From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 10 May 2013 13:07:47 +0200 (CEST) Received: from mail-pa0-f47.google.com ([209.85.220.47]:36185 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6816354Ab3EJLHoZoM0T (ORCPT ); Fri, 10 May 2013 13:07:44 +0200 Received: by mail-pa0-f47.google.com with SMTP id kl13so2854673pab.34 for ; Fri, 10 May 2013 04:07:37 -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=pYFvTaBcgd3j4tAUbHVy56TG0nXHb0le3K3r/Q1EI83pCG6WYqmrHnjqc2y6Sxq/H5 IFvNLWSkLaACfz+FB02Op7a9tLPF7NhtB0SL9cx9/xl4u0oZmJnxUbcnKKc7tcnD4vi6 ayaIw3B5GCcwsnrDhkmZHhk7ypXr1loLiA/J4HMIv0TRijtOBSv1tGC8mRhlZbkXp4pX htpXmwisvPQz5My67XseSlPVVzWdfMg0cF3wnqrmO4Gzb8R2NVFhO1zCBoFZ64cW9MC9 w3VPg7/WG3oIil0T+jtb5Ff3De2VgypMJQn1OmPiv+osbrLAK4+/EnNTbzWc77PhLscw c06A== X-Received: by 10.68.134.6 with SMTP id pg6mr16761273pbb.39.1368184057683; Fri, 10 May 2013 04:07:37 -0700 (PDT) Received: from hades (1-169-131-150.dynamic.hinet.net. [1.169.131.150]) by mx.google.com with ESMTPSA id fx2sm2533303pac.4.2013.05.10.04.07.34 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 10 May 2013 04:07:35 -0700 (PDT) Date: Fri, 10 May 2013 19:07:29 +0800 From: Tony Wu To: ralf@linux-mips.org, linux-mips@linux-mips.org Subject: [PATCH v2 1/2] MIPS: detect sibling call in get_frame_info Message-ID: <20130510110729.GA7499@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: 36377 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)