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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id r6-20020a170902be0600b00199537a7466sm6345581pls.39.2023.02.19.12.39.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Feb 2023 12:39:29 -0800 (PST) Message-ID: <63f28901.170a0220.7090.af7b@mx.google.com> X-Google-Original-Message-ID: <202302191238.@keescook> Date: Sun, 19 Feb 2023 12:39:28 -0800 From: Kees Cook To: Rick Edgecombe 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 , 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, david@redhat.com, debug@rivosinc.com, linux-s390@vger.kernel.org Subject: Re: [PATCH v6 12/41] s390/mm: Introduce pmd_mkwrite_kernel() References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-13-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230218211433.26859-13-rick.p.edgecombe@intel.com> X-Rspam-User: X-Rspamd-Queue-Id: 09025180009 X-Rspamd-Server: rspam01 X-Stat-Signature: 9te86w3qysphwh9oubqbmqqwnsbfeh5b X-HE-Tag: 1676839170-340534 X-HE-Meta: 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 1BiRqLXG 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 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 Sat, Feb 18, 2023 at 01:14:04PM -0800, Rick Edgecombe wrote: > The x86 Control-flow Enforcement Technology (CET) feature includes a new > type of memory called shadow stack. This shadow stack memory has some > unusual properties, which requires some core mm changes to function > properly. > > One of these changes is to allow for pmd_mkwrite() to create different > types of writable memory (the existing conventionally writable type and > also the new shadow stack type). Future patches will convert pmd_mkwrite() > to take a VMA in order to facilitate this, however there are places in the > kernel where pmd_mkwrite() is called outside of the context of a VMA. > These are for kernel memory. So create a new variant called > pmd_mkwrite_kernel() and switch the kernel users over to it. Have > pmd_mkwrite() and pmd_mkwrite_kernel() be the same for now. Future patches > will introduce changes to make pmd_mkwrite() take a VMA. > > Only do this for architectures that need it because they call pmd_mkwrite() > in arch code without an associated VMA. Since it will only currently be > used in arch code, so do not include it in arch_pgtable_helpers.rst. > > Cc: linux-kernel@vger.kernel.org > Cc: linux-s390@vger.kernel.org > Cc: linux-arch@vger.kernel.org > Cc: linux-mm@kvack.org > Tested-by: Pengfei Xu > Suggested-by: David Hildenbrand > Signed-off-by: Rick Edgecombe Yup, 1:1 refactor. Reviewed-by: Kees Cook -- Kees Cook