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From:   Marco Elver <elver@google.com>
Date:   Wed, 9 Dec 2020 19:51:05 +0100
Message-ID: <CANpmjNM9suHQY-uQN9g5h=Vdv2wotDKNdcnHM=-RTtEb2sCZTA@mail.gmail.com>
Subject: Re: [PATCH mm 2/2] Revert "kasan, arm64: don't allow SW_TAGS with ARM64_MTE"
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, 9 Dec 2020 at 19:24, Andrey Konovalov <andreyknvl@google.com> wrote:
>
> This reverts "kasan, arm64: don't allow SW_TAGS with ARM64_MTE".
>
> In earlier versions on the hardware tag-based KASAN patchset in-kernel
> MTE used to be always enabled when CONFIG_ARM64_MTE is on. This caused
> conflicts with the software tag-based KASAN mode.
>
> This is no logner the case: in-kernel MTE is never enabled unless the
> CONFIG_KASAN_HW_TAGS is enabled, so there are no more conflicts with
> CONFIG_KASAN_SW_TAGS.
>
> Allow CONFIG_KASAN_SW_TAGS to be enabled even when CONFIG_ARM64_MTE is
> enabled.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  arch/arm64/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 6fefab9041d8..62a7668976a2 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -135,7 +135,7 @@ config ARM64
>         select HAVE_ARCH_JUMP_LABEL
>         select HAVE_ARCH_JUMP_LABEL_RELATIVE
>         select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
> -       select HAVE_ARCH_KASAN_SW_TAGS if (HAVE_ARCH_KASAN && !ARM64_MTE)
> +       select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN
>         select HAVE_ARCH_KASAN_HW_TAGS if (HAVE_ARCH_KASAN && ARM64_MTE)
>         select HAVE_ARCH_KFENCE
>         select HAVE_ARCH_KGDB
> --
> 2.29.2.576.ga3fc446d84-goog
>