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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aanTBA7Q5SU1zTtPDaMhX4nwG1EogaRTB6711DBMiXTmU8FRFzAcB7zQYgcUM2OaJ XHksqp0nMGR665Zm+lDgT+yDropmULnL8lKiWtjJKJ3NL1ecrCmrLU8OR7ZcsowhNV u+zivFcDWQqEkxqOD8K6xYSAKOOwaNrLKqXv3SiHTMwf1JJvLKTjXxiKAVOfTIyX6A QW2bcztZSCAVxYQoLX8XBJuGKkKkAorTgEuxggq4WcuU6lezBNTj3BInSRIVEXBTih tlOZte74whZIn/QZQ00VCk0r89EM0A76cAGvXtNTTd6uAX30BQpy9H3OHFzXJG137X 8lNOIn1prx5Vg== Date: Thu, 22 Feb 2024 13:57:53 +0000 From: Mark Brown To: "Edgecombe, Rick P" Cc: "dalias@libc.org" , "linux-arch@vger.kernel.org" , "suzuki.poulose@arm.com" , "Szabolcs.Nagy@arm.com" , "musl@lists.openwall.com" , "linux-fsdevel@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "kvmarm@lists.linux.dev" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "catalin.marinas@arm.com" , "oliver.upton@linux.dev" , "palmer@dabbelt.com" , "debug@rivosinc.com" , "aou@eecs.berkeley.edu" , "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" , "will@kernel.org" , "brauner@kernel.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" , "thiago.bauermann@linaro.org" , "akpm@linux-foundation.org" , "sorear@fastmail.com" , "linux-doc@vger.kernel.org" Subject: Re: [musl] Re: [PATCH v8 00/38] arm64/gcs: Provide support for GCS in userspace Message-ID: References: <20240221012736.GQ4163@brightrain.aerifal.cx> <20240221145800.GR4163@brightrain.aerifal.cx> <4a3809e8-61b2-4341-a868-292ba6e64e8a@sirena.org.uk> <20240221175717.GS4163@brightrain.aerifal.cx> <20240221183055.GT4163@brightrain.aerifal.cx> <20240221190639.GU4163@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: multipart/signed; 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X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 4DE4114000A X-Stat-Signature: 8rpotnjkqoxhd56a49c1y58qywrq9pxn X-Rspam-User: X-HE-Tag: 1708610287-585056 X-HE-Meta: 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 znCaSAdx AnfhPQzUBoD8mSa74PC+pgnGVnvxhEUROMOFJJq1fX3LeU3xwfRMKE4ihL4XpFdAvyDXMdDSiCuuzChPh7t5u8MFM15HqvmcQ7yeBgd+L0DMCyP3zCDxILCT+i5dsH2X8tutfnS/nzB8H4XN3r1MBusIdVxLGAMECwH4+y3fc2G94J7VD7dD+kW/WahHULD7F5mKzpPa4geENfGC2CuvwcvkPrPbjgS3+SU/1Yfvbfdfix/r7s51tHThcz5I5gYPqBCxk5NsQkw89lQsCBtqd344CEAu2Ogv2B/MKaJGd0iFLRAHVksr5vSR10iz7yvE5CsBPNaT3G885HwM8imcPnKXWI6Ai/I9C8fMktVy8ATnpvlbuMqEGX1r1my9NLrXxG+M/v60XPwXUujpyIGLZIoCUen4UVuA+qL4T+mivuRFakwo= 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: --Y7x2ZPCVf8cy8GEb Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Feb 21, 2024 at 07:22:21PM +0000, Edgecombe, Rick P wrote: > On Wed, 2024-02-21 at 14:06 -0500, dalias@libc.org wrote: > > It's fine to turn RDSSP into an actual emulated read of the SSP, or > > at > > least an emulated load of zero so that uninitialized data is not left > > in the target register. > We can't intercept RDSSP, but it becomes a NOP by default. (disclaimer > x86-only knowledge). For arm64 we have a separate control GCSCRE0_EL1.nTR for access to GCSPR_EL0 (our SSP equivalent) we can use. > > I have not looked at all the instructions that become #UD but I > > suspect they all have reasonable trivial ways to implement a > > "disabled" version of them that userspace can act upon reasonably. > This would have to be thought through functionally and performance > wise. I'm not opposed if can come up with a fully fleshed out plan. How > serious are you in pursuing musl support, if we had something like > this? Same here, we have to be careful since it's defining ABI in a way that we don't normally provide ABI but if there's a clear case for doing it then... --Y7x2ZPCVf8cy8GEb Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmXXUuAACgkQJNaLcl1U h9CWhgf9ENKHpmQFWkFp9BvnSQpoqzt8GvTsea21+X/Sj2LF1t9awlhI1ZonFcLg kiWOH7voRFXaX11HTooF+5zW0lljzQzeKy6a4cAqvyhV93pQz5U7Tzuk5xqkLe3o mtXBUEWVIO/JPNSAwHNb44hXL7AjS1MEYgj0iqYvqWCYqikKit3kjOjJrc3jdb4y 3NQgra/qAykoQji1F3ZFkEtRyHALvMWET9TzzVyrCoTYPzIRzCWnkkBxKsNMokGC nwxW+cuoESrLNygNc/V3CbbUqAYkdO7AbmSvBvzQ0pboXO5M+p4sPnapddZeoYiK JVmWfU7+hu6JUz1Bj5tBIoRL24Q7Og== =mhhY -----END PGP SIGNATURE----- --Y7x2ZPCVf8cy8GEb--