From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22024 invoked by alias); 27 Nov 2012 18:49:24 -0000 Received: (qmail 22007 invoked by uid 22791); 27 Nov 2012 18:49:23 -0000 X-SWARE-Spam-Status: No, hits=-4.3 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_THREADED,MSGID_FROM_MTA_HEADER,RCVD_IN_HOSTKARMA_W,RCVD_IN_HOSTKARMA_WL,RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from e06smtp14.uk.ibm.com (HELO e06smtp14.uk.ibm.com) (195.75.94.110) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 27 Nov 2012 18:49:19 +0000 Received: from /spool/local by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 27 Nov 2012 18:49:18 -0000 Received: from b06cxnps3074.portsmouth.uk.ibm.com (9.149.109.194) by e06smtp14.uk.ibm.com (192.168.101.144) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 27 Nov 2012 18:49:15 -0000 Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by b06cxnps3074.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id qARIn7BR4587788; Tue, 27 Nov 2012 18:49:07 GMT 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 qARInEcE031364; Tue, 27 Nov 2012 11:49:14 -0700 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 qARInCSZ031343; Tue, 27 Nov 2012 11:49:13 -0700 Message-Id: <201211271849.qARInCSZ031343@d06av02.portsmouth.uk.ibm.com> Received: by tuxmaker.boeblingen.de.ibm.com (sSMTP sendmail emulation); Tue, 27 Nov 2012 19:49:12 +0100 Subject: Re: [RFC] Wrong register numbers in .dwarf_frame on Linux/PowerPC To: mjw@redhat.com (Mark Wielaard) Date: Tue, 27 Nov 2012 18:49:00 -0000 From: "Ulrich Weigand" Cc: dje.gcc@gmail.com, geoffk@geoffk.org, jakub@redhat.com, gcc-patches@gcc.gnu.org, binutils@sourceware.org, gdb-patches@sourceware.org In-Reply-To: <1354008385.4706.36.camel@bordewijk.wildebeest.org> from "Mark Wielaard" at Nov 27, 2012 10:26:25 AM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit x-cbid: 12112718-1948-0000-0000-000003A2F5BA 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: 2012-11/txt/msg00771.txt.bz2 Mark Wielaard wrote: > Which other unwinders are out there, that might rely on the current > numbering? Well, runtime unwinders using .eh_frame should be fine, since this uses (and has always used) consistently the GCC numbering. I don't know if there are other unwinders using .dwarf_frame ... > The Systemtap runtime unwinder (*) currently is incomplete > (and in one case wrong since the numbering overlaps), so it doesn't > really matter much which solution you pick (we will just have to watch > out and fix things to be as consistent as possible when your change goes > through). If you do change the numbering it would be ideal if there was > a way to detect which one was in place (although it is probably hopeless > because depending on which GCC version is in use there can already be > different numberings). The change will most likely be to consistently use GCC numbering in .dwarf_frame as well, which changes only the encoding of the condition code register. Since you're not using that at all in systemtap, you shouldn't be affected. > BTW. The reason the systemtap runtime unwinder is > a little wrong here is because on all other architectures we assume > eh_frame and debug_frame DWARF register numberings are equal, is ppc > really the only architecture for which that isn't true, or were we just > lucky? As far as Linux goes, yes, ppc was the only architecture with a different encoding between .eh_frame and .dwarf_frame. The only other such platforms I'm aware of are Darwin on 32-bit i386, and some other operating systems on ppc (AIX, Darwin, BSD). Bye, Ulrich -- Dr. Ulrich Weigand GNU Toolchain for Linux on System z and Cell BE Ulrich.Weigand@de.ibm.com