[v2] UBUNTU: SAUCE: [x86] fix report of cs-limit nx-emulation

This is a correction to the patch titled "UBUNTU: SAUCE: [x86] implement
cs-limit nx-emulation for ia32" so that NX capabilities are correctly
reported based on actual hardware and arch details.

BugLink: http://bugs.launchpad.net/bugs/454285

Signed-off-by: Kees Cook <kees.cook@canonical.com>
---
 arch/x86/mm/init.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

Kees Cook wrote:
> This is a correction to the patch titled "UBUNTU: SAUCE: [x86] implement
> cs-limit nx-emulation for ia32" so that NX capabilities are correctly
> reported based on actual hardware and arch details.
> 
> BugLink: http://bugs.launchpad.net/bugs/454285
> 
> Signed-off-by: Kees Cook <kees.cook@canonical.com>
> ---
>  arch/x86/mm/init.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index 10de7ed..2044967 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -77,6 +77,7 @@ static void __init set_nx(void)
>  #else
>  static inline void set_nx(void)
>  {
> +	nx_enabled = ( (__supported_pte_mask & _PAGE_NX) == _PAGE_NX );
>  }
>  #endif
>  
> @@ -213,8 +214,13 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
>  	if (nx_enabled)
>  		printk(KERN_INFO "NX (Execute Disable) protection: active\n");
>  	else
> +#ifdef CONFIG_X86_32
>  		printk(KERN_INFO "Using x86 segment limits to approximate "
>  			"NX protection\n");
> +#else
> +		printk(KERN_WARNING "Warning: NX (Execute Disable) protection "
> +			"missing in CPU or disabled in BIOS!\n");
> +#endif
>  
>  	/* Enable PSE if available */
>  	if (cpu_has_pse)

Applied - would you submit a similar patch upstream for 2.6.32 if you 
haven't already ? (note that stuff has moved around a bit).

rtg

Hi Tim,

On Mon, Oct 19, 2009 at 10:45:26AM -0400, Tim Gardner wrote:
> Kees Cook wrote:
> >This is a correction to the patch titled "UBUNTU: SAUCE: [x86] implement
> >cs-limit nx-emulation for ia32" so that NX capabilities are correctly
> >reported based on actual hardware and arch details.
>
> Applied - would you submit a similar patch upstream for 2.6.32 if
> you haven't already ? (note that stuff has moved around a bit).

Yup, this was my plan.

Thanks!

-Kees

On Mon, Oct 19, 2009 at 10:45:26AM -0400, Tim Gardner wrote:
> Applied - would you submit a similar patch upstream for 2.6.32 if
> you haven't already ? (note that stuff has moved around a bit).

http://lkml.org/lkml/2009/10/19/228