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(p200300cbc7058300e5194218a8b55bec.dip0.t-ipconnect.de. [2003:cb:c705:8300:e519:4218:a8b5:5bec]) by smtp.gmail.com with ESMTPSA id z3-20020adff1c3000000b002c559def236sm76762wro.57.2023.02.20.04.58.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Feb 2023 04:58:40 -0800 (PST) Message-ID: <6ccc8d30-336a-12af-1179-5dc4eca3048d@redhat.com> Date: Mon, 20 Feb 2023 13:58:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH v6 22/41] mm/mmap: Add shadow stack pages to memory accounting Content-Language: en-US To: Rick Edgecombe , 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 , 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, debug@rivosinc.com Cc: Yu-cheng Yu References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-23-rick.p.edgecombe@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230218211433.26859-23-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 18.02.23 22:14, Rick Edgecombe wrote: > From: Yu-cheng Yu > > 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. > > Account shadow stack pages to stack memory. > > Reviewed-by: Kees Cook > Tested-by: Pengfei Xu > Tested-by: John Allen > Signed-off-by: Yu-cheng Yu > Co-developed-by: Rick Edgecombe > Signed-off-by: Rick Edgecombe > Cc: Kees Cook > > --- > v3: > - Remove unneeded VM_SHADOW_STACK check in accountable_mapping() > (Kirill) > > v2: > - Remove is_shadow_stack_mapping() and just change it to directly bitwise > and VM_SHADOW_STACK. > > Yu-cheng v26: > - Remove redundant #ifdef CONFIG_MMU. > > Yu-cheng v25: > - Remove #ifdef CONFIG_ARCH_HAS_SHADOW_STACK for is_shadow_stack_mapping(). > --- > mm/mmap.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 425a9349e610..9f85596cce31 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3290,6 +3290,8 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) > mm->exec_vm += npages; > else if (is_stack_mapping(flags)) > mm->stack_vm += npages; > + else if (flags & VM_SHADOW_STACK) > + mm->stack_vm += npages; Why not modify is_stack_mapping() ? -- Thanks, David / dhildenb