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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 , 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 , 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 Subject: Re: [PATCH v6 20/41] x86/mm: Teach pte_mkwrite() about stack memory Message-ID: <20230301154258.GC3505369@debug.ba.rivosinc.com> References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-21-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20230218211433.26859-21-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Sat, Feb 18, 2023 at 01:14:12PM -0800, Rick Edgecombe wrote: >If a VMA has the VM_SHADOW_STACK flag, it is shadow stack memory. So >when it is made writable with pte_mkwrite(), it should create shadow >stack memory, not conventionally writable memory. Now that pte_mkwrite() >takes a VMA, and places where shadow stack memory might be created pass >one, pte_mkwrite() can know when it should do this. > >So make pte_mkwrite() create shadow stack memory when the VMA has the >VM_SHADOW_STACK flag. Do the same thing for pmd_mkwrite(). > >This requires referencing VM_SHADOW_STACK in these functions, which are >currently defined in pgtable.h, however mm.h (where VM_SHADOW_STACK is >located) can't be pulled in without causing problems for files that >reference pgtable.h. So also move pte/pmd_mkwrite() into pgtable.c, where >they can safely reference VM_SHADOW_STACK. > >Tested-by: Pengfei Xu >Signed-off-by: Rick Edgecombe > Acked-by: Deepak Gupta