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