From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 233F7900091 for ; Fri, 15 Apr 2011 16:13:03 -0400 (EDT) Message-Id: <20110415201300.189983463@linux.com> Date: Fri, 15 Apr 2011 15:12:55 -0500 From: Christoph Lameter Subject: [slubllv333num@/21] x86: Add support for cmpxchg_double References: <20110415201246.096634892@linux.com> Content-Disposition: inline; filename=cmpxchg_double_x86 Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: David Rientjes , Hugh Dickins , Eric Dumazet , "H. Peter Anvin" , Mathieu Desnoyers , linux-mm@kvack.org A simple implementation that only supports the word size and does not have a fallback mode (would require a spinlock). And 32 and 64 bit support for cmpxchg_double. cmpxchg double uses the cmpxchg8b or cmpxchg16b instruction on x86 processors to compare and swap 2 machine words. This allows lockless algorithms to move more context information through critical sections. Set a flag CONFIG_CMPXCHG_DOUBLE to signal the support of that feature during kernel builds. Signed-off-by: Christoph Lameter --- arch/x86/Kconfig.cpu | 3 ++ arch/x86/include/asm/cmpxchg_32.h | 46 ++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/cmpxchg_64.h | 45 +++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/cpufeature.h | 1 4 files changed, 95 insertions(+) Index: linux-2.6/arch/x86/include/asm/cmpxchg_64.h =================================================================== --- linux-2.6.orig/arch/x86/include/asm/cmpxchg_64.h 2011-04-13 15:19:53.000000000 -0500 +++ linux-2.6/arch/x86/include/asm/cmpxchg_64.h 2011-04-15 13:14:45.000000000 -0500 @@ -151,4 +151,49 @@ extern void __cmpxchg_wrong_size(void); cmpxchg_local((ptr), (o), (n)); \ }) +#define cmpxchg16b(ptr, o1, o2, n1, n2) \ +({ \ + char __ret; \ + __typeof__(o2) __junk; \ + __typeof__(*(ptr)) __old1 = (o1); \ + __typeof__(o2) __old2 = (o2); \ + __typeof__(*(ptr)) __new1 = (n1); \ + __typeof__(o2) __new2 = (n2); \ + asm volatile(LOCK_PREFIX_HERE "lock; cmpxchg16b (%%rsi);setz %1" \ + : "=d"(__junk), "=a"(__ret) \ + : "S"(ptr), "b"(__new1), "c"(__new2), \ + "a"(__old1), "d"(__old2)); \ + __ret; }) + + +#define cmpxchg16b_local(ptr, o1, o2, n1, n2) \ +({ \ + char __ret; \ + __typeof__(o2) __junk; \ + __typeof__(*(ptr)) __old1 = (o1); \ + __typeof__(o2) __old2 = (o2); \ + __typeof__(*(ptr)) __new1 = (n1); \ + __typeof__(o2) __new2 = (n2); \ + asm volatile("cmpxchg16b (%%rsi)\n\t\tsetz %1\n\t" \ + : "=d"(__junk)_, "=a"(__ret) \ + : "S"((ptr)), "b"(__new1), "c"(__new2), \ + "a"(__old1), "d"(__old2)); \ + __ret; }) + +#define cmpxchg_double(ptr, o1, o2, n1, n2) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + VM_BUG_ON((unsigned long)(ptr) % 16); \ + cmpxchg16b((ptr), (o1), (o2), (n1), (n2)); \ +}) + +#define cmpxchg_double_local(ptr, o1, o2, n1, n2) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ + VM_BUG_ON((unsigned long)(ptr) % 16); \ + cmpxchg16b_local((ptr), (o1), (o2), (n1), (n2)); \ +}) + +#define system_has_cmpxchg_double() cpu_has_cx16 + #endif /* _ASM_X86_CMPXCHG_64_H */ Index: linux-2.6/arch/x86/include/asm/cmpxchg_32.h =================================================================== --- linux-2.6.orig/arch/x86/include/asm/cmpxchg_32.h 2011-04-13 15:19:53.000000000 -0500 +++ linux-2.6/arch/x86/include/asm/cmpxchg_32.h 2011-04-15 13:14:45.000000000 -0500 @@ -280,4 +280,50 @@ static inline unsigned long cmpxchg_386( #endif +#define cmpxchg8b(ptr, o1, o2, n1, n2) \ +({ \ + char __ret; \ + __typeof__(o2) __dummy; \ + __typeof__(*(ptr)) __old1 = (o1); \ + __typeof__(o2) __old2 = (o2); \ + __typeof__(*(ptr)) __new1 = (n1); \ + __typeof__(o2) __new2 = (n2); \ + asm volatile(LOCK_PREFIX_HERE "lock; cmpxchg8b (%%esi); setz %1"\ + : "d="(__dummy), "=a" (__ret) \ + : "S" ((ptr)), "a" (__old1), "d"(__old2), \ + "b" (__new1), "c" (__new2) \ + : "memory"); \ + __ret; }) + + +#define cmpxchg8b_local(ptr, o1, o2, n1, n2) \ +({ \ + char __ret; \ + __typeof__(o2) __dummy; \ + __typeof__(*(ptr)) __old1 = (o1); \ + __typeof__(o2) __old2 = (o2); \ + __typeof__(*(ptr)) __new1 = (n1); \ + __typeof__(o2) __new2 = (n2); \ + asm volatile("cmpxchg8b (%%esi); tsetz %1" \ + : "d="(__dummy), "=a"(__ret) \ + : "S" ((ptr)), "a" (__old), "d"(__old2), \ + "b" (__new1), "c" (__new2), \ + : "memory"); \ + __ret; }) + + +#define cmpxchg_double(ptr, o1, o2, n1, n2) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + VM_BUG_ON((unsigned long)(ptr) % 8); \ + cmpxchg8b((ptr), (o1), (o2), (n1), (n2)); \ +}) + +#define cmpxchg_double_local(ptr, o1, o2, n1, n2) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + VM_BUG_ON((unsigned long)(ptr) % 8); \ + cmpxchg16b_local((ptr), (o1), (o2), (n1), (n2)); \ +}) + #endif /* _ASM_X86_CMPXCHG_32_H */ Index: linux-2.6/arch/x86/Kconfig.cpu =================================================================== --- linux-2.6.orig/arch/x86/Kconfig.cpu 2011-04-13 15:19:53.000000000 -0500 +++ linux-2.6/arch/x86/Kconfig.cpu 2011-04-15 13:14:45.000000000 -0500 @@ -308,6 +308,9 @@ config X86_CMPXCHG config CMPXCHG_LOCAL def_bool X86_64 || (X86_32 && !M386) +config CMPXCHG_DOUBLE + def_bool X86_64 || (X86_32 && !M386) + config X86_L1_CACHE_SHIFT int default "7" if MPENTIUM4 || MPSC Index: linux-2.6/arch/x86/include/asm/cpufeature.h =================================================================== --- linux-2.6.orig/arch/x86/include/asm/cpufeature.h 2011-04-15 12:51:51.000000000 -0500 +++ linux-2.6/arch/x86/include/asm/cpufeature.h 2011-04-15 13:14:45.000000000 -0500 @@ -286,6 +286,7 @@ extern const char * const x86_power_flag #define cpu_has_hypervisor boot_cpu_has(X86_FEATURE_HYPERVISOR) #define cpu_has_pclmulqdq boot_cpu_has(X86_FEATURE_PCLMULQDQ) #define cpu_has_perfctr_core boot_cpu_has(X86_FEATURE_PERFCTR_CORE) +#define cpu_has_cx16 boot_cpu_has(X86_FEATURE_CX16) #if defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_64) # define cpu_has_invlpg 1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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