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Date:   Thu, 1 Oct 2020 19:59:19 +0200
From:   elver@google.com
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        kasan-dev@googlegroups.com,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Elena Petrova <lenaptr@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 33/39] kasan, x86, s390: update undef CONFIG_KASAN
Message-ID: <20201001175919.GT4162920@elver.google.com>
References: <cover.1600987622.git.andreyknvl@google.com>
 <78ebf3bed0458172fec9e1e32f2d29d7c8c37341.1600987622.git.andreyknvl@google.com>
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On Fri, Sep 25, 2020 at 12:50AM +0200, Andrey Konovalov wrote:
> With the intoduction of hardware tag-based KASAN some kernel checks of
> this kind:
> 
>   ifdef CONFIG_KASAN
> 
> will be updated to:
> 
>   if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> 
> x86 and s390 use a trick to #undef CONFIG_KASAN for some of the code
> that isn't linked with KASAN runtime and shouldn't have any KASAN
> annotations.
> 
> Also #undef CONFIG_KASAN_GENERIC with CONFIG_KASAN.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

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

> ---
> Change-Id: I2a622db0cb86a8feb60c30d8cb09190075be2a90
> ---
>  arch/s390/boot/string.c         | 1 +
>  arch/x86/boot/compressed/misc.h | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/arch/s390/boot/string.c b/arch/s390/boot/string.c
> index b11e8108773a..faccb33b462c 100644
> --- a/arch/s390/boot/string.c
> +++ b/arch/s390/boot/string.c
> @@ -3,6 +3,7 @@
>  #include <linux/kernel.h>
>  #include <linux/errno.h>
>  #undef CONFIG_KASAN
> +#undef CONFIG_KASAN_GENERIC
>  #include "../lib/string.c"
>  
>  int strncmp(const char *cs, const char *ct, size_t count)
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index 726e264410ff..2ac973983a8e 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -12,6 +12,7 @@
>  #undef CONFIG_PARAVIRT_XXL
>  #undef CONFIG_PARAVIRT_SPINLOCKS
>  #undef CONFIG_KASAN
> +#undef CONFIG_KASAN_GENERIC
>  
>  /* cpu_feature_enabled() cannot be used this early */
>  #define USE_EARLY_PGTABLE_L5
> -- 
> 2.28.0.681.g6f77f65b4e-goog
>