linux-kernel - Re: [PATCH] arm64: delete dead code in this_cpu_set

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Date:   Wed, 19 Apr 2023 16:29:42 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Dan Carpenter <dan.carpenter@...aro.org>
Cc:     James Morse <james.morse@....com>, Will Deacon <will@...nel.org>,
        Kristina Martsenko <kristina.martsenko@....com>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>,
        Liu Song <liusong@...ux.alibaba.com>,
        D Scott Phillips <scott@...amperecomputing.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] arm64: delete dead code in this_cpu_set_vectors()

On Wed, 19 Apr 2023 at 09:58, Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> The "slot" variable is an enum, and in this context it is an unsigned
> int.  So the type means it can never be negative and also we never pass
> invalid data to this function.  If something did pass invalid data then
> this check would be insufficient protection.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>

Acked-by: Ard Biesheuvel <ardb@...nel.org>

> ---
>  arch/arm64/kernel/proton-pack.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c
> index fca9cc6f5581..05f40c4e18fd 100644
> --- a/arch/arm64/kernel/proton-pack.c
> +++ b/arch/arm64/kernel/proton-pack.c
> @@ -966,9 +966,6 @@ static void this_cpu_set_vectors(enum arm64_bp_harden_el1_vectors slot)
>  {
>         const char *v = arm64_get_bp_hardening_vector(slot);
>
> -       if (slot < 0)
> -               return;
> -
>         __this_cpu_write(this_cpu_vector, v);
>
>         /*
> --
> 2.39.2
>