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From:   Florian Weimer <fweimer@redhat.com>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     linux-kernel@vger.kernel.org, patches@lists.linux.dev,
        tglx@linutronix.de, linux-crypto@vger.kernel.org, x86@kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
        Carlos O'Donell <carlos@redhat.com>
Subject: Re: [PATCH v6 1/3] random: add vgetrandom_alloc() syscall
References: <20221121152909.3414096-1-Jason@zx2c4.com>
        <20221121152909.3414096-2-Jason@zx2c4.com>
Date:   Wed, 23 Nov 2022 11:46:58 +0100
In-Reply-To: <20221121152909.3414096-2-Jason@zx2c4.com> (Jason A. Donenfeld's
        message of "Mon, 21 Nov 2022 16:29:07 +0100")
Message-ID: <87v8n6lzh9.fsf@oldenburg.str.redhat.com>
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* Jason A. Donenfeld:

> + * The vgetrandom() function in userspace requires an opaque state, which this
> + * function provides to userspace, by mapping a certain number of special pages
> + * into the calling process. It takes a hint as to the number of opaque states
> + * desired, and returns the number of opaque states actually allocated, the
> + * size of each one in bytes, and the address of the first state.
> + */
> +SYSCALL_DEFINE3(vgetrandom_alloc, unsigned long __user *, num,
> +		unsigned long __user *, size_per_each, unsigned int, flags)

I think you should make this __u64, so that you get a consistent
userspace interface on all architectures, without the need for compat
system calls.

Thanks,
Florian