Re: [PATCH mm v3 05/19] kasan: allow VMAP_STACK for HW_TAGS mode

From: Dmitry Vyukov <dvyukov@google.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Marco Elver <elver@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Alexander Potapenko <glider@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH mm v3 05/19] kasan: allow VMAP_STACK for HW_TAGS mode
Date: Mon, 16 Nov 2020 12:01:59 +0100	[thread overview]
Message-ID: <CACT4Y+Y+5g24oAMDL7SKESXO6p6tW=OrC9Y8S1=Lhs6DwAkuUA@mail.gmail.com> (raw)
In-Reply-To: <89bf275f233121fc0ad695693a072872d4deda5d.1605305978.git.andreyknvl@google.com>

On Fri, Nov 13, 2020 at 11:20 PM 'Andrey Konovalov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> Even though hardware tag-based mode currently doesn't support checking
> vmalloc allocations, it doesn't use shadow memory and works with
> VMAP_STACK as is. Change VMAP_STACK definition accordingly.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Reviewed-by: Marco Elver <elver@google.com>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Link: https://linux-review.googlesource.com/id/I3552cbc12321dec82cd7372676e9372a2eb452ac
> ---
>  arch/Kconfig | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 9ebdab3d0ca2..546869c3269d 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -921,16 +921,16 @@ config VMAP_STACK
>         default y
>         bool "Use a virtually-mapped stack"
>         depends on HAVE_ARCH_VMAP_STACK
> -       depends on !KASAN || KASAN_VMALLOC
> +       depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
>         help
>           Enable this if you want the use virtually-mapped kernel stacks
>           with guard pages.  This causes kernel stack overflows to be
>           caught immediately rather than causing difficult-to-diagnose
>           corruption.
>
> -         To use this with KASAN, the architecture must support backing
> -         virtual mappings with real shadow memory, and KASAN_VMALLOC must
> -         be enabled.
> +         To use this with software KASAN modes, the architecture must support
> +         backing virtual mappings with real shadow memory, and KASAN_VMALLOC
> +         must be enabled.
>
>  config ARCH_OPTIONAL_KERNEL_RWX
>         def_bool n
> --
> 2.29.2.299.gdc1121823c-goog
>
> --
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