diff --git a/libc/kernel/uapi/linux/userfaultfd.h b/libc/kernel/uapi/linux/userfaultfd.h
new file mode 100644
index 0000000..e4e0998
--- /dev/null
+++ b/libc/kernel/uapi/linux/userfaultfd.h
@@ -0,0 +1,106 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef _LINUX_USERFAULTFD_H
+#define _LINUX_USERFAULTFD_H
+#include <linux/types.h>
+#define UFFD_API ((__u64) 0xAA)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define UFFD_API_FEATURES (0)
+#define UFFD_API_IOCTLS ((__u64) 1 << _UFFDIO_REGISTER | (__u64) 1 << _UFFDIO_UNREGISTER | (__u64) 1 << _UFFDIO_API)
+#define UFFD_API_RANGE_IOCTLS ((__u64) 1 << _UFFDIO_WAKE | (__u64) 1 << _UFFDIO_COPY | (__u64) 1 << _UFFDIO_ZEROPAGE)
+#define _UFFDIO_REGISTER (0x00)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define _UFFDIO_UNREGISTER (0x01)
+#define _UFFDIO_WAKE (0x02)
+#define _UFFDIO_COPY (0x03)
+#define _UFFDIO_ZEROPAGE (0x04)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define _UFFDIO_API (0x3F)
+#define UFFDIO 0xAA
+#define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, struct uffdio_api)
+#define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, struct uffdio_register)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, struct uffdio_range)
+#define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, struct uffdio_range)
+#define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, struct uffdio_copy)
+#define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, struct uffdio_zeropage)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+struct uffd_msg {
+  __u8 event;
+  __u8 reserved1;
+  __u16 reserved2;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+  __u32 reserved3;
+  union {
+    struct {
+      __u64 flags;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+      __u64 address;
+    } pagefault;
+    struct {
+      __u64 reserved1;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+      __u64 reserved2;
+      __u64 reserved3;
+    } reserved;
+  } arg;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+} __packed;
+#define UFFD_EVENT_PAGEFAULT 0x12
+#define UFFD_PAGEFAULT_FLAG_WRITE (1 << 0)
+#define UFFD_PAGEFAULT_FLAG_WP (1 << 1)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+struct uffdio_api {
+  __u64 api;
+  __u64 features;
+  __u64 ioctls;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+};
+struct uffdio_range {
+  __u64 start;
+  __u64 len;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+};
+struct uffdio_register {
+  struct uffdio_range range;
+#define UFFDIO_REGISTER_MODE_MISSING ((__u64) 1 << 0)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define UFFDIO_REGISTER_MODE_WP ((__u64) 1 << 1)
+  __u64 mode;
+  __u64 ioctls;
+};
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+struct uffdio_copy {
+  __u64 dst;
+  __u64 src;
+  __u64 len;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define UFFDIO_COPY_MODE_DONTWAKE ((__u64) 1 << 0)
+  __u64 mode;
+  __s64 copy;
+};
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+struct uffdio_zeropage {
+  struct uffdio_range range;
+#define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64) 1 << 0)
+  __u64 mode;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+  __s64 zeropage;
+};
+#endif