dcc29e3f43
commit 0bfdf598900fd62869659f360d3387ed80eb71cf upstream.
asm/barrier.h is not always included after asm/synch.h, which meant
it was missing __SUBARCH_HAS_LWSYNC, so in some files smp_wmb() would
be eieio when it should be lwsync. kernel/time/hrtimer.c is one case.
__SUBARCH_HAS_LWSYNC is only used in one place, so just fold it in
to where it's used. Previously with my small simulator config, 377
instances of eieio in the tree. After this patch there are 55.
Fixes: 46d075be58 ("powerpc: Optimise smp_wmb")
Cc: stable@vger.kernel.org # v2.6.29+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
95 lines
3.2 KiB
C
95 lines
3.2 KiB
C
/*
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* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
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*/
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#ifndef _ASM_POWERPC_BARRIER_H
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#define _ASM_POWERPC_BARRIER_H
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/*
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* Memory barrier.
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* The sync instruction guarantees that all memory accesses initiated
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* by this processor have been performed (with respect to all other
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* mechanisms that access memory). The eieio instruction is a barrier
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* providing an ordering (separately) for (a) cacheable stores and (b)
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* loads and stores to non-cacheable memory (e.g. I/O devices).
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*
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* mb() prevents loads and stores being reordered across this point.
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* rmb() prevents loads being reordered across this point.
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* wmb() prevents stores being reordered across this point.
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* read_barrier_depends() prevents data-dependent loads being reordered
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* across this point (nop on PPC).
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*
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* *mb() variants without smp_ prefix must order all types of memory
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* operations with one another. sync is the only instruction sufficient
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* to do this.
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*
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* For the smp_ barriers, ordering is for cacheable memory operations
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* only. We have to use the sync instruction for smp_mb(), since lwsync
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* doesn't order loads with respect to previous stores. Lwsync can be
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* used for smp_rmb() and smp_wmb().
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*
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* However, on CPUs that don't support lwsync, lwsync actually maps to a
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* heavy-weight sync, so smp_wmb() can be a lighter-weight eieio.
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*/
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#define mb() __asm__ __volatile__ ("sync" : : : "memory")
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#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
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#define wmb() __asm__ __volatile__ ("sync" : : : "memory")
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#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } while (0)
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/* The sub-arch has lwsync */
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#if defined(__powerpc64__) || defined(CONFIG_PPC_E500MC)
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# define SMPWMB LWSYNC
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#else
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# define SMPWMB eieio
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#endif
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#define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
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#define dma_rmb() __lwsync()
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#define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
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#ifdef CONFIG_SMP
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#define smp_lwsync() __lwsync()
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#define smp_mb() mb()
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#define smp_rmb() __lwsync()
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#define smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
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#else
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#define smp_lwsync() barrier()
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#define smp_mb() barrier()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#endif /* CONFIG_SMP */
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#define read_barrier_depends() do { } while (0)
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#define smp_read_barrier_depends() do { } while (0)
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/*
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* This is a barrier which prevents following instructions from being
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* started until the value of the argument x is known. For example, if
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* x is a variable loaded from memory, this prevents following
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* instructions from being executed until the load has been performed.
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*/
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#define data_barrier(x) \
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asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory");
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#define smp_store_release(p, v) \
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do { \
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compiletime_assert_atomic_type(*p); \
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smp_lwsync(); \
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WRITE_ONCE(*p, v); \
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} while (0)
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#define smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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compiletime_assert_atomic_type(*p); \
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smp_lwsync(); \
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___p1; \
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})
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#define smp_mb__before_atomic() smp_mb()
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#define smp_mb__after_atomic() smp_mb()
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#define smp_mb__before_spinlock() smp_mb()
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#endif /* _ASM_POWERPC_BARRIER_H */
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