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Date:   Wed, 16 Aug 2023 19:26:12 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Arnd Bergmann <arnd@arndb.de>, Oleg Nesterov <oleg@redhat.com>,
        Eric Biederman <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Shuah Khan <shuah@kernel.org>,
        "Rick P. Edgecombe" <rick.p.edgecombe@intel.com>,
        Deepak Gupta <debug@rivosinc.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
        "H.J. Lu" <hjl.tools@gmail.com>,
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        Palmer Dabbelt <palmer@dabbelt.com>,
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Subject: Re: [PATCH v4 07/36] arm64/gcs: Provide copy_to_user_gcs()
Message-ID: <60eeefc9-96db-4d4a-b0e4-751cba540471@sirena.org.uk>
References: <20230807-arm64-gcs-v4-0-68cfa37f9069@kernel.org>
 <20230807-arm64-gcs-v4-7-68cfa37f9069@kernel.org>
 <ZNZjdXTJw2p5vh7C@arm.com>
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On Fri, Aug 11, 2023 at 05:36:05PM +0100, Catalin Marinas wrote:
> On Mon, Aug 07, 2023 at 11:00:12PM +0100, Mark Brown wrote:
> > +static inline int copy_to_user_gcs(unsigned long __user *addr,
> > +				   unsigned long *val,
> > +				   int count)

> I think it makes more sense to have a put_user_gcs() of a single
> element. I've only seen it used with 2 elements in the signal code but
> we could as well do two put_user_gcs() calls (as we do for other stuff
> that we push to the signal frame).

Right, it's just the two element array in the signals code and the one
element for the context token in map_shadow_stack().  I can refactor to
a single read/write operation, I'd originally written it that way but I
wasn't thrilled with either writing a load of fun macros to mirror the
way vanilla put_user() is written or having code that looked very
different to the other similarly named functions were done.

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