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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/kmsan.h> | |
56 | #include <linux/ksm.h> | |
57 | #include <linux/rmap.h> | |
58 | #include <linux/export.h> | |
59 | #include <linux/delayacct.h> | |
60 | #include <linux/init.h> | |
61 | #include <linux/pfn_t.h> | |
62 | #include <linux/writeback.h> | |
63 | #include <linux/memcontrol.h> | |
64 | #include <linux/mmu_notifier.h> | |
65 | #include <linux/swapops.h> | |
66 | #include <linux/elf.h> | |
67 | #include <linux/gfp.h> | |
68 | #include <linux/migrate.h> | |
69 | #include <linux/string.h> | |
70 | #include <linux/memory-tiers.h> | |
71 | #include <linux/debugfs.h> | |
72 | #include <linux/userfaultfd_k.h> | |
73 | #include <linux/dax.h> | |
74 | #include <linux/oom.h> | |
75 | #include <linux/numa.h> | |
76 | #include <linux/perf_event.h> | |
77 | #include <linux/ptrace.h> | |
78 | #include <linux/vmalloc.h> | |
79 | #include <linux/sched/sysctl.h> | |
80 | ||
81 | #include <trace/events/kmem.h> | |
82 | ||
83 | #include <asm/io.h> | |
84 | #include <asm/mmu_context.h> | |
85 | #include <asm/pgalloc.h> | |
86 | #include <linux/uaccess.h> | |
87 | #include <asm/tlb.h> | |
88 | #include <asm/tlbflush.h> | |
89 | ||
90 | #include "pgalloc-track.h" | |
91 | #include "internal.h" | |
92 | #include "swap.h" | |
93 | ||
94 | #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST) | |
95 | #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. | |
96 | #endif | |
97 | ||
98 | #ifndef CONFIG_NUMA | |
99 | unsigned long max_mapnr; | |
100 | EXPORT_SYMBOL(max_mapnr); | |
101 | ||
102 | struct page *mem_map; | |
103 | EXPORT_SYMBOL(mem_map); | |
104 | #endif | |
105 | ||
106 | static vm_fault_t do_fault(struct vm_fault *vmf); | |
107 | static vm_fault_t do_anonymous_page(struct vm_fault *vmf); | |
108 | static bool vmf_pte_changed(struct vm_fault *vmf); | |
109 | ||
110 | /* | |
111 | * Return true if the original pte was a uffd-wp pte marker (so the pte was | |
112 | * wr-protected). | |
113 | */ | |
114 | static bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf) | |
115 | { | |
116 | if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) | |
117 | return false; | |
118 | ||
119 | return pte_marker_uffd_wp(vmf->orig_pte); | |
120 | } | |
121 | ||
122 | /* | |
123 | * A number of key systems in x86 including ioremap() rely on the assumption | |
124 | * that high_memory defines the upper bound on direct map memory, then end | |
125 | * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and | |
126 | * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL | |
127 | * and ZONE_HIGHMEM. | |
128 | */ | |
129 | void *high_memory; | |
130 | EXPORT_SYMBOL(high_memory); | |
131 | ||
132 | /* | |
133 | * Randomize the address space (stacks, mmaps, brk, etc.). | |
134 | * | |
135 | * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, | |
136 | * as ancient (libc5 based) binaries can segfault. ) | |
137 | */ | |
138 | int randomize_va_space __read_mostly = | |
139 | #ifdef CONFIG_COMPAT_BRK | |
140 | 1; | |
141 | #else | |
142 | 2; | |
143 | #endif | |
144 | ||
145 | #ifndef arch_wants_old_prefaulted_pte | |
146 | static inline bool arch_wants_old_prefaulted_pte(void) | |
147 | { | |
148 | /* | |
149 | * Transitioning a PTE from 'old' to 'young' can be expensive on | |
150 | * some architectures, even if it's performed in hardware. By | |
151 | * default, "false" means prefaulted entries will be 'young'. | |
152 | */ | |
153 | return false; | |
154 | } | |
155 | #endif | |
156 | ||
157 | static int __init disable_randmaps(char *s) | |
158 | { | |
159 | randomize_va_space = 0; | |
160 | return 1; | |
161 | } | |
162 | __setup("norandmaps", disable_randmaps); | |
163 | ||
164 | unsigned long zero_pfn __read_mostly; | |
165 | EXPORT_SYMBOL(zero_pfn); | |
166 | ||
167 | unsigned long highest_memmap_pfn __read_mostly; | |
168 | ||
169 | /* | |
170 | * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() | |
171 | */ | |
172 | static int __init init_zero_pfn(void) | |
173 | { | |
174 | zero_pfn = page_to_pfn(ZERO_PAGE(0)); | |
175 | return 0; | |
176 | } | |
177 | early_initcall(init_zero_pfn); | |
178 | ||
179 | void mm_trace_rss_stat(struct mm_struct *mm, int member) | |
180 | { | |
181 | trace_rss_stat(mm, member); | |
182 | } | |
183 | ||
184 | /* | |
185 | * Note: this doesn't free the actual pages themselves. That | |
186 | * has been handled earlier when unmapping all the memory regions. | |
187 | */ | |
188 | static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, | |
189 | unsigned long addr) | |
190 | { | |
191 | pgtable_t token = pmd_pgtable(*pmd); | |
192 | pmd_clear(pmd); | |
193 | pte_free_tlb(tlb, token, addr); | |
194 | mm_dec_nr_ptes(tlb->mm); | |
195 | } | |
196 | ||
197 | static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, | |
198 | unsigned long addr, unsigned long end, | |
199 | unsigned long floor, unsigned long ceiling) | |
200 | { | |
201 | pmd_t *pmd; | |
202 | unsigned long next; | |
203 | unsigned long start; | |
204 | ||
205 | start = addr; | |
206 | pmd = pmd_offset(pud, addr); | |
207 | do { | |
208 | next = pmd_addr_end(addr, end); | |
209 | if (pmd_none_or_clear_bad(pmd)) | |
210 | continue; | |
211 | free_pte_range(tlb, pmd, addr); | |
212 | } while (pmd++, addr = next, addr != end); | |
213 | ||
214 | start &= PUD_MASK; | |
215 | if (start < floor) | |
216 | return; | |
217 | if (ceiling) { | |
218 | ceiling &= PUD_MASK; | |
219 | if (!ceiling) | |
220 | return; | |
221 | } | |
222 | if (end - 1 > ceiling - 1) | |
223 | return; | |
224 | ||
225 | pmd = pmd_offset(pud, start); | |
226 | pud_clear(pud); | |
227 | pmd_free_tlb(tlb, pmd, start); | |
228 | mm_dec_nr_pmds(tlb->mm); | |
229 | } | |
230 | ||
231 | static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, | |
232 | unsigned long addr, unsigned long end, | |
233 | unsigned long floor, unsigned long ceiling) | |
234 | { | |
235 | pud_t *pud; | |
236 | unsigned long next; | |
237 | unsigned long start; | |
238 | ||
239 | start = addr; | |
240 | pud = pud_offset(p4d, addr); | |
241 | do { | |
242 | next = pud_addr_end(addr, end); | |
243 | if (pud_none_or_clear_bad(pud)) | |
244 | continue; | |
245 | free_pmd_range(tlb, pud, addr, next, floor, ceiling); | |
246 | } while (pud++, addr = next, addr != end); | |
247 | ||
248 | start &= P4D_MASK; | |
249 | if (start < floor) | |
250 | return; | |
251 | if (ceiling) { | |
252 | ceiling &= P4D_MASK; | |
253 | if (!ceiling) | |
254 | return; | |
255 | } | |
256 | if (end - 1 > ceiling - 1) | |
257 | return; | |
258 | ||
259 | pud = pud_offset(p4d, start); | |
260 | p4d_clear(p4d); | |
261 | pud_free_tlb(tlb, pud, start); | |
262 | mm_dec_nr_puds(tlb->mm); | |
263 | } | |
264 | ||
265 | static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, | |
266 | unsigned long addr, unsigned long end, | |
267 | unsigned long floor, unsigned long ceiling) | |
268 | { | |
269 | p4d_t *p4d; | |
270 | unsigned long next; | |
271 | unsigned long start; | |
272 | ||
273 | start = addr; | |
274 | p4d = p4d_offset(pgd, addr); | |
275 | do { | |
276 | next = p4d_addr_end(addr, end); | |
277 | if (p4d_none_or_clear_bad(p4d)) | |
278 | continue; | |
279 | free_pud_range(tlb, p4d, addr, next, floor, ceiling); | |
280 | } while (p4d++, addr = next, addr != end); | |
281 | ||
282 | start &= PGDIR_MASK; | |
283 | if (start < floor) | |
284 | return; | |
285 | if (ceiling) { | |
286 | ceiling &= PGDIR_MASK; | |
287 | if (!ceiling) | |
288 | return; | |
289 | } | |
290 | if (end - 1 > ceiling - 1) | |
291 | return; | |
292 | ||
293 | p4d = p4d_offset(pgd, start); | |
294 | pgd_clear(pgd); | |
295 | p4d_free_tlb(tlb, p4d, start); | |
296 | } | |
297 | ||
298 | /* | |
299 | * This function frees user-level page tables of a process. | |
300 | */ | |
301 | void free_pgd_range(struct mmu_gather *tlb, | |
302 | unsigned long addr, unsigned long end, | |
303 | unsigned long floor, unsigned long ceiling) | |
304 | { | |
305 | pgd_t *pgd; | |
306 | unsigned long next; | |
307 | ||
308 | /* | |
309 | * The next few lines have given us lots of grief... | |
310 | * | |
311 | * Why are we testing PMD* at this top level? Because often | |
312 | * there will be no work to do at all, and we'd prefer not to | |
313 | * go all the way down to the bottom just to discover that. | |
314 | * | |
315 | * Why all these "- 1"s? Because 0 represents both the bottom | |
316 | * of the address space and the top of it (using -1 for the | |
317 | * top wouldn't help much: the masks would do the wrong thing). | |
318 | * The rule is that addr 0 and floor 0 refer to the bottom of | |
319 | * the address space, but end 0 and ceiling 0 refer to the top | |
320 | * Comparisons need to use "end - 1" and "ceiling - 1" (though | |
321 | * that end 0 case should be mythical). | |
322 | * | |
323 | * Wherever addr is brought up or ceiling brought down, we must | |
324 | * be careful to reject "the opposite 0" before it confuses the | |
325 | * subsequent tests. But what about where end is brought down | |
326 | * by PMD_SIZE below? no, end can't go down to 0 there. | |
327 | * | |
328 | * Whereas we round start (addr) and ceiling down, by different | |
329 | * masks at different levels, in order to test whether a table | |
330 | * now has no other vmas using it, so can be freed, we don't | |
331 | * bother to round floor or end up - the tests don't need that. | |
332 | */ | |
333 | ||
334 | addr &= PMD_MASK; | |
335 | if (addr < floor) { | |
336 | addr += PMD_SIZE; | |
337 | if (!addr) | |
338 | return; | |
339 | } | |
340 | if (ceiling) { | |
341 | ceiling &= PMD_MASK; | |
342 | if (!ceiling) | |
343 | return; | |
344 | } | |
345 | if (end - 1 > ceiling - 1) | |
346 | end -= PMD_SIZE; | |
347 | if (addr > end - 1) | |
348 | return; | |
349 | /* | |
350 | * We add page table cache pages with PAGE_SIZE, | |
351 | * (see pte_free_tlb()), flush the tlb if we need | |
352 | */ | |
353 | tlb_change_page_size(tlb, PAGE_SIZE); | |
354 | pgd = pgd_offset(tlb->mm, addr); | |
355 | do { | |
356 | next = pgd_addr_end(addr, end); | |
357 | if (pgd_none_or_clear_bad(pgd)) | |
358 | continue; | |
359 | free_p4d_range(tlb, pgd, addr, next, floor, ceiling); | |
360 | } while (pgd++, addr = next, addr != end); | |
361 | } | |
362 | ||
363 | void free_pgtables(struct mmu_gather *tlb, struct ma_state *mas, | |
364 | struct vm_area_struct *vma, unsigned long floor, | |
365 | unsigned long ceiling, bool mm_wr_locked) | |
366 | { | |
367 | do { | |
368 | unsigned long addr = vma->vm_start; | |
369 | struct vm_area_struct *next; | |
370 | ||
371 | /* | |
372 | * Note: USER_PGTABLES_CEILING may be passed as ceiling and may | |
373 | * be 0. This will underflow and is okay. | |
374 | */ | |
375 | next = mas_find(mas, ceiling - 1); | |
376 | ||
377 | /* | |
378 | * Hide vma from rmap and truncate_pagecache before freeing | |
379 | * pgtables | |
380 | */ | |
381 | if (mm_wr_locked) | |
382 | vma_start_write(vma); | |
383 | unlink_anon_vmas(vma); | |
384 | unlink_file_vma(vma); | |
385 | ||
386 | if (is_vm_hugetlb_page(vma)) { | |
387 | hugetlb_free_pgd_range(tlb, addr, vma->vm_end, | |
388 | floor, next ? next->vm_start : ceiling); | |
389 | } else { | |
390 | /* | |
391 | * Optimization: gather nearby vmas into one call down | |
392 | */ | |
393 | while (next && next->vm_start <= vma->vm_end + PMD_SIZE | |
394 | && !is_vm_hugetlb_page(next)) { | |
395 | vma = next; | |
396 | next = mas_find(mas, ceiling - 1); | |
397 | if (mm_wr_locked) | |
398 | vma_start_write(vma); | |
399 | unlink_anon_vmas(vma); | |
400 | unlink_file_vma(vma); | |
401 | } | |
402 | free_pgd_range(tlb, addr, vma->vm_end, | |
403 | floor, next ? next->vm_start : ceiling); | |
404 | } | |
405 | vma = next; | |
406 | } while (vma); | |
407 | } | |
408 | ||
409 | void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte) | |
410 | { | |
411 | spinlock_t *ptl = pmd_lock(mm, pmd); | |
412 | ||
413 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ | |
414 | mm_inc_nr_ptes(mm); | |
415 | /* | |
416 | * Ensure all pte setup (eg. pte page lock and page clearing) are | |
417 | * visible before the pte is made visible to other CPUs by being | |
418 | * put into page tables. | |
419 | * | |
420 | * The other side of the story is the pointer chasing in the page | |
421 | * table walking code (when walking the page table without locking; | |
422 | * ie. most of the time). Fortunately, these data accesses consist | |
423 | * of a chain of data-dependent loads, meaning most CPUs (alpha | |
424 | * being the notable exception) will already guarantee loads are | |
425 | * seen in-order. See the alpha page table accessors for the | |
426 | * smp_rmb() barriers in page table walking code. | |
427 | */ | |
428 | smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ | |
429 | pmd_populate(mm, pmd, *pte); | |
430 | *pte = NULL; | |
431 | } | |
432 | spin_unlock(ptl); | |
433 | } | |
434 | ||
435 | int __pte_alloc(struct mm_struct *mm, pmd_t *pmd) | |
436 | { | |
437 | pgtable_t new = pte_alloc_one(mm); | |
438 | if (!new) | |
439 | return -ENOMEM; | |
440 | ||
441 | pmd_install(mm, pmd, &new); | |
442 | if (new) | |
443 | pte_free(mm, new); | |
444 | return 0; | |
445 | } | |
446 | ||
447 | int __pte_alloc_kernel(pmd_t *pmd) | |
448 | { | |
449 | pte_t *new = pte_alloc_one_kernel(&init_mm); | |
450 | if (!new) | |
451 | return -ENOMEM; | |
452 | ||
453 | spin_lock(&init_mm.page_table_lock); | |
454 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ | |
455 | smp_wmb(); /* See comment in pmd_install() */ | |
456 | pmd_populate_kernel(&init_mm, pmd, new); | |
457 | new = NULL; | |
458 | } | |
459 | spin_unlock(&init_mm.page_table_lock); | |
460 | if (new) | |
461 | pte_free_kernel(&init_mm, new); | |
462 | return 0; | |
463 | } | |
464 | ||
465 | static inline void init_rss_vec(int *rss) | |
466 | { | |
467 | memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); | |
468 | } | |
469 | ||
470 | static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) | |
471 | { | |
472 | int i; | |
473 | ||
474 | if (current->mm == mm) | |
475 | sync_mm_rss(mm); | |
476 | for (i = 0; i < NR_MM_COUNTERS; i++) | |
477 | if (rss[i]) | |
478 | add_mm_counter(mm, i, rss[i]); | |
479 | } | |
480 | ||
481 | /* | |
482 | * This function is called to print an error when a bad pte | |
483 | * is found. For example, we might have a PFN-mapped pte in | |
484 | * a region that doesn't allow it. | |
485 | * | |
486 | * The calling function must still handle the error. | |
487 | */ | |
488 | static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, | |
489 | pte_t pte, struct page *page) | |
490 | { | |
491 | pgd_t *pgd = pgd_offset(vma->vm_mm, addr); | |
492 | p4d_t *p4d = p4d_offset(pgd, addr); | |
493 | pud_t *pud = pud_offset(p4d, addr); | |
494 | pmd_t *pmd = pmd_offset(pud, addr); | |
495 | struct address_space *mapping; | |
496 | pgoff_t index; | |
497 | static unsigned long resume; | |
498 | static unsigned long nr_shown; | |
499 | static unsigned long nr_unshown; | |
500 | ||
501 | /* | |
502 | * Allow a burst of 60 reports, then keep quiet for that minute; | |
503 | * or allow a steady drip of one report per second. | |
504 | */ | |
505 | if (nr_shown == 60) { | |
506 | if (time_before(jiffies, resume)) { | |
507 | nr_unshown++; | |
508 | return; | |
509 | } | |
510 | if (nr_unshown) { | |
511 | pr_alert("BUG: Bad page map: %lu messages suppressed\n", | |
512 | nr_unshown); | |
513 | nr_unshown = 0; | |
514 | } | |
515 | nr_shown = 0; | |
516 | } | |
517 | if (nr_shown++ == 0) | |
518 | resume = jiffies + 60 * HZ; | |
519 | ||
520 | mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; | |
521 | index = linear_page_index(vma, addr); | |
522 | ||
523 | pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", | |
524 | current->comm, | |
525 | (long long)pte_val(pte), (long long)pmd_val(*pmd)); | |
526 | if (page) | |
527 | dump_page(page, "bad pte"); | |
528 | pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n", | |
529 | (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); | |
530 | pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n", | |
531 | vma->vm_file, | |
532 | vma->vm_ops ? vma->vm_ops->fault : NULL, | |
533 | vma->vm_file ? vma->vm_file->f_op->mmap : NULL, | |
534 | mapping ? mapping->a_ops->read_folio : NULL); | |
535 | dump_stack(); | |
536 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); | |
537 | } | |
538 | ||
539 | /* | |
540 | * vm_normal_page -- This function gets the "struct page" associated with a pte. | |
541 | * | |
542 | * "Special" mappings do not wish to be associated with a "struct page" (either | |
543 | * it doesn't exist, or it exists but they don't want to touch it). In this | |
544 | * case, NULL is returned here. "Normal" mappings do have a struct page. | |
545 | * | |
546 | * There are 2 broad cases. Firstly, an architecture may define a pte_special() | |
547 | * pte bit, in which case this function is trivial. Secondly, an architecture | |
548 | * may not have a spare pte bit, which requires a more complicated scheme, | |
549 | * described below. | |
550 | * | |
551 | * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a | |
552 | * special mapping (even if there are underlying and valid "struct pages"). | |
553 | * COWed pages of a VM_PFNMAP are always normal. | |
554 | * | |
555 | * The way we recognize COWed pages within VM_PFNMAP mappings is through the | |
556 | * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit | |
557 | * set, and the vm_pgoff will point to the first PFN mapped: thus every special | |
558 | * mapping will always honor the rule | |
559 | * | |
560 | * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) | |
561 | * | |
562 | * And for normal mappings this is false. | |
563 | * | |
564 | * This restricts such mappings to be a linear translation from virtual address | |
565 | * to pfn. To get around this restriction, we allow arbitrary mappings so long | |
566 | * as the vma is not a COW mapping; in that case, we know that all ptes are | |
567 | * special (because none can have been COWed). | |
568 | * | |
569 | * | |
570 | * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. | |
571 | * | |
572 | * VM_MIXEDMAP mappings can likewise contain memory with or without "struct | |
573 | * page" backing, however the difference is that _all_ pages with a struct | |
574 | * page (that is, those where pfn_valid is true) are refcounted and considered | |
575 | * normal pages by the VM. The disadvantage is that pages are refcounted | |
576 | * (which can be slower and simply not an option for some PFNMAP users). The | |
577 | * advantage is that we don't have to follow the strict linearity rule of | |
578 | * PFNMAP mappings in order to support COWable mappings. | |
579 | * | |
580 | */ | |
581 | struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, | |
582 | pte_t pte) | |
583 | { | |
584 | unsigned long pfn = pte_pfn(pte); | |
585 | ||
586 | if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { | |
587 | if (likely(!pte_special(pte))) | |
588 | goto check_pfn; | |
589 | if (vma->vm_ops && vma->vm_ops->find_special_page) | |
590 | return vma->vm_ops->find_special_page(vma, addr); | |
591 | if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) | |
592 | return NULL; | |
593 | if (is_zero_pfn(pfn)) | |
594 | return NULL; | |
595 | if (pte_devmap(pte)) | |
596 | /* | |
597 | * NOTE: New users of ZONE_DEVICE will not set pte_devmap() | |
598 | * and will have refcounts incremented on their struct pages | |
599 | * when they are inserted into PTEs, thus they are safe to | |
600 | * return here. Legacy ZONE_DEVICE pages that set pte_devmap() | |
601 | * do not have refcounts. Example of legacy ZONE_DEVICE is | |
602 | * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. | |
603 | */ | |
604 | return NULL; | |
605 | ||
606 | print_bad_pte(vma, addr, pte, NULL); | |
607 | return NULL; | |
608 | } | |
609 | ||
610 | /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ | |
611 | ||
612 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { | |
613 | if (vma->vm_flags & VM_MIXEDMAP) { | |
614 | if (!pfn_valid(pfn)) | |
615 | return NULL; | |
616 | goto out; | |
617 | } else { | |
618 | unsigned long off; | |
619 | off = (addr - vma->vm_start) >> PAGE_SHIFT; | |
620 | if (pfn == vma->vm_pgoff + off) | |
621 | return NULL; | |
622 | if (!is_cow_mapping(vma->vm_flags)) | |
623 | return NULL; | |
624 | } | |
625 | } | |
626 | ||
627 | if (is_zero_pfn(pfn)) | |
628 | return NULL; | |
629 | ||
630 | check_pfn: | |
631 | if (unlikely(pfn > highest_memmap_pfn)) { | |
632 | print_bad_pte(vma, addr, pte, NULL); | |
633 | return NULL; | |
634 | } | |
635 | ||
636 | /* | |
637 | * NOTE! We still have PageReserved() pages in the page tables. | |
638 | * eg. VDSO mappings can cause them to exist. | |
639 | */ | |
640 | out: | |
641 | return pfn_to_page(pfn); | |
642 | } | |
643 | ||
644 | struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr, | |
645 | pte_t pte) | |
646 | { | |
647 | struct page *page = vm_normal_page(vma, addr, pte); | |
648 | ||
649 | if (page) | |
650 | return page_folio(page); | |
651 | return NULL; | |
652 | } | |
653 | ||
654 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
655 | struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, | |
656 | pmd_t pmd) | |
657 | { | |
658 | unsigned long pfn = pmd_pfn(pmd); | |
659 | ||
660 | /* | |
661 | * There is no pmd_special() but there may be special pmds, e.g. | |
662 | * in a direct-access (dax) mapping, so let's just replicate the | |
663 | * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. | |
664 | */ | |
665 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { | |
666 | if (vma->vm_flags & VM_MIXEDMAP) { | |
667 | if (!pfn_valid(pfn)) | |
668 | return NULL; | |
669 | goto out; | |
670 | } else { | |
671 | unsigned long off; | |
672 | off = (addr - vma->vm_start) >> PAGE_SHIFT; | |
673 | if (pfn == vma->vm_pgoff + off) | |
674 | return NULL; | |
675 | if (!is_cow_mapping(vma->vm_flags)) | |
676 | return NULL; | |
677 | } | |
678 | } | |
679 | ||
680 | if (pmd_devmap(pmd)) | |
681 | return NULL; | |
682 | if (is_huge_zero_pmd(pmd)) | |
683 | return NULL; | |
684 | if (unlikely(pfn > highest_memmap_pfn)) | |
685 | return NULL; | |
686 | ||
687 | /* | |
688 | * NOTE! We still have PageReserved() pages in the page tables. | |
689 | * eg. VDSO mappings can cause them to exist. | |
690 | */ | |
691 | out: | |
692 | return pfn_to_page(pfn); | |
693 | } | |
694 | #endif | |
695 | ||
696 | static void restore_exclusive_pte(struct vm_area_struct *vma, | |
697 | struct page *page, unsigned long address, | |
698 | pte_t *ptep) | |
699 | { | |
700 | pte_t orig_pte; | |
701 | pte_t pte; | |
702 | swp_entry_t entry; | |
703 | ||
704 | orig_pte = ptep_get(ptep); | |
705 | pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); | |
706 | if (pte_swp_soft_dirty(orig_pte)) | |
707 | pte = pte_mksoft_dirty(pte); | |
708 | ||
709 | entry = pte_to_swp_entry(orig_pte); | |
710 | if (pte_swp_uffd_wp(orig_pte)) | |
711 | pte = pte_mkuffd_wp(pte); | |
712 | else if (is_writable_device_exclusive_entry(entry)) | |
713 | pte = maybe_mkwrite(pte_mkdirty(pte), vma); | |
714 | ||
715 | VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page))); | |
716 | ||
717 | /* | |
718 | * No need to take a page reference as one was already | |
719 | * created when the swap entry was made. | |
720 | */ | |
721 | if (PageAnon(page)) | |
722 | page_add_anon_rmap(page, vma, address, RMAP_NONE); | |
723 | else | |
724 | /* | |
725 | * Currently device exclusive access only supports anonymous | |
726 | * memory so the entry shouldn't point to a filebacked page. | |
727 | */ | |
728 | WARN_ON_ONCE(1); | |
729 | ||
730 | set_pte_at(vma->vm_mm, address, ptep, pte); | |
731 | ||
732 | /* | |
733 | * No need to invalidate - it was non-present before. However | |
734 | * secondary CPUs may have mappings that need invalidating. | |
735 | */ | |
736 | update_mmu_cache(vma, address, ptep); | |
737 | } | |
738 | ||
739 | /* | |
740 | * Tries to restore an exclusive pte if the page lock can be acquired without | |
741 | * sleeping. | |
742 | */ | |
743 | static int | |
744 | try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, | |
745 | unsigned long addr) | |
746 | { | |
747 | swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte)); | |
748 | struct page *page = pfn_swap_entry_to_page(entry); | |
749 | ||
750 | if (trylock_page(page)) { | |
751 | restore_exclusive_pte(vma, page, addr, src_pte); | |
752 | unlock_page(page); | |
753 | return 0; | |
754 | } | |
755 | ||
756 | return -EBUSY; | |
757 | } | |
758 | ||
759 | /* | |
760 | * copy one vm_area from one task to the other. Assumes the page tables | |
761 | * already present in the new task to be cleared in the whole range | |
762 | * covered by this vma. | |
763 | */ | |
764 | ||
765 | static unsigned long | |
766 | copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
767 | pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, | |
768 | struct vm_area_struct *src_vma, unsigned long addr, int *rss) | |
769 | { | |
770 | unsigned long vm_flags = dst_vma->vm_flags; | |
771 | pte_t orig_pte = ptep_get(src_pte); | |
772 | pte_t pte = orig_pte; | |
773 | struct page *page; | |
774 | swp_entry_t entry = pte_to_swp_entry(orig_pte); | |
775 | ||
776 | if (likely(!non_swap_entry(entry))) { | |
777 | if (swap_duplicate(entry) < 0) | |
778 | return -EIO; | |
779 | ||
780 | /* make sure dst_mm is on swapoff's mmlist. */ | |
781 | if (unlikely(list_empty(&dst_mm->mmlist))) { | |
782 | spin_lock(&mmlist_lock); | |
783 | if (list_empty(&dst_mm->mmlist)) | |
784 | list_add(&dst_mm->mmlist, | |
785 | &src_mm->mmlist); | |
786 | spin_unlock(&mmlist_lock); | |
787 | } | |
788 | /* Mark the swap entry as shared. */ | |
789 | if (pte_swp_exclusive(orig_pte)) { | |
790 | pte = pte_swp_clear_exclusive(orig_pte); | |
791 | set_pte_at(src_mm, addr, src_pte, pte); | |
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_readable_migration_entry(entry) && | |
800 | is_cow_mapping(vm_flags)) { | |
801 | /* | |
802 | * COW mappings require pages in both parent and child | |
803 | * to be set to read. A previously exclusive entry is | |
804 | * now shared. | |
805 | */ | |
806 | entry = make_readable_migration_entry( | |
807 | swp_offset(entry)); | |
808 | pte = swp_entry_to_pte(entry); | |
809 | if (pte_swp_soft_dirty(orig_pte)) | |
810 | pte = pte_swp_mksoft_dirty(pte); | |
811 | if (pte_swp_uffd_wp(orig_pte)) | |
812 | pte = pte_swp_mkuffd_wp(pte); | |
813 | set_pte_at(src_mm, addr, src_pte, pte); | |
814 | } | |
815 | } else if (is_device_private_entry(entry)) { | |
816 | page = pfn_swap_entry_to_page(entry); | |
817 | ||
818 | /* | |
819 | * Update rss count even for unaddressable pages, as | |
820 | * they should treated just like normal pages in this | |
821 | * respect. | |
822 | * | |
823 | * We will likely want to have some new rss counters | |
824 | * for unaddressable pages, at some point. But for now | |
825 | * keep things as they are. | |
826 | */ | |
827 | get_page(page); | |
828 | rss[mm_counter(page)]++; | |
829 | /* Cannot fail as these pages cannot get pinned. */ | |
830 | BUG_ON(page_try_dup_anon_rmap(page, false, src_vma)); | |
831 | ||
832 | /* | |
833 | * We do not preserve soft-dirty information, because so | |
834 | * far, checkpoint/restore is the only feature that | |
835 | * requires that. And checkpoint/restore does not work | |
836 | * when a device driver is involved (you cannot easily | |
837 | * save and restore device driver state). | |
838 | */ | |
839 | if (is_writable_device_private_entry(entry) && | |
840 | is_cow_mapping(vm_flags)) { | |
841 | entry = make_readable_device_private_entry( | |
842 | swp_offset(entry)); | |
843 | pte = swp_entry_to_pte(entry); | |
844 | if (pte_swp_uffd_wp(orig_pte)) | |
845 | pte = pte_swp_mkuffd_wp(pte); | |
846 | set_pte_at(src_mm, addr, src_pte, pte); | |
847 | } | |
848 | } else if (is_device_exclusive_entry(entry)) { | |
849 | /* | |
850 | * Make device exclusive entries present by restoring the | |
851 | * original entry then copying as for a present pte. Device | |
852 | * exclusive entries currently only support private writable | |
853 | * (ie. COW) mappings. | |
854 | */ | |
855 | VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); | |
856 | if (try_restore_exclusive_pte(src_pte, src_vma, addr)) | |
857 | return -EBUSY; | |
858 | return -ENOENT; | |
859 | } else if (is_pte_marker_entry(entry)) { | |
860 | pte_marker marker = copy_pte_marker(entry, dst_vma); | |
861 | ||
862 | if (marker) | |
863 | set_pte_at(dst_mm, addr, dst_pte, | |
864 | make_pte_marker(marker)); | |
865 | return 0; | |
866 | } | |
867 | if (!userfaultfd_wp(dst_vma)) | |
868 | pte = pte_swp_clear_uffd_wp(pte); | |
869 | set_pte_at(dst_mm, addr, dst_pte, pte); | |
870 | return 0; | |
871 | } | |
872 | ||
873 | /* | |
874 | * Copy a present and normal page. | |
875 | * | |
876 | * NOTE! The usual case is that this isn't required; | |
877 | * instead, the caller can just increase the page refcount | |
878 | * and re-use the pte the traditional way. | |
879 | * | |
880 | * And if we need a pre-allocated page but don't yet have | |
881 | * one, return a negative error to let the preallocation | |
882 | * code know so that it can do so outside the page table | |
883 | * lock. | |
884 | */ | |
885 | static inline int | |
886 | copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
887 | pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, | |
888 | struct folio **prealloc, struct page *page) | |
889 | { | |
890 | struct folio *new_folio; | |
891 | pte_t pte; | |
892 | ||
893 | new_folio = *prealloc; | |
894 | if (!new_folio) | |
895 | return -EAGAIN; | |
896 | ||
897 | /* | |
898 | * We have a prealloc page, all good! Take it | |
899 | * over and copy the page & arm it. | |
900 | */ | |
901 | *prealloc = NULL; | |
902 | copy_user_highpage(&new_folio->page, page, addr, src_vma); | |
903 | __folio_mark_uptodate(new_folio); | |
904 | folio_add_new_anon_rmap(new_folio, dst_vma, addr); | |
905 | folio_add_lru_vma(new_folio, dst_vma); | |
906 | rss[MM_ANONPAGES]++; | |
907 | ||
908 | /* All done, just insert the new page copy in the child */ | |
909 | pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot); | |
910 | pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma); | |
911 | if (userfaultfd_pte_wp(dst_vma, ptep_get(src_pte))) | |
912 | /* Uffd-wp needs to be delivered to dest pte as well */ | |
913 | pte = pte_mkuffd_wp(pte); | |
914 | set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); | |
915 | return 0; | |
916 | } | |
917 | ||
918 | /* | |
919 | * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page | |
920 | * is required to copy this pte. | |
921 | */ | |
922 | static inline int | |
923 | copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
924 | pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, | |
925 | struct folio **prealloc) | |
926 | { | |
927 | struct mm_struct *src_mm = src_vma->vm_mm; | |
928 | unsigned long vm_flags = src_vma->vm_flags; | |
929 | pte_t pte = ptep_get(src_pte); | |
930 | struct page *page; | |
931 | struct folio *folio; | |
932 | ||
933 | page = vm_normal_page(src_vma, addr, pte); | |
934 | if (page) | |
935 | folio = page_folio(page); | |
936 | if (page && folio_test_anon(folio)) { | |
937 | /* | |
938 | * If this page may have been pinned by the parent process, | |
939 | * copy the page immediately for the child so that we'll always | |
940 | * guarantee the pinned page won't be randomly replaced in the | |
941 | * future. | |
942 | */ | |
943 | folio_get(folio); | |
944 | if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) { | |
945 | /* Page may be pinned, we have to copy. */ | |
946 | folio_put(folio); | |
947 | return copy_present_page(dst_vma, src_vma, dst_pte, src_pte, | |
948 | addr, rss, prealloc, page); | |
949 | } | |
950 | rss[MM_ANONPAGES]++; | |
951 | } else if (page) { | |
952 | folio_get(folio); | |
953 | page_dup_file_rmap(page, false); | |
954 | rss[mm_counter_file(page)]++; | |
955 | } | |
956 | ||
957 | /* | |
958 | * If it's a COW mapping, write protect it both | |
959 | * in the parent and the child | |
960 | */ | |
961 | if (is_cow_mapping(vm_flags) && pte_write(pte)) { | |
962 | ptep_set_wrprotect(src_mm, addr, src_pte); | |
963 | pte = pte_wrprotect(pte); | |
964 | } | |
965 | VM_BUG_ON(page && folio_test_anon(folio) && PageAnonExclusive(page)); | |
966 | ||
967 | /* | |
968 | * If it's a shared mapping, mark it clean in | |
969 | * the child | |
970 | */ | |
971 | if (vm_flags & VM_SHARED) | |
972 | pte = pte_mkclean(pte); | |
973 | pte = pte_mkold(pte); | |
974 | ||
975 | if (!userfaultfd_wp(dst_vma)) | |
976 | pte = pte_clear_uffd_wp(pte); | |
977 | ||
978 | set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); | |
979 | return 0; | |
980 | } | |
981 | ||
982 | static inline struct folio *page_copy_prealloc(struct mm_struct *src_mm, | |
983 | struct vm_area_struct *vma, unsigned long addr) | |
984 | { | |
985 | struct folio *new_folio; | |
986 | ||
987 | new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, addr, false); | |
988 | if (!new_folio) | |
989 | return NULL; | |
990 | ||
991 | if (mem_cgroup_charge(new_folio, src_mm, GFP_KERNEL)) { | |
992 | folio_put(new_folio); | |
993 | return NULL; | |
994 | } | |
995 | folio_throttle_swaprate(new_folio, GFP_KERNEL); | |
996 | ||
997 | return new_folio; | |
998 | } | |
999 | ||
1000 | static int | |
1001 | copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
1002 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
1003 | unsigned long end) | |
1004 | { | |
1005 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
1006 | struct mm_struct *src_mm = src_vma->vm_mm; | |
1007 | pte_t *orig_src_pte, *orig_dst_pte; | |
1008 | pte_t *src_pte, *dst_pte; | |
1009 | pte_t ptent; | |
1010 | spinlock_t *src_ptl, *dst_ptl; | |
1011 | int progress, ret = 0; | |
1012 | int rss[NR_MM_COUNTERS]; | |
1013 | swp_entry_t entry = (swp_entry_t){0}; | |
1014 | struct folio *prealloc = NULL; | |
1015 | ||
1016 | again: | |
1017 | progress = 0; | |
1018 | init_rss_vec(rss); | |
1019 | ||
1020 | /* | |
1021 | * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the | |
1022 | * error handling here, assume that exclusive mmap_lock on dst and src | |
1023 | * protects anon from unexpected THP transitions; with shmem and file | |
1024 | * protected by mmap_lock-less collapse skipping areas with anon_vma | |
1025 | * (whereas vma_needs_copy() skips areas without anon_vma). A rework | |
1026 | * can remove such assumptions later, but this is good enough for now. | |
1027 | */ | |
1028 | dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); | |
1029 | if (!dst_pte) { | |
1030 | ret = -ENOMEM; | |
1031 | goto out; | |
1032 | } | |
1033 | src_pte = pte_offset_map_nolock(src_mm, src_pmd, addr, &src_ptl); | |
1034 | if (!src_pte) { | |
1035 | pte_unmap_unlock(dst_pte, dst_ptl); | |
1036 | /* ret == 0 */ | |
1037 | goto out; | |
1038 | } | |
1039 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
1040 | orig_src_pte = src_pte; | |
1041 | orig_dst_pte = dst_pte; | |
1042 | arch_enter_lazy_mmu_mode(); | |
1043 | ||
1044 | do { | |
1045 | /* | |
1046 | * We are holding two locks at this point - either of them | |
1047 | * could generate latencies in another task on another CPU. | |
1048 | */ | |
1049 | if (progress >= 32) { | |
1050 | progress = 0; | |
1051 | if (need_resched() || | |
1052 | spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) | |
1053 | break; | |
1054 | } | |
1055 | ptent = ptep_get(src_pte); | |
1056 | if (pte_none(ptent)) { | |
1057 | progress++; | |
1058 | continue; | |
1059 | } | |
1060 | if (unlikely(!pte_present(ptent))) { | |
1061 | ret = copy_nonpresent_pte(dst_mm, src_mm, | |
1062 | dst_pte, src_pte, | |
1063 | dst_vma, src_vma, | |
1064 | addr, rss); | |
1065 | if (ret == -EIO) { | |
1066 | entry = pte_to_swp_entry(ptep_get(src_pte)); | |
1067 | break; | |
1068 | } else if (ret == -EBUSY) { | |
1069 | break; | |
1070 | } else if (!ret) { | |
1071 | progress += 8; | |
1072 | continue; | |
1073 | } | |
1074 | ||
1075 | /* | |
1076 | * Device exclusive entry restored, continue by copying | |
1077 | * the now present pte. | |
1078 | */ | |
1079 | WARN_ON_ONCE(ret != -ENOENT); | |
1080 | } | |
1081 | /* copy_present_pte() will clear `*prealloc' if consumed */ | |
1082 | ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte, | |
1083 | addr, rss, &prealloc); | |
1084 | /* | |
1085 | * If we need a pre-allocated page for this pte, drop the | |
1086 | * locks, allocate, and try again. | |
1087 | */ | |
1088 | if (unlikely(ret == -EAGAIN)) | |
1089 | break; | |
1090 | if (unlikely(prealloc)) { | |
1091 | /* | |
1092 | * pre-alloc page cannot be reused by next time so as | |
1093 | * to strictly follow mempolicy (e.g., alloc_page_vma() | |
1094 | * will allocate page according to address). This | |
1095 | * could only happen if one pinned pte changed. | |
1096 | */ | |
1097 | folio_put(prealloc); | |
1098 | prealloc = NULL; | |
1099 | } | |
1100 | progress += 8; | |
1101 | } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); | |
1102 | ||
1103 | arch_leave_lazy_mmu_mode(); | |
1104 | pte_unmap_unlock(orig_src_pte, src_ptl); | |
1105 | add_mm_rss_vec(dst_mm, rss); | |
1106 | pte_unmap_unlock(orig_dst_pte, dst_ptl); | |
1107 | cond_resched(); | |
1108 | ||
1109 | if (ret == -EIO) { | |
1110 | VM_WARN_ON_ONCE(!entry.val); | |
1111 | if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { | |
1112 | ret = -ENOMEM; | |
1113 | goto out; | |
1114 | } | |
1115 | entry.val = 0; | |
1116 | } else if (ret == -EBUSY) { | |
1117 | goto out; | |
1118 | } else if (ret == -EAGAIN) { | |
1119 | prealloc = page_copy_prealloc(src_mm, src_vma, addr); | |
1120 | if (!prealloc) | |
1121 | return -ENOMEM; | |
1122 | } else if (ret) { | |
1123 | VM_WARN_ON_ONCE(1); | |
1124 | } | |
1125 | ||
1126 | /* We've captured and resolved the error. Reset, try again. */ | |
1127 | ret = 0; | |
1128 | ||
1129 | if (addr != end) | |
1130 | goto again; | |
1131 | out: | |
1132 | if (unlikely(prealloc)) | |
1133 | folio_put(prealloc); | |
1134 | return ret; | |
1135 | } | |
1136 | ||
1137 | static inline int | |
1138 | copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
1139 | pud_t *dst_pud, pud_t *src_pud, unsigned long addr, | |
1140 | unsigned long end) | |
1141 | { | |
1142 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
1143 | struct mm_struct *src_mm = src_vma->vm_mm; | |
1144 | pmd_t *src_pmd, *dst_pmd; | |
1145 | unsigned long next; | |
1146 | ||
1147 | dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); | |
1148 | if (!dst_pmd) | |
1149 | return -ENOMEM; | |
1150 | src_pmd = pmd_offset(src_pud, addr); | |
1151 | do { | |
1152 | next = pmd_addr_end(addr, end); | |
1153 | if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) | |
1154 | || pmd_devmap(*src_pmd)) { | |
1155 | int err; | |
1156 | VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma); | |
1157 | err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd, | |
1158 | addr, dst_vma, src_vma); | |
1159 | if (err == -ENOMEM) | |
1160 | return -ENOMEM; | |
1161 | if (!err) | |
1162 | continue; | |
1163 | /* fall through */ | |
1164 | } | |
1165 | if (pmd_none_or_clear_bad(src_pmd)) | |
1166 | continue; | |
1167 | if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd, | |
1168 | addr, next)) | |
1169 | return -ENOMEM; | |
1170 | } while (dst_pmd++, src_pmd++, addr = next, addr != end); | |
1171 | return 0; | |
1172 | } | |
1173 | ||
1174 | static inline int | |
1175 | copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
1176 | p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr, | |
1177 | unsigned long end) | |
1178 | { | |
1179 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
1180 | struct mm_struct *src_mm = src_vma->vm_mm; | |
1181 | pud_t *src_pud, *dst_pud; | |
1182 | unsigned long next; | |
1183 | ||
1184 | dst_pud = pud_alloc(dst_mm, dst_p4d, addr); | |
1185 | if (!dst_pud) | |
1186 | return -ENOMEM; | |
1187 | src_pud = pud_offset(src_p4d, addr); | |
1188 | do { | |
1189 | next = pud_addr_end(addr, end); | |
1190 | if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { | |
1191 | int err; | |
1192 | ||
1193 | VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma); | |
1194 | err = copy_huge_pud(dst_mm, src_mm, | |
1195 | dst_pud, src_pud, addr, src_vma); | |
1196 | if (err == -ENOMEM) | |
1197 | return -ENOMEM; | |
1198 | if (!err) | |
1199 | continue; | |
1200 | /* fall through */ | |
1201 | } | |
1202 | if (pud_none_or_clear_bad(src_pud)) | |
1203 | continue; | |
1204 | if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud, | |
1205 | addr, next)) | |
1206 | return -ENOMEM; | |
1207 | } while (dst_pud++, src_pud++, addr = next, addr != end); | |
1208 | return 0; | |
1209 | } | |
1210 | ||
1211 | static inline int | |
1212 | copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, | |
1213 | pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr, | |
1214 | unsigned long end) | |
1215 | { | |
1216 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
1217 | p4d_t *src_p4d, *dst_p4d; | |
1218 | unsigned long next; | |
1219 | ||
1220 | dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); | |
1221 | if (!dst_p4d) | |
1222 | return -ENOMEM; | |
1223 | src_p4d = p4d_offset(src_pgd, addr); | |
1224 | do { | |
1225 | next = p4d_addr_end(addr, end); | |
1226 | if (p4d_none_or_clear_bad(src_p4d)) | |
1227 | continue; | |
1228 | if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d, | |
1229 | addr, next)) | |
1230 | return -ENOMEM; | |
1231 | } while (dst_p4d++, src_p4d++, addr = next, addr != end); | |
1232 | return 0; | |
1233 | } | |
1234 | ||
1235 | /* | |
1236 | * Return true if the vma needs to copy the pgtable during this fork(). Return | |
1237 | * false when we can speed up fork() by allowing lazy page faults later until | |
1238 | * when the child accesses the memory range. | |
1239 | */ | |
1240 | static bool | |
1241 | vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) | |
1242 | { | |
1243 | /* | |
1244 | * Always copy pgtables when dst_vma has uffd-wp enabled even if it's | |
1245 | * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable | |
1246 | * contains uffd-wp protection information, that's something we can't | |
1247 | * retrieve from page cache, and skip copying will lose those info. | |
1248 | */ | |
1249 | if (userfaultfd_wp(dst_vma)) | |
1250 | return true; | |
1251 | ||
1252 | if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) | |
1253 | return true; | |
1254 | ||
1255 | if (src_vma->anon_vma) | |
1256 | return true; | |
1257 | ||
1258 | /* | |
1259 | * Don't copy ptes where a page fault will fill them correctly. Fork | |
1260 | * becomes much lighter when there are big shared or private readonly | |
1261 | * mappings. The tradeoff is that copy_page_range is more efficient | |
1262 | * than faulting. | |
1263 | */ | |
1264 | return false; | |
1265 | } | |
1266 | ||
1267 | int | |
1268 | copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) | |
1269 | { | |
1270 | pgd_t *src_pgd, *dst_pgd; | |
1271 | unsigned long next; | |
1272 | unsigned long addr = src_vma->vm_start; | |
1273 | unsigned long end = src_vma->vm_end; | |
1274 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
1275 | struct mm_struct *src_mm = src_vma->vm_mm; | |
1276 | struct mmu_notifier_range range; | |
1277 | bool is_cow; | |
1278 | int ret; | |
1279 | ||
1280 | if (!vma_needs_copy(dst_vma, src_vma)) | |
1281 | return 0; | |
1282 | ||
1283 | if (is_vm_hugetlb_page(src_vma)) | |
1284 | return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma); | |
1285 | ||
1286 | if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { | |
1287 | /* | |
1288 | * We do not free on error cases below as remove_vma | |
1289 | * gets called on error from higher level routine | |
1290 | */ | |
1291 | ret = track_pfn_copy(src_vma); | |
1292 | if (ret) | |
1293 | return ret; | |
1294 | } | |
1295 | ||
1296 | /* | |
1297 | * We need to invalidate the secondary MMU mappings only when | |
1298 | * there could be a permission downgrade on the ptes of the | |
1299 | * parent mm. And a permission downgrade will only happen if | |
1300 | * is_cow_mapping() returns true. | |
1301 | */ | |
1302 | is_cow = is_cow_mapping(src_vma->vm_flags); | |
1303 | ||
1304 | if (is_cow) { | |
1305 | mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, | |
1306 | 0, src_mm, addr, end); | |
1307 | mmu_notifier_invalidate_range_start(&range); | |
1308 | /* | |
1309 | * Disabling preemption is not needed for the write side, as | |
1310 | * the read side doesn't spin, but goes to the mmap_lock. | |
1311 | * | |
1312 | * Use the raw variant of the seqcount_t write API to avoid | |
1313 | * lockdep complaining about preemptibility. | |
1314 | */ | |
1315 | vma_assert_write_locked(src_vma); | |
1316 | raw_write_seqcount_begin(&src_mm->write_protect_seq); | |
1317 | } | |
1318 | ||
1319 | ret = 0; | |
1320 | dst_pgd = pgd_offset(dst_mm, addr); | |
1321 | src_pgd = pgd_offset(src_mm, addr); | |
1322 | do { | |
1323 | next = pgd_addr_end(addr, end); | |
1324 | if (pgd_none_or_clear_bad(src_pgd)) | |
1325 | continue; | |
1326 | if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, | |
1327 | addr, next))) { | |
1328 | untrack_pfn_clear(dst_vma); | |
1329 | ret = -ENOMEM; | |
1330 | break; | |
1331 | } | |
1332 | } while (dst_pgd++, src_pgd++, addr = next, addr != end); | |
1333 | ||
1334 | if (is_cow) { | |
1335 | raw_write_seqcount_end(&src_mm->write_protect_seq); | |
1336 | mmu_notifier_invalidate_range_end(&range); | |
1337 | } | |
1338 | return ret; | |
1339 | } | |
1340 | ||
1341 | /* Whether we should zap all COWed (private) pages too */ | |
1342 | static inline bool should_zap_cows(struct zap_details *details) | |
1343 | { | |
1344 | /* By default, zap all pages */ | |
1345 | if (!details) | |
1346 | return true; | |
1347 | ||
1348 | /* Or, we zap COWed pages only if the caller wants to */ | |
1349 | return details->even_cows; | |
1350 | } | |
1351 | ||
1352 | /* Decides whether we should zap this page with the page pointer specified */ | |
1353 | static inline bool should_zap_page(struct zap_details *details, struct page *page) | |
1354 | { | |
1355 | /* If we can make a decision without *page.. */ | |
1356 | if (should_zap_cows(details)) | |
1357 | return true; | |
1358 | ||
1359 | /* E.g. the caller passes NULL for the case of a zero page */ | |
1360 | if (!page) | |
1361 | return true; | |
1362 | ||
1363 | /* Otherwise we should only zap non-anon pages */ | |
1364 | return !PageAnon(page); | |
1365 | } | |
1366 | ||
1367 | static inline bool zap_drop_file_uffd_wp(struct zap_details *details) | |
1368 | { | |
1369 | if (!details) | |
1370 | return false; | |
1371 | ||
1372 | return details->zap_flags & ZAP_FLAG_DROP_MARKER; | |
1373 | } | |
1374 | ||
1375 | /* | |
1376 | * This function makes sure that we'll replace the none pte with an uffd-wp | |
1377 | * swap special pte marker when necessary. Must be with the pgtable lock held. | |
1378 | */ | |
1379 | static inline void | |
1380 | zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, | |
1381 | unsigned long addr, pte_t *pte, | |
1382 | struct zap_details *details, pte_t pteval) | |
1383 | { | |
1384 | /* Zap on anonymous always means dropping everything */ | |
1385 | if (vma_is_anonymous(vma)) | |
1386 | return; | |
1387 | ||
1388 | if (zap_drop_file_uffd_wp(details)) | |
1389 | return; | |
1390 | ||
1391 | pte_install_uffd_wp_if_needed(vma, addr, pte, pteval); | |
1392 | } | |
1393 | ||
1394 | static unsigned long zap_pte_range(struct mmu_gather *tlb, | |
1395 | struct vm_area_struct *vma, pmd_t *pmd, | |
1396 | unsigned long addr, unsigned long end, | |
1397 | struct zap_details *details) | |
1398 | { | |
1399 | struct mm_struct *mm = tlb->mm; | |
1400 | int force_flush = 0; | |
1401 | int rss[NR_MM_COUNTERS]; | |
1402 | spinlock_t *ptl; | |
1403 | pte_t *start_pte; | |
1404 | pte_t *pte; | |
1405 | swp_entry_t entry; | |
1406 | ||
1407 | tlb_change_page_size(tlb, PAGE_SIZE); | |
1408 | init_rss_vec(rss); | |
1409 | start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl); | |
1410 | if (!pte) | |
1411 | return addr; | |
1412 | ||
1413 | flush_tlb_batched_pending(mm); | |
1414 | arch_enter_lazy_mmu_mode(); | |
1415 | do { | |
1416 | pte_t ptent = ptep_get(pte); | |
1417 | struct page *page; | |
1418 | ||
1419 | if (pte_none(ptent)) | |
1420 | continue; | |
1421 | ||
1422 | if (need_resched()) | |
1423 | break; | |
1424 | ||
1425 | if (pte_present(ptent)) { | |
1426 | unsigned int delay_rmap; | |
1427 | ||
1428 | page = vm_normal_page(vma, addr, ptent); | |
1429 | if (unlikely(!should_zap_page(details, page))) | |
1430 | continue; | |
1431 | ptent = ptep_get_and_clear_full(mm, addr, pte, | |
1432 | tlb->fullmm); | |
1433 | arch_check_zapped_pte(vma, ptent); | |
1434 | tlb_remove_tlb_entry(tlb, pte, addr); | |
1435 | zap_install_uffd_wp_if_needed(vma, addr, pte, details, | |
1436 | ptent); | |
1437 | if (unlikely(!page)) { | |
1438 | ksm_might_unmap_zero_page(mm, ptent); | |
1439 | continue; | |
1440 | } | |
1441 | ||
1442 | delay_rmap = 0; | |
1443 | if (!PageAnon(page)) { | |
1444 | if (pte_dirty(ptent)) { | |
1445 | set_page_dirty(page); | |
1446 | if (tlb_delay_rmap(tlb)) { | |
1447 | delay_rmap = 1; | |
1448 | force_flush = 1; | |
1449 | } | |
1450 | } | |
1451 | if (pte_young(ptent) && likely(vma_has_recency(vma))) | |
1452 | mark_page_accessed(page); | |
1453 | } | |
1454 | rss[mm_counter(page)]--; | |
1455 | if (!delay_rmap) { | |
1456 | page_remove_rmap(page, vma, false); | |
1457 | if (unlikely(page_mapcount(page) < 0)) | |
1458 | print_bad_pte(vma, addr, ptent, page); | |
1459 | } | |
1460 | if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) { | |
1461 | force_flush = 1; | |
1462 | addr += PAGE_SIZE; | |
1463 | break; | |
1464 | } | |
1465 | continue; | |
1466 | } | |
1467 | ||
1468 | entry = pte_to_swp_entry(ptent); | |
1469 | if (is_device_private_entry(entry) || | |
1470 | is_device_exclusive_entry(entry)) { | |
1471 | page = pfn_swap_entry_to_page(entry); | |
1472 | if (unlikely(!should_zap_page(details, page))) | |
1473 | continue; | |
1474 | /* | |
1475 | * Both device private/exclusive mappings should only | |
1476 | * work with anonymous page so far, so we don't need to | |
1477 | * consider uffd-wp bit when zap. For more information, | |
1478 | * see zap_install_uffd_wp_if_needed(). | |
1479 | */ | |
1480 | WARN_ON_ONCE(!vma_is_anonymous(vma)); | |
1481 | rss[mm_counter(page)]--; | |
1482 | if (is_device_private_entry(entry)) | |
1483 | page_remove_rmap(page, vma, false); | |
1484 | put_page(page); | |
1485 | } else if (!non_swap_entry(entry)) { | |
1486 | /* Genuine swap entry, hence a private anon page */ | |
1487 | if (!should_zap_cows(details)) | |
1488 | continue; | |
1489 | rss[MM_SWAPENTS]--; | |
1490 | if (unlikely(!free_swap_and_cache(entry))) | |
1491 | print_bad_pte(vma, addr, ptent, NULL); | |
1492 | } else if (is_migration_entry(entry)) { | |
1493 | page = pfn_swap_entry_to_page(entry); | |
1494 | if (!should_zap_page(details, page)) | |
1495 | continue; | |
1496 | rss[mm_counter(page)]--; | |
1497 | } else if (pte_marker_entry_uffd_wp(entry)) { | |
1498 | /* | |
1499 | * For anon: always drop the marker; for file: only | |
1500 | * drop the marker if explicitly requested. | |
1501 | */ | |
1502 | if (!vma_is_anonymous(vma) && | |
1503 | !zap_drop_file_uffd_wp(details)) | |
1504 | continue; | |
1505 | } else if (is_hwpoison_entry(entry) || | |
1506 | is_poisoned_swp_entry(entry)) { | |
1507 | if (!should_zap_cows(details)) | |
1508 | continue; | |
1509 | } else { | |
1510 | /* We should have covered all the swap entry types */ | |
1511 | WARN_ON_ONCE(1); | |
1512 | } | |
1513 | pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); | |
1514 | zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); | |
1515 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
1516 | ||
1517 | add_mm_rss_vec(mm, rss); | |
1518 | arch_leave_lazy_mmu_mode(); | |
1519 | ||
1520 | /* Do the actual TLB flush before dropping ptl */ | |
1521 | if (force_flush) { | |
1522 | tlb_flush_mmu_tlbonly(tlb); | |
1523 | tlb_flush_rmaps(tlb, vma); | |
1524 | } | |
1525 | pte_unmap_unlock(start_pte, ptl); | |
1526 | ||
1527 | /* | |
1528 | * If we forced a TLB flush (either due to running out of | |
1529 | * batch buffers or because we needed to flush dirty TLB | |
1530 | * entries before releasing the ptl), free the batched | |
1531 | * memory too. Come back again if we didn't do everything. | |
1532 | */ | |
1533 | if (force_flush) | |
1534 | tlb_flush_mmu(tlb); | |
1535 | ||
1536 | return addr; | |
1537 | } | |
1538 | ||
1539 | static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, | |
1540 | struct vm_area_struct *vma, pud_t *pud, | |
1541 | unsigned long addr, unsigned long end, | |
1542 | struct zap_details *details) | |
1543 | { | |
1544 | pmd_t *pmd; | |
1545 | unsigned long next; | |
1546 | ||
1547 | pmd = pmd_offset(pud, addr); | |
1548 | do { | |
1549 | next = pmd_addr_end(addr, end); | |
1550 | if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { | |
1551 | if (next - addr != HPAGE_PMD_SIZE) | |
1552 | __split_huge_pmd(vma, pmd, addr, false, NULL); | |
1553 | else if (zap_huge_pmd(tlb, vma, pmd, addr)) { | |
1554 | addr = next; | |
1555 | continue; | |
1556 | } | |
1557 | /* fall through */ | |
1558 | } else if (details && details->single_folio && | |
1559 | folio_test_pmd_mappable(details->single_folio) && | |
1560 | next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) { | |
1561 | spinlock_t *ptl = pmd_lock(tlb->mm, pmd); | |
1562 | /* | |
1563 | * Take and drop THP pmd lock so that we cannot return | |
1564 | * prematurely, while zap_huge_pmd() has cleared *pmd, | |
1565 | * but not yet decremented compound_mapcount(). | |
1566 | */ | |
1567 | spin_unlock(ptl); | |
1568 | } | |
1569 | if (pmd_none(*pmd)) { | |
1570 | addr = next; | |
1571 | continue; | |
1572 | } | |
1573 | addr = zap_pte_range(tlb, vma, pmd, addr, next, details); | |
1574 | if (addr != next) | |
1575 | pmd--; | |
1576 | } while (pmd++, cond_resched(), addr != end); | |
1577 | ||
1578 | return addr; | |
1579 | } | |
1580 | ||
1581 | static inline unsigned long zap_pud_range(struct mmu_gather *tlb, | |
1582 | struct vm_area_struct *vma, p4d_t *p4d, | |
1583 | unsigned long addr, unsigned long end, | |
1584 | struct zap_details *details) | |
1585 | { | |
1586 | pud_t *pud; | |
1587 | unsigned long next; | |
1588 | ||
1589 | pud = pud_offset(p4d, addr); | |
1590 | do { | |
1591 | next = pud_addr_end(addr, end); | |
1592 | if (pud_trans_huge(*pud) || pud_devmap(*pud)) { | |
1593 | if (next - addr != HPAGE_PUD_SIZE) { | |
1594 | mmap_assert_locked(tlb->mm); | |
1595 | split_huge_pud(vma, pud, addr); | |
1596 | } else if (zap_huge_pud(tlb, vma, pud, addr)) | |
1597 | goto next; | |
1598 | /* fall through */ | |
1599 | } | |
1600 | if (pud_none_or_clear_bad(pud)) | |
1601 | continue; | |
1602 | next = zap_pmd_range(tlb, vma, pud, addr, next, details); | |
1603 | next: | |
1604 | cond_resched(); | |
1605 | } while (pud++, addr = next, addr != end); | |
1606 | ||
1607 | return addr; | |
1608 | } | |
1609 | ||
1610 | static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, | |
1611 | struct vm_area_struct *vma, pgd_t *pgd, | |
1612 | unsigned long addr, unsigned long end, | |
1613 | struct zap_details *details) | |
1614 | { | |
1615 | p4d_t *p4d; | |
1616 | unsigned long next; | |
1617 | ||
1618 | p4d = p4d_offset(pgd, addr); | |
1619 | do { | |
1620 | next = p4d_addr_end(addr, end); | |
1621 | if (p4d_none_or_clear_bad(p4d)) | |
1622 | continue; | |
1623 | next = zap_pud_range(tlb, vma, p4d, addr, next, details); | |
1624 | } while (p4d++, addr = next, addr != end); | |
1625 | ||
1626 | return addr; | |
1627 | } | |
1628 | ||
1629 | void unmap_page_range(struct mmu_gather *tlb, | |
1630 | struct vm_area_struct *vma, | |
1631 | unsigned long addr, unsigned long end, | |
1632 | struct zap_details *details) | |
1633 | { | |
1634 | pgd_t *pgd; | |
1635 | unsigned long next; | |
1636 | ||
1637 | BUG_ON(addr >= end); | |
1638 | tlb_start_vma(tlb, vma); | |
1639 | pgd = pgd_offset(vma->vm_mm, addr); | |
1640 | do { | |
1641 | next = pgd_addr_end(addr, end); | |
1642 | if (pgd_none_or_clear_bad(pgd)) | |
1643 | continue; | |
1644 | next = zap_p4d_range(tlb, vma, pgd, addr, next, details); | |
1645 | } while (pgd++, addr = next, addr != end); | |
1646 | tlb_end_vma(tlb, vma); | |
1647 | } | |
1648 | ||
1649 | ||
1650 | static void unmap_single_vma(struct mmu_gather *tlb, | |
1651 | struct vm_area_struct *vma, unsigned long start_addr, | |
1652 | unsigned long end_addr, | |
1653 | struct zap_details *details, bool mm_wr_locked) | |
1654 | { | |
1655 | unsigned long start = max(vma->vm_start, start_addr); | |
1656 | unsigned long end; | |
1657 | ||
1658 | if (start >= vma->vm_end) | |
1659 | return; | |
1660 | end = min(vma->vm_end, end_addr); | |
1661 | if (end <= vma->vm_start) | |
1662 | return; | |
1663 | ||
1664 | if (vma->vm_file) | |
1665 | uprobe_munmap(vma, start, end); | |
1666 | ||
1667 | if (unlikely(vma->vm_flags & VM_PFNMAP)) | |
1668 | untrack_pfn(vma, 0, 0, mm_wr_locked); | |
1669 | ||
1670 | if (start != end) { | |
1671 | if (unlikely(is_vm_hugetlb_page(vma))) { | |
1672 | /* | |
1673 | * It is undesirable to test vma->vm_file as it | |
1674 | * should be non-null for valid hugetlb area. | |
1675 | * However, vm_file will be NULL in the error | |
1676 | * cleanup path of mmap_region. When | |
1677 | * hugetlbfs ->mmap method fails, | |
1678 | * mmap_region() nullifies vma->vm_file | |
1679 | * before calling this function to clean up. | |
1680 | * Since no pte has actually been setup, it is | |
1681 | * safe to do nothing in this case. | |
1682 | */ | |
1683 | if (vma->vm_file) { | |
1684 | zap_flags_t zap_flags = details ? | |
1685 | details->zap_flags : 0; | |
1686 | __unmap_hugepage_range_final(tlb, vma, start, end, | |
1687 | NULL, zap_flags); | |
1688 | } | |
1689 | } else | |
1690 | unmap_page_range(tlb, vma, start, end, details); | |
1691 | } | |
1692 | } | |
1693 | ||
1694 | /** | |
1695 | * unmap_vmas - unmap a range of memory covered by a list of vma's | |
1696 | * @tlb: address of the caller's struct mmu_gather | |
1697 | * @mas: the maple state | |
1698 | * @vma: the starting vma | |
1699 | * @start_addr: virtual address at which to start unmapping | |
1700 | * @end_addr: virtual address at which to end unmapping | |
1701 | * @tree_end: The maximum index to check | |
1702 | * @mm_wr_locked: lock flag | |
1703 | * | |
1704 | * Unmap all pages in the vma list. | |
1705 | * | |
1706 | * Only addresses between `start' and `end' will be unmapped. | |
1707 | * | |
1708 | * The VMA list must be sorted in ascending virtual address order. | |
1709 | * | |
1710 | * unmap_vmas() assumes that the caller will flush the whole unmapped address | |
1711 | * range after unmap_vmas() returns. So the only responsibility here is to | |
1712 | * ensure that any thus-far unmapped pages are flushed before unmap_vmas() | |
1713 | * drops the lock and schedules. | |
1714 | */ | |
1715 | void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas, | |
1716 | struct vm_area_struct *vma, unsigned long start_addr, | |
1717 | unsigned long end_addr, unsigned long tree_end, | |
1718 | bool mm_wr_locked) | |
1719 | { | |
1720 | struct mmu_notifier_range range; | |
1721 | struct zap_details details = { | |
1722 | .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP, | |
1723 | /* Careful - we need to zap private pages too! */ | |
1724 | .even_cows = true, | |
1725 | }; | |
1726 | ||
1727 | mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm, | |
1728 | start_addr, end_addr); | |
1729 | mmu_notifier_invalidate_range_start(&range); | |
1730 | do { | |
1731 | unmap_single_vma(tlb, vma, start_addr, end_addr, &details, | |
1732 | mm_wr_locked); | |
1733 | } while ((vma = mas_find(mas, tree_end - 1)) != NULL); | |
1734 | mmu_notifier_invalidate_range_end(&range); | |
1735 | } | |
1736 | ||
1737 | /** | |
1738 | * zap_page_range_single - remove user pages in a given range | |
1739 | * @vma: vm_area_struct holding the applicable pages | |
1740 | * @address: starting address of pages to zap | |
1741 | * @size: number of bytes to zap | |
1742 | * @details: details of shared cache invalidation | |
1743 | * | |
1744 | * The range must fit into one VMA. | |
1745 | */ | |
1746 | void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, | |
1747 | unsigned long size, struct zap_details *details) | |
1748 | { | |
1749 | const unsigned long end = address + size; | |
1750 | struct mmu_notifier_range range; | |
1751 | struct mmu_gather tlb; | |
1752 | ||
1753 | lru_add_drain(); | |
1754 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, | |
1755 | address, end); | |
1756 | if (is_vm_hugetlb_page(vma)) | |
1757 | adjust_range_if_pmd_sharing_possible(vma, &range.start, | |
1758 | &range.end); | |
1759 | tlb_gather_mmu(&tlb, vma->vm_mm); | |
1760 | update_hiwater_rss(vma->vm_mm); | |
1761 | mmu_notifier_invalidate_range_start(&range); | |
1762 | /* | |
1763 | * unmap 'address-end' not 'range.start-range.end' as range | |
1764 | * could have been expanded for hugetlb pmd sharing. | |
1765 | */ | |
1766 | unmap_single_vma(&tlb, vma, address, end, details, false); | |
1767 | mmu_notifier_invalidate_range_end(&range); | |
1768 | tlb_finish_mmu(&tlb); | |
1769 | } | |
1770 | ||
1771 | /** | |
1772 | * zap_vma_ptes - remove ptes mapping the vma | |
1773 | * @vma: vm_area_struct holding ptes to be zapped | |
1774 | * @address: starting address of pages to zap | |
1775 | * @size: number of bytes to zap | |
1776 | * | |
1777 | * This function only unmaps ptes assigned to VM_PFNMAP vmas. | |
1778 | * | |
1779 | * The entire address range must be fully contained within the vma. | |
1780 | * | |
1781 | */ | |
1782 | void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, | |
1783 | unsigned long size) | |
1784 | { | |
1785 | if (!range_in_vma(vma, address, address + size) || | |
1786 | !(vma->vm_flags & VM_PFNMAP)) | |
1787 | return; | |
1788 | ||
1789 | zap_page_range_single(vma, address, size, NULL); | |
1790 | } | |
1791 | EXPORT_SYMBOL_GPL(zap_vma_ptes); | |
1792 | ||
1793 | static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) | |
1794 | { | |
1795 | pgd_t *pgd; | |
1796 | p4d_t *p4d; | |
1797 | pud_t *pud; | |
1798 | pmd_t *pmd; | |
1799 | ||
1800 | pgd = pgd_offset(mm, addr); | |
1801 | p4d = p4d_alloc(mm, pgd, addr); | |
1802 | if (!p4d) | |
1803 | return NULL; | |
1804 | pud = pud_alloc(mm, p4d, addr); | |
1805 | if (!pud) | |
1806 | return NULL; | |
1807 | pmd = pmd_alloc(mm, pud, addr); | |
1808 | if (!pmd) | |
1809 | return NULL; | |
1810 | ||
1811 | VM_BUG_ON(pmd_trans_huge(*pmd)); | |
1812 | return pmd; | |
1813 | } | |
1814 | ||
1815 | pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, | |
1816 | spinlock_t **ptl) | |
1817 | { | |
1818 | pmd_t *pmd = walk_to_pmd(mm, addr); | |
1819 | ||
1820 | if (!pmd) | |
1821 | return NULL; | |
1822 | return pte_alloc_map_lock(mm, pmd, addr, ptl); | |
1823 | } | |
1824 | ||
1825 | static int validate_page_before_insert(struct page *page) | |
1826 | { | |
1827 | if (PageAnon(page) || PageSlab(page) || page_has_type(page)) | |
1828 | return -EINVAL; | |
1829 | flush_dcache_page(page); | |
1830 | return 0; | |
1831 | } | |
1832 | ||
1833 | static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte, | |
1834 | unsigned long addr, struct page *page, pgprot_t prot) | |
1835 | { | |
1836 | if (!pte_none(ptep_get(pte))) | |
1837 | return -EBUSY; | |
1838 | /* Ok, finally just insert the thing.. */ | |
1839 | get_page(page); | |
1840 | inc_mm_counter(vma->vm_mm, mm_counter_file(page)); | |
1841 | page_add_file_rmap(page, vma, false); | |
1842 | set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot)); | |
1843 | return 0; | |
1844 | } | |
1845 | ||
1846 | /* | |
1847 | * This is the old fallback for page remapping. | |
1848 | * | |
1849 | * For historical reasons, it only allows reserved pages. Only | |
1850 | * old drivers should use this, and they needed to mark their | |
1851 | * pages reserved for the old functions anyway. | |
1852 | */ | |
1853 | static int insert_page(struct vm_area_struct *vma, unsigned long addr, | |
1854 | struct page *page, pgprot_t prot) | |
1855 | { | |
1856 | int retval; | |
1857 | pte_t *pte; | |
1858 | spinlock_t *ptl; | |
1859 | ||
1860 | retval = validate_page_before_insert(page); | |
1861 | if (retval) | |
1862 | goto out; | |
1863 | retval = -ENOMEM; | |
1864 | pte = get_locked_pte(vma->vm_mm, addr, &ptl); | |
1865 | if (!pte) | |
1866 | goto out; | |
1867 | retval = insert_page_into_pte_locked(vma, pte, addr, page, prot); | |
1868 | pte_unmap_unlock(pte, ptl); | |
1869 | out: | |
1870 | return retval; | |
1871 | } | |
1872 | ||
1873 | static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte, | |
1874 | unsigned long addr, struct page *page, pgprot_t prot) | |
1875 | { | |
1876 | int err; | |
1877 | ||
1878 | if (!page_count(page)) | |
1879 | return -EINVAL; | |
1880 | err = validate_page_before_insert(page); | |
1881 | if (err) | |
1882 | return err; | |
1883 | return insert_page_into_pte_locked(vma, pte, addr, page, prot); | |
1884 | } | |
1885 | ||
1886 | /* insert_pages() amortizes the cost of spinlock operations | |
1887 | * when inserting pages in a loop. | |
1888 | */ | |
1889 | static int insert_pages(struct vm_area_struct *vma, unsigned long addr, | |
1890 | struct page **pages, unsigned long *num, pgprot_t prot) | |
1891 | { | |
1892 | pmd_t *pmd = NULL; | |
1893 | pte_t *start_pte, *pte; | |
1894 | spinlock_t *pte_lock; | |
1895 | struct mm_struct *const mm = vma->vm_mm; | |
1896 | unsigned long curr_page_idx = 0; | |
1897 | unsigned long remaining_pages_total = *num; | |
1898 | unsigned long pages_to_write_in_pmd; | |
1899 | int ret; | |
1900 | more: | |
1901 | ret = -EFAULT; | |
1902 | pmd = walk_to_pmd(mm, addr); | |
1903 | if (!pmd) | |
1904 | goto out; | |
1905 | ||
1906 | pages_to_write_in_pmd = min_t(unsigned long, | |
1907 | remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); | |
1908 | ||
1909 | /* Allocate the PTE if necessary; takes PMD lock once only. */ | |
1910 | ret = -ENOMEM; | |
1911 | if (pte_alloc(mm, pmd)) | |
1912 | goto out; | |
1913 | ||
1914 | while (pages_to_write_in_pmd) { | |
1915 | int pte_idx = 0; | |
1916 | const int batch_size = min_t(int, pages_to_write_in_pmd, 8); | |
1917 | ||
1918 | start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock); | |
1919 | if (!start_pte) { | |
1920 | ret = -EFAULT; | |
1921 | goto out; | |
1922 | } | |
1923 | for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { | |
1924 | int err = insert_page_in_batch_locked(vma, pte, | |
1925 | addr, pages[curr_page_idx], prot); | |
1926 | if (unlikely(err)) { | |
1927 | pte_unmap_unlock(start_pte, pte_lock); | |
1928 | ret = err; | |
1929 | remaining_pages_total -= pte_idx; | |
1930 | goto out; | |
1931 | } | |
1932 | addr += PAGE_SIZE; | |
1933 | ++curr_page_idx; | |
1934 | } | |
1935 | pte_unmap_unlock(start_pte, pte_lock); | |
1936 | pages_to_write_in_pmd -= batch_size; | |
1937 | remaining_pages_total -= batch_size; | |
1938 | } | |
1939 | if (remaining_pages_total) | |
1940 | goto more; | |
1941 | ret = 0; | |
1942 | out: | |
1943 | *num = remaining_pages_total; | |
1944 | return ret; | |
1945 | } | |
1946 | ||
1947 | /** | |
1948 | * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. | |
1949 | * @vma: user vma to map to | |
1950 | * @addr: target start user address of these pages | |
1951 | * @pages: source kernel pages | |
1952 | * @num: in: number of pages to map. out: number of pages that were *not* | |
1953 | * mapped. (0 means all pages were successfully mapped). | |
1954 | * | |
1955 | * Preferred over vm_insert_page() when inserting multiple pages. | |
1956 | * | |
1957 | * In case of error, we may have mapped a subset of the provided | |
1958 | * pages. It is the caller's responsibility to account for this case. | |
1959 | * | |
1960 | * The same restrictions apply as in vm_insert_page(). | |
1961 | */ | |
1962 | int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, | |
1963 | struct page **pages, unsigned long *num) | |
1964 | { | |
1965 | const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; | |
1966 | ||
1967 | if (addr < vma->vm_start || end_addr >= vma->vm_end) | |
1968 | return -EFAULT; | |
1969 | if (!(vma->vm_flags & VM_MIXEDMAP)) { | |
1970 | BUG_ON(mmap_read_trylock(vma->vm_mm)); | |
1971 | BUG_ON(vma->vm_flags & VM_PFNMAP); | |
1972 | vm_flags_set(vma, VM_MIXEDMAP); | |
1973 | } | |
1974 | /* Defer page refcount checking till we're about to map that page. */ | |
1975 | return insert_pages(vma, addr, pages, num, vma->vm_page_prot); | |
1976 | } | |
1977 | EXPORT_SYMBOL(vm_insert_pages); | |
1978 | ||
1979 | /** | |
1980 | * vm_insert_page - insert single page into user vma | |
1981 | * @vma: user vma to map to | |
1982 | * @addr: target user address of this page | |
1983 | * @page: source kernel page | |
1984 | * | |
1985 | * This allows drivers to insert individual pages they've allocated | |
1986 | * into a user vma. | |
1987 | * | |
1988 | * The page has to be a nice clean _individual_ kernel allocation. | |
1989 | * If you allocate a compound page, you need to have marked it as | |
1990 | * such (__GFP_COMP), or manually just split the page up yourself | |
1991 | * (see split_page()). | |
1992 | * | |
1993 | * NOTE! Traditionally this was done with "remap_pfn_range()" which | |
1994 | * took an arbitrary page protection parameter. This doesn't allow | |
1995 | * that. Your vma protection will have to be set up correctly, which | |
1996 | * means that if you want a shared writable mapping, you'd better | |
1997 | * ask for a shared writable mapping! | |
1998 | * | |
1999 | * The page does not need to be reserved. | |
2000 | * | |
2001 | * Usually this function is called from f_op->mmap() handler | |
2002 | * under mm->mmap_lock write-lock, so it can change vma->vm_flags. | |
2003 | * Caller must set VM_MIXEDMAP on vma if it wants to call this | |
2004 | * function from other places, for example from page-fault handler. | |
2005 | * | |
2006 | * Return: %0 on success, negative error code otherwise. | |
2007 | */ | |
2008 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, | |
2009 | struct page *page) | |
2010 | { | |
2011 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
2012 | return -EFAULT; | |
2013 | if (!page_count(page)) | |
2014 | return -EINVAL; | |
2015 | if (!(vma->vm_flags & VM_MIXEDMAP)) { | |
2016 | BUG_ON(mmap_read_trylock(vma->vm_mm)); | |
2017 | BUG_ON(vma->vm_flags & VM_PFNMAP); | |
2018 | vm_flags_set(vma, VM_MIXEDMAP); | |
2019 | } | |
2020 | return insert_page(vma, addr, page, vma->vm_page_prot); | |
2021 | } | |
2022 | EXPORT_SYMBOL(vm_insert_page); | |
2023 | ||
2024 | /* | |
2025 | * __vm_map_pages - maps range of kernel pages into user vma | |
2026 | * @vma: user vma to map to | |
2027 | * @pages: pointer to array of source kernel pages | |
2028 | * @num: number of pages in page array | |
2029 | * @offset: user's requested vm_pgoff | |
2030 | * | |
2031 | * This allows drivers to map range of kernel pages into a user vma. | |
2032 | * | |
2033 | * Return: 0 on success and error code otherwise. | |
2034 | */ | |
2035 | static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, | |
2036 | unsigned long num, unsigned long offset) | |
2037 | { | |
2038 | unsigned long count = vma_pages(vma); | |
2039 | unsigned long uaddr = vma->vm_start; | |
2040 | int ret, i; | |
2041 | ||
2042 | /* Fail if the user requested offset is beyond the end of the object */ | |
2043 | if (offset >= num) | |
2044 | return -ENXIO; | |
2045 | ||
2046 | /* Fail if the user requested size exceeds available object size */ | |
2047 | if (count > num - offset) | |
2048 | return -ENXIO; | |
2049 | ||
2050 | for (i = 0; i < count; i++) { | |
2051 | ret = vm_insert_page(vma, uaddr, pages[offset + i]); | |
2052 | if (ret < 0) | |
2053 | return ret; | |
2054 | uaddr += PAGE_SIZE; | |
2055 | } | |
2056 | ||
2057 | return 0; | |
2058 | } | |
2059 | ||
2060 | /** | |
2061 | * vm_map_pages - maps range of kernel pages starts with non zero offset | |
2062 | * @vma: user vma to map to | |
2063 | * @pages: pointer to array of source kernel pages | |
2064 | * @num: number of pages in page array | |
2065 | * | |
2066 | * Maps an object consisting of @num pages, catering for the user's | |
2067 | * requested vm_pgoff | |
2068 | * | |
2069 | * If we fail to insert any page into the vma, the function will return | |
2070 | * immediately leaving any previously inserted pages present. Callers | |
2071 | * from the mmap handler may immediately return the error as their caller | |
2072 | * will destroy the vma, removing any successfully inserted pages. Other | |
2073 | * callers should make their own arrangements for calling unmap_region(). | |
2074 | * | |
2075 | * Context: Process context. Called by mmap handlers. | |
2076 | * Return: 0 on success and error code otherwise. | |
2077 | */ | |
2078 | int vm_map_pages(struct vm_area_struct *vma, struct page **pages, | |
2079 | unsigned long num) | |
2080 | { | |
2081 | return __vm_map_pages(vma, pages, num, vma->vm_pgoff); | |
2082 | } | |
2083 | EXPORT_SYMBOL(vm_map_pages); | |
2084 | ||
2085 | /** | |
2086 | * vm_map_pages_zero - map range of kernel pages starts with zero offset | |
2087 | * @vma: user vma to map to | |
2088 | * @pages: pointer to array of source kernel pages | |
2089 | * @num: number of pages in page array | |
2090 | * | |
2091 | * Similar to vm_map_pages(), except that it explicitly sets the offset | |
2092 | * to 0. This function is intended for the drivers that did not consider | |
2093 | * vm_pgoff. | |
2094 | * | |
2095 | * Context: Process context. Called by mmap handlers. | |
2096 | * Return: 0 on success and error code otherwise. | |
2097 | */ | |
2098 | int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, | |
2099 | unsigned long num) | |
2100 | { | |
2101 | return __vm_map_pages(vma, pages, num, 0); | |
2102 | } | |
2103 | EXPORT_SYMBOL(vm_map_pages_zero); | |
2104 | ||
2105 | static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, | |
2106 | pfn_t pfn, pgprot_t prot, bool mkwrite) | |
2107 | { | |
2108 | struct mm_struct *mm = vma->vm_mm; | |
2109 | pte_t *pte, entry; | |
2110 | spinlock_t *ptl; | |
2111 | ||
2112 | pte = get_locked_pte(mm, addr, &ptl); | |
2113 | if (!pte) | |
2114 | return VM_FAULT_OOM; | |
2115 | entry = ptep_get(pte); | |
2116 | if (!pte_none(entry)) { | |
2117 | if (mkwrite) { | |
2118 | /* | |
2119 | * For read faults on private mappings the PFN passed | |
2120 | * in may not match the PFN we have mapped if the | |
2121 | * mapped PFN is a writeable COW page. In the mkwrite | |
2122 | * case we are creating a writable PTE for a shared | |
2123 | * mapping and we expect the PFNs to match. If they | |
2124 | * don't match, we are likely racing with block | |
2125 | * allocation and mapping invalidation so just skip the | |
2126 | * update. | |
2127 | */ | |
2128 | if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) { | |
2129 | WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry))); | |
2130 | goto out_unlock; | |
2131 | } | |
2132 | entry = pte_mkyoung(entry); | |
2133 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
2134 | if (ptep_set_access_flags(vma, addr, pte, entry, 1)) | |
2135 | update_mmu_cache(vma, addr, pte); | |
2136 | } | |
2137 | goto out_unlock; | |
2138 | } | |
2139 | ||
2140 | /* Ok, finally just insert the thing.. */ | |
2141 | if (pfn_t_devmap(pfn)) | |
2142 | entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); | |
2143 | else | |
2144 | entry = pte_mkspecial(pfn_t_pte(pfn, prot)); | |
2145 | ||
2146 | if (mkwrite) { | |
2147 | entry = pte_mkyoung(entry); | |
2148 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
2149 | } | |
2150 | ||
2151 | set_pte_at(mm, addr, pte, entry); | |
2152 | update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ | |
2153 | ||
2154 | out_unlock: | |
2155 | pte_unmap_unlock(pte, ptl); | |
2156 | return VM_FAULT_NOPAGE; | |
2157 | } | |
2158 | ||
2159 | /** | |
2160 | * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot | |
2161 | * @vma: user vma to map to | |
2162 | * @addr: target user address of this page | |
2163 | * @pfn: source kernel pfn | |
2164 | * @pgprot: pgprot flags for the inserted page | |
2165 | * | |
2166 | * This is exactly like vmf_insert_pfn(), except that it allows drivers | |
2167 | * to override pgprot on a per-page basis. | |
2168 | * | |
2169 | * This only makes sense for IO mappings, and it makes no sense for | |
2170 | * COW mappings. In general, using multiple vmas is preferable; | |
2171 | * vmf_insert_pfn_prot should only be used if using multiple VMAs is | |
2172 | * impractical. | |
2173 | * | |
2174 | * pgprot typically only differs from @vma->vm_page_prot when drivers set | |
2175 | * caching- and encryption bits different than those of @vma->vm_page_prot, | |
2176 | * because the caching- or encryption mode may not be known at mmap() time. | |
2177 | * | |
2178 | * This is ok as long as @vma->vm_page_prot is not used by the core vm | |
2179 | * to set caching and encryption bits for those vmas (except for COW pages). | |
2180 | * This is ensured by core vm only modifying these page table entries using | |
2181 | * functions that don't touch caching- or encryption bits, using pte_modify() | |
2182 | * if needed. (See for example mprotect()). | |
2183 | * | |
2184 | * Also when new page-table entries are created, this is only done using the | |
2185 | * fault() callback, and never using the value of vma->vm_page_prot, | |
2186 | * except for page-table entries that point to anonymous pages as the result | |
2187 | * of COW. | |
2188 | * | |
2189 | * Context: Process context. May allocate using %GFP_KERNEL. | |
2190 | * Return: vm_fault_t value. | |
2191 | */ | |
2192 | vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, | |
2193 | unsigned long pfn, pgprot_t pgprot) | |
2194 | { | |
2195 | /* | |
2196 | * Technically, architectures with pte_special can avoid all these | |
2197 | * restrictions (same for remap_pfn_range). However we would like | |
2198 | * consistency in testing and feature parity among all, so we should | |
2199 | * try to keep these invariants in place for everybody. | |
2200 | */ | |
2201 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
2202 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
2203 | (VM_PFNMAP|VM_MIXEDMAP)); | |
2204 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
2205 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); | |
2206 | ||
2207 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
2208 | return VM_FAULT_SIGBUS; | |
2209 | ||
2210 | if (!pfn_modify_allowed(pfn, pgprot)) | |
2211 | return VM_FAULT_SIGBUS; | |
2212 | ||
2213 | track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); | |
2214 | ||
2215 | return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, | |
2216 | false); | |
2217 | } | |
2218 | EXPORT_SYMBOL(vmf_insert_pfn_prot); | |
2219 | ||
2220 | /** | |
2221 | * vmf_insert_pfn - insert single pfn into user vma | |
2222 | * @vma: user vma to map to | |
2223 | * @addr: target user address of this page | |
2224 | * @pfn: source kernel pfn | |
2225 | * | |
2226 | * Similar to vm_insert_page, this allows drivers to insert individual pages | |
2227 | * they've allocated into a user vma. Same comments apply. | |
2228 | * | |
2229 | * This function should only be called from a vm_ops->fault handler, and | |
2230 | * in that case the handler should return the result of this function. | |
2231 | * | |
2232 | * vma cannot be a COW mapping. | |
2233 | * | |
2234 | * As this is called only for pages that do not currently exist, we | |
2235 | * do not need to flush old virtual caches or the TLB. | |
2236 | * | |
2237 | * Context: Process context. May allocate using %GFP_KERNEL. | |
2238 | * Return: vm_fault_t value. | |
2239 | */ | |
2240 | vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, | |
2241 | unsigned long pfn) | |
2242 | { | |
2243 | return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); | |
2244 | } | |
2245 | EXPORT_SYMBOL(vmf_insert_pfn); | |
2246 | ||
2247 | static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) | |
2248 | { | |
2249 | /* these checks mirror the abort conditions in vm_normal_page */ | |
2250 | if (vma->vm_flags & VM_MIXEDMAP) | |
2251 | return true; | |
2252 | if (pfn_t_devmap(pfn)) | |
2253 | return true; | |
2254 | if (pfn_t_special(pfn)) | |
2255 | return true; | |
2256 | if (is_zero_pfn(pfn_t_to_pfn(pfn))) | |
2257 | return true; | |
2258 | return false; | |
2259 | } | |
2260 | ||
2261 | static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, | |
2262 | unsigned long addr, pfn_t pfn, bool mkwrite) | |
2263 | { | |
2264 | pgprot_t pgprot = vma->vm_page_prot; | |
2265 | int err; | |
2266 | ||
2267 | BUG_ON(!vm_mixed_ok(vma, pfn)); | |
2268 | ||
2269 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
2270 | return VM_FAULT_SIGBUS; | |
2271 | ||
2272 | track_pfn_insert(vma, &pgprot, pfn); | |
2273 | ||
2274 | if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot)) | |
2275 | return VM_FAULT_SIGBUS; | |
2276 | ||
2277 | /* | |
2278 | * If we don't have pte special, then we have to use the pfn_valid() | |
2279 | * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* | |
2280 | * refcount the page if pfn_valid is true (hence insert_page rather | |
2281 | * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP | |
2282 | * without pte special, it would there be refcounted as a normal page. | |
2283 | */ | |
2284 | if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && | |
2285 | !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { | |
2286 | struct page *page; | |
2287 | ||
2288 | /* | |
2289 | * At this point we are committed to insert_page() | |
2290 | * regardless of whether the caller specified flags that | |
2291 | * result in pfn_t_has_page() == false. | |
2292 | */ | |
2293 | page = pfn_to_page(pfn_t_to_pfn(pfn)); | |
2294 | err = insert_page(vma, addr, page, pgprot); | |
2295 | } else { | |
2296 | return insert_pfn(vma, addr, pfn, pgprot, mkwrite); | |
2297 | } | |
2298 | ||
2299 | if (err == -ENOMEM) | |
2300 | return VM_FAULT_OOM; | |
2301 | if (err < 0 && err != -EBUSY) | |
2302 | return VM_FAULT_SIGBUS; | |
2303 | ||
2304 | return VM_FAULT_NOPAGE; | |
2305 | } | |
2306 | ||
2307 | vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, | |
2308 | pfn_t pfn) | |
2309 | { | |
2310 | return __vm_insert_mixed(vma, addr, pfn, false); | |
2311 | } | |
2312 | EXPORT_SYMBOL(vmf_insert_mixed); | |
2313 | ||
2314 | /* | |
2315 | * If the insertion of PTE failed because someone else already added a | |
2316 | * different entry in the mean time, we treat that as success as we assume | |
2317 | * the same entry was actually inserted. | |
2318 | */ | |
2319 | vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, | |
2320 | unsigned long addr, pfn_t pfn) | |
2321 | { | |
2322 | return __vm_insert_mixed(vma, addr, pfn, true); | |
2323 | } | |
2324 | EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); | |
2325 | ||
2326 | /* | |
2327 | * maps a range of physical memory into the requested pages. the old | |
2328 | * mappings are removed. any references to nonexistent pages results | |
2329 | * in null mappings (currently treated as "copy-on-access") | |
2330 | */ | |
2331 | static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, | |
2332 | unsigned long addr, unsigned long end, | |
2333 | unsigned long pfn, pgprot_t prot) | |
2334 | { | |
2335 | pte_t *pte, *mapped_pte; | |
2336 | spinlock_t *ptl; | |
2337 | int err = 0; | |
2338 | ||
2339 | mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); | |
2340 | if (!pte) | |
2341 | return -ENOMEM; | |
2342 | arch_enter_lazy_mmu_mode(); | |
2343 | do { | |
2344 | BUG_ON(!pte_none(ptep_get(pte))); | |
2345 | if (!pfn_modify_allowed(pfn, prot)) { | |
2346 | err = -EACCES; | |
2347 | break; | |
2348 | } | |
2349 | set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); | |
2350 | pfn++; | |
2351 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
2352 | arch_leave_lazy_mmu_mode(); | |
2353 | pte_unmap_unlock(mapped_pte, ptl); | |
2354 | return err; | |
2355 | } | |
2356 | ||
2357 | static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, | |
2358 | unsigned long addr, unsigned long end, | |
2359 | unsigned long pfn, pgprot_t prot) | |
2360 | { | |
2361 | pmd_t *pmd; | |
2362 | unsigned long next; | |
2363 | int err; | |
2364 | ||
2365 | pfn -= addr >> PAGE_SHIFT; | |
2366 | pmd = pmd_alloc(mm, pud, addr); | |
2367 | if (!pmd) | |
2368 | return -ENOMEM; | |
2369 | VM_BUG_ON(pmd_trans_huge(*pmd)); | |
2370 | do { | |
2371 | next = pmd_addr_end(addr, end); | |
2372 | err = remap_pte_range(mm, pmd, addr, next, | |
2373 | pfn + (addr >> PAGE_SHIFT), prot); | |
2374 | if (err) | |
2375 | return err; | |
2376 | } while (pmd++, addr = next, addr != end); | |
2377 | return 0; | |
2378 | } | |
2379 | ||
2380 | static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, | |
2381 | unsigned long addr, unsigned long end, | |
2382 | unsigned long pfn, pgprot_t prot) | |
2383 | { | |
2384 | pud_t *pud; | |
2385 | unsigned long next; | |
2386 | int err; | |
2387 | ||
2388 | pfn -= addr >> PAGE_SHIFT; | |
2389 | pud = pud_alloc(mm, p4d, addr); | |
2390 | if (!pud) | |
2391 | return -ENOMEM; | |
2392 | do { | |
2393 | next = pud_addr_end(addr, end); | |
2394 | err = remap_pmd_range(mm, pud, addr, next, | |
2395 | pfn + (addr >> PAGE_SHIFT), prot); | |
2396 | if (err) | |
2397 | return err; | |
2398 | } while (pud++, addr = next, addr != end); | |
2399 | return 0; | |
2400 | } | |
2401 | ||
2402 | static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, | |
2403 | unsigned long addr, unsigned long end, | |
2404 | unsigned long pfn, pgprot_t prot) | |
2405 | { | |
2406 | p4d_t *p4d; | |
2407 | unsigned long next; | |
2408 | int err; | |
2409 | ||
2410 | pfn -= addr >> PAGE_SHIFT; | |
2411 | p4d = p4d_alloc(mm, pgd, addr); | |
2412 | if (!p4d) | |
2413 | return -ENOMEM; | |
2414 | do { | |
2415 | next = p4d_addr_end(addr, end); | |
2416 | err = remap_pud_range(mm, p4d, addr, next, | |
2417 | pfn + (addr >> PAGE_SHIFT), prot); | |
2418 | if (err) | |
2419 | return err; | |
2420 | } while (p4d++, addr = next, addr != end); | |
2421 | return 0; | |
2422 | } | |
2423 | ||
2424 | /* | |
2425 | * Variant of remap_pfn_range that does not call track_pfn_remap. The caller | |
2426 | * must have pre-validated the caching bits of the pgprot_t. | |
2427 | */ | |
2428 | int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, | |
2429 | unsigned long pfn, unsigned long size, pgprot_t prot) | |
2430 | { | |
2431 | pgd_t *pgd; | |
2432 | unsigned long next; | |
2433 | unsigned long end = addr + PAGE_ALIGN(size); | |
2434 | struct mm_struct *mm = vma->vm_mm; | |
2435 | int err; | |
2436 | ||
2437 | if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) | |
2438 | return -EINVAL; | |
2439 | ||
2440 | /* | |
2441 | * Physically remapped pages are special. Tell the | |
2442 | * rest of the world about it: | |
2443 | * VM_IO tells people not to look at these pages | |
2444 | * (accesses can have side effects). | |
2445 | * VM_PFNMAP tells the core MM that the base pages are just | |
2446 | * raw PFN mappings, and do not have a "struct page" associated | |
2447 | * with them. | |
2448 | * VM_DONTEXPAND | |
2449 | * Disable vma merging and expanding with mremap(). | |
2450 | * VM_DONTDUMP | |
2451 | * Omit vma from core dump, even when VM_IO turned off. | |
2452 | * | |
2453 | * There's a horrible special case to handle copy-on-write | |
2454 | * behaviour that some programs depend on. We mark the "original" | |
2455 | * un-COW'ed pages by matching them up with "vma->vm_pgoff". | |
2456 | * See vm_normal_page() for details. | |
2457 | */ | |
2458 | if (is_cow_mapping(vma->vm_flags)) { | |
2459 | if (addr != vma->vm_start || end != vma->vm_end) | |
2460 | return -EINVAL; | |
2461 | vma->vm_pgoff = pfn; | |
2462 | } | |
2463 | ||
2464 | vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); | |
2465 | ||
2466 | BUG_ON(addr >= end); | |
2467 | pfn -= addr >> PAGE_SHIFT; | |
2468 | pgd = pgd_offset(mm, addr); | |
2469 | flush_cache_range(vma, addr, end); | |
2470 | do { | |
2471 | next = pgd_addr_end(addr, end); | |
2472 | err = remap_p4d_range(mm, pgd, addr, next, | |
2473 | pfn + (addr >> PAGE_SHIFT), prot); | |
2474 | if (err) | |
2475 | return err; | |
2476 | } while (pgd++, addr = next, addr != end); | |
2477 | ||
2478 | return 0; | |
2479 | } | |
2480 | ||
2481 | /** | |
2482 | * remap_pfn_range - remap kernel memory to userspace | |
2483 | * @vma: user vma to map to | |
2484 | * @addr: target page aligned user address to start at | |
2485 | * @pfn: page frame number of kernel physical memory address | |
2486 | * @size: size of mapping area | |
2487 | * @prot: page protection flags for this mapping | |
2488 | * | |
2489 | * Note: this is only safe if the mm semaphore is held when called. | |
2490 | * | |
2491 | * Return: %0 on success, negative error code otherwise. | |
2492 | */ | |
2493 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, | |
2494 | unsigned long pfn, unsigned long size, pgprot_t prot) | |
2495 | { | |
2496 | int err; | |
2497 | ||
2498 | err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); | |
2499 | if (err) | |
2500 | return -EINVAL; | |
2501 | ||
2502 | err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); | |
2503 | if (err) | |
2504 | untrack_pfn(vma, pfn, PAGE_ALIGN(size), true); | |
2505 | return err; | |
2506 | } | |
2507 | EXPORT_SYMBOL(remap_pfn_range); | |
2508 | ||
2509 | /** | |
2510 | * vm_iomap_memory - remap memory to userspace | |
2511 | * @vma: user vma to map to | |
2512 | * @start: start of the physical memory to be mapped | |
2513 | * @len: size of area | |
2514 | * | |
2515 | * This is a simplified io_remap_pfn_range() for common driver use. The | |
2516 | * driver just needs to give us the physical memory range to be mapped, | |
2517 | * we'll figure out the rest from the vma information. | |
2518 | * | |
2519 | * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get | |
2520 | * whatever write-combining details or similar. | |
2521 | * | |
2522 | * Return: %0 on success, negative error code otherwise. | |
2523 | */ | |
2524 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) | |
2525 | { | |
2526 | unsigned long vm_len, pfn, pages; | |
2527 | ||
2528 | /* Check that the physical memory area passed in looks valid */ | |
2529 | if (start + len < start) | |
2530 | return -EINVAL; | |
2531 | /* | |
2532 | * You *really* shouldn't map things that aren't page-aligned, | |
2533 | * but we've historically allowed it because IO memory might | |
2534 | * just have smaller alignment. | |
2535 | */ | |
2536 | len += start & ~PAGE_MASK; | |
2537 | pfn = start >> PAGE_SHIFT; | |
2538 | pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; | |
2539 | if (pfn + pages < pfn) | |
2540 | return -EINVAL; | |
2541 | ||
2542 | /* We start the mapping 'vm_pgoff' pages into the area */ | |
2543 | if (vma->vm_pgoff > pages) | |
2544 | return -EINVAL; | |
2545 | pfn += vma->vm_pgoff; | |
2546 | pages -= vma->vm_pgoff; | |
2547 | ||
2548 | /* Can we fit all of the mapping? */ | |
2549 | vm_len = vma->vm_end - vma->vm_start; | |
2550 | if (vm_len >> PAGE_SHIFT > pages) | |
2551 | return -EINVAL; | |
2552 | ||
2553 | /* Ok, let it rip */ | |
2554 | return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); | |
2555 | } | |
2556 | EXPORT_SYMBOL(vm_iomap_memory); | |
2557 | ||
2558 | static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, | |
2559 | unsigned long addr, unsigned long end, | |
2560 | pte_fn_t fn, void *data, bool create, | |
2561 | pgtbl_mod_mask *mask) | |
2562 | { | |
2563 | pte_t *pte, *mapped_pte; | |
2564 | int err = 0; | |
2565 | spinlock_t *ptl; | |
2566 | ||
2567 | if (create) { | |
2568 | mapped_pte = pte = (mm == &init_mm) ? | |
2569 | pte_alloc_kernel_track(pmd, addr, mask) : | |
2570 | pte_alloc_map_lock(mm, pmd, addr, &ptl); | |
2571 | if (!pte) | |
2572 | return -ENOMEM; | |
2573 | } else { | |
2574 | mapped_pte = pte = (mm == &init_mm) ? | |
2575 | pte_offset_kernel(pmd, addr) : | |
2576 | pte_offset_map_lock(mm, pmd, addr, &ptl); | |
2577 | if (!pte) | |
2578 | return -EINVAL; | |
2579 | } | |
2580 | ||
2581 | arch_enter_lazy_mmu_mode(); | |
2582 | ||
2583 | if (fn) { | |
2584 | do { | |
2585 | if (create || !pte_none(ptep_get(pte))) { | |
2586 | err = fn(pte++, addr, data); | |
2587 | if (err) | |
2588 | break; | |
2589 | } | |
2590 | } while (addr += PAGE_SIZE, addr != end); | |
2591 | } | |
2592 | *mask |= PGTBL_PTE_MODIFIED; | |
2593 | ||
2594 | arch_leave_lazy_mmu_mode(); | |
2595 | ||
2596 | if (mm != &init_mm) | |
2597 | pte_unmap_unlock(mapped_pte, ptl); | |
2598 | return err; | |
2599 | } | |
2600 | ||
2601 | static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, | |
2602 | unsigned long addr, unsigned long end, | |
2603 | pte_fn_t fn, void *data, bool create, | |
2604 | pgtbl_mod_mask *mask) | |
2605 | { | |
2606 | pmd_t *pmd; | |
2607 | unsigned long next; | |
2608 | int err = 0; | |
2609 | ||
2610 | BUG_ON(pud_huge(*pud)); | |
2611 | ||
2612 | if (create) { | |
2613 | pmd = pmd_alloc_track(mm, pud, addr, mask); | |
2614 | if (!pmd) | |
2615 | return -ENOMEM; | |
2616 | } else { | |
2617 | pmd = pmd_offset(pud, addr); | |
2618 | } | |
2619 | do { | |
2620 | next = pmd_addr_end(addr, end); | |
2621 | if (pmd_none(*pmd) && !create) | |
2622 | continue; | |
2623 | if (WARN_ON_ONCE(pmd_leaf(*pmd))) | |
2624 | return -EINVAL; | |
2625 | if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { | |
2626 | if (!create) | |
2627 | continue; | |
2628 | pmd_clear_bad(pmd); | |
2629 | } | |
2630 | err = apply_to_pte_range(mm, pmd, addr, next, | |
2631 | fn, data, create, mask); | |
2632 | if (err) | |
2633 | break; | |
2634 | } while (pmd++, addr = next, addr != end); | |
2635 | ||
2636 | return err; | |
2637 | } | |
2638 | ||
2639 | static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, | |
2640 | unsigned long addr, unsigned long end, | |
2641 | pte_fn_t fn, void *data, bool create, | |
2642 | pgtbl_mod_mask *mask) | |
2643 | { | |
2644 | pud_t *pud; | |
2645 | unsigned long next; | |
2646 | int err = 0; | |
2647 | ||
2648 | if (create) { | |
2649 | pud = pud_alloc_track(mm, p4d, addr, mask); | |
2650 | if (!pud) | |
2651 | return -ENOMEM; | |
2652 | } else { | |
2653 | pud = pud_offset(p4d, addr); | |
2654 | } | |
2655 | do { | |
2656 | next = pud_addr_end(addr, end); | |
2657 | if (pud_none(*pud) && !create) | |
2658 | continue; | |
2659 | if (WARN_ON_ONCE(pud_leaf(*pud))) | |
2660 | return -EINVAL; | |
2661 | if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { | |
2662 | if (!create) | |
2663 | continue; | |
2664 | pud_clear_bad(pud); | |
2665 | } | |
2666 | err = apply_to_pmd_range(mm, pud, addr, next, | |
2667 | fn, data, create, mask); | |
2668 | if (err) | |
2669 | break; | |
2670 | } while (pud++, addr = next, addr != end); | |
2671 | ||
2672 | return err; | |
2673 | } | |
2674 | ||
2675 | static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, | |
2676 | unsigned long addr, unsigned long end, | |
2677 | pte_fn_t fn, void *data, bool create, | |
2678 | pgtbl_mod_mask *mask) | |
2679 | { | |
2680 | p4d_t *p4d; | |
2681 | unsigned long next; | |
2682 | int err = 0; | |
2683 | ||
2684 | if (create) { | |
2685 | p4d = p4d_alloc_track(mm, pgd, addr, mask); | |
2686 | if (!p4d) | |
2687 | return -ENOMEM; | |
2688 | } else { | |
2689 | p4d = p4d_offset(pgd, addr); | |
2690 | } | |
2691 | do { | |
2692 | next = p4d_addr_end(addr, end); | |
2693 | if (p4d_none(*p4d) && !create) | |
2694 | continue; | |
2695 | if (WARN_ON_ONCE(p4d_leaf(*p4d))) | |
2696 | return -EINVAL; | |
2697 | if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { | |
2698 | if (!create) | |
2699 | continue; | |
2700 | p4d_clear_bad(p4d); | |
2701 | } | |
2702 | err = apply_to_pud_range(mm, p4d, addr, next, | |
2703 | fn, data, create, mask); | |
2704 | if (err) | |
2705 | break; | |
2706 | } while (p4d++, addr = next, addr != end); | |
2707 | ||
2708 | return err; | |
2709 | } | |
2710 | ||
2711 | static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, | |
2712 | unsigned long size, pte_fn_t fn, | |
2713 | void *data, bool create) | |
2714 | { | |
2715 | pgd_t *pgd; | |
2716 | unsigned long start = addr, next; | |
2717 | unsigned long end = addr + size; | |
2718 | pgtbl_mod_mask mask = 0; | |
2719 | int err = 0; | |
2720 | ||
2721 | if (WARN_ON(addr >= end)) | |
2722 | return -EINVAL; | |
2723 | ||
2724 | pgd = pgd_offset(mm, addr); | |
2725 | do { | |
2726 | next = pgd_addr_end(addr, end); | |
2727 | if (pgd_none(*pgd) && !create) | |
2728 | continue; | |
2729 | if (WARN_ON_ONCE(pgd_leaf(*pgd))) | |
2730 | return -EINVAL; | |
2731 | if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { | |
2732 | if (!create) | |
2733 | continue; | |
2734 | pgd_clear_bad(pgd); | |
2735 | } | |
2736 | err = apply_to_p4d_range(mm, pgd, addr, next, | |
2737 | fn, data, create, &mask); | |
2738 | if (err) | |
2739 | break; | |
2740 | } while (pgd++, addr = next, addr != end); | |
2741 | ||
2742 | if (mask & ARCH_PAGE_TABLE_SYNC_MASK) | |
2743 | arch_sync_kernel_mappings(start, start + size); | |
2744 | ||
2745 | return err; | |
2746 | } | |
2747 | ||
2748 | /* | |
2749 | * Scan a region of virtual memory, filling in page tables as necessary | |
2750 | * and calling a provided function on each leaf page table. | |
2751 | */ | |
2752 | int apply_to_page_range(struct mm_struct *mm, unsigned long addr, | |
2753 | unsigned long size, pte_fn_t fn, void *data) | |
2754 | { | |
2755 | return __apply_to_page_range(mm, addr, size, fn, data, true); | |
2756 | } | |
2757 | EXPORT_SYMBOL_GPL(apply_to_page_range); | |
2758 | ||
2759 | /* | |
2760 | * Scan a region of virtual memory, calling a provided function on | |
2761 | * each leaf page table where it exists. | |
2762 | * | |
2763 | * Unlike apply_to_page_range, this does _not_ fill in page tables | |
2764 | * where they are absent. | |
2765 | */ | |
2766 | int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr, | |
2767 | unsigned long size, pte_fn_t fn, void *data) | |
2768 | { | |
2769 | return __apply_to_page_range(mm, addr, size, fn, data, false); | |
2770 | } | |
2771 | EXPORT_SYMBOL_GPL(apply_to_existing_page_range); | |
2772 | ||
2773 | /* | |
2774 | * handle_pte_fault chooses page fault handler according to an entry which was | |
2775 | * read non-atomically. Before making any commitment, on those architectures | |
2776 | * or configurations (e.g. i386 with PAE) which might give a mix of unmatched | |
2777 | * parts, do_swap_page must check under lock before unmapping the pte and | |
2778 | * proceeding (but do_wp_page is only called after already making such a check; | |
2779 | * and do_anonymous_page can safely check later on). | |
2780 | */ | |
2781 | static inline int pte_unmap_same(struct vm_fault *vmf) | |
2782 | { | |
2783 | int same = 1; | |
2784 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION) | |
2785 | if (sizeof(pte_t) > sizeof(unsigned long)) { | |
2786 | spin_lock(vmf->ptl); | |
2787 | same = pte_same(ptep_get(vmf->pte), vmf->orig_pte); | |
2788 | spin_unlock(vmf->ptl); | |
2789 | } | |
2790 | #endif | |
2791 | pte_unmap(vmf->pte); | |
2792 | vmf->pte = NULL; | |
2793 | return same; | |
2794 | } | |
2795 | ||
2796 | /* | |
2797 | * Return: | |
2798 | * 0: copied succeeded | |
2799 | * -EHWPOISON: copy failed due to hwpoison in source page | |
2800 | * -EAGAIN: copied failed (some other reason) | |
2801 | */ | |
2802 | static inline int __wp_page_copy_user(struct page *dst, struct page *src, | |
2803 | struct vm_fault *vmf) | |
2804 | { | |
2805 | int ret; | |
2806 | void *kaddr; | |
2807 | void __user *uaddr; | |
2808 | struct vm_area_struct *vma = vmf->vma; | |
2809 | struct mm_struct *mm = vma->vm_mm; | |
2810 | unsigned long addr = vmf->address; | |
2811 | ||
2812 | if (likely(src)) { | |
2813 | if (copy_mc_user_highpage(dst, src, addr, vma)) { | |
2814 | memory_failure_queue(page_to_pfn(src), 0); | |
2815 | return -EHWPOISON; | |
2816 | } | |
2817 | return 0; | |
2818 | } | |
2819 | ||
2820 | /* | |
2821 | * If the source page was a PFN mapping, we don't have | |
2822 | * a "struct page" for it. We do a best-effort copy by | |
2823 | * just copying from the original user address. If that | |
2824 | * fails, we just zero-fill it. Live with it. | |
2825 | */ | |
2826 | kaddr = kmap_atomic(dst); | |
2827 | uaddr = (void __user *)(addr & PAGE_MASK); | |
2828 | ||
2829 | /* | |
2830 | * On architectures with software "accessed" bits, we would | |
2831 | * take a double page fault, so mark it accessed here. | |
2832 | */ | |
2833 | vmf->pte = NULL; | |
2834 | if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) { | |
2835 | pte_t entry; | |
2836 | ||
2837 | vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); | |
2838 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { | |
2839 | /* | |
2840 | * Other thread has already handled the fault | |
2841 | * and update local tlb only | |
2842 | */ | |
2843 | if (vmf->pte) | |
2844 | update_mmu_tlb(vma, addr, vmf->pte); | |
2845 | ret = -EAGAIN; | |
2846 | goto pte_unlock; | |
2847 | } | |
2848 | ||
2849 | entry = pte_mkyoung(vmf->orig_pte); | |
2850 | if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0)) | |
2851 | update_mmu_cache_range(vmf, vma, addr, vmf->pte, 1); | |
2852 | } | |
2853 | ||
2854 | /* | |
2855 | * This really shouldn't fail, because the page is there | |
2856 | * in the page tables. But it might just be unreadable, | |
2857 | * in which case we just give up and fill the result with | |
2858 | * zeroes. | |
2859 | */ | |
2860 | if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { | |
2861 | if (vmf->pte) | |
2862 | goto warn; | |
2863 | ||
2864 | /* Re-validate under PTL if the page is still mapped */ | |
2865 | vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); | |
2866 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { | |
2867 | /* The PTE changed under us, update local tlb */ | |
2868 | if (vmf->pte) | |
2869 | update_mmu_tlb(vma, addr, vmf->pte); | |
2870 | ret = -EAGAIN; | |
2871 | goto pte_unlock; | |
2872 | } | |
2873 | ||
2874 | /* | |
2875 | * The same page can be mapped back since last copy attempt. | |
2876 | * Try to copy again under PTL. | |
2877 | */ | |
2878 | if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { | |
2879 | /* | |
2880 | * Give a warn in case there can be some obscure | |
2881 | * use-case | |
2882 | */ | |
2883 | warn: | |
2884 | WARN_ON_ONCE(1); | |
2885 | clear_page(kaddr); | |
2886 | } | |
2887 | } | |
2888 | ||
2889 | ret = 0; | |
2890 | ||
2891 | pte_unlock: | |
2892 | if (vmf->pte) | |
2893 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
2894 | kunmap_atomic(kaddr); | |
2895 | flush_dcache_page(dst); | |
2896 | ||
2897 | return ret; | |
2898 | } | |
2899 | ||
2900 | static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) | |
2901 | { | |
2902 | struct file *vm_file = vma->vm_file; | |
2903 | ||
2904 | if (vm_file) | |
2905 | return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; | |
2906 | ||
2907 | /* | |
2908 | * Special mappings (e.g. VDSO) do not have any file so fake | |
2909 | * a default GFP_KERNEL for them. | |
2910 | */ | |
2911 | return GFP_KERNEL; | |
2912 | } | |
2913 | ||
2914 | /* | |
2915 | * Notify the address space that the page is about to become writable so that | |
2916 | * it can prohibit this or wait for the page to get into an appropriate state. | |
2917 | * | |
2918 | * We do this without the lock held, so that it can sleep if it needs to. | |
2919 | */ | |
2920 | static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio) | |
2921 | { | |
2922 | vm_fault_t ret; | |
2923 | unsigned int old_flags = vmf->flags; | |
2924 | ||
2925 | vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; | |
2926 | ||
2927 | if (vmf->vma->vm_file && | |
2928 | IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host)) | |
2929 | return VM_FAULT_SIGBUS; | |
2930 | ||
2931 | ret = vmf->vma->vm_ops->page_mkwrite(vmf); | |
2932 | /* Restore original flags so that caller is not surprised */ | |
2933 | vmf->flags = old_flags; | |
2934 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) | |
2935 | return ret; | |
2936 | if (unlikely(!(ret & VM_FAULT_LOCKED))) { | |
2937 | folio_lock(folio); | |
2938 | if (!folio->mapping) { | |
2939 | folio_unlock(folio); | |
2940 | return 0; /* retry */ | |
2941 | } | |
2942 | ret |= VM_FAULT_LOCKED; | |
2943 | } else | |
2944 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); | |
2945 | return ret; | |
2946 | } | |
2947 | ||
2948 | /* | |
2949 | * Handle dirtying of a page in shared file mapping on a write fault. | |
2950 | * | |
2951 | * The function expects the page to be locked and unlocks it. | |
2952 | */ | |
2953 | static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf) | |
2954 | { | |
2955 | struct vm_area_struct *vma = vmf->vma; | |
2956 | struct address_space *mapping; | |
2957 | struct folio *folio = page_folio(vmf->page); | |
2958 | bool dirtied; | |
2959 | bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; | |
2960 | ||
2961 | dirtied = folio_mark_dirty(folio); | |
2962 | VM_BUG_ON_FOLIO(folio_test_anon(folio), folio); | |
2963 | /* | |
2964 | * Take a local copy of the address_space - folio.mapping may be zeroed | |
2965 | * by truncate after folio_unlock(). The address_space itself remains | |
2966 | * pinned by vma->vm_file's reference. We rely on folio_unlock()'s | |
2967 | * release semantics to prevent the compiler from undoing this copying. | |
2968 | */ | |
2969 | mapping = folio_raw_mapping(folio); | |
2970 | folio_unlock(folio); | |
2971 | ||
2972 | if (!page_mkwrite) | |
2973 | file_update_time(vma->vm_file); | |
2974 | ||
2975 | /* | |
2976 | * Throttle page dirtying rate down to writeback speed. | |
2977 | * | |
2978 | * mapping may be NULL here because some device drivers do not | |
2979 | * set page.mapping but still dirty their pages | |
2980 | * | |
2981 | * Drop the mmap_lock before waiting on IO, if we can. The file | |
2982 | * is pinning the mapping, as per above. | |
2983 | */ | |
2984 | if ((dirtied || page_mkwrite) && mapping) { | |
2985 | struct file *fpin; | |
2986 | ||
2987 | fpin = maybe_unlock_mmap_for_io(vmf, NULL); | |
2988 | balance_dirty_pages_ratelimited(mapping); | |
2989 | if (fpin) { | |
2990 | fput(fpin); | |
2991 | return VM_FAULT_COMPLETED; | |
2992 | } | |
2993 | } | |
2994 | ||
2995 | return 0; | |
2996 | } | |
2997 | ||
2998 | /* | |
2999 | * Handle write page faults for pages that can be reused in the current vma | |
3000 | * | |
3001 | * This can happen either due to the mapping being with the VM_SHARED flag, | |
3002 | * or due to us being the last reference standing to the page. In either | |
3003 | * case, all we need to do here is to mark the page as writable and update | |
3004 | * any related book-keeping. | |
3005 | */ | |
3006 | static inline void wp_page_reuse(struct vm_fault *vmf) | |
3007 | __releases(vmf->ptl) | |
3008 | { | |
3009 | struct vm_area_struct *vma = vmf->vma; | |
3010 | struct page *page = vmf->page; | |
3011 | pte_t entry; | |
3012 | ||
3013 | VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE)); | |
3014 | VM_BUG_ON(page && PageAnon(page) && !PageAnonExclusive(page)); | |
3015 | ||
3016 | /* | |
3017 | * Clear the pages cpupid information as the existing | |
3018 | * information potentially belongs to a now completely | |
3019 | * unrelated process. | |
3020 | */ | |
3021 | if (page) | |
3022 | page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); | |
3023 | ||
3024 | flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); | |
3025 | entry = pte_mkyoung(vmf->orig_pte); | |
3026 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
3027 | if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) | |
3028 | update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1); | |
3029 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3030 | count_vm_event(PGREUSE); | |
3031 | } | |
3032 | ||
3033 | /* | |
3034 | * Handle the case of a page which we actually need to copy to a new page, | |
3035 | * either due to COW or unsharing. | |
3036 | * | |
3037 | * Called with mmap_lock locked and the old page referenced, but | |
3038 | * without the ptl held. | |
3039 | * | |
3040 | * High level logic flow: | |
3041 | * | |
3042 | * - Allocate a page, copy the content of the old page to the new one. | |
3043 | * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. | |
3044 | * - Take the PTL. If the pte changed, bail out and release the allocated page | |
3045 | * - If the pte is still the way we remember it, update the page table and all | |
3046 | * relevant references. This includes dropping the reference the page-table | |
3047 | * held to the old page, as well as updating the rmap. | |
3048 | * - In any case, unlock the PTL and drop the reference we took to the old page. | |
3049 | */ | |
3050 | static vm_fault_t wp_page_copy(struct vm_fault *vmf) | |
3051 | { | |
3052 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; | |
3053 | struct vm_area_struct *vma = vmf->vma; | |
3054 | struct mm_struct *mm = vma->vm_mm; | |
3055 | struct folio *old_folio = NULL; | |
3056 | struct folio *new_folio = NULL; | |
3057 | pte_t entry; | |
3058 | int page_copied = 0; | |
3059 | struct mmu_notifier_range range; | |
3060 | int ret; | |
3061 | ||
3062 | delayacct_wpcopy_start(); | |
3063 | ||
3064 | if (vmf->page) | |
3065 | old_folio = page_folio(vmf->page); | |
3066 | if (unlikely(anon_vma_prepare(vma))) | |
3067 | goto oom; | |
3068 | ||
3069 | if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { | |
3070 | new_folio = vma_alloc_zeroed_movable_folio(vma, vmf->address); | |
3071 | if (!new_folio) | |
3072 | goto oom; | |
3073 | } else { | |
3074 | new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, | |
3075 | vmf->address, false); | |
3076 | if (!new_folio) | |
3077 | goto oom; | |
3078 | ||
3079 | ret = __wp_page_copy_user(&new_folio->page, vmf->page, vmf); | |
3080 | if (ret) { | |
3081 | /* | |
3082 | * COW failed, if the fault was solved by other, | |
3083 | * it's fine. If not, userspace would re-fault on | |
3084 | * the same address and we will handle the fault | |
3085 | * from the second attempt. | |
3086 | * The -EHWPOISON case will not be retried. | |
3087 | */ | |
3088 | folio_put(new_folio); | |
3089 | if (old_folio) | |
3090 | folio_put(old_folio); | |
3091 | ||
3092 | delayacct_wpcopy_end(); | |
3093 | return ret == -EHWPOISON ? VM_FAULT_HWPOISON : 0; | |
3094 | } | |
3095 | kmsan_copy_page_meta(&new_folio->page, vmf->page); | |
3096 | } | |
3097 | ||
3098 | if (mem_cgroup_charge(new_folio, mm, GFP_KERNEL)) | |
3099 | goto oom_free_new; | |
3100 | folio_throttle_swaprate(new_folio, GFP_KERNEL); | |
3101 | ||
3102 | __folio_mark_uptodate(new_folio); | |
3103 | ||
3104 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, | |
3105 | vmf->address & PAGE_MASK, | |
3106 | (vmf->address & PAGE_MASK) + PAGE_SIZE); | |
3107 | mmu_notifier_invalidate_range_start(&range); | |
3108 | ||
3109 | /* | |
3110 | * Re-check the pte - we dropped the lock | |
3111 | */ | |
3112 | vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); | |
3113 | if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { | |
3114 | if (old_folio) { | |
3115 | if (!folio_test_anon(old_folio)) { | |
3116 | dec_mm_counter(mm, mm_counter_file(&old_folio->page)); | |
3117 | inc_mm_counter(mm, MM_ANONPAGES); | |
3118 | } | |
3119 | } else { | |
3120 | ksm_might_unmap_zero_page(mm, vmf->orig_pte); | |
3121 | inc_mm_counter(mm, MM_ANONPAGES); | |
3122 | } | |
3123 | flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); | |
3124 | entry = mk_pte(&new_folio->page, vma->vm_page_prot); | |
3125 | entry = pte_sw_mkyoung(entry); | |
3126 | if (unlikely(unshare)) { | |
3127 | if (pte_soft_dirty(vmf->orig_pte)) | |
3128 | entry = pte_mksoft_dirty(entry); | |
3129 | if (pte_uffd_wp(vmf->orig_pte)) | |
3130 | entry = pte_mkuffd_wp(entry); | |
3131 | } else { | |
3132 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
3133 | } | |
3134 | ||
3135 | /* | |
3136 | * Clear the pte entry and flush it first, before updating the | |
3137 | * pte with the new entry, to keep TLBs on different CPUs in | |
3138 | * sync. This code used to set the new PTE then flush TLBs, but | |
3139 | * that left a window where the new PTE could be loaded into | |
3140 | * some TLBs while the old PTE remains in others. | |
3141 | */ | |
3142 | ptep_clear_flush(vma, vmf->address, vmf->pte); | |
3143 | folio_add_new_anon_rmap(new_folio, vma, vmf->address); | |
3144 | folio_add_lru_vma(new_folio, vma); | |
3145 | /* | |
3146 | * We call the notify macro here because, when using secondary | |
3147 | * mmu page tables (such as kvm shadow page tables), we want the | |
3148 | * new page to be mapped directly into the secondary page table. | |
3149 | */ | |
3150 | BUG_ON(unshare && pte_write(entry)); | |
3151 | set_pte_at_notify(mm, vmf->address, vmf->pte, entry); | |
3152 | update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1); | |
3153 | if (old_folio) { | |
3154 | /* | |
3155 | * Only after switching the pte to the new page may | |
3156 | * we remove the mapcount here. Otherwise another | |
3157 | * process may come and find the rmap count decremented | |
3158 | * before the pte is switched to the new page, and | |
3159 | * "reuse" the old page writing into it while our pte | |
3160 | * here still points into it and can be read by other | |
3161 | * threads. | |
3162 | * | |
3163 | * The critical issue is to order this | |
3164 | * page_remove_rmap with the ptp_clear_flush above. | |
3165 | * Those stores are ordered by (if nothing else,) | |
3166 | * the barrier present in the atomic_add_negative | |
3167 | * in page_remove_rmap. | |
3168 | * | |
3169 | * Then the TLB flush in ptep_clear_flush ensures that | |
3170 | * no process can access the old page before the | |
3171 | * decremented mapcount is visible. And the old page | |
3172 | * cannot be reused until after the decremented | |
3173 | * mapcount is visible. So transitively, TLBs to | |
3174 | * old page will be flushed before it can be reused. | |
3175 | */ | |
3176 | page_remove_rmap(vmf->page, vma, false); | |
3177 | } | |
3178 | ||
3179 | /* Free the old page.. */ | |
3180 | new_folio = old_folio; | |
3181 | page_copied = 1; | |
3182 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3183 | } else if (vmf->pte) { | |
3184 | update_mmu_tlb(vma, vmf->address, vmf->pte); | |
3185 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3186 | } | |
3187 | ||
3188 | mmu_notifier_invalidate_range_end(&range); | |
3189 | ||
3190 | if (new_folio) | |
3191 | folio_put(new_folio); | |
3192 | if (old_folio) { | |
3193 | if (page_copied) | |
3194 | free_swap_cache(&old_folio->page); | |
3195 | folio_put(old_folio); | |
3196 | } | |
3197 | ||
3198 | delayacct_wpcopy_end(); | |
3199 | return 0; | |
3200 | oom_free_new: | |
3201 | folio_put(new_folio); | |
3202 | oom: | |
3203 | if (old_folio) | |
3204 | folio_put(old_folio); | |
3205 | ||
3206 | delayacct_wpcopy_end(); | |
3207 | return VM_FAULT_OOM; | |
3208 | } | |
3209 | ||
3210 | /** | |
3211 | * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE | |
3212 | * writeable once the page is prepared | |
3213 | * | |
3214 | * @vmf: structure describing the fault | |
3215 | * | |
3216 | * This function handles all that is needed to finish a write page fault in a | |
3217 | * shared mapping due to PTE being read-only once the mapped page is prepared. | |
3218 | * It handles locking of PTE and modifying it. | |
3219 | * | |
3220 | * The function expects the page to be locked or other protection against | |
3221 | * concurrent faults / writeback (such as DAX radix tree locks). | |
3222 | * | |
3223 | * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before | |
3224 | * we acquired PTE lock. | |
3225 | */ | |
3226 | vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf) | |
3227 | { | |
3228 | WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); | |
3229 | vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, | |
3230 | &vmf->ptl); | |
3231 | if (!vmf->pte) | |
3232 | return VM_FAULT_NOPAGE; | |
3233 | /* | |
3234 | * We might have raced with another page fault while we released the | |
3235 | * pte_offset_map_lock. | |
3236 | */ | |
3237 | if (!pte_same(ptep_get(vmf->pte), vmf->orig_pte)) { | |
3238 | update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); | |
3239 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3240 | return VM_FAULT_NOPAGE; | |
3241 | } | |
3242 | wp_page_reuse(vmf); | |
3243 | return 0; | |
3244 | } | |
3245 | ||
3246 | /* | |
3247 | * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED | |
3248 | * mapping | |
3249 | */ | |
3250 | static vm_fault_t wp_pfn_shared(struct vm_fault *vmf) | |
3251 | { | |
3252 | struct vm_area_struct *vma = vmf->vma; | |
3253 | ||
3254 | if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { | |
3255 | vm_fault_t ret; | |
3256 | ||
3257 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3258 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
3259 | vma_end_read(vmf->vma); | |
3260 | return VM_FAULT_RETRY; | |
3261 | } | |
3262 | ||
3263 | vmf->flags |= FAULT_FLAG_MKWRITE; | |
3264 | ret = vma->vm_ops->pfn_mkwrite(vmf); | |
3265 | if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) | |
3266 | return ret; | |
3267 | return finish_mkwrite_fault(vmf); | |
3268 | } | |
3269 | wp_page_reuse(vmf); | |
3270 | return 0; | |
3271 | } | |
3272 | ||
3273 | static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio) | |
3274 | __releases(vmf->ptl) | |
3275 | { | |
3276 | struct vm_area_struct *vma = vmf->vma; | |
3277 | vm_fault_t ret = 0; | |
3278 | ||
3279 | folio_get(folio); | |
3280 | ||
3281 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) { | |
3282 | vm_fault_t tmp; | |
3283 | ||
3284 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3285 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
3286 | folio_put(folio); | |
3287 | vma_end_read(vmf->vma); | |
3288 | return VM_FAULT_RETRY; | |
3289 | } | |
3290 | ||
3291 | tmp = do_page_mkwrite(vmf, folio); | |
3292 | if (unlikely(!tmp || (tmp & | |
3293 | (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { | |
3294 | folio_put(folio); | |
3295 | return tmp; | |
3296 | } | |
3297 | tmp = finish_mkwrite_fault(vmf); | |
3298 | if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { | |
3299 | folio_unlock(folio); | |
3300 | folio_put(folio); | |
3301 | return tmp; | |
3302 | } | |
3303 | } else { | |
3304 | wp_page_reuse(vmf); | |
3305 | folio_lock(folio); | |
3306 | } | |
3307 | ret |= fault_dirty_shared_page(vmf); | |
3308 | folio_put(folio); | |
3309 | ||
3310 | return ret; | |
3311 | } | |
3312 | ||
3313 | /* | |
3314 | * This routine handles present pages, when | |
3315 | * * users try to write to a shared page (FAULT_FLAG_WRITE) | |
3316 | * * GUP wants to take a R/O pin on a possibly shared anonymous page | |
3317 | * (FAULT_FLAG_UNSHARE) | |
3318 | * | |
3319 | * It is done by copying the page to a new address and decrementing the | |
3320 | * shared-page counter for the old page. | |
3321 | * | |
3322 | * Note that this routine assumes that the protection checks have been | |
3323 | * done by the caller (the low-level page fault routine in most cases). | |
3324 | * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've | |
3325 | * done any necessary COW. | |
3326 | * | |
3327 | * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even | |
3328 | * though the page will change only once the write actually happens. This | |
3329 | * avoids a few races, and potentially makes it more efficient. | |
3330 | * | |
3331 | * We enter with non-exclusive mmap_lock (to exclude vma changes, | |
3332 | * but allow concurrent faults), with pte both mapped and locked. | |
3333 | * We return with mmap_lock still held, but pte unmapped and unlocked. | |
3334 | */ | |
3335 | static vm_fault_t do_wp_page(struct vm_fault *vmf) | |
3336 | __releases(vmf->ptl) | |
3337 | { | |
3338 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; | |
3339 | struct vm_area_struct *vma = vmf->vma; | |
3340 | struct folio *folio = NULL; | |
3341 | ||
3342 | if (likely(!unshare)) { | |
3343 | if (userfaultfd_pte_wp(vma, ptep_get(vmf->pte))) { | |
3344 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3345 | return handle_userfault(vmf, VM_UFFD_WP); | |
3346 | } | |
3347 | ||
3348 | /* | |
3349 | * Userfaultfd write-protect can defer flushes. Ensure the TLB | |
3350 | * is flushed in this case before copying. | |
3351 | */ | |
3352 | if (unlikely(userfaultfd_wp(vmf->vma) && | |
3353 | mm_tlb_flush_pending(vmf->vma->vm_mm))) | |
3354 | flush_tlb_page(vmf->vma, vmf->address); | |
3355 | } | |
3356 | ||
3357 | vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); | |
3358 | ||
3359 | if (vmf->page) | |
3360 | folio = page_folio(vmf->page); | |
3361 | ||
3362 | /* | |
3363 | * Shared mapping: we are guaranteed to have VM_WRITE and | |
3364 | * FAULT_FLAG_WRITE set at this point. | |
3365 | */ | |
3366 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { | |
3367 | /* | |
3368 | * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a | |
3369 | * VM_PFNMAP VMA. | |
3370 | * | |
3371 | * We should not cow pages in a shared writeable mapping. | |
3372 | * Just mark the pages writable and/or call ops->pfn_mkwrite. | |
3373 | */ | |
3374 | if (!vmf->page) | |
3375 | return wp_pfn_shared(vmf); | |
3376 | return wp_page_shared(vmf, folio); | |
3377 | } | |
3378 | ||
3379 | /* | |
3380 | * Private mapping: create an exclusive anonymous page copy if reuse | |
3381 | * is impossible. We might miss VM_WRITE for FOLL_FORCE handling. | |
3382 | */ | |
3383 | if (folio && folio_test_anon(folio)) { | |
3384 | /* | |
3385 | * If the page is exclusive to this process we must reuse the | |
3386 | * page without further checks. | |
3387 | */ | |
3388 | if (PageAnonExclusive(vmf->page)) | |
3389 | goto reuse; | |
3390 | ||
3391 | /* | |
3392 | * We have to verify under folio lock: these early checks are | |
3393 | * just an optimization to avoid locking the folio and freeing | |
3394 | * the swapcache if there is little hope that we can reuse. | |
3395 | * | |
3396 | * KSM doesn't necessarily raise the folio refcount. | |
3397 | */ | |
3398 | if (folio_test_ksm(folio) || folio_ref_count(folio) > 3) | |
3399 | goto copy; | |
3400 | if (!folio_test_lru(folio)) | |
3401 | /* | |
3402 | * We cannot easily detect+handle references from | |
3403 | * remote LRU caches or references to LRU folios. | |
3404 | */ | |
3405 | lru_add_drain(); | |
3406 | if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio)) | |
3407 | goto copy; | |
3408 | if (!folio_trylock(folio)) | |
3409 | goto copy; | |
3410 | if (folio_test_swapcache(folio)) | |
3411 | folio_free_swap(folio); | |
3412 | if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) { | |
3413 | folio_unlock(folio); | |
3414 | goto copy; | |
3415 | } | |
3416 | /* | |
3417 | * Ok, we've got the only folio reference from our mapping | |
3418 | * and the folio is locked, it's dark out, and we're wearing | |
3419 | * sunglasses. Hit it. | |
3420 | */ | |
3421 | page_move_anon_rmap(vmf->page, vma); | |
3422 | folio_unlock(folio); | |
3423 | reuse: | |
3424 | if (unlikely(unshare)) { | |
3425 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3426 | return 0; | |
3427 | } | |
3428 | wp_page_reuse(vmf); | |
3429 | return 0; | |
3430 | } | |
3431 | copy: | |
3432 | if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma->anon_vma) { | |
3433 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3434 | vma_end_read(vmf->vma); | |
3435 | return VM_FAULT_RETRY; | |
3436 | } | |
3437 | ||
3438 | /* | |
3439 | * Ok, we need to copy. Oh, well.. | |
3440 | */ | |
3441 | if (folio) | |
3442 | folio_get(folio); | |
3443 | ||
3444 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3445 | #ifdef CONFIG_KSM | |
3446 | if (folio && folio_test_ksm(folio)) | |
3447 | count_vm_event(COW_KSM); | |
3448 | #endif | |
3449 | return wp_page_copy(vmf); | |
3450 | } | |
3451 | ||
3452 | static void unmap_mapping_range_vma(struct vm_area_struct *vma, | |
3453 | unsigned long start_addr, unsigned long end_addr, | |
3454 | struct zap_details *details) | |
3455 | { | |
3456 | zap_page_range_single(vma, start_addr, end_addr - start_addr, details); | |
3457 | } | |
3458 | ||
3459 | static inline void unmap_mapping_range_tree(struct rb_root_cached *root, | |
3460 | pgoff_t first_index, | |
3461 | pgoff_t last_index, | |
3462 | struct zap_details *details) | |
3463 | { | |
3464 | struct vm_area_struct *vma; | |
3465 | pgoff_t vba, vea, zba, zea; | |
3466 | ||
3467 | vma_interval_tree_foreach(vma, root, first_index, last_index) { | |
3468 | vba = vma->vm_pgoff; | |
3469 | vea = vba + vma_pages(vma) - 1; | |
3470 | zba = max(first_index, vba); | |
3471 | zea = min(last_index, vea); | |
3472 | ||
3473 | unmap_mapping_range_vma(vma, | |
3474 | ((zba - vba) << PAGE_SHIFT) + vma->vm_start, | |
3475 | ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, | |
3476 | details); | |
3477 | } | |
3478 | } | |
3479 | ||
3480 | /** | |
3481 | * unmap_mapping_folio() - Unmap single folio from processes. | |
3482 | * @folio: The locked folio to be unmapped. | |
3483 | * | |
3484 | * Unmap this folio from any userspace process which still has it mmaped. | |
3485 | * Typically, for efficiency, the range of nearby pages has already been | |
3486 | * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once | |
3487 | * truncation or invalidation holds the lock on a folio, it may find that | |
3488 | * the page has been remapped again: and then uses unmap_mapping_folio() | |
3489 | * to unmap it finally. | |
3490 | */ | |
3491 | void unmap_mapping_folio(struct folio *folio) | |
3492 | { | |
3493 | struct address_space *mapping = folio->mapping; | |
3494 | struct zap_details details = { }; | |
3495 | pgoff_t first_index; | |
3496 | pgoff_t last_index; | |
3497 | ||
3498 | VM_BUG_ON(!folio_test_locked(folio)); | |
3499 | ||
3500 | first_index = folio->index; | |
3501 | last_index = folio_next_index(folio) - 1; | |
3502 | ||
3503 | details.even_cows = false; | |
3504 | details.single_folio = folio; | |
3505 | details.zap_flags = ZAP_FLAG_DROP_MARKER; | |
3506 | ||
3507 | i_mmap_lock_read(mapping); | |
3508 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) | |
3509 | unmap_mapping_range_tree(&mapping->i_mmap, first_index, | |
3510 | last_index, &details); | |
3511 | i_mmap_unlock_read(mapping); | |
3512 | } | |
3513 | ||
3514 | /** | |
3515 | * unmap_mapping_pages() - Unmap pages from processes. | |
3516 | * @mapping: The address space containing pages to be unmapped. | |
3517 | * @start: Index of first page to be unmapped. | |
3518 | * @nr: Number of pages to be unmapped. 0 to unmap to end of file. | |
3519 | * @even_cows: Whether to unmap even private COWed pages. | |
3520 | * | |
3521 | * Unmap the pages in this address space from any userspace process which | |
3522 | * has them mmaped. Generally, you want to remove COWed pages as well when | |
3523 | * a file is being truncated, but not when invalidating pages from the page | |
3524 | * cache. | |
3525 | */ | |
3526 | void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, | |
3527 | pgoff_t nr, bool even_cows) | |
3528 | { | |
3529 | struct zap_details details = { }; | |
3530 | pgoff_t first_index = start; | |
3531 | pgoff_t last_index = start + nr - 1; | |
3532 | ||
3533 | details.even_cows = even_cows; | |
3534 | if (last_index < first_index) | |
3535 | last_index = ULONG_MAX; | |
3536 | ||
3537 | i_mmap_lock_read(mapping); | |
3538 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) | |
3539 | unmap_mapping_range_tree(&mapping->i_mmap, first_index, | |
3540 | last_index, &details); | |
3541 | i_mmap_unlock_read(mapping); | |
3542 | } | |
3543 | EXPORT_SYMBOL_GPL(unmap_mapping_pages); | |
3544 | ||
3545 | /** | |
3546 | * unmap_mapping_range - unmap the portion of all mmaps in the specified | |
3547 | * address_space corresponding to the specified byte range in the underlying | |
3548 | * file. | |
3549 | * | |
3550 | * @mapping: the address space containing mmaps to be unmapped. | |
3551 | * @holebegin: byte in first page to unmap, relative to the start of | |
3552 | * the underlying file. This will be rounded down to a PAGE_SIZE | |
3553 | * boundary. Note that this is different from truncate_pagecache(), which | |
3554 | * must keep the partial page. In contrast, we must get rid of | |
3555 | * partial pages. | |
3556 | * @holelen: size of prospective hole in bytes. This will be rounded | |
3557 | * up to a PAGE_SIZE boundary. A holelen of zero truncates to the | |
3558 | * end of the file. | |
3559 | * @even_cows: 1 when truncating a file, unmap even private COWed pages; | |
3560 | * but 0 when invalidating pagecache, don't throw away private data. | |
3561 | */ | |
3562 | void unmap_mapping_range(struct address_space *mapping, | |
3563 | loff_t const holebegin, loff_t const holelen, int even_cows) | |
3564 | { | |
3565 | pgoff_t hba = holebegin >> PAGE_SHIFT; | |
3566 | pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
3567 | ||
3568 | /* Check for overflow. */ | |
3569 | if (sizeof(holelen) > sizeof(hlen)) { | |
3570 | long long holeend = | |
3571 | (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
3572 | if (holeend & ~(long long)ULONG_MAX) | |
3573 | hlen = ULONG_MAX - hba + 1; | |
3574 | } | |
3575 | ||
3576 | unmap_mapping_pages(mapping, hba, hlen, even_cows); | |
3577 | } | |
3578 | EXPORT_SYMBOL(unmap_mapping_range); | |
3579 | ||
3580 | /* | |
3581 | * Restore a potential device exclusive pte to a working pte entry | |
3582 | */ | |
3583 | static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) | |
3584 | { | |
3585 | struct folio *folio = page_folio(vmf->page); | |
3586 | struct vm_area_struct *vma = vmf->vma; | |
3587 | struct mmu_notifier_range range; | |
3588 | vm_fault_t ret; | |
3589 | ||
3590 | /* | |
3591 | * We need a reference to lock the folio because we don't hold | |
3592 | * the PTL so a racing thread can remove the device-exclusive | |
3593 | * entry and unmap it. If the folio is free the entry must | |
3594 | * have been removed already. If it happens to have already | |
3595 | * been re-allocated after being freed all we do is lock and | |
3596 | * unlock it. | |
3597 | */ | |
3598 | if (!folio_try_get(folio)) | |
3599 | return 0; | |
3600 | ||
3601 | ret = folio_lock_or_retry(folio, vmf); | |
3602 | if (ret) { | |
3603 | folio_put(folio); | |
3604 | return ret; | |
3605 | } | |
3606 | mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, | |
3607 | vma->vm_mm, vmf->address & PAGE_MASK, | |
3608 | (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL); | |
3609 | mmu_notifier_invalidate_range_start(&range); | |
3610 | ||
3611 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, | |
3612 | &vmf->ptl); | |
3613 | if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) | |
3614 | restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte); | |
3615 | ||
3616 | if (vmf->pte) | |
3617 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3618 | folio_unlock(folio); | |
3619 | folio_put(folio); | |
3620 | ||
3621 | mmu_notifier_invalidate_range_end(&range); | |
3622 | return 0; | |
3623 | } | |
3624 | ||
3625 | static inline bool should_try_to_free_swap(struct folio *folio, | |
3626 | struct vm_area_struct *vma, | |
3627 | unsigned int fault_flags) | |
3628 | { | |
3629 | if (!folio_test_swapcache(folio)) | |
3630 | return false; | |
3631 | if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) || | |
3632 | folio_test_mlocked(folio)) | |
3633 | return true; | |
3634 | /* | |
3635 | * If we want to map a page that's in the swapcache writable, we | |
3636 | * have to detect via the refcount if we're really the exclusive | |
3637 | * user. Try freeing the swapcache to get rid of the swapcache | |
3638 | * reference only in case it's likely that we'll be the exlusive user. | |
3639 | */ | |
3640 | return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) && | |
3641 | folio_ref_count(folio) == 2; | |
3642 | } | |
3643 | ||
3644 | static vm_fault_t pte_marker_clear(struct vm_fault *vmf) | |
3645 | { | |
3646 | vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, | |
3647 | vmf->address, &vmf->ptl); | |
3648 | if (!vmf->pte) | |
3649 | return 0; | |
3650 | /* | |
3651 | * Be careful so that we will only recover a special uffd-wp pte into a | |
3652 | * none pte. Otherwise it means the pte could have changed, so retry. | |
3653 | * | |
3654 | * This should also cover the case where e.g. the pte changed | |
3655 | * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_POISONED. | |
3656 | * So is_pte_marker() check is not enough to safely drop the pte. | |
3657 | */ | |
3658 | if (pte_same(vmf->orig_pte, ptep_get(vmf->pte))) | |
3659 | pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte); | |
3660 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3661 | return 0; | |
3662 | } | |
3663 | ||
3664 | static vm_fault_t do_pte_missing(struct vm_fault *vmf) | |
3665 | { | |
3666 | if (vma_is_anonymous(vmf->vma)) | |
3667 | return do_anonymous_page(vmf); | |
3668 | else | |
3669 | return do_fault(vmf); | |
3670 | } | |
3671 | ||
3672 | /* | |
3673 | * This is actually a page-missing access, but with uffd-wp special pte | |
3674 | * installed. It means this pte was wr-protected before being unmapped. | |
3675 | */ | |
3676 | static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf) | |
3677 | { | |
3678 | /* | |
3679 | * Just in case there're leftover special ptes even after the region | |
3680 | * got unregistered - we can simply clear them. | |
3681 | */ | |
3682 | if (unlikely(!userfaultfd_wp(vmf->vma))) | |
3683 | return pte_marker_clear(vmf); | |
3684 | ||
3685 | return do_pte_missing(vmf); | |
3686 | } | |
3687 | ||
3688 | static vm_fault_t handle_pte_marker(struct vm_fault *vmf) | |
3689 | { | |
3690 | swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte); | |
3691 | unsigned long marker = pte_marker_get(entry); | |
3692 | ||
3693 | /* | |
3694 | * PTE markers should never be empty. If anything weird happened, | |
3695 | * the best thing to do is to kill the process along with its mm. | |
3696 | */ | |
3697 | if (WARN_ON_ONCE(!marker)) | |
3698 | return VM_FAULT_SIGBUS; | |
3699 | ||
3700 | /* Higher priority than uffd-wp when data corrupted */ | |
3701 | if (marker & PTE_MARKER_POISONED) | |
3702 | return VM_FAULT_HWPOISON; | |
3703 | ||
3704 | if (pte_marker_entry_uffd_wp(entry)) | |
3705 | return pte_marker_handle_uffd_wp(vmf); | |
3706 | ||
3707 | /* This is an unknown pte marker */ | |
3708 | return VM_FAULT_SIGBUS; | |
3709 | } | |
3710 | ||
3711 | /* | |
3712 | * We enter with non-exclusive mmap_lock (to exclude vma changes, | |
3713 | * but allow concurrent faults), and pte mapped but not yet locked. | |
3714 | * We return with pte unmapped and unlocked. | |
3715 | * | |
3716 | * We return with the mmap_lock locked or unlocked in the same cases | |
3717 | * as does filemap_fault(). | |
3718 | */ | |
3719 | vm_fault_t do_swap_page(struct vm_fault *vmf) | |
3720 | { | |
3721 | struct vm_area_struct *vma = vmf->vma; | |
3722 | struct folio *swapcache, *folio = NULL; | |
3723 | struct page *page; | |
3724 | struct swap_info_struct *si = NULL; | |
3725 | rmap_t rmap_flags = RMAP_NONE; | |
3726 | bool exclusive = false; | |
3727 | swp_entry_t entry; | |
3728 | pte_t pte; | |
3729 | vm_fault_t ret = 0; | |
3730 | void *shadow = NULL; | |
3731 | ||
3732 | if (!pte_unmap_same(vmf)) | |
3733 | goto out; | |
3734 | ||
3735 | entry = pte_to_swp_entry(vmf->orig_pte); | |
3736 | if (unlikely(non_swap_entry(entry))) { | |
3737 | if (is_migration_entry(entry)) { | |
3738 | migration_entry_wait(vma->vm_mm, vmf->pmd, | |
3739 | vmf->address); | |
3740 | } else if (is_device_exclusive_entry(entry)) { | |
3741 | vmf->page = pfn_swap_entry_to_page(entry); | |
3742 | ret = remove_device_exclusive_entry(vmf); | |
3743 | } else if (is_device_private_entry(entry)) { | |
3744 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
3745 | /* | |
3746 | * migrate_to_ram is not yet ready to operate | |
3747 | * under VMA lock. | |
3748 | */ | |
3749 | vma_end_read(vma); | |
3750 | ret = VM_FAULT_RETRY; | |
3751 | goto out; | |
3752 | } | |
3753 | ||
3754 | vmf->page = pfn_swap_entry_to_page(entry); | |
3755 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, | |
3756 | vmf->address, &vmf->ptl); | |
3757 | if (unlikely(!vmf->pte || | |
3758 | !pte_same(ptep_get(vmf->pte), | |
3759 | vmf->orig_pte))) | |
3760 | goto unlock; | |
3761 | ||
3762 | /* | |
3763 | * Get a page reference while we know the page can't be | |
3764 | * freed. | |
3765 | */ | |
3766 | get_page(vmf->page); | |
3767 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
3768 | ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); | |
3769 | put_page(vmf->page); | |
3770 | } else if (is_hwpoison_entry(entry)) { | |
3771 | ret = VM_FAULT_HWPOISON; | |
3772 | } else if (is_pte_marker_entry(entry)) { | |
3773 | ret = handle_pte_marker(vmf); | |
3774 | } else { | |
3775 | print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); | |
3776 | ret = VM_FAULT_SIGBUS; | |
3777 | } | |
3778 | goto out; | |
3779 | } | |
3780 | ||
3781 | /* Prevent swapoff from happening to us. */ | |
3782 | si = get_swap_device(entry); | |
3783 | if (unlikely(!si)) | |
3784 | goto out; | |
3785 | ||
3786 | folio = swap_cache_get_folio(entry, vma, vmf->address); | |
3787 | if (folio) | |
3788 | page = folio_file_page(folio, swp_offset(entry)); | |
3789 | swapcache = folio; | |
3790 | ||
3791 | if (!folio) { | |
3792 | if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && | |
3793 | __swap_count(entry) == 1) { | |
3794 | /* skip swapcache */ | |
3795 | folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, | |
3796 | vma, vmf->address, false); | |
3797 | page = &folio->page; | |
3798 | if (folio) { | |
3799 | __folio_set_locked(folio); | |
3800 | __folio_set_swapbacked(folio); | |
3801 | ||
3802 | if (mem_cgroup_swapin_charge_folio(folio, | |
3803 | vma->vm_mm, GFP_KERNEL, | |
3804 | entry)) { | |
3805 | ret = VM_FAULT_OOM; | |
3806 | goto out_page; | |
3807 | } | |
3808 | mem_cgroup_swapin_uncharge_swap(entry); | |
3809 | ||
3810 | shadow = get_shadow_from_swap_cache(entry); | |
3811 | if (shadow) | |
3812 | workingset_refault(folio, shadow); | |
3813 | ||
3814 | folio_add_lru(folio); | |
3815 | ||
3816 | /* To provide entry to swap_readpage() */ | |
3817 | folio->swap = entry; | |
3818 | swap_readpage(page, true, NULL); | |
3819 | folio->private = NULL; | |
3820 | } | |
3821 | } else { | |
3822 | page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, | |
3823 | vmf); | |
3824 | if (page) | |
3825 | folio = page_folio(page); | |
3826 | swapcache = folio; | |
3827 | } | |
3828 | ||
3829 | if (!folio) { | |
3830 | /* | |
3831 | * Back out if somebody else faulted in this pte | |
3832 | * while we released the pte lock. | |
3833 | */ | |
3834 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, | |
3835 | vmf->address, &vmf->ptl); | |
3836 | if (likely(vmf->pte && | |
3837 | pte_same(ptep_get(vmf->pte), vmf->orig_pte))) | |
3838 | ret = VM_FAULT_OOM; | |
3839 | goto unlock; | |
3840 | } | |
3841 | ||
3842 | /* Had to read the page from swap area: Major fault */ | |
3843 | ret = VM_FAULT_MAJOR; | |
3844 | count_vm_event(PGMAJFAULT); | |
3845 | count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); | |
3846 | } else if (PageHWPoison(page)) { | |
3847 | /* | |
3848 | * hwpoisoned dirty swapcache pages are kept for killing | |
3849 | * owner processes (which may be unknown at hwpoison time) | |
3850 | */ | |
3851 | ret = VM_FAULT_HWPOISON; | |
3852 | goto out_release; | |
3853 | } | |
3854 | ||
3855 | ret |= folio_lock_or_retry(folio, vmf); | |
3856 | if (ret & VM_FAULT_RETRY) | |
3857 | goto out_release; | |
3858 | ||
3859 | if (swapcache) { | |
3860 | /* | |
3861 | * Make sure folio_free_swap() or swapoff did not release the | |
3862 | * swapcache from under us. The page pin, and pte_same test | |
3863 | * below, are not enough to exclude that. Even if it is still | |
3864 | * swapcache, we need to check that the page's swap has not | |
3865 | * changed. | |
3866 | */ | |
3867 | if (unlikely(!folio_test_swapcache(folio) || | |
3868 | page_swap_entry(page).val != entry.val)) | |
3869 | goto out_page; | |
3870 | ||
3871 | /* | |
3872 | * KSM sometimes has to copy on read faults, for example, if | |
3873 | * page->index of !PageKSM() pages would be nonlinear inside the | |
3874 | * anon VMA -- PageKSM() is lost on actual swapout. | |
3875 | */ | |
3876 | page = ksm_might_need_to_copy(page, vma, vmf->address); | |
3877 | if (unlikely(!page)) { | |
3878 | ret = VM_FAULT_OOM; | |
3879 | goto out_page; | |
3880 | } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) { | |
3881 | ret = VM_FAULT_HWPOISON; | |
3882 | goto out_page; | |
3883 | } | |
3884 | folio = page_folio(page); | |
3885 | ||
3886 | /* | |
3887 | * If we want to map a page that's in the swapcache writable, we | |
3888 | * have to detect via the refcount if we're really the exclusive | |
3889 | * owner. Try removing the extra reference from the local LRU | |
3890 | * caches if required. | |
3891 | */ | |
3892 | if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache && | |
3893 | !folio_test_ksm(folio) && !folio_test_lru(folio)) | |
3894 | lru_add_drain(); | |
3895 | } | |
3896 | ||
3897 | folio_throttle_swaprate(folio, GFP_KERNEL); | |
3898 | ||
3899 | /* | |
3900 | * Back out if somebody else already faulted in this pte. | |
3901 | */ | |
3902 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, | |
3903 | &vmf->ptl); | |
3904 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) | |
3905 | goto out_nomap; | |
3906 | ||
3907 | if (unlikely(!folio_test_uptodate(folio))) { | |
3908 | ret = VM_FAULT_SIGBUS; | |
3909 | goto out_nomap; | |
3910 | } | |
3911 | ||
3912 | /* | |
3913 | * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte | |
3914 | * must never point at an anonymous page in the swapcache that is | |
3915 | * PG_anon_exclusive. Sanity check that this holds and especially, that | |
3916 | * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity | |
3917 | * check after taking the PT lock and making sure that nobody | |
3918 | * concurrently faulted in this page and set PG_anon_exclusive. | |
3919 | */ | |
3920 | BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio)); | |
3921 | BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page)); | |
3922 | ||
3923 | /* | |
3924 | * Check under PT lock (to protect against concurrent fork() sharing | |
3925 | * the swap entry concurrently) for certainly exclusive pages. | |
3926 | */ | |
3927 | if (!folio_test_ksm(folio)) { | |
3928 | exclusive = pte_swp_exclusive(vmf->orig_pte); | |
3929 | if (folio != swapcache) { | |
3930 | /* | |
3931 | * We have a fresh page that is not exposed to the | |
3932 | * swapcache -> certainly exclusive. | |
3933 | */ | |
3934 | exclusive = true; | |
3935 | } else if (exclusive && folio_test_writeback(folio) && | |
3936 | data_race(si->flags & SWP_STABLE_WRITES)) { | |
3937 | /* | |
3938 | * This is tricky: not all swap backends support | |
3939 | * concurrent page modifications while under writeback. | |
3940 | * | |
3941 | * So if we stumble over such a page in the swapcache | |
3942 | * we must not set the page exclusive, otherwise we can | |
3943 | * map it writable without further checks and modify it | |
3944 | * while still under writeback. | |
3945 | * | |
3946 | * For these problematic swap backends, simply drop the | |
3947 | * exclusive marker: this is perfectly fine as we start | |
3948 | * writeback only if we fully unmapped the page and | |
3949 | * there are no unexpected references on the page after | |
3950 | * unmapping succeeded. After fully unmapped, no | |
3951 | * further GUP references (FOLL_GET and FOLL_PIN) can | |
3952 | * appear, so dropping the exclusive marker and mapping | |
3953 | * it only R/O is fine. | |
3954 | */ | |
3955 | exclusive = false; | |
3956 | } | |
3957 | } | |
3958 | ||
3959 | /* | |
3960 | * Some architectures may have to restore extra metadata to the page | |
3961 | * when reading from swap. This metadata may be indexed by swap entry | |
3962 | * so this must be called before swap_free(). | |
3963 | */ | |
3964 | arch_swap_restore(entry, folio); | |
3965 | ||
3966 | /* | |
3967 | * Remove the swap entry and conditionally try to free up the swapcache. | |
3968 | * We're already holding a reference on the page but haven't mapped it | |
3969 | * yet. | |
3970 | */ | |
3971 | swap_free(entry); | |
3972 | if (should_try_to_free_swap(folio, vma, vmf->flags)) | |
3973 | folio_free_swap(folio); | |
3974 | ||
3975 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); | |
3976 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); | |
3977 | pte = mk_pte(page, vma->vm_page_prot); | |
3978 | ||
3979 | /* | |
3980 | * Same logic as in do_wp_page(); however, optimize for pages that are | |
3981 | * certainly not shared either because we just allocated them without | |
3982 | * exposing them to the swapcache or because the swap entry indicates | |
3983 | * exclusivity. | |
3984 | */ | |
3985 | if (!folio_test_ksm(folio) && | |
3986 | (exclusive || folio_ref_count(folio) == 1)) { | |
3987 | if (vmf->flags & FAULT_FLAG_WRITE) { | |
3988 | pte = maybe_mkwrite(pte_mkdirty(pte), vma); | |
3989 | vmf->flags &= ~FAULT_FLAG_WRITE; | |
3990 | } | |
3991 | rmap_flags |= RMAP_EXCLUSIVE; | |
3992 | } | |
3993 | flush_icache_page(vma, page); | |
3994 | if (pte_swp_soft_dirty(vmf->orig_pte)) | |
3995 | pte = pte_mksoft_dirty(pte); | |
3996 | if (pte_swp_uffd_wp(vmf->orig_pte)) | |
3997 | pte = pte_mkuffd_wp(pte); | |
3998 | vmf->orig_pte = pte; | |
3999 | ||
4000 | /* ksm created a completely new copy */ | |
4001 | if (unlikely(folio != swapcache && swapcache)) { | |
4002 | page_add_new_anon_rmap(page, vma, vmf->address); | |
4003 | folio_add_lru_vma(folio, vma); | |
4004 | } else { | |
4005 | page_add_anon_rmap(page, vma, vmf->address, rmap_flags); | |
4006 | } | |
4007 | ||
4008 | VM_BUG_ON(!folio_test_anon(folio) || | |
4009 | (pte_write(pte) && !PageAnonExclusive(page))); | |
4010 | set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); | |
4011 | arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte); | |
4012 | ||
4013 | folio_unlock(folio); | |
4014 | if (folio != swapcache && swapcache) { | |
4015 | /* | |
4016 | * Hold the lock to avoid the swap entry to be reused | |
4017 | * until we take the PT lock for the pte_same() check | |
4018 | * (to avoid false positives from pte_same). For | |
4019 | * further safety release the lock after the swap_free | |
4020 | * so that the swap count won't change under a | |
4021 | * parallel locked swapcache. | |
4022 | */ | |
4023 | folio_unlock(swapcache); | |
4024 | folio_put(swapcache); | |
4025 | } | |
4026 | ||
4027 | if (vmf->flags & FAULT_FLAG_WRITE) { | |
4028 | ret |= do_wp_page(vmf); | |
4029 | if (ret & VM_FAULT_ERROR) | |
4030 | ret &= VM_FAULT_ERROR; | |
4031 | goto out; | |
4032 | } | |
4033 | ||
4034 | /* No need to invalidate - it was non-present before */ | |
4035 | update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1); | |
4036 | unlock: | |
4037 | if (vmf->pte) | |
4038 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4039 | out: | |
4040 | if (si) | |
4041 | put_swap_device(si); | |
4042 | return ret; | |
4043 | out_nomap: | |
4044 | if (vmf->pte) | |
4045 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4046 | out_page: | |
4047 | folio_unlock(folio); | |
4048 | out_release: | |
4049 | folio_put(folio); | |
4050 | if (folio != swapcache && swapcache) { | |
4051 | folio_unlock(swapcache); | |
4052 | folio_put(swapcache); | |
4053 | } | |
4054 | if (si) | |
4055 | put_swap_device(si); | |
4056 | return ret; | |
4057 | } | |
4058 | ||
4059 | /* | |
4060 | * We enter with non-exclusive mmap_lock (to exclude vma changes, | |
4061 | * but allow concurrent faults), and pte mapped but not yet locked. | |
4062 | * We return with mmap_lock still held, but pte unmapped and unlocked. | |
4063 | */ | |
4064 | static vm_fault_t do_anonymous_page(struct vm_fault *vmf) | |
4065 | { | |
4066 | bool uffd_wp = vmf_orig_pte_uffd_wp(vmf); | |
4067 | struct vm_area_struct *vma = vmf->vma; | |
4068 | struct folio *folio; | |
4069 | vm_fault_t ret = 0; | |
4070 | pte_t entry; | |
4071 | ||
4072 | /* File mapping without ->vm_ops ? */ | |
4073 | if (vma->vm_flags & VM_SHARED) | |
4074 | return VM_FAULT_SIGBUS; | |
4075 | ||
4076 | /* | |
4077 | * Use pte_alloc() instead of pte_alloc_map(), so that OOM can | |
4078 | * be distinguished from a transient failure of pte_offset_map(). | |
4079 | */ | |
4080 | if (pte_alloc(vma->vm_mm, vmf->pmd)) | |
4081 | return VM_FAULT_OOM; | |
4082 | ||
4083 | /* Use the zero-page for reads */ | |
4084 | if (!(vmf->flags & FAULT_FLAG_WRITE) && | |
4085 | !mm_forbids_zeropage(vma->vm_mm)) { | |
4086 | entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), | |
4087 | vma->vm_page_prot)); | |
4088 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, | |
4089 | vmf->address, &vmf->ptl); | |
4090 | if (!vmf->pte) | |
4091 | goto unlock; | |
4092 | if (vmf_pte_changed(vmf)) { | |
4093 | update_mmu_tlb(vma, vmf->address, vmf->pte); | |
4094 | goto unlock; | |
4095 | } | |
4096 | ret = check_stable_address_space(vma->vm_mm); | |
4097 | if (ret) | |
4098 | goto unlock; | |
4099 | /* Deliver the page fault to userland, check inside PT lock */ | |
4100 | if (userfaultfd_missing(vma)) { | |
4101 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4102 | return handle_userfault(vmf, VM_UFFD_MISSING); | |
4103 | } | |
4104 | goto setpte; | |
4105 | } | |
4106 | ||
4107 | /* Allocate our own private page. */ | |
4108 | if (unlikely(anon_vma_prepare(vma))) | |
4109 | goto oom; | |
4110 | folio = vma_alloc_zeroed_movable_folio(vma, vmf->address); | |
4111 | if (!folio) | |
4112 | goto oom; | |
4113 | ||
4114 | if (mem_cgroup_charge(folio, vma->vm_mm, GFP_KERNEL)) | |
4115 | goto oom_free_page; | |
4116 | folio_throttle_swaprate(folio, GFP_KERNEL); | |
4117 | ||
4118 | /* | |
4119 | * The memory barrier inside __folio_mark_uptodate makes sure that | |
4120 | * preceding stores to the page contents become visible before | |
4121 | * the set_pte_at() write. | |
4122 | */ | |
4123 | __folio_mark_uptodate(folio); | |
4124 | ||
4125 | entry = mk_pte(&folio->page, vma->vm_page_prot); | |
4126 | entry = pte_sw_mkyoung(entry); | |
4127 | if (vma->vm_flags & VM_WRITE) | |
4128 | entry = pte_mkwrite(pte_mkdirty(entry), vma); | |
4129 | ||
4130 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, | |
4131 | &vmf->ptl); | |
4132 | if (!vmf->pte) | |
4133 | goto release; | |
4134 | if (vmf_pte_changed(vmf)) { | |
4135 | update_mmu_tlb(vma, vmf->address, vmf->pte); | |
4136 | goto release; | |
4137 | } | |
4138 | ||
4139 | ret = check_stable_address_space(vma->vm_mm); | |
4140 | if (ret) | |
4141 | goto release; | |
4142 | ||
4143 | /* Deliver the page fault to userland, check inside PT lock */ | |
4144 | if (userfaultfd_missing(vma)) { | |
4145 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4146 | folio_put(folio); | |
4147 | return handle_userfault(vmf, VM_UFFD_MISSING); | |
4148 | } | |
4149 | ||
4150 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); | |
4151 | folio_add_new_anon_rmap(folio, vma, vmf->address); | |
4152 | folio_add_lru_vma(folio, vma); | |
4153 | setpte: | |
4154 | if (uffd_wp) | |
4155 | entry = pte_mkuffd_wp(entry); | |
4156 | set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); | |
4157 | ||
4158 | /* No need to invalidate - it was non-present before */ | |
4159 | update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1); | |
4160 | unlock: | |
4161 | if (vmf->pte) | |
4162 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4163 | return ret; | |
4164 | release: | |
4165 | folio_put(folio); | |
4166 | goto unlock; | |
4167 | oom_free_page: | |
4168 | folio_put(folio); | |
4169 | oom: | |
4170 | return VM_FAULT_OOM; | |
4171 | } | |
4172 | ||
4173 | /* | |
4174 | * The mmap_lock must have been held on entry, and may have been | |
4175 | * released depending on flags and vma->vm_ops->fault() return value. | |
4176 | * See filemap_fault() and __lock_page_retry(). | |
4177 | */ | |
4178 | static vm_fault_t __do_fault(struct vm_fault *vmf) | |
4179 | { | |
4180 | struct vm_area_struct *vma = vmf->vma; | |
4181 | vm_fault_t ret; | |
4182 | ||
4183 | /* | |
4184 | * Preallocate pte before we take page_lock because this might lead to | |
4185 | * deadlocks for memcg reclaim which waits for pages under writeback: | |
4186 | * lock_page(A) | |
4187 | * SetPageWriteback(A) | |
4188 | * unlock_page(A) | |
4189 | * lock_page(B) | |
4190 | * lock_page(B) | |
4191 | * pte_alloc_one | |
4192 | * shrink_page_list | |
4193 | * wait_on_page_writeback(A) | |
4194 | * SetPageWriteback(B) | |
4195 | * unlock_page(B) | |
4196 | * # flush A, B to clear the writeback | |
4197 | */ | |
4198 | if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) { | |
4199 | vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); | |
4200 | if (!vmf->prealloc_pte) | |
4201 | return VM_FAULT_OOM; | |
4202 | } | |
4203 | ||
4204 | ret = vma->vm_ops->fault(vmf); | |
4205 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | | |
4206 | VM_FAULT_DONE_COW))) | |
4207 | return ret; | |
4208 | ||
4209 | if (unlikely(PageHWPoison(vmf->page))) { | |
4210 | struct page *page = vmf->page; | |
4211 | vm_fault_t poisonret = VM_FAULT_HWPOISON; | |
4212 | if (ret & VM_FAULT_LOCKED) { | |
4213 | if (page_mapped(page)) | |
4214 | unmap_mapping_pages(page_mapping(page), | |
4215 | page->index, 1, false); | |
4216 | /* Retry if a clean page was removed from the cache. */ | |
4217 | if (invalidate_inode_page(page)) | |
4218 | poisonret = VM_FAULT_NOPAGE; | |
4219 | unlock_page(page); | |
4220 | } | |
4221 | put_page(page); | |
4222 | vmf->page = NULL; | |
4223 | return poisonret; | |
4224 | } | |
4225 | ||
4226 | if (unlikely(!(ret & VM_FAULT_LOCKED))) | |
4227 | lock_page(vmf->page); | |
4228 | else | |
4229 | VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); | |
4230 | ||
4231 | return ret; | |
4232 | } | |
4233 | ||
4234 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
4235 | static void deposit_prealloc_pte(struct vm_fault *vmf) | |
4236 | { | |
4237 | struct vm_area_struct *vma = vmf->vma; | |
4238 | ||
4239 | pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); | |
4240 | /* | |
4241 | * We are going to consume the prealloc table, | |
4242 | * count that as nr_ptes. | |
4243 | */ | |
4244 | mm_inc_nr_ptes(vma->vm_mm); | |
4245 | vmf->prealloc_pte = NULL; | |
4246 | } | |
4247 | ||
4248 | vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) | |
4249 | { | |
4250 | struct vm_area_struct *vma = vmf->vma; | |
4251 | bool write = vmf->flags & FAULT_FLAG_WRITE; | |
4252 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
4253 | pmd_t entry; | |
4254 | vm_fault_t ret = VM_FAULT_FALLBACK; | |
4255 | ||
4256 | if (!transhuge_vma_suitable(vma, haddr)) | |
4257 | return ret; | |
4258 | ||
4259 | page = compound_head(page); | |
4260 | if (compound_order(page) != HPAGE_PMD_ORDER) | |
4261 | return ret; | |
4262 | ||
4263 | /* | |
4264 | * Just backoff if any subpage of a THP is corrupted otherwise | |
4265 | * the corrupted page may mapped by PMD silently to escape the | |
4266 | * check. This kind of THP just can be PTE mapped. Access to | |
4267 | * the corrupted subpage should trigger SIGBUS as expected. | |
4268 | */ | |
4269 | if (unlikely(PageHasHWPoisoned(page))) | |
4270 | return ret; | |
4271 | ||
4272 | /* | |
4273 | * Archs like ppc64 need additional space to store information | |
4274 | * related to pte entry. Use the preallocated table for that. | |
4275 | */ | |
4276 | if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { | |
4277 | vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); | |
4278 | if (!vmf->prealloc_pte) | |
4279 | return VM_FAULT_OOM; | |
4280 | } | |
4281 | ||
4282 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); | |
4283 | if (unlikely(!pmd_none(*vmf->pmd))) | |
4284 | goto out; | |
4285 | ||
4286 | flush_icache_pages(vma, page, HPAGE_PMD_NR); | |
4287 | ||
4288 | entry = mk_huge_pmd(page, vma->vm_page_prot); | |
4289 | if (write) | |
4290 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
4291 | ||
4292 | add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR); | |
4293 | page_add_file_rmap(page, vma, true); | |
4294 | ||
4295 | /* | |
4296 | * deposit and withdraw with pmd lock held | |
4297 | */ | |
4298 | if (arch_needs_pgtable_deposit()) | |
4299 | deposit_prealloc_pte(vmf); | |
4300 | ||
4301 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); | |
4302 | ||
4303 | update_mmu_cache_pmd(vma, haddr, vmf->pmd); | |
4304 | ||
4305 | /* fault is handled */ | |
4306 | ret = 0; | |
4307 | count_vm_event(THP_FILE_MAPPED); | |
4308 | out: | |
4309 | spin_unlock(vmf->ptl); | |
4310 | return ret; | |
4311 | } | |
4312 | #else | |
4313 | vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) | |
4314 | { | |
4315 | return VM_FAULT_FALLBACK; | |
4316 | } | |
4317 | #endif | |
4318 | ||
4319 | /** | |
4320 | * set_pte_range - Set a range of PTEs to point to pages in a folio. | |
4321 | * @vmf: Fault decription. | |
4322 | * @folio: The folio that contains @page. | |
4323 | * @page: The first page to create a PTE for. | |
4324 | * @nr: The number of PTEs to create. | |
4325 | * @addr: The first address to create a PTE for. | |
4326 | */ | |
4327 | void set_pte_range(struct vm_fault *vmf, struct folio *folio, | |
4328 | struct page *page, unsigned int nr, unsigned long addr) | |
4329 | { | |
4330 | struct vm_area_struct *vma = vmf->vma; | |
4331 | bool uffd_wp = vmf_orig_pte_uffd_wp(vmf); | |
4332 | bool write = vmf->flags & FAULT_FLAG_WRITE; | |
4333 | bool prefault = in_range(vmf->address, addr, nr * PAGE_SIZE); | |
4334 | pte_t entry; | |
4335 | ||
4336 | flush_icache_pages(vma, page, nr); | |
4337 | entry = mk_pte(page, vma->vm_page_prot); | |
4338 | ||
4339 | if (prefault && arch_wants_old_prefaulted_pte()) | |
4340 | entry = pte_mkold(entry); | |
4341 | else | |
4342 | entry = pte_sw_mkyoung(entry); | |
4343 | ||
4344 | if (write) | |
4345 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
4346 | if (unlikely(uffd_wp)) | |
4347 | entry = pte_mkuffd_wp(entry); | |
4348 | /* copy-on-write page */ | |
4349 | if (write && !(vma->vm_flags & VM_SHARED)) { | |
4350 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr); | |
4351 | VM_BUG_ON_FOLIO(nr != 1, folio); | |
4352 | folio_add_new_anon_rmap(folio, vma, addr); | |
4353 | folio_add_lru_vma(folio, vma); | |
4354 | } else { | |
4355 | add_mm_counter(vma->vm_mm, mm_counter_file(page), nr); | |
4356 | folio_add_file_rmap_range(folio, page, nr, vma, false); | |
4357 | } | |
4358 | set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr); | |
4359 | ||
4360 | /* no need to invalidate: a not-present page won't be cached */ | |
4361 | update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr); | |
4362 | } | |
4363 | ||
4364 | static bool vmf_pte_changed(struct vm_fault *vmf) | |
4365 | { | |
4366 | if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID) | |
4367 | return !pte_same(ptep_get(vmf->pte), vmf->orig_pte); | |
4368 | ||
4369 | return !pte_none(ptep_get(vmf->pte)); | |
4370 | } | |
4371 | ||
4372 | /** | |
4373 | * finish_fault - finish page fault once we have prepared the page to fault | |
4374 | * | |
4375 | * @vmf: structure describing the fault | |
4376 | * | |
4377 | * This function handles all that is needed to finish a page fault once the | |
4378 | * page to fault in is prepared. It handles locking of PTEs, inserts PTE for | |
4379 | * given page, adds reverse page mapping, handles memcg charges and LRU | |
4380 | * addition. | |
4381 | * | |
4382 | * The function expects the page to be locked and on success it consumes a | |
4383 | * reference of a page being mapped (for the PTE which maps it). | |
4384 | * | |
4385 | * Return: %0 on success, %VM_FAULT_ code in case of error. | |
4386 | */ | |
4387 | vm_fault_t finish_fault(struct vm_fault *vmf) | |
4388 | { | |
4389 | struct vm_area_struct *vma = vmf->vma; | |
4390 | struct page *page; | |
4391 | vm_fault_t ret; | |
4392 | ||
4393 | /* Did we COW the page? */ | |
4394 | if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) | |
4395 | page = vmf->cow_page; | |
4396 | else | |
4397 | page = vmf->page; | |
4398 | ||
4399 | /* | |
4400 | * check even for read faults because we might have lost our CoWed | |
4401 | * page | |
4402 | */ | |
4403 | if (!(vma->vm_flags & VM_SHARED)) { | |
4404 | ret = check_stable_address_space(vma->vm_mm); | |
4405 | if (ret) | |
4406 | return ret; | |
4407 | } | |
4408 | ||
4409 | if (pmd_none(*vmf->pmd)) { | |
4410 | if (PageTransCompound(page)) { | |
4411 | ret = do_set_pmd(vmf, page); | |
4412 | if (ret != VM_FAULT_FALLBACK) | |
4413 | return ret; | |
4414 | } | |
4415 | ||
4416 | if (vmf->prealloc_pte) | |
4417 | pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte); | |
4418 | else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) | |
4419 | return VM_FAULT_OOM; | |
4420 | } | |
4421 | ||
4422 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, | |
4423 | vmf->address, &vmf->ptl); | |
4424 | if (!vmf->pte) | |
4425 | return VM_FAULT_NOPAGE; | |
4426 | ||
4427 | /* Re-check under ptl */ | |
4428 | if (likely(!vmf_pte_changed(vmf))) { | |
4429 | struct folio *folio = page_folio(page); | |
4430 | ||
4431 | set_pte_range(vmf, folio, page, 1, vmf->address); | |
4432 | ret = 0; | |
4433 | } else { | |
4434 | update_mmu_tlb(vma, vmf->address, vmf->pte); | |
4435 | ret = VM_FAULT_NOPAGE; | |
4436 | } | |
4437 | ||
4438 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4439 | return ret; | |
4440 | } | |
4441 | ||
4442 | static unsigned long fault_around_pages __read_mostly = | |
4443 | 65536 >> PAGE_SHIFT; | |
4444 | ||
4445 | #ifdef CONFIG_DEBUG_FS | |
4446 | static int fault_around_bytes_get(void *data, u64 *val) | |
4447 | { | |
4448 | *val = fault_around_pages << PAGE_SHIFT; | |
4449 | return 0; | |
4450 | } | |
4451 | ||
4452 | /* | |
4453 | * fault_around_bytes must be rounded down to the nearest page order as it's | |
4454 | * what do_fault_around() expects to see. | |
4455 | */ | |
4456 | static int fault_around_bytes_set(void *data, u64 val) | |
4457 | { | |
4458 | if (val / PAGE_SIZE > PTRS_PER_PTE) | |
4459 | return -EINVAL; | |
4460 | ||
4461 | /* | |
4462 | * The minimum value is 1 page, however this results in no fault-around | |
4463 | * at all. See should_fault_around(). | |
4464 | */ | |
4465 | fault_around_pages = max(rounddown_pow_of_two(val) >> PAGE_SHIFT, 1UL); | |
4466 | ||
4467 | return 0; | |
4468 | } | |
4469 | DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, | |
4470 | fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); | |
4471 | ||
4472 | static int __init fault_around_debugfs(void) | |
4473 | { | |
4474 | debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL, | |
4475 | &fault_around_bytes_fops); | |
4476 | return 0; | |
4477 | } | |
4478 | late_initcall(fault_around_debugfs); | |
4479 | #endif | |
4480 | ||
4481 | /* | |
4482 | * do_fault_around() tries to map few pages around the fault address. The hope | |
4483 | * is that the pages will be needed soon and this will lower the number of | |
4484 | * faults to handle. | |
4485 | * | |
4486 | * It uses vm_ops->map_pages() to map the pages, which skips the page if it's | |
4487 | * not ready to be mapped: not up-to-date, locked, etc. | |
4488 | * | |
4489 | * This function doesn't cross VMA or page table boundaries, in order to call | |
4490 | * map_pages() and acquire a PTE lock only once. | |
4491 | * | |
4492 | * fault_around_pages defines how many pages we'll try to map. | |
4493 | * do_fault_around() expects it to be set to a power of two less than or equal | |
4494 | * to PTRS_PER_PTE. | |
4495 | * | |
4496 | * The virtual address of the area that we map is naturally aligned to | |
4497 | * fault_around_pages * PAGE_SIZE rounded down to the machine page size | |
4498 | * (and therefore to page order). This way it's easier to guarantee | |
4499 | * that we don't cross page table boundaries. | |
4500 | */ | |
4501 | static vm_fault_t do_fault_around(struct vm_fault *vmf) | |
4502 | { | |
4503 | pgoff_t nr_pages = READ_ONCE(fault_around_pages); | |
4504 | pgoff_t pte_off = pte_index(vmf->address); | |
4505 | /* The page offset of vmf->address within the VMA. */ | |
4506 | pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; | |
4507 | pgoff_t from_pte, to_pte; | |
4508 | vm_fault_t ret; | |
4509 | ||
4510 | /* The PTE offset of the start address, clamped to the VMA. */ | |
4511 | from_pte = max(ALIGN_DOWN(pte_off, nr_pages), | |
4512 | pte_off - min(pte_off, vma_off)); | |
4513 | ||
4514 | /* The PTE offset of the end address, clamped to the VMA and PTE. */ | |
4515 | to_pte = min3(from_pte + nr_pages, (pgoff_t)PTRS_PER_PTE, | |
4516 | pte_off + vma_pages(vmf->vma) - vma_off) - 1; | |
4517 | ||
4518 | if (pmd_none(*vmf->pmd)) { | |
4519 | vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); | |
4520 | if (!vmf->prealloc_pte) | |
4521 | return VM_FAULT_OOM; | |
4522 | } | |
4523 | ||
4524 | rcu_read_lock(); | |
4525 | ret = vmf->vma->vm_ops->map_pages(vmf, | |
4526 | vmf->pgoff + from_pte - pte_off, | |
4527 | vmf->pgoff + to_pte - pte_off); | |
4528 | rcu_read_unlock(); | |
4529 | ||
4530 | return ret; | |
4531 | } | |
4532 | ||
4533 | /* Return true if we should do read fault-around, false otherwise */ | |
4534 | static inline bool should_fault_around(struct vm_fault *vmf) | |
4535 | { | |
4536 | /* No ->map_pages? No way to fault around... */ | |
4537 | if (!vmf->vma->vm_ops->map_pages) | |
4538 | return false; | |
4539 | ||
4540 | if (uffd_disable_fault_around(vmf->vma)) | |
4541 | return false; | |
4542 | ||
4543 | /* A single page implies no faulting 'around' at all. */ | |
4544 | return fault_around_pages > 1; | |
4545 | } | |
4546 | ||
4547 | static vm_fault_t do_read_fault(struct vm_fault *vmf) | |
4548 | { | |
4549 | vm_fault_t ret = 0; | |
4550 | struct folio *folio; | |
4551 | ||
4552 | /* | |
4553 | * Let's call ->map_pages() first and use ->fault() as fallback | |
4554 | * if page by the offset is not ready to be mapped (cold cache or | |
4555 | * something). | |
4556 | */ | |
4557 | if (should_fault_around(vmf)) { | |
4558 | ret = do_fault_around(vmf); | |
4559 | if (ret) | |
4560 | return ret; | |
4561 | } | |
4562 | ||
4563 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
4564 | vma_end_read(vmf->vma); | |
4565 | return VM_FAULT_RETRY; | |
4566 | } | |
4567 | ||
4568 | ret = __do_fault(vmf); | |
4569 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) | |
4570 | return ret; | |
4571 | ||
4572 | ret |= finish_fault(vmf); | |
4573 | folio = page_folio(vmf->page); | |
4574 | folio_unlock(folio); | |
4575 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) | |
4576 | folio_put(folio); | |
4577 | return ret; | |
4578 | } | |
4579 | ||
4580 | static vm_fault_t do_cow_fault(struct vm_fault *vmf) | |
4581 | { | |
4582 | struct vm_area_struct *vma = vmf->vma; | |
4583 | vm_fault_t ret; | |
4584 | ||
4585 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
4586 | vma_end_read(vma); | |
4587 | return VM_FAULT_RETRY; | |
4588 | } | |
4589 | ||
4590 | if (unlikely(anon_vma_prepare(vma))) | |
4591 | return VM_FAULT_OOM; | |
4592 | ||
4593 | vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); | |
4594 | if (!vmf->cow_page) | |
4595 | return VM_FAULT_OOM; | |
4596 | ||
4597 | if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm, | |
4598 | GFP_KERNEL)) { | |
4599 | put_page(vmf->cow_page); | |
4600 | return VM_FAULT_OOM; | |
4601 | } | |
4602 | folio_throttle_swaprate(page_folio(vmf->cow_page), GFP_KERNEL); | |
4603 | ||
4604 | ret = __do_fault(vmf); | |
4605 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) | |
4606 | goto uncharge_out; | |
4607 | if (ret & VM_FAULT_DONE_COW) | |
4608 | return ret; | |
4609 | ||
4610 | copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); | |
4611 | __SetPageUptodate(vmf->cow_page); | |
4612 | ||
4613 | ret |= finish_fault(vmf); | |
4614 | unlock_page(vmf->page); | |
4615 | put_page(vmf->page); | |
4616 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) | |
4617 | goto uncharge_out; | |
4618 | return ret; | |
4619 | uncharge_out: | |
4620 | put_page(vmf->cow_page); | |
4621 | return ret; | |
4622 | } | |
4623 | ||
4624 | static vm_fault_t do_shared_fault(struct vm_fault *vmf) | |
4625 | { | |
4626 | struct vm_area_struct *vma = vmf->vma; | |
4627 | vm_fault_t ret, tmp; | |
4628 | struct folio *folio; | |
4629 | ||
4630 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { | |
4631 | vma_end_read(vma); | |
4632 | return VM_FAULT_RETRY; | |
4633 | } | |
4634 | ||
4635 | ret = __do_fault(vmf); | |
4636 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) | |
4637 | return ret; | |
4638 | ||
4639 | folio = page_folio(vmf->page); | |
4640 | ||
4641 | /* | |
4642 | * Check if the backing address space wants to know that the page is | |
4643 | * about to become writable | |
4644 | */ | |
4645 | if (vma->vm_ops->page_mkwrite) { | |
4646 | folio_unlock(folio); | |
4647 | tmp = do_page_mkwrite(vmf, folio); | |
4648 | if (unlikely(!tmp || | |
4649 | (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { | |
4650 | folio_put(folio); | |
4651 | return tmp; | |
4652 | } | |
4653 | } | |
4654 | ||
4655 | ret |= finish_fault(vmf); | |
4656 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | | |
4657 | VM_FAULT_RETRY))) { | |
4658 | folio_unlock(folio); | |
4659 | folio_put(folio); | |
4660 | return ret; | |
4661 | } | |
4662 | ||
4663 | ret |= fault_dirty_shared_page(vmf); | |
4664 | return ret; | |
4665 | } | |
4666 | ||
4667 | /* | |
4668 | * We enter with non-exclusive mmap_lock (to exclude vma changes, | |
4669 | * but allow concurrent faults). | |
4670 | * The mmap_lock may have been released depending on flags and our | |
4671 | * return value. See filemap_fault() and __folio_lock_or_retry(). | |
4672 | * If mmap_lock is released, vma may become invalid (for example | |
4673 | * by other thread calling munmap()). | |
4674 | */ | |
4675 | static vm_fault_t do_fault(struct vm_fault *vmf) | |
4676 | { | |
4677 | struct vm_area_struct *vma = vmf->vma; | |
4678 | struct mm_struct *vm_mm = vma->vm_mm; | |
4679 | vm_fault_t ret; | |
4680 | ||
4681 | /* | |
4682 | * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND | |
4683 | */ | |
4684 | if (!vma->vm_ops->fault) { | |
4685 | vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, | |
4686 | vmf->address, &vmf->ptl); | |
4687 | if (unlikely(!vmf->pte)) | |
4688 | ret = VM_FAULT_SIGBUS; | |
4689 | else { | |
4690 | /* | |
4691 | * Make sure this is not a temporary clearing of pte | |
4692 | * by holding ptl and checking again. A R/M/W update | |
4693 | * of pte involves: take ptl, clearing the pte so that | |
4694 | * we don't have concurrent modification by hardware | |
4695 | * followed by an update. | |
4696 | */ | |
4697 | if (unlikely(pte_none(ptep_get(vmf->pte)))) | |
4698 | ret = VM_FAULT_SIGBUS; | |
4699 | else | |
4700 | ret = VM_FAULT_NOPAGE; | |
4701 | ||
4702 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4703 | } | |
4704 | } else if (!(vmf->flags & FAULT_FLAG_WRITE)) | |
4705 | ret = do_read_fault(vmf); | |
4706 | else if (!(vma->vm_flags & VM_SHARED)) | |
4707 | ret = do_cow_fault(vmf); | |
4708 | else | |
4709 | ret = do_shared_fault(vmf); | |
4710 | ||
4711 | /* preallocated pagetable is unused: free it */ | |
4712 | if (vmf->prealloc_pte) { | |
4713 | pte_free(vm_mm, vmf->prealloc_pte); | |
4714 | vmf->prealloc_pte = NULL; | |
4715 | } | |
4716 | return ret; | |
4717 | } | |
4718 | ||
4719 | int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, | |
4720 | unsigned long addr, int page_nid, int *flags) | |
4721 | { | |
4722 | get_page(page); | |
4723 | ||
4724 | /* Record the current PID acceesing VMA */ | |
4725 | vma_set_access_pid_bit(vma); | |
4726 | ||
4727 | count_vm_numa_event(NUMA_HINT_FAULTS); | |
4728 | if (page_nid == numa_node_id()) { | |
4729 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); | |
4730 | *flags |= TNF_FAULT_LOCAL; | |
4731 | } | |
4732 | ||
4733 | return mpol_misplaced(page, vma, addr); | |
4734 | } | |
4735 | ||
4736 | static vm_fault_t do_numa_page(struct vm_fault *vmf) | |
4737 | { | |
4738 | struct vm_area_struct *vma = vmf->vma; | |
4739 | struct page *page = NULL; | |
4740 | int page_nid = NUMA_NO_NODE; | |
4741 | bool writable = false; | |
4742 | int last_cpupid; | |
4743 | int target_nid; | |
4744 | pte_t pte, old_pte; | |
4745 | int flags = 0; | |
4746 | ||
4747 | /* | |
4748 | * The "pte" at this point cannot be used safely without | |
4749 | * validation through pte_unmap_same(). It's of NUMA type but | |
4750 | * the pfn may be screwed if the read is non atomic. | |
4751 | */ | |
4752 | spin_lock(vmf->ptl); | |
4753 | if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { | |
4754 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4755 | goto out; | |
4756 | } | |
4757 | ||
4758 | /* Get the normal PTE */ | |
4759 | old_pte = ptep_get(vmf->pte); | |
4760 | pte = pte_modify(old_pte, vma->vm_page_prot); | |
4761 | ||
4762 | /* | |
4763 | * Detect now whether the PTE could be writable; this information | |
4764 | * is only valid while holding the PT lock. | |
4765 | */ | |
4766 | writable = pte_write(pte); | |
4767 | if (!writable && vma_wants_manual_pte_write_upgrade(vma) && | |
4768 | can_change_pte_writable(vma, vmf->address, pte)) | |
4769 | writable = true; | |
4770 | ||
4771 | page = vm_normal_page(vma, vmf->address, pte); | |
4772 | if (!page || is_zone_device_page(page)) | |
4773 | goto out_map; | |
4774 | ||
4775 | /* TODO: handle PTE-mapped THP */ | |
4776 | if (PageCompound(page)) | |
4777 | goto out_map; | |
4778 | ||
4779 | /* | |
4780 | * Avoid grouping on RO pages in general. RO pages shouldn't hurt as | |
4781 | * much anyway since they can be in shared cache state. This misses | |
4782 | * the case where a mapping is writable but the process never writes | |
4783 | * to it but pte_write gets cleared during protection updates and | |
4784 | * pte_dirty has unpredictable behaviour between PTE scan updates, | |
4785 | * background writeback, dirty balancing and application behaviour. | |
4786 | */ | |
4787 | if (!writable) | |
4788 | flags |= TNF_NO_GROUP; | |
4789 | ||
4790 | /* | |
4791 | * Flag if the page is shared between multiple address spaces. This | |
4792 | * is later used when determining whether to group tasks together | |
4793 | */ | |
4794 | if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) | |
4795 | flags |= TNF_SHARED; | |
4796 | ||
4797 | page_nid = page_to_nid(page); | |
4798 | /* | |
4799 | * For memory tiering mode, cpupid of slow memory page is used | |
4800 | * to record page access time. So use default value. | |
4801 | */ | |
4802 | if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) && | |
4803 | !node_is_toptier(page_nid)) | |
4804 | last_cpupid = (-1 & LAST_CPUPID_MASK); | |
4805 | else | |
4806 | last_cpupid = page_cpupid_last(page); | |
4807 | target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid, | |
4808 | &flags); | |
4809 | if (target_nid == NUMA_NO_NODE) { | |
4810 | put_page(page); | |
4811 | goto out_map; | |
4812 | } | |
4813 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4814 | writable = false; | |
4815 | ||
4816 | /* Migrate to the requested node */ | |
4817 | if (migrate_misplaced_page(page, vma, target_nid)) { | |
4818 | page_nid = target_nid; | |
4819 | flags |= TNF_MIGRATED; | |
4820 | } else { | |
4821 | flags |= TNF_MIGRATE_FAIL; | |
4822 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, | |
4823 | vmf->address, &vmf->ptl); | |
4824 | if (unlikely(!vmf->pte)) | |
4825 | goto out; | |
4826 | if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { | |
4827 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4828 | goto out; | |
4829 | } | |
4830 | goto out_map; | |
4831 | } | |
4832 | ||
4833 | out: | |
4834 | if (page_nid != NUMA_NO_NODE) | |
4835 | task_numa_fault(last_cpupid, page_nid, 1, flags); | |
4836 | return 0; | |
4837 | out_map: | |
4838 | /* | |
4839 | * Make it present again, depending on how arch implements | |
4840 | * non-accessible ptes, some can allow access by kernel mode. | |
4841 | */ | |
4842 | old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte); | |
4843 | pte = pte_modify(old_pte, vma->vm_page_prot); | |
4844 | pte = pte_mkyoung(pte); | |
4845 | if (writable) | |
4846 | pte = pte_mkwrite(pte, vma); | |
4847 | ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte); | |
4848 | update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1); | |
4849 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
4850 | goto out; | |
4851 | } | |
4852 | ||
4853 | static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) | |
4854 | { | |
4855 | struct vm_area_struct *vma = vmf->vma; | |
4856 | if (vma_is_anonymous(vma)) | |
4857 | return do_huge_pmd_anonymous_page(vmf); | |
4858 | if (vma->vm_ops->huge_fault) | |
4859 | return vma->vm_ops->huge_fault(vmf, PMD_ORDER); | |
4860 | return VM_FAULT_FALLBACK; | |
4861 | } | |
4862 | ||
4863 | /* `inline' is required to avoid gcc 4.1.2 build error */ | |
4864 | static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) | |
4865 | { | |
4866 | struct vm_area_struct *vma = vmf->vma; | |
4867 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; | |
4868 | vm_fault_t ret; | |
4869 | ||
4870 | if (vma_is_anonymous(vma)) { | |
4871 | if (likely(!unshare) && | |
4872 | userfaultfd_huge_pmd_wp(vma, vmf->orig_pmd)) | |
4873 | return handle_userfault(vmf, VM_UFFD_WP); | |
4874 | return do_huge_pmd_wp_page(vmf); | |
4875 | } | |
4876 | ||
4877 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { | |
4878 | if (vma->vm_ops->huge_fault) { | |
4879 | ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER); | |
4880 | if (!(ret & VM_FAULT_FALLBACK)) | |
4881 | return ret; | |
4882 | } | |
4883 | } | |
4884 | ||
4885 | /* COW or write-notify handled on pte level: split pmd. */ | |
4886 | __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); | |
4887 | ||
4888 | return VM_FAULT_FALLBACK; | |
4889 | } | |
4890 | ||
4891 | static vm_fault_t create_huge_pud(struct vm_fault *vmf) | |
4892 | { | |
4893 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ | |
4894 | defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) | |
4895 | struct vm_area_struct *vma = vmf->vma; | |
4896 | /* No support for anonymous transparent PUD pages yet */ | |
4897 | if (vma_is_anonymous(vma)) | |
4898 | return VM_FAULT_FALLBACK; | |
4899 | if (vma->vm_ops->huge_fault) | |
4900 | return vma->vm_ops->huge_fault(vmf, PUD_ORDER); | |
4901 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | |
4902 | return VM_FAULT_FALLBACK; | |
4903 | } | |
4904 | ||
4905 | static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) | |
4906 | { | |
4907 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ | |
4908 | defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) | |
4909 | struct vm_area_struct *vma = vmf->vma; | |
4910 | vm_fault_t ret; | |
4911 | ||
4912 | /* No support for anonymous transparent PUD pages yet */ | |
4913 | if (vma_is_anonymous(vma)) | |
4914 | goto split; | |
4915 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { | |
4916 | if (vma->vm_ops->huge_fault) { | |
4917 | ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER); | |
4918 | if (!(ret & VM_FAULT_FALLBACK)) | |
4919 | return ret; | |
4920 | } | |
4921 | } | |
4922 | split: | |
4923 | /* COW or write-notify not handled on PUD level: split pud.*/ | |
4924 | __split_huge_pud(vma, vmf->pud, vmf->address); | |
4925 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
4926 | return VM_FAULT_FALLBACK; | |
4927 | } | |
4928 | ||
4929 | /* | |
4930 | * These routines also need to handle stuff like marking pages dirty | |
4931 | * and/or accessed for architectures that don't do it in hardware (most | |
4932 | * RISC architectures). The early dirtying is also good on the i386. | |
4933 | * | |
4934 | * There is also a hook called "update_mmu_cache()" that architectures | |
4935 | * with external mmu caches can use to update those (ie the Sparc or | |
4936 | * PowerPC hashed page tables that act as extended TLBs). | |
4937 | * | |
4938 | * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow | |
4939 | * concurrent faults). | |
4940 | * | |
4941 | * The mmap_lock may have been released depending on flags and our return value. | |
4942 | * See filemap_fault() and __folio_lock_or_retry(). | |
4943 | */ | |
4944 | static vm_fault_t handle_pte_fault(struct vm_fault *vmf) | |
4945 | { | |
4946 | pte_t entry; | |
4947 | ||
4948 | if (unlikely(pmd_none(*vmf->pmd))) { | |
4949 | /* | |
4950 | * Leave __pte_alloc() until later: because vm_ops->fault may | |
4951 | * want to allocate huge page, and if we expose page table | |
4952 | * for an instant, it will be difficult to retract from | |
4953 | * concurrent faults and from rmap lookups. | |
4954 | */ | |
4955 | vmf->pte = NULL; | |
4956 | vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID; | |
4957 | } else { | |
4958 | /* | |
4959 | * A regular pmd is established and it can't morph into a huge | |
4960 | * pmd by anon khugepaged, since that takes mmap_lock in write | |
4961 | * mode; but shmem or file collapse to THP could still morph | |
4962 | * it into a huge pmd: just retry later if so. | |
4963 | */ | |
4964 | vmf->pte = pte_offset_map_nolock(vmf->vma->vm_mm, vmf->pmd, | |
4965 | vmf->address, &vmf->ptl); | |
4966 | if (unlikely(!vmf->pte)) | |
4967 | return 0; | |
4968 | vmf->orig_pte = ptep_get_lockless(vmf->pte); | |
4969 | vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; | |
4970 | ||
4971 | if (pte_none(vmf->orig_pte)) { | |
4972 | pte_unmap(vmf->pte); | |
4973 | vmf->pte = NULL; | |
4974 | } | |
4975 | } | |
4976 | ||
4977 | if (!vmf->pte) | |
4978 | return do_pte_missing(vmf); | |
4979 | ||
4980 | if (!pte_present(vmf->orig_pte)) | |
4981 | return do_swap_page(vmf); | |
4982 | ||
4983 | if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) | |
4984 | return do_numa_page(vmf); | |
4985 | ||
4986 | spin_lock(vmf->ptl); | |
4987 | entry = vmf->orig_pte; | |
4988 | if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) { | |
4989 | update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); | |
4990 | goto unlock; | |
4991 | } | |
4992 | if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { | |
4993 | if (!pte_write(entry)) | |
4994 | return do_wp_page(vmf); | |
4995 | else if (likely(vmf->flags & FAULT_FLAG_WRITE)) | |
4996 | entry = pte_mkdirty(entry); | |
4997 | } | |
4998 | entry = pte_mkyoung(entry); | |
4999 | if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, | |
5000 | vmf->flags & FAULT_FLAG_WRITE)) { | |
5001 | update_mmu_cache_range(vmf, vmf->vma, vmf->address, | |
5002 | vmf->pte, 1); | |
5003 | } else { | |
5004 | /* Skip spurious TLB flush for retried page fault */ | |
5005 | if (vmf->flags & FAULT_FLAG_TRIED) | |
5006 | goto unlock; | |
5007 | /* | |
5008 | * This is needed only for protection faults but the arch code | |
5009 | * is not yet telling us if this is a protection fault or not. | |
5010 | * This still avoids useless tlb flushes for .text page faults | |
5011 | * with threads. | |
5012 | */ | |
5013 | if (vmf->flags & FAULT_FLAG_WRITE) | |
5014 | flush_tlb_fix_spurious_fault(vmf->vma, vmf->address, | |
5015 | vmf->pte); | |
5016 | } | |
5017 | unlock: | |
5018 | pte_unmap_unlock(vmf->pte, vmf->ptl); | |
5019 | return 0; | |
5020 | } | |
5021 | ||
5022 | /* | |
5023 | * On entry, we hold either the VMA lock or the mmap_lock | |
5024 | * (FAULT_FLAG_VMA_LOCK tells you which). If VM_FAULT_RETRY is set in | |
5025 | * the result, the mmap_lock is not held on exit. See filemap_fault() | |
5026 | * and __folio_lock_or_retry(). | |
5027 | */ | |
5028 | static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, | |
5029 | unsigned long address, unsigned int flags) | |
5030 | { | |
5031 | struct vm_fault vmf = { | |
5032 | .vma = vma, | |
5033 | .address = address & PAGE_MASK, | |
5034 | .real_address = address, | |
5035 | .flags = flags, | |
5036 | .pgoff = linear_page_index(vma, address), | |
5037 | .gfp_mask = __get_fault_gfp_mask(vma), | |
5038 | }; | |
5039 | struct mm_struct *mm = vma->vm_mm; | |
5040 | unsigned long vm_flags = vma->vm_flags; | |
5041 | pgd_t *pgd; | |
5042 | p4d_t *p4d; | |
5043 | vm_fault_t ret; | |
5044 | ||
5045 | pgd = pgd_offset(mm, address); | |
5046 | p4d = p4d_alloc(mm, pgd, address); | |
5047 | if (!p4d) | |
5048 | return VM_FAULT_OOM; | |
5049 | ||
5050 | vmf.pud = pud_alloc(mm, p4d, address); | |
5051 | if (!vmf.pud) | |
5052 | return VM_FAULT_OOM; | |
5053 | retry_pud: | |
5054 | if (pud_none(*vmf.pud) && | |
5055 | hugepage_vma_check(vma, vm_flags, false, true, true)) { | |
5056 | ret = create_huge_pud(&vmf); | |
5057 | if (!(ret & VM_FAULT_FALLBACK)) | |
5058 | return ret; | |
5059 | } else { | |
5060 | pud_t orig_pud = *vmf.pud; | |
5061 | ||
5062 | barrier(); | |
5063 | if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { | |
5064 | ||
5065 | /* | |
5066 | * TODO once we support anonymous PUDs: NUMA case and | |
5067 | * FAULT_FLAG_UNSHARE handling. | |
5068 | */ | |
5069 | if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) { | |
5070 | ret = wp_huge_pud(&vmf, orig_pud); | |
5071 | if (!(ret & VM_FAULT_FALLBACK)) | |
5072 | return ret; | |
5073 | } else { | |
5074 | huge_pud_set_accessed(&vmf, orig_pud); | |
5075 | return 0; | |
5076 | } | |
5077 | } | |
5078 | } | |
5079 | ||
5080 | vmf.pmd = pmd_alloc(mm, vmf.pud, address); | |
5081 | if (!vmf.pmd) | |
5082 | return VM_FAULT_OOM; | |
5083 | ||
5084 | /* Huge pud page fault raced with pmd_alloc? */ | |
5085 | if (pud_trans_unstable(vmf.pud)) | |
5086 | goto retry_pud; | |
5087 | ||
5088 | if (pmd_none(*vmf.pmd) && | |
5089 | hugepage_vma_check(vma, vm_flags, false, true, true)) { | |
5090 | ret = create_huge_pmd(&vmf); | |
5091 | if (!(ret & VM_FAULT_FALLBACK)) | |
5092 | return ret; | |
5093 | } else { | |
5094 | vmf.orig_pmd = pmdp_get_lockless(vmf.pmd); | |
5095 | ||
5096 | if (unlikely(is_swap_pmd(vmf.orig_pmd))) { | |
5097 | VM_BUG_ON(thp_migration_supported() && | |
5098 | !is_pmd_migration_entry(vmf.orig_pmd)); | |
5099 | if (is_pmd_migration_entry(vmf.orig_pmd)) | |
5100 | pmd_migration_entry_wait(mm, vmf.pmd); | |
5101 | return 0; | |
5102 | } | |
5103 | if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) { | |
5104 | if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma)) | |
5105 | return do_huge_pmd_numa_page(&vmf); | |
5106 | ||
5107 | if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) && | |
5108 | !pmd_write(vmf.orig_pmd)) { | |
5109 | ret = wp_huge_pmd(&vmf); | |
5110 | if (!(ret & VM_FAULT_FALLBACK)) | |
5111 | return ret; | |
5112 | } else { | |
5113 | huge_pmd_set_accessed(&vmf); | |
5114 | return 0; | |
5115 | } | |
5116 | } | |
5117 | } | |
5118 | ||
5119 | return handle_pte_fault(&vmf); | |
5120 | } | |
5121 | ||
5122 | /** | |
5123 | * mm_account_fault - Do page fault accounting | |
5124 | * @mm: mm from which memcg should be extracted. It can be NULL. | |
5125 | * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting | |
5126 | * of perf event counters, but we'll still do the per-task accounting to | |
5127 | * the task who triggered this page fault. | |
5128 | * @address: the faulted address. | |
5129 | * @flags: the fault flags. | |
5130 | * @ret: the fault retcode. | |
5131 | * | |
5132 | * This will take care of most of the page fault accounting. Meanwhile, it | |
5133 | * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter | |
5134 | * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should | |
5135 | * still be in per-arch page fault handlers at the entry of page fault. | |
5136 | */ | |
5137 | static inline void mm_account_fault(struct mm_struct *mm, struct pt_regs *regs, | |
5138 | unsigned long address, unsigned int flags, | |
5139 | vm_fault_t ret) | |
5140 | { | |
5141 | bool major; | |
5142 | ||
5143 | /* Incomplete faults will be accounted upon completion. */ | |
5144 | if (ret & VM_FAULT_RETRY) | |
5145 | return; | |
5146 | ||
5147 | /* | |
5148 | * To preserve the behavior of older kernels, PGFAULT counters record | |
5149 | * both successful and failed faults, as opposed to perf counters, | |
5150 | * which ignore failed cases. | |
5151 | */ | |
5152 | count_vm_event(PGFAULT); | |
5153 | count_memcg_event_mm(mm, PGFAULT); | |
5154 | ||
5155 | /* | |
5156 | * Do not account for unsuccessful faults (e.g. when the address wasn't | |
5157 | * valid). That includes arch_vma_access_permitted() failing before | |
5158 | * reaching here. So this is not a "this many hardware page faults" | |
5159 | * counter. We should use the hw profiling for that. | |
5160 | */ | |
5161 | if (ret & VM_FAULT_ERROR) | |
5162 | return; | |
5163 | ||
5164 | /* | |
5165 | * We define the fault as a major fault when the final successful fault | |
5166 | * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't | |
5167 | * handle it immediately previously). | |
5168 | */ | |
5169 | major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED); | |
5170 | ||
5171 | if (major) | |
5172 | current->maj_flt++; | |
5173 | else | |
5174 | current->min_flt++; | |
5175 | ||
5176 | /* | |
5177 | * If the fault is done for GUP, regs will be NULL. We only do the | |
5178 | * accounting for the per thread fault counters who triggered the | |
5179 | * fault, and we skip the perf event updates. | |
5180 | */ | |
5181 | if (!regs) | |
5182 | return; | |
5183 | ||
5184 | if (major) | |
5185 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); | |
5186 | else | |
5187 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); | |
5188 | } | |
5189 | ||
5190 | #ifdef CONFIG_LRU_GEN | |
5191 | static void lru_gen_enter_fault(struct vm_area_struct *vma) | |
5192 | { | |
5193 | /* the LRU algorithm only applies to accesses with recency */ | |
5194 | current->in_lru_fault = vma_has_recency(vma); | |
5195 | } | |
5196 | ||
5197 | static void lru_gen_exit_fault(void) | |
5198 | { | |
5199 | current->in_lru_fault = false; | |
5200 | } | |
5201 | #else | |
5202 | static void lru_gen_enter_fault(struct vm_area_struct *vma) | |
5203 | { | |
5204 | } | |
5205 | ||
5206 | static void lru_gen_exit_fault(void) | |
5207 | { | |
5208 | } | |
5209 | #endif /* CONFIG_LRU_GEN */ | |
5210 | ||
5211 | static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma, | |
5212 | unsigned int *flags) | |
5213 | { | |
5214 | if (unlikely(*flags & FAULT_FLAG_UNSHARE)) { | |
5215 | if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE)) | |
5216 | return VM_FAULT_SIGSEGV; | |
5217 | /* | |
5218 | * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's | |
5219 | * just treat it like an ordinary read-fault otherwise. | |
5220 | */ | |
5221 | if (!is_cow_mapping(vma->vm_flags)) | |
5222 | *flags &= ~FAULT_FLAG_UNSHARE; | |
5223 | } else if (*flags & FAULT_FLAG_WRITE) { | |
5224 | /* Write faults on read-only mappings are impossible ... */ | |
5225 | if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE))) | |
5226 | return VM_FAULT_SIGSEGV; | |
5227 | /* ... and FOLL_FORCE only applies to COW mappings. */ | |
5228 | if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) && | |
5229 | !is_cow_mapping(vma->vm_flags))) | |
5230 | return VM_FAULT_SIGSEGV; | |
5231 | } | |
5232 | #ifdef CONFIG_PER_VMA_LOCK | |
5233 | /* | |
5234 | * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of | |
5235 | * the assumption that lock is dropped on VM_FAULT_RETRY. | |
5236 | */ | |
5237 | if (WARN_ON_ONCE((*flags & | |
5238 | (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) == | |
5239 | (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT))) | |
5240 | return VM_FAULT_SIGSEGV; | |
5241 | #endif | |
5242 | ||
5243 | return 0; | |
5244 | } | |
5245 | ||
5246 | /* | |
5247 | * By the time we get here, we already hold the mm semaphore | |
5248 | * | |
5249 | * The mmap_lock may have been released depending on flags and our | |
5250 | * return value. See filemap_fault() and __folio_lock_or_retry(). | |
5251 | */ | |
5252 | vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, | |
5253 | unsigned int flags, struct pt_regs *regs) | |
5254 | { | |
5255 | /* If the fault handler drops the mmap_lock, vma may be freed */ | |
5256 | struct mm_struct *mm = vma->vm_mm; | |
5257 | vm_fault_t ret; | |
5258 | ||
5259 | __set_current_state(TASK_RUNNING); | |
5260 | ||
5261 | ret = sanitize_fault_flags(vma, &flags); | |
5262 | if (ret) | |
5263 | goto out; | |
5264 | ||
5265 | if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, | |
5266 | flags & FAULT_FLAG_INSTRUCTION, | |
5267 | flags & FAULT_FLAG_REMOTE)) { | |
5268 | ret = VM_FAULT_SIGSEGV; | |
5269 | goto out; | |
5270 | } | |
5271 | ||
5272 | /* | |
5273 | * Enable the memcg OOM handling for faults triggered in user | |
5274 | * space. Kernel faults are handled more gracefully. | |
5275 | */ | |
5276 | if (flags & FAULT_FLAG_USER) | |
5277 | mem_cgroup_enter_user_fault(); | |
5278 | ||
5279 | lru_gen_enter_fault(vma); | |
5280 | ||
5281 | if (unlikely(is_vm_hugetlb_page(vma))) | |
5282 | ret = hugetlb_fault(vma->vm_mm, vma, address, flags); | |
5283 | else | |
5284 | ret = __handle_mm_fault(vma, address, flags); | |
5285 | ||
5286 | lru_gen_exit_fault(); | |
5287 | ||
5288 | if (flags & FAULT_FLAG_USER) { | |
5289 | mem_cgroup_exit_user_fault(); | |
5290 | /* | |
5291 | * The task may have entered a memcg OOM situation but | |
5292 | * if the allocation error was handled gracefully (no | |
5293 | * VM_FAULT_OOM), there is no need to kill anything. | |
5294 | * Just clean up the OOM state peacefully. | |
5295 | */ | |
5296 | if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) | |
5297 | mem_cgroup_oom_synchronize(false); | |
5298 | } | |
5299 | out: | |
5300 | mm_account_fault(mm, regs, address, flags, ret); | |
5301 | ||
5302 | return ret; | |
5303 | } | |
5304 | EXPORT_SYMBOL_GPL(handle_mm_fault); | |
5305 | ||
5306 | #ifdef CONFIG_LOCK_MM_AND_FIND_VMA | |
5307 | #include <linux/extable.h> | |
5308 | ||
5309 | static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs) | |
5310 | { | |
5311 | if (likely(mmap_read_trylock(mm))) | |
5312 | return true; | |
5313 | ||
5314 | if (regs && !user_mode(regs)) { | |
5315 | unsigned long ip = instruction_pointer(regs); | |
5316 | if (!search_exception_tables(ip)) | |
5317 | return false; | |
5318 | } | |
5319 | ||
5320 | return !mmap_read_lock_killable(mm); | |
5321 | } | |
5322 | ||
5323 | static inline bool mmap_upgrade_trylock(struct mm_struct *mm) | |
5324 | { | |
5325 | /* | |
5326 | * We don't have this operation yet. | |
5327 | * | |
5328 | * It should be easy enough to do: it's basically a | |
5329 | * atomic_long_try_cmpxchg_acquire() | |
5330 | * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but | |
5331 | * it also needs the proper lockdep magic etc. | |
5332 | */ | |
5333 | return false; | |
5334 | } | |
5335 | ||
5336 | static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs) | |
5337 | { | |
5338 | mmap_read_unlock(mm); | |
5339 | if (regs && !user_mode(regs)) { | |
5340 | unsigned long ip = instruction_pointer(regs); | |
5341 | if (!search_exception_tables(ip)) | |
5342 | return false; | |
5343 | } | |
5344 | return !mmap_write_lock_killable(mm); | |
5345 | } | |
5346 | ||
5347 | /* | |
5348 | * Helper for page fault handling. | |
5349 | * | |
5350 | * This is kind of equivalend to "mmap_read_lock()" followed | |
5351 | * by "find_extend_vma()", except it's a lot more careful about | |
5352 | * the locking (and will drop the lock on failure). | |
5353 | * | |
5354 | * For example, if we have a kernel bug that causes a page | |
5355 | * fault, we don't want to just use mmap_read_lock() to get | |
5356 | * the mm lock, because that would deadlock if the bug were | |
5357 | * to happen while we're holding the mm lock for writing. | |
5358 | * | |
5359 | * So this checks the exception tables on kernel faults in | |
5360 | * order to only do this all for instructions that are actually | |
5361 | * expected to fault. | |
5362 | * | |
5363 | * We can also actually take the mm lock for writing if we | |
5364 | * need to extend the vma, which helps the VM layer a lot. | |
5365 | */ | |
5366 | struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, | |
5367 | unsigned long addr, struct pt_regs *regs) | |
5368 | { | |
5369 | struct vm_area_struct *vma; | |
5370 | ||
5371 | if (!get_mmap_lock_carefully(mm, regs)) | |
5372 | return NULL; | |
5373 | ||
5374 | vma = find_vma(mm, addr); | |
5375 | if (likely(vma && (vma->vm_start <= addr))) | |
5376 | return vma; | |
5377 | ||
5378 | /* | |
5379 | * Well, dang. We might still be successful, but only | |
5380 | * if we can extend a vma to do so. | |
5381 | */ | |
5382 | if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) { | |
5383 | mmap_read_unlock(mm); | |
5384 | return NULL; | |
5385 | } | |
5386 | ||
5387 | /* | |
5388 | * We can try to upgrade the mmap lock atomically, | |
5389 | * in which case we can continue to use the vma | |
5390 | * we already looked up. | |
5391 | * | |
5392 | * Otherwise we'll have to drop the mmap lock and | |
5393 | * re-take it, and also look up the vma again, | |
5394 | * re-checking it. | |
5395 | */ | |
5396 | if (!mmap_upgrade_trylock(mm)) { | |
5397 | if (!upgrade_mmap_lock_carefully(mm, regs)) | |
5398 | return NULL; | |
5399 | ||
5400 | vma = find_vma(mm, addr); | |
5401 | if (!vma) | |
5402 | goto fail; | |
5403 | if (vma->vm_start <= addr) | |
5404 | goto success; | |
5405 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
5406 | goto fail; | |
5407 | } | |
5408 | ||
5409 | if (expand_stack_locked(vma, addr)) | |
5410 | goto fail; | |
5411 | ||
5412 | success: | |
5413 | mmap_write_downgrade(mm); | |
5414 | return vma; | |
5415 | ||
5416 | fail: | |
5417 | mmap_write_unlock(mm); | |
5418 | return NULL; | |
5419 | } | |
5420 | #endif | |
5421 | ||
5422 | #ifdef CONFIG_PER_VMA_LOCK | |
5423 | /* | |
5424 | * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be | |
5425 | * stable and not isolated. If the VMA is not found or is being modified the | |
5426 | * function returns NULL. | |
5427 | */ | |
5428 | struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, | |
5429 | unsigned long address) | |
5430 | { | |
5431 | MA_STATE(mas, &mm->mm_mt, address, address); | |
5432 | struct vm_area_struct *vma; | |
5433 | ||
5434 | rcu_read_lock(); | |
5435 | retry: | |
5436 | vma = mas_walk(&mas); | |
5437 | if (!vma) | |
5438 | goto inval; | |
5439 | ||
5440 | if (!vma_start_read(vma)) | |
5441 | goto inval; | |
5442 | ||
5443 | /* | |
5444 | * find_mergeable_anon_vma uses adjacent vmas which are not locked. | |
5445 | * This check must happen after vma_start_read(); otherwise, a | |
5446 | * concurrent mremap() with MREMAP_DONTUNMAP could dissociate the VMA | |
5447 | * from its anon_vma. | |
5448 | */ | |
5449 | if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) | |
5450 | goto inval_end_read; | |
5451 | ||
5452 | /* Check since vm_start/vm_end might change before we lock the VMA */ | |
5453 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) | |
5454 | goto inval_end_read; | |
5455 | ||
5456 | /* Check if the VMA got isolated after we found it */ | |
5457 | if (vma->detached) { | |
5458 | vma_end_read(vma); | |
5459 | count_vm_vma_lock_event(VMA_LOCK_MISS); | |
5460 | /* The area was replaced with another one */ | |
5461 | goto retry; | |
5462 | } | |
5463 | ||
5464 | rcu_read_unlock(); | |
5465 | return vma; | |
5466 | ||
5467 | inval_end_read: | |
5468 | vma_end_read(vma); | |
5469 | inval: | |
5470 | rcu_read_unlock(); | |
5471 | count_vm_vma_lock_event(VMA_LOCK_ABORT); | |
5472 | return NULL; | |
5473 | } | |
5474 | #endif /* CONFIG_PER_VMA_LOCK */ | |
5475 | ||
5476 | #ifndef __PAGETABLE_P4D_FOLDED | |
5477 | /* | |
5478 | * Allocate p4d page table. | |
5479 | * We've already handled the fast-path in-line. | |
5480 | */ | |
5481 | int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) | |
5482 | { | |
5483 | p4d_t *new = p4d_alloc_one(mm, address); | |
5484 | if (!new) | |
5485 | return -ENOMEM; | |
5486 | ||
5487 | spin_lock(&mm->page_table_lock); | |
5488 | if (pgd_present(*pgd)) { /* Another has populated it */ | |
5489 | p4d_free(mm, new); | |
5490 | } else { | |
5491 | smp_wmb(); /* See comment in pmd_install() */ | |
5492 | pgd_populate(mm, pgd, new); | |
5493 | } | |
5494 | spin_unlock(&mm->page_table_lock); | |
5495 | return 0; | |
5496 | } | |
5497 | #endif /* __PAGETABLE_P4D_FOLDED */ | |
5498 | ||
5499 | #ifndef __PAGETABLE_PUD_FOLDED | |
5500 | /* | |
5501 | * Allocate page upper directory. | |
5502 | * We've already handled the fast-path in-line. | |
5503 | */ | |
5504 | int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) | |
5505 | { | |
5506 | pud_t *new = pud_alloc_one(mm, address); | |
5507 | if (!new) | |
5508 | return -ENOMEM; | |
5509 | ||
5510 | spin_lock(&mm->page_table_lock); | |
5511 | if (!p4d_present(*p4d)) { | |
5512 | mm_inc_nr_puds(mm); | |
5513 | smp_wmb(); /* See comment in pmd_install() */ | |
5514 | p4d_populate(mm, p4d, new); | |
5515 | } else /* Another has populated it */ | |
5516 | pud_free(mm, new); | |
5517 | spin_unlock(&mm->page_table_lock); | |
5518 | return 0; | |
5519 | } | |
5520 | #endif /* __PAGETABLE_PUD_FOLDED */ | |
5521 | ||
5522 | #ifndef __PAGETABLE_PMD_FOLDED | |
5523 | /* | |
5524 | * Allocate page middle directory. | |
5525 | * We've already handled the fast-path in-line. | |
5526 | */ | |
5527 | int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) | |
5528 | { | |
5529 | spinlock_t *ptl; | |
5530 | pmd_t *new = pmd_alloc_one(mm, address); | |
5531 | if (!new) | |
5532 | return -ENOMEM; | |
5533 | ||
5534 | ptl = pud_lock(mm, pud); | |
5535 | if (!pud_present(*pud)) { | |
5536 | mm_inc_nr_pmds(mm); | |
5537 | smp_wmb(); /* See comment in pmd_install() */ | |
5538 | pud_populate(mm, pud, new); | |
5539 | } else { /* Another has populated it */ | |
5540 | pmd_free(mm, new); | |
5541 | } | |
5542 | spin_unlock(ptl); | |
5543 | return 0; | |
5544 | } | |
5545 | #endif /* __PAGETABLE_PMD_FOLDED */ | |
5546 | ||
5547 | /** | |
5548 | * follow_pte - look up PTE at a user virtual address | |
5549 | * @mm: the mm_struct of the target address space | |
5550 | * @address: user virtual address | |
5551 | * @ptepp: location to store found PTE | |
5552 | * @ptlp: location to store the lock for the PTE | |
5553 | * | |
5554 | * On a successful return, the pointer to the PTE is stored in @ptepp; | |
5555 | * the corresponding lock is taken and its location is stored in @ptlp. | |
5556 | * The contents of the PTE are only stable until @ptlp is released; | |
5557 | * any further use, if any, must be protected against invalidation | |
5558 | * with MMU notifiers. | |
5559 | * | |
5560 | * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore | |
5561 | * should be taken for read. | |
5562 | * | |
5563 | * KVM uses this function. While it is arguably less bad than ``follow_pfn``, | |
5564 | * it is not a good general-purpose API. | |
5565 | * | |
5566 | * Return: zero on success, -ve otherwise. | |
5567 | */ | |
5568 | int follow_pte(struct mm_struct *mm, unsigned long address, | |
5569 | pte_t **ptepp, spinlock_t **ptlp) | |
5570 | { | |
5571 | pgd_t *pgd; | |
5572 | p4d_t *p4d; | |
5573 | pud_t *pud; | |
5574 | pmd_t *pmd; | |
5575 | pte_t *ptep; | |
5576 | ||
5577 | pgd = pgd_offset(mm, address); | |
5578 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) | |
5579 | goto out; | |
5580 | ||
5581 | p4d = p4d_offset(pgd, address); | |
5582 | if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d))) | |
5583 | goto out; | |
5584 | ||
5585 | pud = pud_offset(p4d, address); | |
5586 | if (pud_none(*pud) || unlikely(pud_bad(*pud))) | |
5587 | goto out; | |
5588 | ||
5589 | pmd = pmd_offset(pud, address); | |
5590 | VM_BUG_ON(pmd_trans_huge(*pmd)); | |
5591 | ||
5592 | ptep = pte_offset_map_lock(mm, pmd, address, ptlp); | |
5593 | if (!ptep) | |
5594 | goto out; | |
5595 | if (!pte_present(ptep_get(ptep))) | |
5596 | goto unlock; | |
5597 | *ptepp = ptep; | |
5598 | return 0; | |
5599 | unlock: | |
5600 | pte_unmap_unlock(ptep, *ptlp); | |
5601 | out: | |
5602 | return -EINVAL; | |
5603 | } | |
5604 | EXPORT_SYMBOL_GPL(follow_pte); | |
5605 | ||
5606 | /** | |
5607 | * follow_pfn - look up PFN at a user virtual address | |
5608 | * @vma: memory mapping | |
5609 | * @address: user virtual address | |
5610 | * @pfn: location to store found PFN | |
5611 | * | |
5612 | * Only IO mappings and raw PFN mappings are allowed. | |
5613 | * | |
5614 | * This function does not allow the caller to read the permissions | |
5615 | * of the PTE. Do not use it. | |
5616 | * | |
5617 | * Return: zero and the pfn at @pfn on success, -ve otherwise. | |
5618 | */ | |
5619 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, | |
5620 | unsigned long *pfn) | |
5621 | { | |
5622 | int ret = -EINVAL; | |
5623 | spinlock_t *ptl; | |
5624 | pte_t *ptep; | |
5625 | ||
5626 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) | |
5627 | return ret; | |
5628 | ||
5629 | ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); | |
5630 | if (ret) | |
5631 | return ret; | |
5632 | *pfn = pte_pfn(ptep_get(ptep)); | |
5633 | pte_unmap_unlock(ptep, ptl); | |
5634 | return 0; | |
5635 | } | |
5636 | EXPORT_SYMBOL(follow_pfn); | |
5637 | ||
5638 | #ifdef CONFIG_HAVE_IOREMAP_PROT | |
5639 | int follow_phys(struct vm_area_struct *vma, | |
5640 | unsigned long address, unsigned int flags, | |
5641 | unsigned long *prot, resource_size_t *phys) | |
5642 | { | |
5643 | int ret = -EINVAL; | |
5644 | pte_t *ptep, pte; | |
5645 | spinlock_t *ptl; | |
5646 | ||
5647 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) | |
5648 | goto out; | |
5649 | ||
5650 | if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) | |
5651 | goto out; | |
5652 | pte = ptep_get(ptep); | |
5653 | ||
5654 | if ((flags & FOLL_WRITE) && !pte_write(pte)) | |
5655 | goto unlock; | |
5656 | ||
5657 | *prot = pgprot_val(pte_pgprot(pte)); | |
5658 | *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; | |
5659 | ||
5660 | ret = 0; | |
5661 | unlock: | |
5662 | pte_unmap_unlock(ptep, ptl); | |
5663 | out: | |
5664 | return ret; | |
5665 | } | |
5666 | ||
5667 | /** | |
5668 | * generic_access_phys - generic implementation for iomem mmap access | |
5669 | * @vma: the vma to access | |
5670 | * @addr: userspace address, not relative offset within @vma | |
5671 | * @buf: buffer to read/write | |
5672 | * @len: length of transfer | |
5673 | * @write: set to FOLL_WRITE when writing, otherwise reading | |
5674 | * | |
5675 | * This is a generic implementation for &vm_operations_struct.access for an | |
5676 | * iomem mapping. This callback is used by access_process_vm() when the @vma is | |
5677 | * not page based. | |
5678 | */ | |
5679 | int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, | |
5680 | void *buf, int len, int write) | |
5681 | { | |
5682 | resource_size_t phys_addr; | |
5683 | unsigned long prot = 0; | |
5684 | void __iomem *maddr; | |
5685 | pte_t *ptep, pte; | |
5686 | spinlock_t *ptl; | |
5687 | int offset = offset_in_page(addr); | |
5688 | int ret = -EINVAL; | |
5689 | ||
5690 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) | |
5691 | return -EINVAL; | |
5692 | ||
5693 | retry: | |
5694 | if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) | |
5695 | return -EINVAL; | |
5696 | pte = ptep_get(ptep); | |
5697 | pte_unmap_unlock(ptep, ptl); | |
5698 | ||
5699 | prot = pgprot_val(pte_pgprot(pte)); | |
5700 | phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; | |
5701 | ||
5702 | if ((write & FOLL_WRITE) && !pte_write(pte)) | |
5703 | return -EINVAL; | |
5704 | ||
5705 | maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); | |
5706 | if (!maddr) | |
5707 | return -ENOMEM; | |
5708 | ||
5709 | if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) | |
5710 | goto out_unmap; | |
5711 | ||
5712 | if (!pte_same(pte, ptep_get(ptep))) { | |
5713 | pte_unmap_unlock(ptep, ptl); | |
5714 | iounmap(maddr); | |
5715 | ||
5716 | goto retry; | |
5717 | } | |
5718 | ||
5719 | if (write) | |
5720 | memcpy_toio(maddr + offset, buf, len); | |
5721 | else | |
5722 | memcpy_fromio(buf, maddr + offset, len); | |
5723 | ret = len; | |
5724 | pte_unmap_unlock(ptep, ptl); | |
5725 | out_unmap: | |
5726 | iounmap(maddr); | |
5727 | ||
5728 | return ret; | |
5729 | } | |
5730 | EXPORT_SYMBOL_GPL(generic_access_phys); | |
5731 | #endif | |
5732 | ||
5733 | /* | |
5734 | * Access another process' address space as given in mm. | |
5735 | */ | |
5736 | int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, | |
5737 | int len, unsigned int gup_flags) | |
5738 | { | |
5739 | void *old_buf = buf; | |
5740 | int write = gup_flags & FOLL_WRITE; | |
5741 | ||
5742 | if (mmap_read_lock_killable(mm)) | |
5743 | return 0; | |
5744 | ||
5745 | /* Untag the address before looking up the VMA */ | |
5746 | addr = untagged_addr_remote(mm, addr); | |
5747 | ||
5748 | /* Avoid triggering the temporary warning in __get_user_pages */ | |
5749 | if (!vma_lookup(mm, addr) && !expand_stack(mm, addr)) | |
5750 | return 0; | |
5751 | ||
5752 | /* ignore errors, just check how much was successfully transferred */ | |
5753 | while (len) { | |
5754 | int bytes, offset; | |
5755 | void *maddr; | |
5756 | struct vm_area_struct *vma = NULL; | |
5757 | struct page *page = get_user_page_vma_remote(mm, addr, | |
5758 | gup_flags, &vma); | |
5759 | ||
5760 | if (IS_ERR_OR_NULL(page)) { | |
5761 | /* We might need to expand the stack to access it */ | |
5762 | vma = vma_lookup(mm, addr); | |
5763 | if (!vma) { | |
5764 | vma = expand_stack(mm, addr); | |
5765 | ||
5766 | /* mmap_lock was dropped on failure */ | |
5767 | if (!vma) | |
5768 | return buf - old_buf; | |
5769 | ||
5770 | /* Try again if stack expansion worked */ | |
5771 | continue; | |
5772 | } | |
5773 | ||
5774 | ||
5775 | /* | |
5776 | * Check if this is a VM_IO | VM_PFNMAP VMA, which | |
5777 | * we can access using slightly different code. | |
5778 | */ | |
5779 | bytes = 0; | |
5780 | #ifdef CONFIG_HAVE_IOREMAP_PROT | |
5781 | if (vma->vm_ops && vma->vm_ops->access) | |
5782 | bytes = vma->vm_ops->access(vma, addr, buf, | |
5783 | len, write); | |
5784 | #endif | |
5785 | if (bytes <= 0) | |
5786 | break; | |
5787 | } else { | |
5788 | bytes = len; | |
5789 | offset = addr & (PAGE_SIZE-1); | |
5790 | if (bytes > PAGE_SIZE-offset) | |
5791 | bytes = PAGE_SIZE-offset; | |
5792 | ||
5793 | maddr = kmap(page); | |
5794 | if (write) { | |
5795 | copy_to_user_page(vma, page, addr, | |
5796 | maddr + offset, buf, bytes); | |
5797 | set_page_dirty_lock(page); | |
5798 | } else { | |
5799 | copy_from_user_page(vma, page, addr, | |
5800 | buf, maddr + offset, bytes); | |
5801 | } | |
5802 | kunmap(page); | |
5803 | put_page(page); | |
5804 | } | |
5805 | len -= bytes; | |
5806 | buf += bytes; | |
5807 | addr += bytes; | |
5808 | } | |
5809 | mmap_read_unlock(mm); | |
5810 | ||
5811 | return buf - old_buf; | |
5812 | } | |
5813 | ||
5814 | /** | |
5815 | * access_remote_vm - access another process' address space | |
5816 | * @mm: the mm_struct of the target address space | |
5817 | * @addr: start address to access | |
5818 | * @buf: source or destination buffer | |
5819 | * @len: number of bytes to transfer | |
5820 | * @gup_flags: flags modifying lookup behaviour | |
5821 | * | |
5822 | * The caller must hold a reference on @mm. | |
5823 | * | |
5824 | * Return: number of bytes copied from source to destination. | |
5825 | */ | |
5826 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, | |
5827 | void *buf, int len, unsigned int gup_flags) | |
5828 | { | |
5829 | return __access_remote_vm(mm, addr, buf, len, gup_flags); | |
5830 | } | |
5831 | ||
5832 | /* | |
5833 | * Access another process' address space. | |
5834 | * Source/target buffer must be kernel space, | |
5835 | * Do not walk the page table directly, use get_user_pages | |
5836 | */ | |
5837 | int access_process_vm(struct task_struct *tsk, unsigned long addr, | |
5838 | void *buf, int len, unsigned int gup_flags) | |
5839 | { | |
5840 | struct mm_struct *mm; | |
5841 | int ret; | |
5842 | ||
5843 | mm = get_task_mm(tsk); | |
5844 | if (!mm) | |
5845 | return 0; | |
5846 | ||
5847 | ret = __access_remote_vm(mm, addr, buf, len, gup_flags); | |
5848 | ||
5849 | mmput(mm); | |
5850 | ||
5851 | return ret; | |
5852 | } | |
5853 | EXPORT_SYMBOL_GPL(access_process_vm); | |
5854 | ||
5855 | /* | |
5856 | * Print the name of a VMA. | |
5857 | */ | |
5858 | void print_vma_addr(char *prefix, unsigned long ip) | |
5859 | { | |
5860 | struct mm_struct *mm = current->mm; | |
5861 | struct vm_area_struct *vma; | |
5862 | ||
5863 | /* | |
5864 | * we might be running from an atomic context so we cannot sleep | |
5865 | */ | |
5866 | if (!mmap_read_trylock(mm)) | |
5867 | return; | |
5868 | ||
5869 | vma = find_vma(mm, ip); | |
5870 | if (vma && vma->vm_file) { | |
5871 | struct file *f = vma->vm_file; | |
5872 | char *buf = (char *)__get_free_page(GFP_NOWAIT); | |
5873 | if (buf) { | |
5874 | char *p; | |
5875 | ||
5876 | p = file_path(f, buf, PAGE_SIZE); | |
5877 | if (IS_ERR(p)) | |
5878 | p = "?"; | |
5879 | printk("%s%s[%lx+%lx]", prefix, kbasename(p), | |
5880 | vma->vm_start, | |
5881 | vma->vm_end - vma->vm_start); | |
5882 | free_page((unsigned long)buf); | |
5883 | } | |
5884 | } | |
5885 | mmap_read_unlock(mm); | |
5886 | } | |
5887 | ||
5888 | #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) | |
5889 | void __might_fault(const char *file, int line) | |
5890 | { | |
5891 | if (pagefault_disabled()) | |
5892 | return; | |
5893 | __might_sleep(file, line); | |
5894 | #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) | |
5895 | if (current->mm) | |
5896 | might_lock_read(¤t->mm->mmap_lock); | |
5897 | #endif | |
5898 | } | |
5899 | EXPORT_SYMBOL(__might_fault); | |
5900 | #endif | |
5901 | ||
5902 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) | |
5903 | /* | |
5904 | * Process all subpages of the specified huge page with the specified | |
5905 | * operation. The target subpage will be processed last to keep its | |
5906 | * cache lines hot. | |
5907 | */ | |
5908 | static inline int process_huge_page( | |
5909 | unsigned long addr_hint, unsigned int pages_per_huge_page, | |
5910 | int (*process_subpage)(unsigned long addr, int idx, void *arg), | |
5911 | void *arg) | |
5912 | { | |
5913 | int i, n, base, l, ret; | |
5914 | unsigned long addr = addr_hint & | |
5915 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); | |
5916 | ||
5917 | /* Process target subpage last to keep its cache lines hot */ | |
5918 | might_sleep(); | |
5919 | n = (addr_hint - addr) / PAGE_SIZE; | |
5920 | if (2 * n <= pages_per_huge_page) { | |
5921 | /* If target subpage in first half of huge page */ | |
5922 | base = 0; | |
5923 | l = n; | |
5924 | /* Process subpages at the end of huge page */ | |
5925 | for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { | |
5926 | cond_resched(); | |
5927 | ret = process_subpage(addr + i * PAGE_SIZE, i, arg); | |
5928 | if (ret) | |
5929 | return ret; | |
5930 | } | |
5931 | } else { | |
5932 | /* If target subpage in second half of huge page */ | |
5933 | base = pages_per_huge_page - 2 * (pages_per_huge_page - n); | |
5934 | l = pages_per_huge_page - n; | |
5935 | /* Process subpages at the begin of huge page */ | |
5936 | for (i = 0; i < base; i++) { | |
5937 | cond_resched(); | |
5938 | ret = process_subpage(addr + i * PAGE_SIZE, i, arg); | |
5939 | if (ret) | |
5940 | return ret; | |
5941 | } | |
5942 | } | |
5943 | /* | |
5944 | * Process remaining subpages in left-right-left-right pattern | |
5945 | * towards the target subpage | |
5946 | */ | |
5947 | for (i = 0; i < l; i++) { | |
5948 | int left_idx = base + i; | |
5949 | int right_idx = base + 2 * l - 1 - i; | |
5950 | ||
5951 | cond_resched(); | |
5952 | ret = process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg); | |
5953 | if (ret) | |
5954 | return ret; | |
5955 | cond_resched(); | |
5956 | ret = process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg); | |
5957 | if (ret) | |
5958 | return ret; | |
5959 | } | |
5960 | return 0; | |
5961 | } | |
5962 | ||
5963 | static void clear_gigantic_page(struct page *page, | |
5964 | unsigned long addr, | |
5965 | unsigned int pages_per_huge_page) | |
5966 | { | |
5967 | int i; | |
5968 | struct page *p; | |
5969 | ||
5970 | might_sleep(); | |
5971 | for (i = 0; i < pages_per_huge_page; i++) { | |
5972 | p = nth_page(page, i); | |
5973 | cond_resched(); | |
5974 | clear_user_highpage(p, addr + i * PAGE_SIZE); | |
5975 | } | |
5976 | } | |
5977 | ||
5978 | static int clear_subpage(unsigned long addr, int idx, void *arg) | |
5979 | { | |
5980 | struct page *page = arg; | |
5981 | ||
5982 | clear_user_highpage(page + idx, addr); | |
5983 | return 0; | |
5984 | } | |
5985 | ||
5986 | void clear_huge_page(struct page *page, | |
5987 | unsigned long addr_hint, unsigned int pages_per_huge_page) | |
5988 | { | |
5989 | unsigned long addr = addr_hint & | |
5990 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); | |
5991 | ||
5992 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { | |
5993 | clear_gigantic_page(page, addr, pages_per_huge_page); | |
5994 | return; | |
5995 | } | |
5996 | ||
5997 | process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page); | |
5998 | } | |
5999 | ||
6000 | static int copy_user_gigantic_page(struct folio *dst, struct folio *src, | |
6001 | unsigned long addr, | |
6002 | struct vm_area_struct *vma, | |
6003 | unsigned int pages_per_huge_page) | |
6004 | { | |
6005 | int i; | |
6006 | struct page *dst_page; | |
6007 | struct page *src_page; | |
6008 | ||
6009 | for (i = 0; i < pages_per_huge_page; i++) { | |
6010 | dst_page = folio_page(dst, i); | |
6011 | src_page = folio_page(src, i); | |
6012 | ||
6013 | cond_resched(); | |
6014 | if (copy_mc_user_highpage(dst_page, src_page, | |
6015 | addr + i*PAGE_SIZE, vma)) { | |
6016 | memory_failure_queue(page_to_pfn(src_page), 0); | |
6017 | return -EHWPOISON; | |
6018 | } | |
6019 | } | |
6020 | return 0; | |
6021 | } | |
6022 | ||
6023 | struct copy_subpage_arg { | |
6024 | struct page *dst; | |
6025 | struct page *src; | |
6026 | struct vm_area_struct *vma; | |
6027 | }; | |
6028 | ||
6029 | static int copy_subpage(unsigned long addr, int idx, void *arg) | |
6030 | { | |
6031 | struct copy_subpage_arg *copy_arg = arg; | |
6032 | ||
6033 | if (copy_mc_user_highpage(copy_arg->dst + idx, copy_arg->src + idx, | |
6034 | addr, copy_arg->vma)) { | |
6035 | memory_failure_queue(page_to_pfn(copy_arg->src + idx), 0); | |
6036 | return -EHWPOISON; | |
6037 | } | |
6038 | return 0; | |
6039 | } | |
6040 | ||
6041 | int copy_user_large_folio(struct folio *dst, struct folio *src, | |
6042 | unsigned long addr_hint, struct vm_area_struct *vma) | |
6043 | { | |
6044 | unsigned int pages_per_huge_page = folio_nr_pages(dst); | |
6045 | unsigned long addr = addr_hint & | |
6046 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); | |
6047 | struct copy_subpage_arg arg = { | |
6048 | .dst = &dst->page, | |
6049 | .src = &src->page, | |
6050 | .vma = vma, | |
6051 | }; | |
6052 | ||
6053 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) | |
6054 | return copy_user_gigantic_page(dst, src, addr, vma, | |
6055 | pages_per_huge_page); | |
6056 | ||
6057 | return process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg); | |
6058 | } | |
6059 | ||
6060 | long copy_folio_from_user(struct folio *dst_folio, | |
6061 | const void __user *usr_src, | |
6062 | bool allow_pagefault) | |
6063 | { | |
6064 | void *kaddr; | |
6065 | unsigned long i, rc = 0; | |
6066 | unsigned int nr_pages = folio_nr_pages(dst_folio); | |
6067 | unsigned long ret_val = nr_pages * PAGE_SIZE; | |
6068 | struct page *subpage; | |
6069 | ||
6070 | for (i = 0; i < nr_pages; i++) { | |
6071 | subpage = folio_page(dst_folio, i); | |
6072 | kaddr = kmap_local_page(subpage); | |
6073 | if (!allow_pagefault) | |
6074 | pagefault_disable(); | |
6075 | rc = copy_from_user(kaddr, usr_src + i * PAGE_SIZE, PAGE_SIZE); | |
6076 | if (!allow_pagefault) | |
6077 | pagefault_enable(); | |
6078 | kunmap_local(kaddr); | |
6079 | ||
6080 | ret_val -= (PAGE_SIZE - rc); | |
6081 | if (rc) | |
6082 | break; | |
6083 | ||
6084 | flush_dcache_page(subpage); | |
6085 | ||
6086 | cond_resched(); | |
6087 | } | |
6088 | return ret_val; | |
6089 | } | |
6090 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ | |
6091 | ||
6092 | #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS | |
6093 | ||
6094 | static struct kmem_cache *page_ptl_cachep; | |
6095 | ||
6096 | void __init ptlock_cache_init(void) | |
6097 | { | |
6098 | page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, | |
6099 | SLAB_PANIC, NULL); | |
6100 | } | |
6101 | ||
6102 | bool ptlock_alloc(struct ptdesc *ptdesc) | |
6103 | { | |
6104 | spinlock_t *ptl; | |
6105 | ||
6106 | ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); | |
6107 | if (!ptl) | |
6108 | return false; | |
6109 | ptdesc->ptl = ptl; | |
6110 | return true; | |
6111 | } | |
6112 | ||
6113 | void ptlock_free(struct ptdesc *ptdesc) | |
6114 | { | |
6115 | kmem_cache_free(page_ptl_cachep, ptdesc->ptl); | |
6116 | } | |
6117 | #endif |