userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers

Implement helpers methods to invoke userfaultfd wp faults more
selectively: not only when a wp fault triggers on a vma with
vma->vm_flags VM_UFFD_WP set, but only if the _PAGE_UFFD_WP bit is set
in the pagetable too.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
1 file changed