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[217.140.110.172]) by mx.google.com with ESMTP id v26si7923084eju.206.2019.07.24.07.21.07 for ; Wed, 24 Jul 2019 07:21:07 -0700 (PDT) Received-SPF: pass (google.com: domain of will.deacon@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 will.deacon@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=will.deacon@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 4AFA328; Wed, 24 Jul 2019 07:21:06 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 761323F71A; Wed, 24 Jul 2019 07:21:01 -0700 (PDT) Date: Wed, 24 Jul 2019 15:20:59 +0100 From: Will Deacon To: Andrey Konovalov Cc: Will Deacon , Vincenzo Frascino , 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 Subject: Re: [PATCH v19 00/15] arm64: untag user pointers passed to the kernel Message-ID: <20190724142059.GC21234@fuggles.cambridge.arm.com> References: <20190724140212.qzvbcx5j2gi5lcoj@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () 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 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). Will