From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 09 May 2013 16:48:23 +0200 (CEST) Received: from mail-pa0-f50.google.com ([209.85.220.50]:39202 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6824769Ab3EIOsOXL6wS (ORCPT ); Thu, 9 May 2013 16:48:14 +0200 Received: by mail-pa0-f50.google.com with SMTP id fb10so2145888pad.23 for ; Thu, 09 May 2013 07:48:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:date:from:to:subject:message-id:mime-version :content-type:content-disposition:user-agent; bh=4wocrIPDSxNbfSIDpjqo1TpUfg5qobs+70dXgUdqTlI=; b=mi+BsVjpsHlfaUuOtbA6CEkEcdFv+a6LVuW91MulrmtHut5QSnkViUmxFYkQVZOvEU ffC6TpbhUJQhvLfEa8Ocmh2E5FtEyD5lcZj2ct9EubL1ygbow5sqQXxZ7f6RgxItvMTs xaaq4LuX9zUbY7u+zWNAKdfNhDnBfer8mKyG4nQiJzp7mRAPk0YQBlAYcWpj5uIzU9wt 3q1sQJCOi3iF24cOst2MBnmgdPmmMOrG0f6u9D4FNPR4xwKbrwWAOxm+150TS1yaugYV 2Ni96Z8j9OWdGy6qvZWuAj8DtRgsvaLyi4pMYbX65Rz/sXfjXAQlh4pYcrrjulYgZjui IkIg== X-Received: by 10.66.122.163 with SMTP id lt3mr3788018pab.219.1368110887601; Thu, 09 May 2013 07:48:07 -0700 (PDT) Received: from hades (114-25-190-57.dynamic.hinet.net. [114.25.190.57]) by mx.google.com with ESMTPSA id uv1sm3348755pbc.16.2013.05.09.07.48.02 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 09 May 2013 07:48:06 -0700 (PDT) Date: Thu, 9 May 2013 22:47:53 +0800 From: Tony Wu To: ralf@linux-mips.org, linux-mips@linux-mips.org Subject: [PATCH 1/2] MIPS: detect sibling call in get_frame_info Message-ID: <20130509144753.GC3562@hades> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 36365 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: tung7970@gmail.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips Given a function, get_frame_info() analyzes its instructions to figure out frame size and return address. get_frame_info() works as follows: 1. analyze up to 128 instructions if the function size is unknown 2. search for 'addiu/daddiu sp,sp,-immed' for frame size 3. search for 'sw ra,offset(sp)' for return address 4. end search when it sees jr/jal/jalr This leads to an issue when the given function is a sibling call, example given as follows. 801ca110 : 801ca110: 8f820000 lw v0,0(gp) 801ca114: 8c420000 lw v0,0(v0) 801ca118: 080726f0 j 801c9bc0 <__schedule> 801ca11c: 00000000 nop 801ca120 : 801ca120: 27bdffe8 addiu sp,sp,-24 801ca124: 3c028022 lui v0,0x8022 801ca128: afbf0014 sw ra,20(sp) In this case, get_frame_info() cannot properly detect schedule's frame info, and eventually returns io_schedule's info instead. This patch adds sibling call check by detecting out of range jump. Signed-off-by: Tony Wu --- arch/mips/kernel/process.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index cfc742d..a794eb5 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -223,6 +223,9 @@ struct mips_frame_info { int pc_offset; }; +#define J_TARGET(pc,target) \ + (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) + static inline int is_ra_save_ins(union mips_instruction *ip) { /* sw / sd $ra, offset($sp) */ @@ -250,11 +253,25 @@ static inline int is_sp_move_ins(union mips_instruction *ip) return 0; } +static inline int is_sibling_j_ins(union mips_instruction *ip, + unsigned long func_begin, unsigned long func_end) +{ + if (ip->j_format.opcode == j_op) { + unsigned long addr; + + addr = J_TARGET(ip, ip->j_format.target); + if (addr < func_begin || addr > func_end) + return 1; + } + return 0; +} + static int get_frame_info(struct mips_frame_info *info) { union mips_instruction *ip = info->func; unsigned max_insns = info->func_size / sizeof(union mips_instruction); unsigned i; + unsigned long func_begin, func_end; info->pc_offset = -1; info->frame_size = 0; @@ -266,10 +283,15 @@ static int get_frame_info(struct mips_frame_info *info) max_insns = 128U; /* unknown function size */ max_insns = min(128U, max_insns); + func_begin = (unsigned long) info->func; + func_end = func_begin + max_insns * sizeof(union mips_instruction); + for (i = 0; i < max_insns; i++, ip++) { if (is_jal_jalr_jr_ins(ip)) break; + if (is_sibling_j_ins(ip, func_begin, func_end)) + break; if (!info->frame_size) { if (is_sp_move_ins(ip)) info->frame_size = - ip->i_format.simmediate; -- 1.7.10.2 (Apple Git-33)