forked from Minki/linux
b92b8b35a2
Since set_mb() is really about an smp_mb() -- not a IO/DMA barrier like mb() rename it to match the recent smp_load_acquire() and smp_store_release(). Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
106 lines
2.6 KiB
C
106 lines
2.6 KiB
C
#ifndef _ASM_X86_BARRIER_H
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#define _ASM_X86_BARRIER_H
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#include <asm/alternative.h>
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#include <asm/nops.h>
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/*
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* Force strict CPU ordering.
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* And yes, this is required on UP too when we're talking
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* to devices.
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*/
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#ifdef CONFIG_X86_32
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/*
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* Some non-Intel clones support out of order store. wmb() ceases to be a
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* nop for these.
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*/
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#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
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#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
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#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
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#else
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#define mb() asm volatile("mfence":::"memory")
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#define rmb() asm volatile("lfence":::"memory")
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#define wmb() asm volatile("sfence" ::: "memory")
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#endif
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#ifdef CONFIG_X86_PPRO_FENCE
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#define dma_rmb() rmb()
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#else
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#define dma_rmb() barrier()
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#endif
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#define dma_wmb() barrier()
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#ifdef CONFIG_SMP
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#define smp_mb() mb()
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#define smp_rmb() dma_rmb()
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#define smp_wmb() barrier()
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#define smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
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#else /* !SMP */
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#define smp_mb() barrier()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
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#endif /* SMP */
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#define read_barrier_depends() do { } while (0)
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#define smp_read_barrier_depends() do { } while (0)
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#if defined(CONFIG_X86_PPRO_FENCE)
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/*
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* For this option x86 doesn't have a strong TSO memory
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* model and we should fall back to full barriers.
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*/
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#define smp_store_release(p, v) \
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do { \
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compiletime_assert_atomic_type(*p); \
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smp_mb(); \
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ACCESS_ONCE(*p) = (v); \
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} while (0)
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#define smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = ACCESS_ONCE(*p); \
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compiletime_assert_atomic_type(*p); \
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smp_mb(); \
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___p1; \
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})
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#else /* regular x86 TSO memory ordering */
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#define smp_store_release(p, v) \
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do { \
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compiletime_assert_atomic_type(*p); \
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barrier(); \
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ACCESS_ONCE(*p) = (v); \
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} while (0)
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#define smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = ACCESS_ONCE(*p); \
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compiletime_assert_atomic_type(*p); \
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barrier(); \
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___p1; \
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})
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#endif
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/* Atomic operations are already serializing on x86 */
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#define smp_mb__before_atomic() barrier()
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#define smp_mb__after_atomic() barrier()
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/*
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* Stop RDTSC speculation. This is needed when you need to use RDTSC
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* (or get_cycles or vread that possibly accesses the TSC) in a defined
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* code region.
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*/
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static __always_inline void rdtsc_barrier(void)
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{
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alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC,
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"lfence", X86_FEATURE_LFENCE_RDTSC);
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}
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#endif /* _ASM_X86_BARRIER_H */
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