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Shutemov" To: Yu-cheng Yu Cc: 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 , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Subject: Re: [PATCH v23 11/28] x86/mm: Update pte_modify for _PAGE_COW Message-ID: <20210322113120.4qloiyj4ojmiis6n@box> References: <20210316151054.5405-1-yu-cheng.yu@intel.com> <20210316151054.5405-12-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210316151054.5405-12-yu-cheng.yu@intel.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: CCFA2D6 X-Stat-Signature: cc8343bo368guf5nr91bci5sx5k1d8au Received-SPF: none (shutemov.name>: No applicable sender policy available) receiver=imf12; identity=mailfrom; envelope-from=""; helo=mail-lf1-f51.google.com; client-ip=209.85.167.51 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616412674-65384 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: On Tue, Mar 16, 2021 at 08:10:37AM -0700, Yu-cheng Yu wrote: > The read-only and Dirty PTE has been used to indicate copy-on-write pages. > However, newer x86 processors also regard a read-only and Dirty PTE as a > shadow stack page. In order to separate the two, the software-defined > _PAGE_COW is created to replace _PAGE_DIRTY for the copy-on-write case, and > pte_*() are updated. > > Pte_modify() changes a PTE to 'newprot', but it doesn't use the pte_*(). > Introduce fixup_dirty_pte(), which sets a dirty PTE, based on _PAGE_RW, > to either _PAGE_DIRTY or _PAGE_COW. > > Apply the same changes to pmd_modify(). > > Signed-off-by: Yu-cheng Yu Reviewed-by: Kirill A. Shutemov -- Kirill A. Shutemov