x86: split spinlock implementations out into their own files
From: Jeremy Fitzhardinge
Date: Wed Jul 23 2008 - 16:29:28 EST
ftrace requires certain low-level code, like spinlocks and timestamps,
to be compiled without -pg in order to avoid infinite recursion. This
patch splits out the core paravirt spinlocks and the Xen spinlocks
into separate files which can be compiled without -pg.
Also do xen/time.c while we're about it. As a result, we can now use
ftrace within a Xen domain.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
arch/x86/kernel/Makefile | 4
arch/x86/kernel/paravirt-spinlocks.c | 31 +++++
arch/x86/kernel/paravirt.c | 23 ----
arch/x86/xen/Makefile | 8 +
arch/x86/xen/smp.c | 167 -------------------------------
arch/x86/xen/spinlock.c | 183 ++++++++++++++++++++++++++++++++++
arch/x86/xen/xen-ops.h | 3
7 files changed, 226 insertions(+), 193 deletions(-)
===================================================================
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -10,7 +10,7 @@
# Do not profile debug and lowlevel utilities
CFLAGS_REMOVE_tsc.o = -pg
CFLAGS_REMOVE_rtc.o = -pg
-CFLAGS_REMOVE_paravirt.o = -pg
+CFLAGS_REMOVE_paravirt-spinlocks.o = -pg
endif
#
@@ -90,7 +90,7 @@
obj-$(CONFIG_VMI) += vmi_32.o vmiclock_32.o
obj-$(CONFIG_KVM_GUEST) += kvm.o
obj-$(CONFIG_KVM_CLOCK) += kvmclock.o
-obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o
+obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o paravirt-spinlocks.o
obj-$(CONFIG_PARAVIRT_CLOCK) += pvclock.o
obj-$(CONFIG_PCSPKR_PLATFORM) += pcspeaker.o
===================================================================
--- /dev/null
+++ b/arch/x86/kernel/paravirt-spinlocks.c
@@ -0,0 +1,31 @@
+/*
+ * Split spinlock implementation out into its own file, so it can be
+ * compiled in a FTRACE-compatible way.
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+
+#include <asm/paravirt.h>
+
+struct pv_lock_ops pv_lock_ops = {
+#ifdef CONFIG_SMP
+ .spin_is_locked = __ticket_spin_is_locked,
+ .spin_is_contended = __ticket_spin_is_contended,
+
+ .spin_lock = __ticket_spin_lock,
+ .spin_trylock = __ticket_spin_trylock,
+ .spin_unlock = __ticket_spin_unlock,
+#endif
+};
+EXPORT_SYMBOL_GPL(pv_lock_ops);
+
+void __init paravirt_use_bytelocks(void)
+{
+#ifdef CONFIG_SMP
+ pv_lock_ops.spin_is_locked = __byte_spin_is_locked;
+ pv_lock_ops.spin_is_contended = __byte_spin_is_contended;
+ pv_lock_ops.spin_lock = __byte_spin_lock;
+ pv_lock_ops.spin_trylock = __byte_spin_trylock;
+ pv_lock_ops.spin_unlock = __byte_spin_unlock;
+#endif
+}
===================================================================
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -270,17 +270,6 @@
return __get_cpu_var(paravirt_lazy_mode);
}
-void __init paravirt_use_bytelocks(void)
-{
-#ifdef CONFIG_SMP
- pv_lock_ops.spin_is_locked = __byte_spin_is_locked;
- pv_lock_ops.spin_is_contended = __byte_spin_is_contended;
- pv_lock_ops.spin_lock = __byte_spin_lock;
- pv_lock_ops.spin_trylock = __byte_spin_trylock;
- pv_lock_ops.spin_unlock = __byte_spin_unlock;
-#endif
-}
-
struct pv_info pv_info = {
.name = "bare hardware",
.paravirt_enabled = 0,
@@ -466,18 +455,6 @@
.set_fixmap = native_set_fixmap,
};
-struct pv_lock_ops pv_lock_ops = {
-#ifdef CONFIG_SMP
- .spin_is_locked = __ticket_spin_is_locked,
- .spin_is_contended = __ticket_spin_is_contended,
-
- .spin_lock = __ticket_spin_lock,
- .spin_trylock = __ticket_spin_trylock,
- .spin_unlock = __ticket_spin_unlock,
-#endif
-};
-EXPORT_SYMBOL_GPL(pv_lock_ops);
-
EXPORT_SYMBOL_GPL(pv_time_ops);
EXPORT_SYMBOL (pv_cpu_ops);
EXPORT_SYMBOL (pv_mmu_ops);
===================================================================
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -1,4 +1,10 @@
+ifdef CONFIG_FTRACE
+# Do not profile debug and lowlevel utilities
+CFLAGS_REMOVE_spinlock.o = -pg
+CFLAGS_REMOVE_time.o = -pg
+endif
+
obj-y := enlighten.o setup.o multicalls.o mmu.o \
time.o xen-asm_$(BITS).o grant-table.o suspend.o
-obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SMP) += smp.o spinlock.o
===================================================================
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -15,7 +15,6 @@
* This does not handle HOTPLUG_CPU yet.
*/
#include <linux/sched.h>
-#include <linux/kernel_stat.h>
#include <linux/err.h>
#include <linux/smp.h>
@@ -35,8 +34,6 @@
#include "xen-ops.h"
#include "mmu.h"
-
-static void __cpuinit xen_init_lock_cpu(int cpu);
cpumask_t xen_cpu_initialized_map;
@@ -419,170 +416,6 @@
return IRQ_HANDLED;
}
-struct xen_spinlock {
- unsigned char lock; /* 0 -> free; 1 -> locked */
- unsigned short spinners; /* count of waiting cpus */
-};
-
-static int xen_spin_is_locked(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
-
- return xl->lock != 0;
-}
-
-static int xen_spin_is_contended(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
-
- /* Not strictly true; this is only the count of contended
- lock-takers entering the slow path. */
- return xl->spinners != 0;
-}
-
-static int xen_spin_trylock(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
- u8 old = 1;
-
- asm("xchgb %b0,%1"
- : "+q" (old), "+m" (xl->lock) : : "memory");
-
- return old == 0;
-}
-
-static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
-static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners);
-
-static inline void spinning_lock(struct xen_spinlock *xl)
-{
- __get_cpu_var(lock_spinners) = xl;
- wmb(); /* set lock of interest before count */
- asm(LOCK_PREFIX " incw %0"
- : "+m" (xl->spinners) : : "memory");
-}
-
-static inline void unspinning_lock(struct xen_spinlock *xl)
-{
- asm(LOCK_PREFIX " decw %0"
- : "+m" (xl->spinners) : : "memory");
- wmb(); /* decrement count before clearing lock */
- __get_cpu_var(lock_spinners) = NULL;
-}
-
-static noinline int xen_spin_lock_slow(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
- int irq = __get_cpu_var(lock_kicker_irq);
- int ret;
-
- /* If kicker interrupts not initialized yet, just spin */
- if (irq == -1)
- return 0;
-
- /* announce we're spinning */
- spinning_lock(xl);
-
- /* clear pending */
- xen_clear_irq_pending(irq);
-
- /* check again make sure it didn't become free while
- we weren't looking */
- ret = xen_spin_trylock(lock);
- if (ret)
- goto out;
-
- /* block until irq becomes pending */
- xen_poll_irq(irq);
- kstat_this_cpu.irqs[irq]++;
-
-out:
- unspinning_lock(xl);
- return ret;
-}
-
-static void xen_spin_lock(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
- int timeout;
- u8 oldval;
-
- do {
- timeout = 1 << 10;
-
- asm("1: xchgb %1,%0\n"
- " testb %1,%1\n"
- " jz 3f\n"
- "2: rep;nop\n"
- " cmpb $0,%0\n"
- " je 1b\n"
- " dec %2\n"
- " jnz 2b\n"
- "3:\n"
- : "+m" (xl->lock), "=q" (oldval), "+r" (timeout)
- : "1" (1)
- : "memory");
-
- } while (unlikely(oldval != 0 && !xen_spin_lock_slow(lock)));
-}
-
-static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl)
-{
- int cpu;
-
- for_each_online_cpu(cpu) {
- /* XXX should mix up next cpu selection */
- if (per_cpu(lock_spinners, cpu) == xl) {
- xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
- break;
- }
- }
-}
-
-static void xen_spin_unlock(struct raw_spinlock *lock)
-{
- struct xen_spinlock *xl = (struct xen_spinlock *)lock;
-
- smp_wmb(); /* make sure no writes get moved after unlock */
- xl->lock = 0; /* release lock */
-
- /* make sure unlock happens before kick */
- barrier();
-
- if (unlikely(xl->spinners))
- xen_spin_unlock_slow(xl);
-}
-
-static __cpuinit void xen_init_lock_cpu(int cpu)
-{
- int irq;
- const char *name;
-
- name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
- irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
- cpu,
- xen_reschedule_interrupt,
- IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
- name,
- NULL);
-
- if (irq >= 0) {
- disable_irq(irq); /* make sure it's never delivered */
- per_cpu(lock_kicker_irq, cpu) = irq;
- }
-
- printk("cpu %d spinlock event irq %d\n", cpu, irq);
-}
-
-static void __init xen_init_spinlocks(void)
-{
- pv_lock_ops.spin_is_locked = xen_spin_is_locked;
- pv_lock_ops.spin_is_contended = xen_spin_is_contended;
- pv_lock_ops.spin_lock = xen_spin_lock;
- pv_lock_ops.spin_trylock = xen_spin_trylock;
- pv_lock_ops.spin_unlock = xen_spin_unlock;
-}
-
static const struct smp_ops xen_smp_ops __initdata = {
.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
.smp_prepare_cpus = xen_smp_prepare_cpus,
===================================================================
--- /dev/null
+++ b/arch/x86/xen/spinlock.c
@@ -0,0 +1,183 @@
+/*
+ * Split spinlock implementation out into its own file, so it can be
+ * compiled in a FTRACE-compatible way.
+ */
+#include <linux/kernel_stat.h>
+#include <linux/spinlock.h>
+
+#include <asm/paravirt.h>
+
+#include <xen/interface/xen.h>
+#include <xen/events.h>
+
+#include "xen-ops.h"
+
+struct xen_spinlock {
+ unsigned char lock; /* 0 -> free; 1 -> locked */
+ unsigned short spinners; /* count of waiting cpus */
+};
+
+static int xen_spin_is_locked(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+
+ return xl->lock != 0;
+}
+
+static int xen_spin_is_contended(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+
+ /* Not strictly true; this is only the count of contended
+ lock-takers entering the slow path. */
+ return xl->spinners != 0;
+}
+
+static int xen_spin_trylock(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+ u8 old = 1;
+
+ asm("xchgb %b0,%1"
+ : "+q" (old), "+m" (xl->lock) : : "memory");
+
+ return old == 0;
+}
+
+static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
+static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners);
+
+static inline void spinning_lock(struct xen_spinlock *xl)
+{
+ __get_cpu_var(lock_spinners) = xl;
+ wmb(); /* set lock of interest before count */
+ asm(LOCK_PREFIX " incw %0"
+ : "+m" (xl->spinners) : : "memory");
+}
+
+static inline void unspinning_lock(struct xen_spinlock *xl)
+{
+ asm(LOCK_PREFIX " decw %0"
+ : "+m" (xl->spinners) : : "memory");
+ wmb(); /* decrement count before clearing lock */
+ __get_cpu_var(lock_spinners) = NULL;
+}
+
+static noinline int xen_spin_lock_slow(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+ int irq = __get_cpu_var(lock_kicker_irq);
+ int ret;
+
+ /* If kicker interrupts not initialized yet, just spin */
+ if (irq == -1)
+ return 0;
+
+ /* announce we're spinning */
+ spinning_lock(xl);
+
+ /* clear pending */
+ xen_clear_irq_pending(irq);
+
+ /* check again make sure it didn't become free while
+ we weren't looking */
+ ret = xen_spin_trylock(lock);
+ if (ret)
+ goto out;
+
+ /* block until irq becomes pending */
+ xen_poll_irq(irq);
+ kstat_this_cpu.irqs[irq]++;
+
+out:
+ unspinning_lock(xl);
+ return ret;
+}
+
+static void xen_spin_lock(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+ int timeout;
+ u8 oldval;
+
+ do {
+ timeout = 1 << 10;
+
+ asm("1: xchgb %1,%0\n"
+ " testb %1,%1\n"
+ " jz 3f\n"
+ "2: rep;nop\n"
+ " cmpb $0,%0\n"
+ " je 1b\n"
+ " dec %2\n"
+ " jnz 2b\n"
+ "3:\n"
+ : "+m" (xl->lock), "=q" (oldval), "+r" (timeout)
+ : "1" (1)
+ : "memory");
+
+ } while (unlikely(oldval != 0 && !xen_spin_lock_slow(lock)));
+}
+
+static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ /* XXX should mix up next cpu selection */
+ if (per_cpu(lock_spinners, cpu) == xl) {
+ xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
+ break;
+ }
+ }
+}
+
+static void xen_spin_unlock(struct raw_spinlock *lock)
+{
+ struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+
+ smp_wmb(); /* make sure no writes get moved after unlock */
+ xl->lock = 0; /* release lock */
+
+ /* make sure unlock happens before kick */
+ barrier();
+
+ if (unlikely(xl->spinners))
+ xen_spin_unlock_slow(xl);
+}
+
+static irqreturn_t dummy_handler(int irq, void *dev_id)
+{
+ BUG();
+ return IRQ_HANDLED;
+}
+
+void __cpuinit xen_init_lock_cpu(int cpu)
+{
+ int irq;
+ const char *name;
+
+ name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
+ irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
+ cpu,
+ dummy_handler,
+ IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
+ name,
+ NULL);
+
+ if (irq >= 0) {
+ disable_irq(irq); /* make sure it's never delivered */
+ per_cpu(lock_kicker_irq, cpu) = irq;
+ }
+
+ printk("cpu %d spinlock event irq %d\n", cpu, irq);
+}
+
+void __init xen_init_spinlocks(void)
+{
+ pv_lock_ops.spin_is_locked = xen_spin_is_locked;
+ pv_lock_ops.spin_is_contended = xen_spin_is_contended;
+ pv_lock_ops.spin_lock = xen_spin_lock;
+ pv_lock_ops.spin_trylock = xen_spin_trylock;
+ pv_lock_ops.spin_unlock = xen_spin_unlock;
+}
===================================================================
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -50,6 +50,9 @@
#ifdef CONFIG_SMP
void xen_smp_init(void);
+void __init xen_init_spinlocks(void);
+__cpuinit void xen_init_lock_cpu(int cpu);
+
extern cpumask_t xen_cpu_initialized_map;
#else
static inline void xen_smp_init(void) {}
--
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