linux-kernel - Re: [PATCH v5 1/2] x86_64: remove not needed clear_page for init_level4

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Message-id: <55800C42.4050702@samsung.com>
Date:	Tue, 16 Jun 2015 14:45:06 +0300
From:	Andrey Ryabinin <a.ryabinin@...sung.com>
To:	Borislav Petkov <bp@...en8.de>,
	Alexander Popov <alpopov@...ecurity.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Alexander Kuleshov <kuleshovmail@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Kees Cook <keescook@...omium.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] x86_64: remove not needed clear_page for
 init_level4_page

On 06/16/2015 02:34 PM, Borislav Petkov wrote:
> On Tue, Jun 16, 2015 at 01:16:32PM +0200, Borislav Petkov wrote:
>> Now my hunch is that those entries get overwritten later but I wouldn't
>> want to debug any strange bugs from leftovers in init_level4_pgt so
>> having the clear_page() is actually a good thing.
> 
> So I guess we can do that:
> 
> #ifndef CONFIG_KASAN
>         clear_page(init_level4_pgt);
> #endif
> 

Ugh..

Can't we just move clear_page(init_level4_pgt) higher? Before or right after clear_bss() (iow before kasan_early_init()).



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