Re: [PATCH v4 1/1] x86_64: fix KASan shadow region page tables

[Ingo Molnar <mingo@kernel.org>]

* 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