forked from Minki/linux
300b06d455
As on most architectures, on x86 read_barrier_depends and smp_read_barrier_depends are empty. Drop the local definitions and pull the generic ones from asm-generic/barrier.h instead: they are identical. This is in preparation to refactoring this code area. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
94 lines
2.2 KiB
C
94 lines
2.2 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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#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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WRITE_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 = READ_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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WRITE_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 = READ_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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#include <asm-generic/barrier.h>
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#endif /* _ASM_X86_BARRIER_H */
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