Re: [PATCH v8 02/28] x86/boot: Relocate definition of the initial state of CR0

[Borislav Petkov]

On Fri, Aug 18, 2017 at 05:27:43PM -0700, Ricardo Neri wrote:
> Both head_32.S and head_64.S utilize the same value to initialize the
> control register CR0. Also, other parts of the kernel might want to access
> to this initial definition (e.g., emulation code for User-Mode Instruction

s/to //

> Prevention uses this state to provide a sane dummy value for CR0 when
> emulating the smsw instruction). Thus, relocate this definition to a
> header file from which it can be conveniently accessed.
> 
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Brian Gerst <brgerst@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> Suggested-by: Borislav Petkov <bp@xxxxxxxxx>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/uapi/asm/processor-flags.h | 6 ++++++
>  arch/x86/kernel/head_32.S                   | 3 ---
>  arch/x86/kernel/head_64.S                   | 3 ---
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h
> index 185f3d10c194..aae1f2aa7563 100644
> --- a/arch/x86/include/uapi/asm/processor-flags.h
> +++ b/arch/x86/include/uapi/asm/processor-flags.h
> @@ -151,5 +151,11 @@
>  #define CX86_ARR_BASE	0xc4
>  #define CX86_RCR_BASE	0xdc
>  
> +/*
> + * Initial state of CR0 for head_32/64.S
> + */

No need for that comment.

With the minor nitpicks addressed, you can add:

Reviewed-by: Borislav Petkov <bp@xxxxxxx>

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton, HRB 21284 (AG NÃrnberg)
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