[PATCH 18/21] userfaultfd: UFFDIO_REMAP uABI

Andrea Arcangeli
2015-03-05T17:18:01Z

This implements the uABI of UFFDIO_REMAP.

Notably one mode bitflag is also forwarded (and in turn known) by the
lowlevel remap_pages method.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
include/uapi/linux/userfaultfd.h | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 61251e6..db6e99a 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -19,7 +19,8 @@
#define UFFD_API_RANGE_IOCTLS \
((__u64)1 << _UFFDIO_WAKE | \
(__u64)1 << _UFFDIO_COPY | \
- (__u64)1 << _UFFDIO_ZEROPAGE)
+ (__u64)1 << _UFFDIO_ZEROPAGE | \
+ (__u64)1 << _UFFDIO_REMAP)

/*
* Valid ioctl command number range with this API is from 0x00 to
@@ -34,6 +35,7 @@
#define _UFFDIO_WAKE (0x02)
#define _UFFDIO_COPY (0x03)
#define _UFFDIO_ZEROPAGE (0x04)
+#define _UFFDIO_REMAP (0x05)
#define _UFFDIO_API (0x3F)

/* userfaultfd ioctl ids */
@@ -50,6 +52,8 @@
struct uffdio_copy)
#define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
struct uffdio_zeropage)
+#define UFFDIO_REMAP _IOWR(UFFDIO, _UFFDIO_REMAP, \
+ struct uffdio_remap)

/*
* Valid bits below PAGE_SHIFT in the userfault address read through
@@ -122,4 +126,25 @@ struct uffdio_zeropage {
__s64 wake;
};

+struct uffdio_remap {
+ __u64 dst;
+ __u64 src;
+ __u64 len;
+ /*
+ * Especially if used to atomically remove memory from the
+ * address space the wake on the dst range is not needed.
+ */
+#define UFFDIO_REMAP_MODE_DONTWAKE ((__u64)1<<0)
+#define UFFDIO_REMAP_MODE_ALLOW_SRC_HOLES ((__u64)1<<1)
+ __u64 mode;
+
+ /*
+ * "remap" and "wake" are written by the ioctl and must be at
+ * the end: the copy_from_user will not read the last 16
+ * bytes.
+ */
+ __s64 remap;
+ __s64 wake;
+};
+
#endif /* _LINUX_USERFAULTFD_H */