Re: [RFC PATCH v9 06/27] mm: Introduce VM_SHSTK for Shadow Stack memory

On 2/5/20 10:19 AM, Yu-cheng Yu wrote:

A Shadow Stack (SHSTK) PTE must be read-only and have _PAGE_DIRTY set.
However, read-only and Dirty PTEs also exist for copy-on-write (COW) pages.
These two cases are handled differently for page faults and a new VM flag
is necessary for tracking SHSTK VMAs.

v9:
- Add VM_SHSTK case to arch_vma_name().
- Revise the commit log to explain why a new VM flag is needed.

To be honest, a flag is not strictly *needed*.  It is certainly
convenient and straightforward, but it's far from being truly necessary.