From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13753 invoked by alias); 31 Mar 2011 13:58:15 -0000 Received: (qmail 13744 invoked by uid 22791); 31 Mar 2011 13:58:13 -0000 X-SWARE-Spam-Status: No, hits=-1.3 required=5.0 tests=AWL,BAYES_00,MSGID_FROM_MTA_HEADER,SPF_SOFTFAIL,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mtagate1.uk.ibm.com (HELO mtagate1.uk.ibm.com) (194.196.100.161) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 31 Mar 2011 13:58:03 +0000 Received: from d06nrmr1806.portsmouth.uk.ibm.com (d06nrmr1806.portsmouth.uk.ibm.com [9.149.39.193]) by mtagate1.uk.ibm.com (8.13.1/8.13.1) with ESMTP id p2VDvrsP020066 for ; Thu, 31 Mar 2011 13:57:53 GMT Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by d06nrmr1806.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p2VDwTW51503328 for ; Thu, 31 Mar 2011 14:58:29 +0100 Received: from d06av02.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p2VDvrIa027007 for ; Thu, 31 Mar 2011 07:57:53 -0600 Received: from tuxmaker.boeblingen.de.ibm.com (tuxmaker.boeblingen.de.ibm.com [9.152.85.9]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with SMTP id p2VDvp7s026986; Thu, 31 Mar 2011 07:57:51 -0600 Message-Id: <201103311357.p2VDvp7s026986@d06av02.portsmouth.uk.ibm.com> Received: by tuxmaker.boeblingen.de.ibm.com (sSMTP sendmail emulation); Thu, 31 Mar 2011 15:57:51 +0200 Subject: [rfc] Fix broken i386 signal unwinding (Re: graceful unwind termination when we'd need unavailable/uncollect memory or registers to unwind further) To: pedro@codesourcery.com (Pedro Alves) Date: Thu, 31 Mar 2011 14:43:00 -0000 From: "Ulrich Weigand" Cc: gdb-patches@sourceware.org In-Reply-To: <201102221834.42413.pedro@codesourcery.com> from "Pedro Alves" at Feb 22, 2011 06:34:42 PM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2011-03/txt/msg01214.txt.bz2 Pedro Alves wrote: > (i386_frame_prev_register): Handle unavailable SP. > - if (regnum == I386_ESP_REGNUM && cache->saved_sp) > - return frame_unwind_got_constant (this_frame, regnum, cache->saved_sp); > + if (regnum == I386_ESP_REGNUM) > + { > + /* If the SP has been saved, but we don't know where, then this > + means that SAVED_SP_REG register was found unavailable back > + when we built the cache. */ > + if (cache->saved_sp == 0 && cache->saved_sp_reg != -1) > + return frame_unwind_got_register (this_frame, regnum, > + cache->saved_sp_reg); > + else > + return frame_unwind_got_constant (this_frame, regnum, > + cache->saved_sp); > + } > > if (regnum < I386_NUM_SAVED_REGS && cache->saved_regs[regnum] != -1) > return frame_unwind_got_memory (this_frame, regnum, It seems this change broke unwinding out of signal trampoline frames on i386 for me. In this case, neither SAVED_SP nor SAVED_SP_REG is set; instead, SP is supposed to be unwound from memory (the trampoline stack frame) via SAVED_REGS. However, after your change, we now fall into the _got_constant case and SP is always unwound as 0. The following patch fixes this for me, and gets about 50 test cases back to PASS. Does this look right to you? Tested on i386-linux (Ubuntu Lucid). Bye, Ulrich ChangeLog: * i386-tdep.c (i386_frame_prev_register): Unwind SP from memory if neither saved value nor register available (e.g. signal frame). Index: gdb/i386-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/i386-tdep.c,v retrieving revision 1.330 diff -u -p -r1.330 i386-tdep.c --- gdb/i386-tdep.c 18 Mar 2011 18:52:30 -0000 1.330 +++ gdb/i386-tdep.c 31 Mar 2011 13:50:07 -0000 @@ -1798,12 +1798,13 @@ i386_frame_prev_register (struct frame_i if (regnum == I386_EIP_REGNUM && cache->pc_in_eax) return frame_unwind_got_register (this_frame, regnum, I386_EAX_REGNUM); - if (regnum == I386_ESP_REGNUM) + if (regnum == I386_ESP_REGNUM + && (cache->saved_sp != 0 || cache->saved_sp_reg != -1)) { /* If the SP has been saved, but we don't know where, then this means that SAVED_SP_REG register was found unavailable back when we built the cache. */ - if (cache->saved_sp == 0 && cache->saved_sp_reg != -1) + if (cache->saved_sp == 0) return frame_unwind_got_register (this_frame, regnum, cache->saved_sp_reg); else -- Dr. Ulrich Weigand GNU Toolchain for Linux on System z and Cell BE Ulrich.Weigand@de.ibm.com