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[217.140.110.172]) by mx.google.com with ESMTP id i17si8525126ejc.55.2019.07.24.10.12.26 for ; Wed, 24 Jul 2019 10:12:27 -0700 (PDT) Received-SPF: pass (google.com: domain of vincenzo.frascino@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 vincenzo.frascino@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vincenzo.frascino@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 0E49528; Wed, 24 Jul 2019 10:12:26 -0700 (PDT) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3CE253F71F; Wed, 24 Jul 2019 10:12:21 -0700 (PDT) Subject: Re: [PATCH v19 00/15] arm64: untag user pointers passed to the kernel To: Will Deacon , Andrey Konovalov Cc: Will Deacon , Andrew Morton , Catalin Marinas , Mark Rutland , kvm@vger.kernel.org, Szabolcs Nagy , dri-devel@lists.freedesktop.org, Kostya Serebryany , Khalid Aziz , "open list:KERNEL SELFTEST FRAMEWORK" , Felix Kuehling , Jacob Bramley , Leon Romanovsky , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, Christoph Hellwig , Jason Gunthorpe , Linux ARM , Dave Martin , Evgeniy Stepanov , linux-media@vger.kernel.org, Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Ramana Radhakrishnan , Alex Williamson , Mauro Carvalho Chehab , Dmitry Vyukov , Linux Memory Management List , Greg Kroah-Hartman , Yishai Hadas , LKML , Jens Wiklander , Lee Smith , Alexander Deucher , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck References: <20190724140212.qzvbcx5j2gi5lcoj@willie-the-truck> <20190724142059.GC21234@fuggles.cambridge.arm.com> From: Vincenzo Frascino Message-ID: Date: Wed, 24 Jul 2019 18:12:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190724142059.GC21234@fuggles.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: Hi Will and Andrey, On 24/07/2019 15:20, Will Deacon wrote: > On Wed, Jul 24, 2019 at 04:16:49PM +0200, Andrey Konovalov wrote: >> On Wed, Jul 24, 2019 at 4:02 PM Will Deacon wrote: >>> On Tue, Jul 23, 2019 at 08:03:29PM +0200, Andrey Konovalov wrote: >>>> On Tue, Jul 23, 2019 at 7:59 PM Andrey Konovalov wrote: >>>>> >>>>> === Overview >>>>> >>>>> arm64 has a feature called Top Byte Ignore, which allows to embed pointer >>>>> tags into the top byte of each pointer. Userspace programs (such as >>>>> HWASan, a memory debugging tool [1]) might use this feature and pass >>>>> tagged user pointers to the kernel through syscalls or other interfaces. >>>>> >>>>> Right now the kernel is already able to handle user faults with tagged >>>>> pointers, due to these patches: >>>>> >>>>> 1. 81cddd65 ("arm64: traps: fix userspace cache maintenance emulation on a >>>>> tagged pointer") >>>>> 2. 7dcd9dd8 ("arm64: hw_breakpoint: fix watchpoint matching for tagged >>>>> pointers") >>>>> 3. 276e9327 ("arm64: entry: improve data abort handling of tagged >>>>> pointers") >>>>> >>>>> This patchset extends tagged pointer support to syscall arguments. >>> >>> [...] >>> >>>> Do you think this is ready to be merged? >>>> >>>> Should this go through the mm or the arm tree? >>> >>> I would certainly prefer to take at least the arm64 bits via the arm64 tree >>> (i.e. patches 1, 2 and 15). We also need a Documentation patch describing >>> the new ABI. >> >> Sounds good! Should I post those patches together with the >> Documentation patches from Vincenzo as a separate patchset? > > Yes, please (although as you say below, we need a new version of those > patches from Vincenzo to address the feedback on v5). The other thing I > should say is that I'd be happy to queue the other patches in the series > too, but some of them are missing acks from the relevant maintainers (e.g. > the mm/ and fs/ changes). > I am actively working on the document and will share v6 with the requested changes in the next few days. > Will > -- Regards, Vincenzo