From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753644AbYAVUU2 (ORCPT ); Tue, 22 Jan 2008 15:20:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752012AbYAVUUT (ORCPT ); Tue, 22 Jan 2008 15:20:19 -0500 Received: from mx1.redhat.com ([66.187.233.31]:43667 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751820AbYAVUUS (ORCPT ); Tue, 22 Jan 2008 15:20:18 -0500 Message-ID: <47964FD5.6020801@redhat.com> Date: Tue, 22 Jan 2008 15:19:33 -0500 From: Chuck Ebbert Organization: Red Hat User-Agent: Thunderbird 1.5.0.12 (X11/20071019) MIME-Version: 1.0 To: Thomas Gleixner CC: Andi Kleen , Andrew Morton , Linus Torvalds , Stable Team , linux-kernel , Ingo Molnar , Gerd Hoffmann Subject: Re: The SMP alternatives code breaks exception fixup? References: <479504F6.4080005@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/22/2008 07:35 AM, Thomas Gleixner wrote: > > That's a long standing bug in both the PI futex and the standard futex > code. Needs to go to stable as well. > Here's the 2.6.23 version: Subject: x86: fix missing exception entry for SMP alternatives in futex macros From: Thomas Gleixner The exception fixup for the futex macros __futex_atomic_op2 and futex_atomic_cmpxchg_inatomic() is missing an entry when the lock prefix is replaced by a NOP via SMP alternatives. Chuck Ebert tracked this down from the information provided in: https://bugzilla.redhat.com/show_bug.cgi?id=429412 The solution is to add another fixup after the LOCK_PREFIX, so both the LOCK and NOP case have their own entry in the exception table. The solution was pointed out by Andi Kleen. Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar --- include/asm-i386/futex.h | 8 ++++---- include/asm-x86_64/futex.h | 8 ++++---- 2 files changed, 8 insertions(+), 8 deletions(-) Index: linux-2.6/include/asm-i386/futex.h =================================================================== --- linux-2.6.orig/include/asm-i386/futex.h 2008-01-22 13:13:10.000000000 +0100 +++ linux-2.6/include/asm-i386/futex.h 2008-01-22 13:13:49.000000000 +0100 @@ -28,7 +28,7 @@ "1: movl %2, %0\n\ movl %0, %3\n" \ insn "\n" \ -"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\ +"2: " LOCK_PREFIX "\n 5: cmpxchgl %3, %2\n\ jnz 1b\n\ 3: .section .fixup,\"ax\"\n\ 4: mov %5, %1\n\ @@ -36,7 +36,7 @@ .previous\n\ .section __ex_table,\"a\"\n\ .align 8\n\ - .long 1b,4b,2b,4b\n\ + .long 1b,4b,2b,4b,5b,4b\n\ .previous" \ : "=&a" (oldval), "=&r" (ret), "+m" (*uaddr), \ "=&r" (tem) \ @@ -111,7 +111,7 @@ futex_atomic_cmpxchg_inatomic(int __user return -EFAULT; __asm__ __volatile__( - "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n" + "1: " LOCK_PREFIX "\n 4: cmpxchgl %3, %1 \n" "2: .section .fixup, \"ax\" \n" "3: mov %2, %0 \n" @@ -120,7 +120,7 @@ futex_atomic_cmpxchg_inatomic(int __user " .section __ex_table, \"a\" \n" " .align 8 \n" - " .long 1b,3b \n" + " .long 1b,3b,4b,3b \n" " .previous \n" : "=a" (oldval), "+m" (*uaddr) Index: linux-2.6/include/asm-x86_64/futex.h =================================================================== --- linux-2.6.orig/include/asm-x86_64/futex.h 2008-01-22 13:13:10.000000000 +0100 +++ linux-2.6/include/asm-x86_64/futex.h 2008-01-22 13:13:49.000000000 +0100 @@ -27,7 +27,7 @@ "1: movl %2, %0\n\ movl %0, %3\n" \ insn "\n" \ -"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\ +"2: " LOCK_PREFIX "\n 5: cmpxchgl %3, %2\n\ jnz 1b\n\ 3: .section .fixup,\"ax\"\n\ 4: mov %5, %1\n\ @@ -35,7 +35,7 @@ .previous\n\ .section __ex_table,\"a\"\n\ .align 8\n\ - .quad 1b,4b,2b,4b\n\ + .quad 1b,4b,2b,4b,5b,4b\n\ .previous" \ : "=&a" (oldval), "=&r" (ret), "=m" (*uaddr), \ "=&r" (tem) \ @@ -101,7 +101,7 @@ futex_atomic_cmpxchg_inatomic(int __user return -EFAULT; __asm__ __volatile__( - "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n" + "1: " LOCK_PREFIX "\n 4: cmpxchgl %3, %1 \n" "2: .section .fixup, \"ax\" \n" "3: mov %2, %0 \n" @@ -110,7 +110,7 @@ futex_atomic_cmpxchg_inatomic(int __user " .section __ex_table, \"a\" \n" " .align 8 \n" - " .quad 1b,3b \n" + " .quad 1b,3b,4b,3b \n" " .previous \n" : "=a" (oldval), "=m" (*uaddr)