ioctl_userfaultfd.2: Add UFFD_FEATURE_EXACT_ADDRESS

Describe the new UFFD_FEATURE_EXACT_ADDRESS API feature.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2
index 06e754cea0c9f3f8c42759f54341a34b776df1c6..3f851f51b93b492cfa1070809a8b5c4517b1284d 100644 (file)
--- a/man2/ioctl_userfaultfd.2
+++ b/man2/ioctl_userfaultfd.2
@@ -207,6 +207,14 @@ in minor mode on hugetlbfs-backed memory areas.
 If this feature bit is set,
 the kernel supports registering userfaultfd ranges
 in minor mode on shmem-backed memory areas.
+.TP
+.BR UFFD_FEATURE_EXACT_ADDRESS " (since Linux 5.18)"
+If this feature bit is set,
+.I uffd_msg.pagefault.address
+will be set to the exact page-fault address that was reported by the hardware,
+and will not mask the offset within the page.
+Note that old Linux versions might indicate the exact address as well,
+even though the feature bit is not set.
 .PP
 The returned
 .I ioctls