tools/virtio/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <stdlib.h>
   3 #if defined(__i386__) || defined(__x86_64__)
   4 #define barrier() asm volatile("" ::: "memory")
   5 #define virt_mb() __sync_synchronize()
   6 #define virt_rmb() barrier()
   7 #define virt_wmb() barrier()
   8 /* Atomic store should be enough, but gcc generates worse code in that case. */
   9 #define virt_store_mb(var, value)  do { \
  10         typeof(var) virt_store_mb_value = (value); \
  11         __atomic_exchange(&(var), &virt_store_mb_value, &virt_store_mb_value, \
  12                           __ATOMIC_SEQ_CST); \
  13         barrier(); \
  14 } while (0);
  15 /* Weak barriers should be used. If not - it's a bug */
  16 # define mb() abort()
  17 # define dma_rmb() abort()
  18 # define dma_wmb() abort()
  19 #elif defined(__aarch64__)
  20 #define dmb(opt) asm volatile("dmb " #opt : : : "memory")
  21 #define virt_mb() __sync_synchronize()
  22 #define virt_rmb() dmb(ishld)
  23 #define virt_wmb() dmb(ishst)
  24 #define virt_store_mb(var, value)  do { WRITE_ONCE(var, value); dmb(ish); } while (0)
  25 /* Weak barriers should be used. If not - it's a bug */
  26 # define mb() abort()
  27 # define dma_rmb() abort()
  28 # define dma_wmb() abort()
  29 #else
  30 #error Please fill in barrier macros
  31 #endif
  32