2 * include/linux/userfaultfd.h
4 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
5 * Copyright (C) 2015 Red Hat, Inc.
9 #ifndef _LINUX_USERFAULTFD_H
10 #define _LINUX_USERFAULTFD_H
12 #include <linux/types.h>
15 * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
16 * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In
17 * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
18 * means the userland is reading).
20 #define UFFD_API ((__u64)0xAA)
21 #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK)
22 #define UFFD_API_IOCTLS \
23 ((__u64)1 << _UFFDIO_REGISTER | \
24 (__u64)1 << _UFFDIO_UNREGISTER | \
25 (__u64)1 << _UFFDIO_API)
26 #define UFFD_API_RANGE_IOCTLS \
27 ((__u64)1 << _UFFDIO_WAKE | \
28 (__u64)1 << _UFFDIO_COPY | \
29 (__u64)1 << _UFFDIO_ZEROPAGE)
32 * Valid ioctl command number range with this API is from 0x00 to
33 * 0x3F. UFFDIO_API is the fixed number, everything else can be
34 * changed by implementing a different UFFD_API. If sticking to the
35 * same UFFD_API more ioctl can be added and userland will be aware of
36 * which ioctl the running kernel implements through the ioctl command
37 * bitmask written by the UFFDIO_API.
39 #define _UFFDIO_REGISTER (0x00)
40 #define _UFFDIO_UNREGISTER (0x01)
41 #define _UFFDIO_WAKE (0x02)
42 #define _UFFDIO_COPY (0x03)
43 #define _UFFDIO_ZEROPAGE (0x04)
44 #define _UFFDIO_API (0x3F)
46 /* userfaultfd ioctl ids */
48 #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \
50 #define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \
51 struct uffdio_register)
52 #define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \
54 #define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \
56 #define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \
58 #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
59 struct uffdio_zeropage)
61 /* read() structure */
80 /* unused reserved fields */
89 * Start at 0x12 and not at 0 to be more strict against bugs.
91 #define UFFD_EVENT_PAGEFAULT 0x12
92 #define UFFD_EVENT_FORK 0x13
94 /* flags for UFFD_EVENT_PAGEFAULT */
95 #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
96 #define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */
99 /* userland asks for an API number and the features to enable */
102 * Kernel answers below with the all available features for
103 * the API, this notifies userland of which events and/or
104 * which flags for each event are enabled in the current
107 * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
108 * are to be considered implicitly always enabled in all kernels as
109 * long as the uffdio_api.api requested matches UFFD_API.
111 #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
112 #define UFFD_FEATURE_EVENT_FORK (1<<1)
118 struct uffdio_range {
123 struct uffdio_register {
124 struct uffdio_range range;
125 #define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0)
126 #define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1)
130 * kernel answers which ioctl commands are available for the
131 * range, keep at the end as the last 8 bytes aren't read.
141 * There will be a wrprotection flag later that allows to map
142 * pages wrprotected on the fly. And such a flag will be
143 * available if the wrprotection ioctl are implemented for the
144 * range according to the uffdio_register.ioctls.
146 #define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0)
150 * "copy" is written by the ioctl and must be at the end: the
151 * copy_from_user will not read the last 8 bytes.
156 struct uffdio_zeropage {
157 struct uffdio_range range;
158 #define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0)
162 * "zeropage" is written by the ioctl and must be at the end:
163 * the copy_from_user will not read the last 8 bytes.
168 #endif /* _LINUX_USERFAULTFD_H */