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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 2D9C1C28CC2 for ; Fri, 31 May 2019 16:20:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BC63526BE0 for ; Fri, 31 May 2019 16:20:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC63526BE0 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 3EBF66B0010; Fri, 31 May 2019 12:20:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3763C6B026B; Fri, 31 May 2019 12:20:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 23D776B026C; Fri, 31 May 2019 12:20:07 -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 CB02C6B0010 for ; Fri, 31 May 2019 12:20:06 -0400 (EDT) Received: by mail-ed1-f71.google.com with SMTP id y24so14567495edb.1 for ; Fri, 31 May 2019 09:20:06 -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=p5rQBXnOETFoaoADzLwPGcefz0MOaI/LmtU9nK58nmI=; b=iyE/hCe5P4k++z7KKjwGPxEkIp6nPSMR1VMprsqPNJ0OV4wTQ4eFWtq6StSt9UcEDQ dWManolNfAVavsXsdc8Nh5HnctI2kWwoNxPxwKQzhGGYyVR3wlWZndddkCCG/7Dmv0Rh rknsfCIA0bZ9QpmzUMSEQOX/rS+9HKNd91vNWGp75bH0OGXRp+5xhYeO2xqOmilNYNlF CBZVGIUIHqYVxIVI8p7Y2iP/EHFKJkofy6ipgBbjYLwNF6YAg5/yQr5FJ6YWCpMcLFNh NDUu7Wz5SrseK2goZ74MtyzjbWuOWur+sN93DyWXfSHyaNZi+CrEtjy7B/IXut5xjNt7 FJ9A== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com X-Gm-Message-State: APjAAAV2QuUZsxCZCv4UzopYOjuHofLYU/+dRavyX1LXFrqfLzYikgMi 9zQTJCWe2deZi1vxbqKYs2LVE+GKLEsDcBNnkw2DM9liAd4SmEKhjPcn7CMCZykF9as6r+ouBWR TJuznJ/QgIZ38Pl+Pq5bAyo1vjYHBn7erHTf7aUp2/H38Xs6ccP3M+if1/dY4uAflqQ== X-Received: by 2002:a17:906:1502:: with SMTP id b2mr8812135ejd.284.1559319606369; Fri, 31 May 2019 09:20:06 -0700 (PDT) X-Google-Smtp-Source: APXvYqwgKDX/sl/KCKRITlB5MhGd6mYjQ9M5R7gLovwDjmyt2/uT2O8JzuwXYvT8qJd4mrK9JjZS X-Received: by 2002:a17:906:1502:: with SMTP id b2mr8812007ejd.284.1559319605128; Fri, 31 May 2019 09:20:05 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1559319605; cv=none; d=google.com; s=arc-20160816; b=vnzLatuFpb3EL6freuOCee9xefi4HALhUZgrDxmPST8htXiLH/0J4l3swa2G7cER3O 4vkZpWYyE6xnMyQBqOFS9uyjSMJGEO62YJ65XXrM4mWw8FvIpRM8qqfFN8TtV4XijdLE fgIgSdYnhrhSfg+FWt3OV0T/aLYIgZYX42jGCXCqnRO8spPtd3o4Ma7oux9dgj8LG05i 9ThS6gDRyyyKEm12Ml3ek5JF1ODv/5RbBInU+m7nhBIh2DK5jjtQm8kCxTus612fisHE fziVq6mCNiyOGSMIZ5u63Gpr4IKPTeOq6l9DRjjqEZPA+JX/Yo3p4FZfikQh2i667vRy PDCw== 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=p5rQBXnOETFoaoADzLwPGcefz0MOaI/LmtU9nK58nmI=; b=zmzovhKsis/wKFJr7lHPYfArLRe21wKz/V8lfdQBhWAku6pep6Tuyl45U5tQDNxiLT KBft57CY5jkgGGgteSMO2DiIIGgnHZeN8KaiLjahQIAP8QQ0NJvC7pUf8R3n6ZDh//yy cpOXwfQWaWe3YVYixYKouHs+eIBPSeBR1zEQ+AcxQWvhK4pSE8WnhjoC5PlgPwAHbzJQ kveCsoDsXyXyuWLSnmCxKQyXcBTZ0chfRQMpJZgKvtRWPCYj755mdKzOeWpF0fkqbLex O2yJyqFv4zrVF99ul3xjY3As9niIhNgz1z9gA2CRhKlgE0MIWKlS6uG526RxYzpehh9p fKIQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id qo11si4149486ejb.41.2019.05.31.09.20.04 for ; Fri, 31 May 2019 09:20:05 -0700 (PDT) Received-SPF: pass (google.com: domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9E486341; Fri, 31 May 2019 09:20:03 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B67CE3F59C; Fri, 31 May 2019 09:19:57 -0700 (PDT) Date: Fri, 31 May 2019 17:19:55 +0100 From: Catalin Marinas To: Andrey Konovalov Cc: Kees Cook , Evgenii Stepanov , 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 , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Elliott Hughes , Khalid Aziz Subject: Re: [PATCH v15 00/17] arm64: untag user pointers passed to the kernel Message-ID: <20190531161954.GA3568@arrakis.emea.arm.com> References: <20190521182932.sm4vxweuwo5ermyd@mbp> <201905211633.6C0BF0C2@keescook> <6049844a-65f5-f513-5b58-7141588fef2b@oracle.com> <20190523201105.oifkksus4rzcwqt4@mbp> <20190524101139.36yre4af22bkvatx@mbp> <20190530171540.GD35418@arrakis.emea.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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 Fri, May 31, 2019 at 04:29:10PM +0200, Andrey Konovalov wrote: > On Thu, May 30, 2019 at 7:15 PM Catalin Marinas wrote: > > On Tue, May 28, 2019 at 04:14:45PM +0200, Andrey Konovalov wrote: > > > Thanks for a lot of valuable input! I've read through all the replies > > > and got somewhat lost. What are the changes I need to do to this > > > series? > > > > > > 1. Should I move untagging for memory syscalls back to the generic > > > code so other arches would make use of it as well, or should I keep > > > the arm64 specific memory syscalls wrappers and address the comments > > > on that patch? > > > > Keep them generic again but make sure we get agreement with Khalid on > > the actual ABI implications for sparc. > > OK, will do. I find it hard to understand what the ABI implications > are. I'll post the next version without untagging in brk, mmap, > munmap, mremap (for new_address), mmap_pgoff, remap_file_pages, shmat > and shmdt. It's more about not relaxing the ABI to accept non-zero top-byte unless we have a use-case for it. For mmap() etc., I don't think that's needed but if you think otherwise, please raise it. > > > 2. Should I make untagging opt-in and controlled by a command line argument? > > > > Opt-in, yes, but per task rather than kernel command line option. > > prctl() is a possibility of opting in. > > OK. Should I store a flag somewhere in task_struct? Should it be > inheritable on clone? A TIF flag would do but I'd say leave it out for now (default opted in) until we figure out the best way to do this (can be a patch on top of this series). Thanks. -- Catalin