Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754292AbaFWNEU (ORCPT ); Mon, 23 Jun 2014 09:04:20 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36897 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754249AbaFWNEQ (ORCPT ); Mon, 23 Jun 2014 09:04:16 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Rabin Vincent , Russell King , Luis Henriques Subject: [PATCH 3.11 35/93] ARM: 8064/1: fix v7-M signal return Date: Mon, 23 Jun 2014 14:02:14 +0100 Message-Id: <1403528592-2163-36-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1403528592-2163-1-git-send-email-luis.henriques@canonical.com> References: <1403528592-2163-1-git-send-email-luis.henriques@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Rabin Vincent commit 483a6c9d447f625b991fa04a1530493d893984db upstream. According to the ARM ARM, the behaviour is UNPREDICTABLE if the PC read from the exception return stack is not half word aligned. See the pseudo code for ExceptionReturn() and PopStack(). The signal handler's address has the bit 0 set, and setup_return() directly writes this to regs->ARM_pc. Current hardware happens to discard this bit, but QEMU's emulation doesn't and this makes processes crash. Mask out bit 0 before the exception return in order to get predictable behaviour. Fixes: 19c4d593f0b4 ("ARM: ARMv7-M: Add support for exception handling") Acked-by: Uwe Kleine-König Signed-off-by: Rabin Vincent Signed-off-by: Russell King Signed-off-by: Luis Henriques --- arch/arm/kernel/entry-header.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index de23a9beed13..b527a79f73f1 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -132,6 +132,10 @@ orrne r5, V7M_xPSR_FRAMEPTRALIGN biceq r5, V7M_xPSR_FRAMEPTRALIGN + @ ensure bit 0 is cleared in the PC, otherwise behaviour is + @ unpredictable + bic r4, #1 + @ write basic exception frame stmdb r2!, {r1, r3-r5} ldmia sp, {r1, r3-r5} -- 1.9.1 -- 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/