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Subject: Re: [PATCH 25/35] kasan: introduce CONFIG_KASAN_HW_TAGS
To:     Andrey Konovalov <andreyknvl@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        kasan-dev@googlegroups.com
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Elena Petrova <lenaptr@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <cover.1597425745.git.andreyknvl@google.com>
 <8a499341bbe4767a4ee1d3b8acb8bd83420ce3a5.1597425745.git.andreyknvl@google.com>
From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-ID: <b7884e93-008f-6b9f-32d8-6c03c7e14243@arm.com>
Date:   Thu, 27 Aug 2020 12:33:15 +0100
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Hi Andrey,

On 8/14/20 6:27 PM, Andrey Konovalov wrote:
> +config·KASAN_HW_TAGS
> +» bool·"Hardware·tag-based·mode"
> +» depends·on·HAVE_ARCH_KASAN_HW_TAGS
> +» depends·on·SLUB
> +» help
> +» ··Enables·hardware·tag-based·KASAN·mode.
> +
> +» ··This·mode·requires·both·Memory·Tagging·Extension·and·Top·Byte·Ignore
> +» ··support·by·the·CPU·and·therefore·is·only·supported·for·modern·arm64
> +» ··CPUs·(MTE·added·in·ARMv8.5·ISA).
> +

I do not thing we should make KASAN_HW_TAGS MTE specific especially because it
is in the common code (e.g. SPARC ADI might want to implement it in future).

Probably would be better to provide some indirection in the generic code an
implement the MTE backend entirely in arch code.

Thoughts?

-- 
Regards,
Vincenzo