From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267278AbUI0TNO (ORCPT ); Mon, 27 Sep 2004 15:13:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267263AbUI0TMz (ORCPT ); Mon, 27 Sep 2004 15:12:55 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:38325 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S267251AbUI0TLf (ORCPT ); Mon, 27 Sep 2004 15:11:35 -0400 Date: Mon, 27 Sep 2004 12:10:58 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: akpm@osdl.org cc: Andy Lutomirski , ak@suse.de, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org Subject: page fault scalability patch V9: [4/7] generally available cmpxchg on i386 In-Reply-To: Message-ID: References: <20040920205752.GH4242@wotan.suse.de> <200409211841.25507.vda@port.imtp.ilyichevsk.odessa.ua> <20040921154542.GB12132@wotan.suse.de> <41527885.8020402@myrealbox.com> <20040923090345.GA6146@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Changelog * Make cmpxchg and cmpxchg8b generally available on i386. * Provide emulation of cmpxchg suitable for UP if build and run on 386. * Provide emulation of cmpxchg8b suitable for UP if build and run on 386 or 486. Signed-off-by: Christoph Lameter Index: linux-2.6.9-rc2/include/asm-i386/system.h =================================================================== --- linux-2.6.9-rc2.orig/include/asm-i386/system.h 2004-09-12 22:31:26.000000000 -0700 +++ linux-2.6.9-rc2/include/asm-i386/system.h 2004-09-21 13:37:06.000000000 -0700 @@ -240,7 +240,24 @@ */ #ifdef CONFIG_X86_CMPXCHG + #define __HAVE_ARCH_CMPXCHG 1 +#define cmpxchg(ptr,o,n)\ + ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\ + (unsigned long)(n),sizeof(*(ptr)))) + +#else + +/* + * Building a kernel capable running on 80386. It may be necessary to + * simulate the cmpxchg on the 80386 CPU. + */ + +extern unsigned long cmpxchg_386(void *, unsigned long, unsigned long); + +#define cmpxchg(ptr,o,n)\ + ((__typeof__(*(ptr)))cmpxchg_386((ptr),(unsigned long)(o),\ + (unsigned long)(n),sizeof(*(ptr)))) #endif static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, @@ -270,10 +287,32 @@ return old; } -#define cmpxchg(ptr,o,n)\ - ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\ - (unsigned long)(n),sizeof(*(ptr)))) - +static inline unsigned long long __cmpxchg8b(volatile unsigned long long *ptr, + unsigned long long old, unsigned long long newv) +{ + unsigned long long prev; + __asm__ __volatile__( + LOCK_PREFIX "cmpxchg8b %4\n" + : "=A" (prev) + : "0" (old), "c" ((unsigned long)(newv >> 32)), + "b" ((unsigned long)(newv & 0xffffffffLL)), "m" (ptr) + : "memory"); + return prev ; +} + +#ifdef CONFIG_X86_CMPXCHG8B +#define cmpxchg8b __cmpxchg8b +#else +/* + * Building a kernel capable of running on 80486 and 80386. Both + * do not support cmpxchg8b. Call a function that emulates the + * instruction if necessary. + */ +extern unsigned long long cmpxchg_486(unsigned long long *, + unsigned long long, unsigned long long); +#define cmpxchg8b cmpxchg8b_486 +#endif + #ifdef __KERNEL__ struct alt_instr { __u8 *instr; /* original instruction */ Index: linux-2.6.9-rc2/arch/i386/Kconfig =================================================================== --- linux-2.6.9-rc2.orig/arch/i386/Kconfig 2004-09-21 13:12:25.000000000 -0700 +++ linux-2.6.9-rc2/arch/i386/Kconfig 2004-09-21 13:32:25.000000000 -0700 @@ -345,6 +345,11 @@ depends on !M386 default y +config X86_CMPXCHG8B + bool + depends on !M386 && !M486 + default y + config X86_XADD bool depends on !M386 Index: linux-2.6.9-rc2/arch/i386/kernel/cpu/intel.c =================================================================== --- linux-2.6.9-rc2.orig/arch/i386/kernel/cpu/intel.c 2004-09-12 22:31:59.000000000 -0700 +++ linux-2.6.9-rc2/arch/i386/kernel/cpu/intel.c 2004-09-21 13:32:25.000000000 -0700 @@ -415,5 +415,65 @@ return 0; } +#ifndef CONFIG_X86_CMPXCHG +unsigned long cmpxchg_386(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + unsigned long prev; + unsigned long flags; + /* + * Check if the kernel was compiled for an old cpu but the + * currently running cpu can do cmpxchg after all + * All CPUs except 386 support CMPXCHG + */ + if (cpu_data->x86 > 3) return __cmpxchg(ptr, old, new, size); + + /* Poor man's cmpxchg for 386. Unsuitable for SMP */ + local_irq_save(flags); + switch (size) { + case 1: + prev = * (u8 *)ptr; + if (prev == old) *(u8 *)ptr = new; + break; + case 2: + prev = * (u16 *)ptr; + if (prev == old) *(u16 *)ptr = new; + case 4: + prev = *(u32 *)ptr; + if (prev == old) *(u32 *)ptr = new; + break; + } + local_irq_restore(flags); + return prev; +} + +EXPORT_SYMBOL(cmpxchg_386); +#endif + +#ifndef CONFIG_X86_CMPXCHG8B +unsigned long long cmpxchg8b_486(unsigned long long *ptr, + unsigned long long old, unsigned long long newv) +{ + unsigned long long prev; + unsigned long flags; + + /* + * Check if the kernel was compiled for an old cpu but + * we are running really on a cpu capable of cmpxchg8b + */ + + if (cpu_has(cpu_data, X86_FEATURE_CX8)) return __cmpxchg8b(ptr, old newv); + + /* Poor mans cmpxchg8b for 386 and 486. Not suitable for SMP */ + local_irq_save(flags); + prev = *ptr; + if (prev == old) *ptr = newv; + local_irq_restore(flags); + return prev; +} + +EXPORT_SYMBOL(cmpxchg8b_486); +#endif + // arch_initcall(intel_cpu_init);