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SubjectRe: [PATCH 21/34] x86, pkeys: dump PKRU with other kernel registers
On Thu, 3 Dec 2015, Dave Hansen wrote:

>
> From: Dave Hansen <dave.hansen@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 <tglx@linutronix.de>

> Signed-off-by: Dave Hansen <dave.hansen@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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