Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759538AbZDWHuv (ORCPT ); Thu, 23 Apr 2009 03:50:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757275AbZDWHde (ORCPT ); Thu, 23 Apr 2009 03:33:34 -0400 Received: from sous-sol.org ([216.99.217.87]:50940 "EHLO x200.localdomain" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755314AbZDWHdd (ORCPT ); Thu, 23 Apr 2009 03:33:33 -0400 Message-Id: <20090423072815.477302250@sous-sol.org> User-Agent: quilt/0.47-1 Date: Thu, 23 Apr 2009 00:21:29 -0700 From: Chris Wright To: linux-kernel@vger.kernel.org, stable@kernel.org, jejb@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Paul Mackerras Subject: [patch 069/100] powerpc: Fix data-corrupting bug in __futex_atomic_op References: <20090423072020.428683652@sous-sol.org> Content-Disposition: inline; filename=powerpc-fix-data-corrupting-bug-in-__futex_atomic_op.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2380 Lines: 65 -stable review patch. If anyone has any objections, please let us know. --------------------- From: Paul Mackerras upstream commit: 306a82881b14d950d59e0b59a55093a07d82aa9a Richard Henderson pointed out that the powerpc __futex_atomic_op has a bug: it will write the wrong value if the stwcx. fails and it has to retry the lwarx/stwcx. loop, since 'oparg' will have been overwritten by the result from the first time around the loop. This happens because it uses the same register for 'oparg' (an input) as it uses for the result. This fixes it by using separate registers for 'oparg' and 'ret'. Cc: stable@kernel.org Signed-off-by: Paul Mackerras Signed-off-by: Chris Wright --- arch/powerpc/include/asm/futex.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/arch/powerpc/include/asm/futex.h +++ b/arch/powerpc/include/asm/futex.h @@ -27,7 +27,7 @@ PPC_LONG "1b,4b,2b,4b\n" \ ".previous" \ : "=&r" (oldval), "=&r" (ret) \ - : "b" (uaddr), "i" (-EFAULT), "1" (oparg) \ + : "b" (uaddr), "i" (-EFAULT), "r" (oparg) \ : "cr0", "memory") static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr) @@ -47,19 +47,19 @@ static inline int futex_atomic_op_inuser switch (op) { case FUTEX_OP_SET: - __futex_atomic_op("", ret, oldval, uaddr, oparg); + __futex_atomic_op("mr %1,%4\n", ret, oldval, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op("add %1,%0,%1\n", ret, oldval, uaddr, oparg); + __futex_atomic_op("add %1,%0,%4\n", ret, oldval, uaddr, oparg); break; case FUTEX_OP_OR: - __futex_atomic_op("or %1,%0,%1\n", ret, oldval, uaddr, oparg); + __futex_atomic_op("or %1,%0,%4\n", ret, oldval, uaddr, oparg); break; case FUTEX_OP_ANDN: - __futex_atomic_op("andc %1,%0,%1\n", ret, oldval, uaddr, oparg); + __futex_atomic_op("andc %1,%0,%4\n", ret, oldval, uaddr, oparg); break; case FUTEX_OP_XOR: - __futex_atomic_op("xor %1,%0,%1\n", ret, oldval, uaddr, oparg); + __futex_atomic_op("xor %1,%0,%4\n", ret, oldval, uaddr, oparg); break; default: ret = -ENOSYS; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/