On Tue, 2020-02-25 at 13:10 -0800, Kees Cook wrote:

On Wed, Feb 05, 2020 at 10:19:26AM -0800, Yu-cheng Yu wrote:

quoted

WRUSS is a new kernel-mode instruction but writes directly to user Shadow
Stack (SHSTK) memory.  This is used to construct a return address on SHSTK
for the signal handler.

This instruction can fault if the user SHSTK is not valid SHSTK memory.
In that case, the kernel does a fixup.

Since these functions aren't used in this patch, should this get merged
with patch 19?

Yes, I can do that.

Yu-cheng