1 | |
2 | // SPDX-License-Identifier: GPL-2.0-only |
3 | /* |
4 | * linux/mm/memory.c |
5 | * |
6 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
7 | */ |
8 | |
9 | /* |
10 | * demand-loading started 01.12.91 - seems it is high on the list of |
11 | * things wanted, and it should be easy to implement. - Linus |
12 | */ |
13 | |
14 | /* |
15 | * Ok, demand-loading was easy, shared pages a little bit tricker. Shared |
16 | * pages started 02.12.91, seems to work. - Linus. |
17 | * |
18 | * Tested sharing by executing about 30 /bin/sh: under the old kernel it |
19 | * would have taken more than the 6M I have free, but it worked well as |
20 | * far as I could see. |
21 | * |
22 | * Also corrected some "invalidate()"s - I wasn't doing enough of them. |
23 | */ |
24 | |
25 | /* |
26 | * Real VM (paging to/from disk) started 18.12.91. Much more work and |
27 | * thought has to go into this. Oh, well.. |
28 | * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. |
29 | * Found it. Everything seems to work now. |
30 | * 20.12.91 - Ok, making the swap-device changeable like the root. |
31 | */ |
32 | |
33 | /* |
34 | * 05.04.94 - Multi-page memory management added for v1.1. |
35 | * Idea by Alex Bligh (alex@cconcepts.co.uk) |
36 | * |
37 | * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG |
38 | * (Gerhard.Wichert@pdb.siemens.de) |
39 | * |
40 | * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) |
41 | */ |
42 | |
43 | #include <linux/kernel_stat.h> |
44 | #include <linux/mm.h> |
45 | #include <linux/mm_inline.h> |
46 | #include <linux/sched/mm.h> |
47 | #include <linux/sched/coredump.h> |
48 | #include <linux/sched/numa_balancing.h> |
49 | #include <linux/sched/task.h> |
50 | #include <linux/hugetlb.h> |
51 | #include <linux/mman.h> |
52 | #include <linux/swap.h> |
53 | #include <linux/highmem.h> |
54 | #include <linux/pagemap.h> |
55 | #include <linux/memremap.h> |
56 | #include <linux/kmsan.h> |
57 | #include <linux/ksm.h> |
58 | #include <linux/rmap.h> |
59 | #include <linux/export.h> |
60 | #include <linux/delayacct.h> |
61 | #include <linux/init.h> |
62 | #include <linux/pfn_t.h> |
63 | #include <linux/writeback.h> |
64 | #include <linux/memcontrol.h> |
65 | #include <linux/mmu_notifier.h> |
66 | #include <linux/swapops.h> |
67 | #include <linux/elf.h> |
68 | #include <linux/gfp.h> |
69 | #include <linux/migrate.h> |
70 | #include <linux/string.h> |
71 | #include <linux/memory-tiers.h> |
72 | #include <linux/debugfs.h> |
73 | #include <linux/userfaultfd_k.h> |
74 | #include <linux/dax.h> |
75 | #include <linux/oom.h> |
76 | #include <linux/numa.h> |
77 | #include <linux/perf_event.h> |
78 | #include <linux/ptrace.h> |
79 | #include <linux/vmalloc.h> |
80 | #include <linux/sched/sysctl.h> |
81 | |
82 | #include <trace/events/kmem.h> |
83 | |
84 | #include <asm/io.h> |
85 | #include <asm/mmu_context.h> |
86 | #include <asm/pgalloc.h> |
87 | #include <linux/uaccess.h> |
88 | #include <asm/tlb.h> |
89 | #include <asm/tlbflush.h> |
90 | |
91 | #include "pgalloc-track.h" |
92 | #include "internal.h" |
93 | #include "swap.h" |
94 | |
95 | #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST) |
96 | #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. |
97 | #endif |
98 | |
99 | #ifndef CONFIG_NUMA |
100 | unsigned long max_mapnr; |
101 | EXPORT_SYMBOL(max_mapnr); |
102 | |
103 | struct page *mem_map; |
104 | EXPORT_SYMBOL(mem_map); |
105 | #endif |
106 | |
107 | static vm_fault_t do_fault(struct vm_fault *vmf); |
108 | static vm_fault_t do_anonymous_page(struct vm_fault *vmf); |
109 | static bool vmf_pte_changed(struct vm_fault *vmf); |
110 | |
111 | /* |
112 | * Return true if the original pte was a uffd-wp pte marker (so the pte was |
113 | * wr-protected). |
114 | */ |
115 | static bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf) |
116 | { |
117 | if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) |
118 | return false; |
119 | |
120 | return pte_marker_uffd_wp(pte: vmf->orig_pte); |
121 | } |
122 | |
123 | /* |
124 | * A number of key systems in x86 including ioremap() rely on the assumption |
125 | * that high_memory defines the upper bound on direct map memory, then end |
126 | * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and |
127 | * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL |
128 | * and ZONE_HIGHMEM. |
129 | */ |
130 | void *high_memory; |
131 | EXPORT_SYMBOL(high_memory); |
132 | |
133 | /* |
134 | * Randomize the address space (stacks, mmaps, brk, etc.). |
135 | * |
136 | * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
137 | * as ancient (libc5 based) binaries can segfault. ) |
138 | */ |
139 | int randomize_va_space __read_mostly = |
140 | #ifdef CONFIG_COMPAT_BRK |
141 | 1; |
142 | #else |
143 | 2; |
144 | #endif |
145 | |
146 | #ifndef arch_wants_old_prefaulted_pte |
147 | static inline bool arch_wants_old_prefaulted_pte(void) |
148 | { |
149 | /* |
150 | * Transitioning a PTE from 'old' to 'young' can be expensive on |
151 | * some architectures, even if it's performed in hardware. By |
152 | * default, "false" means prefaulted entries will be 'young'. |
153 | */ |
154 | return false; |
155 | } |
156 | #endif |
157 | |
158 | static int __init disable_randmaps(char *s) |
159 | { |
160 | randomize_va_space = 0; |
161 | return 1; |
162 | } |
163 | __setup("norandmaps" , disable_randmaps); |
164 | |
165 | unsigned long zero_pfn __read_mostly; |
166 | EXPORT_SYMBOL(zero_pfn); |
167 | |
168 | unsigned long highest_memmap_pfn __read_mostly; |
169 | |
170 | /* |
171 | * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
172 | */ |
173 | static int __init init_zero_pfn(void) |
174 | { |
175 | zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
176 | return 0; |
177 | } |
178 | early_initcall(init_zero_pfn); |
179 | |
180 | void (struct mm_struct *mm, int member) |
181 | { |
182 | trace_rss_stat(mm, member); |
183 | } |
184 | |
185 | /* |
186 | * Note: this doesn't free the actual pages themselves. That |
187 | * has been handled earlier when unmapping all the memory regions. |
188 | */ |
189 | static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
190 | unsigned long addr) |
191 | { |
192 | pgtable_t token = pmd_pgtable(*pmd); |
193 | pmd_clear(pmdp: pmd); |
194 | pte_free_tlb(tlb, token, addr); |
195 | mm_dec_nr_ptes(mm: tlb->mm); |
196 | } |
197 | |
198 | static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
199 | unsigned long addr, unsigned long end, |
200 | unsigned long floor, unsigned long ceiling) |
201 | { |
202 | pmd_t *pmd; |
203 | unsigned long next; |
204 | unsigned long start; |
205 | |
206 | start = addr; |
207 | pmd = pmd_offset(pud, address: addr); |
208 | do { |
209 | next = pmd_addr_end(addr, end); |
210 | if (pmd_none_or_clear_bad(pmd)) |
211 | continue; |
212 | free_pte_range(tlb, pmd, addr); |
213 | } while (pmd++, addr = next, addr != end); |
214 | |
215 | start &= PUD_MASK; |
216 | if (start < floor) |
217 | return; |
218 | if (ceiling) { |
219 | ceiling &= PUD_MASK; |
220 | if (!ceiling) |
221 | return; |
222 | } |
223 | if (end - 1 > ceiling - 1) |
224 | return; |
225 | |
226 | pmd = pmd_offset(pud, address: start); |
227 | pud_clear(pudp: pud); |
228 | pmd_free_tlb(tlb, pmd, start); |
229 | mm_dec_nr_pmds(mm: tlb->mm); |
230 | } |
231 | |
232 | static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, |
233 | unsigned long addr, unsigned long end, |
234 | unsigned long floor, unsigned long ceiling) |
235 | { |
236 | pud_t *pud; |
237 | unsigned long next; |
238 | unsigned long start; |
239 | |
240 | start = addr; |
241 | pud = pud_offset(p4d, address: addr); |
242 | do { |
243 | next = pud_addr_end(addr, end); |
244 | if (pud_none_or_clear_bad(pud)) |
245 | continue; |
246 | free_pmd_range(tlb, pud, addr, end: next, floor, ceiling); |
247 | } while (pud++, addr = next, addr != end); |
248 | |
249 | start &= P4D_MASK; |
250 | if (start < floor) |
251 | return; |
252 | if (ceiling) { |
253 | ceiling &= P4D_MASK; |
254 | if (!ceiling) |
255 | return; |
256 | } |
257 | if (end - 1 > ceiling - 1) |
258 | return; |
259 | |
260 | pud = pud_offset(p4d, address: start); |
261 | p4d_clear(p4dp: p4d); |
262 | pud_free_tlb(tlb, pud, start); |
263 | mm_dec_nr_puds(mm: tlb->mm); |
264 | } |
265 | |
266 | static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, |
267 | unsigned long addr, unsigned long end, |
268 | unsigned long floor, unsigned long ceiling) |
269 | { |
270 | p4d_t *p4d; |
271 | unsigned long next; |
272 | unsigned long start; |
273 | |
274 | start = addr; |
275 | p4d = p4d_offset(pgd, address: addr); |
276 | do { |
277 | next = p4d_addr_end(addr, end); |
278 | if (p4d_none_or_clear_bad(p4d)) |
279 | continue; |
280 | free_pud_range(tlb, p4d, addr, end: next, floor, ceiling); |
281 | } while (p4d++, addr = next, addr != end); |
282 | |
283 | start &= PGDIR_MASK; |
284 | if (start < floor) |
285 | return; |
286 | if (ceiling) { |
287 | ceiling &= PGDIR_MASK; |
288 | if (!ceiling) |
289 | return; |
290 | } |
291 | if (end - 1 > ceiling - 1) |
292 | return; |
293 | |
294 | p4d = p4d_offset(pgd, address: start); |
295 | pgd_clear(pgd); |
296 | p4d_free_tlb(tlb, p4d, start); |
297 | } |
298 | |
299 | /* |
300 | * This function frees user-level page tables of a process. |
301 | */ |
302 | void free_pgd_range(struct mmu_gather *tlb, |
303 | unsigned long addr, unsigned long end, |
304 | unsigned long floor, unsigned long ceiling) |
305 | { |
306 | pgd_t *pgd; |
307 | unsigned long next; |
308 | |
309 | /* |
310 | * The next few lines have given us lots of grief... |
311 | * |
312 | * Why are we testing PMD* at this top level? Because often |
313 | * there will be no work to do at all, and we'd prefer not to |
314 | * go all the way down to the bottom just to discover that. |
315 | * |
316 | * Why all these "- 1"s? Because 0 represents both the bottom |
317 | * of the address space and the top of it (using -1 for the |
318 | * top wouldn't help much: the masks would do the wrong thing). |
319 | * The rule is that addr 0 and floor 0 refer to the bottom of |
320 | * the address space, but end 0 and ceiling 0 refer to the top |
321 | * Comparisons need to use "end - 1" and "ceiling - 1" (though |
322 | * that end 0 case should be mythical). |
323 | * |
324 | * Wherever addr is brought up or ceiling brought down, we must |
325 | * be careful to reject "the opposite 0" before it confuses the |
326 | * subsequent tests. But what about where end is brought down |
327 | * by PMD_SIZE below? no, end can't go down to 0 there. |
328 | * |
329 | * Whereas we round start (addr) and ceiling down, by different |
330 | * masks at different levels, in order to test whether a table |
331 | * now has no other vmas using it, so can be freed, we don't |
332 | * bother to round floor or end up - the tests don't need that. |
333 | */ |
334 | |
335 | addr &= PMD_MASK; |
336 | if (addr < floor) { |
337 | addr += PMD_SIZE; |
338 | if (!addr) |
339 | return; |
340 | } |
341 | if (ceiling) { |
342 | ceiling &= PMD_MASK; |
343 | if (!ceiling) |
344 | return; |
345 | } |
346 | if (end - 1 > ceiling - 1) |
347 | end -= PMD_SIZE; |
348 | if (addr > end - 1) |
349 | return; |
350 | /* |
351 | * We add page table cache pages with PAGE_SIZE, |
352 | * (see pte_free_tlb()), flush the tlb if we need |
353 | */ |
354 | tlb_change_page_size(tlb, PAGE_SIZE); |
355 | pgd = pgd_offset(tlb->mm, addr); |
356 | do { |
357 | next = pgd_addr_end(addr, end); |
358 | if (pgd_none_or_clear_bad(pgd)) |
359 | continue; |
360 | free_p4d_range(tlb, pgd, addr, end: next, floor, ceiling); |
361 | } while (pgd++, addr = next, addr != end); |
362 | } |
363 | |
364 | void free_pgtables(struct mmu_gather *tlb, struct ma_state *mas, |
365 | struct vm_area_struct *vma, unsigned long floor, |
366 | unsigned long ceiling, bool mm_wr_locked) |
367 | { |
368 | do { |
369 | unsigned long addr = vma->vm_start; |
370 | struct vm_area_struct *next; |
371 | |
372 | /* |
373 | * Note: USER_PGTABLES_CEILING may be passed as ceiling and may |
374 | * be 0. This will underflow and is okay. |
375 | */ |
376 | next = mas_find(mas, max: ceiling - 1); |
377 | |
378 | /* |
379 | * Hide vma from rmap and truncate_pagecache before freeing |
380 | * pgtables |
381 | */ |
382 | if (mm_wr_locked) |
383 | vma_start_write(vma); |
384 | unlink_anon_vmas(vma); |
385 | unlink_file_vma(vma); |
386 | |
387 | if (is_vm_hugetlb_page(vma)) { |
388 | hugetlb_free_pgd_range(tlb, addr, end: vma->vm_end, |
389 | floor, ceiling: next ? next->vm_start : ceiling); |
390 | } else { |
391 | /* |
392 | * Optimization: gather nearby vmas into one call down |
393 | */ |
394 | while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
395 | && !is_vm_hugetlb_page(vma: next)) { |
396 | vma = next; |
397 | next = mas_find(mas, max: ceiling - 1); |
398 | if (mm_wr_locked) |
399 | vma_start_write(vma); |
400 | unlink_anon_vmas(vma); |
401 | unlink_file_vma(vma); |
402 | } |
403 | free_pgd_range(tlb, addr, end: vma->vm_end, |
404 | floor, ceiling: next ? next->vm_start : ceiling); |
405 | } |
406 | vma = next; |
407 | } while (vma); |
408 | } |
409 | |
410 | void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte) |
411 | { |
412 | spinlock_t *ptl = pmd_lock(mm, pmd); |
413 | |
414 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
415 | mm_inc_nr_ptes(mm); |
416 | /* |
417 | * Ensure all pte setup (eg. pte page lock and page clearing) are |
418 | * visible before the pte is made visible to other CPUs by being |
419 | * put into page tables. |
420 | * |
421 | * The other side of the story is the pointer chasing in the page |
422 | * table walking code (when walking the page table without locking; |
423 | * ie. most of the time). Fortunately, these data accesses consist |
424 | * of a chain of data-dependent loads, meaning most CPUs (alpha |
425 | * being the notable exception) will already guarantee loads are |
426 | * seen in-order. See the alpha page table accessors for the |
427 | * smp_rmb() barriers in page table walking code. |
428 | */ |
429 | smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
430 | pmd_populate(mm, pmd, pte: *pte); |
431 | *pte = NULL; |
432 | } |
433 | spin_unlock(lock: ptl); |
434 | } |
435 | |
436 | int __pte_alloc(struct mm_struct *mm, pmd_t *pmd) |
437 | { |
438 | pgtable_t new = pte_alloc_one(mm); |
439 | if (!new) |
440 | return -ENOMEM; |
441 | |
442 | pmd_install(mm, pmd, pte: &new); |
443 | if (new) |
444 | pte_free(mm, pte_page: new); |
445 | return 0; |
446 | } |
447 | |
448 | int __pte_alloc_kernel(pmd_t *pmd) |
449 | { |
450 | pte_t *new = pte_alloc_one_kernel(mm: &init_mm); |
451 | if (!new) |
452 | return -ENOMEM; |
453 | |
454 | spin_lock(lock: &init_mm.page_table_lock); |
455 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
456 | smp_wmb(); /* See comment in pmd_install() */ |
457 | pmd_populate_kernel(mm: &init_mm, pmd, pte: new); |
458 | new = NULL; |
459 | } |
460 | spin_unlock(lock: &init_mm.page_table_lock); |
461 | if (new) |
462 | pte_free_kernel(mm: &init_mm, pte: new); |
463 | return 0; |
464 | } |
465 | |
466 | static inline void (int *) |
467 | { |
468 | memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); |
469 | } |
470 | |
471 | static inline void (struct mm_struct *mm, int *) |
472 | { |
473 | int i; |
474 | |
475 | for (i = 0; i < NR_MM_COUNTERS; i++) |
476 | if (rss[i]) |
477 | add_mm_counter(mm, member: i, value: rss[i]); |
478 | } |
479 | |
480 | /* |
481 | * This function is called to print an error when a bad pte |
482 | * is found. For example, we might have a PFN-mapped pte in |
483 | * a region that doesn't allow it. |
484 | * |
485 | * The calling function must still handle the error. |
486 | */ |
487 | static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
488 | pte_t pte, struct page *page) |
489 | { |
490 | pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
491 | p4d_t *p4d = p4d_offset(pgd, address: addr); |
492 | pud_t *pud = pud_offset(p4d, address: addr); |
493 | pmd_t *pmd = pmd_offset(pud, address: addr); |
494 | struct address_space *mapping; |
495 | pgoff_t index; |
496 | static unsigned long resume; |
497 | static unsigned long nr_shown; |
498 | static unsigned long nr_unshown; |
499 | |
500 | /* |
501 | * Allow a burst of 60 reports, then keep quiet for that minute; |
502 | * or allow a steady drip of one report per second. |
503 | */ |
504 | if (nr_shown == 60) { |
505 | if (time_before(jiffies, resume)) { |
506 | nr_unshown++; |
507 | return; |
508 | } |
509 | if (nr_unshown) { |
510 | pr_alert("BUG: Bad page map: %lu messages suppressed\n" , |
511 | nr_unshown); |
512 | nr_unshown = 0; |
513 | } |
514 | nr_shown = 0; |
515 | } |
516 | if (nr_shown++ == 0) |
517 | resume = jiffies + 60 * HZ; |
518 | |
519 | mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
520 | index = linear_page_index(vma, address: addr); |
521 | |
522 | pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n" , |
523 | current->comm, |
524 | (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
525 | if (page) |
526 | dump_page(page, reason: "bad pte" ); |
527 | pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n" , |
528 | (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
529 | pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n" , |
530 | vma->vm_file, |
531 | vma->vm_ops ? vma->vm_ops->fault : NULL, |
532 | vma->vm_file ? vma->vm_file->f_op->mmap : NULL, |
533 | mapping ? mapping->a_ops->read_folio : NULL); |
534 | dump_stack(); |
535 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
536 | } |
537 | |
538 | /* |
539 | * vm_normal_page -- This function gets the "struct page" associated with a pte. |
540 | * |
541 | * "Special" mappings do not wish to be associated with a "struct page" (either |
542 | * it doesn't exist, or it exists but they don't want to touch it). In this |
543 | * case, NULL is returned here. "Normal" mappings do have a struct page. |
544 | * |
545 | * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
546 | * pte bit, in which case this function is trivial. Secondly, an architecture |
547 | * may not have a spare pte bit, which requires a more complicated scheme, |
548 | * described below. |
549 | * |
550 | * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
551 | * special mapping (even if there are underlying and valid "struct pages"). |
552 | * COWed pages of a VM_PFNMAP are always normal. |
553 | * |
554 | * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
555 | * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
556 | * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
557 | * mapping will always honor the rule |
558 | * |
559 | * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
560 | * |
561 | * And for normal mappings this is false. |
562 | * |
563 | * This restricts such mappings to be a linear translation from virtual address |
564 | * to pfn. To get around this restriction, we allow arbitrary mappings so long |
565 | * as the vma is not a COW mapping; in that case, we know that all ptes are |
566 | * special (because none can have been COWed). |
567 | * |
568 | * |
569 | * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
570 | * |
571 | * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
572 | * page" backing, however the difference is that _all_ pages with a struct |
573 | * page (that is, those where pfn_valid is true) are refcounted and considered |
574 | * normal pages by the VM. The disadvantage is that pages are refcounted |
575 | * (which can be slower and simply not an option for some PFNMAP users). The |
576 | * advantage is that we don't have to follow the strict linearity rule of |
577 | * PFNMAP mappings in order to support COWable mappings. |
578 | * |
579 | */ |
580 | struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
581 | pte_t pte) |
582 | { |
583 | unsigned long pfn = pte_pfn(pte); |
584 | |
585 | if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { |
586 | if (likely(!pte_special(pte))) |
587 | goto check_pfn; |
588 | if (vma->vm_ops && vma->vm_ops->find_special_page) |
589 | return vma->vm_ops->find_special_page(vma, addr); |
590 | if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
591 | return NULL; |
592 | if (is_zero_pfn(pfn)) |
593 | return NULL; |
594 | if (pte_devmap(a: pte)) |
595 | /* |
596 | * NOTE: New users of ZONE_DEVICE will not set pte_devmap() |
597 | * and will have refcounts incremented on their struct pages |
598 | * when they are inserted into PTEs, thus they are safe to |
599 | * return here. Legacy ZONE_DEVICE pages that set pte_devmap() |
600 | * do not have refcounts. Example of legacy ZONE_DEVICE is |
601 | * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. |
602 | */ |
603 | return NULL; |
604 | |
605 | print_bad_pte(vma, addr, pte, NULL); |
606 | return NULL; |
607 | } |
608 | |
609 | /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ |
610 | |
611 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
612 | if (vma->vm_flags & VM_MIXEDMAP) { |
613 | if (!pfn_valid(pfn)) |
614 | return NULL; |
615 | goto out; |
616 | } else { |
617 | unsigned long off; |
618 | off = (addr - vma->vm_start) >> PAGE_SHIFT; |
619 | if (pfn == vma->vm_pgoff + off) |
620 | return NULL; |
621 | if (!is_cow_mapping(flags: vma->vm_flags)) |
622 | return NULL; |
623 | } |
624 | } |
625 | |
626 | if (is_zero_pfn(pfn)) |
627 | return NULL; |
628 | |
629 | check_pfn: |
630 | if (unlikely(pfn > highest_memmap_pfn)) { |
631 | print_bad_pte(vma, addr, pte, NULL); |
632 | return NULL; |
633 | } |
634 | |
635 | /* |
636 | * NOTE! We still have PageReserved() pages in the page tables. |
637 | * eg. VDSO mappings can cause them to exist. |
638 | */ |
639 | out: |
640 | return pfn_to_page(pfn); |
641 | } |
642 | |
643 | struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr, |
644 | pte_t pte) |
645 | { |
646 | struct page *page = vm_normal_page(vma, addr, pte); |
647 | |
648 | if (page) |
649 | return page_folio(page); |
650 | return NULL; |
651 | } |
652 | |
653 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
654 | struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, |
655 | pmd_t pmd) |
656 | { |
657 | unsigned long pfn = pmd_pfn(pmd); |
658 | |
659 | /* |
660 | * There is no pmd_special() but there may be special pmds, e.g. |
661 | * in a direct-access (dax) mapping, so let's just replicate the |
662 | * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. |
663 | */ |
664 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
665 | if (vma->vm_flags & VM_MIXEDMAP) { |
666 | if (!pfn_valid(pfn)) |
667 | return NULL; |
668 | goto out; |
669 | } else { |
670 | unsigned long off; |
671 | off = (addr - vma->vm_start) >> PAGE_SHIFT; |
672 | if (pfn == vma->vm_pgoff + off) |
673 | return NULL; |
674 | if (!is_cow_mapping(flags: vma->vm_flags)) |
675 | return NULL; |
676 | } |
677 | } |
678 | |
679 | if (pmd_devmap(pmd)) |
680 | return NULL; |
681 | if (is_huge_zero_pmd(pmd)) |
682 | return NULL; |
683 | if (unlikely(pfn > highest_memmap_pfn)) |
684 | return NULL; |
685 | |
686 | /* |
687 | * NOTE! We still have PageReserved() pages in the page tables. |
688 | * eg. VDSO mappings can cause them to exist. |
689 | */ |
690 | out: |
691 | return pfn_to_page(pfn); |
692 | } |
693 | |
694 | struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma, |
695 | unsigned long addr, pmd_t pmd) |
696 | { |
697 | struct page *page = vm_normal_page_pmd(vma, addr, pmd); |
698 | |
699 | if (page) |
700 | return page_folio(page); |
701 | return NULL; |
702 | } |
703 | #endif |
704 | |
705 | static void restore_exclusive_pte(struct vm_area_struct *vma, |
706 | struct page *page, unsigned long address, |
707 | pte_t *ptep) |
708 | { |
709 | pte_t orig_pte; |
710 | pte_t pte; |
711 | swp_entry_t entry; |
712 | |
713 | orig_pte = ptep_get(ptep); |
714 | pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); |
715 | if (pte_swp_soft_dirty(pte: orig_pte)) |
716 | pte = pte_mksoft_dirty(pte); |
717 | |
718 | entry = pte_to_swp_entry(pte: orig_pte); |
719 | if (pte_swp_uffd_wp(pte: orig_pte)) |
720 | pte = pte_mkuffd_wp(pte); |
721 | else if (is_writable_device_exclusive_entry(entry)) |
722 | pte = maybe_mkwrite(pte: pte_mkdirty(pte), vma); |
723 | |
724 | VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page))); |
725 | |
726 | /* |
727 | * No need to take a page reference as one was already |
728 | * created when the swap entry was made. |
729 | */ |
730 | if (PageAnon(page)) |
731 | page_add_anon_rmap(page, vma, address, RMAP_NONE); |
732 | else |
733 | /* |
734 | * Currently device exclusive access only supports anonymous |
735 | * memory so the entry shouldn't point to a filebacked page. |
736 | */ |
737 | WARN_ON_ONCE(1); |
738 | |
739 | set_pte_at(vma->vm_mm, address, ptep, pte); |
740 | |
741 | /* |
742 | * No need to invalidate - it was non-present before. However |
743 | * secondary CPUs may have mappings that need invalidating. |
744 | */ |
745 | update_mmu_cache(vma, addr: address, ptep); |
746 | } |
747 | |
748 | /* |
749 | * Tries to restore an exclusive pte if the page lock can be acquired without |
750 | * sleeping. |
751 | */ |
752 | static int |
753 | try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, |
754 | unsigned long addr) |
755 | { |
756 | swp_entry_t entry = pte_to_swp_entry(pte: ptep_get(ptep: src_pte)); |
757 | struct page *page = pfn_swap_entry_to_page(entry); |
758 | |
759 | if (trylock_page(page)) { |
760 | restore_exclusive_pte(vma, page, address: addr, ptep: src_pte); |
761 | unlock_page(page); |
762 | return 0; |
763 | } |
764 | |
765 | return -EBUSY; |
766 | } |
767 | |
768 | /* |
769 | * copy one vm_area from one task to the other. Assumes the page tables |
770 | * already present in the new task to be cleared in the whole range |
771 | * covered by this vma. |
772 | */ |
773 | |
774 | static unsigned long |
775 | copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
776 | pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, |
777 | struct vm_area_struct *src_vma, unsigned long addr, int *) |
778 | { |
779 | unsigned long vm_flags = dst_vma->vm_flags; |
780 | pte_t orig_pte = ptep_get(ptep: src_pte); |
781 | pte_t pte = orig_pte; |
782 | struct page *page; |
783 | swp_entry_t entry = pte_to_swp_entry(pte: orig_pte); |
784 | |
785 | if (likely(!non_swap_entry(entry))) { |
786 | if (swap_duplicate(entry) < 0) |
787 | return -EIO; |
788 | |
789 | /* make sure dst_mm is on swapoff's mmlist. */ |
790 | if (unlikely(list_empty(&dst_mm->mmlist))) { |
791 | spin_lock(lock: &mmlist_lock); |
792 | if (list_empty(head: &dst_mm->mmlist)) |
793 | list_add(new: &dst_mm->mmlist, |
794 | head: &src_mm->mmlist); |
795 | spin_unlock(lock: &mmlist_lock); |
796 | } |
797 | /* Mark the swap entry as shared. */ |
798 | if (pte_swp_exclusive(pte: orig_pte)) { |
799 | pte = pte_swp_clear_exclusive(pte: orig_pte); |
800 | set_pte_at(src_mm, addr, src_pte, pte); |
801 | } |
802 | rss[MM_SWAPENTS]++; |
803 | } else if (is_migration_entry(entry)) { |
804 | page = pfn_swap_entry_to_page(entry); |
805 | |
806 | rss[mm_counter(page)]++; |
807 | |
808 | if (!is_readable_migration_entry(entry) && |
809 | is_cow_mapping(flags: vm_flags)) { |
810 | /* |
811 | * COW mappings require pages in both parent and child |
812 | * to be set to read. A previously exclusive entry is |
813 | * now shared. |
814 | */ |
815 | entry = make_readable_migration_entry( |
816 | offset: swp_offset(entry)); |
817 | pte = swp_entry_to_pte(entry); |
818 | if (pte_swp_soft_dirty(pte: orig_pte)) |
819 | pte = pte_swp_mksoft_dirty(pte); |
820 | if (pte_swp_uffd_wp(pte: orig_pte)) |
821 | pte = pte_swp_mkuffd_wp(pte); |
822 | set_pte_at(src_mm, addr, src_pte, pte); |
823 | } |
824 | } else if (is_device_private_entry(entry)) { |
825 | page = pfn_swap_entry_to_page(entry); |
826 | |
827 | /* |
828 | * Update rss count even for unaddressable pages, as |
829 | * they should treated just like normal pages in this |
830 | * respect. |
831 | * |
832 | * We will likely want to have some new rss counters |
833 | * for unaddressable pages, at some point. But for now |
834 | * keep things as they are. |
835 | */ |
836 | get_page(page); |
837 | rss[mm_counter(page)]++; |
838 | /* Cannot fail as these pages cannot get pinned. */ |
839 | BUG_ON(page_try_dup_anon_rmap(page, false, src_vma)); |
840 | |
841 | /* |
842 | * We do not preserve soft-dirty information, because so |
843 | * far, checkpoint/restore is the only feature that |
844 | * requires that. And checkpoint/restore does not work |
845 | * when a device driver is involved (you cannot easily |
846 | * save and restore device driver state). |
847 | */ |
848 | if (is_writable_device_private_entry(entry) && |
849 | is_cow_mapping(flags: vm_flags)) { |
850 | entry = make_readable_device_private_entry( |
851 | offset: swp_offset(entry)); |
852 | pte = swp_entry_to_pte(entry); |
853 | if (pte_swp_uffd_wp(pte: orig_pte)) |
854 | pte = pte_swp_mkuffd_wp(pte); |
855 | set_pte_at(src_mm, addr, src_pte, pte); |
856 | } |
857 | } else if (is_device_exclusive_entry(entry)) { |
858 | /* |
859 | * Make device exclusive entries present by restoring the |
860 | * original entry then copying as for a present pte. Device |
861 | * exclusive entries currently only support private writable |
862 | * (ie. COW) mappings. |
863 | */ |
864 | VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); |
865 | if (try_restore_exclusive_pte(src_pte, vma: src_vma, addr)) |
866 | return -EBUSY; |
867 | return -ENOENT; |
868 | } else if (is_pte_marker_entry(entry)) { |
869 | pte_marker marker = copy_pte_marker(entry, dst_vma); |
870 | |
871 | if (marker) |
872 | set_pte_at(dst_mm, addr, dst_pte, |
873 | make_pte_marker(marker)); |
874 | return 0; |
875 | } |
876 | if (!userfaultfd_wp(vma: dst_vma)) |
877 | pte = pte_swp_clear_uffd_wp(pte); |
878 | set_pte_at(dst_mm, addr, dst_pte, pte); |
879 | return 0; |
880 | } |
881 | |
882 | /* |
883 | * Copy a present and normal page. |
884 | * |
885 | * NOTE! The usual case is that this isn't required; |
886 | * instead, the caller can just increase the page refcount |
887 | * and re-use the pte the traditional way. |
888 | * |
889 | * And if we need a pre-allocated page but don't yet have |
890 | * one, return a negative error to let the preallocation |
891 | * code know so that it can do so outside the page table |
892 | * lock. |
893 | */ |
894 | static inline int |
895 | copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
896 | pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *, |
897 | struct folio **prealloc, struct page *page) |
898 | { |
899 | struct folio *new_folio; |
900 | pte_t pte; |
901 | |
902 | new_folio = *prealloc; |
903 | if (!new_folio) |
904 | return -EAGAIN; |
905 | |
906 | /* |
907 | * We have a prealloc page, all good! Take it |
908 | * over and copy the page & arm it. |
909 | */ |
910 | *prealloc = NULL; |
911 | copy_user_highpage(to: &new_folio->page, from: page, vaddr: addr, vma: src_vma); |
912 | __folio_mark_uptodate(folio: new_folio); |
913 | folio_add_new_anon_rmap(new_folio, dst_vma, address: addr); |
914 | folio_add_lru_vma(new_folio, dst_vma); |
915 | rss[MM_ANONPAGES]++; |
916 | |
917 | /* All done, just insert the new page copy in the child */ |
918 | pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot); |
919 | pte = maybe_mkwrite(pte: pte_mkdirty(pte), vma: dst_vma); |
920 | if (userfaultfd_pte_wp(vma: dst_vma, pte: ptep_get(ptep: src_pte))) |
921 | /* Uffd-wp needs to be delivered to dest pte as well */ |
922 | pte = pte_mkuffd_wp(pte); |
923 | set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); |
924 | return 0; |
925 | } |
926 | |
927 | /* |
928 | * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page |
929 | * is required to copy this pte. |
930 | */ |
931 | static inline int |
932 | copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
933 | pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *, |
934 | struct folio **prealloc) |
935 | { |
936 | struct mm_struct *src_mm = src_vma->vm_mm; |
937 | unsigned long vm_flags = src_vma->vm_flags; |
938 | pte_t pte = ptep_get(ptep: src_pte); |
939 | struct page *page; |
940 | struct folio *folio; |
941 | |
942 | page = vm_normal_page(vma: src_vma, addr, pte); |
943 | if (page) |
944 | folio = page_folio(page); |
945 | if (page && folio_test_anon(folio)) { |
946 | /* |
947 | * If this page may have been pinned by the parent process, |
948 | * copy the page immediately for the child so that we'll always |
949 | * guarantee the pinned page won't be randomly replaced in the |
950 | * future. |
951 | */ |
952 | folio_get(folio); |
953 | if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) { |
954 | /* Page may be pinned, we have to copy. */ |
955 | folio_put(folio); |
956 | return copy_present_page(dst_vma, src_vma, dst_pte, src_pte, |
957 | addr, rss, prealloc, page); |
958 | } |
959 | rss[MM_ANONPAGES]++; |
960 | } else if (page) { |
961 | folio_get(folio); |
962 | page_dup_file_rmap(page, compound: false); |
963 | rss[mm_counter_file(page)]++; |
964 | } |
965 | |
966 | /* |
967 | * If it's a COW mapping, write protect it both |
968 | * in the parent and the child |
969 | */ |
970 | if (is_cow_mapping(flags: vm_flags) && pte_write(pte)) { |
971 | ptep_set_wrprotect(mm: src_mm, addr, ptep: src_pte); |
972 | pte = pte_wrprotect(pte); |
973 | } |
974 | VM_BUG_ON(page && folio_test_anon(folio) && PageAnonExclusive(page)); |
975 | |
976 | /* |
977 | * If it's a shared mapping, mark it clean in |
978 | * the child |
979 | */ |
980 | if (vm_flags & VM_SHARED) |
981 | pte = pte_mkclean(pte); |
982 | pte = pte_mkold(pte); |
983 | |
984 | if (!userfaultfd_wp(vma: dst_vma)) |
985 | pte = pte_clear_uffd_wp(pte); |
986 | |
987 | set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); |
988 | return 0; |
989 | } |
990 | |
991 | static inline struct folio *page_copy_prealloc(struct mm_struct *src_mm, |
992 | struct vm_area_struct *vma, unsigned long addr) |
993 | { |
994 | struct folio *new_folio; |
995 | |
996 | new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, order: 0, vma, addr, hugepage: false); |
997 | if (!new_folio) |
998 | return NULL; |
999 | |
1000 | if (mem_cgroup_charge(folio: new_folio, mm: src_mm, GFP_KERNEL)) { |
1001 | folio_put(folio: new_folio); |
1002 | return NULL; |
1003 | } |
1004 | folio_throttle_swaprate(folio: new_folio, GFP_KERNEL); |
1005 | |
1006 | return new_folio; |
1007 | } |
1008 | |
1009 | static int |
1010 | copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
1011 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, |
1012 | unsigned long end) |
1013 | { |
1014 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1015 | struct mm_struct *src_mm = src_vma->vm_mm; |
1016 | pte_t *orig_src_pte, *orig_dst_pte; |
1017 | pte_t *src_pte, *dst_pte; |
1018 | pte_t ptent; |
1019 | spinlock_t *src_ptl, *dst_ptl; |
1020 | int progress, ret = 0; |
1021 | int [NR_MM_COUNTERS]; |
1022 | swp_entry_t entry = (swp_entry_t){0}; |
1023 | struct folio *prealloc = NULL; |
1024 | |
1025 | again: |
1026 | progress = 0; |
1027 | init_rss_vec(rss); |
1028 | |
1029 | /* |
1030 | * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the |
1031 | * error handling here, assume that exclusive mmap_lock on dst and src |
1032 | * protects anon from unexpected THP transitions; with shmem and file |
1033 | * protected by mmap_lock-less collapse skipping areas with anon_vma |
1034 | * (whereas vma_needs_copy() skips areas without anon_vma). A rework |
1035 | * can remove such assumptions later, but this is good enough for now. |
1036 | */ |
1037 | dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
1038 | if (!dst_pte) { |
1039 | ret = -ENOMEM; |
1040 | goto out; |
1041 | } |
1042 | src_pte = pte_offset_map_nolock(mm: src_mm, pmd: src_pmd, addr, ptlp: &src_ptl); |
1043 | if (!src_pte) { |
1044 | pte_unmap_unlock(dst_pte, dst_ptl); |
1045 | /* ret == 0 */ |
1046 | goto out; |
1047 | } |
1048 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
1049 | orig_src_pte = src_pte; |
1050 | orig_dst_pte = dst_pte; |
1051 | arch_enter_lazy_mmu_mode(); |
1052 | |
1053 | do { |
1054 | /* |
1055 | * We are holding two locks at this point - either of them |
1056 | * could generate latencies in another task on another CPU. |
1057 | */ |
1058 | if (progress >= 32) { |
1059 | progress = 0; |
1060 | if (need_resched() || |
1061 | spin_needbreak(lock: src_ptl) || spin_needbreak(lock: dst_ptl)) |
1062 | break; |
1063 | } |
1064 | ptent = ptep_get(ptep: src_pte); |
1065 | if (pte_none(pte: ptent)) { |
1066 | progress++; |
1067 | continue; |
1068 | } |
1069 | if (unlikely(!pte_present(ptent))) { |
1070 | ret = copy_nonpresent_pte(dst_mm, src_mm, |
1071 | dst_pte, src_pte, |
1072 | dst_vma, src_vma, |
1073 | addr, rss); |
1074 | if (ret == -EIO) { |
1075 | entry = pte_to_swp_entry(pte: ptep_get(ptep: src_pte)); |
1076 | break; |
1077 | } else if (ret == -EBUSY) { |
1078 | break; |
1079 | } else if (!ret) { |
1080 | progress += 8; |
1081 | continue; |
1082 | } |
1083 | |
1084 | /* |
1085 | * Device exclusive entry restored, continue by copying |
1086 | * the now present pte. |
1087 | */ |
1088 | WARN_ON_ONCE(ret != -ENOENT); |
1089 | } |
1090 | /* copy_present_pte() will clear `*prealloc' if consumed */ |
1091 | ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte, |
1092 | addr, rss, prealloc: &prealloc); |
1093 | /* |
1094 | * If we need a pre-allocated page for this pte, drop the |
1095 | * locks, allocate, and try again. |
1096 | */ |
1097 | if (unlikely(ret == -EAGAIN)) |
1098 | break; |
1099 | if (unlikely(prealloc)) { |
1100 | /* |
1101 | * pre-alloc page cannot be reused by next time so as |
1102 | * to strictly follow mempolicy (e.g., alloc_page_vma() |
1103 | * will allocate page according to address). This |
1104 | * could only happen if one pinned pte changed. |
1105 | */ |
1106 | folio_put(folio: prealloc); |
1107 | prealloc = NULL; |
1108 | } |
1109 | progress += 8; |
1110 | } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
1111 | |
1112 | arch_leave_lazy_mmu_mode(); |
1113 | pte_unmap_unlock(orig_src_pte, src_ptl); |
1114 | add_mm_rss_vec(mm: dst_mm, rss); |
1115 | pte_unmap_unlock(orig_dst_pte, dst_ptl); |
1116 | cond_resched(); |
1117 | |
1118 | if (ret == -EIO) { |
1119 | VM_WARN_ON_ONCE(!entry.val); |
1120 | if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { |
1121 | ret = -ENOMEM; |
1122 | goto out; |
1123 | } |
1124 | entry.val = 0; |
1125 | } else if (ret == -EBUSY) { |
1126 | goto out; |
1127 | } else if (ret == -EAGAIN) { |
1128 | prealloc = page_copy_prealloc(src_mm, vma: src_vma, addr); |
1129 | if (!prealloc) |
1130 | return -ENOMEM; |
1131 | } else if (ret) { |
1132 | VM_WARN_ON_ONCE(1); |
1133 | } |
1134 | |
1135 | /* We've captured and resolved the error. Reset, try again. */ |
1136 | ret = 0; |
1137 | |
1138 | if (addr != end) |
1139 | goto again; |
1140 | out: |
1141 | if (unlikely(prealloc)) |
1142 | folio_put(folio: prealloc); |
1143 | return ret; |
1144 | } |
1145 | |
1146 | static inline int |
1147 | copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
1148 | pud_t *dst_pud, pud_t *src_pud, unsigned long addr, |
1149 | unsigned long end) |
1150 | { |
1151 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1152 | struct mm_struct *src_mm = src_vma->vm_mm; |
1153 | pmd_t *src_pmd, *dst_pmd; |
1154 | unsigned long next; |
1155 | |
1156 | dst_pmd = pmd_alloc(mm: dst_mm, pud: dst_pud, address: addr); |
1157 | if (!dst_pmd) |
1158 | return -ENOMEM; |
1159 | src_pmd = pmd_offset(pud: src_pud, address: addr); |
1160 | do { |
1161 | next = pmd_addr_end(addr, end); |
1162 | if (is_swap_pmd(pmd: *src_pmd) || pmd_trans_huge(pmd: *src_pmd) |
1163 | || pmd_devmap(pmd: *src_pmd)) { |
1164 | int err; |
1165 | VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma); |
1166 | err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd, |
1167 | addr, dst_vma, src_vma); |
1168 | if (err == -ENOMEM) |
1169 | return -ENOMEM; |
1170 | if (!err) |
1171 | continue; |
1172 | /* fall through */ |
1173 | } |
1174 | if (pmd_none_or_clear_bad(pmd: src_pmd)) |
1175 | continue; |
1176 | if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd, |
1177 | addr, end: next)) |
1178 | return -ENOMEM; |
1179 | } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
1180 | return 0; |
1181 | } |
1182 | |
1183 | static inline int |
1184 | copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
1185 | p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr, |
1186 | unsigned long end) |
1187 | { |
1188 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1189 | struct mm_struct *src_mm = src_vma->vm_mm; |
1190 | pud_t *src_pud, *dst_pud; |
1191 | unsigned long next; |
1192 | |
1193 | dst_pud = pud_alloc(mm: dst_mm, p4d: dst_p4d, address: addr); |
1194 | if (!dst_pud) |
1195 | return -ENOMEM; |
1196 | src_pud = pud_offset(p4d: src_p4d, address: addr); |
1197 | do { |
1198 | next = pud_addr_end(addr, end); |
1199 | if (pud_trans_huge(pud: *src_pud) || pud_devmap(pud: *src_pud)) { |
1200 | int err; |
1201 | |
1202 | VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma); |
1203 | err = copy_huge_pud(dst_mm, src_mm, |
1204 | dst_pud, src_pud, addr, vma: src_vma); |
1205 | if (err == -ENOMEM) |
1206 | return -ENOMEM; |
1207 | if (!err) |
1208 | continue; |
1209 | /* fall through */ |
1210 | } |
1211 | if (pud_none_or_clear_bad(pud: src_pud)) |
1212 | continue; |
1213 | if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud, |
1214 | addr, end: next)) |
1215 | return -ENOMEM; |
1216 | } while (dst_pud++, src_pud++, addr = next, addr != end); |
1217 | return 0; |
1218 | } |
1219 | |
1220 | static inline int |
1221 | copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
1222 | pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr, |
1223 | unsigned long end) |
1224 | { |
1225 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1226 | p4d_t *src_p4d, *dst_p4d; |
1227 | unsigned long next; |
1228 | |
1229 | dst_p4d = p4d_alloc(mm: dst_mm, pgd: dst_pgd, address: addr); |
1230 | if (!dst_p4d) |
1231 | return -ENOMEM; |
1232 | src_p4d = p4d_offset(pgd: src_pgd, address: addr); |
1233 | do { |
1234 | next = p4d_addr_end(addr, end); |
1235 | if (p4d_none_or_clear_bad(p4d: src_p4d)) |
1236 | continue; |
1237 | if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d, |
1238 | addr, end: next)) |
1239 | return -ENOMEM; |
1240 | } while (dst_p4d++, src_p4d++, addr = next, addr != end); |
1241 | return 0; |
1242 | } |
1243 | |
1244 | /* |
1245 | * Return true if the vma needs to copy the pgtable during this fork(). Return |
1246 | * false when we can speed up fork() by allowing lazy page faults later until |
1247 | * when the child accesses the memory range. |
1248 | */ |
1249 | static bool |
1250 | vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
1251 | { |
1252 | /* |
1253 | * Always copy pgtables when dst_vma has uffd-wp enabled even if it's |
1254 | * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable |
1255 | * contains uffd-wp protection information, that's something we can't |
1256 | * retrieve from page cache, and skip copying will lose those info. |
1257 | */ |
1258 | if (userfaultfd_wp(vma: dst_vma)) |
1259 | return true; |
1260 | |
1261 | if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
1262 | return true; |
1263 | |
1264 | if (src_vma->anon_vma) |
1265 | return true; |
1266 | |
1267 | /* |
1268 | * Don't copy ptes where a page fault will fill them correctly. Fork |
1269 | * becomes much lighter when there are big shared or private readonly |
1270 | * mappings. The tradeoff is that copy_page_range is more efficient |
1271 | * than faulting. |
1272 | */ |
1273 | return false; |
1274 | } |
1275 | |
1276 | int |
1277 | copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
1278 | { |
1279 | pgd_t *src_pgd, *dst_pgd; |
1280 | unsigned long next; |
1281 | unsigned long addr = src_vma->vm_start; |
1282 | unsigned long end = src_vma->vm_end; |
1283 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1284 | struct mm_struct *src_mm = src_vma->vm_mm; |
1285 | struct mmu_notifier_range range; |
1286 | bool is_cow; |
1287 | int ret; |
1288 | |
1289 | if (!vma_needs_copy(dst_vma, src_vma)) |
1290 | return 0; |
1291 | |
1292 | if (is_vm_hugetlb_page(vma: src_vma)) |
1293 | return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma); |
1294 | |
1295 | if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { |
1296 | /* |
1297 | * We do not free on error cases below as remove_vma |
1298 | * gets called on error from higher level routine |
1299 | */ |
1300 | ret = track_pfn_copy(vma: src_vma); |
1301 | if (ret) |
1302 | return ret; |
1303 | } |
1304 | |
1305 | /* |
1306 | * We need to invalidate the secondary MMU mappings only when |
1307 | * there could be a permission downgrade on the ptes of the |
1308 | * parent mm. And a permission downgrade will only happen if |
1309 | * is_cow_mapping() returns true. |
1310 | */ |
1311 | is_cow = is_cow_mapping(flags: src_vma->vm_flags); |
1312 | |
1313 | if (is_cow) { |
1314 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_PROTECTION_PAGE, |
1315 | flags: 0, mm: src_mm, start: addr, end); |
1316 | mmu_notifier_invalidate_range_start(range: &range); |
1317 | /* |
1318 | * Disabling preemption is not needed for the write side, as |
1319 | * the read side doesn't spin, but goes to the mmap_lock. |
1320 | * |
1321 | * Use the raw variant of the seqcount_t write API to avoid |
1322 | * lockdep complaining about preemptibility. |
1323 | */ |
1324 | vma_assert_write_locked(vma: src_vma); |
1325 | raw_write_seqcount_begin(&src_mm->write_protect_seq); |
1326 | } |
1327 | |
1328 | ret = 0; |
1329 | dst_pgd = pgd_offset(dst_mm, addr); |
1330 | src_pgd = pgd_offset(src_mm, addr); |
1331 | do { |
1332 | next = pgd_addr_end(addr, end); |
1333 | if (pgd_none_or_clear_bad(pgd: src_pgd)) |
1334 | continue; |
1335 | if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, |
1336 | addr, next))) { |
1337 | untrack_pfn_clear(vma: dst_vma); |
1338 | ret = -ENOMEM; |
1339 | break; |
1340 | } |
1341 | } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
1342 | |
1343 | if (is_cow) { |
1344 | raw_write_seqcount_end(&src_mm->write_protect_seq); |
1345 | mmu_notifier_invalidate_range_end(range: &range); |
1346 | } |
1347 | return ret; |
1348 | } |
1349 | |
1350 | /* Whether we should zap all COWed (private) pages too */ |
1351 | static inline bool should_zap_cows(struct zap_details *details) |
1352 | { |
1353 | /* By default, zap all pages */ |
1354 | if (!details) |
1355 | return true; |
1356 | |
1357 | /* Or, we zap COWed pages only if the caller wants to */ |
1358 | return details->even_cows; |
1359 | } |
1360 | |
1361 | /* Decides whether we should zap this page with the page pointer specified */ |
1362 | static inline bool should_zap_page(struct zap_details *details, struct page *page) |
1363 | { |
1364 | /* If we can make a decision without *page.. */ |
1365 | if (should_zap_cows(details)) |
1366 | return true; |
1367 | |
1368 | /* E.g. the caller passes NULL for the case of a zero page */ |
1369 | if (!page) |
1370 | return true; |
1371 | |
1372 | /* Otherwise we should only zap non-anon pages */ |
1373 | return !PageAnon(page); |
1374 | } |
1375 | |
1376 | static inline bool zap_drop_file_uffd_wp(struct zap_details *details) |
1377 | { |
1378 | if (!details) |
1379 | return false; |
1380 | |
1381 | return details->zap_flags & ZAP_FLAG_DROP_MARKER; |
1382 | } |
1383 | |
1384 | /* |
1385 | * This function makes sure that we'll replace the none pte with an uffd-wp |
1386 | * swap special pte marker when necessary. Must be with the pgtable lock held. |
1387 | */ |
1388 | static inline void |
1389 | zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, |
1390 | unsigned long addr, pte_t *pte, |
1391 | struct zap_details *details, pte_t pteval) |
1392 | { |
1393 | /* Zap on anonymous always means dropping everything */ |
1394 | if (vma_is_anonymous(vma)) |
1395 | return; |
1396 | |
1397 | if (zap_drop_file_uffd_wp(details)) |
1398 | return; |
1399 | |
1400 | pte_install_uffd_wp_if_needed(vma, addr, pte, pteval); |
1401 | } |
1402 | |
1403 | static unsigned long zap_pte_range(struct mmu_gather *tlb, |
1404 | struct vm_area_struct *vma, pmd_t *pmd, |
1405 | unsigned long addr, unsigned long end, |
1406 | struct zap_details *details) |
1407 | { |
1408 | struct mm_struct *mm = tlb->mm; |
1409 | int force_flush = 0; |
1410 | int [NR_MM_COUNTERS]; |
1411 | spinlock_t *ptl; |
1412 | pte_t *start_pte; |
1413 | pte_t *pte; |
1414 | swp_entry_t entry; |
1415 | |
1416 | tlb_change_page_size(tlb, PAGE_SIZE); |
1417 | init_rss_vec(rss); |
1418 | start_pte = pte = pte_offset_map_lock(mm, pmd, addr, ptlp: &ptl); |
1419 | if (!pte) |
1420 | return addr; |
1421 | |
1422 | flush_tlb_batched_pending(mm); |
1423 | arch_enter_lazy_mmu_mode(); |
1424 | do { |
1425 | pte_t ptent = ptep_get(ptep: pte); |
1426 | struct page *page; |
1427 | |
1428 | if (pte_none(pte: ptent)) |
1429 | continue; |
1430 | |
1431 | if (need_resched()) |
1432 | break; |
1433 | |
1434 | if (pte_present(a: ptent)) { |
1435 | unsigned int delay_rmap; |
1436 | |
1437 | page = vm_normal_page(vma, addr, pte: ptent); |
1438 | if (unlikely(!should_zap_page(details, page))) |
1439 | continue; |
1440 | ptent = ptep_get_and_clear_full(mm, addr, ptep: pte, |
1441 | full: tlb->fullmm); |
1442 | arch_check_zapped_pte(vma, pte: ptent); |
1443 | tlb_remove_tlb_entry(tlb, pte, addr); |
1444 | zap_install_uffd_wp_if_needed(vma, addr, pte, details, |
1445 | pteval: ptent); |
1446 | if (unlikely(!page)) { |
1447 | ksm_might_unmap_zero_page(mm, pte: ptent); |
1448 | continue; |
1449 | } |
1450 | |
1451 | delay_rmap = 0; |
1452 | if (!PageAnon(page)) { |
1453 | if (pte_dirty(pte: ptent)) { |
1454 | set_page_dirty(page); |
1455 | if (tlb_delay_rmap(tlb)) { |
1456 | delay_rmap = 1; |
1457 | force_flush = 1; |
1458 | } |
1459 | } |
1460 | if (pte_young(pte: ptent) && likely(vma_has_recency(vma))) |
1461 | mark_page_accessed(page); |
1462 | } |
1463 | rss[mm_counter(page)]--; |
1464 | if (!delay_rmap) { |
1465 | page_remove_rmap(page, vma, compound: false); |
1466 | if (unlikely(page_mapcount(page) < 0)) |
1467 | print_bad_pte(vma, addr, pte: ptent, page); |
1468 | } |
1469 | if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) { |
1470 | force_flush = 1; |
1471 | addr += PAGE_SIZE; |
1472 | break; |
1473 | } |
1474 | continue; |
1475 | } |
1476 | |
1477 | entry = pte_to_swp_entry(pte: ptent); |
1478 | if (is_device_private_entry(entry) || |
1479 | is_device_exclusive_entry(entry)) { |
1480 | page = pfn_swap_entry_to_page(entry); |
1481 | if (unlikely(!should_zap_page(details, page))) |
1482 | continue; |
1483 | /* |
1484 | * Both device private/exclusive mappings should only |
1485 | * work with anonymous page so far, so we don't need to |
1486 | * consider uffd-wp bit when zap. For more information, |
1487 | * see zap_install_uffd_wp_if_needed(). |
1488 | */ |
1489 | WARN_ON_ONCE(!vma_is_anonymous(vma)); |
1490 | rss[mm_counter(page)]--; |
1491 | if (is_device_private_entry(entry)) |
1492 | page_remove_rmap(page, vma, compound: false); |
1493 | put_page(page); |
1494 | } else if (!non_swap_entry(entry)) { |
1495 | /* Genuine swap entry, hence a private anon page */ |
1496 | if (!should_zap_cows(details)) |
1497 | continue; |
1498 | rss[MM_SWAPENTS]--; |
1499 | if (unlikely(!free_swap_and_cache(entry))) |
1500 | print_bad_pte(vma, addr, pte: ptent, NULL); |
1501 | } else if (is_migration_entry(entry)) { |
1502 | page = pfn_swap_entry_to_page(entry); |
1503 | if (!should_zap_page(details, page)) |
1504 | continue; |
1505 | rss[mm_counter(page)]--; |
1506 | } else if (pte_marker_entry_uffd_wp(entry)) { |
1507 | /* |
1508 | * For anon: always drop the marker; for file: only |
1509 | * drop the marker if explicitly requested. |
1510 | */ |
1511 | if (!vma_is_anonymous(vma) && |
1512 | !zap_drop_file_uffd_wp(details)) |
1513 | continue; |
1514 | } else if (is_hwpoison_entry(entry) || |
1515 | is_poisoned_swp_entry(entry)) { |
1516 | if (!should_zap_cows(details)) |
1517 | continue; |
1518 | } else { |
1519 | /* We should have covered all the swap entry types */ |
1520 | WARN_ON_ONCE(1); |
1521 | } |
1522 | pte_clear_not_present_full(mm, address: addr, ptep: pte, full: tlb->fullmm); |
1523 | zap_install_uffd_wp_if_needed(vma, addr, pte, details, pteval: ptent); |
1524 | } while (pte++, addr += PAGE_SIZE, addr != end); |
1525 | |
1526 | add_mm_rss_vec(mm, rss); |
1527 | arch_leave_lazy_mmu_mode(); |
1528 | |
1529 | /* Do the actual TLB flush before dropping ptl */ |
1530 | if (force_flush) { |
1531 | tlb_flush_mmu_tlbonly(tlb); |
1532 | tlb_flush_rmaps(tlb, vma); |
1533 | } |
1534 | pte_unmap_unlock(start_pte, ptl); |
1535 | |
1536 | /* |
1537 | * If we forced a TLB flush (either due to running out of |
1538 | * batch buffers or because we needed to flush dirty TLB |
1539 | * entries before releasing the ptl), free the batched |
1540 | * memory too. Come back again if we didn't do everything. |
1541 | */ |
1542 | if (force_flush) |
1543 | tlb_flush_mmu(tlb); |
1544 | |
1545 | return addr; |
1546 | } |
1547 | |
1548 | static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
1549 | struct vm_area_struct *vma, pud_t *pud, |
1550 | unsigned long addr, unsigned long end, |
1551 | struct zap_details *details) |
1552 | { |
1553 | pmd_t *pmd; |
1554 | unsigned long next; |
1555 | |
1556 | pmd = pmd_offset(pud, address: addr); |
1557 | do { |
1558 | next = pmd_addr_end(addr, end); |
1559 | if (is_swap_pmd(pmd: *pmd) || pmd_trans_huge(pmd: *pmd) || pmd_devmap(pmd: *pmd)) { |
1560 | if (next - addr != HPAGE_PMD_SIZE) |
1561 | __split_huge_pmd(vma, pmd, address: addr, freeze: false, NULL); |
1562 | else if (zap_huge_pmd(tlb, vma, pmd, addr)) { |
1563 | addr = next; |
1564 | continue; |
1565 | } |
1566 | /* fall through */ |
1567 | } else if (details && details->single_folio && |
1568 | folio_test_pmd_mappable(folio: details->single_folio) && |
1569 | next - addr == HPAGE_PMD_SIZE && pmd_none(pmd: *pmd)) { |
1570 | spinlock_t *ptl = pmd_lock(mm: tlb->mm, pmd); |
1571 | /* |
1572 | * Take and drop THP pmd lock so that we cannot return |
1573 | * prematurely, while zap_huge_pmd() has cleared *pmd, |
1574 | * but not yet decremented compound_mapcount(). |
1575 | */ |
1576 | spin_unlock(lock: ptl); |
1577 | } |
1578 | if (pmd_none(pmd: *pmd)) { |
1579 | addr = next; |
1580 | continue; |
1581 | } |
1582 | addr = zap_pte_range(tlb, vma, pmd, addr, end: next, details); |
1583 | if (addr != next) |
1584 | pmd--; |
1585 | } while (pmd++, cond_resched(), addr != end); |
1586 | |
1587 | return addr; |
1588 | } |
1589 | |
1590 | static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
1591 | struct vm_area_struct *vma, p4d_t *p4d, |
1592 | unsigned long addr, unsigned long end, |
1593 | struct zap_details *details) |
1594 | { |
1595 | pud_t *pud; |
1596 | unsigned long next; |
1597 | |
1598 | pud = pud_offset(p4d, address: addr); |
1599 | do { |
1600 | next = pud_addr_end(addr, end); |
1601 | if (pud_trans_huge(pud: *pud) || pud_devmap(pud: *pud)) { |
1602 | if (next - addr != HPAGE_PUD_SIZE) { |
1603 | mmap_assert_locked(mm: tlb->mm); |
1604 | split_huge_pud(vma, pud, addr); |
1605 | } else if (zap_huge_pud(tlb, vma, pud, addr)) |
1606 | goto next; |
1607 | /* fall through */ |
1608 | } |
1609 | if (pud_none_or_clear_bad(pud)) |
1610 | continue; |
1611 | next = zap_pmd_range(tlb, vma, pud, addr, end: next, details); |
1612 | next: |
1613 | cond_resched(); |
1614 | } while (pud++, addr = next, addr != end); |
1615 | |
1616 | return addr; |
1617 | } |
1618 | |
1619 | static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, |
1620 | struct vm_area_struct *vma, pgd_t *pgd, |
1621 | unsigned long addr, unsigned long end, |
1622 | struct zap_details *details) |
1623 | { |
1624 | p4d_t *p4d; |
1625 | unsigned long next; |
1626 | |
1627 | p4d = p4d_offset(pgd, address: addr); |
1628 | do { |
1629 | next = p4d_addr_end(addr, end); |
1630 | if (p4d_none_or_clear_bad(p4d)) |
1631 | continue; |
1632 | next = zap_pud_range(tlb, vma, p4d, addr, end: next, details); |
1633 | } while (p4d++, addr = next, addr != end); |
1634 | |
1635 | return addr; |
1636 | } |
1637 | |
1638 | void unmap_page_range(struct mmu_gather *tlb, |
1639 | struct vm_area_struct *vma, |
1640 | unsigned long addr, unsigned long end, |
1641 | struct zap_details *details) |
1642 | { |
1643 | pgd_t *pgd; |
1644 | unsigned long next; |
1645 | |
1646 | BUG_ON(addr >= end); |
1647 | tlb_start_vma(tlb, vma); |
1648 | pgd = pgd_offset(vma->vm_mm, addr); |
1649 | do { |
1650 | next = pgd_addr_end(addr, end); |
1651 | if (pgd_none_or_clear_bad(pgd)) |
1652 | continue; |
1653 | next = zap_p4d_range(tlb, vma, pgd, addr, end: next, details); |
1654 | } while (pgd++, addr = next, addr != end); |
1655 | tlb_end_vma(tlb, vma); |
1656 | } |
1657 | |
1658 | |
1659 | static void unmap_single_vma(struct mmu_gather *tlb, |
1660 | struct vm_area_struct *vma, unsigned long start_addr, |
1661 | unsigned long end_addr, |
1662 | struct zap_details *details, bool mm_wr_locked) |
1663 | { |
1664 | unsigned long start = max(vma->vm_start, start_addr); |
1665 | unsigned long end; |
1666 | |
1667 | if (start >= vma->vm_end) |
1668 | return; |
1669 | end = min(vma->vm_end, end_addr); |
1670 | if (end <= vma->vm_start) |
1671 | return; |
1672 | |
1673 | if (vma->vm_file) |
1674 | uprobe_munmap(vma, start, end); |
1675 | |
1676 | if (unlikely(vma->vm_flags & VM_PFNMAP)) |
1677 | untrack_pfn(vma, pfn: 0, size: 0, mm_wr_locked); |
1678 | |
1679 | if (start != end) { |
1680 | if (unlikely(is_vm_hugetlb_page(vma))) { |
1681 | /* |
1682 | * It is undesirable to test vma->vm_file as it |
1683 | * should be non-null for valid hugetlb area. |
1684 | * However, vm_file will be NULL in the error |
1685 | * cleanup path of mmap_region. When |
1686 | * hugetlbfs ->mmap method fails, |
1687 | * mmap_region() nullifies vma->vm_file |
1688 | * before calling this function to clean up. |
1689 | * Since no pte has actually been setup, it is |
1690 | * safe to do nothing in this case. |
1691 | */ |
1692 | if (vma->vm_file) { |
1693 | zap_flags_t zap_flags = details ? |
1694 | details->zap_flags : 0; |
1695 | __unmap_hugepage_range(tlb, vma, start, end, |
1696 | NULL, zap_flags); |
1697 | } |
1698 | } else |
1699 | unmap_page_range(tlb, vma, addr: start, end, details); |
1700 | } |
1701 | } |
1702 | |
1703 | /** |
1704 | * unmap_vmas - unmap a range of memory covered by a list of vma's |
1705 | * @tlb: address of the caller's struct mmu_gather |
1706 | * @mas: the maple state |
1707 | * @vma: the starting vma |
1708 | * @start_addr: virtual address at which to start unmapping |
1709 | * @end_addr: virtual address at which to end unmapping |
1710 | * @tree_end: The maximum index to check |
1711 | * @mm_wr_locked: lock flag |
1712 | * |
1713 | * Unmap all pages in the vma list. |
1714 | * |
1715 | * Only addresses between `start' and `end' will be unmapped. |
1716 | * |
1717 | * The VMA list must be sorted in ascending virtual address order. |
1718 | * |
1719 | * unmap_vmas() assumes that the caller will flush the whole unmapped address |
1720 | * range after unmap_vmas() returns. So the only responsibility here is to |
1721 | * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
1722 | * drops the lock and schedules. |
1723 | */ |
1724 | void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas, |
1725 | struct vm_area_struct *vma, unsigned long start_addr, |
1726 | unsigned long end_addr, unsigned long tree_end, |
1727 | bool mm_wr_locked) |
1728 | { |
1729 | struct mmu_notifier_range range; |
1730 | struct zap_details details = { |
1731 | .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP, |
1732 | /* Careful - we need to zap private pages too! */ |
1733 | .even_cows = true, |
1734 | }; |
1735 | |
1736 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_UNMAP, flags: 0, mm: vma->vm_mm, |
1737 | start: start_addr, end: end_addr); |
1738 | mmu_notifier_invalidate_range_start(range: &range); |
1739 | do { |
1740 | unsigned long start = start_addr; |
1741 | unsigned long end = end_addr; |
1742 | hugetlb_zap_begin(vma, start: &start, end: &end); |
1743 | unmap_single_vma(tlb, vma, start_addr: start, end_addr: end, details: &details, |
1744 | mm_wr_locked); |
1745 | hugetlb_zap_end(vma, details: &details); |
1746 | } while ((vma = mas_find(mas, max: tree_end - 1)) != NULL); |
1747 | mmu_notifier_invalidate_range_end(range: &range); |
1748 | } |
1749 | |
1750 | /** |
1751 | * zap_page_range_single - remove user pages in a given range |
1752 | * @vma: vm_area_struct holding the applicable pages |
1753 | * @address: starting address of pages to zap |
1754 | * @size: number of bytes to zap |
1755 | * @details: details of shared cache invalidation |
1756 | * |
1757 | * The range must fit into one VMA. |
1758 | */ |
1759 | void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, |
1760 | unsigned long size, struct zap_details *details) |
1761 | { |
1762 | const unsigned long end = address + size; |
1763 | struct mmu_notifier_range range; |
1764 | struct mmu_gather tlb; |
1765 | |
1766 | lru_add_drain(); |
1767 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_CLEAR, flags: 0, mm: vma->vm_mm, |
1768 | start: address, end); |
1769 | hugetlb_zap_begin(vma, start: &range.start, end: &range.end); |
1770 | tlb_gather_mmu(tlb: &tlb, mm: vma->vm_mm); |
1771 | update_hiwater_rss(mm: vma->vm_mm); |
1772 | mmu_notifier_invalidate_range_start(range: &range); |
1773 | /* |
1774 | * unmap 'address-end' not 'range.start-range.end' as range |
1775 | * could have been expanded for hugetlb pmd sharing. |
1776 | */ |
1777 | unmap_single_vma(tlb: &tlb, vma, start_addr: address, end_addr: end, details, mm_wr_locked: false); |
1778 | mmu_notifier_invalidate_range_end(range: &range); |
1779 | tlb_finish_mmu(tlb: &tlb); |
1780 | hugetlb_zap_end(vma, details); |
1781 | } |
1782 | |
1783 | /** |
1784 | * zap_vma_ptes - remove ptes mapping the vma |
1785 | * @vma: vm_area_struct holding ptes to be zapped |
1786 | * @address: starting address of pages to zap |
1787 | * @size: number of bytes to zap |
1788 | * |
1789 | * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
1790 | * |
1791 | * The entire address range must be fully contained within the vma. |
1792 | * |
1793 | */ |
1794 | void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
1795 | unsigned long size) |
1796 | { |
1797 | if (!range_in_vma(vma, start: address, end: address + size) || |
1798 | !(vma->vm_flags & VM_PFNMAP)) |
1799 | return; |
1800 | |
1801 | zap_page_range_single(vma, address, size, NULL); |
1802 | } |
1803 | EXPORT_SYMBOL_GPL(zap_vma_ptes); |
1804 | |
1805 | static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) |
1806 | { |
1807 | pgd_t *pgd; |
1808 | p4d_t *p4d; |
1809 | pud_t *pud; |
1810 | pmd_t *pmd; |
1811 | |
1812 | pgd = pgd_offset(mm, addr); |
1813 | p4d = p4d_alloc(mm, pgd, address: addr); |
1814 | if (!p4d) |
1815 | return NULL; |
1816 | pud = pud_alloc(mm, p4d, address: addr); |
1817 | if (!pud) |
1818 | return NULL; |
1819 | pmd = pmd_alloc(mm, pud, address: addr); |
1820 | if (!pmd) |
1821 | return NULL; |
1822 | |
1823 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
1824 | return pmd; |
1825 | } |
1826 | |
1827 | pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, |
1828 | spinlock_t **ptl) |
1829 | { |
1830 | pmd_t *pmd = walk_to_pmd(mm, addr); |
1831 | |
1832 | if (!pmd) |
1833 | return NULL; |
1834 | return pte_alloc_map_lock(mm, pmd, addr, ptl); |
1835 | } |
1836 | |
1837 | static int validate_page_before_insert(struct page *page) |
1838 | { |
1839 | if (PageAnon(page) || PageSlab(page) || page_has_type(page)) |
1840 | return -EINVAL; |
1841 | flush_dcache_page(page); |
1842 | return 0; |
1843 | } |
1844 | |
1845 | static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte, |
1846 | unsigned long addr, struct page *page, pgprot_t prot) |
1847 | { |
1848 | if (!pte_none(pte: ptep_get(ptep: pte))) |
1849 | return -EBUSY; |
1850 | /* Ok, finally just insert the thing.. */ |
1851 | get_page(page); |
1852 | inc_mm_counter(mm: vma->vm_mm, member: mm_counter_file(page)); |
1853 | page_add_file_rmap(page, vma, compound: false); |
1854 | set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot)); |
1855 | return 0; |
1856 | } |
1857 | |
1858 | /* |
1859 | * This is the old fallback for page remapping. |
1860 | * |
1861 | * For historical reasons, it only allows reserved pages. Only |
1862 | * old drivers should use this, and they needed to mark their |
1863 | * pages reserved for the old functions anyway. |
1864 | */ |
1865 | static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
1866 | struct page *page, pgprot_t prot) |
1867 | { |
1868 | int retval; |
1869 | pte_t *pte; |
1870 | spinlock_t *ptl; |
1871 | |
1872 | retval = validate_page_before_insert(page); |
1873 | if (retval) |
1874 | goto out; |
1875 | retval = -ENOMEM; |
1876 | pte = get_locked_pte(mm: vma->vm_mm, addr, ptl: &ptl); |
1877 | if (!pte) |
1878 | goto out; |
1879 | retval = insert_page_into_pte_locked(vma, pte, addr, page, prot); |
1880 | pte_unmap_unlock(pte, ptl); |
1881 | out: |
1882 | return retval; |
1883 | } |
1884 | |
1885 | static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte, |
1886 | unsigned long addr, struct page *page, pgprot_t prot) |
1887 | { |
1888 | int err; |
1889 | |
1890 | if (!page_count(page)) |
1891 | return -EINVAL; |
1892 | err = validate_page_before_insert(page); |
1893 | if (err) |
1894 | return err; |
1895 | return insert_page_into_pte_locked(vma, pte, addr, page, prot); |
1896 | } |
1897 | |
1898 | /* insert_pages() amortizes the cost of spinlock operations |
1899 | * when inserting pages in a loop. |
1900 | */ |
1901 | static int insert_pages(struct vm_area_struct *vma, unsigned long addr, |
1902 | struct page **pages, unsigned long *num, pgprot_t prot) |
1903 | { |
1904 | pmd_t *pmd = NULL; |
1905 | pte_t *start_pte, *pte; |
1906 | spinlock_t *pte_lock; |
1907 | struct mm_struct *const mm = vma->vm_mm; |
1908 | unsigned long curr_page_idx = 0; |
1909 | unsigned long remaining_pages_total = *num; |
1910 | unsigned long pages_to_write_in_pmd; |
1911 | int ret; |
1912 | more: |
1913 | ret = -EFAULT; |
1914 | pmd = walk_to_pmd(mm, addr); |
1915 | if (!pmd) |
1916 | goto out; |
1917 | |
1918 | pages_to_write_in_pmd = min_t(unsigned long, |
1919 | remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); |
1920 | |
1921 | /* Allocate the PTE if necessary; takes PMD lock once only. */ |
1922 | ret = -ENOMEM; |
1923 | if (pte_alloc(mm, pmd)) |
1924 | goto out; |
1925 | |
1926 | while (pages_to_write_in_pmd) { |
1927 | int pte_idx = 0; |
1928 | const int batch_size = min_t(int, pages_to_write_in_pmd, 8); |
1929 | |
1930 | start_pte = pte_offset_map_lock(mm, pmd, addr, ptlp: &pte_lock); |
1931 | if (!start_pte) { |
1932 | ret = -EFAULT; |
1933 | goto out; |
1934 | } |
1935 | for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { |
1936 | int err = insert_page_in_batch_locked(vma, pte, |
1937 | addr, page: pages[curr_page_idx], prot); |
1938 | if (unlikely(err)) { |
1939 | pte_unmap_unlock(start_pte, pte_lock); |
1940 | ret = err; |
1941 | remaining_pages_total -= pte_idx; |
1942 | goto out; |
1943 | } |
1944 | addr += PAGE_SIZE; |
1945 | ++curr_page_idx; |
1946 | } |
1947 | pte_unmap_unlock(start_pte, pte_lock); |
1948 | pages_to_write_in_pmd -= batch_size; |
1949 | remaining_pages_total -= batch_size; |
1950 | } |
1951 | if (remaining_pages_total) |
1952 | goto more; |
1953 | ret = 0; |
1954 | out: |
1955 | *num = remaining_pages_total; |
1956 | return ret; |
1957 | } |
1958 | |
1959 | /** |
1960 | * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. |
1961 | * @vma: user vma to map to |
1962 | * @addr: target start user address of these pages |
1963 | * @pages: source kernel pages |
1964 | * @num: in: number of pages to map. out: number of pages that were *not* |
1965 | * mapped. (0 means all pages were successfully mapped). |
1966 | * |
1967 | * Preferred over vm_insert_page() when inserting multiple pages. |
1968 | * |
1969 | * In case of error, we may have mapped a subset of the provided |
1970 | * pages. It is the caller's responsibility to account for this case. |
1971 | * |
1972 | * The same restrictions apply as in vm_insert_page(). |
1973 | */ |
1974 | int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, |
1975 | struct page **pages, unsigned long *num) |
1976 | { |
1977 | const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; |
1978 | |
1979 | if (addr < vma->vm_start || end_addr >= vma->vm_end) |
1980 | return -EFAULT; |
1981 | if (!(vma->vm_flags & VM_MIXEDMAP)) { |
1982 | BUG_ON(mmap_read_trylock(vma->vm_mm)); |
1983 | BUG_ON(vma->vm_flags & VM_PFNMAP); |
1984 | vm_flags_set(vma, VM_MIXEDMAP); |
1985 | } |
1986 | /* Defer page refcount checking till we're about to map that page. */ |
1987 | return insert_pages(vma, addr, pages, num, prot: vma->vm_page_prot); |
1988 | } |
1989 | EXPORT_SYMBOL(vm_insert_pages); |
1990 | |
1991 | /** |
1992 | * vm_insert_page - insert single page into user vma |
1993 | * @vma: user vma to map to |
1994 | * @addr: target user address of this page |
1995 | * @page: source kernel page |
1996 | * |
1997 | * This allows drivers to insert individual pages they've allocated |
1998 | * into a user vma. |
1999 | * |
2000 | * The page has to be a nice clean _individual_ kernel allocation. |
2001 | * If you allocate a compound page, you need to have marked it as |
2002 | * such (__GFP_COMP), or manually just split the page up yourself |
2003 | * (see split_page()). |
2004 | * |
2005 | * NOTE! Traditionally this was done with "remap_pfn_range()" which |
2006 | * took an arbitrary page protection parameter. This doesn't allow |
2007 | * that. Your vma protection will have to be set up correctly, which |
2008 | * means that if you want a shared writable mapping, you'd better |
2009 | * ask for a shared writable mapping! |
2010 | * |
2011 | * The page does not need to be reserved. |
2012 | * |
2013 | * Usually this function is called from f_op->mmap() handler |
2014 | * under mm->mmap_lock write-lock, so it can change vma->vm_flags. |
2015 | * Caller must set VM_MIXEDMAP on vma if it wants to call this |
2016 | * function from other places, for example from page-fault handler. |
2017 | * |
2018 | * Return: %0 on success, negative error code otherwise. |
2019 | */ |
2020 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
2021 | struct page *page) |
2022 | { |
2023 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2024 | return -EFAULT; |
2025 | if (!page_count(page)) |
2026 | return -EINVAL; |
2027 | if (!(vma->vm_flags & VM_MIXEDMAP)) { |
2028 | BUG_ON(mmap_read_trylock(vma->vm_mm)); |
2029 | BUG_ON(vma->vm_flags & VM_PFNMAP); |
2030 | vm_flags_set(vma, VM_MIXEDMAP); |
2031 | } |
2032 | return insert_page(vma, addr, page, prot: vma->vm_page_prot); |
2033 | } |
2034 | EXPORT_SYMBOL(vm_insert_page); |
2035 | |
2036 | /* |
2037 | * __vm_map_pages - maps range of kernel pages into user vma |
2038 | * @vma: user vma to map to |
2039 | * @pages: pointer to array of source kernel pages |
2040 | * @num: number of pages in page array |
2041 | * @offset: user's requested vm_pgoff |
2042 | * |
2043 | * This allows drivers to map range of kernel pages into a user vma. |
2044 | * |
2045 | * Return: 0 on success and error code otherwise. |
2046 | */ |
2047 | static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
2048 | unsigned long num, unsigned long offset) |
2049 | { |
2050 | unsigned long count = vma_pages(vma); |
2051 | unsigned long uaddr = vma->vm_start; |
2052 | int ret, i; |
2053 | |
2054 | /* Fail if the user requested offset is beyond the end of the object */ |
2055 | if (offset >= num) |
2056 | return -ENXIO; |
2057 | |
2058 | /* Fail if the user requested size exceeds available object size */ |
2059 | if (count > num - offset) |
2060 | return -ENXIO; |
2061 | |
2062 | for (i = 0; i < count; i++) { |
2063 | ret = vm_insert_page(vma, uaddr, pages[offset + i]); |
2064 | if (ret < 0) |
2065 | return ret; |
2066 | uaddr += PAGE_SIZE; |
2067 | } |
2068 | |
2069 | return 0; |
2070 | } |
2071 | |
2072 | /** |
2073 | * vm_map_pages - maps range of kernel pages starts with non zero offset |
2074 | * @vma: user vma to map to |
2075 | * @pages: pointer to array of source kernel pages |
2076 | * @num: number of pages in page array |
2077 | * |
2078 | * Maps an object consisting of @num pages, catering for the user's |
2079 | * requested vm_pgoff |
2080 | * |
2081 | * If we fail to insert any page into the vma, the function will return |
2082 | * immediately leaving any previously inserted pages present. Callers |
2083 | * from the mmap handler may immediately return the error as their caller |
2084 | * will destroy the vma, removing any successfully inserted pages. Other |
2085 | * callers should make their own arrangements for calling unmap_region(). |
2086 | * |
2087 | * Context: Process context. Called by mmap handlers. |
2088 | * Return: 0 on success and error code otherwise. |
2089 | */ |
2090 | int vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
2091 | unsigned long num) |
2092 | { |
2093 | return __vm_map_pages(vma, pages, num, offset: vma->vm_pgoff); |
2094 | } |
2095 | EXPORT_SYMBOL(vm_map_pages); |
2096 | |
2097 | /** |
2098 | * vm_map_pages_zero - map range of kernel pages starts with zero offset |
2099 | * @vma: user vma to map to |
2100 | * @pages: pointer to array of source kernel pages |
2101 | * @num: number of pages in page array |
2102 | * |
2103 | * Similar to vm_map_pages(), except that it explicitly sets the offset |
2104 | * to 0. This function is intended for the drivers that did not consider |
2105 | * vm_pgoff. |
2106 | * |
2107 | * Context: Process context. Called by mmap handlers. |
2108 | * Return: 0 on success and error code otherwise. |
2109 | */ |
2110 | int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, |
2111 | unsigned long num) |
2112 | { |
2113 | return __vm_map_pages(vma, pages, num, offset: 0); |
2114 | } |
2115 | EXPORT_SYMBOL(vm_map_pages_zero); |
2116 | |
2117 | static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
2118 | pfn_t pfn, pgprot_t prot, bool mkwrite) |
2119 | { |
2120 | struct mm_struct *mm = vma->vm_mm; |
2121 | pte_t *pte, entry; |
2122 | spinlock_t *ptl; |
2123 | |
2124 | pte = get_locked_pte(mm, addr, ptl: &ptl); |
2125 | if (!pte) |
2126 | return VM_FAULT_OOM; |
2127 | entry = ptep_get(ptep: pte); |
2128 | if (!pte_none(pte: entry)) { |
2129 | if (mkwrite) { |
2130 | /* |
2131 | * For read faults on private mappings the PFN passed |
2132 | * in may not match the PFN we have mapped if the |
2133 | * mapped PFN is a writeable COW page. In the mkwrite |
2134 | * case we are creating a writable PTE for a shared |
2135 | * mapping and we expect the PFNs to match. If they |
2136 | * don't match, we are likely racing with block |
2137 | * allocation and mapping invalidation so just skip the |
2138 | * update. |
2139 | */ |
2140 | if (pte_pfn(pte: entry) != pfn_t_to_pfn(pfn)) { |
2141 | WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry))); |
2142 | goto out_unlock; |
2143 | } |
2144 | entry = pte_mkyoung(pte: entry); |
2145 | entry = maybe_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
2146 | if (ptep_set_access_flags(vma, address: addr, ptep: pte, entry, dirty: 1)) |
2147 | update_mmu_cache(vma, addr, ptep: pte); |
2148 | } |
2149 | goto out_unlock; |
2150 | } |
2151 | |
2152 | /* Ok, finally just insert the thing.. */ |
2153 | if (pfn_t_devmap(pfn)) |
2154 | entry = pte_mkdevmap(pte: pfn_t_pte(pfn, pgprot: prot)); |
2155 | else |
2156 | entry = pte_mkspecial(pte: pfn_t_pte(pfn, pgprot: prot)); |
2157 | |
2158 | if (mkwrite) { |
2159 | entry = pte_mkyoung(pte: entry); |
2160 | entry = maybe_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
2161 | } |
2162 | |
2163 | set_pte_at(mm, addr, pte, entry); |
2164 | update_mmu_cache(vma, addr, ptep: pte); /* XXX: why not for insert_page? */ |
2165 | |
2166 | out_unlock: |
2167 | pte_unmap_unlock(pte, ptl); |
2168 | return VM_FAULT_NOPAGE; |
2169 | } |
2170 | |
2171 | /** |
2172 | * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot |
2173 | * @vma: user vma to map to |
2174 | * @addr: target user address of this page |
2175 | * @pfn: source kernel pfn |
2176 | * @pgprot: pgprot flags for the inserted page |
2177 | * |
2178 | * This is exactly like vmf_insert_pfn(), except that it allows drivers |
2179 | * to override pgprot on a per-page basis. |
2180 | * |
2181 | * This only makes sense for IO mappings, and it makes no sense for |
2182 | * COW mappings. In general, using multiple vmas is preferable; |
2183 | * vmf_insert_pfn_prot should only be used if using multiple VMAs is |
2184 | * impractical. |
2185 | * |
2186 | * pgprot typically only differs from @vma->vm_page_prot when drivers set |
2187 | * caching- and encryption bits different than those of @vma->vm_page_prot, |
2188 | * because the caching- or encryption mode may not be known at mmap() time. |
2189 | * |
2190 | * This is ok as long as @vma->vm_page_prot is not used by the core vm |
2191 | * to set caching and encryption bits for those vmas (except for COW pages). |
2192 | * This is ensured by core vm only modifying these page table entries using |
2193 | * functions that don't touch caching- or encryption bits, using pte_modify() |
2194 | * if needed. (See for example mprotect()). |
2195 | * |
2196 | * Also when new page-table entries are created, this is only done using the |
2197 | * fault() callback, and never using the value of vma->vm_page_prot, |
2198 | * except for page-table entries that point to anonymous pages as the result |
2199 | * of COW. |
2200 | * |
2201 | * Context: Process context. May allocate using %GFP_KERNEL. |
2202 | * Return: vm_fault_t value. |
2203 | */ |
2204 | vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, |
2205 | unsigned long pfn, pgprot_t pgprot) |
2206 | { |
2207 | /* |
2208 | * Technically, architectures with pte_special can avoid all these |
2209 | * restrictions (same for remap_pfn_range). However we would like |
2210 | * consistency in testing and feature parity among all, so we should |
2211 | * try to keep these invariants in place for everybody. |
2212 | */ |
2213 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
2214 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
2215 | (VM_PFNMAP|VM_MIXEDMAP)); |
2216 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
2217 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
2218 | |
2219 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2220 | return VM_FAULT_SIGBUS; |
2221 | |
2222 | if (!pfn_modify_allowed(pfn, prot: pgprot)) |
2223 | return VM_FAULT_SIGBUS; |
2224 | |
2225 | track_pfn_insert(vma, prot: &pgprot, pfn: __pfn_to_pfn_t(pfn, PFN_DEV)); |
2226 | |
2227 | return insert_pfn(vma, addr, pfn: __pfn_to_pfn_t(pfn, PFN_DEV), prot: pgprot, |
2228 | mkwrite: false); |
2229 | } |
2230 | EXPORT_SYMBOL(vmf_insert_pfn_prot); |
2231 | |
2232 | /** |
2233 | * vmf_insert_pfn - insert single pfn into user vma |
2234 | * @vma: user vma to map to |
2235 | * @addr: target user address of this page |
2236 | * @pfn: source kernel pfn |
2237 | * |
2238 | * Similar to vm_insert_page, this allows drivers to insert individual pages |
2239 | * they've allocated into a user vma. Same comments apply. |
2240 | * |
2241 | * This function should only be called from a vm_ops->fault handler, and |
2242 | * in that case the handler should return the result of this function. |
2243 | * |
2244 | * vma cannot be a COW mapping. |
2245 | * |
2246 | * As this is called only for pages that do not currently exist, we |
2247 | * do not need to flush old virtual caches or the TLB. |
2248 | * |
2249 | * Context: Process context. May allocate using %GFP_KERNEL. |
2250 | * Return: vm_fault_t value. |
2251 | */ |
2252 | vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
2253 | unsigned long pfn) |
2254 | { |
2255 | return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); |
2256 | } |
2257 | EXPORT_SYMBOL(vmf_insert_pfn); |
2258 | |
2259 | static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) |
2260 | { |
2261 | /* these checks mirror the abort conditions in vm_normal_page */ |
2262 | if (vma->vm_flags & VM_MIXEDMAP) |
2263 | return true; |
2264 | if (pfn_t_devmap(pfn)) |
2265 | return true; |
2266 | if (pfn_t_special(pfn)) |
2267 | return true; |
2268 | if (is_zero_pfn(pfn: pfn_t_to_pfn(pfn))) |
2269 | return true; |
2270 | return false; |
2271 | } |
2272 | |
2273 | static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, |
2274 | unsigned long addr, pfn_t pfn, bool mkwrite) |
2275 | { |
2276 | pgprot_t pgprot = vma->vm_page_prot; |
2277 | int err; |
2278 | |
2279 | BUG_ON(!vm_mixed_ok(vma, pfn)); |
2280 | |
2281 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2282 | return VM_FAULT_SIGBUS; |
2283 | |
2284 | track_pfn_insert(vma, prot: &pgprot, pfn); |
2285 | |
2286 | if (!pfn_modify_allowed(pfn: pfn_t_to_pfn(pfn), prot: pgprot)) |
2287 | return VM_FAULT_SIGBUS; |
2288 | |
2289 | /* |
2290 | * If we don't have pte special, then we have to use the pfn_valid() |
2291 | * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
2292 | * refcount the page if pfn_valid is true (hence insert_page rather |
2293 | * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
2294 | * without pte special, it would there be refcounted as a normal page. |
2295 | */ |
2296 | if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && |
2297 | !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { |
2298 | struct page *page; |
2299 | |
2300 | /* |
2301 | * At this point we are committed to insert_page() |
2302 | * regardless of whether the caller specified flags that |
2303 | * result in pfn_t_has_page() == false. |
2304 | */ |
2305 | page = pfn_to_page(pfn_t_to_pfn(pfn)); |
2306 | err = insert_page(vma, addr, page, prot: pgprot); |
2307 | } else { |
2308 | return insert_pfn(vma, addr, pfn, prot: pgprot, mkwrite); |
2309 | } |
2310 | |
2311 | if (err == -ENOMEM) |
2312 | return VM_FAULT_OOM; |
2313 | if (err < 0 && err != -EBUSY) |
2314 | return VM_FAULT_SIGBUS; |
2315 | |
2316 | return VM_FAULT_NOPAGE; |
2317 | } |
2318 | |
2319 | vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
2320 | pfn_t pfn) |
2321 | { |
2322 | return __vm_insert_mixed(vma, addr, pfn, mkwrite: false); |
2323 | } |
2324 | EXPORT_SYMBOL(vmf_insert_mixed); |
2325 | |
2326 | /* |
2327 | * If the insertion of PTE failed because someone else already added a |
2328 | * different entry in the mean time, we treat that as success as we assume |
2329 | * the same entry was actually inserted. |
2330 | */ |
2331 | vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, |
2332 | unsigned long addr, pfn_t pfn) |
2333 | { |
2334 | return __vm_insert_mixed(vma, addr, pfn, mkwrite: true); |
2335 | } |
2336 | EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); |
2337 | |
2338 | /* |
2339 | * maps a range of physical memory into the requested pages. the old |
2340 | * mappings are removed. any references to nonexistent pages results |
2341 | * in null mappings (currently treated as "copy-on-access") |
2342 | */ |
2343 | static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
2344 | unsigned long addr, unsigned long end, |
2345 | unsigned long pfn, pgprot_t prot) |
2346 | { |
2347 | pte_t *pte, *mapped_pte; |
2348 | spinlock_t *ptl; |
2349 | int err = 0; |
2350 | |
2351 | mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
2352 | if (!pte) |
2353 | return -ENOMEM; |
2354 | arch_enter_lazy_mmu_mode(); |
2355 | do { |
2356 | BUG_ON(!pte_none(ptep_get(pte))); |
2357 | if (!pfn_modify_allowed(pfn, prot)) { |
2358 | err = -EACCES; |
2359 | break; |
2360 | } |
2361 | set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
2362 | pfn++; |
2363 | } while (pte++, addr += PAGE_SIZE, addr != end); |
2364 | arch_leave_lazy_mmu_mode(); |
2365 | pte_unmap_unlock(mapped_pte, ptl); |
2366 | return err; |
2367 | } |
2368 | |
2369 | static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
2370 | unsigned long addr, unsigned long end, |
2371 | unsigned long pfn, pgprot_t prot) |
2372 | { |
2373 | pmd_t *pmd; |
2374 | unsigned long next; |
2375 | int err; |
2376 | |
2377 | pfn -= addr >> PAGE_SHIFT; |
2378 | pmd = pmd_alloc(mm, pud, address: addr); |
2379 | if (!pmd) |
2380 | return -ENOMEM; |
2381 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
2382 | do { |
2383 | next = pmd_addr_end(addr, end); |
2384 | err = remap_pte_range(mm, pmd, addr, end: next, |
2385 | pfn: pfn + (addr >> PAGE_SHIFT), prot); |
2386 | if (err) |
2387 | return err; |
2388 | } while (pmd++, addr = next, addr != end); |
2389 | return 0; |
2390 | } |
2391 | |
2392 | static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, |
2393 | unsigned long addr, unsigned long end, |
2394 | unsigned long pfn, pgprot_t prot) |
2395 | { |
2396 | pud_t *pud; |
2397 | unsigned long next; |
2398 | int err; |
2399 | |
2400 | pfn -= addr >> PAGE_SHIFT; |
2401 | pud = pud_alloc(mm, p4d, address: addr); |
2402 | if (!pud) |
2403 | return -ENOMEM; |
2404 | do { |
2405 | next = pud_addr_end(addr, end); |
2406 | err = remap_pmd_range(mm, pud, addr, end: next, |
2407 | pfn: pfn + (addr >> PAGE_SHIFT), prot); |
2408 | if (err) |
2409 | return err; |
2410 | } while (pud++, addr = next, addr != end); |
2411 | return 0; |
2412 | } |
2413 | |
2414 | static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
2415 | unsigned long addr, unsigned long end, |
2416 | unsigned long pfn, pgprot_t prot) |
2417 | { |
2418 | p4d_t *p4d; |
2419 | unsigned long next; |
2420 | int err; |
2421 | |
2422 | pfn -= addr >> PAGE_SHIFT; |
2423 | p4d = p4d_alloc(mm, pgd, address: addr); |
2424 | if (!p4d) |
2425 | return -ENOMEM; |
2426 | do { |
2427 | next = p4d_addr_end(addr, end); |
2428 | err = remap_pud_range(mm, p4d, addr, end: next, |
2429 | pfn: pfn + (addr >> PAGE_SHIFT), prot); |
2430 | if (err) |
2431 | return err; |
2432 | } while (p4d++, addr = next, addr != end); |
2433 | return 0; |
2434 | } |
2435 | |
2436 | /* |
2437 | * Variant of remap_pfn_range that does not call track_pfn_remap. The caller |
2438 | * must have pre-validated the caching bits of the pgprot_t. |
2439 | */ |
2440 | int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, |
2441 | unsigned long pfn, unsigned long size, pgprot_t prot) |
2442 | { |
2443 | pgd_t *pgd; |
2444 | unsigned long next; |
2445 | unsigned long end = addr + PAGE_ALIGN(size); |
2446 | struct mm_struct *mm = vma->vm_mm; |
2447 | int err; |
2448 | |
2449 | if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) |
2450 | return -EINVAL; |
2451 | |
2452 | /* |
2453 | * Physically remapped pages are special. Tell the |
2454 | * rest of the world about it: |
2455 | * VM_IO tells people not to look at these pages |
2456 | * (accesses can have side effects). |
2457 | * VM_PFNMAP tells the core MM that the base pages are just |
2458 | * raw PFN mappings, and do not have a "struct page" associated |
2459 | * with them. |
2460 | * VM_DONTEXPAND |
2461 | * Disable vma merging and expanding with mremap(). |
2462 | * VM_DONTDUMP |
2463 | * Omit vma from core dump, even when VM_IO turned off. |
2464 | * |
2465 | * There's a horrible special case to handle copy-on-write |
2466 | * behaviour that some programs depend on. We mark the "original" |
2467 | * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
2468 | * See vm_normal_page() for details. |
2469 | */ |
2470 | if (is_cow_mapping(flags: vma->vm_flags)) { |
2471 | if (addr != vma->vm_start || end != vma->vm_end) |
2472 | return -EINVAL; |
2473 | vma->vm_pgoff = pfn; |
2474 | } |
2475 | |
2476 | vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); |
2477 | |
2478 | BUG_ON(addr >= end); |
2479 | pfn -= addr >> PAGE_SHIFT; |
2480 | pgd = pgd_offset(mm, addr); |
2481 | flush_cache_range(vma, start: addr, end); |
2482 | do { |
2483 | next = pgd_addr_end(addr, end); |
2484 | err = remap_p4d_range(mm, pgd, addr, end: next, |
2485 | pfn: pfn + (addr >> PAGE_SHIFT), prot); |
2486 | if (err) |
2487 | return err; |
2488 | } while (pgd++, addr = next, addr != end); |
2489 | |
2490 | return 0; |
2491 | } |
2492 | |
2493 | /** |
2494 | * remap_pfn_range - remap kernel memory to userspace |
2495 | * @vma: user vma to map to |
2496 | * @addr: target page aligned user address to start at |
2497 | * @pfn: page frame number of kernel physical memory address |
2498 | * @size: size of mapping area |
2499 | * @prot: page protection flags for this mapping |
2500 | * |
2501 | * Note: this is only safe if the mm semaphore is held when called. |
2502 | * |
2503 | * Return: %0 on success, negative error code otherwise. |
2504 | */ |
2505 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
2506 | unsigned long pfn, unsigned long size, pgprot_t prot) |
2507 | { |
2508 | int err; |
2509 | |
2510 | err = track_pfn_remap(vma, prot: &prot, pfn, addr, PAGE_ALIGN(size)); |
2511 | if (err) |
2512 | return -EINVAL; |
2513 | |
2514 | err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); |
2515 | if (err) |
2516 | untrack_pfn(vma, pfn, PAGE_ALIGN(size), mm_wr_locked: true); |
2517 | return err; |
2518 | } |
2519 | EXPORT_SYMBOL(remap_pfn_range); |
2520 | |
2521 | /** |
2522 | * vm_iomap_memory - remap memory to userspace |
2523 | * @vma: user vma to map to |
2524 | * @start: start of the physical memory to be mapped |
2525 | * @len: size of area |
2526 | * |
2527 | * This is a simplified io_remap_pfn_range() for common driver use. The |
2528 | * driver just needs to give us the physical memory range to be mapped, |
2529 | * we'll figure out the rest from the vma information. |
2530 | * |
2531 | * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get |
2532 | * whatever write-combining details or similar. |
2533 | * |
2534 | * Return: %0 on success, negative error code otherwise. |
2535 | */ |
2536 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
2537 | { |
2538 | unsigned long vm_len, pfn, pages; |
2539 | |
2540 | /* Check that the physical memory area passed in looks valid */ |
2541 | if (start + len < start) |
2542 | return -EINVAL; |
2543 | /* |
2544 | * You *really* shouldn't map things that aren't page-aligned, |
2545 | * but we've historically allowed it because IO memory might |
2546 | * just have smaller alignment. |
2547 | */ |
2548 | len += start & ~PAGE_MASK; |
2549 | pfn = start >> PAGE_SHIFT; |
2550 | pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; |
2551 | if (pfn + pages < pfn) |
2552 | return -EINVAL; |
2553 | |
2554 | /* We start the mapping 'vm_pgoff' pages into the area */ |
2555 | if (vma->vm_pgoff > pages) |
2556 | return -EINVAL; |
2557 | pfn += vma->vm_pgoff; |
2558 | pages -= vma->vm_pgoff; |
2559 | |
2560 | /* Can we fit all of the mapping? */ |
2561 | vm_len = vma->vm_end - vma->vm_start; |
2562 | if (vm_len >> PAGE_SHIFT > pages) |
2563 | return -EINVAL; |
2564 | |
2565 | /* Ok, let it rip */ |
2566 | return io_remap_pfn_range(vma, addr: vma->vm_start, pfn, size: vm_len, prot: vma->vm_page_prot); |
2567 | } |
2568 | EXPORT_SYMBOL(vm_iomap_memory); |
2569 | |
2570 | static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
2571 | unsigned long addr, unsigned long end, |
2572 | pte_fn_t fn, void *data, bool create, |
2573 | pgtbl_mod_mask *mask) |
2574 | { |
2575 | pte_t *pte, *mapped_pte; |
2576 | int err = 0; |
2577 | spinlock_t *ptl; |
2578 | |
2579 | if (create) { |
2580 | mapped_pte = pte = (mm == &init_mm) ? |
2581 | pte_alloc_kernel_track(pmd, addr, mask) : |
2582 | pte_alloc_map_lock(mm, pmd, addr, &ptl); |
2583 | if (!pte) |
2584 | return -ENOMEM; |
2585 | } else { |
2586 | mapped_pte = pte = (mm == &init_mm) ? |
2587 | pte_offset_kernel(pmd, address: addr) : |
2588 | pte_offset_map_lock(mm, pmd, addr, ptlp: &ptl); |
2589 | if (!pte) |
2590 | return -EINVAL; |
2591 | } |
2592 | |
2593 | arch_enter_lazy_mmu_mode(); |
2594 | |
2595 | if (fn) { |
2596 | do { |
2597 | if (create || !pte_none(pte: ptep_get(ptep: pte))) { |
2598 | err = fn(pte++, addr, data); |
2599 | if (err) |
2600 | break; |
2601 | } |
2602 | } while (addr += PAGE_SIZE, addr != end); |
2603 | } |
2604 | *mask |= PGTBL_PTE_MODIFIED; |
2605 | |
2606 | arch_leave_lazy_mmu_mode(); |
2607 | |
2608 | if (mm != &init_mm) |
2609 | pte_unmap_unlock(mapped_pte, ptl); |
2610 | return err; |
2611 | } |
2612 | |
2613 | static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
2614 | unsigned long addr, unsigned long end, |
2615 | pte_fn_t fn, void *data, bool create, |
2616 | pgtbl_mod_mask *mask) |
2617 | { |
2618 | pmd_t *pmd; |
2619 | unsigned long next; |
2620 | int err = 0; |
2621 | |
2622 | BUG_ON(pud_huge(*pud)); |
2623 | |
2624 | if (create) { |
2625 | pmd = pmd_alloc_track(mm, pud, address: addr, mod_mask: mask); |
2626 | if (!pmd) |
2627 | return -ENOMEM; |
2628 | } else { |
2629 | pmd = pmd_offset(pud, address: addr); |
2630 | } |
2631 | do { |
2632 | next = pmd_addr_end(addr, end); |
2633 | if (pmd_none(pmd: *pmd) && !create) |
2634 | continue; |
2635 | if (WARN_ON_ONCE(pmd_leaf(*pmd))) |
2636 | return -EINVAL; |
2637 | if (!pmd_none(pmd: *pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { |
2638 | if (!create) |
2639 | continue; |
2640 | pmd_clear_bad(pmd); |
2641 | } |
2642 | err = apply_to_pte_range(mm, pmd, addr, end: next, |
2643 | fn, data, create, mask); |
2644 | if (err) |
2645 | break; |
2646 | } while (pmd++, addr = next, addr != end); |
2647 | |
2648 | return err; |
2649 | } |
2650 | |
2651 | static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, |
2652 | unsigned long addr, unsigned long end, |
2653 | pte_fn_t fn, void *data, bool create, |
2654 | pgtbl_mod_mask *mask) |
2655 | { |
2656 | pud_t *pud; |
2657 | unsigned long next; |
2658 | int err = 0; |
2659 | |
2660 | if (create) { |
2661 | pud = pud_alloc_track(mm, p4d, address: addr, mod_mask: mask); |
2662 | if (!pud) |
2663 | return -ENOMEM; |
2664 | } else { |
2665 | pud = pud_offset(p4d, address: addr); |
2666 | } |
2667 | do { |
2668 | next = pud_addr_end(addr, end); |
2669 | if (pud_none(pud: *pud) && !create) |
2670 | continue; |
2671 | if (WARN_ON_ONCE(pud_leaf(*pud))) |
2672 | return -EINVAL; |
2673 | if (!pud_none(pud: *pud) && WARN_ON_ONCE(pud_bad(*pud))) { |
2674 | if (!create) |
2675 | continue; |
2676 | pud_clear_bad(pud); |
2677 | } |
2678 | err = apply_to_pmd_range(mm, pud, addr, end: next, |
2679 | fn, data, create, mask); |
2680 | if (err) |
2681 | break; |
2682 | } while (pud++, addr = next, addr != end); |
2683 | |
2684 | return err; |
2685 | } |
2686 | |
2687 | static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
2688 | unsigned long addr, unsigned long end, |
2689 | pte_fn_t fn, void *data, bool create, |
2690 | pgtbl_mod_mask *mask) |
2691 | { |
2692 | p4d_t *p4d; |
2693 | unsigned long next; |
2694 | int err = 0; |
2695 | |
2696 | if (create) { |
2697 | p4d = p4d_alloc_track(mm, pgd, address: addr, mod_mask: mask); |
2698 | if (!p4d) |
2699 | return -ENOMEM; |
2700 | } else { |
2701 | p4d = p4d_offset(pgd, address: addr); |
2702 | } |
2703 | do { |
2704 | next = p4d_addr_end(addr, end); |
2705 | if (p4d_none(p4d: *p4d) && !create) |
2706 | continue; |
2707 | if (WARN_ON_ONCE(p4d_leaf(*p4d))) |
2708 | return -EINVAL; |
2709 | if (!p4d_none(p4d: *p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { |
2710 | if (!create) |
2711 | continue; |
2712 | p4d_clear_bad(p4d); |
2713 | } |
2714 | err = apply_to_pud_range(mm, p4d, addr, end: next, |
2715 | fn, data, create, mask); |
2716 | if (err) |
2717 | break; |
2718 | } while (p4d++, addr = next, addr != end); |
2719 | |
2720 | return err; |
2721 | } |
2722 | |
2723 | static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
2724 | unsigned long size, pte_fn_t fn, |
2725 | void *data, bool create) |
2726 | { |
2727 | pgd_t *pgd; |
2728 | unsigned long start = addr, next; |
2729 | unsigned long end = addr + size; |
2730 | pgtbl_mod_mask mask = 0; |
2731 | int err = 0; |
2732 | |
2733 | if (WARN_ON(addr >= end)) |
2734 | return -EINVAL; |
2735 | |
2736 | pgd = pgd_offset(mm, addr); |
2737 | do { |
2738 | next = pgd_addr_end(addr, end); |
2739 | if (pgd_none(pgd: *pgd) && !create) |
2740 | continue; |
2741 | if (WARN_ON_ONCE(pgd_leaf(*pgd))) |
2742 | return -EINVAL; |
2743 | if (!pgd_none(pgd: *pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { |
2744 | if (!create) |
2745 | continue; |
2746 | pgd_clear_bad(pgd); |
2747 | } |
2748 | err = apply_to_p4d_range(mm, pgd, addr, end: next, |
2749 | fn, data, create, mask: &mask); |
2750 | if (err) |
2751 | break; |
2752 | } while (pgd++, addr = next, addr != end); |
2753 | |
2754 | if (mask & ARCH_PAGE_TABLE_SYNC_MASK) |
2755 | arch_sync_kernel_mappings(start, end: start + size); |
2756 | |
2757 | return err; |
2758 | } |
2759 | |
2760 | /* |
2761 | * Scan a region of virtual memory, filling in page tables as necessary |
2762 | * and calling a provided function on each leaf page table. |
2763 | */ |
2764 | int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
2765 | unsigned long size, pte_fn_t fn, void *data) |
2766 | { |
2767 | return __apply_to_page_range(mm, addr, size, fn, data, create: true); |
2768 | } |
2769 | EXPORT_SYMBOL_GPL(apply_to_page_range); |
2770 | |
2771 | /* |
2772 | * Scan a region of virtual memory, calling a provided function on |
2773 | * each leaf page table where it exists. |
2774 | * |
2775 | * Unlike apply_to_page_range, this does _not_ fill in page tables |
2776 | * where they are absent. |
2777 | */ |
2778 | int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr, |
2779 | unsigned long size, pte_fn_t fn, void *data) |
2780 | { |
2781 | return __apply_to_page_range(mm, addr, size, fn, data, create: false); |
2782 | } |
2783 | EXPORT_SYMBOL_GPL(apply_to_existing_page_range); |
2784 | |
2785 | /* |
2786 | * handle_pte_fault chooses page fault handler according to an entry which was |
2787 | * read non-atomically. Before making any commitment, on those architectures |
2788 | * or configurations (e.g. i386 with PAE) which might give a mix of unmatched |
2789 | * parts, do_swap_page must check under lock before unmapping the pte and |
2790 | * proceeding (but do_wp_page is only called after already making such a check; |
2791 | * and do_anonymous_page can safely check later on). |
2792 | */ |
2793 | static inline int pte_unmap_same(struct vm_fault *vmf) |
2794 | { |
2795 | int same = 1; |
2796 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION) |
2797 | if (sizeof(pte_t) > sizeof(unsigned long)) { |
2798 | spin_lock(lock: vmf->ptl); |
2799 | same = pte_same(a: ptep_get(ptep: vmf->pte), b: vmf->orig_pte); |
2800 | spin_unlock(lock: vmf->ptl); |
2801 | } |
2802 | #endif |
2803 | pte_unmap(pte: vmf->pte); |
2804 | vmf->pte = NULL; |
2805 | return same; |
2806 | } |
2807 | |
2808 | /* |
2809 | * Return: |
2810 | * 0: copied succeeded |
2811 | * -EHWPOISON: copy failed due to hwpoison in source page |
2812 | * -EAGAIN: copied failed (some other reason) |
2813 | */ |
2814 | static inline int __wp_page_copy_user(struct page *dst, struct page *src, |
2815 | struct vm_fault *vmf) |
2816 | { |
2817 | int ret; |
2818 | void *kaddr; |
2819 | void __user *uaddr; |
2820 | struct vm_area_struct *vma = vmf->vma; |
2821 | struct mm_struct *mm = vma->vm_mm; |
2822 | unsigned long addr = vmf->address; |
2823 | |
2824 | if (likely(src)) { |
2825 | if (copy_mc_user_highpage(to: dst, from: src, vaddr: addr, vma)) { |
2826 | memory_failure_queue(page_to_pfn(src), flags: 0); |
2827 | return -EHWPOISON; |
2828 | } |
2829 | return 0; |
2830 | } |
2831 | |
2832 | /* |
2833 | * If the source page was a PFN mapping, we don't have |
2834 | * a "struct page" for it. We do a best-effort copy by |
2835 | * just copying from the original user address. If that |
2836 | * fails, we just zero-fill it. Live with it. |
2837 | */ |
2838 | kaddr = kmap_atomic(page: dst); |
2839 | uaddr = (void __user *)(addr & PAGE_MASK); |
2840 | |
2841 | /* |
2842 | * On architectures with software "accessed" bits, we would |
2843 | * take a double page fault, so mark it accessed here. |
2844 | */ |
2845 | vmf->pte = NULL; |
2846 | if (!arch_has_hw_pte_young() && !pte_young(pte: vmf->orig_pte)) { |
2847 | pte_t entry; |
2848 | |
2849 | vmf->pte = pte_offset_map_lock(mm, pmd: vmf->pmd, addr, ptlp: &vmf->ptl); |
2850 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
2851 | /* |
2852 | * Other thread has already handled the fault |
2853 | * and update local tlb only |
2854 | */ |
2855 | if (vmf->pte) |
2856 | update_mmu_tlb(vma, address: addr, ptep: vmf->pte); |
2857 | ret = -EAGAIN; |
2858 | goto pte_unlock; |
2859 | } |
2860 | |
2861 | entry = pte_mkyoung(pte: vmf->orig_pte); |
2862 | if (ptep_set_access_flags(vma, address: addr, ptep: vmf->pte, entry, dirty: 0)) |
2863 | update_mmu_cache_range(vmf, vma, addr, ptep: vmf->pte, nr: 1); |
2864 | } |
2865 | |
2866 | /* |
2867 | * This really shouldn't fail, because the page is there |
2868 | * in the page tables. But it might just be unreadable, |
2869 | * in which case we just give up and fill the result with |
2870 | * zeroes. |
2871 | */ |
2872 | if (__copy_from_user_inatomic(to: kaddr, from: uaddr, PAGE_SIZE)) { |
2873 | if (vmf->pte) |
2874 | goto warn; |
2875 | |
2876 | /* Re-validate under PTL if the page is still mapped */ |
2877 | vmf->pte = pte_offset_map_lock(mm, pmd: vmf->pmd, addr, ptlp: &vmf->ptl); |
2878 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
2879 | /* The PTE changed under us, update local tlb */ |
2880 | if (vmf->pte) |
2881 | update_mmu_tlb(vma, address: addr, ptep: vmf->pte); |
2882 | ret = -EAGAIN; |
2883 | goto pte_unlock; |
2884 | } |
2885 | |
2886 | /* |
2887 | * The same page can be mapped back since last copy attempt. |
2888 | * Try to copy again under PTL. |
2889 | */ |
2890 | if (__copy_from_user_inatomic(to: kaddr, from: uaddr, PAGE_SIZE)) { |
2891 | /* |
2892 | * Give a warn in case there can be some obscure |
2893 | * use-case |
2894 | */ |
2895 | warn: |
2896 | WARN_ON_ONCE(1); |
2897 | clear_page(page: kaddr); |
2898 | } |
2899 | } |
2900 | |
2901 | ret = 0; |
2902 | |
2903 | pte_unlock: |
2904 | if (vmf->pte) |
2905 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
2906 | kunmap_atomic(kaddr); |
2907 | flush_dcache_page(page: dst); |
2908 | |
2909 | return ret; |
2910 | } |
2911 | |
2912 | static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) |
2913 | { |
2914 | struct file *vm_file = vma->vm_file; |
2915 | |
2916 | if (vm_file) |
2917 | return mapping_gfp_mask(mapping: vm_file->f_mapping) | __GFP_FS | __GFP_IO; |
2918 | |
2919 | /* |
2920 | * Special mappings (e.g. VDSO) do not have any file so fake |
2921 | * a default GFP_KERNEL for them. |
2922 | */ |
2923 | return GFP_KERNEL; |
2924 | } |
2925 | |
2926 | /* |
2927 | * Notify the address space that the page is about to become writable so that |
2928 | * it can prohibit this or wait for the page to get into an appropriate state. |
2929 | * |
2930 | * We do this without the lock held, so that it can sleep if it needs to. |
2931 | */ |
2932 | static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio) |
2933 | { |
2934 | vm_fault_t ret; |
2935 | unsigned int old_flags = vmf->flags; |
2936 | |
2937 | vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
2938 | |
2939 | if (vmf->vma->vm_file && |
2940 | IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host)) |
2941 | return VM_FAULT_SIGBUS; |
2942 | |
2943 | ret = vmf->vma->vm_ops->page_mkwrite(vmf); |
2944 | /* Restore original flags so that caller is not surprised */ |
2945 | vmf->flags = old_flags; |
2946 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) |
2947 | return ret; |
2948 | if (unlikely(!(ret & VM_FAULT_LOCKED))) { |
2949 | folio_lock(folio); |
2950 | if (!folio->mapping) { |
2951 | folio_unlock(folio); |
2952 | return 0; /* retry */ |
2953 | } |
2954 | ret |= VM_FAULT_LOCKED; |
2955 | } else |
2956 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); |
2957 | return ret; |
2958 | } |
2959 | |
2960 | /* |
2961 | * Handle dirtying of a page in shared file mapping on a write fault. |
2962 | * |
2963 | * The function expects the page to be locked and unlocks it. |
2964 | */ |
2965 | static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf) |
2966 | { |
2967 | struct vm_area_struct *vma = vmf->vma; |
2968 | struct address_space *mapping; |
2969 | struct folio *folio = page_folio(vmf->page); |
2970 | bool dirtied; |
2971 | bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; |
2972 | |
2973 | dirtied = folio_mark_dirty(folio); |
2974 | VM_BUG_ON_FOLIO(folio_test_anon(folio), folio); |
2975 | /* |
2976 | * Take a local copy of the address_space - folio.mapping may be zeroed |
2977 | * by truncate after folio_unlock(). The address_space itself remains |
2978 | * pinned by vma->vm_file's reference. We rely on folio_unlock()'s |
2979 | * release semantics to prevent the compiler from undoing this copying. |
2980 | */ |
2981 | mapping = folio_raw_mapping(folio); |
2982 | folio_unlock(folio); |
2983 | |
2984 | if (!page_mkwrite) |
2985 | file_update_time(file: vma->vm_file); |
2986 | |
2987 | /* |
2988 | * Throttle page dirtying rate down to writeback speed. |
2989 | * |
2990 | * mapping may be NULL here because some device drivers do not |
2991 | * set page.mapping but still dirty their pages |
2992 | * |
2993 | * Drop the mmap_lock before waiting on IO, if we can. The file |
2994 | * is pinning the mapping, as per above. |
2995 | */ |
2996 | if ((dirtied || page_mkwrite) && mapping) { |
2997 | struct file *fpin; |
2998 | |
2999 | fpin = maybe_unlock_mmap_for_io(vmf, NULL); |
3000 | balance_dirty_pages_ratelimited(mapping); |
3001 | if (fpin) { |
3002 | fput(fpin); |
3003 | return VM_FAULT_COMPLETED; |
3004 | } |
3005 | } |
3006 | |
3007 | return 0; |
3008 | } |
3009 | |
3010 | /* |
3011 | * Handle write page faults for pages that can be reused in the current vma |
3012 | * |
3013 | * This can happen either due to the mapping being with the VM_SHARED flag, |
3014 | * or due to us being the last reference standing to the page. In either |
3015 | * case, all we need to do here is to mark the page as writable and update |
3016 | * any related book-keeping. |
3017 | */ |
3018 | static inline void wp_page_reuse(struct vm_fault *vmf, struct folio *folio) |
3019 | __releases(vmf->ptl) |
3020 | { |
3021 | struct vm_area_struct *vma = vmf->vma; |
3022 | pte_t entry; |
3023 | |
3024 | VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE)); |
3025 | |
3026 | if (folio) { |
3027 | VM_BUG_ON(folio_test_anon(folio) && |
3028 | !PageAnonExclusive(vmf->page)); |
3029 | /* |
3030 | * Clear the folio's cpupid information as the existing |
3031 | * information potentially belongs to a now completely |
3032 | * unrelated process. |
3033 | */ |
3034 | folio_xchg_last_cpupid(folio, (1 << LAST_CPUPID_SHIFT) - 1); |
3035 | } |
3036 | |
3037 | flush_cache_page(vma, vmaddr: vmf->address, pfn: pte_pfn(pte: vmf->orig_pte)); |
3038 | entry = pte_mkyoung(pte: vmf->orig_pte); |
3039 | entry = maybe_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
3040 | if (ptep_set_access_flags(vma, address: vmf->address, ptep: vmf->pte, entry, dirty: 1)) |
3041 | update_mmu_cache_range(vmf, vma, addr: vmf->address, ptep: vmf->pte, nr: 1); |
3042 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3043 | count_vm_event(item: PGREUSE); |
3044 | } |
3045 | |
3046 | /* |
3047 | * We could add a bitflag somewhere, but for now, we know that all |
3048 | * vm_ops that have a ->map_pages have been audited and don't need |
3049 | * the mmap_lock to be held. |
3050 | */ |
3051 | static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf) |
3052 | { |
3053 | struct vm_area_struct *vma = vmf->vma; |
3054 | |
3055 | if (vma->vm_ops->map_pages || !(vmf->flags & FAULT_FLAG_VMA_LOCK)) |
3056 | return 0; |
3057 | vma_end_read(vma); |
3058 | return VM_FAULT_RETRY; |
3059 | } |
3060 | |
3061 | static vm_fault_t vmf_anon_prepare(struct vm_fault *vmf) |
3062 | { |
3063 | struct vm_area_struct *vma = vmf->vma; |
3064 | |
3065 | if (likely(vma->anon_vma)) |
3066 | return 0; |
3067 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { |
3068 | vma_end_read(vma); |
3069 | return VM_FAULT_RETRY; |
3070 | } |
3071 | if (__anon_vma_prepare(vma)) |
3072 | return VM_FAULT_OOM; |
3073 | return 0; |
3074 | } |
3075 | |
3076 | /* |
3077 | * Handle the case of a page which we actually need to copy to a new page, |
3078 | * either due to COW or unsharing. |
3079 | * |
3080 | * Called with mmap_lock locked and the old page referenced, but |
3081 | * without the ptl held. |
3082 | * |
3083 | * High level logic flow: |
3084 | * |
3085 | * - Allocate a page, copy the content of the old page to the new one. |
3086 | * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. |
3087 | * - Take the PTL. If the pte changed, bail out and release the allocated page |
3088 | * - If the pte is still the way we remember it, update the page table and all |
3089 | * relevant references. This includes dropping the reference the page-table |
3090 | * held to the old page, as well as updating the rmap. |
3091 | * - In any case, unlock the PTL and drop the reference we took to the old page. |
3092 | */ |
3093 | static vm_fault_t wp_page_copy(struct vm_fault *vmf) |
3094 | { |
3095 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
3096 | struct vm_area_struct *vma = vmf->vma; |
3097 | struct mm_struct *mm = vma->vm_mm; |
3098 | struct folio *old_folio = NULL; |
3099 | struct folio *new_folio = NULL; |
3100 | pte_t entry; |
3101 | int page_copied = 0; |
3102 | struct mmu_notifier_range range; |
3103 | vm_fault_t ret; |
3104 | |
3105 | delayacct_wpcopy_start(); |
3106 | |
3107 | if (vmf->page) |
3108 | old_folio = page_folio(vmf->page); |
3109 | ret = vmf_anon_prepare(vmf); |
3110 | if (unlikely(ret)) |
3111 | goto out; |
3112 | |
3113 | if (is_zero_pfn(pfn: pte_pfn(pte: vmf->orig_pte))) { |
3114 | new_folio = vma_alloc_zeroed_movable_folio(vma, vmf->address); |
3115 | if (!new_folio) |
3116 | goto oom; |
3117 | } else { |
3118 | int err; |
3119 | new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, order: 0, vma, |
3120 | addr: vmf->address, hugepage: false); |
3121 | if (!new_folio) |
3122 | goto oom; |
3123 | |
3124 | err = __wp_page_copy_user(dst: &new_folio->page, src: vmf->page, vmf); |
3125 | if (err) { |
3126 | /* |
3127 | * COW failed, if the fault was solved by other, |
3128 | * it's fine. If not, userspace would re-fault on |
3129 | * the same address and we will handle the fault |
3130 | * from the second attempt. |
3131 | * The -EHWPOISON case will not be retried. |
3132 | */ |
3133 | folio_put(folio: new_folio); |
3134 | if (old_folio) |
3135 | folio_put(folio: old_folio); |
3136 | |
3137 | delayacct_wpcopy_end(); |
3138 | return err == -EHWPOISON ? VM_FAULT_HWPOISON : 0; |
3139 | } |
3140 | kmsan_copy_page_meta(dst: &new_folio->page, src: vmf->page); |
3141 | } |
3142 | |
3143 | if (mem_cgroup_charge(folio: new_folio, mm, GFP_KERNEL)) |
3144 | goto oom_free_new; |
3145 | folio_throttle_swaprate(folio: new_folio, GFP_KERNEL); |
3146 | |
3147 | __folio_mark_uptodate(folio: new_folio); |
3148 | |
3149 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_CLEAR, flags: 0, mm, |
3150 | start: vmf->address & PAGE_MASK, |
3151 | end: (vmf->address & PAGE_MASK) + PAGE_SIZE); |
3152 | mmu_notifier_invalidate_range_start(range: &range); |
3153 | |
3154 | /* |
3155 | * Re-check the pte - we dropped the lock |
3156 | */ |
3157 | vmf->pte = pte_offset_map_lock(mm, pmd: vmf->pmd, addr: vmf->address, ptlp: &vmf->ptl); |
3158 | if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
3159 | if (old_folio) { |
3160 | if (!folio_test_anon(folio: old_folio)) { |
3161 | dec_mm_counter(mm, member: mm_counter_file(page: &old_folio->page)); |
3162 | inc_mm_counter(mm, member: MM_ANONPAGES); |
3163 | } |
3164 | } else { |
3165 | ksm_might_unmap_zero_page(mm, pte: vmf->orig_pte); |
3166 | inc_mm_counter(mm, member: MM_ANONPAGES); |
3167 | } |
3168 | flush_cache_page(vma, vmaddr: vmf->address, pfn: pte_pfn(pte: vmf->orig_pte)); |
3169 | entry = mk_pte(&new_folio->page, vma->vm_page_prot); |
3170 | entry = pte_sw_mkyoung(pte: entry); |
3171 | if (unlikely(unshare)) { |
3172 | if (pte_soft_dirty(pte: vmf->orig_pte)) |
3173 | entry = pte_mksoft_dirty(pte: entry); |
3174 | if (pte_uffd_wp(pte: vmf->orig_pte)) |
3175 | entry = pte_mkuffd_wp(pte: entry); |
3176 | } else { |
3177 | entry = maybe_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
3178 | } |
3179 | |
3180 | /* |
3181 | * Clear the pte entry and flush it first, before updating the |
3182 | * pte with the new entry, to keep TLBs on different CPUs in |
3183 | * sync. This code used to set the new PTE then flush TLBs, but |
3184 | * that left a window where the new PTE could be loaded into |
3185 | * some TLBs while the old PTE remains in others. |
3186 | */ |
3187 | ptep_clear_flush(vma, address: vmf->address, ptep: vmf->pte); |
3188 | folio_add_new_anon_rmap(new_folio, vma, address: vmf->address); |
3189 | folio_add_lru_vma(new_folio, vma); |
3190 | /* |
3191 | * We call the notify macro here because, when using secondary |
3192 | * mmu page tables (such as kvm shadow page tables), we want the |
3193 | * new page to be mapped directly into the secondary page table. |
3194 | */ |
3195 | BUG_ON(unshare && pte_write(entry)); |
3196 | set_pte_at_notify(mm, vmf->address, vmf->pte, entry); |
3197 | update_mmu_cache_range(vmf, vma, addr: vmf->address, ptep: vmf->pte, nr: 1); |
3198 | if (old_folio) { |
3199 | /* |
3200 | * Only after switching the pte to the new page may |
3201 | * we remove the mapcount here. Otherwise another |
3202 | * process may come and find the rmap count decremented |
3203 | * before the pte is switched to the new page, and |
3204 | * "reuse" the old page writing into it while our pte |
3205 | * here still points into it and can be read by other |
3206 | * threads. |
3207 | * |
3208 | * The critical issue is to order this |
3209 | * page_remove_rmap with the ptp_clear_flush above. |
3210 | * Those stores are ordered by (if nothing else,) |
3211 | * the barrier present in the atomic_add_negative |
3212 | * in page_remove_rmap. |
3213 | * |
3214 | * Then the TLB flush in ptep_clear_flush ensures that |
3215 | * no process can access the old page before the |
3216 | * decremented mapcount is visible. And the old page |
3217 | * cannot be reused until after the decremented |
3218 | * mapcount is visible. So transitively, TLBs to |
3219 | * old page will be flushed before it can be reused. |
3220 | */ |
3221 | page_remove_rmap(vmf->page, vma, compound: false); |
3222 | } |
3223 | |
3224 | /* Free the old page.. */ |
3225 | new_folio = old_folio; |
3226 | page_copied = 1; |
3227 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3228 | } else if (vmf->pte) { |
3229 | update_mmu_tlb(vma, address: vmf->address, ptep: vmf->pte); |
3230 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3231 | } |
3232 | |
3233 | mmu_notifier_invalidate_range_end(range: &range); |
3234 | |
3235 | if (new_folio) |
3236 | folio_put(folio: new_folio); |
3237 | if (old_folio) { |
3238 | if (page_copied) |
3239 | free_swap_cache(page: &old_folio->page); |
3240 | folio_put(folio: old_folio); |
3241 | } |
3242 | |
3243 | delayacct_wpcopy_end(); |
3244 | return 0; |
3245 | oom_free_new: |
3246 | folio_put(folio: new_folio); |
3247 | oom: |
3248 | ret = VM_FAULT_OOM; |
3249 | out: |
3250 | if (old_folio) |
3251 | folio_put(folio: old_folio); |
3252 | |
3253 | delayacct_wpcopy_end(); |
3254 | return ret; |
3255 | } |
3256 | |
3257 | /** |
3258 | * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE |
3259 | * writeable once the page is prepared |
3260 | * |
3261 | * @vmf: structure describing the fault |
3262 | * @folio: the folio of vmf->page |
3263 | * |
3264 | * This function handles all that is needed to finish a write page fault in a |
3265 | * shared mapping due to PTE being read-only once the mapped page is prepared. |
3266 | * It handles locking of PTE and modifying it. |
3267 | * |
3268 | * The function expects the page to be locked or other protection against |
3269 | * concurrent faults / writeback (such as DAX radix tree locks). |
3270 | * |
3271 | * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before |
3272 | * we acquired PTE lock. |
3273 | */ |
3274 | static vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf, struct folio *folio) |
3275 | { |
3276 | WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); |
3277 | vmf->pte = pte_offset_map_lock(mm: vmf->vma->vm_mm, pmd: vmf->pmd, addr: vmf->address, |
3278 | ptlp: &vmf->ptl); |
3279 | if (!vmf->pte) |
3280 | return VM_FAULT_NOPAGE; |
3281 | /* |
3282 | * We might have raced with another page fault while we released the |
3283 | * pte_offset_map_lock. |
3284 | */ |
3285 | if (!pte_same(a: ptep_get(ptep: vmf->pte), b: vmf->orig_pte)) { |
3286 | update_mmu_tlb(vma: vmf->vma, address: vmf->address, ptep: vmf->pte); |
3287 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3288 | return VM_FAULT_NOPAGE; |
3289 | } |
3290 | wp_page_reuse(vmf, folio); |
3291 | return 0; |
3292 | } |
3293 | |
3294 | /* |
3295 | * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED |
3296 | * mapping |
3297 | */ |
3298 | static vm_fault_t wp_pfn_shared(struct vm_fault *vmf) |
3299 | { |
3300 | struct vm_area_struct *vma = vmf->vma; |
3301 | |
3302 | if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { |
3303 | vm_fault_t ret; |
3304 | |
3305 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3306 | ret = vmf_can_call_fault(vmf); |
3307 | if (ret) |
3308 | return ret; |
3309 | |
3310 | vmf->flags |= FAULT_FLAG_MKWRITE; |
3311 | ret = vma->vm_ops->pfn_mkwrite(vmf); |
3312 | if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) |
3313 | return ret; |
3314 | return finish_mkwrite_fault(vmf, NULL); |
3315 | } |
3316 | wp_page_reuse(vmf, NULL); |
3317 | return 0; |
3318 | } |
3319 | |
3320 | static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio) |
3321 | __releases(vmf->ptl) |
3322 | { |
3323 | struct vm_area_struct *vma = vmf->vma; |
3324 | vm_fault_t ret = 0; |
3325 | |
3326 | folio_get(folio); |
3327 | |
3328 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) { |
3329 | vm_fault_t tmp; |
3330 | |
3331 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3332 | tmp = vmf_can_call_fault(vmf); |
3333 | if (tmp) { |
3334 | folio_put(folio); |
3335 | return tmp; |
3336 | } |
3337 | |
3338 | tmp = do_page_mkwrite(vmf, folio); |
3339 | if (unlikely(!tmp || (tmp & |
3340 | (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
3341 | folio_put(folio); |
3342 | return tmp; |
3343 | } |
3344 | tmp = finish_mkwrite_fault(vmf, folio); |
3345 | if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
3346 | folio_unlock(folio); |
3347 | folio_put(folio); |
3348 | return tmp; |
3349 | } |
3350 | } else { |
3351 | wp_page_reuse(vmf, folio); |
3352 | folio_lock(folio); |
3353 | } |
3354 | ret |= fault_dirty_shared_page(vmf); |
3355 | folio_put(folio); |
3356 | |
3357 | return ret; |
3358 | } |
3359 | |
3360 | static bool wp_can_reuse_anon_folio(struct folio *folio, |
3361 | struct vm_area_struct *vma) |
3362 | { |
3363 | /* |
3364 | * We have to verify under folio lock: these early checks are |
3365 | * just an optimization to avoid locking the folio and freeing |
3366 | * the swapcache if there is little hope that we can reuse. |
3367 | * |
3368 | * KSM doesn't necessarily raise the folio refcount. |
3369 | */ |
3370 | if (folio_test_ksm(folio) || folio_ref_count(folio) > 3) |
3371 | return false; |
3372 | if (!folio_test_lru(folio)) |
3373 | /* |
3374 | * We cannot easily detect+handle references from |
3375 | * remote LRU caches or references to LRU folios. |
3376 | */ |
3377 | lru_add_drain(); |
3378 | if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio)) |
3379 | return false; |
3380 | if (!folio_trylock(folio)) |
3381 | return false; |
3382 | if (folio_test_swapcache(folio)) |
3383 | folio_free_swap(folio); |
3384 | if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) { |
3385 | folio_unlock(folio); |
3386 | return false; |
3387 | } |
3388 | /* |
3389 | * Ok, we've got the only folio reference from our mapping |
3390 | * and the folio is locked, it's dark out, and we're wearing |
3391 | * sunglasses. Hit it. |
3392 | */ |
3393 | folio_move_anon_rmap(folio, vma); |
3394 | folio_unlock(folio); |
3395 | return true; |
3396 | } |
3397 | |
3398 | /* |
3399 | * This routine handles present pages, when |
3400 | * * users try to write to a shared page (FAULT_FLAG_WRITE) |
3401 | * * GUP wants to take a R/O pin on a possibly shared anonymous page |
3402 | * (FAULT_FLAG_UNSHARE) |
3403 | * |
3404 | * It is done by copying the page to a new address and decrementing the |
3405 | * shared-page counter for the old page. |
3406 | * |
3407 | * Note that this routine assumes that the protection checks have been |
3408 | * done by the caller (the low-level page fault routine in most cases). |
3409 | * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've |
3410 | * done any necessary COW. |
3411 | * |
3412 | * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even |
3413 | * though the page will change only once the write actually happens. This |
3414 | * avoids a few races, and potentially makes it more efficient. |
3415 | * |
3416 | * We enter with non-exclusive mmap_lock (to exclude vma changes, |
3417 | * but allow concurrent faults), with pte both mapped and locked. |
3418 | * We return with mmap_lock still held, but pte unmapped and unlocked. |
3419 | */ |
3420 | static vm_fault_t do_wp_page(struct vm_fault *vmf) |
3421 | __releases(vmf->ptl) |
3422 | { |
3423 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
3424 | struct vm_area_struct *vma = vmf->vma; |
3425 | struct folio *folio = NULL; |
3426 | pte_t pte; |
3427 | |
3428 | if (likely(!unshare)) { |
3429 | if (userfaultfd_pte_wp(vma, pte: ptep_get(ptep: vmf->pte))) { |
3430 | if (!userfaultfd_wp_async(vma)) { |
3431 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3432 | return handle_userfault(vmf, VM_UFFD_WP); |
3433 | } |
3434 | |
3435 | /* |
3436 | * Nothing needed (cache flush, TLB invalidations, |
3437 | * etc.) because we're only removing the uffd-wp bit, |
3438 | * which is completely invisible to the user. |
3439 | */ |
3440 | pte = pte_clear_uffd_wp(pte: ptep_get(ptep: vmf->pte)); |
3441 | |
3442 | set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); |
3443 | /* |
3444 | * Update this to be prepared for following up CoW |
3445 | * handling |
3446 | */ |
3447 | vmf->orig_pte = pte; |
3448 | } |
3449 | |
3450 | /* |
3451 | * Userfaultfd write-protect can defer flushes. Ensure the TLB |
3452 | * is flushed in this case before copying. |
3453 | */ |
3454 | if (unlikely(userfaultfd_wp(vmf->vma) && |
3455 | mm_tlb_flush_pending(vmf->vma->vm_mm))) |
3456 | flush_tlb_page(vma: vmf->vma, a: vmf->address); |
3457 | } |
3458 | |
3459 | vmf->page = vm_normal_page(vma, addr: vmf->address, pte: vmf->orig_pte); |
3460 | |
3461 | if (vmf->page) |
3462 | folio = page_folio(vmf->page); |
3463 | |
3464 | /* |
3465 | * Shared mapping: we are guaranteed to have VM_WRITE and |
3466 | * FAULT_FLAG_WRITE set at this point. |
3467 | */ |
3468 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { |
3469 | /* |
3470 | * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a |
3471 | * VM_PFNMAP VMA. |
3472 | * |
3473 | * We should not cow pages in a shared writeable mapping. |
3474 | * Just mark the pages writable and/or call ops->pfn_mkwrite. |
3475 | */ |
3476 | if (!vmf->page) |
3477 | return wp_pfn_shared(vmf); |
3478 | return wp_page_shared(vmf, folio); |
3479 | } |
3480 | |
3481 | /* |
3482 | * Private mapping: create an exclusive anonymous page copy if reuse |
3483 | * is impossible. We might miss VM_WRITE for FOLL_FORCE handling. |
3484 | * |
3485 | * If we encounter a page that is marked exclusive, we must reuse |
3486 | * the page without further checks. |
3487 | */ |
3488 | if (folio && folio_test_anon(folio) && |
3489 | (PageAnonExclusive(page: vmf->page) || wp_can_reuse_anon_folio(folio, vma))) { |
3490 | if (!PageAnonExclusive(page: vmf->page)) |
3491 | SetPageAnonExclusive(vmf->page); |
3492 | if (unlikely(unshare)) { |
3493 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3494 | return 0; |
3495 | } |
3496 | wp_page_reuse(vmf, folio); |
3497 | return 0; |
3498 | } |
3499 | /* |
3500 | * Ok, we need to copy. Oh, well.. |
3501 | */ |
3502 | if (folio) |
3503 | folio_get(folio); |
3504 | |
3505 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3506 | #ifdef CONFIG_KSM |
3507 | if (folio && folio_test_ksm(folio)) |
3508 | count_vm_event(item: COW_KSM); |
3509 | #endif |
3510 | return wp_page_copy(vmf); |
3511 | } |
3512 | |
3513 | static void unmap_mapping_range_vma(struct vm_area_struct *vma, |
3514 | unsigned long start_addr, unsigned long end_addr, |
3515 | struct zap_details *details) |
3516 | { |
3517 | zap_page_range_single(vma, address: start_addr, size: end_addr - start_addr, details); |
3518 | } |
3519 | |
3520 | static inline void unmap_mapping_range_tree(struct rb_root_cached *root, |
3521 | pgoff_t first_index, |
3522 | pgoff_t last_index, |
3523 | struct zap_details *details) |
3524 | { |
3525 | struct vm_area_struct *vma; |
3526 | pgoff_t vba, vea, zba, zea; |
3527 | |
3528 | vma_interval_tree_foreach(vma, root, first_index, last_index) { |
3529 | vba = vma->vm_pgoff; |
3530 | vea = vba + vma_pages(vma) - 1; |
3531 | zba = max(first_index, vba); |
3532 | zea = min(last_index, vea); |
3533 | |
3534 | unmap_mapping_range_vma(vma, |
3535 | start_addr: ((zba - vba) << PAGE_SHIFT) + vma->vm_start, |
3536 | end_addr: ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, |
3537 | details); |
3538 | } |
3539 | } |
3540 | |
3541 | /** |
3542 | * unmap_mapping_folio() - Unmap single folio from processes. |
3543 | * @folio: The locked folio to be unmapped. |
3544 | * |
3545 | * Unmap this folio from any userspace process which still has it mmaped. |
3546 | * Typically, for efficiency, the range of nearby pages has already been |
3547 | * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once |
3548 | * truncation or invalidation holds the lock on a folio, it may find that |
3549 | * the page has been remapped again: and then uses unmap_mapping_folio() |
3550 | * to unmap it finally. |
3551 | */ |
3552 | void unmap_mapping_folio(struct folio *folio) |
3553 | { |
3554 | struct address_space *mapping = folio->mapping; |
3555 | struct zap_details details = { }; |
3556 | pgoff_t first_index; |
3557 | pgoff_t last_index; |
3558 | |
3559 | VM_BUG_ON(!folio_test_locked(folio)); |
3560 | |
3561 | first_index = folio->index; |
3562 | last_index = folio_next_index(folio) - 1; |
3563 | |
3564 | details.even_cows = false; |
3565 | details.single_folio = folio; |
3566 | details.zap_flags = ZAP_FLAG_DROP_MARKER; |
3567 | |
3568 | i_mmap_lock_read(mapping); |
3569 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) |
3570 | unmap_mapping_range_tree(root: &mapping->i_mmap, first_index, |
3571 | last_index, details: &details); |
3572 | i_mmap_unlock_read(mapping); |
3573 | } |
3574 | |
3575 | /** |
3576 | * unmap_mapping_pages() - Unmap pages from processes. |
3577 | * @mapping: The address space containing pages to be unmapped. |
3578 | * @start: Index of first page to be unmapped. |
3579 | * @nr: Number of pages to be unmapped. 0 to unmap to end of file. |
3580 | * @even_cows: Whether to unmap even private COWed pages. |
3581 | * |
3582 | * Unmap the pages in this address space from any userspace process which |
3583 | * has them mmaped. Generally, you want to remove COWed pages as well when |
3584 | * a file is being truncated, but not when invalidating pages from the page |
3585 | * cache. |
3586 | */ |
3587 | void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, |
3588 | pgoff_t nr, bool even_cows) |
3589 | { |
3590 | struct zap_details details = { }; |
3591 | pgoff_t first_index = start; |
3592 | pgoff_t last_index = start + nr - 1; |
3593 | |
3594 | details.even_cows = even_cows; |
3595 | if (last_index < first_index) |
3596 | last_index = ULONG_MAX; |
3597 | |
3598 | i_mmap_lock_read(mapping); |
3599 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) |
3600 | unmap_mapping_range_tree(root: &mapping->i_mmap, first_index, |
3601 | last_index, details: &details); |
3602 | i_mmap_unlock_read(mapping); |
3603 | } |
3604 | EXPORT_SYMBOL_GPL(unmap_mapping_pages); |
3605 | |
3606 | /** |
3607 | * unmap_mapping_range - unmap the portion of all mmaps in the specified |
3608 | * address_space corresponding to the specified byte range in the underlying |
3609 | * file. |
3610 | * |
3611 | * @mapping: the address space containing mmaps to be unmapped. |
3612 | * @holebegin: byte in first page to unmap, relative to the start of |
3613 | * the underlying file. This will be rounded down to a PAGE_SIZE |
3614 | * boundary. Note that this is different from truncate_pagecache(), which |
3615 | * must keep the partial page. In contrast, we must get rid of |
3616 | * partial pages. |
3617 | * @holelen: size of prospective hole in bytes. This will be rounded |
3618 | * up to a PAGE_SIZE boundary. A holelen of zero truncates to the |
3619 | * end of the file. |
3620 | * @even_cows: 1 when truncating a file, unmap even private COWed pages; |
3621 | * but 0 when invalidating pagecache, don't throw away private data. |
3622 | */ |
3623 | void unmap_mapping_range(struct address_space *mapping, |
3624 | loff_t const holebegin, loff_t const holelen, int even_cows) |
3625 | { |
3626 | pgoff_t hba = holebegin >> PAGE_SHIFT; |
3627 | pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
3628 | |
3629 | /* Check for overflow. */ |
3630 | if (sizeof(holelen) > sizeof(hlen)) { |
3631 | long long holeend = |
3632 | (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
3633 | if (holeend & ~(long long)ULONG_MAX) |
3634 | hlen = ULONG_MAX - hba + 1; |
3635 | } |
3636 | |
3637 | unmap_mapping_pages(mapping, hba, hlen, even_cows); |
3638 | } |
3639 | EXPORT_SYMBOL(unmap_mapping_range); |
3640 | |
3641 | /* |
3642 | * Restore a potential device exclusive pte to a working pte entry |
3643 | */ |
3644 | static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) |
3645 | { |
3646 | struct folio *folio = page_folio(vmf->page); |
3647 | struct vm_area_struct *vma = vmf->vma; |
3648 | struct mmu_notifier_range range; |
3649 | vm_fault_t ret; |
3650 | |
3651 | /* |
3652 | * We need a reference to lock the folio because we don't hold |
3653 | * the PTL so a racing thread can remove the device-exclusive |
3654 | * entry and unmap it. If the folio is free the entry must |
3655 | * have been removed already. If it happens to have already |
3656 | * been re-allocated after being freed all we do is lock and |
3657 | * unlock it. |
3658 | */ |
3659 | if (!folio_try_get(folio)) |
3660 | return 0; |
3661 | |
3662 | ret = folio_lock_or_retry(folio, vmf); |
3663 | if (ret) { |
3664 | folio_put(folio); |
3665 | return ret; |
3666 | } |
3667 | mmu_notifier_range_init_owner(range: &range, event: MMU_NOTIFY_EXCLUSIVE, flags: 0, |
3668 | mm: vma->vm_mm, start: vmf->address & PAGE_MASK, |
3669 | end: (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL); |
3670 | mmu_notifier_invalidate_range_start(range: &range); |
3671 | |
3672 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, addr: vmf->address, |
3673 | ptlp: &vmf->ptl); |
3674 | if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) |
3675 | restore_exclusive_pte(vma, page: vmf->page, address: vmf->address, ptep: vmf->pte); |
3676 | |
3677 | if (vmf->pte) |
3678 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3679 | folio_unlock(folio); |
3680 | folio_put(folio); |
3681 | |
3682 | mmu_notifier_invalidate_range_end(range: &range); |
3683 | return 0; |
3684 | } |
3685 | |
3686 | static inline bool should_try_to_free_swap(struct folio *folio, |
3687 | struct vm_area_struct *vma, |
3688 | unsigned int fault_flags) |
3689 | { |
3690 | if (!folio_test_swapcache(folio)) |
3691 | return false; |
3692 | if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) || |
3693 | folio_test_mlocked(folio)) |
3694 | return true; |
3695 | /* |
3696 | * If we want to map a page that's in the swapcache writable, we |
3697 | * have to detect via the refcount if we're really the exclusive |
3698 | * user. Try freeing the swapcache to get rid of the swapcache |
3699 | * reference only in case it's likely that we'll be the exlusive user. |
3700 | */ |
3701 | return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) && |
3702 | folio_ref_count(folio) == 2; |
3703 | } |
3704 | |
3705 | static vm_fault_t pte_marker_clear(struct vm_fault *vmf) |
3706 | { |
3707 | vmf->pte = pte_offset_map_lock(mm: vmf->vma->vm_mm, pmd: vmf->pmd, |
3708 | addr: vmf->address, ptlp: &vmf->ptl); |
3709 | if (!vmf->pte) |
3710 | return 0; |
3711 | /* |
3712 | * Be careful so that we will only recover a special uffd-wp pte into a |
3713 | * none pte. Otherwise it means the pte could have changed, so retry. |
3714 | * |
3715 | * This should also cover the case where e.g. the pte changed |
3716 | * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_POISONED. |
3717 | * So is_pte_marker() check is not enough to safely drop the pte. |
3718 | */ |
3719 | if (pte_same(a: vmf->orig_pte, b: ptep_get(ptep: vmf->pte))) |
3720 | pte_clear(mm: vmf->vma->vm_mm, addr: vmf->address, ptep: vmf->pte); |
3721 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3722 | return 0; |
3723 | } |
3724 | |
3725 | static vm_fault_t do_pte_missing(struct vm_fault *vmf) |
3726 | { |
3727 | if (vma_is_anonymous(vma: vmf->vma)) |
3728 | return do_anonymous_page(vmf); |
3729 | else |
3730 | return do_fault(vmf); |
3731 | } |
3732 | |
3733 | /* |
3734 | * This is actually a page-missing access, but with uffd-wp special pte |
3735 | * installed. It means this pte was wr-protected before being unmapped. |
3736 | */ |
3737 | static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf) |
3738 | { |
3739 | /* |
3740 | * Just in case there're leftover special ptes even after the region |
3741 | * got unregistered - we can simply clear them. |
3742 | */ |
3743 | if (unlikely(!userfaultfd_wp(vmf->vma))) |
3744 | return pte_marker_clear(vmf); |
3745 | |
3746 | return do_pte_missing(vmf); |
3747 | } |
3748 | |
3749 | static vm_fault_t handle_pte_marker(struct vm_fault *vmf) |
3750 | { |
3751 | swp_entry_t entry = pte_to_swp_entry(pte: vmf->orig_pte); |
3752 | unsigned long marker = pte_marker_get(entry); |
3753 | |
3754 | /* |
3755 | * PTE markers should never be empty. If anything weird happened, |
3756 | * the best thing to do is to kill the process along with its mm. |
3757 | */ |
3758 | if (WARN_ON_ONCE(!marker)) |
3759 | return VM_FAULT_SIGBUS; |
3760 | |
3761 | /* Higher priority than uffd-wp when data corrupted */ |
3762 | if (marker & PTE_MARKER_POISONED) |
3763 | return VM_FAULT_HWPOISON; |
3764 | |
3765 | if (pte_marker_entry_uffd_wp(entry)) |
3766 | return pte_marker_handle_uffd_wp(vmf); |
3767 | |
3768 | /* This is an unknown pte marker */ |
3769 | return VM_FAULT_SIGBUS; |
3770 | } |
3771 | |
3772 | /* |
3773 | * We enter with non-exclusive mmap_lock (to exclude vma changes, |
3774 | * but allow concurrent faults), and pte mapped but not yet locked. |
3775 | * We return with pte unmapped and unlocked. |
3776 | * |
3777 | * We return with the mmap_lock locked or unlocked in the same cases |
3778 | * as does filemap_fault(). |
3779 | */ |
3780 | vm_fault_t do_swap_page(struct vm_fault *vmf) |
3781 | { |
3782 | struct vm_area_struct *vma = vmf->vma; |
3783 | struct folio *swapcache, *folio = NULL; |
3784 | struct page *page; |
3785 | struct swap_info_struct *si = NULL; |
3786 | rmap_t rmap_flags = RMAP_NONE; |
3787 | bool exclusive = false; |
3788 | swp_entry_t entry; |
3789 | pte_t pte; |
3790 | vm_fault_t ret = 0; |
3791 | void *shadow = NULL; |
3792 | |
3793 | if (!pte_unmap_same(vmf)) |
3794 | goto out; |
3795 | |
3796 | entry = pte_to_swp_entry(pte: vmf->orig_pte); |
3797 | if (unlikely(non_swap_entry(entry))) { |
3798 | if (is_migration_entry(entry)) { |
3799 | migration_entry_wait(mm: vma->vm_mm, pmd: vmf->pmd, |
3800 | address: vmf->address); |
3801 | } else if (is_device_exclusive_entry(entry)) { |
3802 | vmf->page = pfn_swap_entry_to_page(entry); |
3803 | ret = remove_device_exclusive_entry(vmf); |
3804 | } else if (is_device_private_entry(entry)) { |
3805 | if (vmf->flags & FAULT_FLAG_VMA_LOCK) { |
3806 | /* |
3807 | * migrate_to_ram is not yet ready to operate |
3808 | * under VMA lock. |
3809 | */ |
3810 | vma_end_read(vma); |
3811 | ret = VM_FAULT_RETRY; |
3812 | goto out; |
3813 | } |
3814 | |
3815 | vmf->page = pfn_swap_entry_to_page(entry); |
3816 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, |
3817 | addr: vmf->address, ptlp: &vmf->ptl); |
3818 | if (unlikely(!vmf->pte || |
3819 | !pte_same(ptep_get(vmf->pte), |
3820 | vmf->orig_pte))) |
3821 | goto unlock; |
3822 | |
3823 | /* |
3824 | * Get a page reference while we know the page can't be |
3825 | * freed. |
3826 | */ |
3827 | get_page(page: vmf->page); |
3828 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
3829 | ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); |
3830 | put_page(page: vmf->page); |
3831 | } else if (is_hwpoison_entry(entry)) { |
3832 | ret = VM_FAULT_HWPOISON; |
3833 | } else if (is_pte_marker_entry(entry)) { |
3834 | ret = handle_pte_marker(vmf); |
3835 | } else { |
3836 | print_bad_pte(vma, addr: vmf->address, pte: vmf->orig_pte, NULL); |
3837 | ret = VM_FAULT_SIGBUS; |
3838 | } |
3839 | goto out; |
3840 | } |
3841 | |
3842 | /* Prevent swapoff from happening to us. */ |
3843 | si = get_swap_device(entry); |
3844 | if (unlikely(!si)) |
3845 | goto out; |
3846 | |
3847 | folio = swap_cache_get_folio(entry, vma, addr: vmf->address); |
3848 | if (folio) |
3849 | page = folio_file_page(folio, index: swp_offset(entry)); |
3850 | swapcache = folio; |
3851 | |
3852 | if (!folio) { |
3853 | if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && |
3854 | __swap_count(entry) == 1) { |
3855 | /* skip swapcache */ |
3856 | folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, order: 0, |
3857 | vma, addr: vmf->address, hugepage: false); |
3858 | page = &folio->page; |
3859 | if (folio) { |
3860 | __folio_set_locked(folio); |
3861 | __folio_set_swapbacked(folio); |
3862 | |
3863 | if (mem_cgroup_swapin_charge_folio(folio, |
3864 | mm: vma->vm_mm, GFP_KERNEL, |
3865 | entry)) { |
3866 | ret = VM_FAULT_OOM; |
3867 | goto out_page; |
3868 | } |
3869 | mem_cgroup_swapin_uncharge_swap(entry); |
3870 | |
3871 | shadow = get_shadow_from_swap_cache(entry); |
3872 | if (shadow) |
3873 | workingset_refault(folio, shadow); |
3874 | |
3875 | folio_add_lru(folio); |
3876 | |
3877 | /* To provide entry to swap_readpage() */ |
3878 | folio->swap = entry; |
3879 | swap_readpage(page, do_poll: true, NULL); |
3880 | folio->private = NULL; |
3881 | } |
3882 | } else { |
3883 | page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
3884 | vmf); |
3885 | if (page) |
3886 | folio = page_folio(page); |
3887 | swapcache = folio; |
3888 | } |
3889 | |
3890 | if (!folio) { |
3891 | /* |
3892 | * Back out if somebody else faulted in this pte |
3893 | * while we released the pte lock. |
3894 | */ |
3895 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, |
3896 | addr: vmf->address, ptlp: &vmf->ptl); |
3897 | if (likely(vmf->pte && |
3898 | pte_same(ptep_get(vmf->pte), vmf->orig_pte))) |
3899 | ret = VM_FAULT_OOM; |
3900 | goto unlock; |
3901 | } |
3902 | |
3903 | /* Had to read the page from swap area: Major fault */ |
3904 | ret = VM_FAULT_MAJOR; |
3905 | count_vm_event(item: PGMAJFAULT); |
3906 | count_memcg_event_mm(mm: vma->vm_mm, idx: PGMAJFAULT); |
3907 | } else if (PageHWPoison(page)) { |
3908 | /* |
3909 | * hwpoisoned dirty swapcache pages are kept for killing |
3910 | * owner processes (which may be unknown at hwpoison time) |
3911 | */ |
3912 | ret = VM_FAULT_HWPOISON; |
3913 | goto out_release; |
3914 | } |
3915 | |
3916 | ret |= folio_lock_or_retry(folio, vmf); |
3917 | if (ret & VM_FAULT_RETRY) |
3918 | goto out_release; |
3919 | |
3920 | if (swapcache) { |
3921 | /* |
3922 | * Make sure folio_free_swap() or swapoff did not release the |
3923 | * swapcache from under us. The page pin, and pte_same test |
3924 | * below, are not enough to exclude that. Even if it is still |
3925 | * swapcache, we need to check that the page's swap has not |
3926 | * changed. |
3927 | */ |
3928 | if (unlikely(!folio_test_swapcache(folio) || |
3929 | page_swap_entry(page).val != entry.val)) |
3930 | goto out_page; |
3931 | |
3932 | /* |
3933 | * KSM sometimes has to copy on read faults, for example, if |
3934 | * page->index of !PageKSM() pages would be nonlinear inside the |
3935 | * anon VMA -- PageKSM() is lost on actual swapout. |
3936 | */ |
3937 | page = ksm_might_need_to_copy(page, vma, address: vmf->address); |
3938 | if (unlikely(!page)) { |
3939 | ret = VM_FAULT_OOM; |
3940 | goto out_page; |
3941 | } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) { |
3942 | ret = VM_FAULT_HWPOISON; |
3943 | goto out_page; |
3944 | } |
3945 | folio = page_folio(page); |
3946 | |
3947 | /* |
3948 | * If we want to map a page that's in the swapcache writable, we |
3949 | * have to detect via the refcount if we're really the exclusive |
3950 | * owner. Try removing the extra reference from the local LRU |
3951 | * caches if required. |
3952 | */ |
3953 | if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache && |
3954 | !folio_test_ksm(folio) && !folio_test_lru(folio)) |
3955 | lru_add_drain(); |
3956 | } |
3957 | |
3958 | folio_throttle_swaprate(folio, GFP_KERNEL); |
3959 | |
3960 | /* |
3961 | * Back out if somebody else already faulted in this pte. |
3962 | */ |
3963 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, addr: vmf->address, |
3964 | ptlp: &vmf->ptl); |
3965 | if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) |
3966 | goto out_nomap; |
3967 | |
3968 | if (unlikely(!folio_test_uptodate(folio))) { |
3969 | ret = VM_FAULT_SIGBUS; |
3970 | goto out_nomap; |
3971 | } |
3972 | |
3973 | /* |
3974 | * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte |
3975 | * must never point at an anonymous page in the swapcache that is |
3976 | * PG_anon_exclusive. Sanity check that this holds and especially, that |
3977 | * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity |
3978 | * check after taking the PT lock and making sure that nobody |
3979 | * concurrently faulted in this page and set PG_anon_exclusive. |
3980 | */ |
3981 | BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio)); |
3982 | BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page)); |
3983 | |
3984 | /* |
3985 | * Check under PT lock (to protect against concurrent fork() sharing |
3986 | * the swap entry concurrently) for certainly exclusive pages. |
3987 | */ |
3988 | if (!folio_test_ksm(folio)) { |
3989 | exclusive = pte_swp_exclusive(pte: vmf->orig_pte); |
3990 | if (folio != swapcache) { |
3991 | /* |
3992 | * We have a fresh page that is not exposed to the |
3993 | * swapcache -> certainly exclusive. |
3994 | */ |
3995 | exclusive = true; |
3996 | } else if (exclusive && folio_test_writeback(folio) && |
3997 | data_race(si->flags & SWP_STABLE_WRITES)) { |
3998 | /* |
3999 | * This is tricky: not all swap backends support |
4000 | * concurrent page modifications while under writeback. |
4001 | * |
4002 | * So if we stumble over such a page in the swapcache |
4003 | * we must not set the page exclusive, otherwise we can |
4004 | * map it writable without further checks and modify it |
4005 | * while still under writeback. |
4006 | * |
4007 | * For these problematic swap backends, simply drop the |
4008 | * exclusive marker: this is perfectly fine as we start |
4009 | * writeback only if we fully unmapped the page and |
4010 | * there are no unexpected references on the page after |
4011 | * unmapping succeeded. After fully unmapped, no |
4012 | * further GUP references (FOLL_GET and FOLL_PIN) can |
4013 | * appear, so dropping the exclusive marker and mapping |
4014 | * it only R/O is fine. |
4015 | */ |
4016 | exclusive = false; |
4017 | } |
4018 | } |
4019 | |
4020 | /* |
4021 | * Some architectures may have to restore extra metadata to the page |
4022 | * when reading from swap. This metadata may be indexed by swap entry |
4023 | * so this must be called before swap_free(). |
4024 | */ |
4025 | arch_swap_restore(entry, folio); |
4026 | |
4027 | /* |
4028 | * Remove the swap entry and conditionally try to free up the swapcache. |
4029 | * We're already holding a reference on the page but haven't mapped it |
4030 | * yet. |
4031 | */ |
4032 | swap_free(entry); |
4033 | if (should_try_to_free_swap(folio, vma, fault_flags: vmf->flags)) |
4034 | folio_free_swap(folio); |
4035 | |
4036 | inc_mm_counter(mm: vma->vm_mm, member: MM_ANONPAGES); |
4037 | dec_mm_counter(mm: vma->vm_mm, member: MM_SWAPENTS); |
4038 | pte = mk_pte(page, vma->vm_page_prot); |
4039 | |
4040 | /* |
4041 | * Same logic as in do_wp_page(); however, optimize for pages that are |
4042 | * certainly not shared either because we just allocated them without |
4043 | * exposing them to the swapcache or because the swap entry indicates |
4044 | * exclusivity. |
4045 | */ |
4046 | if (!folio_test_ksm(folio) && |
4047 | (exclusive || folio_ref_count(folio) == 1)) { |
4048 | if (vmf->flags & FAULT_FLAG_WRITE) { |
4049 | pte = maybe_mkwrite(pte: pte_mkdirty(pte), vma); |
4050 | vmf->flags &= ~FAULT_FLAG_WRITE; |
4051 | } |
4052 | rmap_flags |= RMAP_EXCLUSIVE; |
4053 | } |
4054 | flush_icache_page(vma, page); |
4055 | if (pte_swp_soft_dirty(pte: vmf->orig_pte)) |
4056 | pte = pte_mksoft_dirty(pte); |
4057 | if (pte_swp_uffd_wp(pte: vmf->orig_pte)) |
4058 | pte = pte_mkuffd_wp(pte); |
4059 | vmf->orig_pte = pte; |
4060 | |
4061 | /* ksm created a completely new copy */ |
4062 | if (unlikely(folio != swapcache && swapcache)) { |
4063 | page_add_new_anon_rmap(page, vma, address: vmf->address); |
4064 | folio_add_lru_vma(folio, vma); |
4065 | } else { |
4066 | page_add_anon_rmap(page, vma, address: vmf->address, flags: rmap_flags); |
4067 | } |
4068 | |
4069 | VM_BUG_ON(!folio_test_anon(folio) || |
4070 | (pte_write(pte) && !PageAnonExclusive(page))); |
4071 | set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); |
4072 | arch_do_swap_page(mm: vma->vm_mm, vma, addr: vmf->address, pte, oldpte: vmf->orig_pte); |
4073 | |
4074 | folio_unlock(folio); |
4075 | if (folio != swapcache && swapcache) { |
4076 | /* |
4077 | * Hold the lock to avoid the swap entry to be reused |
4078 | * until we take the PT lock for the pte_same() check |
4079 | * (to avoid false positives from pte_same). For |
4080 | * further safety release the lock after the swap_free |
4081 | * so that the swap count won't change under a |
4082 | * parallel locked swapcache. |
4083 | */ |
4084 | folio_unlock(folio: swapcache); |
4085 | folio_put(folio: swapcache); |
4086 | } |
4087 | |
4088 | if (vmf->flags & FAULT_FLAG_WRITE) { |
4089 | ret |= do_wp_page(vmf); |
4090 | if (ret & VM_FAULT_ERROR) |
4091 | ret &= VM_FAULT_ERROR; |
4092 | goto out; |
4093 | } |
4094 | |
4095 | /* No need to invalidate - it was non-present before */ |
4096 | update_mmu_cache_range(vmf, vma, addr: vmf->address, ptep: vmf->pte, nr: 1); |
4097 | unlock: |
4098 | if (vmf->pte) |
4099 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4100 | out: |
4101 | if (si) |
4102 | put_swap_device(si); |
4103 | return ret; |
4104 | out_nomap: |
4105 | if (vmf->pte) |
4106 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4107 | out_page: |
4108 | folio_unlock(folio); |
4109 | out_release: |
4110 | folio_put(folio); |
4111 | if (folio != swapcache && swapcache) { |
4112 | folio_unlock(folio: swapcache); |
4113 | folio_put(folio: swapcache); |
4114 | } |
4115 | if (si) |
4116 | put_swap_device(si); |
4117 | return ret; |
4118 | } |
4119 | |
4120 | /* |
4121 | * We enter with non-exclusive mmap_lock (to exclude vma changes, |
4122 | * but allow concurrent faults), and pte mapped but not yet locked. |
4123 | * We return with mmap_lock still held, but pte unmapped and unlocked. |
4124 | */ |
4125 | static vm_fault_t do_anonymous_page(struct vm_fault *vmf) |
4126 | { |
4127 | bool uffd_wp = vmf_orig_pte_uffd_wp(vmf); |
4128 | struct vm_area_struct *vma = vmf->vma; |
4129 | struct folio *folio; |
4130 | vm_fault_t ret = 0; |
4131 | pte_t entry; |
4132 | |
4133 | /* File mapping without ->vm_ops ? */ |
4134 | if (vma->vm_flags & VM_SHARED) |
4135 | return VM_FAULT_SIGBUS; |
4136 | |
4137 | /* |
4138 | * Use pte_alloc() instead of pte_alloc_map(), so that OOM can |
4139 | * be distinguished from a transient failure of pte_offset_map(). |
4140 | */ |
4141 | if (pte_alloc(vma->vm_mm, vmf->pmd)) |
4142 | return VM_FAULT_OOM; |
4143 | |
4144 | /* Use the zero-page for reads */ |
4145 | if (!(vmf->flags & FAULT_FLAG_WRITE) && |
4146 | !mm_forbids_zeropage(vma->vm_mm)) { |
4147 | entry = pte_mkspecial(pte: pfn_pte(page_nr: my_zero_pfn(addr: vmf->address), |
4148 | pgprot: vma->vm_page_prot)); |
4149 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, |
4150 | addr: vmf->address, ptlp: &vmf->ptl); |
4151 | if (!vmf->pte) |
4152 | goto unlock; |
4153 | if (vmf_pte_changed(vmf)) { |
4154 | update_mmu_tlb(vma, address: vmf->address, ptep: vmf->pte); |
4155 | goto unlock; |
4156 | } |
4157 | ret = check_stable_address_space(mm: vma->vm_mm); |
4158 | if (ret) |
4159 | goto unlock; |
4160 | /* Deliver the page fault to userland, check inside PT lock */ |
4161 | if (userfaultfd_missing(vma)) { |
4162 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4163 | return handle_userfault(vmf, VM_UFFD_MISSING); |
4164 | } |
4165 | goto setpte; |
4166 | } |
4167 | |
4168 | /* Allocate our own private page. */ |
4169 | if (unlikely(anon_vma_prepare(vma))) |
4170 | goto oom; |
4171 | folio = vma_alloc_zeroed_movable_folio(vma, vmf->address); |
4172 | if (!folio) |
4173 | goto oom; |
4174 | |
4175 | if (mem_cgroup_charge(folio, mm: vma->vm_mm, GFP_KERNEL)) |
4176 | goto oom_free_page; |
4177 | folio_throttle_swaprate(folio, GFP_KERNEL); |
4178 | |
4179 | /* |
4180 | * The memory barrier inside __folio_mark_uptodate makes sure that |
4181 | * preceding stores to the page contents become visible before |
4182 | * the set_pte_at() write. |
4183 | */ |
4184 | __folio_mark_uptodate(folio); |
4185 | |
4186 | entry = mk_pte(&folio->page, vma->vm_page_prot); |
4187 | entry = pte_sw_mkyoung(pte: entry); |
4188 | if (vma->vm_flags & VM_WRITE) |
4189 | entry = pte_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
4190 | |
4191 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, addr: vmf->address, |
4192 | ptlp: &vmf->ptl); |
4193 | if (!vmf->pte) |
4194 | goto release; |
4195 | if (vmf_pte_changed(vmf)) { |
4196 | update_mmu_tlb(vma, address: vmf->address, ptep: vmf->pte); |
4197 | goto release; |
4198 | } |
4199 | |
4200 | ret = check_stable_address_space(mm: vma->vm_mm); |
4201 | if (ret) |
4202 | goto release; |
4203 | |
4204 | /* Deliver the page fault to userland, check inside PT lock */ |
4205 | if (userfaultfd_missing(vma)) { |
4206 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4207 | folio_put(folio); |
4208 | return handle_userfault(vmf, VM_UFFD_MISSING); |
4209 | } |
4210 | |
4211 | inc_mm_counter(mm: vma->vm_mm, member: MM_ANONPAGES); |
4212 | folio_add_new_anon_rmap(folio, vma, address: vmf->address); |
4213 | folio_add_lru_vma(folio, vma); |
4214 | setpte: |
4215 | if (uffd_wp) |
4216 | entry = pte_mkuffd_wp(pte: entry); |
4217 | set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); |
4218 | |
4219 | /* No need to invalidate - it was non-present before */ |
4220 | update_mmu_cache_range(vmf, vma, addr: vmf->address, ptep: vmf->pte, nr: 1); |
4221 | unlock: |
4222 | if (vmf->pte) |
4223 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4224 | return ret; |
4225 | release: |
4226 | folio_put(folio); |
4227 | goto unlock; |
4228 | oom_free_page: |
4229 | folio_put(folio); |
4230 | oom: |
4231 | return VM_FAULT_OOM; |
4232 | } |
4233 | |
4234 | /* |
4235 | * The mmap_lock must have been held on entry, and may have been |
4236 | * released depending on flags and vma->vm_ops->fault() return value. |
4237 | * See filemap_fault() and __lock_page_retry(). |
4238 | */ |
4239 | static vm_fault_t __do_fault(struct vm_fault *vmf) |
4240 | { |
4241 | struct vm_area_struct *vma = vmf->vma; |
4242 | vm_fault_t ret; |
4243 | |
4244 | /* |
4245 | * Preallocate pte before we take page_lock because this might lead to |
4246 | * deadlocks for memcg reclaim which waits for pages under writeback: |
4247 | * lock_page(A) |
4248 | * SetPageWriteback(A) |
4249 | * unlock_page(A) |
4250 | * lock_page(B) |
4251 | * lock_page(B) |
4252 | * pte_alloc_one |
4253 | * shrink_page_list |
4254 | * wait_on_page_writeback(A) |
4255 | * SetPageWriteback(B) |
4256 | * unlock_page(B) |
4257 | * # flush A, B to clear the writeback |
4258 | */ |
4259 | if (pmd_none(pmd: *vmf->pmd) && !vmf->prealloc_pte) { |
4260 | vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); |
4261 | if (!vmf->prealloc_pte) |
4262 | return VM_FAULT_OOM; |
4263 | } |
4264 | |
4265 | ret = vma->vm_ops->fault(vmf); |
4266 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | |
4267 | VM_FAULT_DONE_COW))) |
4268 | return ret; |
4269 | |
4270 | if (unlikely(PageHWPoison(vmf->page))) { |
4271 | struct page *page = vmf->page; |
4272 | vm_fault_t poisonret = VM_FAULT_HWPOISON; |
4273 | if (ret & VM_FAULT_LOCKED) { |
4274 | if (page_mapped(page)) |
4275 | unmap_mapping_pages(page_mapping(page), |
4276 | page->index, 1, false); |
4277 | /* Retry if a clean page was removed from the cache. */ |
4278 | if (invalidate_inode_page(page)) |
4279 | poisonret = VM_FAULT_NOPAGE; |
4280 | unlock_page(page); |
4281 | } |
4282 | put_page(page); |
4283 | vmf->page = NULL; |
4284 | return poisonret; |
4285 | } |
4286 | |
4287 | if (unlikely(!(ret & VM_FAULT_LOCKED))) |
4288 | lock_page(page: vmf->page); |
4289 | else |
4290 | VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); |
4291 | |
4292 | return ret; |
4293 | } |
4294 | |
4295 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
4296 | static void deposit_prealloc_pte(struct vm_fault *vmf) |
4297 | { |
4298 | struct vm_area_struct *vma = vmf->vma; |
4299 | |
4300 | pgtable_trans_huge_deposit(mm: vma->vm_mm, pmdp: vmf->pmd, pgtable: vmf->prealloc_pte); |
4301 | /* |
4302 | * We are going to consume the prealloc table, |
4303 | * count that as nr_ptes. |
4304 | */ |
4305 | mm_inc_nr_ptes(mm: vma->vm_mm); |
4306 | vmf->prealloc_pte = NULL; |
4307 | } |
4308 | |
4309 | vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) |
4310 | { |
4311 | struct vm_area_struct *vma = vmf->vma; |
4312 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
4313 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
4314 | pmd_t entry; |
4315 | vm_fault_t ret = VM_FAULT_FALLBACK; |
4316 | |
4317 | if (!transhuge_vma_suitable(vma, addr: haddr)) |
4318 | return ret; |
4319 | |
4320 | page = compound_head(page); |
4321 | if (compound_order(page) != HPAGE_PMD_ORDER) |
4322 | return ret; |
4323 | |
4324 | /* |
4325 | * Just backoff if any subpage of a THP is corrupted otherwise |
4326 | * the corrupted page may mapped by PMD silently to escape the |
4327 | * check. This kind of THP just can be PTE mapped. Access to |
4328 | * the corrupted subpage should trigger SIGBUS as expected. |
4329 | */ |
4330 | if (unlikely(PageHasHWPoisoned(page))) |
4331 | return ret; |
4332 | |
4333 | /* |
4334 | * Archs like ppc64 need additional space to store information |
4335 | * related to pte entry. Use the preallocated table for that. |
4336 | */ |
4337 | if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { |
4338 | vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); |
4339 | if (!vmf->prealloc_pte) |
4340 | return VM_FAULT_OOM; |
4341 | } |
4342 | |
4343 | vmf->ptl = pmd_lock(mm: vma->vm_mm, pmd: vmf->pmd); |
4344 | if (unlikely(!pmd_none(*vmf->pmd))) |
4345 | goto out; |
4346 | |
4347 | flush_icache_pages(vma, page, HPAGE_PMD_NR); |
4348 | |
4349 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
4350 | if (write) |
4351 | entry = maybe_pmd_mkwrite(pmd: pmd_mkdirty(pmd: entry), vma); |
4352 | |
4353 | add_mm_counter(mm: vma->vm_mm, member: mm_counter_file(page), HPAGE_PMD_NR); |
4354 | page_add_file_rmap(page, vma, compound: true); |
4355 | |
4356 | /* |
4357 | * deposit and withdraw with pmd lock held |
4358 | */ |
4359 | if (arch_needs_pgtable_deposit()) |
4360 | deposit_prealloc_pte(vmf); |
4361 | |
4362 | set_pmd_at(mm: vma->vm_mm, addr: haddr, pmdp: vmf->pmd, pmd: entry); |
4363 | |
4364 | update_mmu_cache_pmd(vma, addr: haddr, pmd: vmf->pmd); |
4365 | |
4366 | /* fault is handled */ |
4367 | ret = 0; |
4368 | count_vm_event(item: THP_FILE_MAPPED); |
4369 | out: |
4370 | spin_unlock(lock: vmf->ptl); |
4371 | return ret; |
4372 | } |
4373 | #else |
4374 | vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) |
4375 | { |
4376 | return VM_FAULT_FALLBACK; |
4377 | } |
4378 | #endif |
4379 | |
4380 | /** |
4381 | * set_pte_range - Set a range of PTEs to point to pages in a folio. |
4382 | * @vmf: Fault decription. |
4383 | * @folio: The folio that contains @page. |
4384 | * @page: The first page to create a PTE for. |
4385 | * @nr: The number of PTEs to create. |
4386 | * @addr: The first address to create a PTE for. |
4387 | */ |
4388 | void set_pte_range(struct vm_fault *vmf, struct folio *folio, |
4389 | struct page *page, unsigned int nr, unsigned long addr) |
4390 | { |
4391 | struct vm_area_struct *vma = vmf->vma; |
4392 | bool uffd_wp = vmf_orig_pte_uffd_wp(vmf); |
4393 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
4394 | bool prefault = in_range(vmf->address, addr, nr * PAGE_SIZE); |
4395 | pte_t entry; |
4396 | |
4397 | flush_icache_pages(vma, page, nr); |
4398 | entry = mk_pte(page, vma->vm_page_prot); |
4399 | |
4400 | if (prefault && arch_wants_old_prefaulted_pte()) |
4401 | entry = pte_mkold(pte: entry); |
4402 | else |
4403 | entry = pte_sw_mkyoung(pte: entry); |
4404 | |
4405 | if (write) |
4406 | entry = maybe_mkwrite(pte: pte_mkdirty(pte: entry), vma); |
4407 | if (unlikely(uffd_wp)) |
4408 | entry = pte_mkuffd_wp(pte: entry); |
4409 | /* copy-on-write page */ |
4410 | if (write && !(vma->vm_flags & VM_SHARED)) { |
4411 | add_mm_counter(mm: vma->vm_mm, member: MM_ANONPAGES, value: nr); |
4412 | VM_BUG_ON_FOLIO(nr != 1, folio); |
4413 | folio_add_new_anon_rmap(folio, vma, address: addr); |
4414 | folio_add_lru_vma(folio, vma); |
4415 | } else { |
4416 | add_mm_counter(mm: vma->vm_mm, member: mm_counter_file(page), value: nr); |
4417 | folio_add_file_rmap_range(folio, page, nr, vma, compound: false); |
4418 | } |
4419 | set_ptes(mm: vma->vm_mm, addr, ptep: vmf->pte, pte: entry, nr); |
4420 | |
4421 | /* no need to invalidate: a not-present page won't be cached */ |
4422 | update_mmu_cache_range(vmf, vma, addr, ptep: vmf->pte, nr); |
4423 | } |
4424 | |
4425 | static bool vmf_pte_changed(struct vm_fault *vmf) |
4426 | { |
4427 | if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID) |
4428 | return !pte_same(a: ptep_get(ptep: vmf->pte), b: vmf->orig_pte); |
4429 | |
4430 | return !pte_none(pte: ptep_get(ptep: vmf->pte)); |
4431 | } |
4432 | |
4433 | /** |
4434 | * finish_fault - finish page fault once we have prepared the page to fault |
4435 | * |
4436 | * @vmf: structure describing the fault |
4437 | * |
4438 | * This function handles all that is needed to finish a page fault once the |
4439 | * page to fault in is prepared. It handles locking of PTEs, inserts PTE for |
4440 | * given page, adds reverse page mapping, handles memcg charges and LRU |
4441 | * addition. |
4442 | * |
4443 | * The function expects the page to be locked and on success it consumes a |
4444 | * reference of a page being mapped (for the PTE which maps it). |
4445 | * |
4446 | * Return: %0 on success, %VM_FAULT_ code in case of error. |
4447 | */ |
4448 | vm_fault_t finish_fault(struct vm_fault *vmf) |
4449 | { |
4450 | struct vm_area_struct *vma = vmf->vma; |
4451 | struct page *page; |
4452 | vm_fault_t ret; |
4453 | |
4454 | /* Did we COW the page? */ |
4455 | if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) |
4456 | page = vmf->cow_page; |
4457 | else |
4458 | page = vmf->page; |
4459 | |
4460 | /* |
4461 | * check even for read faults because we might have lost our CoWed |
4462 | * page |
4463 | */ |
4464 | if (!(vma->vm_flags & VM_SHARED)) { |
4465 | ret = check_stable_address_space(mm: vma->vm_mm); |
4466 | if (ret) |
4467 | return ret; |
4468 | } |
4469 | |
4470 | if (pmd_none(pmd: *vmf->pmd)) { |
4471 | if (PageTransCompound(page)) { |
4472 | ret = do_set_pmd(vmf, page); |
4473 | if (ret != VM_FAULT_FALLBACK) |
4474 | return ret; |
4475 | } |
4476 | |
4477 | if (vmf->prealloc_pte) |
4478 | pmd_install(mm: vma->vm_mm, pmd: vmf->pmd, pte: &vmf->prealloc_pte); |
4479 | else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) |
4480 | return VM_FAULT_OOM; |
4481 | } |
4482 | |
4483 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, |
4484 | addr: vmf->address, ptlp: &vmf->ptl); |
4485 | if (!vmf->pte) |
4486 | return VM_FAULT_NOPAGE; |
4487 | |
4488 | /* Re-check under ptl */ |
4489 | if (likely(!vmf_pte_changed(vmf))) { |
4490 | struct folio *folio = page_folio(page); |
4491 | |
4492 | set_pte_range(vmf, folio, page, nr: 1, addr: vmf->address); |
4493 | ret = 0; |
4494 | } else { |
4495 | update_mmu_tlb(vma, address: vmf->address, ptep: vmf->pte); |
4496 | ret = VM_FAULT_NOPAGE; |
4497 | } |
4498 | |
4499 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4500 | return ret; |
4501 | } |
4502 | |
4503 | static unsigned long fault_around_pages __read_mostly = |
4504 | 65536 >> PAGE_SHIFT; |
4505 | |
4506 | #ifdef CONFIG_DEBUG_FS |
4507 | static int fault_around_bytes_get(void *data, u64 *val) |
4508 | { |
4509 | *val = fault_around_pages << PAGE_SHIFT; |
4510 | return 0; |
4511 | } |
4512 | |
4513 | /* |
4514 | * fault_around_bytes must be rounded down to the nearest page order as it's |
4515 | * what do_fault_around() expects to see. |
4516 | */ |
4517 | static int fault_around_bytes_set(void *data, u64 val) |
4518 | { |
4519 | if (val / PAGE_SIZE > PTRS_PER_PTE) |
4520 | return -EINVAL; |
4521 | |
4522 | /* |
4523 | * The minimum value is 1 page, however this results in no fault-around |
4524 | * at all. See should_fault_around(). |
4525 | */ |
4526 | fault_around_pages = max(rounddown_pow_of_two(val) >> PAGE_SHIFT, 1UL); |
4527 | |
4528 | return 0; |
4529 | } |
4530 | DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, |
4531 | fault_around_bytes_get, fault_around_bytes_set, "%llu\n" ); |
4532 | |
4533 | static int __init fault_around_debugfs(void) |
4534 | { |
4535 | debugfs_create_file_unsafe(name: "fault_around_bytes" , mode: 0644, NULL, NULL, |
4536 | fops: &fault_around_bytes_fops); |
4537 | return 0; |
4538 | } |
4539 | late_initcall(fault_around_debugfs); |
4540 | #endif |
4541 | |
4542 | /* |
4543 | * do_fault_around() tries to map few pages around the fault address. The hope |
4544 | * is that the pages will be needed soon and this will lower the number of |
4545 | * faults to handle. |
4546 | * |
4547 | * It uses vm_ops->map_pages() to map the pages, which skips the page if it's |
4548 | * not ready to be mapped: not up-to-date, locked, etc. |
4549 | * |
4550 | * This function doesn't cross VMA or page table boundaries, in order to call |
4551 | * map_pages() and acquire a PTE lock only once. |
4552 | * |
4553 | * fault_around_pages defines how many pages we'll try to map. |
4554 | * do_fault_around() expects it to be set to a power of two less than or equal |
4555 | * to PTRS_PER_PTE. |
4556 | * |
4557 | * The virtual address of the area that we map is naturally aligned to |
4558 | * fault_around_pages * PAGE_SIZE rounded down to the machine page size |
4559 | * (and therefore to page order). This way it's easier to guarantee |
4560 | * that we don't cross page table boundaries. |
4561 | */ |
4562 | static vm_fault_t do_fault_around(struct vm_fault *vmf) |
4563 | { |
4564 | pgoff_t nr_pages = READ_ONCE(fault_around_pages); |
4565 | pgoff_t pte_off = pte_index(address: vmf->address); |
4566 | /* The page offset of vmf->address within the VMA. */ |
4567 | pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; |
4568 | pgoff_t from_pte, to_pte; |
4569 | vm_fault_t ret; |
4570 | |
4571 | /* The PTE offset of the start address, clamped to the VMA. */ |
4572 | from_pte = max(ALIGN_DOWN(pte_off, nr_pages), |
4573 | pte_off - min(pte_off, vma_off)); |
4574 | |
4575 | /* The PTE offset of the end address, clamped to the VMA and PTE. */ |
4576 | to_pte = min3(from_pte + nr_pages, (pgoff_t)PTRS_PER_PTE, |
4577 | pte_off + vma_pages(vmf->vma) - vma_off) - 1; |
4578 | |
4579 | if (pmd_none(pmd: *vmf->pmd)) { |
4580 | vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); |
4581 | if (!vmf->prealloc_pte) |
4582 | return VM_FAULT_OOM; |
4583 | } |
4584 | |
4585 | rcu_read_lock(); |
4586 | ret = vmf->vma->vm_ops->map_pages(vmf, |
4587 | vmf->pgoff + from_pte - pte_off, |
4588 | vmf->pgoff + to_pte - pte_off); |
4589 | rcu_read_unlock(); |
4590 | |
4591 | return ret; |
4592 | } |
4593 | |
4594 | /* Return true if we should do read fault-around, false otherwise */ |
4595 | static inline bool should_fault_around(struct vm_fault *vmf) |
4596 | { |
4597 | /* No ->map_pages? No way to fault around... */ |
4598 | if (!vmf->vma->vm_ops->map_pages) |
4599 | return false; |
4600 | |
4601 | if (uffd_disable_fault_around(vma: vmf->vma)) |
4602 | return false; |
4603 | |
4604 | /* A single page implies no faulting 'around' at all. */ |
4605 | return fault_around_pages > 1; |
4606 | } |
4607 | |
4608 | static vm_fault_t do_read_fault(struct vm_fault *vmf) |
4609 | { |
4610 | vm_fault_t ret = 0; |
4611 | struct folio *folio; |
4612 | |
4613 | /* |
4614 | * Let's call ->map_pages() first and use ->fault() as fallback |
4615 | * if page by the offset is not ready to be mapped (cold cache or |
4616 | * something). |
4617 | */ |
4618 | if (should_fault_around(vmf)) { |
4619 | ret = do_fault_around(vmf); |
4620 | if (ret) |
4621 | return ret; |
4622 | } |
4623 | |
4624 | ret = vmf_can_call_fault(vmf); |
4625 | if (ret) |
4626 | return ret; |
4627 | |
4628 | ret = __do_fault(vmf); |
4629 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
4630 | return ret; |
4631 | |
4632 | ret |= finish_fault(vmf); |
4633 | folio = page_folio(vmf->page); |
4634 | folio_unlock(folio); |
4635 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
4636 | folio_put(folio); |
4637 | return ret; |
4638 | } |
4639 | |
4640 | static vm_fault_t do_cow_fault(struct vm_fault *vmf) |
4641 | { |
4642 | struct vm_area_struct *vma = vmf->vma; |
4643 | vm_fault_t ret; |
4644 | |
4645 | ret = vmf_can_call_fault(vmf); |
4646 | if (!ret) |
4647 | ret = vmf_anon_prepare(vmf); |
4648 | if (ret) |
4649 | return ret; |
4650 | |
4651 | vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr: vmf->address); |
4652 | if (!vmf->cow_page) |
4653 | return VM_FAULT_OOM; |
4654 | |
4655 | if (mem_cgroup_charge(page_folio(vmf->cow_page), mm: vma->vm_mm, |
4656 | GFP_KERNEL)) { |
4657 | put_page(page: vmf->cow_page); |
4658 | return VM_FAULT_OOM; |
4659 | } |
4660 | folio_throttle_swaprate(page_folio(vmf->cow_page), GFP_KERNEL); |
4661 | |
4662 | ret = __do_fault(vmf); |
4663 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
4664 | goto uncharge_out; |
4665 | if (ret & VM_FAULT_DONE_COW) |
4666 | return ret; |
4667 | |
4668 | copy_user_highpage(to: vmf->cow_page, from: vmf->page, vaddr: vmf->address, vma); |
4669 | __SetPageUptodate(page: vmf->cow_page); |
4670 | |
4671 | ret |= finish_fault(vmf); |
4672 | unlock_page(page: vmf->page); |
4673 | put_page(page: vmf->page); |
4674 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
4675 | goto uncharge_out; |
4676 | return ret; |
4677 | uncharge_out: |
4678 | put_page(page: vmf->cow_page); |
4679 | return ret; |
4680 | } |
4681 | |
4682 | static vm_fault_t do_shared_fault(struct vm_fault *vmf) |
4683 | { |
4684 | struct vm_area_struct *vma = vmf->vma; |
4685 | vm_fault_t ret, tmp; |
4686 | struct folio *folio; |
4687 | |
4688 | ret = vmf_can_call_fault(vmf); |
4689 | if (ret) |
4690 | return ret; |
4691 | |
4692 | ret = __do_fault(vmf); |
4693 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
4694 | return ret; |
4695 | |
4696 | folio = page_folio(vmf->page); |
4697 | |
4698 | /* |
4699 | * Check if the backing address space wants to know that the page is |
4700 | * about to become writable |
4701 | */ |
4702 | if (vma->vm_ops->page_mkwrite) { |
4703 | folio_unlock(folio); |
4704 | tmp = do_page_mkwrite(vmf, folio); |
4705 | if (unlikely(!tmp || |
4706 | (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
4707 | folio_put(folio); |
4708 | return tmp; |
4709 | } |
4710 | } |
4711 | |
4712 | ret |= finish_fault(vmf); |
4713 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | |
4714 | VM_FAULT_RETRY))) { |
4715 | folio_unlock(folio); |
4716 | folio_put(folio); |
4717 | return ret; |
4718 | } |
4719 | |
4720 | ret |= fault_dirty_shared_page(vmf); |
4721 | return ret; |
4722 | } |
4723 | |
4724 | /* |
4725 | * We enter with non-exclusive mmap_lock (to exclude vma changes, |
4726 | * but allow concurrent faults). |
4727 | * The mmap_lock may have been released depending on flags and our |
4728 | * return value. See filemap_fault() and __folio_lock_or_retry(). |
4729 | * If mmap_lock is released, vma may become invalid (for example |
4730 | * by other thread calling munmap()). |
4731 | */ |
4732 | static vm_fault_t do_fault(struct vm_fault *vmf) |
4733 | { |
4734 | struct vm_area_struct *vma = vmf->vma; |
4735 | struct mm_struct *vm_mm = vma->vm_mm; |
4736 | vm_fault_t ret; |
4737 | |
4738 | /* |
4739 | * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND |
4740 | */ |
4741 | if (!vma->vm_ops->fault) { |
4742 | vmf->pte = pte_offset_map_lock(mm: vmf->vma->vm_mm, pmd: vmf->pmd, |
4743 | addr: vmf->address, ptlp: &vmf->ptl); |
4744 | if (unlikely(!vmf->pte)) |
4745 | ret = VM_FAULT_SIGBUS; |
4746 | else { |
4747 | /* |
4748 | * Make sure this is not a temporary clearing of pte |
4749 | * by holding ptl and checking again. A R/M/W update |
4750 | * of pte involves: take ptl, clearing the pte so that |
4751 | * we don't have concurrent modification by hardware |
4752 | * followed by an update. |
4753 | */ |
4754 | if (unlikely(pte_none(ptep_get(vmf->pte)))) |
4755 | ret = VM_FAULT_SIGBUS; |
4756 | else |
4757 | ret = VM_FAULT_NOPAGE; |
4758 | |
4759 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4760 | } |
4761 | } else if (!(vmf->flags & FAULT_FLAG_WRITE)) |
4762 | ret = do_read_fault(vmf); |
4763 | else if (!(vma->vm_flags & VM_SHARED)) |
4764 | ret = do_cow_fault(vmf); |
4765 | else |
4766 | ret = do_shared_fault(vmf); |
4767 | |
4768 | /* preallocated pagetable is unused: free it */ |
4769 | if (vmf->prealloc_pte) { |
4770 | pte_free(mm: vm_mm, pte_page: vmf->prealloc_pte); |
4771 | vmf->prealloc_pte = NULL; |
4772 | } |
4773 | return ret; |
4774 | } |
4775 | |
4776 | int numa_migrate_prep(struct folio *folio, struct vm_area_struct *vma, |
4777 | unsigned long addr, int page_nid, int *flags) |
4778 | { |
4779 | folio_get(folio); |
4780 | |
4781 | /* Record the current PID acceesing VMA */ |
4782 | vma_set_access_pid_bit(vma); |
4783 | |
4784 | count_vm_numa_event(NUMA_HINT_FAULTS); |
4785 | if (page_nid == numa_node_id()) { |
4786 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
4787 | *flags |= TNF_FAULT_LOCAL; |
4788 | } |
4789 | |
4790 | return mpol_misplaced(folio, vma, addr); |
4791 | } |
4792 | |
4793 | static vm_fault_t do_numa_page(struct vm_fault *vmf) |
4794 | { |
4795 | struct vm_area_struct *vma = vmf->vma; |
4796 | struct folio *folio = NULL; |
4797 | int nid = NUMA_NO_NODE; |
4798 | bool writable = false; |
4799 | int last_cpupid; |
4800 | int target_nid; |
4801 | pte_t pte, old_pte; |
4802 | int flags = 0; |
4803 | |
4804 | /* |
4805 | * The "pte" at this point cannot be used safely without |
4806 | * validation through pte_unmap_same(). It's of NUMA type but |
4807 | * the pfn may be screwed if the read is non atomic. |
4808 | */ |
4809 | spin_lock(lock: vmf->ptl); |
4810 | if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
4811 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4812 | goto out; |
4813 | } |
4814 | |
4815 | /* Get the normal PTE */ |
4816 | old_pte = ptep_get(ptep: vmf->pte); |
4817 | pte = pte_modify(pte: old_pte, newprot: vma->vm_page_prot); |
4818 | |
4819 | /* |
4820 | * Detect now whether the PTE could be writable; this information |
4821 | * is only valid while holding the PT lock. |
4822 | */ |
4823 | writable = pte_write(pte); |
4824 | if (!writable && vma_wants_manual_pte_write_upgrade(vma) && |
4825 | can_change_pte_writable(vma, addr: vmf->address, pte)) |
4826 | writable = true; |
4827 | |
4828 | folio = vm_normal_folio(vma, addr: vmf->address, pte); |
4829 | if (!folio || folio_is_zone_device(folio)) |
4830 | goto out_map; |
4831 | |
4832 | /* TODO: handle PTE-mapped THP */ |
4833 | if (folio_test_large(folio)) |
4834 | goto out_map; |
4835 | |
4836 | /* |
4837 | * Avoid grouping on RO pages in general. RO pages shouldn't hurt as |
4838 | * much anyway since they can be in shared cache state. This misses |
4839 | * the case where a mapping is writable but the process never writes |
4840 | * to it but pte_write gets cleared during protection updates and |
4841 | * pte_dirty has unpredictable behaviour between PTE scan updates, |
4842 | * background writeback, dirty balancing and application behaviour. |
4843 | */ |
4844 | if (!writable) |
4845 | flags |= TNF_NO_GROUP; |
4846 | |
4847 | /* |
4848 | * Flag if the folio is shared between multiple address spaces. This |
4849 | * is later used when determining whether to group tasks together |
4850 | */ |
4851 | if (folio_estimated_sharers(folio) > 1 && (vma->vm_flags & VM_SHARED)) |
4852 | flags |= TNF_SHARED; |
4853 | |
4854 | nid = folio_nid(folio); |
4855 | /* |
4856 | * For memory tiering mode, cpupid of slow memory page is used |
4857 | * to record page access time. So use default value. |
4858 | */ |
4859 | if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) && |
4860 | !node_is_toptier(node: nid)) |
4861 | last_cpupid = (-1 & LAST_CPUPID_MASK); |
4862 | else |
4863 | last_cpupid = folio_last_cpupid(folio); |
4864 | target_nid = numa_migrate_prep(folio, vma, addr: vmf->address, page_nid: nid, flags: &flags); |
4865 | if (target_nid == NUMA_NO_NODE) { |
4866 | folio_put(folio); |
4867 | goto out_map; |
4868 | } |
4869 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4870 | writable = false; |
4871 | |
4872 | /* Migrate to the requested node */ |
4873 | if (migrate_misplaced_folio(folio, vma, node: target_nid)) { |
4874 | nid = target_nid; |
4875 | flags |= TNF_MIGRATED; |
4876 | } else { |
4877 | flags |= TNF_MIGRATE_FAIL; |
4878 | vmf->pte = pte_offset_map_lock(mm: vma->vm_mm, pmd: vmf->pmd, |
4879 | addr: vmf->address, ptlp: &vmf->ptl); |
4880 | if (unlikely(!vmf->pte)) |
4881 | goto out; |
4882 | if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
4883 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4884 | goto out; |
4885 | } |
4886 | goto out_map; |
4887 | } |
4888 | |
4889 | out: |
4890 | if (nid != NUMA_NO_NODE) |
4891 | task_numa_fault(last_node: last_cpupid, node: nid, pages: 1, flags); |
4892 | return 0; |
4893 | out_map: |
4894 | /* |
4895 | * Make it present again, depending on how arch implements |
4896 | * non-accessible ptes, some can allow access by kernel mode. |
4897 | */ |
4898 | old_pte = ptep_modify_prot_start(vma, addr: vmf->address, ptep: vmf->pte); |
4899 | pte = pte_modify(pte: old_pte, newprot: vma->vm_page_prot); |
4900 | pte = pte_mkyoung(pte); |
4901 | if (writable) |
4902 | pte = pte_mkwrite(pte, vma); |
4903 | ptep_modify_prot_commit(vma, addr: vmf->address, ptep: vmf->pte, old_pte, pte); |
4904 | update_mmu_cache_range(vmf, vma, addr: vmf->address, ptep: vmf->pte, nr: 1); |
4905 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
4906 | goto out; |
4907 | } |
4908 | |
4909 | static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) |
4910 | { |
4911 | struct vm_area_struct *vma = vmf->vma; |
4912 | if (vma_is_anonymous(vma)) |
4913 | return do_huge_pmd_anonymous_page(vmf); |
4914 | if (vma->vm_ops->huge_fault) |
4915 | return vma->vm_ops->huge_fault(vmf, PMD_ORDER); |
4916 | return VM_FAULT_FALLBACK; |
4917 | } |
4918 | |
4919 | /* `inline' is required to avoid gcc 4.1.2 build error */ |
4920 | static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) |
4921 | { |
4922 | struct vm_area_struct *vma = vmf->vma; |
4923 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
4924 | vm_fault_t ret; |
4925 | |
4926 | if (vma_is_anonymous(vma)) { |
4927 | if (likely(!unshare) && |
4928 | userfaultfd_huge_pmd_wp(vma, pmd: vmf->orig_pmd)) { |
4929 | if (userfaultfd_wp_async(vma: vmf->vma)) |
4930 | goto split; |
4931 | return handle_userfault(vmf, VM_UFFD_WP); |
4932 | } |
4933 | return do_huge_pmd_wp_page(vmf); |
4934 | } |
4935 | |
4936 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { |
4937 | if (vma->vm_ops->huge_fault) { |
4938 | ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER); |
4939 | if (!(ret & VM_FAULT_FALLBACK)) |
4940 | return ret; |
4941 | } |
4942 | } |
4943 | |
4944 | split: |
4945 | /* COW or write-notify handled on pte level: split pmd. */ |
4946 | __split_huge_pmd(vma, pmd: vmf->pmd, address: vmf->address, freeze: false, NULL); |
4947 | |
4948 | return VM_FAULT_FALLBACK; |
4949 | } |
4950 | |
4951 | static vm_fault_t create_huge_pud(struct vm_fault *vmf) |
4952 | { |
4953 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ |
4954 | defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) |
4955 | struct vm_area_struct *vma = vmf->vma; |
4956 | /* No support for anonymous transparent PUD pages yet */ |
4957 | if (vma_is_anonymous(vma)) |
4958 | return VM_FAULT_FALLBACK; |
4959 | if (vma->vm_ops->huge_fault) |
4960 | return vma->vm_ops->huge_fault(vmf, PUD_ORDER); |
4961 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
4962 | return VM_FAULT_FALLBACK; |
4963 | } |
4964 | |
4965 | static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) |
4966 | { |
4967 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ |
4968 | defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) |
4969 | struct vm_area_struct *vma = vmf->vma; |
4970 | vm_fault_t ret; |
4971 | |
4972 | /* No support for anonymous transparent PUD pages yet */ |
4973 | if (vma_is_anonymous(vma)) |
4974 | goto split; |
4975 | if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { |
4976 | if (vma->vm_ops->huge_fault) { |
4977 | ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER); |
4978 | if (!(ret & VM_FAULT_FALLBACK)) |
4979 | return ret; |
4980 | } |
4981 | } |
4982 | split: |
4983 | /* COW or write-notify not handled on PUD level: split pud.*/ |
4984 | __split_huge_pud(vma, pud: vmf->pud, address: vmf->address); |
4985 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
4986 | return VM_FAULT_FALLBACK; |
4987 | } |
4988 | |
4989 | /* |
4990 | * These routines also need to handle stuff like marking pages dirty |
4991 | * and/or accessed for architectures that don't do it in hardware (most |
4992 | * RISC architectures). The early dirtying is also good on the i386. |
4993 | * |
4994 | * There is also a hook called "update_mmu_cache()" that architectures |
4995 | * with external mmu caches can use to update those (ie the Sparc or |
4996 | * PowerPC hashed page tables that act as extended TLBs). |
4997 | * |
4998 | * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow |
4999 | * concurrent faults). |
5000 | * |
5001 | * The mmap_lock may have been released depending on flags and our return value. |
5002 | * See filemap_fault() and __folio_lock_or_retry(). |
5003 | */ |
5004 | static vm_fault_t handle_pte_fault(struct vm_fault *vmf) |
5005 | { |
5006 | pte_t entry; |
5007 | |
5008 | if (unlikely(pmd_none(*vmf->pmd))) { |
5009 | /* |
5010 | * Leave __pte_alloc() until later: because vm_ops->fault may |
5011 | * want to allocate huge page, and if we expose page table |
5012 | * for an instant, it will be difficult to retract from |
5013 | * concurrent faults and from rmap lookups. |
5014 | */ |
5015 | vmf->pte = NULL; |
5016 | vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID; |
5017 | } else { |
5018 | /* |
5019 | * A regular pmd is established and it can't morph into a huge |
5020 | * pmd by anon khugepaged, since that takes mmap_lock in write |
5021 | * mode; but shmem or file collapse to THP could still morph |
5022 | * it into a huge pmd: just retry later if so. |
5023 | */ |
5024 | vmf->pte = pte_offset_map_nolock(mm: vmf->vma->vm_mm, pmd: vmf->pmd, |
5025 | addr: vmf->address, ptlp: &vmf->ptl); |
5026 | if (unlikely(!vmf->pte)) |
5027 | return 0; |
5028 | vmf->orig_pte = ptep_get_lockless(ptep: vmf->pte); |
5029 | vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; |
5030 | |
5031 | if (pte_none(pte: vmf->orig_pte)) { |
5032 | pte_unmap(pte: vmf->pte); |
5033 | vmf->pte = NULL; |
5034 | } |
5035 | } |
5036 | |
5037 | if (!vmf->pte) |
5038 | return do_pte_missing(vmf); |
5039 | |
5040 | if (!pte_present(a: vmf->orig_pte)) |
5041 | return do_swap_page(vmf); |
5042 | |
5043 | if (pte_protnone(pte: vmf->orig_pte) && vma_is_accessible(vma: vmf->vma)) |
5044 | return do_numa_page(vmf); |
5045 | |
5046 | spin_lock(lock: vmf->ptl); |
5047 | entry = vmf->orig_pte; |
5048 | if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) { |
5049 | update_mmu_tlb(vma: vmf->vma, address: vmf->address, ptep: vmf->pte); |
5050 | goto unlock; |
5051 | } |
5052 | if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { |
5053 | if (!pte_write(pte: entry)) |
5054 | return do_wp_page(vmf); |
5055 | else if (likely(vmf->flags & FAULT_FLAG_WRITE)) |
5056 | entry = pte_mkdirty(pte: entry); |
5057 | } |
5058 | entry = pte_mkyoung(pte: entry); |
5059 | if (ptep_set_access_flags(vma: vmf->vma, address: vmf->address, ptep: vmf->pte, entry, |
5060 | dirty: vmf->flags & FAULT_FLAG_WRITE)) { |
5061 | update_mmu_cache_range(vmf, vma: vmf->vma, addr: vmf->address, |
5062 | ptep: vmf->pte, nr: 1); |
5063 | } else { |
5064 | /* Skip spurious TLB flush for retried page fault */ |
5065 | if (vmf->flags & FAULT_FLAG_TRIED) |
5066 | goto unlock; |
5067 | /* |
5068 | * This is needed only for protection faults but the arch code |
5069 | * is not yet telling us if this is a protection fault or not. |
5070 | * This still avoids useless tlb flushes for .text page faults |
5071 | * with threads. |
5072 | */ |
5073 | if (vmf->flags & FAULT_FLAG_WRITE) |
5074 | flush_tlb_fix_spurious_fault(vmf->vma, vmf->address, |
5075 | vmf->pte); |
5076 | } |
5077 | unlock: |
5078 | pte_unmap_unlock(vmf->pte, vmf->ptl); |
5079 | return 0; |
5080 | } |
5081 | |
5082 | /* |
5083 | * On entry, we hold either the VMA lock or the mmap_lock |
5084 | * (FAULT_FLAG_VMA_LOCK tells you which). If VM_FAULT_RETRY is set in |
5085 | * the result, the mmap_lock is not held on exit. See filemap_fault() |
5086 | * and __folio_lock_or_retry(). |
5087 | */ |
5088 | static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, |
5089 | unsigned long address, unsigned int flags) |
5090 | { |
5091 | struct vm_fault vmf = { |
5092 | .vma = vma, |
5093 | .address = address & PAGE_MASK, |
5094 | .real_address = address, |
5095 | .flags = flags, |
5096 | .pgoff = linear_page_index(vma, address), |
5097 | .gfp_mask = __get_fault_gfp_mask(vma), |
5098 | }; |
5099 | struct mm_struct *mm = vma->vm_mm; |
5100 | unsigned long vm_flags = vma->vm_flags; |
5101 | pgd_t *pgd; |
5102 | p4d_t *p4d; |
5103 | vm_fault_t ret; |
5104 | |
5105 | pgd = pgd_offset(mm, address); |
5106 | p4d = p4d_alloc(mm, pgd, address); |
5107 | if (!p4d) |
5108 | return VM_FAULT_OOM; |
5109 | |
5110 | vmf.pud = pud_alloc(mm, p4d, address); |
5111 | if (!vmf.pud) |
5112 | return VM_FAULT_OOM; |
5113 | retry_pud: |
5114 | if (pud_none(pud: *vmf.pud) && |
5115 | hugepage_vma_check(vma, vm_flags, smaps: false, in_pf: true, enforce_sysfs: true)) { |
5116 | ret = create_huge_pud(vmf: &vmf); |
5117 | if (!(ret & VM_FAULT_FALLBACK)) |
5118 | return ret; |
5119 | } else { |
5120 | pud_t orig_pud = *vmf.pud; |
5121 | |
5122 | barrier(); |
5123 | if (pud_trans_huge(pud: orig_pud) || pud_devmap(pud: orig_pud)) { |
5124 | |
5125 | /* |
5126 | * TODO once we support anonymous PUDs: NUMA case and |
5127 | * FAULT_FLAG_UNSHARE handling. |
5128 | */ |
5129 | if ((flags & FAULT_FLAG_WRITE) && !pud_write(pud: orig_pud)) { |
5130 | ret = wp_huge_pud(vmf: &vmf, orig_pud); |
5131 | if (!(ret & VM_FAULT_FALLBACK)) |
5132 | return ret; |
5133 | } else { |
5134 | huge_pud_set_accessed(vmf: &vmf, orig_pud); |
5135 | return 0; |
5136 | } |
5137 | } |
5138 | } |
5139 | |
5140 | vmf.pmd = pmd_alloc(mm, pud: vmf.pud, address); |
5141 | if (!vmf.pmd) |
5142 | return VM_FAULT_OOM; |
5143 | |
5144 | /* Huge pud page fault raced with pmd_alloc? */ |
5145 | if (pud_trans_unstable(pud: vmf.pud)) |
5146 | goto retry_pud; |
5147 | |
5148 | if (pmd_none(pmd: *vmf.pmd) && |
5149 | hugepage_vma_check(vma, vm_flags, smaps: false, in_pf: true, enforce_sysfs: true)) { |
5150 | ret = create_huge_pmd(vmf: &vmf); |
5151 | if (!(ret & VM_FAULT_FALLBACK)) |
5152 | return ret; |
5153 | } else { |
5154 | vmf.orig_pmd = pmdp_get_lockless(pmdp: vmf.pmd); |
5155 | |
5156 | if (unlikely(is_swap_pmd(vmf.orig_pmd))) { |
5157 | VM_BUG_ON(thp_migration_supported() && |
5158 | !is_pmd_migration_entry(vmf.orig_pmd)); |
5159 | if (is_pmd_migration_entry(pmd: vmf.orig_pmd)) |
5160 | pmd_migration_entry_wait(mm, pmd: vmf.pmd); |
5161 | return 0; |
5162 | } |
5163 | if (pmd_trans_huge(pmd: vmf.orig_pmd) || pmd_devmap(pmd: vmf.orig_pmd)) { |
5164 | if (pmd_protnone(pmd: vmf.orig_pmd) && vma_is_accessible(vma)) |
5165 | return do_huge_pmd_numa_page(vmf: &vmf); |
5166 | |
5167 | if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) && |
5168 | !pmd_write(pmd: vmf.orig_pmd)) { |
5169 | ret = wp_huge_pmd(vmf: &vmf); |
5170 | if (!(ret & VM_FAULT_FALLBACK)) |
5171 | return ret; |
5172 | } else { |
5173 | huge_pmd_set_accessed(vmf: &vmf); |
5174 | return 0; |
5175 | } |
5176 | } |
5177 | } |
5178 | |
5179 | return handle_pte_fault(vmf: &vmf); |
5180 | } |
5181 | |
5182 | /** |
5183 | * mm_account_fault - Do page fault accounting |
5184 | * @mm: mm from which memcg should be extracted. It can be NULL. |
5185 | * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting |
5186 | * of perf event counters, but we'll still do the per-task accounting to |
5187 | * the task who triggered this page fault. |
5188 | * @address: the faulted address. |
5189 | * @flags: the fault flags. |
5190 | * @ret: the fault retcode. |
5191 | * |
5192 | * This will take care of most of the page fault accounting. Meanwhile, it |
5193 | * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter |
5194 | * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should |
5195 | * still be in per-arch page fault handlers at the entry of page fault. |
5196 | */ |
5197 | static inline void mm_account_fault(struct mm_struct *mm, struct pt_regs *regs, |
5198 | unsigned long address, unsigned int flags, |
5199 | vm_fault_t ret) |
5200 | { |
5201 | bool major; |
5202 | |
5203 | /* Incomplete faults will be accounted upon completion. */ |
5204 | if (ret & VM_FAULT_RETRY) |
5205 | return; |
5206 | |
5207 | /* |
5208 | * To preserve the behavior of older kernels, PGFAULT counters record |
5209 | * both successful and failed faults, as opposed to perf counters, |
5210 | * which ignore failed cases. |
5211 | */ |
5212 | count_vm_event(item: PGFAULT); |
5213 | count_memcg_event_mm(mm, idx: PGFAULT); |
5214 | |
5215 | /* |
5216 | * Do not account for unsuccessful faults (e.g. when the address wasn't |
5217 | * valid). That includes arch_vma_access_permitted() failing before |
5218 | * reaching here. So this is not a "this many hardware page faults" |
5219 | * counter. We should use the hw profiling for that. |
5220 | */ |
5221 | if (ret & VM_FAULT_ERROR) |
5222 | return; |
5223 | |
5224 | /* |
5225 | * We define the fault as a major fault when the final successful fault |
5226 | * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't |
5227 | * handle it immediately previously). |
5228 | */ |
5229 | major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED); |
5230 | |
5231 | if (major) |
5232 | current->maj_flt++; |
5233 | else |
5234 | current->min_flt++; |
5235 | |
5236 | /* |
5237 | * If the fault is done for GUP, regs will be NULL. We only do the |
5238 | * accounting for the per thread fault counters who triggered the |
5239 | * fault, and we skip the perf event updates. |
5240 | */ |
5241 | if (!regs) |
5242 | return; |
5243 | |
5244 | if (major) |
5245 | perf_sw_event(event_id: PERF_COUNT_SW_PAGE_FAULTS_MAJ, nr: 1, regs, addr: address); |
5246 | else |
5247 | perf_sw_event(event_id: PERF_COUNT_SW_PAGE_FAULTS_MIN, nr: 1, regs, addr: address); |
5248 | } |
5249 | |
5250 | #ifdef CONFIG_LRU_GEN |
5251 | static void lru_gen_enter_fault(struct vm_area_struct *vma) |
5252 | { |
5253 | /* the LRU algorithm only applies to accesses with recency */ |
5254 | current->in_lru_fault = vma_has_recency(vma); |
5255 | } |
5256 | |
5257 | static void lru_gen_exit_fault(void) |
5258 | { |
5259 | current->in_lru_fault = false; |
5260 | } |
5261 | #else |
5262 | static void lru_gen_enter_fault(struct vm_area_struct *vma) |
5263 | { |
5264 | } |
5265 | |
5266 | static void lru_gen_exit_fault(void) |
5267 | { |
5268 | } |
5269 | #endif /* CONFIG_LRU_GEN */ |
5270 | |
5271 | static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma, |
5272 | unsigned int *flags) |
5273 | { |
5274 | if (unlikely(*flags & FAULT_FLAG_UNSHARE)) { |
5275 | if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE)) |
5276 | return VM_FAULT_SIGSEGV; |
5277 | /* |
5278 | * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's |
5279 | * just treat it like an ordinary read-fault otherwise. |
5280 | */ |
5281 | if (!is_cow_mapping(flags: vma->vm_flags)) |
5282 | *flags &= ~FAULT_FLAG_UNSHARE; |
5283 | } else if (*flags & FAULT_FLAG_WRITE) { |
5284 | /* Write faults on read-only mappings are impossible ... */ |
5285 | if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE))) |
5286 | return VM_FAULT_SIGSEGV; |
5287 | /* ... and FOLL_FORCE only applies to COW mappings. */ |
5288 | if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) && |
5289 | !is_cow_mapping(vma->vm_flags))) |
5290 | return VM_FAULT_SIGSEGV; |
5291 | } |
5292 | #ifdef CONFIG_PER_VMA_LOCK |
5293 | /* |
5294 | * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of |
5295 | * the assumption that lock is dropped on VM_FAULT_RETRY. |
5296 | */ |
5297 | if (WARN_ON_ONCE((*flags & |
5298 | (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) == |
5299 | (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT))) |
5300 | return VM_FAULT_SIGSEGV; |
5301 | #endif |
5302 | |
5303 | return 0; |
5304 | } |
5305 | |
5306 | /* |
5307 | * By the time we get here, we already hold the mm semaphore |
5308 | * |
5309 | * The mmap_lock may have been released depending on flags and our |
5310 | * return value. See filemap_fault() and __folio_lock_or_retry(). |
5311 | */ |
5312 | vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, |
5313 | unsigned int flags, struct pt_regs *regs) |
5314 | { |
5315 | /* If the fault handler drops the mmap_lock, vma may be freed */ |
5316 | struct mm_struct *mm = vma->vm_mm; |
5317 | vm_fault_t ret; |
5318 | |
5319 | __set_current_state(TASK_RUNNING); |
5320 | |
5321 | ret = sanitize_fault_flags(vma, flags: &flags); |
5322 | if (ret) |
5323 | goto out; |
5324 | |
5325 | if (!arch_vma_access_permitted(vma, write: flags & FAULT_FLAG_WRITE, |
5326 | execute: flags & FAULT_FLAG_INSTRUCTION, |
5327 | foreign: flags & FAULT_FLAG_REMOTE)) { |
5328 | ret = VM_FAULT_SIGSEGV; |
5329 | goto out; |
5330 | } |
5331 | |
5332 | /* |
5333 | * Enable the memcg OOM handling for faults triggered in user |
5334 | * space. Kernel faults are handled more gracefully. |
5335 | */ |
5336 | if (flags & FAULT_FLAG_USER) |
5337 | mem_cgroup_enter_user_fault(); |
5338 | |
5339 | lru_gen_enter_fault(vma); |
5340 | |
5341 | if (unlikely(is_vm_hugetlb_page(vma))) |
5342 | ret = hugetlb_fault(mm: vma->vm_mm, vma, address, flags); |
5343 | else |
5344 | ret = __handle_mm_fault(vma, address, flags); |
5345 | |
5346 | lru_gen_exit_fault(); |
5347 | |
5348 | if (flags & FAULT_FLAG_USER) { |
5349 | mem_cgroup_exit_user_fault(); |
5350 | /* |
5351 | * The task may have entered a memcg OOM situation but |
5352 | * if the allocation error was handled gracefully (no |
5353 | * VM_FAULT_OOM), there is no need to kill anything. |
5354 | * Just clean up the OOM state peacefully. |
5355 | */ |
5356 | if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) |
5357 | mem_cgroup_oom_synchronize(wait: false); |
5358 | } |
5359 | out: |
5360 | mm_account_fault(mm, regs, address, flags, ret); |
5361 | |
5362 | return ret; |
5363 | } |
5364 | EXPORT_SYMBOL_GPL(handle_mm_fault); |
5365 | |
5366 | #ifdef CONFIG_LOCK_MM_AND_FIND_VMA |
5367 | #include <linux/extable.h> |
5368 | |
5369 | static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs) |
5370 | { |
5371 | if (likely(mmap_read_trylock(mm))) |
5372 | return true; |
5373 | |
5374 | if (regs && !user_mode(regs)) { |
5375 | unsigned long ip = instruction_pointer(regs); |
5376 | if (!search_exception_tables(add: ip)) |
5377 | return false; |
5378 | } |
5379 | |
5380 | return !mmap_read_lock_killable(mm); |
5381 | } |
5382 | |
5383 | static inline bool mmap_upgrade_trylock(struct mm_struct *mm) |
5384 | { |
5385 | /* |
5386 | * We don't have this operation yet. |
5387 | * |
5388 | * It should be easy enough to do: it's basically a |
5389 | * atomic_long_try_cmpxchg_acquire() |
5390 | * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but |
5391 | * it also needs the proper lockdep magic etc. |
5392 | */ |
5393 | return false; |
5394 | } |
5395 | |
5396 | static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs) |
5397 | { |
5398 | mmap_read_unlock(mm); |
5399 | if (regs && !user_mode(regs)) { |
5400 | unsigned long ip = instruction_pointer(regs); |
5401 | if (!search_exception_tables(add: ip)) |
5402 | return false; |
5403 | } |
5404 | return !mmap_write_lock_killable(mm); |
5405 | } |
5406 | |
5407 | /* |
5408 | * Helper for page fault handling. |
5409 | * |
5410 | * This is kind of equivalend to "mmap_read_lock()" followed |
5411 | * by "find_extend_vma()", except it's a lot more careful about |
5412 | * the locking (and will drop the lock on failure). |
5413 | * |
5414 | * For example, if we have a kernel bug that causes a page |
5415 | * fault, we don't want to just use mmap_read_lock() to get |
5416 | * the mm lock, because that would deadlock if the bug were |
5417 | * to happen while we're holding the mm lock for writing. |
5418 | * |
5419 | * So this checks the exception tables on kernel faults in |
5420 | * order to only do this all for instructions that are actually |
5421 | * expected to fault. |
5422 | * |
5423 | * We can also actually take the mm lock for writing if we |
5424 | * need to extend the vma, which helps the VM layer a lot. |
5425 | */ |
5426 | struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, |
5427 | unsigned long addr, struct pt_regs *regs) |
5428 | { |
5429 | struct vm_area_struct *vma; |
5430 | |
5431 | if (!get_mmap_lock_carefully(mm, regs)) |
5432 | return NULL; |
5433 | |
5434 | vma = find_vma(mm, addr); |
5435 | if (likely(vma && (vma->vm_start <= addr))) |
5436 | return vma; |
5437 | |
5438 | /* |
5439 | * Well, dang. We might still be successful, but only |
5440 | * if we can extend a vma to do so. |
5441 | */ |
5442 | if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) { |
5443 | mmap_read_unlock(mm); |
5444 | return NULL; |
5445 | } |
5446 | |
5447 | /* |
5448 | * We can try to upgrade the mmap lock atomically, |
5449 | * in which case we can continue to use the vma |
5450 | * we already looked up. |
5451 | * |
5452 | * Otherwise we'll have to drop the mmap lock and |
5453 | * re-take it, and also look up the vma again, |
5454 | * re-checking it. |
5455 | */ |
5456 | if (!mmap_upgrade_trylock(mm)) { |
5457 | if (!upgrade_mmap_lock_carefully(mm, regs)) |
5458 | return NULL; |
5459 | |
5460 | vma = find_vma(mm, addr); |
5461 | if (!vma) |
5462 | goto fail; |
5463 | if (vma->vm_start <= addr) |
5464 | goto success; |
5465 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
5466 | goto fail; |
5467 | } |
5468 | |
5469 | if (expand_stack_locked(vma, address: addr)) |
5470 | goto fail; |
5471 | |
5472 | success: |
5473 | mmap_write_downgrade(mm); |
5474 | return vma; |
5475 | |
5476 | fail: |
5477 | mmap_write_unlock(mm); |
5478 | return NULL; |
5479 | } |
5480 | #endif |
5481 | |
5482 | #ifdef CONFIG_PER_VMA_LOCK |
5483 | /* |
5484 | * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be |
5485 | * stable and not isolated. If the VMA is not found or is being modified the |
5486 | * function returns NULL. |
5487 | */ |
5488 | struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, |
5489 | unsigned long address) |
5490 | { |
5491 | MA_STATE(mas, &mm->mm_mt, address, address); |
5492 | struct vm_area_struct *vma; |
5493 | |
5494 | rcu_read_lock(); |
5495 | retry: |
5496 | vma = mas_walk(mas: &mas); |
5497 | if (!vma) |
5498 | goto inval; |
5499 | |
5500 | if (!vma_start_read(vma)) |
5501 | goto inval; |
5502 | |
5503 | /* |
5504 | * find_mergeable_anon_vma uses adjacent vmas which are not locked. |
5505 | * This check must happen after vma_start_read(); otherwise, a |
5506 | * concurrent mremap() with MREMAP_DONTUNMAP could dissociate the VMA |
5507 | * from its anon_vma. |
5508 | */ |
5509 | if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) |
5510 | goto inval_end_read; |
5511 | |
5512 | /* Check since vm_start/vm_end might change before we lock the VMA */ |
5513 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) |
5514 | goto inval_end_read; |
5515 | |
5516 | /* Check if the VMA got isolated after we found it */ |
5517 | if (vma->detached) { |
5518 | vma_end_read(vma); |
5519 | count_vm_vma_lock_event(VMA_LOCK_MISS); |
5520 | /* The area was replaced with another one */ |
5521 | goto retry; |
5522 | } |
5523 | |
5524 | rcu_read_unlock(); |
5525 | return vma; |
5526 | |
5527 | inval_end_read: |
5528 | vma_end_read(vma); |
5529 | inval: |
5530 | rcu_read_unlock(); |
5531 | count_vm_vma_lock_event(VMA_LOCK_ABORT); |
5532 | return NULL; |
5533 | } |
5534 | #endif /* CONFIG_PER_VMA_LOCK */ |
5535 | |
5536 | #ifndef __PAGETABLE_P4D_FOLDED |
5537 | /* |
5538 | * Allocate p4d page table. |
5539 | * We've already handled the fast-path in-line. |
5540 | */ |
5541 | int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
5542 | { |
5543 | p4d_t *new = p4d_alloc_one(mm, addr: address); |
5544 | if (!new) |
5545 | return -ENOMEM; |
5546 | |
5547 | spin_lock(lock: &mm->page_table_lock); |
5548 | if (pgd_present(pgd: *pgd)) { /* Another has populated it */ |
5549 | p4d_free(mm, p4d: new); |
5550 | } else { |
5551 | smp_wmb(); /* See comment in pmd_install() */ |
5552 | pgd_populate(mm, pgd, p4d: new); |
5553 | } |
5554 | spin_unlock(lock: &mm->page_table_lock); |
5555 | return 0; |
5556 | } |
5557 | #endif /* __PAGETABLE_P4D_FOLDED */ |
5558 | |
5559 | #ifndef __PAGETABLE_PUD_FOLDED |
5560 | /* |
5561 | * Allocate page upper directory. |
5562 | * We've already handled the fast-path in-line. |
5563 | */ |
5564 | int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) |
5565 | { |
5566 | pud_t *new = pud_alloc_one(mm, addr: address); |
5567 | if (!new) |
5568 | return -ENOMEM; |
5569 | |
5570 | spin_lock(lock: &mm->page_table_lock); |
5571 | if (!p4d_present(p4d: *p4d)) { |
5572 | mm_inc_nr_puds(mm); |
5573 | smp_wmb(); /* See comment in pmd_install() */ |
5574 | p4d_populate(mm, p4d, pud: new); |
5575 | } else /* Another has populated it */ |
5576 | pud_free(mm, pud: new); |
5577 | spin_unlock(lock: &mm->page_table_lock); |
5578 | return 0; |
5579 | } |
5580 | #endif /* __PAGETABLE_PUD_FOLDED */ |
5581 | |
5582 | #ifndef __PAGETABLE_PMD_FOLDED |
5583 | /* |
5584 | * Allocate page middle directory. |
5585 | * We've already handled the fast-path in-line. |
5586 | */ |
5587 | int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
5588 | { |
5589 | spinlock_t *ptl; |
5590 | pmd_t *new = pmd_alloc_one(mm, addr: address); |
5591 | if (!new) |
5592 | return -ENOMEM; |
5593 | |
5594 | ptl = pud_lock(mm, pud); |
5595 | if (!pud_present(pud: *pud)) { |
5596 | mm_inc_nr_pmds(mm); |
5597 | smp_wmb(); /* See comment in pmd_install() */ |
5598 | pud_populate(mm, pud, pmd: new); |
5599 | } else { /* Another has populated it */ |
5600 | pmd_free(mm, pmd: new); |
5601 | } |
5602 | spin_unlock(lock: ptl); |
5603 | return 0; |
5604 | } |
5605 | #endif /* __PAGETABLE_PMD_FOLDED */ |
5606 | |
5607 | /** |
5608 | * follow_pte - look up PTE at a user virtual address |
5609 | * @mm: the mm_struct of the target address space |
5610 | * @address: user virtual address |
5611 | * @ptepp: location to store found PTE |
5612 | * @ptlp: location to store the lock for the PTE |
5613 | * |
5614 | * On a successful return, the pointer to the PTE is stored in @ptepp; |
5615 | * the corresponding lock is taken and its location is stored in @ptlp. |
5616 | * The contents of the PTE are only stable until @ptlp is released; |
5617 | * any further use, if any, must be protected against invalidation |
5618 | * with MMU notifiers. |
5619 | * |
5620 | * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore |
5621 | * should be taken for read. |
5622 | * |
5623 | * KVM uses this function. While it is arguably less bad than ``follow_pfn``, |
5624 | * it is not a good general-purpose API. |
5625 | * |
5626 | * Return: zero on success, -ve otherwise. |
5627 | */ |
5628 | int follow_pte(struct mm_struct *mm, unsigned long address, |
5629 | pte_t **ptepp, spinlock_t **ptlp) |
5630 | { |
5631 | pgd_t *pgd; |
5632 | p4d_t *p4d; |
5633 | pud_t *pud; |
5634 | pmd_t *pmd; |
5635 | pte_t *ptep; |
5636 | |
5637 | pgd = pgd_offset(mm, address); |
5638 | if (pgd_none(pgd: *pgd) || unlikely(pgd_bad(*pgd))) |
5639 | goto out; |
5640 | |
5641 | p4d = p4d_offset(pgd, address); |
5642 | if (p4d_none(p4d: *p4d) || unlikely(p4d_bad(*p4d))) |
5643 | goto out; |
5644 | |
5645 | pud = pud_offset(p4d, address); |
5646 | if (pud_none(pud: *pud) || unlikely(pud_bad(*pud))) |
5647 | goto out; |
5648 | |
5649 | pmd = pmd_offset(pud, address); |
5650 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
5651 | |
5652 | ptep = pte_offset_map_lock(mm, pmd, addr: address, ptlp); |
5653 | if (!ptep) |
5654 | goto out; |
5655 | if (!pte_present(a: ptep_get(ptep))) |
5656 | goto unlock; |
5657 | *ptepp = ptep; |
5658 | return 0; |
5659 | unlock: |
5660 | pte_unmap_unlock(ptep, *ptlp); |
5661 | out: |
5662 | return -EINVAL; |
5663 | } |
5664 | EXPORT_SYMBOL_GPL(follow_pte); |
5665 | |
5666 | /** |
5667 | * follow_pfn - look up PFN at a user virtual address |
5668 | * @vma: memory mapping |
5669 | * @address: user virtual address |
5670 | * @pfn: location to store found PFN |
5671 | * |
5672 | * Only IO mappings and raw PFN mappings are allowed. |
5673 | * |
5674 | * This function does not allow the caller to read the permissions |
5675 | * of the PTE. Do not use it. |
5676 | * |
5677 | * Return: zero and the pfn at @pfn on success, -ve otherwise. |
5678 | */ |
5679 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
5680 | unsigned long *pfn) |
5681 | { |
5682 | int ret = -EINVAL; |
5683 | spinlock_t *ptl; |
5684 | pte_t *ptep; |
5685 | |
5686 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
5687 | return ret; |
5688 | |
5689 | ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); |
5690 | if (ret) |
5691 | return ret; |
5692 | *pfn = pte_pfn(pte: ptep_get(ptep)); |
5693 | pte_unmap_unlock(ptep, ptl); |
5694 | return 0; |
5695 | } |
5696 | EXPORT_SYMBOL(follow_pfn); |
5697 | |
5698 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
5699 | int follow_phys(struct vm_area_struct *vma, |
5700 | unsigned long address, unsigned int flags, |
5701 | unsigned long *prot, resource_size_t *phys) |
5702 | { |
5703 | int ret = -EINVAL; |
5704 | pte_t *ptep, pte; |
5705 | spinlock_t *ptl; |
5706 | |
5707 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
5708 | goto out; |
5709 | |
5710 | if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) |
5711 | goto out; |
5712 | pte = ptep_get(ptep); |
5713 | |
5714 | if ((flags & FOLL_WRITE) && !pte_write(pte)) |
5715 | goto unlock; |
5716 | |
5717 | *prot = pgprot_val(pte_pgprot(pte)); |
5718 | *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
5719 | |
5720 | ret = 0; |
5721 | unlock: |
5722 | pte_unmap_unlock(ptep, ptl); |
5723 | out: |
5724 | return ret; |
5725 | } |
5726 | |
5727 | /** |
5728 | * generic_access_phys - generic implementation for iomem mmap access |
5729 | * @vma: the vma to access |
5730 | * @addr: userspace address, not relative offset within @vma |
5731 | * @buf: buffer to read/write |
5732 | * @len: length of transfer |
5733 | * @write: set to FOLL_WRITE when writing, otherwise reading |
5734 | * |
5735 | * This is a generic implementation for &vm_operations_struct.access for an |
5736 | * iomem mapping. This callback is used by access_process_vm() when the @vma is |
5737 | * not page based. |
5738 | */ |
5739 | int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, |
5740 | void *buf, int len, int write) |
5741 | { |
5742 | resource_size_t phys_addr; |
5743 | unsigned long prot = 0; |
5744 | void __iomem *maddr; |
5745 | pte_t *ptep, pte; |
5746 | spinlock_t *ptl; |
5747 | int offset = offset_in_page(addr); |
5748 | int ret = -EINVAL; |
5749 | |
5750 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
5751 | return -EINVAL; |
5752 | |
5753 | retry: |
5754 | if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) |
5755 | return -EINVAL; |
5756 | pte = ptep_get(ptep); |
5757 | pte_unmap_unlock(ptep, ptl); |
5758 | |
5759 | prot = pgprot_val(pte_pgprot(pte)); |
5760 | phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
5761 | |
5762 | if ((write & FOLL_WRITE) && !pte_write(pte)) |
5763 | return -EINVAL; |
5764 | |
5765 | maddr = ioremap_prot(offset: phys_addr, PAGE_ALIGN(len + offset), prot_val: prot); |
5766 | if (!maddr) |
5767 | return -ENOMEM; |
5768 | |
5769 | if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) |
5770 | goto out_unmap; |
5771 | |
5772 | if (!pte_same(a: pte, b: ptep_get(ptep))) { |
5773 | pte_unmap_unlock(ptep, ptl); |
5774 | iounmap(addr: maddr); |
5775 | |
5776 | goto retry; |
5777 | } |
5778 | |
5779 | if (write) |
5780 | memcpy_toio(maddr + offset, buf, len); |
5781 | else |
5782 | memcpy_fromio(buf, maddr + offset, len); |
5783 | ret = len; |
5784 | pte_unmap_unlock(ptep, ptl); |
5785 | out_unmap: |
5786 | iounmap(addr: maddr); |
5787 | |
5788 | return ret; |
5789 | } |
5790 | EXPORT_SYMBOL_GPL(generic_access_phys); |
5791 | #endif |
5792 | |
5793 | /* |
5794 | * Access another process' address space as given in mm. |
5795 | */ |
5796 | static int __access_remote_vm(struct mm_struct *mm, unsigned long addr, |
5797 | void *buf, int len, unsigned int gup_flags) |
5798 | { |
5799 | void *old_buf = buf; |
5800 | int write = gup_flags & FOLL_WRITE; |
5801 | |
5802 | if (mmap_read_lock_killable(mm)) |
5803 | return 0; |
5804 | |
5805 | /* Untag the address before looking up the VMA */ |
5806 | addr = untagged_addr_remote(mm, addr); |
5807 | |
5808 | /* Avoid triggering the temporary warning in __get_user_pages */ |
5809 | if (!vma_lookup(mm, addr) && !expand_stack(mm, addr)) |
5810 | return 0; |
5811 | |
5812 | /* ignore errors, just check how much was successfully transferred */ |
5813 | while (len) { |
5814 | int bytes, offset; |
5815 | void *maddr; |
5816 | struct vm_area_struct *vma = NULL; |
5817 | struct page *page = get_user_page_vma_remote(mm, addr, |
5818 | gup_flags, vmap: &vma); |
5819 | |
5820 | if (IS_ERR(ptr: page)) { |
5821 | /* We might need to expand the stack to access it */ |
5822 | vma = vma_lookup(mm, addr); |
5823 | if (!vma) { |
5824 | vma = expand_stack(mm, addr); |
5825 | |
5826 | /* mmap_lock was dropped on failure */ |
5827 | if (!vma) |
5828 | return buf - old_buf; |
5829 | |
5830 | /* Try again if stack expansion worked */ |
5831 | continue; |
5832 | } |
5833 | |
5834 | /* |
5835 | * Check if this is a VM_IO | VM_PFNMAP VMA, which |
5836 | * we can access using slightly different code. |
5837 | */ |
5838 | bytes = 0; |
5839 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
5840 | if (vma->vm_ops && vma->vm_ops->access) |
5841 | bytes = vma->vm_ops->access(vma, addr, buf, |
5842 | len, write); |
5843 | #endif |
5844 | if (bytes <= 0) |
5845 | break; |
5846 | } else { |
5847 | bytes = len; |
5848 | offset = addr & (PAGE_SIZE-1); |
5849 | if (bytes > PAGE_SIZE-offset) |
5850 | bytes = PAGE_SIZE-offset; |
5851 | |
5852 | maddr = kmap(page); |
5853 | if (write) { |
5854 | copy_to_user_page(vma, page, addr, |
5855 | maddr + offset, buf, bytes); |
5856 | set_page_dirty_lock(page); |
5857 | } else { |
5858 | copy_from_user_page(vma, page, addr, |
5859 | buf, maddr + offset, bytes); |
5860 | } |
5861 | kunmap(page); |
5862 | put_page(page); |
5863 | } |
5864 | len -= bytes; |
5865 | buf += bytes; |
5866 | addr += bytes; |
5867 | } |
5868 | mmap_read_unlock(mm); |
5869 | |
5870 | return buf - old_buf; |
5871 | } |
5872 | |
5873 | /** |
5874 | * access_remote_vm - access another process' address space |
5875 | * @mm: the mm_struct of the target address space |
5876 | * @addr: start address to access |
5877 | * @buf: source or destination buffer |
5878 | * @len: number of bytes to transfer |
5879 | * @gup_flags: flags modifying lookup behaviour |
5880 | * |
5881 | * The caller must hold a reference on @mm. |
5882 | * |
5883 | * Return: number of bytes copied from source to destination. |
5884 | */ |
5885 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
5886 | void *buf, int len, unsigned int gup_flags) |
5887 | { |
5888 | return __access_remote_vm(mm, addr, buf, len, gup_flags); |
5889 | } |
5890 | |
5891 | /* |
5892 | * Access another process' address space. |
5893 | * Source/target buffer must be kernel space, |
5894 | * Do not walk the page table directly, use get_user_pages |
5895 | */ |
5896 | int access_process_vm(struct task_struct *tsk, unsigned long addr, |
5897 | void *buf, int len, unsigned int gup_flags) |
5898 | { |
5899 | struct mm_struct *mm; |
5900 | int ret; |
5901 | |
5902 | mm = get_task_mm(task: tsk); |
5903 | if (!mm) |
5904 | return 0; |
5905 | |
5906 | ret = __access_remote_vm(mm, addr, buf, len, gup_flags); |
5907 | |
5908 | mmput(mm); |
5909 | |
5910 | return ret; |
5911 | } |
5912 | EXPORT_SYMBOL_GPL(access_process_vm); |
5913 | |
5914 | /* |
5915 | * Print the name of a VMA. |
5916 | */ |
5917 | void print_vma_addr(char *prefix, unsigned long ip) |
5918 | { |
5919 | struct mm_struct *mm = current->mm; |
5920 | struct vm_area_struct *vma; |
5921 | |
5922 | /* |
5923 | * we might be running from an atomic context so we cannot sleep |
5924 | */ |
5925 | if (!mmap_read_trylock(mm)) |
5926 | return; |
5927 | |
5928 | vma = find_vma(mm, addr: ip); |
5929 | if (vma && vma->vm_file) { |
5930 | struct file *f = vma->vm_file; |
5931 | char *buf = (char *)__get_free_page(GFP_NOWAIT); |
5932 | if (buf) { |
5933 | char *p; |
5934 | |
5935 | p = file_path(f, buf, PAGE_SIZE); |
5936 | if (IS_ERR(ptr: p)) |
5937 | p = "?" ; |
5938 | printk("%s%s[%lx+%lx]" , prefix, kbasename(p), |
5939 | vma->vm_start, |
5940 | vma->vm_end - vma->vm_start); |
5941 | free_page((unsigned long)buf); |
5942 | } |
5943 | } |
5944 | mmap_read_unlock(mm); |
5945 | } |
5946 | |
5947 | #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
5948 | void __might_fault(const char *file, int line) |
5949 | { |
5950 | if (pagefault_disabled()) |
5951 | return; |
5952 | __might_sleep(file, line); |
5953 | #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
5954 | if (current->mm) |
5955 | might_lock_read(¤t->mm->mmap_lock); |
5956 | #endif |
5957 | } |
5958 | EXPORT_SYMBOL(__might_fault); |
5959 | #endif |
5960 | |
5961 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) |
5962 | /* |
5963 | * Process all subpages of the specified huge page with the specified |
5964 | * operation. The target subpage will be processed last to keep its |
5965 | * cache lines hot. |
5966 | */ |
5967 | static inline int process_huge_page( |
5968 | unsigned long addr_hint, unsigned int pages_per_huge_page, |
5969 | int (*process_subpage)(unsigned long addr, int idx, void *arg), |
5970 | void *arg) |
5971 | { |
5972 | int i, n, base, l, ret; |
5973 | unsigned long addr = addr_hint & |
5974 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
5975 | |
5976 | /* Process target subpage last to keep its cache lines hot */ |
5977 | might_sleep(); |
5978 | n = (addr_hint - addr) / PAGE_SIZE; |
5979 | if (2 * n <= pages_per_huge_page) { |
5980 | /* If target subpage in first half of huge page */ |
5981 | base = 0; |
5982 | l = n; |
5983 | /* Process subpages at the end of huge page */ |
5984 | for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { |
5985 | cond_resched(); |
5986 | ret = process_subpage(addr + i * PAGE_SIZE, i, arg); |
5987 | if (ret) |
5988 | return ret; |
5989 | } |
5990 | } else { |
5991 | /* If target subpage in second half of huge page */ |
5992 | base = pages_per_huge_page - 2 * (pages_per_huge_page - n); |
5993 | l = pages_per_huge_page - n; |
5994 | /* Process subpages at the begin of huge page */ |
5995 | for (i = 0; i < base; i++) { |
5996 | cond_resched(); |
5997 | ret = process_subpage(addr + i * PAGE_SIZE, i, arg); |
5998 | if (ret) |
5999 | return ret; |
6000 | } |
6001 | } |
6002 | /* |
6003 | * Process remaining subpages in left-right-left-right pattern |
6004 | * towards the target subpage |
6005 | */ |
6006 | for (i = 0; i < l; i++) { |
6007 | int left_idx = base + i; |
6008 | int right_idx = base + 2 * l - 1 - i; |
6009 | |
6010 | cond_resched(); |
6011 | ret = process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg); |
6012 | if (ret) |
6013 | return ret; |
6014 | cond_resched(); |
6015 | ret = process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg); |
6016 | if (ret) |
6017 | return ret; |
6018 | } |
6019 | return 0; |
6020 | } |
6021 | |
6022 | static void clear_gigantic_page(struct page *page, |
6023 | unsigned long addr, |
6024 | unsigned int pages_per_huge_page) |
6025 | { |
6026 | int i; |
6027 | struct page *p; |
6028 | |
6029 | might_sleep(); |
6030 | for (i = 0; i < pages_per_huge_page; i++) { |
6031 | p = nth_page(page, i); |
6032 | cond_resched(); |
6033 | clear_user_highpage(page: p, vaddr: addr + i * PAGE_SIZE); |
6034 | } |
6035 | } |
6036 | |
6037 | static int clear_subpage(unsigned long addr, int idx, void *arg) |
6038 | { |
6039 | struct page *page = arg; |
6040 | |
6041 | clear_user_highpage(page: page + idx, vaddr: addr); |
6042 | return 0; |
6043 | } |
6044 | |
6045 | void clear_huge_page(struct page *page, |
6046 | unsigned long addr_hint, unsigned int pages_per_huge_page) |
6047 | { |
6048 | unsigned long addr = addr_hint & |
6049 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
6050 | |
6051 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
6052 | clear_gigantic_page(page, addr, pages_per_huge_page); |
6053 | return; |
6054 | } |
6055 | |
6056 | process_huge_page(addr_hint, pages_per_huge_page, process_subpage: clear_subpage, arg: page); |
6057 | } |
6058 | |
6059 | static int copy_user_gigantic_page(struct folio *dst, struct folio *src, |
6060 | unsigned long addr, |
6061 | struct vm_area_struct *vma, |
6062 | unsigned int pages_per_huge_page) |
6063 | { |
6064 | int i; |
6065 | struct page *dst_page; |
6066 | struct page *src_page; |
6067 | |
6068 | for (i = 0; i < pages_per_huge_page; i++) { |
6069 | dst_page = folio_page(dst, i); |
6070 | src_page = folio_page(src, i); |
6071 | |
6072 | cond_resched(); |
6073 | if (copy_mc_user_highpage(to: dst_page, from: src_page, |
6074 | vaddr: addr + i*PAGE_SIZE, vma)) { |
6075 | memory_failure_queue(page_to_pfn(src_page), flags: 0); |
6076 | return -EHWPOISON; |
6077 | } |
6078 | } |
6079 | return 0; |
6080 | } |
6081 | |
6082 | struct copy_subpage_arg { |
6083 | struct page *dst; |
6084 | struct page *src; |
6085 | struct vm_area_struct *vma; |
6086 | }; |
6087 | |
6088 | static int copy_subpage(unsigned long addr, int idx, void *arg) |
6089 | { |
6090 | struct copy_subpage_arg *copy_arg = arg; |
6091 | |
6092 | if (copy_mc_user_highpage(to: copy_arg->dst + idx, from: copy_arg->src + idx, |
6093 | vaddr: addr, vma: copy_arg->vma)) { |
6094 | memory_failure_queue(page_to_pfn(copy_arg->src + idx), flags: 0); |
6095 | return -EHWPOISON; |
6096 | } |
6097 | return 0; |
6098 | } |
6099 | |
6100 | int copy_user_large_folio(struct folio *dst, struct folio *src, |
6101 | unsigned long addr_hint, struct vm_area_struct *vma) |
6102 | { |
6103 | unsigned int pages_per_huge_page = folio_nr_pages(folio: dst); |
6104 | unsigned long addr = addr_hint & |
6105 | ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
6106 | struct copy_subpage_arg arg = { |
6107 | .dst = &dst->page, |
6108 | .src = &src->page, |
6109 | .vma = vma, |
6110 | }; |
6111 | |
6112 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) |
6113 | return copy_user_gigantic_page(dst, src, addr, vma, |
6114 | pages_per_huge_page); |
6115 | |
6116 | return process_huge_page(addr_hint, pages_per_huge_page, process_subpage: copy_subpage, arg: &arg); |
6117 | } |
6118 | |
6119 | long copy_folio_from_user(struct folio *dst_folio, |
6120 | const void __user *usr_src, |
6121 | bool allow_pagefault) |
6122 | { |
6123 | void *kaddr; |
6124 | unsigned long i, rc = 0; |
6125 | unsigned int nr_pages = folio_nr_pages(folio: dst_folio); |
6126 | unsigned long ret_val = nr_pages * PAGE_SIZE; |
6127 | struct page *subpage; |
6128 | |
6129 | for (i = 0; i < nr_pages; i++) { |
6130 | subpage = folio_page(dst_folio, i); |
6131 | kaddr = kmap_local_page(page: subpage); |
6132 | if (!allow_pagefault) |
6133 | pagefault_disable(); |
6134 | rc = copy_from_user(to: kaddr, from: usr_src + i * PAGE_SIZE, PAGE_SIZE); |
6135 | if (!allow_pagefault) |
6136 | pagefault_enable(); |
6137 | kunmap_local(kaddr); |
6138 | |
6139 | ret_val -= (PAGE_SIZE - rc); |
6140 | if (rc) |
6141 | break; |
6142 | |
6143 | flush_dcache_page(page: subpage); |
6144 | |
6145 | cond_resched(); |
6146 | } |
6147 | return ret_val; |
6148 | } |
6149 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ |
6150 | |
6151 | #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS |
6152 | |
6153 | static struct kmem_cache *page_ptl_cachep; |
6154 | |
6155 | void __init ptlock_cache_init(void) |
6156 | { |
6157 | page_ptl_cachep = kmem_cache_create("page->ptl" , sizeof(spinlock_t), 0, |
6158 | SLAB_PANIC, NULL); |
6159 | } |
6160 | |
6161 | bool ptlock_alloc(struct ptdesc *ptdesc) |
6162 | { |
6163 | spinlock_t *ptl; |
6164 | |
6165 | ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); |
6166 | if (!ptl) |
6167 | return false; |
6168 | ptdesc->ptl = ptl; |
6169 | return true; |
6170 | } |
6171 | |
6172 | void ptlock_free(struct ptdesc *ptdesc) |
6173 | { |
6174 | kmem_cache_free(page_ptl_cachep, ptdesc->ptl); |
6175 | } |
6176 | #endif |
6177 | |