arch/x86/include/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_BARRIER_H
   3 #define _ASM_X86_BARRIER_H
   4
   5 #include <asm/alternative.h>
   6 #include <asm/nops.h>
   7
   8 /*
   9  * Force strict CPU ordering.
  10  * And yes, this might be required on UP too when we're talking
  11  * to devices.
  12  */
  13
  14 #ifdef CONFIG_X86_32
  15 #define mb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "mfence", \
  16                                       X86_FEATURE_XMM2) ::: "memory", "cc")
  17 #define rmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "lfence", \
  18                                        X86_FEATURE_XMM2) ::: "memory", "cc")
  19 #define wmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \
  20                                        X86_FEATURE_XMM2) ::: "memory", "cc")
  21 #else
  22 #define mb()    asm volatile("mfence":::"memory")
  23 #define rmb()   asm volatile("lfence":::"memory")
  24 #define wmb()   asm volatile("sfence" ::: "memory")
  25 #endif
  26
  27 #ifdef CONFIG_X86_PPRO_FENCE
  28 #define dma_rmb()       rmb()
  29 #else
  30 #define dma_rmb()       barrier()
  31 #endif
  32 #define dma_wmb()       barrier()
  33
  34 #ifdef CONFIG_X86_32
  35 #define __smp_mb()      asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc")
  36 #else
  37 #define __smp_mb()      asm volatile("lock; addl $0,-4(%%rsp)" ::: "memory", "cc")
  38 #endif
  39 #define __smp_rmb()     dma_rmb()
  40 #define __smp_wmb()     barrier()
  41 #define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
  42
  43 #if defined(CONFIG_X86_PPRO_FENCE)
  44
  45 /*
  46  * For this option x86 doesn't have a strong TSO memory
  47  * model and we should fall back to full barriers.
  48  */
  49
  50 #define __smp_store_release(p, v)                                       \
  51 do {                                                                    \
  52         compiletime_assert_atomic_type(*p);                             \
  53         __smp_mb();                                                     \
  54         WRITE_ONCE(*p, v);                                              \
  55 } while (0)
  56
  57 #define __smp_load_acquire(p)                                           \
  58 ({                                                                      \
  59         typeof(*p) ___p1 = READ_ONCE(*p);                               \
  60         compiletime_assert_atomic_type(*p);                             \
  61         __smp_mb();                                                     \
  62         ___p1;                                                          \
  63 })
  64
  65 #else /* regular x86 TSO memory ordering */
  66
  67 #define __smp_store_release(p, v)                                       \
  68 do {                                                                    \
  69         compiletime_assert_atomic_type(*p);                             \
  70         barrier();                                                      \
  71         WRITE_ONCE(*p, v);                                              \
  72 } while (0)
  73
  74 #define __smp_load_acquire(p)                                           \
  75 ({                                                                      \
  76         typeof(*p) ___p1 = READ_ONCE(*p);                               \
  77         compiletime_assert_atomic_type(*p);                             \
  78         barrier();                                                      \
  79         ___p1;                                                          \
  80 })
  81
  82 #endif
  83
  84 /* Atomic operations are already serializing on x86 */
  85 #define __smp_mb__before_atomic()       barrier()
  86 #define __smp_mb__after_atomic()        barrier()
  87
  88 #include <asm-generic/barrier.h>
  89
  90 #endif /* _ASM_X86_BARRIER_H */