Release 4.16 arch/x86/include/asm/barrier.h

/* SPDX-License-Identifier: GPL-2.0 */
#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 might be required on UP too when we're talking
 * to devices.
 */

#ifdef CONFIG_X86_32

#define mb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "mfence", \
                                      X86_FEATURE_XMM2) ::: "memory", "cc")

#define rmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "lfence", \
                                       X86_FEATURE_XMM2) ::: "memory", "cc")

#define wmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \
                                       X86_FEATURE_XMM2) ::: "memory", "cc")
#else

#define mb() 	asm volatile("mfence":::"memory")

#define rmb()	asm volatile("lfence":::"memory")

#define wmb()	asm volatile("sfence" ::: "memory")
#endif

/**
 * array_index_mask_nospec() - generate a mask that is ~0UL when the
 *      bounds check succeeds and 0 otherwise
 * @index: array element index
 * @size: number of elements in array
 *
 * Returns:
 *     0 - (index < size)
 */


static inline unsigned long array_index_mask_nospec(unsigned long index,
		unsigned long size)
{
	unsigned long mask;

	asm ("cmp %1,%2; sbb %0,%0;"
                        :"=r" (mask)
                        :"g"(size),"r" (index)
                        :"cc");
	return mask;
}

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/* Override the default implementation from linux/nospec.h. */

#define array_index_mask_nospec array_index_mask_nospec

/* Prevent speculative execution past this barrier. */

#define barrier_nospec() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \
                                           "lfence", X86_FEATURE_LFENCE_RDTSC)


#define dma_rmb()	barrier()

#define dma_wmb()	barrier()

#ifdef CONFIG_X86_32

#define __smp_mb()	asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc")
#else

#define __smp_mb()	asm volatile("lock; addl $0,-4(%%rsp)" ::: "memory", "cc")
#endif

#define __smp_rmb()	dma_rmb()

#define __smp_wmb()	barrier()

#define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)


#define __smp_store_release(p, v)					\
do {                                                                    \
        compiletime_assert_atomic_type(*p);                             \
        barrier();                                                      \
        WRITE_ONCE(*p, v);                                              \
} while (0)


#define __smp_load_acquire(p)						\
({                                                                      \
        typeof(*p) ___p1 = READ_ONCE(*p);                               \
        compiletime_assert_atomic_type(*p);                             \
        barrier();                                                      \
        ___p1;                                                          \
})

/* Atomic operations are already serializing on x86 */

#define __smp_mb__before_atomic()	barrier()

#define __smp_mb__after_atomic()	barrier()

#include <asm-generic/barrier.h>

#endif /* _ASM_X86_BARRIER_H */
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Directory: arch/x86/include/asm

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