = {
-	.enable		= perf_trace_enable,
-	.disable	= perf_trace_disable,
-	.start		= perf_swevent_int,
-	.stop		= perf_swevent_void,
-	.read		= perf_swevent_read,
-	.unthrottle	= perf_swevent_void,
-};
-
-static int perf_tp_filter_match(struct perf_event *event,
-				struct perf_sample_data *data)
-{
-	void *record = data->raw->data;
-
-	if (likely(!event->filter) || filter_match_preds(event->filter, record))
-		return 1;
-	return 0;
-}
-
-static int perf_tp_event_match(struct perf_event *event,
-				struct perf_sample_data *data,
-				struct pt_regs *regs)
-{
-	/*
-	 * All tracepoints are from kernel-space.
-	 */
-	if (event->attr.exclude_kernel)
-		return 0;
-
-	if (!perf_tp_filter_match(event, data))
-		return 0;
-
-	return 1;
-}
-
-void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
-		   struct pt_regs *regs, struct hlist_head *head, int rctx)
-{
-	struct perf_sample_data data;
-	struct perf_event *event;
-	struct hlist_node *node;
-
-	struct perf_raw_record raw = {
-		.size = entry_size,
-		.data = record,
-	};
-
-	perf_sample_data_init(&data, addr);
-	data.raw = &raw;
-
-	hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
-		if (perf_tp_event_match(event, &data, regs))
-			perf_swevent_add(event, count, 1, &data, regs);
-	}
-
-	perf_swevent_put_recursion_context(rctx);
-}
-EXPORT_SYMBOL_GPL(perf_tp_event);
-
-static void tp_perf_event_destroy(struct perf_event *event)
-{
-	perf_trace_destroy(event);
-}
-
-static const struct pmu *tp_perf_event_init(struct perf_event *event)
-{
-	int err;
-
-	/*
-	 * Raw tracepoint data is a severe data leak, only allow root to
-	 * have these.
-	 */
-	if ((event->attr.sample_type & PERF_SAMPLE_RAW) &&
-			perf_paranoid_tracepoint_raw() &&
-			!capable(CAP_SYS_ADMIN))
-		return ERR_PTR(-EPERM);
-
-	err = perf_trace_init(event);
-	if (err)
-		return NULL;
-
-	event->destroy = tp_perf_event_destroy;
-
-	return &perf_ops_tracepoint;
-}
-
-static int perf_event_set_filter(struct perf_event *event, void __user *arg)
-{
-	char *filter_str;
-	int ret;
-
-	if (event->attr.type != PERF_TYPE_TRACEPOINT)
-		return -EINVAL;
-
-	filter_str = strndup_user(arg, PAGE_SIZE);
-	if (IS_ERR(filter_str))
-		return PTR_ERR(filter_str);
-
-	ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
-
-	kfree(filter_str);
-	return ret;
-}
-
-static void perf_event_free_filter(struct perf_event *event)
-{
-	ftrace_profile_free_filter(event);
-}
-
-#else
-
-static const struct pmu *tp_perf_event_init(struct perf_event *event)
-{
-	return NULL;
-}
-
-static int perf_event_set_filter(struct perf_event *event, void __user *arg)
-{
-	return -ENOENT;
-}
-
-static void perf_event_free_filter(struct perf_event *event)
-{
-}
-
-#endif /* CONFIG_EVENT_TRACING */
-
-#ifdef CONFIG_HAVE_HW_BREAKPOINT
-static void bp_perf_event_destroy(struct perf_event *event)
-{
-	release_bp_slot(event);
-}
-
-static const struct pmu *bp_perf_event_init(struct perf_event *bp)
-{
-	int err;
-
-	err = register_perf_hw_breakpoint(bp);
-	if (err)
-		return ERR_PTR(err);
-
-	bp->destroy = bp_perf_event_destroy;
-
-	return &perf_ops_bp;
-}
-
-void perf_bp_event(struct perf_event *bp, void *data)
-{
-	struct perf_sample_data sample;
-	struct pt_regs *regs = data;
-
-	perf_sample_data_init(&sample, bp->attr.bp_addr);
-
-	if (!perf_exclude_event(bp, regs))
-		perf_swevent_add(bp, 1, 1, &sample, regs);
-}
-#else
-static const struct pmu *bp_perf_event_init(struct perf_event *bp)
-{
-	return NULL;
-}
-
-void perf_bp_event(struct perf_event *bp, void *regs)
-{
-}
-#endif
-
-atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
-
-static void sw_perf_event_destroy(struct perf_event *event)
-{
-	u64 event_id = event->attr.config;
-
-	WARN_ON(event->parent);
-
-	atomic_dec(&perf_swevent_enabled[event_id]);
-	swevent_hlist_put(event);
-}
-
-static const struct pmu *sw_perf_event_init(struct perf_event *event)
-{
-	const struct pmu *pmu = NULL;
-	u64 event_id = event->attr.config;
-
-	/*
-	 * Software events (currently) can't in general distinguish
-	 * between user, kernel and hypervisor events.
-	 * However, context switches and cpu migrations are considered
-	 * to be kernel events, and page faults are never hypervisor
-	 * events.
-	 */
-	switch (event_id) {
-	case PERF_COUNT_SW_CPU_CLOCK:
-		pmu = &perf_ops_cpu_clock;
-
-		break;
-	case PERF_COUNT_SW_TASK_CLOCK:
-		/*
-		 * If the user instantiates this as a per-cpu event,
-		 * use the cpu_clock event instead.
-		 */
-		if (event->ctx->task)
-			pmu = &perf_ops_task_clock;
-		else
-			pmu = &perf_ops_cpu_clock;
-
-		break;
-	case PERF_COUNT_SW_PAGE_FAULTS:
-	case PERF_COUNT_SW_PAGE_FAULTS_MIN:
-	case PERF_COUNT_SW_PAGE_FAULTS_MAJ:
-	case PERF_COUNT_SW_CONTEXT_SWITCHES:
-	case PERF_COUNT_SW_CPU_MIGRATIONS:
-	case PERF_COUNT_SW_ALIGNMENT_FAULTS:
-	case PERF_COUNT_SW_EMULATION_FAULTS:
-		if (!event->parent) {
-			int err;
-
-			err = swevent_hlist_get(event);
-			if (err)
-				return ERR_PTR(err);
-
-			atomic_inc(&perf_swevent_enabled[event_id]);
-			event->destroy = sw_perf_event_destroy;
-		}
-		pmu = &perf_ops_generic;
-		break;
-	}
-
-	return pmu;
-}
-
-/*
- * Allocate and initialize a event structure
- */
-static struct perf_event *
-perf_event_alloc(struct perf_event_attr *attr,
-		   int cpu,
-		   struct perf_event_context *ctx,
-		   struct perf_event *group_leader,
-		   struct perf_event *parent_event,
-		   perf_overflow_handler_t overflow_handler,
-		   gfp_t gfpflags)
-{
-	const struct pmu *pmu;
-	struct perf_event *event;
-	struct hw_perf_event *hwc;
-	long err;
-
-	event = kzalloc(sizeof(*event), gfpflags);
-	if (!event)
-		return ERR_PTR(-ENOMEM);
-
-	/*
-	 * Single events are their own group leaders, with an
-	 * empty sibling list:
-	 */
-	if (!group_leader)
-		group_leader = event;
-
-	mutex_init(&event->child_mutex);
-	INIT_LIST_HEAD(&event->child_list);
-
-	INIT_LIST_HEAD(&event->group_entry);
-	INIT_LIST_HEAD(&event->event_entry);
-	INIT_LIST_HEAD(&event->sibling_list);
-	init_waitqueue_head(&event->waitq);
-
-	mutex_init(&event->mmap_mutex);
-
-	event->cpu		= cpu;
-	event->attr		= *attr;
-	event->group_leader	= group_leader;
-	event->pmu		= NULL;
-	event->ctx		= ctx;
-	event->oncpu		= -1;
-
-	event->parent		= parent_event;
-
-	event->ns		= get_pid_ns(current->nsproxy->pid_ns);
-	event->id		= atomic64_inc_return(&perf_event_id);
-
-	event->state		= PERF_EVENT_STATE_INACTIVE;
-
-	if (!overflow_handler && parent_event)
-		overflow_handler = parent_event->overflow_handler;
-	
-	event->overflow_handler	= overflow_handler;
-
-	if (attr->disabled)
-		event->state = PERF_EVENT_STATE_OFF;
-
-	pmu = NULL;
-
-	hwc = &event->hw;
-	hwc->sample_period = attr->sample_period;
-	if (attr->freq && attr->sample_freq)
-		hwc->sample_period = 1;
-	hwc->last_period = hwc->sample_period;
-
-	local64_set(&hwc->period_left, hwc->sample_period);
-
-	/*
-	 * we currently do not support PERF_FORMAT_GROUP on inherited events
-	 */
-	if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
-		goto done;
-
-	switch (attr->type) {
-	case PERF_TYPE_RAW:
-	case PERF_TYPE_HARDWARE:
-	case PERF_TYPE_HW_CACHE:
-		pmu = hw_perf_event_init(event);
-		break;
-
-	case PERF_TYPE_SOFTWARE:
-		pmu = sw_perf_event_init(event);
-		break;
-
-	case PERF_TYPE_TRACEPOINT:
-		pmu = tp_perf_event_init(event);
-		break;
-
-	case PERF_TYPE_BREAKPOINT:
-		pmu = bp_perf_event_init(event);
-		break;
-
-
-	default:
-		break;
-	}
-done:
-	err = 0;
-	if (!pmu)
-		err = -EINVAL;
-	else if (IS_ERR(pmu))
-		err = PTR_ERR(pmu);
-
-	if (err) {
-		if (event->ns)
-			put_pid_ns(event->ns);
-		kfree(event);
-		return ERR_PTR(err);
-	}
-
-	event->pmu = pmu;
-
-	if (!event->parent) {
-		atomic_inc(&nr_events);
-		if (event->attr.mmap || event->attr.mmap_data)
-			atomic_inc(&nr_mmap_events);
-		if (event->attr.comm)
-			atomic_inc(&nr_comm_events);
-		if (event->attr.task)
-			atomic_inc(&nr_task_events);
-	}
-
-	return event;
-}
-
-static int perf_copy_attr(struct perf_event_attr __user *uattr,
-			  struct perf_event_attr *attr)
-{
-	u32 size;
-	int ret;
-
-	if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
-		return -EFAULT;
-
-	/*
-	 * zero the full structure, so that a short copy will be nice.
-	 */
-	memset(attr, 0, sizeof(*attr));
-
-	ret = get_user(size, &uattr->size);
-	if (ret)
-		return ret;
-
-	if (size > PAGE_SIZE)	/* silly large */
-		goto err_size;
-
-	if (!size)		/* abi compat */
-		size = PERF_ATTR_SIZE_VER0;
-
-	if (size < PERF_ATTR_SIZE_VER0)
-		goto err_size;
-
-	/*
-	 * If we're handed a bigger struct than we know of,
-	 * ensure all the unknown bits are 0 - i.e. new
-	 * user-space does not rely on any kernel feature
-	 * extensions we dont know about yet.
-	 */
-	if (size > sizeof(*attr)) {
-		unsigned char __user *addr;
-		unsigned char __user *end;
-		unsigned char val;
-
-		addr = (void __user *)uattr + sizeof(*attr);
-		end  = (void __user *)uattr + size;
-
-		for (; addr < end; addr++) {
-			ret = get_user(val, addr);
-			if (ret)
-				return ret;
-			if (val)
-				goto err_size;
-		}
-		size = sizeof(*attr);
-	}
-
-	ret = copy_from_user(attr, uattr, size);
-	if (ret)
-		return -EFAULT;
-
-	/*
-	 * If the type exists, the corresponding creation will verify
-	 * the attr->config.
-	 */
-	if (attr->type >= PERF_TYPE_MAX)
-		return -EINVAL;
-
-	if (attr->__reserved_1)
-		return -EINVAL;
-
-	if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
-		return -EINVAL;
-
-	if (attr->read_format & ~(PERF_FORMAT_MAX-1))
-		return -EINVAL;
-
-out:
-	return ret;
-
-err_size:
-	put_user(sizeof(*attr), &uattr->size);
-	ret = -E2BIG;
-	goto out;
-}
-
-static int
-perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
-{
-	struct perf_buffer *buffer = NULL, *old_buffer = NULL;
-	int ret = -EINVAL;
-
-	if (!output_event)
-		goto set;
-
-	/* don't allow circular references */
-	if (event == output_event)
-		goto out;
-
-	/*
-	 * Don't allow cross-cpu buffers
-	 */
-	if (output_event->cpu != event->cpu)
-		goto out;
-
-	/*
-	 * If its not a per-cpu buffer, it must be the same task.
-	 */
-	if (output_event->cpu == -1 && output_event->ctx != event->ctx)
-		goto out;
-
-set:
-	mutex_lock(&event->mmap_mutex);
-	/* Can't redirect output if we've got an active mmap() */
-	if (atomic_read(&event->mmap_count))
-		goto unlock;
-
-	if (output_event) {
-		/* get the buffer we want to redirect to */
-		buffer = perf_buffer_get(output_event);
-		if (!buffer)
-			goto unlock;
-	}
-
-	old_buffer = event->buffer;
-	rcu_assign_pointer(event->buffer, buffer);
-	ret = 0;
-unlock:
-	mutex_unlock(&event->mmap_mutex);
-
-	if (old_buffer)
-		perf_buffer_put(old_buffer);
-out:
-	return ret;
-}
-
-/**
- * sys_perf_event_open - open a performance event, associate it to a task/cpu
- *
- * @attr_uptr:	event_id type attributes for monitoring/sampling
- * @pid:		target pid
- * @cpu:		target cpu
- * @group_fd:		group leader event fd
- */
-SYSCALL_DEFINE5(perf_event_open,
-		struct perf_event_attr __user *, attr_uptr,
-		pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
-{
-	struct perf_event *event, *group_leader = NULL, *output_event = NULL;
-	struct perf_event_attr attr;
-	struct perf_event_context *ctx;
-	struct file *event_file = NULL;
-	struct file *group_file = NULL;
-	int event_fd;
-	int fput_needed = 0;
-	int err;
-
-	/* for future expandability... */
-	if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT))
-		return -EINVAL;
-
-	err = perf_copy_attr(attr_uptr, &attr);
-	if (err)
-		return err;
-
-	if (!attr.exclude_kernel) {
-		if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
-	}
-
-	if (attr.freq) {
-		if (attr.sample_freq > sysctl_perf_event_sample_rate)
-			return -EINVAL;
-	}
-
-	event_fd = get_unused_fd_flags(O_RDWR);
-	if (event_fd < 0)
-		return event_fd;
-
-	/*
-	 * Get the target context (task or percpu):
-	 */
-	ctx = find_get_context(pid, cpu);
-	if (IS_ERR(ctx)) {
-		err = PTR_ERR(ctx);
-		goto err_fd;
-	}
-
-	if (group_fd != -1) {
-		group_leader = perf_fget_light(group_fd, &fput_needed);
-		if (IS_ERR(group_leader)) {
-			err = PTR_ERR(group_leader);
-			goto err_put_context;
-		}
-		group_file = group_leader->filp;
-		if (flags & PERF_FLAG_FD_OUTPUT)
-			output_event = group_leader;
-		if (flags & PERF_FLAG_FD_NO_GROUP)
-			group_leader = NULL;
-	}
-
-	/*
-	 * Look up the group leader (we will attach this event to it):
-	 */
-	if (group_leader) {
-		err = -EINVAL;
-
-		/*
-		 * Do not allow a recursive hierarchy (this new sibling
-		 * becoming part of another group-sibling):
-		 */
-		if (group_leader->group_leader != group_leader)
-			goto err_put_context;
-		/*
-		 * Do not allow to attach to a group in a different
-		 * task or CPU context:
-		 */
-		if (group_leader->ctx != ctx)
-			goto err_put_context;
-		/*
-		 * Only a group leader can be exclusive or pinned
-		 */
-		if (attr.exclusive || attr.pinned)
-			goto err_put_context;
-	}
-
-	event = perf_event_alloc(&attr, cpu, ctx, group_leader,
-				     NULL, NULL, GFP_KERNEL);
-	if (IS_ERR(event)) {
-		err = PTR_ERR(event);
-		goto err_put_context;
-	}
-
-	if (output_event) {
-		err = perf_event_set_output(event, output_event);
-		if (err)
-			goto err_free_put_context;
-	}
-
-	event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
-	if (IS_ERR(event_file)) {
-		err = PTR_ERR(event_file);
-		goto err_free_put_context;
-	}
-
-	event->filp = event_file;
-	WARN_ON_ONCE(ctx->parent_ctx);
-	mutex_lock(&ctx->mutex);
-	perf_install_in_context(ctx, event, cpu);
-	++ctx->generation;
-	mutex_unlock(&ctx->mutex);
-
-	event->owner = current;
-	get_task_struct(current);
-	mutex_lock(&current->perf_event_mutex);
-	list_add_tail(&event->owner_entry, &current->perf_event_list);
-	mutex_unlock(&current->perf_event_mutex);
-
-	/*
-	 * Drop the reference on the group_event after placing the
-	 * new event on the sibling_list. This ensures destruction
-	 * of the group leader will find the pointer to itself in
-	 * perf_group_detach().
-	 */
-	fput_light(group_file, fput_needed);
-	fd_install(event_fd, event_file);
-	return event_fd;
-
-err_free_put_context:
-	free_event(event);
-err_put_context:
-	fput_light(group_file, fput_needed);
-	put_ctx(ctx);
-err_fd:
-	put_unused_fd(event_fd);
-	return err;
-}
-
-/**
- * perf_event_create_kernel_counter
- *
- * @attr: attributes of the counter to create
- * @cpu: cpu in which the counter is bound
- * @pid: task to profile
- */
-struct perf_event *
-perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
-				 pid_t pid,
-				 perf_overflow_handler_t overflow_handler)
-{
-	struct perf_event *event;
-	struct perf_event_context *ctx;
-	int err;
-
-	/*
-	 * Get the target context (task or percpu):
-	 */
-
-	ctx = find_get_context(pid, cpu);
-	if (IS_ERR(ctx)) {
-		err = PTR_ERR(ctx);
-		goto err_exit;
-	}
-
-	event = perf_event_alloc(attr, cpu, ctx, NULL,
-				 NULL, overflow_handler, GFP_KERNEL);
-	if (IS_ERR(event)) {
-		err = PTR_ERR(event);
-		goto err_put_context;
-	}
-
-	event->filp = NULL;
-	WARN_ON_ONCE(ctx->parent_ctx);
-	mutex_lock(&ctx->mutex);
-	perf_install_in_context(ctx, event, cpu);
-	++ctx->generation;
-	mutex_unlock(&ctx->mutex);
-
-	event->owner = current;
-	get_task_struct(current);
-	mutex_lock(&current->perf_event_mutex);
-	list_add_tail(&event->owner_entry, &current->perf_event_list);
-	mutex_unlock(&current->perf_event_mutex);
-
-	return event;
-
- err_put_context:
-	put_ctx(ctx);
- err_exit:
-	return ERR_PTR(err);
-}
-EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
-
-/*
- * inherit a event from parent task to child task:
- */
-static struct perf_event *
-inherit_event(struct perf_event *parent_event,
-	      struct task_struct *parent,
-	      struct perf_event_context *parent_ctx,
-	      struct task_struct *child,
-	      struct perf_event *group_leader,
-	      struct perf_event_context *child_ctx)
-{
-	struct perf_event *child_event;
-
-	/*
-	 * Instead of creating recursive hierarchies of events,
-	 * we link inherited events back to the original parent,
-	 * which has a filp for sure, which we use as the reference
-	 * count:
-	 */
-	if (parent_event->parent)
-		parent_event = parent_event->parent;
-
-	child_event = perf_event_alloc(&parent_event->attr,
-					   parent_event->cpu, child_ctx,
-					   group_leader, parent_event,
-					   NULL, GFP_KERNEL);
-	if (IS_ERR(child_event))
-		return child_event;
-	get_ctx(child_ctx);
-
-	/*
-	 * Make the child state follow the state of the parent event,
-	 * not its attr.disabled bit.  We hold the parent's mutex,
-	 * so we won't race with perf_event_{en, dis}able_family.
-	 */
-	if (parent_event->state >= PERF_EVENT_STATE_INACTIVE)
-		child_event->state = PERF_EVENT_STATE_INACTIVE;
-	else
-		child_event->state = PERF_EVENT_STATE_OFF;
-
-	if (parent_event->attr.freq) {
-		u64 sample_period = parent_event->hw.sample_period;
-		struct hw_perf_event *hwc = &child_event->hw;
-
-		hwc->sample_period = sample_period;
-		hwc->last_period   = sample_period;
-
-		local64_set(&hwc->period_left, sample_period);
-	}
-
-	child_event->overflow_handler = parent_event->overflow_handler;
-
-	/*
-	 * Link it up in the child's context:
-	 */
-	add_event_to_ctx(child_event, child_ctx);
-
-	/*
-	 * Get a reference to the parent filp - we will fput it
-	 * when the child event exits. This is safe to do because
-	 * we are in the parent and we know that the filp still
-	 * exists and has a nonzero count:
-	 */
-	atomic_long_inc(&parent_event->filp->f_count);
-
-	/*
-	 * Link this into the parent event's child list
-	 */
-	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
-	mutex_lock(&parent_event->child_mutex);
-	list_add_tail(&child_event->child_list, &parent_event->child_list);
-	mutex_unlock(&parent_event->child_mutex);
-
-	return child_event;
-}
-
-static int inherit_group(struct perf_event *parent_event,
-	      struct task_struct *parent,
-	      struct perf_event_context *parent_ctx,
-	      struct task_struct *child,
-	      struct perf_event_context *child_ctx)
-{
-	struct perf_event *leader;
-	struct perf_event *sub;
-	struct perf_event *child_ctr;
-
-	leader = inherit_event(parent_event, parent, parent_ctx,
-				 child, NULL, child_ctx);
-	if (IS_ERR(leader))
-		return PTR_ERR(leader);
-	list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
-		child_ctr = inherit_event(sub, parent, parent_ctx,
-					    child, leader, child_ctx);
-		if (IS_ERR(child_ctr))
-			return PTR_ERR(child_ctr);
-	}
-	return 0;
-}
-
-static void sync_child_event(struct perf_event *child_event,
-			       struct task_struct *child)
-{
-	struct perf_event *parent_event = child_event->parent;
-	u64 child_val;
-
-	if (child_event->attr.inherit_stat)
-		perf_event_read_event(child_event, child);
-
-	child_val = perf_event_count(child_event);
-
-	/*
-	 * Add back the child's count to the parent's count:
-	 */
-	atomic64_add(child_val, &parent_event->child_count);
-	atomic64_add(child_event->total_time_enabled,
-		     &parent_event->child_total_time_enabled);
-	atomic64_add(child_event->total_time_running,
-		     &parent_event->child_total_time_running);
-
-	/*
-	 * Remove this event from the parent's list
-	 */
-	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
-	mutex_lock(&parent_event->child_mutex);
-	list_del_init(&child_event->child_list);
-	mutex_unlock(&parent_event->child_mutex);
-
-	/*
-	 * Release the parent event, if this was the last
-	 * reference to it.
-	 */
-	fput(parent_event->filp);
-}
-
-static void
-__perf_event_exit_task(struct perf_event *child_event,
-			 struct perf_event_context *child_ctx,
-			 struct task_struct *child)
-{
-	struct perf_event *parent_event;
-
-	perf_event_remove_from_context(child_event);
-
-	parent_event = child_event->parent;
-	/*
-	 * It can happen that parent exits first, and has events
-	 * that are still around due to the child reference. These
-	 * events need to be zapped - but otherwise linger.
-	 */
-	if (parent_event) {
-		sync_child_event(child_event, child);
-		free_event(child_event);
-	}
-}
-
-/*
- * When a child task exits, feed back event values to parent events.
- */
-void perf_event_exit_task(struct task_struct *child)
-{
-	struct perf_event *child_event, *tmp;
-	struct perf_event_context *child_ctx;
-	unsigned long flags;
-
-	if (likely(!child->perf_event_ctxp)) {
-		perf_event_task(child, NULL, 0);
-		return;
-	}
-
-	local_irq_save(flags);
-	/*
-	 * We can't reschedule here because interrupts are disabled,
-	 * and either child is current or it is a task that can't be
-	 * scheduled, so we are now safe from rescheduling changing
-	 * our context.
-	 */
-	child_ctx = child->perf_event_ctxp;
-	__perf_event_task_sched_out(child_ctx);
-
-	/*
-	 * Take the context lock here so that if find_get_context is
-	 * reading child->perf_event_ctxp, we wait until it has
-	 * incremented the context's refcount before we do put_ctx below.
-	 */
-	raw_spin_lock(&child_ctx->lock);
-	child->perf_event_ctxp = NULL;
-	/*
-	 * If this context is a clone; unclone it so it can't get
-	 * swapped to another process while we're removing all
-	 * the events from it.
-	 */
-	unclone_ctx(child_ctx);
-	update_context_time(child_ctx);
-	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
-
-	/*
-	 * Report the task dead after unscheduling the events so that we
-	 * won't get any samples after PERF_RECORD_EXIT. We can however still
-	 * get a few PERF_RECORD_READ events.
-	 */
-	perf_event_task(child, child_ctx, 0);
-
-	/*
-	 * We can recurse on the same lock type through:
-	 *
-	 *   __perf_event_exit_task()
-	 *     sync_child_event()
-	 *       fput(parent_event->filp)
-	 *         perf_release()
-	 *           mutex_lock(&ctx->mutex)
-	 *
-	 * But since its the parent context it won't be the same instance.
-	 */
-	mutex_lock(&child_ctx->mutex);
-
-again:
-	list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
-				 group_entry)
-		__perf_event_exit_task(child_event, child_ctx, child);
-
-	list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
-				 group_entry)
-		__perf_event_exit_task(child_event, child_ctx, child);
-
-	/*
-	 * If the last event was a group event, it will have appended all
-	 * its siblings to the list, but we obtained 'tmp' before that which
-	 * will still point to the list head terminating the iteration.
-	 */
-	if (!list_empty(&child_ctx->pinned_groups) ||
-	    !list_empty(&child_ctx->flexible_groups))
-		goto again;
-
-	mutex_unlock(&child_ctx->mutex);
-
-	put_ctx(child_ctx);
-}
-
-static void perf_free_event(struct perf_event *event,
-			    struct perf_event_context *ctx)
-{
-	struct perf_event *parent = event->parent;
-
-	if (WARN_ON_ONCE(!parent))
-		return;
-
-	mutex_lock(&parent->child_mutex);
-	list_del_init(&event->child_list);
-	mutex_unlock(&parent->child_mutex);
-
-	fput(parent->filp);
-
-	perf_group_detach(event);
-	list_del_event(event, ctx);
-	free_event(event);
-}
-
-/*
- * free an unexposed, unused context as created by inheritance by
- * init_task below, used by fork() in case of fail.
- */
-void perf_event_free_task(struct task_struct *task)
-{
-	struct perf_event_context *ctx = task->perf_event_ctxp;
-	struct perf_event *event, *tmp;
-
-	if (!ctx)
-		return;
-
-	mutex_lock(&ctx->mutex);
-again:
-	list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
-		perf_free_event(event, ctx);
-
-	list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
-				 group_entry)
-		perf_free_event(event, ctx);
-
-	if (!list_empty(&ctx->pinned_groups) ||
-	    !list_empty(&ctx->flexible_groups))
-		goto again;
-
-	mutex_unlock(&ctx->mutex);
-
-	put_ctx(ctx);
-}
-
-static int
-inherit_task_group(struct perf_event *event, struct task_struct *parent,
-		   struct perf_event_context *parent_ctx,
-		   struct task_struct *child,
-		   int *inherited_all)
-{
-	int ret;
-	struct perf_event_context *child_ctx = child->perf_event_ctxp;
-
-	if (!event->attr.inherit) {
-		*inherited_all = 0;
-		return 0;
-	}
-
-	if (!child_ctx) {
-		/*
-		 * This is executed from the parent task context, so
-		 * inherit events that have been marked for cloning.
-		 * First allocate and initialize a context for the
-		 * child.
-		 */
-
-		child_ctx = kzalloc(sizeof(struct perf_event_context),
-				    GFP_KERNEL);
-		if (!child_ctx)
-			return -ENOMEM;
-
-		__perf_event_init_context(child_ctx, child);
-		child->perf_event_ctxp = child_ctx;
-		get_task_struct(child);
-	}
-
-	ret = inherit_group(event, parent, parent_ctx,
-			    child, child_ctx);
-
-	if (ret)
-		*inherited_all = 0;
-
-	return ret;
-}
-
-
-/*
- * Initialize the perf_event context in task_struct
- */
-int perf_event_init_task(struct task_struct *child)
-{
-	struct perf_event_context *child_ctx, *parent_ctx;
-	struct perf_event_context *cloned_ctx;
-	struct perf_event *event;
-	struct task_struct *parent = current;
-	int inherited_all = 1;
-	int ret = 0;
-
-	child->perf_event_ctxp = NULL;
-
-	mutex_init(&child->perf_event_mutex);
-	INIT_LIST_HEAD(&child->perf_event_list);
-
-	if (likely(!parent->perf_event_ctxp))
-		return 0;
-
-	/*
-	 * If the parent's context is a clone, pin it so it won't get
-	 * swapped under us.
-	 */
-	parent_ctx = perf_pin_task_context(parent);
-
-	/*
-	 * No need to check if parent_ctx != NULL here; since we saw
-	 * it non-NULL earlier, the only reason for it to become NULL
-	 * is if we exit, and since we're currently in the middle of
-	 * a fork we can't be exiting at the same time.
-	 */
-
-	/*
-	 * Lock the parent list. No need to lock the child - not PID
-	 * hashed yet and not running, so nobody can access it.
-	 */
-	mutex_lock(&parent_ctx->mutex);
-
-	/*
-	 * We dont have to disable NMIs - we are only looking at
-	 * the list, not manipulating it:
-	 */
-	list_for_each_entry(event, &parent_ctx->pinned_groups, group_entry) {
-		ret = inherit_task_group(event, parent, parent_ctx, child,
-					 &inherited_all);
-		if (ret)
-			break;
-	}
-
-	list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
-		ret = inherit_task_group(event, parent, parent_ctx, child,
-					 &inherited_all);
-		if (ret)
-			break;
-	}
-
-	child_ctx = child->perf_event_ctxp;
-
-	if (child_ctx && inherited_all) {
-		/*
-		 * Mark the child context as a clone of the parent
-		 * context, or of whatever the parent is a clone of.
-		 * Note that if the parent is a clone, it could get
-		 * uncloned at any point, but that doesn't matter
-		 * because the list of events and the generation
-		 * count can't have changed since we took the mutex.
-		 */
-		cloned_ctx = rcu_dereference(parent_ctx->parent_ctx);
-		if (cloned_ctx) {
-			child_ctx->parent_ctx = cloned_ctx;
-			child_ctx->parent_gen = parent_ctx->parent_gen;
-		} else {
-			child_ctx->parent_ctx = parent_ctx;
-			child_ctx->parent_gen = parent_ctx->generation;
-		}
-		get_ctx(child_ctx->parent_ctx);
-	}
-
-	mutex_unlock(&parent_ctx->mutex);
-
-	perf_unpin_context(parent_ctx);
-
-	return ret;
-}
-
-static void __init perf_event_init_all_cpus(void)
-{
-	int cpu;
-	struct perf_cpu_context *cpuctx;
-
-	for_each_possible_cpu(cpu) {
-		cpuctx = &per_cpu(perf_cpu_context, cpu);
-		mutex_init(&cpuctx->hlist_mutex);
-		__perf_event_init_context(&cpuctx->ctx, NULL);
-	}
-}
-
-static void __cpuinit perf_event_init_cpu(int cpu)
-{
-	struct perf_cpu_context *cpuctx;
-
-	cpuctx = &per_cpu(perf_cpu_context, cpu);
-
-	spin_lock(&perf_resource_lock);
-	cpuctx->max_pertask = perf_max_events - perf_reserved_percpu;
-	spin_unlock(&perf_resource_lock);
-
-	mutex_lock(&cpuctx->hlist_mutex);
-	if (cpuctx->hlist_refcount > 0) {
-		struct swevent_hlist *hlist;
-
-		hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
-		WARN_ON_ONCE(!hlist);
-		rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
-	}
-	mutex_unlock(&cpuctx->hlist_mutex);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
-static void __perf_event_exit_cpu(void *info)
-{
-	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
-	struct perf_event_context *ctx = &cpuctx->ctx;
-	struct perf_event *event, *tmp;
-
-	list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
-		__perf_event_remove_from_context(event);
-	list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
-		__perf_event_remove_from_context(event);
-}
-static void perf_event_exit_cpu(int cpu)
-{
-	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
-	struct perf_event_context *ctx = &cpuctx->ctx;
-
-	mutex_lock(&cpuctx->hlist_mutex);
-	swevent_hlist_release(cpuctx);
-	mutex_unlock(&cpuctx->hlist_mutex);
-
-	mutex_lock(&ctx->mutex);
-	smp_call_function_single(cpu, __perf_event_exit_cpu, NULL, 1);
-	mutex_unlock(&ctx->mutex);
-}
-#else
-static inline void perf_event_exit_cpu(int cpu) { }
-#endif
-
-static int __cpuinit
-perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
-{
-	unsigned int cpu = (long)hcpu;
-
-	switch (action & ~CPU_TASKS_FROZEN) {
-
-	case CPU_UP_PREPARE:
-	case CPU_DOWN_FAILED:
-		perf_event_init_cpu(cpu);
-		break;
-
-	case CPU_UP_CANCELED:
-	case CPU_DOWN_PREPARE:
-		perf_event_exit_cpu(cpu);
-		break;
-
-	default:
-		break;
-	}
-
-	return NOTIFY_OK;
-}
-
-/*
- * This has to have a higher priority than migration_notifier in sched.c.
- */
-static struct notifier_block __cpuinitdata perf_cpu_nb = {
-	.notifier_call		= perf_cpu_notify,
-	.priority		= 20,
-};
-
-void __init perf_event_init(void)
-{
-	perf_event_init_all_cpus();
-	perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
-			(void *)(long)smp_processor_id());
-	perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
-			(void *)(long)smp_processor_id());
-	register_cpu_notifier(&perf_cpu_nb);
-}
-
-static ssize_t perf_show_reserve_percpu(struct sysdev_class *class,
-					struct sysdev_class_attribute *attr,
-					char *buf)
-{
-	return sprintf(buf, "%d\n", perf_reserved_percpu);
-}
-
-static ssize_t
-perf_set_reserve_percpu(struct sysdev_class *class,
-			struct sysdev_class_attribute *attr,
-			const char *buf,
-			size_t count)
-{
-	struct perf_cpu_context *cpuctx;
-	unsigned long val;
-	int err, cpu, mpt;
-
-	err = strict_strtoul(buf, 10, &val);
-	if (err)
-		return err;
-	if (val > perf_max_events)
-		return -EINVAL;
-
-	spin_lock(&perf_resource_lock);
-	perf_reserved_percpu = val;
-	for_each_online_cpu(cpu) {
-		cpuctx = &per_cpu(perf_cpu_context, cpu);
-		raw_spin_lock_irq(&cpuctx->ctx.lock);
-		mpt = min(perf_max_events - cpuctx->ctx.nr_events,
-			  perf_max_events - perf_reserved_percpu);
-		cpuctx->max_pertask = mpt;
-		raw_spin_unlock_irq(&cpuctx->ctx.lock);
-	}
-	spin_unlock(&perf_resource_lock);
-
-	return count;
-}
-
-static ssize_t perf_show_overcommit(struct sysdev_class *class,
-				    struct sysdev_class_attribute *attr,
-				    char *buf)
-{
-	return sprintf(buf, "%d\n", perf_overcommit);
-}
-
-static ssize_t
-perf_set_overcommit(struct sysdev_class *class,
-		    struct sysdev_class_attribute *attr,
-		    const char *buf, size_t count)
-{
-	unsigned long val;
-	int err;
-
-	err = strict_strtoul(buf, 10, &val);
-	if (err)
-		return err;
-	if (val > 1)
-		return -EINVAL;
-
-	spin_lock(&perf_resource_lock);
-	perf_overcommit = val;
-	spin_unlock(&perf_resource_lock);
-
-	return count;
-}
-
-static SYSDEV_CLASS_ATTR(
-				reserve_percpu,
-				0644,
-				perf_show_reserve_percpu,
-				perf_set_reserve_percpu
-			);
-
-static SYSDEV_CLASS_ATTR(
-				overcommit,
-				0644,
-				perf_show_overcommit,
-				perf_set_overcommit
-			);
-
-static struct attribute *perfclass_attrs[] = {
-	&attr_reserve_percpu.attr,
-	&attr_overcommit.attr,
-	NULL
-};
-
-static struct attribute_group perfclass_attr_group = {
-	.attrs			= perfclass_attrs,
-	.name			= "perf_events",
-};
-
-static int __init perf_event_sysfs_init(void)
-{
-	return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
-				  &perfclass_attr_group);
-}
-device_initcall(perf_event_sysfs_init);
-- 
1.7.3.1

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