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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 94A63C4321A for ; Tue, 11 Jun 2019 17:50:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 47FC42086D for ; Tue, 11 Jun 2019 17:50:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47FC42086D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C08C96B000A; Tue, 11 Jun 2019 13:50:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BB9866B000D; Tue, 11 Jun 2019 13:50:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AA92A6B0010; Tue, 11 Jun 2019 13:50:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id 5E6D56B000A for ; Tue, 11 Jun 2019 13:50:47 -0400 (EDT) Received: by mail-ed1-f71.google.com with SMTP id d13so21779221edo.5 for ; Tue, 11 Jun 2019 10:50:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=VK15js9rOdFA81YfbRsGdiGRUgzc1A6qWvdMkzL0GsU=; b=gn8DYASqvHGZu8jFfFOT/ohC2rly54FPW6XpcmPpQXhlfIwpGG96d9k79mUA3Yg5AW NmtIuWWw3Jjr5Oi7WboJyKGBgJTzffEC/PN7ihllTxRxQirAtdEAEou5oRYCOGkXDqBs MX8pKzolR07QR8skxU6Gy4oCbM0zmXki7K8SmrcTp1RamRwHN7bql2y0Eiy2fPEHXgoI IShhKJySo4r73Pdz1bYoq/BoZ82USMfqtgSmxxjFxAl/xMa+JxzC73efl3BCMYYfysew WLlLHI1MCge3v+RIwP/UYdsctLFi2kEOyR8u153tIuKCb2RygpXuYwNo7mFF0eUdzQxv HabQ== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com X-Gm-Message-State: APjAAAVB3eKiF9nIh575OxvbYXQp/u0opIC9D/7c6L+2H4rf/3/DCJ9M RgPvaT/om3NaT9/rZZOnv0j/ui4UJZ5pDM7IiKpaK1qXoGd5PeU2hua90u4nX/mkzJZqrnOTNG4 MvTuQiBH3pORw0svGF/dtycKd4BzQWDE6GxAjrXv3ixlnkyqcPct1FTg0zFb1ECqhxA== X-Received: by 2002:a17:906:5846:: with SMTP id h6mr6802485ejs.200.1560275446945; Tue, 11 Jun 2019 10:50:46 -0700 (PDT) X-Google-Smtp-Source: APXvYqx/QnCx8uooFPZtKblRx8Yo/PxCMx50BXtcXDbvV0Z3CVBATA/spAzzYpezaHkHGtToo8F2 X-Received: by 2002:a17:906:5846:: with SMTP id h6mr6802439ejs.200.1560275446056; Tue, 11 Jun 2019 10:50:46 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1560275446; cv=none; d=google.com; s=arc-20160816; b=zHVaGoauXPNY4g1gjVLjUJ5LkeJCYebu517sKtqb0pIhsNjtJKp6fMPUdKDGUIH7// NV06t1vP45Z0dw5uNFLLCpohvOB3wFCF74pg2QScVaUT/2AEv1EISfofZOzFipTL0SOg 5LGl7PVf6vK7iOhgdRHcnYt/OXDUwZ0uHdg+V0cMDqMmhgpQgYlak5h/C6Oe2GINrcI1 +BniFniwQHrsXNcC5h8SuLnSb3RtFsYB1T4SXXhvtGE/ckh1hqckVsLg8ZzfzZ1JE+u9 rRc9kKYyWpwfWMKoFmyF8gfgc37B9oDz3Ibi0mJrFnmjqRztwgS1nn+BrVgFs+IIfEy0 V13Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=VK15js9rOdFA81YfbRsGdiGRUgzc1A6qWvdMkzL0GsU=; b=QfdBmSbNg4GEhs724s2KT9aNeHawbMtZYDZaggFIzrURByfwKCUbf9EP582sIux0ai 5OUbuC6AGGpYxG43srHaoQlrfIkkVdzl4+euHQpg72AprY63IJaX+1TCaeMAad/dYL6b FsKl/cmxZmSuj5yRDz9cyFC5FbpmCsKa+NGzxTzMLYPzPDgQargysRKrjpU9yrzcH/D7 NJnEu8BI8RTgRA5FmVGbEcqkLsTYODdjPsFqAa+GDiMDLhxT8eOVSqsnWFwp+X3A4pba Q890y3TVOZxNOWz/e4TjcIJVcb8WwXwZlkXlxwys95nR3oM230oecdcj0q4AGzoXExZk Oyzw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from foss.arm.com (foss.arm.com. [217.140.110.172]) by mx.google.com with ESMTP id r23si1179136ejj.297.2019.06.11.10.50.45 for ; Tue, 11 Jun 2019 10:50:46 -0700 (PDT) Received-SPF: pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) client-ip=217.140.110.172; Authentication-Results: mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1D236337; Tue, 11 Jun 2019 10:50:45 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 18BF83F73C; Tue, 11 Jun 2019 10:50:39 -0700 (PDT) Date: Tue, 11 Jun 2019 18:50:37 +0100 From: Catalin Marinas To: Andrey Konovalov Cc: Linux ARM , Linux Memory Management List , LKML , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , 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 Subject: Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel Message-ID: <20190611175037.pflr6q6ob67zjj25@mbp> References: <9e1b5998a28f82b16076fc85ab4f88af5381cf74.1559580831.git.andreyknvl@google.com> <20190611150122.GB63588@arrakis.emea.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) 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: On Tue, Jun 11, 2019 at 07:18:04PM +0200, Andrey Konovalov wrote: > On Tue, Jun 11, 2019 at 5:01 PM Catalin Marinas wrote: > > static void *tag_ptr(void *ptr) > > { > > static int tagged_addr_err = 1; > > unsigned long tag = 0; > > > > if (tagged_addr_err == 1) > > tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL, > > PR_TAGGED_ADDR_ENABLE, 0, 0, 0); > > I think this requires atomics. malloc() can be called from multiple threads. It's slightly racy but I assume in a real libc it can be initialised earlier than the hook calls while still in single-threaded mode (I had a quick attempt with __attribute__((constructor)) but didn't get far). Even with the race, under normal circumstances calling the prctl() twice is not a problem. I think the risk here is that someone disables the ABI via sysctl and the ABI is enabled for some of the threads only. -- Catalin