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[217.140.101.70]) by mx.google.com with ESMTP id f58si209378edf.183.2019.05.23.13.11.20 for ; Thu, 23 May 2019 13:11:20 -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 1A48EA78; Thu, 23 May 2019 13:11:19 -0700 (PDT) Received: from mbp (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BBB143F690; Thu, 23 May 2019 13:11:12 -0700 (PDT) Date: Thu, 23 May 2019 21:11:05 +0100 From: Catalin Marinas To: Khalid Aziz Cc: Kees Cook , Evgenii Stepanov , Andrey Konovalov , 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 Subject: Re: [PATCH v15 00/17] arm64: untag user pointers passed to the kernel Message-ID: <20190523201105.oifkksus4rzcwqt4@mbp> References: <20190517144931.GA56186@arrakis.emea.arm.com> <20190521182932.sm4vxweuwo5ermyd@mbp> <201905211633.6C0BF0C2@keescook> <6049844a-65f5-f513-5b58-7141588fef2b@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6049844a-65f5-f513-5b58-7141588fef2b@oracle.com> 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: Hi Khalid, On Thu, May 23, 2019 at 11:51:40AM -0600, Khalid Aziz wrote: > On 5/21/19 6:04 PM, Kees Cook wrote: > > As an aside: I think Sparc ADI support in Linux actually side-stepped > > this[1] (i.e. chose "solution 1"): "All addresses passed to kernel must > > be non-ADI tagged addresses." (And sadly, "Kernel does not enable ADI > > for kernel code.") I think this was a mistake we should not repeat for > > arm64 (we do seem to be at least in agreement about this, I think). > > > > [1] https://lore.kernel.org/patchwork/patch/654481/ > > That is a very early version of the sparc ADI patch. Support for tagged > addresses in syscalls was added in later versions and is in the patch > that is in the kernel. I tried to figure out but I'm not familiar with the sparc port. How did you solve the tagged address going into various syscall implementations in the kernel (e.g. sys_write)? Is the tag removed on kernel entry or it ends up deeper in the core code? Thanks. -- Catalin