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 #if defined(__powerpc64__) 31 #define smp_lwsync() __asm__ __volatile__ ("lwsync" : : : "memory") 32 33 #define smp_store_release(p, v) \ 34 do { \ 35 smp_lwsync(); \ 36 WRITE_ONCE(*p, v); \ 37 } while (0) 38 39 #define smp_load_acquire(p) \ 40 ({ \ 41 typeof(*p) ___p1 = READ_ONCE(*p); \ 42 smp_lwsync(); \ 43 ___p1; \ 44 }) 45 #endif /* defined(__powerpc64__) */ 46 #endif /* _TOOLS_LINUX_ASM_POWERPC_BARRIER_H */ 47