tools/arch/powerpc/include/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copied from the kernel sources:
   4  *
   5  * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
   6  */
   7 #ifndef _TOOLS_LINUX_ASM_POWERPC_BARRIER_H
   8 #define _TOOLS_LINUX_ASM_POWERPC_BARRIER_H
   9
  10 /*
  11  * Memory barrier.
  12  * The sync instruction guarantees that all memory accesses initiated
  13  * by this processor have been performed (with respect to all other
  14  * mechanisms that access memory).  The eieio instruction is a barrier
  15  * providing an ordering (separately) for (a) cacheable stores and (b)
  16  * loads and stores to non-cacheable memory (e.g. I/O devices).
  17  *
  18  * mb() prevents loads and stores being reordered across this point.
  19  * rmb() prevents loads being reordered across this point.
  20  * wmb() prevents stores being reordered across this point.
  21  *
  22  * *mb() variants without smp_ prefix must order all types of memory
  23  * operations with one another. sync is the only instruction sufficient
  24  * to do this.
  25  */
  26 #define mb()   __asm__ __volatile__ ("sync" : : : "memory")
  27 #define rmb()  __asm__ __volatile__ ("sync" : : : "memory")
  28 #define wmb()  __asm__ __volatile__ ("sync" : : : "memory")
  29
  30 #endif /* _TOOLS_LINUX_ASM_POWERPC_BARRIER_H */