Re: [PATCH v2 1/5] kasan, x86: move KASAN_SHADOW_OFFSET to the arch Kconfig

From: Andrey Ryabinin <a.ryabinin@samsung.com>
To: Paul Bolle <pebolle@tiscali.nl>
Cc: linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
	Alexander Potapenko <glider@google.com>,
	David Keitel <dkeitel@codeaurora.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"maintainer:X86 ARCHITECTURE..." <x86@kernel.org>
Subject: Re: [PATCH v2 1/5] kasan, x86: move KASAN_SHADOW_OFFSET to the arch Kconfig
Date: Mon, 18 May 2015 10:43:29 +0300	[thread overview]
Message-ID: <55599821.40409@samsung.com> (raw)
In-Reply-To: <1431775656.2341.10.camel@x220>

On 05/16/2015 02:27 PM, Paul Bolle wrote:
> On Fri, 2015-05-15 at 16:59 +0300, Andrey Ryabinin wrote:
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
> 
>> +config KASAN_SHADOW_OFFSET
>> +	hex
>> +	default 0xdffffc0000000000
> 
> This sets CONFIG_KASAN_SHADOW_OFFSET for _all_ X86 configurations,
> doesn't it?
> 

Right.

>> --- a/lib/Kconfig.kasan
>> +++ b/lib/Kconfig.kasan
>  
>> -config KASAN_SHADOW_OFFSET
>> -	hex
>> -	default 0xdffffc0000000000 if X86_64
> 
> While here it used to depend, at least, on HAVE_ARCH_KASAN. But grepping
> the tree shows the two places where CONFIG_KASAN_SHADOW_OFFSET is
> currently used are guarded by #ifdef CONFIG_KASAN. So perhaps the
> default line should actually read
> 	default 0xdffffc0000000000 if KASAN
> 
> after the move. Would that work?
> 

Yes, but I would rather add "depends on KASAN".

> 
> Paul Bolle
> 
> 