mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-20 14:16:02 +00:00
[PATCH] x86: cmpxchg improvements
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> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
parent
dacb16b1a0
commit
8896fab35e
2 changed files with 35 additions and 3 deletions
|
@ -424,6 +424,11 @@ 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
|
||||
|
|
|
@ -167,6 +167,8 @@ struct __xchg_dummy { unsigned long a[100]; };
|
|||
#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 (unsigned long long *ptr,
|
|||
__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(unsigned long x, volatile void * ptr, int siz
|
|||
|
||||
#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(volatile void *ptr, unsigned long old,
|
|||
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(volatile void *ptr, unsigned long old,
|
|||
#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 {
|
||||
|
|
Loading…
Reference in a new issue