tools/virtio/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #if defined(__i386__) || defined(__x86_64__)
   3 #define barrier() asm volatile("" ::: "memory")
   4 #define virt_mb() __sync_synchronize()
   5 #define virt_rmb() barrier()
   6 #define virt_wmb() barrier()
   7 /* Atomic store should be enough, but gcc generates worse code in that case. */
   8 #define virt_store_mb(var, value)  do { \
   9         typeof(var) virt_store_mb_value = (value); \
  10         __atomic_exchange(&(var), &virt_store_mb_value, &virt_store_mb_value, \
  11                           __ATOMIC_SEQ_CST); \
  12         barrier(); \
  13 } while (0);
  14 /* Weak barriers should be used. If not - it's a bug */
  15 # define mb() abort()
  16 # define dma_rmb() abort()
  17 # define dma_wmb() abort()
  18 #else
  19 #error Please fill in barrier macros
  20 #endif
  21