Re: [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup

[Yinghai Lu]

On Wed, Nov 10, 2010 at 10:35 AM, Kees Cook <kees.cook@xxxxxxxxxxxxx> wrote:
> The XD_DISABLE-clearing side-effect needs to happen for both 32bit
> and 64bit, but the 32bit init routines were not calling verify_cpu()
> yet. This adds that call to gain the side-effect.
>
> The longmode/SSE tests being performed in verify_cpu() need to happen very
> early for 64bit but not for 32bit. Instead of including it in two places
> for 32bit, we can just include it once in arch/x86/kernel/head_32.S.
>
> Signed-off-by: Kees Cook <kees.cook@xxxxxxxxxxxxx>
> Acked-by: Pekka Enberg <penberg@xxxxxxxxxx>
> Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/head_32.S    |    6 ++++++
>  arch/x86/kernel/verify_cpu.S |    1 +
>  2 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
> index bcece91..fdaea52 100644
> --- a/arch/x86/kernel/head_32.S
> +++ b/arch/x86/kernel/head_32.S
> @@ -314,6 +314,10 @@ ENTRY(startup_32_smp)
>        subl $0x80000001, %eax
>        cmpl $(0x8000ffff-0x80000001), %eax
>        ja 6f
> +
> +       /* Clear bogus XD_DISABLE bits */
> +       call verify_cpu
> +
>        mov $0x80000001, %eax
>        cpuid
>        /* Execute Disable bit supported? */
> @@ -609,6 +613,8 @@ ignore_int:
>  #endif
>        iret
>
> +#include "verify_cpu.S"
> +
>        __REFDATA
>  .align 4
>  ENTRY(initial_code)
> diff --git a/arch/x86/kernel/verify_cpu.S b/arch/x86/kernel/verify_cpu.S
> index ccb4136..5644b4b 100644
> --- a/arch/x86/kernel/verify_cpu.S
> +++ b/arch/x86/kernel/verify_cpu.S
> @@ -19,6 +19,7 @@
>  *
>  *     arch/x86_64/boot/compressed/head_64.S: Boot cpu verification
>  *     arch/x86_64/kernel/trampoline_64.S: secondary processor verfication
> + *     arch/x86_64/kernel/head_32.S: processor startup

should change those x86_64 to x86.

Yinghai
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