Re: [PATCH] LoongArch: Add perf events support
From: Qi Hu
Date: Tue Aug 16 2022 - 06:49:11 EST
On 2022/8/16 16:18, Huacai Chen wrote:
Hi, Xuerui,
On Tue, Aug 16, 2022 at 1:46 PM WANG Xuerui <kernel@xxxxxxxxxx> wrote:
On 2022/8/15 20:47, Huacai Chen wrote:
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
arch/loongarch/Kconfig | 2 +
arch/loongarch/include/uapi/asm/perf_regs.h | 40 +
arch/loongarch/kernel/Makefile | 2 +
arch/loongarch/kernel/perf_event.c | 909 ++++++++++++++++++++
arch/loongarch/kernel/perf_regs.c | 50 ++
5 files changed, 1003 insertions(+)
create mode 100644 arch/loongarch/include/uapi/asm/perf_regs.h
create mode 100644 arch/loongarch/kernel/perf_event.c
create mode 100644 arch/loongarch/kernel/perf_regs.c
The code seems mostly ripped from arch/mips/kernel/perf_event_mipsxx.c.
I reviewed about half of the code then suddenly realized I might be
looking at MIPS code, given some of the English strings there seemed way
too "natural"...
But unfortunately, at least for 3A5000 whose micro-architecture is
largely shared with the MIPS-implementing 3A4000, it seems inevitable to
involve some of the more MIPS-looking logic. The 1st-generation LA
privileged architecture is way too much MIPS-like after all, so if we
want any support for the 3A5000 we'd have to include this.
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 24665808cf3d..9478f9646fa5 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -93,6 +93,8 @@ config LOONGARCH
select HAVE_NMI
select HAVE_PCI
select HAVE_PERF_EVENTS
+ select HAVE_PERF_REGS
+ select HAVE_PERF_USER_STACK_DUMP
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RSEQ
select HAVE_SETUP_PER_CPU_AREA if NUMA
diff --git a/arch/loongarch/include/uapi/asm/perf_regs.h b/arch/loongarch/include/uapi/asm/perf_regs.h
new file mode 100644
index 000000000000..9943d418e01d
--- /dev/null
+++ b/arch/loongarch/include/uapi/asm/perf_regs.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_LOONGARCH_PERF_REGS_H
+#define _ASM_LOONGARCH_PERF_REGS_H
+
+enum perf_event_loongarch_regs {
+ PERF_REG_LOONGARCH_PC,
+ PERF_REG_LOONGARCH_R1,
+ PERF_REG_LOONGARCH_R2,
+ PERF_REG_LOONGARCH_R3,
+ PERF_REG_LOONGARCH_R4,
+ PERF_REG_LOONGARCH_R5,
+ PERF_REG_LOONGARCH_R6,
+ PERF_REG_LOONGARCH_R7,
+ PERF_REG_LOONGARCH_R8,
+ PERF_REG_LOONGARCH_R9,
+ PERF_REG_LOONGARCH_R10,
+ PERF_REG_LOONGARCH_R11,
+ PERF_REG_LOONGARCH_R12,
+ PERF_REG_LOONGARCH_R13,
+ PERF_REG_LOONGARCH_R14,
+ PERF_REG_LOONGARCH_R15,
+ PERF_REG_LOONGARCH_R16,
+ PERF_REG_LOONGARCH_R17,
+ PERF_REG_LOONGARCH_R18,
+ PERF_REG_LOONGARCH_R19,
+ PERF_REG_LOONGARCH_R20,
+ PERF_REG_LOONGARCH_R21,
+ PERF_REG_LOONGARCH_R22,
+ PERF_REG_LOONGARCH_R23,
+ PERF_REG_LOONGARCH_R24,
+ PERF_REG_LOONGARCH_R25,
+ PERF_REG_LOONGARCH_R26,
+ PERF_REG_LOONGARCH_R27,
+ PERF_REG_LOONGARCH_R28,
+ PERF_REG_LOONGARCH_R29,
+ PERF_REG_LOONGARCH_R30,
+ PERF_REG_LOONGARCH_R31,
+ PERF_REG_LOONGARCH_MAX = PERF_REG_LOONGARCH_R31 + 1,
No need for this "PERF_REG_LOONGARCH_R31 + 1" because it's what happens
without the assignment anyway?
PERF_REG_LOONGARCH_MAX is used in perf_events.c
I think Xuerui wants to say "PERF_REG_LOONGARCH_MAX" is enough, and "=
PERF_REG_LOONGARCH_R31 + 1" can be removed.
Qi
+};
+#endif /* _ASM_LOONGARCH_PERF_REGS_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index e5be17009fe8..a213e994db68 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -26,4 +26,6 @@ obj-$(CONFIG_NUMA) += numa.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
+obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
+
CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
diff --git a/arch/loongarch/kernel/perf_event.c b/arch/loongarch/kernel/perf_event.c
new file mode 100644
index 000000000000..00cdbcebaf80
--- /dev/null
+++ b/arch/loongarch/kernel/perf_event.c
@@ -0,0 +1,909 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Linux performance counter support for LoongArch.
Please indicate its MIPS origin and copyright info ;-)
OK, thanks.
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/uaccess.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/irq.h>
+#include <asm/irq_regs.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static unsigned long
+user_backtrace(struct perf_callchain_entry_ctx *entry, unsigned long fp)
+{
+ struct stack_frame buftail;
+ unsigned long err;
+ unsigned long __user *user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
+
+ /* Also check accessibility of one struct frame_tail beyond */
+ if (!access_ok(user_frame_tail, sizeof(buftail)))
+ return 0;
+
+ pagefault_disable();
+ err = __copy_from_user_inatomic(&buftail, user_frame_tail, sizeof(buftail));
+ pagefault_enable();
+
+ if (err || (unsigned long)user_frame_tail >= buftail.fp)
+ return 0;
+
+ perf_callchain_store(entry, buftail.ra);
+
+ return buftail.fp;
+}
+
+void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
+ struct pt_regs *regs)
+{
+ unsigned long fp;
+
+ if (perf_guest_state()) {
+ /* We don't support guest os callchain now */
+ return;
+ }
+
+ perf_callchain_store(entry, regs->csr_era);
+
+ fp = regs->regs[22];
+
+ while (entry->nr < entry->max_stack && fp && !((unsigned long)fp & 0xf))
+ fp = user_backtrace(entry, fp);
+}
+
+void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
+ struct pt_regs *regs)
+{
+ struct unwind_state state;
+ unsigned long addr;
+
+ for (unwind_start(&state, current, regs);
+ !unwind_done(&state); unwind_next_frame(&state)) {
+ addr = unwind_get_return_address(&state);
+ if (!addr || perf_callchain_store(entry, addr))
+ return;
+ }
+}
+
+#define LOONGARCH_MAX_HWEVENTS 4
+
+struct cpu_hw_events {
+ /* Array of events on this cpu. */
+ struct perf_event *events[LOONGARCH_MAX_HWEVENTS];
+
+ /*
+ * Set the bit (indexed by the counter number) when the counter
+ * is used for an event.
+ */
+ unsigned long used_mask[BITS_TO_LONGS(LOONGARCH_MAX_HWEVENTS)];
+
+ /*
+ * Software copy of the control register for each performance counter.
+ * LoongArch CPUs vary in performance counters. They use this differently,
+ * and even may not use it.
I can't easily make sense of the paragraph. "Software copy" could mean
"Saved copy", but how do "use differently" and "even may not use it"
mean? For the latter I can't deduce if it's originally "some even may
not exist" in someone's head, and for the former I can't imagine what's
the possible cases and why we would care.
Maybe explain a little bit more?
I think we should remove those useless lines.
+ */
+ unsigned int saved_ctrl[LOONGARCH_MAX_HWEVENTS];
+};
+static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
+ .saved_ctrl = {0},
+};
+
+/* The description of LoongArch performance events. */
+struct loongarch_perf_event {
+ unsigned int event_id;
+};
+
+static struct loongarch_perf_event raw_event;
+static DEFINE_MUTEX(raw_event_mutex);
+
+#define C(x) PERF_COUNT_HW_CACHE_##x
+#define HW_OP_UNSUPPORTED 0xffffffff
+#define CACHE_OP_UNSUPPORTED 0xffffffff
+
+#define PERF_MAP_ALL_UNSUPPORTED \
+ [0 ... PERF_COUNT_HW_MAX - 1] = {HW_OP_UNSUPPORTED}
+
+#define PERF_CACHE_MAP_ALL_UNSUPPORTED \
+[0 ... C(MAX) - 1] = { \
+ [0 ... C(OP_MAX) - 1] = { \
+ [0 ... C(RESULT_MAX) - 1] = {CACHE_OP_UNSUPPORTED}, \
+ }, \
+}
+
+struct loongarch_pmu {
+ u64 max_period;
+ u64 valid_count;
+ u64 overflow;
+ const char *name;
+ u64 (*read_counter)(unsigned int idx);
+ void (*write_counter)(unsigned int idx, u64 val);
+ const struct loongarch_perf_event *(*map_raw_event)(u64 config);
+ const struct loongarch_perf_event (*general_event_map)[PERF_COUNT_HW_MAX];
+ const struct loongarch_perf_event (*cache_event_map)
+ [PERF_COUNT_HW_CACHE_MAX]
+ [PERF_COUNT_HW_CACHE_OP_MAX]
+ [PERF_COUNT_HW_CACHE_RESULT_MAX];
Apparently general_event_map and cache_event_map are not function
pointers? So the parens around the field name should be removed.
They are not function pointers, but "array pointers", but we shouldn't
change them to "array to pointers"..
+ unsigned int num_counters;
+};
+
+static struct loongarch_pmu loongarch_pmu;
+
+#define M_PERFCTL_EVENT(event) (event & CSR_PERFCTRL_EVENT)
+
+#define M_PERFCTL_COUNT_EVENT_WHENEVER (CSR_PERFCTRL_PLV0 | \
+ CSR_PERFCTRL_PLV1 | \
+ CSR_PERFCTRL_PLV2 | \
+ CSR_PERFCTRL_PLV3 | \
+ CSR_PERFCTRL_IE)
+
+#define M_PERFCTL_CONFIG_MASK 0x1f0000
+
+#define CNTR_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
Isn't this just GENMASK(n - 1, 0)?
Yes, you are right.
+
+static void resume_local_counters(void);
+static void pause_local_counters(void);
+
+static u64 loongarch_pmu_read_counter(unsigned int idx)
+{
+ u64 val = -1;
+
+ switch (idx) {
+ case 0:
+ val = read_csr_perfcntr0();
+ break;
+ case 1:
+ val = read_csr_perfcntr1();
+ break;
+ case 2:
+ val = read_csr_perfcntr2();
+ break;
+ case 3:
+ val = read_csr_perfcntr3();
+ break;
+ default:
+ WARN_ONCE(1, "Invalid performance counter number (%d)\n", idx);
+ return 0;
+ }
+
+ return val;
+}
+
+static void loongarch_pmu_write_counter(unsigned int idx, u64 val)
+{
+ switch (idx) {
+ case 0:
+ write_csr_perfcntr0(val);
+ return;
+ case 1:
+ write_csr_perfcntr1(val);
+ return;
+ case 2:
+ write_csr_perfcntr2(val);
+ return;
+ case 3:
+ write_csr_perfcntr3(val);
+ return;
Want a default branch for this function, similar to the read case?
Yes, that is needed.
+ }
+}
+
+static unsigned int loongarch_pmu_read_control(unsigned int idx)
+{
+ unsigned int val = -1;
+
+ switch (idx) {
+ case 0:
+ val = read_csr_perfctrl0();
+ break;
+ case 1:
+ val = read_csr_perfctrl1();
+ break;
+ case 2:
+ val = read_csr_perfctrl2();
+ break;
+ case 3:
+ val = read_csr_perfctrl3();
+ break;
+ default:
+ WARN_ONCE(1, "Invalid performance counter number (%d)\n", idx);
+ return 0;
+ }
+
+ return val;
+}
+
+static void loongarch_pmu_write_control(unsigned int idx, unsigned int val)
+{
+ switch (idx) {
+ case 0:
+ write_csr_perfctrl0(val);
+ return;
+ case 1:
+ write_csr_perfctrl1(val);
+ return;
+ case 2:
+ write_csr_perfctrl2(val);
+ return;
+ case 3:
+ write_csr_perfctrl3(val);
+ return;
Similarly here.
+ }
+}
+
+static int loongarch_pmu_alloc_counter(struct cpu_hw_events *cpuc,
+ struct hw_perf_event *hwc)
+{
+ int i;
+
+ for (i = loongarch_pmu.num_counters - 1; i >= 0; i--) {
+ if (!test_and_set_bit(i, cpuc->used_mask))
+ return i;
+ }
+
+ return -EAGAIN;
+}
+
+static void loongarch_pmu_enable_event(struct hw_perf_event *evt, int idx)
+{
+ struct perf_event *event = container_of(evt, struct perf_event, hw);
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ unsigned int cpu;
+
+ WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
+
+ cpuc->saved_ctrl[idx] = M_PERFCTL_EVENT(evt->event_base & 0xff) |
+ (evt->config_base & M_PERFCTL_CONFIG_MASK) |
+ /* Make sure interrupt enabled. */
+ CSR_PERFCTRL_IE;
+
+ cpu = (event->cpu >= 0) ? event->cpu : smp_processor_id();
+
+ pr_debug("Enabling perf counter for CPU%d\n", cpu);
+ /*
+ * We do not actually let the counter run. Leave it until start().
+ */
+}
+
+static void loongarch_pmu_disable_event(int idx)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ unsigned long flags;
+
+ WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
+
+ local_irq_save(flags);
+ cpuc->saved_ctrl[idx] = loongarch_pmu_read_control(idx) &
+ ~M_PERFCTL_COUNT_EVENT_WHENEVER;
+ loongarch_pmu_write_control(idx, cpuc->saved_ctrl[idx]);
+ local_irq_restore(flags);
+}
+
+static int loongarch_pmu_event_set_period(struct perf_event *event,
+ struct hw_perf_event *hwc,
+ int idx)
+{
+ u64 left = local64_read(&hwc->period_left);
+ u64 period = hwc->sample_period;
+ int ret = 0;
+
+ if (unlikely((left + period) & (1ULL << 63))) {
+ /* left underflowed by more than period. */
+ left = period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ ret = 1;
+ } else if (unlikely((left + period) <= period)) {
+ /* left underflowed by less than period. */
+ left += period;
+ local64_set(&hwc->period_left, left);
+ hwc->last_period = period;
+ ret = 1;
+ }
+
+ if (left > loongarch_pmu.max_period) {
+ left = loongarch_pmu.max_period;
+ local64_set(&hwc->period_left, left);
+ }
+
+ local64_set(&hwc->prev_count, loongarch_pmu.overflow - left);
+
+ loongarch_pmu.write_counter(idx, loongarch_pmu.overflow - left);
+
+ perf_event_update_userpage(event);
+
+ return ret;
+}
+
+static void loongarch_pmu_event_update(struct perf_event *event,
+ struct hw_perf_event *hwc,
+ int idx)
+{
+ u64 delta;
+ u64 prev_raw_count, new_raw_count;
+
+again:
+ prev_raw_count = local64_read(&hwc->prev_count);
+ new_raw_count = loongarch_pmu.read_counter(idx);
+
+ if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+ new_raw_count) != prev_raw_count)
+ goto again;
+
+ delta = new_raw_count - prev_raw_count;
+
+ local64_add(delta, &event->count);
+ local64_sub(delta, &hwc->period_left);
+}
+
+static void loongarch_pmu_start(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (flags & PERF_EF_RELOAD)
+ WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
+
+ hwc->state = 0;
+
+ /* Set the period for the event. */
+ loongarch_pmu_event_set_period(event, hwc, hwc->idx);
+
+ /* Enable the event. */
+ loongarch_pmu_enable_event(hwc, hwc->idx);
+}
+
+static void loongarch_pmu_stop(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (!(hwc->state & PERF_HES_STOPPED)) {
+ /* We are working on a local event. */
+ loongarch_pmu_disable_event(hwc->idx);
+ barrier();
+ loongarch_pmu_event_update(event, hwc, hwc->idx);
+ hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+ }
+}
+
+static int loongarch_pmu_add(struct perf_event *event, int flags)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx;
+ int err = 0;
+
+ perf_pmu_disable(event->pmu);
+
+ /* To look for a free counter for this event. */
+ idx = loongarch_pmu_alloc_counter(cpuc, hwc);
+ if (idx < 0) {
+ err = idx;
+ goto out;
+ }
+
+ /*
+ * If there is an event in the counter we are going to use then
+ * make sure it is disabled.
+ */
+ event->hw.idx = idx;
+ loongarch_pmu_disable_event(idx);
+ cpuc->events[idx] = event;
+
+ hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+ if (flags & PERF_EF_START)
+ loongarch_pmu_start(event, PERF_EF_RELOAD);
+
+ /* Propagate our changes to the userspace mapping. */
+ perf_event_update_userpage(event);
+
+out:
+ perf_pmu_enable(event->pmu);
+ return err;
+}
+
+static void loongarch_pmu_del(struct perf_event *event, int flags)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx = hwc->idx;
+
+ WARN_ON(idx < 0 || idx >= loongarch_pmu.num_counters);
+
+ loongarch_pmu_stop(event, PERF_EF_UPDATE);
+ cpuc->events[idx] = NULL;
+ clear_bit(idx, cpuc->used_mask);
+
+ perf_event_update_userpage(event);
+}
+
+static void loongarch_pmu_read(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ /* Don't read disabled counters! */
+ if (hwc->idx < 0)
+ return;
+
+ loongarch_pmu_event_update(event, hwc, hwc->idx);
+}
+
+static void loongarch_pmu_enable(struct pmu *pmu)
+{
+ resume_local_counters();
+}
+
+static void loongarch_pmu_disable(struct pmu *pmu)
+{
+ pause_local_counters();
+}
+
+static atomic_t active_events = ATOMIC_INIT(0);
+static DEFINE_MUTEX(pmu_reserve_mutex);
+
+static void reset_counters(void *arg);
+static int __hw_perf_event_init(struct perf_event *event);
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+ if (atomic_dec_and_mutex_lock(&active_events,
+ &pmu_reserve_mutex)) {
+ /*
+ * We must not call the destroy function with interrupts
+ * disabled.
+ */
+ on_each_cpu(reset_counters,
+ (void *)(long)loongarch_pmu.num_counters, 1);
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+}
+
+/* This is needed by specific irq handlers in perf_event_*.c */
+static void handle_associated_event(struct cpu_hw_events *cpuc,
+ int idx, struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ struct perf_event *event = cpuc->events[idx];
+ struct hw_perf_event *hwc = &event->hw;
+
+ loongarch_pmu_event_update(event, hwc, idx);
+ data->period = event->hw.last_period;
+ if (!loongarch_pmu_event_set_period(event, hwc, idx))
+ return;
+
+ if (perf_event_overflow(event, data, regs))
+ loongarch_pmu_disable_event(idx);
+}
+
+static irqreturn_t pmu_handle_irq(int irq, void *dev)
+{
+ int handled = IRQ_NONE;
+ unsigned int counters = loongarch_pmu.num_counters;
+ u64 counter;
+ struct pt_regs *regs;
+ struct perf_sample_data data;
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+ /*
+ * First we pause the local counters, so that when we are locked
+ * here, the counters are all paused. When it gets locked due to
+ * perf_disable(), the timer interrupt handler will be delayed.
+ *
+ * See also loongarch_pmu_start().
+ */
+ pause_local_counters();
+
+ regs = get_irq_regs();
+
+ perf_sample_data_init(&data, 0, 0);
+
+ switch (counters) {
+#define HANDLE_COUNTER(n) \
+ case n + 1: \
+ if (test_bit(n, cpuc->used_mask)) { \
+ counter = loongarch_pmu.read_counter(n); \
+ if (counter & loongarch_pmu.overflow) { \
+ handle_associated_event(cpuc, n, &data, regs); \
+ handled = IRQ_HANDLED; \
+ } \
+ }
+ HANDLE_COUNTER(3)
+ fallthrough;
+ HANDLE_COUNTER(2)
+ fallthrough;
+ HANDLE_COUNTER(1)
+ fallthrough;
+ HANDLE_COUNTER(0)
+ }
+
+ resume_local_counters();
+
+ /*
+ * Do all the work for the pending perf events. We can do this
+ * in here because the performance counter interrupt is a regular
+ * interrupt, not NMI.
+ */
+ if (handled == IRQ_HANDLED)
+ irq_work_run();
+
+ return handled;
+}
+
+static int get_pmc_irq(void)
+{
+ struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
+
+ if (d)
+ return irq_create_mapping(d, EXCCODE_PMC - EXCCODE_INT_START);
+
+ return -EINVAL;
+}
+
+static int loongarch_pmu_event_init(struct perf_event *event)
+{
+ int r, irq;
+ unsigned long flags;
+
+ /* does not support taken branch sampling */
+ if (has_branch_stack(event))
+ return -EOPNOTSUPP;
+
+ switch (event->attr.type) {
+ case PERF_TYPE_RAW:
+ case PERF_TYPE_HARDWARE:
+ case PERF_TYPE_HW_CACHE:
+ break;
+
+ default:
+ /* Init it to avoid false validate_group */
+ event->hw.event_base = 0xffffffff;
+ return -ENOENT;
+ }
+
+ if (event->cpu >= 0 && !cpu_online(event->cpu))
+ return -ENODEV;
+
+ irq = get_pmc_irq();
+ flags = IRQF_PERCPU | IRQF_NOBALANCING | IRQF_NO_THREAD | IRQF_NO_SUSPEND | IRQF_SHARED;
+ if (!atomic_inc_not_zero(&active_events)) {
+ mutex_lock(&pmu_reserve_mutex);
+ if (atomic_read(&active_events) == 0) {
+ r = request_irq(irq, pmu_handle_irq,
+ flags, "Perf_PMU", &loongarch_pmu);
+ if (r < 0) {
+ pr_warn("PMU IRQ request failed\n");
+ return -ENODEV;
+ }
+ }
+ atomic_inc(&active_events);
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+
+ return __hw_perf_event_init(event);
+}
+
+static struct pmu pmu = {
+ .pmu_enable = loongarch_pmu_enable,
+ .pmu_disable = loongarch_pmu_disable,
+ .event_init = loongarch_pmu_event_init,
+ .add = loongarch_pmu_add,
+ .del = loongarch_pmu_del,
+ .start = loongarch_pmu_start,
+ .stop = loongarch_pmu_stop,
+ .read = loongarch_pmu_read,
+};
+
+static unsigned int loongarch_pmu_perf_event_encode(const struct loongarch_perf_event *pev)
+{
+ return (pev->event_id & 0xff);
+}
+
+static const struct loongarch_perf_event *loongarch_pmu_map_general_event(int idx)
+{
+ const struct loongarch_perf_event *pev;
+
+ pev = &(*loongarch_pmu.general_event_map)[idx];
+
+ if (pev->event_id == HW_OP_UNSUPPORTED)
+ return ERR_PTR(-ENOENT);
+
+ return pev;
+}
+
+static const struct loongarch_perf_event *loongarch_pmu_map_cache_event(u64 config)
+{
+ unsigned int cache_type, cache_op, cache_result;
+ const struct loongarch_perf_event *pev;
+
+ cache_type = (config >> 0) & 0xff;
+ if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+ return ERR_PTR(-EINVAL);
+
+ cache_op = (config >> 8) & 0xff;
+ if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
+ return ERR_PTR(-EINVAL);
+
+ cache_result = (config >> 16) & 0xff;
+ if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+ return ERR_PTR(-EINVAL);
+
+ pev = &((*loongarch_pmu.cache_event_map)
+ [cache_type]
+ [cache_op]
+ [cache_result]);
+
+ if (pev->event_id == CACHE_OP_UNSUPPORTED)
+ return ERR_PTR(-ENOENT);
+
+ return pev;
+}
+
+static int validate_group(struct perf_event *event)
+{
+ struct perf_event *sibling, *leader = event->group_leader;
+ struct cpu_hw_events fake_cpuc;
+
+ memset(&fake_cpuc, 0, sizeof(fake_cpuc));
+
+ if (loongarch_pmu_alloc_counter(&fake_cpuc, &leader->hw) < 0)
+ return -EINVAL;
+
+ for_each_sibling_event(sibling, leader) {
+ if (loongarch_pmu_alloc_counter(&fake_cpuc, &sibling->hw) < 0)
+ return -EINVAL;
+ }
+
+ if (loongarch_pmu_alloc_counter(&fake_cpuc, &event->hw) < 0)
+ return -EINVAL;
+
+ return 0;
+}
+
+static void reset_counters(void *arg)
+{
+ int counters = (int)(long)arg;
+
+ switch (counters) {
+ case 4:
+ loongarch_pmu_write_control(3, 0);
+ loongarch_pmu.write_counter(3, 0);
+ fallthrough;
+ case 3:
+ loongarch_pmu_write_control(2, 0);
+ loongarch_pmu.write_counter(2, 0);
+ fallthrough;
+ case 2:
+ loongarch_pmu_write_control(1, 0);
+ loongarch_pmu.write_counter(1, 0);
+ fallthrough;
+ case 1:
+ loongarch_pmu_write_control(0, 0);
+ loongarch_pmu.write_counter(0, 0);
+ }
+}
+
+static const struct loongarch_perf_event loongson_new_event_map[PERF_COUNT_HW_MAX] = {
+ PERF_MAP_ALL_UNSUPPORTED,
+ [PERF_COUNT_HW_CPU_CYCLES] = { 0x00 },
+ [PERF_COUNT_HW_INSTRUCTIONS] = { 0x01 },
+ [PERF_COUNT_HW_CACHE_REFERENCES] = { 0x08 },
+ [PERF_COUNT_HW_CACHE_MISSES] = { 0x09 },
+ [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = { 0x02 },
+ [PERF_COUNT_HW_BRANCH_MISSES] = { 0x03 },
+};
+
+static const struct loongarch_perf_event loongson_new_cache_map
+ [PERF_COUNT_HW_CACHE_MAX]
+ [PERF_COUNT_HW_CACHE_OP_MAX]
+ [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+PERF_CACHE_MAP_ALL_UNSUPPORTED,
+[C(L1D)] = {
+ /*
+ * Like some other architectures (e.g. ARM), the performance
+ * counters don't differentiate between read and write
+ * accesses/misses, so this isn't strictly correct, but it's the
+ * best we can do. Writes and reads get combined.
+ */
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = { 0x8 },
+ [C(RESULT_MISS)] = { 0x9 },
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = { 0x8 },
+ [C(RESULT_MISS)] = { 0x9 },
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = { 0xaa },
+ [C(RESULT_MISS)] = { 0xa9 },
+ },
+},
+[C(L1I)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = { 0x6 },
+ [C(RESULT_MISS)] = { 0x7 },
+ },
+},
+[C(LL)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = { 0xc },
+ [C(RESULT_MISS)] = { 0xd },
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = { 0xc },
+ [C(RESULT_MISS)] = { 0xd },
+ },
+},
+[C(ITLB)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_MISS)] = { 0x3b },
+ },
+},
+[C(DTLB)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = { 0x4 },
+ [C(RESULT_MISS)] = { 0x3c },
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = { 0x4 },
+ [C(RESULT_MISS)] = { 0x3c },
+ },
+},
+[C(BPU)] = {
+ /* Using the same code for *HW_BRANCH* */
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = { 0x02 },
+ [C(RESULT_MISS)] = { 0x03 },
+ },
+},
+};
+
+static int __hw_perf_event_init(struct perf_event *event)
+{
+ struct perf_event_attr *attr = &event->attr;
+ struct hw_perf_event *hwc = &event->hw;
+ const struct loongarch_perf_event *pev;
+ int err;
+
+ /* Returning LoongArch event descriptor for generic perf event. */
+ if (PERF_TYPE_HARDWARE == event->attr.type) {
+ if (event->attr.config >= PERF_COUNT_HW_MAX)
+ return -EINVAL;
+ pev = loongarch_pmu_map_general_event(event->attr.config);
+ } else if (PERF_TYPE_HW_CACHE == event->attr.type) {
+ pev = loongarch_pmu_map_cache_event(event->attr.config);
+ } else if (PERF_TYPE_RAW == event->attr.type) {
+ /* We are working on the global raw event. */
+ mutex_lock(&raw_event_mutex);
+ pev = loongarch_pmu.map_raw_event(event->attr.config);
+ } else {
+ /* The event type is not (yet) supported. */
+ return -EOPNOTSUPP;
+ }
+
+ if (IS_ERR(pev)) {
+ if (PERF_TYPE_RAW == event->attr.type)
+ mutex_unlock(&raw_event_mutex);
+ return PTR_ERR(pev);
+ }
+
+ /*
+ * We allow max flexibility on how each individual counter shared
+ * by the single CPU operates (the mode exclusion and the range).
+ */
+ hwc->config_base = CSR_PERFCTRL_IE;
+
+ hwc->event_base = loongarch_pmu_perf_event_encode(pev);
+ if (PERF_TYPE_RAW == event->attr.type)
+ mutex_unlock(&raw_event_mutex);
+
+ if (!attr->exclude_user) {
+ hwc->config_base |= CSR_PERFCTRL_PLV3;
+ hwc->config_base |= CSR_PERFCTRL_PLV2;
+ }
+ if (!attr->exclude_kernel) {
+ hwc->config_base |= CSR_PERFCTRL_PLV0;
+ }
+ if (!attr->exclude_hv) {
+ hwc->config_base |= CSR_PERFCTRL_PLV1;
+ }
+
+ hwc->config_base &= M_PERFCTL_CONFIG_MASK;
+ /*
+ * The event can belong to another cpu. We do not assign a local
+ * counter for it for now.
+ */
+ hwc->idx = -1;
+ hwc->config = 0;
+
+ if (!hwc->sample_period) {
+ hwc->sample_period = loongarch_pmu.max_period;
+ hwc->last_period = hwc->sample_period;
+ local64_set(&hwc->period_left, hwc->sample_period);
+ }
+
+ err = 0;
+ if (event->group_leader != event)
+ err = validate_group(event);
+
+ event->destroy = hw_perf_event_destroy;
+
+ if (err)
+ event->destroy(event);
+
+ return err;
+}
+
+static void pause_local_counters(void)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ int ctr = loongarch_pmu.num_counters;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ do {
+ ctr--;
+ cpuc->saved_ctrl[ctr] = loongarch_pmu_read_control(ctr);
+ loongarch_pmu_write_control(ctr, cpuc->saved_ctrl[ctr] &
+ ~M_PERFCTL_COUNT_EVENT_WHENEVER);
+ } while (ctr > 0);
+ local_irq_restore(flags);
+}
+
+static void resume_local_counters(void)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ int ctr = loongarch_pmu.num_counters;
+
+ do {
+ ctr--;
+ loongarch_pmu_write_control(ctr, cpuc->saved_ctrl[ctr]);
+ } while (ctr > 0);
+}
+
+static const struct loongarch_perf_event *loongarch_pmu_map_raw_event(u64 config)
+{
+ raw_event.event_id = config & 0xff;
+
+ return &raw_event;
+}
+
+static int __init
+init_hw_perf_events(void)
+{
+ int counters = 4;
+
+ if (!cpu_has_pmp)
+ return -ENODEV;
+
+ pr_info("Performance counters: ");
+
+ loongarch_pmu.num_counters = counters;
+ loongarch_pmu.max_period = (1ULL << 63) - 1;
+ loongarch_pmu.valid_count = (1ULL << 63) - 1;
+ loongarch_pmu.overflow = 1ULL << 63;
+ loongarch_pmu.name = "loongarch/loongson64";
+ loongarch_pmu.read_counter = loongarch_pmu_read_counter;
+ loongarch_pmu.write_counter = loongarch_pmu_write_counter;
+ loongarch_pmu.map_raw_event = loongarch_pmu_map_raw_event;
+ loongarch_pmu.general_event_map = &loongson_new_event_map;
+ loongarch_pmu.cache_event_map = &loongson_new_cache_map;
+
+ on_each_cpu(reset_counters, (void *)(long)counters, 1);
+
+ pr_cont("%s PMU enabled, %d %d-bit counters available to each "
+ "CPU.\n", loongarch_pmu.name, counters, 64);
+
+ perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
+
+ return 0;
+}
+early_initcall(init_hw_perf_events);
diff --git a/arch/loongarch/kernel/perf_regs.c b/arch/loongarch/kernel/perf_regs.c
new file mode 100644
index 000000000000..a5e9768e8414
--- /dev/null
+++ b/arch/loongarch/kernel/perf_regs.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
And this file.
OK, thanks.
Huacai
+ */
+
+#include <linux/perf_event.h>
+
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_32BIT
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+ return PERF_SAMPLE_REGS_ABI_32;
+}
+#else /* Must be CONFIG_64BIT */
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+ if (test_tsk_thread_flag(tsk, TIF_32BIT_REGS))
+ return PERF_SAMPLE_REGS_ABI_32;
+ else
+ return PERF_SAMPLE_REGS_ABI_64;
+}
+#endif /* CONFIG_32BIT */
+
+int perf_reg_validate(u64 mask)
+{
+ if (!mask)
+ return -EINVAL;
+ if (mask & ~((1ull << PERF_REG_LOONGARCH_MAX) - 1))
+ return -EINVAL;
+ return 0;
+}
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+ if (WARN_ON_ONCE((u32)idx >= PERF_REG_LOONGARCH_MAX))
+ return 0;
+
+ if ((u32)idx == PERF_REG_LOONGARCH_PC)
+ return regs->csr_era;
+
+ return regs->regs[idx];
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
--
WANG "xen0n" Xuerui
Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/