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 14:06:43 -0700 Message-ID: <56DDED63.8010302@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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56DDBE68.6080709@linux.intel.com> Sender: owner-linux-mm@kvack.org To: Dave Hansen , Andy Lutomirski , Rob Gardner Cc: David Miller , Jonathan Corbet , Andrew Morton , dingel@linux.vnet.ibm.com, zhenzhang.zhang@huawei.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" , bs List-Id: linux-arch.vger.kernel.org On 03/07/2016 10:46 AM, Dave Hansen wrote: > On 03/07/2016 08:06 AM, Khalid Aziz wrote: >> Top 4-bits of sparc64 virtual address are used for version tag only when >> a process has its PSTATE.mcde bit set and it is accessing a memory >> region that has ADI enabled on it (TTE.mcd set) and a version tag was >> set on the virtual address being accessed. These 4-bits retain their >> original semantics in all other cases. > > OK, so this effectively reduces the address space of a process using the > feature. Do we need to do anything explicit to keep an app from using > that address space? Do we make sure the kernel doesn't place VMAs > there? Do we respect mmap() hints that try to place memory there? > Good questions. Isn't set of valid VAs already constrained by VA_BITS (set to 44 in arch/sparc/include/asm/processor_64.h)? As I see it we are already not using the top 4 bits. Please correct me if I am wrong. 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 aserp1040.oracle.com ([141.146.126.69]:39710 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752850AbcCGVHa (ORCPT ); Mon, 7 Mar 2016 16:07:30 -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> From: Khalid Aziz Message-ID: <56DDED63.8010302@oracle.com> Date: Mon, 7 Mar 2016 14:06:43 -0700 MIME-Version: 1.0 In-Reply-To: <56DDBE68.6080709@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 , Rob Gardner Cc: David Miller , Jonathan Corbet , Andrew Morton , dingel@linux.vnet.ibm.com, zhenzhang.zhang@huawei.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: <20160307210643.m7FUgMvll_5ljXDSYagrQ5I5gquq429C8pECjIYQl5s@z> On 03/07/2016 10:46 AM, Dave Hansen wrote: > On 03/07/2016 08:06 AM, Khalid Aziz wrote: >> Top 4-bits of sparc64 virtual address are used for version tag only when >> a process has its PSTATE.mcde bit set and it is accessing a memory >> region that has ADI enabled on it (TTE.mcd set) and a version tag was >> set on the virtual address being accessed. These 4-bits retain their >> original semantics in all other cases. > > OK, so this effectively reduces the address space of a process using the > feature. Do we need to do anything explicit to keep an app from using > that address space? Do we make sure the kernel doesn't place VMAs > there? Do we respect mmap() hints that try to place memory there? > Good questions. Isn't set of valid VAs already constrained by VA_BITS (set to 44 in arch/sparc/include/asm/processor_64.h)? As I see it we are already not using the top 4 bits. Please correct me if I am wrong. Thanks, Khalid