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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 , 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 , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com, Yu-cheng Yu , Christoph Hellwig Subject: Re: [PATCH v4 08/39] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Message-ID: References: <20221203003606.6838-1-rick.p.edgecombe@intel.com> <20221203003606.6838-9-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20221203003606.6838-9-rick.p.edgecombe@intel.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9C708160004 X-Stat-Signature: a9fap1dbr7rmk6e1hk6qcxmu43cfhdsq X-HE-Tag: 1671563527-459277 X-HE-Meta: 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 voBaNHSi NLRhfZaWKTWpj8ypQkZkqeA+U9oupp95n9weiKtwcDgzYfEV/fZ2KXsPrXwwZwukuMLGImayHXt0HUnxpx+0pcaJ8mguH3RKUCYlNse2yzH5nBUxY2kLFLYP9a92q9nIf9hWH 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: Just typos and spelling fixes: On Fri, Dec 02, 2022 at 04:35:35PM -0800, Rick Edgecombe wrote: > From: Yu-cheng Yu > > New processors that support Shadow Stack regard Write=0,Dirty=1 PTEs as > shadow stack pages. > > In normal cases, it can be helpful to create Write=1 PTEs as also Dirty=1 > if HW dirty tracking is not needed, because if the Dirty bit is not already > set the CPU has to set Dirty=1 when it the memory gets written to. This s/it // > creates addiontal work for the CPU. "additional" > So tradional wisdom was to simply set Unknown word [tradional] in commit message. Suggestions: ['traditional', ... > the Dirty bit whenever you didn't care about it. However, it was never > really very helpful for read only kernel memory. read-only > When CR4.CET=1 and IA32_S_CET.SH_STK_EN=1, some instructions can write to > such supervisor memory. The kernel does not set IA32_S_CET.SH_STK_EN, so > avoiding kernel Write=0,Dirty=1 memory is not strictly needed for any > functional reason. But having Write=0,Dirty=1 kernel memory doesn't have > any functional benefit either, so to reduce ambiguity between shadow stack > and regular Write=0 pages, removed Dirty=1 from any kernel Write=0 PTEs. s/removed/remove/ -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette