Re: [PATCH v3 20/21] target/arm: Enable MTE for user-only

[Peter Maydell <peter.maydell@linaro.org>]

On Fri, 15 Jan 2021 at 22:47, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/cpu.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index abc0affd00..5e613a747a 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -208,6 +208,22 @@ static void arm_cpu_reset(DeviceState *dev)
>           * Do not modify this without other changes.
>           */
>          env->cp15.tcr_el[1].raw_tcr = (3ULL << 37);
> +
> +        /* Enable MTE */
> +        if (cpu_isar_feature(aa64_mte, cpu)) {
> +            /* Enable tag access, but leave TCF0 as No Effect (0). */
> +            env->cp15.sctlr_el[1] |= SCTLR_ATA0;
> +            /*
> +             * Exclude all tags, so that tag 0 is always used.
> +             * This corresponds to Linux current->thread.gcr_incl = 0.
> +             *
> +             * Set RRND, so that helper_irg() will generate a seed later.
> +             * Here in cpu_reset(), the crypto subsystem has not yet been
> +             * initialized.
> +             */
> +            env->cp15.gcr_el1 = 0x1ffff;
> +        }
> +
>  # ifdef TARGET_TAGGED_ADDRESSES
>          env->untagged_addr_mask = -1;
>  # endif
> --

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM