Re: Is espfix64's double-fault thing OK on Xen?

From: H. Peter Anvin
Date: Mon Jul 14 2014 - 13:08:37 EST


On 07/09/2014 04:17 PM, Andy Lutomirski wrote:
> This part in __do_double_fault looks fishy:
>
> cmpl $__KERNEL_CS,CS(%rdi)
> jne do_double_fault
>
> Shouldn't that be:
>
> test $3,CS(%rdi)
> jnz do_double_fault
>

No, it should be fine. The *only* case where we need to do the espfix
magic is when we are on __KERNEL_CS.

-hpa


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