From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from v22018116198577468.luckysrv.de (tikei.de [188.68.34.133]) by sourceware.org (Postfix) with ESMTP id 3EE323844023 for ; Tue, 18 May 2021 13:34:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 3EE323844023 Received: from smtpclient.apple (unknown [80.149.95.59]) by v22018116198577468.luckysrv.de (Postfix) with ESMTPSA id 1718A4007D for ; Tue, 18 May 2021 15:34:29 +0200 (CEST) From: Tino Mettler Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.80.0.2.43\)) Subject: Re: Missing .gnu_debugdata section on ARM platform when libdw is used by systemd-coredump Date: Tue, 18 May 2021 15:33:27 +0200 References: <892EDCB7-C2A8-4497-8FF1-986A63EA7F4A@tikei.de> <2425384793cfe2a31e8d4d0c76b36d40f6e5304b.camel@klomp.org> To: elfutils-devel@sourceware.org In-Reply-To: <2425384793cfe2a31e8d4d0c76b36d40f6e5304b.camel@klomp.org> Message-Id: X-Mailer: Apple Mail (2.3654.80.0.2.43) X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: elfutils-devel@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Elfutils-devel mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 May 2021 13:34:33 -0000 Hi Mark, Am 06.05.2021 um 02:49 schrieb Mark Wielaard : > > Hi Tino, > > On Tue, 2021-05-04 at 14:15 +0200, Tino Mettler via Elfutils-devel > wrote: >> I have a system running on 2 different architectures: AMD64 and ARM. >> When a coredump happens, I want systemd-coredump to generate a stack >> trace of the crashing application. Systemd depends on elfutils for >> this feature. I use binaries with minidebuginfo (the LZMA compressed >> symbol table in the .gnu_debugdata section) on both architectures. >> >> I get a stack trace on AMD64, but not on ARM. While debugging this, I >> saw that find_aux_sym() from dwfl_module_getdwarf.c does not find a >> .gnu_debugdata section when iterating through the ELF using >> elf_nextscn(). >> >> However, it finds a .gnu_debuglink section. I inspected the >> executable and verified that it contains a .gnu_debugdata section and >> it looks fine. Interestingly, there is no .gnu_debuglink section in >> the executable despite elf_nextscn() seems to find one. >> >> It looks like libdw does not process the actual executable, but a >> modified variant, and the .gnu_debugdata section gets lost at some >> point on my ARM device. Can you give me a hint where I need to look >> at? Both devices run a different kernel with a different >> configuration. Could that be related? > > If possible you might want to post the core file and/or executables > somewhere so others can inspect them. I am not completely sure how the > .gnu_debugdata (aux symbols) is related. Are you getting a backtrace, > but not function symbols for the addresses? I'll try to provide a minimal example for this. I get only frame #0 of the stack and no complete stack trace. > > For ARM it might depend on whether the executable contains an .eh_frame > sections. If it has (or the .debug file has an .debug_frame section) > then libdw should be able to produce a backtrace. > > But there are also ARM binaries which only come with IDX data, which > libdw doesn't handle. There is a .eh_frame in the binary. Regards, Tino