1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/mm/memory.c 4 * 5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 6 */ 7 8 /* 9 * demand-loading started 01.12.91 - seems it is high on the list of 10 * things wanted, and it should be easy to implement. - Linus 11 */ 12 13 /* 14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 15 * pages started 02.12.91, seems to work. - Linus. 16 * 17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 18 * would have taken more than the 6M I have free, but it worked well as 19 * far as I could see. 20 * 21 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 22 */ 23 24 /* 25 * Real VM (paging to/from disk) started 18.12.91. Much more work and 26 * thought has to go into this. Oh, well.. 27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 28 * Found it. Everything seems to work now. 29 * 20.12.91 - Ok, making the swap-device changeable like the root. 30 */ 31 32 /* 33 * 05.04.94 - Multi-page memory management added for v1.1. 34 * Idea by Alex Bligh (alex@cconcepts.co.uk) 35 * 36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 37 * (Gerhard.Wichert@pdb.siemens.de) 38 * 39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 40 */ 41 42 #include <linux/kernel_stat.h> 43 #include <linux/mm.h> 44 #include <linux/mm_inline.h> 45 #include <linux/sched/mm.h> 46 #include <linux/sched/coredump.h> 47 #include <linux/sched/numa_balancing.h> 48 #include <linux/sched/task.h> 49 #include <linux/hugetlb.h> 50 #include <linux/mman.h> 51 #include <linux/swap.h> 52 #include <linux/highmem.h> 53 #include <linux/pagemap.h> 54 #include <linux/memremap.h> 55 #include <linux/ksm.h> 56 #include <linux/rmap.h> 57 #include <linux/export.h> 58 #include <linux/delayacct.h> 59 #include <linux/init.h> 60 #include <linux/pfn_t.h> 61 #include <linux/writeback.h> 62 #include <linux/memcontrol.h> 63 #include <linux/mmu_notifier.h> 64 #include <linux/swapops.h> 65 #include <linux/elf.h> 66 #include <linux/gfp.h> 67 #include <linux/migrate.h> 68 #include <linux/string.h> 69 #include <linux/debugfs.h> 70 #include <linux/userfaultfd_k.h> 71 #include <linux/dax.h> 72 #include <linux/oom.h> 73 #include <linux/numa.h> 74 #include <linux/perf_event.h> 75 #include <linux/ptrace.h> 76 #include <linux/vmalloc.h> 77 78 #include <trace/events/kmem.h> 79 80 #include <asm/io.h> 81 #include <asm/mmu_context.h> 82 #include <asm/pgalloc.h> 83 #include <linux/uaccess.h> 84 #include <asm/tlb.h> 85 #include <asm/tlbflush.h> 86 87 #include "pgalloc-track.h" 88 #include "internal.h" 89 90 #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST) 91 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 92 #endif 93 94 #ifndef CONFIG_NUMA 95 unsigned long max_mapnr; 96 EXPORT_SYMBOL(max_mapnr); 97 98 struct page *mem_map; 99 EXPORT_SYMBOL(mem_map); 100 #endif 101 102 /* 103 * A number of key systems in x86 including ioremap() rely on the assumption 104 * that high_memory defines the upper bound on direct map memory, then end 105 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 106 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 107 * and ZONE_HIGHMEM. 108 */ 109 void *high_memory; 110 EXPORT_SYMBOL(high_memory); 111 112 /* 113 * Randomize the address space (stacks, mmaps, brk, etc.). 114 * 115 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 116 * as ancient (libc5 based) binaries can segfault. ) 117 */ 118 int randomize_va_space __read_mostly = 119 #ifdef CONFIG_COMPAT_BRK 120 1; 121 #else 122 2; 123 #endif 124 125 #ifndef arch_faults_on_old_pte 126 static inline bool arch_faults_on_old_pte(void) 127 { 128 /* 129 * Those arches which don't have hw access flag feature need to 130 * implement their own helper. By default, "true" means pagefault 131 * will be hit on old pte. 132 */ 133 return true; 134 } 135 #endif 136 137 #ifndef arch_wants_old_prefaulted_pte 138 static inline bool arch_wants_old_prefaulted_pte(void) 139 { 140 /* 141 * Transitioning a PTE from 'old' to 'young' can be expensive on 142 * some architectures, even if it's performed in hardware. By 143 * default, "false" means prefaulted entries will be 'young'. 144 */ 145 return false; 146 } 147 #endif 148 149 static int __init disable_randmaps(char *s) 150 { 151 randomize_va_space = 0; 152 return 1; 153 } 154 __setup("norandmaps", disable_randmaps); 155 156 unsigned long zero_pfn __read_mostly; 157 EXPORT_SYMBOL(zero_pfn); 158 159 unsigned long highest_memmap_pfn __read_mostly; 160 161 /* 162 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 163 */ 164 static int __init init_zero_pfn(void) 165 { 166 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 167 return 0; 168 } 169 early_initcall(init_zero_pfn); 170 171 void mm_trace_rss_stat(struct mm_struct *mm, int member, long count) 172 { 173 trace_rss_stat(mm, member, count); 174 } 175 176 #if defined(SPLIT_RSS_COUNTING) 177 178 void sync_mm_rss(struct mm_struct *mm) 179 { 180 int i; 181 182 for (i = 0; i < NR_MM_COUNTERS; i++) { 183 if (current->rss_stat.count[i]) { 184 add_mm_counter(mm, i, current->rss_stat.count[i]); 185 current->rss_stat.count[i] = 0; 186 } 187 } 188 current->rss_stat.events = 0; 189 } 190 191 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 192 { 193 struct task_struct *task = current; 194 195 if (likely(task->mm == mm)) 196 task->rss_stat.count[member] += val; 197 else 198 add_mm_counter(mm, member, val); 199 } 200 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 201 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 202 203 /* sync counter once per 64 page faults */ 204 #define TASK_RSS_EVENTS_THRESH (64) 205 static void check_sync_rss_stat(struct task_struct *task) 206 { 207 if (unlikely(task != current)) 208 return; 209 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 210 sync_mm_rss(task->mm); 211 } 212 #else /* SPLIT_RSS_COUNTING */ 213 214 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 215 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 216 217 static void check_sync_rss_stat(struct task_struct *task) 218 { 219 } 220 221 #endif /* SPLIT_RSS_COUNTING */ 222 223 /* 224 * Note: this doesn't free the actual pages themselves. That 225 * has been handled earlier when unmapping all the memory regions. 226 */ 227 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 228 unsigned long addr) 229 { 230 pgtable_t token = pmd_pgtable(*pmd); 231 pmd_clear(pmd); 232 pte_free_tlb(tlb, token, addr); 233 mm_dec_nr_ptes(tlb->mm); 234 } 235 236 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 237 unsigned long addr, unsigned long end, 238 unsigned long floor, unsigned long ceiling) 239 { 240 pmd_t *pmd; 241 unsigned long next; 242 unsigned long start; 243 244 start = addr; 245 pmd = pmd_offset(pud, addr); 246 do { 247 next = pmd_addr_end(addr, end); 248 if (pmd_none_or_clear_bad(pmd)) 249 continue; 250 free_pte_range(tlb, pmd, addr); 251 } while (pmd++, addr = next, addr != end); 252 253 start &= PUD_MASK; 254 if (start < floor) 255 return; 256 if (ceiling) { 257 ceiling &= PUD_MASK; 258 if (!ceiling) 259 return; 260 } 261 if (end - 1 > ceiling - 1) 262 return; 263 264 pmd = pmd_offset(pud, start); 265 pud_clear(pud); 266 pmd_free_tlb(tlb, pmd, start); 267 mm_dec_nr_pmds(tlb->mm); 268 } 269 270 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, 271 unsigned long addr, unsigned long end, 272 unsigned long floor, unsigned long ceiling) 273 { 274 pud_t *pud; 275 unsigned long next; 276 unsigned long start; 277 278 start = addr; 279 pud = pud_offset(p4d, addr); 280 do { 281 next = pud_addr_end(addr, end); 282 if (pud_none_or_clear_bad(pud)) 283 continue; 284 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 285 } while (pud++, addr = next, addr != end); 286 287 start &= P4D_MASK; 288 if (start < floor) 289 return; 290 if (ceiling) { 291 ceiling &= P4D_MASK; 292 if (!ceiling) 293 return; 294 } 295 if (end - 1 > ceiling - 1) 296 return; 297 298 pud = pud_offset(p4d, start); 299 p4d_clear(p4d); 300 pud_free_tlb(tlb, pud, start); 301 mm_dec_nr_puds(tlb->mm); 302 } 303 304 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, 305 unsigned long addr, unsigned long end, 306 unsigned long floor, unsigned long ceiling) 307 { 308 p4d_t *p4d; 309 unsigned long next; 310 unsigned long start; 311 312 start = addr; 313 p4d = p4d_offset(pgd, addr); 314 do { 315 next = p4d_addr_end(addr, end); 316 if (p4d_none_or_clear_bad(p4d)) 317 continue; 318 free_pud_range(tlb, p4d, addr, next, floor, ceiling); 319 } while (p4d++, addr = next, addr != end); 320 321 start &= PGDIR_MASK; 322 if (start < floor) 323 return; 324 if (ceiling) { 325 ceiling &= PGDIR_MASK; 326 if (!ceiling) 327 return; 328 } 329 if (end - 1 > ceiling - 1) 330 return; 331 332 p4d = p4d_offset(pgd, start); 333 pgd_clear(pgd); 334 p4d_free_tlb(tlb, p4d, start); 335 } 336 337 /* 338 * This function frees user-level page tables of a process. 339 */ 340 void free_pgd_range(struct mmu_gather *tlb, 341 unsigned long addr, unsigned long end, 342 unsigned long floor, unsigned long ceiling) 343 { 344 pgd_t *pgd; 345 unsigned long next; 346 347 /* 348 * The next few lines have given us lots of grief... 349 * 350 * Why are we testing PMD* at this top level? Because often 351 * there will be no work to do at all, and we'd prefer not to 352 * go all the way down to the bottom just to discover that. 353 * 354 * Why all these "- 1"s? Because 0 represents both the bottom 355 * of the address space and the top of it (using -1 for the 356 * top wouldn't help much: the masks would do the wrong thing). 357 * The rule is that addr 0 and floor 0 refer to the bottom of 358 * the address space, but end 0 and ceiling 0 refer to the top 359 * Comparisons need to use "end - 1" and "ceiling - 1" (though 360 * that end 0 case should be mythical). 361 * 362 * Wherever addr is brought up or ceiling brought down, we must 363 * be careful to reject "the opposite 0" before it confuses the 364 * subsequent tests. But what about where end is brought down 365 * by PMD_SIZE below? no, end can't go down to 0 there. 366 * 367 * Whereas we round start (addr) and ceiling down, by different 368 * masks at different levels, in order to test whether a table 369 * now has no other vmas using it, so can be freed, we don't 370 * bother to round floor or end up - the tests don't need that. 371 */ 372 373 addr &= PMD_MASK; 374 if (addr < floor) { 375 addr += PMD_SIZE; 376 if (!addr) 377 return; 378 } 379 if (ceiling) { 380 ceiling &= PMD_MASK; 381 if (!ceiling) 382 return; 383 } 384 if (end - 1 > ceiling - 1) 385 end -= PMD_SIZE; 386 if (addr > end - 1) 387 return; 388 /* 389 * We add page table cache pages with PAGE_SIZE, 390 * (see pte_free_tlb()), flush the tlb if we need 391 */ 392 tlb_change_page_size(tlb, PAGE_SIZE); 393 pgd = pgd_offset(tlb->mm, addr); 394 do { 395 next = pgd_addr_end(addr, end); 396 if (pgd_none_or_clear_bad(pgd)) 397 continue; 398 free_p4d_range(tlb, pgd, addr, next, floor, ceiling); 399 } while (pgd++, addr = next, addr != end); 400 } 401 402 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 403 unsigned long floor, unsigned long ceiling) 404 { 405 while (vma) { 406 struct vm_area_struct *next = vma->vm_next; 407 unsigned long addr = vma->vm_start; 408 409 /* 410 * Hide vma from rmap and truncate_pagecache before freeing 411 * pgtables 412 */ 413 unlink_anon_vmas(vma); 414 unlink_file_vma(vma); 415 416 if (is_vm_hugetlb_page(vma)) { 417 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 418 floor, next ? next->vm_start : ceiling); 419 } else { 420 /* 421 * Optimization: gather nearby vmas into one call down 422 */ 423 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 424 && !is_vm_hugetlb_page(next)) { 425 vma = next; 426 next = vma->vm_next; 427 unlink_anon_vmas(vma); 428 unlink_file_vma(vma); 429 } 430 free_pgd_range(tlb, addr, vma->vm_end, 431 floor, next ? next->vm_start : ceiling); 432 } 433 vma = next; 434 } 435 } 436 437 void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte) 438 { 439 spinlock_t *ptl = pmd_lock(mm, pmd); 440 441 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 442 mm_inc_nr_ptes(mm); 443 /* 444 * Ensure all pte setup (eg. pte page lock and page clearing) are 445 * visible before the pte is made visible to other CPUs by being 446 * put into page tables. 447 * 448 * The other side of the story is the pointer chasing in the page 449 * table walking code (when walking the page table without locking; 450 * ie. most of the time). Fortunately, these data accesses consist 451 * of a chain of data-dependent loads, meaning most CPUs (alpha 452 * being the notable exception) will already guarantee loads are 453 * seen in-order. See the alpha page table accessors for the 454 * smp_rmb() barriers in page table walking code. 455 */ 456 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 457 pmd_populate(mm, pmd, *pte); 458 *pte = NULL; 459 } 460 spin_unlock(ptl); 461 } 462 463 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd) 464 { 465 pgtable_t new = pte_alloc_one(mm); 466 if (!new) 467 return -ENOMEM; 468 469 pmd_install(mm, pmd, &new); 470 if (new) 471 pte_free(mm, new); 472 return 0; 473 } 474 475 int __pte_alloc_kernel(pmd_t *pmd) 476 { 477 pte_t *new = pte_alloc_one_kernel(&init_mm); 478 if (!new) 479 return -ENOMEM; 480 481 spin_lock(&init_mm.page_table_lock); 482 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 483 smp_wmb(); /* See comment in pmd_install() */ 484 pmd_populate_kernel(&init_mm, pmd, new); 485 new = NULL; 486 } 487 spin_unlock(&init_mm.page_table_lock); 488 if (new) 489 pte_free_kernel(&init_mm, new); 490 return 0; 491 } 492 493 static inline void init_rss_vec(int *rss) 494 { 495 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 496 } 497 498 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 499 { 500 int i; 501 502 if (current->mm == mm) 503 sync_mm_rss(mm); 504 for (i = 0; i < NR_MM_COUNTERS; i++) 505 if (rss[i]) 506 add_mm_counter(mm, i, rss[i]); 507 } 508 509 /* 510 * This function is called to print an error when a bad pte 511 * is found. For example, we might have a PFN-mapped pte in 512 * a region that doesn't allow it. 513 * 514 * The calling function must still handle the error. 515 */ 516 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 517 pte_t pte, struct page *page) 518 { 519 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 520 p4d_t *p4d = p4d_offset(pgd, addr); 521 pud_t *pud = pud_offset(p4d, addr); 522 pmd_t *pmd = pmd_offset(pud, addr); 523 struct address_space *mapping; 524 pgoff_t index; 525 static unsigned long resume; 526 static unsigned long nr_shown; 527 static unsigned long nr_unshown; 528 529 /* 530 * Allow a burst of 60 reports, then keep quiet for that minute; 531 * or allow a steady drip of one report per second. 532 */ 533 if (nr_shown == 60) { 534 if (time_before(jiffies, resume)) { 535 nr_unshown++; 536 return; 537 } 538 if (nr_unshown) { 539 pr_alert("BUG: Bad page map: %lu messages suppressed\n", 540 nr_unshown); 541 nr_unshown = 0; 542 } 543 nr_shown = 0; 544 } 545 if (nr_shown++ == 0) 546 resume = jiffies + 60 * HZ; 547 548 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 549 index = linear_page_index(vma, addr); 550 551 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 552 current->comm, 553 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 554 if (page) 555 dump_page(page, "bad pte"); 556 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n", 557 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 558 pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n", 559 vma->vm_file, 560 vma->vm_ops ? vma->vm_ops->fault : NULL, 561 vma->vm_file ? vma->vm_file->f_op->mmap : NULL, 562 mapping ? mapping->a_ops->readpage : NULL); 563 dump_stack(); 564 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 565 } 566 567 /* 568 * vm_normal_page -- This function gets the "struct page" associated with a pte. 569 * 570 * "Special" mappings do not wish to be associated with a "struct page" (either 571 * it doesn't exist, or it exists but they don't want to touch it). In this 572 * case, NULL is returned here. "Normal" mappings do have a struct page. 573 * 574 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 575 * pte bit, in which case this function is trivial. Secondly, an architecture 576 * may not have a spare pte bit, which requires a more complicated scheme, 577 * described below. 578 * 579 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 580 * special mapping (even if there are underlying and valid "struct pages"). 581 * COWed pages of a VM_PFNMAP are always normal. 582 * 583 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 584 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 585 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 586 * mapping will always honor the rule 587 * 588 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 589 * 590 * And for normal mappings this is false. 591 * 592 * This restricts such mappings to be a linear translation from virtual address 593 * to pfn. To get around this restriction, we allow arbitrary mappings so long 594 * as the vma is not a COW mapping; in that case, we know that all ptes are 595 * special (because none can have been COWed). 596 * 597 * 598 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 599 * 600 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 601 * page" backing, however the difference is that _all_ pages with a struct 602 * page (that is, those where pfn_valid is true) are refcounted and considered 603 * normal pages by the VM. The disadvantage is that pages are refcounted 604 * (which can be slower and simply not an option for some PFNMAP users). The 605 * advantage is that we don't have to follow the strict linearity rule of 606 * PFNMAP mappings in order to support COWable mappings. 607 * 608 */ 609 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 610 pte_t pte) 611 { 612 unsigned long pfn = pte_pfn(pte); 613 614 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { 615 if (likely(!pte_special(pte))) 616 goto check_pfn; 617 if (vma->vm_ops && vma->vm_ops->find_special_page) 618 return vma->vm_ops->find_special_page(vma, addr); 619 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 620 return NULL; 621 if (is_zero_pfn(pfn)) 622 return NULL; 623 if (pte_devmap(pte)) 624 return NULL; 625 626 print_bad_pte(vma, addr, pte, NULL); 627 return NULL; 628 } 629 630 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ 631 632 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 633 if (vma->vm_flags & VM_MIXEDMAP) { 634 if (!pfn_valid(pfn)) 635 return NULL; 636 goto out; 637 } else { 638 unsigned long off; 639 off = (addr - vma->vm_start) >> PAGE_SHIFT; 640 if (pfn == vma->vm_pgoff + off) 641 return NULL; 642 if (!is_cow_mapping(vma->vm_flags)) 643 return NULL; 644 } 645 } 646 647 if (is_zero_pfn(pfn)) 648 return NULL; 649 650 check_pfn: 651 if (unlikely(pfn > highest_memmap_pfn)) { 652 print_bad_pte(vma, addr, pte, NULL); 653 return NULL; 654 } 655 656 /* 657 * NOTE! We still have PageReserved() pages in the page tables. 658 * eg. VDSO mappings can cause them to exist. 659 */ 660 out: 661 return pfn_to_page(pfn); 662 } 663 664 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 665 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, 666 pmd_t pmd) 667 { 668 unsigned long pfn = pmd_pfn(pmd); 669 670 /* 671 * There is no pmd_special() but there may be special pmds, e.g. 672 * in a direct-access (dax) mapping, so let's just replicate the 673 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. 674 */ 675 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 676 if (vma->vm_flags & VM_MIXEDMAP) { 677 if (!pfn_valid(pfn)) 678 return NULL; 679 goto out; 680 } else { 681 unsigned long off; 682 off = (addr - vma->vm_start) >> PAGE_SHIFT; 683 if (pfn == vma->vm_pgoff + off) 684 return NULL; 685 if (!is_cow_mapping(vma->vm_flags)) 686 return NULL; 687 } 688 } 689 690 if (pmd_devmap(pmd)) 691 return NULL; 692 if (is_huge_zero_pmd(pmd)) 693 return NULL; 694 if (unlikely(pfn > highest_memmap_pfn)) 695 return NULL; 696 697 /* 698 * NOTE! We still have PageReserved() pages in the page tables. 699 * eg. VDSO mappings can cause them to exist. 700 */ 701 out: 702 return pfn_to_page(pfn); 703 } 704 #endif 705 706 static void restore_exclusive_pte(struct vm_area_struct *vma, 707 struct page *page, unsigned long address, 708 pte_t *ptep) 709 { 710 pte_t pte; 711 swp_entry_t entry; 712 713 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); 714 if (pte_swp_soft_dirty(*ptep)) 715 pte = pte_mksoft_dirty(pte); 716 717 entry = pte_to_swp_entry(*ptep); 718 if (pte_swp_uffd_wp(*ptep)) 719 pte = pte_mkuffd_wp(pte); 720 else if (is_writable_device_exclusive_entry(entry)) 721 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 722 723 /* 724 * No need to take a page reference as one was already 725 * created when the swap entry was made. 726 */ 727 if (PageAnon(page)) 728 page_add_anon_rmap(page, vma, address, false); 729 else 730 /* 731 * Currently device exclusive access only supports anonymous 732 * memory so the entry shouldn't point to a filebacked page. 733 */ 734 WARN_ON_ONCE(!PageAnon(page)); 735 736 set_pte_at(vma->vm_mm, address, ptep, pte); 737 738 /* 739 * No need to invalidate - it was non-present before. However 740 * secondary CPUs may have mappings that need invalidating. 741 */ 742 update_mmu_cache(vma, address, ptep); 743 } 744 745 /* 746 * Tries to restore an exclusive pte if the page lock can be acquired without 747 * sleeping. 748 */ 749 static int 750 try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, 751 unsigned long addr) 752 { 753 swp_entry_t entry = pte_to_swp_entry(*src_pte); 754 struct page *page = pfn_swap_entry_to_page(entry); 755 756 if (trylock_page(page)) { 757 restore_exclusive_pte(vma, page, addr, src_pte); 758 unlock_page(page); 759 return 0; 760 } 761 762 return -EBUSY; 763 } 764 765 /* 766 * copy one vm_area from one task to the other. Assumes the page tables 767 * already present in the new task to be cleared in the whole range 768 * covered by this vma. 769 */ 770 771 static unsigned long 772 copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 773 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, 774 struct vm_area_struct *src_vma, unsigned long addr, int *rss) 775 { 776 unsigned long vm_flags = dst_vma->vm_flags; 777 pte_t pte = *src_pte; 778 struct page *page; 779 swp_entry_t entry = pte_to_swp_entry(pte); 780 781 if (likely(!non_swap_entry(entry))) { 782 if (swap_duplicate(entry) < 0) 783 return -EIO; 784 785 /* make sure dst_mm is on swapoff's mmlist. */ 786 if (unlikely(list_empty(&dst_mm->mmlist))) { 787 spin_lock(&mmlist_lock); 788 if (list_empty(&dst_mm->mmlist)) 789 list_add(&dst_mm->mmlist, 790 &src_mm->mmlist); 791 spin_unlock(&mmlist_lock); 792 } 793 rss[MM_SWAPENTS]++; 794 } else if (is_migration_entry(entry)) { 795 page = pfn_swap_entry_to_page(entry); 796 797 rss[mm_counter(page)]++; 798 799 if (is_writable_migration_entry(entry) && 800 is_cow_mapping(vm_flags)) { 801 /* 802 * COW mappings require pages in both 803 * parent and child to be set to read. 804 */ 805 entry = make_readable_migration_entry( 806 swp_offset(entry)); 807 pte = swp_entry_to_pte(entry); 808 if (pte_swp_soft_dirty(*src_pte)) 809 pte = pte_swp_mksoft_dirty(pte); 810 if (pte_swp_uffd_wp(*src_pte)) 811 pte = pte_swp_mkuffd_wp(pte); 812 set_pte_at(src_mm, addr, src_pte, pte); 813 } 814 } else if (is_device_private_entry(entry)) { 815 page = pfn_swap_entry_to_page(entry); 816 817 /* 818 * Update rss count even for unaddressable pages, as 819 * they should treated just like normal pages in this 820 * respect. 821 * 822 * We will likely want to have some new rss counters 823 * for unaddressable pages, at some point. But for now 824 * keep things as they are. 825 */ 826 get_page(page); 827 rss[mm_counter(page)]++; 828 page_dup_rmap(page, false); 829 830 /* 831 * We do not preserve soft-dirty information, because so 832 * far, checkpoint/restore is the only feature that 833 * requires that. And checkpoint/restore does not work 834 * when a device driver is involved (you cannot easily 835 * save and restore device driver state). 836 */ 837 if (is_writable_device_private_entry(entry) && 838 is_cow_mapping(vm_flags)) { 839 entry = make_readable_device_private_entry( 840 swp_offset(entry)); 841 pte = swp_entry_to_pte(entry); 842 if (pte_swp_uffd_wp(*src_pte)) 843 pte = pte_swp_mkuffd_wp(pte); 844 set_pte_at(src_mm, addr, src_pte, pte); 845 } 846 } else if (is_device_exclusive_entry(entry)) { 847 /* 848 * Make device exclusive entries present by restoring the 849 * original entry then copying as for a present pte. Device 850 * exclusive entries currently only support private writable 851 * (ie. COW) mappings. 852 */ 853 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); 854 if (try_restore_exclusive_pte(src_pte, src_vma, addr)) 855 return -EBUSY; 856 return -ENOENT; 857 } 858 if (!userfaultfd_wp(dst_vma)) 859 pte = pte_swp_clear_uffd_wp(pte); 860 set_pte_at(dst_mm, addr, dst_pte, pte); 861 return 0; 862 } 863 864 /* 865 * Copy a present and normal page if necessary. 866 * 867 * NOTE! The usual case is that this doesn't need to do 868 * anything, and can just return a positive value. That 869 * will let the caller know that it can just increase 870 * the page refcount and re-use the pte the traditional 871 * way. 872 * 873 * But _if_ we need to copy it because it needs to be 874 * pinned in the parent (and the child should get its own 875 * copy rather than just a reference to the same page), 876 * we'll do that here and return zero to let the caller 877 * know we're done. 878 * 879 * And if we need a pre-allocated page but don't yet have 880 * one, return a negative error to let the preallocation 881 * code know so that it can do so outside the page table 882 * lock. 883 */ 884 static inline int 885 copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 886 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, 887 struct page **prealloc, pte_t pte, struct page *page) 888 { 889 struct page *new_page; 890 891 /* 892 * What we want to do is to check whether this page may 893 * have been pinned by the parent process. If so, 894 * instead of wrprotect the pte on both sides, we copy 895 * the page immediately so that we'll always guarantee 896 * the pinned page won't be randomly replaced in the 897 * future. 898 * 899 * The page pinning checks are just "has this mm ever 900 * seen pinning", along with the (inexact) check of 901 * the page count. That might give false positives for 902 * for pinning, but it will work correctly. 903 */ 904 if (likely(!page_needs_cow_for_dma(src_vma, page))) 905 return 1; 906 907 new_page = *prealloc; 908 if (!new_page) 909 return -EAGAIN; 910 911 /* 912 * We have a prealloc page, all good! Take it 913 * over and copy the page & arm it. 914 */ 915 *prealloc = NULL; 916 copy_user_highpage(new_page, page, addr, src_vma); 917 __SetPageUptodate(new_page); 918 page_add_new_anon_rmap(new_page, dst_vma, addr, false); 919 lru_cache_add_inactive_or_unevictable(new_page, dst_vma); 920 rss[mm_counter(new_page)]++; 921 922 /* All done, just insert the new page copy in the child */ 923 pte = mk_pte(new_page, dst_vma->vm_page_prot); 924 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma); 925 if (userfaultfd_pte_wp(dst_vma, *src_pte)) 926 /* Uffd-wp needs to be delivered to dest pte as well */ 927 pte = pte_wrprotect(pte_mkuffd_wp(pte)); 928 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); 929 return 0; 930 } 931 932 /* 933 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page 934 * is required to copy this pte. 935 */ 936 static inline int 937 copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 938 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, 939 struct page **prealloc) 940 { 941 struct mm_struct *src_mm = src_vma->vm_mm; 942 unsigned long vm_flags = src_vma->vm_flags; 943 pte_t pte = *src_pte; 944 struct page *page; 945 946 page = vm_normal_page(src_vma, addr, pte); 947 if (page) { 948 int retval; 949 950 retval = copy_present_page(dst_vma, src_vma, dst_pte, src_pte, 951 addr, rss, prealloc, pte, page); 952 if (retval <= 0) 953 return retval; 954 955 get_page(page); 956 page_dup_rmap(page, false); 957 rss[mm_counter(page)]++; 958 } 959 960 /* 961 * If it's a COW mapping, write protect it both 962 * in the parent and the child 963 */ 964 if (is_cow_mapping(vm_flags) && pte_write(pte)) { 965 ptep_set_wrprotect(src_mm, addr, src_pte); 966 pte = pte_wrprotect(pte); 967 } 968 969 /* 970 * If it's a shared mapping, mark it clean in 971 * the child 972 */ 973 if (vm_flags & VM_SHARED) 974 pte = pte_mkclean(pte); 975 pte = pte_mkold(pte); 976 977 if (!userfaultfd_wp(dst_vma)) 978 pte = pte_clear_uffd_wp(pte); 979 980 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); 981 return 0; 982 } 983 984 static inline struct page * 985 page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma, 986 unsigned long addr) 987 { 988 struct page *new_page; 989 990 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr); 991 if (!new_page) 992 return NULL; 993 994 if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) { 995 put_page(new_page); 996 return NULL; 997 } 998 cgroup_throttle_swaprate(new_page, GFP_KERNEL); 999 1000 return new_page; 1001 } 1002 1003 static int 1004 copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 1005 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1006 unsigned long end) 1007 { 1008 struct mm_struct *dst_mm = dst_vma->vm_mm; 1009 struct mm_struct *src_mm = src_vma->vm_mm; 1010 pte_t *orig_src_pte, *orig_dst_pte; 1011 pte_t *src_pte, *dst_pte; 1012 spinlock_t *src_ptl, *dst_ptl; 1013 int progress, ret = 0; 1014 int rss[NR_MM_COUNTERS]; 1015 swp_entry_t entry = (swp_entry_t){0}; 1016 struct page *prealloc = NULL; 1017 1018 again: 1019 progress = 0; 1020 init_rss_vec(rss); 1021 1022 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 1023 if (!dst_pte) { 1024 ret = -ENOMEM; 1025 goto out; 1026 } 1027 src_pte = pte_offset_map(src_pmd, addr); 1028 src_ptl = pte_lockptr(src_mm, src_pmd); 1029 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1030 orig_src_pte = src_pte; 1031 orig_dst_pte = dst_pte; 1032 arch_enter_lazy_mmu_mode(); 1033 1034 do { 1035 /* 1036 * We are holding two locks at this point - either of them 1037 * could generate latencies in another task on another CPU. 1038 */ 1039 if (progress >= 32) { 1040 progress = 0; 1041 if (need_resched() || 1042 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 1043 break; 1044 } 1045 if (pte_none(*src_pte)) { 1046 progress++; 1047 continue; 1048 } 1049 if (unlikely(!pte_present(*src_pte))) { 1050 ret = copy_nonpresent_pte(dst_mm, src_mm, 1051 dst_pte, src_pte, 1052 dst_vma, src_vma, 1053 addr, rss); 1054 if (ret == -EIO) { 1055 entry = pte_to_swp_entry(*src_pte); 1056 break; 1057 } else if (ret == -EBUSY) { 1058 break; 1059 } else if (!ret) { 1060 progress += 8; 1061 continue; 1062 } 1063 1064 /* 1065 * Device exclusive entry restored, continue by copying 1066 * the now present pte. 1067 */ 1068 WARN_ON_ONCE(ret != -ENOENT); 1069 } 1070 /* copy_present_pte() will clear `*prealloc' if consumed */ 1071 ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte, 1072 addr, rss, &prealloc); 1073 /* 1074 * If we need a pre-allocated page for this pte, drop the 1075 * locks, allocate, and try again. 1076 */ 1077 if (unlikely(ret == -EAGAIN)) 1078 break; 1079 if (unlikely(prealloc)) { 1080 /* 1081 * pre-alloc page cannot be reused by next time so as 1082 * to strictly follow mempolicy (e.g., alloc_page_vma() 1083 * will allocate page according to address). This 1084 * could only happen if one pinned pte changed. 1085 */ 1086 put_page(prealloc); 1087 prealloc = NULL; 1088 } 1089 progress += 8; 1090 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 1091 1092 arch_leave_lazy_mmu_mode(); 1093 spin_unlock(src_ptl); 1094 pte_unmap(orig_src_pte); 1095 add_mm_rss_vec(dst_mm, rss); 1096 pte_unmap_unlock(orig_dst_pte, dst_ptl); 1097 cond_resched(); 1098 1099 if (ret == -EIO) { 1100 VM_WARN_ON_ONCE(!entry.val); 1101 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { 1102 ret = -ENOMEM; 1103 goto out; 1104 } 1105 entry.val = 0; 1106 } else if (ret == -EBUSY) { 1107 goto out; 1108 } else if (ret == -EAGAIN) { 1109 prealloc = page_copy_prealloc(src_mm, src_vma, addr); 1110 if (!prealloc) 1111 return -ENOMEM; 1112 } else if (ret) { 1113 VM_WARN_ON_ONCE(1); 1114 } 1115 1116 /* We've captured and resolved the error. Reset, try again. */ 1117 ret = 0; 1118 1119 if (addr != end) 1120 goto again; 1121 out: 1122 if (unlikely(prealloc)) 1123 put_page(prealloc); 1124 return ret; 1125 } 1126 1127 static inline int 1128 copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 1129 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1130 unsigned long end) 1131 { 1132 struct mm_struct *dst_mm = dst_vma->vm_mm; 1133 struct mm_struct *src_mm = src_vma->vm_mm; 1134 pmd_t *src_pmd, *dst_pmd; 1135 unsigned long next; 1136 1137 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 1138 if (!dst_pmd) 1139 return -ENOMEM; 1140 src_pmd = pmd_offset(src_pud, addr); 1141 do { 1142 next = pmd_addr_end(addr, end); 1143 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) 1144 || pmd_devmap(*src_pmd)) { 1145 int err; 1146 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma); 1147 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd, 1148 addr, dst_vma, src_vma); 1149 if (err == -ENOMEM) 1150 return -ENOMEM; 1151 if (!err) 1152 continue; 1153 /* fall through */ 1154 } 1155 if (pmd_none_or_clear_bad(src_pmd)) 1156 continue; 1157 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd, 1158 addr, next)) 1159 return -ENOMEM; 1160 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 1161 return 0; 1162 } 1163 1164 static inline int 1165 copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 1166 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr, 1167 unsigned long end) 1168 { 1169 struct mm_struct *dst_mm = dst_vma->vm_mm; 1170 struct mm_struct *src_mm = src_vma->vm_mm; 1171 pud_t *src_pud, *dst_pud; 1172 unsigned long next; 1173 1174 dst_pud = pud_alloc(dst_mm, dst_p4d, addr); 1175 if (!dst_pud) 1176 return -ENOMEM; 1177 src_pud = pud_offset(src_p4d, addr); 1178 do { 1179 next = pud_addr_end(addr, end); 1180 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { 1181 int err; 1182 1183 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma); 1184 err = copy_huge_pud(dst_mm, src_mm, 1185 dst_pud, src_pud, addr, src_vma); 1186 if (err == -ENOMEM) 1187 return -ENOMEM; 1188 if (!err) 1189 continue; 1190 /* fall through */ 1191 } 1192 if (pud_none_or_clear_bad(src_pud)) 1193 continue; 1194 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud, 1195 addr, next)) 1196 return -ENOMEM; 1197 } while (dst_pud++, src_pud++, addr = next, addr != end); 1198 return 0; 1199 } 1200 1201 static inline int 1202 copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 1203 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr, 1204 unsigned long end) 1205 { 1206 struct mm_struct *dst_mm = dst_vma->vm_mm; 1207 p4d_t *src_p4d, *dst_p4d; 1208 unsigned long next; 1209 1210 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); 1211 if (!dst_p4d) 1212 return -ENOMEM; 1213 src_p4d = p4d_offset(src_pgd, addr); 1214 do { 1215 next = p4d_addr_end(addr, end); 1216 if (p4d_none_or_clear_bad(src_p4d)) 1217 continue; 1218 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d, 1219 addr, next)) 1220 return -ENOMEM; 1221 } while (dst_p4d++, src_p4d++, addr = next, addr != end); 1222 return 0; 1223 } 1224 1225 int 1226 copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1227 { 1228 pgd_t *src_pgd, *dst_pgd; 1229 unsigned long next; 1230 unsigned long addr = src_vma->vm_start; 1231 unsigned long end = src_vma->vm_end; 1232 struct mm_struct *dst_mm = dst_vma->vm_mm; 1233 struct mm_struct *src_mm = src_vma->vm_mm; 1234 struct mmu_notifier_range range; 1235 bool is_cow; 1236 int ret; 1237 1238 /* 1239 * Don't copy ptes where a page fault will fill them correctly. 1240 * Fork becomes much lighter when there are big shared or private 1241 * readonly mappings. The tradeoff is that copy_page_range is more 1242 * efficient than faulting. 1243 */ 1244 if (!(src_vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) && 1245 !src_vma->anon_vma) 1246 return 0; 1247 1248 if (is_vm_hugetlb_page(src_vma)) 1249 return copy_hugetlb_page_range(dst_mm, src_mm, src_vma); 1250 1251 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { 1252 /* 1253 * We do not free on error cases below as remove_vma 1254 * gets called on error from higher level routine 1255 */ 1256 ret = track_pfn_copy(src_vma); 1257 if (ret) 1258 return ret; 1259 } 1260 1261 /* 1262 * We need to invalidate the secondary MMU mappings only when 1263 * there could be a permission downgrade on the ptes of the 1264 * parent mm. And a permission downgrade will only happen if 1265 * is_cow_mapping() returns true. 1266 */ 1267 is_cow = is_cow_mapping(src_vma->vm_flags); 1268 1269 if (is_cow) { 1270 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 1271 0, src_vma, src_mm, addr, end); 1272 mmu_notifier_invalidate_range_start(&range); 1273 /* 1274 * Disabling preemption is not needed for the write side, as 1275 * the read side doesn't spin, but goes to the mmap_lock. 1276 * 1277 * Use the raw variant of the seqcount_t write API to avoid 1278 * lockdep complaining about preemptibility. 1279 */ 1280 mmap_assert_write_locked(src_mm); 1281 raw_write_seqcount_begin(&src_mm->write_protect_seq); 1282 } 1283 1284 ret = 0; 1285 dst_pgd = pgd_offset(dst_mm, addr); 1286 src_pgd = pgd_offset(src_mm, addr); 1287 do { 1288 next = pgd_addr_end(addr, end); 1289 if (pgd_none_or_clear_bad(src_pgd)) 1290 continue; 1291 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, 1292 addr, next))) { 1293 ret = -ENOMEM; 1294 break; 1295 } 1296 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1297 1298 if (is_cow) { 1299 raw_write_seqcount_end(&src_mm->write_protect_seq); 1300 mmu_notifier_invalidate_range_end(&range); 1301 } 1302 return ret; 1303 } 1304 1305 /* 1306 * Parameter block passed down to zap_pte_range in exceptional cases. 1307 */ 1308 struct zap_details { 1309 struct folio *single_folio; /* Locked folio to be unmapped */ 1310 bool even_cows; /* Zap COWed private pages too? */ 1311 }; 1312 1313 /* Whether we should zap all COWed (private) pages too */ 1314 static inline bool should_zap_cows(struct zap_details *details) 1315 { 1316 /* By default, zap all pages */ 1317 if (!details) 1318 return true; 1319 1320 /* Or, we zap COWed pages only if the caller wants to */ 1321 return details->even_cows; 1322 } 1323 1324 /* Decides whether we should zap this page with the page pointer specified */ 1325 static inline bool should_zap_page(struct zap_details *details, struct page *page) 1326 { 1327 /* If we can make a decision without *page.. */ 1328 if (should_zap_cows(details)) 1329 return true; 1330 1331 /* E.g. the caller passes NULL for the case of a zero page */ 1332 if (!page) 1333 return true; 1334 1335 /* Otherwise we should only zap non-anon pages */ 1336 return !PageAnon(page); 1337 } 1338 1339 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1340 struct vm_area_struct *vma, pmd_t *pmd, 1341 unsigned long addr, unsigned long end, 1342 struct zap_details *details) 1343 { 1344 struct mm_struct *mm = tlb->mm; 1345 int force_flush = 0; 1346 int rss[NR_MM_COUNTERS]; 1347 spinlock_t *ptl; 1348 pte_t *start_pte; 1349 pte_t *pte; 1350 swp_entry_t entry; 1351 1352 tlb_change_page_size(tlb, PAGE_SIZE); 1353 again: 1354 init_rss_vec(rss); 1355 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1356 pte = start_pte; 1357 flush_tlb_batched_pending(mm); 1358 arch_enter_lazy_mmu_mode(); 1359 do { 1360 pte_t ptent = *pte; 1361 struct page *page; 1362 1363 if (pte_none(ptent)) 1364 continue; 1365 1366 if (need_resched()) 1367 break; 1368 1369 if (pte_present(ptent)) { 1370 page = vm_normal_page(vma, addr, ptent); 1371 if (unlikely(!should_zap_page(details, page))) 1372 continue; 1373 ptent = ptep_get_and_clear_full(mm, addr, pte, 1374 tlb->fullmm); 1375 tlb_remove_tlb_entry(tlb, pte, addr); 1376 if (unlikely(!page)) 1377 continue; 1378 1379 if (!PageAnon(page)) { 1380 if (pte_dirty(ptent)) { 1381 force_flush = 1; 1382 set_page_dirty(page); 1383 } 1384 if (pte_young(ptent) && 1385 likely(!(vma->vm_flags & VM_SEQ_READ))) 1386 mark_page_accessed(page); 1387 } 1388 rss[mm_counter(page)]--; 1389 page_remove_rmap(page, vma, false); 1390 if (unlikely(page_mapcount(page) < 0)) 1391 print_bad_pte(vma, addr, ptent, page); 1392 if (unlikely(__tlb_remove_page(tlb, page))) { 1393 force_flush = 1; 1394 addr += PAGE_SIZE; 1395 break; 1396 } 1397 continue; 1398 } 1399 1400 entry = pte_to_swp_entry(ptent); 1401 if (is_device_private_entry(entry) || 1402 is_device_exclusive_entry(entry)) { 1403 page = pfn_swap_entry_to_page(entry); 1404 if (unlikely(!should_zap_page(details, page))) 1405 continue; 1406 rss[mm_counter(page)]--; 1407 if (is_device_private_entry(entry)) 1408 page_remove_rmap(page, vma, false); 1409 put_page(page); 1410 } else if (!non_swap_entry(entry)) { 1411 /* Genuine swap entry, hence a private anon page */ 1412 if (!should_zap_cows(details)) 1413 continue; 1414 rss[MM_SWAPENTS]--; 1415 if (unlikely(!free_swap_and_cache(entry))) 1416 print_bad_pte(vma, addr, ptent, NULL); 1417 } else if (is_migration_entry(entry)) { 1418 page = pfn_swap_entry_to_page(entry); 1419 if (!should_zap_page(details, page)) 1420 continue; 1421 rss[mm_counter(page)]--; 1422 } else if (is_hwpoison_entry(entry)) { 1423 if (!should_zap_cows(details)) 1424 continue; 1425 } else { 1426 /* We should have covered all the swap entry types */ 1427 WARN_ON_ONCE(1); 1428 } 1429 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1430 } while (pte++, addr += PAGE_SIZE, addr != end); 1431 1432 add_mm_rss_vec(mm, rss); 1433 arch_leave_lazy_mmu_mode(); 1434 1435 /* Do the actual TLB flush before dropping ptl */ 1436 if (force_flush) 1437 tlb_flush_mmu_tlbonly(tlb); 1438 pte_unmap_unlock(start_pte, ptl); 1439 1440 /* 1441 * If we forced a TLB flush (either due to running out of 1442 * batch buffers or because we needed to flush dirty TLB 1443 * entries before releasing the ptl), free the batched 1444 * memory too. Restart if we didn't do everything. 1445 */ 1446 if (force_flush) { 1447 force_flush = 0; 1448 tlb_flush_mmu(tlb); 1449 } 1450 1451 if (addr != end) { 1452 cond_resched(); 1453 goto again; 1454 } 1455 1456 return addr; 1457 } 1458 1459 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1460 struct vm_area_struct *vma, pud_t *pud, 1461 unsigned long addr, unsigned long end, 1462 struct zap_details *details) 1463 { 1464 pmd_t *pmd; 1465 unsigned long next; 1466 1467 pmd = pmd_offset(pud, addr); 1468 do { 1469 next = pmd_addr_end(addr, end); 1470 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { 1471 if (next - addr != HPAGE_PMD_SIZE) 1472 __split_huge_pmd(vma, pmd, addr, false, NULL); 1473 else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1474 goto next; 1475 /* fall through */ 1476 } else if (details && details->single_folio && 1477 folio_test_pmd_mappable(details->single_folio) && 1478 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) { 1479 spinlock_t *ptl = pmd_lock(tlb->mm, pmd); 1480 /* 1481 * Take and drop THP pmd lock so that we cannot return 1482 * prematurely, while zap_huge_pmd() has cleared *pmd, 1483 * but not yet decremented compound_mapcount(). 1484 */ 1485 spin_unlock(ptl); 1486 } 1487 1488 /* 1489 * Here there can be other concurrent MADV_DONTNEED or 1490 * trans huge page faults running, and if the pmd is 1491 * none or trans huge it can change under us. This is 1492 * because MADV_DONTNEED holds the mmap_lock in read 1493 * mode. 1494 */ 1495 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1496 goto next; 1497 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1498 next: 1499 cond_resched(); 1500 } while (pmd++, addr = next, addr != end); 1501 1502 return addr; 1503 } 1504 1505 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1506 struct vm_area_struct *vma, p4d_t *p4d, 1507 unsigned long addr, unsigned long end, 1508 struct zap_details *details) 1509 { 1510 pud_t *pud; 1511 unsigned long next; 1512 1513 pud = pud_offset(p4d, addr); 1514 do { 1515 next = pud_addr_end(addr, end); 1516 if (pud_trans_huge(*pud) || pud_devmap(*pud)) { 1517 if (next - addr != HPAGE_PUD_SIZE) { 1518 mmap_assert_locked(tlb->mm); 1519 split_huge_pud(vma, pud, addr); 1520 } else if (zap_huge_pud(tlb, vma, pud, addr)) 1521 goto next; 1522 /* fall through */ 1523 } 1524 if (pud_none_or_clear_bad(pud)) 1525 continue; 1526 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1527 next: 1528 cond_resched(); 1529 } while (pud++, addr = next, addr != end); 1530 1531 return addr; 1532 } 1533 1534 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, 1535 struct vm_area_struct *vma, pgd_t *pgd, 1536 unsigned long addr, unsigned long end, 1537 struct zap_details *details) 1538 { 1539 p4d_t *p4d; 1540 unsigned long next; 1541 1542 p4d = p4d_offset(pgd, addr); 1543 do { 1544 next = p4d_addr_end(addr, end); 1545 if (p4d_none_or_clear_bad(p4d)) 1546 continue; 1547 next = zap_pud_range(tlb, vma, p4d, addr, next, details); 1548 } while (p4d++, addr = next, addr != end); 1549 1550 return addr; 1551 } 1552 1553 void unmap_page_range(struct mmu_gather *tlb, 1554 struct vm_area_struct *vma, 1555 unsigned long addr, unsigned long end, 1556 struct zap_details *details) 1557 { 1558 pgd_t *pgd; 1559 unsigned long next; 1560 1561 BUG_ON(addr >= end); 1562 tlb_start_vma(tlb, vma); 1563 pgd = pgd_offset(vma->vm_mm, addr); 1564 do { 1565 next = pgd_addr_end(addr, end); 1566 if (pgd_none_or_clear_bad(pgd)) 1567 continue; 1568 next = zap_p4d_range(tlb, vma, pgd, addr, next, details); 1569 } while (pgd++, addr = next, addr != end); 1570 tlb_end_vma(tlb, vma); 1571 } 1572 1573 1574 static void unmap_single_vma(struct mmu_gather *tlb, 1575 struct vm_area_struct *vma, unsigned long start_addr, 1576 unsigned long end_addr, 1577 struct zap_details *details) 1578 { 1579 unsigned long start = max(vma->vm_start, start_addr); 1580 unsigned long end; 1581 1582 if (start >= vma->vm_end) 1583 return; 1584 end = min(vma->vm_end, end_addr); 1585 if (end <= vma->vm_start) 1586 return; 1587 1588 if (vma->vm_file) 1589 uprobe_munmap(vma, start, end); 1590 1591 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1592 untrack_pfn(vma, 0, 0); 1593 1594 if (start != end) { 1595 if (unlikely(is_vm_hugetlb_page(vma))) { 1596 /* 1597 * It is undesirable to test vma->vm_file as it 1598 * should be non-null for valid hugetlb area. 1599 * However, vm_file will be NULL in the error 1600 * cleanup path of mmap_region. When 1601 * hugetlbfs ->mmap method fails, 1602 * mmap_region() nullifies vma->vm_file 1603 * before calling this function to clean up. 1604 * Since no pte has actually been setup, it is 1605 * safe to do nothing in this case. 1606 */ 1607 if (vma->vm_file) { 1608 i_mmap_lock_write(vma->vm_file->f_mapping); 1609 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1610 i_mmap_unlock_write(vma->vm_file->f_mapping); 1611 } 1612 } else 1613 unmap_page_range(tlb, vma, start, end, details); 1614 } 1615 } 1616 1617 /** 1618 * unmap_vmas - unmap a range of memory covered by a list of vma's 1619 * @tlb: address of the caller's struct mmu_gather 1620 * @vma: the starting vma 1621 * @start_addr: virtual address at which to start unmapping 1622 * @end_addr: virtual address at which to end unmapping 1623 * 1624 * Unmap all pages in the vma list. 1625 * 1626 * Only addresses between `start' and `end' will be unmapped. 1627 * 1628 * The VMA list must be sorted in ascending virtual address order. 1629 * 1630 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1631 * range after unmap_vmas() returns. So the only responsibility here is to 1632 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1633 * drops the lock and schedules. 1634 */ 1635 void unmap_vmas(struct mmu_gather *tlb, 1636 struct vm_area_struct *vma, unsigned long start_addr, 1637 unsigned long end_addr) 1638 { 1639 struct mmu_notifier_range range; 1640 1641 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm, 1642 start_addr, end_addr); 1643 mmu_notifier_invalidate_range_start(&range); 1644 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1645 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1646 mmu_notifier_invalidate_range_end(&range); 1647 } 1648 1649 /** 1650 * zap_page_range - remove user pages in a given range 1651 * @vma: vm_area_struct holding the applicable pages 1652 * @start: starting address of pages to zap 1653 * @size: number of bytes to zap 1654 * 1655 * Caller must protect the VMA list 1656 */ 1657 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1658 unsigned long size) 1659 { 1660 struct mmu_notifier_range range; 1661 struct mmu_gather tlb; 1662 1663 lru_add_drain(); 1664 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1665 start, start + size); 1666 tlb_gather_mmu(&tlb, vma->vm_mm); 1667 update_hiwater_rss(vma->vm_mm); 1668 mmu_notifier_invalidate_range_start(&range); 1669 for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next) 1670 unmap_single_vma(&tlb, vma, start, range.end, NULL); 1671 mmu_notifier_invalidate_range_end(&range); 1672 tlb_finish_mmu(&tlb); 1673 } 1674 1675 /** 1676 * zap_page_range_single - remove user pages in a given range 1677 * @vma: vm_area_struct holding the applicable pages 1678 * @address: starting address of pages to zap 1679 * @size: number of bytes to zap 1680 * @details: details of shared cache invalidation 1681 * 1682 * The range must fit into one VMA. 1683 */ 1684 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1685 unsigned long size, struct zap_details *details) 1686 { 1687 struct mmu_notifier_range range; 1688 struct mmu_gather tlb; 1689 1690 lru_add_drain(); 1691 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1692 address, address + size); 1693 tlb_gather_mmu(&tlb, vma->vm_mm); 1694 update_hiwater_rss(vma->vm_mm); 1695 mmu_notifier_invalidate_range_start(&range); 1696 unmap_single_vma(&tlb, vma, address, range.end, details); 1697 mmu_notifier_invalidate_range_end(&range); 1698 tlb_finish_mmu(&tlb); 1699 } 1700 1701 /** 1702 * zap_vma_ptes - remove ptes mapping the vma 1703 * @vma: vm_area_struct holding ptes to be zapped 1704 * @address: starting address of pages to zap 1705 * @size: number of bytes to zap 1706 * 1707 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1708 * 1709 * The entire address range must be fully contained within the vma. 1710 * 1711 */ 1712 void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1713 unsigned long size) 1714 { 1715 if (!range_in_vma(vma, address, address + size) || 1716 !(vma->vm_flags & VM_PFNMAP)) 1717 return; 1718 1719 zap_page_range_single(vma, address, size, NULL); 1720 } 1721 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1722 1723 static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) 1724 { 1725 pgd_t *pgd; 1726 p4d_t *p4d; 1727 pud_t *pud; 1728 pmd_t *pmd; 1729 1730 pgd = pgd_offset(mm, addr); 1731 p4d = p4d_alloc(mm, pgd, addr); 1732 if (!p4d) 1733 return NULL; 1734 pud = pud_alloc(mm, p4d, addr); 1735 if (!pud) 1736 return NULL; 1737 pmd = pmd_alloc(mm, pud, addr); 1738 if (!pmd) 1739 return NULL; 1740 1741 VM_BUG_ON(pmd_trans_huge(*pmd)); 1742 return pmd; 1743 } 1744 1745 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1746 spinlock_t **ptl) 1747 { 1748 pmd_t *pmd = walk_to_pmd(mm, addr); 1749 1750 if (!pmd) 1751 return NULL; 1752 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1753 } 1754 1755 static int validate_page_before_insert(struct page *page) 1756 { 1757 if (PageAnon(page) || PageSlab(page) || page_has_type(page)) 1758 return -EINVAL; 1759 flush_dcache_page(page); 1760 return 0; 1761 } 1762 1763 static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte, 1764 unsigned long addr, struct page *page, pgprot_t prot) 1765 { 1766 if (!pte_none(*pte)) 1767 return -EBUSY; 1768 /* Ok, finally just insert the thing.. */ 1769 get_page(page); 1770 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); 1771 page_add_file_rmap(page, vma, false); 1772 set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot)); 1773 return 0; 1774 } 1775 1776 /* 1777 * This is the old fallback for page remapping. 1778 * 1779 * For historical reasons, it only allows reserved pages. Only 1780 * old drivers should use this, and they needed to mark their 1781 * pages reserved for the old functions anyway. 1782 */ 1783 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1784 struct page *page, pgprot_t prot) 1785 { 1786 int retval; 1787 pte_t *pte; 1788 spinlock_t *ptl; 1789 1790 retval = validate_page_before_insert(page); 1791 if (retval) 1792 goto out; 1793 retval = -ENOMEM; 1794 pte = get_locked_pte(vma->vm_mm, addr, &ptl); 1795 if (!pte) 1796 goto out; 1797 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot); 1798 pte_unmap_unlock(pte, ptl); 1799 out: 1800 return retval; 1801 } 1802 1803 #ifdef pte_index 1804 static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte, 1805 unsigned long addr, struct page *page, pgprot_t prot) 1806 { 1807 int err; 1808 1809 if (!page_count(page)) 1810 return -EINVAL; 1811 err = validate_page_before_insert(page); 1812 if (err) 1813 return err; 1814 return insert_page_into_pte_locked(vma, pte, addr, page, prot); 1815 } 1816 1817 /* insert_pages() amortizes the cost of spinlock operations 1818 * when inserting pages in a loop. Arch *must* define pte_index. 1819 */ 1820 static int insert_pages(struct vm_area_struct *vma, unsigned long addr, 1821 struct page **pages, unsigned long *num, pgprot_t prot) 1822 { 1823 pmd_t *pmd = NULL; 1824 pte_t *start_pte, *pte; 1825 spinlock_t *pte_lock; 1826 struct mm_struct *const mm = vma->vm_mm; 1827 unsigned long curr_page_idx = 0; 1828 unsigned long remaining_pages_total = *num; 1829 unsigned long pages_to_write_in_pmd; 1830 int ret; 1831 more: 1832 ret = -EFAULT; 1833 pmd = walk_to_pmd(mm, addr); 1834 if (!pmd) 1835 goto out; 1836 1837 pages_to_write_in_pmd = min_t(unsigned long, 1838 remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); 1839 1840 /* Allocate the PTE if necessary; takes PMD lock once only. */ 1841 ret = -ENOMEM; 1842 if (pte_alloc(mm, pmd)) 1843 goto out; 1844 1845 while (pages_to_write_in_pmd) { 1846 int pte_idx = 0; 1847 const int batch_size = min_t(int, pages_to_write_in_pmd, 8); 1848 1849 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock); 1850 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { 1851 int err = insert_page_in_batch_locked(vma, pte, 1852 addr, pages[curr_page_idx], prot); 1853 if (unlikely(err)) { 1854 pte_unmap_unlock(start_pte, pte_lock); 1855 ret = err; 1856 remaining_pages_total -= pte_idx; 1857 goto out; 1858 } 1859 addr += PAGE_SIZE; 1860 ++curr_page_idx; 1861 } 1862 pte_unmap_unlock(start_pte, pte_lock); 1863 pages_to_write_in_pmd -= batch_size; 1864 remaining_pages_total -= batch_size; 1865 } 1866 if (remaining_pages_total) 1867 goto more; 1868 ret = 0; 1869 out: 1870 *num = remaining_pages_total; 1871 return ret; 1872 } 1873 #endif /* ifdef pte_index */ 1874 1875 /** 1876 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. 1877 * @vma: user vma to map to 1878 * @addr: target start user address of these pages 1879 * @pages: source kernel pages 1880 * @num: in: number of pages to map. out: number of pages that were *not* 1881 * mapped. (0 means all pages were successfully mapped). 1882 * 1883 * Preferred over vm_insert_page() when inserting multiple pages. 1884 * 1885 * In case of error, we may have mapped a subset of the provided 1886 * pages. It is the caller's responsibility to account for this case. 1887 * 1888 * The same restrictions apply as in vm_insert_page(). 1889 */ 1890 int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, 1891 struct page **pages, unsigned long *num) 1892 { 1893 #ifdef pte_index 1894 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; 1895 1896 if (addr < vma->vm_start || end_addr >= vma->vm_end) 1897 return -EFAULT; 1898 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1899 BUG_ON(mmap_read_trylock(vma->vm_mm)); 1900 BUG_ON(vma->vm_flags & VM_PFNMAP); 1901 vma->vm_flags |= VM_MIXEDMAP; 1902 } 1903 /* Defer page refcount checking till we're about to map that page. */ 1904 return insert_pages(vma, addr, pages, num, vma->vm_page_prot); 1905 #else 1906 unsigned long idx = 0, pgcount = *num; 1907 int err = -EINVAL; 1908 1909 for (; idx < pgcount; ++idx) { 1910 err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]); 1911 if (err) 1912 break; 1913 } 1914 *num = pgcount - idx; 1915 return err; 1916 #endif /* ifdef pte_index */ 1917 } 1918 EXPORT_SYMBOL(vm_insert_pages); 1919 1920 /** 1921 * vm_insert_page - insert single page into user vma 1922 * @vma: user vma to map to 1923 * @addr: target user address of this page 1924 * @page: source kernel page 1925 * 1926 * This allows drivers to insert individual pages they've allocated 1927 * into a user vma. 1928 * 1929 * The page has to be a nice clean _individual_ kernel allocation. 1930 * If you allocate a compound page, you need to have marked it as 1931 * such (__GFP_COMP), or manually just split the page up yourself 1932 * (see split_page()). 1933 * 1934 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1935 * took an arbitrary page protection parameter. This doesn't allow 1936 * that. Your vma protection will have to be set up correctly, which 1937 * means that if you want a shared writable mapping, you'd better 1938 * ask for a shared writable mapping! 1939 * 1940 * The page does not need to be reserved. 1941 * 1942 * Usually this function is called from f_op->mmap() handler 1943 * under mm->mmap_lock write-lock, so it can change vma->vm_flags. 1944 * Caller must set VM_MIXEDMAP on vma if it wants to call this 1945 * function from other places, for example from page-fault handler. 1946 * 1947 * Return: %0 on success, negative error code otherwise. 1948 */ 1949 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1950 struct page *page) 1951 { 1952 if (addr < vma->vm_start || addr >= vma->vm_end) 1953 return -EFAULT; 1954 if (!page_count(page)) 1955 return -EINVAL; 1956 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1957 BUG_ON(mmap_read_trylock(vma->vm_mm)); 1958 BUG_ON(vma->vm_flags & VM_PFNMAP); 1959 vma->vm_flags |= VM_MIXEDMAP; 1960 } 1961 return insert_page(vma, addr, page, vma->vm_page_prot); 1962 } 1963 EXPORT_SYMBOL(vm_insert_page); 1964 1965 /* 1966 * __vm_map_pages - maps range of kernel pages into user vma 1967 * @vma: user vma to map to 1968 * @pages: pointer to array of source kernel pages 1969 * @num: number of pages in page array 1970 * @offset: user's requested vm_pgoff 1971 * 1972 * This allows drivers to map range of kernel pages into a user vma. 1973 * 1974 * Return: 0 on success and error code otherwise. 1975 */ 1976 static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, 1977 unsigned long num, unsigned long offset) 1978 { 1979 unsigned long count = vma_pages(vma); 1980 unsigned long uaddr = vma->vm_start; 1981 int ret, i; 1982 1983 /* Fail if the user requested offset is beyond the end of the object */ 1984 if (offset >= num) 1985 return -ENXIO; 1986 1987 /* Fail if the user requested size exceeds available object size */ 1988 if (count > num - offset) 1989 return -ENXIO; 1990 1991 for (i = 0; i < count; i++) { 1992 ret = vm_insert_page(vma, uaddr, pages[offset + i]); 1993 if (ret < 0) 1994 return ret; 1995 uaddr += PAGE_SIZE; 1996 } 1997 1998 return 0; 1999 } 2000 2001 /** 2002 * vm_map_pages - maps range of kernel pages starts with non zero offset 2003 * @vma: user vma to map to 2004 * @pages: pointer to array of source kernel pages 2005 * @num: number of pages in page array 2006 * 2007 * Maps an object consisting of @num pages, catering for the user's 2008 * requested vm_pgoff 2009 * 2010 * If we fail to insert any page into the vma, the function will return 2011 * immediately leaving any previously inserted pages present. Callers 2012 * from the mmap handler may immediately return the error as their caller 2013 * will destroy the vma, removing any successfully inserted pages. Other 2014 * callers should make their own arrangements for calling unmap_region(). 2015 * 2016 * Context: Process context. Called by mmap handlers. 2017 * Return: 0 on success and error code otherwise. 2018 */ 2019 int vm_map_pages(struct vm_area_struct *vma, struct page **pages, 2020 unsigned long num) 2021 { 2022 return __vm_map_pages(vma, pages, num, vma->vm_pgoff); 2023 } 2024 EXPORT_SYMBOL(vm_map_pages); 2025 2026 /** 2027 * vm_map_pages_zero - map range of kernel pages starts with zero offset 2028 * @vma: user vma to map to 2029 * @pages: pointer to array of source kernel pages 2030 * @num: number of pages in page array 2031 * 2032 * Similar to vm_map_pages(), except that it explicitly sets the offset 2033 * to 0. This function is intended for the drivers that did not consider 2034 * vm_pgoff. 2035 * 2036 * Context: Process context. Called by mmap handlers. 2037 * Return: 0 on success and error code otherwise. 2038 */ 2039 int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, 2040 unsigned long num) 2041 { 2042 return __vm_map_pages(vma, pages, num, 0); 2043 } 2044 EXPORT_SYMBOL(vm_map_pages_zero); 2045 2046 static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2047 pfn_t pfn, pgprot_t prot, bool mkwrite) 2048 { 2049 struct mm_struct *mm = vma->vm_mm; 2050 pte_t *pte, entry; 2051 spinlock_t *ptl; 2052 2053 pte = get_locked_pte(mm, addr, &ptl); 2054 if (!pte) 2055 return VM_FAULT_OOM; 2056 if (!pte_none(*pte)) { 2057 if (mkwrite) { 2058 /* 2059 * For read faults on private mappings the PFN passed 2060 * in may not match the PFN we have mapped if the 2061 * mapped PFN is a writeable COW page. In the mkwrite 2062 * case we are creating a writable PTE for a shared 2063 * mapping and we expect the PFNs to match. If they 2064 * don't match, we are likely racing with block 2065 * allocation and mapping invalidation so just skip the 2066 * update. 2067 */ 2068 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) { 2069 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte))); 2070 goto out_unlock; 2071 } 2072 entry = pte_mkyoung(*pte); 2073 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2074 if (ptep_set_access_flags(vma, addr, pte, entry, 1)) 2075 update_mmu_cache(vma, addr, pte); 2076 } 2077 goto out_unlock; 2078 } 2079 2080 /* Ok, finally just insert the thing.. */ 2081 if (pfn_t_devmap(pfn)) 2082 entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); 2083 else 2084 entry = pte_mkspecial(pfn_t_pte(pfn, prot)); 2085 2086 if (mkwrite) { 2087 entry = pte_mkyoung(entry); 2088 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2089 } 2090 2091 set_pte_at(mm, addr, pte, entry); 2092 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 2093 2094 out_unlock: 2095 pte_unmap_unlock(pte, ptl); 2096 return VM_FAULT_NOPAGE; 2097 } 2098 2099 /** 2100 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot 2101 * @vma: user vma to map to 2102 * @addr: target user address of this page 2103 * @pfn: source kernel pfn 2104 * @pgprot: pgprot flags for the inserted page 2105 * 2106 * This is exactly like vmf_insert_pfn(), except that it allows drivers 2107 * to override pgprot on a per-page basis. 2108 * 2109 * This only makes sense for IO mappings, and it makes no sense for 2110 * COW mappings. In general, using multiple vmas is preferable; 2111 * vmf_insert_pfn_prot should only be used if using multiple VMAs is 2112 * impractical. 2113 * 2114 * See vmf_insert_mixed_prot() for a discussion of the implication of using 2115 * a value of @pgprot different from that of @vma->vm_page_prot. 2116 * 2117 * Context: Process context. May allocate using %GFP_KERNEL. 2118 * Return: vm_fault_t value. 2119 */ 2120 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, 2121 unsigned long pfn, pgprot_t pgprot) 2122 { 2123 /* 2124 * Technically, architectures with pte_special can avoid all these 2125 * restrictions (same for remap_pfn_range). However we would like 2126 * consistency in testing and feature parity among all, so we should 2127 * try to keep these invariants in place for everybody. 2128 */ 2129 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 2130 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 2131 (VM_PFNMAP|VM_MIXEDMAP)); 2132 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 2133 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 2134 2135 if (addr < vma->vm_start || addr >= vma->vm_end) 2136 return VM_FAULT_SIGBUS; 2137 2138 if (!pfn_modify_allowed(pfn, pgprot)) 2139 return VM_FAULT_SIGBUS; 2140 2141 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); 2142 2143 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, 2144 false); 2145 } 2146 EXPORT_SYMBOL(vmf_insert_pfn_prot); 2147 2148 /** 2149 * vmf_insert_pfn - insert single pfn into user vma 2150 * @vma: user vma to map to 2151 * @addr: target user address of this page 2152 * @pfn: source kernel pfn 2153 * 2154 * Similar to vm_insert_page, this allows drivers to insert individual pages 2155 * they've allocated into a user vma. Same comments apply. 2156 * 2157 * This function should only be called from a vm_ops->fault handler, and 2158 * in that case the handler should return the result of this function. 2159 * 2160 * vma cannot be a COW mapping. 2161 * 2162 * As this is called only for pages that do not currently exist, we 2163 * do not need to flush old virtual caches or the TLB. 2164 * 2165 * Context: Process context. May allocate using %GFP_KERNEL. 2166 * Return: vm_fault_t value. 2167 */ 2168 vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2169 unsigned long pfn) 2170 { 2171 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); 2172 } 2173 EXPORT_SYMBOL(vmf_insert_pfn); 2174 2175 static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) 2176 { 2177 /* these checks mirror the abort conditions in vm_normal_page */ 2178 if (vma->vm_flags & VM_MIXEDMAP) 2179 return true; 2180 if (pfn_t_devmap(pfn)) 2181 return true; 2182 if (pfn_t_special(pfn)) 2183 return true; 2184 if (is_zero_pfn(pfn_t_to_pfn(pfn))) 2185 return true; 2186 return false; 2187 } 2188 2189 static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, 2190 unsigned long addr, pfn_t pfn, pgprot_t pgprot, 2191 bool mkwrite) 2192 { 2193 int err; 2194 2195 BUG_ON(!vm_mixed_ok(vma, pfn)); 2196 2197 if (addr < vma->vm_start || addr >= vma->vm_end) 2198 return VM_FAULT_SIGBUS; 2199 2200 track_pfn_insert(vma, &pgprot, pfn); 2201 2202 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot)) 2203 return VM_FAULT_SIGBUS; 2204 2205 /* 2206 * If we don't have pte special, then we have to use the pfn_valid() 2207 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 2208 * refcount the page if pfn_valid is true (hence insert_page rather 2209 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 2210 * without pte special, it would there be refcounted as a normal page. 2211 */ 2212 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && 2213 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { 2214 struct page *page; 2215 2216 /* 2217 * At this point we are committed to insert_page() 2218 * regardless of whether the caller specified flags that 2219 * result in pfn_t_has_page() == false. 2220 */ 2221 page = pfn_to_page(pfn_t_to_pfn(pfn)); 2222 err = insert_page(vma, addr, page, pgprot); 2223 } else { 2224 return insert_pfn(vma, addr, pfn, pgprot, mkwrite); 2225 } 2226 2227 if (err == -ENOMEM) 2228 return VM_FAULT_OOM; 2229 if (err < 0 && err != -EBUSY) 2230 return VM_FAULT_SIGBUS; 2231 2232 return VM_FAULT_NOPAGE; 2233 } 2234 2235 /** 2236 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot 2237 * @vma: user vma to map to 2238 * @addr: target user address of this page 2239 * @pfn: source kernel pfn 2240 * @pgprot: pgprot flags for the inserted page 2241 * 2242 * This is exactly like vmf_insert_mixed(), except that it allows drivers 2243 * to override pgprot on a per-page basis. 2244 * 2245 * Typically this function should be used by drivers to set caching- and 2246 * encryption bits different than those of @vma->vm_page_prot, because 2247 * the caching- or encryption mode may not be known at mmap() time. 2248 * This is ok as long as @vma->vm_page_prot is not used by the core vm 2249 * to set caching and encryption bits for those vmas (except for COW pages). 2250 * This is ensured by core vm only modifying these page table entries using 2251 * functions that don't touch caching- or encryption bits, using pte_modify() 2252 * if needed. (See for example mprotect()). 2253 * Also when new page-table entries are created, this is only done using the 2254 * fault() callback, and never using the value of vma->vm_page_prot, 2255 * except for page-table entries that point to anonymous pages as the result 2256 * of COW. 2257 * 2258 * Context: Process context. May allocate using %GFP_KERNEL. 2259 * Return: vm_fault_t value. 2260 */ 2261 vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr, 2262 pfn_t pfn, pgprot_t pgprot) 2263 { 2264 return __vm_insert_mixed(vma, addr, pfn, pgprot, false); 2265 } 2266 EXPORT_SYMBOL(vmf_insert_mixed_prot); 2267 2268 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 2269 pfn_t pfn) 2270 { 2271 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false); 2272 } 2273 EXPORT_SYMBOL(vmf_insert_mixed); 2274 2275 /* 2276 * If the insertion of PTE failed because someone else already added a 2277 * different entry in the mean time, we treat that as success as we assume 2278 * the same entry was actually inserted. 2279 */ 2280 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, 2281 unsigned long addr, pfn_t pfn) 2282 { 2283 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true); 2284 } 2285 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); 2286 2287 /* 2288 * maps a range of physical memory into the requested pages. the old 2289 * mappings are removed. any references to nonexistent pages results 2290 * in null mappings (currently treated as "copy-on-access") 2291 */ 2292 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 2293 unsigned long addr, unsigned long end, 2294 unsigned long pfn, pgprot_t prot) 2295 { 2296 pte_t *pte, *mapped_pte; 2297 spinlock_t *ptl; 2298 int err = 0; 2299 2300 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 2301 if (!pte) 2302 return -ENOMEM; 2303 arch_enter_lazy_mmu_mode(); 2304 do { 2305 BUG_ON(!pte_none(*pte)); 2306 if (!pfn_modify_allowed(pfn, prot)) { 2307 err = -EACCES; 2308 break; 2309 } 2310 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 2311 pfn++; 2312 } while (pte++, addr += PAGE_SIZE, addr != end); 2313 arch_leave_lazy_mmu_mode(); 2314 pte_unmap_unlock(mapped_pte, ptl); 2315 return err; 2316 } 2317 2318 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 2319 unsigned long addr, unsigned long end, 2320 unsigned long pfn, pgprot_t prot) 2321 { 2322 pmd_t *pmd; 2323 unsigned long next; 2324 int err; 2325 2326 pfn -= addr >> PAGE_SHIFT; 2327 pmd = pmd_alloc(mm, pud, addr); 2328 if (!pmd) 2329 return -ENOMEM; 2330 VM_BUG_ON(pmd_trans_huge(*pmd)); 2331 do { 2332 next = pmd_addr_end(addr, end); 2333 err = remap_pte_range(mm, pmd, addr, next, 2334 pfn + (addr >> PAGE_SHIFT), prot); 2335 if (err) 2336 return err; 2337 } while (pmd++, addr = next, addr != end); 2338 return 0; 2339 } 2340 2341 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, 2342 unsigned long addr, unsigned long end, 2343 unsigned long pfn, pgprot_t prot) 2344 { 2345 pud_t *pud; 2346 unsigned long next; 2347 int err; 2348 2349 pfn -= addr >> PAGE_SHIFT; 2350 pud = pud_alloc(mm, p4d, addr); 2351 if (!pud) 2352 return -ENOMEM; 2353 do { 2354 next = pud_addr_end(addr, end); 2355 err = remap_pmd_range(mm, pud, addr, next, 2356 pfn + (addr >> PAGE_SHIFT), prot); 2357 if (err) 2358 return err; 2359 } while (pud++, addr = next, addr != end); 2360 return 0; 2361 } 2362 2363 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2364 unsigned long addr, unsigned long end, 2365 unsigned long pfn, pgprot_t prot) 2366 { 2367 p4d_t *p4d; 2368 unsigned long next; 2369 int err; 2370 2371 pfn -= addr >> PAGE_SHIFT; 2372 p4d = p4d_alloc(mm, pgd, addr); 2373 if (!p4d) 2374 return -ENOMEM; 2375 do { 2376 next = p4d_addr_end(addr, end); 2377 err = remap_pud_range(mm, p4d, addr, next, 2378 pfn + (addr >> PAGE_SHIFT), prot); 2379 if (err) 2380 return err; 2381 } while (p4d++, addr = next, addr != end); 2382 return 0; 2383 } 2384 2385 /* 2386 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller 2387 * must have pre-validated the caching bits of the pgprot_t. 2388 */ 2389 int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, 2390 unsigned long pfn, unsigned long size, pgprot_t prot) 2391 { 2392 pgd_t *pgd; 2393 unsigned long next; 2394 unsigned long end = addr + PAGE_ALIGN(size); 2395 struct mm_struct *mm = vma->vm_mm; 2396 int err; 2397 2398 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) 2399 return -EINVAL; 2400 2401 /* 2402 * Physically remapped pages are special. Tell the 2403 * rest of the world about it: 2404 * VM_IO tells people not to look at these pages 2405 * (accesses can have side effects). 2406 * VM_PFNMAP tells the core MM that the base pages are just 2407 * raw PFN mappings, and do not have a "struct page" associated 2408 * with them. 2409 * VM_DONTEXPAND 2410 * Disable vma merging and expanding with mremap(). 2411 * VM_DONTDUMP 2412 * Omit vma from core dump, even when VM_IO turned off. 2413 * 2414 * There's a horrible special case to handle copy-on-write 2415 * behaviour that some programs depend on. We mark the "original" 2416 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2417 * See vm_normal_page() for details. 2418 */ 2419 if (is_cow_mapping(vma->vm_flags)) { 2420 if (addr != vma->vm_start || end != vma->vm_end) 2421 return -EINVAL; 2422 vma->vm_pgoff = pfn; 2423 } 2424 2425 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 2426 2427 BUG_ON(addr >= end); 2428 pfn -= addr >> PAGE_SHIFT; 2429 pgd = pgd_offset(mm, addr); 2430 flush_cache_range(vma, addr, end); 2431 do { 2432 next = pgd_addr_end(addr, end); 2433 err = remap_p4d_range(mm, pgd, addr, next, 2434 pfn + (addr >> PAGE_SHIFT), prot); 2435 if (err) 2436 return err; 2437 } while (pgd++, addr = next, addr != end); 2438 2439 return 0; 2440 } 2441 2442 /** 2443 * remap_pfn_range - remap kernel memory to userspace 2444 * @vma: user vma to map to 2445 * @addr: target page aligned user address to start at 2446 * @pfn: page frame number of kernel physical memory address 2447 * @size: size of mapping area 2448 * @prot: page protection flags for this mapping 2449 * 2450 * Note: this is only safe if the mm semaphore is held when called. 2451 * 2452 * Return: %0 on success, negative error code otherwise. 2453 */ 2454 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2455 unsigned long pfn, unsigned long size, pgprot_t prot) 2456 { 2457 int err; 2458 2459 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); 2460 if (err) 2461 return -EINVAL; 2462 2463 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); 2464 if (err) 2465 untrack_pfn(vma, pfn, PAGE_ALIGN(size)); 2466 return err; 2467 } 2468 EXPORT_SYMBOL(remap_pfn_range); 2469 2470 /** 2471 * vm_iomap_memory - remap memory to userspace 2472 * @vma: user vma to map to 2473 * @start: start of the physical memory to be mapped 2474 * @len: size of area 2475 * 2476 * This is a simplified io_remap_pfn_range() for common driver use. The 2477 * driver just needs to give us the physical memory range to be mapped, 2478 * we'll figure out the rest from the vma information. 2479 * 2480 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 2481 * whatever write-combining details or similar. 2482 * 2483 * Return: %0 on success, negative error code otherwise. 2484 */ 2485 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 2486 { 2487 unsigned long vm_len, pfn, pages; 2488 2489 /* Check that the physical memory area passed in looks valid */ 2490 if (start + len < start) 2491 return -EINVAL; 2492 /* 2493 * You *really* shouldn't map things that aren't page-aligned, 2494 * but we've historically allowed it because IO memory might 2495 * just have smaller alignment. 2496 */ 2497 len += start & ~PAGE_MASK; 2498 pfn = start >> PAGE_SHIFT; 2499 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 2500 if (pfn + pages < pfn) 2501 return -EINVAL; 2502 2503 /* We start the mapping 'vm_pgoff' pages into the area */ 2504 if (vma->vm_pgoff > pages) 2505 return -EINVAL; 2506 pfn += vma->vm_pgoff; 2507 pages -= vma->vm_pgoff; 2508 2509 /* Can we fit all of the mapping? */ 2510 vm_len = vma->vm_end - vma->vm_start; 2511 if (vm_len >> PAGE_SHIFT > pages) 2512 return -EINVAL; 2513 2514 /* Ok, let it rip */ 2515 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 2516 } 2517 EXPORT_SYMBOL(vm_iomap_memory); 2518 2519 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2520 unsigned long addr, unsigned long end, 2521 pte_fn_t fn, void *data, bool create, 2522 pgtbl_mod_mask *mask) 2523 { 2524 pte_t *pte, *mapped_pte; 2525 int err = 0; 2526 spinlock_t *ptl; 2527 2528 if (create) { 2529 mapped_pte = pte = (mm == &init_mm) ? 2530 pte_alloc_kernel_track(pmd, addr, mask) : 2531 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2532 if (!pte) 2533 return -ENOMEM; 2534 } else { 2535 mapped_pte = pte = (mm == &init_mm) ? 2536 pte_offset_kernel(pmd, addr) : 2537 pte_offset_map_lock(mm, pmd, addr, &ptl); 2538 } 2539 2540 BUG_ON(pmd_huge(*pmd)); 2541 2542 arch_enter_lazy_mmu_mode(); 2543 2544 if (fn) { 2545 do { 2546 if (create || !pte_none(*pte)) { 2547 err = fn(pte++, addr, data); 2548 if (err) 2549 break; 2550 } 2551 } while (addr += PAGE_SIZE, addr != end); 2552 } 2553 *mask |= PGTBL_PTE_MODIFIED; 2554 2555 arch_leave_lazy_mmu_mode(); 2556 2557 if (mm != &init_mm) 2558 pte_unmap_unlock(mapped_pte, ptl); 2559 return err; 2560 } 2561 2562 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2563 unsigned long addr, unsigned long end, 2564 pte_fn_t fn, void *data, bool create, 2565 pgtbl_mod_mask *mask) 2566 { 2567 pmd_t *pmd; 2568 unsigned long next; 2569 int err = 0; 2570 2571 BUG_ON(pud_huge(*pud)); 2572 2573 if (create) { 2574 pmd = pmd_alloc_track(mm, pud, addr, mask); 2575 if (!pmd) 2576 return -ENOMEM; 2577 } else { 2578 pmd = pmd_offset(pud, addr); 2579 } 2580 do { 2581 next = pmd_addr_end(addr, end); 2582 if (pmd_none(*pmd) && !create) 2583 continue; 2584 if (WARN_ON_ONCE(pmd_leaf(*pmd))) 2585 return -EINVAL; 2586 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { 2587 if (!create) 2588 continue; 2589 pmd_clear_bad(pmd); 2590 } 2591 err = apply_to_pte_range(mm, pmd, addr, next, 2592 fn, data, create, mask); 2593 if (err) 2594 break; 2595 } while (pmd++, addr = next, addr != end); 2596 2597 return err; 2598 } 2599 2600 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, 2601 unsigned long addr, unsigned long end, 2602 pte_fn_t fn, void *data, bool create, 2603 pgtbl_mod_mask *mask) 2604 { 2605 pud_t *pud; 2606 unsigned long next; 2607 int err = 0; 2608 2609 if (create) { 2610 pud = pud_alloc_track(mm, p4d, addr, mask); 2611 if (!pud) 2612 return -ENOMEM; 2613 } else { 2614 pud = pud_offset(p4d, addr); 2615 } 2616 do { 2617 next = pud_addr_end(addr, end); 2618 if (pud_none(*pud) && !create) 2619 continue; 2620 if (WARN_ON_ONCE(pud_leaf(*pud))) 2621 return -EINVAL; 2622 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { 2623 if (!create) 2624 continue; 2625 pud_clear_bad(pud); 2626 } 2627 err = apply_to_pmd_range(mm, pud, addr, next, 2628 fn, data, create, mask); 2629 if (err) 2630 break; 2631 } while (pud++, addr = next, addr != end); 2632 2633 return err; 2634 } 2635 2636 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2637 unsigned long addr, unsigned long end, 2638 pte_fn_t fn, void *data, bool create, 2639 pgtbl_mod_mask *mask) 2640 { 2641 p4d_t *p4d; 2642 unsigned long next; 2643 int err = 0; 2644 2645 if (create) { 2646 p4d = p4d_alloc_track(mm, pgd, addr, mask); 2647 if (!p4d) 2648 return -ENOMEM; 2649 } else { 2650 p4d = p4d_offset(pgd, addr); 2651 } 2652 do { 2653 next = p4d_addr_end(addr, end); 2654 if (p4d_none(*p4d) && !create) 2655 continue; 2656 if (WARN_ON_ONCE(p4d_leaf(*p4d))) 2657 return -EINVAL; 2658 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { 2659 if (!create) 2660 continue; 2661 p4d_clear_bad(p4d); 2662 } 2663 err = apply_to_pud_range(mm, p4d, addr, next, 2664 fn, data, create, mask); 2665 if (err) 2666 break; 2667 } while (p4d++, addr = next, addr != end); 2668 2669 return err; 2670 } 2671 2672 static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2673 unsigned long size, pte_fn_t fn, 2674 void *data, bool create) 2675 { 2676 pgd_t *pgd; 2677 unsigned long start = addr, next; 2678 unsigned long end = addr + size; 2679 pgtbl_mod_mask mask = 0; 2680 int err = 0; 2681 2682 if (WARN_ON(addr >= end)) 2683 return -EINVAL; 2684 2685 pgd = pgd_offset(mm, addr); 2686 do { 2687 next = pgd_addr_end(addr, end); 2688 if (pgd_none(*pgd) && !create) 2689 continue; 2690 if (WARN_ON_ONCE(pgd_leaf(*pgd))) 2691 return -EINVAL; 2692 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { 2693 if (!create) 2694 continue; 2695 pgd_clear_bad(pgd); 2696 } 2697 err = apply_to_p4d_range(mm, pgd, addr, next, 2698 fn, data, create, &mask); 2699 if (err) 2700 break; 2701 } while (pgd++, addr = next, addr != end); 2702 2703 if (mask & ARCH_PAGE_TABLE_SYNC_MASK) 2704 arch_sync_kernel_mappings(start, start + size); 2705 2706 return err; 2707 } 2708 2709 /* 2710 * Scan a region of virtual memory, filling in page tables as necessary 2711 * and calling a provided function on each leaf page table. 2712 */ 2713 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2714 unsigned long size, pte_fn_t fn, void *data) 2715 { 2716 return __apply_to_page_range(mm, addr, size, fn, data, true); 2717 } 2718 EXPORT_SYMBOL_GPL(apply_to_page_range); 2719 2720 /* 2721 * Scan a region of virtual memory, calling a provided function on 2722 * each leaf page table where it exists. 2723 * 2724 * Unlike apply_to_page_range, this does _not_ fill in page tables 2725 * where they are absent. 2726 */ 2727 int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr, 2728 unsigned long size, pte_fn_t fn, void *data) 2729 { 2730 return __apply_to_page_range(mm, addr, size, fn, data, false); 2731 } 2732 EXPORT_SYMBOL_GPL(apply_to_existing_page_range); 2733 2734 /* 2735 * handle_pte_fault chooses page fault handler according to an entry which was 2736 * read non-atomically. Before making any commitment, on those architectures 2737 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched 2738 * parts, do_swap_page must check under lock before unmapping the pte and 2739 * proceeding (but do_wp_page is only called after already making such a check; 2740 * and do_anonymous_page can safely check later on). 2741 */ 2742 static inline int pte_unmap_same(struct vm_fault *vmf) 2743 { 2744 int same = 1; 2745 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION) 2746 if (sizeof(pte_t) > sizeof(unsigned long)) { 2747 spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); 2748 spin_lock(ptl); 2749 same = pte_same(*vmf->pte, vmf->orig_pte); 2750 spin_unlock(ptl); 2751 } 2752 #endif 2753 pte_unmap(vmf->pte); 2754 vmf->pte = NULL; 2755 return same; 2756 } 2757 2758 static inline bool cow_user_page(struct page *dst, struct page *src, 2759 struct vm_fault *vmf) 2760 { 2761 bool ret; 2762 void *kaddr; 2763 void __user *uaddr; 2764 bool locked = false; 2765 struct vm_area_struct *vma = vmf->vma; 2766 struct mm_struct *mm = vma->vm_mm; 2767 unsigned long addr = vmf->address; 2768 2769 if (likely(src)) { 2770 copy_user_highpage(dst, src, addr, vma); 2771 return true; 2772 } 2773 2774 /* 2775 * If the source page was a PFN mapping, we don't have 2776 * a "struct page" for it. We do a best-effort copy by 2777 * just copying from the original user address. If that 2778 * fails, we just zero-fill it. Live with it. 2779 */ 2780 kaddr = kmap_atomic(dst); 2781 uaddr = (void __user *)(addr & PAGE_MASK); 2782 2783 /* 2784 * On architectures with software "accessed" bits, we would 2785 * take a double page fault, so mark it accessed here. 2786 */ 2787 if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) { 2788 pte_t entry; 2789 2790 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); 2791 locked = true; 2792 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { 2793 /* 2794 * Other thread has already handled the fault 2795 * and update local tlb only 2796 */ 2797 update_mmu_tlb(vma, addr, vmf->pte); 2798 ret = false; 2799 goto pte_unlock; 2800 } 2801 2802 entry = pte_mkyoung(vmf->orig_pte); 2803 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0)) 2804 update_mmu_cache(vma, addr, vmf->pte); 2805 } 2806 2807 /* 2808 * This really shouldn't fail, because the page is there 2809 * in the page tables. But it might just be unreadable, 2810 * in which case we just give up and fill the result with 2811 * zeroes. 2812 */ 2813 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { 2814 if (locked) 2815 goto warn; 2816 2817 /* Re-validate under PTL if the page is still mapped */ 2818 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); 2819 locked = true; 2820 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { 2821 /* The PTE changed under us, update local tlb */ 2822 update_mmu_tlb(vma, addr, vmf->pte); 2823 ret = false; 2824 goto pte_unlock; 2825 } 2826 2827 /* 2828 * The same page can be mapped back since last copy attempt. 2829 * Try to copy again under PTL. 2830 */ 2831 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { 2832 /* 2833 * Give a warn in case there can be some obscure 2834 * use-case 2835 */ 2836 warn: 2837 WARN_ON_ONCE(1); 2838 clear_page(kaddr); 2839 } 2840 } 2841 2842 ret = true; 2843 2844 pte_unlock: 2845 if (locked) 2846 pte_unmap_unlock(vmf->pte, vmf->ptl); 2847 kunmap_atomic(kaddr); 2848 flush_dcache_page(dst); 2849 2850 return ret; 2851 } 2852 2853 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) 2854 { 2855 struct file *vm_file = vma->vm_file; 2856 2857 if (vm_file) 2858 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; 2859 2860 /* 2861 * Special mappings (e.g. VDSO) do not have any file so fake 2862 * a default GFP_KERNEL for them. 2863 */ 2864 return GFP_KERNEL; 2865 } 2866 2867 /* 2868 * Notify the address space that the page is about to become writable so that 2869 * it can prohibit this or wait for the page to get into an appropriate state. 2870 * 2871 * We do this without the lock held, so that it can sleep if it needs to. 2872 */ 2873 static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) 2874 { 2875 vm_fault_t ret; 2876 struct page *page = vmf->page; 2877 unsigned int old_flags = vmf->flags; 2878 2879 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2880 2881 if (vmf->vma->vm_file && 2882 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host)) 2883 return VM_FAULT_SIGBUS; 2884 2885 ret = vmf->vma->vm_ops->page_mkwrite(vmf); 2886 /* Restore original flags so that caller is not surprised */ 2887 vmf->flags = old_flags; 2888 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2889 return ret; 2890 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2891 lock_page(page); 2892 if (!page->mapping) { 2893 unlock_page(page); 2894 return 0; /* retry */ 2895 } 2896 ret |= VM_FAULT_LOCKED; 2897 } else 2898 VM_BUG_ON_PAGE(!PageLocked(page), page); 2899 return ret; 2900 } 2901 2902 /* 2903 * Handle dirtying of a page in shared file mapping on a write fault. 2904 * 2905 * The function expects the page to be locked and unlocks it. 2906 */ 2907 static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf) 2908 { 2909 struct vm_area_struct *vma = vmf->vma; 2910 struct address_space *mapping; 2911 struct page *page = vmf->page; 2912 bool dirtied; 2913 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; 2914 2915 dirtied = set_page_dirty(page); 2916 VM_BUG_ON_PAGE(PageAnon(page), page); 2917 /* 2918 * Take a local copy of the address_space - page.mapping may be zeroed 2919 * by truncate after unlock_page(). The address_space itself remains 2920 * pinned by vma->vm_file's reference. We rely on unlock_page()'s 2921 * release semantics to prevent the compiler from undoing this copying. 2922 */ 2923 mapping = page_rmapping(page); 2924 unlock_page(page); 2925 2926 if (!page_mkwrite) 2927 file_update_time(vma->vm_file); 2928 2929 /* 2930 * Throttle page dirtying rate down to writeback speed. 2931 * 2932 * mapping may be NULL here because some device drivers do not 2933 * set page.mapping but still dirty their pages 2934 * 2935 * Drop the mmap_lock before waiting on IO, if we can. The file 2936 * is pinning the mapping, as per above. 2937 */ 2938 if ((dirtied || page_mkwrite) && mapping) { 2939 struct file *fpin; 2940 2941 fpin = maybe_unlock_mmap_for_io(vmf, NULL); 2942 balance_dirty_pages_ratelimited(mapping); 2943 if (fpin) { 2944 fput(fpin); 2945 return VM_FAULT_RETRY; 2946 } 2947 } 2948 2949 return 0; 2950 } 2951 2952 /* 2953 * Handle write page faults for pages that can be reused in the current vma 2954 * 2955 * This can happen either due to the mapping being with the VM_SHARED flag, 2956 * or due to us being the last reference standing to the page. In either 2957 * case, all we need to do here is to mark the page as writable and update 2958 * any related book-keeping. 2959 */ 2960 static inline void wp_page_reuse(struct vm_fault *vmf) 2961 __releases(vmf->ptl) 2962 { 2963 struct vm_area_struct *vma = vmf->vma; 2964 struct page *page = vmf->page; 2965 pte_t entry; 2966 /* 2967 * Clear the pages cpupid information as the existing 2968 * information potentially belongs to a now completely 2969 * unrelated process. 2970 */ 2971 if (page) 2972 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); 2973 2974 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 2975 entry = pte_mkyoung(vmf->orig_pte); 2976 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2977 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) 2978 update_mmu_cache(vma, vmf->address, vmf->pte); 2979 pte_unmap_unlock(vmf->pte, vmf->ptl); 2980 count_vm_event(PGREUSE); 2981 } 2982 2983 /* 2984 * Handle the case of a page which we actually need to copy to a new page. 2985 * 2986 * Called with mmap_lock locked and the old page referenced, but 2987 * without the ptl held. 2988 * 2989 * High level logic flow: 2990 * 2991 * - Allocate a page, copy the content of the old page to the new one. 2992 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. 2993 * - Take the PTL. If the pte changed, bail out and release the allocated page 2994 * - If the pte is still the way we remember it, update the page table and all 2995 * relevant references. This includes dropping the reference the page-table 2996 * held to the old page, as well as updating the rmap. 2997 * - In any case, unlock the PTL and drop the reference we took to the old page. 2998 */ 2999 static vm_fault_t wp_page_copy(struct vm_fault *vmf) 3000 { 3001 struct vm_area_struct *vma = vmf->vma; 3002 struct mm_struct *mm = vma->vm_mm; 3003 struct page *old_page = vmf->page; 3004 struct page *new_page = NULL; 3005 pte_t entry; 3006 int page_copied = 0; 3007 struct mmu_notifier_range range; 3008 3009 if (unlikely(anon_vma_prepare(vma))) 3010 goto oom; 3011 3012 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { 3013 new_page = alloc_zeroed_user_highpage_movable(vma, 3014 vmf->address); 3015 if (!new_page) 3016 goto oom; 3017 } else { 3018 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, 3019 vmf->address); 3020 if (!new_page) 3021 goto oom; 3022 3023 if (!cow_user_page(new_page, old_page, vmf)) { 3024 /* 3025 * COW failed, if the fault was solved by other, 3026 * it's fine. If not, userspace would re-fault on 3027 * the same address and we will handle the fault 3028 * from the second attempt. 3029 */ 3030 put_page(new_page); 3031 if (old_page) 3032 put_page(old_page); 3033 return 0; 3034 } 3035 } 3036 3037 if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL)) 3038 goto oom_free_new; 3039 cgroup_throttle_swaprate(new_page, GFP_KERNEL); 3040 3041 __SetPageUptodate(new_page); 3042 3043 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, 3044 vmf->address & PAGE_MASK, 3045 (vmf->address & PAGE_MASK) + PAGE_SIZE); 3046 mmu_notifier_invalidate_range_start(&range); 3047 3048 /* 3049 * Re-check the pte - we dropped the lock 3050 */ 3051 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); 3052 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { 3053 if (old_page) { 3054 if (!PageAnon(old_page)) { 3055 dec_mm_counter_fast(mm, 3056 mm_counter_file(old_page)); 3057 inc_mm_counter_fast(mm, MM_ANONPAGES); 3058 } 3059 } else { 3060 inc_mm_counter_fast(mm, MM_ANONPAGES); 3061 } 3062 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 3063 entry = mk_pte(new_page, vma->vm_page_prot); 3064 entry = pte_sw_mkyoung(entry); 3065 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3066 3067 /* 3068 * Clear the pte entry and flush it first, before updating the 3069 * pte with the new entry, to keep TLBs on different CPUs in 3070 * sync. This code used to set the new PTE then flush TLBs, but 3071 * that left a window where the new PTE could be loaded into 3072 * some TLBs while the old PTE remains in others. 3073 */ 3074 ptep_clear_flush_notify(vma, vmf->address, vmf->pte); 3075 page_add_new_anon_rmap(new_page, vma, vmf->address, false); 3076 lru_cache_add_inactive_or_unevictable(new_page, vma); 3077 /* 3078 * We call the notify macro here because, when using secondary 3079 * mmu page tables (such as kvm shadow page tables), we want the 3080 * new page to be mapped directly into the secondary page table. 3081 */ 3082 set_pte_at_notify(mm, vmf->address, vmf->pte, entry); 3083 update_mmu_cache(vma, vmf->address, vmf->pte); 3084 if (old_page) { 3085 /* 3086 * Only after switching the pte to the new page may 3087 * we remove the mapcount here. Otherwise another 3088 * process may come and find the rmap count decremented 3089 * before the pte is switched to the new page, and 3090 * "reuse" the old page writing into it while our pte 3091 * here still points into it and can be read by other 3092 * threads. 3093 * 3094 * The critical issue is to order this 3095 * page_remove_rmap with the ptp_clear_flush above. 3096 * Those stores are ordered by (if nothing else,) 3097 * the barrier present in the atomic_add_negative 3098 * in page_remove_rmap. 3099 * 3100 * Then the TLB flush in ptep_clear_flush ensures that 3101 * no process can access the old page before the 3102 * decremented mapcount is visible. And the old page 3103 * cannot be reused until after the decremented 3104 * mapcount is visible. So transitively, TLBs to 3105 * old page will be flushed before it can be reused. 3106 */ 3107 page_remove_rmap(old_page, vma, false); 3108 } 3109 3110 /* Free the old page.. */ 3111 new_page = old_page; 3112 page_copied = 1; 3113 } else { 3114 update_mmu_tlb(vma, vmf->address, vmf->pte); 3115 } 3116 3117 if (new_page) 3118 put_page(new_page); 3119 3120 pte_unmap_unlock(vmf->pte, vmf->ptl); 3121 /* 3122 * No need to double call mmu_notifier->invalidate_range() callback as 3123 * the above ptep_clear_flush_notify() did already call it. 3124 */ 3125 mmu_notifier_invalidate_range_only_end(&range); 3126 if (old_page) { 3127 if (page_copied) 3128 free_swap_cache(old_page); 3129 put_page(old_page); 3130 } 3131 return page_copied ? VM_FAULT_WRITE : 0; 3132 oom_free_new: 3133 put_page(new_page); 3134 oom: 3135 if (old_page) 3136 put_page(old_page); 3137 return VM_FAULT_OOM; 3138 } 3139 3140 /** 3141 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE 3142 * writeable once the page is prepared 3143 * 3144 * @vmf: structure describing the fault 3145 * 3146 * This function handles all that is needed to finish a write page fault in a 3147 * shared mapping due to PTE being read-only once the mapped page is prepared. 3148 * It handles locking of PTE and modifying it. 3149 * 3150 * The function expects the page to be locked or other protection against 3151 * concurrent faults / writeback (such as DAX radix tree locks). 3152 * 3153 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before 3154 * we acquired PTE lock. 3155 */ 3156 vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf) 3157 { 3158 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); 3159 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, 3160 &vmf->ptl); 3161 /* 3162 * We might have raced with another page fault while we released the 3163 * pte_offset_map_lock. 3164 */ 3165 if (!pte_same(*vmf->pte, vmf->orig_pte)) { 3166 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); 3167 pte_unmap_unlock(vmf->pte, vmf->ptl); 3168 return VM_FAULT_NOPAGE; 3169 } 3170 wp_page_reuse(vmf); 3171 return 0; 3172 } 3173 3174 /* 3175 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED 3176 * mapping 3177 */ 3178 static vm_fault_t wp_pfn_shared(struct vm_fault *vmf) 3179 { 3180 struct vm_area_struct *vma = vmf->vma; 3181 3182 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { 3183 vm_fault_t ret; 3184 3185 pte_unmap_unlock(vmf->pte, vmf->ptl); 3186 vmf->flags |= FAULT_FLAG_MKWRITE; 3187 ret = vma->vm_ops->pfn_mkwrite(vmf); 3188 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) 3189 return ret; 3190 return finish_mkwrite_fault(vmf); 3191 } 3192 wp_page_reuse(vmf); 3193 return VM_FAULT_WRITE; 3194 } 3195 3196 static vm_fault_t wp_page_shared(struct vm_fault *vmf) 3197 __releases(vmf->ptl) 3198 { 3199 struct vm_area_struct *vma = vmf->vma; 3200 vm_fault_t ret = VM_FAULT_WRITE; 3201 3202 get_page(vmf->page); 3203 3204 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 3205 vm_fault_t tmp; 3206 3207 pte_unmap_unlock(vmf->pte, vmf->ptl); 3208 tmp = do_page_mkwrite(vmf); 3209 if (unlikely(!tmp || (tmp & 3210 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 3211 put_page(vmf->page); 3212 return tmp; 3213 } 3214 tmp = finish_mkwrite_fault(vmf); 3215 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 3216 unlock_page(vmf->page); 3217 put_page(vmf->page); 3218 return tmp; 3219 } 3220 } else { 3221 wp_page_reuse(vmf); 3222 lock_page(vmf->page); 3223 } 3224 ret |= fault_dirty_shared_page(vmf); 3225 put_page(vmf->page); 3226 3227 return ret; 3228 } 3229 3230 /* 3231 * This routine handles present pages, when users try to write 3232 * to a shared page. It is done by copying the page to a new address 3233 * and decrementing the shared-page counter for the old page. 3234 * 3235 * Note that this routine assumes that the protection checks have been 3236 * done by the caller (the low-level page fault routine in most cases). 3237 * Thus we can safely just mark it writable once we've done any necessary 3238 * COW. 3239 * 3240 * We also mark the page dirty at this point even though the page will 3241 * change only once the write actually happens. This avoids a few races, 3242 * and potentially makes it more efficient. 3243 * 3244 * We enter with non-exclusive mmap_lock (to exclude vma changes, 3245 * but allow concurrent faults), with pte both mapped and locked. 3246 * We return with mmap_lock still held, but pte unmapped and unlocked. 3247 */ 3248 static vm_fault_t do_wp_page(struct vm_fault *vmf) 3249 __releases(vmf->ptl) 3250 { 3251 struct vm_area_struct *vma = vmf->vma; 3252 3253 if (userfaultfd_pte_wp(vma, *vmf->pte)) { 3254 pte_unmap_unlock(vmf->pte, vmf->ptl); 3255 return handle_userfault(vmf, VM_UFFD_WP); 3256 } 3257 3258 /* 3259 * Userfaultfd write-protect can defer flushes. Ensure the TLB 3260 * is flushed in this case before copying. 3261 */ 3262 if (unlikely(userfaultfd_wp(vmf->vma) && 3263 mm_tlb_flush_pending(vmf->vma->vm_mm))) 3264 flush_tlb_page(vmf->vma, vmf->address); 3265 3266 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); 3267 if (!vmf->page) { 3268 /* 3269 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 3270 * VM_PFNMAP VMA. 3271 * 3272 * We should not cow pages in a shared writeable mapping. 3273 * Just mark the pages writable and/or call ops->pfn_mkwrite. 3274 */ 3275 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3276 (VM_WRITE|VM_SHARED)) 3277 return wp_pfn_shared(vmf); 3278 3279 pte_unmap_unlock(vmf->pte, vmf->ptl); 3280 return wp_page_copy(vmf); 3281 } 3282 3283 /* 3284 * Take out anonymous pages first, anonymous shared vmas are 3285 * not dirty accountable. 3286 */ 3287 if (PageAnon(vmf->page)) { 3288 struct page *page = vmf->page; 3289 3290 /* PageKsm() doesn't necessarily raise the page refcount */ 3291 if (PageKsm(page) || page_count(page) != 1) 3292 goto copy; 3293 if (!trylock_page(page)) 3294 goto copy; 3295 if (PageKsm(page) || page_mapcount(page) != 1 || page_count(page) != 1) { 3296 unlock_page(page); 3297 goto copy; 3298 } 3299 /* 3300 * Ok, we've got the only map reference, and the only 3301 * page count reference, and the page is locked, 3302 * it's dark out, and we're wearing sunglasses. Hit it. 3303 */ 3304 unlock_page(page); 3305 wp_page_reuse(vmf); 3306 return VM_FAULT_WRITE; 3307 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 3308 (VM_WRITE|VM_SHARED))) { 3309 return wp_page_shared(vmf); 3310 } 3311 copy: 3312 /* 3313 * Ok, we need to copy. Oh, well.. 3314 */ 3315 get_page(vmf->page); 3316 3317 pte_unmap_unlock(vmf->pte, vmf->ptl); 3318 return wp_page_copy(vmf); 3319 } 3320 3321 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 3322 unsigned long start_addr, unsigned long end_addr, 3323 struct zap_details *details) 3324 { 3325 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 3326 } 3327 3328 static inline void unmap_mapping_range_tree(struct rb_root_cached *root, 3329 pgoff_t first_index, 3330 pgoff_t last_index, 3331 struct zap_details *details) 3332 { 3333 struct vm_area_struct *vma; 3334 pgoff_t vba, vea, zba, zea; 3335 3336 vma_interval_tree_foreach(vma, root, first_index, last_index) { 3337 vba = vma->vm_pgoff; 3338 vea = vba + vma_pages(vma) - 1; 3339 zba = max(first_index, vba); 3340 zea = min(last_index, vea); 3341 3342 unmap_mapping_range_vma(vma, 3343 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 3344 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 3345 details); 3346 } 3347 } 3348 3349 /** 3350 * unmap_mapping_folio() - Unmap single folio from processes. 3351 * @folio: The locked folio to be unmapped. 3352 * 3353 * Unmap this folio from any userspace process which still has it mmaped. 3354 * Typically, for efficiency, the range of nearby pages has already been 3355 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once 3356 * truncation or invalidation holds the lock on a folio, it may find that 3357 * the page has been remapped again: and then uses unmap_mapping_folio() 3358 * to unmap it finally. 3359 */ 3360 void unmap_mapping_folio(struct folio *folio) 3361 { 3362 struct address_space *mapping = folio->mapping; 3363 struct zap_details details = { }; 3364 pgoff_t first_index; 3365 pgoff_t last_index; 3366 3367 VM_BUG_ON(!folio_test_locked(folio)); 3368 3369 first_index = folio->index; 3370 last_index = folio->index + folio_nr_pages(folio) - 1; 3371 3372 details.even_cows = false; 3373 details.single_folio = folio; 3374 3375 i_mmap_lock_write(mapping); 3376 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) 3377 unmap_mapping_range_tree(&mapping->i_mmap, first_index, 3378 last_index, &details); 3379 i_mmap_unlock_write(mapping); 3380 } 3381 3382 /** 3383 * unmap_mapping_pages() - Unmap pages from processes. 3384 * @mapping: The address space containing pages to be unmapped. 3385 * @start: Index of first page to be unmapped. 3386 * @nr: Number of pages to be unmapped. 0 to unmap to end of file. 3387 * @even_cows: Whether to unmap even private COWed pages. 3388 * 3389 * Unmap the pages in this address space from any userspace process which 3390 * has them mmaped. Generally, you want to remove COWed pages as well when 3391 * a file is being truncated, but not when invalidating pages from the page 3392 * cache. 3393 */ 3394 void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, 3395 pgoff_t nr, bool even_cows) 3396 { 3397 struct zap_details details = { }; 3398 pgoff_t first_index = start; 3399 pgoff_t last_index = start + nr - 1; 3400 3401 details.even_cows = even_cows; 3402 if (last_index < first_index) 3403 last_index = ULONG_MAX; 3404 3405 i_mmap_lock_write(mapping); 3406 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) 3407 unmap_mapping_range_tree(&mapping->i_mmap, first_index, 3408 last_index, &details); 3409 i_mmap_unlock_write(mapping); 3410 } 3411 EXPORT_SYMBOL_GPL(unmap_mapping_pages); 3412 3413 /** 3414 * unmap_mapping_range - unmap the portion of all mmaps in the specified 3415 * address_space corresponding to the specified byte range in the underlying 3416 * file. 3417 * 3418 * @mapping: the address space containing mmaps to be unmapped. 3419 * @holebegin: byte in first page to unmap, relative to the start of 3420 * the underlying file. This will be rounded down to a PAGE_SIZE 3421 * boundary. Note that this is different from truncate_pagecache(), which 3422 * must keep the partial page. In contrast, we must get rid of 3423 * partial pages. 3424 * @holelen: size of prospective hole in bytes. This will be rounded 3425 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 3426 * end of the file. 3427 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 3428 * but 0 when invalidating pagecache, don't throw away private data. 3429 */ 3430 void unmap_mapping_range(struct address_space *mapping, 3431 loff_t const holebegin, loff_t const holelen, int even_cows) 3432 { 3433 pgoff_t hba = holebegin >> PAGE_SHIFT; 3434 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 3435 3436 /* Check for overflow. */ 3437 if (sizeof(holelen) > sizeof(hlen)) { 3438 long long holeend = 3439 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 3440 if (holeend & ~(long long)ULONG_MAX) 3441 hlen = ULONG_MAX - hba + 1; 3442 } 3443 3444 unmap_mapping_pages(mapping, hba, hlen, even_cows); 3445 } 3446 EXPORT_SYMBOL(unmap_mapping_range); 3447 3448 /* 3449 * Restore a potential device exclusive pte to a working pte entry 3450 */ 3451 static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) 3452 { 3453 struct page *page = vmf->page; 3454 struct vm_area_struct *vma = vmf->vma; 3455 struct mmu_notifier_range range; 3456 3457 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) 3458 return VM_FAULT_RETRY; 3459 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma, 3460 vma->vm_mm, vmf->address & PAGE_MASK, 3461 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL); 3462 mmu_notifier_invalidate_range_start(&range); 3463 3464 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3465 &vmf->ptl); 3466 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) 3467 restore_exclusive_pte(vma, page, vmf->address, vmf->pte); 3468 3469 pte_unmap_unlock(vmf->pte, vmf->ptl); 3470 unlock_page(page); 3471 3472 mmu_notifier_invalidate_range_end(&range); 3473 return 0; 3474 } 3475 3476 /* 3477 * We enter with non-exclusive mmap_lock (to exclude vma changes, 3478 * but allow concurrent faults), and pte mapped but not yet locked. 3479 * We return with pte unmapped and unlocked. 3480 * 3481 * We return with the mmap_lock locked or unlocked in the same cases 3482 * as does filemap_fault(). 3483 */ 3484 vm_fault_t do_swap_page(struct vm_fault *vmf) 3485 { 3486 struct vm_area_struct *vma = vmf->vma; 3487 struct page *page = NULL, *swapcache; 3488 struct swap_info_struct *si = NULL; 3489 swp_entry_t entry; 3490 pte_t pte; 3491 int locked; 3492 int exclusive = 0; 3493 vm_fault_t ret = 0; 3494 void *shadow = NULL; 3495 3496 if (!pte_unmap_same(vmf)) 3497 goto out; 3498 3499 entry = pte_to_swp_entry(vmf->orig_pte); 3500 if (unlikely(non_swap_entry(entry))) { 3501 if (is_migration_entry(entry)) { 3502 migration_entry_wait(vma->vm_mm, vmf->pmd, 3503 vmf->address); 3504 } else if (is_device_exclusive_entry(entry)) { 3505 vmf->page = pfn_swap_entry_to_page(entry); 3506 ret = remove_device_exclusive_entry(vmf); 3507 } else if (is_device_private_entry(entry)) { 3508 vmf->page = pfn_swap_entry_to_page(entry); 3509 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); 3510 } else if (is_hwpoison_entry(entry)) { 3511 ret = VM_FAULT_HWPOISON; 3512 } else { 3513 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); 3514 ret = VM_FAULT_SIGBUS; 3515 } 3516 goto out; 3517 } 3518 3519 /* Prevent swapoff from happening to us. */ 3520 si = get_swap_device(entry); 3521 if (unlikely(!si)) 3522 goto out; 3523 3524 page = lookup_swap_cache(entry, vma, vmf->address); 3525 swapcache = page; 3526 3527 if (!page) { 3528 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && 3529 __swap_count(entry) == 1) { 3530 /* skip swapcache */ 3531 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, 3532 vmf->address); 3533 if (page) { 3534 __SetPageLocked(page); 3535 __SetPageSwapBacked(page); 3536 3537 if (mem_cgroup_swapin_charge_page(page, 3538 vma->vm_mm, GFP_KERNEL, entry)) { 3539 ret = VM_FAULT_OOM; 3540 goto out_page; 3541 } 3542 mem_cgroup_swapin_uncharge_swap(entry); 3543 3544 shadow = get_shadow_from_swap_cache(entry); 3545 if (shadow) 3546 workingset_refault(page_folio(page), 3547 shadow); 3548 3549 lru_cache_add(page); 3550 3551 /* To provide entry to swap_readpage() */ 3552 set_page_private(page, entry.val); 3553 swap_readpage(page, true); 3554 set_page_private(page, 0); 3555 } 3556 } else { 3557 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, 3558 vmf); 3559 swapcache = page; 3560 } 3561 3562 if (!page) { 3563 /* 3564 * Back out if somebody else faulted in this pte 3565 * while we released the pte lock. 3566 */ 3567 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 3568 vmf->address, &vmf->ptl); 3569 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) 3570 ret = VM_FAULT_OOM; 3571 goto unlock; 3572 } 3573 3574 /* Had to read the page from swap area: Major fault */ 3575 ret = VM_FAULT_MAJOR; 3576 count_vm_event(PGMAJFAULT); 3577 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); 3578 } else if (PageHWPoison(page)) { 3579 /* 3580 * hwpoisoned dirty swapcache pages are kept for killing 3581 * owner processes (which may be unknown at hwpoison time) 3582 */ 3583 ret = VM_FAULT_HWPOISON; 3584 goto out_release; 3585 } 3586 3587 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags); 3588 3589 if (!locked) { 3590 ret |= VM_FAULT_RETRY; 3591 goto out_release; 3592 } 3593 3594 /* 3595 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 3596 * release the swapcache from under us. The page pin, and pte_same 3597 * test below, are not enough to exclude that. Even if it is still 3598 * swapcache, we need to check that the page's swap has not changed. 3599 */ 3600 if (unlikely((!PageSwapCache(page) || 3601 page_private(page) != entry.val)) && swapcache) 3602 goto out_page; 3603 3604 page = ksm_might_need_to_copy(page, vma, vmf->address); 3605 if (unlikely(!page)) { 3606 ret = VM_FAULT_OOM; 3607 page = swapcache; 3608 goto out_page; 3609 } 3610 3611 cgroup_throttle_swaprate(page, GFP_KERNEL); 3612 3613 /* 3614 * Back out if somebody else already faulted in this pte. 3615 */ 3616 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3617 &vmf->ptl); 3618 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) 3619 goto out_nomap; 3620 3621 if (unlikely(!PageUptodate(page))) { 3622 ret = VM_FAULT_SIGBUS; 3623 goto out_nomap; 3624 } 3625 3626 /* 3627 * The page isn't present yet, go ahead with the fault. 3628 * 3629 * Be careful about the sequence of operations here. 3630 * To get its accounting right, reuse_swap_page() must be called 3631 * while the page is counted on swap but not yet in mapcount i.e. 3632 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 3633 * must be called after the swap_free(), or it will never succeed. 3634 */ 3635 3636 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3637 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS); 3638 pte = mk_pte(page, vma->vm_page_prot); 3639 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 3640 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 3641 vmf->flags &= ~FAULT_FLAG_WRITE; 3642 ret |= VM_FAULT_WRITE; 3643 exclusive = RMAP_EXCLUSIVE; 3644 } 3645 flush_icache_page(vma, page); 3646 if (pte_swp_soft_dirty(vmf->orig_pte)) 3647 pte = pte_mksoft_dirty(pte); 3648 if (pte_swp_uffd_wp(vmf->orig_pte)) { 3649 pte = pte_mkuffd_wp(pte); 3650 pte = pte_wrprotect(pte); 3651 } 3652 vmf->orig_pte = pte; 3653 3654 /* ksm created a completely new copy */ 3655 if (unlikely(page != swapcache && swapcache)) { 3656 page_add_new_anon_rmap(page, vma, vmf->address, false); 3657 lru_cache_add_inactive_or_unevictable(page, vma); 3658 } else { 3659 do_page_add_anon_rmap(page, vma, vmf->address, exclusive); 3660 } 3661 3662 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); 3663 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte); 3664 3665 swap_free(entry); 3666 if (mem_cgroup_swap_full(page) || 3667 (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3668 try_to_free_swap(page); 3669 unlock_page(page); 3670 if (page != swapcache && swapcache) { 3671 /* 3672 * Hold the lock to avoid the swap entry to be reused 3673 * until we take the PT lock for the pte_same() check 3674 * (to avoid false positives from pte_same). For 3675 * further safety release the lock after the swap_free 3676 * so that the swap count won't change under a 3677 * parallel locked swapcache. 3678 */ 3679 unlock_page(swapcache); 3680 put_page(swapcache); 3681 } 3682 3683 if (vmf->flags & FAULT_FLAG_WRITE) { 3684 ret |= do_wp_page(vmf); 3685 if (ret & VM_FAULT_ERROR) 3686 ret &= VM_FAULT_ERROR; 3687 goto out; 3688 } 3689 3690 /* No need to invalidate - it was non-present before */ 3691 update_mmu_cache(vma, vmf->address, vmf->pte); 3692 unlock: 3693 pte_unmap_unlock(vmf->pte, vmf->ptl); 3694 out: 3695 if (si) 3696 put_swap_device(si); 3697 return ret; 3698 out_nomap: 3699 pte_unmap_unlock(vmf->pte, vmf->ptl); 3700 out_page: 3701 unlock_page(page); 3702 out_release: 3703 put_page(page); 3704 if (page != swapcache && swapcache) { 3705 unlock_page(swapcache); 3706 put_page(swapcache); 3707 } 3708 if (si) 3709 put_swap_device(si); 3710 return ret; 3711 } 3712 3713 /* 3714 * We enter with non-exclusive mmap_lock (to exclude vma changes, 3715 * but allow concurrent faults), and pte mapped but not yet locked. 3716 * We return with mmap_lock still held, but pte unmapped and unlocked. 3717 */ 3718 static vm_fault_t do_anonymous_page(struct vm_fault *vmf) 3719 { 3720 struct vm_area_struct *vma = vmf->vma; 3721 struct page *page; 3722 vm_fault_t ret = 0; 3723 pte_t entry; 3724 3725 /* File mapping without ->vm_ops ? */ 3726 if (vma->vm_flags & VM_SHARED) 3727 return VM_FAULT_SIGBUS; 3728 3729 /* 3730 * Use pte_alloc() instead of pte_alloc_map(). We can't run 3731 * pte_offset_map() on pmds where a huge pmd might be created 3732 * from a different thread. 3733 * 3734 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when 3735 * parallel threads are excluded by other means. 3736 * 3737 * Here we only have mmap_read_lock(mm). 3738 */ 3739 if (pte_alloc(vma->vm_mm, vmf->pmd)) 3740 return VM_FAULT_OOM; 3741 3742 /* See comment in handle_pte_fault() */ 3743 if (unlikely(pmd_trans_unstable(vmf->pmd))) 3744 return 0; 3745 3746 /* Use the zero-page for reads */ 3747 if (!(vmf->flags & FAULT_FLAG_WRITE) && 3748 !mm_forbids_zeropage(vma->vm_mm)) { 3749 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), 3750 vma->vm_page_prot)); 3751 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 3752 vmf->address, &vmf->ptl); 3753 if (!pte_none(*vmf->pte)) { 3754 update_mmu_tlb(vma, vmf->address, vmf->pte); 3755 goto unlock; 3756 } 3757 ret = check_stable_address_space(vma->vm_mm); 3758 if (ret) 3759 goto unlock; 3760 /* Deliver the page fault to userland, check inside PT lock */ 3761 if (userfaultfd_missing(vma)) { 3762 pte_unmap_unlock(vmf->pte, vmf->ptl); 3763 return handle_userfault(vmf, VM_UFFD_MISSING); 3764 } 3765 goto setpte; 3766 } 3767 3768 /* Allocate our own private page. */ 3769 if (unlikely(anon_vma_prepare(vma))) 3770 goto oom; 3771 page = alloc_zeroed_user_highpage_movable(vma, vmf->address); 3772 if (!page) 3773 goto oom; 3774 3775 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL)) 3776 goto oom_free_page; 3777 cgroup_throttle_swaprate(page, GFP_KERNEL); 3778 3779 /* 3780 * The memory barrier inside __SetPageUptodate makes sure that 3781 * preceding stores to the page contents become visible before 3782 * the set_pte_at() write. 3783 */ 3784 __SetPageUptodate(page); 3785 3786 entry = mk_pte(page, vma->vm_page_prot); 3787 entry = pte_sw_mkyoung(entry); 3788 if (vma->vm_flags & VM_WRITE) 3789 entry = pte_mkwrite(pte_mkdirty(entry)); 3790 3791 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3792 &vmf->ptl); 3793 if (!pte_none(*vmf->pte)) { 3794 update_mmu_cache(vma, vmf->address, vmf->pte); 3795 goto release; 3796 } 3797 3798 ret = check_stable_address_space(vma->vm_mm); 3799 if (ret) 3800 goto release; 3801 3802 /* Deliver the page fault to userland, check inside PT lock */ 3803 if (userfaultfd_missing(vma)) { 3804 pte_unmap_unlock(vmf->pte, vmf->ptl); 3805 put_page(page); 3806 return handle_userfault(vmf, VM_UFFD_MISSING); 3807 } 3808 3809 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3810 page_add_new_anon_rmap(page, vma, vmf->address, false); 3811 lru_cache_add_inactive_or_unevictable(page, vma); 3812 setpte: 3813 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); 3814 3815 /* No need to invalidate - it was non-present before */ 3816 update_mmu_cache(vma, vmf->address, vmf->pte); 3817 unlock: 3818 pte_unmap_unlock(vmf->pte, vmf->ptl); 3819 return ret; 3820 release: 3821 put_page(page); 3822 goto unlock; 3823 oom_free_page: 3824 put_page(page); 3825 oom: 3826 return VM_FAULT_OOM; 3827 } 3828 3829 /* 3830 * The mmap_lock must have been held on entry, and may have been 3831 * released depending on flags and vma->vm_ops->fault() return value. 3832 * See filemap_fault() and __lock_page_retry(). 3833 */ 3834 static vm_fault_t __do_fault(struct vm_fault *vmf) 3835 { 3836 struct vm_area_struct *vma = vmf->vma; 3837 vm_fault_t ret; 3838 3839 /* 3840 * Preallocate pte before we take page_lock because this might lead to 3841 * deadlocks for memcg reclaim which waits for pages under writeback: 3842 * lock_page(A) 3843 * SetPageWriteback(A) 3844 * unlock_page(A) 3845 * lock_page(B) 3846 * lock_page(B) 3847 * pte_alloc_one 3848 * shrink_page_list 3849 * wait_on_page_writeback(A) 3850 * SetPageWriteback(B) 3851 * unlock_page(B) 3852 * # flush A, B to clear the writeback 3853 */ 3854 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) { 3855 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); 3856 if (!vmf->prealloc_pte) 3857 return VM_FAULT_OOM; 3858 } 3859 3860 ret = vma->vm_ops->fault(vmf); 3861 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | 3862 VM_FAULT_DONE_COW))) 3863 return ret; 3864 3865 if (unlikely(PageHWPoison(vmf->page))) { 3866 vm_fault_t poisonret = VM_FAULT_HWPOISON; 3867 if (ret & VM_FAULT_LOCKED) { 3868 /* Retry if a clean page was removed from the cache. */ 3869 if (invalidate_inode_page(vmf->page)) 3870 poisonret = 0; 3871 unlock_page(vmf->page); 3872 } 3873 put_page(vmf->page); 3874 vmf->page = NULL; 3875 return poisonret; 3876 } 3877 3878 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3879 lock_page(vmf->page); 3880 else 3881 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); 3882 3883 return ret; 3884 } 3885 3886 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3887 static void deposit_prealloc_pte(struct vm_fault *vmf) 3888 { 3889 struct vm_area_struct *vma = vmf->vma; 3890 3891 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); 3892 /* 3893 * We are going to consume the prealloc table, 3894 * count that as nr_ptes. 3895 */ 3896 mm_inc_nr_ptes(vma->vm_mm); 3897 vmf->prealloc_pte = NULL; 3898 } 3899 3900 vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) 3901 { 3902 struct vm_area_struct *vma = vmf->vma; 3903 bool write = vmf->flags & FAULT_FLAG_WRITE; 3904 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 3905 pmd_t entry; 3906 int i; 3907 vm_fault_t ret = VM_FAULT_FALLBACK; 3908 3909 if (!transhuge_vma_suitable(vma, haddr)) 3910 return ret; 3911 3912 page = compound_head(page); 3913 if (compound_order(page) != HPAGE_PMD_ORDER) 3914 return ret; 3915 3916 /* 3917 * Just backoff if any subpage of a THP is corrupted otherwise 3918 * the corrupted page may mapped by PMD silently to escape the 3919 * check. This kind of THP just can be PTE mapped. Access to 3920 * the corrupted subpage should trigger SIGBUS as expected. 3921 */ 3922 if (unlikely(PageHasHWPoisoned(page))) 3923 return ret; 3924 3925 /* 3926 * Archs like ppc64 need additional space to store information 3927 * related to pte entry. Use the preallocated table for that. 3928 */ 3929 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { 3930 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); 3931 if (!vmf->prealloc_pte) 3932 return VM_FAULT_OOM; 3933 } 3934 3935 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 3936 if (unlikely(!pmd_none(*vmf->pmd))) 3937 goto out; 3938 3939 for (i = 0; i < HPAGE_PMD_NR; i++) 3940 flush_icache_page(vma, page + i); 3941 3942 entry = mk_huge_pmd(page, vma->vm_page_prot); 3943 if (write) 3944 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 3945 3946 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR); 3947 page_add_file_rmap(page, vma, true); 3948 3949 /* 3950 * deposit and withdraw with pmd lock held 3951 */ 3952 if (arch_needs_pgtable_deposit()) 3953 deposit_prealloc_pte(vmf); 3954 3955 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 3956 3957 update_mmu_cache_pmd(vma, haddr, vmf->pmd); 3958 3959 /* fault is handled */ 3960 ret = 0; 3961 count_vm_event(THP_FILE_MAPPED); 3962 out: 3963 spin_unlock(vmf->ptl); 3964 return ret; 3965 } 3966 #else 3967 vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) 3968 { 3969 return VM_FAULT_FALLBACK; 3970 } 3971 #endif 3972 3973 void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr) 3974 { 3975 struct vm_area_struct *vma = vmf->vma; 3976 bool write = vmf->flags & FAULT_FLAG_WRITE; 3977 bool prefault = vmf->address != addr; 3978 pte_t entry; 3979 3980 flush_icache_page(vma, page); 3981 entry = mk_pte(page, vma->vm_page_prot); 3982 3983 if (prefault && arch_wants_old_prefaulted_pte()) 3984 entry = pte_mkold(entry); 3985 else 3986 entry = pte_sw_mkyoung(entry); 3987 3988 if (write) 3989 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3990 /* copy-on-write page */ 3991 if (write && !(vma->vm_flags & VM_SHARED)) { 3992 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3993 page_add_new_anon_rmap(page, vma, addr, false); 3994 lru_cache_add_inactive_or_unevictable(page, vma); 3995 } else { 3996 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); 3997 page_add_file_rmap(page, vma, false); 3998 } 3999 set_pte_at(vma->vm_mm, addr, vmf->pte, entry); 4000 } 4001 4002 /** 4003 * finish_fault - finish page fault once we have prepared the page to fault 4004 * 4005 * @vmf: structure describing the fault 4006 * 4007 * This function handles all that is needed to finish a page fault once the 4008 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for 4009 * given page, adds reverse page mapping, handles memcg charges and LRU 4010 * addition. 4011 * 4012 * The function expects the page to be locked and on success it consumes a 4013 * reference of a page being mapped (for the PTE which maps it). 4014 * 4015 * Return: %0 on success, %VM_FAULT_ code in case of error. 4016 */ 4017 vm_fault_t finish_fault(struct vm_fault *vmf) 4018 { 4019 struct vm_area_struct *vma = vmf->vma; 4020 struct page *page; 4021 vm_fault_t ret; 4022 4023 /* Did we COW the page? */ 4024 if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 4025 page = vmf->cow_page; 4026 else 4027 page = vmf->page; 4028 4029 /* 4030 * check even for read faults because we might have lost our CoWed 4031 * page 4032 */ 4033 if (!(vma->vm_flags & VM_SHARED)) { 4034 ret = check_stable_address_space(vma->vm_mm); 4035 if (ret) 4036 return ret; 4037 } 4038 4039 if (pmd_none(*vmf->pmd)) { 4040 if (PageTransCompound(page)) { 4041 ret = do_set_pmd(vmf, page); 4042 if (ret != VM_FAULT_FALLBACK) 4043 return ret; 4044 } 4045 4046 if (vmf->prealloc_pte) 4047 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte); 4048 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) 4049 return VM_FAULT_OOM; 4050 } 4051 4052 /* See comment in handle_pte_fault() */ 4053 if (pmd_devmap_trans_unstable(vmf->pmd)) 4054 return 0; 4055 4056 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 4057 vmf->address, &vmf->ptl); 4058 ret = 0; 4059 /* Re-check under ptl */ 4060 if (likely(pte_none(*vmf->pte))) 4061 do_set_pte(vmf, page, vmf->address); 4062 else 4063 ret = VM_FAULT_NOPAGE; 4064 4065 update_mmu_tlb(vma, vmf->address, vmf->pte); 4066 pte_unmap_unlock(vmf->pte, vmf->ptl); 4067 return ret; 4068 } 4069 4070 static unsigned long fault_around_bytes __read_mostly = 4071 rounddown_pow_of_two(65536); 4072 4073 #ifdef CONFIG_DEBUG_FS 4074 static int fault_around_bytes_get(void *data, u64 *val) 4075 { 4076 *val = fault_around_bytes; 4077 return 0; 4078 } 4079 4080 /* 4081 * fault_around_bytes must be rounded down to the nearest page order as it's 4082 * what do_fault_around() expects to see. 4083 */ 4084 static int fault_around_bytes_set(void *data, u64 val) 4085 { 4086 if (val / PAGE_SIZE > PTRS_PER_PTE) 4087 return -EINVAL; 4088 if (val > PAGE_SIZE) 4089 fault_around_bytes = rounddown_pow_of_two(val); 4090 else 4091 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ 4092 return 0; 4093 } 4094 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, 4095 fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); 4096 4097 static int __init fault_around_debugfs(void) 4098 { 4099 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL, 4100 &fault_around_bytes_fops); 4101 return 0; 4102 } 4103 late_initcall(fault_around_debugfs); 4104 #endif 4105 4106 /* 4107 * do_fault_around() tries to map few pages around the fault address. The hope 4108 * is that the pages will be needed soon and this will lower the number of 4109 * faults to handle. 4110 * 4111 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's 4112 * not ready to be mapped: not up-to-date, locked, etc. 4113 * 4114 * This function is called with the page table lock taken. In the split ptlock 4115 * case the page table lock only protects only those entries which belong to 4116 * the page table corresponding to the fault address. 4117 * 4118 * This function doesn't cross the VMA boundaries, in order to call map_pages() 4119 * only once. 4120 * 4121 * fault_around_bytes defines how many bytes we'll try to map. 4122 * do_fault_around() expects it to be set to a power of two less than or equal 4123 * to PTRS_PER_PTE. 4124 * 4125 * The virtual address of the area that we map is naturally aligned to 4126 * fault_around_bytes rounded down to the machine page size 4127 * (and therefore to page order). This way it's easier to guarantee 4128 * that we don't cross page table boundaries. 4129 */ 4130 static vm_fault_t do_fault_around(struct vm_fault *vmf) 4131 { 4132 unsigned long address = vmf->address, nr_pages, mask; 4133 pgoff_t start_pgoff = vmf->pgoff; 4134 pgoff_t end_pgoff; 4135 int off; 4136 4137 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; 4138 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; 4139 4140 address = max(address & mask, vmf->vma->vm_start); 4141 off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 4142 start_pgoff -= off; 4143 4144 /* 4145 * end_pgoff is either the end of the page table, the end of 4146 * the vma or nr_pages from start_pgoff, depending what is nearest. 4147 */ 4148 end_pgoff = start_pgoff - 4149 ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 4150 PTRS_PER_PTE - 1; 4151 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1, 4152 start_pgoff + nr_pages - 1); 4153 4154 if (pmd_none(*vmf->pmd)) { 4155 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); 4156 if (!vmf->prealloc_pte) 4157 return VM_FAULT_OOM; 4158 } 4159 4160 return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); 4161 } 4162 4163 static vm_fault_t do_read_fault(struct vm_fault *vmf) 4164 { 4165 struct vm_area_struct *vma = vmf->vma; 4166 vm_fault_t ret = 0; 4167 4168 /* 4169 * Let's call ->map_pages() first and use ->fault() as fallback 4170 * if page by the offset is not ready to be mapped (cold cache or 4171 * something). 4172 */ 4173 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { 4174 if (likely(!userfaultfd_minor(vmf->vma))) { 4175 ret = do_fault_around(vmf); 4176 if (ret) 4177 return ret; 4178 } 4179 } 4180 4181 ret = __do_fault(vmf); 4182 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 4183 return ret; 4184 4185 ret |= finish_fault(vmf); 4186 unlock_page(vmf->page); 4187 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 4188 put_page(vmf->page); 4189 return ret; 4190 } 4191 4192 static vm_fault_t do_cow_fault(struct vm_fault *vmf) 4193 { 4194 struct vm_area_struct *vma = vmf->vma; 4195 vm_fault_t ret; 4196 4197 if (unlikely(anon_vma_prepare(vma))) 4198 return VM_FAULT_OOM; 4199 4200 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); 4201 if (!vmf->cow_page) 4202 return VM_FAULT_OOM; 4203 4204 if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm, 4205 GFP_KERNEL)) { 4206 put_page(vmf->cow_page); 4207 return VM_FAULT_OOM; 4208 } 4209 cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL); 4210 4211 ret = __do_fault(vmf); 4212 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 4213 goto uncharge_out; 4214 if (ret & VM_FAULT_DONE_COW) 4215 return ret; 4216 4217 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); 4218 __SetPageUptodate(vmf->cow_page); 4219 4220 ret |= finish_fault(vmf); 4221 unlock_page(vmf->page); 4222 put_page(vmf->page); 4223 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 4224 goto uncharge_out; 4225 return ret; 4226 uncharge_out: 4227 put_page(vmf->cow_page); 4228 return ret; 4229 } 4230 4231 static vm_fault_t do_shared_fault(struct vm_fault *vmf) 4232 { 4233 struct vm_area_struct *vma = vmf->vma; 4234 vm_fault_t ret, tmp; 4235 4236 ret = __do_fault(vmf); 4237 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 4238 return ret; 4239 4240 /* 4241 * Check if the backing address space wants to know that the page is 4242 * about to become writable 4243 */ 4244 if (vma->vm_ops->page_mkwrite) { 4245 unlock_page(vmf->page); 4246 tmp = do_page_mkwrite(vmf); 4247 if (unlikely(!tmp || 4248 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 4249 put_page(vmf->page); 4250 return tmp; 4251 } 4252 } 4253 4254 ret |= finish_fault(vmf); 4255 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 4256 VM_FAULT_RETRY))) { 4257 unlock_page(vmf->page); 4258 put_page(vmf->page); 4259 return ret; 4260 } 4261 4262 ret |= fault_dirty_shared_page(vmf); 4263 return ret; 4264 } 4265 4266 /* 4267 * We enter with non-exclusive mmap_lock (to exclude vma changes, 4268 * but allow concurrent faults). 4269 * The mmap_lock may have been released depending on flags and our 4270 * return value. See filemap_fault() and __folio_lock_or_retry(). 4271 * If mmap_lock is released, vma may become invalid (for example 4272 * by other thread calling munmap()). 4273 */ 4274 static vm_fault_t do_fault(struct vm_fault *vmf) 4275 { 4276 struct vm_area_struct *vma = vmf->vma; 4277 struct mm_struct *vm_mm = vma->vm_mm; 4278 vm_fault_t ret; 4279 4280 /* 4281 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND 4282 */ 4283 if (!vma->vm_ops->fault) { 4284 /* 4285 * If we find a migration pmd entry or a none pmd entry, which 4286 * should never happen, return SIGBUS 4287 */ 4288 if (unlikely(!pmd_present(*vmf->pmd))) 4289 ret = VM_FAULT_SIGBUS; 4290 else { 4291 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, 4292 vmf->pmd, 4293 vmf->address, 4294 &vmf->ptl); 4295 /* 4296 * Make sure this is not a temporary clearing of pte 4297 * by holding ptl and checking again. A R/M/W update 4298 * of pte involves: take ptl, clearing the pte so that 4299 * we don't have concurrent modification by hardware 4300 * followed by an update. 4301 */ 4302 if (unlikely(pte_none(*vmf->pte))) 4303 ret = VM_FAULT_SIGBUS; 4304 else 4305 ret = VM_FAULT_NOPAGE; 4306 4307 pte_unmap_unlock(vmf->pte, vmf->ptl); 4308 } 4309 } else if (!(vmf->flags & FAULT_FLAG_WRITE)) 4310 ret = do_read_fault(vmf); 4311 else if (!(vma->vm_flags & VM_SHARED)) 4312 ret = do_cow_fault(vmf); 4313 else 4314 ret = do_shared_fault(vmf); 4315 4316 /* preallocated pagetable is unused: free it */ 4317 if (vmf->prealloc_pte) { 4318 pte_free(vm_mm, vmf->prealloc_pte); 4319 vmf->prealloc_pte = NULL; 4320 } 4321 return ret; 4322 } 4323 4324 int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 4325 unsigned long addr, int page_nid, int *flags) 4326 { 4327 get_page(page); 4328 4329 count_vm_numa_event(NUMA_HINT_FAULTS); 4330 if (page_nid == numa_node_id()) { 4331 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 4332 *flags |= TNF_FAULT_LOCAL; 4333 } 4334 4335 return mpol_misplaced(page, vma, addr); 4336 } 4337 4338 static vm_fault_t do_numa_page(struct vm_fault *vmf) 4339 { 4340 struct vm_area_struct *vma = vmf->vma; 4341 struct page *page = NULL; 4342 int page_nid = NUMA_NO_NODE; 4343 int last_cpupid; 4344 int target_nid; 4345 pte_t pte, old_pte; 4346 bool was_writable = pte_savedwrite(vmf->orig_pte); 4347 int flags = 0; 4348 4349 /* 4350 * The "pte" at this point cannot be used safely without 4351 * validation through pte_unmap_same(). It's of NUMA type but 4352 * the pfn may be screwed if the read is non atomic. 4353 */ 4354 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); 4355 spin_lock(vmf->ptl); 4356 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { 4357 pte_unmap_unlock(vmf->pte, vmf->ptl); 4358 goto out; 4359 } 4360 4361 /* Get the normal PTE */ 4362 old_pte = ptep_get(vmf->pte); 4363 pte = pte_modify(old_pte, vma->vm_page_prot); 4364 4365 page = vm_normal_page(vma, vmf->address, pte); 4366 if (!page) 4367 goto out_map; 4368 4369 /* TODO: handle PTE-mapped THP */ 4370 if (PageCompound(page)) 4371 goto out_map; 4372 4373 /* 4374 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as 4375 * much anyway since they can be in shared cache state. This misses 4376 * the case where a mapping is writable but the process never writes 4377 * to it but pte_write gets cleared during protection updates and 4378 * pte_dirty has unpredictable behaviour between PTE scan updates, 4379 * background writeback, dirty balancing and application behaviour. 4380 */ 4381 if (!was_writable) 4382 flags |= TNF_NO_GROUP; 4383 4384 /* 4385 * Flag if the page is shared between multiple address spaces. This 4386 * is later used when determining whether to group tasks together 4387 */ 4388 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 4389 flags |= TNF_SHARED; 4390 4391 last_cpupid = page_cpupid_last(page); 4392 page_nid = page_to_nid(page); 4393 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid, 4394 &flags); 4395 if (target_nid == NUMA_NO_NODE) { 4396 put_page(page); 4397 goto out_map; 4398 } 4399 pte_unmap_unlock(vmf->pte, vmf->ptl); 4400 4401 /* Migrate to the requested node */ 4402 if (migrate_misplaced_page(page, vma, target_nid)) { 4403 page_nid = target_nid; 4404 flags |= TNF_MIGRATED; 4405 } else { 4406 flags |= TNF_MIGRATE_FAIL; 4407 vmf->pte = pte_offset_map(vmf->pmd, vmf->address); 4408 spin_lock(vmf->ptl); 4409 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { 4410 pte_unmap_unlock(vmf->pte, vmf->ptl); 4411 goto out; 4412 } 4413 goto out_map; 4414 } 4415 4416 out: 4417 if (page_nid != NUMA_NO_NODE) 4418 task_numa_fault(last_cpupid, page_nid, 1, flags); 4419 return 0; 4420 out_map: 4421 /* 4422 * Make it present again, depending on how arch implements 4423 * non-accessible ptes, some can allow access by kernel mode. 4424 */ 4425 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte); 4426 pte = pte_modify(old_pte, vma->vm_page_prot); 4427 pte = pte_mkyoung(pte); 4428 if (was_writable) 4429 pte = pte_mkwrite(pte); 4430 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte); 4431 update_mmu_cache(vma, vmf->address, vmf->pte); 4432 pte_unmap_unlock(vmf->pte, vmf->ptl); 4433 goto out; 4434 } 4435 4436 static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) 4437 { 4438 if (vma_is_anonymous(vmf->vma)) 4439 return do_huge_pmd_anonymous_page(vmf); 4440 if (vmf->vma->vm_ops->huge_fault) 4441 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 4442 return VM_FAULT_FALLBACK; 4443 } 4444 4445 /* `inline' is required to avoid gcc 4.1.2 build error */ 4446 static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) 4447 { 4448 if (vma_is_anonymous(vmf->vma)) { 4449 if (userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd)) 4450 return handle_userfault(vmf, VM_UFFD_WP); 4451 return do_huge_pmd_wp_page(vmf); 4452 } 4453 if (vmf->vma->vm_ops->huge_fault) { 4454 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 4455 4456 if (!(ret & VM_FAULT_FALLBACK)) 4457 return ret; 4458 } 4459 4460 /* COW or write-notify handled on pte level: split pmd. */ 4461 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL); 4462 4463 return VM_FAULT_FALLBACK; 4464 } 4465 4466 static vm_fault_t create_huge_pud(struct vm_fault *vmf) 4467 { 4468 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ 4469 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) 4470 /* No support for anonymous transparent PUD pages yet */ 4471 if (vma_is_anonymous(vmf->vma)) 4472 goto split; 4473 if (vmf->vma->vm_ops->huge_fault) { 4474 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 4475 4476 if (!(ret & VM_FAULT_FALLBACK)) 4477 return ret; 4478 } 4479 split: 4480 /* COW or write-notify not handled on PUD level: split pud.*/ 4481 __split_huge_pud(vmf->vma, vmf->pud, vmf->address); 4482 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 4483 return VM_FAULT_FALLBACK; 4484 } 4485 4486 static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) 4487 { 4488 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 4489 /* No support for anonymous transparent PUD pages yet */ 4490 if (vma_is_anonymous(vmf->vma)) 4491 return VM_FAULT_FALLBACK; 4492 if (vmf->vma->vm_ops->huge_fault) 4493 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 4494 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 4495 return VM_FAULT_FALLBACK; 4496 } 4497 4498 /* 4499 * These routines also need to handle stuff like marking pages dirty 4500 * and/or accessed for architectures that don't do it in hardware (most 4501 * RISC architectures). The early dirtying is also good on the i386. 4502 * 4503 * There is also a hook called "update_mmu_cache()" that architectures 4504 * with external mmu caches can use to update those (ie the Sparc or 4505 * PowerPC hashed page tables that act as extended TLBs). 4506 * 4507 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow 4508 * concurrent faults). 4509 * 4510 * The mmap_lock may have been released depending on flags and our return value. 4511 * See filemap_fault() and __folio_lock_or_retry(). 4512 */ 4513 static vm_fault_t handle_pte_fault(struct vm_fault *vmf) 4514 { 4515 pte_t entry; 4516 4517 if (unlikely(pmd_none(*vmf->pmd))) { 4518 /* 4519 * Leave __pte_alloc() until later: because vm_ops->fault may 4520 * want to allocate huge page, and if we expose page table 4521 * for an instant, it will be difficult to retract from 4522 * concurrent faults and from rmap lookups. 4523 */ 4524 vmf->pte = NULL; 4525 } else { 4526 /* 4527 * If a huge pmd materialized under us just retry later. Use 4528 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead 4529 * of pmd_trans_huge() to ensure the pmd didn't become 4530 * pmd_trans_huge under us and then back to pmd_none, as a 4531 * result of MADV_DONTNEED running immediately after a huge pmd 4532 * fault in a different thread of this mm, in turn leading to a 4533 * misleading pmd_trans_huge() retval. All we have to ensure is 4534 * that it is a regular pmd that we can walk with 4535 * pte_offset_map() and we can do that through an atomic read 4536 * in C, which is what pmd_trans_unstable() provides. 4537 */ 4538 if (pmd_devmap_trans_unstable(vmf->pmd)) 4539 return 0; 4540 /* 4541 * A regular pmd is established and it can't morph into a huge 4542 * pmd from under us anymore at this point because we hold the 4543 * mmap_lock read mode and khugepaged takes it in write mode. 4544 * So now it's safe to run pte_offset_map(). 4545 */ 4546 vmf->pte = pte_offset_map(vmf->pmd, vmf->address); 4547 vmf->orig_pte = *vmf->pte; 4548 4549 /* 4550 * some architectures can have larger ptes than wordsize, 4551 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and 4552 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic 4553 * accesses. The code below just needs a consistent view 4554 * for the ifs and we later double check anyway with the 4555 * ptl lock held. So here a barrier will do. 4556 */ 4557 barrier(); 4558 if (pte_none(vmf->orig_pte)) { 4559 pte_unmap(vmf->pte); 4560 vmf->pte = NULL; 4561 } 4562 } 4563 4564 if (!vmf->pte) { 4565 if (vma_is_anonymous(vmf->vma)) 4566 return do_anonymous_page(vmf); 4567 else 4568 return do_fault(vmf); 4569 } 4570 4571 if (!pte_present(vmf->orig_pte)) 4572 return do_swap_page(vmf); 4573 4574 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) 4575 return do_numa_page(vmf); 4576 4577 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); 4578 spin_lock(vmf->ptl); 4579 entry = vmf->orig_pte; 4580 if (unlikely(!pte_same(*vmf->pte, entry))) { 4581 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); 4582 goto unlock; 4583 } 4584 if (vmf->flags & FAULT_FLAG_WRITE) { 4585 if (!pte_write(entry)) 4586 return do_wp_page(vmf); 4587 entry = pte_mkdirty(entry); 4588 } 4589 entry = pte_mkyoung(entry); 4590 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, 4591 vmf->flags & FAULT_FLAG_WRITE)) { 4592 update_mmu_cache(vmf->vma, vmf->address, vmf->pte); 4593 } else { 4594 /* Skip spurious TLB flush for retried page fault */ 4595 if (vmf->flags & FAULT_FLAG_TRIED) 4596 goto unlock; 4597 /* 4598 * This is needed only for protection faults but the arch code 4599 * is not yet telling us if this is a protection fault or not. 4600 * This still avoids useless tlb flushes for .text page faults 4601 * with threads. 4602 */ 4603 if (vmf->flags & FAULT_FLAG_WRITE) 4604 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address); 4605 } 4606 unlock: 4607 pte_unmap_unlock(vmf->pte, vmf->ptl); 4608 return 0; 4609 } 4610 4611 /* 4612 * By the time we get here, we already hold the mm semaphore 4613 * 4614 * The mmap_lock may have been released depending on flags and our 4615 * return value. See filemap_fault() and __folio_lock_or_retry(). 4616 */ 4617 static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, 4618 unsigned long address, unsigned int flags) 4619 { 4620 struct vm_fault vmf = { 4621 .vma = vma, 4622 .address = address & PAGE_MASK, 4623 .real_address = address, 4624 .flags = flags, 4625 .pgoff = linear_page_index(vma, address), 4626 .gfp_mask = __get_fault_gfp_mask(vma), 4627 }; 4628 unsigned int dirty = flags & FAULT_FLAG_WRITE; 4629 struct mm_struct *mm = vma->vm_mm; 4630 pgd_t *pgd; 4631 p4d_t *p4d; 4632 vm_fault_t ret; 4633 4634 pgd = pgd_offset(mm, address); 4635 p4d = p4d_alloc(mm, pgd, address); 4636 if (!p4d) 4637 return VM_FAULT_OOM; 4638 4639 vmf.pud = pud_alloc(mm, p4d, address); 4640 if (!vmf.pud) 4641 return VM_FAULT_OOM; 4642 retry_pud: 4643 if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) { 4644 ret = create_huge_pud(&vmf); 4645 if (!(ret & VM_FAULT_FALLBACK)) 4646 return ret; 4647 } else { 4648 pud_t orig_pud = *vmf.pud; 4649 4650 barrier(); 4651 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { 4652 4653 /* NUMA case for anonymous PUDs would go here */ 4654 4655 if (dirty && !pud_write(orig_pud)) { 4656 ret = wp_huge_pud(&vmf, orig_pud); 4657 if (!(ret & VM_FAULT_FALLBACK)) 4658 return ret; 4659 } else { 4660 huge_pud_set_accessed(&vmf, orig_pud); 4661 return 0; 4662 } 4663 } 4664 } 4665 4666 vmf.pmd = pmd_alloc(mm, vmf.pud, address); 4667 if (!vmf.pmd) 4668 return VM_FAULT_OOM; 4669 4670 /* Huge pud page fault raced with pmd_alloc? */ 4671 if (pud_trans_unstable(vmf.pud)) 4672 goto retry_pud; 4673 4674 if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) { 4675 ret = create_huge_pmd(&vmf); 4676 if (!(ret & VM_FAULT_FALLBACK)) 4677 return ret; 4678 } else { 4679 vmf.orig_pmd = *vmf.pmd; 4680 4681 barrier(); 4682 if (unlikely(is_swap_pmd(vmf.orig_pmd))) { 4683 VM_BUG_ON(thp_migration_supported() && 4684 !is_pmd_migration_entry(vmf.orig_pmd)); 4685 if (is_pmd_migration_entry(vmf.orig_pmd)) 4686 pmd_migration_entry_wait(mm, vmf.pmd); 4687 return 0; 4688 } 4689 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) { 4690 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma)) 4691 return do_huge_pmd_numa_page(&vmf); 4692 4693 if (dirty && !pmd_write(vmf.orig_pmd)) { 4694 ret = wp_huge_pmd(&vmf); 4695 if (!(ret & VM_FAULT_FALLBACK)) 4696 return ret; 4697 } else { 4698 huge_pmd_set_accessed(&vmf); 4699 return 0; 4700 } 4701 } 4702 } 4703 4704 return handle_pte_fault(&vmf); 4705 } 4706 4707 /** 4708 * mm_account_fault - Do page fault accounting 4709 * 4710 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting 4711 * of perf event counters, but we'll still do the per-task accounting to 4712 * the task who triggered this page fault. 4713 * @address: the faulted address. 4714 * @flags: the fault flags. 4715 * @ret: the fault retcode. 4716 * 4717 * This will take care of most of the page fault accounting. Meanwhile, it 4718 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter 4719 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should 4720 * still be in per-arch page fault handlers at the entry of page fault. 4721 */ 4722 static inline void mm_account_fault(struct pt_regs *regs, 4723 unsigned long address, unsigned int flags, 4724 vm_fault_t ret) 4725 { 4726 bool major; 4727 4728 /* 4729 * We don't do accounting for some specific faults: 4730 * 4731 * - Unsuccessful faults (e.g. when the address wasn't valid). That 4732 * includes arch_vma_access_permitted() failing before reaching here. 4733 * So this is not a "this many hardware page faults" counter. We 4734 * should use the hw profiling for that. 4735 * 4736 * - Incomplete faults (VM_FAULT_RETRY). They will only be counted 4737 * once they're completed. 4738 */ 4739 if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY)) 4740 return; 4741 4742 /* 4743 * We define the fault as a major fault when the final successful fault 4744 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't 4745 * handle it immediately previously). 4746 */ 4747 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED); 4748 4749 if (major) 4750 current->maj_flt++; 4751 else 4752 current->min_flt++; 4753 4754 /* 4755 * If the fault is done for GUP, regs will be NULL. We only do the 4756 * accounting for the per thread fault counters who triggered the 4757 * fault, and we skip the perf event updates. 4758 */ 4759 if (!regs) 4760 return; 4761 4762 if (major) 4763 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); 4764 else 4765 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); 4766 } 4767 4768 /* 4769 * By the time we get here, we already hold the mm semaphore 4770 * 4771 * The mmap_lock may have been released depending on flags and our 4772 * return value. See filemap_fault() and __folio_lock_or_retry(). 4773 */ 4774 vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 4775 unsigned int flags, struct pt_regs *regs) 4776 { 4777 vm_fault_t ret; 4778 4779 __set_current_state(TASK_RUNNING); 4780 4781 count_vm_event(PGFAULT); 4782 count_memcg_event_mm(vma->vm_mm, PGFAULT); 4783 4784 /* do counter updates before entering really critical section. */ 4785 check_sync_rss_stat(current); 4786 4787 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, 4788 flags & FAULT_FLAG_INSTRUCTION, 4789 flags & FAULT_FLAG_REMOTE)) 4790 return VM_FAULT_SIGSEGV; 4791 4792 /* 4793 * Enable the memcg OOM handling for faults triggered in user 4794 * space. Kernel faults are handled more gracefully. 4795 */ 4796 if (flags & FAULT_FLAG_USER) 4797 mem_cgroup_enter_user_fault(); 4798 4799 if (unlikely(is_vm_hugetlb_page(vma))) 4800 ret = hugetlb_fault(vma->vm_mm, vma, address, flags); 4801 else 4802 ret = __handle_mm_fault(vma, address, flags); 4803 4804 if (flags & FAULT_FLAG_USER) { 4805 mem_cgroup_exit_user_fault(); 4806 /* 4807 * The task may have entered a memcg OOM situation but 4808 * if the allocation error was handled gracefully (no 4809 * VM_FAULT_OOM), there is no need to kill anything. 4810 * Just clean up the OOM state peacefully. 4811 */ 4812 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 4813 mem_cgroup_oom_synchronize(false); 4814 } 4815 4816 mm_account_fault(regs, address, flags, ret); 4817 4818 return ret; 4819 } 4820 EXPORT_SYMBOL_GPL(handle_mm_fault); 4821 4822 #ifndef __PAGETABLE_P4D_FOLDED 4823 /* 4824 * Allocate p4d page table. 4825 * We've already handled the fast-path in-line. 4826 */ 4827 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 4828 { 4829 p4d_t *new = p4d_alloc_one(mm, address); 4830 if (!new) 4831 return -ENOMEM; 4832 4833 spin_lock(&mm->page_table_lock); 4834 if (pgd_present(*pgd)) { /* Another has populated it */ 4835 p4d_free(mm, new); 4836 } else { 4837 smp_wmb(); /* See comment in pmd_install() */ 4838 pgd_populate(mm, pgd, new); 4839 } 4840 spin_unlock(&mm->page_table_lock); 4841 return 0; 4842 } 4843 #endif /* __PAGETABLE_P4D_FOLDED */ 4844 4845 #ifndef __PAGETABLE_PUD_FOLDED 4846 /* 4847 * Allocate page upper directory. 4848 * We've already handled the fast-path in-line. 4849 */ 4850 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) 4851 { 4852 pud_t *new = pud_alloc_one(mm, address); 4853 if (!new) 4854 return -ENOMEM; 4855 4856 spin_lock(&mm->page_table_lock); 4857 if (!p4d_present(*p4d)) { 4858 mm_inc_nr_puds(mm); 4859 smp_wmb(); /* See comment in pmd_install() */ 4860 p4d_populate(mm, p4d, new); 4861 } else /* Another has populated it */ 4862 pud_free(mm, new); 4863 spin_unlock(&mm->page_table_lock); 4864 return 0; 4865 } 4866 #endif /* __PAGETABLE_PUD_FOLDED */ 4867 4868 #ifndef __PAGETABLE_PMD_FOLDED 4869 /* 4870 * Allocate page middle directory. 4871 * We've already handled the fast-path in-line. 4872 */ 4873 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 4874 { 4875 spinlock_t *ptl; 4876 pmd_t *new = pmd_alloc_one(mm, address); 4877 if (!new) 4878 return -ENOMEM; 4879 4880 ptl = pud_lock(mm, pud); 4881 if (!pud_present(*pud)) { 4882 mm_inc_nr_pmds(mm); 4883 smp_wmb(); /* See comment in pmd_install() */ 4884 pud_populate(mm, pud, new); 4885 } else { /* Another has populated it */ 4886 pmd_free(mm, new); 4887 } 4888 spin_unlock(ptl); 4889 return 0; 4890 } 4891 #endif /* __PAGETABLE_PMD_FOLDED */ 4892 4893 int follow_invalidate_pte(struct mm_struct *mm, unsigned long address, 4894 struct mmu_notifier_range *range, pte_t **ptepp, 4895 pmd_t **pmdpp, spinlock_t **ptlp) 4896 { 4897 pgd_t *pgd; 4898 p4d_t *p4d; 4899 pud_t *pud; 4900 pmd_t *pmd; 4901 pte_t *ptep; 4902 4903 pgd = pgd_offset(mm, address); 4904 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 4905 goto out; 4906 4907 p4d = p4d_offset(pgd, address); 4908 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d))) 4909 goto out; 4910 4911 pud = pud_offset(p4d, address); 4912 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 4913 goto out; 4914 4915 pmd = pmd_offset(pud, address); 4916 VM_BUG_ON(pmd_trans_huge(*pmd)); 4917 4918 if (pmd_huge(*pmd)) { 4919 if (!pmdpp) 4920 goto out; 4921 4922 if (range) { 4923 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, 4924 NULL, mm, address & PMD_MASK, 4925 (address & PMD_MASK) + PMD_SIZE); 4926 mmu_notifier_invalidate_range_start(range); 4927 } 4928 *ptlp = pmd_lock(mm, pmd); 4929 if (pmd_huge(*pmd)) { 4930 *pmdpp = pmd; 4931 return 0; 4932 } 4933 spin_unlock(*ptlp); 4934 if (range) 4935 mmu_notifier_invalidate_range_end(range); 4936 } 4937 4938 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 4939 goto out; 4940 4941 if (range) { 4942 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm, 4943 address & PAGE_MASK, 4944 (address & PAGE_MASK) + PAGE_SIZE); 4945 mmu_notifier_invalidate_range_start(range); 4946 } 4947 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 4948 if (!pte_present(*ptep)) 4949 goto unlock; 4950 *ptepp = ptep; 4951 return 0; 4952 unlock: 4953 pte_unmap_unlock(ptep, *ptlp); 4954 if (range) 4955 mmu_notifier_invalidate_range_end(range); 4956 out: 4957 return -EINVAL; 4958 } 4959 4960 /** 4961 * follow_pte - look up PTE at a user virtual address 4962 * @mm: the mm_struct of the target address space 4963 * @address: user virtual address 4964 * @ptepp: location to store found PTE 4965 * @ptlp: location to store the lock for the PTE 4966 * 4967 * On a successful return, the pointer to the PTE is stored in @ptepp; 4968 * the corresponding lock is taken and its location is stored in @ptlp. 4969 * The contents of the PTE are only stable until @ptlp is released; 4970 * any further use, if any, must be protected against invalidation 4971 * with MMU notifiers. 4972 * 4973 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore 4974 * should be taken for read. 4975 * 4976 * KVM uses this function. While it is arguably less bad than ``follow_pfn``, 4977 * it is not a good general-purpose API. 4978 * 4979 * Return: zero on success, -ve otherwise. 4980 */ 4981 int follow_pte(struct mm_struct *mm, unsigned long address, 4982 pte_t **ptepp, spinlock_t **ptlp) 4983 { 4984 return follow_invalidate_pte(mm, address, NULL, ptepp, NULL, ptlp); 4985 } 4986 EXPORT_SYMBOL_GPL(follow_pte); 4987 4988 /** 4989 * follow_pfn - look up PFN at a user virtual address 4990 * @vma: memory mapping 4991 * @address: user virtual address 4992 * @pfn: location to store found PFN 4993 * 4994 * Only IO mappings and raw PFN mappings are allowed. 4995 * 4996 * This function does not allow the caller to read the permissions 4997 * of the PTE. Do not use it. 4998 * 4999 * Return: zero and the pfn at @pfn on success, -ve otherwise. 5000 */ 5001 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 5002 unsigned long *pfn) 5003 { 5004 int ret = -EINVAL; 5005 spinlock_t *ptl; 5006 pte_t *ptep; 5007 5008 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 5009 return ret; 5010 5011 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 5012 if (ret) 5013 return ret; 5014 *pfn = pte_pfn(*ptep); 5015 pte_unmap_unlock(ptep, ptl); 5016 return 0; 5017 } 5018 EXPORT_SYMBOL(follow_pfn); 5019 5020 #ifdef CONFIG_HAVE_IOREMAP_PROT 5021 int follow_phys(struct vm_area_struct *vma, 5022 unsigned long address, unsigned int flags, 5023 unsigned long *prot, resource_size_t *phys) 5024 { 5025 int ret = -EINVAL; 5026 pte_t *ptep, pte; 5027 spinlock_t *ptl; 5028 5029 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 5030 goto out; 5031 5032 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 5033 goto out; 5034 pte = *ptep; 5035 5036 if ((flags & FOLL_WRITE) && !pte_write(pte)) 5037 goto unlock; 5038 5039 *prot = pgprot_val(pte_pgprot(pte)); 5040 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 5041 5042 ret = 0; 5043 unlock: 5044 pte_unmap_unlock(ptep, ptl); 5045 out: 5046 return ret; 5047 } 5048 5049 /** 5050 * generic_access_phys - generic implementation for iomem mmap access 5051 * @vma: the vma to access 5052 * @addr: userspace address, not relative offset within @vma 5053 * @buf: buffer to read/write 5054 * @len: length of transfer 5055 * @write: set to FOLL_WRITE when writing, otherwise reading 5056 * 5057 * This is a generic implementation for &vm_operations_struct.access for an 5058 * iomem mapping. This callback is used by access_process_vm() when the @vma is 5059 * not page based. 5060 */ 5061 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 5062 void *buf, int len, int write) 5063 { 5064 resource_size_t phys_addr; 5065 unsigned long prot = 0; 5066 void __iomem *maddr; 5067 pte_t *ptep, pte; 5068 spinlock_t *ptl; 5069 int offset = offset_in_page(addr); 5070 int ret = -EINVAL; 5071 5072 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 5073 return -EINVAL; 5074 5075 retry: 5076 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) 5077 return -EINVAL; 5078 pte = *ptep; 5079 pte_unmap_unlock(ptep, ptl); 5080 5081 prot = pgprot_val(pte_pgprot(pte)); 5082 phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 5083 5084 if ((write & FOLL_WRITE) && !pte_write(pte)) 5085 return -EINVAL; 5086 5087 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); 5088 if (!maddr) 5089 return -ENOMEM; 5090 5091 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) 5092 goto out_unmap; 5093 5094 if (!pte_same(pte, *ptep)) { 5095 pte_unmap_unlock(ptep, ptl); 5096 iounmap(maddr); 5097 5098 goto retry; 5099 } 5100 5101 if (write) 5102 memcpy_toio(maddr + offset, buf, len); 5103 else 5104 memcpy_fromio(buf, maddr + offset, len); 5105 ret = len; 5106 pte_unmap_unlock(ptep, ptl); 5107 out_unmap: 5108 iounmap(maddr); 5109 5110 return ret; 5111 } 5112 EXPORT_SYMBOL_GPL(generic_access_phys); 5113 #endif 5114 5115 /* 5116 * Access another process' address space as given in mm. 5117 */ 5118 int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, 5119 int len, unsigned int gup_flags) 5120 { 5121 struct vm_area_struct *vma; 5122 void *old_buf = buf; 5123 int write = gup_flags & FOLL_WRITE; 5124 5125 if (mmap_read_lock_killable(mm)) 5126 return 0; 5127 5128 /* ignore errors, just check how much was successfully transferred */ 5129 while (len) { 5130 int bytes, ret, offset; 5131 void *maddr; 5132 struct page *page = NULL; 5133 5134 ret = get_user_pages_remote(mm, addr, 1, 5135 gup_flags, &page, &vma, NULL); 5136 if (ret <= 0) { 5137 #ifndef CONFIG_HAVE_IOREMAP_PROT 5138 break; 5139 #else 5140 /* 5141 * Check if this is a VM_IO | VM_PFNMAP VMA, which 5142 * we can access using slightly different code. 5143 */ 5144 vma = vma_lookup(mm, addr); 5145 if (!vma) 5146 break; 5147 if (vma->vm_ops && vma->vm_ops->access) 5148 ret = vma->vm_ops->access(vma, addr, buf, 5149 len, write); 5150 if (ret <= 0) 5151 break; 5152 bytes = ret; 5153 #endif 5154 } else { 5155 bytes = len; 5156 offset = addr & (PAGE_SIZE-1); 5157 if (bytes > PAGE_SIZE-offset) 5158 bytes = PAGE_SIZE-offset; 5159 5160 maddr = kmap(page); 5161 if (write) { 5162 copy_to_user_page(vma, page, addr, 5163 maddr + offset, buf, bytes); 5164 set_page_dirty_lock(page); 5165 } else { 5166 copy_from_user_page(vma, page, addr, 5167 buf, maddr + offset, bytes); 5168 } 5169 kunmap(page); 5170 put_page(page); 5171 } 5172 len -= bytes; 5173 buf += bytes; 5174 addr += bytes; 5175 } 5176 mmap_read_unlock(mm); 5177 5178 return buf - old_buf; 5179 } 5180 5181 /** 5182 * access_remote_vm - access another process' address space 5183 * @mm: the mm_struct of the target address space 5184 * @addr: start address to access 5185 * @buf: source or destination buffer 5186 * @len: number of bytes to transfer 5187 * @gup_flags: flags modifying lookup behaviour 5188 * 5189 * The caller must hold a reference on @mm. 5190 * 5191 * Return: number of bytes copied from source to destination. 5192 */ 5193 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 5194 void *buf, int len, unsigned int gup_flags) 5195 { 5196 return __access_remote_vm(mm, addr, buf, len, gup_flags); 5197 } 5198 5199 /* 5200 * Access another process' address space. 5201 * Source/target buffer must be kernel space, 5202 * Do not walk the page table directly, use get_user_pages 5203 */ 5204 int access_process_vm(struct task_struct *tsk, unsigned long addr, 5205 void *buf, int len, unsigned int gup_flags) 5206 { 5207 struct mm_struct *mm; 5208 int ret; 5209 5210 mm = get_task_mm(tsk); 5211 if (!mm) 5212 return 0; 5213 5214 ret = __access_remote_vm(mm, addr, buf, len, gup_flags); 5215 5216 mmput(mm); 5217 5218 return ret; 5219 } 5220 EXPORT_SYMBOL_GPL(access_process_vm); 5221 5222 /* 5223 * Print the name of a VMA. 5224 */ 5225 void print_vma_addr(char *prefix, unsigned long ip) 5226 { 5227 struct mm_struct *mm = current->mm; 5228 struct vm_area_struct *vma; 5229 5230 /* 5231 * we might be running from an atomic context so we cannot sleep 5232 */ 5233 if (!mmap_read_trylock(mm)) 5234 return; 5235 5236 vma = find_vma(mm, ip); 5237 if (vma && vma->vm_file) { 5238 struct file *f = vma->vm_file; 5239 char *buf = (char *)__get_free_page(GFP_NOWAIT); 5240 if (buf) { 5241 char *p; 5242 5243 p = file_path(f, buf, PAGE_SIZE); 5244 if (IS_ERR(p)) 5245 p = "?"; 5246 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 5247 vma->vm_start, 5248 vma->vm_end - vma->vm_start); 5249 free_page((unsigned long)buf); 5250 } 5251 } 5252 mmap_read_unlock(mm); 5253 } 5254 5255 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 5256 void __might_fault(const char *file, int line) 5257 { 5258 if (pagefault_disabled()) 5259 return; 5260 __might_sleep(file, line); 5261 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) 5262 if (current->mm) 5263 might_lock_read(¤t->mm->mmap_lock); 5264 #endif 5265 } 5266 EXPORT_SYMBOL(__might_fault); 5267 #endif 5268 5269 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 5270 /* 5271 * Process all subpages of the specified huge page with the specified 5272 * operation. The target subpage will be processed last to keep its 5273 * cache lines hot. 5274 */ 5275 static inline void process_huge_page( 5276 unsigned long addr_hint, unsigned int pages_per_huge_page, 5277 void (*process_subpage)(unsigned long addr, int idx, void *arg), 5278 void *arg) 5279 { 5280 int i, n, base, l; 5281 unsigned long addr = addr_hint & 5282 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); 5283 5284 /* Process target subpage last to keep its cache lines hot */ 5285 might_sleep(); 5286 n = (addr_hint - addr) / PAGE_SIZE; 5287 if (2 * n <= pages_per_huge_page) { 5288 /* If target subpage in first half of huge page */ 5289 base = 0; 5290 l = n; 5291 /* Process subpages at the end of huge page */ 5292 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { 5293 cond_resched(); 5294 process_subpage(addr + i * PAGE_SIZE, i, arg); 5295 } 5296 } else { 5297 /* If target subpage in second half of huge page */ 5298 base = pages_per_huge_page - 2 * (pages_per_huge_page - n); 5299 l = pages_per_huge_page - n; 5300 /* Process subpages at the begin of huge page */ 5301 for (i = 0; i < base; i++) { 5302 cond_resched(); 5303 process_subpage(addr + i * PAGE_SIZE, i, arg); 5304 } 5305 } 5306 /* 5307 * Process remaining subpages in left-right-left-right pattern 5308 * towards the target subpage 5309 */ 5310 for (i = 0; i < l; i++) { 5311 int left_idx = base + i; 5312 int right_idx = base + 2 * l - 1 - i; 5313 5314 cond_resched(); 5315 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg); 5316 cond_resched(); 5317 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg); 5318 } 5319 } 5320 5321 static void clear_gigantic_page(struct page *page, 5322 unsigned long addr, 5323 unsigned int pages_per_huge_page) 5324 { 5325 int i; 5326 struct page *p = page; 5327 5328 might_sleep(); 5329 for (i = 0; i < pages_per_huge_page; 5330 i++, p = mem_map_next(p, page, i)) { 5331 cond_resched(); 5332 clear_user_highpage(p, addr + i * PAGE_SIZE); 5333 } 5334 } 5335 5336 static void clear_subpage(unsigned long addr, int idx, void *arg) 5337 { 5338 struct page *page = arg; 5339 5340 clear_user_highpage(page + idx, addr); 5341 } 5342 5343 void clear_huge_page(struct page *page, 5344 unsigned long addr_hint, unsigned int pages_per_huge_page) 5345 { 5346 unsigned long addr = addr_hint & 5347 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); 5348 5349 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 5350 clear_gigantic_page(page, addr, pages_per_huge_page); 5351 return; 5352 } 5353 5354 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page); 5355 } 5356 5357 static void copy_user_gigantic_page(struct page *dst, struct page *src, 5358 unsigned long addr, 5359 struct vm_area_struct *vma, 5360 unsigned int pages_per_huge_page) 5361 { 5362 int i; 5363 struct page *dst_base = dst; 5364 struct page *src_base = src; 5365 5366 for (i = 0; i < pages_per_huge_page; ) { 5367 cond_resched(); 5368 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 5369 5370 i++; 5371 dst = mem_map_next(dst, dst_base, i); 5372 src = mem_map_next(src, src_base, i); 5373 } 5374 } 5375 5376 struct copy_subpage_arg { 5377 struct page *dst; 5378 struct page *src; 5379 struct vm_area_struct *vma; 5380 }; 5381 5382 static void copy_subpage(unsigned long addr, int idx, void *arg) 5383 { 5384 struct copy_subpage_arg *copy_arg = arg; 5385 5386 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx, 5387 addr, copy_arg->vma); 5388 } 5389 5390 void copy_user_huge_page(struct page *dst, struct page *src, 5391 unsigned long addr_hint, struct vm_area_struct *vma, 5392 unsigned int pages_per_huge_page) 5393 { 5394 unsigned long addr = addr_hint & 5395 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); 5396 struct copy_subpage_arg arg = { 5397 .dst = dst, 5398 .src = src, 5399 .vma = vma, 5400 }; 5401 5402 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 5403 copy_user_gigantic_page(dst, src, addr, vma, 5404 pages_per_huge_page); 5405 return; 5406 } 5407 5408 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg); 5409 } 5410 5411 long copy_huge_page_from_user(struct page *dst_page, 5412 const void __user *usr_src, 5413 unsigned int pages_per_huge_page, 5414 bool allow_pagefault) 5415 { 5416 void *page_kaddr; 5417 unsigned long i, rc = 0; 5418 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; 5419 struct page *subpage = dst_page; 5420 5421 for (i = 0; i < pages_per_huge_page; 5422 i++, subpage = mem_map_next(subpage, dst_page, i)) { 5423 if (allow_pagefault) 5424 page_kaddr = kmap(subpage); 5425 else 5426 page_kaddr = kmap_atomic(subpage); 5427 rc = copy_from_user(page_kaddr, 5428 usr_src + i * PAGE_SIZE, PAGE_SIZE); 5429 if (allow_pagefault) 5430 kunmap(subpage); 5431 else 5432 kunmap_atomic(page_kaddr); 5433 5434 ret_val -= (PAGE_SIZE - rc); 5435 if (rc) 5436 break; 5437 5438 flush_dcache_page(subpage); 5439 5440 cond_resched(); 5441 } 5442 return ret_val; 5443 } 5444 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 5445 5446 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 5447 5448 static struct kmem_cache *page_ptl_cachep; 5449 5450 void __init ptlock_cache_init(void) 5451 { 5452 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 5453 SLAB_PANIC, NULL); 5454 } 5455 5456 bool ptlock_alloc(struct page *page) 5457 { 5458 spinlock_t *ptl; 5459 5460 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 5461 if (!ptl) 5462 return false; 5463 page->ptl = ptl; 5464 return true; 5465 } 5466 5467 void ptlock_free(struct page *page) 5468 { 5469 kmem_cache_free(page_ptl_cachep, page->ptl); 5470 } 5471 #endif 5472