linux-kernel - Re: [PATCH mm 2/2] Revert "kasan, arm64: don't allow SW_TAGS with ARM64

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Date:   Wed, 9 Dec 2020 19:51:05 +0100
From:   Marco Elver <elver@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH mm 2/2] Revert "kasan, arm64: don't allow SW_TAGS with ARM64_MTE"

On Wed, 9 Dec 2020 at 19:24, Andrey Konovalov <andreyknvl@...gle.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@...gle.com>

Reviewed-by: Marco Elver <elver@...gle.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
>