Re: [PATCH v10 01/26] Documentation/x86: Add CET description

[Peter Zijlstra]

On Sat, May 16, 2020 at 03:09:22PM +0100, Andrew Cooper wrote:

> Sadly, the same is not true for kernel shadow stacks.
> 
> SSP is 0 after SYSCALL, SYSENTER and CLRSSBSY, and you've got to be
> careful to re-establish the shadow stack before a CALL, interrupt or
> exception tries pushing a word onto the shadow stack at 0xfffffffffffffff8.

Oh man, I can only imagine the joy that brings to #NM and friends :-(