From: "Jan Beulich" <JBeulich@novell.com>
This adjusts i386's cmpxchg patterns so that
- for word and long cmpxchg-es the compiler can utilize all possible
registers
- cmpxchg8b gets disabled when the minimum specified hardware architectur
doesn't support it (like was already happening for the byte, word, and
long ones).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
arch/i386/Kconfig | 5 +++++
include/asm-i386/system.h | 33 ++++++++++++++++++++++++++++++---
2 files changed, 35 insertions(+), 3 deletions(-)
diff -puN arch/i386/Kconfig~x86-cmpxchg-improvements arch/i386/Kconfig
--- devel/arch/i386/Kconfig~x86-cmpxchg-improvements 2005-09-11 23:45:13.000000000 -0700
+++ devel-akpm/arch/i386/Kconfig 2005-09-11 23:45:13.000000000 -0700
@@ -420,6 +420,11 @@ config X86_POPAD_OK
depends on !M386
default y
+config X86_CMPXCHG64
+ bool
+ depends on !M386 && !M486
+ default y
+
config X86_ALIGNMENT_16
bool
depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
diff -puN include/asm-i386/system.h~x86-cmpxchg-improvements include/asm-i386/system.h
--- devel/include/asm-i386/system.h~x86-cmpxchg-improvements 2005-09-11 23:45:13.000000000 -0700
+++ devel-akpm/include/asm-i386/system.h 2005-09-11 23:45:13.000000000 -0700
@@ -167,6 +167,8 @@ struct __xchg_dummy { unsigned long a[10
#define __xg(x) ((struct __xchg_dummy *)(x))
+#ifdef CONFIG_X86_CMPXCHG64
+
/*
* The semantics of XCHGCMP8B are a bit strange, this is why
* there is a loop and the loading of %%eax and %%edx has to
@@ -221,6 +223,8 @@ static inline void __set_64bit_var (unsi
__set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
__set_64bit(ptr, ll_low(value), ll_high(value)) )
+#endif
+
/*
* Note: no "lock" prefix even on SMP: xchg always implies lock anyway
* Note 2: xchg has side effect, so that attribute volatile is necessary,
@@ -259,7 +263,6 @@ static inline unsigned long __xchg(unsig
#ifdef CONFIG_X86_CMPXCHG
#define __HAVE_ARCH_CMPXCHG 1
-#endif
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, int size)
@@ -275,13 +278,13 @@ static inline unsigned long __cmpxchg(vo
case 2:
__asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
: "=a"(prev)
- : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 4:
__asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
: "=a"(prev)
- : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
}
@@ -291,6 +294,30 @@ static inline unsigned long __cmpxchg(vo
#define cmpxchg(ptr,o,n)\
((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
(unsigned long)(n),sizeof(*(ptr))))
+
+#endif
+
+#ifdef CONFIG_X86_CMPXCHG64
+
+static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
+ 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)
+ : "memory");
+ return prev;
+}
+
+#define cmpxchg64(ptr,o,n)\
+ ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
+ (unsigned long long)(n)))
+
+#endif
#ifdef __KERNEL__
struct alt_instr {
_