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 <20201111162051.GG517454@elver.google.com>
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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Thu, 12 Nov 2020 01:24:02 +0100
Message-ID: <CAAeHK+x=8TF1Rda9mVCRe+-_A72BDSFg-e8w9mG-JKgCkfb8=g@mail.gmail.com>
Subject: Re: [PATCH v2 05/20] kasan: allow VMAP_STACK for HW_TAGS mode
To:     Marco Elver <elver@google.com>
Cc:     Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        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, Nov 11, 2020 at 5:20 PM Marco Elver <elver@google.com> wrote:
>
> On Tue, Nov 10, 2020 at 11:20PM +0100, Andrey Konovalov 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>
> > Link: https://linux-review.googlesource.com/id/I3552cbc12321dec82cd7372676e9372a2eb452ac
> > ---
>
> Shouldn't this be in the other series?

I don't think it makes much difference considering the series will go
in together.

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

Thanks!

>
> >  arch/Kconfig | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index 56b6ccc0e32d..7e7d14fae568 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -914,16 +914,16 @@ 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
> > --
> > 2.29.2.222.g5d2a92d10f8-goog
> >