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b=nLSW8zDANEVNHFOtFyXlOB9m7Pc9xIeqUMFJpaJNXgyoNhBzVXEUk9opATfsy2oal wRbvuaumSqLUIa+NMSBfO/LMqX+4nSqtiio6HenhDMeGFWGnlOGELna0yPd2Irl9jO 5+MI5ynunAofTV7goPnqKF6+f5L1czOZ3ExA4GV3magiQkQIzKd9jyffRnP+4b5kBK L2N4V+xJ0pzQoB6JF+Kvtcj0gx7onTfczeFs6gwWM5KCfQlYS1P8nC+RSzSIx8HneL n7gwwtiX2MyG0bZYK6tkUUbfvV2ZJ+bZjgfm0jVXpQDKqS+WyK+6MqdutTajzX6ecw /B7NAIrU16Nng== Date: Wed, 13 Dec 2023 13:49:29 +0000 From: Mark Brown To: "Edgecombe, Rick P" Cc: "linux-arch@vger.kernel.org" , "suzuki.poulose@arm.com" , "Szabolcs.Nagy@arm.com" , "linux-fsdevel@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "catalin.marinas@arm.com" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "kvmarm@lists.linux.dev" , "oliver.upton@linux.dev" , "palmer@dabbelt.com" , "debug@rivosinc.com" , "aou@eecs.berkeley.edu" , "rppt@kernel.org" , "shuah@kernel.org" , "arnd@arndb.de" , "maz@kernel.org" , "oleg@redhat.com" , "fweimer@redhat.com" , "keescook@chromium.org" , "james.morse@arm.com" , "ebiederm@xmission.com" , "brauner@kernel.org" , "will@kernel.org" , "thiago.bauermann@linaro.org" , "hjl.tools@gmail.com" , "linux-kselftest@vger.kernel.org" , "paul.walmsley@sifive.com" , "ardb@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "linux-doc@vger.kernel.org" Subject: Re: [PATCH v7 02/39] prctl: arch-agnostic prctl for shadow stack Message-ID: References: <20231122-arm64-gcs-v7-0-201c483bd775@kernel.org> <20231122-arm64-gcs-v7-2-201c483bd775@kernel.org> <28c584ff-ef25-464f-852c-c5ddf66e5906@sirena.org.uk> <4acb51ebb3764f6a48a741d7b7d33f9a68c996fb.camel@intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="+/nsIWnogzOjsOHn" Content-Disposition: inline In-Reply-To: <4acb51ebb3764f6a48a741d7b7d33f9a68c996fb.camel@intel.com> X-Cookie: One size fits all. X-Rspamd-Queue-Id: 79E5540009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 48oq1qiunpj9eoujwby67ih5ujeizdyi X-HE-Tag: 1702475380-522600 X-HE-Meta: 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 um6qfOZD 1lAtC7AwsrjHtDrwGCGjN9sotFguK94Cm4/JLT3+zEh8/pRpegzAonfflHlhOAZ0q1fXHuUvGNHgCDR9tirDaA7T4ThQzBKMzoJDBVg07nSfpwnloCk5dO4C3+JNWJCT2YxAgHYl4eJRBBSbEcDfmxx4v1G/DQoHO2Qhp9TXpzofzvMZgaCwrQ42qi1Jp0Q569xmsFNigAF7XAWgF5VuUfirZHH9HfeFlJuNYsHsBHaJDswWuI+4MXaBVlNsS1yzua862mj9UcDOl7Tvbu34hfPOxr+oKSVHn3RZVHglaiysXuTi6UxNa2sae2QFrNU4vTvcdvlnD5lXlZELHVQEYom2ASxexq36D+vwGjmbG6TM53iM= 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: List-Subscribe: List-Unsubscribe: --+/nsIWnogzOjsOHn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Dec 12, 2023 at 09:22:59PM +0000, Edgecombe, Rick P wrote: > On Tue, 2023-12-12 at 20:26 +0000, Mark Brown wrote: > > In general if things have a need to get at prctl()s via ptrace we > > should > > just fix that, at least for arm64 there's things like the vector > > lengths > > that are currently controlled via prctl(), but it shouldn't be a > > blocker > > for the locking specifically. > ptrace arch_prctl() is a bit odd. Not all values of 'option' are > supported because ptrace arch_prctl's have to operate cross task. Some > have extra code to support doing this, and some only know how to > operate on the current task, so return an error in the ptrace case. It feels like x86 is doing some things via arch_prctl() rather than implementing specific ptrace() interfaces for them, there's a lot of stuff where ptrace isn't a great fit for due to it's concept that it's going to work with an array of registers so that's understandable. > I guess a benefit would be that there could be some arch agnostic > ptrace userspace code. And I'd also guess (really a guess) that most > ptracing code has some arch awareness already, but the other way is > probably non-zero. Same for shadow stack enabling code. Then on the > kernel side we'd have to add and support a ptrace prctl() solution. > Is it worth the effort? I don't have a strong opinion. I don't have a strong enough opinion on it to start working on it immediately at any rate. --+/nsIWnogzOjsOHn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmV5tmgACgkQJNaLcl1U h9CAhAf8CQEZOdWDIY7Wox4T7BzkaUfw/3Fa/4lTqu0TQ31mrybSqq9IHseTshgc Mn6pJLAuHfPGj1iDEGxc3ukqVD/LgxFzMPoA18ZkdIrRLEAxoeKcq1vvJLfl6zws GnWoqPcVdY1adnKNGo57jhoeE9pO71+2lfqK4yndK/BjR+iSo/PWM91Ub9SN2EbF /czeqjpXV+eRF11RAEHmYsx/Uwz3ibAIE9vc0Yn8X9x+EEJhRZ1op3afAqK/Jn5I X3sM+uRaDnWAb3KJ0C460J8jgjFuukww2GPdAFCp9HOQSXRYxKp4BfkxcAcAS9mL xBHVT6Pa6B/vaeTYas4nGzUoUcaukA== =4csw -----END PGP SIGNATURE----- --+/nsIWnogzOjsOHn--