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/* SPDX-License-Identifier: GPL-2.0 */
* Copyright (C) 1999 Cort Dougan <>
#include <asm/asm-const.h>
#ifndef __ASSEMBLY__
#include <asm/ppc-opcode.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.
* 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(CONFIG_PPC64) || defined(CONFIG_PPC_E500MC)
# define SMPWMB eieio
/* clang defines this macro for a builtin, which will not work with runtime patching */
#undef __lwsync
#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; \
#elif defined(CONFIG_PPC_FSL_BOOK3E)
#define NOSPEC_BARRIER_SLOT nop; nop
* Prevent execution of subsequent instructions until preceding branches have
* been fully resolved and are no longer executing speculatively.
// This also acts as a compiler barrier due to the memory clobber.
#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
#define barrier_nospec_asm
#define barrier_nospec()
* pmem_wmb() ensures that all stores for which the modification
* are written to persistent storage by preceding dcbfps/dcbstps
* instructions have updated persistent storage before any data
* access or data transfer caused by subsequent instructions is
* initiated.
#define pmem_wmb() __asm__ __volatile__(PPC_PHWSYNC ::: "memory")
#include <asm-generic/barrier.h>