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Date: Tue, 27 Mar 2018 22:02:23 +0200
From: Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH v2 03/15] khwasan: add CONFIG_KASAN_CLASSIC and
 CONFIG_KASAN_TAGS
Message-ID: <20180327200223.5ku2eqkppi7z3sd2@gmail.com>
References: <cover.1521828273.git.andreyknvl@google.com>
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To: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>, Alexander Potapenko <glider@google.com>, Dmitry Vyukov <dvyukov@google.com>, Jonathan Corbet <corbet@lwn.net>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Christoffer Dall <christoffer.dall@linaro.org>, Marc Zyngier <marc.zyngier@arm.com>, Christopher Li <sparse@chrisli.org>, Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, Michal Marek <michal.lkml@markovi.net>, Mark Rutland <mark.rutland@arm.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Yury Norov <ynorov@caviumnetworks.com>, Nick Desaulniers <ndesaulniers@google.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Kristina Martsenko <kristina.martsenko@arm.com>, Punit Agrawal <punit.agrawal@arm.com>, Dave Martin <Dave.Martin@arm.com>, Michael Weiser <michael.weiser@gmx.de>, James Morse <james.morse@arm.com>, Julien Thierry <julien.thierry@arm.com>, Steve Capper <steve.capper@arm.com>, Tyler Baicar <tbaicar@codeaurora.org>, "Eric W . Biederman" <ebiederm@xmission.com>, Stephen Boyd <stephen.boyd@linaro.org>, Thomas Gleixner <tglx@linutronix.de>, Paul Lawrence <paullawrence@google.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, David Woodhouse <dwmw@amazon.co.uk>, Sandipan Das <sandipan@linux.vnet.ibm.com>, Kees Cook <keescook@chromium.org>, Herbert Xu <herbert@gondor.apana.org.au>, Geert Uytterhoeven <geert@linux-m68k.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Arnd Bergmann <arnd@arndb.de>, kasan-dev <kasan-dev@googlegroups.com>, linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, kvmarm@lists.cs.columbia.edu, linux-sparse@vger.kernel.org, Linux Memory Management List <linux-mm@kvack.org>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, Kostya Serebryany <kcc@google.com>, Evgeniy Stepanov <eugenis@google.com>, Lee Smith <Lee.Smith@arm.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Jacob Bramley <Jacob.Bramley@arm.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Kees Cook <keescook@google.com>, Jann Horn <jannh@google.com>, Mark Brand <markbrand@google.com>


* Andrey Konovalov <andreyknvl@google.com> wrote:

> On Sat, Mar 24, 2018 at 9:43 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> >> This commit splits the current CONFIG_KASAN config option into two:
> >> 1. CONFIG_KASAN_CLASSIC, that enables the classic KASAN version (the one
> >>    that exists now);
> >> 2. CONFIG_KASAN_TAGS, that enables KHWASAN.
> >
> > Sorry, but this is pretty obscure naming scheme that doesn't explain the primary
> > difference between these KASAN models to users: that the first one is a pure
> > software implementation and the other is hardware-assisted.
> >
> > Reminds me of the transparency of galactic buerocracy in "The Hitchhiker's Guide
> > to the Galaxy":
> >
> >   a??But look, you found the notice, didna??t you?a??
> >   a??Yes,a?? said Arthur, a??yes I did. It was on display in the bottom of a locked filing
> >    cabinet stuck in a disused lavatory with a sign on the door saying a??Beware of the
> >    Leopard.a??
> >
> > I'd suggest something more expressive, such as:
> >
> >         CONFIG_KASAN
> >           CONFIG_KASAN_GENERIC
> >           CONFIG_KASAN_HW_ASSIST
> >
> > or so?
> >
> > The 'generic' variant will basically run on any CPU. The 'hardware assisted' one
> > needs support from the CPU.
> >
> > The following ones might also work:
> >
> >    CONFIG_KASAN_HWASSIST
> >    CONFIG_KASAN_HW_TAGS
> >    CONFIG_KASAN_HWTAGS
> >
> > ... or simply CONFIG_KASAN_SW/CONFIG_KASAN_HW.
> >
> > If other types of KASAN hardware acceleration are implemented in the future then
> > the CONFIG_KASAN_HW namespace can be extended:
> >
> >         CONFIG_KASAN_HW_TAGS
> >         CONFIG_KASAN_HW_KEYS
> >         etc.
> 
> How about these two:
> 
> CONFIG_KASAN_GENERIC
> CONFIG_KASAN_HW
> 
> ?
> 
> Shorter config name looks better to me and I think it makes sense to
> name the new config just HW, as there's only one HW implementation
> right now. When (and if) there are more, we can expand the config name
> as you suggested (CONFIG_KASAN_HW_TAGS, CONFIG_KASAN_HW_KEYS, etc).

Sure, sounds good to me!

Thanks,

	Ingo