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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9C890C433E0 for ; Thu, 21 May 2020 14:26:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 268B92072C for ; Thu, 21 May 2020 14:26:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 268B92072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38700 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jbm9m-0006EK-5l for qemu-devel@archiver.kernel.org; Thu, 21 May 2020 10:26:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33672) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jbm96-0005hY-ED for qemu-devel@nongnu.org; Thu, 21 May 2020 10:26:04 -0400 Received: from indium.canonical.com ([91.189.90.7]:59010) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jbm95-00070W-5h for qemu-devel@nongnu.org; Thu, 21 May 2020 10:26:04 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1jbm91-0006Vn-4p for ; Thu, 21 May 2020 14:25:59 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 7DF7F2E819F for ; Thu, 21 May 2020 14:25:54 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 21 May 2020 14:19:40 -0000 From: Peter Maydell <1877136@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Fix Committed; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: arm X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: matmal01 pmaydell X-Launchpad-Bug-Reporter: Matthew (matmal01) X-Launchpad-Bug-Modifier: Peter Maydell (pmaydell) References: <158877804267.5105.15160019007007013161.malonedeb@chaenomeles.canonical.com> Message-Id: <159007078103.7211.15588578918744226444.malone@gac.canonical.com> Subject: [Bug 1877136] Re: Qemu GDB Arm core registers XML description not valid for M-profile X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="1f7bc749b40714a4cc10f5e4d787118a78037035"; Instance="production-secrets-lazr.conf" X-Launchpad-Hash: 8d9762e4786034fec1f03bf47074d23adee4941c Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/21 08:50:51 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1877136 <1877136@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Fix now in master, will be in QEMU 5.1. ** Changed in: qemu Status: In Progress =3D> Fix Committed -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1877136 Title: Qemu GDB Arm core registers XML description not valid for M-profile Status in QEMU: Fix Committed Bug description: When trying to debug an armv7-m binary running on Qemu, GDB makes some mistakes due to mistakenly believing the target is not M-profile. One observable is that backtraces over signal handlers are not handled correctly -- since the special M-profile EXC_RETURN value is not recognised. That happens because GDB doesn't think the target is M-profile. This happens because GDB sees a reported feature set from the Qemu remote connection that includes the feature `org.gnu.gdb.arm.core`. As described in the GDB online docs, for "M-profile targets (e.g. Cortex-= M3), the =E2=80=98org.gnu.gdb.arm.core=E2=80=99 feature is replaced by =E2= =80=98org.gnu.gdb.arm.m-profile=E2=80=99" https://sourceware.org/gdb/current/onlinedocs/gdb/ARM-Features.html From a scan of the Qemu source code on commit ea1329bb3a8d5cd25b70e3dbf73e7ded4d5ad756 it seems that when emulating an arm core it uses `arm-core.xml` unconditionally for `CPUClass->gdb_core_xml_file`, and that means the only feature provided is `org.gnu.gdb.arm.core`. Note that even though there is a command to set the architecture in GDB, = setting the target architecture to an M-profile core is still not a valid w= orkaround. This is because the target description overrides everything in setting th= e `is_m` attribute within GDB. Reproduction of the observable: Using the examples here https://git.linaro.org/people/peter.maydell/m-pro= file-tests.git/tree/ . Build the examples, and run = ``` qemu-system-arm -s -S -no-reboot -M lm3s6965evb -m 16 -serial stdio -disp= lay none -net nic -net user,restrict=3Don -d guest_errors,unimp -kernel tes= t3-kern.bin ``` Then in a GDB session ``` vshcmd: > arm-none-eabi-gdb -q = = = (gdb) vshcmd: > file test3-kern.elf Reading symbols from test3-kern.elf... (gdb) vshcmd: > target remote localhost:1234 Remote debugging using localhost:1234 _start () at init-m.S:53 53 mov r0, #0 (gdb) vshcmd: > show architecture The target architecture is set automatically (currently armv7) (gdb) vshcmd: > break svc Breakpoint 1 at 0x6fc: svc. (2 locations) (gdb) vshcmd: > cont Continuing. Breakpoint 1, svc () at test3.c:16 16 int test =3D SEQ(); (gdb) vshcmd: > bt #0 svc () at test3.c:16 #1 0xfffffff8 in ?? () Backtrace stopped: previous frame identical to this frame (corrupt stack?) (gdb) vshcmd: > print/x $lr $1 =3D 0xfffffff9 (gdb) ``` To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1877136/+subscriptions