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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 E9D2CC433ED for ; Wed, 7 Apr 2021 09:01:47 +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 0F9A261205 for ; Wed, 7 Apr 2021 09:01:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F9A261205 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]:45208 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lU44H-0000XM-RQ for qemu-devel@archiver.kernel.org; Wed, 07 Apr 2021 05:01:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34702) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lU43V-0008K6-2m for qemu-devel@nongnu.org; Wed, 07 Apr 2021 05:00:57 -0400 Received: from indium.canonical.com ([91.189.90.7]:47418) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lU43R-0006JO-U9 for qemu-devel@nongnu.org; Wed, 07 Apr 2021 05:00:56 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1lU43O-0004tq-EP for ; Wed, 07 Apr 2021 09:00:50 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 628F92E8010 for ; Wed, 7 Apr 2021 09:00:50 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 07 Apr 2021 08:53:58 -0000 From: Peter Maydell <1922887@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=New; 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: muhui X-Launchpad-Bug-Reporter: JIANG Muhui (muhui) X-Launchpad-Bug-Modifier: Peter Maydell (pmaydell) References: <161778201158.26656.2798489764705445614.malonedeb@wampee.canonical.com> Message-Id: <161778563931.29743.5263018292652812742.launchpad@gac.canonical.com> Subject: [Bug 1922887] Re: STR in Thumb 32 decode problem 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="57f1f603f707b9cfa764cae8dd0f3999026b4763"; Instance="production" X-Launchpad-Hash: 8167066ba15158ace433e912021edc3c8a1aaa40 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com 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, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no 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 1922887 <1922887@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" ** Tags added: arm -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1922887 Title: STR in Thumb 32 decode problem Status in QEMU: New Bug description: Hi It seems that QEMU does not have a proper check on the STR instruction in Thumb32 mode. Specifically, the machine code is 0xf84f0ddd, which is 0b1111 1000 0100 1= 111 0000 1101 1101 1101. = This is an STR (immediate, Thumb) instruction with a T4 encoding scheme. The symbols is Rn =3D 1111 Rt =3D 0000 P =3D 1 U =3D 0 W =3D 1 The decode ASL is below: if P =3D=3D =E2=80=981=E2=80=99 && U =3D=3D =E2=80=981=E2=80=99 && W =3D= =3D =E2=80=980=E2=80=99 then SEE STRT; if Rn =3D=3D =E2=80=981101=E2=80=99 && P =3D=3D =E2=80=981=E2=80=99 && U = =3D=3D =E2=80=980=E2=80=99 && W =3D=3D =E2=80=981=E2=80=99 && imm8 =3D=3D = =E2=80=9800000100=E2=80=99 then SEE PUSH; if Rn =3D=3D =E2=80=981111=E2=80=99 || (P =3D=3D =E2=80=980=E2=80=99 && W= =3D=3D =E2=80=980=E2=80=99) then UNDEFINED; t =3D UInt(Rt); n =3D UInt(Rn); imm32 =3D ZeroExtend(imm8, 32); index =3D (P =3D=3D =E2=80=981=E2=80=99); add =3D (U =3D=3D =E2=80=981=E2= =80=99); wback =3D (W =3D=3D =E2=80=981=E2=80=99); if t =3D=3D 15 || (wback && n =3D=3D t) then UNPREDICTABLE; When Rn =3D=3D 1111, it should be an undefined instruction, which should raise SEGILL signal. However, it seems that QEMU does not check this constraint, which should be a bug. Many thanks Regards Muhui To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1922887/+subscriptions