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Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , "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 Subject: Re: [PATCH v4 03/36] arm64/gcs: Document the ABI for Guarded Control Stacks Message-ID: References: <20230807-arm64-gcs-v4-0-68cfa37f9069@kernel.org> <20230807-arm64-gcs-v4-3-68cfa37f9069@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="LNILMu582aOVL6hM" Content-Disposition: inline In-Reply-To: X-Cookie: Your aim is high and to the right. X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 829BF40003 X-Stat-Signature: nz6toj1nds56t9emesfbkhpmym9hmsq9 X-HE-Tag: 1692387493-495165 X-HE-Meta: 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 fT2AQ7P6 oI4nTXlIPNxA0QJjs8xWxf0CU0rhX1oU/rUCeqw7c3l/4nSYem3tNR3JqGMEoWMvQMIxrwyYtrzc7OcFOG6uSzvI4N2k+knGrdQRdJeJLsbdVywhA8a881sgHAyZd9wBsubjhZK2UzQ3ijdm0+l+UVpR7uCvjNT7pwY29cVi4wn+VqQyvUp3hK/4R5LqgXVShcEw3BMidxBUmcqtzjq3F85vfWvNXHfL60RtyAbJm5fPx/USqRLEerJeGtvX0euv90OqKG5k3gWN3A0mNTcLEAoNBpciIrP6jb53ZZD7RgOxNRgYtfiGLxojtYhWr9m7fuGf9uloJpTSZhQvwCJ3QrN+cCdOujU3SA1s8OkT5HnIpqlbdy4haO4HnGup2P1mioq+TkEqSeQrnxdBCoCKj6cgndVq6CoCurIV11wJngsC/1DE= 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: --LNILMu582aOVL6hM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Aug 18, 2023 at 06:29:54PM +0100, Catalin Marinas wrote: > A related question - it may have been discussed intensively on the x86 > thread (I may read it sometime) - why not have the libc map the shadow Your assumption that this is a single thread feels optimistic there. > stack and pass the pointer/size to clone3()? It saves us from having to > guess what the right size we'd need. struct clone_args is extensible. I can't recall or locate the specific reasoning there right now, perhaps Rick or someone else can? I'd guess there would be compat concerns for things that don't go via libc which would complicate the story with identifying and marking things as GCS/SS safe, it's going to be more robust to just supply a GCS if the process is using it. That said having a default doesn't preclude us using the extensibility to allow userspace directly to control the GCS size, I would certainly be in favour of adding support for that. > (I plan to get back next week to this series, I'll need to read a bit > more on the spec) I've been making changes, mostly in response to your feedback, so there should be a new version on Monday even if not everything is addressed yet. --LNILMu582aOVL6hM Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmTfyJkACgkQJNaLcl1U h9Cw3Af8Cnyy0Sa1PU1lq3c1HV/d6eNcVzOoN4kECuID3B/GKxWng90W0Z7wR75z Wl9H0WZxlDkqd/voFGHAJTEtlcEZMg6xNByq8Rhq2jw6R2EX3O8P6+Uqumjb3UQ8 wb+PJyloj3BhXcQPiMH8vFHAs6b81DyPYo9NtaCLsYbtZv4MwGjgJKRrAl8+O2ct n/1P1Hpp/XUeTZUZvyWxrBdDUD7nLq9mQe2/+h6NxTtchrNTb98Kvgk7JrRefjrB 7kehDj9XiBJt5vVkoSO+e5aVln7wgwWor3KsjviaeNzyXglWrx+VBIc8OT6FMiJw VIA6Wrc8ikvi1fZ/oooK9TnU+p5chw== =RgY5 -----END PGP SIGNATURE----- --LNILMu582aOVL6hM--