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Date: Wed, 3 Jun 2015 09:44:28 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Alexander Popov <alpopov@ptsecurity.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrey Ryabinin <a.ryabinin@samsung.com>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Alexander Kuleshov <kuleshovmail@gmail.com>,
        Borislav Petkov <bp@suse.de>, Denys Vlasenko <dvlasenk@redhat.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/1] x86_64: fix KASan shadow region page tables
Message-ID: <20150603074427.GA1598@gmail.com>
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* Alexander Popov <alpopov@ptsecurity.com> wrote:

>  #ifdef CONFIG_KASAN
>  void __init kasan_map_early_shadow(pgd_t *pgd);
> +void __init kasan_early_init(void);
>  void __init kasan_init(void);
>  #else
>  static inline void kasan_map_early_shadow(pgd_t *pgd) { }
> +static inline void kasan_early_init(void) { }
>  static inline void kasan_init(void) { }
>  #endif
>  
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 2b55ee6..e9a84a1 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -161,11 +161,15 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
>  	/* Kill off the identity-map trampoline */
>  	reset_early_page_tables();
>  
> -	kasan_map_early_shadow(early_level4_pgt);
> -
> -	/* clear bss before set_intr_gate with early_idt_handler */
> +	/*
> +	 * Clear bss before kasan_early_init and set_intr_gate
> +	 * with early_idt_handler
> +	 */
>  	clear_bss();
>  
> +	kasan_early_init();
> +	kasan_map_early_shadow(early_level4_pgt);

So why isn't kasan_map_early_shadow() called in kasan_early_init()?

High level x86 init code should not be polluted with too many low level details.

Thanks,

	Ingo