Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752558AbdCAPb6 (ORCPT ); Wed, 1 Mar 2017 10:31:58 -0500 Received: from mailapp01.imgtec.com ([195.59.15.196]:7965 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751106AbdCAPbs (ORCPT ); Wed, 1 Mar 2017 10:31:48 -0500 From: Matt Redfearn To: Ralf Baechle CC: , Matt Redfearn , Marcin Nowakowski , , Paul Burton , Andrew Morton Subject: [PATCH v2 1/5] MIPS: Handle non word sized instructions when examining frame Date: Wed, 1 Mar 2017 14:41:16 +0000 Message-ID: <1488379280-2954-2-git-send-email-matt.redfearn@imgtec.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488379280-2954-1-git-send-email-matt.redfearn@imgtec.com> References: <1488379280-2954-1-git-send-email-matt.redfearn@imgtec.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.150.130.83] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2478 Lines: 65 Commit b6c7a324df37 ("MIPS: Fix get_frame_info() handling of microMIPS function size") goes some way to fixing get_frame_info() to iterate over microMIPS instuctions, but increments the instruction pointer using a postincrement of the instruction pointer, which is of union mips_instruction type. Since the union is sized to the largest member (a word), but microMIPS instructions are a mix of halfword and word sizes, the function does not always iterate correctly, ending up misaligned with the instruction stream and interpreting it incorrectly. Since the instruction modifying the stack pointer is usually the first in the function, that one is usually handled correctly. But the instruction which saves the return address to the sp is some variable number of instructions into the frame and is frequently missed due to not being on a word boundary, leading to incomplete walking of the stack. Fix this by incrementing the instruction pointer based on the size of the previously decoded instruction. Fixes: b6c7a324df37 ("MIPS: Fix get_frame_info() handling of microMIPS function size") Signed-off-by: Matt Redfearn --- Changes in v2: - Keep locals in reverse christmas tree order arch/mips/kernel/process.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 803e255b6fc3..df69ebd361fc 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -346,6 +346,7 @@ static int get_frame_info(struct mips_frame_info *info) bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS); union mips_instruction insn, *ip, *ip_end; const unsigned int max_insns = 128; + unsigned int last_insn_size = 0; unsigned int i; info->pc_offset = -1; @@ -357,15 +358,19 @@ static int get_frame_info(struct mips_frame_info *info) ip_end = (void *)ip + info->func_size; - for (i = 0; i < max_insns && ip < ip_end; i++, ip++) { + for (i = 0; i < max_insns && ip < ip_end; i++) { + ip = (void *)ip + last_insn_size; if (is_mmips && mm_insn_16bit(ip->halfword[0])) { insn.halfword[0] = 0; insn.halfword[1] = ip->halfword[0]; + last_insn_size = sizeof(unsigned short); } else if (is_mmips) { insn.halfword[0] = ip->halfword[1]; insn.halfword[1] = ip->halfword[0]; + last_insn_size = sizeof(unsigned int); } else { insn.word = ip->word; + last_insn_size = sizeof(unsigned int); } if (is_jump_ins(&insn)) -- 2.7.4