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 03982E732F5 for ; Thu, 28 Sep 2023 17:00:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6F6366B020D; Thu, 28 Sep 2023 13:00:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A5776B020E; Thu, 28 Sep 2023 13:00:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4F8036B020F; Thu, 28 Sep 2023 13:00:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 406A96B020D for ; Thu, 28 Sep 2023 13:00:32 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 0988340EC8 for ; Thu, 28 Sep 2023 17:00:32 +0000 (UTC) X-FDA: 81286619904.21.FBE730B Received: from EUR04-VI1-obe.outbound.protection.outlook.com (mail-vi1eur04on2052.outbound.protection.outlook.com [40.107.8.52]) by imf15.hostedemail.com (Postfix) with ESMTP id 5BD8BA0036 for ; Thu, 28 Sep 2023 17:00:27 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b=6PsOF7lu; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b=6PsOF7lu; spf=pass (imf15.hostedemail.com: domain of Szabolcs.Nagy@arm.com designates 40.107.8.52 as permitted sender) smtp.mailfrom=Szabolcs.Nagy@arm.com; dmarc=pass (policy=none) header.from=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=1695920428; 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=f+fE+7tV/oLB1Wx7LngAySEDb25Fz+qf9JsKa6Wgwp8=; b=IXjXaJfwcD70prLEVV+JHmgEwGIggwkNfBSigmjpb2imM7vAu21lOTGDxaRMLH4R3FGo1i lTKMZJjZwxE2lG+qOFMNRA0mvMEVZ954wcf7vaW+n6fZV906ulJabw7dkExl9KxBp44UeP NadJPIXxzES8ij2ao3sJleofaBFSAa0= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1695920428; a=rsa-sha256; cv=fail; b=DhtAk1j6QD9zbkIl+BfS39jGDFYRpFP77/b8mbIwjcdr/sF6YKsfSzstv3bnvbulE8YZko aptl0DwHmgPitUlHtMNqUKdZRtOjMuu8omQNhX+tHWOJ8AlRyo2r02g49abd9MOxET/2A0 GeMAVa8py2SSEj861mfaM23/JGAafq4= ARC-Authentication-Results: i=2; imf15.hostedemail.com; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b=6PsOF7lu; dkim=pass header.d=armh.onmicrosoft.com header.s=selector2-armh-onmicrosoft-com header.b=6PsOF7lu; spf=pass (imf15.hostedemail.com: domain of Szabolcs.Nagy@arm.com designates 40.107.8.52 as permitted sender) smtp.mailfrom=Szabolcs.Nagy@arm.com; dmarc=pass (policy=none) header.from=arm.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") 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=f+fE+7tV/oLB1Wx7LngAySEDb25Fz+qf9JsKa6Wgwp8=; b=6PsOF7luCBPMlVptpzby3woQ/x1Q7K/13iDsc8qjIRcwYf1ZXr5f+7qExo5A2e0HEot62nEkdOe/EJUmlla/AKTaAzP0+4E0l5eeLh7S4khdyh1H2DUOllc7G+sBv12E6GqOvtsoHpwcTFGtbCZ9zOkKm9P1DAVXaLTyJhnwUUI= Received: from DB7PR02CA0018.eurprd02.prod.outlook.com (2603:10a6:10:52::31) by PR3PR08MB5564.eurprd08.prod.outlook.com (2603:10a6:102:87::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6813.28; Thu, 28 Sep 2023 16:59:56 +0000 Received: from DBAEUR03FT064.eop-EUR03.prod.protection.outlook.com (2603:10a6:10:52:cafe::b7) by DB7PR02CA0018.outlook.office365.com (2603:10a6:10:52::31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6838.21 via Frontend Transport; Thu, 28 Sep 2023 16:59:56 +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 DBAEUR03FT064.mail.protection.outlook.com (100.127.143.3) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6838.25 via Frontend Transport; Thu, 28 Sep 2023 16:59:56 +0000 Received: ("Tessian outbound ee9c7f88acf7:v211"); Thu, 28 Sep 2023 16:59:56 +0000 X-CheckRecipientChecked: true X-CR-MTA-CID: 96bbd5875f488015 X-CR-MTA-TID: 64aa7808 Received: from ae34f44ea2b2.2 by 64aa7808-outbound-1.mta.getcheckrecipient.com id DD68AE92-8A84-41D5-A044-5FA316D72A35.1; Thu, 28 Sep 2023 16:59:45 +0000 Received: from EUR05-VI1-obe.outbound.protection.outlook.com by 64aa7808-outbound-1.mta.getcheckrecipient.com with ESMTPS id ae34f44ea2b2.2 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384); Thu, 28 Sep 2023 16:59:45 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=gBmkm46QyVYldy9Ay/rhgbsQXKf86a+euHSgGL2LoAIkhic2ej9dyfn2wUAueruhU7IY+sFPnl+ZI2j2LUZONgxjx4LFPejyxMGeqOz2hhzHM9JMQEwHDUOz2VWDp321oLeh+nEWpv/VwCSRnxceK+WlJ6nFX3Mf391Ij9draJnQaSK/DTGC73qZeZhexkGOyeG5DEBU2imN8G+v9occCZ97xl1jgo8toeJXJ0VU5BpdRHWuFNjfrT96rI7RemvJp6WvaPzyfY0S7Aq1bfKQAaG+B7ByutJgCHyN+VlK2PBmaXJUB6YgBFR15f7P/JYtkgtOoxPo5pwhpgiytEFAbQ== 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=f+fE+7tV/oLB1Wx7LngAySEDb25Fz+qf9JsKa6Wgwp8=; b=i+Szi7C/Xq30p8PSgo8TcGkAxUO1oLt9JHSHZyBvRMpxzpraE9ltkEOxaGwzYoHbADdTBtGH30eeUNyVNe8+VwmurIZUXSdXX9LV24q8kIUE1T2JrkCsGQlEMvrrDvQd1xAUj/gPKPf4MM7p2BbQH53O+NxKDETKWVwyks0hDeDD7YPM1u7Q5q/L5ysujiMLbuWOEIgO+N1sX9j9hVia2J20LHHz69QjMCBhxMRqfDFn8xysBDcKvtv41Av5j5qn3Jzf2KY4qC4eK8mL4cNDHmdZNZxxPVbNw2xSYwjOj0dcyx/a5LxiE7vgIf+BodKUtkV4aOGJ1Dccea9Z7OrRfQ== 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=f+fE+7tV/oLB1Wx7LngAySEDb25Fz+qf9JsKa6Wgwp8=; b=6PsOF7luCBPMlVptpzby3woQ/x1Q7K/13iDsc8qjIRcwYf1ZXr5f+7qExo5A2e0HEot62nEkdOe/EJUmlla/AKTaAzP0+4E0l5eeLh7S4khdyh1H2DUOllc7G+sBv12E6GqOvtsoHpwcTFGtbCZ9zOkKm9P1DAVXaLTyJhnwUUI= 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 AM8PR08MB6626.eurprd08.prod.outlook.com (2603:10a6:20b:367::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6838.21; Thu, 28 Sep 2023 16:59:41 +0000 Received: from DB9PR08MB7179.eurprd08.prod.outlook.com ([fe80::e34a:7a41:96db:8aba]) by DB9PR08MB7179.eurprd08.prod.outlook.com ([fe80::e34a:7a41:96db:8aba%4]) with mapi id 15.20.6813.027; Thu, 28 Sep 2023 16:59:41 +0000 Date: Thu, 28 Sep 2023 17:59:25 +0100 From: Szabolcs Nagy To: Catalin Marinas Cc: Mark Brown , 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: <20230807-arm64-gcs-v4-0-68cfa37f9069@kernel.org> <20230807-arm64-gcs-v4-3-68cfa37f9069@kernel.org> <43ec219d-bf20-47b8-a5f8-32bc3b64d487@sirena.org.uk> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: LNXP265CA0005.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:5e::17) To DB9PR08MB7179.eurprd08.prod.outlook.com (2603:10a6:10:2cc::19) MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: DB9PR08MB7179:EE_|AM8PR08MB6626:EE_|DBAEUR03FT064:EE_|PR3PR08MB5564:EE_ X-MS-Office365-Filtering-Correlation-Id: f30892ec-6c7d-49c7-d0ba-08dbc0445795 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: E3P97YBo0OgulrlE25F191cxETaPMCVoGGLqJVmqDz6j4DNz6A6D9/c+QRfEcx2bNqJI0qCqinF+71q9iMVyvvrXG9KQbMQ5ph0miQgx/Am2sP4u4hx295kc5QWbpYwdidi9/Dsp/iAtKx4nV4E1Kwat0KVEDaAq6ThuOsUJEondR+XB+2LR7KDenO2TN7dlZSVHCXVZBuCZnnB7O5UEK4RX82jRlOR9Xo2ARr7scIkVa51yYoAfHiZ2yy3iF57zsrKcRCY/oWVoEQwS/an+0LpxJCjX5iVyuPrMZAOvwrk+KCy9+ZxjPhNU4z+iakyEXIGD/Lu4LH9iEHbGFJF/VHUxK4MF4jKr7uCgBOYGB0rtQuyqanv3umRk/sZQl1AdxVIGGPM/w0uYbBHMIZAKvRUM/WpFRXFTP8BsZdWu25HbmkgP6HIpZy70FLcNktojhMCmnyDc/H6CBxkbgRw6eWyYLg4D+XqW76eYVhVr6AwCSMZwywBaePQVOIkXCcOaFYvtYUoB5WR5sFv1LgHgxmSZo9ImRyhQziDIiakvX2gF0jfrIwDahXhC3QP8eurX 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)(396003)(346002)(39860400002)(136003)(376002)(366004)(230922051799003)(451199024)(1800799009)(64100799003)(186009)(26005)(6512007)(316002)(66946007)(6636002)(2616005)(54906003)(41300700001)(66556008)(37006003)(66476007)(6862004)(8676002)(4326008)(8936002)(5660300002)(83380400001)(6486002)(38100700002)(478600001)(6666004)(6506007)(7416002)(2906002)(86362001)(36756003);DIR:OUT;SFP:1101; X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM8PR08MB6626 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: DBAEUR03FT064.eop-EUR03.prod.protection.outlook.com X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id-Prvs: 140f5b10-f0e6-4f3f-aae7-08dbc0444eaa 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)(39860400002)(136003)(396003)(376002)(346002)(230922051799003)(82310400011)(186009)(64100799003)(451199024)(1800799009)(40470700004)(46966006)(36840700001)(36756003)(86362001)(40480700001)(2906002)(2616005)(81166007)(316002)(41300700001)(54906003)(70206006)(6636002)(37006003)(6486002)(478600001)(6506007)(6666004)(5660300002)(6512007)(107886003)(83380400001)(40460700003)(8936002)(336012)(70586007)(4326008)(6862004)(8676002)(36860700001)(356005)(26005)(47076005)(82740400003);DIR:OUT;SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Sep 2023 16:59:56.2489 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: f30892ec-6c7d-49c7-d0ba-08dbc0445795 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: DBAEUR03FT064.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3PR08MB5564 X-Rspamd-Queue-Id: 5BD8BA0036 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: sk8rpz5enht5fpgoeuzi6ymqyetxza8a X-HE-Tag: 1695920427-203588 X-HE-Meta: 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 94PERQNn 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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 08/23/2023 14:11, Catalin Marinas wrote: > On Wed, Aug 23, 2023 at 11:09:59AM +0100, Szabolcs Nagy wrote: > > The 08/22/2023 18:53, Mark Brown wrote: > > > I do worry about the story for users calling the underlying clone3() API > > > (or legacy clone() for that matter) directly, and we would also need to > > > handle the initial GCS enable via prctl() - that's not insurmountable, > > > we could add a size argument there that only gets interpreted during the > > > initial enable for example. ... > > and there is user code doing raw clone threads (such threads are > > technically not allowed to call into libc) it's not immediately > > clear to me if having gcs in those threads is better or worse. i think raw clone / clone3 users may be relevant so we need a solution such that they don't fail when gcs args are missing. userspace allocated gcs works for me, but maybe the alternative with size only is more consistent (thread gcs is kernel mapped with fallback size logic if gcs size is missing): > An alternative would be for the clone3() to provide an address _hint_ > and size for GCS and it would still be the kernel doing the mmap (and > munmap on clearing). But at least the user has some control over the > placement of the GCS and its size (and maybe providing the address has > MAP_FIXED semantics). the main thread gcs is still special: the size is provided via prctl (if at all).