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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_SANE_1 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 3785CC4363D for ; Tue, 22 Sep 2020 15:55:03 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 ABF092399A for ; Tue, 22 Sep 2020 15:55:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BjDFOCpA"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armh.onmicrosoft.com header.i=@armh.onmicrosoft.com header.b="ya6s8sec"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armh.onmicrosoft.com header.i=@armh.onmicrosoft.com header.b="ya6s8sec" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ABF092399A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MLR1ZbC/hlEncpHuC98u2m6U0I5AeXAjabClcfypaA0=; b=BjDFOCpAZjxdQr7smNijGiqkU N44kkJx9piili5A206TrVCVJoVTm8EG4mOuSa4uaW7QrHg2Jy/A6oLllcniYGOQtjGLf7tkx6lQY8 Z18C2YFrYLIpztqkgNmUwcN8jJxositiDsr68IcR3PmNOVaLNjENuejQCEBsnQUC+Th3+SyXa8xe3 jGQpT0TO3xSHXMoELwMKNGGwElBIWkLtLdqwre1/KZrB1G+BuZLx3sMJBnW11IapE+X0+f69NNk+b p9M6jWOiGrsDh4DwL9CDPahp3+ko5vfS4BUUMs8IoxVfBelXzuXNgmz5SnN7LK4/M0FkhkKMQToyh CjXzhLQVg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKkbb-0007BV-Uh; Tue, 22 Sep 2020 15:53:24 +0000 Received: from mail-vi1eur05on2079.outbound.protection.outlook.com ([40.107.21.79] helo=EUR05-VI1-obe.outbound.protection.outlook.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKkbM-00078Q-Kk for linux-arm-kernel@lists.infradead.org; Tue, 22 Sep 2020 15:53:10 +0000 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=TNlMc3BfSCHBfmvuHxysUdTHrqLsanEl/lgUOtkyrZI=; b=ya6s8secKJnUuPrqMD57mof50sK8ubEu/bFd/qXrCcIT1zdTW+sS9vlWnxHvstA5rXtPNtZsKhPU81VzCr5gG6aZ1Y/0K1WuHMLCXYRSUGZwnMlhn4AwTGoiDOiJT8bJcJK6p9kHQJsSW9+4JvgK3Fg9oAI+UENQGf+50IxjobM= Received: from AM6P193CA0143.EURP193.PROD.OUTLOOK.COM (2603:10a6:209:85::48) by VE1PR08MB5262.eurprd08.prod.outlook.com (2603:10a6:803:106::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3391.15; Tue, 22 Sep 2020 15:53:00 +0000 Received: from VE1EUR03FT046.eop-EUR03.prod.protection.outlook.com (2603:10a6:209:85:cafe::64) by AM6P193CA0143.outlook.office365.com (2603:10a6:209:85::48) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3391.14 via Frontend Transport; Tue, 22 Sep 2020 15:53:00 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 63.35.35.123) smtp.mailfrom=arm.com; lists.infradead.org; dkim=pass (signature was verified) header.d=armh.onmicrosoft.com;lists.infradead.org; dmarc=bestguesspass 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; Received: from 64aa7808-outbound-1.mta.getcheckrecipient.com (63.35.35.123) by VE1EUR03FT046.mail.protection.outlook.com (10.152.19.226) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3391.15 via Frontend Transport; Tue, 22 Sep 2020 15:52:59 +0000 Received: ("Tessian outbound 195a290eb161:v64"); Tue, 22 Sep 2020 15:52:59 +0000 X-CheckRecipientChecked: true X-CR-MTA-CID: f6ed8c82c5e227ec X-CR-MTA-TID: 64aa7808 Received: from 8ce197089d28.1 by 64aa7808-outbound-1.mta.getcheckrecipient.com id 42BC8765-7AE1-4912-8B77-5AF8C51E68DD.1; Tue, 22 Sep 2020 15:52:54 +0000 Received: from EUR03-VE1-obe.outbound.protection.outlook.com by 64aa7808-outbound-1.mta.getcheckrecipient.com with ESMTPS id 8ce197089d28.1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384); Tue, 22 Sep 2020 15:52:54 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=hknS0N+UtDSYG5AEf1YZLG8h9JMtq2cDG+DKb36u1pgfc7Cma276SApH8hFD3nwko90I/hGXRlsPwTXT8M5O+TKacQEXPiBN/kibBDnRpWOl+w9IRbd/v8oJ/1YuYj9iI1Kn1sAHA03Ilwm9CAvyIiya4nY5y1kWl2V8gogaaTNMPvsduefyElcl9kuHGW0UrLNWISfmp/CQ10Ex+UPpEZT+zzOlcAZbmoD940UKupsVeULswCIGcsRlZ3d2R8XAjQURYSZrhTR8Uzw/r7Jjh9EwVvWEHe7P6ed5Oq+PP/MjCUfH5WH3o1L5kDkDDq/n6Y8PuN/gm54wVz6SWKJO6g== 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-SenderADCheck; bh=TNlMc3BfSCHBfmvuHxysUdTHrqLsanEl/lgUOtkyrZI=; b=Hg3PRNOUUphhK8HOqsnMhQRIxHYp7jepRztn0AV4/5vHu1zWAJBSzsxhrMJzpL9txcFzXOWNKC40tHQwtJKwb81oiRCCyr1bLDThHHFszUvTuNEi9GE8yAASe49PZDfHZnQTlLkw8I8xsUam0xeBNDdBx+UI8HFatPTXAKk2oJOLSQBKr7xrBXSXr2+RFpclkxmkGNQAXDR2O/kURphLffromeu9qZkyayGFdufyYBr/SjbEx5jM+/1/bBVf/KgssDbL43MX72y+020vyL3nGQbYZqTot/NvPmEmJIY8vx29sF0bTQhutRN65xjSWDzf4kTKZVkXJu2FfjOONUw3HQ== 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=TNlMc3BfSCHBfmvuHxysUdTHrqLsanEl/lgUOtkyrZI=; b=ya6s8secKJnUuPrqMD57mof50sK8ubEu/bFd/qXrCcIT1zdTW+sS9vlWnxHvstA5rXtPNtZsKhPU81VzCr5gG6aZ1Y/0K1WuHMLCXYRSUGZwnMlhn4AwTGoiDOiJT8bJcJK6p9kHQJsSW9+4JvgK3Fg9oAI+UENQGf+50IxjobM= Authentication-Results-Original: arm.com; dkim=none (message not signed) header.d=none;arm.com; dmarc=none action=none header.from=arm.com; Received: from PR3PR08MB5564.eurprd08.prod.outlook.com (2603:10a6:102:87::18) by PR3PR08MB5563.eurprd08.prod.outlook.com (2603:10a6:102:89::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3412.20; Tue, 22 Sep 2020 15:52:51 +0000 Received: from PR3PR08MB5564.eurprd08.prod.outlook.com ([fe80::ad67:3b31:680d:9d01]) by PR3PR08MB5564.eurprd08.prod.outlook.com ([fe80::ad67:3b31:680d:9d01%3]) with mapi id 15.20.3391.027; Tue, 22 Sep 2020 15:52:51 +0000 Date: Tue, 22 Sep 2020 16:52:49 +0100 From: Szabolcs Nagy To: Catalin Marinas Subject: Re: [PATCH v9 29/29] arm64: mte: Add Memory Tagging Extension documentation Message-ID: <20200922155248.GA16385@arm.com> References: <20200904103029.32083-1-catalin.marinas@arm.com> <20200904103029.32083-30-catalin.marinas@arm.com> <20200917081107.GA29031@willie-the-truck> <20200917090229.GA10662@gaia> Content-Disposition: inline In-Reply-To: <20200917090229.GA10662@gaia> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: LO2P265CA0091.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:8::31) To PR3PR08MB5564.eurprd08.prod.outlook.com (2603:10a6:102:87::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from arm.com (217.140.106.54) by LO2P265CA0091.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:8::31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3391.14 via Frontend Transport; Tue, 22 Sep 2020 15:52:51 +0000 X-Originating-IP: [217.140.106.54] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: dcc33280-d042-494e-71d6-08d85f0f94e7 X-MS-TrafficTypeDiagnostic: PR3PR08MB5563:|VE1PR08MB5262: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: x-checkrecipientrouted: true NoDisclaimer: true X-MS-Oob-TLC-OOBClassifiers: OLM:8882;OLM:8882; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam-Untrusted: BCL:0; X-Microsoft-Antispam-Message-Info-Original: 6pgZPDuq6+dE03Ok39pzE1S12bxKbSkjBRrdHBJMkV8h6oEEMl7opsxDcsV9speEYDHkDcVtPzoFGNBXz+VnZE0J2WTRAC4yrqS08bEmwbSoB+5iFqkR5OrgHVijgeRPC5tlJITRN5XwMtx81e+ZfqX+N32FZ1PW+M10B255zL3Zs1bRpBm3/8Ou3sQ0KgYCtY/okQ5uOV6VtaqAl4c+IK2cdbMXdX7YkrCRXJ8ypWx0sfOoH7GSQTrQn1tydvTOLIyos9BMWVeefCsgOX6nKuwQSwUZxG75DINAc2B9dxaIfi+cCbpgcvIKjh3rBdNcD0I28y7ka0GhjkIx3lW7/w== X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:PR3PR08MB5564.eurprd08.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(396003)(366004)(39850400004)(346002)(376002)(136003)(16526019)(6636002)(33656002)(86362001)(956004)(2616005)(478600001)(8936002)(26005)(7696005)(52116002)(83380400001)(5660300002)(54906003)(6862004)(8676002)(8886007)(44832011)(55016002)(4326008)(66556008)(186003)(316002)(37006003)(66476007)(66946007)(2906002)(1076003)(36756003); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3PR08MB5563 Original-Authentication-Results: arm.com; dkim=none (message not signed) header.d=none;arm.com; dmarc=none action=none header.from=arm.com; X-EOPAttributedMessage: 0 X-MS-Exchange-Transport-CrossTenantHeadersStripped: VE1EUR03FT046.eop-EUR03.prod.protection.outlook.com X-MS-Office365-Filtering-Correlation-Id-Prvs: b3c98b4d-fc1c-4bdf-b8d1-08d85f0f8fbe X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: ihHCA0p7gLOFbFXY7aui2pFEOQKzpyyU/D/i54FNvqzXg+l8gfVhU5z/Ry4rlkqyHXV5FNFX/XhEScH6AgISU4wGNykA85yvO6jR7vksDUfOuxTwru7aR3o9zm8QzJnXyjsUN6ERTiPEtBH60Zc/Dx/oqiLt602Ed/CmmcqYGyu9yGt7pvRaKYiK0yV7uhkrBLpClOYGtbkGkPp7ulQlJ41UlOXgXzzbJstts7kVCdFbKJddv4JS06rJqRGlw1P3vRLzcQRbbr7eMYxIfaXD+TCqnUCPUCczruYIFF4/KvItmikS1WgSxRtICUpWJgde2Sv8k/AXd8Y+YQj4SIg7rgWdJbWlqcNzOBUkObwv6ZN3GU9noPAeMaZEgd7joW/dBhvFEiu/kUxAfXb4mTAyodZ6SJABJ0EktgXx/8Kw0c2i1CfJgo5WlSS5tWhSH3ZS 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:(4636009)(396003)(39850400004)(346002)(136003)(376002)(46966005)(33656002)(316002)(36756003)(83380400001)(1076003)(478600001)(70586007)(8936002)(6636002)(70206006)(44832011)(2906002)(47076004)(37006003)(336012)(4326008)(6862004)(2616005)(5660300002)(956004)(82740400003)(26005)(356005)(55016002)(7696005)(8886007)(107886003)(8676002)(186003)(16526019)(86362001)(54906003)(36906005)(82310400003)(81166007); DIR:OUT; SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Sep 2020 15:52:59.9089 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dcc33280-d042-494e-71d6-08d85f0f94e7 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: VE1EUR03FT046.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: VE1PR08MB5262 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200922_115308_747750_521EB221 X-CRM114-Status: GOOD ( 25.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, libc-alpha@sourceware.org, Peter Collingbourne , Andrey Konovalov , Kevin Brodsky , linux-mm@kvack.org, Andrew Morton , Vincenzo Frascino , Will Deacon , Dave P Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The 09/17/2020 10:02, Catalin Marinas wrote: > On Thu, Sep 17, 2020 at 09:11:08AM +0100, Will Deacon wrote: > > On Fri, Sep 04, 2020 at 11:30:29AM +0100, Catalin Marinas wrote: > > > From: Vincenzo Frascino ... > > > Acked-by: Szabolcs Nagy > > > > I'm taking this to mean that Szabolcs is happy with the proposed ABI -- > > please shout if that's not the case! > > I think Szabolcs is still on holiday. To summarise the past threads, > AFAICT he's happy with this per-thread control ABI but the discussion > went on whether to expand it in the future (with a new bit) to > synchronise the tag checking mode across all threads of a process. This > adds some complications for the kernel as it needs an IPI to the other > CPUs to set SCTLR_EL1 and it's also racy with multiple threads > requesting different modes. > > Now, in the glibc land, if the tag check mode is controlled via > environment variables, the dynamic loader can set this at process start > while still in single-threaded mode and not touch it at run-time. The > MTE checking can still be enabled at run-time, per mapped memory range > via the PROT_MTE flag. This approach doesn't require any additional > changes to the current patches. But it's for Szabolcs to confirm once > he's back. my thinking now is that for PROT_MTE use outside of libc we will need a way to enable tag checks early so user code does not have to worry about tag check settings across threads (coordinating the setting at runtime seems problematic, same for the irg exclusion set). if we add a kernel level opt-in mechanism for tag checks later (e.g. elf marking) or if the settings are exclusively owned by early libc code then i think the proposed abi is ok (this is our current agreement and works as long as no late runtime change is needed to the settings). i'm now wondering about the default tag check mode: it may be better to enable sync tag checks in the kernel. it's not clear to me what would break with that. this is probably late to discuss now and libc would need ways to override the default no matter what, but i'd like to know if somebody sees problems or risks with unconditional sync tag checks turned on (sorry i don't remember if we went through this before). i assume it would have no effect on a process that never uses PROT_MTE. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel