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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A7EEC83F01 for ; Wed, 30 Aug 2023 12:38:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4DDCE440149; Wed, 30 Aug 2023 08:38:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 48D78440009; Wed, 30 Aug 2023 08:38:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3080D440149; Wed, 30 Aug 2023 08:38:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 22A91440009 for ; Wed, 30 Aug 2023 08:38:15 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id E7E79140129 for ; Wed, 30 Aug 2023 12:38:14 +0000 (UTC) X-FDA: 81180723708.30.306CBF8 Received: from EUR03-AM7-obe.outbound.protection.outlook.com (mail-am7eur03on2074.outbound.protection.outlook.com [40.107.105.74]) by imf04.hostedemail.com (Postfix) with ESMTP id 54DE840029 for ; Wed, 30 Aug 2023 12:38:09 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b="0HECq+n/"; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b="0HECq+n/"; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf04.hostedemail.com: domain of Szabolcs.Nagy@arm.com designates 40.107.105.74 as permitted sender) smtp.mailfrom=Szabolcs.Nagy@arm.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693399091; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=wV8mPRMaR1P1rFQgy90FKbO/pA1JI7UIbXfKBiXscyc=; b=fxnelEl+p8SqExPf/d+tbvw0Z1w+UtONhPtHy7dMcs4YMnZgIU3sIKs+6dhHjvHIISu78u vU5lxj2BwcQb7RD5oltlIn30rKFtjmOSYqnDXabntLz6M30QEtcQY5IJgVFpnDENa/JkRv Z3eLyYShMgU5omEaUnZGSbwXpRHSicU= ARC-Authentication-Results: i=2; imf04.hostedemail.com; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b="0HECq+n/"; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b="0HECq+n/"; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf04.hostedemail.com: domain of Szabolcs.Nagy@arm.com designates 40.107.105.74 as permitted sender) smtp.mailfrom=Szabolcs.Nagy@arm.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1693399091; a=rsa-sha256; cv=fail; b=ND0cQeQ9GKgSiahrPV4P6GNVcLVbQl/ldfcdArXdyLyYuIE/cQ/QjZJqAq2ZVmXEqAofrM vHwGaHuaT/WiygF/JnSTXlWMW/CL18NB1pknGdhEun57c6xfi64UgfqNp7XOsrV/AYiJk+ qanwRNyJhWD/ztVvq+DSX4RSt/VJazk= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector2-armh-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=wV8mPRMaR1P1rFQgy90FKbO/pA1JI7UIbXfKBiXscyc=; b=0HECq+n//99ifwPs3hI25BCyHpAMZZ8HmFsRml8mk4x3kt/6OnDOi0++4f4yiddYjjNsBjMCJOjEsd4G99DKZetc2Bd2gbKzDK5+zZn2ix5flWm/lmTGQdA+R4aDSPQ/iIILQXAQ84ofVyyJel8VLLMUe53rn3fOi/T1LN4B7c8= Received: from DU6P191CA0055.EURP191.PROD.OUTLOOK.COM (2603:10a6:10:53e::26) by DB9PR08MB8315.eurprd08.prod.outlook.com (2603:10a6:10:3dd::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6745.20; Wed, 30 Aug 2023 12:38:04 +0000 Received: from DBAEUR03FT051.eop-EUR03.prod.protection.outlook.com (2603:10a6:10:53e:cafe::f8) by DU6P191CA0055.outlook.office365.com (2603:10a6:10:53e::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6745.20 via Frontend Transport; Wed, 30 Aug 2023 12:38:04 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 63.35.35.123) smtp.mailfrom=arm.com; dkim=pass (signature was verified) header.d=armh.onmicrosoft.com;dmarc=pass action=none header.from=arm.com; Received-SPF: Pass (protection.outlook.com: domain of arm.com designates 63.35.35.123 as permitted sender) receiver=protection.outlook.com; client-ip=63.35.35.123; helo=64aa7808-outbound-1.mta.getcheckrecipient.com; pr=C Received: from 64aa7808-outbound-1.mta.getcheckrecipient.com (63.35.35.123) by DBAEUR03FT051.mail.protection.outlook.com (100.127.142.148) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6745.20 via Frontend Transport; Wed, 30 Aug 2023 12:38:03 +0000 Received: ("Tessian outbound 169aaa6bf2b7:v175"); Wed, 30 Aug 2023 12:38:03 +0000 X-CheckRecipientChecked: true X-CR-MTA-CID: f3df13224b1ec5d9 X-CR-MTA-TID: 64aa7808 Received: from 0e08af961bde.2 by 64aa7808-outbound-1.mta.getcheckrecipient.com id A930DF65-6BEA-493C-90C7-95D9A52A42EA.1; Wed, 30 Aug 2023 12:37:53 +0000 Received: from EUR03-AM7-obe.outbound.protection.outlook.com by 64aa7808-outbound-1.mta.getcheckrecipient.com with ESMTPS id 0e08af961bde.2 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384); Wed, 30 Aug 2023 12:37:53 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=QhSWutMyJ1kSENpbrpQZWrTUeJcqMGO4/nJxBzKoKGP0b6PqtRgz5sDosrqxeop9uSlq9j3tuOcMK6o0LqkrUvJHHYUHIRWSGGzDGdzy1Aac7no8MMAszMVgNaBmMnI9qdyQ+gHK2PmHUd+SaZCPaCIhbsIC7o7kVMPYD7RM9zjYE1zIIZmnkV5Xz8fFJhpQMlncfrpEBrYaqvDdbu9MRD9YeaQDSPQyFrrzExx7sH2fffliO5redpoLN9mHYDvHvgJerd88+4mLhtn66jOo2Bs/Bg/D4uJgfJGpREZHdJte5ZNgZ5biUDkxYpB9Q+sUwl1IN2iVZkaRCM+zKWKBzQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=wV8mPRMaR1P1rFQgy90FKbO/pA1JI7UIbXfKBiXscyc=; b=lQK7A0ALSYRQUMmHvrZQnrtBr+hFioYgWXxmg1snXS7uh4KqhyKprV8TFxLa4ZyS3qD79XkY/6K4oJGKEk6/OuOILUIF/eHJCtY0aD/sgmsDla5CVMCuKgLHq2+w3hEAyUE/XVCOy3sQSq7Iwz+0/H7x2T1aA92LC1SwwMQwcn9e9smMCCwJsIJaGiSPxyL/CqHyA02aDWgc52H4YrJnPsJ+8VS+tzEIHDj6c8SDe41xoZ1IqkIym6kTiO1QU0fcjXLlhTM/KQ12FUD9AgHlO8v/KnH3Swjom6ww2P9aJ0HaswUG/gakTJzvqZ/0YMiqg9vT3/ysEYDpUs72bVU5pA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector2-armh-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=wV8mPRMaR1P1rFQgy90FKbO/pA1JI7UIbXfKBiXscyc=; b=0HECq+n//99ifwPs3hI25BCyHpAMZZ8HmFsRml8mk4x3kt/6OnDOi0++4f4yiddYjjNsBjMCJOjEsd4G99DKZetc2Bd2gbKzDK5+zZn2ix5flWm/lmTGQdA+R4aDSPQ/iIILQXAQ84ofVyyJel8VLLMUe53rn3fOi/T1LN4B7c8= Authentication-Results-Original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; Received: from DB9PR08MB7179.eurprd08.prod.outlook.com (2603:10a6:10:2cc::19) by DB9PR08MB6393.eurprd08.prod.outlook.com (2603:10a6:10:25a::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6745.20; Wed, 30 Aug 2023 12:37:50 +0000 Received: from DB9PR08MB7179.eurprd08.prod.outlook.com ([fe80::adb0:61cb:8733:6db2]) by DB9PR08MB7179.eurprd08.prod.outlook.com ([fe80::adb0:61cb:8733:6db2%7]) with mapi id 15.20.6745.020; Wed, 30 Aug 2023 12:37:50 +0000 Date: Wed, 30 Aug 2023 13:37:33 +0100 From: Szabolcs Nagy To: Catalin Marinas , Mark Brown Cc: Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v4 03/36] arm64/gcs: Document the ABI for Guarded Control Stacks Message-ID: References: <43ec219d-bf20-47b8-a5f8-32bc3b64d487@sirena.org.uk> <227e6552-353c-40a9-86c1-280587a40e3c@sirena.org.uk> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: LO4P123CA0550.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:319::20) To DB9PR08MB7179.eurprd08.prod.outlook.com (2603:10a6:10:2cc::19) MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: DB9PR08MB7179:EE_|DB9PR08MB6393:EE_|DBAEUR03FT051:EE_|DB9PR08MB8315:EE_ X-MS-Office365-Filtering-Correlation-Id: 88053c5c-6e2d-400f-ef6c-08dba955f42f x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0; X-Microsoft-Antispam-Message-Info-Original: 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 X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DB9PR08MB7179.eurprd08.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(346002)(39860400002)(136003)(376002)(366004)(396003)(451199024)(1800799009)(186009)(6486002)(6666004)(6512007)(6506007)(83380400001)(478600001)(2906002)(26005)(110136005)(7416002)(41300700001)(66476007)(66946007)(66556008)(54906003)(316002)(8676002)(8936002)(5660300002)(4326008)(36756003)(2616005)(38100700002)(86362001)(66899024);DIR:OUT;SFP:1101; X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB9PR08MB6393 Original-Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; X-EOPAttributedMessage: 0 X-MS-Exchange-Transport-CrossTenantHeadersStripped: DBAEUR03FT051.eop-EUR03.prod.protection.outlook.com X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id-Prvs: 8116f766-498c-49e6-ce34-08dba955eb68 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:63.35.35.123;CTRY:IE;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:64aa7808-outbound-1.mta.getcheckrecipient.com;PTR:ec2-63-35-35-123.eu-west-1.compute.amazonaws.com;CAT:NONE;SFS:(13230031)(4636009)(346002)(39860400002)(376002)(396003)(136003)(186009)(82310400011)(1800799009)(451199024)(40470700004)(36840700001)(46966006)(66899024)(36756003)(2906002)(54906003)(70586007)(70206006)(110136005)(316002)(40480700001)(41300700001)(40460700003)(6512007)(36860700001)(6666004)(6506007)(5660300002)(6486002)(107886003)(26005)(336012)(47076005)(83380400001)(2616005)(86362001)(356005)(82740400003)(8936002)(4326008)(81166007)(478600001)(8676002);DIR:OUT;SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Aug 2023 12:38:03.6059 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 88053c5c-6e2d-400f-ef6c-08dba955f42f X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[63.35.35.123];Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com] X-MS-Exchange-CrossTenant-AuthSource: DBAEUR03FT051.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB9PR08MB8315 X-Rspamd-Queue-Id: 54DE840029 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: kdzywjeoru4hmyjsbzke55sh9k8tbxci X-HE-Tag: 1693399089-866651 X-HE-Meta: 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 xDt3aUjk 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The 08/24/2023 16:43, Catalin Marinas wrote: > Is there a use-case for the unlocked configuration to allow disabling > the GCS implicitly via a clone syscall? how would you handle clone or clone3 without gcs specified? (in the cases when clone creates a new thread with new stack) (1) fail. (2) allocate gcs. (3) disable gcs. the problem with (1) is that it requires changes to user code (this only affects code outside the libc doing something special since raw clone thread cannot call into the libc, all executing code have to be tightly controlled. i don't know how common this is, but i at least expect it in test code for system level tools like debuggers, strace, valgrind, qemu-system, seccomp filters etc. if it appears in actual use then that's a deployment issue for distros: note that changing clone to clone3 is non-trivial: it requires fallback logic and may have to deal with seccomp filters). problem with (2) is that the size policy and lifetime management is in the kernel then. (since only special cases are affected i guess that is ok, but i assumed we want to avoid this by moving to clone3 and user managed gcs). the problem with (3) is escaping the security measure, however it only applies to very special threads that can always decide to opt-in to gcs, so i don't see this as such a bad option and at least bw compat with existing code. (in my threat model the attacker cannot hijack clone syscalls as that seems stronger than hijacking return addresses.) so i guess the answer depends on how much headache failing raw clone may cause and i don't know that.