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From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Fri, 23 Jun 2023 14:40:28 +0200
Message-ID: <CA+fCnZfrUY+EZ8w6zDhfjOr=JSFS6bHO7JjVHx0pEykNXZQecg@mail.gmail.com>
Subject: Re: [PATCH v2] kasan: fix mention for KASAN_HW_TAGS
To:     Chanho Min <chanho.min@lge.com>
Cc:     dvyukov@google.com, elver@google.com, glider@google.com,
        gunho.lee@lge.com, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        ryabinin.a.a@gmail.com, vincenzo.frascino@arm.com
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On Fri, Jun 23, 2023 at 9:58=E2=80=AFAM Chanho Min <chanho.min@lge.com> wro=
te:
>
> This patch fixes description of the KASAN_HW_TAGS's memory consumption.
> KASAN_HW_TAGS are dependent on the HW implementation and are not reserved
> from system memory like shadow memory.
>
> Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
> Signed-off-by: Chanho Min <chanho.min@lge.com>
> ---
>  lib/Kconfig.kasan | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index fdca89c05745..f8f9e12510b7 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -124,7 +124,8 @@ config KASAN_HW_TAGS
>           Supported only on arm64 CPUs starting from ARMv8.5 and relies o=
n
>           Memory Tagging Extension and Top Byte Ignore.
>
> -         Consumes about 1/32nd of available memory.
> +         Does not consume memory by itself but relies on the 1/32nd of
> +         available memory being reserved by the firmware when MTE is ena=
bled.
>
>           May potentially introduce problems related to pointer casting a=
nd
>           comparison, as it embeds a tag into the top byte of each pointe=
r.
> --
> 2.17.1
>

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>

Thank you!