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#ifndef _ASM_X86_BARRIER_H
#define _ASM_X86_BARRIER_H
#include <asm/alternative.h>
#include <asm/nops.h>
/*
* Force strict CPU ordering.
* And yes, this is required on UP too when we're talking
* to devices.
*/
#ifdef CONFIG_X86_32
/*
* Some non-Intel clones support out of order store. wmb() ceases to be a
* nop for these.
*/
#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
#else
#define mb() asm volatile("mfence":::"memory")
#define rmb() asm volatile("lfence":::"memory")
#define wmb() asm volatile("sfence" ::: "memory")
#endif
#ifdef CONFIG_X86_PPRO_FENCE
#define dma_rmb() rmb()
#else
#define dma_rmb() barrier()
#endif
#define dma_wmb() barrier()
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() dma_rmb()
#define smp_wmb() barrier()
#define smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
#else /* !SMP */
#define smp_mb() barrier()
#define smp_rmb() barrier()
#define smp_wmb() barrier()
#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
#endif /* SMP */
#define read_barrier_depends() do { } while (0)
#define smp_read_barrier_depends() do { } while (0)
#if defined(CONFIG_X86_PPRO_FENCE)
/*
* For this option x86 doesn't have a strong TSO memory
* model and we should fall back to full barriers.
*/
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
ACCESS_ONCE(*p) = (v); \
} while (0)
#define smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = ACCESS_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
})
#else /* regular x86 TSO memory ordering */
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
ACCESS_ONCE(*p) = (v); \
} while (0)
#define smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = ACCESS_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
})
#endif
/* Atomic operations are already serializing on x86 */
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
/*
* Stop RDTSC speculation. This is needed when you need to use RDTSC
* (or get_cycles or vread that possibly accesses the TSC) in a defined
* code region.
*/
static __always_inline void rdtsc_barrier(void)
{
alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC,
"lfence", X86_FEATURE_LFENCE_RDTSC);
}
#endif /* _ASM_X86_BARRIER_H */
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