userfaultfd: non-cooperative: add mremap() event
The event denotes that an area [start:end] moves to different location.
Length change isn't reported as "new" addresses, if they appear on the
uffd reader side they will not contain any data and the latter can just
zeromap them.
Waiting for the event ACK is also done outside of mmap sem, as for fork
event.
Link: http://lkml.kernel.org/r/20161216144821.5183-12-aarcange@redhat.com
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index c8953c8..79a85e5 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -18,7 +18,8 @@
* means the userland is reading).
*/
#define UFFD_API ((__u64)0xAA)
-#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK)
+#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \
+ UFFD_FEATURE_EVENT_REMAP)
#define UFFD_API_IOCTLS \
((__u64)1 << _UFFDIO_REGISTER | \
(__u64)1 << _UFFDIO_UNREGISTER | \
@@ -77,6 +78,12 @@ struct uffd_msg {
} fork;
struct {
+ __u64 from;
+ __u64 to;
+ __u64 len;
+ } remap;
+
+ struct {
/* unused reserved fields */
__u64 reserved1;
__u64 reserved2;
@@ -90,6 +97,7 @@ struct uffd_msg {
*/
#define UFFD_EVENT_PAGEFAULT 0x12
#define UFFD_EVENT_FORK 0x13
+#define UFFD_EVENT_REMAP 0x14
/* flags for UFFD_EVENT_PAGEFAULT */
#define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
@@ -110,6 +118,7 @@ struct uffdio_api {
*/
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
#define UFFD_FEATURE_EVENT_FORK (1<<1)
+#define UFFD_FEATURE_EVENT_REMAP (1<<2)
__u64 features;
__u64 ioctls;