From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20197 invoked by alias); 25 Feb 2009 01:55:40 -0000 Received: (qmail 20098 invoked by uid 22791); 25 Feb 2009 01:55:39 -0000 X-SWARE-Spam-Status: No, hits=-1.7 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 25 Feb 2009 01:55:31 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n1P1tRKT024777; Tue, 24 Feb 2009 20:55:27 -0500 Received: from gateway.sf.frob.com (vpn-13-44.rdu.redhat.com [10.11.13.44]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n1P1tRu9028055; Tue, 24 Feb 2009 20:55:28 -0500 Received: from magilla.sf.frob.com (magilla.sf.frob.com [198.49.250.228]) by gateway.sf.frob.com (Postfix) with ESMTP id 3358F357B; Tue, 24 Feb 2009 17:55:26 -0800 (PST) Received: by magilla.sf.frob.com (Postfix, from userid 5281) id F244FFC380; Tue, 24 Feb 2009 17:55:25 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: "Frank Ch. Eigler" Cc: systemtap@sources.redhat.com Subject: Re: rfc patch for buildid < shlib base address In-Reply-To: Frank Ch. Eigler's message of Tuesday, 24 February 2009 20:46:22 -0500 <20090225014622.GA17348@elastic.org> References: <20090225014622.GA17348@elastic.org> Message-Id: <20090225015525.F244FFC380@magilla.sf.frob.com> Date: Wed, 25 Feb 2009 02:38:00 -0000 X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q1/txt/msg00516.txt.bz2 > On my i686 F10 box, elfutils 0.140 probing /lib/libc-2.9.so, the > buildid data logic results in an address that is smaller than the dwfl > relocation base address for the module. readelf indicates the > build-id .note section well before .text. This causes a negative > offset, which in turn causes a pass-4 compile error. It is normal that the build ID note appear earlier than the .text section. What is not normal is that you should care about the .text section's location at all. For any non-ET_REL module, the sole relocation base should correspond to the beginning of its earliest PT_LOAD. (In fact, libdwfl doesn't really care if no section info was retained at all in the stripped file; canonical tools don't strip that way, but they could.) This is by definition an address lower than where the note (or anything else) appears. Thanks, Roland