1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
2 | /* |
3 | * include/linux/userfaultfd.h |
4 | * |
5 | * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> |
6 | * Copyright (C) 2015 Red Hat, Inc. |
7 | * |
8 | */ |
9 | |
10 | #ifndef _LINUX_USERFAULTFD_H |
11 | #define _LINUX_USERFAULTFD_H |
12 | |
13 | #include <linux/types.h> |
14 | |
15 | /* |
16 | * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and |
17 | * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In |
18 | * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ |
19 | * means the userland is reading). |
20 | */ |
21 | #define UFFD_API ((__u64)0xAA) |
22 | #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \ |
23 | UFFD_FEATURE_EVENT_REMAP | \ |
24 | UFFD_FEATURE_EVENT_REMOVE | \ |
25 | UFFD_FEATURE_EVENT_UNMAP | \ |
26 | UFFD_FEATURE_MISSING_HUGETLBFS | \ |
27 | UFFD_FEATURE_MISSING_SHMEM | \ |
28 | UFFD_FEATURE_SIGBUS | \ |
29 | UFFD_FEATURE_THREAD_ID) |
30 | #define UFFD_API_IOCTLS \ |
31 | ((__u64)1 << _UFFDIO_REGISTER | \ |
32 | (__u64)1 << _UFFDIO_UNREGISTER | \ |
33 | (__u64)1 << _UFFDIO_API) |
34 | #define UFFD_API_RANGE_IOCTLS \ |
35 | ((__u64)1 << _UFFDIO_WAKE | \ |
36 | (__u64)1 << _UFFDIO_COPY | \ |
37 | (__u64)1 << _UFFDIO_ZEROPAGE) |
38 | #define UFFD_API_RANGE_IOCTLS_BASIC \ |
39 | ((__u64)1 << _UFFDIO_WAKE | \ |
40 | (__u64)1 << _UFFDIO_COPY) |
41 | |
42 | /* |
43 | * Valid ioctl command number range with this API is from 0x00 to |
44 | * 0x3F. UFFDIO_API is the fixed number, everything else can be |
45 | * changed by implementing a different UFFD_API. If sticking to the |
46 | * same UFFD_API more ioctl can be added and userland will be aware of |
47 | * which ioctl the running kernel implements through the ioctl command |
48 | * bitmask written by the UFFDIO_API. |
49 | */ |
50 | #define _UFFDIO_REGISTER (0x00) |
51 | #define _UFFDIO_UNREGISTER (0x01) |
52 | #define _UFFDIO_WAKE (0x02) |
53 | #define _UFFDIO_COPY (0x03) |
54 | #define _UFFDIO_ZEROPAGE (0x04) |
55 | #define _UFFDIO_API (0x3F) |
56 | |
57 | /* userfaultfd ioctl ids */ |
58 | #define UFFDIO 0xAA |
59 | #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \ |
60 | struct uffdio_api) |
61 | #define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \ |
62 | struct uffdio_register) |
63 | #define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \ |
64 | struct uffdio_range) |
65 | #define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \ |
66 | struct uffdio_range) |
67 | #define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \ |
68 | struct uffdio_copy) |
69 | #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \ |
70 | struct uffdio_zeropage) |
71 | |
72 | /* read() structure */ |
73 | struct uffd_msg { |
74 | __u8 event; |
75 | |
76 | __u8 reserved1; |
77 | __u16 reserved2; |
78 | __u32 reserved3; |
79 | |
80 | union { |
81 | struct { |
82 | __u64 flags; |
83 | __u64 address; |
84 | union { |
85 | __u32 ptid; |
86 | } feat; |
87 | } pagefault; |
88 | |
89 | struct { |
90 | __u32 ufd; |
91 | } fork; |
92 | |
93 | struct { |
94 | __u64 from; |
95 | __u64 to; |
96 | __u64 len; |
97 | } remap; |
98 | |
99 | struct { |
100 | __u64 start; |
101 | __u64 end; |
102 | } remove; |
103 | |
104 | struct { |
105 | /* unused reserved fields */ |
106 | __u64 reserved1; |
107 | __u64 reserved2; |
108 | __u64 reserved3; |
109 | } reserved; |
110 | } arg; |
111 | } __attribute__((packed)); |
112 | |
113 | /* |
114 | * Start at 0x12 and not at 0 to be more strict against bugs. |
115 | */ |
116 | #define UFFD_EVENT_PAGEFAULT 0x12 |
117 | #define UFFD_EVENT_FORK 0x13 |
118 | #define UFFD_EVENT_REMAP 0x14 |
119 | #define UFFD_EVENT_REMOVE 0x15 |
120 | #define UFFD_EVENT_UNMAP 0x16 |
121 | |
122 | /* flags for UFFD_EVENT_PAGEFAULT */ |
123 | #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */ |
124 | #define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */ |
125 | |
126 | struct uffdio_api { |
127 | /* userland asks for an API number and the features to enable */ |
128 | __u64 api; |
129 | /* |
130 | * Kernel answers below with the all available features for |
131 | * the API, this notifies userland of which events and/or |
132 | * which flags for each event are enabled in the current |
133 | * kernel. |
134 | * |
135 | * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE |
136 | * are to be considered implicitly always enabled in all kernels as |
137 | * long as the uffdio_api.api requested matches UFFD_API. |
138 | * |
139 | * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER |
140 | * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on |
141 | * hugetlbfs virtual memory ranges. Adding or not adding |
142 | * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has |
143 | * no real functional effect after UFFDIO_API returns, but |
144 | * it's only useful for an initial feature set probe at |
145 | * UFFDIO_API time. There are two ways to use it: |
146 | * |
147 | * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the |
148 | * uffdio_api.features before calling UFFDIO_API, an error |
149 | * will be returned by UFFDIO_API on a kernel without |
150 | * hugetlbfs missing support |
151 | * |
152 | * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in |
153 | * uffdio_api.features and instead it will be set by the |
154 | * kernel in the uffdio_api.features if the kernel supports |
155 | * it, so userland can later check if the feature flag is |
156 | * present in uffdio_api.features after UFFDIO_API |
157 | * succeeded. |
158 | * |
159 | * UFFD_FEATURE_MISSING_SHMEM works the same as |
160 | * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem |
161 | * (i.e. tmpfs and other shmem based APIs). |
162 | * |
163 | * UFFD_FEATURE_SIGBUS feature means no page-fault |
164 | * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead |
165 | * a SIGBUS signal will be sent to the faulting process. |
166 | * |
167 | * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will |
168 | * be returned, if feature is not requested 0 will be returned. |
169 | */ |
170 | #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) |
171 | #define UFFD_FEATURE_EVENT_FORK (1<<1) |
172 | #define UFFD_FEATURE_EVENT_REMAP (1<<2) |
173 | #define UFFD_FEATURE_EVENT_REMOVE (1<<3) |
174 | #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4) |
175 | #define UFFD_FEATURE_MISSING_SHMEM (1<<5) |
176 | #define UFFD_FEATURE_EVENT_UNMAP (1<<6) |
177 | #define UFFD_FEATURE_SIGBUS (1<<7) |
178 | #define UFFD_FEATURE_THREAD_ID (1<<8) |
179 | __u64 features; |
180 | |
181 | __u64 ioctls; |
182 | }; |
183 | |
184 | struct uffdio_range { |
185 | __u64 start; |
186 | __u64 len; |
187 | }; |
188 | |
189 | struct uffdio_register { |
190 | struct uffdio_range range; |
191 | #define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0) |
192 | #define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1) |
193 | __u64 mode; |
194 | |
195 | /* |
196 | * kernel answers which ioctl commands are available for the |
197 | * range, keep at the end as the last 8 bytes aren't read. |
198 | */ |
199 | __u64 ioctls; |
200 | }; |
201 | |
202 | struct uffdio_copy { |
203 | __u64 dst; |
204 | __u64 src; |
205 | __u64 len; |
206 | /* |
207 | * There will be a wrprotection flag later that allows to map |
208 | * pages wrprotected on the fly. And such a flag will be |
209 | * available if the wrprotection ioctl are implemented for the |
210 | * range according to the uffdio_register.ioctls. |
211 | */ |
212 | #define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0) |
213 | __u64 mode; |
214 | |
215 | /* |
216 | * "copy" is written by the ioctl and must be at the end: the |
217 | * copy_from_user will not read the last 8 bytes. |
218 | */ |
219 | __s64 copy; |
220 | }; |
221 | |
222 | struct uffdio_zeropage { |
223 | struct uffdio_range range; |
224 | #define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0) |
225 | __u64 mode; |
226 | |
227 | /* |
228 | * "zeropage" is written by the ioctl and must be at the end: |
229 | * the copy_from_user will not read the last 8 bytes. |
230 | */ |
231 | __s64 zeropage; |
232 | }; |
233 | |
234 | #endif /* _LINUX_USERFAULTFD_H */ |
235 | |