Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752363AbdFAQkR (ORCPT ); Thu, 1 Jun 2017 12:40:17 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33029 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751876AbdFAPoh (ORCPT ); Thu, 1 Jun 2017 11:44:37 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ralf Baechle" , linux-mips@linux-mips.org, "Paul Burton" , "Leonid Yegoshin" Date: Thu, 01 Jun 2017 16:43:15 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 006/212] MIPS: Clear ISA bit correctly in get_frame_info() In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1919 Lines: 53 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Paul Burton commit ccaf7caf2c73c6db920772bf08bf1d47b2170634 upstream. get_frame_info() can be called in microMIPS kernels with the ISA bit already clear. For example this happens when unwind_stack_by_address() is called because we begin with a PC that has the ISA bit set & subtract the (odd) offset from the preceding symbol (which does not have the ISA bit set). Since get_frame_info() unconditionally subtracts 1 from the PC in microMIPS kernels it incorrectly misaligns the address it then attempts to access code at, leading to an address error exception. Fix this by using msk_isa16_mode() to clear the ISA bit, which allows get_frame_info() to function regardless of whether it is provided with a PC that has the ISA bit set or not. Signed-off-by: Paul Burton Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.") Cc: Leonid Yegoshin Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/14528/ Signed-off-by: Ralf Baechle Signed-off-by: Ben Hutchings --- arch/mips/kernel/process.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -331,17 +331,14 @@ static inline int is_sp_move_ins(union m static int get_frame_info(struct mips_frame_info *info) { -#ifdef CONFIG_CPU_MICROMIPS - union mips_instruction *ip = (void *) (((char *) info->func) - 1); -#else - union mips_instruction *ip = info->func; -#endif + union mips_instruction *ip; unsigned max_insns = info->func_size / sizeof(union mips_instruction); unsigned i; info->pc_offset = -1; info->frame_size = 0; + ip = (void *)msk_isa16_mode((ulong)info->func); if (!ip) goto err;