From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC524C4363C for ; Sun, 4 Oct 2020 19:08:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BCFF2068E for ; Sun, 4 Oct 2020 19:08:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726536AbgJDTIJ (ORCPT ); Sun, 4 Oct 2020 15:08:09 -0400 Received: from lizzard.sbs.de ([194.138.37.39]:57812 "EHLO lizzard.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726085AbgJDTII (ORCPT ); Sun, 4 Oct 2020 15:08:08 -0400 X-Greylist: delayed 916 seconds by postgrey-1.27 at vger.kernel.org; Sun, 04 Oct 2020 15:08:07 EDT Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by lizzard.sbs.de (8.15.2/8.15.2) with ESMTPS id 094Iqc3F027724 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 4 Oct 2020 20:52:38 +0200 Received: from [167.87.242.108] ([167.87.242.108]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 094Iqb1u011919; Sun, 4 Oct 2020 20:52:38 +0200 Subject: Re: scripts/gdb: issues when loading modules after lx-symbols To: Stefano Garzarella , Kieran Bingham Cc: linux-kernel@vger.kernel.org, qemu-devel@nongnu.org References: From: Jan Kiszka Message-ID: <9e247182-2cc3-9fac-e12e-9743ef24ec43@siemens.com> Date: Sun, 4 Oct 2020 20:52:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.10.20 16:31, Stefano Garzarella wrote: > Hi, > I had some issues with gdb scripts and kernel modules in Linux 5.9-rc7. > > If the modules are already loaded, and I do 'lx-symbols', all work fine. > But, if I load a kernel module after 'lx-symbols', I had this issue: > > [ 5093.393940] invalid opcode: 0000 [#1] SMP PTI > [ 5093.395134] CPU: 0 PID: 576 Comm: modprobe Not tainted 5.9.0-rc7-ste-00010-gf0b671d9608d-dirty #2 > [ 5093.397566] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 > [ 5093.400761] RIP: 0010:do_init_module+0x1/0x270 > [ 5093.402553] Code: ff ff e9 cf fe ff ff 0f 0b 49 c7 c4 f2 ff ff ff e9 c1 fe ff ff e8 5f b2 65 00 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 cc <1f> 44 00 00 55 ba 10 00 00 00 be c0 0c 00 00 48 89 e5 41 56 41 55 > [ 5093.409505] RSP: 0018:ffffc90000563d18 EFLAGS: 00010246 > [ 5093.412056] RAX: 0000000000000000 RBX: ffffffffc010a0c0 RCX: 0000000000004ee3 > [ 5093.414472] RDX: 0000000000004ee2 RSI: ffffea0001efe188 RDI: ffffffffc010a0c0 > [ 5093.416349] RBP: ffffc90000563e50 R08: 0000000000000000 R09: 0000000000000002 > [ 5093.418044] R10: 0000000000000096 R11: 00000000000008a4 R12: ffff88807a0d1280 > [ 5093.424721] R13: ffffffffc010a110 R14: ffff88807a0d1300 R15: ffffc90000563e70 > [ 5093.427138] FS: 00007f018f632740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 > [ 5093.430037] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 5093.432279] CR2: 000055fbe282b239 CR3: 000000007922a006 CR4: 0000000000170ef0 > [ 5093.435096] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 5093.436765] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 5093.439689] Call Trace: > [ 5093.440954] ? load_module+0x24b6/0x27d0 > [ 5093.443212] ? __kernel_read+0xd6/0x150 > [ 5093.445140] __do_sys_finit_module+0xd3/0xf0 > [ 5093.446877] __x64_sys_finit_module+0x1a/0x20 > [ 5093.449098] do_syscall_64+0x38/0x50 > [ 5093.450877] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 5093.456153] RIP: 0033:0x7f018f75c43d > [ 5093.457728] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 2b 6a 0c 00 f7 d8 64 89 01 48 > [ 5093.466349] RSP: 002b:00007ffd7f080368 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 > [ 5093.470613] RAX: ffffffffffffffda RBX: 0000557e5c96f9c0 RCX: 00007f018f75c43d > [ 5093.474747] RDX: 0000000000000000 RSI: 0000557e5c964288 RDI: 0000000000000003 > [ 5093.478049] RBP: 0000000000040000 R08: 0000000000000000 R09: 0000000000000000 > [ 5093.481298] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000 > [ 5093.483725] R13: 0000557e5c964288 R14: 0000557e5c96f950 R15: 0000557e5c9775c0 > [ 5093.485778] Modules linked in: virtio_vdpa(+) vdpa sunrpc kvm_intel kvm irqbypass virtio_blk virtio_rng rng_core [last unloaded: virtio_vdpa] > [ 5093.488695] ---[ end trace 23712ecebc11f53c ]--- > > Guest kernel: Linux 5.9-rc7 > gdb: GNU gdb (GDB) Fedora 9.1-6.fc32 > I tried with QEMU 4.2.1 and the latest master branch: same issue. > > > I did some digging, and skipping the gdb 'add-symbol-file' command in symbol.py > avoid the issue, but of course I don't have the symbols loaded: > > diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py > index 1be9763cf8bb..eadfaa4d4907 100644 > --- a/scripts/gdb/linux/symbols.py > +++ b/scripts/gdb/linux/symbols.py > @@ -129,7 +129,7 @@ lx-symbols command.""" > filename=module_file, > addr=module_addr, > sections=self._section_arguments(module)) > - gdb.execute(cmdline, to_string=True) > + #gdb.execute(cmdline, to_string=True) > if module_name not in self.loaded_modules: > self.loaded_modules.append(module_name) > else: > > I tried several modules and this happens every time after '(gdb) lx-symbols'. > > Do you have any hints? > I assume you are debugging a kernel inside QEMU/KVM, right? Does it work without -enable-kvm? Debugging guests in KVM mode at least was unstable for a long time. I avoided setting soft-BPs - which is what the script does for the sake of tracking modules loading -, falling back to hw-BPs, as I had no time to debug that further. /Maybe/ that's the issue here. Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux