From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25386 invoked by alias); 2 Jul 2010 14:14:44 -0000 Received: (qmail 25371 invoked by uid 22791); 2 Jul 2010 14:14:43 -0000 X-SWARE-Spam-Status: No, hits=-5.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 02 Jul 2010 14:14:39 +0000 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o62EEcSD027442 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 2 Jul 2010 10:14:38 -0400 Received: from [10.36.11.99] (vpn2-11-99.ams2.redhat.com [10.36.11.99]) by int-mx03.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o62EEaer013870; Fri, 2 Jul 2010 10:14:37 -0400 Subject: Re: A 48 byte kernel module/cfi load mystery From: Mark Wielaard To: roland@redhat.com Cc: systemtap@sourceware.org In-Reply-To: <1278069785.4626.29.camel@springer.wildebeest.org> References: <1278069785.4626.29.camel@springer.wildebeest.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 02 Jul 2010 14:14:00 -0000 Message-ID: <1278080076.4626.35.camel@springer.wildebeest.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit 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: 2010-q3/txt/msg00008.txt.bz2 On Fri, 2010-07-02 at 13:23 +0200, Mark Wielaard wrote: > I cannot figure out why the FDE initial_location is shifted by 48 bytes. > If in the stap unwinder I just pretend the kernel module has been loaded > a little earlier: > > - vm_addr = s->static_addr; > + vm_addr = s->static_addr - 0x30; > > all the CFIs line up and I can unwind perfectly through the kernel > modules. But this mysterious magic 48 bytes bothers me. It is the same > on i686 btw. Any idea where they might be coming from? Actually it isn't always the same. It was for that kernel on both x86_64 and i686. But with a recent fedora x86_64 kernel (2.6.33.5-124.fc13.x86_64) the offset is always 0x24. Cheers, Mark