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x86: consolidate spinlock.h
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The cli and sti instructions need to be replaced by paravirt hooks.
For the i386 architecture, this is already done. The code requirements
aren't much different from x86_64 POV, so this part is consolidated in
the common header

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Glauber de Oliveira Costa authored and Ingo Molnar committed Jan 30, 2008
1 parent 6abcd98 commit 2fed0c5
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Showing 3 changed files with 64 additions and 58 deletions.
14 changes: 14 additions & 0 deletions include/asm-x86/spinlock.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,19 @@
#ifndef _X86_SPINLOCK_H_
#define _X86_SPINLOCK_H_

#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
#define CLI_STRING "cli"
#define STI_STRING "sti"
#define CLI_STI_CLOBBERS
#define CLI_STI_INPUT_ARGS
#endif /* CONFIG_PARAVIRT */

#ifdef CONFIG_X86_32
# include "spinlock_32.h"
#else
# include "spinlock_64.h"
#endif

#endif
71 changes: 26 additions & 45 deletions include/asm-x86/spinlock_32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -5,16 +5,6 @@
#include <asm/rwlock.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <linux/compiler.h>

#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
#define CLI_STRING "cli"
#define STI_STRING "sti"
#define CLI_STI_CLOBBERS
#define CLI_STI_INPUT_ARGS
#endif /* CONFIG_PARAVIRT */

/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
Expand All @@ -27,23 +17,24 @@
* (the type definitions are in asm/spinlock_types.h)
*/

static inline int __raw_spin_is_locked(raw_spinlock_t *x)
static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
{
return *(volatile signed char *)(&(x)->slock) <= 0;
return *(volatile signed char *)(&(lock)->slock) <= 0;
}

static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
asm volatile("\n1:\t"
LOCK_PREFIX " ; decb %0\n\t"
"jns 3f\n"
"2:\t"
"rep;nop\n\t"
"cmpb $0,%0\n\t"
"jle 2b\n\t"
"jmp 1b\n"
"3:\n\t"
: "+m" (lock->slock) : : "memory");
asm volatile(
"\n1:\t"
LOCK_PREFIX " ; decb %0\n\t"
"jns 3f\n"
"2:\t"
"rep;nop\n\t"
"cmpb $0,%0\n\t"
"jle 2b\n\t"
"jmp 1b\n"
"3:\n\t"
: "+m" (lock->slock) : : "memory");
}

/*
Expand All @@ -55,7 +46,8 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
* irq-traced, but on CONFIG_TRACE_IRQFLAGS we never use this variant.
*/
#ifndef CONFIG_PROVE_LOCKING
static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
static inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
unsigned long flags)
{
asm volatile(
"\n1:\t"
Expand All @@ -79,18 +71,20 @@ static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long fla
"5:\n\t"
: [slock] "+m" (lock->slock)
: [flags] "r" (flags)
CLI_STI_INPUT_ARGS
CLI_STI_INPUT_ARGS
: "memory" CLI_STI_CLOBBERS);
}
#endif

static inline int __raw_spin_trylock(raw_spinlock_t *lock)
{
char oldval;
signed char oldval;

asm volatile(
"xchgb %b0,%1"
:"=q" (oldval), "+m" (lock->slock)
:"0" (0) : "memory");

return oldval > 0;
}

Expand All @@ -112,7 +106,7 @@ static inline void __raw_spin_unlock(raw_spinlock_t *lock)

static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
char oldval = 1;
unsigned char oldval = 1;

asm volatile("xchgb %b0, %1"
: "=q" (oldval), "+m" (lock->slock)
Expand All @@ -139,31 +133,16 @@ static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
*
* On x86, we implement read-write locks as a 32-bit counter
* with the high bit (sign) being the "contended" bit.
*
* The inline assembly is non-obvious. Think about it.
*
* Changed to use the same technique as rw semaphores. See
* semaphore.h for details. -ben
*
* the helpers are in arch/i386/kernel/semaphore.c
*/

/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
static inline int __raw_read_can_lock(raw_rwlock_t *x)
static inline int __raw_read_can_lock(raw_rwlock_t *lock)
{
return (int)(x)->lock > 0;
return (int)(lock)->lock > 0;
}

/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
static inline int __raw_write_can_lock(raw_rwlock_t *x)
static inline int __raw_write_can_lock(raw_rwlock_t *lock)
{
return (x)->lock == RW_LOCK_BIAS;
return (lock)->lock == RW_LOCK_BIAS;
}

static inline void __raw_read_lock(raw_rwlock_t *rw)
Expand All @@ -187,6 +166,7 @@ static inline void __raw_write_lock(raw_rwlock_t *rw)
static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;

atomic_dec(count);
if (atomic_read(count) >= 0)
return 1;
Expand All @@ -197,6 +177,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *lock)
static inline int __raw_write_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;

if (atomic_sub_and_test(RW_LOCK_BIAS, count))
return 1;
atomic_add(RW_LOCK_BIAS, count);
Expand Down
37 changes: 24 additions & 13 deletions include/asm-x86/spinlock_64.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,35 +33,44 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
"cmpl $0,%0\n\t"
"jle 3b\n\t"
"jmp 1b\n"
"2:\t" : "=m" (lock->slock) : : "memory");
"2:\t"
: "=m" (lock->slock) : : "memory");
}

/*
* Same as __raw_spin_lock, but reenable interrupts during spinning.
* It is easier for the lock validator if interrupts are not re-enabled
* in the middle of a lock-acquire. This is a performance feature anyway
* so we turn it off:
*
* NOTE: there's an irqs-on section here, which normally would have to be
* irq-traced, but on CONFIG_TRACE_IRQFLAGS we never use this variant.
*/
#ifndef CONFIG_PROVE_LOCKING
static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
static inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
unsigned long flags)
{
asm volatile(
"\n1:\t"
LOCK_PREFIX " ; decl %0\n\t"
"jns 5f\n"
"testl $0x200, %1\n\t" /* interrupts were disabled? */
"jz 4f\n\t"
"sti\n"
STI_STRING "\n"
"3:\t"
"rep;nop\n\t"
"cmpl $0, %0\n\t"
"jle 3b\n\t"
"cli\n\t"
CLI_STRING "\n\t"
"jmp 1b\n"
"4:\t"
"rep;nop\n\t"
"cmpl $0, %0\n\t"
"jg 1b\n\t"
"jmp 4b\n"
"5:\n\t"
: "+m" (lock->slock) : "r" ((unsigned)flags) : "memory");
: "+m" (lock->slock)
: "r" ((unsigned)flags) CLI_STI_INPUT_ARGS
: "memory" CLI_STI_CLOBBERS);
}
#endif

Expand All @@ -79,7 +88,7 @@ static inline int __raw_spin_trylock(raw_spinlock_t *lock)

static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
asm volatile("movl $1,%0" :"=m" (lock->slock) :: "memory");
asm volatile("movl $1,%0" : "=m" (lock->slock) :: "memory");
}

static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
Expand Down Expand Up @@ -114,25 +123,26 @@ static inline int __raw_write_can_lock(raw_rwlock_t *lock)

static inline void __raw_read_lock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t"
asm volatile(LOCK_PREFIX " subl $1,(%0)\n\t"
"jns 1f\n"
"call __read_lock_failed\n"
"call __read_lock_failed\n\t"
"1:\n"
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
}

static inline void __raw_write_lock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t"
asm volatile(LOCK_PREFIX " subl %1,(%0)\n\t"
"jz 1f\n"
"\tcall __write_lock_failed\n\t"
"call __write_lock_failed\n\t"
"1:\n"
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
}

static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;

atomic_dec(count);
if (atomic_read(count) >= 0)
return 1;
Expand All @@ -143,6 +153,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *lock)
static inline int __raw_write_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;

if (atomic_sub_and_test(RW_LOCK_BIAS, count))
return 1;
atomic_add(RW_LOCK_BIAS, count);
Expand All @@ -151,12 +162,12 @@ static inline int __raw_write_trylock(raw_rwlock_t *lock)

static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX " ; incl %0" :"=m" (rw->lock) : : "memory");
asm volatile(LOCK_PREFIX "incl %0" :"=m" (rw->lock) : : "memory");
}

static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX " ; addl $" RW_LOCK_BIAS_STR ",%0"
asm volatile(LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ",%0"
: "=m" (rw->lock) : : "memory");
}

Expand Down

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