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Date: Wed, 7 Nov 2018 18:10:54 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v10 08/22] kasan, arm64: untag address in __kimg_to_phys
 and _virt_addr_is_linear
Message-ID: <20181107181054.GC255021@arrakis.emea.arm.com>
References: <cover.1541525354.git.andreyknvl@google.com>
 <b2aa056b65b8f1a410379bf2f6ef439d5d99e8eb.1541525354.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>, Will Deacon <will.deacon@arm.com>, Christoph Lameter <cl@linux.com>, Andrew Morton <akpm@linux-foundation.org>, Mark Rutland <mark.rutland@arm.com>, Nick Desaulniers <ndesaulniers@google.com>, Marc Zyngier <marc.zyngier@arm.com>, Dave Martin <dave.martin@arm.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, "Eric W . Biederman" <ebiederm@xmission.com>, Ingo Molnar <mingo@kernel.org>, Paul Lawrence <paullawrence@google.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Arnd Bergmann <arnd@arndb.de>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Kate Stewart <kstewart@linuxfoundation.org>, Mike Rapoport <rppt@linux.vnet.ibm.com>, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, Vishwath Mohan <vishwath@google.com>, Chintan Pandya <cpandya@codeaurora.org>, Jacob Bramley <Jacob.Bramley@arm.com>, Jann Horn <jannh@google.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Lee Smith <Lee.Smith@arm.com>, Kostya Serebryany <kcc@google.com>, Mark Brand <markbrand@google.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Evgeniy Stepanov <eugenis@google.com>

On Tue, Nov 06, 2018 at 06:30:23PM +0100, Andrey Konovalov wrote:
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -92,6 +92,15 @@
>  #define KASAN_THREAD_SHIFT	0
>  #endif
>  
> +#ifdef CONFIG_KASAN_SW_TAGS
> +#define KASAN_TAG_SHIFTED(tag)		((unsigned long)(tag) << 56)
> +#define KASAN_SET_TAG(addr, tag)	(((addr) & ~KASAN_TAG_SHIFTED(0xff)) | \
> +						KASAN_TAG_SHIFTED(tag))
> +#define KASAN_RESET_TAG(addr)		KASAN_SET_TAG(addr, 0xff)
> +#else
> +#define KASAN_RESET_TAG(addr)		addr
> +#endif

I think we should reuse the untagged_addr() macro we have in uaccess.h
(make it more general and move to another header file).

-- 
Catalin