| 1 | /* |
| 2 | * mm/mmap.c |
| 3 | * |
| 4 | * Written by obz. |
| 5 | * |
| 6 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
| 7 | */ |
| 8 | |
| 9 | #include <linux/kernel.h> |
| 10 | #include <linux/slab.h> |
| 11 | #include <linux/backing-dev.h> |
| 12 | #include <linux/mm.h> |
| 13 | #include <linux/vmacache.h> |
| 14 | #include <linux/shm.h> |
| 15 | #include <linux/mman.h> |
| 16 | #include <linux/pagemap.h> |
| 17 | #include <linux/swap.h> |
| 18 | #include <linux/syscalls.h> |
| 19 | #include <linux/capability.h> |
| 20 | #include <linux/init.h> |
| 21 | #include <linux/file.h> |
| 22 | #include <linux/fs.h> |
| 23 | #include <linux/personality.h> |
| 24 | #include <linux/security.h> |
| 25 | #include <linux/hugetlb.h> |
| 26 | #include <linux/profile.h> |
| 27 | #include <linux/export.h> |
| 28 | #include <linux/mount.h> |
| 29 | #include <linux/mempolicy.h> |
| 30 | #include <linux/rmap.h> |
| 31 | #include <linux/mmu_notifier.h> |
| 32 | #include <linux/perf_event.h> |
| 33 | #include <linux/audit.h> |
| 34 | #include <linux/khugepaged.h> |
| 35 | #include <linux/uprobes.h> |
| 36 | #include <linux/rbtree_augmented.h> |
| 37 | #include <linux/sched/sysctl.h> |
| 38 | #include <linux/notifier.h> |
| 39 | #include <linux/memory.h> |
| 40 | |
| 41 | #include <asm/uaccess.h> |
| 42 | #include <asm/cacheflush.h> |
| 43 | #include <asm/tlb.h> |
| 44 | #include <asm/mmu_context.h> |
| 45 | |
| 46 | #include "internal.h" |
| 47 | #ifdef CONFIG_SDCARD_FS |
| 48 | #include "../fs/sdcardfs/sdcardfs.h" |
| 49 | #endif |
| 50 | |
| 51 | #ifndef arch_mmap_check |
| 52 | #define arch_mmap_check(addr, len, flags) (0) |
| 53 | #endif |
| 54 | |
| 55 | #ifndef arch_rebalance_pgtables |
| 56 | #define arch_rebalance_pgtables(addr, len) (addr) |
| 57 | #endif |
| 58 | |
| 59 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS |
| 60 | const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; |
| 61 | const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; |
| 62 | int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; |
| 63 | #endif |
| 64 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 65 | const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; |
| 66 | const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; |
| 67 | int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; |
| 68 | #endif |
| 69 | |
| 70 | |
| 71 | static void unmap_region(struct mm_struct *mm, |
| 72 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
| 73 | unsigned long start, unsigned long end); |
| 74 | |
| 75 | /* description of effects of mapping type and prot in current implementation. |
| 76 | * this is due to the limited x86 page protection hardware. The expected |
| 77 | * behavior is in parens: |
| 78 | * |
| 79 | * map_type prot |
| 80 | * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC |
| 81 | * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes |
| 82 | * w: (no) no w: (no) no w: (yes) yes w: (no) no |
| 83 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes |
| 84 | * |
| 85 | * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes |
| 86 | * w: (no) no w: (no) no w: (copy) copy w: (no) no |
| 87 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes |
| 88 | * |
| 89 | */ |
| 90 | pgprot_t protection_map[16] = { |
| 91 | __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, |
| 92 | __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 |
| 93 | }; |
| 94 | |
| 95 | pgprot_t vm_get_page_prot(unsigned long vm_flags) |
| 96 | { |
| 97 | return __pgprot(pgprot_val(protection_map[vm_flags & |
| 98 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | |
| 99 | pgprot_val(arch_vm_get_page_prot(vm_flags))); |
| 100 | } |
| 101 | EXPORT_SYMBOL(vm_get_page_prot); |
| 102 | |
| 103 | int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ |
| 104 | int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ |
| 105 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; |
| 106 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ |
| 107 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ |
| 108 | /* |
| 109 | * Make sure vm_committed_as in one cacheline and not cacheline shared with |
| 110 | * other variables. It can be updated by several CPUs frequently. |
| 111 | */ |
| 112 | struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; |
| 113 | |
| 114 | /* |
| 115 | * The global memory commitment made in the system can be a metric |
| 116 | * that can be used to drive ballooning decisions when Linux is hosted |
| 117 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically |
| 118 | * balancing memory across competing virtual machines that are hosted. |
| 119 | * Several metrics drive this policy engine including the guest reported |
| 120 | * memory commitment. |
| 121 | */ |
| 122 | unsigned long vm_memory_committed(void) |
| 123 | { |
| 124 | return percpu_counter_read_positive(&vm_committed_as); |
| 125 | } |
| 126 | EXPORT_SYMBOL_GPL(vm_memory_committed); |
| 127 | |
| 128 | /* |
| 129 | * Check that a process has enough memory to allocate a new virtual |
| 130 | * mapping. 0 means there is enough memory for the allocation to |
| 131 | * succeed and -ENOMEM implies there is not. |
| 132 | * |
| 133 | * We currently support three overcommit policies, which are set via the |
| 134 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting |
| 135 | * |
| 136 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. |
| 137 | * Additional code 2002 Jul 20 by Robert Love. |
| 138 | * |
| 139 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. |
| 140 | * |
| 141 | * Note this is a helper function intended to be used by LSMs which |
| 142 | * wish to use this logic. |
| 143 | */ |
| 144 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) |
| 145 | { |
| 146 | long free, allowed, reserve; |
| 147 | |
| 148 | vm_acct_memory(pages); |
| 149 | |
| 150 | /* |
| 151 | * Sometimes we want to use more memory than we have |
| 152 | */ |
| 153 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) |
| 154 | return 0; |
| 155 | |
| 156 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { |
| 157 | free = global_page_state(NR_FREE_PAGES); |
| 158 | free += global_page_state(NR_FILE_PAGES); |
| 159 | |
| 160 | /* |
| 161 | * shmem pages shouldn't be counted as free in this |
| 162 | * case, they can't be purged, only swapped out, and |
| 163 | * that won't affect the overall amount of available |
| 164 | * memory in the system. |
| 165 | */ |
| 166 | free -= global_page_state(NR_SHMEM); |
| 167 | |
| 168 | free += get_nr_swap_pages(); |
| 169 | |
| 170 | /* |
| 171 | * Any slabs which are created with the |
| 172 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents |
| 173 | * which are reclaimable, under pressure. The dentry |
| 174 | * cache and most inode caches should fall into this |
| 175 | */ |
| 176 | free += global_page_state(NR_SLAB_RECLAIMABLE); |
| 177 | |
| 178 | /* |
| 179 | * Leave reserved pages. The pages are not for anonymous pages. |
| 180 | */ |
| 181 | if (free <= totalreserve_pages) |
| 182 | goto error; |
| 183 | else |
| 184 | free -= totalreserve_pages; |
| 185 | |
| 186 | /* |
| 187 | * Reserve some for root |
| 188 | */ |
| 189 | if (!cap_sys_admin) |
| 190 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
| 191 | |
| 192 | if (free > pages) |
| 193 | return 0; |
| 194 | |
| 195 | goto error; |
| 196 | } |
| 197 | |
| 198 | allowed = (totalram_pages - hugetlb_total_pages()) |
| 199 | * sysctl_overcommit_ratio / 100; |
| 200 | /* |
| 201 | * Reserve some for root |
| 202 | */ |
| 203 | if (!cap_sys_admin) |
| 204 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
| 205 | allowed += total_swap_pages; |
| 206 | |
| 207 | /* |
| 208 | * Don't let a single process grow so big a user can't recover |
| 209 | */ |
| 210 | if (mm) { |
| 211 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); |
| 212 | allowed -= min_t(long, mm->total_vm / 32, reserve); |
| 213 | } |
| 214 | |
| 215 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) |
| 216 | return 0; |
| 217 | error: |
| 218 | vm_unacct_memory(pages); |
| 219 | |
| 220 | return -ENOMEM; |
| 221 | } |
| 222 | |
| 223 | /* |
| 224 | * Requires inode->i_mapping->i_mmap_mutex |
| 225 | */ |
| 226 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, |
| 227 | struct file *file, struct address_space *mapping) |
| 228 | { |
| 229 | if (vma->vm_flags & VM_DENYWRITE) |
| 230 | atomic_inc(&file_inode(file)->i_writecount); |
| 231 | if (vma->vm_flags & VM_SHARED) |
| 232 | mapping_unmap_writable(mapping); |
| 233 | |
| 234 | flush_dcache_mmap_lock(mapping); |
| 235 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
| 236 | list_del_init(&vma->shared.nonlinear); |
| 237 | else |
| 238 | vma_interval_tree_remove(vma, &mapping->i_mmap); |
| 239 | flush_dcache_mmap_unlock(mapping); |
| 240 | } |
| 241 | |
| 242 | /* |
| 243 | * Unlink a file-based vm structure from its interval tree, to hide |
| 244 | * vma from rmap and vmtruncate before freeing its page tables. |
| 245 | */ |
| 246 | void unlink_file_vma(struct vm_area_struct *vma) |
| 247 | { |
| 248 | struct file *file = vma->vm_file; |
| 249 | |
| 250 | if (file) { |
| 251 | struct address_space *mapping = file->f_mapping; |
| 252 | mutex_lock(&mapping->i_mmap_mutex); |
| 253 | __remove_shared_vm_struct(vma, file, mapping); |
| 254 | mutex_unlock(&mapping->i_mmap_mutex); |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | /* |
| 259 | * Close a vm structure and free it, returning the next. |
| 260 | */ |
| 261 | static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) |
| 262 | { |
| 263 | struct vm_area_struct *next = vma->vm_next; |
| 264 | |
| 265 | might_sleep(); |
| 266 | if (vma->vm_ops && vma->vm_ops->close) |
| 267 | vma->vm_ops->close(vma); |
| 268 | if (vma->vm_file) |
| 269 | fput(vma->vm_file); |
| 270 | mpol_put(vma_policy(vma)); |
| 271 | kmem_cache_free(vm_area_cachep, vma); |
| 272 | return next; |
| 273 | } |
| 274 | |
| 275 | static unsigned long do_brk(unsigned long addr, unsigned long len); |
| 276 | |
| 277 | SYSCALL_DEFINE1(brk, unsigned long, brk) |
| 278 | { |
| 279 | unsigned long rlim, retval; |
| 280 | unsigned long newbrk, oldbrk; |
| 281 | struct mm_struct *mm = current->mm; |
| 282 | struct vm_area_struct *next; |
| 283 | unsigned long min_brk; |
| 284 | bool populate; |
| 285 | |
| 286 | down_write(&mm->mmap_sem); |
| 287 | |
| 288 | #ifdef CONFIG_COMPAT_BRK |
| 289 | /* |
| 290 | * CONFIG_COMPAT_BRK can still be overridden by setting |
| 291 | * randomize_va_space to 2, which will still cause mm->start_brk |
| 292 | * to be arbitrarily shifted |
| 293 | */ |
| 294 | if (current->brk_randomized) |
| 295 | min_brk = mm->start_brk; |
| 296 | else |
| 297 | min_brk = mm->end_data; |
| 298 | #else |
| 299 | min_brk = mm->start_brk; |
| 300 | #endif |
| 301 | if (brk < min_brk) |
| 302 | goto out; |
| 303 | |
| 304 | /* |
| 305 | * Check against rlimit here. If this check is done later after the test |
| 306 | * of oldbrk with newbrk then it can escape the test and let the data |
| 307 | * segment grow beyond its set limit the in case where the limit is |
| 308 | * not page aligned -Ram Gupta |
| 309 | */ |
| 310 | rlim = rlimit(RLIMIT_DATA); |
| 311 | if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + |
| 312 | (mm->end_data - mm->start_data) > rlim) |
| 313 | goto out; |
| 314 | |
| 315 | newbrk = PAGE_ALIGN(brk); |
| 316 | oldbrk = PAGE_ALIGN(mm->brk); |
| 317 | if (oldbrk == newbrk) |
| 318 | goto set_brk; |
| 319 | |
| 320 | /* Always allow shrinking brk. */ |
| 321 | if (brk <= mm->brk) { |
| 322 | if (!do_munmap(mm, newbrk, oldbrk-newbrk)) |
| 323 | goto set_brk; |
| 324 | goto out; |
| 325 | } |
| 326 | |
| 327 | /* Check against existing mmap mappings. */ |
| 328 | next = find_vma(mm, oldbrk); |
| 329 | if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) |
| 330 | goto out; |
| 331 | |
| 332 | /* Ok, looks good - let it rip. */ |
| 333 | if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) |
| 334 | goto out; |
| 335 | |
| 336 | set_brk: |
| 337 | mm->brk = brk; |
| 338 | populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; |
| 339 | up_write(&mm->mmap_sem); |
| 340 | if (populate) |
| 341 | mm_populate(oldbrk, newbrk - oldbrk); |
| 342 | return brk; |
| 343 | |
| 344 | out: |
| 345 | retval = mm->brk; |
| 346 | up_write(&mm->mmap_sem); |
| 347 | return retval; |
| 348 | } |
| 349 | |
| 350 | static long vma_compute_subtree_gap(struct vm_area_struct *vma) |
| 351 | { |
| 352 | unsigned long max, prev_end, subtree_gap; |
| 353 | |
| 354 | /* |
| 355 | * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we |
| 356 | * allow two stack_guard_gaps between them here, and when choosing |
| 357 | * an unmapped area; whereas when expanding we only require one. |
| 358 | * That's a little inconsistent, but keeps the code here simpler. |
| 359 | */ |
| 360 | max = vm_start_gap(vma); |
| 361 | if (vma->vm_prev) { |
| 362 | prev_end = vm_end_gap(vma->vm_prev); |
| 363 | if (max > prev_end) |
| 364 | max -= prev_end; |
| 365 | else |
| 366 | max = 0; |
| 367 | } |
| 368 | if (vma->vm_rb.rb_left) { |
| 369 | subtree_gap = rb_entry(vma->vm_rb.rb_left, |
| 370 | struct vm_area_struct, vm_rb)->rb_subtree_gap; |
| 371 | if (subtree_gap > max) |
| 372 | max = subtree_gap; |
| 373 | } |
| 374 | if (vma->vm_rb.rb_right) { |
| 375 | subtree_gap = rb_entry(vma->vm_rb.rb_right, |
| 376 | struct vm_area_struct, vm_rb)->rb_subtree_gap; |
| 377 | if (subtree_gap > max) |
| 378 | max = subtree_gap; |
| 379 | } |
| 380 | return max; |
| 381 | } |
| 382 | |
| 383 | #ifdef CONFIG_DEBUG_VM_RB |
| 384 | static int browse_rb(struct rb_root *root) |
| 385 | { |
| 386 | int i = 0, j, bug = 0; |
| 387 | struct rb_node *nd, *pn = NULL; |
| 388 | unsigned long prev = 0, pend = 0; |
| 389 | |
| 390 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { |
| 391 | struct vm_area_struct *vma; |
| 392 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); |
| 393 | if (vma->vm_start < prev) { |
| 394 | printk("vm_start %lx prev %lx\n", vma->vm_start, prev); |
| 395 | bug = 1; |
| 396 | } |
| 397 | if (vma->vm_start < pend) { |
| 398 | printk("vm_start %lx pend %lx\n", vma->vm_start, pend); |
| 399 | bug = 1; |
| 400 | } |
| 401 | if (vma->vm_start > vma->vm_end) { |
| 402 | printk("vm_end %lx < vm_start %lx\n", |
| 403 | vma->vm_end, vma->vm_start); |
| 404 | bug = 1; |
| 405 | } |
| 406 | if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { |
| 407 | printk("free gap %lx, correct %lx\n", |
| 408 | vma->rb_subtree_gap, |
| 409 | vma_compute_subtree_gap(vma)); |
| 410 | bug = 1; |
| 411 | } |
| 412 | i++; |
| 413 | pn = nd; |
| 414 | prev = vma->vm_start; |
| 415 | pend = vma->vm_end; |
| 416 | } |
| 417 | j = 0; |
| 418 | for (nd = pn; nd; nd = rb_prev(nd)) |
| 419 | j++; |
| 420 | if (i != j) { |
| 421 | printk("backwards %d, forwards %d\n", j, i); |
| 422 | bug = 1; |
| 423 | } |
| 424 | return bug ? -1 : i; |
| 425 | } |
| 426 | |
| 427 | static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) |
| 428 | { |
| 429 | struct rb_node *nd; |
| 430 | |
| 431 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { |
| 432 | struct vm_area_struct *vma; |
| 433 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); |
| 434 | BUG_ON(vma != ignore && |
| 435 | vma->rb_subtree_gap != vma_compute_subtree_gap(vma)); |
| 436 | } |
| 437 | } |
| 438 | |
| 439 | void validate_mm(struct mm_struct *mm) |
| 440 | { |
| 441 | int bug = 0; |
| 442 | int i = 0; |
| 443 | unsigned long highest_address = 0; |
| 444 | struct vm_area_struct *vma = mm->mmap; |
| 445 | while (vma) { |
| 446 | struct anon_vma_chain *avc; |
| 447 | vma_lock_anon_vma(vma); |
| 448 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 449 | anon_vma_interval_tree_verify(avc); |
| 450 | vma_unlock_anon_vma(vma); |
| 451 | highest_address = vm_end_gap(vma); |
| 452 | vma = vma->vm_next; |
| 453 | i++; |
| 454 | } |
| 455 | if (i != mm->map_count) { |
| 456 | printk("map_count %d vm_next %d\n", mm->map_count, i); |
| 457 | bug = 1; |
| 458 | } |
| 459 | if (highest_address != mm->highest_vm_end) { |
| 460 | printk("mm->highest_vm_end %lx, found %lx\n", |
| 461 | mm->highest_vm_end, highest_address); |
| 462 | bug = 1; |
| 463 | } |
| 464 | i = browse_rb(&mm->mm_rb); |
| 465 | if (i != mm->map_count) { |
| 466 | printk("map_count %d rb %d\n", mm->map_count, i); |
| 467 | bug = 1; |
| 468 | } |
| 469 | BUG_ON(bug); |
| 470 | } |
| 471 | #else |
| 472 | #define validate_mm_rb(root, ignore) do { } while (0) |
| 473 | #define validate_mm(mm) do { } while (0) |
| 474 | #endif |
| 475 | |
| 476 | RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, |
| 477 | unsigned long, rb_subtree_gap, vma_compute_subtree_gap) |
| 478 | |
| 479 | /* |
| 480 | * Update augmented rbtree rb_subtree_gap values after vma->vm_start or |
| 481 | * vma->vm_prev->vm_end values changed, without modifying the vma's position |
| 482 | * in the rbtree. |
| 483 | */ |
| 484 | static void vma_gap_update(struct vm_area_struct *vma) |
| 485 | { |
| 486 | /* |
| 487 | * As it turns out, RB_DECLARE_CALLBACKS() already created a callback |
| 488 | * function that does exacltly what we want. |
| 489 | */ |
| 490 | vma_gap_callbacks_propagate(&vma->vm_rb, NULL); |
| 491 | } |
| 492 | |
| 493 | static inline void vma_rb_insert(struct vm_area_struct *vma, |
| 494 | struct rb_root *root) |
| 495 | { |
| 496 | /* All rb_subtree_gap values must be consistent prior to insertion */ |
| 497 | validate_mm_rb(root, NULL); |
| 498 | |
| 499 | rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); |
| 500 | } |
| 501 | |
| 502 | static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) |
| 503 | { |
| 504 | /* |
| 505 | * All rb_subtree_gap values must be consistent prior to erase, |
| 506 | * with the possible exception of the vma being erased. |
| 507 | */ |
| 508 | validate_mm_rb(root, vma); |
| 509 | |
| 510 | /* |
| 511 | * Note rb_erase_augmented is a fairly large inline function, |
| 512 | * so make sure we instantiate it only once with our desired |
| 513 | * augmented rbtree callbacks. |
| 514 | */ |
| 515 | rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); |
| 516 | } |
| 517 | |
| 518 | /* |
| 519 | * vma has some anon_vma assigned, and is already inserted on that |
| 520 | * anon_vma's interval trees. |
| 521 | * |
| 522 | * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the |
| 523 | * vma must be removed from the anon_vma's interval trees using |
| 524 | * anon_vma_interval_tree_pre_update_vma(). |
| 525 | * |
| 526 | * After the update, the vma will be reinserted using |
| 527 | * anon_vma_interval_tree_post_update_vma(). |
| 528 | * |
| 529 | * The entire update must be protected by exclusive mmap_sem and by |
| 530 | * the root anon_vma's mutex. |
| 531 | */ |
| 532 | static inline void |
| 533 | anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) |
| 534 | { |
| 535 | struct anon_vma_chain *avc; |
| 536 | |
| 537 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 538 | anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); |
| 539 | } |
| 540 | |
| 541 | static inline void |
| 542 | anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) |
| 543 | { |
| 544 | struct anon_vma_chain *avc; |
| 545 | |
| 546 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 547 | anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); |
| 548 | } |
| 549 | |
| 550 | static int find_vma_links(struct mm_struct *mm, unsigned long addr, |
| 551 | unsigned long end, struct vm_area_struct **pprev, |
| 552 | struct rb_node ***rb_link, struct rb_node **rb_parent) |
| 553 | { |
| 554 | struct rb_node **__rb_link, *__rb_parent, *rb_prev; |
| 555 | |
| 556 | __rb_link = &mm->mm_rb.rb_node; |
| 557 | rb_prev = __rb_parent = NULL; |
| 558 | |
| 559 | while (*__rb_link) { |
| 560 | struct vm_area_struct *vma_tmp; |
| 561 | |
| 562 | __rb_parent = *__rb_link; |
| 563 | vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); |
| 564 | |
| 565 | if (vma_tmp->vm_end > addr) { |
| 566 | /* Fail if an existing vma overlaps the area */ |
| 567 | if (vma_tmp->vm_start < end) |
| 568 | return -ENOMEM; |
| 569 | __rb_link = &__rb_parent->rb_left; |
| 570 | } else { |
| 571 | rb_prev = __rb_parent; |
| 572 | __rb_link = &__rb_parent->rb_right; |
| 573 | } |
| 574 | } |
| 575 | |
| 576 | *pprev = NULL; |
| 577 | if (rb_prev) |
| 578 | *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); |
| 579 | *rb_link = __rb_link; |
| 580 | *rb_parent = __rb_parent; |
| 581 | return 0; |
| 582 | } |
| 583 | |
| 584 | static unsigned long count_vma_pages_range(struct mm_struct *mm, |
| 585 | unsigned long addr, unsigned long end) |
| 586 | { |
| 587 | unsigned long nr_pages = 0; |
| 588 | struct vm_area_struct *vma; |
| 589 | |
| 590 | /* Find first overlaping mapping */ |
| 591 | vma = find_vma_intersection(mm, addr, end); |
| 592 | if (!vma) |
| 593 | return 0; |
| 594 | |
| 595 | nr_pages = (min(end, vma->vm_end) - |
| 596 | max(addr, vma->vm_start)) >> PAGE_SHIFT; |
| 597 | |
| 598 | /* Iterate over the rest of the overlaps */ |
| 599 | for (vma = vma->vm_next; vma; vma = vma->vm_next) { |
| 600 | unsigned long overlap_len; |
| 601 | |
| 602 | if (vma->vm_start > end) |
| 603 | break; |
| 604 | |
| 605 | overlap_len = min(end, vma->vm_end) - vma->vm_start; |
| 606 | nr_pages += overlap_len >> PAGE_SHIFT; |
| 607 | } |
| 608 | |
| 609 | return nr_pages; |
| 610 | } |
| 611 | |
| 612 | void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, |
| 613 | struct rb_node **rb_link, struct rb_node *rb_parent) |
| 614 | { |
| 615 | /* Update tracking information for the gap following the new vma. */ |
| 616 | if (vma->vm_next) |
| 617 | vma_gap_update(vma->vm_next); |
| 618 | else |
| 619 | mm->highest_vm_end = vm_end_gap(vma); |
| 620 | |
| 621 | /* |
| 622 | * vma->vm_prev wasn't known when we followed the rbtree to find the |
| 623 | * correct insertion point for that vma. As a result, we could not |
| 624 | * update the vma vm_rb parents rb_subtree_gap values on the way down. |
| 625 | * So, we first insert the vma with a zero rb_subtree_gap value |
| 626 | * (to be consistent with what we did on the way down), and then |
| 627 | * immediately update the gap to the correct value. Finally we |
| 628 | * rebalance the rbtree after all augmented values have been set. |
| 629 | */ |
| 630 | rb_link_node(&vma->vm_rb, rb_parent, rb_link); |
| 631 | vma->rb_subtree_gap = 0; |
| 632 | vma_gap_update(vma); |
| 633 | vma_rb_insert(vma, &mm->mm_rb); |
| 634 | } |
| 635 | |
| 636 | static void __vma_link_file(struct vm_area_struct *vma) |
| 637 | { |
| 638 | struct file *file; |
| 639 | |
| 640 | file = vma->vm_file; |
| 641 | if (file) { |
| 642 | struct address_space *mapping = file->f_mapping; |
| 643 | |
| 644 | if (vma->vm_flags & VM_DENYWRITE) |
| 645 | atomic_dec(&file_inode(file)->i_writecount); |
| 646 | if (vma->vm_flags & VM_SHARED) |
| 647 | atomic_inc(&mapping->i_mmap_writable); |
| 648 | |
| 649 | flush_dcache_mmap_lock(mapping); |
| 650 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
| 651 | vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); |
| 652 | else |
| 653 | vma_interval_tree_insert(vma, &mapping->i_mmap); |
| 654 | flush_dcache_mmap_unlock(mapping); |
| 655 | } |
| 656 | } |
| 657 | |
| 658 | static void |
| 659 | __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, |
| 660 | struct vm_area_struct *prev, struct rb_node **rb_link, |
| 661 | struct rb_node *rb_parent) |
| 662 | { |
| 663 | __vma_link_list(mm, vma, prev, rb_parent); |
| 664 | __vma_link_rb(mm, vma, rb_link, rb_parent); |
| 665 | } |
| 666 | |
| 667 | static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, |
| 668 | struct vm_area_struct *prev, struct rb_node **rb_link, |
| 669 | struct rb_node *rb_parent) |
| 670 | { |
| 671 | struct address_space *mapping = NULL; |
| 672 | |
| 673 | if (vma->vm_file) |
| 674 | mapping = vma->vm_file->f_mapping; |
| 675 | |
| 676 | if (mapping) |
| 677 | mutex_lock(&mapping->i_mmap_mutex); |
| 678 | |
| 679 | __vma_link(mm, vma, prev, rb_link, rb_parent); |
| 680 | __vma_link_file(vma); |
| 681 | |
| 682 | if (mapping) |
| 683 | mutex_unlock(&mapping->i_mmap_mutex); |
| 684 | |
| 685 | mm->map_count++; |
| 686 | validate_mm(mm); |
| 687 | } |
| 688 | |
| 689 | /* |
| 690 | * Helper for vma_adjust() in the split_vma insert case: insert a vma into the |
| 691 | * mm's list and rbtree. It has already been inserted into the interval tree. |
| 692 | */ |
| 693 | static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| 694 | { |
| 695 | struct vm_area_struct *prev; |
| 696 | struct rb_node **rb_link, *rb_parent; |
| 697 | |
| 698 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, |
| 699 | &prev, &rb_link, &rb_parent)) |
| 700 | BUG(); |
| 701 | __vma_link(mm, vma, prev, rb_link, rb_parent); |
| 702 | mm->map_count++; |
| 703 | } |
| 704 | |
| 705 | static inline void |
| 706 | __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, |
| 707 | struct vm_area_struct *prev) |
| 708 | { |
| 709 | struct vm_area_struct *next; |
| 710 | |
| 711 | vma_rb_erase(vma, &mm->mm_rb); |
| 712 | prev->vm_next = next = vma->vm_next; |
| 713 | if (next) |
| 714 | next->vm_prev = prev; |
| 715 | |
| 716 | /* Kill the cache */ |
| 717 | vmacache_invalidate(mm); |
| 718 | } |
| 719 | |
| 720 | /* |
| 721 | * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that |
| 722 | * is already present in an i_mmap tree without adjusting the tree. |
| 723 | * The following helper function should be used when such adjustments |
| 724 | * are necessary. The "insert" vma (if any) is to be inserted |
| 725 | * before we drop the necessary locks. |
| 726 | */ |
| 727 | int vma_adjust(struct vm_area_struct *vma, unsigned long start, |
| 728 | unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) |
| 729 | { |
| 730 | struct mm_struct *mm = vma->vm_mm; |
| 731 | struct vm_area_struct *next = vma->vm_next; |
| 732 | struct vm_area_struct *importer = NULL; |
| 733 | struct address_space *mapping = NULL; |
| 734 | struct rb_root *root = NULL; |
| 735 | struct anon_vma *anon_vma = NULL; |
| 736 | struct file *file = vma->vm_file; |
| 737 | bool start_changed = false, end_changed = false; |
| 738 | long adjust_next = 0; |
| 739 | int remove_next = 0; |
| 740 | |
| 741 | if (next && !insert) { |
| 742 | struct vm_area_struct *exporter = NULL; |
| 743 | |
| 744 | if (end >= next->vm_end) { |
| 745 | /* |
| 746 | * vma expands, overlapping all the next, and |
| 747 | * perhaps the one after too (mprotect case 6). |
| 748 | */ |
| 749 | again: remove_next = 1 + (end > next->vm_end); |
| 750 | end = next->vm_end; |
| 751 | exporter = next; |
| 752 | importer = vma; |
| 753 | } else if (end > next->vm_start) { |
| 754 | /* |
| 755 | * vma expands, overlapping part of the next: |
| 756 | * mprotect case 5 shifting the boundary up. |
| 757 | */ |
| 758 | adjust_next = (end - next->vm_start) >> PAGE_SHIFT; |
| 759 | exporter = next; |
| 760 | importer = vma; |
| 761 | } else if (end < vma->vm_end) { |
| 762 | /* |
| 763 | * vma shrinks, and !insert tells it's not |
| 764 | * split_vma inserting another: so it must be |
| 765 | * mprotect case 4 shifting the boundary down. |
| 766 | */ |
| 767 | adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); |
| 768 | exporter = vma; |
| 769 | importer = next; |
| 770 | } |
| 771 | |
| 772 | /* |
| 773 | * Easily overlooked: when mprotect shifts the boundary, |
| 774 | * make sure the expanding vma has anon_vma set if the |
| 775 | * shrinking vma had, to cover any anon pages imported. |
| 776 | */ |
| 777 | if (exporter && exporter->anon_vma && !importer->anon_vma) { |
| 778 | if (anon_vma_clone(importer, exporter)) |
| 779 | return -ENOMEM; |
| 780 | importer->anon_vma = exporter->anon_vma; |
| 781 | } |
| 782 | } |
| 783 | |
| 784 | if (file) { |
| 785 | mapping = file->f_mapping; |
| 786 | if (!(vma->vm_flags & VM_NONLINEAR)) { |
| 787 | root = &mapping->i_mmap; |
| 788 | uprobe_munmap(vma, vma->vm_start, vma->vm_end); |
| 789 | |
| 790 | if (adjust_next) |
| 791 | uprobe_munmap(next, next->vm_start, |
| 792 | next->vm_end); |
| 793 | } |
| 794 | |
| 795 | mutex_lock(&mapping->i_mmap_mutex); |
| 796 | if (insert) { |
| 797 | /* |
| 798 | * Put into interval tree now, so instantiated pages |
| 799 | * are visible to arm/parisc __flush_dcache_page |
| 800 | * throughout; but we cannot insert into address |
| 801 | * space until vma start or end is updated. |
| 802 | */ |
| 803 | __vma_link_file(insert); |
| 804 | } |
| 805 | } |
| 806 | |
| 807 | vma_adjust_trans_huge(vma, start, end, adjust_next); |
| 808 | |
| 809 | anon_vma = vma->anon_vma; |
| 810 | if (!anon_vma && adjust_next) |
| 811 | anon_vma = next->anon_vma; |
| 812 | if (anon_vma) { |
| 813 | VM_BUG_ON(adjust_next && next->anon_vma && |
| 814 | anon_vma != next->anon_vma); |
| 815 | anon_vma_lock_write(anon_vma); |
| 816 | anon_vma_interval_tree_pre_update_vma(vma); |
| 817 | if (adjust_next) |
| 818 | anon_vma_interval_tree_pre_update_vma(next); |
| 819 | } |
| 820 | |
| 821 | if (root) { |
| 822 | flush_dcache_mmap_lock(mapping); |
| 823 | vma_interval_tree_remove(vma, root); |
| 824 | if (adjust_next) |
| 825 | vma_interval_tree_remove(next, root); |
| 826 | } |
| 827 | |
| 828 | if (start != vma->vm_start) { |
| 829 | vma->vm_start = start; |
| 830 | start_changed = true; |
| 831 | } |
| 832 | if (end != vma->vm_end) { |
| 833 | vma->vm_end = end; |
| 834 | end_changed = true; |
| 835 | } |
| 836 | vma->vm_pgoff = pgoff; |
| 837 | if (adjust_next) { |
| 838 | next->vm_start += adjust_next << PAGE_SHIFT; |
| 839 | next->vm_pgoff += adjust_next; |
| 840 | } |
| 841 | |
| 842 | if (root) { |
| 843 | if (adjust_next) |
| 844 | vma_interval_tree_insert(next, root); |
| 845 | vma_interval_tree_insert(vma, root); |
| 846 | flush_dcache_mmap_unlock(mapping); |
| 847 | } |
| 848 | |
| 849 | if (remove_next) { |
| 850 | /* |
| 851 | * vma_merge has merged next into vma, and needs |
| 852 | * us to remove next before dropping the locks. |
| 853 | */ |
| 854 | __vma_unlink(mm, next, vma); |
| 855 | if (file) |
| 856 | __remove_shared_vm_struct(next, file, mapping); |
| 857 | } else if (insert) { |
| 858 | /* |
| 859 | * split_vma has split insert from vma, and needs |
| 860 | * us to insert it before dropping the locks |
| 861 | * (it may either follow vma or precede it). |
| 862 | */ |
| 863 | __insert_vm_struct(mm, insert); |
| 864 | } else { |
| 865 | if (start_changed) |
| 866 | vma_gap_update(vma); |
| 867 | if (end_changed) { |
| 868 | if (!next) |
| 869 | mm->highest_vm_end = vm_end_gap(vma); |
| 870 | else if (!adjust_next) |
| 871 | vma_gap_update(next); |
| 872 | } |
| 873 | } |
| 874 | |
| 875 | if (anon_vma) { |
| 876 | anon_vma_interval_tree_post_update_vma(vma); |
| 877 | if (adjust_next) |
| 878 | anon_vma_interval_tree_post_update_vma(next); |
| 879 | anon_vma_unlock_write(anon_vma); |
| 880 | } |
| 881 | if (mapping) |
| 882 | mutex_unlock(&mapping->i_mmap_mutex); |
| 883 | |
| 884 | if (root) { |
| 885 | uprobe_mmap(vma); |
| 886 | |
| 887 | if (adjust_next) |
| 888 | uprobe_mmap(next); |
| 889 | } |
| 890 | |
| 891 | if (remove_next) { |
| 892 | if (file) { |
| 893 | uprobe_munmap(next, next->vm_start, next->vm_end); |
| 894 | fput(file); |
| 895 | } |
| 896 | if (next->anon_vma) |
| 897 | anon_vma_merge(vma, next); |
| 898 | mm->map_count--; |
| 899 | mpol_put(vma_policy(next)); |
| 900 | kmem_cache_free(vm_area_cachep, next); |
| 901 | /* |
| 902 | * In mprotect's case 6 (see comments on vma_merge), |
| 903 | * we must remove another next too. It would clutter |
| 904 | * up the code too much to do both in one go. |
| 905 | */ |
| 906 | next = vma->vm_next; |
| 907 | if (remove_next == 2) |
| 908 | goto again; |
| 909 | else if (next) |
| 910 | vma_gap_update(next); |
| 911 | else |
| 912 | WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); |
| 913 | } |
| 914 | if (insert && file) |
| 915 | uprobe_mmap(insert); |
| 916 | |
| 917 | validate_mm(mm); |
| 918 | |
| 919 | return 0; |
| 920 | } |
| 921 | |
| 922 | /* |
| 923 | * If the vma has a ->close operation then the driver probably needs to release |
| 924 | * per-vma resources, so we don't attempt to merge those. |
| 925 | */ |
| 926 | static inline int is_mergeable_vma(struct vm_area_struct *vma, |
| 927 | struct file *file, unsigned long vm_flags, |
| 928 | const char __user *anon_name) |
| 929 | { |
| 930 | if (vma->vm_flags ^ vm_flags) |
| 931 | return 0; |
| 932 | if (vma->vm_file != file) |
| 933 | return 0; |
| 934 | if (vma->vm_ops && vma->vm_ops->close) |
| 935 | return 0; |
| 936 | if (vma_get_anon_name(vma) != anon_name) |
| 937 | return 0; |
| 938 | return 1; |
| 939 | } |
| 940 | |
| 941 | static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, |
| 942 | struct anon_vma *anon_vma2, |
| 943 | struct vm_area_struct *vma) |
| 944 | { |
| 945 | /* |
| 946 | * The list_is_singular() test is to avoid merging VMA cloned from |
| 947 | * parents. This can improve scalability caused by anon_vma lock. |
| 948 | */ |
| 949 | if ((!anon_vma1 || !anon_vma2) && (!vma || |
| 950 | list_is_singular(&vma->anon_vma_chain))) |
| 951 | return 1; |
| 952 | return anon_vma1 == anon_vma2; |
| 953 | } |
| 954 | |
| 955 | /* |
| 956 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| 957 | * in front of (at a lower virtual address and file offset than) the vma. |
| 958 | * |
| 959 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
| 960 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| 961 | * |
| 962 | * We don't check here for the merged mmap wrapping around the end of pagecache |
| 963 | * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which |
| 964 | * wrap, nor mmaps which cover the final page at index -1UL. |
| 965 | */ |
| 966 | static int |
| 967 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, |
| 968 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff, |
| 969 | const char __user *anon_name) |
| 970 | { |
| 971 | if (is_mergeable_vma(vma, file, vm_flags, anon_name) && |
| 972 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| 973 | if (vma->vm_pgoff == vm_pgoff) |
| 974 | return 1; |
| 975 | } |
| 976 | return 0; |
| 977 | } |
| 978 | |
| 979 | /* |
| 980 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| 981 | * beyond (at a higher virtual address and file offset than) the vma. |
| 982 | * |
| 983 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
| 984 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| 985 | */ |
| 986 | static int |
| 987 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, |
| 988 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff, |
| 989 | const char __user *anon_name) |
| 990 | { |
| 991 | if (is_mergeable_vma(vma, file, vm_flags, anon_name) && |
| 992 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| 993 | pgoff_t vm_pglen; |
| 994 | vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; |
| 995 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) |
| 996 | return 1; |
| 997 | } |
| 998 | return 0; |
| 999 | } |
| 1000 | |
| 1001 | /* |
| 1002 | * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name), |
| 1003 | * figure out whether that can be merged with its predecessor or its |
| 1004 | * successor. Or both (it neatly fills a hole). |
| 1005 | * |
| 1006 | * In most cases - when called for mmap, brk or mremap - [addr,end) is |
| 1007 | * certain not to be mapped by the time vma_merge is called; but when |
| 1008 | * called for mprotect, it is certain to be already mapped (either at |
| 1009 | * an offset within prev, or at the start of next), and the flags of |
| 1010 | * this area are about to be changed to vm_flags - and the no-change |
| 1011 | * case has already been eliminated. |
| 1012 | * |
| 1013 | * The following mprotect cases have to be considered, where AAAA is |
| 1014 | * the area passed down from mprotect_fixup, never extending beyond one |
| 1015 | * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: |
| 1016 | * |
| 1017 | * AAAA AAAA AAAA AAAA |
| 1018 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX |
| 1019 | * cannot merge might become might become might become |
| 1020 | * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or |
| 1021 | * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or |
| 1022 | * mremap move: PPPPNNNNNNNN 8 |
| 1023 | * AAAA |
| 1024 | * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN |
| 1025 | * might become case 1 below case 2 below case 3 below |
| 1026 | * |
| 1027 | * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: |
| 1028 | * mprotect_fixup updates vm_flags & vm_page_prot on successful return. |
| 1029 | */ |
| 1030 | struct vm_area_struct *vma_merge(struct mm_struct *mm, |
| 1031 | struct vm_area_struct *prev, unsigned long addr, |
| 1032 | unsigned long end, unsigned long vm_flags, |
| 1033 | struct anon_vma *anon_vma, struct file *file, |
| 1034 | pgoff_t pgoff, struct mempolicy *policy, |
| 1035 | const char __user *anon_name) |
| 1036 | { |
| 1037 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; |
| 1038 | struct vm_area_struct *area, *next; |
| 1039 | int err; |
| 1040 | |
| 1041 | /* |
| 1042 | * We later require that vma->vm_flags == vm_flags, |
| 1043 | * so this tests vma->vm_flags & VM_SPECIAL, too. |
| 1044 | */ |
| 1045 | if (vm_flags & VM_SPECIAL) |
| 1046 | return NULL; |
| 1047 | |
| 1048 | if (prev) |
| 1049 | next = prev->vm_next; |
| 1050 | else |
| 1051 | next = mm->mmap; |
| 1052 | area = next; |
| 1053 | if (next && next->vm_end == end) /* cases 6, 7, 8 */ |
| 1054 | next = next->vm_next; |
| 1055 | |
| 1056 | /* |
| 1057 | * Can it merge with the predecessor? |
| 1058 | */ |
| 1059 | if (prev && prev->vm_end == addr && |
| 1060 | mpol_equal(vma_policy(prev), policy) && |
| 1061 | can_vma_merge_after(prev, vm_flags, anon_vma, |
| 1062 | file, pgoff, anon_name)) { |
| 1063 | /* |
| 1064 | * OK, it can. Can we now merge in the successor as well? |
| 1065 | */ |
| 1066 | if (next && end == next->vm_start && |
| 1067 | mpol_equal(policy, vma_policy(next)) && |
| 1068 | can_vma_merge_before(next, vm_flags, anon_vma, |
| 1069 | file, pgoff+pglen, anon_name) && |
| 1070 | is_mergeable_anon_vma(prev->anon_vma, |
| 1071 | next->anon_vma, NULL)) { |
| 1072 | /* cases 1, 6 */ |
| 1073 | err = vma_adjust(prev, prev->vm_start, |
| 1074 | next->vm_end, prev->vm_pgoff, NULL); |
| 1075 | } else /* cases 2, 5, 7 */ |
| 1076 | err = vma_adjust(prev, prev->vm_start, |
| 1077 | end, prev->vm_pgoff, NULL); |
| 1078 | if (err) |
| 1079 | return NULL; |
| 1080 | khugepaged_enter_vma_merge(prev); |
| 1081 | return prev; |
| 1082 | } |
| 1083 | |
| 1084 | /* |
| 1085 | * Can this new request be merged in front of next? |
| 1086 | */ |
| 1087 | if (next && end == next->vm_start && |
| 1088 | mpol_equal(policy, vma_policy(next)) && |
| 1089 | can_vma_merge_before(next, vm_flags, anon_vma, |
| 1090 | file, pgoff+pglen, anon_name)) { |
| 1091 | if (prev && addr < prev->vm_end) /* case 4 */ |
| 1092 | err = vma_adjust(prev, prev->vm_start, |
| 1093 | addr, prev->vm_pgoff, NULL); |
| 1094 | else /* cases 3, 8 */ |
| 1095 | err = vma_adjust(area, addr, next->vm_end, |
| 1096 | next->vm_pgoff - pglen, NULL); |
| 1097 | if (err) |
| 1098 | return NULL; |
| 1099 | khugepaged_enter_vma_merge(area); |
| 1100 | return area; |
| 1101 | } |
| 1102 | |
| 1103 | return NULL; |
| 1104 | } |
| 1105 | |
| 1106 | /* |
| 1107 | * Rough compatbility check to quickly see if it's even worth looking |
| 1108 | * at sharing an anon_vma. |
| 1109 | * |
| 1110 | * They need to have the same vm_file, and the flags can only differ |
| 1111 | * in things that mprotect may change. |
| 1112 | * |
| 1113 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that |
| 1114 | * we can merge the two vma's. For example, we refuse to merge a vma if |
| 1115 | * there is a vm_ops->close() function, because that indicates that the |
| 1116 | * driver is doing some kind of reference counting. But that doesn't |
| 1117 | * really matter for the anon_vma sharing case. |
| 1118 | */ |
| 1119 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) |
| 1120 | { |
| 1121 | return a->vm_end == b->vm_start && |
| 1122 | mpol_equal(vma_policy(a), vma_policy(b)) && |
| 1123 | a->vm_file == b->vm_file && |
| 1124 | !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) && |
| 1125 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); |
| 1126 | } |
| 1127 | |
| 1128 | /* |
| 1129 | * Do some basic sanity checking to see if we can re-use the anon_vma |
| 1130 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be |
| 1131 | * the same as 'old', the other will be the new one that is trying |
| 1132 | * to share the anon_vma. |
| 1133 | * |
| 1134 | * NOTE! This runs with mm_sem held for reading, so it is possible that |
| 1135 | * the anon_vma of 'old' is concurrently in the process of being set up |
| 1136 | * by another page fault trying to merge _that_. But that's ok: if it |
| 1137 | * is being set up, that automatically means that it will be a singleton |
| 1138 | * acceptable for merging, so we can do all of this optimistically. But |
| 1139 | * we do that ACCESS_ONCE() to make sure that we never re-load the pointer. |
| 1140 | * |
| 1141 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only |
| 1142 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid |
| 1143 | * is to return an anon_vma that is "complex" due to having gone through |
| 1144 | * a fork). |
| 1145 | * |
| 1146 | * We also make sure that the two vma's are compatible (adjacent, |
| 1147 | * and with the same memory policies). That's all stable, even with just |
| 1148 | * a read lock on the mm_sem. |
| 1149 | */ |
| 1150 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) |
| 1151 | { |
| 1152 | if (anon_vma_compatible(a, b)) { |
| 1153 | struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma); |
| 1154 | |
| 1155 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) |
| 1156 | return anon_vma; |
| 1157 | } |
| 1158 | return NULL; |
| 1159 | } |
| 1160 | |
| 1161 | /* |
| 1162 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check |
| 1163 | * neighbouring vmas for a suitable anon_vma, before it goes off |
| 1164 | * to allocate a new anon_vma. It checks because a repetitive |
| 1165 | * sequence of mprotects and faults may otherwise lead to distinct |
| 1166 | * anon_vmas being allocated, preventing vma merge in subsequent |
| 1167 | * mprotect. |
| 1168 | */ |
| 1169 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) |
| 1170 | { |
| 1171 | struct anon_vma *anon_vma; |
| 1172 | struct vm_area_struct *near; |
| 1173 | |
| 1174 | near = vma->vm_next; |
| 1175 | if (!near) |
| 1176 | goto try_prev; |
| 1177 | |
| 1178 | anon_vma = reusable_anon_vma(near, vma, near); |
| 1179 | if (anon_vma) |
| 1180 | return anon_vma; |
| 1181 | try_prev: |
| 1182 | near = vma->vm_prev; |
| 1183 | if (!near) |
| 1184 | goto none; |
| 1185 | |
| 1186 | anon_vma = reusable_anon_vma(near, near, vma); |
| 1187 | if (anon_vma) |
| 1188 | return anon_vma; |
| 1189 | none: |
| 1190 | /* |
| 1191 | * There's no absolute need to look only at touching neighbours: |
| 1192 | * we could search further afield for "compatible" anon_vmas. |
| 1193 | * But it would probably just be a waste of time searching, |
| 1194 | * or lead to too many vmas hanging off the same anon_vma. |
| 1195 | * We're trying to allow mprotect remerging later on, |
| 1196 | * not trying to minimize memory used for anon_vmas. |
| 1197 | */ |
| 1198 | return NULL; |
| 1199 | } |
| 1200 | |
| 1201 | #ifdef CONFIG_PROC_FS |
| 1202 | void vm_stat_account(struct mm_struct *mm, unsigned long flags, |
| 1203 | struct file *file, long pages) |
| 1204 | { |
| 1205 | const unsigned long stack_flags |
| 1206 | = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); |
| 1207 | |
| 1208 | mm->total_vm += pages; |
| 1209 | |
| 1210 | if (file) { |
| 1211 | mm->shared_vm += pages; |
| 1212 | if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) |
| 1213 | mm->exec_vm += pages; |
| 1214 | } else if (flags & stack_flags) |
| 1215 | mm->stack_vm += pages; |
| 1216 | } |
| 1217 | #endif /* CONFIG_PROC_FS */ |
| 1218 | |
| 1219 | /* |
| 1220 | * If a hint addr is less than mmap_min_addr change hint to be as |
| 1221 | * low as possible but still greater than mmap_min_addr |
| 1222 | */ |
| 1223 | static inline unsigned long round_hint_to_min(unsigned long hint) |
| 1224 | { |
| 1225 | hint &= PAGE_MASK; |
| 1226 | if (((void *)hint != NULL) && |
| 1227 | (hint < mmap_min_addr)) |
| 1228 | return PAGE_ALIGN(mmap_min_addr); |
| 1229 | return hint; |
| 1230 | } |
| 1231 | |
| 1232 | /* |
| 1233 | * The caller must hold down_write(¤t->mm->mmap_sem). |
| 1234 | */ |
| 1235 | |
| 1236 | unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, |
| 1237 | unsigned long len, unsigned long prot, |
| 1238 | unsigned long flags, unsigned long pgoff, |
| 1239 | unsigned long *populate) |
| 1240 | { |
| 1241 | struct mm_struct * mm = current->mm; |
| 1242 | vm_flags_t vm_flags; |
| 1243 | |
| 1244 | *populate = 0; |
| 1245 | |
| 1246 | while (file && (file->f_mode & FMODE_NONMAPPABLE)) |
| 1247 | file = file->f_op->get_lower_file(file); |
| 1248 | |
| 1249 | /* |
| 1250 | * Does the application expect PROT_READ to imply PROT_EXEC? |
| 1251 | * |
| 1252 | * (the exception is when the underlying filesystem is noexec |
| 1253 | * mounted, in which case we dont add PROT_EXEC.) |
| 1254 | */ |
| 1255 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
| 1256 | if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) |
| 1257 | prot |= PROT_EXEC; |
| 1258 | |
| 1259 | if (!len) |
| 1260 | return -EINVAL; |
| 1261 | |
| 1262 | if (!(flags & MAP_FIXED)) |
| 1263 | addr = round_hint_to_min(addr); |
| 1264 | |
| 1265 | /* Careful about overflows.. */ |
| 1266 | len = PAGE_ALIGN(len); |
| 1267 | if (!len) |
| 1268 | return -ENOMEM; |
| 1269 | |
| 1270 | /* offset overflow? */ |
| 1271 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) |
| 1272 | return -EOVERFLOW; |
| 1273 | |
| 1274 | /* Too many mappings? */ |
| 1275 | if (mm->map_count > sysctl_max_map_count) |
| 1276 | return -ENOMEM; |
| 1277 | |
| 1278 | /* Obtain the address to map to. we verify (or select) it and ensure |
| 1279 | * that it represents a valid section of the address space. |
| 1280 | */ |
| 1281 | addr = get_unmapped_area(file, addr, len, pgoff, flags); |
| 1282 | if (addr & ~PAGE_MASK) |
| 1283 | return addr; |
| 1284 | |
| 1285 | /* Do simple checking here so the lower-level routines won't have |
| 1286 | * to. we assume access permissions have been handled by the open |
| 1287 | * of the memory object, so we don't do any here. |
| 1288 | */ |
| 1289 | vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | |
| 1290 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
| 1291 | |
| 1292 | if (flags & MAP_LOCKED) |
| 1293 | if (!can_do_mlock()) |
| 1294 | return -EPERM; |
| 1295 | |
| 1296 | /* mlock MCL_FUTURE? */ |
| 1297 | if (vm_flags & VM_LOCKED) { |
| 1298 | unsigned long locked, lock_limit; |
| 1299 | locked = len >> PAGE_SHIFT; |
| 1300 | locked += mm->locked_vm; |
| 1301 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
| 1302 | lock_limit >>= PAGE_SHIFT; |
| 1303 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
| 1304 | return -EAGAIN; |
| 1305 | } |
| 1306 | |
| 1307 | if (file) { |
| 1308 | struct inode *inode = file_inode(file); |
| 1309 | |
| 1310 | switch (flags & MAP_TYPE) { |
| 1311 | case MAP_SHARED: |
| 1312 | if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) |
| 1313 | return -EACCES; |
| 1314 | |
| 1315 | /* |
| 1316 | * Make sure we don't allow writing to an append-only |
| 1317 | * file.. |
| 1318 | */ |
| 1319 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) |
| 1320 | return -EACCES; |
| 1321 | |
| 1322 | /* |
| 1323 | * Make sure there are no mandatory locks on the file. |
| 1324 | */ |
| 1325 | if (locks_verify_locked(inode)) |
| 1326 | return -EAGAIN; |
| 1327 | |
| 1328 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
| 1329 | if (!(file->f_mode & FMODE_WRITE)) |
| 1330 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); |
| 1331 | |
| 1332 | /* fall through */ |
| 1333 | case MAP_PRIVATE: |
| 1334 | if (!(file->f_mode & FMODE_READ)) |
| 1335 | return -EACCES; |
| 1336 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { |
| 1337 | if (vm_flags & VM_EXEC) |
| 1338 | return -EPERM; |
| 1339 | vm_flags &= ~VM_MAYEXEC; |
| 1340 | } |
| 1341 | |
| 1342 | if (!file->f_op || !file->f_op->mmap) |
| 1343 | return -ENODEV; |
| 1344 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| 1345 | return -EINVAL; |
| 1346 | break; |
| 1347 | |
| 1348 | default: |
| 1349 | return -EINVAL; |
| 1350 | } |
| 1351 | } else { |
| 1352 | switch (flags & MAP_TYPE) { |
| 1353 | case MAP_SHARED: |
| 1354 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| 1355 | return -EINVAL; |
| 1356 | /* |
| 1357 | * Ignore pgoff. |
| 1358 | */ |
| 1359 | pgoff = 0; |
| 1360 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
| 1361 | break; |
| 1362 | case MAP_PRIVATE: |
| 1363 | /* |
| 1364 | * Set pgoff according to addr for anon_vma. |
| 1365 | */ |
| 1366 | pgoff = addr >> PAGE_SHIFT; |
| 1367 | break; |
| 1368 | default: |
| 1369 | return -EINVAL; |
| 1370 | } |
| 1371 | } |
| 1372 | |
| 1373 | /* |
| 1374 | * Set 'VM_NORESERVE' if we should not account for the |
| 1375 | * memory use of this mapping. |
| 1376 | */ |
| 1377 | if (flags & MAP_NORESERVE) { |
| 1378 | /* We honor MAP_NORESERVE if allowed to overcommit */ |
| 1379 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) |
| 1380 | vm_flags |= VM_NORESERVE; |
| 1381 | |
| 1382 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ |
| 1383 | if (file && is_file_hugepages(file)) |
| 1384 | vm_flags |= VM_NORESERVE; |
| 1385 | } |
| 1386 | |
| 1387 | addr = mmap_region(file, addr, len, vm_flags, pgoff); |
| 1388 | if (!IS_ERR_VALUE(addr) && |
| 1389 | ((vm_flags & VM_LOCKED) || |
| 1390 | (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) |
| 1391 | *populate = len; |
| 1392 | return addr; |
| 1393 | } |
| 1394 | |
| 1395 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
| 1396 | unsigned long, prot, unsigned long, flags, |
| 1397 | unsigned long, fd, unsigned long, pgoff) |
| 1398 | { |
| 1399 | struct file *file = NULL; |
| 1400 | unsigned long retval = -EBADF; |
| 1401 | |
| 1402 | if (!(flags & MAP_ANONYMOUS)) { |
| 1403 | audit_mmap_fd(fd, flags); |
| 1404 | if (unlikely(flags & MAP_HUGETLB)) |
| 1405 | return -EINVAL; |
| 1406 | file = fget(fd); |
| 1407 | if (!file) |
| 1408 | goto out; |
| 1409 | if (is_file_hugepages(file)) |
| 1410 | len = ALIGN(len, huge_page_size(hstate_file(file))); |
| 1411 | } else if (flags & MAP_HUGETLB) { |
| 1412 | struct user_struct *user = NULL; |
| 1413 | struct hstate *hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & |
| 1414 | SHM_HUGE_MASK); |
| 1415 | |
| 1416 | if (!hs) |
| 1417 | return -EINVAL; |
| 1418 | |
| 1419 | len = ALIGN(len, huge_page_size(hs)); |
| 1420 | /* |
| 1421 | * VM_NORESERVE is used because the reservations will be |
| 1422 | * taken when vm_ops->mmap() is called |
| 1423 | * A dummy user value is used because we are not locking |
| 1424 | * memory so no accounting is necessary |
| 1425 | */ |
| 1426 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, |
| 1427 | VM_NORESERVE, |
| 1428 | &user, HUGETLB_ANONHUGE_INODE, |
| 1429 | (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| 1430 | if (IS_ERR(file)) |
| 1431 | return PTR_ERR(file); |
| 1432 | } |
| 1433 | |
| 1434 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
| 1435 | |
| 1436 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
| 1437 | if (file) |
| 1438 | fput(file); |
| 1439 | out: |
| 1440 | return retval; |
| 1441 | } |
| 1442 | |
| 1443 | #ifdef __ARCH_WANT_SYS_OLD_MMAP |
| 1444 | struct mmap_arg_struct { |
| 1445 | unsigned long addr; |
| 1446 | unsigned long len; |
| 1447 | unsigned long prot; |
| 1448 | unsigned long flags; |
| 1449 | unsigned long fd; |
| 1450 | unsigned long offset; |
| 1451 | }; |
| 1452 | |
| 1453 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
| 1454 | { |
| 1455 | struct mmap_arg_struct a; |
| 1456 | |
| 1457 | if (copy_from_user(&a, arg, sizeof(a))) |
| 1458 | return -EFAULT; |
| 1459 | if (a.offset & ~PAGE_MASK) |
| 1460 | return -EINVAL; |
| 1461 | |
| 1462 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
| 1463 | a.offset >> PAGE_SHIFT); |
| 1464 | } |
| 1465 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
| 1466 | |
| 1467 | /* |
| 1468 | * Some shared mappigns will want the pages marked read-only |
| 1469 | * to track write events. If so, we'll downgrade vm_page_prot |
| 1470 | * to the private version (using protection_map[] without the |
| 1471 | * VM_SHARED bit). |
| 1472 | */ |
| 1473 | int vma_wants_writenotify(struct vm_area_struct *vma) |
| 1474 | { |
| 1475 | vm_flags_t vm_flags = vma->vm_flags; |
| 1476 | |
| 1477 | /* If it was private or non-writable, the write bit is already clear */ |
| 1478 | if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) |
| 1479 | return 0; |
| 1480 | |
| 1481 | /* The backer wishes to know when pages are first written to? */ |
| 1482 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) |
| 1483 | return 1; |
| 1484 | |
| 1485 | /* The open routine did something to the protections already? */ |
| 1486 | if (pgprot_val(vma->vm_page_prot) != |
| 1487 | pgprot_val(vm_get_page_prot(vm_flags))) |
| 1488 | return 0; |
| 1489 | |
| 1490 | /* Specialty mapping? */ |
| 1491 | if (vm_flags & VM_PFNMAP) |
| 1492 | return 0; |
| 1493 | |
| 1494 | /* Can the mapping track the dirty pages? */ |
| 1495 | return vma->vm_file && vma->vm_file->f_mapping && |
| 1496 | mapping_cap_account_dirty(vma->vm_file->f_mapping); |
| 1497 | } |
| 1498 | |
| 1499 | /* |
| 1500 | * We account for memory if it's a private writeable mapping, |
| 1501 | * not hugepages and VM_NORESERVE wasn't set. |
| 1502 | */ |
| 1503 | static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) |
| 1504 | { |
| 1505 | /* |
| 1506 | * hugetlb has its own accounting separate from the core VM |
| 1507 | * VM_HUGETLB may not be set yet so we cannot check for that flag. |
| 1508 | */ |
| 1509 | if (file && is_file_hugepages(file)) |
| 1510 | return 0; |
| 1511 | |
| 1512 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; |
| 1513 | } |
| 1514 | |
| 1515 | unsigned long mmap_region(struct file *file, unsigned long addr, |
| 1516 | unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) |
| 1517 | { |
| 1518 | struct mm_struct *mm = current->mm; |
| 1519 | struct vm_area_struct *vma, *prev; |
| 1520 | int error; |
| 1521 | struct rb_node **rb_link, *rb_parent; |
| 1522 | unsigned long charged = 0; |
| 1523 | |
| 1524 | /* Check against address space limit. */ |
| 1525 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) { |
| 1526 | unsigned long nr_pages; |
| 1527 | |
| 1528 | /* |
| 1529 | * MAP_FIXED may remove pages of mappings that intersects with |
| 1530 | * requested mapping. Account for the pages it would unmap. |
| 1531 | */ |
| 1532 | if (!(vm_flags & MAP_FIXED)) |
| 1533 | return -ENOMEM; |
| 1534 | |
| 1535 | nr_pages = count_vma_pages_range(mm, addr, addr + len); |
| 1536 | |
| 1537 | if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) |
| 1538 | return -ENOMEM; |
| 1539 | } |
| 1540 | |
| 1541 | /* Clear old maps */ |
| 1542 | error = -ENOMEM; |
| 1543 | munmap_back: |
| 1544 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { |
| 1545 | if (do_munmap(mm, addr, len)) |
| 1546 | return -ENOMEM; |
| 1547 | goto munmap_back; |
| 1548 | } |
| 1549 | |
| 1550 | /* |
| 1551 | * Private writable mapping: check memory availability |
| 1552 | */ |
| 1553 | if (accountable_mapping(file, vm_flags)) { |
| 1554 | charged = len >> PAGE_SHIFT; |
| 1555 | if (security_vm_enough_memory_mm(mm, charged)) |
| 1556 | return -ENOMEM; |
| 1557 | vm_flags |= VM_ACCOUNT; |
| 1558 | } |
| 1559 | |
| 1560 | /* |
| 1561 | * Can we just expand an old mapping? |
| 1562 | */ |
| 1563 | vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, |
| 1564 | NULL, NULL); |
| 1565 | if (vma) |
| 1566 | goto out; |
| 1567 | |
| 1568 | /* |
| 1569 | * Determine the object being mapped and call the appropriate |
| 1570 | * specific mapper. the address has already been validated, but |
| 1571 | * not unmapped, but the maps are removed from the list. |
| 1572 | */ |
| 1573 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| 1574 | if (!vma) { |
| 1575 | error = -ENOMEM; |
| 1576 | goto unacct_error; |
| 1577 | } |
| 1578 | |
| 1579 | vma->vm_mm = mm; |
| 1580 | vma->vm_start = addr; |
| 1581 | vma->vm_end = addr + len; |
| 1582 | vma->vm_flags = vm_flags; |
| 1583 | vma->vm_page_prot = vm_get_page_prot(vm_flags); |
| 1584 | vma->vm_pgoff = pgoff; |
| 1585 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
| 1586 | |
| 1587 | if (file) { |
| 1588 | if (vm_flags & VM_DENYWRITE) { |
| 1589 | error = deny_write_access(file); |
| 1590 | if (error) |
| 1591 | goto free_vma; |
| 1592 | } |
| 1593 | if (vm_flags & VM_SHARED) { |
| 1594 | error = mapping_map_writable(file->f_mapping); |
| 1595 | if (error) |
| 1596 | goto allow_write_and_free_vma; |
| 1597 | } |
| 1598 | |
| 1599 | /* ->mmap() can change vma->vm_file, but must guarantee that |
| 1600 | * vma_link() below can deny write-access if VM_DENYWRITE is set |
| 1601 | * and map writably if VM_SHARED is set. This usually means the |
| 1602 | * new file must not have been exposed to user-space, yet. |
| 1603 | */ |
| 1604 | vma->vm_file = get_file(file); |
| 1605 | error = file->f_op->mmap(file, vma); |
| 1606 | if (error) |
| 1607 | goto unmap_and_free_vma; |
| 1608 | |
| 1609 | /* Can addr have changed?? |
| 1610 | * |
| 1611 | * Answer: Yes, several device drivers can do it in their |
| 1612 | * f_op->mmap method. -DaveM |
| 1613 | * Bug: If addr is changed, prev, rb_link, rb_parent should |
| 1614 | * be updated for vma_link() |
| 1615 | */ |
| 1616 | WARN_ON_ONCE(addr != vma->vm_start); |
| 1617 | |
| 1618 | addr = vma->vm_start; |
| 1619 | pgoff = vma->vm_pgoff; |
| 1620 | vm_flags = vma->vm_flags; |
| 1621 | } else if (vm_flags & VM_SHARED) { |
| 1622 | error = shmem_zero_setup(vma); |
| 1623 | if (error) |
| 1624 | goto free_vma; |
| 1625 | } |
| 1626 | |
| 1627 | if (vma_wants_writenotify(vma)) { |
| 1628 | pgprot_t pprot = vma->vm_page_prot; |
| 1629 | |
| 1630 | /* Can vma->vm_page_prot have changed?? |
| 1631 | * |
| 1632 | * Answer: Yes, drivers may have changed it in their |
| 1633 | * f_op->mmap method. |
| 1634 | * |
| 1635 | * Ensures that vmas marked as uncached stay that way. |
| 1636 | */ |
| 1637 | vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); |
| 1638 | if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot))) |
| 1639 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
| 1640 | } |
| 1641 | |
| 1642 | vma_link(mm, vma, prev, rb_link, rb_parent); |
| 1643 | /* Once vma denies write, undo our temporary denial count */ |
| 1644 | if (file) { |
| 1645 | if (vm_flags & VM_SHARED) |
| 1646 | mapping_unmap_writable(file->f_mapping); |
| 1647 | if (vm_flags & VM_DENYWRITE) |
| 1648 | allow_write_access(file); |
| 1649 | } |
| 1650 | file = vma->vm_file; |
| 1651 | out: |
| 1652 | perf_event_mmap(vma); |
| 1653 | |
| 1654 | vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); |
| 1655 | if (vm_flags & VM_LOCKED) { |
| 1656 | if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || |
| 1657 | vma == get_gate_vma(current->mm))) |
| 1658 | mm->locked_vm += (len >> PAGE_SHIFT); |
| 1659 | else |
| 1660 | vma->vm_flags &= ~VM_LOCKED; |
| 1661 | } |
| 1662 | |
| 1663 | if (file) |
| 1664 | uprobe_mmap(vma); |
| 1665 | |
| 1666 | return addr; |
| 1667 | |
| 1668 | unmap_and_free_vma: |
| 1669 | vma->vm_file = NULL; |
| 1670 | fput(file); |
| 1671 | |
| 1672 | /* Undo any partial mapping done by a device driver. */ |
| 1673 | unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); |
| 1674 | charged = 0; |
| 1675 | if (vm_flags & VM_SHARED) |
| 1676 | mapping_unmap_writable(file->f_mapping); |
| 1677 | allow_write_and_free_vma: |
| 1678 | if (vm_flags & VM_DENYWRITE) |
| 1679 | allow_write_access(file); |
| 1680 | free_vma: |
| 1681 | kmem_cache_free(vm_area_cachep, vma); |
| 1682 | unacct_error: |
| 1683 | if (charged) |
| 1684 | vm_unacct_memory(charged); |
| 1685 | return error; |
| 1686 | } |
| 1687 | |
| 1688 | unsigned long unmapped_area(struct vm_unmapped_area_info *info) |
| 1689 | { |
| 1690 | /* |
| 1691 | * We implement the search by looking for an rbtree node that |
| 1692 | * immediately follows a suitable gap. That is, |
| 1693 | * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; |
| 1694 | * - gap_end = vma->vm_start >= info->low_limit + length; |
| 1695 | * - gap_end - gap_start >= length |
| 1696 | */ |
| 1697 | |
| 1698 | struct mm_struct *mm = current->mm; |
| 1699 | struct vm_area_struct *vma; |
| 1700 | unsigned long length, low_limit, high_limit, gap_start, gap_end; |
| 1701 | |
| 1702 | /* Adjust search length to account for worst case alignment overhead */ |
| 1703 | length = info->length + info->align_mask; |
| 1704 | if (length < info->length) |
| 1705 | return -ENOMEM; |
| 1706 | |
| 1707 | /* Adjust search limits by the desired length */ |
| 1708 | if (info->high_limit < length) |
| 1709 | return -ENOMEM; |
| 1710 | high_limit = info->high_limit - length; |
| 1711 | |
| 1712 | if (info->low_limit > high_limit) |
| 1713 | return -ENOMEM; |
| 1714 | low_limit = info->low_limit + length; |
| 1715 | |
| 1716 | /* Check if rbtree root looks promising */ |
| 1717 | if (RB_EMPTY_ROOT(&mm->mm_rb)) |
| 1718 | goto check_highest; |
| 1719 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); |
| 1720 | if (vma->rb_subtree_gap < length) |
| 1721 | goto check_highest; |
| 1722 | |
| 1723 | while (true) { |
| 1724 | /* Visit left subtree if it looks promising */ |
| 1725 | gap_end = vm_start_gap(vma); |
| 1726 | if (gap_end >= low_limit && vma->vm_rb.rb_left) { |
| 1727 | struct vm_area_struct *left = |
| 1728 | rb_entry(vma->vm_rb.rb_left, |
| 1729 | struct vm_area_struct, vm_rb); |
| 1730 | if (left->rb_subtree_gap >= length) { |
| 1731 | vma = left; |
| 1732 | continue; |
| 1733 | } |
| 1734 | } |
| 1735 | |
| 1736 | gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; |
| 1737 | check_current: |
| 1738 | /* Check if current node has a suitable gap */ |
| 1739 | if (gap_start > high_limit) |
| 1740 | return -ENOMEM; |
| 1741 | if (gap_end >= low_limit && |
| 1742 | gap_end > gap_start && gap_end - gap_start >= length) |
| 1743 | goto found; |
| 1744 | |
| 1745 | /* Visit right subtree if it looks promising */ |
| 1746 | if (vma->vm_rb.rb_right) { |
| 1747 | struct vm_area_struct *right = |
| 1748 | rb_entry(vma->vm_rb.rb_right, |
| 1749 | struct vm_area_struct, vm_rb); |
| 1750 | if (right->rb_subtree_gap >= length) { |
| 1751 | vma = right; |
| 1752 | continue; |
| 1753 | } |
| 1754 | } |
| 1755 | |
| 1756 | /* Go back up the rbtree to find next candidate node */ |
| 1757 | while (true) { |
| 1758 | struct rb_node *prev = &vma->vm_rb; |
| 1759 | if (!rb_parent(prev)) |
| 1760 | goto check_highest; |
| 1761 | vma = rb_entry(rb_parent(prev), |
| 1762 | struct vm_area_struct, vm_rb); |
| 1763 | if (prev == vma->vm_rb.rb_left) { |
| 1764 | gap_start = vm_end_gap(vma->vm_prev); |
| 1765 | gap_end = vm_start_gap(vma); |
| 1766 | goto check_current; |
| 1767 | } |
| 1768 | } |
| 1769 | } |
| 1770 | |
| 1771 | check_highest: |
| 1772 | /* Check highest gap, which does not precede any rbtree node */ |
| 1773 | gap_start = mm->highest_vm_end; |
| 1774 | gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ |
| 1775 | if (gap_start > high_limit) |
| 1776 | return -ENOMEM; |
| 1777 | |
| 1778 | found: |
| 1779 | /* We found a suitable gap. Clip it with the original low_limit. */ |
| 1780 | if (gap_start < info->low_limit) |
| 1781 | gap_start = info->low_limit; |
| 1782 | |
| 1783 | /* Adjust gap address to the desired alignment */ |
| 1784 | gap_start += (info->align_offset - gap_start) & info->align_mask; |
| 1785 | |
| 1786 | VM_BUG_ON(gap_start + info->length > info->high_limit); |
| 1787 | VM_BUG_ON(gap_start + info->length > gap_end); |
| 1788 | return gap_start; |
| 1789 | } |
| 1790 | |
| 1791 | unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) |
| 1792 | { |
| 1793 | struct mm_struct *mm = current->mm; |
| 1794 | struct vm_area_struct *vma; |
| 1795 | unsigned long length, low_limit, high_limit, gap_start, gap_end; |
| 1796 | |
| 1797 | /* Adjust search length to account for worst case alignment overhead */ |
| 1798 | length = info->length + info->align_mask; |
| 1799 | if (length < info->length) |
| 1800 | return -ENOMEM; |
| 1801 | |
| 1802 | /* |
| 1803 | * Adjust search limits by the desired length. |
| 1804 | * See implementation comment at top of unmapped_area(). |
| 1805 | */ |
| 1806 | gap_end = info->high_limit; |
| 1807 | if (gap_end < length) |
| 1808 | return -ENOMEM; |
| 1809 | high_limit = gap_end - length; |
| 1810 | |
| 1811 | if (info->low_limit > high_limit) |
| 1812 | return -ENOMEM; |
| 1813 | low_limit = info->low_limit + length; |
| 1814 | |
| 1815 | /* Check highest gap, which does not precede any rbtree node */ |
| 1816 | gap_start = mm->highest_vm_end; |
| 1817 | if (gap_start <= high_limit) |
| 1818 | goto found_highest; |
| 1819 | |
| 1820 | /* Check if rbtree root looks promising */ |
| 1821 | if (RB_EMPTY_ROOT(&mm->mm_rb)) |
| 1822 | return -ENOMEM; |
| 1823 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); |
| 1824 | if (vma->rb_subtree_gap < length) |
| 1825 | return -ENOMEM; |
| 1826 | |
| 1827 | while (true) { |
| 1828 | /* Visit right subtree if it looks promising */ |
| 1829 | gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; |
| 1830 | if (gap_start <= high_limit && vma->vm_rb.rb_right) { |
| 1831 | struct vm_area_struct *right = |
| 1832 | rb_entry(vma->vm_rb.rb_right, |
| 1833 | struct vm_area_struct, vm_rb); |
| 1834 | if (right->rb_subtree_gap >= length) { |
| 1835 | vma = right; |
| 1836 | continue; |
| 1837 | } |
| 1838 | } |
| 1839 | |
| 1840 | check_current: |
| 1841 | /* Check if current node has a suitable gap */ |
| 1842 | gap_end = vm_start_gap(vma); |
| 1843 | if (gap_end < low_limit) |
| 1844 | return -ENOMEM; |
| 1845 | if (gap_start <= high_limit && |
| 1846 | gap_end > gap_start && gap_end - gap_start >= length) |
| 1847 | goto found; |
| 1848 | |
| 1849 | /* Visit left subtree if it looks promising */ |
| 1850 | if (vma->vm_rb.rb_left) { |
| 1851 | struct vm_area_struct *left = |
| 1852 | rb_entry(vma->vm_rb.rb_left, |
| 1853 | struct vm_area_struct, vm_rb); |
| 1854 | if (left->rb_subtree_gap >= length) { |
| 1855 | vma = left; |
| 1856 | continue; |
| 1857 | } |
| 1858 | } |
| 1859 | |
| 1860 | /* Go back up the rbtree to find next candidate node */ |
| 1861 | while (true) { |
| 1862 | struct rb_node *prev = &vma->vm_rb; |
| 1863 | if (!rb_parent(prev)) |
| 1864 | return -ENOMEM; |
| 1865 | vma = rb_entry(rb_parent(prev), |
| 1866 | struct vm_area_struct, vm_rb); |
| 1867 | if (prev == vma->vm_rb.rb_right) { |
| 1868 | gap_start = vma->vm_prev ? |
| 1869 | vm_end_gap(vma->vm_prev) : 0; |
| 1870 | goto check_current; |
| 1871 | } |
| 1872 | } |
| 1873 | } |
| 1874 | |
| 1875 | found: |
| 1876 | /* We found a suitable gap. Clip it with the original high_limit. */ |
| 1877 | if (gap_end > info->high_limit) |
| 1878 | gap_end = info->high_limit; |
| 1879 | |
| 1880 | found_highest: |
| 1881 | /* Compute highest gap address at the desired alignment */ |
| 1882 | gap_end -= info->length; |
| 1883 | gap_end -= (gap_end - info->align_offset) & info->align_mask; |
| 1884 | |
| 1885 | VM_BUG_ON(gap_end < info->low_limit); |
| 1886 | VM_BUG_ON(gap_end < gap_start); |
| 1887 | return gap_end; |
| 1888 | } |
| 1889 | |
| 1890 | /* Get an address range which is currently unmapped. |
| 1891 | * For shmat() with addr=0. |
| 1892 | * |
| 1893 | * Ugly calling convention alert: |
| 1894 | * Return value with the low bits set means error value, |
| 1895 | * ie |
| 1896 | * if (ret & ~PAGE_MASK) |
| 1897 | * error = ret; |
| 1898 | * |
| 1899 | * This function "knows" that -ENOMEM has the bits set. |
| 1900 | */ |
| 1901 | #ifndef HAVE_ARCH_UNMAPPED_AREA |
| 1902 | unsigned long |
| 1903 | arch_get_unmapped_area(struct file *filp, unsigned long addr, |
| 1904 | unsigned long len, unsigned long pgoff, unsigned long flags) |
| 1905 | { |
| 1906 | struct mm_struct *mm = current->mm; |
| 1907 | struct vm_area_struct *vma, *prev; |
| 1908 | struct vm_unmapped_area_info info; |
| 1909 | |
| 1910 | if (len > TASK_SIZE - mmap_min_addr) |
| 1911 | return -ENOMEM; |
| 1912 | |
| 1913 | if (flags & MAP_FIXED) |
| 1914 | return addr; |
| 1915 | |
| 1916 | if (addr) { |
| 1917 | addr = PAGE_ALIGN(addr); |
| 1918 | vma = find_vma_prev(mm, addr, &prev); |
| 1919 | if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && |
| 1920 | (!vma || addr + len <= vm_start_gap(vma)) && |
| 1921 | (!prev || addr >= vm_end_gap(prev))) |
| 1922 | return addr; |
| 1923 | } |
| 1924 | |
| 1925 | info.flags = 0; |
| 1926 | info.length = len; |
| 1927 | info.low_limit = TASK_UNMAPPED_BASE; |
| 1928 | info.high_limit = TASK_SIZE; |
| 1929 | info.align_mask = 0; |
| 1930 | return vm_unmapped_area(&info); |
| 1931 | } |
| 1932 | #endif |
| 1933 | |
| 1934 | void arch_unmap_area(struct mm_struct *mm, unsigned long addr) |
| 1935 | { |
| 1936 | /* |
| 1937 | * Is this a new hole at the lowest possible address? |
| 1938 | */ |
| 1939 | if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) |
| 1940 | mm->free_area_cache = addr; |
| 1941 | } |
| 1942 | |
| 1943 | /* |
| 1944 | * This mmap-allocator allocates new areas top-down from below the |
| 1945 | * stack's low limit (the base): |
| 1946 | */ |
| 1947 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN |
| 1948 | unsigned long |
| 1949 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, |
| 1950 | const unsigned long len, const unsigned long pgoff, |
| 1951 | const unsigned long flags) |
| 1952 | { |
| 1953 | struct vm_area_struct *vma, *prev; |
| 1954 | struct mm_struct *mm = current->mm; |
| 1955 | unsigned long addr = addr0; |
| 1956 | struct vm_unmapped_area_info info; |
| 1957 | |
| 1958 | /* requested length too big for entire address space */ |
| 1959 | if (len > TASK_SIZE - mmap_min_addr) |
| 1960 | return -ENOMEM; |
| 1961 | |
| 1962 | if (flags & MAP_FIXED) |
| 1963 | return addr; |
| 1964 | |
| 1965 | /* requesting a specific address */ |
| 1966 | if (addr) { |
| 1967 | addr = PAGE_ALIGN(addr); |
| 1968 | vma = find_vma_prev(mm, addr, &prev); |
| 1969 | if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && |
| 1970 | (!vma || addr + len <= vm_start_gap(vma)) && |
| 1971 | (!prev || addr >= vm_end_gap(prev))) |
| 1972 | return addr; |
| 1973 | } |
| 1974 | |
| 1975 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; |
| 1976 | info.length = len; |
| 1977 | info.low_limit = max(PAGE_SIZE, mmap_min_addr); |
| 1978 | info.high_limit = mm->mmap_base; |
| 1979 | info.align_mask = 0; |
| 1980 | addr = vm_unmapped_area(&info); |
| 1981 | |
| 1982 | /* |
| 1983 | * A failed mmap() very likely causes application failure, |
| 1984 | * so fall back to the bottom-up function here. This scenario |
| 1985 | * can happen with large stack limits and large mmap() |
| 1986 | * allocations. |
| 1987 | */ |
| 1988 | if (addr & ~PAGE_MASK) { |
| 1989 | VM_BUG_ON(addr != -ENOMEM); |
| 1990 | info.flags = 0; |
| 1991 | info.low_limit = TASK_UNMAPPED_BASE; |
| 1992 | info.high_limit = TASK_SIZE; |
| 1993 | addr = vm_unmapped_area(&info); |
| 1994 | } |
| 1995 | |
| 1996 | return addr; |
| 1997 | } |
| 1998 | #endif |
| 1999 | |
| 2000 | void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) |
| 2001 | { |
| 2002 | /* |
| 2003 | * Is this a new hole at the highest possible address? |
| 2004 | */ |
| 2005 | if (addr > mm->free_area_cache) |
| 2006 | mm->free_area_cache = addr; |
| 2007 | |
| 2008 | /* dont allow allocations above current base */ |
| 2009 | if (mm->free_area_cache > mm->mmap_base) |
| 2010 | mm->free_area_cache = mm->mmap_base; |
| 2011 | } |
| 2012 | |
| 2013 | unsigned long |
| 2014 | get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, |
| 2015 | unsigned long pgoff, unsigned long flags) |
| 2016 | { |
| 2017 | unsigned long (*get_area)(struct file *, unsigned long, |
| 2018 | unsigned long, unsigned long, unsigned long); |
| 2019 | |
| 2020 | unsigned long error = arch_mmap_check(addr, len, flags); |
| 2021 | if (error) |
| 2022 | return error; |
| 2023 | |
| 2024 | /* Careful about overflows.. */ |
| 2025 | if (len > TASK_SIZE) |
| 2026 | return -ENOMEM; |
| 2027 | |
| 2028 | get_area = current->mm->get_unmapped_area; |
| 2029 | if (file && file->f_op && file->f_op->get_unmapped_area) |
| 2030 | get_area = file->f_op->get_unmapped_area; |
| 2031 | addr = get_area(file, addr, len, pgoff, flags); |
| 2032 | if (IS_ERR_VALUE(addr)) |
| 2033 | return addr; |
| 2034 | |
| 2035 | if (addr > TASK_SIZE - len) |
| 2036 | return -ENOMEM; |
| 2037 | if (addr & ~PAGE_MASK) |
| 2038 | return -EINVAL; |
| 2039 | |
| 2040 | addr = arch_rebalance_pgtables(addr, len); |
| 2041 | error = security_mmap_addr(addr); |
| 2042 | return error ? error : addr; |
| 2043 | } |
| 2044 | |
| 2045 | EXPORT_SYMBOL(get_unmapped_area); |
| 2046 | |
| 2047 | /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ |
| 2048 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
| 2049 | { |
| 2050 | struct rb_node *rb_node; |
| 2051 | struct vm_area_struct *vma; |
| 2052 | |
| 2053 | /* Check the cache first. */ |
| 2054 | vma = vmacache_find(mm, addr); |
| 2055 | if (likely(vma)) |
| 2056 | return vma; |
| 2057 | |
| 2058 | rb_node = mm->mm_rb.rb_node; |
| 2059 | vma = NULL; |
| 2060 | |
| 2061 | while (rb_node) { |
| 2062 | struct vm_area_struct *tmp; |
| 2063 | |
| 2064 | tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); |
| 2065 | |
| 2066 | if (tmp->vm_end > addr) { |
| 2067 | vma = tmp; |
| 2068 | if (tmp->vm_start <= addr) |
| 2069 | break; |
| 2070 | rb_node = rb_node->rb_left; |
| 2071 | } else |
| 2072 | rb_node = rb_node->rb_right; |
| 2073 | } |
| 2074 | |
| 2075 | if (vma) |
| 2076 | vmacache_update(addr, vma); |
| 2077 | return vma; |
| 2078 | } |
| 2079 | |
| 2080 | EXPORT_SYMBOL(find_vma); |
| 2081 | |
| 2082 | /* |
| 2083 | * Same as find_vma, but also return a pointer to the previous VMA in *pprev. |
| 2084 | */ |
| 2085 | struct vm_area_struct * |
| 2086 | find_vma_prev(struct mm_struct *mm, unsigned long addr, |
| 2087 | struct vm_area_struct **pprev) |
| 2088 | { |
| 2089 | struct vm_area_struct *vma; |
| 2090 | |
| 2091 | vma = find_vma(mm, addr); |
| 2092 | if (vma) { |
| 2093 | *pprev = vma->vm_prev; |
| 2094 | } else { |
| 2095 | struct rb_node *rb_node = mm->mm_rb.rb_node; |
| 2096 | *pprev = NULL; |
| 2097 | while (rb_node) { |
| 2098 | *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); |
| 2099 | rb_node = rb_node->rb_right; |
| 2100 | } |
| 2101 | } |
| 2102 | return vma; |
| 2103 | } |
| 2104 | |
| 2105 | /* |
| 2106 | * Verify that the stack growth is acceptable and |
| 2107 | * update accounting. This is shared with both the |
| 2108 | * grow-up and grow-down cases. |
| 2109 | */ |
| 2110 | static int acct_stack_growth(struct vm_area_struct *vma, |
| 2111 | unsigned long size, unsigned long grow) |
| 2112 | { |
| 2113 | struct mm_struct *mm = vma->vm_mm; |
| 2114 | struct rlimit *rlim = current->signal->rlim; |
| 2115 | unsigned long new_start; |
| 2116 | |
| 2117 | /* address space limit tests */ |
| 2118 | if (!may_expand_vm(mm, grow)) |
| 2119 | return -ENOMEM; |
| 2120 | |
| 2121 | /* Stack limit test */ |
| 2122 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur)) |
| 2123 | return -ENOMEM; |
| 2124 | |
| 2125 | /* mlock limit tests */ |
| 2126 | if (vma->vm_flags & VM_LOCKED) { |
| 2127 | unsigned long locked; |
| 2128 | unsigned long limit; |
| 2129 | locked = mm->locked_vm + grow; |
| 2130 | limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); |
| 2131 | limit >>= PAGE_SHIFT; |
| 2132 | if (locked > limit && !capable(CAP_IPC_LOCK)) |
| 2133 | return -ENOMEM; |
| 2134 | } |
| 2135 | |
| 2136 | /* Check to ensure the stack will not grow into a hugetlb-only region */ |
| 2137 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : |
| 2138 | vma->vm_end - size; |
| 2139 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) |
| 2140 | return -EFAULT; |
| 2141 | |
| 2142 | /* |
| 2143 | * Overcommit.. This must be the final test, as it will |
| 2144 | * update security statistics. |
| 2145 | */ |
| 2146 | if (security_vm_enough_memory_mm(mm, grow)) |
| 2147 | return -ENOMEM; |
| 2148 | |
| 2149 | /* Ok, everything looks good - let it rip */ |
| 2150 | if (vma->vm_flags & VM_LOCKED) |
| 2151 | mm->locked_vm += grow; |
| 2152 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); |
| 2153 | return 0; |
| 2154 | } |
| 2155 | |
| 2156 | #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) |
| 2157 | /* |
| 2158 | * PA-RISC uses this for its stack; IA64 for its Register Backing Store. |
| 2159 | * vma is the last one with address > vma->vm_end. Have to extend vma. |
| 2160 | */ |
| 2161 | int expand_upwards(struct vm_area_struct *vma, unsigned long address) |
| 2162 | { |
| 2163 | struct vm_area_struct *next; |
| 2164 | unsigned long gap_addr; |
| 2165 | int error = 0; |
| 2166 | |
| 2167 | if (!(vma->vm_flags & VM_GROWSUP)) |
| 2168 | return -EFAULT; |
| 2169 | |
| 2170 | /* Guard against exceeding limits of the address space. */ |
| 2171 | address &= PAGE_MASK; |
| 2172 | if (address >= (TASK_SIZE & PAGE_MASK)) |
| 2173 | return -ENOMEM; |
| 2174 | address += PAGE_SIZE; |
| 2175 | |
| 2176 | /* Enforce stack_guard_gap */ |
| 2177 | gap_addr = address + stack_guard_gap; |
| 2178 | |
| 2179 | /* Guard against overflow */ |
| 2180 | if (gap_addr < address || gap_addr > TASK_SIZE) |
| 2181 | gap_addr = TASK_SIZE; |
| 2182 | |
| 2183 | next = vma->vm_next; |
| 2184 | if (next && next->vm_start < gap_addr) { |
| 2185 | if (!(next->vm_flags & VM_GROWSUP)) |
| 2186 | return -ENOMEM; |
| 2187 | /* Check that both stack segments have the same anon_vma? */ |
| 2188 | } |
| 2189 | |
| 2190 | /* We must make sure the anon_vma is allocated. */ |
| 2191 | if (unlikely(anon_vma_prepare(vma))) |
| 2192 | return -ENOMEM; |
| 2193 | |
| 2194 | /* Enforce stack_guard_gap */ |
| 2195 | gap_addr = address + stack_guard_gap; |
| 2196 | if (gap_addr < address) |
| 2197 | return -ENOMEM; |
| 2198 | next = vma->vm_next; |
| 2199 | if (next && next->vm_start < gap_addr) { |
| 2200 | if (!(next->vm_flags & VM_GROWSUP)) |
| 2201 | return -ENOMEM; |
| 2202 | /* Check that both stack segments have the same anon_vma? */ |
| 2203 | } |
| 2204 | |
| 2205 | /* We must make sure the anon_vma is allocated. */ |
| 2206 | if (unlikely(anon_vma_prepare(vma))) |
| 2207 | return -ENOMEM; |
| 2208 | |
| 2209 | /* |
| 2210 | * vma->vm_start/vm_end cannot change under us because the caller |
| 2211 | * is required to hold the mmap_sem in read mode. We need the |
| 2212 | * anon_vma lock to serialize against concurrent expand_stacks. |
| 2213 | */ |
| 2214 | vma_lock_anon_vma(vma); |
| 2215 | |
| 2216 | /* Somebody else might have raced and expanded it already */ |
| 2217 | if (address > vma->vm_end) { |
| 2218 | unsigned long size, grow; |
| 2219 | |
| 2220 | size = address - vma->vm_start; |
| 2221 | grow = (address - vma->vm_end) >> PAGE_SHIFT; |
| 2222 | |
| 2223 | error = -ENOMEM; |
| 2224 | if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { |
| 2225 | error = acct_stack_growth(vma, size, grow); |
| 2226 | if (!error) { |
| 2227 | /* |
| 2228 | * vma_gap_update() doesn't support concurrent |
| 2229 | * updates, but we only hold a shared mmap_sem |
| 2230 | * lock here, so we need to protect against |
| 2231 | * concurrent vma expansions. |
| 2232 | * vma_lock_anon_vma() doesn't help here, as |
| 2233 | * we don't guarantee that all growable vmas |
| 2234 | * in a mm share the same root anon vma. |
| 2235 | * So, we reuse mm->page_table_lock to guard |
| 2236 | * against concurrent vma expansions. |
| 2237 | */ |
| 2238 | spin_lock(&vma->vm_mm->page_table_lock); |
| 2239 | anon_vma_interval_tree_pre_update_vma(vma); |
| 2240 | vma->vm_end = address; |
| 2241 | anon_vma_interval_tree_post_update_vma(vma); |
| 2242 | if (vma->vm_next) |
| 2243 | vma_gap_update(vma->vm_next); |
| 2244 | else |
| 2245 | vma->vm_mm->highest_vm_end = vm_end_gap(vma); |
| 2246 | spin_unlock(&vma->vm_mm->page_table_lock); |
| 2247 | |
| 2248 | perf_event_mmap(vma); |
| 2249 | } |
| 2250 | } |
| 2251 | } |
| 2252 | vma_unlock_anon_vma(vma); |
| 2253 | khugepaged_enter_vma_merge(vma); |
| 2254 | validate_mm(vma->vm_mm); |
| 2255 | return error; |
| 2256 | } |
| 2257 | #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ |
| 2258 | |
| 2259 | /* |
| 2260 | * vma is the first one with address < vma->vm_start. Have to extend vma. |
| 2261 | */ |
| 2262 | int expand_downwards(struct vm_area_struct *vma, |
| 2263 | unsigned long address) |
| 2264 | { |
| 2265 | struct vm_area_struct *prev; |
| 2266 | unsigned long gap_addr; |
| 2267 | int error; |
| 2268 | |
| 2269 | address &= PAGE_MASK; |
| 2270 | error = security_mmap_addr(address); |
| 2271 | if (error) |
| 2272 | return error; |
| 2273 | |
| 2274 | /* Enforce stack_guard_gap */ |
| 2275 | gap_addr = address - stack_guard_gap; |
| 2276 | if (gap_addr > address) |
| 2277 | return -ENOMEM; |
| 2278 | prev = vma->vm_prev; |
| 2279 | if (prev && prev->vm_end > gap_addr) { |
| 2280 | if (!(prev->vm_flags & VM_GROWSDOWN)) |
| 2281 | return -ENOMEM; |
| 2282 | /* Check that both stack segments have the same anon_vma? */ |
| 2283 | } |
| 2284 | |
| 2285 | /* We must make sure the anon_vma is allocated. */ |
| 2286 | if (unlikely(anon_vma_prepare(vma))) |
| 2287 | return -ENOMEM; |
| 2288 | |
| 2289 | /* |
| 2290 | * vma->vm_start/vm_end cannot change under us because the caller |
| 2291 | * is required to hold the mmap_sem in read mode. We need the |
| 2292 | * anon_vma lock to serialize against concurrent expand_stacks. |
| 2293 | */ |
| 2294 | vma_lock_anon_vma(vma); |
| 2295 | |
| 2296 | /* Somebody else might have raced and expanded it already */ |
| 2297 | if (address < vma->vm_start) { |
| 2298 | unsigned long size, grow; |
| 2299 | |
| 2300 | size = vma->vm_end - address; |
| 2301 | grow = (vma->vm_start - address) >> PAGE_SHIFT; |
| 2302 | |
| 2303 | error = -ENOMEM; |
| 2304 | if (grow <= vma->vm_pgoff) { |
| 2305 | error = acct_stack_growth(vma, size, grow); |
| 2306 | if (!error) { |
| 2307 | /* |
| 2308 | * vma_gap_update() doesn't support concurrent |
| 2309 | * updates, but we only hold a shared mmap_sem |
| 2310 | * lock here, so we need to protect against |
| 2311 | * concurrent vma expansions. |
| 2312 | * vma_lock_anon_vma() doesn't help here, as |
| 2313 | * we don't guarantee that all growable vmas |
| 2314 | * in a mm share the same root anon vma. |
| 2315 | * So, we reuse mm->page_table_lock to guard |
| 2316 | * against concurrent vma expansions. |
| 2317 | */ |
| 2318 | spin_lock(&vma->vm_mm->page_table_lock); |
| 2319 | anon_vma_interval_tree_pre_update_vma(vma); |
| 2320 | vma->vm_start = address; |
| 2321 | vma->vm_pgoff -= grow; |
| 2322 | anon_vma_interval_tree_post_update_vma(vma); |
| 2323 | vma_gap_update(vma); |
| 2324 | spin_unlock(&vma->vm_mm->page_table_lock); |
| 2325 | |
| 2326 | perf_event_mmap(vma); |
| 2327 | } |
| 2328 | } |
| 2329 | } |
| 2330 | vma_unlock_anon_vma(vma); |
| 2331 | khugepaged_enter_vma_merge(vma); |
| 2332 | validate_mm(vma->vm_mm); |
| 2333 | return error; |
| 2334 | } |
| 2335 | |
| 2336 | /* enforced gap between the expanding stack and other mappings. */ |
| 2337 | unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; |
| 2338 | |
| 2339 | static int __init cmdline_parse_stack_guard_gap(char *p) |
| 2340 | { |
| 2341 | unsigned long val; |
| 2342 | char *endptr; |
| 2343 | |
| 2344 | val = simple_strtoul(p, &endptr, 10); |
| 2345 | if (!*endptr) |
| 2346 | stack_guard_gap = val << PAGE_SHIFT; |
| 2347 | |
| 2348 | return 0; |
| 2349 | } |
| 2350 | __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); |
| 2351 | |
| 2352 | #ifdef CONFIG_STACK_GROWSUP |
| 2353 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| 2354 | { |
| 2355 | return expand_upwards(vma, address); |
| 2356 | } |
| 2357 | |
| 2358 | struct vm_area_struct * |
| 2359 | find_extend_vma(struct mm_struct *mm, unsigned long addr) |
| 2360 | { |
| 2361 | struct vm_area_struct *vma, *prev; |
| 2362 | |
| 2363 | addr &= PAGE_MASK; |
| 2364 | vma = find_vma_prev(mm, addr, &prev); |
| 2365 | if (vma && (vma->vm_start <= addr)) |
| 2366 | return vma; |
| 2367 | if (!prev || expand_stack(prev, addr)) |
| 2368 | return NULL; |
| 2369 | if (prev->vm_flags & VM_LOCKED) |
| 2370 | __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL); |
| 2371 | return prev; |
| 2372 | } |
| 2373 | #else |
| 2374 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
| 2375 | { |
| 2376 | return expand_downwards(vma, address); |
| 2377 | } |
| 2378 | |
| 2379 | struct vm_area_struct * |
| 2380 | find_extend_vma(struct mm_struct * mm, unsigned long addr) |
| 2381 | { |
| 2382 | struct vm_area_struct * vma; |
| 2383 | unsigned long start; |
| 2384 | |
| 2385 | addr &= PAGE_MASK; |
| 2386 | vma = find_vma(mm,addr); |
| 2387 | if (!vma) |
| 2388 | return NULL; |
| 2389 | if (vma->vm_start <= addr) |
| 2390 | return vma; |
| 2391 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 2392 | return NULL; |
| 2393 | start = vma->vm_start; |
| 2394 | if (expand_stack(vma, addr)) |
| 2395 | return NULL; |
| 2396 | if (vma->vm_flags & VM_LOCKED) |
| 2397 | __mlock_vma_pages_range(vma, addr, start, NULL); |
| 2398 | return vma; |
| 2399 | } |
| 2400 | #endif |
| 2401 | |
| 2402 | /* |
| 2403 | * Ok - we have the memory areas we should free on the vma list, |
| 2404 | * so release them, and do the vma updates. |
| 2405 | * |
| 2406 | * Called with the mm semaphore held. |
| 2407 | */ |
| 2408 | static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) |
| 2409 | { |
| 2410 | unsigned long nr_accounted = 0; |
| 2411 | |
| 2412 | /* Update high watermark before we lower total_vm */ |
| 2413 | update_hiwater_vm(mm); |
| 2414 | do { |
| 2415 | long nrpages = vma_pages(vma); |
| 2416 | |
| 2417 | if (vma->vm_flags & VM_ACCOUNT) |
| 2418 | nr_accounted += nrpages; |
| 2419 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); |
| 2420 | vma = remove_vma(vma); |
| 2421 | } while (vma); |
| 2422 | vm_unacct_memory(nr_accounted); |
| 2423 | validate_mm(mm); |
| 2424 | } |
| 2425 | |
| 2426 | /* |
| 2427 | * Get rid of page table information in the indicated region. |
| 2428 | * |
| 2429 | * Called with the mm semaphore held. |
| 2430 | */ |
| 2431 | static void unmap_region(struct mm_struct *mm, |
| 2432 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
| 2433 | unsigned long start, unsigned long end) |
| 2434 | { |
| 2435 | struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; |
| 2436 | struct mmu_gather tlb; |
| 2437 | |
| 2438 | lru_add_drain(); |
| 2439 | tlb_gather_mmu(&tlb, mm, start, end); |
| 2440 | update_hiwater_rss(mm); |
| 2441 | unmap_vmas(&tlb, vma, start, end); |
| 2442 | free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, |
| 2443 | next ? next->vm_start : USER_PGTABLES_CEILING); |
| 2444 | tlb_finish_mmu(&tlb, start, end); |
| 2445 | } |
| 2446 | |
| 2447 | /* |
| 2448 | * Create a list of vma's touched by the unmap, removing them from the mm's |
| 2449 | * vma list as we go.. |
| 2450 | */ |
| 2451 | static void |
| 2452 | detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, |
| 2453 | struct vm_area_struct *prev, unsigned long end) |
| 2454 | { |
| 2455 | struct vm_area_struct **insertion_point; |
| 2456 | struct vm_area_struct *tail_vma = NULL; |
| 2457 | unsigned long addr; |
| 2458 | |
| 2459 | insertion_point = (prev ? &prev->vm_next : &mm->mmap); |
| 2460 | vma->vm_prev = NULL; |
| 2461 | do { |
| 2462 | vma_rb_erase(vma, &mm->mm_rb); |
| 2463 | mm->map_count--; |
| 2464 | tail_vma = vma; |
| 2465 | vma = vma->vm_next; |
| 2466 | } while (vma && vma->vm_start < end); |
| 2467 | *insertion_point = vma; |
| 2468 | if (vma) { |
| 2469 | vma->vm_prev = prev; |
| 2470 | vma_gap_update(vma); |
| 2471 | } else |
| 2472 | mm->highest_vm_end = prev ? vm_end_gap(prev) : 0; |
| 2473 | tail_vma->vm_next = NULL; |
| 2474 | if (mm->unmap_area == arch_unmap_area) |
| 2475 | addr = prev ? prev->vm_end : mm->mmap_base; |
| 2476 | else |
| 2477 | addr = vma ? vma->vm_start : mm->mmap_base; |
| 2478 | mm->unmap_area(mm, addr); |
| 2479 | |
| 2480 | /* Kill the cache */ |
| 2481 | vmacache_invalidate(mm); |
| 2482 | } |
| 2483 | |
| 2484 | /* |
| 2485 | * __split_vma() bypasses sysctl_max_map_count checking. We use this on the |
| 2486 | * munmap path where it doesn't make sense to fail. |
| 2487 | */ |
| 2488 | static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, |
| 2489 | unsigned long addr, int new_below) |
| 2490 | { |
| 2491 | struct vm_area_struct *new; |
| 2492 | int err = -ENOMEM; |
| 2493 | |
| 2494 | if (is_vm_hugetlb_page(vma) && (addr & |
| 2495 | ~(huge_page_mask(hstate_vma(vma))))) |
| 2496 | return -EINVAL; |
| 2497 | |
| 2498 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| 2499 | if (!new) |
| 2500 | goto out_err; |
| 2501 | |
| 2502 | /* most fields are the same, copy all, and then fixup */ |
| 2503 | *new = *vma; |
| 2504 | |
| 2505 | INIT_LIST_HEAD(&new->anon_vma_chain); |
| 2506 | |
| 2507 | if (new_below) |
| 2508 | new->vm_end = addr; |
| 2509 | else { |
| 2510 | new->vm_start = addr; |
| 2511 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); |
| 2512 | } |
| 2513 | |
| 2514 | err = vma_dup_policy(vma, new); |
| 2515 | if (err) |
| 2516 | goto out_free_vma; |
| 2517 | |
| 2518 | if (anon_vma_clone(new, vma)) |
| 2519 | goto out_free_mpol; |
| 2520 | |
| 2521 | if (new->vm_file) |
| 2522 | get_file(new->vm_file); |
| 2523 | |
| 2524 | if (new->vm_ops && new->vm_ops->open) |
| 2525 | new->vm_ops->open(new); |
| 2526 | |
| 2527 | if (new_below) |
| 2528 | err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + |
| 2529 | ((addr - new->vm_start) >> PAGE_SHIFT), new); |
| 2530 | else |
| 2531 | err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); |
| 2532 | |
| 2533 | /* Success. */ |
| 2534 | if (!err) |
| 2535 | return 0; |
| 2536 | |
| 2537 | /* Clean everything up if vma_adjust failed. */ |
| 2538 | if (new->vm_ops && new->vm_ops->close) |
| 2539 | new->vm_ops->close(new); |
| 2540 | if (new->vm_file) |
| 2541 | fput(new->vm_file); |
| 2542 | unlink_anon_vmas(new); |
| 2543 | out_free_mpol: |
| 2544 | mpol_put(vma_policy(new)); |
| 2545 | out_free_vma: |
| 2546 | kmem_cache_free(vm_area_cachep, new); |
| 2547 | out_err: |
| 2548 | return err; |
| 2549 | } |
| 2550 | |
| 2551 | /* |
| 2552 | * Split a vma into two pieces at address 'addr', a new vma is allocated |
| 2553 | * either for the first part or the tail. |
| 2554 | */ |
| 2555 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, |
| 2556 | unsigned long addr, int new_below) |
| 2557 | { |
| 2558 | if (mm->map_count >= sysctl_max_map_count) |
| 2559 | return -ENOMEM; |
| 2560 | |
| 2561 | return __split_vma(mm, vma, addr, new_below); |
| 2562 | } |
| 2563 | |
| 2564 | /* Munmap is split into 2 main parts -- this part which finds |
| 2565 | * what needs doing, and the areas themselves, which do the |
| 2566 | * work. This now handles partial unmappings. |
| 2567 | * Jeremy Fitzhardinge <jeremy@goop.org> |
| 2568 | */ |
| 2569 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) |
| 2570 | { |
| 2571 | unsigned long end; |
| 2572 | struct vm_area_struct *vma, *prev, *last; |
| 2573 | |
| 2574 | if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) |
| 2575 | return -EINVAL; |
| 2576 | |
| 2577 | if ((len = PAGE_ALIGN(len)) == 0) |
| 2578 | return -EINVAL; |
| 2579 | |
| 2580 | /* Find the first overlapping VMA */ |
| 2581 | vma = find_vma(mm, start); |
| 2582 | if (!vma) |
| 2583 | return 0; |
| 2584 | prev = vma->vm_prev; |
| 2585 | /* we have start < vma->vm_end */ |
| 2586 | |
| 2587 | /* if it doesn't overlap, we have nothing.. */ |
| 2588 | end = start + len; |
| 2589 | if (vma->vm_start >= end) |
| 2590 | return 0; |
| 2591 | |
| 2592 | /* |
| 2593 | * If we need to split any vma, do it now to save pain later. |
| 2594 | * |
| 2595 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially |
| 2596 | * unmapped vm_area_struct will remain in use: so lower split_vma |
| 2597 | * places tmp vma above, and higher split_vma places tmp vma below. |
| 2598 | */ |
| 2599 | if (start > vma->vm_start) { |
| 2600 | int error; |
| 2601 | |
| 2602 | /* |
| 2603 | * Make sure that map_count on return from munmap() will |
| 2604 | * not exceed its limit; but let map_count go just above |
| 2605 | * its limit temporarily, to help free resources as expected. |
| 2606 | */ |
| 2607 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) |
| 2608 | return -ENOMEM; |
| 2609 | |
| 2610 | error = __split_vma(mm, vma, start, 0); |
| 2611 | if (error) |
| 2612 | return error; |
| 2613 | prev = vma; |
| 2614 | } |
| 2615 | |
| 2616 | /* Does it split the last one? */ |
| 2617 | last = find_vma(mm, end); |
| 2618 | if (last && end > last->vm_start) { |
| 2619 | int error = __split_vma(mm, last, end, 1); |
| 2620 | if (error) |
| 2621 | return error; |
| 2622 | } |
| 2623 | vma = prev? prev->vm_next: mm->mmap; |
| 2624 | |
| 2625 | /* |
| 2626 | * unlock any mlock()ed ranges before detaching vmas |
| 2627 | */ |
| 2628 | if (mm->locked_vm) { |
| 2629 | struct vm_area_struct *tmp = vma; |
| 2630 | while (tmp && tmp->vm_start < end) { |
| 2631 | if (tmp->vm_flags & VM_LOCKED) { |
| 2632 | mm->locked_vm -= vma_pages(tmp); |
| 2633 | munlock_vma_pages_all(tmp); |
| 2634 | } |
| 2635 | tmp = tmp->vm_next; |
| 2636 | } |
| 2637 | } |
| 2638 | |
| 2639 | /* |
| 2640 | * Remove the vma's, and unmap the actual pages |
| 2641 | */ |
| 2642 | detach_vmas_to_be_unmapped(mm, vma, prev, end); |
| 2643 | unmap_region(mm, vma, prev, start, end); |
| 2644 | |
| 2645 | /* Fix up all other VM information */ |
| 2646 | remove_vma_list(mm, vma); |
| 2647 | |
| 2648 | return 0; |
| 2649 | } |
| 2650 | |
| 2651 | int vm_munmap(unsigned long start, size_t len) |
| 2652 | { |
| 2653 | int ret; |
| 2654 | struct mm_struct *mm = current->mm; |
| 2655 | |
| 2656 | down_write(&mm->mmap_sem); |
| 2657 | ret = do_munmap(mm, start, len); |
| 2658 | up_write(&mm->mmap_sem); |
| 2659 | return ret; |
| 2660 | } |
| 2661 | EXPORT_SYMBOL(vm_munmap); |
| 2662 | |
| 2663 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
| 2664 | { |
| 2665 | profile_munmap(addr); |
| 2666 | return vm_munmap(addr, len); |
| 2667 | } |
| 2668 | |
| 2669 | static inline void verify_mm_writelocked(struct mm_struct *mm) |
| 2670 | { |
| 2671 | #ifdef CONFIG_DEBUG_VM |
| 2672 | if (unlikely(down_read_trylock(&mm->mmap_sem))) { |
| 2673 | WARN_ON(1); |
| 2674 | up_read(&mm->mmap_sem); |
| 2675 | } |
| 2676 | #endif |
| 2677 | } |
| 2678 | |
| 2679 | /* |
| 2680 | * this is really a simplified "do_mmap". it only handles |
| 2681 | * anonymous maps. eventually we may be able to do some |
| 2682 | * brk-specific accounting here. |
| 2683 | */ |
| 2684 | static unsigned long do_brk(unsigned long addr, unsigned long len) |
| 2685 | { |
| 2686 | struct mm_struct * mm = current->mm; |
| 2687 | struct vm_area_struct * vma, * prev; |
| 2688 | unsigned long flags; |
| 2689 | struct rb_node ** rb_link, * rb_parent; |
| 2690 | pgoff_t pgoff = addr >> PAGE_SHIFT; |
| 2691 | int error; |
| 2692 | |
| 2693 | len = PAGE_ALIGN(len); |
| 2694 | if (!len) |
| 2695 | return addr; |
| 2696 | |
| 2697 | flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; |
| 2698 | |
| 2699 | error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); |
| 2700 | if (error & ~PAGE_MASK) |
| 2701 | return error; |
| 2702 | |
| 2703 | /* |
| 2704 | * mlock MCL_FUTURE? |
| 2705 | */ |
| 2706 | if (mm->def_flags & VM_LOCKED) { |
| 2707 | unsigned long locked, lock_limit; |
| 2708 | locked = len >> PAGE_SHIFT; |
| 2709 | locked += mm->locked_vm; |
| 2710 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
| 2711 | lock_limit >>= PAGE_SHIFT; |
| 2712 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
| 2713 | return -EAGAIN; |
| 2714 | } |
| 2715 | |
| 2716 | /* |
| 2717 | * mm->mmap_sem is required to protect against another thread |
| 2718 | * changing the mappings in case we sleep. |
| 2719 | */ |
| 2720 | verify_mm_writelocked(mm); |
| 2721 | |
| 2722 | /* |
| 2723 | * Clear old maps. this also does some error checking for us |
| 2724 | */ |
| 2725 | munmap_back: |
| 2726 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { |
| 2727 | if (do_munmap(mm, addr, len)) |
| 2728 | return -ENOMEM; |
| 2729 | goto munmap_back; |
| 2730 | } |
| 2731 | |
| 2732 | /* Check against address space limits *after* clearing old maps... */ |
| 2733 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) |
| 2734 | return -ENOMEM; |
| 2735 | |
| 2736 | if (mm->map_count > sysctl_max_map_count) |
| 2737 | return -ENOMEM; |
| 2738 | |
| 2739 | if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) |
| 2740 | return -ENOMEM; |
| 2741 | |
| 2742 | /* Can we just expand an old private anonymous mapping? */ |
| 2743 | vma = vma_merge(mm, prev, addr, addr + len, flags, |
| 2744 | NULL, NULL, pgoff, NULL, NULL); |
| 2745 | if (vma) |
| 2746 | goto out; |
| 2747 | |
| 2748 | /* |
| 2749 | * create a vma struct for an anonymous mapping |
| 2750 | */ |
| 2751 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| 2752 | if (!vma) { |
| 2753 | vm_unacct_memory(len >> PAGE_SHIFT); |
| 2754 | return -ENOMEM; |
| 2755 | } |
| 2756 | |
| 2757 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
| 2758 | vma->vm_mm = mm; |
| 2759 | vma->vm_start = addr; |
| 2760 | vma->vm_end = addr + len; |
| 2761 | vma->vm_pgoff = pgoff; |
| 2762 | vma->vm_flags = flags; |
| 2763 | vma->vm_page_prot = vm_get_page_prot(flags); |
| 2764 | vma_link(mm, vma, prev, rb_link, rb_parent); |
| 2765 | out: |
| 2766 | perf_event_mmap(vma); |
| 2767 | mm->total_vm += len >> PAGE_SHIFT; |
| 2768 | if (flags & VM_LOCKED) |
| 2769 | mm->locked_vm += (len >> PAGE_SHIFT); |
| 2770 | return addr; |
| 2771 | } |
| 2772 | |
| 2773 | unsigned long vm_brk(unsigned long addr, unsigned long len) |
| 2774 | { |
| 2775 | struct mm_struct *mm = current->mm; |
| 2776 | unsigned long ret; |
| 2777 | bool populate; |
| 2778 | |
| 2779 | down_write(&mm->mmap_sem); |
| 2780 | ret = do_brk(addr, len); |
| 2781 | populate = ((mm->def_flags & VM_LOCKED) != 0); |
| 2782 | up_write(&mm->mmap_sem); |
| 2783 | if (populate) |
| 2784 | mm_populate(addr, len); |
| 2785 | return ret; |
| 2786 | } |
| 2787 | EXPORT_SYMBOL(vm_brk); |
| 2788 | |
| 2789 | /* Release all mmaps. */ |
| 2790 | void exit_mmap(struct mm_struct *mm) |
| 2791 | { |
| 2792 | struct mmu_gather tlb; |
| 2793 | struct vm_area_struct *vma; |
| 2794 | unsigned long nr_accounted = 0; |
| 2795 | |
| 2796 | /* mm's last user has gone, and its about to be pulled down */ |
| 2797 | mmu_notifier_release(mm); |
| 2798 | |
| 2799 | if (mm->locked_vm) { |
| 2800 | vma = mm->mmap; |
| 2801 | while (vma) { |
| 2802 | if (vma->vm_flags & VM_LOCKED) |
| 2803 | munlock_vma_pages_all(vma); |
| 2804 | vma = vma->vm_next; |
| 2805 | } |
| 2806 | } |
| 2807 | |
| 2808 | arch_exit_mmap(mm); |
| 2809 | |
| 2810 | vma = mm->mmap; |
| 2811 | if (!vma) /* Can happen if dup_mmap() received an OOM */ |
| 2812 | return; |
| 2813 | |
| 2814 | lru_add_drain(); |
| 2815 | flush_cache_mm(mm); |
| 2816 | tlb_gather_mmu(&tlb, mm, 0, -1); |
| 2817 | /* update_hiwater_rss(mm) here? but nobody should be looking */ |
| 2818 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ |
| 2819 | unmap_vmas(&tlb, vma, 0, -1); |
| 2820 | |
| 2821 | free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); |
| 2822 | tlb_finish_mmu(&tlb, 0, -1); |
| 2823 | |
| 2824 | /* |
| 2825 | * Walk the list again, actually closing and freeing it, |
| 2826 | * with preemption enabled, without holding any MM locks. |
| 2827 | */ |
| 2828 | while (vma) { |
| 2829 | if (vma->vm_flags & VM_ACCOUNT) |
| 2830 | nr_accounted += vma_pages(vma); |
| 2831 | vma = remove_vma(vma); |
| 2832 | } |
| 2833 | vm_unacct_memory(nr_accounted); |
| 2834 | |
| 2835 | WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); |
| 2836 | } |
| 2837 | |
| 2838 | /* Insert vm structure into process list sorted by address |
| 2839 | * and into the inode's i_mmap tree. If vm_file is non-NULL |
| 2840 | * then i_mmap_mutex is taken here. |
| 2841 | */ |
| 2842 | int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| 2843 | { |
| 2844 | struct vm_area_struct *prev; |
| 2845 | struct rb_node **rb_link, *rb_parent; |
| 2846 | |
| 2847 | /* |
| 2848 | * The vm_pgoff of a purely anonymous vma should be irrelevant |
| 2849 | * until its first write fault, when page's anon_vma and index |
| 2850 | * are set. But now set the vm_pgoff it will almost certainly |
| 2851 | * end up with (unless mremap moves it elsewhere before that |
| 2852 | * first wfault), so /proc/pid/maps tells a consistent story. |
| 2853 | * |
| 2854 | * By setting it to reflect the virtual start address of the |
| 2855 | * vma, merges and splits can happen in a seamless way, just |
| 2856 | * using the existing file pgoff checks and manipulations. |
| 2857 | * Similarly in do_mmap_pgoff and in do_brk. |
| 2858 | */ |
| 2859 | if (!vma->vm_file) { |
| 2860 | BUG_ON(vma->anon_vma); |
| 2861 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
| 2862 | } |
| 2863 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, |
| 2864 | &prev, &rb_link, &rb_parent)) |
| 2865 | return -ENOMEM; |
| 2866 | if ((vma->vm_flags & VM_ACCOUNT) && |
| 2867 | security_vm_enough_memory_mm(mm, vma_pages(vma))) |
| 2868 | return -ENOMEM; |
| 2869 | |
| 2870 | vma_link(mm, vma, prev, rb_link, rb_parent); |
| 2871 | return 0; |
| 2872 | } |
| 2873 | |
| 2874 | /* |
| 2875 | * Copy the vma structure to a new location in the same mm, |
| 2876 | * prior to moving page table entries, to effect an mremap move. |
| 2877 | */ |
| 2878 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, |
| 2879 | unsigned long addr, unsigned long len, pgoff_t pgoff, |
| 2880 | bool *need_rmap_locks) |
| 2881 | { |
| 2882 | struct vm_area_struct *vma = *vmap; |
| 2883 | unsigned long vma_start = vma->vm_start; |
| 2884 | struct mm_struct *mm = vma->vm_mm; |
| 2885 | struct vm_area_struct *new_vma, *prev; |
| 2886 | struct rb_node **rb_link, *rb_parent; |
| 2887 | bool faulted_in_anon_vma = true; |
| 2888 | |
| 2889 | /* |
| 2890 | * If anonymous vma has not yet been faulted, update new pgoff |
| 2891 | * to match new location, to increase its chance of merging. |
| 2892 | */ |
| 2893 | if (unlikely(!vma->vm_file && !vma->anon_vma)) { |
| 2894 | pgoff = addr >> PAGE_SHIFT; |
| 2895 | faulted_in_anon_vma = false; |
| 2896 | } |
| 2897 | |
| 2898 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) |
| 2899 | return NULL; /* should never get here */ |
| 2900 | new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, |
| 2901 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), |
| 2902 | vma_get_anon_name(vma)); |
| 2903 | if (new_vma) { |
| 2904 | /* |
| 2905 | * Source vma may have been merged into new_vma |
| 2906 | */ |
| 2907 | if (unlikely(vma_start >= new_vma->vm_start && |
| 2908 | vma_start < new_vma->vm_end)) { |
| 2909 | /* |
| 2910 | * The only way we can get a vma_merge with |
| 2911 | * self during an mremap is if the vma hasn't |
| 2912 | * been faulted in yet and we were allowed to |
| 2913 | * reset the dst vma->vm_pgoff to the |
| 2914 | * destination address of the mremap to allow |
| 2915 | * the merge to happen. mremap must change the |
| 2916 | * vm_pgoff linearity between src and dst vmas |
| 2917 | * (in turn preventing a vma_merge) to be |
| 2918 | * safe. It is only safe to keep the vm_pgoff |
| 2919 | * linear if there are no pages mapped yet. |
| 2920 | */ |
| 2921 | VM_BUG_ON(faulted_in_anon_vma); |
| 2922 | *vmap = vma = new_vma; |
| 2923 | } |
| 2924 | *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); |
| 2925 | } else { |
| 2926 | new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| 2927 | if (new_vma) { |
| 2928 | *new_vma = *vma; |
| 2929 | new_vma->vm_start = addr; |
| 2930 | new_vma->vm_end = addr + len; |
| 2931 | new_vma->vm_pgoff = pgoff; |
| 2932 | if (vma_dup_policy(vma, new_vma)) |
| 2933 | goto out_free_vma; |
| 2934 | INIT_LIST_HEAD(&new_vma->anon_vma_chain); |
| 2935 | if (anon_vma_clone(new_vma, vma)) |
| 2936 | goto out_free_mempol; |
| 2937 | if (new_vma->vm_file) |
| 2938 | get_file(new_vma->vm_file); |
| 2939 | if (new_vma->vm_ops && new_vma->vm_ops->open) |
| 2940 | new_vma->vm_ops->open(new_vma); |
| 2941 | vma_link(mm, new_vma, prev, rb_link, rb_parent); |
| 2942 | *need_rmap_locks = false; |
| 2943 | } |
| 2944 | } |
| 2945 | return new_vma; |
| 2946 | |
| 2947 | out_free_mempol: |
| 2948 | mpol_put(vma_policy(new_vma)); |
| 2949 | out_free_vma: |
| 2950 | kmem_cache_free(vm_area_cachep, new_vma); |
| 2951 | return NULL; |
| 2952 | } |
| 2953 | |
| 2954 | /* |
| 2955 | * Return true if the calling process may expand its vm space by the passed |
| 2956 | * number of pages |
| 2957 | */ |
| 2958 | int may_expand_vm(struct mm_struct *mm, unsigned long npages) |
| 2959 | { |
| 2960 | unsigned long cur = mm->total_vm; /* pages */ |
| 2961 | unsigned long lim; |
| 2962 | |
| 2963 | lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT; |
| 2964 | |
| 2965 | if (cur + npages > lim) |
| 2966 | return 0; |
| 2967 | return 1; |
| 2968 | } |
| 2969 | |
| 2970 | |
| 2971 | static int special_mapping_fault(struct vm_area_struct *vma, |
| 2972 | struct vm_fault *vmf) |
| 2973 | { |
| 2974 | pgoff_t pgoff; |
| 2975 | struct page **pages; |
| 2976 | |
| 2977 | /* |
| 2978 | * special mappings have no vm_file, and in that case, the mm |
| 2979 | * uses vm_pgoff internally. So we have to subtract it from here. |
| 2980 | * We are allowed to do this because we are the mm; do not copy |
| 2981 | * this code into drivers! |
| 2982 | */ |
| 2983 | pgoff = vmf->pgoff - vma->vm_pgoff; |
| 2984 | |
| 2985 | for (pages = vma->vm_private_data; pgoff && *pages; ++pages) |
| 2986 | pgoff--; |
| 2987 | |
| 2988 | if (*pages) { |
| 2989 | struct page *page = *pages; |
| 2990 | get_page(page); |
| 2991 | vmf->page = page; |
| 2992 | return 0; |
| 2993 | } |
| 2994 | |
| 2995 | return VM_FAULT_SIGBUS; |
| 2996 | } |
| 2997 | |
| 2998 | /* |
| 2999 | * Having a close hook prevents vma merging regardless of flags. |
| 3000 | */ |
| 3001 | static void special_mapping_close(struct vm_area_struct *vma) |
| 3002 | { |
| 3003 | } |
| 3004 | |
| 3005 | static const struct vm_operations_struct special_mapping_vmops = { |
| 3006 | .close = special_mapping_close, |
| 3007 | .fault = special_mapping_fault, |
| 3008 | }; |
| 3009 | |
| 3010 | /* |
| 3011 | * Called with mm->mmap_sem held for writing. |
| 3012 | * Insert a new vma covering the given region, with the given flags. |
| 3013 | * Its pages are supplied by the given array of struct page *. |
| 3014 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. |
| 3015 | * The region past the last page supplied will always produce SIGBUS. |
| 3016 | * The array pointer and the pages it points to are assumed to stay alive |
| 3017 | * for as long as this mapping might exist. |
| 3018 | */ |
| 3019 | int install_special_mapping(struct mm_struct *mm, |
| 3020 | unsigned long addr, unsigned long len, |
| 3021 | unsigned long vm_flags, struct page **pages) |
| 3022 | { |
| 3023 | int ret; |
| 3024 | struct vm_area_struct *vma; |
| 3025 | |
| 3026 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| 3027 | if (unlikely(vma == NULL)) |
| 3028 | return -ENOMEM; |
| 3029 | |
| 3030 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
| 3031 | vma->vm_mm = mm; |
| 3032 | vma->vm_start = addr; |
| 3033 | vma->vm_end = addr + len; |
| 3034 | |
| 3035 | vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; |
| 3036 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| 3037 | |
| 3038 | vma->vm_ops = &special_mapping_vmops; |
| 3039 | vma->vm_private_data = pages; |
| 3040 | |
| 3041 | ret = insert_vm_struct(mm, vma); |
| 3042 | if (ret) |
| 3043 | goto out; |
| 3044 | |
| 3045 | mm->total_vm += len >> PAGE_SHIFT; |
| 3046 | |
| 3047 | perf_event_mmap(vma); |
| 3048 | |
| 3049 | return 0; |
| 3050 | |
| 3051 | out: |
| 3052 | kmem_cache_free(vm_area_cachep, vma); |
| 3053 | return ret; |
| 3054 | } |
| 3055 | |
| 3056 | static DEFINE_MUTEX(mm_all_locks_mutex); |
| 3057 | |
| 3058 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) |
| 3059 | { |
| 3060 | if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { |
| 3061 | /* |
| 3062 | * The LSB of head.next can't change from under us |
| 3063 | * because we hold the mm_all_locks_mutex. |
| 3064 | */ |
| 3065 | down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); |
| 3066 | /* |
| 3067 | * We can safely modify head.next after taking the |
| 3068 | * anon_vma->root->rwsem. If some other vma in this mm shares |
| 3069 | * the same anon_vma we won't take it again. |
| 3070 | * |
| 3071 | * No need of atomic instructions here, head.next |
| 3072 | * can't change from under us thanks to the |
| 3073 | * anon_vma->root->rwsem. |
| 3074 | */ |
| 3075 | if (__test_and_set_bit(0, (unsigned long *) |
| 3076 | &anon_vma->root->rb_root.rb_node)) |
| 3077 | BUG(); |
| 3078 | } |
| 3079 | } |
| 3080 | |
| 3081 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) |
| 3082 | { |
| 3083 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| 3084 | /* |
| 3085 | * AS_MM_ALL_LOCKS can't change from under us because |
| 3086 | * we hold the mm_all_locks_mutex. |
| 3087 | * |
| 3088 | * Operations on ->flags have to be atomic because |
| 3089 | * even if AS_MM_ALL_LOCKS is stable thanks to the |
| 3090 | * mm_all_locks_mutex, there may be other cpus |
| 3091 | * changing other bitflags in parallel to us. |
| 3092 | */ |
| 3093 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) |
| 3094 | BUG(); |
| 3095 | mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem); |
| 3096 | } |
| 3097 | } |
| 3098 | |
| 3099 | /* |
| 3100 | * This operation locks against the VM for all pte/vma/mm related |
| 3101 | * operations that could ever happen on a certain mm. This includes |
| 3102 | * vmtruncate, try_to_unmap, and all page faults. |
| 3103 | * |
| 3104 | * The caller must take the mmap_sem in write mode before calling |
| 3105 | * mm_take_all_locks(). The caller isn't allowed to release the |
| 3106 | * mmap_sem until mm_drop_all_locks() returns. |
| 3107 | * |
| 3108 | * mmap_sem in write mode is required in order to block all operations |
| 3109 | * that could modify pagetables and free pages without need of |
| 3110 | * altering the vma layout (for example populate_range() with |
| 3111 | * nonlinear vmas). It's also needed in write mode to avoid new |
| 3112 | * anon_vmas to be associated with existing vmas. |
| 3113 | * |
| 3114 | * A single task can't take more than one mm_take_all_locks() in a row |
| 3115 | * or it would deadlock. |
| 3116 | * |
| 3117 | * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in |
| 3118 | * mapping->flags avoid to take the same lock twice, if more than one |
| 3119 | * vma in this mm is backed by the same anon_vma or address_space. |
| 3120 | * |
| 3121 | * We can take all the locks in random order because the VM code |
| 3122 | * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never |
| 3123 | * takes more than one of them in a row. Secondly we're protected |
| 3124 | * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. |
| 3125 | * |
| 3126 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations |
| 3127 | * that may have to take thousand of locks. |
| 3128 | * |
| 3129 | * mm_take_all_locks() can fail if it's interrupted by signals. |
| 3130 | */ |
| 3131 | int mm_take_all_locks(struct mm_struct *mm) |
| 3132 | { |
| 3133 | struct vm_area_struct *vma; |
| 3134 | struct anon_vma_chain *avc; |
| 3135 | |
| 3136 | BUG_ON(down_read_trylock(&mm->mmap_sem)); |
| 3137 | |
| 3138 | mutex_lock(&mm_all_locks_mutex); |
| 3139 | |
| 3140 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| 3141 | if (signal_pending(current)) |
| 3142 | goto out_unlock; |
| 3143 | if (vma->vm_file && vma->vm_file->f_mapping) |
| 3144 | vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| 3145 | } |
| 3146 | |
| 3147 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| 3148 | if (signal_pending(current)) |
| 3149 | goto out_unlock; |
| 3150 | if (vma->anon_vma) |
| 3151 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 3152 | vm_lock_anon_vma(mm, avc->anon_vma); |
| 3153 | } |
| 3154 | |
| 3155 | return 0; |
| 3156 | |
| 3157 | out_unlock: |
| 3158 | mm_drop_all_locks(mm); |
| 3159 | return -EINTR; |
| 3160 | } |
| 3161 | |
| 3162 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) |
| 3163 | { |
| 3164 | if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { |
| 3165 | /* |
| 3166 | * The LSB of head.next can't change to 0 from under |
| 3167 | * us because we hold the mm_all_locks_mutex. |
| 3168 | * |
| 3169 | * We must however clear the bitflag before unlocking |
| 3170 | * the vma so the users using the anon_vma->rb_root will |
| 3171 | * never see our bitflag. |
| 3172 | * |
| 3173 | * No need of atomic instructions here, head.next |
| 3174 | * can't change from under us until we release the |
| 3175 | * anon_vma->root->rwsem. |
| 3176 | */ |
| 3177 | if (!__test_and_clear_bit(0, (unsigned long *) |
| 3178 | &anon_vma->root->rb_root.rb_node)) |
| 3179 | BUG(); |
| 3180 | anon_vma_unlock_write(anon_vma); |
| 3181 | } |
| 3182 | } |
| 3183 | |
| 3184 | static void vm_unlock_mapping(struct address_space *mapping) |
| 3185 | { |
| 3186 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| 3187 | /* |
| 3188 | * AS_MM_ALL_LOCKS can't change to 0 from under us |
| 3189 | * because we hold the mm_all_locks_mutex. |
| 3190 | */ |
| 3191 | mutex_unlock(&mapping->i_mmap_mutex); |
| 3192 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, |
| 3193 | &mapping->flags)) |
| 3194 | BUG(); |
| 3195 | } |
| 3196 | } |
| 3197 | |
| 3198 | /* |
| 3199 | * The mmap_sem cannot be released by the caller until |
| 3200 | * mm_drop_all_locks() returns. |
| 3201 | */ |
| 3202 | void mm_drop_all_locks(struct mm_struct *mm) |
| 3203 | { |
| 3204 | struct vm_area_struct *vma; |
| 3205 | struct anon_vma_chain *avc; |
| 3206 | |
| 3207 | BUG_ON(down_read_trylock(&mm->mmap_sem)); |
| 3208 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); |
| 3209 | |
| 3210 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| 3211 | if (vma->anon_vma) |
| 3212 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| 3213 | vm_unlock_anon_vma(avc->anon_vma); |
| 3214 | if (vma->vm_file && vma->vm_file->f_mapping) |
| 3215 | vm_unlock_mapping(vma->vm_file->f_mapping); |
| 3216 | } |
| 3217 | |
| 3218 | mutex_unlock(&mm_all_locks_mutex); |
| 3219 | } |
| 3220 | |
| 3221 | /* |
| 3222 | * initialise the VMA slab |
| 3223 | */ |
| 3224 | void __init mmap_init(void) |
| 3225 | { |
| 3226 | int ret; |
| 3227 | |
| 3228 | ret = percpu_counter_init(&vm_committed_as, 0); |
| 3229 | VM_BUG_ON(ret); |
| 3230 | } |
| 3231 | |
| 3232 | /* |
| 3233 | * Initialise sysctl_user_reserve_kbytes. |
| 3234 | * |
| 3235 | * This is intended to prevent a user from starting a single memory hogging |
| 3236 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
| 3237 | * mode. |
| 3238 | * |
| 3239 | * The default value is min(3% of free memory, 128MB) |
| 3240 | * 128MB is enough to recover with sshd/login, bash, and top/kill. |
| 3241 | */ |
| 3242 | static int init_user_reserve(void) |
| 3243 | { |
| 3244 | unsigned long free_kbytes; |
| 3245 | |
| 3246 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| 3247 | |
| 3248 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
| 3249 | return 0; |
| 3250 | } |
| 3251 | module_init(init_user_reserve) |
| 3252 | |
| 3253 | /* |
| 3254 | * Initialise sysctl_admin_reserve_kbytes. |
| 3255 | * |
| 3256 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
| 3257 | * to log in and kill a memory hogging process. |
| 3258 | * |
| 3259 | * Systems with more than 256MB will reserve 8MB, enough to recover |
| 3260 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
| 3261 | * only reserve 3% of free pages by default. |
| 3262 | */ |
| 3263 | static int init_admin_reserve(void) |
| 3264 | { |
| 3265 | unsigned long free_kbytes; |
| 3266 | |
| 3267 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| 3268 | |
| 3269 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
| 3270 | return 0; |
| 3271 | } |
| 3272 | module_init(init_admin_reserve) |
| 3273 | |
| 3274 | /* |
| 3275 | * Reinititalise user and admin reserves if memory is added or removed. |
| 3276 | * |
| 3277 | * The default user reserve max is 128MB, and the default max for the |
| 3278 | * admin reserve is 8MB. These are usually, but not always, enough to |
| 3279 | * enable recovery from a memory hogging process using login/sshd, a shell, |
| 3280 | * and tools like top. It may make sense to increase or even disable the |
| 3281 | * reserve depending on the existence of swap or variations in the recovery |
| 3282 | * tools. So, the admin may have changed them. |
| 3283 | * |
| 3284 | * If memory is added and the reserves have been eliminated or increased above |
| 3285 | * the default max, then we'll trust the admin. |
| 3286 | * |
| 3287 | * If memory is removed and there isn't enough free memory, then we |
| 3288 | * need to reset the reserves. |
| 3289 | * |
| 3290 | * Otherwise keep the reserve set by the admin. |
| 3291 | */ |
| 3292 | static int reserve_mem_notifier(struct notifier_block *nb, |
| 3293 | unsigned long action, void *data) |
| 3294 | { |
| 3295 | unsigned long tmp, free_kbytes; |
| 3296 | |
| 3297 | switch (action) { |
| 3298 | case MEM_ONLINE: |
| 3299 | /* Default max is 128MB. Leave alone if modified by operator. */ |
| 3300 | tmp = sysctl_user_reserve_kbytes; |
| 3301 | if (0 < tmp && tmp < (1UL << 17)) |
| 3302 | init_user_reserve(); |
| 3303 | |
| 3304 | /* Default max is 8MB. Leave alone if modified by operator. */ |
| 3305 | tmp = sysctl_admin_reserve_kbytes; |
| 3306 | if (0 < tmp && tmp < (1UL << 13)) |
| 3307 | init_admin_reserve(); |
| 3308 | |
| 3309 | break; |
| 3310 | case MEM_OFFLINE: |
| 3311 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
| 3312 | |
| 3313 | if (sysctl_user_reserve_kbytes > free_kbytes) { |
| 3314 | init_user_reserve(); |
| 3315 | pr_info("vm.user_reserve_kbytes reset to %lu\n", |
| 3316 | sysctl_user_reserve_kbytes); |
| 3317 | } |
| 3318 | |
| 3319 | if (sysctl_admin_reserve_kbytes > free_kbytes) { |
| 3320 | init_admin_reserve(); |
| 3321 | pr_info("vm.admin_reserve_kbytes reset to %lu\n", |
| 3322 | sysctl_admin_reserve_kbytes); |
| 3323 | } |
| 3324 | break; |
| 3325 | default: |
| 3326 | break; |
| 3327 | } |
| 3328 | return NOTIFY_OK; |
| 3329 | } |
| 3330 | |
| 3331 | static struct notifier_block reserve_mem_nb = { |
| 3332 | .notifier_call = reserve_mem_notifier, |
| 3333 | }; |
| 3334 | |
| 3335 | static int __meminit init_reserve_notifier(void) |
| 3336 | { |
| 3337 | if (register_hotmemory_notifier(&reserve_mem_nb)) |
| 3338 | printk("Failed registering memory add/remove notifier for admin reserve"); |
| 3339 | |
| 3340 | return 0; |
| 3341 | } |
| 3342 | module_init(init_reserve_notifier) |