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author | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 13:20:03 +0400 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 13:20:03 +0400 |
commit | 96a388de5dc53a8b234b3fd41f3ae2cedc9ffd42 (patch) | |
tree | d947a467aa2da3140279617bc4b9b101640d7bf4 /include/asm-x86/spinlock_32.h | |
parent | 27bd0c955648646abf2a353a8371d28c37bcd982 (diff) | |
download | linux-96a388de5dc53a8b234b3fd41f3ae2cedc9ffd42.tar.xz |
i386/x86_64: move headers to include/asm-x86
Move the headers to include/asm-x86 and fixup the
header install make rules
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-x86/spinlock_32.h')
-rw-r--r-- | include/asm-x86/spinlock_32.h | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/include/asm-x86/spinlock_32.h b/include/asm-x86/spinlock_32.h new file mode 100644 index 000000000000..d3bcebed60ca --- /dev/null +++ b/include/asm-x86/spinlock_32.h @@ -0,0 +1,221 @@ +#ifndef __ASM_SPINLOCK_H +#define __ASM_SPINLOCK_H + +#include <asm/atomic.h> +#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 + * + * Simple spin lock operations. There are two variants, one clears IRQ's + * on the local processor, one does not. + * + * We make no fairness assumptions. They have a cost. + * + * (the type definitions are in asm/spinlock_types.h) + */ + +static inline int __raw_spin_is_locked(raw_spinlock_t *x) +{ + return *(volatile signed char *)(&(x)->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"); +} + +/* + * 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) +{ + asm volatile( + "\n1:\t" + LOCK_PREFIX " ; decb %[slock]\n\t" + "jns 5f\n" + "2:\t" + "testl $0x200, %[flags]\n\t" + "jz 4f\n\t" + STI_STRING "\n" + "3:\t" + "rep;nop\n\t" + "cmpb $0, %[slock]\n\t" + "jle 3b\n\t" + CLI_STRING "\n\t" + "jmp 1b\n" + "4:\t" + "rep;nop\n\t" + "cmpb $0, %[slock]\n\t" + "jg 1b\n\t" + "jmp 4b\n" + "5:\n\t" + : [slock] "+m" (lock->slock) + : [flags] "r" (flags) + CLI_STI_INPUT_ARGS + : "memory" CLI_STI_CLOBBERS); +} +#endif + +static inline int __raw_spin_trylock(raw_spinlock_t *lock) +{ + char oldval; + asm volatile( + "xchgb %b0,%1" + :"=q" (oldval), "+m" (lock->slock) + :"0" (0) : "memory"); + return oldval > 0; +} + +/* + * __raw_spin_unlock based on writing $1 to the low byte. + * This method works. Despite all the confusion. + * (except on PPro SMP or if we are using OOSTORE, so we use xchgb there) + * (PPro errata 66, 92) + */ + +#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE) + +static inline void __raw_spin_unlock(raw_spinlock_t *lock) +{ + asm volatile("movb $1,%0" : "+m" (lock->slock) :: "memory"); +} + +#else + +static inline void __raw_spin_unlock(raw_spinlock_t *lock) +{ + char oldval = 1; + + asm volatile("xchgb %b0, %1" + : "=q" (oldval), "+m" (lock->slock) + : "0" (oldval) : "memory"); +} + +#endif + +static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock) +{ + while (__raw_spin_is_locked(lock)) + cpu_relax(); +} + +/* + * Read-write spinlocks, allowing multiple readers + * but only one writer. + * + * NOTE! it is quite common to have readers in interrupts + * but no interrupt writers. For those circumstances we + * can "mix" irq-safe locks - any writer needs to get a + * irq-safe write-lock, but readers can get non-irqsafe + * read-locks. + * + * 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) +{ + return (int)(x)->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) +{ + return (x)->lock == RW_LOCK_BIAS; +} + +static inline void __raw_read_lock(raw_rwlock_t *rw) +{ + asm volatile(LOCK_PREFIX " subl $1,(%0)\n\t" + "jns 1f\n" + "call __read_lock_failed\n\t" + "1:\n" + ::"a" (rw) : "memory"); +} + +static inline void __raw_write_lock(raw_rwlock_t *rw) +{ + asm volatile(LOCK_PREFIX " subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" + "jz 1f\n" + "call __write_lock_failed\n\t" + "1:\n" + ::"a" (rw) : "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; + atomic_inc(count); + return 0; +} + +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); + return 0; +} + +static inline void __raw_read_unlock(raw_rwlock_t *rw) +{ + 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" + : "+m" (rw->lock) : : "memory"); +} + +#define _raw_spin_relax(lock) cpu_relax() +#define _raw_read_relax(lock) cpu_relax() +#define _raw_write_relax(lock) cpu_relax() + +#endif /* __ASM_SPINLOCK_H */ |