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authorH. Peter Anvin <hpa@zytor.com>2010-07-27 17:01:49 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-13 13:30:39 -0700
commit568132624386f53e87575195d868db9afb2e9316 (patch)
tree91bb3d419427268e4ec90273fef60fc13cfa95ed /arch
parent203824bea46cc2d9809833e77dd39780d5bcb20c (diff)
downloadlinux-linaro-568132624386f53e87575195d868db9afb2e9316.tar.gz
x86: Add memory modify constraints to xchg() and cmpxchg()
commit 113fc5a6e8c2288619ff7e8187a6f556b7e0d372 upstream. xchg() and cmpxchg() modify their memory operands, not merely read them. For some versions of gcc the "memory" clobber has apparently dealt with the situation, but not for all. Originally-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Glauber Costa <glommer@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: Peter Palfrader <peter@palfrader.org> Cc: Greg KH <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Zachary Amsden <zamsden@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> LKML-Reference: <4C4F7277.8050306@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/cmpxchg_32.h68
-rw-r--r--arch/x86/include/asm/cmpxchg_64.h40
2 files changed, 54 insertions, 54 deletions
diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index 8859e12dd3c..c1cf59d72f0 100644
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -27,20 +27,20 @@ struct __xchg_dummy {
switch (size) { \
case 1: \
asm volatile("xchgb %b0,%1" \
- : "=q" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=q" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
case 2: \
asm volatile("xchgw %w0,%1" \
- : "=r" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=r" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
case 4: \
asm volatile("xchgl %0,%1" \
- : "=r" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=r" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
default: \
@@ -70,14 +70,14 @@ static inline void __set_64bit(unsigned long long *ptr,
unsigned int low, unsigned int high)
{
asm volatile("\n1:\t"
- "movl (%0), %%eax\n\t"
- "movl 4(%0), %%edx\n\t"
- LOCK_PREFIX "cmpxchg8b (%0)\n\t"
+ "movl (%1), %%eax\n\t"
+ "movl 4(%1), %%edx\n\t"
+ LOCK_PREFIX "cmpxchg8b (%1)\n\t"
"jnz 1b"
- : /* no outputs */
- : "D"(ptr),
- "b"(low),
- "c"(high)
+ : "=m" (*ptr)
+ : "D" (ptr),
+ "b" (low),
+ "c" (high)
: "ax", "dx", "memory");
}
@@ -121,21 +121,21 @@ extern void __cmpxchg_wrong_size(void);
__typeof__(*(ptr)) __new = (new); \
switch (size) { \
case 1: \
- asm volatile(lock "cmpxchgb %b1,%2" \
- : "=a"(__ret) \
- : "q"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgb %b2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "q" (__new), "0" (__old) \
: "memory"); \
break; \
case 2: \
- asm volatile(lock "cmpxchgw %w1,%2" \
- : "=a"(__ret) \
- : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgw %w2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "r" (__new), "0" (__old) \
: "memory"); \
break; \
case 4: \
- asm volatile(lock "cmpxchgl %1,%2" \
- : "=a"(__ret) \
- : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgl %2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "r" (__new), "0" (__old) \
: "memory"); \
break; \
default: \
@@ -180,12 +180,12 @@ static inline unsigned long long __cmpxchg64(volatile void *ptr,
unsigned long long new)
{
unsigned long long prev;
- asm volatile(LOCK_PREFIX "cmpxchg8b %3"
- : "=A"(prev)
- : "b"((unsigned long)new),
- "c"((unsigned long)(new >> 32)),
- "m"(*__xg(ptr)),
- "0"(old)
+ asm volatile(LOCK_PREFIX "cmpxchg8b %1"
+ : "=A" (prev),
+ "+m" (*__xg(ptr))
+ : "b" ((unsigned long)new),
+ "c" ((unsigned long)(new >> 32)),
+ "0" (old)
: "memory");
return prev;
}
@@ -195,12 +195,12 @@ static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
unsigned long long new)
{
unsigned long long prev;
- asm volatile("cmpxchg8b %3"
- : "=A"(prev)
- : "b"((unsigned long)new),
- "c"((unsigned long)(new >> 32)),
- "m"(*__xg(ptr)),
- "0"(old)
+ asm volatile("cmpxchg8b %1"
+ : "=A" (prev),
+ "+m" (*__xg(ptr))
+ : "b" ((unsigned long)new),
+ "c" ((unsigned long)(new >> 32)),
+ "0" (old)
: "memory");
return prev;
}
diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
index 485ae415fae..b92f147339f 100644
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -26,26 +26,26 @@ extern void __cmpxchg_wrong_size(void);
switch (size) { \
case 1: \
asm volatile("xchgb %b0,%1" \
- : "=q" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=q" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
case 2: \
asm volatile("xchgw %w0,%1" \
- : "=r" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=r" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
case 4: \
asm volatile("xchgl %k0,%1" \
- : "=r" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=r" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
case 8: \
asm volatile("xchgq %0,%1" \
- : "=r" (__x) \
- : "m" (*__xg(ptr)), "0" (__x) \
+ : "=r" (__x), "+m" (*__xg(ptr)) \
+ : "0" (__x) \
: "memory"); \
break; \
default: \
@@ -71,27 +71,27 @@ extern void __cmpxchg_wrong_size(void);
__typeof__(*(ptr)) __new = (new); \
switch (size) { \
case 1: \
- asm volatile(lock "cmpxchgb %b1,%2" \
- : "=a"(__ret) \
- : "q"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgb %b2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "q" (__new), "0" (__old) \
: "memory"); \
break; \
case 2: \
- asm volatile(lock "cmpxchgw %w1,%2" \
- : "=a"(__ret) \
- : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgw %w2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "r" (__new), "0" (__old) \
: "memory"); \
break; \
case 4: \
- asm volatile(lock "cmpxchgl %k1,%2" \
- : "=a"(__ret) \
- : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgl %k2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "r" (__new), "0" (__old) \
: "memory"); \
break; \
case 8: \
- asm volatile(lock "cmpxchgq %1,%2" \
- : "=a"(__ret) \
- : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \
+ asm volatile(lock "cmpxchgq %2,%1" \
+ : "=a" (__ret), "+m" (*__xg(ptr)) \
+ : "r" (__new), "0" (__old) \
: "memory"); \
break; \
default: \