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x86: split spinlock implementations out into their own files
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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@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Jeremy Fitzhardinge authored and Ingo Molnar committed Jul 24, 2008
1 parent 338b9bb commit d5de884
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Showing 7 changed files with 226 additions and 193 deletions.
4 changes: 2 additions & 2 deletions arch/x86/kernel/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ ifdef CONFIG_FTRACE
# 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

#
Expand Down Expand Up @@ -89,7 +89,7 @@ obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
obj-$(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
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31 changes: 31 additions & 0 deletions arch/x86/kernel/paravirt-spinlocks.c
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Original file line number Diff line number Diff line change
@@ -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
}
23 changes: 0 additions & 23 deletions arch/x86/kernel/paravirt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -268,17 +268,6 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
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,
Expand Down Expand Up @@ -461,18 +450,6 @@ struct pv_mmu_ops pv_mmu_ops = {
.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);
Expand Down
8 changes: 7 additions & 1 deletion arch/x86/xen/Makefile
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Original file line number Diff line number Diff line change
@@ -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
167 changes: 0 additions & 167 deletions arch/x86/xen/smp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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>

Expand All @@ -36,8 +35,6 @@
#include "xen-ops.h"
#include "mmu.h"

static void __cpuinit xen_init_lock_cpu(int cpu);

cpumask_t xen_cpu_initialized_map;

static DEFINE_PER_CPU(int, resched_irq);
Expand Down Expand Up @@ -419,170 +416,6 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
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,
Expand Down
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