From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [RFC PATCH v3 12/24] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Date: Fri, 31 Aug 2018 09:29:51 -0700 Message-ID: References: <20180830143904.3168-1-yu-cheng.yu@intel.com> <20180830143904.3168-13-yu-cheng.yu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180830143904.3168-13-yu-cheng.yu@intel.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Yu-cheng Yu , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra List-Id: linux-api@vger.kernel.org On 08/30/2018 07:38 AM, Yu-cheng Yu wrote: > + * Some processors can start a write, but ending up seeing > + * a read-only PTE by the time they get to the Dirty bit. > + * In this case, they will set the Dirty bit, leaving a > + * read-only, Dirty PTE which looks like a Shadow Stack PTE. > + * > + * However, this behavior has been improved and will not occur > + * on processors supporting Shadow Stacks. Without this > + * guarantee, a transition to a non-present PTE and flush the > + * TLB would be needed. Did we publicly document this behavior anywhere? I can't seem to find it.