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 | /* ioctls for /dev/userfaultfd */ |
16 | #define USERFAULTFD_IOC 0xAA |
17 | #define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00) |
18 | |
19 | /* |
20 | * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and |
21 | * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In |
22 | * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ |
23 | * means the userland is reading). |
24 | */ |
25 | #define UFFD_API ((__u64)0xAA) |
26 | #define UFFD_API_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING | \ |
27 | UFFDIO_REGISTER_MODE_WP | \ |
28 | UFFDIO_REGISTER_MODE_MINOR) |
29 | #define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \ |
30 | UFFD_FEATURE_EVENT_FORK | \ |
31 | UFFD_FEATURE_EVENT_REMAP | \ |
32 | UFFD_FEATURE_EVENT_REMOVE | \ |
33 | UFFD_FEATURE_EVENT_UNMAP | \ |
34 | UFFD_FEATURE_MISSING_HUGETLBFS | \ |
35 | UFFD_FEATURE_MISSING_SHMEM | \ |
36 | UFFD_FEATURE_SIGBUS | \ |
37 | UFFD_FEATURE_THREAD_ID | \ |
38 | UFFD_FEATURE_MINOR_HUGETLBFS | \ |
39 | UFFD_FEATURE_MINOR_SHMEM | \ |
40 | UFFD_FEATURE_EXACT_ADDRESS | \ |
41 | UFFD_FEATURE_WP_HUGETLBFS_SHMEM | \ |
42 | UFFD_FEATURE_WP_UNPOPULATED | \ |
43 | UFFD_FEATURE_POISON | \ |
44 | UFFD_FEATURE_WP_ASYNC | \ |
45 | UFFD_FEATURE_MOVE) |
46 | #define UFFD_API_IOCTLS \ |
47 | ((__u64)1 << _UFFDIO_REGISTER | \ |
48 | (__u64)1 << _UFFDIO_UNREGISTER | \ |
49 | (__u64)1 << _UFFDIO_API) |
50 | #define UFFD_API_RANGE_IOCTLS \ |
51 | ((__u64)1 << _UFFDIO_WAKE | \ |
52 | (__u64)1 << _UFFDIO_COPY | \ |
53 | (__u64)1 << _UFFDIO_ZEROPAGE | \ |
54 | (__u64)1 << _UFFDIO_MOVE | \ |
55 | (__u64)1 << _UFFDIO_WRITEPROTECT | \ |
56 | (__u64)1 << _UFFDIO_CONTINUE | \ |
57 | (__u64)1 << _UFFDIO_POISON) |
58 | #define UFFD_API_RANGE_IOCTLS_BASIC \ |
59 | ((__u64)1 << _UFFDIO_WAKE | \ |
60 | (__u64)1 << _UFFDIO_COPY | \ |
61 | (__u64)1 << _UFFDIO_WRITEPROTECT | \ |
62 | (__u64)1 << _UFFDIO_CONTINUE | \ |
63 | (__u64)1 << _UFFDIO_POISON) |
64 | |
65 | /* |
66 | * Valid ioctl command number range with this API is from 0x00 to |
67 | * 0x3F. UFFDIO_API is the fixed number, everything else can be |
68 | * changed by implementing a different UFFD_API. If sticking to the |
69 | * same UFFD_API more ioctl can be added and userland will be aware of |
70 | * which ioctl the running kernel implements through the ioctl command |
71 | * bitmask written by the UFFDIO_API. |
72 | */ |
73 | #define _UFFDIO_REGISTER (0x00) |
74 | #define _UFFDIO_UNREGISTER (0x01) |
75 | #define _UFFDIO_WAKE (0x02) |
76 | #define _UFFDIO_COPY (0x03) |
77 | #define _UFFDIO_ZEROPAGE (0x04) |
78 | #define _UFFDIO_MOVE (0x05) |
79 | #define _UFFDIO_WRITEPROTECT (0x06) |
80 | #define _UFFDIO_CONTINUE (0x07) |
81 | #define _UFFDIO_POISON (0x08) |
82 | #define _UFFDIO_API (0x3F) |
83 | |
84 | /* userfaultfd ioctl ids */ |
85 | #define UFFDIO 0xAA |
86 | #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \ |
87 | struct uffdio_api) |
88 | #define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \ |
89 | struct uffdio_register) |
90 | #define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \ |
91 | struct uffdio_range) |
92 | #define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \ |
93 | struct uffdio_range) |
94 | #define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \ |
95 | struct uffdio_copy) |
96 | #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \ |
97 | struct uffdio_zeropage) |
98 | #define UFFDIO_MOVE _IOWR(UFFDIO, _UFFDIO_MOVE, \ |
99 | struct uffdio_move) |
100 | #define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \ |
101 | struct uffdio_writeprotect) |
102 | #define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, \ |
103 | struct uffdio_continue) |
104 | #define UFFDIO_POISON _IOWR(UFFDIO, _UFFDIO_POISON, \ |
105 | struct uffdio_poison) |
106 | |
107 | /* read() structure */ |
108 | struct uffd_msg { |
109 | __u8 event; |
110 | |
111 | __u8 reserved1; |
112 | __u16 reserved2; |
113 | __u32 reserved3; |
114 | |
115 | union { |
116 | struct { |
117 | __u64 flags; |
118 | __u64 address; |
119 | union { |
120 | __u32 ptid; |
121 | } feat; |
122 | } pagefault; |
123 | |
124 | struct { |
125 | __u32 ufd; |
126 | } fork; |
127 | |
128 | struct { |
129 | __u64 from; |
130 | __u64 to; |
131 | __u64 len; |
132 | } remap; |
133 | |
134 | struct { |
135 | __u64 start; |
136 | __u64 end; |
137 | } remove; |
138 | |
139 | struct { |
140 | /* unused reserved fields */ |
141 | __u64 reserved1; |
142 | __u64 reserved2; |
143 | __u64 reserved3; |
144 | } reserved; |
145 | } arg; |
146 | } __packed; |
147 | |
148 | /* |
149 | * Start at 0x12 and not at 0 to be more strict against bugs. |
150 | */ |
151 | #define UFFD_EVENT_PAGEFAULT 0x12 |
152 | #define UFFD_EVENT_FORK 0x13 |
153 | #define UFFD_EVENT_REMAP 0x14 |
154 | #define UFFD_EVENT_REMOVE 0x15 |
155 | #define UFFD_EVENT_UNMAP 0x16 |
156 | |
157 | /* flags for UFFD_EVENT_PAGEFAULT */ |
158 | #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */ |
159 | #define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */ |
160 | #define UFFD_PAGEFAULT_FLAG_MINOR (1<<2) /* If reason is VM_UFFD_MINOR */ |
161 | |
162 | struct uffdio_api { |
163 | /* userland asks for an API number and the features to enable */ |
164 | __u64 api; |
165 | /* |
166 | * Kernel answers below with the all available features for |
167 | * the API, this notifies userland of which events and/or |
168 | * which flags for each event are enabled in the current |
169 | * kernel. |
170 | * |
171 | * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE |
172 | * are to be considered implicitly always enabled in all kernels as |
173 | * long as the uffdio_api.api requested matches UFFD_API. |
174 | * |
175 | * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER |
176 | * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on |
177 | * hugetlbfs virtual memory ranges. Adding or not adding |
178 | * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has |
179 | * no real functional effect after UFFDIO_API returns, but |
180 | * it's only useful for an initial feature set probe at |
181 | * UFFDIO_API time. There are two ways to use it: |
182 | * |
183 | * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the |
184 | * uffdio_api.features before calling UFFDIO_API, an error |
185 | * will be returned by UFFDIO_API on a kernel without |
186 | * hugetlbfs missing support |
187 | * |
188 | * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in |
189 | * uffdio_api.features and instead it will be set by the |
190 | * kernel in the uffdio_api.features if the kernel supports |
191 | * it, so userland can later check if the feature flag is |
192 | * present in uffdio_api.features after UFFDIO_API |
193 | * succeeded. |
194 | * |
195 | * UFFD_FEATURE_MISSING_SHMEM works the same as |
196 | * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem |
197 | * (i.e. tmpfs and other shmem based APIs). |
198 | * |
199 | * UFFD_FEATURE_SIGBUS feature means no page-fault |
200 | * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead |
201 | * a SIGBUS signal will be sent to the faulting process. |
202 | * |
203 | * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will |
204 | * be returned, if feature is not requested 0 will be returned. |
205 | * |
206 | * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults |
207 | * can be intercepted (via REGISTER_MODE_MINOR) for |
208 | * hugetlbfs-backed pages. |
209 | * |
210 | * UFFD_FEATURE_MINOR_SHMEM indicates the same support as |
211 | * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead. |
212 | * |
213 | * UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page |
214 | * faults would be provided and the offset within the page would not be |
215 | * masked. |
216 | * |
217 | * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd |
218 | * write-protection mode is supported on both shmem and hugetlbfs. |
219 | * |
220 | * UFFD_FEATURE_WP_UNPOPULATED indicates that userfaultfd |
221 | * write-protection mode will always apply to unpopulated pages |
222 | * (i.e. empty ptes). This will be the default behavior for shmem |
223 | * & hugetlbfs, so this flag only affects anonymous memory behavior |
224 | * when userfault write-protection mode is registered. |
225 | * |
226 | * UFFD_FEATURE_WP_ASYNC indicates that userfaultfd write-protection |
227 | * asynchronous mode is supported in which the write fault is |
228 | * automatically resolved and write-protection is un-set. |
229 | * It implies UFFD_FEATURE_WP_UNPOPULATED. |
230 | * |
231 | * UFFD_FEATURE_MOVE indicates that the kernel supports moving an |
232 | * existing page contents from userspace. |
233 | */ |
234 | #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) |
235 | #define UFFD_FEATURE_EVENT_FORK (1<<1) |
236 | #define UFFD_FEATURE_EVENT_REMAP (1<<2) |
237 | #define UFFD_FEATURE_EVENT_REMOVE (1<<3) |
238 | #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4) |
239 | #define UFFD_FEATURE_MISSING_SHMEM (1<<5) |
240 | #define UFFD_FEATURE_EVENT_UNMAP (1<<6) |
241 | #define UFFD_FEATURE_SIGBUS (1<<7) |
242 | #define UFFD_FEATURE_THREAD_ID (1<<8) |
243 | #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9) |
244 | #define UFFD_FEATURE_MINOR_SHMEM (1<<10) |
245 | #define UFFD_FEATURE_EXACT_ADDRESS (1<<11) |
246 | #define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<12) |
247 | #define UFFD_FEATURE_WP_UNPOPULATED (1<<13) |
248 | #define UFFD_FEATURE_POISON (1<<14) |
249 | #define UFFD_FEATURE_WP_ASYNC (1<<15) |
250 | #define UFFD_FEATURE_MOVE (1<<16) |
251 | __u64 features; |
252 | |
253 | __u64 ioctls; |
254 | }; |
255 | |
256 | struct uffdio_range { |
257 | __u64 start; |
258 | __u64 len; |
259 | }; |
260 | |
261 | struct uffdio_register { |
262 | struct uffdio_range range; |
263 | #define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0) |
264 | #define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1) |
265 | #define UFFDIO_REGISTER_MODE_MINOR ((__u64)1<<2) |
266 | __u64 mode; |
267 | |
268 | /* |
269 | * kernel answers which ioctl commands are available for the |
270 | * range, keep at the end as the last 8 bytes aren't read. |
271 | */ |
272 | __u64 ioctls; |
273 | }; |
274 | |
275 | struct uffdio_copy { |
276 | __u64 dst; |
277 | __u64 src; |
278 | __u64 len; |
279 | #define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0) |
280 | /* |
281 | * UFFDIO_COPY_MODE_WP will map the page write protected on |
282 | * the fly. UFFDIO_COPY_MODE_WP is available only if the |
283 | * write protected ioctl is implemented for the range |
284 | * according to the uffdio_register.ioctls. |
285 | */ |
286 | #define UFFDIO_COPY_MODE_WP ((__u64)1<<1) |
287 | __u64 mode; |
288 | |
289 | /* |
290 | * "copy" is written by the ioctl and must be at the end: the |
291 | * copy_from_user will not read the last 8 bytes. |
292 | */ |
293 | __s64 copy; |
294 | }; |
295 | |
296 | struct uffdio_zeropage { |
297 | struct uffdio_range range; |
298 | #define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0) |
299 | __u64 mode; |
300 | |
301 | /* |
302 | * "zeropage" is written by the ioctl and must be at the end: |
303 | * the copy_from_user will not read the last 8 bytes. |
304 | */ |
305 | __s64 zeropage; |
306 | }; |
307 | |
308 | struct uffdio_writeprotect { |
309 | struct uffdio_range range; |
310 | /* |
311 | * UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range, |
312 | * unset the flag to undo protection of a range which was previously |
313 | * write protected. |
314 | * |
315 | * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up |
316 | * any wait thread after the operation succeeds. |
317 | * |
318 | * NOTE: Write protecting a region (WP=1) is unrelated to page faults, |
319 | * therefore DONTWAKE flag is meaningless with WP=1. Removing write |
320 | * protection (WP=0) in response to a page fault wakes the faulting |
321 | * task unless DONTWAKE is set. |
322 | */ |
323 | #define UFFDIO_WRITEPROTECT_MODE_WP ((__u64)1<<0) |
324 | #define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1) |
325 | __u64 mode; |
326 | }; |
327 | |
328 | struct uffdio_continue { |
329 | struct uffdio_range range; |
330 | #define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0) |
331 | /* |
332 | * UFFDIO_CONTINUE_MODE_WP will map the page write protected on |
333 | * the fly. UFFDIO_CONTINUE_MODE_WP is available only if the |
334 | * write protected ioctl is implemented for the range |
335 | * according to the uffdio_register.ioctls. |
336 | */ |
337 | #define UFFDIO_CONTINUE_MODE_WP ((__u64)1<<1) |
338 | __u64 mode; |
339 | |
340 | /* |
341 | * Fields below here are written by the ioctl and must be at the end: |
342 | * the copy_from_user will not read past here. |
343 | */ |
344 | __s64 mapped; |
345 | }; |
346 | |
347 | struct uffdio_poison { |
348 | struct uffdio_range range; |
349 | #define UFFDIO_POISON_MODE_DONTWAKE ((__u64)1<<0) |
350 | __u64 mode; |
351 | |
352 | /* |
353 | * Fields below here are written by the ioctl and must be at the end: |
354 | * the copy_from_user will not read past here. |
355 | */ |
356 | __s64 updated; |
357 | }; |
358 | |
359 | struct uffdio_move { |
360 | __u64 dst; |
361 | __u64 src; |
362 | __u64 len; |
363 | /* |
364 | * Especially if used to atomically remove memory from the |
365 | * address space the wake on the dst range is not needed. |
366 | */ |
367 | #define UFFDIO_MOVE_MODE_DONTWAKE ((__u64)1<<0) |
368 | #define UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES ((__u64)1<<1) |
369 | __u64 mode; |
370 | /* |
371 | * "move" is written by the ioctl and must be at the end: the |
372 | * copy_from_user will not read the last 8 bytes. |
373 | */ |
374 | __s64 move; |
375 | }; |
376 | |
377 | /* |
378 | * Flags for the userfaultfd(2) system call itself. |
379 | */ |
380 | |
381 | /* |
382 | * Create a userfaultfd that can handle page faults only in user mode. |
383 | */ |
384 | #define UFFD_USER_MODE_ONLY 1 |
385 | |
386 | #endif /* _LINUX_USERFAULTFD_H */ |
387 | |