linux_old1/tools/arch/powerpc/include/asm/barrier.h

31 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copied from the kernel sources:
*
* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
*/
#ifndef _TOOLS_LINUX_ASM_POWERPC_BARRIER_H
#define _TOOLS_LINUX_ASM_POWERPC_BARRIER_H
/*
* Memory barrier.
* The sync instruction guarantees that all memory accesses initiated
* by this processor have been performed (with respect to all other
* mechanisms that access memory). The eieio instruction is a barrier
* providing an ordering (separately) for (a) cacheable stores and (b)
* loads and stores to non-cacheable memory (e.g. I/O devices).
*
* mb() prevents loads and stores being reordered across this point.
* rmb() prevents loads being reordered across this point.
* wmb() prevents stores being reordered across this point.
*
* *mb() variants without smp_ prefix must order all types of memory
* operations with one another. sync is the only instruction sufficient
* to do this.
*/
#define mb() __asm__ __volatile__ ("sync" : : : "memory")
#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
#define wmb() __asm__ __volatile__ ("sync" : : : "memory")
#endif /* _TOOLS_LINUX_ASM_POWERPC_BARRIER_H */