| 1 | /* |
| 2 | * linux/mm/memory.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * demand-loading started 01.12.91 - seems it is high on the list of |
| 9 | * things wanted, and it should be easy to implement. - Linus |
| 10 | */ |
| 11 | |
| 12 | /* |
| 13 | * Ok, demand-loading was easy, shared pages a little bit tricker. Shared |
| 14 | * pages started 02.12.91, seems to work. - Linus. |
| 15 | * |
| 16 | * Tested sharing by executing about 30 /bin/sh: under the old kernel it |
| 17 | * would have taken more than the 6M I have free, but it worked well as |
| 18 | * far as I could see. |
| 19 | * |
| 20 | * Also corrected some "invalidate()"s - I wasn't doing enough of them. |
| 21 | */ |
| 22 | |
| 23 | /* |
| 24 | * Real VM (paging to/from disk) started 18.12.91. Much more work and |
| 25 | * thought has to go into this. Oh, well.. |
| 26 | * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. |
| 27 | * Found it. Everything seems to work now. |
| 28 | * 20.12.91 - Ok, making the swap-device changeable like the root. |
| 29 | */ |
| 30 | |
| 31 | /* |
| 32 | * 05.04.94 - Multi-page memory management added for v1.1. |
| 33 | * Idea by Alex Bligh (alex@cconcepts.co.uk) |
| 34 | * |
| 35 | * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG |
| 36 | * (Gerhard.Wichert@pdb.siemens.de) |
| 37 | * |
| 38 | * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) |
| 39 | */ |
| 40 | |
| 41 | #include <linux/kernel_stat.h> |
| 42 | #include <linux/mm.h> |
| 43 | #include <linux/hugetlb.h> |
| 44 | #include <linux/mman.h> |
| 45 | #include <linux/swap.h> |
| 46 | #include <linux/highmem.h> |
| 47 | #include <linux/pagemap.h> |
| 48 | #include <linux/ksm.h> |
| 49 | #include <linux/rmap.h> |
| 50 | #include <linux/export.h> |
| 51 | #include <linux/delayacct.h> |
| 52 | #include <linux/init.h> |
| 53 | #include <linux/writeback.h> |
| 54 | #include <linux/memcontrol.h> |
| 55 | #include <linux/mmu_notifier.h> |
| 56 | #include <linux/kallsyms.h> |
| 57 | #include <linux/swapops.h> |
| 58 | #include <linux/elf.h> |
| 59 | #include <linux/gfp.h> |
| 60 | #include <linux/migrate.h> |
| 61 | #include <linux/string.h> |
| 62 | #include <linux/dma-debug.h> |
| 63 | #include <linux/debugfs.h> |
| 64 | |
| 65 | #include <asm/io.h> |
| 66 | #include <asm/pgalloc.h> |
| 67 | #include <asm/uaccess.h> |
| 68 | #include <asm/tlb.h> |
| 69 | #include <asm/tlbflush.h> |
| 70 | #include <asm/pgtable.h> |
| 71 | |
| 72 | #include "internal.h" |
| 73 | |
| 74 | #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS |
| 75 | #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. |
| 76 | #endif |
| 77 | |
| 78 | #ifndef CONFIG_NEED_MULTIPLE_NODES |
| 79 | /* use the per-pgdat data instead for discontigmem - mbligh */ |
| 80 | unsigned long max_mapnr; |
| 81 | struct page *mem_map; |
| 82 | |
| 83 | EXPORT_SYMBOL(max_mapnr); |
| 84 | EXPORT_SYMBOL(mem_map); |
| 85 | #endif |
| 86 | |
| 87 | /* |
| 88 | * A number of key systems in x86 including ioremap() rely on the assumption |
| 89 | * that high_memory defines the upper bound on direct map memory, then end |
| 90 | * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and |
| 91 | * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL |
| 92 | * and ZONE_HIGHMEM. |
| 93 | */ |
| 94 | void * high_memory; |
| 95 | |
| 96 | EXPORT_SYMBOL(high_memory); |
| 97 | |
| 98 | /* |
| 99 | * Randomize the address space (stacks, mmaps, brk, etc.). |
| 100 | * |
| 101 | * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
| 102 | * as ancient (libc5 based) binaries can segfault. ) |
| 103 | */ |
| 104 | int randomize_va_space __read_mostly = |
| 105 | #ifdef CONFIG_COMPAT_BRK |
| 106 | 1; |
| 107 | #else |
| 108 | 2; |
| 109 | #endif |
| 110 | |
| 111 | static int __init disable_randmaps(char *s) |
| 112 | { |
| 113 | randomize_va_space = 0; |
| 114 | return 1; |
| 115 | } |
| 116 | __setup("norandmaps", disable_randmaps); |
| 117 | |
| 118 | unsigned long zero_pfn __read_mostly; |
| 119 | unsigned long highest_memmap_pfn __read_mostly; |
| 120 | |
| 121 | /* |
| 122 | * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
| 123 | */ |
| 124 | static int __init init_zero_pfn(void) |
| 125 | { |
| 126 | zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
| 127 | return 0; |
| 128 | } |
| 129 | core_initcall(init_zero_pfn); |
| 130 | |
| 131 | |
| 132 | #if defined(SPLIT_RSS_COUNTING) |
| 133 | |
| 134 | void sync_mm_rss(struct mm_struct *mm) |
| 135 | { |
| 136 | int i; |
| 137 | |
| 138 | for (i = 0; i < NR_MM_COUNTERS; i++) { |
| 139 | if (current->rss_stat.count[i]) { |
| 140 | add_mm_counter(mm, i, current->rss_stat.count[i]); |
| 141 | current->rss_stat.count[i] = 0; |
| 142 | } |
| 143 | } |
| 144 | current->rss_stat.events = 0; |
| 145 | } |
| 146 | |
| 147 | static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) |
| 148 | { |
| 149 | struct task_struct *task = current; |
| 150 | |
| 151 | if (likely(task->mm == mm)) |
| 152 | task->rss_stat.count[member] += val; |
| 153 | else |
| 154 | add_mm_counter(mm, member, val); |
| 155 | } |
| 156 | #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) |
| 157 | #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) |
| 158 | |
| 159 | /* sync counter once per 64 page faults */ |
| 160 | #define TASK_RSS_EVENTS_THRESH (64) |
| 161 | static void check_sync_rss_stat(struct task_struct *task) |
| 162 | { |
| 163 | if (unlikely(task != current)) |
| 164 | return; |
| 165 | if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) |
| 166 | sync_mm_rss(task->mm); |
| 167 | } |
| 168 | #else /* SPLIT_RSS_COUNTING */ |
| 169 | |
| 170 | #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) |
| 171 | #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) |
| 172 | |
| 173 | static void check_sync_rss_stat(struct task_struct *task) |
| 174 | { |
| 175 | } |
| 176 | |
| 177 | #endif /* SPLIT_RSS_COUNTING */ |
| 178 | |
| 179 | #ifdef HAVE_GENERIC_MMU_GATHER |
| 180 | |
| 181 | static int tlb_next_batch(struct mmu_gather *tlb) |
| 182 | { |
| 183 | struct mmu_gather_batch *batch; |
| 184 | |
| 185 | batch = tlb->active; |
| 186 | if (batch->next) { |
| 187 | tlb->active = batch->next; |
| 188 | return 1; |
| 189 | } |
| 190 | |
| 191 | if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) |
| 192 | return 0; |
| 193 | |
| 194 | batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); |
| 195 | if (!batch) |
| 196 | return 0; |
| 197 | |
| 198 | tlb->batch_count++; |
| 199 | batch->next = NULL; |
| 200 | batch->nr = 0; |
| 201 | batch->max = MAX_GATHER_BATCH; |
| 202 | |
| 203 | tlb->active->next = batch; |
| 204 | tlb->active = batch; |
| 205 | |
| 206 | return 1; |
| 207 | } |
| 208 | |
| 209 | /* tlb_gather_mmu |
| 210 | * Called to initialize an (on-stack) mmu_gather structure for page-table |
| 211 | * tear-down from @mm. The @fullmm argument is used when @mm is without |
| 212 | * users and we're going to destroy the full address space (exit/execve). |
| 213 | */ |
| 214 | void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) |
| 215 | { |
| 216 | tlb->mm = mm; |
| 217 | |
| 218 | /* Is it from 0 to ~0? */ |
| 219 | tlb->fullmm = !(start | (end+1)); |
| 220 | tlb->need_flush_all = 0; |
| 221 | tlb->start = start; |
| 222 | tlb->end = end; |
| 223 | tlb->need_flush = 0; |
| 224 | tlb->local.next = NULL; |
| 225 | tlb->local.nr = 0; |
| 226 | tlb->local.max = ARRAY_SIZE(tlb->__pages); |
| 227 | tlb->active = &tlb->local; |
| 228 | tlb->batch_count = 0; |
| 229 | |
| 230 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
| 231 | tlb->batch = NULL; |
| 232 | #endif |
| 233 | } |
| 234 | |
| 235 | static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) |
| 236 | { |
| 237 | tlb->need_flush = 0; |
| 238 | tlb_flush(tlb); |
| 239 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
| 240 | tlb_table_flush(tlb); |
| 241 | #endif |
| 242 | } |
| 243 | |
| 244 | static void tlb_flush_mmu_free(struct mmu_gather *tlb) |
| 245 | { |
| 246 | struct mmu_gather_batch *batch; |
| 247 | |
| 248 | for (batch = &tlb->local; batch; batch = batch->next) { |
| 249 | free_pages_and_swap_cache(batch->pages, batch->nr); |
| 250 | batch->nr = 0; |
| 251 | } |
| 252 | tlb->active = &tlb->local; |
| 253 | } |
| 254 | |
| 255 | void tlb_flush_mmu(struct mmu_gather *tlb) |
| 256 | { |
| 257 | if (!tlb->need_flush) |
| 258 | return; |
| 259 | tlb_flush_mmu_tlbonly(tlb); |
| 260 | tlb_flush_mmu_free(tlb); |
| 261 | } |
| 262 | |
| 263 | /* tlb_finish_mmu |
| 264 | * Called at the end of the shootdown operation to free up any resources |
| 265 | * that were required. |
| 266 | */ |
| 267 | void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) |
| 268 | { |
| 269 | struct mmu_gather_batch *batch, *next; |
| 270 | |
| 271 | tlb_flush_mmu(tlb); |
| 272 | |
| 273 | /* keep the page table cache within bounds */ |
| 274 | check_pgt_cache(); |
| 275 | |
| 276 | for (batch = tlb->local.next; batch; batch = next) { |
| 277 | next = batch->next; |
| 278 | free_pages((unsigned long)batch, 0); |
| 279 | } |
| 280 | tlb->local.next = NULL; |
| 281 | } |
| 282 | |
| 283 | /* __tlb_remove_page |
| 284 | * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while |
| 285 | * handling the additional races in SMP caused by other CPUs caching valid |
| 286 | * mappings in their TLBs. Returns the number of free page slots left. |
| 287 | * When out of page slots we must call tlb_flush_mmu(). |
| 288 | */ |
| 289 | int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) |
| 290 | { |
| 291 | struct mmu_gather_batch *batch; |
| 292 | |
| 293 | VM_BUG_ON(!tlb->need_flush); |
| 294 | |
| 295 | batch = tlb->active; |
| 296 | batch->pages[batch->nr++] = page; |
| 297 | if (batch->nr == batch->max) { |
| 298 | if (!tlb_next_batch(tlb)) |
| 299 | return 0; |
| 300 | batch = tlb->active; |
| 301 | } |
| 302 | VM_BUG_ON_PAGE(batch->nr > batch->max, page); |
| 303 | |
| 304 | return batch->max - batch->nr; |
| 305 | } |
| 306 | |
| 307 | #endif /* HAVE_GENERIC_MMU_GATHER */ |
| 308 | |
| 309 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
| 310 | |
| 311 | /* |
| 312 | * See the comment near struct mmu_table_batch. |
| 313 | */ |
| 314 | |
| 315 | static void tlb_remove_table_smp_sync(void *arg) |
| 316 | { |
| 317 | /* Simply deliver the interrupt */ |
| 318 | } |
| 319 | |
| 320 | static void tlb_remove_table_one(void *table) |
| 321 | { |
| 322 | /* |
| 323 | * This isn't an RCU grace period and hence the page-tables cannot be |
| 324 | * assumed to be actually RCU-freed. |
| 325 | * |
| 326 | * It is however sufficient for software page-table walkers that rely on |
| 327 | * IRQ disabling. See the comment near struct mmu_table_batch. |
| 328 | */ |
| 329 | smp_call_function(tlb_remove_table_smp_sync, NULL, 1); |
| 330 | __tlb_remove_table(table); |
| 331 | } |
| 332 | |
| 333 | static void tlb_remove_table_rcu(struct rcu_head *head) |
| 334 | { |
| 335 | struct mmu_table_batch *batch; |
| 336 | int i; |
| 337 | |
| 338 | batch = container_of(head, struct mmu_table_batch, rcu); |
| 339 | |
| 340 | for (i = 0; i < batch->nr; i++) |
| 341 | __tlb_remove_table(batch->tables[i]); |
| 342 | |
| 343 | free_page((unsigned long)batch); |
| 344 | } |
| 345 | |
| 346 | void tlb_table_flush(struct mmu_gather *tlb) |
| 347 | { |
| 348 | struct mmu_table_batch **batch = &tlb->batch; |
| 349 | |
| 350 | if (*batch) { |
| 351 | call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); |
| 352 | *batch = NULL; |
| 353 | } |
| 354 | } |
| 355 | |
| 356 | void tlb_remove_table(struct mmu_gather *tlb, void *table) |
| 357 | { |
| 358 | struct mmu_table_batch **batch = &tlb->batch; |
| 359 | |
| 360 | tlb->need_flush = 1; |
| 361 | |
| 362 | /* |
| 363 | * When there's less then two users of this mm there cannot be a |
| 364 | * concurrent page-table walk. |
| 365 | */ |
| 366 | if (atomic_read(&tlb->mm->mm_users) < 2) { |
| 367 | __tlb_remove_table(table); |
| 368 | return; |
| 369 | } |
| 370 | |
| 371 | if (*batch == NULL) { |
| 372 | *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); |
| 373 | if (*batch == NULL) { |
| 374 | tlb_remove_table_one(table); |
| 375 | return; |
| 376 | } |
| 377 | (*batch)->nr = 0; |
| 378 | } |
| 379 | (*batch)->tables[(*batch)->nr++] = table; |
| 380 | if ((*batch)->nr == MAX_TABLE_BATCH) |
| 381 | tlb_table_flush(tlb); |
| 382 | } |
| 383 | |
| 384 | #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ |
| 385 | |
| 386 | /* |
| 387 | * Note: this doesn't free the actual pages themselves. That |
| 388 | * has been handled earlier when unmapping all the memory regions. |
| 389 | */ |
| 390 | static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
| 391 | unsigned long addr) |
| 392 | { |
| 393 | pgtable_t token = pmd_pgtable(*pmd); |
| 394 | pmd_clear(pmd); |
| 395 | pte_free_tlb(tlb, token, addr); |
| 396 | atomic_long_dec(&tlb->mm->nr_ptes); |
| 397 | } |
| 398 | |
| 399 | static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
| 400 | unsigned long addr, unsigned long end, |
| 401 | unsigned long floor, unsigned long ceiling) |
| 402 | { |
| 403 | pmd_t *pmd; |
| 404 | unsigned long next; |
| 405 | unsigned long start; |
| 406 | |
| 407 | start = addr; |
| 408 | pmd = pmd_offset(pud, addr); |
| 409 | do { |
| 410 | next = pmd_addr_end(addr, end); |
| 411 | if (pmd_none_or_clear_bad(pmd)) |
| 412 | continue; |
| 413 | free_pte_range(tlb, pmd, addr); |
| 414 | } while (pmd++, addr = next, addr != end); |
| 415 | |
| 416 | start &= PUD_MASK; |
| 417 | if (start < floor) |
| 418 | return; |
| 419 | if (ceiling) { |
| 420 | ceiling &= PUD_MASK; |
| 421 | if (!ceiling) |
| 422 | return; |
| 423 | } |
| 424 | if (end - 1 > ceiling - 1) |
| 425 | return; |
| 426 | |
| 427 | pmd = pmd_offset(pud, start); |
| 428 | pud_clear(pud); |
| 429 | pmd_free_tlb(tlb, pmd, start); |
| 430 | } |
| 431 | |
| 432 | static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, |
| 433 | unsigned long addr, unsigned long end, |
| 434 | unsigned long floor, unsigned long ceiling) |
| 435 | { |
| 436 | pud_t *pud; |
| 437 | unsigned long next; |
| 438 | unsigned long start; |
| 439 | |
| 440 | start = addr; |
| 441 | pud = pud_offset(pgd, addr); |
| 442 | do { |
| 443 | next = pud_addr_end(addr, end); |
| 444 | if (pud_none_or_clear_bad(pud)) |
| 445 | continue; |
| 446 | free_pmd_range(tlb, pud, addr, next, floor, ceiling); |
| 447 | } while (pud++, addr = next, addr != end); |
| 448 | |
| 449 | start &= PGDIR_MASK; |
| 450 | if (start < floor) |
| 451 | return; |
| 452 | if (ceiling) { |
| 453 | ceiling &= PGDIR_MASK; |
| 454 | if (!ceiling) |
| 455 | return; |
| 456 | } |
| 457 | if (end - 1 > ceiling - 1) |
| 458 | return; |
| 459 | |
| 460 | pud = pud_offset(pgd, start); |
| 461 | pgd_clear(pgd); |
| 462 | pud_free_tlb(tlb, pud, start); |
| 463 | } |
| 464 | |
| 465 | /* |
| 466 | * This function frees user-level page tables of a process. |
| 467 | */ |
| 468 | void free_pgd_range(struct mmu_gather *tlb, |
| 469 | unsigned long addr, unsigned long end, |
| 470 | unsigned long floor, unsigned long ceiling) |
| 471 | { |
| 472 | pgd_t *pgd; |
| 473 | unsigned long next; |
| 474 | |
| 475 | /* |
| 476 | * The next few lines have given us lots of grief... |
| 477 | * |
| 478 | * Why are we testing PMD* at this top level? Because often |
| 479 | * there will be no work to do at all, and we'd prefer not to |
| 480 | * go all the way down to the bottom just to discover that. |
| 481 | * |
| 482 | * Why all these "- 1"s? Because 0 represents both the bottom |
| 483 | * of the address space and the top of it (using -1 for the |
| 484 | * top wouldn't help much: the masks would do the wrong thing). |
| 485 | * The rule is that addr 0 and floor 0 refer to the bottom of |
| 486 | * the address space, but end 0 and ceiling 0 refer to the top |
| 487 | * Comparisons need to use "end - 1" and "ceiling - 1" (though |
| 488 | * that end 0 case should be mythical). |
| 489 | * |
| 490 | * Wherever addr is brought up or ceiling brought down, we must |
| 491 | * be careful to reject "the opposite 0" before it confuses the |
| 492 | * subsequent tests. But what about where end is brought down |
| 493 | * by PMD_SIZE below? no, end can't go down to 0 there. |
| 494 | * |
| 495 | * Whereas we round start (addr) and ceiling down, by different |
| 496 | * masks at different levels, in order to test whether a table |
| 497 | * now has no other vmas using it, so can be freed, we don't |
| 498 | * bother to round floor or end up - the tests don't need that. |
| 499 | */ |
| 500 | |
| 501 | addr &= PMD_MASK; |
| 502 | if (addr < floor) { |
| 503 | addr += PMD_SIZE; |
| 504 | if (!addr) |
| 505 | return; |
| 506 | } |
| 507 | if (ceiling) { |
| 508 | ceiling &= PMD_MASK; |
| 509 | if (!ceiling) |
| 510 | return; |
| 511 | } |
| 512 | if (end - 1 > ceiling - 1) |
| 513 | end -= PMD_SIZE; |
| 514 | if (addr > end - 1) |
| 515 | return; |
| 516 | |
| 517 | pgd = pgd_offset(tlb->mm, addr); |
| 518 | do { |
| 519 | next = pgd_addr_end(addr, end); |
| 520 | if (pgd_none_or_clear_bad(pgd)) |
| 521 | continue; |
| 522 | free_pud_range(tlb, pgd, addr, next, floor, ceiling); |
| 523 | } while (pgd++, addr = next, addr != end); |
| 524 | } |
| 525 | |
| 526 | void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, |
| 527 | unsigned long floor, unsigned long ceiling) |
| 528 | { |
| 529 | while (vma) { |
| 530 | struct vm_area_struct *next = vma->vm_next; |
| 531 | unsigned long addr = vma->vm_start; |
| 532 | |
| 533 | /* |
| 534 | * Hide vma from rmap and truncate_pagecache before freeing |
| 535 | * pgtables |
| 536 | */ |
| 537 | unlink_anon_vmas(vma); |
| 538 | unlink_file_vma(vma); |
| 539 | |
| 540 | if (is_vm_hugetlb_page(vma)) { |
| 541 | hugetlb_free_pgd_range(tlb, addr, vma->vm_end, |
| 542 | floor, next? next->vm_start: ceiling); |
| 543 | } else { |
| 544 | /* |
| 545 | * Optimization: gather nearby vmas into one call down |
| 546 | */ |
| 547 | while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
| 548 | && !is_vm_hugetlb_page(next)) { |
| 549 | vma = next; |
| 550 | next = vma->vm_next; |
| 551 | unlink_anon_vmas(vma); |
| 552 | unlink_file_vma(vma); |
| 553 | } |
| 554 | free_pgd_range(tlb, addr, vma->vm_end, |
| 555 | floor, next? next->vm_start: ceiling); |
| 556 | } |
| 557 | vma = next; |
| 558 | } |
| 559 | } |
| 560 | |
| 561 | int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, |
| 562 | pmd_t *pmd, unsigned long address) |
| 563 | { |
| 564 | spinlock_t *ptl; |
| 565 | pgtable_t new = pte_alloc_one(mm, address); |
| 566 | int wait_split_huge_page; |
| 567 | if (!new) |
| 568 | return -ENOMEM; |
| 569 | |
| 570 | /* |
| 571 | * Ensure all pte setup (eg. pte page lock and page clearing) are |
| 572 | * visible before the pte is made visible to other CPUs by being |
| 573 | * put into page tables. |
| 574 | * |
| 575 | * The other side of the story is the pointer chasing in the page |
| 576 | * table walking code (when walking the page table without locking; |
| 577 | * ie. most of the time). Fortunately, these data accesses consist |
| 578 | * of a chain of data-dependent loads, meaning most CPUs (alpha |
| 579 | * being the notable exception) will already guarantee loads are |
| 580 | * seen in-order. See the alpha page table accessors for the |
| 581 | * smp_read_barrier_depends() barriers in page table walking code. |
| 582 | */ |
| 583 | smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
| 584 | |
| 585 | ptl = pmd_lock(mm, pmd); |
| 586 | wait_split_huge_page = 0; |
| 587 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| 588 | atomic_long_inc(&mm->nr_ptes); |
| 589 | pmd_populate(mm, pmd, new); |
| 590 | new = NULL; |
| 591 | } else if (unlikely(pmd_trans_splitting(*pmd))) |
| 592 | wait_split_huge_page = 1; |
| 593 | spin_unlock(ptl); |
| 594 | if (new) |
| 595 | pte_free(mm, new); |
| 596 | if (wait_split_huge_page) |
| 597 | wait_split_huge_page(vma->anon_vma, pmd); |
| 598 | return 0; |
| 599 | } |
| 600 | |
| 601 | int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) |
| 602 | { |
| 603 | pte_t *new = pte_alloc_one_kernel(&init_mm, address); |
| 604 | if (!new) |
| 605 | return -ENOMEM; |
| 606 | |
| 607 | smp_wmb(); /* See comment in __pte_alloc */ |
| 608 | |
| 609 | spin_lock(&init_mm.page_table_lock); |
| 610 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| 611 | pmd_populate_kernel(&init_mm, pmd, new); |
| 612 | new = NULL; |
| 613 | } else |
| 614 | VM_BUG_ON(pmd_trans_splitting(*pmd)); |
| 615 | spin_unlock(&init_mm.page_table_lock); |
| 616 | if (new) |
| 617 | pte_free_kernel(&init_mm, new); |
| 618 | return 0; |
| 619 | } |
| 620 | |
| 621 | static inline void init_rss_vec(int *rss) |
| 622 | { |
| 623 | memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); |
| 624 | } |
| 625 | |
| 626 | static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) |
| 627 | { |
| 628 | int i; |
| 629 | |
| 630 | if (current->mm == mm) |
| 631 | sync_mm_rss(mm); |
| 632 | for (i = 0; i < NR_MM_COUNTERS; i++) |
| 633 | if (rss[i]) |
| 634 | add_mm_counter(mm, i, rss[i]); |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * This function is called to print an error when a bad pte |
| 639 | * is found. For example, we might have a PFN-mapped pte in |
| 640 | * a region that doesn't allow it. |
| 641 | * |
| 642 | * The calling function must still handle the error. |
| 643 | */ |
| 644 | static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
| 645 | pte_t pte, struct page *page) |
| 646 | { |
| 647 | pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
| 648 | pud_t *pud = pud_offset(pgd, addr); |
| 649 | pmd_t *pmd = pmd_offset(pud, addr); |
| 650 | struct address_space *mapping; |
| 651 | pgoff_t index; |
| 652 | static unsigned long resume; |
| 653 | static unsigned long nr_shown; |
| 654 | static unsigned long nr_unshown; |
| 655 | |
| 656 | /* |
| 657 | * Allow a burst of 60 reports, then keep quiet for that minute; |
| 658 | * or allow a steady drip of one report per second. |
| 659 | */ |
| 660 | if (nr_shown == 60) { |
| 661 | if (time_before(jiffies, resume)) { |
| 662 | nr_unshown++; |
| 663 | return; |
| 664 | } |
| 665 | if (nr_unshown) { |
| 666 | printk(KERN_ALERT |
| 667 | "BUG: Bad page map: %lu messages suppressed\n", |
| 668 | nr_unshown); |
| 669 | nr_unshown = 0; |
| 670 | } |
| 671 | nr_shown = 0; |
| 672 | } |
| 673 | if (nr_shown++ == 0) |
| 674 | resume = jiffies + 60 * HZ; |
| 675 | |
| 676 | mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
| 677 | index = linear_page_index(vma, addr); |
| 678 | |
| 679 | printk(KERN_ALERT |
| 680 | "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", |
| 681 | current->comm, |
| 682 | (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
| 683 | if (page) |
| 684 | dump_page(page, "bad pte"); |
| 685 | printk(KERN_ALERT |
| 686 | "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", |
| 687 | (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
| 688 | /* |
| 689 | * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y |
| 690 | */ |
| 691 | if (vma->vm_ops) |
| 692 | printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", |
| 693 | vma->vm_ops->fault); |
| 694 | if (vma->vm_file) |
| 695 | printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", |
| 696 | vma->vm_file->f_op->mmap); |
| 697 | dump_stack(); |
| 698 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
| 699 | } |
| 700 | |
| 701 | static inline bool is_cow_mapping(vm_flags_t flags) |
| 702 | { |
| 703 | return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; |
| 704 | } |
| 705 | |
| 706 | /* |
| 707 | * vm_normal_page -- This function gets the "struct page" associated with a pte. |
| 708 | * |
| 709 | * "Special" mappings do not wish to be associated with a "struct page" (either |
| 710 | * it doesn't exist, or it exists but they don't want to touch it). In this |
| 711 | * case, NULL is returned here. "Normal" mappings do have a struct page. |
| 712 | * |
| 713 | * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
| 714 | * pte bit, in which case this function is trivial. Secondly, an architecture |
| 715 | * may not have a spare pte bit, which requires a more complicated scheme, |
| 716 | * described below. |
| 717 | * |
| 718 | * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
| 719 | * special mapping (even if there are underlying and valid "struct pages"). |
| 720 | * COWed pages of a VM_PFNMAP are always normal. |
| 721 | * |
| 722 | * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
| 723 | * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
| 724 | * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
| 725 | * mapping will always honor the rule |
| 726 | * |
| 727 | * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
| 728 | * |
| 729 | * And for normal mappings this is false. |
| 730 | * |
| 731 | * This restricts such mappings to be a linear translation from virtual address |
| 732 | * to pfn. To get around this restriction, we allow arbitrary mappings so long |
| 733 | * as the vma is not a COW mapping; in that case, we know that all ptes are |
| 734 | * special (because none can have been COWed). |
| 735 | * |
| 736 | * |
| 737 | * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
| 738 | * |
| 739 | * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
| 740 | * page" backing, however the difference is that _all_ pages with a struct |
| 741 | * page (that is, those where pfn_valid is true) are refcounted and considered |
| 742 | * normal pages by the VM. The disadvantage is that pages are refcounted |
| 743 | * (which can be slower and simply not an option for some PFNMAP users). The |
| 744 | * advantage is that we don't have to follow the strict linearity rule of |
| 745 | * PFNMAP mappings in order to support COWable mappings. |
| 746 | * |
| 747 | */ |
| 748 | #ifdef __HAVE_ARCH_PTE_SPECIAL |
| 749 | # define HAVE_PTE_SPECIAL 1 |
| 750 | #else |
| 751 | # define HAVE_PTE_SPECIAL 0 |
| 752 | #endif |
| 753 | struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
| 754 | pte_t pte) |
| 755 | { |
| 756 | unsigned long pfn = pte_pfn(pte); |
| 757 | |
| 758 | if (HAVE_PTE_SPECIAL) { |
| 759 | if (likely(!pte_special(pte))) |
| 760 | goto check_pfn; |
| 761 | if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| 762 | return NULL; |
| 763 | if (!is_zero_pfn(pfn)) |
| 764 | print_bad_pte(vma, addr, pte, NULL); |
| 765 | return NULL; |
| 766 | } |
| 767 | |
| 768 | /* !HAVE_PTE_SPECIAL case follows: */ |
| 769 | |
| 770 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| 771 | if (vma->vm_flags & VM_MIXEDMAP) { |
| 772 | if (!pfn_valid(pfn)) |
| 773 | return NULL; |
| 774 | goto out; |
| 775 | } else { |
| 776 | unsigned long off; |
| 777 | off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| 778 | if (pfn == vma->vm_pgoff + off) |
| 779 | return NULL; |
| 780 | if (!is_cow_mapping(vma->vm_flags)) |
| 781 | return NULL; |
| 782 | } |
| 783 | } |
| 784 | |
| 785 | if (is_zero_pfn(pfn)) |
| 786 | return NULL; |
| 787 | check_pfn: |
| 788 | if (unlikely(pfn > highest_memmap_pfn)) { |
| 789 | print_bad_pte(vma, addr, pte, NULL); |
| 790 | return NULL; |
| 791 | } |
| 792 | |
| 793 | /* |
| 794 | * NOTE! We still have PageReserved() pages in the page tables. |
| 795 | * eg. VDSO mappings can cause them to exist. |
| 796 | */ |
| 797 | out: |
| 798 | return pfn_to_page(pfn); |
| 799 | } |
| 800 | |
| 801 | /* |
| 802 | * copy one vm_area from one task to the other. Assumes the page tables |
| 803 | * already present in the new task to be cleared in the whole range |
| 804 | * covered by this vma. |
| 805 | */ |
| 806 | |
| 807 | static inline unsigned long |
| 808 | copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| 809 | pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, |
| 810 | unsigned long addr, int *rss) |
| 811 | { |
| 812 | unsigned long vm_flags = vma->vm_flags; |
| 813 | pte_t pte = *src_pte; |
| 814 | struct page *page; |
| 815 | |
| 816 | /* pte contains position in swap or file, so copy. */ |
| 817 | if (unlikely(!pte_present(pte))) { |
| 818 | if (!pte_file(pte)) { |
| 819 | swp_entry_t entry = pte_to_swp_entry(pte); |
| 820 | |
| 821 | if (swap_duplicate(entry) < 0) |
| 822 | return entry.val; |
| 823 | |
| 824 | /* make sure dst_mm is on swapoff's mmlist. */ |
| 825 | if (unlikely(list_empty(&dst_mm->mmlist))) { |
| 826 | spin_lock(&mmlist_lock); |
| 827 | if (list_empty(&dst_mm->mmlist)) |
| 828 | list_add(&dst_mm->mmlist, |
| 829 | &src_mm->mmlist); |
| 830 | spin_unlock(&mmlist_lock); |
| 831 | } |
| 832 | if (likely(!non_swap_entry(entry))) |
| 833 | rss[MM_SWAPENTS]++; |
| 834 | else if (is_migration_entry(entry)) { |
| 835 | page = migration_entry_to_page(entry); |
| 836 | |
| 837 | if (PageAnon(page)) |
| 838 | rss[MM_ANONPAGES]++; |
| 839 | else |
| 840 | rss[MM_FILEPAGES]++; |
| 841 | |
| 842 | if (is_write_migration_entry(entry) && |
| 843 | is_cow_mapping(vm_flags)) { |
| 844 | /* |
| 845 | * COW mappings require pages in both |
| 846 | * parent and child to be set to read. |
| 847 | */ |
| 848 | make_migration_entry_read(&entry); |
| 849 | pte = swp_entry_to_pte(entry); |
| 850 | if (pte_swp_soft_dirty(*src_pte)) |
| 851 | pte = pte_swp_mksoft_dirty(pte); |
| 852 | set_pte_at(src_mm, addr, src_pte, pte); |
| 853 | } |
| 854 | } |
| 855 | } |
| 856 | goto out_set_pte; |
| 857 | } |
| 858 | |
| 859 | /* |
| 860 | * If it's a COW mapping, write protect it both |
| 861 | * in the parent and the child |
| 862 | */ |
| 863 | if (is_cow_mapping(vm_flags)) { |
| 864 | ptep_set_wrprotect(src_mm, addr, src_pte); |
| 865 | pte = pte_wrprotect(pte); |
| 866 | } |
| 867 | |
| 868 | /* |
| 869 | * If it's a shared mapping, mark it clean in |
| 870 | * the child |
| 871 | */ |
| 872 | if (vm_flags & VM_SHARED) |
| 873 | pte = pte_mkclean(pte); |
| 874 | pte = pte_mkold(pte); |
| 875 | |
| 876 | page = vm_normal_page(vma, addr, pte); |
| 877 | if (page) { |
| 878 | get_page(page); |
| 879 | page_dup_rmap(page); |
| 880 | if (PageAnon(page)) |
| 881 | rss[MM_ANONPAGES]++; |
| 882 | else |
| 883 | rss[MM_FILEPAGES]++; |
| 884 | } |
| 885 | |
| 886 | out_set_pte: |
| 887 | set_pte_at(dst_mm, addr, dst_pte, pte); |
| 888 | return 0; |
| 889 | } |
| 890 | |
| 891 | int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| 892 | pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, |
| 893 | unsigned long addr, unsigned long end) |
| 894 | { |
| 895 | pte_t *orig_src_pte, *orig_dst_pte; |
| 896 | pte_t *src_pte, *dst_pte; |
| 897 | spinlock_t *src_ptl, *dst_ptl; |
| 898 | int progress = 0; |
| 899 | int rss[NR_MM_COUNTERS]; |
| 900 | swp_entry_t entry = (swp_entry_t){0}; |
| 901 | |
| 902 | again: |
| 903 | init_rss_vec(rss); |
| 904 | |
| 905 | dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
| 906 | if (!dst_pte) |
| 907 | return -ENOMEM; |
| 908 | src_pte = pte_offset_map(src_pmd, addr); |
| 909 | src_ptl = pte_lockptr(src_mm, src_pmd); |
| 910 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
| 911 | orig_src_pte = src_pte; |
| 912 | orig_dst_pte = dst_pte; |
| 913 | arch_enter_lazy_mmu_mode(); |
| 914 | |
| 915 | do { |
| 916 | /* |
| 917 | * We are holding two locks at this point - either of them |
| 918 | * could generate latencies in another task on another CPU. |
| 919 | */ |
| 920 | if (progress >= 32) { |
| 921 | progress = 0; |
| 922 | if (need_resched() || |
| 923 | spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) |
| 924 | break; |
| 925 | } |
| 926 | if (pte_none(*src_pte)) { |
| 927 | progress++; |
| 928 | continue; |
| 929 | } |
| 930 | entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, |
| 931 | vma, addr, rss); |
| 932 | if (entry.val) |
| 933 | break; |
| 934 | progress += 8; |
| 935 | } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
| 936 | |
| 937 | arch_leave_lazy_mmu_mode(); |
| 938 | spin_unlock(src_ptl); |
| 939 | pte_unmap(orig_src_pte); |
| 940 | add_mm_rss_vec(dst_mm, rss); |
| 941 | pte_unmap_unlock(orig_dst_pte, dst_ptl); |
| 942 | cond_resched(); |
| 943 | |
| 944 | if (entry.val) { |
| 945 | if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) |
| 946 | return -ENOMEM; |
| 947 | progress = 0; |
| 948 | } |
| 949 | if (addr != end) |
| 950 | goto again; |
| 951 | return 0; |
| 952 | } |
| 953 | |
| 954 | static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| 955 | pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, |
| 956 | unsigned long addr, unsigned long end) |
| 957 | { |
| 958 | pmd_t *src_pmd, *dst_pmd; |
| 959 | unsigned long next; |
| 960 | |
| 961 | dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); |
| 962 | if (!dst_pmd) |
| 963 | return -ENOMEM; |
| 964 | src_pmd = pmd_offset(src_pud, addr); |
| 965 | do { |
| 966 | next = pmd_addr_end(addr, end); |
| 967 | if (pmd_trans_huge(*src_pmd)) { |
| 968 | int err; |
| 969 | VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); |
| 970 | err = copy_huge_pmd(dst_mm, src_mm, |
| 971 | dst_pmd, src_pmd, addr, vma); |
| 972 | if (err == -ENOMEM) |
| 973 | return -ENOMEM; |
| 974 | if (!err) |
| 975 | continue; |
| 976 | /* fall through */ |
| 977 | } |
| 978 | if (pmd_none_or_clear_bad(src_pmd)) |
| 979 | continue; |
| 980 | if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, |
| 981 | vma, addr, next)) |
| 982 | return -ENOMEM; |
| 983 | } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
| 984 | return 0; |
| 985 | } |
| 986 | |
| 987 | static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| 988 | pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, |
| 989 | unsigned long addr, unsigned long end) |
| 990 | { |
| 991 | pud_t *src_pud, *dst_pud; |
| 992 | unsigned long next; |
| 993 | |
| 994 | dst_pud = pud_alloc(dst_mm, dst_pgd, addr); |
| 995 | if (!dst_pud) |
| 996 | return -ENOMEM; |
| 997 | src_pud = pud_offset(src_pgd, addr); |
| 998 | do { |
| 999 | next = pud_addr_end(addr, end); |
| 1000 | if (pud_none_or_clear_bad(src_pud)) |
| 1001 | continue; |
| 1002 | if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, |
| 1003 | vma, addr, next)) |
| 1004 | return -ENOMEM; |
| 1005 | } while (dst_pud++, src_pud++, addr = next, addr != end); |
| 1006 | return 0; |
| 1007 | } |
| 1008 | |
| 1009 | int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| 1010 | struct vm_area_struct *vma) |
| 1011 | { |
| 1012 | pgd_t *src_pgd, *dst_pgd; |
| 1013 | unsigned long next; |
| 1014 | unsigned long addr = vma->vm_start; |
| 1015 | unsigned long end = vma->vm_end; |
| 1016 | unsigned long mmun_start; /* For mmu_notifiers */ |
| 1017 | unsigned long mmun_end; /* For mmu_notifiers */ |
| 1018 | bool is_cow; |
| 1019 | int ret; |
| 1020 | |
| 1021 | /* |
| 1022 | * Don't copy ptes where a page fault will fill them correctly. |
| 1023 | * Fork becomes much lighter when there are big shared or private |
| 1024 | * readonly mappings. The tradeoff is that copy_page_range is more |
| 1025 | * efficient than faulting. |
| 1026 | */ |
| 1027 | if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | |
| 1028 | VM_PFNMAP | VM_MIXEDMAP))) { |
| 1029 | if (!vma->anon_vma) |
| 1030 | return 0; |
| 1031 | } |
| 1032 | |
| 1033 | if (is_vm_hugetlb_page(vma)) |
| 1034 | return copy_hugetlb_page_range(dst_mm, src_mm, vma); |
| 1035 | |
| 1036 | if (unlikely(vma->vm_flags & VM_PFNMAP)) { |
| 1037 | /* |
| 1038 | * We do not free on error cases below as remove_vma |
| 1039 | * gets called on error from higher level routine |
| 1040 | */ |
| 1041 | ret = track_pfn_copy(vma); |
| 1042 | if (ret) |
| 1043 | return ret; |
| 1044 | } |
| 1045 | |
| 1046 | /* |
| 1047 | * We need to invalidate the secondary MMU mappings only when |
| 1048 | * there could be a permission downgrade on the ptes of the |
| 1049 | * parent mm. And a permission downgrade will only happen if |
| 1050 | * is_cow_mapping() returns true. |
| 1051 | */ |
| 1052 | is_cow = is_cow_mapping(vma->vm_flags); |
| 1053 | mmun_start = addr; |
| 1054 | mmun_end = end; |
| 1055 | if (is_cow) |
| 1056 | mmu_notifier_invalidate_range_start(src_mm, mmun_start, |
| 1057 | mmun_end); |
| 1058 | |
| 1059 | ret = 0; |
| 1060 | dst_pgd = pgd_offset(dst_mm, addr); |
| 1061 | src_pgd = pgd_offset(src_mm, addr); |
| 1062 | do { |
| 1063 | next = pgd_addr_end(addr, end); |
| 1064 | if (pgd_none_or_clear_bad(src_pgd)) |
| 1065 | continue; |
| 1066 | if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, |
| 1067 | vma, addr, next))) { |
| 1068 | ret = -ENOMEM; |
| 1069 | break; |
| 1070 | } |
| 1071 | } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
| 1072 | |
| 1073 | if (is_cow) |
| 1074 | mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); |
| 1075 | return ret; |
| 1076 | } |
| 1077 | |
| 1078 | static unsigned long zap_pte_range(struct mmu_gather *tlb, |
| 1079 | struct vm_area_struct *vma, pmd_t *pmd, |
| 1080 | unsigned long addr, unsigned long end, |
| 1081 | struct zap_details *details) |
| 1082 | { |
| 1083 | struct mm_struct *mm = tlb->mm; |
| 1084 | int force_flush = 0; |
| 1085 | int rss[NR_MM_COUNTERS]; |
| 1086 | spinlock_t *ptl; |
| 1087 | pte_t *start_pte; |
| 1088 | pte_t *pte; |
| 1089 | |
| 1090 | again: |
| 1091 | init_rss_vec(rss); |
| 1092 | start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| 1093 | pte = start_pte; |
| 1094 | arch_enter_lazy_mmu_mode(); |
| 1095 | do { |
| 1096 | pte_t ptent = *pte; |
| 1097 | if (pte_none(ptent)) { |
| 1098 | continue; |
| 1099 | } |
| 1100 | |
| 1101 | if (pte_present(ptent)) { |
| 1102 | struct page *page; |
| 1103 | |
| 1104 | page = vm_normal_page(vma, addr, ptent); |
| 1105 | if (unlikely(details) && page) { |
| 1106 | /* |
| 1107 | * unmap_shared_mapping_pages() wants to |
| 1108 | * invalidate cache without truncating: |
| 1109 | * unmap shared but keep private pages. |
| 1110 | */ |
| 1111 | if (details->check_mapping && |
| 1112 | details->check_mapping != page->mapping) |
| 1113 | continue; |
| 1114 | /* |
| 1115 | * Each page->index must be checked when |
| 1116 | * invalidating or truncating nonlinear. |
| 1117 | */ |
| 1118 | if (details->nonlinear_vma && |
| 1119 | (page->index < details->first_index || |
| 1120 | page->index > details->last_index)) |
| 1121 | continue; |
| 1122 | } |
| 1123 | ptent = ptep_get_and_clear_full(mm, addr, pte, |
| 1124 | tlb->fullmm); |
| 1125 | tlb_remove_tlb_entry(tlb, pte, addr); |
| 1126 | if (unlikely(!page)) |
| 1127 | continue; |
| 1128 | if (unlikely(details) && details->nonlinear_vma |
| 1129 | && linear_page_index(details->nonlinear_vma, |
| 1130 | addr) != page->index) { |
| 1131 | pte_t ptfile = pgoff_to_pte(page->index); |
| 1132 | if (pte_soft_dirty(ptent)) |
| 1133 | pte_file_mksoft_dirty(ptfile); |
| 1134 | set_pte_at(mm, addr, pte, ptfile); |
| 1135 | } |
| 1136 | if (PageAnon(page)) |
| 1137 | rss[MM_ANONPAGES]--; |
| 1138 | else { |
| 1139 | if (pte_dirty(ptent)) { |
| 1140 | force_flush = 1; |
| 1141 | set_page_dirty(page); |
| 1142 | } |
| 1143 | if (pte_young(ptent) && |
| 1144 | likely(!(vma->vm_flags & VM_SEQ_READ))) |
| 1145 | mark_page_accessed(page); |
| 1146 | rss[MM_FILEPAGES]--; |
| 1147 | } |
| 1148 | page_remove_rmap(page); |
| 1149 | if (unlikely(page_mapcount(page) < 0)) |
| 1150 | print_bad_pte(vma, addr, ptent, page); |
| 1151 | if (unlikely(!__tlb_remove_page(tlb, page))) { |
| 1152 | force_flush = 1; |
| 1153 | break; |
| 1154 | } |
| 1155 | continue; |
| 1156 | } |
| 1157 | /* |
| 1158 | * If details->check_mapping, we leave swap entries; |
| 1159 | * if details->nonlinear_vma, we leave file entries. |
| 1160 | */ |
| 1161 | if (unlikely(details)) |
| 1162 | continue; |
| 1163 | if (pte_file(ptent)) { |
| 1164 | if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) |
| 1165 | print_bad_pte(vma, addr, ptent, NULL); |
| 1166 | } else { |
| 1167 | swp_entry_t entry = pte_to_swp_entry(ptent); |
| 1168 | |
| 1169 | if (!non_swap_entry(entry)) |
| 1170 | rss[MM_SWAPENTS]--; |
| 1171 | else if (is_migration_entry(entry)) { |
| 1172 | struct page *page; |
| 1173 | |
| 1174 | page = migration_entry_to_page(entry); |
| 1175 | |
| 1176 | if (PageAnon(page)) |
| 1177 | rss[MM_ANONPAGES]--; |
| 1178 | else |
| 1179 | rss[MM_FILEPAGES]--; |
| 1180 | } |
| 1181 | if (unlikely(!free_swap_and_cache(entry))) |
| 1182 | print_bad_pte(vma, addr, ptent, NULL); |
| 1183 | } |
| 1184 | pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); |
| 1185 | } while (pte++, addr += PAGE_SIZE, addr != end); |
| 1186 | |
| 1187 | add_mm_rss_vec(mm, rss); |
| 1188 | arch_leave_lazy_mmu_mode(); |
| 1189 | |
| 1190 | /* Do the actual TLB flush before dropping ptl */ |
| 1191 | if (force_flush) { |
| 1192 | unsigned long old_end; |
| 1193 | |
| 1194 | /* |
| 1195 | * Flush the TLB just for the previous segment, |
| 1196 | * then update the range to be the remaining |
| 1197 | * TLB range. |
| 1198 | */ |
| 1199 | old_end = tlb->end; |
| 1200 | tlb->end = addr; |
| 1201 | tlb_flush_mmu_tlbonly(tlb); |
| 1202 | tlb->start = addr; |
| 1203 | tlb->end = old_end; |
| 1204 | } |
| 1205 | pte_unmap_unlock(start_pte, ptl); |
| 1206 | |
| 1207 | /* |
| 1208 | * If we forced a TLB flush (either due to running out of |
| 1209 | * batch buffers or because we needed to flush dirty TLB |
| 1210 | * entries before releasing the ptl), free the batched |
| 1211 | * memory too. Restart if we didn't do everything. |
| 1212 | */ |
| 1213 | if (force_flush) { |
| 1214 | force_flush = 0; |
| 1215 | tlb_flush_mmu_free(tlb); |
| 1216 | |
| 1217 | if (addr != end) |
| 1218 | goto again; |
| 1219 | } |
| 1220 | |
| 1221 | return addr; |
| 1222 | } |
| 1223 | |
| 1224 | static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
| 1225 | struct vm_area_struct *vma, pud_t *pud, |
| 1226 | unsigned long addr, unsigned long end, |
| 1227 | struct zap_details *details) |
| 1228 | { |
| 1229 | pmd_t *pmd; |
| 1230 | unsigned long next; |
| 1231 | |
| 1232 | pmd = pmd_offset(pud, addr); |
| 1233 | do { |
| 1234 | next = pmd_addr_end(addr, end); |
| 1235 | if (pmd_trans_huge(*pmd)) { |
| 1236 | if (next - addr != HPAGE_PMD_SIZE) { |
| 1237 | #ifdef CONFIG_DEBUG_VM |
| 1238 | if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { |
| 1239 | pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", |
| 1240 | __func__, addr, end, |
| 1241 | vma->vm_start, |
| 1242 | vma->vm_end); |
| 1243 | BUG(); |
| 1244 | } |
| 1245 | #endif |
| 1246 | split_huge_page_pmd(vma, addr, pmd); |
| 1247 | } else if (zap_huge_pmd(tlb, vma, pmd, addr)) |
| 1248 | goto next; |
| 1249 | /* fall through */ |
| 1250 | } |
| 1251 | /* |
| 1252 | * Here there can be other concurrent MADV_DONTNEED or |
| 1253 | * trans huge page faults running, and if the pmd is |
| 1254 | * none or trans huge it can change under us. This is |
| 1255 | * because MADV_DONTNEED holds the mmap_sem in read |
| 1256 | * mode. |
| 1257 | */ |
| 1258 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
| 1259 | goto next; |
| 1260 | next = zap_pte_range(tlb, vma, pmd, addr, next, details); |
| 1261 | next: |
| 1262 | cond_resched(); |
| 1263 | } while (pmd++, addr = next, addr != end); |
| 1264 | |
| 1265 | return addr; |
| 1266 | } |
| 1267 | |
| 1268 | static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
| 1269 | struct vm_area_struct *vma, pgd_t *pgd, |
| 1270 | unsigned long addr, unsigned long end, |
| 1271 | struct zap_details *details) |
| 1272 | { |
| 1273 | pud_t *pud; |
| 1274 | unsigned long next; |
| 1275 | |
| 1276 | pud = pud_offset(pgd, addr); |
| 1277 | do { |
| 1278 | next = pud_addr_end(addr, end); |
| 1279 | if (pud_none_or_clear_bad(pud)) |
| 1280 | continue; |
| 1281 | next = zap_pmd_range(tlb, vma, pud, addr, next, details); |
| 1282 | } while (pud++, addr = next, addr != end); |
| 1283 | |
| 1284 | return addr; |
| 1285 | } |
| 1286 | |
| 1287 | static void unmap_page_range(struct mmu_gather *tlb, |
| 1288 | struct vm_area_struct *vma, |
| 1289 | unsigned long addr, unsigned long end, |
| 1290 | struct zap_details *details) |
| 1291 | { |
| 1292 | pgd_t *pgd; |
| 1293 | unsigned long next; |
| 1294 | |
| 1295 | if (details && !details->check_mapping && !details->nonlinear_vma) |
| 1296 | details = NULL; |
| 1297 | |
| 1298 | BUG_ON(addr >= end); |
| 1299 | mem_cgroup_uncharge_start(); |
| 1300 | tlb_start_vma(tlb, vma); |
| 1301 | pgd = pgd_offset(vma->vm_mm, addr); |
| 1302 | do { |
| 1303 | next = pgd_addr_end(addr, end); |
| 1304 | if (pgd_none_or_clear_bad(pgd)) |
| 1305 | continue; |
| 1306 | next = zap_pud_range(tlb, vma, pgd, addr, next, details); |
| 1307 | } while (pgd++, addr = next, addr != end); |
| 1308 | tlb_end_vma(tlb, vma); |
| 1309 | mem_cgroup_uncharge_end(); |
| 1310 | } |
| 1311 | |
| 1312 | |
| 1313 | static void unmap_single_vma(struct mmu_gather *tlb, |
| 1314 | struct vm_area_struct *vma, unsigned long start_addr, |
| 1315 | unsigned long end_addr, |
| 1316 | struct zap_details *details) |
| 1317 | { |
| 1318 | unsigned long start = max(vma->vm_start, start_addr); |
| 1319 | unsigned long end; |
| 1320 | |
| 1321 | if (start >= vma->vm_end) |
| 1322 | return; |
| 1323 | end = min(vma->vm_end, end_addr); |
| 1324 | if (end <= vma->vm_start) |
| 1325 | return; |
| 1326 | |
| 1327 | if (vma->vm_file) |
| 1328 | uprobe_munmap(vma, start, end); |
| 1329 | |
| 1330 | if (unlikely(vma->vm_flags & VM_PFNMAP)) |
| 1331 | untrack_pfn(vma, 0, 0); |
| 1332 | |
| 1333 | if (start != end) { |
| 1334 | if (unlikely(is_vm_hugetlb_page(vma))) { |
| 1335 | /* |
| 1336 | * It is undesirable to test vma->vm_file as it |
| 1337 | * should be non-null for valid hugetlb area. |
| 1338 | * However, vm_file will be NULL in the error |
| 1339 | * cleanup path of mmap_region. When |
| 1340 | * hugetlbfs ->mmap method fails, |
| 1341 | * mmap_region() nullifies vma->vm_file |
| 1342 | * before calling this function to clean up. |
| 1343 | * Since no pte has actually been setup, it is |
| 1344 | * safe to do nothing in this case. |
| 1345 | */ |
| 1346 | if (vma->vm_file) { |
| 1347 | mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); |
| 1348 | __unmap_hugepage_range_final(tlb, vma, start, end, NULL); |
| 1349 | mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); |
| 1350 | } |
| 1351 | } else |
| 1352 | unmap_page_range(tlb, vma, start, end, details); |
| 1353 | } |
| 1354 | } |
| 1355 | |
| 1356 | /** |
| 1357 | * unmap_vmas - unmap a range of memory covered by a list of vma's |
| 1358 | * @tlb: address of the caller's struct mmu_gather |
| 1359 | * @vma: the starting vma |
| 1360 | * @start_addr: virtual address at which to start unmapping |
| 1361 | * @end_addr: virtual address at which to end unmapping |
| 1362 | * |
| 1363 | * Unmap all pages in the vma list. |
| 1364 | * |
| 1365 | * Only addresses between `start' and `end' will be unmapped. |
| 1366 | * |
| 1367 | * The VMA list must be sorted in ascending virtual address order. |
| 1368 | * |
| 1369 | * unmap_vmas() assumes that the caller will flush the whole unmapped address |
| 1370 | * range after unmap_vmas() returns. So the only responsibility here is to |
| 1371 | * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
| 1372 | * drops the lock and schedules. |
| 1373 | */ |
| 1374 | void unmap_vmas(struct mmu_gather *tlb, |
| 1375 | struct vm_area_struct *vma, unsigned long start_addr, |
| 1376 | unsigned long end_addr) |
| 1377 | { |
| 1378 | struct mm_struct *mm = vma->vm_mm; |
| 1379 | |
| 1380 | mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); |
| 1381 | for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) |
| 1382 | unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); |
| 1383 | mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); |
| 1384 | } |
| 1385 | |
| 1386 | /** |
| 1387 | * zap_page_range - remove user pages in a given range |
| 1388 | * @vma: vm_area_struct holding the applicable pages |
| 1389 | * @start: starting address of pages to zap |
| 1390 | * @size: number of bytes to zap |
| 1391 | * @details: details of nonlinear truncation or shared cache invalidation |
| 1392 | * |
| 1393 | * Caller must protect the VMA list |
| 1394 | */ |
| 1395 | void zap_page_range(struct vm_area_struct *vma, unsigned long start, |
| 1396 | unsigned long size, struct zap_details *details) |
| 1397 | { |
| 1398 | struct mm_struct *mm = vma->vm_mm; |
| 1399 | struct mmu_gather tlb; |
| 1400 | unsigned long end = start + size; |
| 1401 | |
| 1402 | lru_add_drain(); |
| 1403 | tlb_gather_mmu(&tlb, mm, start, end); |
| 1404 | update_hiwater_rss(mm); |
| 1405 | mmu_notifier_invalidate_range_start(mm, start, end); |
| 1406 | for ( ; vma && vma->vm_start < end; vma = vma->vm_next) |
| 1407 | unmap_single_vma(&tlb, vma, start, end, details); |
| 1408 | mmu_notifier_invalidate_range_end(mm, start, end); |
| 1409 | tlb_finish_mmu(&tlb, start, end); |
| 1410 | } |
| 1411 | |
| 1412 | /** |
| 1413 | * zap_page_range_single - remove user pages in a given range |
| 1414 | * @vma: vm_area_struct holding the applicable pages |
| 1415 | * @address: starting address of pages to zap |
| 1416 | * @size: number of bytes to zap |
| 1417 | * @details: details of nonlinear truncation or shared cache invalidation |
| 1418 | * |
| 1419 | * The range must fit into one VMA. |
| 1420 | */ |
| 1421 | static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, |
| 1422 | unsigned long size, struct zap_details *details) |
| 1423 | { |
| 1424 | struct mm_struct *mm = vma->vm_mm; |
| 1425 | struct mmu_gather tlb; |
| 1426 | unsigned long end = address + size; |
| 1427 | |
| 1428 | lru_add_drain(); |
| 1429 | tlb_gather_mmu(&tlb, mm, address, end); |
| 1430 | update_hiwater_rss(mm); |
| 1431 | mmu_notifier_invalidate_range_start(mm, address, end); |
| 1432 | unmap_single_vma(&tlb, vma, address, end, details); |
| 1433 | mmu_notifier_invalidate_range_end(mm, address, end); |
| 1434 | tlb_finish_mmu(&tlb, address, end); |
| 1435 | } |
| 1436 | |
| 1437 | /** |
| 1438 | * zap_vma_ptes - remove ptes mapping the vma |
| 1439 | * @vma: vm_area_struct holding ptes to be zapped |
| 1440 | * @address: starting address of pages to zap |
| 1441 | * @size: number of bytes to zap |
| 1442 | * |
| 1443 | * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
| 1444 | * |
| 1445 | * The entire address range must be fully contained within the vma. |
| 1446 | * |
| 1447 | * Returns 0 if successful. |
| 1448 | */ |
| 1449 | int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
| 1450 | unsigned long size) |
| 1451 | { |
| 1452 | if (address < vma->vm_start || address + size > vma->vm_end || |
| 1453 | !(vma->vm_flags & VM_PFNMAP)) |
| 1454 | return -1; |
| 1455 | zap_page_range_single(vma, address, size, NULL); |
| 1456 | return 0; |
| 1457 | } |
| 1458 | EXPORT_SYMBOL_GPL(zap_vma_ptes); |
| 1459 | |
| 1460 | /** |
| 1461 | * follow_page_mask - look up a page descriptor from a user-virtual address |
| 1462 | * @vma: vm_area_struct mapping @address |
| 1463 | * @address: virtual address to look up |
| 1464 | * @flags: flags modifying lookup behaviour |
| 1465 | * @page_mask: on output, *page_mask is set according to the size of the page |
| 1466 | * |
| 1467 | * @flags can have FOLL_ flags set, defined in <linux/mm.h> |
| 1468 | * |
| 1469 | * Returns the mapped (struct page *), %NULL if no mapping exists, or |
| 1470 | * an error pointer if there is a mapping to something not represented |
| 1471 | * by a page descriptor (see also vm_normal_page()). |
| 1472 | */ |
| 1473 | struct page *follow_page_mask(struct vm_area_struct *vma, |
| 1474 | unsigned long address, unsigned int flags, |
| 1475 | unsigned int *page_mask) |
| 1476 | { |
| 1477 | pgd_t *pgd; |
| 1478 | pud_t *pud; |
| 1479 | pmd_t *pmd; |
| 1480 | pte_t *ptep, pte; |
| 1481 | spinlock_t *ptl; |
| 1482 | struct page *page; |
| 1483 | struct mm_struct *mm = vma->vm_mm; |
| 1484 | |
| 1485 | *page_mask = 0; |
| 1486 | |
| 1487 | page = follow_huge_addr(mm, address, flags & FOLL_WRITE); |
| 1488 | if (!IS_ERR(page)) { |
| 1489 | BUG_ON(flags & FOLL_GET); |
| 1490 | goto out; |
| 1491 | } |
| 1492 | |
| 1493 | page = NULL; |
| 1494 | pgd = pgd_offset(mm, address); |
| 1495 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| 1496 | goto no_page_table; |
| 1497 | |
| 1498 | pud = pud_offset(pgd, address); |
| 1499 | if (pud_none(*pud)) |
| 1500 | goto no_page_table; |
| 1501 | if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { |
| 1502 | if (flags & FOLL_GET) |
| 1503 | goto out; |
| 1504 | page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); |
| 1505 | goto out; |
| 1506 | } |
| 1507 | if (unlikely(pud_bad(*pud))) |
| 1508 | goto no_page_table; |
| 1509 | |
| 1510 | pmd = pmd_offset(pud, address); |
| 1511 | if (pmd_none(*pmd)) |
| 1512 | goto no_page_table; |
| 1513 | if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { |
| 1514 | page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); |
| 1515 | if (flags & FOLL_GET) { |
| 1516 | /* |
| 1517 | * Refcount on tail pages are not well-defined and |
| 1518 | * shouldn't be taken. The caller should handle a NULL |
| 1519 | * return when trying to follow tail pages. |
| 1520 | */ |
| 1521 | if (PageHead(page)) |
| 1522 | get_page(page); |
| 1523 | else { |
| 1524 | page = NULL; |
| 1525 | goto out; |
| 1526 | } |
| 1527 | } |
| 1528 | goto out; |
| 1529 | } |
| 1530 | if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) |
| 1531 | goto no_page_table; |
| 1532 | if (pmd_trans_huge(*pmd)) { |
| 1533 | if (flags & FOLL_SPLIT) { |
| 1534 | split_huge_page_pmd(vma, address, pmd); |
| 1535 | goto split_fallthrough; |
| 1536 | } |
| 1537 | ptl = pmd_lock(mm, pmd); |
| 1538 | if (likely(pmd_trans_huge(*pmd))) { |
| 1539 | if (unlikely(pmd_trans_splitting(*pmd))) { |
| 1540 | spin_unlock(ptl); |
| 1541 | wait_split_huge_page(vma->anon_vma, pmd); |
| 1542 | } else { |
| 1543 | page = follow_trans_huge_pmd(vma, address, |
| 1544 | pmd, flags); |
| 1545 | spin_unlock(ptl); |
| 1546 | *page_mask = HPAGE_PMD_NR - 1; |
| 1547 | goto out; |
| 1548 | } |
| 1549 | } else |
| 1550 | spin_unlock(ptl); |
| 1551 | /* fall through */ |
| 1552 | } |
| 1553 | split_fallthrough: |
| 1554 | if (unlikely(pmd_bad(*pmd))) |
| 1555 | goto no_page_table; |
| 1556 | |
| 1557 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 1558 | |
| 1559 | pte = *ptep; |
| 1560 | if (!pte_present(pte)) { |
| 1561 | swp_entry_t entry; |
| 1562 | /* |
| 1563 | * KSM's break_ksm() relies upon recognizing a ksm page |
| 1564 | * even while it is being migrated, so for that case we |
| 1565 | * need migration_entry_wait(). |
| 1566 | */ |
| 1567 | if (likely(!(flags & FOLL_MIGRATION))) |
| 1568 | goto no_page; |
| 1569 | if (pte_none(pte) || pte_file(pte)) |
| 1570 | goto no_page; |
| 1571 | entry = pte_to_swp_entry(pte); |
| 1572 | if (!is_migration_entry(entry)) |
| 1573 | goto no_page; |
| 1574 | pte_unmap_unlock(ptep, ptl); |
| 1575 | migration_entry_wait(mm, pmd, address); |
| 1576 | goto split_fallthrough; |
| 1577 | } |
| 1578 | if ((flags & FOLL_NUMA) && pte_numa(pte)) |
| 1579 | goto no_page; |
| 1580 | if ((flags & FOLL_WRITE) && !pte_write(pte)) |
| 1581 | goto unlock; |
| 1582 | |
| 1583 | page = vm_normal_page(vma, address, pte); |
| 1584 | if (unlikely(!page)) { |
| 1585 | if ((flags & FOLL_DUMP) || |
| 1586 | !is_zero_pfn(pte_pfn(pte))) |
| 1587 | goto bad_page; |
| 1588 | page = pte_page(pte); |
| 1589 | } |
| 1590 | |
| 1591 | if (flags & FOLL_GET) |
| 1592 | get_page_foll(page); |
| 1593 | if (flags & FOLL_TOUCH) { |
| 1594 | if ((flags & FOLL_WRITE) && |
| 1595 | !pte_dirty(pte) && !PageDirty(page)) |
| 1596 | set_page_dirty(page); |
| 1597 | /* |
| 1598 | * pte_mkyoung() would be more correct here, but atomic care |
| 1599 | * is needed to avoid losing the dirty bit: it is easier to use |
| 1600 | * mark_page_accessed(). |
| 1601 | */ |
| 1602 | mark_page_accessed(page); |
| 1603 | } |
| 1604 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
| 1605 | /* |
| 1606 | * The preliminary mapping check is mainly to avoid the |
| 1607 | * pointless overhead of lock_page on the ZERO_PAGE |
| 1608 | * which might bounce very badly if there is contention. |
| 1609 | * |
| 1610 | * If the page is already locked, we don't need to |
| 1611 | * handle it now - vmscan will handle it later if and |
| 1612 | * when it attempts to reclaim the page. |
| 1613 | */ |
| 1614 | if (page->mapping && trylock_page(page)) { |
| 1615 | lru_add_drain(); /* push cached pages to LRU */ |
| 1616 | /* |
| 1617 | * Because we lock page here, and migration is |
| 1618 | * blocked by the pte's page reference, and we |
| 1619 | * know the page is still mapped, we don't even |
| 1620 | * need to check for file-cache page truncation. |
| 1621 | */ |
| 1622 | mlock_vma_page(page); |
| 1623 | unlock_page(page); |
| 1624 | } |
| 1625 | } |
| 1626 | unlock: |
| 1627 | pte_unmap_unlock(ptep, ptl); |
| 1628 | out: |
| 1629 | return page; |
| 1630 | |
| 1631 | bad_page: |
| 1632 | pte_unmap_unlock(ptep, ptl); |
| 1633 | return ERR_PTR(-EFAULT); |
| 1634 | |
| 1635 | no_page: |
| 1636 | pte_unmap_unlock(ptep, ptl); |
| 1637 | if (!pte_none(pte)) |
| 1638 | return page; |
| 1639 | |
| 1640 | no_page_table: |
| 1641 | /* |
| 1642 | * When core dumping an enormous anonymous area that nobody |
| 1643 | * has touched so far, we don't want to allocate unnecessary pages or |
| 1644 | * page tables. Return error instead of NULL to skip handle_mm_fault, |
| 1645 | * then get_dump_page() will return NULL to leave a hole in the dump. |
| 1646 | * But we can only make this optimization where a hole would surely |
| 1647 | * be zero-filled if handle_mm_fault() actually did handle it. |
| 1648 | */ |
| 1649 | if ((flags & FOLL_DUMP) && |
| 1650 | (!vma->vm_ops || !vma->vm_ops->fault)) |
| 1651 | return ERR_PTR(-EFAULT); |
| 1652 | return page; |
| 1653 | } |
| 1654 | |
| 1655 | static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) |
| 1656 | { |
| 1657 | return stack_guard_page_start(vma, addr) || |
| 1658 | stack_guard_page_end(vma, addr+PAGE_SIZE); |
| 1659 | } |
| 1660 | |
| 1661 | /** |
| 1662 | * __get_user_pages() - pin user pages in memory |
| 1663 | * @tsk: task_struct of target task |
| 1664 | * @mm: mm_struct of target mm |
| 1665 | * @start: starting user address |
| 1666 | * @nr_pages: number of pages from start to pin |
| 1667 | * @gup_flags: flags modifying pin behaviour |
| 1668 | * @pages: array that receives pointers to the pages pinned. |
| 1669 | * Should be at least nr_pages long. Or NULL, if caller |
| 1670 | * only intends to ensure the pages are faulted in. |
| 1671 | * @vmas: array of pointers to vmas corresponding to each page. |
| 1672 | * Or NULL if the caller does not require them. |
| 1673 | * @nonblocking: whether waiting for disk IO or mmap_sem contention |
| 1674 | * |
| 1675 | * Returns number of pages pinned. This may be fewer than the number |
| 1676 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
| 1677 | * were pinned, returns -errno. Each page returned must be released |
| 1678 | * with a put_page() call when it is finished with. vmas will only |
| 1679 | * remain valid while mmap_sem is held. |
| 1680 | * |
| 1681 | * Must be called with mmap_sem held for read or write. |
| 1682 | * |
| 1683 | * __get_user_pages walks a process's page tables and takes a reference to |
| 1684 | * each struct page that each user address corresponds to at a given |
| 1685 | * instant. That is, it takes the page that would be accessed if a user |
| 1686 | * thread accesses the given user virtual address at that instant. |
| 1687 | * |
| 1688 | * This does not guarantee that the page exists in the user mappings when |
| 1689 | * __get_user_pages returns, and there may even be a completely different |
| 1690 | * page there in some cases (eg. if mmapped pagecache has been invalidated |
| 1691 | * and subsequently re faulted). However it does guarantee that the page |
| 1692 | * won't be freed completely. And mostly callers simply care that the page |
| 1693 | * contains data that was valid *at some point in time*. Typically, an IO |
| 1694 | * or similar operation cannot guarantee anything stronger anyway because |
| 1695 | * locks can't be held over the syscall boundary. |
| 1696 | * |
| 1697 | * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If |
| 1698 | * the page is written to, set_page_dirty (or set_page_dirty_lock, as |
| 1699 | * appropriate) must be called after the page is finished with, and |
| 1700 | * before put_page is called. |
| 1701 | * |
| 1702 | * If @nonblocking != NULL, __get_user_pages will not wait for disk IO |
| 1703 | * or mmap_sem contention, and if waiting is needed to pin all pages, |
| 1704 | * *@nonblocking will be set to 0. |
| 1705 | * |
| 1706 | * In most cases, get_user_pages or get_user_pages_fast should be used |
| 1707 | * instead of __get_user_pages. __get_user_pages should be used only if |
| 1708 | * you need some special @gup_flags. |
| 1709 | */ |
| 1710 | long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
| 1711 | unsigned long start, unsigned long nr_pages, |
| 1712 | unsigned int gup_flags, struct page **pages, |
| 1713 | struct vm_area_struct **vmas, int *nonblocking) |
| 1714 | { |
| 1715 | long i; |
| 1716 | unsigned long vm_flags; |
| 1717 | unsigned int page_mask; |
| 1718 | |
| 1719 | if (!nr_pages) |
| 1720 | return 0; |
| 1721 | |
| 1722 | VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); |
| 1723 | |
| 1724 | /* |
| 1725 | * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault |
| 1726 | * would be called on PROT_NONE ranges. We must never invoke |
| 1727 | * handle_mm_fault on PROT_NONE ranges or the NUMA hinting |
| 1728 | * page faults would unprotect the PROT_NONE ranges if |
| 1729 | * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd |
| 1730 | * bitflag. So to avoid that, don't set FOLL_NUMA if |
| 1731 | * FOLL_FORCE is set. |
| 1732 | */ |
| 1733 | if (!(gup_flags & FOLL_FORCE)) |
| 1734 | gup_flags |= FOLL_NUMA; |
| 1735 | |
| 1736 | i = 0; |
| 1737 | |
| 1738 | do { |
| 1739 | struct vm_area_struct *vma; |
| 1740 | |
| 1741 | vma = find_extend_vma(mm, start); |
| 1742 | if (!vma && in_gate_area(mm, start)) { |
| 1743 | unsigned long pg = start & PAGE_MASK; |
| 1744 | pgd_t *pgd; |
| 1745 | pud_t *pud; |
| 1746 | pmd_t *pmd; |
| 1747 | pte_t *pte; |
| 1748 | |
| 1749 | /* user gate pages are read-only */ |
| 1750 | if (gup_flags & FOLL_WRITE) |
| 1751 | goto efault; |
| 1752 | if (pg > TASK_SIZE) |
| 1753 | pgd = pgd_offset_k(pg); |
| 1754 | else |
| 1755 | pgd = pgd_offset_gate(mm, pg); |
| 1756 | BUG_ON(pgd_none(*pgd)); |
| 1757 | pud = pud_offset(pgd, pg); |
| 1758 | BUG_ON(pud_none(*pud)); |
| 1759 | pmd = pmd_offset(pud, pg); |
| 1760 | if (pmd_none(*pmd)) |
| 1761 | goto efault; |
| 1762 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
| 1763 | pte = pte_offset_map(pmd, pg); |
| 1764 | if (pte_none(*pte)) { |
| 1765 | pte_unmap(pte); |
| 1766 | goto efault; |
| 1767 | } |
| 1768 | vma = get_gate_vma(mm); |
| 1769 | if (pages) { |
| 1770 | struct page *page; |
| 1771 | |
| 1772 | page = vm_normal_page(vma, start, *pte); |
| 1773 | if (!page) { |
| 1774 | if (!(gup_flags & FOLL_DUMP) && |
| 1775 | is_zero_pfn(pte_pfn(*pte))) |
| 1776 | page = pte_page(*pte); |
| 1777 | else { |
| 1778 | pte_unmap(pte); |
| 1779 | goto efault; |
| 1780 | } |
| 1781 | } |
| 1782 | pages[i] = page; |
| 1783 | get_page(page); |
| 1784 | } |
| 1785 | pte_unmap(pte); |
| 1786 | page_mask = 0; |
| 1787 | goto next_page; |
| 1788 | } |
| 1789 | |
| 1790 | if (!vma) |
| 1791 | goto efault; |
| 1792 | vm_flags = vma->vm_flags; |
| 1793 | if (vm_flags & (VM_IO | VM_PFNMAP)) |
| 1794 | goto efault; |
| 1795 | |
| 1796 | if (gup_flags & FOLL_WRITE) { |
| 1797 | if (!(vm_flags & VM_WRITE)) { |
| 1798 | if (!(gup_flags & FOLL_FORCE)) |
| 1799 | goto efault; |
| 1800 | /* |
| 1801 | * We used to let the write,force case do COW |
| 1802 | * in a VM_MAYWRITE VM_SHARED !VM_WRITE vma, so |
| 1803 | * ptrace could set a breakpoint in a read-only |
| 1804 | * mapping of an executable, without corrupting |
| 1805 | * the file (yet only when that file had been |
| 1806 | * opened for writing!). Anon pages in shared |
| 1807 | * mappings are surprising: now just reject it. |
| 1808 | */ |
| 1809 | if (!is_cow_mapping(vm_flags)) { |
| 1810 | WARN_ON_ONCE(vm_flags & VM_MAYWRITE); |
| 1811 | goto efault; |
| 1812 | } |
| 1813 | } |
| 1814 | } else { |
| 1815 | if (!(vm_flags & VM_READ)) { |
| 1816 | if (!(gup_flags & FOLL_FORCE)) |
| 1817 | goto efault; |
| 1818 | /* |
| 1819 | * Is there actually any vma we can reach here |
| 1820 | * which does not have VM_MAYREAD set? |
| 1821 | */ |
| 1822 | if (!(vm_flags & VM_MAYREAD)) |
| 1823 | goto efault; |
| 1824 | } |
| 1825 | } |
| 1826 | |
| 1827 | if (is_vm_hugetlb_page(vma)) { |
| 1828 | i = follow_hugetlb_page(mm, vma, pages, vmas, |
| 1829 | &start, &nr_pages, i, gup_flags); |
| 1830 | continue; |
| 1831 | } |
| 1832 | |
| 1833 | do { |
| 1834 | struct page *page; |
| 1835 | unsigned int foll_flags = gup_flags; |
| 1836 | unsigned int page_increm; |
| 1837 | |
| 1838 | /* |
| 1839 | * If we have a pending SIGKILL, don't keep faulting |
| 1840 | * pages and potentially allocating memory. |
| 1841 | */ |
| 1842 | if (unlikely(fatal_signal_pending(current))) |
| 1843 | return i ? i : -ERESTARTSYS; |
| 1844 | |
| 1845 | cond_resched(); |
| 1846 | while (!(page = follow_page_mask(vma, start, |
| 1847 | foll_flags, &page_mask))) { |
| 1848 | int ret; |
| 1849 | unsigned int fault_flags = 0; |
| 1850 | |
| 1851 | /* For mlock, just skip the stack guard page. */ |
| 1852 | if (foll_flags & FOLL_MLOCK) { |
| 1853 | if (stack_guard_page(vma, start)) |
| 1854 | goto next_page; |
| 1855 | } |
| 1856 | if (foll_flags & FOLL_WRITE) |
| 1857 | fault_flags |= FAULT_FLAG_WRITE; |
| 1858 | if (nonblocking) |
| 1859 | fault_flags |= FAULT_FLAG_ALLOW_RETRY; |
| 1860 | if (foll_flags & FOLL_NOWAIT) |
| 1861 | fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); |
| 1862 | |
| 1863 | ret = handle_mm_fault(mm, vma, start, |
| 1864 | fault_flags); |
| 1865 | |
| 1866 | if (ret & VM_FAULT_ERROR) { |
| 1867 | if (ret & VM_FAULT_OOM) |
| 1868 | return i ? i : -ENOMEM; |
| 1869 | if (ret & (VM_FAULT_HWPOISON | |
| 1870 | VM_FAULT_HWPOISON_LARGE)) { |
| 1871 | if (i) |
| 1872 | return i; |
| 1873 | else if (gup_flags & FOLL_HWPOISON) |
| 1874 | return -EHWPOISON; |
| 1875 | else |
| 1876 | return -EFAULT; |
| 1877 | } |
| 1878 | if (ret & VM_FAULT_SIGBUS) |
| 1879 | goto efault; |
| 1880 | BUG(); |
| 1881 | } |
| 1882 | |
| 1883 | if (tsk) { |
| 1884 | if (ret & VM_FAULT_MAJOR) |
| 1885 | tsk->maj_flt++; |
| 1886 | else |
| 1887 | tsk->min_flt++; |
| 1888 | } |
| 1889 | |
| 1890 | if (ret & VM_FAULT_RETRY) { |
| 1891 | if (nonblocking) |
| 1892 | *nonblocking = 0; |
| 1893 | return i; |
| 1894 | } |
| 1895 | |
| 1896 | /* |
| 1897 | * The VM_FAULT_WRITE bit tells us that |
| 1898 | * do_wp_page has broken COW when necessary, |
| 1899 | * even if maybe_mkwrite decided not to set |
| 1900 | * pte_write. We can thus safely do subsequent |
| 1901 | * page lookups as if they were reads. But only |
| 1902 | * do so when looping for pte_write is futile: |
| 1903 | * in some cases userspace may also be wanting |
| 1904 | * to write to the gotten user page, which a |
| 1905 | * read fault here might prevent (a readonly |
| 1906 | * page might get reCOWed by userspace write). |
| 1907 | */ |
| 1908 | if ((ret & VM_FAULT_WRITE) && |
| 1909 | !(vma->vm_flags & VM_WRITE)) |
| 1910 | foll_flags &= ~FOLL_WRITE; |
| 1911 | |
| 1912 | cond_resched(); |
| 1913 | } |
| 1914 | if (IS_ERR(page)) |
| 1915 | return i ? i : PTR_ERR(page); |
| 1916 | if (pages) { |
| 1917 | pages[i] = page; |
| 1918 | |
| 1919 | flush_anon_page(vma, page, start); |
| 1920 | flush_dcache_page(page); |
| 1921 | page_mask = 0; |
| 1922 | } |
| 1923 | next_page: |
| 1924 | if (vmas) { |
| 1925 | vmas[i] = vma; |
| 1926 | page_mask = 0; |
| 1927 | } |
| 1928 | page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); |
| 1929 | if (page_increm > nr_pages) |
| 1930 | page_increm = nr_pages; |
| 1931 | i += page_increm; |
| 1932 | start += page_increm * PAGE_SIZE; |
| 1933 | nr_pages -= page_increm; |
| 1934 | } while (nr_pages && start < vma->vm_end); |
| 1935 | } while (nr_pages); |
| 1936 | return i; |
| 1937 | efault: |
| 1938 | return i ? : -EFAULT; |
| 1939 | } |
| 1940 | EXPORT_SYMBOL(__get_user_pages); |
| 1941 | |
| 1942 | /* |
| 1943 | * fixup_user_fault() - manually resolve a user page fault |
| 1944 | * @tsk: the task_struct to use for page fault accounting, or |
| 1945 | * NULL if faults are not to be recorded. |
| 1946 | * @mm: mm_struct of target mm |
| 1947 | * @address: user address |
| 1948 | * @fault_flags:flags to pass down to handle_mm_fault() |
| 1949 | * |
| 1950 | * This is meant to be called in the specific scenario where for locking reasons |
| 1951 | * we try to access user memory in atomic context (within a pagefault_disable() |
| 1952 | * section), this returns -EFAULT, and we want to resolve the user fault before |
| 1953 | * trying again. |
| 1954 | * |
| 1955 | * Typically this is meant to be used by the futex code. |
| 1956 | * |
| 1957 | * The main difference with get_user_pages() is that this function will |
| 1958 | * unconditionally call handle_mm_fault() which will in turn perform all the |
| 1959 | * necessary SW fixup of the dirty and young bits in the PTE, while |
| 1960 | * handle_mm_fault() only guarantees to update these in the struct page. |
| 1961 | * |
| 1962 | * This is important for some architectures where those bits also gate the |
| 1963 | * access permission to the page because they are maintained in software. On |
| 1964 | * such architectures, gup() will not be enough to make a subsequent access |
| 1965 | * succeed. |
| 1966 | * |
| 1967 | * This should be called with the mm_sem held for read. |
| 1968 | */ |
| 1969 | int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, |
| 1970 | unsigned long address, unsigned int fault_flags) |
| 1971 | { |
| 1972 | struct vm_area_struct *vma; |
| 1973 | vm_flags_t vm_flags; |
| 1974 | int ret; |
| 1975 | |
| 1976 | vma = find_extend_vma(mm, address); |
| 1977 | if (!vma || address < vma->vm_start) |
| 1978 | return -EFAULT; |
| 1979 | |
| 1980 | vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; |
| 1981 | if (!(vm_flags & vma->vm_flags)) |
| 1982 | return -EFAULT; |
| 1983 | |
| 1984 | ret = handle_mm_fault(mm, vma, address, fault_flags); |
| 1985 | if (ret & VM_FAULT_ERROR) { |
| 1986 | if (ret & VM_FAULT_OOM) |
| 1987 | return -ENOMEM; |
| 1988 | if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) |
| 1989 | return -EHWPOISON; |
| 1990 | if (ret & VM_FAULT_SIGBUS) |
| 1991 | return -EFAULT; |
| 1992 | BUG(); |
| 1993 | } |
| 1994 | if (tsk) { |
| 1995 | if (ret & VM_FAULT_MAJOR) |
| 1996 | tsk->maj_flt++; |
| 1997 | else |
| 1998 | tsk->min_flt++; |
| 1999 | } |
| 2000 | return 0; |
| 2001 | } |
| 2002 | |
| 2003 | /* |
| 2004 | * get_user_pages() - pin user pages in memory |
| 2005 | * @tsk: the task_struct to use for page fault accounting, or |
| 2006 | * NULL if faults are not to be recorded. |
| 2007 | * @mm: mm_struct of target mm |
| 2008 | * @start: starting user address |
| 2009 | * @nr_pages: number of pages from start to pin |
| 2010 | * @write: whether pages will be written to by the caller |
| 2011 | * @force: whether to force access even when user mapping is currently |
| 2012 | * protected (but never forces write access to shared mapping). |
| 2013 | * @pages: array that receives pointers to the pages pinned. |
| 2014 | * Should be at least nr_pages long. Or NULL, if caller |
| 2015 | * only intends to ensure the pages are faulted in. |
| 2016 | * @vmas: array of pointers to vmas corresponding to each page. |
| 2017 | * Or NULL if the caller does not require them. |
| 2018 | * |
| 2019 | * Returns number of pages pinned. This may be fewer than the number |
| 2020 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
| 2021 | * were pinned, returns -errno. Each page returned must be released |
| 2022 | * with a put_page() call when it is finished with. vmas will only |
| 2023 | * remain valid while mmap_sem is held. |
| 2024 | * |
| 2025 | * Must be called with mmap_sem held for read or write. |
| 2026 | * |
| 2027 | * get_user_pages walks a process's page tables and takes a reference to |
| 2028 | * each struct page that each user address corresponds to at a given |
| 2029 | * instant. That is, it takes the page that would be accessed if a user |
| 2030 | * thread accesses the given user virtual address at that instant. |
| 2031 | * |
| 2032 | * This does not guarantee that the page exists in the user mappings when |
| 2033 | * get_user_pages returns, and there may even be a completely different |
| 2034 | * page there in some cases (eg. if mmapped pagecache has been invalidated |
| 2035 | * and subsequently re faulted). However it does guarantee that the page |
| 2036 | * won't be freed completely. And mostly callers simply care that the page |
| 2037 | * contains data that was valid *at some point in time*. Typically, an IO |
| 2038 | * or similar operation cannot guarantee anything stronger anyway because |
| 2039 | * locks can't be held over the syscall boundary. |
| 2040 | * |
| 2041 | * If write=0, the page must not be written to. If the page is written to, |
| 2042 | * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called |
| 2043 | * after the page is finished with, and before put_page is called. |
| 2044 | * |
| 2045 | * get_user_pages is typically used for fewer-copy IO operations, to get a |
| 2046 | * handle on the memory by some means other than accesses via the user virtual |
| 2047 | * addresses. The pages may be submitted for DMA to devices or accessed via |
| 2048 | * their kernel linear mapping (via the kmap APIs). Care should be taken to |
| 2049 | * use the correct cache flushing APIs. |
| 2050 | * |
| 2051 | * See also get_user_pages_fast, for performance critical applications. |
| 2052 | */ |
| 2053 | long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
| 2054 | unsigned long start, unsigned long nr_pages, int write, |
| 2055 | int force, struct page **pages, struct vm_area_struct **vmas) |
| 2056 | { |
| 2057 | int flags = FOLL_TOUCH; |
| 2058 | |
| 2059 | if (pages) |
| 2060 | flags |= FOLL_GET; |
| 2061 | if (write) |
| 2062 | flags |= FOLL_WRITE; |
| 2063 | if (force) |
| 2064 | flags |= FOLL_FORCE; |
| 2065 | |
| 2066 | return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, |
| 2067 | NULL); |
| 2068 | } |
| 2069 | EXPORT_SYMBOL(get_user_pages); |
| 2070 | |
| 2071 | /** |
| 2072 | * get_dump_page() - pin user page in memory while writing it to core dump |
| 2073 | * @addr: user address |
| 2074 | * |
| 2075 | * Returns struct page pointer of user page pinned for dump, |
| 2076 | * to be freed afterwards by page_cache_release() or put_page(). |
| 2077 | * |
| 2078 | * Returns NULL on any kind of failure - a hole must then be inserted into |
| 2079 | * the corefile, to preserve alignment with its headers; and also returns |
| 2080 | * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - |
| 2081 | * allowing a hole to be left in the corefile to save diskspace. |
| 2082 | * |
| 2083 | * Called without mmap_sem, but after all other threads have been killed. |
| 2084 | */ |
| 2085 | #ifdef CONFIG_ELF_CORE |
| 2086 | struct page *get_dump_page(unsigned long addr) |
| 2087 | { |
| 2088 | struct vm_area_struct *vma; |
| 2089 | struct page *page; |
| 2090 | |
| 2091 | if (__get_user_pages(current, current->mm, addr, 1, |
| 2092 | FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, |
| 2093 | NULL) < 1) |
| 2094 | return NULL; |
| 2095 | flush_cache_page(vma, addr, page_to_pfn(page)); |
| 2096 | return page; |
| 2097 | } |
| 2098 | #endif /* CONFIG_ELF_CORE */ |
| 2099 | |
| 2100 | pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, |
| 2101 | spinlock_t **ptl) |
| 2102 | { |
| 2103 | pgd_t * pgd = pgd_offset(mm, addr); |
| 2104 | pud_t * pud = pud_alloc(mm, pgd, addr); |
| 2105 | if (pud) { |
| 2106 | pmd_t * pmd = pmd_alloc(mm, pud, addr); |
| 2107 | if (pmd) { |
| 2108 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
| 2109 | return pte_alloc_map_lock(mm, pmd, addr, ptl); |
| 2110 | } |
| 2111 | } |
| 2112 | return NULL; |
| 2113 | } |
| 2114 | |
| 2115 | /* |
| 2116 | * This is the old fallback for page remapping. |
| 2117 | * |
| 2118 | * For historical reasons, it only allows reserved pages. Only |
| 2119 | * old drivers should use this, and they needed to mark their |
| 2120 | * pages reserved for the old functions anyway. |
| 2121 | */ |
| 2122 | static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
| 2123 | struct page *page, pgprot_t prot) |
| 2124 | { |
| 2125 | struct mm_struct *mm = vma->vm_mm; |
| 2126 | int retval; |
| 2127 | pte_t *pte; |
| 2128 | spinlock_t *ptl; |
| 2129 | |
| 2130 | retval = -EINVAL; |
| 2131 | if (PageAnon(page)) |
| 2132 | goto out; |
| 2133 | retval = -ENOMEM; |
| 2134 | flush_dcache_page(page); |
| 2135 | pte = get_locked_pte(mm, addr, &ptl); |
| 2136 | if (!pte) |
| 2137 | goto out; |
| 2138 | retval = -EBUSY; |
| 2139 | if (!pte_none(*pte)) |
| 2140 | goto out_unlock; |
| 2141 | |
| 2142 | /* Ok, finally just insert the thing.. */ |
| 2143 | get_page(page); |
| 2144 | inc_mm_counter_fast(mm, MM_FILEPAGES); |
| 2145 | page_add_file_rmap(page); |
| 2146 | set_pte_at(mm, addr, pte, mk_pte(page, prot)); |
| 2147 | |
| 2148 | retval = 0; |
| 2149 | pte_unmap_unlock(pte, ptl); |
| 2150 | return retval; |
| 2151 | out_unlock: |
| 2152 | pte_unmap_unlock(pte, ptl); |
| 2153 | out: |
| 2154 | return retval; |
| 2155 | } |
| 2156 | |
| 2157 | /** |
| 2158 | * vm_insert_page - insert single page into user vma |
| 2159 | * @vma: user vma to map to |
| 2160 | * @addr: target user address of this page |
| 2161 | * @page: source kernel page |
| 2162 | * |
| 2163 | * This allows drivers to insert individual pages they've allocated |
| 2164 | * into a user vma. |
| 2165 | * |
| 2166 | * The page has to be a nice clean _individual_ kernel allocation. |
| 2167 | * If you allocate a compound page, you need to have marked it as |
| 2168 | * such (__GFP_COMP), or manually just split the page up yourself |
| 2169 | * (see split_page()). |
| 2170 | * |
| 2171 | * NOTE! Traditionally this was done with "remap_pfn_range()" which |
| 2172 | * took an arbitrary page protection parameter. This doesn't allow |
| 2173 | * that. Your vma protection will have to be set up correctly, which |
| 2174 | * means that if you want a shared writable mapping, you'd better |
| 2175 | * ask for a shared writable mapping! |
| 2176 | * |
| 2177 | * The page does not need to be reserved. |
| 2178 | * |
| 2179 | * Usually this function is called from f_op->mmap() handler |
| 2180 | * under mm->mmap_sem write-lock, so it can change vma->vm_flags. |
| 2181 | * Caller must set VM_MIXEDMAP on vma if it wants to call this |
| 2182 | * function from other places, for example from page-fault handler. |
| 2183 | */ |
| 2184 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
| 2185 | struct page *page) |
| 2186 | { |
| 2187 | if (addr < vma->vm_start || addr >= vma->vm_end) |
| 2188 | return -EFAULT; |
| 2189 | if (!page_count(page)) |
| 2190 | return -EINVAL; |
| 2191 | if (!(vma->vm_flags & VM_MIXEDMAP)) { |
| 2192 | BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); |
| 2193 | BUG_ON(vma->vm_flags & VM_PFNMAP); |
| 2194 | vma->vm_flags |= VM_MIXEDMAP; |
| 2195 | } |
| 2196 | return insert_page(vma, addr, page, vma->vm_page_prot); |
| 2197 | } |
| 2198 | EXPORT_SYMBOL(vm_insert_page); |
| 2199 | |
| 2200 | static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| 2201 | unsigned long pfn, pgprot_t prot) |
| 2202 | { |
| 2203 | struct mm_struct *mm = vma->vm_mm; |
| 2204 | int retval; |
| 2205 | pte_t *pte, entry; |
| 2206 | spinlock_t *ptl; |
| 2207 | |
| 2208 | retval = -ENOMEM; |
| 2209 | pte = get_locked_pte(mm, addr, &ptl); |
| 2210 | if (!pte) |
| 2211 | goto out; |
| 2212 | retval = -EBUSY; |
| 2213 | if (!pte_none(*pte)) |
| 2214 | goto out_unlock; |
| 2215 | |
| 2216 | /* Ok, finally just insert the thing.. */ |
| 2217 | entry = pte_mkspecial(pfn_pte(pfn, prot)); |
| 2218 | set_pte_at(mm, addr, pte, entry); |
| 2219 | update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ |
| 2220 | |
| 2221 | retval = 0; |
| 2222 | out_unlock: |
| 2223 | pte_unmap_unlock(pte, ptl); |
| 2224 | out: |
| 2225 | return retval; |
| 2226 | } |
| 2227 | |
| 2228 | /** |
| 2229 | * vm_insert_pfn - insert single pfn into user vma |
| 2230 | * @vma: user vma to map to |
| 2231 | * @addr: target user address of this page |
| 2232 | * @pfn: source kernel pfn |
| 2233 | * |
| 2234 | * Similar to vm_insert_page, this allows drivers to insert individual pages |
| 2235 | * they've allocated into a user vma. Same comments apply. |
| 2236 | * |
| 2237 | * This function should only be called from a vm_ops->fault handler, and |
| 2238 | * in that case the handler should return NULL. |
| 2239 | * |
| 2240 | * vma cannot be a COW mapping. |
| 2241 | * |
| 2242 | * As this is called only for pages that do not currently exist, we |
| 2243 | * do not need to flush old virtual caches or the TLB. |
| 2244 | */ |
| 2245 | int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| 2246 | unsigned long pfn) |
| 2247 | { |
| 2248 | int ret; |
| 2249 | pgprot_t pgprot = vma->vm_page_prot; |
| 2250 | /* |
| 2251 | * Technically, architectures with pte_special can avoid all these |
| 2252 | * restrictions (same for remap_pfn_range). However we would like |
| 2253 | * consistency in testing and feature parity among all, so we should |
| 2254 | * try to keep these invariants in place for everybody. |
| 2255 | */ |
| 2256 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
| 2257 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
| 2258 | (VM_PFNMAP|VM_MIXEDMAP)); |
| 2259 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
| 2260 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
| 2261 | |
| 2262 | if (addr < vma->vm_start || addr >= vma->vm_end) |
| 2263 | return -EFAULT; |
| 2264 | if (track_pfn_insert(vma, &pgprot, pfn)) |
| 2265 | return -EINVAL; |
| 2266 | |
| 2267 | ret = insert_pfn(vma, addr, pfn, pgprot); |
| 2268 | |
| 2269 | return ret; |
| 2270 | } |
| 2271 | EXPORT_SYMBOL(vm_insert_pfn); |
| 2272 | |
| 2273 | int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
| 2274 | unsigned long pfn) |
| 2275 | { |
| 2276 | BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); |
| 2277 | |
| 2278 | if (addr < vma->vm_start || addr >= vma->vm_end) |
| 2279 | return -EFAULT; |
| 2280 | |
| 2281 | /* |
| 2282 | * If we don't have pte special, then we have to use the pfn_valid() |
| 2283 | * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
| 2284 | * refcount the page if pfn_valid is true (hence insert_page rather |
| 2285 | * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
| 2286 | * without pte special, it would there be refcounted as a normal page. |
| 2287 | */ |
| 2288 | if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { |
| 2289 | struct page *page; |
| 2290 | |
| 2291 | page = pfn_to_page(pfn); |
| 2292 | return insert_page(vma, addr, page, vma->vm_page_prot); |
| 2293 | } |
| 2294 | return insert_pfn(vma, addr, pfn, vma->vm_page_prot); |
| 2295 | } |
| 2296 | EXPORT_SYMBOL(vm_insert_mixed); |
| 2297 | |
| 2298 | /* |
| 2299 | * maps a range of physical memory into the requested pages. the old |
| 2300 | * mappings are removed. any references to nonexistent pages results |
| 2301 | * in null mappings (currently treated as "copy-on-access") |
| 2302 | */ |
| 2303 | static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| 2304 | unsigned long addr, unsigned long end, |
| 2305 | unsigned long pfn, pgprot_t prot) |
| 2306 | { |
| 2307 | pte_t *pte; |
| 2308 | spinlock_t *ptl; |
| 2309 | |
| 2310 | pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| 2311 | if (!pte) |
| 2312 | return -ENOMEM; |
| 2313 | arch_enter_lazy_mmu_mode(); |
| 2314 | do { |
| 2315 | BUG_ON(!pte_none(*pte)); |
| 2316 | set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
| 2317 | pfn++; |
| 2318 | } while (pte++, addr += PAGE_SIZE, addr != end); |
| 2319 | arch_leave_lazy_mmu_mode(); |
| 2320 | pte_unmap_unlock(pte - 1, ptl); |
| 2321 | return 0; |
| 2322 | } |
| 2323 | |
| 2324 | static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
| 2325 | unsigned long addr, unsigned long end, |
| 2326 | unsigned long pfn, pgprot_t prot) |
| 2327 | { |
| 2328 | pmd_t *pmd; |
| 2329 | unsigned long next; |
| 2330 | |
| 2331 | pfn -= addr >> PAGE_SHIFT; |
| 2332 | pmd = pmd_alloc(mm, pud, addr); |
| 2333 | if (!pmd) |
| 2334 | return -ENOMEM; |
| 2335 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
| 2336 | do { |
| 2337 | next = pmd_addr_end(addr, end); |
| 2338 | if (remap_pte_range(mm, pmd, addr, next, |
| 2339 | pfn + (addr >> PAGE_SHIFT), prot)) |
| 2340 | return -ENOMEM; |
| 2341 | } while (pmd++, addr = next, addr != end); |
| 2342 | return 0; |
| 2343 | } |
| 2344 | |
| 2345 | static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, |
| 2346 | unsigned long addr, unsigned long end, |
| 2347 | unsigned long pfn, pgprot_t prot) |
| 2348 | { |
| 2349 | pud_t *pud; |
| 2350 | unsigned long next; |
| 2351 | |
| 2352 | pfn -= addr >> PAGE_SHIFT; |
| 2353 | pud = pud_alloc(mm, pgd, addr); |
| 2354 | if (!pud) |
| 2355 | return -ENOMEM; |
| 2356 | do { |
| 2357 | next = pud_addr_end(addr, end); |
| 2358 | if (remap_pmd_range(mm, pud, addr, next, |
| 2359 | pfn + (addr >> PAGE_SHIFT), prot)) |
| 2360 | return -ENOMEM; |
| 2361 | } while (pud++, addr = next, addr != end); |
| 2362 | return 0; |
| 2363 | } |
| 2364 | |
| 2365 | /** |
| 2366 | * remap_pfn_range - remap kernel memory to userspace |
| 2367 | * @vma: user vma to map to |
| 2368 | * @addr: target user address to start at |
| 2369 | * @pfn: physical address of kernel memory |
| 2370 | * @size: size of map area |
| 2371 | * @prot: page protection flags for this mapping |
| 2372 | * |
| 2373 | * Note: this is only safe if the mm semaphore is held when called. |
| 2374 | */ |
| 2375 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
| 2376 | unsigned long pfn, unsigned long size, pgprot_t prot) |
| 2377 | { |
| 2378 | pgd_t *pgd; |
| 2379 | unsigned long next; |
| 2380 | unsigned long end = addr + PAGE_ALIGN(size); |
| 2381 | struct mm_struct *mm = vma->vm_mm; |
| 2382 | int err; |
| 2383 | |
| 2384 | /* |
| 2385 | * Physically remapped pages are special. Tell the |
| 2386 | * rest of the world about it: |
| 2387 | * VM_IO tells people not to look at these pages |
| 2388 | * (accesses can have side effects). |
| 2389 | * VM_PFNMAP tells the core MM that the base pages are just |
| 2390 | * raw PFN mappings, and do not have a "struct page" associated |
| 2391 | * with them. |
| 2392 | * VM_DONTEXPAND |
| 2393 | * Disable vma merging and expanding with mremap(). |
| 2394 | * VM_DONTDUMP |
| 2395 | * Omit vma from core dump, even when VM_IO turned off. |
| 2396 | * |
| 2397 | * There's a horrible special case to handle copy-on-write |
| 2398 | * behaviour that some programs depend on. We mark the "original" |
| 2399 | * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
| 2400 | * See vm_normal_page() for details. |
| 2401 | */ |
| 2402 | if (is_cow_mapping(vma->vm_flags)) { |
| 2403 | if (addr != vma->vm_start || end != vma->vm_end) |
| 2404 | return -EINVAL; |
| 2405 | vma->vm_pgoff = pfn; |
| 2406 | } |
| 2407 | |
| 2408 | err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); |
| 2409 | if (err) |
| 2410 | return -EINVAL; |
| 2411 | |
| 2412 | vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
| 2413 | |
| 2414 | BUG_ON(addr >= end); |
| 2415 | pfn -= addr >> PAGE_SHIFT; |
| 2416 | pgd = pgd_offset(mm, addr); |
| 2417 | flush_cache_range(vma, addr, end); |
| 2418 | do { |
| 2419 | next = pgd_addr_end(addr, end); |
| 2420 | err = remap_pud_range(mm, pgd, addr, next, |
| 2421 | pfn + (addr >> PAGE_SHIFT), prot); |
| 2422 | if (err) |
| 2423 | break; |
| 2424 | } while (pgd++, addr = next, addr != end); |
| 2425 | |
| 2426 | if (err) |
| 2427 | untrack_pfn(vma, pfn, PAGE_ALIGN(size)); |
| 2428 | |
| 2429 | return err; |
| 2430 | } |
| 2431 | EXPORT_SYMBOL(remap_pfn_range); |
| 2432 | |
| 2433 | /** |
| 2434 | * vm_iomap_memory - remap memory to userspace |
| 2435 | * @vma: user vma to map to |
| 2436 | * @start: start of area |
| 2437 | * @len: size of area |
| 2438 | * |
| 2439 | * This is a simplified io_remap_pfn_range() for common driver use. The |
| 2440 | * driver just needs to give us the physical memory range to be mapped, |
| 2441 | * we'll figure out the rest from the vma information. |
| 2442 | * |
| 2443 | * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get |
| 2444 | * whatever write-combining details or similar. |
| 2445 | */ |
| 2446 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
| 2447 | { |
| 2448 | unsigned long vm_len, pfn, pages; |
| 2449 | |
| 2450 | /* Check that the physical memory area passed in looks valid */ |
| 2451 | if (start + len < start) |
| 2452 | return -EINVAL; |
| 2453 | /* |
| 2454 | * You *really* shouldn't map things that aren't page-aligned, |
| 2455 | * but we've historically allowed it because IO memory might |
| 2456 | * just have smaller alignment. |
| 2457 | */ |
| 2458 | len += start & ~PAGE_MASK; |
| 2459 | pfn = start >> PAGE_SHIFT; |
| 2460 | pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; |
| 2461 | if (pfn + pages < pfn) |
| 2462 | return -EINVAL; |
| 2463 | |
| 2464 | /* We start the mapping 'vm_pgoff' pages into the area */ |
| 2465 | if (vma->vm_pgoff > pages) |
| 2466 | return -EINVAL; |
| 2467 | pfn += vma->vm_pgoff; |
| 2468 | pages -= vma->vm_pgoff; |
| 2469 | |
| 2470 | /* Can we fit all of the mapping? */ |
| 2471 | vm_len = vma->vm_end - vma->vm_start; |
| 2472 | if (vm_len >> PAGE_SHIFT > pages) |
| 2473 | return -EINVAL; |
| 2474 | |
| 2475 | /* Ok, let it rip */ |
| 2476 | return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
| 2477 | } |
| 2478 | EXPORT_SYMBOL(vm_iomap_memory); |
| 2479 | |
| 2480 | static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| 2481 | unsigned long addr, unsigned long end, |
| 2482 | pte_fn_t fn, void *data) |
| 2483 | { |
| 2484 | pte_t *pte; |
| 2485 | int err; |
| 2486 | pgtable_t token; |
| 2487 | spinlock_t *uninitialized_var(ptl); |
| 2488 | |
| 2489 | pte = (mm == &init_mm) ? |
| 2490 | pte_alloc_kernel(pmd, addr) : |
| 2491 | pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| 2492 | if (!pte) |
| 2493 | return -ENOMEM; |
| 2494 | |
| 2495 | BUG_ON(pmd_huge(*pmd)); |
| 2496 | |
| 2497 | arch_enter_lazy_mmu_mode(); |
| 2498 | |
| 2499 | token = pmd_pgtable(*pmd); |
| 2500 | |
| 2501 | do { |
| 2502 | err = fn(pte++, token, addr, data); |
| 2503 | if (err) |
| 2504 | break; |
| 2505 | } while (addr += PAGE_SIZE, addr != end); |
| 2506 | |
| 2507 | arch_leave_lazy_mmu_mode(); |
| 2508 | |
| 2509 | if (mm != &init_mm) |
| 2510 | pte_unmap_unlock(pte-1, ptl); |
| 2511 | return err; |
| 2512 | } |
| 2513 | |
| 2514 | static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
| 2515 | unsigned long addr, unsigned long end, |
| 2516 | pte_fn_t fn, void *data) |
| 2517 | { |
| 2518 | pmd_t *pmd; |
| 2519 | unsigned long next; |
| 2520 | int err; |
| 2521 | |
| 2522 | BUG_ON(pud_huge(*pud)); |
| 2523 | |
| 2524 | pmd = pmd_alloc(mm, pud, addr); |
| 2525 | if (!pmd) |
| 2526 | return -ENOMEM; |
| 2527 | do { |
| 2528 | next = pmd_addr_end(addr, end); |
| 2529 | err = apply_to_pte_range(mm, pmd, addr, next, fn, data); |
| 2530 | if (err) |
| 2531 | break; |
| 2532 | } while (pmd++, addr = next, addr != end); |
| 2533 | return err; |
| 2534 | } |
| 2535 | |
| 2536 | static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, |
| 2537 | unsigned long addr, unsigned long end, |
| 2538 | pte_fn_t fn, void *data) |
| 2539 | { |
| 2540 | pud_t *pud; |
| 2541 | unsigned long next; |
| 2542 | int err; |
| 2543 | |
| 2544 | pud = pud_alloc(mm, pgd, addr); |
| 2545 | if (!pud) |
| 2546 | return -ENOMEM; |
| 2547 | do { |
| 2548 | next = pud_addr_end(addr, end); |
| 2549 | err = apply_to_pmd_range(mm, pud, addr, next, fn, data); |
| 2550 | if (err) |
| 2551 | break; |
| 2552 | } while (pud++, addr = next, addr != end); |
| 2553 | return err; |
| 2554 | } |
| 2555 | |
| 2556 | /* |
| 2557 | * Scan a region of virtual memory, filling in page tables as necessary |
| 2558 | * and calling a provided function on each leaf page table. |
| 2559 | */ |
| 2560 | int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| 2561 | unsigned long size, pte_fn_t fn, void *data) |
| 2562 | { |
| 2563 | pgd_t *pgd; |
| 2564 | unsigned long next; |
| 2565 | unsigned long end = addr + size; |
| 2566 | int err; |
| 2567 | |
| 2568 | BUG_ON(addr >= end); |
| 2569 | pgd = pgd_offset(mm, addr); |
| 2570 | do { |
| 2571 | next = pgd_addr_end(addr, end); |
| 2572 | err = apply_to_pud_range(mm, pgd, addr, next, fn, data); |
| 2573 | if (err) |
| 2574 | break; |
| 2575 | } while (pgd++, addr = next, addr != end); |
| 2576 | |
| 2577 | return err; |
| 2578 | } |
| 2579 | EXPORT_SYMBOL_GPL(apply_to_page_range); |
| 2580 | |
| 2581 | /* |
| 2582 | * handle_pte_fault chooses page fault handler according to an entry |
| 2583 | * which was read non-atomically. Before making any commitment, on |
| 2584 | * those architectures or configurations (e.g. i386 with PAE) which |
| 2585 | * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault |
| 2586 | * must check under lock before unmapping the pte and proceeding |
| 2587 | * (but do_wp_page is only called after already making such a check; |
| 2588 | * and do_anonymous_page can safely check later on). |
| 2589 | */ |
| 2590 | static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, |
| 2591 | pte_t *page_table, pte_t orig_pte) |
| 2592 | { |
| 2593 | int same = 1; |
| 2594 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) |
| 2595 | if (sizeof(pte_t) > sizeof(unsigned long)) { |
| 2596 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
| 2597 | spin_lock(ptl); |
| 2598 | same = pte_same(*page_table, orig_pte); |
| 2599 | spin_unlock(ptl); |
| 2600 | } |
| 2601 | #endif |
| 2602 | pte_unmap(page_table); |
| 2603 | return same; |
| 2604 | } |
| 2605 | |
| 2606 | static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) |
| 2607 | { |
| 2608 | debug_dma_assert_idle(src); |
| 2609 | |
| 2610 | /* |
| 2611 | * If the source page was a PFN mapping, we don't have |
| 2612 | * a "struct page" for it. We do a best-effort copy by |
| 2613 | * just copying from the original user address. If that |
| 2614 | * fails, we just zero-fill it. Live with it. |
| 2615 | */ |
| 2616 | if (unlikely(!src)) { |
| 2617 | void *kaddr = kmap_atomic(dst); |
| 2618 | void __user *uaddr = (void __user *)(va & PAGE_MASK); |
| 2619 | |
| 2620 | /* |
| 2621 | * This really shouldn't fail, because the page is there |
| 2622 | * in the page tables. But it might just be unreadable, |
| 2623 | * in which case we just give up and fill the result with |
| 2624 | * zeroes. |
| 2625 | */ |
| 2626 | if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) |
| 2627 | clear_page(kaddr); |
| 2628 | kunmap_atomic(kaddr); |
| 2629 | flush_dcache_page(dst); |
| 2630 | } else |
| 2631 | copy_user_highpage(dst, src, va, vma); |
| 2632 | } |
| 2633 | |
| 2634 | /* |
| 2635 | * Notify the address space that the page is about to become writable so that |
| 2636 | * it can prohibit this or wait for the page to get into an appropriate state. |
| 2637 | * |
| 2638 | * We do this without the lock held, so that it can sleep if it needs to. |
| 2639 | */ |
| 2640 | static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page, |
| 2641 | unsigned long address) |
| 2642 | { |
| 2643 | struct vm_fault vmf; |
| 2644 | int ret; |
| 2645 | |
| 2646 | vmf.virtual_address = (void __user *)(address & PAGE_MASK); |
| 2647 | vmf.pgoff = page->index; |
| 2648 | vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
| 2649 | vmf.page = page; |
| 2650 | |
| 2651 | ret = vma->vm_ops->page_mkwrite(vma, &vmf); |
| 2652 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) |
| 2653 | return ret; |
| 2654 | if (unlikely(!(ret & VM_FAULT_LOCKED))) { |
| 2655 | lock_page(page); |
| 2656 | if (!page->mapping) { |
| 2657 | unlock_page(page); |
| 2658 | return 0; /* retry */ |
| 2659 | } |
| 2660 | ret |= VM_FAULT_LOCKED; |
| 2661 | } else |
| 2662 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
| 2663 | return ret; |
| 2664 | } |
| 2665 | |
| 2666 | /* |
| 2667 | * This routine handles present pages, when users try to write |
| 2668 | * to a shared page. It is done by copying the page to a new address |
| 2669 | * and decrementing the shared-page counter for the old page. |
| 2670 | * |
| 2671 | * Note that this routine assumes that the protection checks have been |
| 2672 | * done by the caller (the low-level page fault routine in most cases). |
| 2673 | * Thus we can safely just mark it writable once we've done any necessary |
| 2674 | * COW. |
| 2675 | * |
| 2676 | * We also mark the page dirty at this point even though the page will |
| 2677 | * change only once the write actually happens. This avoids a few races, |
| 2678 | * and potentially makes it more efficient. |
| 2679 | * |
| 2680 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| 2681 | * but allow concurrent faults), with pte both mapped and locked. |
| 2682 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
| 2683 | */ |
| 2684 | static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 2685 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
| 2686 | spinlock_t *ptl, pte_t orig_pte) |
| 2687 | __releases(ptl) |
| 2688 | { |
| 2689 | struct page *old_page, *new_page = NULL; |
| 2690 | pte_t entry; |
| 2691 | int ret = 0; |
| 2692 | int page_mkwrite = 0; |
| 2693 | struct page *dirty_page = NULL; |
| 2694 | unsigned long mmun_start = 0; /* For mmu_notifiers */ |
| 2695 | unsigned long mmun_end = 0; /* For mmu_notifiers */ |
| 2696 | |
| 2697 | old_page = vm_normal_page(vma, address, orig_pte); |
| 2698 | if (!old_page) { |
| 2699 | /* |
| 2700 | * VM_MIXEDMAP !pfn_valid() case |
| 2701 | * |
| 2702 | * We should not cow pages in a shared writeable mapping. |
| 2703 | * Just mark the pages writable as we can't do any dirty |
| 2704 | * accounting on raw pfn maps. |
| 2705 | */ |
| 2706 | if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| 2707 | (VM_WRITE|VM_SHARED)) |
| 2708 | goto reuse; |
| 2709 | goto gotten; |
| 2710 | } |
| 2711 | |
| 2712 | /* |
| 2713 | * Take out anonymous pages first, anonymous shared vmas are |
| 2714 | * not dirty accountable. |
| 2715 | */ |
| 2716 | if (PageAnon(old_page) && !PageKsm(old_page)) { |
| 2717 | if (!trylock_page(old_page)) { |
| 2718 | page_cache_get(old_page); |
| 2719 | pte_unmap_unlock(page_table, ptl); |
| 2720 | lock_page(old_page); |
| 2721 | page_table = pte_offset_map_lock(mm, pmd, address, |
| 2722 | &ptl); |
| 2723 | if (!pte_same(*page_table, orig_pte)) { |
| 2724 | unlock_page(old_page); |
| 2725 | goto unlock; |
| 2726 | } |
| 2727 | page_cache_release(old_page); |
| 2728 | } |
| 2729 | if (reuse_swap_page(old_page)) { |
| 2730 | /* |
| 2731 | * The page is all ours. Move it to our anon_vma so |
| 2732 | * the rmap code will not search our parent or siblings. |
| 2733 | * Protected against the rmap code by the page lock. |
| 2734 | */ |
| 2735 | page_move_anon_rmap(old_page, vma, address); |
| 2736 | unlock_page(old_page); |
| 2737 | goto reuse; |
| 2738 | } |
| 2739 | unlock_page(old_page); |
| 2740 | } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| 2741 | (VM_WRITE|VM_SHARED))) { |
| 2742 | /* |
| 2743 | * Only catch write-faults on shared writable pages, |
| 2744 | * read-only shared pages can get COWed by |
| 2745 | * get_user_pages(.write=1, .force=1). |
| 2746 | */ |
| 2747 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) { |
| 2748 | int tmp; |
| 2749 | page_cache_get(old_page); |
| 2750 | pte_unmap_unlock(page_table, ptl); |
| 2751 | tmp = do_page_mkwrite(vma, old_page, address); |
| 2752 | if (unlikely(!tmp || (tmp & |
| 2753 | (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
| 2754 | page_cache_release(old_page); |
| 2755 | return tmp; |
| 2756 | } |
| 2757 | /* |
| 2758 | * Since we dropped the lock we need to revalidate |
| 2759 | * the PTE as someone else may have changed it. If |
| 2760 | * they did, we just return, as we can count on the |
| 2761 | * MMU to tell us if they didn't also make it writable. |
| 2762 | */ |
| 2763 | page_table = pte_offset_map_lock(mm, pmd, address, |
| 2764 | &ptl); |
| 2765 | if (!pte_same(*page_table, orig_pte)) { |
| 2766 | unlock_page(old_page); |
| 2767 | goto unlock; |
| 2768 | } |
| 2769 | |
| 2770 | page_mkwrite = 1; |
| 2771 | } |
| 2772 | dirty_page = old_page; |
| 2773 | get_page(dirty_page); |
| 2774 | |
| 2775 | reuse: |
| 2776 | /* |
| 2777 | * Clear the pages cpupid information as the existing |
| 2778 | * information potentially belongs to a now completely |
| 2779 | * unrelated process. |
| 2780 | */ |
| 2781 | if (old_page) |
| 2782 | page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1); |
| 2783 | |
| 2784 | flush_cache_page(vma, address, pte_pfn(orig_pte)); |
| 2785 | entry = pte_mkyoung(orig_pte); |
| 2786 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| 2787 | if (ptep_set_access_flags(vma, address, page_table, entry,1)) |
| 2788 | update_mmu_cache(vma, address, page_table); |
| 2789 | pte_unmap_unlock(page_table, ptl); |
| 2790 | ret |= VM_FAULT_WRITE; |
| 2791 | |
| 2792 | if (!dirty_page) |
| 2793 | return ret; |
| 2794 | |
| 2795 | /* |
| 2796 | * Yes, Virginia, this is actually required to prevent a race |
| 2797 | * with clear_page_dirty_for_io() from clearing the page dirty |
| 2798 | * bit after it clear all dirty ptes, but before a racing |
| 2799 | * do_wp_page installs a dirty pte. |
| 2800 | * |
| 2801 | * do_shared_fault is protected similarly. |
| 2802 | */ |
| 2803 | if (!page_mkwrite) { |
| 2804 | wait_on_page_locked(dirty_page); |
| 2805 | set_page_dirty_balance(dirty_page); |
| 2806 | /* file_update_time outside page_lock */ |
| 2807 | if (vma->vm_file) |
| 2808 | file_update_time(vma->vm_file); |
| 2809 | } |
| 2810 | put_page(dirty_page); |
| 2811 | if (page_mkwrite) { |
| 2812 | struct address_space *mapping = dirty_page->mapping; |
| 2813 | |
| 2814 | set_page_dirty(dirty_page); |
| 2815 | unlock_page(dirty_page); |
| 2816 | page_cache_release(dirty_page); |
| 2817 | if (mapping) { |
| 2818 | /* |
| 2819 | * Some device drivers do not set page.mapping |
| 2820 | * but still dirty their pages |
| 2821 | */ |
| 2822 | balance_dirty_pages_ratelimited(mapping); |
| 2823 | } |
| 2824 | } |
| 2825 | |
| 2826 | return ret; |
| 2827 | } |
| 2828 | |
| 2829 | /* |
| 2830 | * Ok, we need to copy. Oh, well.. |
| 2831 | */ |
| 2832 | page_cache_get(old_page); |
| 2833 | gotten: |
| 2834 | pte_unmap_unlock(page_table, ptl); |
| 2835 | |
| 2836 | if (unlikely(anon_vma_prepare(vma))) |
| 2837 | goto oom; |
| 2838 | |
| 2839 | if (is_zero_pfn(pte_pfn(orig_pte))) { |
| 2840 | new_page = alloc_zeroed_user_highpage_movable(vma, address); |
| 2841 | if (!new_page) |
| 2842 | goto oom; |
| 2843 | } else { |
| 2844 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
| 2845 | if (!new_page) |
| 2846 | goto oom; |
| 2847 | cow_user_page(new_page, old_page, address, vma); |
| 2848 | } |
| 2849 | __SetPageUptodate(new_page); |
| 2850 | |
| 2851 | if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) |
| 2852 | goto oom_free_new; |
| 2853 | |
| 2854 | mmun_start = address & PAGE_MASK; |
| 2855 | mmun_end = mmun_start + PAGE_SIZE; |
| 2856 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| 2857 | |
| 2858 | /* |
| 2859 | * Re-check the pte - we dropped the lock |
| 2860 | */ |
| 2861 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 2862 | if (likely(pte_same(*page_table, orig_pte))) { |
| 2863 | if (old_page) { |
| 2864 | if (!PageAnon(old_page)) { |
| 2865 | dec_mm_counter_fast(mm, MM_FILEPAGES); |
| 2866 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
| 2867 | } |
| 2868 | } else |
| 2869 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
| 2870 | flush_cache_page(vma, address, pte_pfn(orig_pte)); |
| 2871 | entry = mk_pte(new_page, vma->vm_page_prot); |
| 2872 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| 2873 | /* |
| 2874 | * Clear the pte entry and flush it first, before updating the |
| 2875 | * pte with the new entry. This will avoid a race condition |
| 2876 | * seen in the presence of one thread doing SMC and another |
| 2877 | * thread doing COW. |
| 2878 | */ |
| 2879 | ptep_clear_flush(vma, address, page_table); |
| 2880 | page_add_new_anon_rmap(new_page, vma, address); |
| 2881 | /* |
| 2882 | * We call the notify macro here because, when using secondary |
| 2883 | * mmu page tables (such as kvm shadow page tables), we want the |
| 2884 | * new page to be mapped directly into the secondary page table. |
| 2885 | */ |
| 2886 | set_pte_at_notify(mm, address, page_table, entry); |
| 2887 | update_mmu_cache(vma, address, page_table); |
| 2888 | if (old_page) { |
| 2889 | /* |
| 2890 | * Only after switching the pte to the new page may |
| 2891 | * we remove the mapcount here. Otherwise another |
| 2892 | * process may come and find the rmap count decremented |
| 2893 | * before the pte is switched to the new page, and |
| 2894 | * "reuse" the old page writing into it while our pte |
| 2895 | * here still points into it and can be read by other |
| 2896 | * threads. |
| 2897 | * |
| 2898 | * The critical issue is to order this |
| 2899 | * page_remove_rmap with the ptp_clear_flush above. |
| 2900 | * Those stores are ordered by (if nothing else,) |
| 2901 | * the barrier present in the atomic_add_negative |
| 2902 | * in page_remove_rmap. |
| 2903 | * |
| 2904 | * Then the TLB flush in ptep_clear_flush ensures that |
| 2905 | * no process can access the old page before the |
| 2906 | * decremented mapcount is visible. And the old page |
| 2907 | * cannot be reused until after the decremented |
| 2908 | * mapcount is visible. So transitively, TLBs to |
| 2909 | * old page will be flushed before it can be reused. |
| 2910 | */ |
| 2911 | page_remove_rmap(old_page); |
| 2912 | } |
| 2913 | |
| 2914 | /* Free the old page.. */ |
| 2915 | new_page = old_page; |
| 2916 | ret |= VM_FAULT_WRITE; |
| 2917 | } else |
| 2918 | mem_cgroup_uncharge_page(new_page); |
| 2919 | |
| 2920 | if (new_page) |
| 2921 | page_cache_release(new_page); |
| 2922 | unlock: |
| 2923 | pte_unmap_unlock(page_table, ptl); |
| 2924 | if (mmun_end > mmun_start) |
| 2925 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| 2926 | if (old_page) { |
| 2927 | /* |
| 2928 | * Don't let another task, with possibly unlocked vma, |
| 2929 | * keep the mlocked page. |
| 2930 | */ |
| 2931 | if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { |
| 2932 | lock_page(old_page); /* LRU manipulation */ |
| 2933 | munlock_vma_page(old_page); |
| 2934 | unlock_page(old_page); |
| 2935 | } |
| 2936 | page_cache_release(old_page); |
| 2937 | } |
| 2938 | return ret; |
| 2939 | oom_free_new: |
| 2940 | page_cache_release(new_page); |
| 2941 | oom: |
| 2942 | if (old_page) |
| 2943 | page_cache_release(old_page); |
| 2944 | return VM_FAULT_OOM; |
| 2945 | } |
| 2946 | |
| 2947 | static void unmap_mapping_range_vma(struct vm_area_struct *vma, |
| 2948 | unsigned long start_addr, unsigned long end_addr, |
| 2949 | struct zap_details *details) |
| 2950 | { |
| 2951 | zap_page_range_single(vma, start_addr, end_addr - start_addr, details); |
| 2952 | } |
| 2953 | |
| 2954 | static inline void unmap_mapping_range_tree(struct rb_root *root, |
| 2955 | struct zap_details *details) |
| 2956 | { |
| 2957 | struct vm_area_struct *vma; |
| 2958 | pgoff_t vba, vea, zba, zea; |
| 2959 | |
| 2960 | vma_interval_tree_foreach(vma, root, |
| 2961 | details->first_index, details->last_index) { |
| 2962 | |
| 2963 | vba = vma->vm_pgoff; |
| 2964 | vea = vba + vma_pages(vma) - 1; |
| 2965 | /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ |
| 2966 | zba = details->first_index; |
| 2967 | if (zba < vba) |
| 2968 | zba = vba; |
| 2969 | zea = details->last_index; |
| 2970 | if (zea > vea) |
| 2971 | zea = vea; |
| 2972 | |
| 2973 | unmap_mapping_range_vma(vma, |
| 2974 | ((zba - vba) << PAGE_SHIFT) + vma->vm_start, |
| 2975 | ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, |
| 2976 | details); |
| 2977 | } |
| 2978 | } |
| 2979 | |
| 2980 | static inline void unmap_mapping_range_list(struct list_head *head, |
| 2981 | struct zap_details *details) |
| 2982 | { |
| 2983 | struct vm_area_struct *vma; |
| 2984 | |
| 2985 | /* |
| 2986 | * In nonlinear VMAs there is no correspondence between virtual address |
| 2987 | * offset and file offset. So we must perform an exhaustive search |
| 2988 | * across *all* the pages in each nonlinear VMA, not just the pages |
| 2989 | * whose virtual address lies outside the file truncation point. |
| 2990 | */ |
| 2991 | list_for_each_entry(vma, head, shared.nonlinear) { |
| 2992 | details->nonlinear_vma = vma; |
| 2993 | unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); |
| 2994 | } |
| 2995 | } |
| 2996 | |
| 2997 | /** |
| 2998 | * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. |
| 2999 | * @mapping: the address space containing mmaps to be unmapped. |
| 3000 | * @holebegin: byte in first page to unmap, relative to the start of |
| 3001 | * the underlying file. This will be rounded down to a PAGE_SIZE |
| 3002 | * boundary. Note that this is different from truncate_pagecache(), which |
| 3003 | * must keep the partial page. In contrast, we must get rid of |
| 3004 | * partial pages. |
| 3005 | * @holelen: size of prospective hole in bytes. This will be rounded |
| 3006 | * up to a PAGE_SIZE boundary. A holelen of zero truncates to the |
| 3007 | * end of the file. |
| 3008 | * @even_cows: 1 when truncating a file, unmap even private COWed pages; |
| 3009 | * but 0 when invalidating pagecache, don't throw away private data. |
| 3010 | */ |
| 3011 | void unmap_mapping_range(struct address_space *mapping, |
| 3012 | loff_t const holebegin, loff_t const holelen, int even_cows) |
| 3013 | { |
| 3014 | struct zap_details details; |
| 3015 | pgoff_t hba = holebegin >> PAGE_SHIFT; |
| 3016 | pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 3017 | |
| 3018 | /* Check for overflow. */ |
| 3019 | if (sizeof(holelen) > sizeof(hlen)) { |
| 3020 | long long holeend = |
| 3021 | (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 3022 | if (holeend & ~(long long)ULONG_MAX) |
| 3023 | hlen = ULONG_MAX - hba + 1; |
| 3024 | } |
| 3025 | |
| 3026 | details.check_mapping = even_cows? NULL: mapping; |
| 3027 | details.nonlinear_vma = NULL; |
| 3028 | details.first_index = hba; |
| 3029 | details.last_index = hba + hlen - 1; |
| 3030 | if (details.last_index < details.first_index) |
| 3031 | details.last_index = ULONG_MAX; |
| 3032 | |
| 3033 | |
| 3034 | mutex_lock(&mapping->i_mmap_mutex); |
| 3035 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) |
| 3036 | unmap_mapping_range_tree(&mapping->i_mmap, &details); |
| 3037 | if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) |
| 3038 | unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); |
| 3039 | mutex_unlock(&mapping->i_mmap_mutex); |
| 3040 | } |
| 3041 | EXPORT_SYMBOL(unmap_mapping_range); |
| 3042 | |
| 3043 | /* |
| 3044 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| 3045 | * but allow concurrent faults), and pte mapped but not yet locked. |
| 3046 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
| 3047 | */ |
| 3048 | static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3049 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
| 3050 | unsigned int flags, pte_t orig_pte) |
| 3051 | { |
| 3052 | spinlock_t *ptl; |
| 3053 | struct page *page, *swapcache; |
| 3054 | swp_entry_t entry; |
| 3055 | pte_t pte; |
| 3056 | int locked; |
| 3057 | struct mem_cgroup *ptr; |
| 3058 | int exclusive = 0; |
| 3059 | int ret = 0; |
| 3060 | |
| 3061 | if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
| 3062 | goto out; |
| 3063 | |
| 3064 | entry = pte_to_swp_entry(orig_pte); |
| 3065 | if (unlikely(non_swap_entry(entry))) { |
| 3066 | if (is_migration_entry(entry)) { |
| 3067 | migration_entry_wait(mm, pmd, address); |
| 3068 | } else if (is_hwpoison_entry(entry)) { |
| 3069 | ret = VM_FAULT_HWPOISON; |
| 3070 | } else { |
| 3071 | print_bad_pte(vma, address, orig_pte, NULL); |
| 3072 | ret = VM_FAULT_SIGBUS; |
| 3073 | } |
| 3074 | goto out; |
| 3075 | } |
| 3076 | delayacct_set_flag(DELAYACCT_PF_SWAPIN); |
| 3077 | page = lookup_swap_cache(entry); |
| 3078 | if (!page) { |
| 3079 | page = swapin_readahead(entry, |
| 3080 | GFP_HIGHUSER_MOVABLE, vma, address); |
| 3081 | if (!page) { |
| 3082 | /* |
| 3083 | * Back out if somebody else faulted in this pte |
| 3084 | * while we released the pte lock. |
| 3085 | */ |
| 3086 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3087 | if (likely(pte_same(*page_table, orig_pte))) |
| 3088 | ret = VM_FAULT_OOM; |
| 3089 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
| 3090 | goto unlock; |
| 3091 | } |
| 3092 | |
| 3093 | /* Had to read the page from swap area: Major fault */ |
| 3094 | ret = VM_FAULT_MAJOR; |
| 3095 | count_vm_event(PGMAJFAULT); |
| 3096 | mem_cgroup_count_vm_event(mm, PGMAJFAULT); |
| 3097 | } else if (PageHWPoison(page)) { |
| 3098 | /* |
| 3099 | * hwpoisoned dirty swapcache pages are kept for killing |
| 3100 | * owner processes (which may be unknown at hwpoison time) |
| 3101 | */ |
| 3102 | ret = VM_FAULT_HWPOISON; |
| 3103 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
| 3104 | swapcache = page; |
| 3105 | goto out_release; |
| 3106 | } |
| 3107 | |
| 3108 | swapcache = page; |
| 3109 | locked = lock_page_or_retry(page, mm, flags); |
| 3110 | |
| 3111 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
| 3112 | if (!locked) { |
| 3113 | ret |= VM_FAULT_RETRY; |
| 3114 | goto out_release; |
| 3115 | } |
| 3116 | |
| 3117 | /* |
| 3118 | * Make sure try_to_free_swap or reuse_swap_page or swapoff did not |
| 3119 | * release the swapcache from under us. The page pin, and pte_same |
| 3120 | * test below, are not enough to exclude that. Even if it is still |
| 3121 | * swapcache, we need to check that the page's swap has not changed. |
| 3122 | */ |
| 3123 | if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) |
| 3124 | goto out_page; |
| 3125 | |
| 3126 | page = ksm_might_need_to_copy(page, vma, address); |
| 3127 | if (unlikely(!page)) { |
| 3128 | ret = VM_FAULT_OOM; |
| 3129 | page = swapcache; |
| 3130 | goto out_page; |
| 3131 | } |
| 3132 | |
| 3133 | if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { |
| 3134 | ret = VM_FAULT_OOM; |
| 3135 | goto out_page; |
| 3136 | } |
| 3137 | |
| 3138 | /* |
| 3139 | * Back out if somebody else already faulted in this pte. |
| 3140 | */ |
| 3141 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3142 | if (unlikely(!pte_same(*page_table, orig_pte))) |
| 3143 | goto out_nomap; |
| 3144 | |
| 3145 | if (unlikely(!PageUptodate(page))) { |
| 3146 | ret = VM_FAULT_SIGBUS; |
| 3147 | goto out_nomap; |
| 3148 | } |
| 3149 | |
| 3150 | /* |
| 3151 | * The page isn't present yet, go ahead with the fault. |
| 3152 | * |
| 3153 | * Be careful about the sequence of operations here. |
| 3154 | * To get its accounting right, reuse_swap_page() must be called |
| 3155 | * while the page is counted on swap but not yet in mapcount i.e. |
| 3156 | * before page_add_anon_rmap() and swap_free(); try_to_free_swap() |
| 3157 | * must be called after the swap_free(), or it will never succeed. |
| 3158 | * Because delete_from_swap_page() may be called by reuse_swap_page(), |
| 3159 | * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry |
| 3160 | * in page->private. In this case, a record in swap_cgroup is silently |
| 3161 | * discarded at swap_free(). |
| 3162 | */ |
| 3163 | |
| 3164 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
| 3165 | dec_mm_counter_fast(mm, MM_SWAPENTS); |
| 3166 | pte = mk_pte(page, vma->vm_page_prot); |
| 3167 | if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { |
| 3168 | pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
| 3169 | flags &= ~FAULT_FLAG_WRITE; |
| 3170 | ret |= VM_FAULT_WRITE; |
| 3171 | exclusive = 1; |
| 3172 | } |
| 3173 | flush_icache_page(vma, page); |
| 3174 | if (pte_swp_soft_dirty(orig_pte)) |
| 3175 | pte = pte_mksoft_dirty(pte); |
| 3176 | set_pte_at(mm, address, page_table, pte); |
| 3177 | if (page == swapcache) |
| 3178 | do_page_add_anon_rmap(page, vma, address, exclusive); |
| 3179 | else /* ksm created a completely new copy */ |
| 3180 | page_add_new_anon_rmap(page, vma, address); |
| 3181 | /* It's better to call commit-charge after rmap is established */ |
| 3182 | mem_cgroup_commit_charge_swapin(page, ptr); |
| 3183 | |
| 3184 | swap_free(entry); |
| 3185 | if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) |
| 3186 | try_to_free_swap(page); |
| 3187 | unlock_page(page); |
| 3188 | if (page != swapcache) { |
| 3189 | /* |
| 3190 | * Hold the lock to avoid the swap entry to be reused |
| 3191 | * until we take the PT lock for the pte_same() check |
| 3192 | * (to avoid false positives from pte_same). For |
| 3193 | * further safety release the lock after the swap_free |
| 3194 | * so that the swap count won't change under a |
| 3195 | * parallel locked swapcache. |
| 3196 | */ |
| 3197 | unlock_page(swapcache); |
| 3198 | page_cache_release(swapcache); |
| 3199 | } |
| 3200 | |
| 3201 | if (flags & FAULT_FLAG_WRITE) { |
| 3202 | ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); |
| 3203 | if (ret & VM_FAULT_ERROR) |
| 3204 | ret &= VM_FAULT_ERROR; |
| 3205 | goto out; |
| 3206 | } |
| 3207 | |
| 3208 | /* No need to invalidate - it was non-present before */ |
| 3209 | update_mmu_cache(vma, address, page_table); |
| 3210 | unlock: |
| 3211 | pte_unmap_unlock(page_table, ptl); |
| 3212 | out: |
| 3213 | return ret; |
| 3214 | out_nomap: |
| 3215 | mem_cgroup_cancel_charge_swapin(ptr); |
| 3216 | pte_unmap_unlock(page_table, ptl); |
| 3217 | out_page: |
| 3218 | unlock_page(page); |
| 3219 | out_release: |
| 3220 | page_cache_release(page); |
| 3221 | if (page != swapcache) { |
| 3222 | unlock_page(swapcache); |
| 3223 | page_cache_release(swapcache); |
| 3224 | } |
| 3225 | return ret; |
| 3226 | } |
| 3227 | |
| 3228 | /* |
| 3229 | * This is like a special single-page "expand_{down|up}wards()", |
| 3230 | * except we must first make sure that 'address{-|+}PAGE_SIZE' |
| 3231 | * doesn't hit another vma. |
| 3232 | */ |
| 3233 | static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) |
| 3234 | { |
| 3235 | address &= PAGE_MASK; |
| 3236 | if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { |
| 3237 | struct vm_area_struct *prev = vma->vm_prev; |
| 3238 | |
| 3239 | /* |
| 3240 | * Is there a mapping abutting this one below? |
| 3241 | * |
| 3242 | * That's only ok if it's the same stack mapping |
| 3243 | * that has gotten split.. |
| 3244 | */ |
| 3245 | if (prev && prev->vm_end == address) |
| 3246 | return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; |
| 3247 | |
| 3248 | expand_downwards(vma, address - PAGE_SIZE); |
| 3249 | } |
| 3250 | if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { |
| 3251 | struct vm_area_struct *next = vma->vm_next; |
| 3252 | |
| 3253 | /* As VM_GROWSDOWN but s/below/above/ */ |
| 3254 | if (next && next->vm_start == address + PAGE_SIZE) |
| 3255 | return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; |
| 3256 | |
| 3257 | expand_upwards(vma, address + PAGE_SIZE); |
| 3258 | } |
| 3259 | return 0; |
| 3260 | } |
| 3261 | |
| 3262 | /* |
| 3263 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| 3264 | * but allow concurrent faults), and pte mapped but not yet locked. |
| 3265 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
| 3266 | */ |
| 3267 | static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3268 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
| 3269 | unsigned int flags) |
| 3270 | { |
| 3271 | struct page *page; |
| 3272 | spinlock_t *ptl; |
| 3273 | pte_t entry; |
| 3274 | |
| 3275 | pte_unmap(page_table); |
| 3276 | |
| 3277 | /* Check if we need to add a guard page to the stack */ |
| 3278 | if (check_stack_guard_page(vma, address) < 0) |
| 3279 | return VM_FAULT_SIGBUS; |
| 3280 | |
| 3281 | /* Use the zero-page for reads */ |
| 3282 | if (!(flags & FAULT_FLAG_WRITE)) { |
| 3283 | entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), |
| 3284 | vma->vm_page_prot)); |
| 3285 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3286 | if (!pte_none(*page_table)) |
| 3287 | goto unlock; |
| 3288 | goto setpte; |
| 3289 | } |
| 3290 | |
| 3291 | /* Allocate our own private page. */ |
| 3292 | if (unlikely(anon_vma_prepare(vma))) |
| 3293 | goto oom; |
| 3294 | page = alloc_zeroed_user_highpage_movable(vma, address); |
| 3295 | if (!page) |
| 3296 | goto oom; |
| 3297 | /* |
| 3298 | * The memory barrier inside __SetPageUptodate makes sure that |
| 3299 | * preceeding stores to the page contents become visible before |
| 3300 | * the set_pte_at() write. |
| 3301 | */ |
| 3302 | __SetPageUptodate(page); |
| 3303 | |
| 3304 | if (mem_cgroup_charge_anon(page, mm, GFP_KERNEL)) |
| 3305 | goto oom_free_page; |
| 3306 | |
| 3307 | entry = mk_pte(page, vma->vm_page_prot); |
| 3308 | if (vma->vm_flags & VM_WRITE) |
| 3309 | entry = pte_mkwrite(pte_mkdirty(entry)); |
| 3310 | |
| 3311 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3312 | if (!pte_none(*page_table)) |
| 3313 | goto release; |
| 3314 | |
| 3315 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
| 3316 | page_add_new_anon_rmap(page, vma, address); |
| 3317 | setpte: |
| 3318 | set_pte_at(mm, address, page_table, entry); |
| 3319 | |
| 3320 | /* No need to invalidate - it was non-present before */ |
| 3321 | update_mmu_cache(vma, address, page_table); |
| 3322 | unlock: |
| 3323 | pte_unmap_unlock(page_table, ptl); |
| 3324 | return 0; |
| 3325 | release: |
| 3326 | mem_cgroup_uncharge_page(page); |
| 3327 | page_cache_release(page); |
| 3328 | goto unlock; |
| 3329 | oom_free_page: |
| 3330 | page_cache_release(page); |
| 3331 | oom: |
| 3332 | return VM_FAULT_OOM; |
| 3333 | } |
| 3334 | |
| 3335 | static int __do_fault(struct vm_area_struct *vma, unsigned long address, |
| 3336 | pgoff_t pgoff, unsigned int flags, struct page **page) |
| 3337 | { |
| 3338 | struct vm_fault vmf; |
| 3339 | int ret; |
| 3340 | |
| 3341 | vmf.virtual_address = (void __user *)(address & PAGE_MASK); |
| 3342 | vmf.pgoff = pgoff; |
| 3343 | vmf.flags = flags; |
| 3344 | vmf.page = NULL; |
| 3345 | |
| 3346 | ret = vma->vm_ops->fault(vma, &vmf); |
| 3347 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| 3348 | return ret; |
| 3349 | |
| 3350 | if (unlikely(PageHWPoison(vmf.page))) { |
| 3351 | if (ret & VM_FAULT_LOCKED) |
| 3352 | unlock_page(vmf.page); |
| 3353 | page_cache_release(vmf.page); |
| 3354 | return VM_FAULT_HWPOISON; |
| 3355 | } |
| 3356 | |
| 3357 | if (unlikely(!(ret & VM_FAULT_LOCKED))) |
| 3358 | lock_page(vmf.page); |
| 3359 | else |
| 3360 | VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page); |
| 3361 | |
| 3362 | *page = vmf.page; |
| 3363 | return ret; |
| 3364 | } |
| 3365 | |
| 3366 | /** |
| 3367 | * do_set_pte - setup new PTE entry for given page and add reverse page mapping. |
| 3368 | * |
| 3369 | * @vma: virtual memory area |
| 3370 | * @address: user virtual address |
| 3371 | * @page: page to map |
| 3372 | * @pte: pointer to target page table entry |
| 3373 | * @write: true, if new entry is writable |
| 3374 | * @anon: true, if it's anonymous page |
| 3375 | * |
| 3376 | * Caller must hold page table lock relevant for @pte. |
| 3377 | * |
| 3378 | * Target users are page handler itself and implementations of |
| 3379 | * vm_ops->map_pages. |
| 3380 | */ |
| 3381 | void do_set_pte(struct vm_area_struct *vma, unsigned long address, |
| 3382 | struct page *page, pte_t *pte, bool write, bool anon) |
| 3383 | { |
| 3384 | pte_t entry; |
| 3385 | |
| 3386 | flush_icache_page(vma, page); |
| 3387 | entry = mk_pte(page, vma->vm_page_prot); |
| 3388 | if (write) |
| 3389 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| 3390 | else if (pte_file(*pte) && pte_file_soft_dirty(*pte)) |
| 3391 | pte_mksoft_dirty(entry); |
| 3392 | if (anon) { |
| 3393 | inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); |
| 3394 | page_add_new_anon_rmap(page, vma, address); |
| 3395 | } else { |
| 3396 | inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES); |
| 3397 | page_add_file_rmap(page); |
| 3398 | } |
| 3399 | set_pte_at(vma->vm_mm, address, pte, entry); |
| 3400 | |
| 3401 | /* no need to invalidate: a not-present page won't be cached */ |
| 3402 | update_mmu_cache(vma, address, pte); |
| 3403 | } |
| 3404 | |
| 3405 | #define FAULT_AROUND_ORDER 4 |
| 3406 | |
| 3407 | #ifdef CONFIG_DEBUG_FS |
| 3408 | static unsigned int fault_around_order = FAULT_AROUND_ORDER; |
| 3409 | |
| 3410 | static int fault_around_order_get(void *data, u64 *val) |
| 3411 | { |
| 3412 | *val = fault_around_order; |
| 3413 | return 0; |
| 3414 | } |
| 3415 | |
| 3416 | static int fault_around_order_set(void *data, u64 val) |
| 3417 | { |
| 3418 | BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE); |
| 3419 | if (1UL << val > PTRS_PER_PTE) |
| 3420 | return -EINVAL; |
| 3421 | fault_around_order = val; |
| 3422 | return 0; |
| 3423 | } |
| 3424 | DEFINE_SIMPLE_ATTRIBUTE(fault_around_order_fops, |
| 3425 | fault_around_order_get, fault_around_order_set, "%llu\n"); |
| 3426 | |
| 3427 | static int __init fault_around_debugfs(void) |
| 3428 | { |
| 3429 | void *ret; |
| 3430 | |
| 3431 | ret = debugfs_create_file("fault_around_order", 0644, NULL, NULL, |
| 3432 | &fault_around_order_fops); |
| 3433 | if (!ret) |
| 3434 | pr_warn("Failed to create fault_around_order in debugfs"); |
| 3435 | return 0; |
| 3436 | } |
| 3437 | late_initcall(fault_around_debugfs); |
| 3438 | |
| 3439 | static inline unsigned long fault_around_pages(void) |
| 3440 | { |
| 3441 | return 1UL << fault_around_order; |
| 3442 | } |
| 3443 | |
| 3444 | static inline unsigned long fault_around_mask(void) |
| 3445 | { |
| 3446 | return ~((1UL << (PAGE_SHIFT + fault_around_order)) - 1); |
| 3447 | } |
| 3448 | #else |
| 3449 | static inline unsigned long fault_around_pages(void) |
| 3450 | { |
| 3451 | unsigned long nr_pages; |
| 3452 | |
| 3453 | nr_pages = 1UL << FAULT_AROUND_ORDER; |
| 3454 | BUILD_BUG_ON(nr_pages > PTRS_PER_PTE); |
| 3455 | return nr_pages; |
| 3456 | } |
| 3457 | |
| 3458 | static inline unsigned long fault_around_mask(void) |
| 3459 | { |
| 3460 | return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1); |
| 3461 | } |
| 3462 | #endif |
| 3463 | |
| 3464 | static void do_fault_around(struct vm_area_struct *vma, unsigned long address, |
| 3465 | pte_t *pte, pgoff_t pgoff, unsigned int flags) |
| 3466 | { |
| 3467 | unsigned long start_addr; |
| 3468 | pgoff_t max_pgoff; |
| 3469 | struct vm_fault vmf; |
| 3470 | int off; |
| 3471 | |
| 3472 | start_addr = max(address & fault_around_mask(), vma->vm_start); |
| 3473 | off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); |
| 3474 | pte -= off; |
| 3475 | pgoff -= off; |
| 3476 | |
| 3477 | /* |
| 3478 | * max_pgoff is either end of page table or end of vma |
| 3479 | * or fault_around_pages() from pgoff, depending what is neast. |
| 3480 | */ |
| 3481 | max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + |
| 3482 | PTRS_PER_PTE - 1; |
| 3483 | max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1, |
| 3484 | pgoff + fault_around_pages() - 1); |
| 3485 | |
| 3486 | /* Check if it makes any sense to call ->map_pages */ |
| 3487 | while (!pte_none(*pte)) { |
| 3488 | if (++pgoff > max_pgoff) |
| 3489 | return; |
| 3490 | start_addr += PAGE_SIZE; |
| 3491 | if (start_addr >= vma->vm_end) |
| 3492 | return; |
| 3493 | pte++; |
| 3494 | } |
| 3495 | |
| 3496 | vmf.virtual_address = (void __user *) start_addr; |
| 3497 | vmf.pte = pte; |
| 3498 | vmf.pgoff = pgoff; |
| 3499 | vmf.max_pgoff = max_pgoff; |
| 3500 | vmf.flags = flags; |
| 3501 | vma->vm_ops->map_pages(vma, &vmf); |
| 3502 | } |
| 3503 | |
| 3504 | static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3505 | unsigned long address, pmd_t *pmd, |
| 3506 | pgoff_t pgoff, unsigned int flags, pte_t orig_pte) |
| 3507 | { |
| 3508 | struct page *fault_page; |
| 3509 | spinlock_t *ptl; |
| 3510 | pte_t *pte; |
| 3511 | int ret = 0; |
| 3512 | |
| 3513 | /* |
| 3514 | * Let's call ->map_pages() first and use ->fault() as fallback |
| 3515 | * if page by the offset is not ready to be mapped (cold cache or |
| 3516 | * something). |
| 3517 | */ |
| 3518 | if (vma->vm_ops->map_pages) { |
| 3519 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3520 | do_fault_around(vma, address, pte, pgoff, flags); |
| 3521 | if (!pte_same(*pte, orig_pte)) |
| 3522 | goto unlock_out; |
| 3523 | pte_unmap_unlock(pte, ptl); |
| 3524 | } |
| 3525 | |
| 3526 | ret = __do_fault(vma, address, pgoff, flags, &fault_page); |
| 3527 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| 3528 | return ret; |
| 3529 | |
| 3530 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3531 | if (unlikely(!pte_same(*pte, orig_pte))) { |
| 3532 | pte_unmap_unlock(pte, ptl); |
| 3533 | unlock_page(fault_page); |
| 3534 | page_cache_release(fault_page); |
| 3535 | return ret; |
| 3536 | } |
| 3537 | do_set_pte(vma, address, fault_page, pte, false, false); |
| 3538 | unlock_page(fault_page); |
| 3539 | unlock_out: |
| 3540 | pte_unmap_unlock(pte, ptl); |
| 3541 | return ret; |
| 3542 | } |
| 3543 | |
| 3544 | static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3545 | unsigned long address, pmd_t *pmd, |
| 3546 | pgoff_t pgoff, unsigned int flags, pte_t orig_pte) |
| 3547 | { |
| 3548 | struct page *fault_page, *new_page; |
| 3549 | spinlock_t *ptl; |
| 3550 | pte_t *pte; |
| 3551 | int ret; |
| 3552 | |
| 3553 | if (unlikely(anon_vma_prepare(vma))) |
| 3554 | return VM_FAULT_OOM; |
| 3555 | |
| 3556 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
| 3557 | if (!new_page) |
| 3558 | return VM_FAULT_OOM; |
| 3559 | |
| 3560 | if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) { |
| 3561 | page_cache_release(new_page); |
| 3562 | return VM_FAULT_OOM; |
| 3563 | } |
| 3564 | |
| 3565 | ret = __do_fault(vma, address, pgoff, flags, &fault_page); |
| 3566 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| 3567 | goto uncharge_out; |
| 3568 | |
| 3569 | copy_user_highpage(new_page, fault_page, address, vma); |
| 3570 | __SetPageUptodate(new_page); |
| 3571 | |
| 3572 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3573 | if (unlikely(!pte_same(*pte, orig_pte))) { |
| 3574 | pte_unmap_unlock(pte, ptl); |
| 3575 | unlock_page(fault_page); |
| 3576 | page_cache_release(fault_page); |
| 3577 | goto uncharge_out; |
| 3578 | } |
| 3579 | do_set_pte(vma, address, new_page, pte, true, true); |
| 3580 | pte_unmap_unlock(pte, ptl); |
| 3581 | unlock_page(fault_page); |
| 3582 | page_cache_release(fault_page); |
| 3583 | return ret; |
| 3584 | uncharge_out: |
| 3585 | mem_cgroup_uncharge_page(new_page); |
| 3586 | page_cache_release(new_page); |
| 3587 | return ret; |
| 3588 | } |
| 3589 | |
| 3590 | static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3591 | unsigned long address, pmd_t *pmd, |
| 3592 | pgoff_t pgoff, unsigned int flags, pte_t orig_pte) |
| 3593 | { |
| 3594 | struct page *fault_page; |
| 3595 | struct address_space *mapping; |
| 3596 | spinlock_t *ptl; |
| 3597 | pte_t *pte; |
| 3598 | int dirtied = 0; |
| 3599 | int ret, tmp; |
| 3600 | |
| 3601 | ret = __do_fault(vma, address, pgoff, flags, &fault_page); |
| 3602 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| 3603 | return ret; |
| 3604 | |
| 3605 | /* |
| 3606 | * Check if the backing address space wants to know that the page is |
| 3607 | * about to become writable |
| 3608 | */ |
| 3609 | if (vma->vm_ops->page_mkwrite) { |
| 3610 | unlock_page(fault_page); |
| 3611 | tmp = do_page_mkwrite(vma, fault_page, address); |
| 3612 | if (unlikely(!tmp || |
| 3613 | (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
| 3614 | page_cache_release(fault_page); |
| 3615 | return tmp; |
| 3616 | } |
| 3617 | } |
| 3618 | |
| 3619 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
| 3620 | if (unlikely(!pte_same(*pte, orig_pte))) { |
| 3621 | pte_unmap_unlock(pte, ptl); |
| 3622 | unlock_page(fault_page); |
| 3623 | page_cache_release(fault_page); |
| 3624 | return ret; |
| 3625 | } |
| 3626 | do_set_pte(vma, address, fault_page, pte, true, false); |
| 3627 | pte_unmap_unlock(pte, ptl); |
| 3628 | |
| 3629 | if (set_page_dirty(fault_page)) |
| 3630 | dirtied = 1; |
| 3631 | mapping = fault_page->mapping; |
| 3632 | unlock_page(fault_page); |
| 3633 | if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { |
| 3634 | /* |
| 3635 | * Some device drivers do not set page.mapping but still |
| 3636 | * dirty their pages |
| 3637 | */ |
| 3638 | balance_dirty_pages_ratelimited(mapping); |
| 3639 | } |
| 3640 | |
| 3641 | /* file_update_time outside page_lock */ |
| 3642 | if (vma->vm_file && !vma->vm_ops->page_mkwrite) |
| 3643 | file_update_time(vma->vm_file); |
| 3644 | |
| 3645 | return ret; |
| 3646 | } |
| 3647 | |
| 3648 | static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3649 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
| 3650 | unsigned int flags, pte_t orig_pte) |
| 3651 | { |
| 3652 | pgoff_t pgoff = (((address & PAGE_MASK) |
| 3653 | - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| 3654 | |
| 3655 | pte_unmap(page_table); |
| 3656 | if (!(flags & FAULT_FLAG_WRITE)) |
| 3657 | return do_read_fault(mm, vma, address, pmd, pgoff, flags, |
| 3658 | orig_pte); |
| 3659 | if (!(vma->vm_flags & VM_SHARED)) |
| 3660 | return do_cow_fault(mm, vma, address, pmd, pgoff, flags, |
| 3661 | orig_pte); |
| 3662 | return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
| 3663 | } |
| 3664 | |
| 3665 | /* |
| 3666 | * Fault of a previously existing named mapping. Repopulate the pte |
| 3667 | * from the encoded file_pte if possible. This enables swappable |
| 3668 | * nonlinear vmas. |
| 3669 | * |
| 3670 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| 3671 | * but allow concurrent faults), and pte mapped but not yet locked. |
| 3672 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
| 3673 | */ |
| 3674 | static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3675 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
| 3676 | unsigned int flags, pte_t orig_pte) |
| 3677 | { |
| 3678 | pgoff_t pgoff; |
| 3679 | |
| 3680 | flags |= FAULT_FLAG_NONLINEAR; |
| 3681 | |
| 3682 | if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
| 3683 | return 0; |
| 3684 | |
| 3685 | if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { |
| 3686 | /* |
| 3687 | * Page table corrupted: show pte and kill process. |
| 3688 | */ |
| 3689 | print_bad_pte(vma, address, orig_pte, NULL); |
| 3690 | return VM_FAULT_SIGBUS; |
| 3691 | } |
| 3692 | |
| 3693 | pgoff = pte_to_pgoff(orig_pte); |
| 3694 | if (!(flags & FAULT_FLAG_WRITE)) |
| 3695 | return do_read_fault(mm, vma, address, pmd, pgoff, flags, |
| 3696 | orig_pte); |
| 3697 | if (!(vma->vm_flags & VM_SHARED)) |
| 3698 | return do_cow_fault(mm, vma, address, pmd, pgoff, flags, |
| 3699 | orig_pte); |
| 3700 | return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
| 3701 | } |
| 3702 | |
| 3703 | static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, |
| 3704 | unsigned long addr, int page_nid, |
| 3705 | int *flags) |
| 3706 | { |
| 3707 | get_page(page); |
| 3708 | |
| 3709 | count_vm_numa_event(NUMA_HINT_FAULTS); |
| 3710 | if (page_nid == numa_node_id()) { |
| 3711 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
| 3712 | *flags |= TNF_FAULT_LOCAL; |
| 3713 | } |
| 3714 | |
| 3715 | return mpol_misplaced(page, vma, addr); |
| 3716 | } |
| 3717 | |
| 3718 | static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3719 | unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) |
| 3720 | { |
| 3721 | struct page *page = NULL; |
| 3722 | spinlock_t *ptl; |
| 3723 | int page_nid = -1; |
| 3724 | int last_cpupid; |
| 3725 | int target_nid; |
| 3726 | bool migrated = false; |
| 3727 | int flags = 0; |
| 3728 | |
| 3729 | /* |
| 3730 | * The "pte" at this point cannot be used safely without |
| 3731 | * validation through pte_unmap_same(). It's of NUMA type but |
| 3732 | * the pfn may be screwed if the read is non atomic. |
| 3733 | * |
| 3734 | * ptep_modify_prot_start is not called as this is clearing |
| 3735 | * the _PAGE_NUMA bit and it is not really expected that there |
| 3736 | * would be concurrent hardware modifications to the PTE. |
| 3737 | */ |
| 3738 | ptl = pte_lockptr(mm, pmd); |
| 3739 | spin_lock(ptl); |
| 3740 | if (unlikely(!pte_same(*ptep, pte))) { |
| 3741 | pte_unmap_unlock(ptep, ptl); |
| 3742 | goto out; |
| 3743 | } |
| 3744 | |
| 3745 | pte = pte_mknonnuma(pte); |
| 3746 | set_pte_at(mm, addr, ptep, pte); |
| 3747 | update_mmu_cache(vma, addr, ptep); |
| 3748 | |
| 3749 | page = vm_normal_page(vma, addr, pte); |
| 3750 | if (!page) { |
| 3751 | pte_unmap_unlock(ptep, ptl); |
| 3752 | return 0; |
| 3753 | } |
| 3754 | BUG_ON(is_zero_pfn(page_to_pfn(page))); |
| 3755 | |
| 3756 | /* |
| 3757 | * Avoid grouping on DSO/COW pages in specific and RO pages |
| 3758 | * in general, RO pages shouldn't hurt as much anyway since |
| 3759 | * they can be in shared cache state. |
| 3760 | */ |
| 3761 | if (!pte_write(pte)) |
| 3762 | flags |= TNF_NO_GROUP; |
| 3763 | |
| 3764 | /* |
| 3765 | * Flag if the page is shared between multiple address spaces. This |
| 3766 | * is later used when determining whether to group tasks together |
| 3767 | */ |
| 3768 | if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) |
| 3769 | flags |= TNF_SHARED; |
| 3770 | |
| 3771 | last_cpupid = page_cpupid_last(page); |
| 3772 | page_nid = page_to_nid(page); |
| 3773 | target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags); |
| 3774 | pte_unmap_unlock(ptep, ptl); |
| 3775 | if (target_nid == -1) { |
| 3776 | put_page(page); |
| 3777 | goto out; |
| 3778 | } |
| 3779 | |
| 3780 | /* Migrate to the requested node */ |
| 3781 | migrated = migrate_misplaced_page(page, vma, target_nid); |
| 3782 | if (migrated) { |
| 3783 | page_nid = target_nid; |
| 3784 | flags |= TNF_MIGRATED; |
| 3785 | } |
| 3786 | |
| 3787 | out: |
| 3788 | if (page_nid != -1) |
| 3789 | task_numa_fault(last_cpupid, page_nid, 1, flags); |
| 3790 | return 0; |
| 3791 | } |
| 3792 | |
| 3793 | /* |
| 3794 | * These routines also need to handle stuff like marking pages dirty |
| 3795 | * and/or accessed for architectures that don't do it in hardware (most |
| 3796 | * RISC architectures). The early dirtying is also good on the i386. |
| 3797 | * |
| 3798 | * There is also a hook called "update_mmu_cache()" that architectures |
| 3799 | * with external mmu caches can use to update those (ie the Sparc or |
| 3800 | * PowerPC hashed page tables that act as extended TLBs). |
| 3801 | * |
| 3802 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| 3803 | * but allow concurrent faults), and pte mapped but not yet locked. |
| 3804 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
| 3805 | */ |
| 3806 | static int handle_pte_fault(struct mm_struct *mm, |
| 3807 | struct vm_area_struct *vma, unsigned long address, |
| 3808 | pte_t *pte, pmd_t *pmd, unsigned int flags) |
| 3809 | { |
| 3810 | pte_t entry; |
| 3811 | spinlock_t *ptl; |
| 3812 | |
| 3813 | entry = *pte; |
| 3814 | if (!pte_present(entry)) { |
| 3815 | if (pte_none(entry)) { |
| 3816 | if (vma->vm_ops) { |
| 3817 | if (likely(vma->vm_ops->fault)) |
| 3818 | return do_linear_fault(mm, vma, address, |
| 3819 | pte, pmd, flags, entry); |
| 3820 | } |
| 3821 | return do_anonymous_page(mm, vma, address, |
| 3822 | pte, pmd, flags); |
| 3823 | } |
| 3824 | if (pte_file(entry)) |
| 3825 | return do_nonlinear_fault(mm, vma, address, |
| 3826 | pte, pmd, flags, entry); |
| 3827 | return do_swap_page(mm, vma, address, |
| 3828 | pte, pmd, flags, entry); |
| 3829 | } |
| 3830 | |
| 3831 | if (pte_numa(entry)) |
| 3832 | return do_numa_page(mm, vma, address, entry, pte, pmd); |
| 3833 | |
| 3834 | ptl = pte_lockptr(mm, pmd); |
| 3835 | spin_lock(ptl); |
| 3836 | if (unlikely(!pte_same(*pte, entry))) |
| 3837 | goto unlock; |
| 3838 | if (flags & FAULT_FLAG_WRITE) { |
| 3839 | if (!pte_write(entry)) |
| 3840 | return do_wp_page(mm, vma, address, |
| 3841 | pte, pmd, ptl, entry); |
| 3842 | entry = pte_mkdirty(entry); |
| 3843 | } |
| 3844 | entry = pte_mkyoung(entry); |
| 3845 | if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { |
| 3846 | update_mmu_cache(vma, address, pte); |
| 3847 | } else { |
| 3848 | /* |
| 3849 | * This is needed only for protection faults but the arch code |
| 3850 | * is not yet telling us if this is a protection fault or not. |
| 3851 | * This still avoids useless tlb flushes for .text page faults |
| 3852 | * with threads. |
| 3853 | */ |
| 3854 | if (flags & FAULT_FLAG_WRITE) |
| 3855 | flush_tlb_fix_spurious_fault(vma, address); |
| 3856 | } |
| 3857 | unlock: |
| 3858 | pte_unmap_unlock(pte, ptl); |
| 3859 | return 0; |
| 3860 | } |
| 3861 | |
| 3862 | /* |
| 3863 | * By the time we get here, we already hold the mm semaphore |
| 3864 | */ |
| 3865 | static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3866 | unsigned long address, unsigned int flags) |
| 3867 | { |
| 3868 | pgd_t *pgd; |
| 3869 | pud_t *pud; |
| 3870 | pmd_t *pmd; |
| 3871 | pte_t *pte; |
| 3872 | |
| 3873 | if (unlikely(is_vm_hugetlb_page(vma))) |
| 3874 | return hugetlb_fault(mm, vma, address, flags); |
| 3875 | |
| 3876 | pgd = pgd_offset(mm, address); |
| 3877 | pud = pud_alloc(mm, pgd, address); |
| 3878 | if (!pud) |
| 3879 | return VM_FAULT_OOM; |
| 3880 | pmd = pmd_alloc(mm, pud, address); |
| 3881 | if (!pmd) |
| 3882 | return VM_FAULT_OOM; |
| 3883 | if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { |
| 3884 | int ret = VM_FAULT_FALLBACK; |
| 3885 | if (!vma->vm_ops) |
| 3886 | ret = do_huge_pmd_anonymous_page(mm, vma, address, |
| 3887 | pmd, flags); |
| 3888 | if (!(ret & VM_FAULT_FALLBACK)) |
| 3889 | return ret; |
| 3890 | } else { |
| 3891 | pmd_t orig_pmd = *pmd; |
| 3892 | int ret; |
| 3893 | |
| 3894 | barrier(); |
| 3895 | if (pmd_trans_huge(orig_pmd)) { |
| 3896 | unsigned int dirty = flags & FAULT_FLAG_WRITE; |
| 3897 | |
| 3898 | /* |
| 3899 | * If the pmd is splitting, return and retry the |
| 3900 | * the fault. Alternative: wait until the split |
| 3901 | * is done, and goto retry. |
| 3902 | */ |
| 3903 | if (pmd_trans_splitting(orig_pmd)) |
| 3904 | return 0; |
| 3905 | |
| 3906 | if (pmd_numa(orig_pmd)) |
| 3907 | return do_huge_pmd_numa_page(mm, vma, address, |
| 3908 | orig_pmd, pmd); |
| 3909 | |
| 3910 | if (dirty && !pmd_write(orig_pmd)) { |
| 3911 | ret = do_huge_pmd_wp_page(mm, vma, address, pmd, |
| 3912 | orig_pmd); |
| 3913 | if (!(ret & VM_FAULT_FALLBACK)) |
| 3914 | return ret; |
| 3915 | } else { |
| 3916 | huge_pmd_set_accessed(mm, vma, address, pmd, |
| 3917 | orig_pmd, dirty); |
| 3918 | return 0; |
| 3919 | } |
| 3920 | } |
| 3921 | } |
| 3922 | |
| 3923 | /* THP should already have been handled */ |
| 3924 | BUG_ON(pmd_numa(*pmd)); |
| 3925 | |
| 3926 | /* |
| 3927 | * Use __pte_alloc instead of pte_alloc_map, because we can't |
| 3928 | * run pte_offset_map on the pmd, if an huge pmd could |
| 3929 | * materialize from under us from a different thread. |
| 3930 | */ |
| 3931 | if (unlikely(pmd_none(*pmd)) && |
| 3932 | unlikely(__pte_alloc(mm, vma, pmd, address))) |
| 3933 | return VM_FAULT_OOM; |
| 3934 | /* if an huge pmd materialized from under us just retry later */ |
| 3935 | if (unlikely(pmd_trans_huge(*pmd))) |
| 3936 | return 0; |
| 3937 | /* |
| 3938 | * A regular pmd is established and it can't morph into a huge pmd |
| 3939 | * from under us anymore at this point because we hold the mmap_sem |
| 3940 | * read mode and khugepaged takes it in write mode. So now it's |
| 3941 | * safe to run pte_offset_map(). |
| 3942 | */ |
| 3943 | pte = pte_offset_map(pmd, address); |
| 3944 | |
| 3945 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); |
| 3946 | } |
| 3947 | |
| 3948 | int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 3949 | unsigned long address, unsigned int flags) |
| 3950 | { |
| 3951 | int ret; |
| 3952 | |
| 3953 | __set_current_state(TASK_RUNNING); |
| 3954 | |
| 3955 | count_vm_event(PGFAULT); |
| 3956 | mem_cgroup_count_vm_event(mm, PGFAULT); |
| 3957 | |
| 3958 | /* do counter updates before entering really critical section. */ |
| 3959 | check_sync_rss_stat(current); |
| 3960 | |
| 3961 | /* |
| 3962 | * Enable the memcg OOM handling for faults triggered in user |
| 3963 | * space. Kernel faults are handled more gracefully. |
| 3964 | */ |
| 3965 | if (flags & FAULT_FLAG_USER) |
| 3966 | mem_cgroup_oom_enable(); |
| 3967 | |
| 3968 | ret = __handle_mm_fault(mm, vma, address, flags); |
| 3969 | |
| 3970 | if (flags & FAULT_FLAG_USER) { |
| 3971 | mem_cgroup_oom_disable(); |
| 3972 | /* |
| 3973 | * The task may have entered a memcg OOM situation but |
| 3974 | * if the allocation error was handled gracefully (no |
| 3975 | * VM_FAULT_OOM), there is no need to kill anything. |
| 3976 | * Just clean up the OOM state peacefully. |
| 3977 | */ |
| 3978 | if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) |
| 3979 | mem_cgroup_oom_synchronize(false); |
| 3980 | } |
| 3981 | |
| 3982 | return ret; |
| 3983 | } |
| 3984 | |
| 3985 | #ifndef __PAGETABLE_PUD_FOLDED |
| 3986 | /* |
| 3987 | * Allocate page upper directory. |
| 3988 | * We've already handled the fast-path in-line. |
| 3989 | */ |
| 3990 | int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
| 3991 | { |
| 3992 | pud_t *new = pud_alloc_one(mm, address); |
| 3993 | if (!new) |
| 3994 | return -ENOMEM; |
| 3995 | |
| 3996 | smp_wmb(); /* See comment in __pte_alloc */ |
| 3997 | |
| 3998 | spin_lock(&mm->page_table_lock); |
| 3999 | if (pgd_present(*pgd)) /* Another has populated it */ |
| 4000 | pud_free(mm, new); |
| 4001 | else |
| 4002 | pgd_populate(mm, pgd, new); |
| 4003 | spin_unlock(&mm->page_table_lock); |
| 4004 | return 0; |
| 4005 | } |
| 4006 | #endif /* __PAGETABLE_PUD_FOLDED */ |
| 4007 | |
| 4008 | #ifndef __PAGETABLE_PMD_FOLDED |
| 4009 | /* |
| 4010 | * Allocate page middle directory. |
| 4011 | * We've already handled the fast-path in-line. |
| 4012 | */ |
| 4013 | int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
| 4014 | { |
| 4015 | pmd_t *new = pmd_alloc_one(mm, address); |
| 4016 | if (!new) |
| 4017 | return -ENOMEM; |
| 4018 | |
| 4019 | smp_wmb(); /* See comment in __pte_alloc */ |
| 4020 | |
| 4021 | spin_lock(&mm->page_table_lock); |
| 4022 | #ifndef __ARCH_HAS_4LEVEL_HACK |
| 4023 | if (pud_present(*pud)) /* Another has populated it */ |
| 4024 | pmd_free(mm, new); |
| 4025 | else |
| 4026 | pud_populate(mm, pud, new); |
| 4027 | #else |
| 4028 | if (pgd_present(*pud)) /* Another has populated it */ |
| 4029 | pmd_free(mm, new); |
| 4030 | else |
| 4031 | pgd_populate(mm, pud, new); |
| 4032 | #endif /* __ARCH_HAS_4LEVEL_HACK */ |
| 4033 | spin_unlock(&mm->page_table_lock); |
| 4034 | return 0; |
| 4035 | } |
| 4036 | #endif /* __PAGETABLE_PMD_FOLDED */ |
| 4037 | |
| 4038 | #if !defined(__HAVE_ARCH_GATE_AREA) |
| 4039 | |
| 4040 | #if defined(AT_SYSINFO_EHDR) |
| 4041 | static struct vm_area_struct gate_vma; |
| 4042 | |
| 4043 | static int __init gate_vma_init(void) |
| 4044 | { |
| 4045 | gate_vma.vm_mm = NULL; |
| 4046 | gate_vma.vm_start = FIXADDR_USER_START; |
| 4047 | gate_vma.vm_end = FIXADDR_USER_END; |
| 4048 | gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; |
| 4049 | gate_vma.vm_page_prot = __P101; |
| 4050 | |
| 4051 | return 0; |
| 4052 | } |
| 4053 | __initcall(gate_vma_init); |
| 4054 | #endif |
| 4055 | |
| 4056 | struct vm_area_struct *get_gate_vma(struct mm_struct *mm) |
| 4057 | { |
| 4058 | #ifdef AT_SYSINFO_EHDR |
| 4059 | return &gate_vma; |
| 4060 | #else |
| 4061 | return NULL; |
| 4062 | #endif |
| 4063 | } |
| 4064 | |
| 4065 | int in_gate_area_no_mm(unsigned long addr) |
| 4066 | { |
| 4067 | #ifdef AT_SYSINFO_EHDR |
| 4068 | if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) |
| 4069 | return 1; |
| 4070 | #endif |
| 4071 | return 0; |
| 4072 | } |
| 4073 | |
| 4074 | #endif /* __HAVE_ARCH_GATE_AREA */ |
| 4075 | |
| 4076 | static int __follow_pte(struct mm_struct *mm, unsigned long address, |
| 4077 | pte_t **ptepp, spinlock_t **ptlp) |
| 4078 | { |
| 4079 | pgd_t *pgd; |
| 4080 | pud_t *pud; |
| 4081 | pmd_t *pmd; |
| 4082 | pte_t *ptep; |
| 4083 | |
| 4084 | pgd = pgd_offset(mm, address); |
| 4085 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| 4086 | goto out; |
| 4087 | |
| 4088 | pud = pud_offset(pgd, address); |
| 4089 | if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
| 4090 | goto out; |
| 4091 | |
| 4092 | pmd = pmd_offset(pud, address); |
| 4093 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
| 4094 | if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
| 4095 | goto out; |
| 4096 | |
| 4097 | /* We cannot handle huge page PFN maps. Luckily they don't exist. */ |
| 4098 | if (pmd_huge(*pmd)) |
| 4099 | goto out; |
| 4100 | |
| 4101 | ptep = pte_offset_map_lock(mm, pmd, address, ptlp); |
| 4102 | if (!ptep) |
| 4103 | goto out; |
| 4104 | if (!pte_present(*ptep)) |
| 4105 | goto unlock; |
| 4106 | *ptepp = ptep; |
| 4107 | return 0; |
| 4108 | unlock: |
| 4109 | pte_unmap_unlock(ptep, *ptlp); |
| 4110 | out: |
| 4111 | return -EINVAL; |
| 4112 | } |
| 4113 | |
| 4114 | static inline int follow_pte(struct mm_struct *mm, unsigned long address, |
| 4115 | pte_t **ptepp, spinlock_t **ptlp) |
| 4116 | { |
| 4117 | int res; |
| 4118 | |
| 4119 | /* (void) is needed to make gcc happy */ |
| 4120 | (void) __cond_lock(*ptlp, |
| 4121 | !(res = __follow_pte(mm, address, ptepp, ptlp))); |
| 4122 | return res; |
| 4123 | } |
| 4124 | |
| 4125 | /** |
| 4126 | * follow_pfn - look up PFN at a user virtual address |
| 4127 | * @vma: memory mapping |
| 4128 | * @address: user virtual address |
| 4129 | * @pfn: location to store found PFN |
| 4130 | * |
| 4131 | * Only IO mappings and raw PFN mappings are allowed. |
| 4132 | * |
| 4133 | * Returns zero and the pfn at @pfn on success, -ve otherwise. |
| 4134 | */ |
| 4135 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
| 4136 | unsigned long *pfn) |
| 4137 | { |
| 4138 | int ret = -EINVAL; |
| 4139 | spinlock_t *ptl; |
| 4140 | pte_t *ptep; |
| 4141 | |
| 4142 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| 4143 | return ret; |
| 4144 | |
| 4145 | ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); |
| 4146 | if (ret) |
| 4147 | return ret; |
| 4148 | *pfn = pte_pfn(*ptep); |
| 4149 | pte_unmap_unlock(ptep, ptl); |
| 4150 | return 0; |
| 4151 | } |
| 4152 | EXPORT_SYMBOL(follow_pfn); |
| 4153 | |
| 4154 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
| 4155 | int follow_phys(struct vm_area_struct *vma, |
| 4156 | unsigned long address, unsigned int flags, |
| 4157 | unsigned long *prot, resource_size_t *phys) |
| 4158 | { |
| 4159 | int ret = -EINVAL; |
| 4160 | pte_t *ptep, pte; |
| 4161 | spinlock_t *ptl; |
| 4162 | |
| 4163 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| 4164 | goto out; |
| 4165 | |
| 4166 | if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) |
| 4167 | goto out; |
| 4168 | pte = *ptep; |
| 4169 | |
| 4170 | if ((flags & FOLL_WRITE) && !pte_write(pte)) |
| 4171 | goto unlock; |
| 4172 | |
| 4173 | *prot = pgprot_val(pte_pgprot(pte)); |
| 4174 | *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
| 4175 | |
| 4176 | ret = 0; |
| 4177 | unlock: |
| 4178 | pte_unmap_unlock(ptep, ptl); |
| 4179 | out: |
| 4180 | return ret; |
| 4181 | } |
| 4182 | |
| 4183 | int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, |
| 4184 | void *buf, int len, int write) |
| 4185 | { |
| 4186 | resource_size_t phys_addr; |
| 4187 | unsigned long prot = 0; |
| 4188 | void __iomem *maddr; |
| 4189 | int offset = addr & (PAGE_SIZE-1); |
| 4190 | |
| 4191 | if (follow_phys(vma, addr, write, &prot, &phys_addr)) |
| 4192 | return -EINVAL; |
| 4193 | |
| 4194 | maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); |
| 4195 | if (write) |
| 4196 | memcpy_toio(maddr + offset, buf, len); |
| 4197 | else |
| 4198 | memcpy_fromio(buf, maddr + offset, len); |
| 4199 | iounmap(maddr); |
| 4200 | |
| 4201 | return len; |
| 4202 | } |
| 4203 | EXPORT_SYMBOL_GPL(generic_access_phys); |
| 4204 | #endif |
| 4205 | |
| 4206 | /* |
| 4207 | * Access another process' address space as given in mm. If non-NULL, use the |
| 4208 | * given task for page fault accounting. |
| 4209 | */ |
| 4210 | static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, |
| 4211 | unsigned long addr, void *buf, int len, int write) |
| 4212 | { |
| 4213 | struct vm_area_struct *vma; |
| 4214 | void *old_buf = buf; |
| 4215 | |
| 4216 | down_read(&mm->mmap_sem); |
| 4217 | /* ignore errors, just check how much was successfully transferred */ |
| 4218 | while (len) { |
| 4219 | int bytes, ret, offset; |
| 4220 | void *maddr; |
| 4221 | struct page *page = NULL; |
| 4222 | |
| 4223 | ret = get_user_pages(tsk, mm, addr, 1, |
| 4224 | write, 1, &page, &vma); |
| 4225 | if (ret <= 0) { |
| 4226 | /* |
| 4227 | * Check if this is a VM_IO | VM_PFNMAP VMA, which |
| 4228 | * we can access using slightly different code. |
| 4229 | */ |
| 4230 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
| 4231 | vma = find_vma(mm, addr); |
| 4232 | if (!vma || vma->vm_start > addr) |
| 4233 | break; |
| 4234 | if (vma->vm_ops && vma->vm_ops->access) |
| 4235 | ret = vma->vm_ops->access(vma, addr, buf, |
| 4236 | len, write); |
| 4237 | if (ret <= 0) |
| 4238 | #endif |
| 4239 | break; |
| 4240 | bytes = ret; |
| 4241 | } else { |
| 4242 | bytes = len; |
| 4243 | offset = addr & (PAGE_SIZE-1); |
| 4244 | if (bytes > PAGE_SIZE-offset) |
| 4245 | bytes = PAGE_SIZE-offset; |
| 4246 | |
| 4247 | maddr = kmap(page); |
| 4248 | if (write) { |
| 4249 | copy_to_user_page(vma, page, addr, |
| 4250 | maddr + offset, buf, bytes); |
| 4251 | set_page_dirty_lock(page); |
| 4252 | } else { |
| 4253 | copy_from_user_page(vma, page, addr, |
| 4254 | buf, maddr + offset, bytes); |
| 4255 | } |
| 4256 | kunmap(page); |
| 4257 | page_cache_release(page); |
| 4258 | } |
| 4259 | len -= bytes; |
| 4260 | buf += bytes; |
| 4261 | addr += bytes; |
| 4262 | } |
| 4263 | up_read(&mm->mmap_sem); |
| 4264 | |
| 4265 | return buf - old_buf; |
| 4266 | } |
| 4267 | |
| 4268 | /** |
| 4269 | * access_remote_vm - access another process' address space |
| 4270 | * @mm: the mm_struct of the target address space |
| 4271 | * @addr: start address to access |
| 4272 | * @buf: source or destination buffer |
| 4273 | * @len: number of bytes to transfer |
| 4274 | * @write: whether the access is a write |
| 4275 | * |
| 4276 | * The caller must hold a reference on @mm. |
| 4277 | */ |
| 4278 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
| 4279 | void *buf, int len, int write) |
| 4280 | { |
| 4281 | return __access_remote_vm(NULL, mm, addr, buf, len, write); |
| 4282 | } |
| 4283 | |
| 4284 | /* |
| 4285 | * Access another process' address space. |
| 4286 | * Source/target buffer must be kernel space, |
| 4287 | * Do not walk the page table directly, use get_user_pages |
| 4288 | */ |
| 4289 | int access_process_vm(struct task_struct *tsk, unsigned long addr, |
| 4290 | void *buf, int len, int write) |
| 4291 | { |
| 4292 | struct mm_struct *mm; |
| 4293 | int ret; |
| 4294 | |
| 4295 | mm = get_task_mm(tsk); |
| 4296 | if (!mm) |
| 4297 | return 0; |
| 4298 | |
| 4299 | ret = __access_remote_vm(tsk, mm, addr, buf, len, write); |
| 4300 | mmput(mm); |
| 4301 | |
| 4302 | return ret; |
| 4303 | } |
| 4304 | |
| 4305 | /* |
| 4306 | * Print the name of a VMA. |
| 4307 | */ |
| 4308 | void print_vma_addr(char *prefix, unsigned long ip) |
| 4309 | { |
| 4310 | struct mm_struct *mm = current->mm; |
| 4311 | struct vm_area_struct *vma; |
| 4312 | |
| 4313 | /* |
| 4314 | * Do not print if we are in atomic |
| 4315 | * contexts (in exception stacks, etc.): |
| 4316 | */ |
| 4317 | if (preempt_count()) |
| 4318 | return; |
| 4319 | |
| 4320 | down_read(&mm->mmap_sem); |
| 4321 | vma = find_vma(mm, ip); |
| 4322 | if (vma && vma->vm_file) { |
| 4323 | struct file *f = vma->vm_file; |
| 4324 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
| 4325 | if (buf) { |
| 4326 | char *p; |
| 4327 | |
| 4328 | p = d_path(&f->f_path, buf, PAGE_SIZE); |
| 4329 | if (IS_ERR(p)) |
| 4330 | p = "?"; |
| 4331 | printk("%s%s[%lx+%lx]", prefix, kbasename(p), |
| 4332 | vma->vm_start, |
| 4333 | vma->vm_end - vma->vm_start); |
| 4334 | free_page((unsigned long)buf); |
| 4335 | } |
| 4336 | } |
| 4337 | up_read(&mm->mmap_sem); |
| 4338 | } |
| 4339 | |
| 4340 | #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
| 4341 | void might_fault(void) |
| 4342 | { |
| 4343 | /* |
| 4344 | * Some code (nfs/sunrpc) uses socket ops on kernel memory while |
| 4345 | * holding the mmap_sem, this is safe because kernel memory doesn't |
| 4346 | * get paged out, therefore we'll never actually fault, and the |
| 4347 | * below annotations will generate false positives. |
| 4348 | */ |
| 4349 | if (segment_eq(get_fs(), KERNEL_DS)) |
| 4350 | return; |
| 4351 | |
| 4352 | /* |
| 4353 | * it would be nicer only to annotate paths which are not under |
| 4354 | * pagefault_disable, however that requires a larger audit and |
| 4355 | * providing helpers like get_user_atomic. |
| 4356 | */ |
| 4357 | if (in_atomic()) |
| 4358 | return; |
| 4359 | |
| 4360 | __might_sleep(__FILE__, __LINE__, 0); |
| 4361 | |
| 4362 | if (current->mm) |
| 4363 | might_lock_read(¤t->mm->mmap_sem); |
| 4364 | } |
| 4365 | EXPORT_SYMBOL(might_fault); |
| 4366 | #endif |
| 4367 | |
| 4368 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) |
| 4369 | static void clear_gigantic_page(struct page *page, |
| 4370 | unsigned long addr, |
| 4371 | unsigned int pages_per_huge_page) |
| 4372 | { |
| 4373 | int i; |
| 4374 | struct page *p = page; |
| 4375 | |
| 4376 | might_sleep(); |
| 4377 | for (i = 0; i < pages_per_huge_page; |
| 4378 | i++, p = mem_map_next(p, page, i)) { |
| 4379 | cond_resched(); |
| 4380 | clear_user_highpage(p, addr + i * PAGE_SIZE); |
| 4381 | } |
| 4382 | } |
| 4383 | void clear_huge_page(struct page *page, |
| 4384 | unsigned long addr, unsigned int pages_per_huge_page) |
| 4385 | { |
| 4386 | int i; |
| 4387 | |
| 4388 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
| 4389 | clear_gigantic_page(page, addr, pages_per_huge_page); |
| 4390 | return; |
| 4391 | } |
| 4392 | |
| 4393 | might_sleep(); |
| 4394 | for (i = 0; i < pages_per_huge_page; i++) { |
| 4395 | cond_resched(); |
| 4396 | clear_user_highpage(page + i, addr + i * PAGE_SIZE); |
| 4397 | } |
| 4398 | } |
| 4399 | |
| 4400 | static void copy_user_gigantic_page(struct page *dst, struct page *src, |
| 4401 | unsigned long addr, |
| 4402 | struct vm_area_struct *vma, |
| 4403 | unsigned int pages_per_huge_page) |
| 4404 | { |
| 4405 | int i; |
| 4406 | struct page *dst_base = dst; |
| 4407 | struct page *src_base = src; |
| 4408 | |
| 4409 | for (i = 0; i < pages_per_huge_page; ) { |
| 4410 | cond_resched(); |
| 4411 | copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); |
| 4412 | |
| 4413 | i++; |
| 4414 | dst = mem_map_next(dst, dst_base, i); |
| 4415 | src = mem_map_next(src, src_base, i); |
| 4416 | } |
| 4417 | } |
| 4418 | |
| 4419 | void copy_user_huge_page(struct page *dst, struct page *src, |
| 4420 | unsigned long addr, struct vm_area_struct *vma, |
| 4421 | unsigned int pages_per_huge_page) |
| 4422 | { |
| 4423 | int i; |
| 4424 | |
| 4425 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
| 4426 | copy_user_gigantic_page(dst, src, addr, vma, |
| 4427 | pages_per_huge_page); |
| 4428 | return; |
| 4429 | } |
| 4430 | |
| 4431 | might_sleep(); |
| 4432 | for (i = 0; i < pages_per_huge_page; i++) { |
| 4433 | cond_resched(); |
| 4434 | copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); |
| 4435 | } |
| 4436 | } |
| 4437 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ |
| 4438 | |
| 4439 | #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS |
| 4440 | |
| 4441 | static struct kmem_cache *page_ptl_cachep; |
| 4442 | |
| 4443 | void __init ptlock_cache_init(void) |
| 4444 | { |
| 4445 | page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, |
| 4446 | SLAB_PANIC, NULL); |
| 4447 | } |
| 4448 | |
| 4449 | bool ptlock_alloc(struct page *page) |
| 4450 | { |
| 4451 | spinlock_t *ptl; |
| 4452 | |
| 4453 | ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); |
| 4454 | if (!ptl) |
| 4455 | return false; |
| 4456 | page->ptl = ptl; |
| 4457 | return true; |
| 4458 | } |
| 4459 | |
| 4460 | void ptlock_free(struct page *page) |
| 4461 | { |
| 4462 | kmem_cache_free(page_ptl_cachep, page->ptl); |
| 4463 | } |
| 4464 | #endif |