From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [PATCH 6/9] x86/mm: Introduce ptep_set_wrprotect_flush and related functions Date: Thu, 7 Jun 2018 18:20:36 -0700 Message-ID: References: <20180607143705.3531-1-yu-cheng.yu@intel.com> <20180607143705.3531-7-yu-cheng.yu@intel.com> <5c39caf1-2198-3c2b-b590-8c38a525747f@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Andy Lutomirski Cc: Yu-cheng Yu , LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H. J. Lu" , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com List-Id: linux-arch.vger.kernel.org On 06/07/2018 05:59 PM, Andy Lutomirski wrote: > Can you ask the architecture folks to clarify the situation? And, if > your notes are indeed correct, don't we need code to handle spurious > faults? I'll double check that I didn't misunderstand the situation and that it has not changed on processors with shadow stacks. But, as far as spurious faults, wouldn't it just be a fault because we've transiently gone to Present=0? We already do that when clearing the Dirty bit, so I'm not sure that's new. We surely already handle that one. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga04.intel.com ([192.55.52.120]:25751 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752139AbeFHBUi (ORCPT ); Thu, 7 Jun 2018 21:20:38 -0400 Subject: Re: [PATCH 6/9] x86/mm: Introduce ptep_set_wrprotect_flush and related functions References: <20180607143705.3531-1-yu-cheng.yu@intel.com> <20180607143705.3531-7-yu-cheng.yu@intel.com> <5c39caf1-2198-3c2b-b590-8c38a525747f@linux.intel.com> From: Dave Hansen Message-ID: Date: Thu, 7 Jun 2018 18:20:36 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andy Lutomirski Cc: Yu-cheng Yu , LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H. J. Lu" , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com Message-ID: <20180608012036.gGsDhDinB3rtReAZevaIEWVHflK1aeIyGm9ycil4ALY@z> On 06/07/2018 05:59 PM, Andy Lutomirski wrote: > Can you ask the architecture folks to clarify the situation? And, if > your notes are indeed correct, don't we need code to handle spurious > faults? I'll double check that I didn't misunderstand the situation and that it has not changed on processors with shadow stacks. But, as far as spurious faults, wouldn't it just be a fault because we've transiently gone to Present=0? We already do that when clearing the Dirty bit, so I'm not sure that's new. We surely already handle that one.