On Thu, 3 Dec 2015, Dave Hansen wrote:

> 
> From: Dave Hansen <dave.han...@linux.intel.com>
> 
> I'm a bit ambivalent about whether this is needed or not.
>
> Protection Keys never affect kernel mappings.  But, they can
> affect whether the kernel will fault when it touches a user
> mapping.  But, the kernel doesn't touch user mappings without
> some careful choreography and these accesses don't generally
> result in oopses.

Well, if we miss some careful choreography at some place, this
information is going to be helpful.

Reviewed-by: Thomas Gleixner <t...@linutronix.de>
 
> Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
> ---
> 
>  b/arch/x86/kernel/process_64.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff -puN arch/x86/kernel/process_64.c~pkeys-30-kernel-error-dumps 
> arch/x86/kernel/process_64.c
> --- a/arch/x86/kernel/process_64.c~pkeys-30-kernel-error-dumps        
> 2015-12-03 16:21:27.874773264 -0800
> +++ b/arch/x86/kernel/process_64.c    2015-12-03 16:21:27.877773400 -0800
> @@ -116,6 +116,8 @@ void __show_regs(struct pt_regs *regs, i
>       printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, 
> d2);
>       printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, 
> d7);
>  
> +     if (boot_cpu_has(X86_FEATURE_OSPKE))
> +             printk(KERN_DEFAULT "PKRU: %08x\n", read_pkru());
>  }
>  
>  void release_thread(struct task_struct *dead_task)
> _
> 
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