On Tue, 2020-02-25 at 12:59 -0800, Kees Cook wrote:

On Wed, Feb 05, 2020 at 10:19:23AM -0800, Yu-cheng Yu wrote:

quoted

This patch implements THP Shadow Stack (SHSTK) copying in the same way as
in the previous patch for regular PTE.

In copy_huge_pmd(), clear the dirty bit from the PMD to cause a page fault
upon the next SHSTK access to the PMD.  At that time, fix the PMD and
copy/re-use the page.

Now is as good a time as any to ask: do you have selftests for all this?
It seems like it would be really nice to have a way to verify SHSTK is
working correctly.

Yes, I have some simple tests at https://github.com/yyu168/cet-smoke-test.
I also run Linux/tools/testing/selftests/x86 and GLIBC tests with CET and THP
combinations.

Yu-cheng