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(p200300cbc706740083daebadba7fc97c.dip0.t-ipconnect.de. [2003:cb:c706:7400:83da:ebad:ba7f:c97c]) by smtp.gmail.com with ESMTPSA id n4-20020a5d4204000000b0031c5dda3aedsm3811087wrq.95.2023.08.22.08.21.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Aug 2023 08:21:11 -0700 (PDT) Message-ID: <8f2cf5af-cad7-a69c-e8ec-39f48deae1cb@redhat.com> Date: Tue, 22 Aug 2023 17:21:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v5 11/37] mm: Define VM_SHADOW_STACK for arm64 when we support GCS Content-Language: en-US To: Mark Brown , Catalin Marinas , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy Cc: "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org References: <20230822-arm64-gcs-v5-0-9ef181dd6324@kernel.org> <20230822-arm64-gcs-v5-11-9ef181dd6324@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230822-arm64-gcs-v5-11-9ef181dd6324@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 22.08.23 15:56, Mark Brown wrote: > Use VM_HIGH_ARCH_5 for guarded control stack pages. > > Signed-off-by: Mark Brown > --- > Documentation/filesystems/proc.rst | 2 +- > fs/proc/task_mmu.c | 3 +++ > include/linux/mm.h | 12 +++++++++++- > 3 files changed, 15 insertions(+), 2 deletions(-) > > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst > index 6ccb57089a06..086a0408a4d7 100644 > --- a/Documentation/filesystems/proc.rst > +++ b/Documentation/filesystems/proc.rst > @@ -566,7 +566,7 @@ encoded manner. The codes are the following: > mt arm64 MTE allocation tags are enabled > um userfaultfd missing tracking > uw userfaultfd wr-protect tracking > - ss shadow stack page > + ss shadow/guarded control stack page > == ======================================= > > Note that there is no guarantee that every flag and associated mnemonic will > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index cfab855fe7e9..e8c50848bb16 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -711,6 +711,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) > #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ > #ifdef CONFIG_X86_USER_SHADOW_STACK > [ilog2(VM_SHADOW_STACK)] = "ss", > +#endif > +#ifdef CONFIG_ARM64_GCS > + [ilog2(VM_SHADOW_STACK)] = "ss", > #endif See my comment below. > }; > size_t i; > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 43fe625b85aa..3f939ae212e5 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -372,7 +372,17 @@ extern unsigned int kobjsize(const void *objp); > * having a PAGE_SIZE guard gap. > */ > # define VM_SHADOW_STACK VM_HIGH_ARCH_5 > -#else > +#endif > + > +#if defined(CONFIG_ARM64_GCS) > +/* > + * arm64's Guarded Control Stack implements similar functionality and > + * has similar constraints to shadow stacks. > + */ > +# define VM_SHADOW_STACK VM_HIGH_ARCH_5 > +#endif Shouldn't that all just merged with the previous define(s)? Also, I wonder if we now want to have CONFIG_HAVE_ARCH_SHADOW_STACK or similar. -- Cheers, David / dhildenb