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=-18.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 9696AC433B4 for ; Wed, 14 Apr 2021 10:41:16 +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 353EE611CC for ; Wed, 14 Apr 2021 10:41:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 353EE611CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51624 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lWcxP-0001Tj-16 for qemu-devel@archiver.kernel.org; Wed, 14 Apr 2021 06:41:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57172) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lWcw6-0000Zx-5X for qemu-devel@nongnu.org; Wed, 14 Apr 2021 06:39:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:26865) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lWcw3-0002iX-6y for qemu-devel@nongnu.org; Wed, 14 Apr 2021 06:39:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618396790; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VRbKEwBBzZ54ewNUKDgX5oMV/h7K2yEn6WAmSxVoFwg=; b=O5tayKft2BM5P+qKmAZbbgqppdBMnpR8zqpHUDrR6C2u978ECY/aOiy0SVqKniKSAUj/7m iZX0rub5lbZsUBBxrmYXLc6UX4cQrndh0n6CZbx6pUAHSM9ykGLzEloq1g1PUhJ7OxRoB0 ig1inlmZG0jgvX0txcQg4MI3IhMP3gk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-579-hvLUPgUvPRuyoqw-PYhp7Q-1; Wed, 14 Apr 2021 06:39:48 -0400 X-MC-Unique: hvLUPgUvPRuyoqw-PYhp7Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D2DD9107ACC7; Wed, 14 Apr 2021 10:39:46 +0000 (UTC) Received: from gondolin (ovpn-113-114.ams2.redhat.com [10.36.113.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1BCE65D9CC; Wed, 14 Apr 2021 10:39:38 +0000 (UTC) Date: Wed, 14 Apr 2021 12:39:36 +0200 From: Cornelia Huck To: Ilya Leoshkevich Subject: Re: [PATCH v2] target/s390x: Fix translation exception on illegal instruction Message-ID: <20210414123936.05f9759a.cohuck@redhat.com> In-Reply-To: <710e154736b7e118ae12587a468a8c198cab028c.camel@linux.ibm.com> References: <20210413165257.21426-1-iii@linux.ibm.com> <20210414103813.2595508b.cohuck@redhat.com> <9ffa39db0e16efa173119d3b9746bb312e214d87.camel@linux.ibm.com> <710e154736b7e118ae12587a468a8c198cab028c.camel@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , David Hildenbrand , Richard Henderson , qemu-devel@nongnu.org, Christian Borntraeger , qemu-s390x@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 14 Apr 2021 12:27:03 +0200 Ilya Leoshkevich wrote: > On Wed, 2021-04-14 at 11:19 +0200, Ilya Leoshkevich wrote: > > On Wed, 2021-04-14 at 10:38 +0200, Cornelia Huck wrote: =20 > > > On Tue, 13 Apr 2021 18:52:57 +0200 > > > Ilya Leoshkevich wrote: > > > =20 > > > > Hitting an uretprobe in a s390x TCG guest causes a SIGSEGV. What > > > > happens is: > > > >=20 > > > > * uretprobe maps a userspace page containing an invalid > > > > instruction. > > > > * uretprobe replaces the target function's return address with the > > > > =C2=A0 address of that page. > > > > * When tb_gen_code() is called on that page, tb->size ends up being > > > > 0 > > > > =C2=A0 (because the page starts with the invalid instruction), whic= h > > > > causes > > > > =C2=A0 virt_page2 to point to the previous page. > > > > * The previous page is not mapped, so this causes a spurious > > > > =C2=A0 translation exception. > > > >=20 > > > > The bug is that tb->size must never be 0: even if there is an > > > > illegal > > > > instruction, the instruction bytes that have been looked at must > > > > count > > > > towards tb->size. So adjust s390x's translate_one() to act this way > > > > for both illegal instructions and instructions that are known to > > > > generate exceptions. > > > >=20 > > > > Also add an assertion to tb_gen_code() in order to detect such > > > > situations in future. > > > >=20 > > > > Signed-off-by: Ilya Leoshkevich > > > > --- > > > >=20 > > > > v1:=20 > > > > https://lists.nongnu.org/archive/html/qemu-devel/2021-04/msg02037.h= tml > > > > v1 -> v2: Fix target/s390x instead of trying to tolerate tb->size > > > > =3D=3D 0 > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 in tb_gen_co= de(). > > > >=20 > > > > =C2=A0accel/tcg/translate-all.c |=C2=A0 1 + > > > > =C2=A0target/s390x/translate.c=C2=A0 | 16 +++++++++++----- > > > > =C2=A02 files changed, 12 insertions(+), 5 deletions(-) =20 > > >=20 > > > I assume this bug is not usually hit during normal usage, right? It's > > > probably not release critical, so I'll line it up for 6.1 instead. = =20 > >=20 > > Yes, I saw it only with uprobes, and then it leads only to a process > > crash, not to a kernel crash. Thanks! =20 >=20 > Seems like the new assertion triggers on ARM: >=20 > https://gitlab.com/cohuck/qemu/-/jobs/1178409450 Yep, I just wanted to make sure it was this patch before complaining :) >=20 > What are the rules in s390x-next-staging, can we amend the patch, or > only commit a follow-up?=20 -staging is before I merge properly, so no problem folding something in. > In either case, I think we'll need something > like this (untested): >=20 > --- a/target/arm/translate.c > +++ b/target/arm/translate.c > @@ -9060,6 +9060,7 @@ static void > arm_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu) > unsigned int insn; > =20 > if (arm_pre_translate_insn(dc)) { > + dc->base.pc_next +=3D 4; > return; > } >=20 >=20 > I'm currently trying to debug this in more detail and test the fix. >=20