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 (at) 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 } __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
