From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2642 invoked by alias); 3 Jul 2013 09:15:27 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 2504 invoked by uid 89); 3 Jul 2013 09:15:26 -0000 X-Spam-SWARE-Status: No, score=-2.8 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,KHOP_THREADED,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE,SPF_PASS,TW_LR,TW_RW,TW_WX,TW_XR autolearn=ham version=3.3.1 Received: from mail-ve0-f179.google.com (HELO mail-ve0-f179.google.com) (209.85.128.179) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Wed, 03 Jul 2013 09:15:24 +0000 Received: by mail-ve0-f179.google.com with SMTP id d10so5670555vea.24 for ; Wed, 03 Jul 2013 02:15:22 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.52.248.206 with SMTP id yo14mr10391070vdc.61.1372841328785; Wed, 03 Jul 2013 01:48:48 -0700 (PDT) Received: by 10.52.22.73 with HTTP; Wed, 3 Jul 2013 01:48:48 -0700 (PDT) In-Reply-To: <20130703084207.GA598@host2.jankratochvil.net> References: <20130703084207.GA598@host2.jankratochvil.net> Date: Wed, 03 Jul 2013 09:15:00 -0000 Message-ID: Subject: Re: vdso From: vijay nag To: Jan Kratochvil Cc: gdb@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 X-SW-Source: 2013-07/txt/msg00013.txt.bz2 On Wed, Jul 3, 2013 at 2:12 PM, Jan Kratochvil wrote: > On Wed, 03 Jul 2013 10:34:43 +0200, vijay nag wrote: >> cat /proc/15896/smaps | grep vdso >> 778:b7fff000-b8000000 r-xp b7fff000 00:00 0 [vdso] >> >> Does vdso come with symbols ? > > For basic ELF symbols it does. Try: > dump memory /tmp/vdso.so 0xb7fff000 0xb8000000 > readelf -Ws /tmp/vdso.so > > and .dynsym section there should contain the symbols: > 4: ffffffffff700ba0 404 FUNC GLOBAL DEFAULT 15 __vdso_gettimeofday@@LINUX_2.6 > 5: ffffffffff700d60 61 FUNC GLOBAL DEFAULT 15 __vdso_getcpu@@LINUX_2.6 > etc. > > Then there are also DWARF symbols to see even filenames / line numbers but > those .debug_* sections at least Fedora ships only on disk in kernel-debuginfo > rpm. The symbols get loaded automatically by GDB: > lrwxrwxrwx 1 root root 61 Jul 2 00:43 /usr/lib/debug/.build-id/92/0bba09195bde2b45a7a4eaec1dc78c3157c0f5 -> ../../../../../lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so* > lrwxrwxrwx 1 root root 58 Jul 2 00:43 /usr/lib/debug/.build-id/92/0bba09195bde2b45a7a4eaec1dc78c3157c0f5.debug -> ../../lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so.debug > -rwxr-xr-x 1 root root 4856 Jun 28 16:56 /lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so* > -r--r--r-- 1 root root 104848 Jun 28 16:56 /usr/lib/debug/lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so.debug > $ rpm -qf /lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so /usr/lib/debug/lib/modules/3.9.8-200.fc18.x86_64/vdso/vdso.so.debug > kernel-3.9.8-200.fc18.x86_64 > kernel-debuginfo-3.9.8-200.fc18.x86_64 > > > You should check first /tmp/vdso.so to see whether your Linux kernel or GDB is > the problem. > > > Jan Following are output of readelf and something is surely amiss like you suggested readelf -Ws /tmp/vdso.so Symbol table '.dynsym' contains 9 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: ffffe400 0 SECTION LOCAL DEFAULT 6 2: ffffe478 0 SECTION LOCAL DEFAULT 8 3: ffffe480 0 SECTION LOCAL DEFAULT 9 4: ffffe618 0 SECTION LOCAL DEFAULT 11 5: ffffe400 20 FUNC GLOBAL DEFAULT 6 __kernel_vsyscall@@LINUX_2.5 6: 00000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.5 7: ffffe440 7 FUNC GLOBAL DEFAULT 6 __kernel_rt_sigreturn@@LINUX_2.5 8: ffffe420 8 FUNC GLOBAL DEFAULT 6 __kernel_sigreturn@@LINUX_2.5