From mboxrd@z Thu Jan 1 00:00:00 1970 From: Khalid Aziz Subject: Re: [PATCH v2] sparc64: Add support for Application Data Integrity (ADI) Date: Mon, 7 Mar 2016 11:39:15 -0700 Message-ID: <56DDCAD3.3090106@oracle.com> References: <1456951177-23579-1-git-send-email-khalid.aziz@oracle.com> <20160305.230702.1325379875282120281.davem@davemloft.net> <56DD9949.1000106@oracle.com> <56DD9E94.70201@oracle.com> <56DDA6FD.4040404@oracle.com> <56DDBE68.6080709@linux.intel.com> <56DDC47C.8010206@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56DDC47C.8010206@linux.intel.com> Sender: owner-linux-mm@kvack.org To: Dave Hansen , Andy Lutomirski Cc: Rob Gardner , David Miller , Jonathan Corbet , Andrew Morton , dingel@linux.vnet.ibm.com, bob.picco@oracle.com, "Kirill A. Shutemov" , "Aneesh Kumar K.V" , Andrea Arcangeli , Arnd Bergmann , sparclinux@vger.kernel.org, Michal Hocko , chris.hyser@oracle.com, Richard Weinberger , Vlastimil Babka , Konstantin Khlebnikov , Oleg Nesterov , Greg Thelen , Jan Kara , xiexiuqi@huawei.com, Vineet.Gupta1@synopsys.com, Andrew Lutomirski , "Eric W. Biederman" List-Id: linux-arch.vger.kernel.org On 03/07/2016 11:12 AM, Dave Hansen wrote: > On 03/07/2016 09:53 AM, Andy Lutomirski wrote: >> Also, what am I missing? Tying these tags to the physical page seems >> like a poor design to me. This seems really awkward to use. > > Yeah, can you describe the structures that store these things? Surely > the hardware has some kind of lookup tables for them and stores them in > memory _somewhere_. > Version tags are tied to virtual addresses, not physical pages. Where exactly are the tags stored is part of processor architecture and I am not privy to that. MMU stores these lookup tables somewhere and uses it to authenticate access to virtual addresses. It really is irrelevant to kernel how MMU implements access controls as long as we have access to the knowledge of how to use it. Thanks, Khalid -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:26734 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752082AbcCGSkd (ORCPT ); Mon, 7 Mar 2016 13:40:33 -0500 Subject: Re: [PATCH v2] sparc64: Add support for Application Data Integrity (ADI) References: <1456951177-23579-1-git-send-email-khalid.aziz@oracle.com> <20160305.230702.1325379875282120281.davem@davemloft.net> <56DD9949.1000106@oracle.com> <56DD9E94.70201@oracle.com> <56DDA6FD.4040404@oracle.com> <56DDBE68.6080709@linux.intel.com> <56DDC47C.8010206@linux.intel.com> From: Khalid Aziz Message-ID: <56DDCAD3.3090106@oracle.com> Date: Mon, 7 Mar 2016 11:39:15 -0700 MIME-Version: 1.0 In-Reply-To: <56DDC47C.8010206@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dave Hansen , Andy Lutomirski Cc: Rob Gardner , David Miller , Jonathan Corbet , Andrew Morton , dingel@linux.vnet.ibm.com, bob.picco@oracle.com, "Kirill A. Shutemov" , "Aneesh Kumar K.V" , Andrea Arcangeli , Arnd Bergmann , sparclinux@vger.kernel.org, Michal Hocko , chris.hyser@oracle.com, Richard Weinberger , Vlastimil Babka , Konstantin Khlebnikov , Oleg Nesterov , Greg Thelen , Jan Kara , xiexiuqi@huawei.com, Vineet.Gupta1@synopsys.com, Andrew Lutomirski , "Eric W. Biederman" , bsegall@google.com, Geert Uytterhoeven , Davidlohr Bueso , Alexey Dobriyan , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , linux-arch , Linux API Message-ID: <20160307183915.ny-2xUmXcVJzK0M1Qx2kBg9fJgYlq2zoQgJePIS8sk8@z> On 03/07/2016 11:12 AM, Dave Hansen wrote: > On 03/07/2016 09:53 AM, Andy Lutomirski wrote: >> Also, what am I missing? Tying these tags to the physical page seems >> like a poor design to me. This seems really awkward to use. > > Yeah, can you describe the structures that store these things? Surely > the hardware has some kind of lookup tables for them and stores them in > memory _somewhere_. > Version tags are tied to virtual addresses, not physical pages. Where exactly are the tags stored is part of processor architecture and I am not privy to that. MMU stores these lookup tables somewhere and uses it to authenticate access to virtual addresses. It really is irrelevant to kernel how MMU implements access controls as long as we have access to the knowledge of how to use it. Thanks, Khalid