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1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */2/*3 * include/linux/userfaultfd.h4 *5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>6 * Copyright (C) 2015 Red Hat, Inc.7 *8 */9 10#ifndef _LINUX_USERFAULTFD_H11#define _LINUX_USERFAULTFD_H12 13#include <linux/types.h>14 15/* ioctls for /dev/userfaultfd */16#define USERFAULTFD_IOC 0xAA17#define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00)18 19/*20 * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and21 * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In22 * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ23 * 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 to67 * 0x3F. UFFDIO_API is the fixed number, everything else can be68 * changed by implementing a different UFFD_API. If sticking to the69 * same UFFD_API more ioctl can be added and userland will be aware of70 * which ioctl the running kernel implements through the ioctl command71 * 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 0xAA86#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 */108struct 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 0x12152#define UFFD_EVENT_FORK 0x13153#define UFFD_EVENT_REMAP 0x14154#define UFFD_EVENT_REMOVE 0x15155#define UFFD_EVENT_UNMAP 0x16156 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 162struct 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 for167 * the API, this notifies userland of which events and/or168 * which flags for each event are enabled in the current169 * kernel.170 *171 * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE172 * are to be considered implicitly always enabled in all kernels as173 * long as the uffdio_api.api requested matches UFFD_API.174 *175 * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER176 * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on177 * hugetlbfs virtual memory ranges. Adding or not adding178 * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has179 * no real functional effect after UFFDIO_API returns, but180 * it's only useful for an initial feature set probe at181 * UFFDIO_API time. There are two ways to use it:182 *183 * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the184 * uffdio_api.features before calling UFFDIO_API, an error185 * will be returned by UFFDIO_API on a kernel without186 * hugetlbfs missing support187 *188 * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in189 * uffdio_api.features and instead it will be set by the190 * kernel in the uffdio_api.features if the kernel supports191 * it, so userland can later check if the feature flag is192 * present in uffdio_api.features after UFFDIO_API193 * succeeded.194 *195 * UFFD_FEATURE_MISSING_SHMEM works the same as196 * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem197 * (i.e. tmpfs and other shmem based APIs).198 *199 * UFFD_FEATURE_SIGBUS feature means no page-fault200 * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead201 * a SIGBUS signal will be sent to the faulting process.202 *203 * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will204 * be returned, if feature is not requested 0 will be returned.205 *206 * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults207 * can be intercepted (via REGISTER_MODE_MINOR) for208 * hugetlbfs-backed pages.209 *210 * UFFD_FEATURE_MINOR_SHMEM indicates the same support as211 * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.212 *213 * UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page214 * faults would be provided and the offset within the page would not be215 * masked.216 *217 * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd218 * write-protection mode is supported on both shmem and hugetlbfs.219 *220 * UFFD_FEATURE_WP_UNPOPULATED indicates that userfaultfd221 * write-protection mode will always apply to unpopulated pages222 * (i.e. empty ptes). This will be the default behavior for shmem223 * & hugetlbfs, so this flag only affects anonymous memory behavior224 * when userfault write-protection mode is registered.225 *226 * UFFD_FEATURE_WP_ASYNC indicates that userfaultfd write-protection227 * asynchronous mode is supported in which the write fault is228 * 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 an232 * 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 256struct uffdio_range {257 __u64 start;258 __u64 len;259};260 261struct 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 the270 * range, keep at the end as the last 8 bytes aren't read.271 */272 __u64 ioctls;273};274 275struct 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 on282 * the fly. UFFDIO_COPY_MODE_WP is available only if the283 * write protected ioctl is implemented for the range284 * 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: the291 * copy_from_user will not read the last 8 bytes.292 */293 __s64 copy;294};295 296struct 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 308struct 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 previously313 * write protected.314 *315 * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up316 * 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 write320 * protection (WP=0) in response to a page fault wakes the faulting321 * 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 328struct 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 on333 * the fly. UFFDIO_CONTINUE_MODE_WP is available only if the334 * write protected ioctl is implemented for the range335 * 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 347struct 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 359struct uffdio_move {360 __u64 dst;361 __u64 src;362 __u64 len;363 /*364 * Especially if used to atomically remove memory from the365 * 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: the372 * 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 1385 386#endif /* _LINUX_USERFAULTFD_H */387