[PATCH v2 5/6] UFFDIO_REGISTER.2const: Document UFFDIO_REGISTER_MODE_RWP and 1 << _UFFDIO_RWPROTECT

Add the new registration mode bit introduced in Linux 7.2:

  UFFDIO_REGISTER_MODE_RWP   Track every access (read or write) to a
                             present page in the registered range.
                             Cannot be combined with
                             UFFDIO_REGISTER_MODE_WP; both modes share
                             the same per-PTE marker bit. Anonymous,
                             shmem, and hugetlbfs ranges are
                             compatible.

Also document the matching argp->ioctls bit, 1 << _UFFDIO_RWPROTECT,
which the kernel reports only when the range was registered with
UFFDIO_REGISTER_MODE_RWP (which itself requires UFFD_FEATURE_RWP to
have been negotiated).

Signed-off-by: Kiryl Shutsemau <[email protected]>
Acked-by: Mike Rapoport (Microsoft) <[email protected]>
---
 man/man2const/UFFDIO_REGISTER.2const | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/man/man2const/UFFDIO_REGISTER.2const b/man/man2const/UFFDIO_REGISTER.2const
index 50064c954b81..ded57cf301ad 100644
--- a/man/man2const/UFFDIO_REGISTER.2const
+++ b/man/man2const/UFFDIO_REGISTER.2const
@@ -72,6 +72,20 @@ .SH DESCRIPTION
 only hugetlbfs ranges are compatible.
 Since Linux 5.14,
 compatibility with shmem ranges was added.
+.TP
+.BR UFFDIO_REGISTER_MODE_RWP " (since Linux 7.2)"
+Track page faults on read-write-protected pages.
+Every access
+(read or write)
+to a page present within the registered range
+generates a notification
+once the range has been protected with
+.BR UFFDIO_RWPROTECT (2const).
+This mode cannot be combined with
+.BR UFFDIO_REGISTER_MODE_WP ;
+attempting to do so fails with
+.BR EINVAL .
+Anonymous, shmem, and hugetlbfs ranges are compatible.
 .P
 If the operation is successful, the kernel modifies the
 .I argp->ioctls
@@ -109,6 +123,16 @@ .SH DESCRIPTION
 The
 .B UFFDIO_POISON
 operation is supported.
+.TP
+.BR "1 << _UFFDIO_RWPROTECT" " (since Linux 7.2)"
+The
+.B UFFDIO_RWPROTECT
+operation is supported.
+This bit is reported only when the range was registered with
+.B UFFDIO_REGISTER_MODE_RWP
+(which itself requires
+.B UFFD_FEATURE_RWP
+to have been negotiated).
 .SH RETURN VALUE
 On success,
 0 is returned.
-- 
2.54.0