From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756043Ab1I1WvL (ORCPT ); Wed, 28 Sep 2011 18:51:11 -0400 Received: from cantor2.suse.de ([195.135.220.15]:55097 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933594Ab1I1Wu7 (ORCPT ); Wed, 28 Sep 2011 18:50:59 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Sep 28 15:01:48 2011 Message-Id: <20110928220148.884066566@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 28 Sep 2011 15:03:07 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Will Deacon , Russell King Subject: [223/244] ARM: 7099/1: futex: preserve oldval in SMP __futex_atomic_op In-Reply-To: <20110928220225.GA27128@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let us know. ------------------ From: Will Deacon commit df77abcafc8dc881b6c9347548651777088e4b27 upstream. The SMP implementation of __futex_atomic_op clobbers oldval with the status flag from the exclusive store. This causes it to always read as zero when performing the FUTEX_OP_CMP_* operation. This patch updates the ARM __futex_atomic_op implementations to take a tmp argument, allowing us to store the strex status flag without overwriting the register containing oldval. Reported-by: Minho Ban Reviewed-by: Nicolas Pitre Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/futex.h | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -25,17 +25,17 @@ #ifdef CONFIG_SMP -#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ smp_mb(); \ __asm__ __volatile__( \ - "1: ldrex %1, [%2]\n" \ + "1: ldrex %1, [%3]\n" \ " " insn "\n" \ - "2: strex %1, %0, [%2]\n" \ - " teq %1, #0\n" \ + "2: strex %2, %0, [%3]\n" \ + " teq %2, #0\n" \ " bne 1b\n" \ " mov %0, #0\n" \ - __futex_atomic_ex_table("%4") \ - : "=&r" (ret), "=&r" (oldval) \ + __futex_atomic_ex_table("%5") \ + : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ : "cc", "memory") @@ -73,14 +73,14 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, #include #include -#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ __asm__ __volatile__( \ - "1: " T(ldr) " %1, [%2]\n" \ + "1: " T(ldr) " %1, [%3]\n" \ " " insn "\n" \ - "2: " T(str) " %0, [%2]\n" \ + "2: " T(str) " %0, [%3]\n" \ " mov %0, #0\n" \ - __futex_atomic_ex_table("%4") \ - : "=&r" (ret), "=&r" (oldval) \ + __futex_atomic_ex_table("%5") \ + : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ : "cc", "memory") @@ -117,7 +117,7 @@ futex_atomic_op_inuser (int encoded_op, int cmp = (encoded_op >> 24) & 15; int oparg = (encoded_op << 8) >> 20; int cmparg = (encoded_op << 20) >> 20; - int oldval = 0, ret; + int oldval = 0, ret, tmp; if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) oparg = 1 << oparg; @@ -129,19 +129,19 @@ futex_atomic_op_inuser (int encoded_op, switch (op) { case FUTEX_OP_SET: - __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_OR: - __futex_atomic_op("orr %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_ANDN: - __futex_atomic_op("and %0, %1, %3", ret, oldval, uaddr, ~oparg); + __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg); break; case FUTEX_OP_XOR: - __futex_atomic_op("eor %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; default: ret = -ENOSYS;