Release 4.18 arch/powerpc/include/asm/barrier.h
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
*/
#ifndef _ASM_POWERPC_BARRIER_H
#define _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.
* read_barrier_depends() prevents data-dependent loads being reordered
* across this point (nop on PPC).
*
* *mb() variants without smp_ prefix must order all types of memory
* operations with one another. sync is the only instruction sufficient
* to do this.
*
* For the smp_ barriers, ordering is for cacheable memory operations
* only. We have to use the sync instruction for smp_mb(), since lwsync
* doesn't order loads with respect to previous stores. Lwsync can be
* used for smp_rmb() and smp_wmb().
*
* However, on CPUs that don't support lwsync, lwsync actually maps to a
* heavy-weight sync, so smp_wmb() can be a lighter-weight eieio.
*/
#define mb() __asm__ __volatile__ ("sync" : : : "memory")
#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
#define wmb() __asm__ __volatile__ ("sync" : : : "memory")
/* The sub-arch has lwsync */
#if defined(__powerpc64__) || defined(CONFIG_PPC_E500MC)
# define SMPWMB LWSYNC
#else
# define SMPWMB eieio
#endif
#define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
#define dma_rmb() __lwsync()
#define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
#define __smp_lwsync() __lwsync()
#define __smp_mb() mb()
#define __smp_rmb() __lwsync()
#define __smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
/*
* This is a barrier which prevents following instructions from being
* started until the value of the argument x is known. For example, if
* x is a variable loaded from memory, this prevents following
* instructions from being executed until the load has been performed.
*/
#define data_barrier(x) \
asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory");
#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
__smp_lwsync(); \
WRITE_ONCE(*p, v); \
} while (0)
#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
__smp_lwsync(); \
___p1; \
})
#ifdef CONFIG_PPC_BOOK3S_64
/*
* Prevent execution of subsequent instructions until preceding branches have
* been fully resolved and are no longer executing speculatively.
*/
#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop
// This also acts as a compiler barrier due to the memory clobber.
#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
#else /* !CONFIG_PPC_BOOK3S_64 */
#define barrier_nospec_asm
#define barrier_nospec()
#endif
#include <asm-generic/barrier.h>
#endif /* _ASM_POWERPC_BARRIER_H */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| David Howells | 58 | 40.85% | 1 | 11.11% |
| Michal Suchanek | 26 | 18.31% | 2 | 22.22% |
| Peter Zijlstra | 20 | 14.08% | 1 | 11.11% |
| Alexander Duyck | 14 | 9.86% | 1 | 11.11% |
| Nicholas Piggin | 12 | 8.45% | 1 | 11.11% |
| Michael S. Tsirkin | 11 | 7.75% | 2 | 22.22% |
| Greg Kroah-Hartman | 1 | 0.70% | 1 | 11.11% |
| Total | 142 | 100.00% | 9 | 100.00% |
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