On PowerPC 64bit, the linux-compat mb() definition is implemented with
lwsync instruction, which does not provide Store/Load barrier. Fix this by using "full" sync barrier for mb(). atomic_store_rel() does not need full barrier, change mb() call there to the lwsync instruction if not hitting the known CPU erratas (i.e. on 32bit). Provide powerpc_lwsync() helper to isolate the lwsync/sync compile time selection, and use it in atomic_store_rel() and several other places which duplicate the code. Noted by: alc Reviewed and tested by: nwhitehorn Sponsored by: The FreeBSD Foundation
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=291242
@ -48,7 +48,7 @@
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*/
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#ifdef __powerpc64__
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#define mb() __asm __volatile("lwsync" : : : "memory")
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#define mb() __asm __volatile("sync" : : : "memory")
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#define rmb() __asm __volatile("lwsync" : : : "memory")
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#define wmb() __asm __volatile("lwsync" : : : "memory")
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#define __ATOMIC_REL() __asm __volatile("lwsync" : : : "memory")
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@ -61,6 +61,17 @@
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#define __ATOMIC_ACQ() __asm __volatile("isync" : : : "memory")
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#endif
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static __inline void
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powerpc_lwsync(void)
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{
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#ifdef __powerpc64__
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__asm __volatile("lwsync" : : : "memory");
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#else
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__asm __volatile("sync" : : : "memory");
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#endif
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}
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/*
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* atomic_add(p, v)
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* { *p += v; }
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@ -506,7 +517,8 @@ atomic_load_acq_##TYPE(volatile u_##TYPE *p) \
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static __inline void \
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atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v) \
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{ \
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mb(); \
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\
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powerpc_lwsync(); \
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*p = v; \
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}
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@ -734,34 +746,21 @@ static __inline void
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atomic_thread_fence_acq(void)
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{
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/* See above comment about lwsync being broken on Book-E. */
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#ifdef __powerpc64__
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__asm __volatile("lwsync" : : : "memory");
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#else
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__asm __volatile("sync" : : : "memory");
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#endif
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powerpc_lwsync();
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}
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static __inline void
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atomic_thread_fence_rel(void)
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{
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#ifdef __powerpc64__
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__asm __volatile("lwsync" : : : "memory");
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#else
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__asm __volatile("sync" : : : "memory");
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#endif
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powerpc_lwsync();
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}
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static __inline void
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atomic_thread_fence_acq_rel(void)
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{
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#ifdef __powerpc64__
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__asm __volatile("lwsync" : : : "memory");
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#else
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__asm __volatile("sync" : : : "memory");
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#endif
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powerpc_lwsync();
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}
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static __inline void
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