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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, Yu-cheng Yu References: <20230227222957.24501-1-rick.p.edgecombe@intel.com> <20230227222957.24501-23-rick.p.edgecombe@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 924D91A001B X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: pu4y1py1m7i91koz1w7k14uhby4cdcjf X-HE-Tag: 1679073382-178348 X-HE-Meta: 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 ZrboaUjH pdvNVrIh6GJ1RTgI3XAnFfnJPzoIAtPE4PQMGXCdG+jH4vGDokiC96w4/TC3R1SYle5nOqHUYyk1Usuva3JUTHX4PJKT8XVJQE9i5MXxypB8D4p5IdCCF5JuhGc8kvgkyqUqdt/i23dQTYsKTutHaovmBNlN0bARipyFIsmlvXwGE1T2K2h7VTsFhFcYH6QgiYjZcwjHxdlHbHQ4y8L5ekLbmN69tcgxxI0csefkveATxkAY= 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 3/17/23 10:12, Deepak Gupta wrote: >> /* >> - * Stack area - automatically grows in one direction >> + * Stack area >> * >> - * VM_GROWSUP / VM_GROWSDOWN VMAs are always private anonymous: >> - * do_mmap() forbids all other combinations. >> + * VM_GROWSUP, VM_GROWSDOWN VMAs are always private >> + * anonymous. do_mmap() forbids all other combinations. >> */ >> static inline bool is_stack_mapping(vm_flags_t flags) >> { >> - return (flags & VM_STACK) == VM_STACK; >> + return ((flags & VM_STACK) == VM_STACK) || (flags & VM_SHADOW_STACK); > Same comment here. `VM_SHADOW_STACK` is an x86 specific way of > encoding a shadow stack. > Instead let's have a proxy here which allows architectures to have > their own encodings to represent a shadow stack. This doesn't _preclude_ another architecture from coming along and doing that, right? I'd just prefer that shadow stack architecture #2 comes along and refactors this in precisely the way _they_ need it.