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[Xen-changelog] [xen-4.0-testing] x86: Fix atomic_write*() macros to cor

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Subject: [Xen-changelog] [xen-4.0-testing] x86: Fix atomic_write*() macros to correctly inform GCC that memory
From: "Xen patchbot-4.0-testing" <patchbot-4.0-testing@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 17 Jan 2011 07:52:22 -0800
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# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1294483522 0
# Node ID ed6ff865366e8dc9964a6dd0050f831300881a93
# Parent  ee9d0e23fff739facc9d4c528e3fe38802f656c7
x86: Fix atomic_write*() macros to correctly inform GCC that memory
it knows about is being written to.

The bug is a copy-and-paste error from inline asm that writes to I/O
memory. In that case, as with asm for accessign guest memory,
specifying memory as a read-only parameter is acceptable because the
memory cannot alias with anything that GCC reads directly.

Signed-off-by: Keir Fraser <keir@xxxxxxx>
xen-unstable changeset:   22683:533d6e5c0099
xen-unstable date:        Sat Jan 08 10:05:55 2011 +0000
 xen/include/asm-x86/atomic.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff -r ee9d0e23fff7 -r ed6ff865366e xen/include/asm-x86/atomic.h
--- a/xen/include/asm-x86/atomic.h      Fri Jan 07 13:32:36 2011 +0000
+++ b/xen/include/asm-x86/atomic.h      Sat Jan 08 10:45:22 2011 +0000
@@ -17,8 +17,8 @@ static inline type name(const volatile t
 #define build_atomic_write(name, size, type, reg, barrier) \
 static inline void name(volatile type *addr, type val) \
-{ asm volatile("mov" size " %0,%1": :reg (val), \
-"m" (*(volatile type *)addr) barrier); }
+{ asm volatile("mov" size " %1,%0": "=m" (*(volatile type *)addr) \
+:reg (val) barrier); }
 build_atomic_read(atomic_read8, "b", uint8_t, "=q", )
 build_atomic_read(atomic_read16, "w", uint16_t, "=r", )

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