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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 AE9FEC32751 for ; Wed, 31 Jul 2019 17:05:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B0E321852 for ; Wed, 31 Jul 2019 17:05:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730506AbfGaRFR (ORCPT ); Wed, 31 Jul 2019 13:05:17 -0400 Received: from mga03.intel.com ([134.134.136.65]:44648 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726491AbfGaRFQ (ORCPT ); Wed, 31 Jul 2019 13:05:16 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 31 Jul 2019 10:05:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,330,1559545200"; d="scan'208";a="183757949" Received: from ray.jf.intel.com (HELO [10.7.201.140]) ([10.7.201.140]) by orsmga002.jf.intel.com with ESMTP; 31 Jul 2019 10:05:15 -0700 Subject: Re: [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI To: Andrey Konovalov , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Catalin Marinas , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh , Jason Gunthorpe , Christoph Hellwig , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Kevin Brodsky , Szabolcs Nagy References: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 7/23/19 10:58 AM, Andrey Konovalov wrote: > +long set_tagged_addr_ctrl(unsigned long arg) > +{ > + if (!tagged_addr_prctl_allowed) > + return -EINVAL; > + if (is_compat_task()) > + return -EINVAL; > + if (arg & ~PR_TAGGED_ADDR_ENABLE) > + return -EINVAL; > + > + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); > + > + return 0; > +} Instead of a plain enable/disable, a more flexible ABI would be to have the tag mask be passed in. That way, an implementation that has a flexible tag size can select it. It also ensures that userspace actually knows what the tag size is and isn't surprised if a hardware implementation changes the tag size or position. Also, this whole set deals with tagging/untagging, but there's an effective loss of address space when you do this. Is that dealt with anywhere? How do we ensure that allocations don't get placed at a tagged address before this gets turned on? Where's that checking? 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 1D8A2C433FF for ; Wed, 31 Jul 2019 17:05:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E52A421852 for ; Wed, 31 Jul 2019 17:05:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="o9ZRteaz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E52A421852 Authentication-Results: mail.kernel.org; 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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hss2n-0000Sd-JF; Wed, 31 Jul 2019 17:05:41 +0000 Received: from mga12.intel.com ([192.55.52.136]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hss2X-0000Qy-40 for linux-arm-kernel@lists.infradead.org; Wed, 31 Jul 2019 17:05:26 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 31 Jul 2019 10:05:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,330,1559545200"; d="scan'208";a="183757949" Received: from ray.jf.intel.com (HELO [10.7.201.140]) ([10.7.201.140]) by orsmga002.jf.intel.com with ESMTP; 31 Jul 2019 10:05:15 -0700 Subject: Re: [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI To: Andrey Konovalov , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org References: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190731_100525_191663_B83725C8 X-CRM114-Status: GOOD ( 13.60 ) 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: Mark Rutland , Szabolcs Nagy , Catalin Marinas , Will Deacon , Kostya Serebryany , Khalid Aziz , Felix Kuehling , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , Christoph Hellwig , Jason Gunthorpe , Dave Martin , Evgeniy Stepanov , Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Ramana Radhakrishnan , Alex Williamson , Mauro Carvalho Chehab , Dmitry Vyukov , Greg Kroah-Hartman , Yishai Hadas , Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/23/19 10:58 AM, Andrey Konovalov wrote: > +long set_tagged_addr_ctrl(unsigned long arg) > +{ > + if (!tagged_addr_prctl_allowed) > + return -EINVAL; > + if (is_compat_task()) > + return -EINVAL; > + if (arg & ~PR_TAGGED_ADDR_ENABLE) > + return -EINVAL; > + > + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); > + > + return 0; > +} Instead of a plain enable/disable, a more flexible ABI would be to have the tag mask be passed in. That way, an implementation that has a flexible tag size can select it. It also ensures that userspace actually knows what the tag size is and isn't surprised if a hardware implementation changes the tag size or position. Also, this whole set deals with tagging/untagging, but there's an effective loss of address space when you do this. Is that dealt with anywhere? How do we ensure that allocations don't get placed at a tagged address before this gets turned on? Where's that checking? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Date: Wed, 31 Jul 2019 10:05:15 -0700 Message-ID: <7a34470c-73f0-26ac-e63d-161191d4b1e4@intel.com> References: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Andrey Konovalov , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Catalin Marinas , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh List-Id: dri-devel@lists.freedesktop.org On 7/23/19 10:58 AM, Andrey Konovalov wrote: > +long set_tagged_addr_ctrl(unsigned long arg) > +{ > + if (!tagged_addr_prctl_allowed) > + return -EINVAL; > + if (is_compat_task()) > + return -EINVAL; > + if (arg & ~PR_TAGGED_ADDR_ENABLE) > + return -EINVAL; > + > + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); > + > + return 0; > +} Instead of a plain enable/disable, a more flexible ABI would be to have the tag mask be passed in. That way, an implementation that has a flexible tag size can select it. It also ensures that userspace actually knows what the tag size is and isn't surprised if a hardware implementation changes the tag size or position. Also, this whole set deals with tagging/untagging, but there's an effective loss of address space when you do this. Is that dealt with anywhere? How do we ensure that allocations don't get placed at a tagged address before this gets turned on? Where's that checking?