1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * include/linux/userfaultfd_k.h 4 * 5 * Copyright (C) 2015 Red Hat, Inc. 6 * 7 */ 8 9#ifndef _LINUX_USERFAULTFD_K_H 10#define _LINUX_USERFAULTFD_K_H 11 12#ifdef CONFIG_USERFAULTFD 13 14#include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */ 15 16#include <linux/fcntl.h> 17#include <linux/mm.h> 18#include <linux/swap.h> 19#include <linux/swapops.h> 20#include <asm-generic/pgtable_uffd.h> 21#include <linux/hugetlb_inline.h> 22 23/* The set of all possible UFFD-related VM flags. */ 24#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR) 25 26/* 27 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining 28 * new flags, since they might collide with O_* ones. We want 29 * to re-use O_* flags that couldn't possibly have a meaning 30 * from userfaultfd, in order to leave a free define-space for 31 * shared O_* flags. 32 */ 33#define UFFD_CLOEXEC O_CLOEXEC 34#define UFFD_NONBLOCK O_NONBLOCK 35 36#define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) 37#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS) 38 39/* 40 * Start with fault_pending_wqh and fault_wqh so they're more likely 41 * to be in the same cacheline. 42 * 43 * Locking order: 44 * fd_wqh.lock 45 * fault_pending_wqh.lock 46 * fault_wqh.lock 47 * event_wqh.lock 48 * 49 * To avoid deadlocks, IRQs must be disabled when taking any of the above locks, 50 * since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's 51 * also taken in IRQ context. 52 */ 53struct userfaultfd_ctx { 54 /* waitqueue head for the pending (i.e. not read) userfaults */ 55 wait_queue_head_t fault_pending_wqh; 56 /* waitqueue head for the userfaults */ 57 wait_queue_head_t fault_wqh; 58 /* waitqueue head for the pseudo fd to wakeup poll/read */ 59 wait_queue_head_t fd_wqh; 60 /* waitqueue head for events */ 61 wait_queue_head_t event_wqh; 62 /* a refile sequence protected by fault_pending_wqh lock */ 63 seqcount_spinlock_t refile_seq; 64 /* pseudo fd refcounting */ 65 refcount_t refcount; 66 /* userfaultfd syscall flags */ 67 unsigned int flags; 68 /* features requested from the userspace */ 69 unsigned int features; 70 /* released */ 71 bool released; 72 /* 73 * Prevents userfaultfd operations (fill/move/wp) from happening while 74 * some non-cooperative event(s) is taking place. Increments are done 75 * in write-mode. Whereas, userfaultfd operations, which includes 76 * reading mmap_changing, is done under read-mode. 77 */ 78 struct rw_semaphore map_changing_lock; 79 /* memory mappings are changing because of non-cooperative event */ 80 atomic_t mmap_changing; 81 /* mm with one ore more vmas attached to this userfaultfd_ctx */ 82 struct mm_struct *mm; 83}; 84 85extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason); 86 87/* A combined operation mode + behavior flags. */ 88typedef unsigned int __bitwise uffd_flags_t; 89 90/* Mutually exclusive modes of operation. */ 91enum mfill_atomic_mode { 92 MFILL_ATOMIC_COPY, 93 MFILL_ATOMIC_ZEROPAGE, 94 MFILL_ATOMIC_CONTINUE, 95 MFILL_ATOMIC_POISON, 96 NR_MFILL_ATOMIC_MODES, 97}; 98 99#define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1) 100#define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr)) 101#define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr)) 102#define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1)) 103 104static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected) 105{ 106 return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected); 107} 108 109static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode) 110{ 111 flags &= ~MFILL_ATOMIC_MODE_MASK; 112 return flags | ((__force uffd_flags_t) mode); 113} 114 115/* Flags controlling behavior. These behavior changes are mode-independent. */ 116#define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0) 117 118extern int mfill_atomic_install_pte(pmd_t *dst_pmd, 119 struct vm_area_struct *dst_vma, 120 unsigned long dst_addr, struct page *page, 121 bool newly_allocated, uffd_flags_t flags); 122 123extern ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start, 124 unsigned long src_start, unsigned long len, 125 uffd_flags_t flags); 126extern ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx, 127 unsigned long dst_start, 128 unsigned long len); 129extern ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long dst_start, 130 unsigned long len, uffd_flags_t flags); 131extern ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start, 132 unsigned long len, uffd_flags_t flags); 133extern int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start, 134 unsigned long len, bool enable_wp); 135extern long uffd_wp_range(struct vm_area_struct *vma, 136 unsigned long start, unsigned long len, bool enable_wp); 137 138/* move_pages */ 139void double_pt_lock(spinlock_t *ptl1, spinlock_t *ptl2); 140void double_pt_unlock(spinlock_t *ptl1, spinlock_t *ptl2); 141ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start, 142 unsigned long src_start, unsigned long len, __u64 flags); 143int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, 144 struct vm_area_struct *dst_vma, 145 struct vm_area_struct *src_vma, 146 unsigned long dst_addr, unsigned long src_addr); 147 148/* mm helpers */ 149static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, 150 struct vm_userfaultfd_ctx vm_ctx) 151{ 152 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx; 153} 154 155/* 156 * Never enable huge pmd sharing on some uffd registered vmas: 157 * 158 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry. 159 * 160 * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for 161 * VMAs which share huge pmds. (If you have two mappings to the same 162 * underlying pages, and fault in the non-UFFD-registered one with a write, 163 * with huge pmd sharing this would *also* setup the second UFFD-registered 164 * mapping, and we'd not get minor faults.) 165 */ 166static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma) 167{ 168 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR); 169} 170 171/* 172 * Don't do fault around for either WP or MINOR registered uffd range. For 173 * MINOR registered range, fault around will be a total disaster and ptes can 174 * be installed without notifications; for WP it should mostly be fine as long 175 * as the fault around checks for pte_none() before the installation, however 176 * to be super safe we just forbid it. 177 */ 178static inline bool uffd_disable_fault_around(struct vm_area_struct *vma) 179{ 180 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR); 181} 182 183static inline bool userfaultfd_missing(struct vm_area_struct *vma) 184{ 185 return vma->vm_flags & VM_UFFD_MISSING; 186} 187 188static inline bool userfaultfd_wp(struct vm_area_struct *vma) 189{ 190 return vma->vm_flags & VM_UFFD_WP; 191} 192 193static inline bool userfaultfd_minor(struct vm_area_struct *vma) 194{ 195 return vma->vm_flags & VM_UFFD_MINOR; 196} 197 198static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, 199 pte_t pte) 200{ 201 return userfaultfd_wp(vma) && pte_uffd_wp(pte); 202} 203 204static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma, 205 pmd_t pmd) 206{ 207 return userfaultfd_wp(vma) && pmd_uffd_wp(pmd); 208} 209 210static inline bool userfaultfd_armed(struct vm_area_struct *vma) 211{ 212 return vma->vm_flags & __VM_UFFD_FLAGS; 213} 214 215static inline bool vma_can_userfault(struct vm_area_struct *vma, 216 unsigned long vm_flags, 217 bool wp_async) 218{ 219 vm_flags &= __VM_UFFD_FLAGS; 220 221 if ((vm_flags & VM_UFFD_MINOR) && 222 (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma))) 223 return false; 224 225 /* 226 * If wp async enabled, and WP is the only mode enabled, allow any 227 * memory type. 228 */ 229 if (wp_async && (vm_flags == VM_UFFD_WP)) 230 return true; 231 232#ifndef CONFIG_PTE_MARKER_UFFD_WP 233 /* 234 * If user requested uffd-wp but not enabled pte markers for 235 * uffd-wp, then shmem & hugetlbfs are not supported but only 236 * anonymous. 237 */ 238 if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma)) 239 return false; 240#endif 241 242 /* By default, allow any of anon|shmem|hugetlb */ 243 return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || 244 vma_is_shmem(vma); 245} 246 247extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *); 248extern void dup_userfaultfd_complete(struct list_head *); 249 250extern void mremap_userfaultfd_prep(struct vm_area_struct *, 251 struct vm_userfaultfd_ctx *); 252extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *, 253 unsigned long from, unsigned long to, 254 unsigned long len); 255 256extern bool userfaultfd_remove(struct vm_area_struct *vma, 257 unsigned long start, 258 unsigned long end); 259 260extern int userfaultfd_unmap_prep(struct vm_area_struct *vma, 261 unsigned long start, unsigned long end, struct list_head *uf); 262extern void userfaultfd_unmap_complete(struct mm_struct *mm, 263 struct list_head *uf); 264extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma); 265extern bool userfaultfd_wp_async(struct vm_area_struct *vma); 266 267#else /* CONFIG_USERFAULTFD */ 268 269/* mm helpers */ 270static inline vm_fault_t handle_userfault(struct vm_fault *vmf, 271 unsigned long reason) 272{ 273 return VM_FAULT_SIGBUS; 274} 275 276static inline long uffd_wp_range(struct vm_area_struct *vma, 277 unsigned long start, unsigned long len, 278 bool enable_wp) 279{ 280 return false; 281} 282 283static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, 284 struct vm_userfaultfd_ctx vm_ctx) 285{ 286 return true; 287} 288 289static inline bool userfaultfd_missing(struct vm_area_struct *vma) 290{ 291 return false; 292} 293 294static inline bool userfaultfd_wp(struct vm_area_struct *vma) 295{ 296 return false; 297} 298 299static inline bool userfaultfd_minor(struct vm_area_struct *vma) 300{ 301 return false; 302} 303 304static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, 305 pte_t pte) 306{ 307 return false; 308} 309 310static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma, 311 pmd_t pmd) 312{ 313 return false; 314} 315 316 317static inline bool userfaultfd_armed(struct vm_area_struct *vma) 318{ 319 return false; 320} 321 322static inline int dup_userfaultfd(struct vm_area_struct *vma, 323 struct list_head *l) 324{ 325 return 0; 326} 327 328static inline void dup_userfaultfd_complete(struct list_head *l) 329{ 330} 331 332static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma, 333 struct vm_userfaultfd_ctx *ctx) 334{ 335} 336 337static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx, 338 unsigned long from, 339 unsigned long to, 340 unsigned long len) 341{ 342} 343 344static inline bool userfaultfd_remove(struct vm_area_struct *vma, 345 unsigned long start, 346 unsigned long end) 347{ 348 return true; 349} 350 351static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma, 352 unsigned long start, unsigned long end, 353 struct list_head *uf) 354{ 355 return 0; 356} 357 358static inline void userfaultfd_unmap_complete(struct mm_struct *mm, 359 struct list_head *uf) 360{ 361} 362 363static inline bool uffd_disable_fault_around(struct vm_area_struct *vma) 364{ 365 return false; 366} 367 368static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma) 369{ 370 return false; 371} 372 373static inline bool userfaultfd_wp_async(struct vm_area_struct *vma) 374{ 375 return false; 376} 377 378#endif /* CONFIG_USERFAULTFD */ 379 380static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma) 381{ 382 /* Only wr-protect mode uses pte markers */ 383 if (!userfaultfd_wp(vma)) 384 return false; 385 386 /* File-based uffd-wp always need markers */ 387 if (!vma_is_anonymous(vma)) 388 return true; 389 390 /* 391 * Anonymous uffd-wp only needs the markers if WP_UNPOPULATED 392 * enabled (to apply markers on zero pages). 393 */ 394 return userfaultfd_wp_unpopulated(vma); 395} 396 397static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry) 398{ 399#ifdef CONFIG_PTE_MARKER_UFFD_WP 400 return is_pte_marker_entry(entry) && 401 (pte_marker_get(entry) & PTE_MARKER_UFFD_WP); 402#else 403 return false; 404#endif 405} 406 407static inline bool pte_marker_uffd_wp(pte_t pte) 408{ 409#ifdef CONFIG_PTE_MARKER_UFFD_WP 410 swp_entry_t entry; 411 412 if (!is_swap_pte(pte)) 413 return false; 414 415 entry = pte_to_swp_entry(pte); 416 417 return pte_marker_entry_uffd_wp(entry); 418#else 419 return false; 420#endif 421} 422 423/* 424 * Returns true if this is a swap pte and was uffd-wp wr-protected in either 425 * forms (pte marker or a normal swap pte), false otherwise. 426 */ 427static inline bool pte_swp_uffd_wp_any(pte_t pte) 428{ 429#ifdef CONFIG_PTE_MARKER_UFFD_WP 430 if (!is_swap_pte(pte)) 431 return false; 432 433 if (pte_swp_uffd_wp(pte)) 434 return true; 435 436 if (pte_marker_uffd_wp(pte)) 437 return true; 438#endif 439 return false; 440} 441 442#endif /* _LINUX_USERFAULTFD_K_H */ 443