From 8896fab35e62aa748a5ce62ac773508e51f10be1 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Sun, 30 Oct 2005 14:59:27 -0800 Subject: [PATCH] [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/Kconfig | 5 +++++ include/asm-i386/system.h | 33 ++++++++++++++++++++++++++++++--- 2 files changed, 35 insertions(+), 3 deletions(-) diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 2e3e8dbcb79f..35d3cff30057 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -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 diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index acd5c26b69ba..97d52ac49e46 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -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 { -- 2.20.1