Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752583AbdHHMZ2 (ORCPT ); Tue, 8 Aug 2017 08:25:28 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:27656 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751880AbdHHMXE (ORCPT ); Tue, 8 Aug 2017 08:23:04 -0400 From: Matt Redfearn To: Ralf Baechle CC: , Matt Redfearn , Marcin Nowakowski , , James Hogan , Ingo Molnar , Paul Burton Subject: [PATCH v3 5/6] MIPS: Stacktrace: Fix microMIPS stack unwinding on big endian systems Date: Tue, 8 Aug 2017 13:22:34 +0100 Message-ID: <1502194955-18018-6-git-send-email-matt.redfearn@imgtec.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1502194955-18018-1-git-send-email-matt.redfearn@imgtec.com> References: <1502194955-18018-1-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: 3684 Lines: 97 The stack unwinding code uses the mips_instuction union to decode the instructions it finds. That union uses the __BITFIELD_FIELD macro to reorder depending on endianness. The stack unwinding code always places 16bit instructions in halfword 1 of the union. This makes the union accesses correct for little endian systems. Similarly, 32bit instructions are reordered such that they are correct for little endian systems. This handling leaves unwinding the stack on big endian systems broken, as the mips_instruction union will then look for the fields in the wrong halfword. To fix this, use a logical shift to place the 16bit instruction into the correct position in the word field of the union. Use the same shifting to order the 2 halfwords of 32bit instuctions. Then replace accesses to the halfword with accesses to the shifted word. In the case of the ADDIUS5 instruction, switch to using the mm16_r5_format union member to avoid the need for a 16bit shift. Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.") Signed-off-by: Matt Redfearn Reviewed-by: James Hogan --- Changes in v3: New patch to fix big endian systems Changes in v2: None arch/mips/kernel/process.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 6fa726b0be01..ba7d5f73c8b0 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -208,7 +208,7 @@ static inline int is_ra_save_ins(union mips_instruction *ip, int *poff) * * microMIPS is way more fun... */ - if (mm_insn_16bit(ip->halfword[1])) { + if (mm_insn_16bit(ip->word >> 16)) { switch (ip->mm16_r5_format.opcode) { case mm_swsp16_op: if (ip->mm16_r5_format.rt != 31) @@ -287,7 +287,7 @@ static inline int is_jump_ins(union mips_instruction *ip) * * microMIPS is kind of more fun... */ - if (mm_insn_16bit(ip->halfword[1])) { + if (mm_insn_16bit(ip->word >> 16)) { if ((ip->mm16_r5_format.opcode == mm_pool16c_op && (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op)) return 1; @@ -324,7 +324,7 @@ static inline int is_sp_move_ins(union mips_instruction *ip) * * microMIPS is not more fun... */ - if (mm_insn_16bit(ip->halfword[1])) { + if (mm_insn_16bit(ip->word >> 16)) { return (ip->mm16_r3_format.opcode == mm_pool16d_op && ip->mm16_r3_format.simmediate & mm_addiusp_func) || (ip->mm16_r5_format.opcode == mm_pool16d_op && @@ -363,12 +363,10 @@ static int get_frame_info(struct mips_frame_info *info) 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]; + insn.word = ip->halfword[0] << 16; last_insn_size = 2; } else if (is_mmips) { - insn.halfword[0] = ip->halfword[1]; - insn.halfword[1] = ip->halfword[0]; + insn.word = ip->halfword[0] << 16 | ip->halfword[1]; last_insn_size = 4; } else { insn.word = ip->word; @@ -382,7 +380,7 @@ static int get_frame_info(struct mips_frame_info *info) if (is_sp_move_ins(&insn)) { #ifdef CONFIG_CPU_MICROMIPS - if (mm_insn_16bit(ip->halfword[0])) + if (mm_insn_16bit(insn.word >> 16)) { unsigned short tmp; @@ -395,7 +393,7 @@ static int get_frame_info(struct mips_frame_info *info) tmp ^= 0x100; info->frame_size = -(signed short)(tmp << 2); } else { - tmp = (ip->halfword[0] >> 1); + tmp = (ip->mm16_r5_format.imm >> 1); info->frame_size = -(signed short)(tmp & 0xf); } } else -- 2.7.4