| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * mm/mmap.c |
| 4 | * |
| 5 | * Written by obz. |
| 6 | * |
| 7 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
| 8 | */ |
| 9 | |
| 10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 11 | |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/backing-dev.h> |
| 15 | #include <linux/mm.h> |
| 16 | #include <linux/mm_inline.h> |
| 17 | #include <linux/shm.h> |
| 18 | #include <linux/mman.h> |
| 19 | #include <linux/pagemap.h> |
| 20 | #include <linux/swap.h> |
| 21 | #include <linux/syscalls.h> |
| 22 | #include <linux/capability.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/file.h> |
| 25 | #include <linux/fs.h> |
| 26 | #include <linux/personality.h> |
| 27 | #include <linux/security.h> |
| 28 | #include <linux/hugetlb.h> |
| 29 | #include <linux/shmem_fs.h> |
| 30 | #include <linux/profile.h> |
| 31 | #include <linux/export.h> |
| 32 | #include <linux/mount.h> |
| 33 | #include <linux/mempolicy.h> |
| 34 | #include <linux/rmap.h> |
| 35 | #include <linux/mmu_notifier.h> |
| 36 | #include <linux/mmdebug.h> |
| 37 | #include <linux/perf_event.h> |
| 38 | #include <linux/audit.h> |
| 39 | #include <linux/khugepaged.h> |
| 40 | #include <linux/uprobes.h> |
| 41 | #include <linux/notifier.h> |
| 42 | #include <linux/memory.h> |
| 43 | #include <linux/printk.h> |
| 44 | #include <linux/userfaultfd_k.h> |
| 45 | #include <linux/moduleparam.h> |
| 46 | #include <linux/pkeys.h> |
| 47 | #include <linux/oom.h> |
| 48 | #include <linux/sched/mm.h> |
| 49 | #include <linux/ksm.h> |
| 50 | |
| 51 | #include <linux/uaccess.h> |
| 52 | #include <asm/cacheflush.h> |
| 53 | #include <asm/tlb.h> |
| 54 | #include <asm/mmu_context.h> |
| 55 | |
| 56 | #define CREATE_TRACE_POINTS |
| 57 | #include <trace/events/mmap.h> |
| 58 | |
| 59 | #include "internal.h" |
| 60 | |
| 61 | #ifndef arch_mmap_check |
| 62 | #define arch_mmap_check(addr, len, flags) (0) |
| 63 | #endif |
| 64 | |
| 65 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS |
| 66 | const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; |
| 67 | int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX; |
| 68 | int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; |
| 69 | #endif |
| 70 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 71 | const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; |
| 72 | const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; |
| 73 | int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; |
| 74 | #endif |
| 75 | |
| 76 | static bool ignore_rlimit_data; |
| 77 | core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); |
| 78 | |
| 79 | static void unmap_region(struct mm_struct *mm, struct ma_state *mas, |
| 80 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
| 81 | struct vm_area_struct *next, unsigned long start, |
| 82 | unsigned long end, unsigned long tree_end, bool mm_wr_locked); |
| 83 | |
| 84 | static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) |
| 85 | { |
| 86 | return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); |
| 87 | } |
| 88 | |
| 89 | /* Update vma->vm_page_prot to reflect vma->vm_flags. */ |
| 90 | void vma_set_page_prot(struct vm_area_struct *vma) |
| 91 | { |
| 92 | unsigned long vm_flags = vma->vm_flags; |
| 93 | pgprot_t vm_page_prot; |
| 94 | |
| 95 | vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); |
| 96 | if (vma_wants_writenotify(vma, vm_page_prot)) { |
| 97 | vm_flags &= ~VM_SHARED; |
| 98 | vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); |
| 99 | } |
| 100 | /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */ |
| 101 | WRITE_ONCE(vma->vm_page_prot, vm_page_prot); |
| 102 | } |
| 103 | |
| 104 | /* |
| 105 | * Requires inode->i_mapping->i_mmap_rwsem |
| 106 | */ |
| 107 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, |
| 108 | struct address_space *mapping) |
| 109 | { |
| 110 | if (vma_is_shared_maywrite(vma)) |
| 111 | mapping_unmap_writable(mapping); |
| 112 | |
| 113 | flush_dcache_mmap_lock(mapping); |
| 114 | vma_interval_tree_remove(vma, &mapping->i_mmap); |
| 115 | flush_dcache_mmap_unlock(mapping); |
| 116 | } |
| 117 | |
| 118 | /* |
| 119 | * Unlink a file-based vm structure from its interval tree, to hide |
| 120 | * vma from rmap and vmtruncate before freeing its page tables. |
| 121 | */ |
| 122 | void unlink_file_vma(struct vm_area_struct *vma) |
| 123 | { |
| 124 | struct file *file = vma->vm_file; |
| 125 | |
| 126 | if (file) { |
| 127 | struct address_space *mapping = file->f_mapping; |
| 128 | i_mmap_lock_write(mapping); |
| 129 | __remove_shared_vm_struct(vma, mapping); |
| 130 | i_mmap_unlock_write(mapping); |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | /* |
| 135 | * Close a vm structure and free it. |
| 136 | */ |
| 137 | static void remove_vma(struct vm_area_struct *vma, bool unreachable) |
| 138 | { |
| 139 | might_sleep(); |
| 140 | if (vma->vm_ops && vma->vm_ops->close) |
| 141 | vma->vm_ops->close(vma); |
| 142 | if (vma->vm_file) |
| 143 | fput(vma->vm_file); |
| 144 | mpol_put(vma_policy(vma)); |
| 145 | if (unreachable) |
| 146 | __vm_area_free(vma); |
| 147 | else |
| 148 | vm_area_free(vma); |
| 149 | } |
| 150 | |
| 151 | static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi, |
| 152 | unsigned long min) |
| 153 | { |
| 154 | return mas_prev(&vmi->mas, min); |
| 155 | } |
| 156 | |
| 157 | /* |
| 158 | * check_brk_limits() - Use platform specific check of range & verify mlock |
| 159 | * limits. |
| 160 | * @addr: The address to check |
| 161 | * @len: The size of increase. |
| 162 | * |
| 163 | * Return: 0 on success. |
| 164 | */ |
| 165 | static int check_brk_limits(unsigned long addr, unsigned long len) |
| 166 | { |
| 167 | unsigned long mapped_addr; |
| 168 | |
| 169 | mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); |
| 170 | if (IS_ERR_VALUE(mapped_addr)) |
| 171 | return mapped_addr; |
| 172 | |
| 173 | return mlock_future_ok(current->mm, current->mm->def_flags, len) |
| 174 | ? 0 : -EAGAIN; |
| 175 | } |
| 176 | static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma, |
| 177 | unsigned long addr, unsigned long request, unsigned long flags); |
| 178 | SYSCALL_DEFINE1(brk, unsigned long, brk) |
| 179 | { |
| 180 | unsigned long newbrk, oldbrk, origbrk; |
| 181 | struct mm_struct *mm = current->mm; |
| 182 | struct vm_area_struct *brkvma, *next = NULL; |
| 183 | unsigned long min_brk; |
| 184 | bool populate = false; |
| 185 | LIST_HEAD(uf); |
| 186 | struct vma_iterator vmi; |
| 187 | |
| 188 | if (mmap_write_lock_killable(mm)) |
| 189 | return -EINTR; |
| 190 | |
| 191 | origbrk = mm->brk; |
| 192 | |
| 193 | #ifdef CONFIG_COMPAT_BRK |
| 194 | /* |
| 195 | * CONFIG_COMPAT_BRK can still be overridden by setting |
| 196 | * randomize_va_space to 2, which will still cause mm->start_brk |
| 197 | * to be arbitrarily shifted |
| 198 | */ |
| 199 | if (current->brk_randomized) |
| 200 | min_brk = mm->start_brk; |
| 201 | else |
| 202 | min_brk = mm->end_data; |
| 203 | #else |
| 204 | min_brk = mm->start_brk; |
| 205 | #endif |
| 206 | if (brk < min_brk) |
| 207 | goto out; |
| 208 | |
| 209 | /* |
| 210 | * Check against rlimit here. If this check is done later after the test |
| 211 | * of oldbrk with newbrk then it can escape the test and let the data |
| 212 | * segment grow beyond its set limit the in case where the limit is |
| 213 | * not page aligned -Ram Gupta |
| 214 | */ |
| 215 | if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, |
| 216 | mm->end_data, mm->start_data)) |
| 217 | goto out; |
| 218 | |
| 219 | newbrk = PAGE_ALIGN(brk); |
| 220 | oldbrk = PAGE_ALIGN(mm->brk); |
| 221 | if (oldbrk == newbrk) { |
| 222 | mm->brk = brk; |
| 223 | goto success; |
| 224 | } |
| 225 | |
| 226 | /* Always allow shrinking brk. */ |
| 227 | if (brk <= mm->brk) { |
| 228 | /* Search one past newbrk */ |
| 229 | vma_iter_init(&vmi, mm, newbrk); |
| 230 | brkvma = vma_find(&vmi, oldbrk); |
| 231 | if (!brkvma || brkvma->vm_start >= oldbrk) |
| 232 | goto out; /* mapping intersects with an existing non-brk vma. */ |
| 233 | /* |
| 234 | * mm->brk must be protected by write mmap_lock. |
| 235 | * do_vma_munmap() will drop the lock on success, so update it |
| 236 | * before calling do_vma_munmap(). |
| 237 | */ |
| 238 | mm->brk = brk; |
| 239 | if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true)) |
| 240 | goto out; |
| 241 | |
| 242 | goto success_unlocked; |
| 243 | } |
| 244 | |
| 245 | if (check_brk_limits(oldbrk, newbrk - oldbrk)) |
| 246 | goto out; |
| 247 | |
| 248 | /* |
| 249 | * Only check if the next VMA is within the stack_guard_gap of the |
| 250 | * expansion area |
| 251 | */ |
| 252 | vma_iter_init(&vmi, mm, oldbrk); |
| 253 | next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap); |
| 254 | if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) |
| 255 | goto out; |
| 256 | |
| 257 | brkvma = vma_prev_limit(&vmi, mm->start_brk); |
| 258 | /* Ok, looks good - let it rip. */ |
| 259 | if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0) |
| 260 | goto out; |
| 261 | |
| 262 | mm->brk = brk; |
| 263 | if (mm->def_flags & VM_LOCKED) |
| 264 | populate = true; |
| 265 | |
| 266 | success: |
| 267 | mmap_write_unlock(mm); |
| 268 | success_unlocked: |
| 269 | userfaultfd_unmap_complete(mm, &uf); |
| 270 | if (populate) |
| 271 | mm_populate(oldbrk, newbrk - oldbrk); |
| 272 | return brk; |
| 273 | |
| 274 | out: |
| 275 | mm->brk = origbrk; |
| 276 | mmap_write_unlock(mm); |
| 277 | return origbrk; |
| 278 | } |
| 279 | |
| 280 | #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) |
| 281 | static void validate_mm(struct mm_struct *mm) |
| 282 | { |
| 283 | int bug = 0; |
| 284 | int i = 0; |
| 285 | struct vm_area_struct *vma; |
| 286 | VMA_ITERATOR(vmi, mm, 0); |
| 287 | |
| 288 | mt_validate(&mm->mm_mt); |
| 289 | for_each_vma(vmi, vma) { |
| 290 | #ifdef CONFIG_DEBUG_VM_RB |
| 291 | struct anon_vma *anon_vma = vma->anon_vma; |
| 292 | struct anon_vma_chain *avc; |
| 293 | #endif |
| 294 | unsigned long vmi_start, vmi_end; |
| 295 | bool warn = 0; |
| 296 | |
| 297 | vmi_start = vma_iter_addr(&vmi); |
| 298 | vmi_end = vma_iter_end(&vmi); |
| 299 | if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm)) |
| 300 | warn = 1; |
| 301 | |
| 302 | if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm)) |
| 303 | warn = 1; |
| 304 | |
| 305 | if (warn) { |
| 306 | pr_emerg("issue in %s\n", current->comm); |
| 307 | dump_stack(); |
| 308 | dump_vma(vma); |
| 309 | pr_emerg("tree range: %px start %lx end %lx\n", vma, |
| 310 | vmi_start, vmi_end - 1); |
| 311 | vma_iter_dump_tree(&vmi); |
| 312 | } |
| 313 | |
| 314 | #ifdef CONFIG_DEBUG_VM_RB |
| 315 | if (anon_vma) { |
| 316 | anon_vma_lock_read(anon_vma); |
| 317 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 318 | anon_vma_interval_tree_verify(avc); |
| 319 | anon_vma_unlock_read(anon_vma); |
| 320 | } |
| 321 | #endif |
| 322 | i++; |
| 323 | } |
| 324 | if (i != mm->map_count) { |
| 325 | pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i); |
| 326 | bug = 1; |
| 327 | } |
| 328 | VM_BUG_ON_MM(bug, mm); |
| 329 | } |
| 330 | |
| 331 | #else /* !CONFIG_DEBUG_VM_MAPLE_TREE */ |
| 332 | #define validate_mm(mm) do { } while (0) |
| 333 | #endif /* CONFIG_DEBUG_VM_MAPLE_TREE */ |
| 334 | |
| 335 | /* |
| 336 | * vma has some anon_vma assigned, and is already inserted on that |
| 337 | * anon_vma's interval trees. |
| 338 | * |
| 339 | * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the |
| 340 | * vma must be removed from the anon_vma's interval trees using |
| 341 | * anon_vma_interval_tree_pre_update_vma(). |
| 342 | * |
| 343 | * After the update, the vma will be reinserted using |
| 344 | * anon_vma_interval_tree_post_update_vma(). |
| 345 | * |
| 346 | * The entire update must be protected by exclusive mmap_lock and by |
| 347 | * the root anon_vma's mutex. |
| 348 | */ |
| 349 | static inline void |
| 350 | anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) |
| 351 | { |
| 352 | struct anon_vma_chain *avc; |
| 353 | |
| 354 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 355 | anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); |
| 356 | } |
| 357 | |
| 358 | static inline void |
| 359 | anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) |
| 360 | { |
| 361 | struct anon_vma_chain *avc; |
| 362 | |
| 363 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 364 | anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); |
| 365 | } |
| 366 | |
| 367 | static unsigned long count_vma_pages_range(struct mm_struct *mm, |
| 368 | unsigned long addr, unsigned long end) |
| 369 | { |
| 370 | VMA_ITERATOR(vmi, mm, addr); |
| 371 | struct vm_area_struct *vma; |
| 372 | unsigned long nr_pages = 0; |
| 373 | |
| 374 | for_each_vma_range(vmi, vma, end) { |
| 375 | unsigned long vm_start = max(addr, vma->vm_start); |
| 376 | unsigned long vm_end = min(end, vma->vm_end); |
| 377 | |
| 378 | nr_pages += PHYS_PFN(vm_end - vm_start); |
| 379 | } |
| 380 | |
| 381 | return nr_pages; |
| 382 | } |
| 383 | |
| 384 | static void __vma_link_file(struct vm_area_struct *vma, |
| 385 | struct address_space *mapping) |
| 386 | { |
| 387 | if (vma_is_shared_maywrite(vma)) |
| 388 | mapping_allow_writable(mapping); |
| 389 | |
| 390 | flush_dcache_mmap_lock(mapping); |
| 391 | vma_interval_tree_insert(vma, &mapping->i_mmap); |
| 392 | flush_dcache_mmap_unlock(mapping); |
| 393 | } |
| 394 | |
| 395 | static void vma_link_file(struct vm_area_struct *vma) |
| 396 | { |
| 397 | struct file *file = vma->vm_file; |
| 398 | struct address_space *mapping; |
| 399 | |
| 400 | if (file) { |
| 401 | mapping = file->f_mapping; |
| 402 | i_mmap_lock_write(mapping); |
| 403 | __vma_link_file(vma, mapping); |
| 404 | i_mmap_unlock_write(mapping); |
| 405 | } |
| 406 | } |
| 407 | |
| 408 | static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) |
| 409 | { |
| 410 | VMA_ITERATOR(vmi, mm, 0); |
| 411 | |
| 412 | vma_iter_config(&vmi, vma->vm_start, vma->vm_end); |
| 413 | if (vma_iter_prealloc(&vmi, vma)) |
| 414 | return -ENOMEM; |
| 415 | |
| 416 | vma_start_write(vma); |
| 417 | vma_iter_store(&vmi, vma); |
| 418 | vma_link_file(vma); |
| 419 | mm->map_count++; |
| 420 | validate_mm(mm); |
| 421 | return 0; |
| 422 | } |
| 423 | |
| 424 | /* |
| 425 | * init_multi_vma_prep() - Initializer for struct vma_prepare |
| 426 | * @vp: The vma_prepare struct |
| 427 | * @vma: The vma that will be altered once locked |
| 428 | * @next: The next vma if it is to be adjusted |
| 429 | * @remove: The first vma to be removed |
| 430 | * @remove2: The second vma to be removed |
| 431 | */ |
| 432 | static inline void init_multi_vma_prep(struct vma_prepare *vp, |
| 433 | struct vm_area_struct *vma, struct vm_area_struct *next, |
| 434 | struct vm_area_struct *remove, struct vm_area_struct *remove2) |
| 435 | { |
| 436 | memset(vp, 0, sizeof(struct vma_prepare)); |
| 437 | vp->vma = vma; |
| 438 | vp->anon_vma = vma->anon_vma; |
| 439 | vp->remove = remove; |
| 440 | vp->remove2 = remove2; |
| 441 | vp->adj_next = next; |
| 442 | if (!vp->anon_vma && next) |
| 443 | vp->anon_vma = next->anon_vma; |
| 444 | |
| 445 | vp->file = vma->vm_file; |
| 446 | if (vp->file) |
| 447 | vp->mapping = vma->vm_file->f_mapping; |
| 448 | |
| 449 | } |
| 450 | |
| 451 | /* |
| 452 | * init_vma_prep() - Initializer wrapper for vma_prepare struct |
| 453 | * @vp: The vma_prepare struct |
| 454 | * @vma: The vma that will be altered once locked |
| 455 | */ |
| 456 | static inline void init_vma_prep(struct vma_prepare *vp, |
| 457 | struct vm_area_struct *vma) |
| 458 | { |
| 459 | init_multi_vma_prep(vp, vma, NULL, NULL, NULL); |
| 460 | } |
| 461 | |
| 462 | |
| 463 | /* |
| 464 | * vma_prepare() - Helper function for handling locking VMAs prior to altering |
| 465 | * @vp: The initialized vma_prepare struct |
| 466 | */ |
| 467 | static inline void vma_prepare(struct vma_prepare *vp) |
| 468 | { |
| 469 | if (vp->file) { |
| 470 | uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end); |
| 471 | |
| 472 | if (vp->adj_next) |
| 473 | uprobe_munmap(vp->adj_next, vp->adj_next->vm_start, |
| 474 | vp->adj_next->vm_end); |
| 475 | |
| 476 | i_mmap_lock_write(vp->mapping); |
| 477 | if (vp->insert && vp->insert->vm_file) { |
| 478 | /* |
| 479 | * Put into interval tree now, so instantiated pages |
| 480 | * are visible to arm/parisc __flush_dcache_page |
| 481 | * throughout; but we cannot insert into address |
| 482 | * space until vma start or end is updated. |
| 483 | */ |
| 484 | __vma_link_file(vp->insert, |
| 485 | vp->insert->vm_file->f_mapping); |
| 486 | } |
| 487 | } |
| 488 | |
| 489 | if (vp->anon_vma) { |
| 490 | anon_vma_lock_write(vp->anon_vma); |
| 491 | anon_vma_interval_tree_pre_update_vma(vp->vma); |
| 492 | if (vp->adj_next) |
| 493 | anon_vma_interval_tree_pre_update_vma(vp->adj_next); |
| 494 | } |
| 495 | |
| 496 | if (vp->file) { |
| 497 | flush_dcache_mmap_lock(vp->mapping); |
| 498 | vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap); |
| 499 | if (vp->adj_next) |
| 500 | vma_interval_tree_remove(vp->adj_next, |
| 501 | &vp->mapping->i_mmap); |
| 502 | } |
| 503 | |
| 504 | } |
| 505 | |
| 506 | /* |
| 507 | * vma_complete- Helper function for handling the unlocking after altering VMAs, |
| 508 | * or for inserting a VMA. |
| 509 | * |
| 510 | * @vp: The vma_prepare struct |
| 511 | * @vmi: The vma iterator |
| 512 | * @mm: The mm_struct |
| 513 | */ |
| 514 | static inline void vma_complete(struct vma_prepare *vp, |
| 515 | struct vma_iterator *vmi, struct mm_struct *mm) |
| 516 | { |
| 517 | if (vp->file) { |
| 518 | if (vp->adj_next) |
| 519 | vma_interval_tree_insert(vp->adj_next, |
| 520 | &vp->mapping->i_mmap); |
| 521 | vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap); |
| 522 | flush_dcache_mmap_unlock(vp->mapping); |
| 523 | } |
| 524 | |
| 525 | if (vp->remove && vp->file) { |
| 526 | __remove_shared_vm_struct(vp->remove, vp->mapping); |
| 527 | if (vp->remove2) |
| 528 | __remove_shared_vm_struct(vp->remove2, vp->mapping); |
| 529 | } else if (vp->insert) { |
| 530 | /* |
| 531 | * split_vma has split insert from vma, and needs |
| 532 | * us to insert it before dropping the locks |
| 533 | * (it may either follow vma or precede it). |
| 534 | */ |
| 535 | vma_iter_store(vmi, vp->insert); |
| 536 | mm->map_count++; |
| 537 | } |
| 538 | |
| 539 | if (vp->anon_vma) { |
| 540 | anon_vma_interval_tree_post_update_vma(vp->vma); |
| 541 | if (vp->adj_next) |
| 542 | anon_vma_interval_tree_post_update_vma(vp->adj_next); |
| 543 | anon_vma_unlock_write(vp->anon_vma); |
| 544 | } |
| 545 | |
| 546 | if (vp->file) { |
| 547 | i_mmap_unlock_write(vp->mapping); |
| 548 | uprobe_mmap(vp->vma); |
| 549 | |
| 550 | if (vp->adj_next) |
| 551 | uprobe_mmap(vp->adj_next); |
| 552 | } |
| 553 | |
| 554 | if (vp->remove) { |
| 555 | again: |
| 556 | vma_mark_detached(vp->remove, true); |
| 557 | if (vp->file) { |
| 558 | uprobe_munmap(vp->remove, vp->remove->vm_start, |
| 559 | vp->remove->vm_end); |
| 560 | fput(vp->file); |
| 561 | } |
| 562 | if (vp->remove->anon_vma) |
| 563 | anon_vma_merge(vp->vma, vp->remove); |
| 564 | mm->map_count--; |
| 565 | mpol_put(vma_policy(vp->remove)); |
| 566 | if (!vp->remove2) |
| 567 | WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end); |
| 568 | vm_area_free(vp->remove); |
| 569 | |
| 570 | /* |
| 571 | * In mprotect's case 6 (see comments on vma_merge), |
| 572 | * we are removing both mid and next vmas |
| 573 | */ |
| 574 | if (vp->remove2) { |
| 575 | vp->remove = vp->remove2; |
| 576 | vp->remove2 = NULL; |
| 577 | goto again; |
| 578 | } |
| 579 | } |
| 580 | if (vp->insert && vp->file) |
| 581 | uprobe_mmap(vp->insert); |
| 582 | validate_mm(mm); |
| 583 | } |
| 584 | |
| 585 | /* |
| 586 | * dup_anon_vma() - Helper function to duplicate anon_vma |
| 587 | * @dst: The destination VMA |
| 588 | * @src: The source VMA |
| 589 | * @dup: Pointer to the destination VMA when successful. |
| 590 | * |
| 591 | * Returns: 0 on success. |
| 592 | */ |
| 593 | static inline int dup_anon_vma(struct vm_area_struct *dst, |
| 594 | struct vm_area_struct *src, struct vm_area_struct **dup) |
| 595 | { |
| 596 | /* |
| 597 | * Easily overlooked: when mprotect shifts the boundary, make sure the |
| 598 | * expanding vma has anon_vma set if the shrinking vma had, to cover any |
| 599 | * anon pages imported. |
| 600 | */ |
| 601 | if (src->anon_vma && !dst->anon_vma) { |
| 602 | int ret; |
| 603 | |
| 604 | vma_assert_write_locked(dst); |
| 605 | dst->anon_vma = src->anon_vma; |
| 606 | ret = anon_vma_clone(dst, src); |
| 607 | if (ret) |
| 608 | return ret; |
| 609 | |
| 610 | *dup = dst; |
| 611 | } |
| 612 | |
| 613 | return 0; |
| 614 | } |
| 615 | |
| 616 | /* |
| 617 | * vma_expand - Expand an existing VMA |
| 618 | * |
| 619 | * @vmi: The vma iterator |
| 620 | * @vma: The vma to expand |
| 621 | * @start: The start of the vma |
| 622 | * @end: The exclusive end of the vma |
| 623 | * @pgoff: The page offset of vma |
| 624 | * @next: The current of next vma. |
| 625 | * |
| 626 | * Expand @vma to @start and @end. Can expand off the start and end. Will |
| 627 | * expand over @next if it's different from @vma and @end == @next->vm_end. |
| 628 | * Checking if the @vma can expand and merge with @next needs to be handled by |
| 629 | * the caller. |
| 630 | * |
| 631 | * Returns: 0 on success |
| 632 | */ |
| 633 | int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 634 | unsigned long start, unsigned long end, pgoff_t pgoff, |
| 635 | struct vm_area_struct *next) |
| 636 | { |
| 637 | struct vm_area_struct *anon_dup = NULL; |
| 638 | bool remove_next = false; |
| 639 | struct vma_prepare vp; |
| 640 | |
| 641 | vma_start_write(vma); |
| 642 | if (next && (vma != next) && (end == next->vm_end)) { |
| 643 | int ret; |
| 644 | |
| 645 | remove_next = true; |
| 646 | vma_start_write(next); |
| 647 | ret = dup_anon_vma(vma, next, &anon_dup); |
| 648 | if (ret) |
| 649 | return ret; |
| 650 | } |
| 651 | |
| 652 | init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); |
| 653 | /* Not merging but overwriting any part of next is not handled. */ |
| 654 | VM_WARN_ON(next && !vp.remove && |
| 655 | next != vma && end > next->vm_start); |
| 656 | /* Only handles expanding */ |
| 657 | VM_WARN_ON(vma->vm_start < start || vma->vm_end > end); |
| 658 | |
| 659 | /* Note: vma iterator must be pointing to 'start' */ |
| 660 | vma_iter_config(vmi, start, end); |
| 661 | if (vma_iter_prealloc(vmi, vma)) |
| 662 | goto nomem; |
| 663 | |
| 664 | vma_prepare(&vp); |
| 665 | vma_adjust_trans_huge(vma, start, end, 0); |
| 666 | vma_set_range(vma, start, end, pgoff); |
| 667 | vma_iter_store(vmi, vma); |
| 668 | |
| 669 | vma_complete(&vp, vmi, vma->vm_mm); |
| 670 | return 0; |
| 671 | |
| 672 | nomem: |
| 673 | if (anon_dup) |
| 674 | unlink_anon_vmas(anon_dup); |
| 675 | return -ENOMEM; |
| 676 | } |
| 677 | |
| 678 | /* |
| 679 | * vma_shrink() - Reduce an existing VMAs memory area |
| 680 | * @vmi: The vma iterator |
| 681 | * @vma: The VMA to modify |
| 682 | * @start: The new start |
| 683 | * @end: The new end |
| 684 | * |
| 685 | * Returns: 0 on success, -ENOMEM otherwise |
| 686 | */ |
| 687 | int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 688 | unsigned long start, unsigned long end, pgoff_t pgoff) |
| 689 | { |
| 690 | struct vma_prepare vp; |
| 691 | |
| 692 | WARN_ON((vma->vm_start != start) && (vma->vm_end != end)); |
| 693 | |
| 694 | if (vma->vm_start < start) |
| 695 | vma_iter_config(vmi, vma->vm_start, start); |
| 696 | else |
| 697 | vma_iter_config(vmi, end, vma->vm_end); |
| 698 | |
| 699 | if (vma_iter_prealloc(vmi, NULL)) |
| 700 | return -ENOMEM; |
| 701 | |
| 702 | vma_start_write(vma); |
| 703 | |
| 704 | init_vma_prep(&vp, vma); |
| 705 | vma_prepare(&vp); |
| 706 | vma_adjust_trans_huge(vma, start, end, 0); |
| 707 | |
| 708 | vma_iter_clear(vmi); |
| 709 | vma_set_range(vma, start, end, pgoff); |
| 710 | vma_complete(&vp, vmi, vma->vm_mm); |
| 711 | return 0; |
| 712 | } |
| 713 | |
| 714 | /* |
| 715 | * If the vma has a ->close operation then the driver probably needs to release |
| 716 | * per-vma resources, so we don't attempt to merge those if the caller indicates |
| 717 | * the current vma may be removed as part of the merge. |
| 718 | */ |
| 719 | static inline bool is_mergeable_vma(struct vm_area_struct *vma, |
| 720 | struct file *file, unsigned long vm_flags, |
| 721 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| 722 | struct anon_vma_name *anon_name, bool may_remove_vma) |
| 723 | { |
| 724 | /* |
| 725 | * VM_SOFTDIRTY should not prevent from VMA merging, if we |
| 726 | * match the flags but dirty bit -- the caller should mark |
| 727 | * merged VMA as dirty. If dirty bit won't be excluded from |
| 728 | * comparison, we increase pressure on the memory system forcing |
| 729 | * the kernel to generate new VMAs when old one could be |
| 730 | * extended instead. |
| 731 | */ |
| 732 | if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) |
| 733 | return false; |
| 734 | if (vma->vm_file != file) |
| 735 | return false; |
| 736 | if (may_remove_vma && vma->vm_ops && vma->vm_ops->close) |
| 737 | return false; |
| 738 | if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) |
| 739 | return false; |
| 740 | if (!anon_vma_name_eq(anon_vma_name(vma), anon_name)) |
| 741 | return false; |
| 742 | return true; |
| 743 | } |
| 744 | |
| 745 | static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1, |
| 746 | struct anon_vma *anon_vma2, struct vm_area_struct *vma) |
| 747 | { |
| 748 | /* |
| 749 | * The list_is_singular() test is to avoid merging VMA cloned from |
| 750 | * parents. This can improve scalability caused by anon_vma lock. |
| 751 | */ |
| 752 | if ((!anon_vma1 || !anon_vma2) && (!vma || |
| 753 | list_is_singular(&vma->anon_vma_chain))) |
| 754 | return true; |
| 755 | return anon_vma1 == anon_vma2; |
| 756 | } |
| 757 | |
| 758 | /* |
| 759 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| 760 | * in front of (at a lower virtual address and file offset than) the vma. |
| 761 | * |
| 762 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
| 763 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| 764 | * |
| 765 | * We don't check here for the merged mmap wrapping around the end of pagecache |
| 766 | * indices (16TB on ia32) because do_mmap() does not permit mmap's which |
| 767 | * wrap, nor mmaps which cover the final page at index -1UL. |
| 768 | * |
| 769 | * We assume the vma may be removed as part of the merge. |
| 770 | */ |
| 771 | static bool |
| 772 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, |
| 773 | struct anon_vma *anon_vma, struct file *file, |
| 774 | pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| 775 | struct anon_vma_name *anon_name) |
| 776 | { |
| 777 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) && |
| 778 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| 779 | if (vma->vm_pgoff == vm_pgoff) |
| 780 | return true; |
| 781 | } |
| 782 | return false; |
| 783 | } |
| 784 | |
| 785 | /* |
| 786 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| 787 | * beyond (at a higher virtual address and file offset than) the vma. |
| 788 | * |
| 789 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
| 790 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| 791 | * |
| 792 | * We assume that vma is not removed as part of the merge. |
| 793 | */ |
| 794 | static bool |
| 795 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, |
| 796 | struct anon_vma *anon_vma, struct file *file, |
| 797 | pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| 798 | struct anon_vma_name *anon_name) |
| 799 | { |
| 800 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) && |
| 801 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| 802 | pgoff_t vm_pglen; |
| 803 | vm_pglen = vma_pages(vma); |
| 804 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) |
| 805 | return true; |
| 806 | } |
| 807 | return false; |
| 808 | } |
| 809 | |
| 810 | /* |
| 811 | * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name), |
| 812 | * figure out whether that can be merged with its predecessor or its |
| 813 | * successor. Or both (it neatly fills a hole). |
| 814 | * |
| 815 | * In most cases - when called for mmap, brk or mremap - [addr,end) is |
| 816 | * certain not to be mapped by the time vma_merge is called; but when |
| 817 | * called for mprotect, it is certain to be already mapped (either at |
| 818 | * an offset within prev, or at the start of next), and the flags of |
| 819 | * this area are about to be changed to vm_flags - and the no-change |
| 820 | * case has already been eliminated. |
| 821 | * |
| 822 | * The following mprotect cases have to be considered, where **** is |
| 823 | * the area passed down from mprotect_fixup, never extending beyond one |
| 824 | * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts |
| 825 | * at the same address as **** and is of the same or larger span, and |
| 826 | * NNNN the next vma after ****: |
| 827 | * |
| 828 | * **** **** **** |
| 829 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC |
| 830 | * cannot merge might become might become |
| 831 | * PPNNNNNNNNNN PPPPPPPPPPCC |
| 832 | * mmap, brk or case 4 below case 5 below |
| 833 | * mremap move: |
| 834 | * **** **** |
| 835 | * PPPP NNNN PPPPCCCCNNNN |
| 836 | * might become might become |
| 837 | * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or |
| 838 | * PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or |
| 839 | * PPPPNNNNNNNN 3 PPPPNNNNNNNN 8 |
| 840 | * |
| 841 | * It is important for case 8 that the vma CCCC overlapping the |
| 842 | * region **** is never going to extended over NNNN. Instead NNNN must |
| 843 | * be extended in region **** and CCCC must be removed. This way in |
| 844 | * all cases where vma_merge succeeds, the moment vma_merge drops the |
| 845 | * rmap_locks, the properties of the merged vma will be already |
| 846 | * correct for the whole merged range. Some of those properties like |
| 847 | * vm_page_prot/vm_flags may be accessed by rmap_walks and they must |
| 848 | * be correct for the whole merged range immediately after the |
| 849 | * rmap_locks are released. Otherwise if NNNN would be removed and |
| 850 | * CCCC would be extended over the NNNN range, remove_migration_ptes |
| 851 | * or other rmap walkers (if working on addresses beyond the "end" |
| 852 | * parameter) may establish ptes with the wrong permissions of CCCC |
| 853 | * instead of the right permissions of NNNN. |
| 854 | * |
| 855 | * In the code below: |
| 856 | * PPPP is represented by *prev |
| 857 | * CCCC is represented by *curr or not represented at all (NULL) |
| 858 | * NNNN is represented by *next or not represented at all (NULL) |
| 859 | * **** is not represented - it will be merged and the vma containing the |
| 860 | * area is returned, or the function will return NULL |
| 861 | */ |
| 862 | static struct vm_area_struct |
| 863 | *vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev, |
| 864 | struct vm_area_struct *src, unsigned long addr, unsigned long end, |
| 865 | unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy, |
| 866 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| 867 | struct anon_vma_name *anon_name) |
| 868 | { |
| 869 | struct mm_struct *mm = src->vm_mm; |
| 870 | struct anon_vma *anon_vma = src->anon_vma; |
| 871 | struct file *file = src->vm_file; |
| 872 | struct vm_area_struct *curr, *next, *res; |
| 873 | struct vm_area_struct *vma, *adjust, *remove, *remove2; |
| 874 | struct vm_area_struct *anon_dup = NULL; |
| 875 | struct vma_prepare vp; |
| 876 | pgoff_t vma_pgoff; |
| 877 | int err = 0; |
| 878 | bool merge_prev = false; |
| 879 | bool merge_next = false; |
| 880 | bool vma_expanded = false; |
| 881 | unsigned long vma_start = addr; |
| 882 | unsigned long vma_end = end; |
| 883 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; |
| 884 | long adj_start = 0; |
| 885 | |
| 886 | /* |
| 887 | * We later require that vma->vm_flags == vm_flags, |
| 888 | * so this tests vma->vm_flags & VM_SPECIAL, too. |
| 889 | */ |
| 890 | if (vm_flags & VM_SPECIAL) |
| 891 | return NULL; |
| 892 | |
| 893 | /* Does the input range span an existing VMA? (cases 5 - 8) */ |
| 894 | curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end); |
| 895 | |
| 896 | if (!curr || /* cases 1 - 4 */ |
| 897 | end == curr->vm_end) /* cases 6 - 8, adjacent VMA */ |
| 898 | next = vma_lookup(mm, end); |
| 899 | else |
| 900 | next = NULL; /* case 5 */ |
| 901 | |
| 902 | if (prev) { |
| 903 | vma_start = prev->vm_start; |
| 904 | vma_pgoff = prev->vm_pgoff; |
| 905 | |
| 906 | /* Can we merge the predecessor? */ |
| 907 | if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy) |
| 908 | && can_vma_merge_after(prev, vm_flags, anon_vma, file, |
| 909 | pgoff, vm_userfaultfd_ctx, anon_name)) { |
| 910 | merge_prev = true; |
| 911 | vma_prev(vmi); |
| 912 | } |
| 913 | } |
| 914 | |
| 915 | /* Can we merge the successor? */ |
| 916 | if (next && mpol_equal(policy, vma_policy(next)) && |
| 917 | can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen, |
| 918 | vm_userfaultfd_ctx, anon_name)) { |
| 919 | merge_next = true; |
| 920 | } |
| 921 | |
| 922 | /* Verify some invariant that must be enforced by the caller. */ |
| 923 | VM_WARN_ON(prev && addr <= prev->vm_start); |
| 924 | VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); |
| 925 | VM_WARN_ON(addr >= end); |
| 926 | |
| 927 | if (!merge_prev && !merge_next) |
| 928 | return NULL; /* Not mergeable. */ |
| 929 | |
| 930 | if (merge_prev) |
| 931 | vma_start_write(prev); |
| 932 | |
| 933 | res = vma = prev; |
| 934 | remove = remove2 = adjust = NULL; |
| 935 | |
| 936 | /* Can we merge both the predecessor and the successor? */ |
| 937 | if (merge_prev && merge_next && |
| 938 | is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { |
| 939 | vma_start_write(next); |
| 940 | remove = next; /* case 1 */ |
| 941 | vma_end = next->vm_end; |
| 942 | err = dup_anon_vma(prev, next, &anon_dup); |
| 943 | if (curr) { /* case 6 */ |
| 944 | vma_start_write(curr); |
| 945 | remove = curr; |
| 946 | remove2 = next; |
| 947 | /* |
| 948 | * Note that the dup_anon_vma below cannot overwrite err |
| 949 | * since the first caller would do nothing unless next |
| 950 | * has an anon_vma. |
| 951 | */ |
| 952 | if (!next->anon_vma) |
| 953 | err = dup_anon_vma(prev, curr, &anon_dup); |
| 954 | } |
| 955 | } else if (merge_prev) { /* case 2 */ |
| 956 | if (curr) { |
| 957 | vma_start_write(curr); |
| 958 | if (end == curr->vm_end) { /* case 7 */ |
| 959 | /* |
| 960 | * can_vma_merge_after() assumed we would not be |
| 961 | * removing prev vma, so it skipped the check |
| 962 | * for vm_ops->close, but we are removing curr |
| 963 | */ |
| 964 | if (curr->vm_ops && curr->vm_ops->close) |
| 965 | err = -EINVAL; |
| 966 | remove = curr; |
| 967 | } else { /* case 5 */ |
| 968 | adjust = curr; |
| 969 | adj_start = (end - curr->vm_start); |
| 970 | } |
| 971 | if (!err) |
| 972 | err = dup_anon_vma(prev, curr, &anon_dup); |
| 973 | } |
| 974 | } else { /* merge_next */ |
| 975 | vma_start_write(next); |
| 976 | res = next; |
| 977 | if (prev && addr < prev->vm_end) { /* case 4 */ |
| 978 | vma_start_write(prev); |
| 979 | vma_end = addr; |
| 980 | adjust = next; |
| 981 | adj_start = -(prev->vm_end - addr); |
| 982 | err = dup_anon_vma(next, prev, &anon_dup); |
| 983 | } else { |
| 984 | /* |
| 985 | * Note that cases 3 and 8 are the ONLY ones where prev |
| 986 | * is permitted to be (but is not necessarily) NULL. |
| 987 | */ |
| 988 | vma = next; /* case 3 */ |
| 989 | vma_start = addr; |
| 990 | vma_end = next->vm_end; |
| 991 | vma_pgoff = next->vm_pgoff - pglen; |
| 992 | if (curr) { /* case 8 */ |
| 993 | vma_pgoff = curr->vm_pgoff; |
| 994 | vma_start_write(curr); |
| 995 | remove = curr; |
| 996 | err = dup_anon_vma(next, curr, &anon_dup); |
| 997 | } |
| 998 | } |
| 999 | } |
| 1000 | |
| 1001 | /* Error in anon_vma clone. */ |
| 1002 | if (err) |
| 1003 | goto anon_vma_fail; |
| 1004 | |
| 1005 | if (vma_start < vma->vm_start || vma_end > vma->vm_end) |
| 1006 | vma_expanded = true; |
| 1007 | |
| 1008 | if (vma_expanded) { |
| 1009 | vma_iter_config(vmi, vma_start, vma_end); |
| 1010 | } else { |
| 1011 | vma_iter_config(vmi, adjust->vm_start + adj_start, |
| 1012 | adjust->vm_end); |
| 1013 | } |
| 1014 | |
| 1015 | if (vma_iter_prealloc(vmi, vma)) |
| 1016 | goto prealloc_fail; |
| 1017 | |
| 1018 | init_multi_vma_prep(&vp, vma, adjust, remove, remove2); |
| 1019 | VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && |
| 1020 | vp.anon_vma != adjust->anon_vma); |
| 1021 | |
| 1022 | vma_prepare(&vp); |
| 1023 | vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start); |
| 1024 | vma_set_range(vma, vma_start, vma_end, vma_pgoff); |
| 1025 | |
| 1026 | if (vma_expanded) |
| 1027 | vma_iter_store(vmi, vma); |
| 1028 | |
| 1029 | if (adj_start) { |
| 1030 | adjust->vm_start += adj_start; |
| 1031 | adjust->vm_pgoff += adj_start >> PAGE_SHIFT; |
| 1032 | if (adj_start < 0) { |
| 1033 | WARN_ON(vma_expanded); |
| 1034 | vma_iter_store(vmi, next); |
| 1035 | } |
| 1036 | } |
| 1037 | |
| 1038 | vma_complete(&vp, vmi, mm); |
| 1039 | khugepaged_enter_vma(res, vm_flags); |
| 1040 | return res; |
| 1041 | |
| 1042 | prealloc_fail: |
| 1043 | if (anon_dup) |
| 1044 | unlink_anon_vmas(anon_dup); |
| 1045 | |
| 1046 | anon_vma_fail: |
| 1047 | vma_iter_set(vmi, addr); |
| 1048 | vma_iter_load(vmi); |
| 1049 | return NULL; |
| 1050 | } |
| 1051 | |
| 1052 | /* |
| 1053 | * Rough compatibility check to quickly see if it's even worth looking |
| 1054 | * at sharing an anon_vma. |
| 1055 | * |
| 1056 | * They need to have the same vm_file, and the flags can only differ |
| 1057 | * in things that mprotect may change. |
| 1058 | * |
| 1059 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that |
| 1060 | * we can merge the two vma's. For example, we refuse to merge a vma if |
| 1061 | * there is a vm_ops->close() function, because that indicates that the |
| 1062 | * driver is doing some kind of reference counting. But that doesn't |
| 1063 | * really matter for the anon_vma sharing case. |
| 1064 | */ |
| 1065 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) |
| 1066 | { |
| 1067 | return a->vm_end == b->vm_start && |
| 1068 | mpol_equal(vma_policy(a), vma_policy(b)) && |
| 1069 | a->vm_file == b->vm_file && |
| 1070 | !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) && |
| 1071 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); |
| 1072 | } |
| 1073 | |
| 1074 | /* |
| 1075 | * Do some basic sanity checking to see if we can re-use the anon_vma |
| 1076 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be |
| 1077 | * the same as 'old', the other will be the new one that is trying |
| 1078 | * to share the anon_vma. |
| 1079 | * |
| 1080 | * NOTE! This runs with mmap_lock held for reading, so it is possible that |
| 1081 | * the anon_vma of 'old' is concurrently in the process of being set up |
| 1082 | * by another page fault trying to merge _that_. But that's ok: if it |
| 1083 | * is being set up, that automatically means that it will be a singleton |
| 1084 | * acceptable for merging, so we can do all of this optimistically. But |
| 1085 | * we do that READ_ONCE() to make sure that we never re-load the pointer. |
| 1086 | * |
| 1087 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only |
| 1088 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid |
| 1089 | * is to return an anon_vma that is "complex" due to having gone through |
| 1090 | * a fork). |
| 1091 | * |
| 1092 | * We also make sure that the two vma's are compatible (adjacent, |
| 1093 | * and with the same memory policies). That's all stable, even with just |
| 1094 | * a read lock on the mmap_lock. |
| 1095 | */ |
| 1096 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) |
| 1097 | { |
| 1098 | if (anon_vma_compatible(a, b)) { |
| 1099 | struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); |
| 1100 | |
| 1101 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) |
| 1102 | return anon_vma; |
| 1103 | } |
| 1104 | return NULL; |
| 1105 | } |
| 1106 | |
| 1107 | /* |
| 1108 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check |
| 1109 | * neighbouring vmas for a suitable anon_vma, before it goes off |
| 1110 | * to allocate a new anon_vma. It checks because a repetitive |
| 1111 | * sequence of mprotects and faults may otherwise lead to distinct |
| 1112 | * anon_vmas being allocated, preventing vma merge in subsequent |
| 1113 | * mprotect. |
| 1114 | */ |
| 1115 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) |
| 1116 | { |
| 1117 | struct anon_vma *anon_vma = NULL; |
| 1118 | struct vm_area_struct *prev, *next; |
| 1119 | VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_end); |
| 1120 | |
| 1121 | /* Try next first. */ |
| 1122 | next = vma_iter_load(&vmi); |
| 1123 | if (next) { |
| 1124 | anon_vma = reusable_anon_vma(next, vma, next); |
| 1125 | if (anon_vma) |
| 1126 | return anon_vma; |
| 1127 | } |
| 1128 | |
| 1129 | prev = vma_prev(&vmi); |
| 1130 | VM_BUG_ON_VMA(prev != vma, vma); |
| 1131 | prev = vma_prev(&vmi); |
| 1132 | /* Try prev next. */ |
| 1133 | if (prev) |
| 1134 | anon_vma = reusable_anon_vma(prev, prev, vma); |
| 1135 | |
| 1136 | /* |
| 1137 | * We might reach here with anon_vma == NULL if we can't find |
| 1138 | * any reusable anon_vma. |
| 1139 | * There's no absolute need to look only at touching neighbours: |
| 1140 | * we could search further afield for "compatible" anon_vmas. |
| 1141 | * But it would probably just be a waste of time searching, |
| 1142 | * or lead to too many vmas hanging off the same anon_vma. |
| 1143 | * We're trying to allow mprotect remerging later on, |
| 1144 | * not trying to minimize memory used for anon_vmas. |
| 1145 | */ |
| 1146 | return anon_vma; |
| 1147 | } |
| 1148 | |
| 1149 | /* |
| 1150 | * If a hint addr is less than mmap_min_addr change hint to be as |
| 1151 | * low as possible but still greater than mmap_min_addr |
| 1152 | */ |
| 1153 | static inline unsigned long round_hint_to_min(unsigned long hint) |
| 1154 | { |
| 1155 | hint &= PAGE_MASK; |
| 1156 | if (((void *)hint != NULL) && |
| 1157 | (hint < mmap_min_addr)) |
| 1158 | return PAGE_ALIGN(mmap_min_addr); |
| 1159 | return hint; |
| 1160 | } |
| 1161 | |
| 1162 | bool mlock_future_ok(struct mm_struct *mm, unsigned long flags, |
| 1163 | unsigned long bytes) |
| 1164 | { |
| 1165 | unsigned long locked_pages, limit_pages; |
| 1166 | |
| 1167 | if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK)) |
| 1168 | return true; |
| 1169 | |
| 1170 | locked_pages = bytes >> PAGE_SHIFT; |
| 1171 | locked_pages += mm->locked_vm; |
| 1172 | |
| 1173 | limit_pages = rlimit(RLIMIT_MEMLOCK); |
| 1174 | limit_pages >>= PAGE_SHIFT; |
| 1175 | |
| 1176 | return locked_pages <= limit_pages; |
| 1177 | } |
| 1178 | |
| 1179 | static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) |
| 1180 | { |
| 1181 | if (S_ISREG(inode->i_mode)) |
| 1182 | return MAX_LFS_FILESIZE; |
| 1183 | |
| 1184 | if (S_ISBLK(inode->i_mode)) |
| 1185 | return MAX_LFS_FILESIZE; |
| 1186 | |
| 1187 | if (S_ISSOCK(inode->i_mode)) |
| 1188 | return MAX_LFS_FILESIZE; |
| 1189 | |
| 1190 | /* Special "we do even unsigned file positions" case */ |
| 1191 | if (file->f_mode & FMODE_UNSIGNED_OFFSET) |
| 1192 | return 0; |
| 1193 | |
| 1194 | /* Yes, random drivers might want more. But I'm tired of buggy drivers */ |
| 1195 | return ULONG_MAX; |
| 1196 | } |
| 1197 | |
| 1198 | static inline bool file_mmap_ok(struct file *file, struct inode *inode, |
| 1199 | unsigned long pgoff, unsigned long len) |
| 1200 | { |
| 1201 | u64 maxsize = file_mmap_size_max(file, inode); |
| 1202 | |
| 1203 | if (maxsize && len > maxsize) |
| 1204 | return false; |
| 1205 | maxsize -= len; |
| 1206 | if (pgoff > maxsize >> PAGE_SHIFT) |
| 1207 | return false; |
| 1208 | return true; |
| 1209 | } |
| 1210 | |
| 1211 | /* |
| 1212 | * The caller must write-lock current->mm->mmap_lock. |
| 1213 | */ |
| 1214 | unsigned long do_mmap(struct file *file, unsigned long addr, |
| 1215 | unsigned long len, unsigned long prot, |
| 1216 | unsigned long flags, vm_flags_t vm_flags, |
| 1217 | unsigned long pgoff, unsigned long *populate, |
| 1218 | struct list_head *uf) |
| 1219 | { |
| 1220 | struct mm_struct *mm = current->mm; |
| 1221 | int pkey = 0; |
| 1222 | |
| 1223 | *populate = 0; |
| 1224 | |
| 1225 | if (!len) |
| 1226 | return -EINVAL; |
| 1227 | |
| 1228 | /* |
| 1229 | * Does the application expect PROT_READ to imply PROT_EXEC? |
| 1230 | * |
| 1231 | * (the exception is when the underlying filesystem is noexec |
| 1232 | * mounted, in which case we don't add PROT_EXEC.) |
| 1233 | */ |
| 1234 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
| 1235 | if (!(file && path_noexec(&file->f_path))) |
| 1236 | prot |= PROT_EXEC; |
| 1237 | |
| 1238 | /* force arch specific MAP_FIXED handling in get_unmapped_area */ |
| 1239 | if (flags & MAP_FIXED_NOREPLACE) |
| 1240 | flags |= MAP_FIXED; |
| 1241 | |
| 1242 | if (!(flags & MAP_FIXED)) |
| 1243 | addr = round_hint_to_min(addr); |
| 1244 | |
| 1245 | /* Careful about overflows.. */ |
| 1246 | len = PAGE_ALIGN(len); |
| 1247 | if (!len) |
| 1248 | return -ENOMEM; |
| 1249 | |
| 1250 | /* offset overflow? */ |
| 1251 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) |
| 1252 | return -EOVERFLOW; |
| 1253 | |
| 1254 | /* Too many mappings? */ |
| 1255 | if (mm->map_count > sysctl_max_map_count) |
| 1256 | return -ENOMEM; |
| 1257 | |
| 1258 | /* |
| 1259 | * addr is returned from get_unmapped_area, |
| 1260 | * There are two cases: |
| 1261 | * 1> MAP_FIXED == false |
| 1262 | * unallocated memory, no need to check sealing. |
| 1263 | * 1> MAP_FIXED == true |
| 1264 | * sealing is checked inside mmap_region when |
| 1265 | * do_vmi_munmap is called. |
| 1266 | */ |
| 1267 | |
| 1268 | if (prot == PROT_EXEC) { |
| 1269 | pkey = execute_only_pkey(mm); |
| 1270 | if (pkey < 0) |
| 1271 | pkey = 0; |
| 1272 | } |
| 1273 | |
| 1274 | /* Do simple checking here so the lower-level routines won't have |
| 1275 | * to. we assume access permissions have been handled by the open |
| 1276 | * of the memory object, so we don't do any here. |
| 1277 | */ |
| 1278 | vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | |
| 1279 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
| 1280 | |
| 1281 | /* Obtain the address to map to. we verify (or select) it and ensure |
| 1282 | * that it represents a valid section of the address space. |
| 1283 | */ |
| 1284 | addr = __get_unmapped_area(file, addr, len, pgoff, flags, vm_flags); |
| 1285 | if (IS_ERR_VALUE(addr)) |
| 1286 | return addr; |
| 1287 | |
| 1288 | if (flags & MAP_FIXED_NOREPLACE) { |
| 1289 | if (find_vma_intersection(mm, addr, addr + len)) |
| 1290 | return -EEXIST; |
| 1291 | } |
| 1292 | |
| 1293 | if (flags & MAP_LOCKED) |
| 1294 | if (!can_do_mlock()) |
| 1295 | return -EPERM; |
| 1296 | |
| 1297 | if (!mlock_future_ok(mm, vm_flags, len)) |
| 1298 | return -EAGAIN; |
| 1299 | |
| 1300 | if (file) { |
| 1301 | struct inode *inode = file_inode(file); |
| 1302 | unsigned long flags_mask; |
| 1303 | |
| 1304 | if (!file_mmap_ok(file, inode, pgoff, len)) |
| 1305 | return -EOVERFLOW; |
| 1306 | |
| 1307 | flags_mask = LEGACY_MAP_MASK; |
| 1308 | if (file->f_op->fop_flags & FOP_MMAP_SYNC) |
| 1309 | flags_mask |= MAP_SYNC; |
| 1310 | |
| 1311 | switch (flags & MAP_TYPE) { |
| 1312 | case MAP_SHARED: |
| 1313 | /* |
| 1314 | * Force use of MAP_SHARED_VALIDATE with non-legacy |
| 1315 | * flags. E.g. MAP_SYNC is dangerous to use with |
| 1316 | * MAP_SHARED as you don't know which consistency model |
| 1317 | * you will get. We silently ignore unsupported flags |
| 1318 | * with MAP_SHARED to preserve backward compatibility. |
| 1319 | */ |
| 1320 | flags &= LEGACY_MAP_MASK; |
| 1321 | fallthrough; |
| 1322 | case MAP_SHARED_VALIDATE: |
| 1323 | if (flags & ~flags_mask) |
| 1324 | return -EOPNOTSUPP; |
| 1325 | if (prot & PROT_WRITE) { |
| 1326 | if (!(file->f_mode & FMODE_WRITE)) |
| 1327 | return -EACCES; |
| 1328 | if (IS_SWAPFILE(file->f_mapping->host)) |
| 1329 | return -ETXTBSY; |
| 1330 | } |
| 1331 | |
| 1332 | /* |
| 1333 | * Make sure we don't allow writing to an append-only |
| 1334 | * file.. |
| 1335 | */ |
| 1336 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) |
| 1337 | return -EACCES; |
| 1338 | |
| 1339 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
| 1340 | if (!(file->f_mode & FMODE_WRITE)) |
| 1341 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); |
| 1342 | fallthrough; |
| 1343 | case MAP_PRIVATE: |
| 1344 | if (!(file->f_mode & FMODE_READ)) |
| 1345 | return -EACCES; |
| 1346 | if (path_noexec(&file->f_path)) { |
| 1347 | if (vm_flags & VM_EXEC) |
| 1348 | return -EPERM; |
| 1349 | vm_flags &= ~VM_MAYEXEC; |
| 1350 | } |
| 1351 | |
| 1352 | if (!file->f_op->mmap) |
| 1353 | return -ENODEV; |
| 1354 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| 1355 | return -EINVAL; |
| 1356 | break; |
| 1357 | |
| 1358 | default: |
| 1359 | return -EINVAL; |
| 1360 | } |
| 1361 | } else { |
| 1362 | switch (flags & MAP_TYPE) { |
| 1363 | case MAP_SHARED: |
| 1364 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| 1365 | return -EINVAL; |
| 1366 | /* |
| 1367 | * Ignore pgoff. |
| 1368 | */ |
| 1369 | pgoff = 0; |
| 1370 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
| 1371 | break; |
| 1372 | case MAP_PRIVATE: |
| 1373 | /* |
| 1374 | * Set pgoff according to addr for anon_vma. |
| 1375 | */ |
| 1376 | pgoff = addr >> PAGE_SHIFT; |
| 1377 | break; |
| 1378 | default: |
| 1379 | return -EINVAL; |
| 1380 | } |
| 1381 | } |
| 1382 | |
| 1383 | /* |
| 1384 | * Set 'VM_NORESERVE' if we should not account for the |
| 1385 | * memory use of this mapping. |
| 1386 | */ |
| 1387 | if (flags & MAP_NORESERVE) { |
| 1388 | /* We honor MAP_NORESERVE if allowed to overcommit */ |
| 1389 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) |
| 1390 | vm_flags |= VM_NORESERVE; |
| 1391 | |
| 1392 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ |
| 1393 | if (file && is_file_hugepages(file)) |
| 1394 | vm_flags |= VM_NORESERVE; |
| 1395 | } |
| 1396 | |
| 1397 | addr = mmap_region(file, addr, len, vm_flags, pgoff, uf); |
| 1398 | if (!IS_ERR_VALUE(addr) && |
| 1399 | ((vm_flags & VM_LOCKED) || |
| 1400 | (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) |
| 1401 | *populate = len; |
| 1402 | return addr; |
| 1403 | } |
| 1404 | |
| 1405 | unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, |
| 1406 | unsigned long prot, unsigned long flags, |
| 1407 | unsigned long fd, unsigned long pgoff) |
| 1408 | { |
| 1409 | struct file *file = NULL; |
| 1410 | unsigned long retval; |
| 1411 | |
| 1412 | if (!(flags & MAP_ANONYMOUS)) { |
| 1413 | audit_mmap_fd(fd, flags); |
| 1414 | file = fget(fd); |
| 1415 | if (!file) |
| 1416 | return -EBADF; |
| 1417 | if (is_file_hugepages(file)) { |
| 1418 | len = ALIGN(len, huge_page_size(hstate_file(file))); |
| 1419 | } else if (unlikely(flags & MAP_HUGETLB)) { |
| 1420 | retval = -EINVAL; |
| 1421 | goto out_fput; |
| 1422 | } |
| 1423 | } else if (flags & MAP_HUGETLB) { |
| 1424 | struct hstate *hs; |
| 1425 | |
| 1426 | hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| 1427 | if (!hs) |
| 1428 | return -EINVAL; |
| 1429 | |
| 1430 | len = ALIGN(len, huge_page_size(hs)); |
| 1431 | /* |
| 1432 | * VM_NORESERVE is used because the reservations will be |
| 1433 | * taken when vm_ops->mmap() is called |
| 1434 | */ |
| 1435 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, |
| 1436 | VM_NORESERVE, |
| 1437 | HUGETLB_ANONHUGE_INODE, |
| 1438 | (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| 1439 | if (IS_ERR(file)) |
| 1440 | return PTR_ERR(file); |
| 1441 | } |
| 1442 | |
| 1443 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
| 1444 | out_fput: |
| 1445 | if (file) |
| 1446 | fput(file); |
| 1447 | return retval; |
| 1448 | } |
| 1449 | |
| 1450 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
| 1451 | unsigned long, prot, unsigned long, flags, |
| 1452 | unsigned long, fd, unsigned long, pgoff) |
| 1453 | { |
| 1454 | return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); |
| 1455 | } |
| 1456 | |
| 1457 | #ifdef __ARCH_WANT_SYS_OLD_MMAP |
| 1458 | struct mmap_arg_struct { |
| 1459 | unsigned long addr; |
| 1460 | unsigned long len; |
| 1461 | unsigned long prot; |
| 1462 | unsigned long flags; |
| 1463 | unsigned long fd; |
| 1464 | unsigned long offset; |
| 1465 | }; |
| 1466 | |
| 1467 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
| 1468 | { |
| 1469 | struct mmap_arg_struct a; |
| 1470 | |
| 1471 | if (copy_from_user(&a, arg, sizeof(a))) |
| 1472 | return -EFAULT; |
| 1473 | if (offset_in_page(a.offset)) |
| 1474 | return -EINVAL; |
| 1475 | |
| 1476 | return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
| 1477 | a.offset >> PAGE_SHIFT); |
| 1478 | } |
| 1479 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
| 1480 | |
| 1481 | static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops) |
| 1482 | { |
| 1483 | return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite); |
| 1484 | } |
| 1485 | |
| 1486 | static bool vma_is_shared_writable(struct vm_area_struct *vma) |
| 1487 | { |
| 1488 | return (vma->vm_flags & (VM_WRITE | VM_SHARED)) == |
| 1489 | (VM_WRITE | VM_SHARED); |
| 1490 | } |
| 1491 | |
| 1492 | static bool vma_fs_can_writeback(struct vm_area_struct *vma) |
| 1493 | { |
| 1494 | /* No managed pages to writeback. */ |
| 1495 | if (vma->vm_flags & VM_PFNMAP) |
| 1496 | return false; |
| 1497 | |
| 1498 | return vma->vm_file && vma->vm_file->f_mapping && |
| 1499 | mapping_can_writeback(vma->vm_file->f_mapping); |
| 1500 | } |
| 1501 | |
| 1502 | /* |
| 1503 | * Does this VMA require the underlying folios to have their dirty state |
| 1504 | * tracked? |
| 1505 | */ |
| 1506 | bool vma_needs_dirty_tracking(struct vm_area_struct *vma) |
| 1507 | { |
| 1508 | /* Only shared, writable VMAs require dirty tracking. */ |
| 1509 | if (!vma_is_shared_writable(vma)) |
| 1510 | return false; |
| 1511 | |
| 1512 | /* Does the filesystem need to be notified? */ |
| 1513 | if (vm_ops_needs_writenotify(vma->vm_ops)) |
| 1514 | return true; |
| 1515 | |
| 1516 | /* |
| 1517 | * Even if the filesystem doesn't indicate a need for writenotify, if it |
| 1518 | * can writeback, dirty tracking is still required. |
| 1519 | */ |
| 1520 | return vma_fs_can_writeback(vma); |
| 1521 | } |
| 1522 | |
| 1523 | /* |
| 1524 | * Some shared mappings will want the pages marked read-only |
| 1525 | * to track write events. If so, we'll downgrade vm_page_prot |
| 1526 | * to the private version (using protection_map[] without the |
| 1527 | * VM_SHARED bit). |
| 1528 | */ |
| 1529 | bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) |
| 1530 | { |
| 1531 | /* If it was private or non-writable, the write bit is already clear */ |
| 1532 | if (!vma_is_shared_writable(vma)) |
| 1533 | return false; |
| 1534 | |
| 1535 | /* The backer wishes to know when pages are first written to? */ |
| 1536 | if (vm_ops_needs_writenotify(vma->vm_ops)) |
| 1537 | return true; |
| 1538 | |
| 1539 | /* The open routine did something to the protections that pgprot_modify |
| 1540 | * won't preserve? */ |
| 1541 | if (pgprot_val(vm_page_prot) != |
| 1542 | pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags))) |
| 1543 | return false; |
| 1544 | |
| 1545 | /* |
| 1546 | * Do we need to track softdirty? hugetlb does not support softdirty |
| 1547 | * tracking yet. |
| 1548 | */ |
| 1549 | if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma)) |
| 1550 | return true; |
| 1551 | |
| 1552 | /* Do we need write faults for uffd-wp tracking? */ |
| 1553 | if (userfaultfd_wp(vma)) |
| 1554 | return true; |
| 1555 | |
| 1556 | /* Can the mapping track the dirty pages? */ |
| 1557 | return vma_fs_can_writeback(vma); |
| 1558 | } |
| 1559 | |
| 1560 | /* |
| 1561 | * We account for memory if it's a private writeable mapping, |
| 1562 | * not hugepages and VM_NORESERVE wasn't set. |
| 1563 | */ |
| 1564 | static inline bool accountable_mapping(struct file *file, vm_flags_t vm_flags) |
| 1565 | { |
| 1566 | /* |
| 1567 | * hugetlb has its own accounting separate from the core VM |
| 1568 | * VM_HUGETLB may not be set yet so we cannot check for that flag. |
| 1569 | */ |
| 1570 | if (file && is_file_hugepages(file)) |
| 1571 | return false; |
| 1572 | |
| 1573 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; |
| 1574 | } |
| 1575 | |
| 1576 | /** |
| 1577 | * unmapped_area() - Find an area between the low_limit and the high_limit with |
| 1578 | * the correct alignment and offset, all from @info. Note: current->mm is used |
| 1579 | * for the search. |
| 1580 | * |
| 1581 | * @info: The unmapped area information including the range [low_limit - |
| 1582 | * high_limit), the alignment offset and mask. |
| 1583 | * |
| 1584 | * Return: A memory address or -ENOMEM. |
| 1585 | */ |
| 1586 | static unsigned long unmapped_area(struct vm_unmapped_area_info *info) |
| 1587 | { |
| 1588 | unsigned long length, gap; |
| 1589 | unsigned long low_limit, high_limit; |
| 1590 | struct vm_area_struct *tmp; |
| 1591 | VMA_ITERATOR(vmi, current->mm, 0); |
| 1592 | |
| 1593 | /* Adjust search length to account for worst case alignment overhead */ |
| 1594 | length = info->length + info->align_mask + info->start_gap; |
| 1595 | if (length < info->length) |
| 1596 | return -ENOMEM; |
| 1597 | |
| 1598 | low_limit = info->low_limit; |
| 1599 | if (low_limit < mmap_min_addr) |
| 1600 | low_limit = mmap_min_addr; |
| 1601 | high_limit = info->high_limit; |
| 1602 | retry: |
| 1603 | if (vma_iter_area_lowest(&vmi, low_limit, high_limit, length)) |
| 1604 | return -ENOMEM; |
| 1605 | |
| 1606 | /* |
| 1607 | * Adjust for the gap first so it doesn't interfere with the |
| 1608 | * later alignment. The first step is the minimum needed to |
| 1609 | * fulill the start gap, the next steps is the minimum to align |
| 1610 | * that. It is the minimum needed to fulill both. |
| 1611 | */ |
| 1612 | gap = vma_iter_addr(&vmi) + info->start_gap; |
| 1613 | gap += (info->align_offset - gap) & info->align_mask; |
| 1614 | tmp = vma_next(&vmi); |
| 1615 | if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ |
| 1616 | if (vm_start_gap(tmp) < gap + length - 1) { |
| 1617 | low_limit = tmp->vm_end; |
| 1618 | vma_iter_reset(&vmi); |
| 1619 | goto retry; |
| 1620 | } |
| 1621 | } else { |
| 1622 | tmp = vma_prev(&vmi); |
| 1623 | if (tmp && vm_end_gap(tmp) > gap) { |
| 1624 | low_limit = vm_end_gap(tmp); |
| 1625 | vma_iter_reset(&vmi); |
| 1626 | goto retry; |
| 1627 | } |
| 1628 | } |
| 1629 | |
| 1630 | return gap; |
| 1631 | } |
| 1632 | |
| 1633 | /** |
| 1634 | * unmapped_area_topdown() - Find an area between the low_limit and the |
| 1635 | * high_limit with the correct alignment and offset at the highest available |
| 1636 | * address, all from @info. Note: current->mm is used for the search. |
| 1637 | * |
| 1638 | * @info: The unmapped area information including the range [low_limit - |
| 1639 | * high_limit), the alignment offset and mask. |
| 1640 | * |
| 1641 | * Return: A memory address or -ENOMEM. |
| 1642 | */ |
| 1643 | static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) |
| 1644 | { |
| 1645 | unsigned long length, gap, gap_end; |
| 1646 | unsigned long low_limit, high_limit; |
| 1647 | struct vm_area_struct *tmp; |
| 1648 | VMA_ITERATOR(vmi, current->mm, 0); |
| 1649 | |
| 1650 | /* Adjust search length to account for worst case alignment overhead */ |
| 1651 | length = info->length + info->align_mask + info->start_gap; |
| 1652 | if (length < info->length) |
| 1653 | return -ENOMEM; |
| 1654 | |
| 1655 | low_limit = info->low_limit; |
| 1656 | if (low_limit < mmap_min_addr) |
| 1657 | low_limit = mmap_min_addr; |
| 1658 | high_limit = info->high_limit; |
| 1659 | retry: |
| 1660 | if (vma_iter_area_highest(&vmi, low_limit, high_limit, length)) |
| 1661 | return -ENOMEM; |
| 1662 | |
| 1663 | gap = vma_iter_end(&vmi) - info->length; |
| 1664 | gap -= (gap - info->align_offset) & info->align_mask; |
| 1665 | gap_end = vma_iter_end(&vmi); |
| 1666 | tmp = vma_next(&vmi); |
| 1667 | if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ |
| 1668 | if (vm_start_gap(tmp) < gap_end) { |
| 1669 | high_limit = vm_start_gap(tmp); |
| 1670 | vma_iter_reset(&vmi); |
| 1671 | goto retry; |
| 1672 | } |
| 1673 | } else { |
| 1674 | tmp = vma_prev(&vmi); |
| 1675 | if (tmp && vm_end_gap(tmp) > gap) { |
| 1676 | high_limit = tmp->vm_start; |
| 1677 | vma_iter_reset(&vmi); |
| 1678 | goto retry; |
| 1679 | } |
| 1680 | } |
| 1681 | |
| 1682 | return gap; |
| 1683 | } |
| 1684 | |
| 1685 | /* |
| 1686 | * Search for an unmapped address range. |
| 1687 | * |
| 1688 | * We are looking for a range that: |
| 1689 | * - does not intersect with any VMA; |
| 1690 | * - is contained within the [low_limit, high_limit) interval; |
| 1691 | * - is at least the desired size. |
| 1692 | * - satisfies (begin_addr & align_mask) == (align_offset & align_mask) |
| 1693 | */ |
| 1694 | unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) |
| 1695 | { |
| 1696 | unsigned long addr; |
| 1697 | |
| 1698 | if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) |
| 1699 | addr = unmapped_area_topdown(info); |
| 1700 | else |
| 1701 | addr = unmapped_area(info); |
| 1702 | |
| 1703 | trace_vm_unmapped_area(addr, info); |
| 1704 | return addr; |
| 1705 | } |
| 1706 | |
| 1707 | /* Get an address range which is currently unmapped. |
| 1708 | * For shmat() with addr=0. |
| 1709 | * |
| 1710 | * Ugly calling convention alert: |
| 1711 | * Return value with the low bits set means error value, |
| 1712 | * ie |
| 1713 | * if (ret & ~PAGE_MASK) |
| 1714 | * error = ret; |
| 1715 | * |
| 1716 | * This function "knows" that -ENOMEM has the bits set. |
| 1717 | */ |
| 1718 | unsigned long |
| 1719 | generic_get_unmapped_area(struct file *filp, unsigned long addr, |
| 1720 | unsigned long len, unsigned long pgoff, |
| 1721 | unsigned long flags) |
| 1722 | { |
| 1723 | struct mm_struct *mm = current->mm; |
| 1724 | struct vm_area_struct *vma, *prev; |
| 1725 | struct vm_unmapped_area_info info = {}; |
| 1726 | const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); |
| 1727 | |
| 1728 | if (len > mmap_end - mmap_min_addr) |
| 1729 | return -ENOMEM; |
| 1730 | |
| 1731 | if (flags & MAP_FIXED) |
| 1732 | return addr; |
| 1733 | |
| 1734 | if (addr) { |
| 1735 | addr = PAGE_ALIGN(addr); |
| 1736 | vma = find_vma_prev(mm, addr, &prev); |
| 1737 | if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| 1738 | (!vma || addr + len <= vm_start_gap(vma)) && |
| 1739 | (!prev || addr >= vm_end_gap(prev))) |
| 1740 | return addr; |
| 1741 | } |
| 1742 | |
| 1743 | info.length = len; |
| 1744 | info.low_limit = mm->mmap_base; |
| 1745 | info.high_limit = mmap_end; |
| 1746 | return vm_unmapped_area(&info); |
| 1747 | } |
| 1748 | |
| 1749 | #ifndef HAVE_ARCH_UNMAPPED_AREA |
| 1750 | unsigned long |
| 1751 | arch_get_unmapped_area(struct file *filp, unsigned long addr, |
| 1752 | unsigned long len, unsigned long pgoff, |
| 1753 | unsigned long flags) |
| 1754 | { |
| 1755 | return generic_get_unmapped_area(filp, addr, len, pgoff, flags); |
| 1756 | } |
| 1757 | #endif |
| 1758 | |
| 1759 | /* |
| 1760 | * This mmap-allocator allocates new areas top-down from below the |
| 1761 | * stack's low limit (the base): |
| 1762 | */ |
| 1763 | unsigned long |
| 1764 | generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr, |
| 1765 | unsigned long len, unsigned long pgoff, |
| 1766 | unsigned long flags) |
| 1767 | { |
| 1768 | struct vm_area_struct *vma, *prev; |
| 1769 | struct mm_struct *mm = current->mm; |
| 1770 | struct vm_unmapped_area_info info = {}; |
| 1771 | const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); |
| 1772 | |
| 1773 | /* requested length too big for entire address space */ |
| 1774 | if (len > mmap_end - mmap_min_addr) |
| 1775 | return -ENOMEM; |
| 1776 | |
| 1777 | if (flags & MAP_FIXED) |
| 1778 | return addr; |
| 1779 | |
| 1780 | /* requesting a specific address */ |
| 1781 | if (addr) { |
| 1782 | addr = PAGE_ALIGN(addr); |
| 1783 | vma = find_vma_prev(mm, addr, &prev); |
| 1784 | if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| 1785 | (!vma || addr + len <= vm_start_gap(vma)) && |
| 1786 | (!prev || addr >= vm_end_gap(prev))) |
| 1787 | return addr; |
| 1788 | } |
| 1789 | |
| 1790 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; |
| 1791 | info.length = len; |
| 1792 | info.low_limit = PAGE_SIZE; |
| 1793 | info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); |
| 1794 | addr = vm_unmapped_area(&info); |
| 1795 | |
| 1796 | /* |
| 1797 | * A failed mmap() very likely causes application failure, |
| 1798 | * so fall back to the bottom-up function here. This scenario |
| 1799 | * can happen with large stack limits and large mmap() |
| 1800 | * allocations. |
| 1801 | */ |
| 1802 | if (offset_in_page(addr)) { |
| 1803 | VM_BUG_ON(addr != -ENOMEM); |
| 1804 | info.flags = 0; |
| 1805 | info.low_limit = TASK_UNMAPPED_BASE; |
| 1806 | info.high_limit = mmap_end; |
| 1807 | addr = vm_unmapped_area(&info); |
| 1808 | } |
| 1809 | |
| 1810 | return addr; |
| 1811 | } |
| 1812 | |
| 1813 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN |
| 1814 | unsigned long |
| 1815 | arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, |
| 1816 | unsigned long len, unsigned long pgoff, |
| 1817 | unsigned long flags) |
| 1818 | { |
| 1819 | return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); |
| 1820 | } |
| 1821 | #endif |
| 1822 | |
| 1823 | #ifndef HAVE_ARCH_UNMAPPED_AREA_VMFLAGS |
| 1824 | unsigned long |
| 1825 | arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned long len, |
| 1826 | unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) |
| 1827 | { |
| 1828 | return arch_get_unmapped_area(filp, addr, len, pgoff, flags); |
| 1829 | } |
| 1830 | |
| 1831 | unsigned long |
| 1832 | arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr, |
| 1833 | unsigned long len, unsigned long pgoff, |
| 1834 | unsigned long flags, vm_flags_t vm_flags) |
| 1835 | { |
| 1836 | return arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); |
| 1837 | } |
| 1838 | #endif |
| 1839 | |
| 1840 | unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *filp, |
| 1841 | unsigned long addr, unsigned long len, |
| 1842 | unsigned long pgoff, unsigned long flags, |
| 1843 | vm_flags_t vm_flags) |
| 1844 | { |
| 1845 | if (test_bit(MMF_TOPDOWN, &mm->flags)) |
| 1846 | return arch_get_unmapped_area_topdown_vmflags(filp, addr, len, pgoff, |
| 1847 | flags, vm_flags); |
| 1848 | return arch_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, vm_flags); |
| 1849 | } |
| 1850 | |
| 1851 | unsigned long |
| 1852 | __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, |
| 1853 | unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) |
| 1854 | { |
| 1855 | unsigned long (*get_area)(struct file *, unsigned long, |
| 1856 | unsigned long, unsigned long, unsigned long) |
| 1857 | = NULL; |
| 1858 | |
| 1859 | unsigned long error = arch_mmap_check(addr, len, flags); |
| 1860 | if (error) |
| 1861 | return error; |
| 1862 | |
| 1863 | /* Careful about overflows.. */ |
| 1864 | if (len > TASK_SIZE) |
| 1865 | return -ENOMEM; |
| 1866 | |
| 1867 | if (file) { |
| 1868 | if (file->f_op->get_unmapped_area) |
| 1869 | get_area = file->f_op->get_unmapped_area; |
| 1870 | } else if (flags & MAP_SHARED) { |
| 1871 | /* |
| 1872 | * mmap_region() will call shmem_zero_setup() to create a file, |
| 1873 | * so use shmem's get_unmapped_area in case it can be huge. |
| 1874 | */ |
| 1875 | get_area = shmem_get_unmapped_area; |
| 1876 | } |
| 1877 | |
| 1878 | /* Always treat pgoff as zero for anonymous memory. */ |
| 1879 | if (!file) |
| 1880 | pgoff = 0; |
| 1881 | |
| 1882 | if (get_area) { |
| 1883 | addr = get_area(file, addr, len, pgoff, flags); |
| 1884 | } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { |
| 1885 | /* Ensures that larger anonymous mappings are THP aligned. */ |
| 1886 | addr = thp_get_unmapped_area_vmflags(file, addr, len, |
| 1887 | pgoff, flags, vm_flags); |
| 1888 | } else { |
| 1889 | addr = mm_get_unmapped_area_vmflags(current->mm, file, addr, len, |
| 1890 | pgoff, flags, vm_flags); |
| 1891 | } |
| 1892 | if (IS_ERR_VALUE(addr)) |
| 1893 | return addr; |
| 1894 | |
| 1895 | if (addr > TASK_SIZE - len) |
| 1896 | return -ENOMEM; |
| 1897 | if (offset_in_page(addr)) |
| 1898 | return -EINVAL; |
| 1899 | |
| 1900 | error = security_mmap_addr(addr); |
| 1901 | return error ? error : addr; |
| 1902 | } |
| 1903 | |
| 1904 | unsigned long |
| 1905 | mm_get_unmapped_area(struct mm_struct *mm, struct file *file, |
| 1906 | unsigned long addr, unsigned long len, |
| 1907 | unsigned long pgoff, unsigned long flags) |
| 1908 | { |
| 1909 | if (test_bit(MMF_TOPDOWN, &mm->flags)) |
| 1910 | return arch_get_unmapped_area_topdown(file, addr, len, pgoff, flags); |
| 1911 | return arch_get_unmapped_area(file, addr, len, pgoff, flags); |
| 1912 | } |
| 1913 | EXPORT_SYMBOL(mm_get_unmapped_area); |
| 1914 | |
| 1915 | /** |
| 1916 | * find_vma_intersection() - Look up the first VMA which intersects the interval |
| 1917 | * @mm: The process address space. |
| 1918 | * @start_addr: The inclusive start user address. |
| 1919 | * @end_addr: The exclusive end user address. |
| 1920 | * |
| 1921 | * Returns: The first VMA within the provided range, %NULL otherwise. Assumes |
| 1922 | * start_addr < end_addr. |
| 1923 | */ |
| 1924 | struct vm_area_struct *find_vma_intersection(struct mm_struct *mm, |
| 1925 | unsigned long start_addr, |
| 1926 | unsigned long end_addr) |
| 1927 | { |
| 1928 | unsigned long index = start_addr; |
| 1929 | |
| 1930 | mmap_assert_locked(mm); |
| 1931 | return mt_find(&mm->mm_mt, &index, end_addr - 1); |
| 1932 | } |
| 1933 | EXPORT_SYMBOL(find_vma_intersection); |
| 1934 | |
| 1935 | /** |
| 1936 | * find_vma() - Find the VMA for a given address, or the next VMA. |
| 1937 | * @mm: The mm_struct to check |
| 1938 | * @addr: The address |
| 1939 | * |
| 1940 | * Returns: The VMA associated with addr, or the next VMA. |
| 1941 | * May return %NULL in the case of no VMA at addr or above. |
| 1942 | */ |
| 1943 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
| 1944 | { |
| 1945 | unsigned long index = addr; |
| 1946 | |
| 1947 | mmap_assert_locked(mm); |
| 1948 | return mt_find(&mm->mm_mt, &index, ULONG_MAX); |
| 1949 | } |
| 1950 | EXPORT_SYMBOL(find_vma); |
| 1951 | |
| 1952 | /** |
| 1953 | * find_vma_prev() - Find the VMA for a given address, or the next vma and |
| 1954 | * set %pprev to the previous VMA, if any. |
| 1955 | * @mm: The mm_struct to check |
| 1956 | * @addr: The address |
| 1957 | * @pprev: The pointer to set to the previous VMA |
| 1958 | * |
| 1959 | * Note that RCU lock is missing here since the external mmap_lock() is used |
| 1960 | * instead. |
| 1961 | * |
| 1962 | * Returns: The VMA associated with @addr, or the next vma. |
| 1963 | * May return %NULL in the case of no vma at addr or above. |
| 1964 | */ |
| 1965 | struct vm_area_struct * |
| 1966 | find_vma_prev(struct mm_struct *mm, unsigned long addr, |
| 1967 | struct vm_area_struct **pprev) |
| 1968 | { |
| 1969 | struct vm_area_struct *vma; |
| 1970 | VMA_ITERATOR(vmi, mm, addr); |
| 1971 | |
| 1972 | vma = vma_iter_load(&vmi); |
| 1973 | *pprev = vma_prev(&vmi); |
| 1974 | if (!vma) |
| 1975 | vma = vma_next(&vmi); |
| 1976 | return vma; |
| 1977 | } |
| 1978 | |
| 1979 | /* |
| 1980 | * Verify that the stack growth is acceptable and |
| 1981 | * update accounting. This is shared with both the |
| 1982 | * grow-up and grow-down cases. |
| 1983 | */ |
| 1984 | static int acct_stack_growth(struct vm_area_struct *vma, |
| 1985 | unsigned long size, unsigned long grow) |
| 1986 | { |
| 1987 | struct mm_struct *mm = vma->vm_mm; |
| 1988 | unsigned long new_start; |
| 1989 | |
| 1990 | /* address space limit tests */ |
| 1991 | if (!may_expand_vm(mm, vma->vm_flags, grow)) |
| 1992 | return -ENOMEM; |
| 1993 | |
| 1994 | /* Stack limit test */ |
| 1995 | if (size > rlimit(RLIMIT_STACK)) |
| 1996 | return -ENOMEM; |
| 1997 | |
| 1998 | /* mlock limit tests */ |
| 1999 | if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT)) |
| 2000 | return -ENOMEM; |
| 2001 | |
| 2002 | /* Check to ensure the stack will not grow into a hugetlb-only region */ |
| 2003 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : |
| 2004 | vma->vm_end - size; |
| 2005 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) |
| 2006 | return -EFAULT; |
| 2007 | |
| 2008 | /* |
| 2009 | * Overcommit.. This must be the final test, as it will |
| 2010 | * update security statistics. |
| 2011 | */ |
| 2012 | if (security_vm_enough_memory_mm(mm, grow)) |
| 2013 | return -ENOMEM; |
| 2014 | |
| 2015 | return 0; |
| 2016 | } |
| 2017 | |
| 2018 | #if defined(CONFIG_STACK_GROWSUP) |
| 2019 | /* |
| 2020 | * PA-RISC uses this for its stack. |
| 2021 | * vma is the last one with address > vma->vm_end. Have to extend vma. |
| 2022 | */ |
| 2023 | static int expand_upwards(struct vm_area_struct *vma, unsigned long address) |
| 2024 | { |
| 2025 | struct mm_struct *mm = vma->vm_mm; |
| 2026 | struct vm_area_struct *next; |
| 2027 | unsigned long gap_addr; |
| 2028 | int error = 0; |
| 2029 | VMA_ITERATOR(vmi, mm, vma->vm_start); |
| 2030 | |
| 2031 | if (!(vma->vm_flags & VM_GROWSUP)) |
| 2032 | return -EFAULT; |
| 2033 | |
| 2034 | /* Guard against exceeding limits of the address space. */ |
| 2035 | address &= PAGE_MASK; |
| 2036 | if (address >= (TASK_SIZE & PAGE_MASK)) |
| 2037 | return -ENOMEM; |
| 2038 | address += PAGE_SIZE; |
| 2039 | |
| 2040 | /* Enforce stack_guard_gap */ |
| 2041 | gap_addr = address + stack_guard_gap; |
| 2042 | |
| 2043 | /* Guard against overflow */ |
| 2044 | if (gap_addr < address || gap_addr > TASK_SIZE) |
| 2045 | gap_addr = TASK_SIZE; |
| 2046 | |
| 2047 | next = find_vma_intersection(mm, vma->vm_end, gap_addr); |
| 2048 | if (next && vma_is_accessible(next)) { |
| 2049 | if (!(next->vm_flags & VM_GROWSUP)) |
| 2050 | return -ENOMEM; |
| 2051 | /* Check that both stack segments have the same anon_vma? */ |
| 2052 | } |
| 2053 | |
| 2054 | if (next) |
| 2055 | vma_iter_prev_range_limit(&vmi, address); |
| 2056 | |
| 2057 | vma_iter_config(&vmi, vma->vm_start, address); |
| 2058 | if (vma_iter_prealloc(&vmi, vma)) |
| 2059 | return -ENOMEM; |
| 2060 | |
| 2061 | /* We must make sure the anon_vma is allocated. */ |
| 2062 | if (unlikely(anon_vma_prepare(vma))) { |
| 2063 | vma_iter_free(&vmi); |
| 2064 | return -ENOMEM; |
| 2065 | } |
| 2066 | |
| 2067 | /* Lock the VMA before expanding to prevent concurrent page faults */ |
| 2068 | vma_start_write(vma); |
| 2069 | /* |
| 2070 | * vma->vm_start/vm_end cannot change under us because the caller |
| 2071 | * is required to hold the mmap_lock in read mode. We need the |
| 2072 | * anon_vma lock to serialize against concurrent expand_stacks. |
| 2073 | */ |
| 2074 | anon_vma_lock_write(vma->anon_vma); |
| 2075 | |
| 2076 | /* Somebody else might have raced and expanded it already */ |
| 2077 | if (address > vma->vm_end) { |
| 2078 | unsigned long size, grow; |
| 2079 | |
| 2080 | size = address - vma->vm_start; |
| 2081 | grow = (address - vma->vm_end) >> PAGE_SHIFT; |
| 2082 | |
| 2083 | error = -ENOMEM; |
| 2084 | if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { |
| 2085 | error = acct_stack_growth(vma, size, grow); |
| 2086 | if (!error) { |
| 2087 | /* |
| 2088 | * We only hold a shared mmap_lock lock here, so |
| 2089 | * we need to protect against concurrent vma |
| 2090 | * expansions. anon_vma_lock_write() doesn't |
| 2091 | * help here, as we don't guarantee that all |
| 2092 | * growable vmas in a mm share the same root |
| 2093 | * anon vma. So, we reuse mm->page_table_lock |
| 2094 | * to guard against concurrent vma expansions. |
| 2095 | */ |
| 2096 | spin_lock(&mm->page_table_lock); |
| 2097 | if (vma->vm_flags & VM_LOCKED) |
| 2098 | mm->locked_vm += grow; |
| 2099 | vm_stat_account(mm, vma->vm_flags, grow); |
| 2100 | anon_vma_interval_tree_pre_update_vma(vma); |
| 2101 | vma->vm_end = address; |
| 2102 | /* Overwrite old entry in mtree. */ |
| 2103 | vma_iter_store(&vmi, vma); |
| 2104 | anon_vma_interval_tree_post_update_vma(vma); |
| 2105 | spin_unlock(&mm->page_table_lock); |
| 2106 | |
| 2107 | perf_event_mmap(vma); |
| 2108 | } |
| 2109 | } |
| 2110 | } |
| 2111 | anon_vma_unlock_write(vma->anon_vma); |
| 2112 | vma_iter_free(&vmi); |
| 2113 | validate_mm(mm); |
| 2114 | return error; |
| 2115 | } |
| 2116 | #endif /* CONFIG_STACK_GROWSUP */ |
| 2117 | |
| 2118 | /* |
| 2119 | * vma is the first one with address < vma->vm_start. Have to extend vma. |
| 2120 | * mmap_lock held for writing. |
| 2121 | */ |
| 2122 | int expand_downwards(struct vm_area_struct *vma, unsigned long address) |
| 2123 | { |
| 2124 | struct mm_struct *mm = vma->vm_mm; |
| 2125 | struct vm_area_struct *prev; |
| 2126 | int error = 0; |
| 2127 | VMA_ITERATOR(vmi, mm, vma->vm_start); |
| 2128 | |
| 2129 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 2130 | return -EFAULT; |
| 2131 | |
| 2132 | address &= PAGE_MASK; |
| 2133 | if (address < mmap_min_addr || address < FIRST_USER_ADDRESS) |
| 2134 | return -EPERM; |
| 2135 | |
| 2136 | /* Enforce stack_guard_gap */ |
| 2137 | prev = vma_prev(&vmi); |
| 2138 | /* Check that both stack segments have the same anon_vma? */ |
| 2139 | if (prev) { |
| 2140 | if (!(prev->vm_flags & VM_GROWSDOWN) && |
| 2141 | vma_is_accessible(prev) && |
| 2142 | (address - prev->vm_end < stack_guard_gap)) |
| 2143 | return -ENOMEM; |
| 2144 | } |
| 2145 | |
| 2146 | if (prev) |
| 2147 | vma_iter_next_range_limit(&vmi, vma->vm_start); |
| 2148 | |
| 2149 | vma_iter_config(&vmi, address, vma->vm_end); |
| 2150 | if (vma_iter_prealloc(&vmi, vma)) |
| 2151 | return -ENOMEM; |
| 2152 | |
| 2153 | /* We must make sure the anon_vma is allocated. */ |
| 2154 | if (unlikely(anon_vma_prepare(vma))) { |
| 2155 | vma_iter_free(&vmi); |
| 2156 | return -ENOMEM; |
| 2157 | } |
| 2158 | |
| 2159 | /* Lock the VMA before expanding to prevent concurrent page faults */ |
| 2160 | vma_start_write(vma); |
| 2161 | /* |
| 2162 | * vma->vm_start/vm_end cannot change under us because the caller |
| 2163 | * is required to hold the mmap_lock in read mode. We need the |
| 2164 | * anon_vma lock to serialize against concurrent expand_stacks. |
| 2165 | */ |
| 2166 | anon_vma_lock_write(vma->anon_vma); |
| 2167 | |
| 2168 | /* Somebody else might have raced and expanded it already */ |
| 2169 | if (address < vma->vm_start) { |
| 2170 | unsigned long size, grow; |
| 2171 | |
| 2172 | size = vma->vm_end - address; |
| 2173 | grow = (vma->vm_start - address) >> PAGE_SHIFT; |
| 2174 | |
| 2175 | error = -ENOMEM; |
| 2176 | if (grow <= vma->vm_pgoff) { |
| 2177 | error = acct_stack_growth(vma, size, grow); |
| 2178 | if (!error) { |
| 2179 | /* |
| 2180 | * We only hold a shared mmap_lock lock here, so |
| 2181 | * we need to protect against concurrent vma |
| 2182 | * expansions. anon_vma_lock_write() doesn't |
| 2183 | * help here, as we don't guarantee that all |
| 2184 | * growable vmas in a mm share the same root |
| 2185 | * anon vma. So, we reuse mm->page_table_lock |
| 2186 | * to guard against concurrent vma expansions. |
| 2187 | */ |
| 2188 | spin_lock(&mm->page_table_lock); |
| 2189 | if (vma->vm_flags & VM_LOCKED) |
| 2190 | mm->locked_vm += grow; |
| 2191 | vm_stat_account(mm, vma->vm_flags, grow); |
| 2192 | anon_vma_interval_tree_pre_update_vma(vma); |
| 2193 | vma->vm_start = address; |
| 2194 | vma->vm_pgoff -= grow; |
| 2195 | /* Overwrite old entry in mtree. */ |
| 2196 | vma_iter_store(&vmi, vma); |
| 2197 | anon_vma_interval_tree_post_update_vma(vma); |
| 2198 | spin_unlock(&mm->page_table_lock); |
| 2199 | |
| 2200 | perf_event_mmap(vma); |
| 2201 | } |
| 2202 | } |
| 2203 | } |
| 2204 | anon_vma_unlock_write(vma->anon_vma); |
| 2205 | vma_iter_free(&vmi); |
| 2206 | validate_mm(mm); |
| 2207 | return error; |
| 2208 | } |
| 2209 | |
| 2210 | /* enforced gap between the expanding stack and other mappings. */ |
| 2211 | unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; |
| 2212 | |
| 2213 | static int __init cmdline_parse_stack_guard_gap(char *p) |
| 2214 | { |
| 2215 | unsigned long val; |
| 2216 | char *endptr; |
| 2217 | |
| 2218 | val = simple_strtoul(p, &endptr, 10); |
| 2219 | if (!*endptr) |
| 2220 | stack_guard_gap = val << PAGE_SHIFT; |
| 2221 | |
| 2222 | return 1; |
| 2223 | } |
| 2224 | __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); |
| 2225 | |
| 2226 | #ifdef CONFIG_STACK_GROWSUP |
| 2227 | int expand_stack_locked(struct vm_area_struct *vma, unsigned long address) |
| 2228 | { |
| 2229 | return expand_upwards(vma, address); |
| 2230 | } |
| 2231 | |
| 2232 | struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) |
| 2233 | { |
| 2234 | struct vm_area_struct *vma, *prev; |
| 2235 | |
| 2236 | addr &= PAGE_MASK; |
| 2237 | vma = find_vma_prev(mm, addr, &prev); |
| 2238 | if (vma && (vma->vm_start <= addr)) |
| 2239 | return vma; |
| 2240 | if (!prev) |
| 2241 | return NULL; |
| 2242 | if (expand_stack_locked(prev, addr)) |
| 2243 | return NULL; |
| 2244 | if (prev->vm_flags & VM_LOCKED) |
| 2245 | populate_vma_page_range(prev, addr, prev->vm_end, NULL); |
| 2246 | return prev; |
| 2247 | } |
| 2248 | #else |
| 2249 | int expand_stack_locked(struct vm_area_struct *vma, unsigned long address) |
| 2250 | { |
| 2251 | return expand_downwards(vma, address); |
| 2252 | } |
| 2253 | |
| 2254 | struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) |
| 2255 | { |
| 2256 | struct vm_area_struct *vma; |
| 2257 | unsigned long start; |
| 2258 | |
| 2259 | addr &= PAGE_MASK; |
| 2260 | vma = find_vma(mm, addr); |
| 2261 | if (!vma) |
| 2262 | return NULL; |
| 2263 | if (vma->vm_start <= addr) |
| 2264 | return vma; |
| 2265 | start = vma->vm_start; |
| 2266 | if (expand_stack_locked(vma, addr)) |
| 2267 | return NULL; |
| 2268 | if (vma->vm_flags & VM_LOCKED) |
| 2269 | populate_vma_page_range(vma, addr, start, NULL); |
| 2270 | return vma; |
| 2271 | } |
| 2272 | #endif |
| 2273 | |
| 2274 | #if defined(CONFIG_STACK_GROWSUP) |
| 2275 | |
| 2276 | #define vma_expand_up(vma,addr) expand_upwards(vma, addr) |
| 2277 | #define vma_expand_down(vma, addr) (-EFAULT) |
| 2278 | |
| 2279 | #else |
| 2280 | |
| 2281 | #define vma_expand_up(vma,addr) (-EFAULT) |
| 2282 | #define vma_expand_down(vma, addr) expand_downwards(vma, addr) |
| 2283 | |
| 2284 | #endif |
| 2285 | |
| 2286 | /* |
| 2287 | * expand_stack(): legacy interface for page faulting. Don't use unless |
| 2288 | * you have to. |
| 2289 | * |
| 2290 | * This is called with the mm locked for reading, drops the lock, takes |
| 2291 | * the lock for writing, tries to look up a vma again, expands it if |
| 2292 | * necessary, and downgrades the lock to reading again. |
| 2293 | * |
| 2294 | * If no vma is found or it can't be expanded, it returns NULL and has |
| 2295 | * dropped the lock. |
| 2296 | */ |
| 2297 | struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr) |
| 2298 | { |
| 2299 | struct vm_area_struct *vma, *prev; |
| 2300 | |
| 2301 | mmap_read_unlock(mm); |
| 2302 | if (mmap_write_lock_killable(mm)) |
| 2303 | return NULL; |
| 2304 | |
| 2305 | vma = find_vma_prev(mm, addr, &prev); |
| 2306 | if (vma && vma->vm_start <= addr) |
| 2307 | goto success; |
| 2308 | |
| 2309 | if (prev && !vma_expand_up(prev, addr)) { |
| 2310 | vma = prev; |
| 2311 | goto success; |
| 2312 | } |
| 2313 | |
| 2314 | if (vma && !vma_expand_down(vma, addr)) |
| 2315 | goto success; |
| 2316 | |
| 2317 | mmap_write_unlock(mm); |
| 2318 | return NULL; |
| 2319 | |
| 2320 | success: |
| 2321 | mmap_write_downgrade(mm); |
| 2322 | return vma; |
| 2323 | } |
| 2324 | |
| 2325 | /* |
| 2326 | * Ok - we have the memory areas we should free on a maple tree so release them, |
| 2327 | * and do the vma updates. |
| 2328 | * |
| 2329 | * Called with the mm semaphore held. |
| 2330 | */ |
| 2331 | static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas) |
| 2332 | { |
| 2333 | unsigned long nr_accounted = 0; |
| 2334 | struct vm_area_struct *vma; |
| 2335 | |
| 2336 | /* Update high watermark before we lower total_vm */ |
| 2337 | update_hiwater_vm(mm); |
| 2338 | mas_for_each(mas, vma, ULONG_MAX) { |
| 2339 | long nrpages = vma_pages(vma); |
| 2340 | |
| 2341 | if (vma->vm_flags & VM_ACCOUNT) |
| 2342 | nr_accounted += nrpages; |
| 2343 | vm_stat_account(mm, vma->vm_flags, -nrpages); |
| 2344 | remove_vma(vma, false); |
| 2345 | } |
| 2346 | vm_unacct_memory(nr_accounted); |
| 2347 | } |
| 2348 | |
| 2349 | /* |
| 2350 | * Get rid of page table information in the indicated region. |
| 2351 | * |
| 2352 | * Called with the mm semaphore held. |
| 2353 | */ |
| 2354 | static void unmap_region(struct mm_struct *mm, struct ma_state *mas, |
| 2355 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
| 2356 | struct vm_area_struct *next, unsigned long start, |
| 2357 | unsigned long end, unsigned long tree_end, bool mm_wr_locked) |
| 2358 | { |
| 2359 | struct mmu_gather tlb; |
| 2360 | unsigned long mt_start = mas->index; |
| 2361 | |
| 2362 | lru_add_drain(); |
| 2363 | tlb_gather_mmu(&tlb, mm); |
| 2364 | update_hiwater_rss(mm); |
| 2365 | unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked); |
| 2366 | mas_set(mas, mt_start); |
| 2367 | free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, |
| 2368 | next ? next->vm_start : USER_PGTABLES_CEILING, |
| 2369 | mm_wr_locked); |
| 2370 | tlb_finish_mmu(&tlb); |
| 2371 | } |
| 2372 | |
| 2373 | /* |
| 2374 | * __split_vma() bypasses sysctl_max_map_count checking. We use this where it |
| 2375 | * has already been checked or doesn't make sense to fail. |
| 2376 | * VMA Iterator will point to the end VMA. |
| 2377 | */ |
| 2378 | static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 2379 | unsigned long addr, int new_below) |
| 2380 | { |
| 2381 | struct vma_prepare vp; |
| 2382 | struct vm_area_struct *new; |
| 2383 | int err; |
| 2384 | |
| 2385 | WARN_ON(vma->vm_start >= addr); |
| 2386 | WARN_ON(vma->vm_end <= addr); |
| 2387 | |
| 2388 | if (vma->vm_ops && vma->vm_ops->may_split) { |
| 2389 | err = vma->vm_ops->may_split(vma, addr); |
| 2390 | if (err) |
| 2391 | return err; |
| 2392 | } |
| 2393 | |
| 2394 | new = vm_area_dup(vma); |
| 2395 | if (!new) |
| 2396 | return -ENOMEM; |
| 2397 | |
| 2398 | if (new_below) { |
| 2399 | new->vm_end = addr; |
| 2400 | } else { |
| 2401 | new->vm_start = addr; |
| 2402 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); |
| 2403 | } |
| 2404 | |
| 2405 | err = -ENOMEM; |
| 2406 | vma_iter_config(vmi, new->vm_start, new->vm_end); |
| 2407 | if (vma_iter_prealloc(vmi, new)) |
| 2408 | goto out_free_vma; |
| 2409 | |
| 2410 | err = vma_dup_policy(vma, new); |
| 2411 | if (err) |
| 2412 | goto out_free_vmi; |
| 2413 | |
| 2414 | err = anon_vma_clone(new, vma); |
| 2415 | if (err) |
| 2416 | goto out_free_mpol; |
| 2417 | |
| 2418 | if (new->vm_file) |
| 2419 | get_file(new->vm_file); |
| 2420 | |
| 2421 | if (new->vm_ops && new->vm_ops->open) |
| 2422 | new->vm_ops->open(new); |
| 2423 | |
| 2424 | vma_start_write(vma); |
| 2425 | vma_start_write(new); |
| 2426 | |
| 2427 | init_vma_prep(&vp, vma); |
| 2428 | vp.insert = new; |
| 2429 | vma_prepare(&vp); |
| 2430 | vma_adjust_trans_huge(vma, vma->vm_start, addr, 0); |
| 2431 | |
| 2432 | if (new_below) { |
| 2433 | vma->vm_start = addr; |
| 2434 | vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT; |
| 2435 | } else { |
| 2436 | vma->vm_end = addr; |
| 2437 | } |
| 2438 | |
| 2439 | /* vma_complete stores the new vma */ |
| 2440 | vma_complete(&vp, vmi, vma->vm_mm); |
| 2441 | |
| 2442 | /* Success. */ |
| 2443 | if (new_below) |
| 2444 | vma_next(vmi); |
| 2445 | return 0; |
| 2446 | |
| 2447 | out_free_mpol: |
| 2448 | mpol_put(vma_policy(new)); |
| 2449 | out_free_vmi: |
| 2450 | vma_iter_free(vmi); |
| 2451 | out_free_vma: |
| 2452 | vm_area_free(new); |
| 2453 | return err; |
| 2454 | } |
| 2455 | |
| 2456 | /* |
| 2457 | * Split a vma into two pieces at address 'addr', a new vma is allocated |
| 2458 | * either for the first part or the tail. |
| 2459 | */ |
| 2460 | static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 2461 | unsigned long addr, int new_below) |
| 2462 | { |
| 2463 | if (vma->vm_mm->map_count >= sysctl_max_map_count) |
| 2464 | return -ENOMEM; |
| 2465 | |
| 2466 | return __split_vma(vmi, vma, addr, new_below); |
| 2467 | } |
| 2468 | |
| 2469 | /* |
| 2470 | * We are about to modify one or multiple of a VMA's flags, policy, userfaultfd |
| 2471 | * context and anonymous VMA name within the range [start, end). |
| 2472 | * |
| 2473 | * As a result, we might be able to merge the newly modified VMA range with an |
| 2474 | * adjacent VMA with identical properties. |
| 2475 | * |
| 2476 | * If no merge is possible and the range does not span the entirety of the VMA, |
| 2477 | * we then need to split the VMA to accommodate the change. |
| 2478 | * |
| 2479 | * The function returns either the merged VMA, the original VMA if a split was |
| 2480 | * required instead, or an error if the split failed. |
| 2481 | */ |
| 2482 | struct vm_area_struct *vma_modify(struct vma_iterator *vmi, |
| 2483 | struct vm_area_struct *prev, |
| 2484 | struct vm_area_struct *vma, |
| 2485 | unsigned long start, unsigned long end, |
| 2486 | unsigned long vm_flags, |
| 2487 | struct mempolicy *policy, |
| 2488 | struct vm_userfaultfd_ctx uffd_ctx, |
| 2489 | struct anon_vma_name *anon_name) |
| 2490 | { |
| 2491 | pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
| 2492 | struct vm_area_struct *merged; |
| 2493 | |
| 2494 | merged = vma_merge(vmi, prev, vma, start, end, vm_flags, |
| 2495 | pgoff, policy, uffd_ctx, anon_name); |
| 2496 | if (merged) |
| 2497 | return merged; |
| 2498 | |
| 2499 | if (vma->vm_start < start) { |
| 2500 | int err = split_vma(vmi, vma, start, 1); |
| 2501 | |
| 2502 | if (err) |
| 2503 | return ERR_PTR(err); |
| 2504 | } |
| 2505 | |
| 2506 | if (vma->vm_end > end) { |
| 2507 | int err = split_vma(vmi, vma, end, 0); |
| 2508 | |
| 2509 | if (err) |
| 2510 | return ERR_PTR(err); |
| 2511 | } |
| 2512 | |
| 2513 | return vma; |
| 2514 | } |
| 2515 | |
| 2516 | /* |
| 2517 | * Attempt to merge a newly mapped VMA with those adjacent to it. The caller |
| 2518 | * must ensure that [start, end) does not overlap any existing VMA. |
| 2519 | */ |
| 2520 | static struct vm_area_struct |
| 2521 | *vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev, |
| 2522 | struct vm_area_struct *vma, unsigned long start, |
| 2523 | unsigned long end, pgoff_t pgoff) |
| 2524 | { |
| 2525 | return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff, |
| 2526 | vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma)); |
| 2527 | } |
| 2528 | |
| 2529 | /* |
| 2530 | * Expand vma by delta bytes, potentially merging with an immediately adjacent |
| 2531 | * VMA with identical properties. |
| 2532 | */ |
| 2533 | struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi, |
| 2534 | struct vm_area_struct *vma, |
| 2535 | unsigned long delta) |
| 2536 | { |
| 2537 | pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma); |
| 2538 | |
| 2539 | /* vma is specified as prev, so case 1 or 2 will apply. */ |
| 2540 | return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta, |
| 2541 | vma->vm_flags, pgoff, vma_policy(vma), |
| 2542 | vma->vm_userfaultfd_ctx, anon_vma_name(vma)); |
| 2543 | } |
| 2544 | |
| 2545 | /* |
| 2546 | * do_vmi_align_munmap() - munmap the aligned region from @start to @end. |
| 2547 | * @vmi: The vma iterator |
| 2548 | * @vma: The starting vm_area_struct |
| 2549 | * @mm: The mm_struct |
| 2550 | * @start: The aligned start address to munmap. |
| 2551 | * @end: The aligned end address to munmap. |
| 2552 | * @uf: The userfaultfd list_head |
| 2553 | * @unlock: Set to true to drop the mmap_lock. unlocking only happens on |
| 2554 | * success. |
| 2555 | * |
| 2556 | * Return: 0 on success and drops the lock if so directed, error and leaves the |
| 2557 | * lock held otherwise. |
| 2558 | */ |
| 2559 | static int |
| 2560 | do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 2561 | struct mm_struct *mm, unsigned long start, |
| 2562 | unsigned long end, struct list_head *uf, bool unlock) |
| 2563 | { |
| 2564 | struct vm_area_struct *prev, *next = NULL; |
| 2565 | struct maple_tree mt_detach; |
| 2566 | int count = 0; |
| 2567 | int error = -ENOMEM; |
| 2568 | unsigned long locked_vm = 0; |
| 2569 | MA_STATE(mas_detach, &mt_detach, 0, 0); |
| 2570 | mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK); |
| 2571 | mt_on_stack(mt_detach); |
| 2572 | |
| 2573 | /* |
| 2574 | * If we need to split any vma, do it now to save pain later. |
| 2575 | * |
| 2576 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially |
| 2577 | * unmapped vm_area_struct will remain in use: so lower split_vma |
| 2578 | * places tmp vma above, and higher split_vma places tmp vma below. |
| 2579 | */ |
| 2580 | |
| 2581 | /* Does it split the first one? */ |
| 2582 | if (start > vma->vm_start) { |
| 2583 | |
| 2584 | /* |
| 2585 | * Make sure that map_count on return from munmap() will |
| 2586 | * not exceed its limit; but let map_count go just above |
| 2587 | * its limit temporarily, to help free resources as expected. |
| 2588 | */ |
| 2589 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) |
| 2590 | goto map_count_exceeded; |
| 2591 | |
| 2592 | error = __split_vma(vmi, vma, start, 1); |
| 2593 | if (error) |
| 2594 | goto start_split_failed; |
| 2595 | } |
| 2596 | |
| 2597 | /* |
| 2598 | * Detach a range of VMAs from the mm. Using next as a temp variable as |
| 2599 | * it is always overwritten. |
| 2600 | */ |
| 2601 | next = vma; |
| 2602 | do { |
| 2603 | /* Does it split the end? */ |
| 2604 | if (next->vm_end > end) { |
| 2605 | error = __split_vma(vmi, next, end, 0); |
| 2606 | if (error) |
| 2607 | goto end_split_failed; |
| 2608 | } |
| 2609 | vma_start_write(next); |
| 2610 | mas_set(&mas_detach, count); |
| 2611 | error = mas_store_gfp(&mas_detach, next, GFP_KERNEL); |
| 2612 | if (error) |
| 2613 | goto munmap_gather_failed; |
| 2614 | vma_mark_detached(next, true); |
| 2615 | if (next->vm_flags & VM_LOCKED) |
| 2616 | locked_vm += vma_pages(next); |
| 2617 | |
| 2618 | count++; |
| 2619 | if (unlikely(uf)) { |
| 2620 | /* |
| 2621 | * If userfaultfd_unmap_prep returns an error the vmas |
| 2622 | * will remain split, but userland will get a |
| 2623 | * highly unexpected error anyway. This is no |
| 2624 | * different than the case where the first of the two |
| 2625 | * __split_vma fails, but we don't undo the first |
| 2626 | * split, despite we could. This is unlikely enough |
| 2627 | * failure that it's not worth optimizing it for. |
| 2628 | */ |
| 2629 | error = userfaultfd_unmap_prep(next, start, end, uf); |
| 2630 | |
| 2631 | if (error) |
| 2632 | goto userfaultfd_error; |
| 2633 | } |
| 2634 | #ifdef CONFIG_DEBUG_VM_MAPLE_TREE |
| 2635 | BUG_ON(next->vm_start < start); |
| 2636 | BUG_ON(next->vm_start > end); |
| 2637 | #endif |
| 2638 | } for_each_vma_range(*vmi, next, end); |
| 2639 | |
| 2640 | #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) |
| 2641 | /* Make sure no VMAs are about to be lost. */ |
| 2642 | { |
| 2643 | MA_STATE(test, &mt_detach, 0, 0); |
| 2644 | struct vm_area_struct *vma_mas, *vma_test; |
| 2645 | int test_count = 0; |
| 2646 | |
| 2647 | vma_iter_set(vmi, start); |
| 2648 | rcu_read_lock(); |
| 2649 | vma_test = mas_find(&test, count - 1); |
| 2650 | for_each_vma_range(*vmi, vma_mas, end) { |
| 2651 | BUG_ON(vma_mas != vma_test); |
| 2652 | test_count++; |
| 2653 | vma_test = mas_next(&test, count - 1); |
| 2654 | } |
| 2655 | rcu_read_unlock(); |
| 2656 | BUG_ON(count != test_count); |
| 2657 | } |
| 2658 | #endif |
| 2659 | |
| 2660 | while (vma_iter_addr(vmi) > start) |
| 2661 | vma_iter_prev_range(vmi); |
| 2662 | |
| 2663 | error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL); |
| 2664 | if (error) |
| 2665 | goto clear_tree_failed; |
| 2666 | |
| 2667 | /* Point of no return */ |
| 2668 | mm->locked_vm -= locked_vm; |
| 2669 | mm->map_count -= count; |
| 2670 | if (unlock) |
| 2671 | mmap_write_downgrade(mm); |
| 2672 | |
| 2673 | prev = vma_iter_prev_range(vmi); |
| 2674 | next = vma_next(vmi); |
| 2675 | if (next) |
| 2676 | vma_iter_prev_range(vmi); |
| 2677 | |
| 2678 | /* |
| 2679 | * We can free page tables without write-locking mmap_lock because VMAs |
| 2680 | * were isolated before we downgraded mmap_lock. |
| 2681 | */ |
| 2682 | mas_set(&mas_detach, 1); |
| 2683 | unmap_region(mm, &mas_detach, vma, prev, next, start, end, count, |
| 2684 | !unlock); |
| 2685 | /* Statistics and freeing VMAs */ |
| 2686 | mas_set(&mas_detach, 0); |
| 2687 | remove_mt(mm, &mas_detach); |
| 2688 | validate_mm(mm); |
| 2689 | if (unlock) |
| 2690 | mmap_read_unlock(mm); |
| 2691 | |
| 2692 | __mt_destroy(&mt_detach); |
| 2693 | return 0; |
| 2694 | |
| 2695 | clear_tree_failed: |
| 2696 | userfaultfd_error: |
| 2697 | munmap_gather_failed: |
| 2698 | end_split_failed: |
| 2699 | mas_set(&mas_detach, 0); |
| 2700 | mas_for_each(&mas_detach, next, end) |
| 2701 | vma_mark_detached(next, false); |
| 2702 | |
| 2703 | __mt_destroy(&mt_detach); |
| 2704 | start_split_failed: |
| 2705 | map_count_exceeded: |
| 2706 | validate_mm(mm); |
| 2707 | return error; |
| 2708 | } |
| 2709 | |
| 2710 | /* |
| 2711 | * do_vmi_munmap() - munmap a given range. |
| 2712 | * @vmi: The vma iterator |
| 2713 | * @mm: The mm_struct |
| 2714 | * @start: The start address to munmap |
| 2715 | * @len: The length of the range to munmap |
| 2716 | * @uf: The userfaultfd list_head |
| 2717 | * @unlock: set to true if the user wants to drop the mmap_lock on success |
| 2718 | * |
| 2719 | * This function takes a @mas that is either pointing to the previous VMA or set |
| 2720 | * to MA_START and sets it up to remove the mapping(s). The @len will be |
| 2721 | * aligned and any arch_unmap work will be preformed. |
| 2722 | * |
| 2723 | * Return: 0 on success and drops the lock if so directed, error and leaves the |
| 2724 | * lock held otherwise. |
| 2725 | */ |
| 2726 | int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, |
| 2727 | unsigned long start, size_t len, struct list_head *uf, |
| 2728 | bool unlock) |
| 2729 | { |
| 2730 | unsigned long end; |
| 2731 | struct vm_area_struct *vma; |
| 2732 | |
| 2733 | if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) |
| 2734 | return -EINVAL; |
| 2735 | |
| 2736 | end = start + PAGE_ALIGN(len); |
| 2737 | if (end == start) |
| 2738 | return -EINVAL; |
| 2739 | |
| 2740 | /* |
| 2741 | * Check if memory is sealed before arch_unmap. |
| 2742 | * Prevent unmapping a sealed VMA. |
| 2743 | * can_modify_mm assumes we have acquired the lock on MM. |
| 2744 | */ |
| 2745 | if (unlikely(!can_modify_mm(mm, start, end))) |
| 2746 | return -EPERM; |
| 2747 | |
| 2748 | /* arch_unmap() might do unmaps itself. */ |
| 2749 | arch_unmap(mm, start, end); |
| 2750 | |
| 2751 | /* Find the first overlapping VMA */ |
| 2752 | vma = vma_find(vmi, end); |
| 2753 | if (!vma) { |
| 2754 | if (unlock) |
| 2755 | mmap_write_unlock(mm); |
| 2756 | return 0; |
| 2757 | } |
| 2758 | |
| 2759 | return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock); |
| 2760 | } |
| 2761 | |
| 2762 | /* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls. |
| 2763 | * @mm: The mm_struct |
| 2764 | * @start: The start address to munmap |
| 2765 | * @len: The length to be munmapped. |
| 2766 | * @uf: The userfaultfd list_head |
| 2767 | * |
| 2768 | * Return: 0 on success, error otherwise. |
| 2769 | */ |
| 2770 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, |
| 2771 | struct list_head *uf) |
| 2772 | { |
| 2773 | VMA_ITERATOR(vmi, mm, start); |
| 2774 | |
| 2775 | return do_vmi_munmap(&vmi, mm, start, len, uf, false); |
| 2776 | } |
| 2777 | |
| 2778 | unsigned long mmap_region(struct file *file, unsigned long addr, |
| 2779 | unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, |
| 2780 | struct list_head *uf) |
| 2781 | { |
| 2782 | struct mm_struct *mm = current->mm; |
| 2783 | struct vm_area_struct *vma = NULL; |
| 2784 | struct vm_area_struct *next, *prev, *merge; |
| 2785 | pgoff_t pglen = len >> PAGE_SHIFT; |
| 2786 | unsigned long charged = 0; |
| 2787 | unsigned long end = addr + len; |
| 2788 | unsigned long merge_start = addr, merge_end = end; |
| 2789 | bool writable_file_mapping = false; |
| 2790 | pgoff_t vm_pgoff; |
| 2791 | int error; |
| 2792 | VMA_ITERATOR(vmi, mm, addr); |
| 2793 | |
| 2794 | /* Check against address space limit. */ |
| 2795 | if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { |
| 2796 | unsigned long nr_pages; |
| 2797 | |
| 2798 | /* |
| 2799 | * MAP_FIXED may remove pages of mappings that intersects with |
| 2800 | * requested mapping. Account for the pages it would unmap. |
| 2801 | */ |
| 2802 | nr_pages = count_vma_pages_range(mm, addr, end); |
| 2803 | |
| 2804 | if (!may_expand_vm(mm, vm_flags, |
| 2805 | (len >> PAGE_SHIFT) - nr_pages)) |
| 2806 | return -ENOMEM; |
| 2807 | } |
| 2808 | |
| 2809 | /* Unmap any existing mapping in the area */ |
| 2810 | error = do_vmi_munmap(&vmi, mm, addr, len, uf, false); |
| 2811 | if (error == -EPERM) |
| 2812 | return error; |
| 2813 | else if (error) |
| 2814 | return -ENOMEM; |
| 2815 | |
| 2816 | /* |
| 2817 | * Private writable mapping: check memory availability |
| 2818 | */ |
| 2819 | if (accountable_mapping(file, vm_flags)) { |
| 2820 | charged = len >> PAGE_SHIFT; |
| 2821 | if (security_vm_enough_memory_mm(mm, charged)) |
| 2822 | return -ENOMEM; |
| 2823 | vm_flags |= VM_ACCOUNT; |
| 2824 | } |
| 2825 | |
| 2826 | next = vma_next(&vmi); |
| 2827 | prev = vma_prev(&vmi); |
| 2828 | if (vm_flags & VM_SPECIAL) { |
| 2829 | if (prev) |
| 2830 | vma_iter_next_range(&vmi); |
| 2831 | goto cannot_expand; |
| 2832 | } |
| 2833 | |
| 2834 | /* Attempt to expand an old mapping */ |
| 2835 | /* Check next */ |
| 2836 | if (next && next->vm_start == end && !vma_policy(next) && |
| 2837 | can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen, |
| 2838 | NULL_VM_UFFD_CTX, NULL)) { |
| 2839 | merge_end = next->vm_end; |
| 2840 | vma = next; |
| 2841 | vm_pgoff = next->vm_pgoff - pglen; |
| 2842 | } |
| 2843 | |
| 2844 | /* Check prev */ |
| 2845 | if (prev && prev->vm_end == addr && !vma_policy(prev) && |
| 2846 | (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file, |
| 2847 | pgoff, vma->vm_userfaultfd_ctx, NULL) : |
| 2848 | can_vma_merge_after(prev, vm_flags, NULL, file, pgoff, |
| 2849 | NULL_VM_UFFD_CTX, NULL))) { |
| 2850 | merge_start = prev->vm_start; |
| 2851 | vma = prev; |
| 2852 | vm_pgoff = prev->vm_pgoff; |
| 2853 | } else if (prev) { |
| 2854 | vma_iter_next_range(&vmi); |
| 2855 | } |
| 2856 | |
| 2857 | /* Actually expand, if possible */ |
| 2858 | if (vma && |
| 2859 | !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) { |
| 2860 | khugepaged_enter_vma(vma, vm_flags); |
| 2861 | goto expanded; |
| 2862 | } |
| 2863 | |
| 2864 | if (vma == prev) |
| 2865 | vma_iter_set(&vmi, addr); |
| 2866 | cannot_expand: |
| 2867 | |
| 2868 | /* |
| 2869 | * Determine the object being mapped and call the appropriate |
| 2870 | * specific mapper. the address has already been validated, but |
| 2871 | * not unmapped, but the maps are removed from the list. |
| 2872 | */ |
| 2873 | vma = vm_area_alloc(mm); |
| 2874 | if (!vma) { |
| 2875 | error = -ENOMEM; |
| 2876 | goto unacct_error; |
| 2877 | } |
| 2878 | |
| 2879 | vma_iter_config(&vmi, addr, end); |
| 2880 | vma_set_range(vma, addr, end, pgoff); |
| 2881 | vm_flags_init(vma, vm_flags); |
| 2882 | vma->vm_page_prot = vm_get_page_prot(vm_flags); |
| 2883 | |
| 2884 | if (file) { |
| 2885 | vma->vm_file = get_file(file); |
| 2886 | error = call_mmap(file, vma); |
| 2887 | if (error) |
| 2888 | goto unmap_and_free_vma; |
| 2889 | |
| 2890 | if (vma_is_shared_maywrite(vma)) { |
| 2891 | error = mapping_map_writable(file->f_mapping); |
| 2892 | if (error) |
| 2893 | goto close_and_free_vma; |
| 2894 | |
| 2895 | writable_file_mapping = true; |
| 2896 | } |
| 2897 | |
| 2898 | /* |
| 2899 | * Expansion is handled above, merging is handled below. |
| 2900 | * Drivers should not alter the address of the VMA. |
| 2901 | */ |
| 2902 | error = -EINVAL; |
| 2903 | if (WARN_ON((addr != vma->vm_start))) |
| 2904 | goto close_and_free_vma; |
| 2905 | |
| 2906 | vma_iter_config(&vmi, addr, end); |
| 2907 | /* |
| 2908 | * If vm_flags changed after call_mmap(), we should try merge |
| 2909 | * vma again as we may succeed this time. |
| 2910 | */ |
| 2911 | if (unlikely(vm_flags != vma->vm_flags && prev)) { |
| 2912 | merge = vma_merge_new_vma(&vmi, prev, vma, |
| 2913 | vma->vm_start, vma->vm_end, |
| 2914 | vma->vm_pgoff); |
| 2915 | if (merge) { |
| 2916 | /* |
| 2917 | * ->mmap() can change vma->vm_file and fput |
| 2918 | * the original file. So fput the vma->vm_file |
| 2919 | * here or we would add an extra fput for file |
| 2920 | * and cause general protection fault |
| 2921 | * ultimately. |
| 2922 | */ |
| 2923 | fput(vma->vm_file); |
| 2924 | vm_area_free(vma); |
| 2925 | vma = merge; |
| 2926 | /* Update vm_flags to pick up the change. */ |
| 2927 | vm_flags = vma->vm_flags; |
| 2928 | goto unmap_writable; |
| 2929 | } |
| 2930 | } |
| 2931 | |
| 2932 | vm_flags = vma->vm_flags; |
| 2933 | } else if (vm_flags & VM_SHARED) { |
| 2934 | error = shmem_zero_setup(vma); |
| 2935 | if (error) |
| 2936 | goto free_vma; |
| 2937 | } else { |
| 2938 | vma_set_anonymous(vma); |
| 2939 | } |
| 2940 | |
| 2941 | if (map_deny_write_exec(vma, vma->vm_flags)) { |
| 2942 | error = -EACCES; |
| 2943 | goto close_and_free_vma; |
| 2944 | } |
| 2945 | |
| 2946 | /* Allow architectures to sanity-check the vm_flags */ |
| 2947 | error = -EINVAL; |
| 2948 | if (!arch_validate_flags(vma->vm_flags)) |
| 2949 | goto close_and_free_vma; |
| 2950 | |
| 2951 | error = -ENOMEM; |
| 2952 | if (vma_iter_prealloc(&vmi, vma)) |
| 2953 | goto close_and_free_vma; |
| 2954 | |
| 2955 | /* Lock the VMA since it is modified after insertion into VMA tree */ |
| 2956 | vma_start_write(vma); |
| 2957 | vma_iter_store(&vmi, vma); |
| 2958 | mm->map_count++; |
| 2959 | vma_link_file(vma); |
| 2960 | |
| 2961 | /* |
| 2962 | * vma_merge() calls khugepaged_enter_vma() either, the below |
| 2963 | * call covers the non-merge case. |
| 2964 | */ |
| 2965 | khugepaged_enter_vma(vma, vma->vm_flags); |
| 2966 | |
| 2967 | /* Once vma denies write, undo our temporary denial count */ |
| 2968 | unmap_writable: |
| 2969 | if (writable_file_mapping) |
| 2970 | mapping_unmap_writable(file->f_mapping); |
| 2971 | file = vma->vm_file; |
| 2972 | ksm_add_vma(vma); |
| 2973 | expanded: |
| 2974 | perf_event_mmap(vma); |
| 2975 | |
| 2976 | vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); |
| 2977 | if (vm_flags & VM_LOCKED) { |
| 2978 | if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || |
| 2979 | is_vm_hugetlb_page(vma) || |
| 2980 | vma == get_gate_vma(current->mm)) |
| 2981 | vm_flags_clear(vma, VM_LOCKED_MASK); |
| 2982 | else |
| 2983 | mm->locked_vm += (len >> PAGE_SHIFT); |
| 2984 | } |
| 2985 | |
| 2986 | if (file) |
| 2987 | uprobe_mmap(vma); |
| 2988 | |
| 2989 | /* |
| 2990 | * New (or expanded) vma always get soft dirty status. |
| 2991 | * Otherwise user-space soft-dirty page tracker won't |
| 2992 | * be able to distinguish situation when vma area unmapped, |
| 2993 | * then new mapped in-place (which must be aimed as |
| 2994 | * a completely new data area). |
| 2995 | */ |
| 2996 | vm_flags_set(vma, VM_SOFTDIRTY); |
| 2997 | |
| 2998 | vma_set_page_prot(vma); |
| 2999 | |
| 3000 | validate_mm(mm); |
| 3001 | return addr; |
| 3002 | |
| 3003 | close_and_free_vma: |
| 3004 | if (file && vma->vm_ops && vma->vm_ops->close) |
| 3005 | vma->vm_ops->close(vma); |
| 3006 | |
| 3007 | if (file || vma->vm_file) { |
| 3008 | unmap_and_free_vma: |
| 3009 | fput(vma->vm_file); |
| 3010 | vma->vm_file = NULL; |
| 3011 | |
| 3012 | vma_iter_set(&vmi, vma->vm_end); |
| 3013 | /* Undo any partial mapping done by a device driver. */ |
| 3014 | unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start, |
| 3015 | vma->vm_end, vma->vm_end, true); |
| 3016 | } |
| 3017 | if (writable_file_mapping) |
| 3018 | mapping_unmap_writable(file->f_mapping); |
| 3019 | free_vma: |
| 3020 | vm_area_free(vma); |
| 3021 | unacct_error: |
| 3022 | if (charged) |
| 3023 | vm_unacct_memory(charged); |
| 3024 | validate_mm(mm); |
| 3025 | return error; |
| 3026 | } |
| 3027 | |
| 3028 | static int __vm_munmap(unsigned long start, size_t len, bool unlock) |
| 3029 | { |
| 3030 | int ret; |
| 3031 | struct mm_struct *mm = current->mm; |
| 3032 | LIST_HEAD(uf); |
| 3033 | VMA_ITERATOR(vmi, mm, start); |
| 3034 | |
| 3035 | if (mmap_write_lock_killable(mm)) |
| 3036 | return -EINTR; |
| 3037 | |
| 3038 | ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock); |
| 3039 | if (ret || !unlock) |
| 3040 | mmap_write_unlock(mm); |
| 3041 | |
| 3042 | userfaultfd_unmap_complete(mm, &uf); |
| 3043 | return ret; |
| 3044 | } |
| 3045 | |
| 3046 | int vm_munmap(unsigned long start, size_t len) |
| 3047 | { |
| 3048 | return __vm_munmap(start, len, false); |
| 3049 | } |
| 3050 | EXPORT_SYMBOL(vm_munmap); |
| 3051 | |
| 3052 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
| 3053 | { |
| 3054 | addr = untagged_addr(addr); |
| 3055 | return __vm_munmap(addr, len, true); |
| 3056 | } |
| 3057 | |
| 3058 | |
| 3059 | /* |
| 3060 | * Emulation of deprecated remap_file_pages() syscall. |
| 3061 | */ |
| 3062 | SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, |
| 3063 | unsigned long, prot, unsigned long, pgoff, unsigned long, flags) |
| 3064 | { |
| 3065 | |
| 3066 | struct mm_struct *mm = current->mm; |
| 3067 | struct vm_area_struct *vma; |
| 3068 | unsigned long populate = 0; |
| 3069 | unsigned long ret = -EINVAL; |
| 3070 | struct file *file; |
| 3071 | |
| 3072 | pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n", |
| 3073 | current->comm, current->pid); |
| 3074 | |
| 3075 | if (prot) |
| 3076 | return ret; |
| 3077 | start = start & PAGE_MASK; |
| 3078 | size = size & PAGE_MASK; |
| 3079 | |
| 3080 | if (start + size <= start) |
| 3081 | return ret; |
| 3082 | |
| 3083 | /* Does pgoff wrap? */ |
| 3084 | if (pgoff + (size >> PAGE_SHIFT) < pgoff) |
| 3085 | return ret; |
| 3086 | |
| 3087 | if (mmap_write_lock_killable(mm)) |
| 3088 | return -EINTR; |
| 3089 | |
| 3090 | vma = vma_lookup(mm, start); |
| 3091 | |
| 3092 | if (!vma || !(vma->vm_flags & VM_SHARED)) |
| 3093 | goto out; |
| 3094 | |
| 3095 | if (start + size > vma->vm_end) { |
| 3096 | VMA_ITERATOR(vmi, mm, vma->vm_end); |
| 3097 | struct vm_area_struct *next, *prev = vma; |
| 3098 | |
| 3099 | for_each_vma_range(vmi, next, start + size) { |
| 3100 | /* hole between vmas ? */ |
| 3101 | if (next->vm_start != prev->vm_end) |
| 3102 | goto out; |
| 3103 | |
| 3104 | if (next->vm_file != vma->vm_file) |
| 3105 | goto out; |
| 3106 | |
| 3107 | if (next->vm_flags != vma->vm_flags) |
| 3108 | goto out; |
| 3109 | |
| 3110 | if (start + size <= next->vm_end) |
| 3111 | break; |
| 3112 | |
| 3113 | prev = next; |
| 3114 | } |
| 3115 | |
| 3116 | if (!next) |
| 3117 | goto out; |
| 3118 | } |
| 3119 | |
| 3120 | prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; |
| 3121 | prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; |
| 3122 | prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; |
| 3123 | |
| 3124 | flags &= MAP_NONBLOCK; |
| 3125 | flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; |
| 3126 | if (vma->vm_flags & VM_LOCKED) |
| 3127 | flags |= MAP_LOCKED; |
| 3128 | |
| 3129 | file = get_file(vma->vm_file); |
| 3130 | ret = do_mmap(vma->vm_file, start, size, |
| 3131 | prot, flags, 0, pgoff, &populate, NULL); |
| 3132 | fput(file); |
| 3133 | out: |
| 3134 | mmap_write_unlock(mm); |
| 3135 | if (populate) |
| 3136 | mm_populate(ret, populate); |
| 3137 | if (!IS_ERR_VALUE(ret)) |
| 3138 | ret = 0; |
| 3139 | return ret; |
| 3140 | } |
| 3141 | |
| 3142 | /* |
| 3143 | * do_vma_munmap() - Unmap a full or partial vma. |
| 3144 | * @vmi: The vma iterator pointing at the vma |
| 3145 | * @vma: The first vma to be munmapped |
| 3146 | * @start: the start of the address to unmap |
| 3147 | * @end: The end of the address to unmap |
| 3148 | * @uf: The userfaultfd list_head |
| 3149 | * @unlock: Drop the lock on success |
| 3150 | * |
| 3151 | * unmaps a VMA mapping when the vma iterator is already in position. |
| 3152 | * Does not handle alignment. |
| 3153 | * |
| 3154 | * Return: 0 on success drops the lock of so directed, error on failure and will |
| 3155 | * still hold the lock. |
| 3156 | */ |
| 3157 | int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 3158 | unsigned long start, unsigned long end, struct list_head *uf, |
| 3159 | bool unlock) |
| 3160 | { |
| 3161 | struct mm_struct *mm = vma->vm_mm; |
| 3162 | |
| 3163 | /* |
| 3164 | * Check if memory is sealed before arch_unmap. |
| 3165 | * Prevent unmapping a sealed VMA. |
| 3166 | * can_modify_mm assumes we have acquired the lock on MM. |
| 3167 | */ |
| 3168 | if (unlikely(!can_modify_mm(mm, start, end))) |
| 3169 | return -EPERM; |
| 3170 | |
| 3171 | arch_unmap(mm, start, end); |
| 3172 | return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock); |
| 3173 | } |
| 3174 | |
| 3175 | /* |
| 3176 | * do_brk_flags() - Increase the brk vma if the flags match. |
| 3177 | * @vmi: The vma iterator |
| 3178 | * @addr: The start address |
| 3179 | * @len: The length of the increase |
| 3180 | * @vma: The vma, |
| 3181 | * @flags: The VMA Flags |
| 3182 | * |
| 3183 | * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags |
| 3184 | * do not match then create a new anonymous VMA. Eventually we may be able to |
| 3185 | * do some brk-specific accounting here. |
| 3186 | */ |
| 3187 | static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| 3188 | unsigned long addr, unsigned long len, unsigned long flags) |
| 3189 | { |
| 3190 | struct mm_struct *mm = current->mm; |
| 3191 | struct vma_prepare vp; |
| 3192 | |
| 3193 | /* |
| 3194 | * Check against address space limits by the changed size |
| 3195 | * Note: This happens *after* clearing old mappings in some code paths. |
| 3196 | */ |
| 3197 | flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; |
| 3198 | if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) |
| 3199 | return -ENOMEM; |
| 3200 | |
| 3201 | if (mm->map_count > sysctl_max_map_count) |
| 3202 | return -ENOMEM; |
| 3203 | |
| 3204 | if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) |
| 3205 | return -ENOMEM; |
| 3206 | |
| 3207 | /* |
| 3208 | * Expand the existing vma if possible; Note that singular lists do not |
| 3209 | * occur after forking, so the expand will only happen on new VMAs. |
| 3210 | */ |
| 3211 | if (vma && vma->vm_end == addr && !vma_policy(vma) && |
| 3212 | can_vma_merge_after(vma, flags, NULL, NULL, |
| 3213 | addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) { |
| 3214 | vma_iter_config(vmi, vma->vm_start, addr + len); |
| 3215 | if (vma_iter_prealloc(vmi, vma)) |
| 3216 | goto unacct_fail; |
| 3217 | |
| 3218 | vma_start_write(vma); |
| 3219 | |
| 3220 | init_vma_prep(&vp, vma); |
| 3221 | vma_prepare(&vp); |
| 3222 | vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0); |
| 3223 | vma->vm_end = addr + len; |
| 3224 | vm_flags_set(vma, VM_SOFTDIRTY); |
| 3225 | vma_iter_store(vmi, vma); |
| 3226 | |
| 3227 | vma_complete(&vp, vmi, mm); |
| 3228 | khugepaged_enter_vma(vma, flags); |
| 3229 | goto out; |
| 3230 | } |
| 3231 | |
| 3232 | if (vma) |
| 3233 | vma_iter_next_range(vmi); |
| 3234 | /* create a vma struct for an anonymous mapping */ |
| 3235 | vma = vm_area_alloc(mm); |
| 3236 | if (!vma) |
| 3237 | goto unacct_fail; |
| 3238 | |
| 3239 | vma_set_anonymous(vma); |
| 3240 | vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT); |
| 3241 | vm_flags_init(vma, flags); |
| 3242 | vma->vm_page_prot = vm_get_page_prot(flags); |
| 3243 | vma_start_write(vma); |
| 3244 | if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) |
| 3245 | goto mas_store_fail; |
| 3246 | |
| 3247 | mm->map_count++; |
| 3248 | validate_mm(mm); |
| 3249 | ksm_add_vma(vma); |
| 3250 | out: |
| 3251 | perf_event_mmap(vma); |
| 3252 | mm->total_vm += len >> PAGE_SHIFT; |
| 3253 | mm->data_vm += len >> PAGE_SHIFT; |
| 3254 | if (flags & VM_LOCKED) |
| 3255 | mm->locked_vm += (len >> PAGE_SHIFT); |
| 3256 | vm_flags_set(vma, VM_SOFTDIRTY); |
| 3257 | return 0; |
| 3258 | |
| 3259 | mas_store_fail: |
| 3260 | vm_area_free(vma); |
| 3261 | unacct_fail: |
| 3262 | vm_unacct_memory(len >> PAGE_SHIFT); |
| 3263 | return -ENOMEM; |
| 3264 | } |
| 3265 | |
| 3266 | int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) |
| 3267 | { |
| 3268 | struct mm_struct *mm = current->mm; |
| 3269 | struct vm_area_struct *vma = NULL; |
| 3270 | unsigned long len; |
| 3271 | int ret; |
| 3272 | bool populate; |
| 3273 | LIST_HEAD(uf); |
| 3274 | VMA_ITERATOR(vmi, mm, addr); |
| 3275 | |
| 3276 | len = PAGE_ALIGN(request); |
| 3277 | if (len < request) |
| 3278 | return -ENOMEM; |
| 3279 | if (!len) |
| 3280 | return 0; |
| 3281 | |
| 3282 | /* Until we need other flags, refuse anything except VM_EXEC. */ |
| 3283 | if ((flags & (~VM_EXEC)) != 0) |
| 3284 | return -EINVAL; |
| 3285 | |
| 3286 | if (mmap_write_lock_killable(mm)) |
| 3287 | return -EINTR; |
| 3288 | |
| 3289 | ret = check_brk_limits(addr, len); |
| 3290 | if (ret) |
| 3291 | goto limits_failed; |
| 3292 | |
| 3293 | ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0); |
| 3294 | if (ret) |
| 3295 | goto munmap_failed; |
| 3296 | |
| 3297 | vma = vma_prev(&vmi); |
| 3298 | ret = do_brk_flags(&vmi, vma, addr, len, flags); |
| 3299 | populate = ((mm->def_flags & VM_LOCKED) != 0); |
| 3300 | mmap_write_unlock(mm); |
| 3301 | userfaultfd_unmap_complete(mm, &uf); |
| 3302 | if (populate && !ret) |
| 3303 | mm_populate(addr, len); |
| 3304 | return ret; |
| 3305 | |
| 3306 | munmap_failed: |
| 3307 | limits_failed: |
| 3308 | mmap_write_unlock(mm); |
| 3309 | return ret; |
| 3310 | } |
| 3311 | EXPORT_SYMBOL(vm_brk_flags); |
| 3312 | |
| 3313 | /* Release all mmaps. */ |
| 3314 | void exit_mmap(struct mm_struct *mm) |
| 3315 | { |
| 3316 | struct mmu_gather tlb; |
| 3317 | struct vm_area_struct *vma; |
| 3318 | unsigned long nr_accounted = 0; |
| 3319 | VMA_ITERATOR(vmi, mm, 0); |
| 3320 | int count = 0; |
| 3321 | |
| 3322 | /* mm's last user has gone, and its about to be pulled down */ |
| 3323 | mmu_notifier_release(mm); |
| 3324 | |
| 3325 | mmap_read_lock(mm); |
| 3326 | arch_exit_mmap(mm); |
| 3327 | |
| 3328 | vma = vma_next(&vmi); |
| 3329 | if (!vma || unlikely(xa_is_zero(vma))) { |
| 3330 | /* Can happen if dup_mmap() received an OOM */ |
| 3331 | mmap_read_unlock(mm); |
| 3332 | mmap_write_lock(mm); |
| 3333 | goto destroy; |
| 3334 | } |
| 3335 | |
| 3336 | lru_add_drain(); |
| 3337 | flush_cache_mm(mm); |
| 3338 | tlb_gather_mmu_fullmm(&tlb, mm); |
| 3339 | /* update_hiwater_rss(mm) here? but nobody should be looking */ |
| 3340 | /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ |
| 3341 | unmap_vmas(&tlb, &vmi.mas, vma, 0, ULONG_MAX, ULONG_MAX, false); |
| 3342 | mmap_read_unlock(mm); |
| 3343 | |
| 3344 | /* |
| 3345 | * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper |
| 3346 | * because the memory has been already freed. |
| 3347 | */ |
| 3348 | set_bit(MMF_OOM_SKIP, &mm->flags); |
| 3349 | mmap_write_lock(mm); |
| 3350 | mt_clear_in_rcu(&mm->mm_mt); |
| 3351 | vma_iter_set(&vmi, vma->vm_end); |
| 3352 | free_pgtables(&tlb, &vmi.mas, vma, FIRST_USER_ADDRESS, |
| 3353 | USER_PGTABLES_CEILING, true); |
| 3354 | tlb_finish_mmu(&tlb); |
| 3355 | |
| 3356 | /* |
| 3357 | * Walk the list again, actually closing and freeing it, with preemption |
| 3358 | * enabled, without holding any MM locks besides the unreachable |
| 3359 | * mmap_write_lock. |
| 3360 | */ |
| 3361 | vma_iter_set(&vmi, vma->vm_end); |
| 3362 | do { |
| 3363 | if (vma->vm_flags & VM_ACCOUNT) |
| 3364 | nr_accounted += vma_pages(vma); |
| 3365 | remove_vma(vma, true); |
| 3366 | count++; |
| 3367 | cond_resched(); |
| 3368 | vma = vma_next(&vmi); |
| 3369 | } while (vma && likely(!xa_is_zero(vma))); |
| 3370 | |
| 3371 | BUG_ON(count != mm->map_count); |
| 3372 | |
| 3373 | trace_exit_mmap(mm); |
| 3374 | destroy: |
| 3375 | __mt_destroy(&mm->mm_mt); |
| 3376 | mmap_write_unlock(mm); |
| 3377 | vm_unacct_memory(nr_accounted); |
| 3378 | } |
| 3379 | |
| 3380 | /* Insert vm structure into process list sorted by address |
| 3381 | * and into the inode's i_mmap tree. If vm_file is non-NULL |
| 3382 | * then i_mmap_rwsem is taken here. |
| 3383 | */ |
| 3384 | int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| 3385 | { |
| 3386 | unsigned long charged = vma_pages(vma); |
| 3387 | |
| 3388 | |
| 3389 | if (find_vma_intersection(mm, vma->vm_start, vma->vm_end)) |
| 3390 | return -ENOMEM; |
| 3391 | |
| 3392 | if ((vma->vm_flags & VM_ACCOUNT) && |
| 3393 | security_vm_enough_memory_mm(mm, charged)) |
| 3394 | return -ENOMEM; |
| 3395 | |
| 3396 | /* |
| 3397 | * The vm_pgoff of a purely anonymous vma should be irrelevant |
| 3398 | * until its first write fault, when page's anon_vma and index |
| 3399 | * are set. But now set the vm_pgoff it will almost certainly |
| 3400 | * end up with (unless mremap moves it elsewhere before that |
| 3401 | * first wfault), so /proc/pid/maps tells a consistent story. |
| 3402 | * |
| 3403 | * By setting it to reflect the virtual start address of the |
| 3404 | * vma, merges and splits can happen in a seamless way, just |
| 3405 | * using the existing file pgoff checks and manipulations. |
| 3406 | * Similarly in do_mmap and in do_brk_flags. |
| 3407 | */ |
| 3408 | if (vma_is_anonymous(vma)) { |
| 3409 | BUG_ON(vma->anon_vma); |
| 3410 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
| 3411 | } |
| 3412 | |
| 3413 | if (vma_link(mm, vma)) { |
| 3414 | if (vma->vm_flags & VM_ACCOUNT) |
| 3415 | vm_unacct_memory(charged); |
| 3416 | return -ENOMEM; |
| 3417 | } |
| 3418 | |
| 3419 | return 0; |
| 3420 | } |
| 3421 | |
| 3422 | /* |
| 3423 | * Copy the vma structure to a new location in the same mm, |
| 3424 | * prior to moving page table entries, to effect an mremap move. |
| 3425 | */ |
| 3426 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, |
| 3427 | unsigned long addr, unsigned long len, pgoff_t pgoff, |
| 3428 | bool *need_rmap_locks) |
| 3429 | { |
| 3430 | struct vm_area_struct *vma = *vmap; |
| 3431 | unsigned long vma_start = vma->vm_start; |
| 3432 | struct mm_struct *mm = vma->vm_mm; |
| 3433 | struct vm_area_struct *new_vma, *prev; |
| 3434 | bool faulted_in_anon_vma = true; |
| 3435 | VMA_ITERATOR(vmi, mm, addr); |
| 3436 | |
| 3437 | /* |
| 3438 | * If anonymous vma has not yet been faulted, update new pgoff |
| 3439 | * to match new location, to increase its chance of merging. |
| 3440 | */ |
| 3441 | if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { |
| 3442 | pgoff = addr >> PAGE_SHIFT; |
| 3443 | faulted_in_anon_vma = false; |
| 3444 | } |
| 3445 | |
| 3446 | new_vma = find_vma_prev(mm, addr, &prev); |
| 3447 | if (new_vma && new_vma->vm_start < addr + len) |
| 3448 | return NULL; /* should never get here */ |
| 3449 | |
| 3450 | new_vma = vma_merge_new_vma(&vmi, prev, vma, addr, addr + len, pgoff); |
| 3451 | if (new_vma) { |
| 3452 | /* |
| 3453 | * Source vma may have been merged into new_vma |
| 3454 | */ |
| 3455 | if (unlikely(vma_start >= new_vma->vm_start && |
| 3456 | vma_start < new_vma->vm_end)) { |
| 3457 | /* |
| 3458 | * The only way we can get a vma_merge with |
| 3459 | * self during an mremap is if the vma hasn't |
| 3460 | * been faulted in yet and we were allowed to |
| 3461 | * reset the dst vma->vm_pgoff to the |
| 3462 | * destination address of the mremap to allow |
| 3463 | * the merge to happen. mremap must change the |
| 3464 | * vm_pgoff linearity between src and dst vmas |
| 3465 | * (in turn preventing a vma_merge) to be |
| 3466 | * safe. It is only safe to keep the vm_pgoff |
| 3467 | * linear if there are no pages mapped yet. |
| 3468 | */ |
| 3469 | VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); |
| 3470 | *vmap = vma = new_vma; |
| 3471 | } |
| 3472 | *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); |
| 3473 | } else { |
| 3474 | new_vma = vm_area_dup(vma); |
| 3475 | if (!new_vma) |
| 3476 | goto out; |
| 3477 | vma_set_range(new_vma, addr, addr + len, pgoff); |
| 3478 | if (vma_dup_policy(vma, new_vma)) |
| 3479 | goto out_free_vma; |
| 3480 | if (anon_vma_clone(new_vma, vma)) |
| 3481 | goto out_free_mempol; |
| 3482 | if (new_vma->vm_file) |
| 3483 | get_file(new_vma->vm_file); |
| 3484 | if (new_vma->vm_ops && new_vma->vm_ops->open) |
| 3485 | new_vma->vm_ops->open(new_vma); |
| 3486 | if (vma_link(mm, new_vma)) |
| 3487 | goto out_vma_link; |
| 3488 | *need_rmap_locks = false; |
| 3489 | } |
| 3490 | return new_vma; |
| 3491 | |
| 3492 | out_vma_link: |
| 3493 | if (new_vma->vm_ops && new_vma->vm_ops->close) |
| 3494 | new_vma->vm_ops->close(new_vma); |
| 3495 | |
| 3496 | if (new_vma->vm_file) |
| 3497 | fput(new_vma->vm_file); |
| 3498 | |
| 3499 | unlink_anon_vmas(new_vma); |
| 3500 | out_free_mempol: |
| 3501 | mpol_put(vma_policy(new_vma)); |
| 3502 | out_free_vma: |
| 3503 | vm_area_free(new_vma); |
| 3504 | out: |
| 3505 | return NULL; |
| 3506 | } |
| 3507 | |
| 3508 | /* |
| 3509 | * Return true if the calling process may expand its vm space by the passed |
| 3510 | * number of pages |
| 3511 | */ |
| 3512 | bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) |
| 3513 | { |
| 3514 | if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) |
| 3515 | return false; |
| 3516 | |
| 3517 | if (is_data_mapping(flags) && |
| 3518 | mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { |
| 3519 | /* Workaround for Valgrind */ |
| 3520 | if (rlimit(RLIMIT_DATA) == 0 && |
| 3521 | mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT) |
| 3522 | return true; |
| 3523 | |
| 3524 | pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n", |
| 3525 | current->comm, current->pid, |
| 3526 | (mm->data_vm + npages) << PAGE_SHIFT, |
| 3527 | rlimit(RLIMIT_DATA), |
| 3528 | ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data"); |
| 3529 | |
| 3530 | if (!ignore_rlimit_data) |
| 3531 | return false; |
| 3532 | } |
| 3533 | |
| 3534 | return true; |
| 3535 | } |
| 3536 | |
| 3537 | void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) |
| 3538 | { |
| 3539 | WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages); |
| 3540 | |
| 3541 | if (is_exec_mapping(flags)) |
| 3542 | mm->exec_vm += npages; |
| 3543 | else if (is_stack_mapping(flags)) |
| 3544 | mm->stack_vm += npages; |
| 3545 | else if (is_data_mapping(flags)) |
| 3546 | mm->data_vm += npages; |
| 3547 | } |
| 3548 | |
| 3549 | static vm_fault_t special_mapping_fault(struct vm_fault *vmf); |
| 3550 | |
| 3551 | /* |
| 3552 | * Having a close hook prevents vma merging regardless of flags. |
| 3553 | */ |
| 3554 | static void special_mapping_close(struct vm_area_struct *vma) |
| 3555 | { |
| 3556 | } |
| 3557 | |
| 3558 | static const char *special_mapping_name(struct vm_area_struct *vma) |
| 3559 | { |
| 3560 | return ((struct vm_special_mapping *)vma->vm_private_data)->name; |
| 3561 | } |
| 3562 | |
| 3563 | static int special_mapping_mremap(struct vm_area_struct *new_vma) |
| 3564 | { |
| 3565 | struct vm_special_mapping *sm = new_vma->vm_private_data; |
| 3566 | |
| 3567 | if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) |
| 3568 | return -EFAULT; |
| 3569 | |
| 3570 | if (sm->mremap) |
| 3571 | return sm->mremap(sm, new_vma); |
| 3572 | |
| 3573 | return 0; |
| 3574 | } |
| 3575 | |
| 3576 | static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) |
| 3577 | { |
| 3578 | /* |
| 3579 | * Forbid splitting special mappings - kernel has expectations over |
| 3580 | * the number of pages in mapping. Together with VM_DONTEXPAND |
| 3581 | * the size of vma should stay the same over the special mapping's |
| 3582 | * lifetime. |
| 3583 | */ |
| 3584 | return -EINVAL; |
| 3585 | } |
| 3586 | |
| 3587 | static const struct vm_operations_struct special_mapping_vmops = { |
| 3588 | .close = special_mapping_close, |
| 3589 | .fault = special_mapping_fault, |
| 3590 | .mremap = special_mapping_mremap, |
| 3591 | .name = special_mapping_name, |
| 3592 | /* vDSO code relies that VVAR can't be accessed remotely */ |
| 3593 | .access = NULL, |
| 3594 | .may_split = special_mapping_split, |
| 3595 | }; |
| 3596 | |
| 3597 | static const struct vm_operations_struct legacy_special_mapping_vmops = { |
| 3598 | .close = special_mapping_close, |
| 3599 | .fault = special_mapping_fault, |
| 3600 | }; |
| 3601 | |
| 3602 | static vm_fault_t special_mapping_fault(struct vm_fault *vmf) |
| 3603 | { |
| 3604 | struct vm_area_struct *vma = vmf->vma; |
| 3605 | pgoff_t pgoff; |
| 3606 | struct page **pages; |
| 3607 | |
| 3608 | if (vma->vm_ops == &legacy_special_mapping_vmops) { |
| 3609 | pages = vma->vm_private_data; |
| 3610 | } else { |
| 3611 | struct vm_special_mapping *sm = vma->vm_private_data; |
| 3612 | |
| 3613 | if (sm->fault) |
| 3614 | return sm->fault(sm, vmf->vma, vmf); |
| 3615 | |
| 3616 | pages = sm->pages; |
| 3617 | } |
| 3618 | |
| 3619 | for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) |
| 3620 | pgoff--; |
| 3621 | |
| 3622 | if (*pages) { |
| 3623 | struct page *page = *pages; |
| 3624 | get_page(page); |
| 3625 | vmf->page = page; |
| 3626 | return 0; |
| 3627 | } |
| 3628 | |
| 3629 | return VM_FAULT_SIGBUS; |
| 3630 | } |
| 3631 | |
| 3632 | static struct vm_area_struct *__install_special_mapping( |
| 3633 | struct mm_struct *mm, |
| 3634 | unsigned long addr, unsigned long len, |
| 3635 | unsigned long vm_flags, void *priv, |
| 3636 | const struct vm_operations_struct *ops) |
| 3637 | { |
| 3638 | int ret; |
| 3639 | struct vm_area_struct *vma; |
| 3640 | |
| 3641 | vma = vm_area_alloc(mm); |
| 3642 | if (unlikely(vma == NULL)) |
| 3643 | return ERR_PTR(-ENOMEM); |
| 3644 | |
| 3645 | vma_set_range(vma, addr, addr + len, 0); |
| 3646 | vm_flags_init(vma, (vm_flags | mm->def_flags | |
| 3647 | VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK); |
| 3648 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| 3649 | |
| 3650 | vma->vm_ops = ops; |
| 3651 | vma->vm_private_data = priv; |
| 3652 | |
| 3653 | ret = insert_vm_struct(mm, vma); |
| 3654 | if (ret) |
| 3655 | goto out; |
| 3656 | |
| 3657 | vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); |
| 3658 | |
| 3659 | perf_event_mmap(vma); |
| 3660 | |
| 3661 | return vma; |
| 3662 | |
| 3663 | out: |
| 3664 | vm_area_free(vma); |
| 3665 | return ERR_PTR(ret); |
| 3666 | } |
| 3667 | |
| 3668 | bool vma_is_special_mapping(const struct vm_area_struct *vma, |
| 3669 | const struct vm_special_mapping *sm) |
| 3670 | { |
| 3671 | return vma->vm_private_data == sm && |
| 3672 | (vma->vm_ops == &special_mapping_vmops || |
| 3673 | vma->vm_ops == &legacy_special_mapping_vmops); |
| 3674 | } |
| 3675 | |
| 3676 | /* |
| 3677 | * Called with mm->mmap_lock held for writing. |
| 3678 | * Insert a new vma covering the given region, with the given flags. |
| 3679 | * Its pages are supplied by the given array of struct page *. |
| 3680 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. |
| 3681 | * The region past the last page supplied will always produce SIGBUS. |
| 3682 | * The array pointer and the pages it points to are assumed to stay alive |
| 3683 | * for as long as this mapping might exist. |
| 3684 | */ |
| 3685 | struct vm_area_struct *_install_special_mapping( |
| 3686 | struct mm_struct *mm, |
| 3687 | unsigned long addr, unsigned long len, |
| 3688 | unsigned long vm_flags, const struct vm_special_mapping *spec) |
| 3689 | { |
| 3690 | return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, |
| 3691 | &special_mapping_vmops); |
| 3692 | } |
| 3693 | |
| 3694 | int install_special_mapping(struct mm_struct *mm, |
| 3695 | unsigned long addr, unsigned long len, |
| 3696 | unsigned long vm_flags, struct page **pages) |
| 3697 | { |
| 3698 | struct vm_area_struct *vma = __install_special_mapping( |
| 3699 | mm, addr, len, vm_flags, (void *)pages, |
| 3700 | &legacy_special_mapping_vmops); |
| 3701 | |
| 3702 | return PTR_ERR_OR_ZERO(vma); |
| 3703 | } |
| 3704 | |
| 3705 | static DEFINE_MUTEX(mm_all_locks_mutex); |
| 3706 | |
| 3707 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) |
| 3708 | { |
| 3709 | if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { |
| 3710 | /* |
| 3711 | * The LSB of head.next can't change from under us |
| 3712 | * because we hold the mm_all_locks_mutex. |
| 3713 | */ |
| 3714 | down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock); |
| 3715 | /* |
| 3716 | * We can safely modify head.next after taking the |
| 3717 | * anon_vma->root->rwsem. If some other vma in this mm shares |
| 3718 | * the same anon_vma we won't take it again. |
| 3719 | * |
| 3720 | * No need of atomic instructions here, head.next |
| 3721 | * can't change from under us thanks to the |
| 3722 | * anon_vma->root->rwsem. |
| 3723 | */ |
| 3724 | if (__test_and_set_bit(0, (unsigned long *) |
| 3725 | &anon_vma->root->rb_root.rb_root.rb_node)) |
| 3726 | BUG(); |
| 3727 | } |
| 3728 | } |
| 3729 | |
| 3730 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) |
| 3731 | { |
| 3732 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| 3733 | /* |
| 3734 | * AS_MM_ALL_LOCKS can't change from under us because |
| 3735 | * we hold the mm_all_locks_mutex. |
| 3736 | * |
| 3737 | * Operations on ->flags have to be atomic because |
| 3738 | * even if AS_MM_ALL_LOCKS is stable thanks to the |
| 3739 | * mm_all_locks_mutex, there may be other cpus |
| 3740 | * changing other bitflags in parallel to us. |
| 3741 | */ |
| 3742 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) |
| 3743 | BUG(); |
| 3744 | down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock); |
| 3745 | } |
| 3746 | } |
| 3747 | |
| 3748 | /* |
| 3749 | * This operation locks against the VM for all pte/vma/mm related |
| 3750 | * operations that could ever happen on a certain mm. This includes |
| 3751 | * vmtruncate, try_to_unmap, and all page faults. |
| 3752 | * |
| 3753 | * The caller must take the mmap_lock in write mode before calling |
| 3754 | * mm_take_all_locks(). The caller isn't allowed to release the |
| 3755 | * mmap_lock until mm_drop_all_locks() returns. |
| 3756 | * |
| 3757 | * mmap_lock in write mode is required in order to block all operations |
| 3758 | * that could modify pagetables and free pages without need of |
| 3759 | * altering the vma layout. It's also needed in write mode to avoid new |
| 3760 | * anon_vmas to be associated with existing vmas. |
| 3761 | * |
| 3762 | * A single task can't take more than one mm_take_all_locks() in a row |
| 3763 | * or it would deadlock. |
| 3764 | * |
| 3765 | * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in |
| 3766 | * mapping->flags avoid to take the same lock twice, if more than one |
| 3767 | * vma in this mm is backed by the same anon_vma or address_space. |
| 3768 | * |
| 3769 | * We take locks in following order, accordingly to comment at beginning |
| 3770 | * of mm/rmap.c: |
| 3771 | * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for |
| 3772 | * hugetlb mapping); |
| 3773 | * - all vmas marked locked |
| 3774 | * - all i_mmap_rwsem locks; |
| 3775 | * - all anon_vma->rwseml |
| 3776 | * |
| 3777 | * We can take all locks within these types randomly because the VM code |
| 3778 | * doesn't nest them and we protected from parallel mm_take_all_locks() by |
| 3779 | * mm_all_locks_mutex. |
| 3780 | * |
| 3781 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations |
| 3782 | * that may have to take thousand of locks. |
| 3783 | * |
| 3784 | * mm_take_all_locks() can fail if it's interrupted by signals. |
| 3785 | */ |
| 3786 | int mm_take_all_locks(struct mm_struct *mm) |
| 3787 | { |
| 3788 | struct vm_area_struct *vma; |
| 3789 | struct anon_vma_chain *avc; |
| 3790 | VMA_ITERATOR(vmi, mm, 0); |
| 3791 | |
| 3792 | mmap_assert_write_locked(mm); |
| 3793 | |
| 3794 | mutex_lock(&mm_all_locks_mutex); |
| 3795 | |
| 3796 | /* |
| 3797 | * vma_start_write() does not have a complement in mm_drop_all_locks() |
| 3798 | * because vma_start_write() is always asymmetrical; it marks a VMA as |
| 3799 | * being written to until mmap_write_unlock() or mmap_write_downgrade() |
| 3800 | * is reached. |
| 3801 | */ |
| 3802 | for_each_vma(vmi, vma) { |
| 3803 | if (signal_pending(current)) |
| 3804 | goto out_unlock; |
| 3805 | vma_start_write(vma); |
| 3806 | } |
| 3807 | |
| 3808 | vma_iter_init(&vmi, mm, 0); |
| 3809 | for_each_vma(vmi, vma) { |
| 3810 | if (signal_pending(current)) |
| 3811 | goto out_unlock; |
| 3812 | if (vma->vm_file && vma->vm_file->f_mapping && |
| 3813 | is_vm_hugetlb_page(vma)) |
| 3814 | vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| 3815 | } |
| 3816 | |
| 3817 | vma_iter_init(&vmi, mm, 0); |
| 3818 | for_each_vma(vmi, vma) { |
| 3819 | if (signal_pending(current)) |
| 3820 | goto out_unlock; |
| 3821 | if (vma->vm_file && vma->vm_file->f_mapping && |
| 3822 | !is_vm_hugetlb_page(vma)) |
| 3823 | vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| 3824 | } |
| 3825 | |
| 3826 | vma_iter_init(&vmi, mm, 0); |
| 3827 | for_each_vma(vmi, vma) { |
| 3828 | if (signal_pending(current)) |
| 3829 | goto out_unlock; |
| 3830 | if (vma->anon_vma) |
| 3831 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 3832 | vm_lock_anon_vma(mm, avc->anon_vma); |
| 3833 | } |
| 3834 | |
| 3835 | return 0; |
| 3836 | |
| 3837 | out_unlock: |
| 3838 | mm_drop_all_locks(mm); |
| 3839 | return -EINTR; |
| 3840 | } |
| 3841 | |
| 3842 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) |
| 3843 | { |
| 3844 | if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { |
| 3845 | /* |
| 3846 | * The LSB of head.next can't change to 0 from under |
| 3847 | * us because we hold the mm_all_locks_mutex. |
| 3848 | * |
| 3849 | * We must however clear the bitflag before unlocking |
| 3850 | * the vma so the users using the anon_vma->rb_root will |
| 3851 | * never see our bitflag. |
| 3852 | * |
| 3853 | * No need of atomic instructions here, head.next |
| 3854 | * can't change from under us until we release the |
| 3855 | * anon_vma->root->rwsem. |
| 3856 | */ |
| 3857 | if (!__test_and_clear_bit(0, (unsigned long *) |
| 3858 | &anon_vma->root->rb_root.rb_root.rb_node)) |
| 3859 | BUG(); |
| 3860 | anon_vma_unlock_write(anon_vma); |
| 3861 | } |
| 3862 | } |
| 3863 | |
| 3864 | static void vm_unlock_mapping(struct address_space *mapping) |
| 3865 | { |
| 3866 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| 3867 | /* |
| 3868 | * AS_MM_ALL_LOCKS can't change to 0 from under us |
| 3869 | * because we hold the mm_all_locks_mutex. |
| 3870 | */ |
| 3871 | i_mmap_unlock_write(mapping); |
| 3872 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, |
| 3873 | &mapping->flags)) |
| 3874 | BUG(); |
| 3875 | } |
| 3876 | } |
| 3877 | |
| 3878 | /* |
| 3879 | * The mmap_lock cannot be released by the caller until |
| 3880 | * mm_drop_all_locks() returns. |
| 3881 | */ |
| 3882 | void mm_drop_all_locks(struct mm_struct *mm) |
| 3883 | { |
| 3884 | struct vm_area_struct *vma; |
| 3885 | struct anon_vma_chain *avc; |
| 3886 | VMA_ITERATOR(vmi, mm, 0); |
| 3887 | |
| 3888 | mmap_assert_write_locked(mm); |
| 3889 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); |
| 3890 | |
| 3891 | for_each_vma(vmi, vma) { |
| 3892 | if (vma->anon_vma) |
| 3893 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 3894 | vm_unlock_anon_vma(avc->anon_vma); |
| 3895 | if (vma->vm_file && vma->vm_file->f_mapping) |
| 3896 | vm_unlock_mapping(vma->vm_file->f_mapping); |
| 3897 | } |
| 3898 | |
| 3899 | mutex_unlock(&mm_all_locks_mutex); |
| 3900 | } |
| 3901 | |
| 3902 | /* |
| 3903 | * initialise the percpu counter for VM |
| 3904 | */ |
| 3905 | void __init mmap_init(void) |
| 3906 | { |
| 3907 | int ret; |
| 3908 | |
| 3909 | ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); |
| 3910 | VM_BUG_ON(ret); |
| 3911 | } |
| 3912 | |
| 3913 | /* |
| 3914 | * Initialise sysctl_user_reserve_kbytes. |
| 3915 | * |
| 3916 | * This is intended to prevent a user from starting a single memory hogging |
| 3917 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
| 3918 | * mode. |
| 3919 | * |
| 3920 | * The default value is min(3% of free memory, 128MB) |
| 3921 | * 128MB is enough to recover with sshd/login, bash, and top/kill. |
| 3922 | */ |
| 3923 | static int init_user_reserve(void) |
| 3924 | { |
| 3925 | unsigned long free_kbytes; |
| 3926 | |
| 3927 | free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| 3928 | |
| 3929 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, SZ_128K); |
| 3930 | return 0; |
| 3931 | } |
| 3932 | subsys_initcall(init_user_reserve); |
| 3933 | |
| 3934 | /* |
| 3935 | * Initialise sysctl_admin_reserve_kbytes. |
| 3936 | * |
| 3937 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
| 3938 | * to log in and kill a memory hogging process. |
| 3939 | * |
| 3940 | * Systems with more than 256MB will reserve 8MB, enough to recover |
| 3941 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
| 3942 | * only reserve 3% of free pages by default. |
| 3943 | */ |
| 3944 | static int init_admin_reserve(void) |
| 3945 | { |
| 3946 | unsigned long free_kbytes; |
| 3947 | |
| 3948 | free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| 3949 | |
| 3950 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, SZ_8K); |
| 3951 | return 0; |
| 3952 | } |
| 3953 | subsys_initcall(init_admin_reserve); |
| 3954 | |
| 3955 | /* |
| 3956 | * Reinititalise user and admin reserves if memory is added or removed. |
| 3957 | * |
| 3958 | * The default user reserve max is 128MB, and the default max for the |
| 3959 | * admin reserve is 8MB. These are usually, but not always, enough to |
| 3960 | * enable recovery from a memory hogging process using login/sshd, a shell, |
| 3961 | * and tools like top. It may make sense to increase or even disable the |
| 3962 | * reserve depending on the existence of swap or variations in the recovery |
| 3963 | * tools. So, the admin may have changed them. |
| 3964 | * |
| 3965 | * If memory is added and the reserves have been eliminated or increased above |
| 3966 | * the default max, then we'll trust the admin. |
| 3967 | * |
| 3968 | * If memory is removed and there isn't enough free memory, then we |
| 3969 | * need to reset the reserves. |
| 3970 | * |
| 3971 | * Otherwise keep the reserve set by the admin. |
| 3972 | */ |
| 3973 | static int reserve_mem_notifier(struct notifier_block *nb, |
| 3974 | unsigned long action, void *data) |
| 3975 | { |
| 3976 | unsigned long tmp, free_kbytes; |
| 3977 | |
| 3978 | switch (action) { |
| 3979 | case MEM_ONLINE: |
| 3980 | /* Default max is 128MB. Leave alone if modified by operator. */ |
| 3981 | tmp = sysctl_user_reserve_kbytes; |
| 3982 | if (tmp > 0 && tmp < SZ_128K) |
| 3983 | init_user_reserve(); |
| 3984 | |
| 3985 | /* Default max is 8MB. Leave alone if modified by operator. */ |
| 3986 | tmp = sysctl_admin_reserve_kbytes; |
| 3987 | if (tmp > 0 && tmp < SZ_8K) |
| 3988 | init_admin_reserve(); |
| 3989 | |
| 3990 | break; |
| 3991 | case MEM_OFFLINE: |
| 3992 | free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| 3993 | |
| 3994 | if (sysctl_user_reserve_kbytes > free_kbytes) { |
| 3995 | init_user_reserve(); |
| 3996 | pr_info("vm.user_reserve_kbytes reset to %lu\n", |
| 3997 | sysctl_user_reserve_kbytes); |
| 3998 | } |
| 3999 | |
| 4000 | if (sysctl_admin_reserve_kbytes > free_kbytes) { |
| 4001 | init_admin_reserve(); |
| 4002 | pr_info("vm.admin_reserve_kbytes reset to %lu\n", |
| 4003 | sysctl_admin_reserve_kbytes); |
| 4004 | } |
| 4005 | break; |
| 4006 | default: |
| 4007 | break; |
| 4008 | } |
| 4009 | return NOTIFY_OK; |
| 4010 | } |
| 4011 | |
| 4012 | static int __meminit init_reserve_notifier(void) |
| 4013 | { |
| 4014 | if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI)) |
| 4015 | pr_err("Failed registering memory add/remove notifier for admin reserve\n"); |
| 4016 | |
| 4017 | return 0; |
| 4018 | } |
| 4019 | subsys_initcall(init_reserve_notifier); |