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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Thu, 14 Jan 2021 19:01:40 +0100
Message-ID: <CAAeHK+zD17_esgDvsUd3Yku4cCKDdADo82_u3c47tMWtHL63oQ@mail.gmail.com>
Subject: Re: [PATCH v2 11/14] kasan: fix bug detection via ksize for HW_TAGS mode
To:     Marco Elver <elver@google.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Will Deacon <will.deacon@arm.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Peter Collingbourne <pcc@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, Jan 13, 2021 at 5:54 PM Marco Elver <elver@google.com> wrote:
>
> > +/*
> > + * Unlike kasan_check_read/write(), kasan_check_byte() is performed even for
> > + * the hardware tag-based mode that doesn't rely on compiler instrumentation.
> > + */
> > +bool __kasan_check_byte(const void *addr, unsigned long ip);
> > +static __always_inline bool kasan_check_byte(const void *addr, unsigned long ip)
> > +{
> > +       if (kasan_enabled())
> > +               return __kasan_check_byte(addr, ip);
> > +       return true;
> > +}
>
> Why was this not added to kasan-checks.h? I'd assume including all of
> kasan.h is also undesirable for tag-based modes if we just want to do
> a kasan_check_byte().

It requires kasan_enabled() definition. I can move both to
kasan-checks.h if you prefer. However, the only place where
kasan_check_byte() is currently used includes kasan.h anyway.