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Diffstat (limited to 'arch/powerpc/include/asm/barrier.h')
| -rw-r--r-- | arch/powerpc/include/asm/barrier.h | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h new file mode 100644 index 000000000..dc953d22e --- /dev/null +++ b/arch/powerpc/include/asm/barrier.h @@ -0,0 +1,106 @@ +/* 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 + +#include <asm/asm-const.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 + +/* 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; \ +}) + +#ifdef CONFIG_PPC_BOOK3S_64 +#define NOSPEC_BARRIER_SLOT nop +#elif defined(CONFIG_PPC_FSL_BOOK3E) +#define NOSPEC_BARRIER_SLOT nop; nop +#endif + +#ifdef CONFIG_PPC_BARRIER_NOSPEC +/* + * 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; NOSPEC_BARRIER_SLOT + +// 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_BARRIER_NOSPEC */ +#define barrier_nospec_asm +#define barrier_nospec() +#endif /* CONFIG_PPC_BARRIER_NOSPEC */ + +#include <asm-generic/barrier.h> + +#endif /* _ASM_POWERPC_BARRIER_H */ |