Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * linux/mm/memory.c
4 : *
5 : * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 : */
7 :
8 : /*
9 : * demand-loading started 01.12.91 - seems it is high on the list of
10 : * things wanted, and it should be easy to implement. - Linus
11 : */
12 :
13 : /*
14 : * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 : * pages started 02.12.91, seems to work. - Linus.
16 : *
17 : * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 : * would have taken more than the 6M I have free, but it worked well as
19 : * far as I could see.
20 : *
21 : * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 : */
23 :
24 : /*
25 : * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 : * thought has to go into this. Oh, well..
27 : * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 : * Found it. Everything seems to work now.
29 : * 20.12.91 - Ok, making the swap-device changeable like the root.
30 : */
31 :
32 : /*
33 : * 05.04.94 - Multi-page memory management added for v1.1.
34 : * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 : *
36 : * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 : * (Gerhard.Wichert@pdb.siemens.de)
38 : *
39 : * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 : */
41 :
42 : #include <linux/kernel_stat.h>
43 : #include <linux/mm.h>
44 : #include <linux/mm_inline.h>
45 : #include <linux/sched/mm.h>
46 : #include <linux/sched/coredump.h>
47 : #include <linux/sched/numa_balancing.h>
48 : #include <linux/sched/task.h>
49 : #include <linux/hugetlb.h>
50 : #include <linux/mman.h>
51 : #include <linux/swap.h>
52 : #include <linux/highmem.h>
53 : #include <linux/pagemap.h>
54 : #include <linux/memremap.h>
55 : #include <linux/ksm.h>
56 : #include <linux/rmap.h>
57 : #include <linux/export.h>
58 : #include <linux/delayacct.h>
59 : #include <linux/init.h>
60 : #include <linux/pfn_t.h>
61 : #include <linux/writeback.h>
62 : #include <linux/memcontrol.h>
63 : #include <linux/mmu_notifier.h>
64 : #include <linux/swapops.h>
65 : #include <linux/elf.h>
66 : #include <linux/gfp.h>
67 : #include <linux/migrate.h>
68 : #include <linux/string.h>
69 : #include <linux/debugfs.h>
70 : #include <linux/userfaultfd_k.h>
71 : #include <linux/dax.h>
72 : #include <linux/oom.h>
73 : #include <linux/numa.h>
74 : #include <linux/perf_event.h>
75 : #include <linux/ptrace.h>
76 : #include <linux/vmalloc.h>
77 :
78 : #include <trace/events/kmem.h>
79 :
80 : #include <asm/io.h>
81 : #include <asm/mmu_context.h>
82 : #include <asm/pgalloc.h>
83 : #include <linux/uaccess.h>
84 : #include <asm/tlb.h>
85 : #include <asm/tlbflush.h>
86 :
87 : #include "pgalloc-track.h"
88 : #include "internal.h"
89 :
90 : #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
91 : #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
92 : #endif
93 :
94 : #ifndef CONFIG_NUMA
95 : unsigned long max_mapnr;
96 : EXPORT_SYMBOL(max_mapnr);
97 :
98 : struct page *mem_map;
99 : EXPORT_SYMBOL(mem_map);
100 : #endif
101 :
102 : /*
103 : * A number of key systems in x86 including ioremap() rely on the assumption
104 : * that high_memory defines the upper bound on direct map memory, then end
105 : * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
106 : * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
107 : * and ZONE_HIGHMEM.
108 : */
109 : void *high_memory;
110 : EXPORT_SYMBOL(high_memory);
111 :
112 : /*
113 : * Randomize the address space (stacks, mmaps, brk, etc.).
114 : *
115 : * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
116 : * as ancient (libc5 based) binaries can segfault. )
117 : */
118 : int randomize_va_space __read_mostly =
119 : #ifdef CONFIG_COMPAT_BRK
120 : 1;
121 : #else
122 : 2;
123 : #endif
124 :
125 : #ifndef arch_faults_on_old_pte
126 : static inline bool arch_faults_on_old_pte(void)
127 : {
128 : /*
129 : * Those arches which don't have hw access flag feature need to
130 : * implement their own helper. By default, "true" means pagefault
131 : * will be hit on old pte.
132 : */
133 : return true;
134 : }
135 : #endif
136 :
137 : #ifndef arch_wants_old_prefaulted_pte
138 : static inline bool arch_wants_old_prefaulted_pte(void)
139 : {
140 : /*
141 : * Transitioning a PTE from 'old' to 'young' can be expensive on
142 : * some architectures, even if it's performed in hardware. By
143 : * default, "false" means prefaulted entries will be 'young'.
144 : */
145 : return false;
146 : }
147 : #endif
148 :
149 0 : static int __init disable_randmaps(char *s)
150 : {
151 0 : randomize_va_space = 0;
152 0 : return 1;
153 : }
154 : __setup("norandmaps", disable_randmaps);
155 :
156 : unsigned long zero_pfn __read_mostly;
157 : EXPORT_SYMBOL(zero_pfn);
158 :
159 : unsigned long highest_memmap_pfn __read_mostly;
160 :
161 : /*
162 : * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
163 : */
164 1 : static int __init init_zero_pfn(void)
165 : {
166 2 : zero_pfn = page_to_pfn(ZERO_PAGE(0));
167 1 : return 0;
168 : }
169 : early_initcall(init_zero_pfn);
170 :
171 0 : void mm_trace_rss_stat(struct mm_struct *mm, int member, long count)
172 : {
173 0 : trace_rss_stat(mm, member, count);
174 0 : }
175 :
176 : #if defined(SPLIT_RSS_COUNTING)
177 :
178 : void sync_mm_rss(struct mm_struct *mm)
179 : {
180 : int i;
181 :
182 : for (i = 0; i < NR_MM_COUNTERS; i++) {
183 : if (current->rss_stat.count[i]) {
184 : add_mm_counter(mm, i, current->rss_stat.count[i]);
185 : current->rss_stat.count[i] = 0;
186 : }
187 : }
188 : current->rss_stat.events = 0;
189 : }
190 :
191 : static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
192 : {
193 : struct task_struct *task = current;
194 :
195 : if (likely(task->mm == mm))
196 : task->rss_stat.count[member] += val;
197 : else
198 : add_mm_counter(mm, member, val);
199 : }
200 : #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
201 : #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
202 :
203 : /* sync counter once per 64 page faults */
204 : #define TASK_RSS_EVENTS_THRESH (64)
205 : static void check_sync_rss_stat(struct task_struct *task)
206 : {
207 : if (unlikely(task != current))
208 : return;
209 : if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
210 : sync_mm_rss(task->mm);
211 : }
212 : #else /* SPLIT_RSS_COUNTING */
213 :
214 : #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
215 : #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
216 :
217 : static void check_sync_rss_stat(struct task_struct *task)
218 : {
219 : }
220 :
221 : #endif /* SPLIT_RSS_COUNTING */
222 :
223 : /*
224 : * Note: this doesn't free the actual pages themselves. That
225 : * has been handled earlier when unmapping all the memory regions.
226 : */
227 0 : static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
228 : unsigned long addr)
229 : {
230 0 : pgtable_t token = pmd_pgtable(*pmd);
231 0 : pmd_clear(pmd);
232 0 : pte_free_tlb(tlb, token, addr);
233 0 : mm_dec_nr_ptes(tlb->mm);
234 0 : }
235 :
236 0 : static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
237 : unsigned long addr, unsigned long end,
238 : unsigned long floor, unsigned long ceiling)
239 : {
240 : pmd_t *pmd;
241 : unsigned long next;
242 : unsigned long start;
243 :
244 0 : start = addr;
245 0 : pmd = pmd_offset(pud, addr);
246 : do {
247 0 : next = pmd_addr_end(addr, end);
248 0 : if (pmd_none_or_clear_bad(pmd))
249 0 : continue;
250 0 : free_pte_range(tlb, pmd, addr);
251 0 : } while (pmd++, addr = next, addr != end);
252 :
253 0 : start &= PUD_MASK;
254 0 : if (start < floor)
255 : return;
256 0 : if (ceiling) {
257 0 : ceiling &= PUD_MASK;
258 0 : if (!ceiling)
259 : return;
260 : }
261 0 : if (end - 1 > ceiling - 1)
262 : return;
263 :
264 0 : pmd = pmd_offset(pud, start);
265 0 : pud_clear(pud);
266 0 : pmd_free_tlb(tlb, pmd, start);
267 0 : mm_dec_nr_pmds(tlb->mm);
268 : }
269 :
270 0 : static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
271 : unsigned long addr, unsigned long end,
272 : unsigned long floor, unsigned long ceiling)
273 : {
274 : pud_t *pud;
275 : unsigned long next;
276 : unsigned long start;
277 :
278 0 : start = addr;
279 0 : pud = pud_offset(p4d, addr);
280 : do {
281 0 : next = pud_addr_end(addr, end);
282 0 : if (pud_none_or_clear_bad(pud))
283 0 : continue;
284 0 : free_pmd_range(tlb, pud, addr, next, floor, ceiling);
285 0 : } while (pud++, addr = next, addr != end);
286 :
287 0 : start &= P4D_MASK;
288 : if (start < floor)
289 : return;
290 : if (ceiling) {
291 : ceiling &= P4D_MASK;
292 : if (!ceiling)
293 : return;
294 : }
295 : if (end - 1 > ceiling - 1)
296 : return;
297 :
298 : pud = pud_offset(p4d, start);
299 : p4d_clear(p4d);
300 : pud_free_tlb(tlb, pud, start);
301 : mm_dec_nr_puds(tlb->mm);
302 : }
303 :
304 : static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
305 : unsigned long addr, unsigned long end,
306 : unsigned long floor, unsigned long ceiling)
307 : {
308 : p4d_t *p4d;
309 : unsigned long next;
310 : unsigned long start;
311 :
312 0 : start = addr;
313 0 : p4d = p4d_offset(pgd, addr);
314 : do {
315 0 : next = p4d_addr_end(addr, end);
316 0 : if (p4d_none_or_clear_bad(p4d))
317 : continue;
318 0 : free_pud_range(tlb, p4d, addr, next, floor, ceiling);
319 0 : } while (p4d++, addr = next, addr != end);
320 :
321 0 : start &= PGDIR_MASK;
322 : if (start < floor)
323 : return;
324 : if (ceiling) {
325 : ceiling &= PGDIR_MASK;
326 : if (!ceiling)
327 : return;
328 : }
329 : if (end - 1 > ceiling - 1)
330 : return;
331 :
332 : p4d = p4d_offset(pgd, start);
333 : pgd_clear(pgd);
334 : p4d_free_tlb(tlb, p4d, start);
335 : }
336 :
337 : /*
338 : * This function frees user-level page tables of a process.
339 : */
340 0 : void free_pgd_range(struct mmu_gather *tlb,
341 : unsigned long addr, unsigned long end,
342 : unsigned long floor, unsigned long ceiling)
343 : {
344 : pgd_t *pgd;
345 : unsigned long next;
346 :
347 : /*
348 : * The next few lines have given us lots of grief...
349 : *
350 : * Why are we testing PMD* at this top level? Because often
351 : * there will be no work to do at all, and we'd prefer not to
352 : * go all the way down to the bottom just to discover that.
353 : *
354 : * Why all these "- 1"s? Because 0 represents both the bottom
355 : * of the address space and the top of it (using -1 for the
356 : * top wouldn't help much: the masks would do the wrong thing).
357 : * The rule is that addr 0 and floor 0 refer to the bottom of
358 : * the address space, but end 0 and ceiling 0 refer to the top
359 : * Comparisons need to use "end - 1" and "ceiling - 1" (though
360 : * that end 0 case should be mythical).
361 : *
362 : * Wherever addr is brought up or ceiling brought down, we must
363 : * be careful to reject "the opposite 0" before it confuses the
364 : * subsequent tests. But what about where end is brought down
365 : * by PMD_SIZE below? no, end can't go down to 0 there.
366 : *
367 : * Whereas we round start (addr) and ceiling down, by different
368 : * masks at different levels, in order to test whether a table
369 : * now has no other vmas using it, so can be freed, we don't
370 : * bother to round floor or end up - the tests don't need that.
371 : */
372 :
373 0 : addr &= PMD_MASK;
374 0 : if (addr < floor) {
375 0 : addr += PMD_SIZE;
376 0 : if (!addr)
377 : return;
378 : }
379 0 : if (ceiling) {
380 0 : ceiling &= PMD_MASK;
381 0 : if (!ceiling)
382 : return;
383 : }
384 0 : if (end - 1 > ceiling - 1)
385 0 : end -= PMD_SIZE;
386 0 : if (addr > end - 1)
387 : return;
388 : /*
389 : * We add page table cache pages with PAGE_SIZE,
390 : * (see pte_free_tlb()), flush the tlb if we need
391 : */
392 0 : tlb_change_page_size(tlb, PAGE_SIZE);
393 0 : pgd = pgd_offset(tlb->mm, addr);
394 : do {
395 0 : next = pgd_addr_end(addr, end);
396 0 : if (pgd_none_or_clear_bad(pgd))
397 : continue;
398 : free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
399 0 : } while (pgd++, addr = next, addr != end);
400 : }
401 :
402 0 : void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
403 : unsigned long floor, unsigned long ceiling)
404 : {
405 0 : while (vma) {
406 0 : struct vm_area_struct *next = vma->vm_next;
407 0 : unsigned long addr = vma->vm_start;
408 :
409 : /*
410 : * Hide vma from rmap and truncate_pagecache before freeing
411 : * pgtables
412 : */
413 0 : unlink_anon_vmas(vma);
414 0 : unlink_file_vma(vma);
415 :
416 0 : if (is_vm_hugetlb_page(vma)) {
417 : hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
418 : floor, next ? next->vm_start : ceiling);
419 : } else {
420 : /*
421 : * Optimization: gather nearby vmas into one call down
422 : */
423 0 : while (next && next->vm_start <= vma->vm_end + PMD_SIZE
424 0 : && !is_vm_hugetlb_page(next)) {
425 0 : vma = next;
426 0 : next = vma->vm_next;
427 0 : unlink_anon_vmas(vma);
428 0 : unlink_file_vma(vma);
429 : }
430 0 : free_pgd_range(tlb, addr, vma->vm_end,
431 : floor, next ? next->vm_start : ceiling);
432 : }
433 0 : vma = next;
434 : }
435 0 : }
436 :
437 0 : void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
438 : {
439 0 : spinlock_t *ptl = pmd_lock(mm, pmd);
440 :
441 0 : if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
442 0 : mm_inc_nr_ptes(mm);
443 : /*
444 : * Ensure all pte setup (eg. pte page lock and page clearing) are
445 : * visible before the pte is made visible to other CPUs by being
446 : * put into page tables.
447 : *
448 : * The other side of the story is the pointer chasing in the page
449 : * table walking code (when walking the page table without locking;
450 : * ie. most of the time). Fortunately, these data accesses consist
451 : * of a chain of data-dependent loads, meaning most CPUs (alpha
452 : * being the notable exception) will already guarantee loads are
453 : * seen in-order. See the alpha page table accessors for the
454 : * smp_rmb() barriers in page table walking code.
455 : */
456 0 : smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
457 0 : pmd_populate(mm, pmd, *pte);
458 0 : *pte = NULL;
459 : }
460 0 : spin_unlock(ptl);
461 0 : }
462 :
463 0 : int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
464 : {
465 0 : pgtable_t new = pte_alloc_one(mm);
466 0 : if (!new)
467 : return -ENOMEM;
468 :
469 0 : pmd_install(mm, pmd, &new);
470 0 : if (new)
471 0 : pte_free(mm, new);
472 : return 0;
473 : }
474 :
475 1 : int __pte_alloc_kernel(pmd_t *pmd)
476 : {
477 2 : pte_t *new = pte_alloc_one_kernel(&init_mm);
478 1 : if (!new)
479 : return -ENOMEM;
480 :
481 1 : spin_lock(&init_mm.page_table_lock);
482 1 : if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
483 1 : smp_wmb(); /* See comment in pmd_install() */
484 2 : pmd_populate_kernel(&init_mm, pmd, new);
485 1 : new = NULL;
486 : }
487 1 : spin_unlock(&init_mm.page_table_lock);
488 1 : if (new)
489 0 : pte_free_kernel(&init_mm, new);
490 : return 0;
491 : }
492 :
493 : static inline void init_rss_vec(int *rss)
494 : {
495 0 : memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
496 : }
497 :
498 : static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
499 : {
500 : int i;
501 :
502 0 : if (current->mm == mm)
503 : sync_mm_rss(mm);
504 0 : for (i = 0; i < NR_MM_COUNTERS; i++)
505 0 : if (rss[i])
506 0 : add_mm_counter(mm, i, rss[i]);
507 : }
508 :
509 : /*
510 : * This function is called to print an error when a bad pte
511 : * is found. For example, we might have a PFN-mapped pte in
512 : * a region that doesn't allow it.
513 : *
514 : * The calling function must still handle the error.
515 : */
516 0 : static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
517 : pte_t pte, struct page *page)
518 : {
519 0 : pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
520 0 : p4d_t *p4d = p4d_offset(pgd, addr);
521 0 : pud_t *pud = pud_offset(p4d, addr);
522 0 : pmd_t *pmd = pmd_offset(pud, addr);
523 : struct address_space *mapping;
524 : pgoff_t index;
525 : static unsigned long resume;
526 : static unsigned long nr_shown;
527 : static unsigned long nr_unshown;
528 :
529 : /*
530 : * Allow a burst of 60 reports, then keep quiet for that minute;
531 : * or allow a steady drip of one report per second.
532 : */
533 0 : if (nr_shown == 60) {
534 0 : if (time_before(jiffies, resume)) {
535 0 : nr_unshown++;
536 0 : return;
537 : }
538 0 : if (nr_unshown) {
539 0 : pr_alert("BUG: Bad page map: %lu messages suppressed\n",
540 : nr_unshown);
541 0 : nr_unshown = 0;
542 : }
543 0 : nr_shown = 0;
544 : }
545 0 : if (nr_shown++ == 0)
546 0 : resume = jiffies + 60 * HZ;
547 :
548 0 : mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
549 0 : index = linear_page_index(vma, addr);
550 :
551 0 : pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
552 : current->comm,
553 : (long long)pte_val(pte), (long long)pmd_val(*pmd));
554 0 : if (page)
555 0 : dump_page(page, "bad pte");
556 0 : pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
557 : (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
558 0 : pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
559 : vma->vm_file,
560 : vma->vm_ops ? vma->vm_ops->fault : NULL,
561 : vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
562 : mapping ? mapping->a_ops->readpage : NULL);
563 0 : dump_stack();
564 0 : add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
565 : }
566 :
567 : /*
568 : * vm_normal_page -- This function gets the "struct page" associated with a pte.
569 : *
570 : * "Special" mappings do not wish to be associated with a "struct page" (either
571 : * it doesn't exist, or it exists but they don't want to touch it). In this
572 : * case, NULL is returned here. "Normal" mappings do have a struct page.
573 : *
574 : * There are 2 broad cases. Firstly, an architecture may define a pte_special()
575 : * pte bit, in which case this function is trivial. Secondly, an architecture
576 : * may not have a spare pte bit, which requires a more complicated scheme,
577 : * described below.
578 : *
579 : * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
580 : * special mapping (even if there are underlying and valid "struct pages").
581 : * COWed pages of a VM_PFNMAP are always normal.
582 : *
583 : * The way we recognize COWed pages within VM_PFNMAP mappings is through the
584 : * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
585 : * set, and the vm_pgoff will point to the first PFN mapped: thus every special
586 : * mapping will always honor the rule
587 : *
588 : * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
589 : *
590 : * And for normal mappings this is false.
591 : *
592 : * This restricts such mappings to be a linear translation from virtual address
593 : * to pfn. To get around this restriction, we allow arbitrary mappings so long
594 : * as the vma is not a COW mapping; in that case, we know that all ptes are
595 : * special (because none can have been COWed).
596 : *
597 : *
598 : * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
599 : *
600 : * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
601 : * page" backing, however the difference is that _all_ pages with a struct
602 : * page (that is, those where pfn_valid is true) are refcounted and considered
603 : * normal pages by the VM. The disadvantage is that pages are refcounted
604 : * (which can be slower and simply not an option for some PFNMAP users). The
605 : * advantage is that we don't have to follow the strict linearity rule of
606 : * PFNMAP mappings in order to support COWable mappings.
607 : *
608 : */
609 0 : struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
610 : pte_t pte)
611 : {
612 0 : unsigned long pfn = pte_pfn(pte);
613 :
614 : if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
615 : if (likely(!pte_special(pte)))
616 : goto check_pfn;
617 : if (vma->vm_ops && vma->vm_ops->find_special_page)
618 : return vma->vm_ops->find_special_page(vma, addr);
619 : if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
620 : return NULL;
621 : if (is_zero_pfn(pfn))
622 : return NULL;
623 : if (pte_devmap(pte))
624 : return NULL;
625 :
626 : print_bad_pte(vma, addr, pte, NULL);
627 : return NULL;
628 : }
629 :
630 : /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
631 :
632 0 : if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
633 0 : if (vma->vm_flags & VM_MIXEDMAP) {
634 0 : if (!pfn_valid(pfn))
635 : return NULL;
636 : goto out;
637 : } else {
638 : unsigned long off;
639 0 : off = (addr - vma->vm_start) >> PAGE_SHIFT;
640 0 : if (pfn == vma->vm_pgoff + off)
641 : return NULL;
642 0 : if (!is_cow_mapping(vma->vm_flags))
643 : return NULL;
644 : }
645 : }
646 :
647 0 : if (is_zero_pfn(pfn))
648 : return NULL;
649 :
650 : check_pfn:
651 0 : if (unlikely(pfn > highest_memmap_pfn)) {
652 0 : print_bad_pte(vma, addr, pte, NULL);
653 0 : return NULL;
654 : }
655 :
656 : /*
657 : * NOTE! We still have PageReserved() pages in the page tables.
658 : * eg. VDSO mappings can cause them to exist.
659 : */
660 : out:
661 0 : return pfn_to_page(pfn);
662 : }
663 :
664 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
665 : struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
666 : pmd_t pmd)
667 : {
668 : unsigned long pfn = pmd_pfn(pmd);
669 :
670 : /*
671 : * There is no pmd_special() but there may be special pmds, e.g.
672 : * in a direct-access (dax) mapping, so let's just replicate the
673 : * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
674 : */
675 : if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
676 : if (vma->vm_flags & VM_MIXEDMAP) {
677 : if (!pfn_valid(pfn))
678 : return NULL;
679 : goto out;
680 : } else {
681 : unsigned long off;
682 : off = (addr - vma->vm_start) >> PAGE_SHIFT;
683 : if (pfn == vma->vm_pgoff + off)
684 : return NULL;
685 : if (!is_cow_mapping(vma->vm_flags))
686 : return NULL;
687 : }
688 : }
689 :
690 : if (pmd_devmap(pmd))
691 : return NULL;
692 : if (is_huge_zero_pmd(pmd))
693 : return NULL;
694 : if (unlikely(pfn > highest_memmap_pfn))
695 : return NULL;
696 :
697 : /*
698 : * NOTE! We still have PageReserved() pages in the page tables.
699 : * eg. VDSO mappings can cause them to exist.
700 : */
701 : out:
702 : return pfn_to_page(pfn);
703 : }
704 : #endif
705 :
706 : static void restore_exclusive_pte(struct vm_area_struct *vma,
707 : struct page *page, unsigned long address,
708 : pte_t *ptep)
709 : {
710 : pte_t pte;
711 : swp_entry_t entry;
712 :
713 : pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
714 : if (pte_swp_soft_dirty(*ptep))
715 : pte = pte_mksoft_dirty(pte);
716 :
717 : entry = pte_to_swp_entry(*ptep);
718 : if (pte_swp_uffd_wp(*ptep))
719 : pte = pte_mkuffd_wp(pte);
720 : else if (is_writable_device_exclusive_entry(entry))
721 : pte = maybe_mkwrite(pte_mkdirty(pte), vma);
722 :
723 : /*
724 : * No need to take a page reference as one was already
725 : * created when the swap entry was made.
726 : */
727 : if (PageAnon(page))
728 : page_add_anon_rmap(page, vma, address, false);
729 : else
730 : /*
731 : * Currently device exclusive access only supports anonymous
732 : * memory so the entry shouldn't point to a filebacked page.
733 : */
734 : WARN_ON_ONCE(!PageAnon(page));
735 :
736 : set_pte_at(vma->vm_mm, address, ptep, pte);
737 :
738 : /*
739 : * No need to invalidate - it was non-present before. However
740 : * secondary CPUs may have mappings that need invalidating.
741 : */
742 : update_mmu_cache(vma, address, ptep);
743 : }
744 :
745 : /*
746 : * Tries to restore an exclusive pte if the page lock can be acquired without
747 : * sleeping.
748 : */
749 : static int
750 : try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
751 : unsigned long addr)
752 : {
753 : swp_entry_t entry = pte_to_swp_entry(*src_pte);
754 : struct page *page = pfn_swap_entry_to_page(entry);
755 :
756 : if (trylock_page(page)) {
757 : restore_exclusive_pte(vma, page, addr, src_pte);
758 : unlock_page(page);
759 : return 0;
760 : }
761 :
762 : return -EBUSY;
763 : }
764 :
765 : /*
766 : * copy one vm_area from one task to the other. Assumes the page tables
767 : * already present in the new task to be cleared in the whole range
768 : * covered by this vma.
769 : */
770 :
771 : static unsigned long
772 0 : copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
773 : pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
774 : struct vm_area_struct *src_vma, unsigned long addr, int *rss)
775 : {
776 0 : unsigned long vm_flags = dst_vma->vm_flags;
777 0 : pte_t pte = *src_pte;
778 : struct page *page;
779 0 : swp_entry_t entry = pte_to_swp_entry(pte);
780 :
781 0 : if (likely(!non_swap_entry(entry))) {
782 0 : if (swap_duplicate(entry) < 0)
783 : return -EIO;
784 :
785 : /* make sure dst_mm is on swapoff's mmlist. */
786 0 : if (unlikely(list_empty(&dst_mm->mmlist))) {
787 0 : spin_lock(&mmlist_lock);
788 0 : if (list_empty(&dst_mm->mmlist))
789 0 : list_add(&dst_mm->mmlist,
790 : &src_mm->mmlist);
791 : spin_unlock(&mmlist_lock);
792 : }
793 0 : rss[MM_SWAPENTS]++;
794 0 : } else if (is_migration_entry(entry)) {
795 0 : page = pfn_swap_entry_to_page(entry);
796 :
797 0 : rss[mm_counter(page)]++;
798 :
799 0 : if (is_writable_migration_entry(entry) &&
800 0 : is_cow_mapping(vm_flags)) {
801 : /*
802 : * COW mappings require pages in both
803 : * parent and child to be set to read.
804 : */
805 0 : entry = make_readable_migration_entry(
806 : swp_offset(entry));
807 0 : pte = swp_entry_to_pte(entry);
808 0 : if (pte_swp_soft_dirty(*src_pte))
809 : pte = pte_swp_mksoft_dirty(pte);
810 : if (pte_swp_uffd_wp(*src_pte))
811 : pte = pte_swp_mkuffd_wp(pte);
812 0 : set_pte_at(src_mm, addr, src_pte, pte);
813 : }
814 : } else if (is_device_private_entry(entry)) {
815 : page = pfn_swap_entry_to_page(entry);
816 :
817 : /*
818 : * Update rss count even for unaddressable pages, as
819 : * they should treated just like normal pages in this
820 : * respect.
821 : *
822 : * We will likely want to have some new rss counters
823 : * for unaddressable pages, at some point. But for now
824 : * keep things as they are.
825 : */
826 : get_page(page);
827 : rss[mm_counter(page)]++;
828 : page_dup_rmap(page, false);
829 :
830 : /*
831 : * We do not preserve soft-dirty information, because so
832 : * far, checkpoint/restore is the only feature that
833 : * requires that. And checkpoint/restore does not work
834 : * when a device driver is involved (you cannot easily
835 : * save and restore device driver state).
836 : */
837 : if (is_writable_device_private_entry(entry) &&
838 : is_cow_mapping(vm_flags)) {
839 : entry = make_readable_device_private_entry(
840 : swp_offset(entry));
841 : pte = swp_entry_to_pte(entry);
842 : if (pte_swp_uffd_wp(*src_pte))
843 : pte = pte_swp_mkuffd_wp(pte);
844 : set_pte_at(src_mm, addr, src_pte, pte);
845 : }
846 : } else if (is_device_exclusive_entry(entry)) {
847 : /*
848 : * Make device exclusive entries present by restoring the
849 : * original entry then copying as for a present pte. Device
850 : * exclusive entries currently only support private writable
851 : * (ie. COW) mappings.
852 : */
853 : VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
854 : if (try_restore_exclusive_pte(src_pte, src_vma, addr))
855 : return -EBUSY;
856 : return -ENOENT;
857 : }
858 0 : if (!userfaultfd_wp(dst_vma))
859 : pte = pte_swp_clear_uffd_wp(pte);
860 0 : set_pte_at(dst_mm, addr, dst_pte, pte);
861 : return 0;
862 : }
863 :
864 : /*
865 : * Copy a present and normal page if necessary.
866 : *
867 : * NOTE! The usual case is that this doesn't need to do
868 : * anything, and can just return a positive value. That
869 : * will let the caller know that it can just increase
870 : * the page refcount and re-use the pte the traditional
871 : * way.
872 : *
873 : * But _if_ we need to copy it because it needs to be
874 : * pinned in the parent (and the child should get its own
875 : * copy rather than just a reference to the same page),
876 : * we'll do that here and return zero to let the caller
877 : * know we're done.
878 : *
879 : * And if we need a pre-allocated page but don't yet have
880 : * one, return a negative error to let the preallocation
881 : * code know so that it can do so outside the page table
882 : * lock.
883 : */
884 : static inline int
885 0 : copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
886 : pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
887 : struct page **prealloc, pte_t pte, struct page *page)
888 : {
889 : struct page *new_page;
890 :
891 : /*
892 : * What we want to do is to check whether this page may
893 : * have been pinned by the parent process. If so,
894 : * instead of wrprotect the pte on both sides, we copy
895 : * the page immediately so that we'll always guarantee
896 : * the pinned page won't be randomly replaced in the
897 : * future.
898 : *
899 : * The page pinning checks are just "has this mm ever
900 : * seen pinning", along with the (inexact) check of
901 : * the page count. That might give false positives for
902 : * for pinning, but it will work correctly.
903 : */
904 0 : if (likely(!page_needs_cow_for_dma(src_vma, page)))
905 : return 1;
906 :
907 0 : new_page = *prealloc;
908 0 : if (!new_page)
909 : return -EAGAIN;
910 :
911 : /*
912 : * We have a prealloc page, all good! Take it
913 : * over and copy the page & arm it.
914 : */
915 0 : *prealloc = NULL;
916 0 : copy_user_highpage(new_page, page, addr, src_vma);
917 0 : __SetPageUptodate(new_page);
918 0 : page_add_new_anon_rmap(new_page, dst_vma, addr, false);
919 0 : lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
920 0 : rss[mm_counter(new_page)]++;
921 :
922 : /* All done, just insert the new page copy in the child */
923 0 : pte = mk_pte(new_page, dst_vma->vm_page_prot);
924 0 : pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
925 0 : if (userfaultfd_pte_wp(dst_vma, *src_pte))
926 : /* Uffd-wp needs to be delivered to dest pte as well */
927 : pte = pte_wrprotect(pte_mkuffd_wp(pte));
928 0 : set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
929 : return 0;
930 : }
931 :
932 : /*
933 : * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
934 : * is required to copy this pte.
935 : */
936 : static inline int
937 0 : copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
938 : pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
939 : struct page **prealloc)
940 : {
941 0 : struct mm_struct *src_mm = src_vma->vm_mm;
942 0 : unsigned long vm_flags = src_vma->vm_flags;
943 0 : pte_t pte = *src_pte;
944 : struct page *page;
945 :
946 0 : page = vm_normal_page(src_vma, addr, pte);
947 0 : if (page) {
948 : int retval;
949 :
950 0 : retval = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
951 : addr, rss, prealloc, pte, page);
952 0 : if (retval <= 0)
953 : return retval;
954 :
955 0 : get_page(page);
956 0 : page_dup_rmap(page, false);
957 0 : rss[mm_counter(page)]++;
958 : }
959 :
960 : /*
961 : * If it's a COW mapping, write protect it both
962 : * in the parent and the child
963 : */
964 0 : if (is_cow_mapping(vm_flags) && pte_write(pte)) {
965 0 : ptep_set_wrprotect(src_mm, addr, src_pte);
966 : pte = pte_wrprotect(pte);
967 : }
968 :
969 : /*
970 : * If it's a shared mapping, mark it clean in
971 : * the child
972 : */
973 0 : if (vm_flags & VM_SHARED)
974 : pte = pte_mkclean(pte);
975 0 : pte = pte_mkold(pte);
976 :
977 0 : if (!userfaultfd_wp(dst_vma))
978 : pte = pte_clear_uffd_wp(pte);
979 :
980 0 : set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
981 : return 0;
982 : }
983 :
984 : static inline struct page *
985 : page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
986 : unsigned long addr)
987 : {
988 : struct page *new_page;
989 :
990 0 : new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
991 0 : if (!new_page)
992 : return NULL;
993 :
994 : if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) {
995 : put_page(new_page);
996 : return NULL;
997 : }
998 : cgroup_throttle_swaprate(new_page, GFP_KERNEL);
999 :
1000 : return new_page;
1001 : }
1002 :
1003 : static int
1004 0 : copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1005 : pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1006 : unsigned long end)
1007 : {
1008 0 : struct mm_struct *dst_mm = dst_vma->vm_mm;
1009 0 : struct mm_struct *src_mm = src_vma->vm_mm;
1010 : pte_t *orig_src_pte, *orig_dst_pte;
1011 : pte_t *src_pte, *dst_pte;
1012 : spinlock_t *src_ptl, *dst_ptl;
1013 0 : int progress, ret = 0;
1014 : int rss[NR_MM_COUNTERS];
1015 0 : swp_entry_t entry = (swp_entry_t){0};
1016 0 : struct page *prealloc = NULL;
1017 :
1018 : again:
1019 0 : progress = 0;
1020 0 : init_rss_vec(rss);
1021 :
1022 0 : dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1023 0 : if (!dst_pte) {
1024 : ret = -ENOMEM;
1025 : goto out;
1026 : }
1027 0 : src_pte = pte_offset_map(src_pmd, addr);
1028 0 : src_ptl = pte_lockptr(src_mm, src_pmd);
1029 0 : spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1030 0 : orig_src_pte = src_pte;
1031 0 : orig_dst_pte = dst_pte;
1032 : arch_enter_lazy_mmu_mode();
1033 :
1034 : do {
1035 : /*
1036 : * We are holding two locks at this point - either of them
1037 : * could generate latencies in another task on another CPU.
1038 : */
1039 0 : if (progress >= 32) {
1040 0 : progress = 0;
1041 0 : if (need_resched() ||
1042 : spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1043 : break;
1044 : }
1045 0 : if (pte_none(*src_pte)) {
1046 0 : progress++;
1047 0 : continue;
1048 : }
1049 0 : if (unlikely(!pte_present(*src_pte))) {
1050 0 : ret = copy_nonpresent_pte(dst_mm, src_mm,
1051 : dst_pte, src_pte,
1052 : dst_vma, src_vma,
1053 : addr, rss);
1054 0 : if (ret == -EIO) {
1055 : entry = pte_to_swp_entry(*src_pte);
1056 : break;
1057 0 : } else if (ret == -EBUSY) {
1058 : break;
1059 0 : } else if (!ret) {
1060 0 : progress += 8;
1061 0 : continue;
1062 : }
1063 :
1064 : /*
1065 : * Device exclusive entry restored, continue by copying
1066 : * the now present pte.
1067 : */
1068 0 : WARN_ON_ONCE(ret != -ENOENT);
1069 : }
1070 : /* copy_present_pte() will clear `*prealloc' if consumed */
1071 0 : ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
1072 : addr, rss, &prealloc);
1073 : /*
1074 : * If we need a pre-allocated page for this pte, drop the
1075 : * locks, allocate, and try again.
1076 : */
1077 0 : if (unlikely(ret == -EAGAIN))
1078 : break;
1079 0 : if (unlikely(prealloc)) {
1080 : /*
1081 : * pre-alloc page cannot be reused by next time so as
1082 : * to strictly follow mempolicy (e.g., alloc_page_vma()
1083 : * will allocate page according to address). This
1084 : * could only happen if one pinned pte changed.
1085 : */
1086 0 : put_page(prealloc);
1087 0 : prealloc = NULL;
1088 : }
1089 0 : progress += 8;
1090 0 : } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1091 :
1092 : arch_leave_lazy_mmu_mode();
1093 0 : spin_unlock(src_ptl);
1094 : pte_unmap(orig_src_pte);
1095 0 : add_mm_rss_vec(dst_mm, rss);
1096 0 : pte_unmap_unlock(orig_dst_pte, dst_ptl);
1097 0 : cond_resched();
1098 :
1099 0 : if (ret == -EIO) {
1100 : VM_WARN_ON_ONCE(!entry.val);
1101 0 : if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1102 : ret = -ENOMEM;
1103 : goto out;
1104 : }
1105 0 : entry.val = 0;
1106 0 : } else if (ret == -EBUSY) {
1107 : goto out;
1108 0 : } else if (ret == -EAGAIN) {
1109 0 : prealloc = page_copy_prealloc(src_mm, src_vma, addr);
1110 0 : if (!prealloc)
1111 : return -ENOMEM;
1112 : } else if (ret) {
1113 : VM_WARN_ON_ONCE(1);
1114 : }
1115 :
1116 : /* We've captured and resolved the error. Reset, try again. */
1117 0 : ret = 0;
1118 :
1119 0 : if (addr != end)
1120 : goto again;
1121 : out:
1122 0 : if (unlikely(prealloc))
1123 0 : put_page(prealloc);
1124 : return ret;
1125 : }
1126 :
1127 : static inline int
1128 0 : copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1129 : pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1130 : unsigned long end)
1131 : {
1132 0 : struct mm_struct *dst_mm = dst_vma->vm_mm;
1133 0 : struct mm_struct *src_mm = src_vma->vm_mm;
1134 : pmd_t *src_pmd, *dst_pmd;
1135 : unsigned long next;
1136 :
1137 0 : dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1138 0 : if (!dst_pmd)
1139 : return -ENOMEM;
1140 0 : src_pmd = pmd_offset(src_pud, addr);
1141 : do {
1142 0 : next = pmd_addr_end(addr, end);
1143 0 : if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1144 0 : || pmd_devmap(*src_pmd)) {
1145 : int err;
1146 : VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1147 : err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1148 : addr, dst_vma, src_vma);
1149 : if (err == -ENOMEM)
1150 : return -ENOMEM;
1151 : if (!err)
1152 : continue;
1153 : /* fall through */
1154 : }
1155 0 : if (pmd_none_or_clear_bad(src_pmd))
1156 0 : continue;
1157 0 : if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1158 : addr, next))
1159 : return -ENOMEM;
1160 0 : } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1161 : return 0;
1162 : }
1163 :
1164 : static inline int
1165 0 : copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1166 : p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1167 : unsigned long end)
1168 : {
1169 0 : struct mm_struct *dst_mm = dst_vma->vm_mm;
1170 0 : struct mm_struct *src_mm = src_vma->vm_mm;
1171 : pud_t *src_pud, *dst_pud;
1172 : unsigned long next;
1173 :
1174 0 : dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1175 0 : if (!dst_pud)
1176 : return -ENOMEM;
1177 0 : src_pud = pud_offset(src_p4d, addr);
1178 : do {
1179 0 : next = pud_addr_end(addr, end);
1180 0 : if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1181 : int err;
1182 :
1183 : VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1184 : err = copy_huge_pud(dst_mm, src_mm,
1185 : dst_pud, src_pud, addr, src_vma);
1186 : if (err == -ENOMEM)
1187 : return -ENOMEM;
1188 : if (!err)
1189 : continue;
1190 : /* fall through */
1191 : }
1192 0 : if (pud_none_or_clear_bad(src_pud))
1193 0 : continue;
1194 0 : if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1195 : addr, next))
1196 : return -ENOMEM;
1197 0 : } while (dst_pud++, src_pud++, addr = next, addr != end);
1198 0 : return 0;
1199 : }
1200 :
1201 : static inline int
1202 : copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1203 : pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1204 : unsigned long end)
1205 : {
1206 0 : struct mm_struct *dst_mm = dst_vma->vm_mm;
1207 : p4d_t *src_p4d, *dst_p4d;
1208 : unsigned long next;
1209 :
1210 0 : dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1211 0 : if (!dst_p4d)
1212 : return -ENOMEM;
1213 0 : src_p4d = p4d_offset(src_pgd, addr);
1214 : do {
1215 0 : next = p4d_addr_end(addr, end);
1216 0 : if (p4d_none_or_clear_bad(src_p4d))
1217 : continue;
1218 0 : if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1219 : addr, next))
1220 : return -ENOMEM;
1221 0 : } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1222 : return 0;
1223 : }
1224 :
1225 : int
1226 0 : copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1227 : {
1228 : pgd_t *src_pgd, *dst_pgd;
1229 : unsigned long next;
1230 0 : unsigned long addr = src_vma->vm_start;
1231 0 : unsigned long end = src_vma->vm_end;
1232 0 : struct mm_struct *dst_mm = dst_vma->vm_mm;
1233 0 : struct mm_struct *src_mm = src_vma->vm_mm;
1234 : struct mmu_notifier_range range;
1235 : bool is_cow;
1236 : int ret;
1237 :
1238 : /*
1239 : * Don't copy ptes where a page fault will fill them correctly.
1240 : * Fork becomes much lighter when there are big shared or private
1241 : * readonly mappings. The tradeoff is that copy_page_range is more
1242 : * efficient than faulting.
1243 : */
1244 0 : if (!(src_vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1245 0 : !src_vma->anon_vma)
1246 : return 0;
1247 :
1248 0 : if (is_vm_hugetlb_page(src_vma))
1249 : return copy_hugetlb_page_range(dst_mm, src_mm, src_vma);
1250 :
1251 : if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1252 : /*
1253 : * We do not free on error cases below as remove_vma
1254 : * gets called on error from higher level routine
1255 : */
1256 : ret = track_pfn_copy(src_vma);
1257 : if (ret)
1258 : return ret;
1259 : }
1260 :
1261 : /*
1262 : * We need to invalidate the secondary MMU mappings only when
1263 : * there could be a permission downgrade on the ptes of the
1264 : * parent mm. And a permission downgrade will only happen if
1265 : * is_cow_mapping() returns true.
1266 : */
1267 0 : is_cow = is_cow_mapping(src_vma->vm_flags);
1268 :
1269 0 : if (is_cow) {
1270 0 : mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1271 : 0, src_vma, src_mm, addr, end);
1272 0 : mmu_notifier_invalidate_range_start(&range);
1273 : /*
1274 : * Disabling preemption is not needed for the write side, as
1275 : * the read side doesn't spin, but goes to the mmap_lock.
1276 : *
1277 : * Use the raw variant of the seqcount_t write API to avoid
1278 : * lockdep complaining about preemptibility.
1279 : */
1280 0 : mmap_assert_write_locked(src_mm);
1281 0 : raw_write_seqcount_begin(&src_mm->write_protect_seq);
1282 : }
1283 :
1284 0 : ret = 0;
1285 0 : dst_pgd = pgd_offset(dst_mm, addr);
1286 0 : src_pgd = pgd_offset(src_mm, addr);
1287 : do {
1288 0 : next = pgd_addr_end(addr, end);
1289 0 : if (pgd_none_or_clear_bad(src_pgd))
1290 : continue;
1291 0 : if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1292 : addr, next))) {
1293 : ret = -ENOMEM;
1294 : break;
1295 : }
1296 0 : } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1297 :
1298 0 : if (is_cow) {
1299 0 : raw_write_seqcount_end(&src_mm->write_protect_seq);
1300 0 : mmu_notifier_invalidate_range_end(&range);
1301 : }
1302 : return ret;
1303 : }
1304 :
1305 : /*
1306 : * Parameter block passed down to zap_pte_range in exceptional cases.
1307 : */
1308 : struct zap_details {
1309 : struct folio *single_folio; /* Locked folio to be unmapped */
1310 : bool even_cows; /* Zap COWed private pages too? */
1311 : };
1312 :
1313 : /* Whether we should zap all COWed (private) pages too */
1314 : static inline bool should_zap_cows(struct zap_details *details)
1315 : {
1316 : /* By default, zap all pages */
1317 0 : if (!details)
1318 : return true;
1319 :
1320 : /* Or, we zap COWed pages only if the caller wants to */
1321 0 : return details->even_cows;
1322 : }
1323 :
1324 : /* Decides whether we should zap this page with the page pointer specified */
1325 0 : static inline bool should_zap_page(struct zap_details *details, struct page *page)
1326 : {
1327 : /* If we can make a decision without *page.. */
1328 0 : if (should_zap_cows(details))
1329 : return true;
1330 :
1331 : /* E.g. the caller passes NULL for the case of a zero page */
1332 0 : if (!page)
1333 : return true;
1334 :
1335 : /* Otherwise we should only zap non-anon pages */
1336 0 : return !PageAnon(page);
1337 : }
1338 :
1339 0 : static unsigned long zap_pte_range(struct mmu_gather *tlb,
1340 : struct vm_area_struct *vma, pmd_t *pmd,
1341 : unsigned long addr, unsigned long end,
1342 : struct zap_details *details)
1343 : {
1344 0 : struct mm_struct *mm = tlb->mm;
1345 0 : int force_flush = 0;
1346 : int rss[NR_MM_COUNTERS];
1347 : spinlock_t *ptl;
1348 : pte_t *start_pte;
1349 : pte_t *pte;
1350 : swp_entry_t entry;
1351 :
1352 0 : tlb_change_page_size(tlb, PAGE_SIZE);
1353 : again:
1354 0 : init_rss_vec(rss);
1355 0 : start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1356 0 : pte = start_pte;
1357 0 : flush_tlb_batched_pending(mm);
1358 : arch_enter_lazy_mmu_mode();
1359 : do {
1360 0 : pte_t ptent = *pte;
1361 : struct page *page;
1362 :
1363 0 : if (pte_none(ptent))
1364 0 : continue;
1365 :
1366 0 : if (need_resched())
1367 : break;
1368 :
1369 0 : if (pte_present(ptent)) {
1370 0 : page = vm_normal_page(vma, addr, ptent);
1371 0 : if (unlikely(!should_zap_page(details, page)))
1372 0 : continue;
1373 0 : ptent = ptep_get_and_clear_full(mm, addr, pte,
1374 0 : tlb->fullmm);
1375 0 : tlb_remove_tlb_entry(tlb, pte, addr);
1376 0 : if (unlikely(!page))
1377 0 : continue;
1378 :
1379 0 : if (!PageAnon(page)) {
1380 0 : if (pte_dirty(ptent)) {
1381 0 : force_flush = 1;
1382 0 : set_page_dirty(page);
1383 : }
1384 0 : if (pte_young(ptent) &&
1385 0 : likely(!(vma->vm_flags & VM_SEQ_READ)))
1386 0 : mark_page_accessed(page);
1387 : }
1388 0 : rss[mm_counter(page)]--;
1389 0 : page_remove_rmap(page, vma, false);
1390 0 : if (unlikely(page_mapcount(page) < 0))
1391 0 : print_bad_pte(vma, addr, ptent, page);
1392 0 : if (unlikely(__tlb_remove_page(tlb, page))) {
1393 : force_flush = 1;
1394 : addr += PAGE_SIZE;
1395 : break;
1396 : }
1397 0 : continue;
1398 : }
1399 :
1400 0 : entry = pte_to_swp_entry(ptent);
1401 0 : if (is_device_private_entry(entry) ||
1402 0 : is_device_exclusive_entry(entry)) {
1403 : page = pfn_swap_entry_to_page(entry);
1404 : if (unlikely(!should_zap_page(details, page)))
1405 : continue;
1406 : rss[mm_counter(page)]--;
1407 : if (is_device_private_entry(entry))
1408 : page_remove_rmap(page, vma, false);
1409 : put_page(page);
1410 0 : } else if (!non_swap_entry(entry)) {
1411 : /* Genuine swap entry, hence a private anon page */
1412 0 : if (!should_zap_cows(details))
1413 0 : continue;
1414 0 : rss[MM_SWAPENTS]--;
1415 0 : if (unlikely(!free_swap_and_cache(entry)))
1416 0 : print_bad_pte(vma, addr, ptent, NULL);
1417 0 : } else if (is_migration_entry(entry)) {
1418 0 : page = pfn_swap_entry_to_page(entry);
1419 0 : if (!should_zap_page(details, page))
1420 0 : continue;
1421 0 : rss[mm_counter(page)]--;
1422 0 : } else if (is_hwpoison_entry(entry)) {
1423 : if (!should_zap_cows(details))
1424 : continue;
1425 : } else {
1426 : /* We should have covered all the swap entry types */
1427 0 : WARN_ON_ONCE(1);
1428 : }
1429 0 : pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1430 0 : } while (pte++, addr += PAGE_SIZE, addr != end);
1431 :
1432 0 : add_mm_rss_vec(mm, rss);
1433 : arch_leave_lazy_mmu_mode();
1434 :
1435 : /* Do the actual TLB flush before dropping ptl */
1436 0 : if (force_flush)
1437 0 : tlb_flush_mmu_tlbonly(tlb);
1438 0 : pte_unmap_unlock(start_pte, ptl);
1439 :
1440 : /*
1441 : * If we forced a TLB flush (either due to running out of
1442 : * batch buffers or because we needed to flush dirty TLB
1443 : * entries before releasing the ptl), free the batched
1444 : * memory too. Restart if we didn't do everything.
1445 : */
1446 0 : if (force_flush) {
1447 0 : force_flush = 0;
1448 0 : tlb_flush_mmu(tlb);
1449 : }
1450 :
1451 0 : if (addr != end) {
1452 0 : cond_resched();
1453 0 : goto again;
1454 : }
1455 :
1456 0 : return addr;
1457 : }
1458 :
1459 0 : static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1460 : struct vm_area_struct *vma, pud_t *pud,
1461 : unsigned long addr, unsigned long end,
1462 : struct zap_details *details)
1463 : {
1464 : pmd_t *pmd;
1465 : unsigned long next;
1466 :
1467 0 : pmd = pmd_offset(pud, addr);
1468 : do {
1469 0 : next = pmd_addr_end(addr, end);
1470 0 : if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1471 : if (next - addr != HPAGE_PMD_SIZE)
1472 : __split_huge_pmd(vma, pmd, addr, false, NULL);
1473 : else if (zap_huge_pmd(tlb, vma, pmd, addr))
1474 : goto next;
1475 : /* fall through */
1476 : } else if (details && details->single_folio &&
1477 : folio_test_pmd_mappable(details->single_folio) &&
1478 : next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1479 : spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1480 : /*
1481 : * Take and drop THP pmd lock so that we cannot return
1482 : * prematurely, while zap_huge_pmd() has cleared *pmd,
1483 : * but not yet decremented compound_mapcount().
1484 : */
1485 : spin_unlock(ptl);
1486 : }
1487 :
1488 : /*
1489 : * Here there can be other concurrent MADV_DONTNEED or
1490 : * trans huge page faults running, and if the pmd is
1491 : * none or trans huge it can change under us. This is
1492 : * because MADV_DONTNEED holds the mmap_lock in read
1493 : * mode.
1494 : */
1495 0 : if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1496 : goto next;
1497 0 : next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1498 : next:
1499 0 : cond_resched();
1500 0 : } while (pmd++, addr = next, addr != end);
1501 :
1502 0 : return addr;
1503 : }
1504 :
1505 0 : static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1506 : struct vm_area_struct *vma, p4d_t *p4d,
1507 : unsigned long addr, unsigned long end,
1508 : struct zap_details *details)
1509 : {
1510 : pud_t *pud;
1511 : unsigned long next;
1512 :
1513 0 : pud = pud_offset(p4d, addr);
1514 : do {
1515 0 : next = pud_addr_end(addr, end);
1516 0 : if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1517 : if (next - addr != HPAGE_PUD_SIZE) {
1518 : mmap_assert_locked(tlb->mm);
1519 : split_huge_pud(vma, pud, addr);
1520 : } else if (zap_huge_pud(tlb, vma, pud, addr))
1521 : goto next;
1522 : /* fall through */
1523 : }
1524 0 : if (pud_none_or_clear_bad(pud))
1525 0 : continue;
1526 0 : next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1527 : next:
1528 0 : cond_resched();
1529 0 : } while (pud++, addr = next, addr != end);
1530 :
1531 0 : return addr;
1532 : }
1533 :
1534 : static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1535 : struct vm_area_struct *vma, pgd_t *pgd,
1536 : unsigned long addr, unsigned long end,
1537 : struct zap_details *details)
1538 : {
1539 : p4d_t *p4d;
1540 : unsigned long next;
1541 :
1542 : p4d = p4d_offset(pgd, addr);
1543 : do {
1544 0 : next = p4d_addr_end(addr, end);
1545 0 : if (p4d_none_or_clear_bad(p4d))
1546 : continue;
1547 0 : next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1548 0 : } while (p4d++, addr = next, addr != end);
1549 :
1550 : return addr;
1551 : }
1552 :
1553 0 : void unmap_page_range(struct mmu_gather *tlb,
1554 : struct vm_area_struct *vma,
1555 : unsigned long addr, unsigned long end,
1556 : struct zap_details *details)
1557 : {
1558 : pgd_t *pgd;
1559 : unsigned long next;
1560 :
1561 0 : BUG_ON(addr >= end);
1562 0 : tlb_start_vma(tlb, vma);
1563 0 : pgd = pgd_offset(vma->vm_mm, addr);
1564 : do {
1565 0 : next = pgd_addr_end(addr, end);
1566 0 : if (pgd_none_or_clear_bad(pgd))
1567 : continue;
1568 0 : next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1569 0 : } while (pgd++, addr = next, addr != end);
1570 0 : tlb_end_vma(tlb, vma);
1571 0 : }
1572 :
1573 :
1574 0 : static void unmap_single_vma(struct mmu_gather *tlb,
1575 : struct vm_area_struct *vma, unsigned long start_addr,
1576 : unsigned long end_addr,
1577 : struct zap_details *details)
1578 : {
1579 0 : unsigned long start = max(vma->vm_start, start_addr);
1580 : unsigned long end;
1581 :
1582 0 : if (start >= vma->vm_end)
1583 : return;
1584 0 : end = min(vma->vm_end, end_addr);
1585 0 : if (end <= vma->vm_start)
1586 : return;
1587 :
1588 : if (vma->vm_file)
1589 : uprobe_munmap(vma, start, end);
1590 :
1591 : if (unlikely(vma->vm_flags & VM_PFNMAP))
1592 : untrack_pfn(vma, 0, 0);
1593 :
1594 0 : if (start != end) {
1595 0 : if (unlikely(is_vm_hugetlb_page(vma))) {
1596 : /*
1597 : * It is undesirable to test vma->vm_file as it
1598 : * should be non-null for valid hugetlb area.
1599 : * However, vm_file will be NULL in the error
1600 : * cleanup path of mmap_region. When
1601 : * hugetlbfs ->mmap method fails,
1602 : * mmap_region() nullifies vma->vm_file
1603 : * before calling this function to clean up.
1604 : * Since no pte has actually been setup, it is
1605 : * safe to do nothing in this case.
1606 : */
1607 : if (vma->vm_file) {
1608 : i_mmap_lock_write(vma->vm_file->f_mapping);
1609 : __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1610 : i_mmap_unlock_write(vma->vm_file->f_mapping);
1611 : }
1612 : } else
1613 0 : unmap_page_range(tlb, vma, start, end, details);
1614 : }
1615 : }
1616 :
1617 : /**
1618 : * unmap_vmas - unmap a range of memory covered by a list of vma's
1619 : * @tlb: address of the caller's struct mmu_gather
1620 : * @vma: the starting vma
1621 : * @start_addr: virtual address at which to start unmapping
1622 : * @end_addr: virtual address at which to end unmapping
1623 : *
1624 : * Unmap all pages in the vma list.
1625 : *
1626 : * Only addresses between `start' and `end' will be unmapped.
1627 : *
1628 : * The VMA list must be sorted in ascending virtual address order.
1629 : *
1630 : * unmap_vmas() assumes that the caller will flush the whole unmapped address
1631 : * range after unmap_vmas() returns. So the only responsibility here is to
1632 : * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1633 : * drops the lock and schedules.
1634 : */
1635 0 : void unmap_vmas(struct mmu_gather *tlb,
1636 : struct vm_area_struct *vma, unsigned long start_addr,
1637 : unsigned long end_addr)
1638 : {
1639 : struct mmu_notifier_range range;
1640 :
1641 : mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1642 : start_addr, end_addr);
1643 : mmu_notifier_invalidate_range_start(&range);
1644 0 : for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1645 0 : unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1646 0 : mmu_notifier_invalidate_range_end(&range);
1647 0 : }
1648 :
1649 : /**
1650 : * zap_page_range - remove user pages in a given range
1651 : * @vma: vm_area_struct holding the applicable pages
1652 : * @start: starting address of pages to zap
1653 : * @size: number of bytes to zap
1654 : *
1655 : * Caller must protect the VMA list
1656 : */
1657 0 : void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1658 : unsigned long size)
1659 : {
1660 : struct mmu_notifier_range range;
1661 : struct mmu_gather tlb;
1662 :
1663 0 : lru_add_drain();
1664 0 : mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1665 : start, start + size);
1666 0 : tlb_gather_mmu(&tlb, vma->vm_mm);
1667 0 : update_hiwater_rss(vma->vm_mm);
1668 : mmu_notifier_invalidate_range_start(&range);
1669 0 : for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
1670 0 : unmap_single_vma(&tlb, vma, start, range.end, NULL);
1671 0 : mmu_notifier_invalidate_range_end(&range);
1672 0 : tlb_finish_mmu(&tlb);
1673 0 : }
1674 :
1675 : /**
1676 : * zap_page_range_single - remove user pages in a given range
1677 : * @vma: vm_area_struct holding the applicable pages
1678 : * @address: starting address of pages to zap
1679 : * @size: number of bytes to zap
1680 : * @details: details of shared cache invalidation
1681 : *
1682 : * The range must fit into one VMA.
1683 : */
1684 0 : static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1685 : unsigned long size, struct zap_details *details)
1686 : {
1687 : struct mmu_notifier_range range;
1688 : struct mmu_gather tlb;
1689 :
1690 0 : lru_add_drain();
1691 0 : mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1692 : address, address + size);
1693 0 : tlb_gather_mmu(&tlb, vma->vm_mm);
1694 0 : update_hiwater_rss(vma->vm_mm);
1695 0 : mmu_notifier_invalidate_range_start(&range);
1696 0 : unmap_single_vma(&tlb, vma, address, range.end, details);
1697 0 : mmu_notifier_invalidate_range_end(&range);
1698 0 : tlb_finish_mmu(&tlb);
1699 0 : }
1700 :
1701 : /**
1702 : * zap_vma_ptes - remove ptes mapping the vma
1703 : * @vma: vm_area_struct holding ptes to be zapped
1704 : * @address: starting address of pages to zap
1705 : * @size: number of bytes to zap
1706 : *
1707 : * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1708 : *
1709 : * The entire address range must be fully contained within the vma.
1710 : *
1711 : */
1712 0 : void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1713 : unsigned long size)
1714 : {
1715 0 : if (!range_in_vma(vma, address, address + size) ||
1716 0 : !(vma->vm_flags & VM_PFNMAP))
1717 : return;
1718 :
1719 0 : zap_page_range_single(vma, address, size, NULL);
1720 : }
1721 : EXPORT_SYMBOL_GPL(zap_vma_ptes);
1722 :
1723 0 : static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1724 : {
1725 : pgd_t *pgd;
1726 : p4d_t *p4d;
1727 : pud_t *pud;
1728 : pmd_t *pmd;
1729 :
1730 0 : pgd = pgd_offset(mm, addr);
1731 0 : p4d = p4d_alloc(mm, pgd, addr);
1732 0 : if (!p4d)
1733 : return NULL;
1734 0 : pud = pud_alloc(mm, p4d, addr);
1735 : if (!pud)
1736 : return NULL;
1737 0 : pmd = pmd_alloc(mm, pud, addr);
1738 0 : if (!pmd)
1739 : return NULL;
1740 :
1741 : VM_BUG_ON(pmd_trans_huge(*pmd));
1742 0 : return pmd;
1743 : }
1744 :
1745 0 : pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1746 : spinlock_t **ptl)
1747 : {
1748 0 : pmd_t *pmd = walk_to_pmd(mm, addr);
1749 :
1750 0 : if (!pmd)
1751 : return NULL;
1752 0 : return pte_alloc_map_lock(mm, pmd, addr, ptl);
1753 : }
1754 :
1755 0 : static int validate_page_before_insert(struct page *page)
1756 : {
1757 0 : if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1758 : return -EINVAL;
1759 : flush_dcache_page(page);
1760 : return 0;
1761 : }
1762 :
1763 0 : static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
1764 : unsigned long addr, struct page *page, pgprot_t prot)
1765 : {
1766 0 : if (!pte_none(*pte))
1767 : return -EBUSY;
1768 : /* Ok, finally just insert the thing.. */
1769 0 : get_page(page);
1770 0 : inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
1771 0 : page_add_file_rmap(page, vma, false);
1772 0 : set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
1773 : return 0;
1774 : }
1775 :
1776 : /*
1777 : * This is the old fallback for page remapping.
1778 : *
1779 : * For historical reasons, it only allows reserved pages. Only
1780 : * old drivers should use this, and they needed to mark their
1781 : * pages reserved for the old functions anyway.
1782 : */
1783 0 : static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1784 : struct page *page, pgprot_t prot)
1785 : {
1786 : int retval;
1787 : pte_t *pte;
1788 : spinlock_t *ptl;
1789 :
1790 0 : retval = validate_page_before_insert(page);
1791 0 : if (retval)
1792 : goto out;
1793 0 : retval = -ENOMEM;
1794 0 : pte = get_locked_pte(vma->vm_mm, addr, &ptl);
1795 0 : if (!pte)
1796 : goto out;
1797 0 : retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
1798 0 : pte_unmap_unlock(pte, ptl);
1799 : out:
1800 0 : return retval;
1801 : }
1802 :
1803 : #ifdef pte_index
1804 0 : static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
1805 : unsigned long addr, struct page *page, pgprot_t prot)
1806 : {
1807 : int err;
1808 :
1809 0 : if (!page_count(page))
1810 : return -EINVAL;
1811 0 : err = validate_page_before_insert(page);
1812 0 : if (err)
1813 : return err;
1814 0 : return insert_page_into_pte_locked(vma, pte, addr, page, prot);
1815 : }
1816 :
1817 : /* insert_pages() amortizes the cost of spinlock operations
1818 : * when inserting pages in a loop. Arch *must* define pte_index.
1819 : */
1820 0 : static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1821 : struct page **pages, unsigned long *num, pgprot_t prot)
1822 : {
1823 0 : pmd_t *pmd = NULL;
1824 : pte_t *start_pte, *pte;
1825 : spinlock_t *pte_lock;
1826 0 : struct mm_struct *const mm = vma->vm_mm;
1827 0 : unsigned long curr_page_idx = 0;
1828 0 : unsigned long remaining_pages_total = *num;
1829 : unsigned long pages_to_write_in_pmd;
1830 : int ret;
1831 : more:
1832 0 : ret = -EFAULT;
1833 0 : pmd = walk_to_pmd(mm, addr);
1834 0 : if (!pmd)
1835 : goto out;
1836 :
1837 0 : pages_to_write_in_pmd = min_t(unsigned long,
1838 : remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1839 :
1840 : /* Allocate the PTE if necessary; takes PMD lock once only. */
1841 0 : ret = -ENOMEM;
1842 0 : if (pte_alloc(mm, pmd))
1843 : goto out;
1844 :
1845 0 : while (pages_to_write_in_pmd) {
1846 0 : int pte_idx = 0;
1847 0 : const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1848 :
1849 0 : start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1850 0 : for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1851 0 : int err = insert_page_in_batch_locked(vma, pte,
1852 0 : addr, pages[curr_page_idx], prot);
1853 0 : if (unlikely(err)) {
1854 0 : pte_unmap_unlock(start_pte, pte_lock);
1855 0 : ret = err;
1856 0 : remaining_pages_total -= pte_idx;
1857 0 : goto out;
1858 : }
1859 0 : addr += PAGE_SIZE;
1860 0 : ++curr_page_idx;
1861 : }
1862 0 : pte_unmap_unlock(start_pte, pte_lock);
1863 0 : pages_to_write_in_pmd -= batch_size;
1864 0 : remaining_pages_total -= batch_size;
1865 : }
1866 0 : if (remaining_pages_total)
1867 : goto more;
1868 : ret = 0;
1869 : out:
1870 0 : *num = remaining_pages_total;
1871 0 : return ret;
1872 : }
1873 : #endif /* ifdef pte_index */
1874 :
1875 : /**
1876 : * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1877 : * @vma: user vma to map to
1878 : * @addr: target start user address of these pages
1879 : * @pages: source kernel pages
1880 : * @num: in: number of pages to map. out: number of pages that were *not*
1881 : * mapped. (0 means all pages were successfully mapped).
1882 : *
1883 : * Preferred over vm_insert_page() when inserting multiple pages.
1884 : *
1885 : * In case of error, we may have mapped a subset of the provided
1886 : * pages. It is the caller's responsibility to account for this case.
1887 : *
1888 : * The same restrictions apply as in vm_insert_page().
1889 : */
1890 0 : int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1891 : struct page **pages, unsigned long *num)
1892 : {
1893 : #ifdef pte_index
1894 0 : const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1895 :
1896 0 : if (addr < vma->vm_start || end_addr >= vma->vm_end)
1897 : return -EFAULT;
1898 0 : if (!(vma->vm_flags & VM_MIXEDMAP)) {
1899 0 : BUG_ON(mmap_read_trylock(vma->vm_mm));
1900 0 : BUG_ON(vma->vm_flags & VM_PFNMAP);
1901 0 : vma->vm_flags |= VM_MIXEDMAP;
1902 : }
1903 : /* Defer page refcount checking till we're about to map that page. */
1904 0 : return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
1905 : #else
1906 : unsigned long idx = 0, pgcount = *num;
1907 : int err = -EINVAL;
1908 :
1909 : for (; idx < pgcount; ++idx) {
1910 : err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
1911 : if (err)
1912 : break;
1913 : }
1914 : *num = pgcount - idx;
1915 : return err;
1916 : #endif /* ifdef pte_index */
1917 : }
1918 : EXPORT_SYMBOL(vm_insert_pages);
1919 :
1920 : /**
1921 : * vm_insert_page - insert single page into user vma
1922 : * @vma: user vma to map to
1923 : * @addr: target user address of this page
1924 : * @page: source kernel page
1925 : *
1926 : * This allows drivers to insert individual pages they've allocated
1927 : * into a user vma.
1928 : *
1929 : * The page has to be a nice clean _individual_ kernel allocation.
1930 : * If you allocate a compound page, you need to have marked it as
1931 : * such (__GFP_COMP), or manually just split the page up yourself
1932 : * (see split_page()).
1933 : *
1934 : * NOTE! Traditionally this was done with "remap_pfn_range()" which
1935 : * took an arbitrary page protection parameter. This doesn't allow
1936 : * that. Your vma protection will have to be set up correctly, which
1937 : * means that if you want a shared writable mapping, you'd better
1938 : * ask for a shared writable mapping!
1939 : *
1940 : * The page does not need to be reserved.
1941 : *
1942 : * Usually this function is called from f_op->mmap() handler
1943 : * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1944 : * Caller must set VM_MIXEDMAP on vma if it wants to call this
1945 : * function from other places, for example from page-fault handler.
1946 : *
1947 : * Return: %0 on success, negative error code otherwise.
1948 : */
1949 0 : int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1950 : struct page *page)
1951 : {
1952 0 : if (addr < vma->vm_start || addr >= vma->vm_end)
1953 : return -EFAULT;
1954 0 : if (!page_count(page))
1955 : return -EINVAL;
1956 0 : if (!(vma->vm_flags & VM_MIXEDMAP)) {
1957 0 : BUG_ON(mmap_read_trylock(vma->vm_mm));
1958 0 : BUG_ON(vma->vm_flags & VM_PFNMAP);
1959 0 : vma->vm_flags |= VM_MIXEDMAP;
1960 : }
1961 0 : return insert_page(vma, addr, page, vma->vm_page_prot);
1962 : }
1963 : EXPORT_SYMBOL(vm_insert_page);
1964 :
1965 : /*
1966 : * __vm_map_pages - maps range of kernel pages into user vma
1967 : * @vma: user vma to map to
1968 : * @pages: pointer to array of source kernel pages
1969 : * @num: number of pages in page array
1970 : * @offset: user's requested vm_pgoff
1971 : *
1972 : * This allows drivers to map range of kernel pages into a user vma.
1973 : *
1974 : * Return: 0 on success and error code otherwise.
1975 : */
1976 0 : static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1977 : unsigned long num, unsigned long offset)
1978 : {
1979 0 : unsigned long count = vma_pages(vma);
1980 0 : unsigned long uaddr = vma->vm_start;
1981 : int ret, i;
1982 :
1983 : /* Fail if the user requested offset is beyond the end of the object */
1984 0 : if (offset >= num)
1985 : return -ENXIO;
1986 :
1987 : /* Fail if the user requested size exceeds available object size */
1988 0 : if (count > num - offset)
1989 : return -ENXIO;
1990 :
1991 0 : for (i = 0; i < count; i++) {
1992 0 : ret = vm_insert_page(vma, uaddr, pages[offset + i]);
1993 0 : if (ret < 0)
1994 : return ret;
1995 0 : uaddr += PAGE_SIZE;
1996 : }
1997 :
1998 : return 0;
1999 : }
2000 :
2001 : /**
2002 : * vm_map_pages - maps range of kernel pages starts with non zero offset
2003 : * @vma: user vma to map to
2004 : * @pages: pointer to array of source kernel pages
2005 : * @num: number of pages in page array
2006 : *
2007 : * Maps an object consisting of @num pages, catering for the user's
2008 : * requested vm_pgoff
2009 : *
2010 : * If we fail to insert any page into the vma, the function will return
2011 : * immediately leaving any previously inserted pages present. Callers
2012 : * from the mmap handler may immediately return the error as their caller
2013 : * will destroy the vma, removing any successfully inserted pages. Other
2014 : * callers should make their own arrangements for calling unmap_region().
2015 : *
2016 : * Context: Process context. Called by mmap handlers.
2017 : * Return: 0 on success and error code otherwise.
2018 : */
2019 0 : int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2020 : unsigned long num)
2021 : {
2022 0 : return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2023 : }
2024 : EXPORT_SYMBOL(vm_map_pages);
2025 :
2026 : /**
2027 : * vm_map_pages_zero - map range of kernel pages starts with zero offset
2028 : * @vma: user vma to map to
2029 : * @pages: pointer to array of source kernel pages
2030 : * @num: number of pages in page array
2031 : *
2032 : * Similar to vm_map_pages(), except that it explicitly sets the offset
2033 : * to 0. This function is intended for the drivers that did not consider
2034 : * vm_pgoff.
2035 : *
2036 : * Context: Process context. Called by mmap handlers.
2037 : * Return: 0 on success and error code otherwise.
2038 : */
2039 0 : int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2040 : unsigned long num)
2041 : {
2042 0 : return __vm_map_pages(vma, pages, num, 0);
2043 : }
2044 : EXPORT_SYMBOL(vm_map_pages_zero);
2045 :
2046 0 : static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2047 : pfn_t pfn, pgprot_t prot, bool mkwrite)
2048 : {
2049 0 : struct mm_struct *mm = vma->vm_mm;
2050 : pte_t *pte, entry;
2051 : spinlock_t *ptl;
2052 :
2053 0 : pte = get_locked_pte(mm, addr, &ptl);
2054 0 : if (!pte)
2055 : return VM_FAULT_OOM;
2056 0 : if (!pte_none(*pte)) {
2057 0 : if (mkwrite) {
2058 : /*
2059 : * For read faults on private mappings the PFN passed
2060 : * in may not match the PFN we have mapped if the
2061 : * mapped PFN is a writeable COW page. In the mkwrite
2062 : * case we are creating a writable PTE for a shared
2063 : * mapping and we expect the PFNs to match. If they
2064 : * don't match, we are likely racing with block
2065 : * allocation and mapping invalidation so just skip the
2066 : * update.
2067 : */
2068 0 : if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
2069 0 : WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
2070 : goto out_unlock;
2071 : }
2072 0 : entry = pte_mkyoung(*pte);
2073 0 : entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2074 0 : if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2075 : update_mmu_cache(vma, addr, pte);
2076 : }
2077 : goto out_unlock;
2078 : }
2079 :
2080 : /* Ok, finally just insert the thing.. */
2081 0 : if (pfn_t_devmap(pfn))
2082 : entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2083 : else
2084 0 : entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2085 :
2086 0 : if (mkwrite) {
2087 0 : entry = pte_mkyoung(entry);
2088 0 : entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2089 : }
2090 :
2091 0 : set_pte_at(mm, addr, pte, entry);
2092 : update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2093 :
2094 : out_unlock:
2095 0 : pte_unmap_unlock(pte, ptl);
2096 0 : return VM_FAULT_NOPAGE;
2097 : }
2098 :
2099 : /**
2100 : * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2101 : * @vma: user vma to map to
2102 : * @addr: target user address of this page
2103 : * @pfn: source kernel pfn
2104 : * @pgprot: pgprot flags for the inserted page
2105 : *
2106 : * This is exactly like vmf_insert_pfn(), except that it allows drivers
2107 : * to override pgprot on a per-page basis.
2108 : *
2109 : * This only makes sense for IO mappings, and it makes no sense for
2110 : * COW mappings. In general, using multiple vmas is preferable;
2111 : * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2112 : * impractical.
2113 : *
2114 : * See vmf_insert_mixed_prot() for a discussion of the implication of using
2115 : * a value of @pgprot different from that of @vma->vm_page_prot.
2116 : *
2117 : * Context: Process context. May allocate using %GFP_KERNEL.
2118 : * Return: vm_fault_t value.
2119 : */
2120 0 : vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2121 : unsigned long pfn, pgprot_t pgprot)
2122 : {
2123 : /*
2124 : * Technically, architectures with pte_special can avoid all these
2125 : * restrictions (same for remap_pfn_range). However we would like
2126 : * consistency in testing and feature parity among all, so we should
2127 : * try to keep these invariants in place for everybody.
2128 : */
2129 0 : BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2130 0 : BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2131 : (VM_PFNMAP|VM_MIXEDMAP));
2132 0 : BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2133 0 : BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2134 :
2135 0 : if (addr < vma->vm_start || addr >= vma->vm_end)
2136 : return VM_FAULT_SIGBUS;
2137 :
2138 0 : if (!pfn_modify_allowed(pfn, pgprot))
2139 : return VM_FAULT_SIGBUS;
2140 :
2141 0 : track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2142 :
2143 0 : return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2144 : false);
2145 : }
2146 : EXPORT_SYMBOL(vmf_insert_pfn_prot);
2147 :
2148 : /**
2149 : * vmf_insert_pfn - insert single pfn into user vma
2150 : * @vma: user vma to map to
2151 : * @addr: target user address of this page
2152 : * @pfn: source kernel pfn
2153 : *
2154 : * Similar to vm_insert_page, this allows drivers to insert individual pages
2155 : * they've allocated into a user vma. Same comments apply.
2156 : *
2157 : * This function should only be called from a vm_ops->fault handler, and
2158 : * in that case the handler should return the result of this function.
2159 : *
2160 : * vma cannot be a COW mapping.
2161 : *
2162 : * As this is called only for pages that do not currently exist, we
2163 : * do not need to flush old virtual caches or the TLB.
2164 : *
2165 : * Context: Process context. May allocate using %GFP_KERNEL.
2166 : * Return: vm_fault_t value.
2167 : */
2168 0 : vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2169 : unsigned long pfn)
2170 : {
2171 0 : return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2172 : }
2173 : EXPORT_SYMBOL(vmf_insert_pfn);
2174 :
2175 : static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2176 : {
2177 : /* these checks mirror the abort conditions in vm_normal_page */
2178 0 : if (vma->vm_flags & VM_MIXEDMAP)
2179 : return true;
2180 0 : if (pfn_t_devmap(pfn))
2181 : return true;
2182 0 : if (pfn_t_special(pfn))
2183 : return true;
2184 0 : if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2185 : return true;
2186 : return false;
2187 : }
2188 :
2189 0 : static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2190 : unsigned long addr, pfn_t pfn, pgprot_t pgprot,
2191 : bool mkwrite)
2192 : {
2193 : int err;
2194 :
2195 0 : BUG_ON(!vm_mixed_ok(vma, pfn));
2196 :
2197 0 : if (addr < vma->vm_start || addr >= vma->vm_end)
2198 : return VM_FAULT_SIGBUS;
2199 :
2200 0 : track_pfn_insert(vma, &pgprot, pfn);
2201 :
2202 0 : if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2203 : return VM_FAULT_SIGBUS;
2204 :
2205 : /*
2206 : * If we don't have pte special, then we have to use the pfn_valid()
2207 : * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2208 : * refcount the page if pfn_valid is true (hence insert_page rather
2209 : * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2210 : * without pte special, it would there be refcounted as a normal page.
2211 : */
2212 : if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2213 0 : !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2214 : struct page *page;
2215 :
2216 : /*
2217 : * At this point we are committed to insert_page()
2218 : * regardless of whether the caller specified flags that
2219 : * result in pfn_t_has_page() == false.
2220 : */
2221 0 : page = pfn_to_page(pfn_t_to_pfn(pfn));
2222 0 : err = insert_page(vma, addr, page, pgprot);
2223 : } else {
2224 0 : return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2225 : }
2226 :
2227 0 : if (err == -ENOMEM)
2228 : return VM_FAULT_OOM;
2229 0 : if (err < 0 && err != -EBUSY)
2230 : return VM_FAULT_SIGBUS;
2231 :
2232 0 : return VM_FAULT_NOPAGE;
2233 : }
2234 :
2235 : /**
2236 : * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2237 : * @vma: user vma to map to
2238 : * @addr: target user address of this page
2239 : * @pfn: source kernel pfn
2240 : * @pgprot: pgprot flags for the inserted page
2241 : *
2242 : * This is exactly like vmf_insert_mixed(), except that it allows drivers
2243 : * to override pgprot on a per-page basis.
2244 : *
2245 : * Typically this function should be used by drivers to set caching- and
2246 : * encryption bits different than those of @vma->vm_page_prot, because
2247 : * the caching- or encryption mode may not be known at mmap() time.
2248 : * This is ok as long as @vma->vm_page_prot is not used by the core vm
2249 : * to set caching and encryption bits for those vmas (except for COW pages).
2250 : * This is ensured by core vm only modifying these page table entries using
2251 : * functions that don't touch caching- or encryption bits, using pte_modify()
2252 : * if needed. (See for example mprotect()).
2253 : * Also when new page-table entries are created, this is only done using the
2254 : * fault() callback, and never using the value of vma->vm_page_prot,
2255 : * except for page-table entries that point to anonymous pages as the result
2256 : * of COW.
2257 : *
2258 : * Context: Process context. May allocate using %GFP_KERNEL.
2259 : * Return: vm_fault_t value.
2260 : */
2261 0 : vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
2262 : pfn_t pfn, pgprot_t pgprot)
2263 : {
2264 0 : return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
2265 : }
2266 : EXPORT_SYMBOL(vmf_insert_mixed_prot);
2267 :
2268 0 : vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2269 : pfn_t pfn)
2270 : {
2271 0 : return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
2272 : }
2273 : EXPORT_SYMBOL(vmf_insert_mixed);
2274 :
2275 : /*
2276 : * If the insertion of PTE failed because someone else already added a
2277 : * different entry in the mean time, we treat that as success as we assume
2278 : * the same entry was actually inserted.
2279 : */
2280 0 : vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2281 : unsigned long addr, pfn_t pfn)
2282 : {
2283 0 : return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
2284 : }
2285 : EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2286 :
2287 : /*
2288 : * maps a range of physical memory into the requested pages. the old
2289 : * mappings are removed. any references to nonexistent pages results
2290 : * in null mappings (currently treated as "copy-on-access")
2291 : */
2292 0 : static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2293 : unsigned long addr, unsigned long end,
2294 : unsigned long pfn, pgprot_t prot)
2295 : {
2296 : pte_t *pte, *mapped_pte;
2297 : spinlock_t *ptl;
2298 0 : int err = 0;
2299 :
2300 0 : mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2301 0 : if (!pte)
2302 : return -ENOMEM;
2303 : arch_enter_lazy_mmu_mode();
2304 : do {
2305 0 : BUG_ON(!pte_none(*pte));
2306 0 : if (!pfn_modify_allowed(pfn, prot)) {
2307 : err = -EACCES;
2308 : break;
2309 : }
2310 0 : set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2311 0 : pfn++;
2312 0 : } while (pte++, addr += PAGE_SIZE, addr != end);
2313 : arch_leave_lazy_mmu_mode();
2314 0 : pte_unmap_unlock(mapped_pte, ptl);
2315 0 : return err;
2316 : }
2317 :
2318 0 : static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2319 : unsigned long addr, unsigned long end,
2320 : unsigned long pfn, pgprot_t prot)
2321 : {
2322 : pmd_t *pmd;
2323 : unsigned long next;
2324 : int err;
2325 :
2326 0 : pfn -= addr >> PAGE_SHIFT;
2327 0 : pmd = pmd_alloc(mm, pud, addr);
2328 0 : if (!pmd)
2329 : return -ENOMEM;
2330 : VM_BUG_ON(pmd_trans_huge(*pmd));
2331 : do {
2332 0 : next = pmd_addr_end(addr, end);
2333 0 : err = remap_pte_range(mm, pmd, addr, next,
2334 0 : pfn + (addr >> PAGE_SHIFT), prot);
2335 0 : if (err)
2336 : return err;
2337 0 : } while (pmd++, addr = next, addr != end);
2338 : return 0;
2339 : }
2340 :
2341 : static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2342 : unsigned long addr, unsigned long end,
2343 : unsigned long pfn, pgprot_t prot)
2344 : {
2345 : pud_t *pud;
2346 : unsigned long next;
2347 : int err;
2348 :
2349 0 : pfn -= addr >> PAGE_SHIFT;
2350 0 : pud = pud_alloc(mm, p4d, addr);
2351 : if (!pud)
2352 : return -ENOMEM;
2353 : do {
2354 0 : next = pud_addr_end(addr, end);
2355 0 : err = remap_pmd_range(mm, pud, addr, next,
2356 : pfn + (addr >> PAGE_SHIFT), prot);
2357 0 : if (err)
2358 : return err;
2359 0 : } while (pud++, addr = next, addr != end);
2360 : return 0;
2361 : }
2362 :
2363 0 : static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2364 : unsigned long addr, unsigned long end,
2365 : unsigned long pfn, pgprot_t prot)
2366 : {
2367 : p4d_t *p4d;
2368 : unsigned long next;
2369 : int err;
2370 :
2371 0 : pfn -= addr >> PAGE_SHIFT;
2372 0 : p4d = p4d_alloc(mm, pgd, addr);
2373 0 : if (!p4d)
2374 : return -ENOMEM;
2375 : do {
2376 0 : next = p4d_addr_end(addr, end);
2377 0 : err = remap_pud_range(mm, p4d, addr, next,
2378 : pfn + (addr >> PAGE_SHIFT), prot);
2379 0 : if (err)
2380 : return err;
2381 0 : } while (p4d++, addr = next, addr != end);
2382 0 : return 0;
2383 : }
2384 :
2385 : /*
2386 : * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2387 : * must have pre-validated the caching bits of the pgprot_t.
2388 : */
2389 0 : int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2390 : unsigned long pfn, unsigned long size, pgprot_t prot)
2391 : {
2392 : pgd_t *pgd;
2393 : unsigned long next;
2394 0 : unsigned long end = addr + PAGE_ALIGN(size);
2395 0 : struct mm_struct *mm = vma->vm_mm;
2396 : int err;
2397 :
2398 0 : if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2399 : return -EINVAL;
2400 :
2401 : /*
2402 : * Physically remapped pages are special. Tell the
2403 : * rest of the world about it:
2404 : * VM_IO tells people not to look at these pages
2405 : * (accesses can have side effects).
2406 : * VM_PFNMAP tells the core MM that the base pages are just
2407 : * raw PFN mappings, and do not have a "struct page" associated
2408 : * with them.
2409 : * VM_DONTEXPAND
2410 : * Disable vma merging and expanding with mremap().
2411 : * VM_DONTDUMP
2412 : * Omit vma from core dump, even when VM_IO turned off.
2413 : *
2414 : * There's a horrible special case to handle copy-on-write
2415 : * behaviour that some programs depend on. We mark the "original"
2416 : * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2417 : * See vm_normal_page() for details.
2418 : */
2419 0 : if (is_cow_mapping(vma->vm_flags)) {
2420 0 : if (addr != vma->vm_start || end != vma->vm_end)
2421 : return -EINVAL;
2422 0 : vma->vm_pgoff = pfn;
2423 : }
2424 :
2425 0 : vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2426 :
2427 0 : BUG_ON(addr >= end);
2428 0 : pfn -= addr >> PAGE_SHIFT;
2429 0 : pgd = pgd_offset(mm, addr);
2430 0 : flush_cache_range(vma, addr, end);
2431 : do {
2432 0 : next = pgd_addr_end(addr, end);
2433 0 : err = remap_p4d_range(mm, pgd, addr, next,
2434 0 : pfn + (addr >> PAGE_SHIFT), prot);
2435 0 : if (err)
2436 : return err;
2437 0 : } while (pgd++, addr = next, addr != end);
2438 :
2439 : return 0;
2440 : }
2441 :
2442 : /**
2443 : * remap_pfn_range - remap kernel memory to userspace
2444 : * @vma: user vma to map to
2445 : * @addr: target page aligned user address to start at
2446 : * @pfn: page frame number of kernel physical memory address
2447 : * @size: size of mapping area
2448 : * @prot: page protection flags for this mapping
2449 : *
2450 : * Note: this is only safe if the mm semaphore is held when called.
2451 : *
2452 : * Return: %0 on success, negative error code otherwise.
2453 : */
2454 0 : int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2455 : unsigned long pfn, unsigned long size, pgprot_t prot)
2456 : {
2457 : int err;
2458 :
2459 0 : err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2460 : if (err)
2461 : return -EINVAL;
2462 :
2463 0 : err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2464 : if (err)
2465 : untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2466 : return err;
2467 : }
2468 : EXPORT_SYMBOL(remap_pfn_range);
2469 :
2470 : /**
2471 : * vm_iomap_memory - remap memory to userspace
2472 : * @vma: user vma to map to
2473 : * @start: start of the physical memory to be mapped
2474 : * @len: size of area
2475 : *
2476 : * This is a simplified io_remap_pfn_range() for common driver use. The
2477 : * driver just needs to give us the physical memory range to be mapped,
2478 : * we'll figure out the rest from the vma information.
2479 : *
2480 : * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2481 : * whatever write-combining details or similar.
2482 : *
2483 : * Return: %0 on success, negative error code otherwise.
2484 : */
2485 0 : int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2486 : {
2487 : unsigned long vm_len, pfn, pages;
2488 :
2489 : /* Check that the physical memory area passed in looks valid */
2490 0 : if (start + len < start)
2491 : return -EINVAL;
2492 : /*
2493 : * You *really* shouldn't map things that aren't page-aligned,
2494 : * but we've historically allowed it because IO memory might
2495 : * just have smaller alignment.
2496 : */
2497 0 : len += start & ~PAGE_MASK;
2498 0 : pfn = start >> PAGE_SHIFT;
2499 0 : pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2500 0 : if (pfn + pages < pfn)
2501 : return -EINVAL;
2502 :
2503 : /* We start the mapping 'vm_pgoff' pages into the area */
2504 0 : if (vma->vm_pgoff > pages)
2505 : return -EINVAL;
2506 0 : pfn += vma->vm_pgoff;
2507 0 : pages -= vma->vm_pgoff;
2508 :
2509 : /* Can we fit all of the mapping? */
2510 0 : vm_len = vma->vm_end - vma->vm_start;
2511 0 : if (vm_len >> PAGE_SHIFT > pages)
2512 : return -EINVAL;
2513 :
2514 : /* Ok, let it rip */
2515 0 : return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2516 : }
2517 : EXPORT_SYMBOL(vm_iomap_memory);
2518 :
2519 0 : static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2520 : unsigned long addr, unsigned long end,
2521 : pte_fn_t fn, void *data, bool create,
2522 : pgtbl_mod_mask *mask)
2523 : {
2524 : pte_t *pte, *mapped_pte;
2525 0 : int err = 0;
2526 : spinlock_t *ptl;
2527 :
2528 0 : if (create) {
2529 0 : mapped_pte = pte = (mm == &init_mm) ?
2530 0 : pte_alloc_kernel_track(pmd, addr, mask) :
2531 0 : pte_alloc_map_lock(mm, pmd, addr, &ptl);
2532 0 : if (!pte)
2533 : return -ENOMEM;
2534 : } else {
2535 : mapped_pte = pte = (mm == &init_mm) ?
2536 0 : pte_offset_kernel(pmd, addr) :
2537 0 : pte_offset_map_lock(mm, pmd, addr, &ptl);
2538 : }
2539 :
2540 0 : BUG_ON(pmd_huge(*pmd));
2541 :
2542 : arch_enter_lazy_mmu_mode();
2543 :
2544 0 : if (fn) {
2545 : do {
2546 0 : if (create || !pte_none(*pte)) {
2547 0 : err = fn(pte++, addr, data);
2548 0 : if (err)
2549 : break;
2550 : }
2551 0 : } while (addr += PAGE_SIZE, addr != end);
2552 : }
2553 0 : *mask |= PGTBL_PTE_MODIFIED;
2554 :
2555 : arch_leave_lazy_mmu_mode();
2556 :
2557 0 : if (mm != &init_mm)
2558 0 : pte_unmap_unlock(mapped_pte, ptl);
2559 : return err;
2560 : }
2561 :
2562 0 : static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2563 : unsigned long addr, unsigned long end,
2564 : pte_fn_t fn, void *data, bool create,
2565 : pgtbl_mod_mask *mask)
2566 : {
2567 : pmd_t *pmd;
2568 : unsigned long next;
2569 0 : int err = 0;
2570 :
2571 0 : BUG_ON(pud_huge(*pud));
2572 :
2573 0 : if (create) {
2574 0 : pmd = pmd_alloc_track(mm, pud, addr, mask);
2575 0 : if (!pmd)
2576 : return -ENOMEM;
2577 : } else {
2578 0 : pmd = pmd_offset(pud, addr);
2579 : }
2580 : do {
2581 0 : next = pmd_addr_end(addr, end);
2582 0 : if (pmd_none(*pmd) && !create)
2583 0 : continue;
2584 0 : if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2585 : return -EINVAL;
2586 0 : if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2587 0 : if (!create)
2588 0 : continue;
2589 0 : pmd_clear_bad(pmd);
2590 : }
2591 0 : err = apply_to_pte_range(mm, pmd, addr, next,
2592 : fn, data, create, mask);
2593 0 : if (err)
2594 : break;
2595 0 : } while (pmd++, addr = next, addr != end);
2596 :
2597 : return err;
2598 : }
2599 :
2600 0 : static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2601 : unsigned long addr, unsigned long end,
2602 : pte_fn_t fn, void *data, bool create,
2603 : pgtbl_mod_mask *mask)
2604 : {
2605 : pud_t *pud;
2606 : unsigned long next;
2607 0 : int err = 0;
2608 :
2609 0 : if (create) {
2610 0 : pud = pud_alloc_track(mm, p4d, addr, mask);
2611 0 : if (!pud)
2612 : return -ENOMEM;
2613 : } else {
2614 : pud = pud_offset(p4d, addr);
2615 : }
2616 : do {
2617 0 : next = pud_addr_end(addr, end);
2618 0 : if (pud_none(*pud) && !create)
2619 0 : continue;
2620 0 : if (WARN_ON_ONCE(pud_leaf(*pud)))
2621 : return -EINVAL;
2622 0 : if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2623 0 : if (!create)
2624 0 : continue;
2625 : pud_clear_bad(pud);
2626 : }
2627 0 : err = apply_to_pmd_range(mm, pud, addr, next,
2628 : fn, data, create, mask);
2629 0 : if (err)
2630 : break;
2631 0 : } while (pud++, addr = next, addr != end);
2632 :
2633 : return err;
2634 : }
2635 :
2636 : static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2637 : unsigned long addr, unsigned long end,
2638 : pte_fn_t fn, void *data, bool create,
2639 : pgtbl_mod_mask *mask)
2640 : {
2641 : p4d_t *p4d;
2642 : unsigned long next;
2643 0 : int err = 0;
2644 :
2645 0 : if (create) {
2646 0 : p4d = p4d_alloc_track(mm, pgd, addr, mask);
2647 0 : if (!p4d)
2648 : return -ENOMEM;
2649 : } else {
2650 : p4d = p4d_offset(pgd, addr);
2651 : }
2652 : do {
2653 0 : next = p4d_addr_end(addr, end);
2654 0 : if (p4d_none(*p4d) && !create)
2655 : continue;
2656 0 : if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2657 : return -EINVAL;
2658 0 : if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2659 : if (!create)
2660 : continue;
2661 : p4d_clear_bad(p4d);
2662 : }
2663 0 : err = apply_to_pud_range(mm, p4d, addr, next,
2664 : fn, data, create, mask);
2665 : if (err)
2666 : break;
2667 : } while (p4d++, addr = next, addr != end);
2668 :
2669 : return err;
2670 : }
2671 :
2672 0 : static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2673 : unsigned long size, pte_fn_t fn,
2674 : void *data, bool create)
2675 : {
2676 : pgd_t *pgd;
2677 0 : unsigned long start = addr, next;
2678 0 : unsigned long end = addr + size;
2679 0 : pgtbl_mod_mask mask = 0;
2680 0 : int err = 0;
2681 :
2682 0 : if (WARN_ON(addr >= end))
2683 : return -EINVAL;
2684 :
2685 0 : pgd = pgd_offset(mm, addr);
2686 : do {
2687 0 : next = pgd_addr_end(addr, end);
2688 0 : if (pgd_none(*pgd) && !create)
2689 : continue;
2690 0 : if (WARN_ON_ONCE(pgd_leaf(*pgd)))
2691 : return -EINVAL;
2692 0 : if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2693 : if (!create)
2694 : continue;
2695 : pgd_clear_bad(pgd);
2696 : }
2697 0 : err = apply_to_p4d_range(mm, pgd, addr, next,
2698 : fn, data, create, &mask);
2699 0 : if (err)
2700 : break;
2701 0 : } while (pgd++, addr = next, addr != end);
2702 :
2703 : if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2704 : arch_sync_kernel_mappings(start, start + size);
2705 :
2706 : return err;
2707 : }
2708 :
2709 : /*
2710 : * Scan a region of virtual memory, filling in page tables as necessary
2711 : * and calling a provided function on each leaf page table.
2712 : */
2713 0 : int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2714 : unsigned long size, pte_fn_t fn, void *data)
2715 : {
2716 0 : return __apply_to_page_range(mm, addr, size, fn, data, true);
2717 : }
2718 : EXPORT_SYMBOL_GPL(apply_to_page_range);
2719 :
2720 : /*
2721 : * Scan a region of virtual memory, calling a provided function on
2722 : * each leaf page table where it exists.
2723 : *
2724 : * Unlike apply_to_page_range, this does _not_ fill in page tables
2725 : * where they are absent.
2726 : */
2727 0 : int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2728 : unsigned long size, pte_fn_t fn, void *data)
2729 : {
2730 0 : return __apply_to_page_range(mm, addr, size, fn, data, false);
2731 : }
2732 : EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2733 :
2734 : /*
2735 : * handle_pte_fault chooses page fault handler according to an entry which was
2736 : * read non-atomically. Before making any commitment, on those architectures
2737 : * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2738 : * parts, do_swap_page must check under lock before unmapping the pte and
2739 : * proceeding (but do_wp_page is only called after already making such a check;
2740 : * and do_anonymous_page can safely check later on).
2741 : */
2742 : static inline int pte_unmap_same(struct vm_fault *vmf)
2743 : {
2744 0 : int same = 1;
2745 : #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2746 : if (sizeof(pte_t) > sizeof(unsigned long)) {
2747 : spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
2748 : spin_lock(ptl);
2749 : same = pte_same(*vmf->pte, vmf->orig_pte);
2750 : spin_unlock(ptl);
2751 : }
2752 : #endif
2753 : pte_unmap(vmf->pte);
2754 0 : vmf->pte = NULL;
2755 : return same;
2756 : }
2757 :
2758 0 : static inline bool cow_user_page(struct page *dst, struct page *src,
2759 : struct vm_fault *vmf)
2760 : {
2761 : bool ret;
2762 : void *kaddr;
2763 : void __user *uaddr;
2764 0 : bool locked = false;
2765 0 : struct vm_area_struct *vma = vmf->vma;
2766 0 : struct mm_struct *mm = vma->vm_mm;
2767 0 : unsigned long addr = vmf->address;
2768 :
2769 0 : if (likely(src)) {
2770 0 : copy_user_highpage(dst, src, addr, vma);
2771 0 : return true;
2772 : }
2773 :
2774 : /*
2775 : * If the source page was a PFN mapping, we don't have
2776 : * a "struct page" for it. We do a best-effort copy by
2777 : * just copying from the original user address. If that
2778 : * fails, we just zero-fill it. Live with it.
2779 : */
2780 0 : kaddr = kmap_atomic(dst);
2781 0 : uaddr = (void __user *)(addr & PAGE_MASK);
2782 :
2783 : /*
2784 : * On architectures with software "accessed" bits, we would
2785 : * take a double page fault, so mark it accessed here.
2786 : */
2787 0 : if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
2788 : pte_t entry;
2789 :
2790 0 : vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2791 0 : locked = true;
2792 0 : if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2793 : /*
2794 : * Other thread has already handled the fault
2795 : * and update local tlb only
2796 : */
2797 0 : update_mmu_tlb(vma, addr, vmf->pte);
2798 0 : ret = false;
2799 0 : goto pte_unlock;
2800 : }
2801 :
2802 0 : entry = pte_mkyoung(vmf->orig_pte);
2803 0 : if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2804 : update_mmu_cache(vma, addr, vmf->pte);
2805 : }
2806 :
2807 : /*
2808 : * This really shouldn't fail, because the page is there
2809 : * in the page tables. But it might just be unreadable,
2810 : * in which case we just give up and fill the result with
2811 : * zeroes.
2812 : */
2813 0 : if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2814 0 : if (locked)
2815 : goto warn;
2816 :
2817 : /* Re-validate under PTL if the page is still mapped */
2818 0 : vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2819 0 : locked = true;
2820 0 : if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2821 : /* The PTE changed under us, update local tlb */
2822 : update_mmu_tlb(vma, addr, vmf->pte);
2823 : ret = false;
2824 : goto pte_unlock;
2825 : }
2826 :
2827 : /*
2828 : * The same page can be mapped back since last copy attempt.
2829 : * Try to copy again under PTL.
2830 : */
2831 0 : if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2832 : /*
2833 : * Give a warn in case there can be some obscure
2834 : * use-case
2835 : */
2836 : warn:
2837 0 : WARN_ON_ONCE(1);
2838 0 : clear_page(kaddr);
2839 : }
2840 : }
2841 :
2842 : ret = true;
2843 :
2844 : pte_unlock:
2845 0 : if (locked)
2846 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
2847 0 : kunmap_atomic(kaddr);
2848 0 : flush_dcache_page(dst);
2849 :
2850 0 : return ret;
2851 : }
2852 :
2853 : static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2854 : {
2855 0 : struct file *vm_file = vma->vm_file;
2856 :
2857 0 : if (vm_file)
2858 0 : return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2859 :
2860 : /*
2861 : * Special mappings (e.g. VDSO) do not have any file so fake
2862 : * a default GFP_KERNEL for them.
2863 : */
2864 : return GFP_KERNEL;
2865 : }
2866 :
2867 : /*
2868 : * Notify the address space that the page is about to become writable so that
2869 : * it can prohibit this or wait for the page to get into an appropriate state.
2870 : *
2871 : * We do this without the lock held, so that it can sleep if it needs to.
2872 : */
2873 0 : static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2874 : {
2875 : vm_fault_t ret;
2876 0 : struct page *page = vmf->page;
2877 0 : unsigned int old_flags = vmf->flags;
2878 :
2879 0 : vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2880 :
2881 0 : if (vmf->vma->vm_file &&
2882 0 : IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2883 : return VM_FAULT_SIGBUS;
2884 :
2885 0 : ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2886 : /* Restore original flags so that caller is not surprised */
2887 0 : vmf->flags = old_flags;
2888 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2889 : return ret;
2890 0 : if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2891 0 : lock_page(page);
2892 0 : if (!page->mapping) {
2893 0 : unlock_page(page);
2894 0 : return 0; /* retry */
2895 : }
2896 0 : ret |= VM_FAULT_LOCKED;
2897 : } else
2898 : VM_BUG_ON_PAGE(!PageLocked(page), page);
2899 : return ret;
2900 : }
2901 :
2902 : /*
2903 : * Handle dirtying of a page in shared file mapping on a write fault.
2904 : *
2905 : * The function expects the page to be locked and unlocks it.
2906 : */
2907 0 : static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2908 : {
2909 0 : struct vm_area_struct *vma = vmf->vma;
2910 : struct address_space *mapping;
2911 0 : struct page *page = vmf->page;
2912 : bool dirtied;
2913 0 : bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2914 :
2915 0 : dirtied = set_page_dirty(page);
2916 : VM_BUG_ON_PAGE(PageAnon(page), page);
2917 : /*
2918 : * Take a local copy of the address_space - page.mapping may be zeroed
2919 : * by truncate after unlock_page(). The address_space itself remains
2920 : * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2921 : * release semantics to prevent the compiler from undoing this copying.
2922 : */
2923 0 : mapping = page_rmapping(page);
2924 0 : unlock_page(page);
2925 :
2926 0 : if (!page_mkwrite)
2927 0 : file_update_time(vma->vm_file);
2928 :
2929 : /*
2930 : * Throttle page dirtying rate down to writeback speed.
2931 : *
2932 : * mapping may be NULL here because some device drivers do not
2933 : * set page.mapping but still dirty their pages
2934 : *
2935 : * Drop the mmap_lock before waiting on IO, if we can. The file
2936 : * is pinning the mapping, as per above.
2937 : */
2938 0 : if ((dirtied || page_mkwrite) && mapping) {
2939 : struct file *fpin;
2940 :
2941 0 : fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2942 0 : balance_dirty_pages_ratelimited(mapping);
2943 0 : if (fpin) {
2944 0 : fput(fpin);
2945 0 : return VM_FAULT_RETRY;
2946 : }
2947 : }
2948 :
2949 : return 0;
2950 : }
2951 :
2952 : /*
2953 : * Handle write page faults for pages that can be reused in the current vma
2954 : *
2955 : * This can happen either due to the mapping being with the VM_SHARED flag,
2956 : * or due to us being the last reference standing to the page. In either
2957 : * case, all we need to do here is to mark the page as writable and update
2958 : * any related book-keeping.
2959 : */
2960 0 : static inline void wp_page_reuse(struct vm_fault *vmf)
2961 : __releases(vmf->ptl)
2962 : {
2963 0 : struct vm_area_struct *vma = vmf->vma;
2964 0 : struct page *page = vmf->page;
2965 : pte_t entry;
2966 : /*
2967 : * Clear the pages cpupid information as the existing
2968 : * information potentially belongs to a now completely
2969 : * unrelated process.
2970 : */
2971 : if (page)
2972 : page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2973 :
2974 0 : flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2975 0 : entry = pte_mkyoung(vmf->orig_pte);
2976 0 : entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2977 0 : if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2978 : update_mmu_cache(vma, vmf->address, vmf->pte);
2979 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
2980 0 : count_vm_event(PGREUSE);
2981 0 : }
2982 :
2983 : /*
2984 : * Handle the case of a page which we actually need to copy to a new page.
2985 : *
2986 : * Called with mmap_lock locked and the old page referenced, but
2987 : * without the ptl held.
2988 : *
2989 : * High level logic flow:
2990 : *
2991 : * - Allocate a page, copy the content of the old page to the new one.
2992 : * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2993 : * - Take the PTL. If the pte changed, bail out and release the allocated page
2994 : * - If the pte is still the way we remember it, update the page table and all
2995 : * relevant references. This includes dropping the reference the page-table
2996 : * held to the old page, as well as updating the rmap.
2997 : * - In any case, unlock the PTL and drop the reference we took to the old page.
2998 : */
2999 0 : static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3000 : {
3001 0 : struct vm_area_struct *vma = vmf->vma;
3002 0 : struct mm_struct *mm = vma->vm_mm;
3003 0 : struct page *old_page = vmf->page;
3004 0 : struct page *new_page = NULL;
3005 : pte_t entry;
3006 0 : int page_copied = 0;
3007 : struct mmu_notifier_range range;
3008 :
3009 0 : if (unlikely(anon_vma_prepare(vma)))
3010 : goto oom;
3011 :
3012 0 : if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
3013 0 : new_page = alloc_zeroed_user_highpage_movable(vma,
3014 : vmf->address);
3015 0 : if (!new_page)
3016 : goto oom;
3017 : } else {
3018 0 : new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3019 : vmf->address);
3020 0 : if (!new_page)
3021 : goto oom;
3022 :
3023 0 : if (!cow_user_page(new_page, old_page, vmf)) {
3024 : /*
3025 : * COW failed, if the fault was solved by other,
3026 : * it's fine. If not, userspace would re-fault on
3027 : * the same address and we will handle the fault
3028 : * from the second attempt.
3029 : */
3030 0 : put_page(new_page);
3031 0 : if (old_page)
3032 0 : put_page(old_page);
3033 : return 0;
3034 : }
3035 : }
3036 :
3037 0 : if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL))
3038 : goto oom_free_new;
3039 0 : cgroup_throttle_swaprate(new_page, GFP_KERNEL);
3040 :
3041 0 : __SetPageUptodate(new_page);
3042 :
3043 0 : mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
3044 : vmf->address & PAGE_MASK,
3045 : (vmf->address & PAGE_MASK) + PAGE_SIZE);
3046 0 : mmu_notifier_invalidate_range_start(&range);
3047 :
3048 : /*
3049 : * Re-check the pte - we dropped the lock
3050 : */
3051 0 : vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3052 0 : if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
3053 0 : if (old_page) {
3054 0 : if (!PageAnon(old_page)) {
3055 0 : dec_mm_counter_fast(mm,
3056 : mm_counter_file(old_page));
3057 : inc_mm_counter_fast(mm, MM_ANONPAGES);
3058 : }
3059 : } else {
3060 : inc_mm_counter_fast(mm, MM_ANONPAGES);
3061 : }
3062 0 : flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3063 0 : entry = mk_pte(new_page, vma->vm_page_prot);
3064 : entry = pte_sw_mkyoung(entry);
3065 0 : entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3066 :
3067 : /*
3068 : * Clear the pte entry and flush it first, before updating the
3069 : * pte with the new entry, to keep TLBs on different CPUs in
3070 : * sync. This code used to set the new PTE then flush TLBs, but
3071 : * that left a window where the new PTE could be loaded into
3072 : * some TLBs while the old PTE remains in others.
3073 : */
3074 0 : ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
3075 0 : page_add_new_anon_rmap(new_page, vma, vmf->address, false);
3076 0 : lru_cache_add_inactive_or_unevictable(new_page, vma);
3077 : /*
3078 : * We call the notify macro here because, when using secondary
3079 : * mmu page tables (such as kvm shadow page tables), we want the
3080 : * new page to be mapped directly into the secondary page table.
3081 : */
3082 0 : set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
3083 : update_mmu_cache(vma, vmf->address, vmf->pte);
3084 0 : if (old_page) {
3085 : /*
3086 : * Only after switching the pte to the new page may
3087 : * we remove the mapcount here. Otherwise another
3088 : * process may come and find the rmap count decremented
3089 : * before the pte is switched to the new page, and
3090 : * "reuse" the old page writing into it while our pte
3091 : * here still points into it and can be read by other
3092 : * threads.
3093 : *
3094 : * The critical issue is to order this
3095 : * page_remove_rmap with the ptp_clear_flush above.
3096 : * Those stores are ordered by (if nothing else,)
3097 : * the barrier present in the atomic_add_negative
3098 : * in page_remove_rmap.
3099 : *
3100 : * Then the TLB flush in ptep_clear_flush ensures that
3101 : * no process can access the old page before the
3102 : * decremented mapcount is visible. And the old page
3103 : * cannot be reused until after the decremented
3104 : * mapcount is visible. So transitively, TLBs to
3105 : * old page will be flushed before it can be reused.
3106 : */
3107 0 : page_remove_rmap(old_page, vma, false);
3108 : }
3109 :
3110 : /* Free the old page.. */
3111 : new_page = old_page;
3112 : page_copied = 1;
3113 : } else {
3114 : update_mmu_tlb(vma, vmf->address, vmf->pte);
3115 : }
3116 :
3117 0 : if (new_page)
3118 0 : put_page(new_page);
3119 :
3120 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3121 : /*
3122 : * No need to double call mmu_notifier->invalidate_range() callback as
3123 : * the above ptep_clear_flush_notify() did already call it.
3124 : */
3125 0 : mmu_notifier_invalidate_range_only_end(&range);
3126 0 : if (old_page) {
3127 0 : if (page_copied)
3128 0 : free_swap_cache(old_page);
3129 0 : put_page(old_page);
3130 : }
3131 0 : return page_copied ? VM_FAULT_WRITE : 0;
3132 : oom_free_new:
3133 : put_page(new_page);
3134 : oom:
3135 0 : if (old_page)
3136 0 : put_page(old_page);
3137 : return VM_FAULT_OOM;
3138 : }
3139 :
3140 : /**
3141 : * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3142 : * writeable once the page is prepared
3143 : *
3144 : * @vmf: structure describing the fault
3145 : *
3146 : * This function handles all that is needed to finish a write page fault in a
3147 : * shared mapping due to PTE being read-only once the mapped page is prepared.
3148 : * It handles locking of PTE and modifying it.
3149 : *
3150 : * The function expects the page to be locked or other protection against
3151 : * concurrent faults / writeback (such as DAX radix tree locks).
3152 : *
3153 : * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3154 : * we acquired PTE lock.
3155 : */
3156 0 : vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
3157 : {
3158 0 : WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3159 0 : vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3160 : &vmf->ptl);
3161 : /*
3162 : * We might have raced with another page fault while we released the
3163 : * pte_offset_map_lock.
3164 : */
3165 0 : if (!pte_same(*vmf->pte, vmf->orig_pte)) {
3166 0 : update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3167 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3168 0 : return VM_FAULT_NOPAGE;
3169 : }
3170 0 : wp_page_reuse(vmf);
3171 0 : return 0;
3172 : }
3173 :
3174 : /*
3175 : * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3176 : * mapping
3177 : */
3178 0 : static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3179 : {
3180 0 : struct vm_area_struct *vma = vmf->vma;
3181 :
3182 0 : if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3183 : vm_fault_t ret;
3184 :
3185 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3186 0 : vmf->flags |= FAULT_FLAG_MKWRITE;
3187 0 : ret = vma->vm_ops->pfn_mkwrite(vmf);
3188 0 : if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3189 : return ret;
3190 0 : return finish_mkwrite_fault(vmf);
3191 : }
3192 0 : wp_page_reuse(vmf);
3193 0 : return VM_FAULT_WRITE;
3194 : }
3195 :
3196 0 : static vm_fault_t wp_page_shared(struct vm_fault *vmf)
3197 : __releases(vmf->ptl)
3198 : {
3199 0 : struct vm_area_struct *vma = vmf->vma;
3200 0 : vm_fault_t ret = VM_FAULT_WRITE;
3201 :
3202 0 : get_page(vmf->page);
3203 :
3204 0 : if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3205 : vm_fault_t tmp;
3206 :
3207 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3208 0 : tmp = do_page_mkwrite(vmf);
3209 0 : if (unlikely(!tmp || (tmp &
3210 : (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3211 0 : put_page(vmf->page);
3212 0 : return tmp;
3213 : }
3214 0 : tmp = finish_mkwrite_fault(vmf);
3215 0 : if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3216 0 : unlock_page(vmf->page);
3217 0 : put_page(vmf->page);
3218 0 : return tmp;
3219 : }
3220 : } else {
3221 0 : wp_page_reuse(vmf);
3222 0 : lock_page(vmf->page);
3223 : }
3224 0 : ret |= fault_dirty_shared_page(vmf);
3225 0 : put_page(vmf->page);
3226 :
3227 0 : return ret;
3228 : }
3229 :
3230 : /*
3231 : * This routine handles present pages, when users try to write
3232 : * to a shared page. It is done by copying the page to a new address
3233 : * and decrementing the shared-page counter for the old page.
3234 : *
3235 : * Note that this routine assumes that the protection checks have been
3236 : * done by the caller (the low-level page fault routine in most cases).
3237 : * Thus we can safely just mark it writable once we've done any necessary
3238 : * COW.
3239 : *
3240 : * We also mark the page dirty at this point even though the page will
3241 : * change only once the write actually happens. This avoids a few races,
3242 : * and potentially makes it more efficient.
3243 : *
3244 : * We enter with non-exclusive mmap_lock (to exclude vma changes,
3245 : * but allow concurrent faults), with pte both mapped and locked.
3246 : * We return with mmap_lock still held, but pte unmapped and unlocked.
3247 : */
3248 0 : static vm_fault_t do_wp_page(struct vm_fault *vmf)
3249 : __releases(vmf->ptl)
3250 : {
3251 0 : struct vm_area_struct *vma = vmf->vma;
3252 :
3253 0 : if (userfaultfd_pte_wp(vma, *vmf->pte)) {
3254 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3255 : return handle_userfault(vmf, VM_UFFD_WP);
3256 : }
3257 :
3258 : /*
3259 : * Userfaultfd write-protect can defer flushes. Ensure the TLB
3260 : * is flushed in this case before copying.
3261 : */
3262 0 : if (unlikely(userfaultfd_wp(vmf->vma) &&
3263 : mm_tlb_flush_pending(vmf->vma->vm_mm)))
3264 : flush_tlb_page(vmf->vma, vmf->address);
3265 :
3266 0 : vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3267 0 : if (!vmf->page) {
3268 : /*
3269 : * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3270 : * VM_PFNMAP VMA.
3271 : *
3272 : * We should not cow pages in a shared writeable mapping.
3273 : * Just mark the pages writable and/or call ops->pfn_mkwrite.
3274 : */
3275 0 : if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3276 : (VM_WRITE|VM_SHARED))
3277 0 : return wp_pfn_shared(vmf);
3278 :
3279 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3280 0 : return wp_page_copy(vmf);
3281 : }
3282 :
3283 : /*
3284 : * Take out anonymous pages first, anonymous shared vmas are
3285 : * not dirty accountable.
3286 : */
3287 0 : if (PageAnon(vmf->page)) {
3288 0 : struct page *page = vmf->page;
3289 :
3290 : /*
3291 : * We have to verify under page lock: these early checks are
3292 : * just an optimization to avoid locking the page and freeing
3293 : * the swapcache if there is little hope that we can reuse.
3294 : *
3295 : * PageKsm() doesn't necessarily raise the page refcount.
3296 : */
3297 0 : if (PageKsm(page) || page_count(page) > 3)
3298 : goto copy;
3299 0 : if (!PageLRU(page))
3300 : /*
3301 : * Note: We cannot easily detect+handle references from
3302 : * remote LRU pagevecs or references to PageLRU() pages.
3303 : */
3304 0 : lru_add_drain();
3305 0 : if (page_count(page) > 1 + PageSwapCache(page))
3306 : goto copy;
3307 0 : if (!trylock_page(page))
3308 : goto copy;
3309 0 : if (PageSwapCache(page))
3310 0 : try_to_free_swap(page);
3311 0 : if (PageKsm(page) || page_count(page) != 1) {
3312 0 : unlock_page(page);
3313 0 : goto copy;
3314 : }
3315 : /*
3316 : * Ok, we've got the only page reference from our mapping
3317 : * and the page is locked, it's dark out, and we're wearing
3318 : * sunglasses. Hit it.
3319 : */
3320 0 : unlock_page(page);
3321 0 : wp_page_reuse(vmf);
3322 0 : return VM_FAULT_WRITE;
3323 0 : } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3324 : (VM_WRITE|VM_SHARED))) {
3325 0 : return wp_page_shared(vmf);
3326 : }
3327 : copy:
3328 : /*
3329 : * Ok, we need to copy. Oh, well..
3330 : */
3331 0 : get_page(vmf->page);
3332 :
3333 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3334 0 : return wp_page_copy(vmf);
3335 : }
3336 :
3337 : static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3338 : unsigned long start_addr, unsigned long end_addr,
3339 : struct zap_details *details)
3340 : {
3341 0 : zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3342 : }
3343 :
3344 0 : static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3345 : pgoff_t first_index,
3346 : pgoff_t last_index,
3347 : struct zap_details *details)
3348 : {
3349 : struct vm_area_struct *vma;
3350 : pgoff_t vba, vea, zba, zea;
3351 :
3352 0 : vma_interval_tree_foreach(vma, root, first_index, last_index) {
3353 0 : vba = vma->vm_pgoff;
3354 0 : vea = vba + vma_pages(vma) - 1;
3355 0 : zba = max(first_index, vba);
3356 0 : zea = min(last_index, vea);
3357 :
3358 0 : unmap_mapping_range_vma(vma,
3359 0 : ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3360 0 : ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3361 : details);
3362 : }
3363 0 : }
3364 :
3365 : /**
3366 : * unmap_mapping_folio() - Unmap single folio from processes.
3367 : * @folio: The locked folio to be unmapped.
3368 : *
3369 : * Unmap this folio from any userspace process which still has it mmaped.
3370 : * Typically, for efficiency, the range of nearby pages has already been
3371 : * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3372 : * truncation or invalidation holds the lock on a folio, it may find that
3373 : * the page has been remapped again: and then uses unmap_mapping_folio()
3374 : * to unmap it finally.
3375 : */
3376 0 : void unmap_mapping_folio(struct folio *folio)
3377 : {
3378 0 : struct address_space *mapping = folio->mapping;
3379 0 : struct zap_details details = { };
3380 : pgoff_t first_index;
3381 : pgoff_t last_index;
3382 :
3383 : VM_BUG_ON(!folio_test_locked(folio));
3384 :
3385 0 : first_index = folio->index;
3386 0 : last_index = folio->index + folio_nr_pages(folio) - 1;
3387 :
3388 : details.even_cows = false;
3389 0 : details.single_folio = folio;
3390 :
3391 0 : i_mmap_lock_read(mapping);
3392 0 : if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3393 0 : unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3394 : last_index, &details);
3395 0 : i_mmap_unlock_read(mapping);
3396 0 : }
3397 :
3398 : /**
3399 : * unmap_mapping_pages() - Unmap pages from processes.
3400 : * @mapping: The address space containing pages to be unmapped.
3401 : * @start: Index of first page to be unmapped.
3402 : * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3403 : * @even_cows: Whether to unmap even private COWed pages.
3404 : *
3405 : * Unmap the pages in this address space from any userspace process which
3406 : * has them mmaped. Generally, you want to remove COWed pages as well when
3407 : * a file is being truncated, but not when invalidating pages from the page
3408 : * cache.
3409 : */
3410 0 : void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3411 : pgoff_t nr, bool even_cows)
3412 : {
3413 0 : struct zap_details details = { };
3414 0 : pgoff_t first_index = start;
3415 0 : pgoff_t last_index = start + nr - 1;
3416 :
3417 0 : details.even_cows = even_cows;
3418 0 : if (last_index < first_index)
3419 0 : last_index = ULONG_MAX;
3420 :
3421 0 : i_mmap_lock_read(mapping);
3422 0 : if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3423 0 : unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3424 : last_index, &details);
3425 0 : i_mmap_unlock_read(mapping);
3426 0 : }
3427 : EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3428 :
3429 : /**
3430 : * unmap_mapping_range - unmap the portion of all mmaps in the specified
3431 : * address_space corresponding to the specified byte range in the underlying
3432 : * file.
3433 : *
3434 : * @mapping: the address space containing mmaps to be unmapped.
3435 : * @holebegin: byte in first page to unmap, relative to the start of
3436 : * the underlying file. This will be rounded down to a PAGE_SIZE
3437 : * boundary. Note that this is different from truncate_pagecache(), which
3438 : * must keep the partial page. In contrast, we must get rid of
3439 : * partial pages.
3440 : * @holelen: size of prospective hole in bytes. This will be rounded
3441 : * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3442 : * end of the file.
3443 : * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3444 : * but 0 when invalidating pagecache, don't throw away private data.
3445 : */
3446 0 : void unmap_mapping_range(struct address_space *mapping,
3447 : loff_t const holebegin, loff_t const holelen, int even_cows)
3448 : {
3449 0 : pgoff_t hba = holebegin >> PAGE_SHIFT;
3450 0 : pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3451 :
3452 : /* Check for overflow. */
3453 : if (sizeof(holelen) > sizeof(hlen)) {
3454 : long long holeend =
3455 : (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3456 : if (holeend & ~(long long)ULONG_MAX)
3457 : hlen = ULONG_MAX - hba + 1;
3458 : }
3459 :
3460 0 : unmap_mapping_pages(mapping, hba, hlen, even_cows);
3461 0 : }
3462 : EXPORT_SYMBOL(unmap_mapping_range);
3463 :
3464 : /*
3465 : * Restore a potential device exclusive pte to a working pte entry
3466 : */
3467 : static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3468 : {
3469 : struct page *page = vmf->page;
3470 : struct vm_area_struct *vma = vmf->vma;
3471 : struct mmu_notifier_range range;
3472 :
3473 : if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags))
3474 : return VM_FAULT_RETRY;
3475 : mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
3476 : vma->vm_mm, vmf->address & PAGE_MASK,
3477 : (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3478 : mmu_notifier_invalidate_range_start(&range);
3479 :
3480 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3481 : &vmf->ptl);
3482 : if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3483 : restore_exclusive_pte(vma, page, vmf->address, vmf->pte);
3484 :
3485 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3486 : unlock_page(page);
3487 :
3488 : mmu_notifier_invalidate_range_end(&range);
3489 : return 0;
3490 : }
3491 :
3492 0 : static inline bool should_try_to_free_swap(struct page *page,
3493 : struct vm_area_struct *vma,
3494 : unsigned int fault_flags)
3495 : {
3496 0 : if (!PageSwapCache(page))
3497 : return false;
3498 0 : if (mem_cgroup_swap_full(page) || (vma->vm_flags & VM_LOCKED) ||
3499 0 : PageMlocked(page))
3500 : return true;
3501 : /*
3502 : * If we want to map a page that's in the swapcache writable, we
3503 : * have to detect via the refcount if we're really the exclusive
3504 : * user. Try freeing the swapcache to get rid of the swapcache
3505 : * reference only in case it's likely that we'll be the exlusive user.
3506 : */
3507 0 : return (fault_flags & FAULT_FLAG_WRITE) && !PageKsm(page) &&
3508 0 : page_count(page) == 2;
3509 : }
3510 :
3511 : /*
3512 : * We enter with non-exclusive mmap_lock (to exclude vma changes,
3513 : * but allow concurrent faults), and pte mapped but not yet locked.
3514 : * We return with pte unmapped and unlocked.
3515 : *
3516 : * We return with the mmap_lock locked or unlocked in the same cases
3517 : * as does filemap_fault().
3518 : */
3519 0 : vm_fault_t do_swap_page(struct vm_fault *vmf)
3520 : {
3521 0 : struct vm_area_struct *vma = vmf->vma;
3522 0 : struct page *page = NULL, *swapcache;
3523 0 : struct swap_info_struct *si = NULL;
3524 : swp_entry_t entry;
3525 : pte_t pte;
3526 : int locked;
3527 0 : int exclusive = 0;
3528 0 : vm_fault_t ret = 0;
3529 0 : void *shadow = NULL;
3530 :
3531 0 : if (!pte_unmap_same(vmf))
3532 : goto out;
3533 :
3534 0 : entry = pte_to_swp_entry(vmf->orig_pte);
3535 0 : if (unlikely(non_swap_entry(entry))) {
3536 0 : if (is_migration_entry(entry)) {
3537 0 : migration_entry_wait(vma->vm_mm, vmf->pmd,
3538 : vmf->address);
3539 0 : } else if (is_device_exclusive_entry(entry)) {
3540 : vmf->page = pfn_swap_entry_to_page(entry);
3541 : ret = remove_device_exclusive_entry(vmf);
3542 0 : } else if (is_device_private_entry(entry)) {
3543 : vmf->page = pfn_swap_entry_to_page(entry);
3544 : ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3545 0 : } else if (is_hwpoison_entry(entry)) {
3546 : ret = VM_FAULT_HWPOISON;
3547 : } else {
3548 0 : print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3549 0 : ret = VM_FAULT_SIGBUS;
3550 : }
3551 : goto out;
3552 : }
3553 :
3554 : /* Prevent swapoff from happening to us. */
3555 0 : si = get_swap_device(entry);
3556 0 : if (unlikely(!si))
3557 : goto out;
3558 :
3559 0 : page = lookup_swap_cache(entry, vma, vmf->address);
3560 0 : swapcache = page;
3561 :
3562 0 : if (!page) {
3563 0 : if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3564 0 : __swap_count(entry) == 1) {
3565 : /* skip swapcache */
3566 0 : page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3567 : vmf->address);
3568 0 : if (page) {
3569 0 : __SetPageLocked(page);
3570 0 : __SetPageSwapBacked(page);
3571 :
3572 0 : if (mem_cgroup_swapin_charge_page(page,
3573 : vma->vm_mm, GFP_KERNEL, entry)) {
3574 : ret = VM_FAULT_OOM;
3575 : goto out_page;
3576 : }
3577 0 : mem_cgroup_swapin_uncharge_swap(entry);
3578 :
3579 0 : shadow = get_shadow_from_swap_cache(entry);
3580 0 : if (shadow)
3581 0 : workingset_refault(page_folio(page),
3582 : shadow);
3583 :
3584 0 : lru_cache_add(page);
3585 :
3586 : /* To provide entry to swap_readpage() */
3587 0 : set_page_private(page, entry.val);
3588 0 : swap_readpage(page, true);
3589 0 : set_page_private(page, 0);
3590 : }
3591 : } else {
3592 0 : page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3593 : vmf);
3594 0 : swapcache = page;
3595 : }
3596 :
3597 0 : if (!page) {
3598 : /*
3599 : * Back out if somebody else faulted in this pte
3600 : * while we released the pte lock.
3601 : */
3602 0 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3603 : vmf->address, &vmf->ptl);
3604 0 : if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3605 0 : ret = VM_FAULT_OOM;
3606 : goto unlock;
3607 : }
3608 :
3609 : /* Had to read the page from swap area: Major fault */
3610 0 : ret = VM_FAULT_MAJOR;
3611 0 : count_vm_event(PGMAJFAULT);
3612 0 : count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3613 : } else if (PageHWPoison(page)) {
3614 : /*
3615 : * hwpoisoned dirty swapcache pages are kept for killing
3616 : * owner processes (which may be unknown at hwpoison time)
3617 : */
3618 : ret = VM_FAULT_HWPOISON;
3619 : goto out_release;
3620 : }
3621 :
3622 0 : locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
3623 :
3624 0 : if (!locked) {
3625 0 : ret |= VM_FAULT_RETRY;
3626 0 : goto out_release;
3627 : }
3628 :
3629 0 : if (swapcache) {
3630 : /*
3631 : * Make sure try_to_free_swap or swapoff did not release the
3632 : * swapcache from under us. The page pin, and pte_same test
3633 : * below, are not enough to exclude that. Even if it is still
3634 : * swapcache, we need to check that the page's swap has not
3635 : * changed.
3636 : */
3637 0 : if (unlikely(!PageSwapCache(page) ||
3638 : page_private(page) != entry.val))
3639 : goto out_page;
3640 :
3641 : /*
3642 : * KSM sometimes has to copy on read faults, for example, if
3643 : * page->index of !PageKSM() pages would be nonlinear inside the
3644 : * anon VMA -- PageKSM() is lost on actual swapout.
3645 : */
3646 0 : page = ksm_might_need_to_copy(page, vma, vmf->address);
3647 0 : if (unlikely(!page)) {
3648 : ret = VM_FAULT_OOM;
3649 : page = swapcache;
3650 : goto out_page;
3651 : }
3652 :
3653 : /*
3654 : * If we want to map a page that's in the swapcache writable, we
3655 : * have to detect via the refcount if we're really the exclusive
3656 : * owner. Try removing the extra reference from the local LRU
3657 : * pagevecs if required.
3658 : */
3659 0 : if ((vmf->flags & FAULT_FLAG_WRITE) && page == swapcache &&
3660 0 : !PageKsm(page) && !PageLRU(page))
3661 0 : lru_add_drain();
3662 : }
3663 :
3664 0 : cgroup_throttle_swaprate(page, GFP_KERNEL);
3665 :
3666 : /*
3667 : * Back out if somebody else already faulted in this pte.
3668 : */
3669 0 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3670 : &vmf->ptl);
3671 0 : if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3672 : goto out_nomap;
3673 :
3674 0 : if (unlikely(!PageUptodate(page))) {
3675 : ret = VM_FAULT_SIGBUS;
3676 : goto out_nomap;
3677 : }
3678 :
3679 : /*
3680 : * Remove the swap entry and conditionally try to free up the swapcache.
3681 : * We're already holding a reference on the page but haven't mapped it
3682 : * yet.
3683 : */
3684 0 : swap_free(entry);
3685 0 : if (should_try_to_free_swap(page, vma, vmf->flags))
3686 0 : try_to_free_swap(page);
3687 :
3688 0 : inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3689 0 : dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3690 0 : pte = mk_pte(page, vma->vm_page_prot);
3691 :
3692 : /*
3693 : * Same logic as in do_wp_page(); however, optimize for fresh pages
3694 : * that are certainly not shared because we just allocated them without
3695 : * exposing them to the swapcache.
3696 : */
3697 0 : if ((vmf->flags & FAULT_FLAG_WRITE) && !PageKsm(page) &&
3698 0 : (page != swapcache || page_count(page) == 1)) {
3699 0 : pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3700 0 : vmf->flags &= ~FAULT_FLAG_WRITE;
3701 0 : ret |= VM_FAULT_WRITE;
3702 0 : exclusive = RMAP_EXCLUSIVE;
3703 : }
3704 0 : flush_icache_page(vma, page);
3705 0 : if (pte_swp_soft_dirty(vmf->orig_pte))
3706 : pte = pte_mksoft_dirty(pte);
3707 : if (pte_swp_uffd_wp(vmf->orig_pte)) {
3708 : pte = pte_mkuffd_wp(pte);
3709 : pte = pte_wrprotect(pte);
3710 : }
3711 0 : vmf->orig_pte = pte;
3712 :
3713 : /* ksm created a completely new copy */
3714 0 : if (unlikely(page != swapcache && swapcache)) {
3715 0 : page_add_new_anon_rmap(page, vma, vmf->address, false);
3716 0 : lru_cache_add_inactive_or_unevictable(page, vma);
3717 : } else {
3718 0 : do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3719 : }
3720 :
3721 0 : set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3722 0 : arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3723 :
3724 0 : unlock_page(page);
3725 0 : if (page != swapcache && swapcache) {
3726 : /*
3727 : * Hold the lock to avoid the swap entry to be reused
3728 : * until we take the PT lock for the pte_same() check
3729 : * (to avoid false positives from pte_same). For
3730 : * further safety release the lock after the swap_free
3731 : * so that the swap count won't change under a
3732 : * parallel locked swapcache.
3733 : */
3734 0 : unlock_page(swapcache);
3735 0 : put_page(swapcache);
3736 : }
3737 :
3738 0 : if (vmf->flags & FAULT_FLAG_WRITE) {
3739 0 : ret |= do_wp_page(vmf);
3740 0 : if (ret & VM_FAULT_ERROR)
3741 0 : ret &= VM_FAULT_ERROR;
3742 : goto out;
3743 : }
3744 :
3745 : /* No need to invalidate - it was non-present before */
3746 : update_mmu_cache(vma, vmf->address, vmf->pte);
3747 : unlock:
3748 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3749 : out:
3750 0 : if (si)
3751 : put_swap_device(si);
3752 : return ret;
3753 : out_nomap:
3754 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3755 : out_page:
3756 0 : unlock_page(page);
3757 : out_release:
3758 0 : put_page(page);
3759 0 : if (page != swapcache && swapcache) {
3760 0 : unlock_page(swapcache);
3761 0 : put_page(swapcache);
3762 : }
3763 0 : if (si)
3764 : put_swap_device(si);
3765 : return ret;
3766 : }
3767 :
3768 : /*
3769 : * We enter with non-exclusive mmap_lock (to exclude vma changes,
3770 : * but allow concurrent faults), and pte mapped but not yet locked.
3771 : * We return with mmap_lock still held, but pte unmapped and unlocked.
3772 : */
3773 0 : static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
3774 : {
3775 0 : struct vm_area_struct *vma = vmf->vma;
3776 : struct page *page;
3777 0 : vm_fault_t ret = 0;
3778 : pte_t entry;
3779 :
3780 : /* File mapping without ->vm_ops ? */
3781 0 : if (vma->vm_flags & VM_SHARED)
3782 : return VM_FAULT_SIGBUS;
3783 :
3784 : /*
3785 : * Use pte_alloc() instead of pte_alloc_map(). We can't run
3786 : * pte_offset_map() on pmds where a huge pmd might be created
3787 : * from a different thread.
3788 : *
3789 : * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
3790 : * parallel threads are excluded by other means.
3791 : *
3792 : * Here we only have mmap_read_lock(mm).
3793 : */
3794 0 : if (pte_alloc(vma->vm_mm, vmf->pmd))
3795 : return VM_FAULT_OOM;
3796 :
3797 : /* See comment in handle_pte_fault() */
3798 0 : if (unlikely(pmd_trans_unstable(vmf->pmd)))
3799 : return 0;
3800 :
3801 : /* Use the zero-page for reads */
3802 0 : if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3803 : !mm_forbids_zeropage(vma->vm_mm)) {
3804 0 : entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3805 : vma->vm_page_prot));
3806 0 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3807 : vmf->address, &vmf->ptl);
3808 0 : if (!pte_none(*vmf->pte)) {
3809 : update_mmu_tlb(vma, vmf->address, vmf->pte);
3810 : goto unlock;
3811 : }
3812 0 : ret = check_stable_address_space(vma->vm_mm);
3813 0 : if (ret)
3814 : goto unlock;
3815 : /* Deliver the page fault to userland, check inside PT lock */
3816 : if (userfaultfd_missing(vma)) {
3817 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3818 : return handle_userfault(vmf, VM_UFFD_MISSING);
3819 : }
3820 : goto setpte;
3821 : }
3822 :
3823 : /* Allocate our own private page. */
3824 0 : if (unlikely(anon_vma_prepare(vma)))
3825 : goto oom;
3826 0 : page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3827 0 : if (!page)
3828 : goto oom;
3829 :
3830 0 : if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
3831 : goto oom_free_page;
3832 0 : cgroup_throttle_swaprate(page, GFP_KERNEL);
3833 :
3834 : /*
3835 : * The memory barrier inside __SetPageUptodate makes sure that
3836 : * preceding stores to the page contents become visible before
3837 : * the set_pte_at() write.
3838 : */
3839 0 : __SetPageUptodate(page);
3840 :
3841 0 : entry = mk_pte(page, vma->vm_page_prot);
3842 : entry = pte_sw_mkyoung(entry);
3843 0 : if (vma->vm_flags & VM_WRITE)
3844 0 : entry = pte_mkwrite(pte_mkdirty(entry));
3845 :
3846 0 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3847 : &vmf->ptl);
3848 0 : if (!pte_none(*vmf->pte)) {
3849 : update_mmu_cache(vma, vmf->address, vmf->pte);
3850 : goto release;
3851 : }
3852 :
3853 0 : ret = check_stable_address_space(vma->vm_mm);
3854 0 : if (ret)
3855 : goto release;
3856 :
3857 : /* Deliver the page fault to userland, check inside PT lock */
3858 0 : if (userfaultfd_missing(vma)) {
3859 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3860 : put_page(page);
3861 : return handle_userfault(vmf, VM_UFFD_MISSING);
3862 : }
3863 :
3864 0 : inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3865 0 : page_add_new_anon_rmap(page, vma, vmf->address, false);
3866 0 : lru_cache_add_inactive_or_unevictable(page, vma);
3867 : setpte:
3868 0 : set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3869 :
3870 : /* No need to invalidate - it was non-present before */
3871 : update_mmu_cache(vma, vmf->address, vmf->pte);
3872 : unlock:
3873 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
3874 0 : return ret;
3875 : release:
3876 0 : put_page(page);
3877 0 : goto unlock;
3878 : oom_free_page:
3879 : put_page(page);
3880 : oom:
3881 : return VM_FAULT_OOM;
3882 : }
3883 :
3884 : /*
3885 : * The mmap_lock must have been held on entry, and may have been
3886 : * released depending on flags and vma->vm_ops->fault() return value.
3887 : * See filemap_fault() and __lock_page_retry().
3888 : */
3889 0 : static vm_fault_t __do_fault(struct vm_fault *vmf)
3890 : {
3891 0 : struct vm_area_struct *vma = vmf->vma;
3892 : vm_fault_t ret;
3893 :
3894 : /*
3895 : * Preallocate pte before we take page_lock because this might lead to
3896 : * deadlocks for memcg reclaim which waits for pages under writeback:
3897 : * lock_page(A)
3898 : * SetPageWriteback(A)
3899 : * unlock_page(A)
3900 : * lock_page(B)
3901 : * lock_page(B)
3902 : * pte_alloc_one
3903 : * shrink_page_list
3904 : * wait_on_page_writeback(A)
3905 : * SetPageWriteback(B)
3906 : * unlock_page(B)
3907 : * # flush A, B to clear the writeback
3908 : */
3909 0 : if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3910 0 : vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3911 0 : if (!vmf->prealloc_pte)
3912 : return VM_FAULT_OOM;
3913 : }
3914 :
3915 0 : ret = vma->vm_ops->fault(vmf);
3916 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3917 : VM_FAULT_DONE_COW)))
3918 : return ret;
3919 :
3920 0 : if (unlikely(PageHWPoison(vmf->page))) {
3921 : struct page *page = vmf->page;
3922 : vm_fault_t poisonret = VM_FAULT_HWPOISON;
3923 : if (ret & VM_FAULT_LOCKED) {
3924 : if (page_mapped(page))
3925 : unmap_mapping_pages(page_mapping(page),
3926 : page->index, 1, false);
3927 : /* Retry if a clean page was removed from the cache. */
3928 : if (invalidate_inode_page(page))
3929 : poisonret = VM_FAULT_NOPAGE;
3930 : unlock_page(page);
3931 : }
3932 : put_page(page);
3933 : vmf->page = NULL;
3934 : return poisonret;
3935 : }
3936 :
3937 0 : if (unlikely(!(ret & VM_FAULT_LOCKED)))
3938 0 : lock_page(vmf->page);
3939 : else
3940 : VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3941 :
3942 : return ret;
3943 : }
3944 :
3945 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3946 : static void deposit_prealloc_pte(struct vm_fault *vmf)
3947 : {
3948 : struct vm_area_struct *vma = vmf->vma;
3949 :
3950 : pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3951 : /*
3952 : * We are going to consume the prealloc table,
3953 : * count that as nr_ptes.
3954 : */
3955 : mm_inc_nr_ptes(vma->vm_mm);
3956 : vmf->prealloc_pte = NULL;
3957 : }
3958 :
3959 : vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3960 : {
3961 : struct vm_area_struct *vma = vmf->vma;
3962 : bool write = vmf->flags & FAULT_FLAG_WRITE;
3963 : unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3964 : pmd_t entry;
3965 : int i;
3966 : vm_fault_t ret = VM_FAULT_FALLBACK;
3967 :
3968 : if (!transhuge_vma_suitable(vma, haddr))
3969 : return ret;
3970 :
3971 : page = compound_head(page);
3972 : if (compound_order(page) != HPAGE_PMD_ORDER)
3973 : return ret;
3974 :
3975 : /*
3976 : * Just backoff if any subpage of a THP is corrupted otherwise
3977 : * the corrupted page may mapped by PMD silently to escape the
3978 : * check. This kind of THP just can be PTE mapped. Access to
3979 : * the corrupted subpage should trigger SIGBUS as expected.
3980 : */
3981 : if (unlikely(PageHasHWPoisoned(page)))
3982 : return ret;
3983 :
3984 : /*
3985 : * Archs like ppc64 need additional space to store information
3986 : * related to pte entry. Use the preallocated table for that.
3987 : */
3988 : if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3989 : vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3990 : if (!vmf->prealloc_pte)
3991 : return VM_FAULT_OOM;
3992 : }
3993 :
3994 : vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3995 : if (unlikely(!pmd_none(*vmf->pmd)))
3996 : goto out;
3997 :
3998 : for (i = 0; i < HPAGE_PMD_NR; i++)
3999 : flush_icache_page(vma, page + i);
4000 :
4001 : entry = mk_huge_pmd(page, vma->vm_page_prot);
4002 : if (write)
4003 : entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
4004 :
4005 : add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
4006 : page_add_file_rmap(page, vma, true);
4007 :
4008 : /*
4009 : * deposit and withdraw with pmd lock held
4010 : */
4011 : if (arch_needs_pgtable_deposit())
4012 : deposit_prealloc_pte(vmf);
4013 :
4014 : set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
4015 :
4016 : update_mmu_cache_pmd(vma, haddr, vmf->pmd);
4017 :
4018 : /* fault is handled */
4019 : ret = 0;
4020 : count_vm_event(THP_FILE_MAPPED);
4021 : out:
4022 : spin_unlock(vmf->ptl);
4023 : return ret;
4024 : }
4025 : #else
4026 0 : vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4027 : {
4028 0 : return VM_FAULT_FALLBACK;
4029 : }
4030 : #endif
4031 :
4032 0 : void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
4033 : {
4034 0 : struct vm_area_struct *vma = vmf->vma;
4035 0 : bool write = vmf->flags & FAULT_FLAG_WRITE;
4036 0 : bool prefault = vmf->address != addr;
4037 : pte_t entry;
4038 :
4039 0 : flush_icache_page(vma, page);
4040 0 : entry = mk_pte(page, vma->vm_page_prot);
4041 :
4042 : if (prefault && arch_wants_old_prefaulted_pte())
4043 : entry = pte_mkold(entry);
4044 : else
4045 : entry = pte_sw_mkyoung(entry);
4046 :
4047 0 : if (write)
4048 0 : entry = maybe_mkwrite(pte_mkdirty(entry), vma);
4049 : /* copy-on-write page */
4050 0 : if (write && !(vma->vm_flags & VM_SHARED)) {
4051 0 : inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
4052 0 : page_add_new_anon_rmap(page, vma, addr, false);
4053 0 : lru_cache_add_inactive_or_unevictable(page, vma);
4054 : } else {
4055 0 : inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
4056 0 : page_add_file_rmap(page, vma, false);
4057 : }
4058 0 : set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
4059 0 : }
4060 :
4061 : /**
4062 : * finish_fault - finish page fault once we have prepared the page to fault
4063 : *
4064 : * @vmf: structure describing the fault
4065 : *
4066 : * This function handles all that is needed to finish a page fault once the
4067 : * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
4068 : * given page, adds reverse page mapping, handles memcg charges and LRU
4069 : * addition.
4070 : *
4071 : * The function expects the page to be locked and on success it consumes a
4072 : * reference of a page being mapped (for the PTE which maps it).
4073 : *
4074 : * Return: %0 on success, %VM_FAULT_ code in case of error.
4075 : */
4076 0 : vm_fault_t finish_fault(struct vm_fault *vmf)
4077 : {
4078 0 : struct vm_area_struct *vma = vmf->vma;
4079 : struct page *page;
4080 : vm_fault_t ret;
4081 :
4082 : /* Did we COW the page? */
4083 0 : if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
4084 0 : page = vmf->cow_page;
4085 : else
4086 0 : page = vmf->page;
4087 :
4088 : /*
4089 : * check even for read faults because we might have lost our CoWed
4090 : * page
4091 : */
4092 0 : if (!(vma->vm_flags & VM_SHARED)) {
4093 0 : ret = check_stable_address_space(vma->vm_mm);
4094 0 : if (ret)
4095 : return ret;
4096 : }
4097 :
4098 0 : if (pmd_none(*vmf->pmd)) {
4099 0 : if (PageTransCompound(page)) {
4100 : ret = do_set_pmd(vmf, page);
4101 : if (ret != VM_FAULT_FALLBACK)
4102 : return ret;
4103 : }
4104 :
4105 0 : if (vmf->prealloc_pte)
4106 0 : pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
4107 0 : else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
4108 : return VM_FAULT_OOM;
4109 : }
4110 :
4111 : /* See comment in handle_pte_fault() */
4112 0 : if (pmd_devmap_trans_unstable(vmf->pmd))
4113 : return 0;
4114 :
4115 0 : vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4116 : vmf->address, &vmf->ptl);
4117 0 : ret = 0;
4118 : /* Re-check under ptl */
4119 0 : if (likely(pte_none(*vmf->pte)))
4120 0 : do_set_pte(vmf, page, vmf->address);
4121 : else
4122 : ret = VM_FAULT_NOPAGE;
4123 :
4124 0 : update_mmu_tlb(vma, vmf->address, vmf->pte);
4125 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4126 0 : return ret;
4127 : }
4128 :
4129 : static unsigned long fault_around_bytes __read_mostly =
4130 : rounddown_pow_of_two(65536);
4131 :
4132 : #ifdef CONFIG_DEBUG_FS
4133 : static int fault_around_bytes_get(void *data, u64 *val)
4134 : {
4135 : *val = fault_around_bytes;
4136 : return 0;
4137 : }
4138 :
4139 : /*
4140 : * fault_around_bytes must be rounded down to the nearest page order as it's
4141 : * what do_fault_around() expects to see.
4142 : */
4143 : static int fault_around_bytes_set(void *data, u64 val)
4144 : {
4145 : if (val / PAGE_SIZE > PTRS_PER_PTE)
4146 : return -EINVAL;
4147 : if (val > PAGE_SIZE)
4148 : fault_around_bytes = rounddown_pow_of_two(val);
4149 : else
4150 : fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
4151 : return 0;
4152 : }
4153 : DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
4154 : fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
4155 :
4156 : static int __init fault_around_debugfs(void)
4157 : {
4158 : debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
4159 : &fault_around_bytes_fops);
4160 : return 0;
4161 : }
4162 : late_initcall(fault_around_debugfs);
4163 : #endif
4164 :
4165 : /*
4166 : * do_fault_around() tries to map few pages around the fault address. The hope
4167 : * is that the pages will be needed soon and this will lower the number of
4168 : * faults to handle.
4169 : *
4170 : * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
4171 : * not ready to be mapped: not up-to-date, locked, etc.
4172 : *
4173 : * This function is called with the page table lock taken. In the split ptlock
4174 : * case the page table lock only protects only those entries which belong to
4175 : * the page table corresponding to the fault address.
4176 : *
4177 : * This function doesn't cross the VMA boundaries, in order to call map_pages()
4178 : * only once.
4179 : *
4180 : * fault_around_bytes defines how many bytes we'll try to map.
4181 : * do_fault_around() expects it to be set to a power of two less than or equal
4182 : * to PTRS_PER_PTE.
4183 : *
4184 : * The virtual address of the area that we map is naturally aligned to
4185 : * fault_around_bytes rounded down to the machine page size
4186 : * (and therefore to page order). This way it's easier to guarantee
4187 : * that we don't cross page table boundaries.
4188 : */
4189 0 : static vm_fault_t do_fault_around(struct vm_fault *vmf)
4190 : {
4191 0 : unsigned long address = vmf->address, nr_pages, mask;
4192 0 : pgoff_t start_pgoff = vmf->pgoff;
4193 : pgoff_t end_pgoff;
4194 : int off;
4195 :
4196 0 : nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
4197 0 : mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
4198 :
4199 0 : address = max(address & mask, vmf->vma->vm_start);
4200 0 : off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
4201 0 : start_pgoff -= off;
4202 :
4203 : /*
4204 : * end_pgoff is either the end of the page table, the end of
4205 : * the vma or nr_pages from start_pgoff, depending what is nearest.
4206 : */
4207 0 : end_pgoff = start_pgoff -
4208 0 : ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
4209 : PTRS_PER_PTE - 1;
4210 0 : end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
4211 : start_pgoff + nr_pages - 1);
4212 :
4213 0 : if (pmd_none(*vmf->pmd)) {
4214 0 : vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
4215 0 : if (!vmf->prealloc_pte)
4216 : return VM_FAULT_OOM;
4217 : }
4218 :
4219 0 : return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
4220 : }
4221 :
4222 0 : static vm_fault_t do_read_fault(struct vm_fault *vmf)
4223 : {
4224 0 : struct vm_area_struct *vma = vmf->vma;
4225 0 : vm_fault_t ret = 0;
4226 :
4227 : /*
4228 : * Let's call ->map_pages() first and use ->fault() as fallback
4229 : * if page by the offset is not ready to be mapped (cold cache or
4230 : * something).
4231 : */
4232 0 : if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
4233 0 : if (likely(!userfaultfd_minor(vmf->vma))) {
4234 0 : ret = do_fault_around(vmf);
4235 0 : if (ret)
4236 : return ret;
4237 : }
4238 : }
4239 :
4240 0 : ret = __do_fault(vmf);
4241 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4242 : return ret;
4243 :
4244 0 : ret |= finish_fault(vmf);
4245 0 : unlock_page(vmf->page);
4246 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4247 0 : put_page(vmf->page);
4248 : return ret;
4249 : }
4250 :
4251 0 : static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4252 : {
4253 0 : struct vm_area_struct *vma = vmf->vma;
4254 : vm_fault_t ret;
4255 :
4256 0 : if (unlikely(anon_vma_prepare(vma)))
4257 : return VM_FAULT_OOM;
4258 :
4259 0 : vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
4260 0 : if (!vmf->cow_page)
4261 : return VM_FAULT_OOM;
4262 :
4263 0 : if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm,
4264 : GFP_KERNEL)) {
4265 : put_page(vmf->cow_page);
4266 : return VM_FAULT_OOM;
4267 : }
4268 0 : cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
4269 :
4270 0 : ret = __do_fault(vmf);
4271 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4272 : goto uncharge_out;
4273 0 : if (ret & VM_FAULT_DONE_COW)
4274 : return ret;
4275 :
4276 0 : copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4277 0 : __SetPageUptodate(vmf->cow_page);
4278 :
4279 0 : ret |= finish_fault(vmf);
4280 0 : unlock_page(vmf->page);
4281 0 : put_page(vmf->page);
4282 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4283 : goto uncharge_out;
4284 : return ret;
4285 : uncharge_out:
4286 0 : put_page(vmf->cow_page);
4287 0 : return ret;
4288 : }
4289 :
4290 0 : static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4291 : {
4292 0 : struct vm_area_struct *vma = vmf->vma;
4293 : vm_fault_t ret, tmp;
4294 :
4295 0 : ret = __do_fault(vmf);
4296 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4297 : return ret;
4298 :
4299 : /*
4300 : * Check if the backing address space wants to know that the page is
4301 : * about to become writable
4302 : */
4303 0 : if (vma->vm_ops->page_mkwrite) {
4304 0 : unlock_page(vmf->page);
4305 0 : tmp = do_page_mkwrite(vmf);
4306 0 : if (unlikely(!tmp ||
4307 : (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4308 0 : put_page(vmf->page);
4309 0 : return tmp;
4310 : }
4311 : }
4312 :
4313 0 : ret |= finish_fault(vmf);
4314 0 : if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4315 : VM_FAULT_RETRY))) {
4316 0 : unlock_page(vmf->page);
4317 0 : put_page(vmf->page);
4318 0 : return ret;
4319 : }
4320 :
4321 0 : ret |= fault_dirty_shared_page(vmf);
4322 0 : return ret;
4323 : }
4324 :
4325 : /*
4326 : * We enter with non-exclusive mmap_lock (to exclude vma changes,
4327 : * but allow concurrent faults).
4328 : * The mmap_lock may have been released depending on flags and our
4329 : * return value. See filemap_fault() and __folio_lock_or_retry().
4330 : * If mmap_lock is released, vma may become invalid (for example
4331 : * by other thread calling munmap()).
4332 : */
4333 0 : static vm_fault_t do_fault(struct vm_fault *vmf)
4334 : {
4335 0 : struct vm_area_struct *vma = vmf->vma;
4336 0 : struct mm_struct *vm_mm = vma->vm_mm;
4337 : vm_fault_t ret;
4338 :
4339 : /*
4340 : * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4341 : */
4342 0 : if (!vma->vm_ops->fault) {
4343 : /*
4344 : * If we find a migration pmd entry or a none pmd entry, which
4345 : * should never happen, return SIGBUS
4346 : */
4347 0 : if (unlikely(!pmd_present(*vmf->pmd)))
4348 : ret = VM_FAULT_SIGBUS;
4349 : else {
4350 0 : vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
4351 : vmf->pmd,
4352 : vmf->address,
4353 : &vmf->ptl);
4354 : /*
4355 : * Make sure this is not a temporary clearing of pte
4356 : * by holding ptl and checking again. A R/M/W update
4357 : * of pte involves: take ptl, clearing the pte so that
4358 : * we don't have concurrent modification by hardware
4359 : * followed by an update.
4360 : */
4361 0 : if (unlikely(pte_none(*vmf->pte)))
4362 : ret = VM_FAULT_SIGBUS;
4363 : else
4364 0 : ret = VM_FAULT_NOPAGE;
4365 :
4366 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4367 : }
4368 0 : } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4369 0 : ret = do_read_fault(vmf);
4370 0 : else if (!(vma->vm_flags & VM_SHARED))
4371 0 : ret = do_cow_fault(vmf);
4372 : else
4373 0 : ret = do_shared_fault(vmf);
4374 :
4375 : /* preallocated pagetable is unused: free it */
4376 0 : if (vmf->prealloc_pte) {
4377 0 : pte_free(vm_mm, vmf->prealloc_pte);
4378 0 : vmf->prealloc_pte = NULL;
4379 : }
4380 0 : return ret;
4381 : }
4382 :
4383 0 : int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
4384 : unsigned long addr, int page_nid, int *flags)
4385 : {
4386 0 : get_page(page);
4387 :
4388 : count_vm_numa_event(NUMA_HINT_FAULTS);
4389 0 : if (page_nid == numa_node_id()) {
4390 : count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4391 0 : *flags |= TNF_FAULT_LOCAL;
4392 : }
4393 :
4394 0 : return mpol_misplaced(page, vma, addr);
4395 : }
4396 :
4397 : static vm_fault_t do_numa_page(struct vm_fault *vmf)
4398 : {
4399 : struct vm_area_struct *vma = vmf->vma;
4400 : struct page *page = NULL;
4401 : int page_nid = NUMA_NO_NODE;
4402 : int last_cpupid;
4403 : int target_nid;
4404 : pte_t pte, old_pte;
4405 : bool was_writable = pte_savedwrite(vmf->orig_pte);
4406 : int flags = 0;
4407 :
4408 : /*
4409 : * The "pte" at this point cannot be used safely without
4410 : * validation through pte_unmap_same(). It's of NUMA type but
4411 : * the pfn may be screwed if the read is non atomic.
4412 : */
4413 : vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4414 : spin_lock(vmf->ptl);
4415 : if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4416 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4417 : goto out;
4418 : }
4419 :
4420 : /* Get the normal PTE */
4421 : old_pte = ptep_get(vmf->pte);
4422 : pte = pte_modify(old_pte, vma->vm_page_prot);
4423 :
4424 : page = vm_normal_page(vma, vmf->address, pte);
4425 : if (!page)
4426 : goto out_map;
4427 :
4428 : /* TODO: handle PTE-mapped THP */
4429 : if (PageCompound(page))
4430 : goto out_map;
4431 :
4432 : /*
4433 : * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4434 : * much anyway since they can be in shared cache state. This misses
4435 : * the case where a mapping is writable but the process never writes
4436 : * to it but pte_write gets cleared during protection updates and
4437 : * pte_dirty has unpredictable behaviour between PTE scan updates,
4438 : * background writeback, dirty balancing and application behaviour.
4439 : */
4440 : if (!was_writable)
4441 : flags |= TNF_NO_GROUP;
4442 :
4443 : /*
4444 : * Flag if the page is shared between multiple address spaces. This
4445 : * is later used when determining whether to group tasks together
4446 : */
4447 : if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4448 : flags |= TNF_SHARED;
4449 :
4450 : last_cpupid = page_cpupid_last(page);
4451 : page_nid = page_to_nid(page);
4452 : target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4453 : &flags);
4454 : if (target_nid == NUMA_NO_NODE) {
4455 : put_page(page);
4456 : goto out_map;
4457 : }
4458 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4459 :
4460 : /* Migrate to the requested node */
4461 : if (migrate_misplaced_page(page, vma, target_nid)) {
4462 : page_nid = target_nid;
4463 : flags |= TNF_MIGRATED;
4464 : } else {
4465 : flags |= TNF_MIGRATE_FAIL;
4466 : vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4467 : spin_lock(vmf->ptl);
4468 : if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4469 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4470 : goto out;
4471 : }
4472 : goto out_map;
4473 : }
4474 :
4475 : out:
4476 : if (page_nid != NUMA_NO_NODE)
4477 : task_numa_fault(last_cpupid, page_nid, 1, flags);
4478 : return 0;
4479 : out_map:
4480 : /*
4481 : * Make it present again, depending on how arch implements
4482 : * non-accessible ptes, some can allow access by kernel mode.
4483 : */
4484 : old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
4485 : pte = pte_modify(old_pte, vma->vm_page_prot);
4486 : pte = pte_mkyoung(pte);
4487 : if (was_writable)
4488 : pte = pte_mkwrite(pte);
4489 : ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
4490 : update_mmu_cache(vma, vmf->address, vmf->pte);
4491 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4492 : goto out;
4493 : }
4494 :
4495 : static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4496 : {
4497 : if (vma_is_anonymous(vmf->vma))
4498 : return do_huge_pmd_anonymous_page(vmf);
4499 : if (vmf->vma->vm_ops->huge_fault)
4500 : return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4501 : return VM_FAULT_FALLBACK;
4502 : }
4503 :
4504 : /* `inline' is required to avoid gcc 4.1.2 build error */
4505 : static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
4506 : {
4507 : if (vma_is_anonymous(vmf->vma)) {
4508 : if (userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd))
4509 : return handle_userfault(vmf, VM_UFFD_WP);
4510 : return do_huge_pmd_wp_page(vmf);
4511 : }
4512 : if (vmf->vma->vm_ops->huge_fault) {
4513 : vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4514 :
4515 : if (!(ret & VM_FAULT_FALLBACK))
4516 : return ret;
4517 : }
4518 :
4519 : /* COW or write-notify handled on pte level: split pmd. */
4520 : __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4521 :
4522 : return VM_FAULT_FALLBACK;
4523 : }
4524 :
4525 : static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4526 : {
4527 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4528 : defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4529 : /* No support for anonymous transparent PUD pages yet */
4530 : if (vma_is_anonymous(vmf->vma))
4531 : goto split;
4532 : if (vmf->vma->vm_ops->huge_fault) {
4533 : vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4534 :
4535 : if (!(ret & VM_FAULT_FALLBACK))
4536 : return ret;
4537 : }
4538 : split:
4539 : /* COW or write-notify not handled on PUD level: split pud.*/
4540 : __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
4541 : #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4542 : return VM_FAULT_FALLBACK;
4543 : }
4544 :
4545 : static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4546 : {
4547 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4548 : /* No support for anonymous transparent PUD pages yet */
4549 : if (vma_is_anonymous(vmf->vma))
4550 : return VM_FAULT_FALLBACK;
4551 : if (vmf->vma->vm_ops->huge_fault)
4552 : return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4553 : #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4554 : return VM_FAULT_FALLBACK;
4555 : }
4556 :
4557 : /*
4558 : * These routines also need to handle stuff like marking pages dirty
4559 : * and/or accessed for architectures that don't do it in hardware (most
4560 : * RISC architectures). The early dirtying is also good on the i386.
4561 : *
4562 : * There is also a hook called "update_mmu_cache()" that architectures
4563 : * with external mmu caches can use to update those (ie the Sparc or
4564 : * PowerPC hashed page tables that act as extended TLBs).
4565 : *
4566 : * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4567 : * concurrent faults).
4568 : *
4569 : * The mmap_lock may have been released depending on flags and our return value.
4570 : * See filemap_fault() and __folio_lock_or_retry().
4571 : */
4572 0 : static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4573 : {
4574 : pte_t entry;
4575 :
4576 0 : if (unlikely(pmd_none(*vmf->pmd))) {
4577 : /*
4578 : * Leave __pte_alloc() until later: because vm_ops->fault may
4579 : * want to allocate huge page, and if we expose page table
4580 : * for an instant, it will be difficult to retract from
4581 : * concurrent faults and from rmap lookups.
4582 : */
4583 0 : vmf->pte = NULL;
4584 : } else {
4585 : /*
4586 : * If a huge pmd materialized under us just retry later. Use
4587 : * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
4588 : * of pmd_trans_huge() to ensure the pmd didn't become
4589 : * pmd_trans_huge under us and then back to pmd_none, as a
4590 : * result of MADV_DONTNEED running immediately after a huge pmd
4591 : * fault in a different thread of this mm, in turn leading to a
4592 : * misleading pmd_trans_huge() retval. All we have to ensure is
4593 : * that it is a regular pmd that we can walk with
4594 : * pte_offset_map() and we can do that through an atomic read
4595 : * in C, which is what pmd_trans_unstable() provides.
4596 : */
4597 0 : if (pmd_devmap_trans_unstable(vmf->pmd))
4598 : return 0;
4599 : /*
4600 : * A regular pmd is established and it can't morph into a huge
4601 : * pmd from under us anymore at this point because we hold the
4602 : * mmap_lock read mode and khugepaged takes it in write mode.
4603 : * So now it's safe to run pte_offset_map().
4604 : */
4605 0 : vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4606 0 : vmf->orig_pte = *vmf->pte;
4607 :
4608 : /*
4609 : * some architectures can have larger ptes than wordsize,
4610 : * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4611 : * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4612 : * accesses. The code below just needs a consistent view
4613 : * for the ifs and we later double check anyway with the
4614 : * ptl lock held. So here a barrier will do.
4615 : */
4616 0 : barrier();
4617 0 : if (pte_none(vmf->orig_pte)) {
4618 : pte_unmap(vmf->pte);
4619 0 : vmf->pte = NULL;
4620 : }
4621 : }
4622 :
4623 0 : if (!vmf->pte) {
4624 0 : if (vma_is_anonymous(vmf->vma))
4625 0 : return do_anonymous_page(vmf);
4626 : else
4627 0 : return do_fault(vmf);
4628 : }
4629 :
4630 0 : if (!pte_present(vmf->orig_pte))
4631 0 : return do_swap_page(vmf);
4632 :
4633 0 : if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4634 : return do_numa_page(vmf);
4635 :
4636 0 : vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4637 0 : spin_lock(vmf->ptl);
4638 0 : entry = vmf->orig_pte;
4639 0 : if (unlikely(!pte_same(*vmf->pte, entry))) {
4640 : update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
4641 : goto unlock;
4642 : }
4643 0 : if (vmf->flags & FAULT_FLAG_WRITE) {
4644 0 : if (!pte_write(entry))
4645 0 : return do_wp_page(vmf);
4646 : entry = pte_mkdirty(entry);
4647 : }
4648 0 : entry = pte_mkyoung(entry);
4649 0 : if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4650 0 : vmf->flags & FAULT_FLAG_WRITE)) {
4651 : update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4652 : } else {
4653 : /* Skip spurious TLB flush for retried page fault */
4654 0 : if (vmf->flags & FAULT_FLAG_TRIED)
4655 : goto unlock;
4656 : /*
4657 : * This is needed only for protection faults but the arch code
4658 : * is not yet telling us if this is a protection fault or not.
4659 : * This still avoids useless tlb flushes for .text page faults
4660 : * with threads.
4661 : */
4662 0 : if (vmf->flags & FAULT_FLAG_WRITE)
4663 0 : flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4664 : }
4665 : unlock:
4666 0 : pte_unmap_unlock(vmf->pte, vmf->ptl);
4667 0 : return 0;
4668 : }
4669 :
4670 : /*
4671 : * By the time we get here, we already hold the mm semaphore
4672 : *
4673 : * The mmap_lock may have been released depending on flags and our
4674 : * return value. See filemap_fault() and __folio_lock_or_retry().
4675 : */
4676 0 : static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4677 : unsigned long address, unsigned int flags)
4678 : {
4679 0 : struct vm_fault vmf = {
4680 : .vma = vma,
4681 0 : .address = address & PAGE_MASK,
4682 : .real_address = address,
4683 : .flags = flags,
4684 0 : .pgoff = linear_page_index(vma, address),
4685 0 : .gfp_mask = __get_fault_gfp_mask(vma),
4686 : };
4687 0 : unsigned int dirty = flags & FAULT_FLAG_WRITE;
4688 0 : struct mm_struct *mm = vma->vm_mm;
4689 : pgd_t *pgd;
4690 : p4d_t *p4d;
4691 : vm_fault_t ret;
4692 :
4693 0 : pgd = pgd_offset(mm, address);
4694 0 : p4d = p4d_alloc(mm, pgd, address);
4695 0 : if (!p4d)
4696 : return VM_FAULT_OOM;
4697 :
4698 0 : vmf.pud = pud_alloc(mm, p4d, address);
4699 : if (!vmf.pud)
4700 : return VM_FAULT_OOM;
4701 : retry_pud:
4702 : if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
4703 : ret = create_huge_pud(&vmf);
4704 : if (!(ret & VM_FAULT_FALLBACK))
4705 : return ret;
4706 : } else {
4707 : pud_t orig_pud = *vmf.pud;
4708 :
4709 0 : barrier();
4710 0 : if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4711 :
4712 : /* NUMA case for anonymous PUDs would go here */
4713 :
4714 : if (dirty && !pud_write(orig_pud)) {
4715 : ret = wp_huge_pud(&vmf, orig_pud);
4716 : if (!(ret & VM_FAULT_FALLBACK))
4717 : return ret;
4718 : } else {
4719 : huge_pud_set_accessed(&vmf, orig_pud);
4720 : return 0;
4721 : }
4722 : }
4723 : }
4724 :
4725 0 : vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4726 0 : if (!vmf.pmd)
4727 : return VM_FAULT_OOM;
4728 :
4729 : /* Huge pud page fault raced with pmd_alloc? */
4730 0 : if (pud_trans_unstable(vmf.pud))
4731 : goto retry_pud;
4732 :
4733 : if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
4734 : ret = create_huge_pmd(&vmf);
4735 : if (!(ret & VM_FAULT_FALLBACK))
4736 : return ret;
4737 : } else {
4738 0 : vmf.orig_pmd = *vmf.pmd;
4739 :
4740 0 : barrier();
4741 0 : if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
4742 : VM_BUG_ON(thp_migration_supported() &&
4743 : !is_pmd_migration_entry(vmf.orig_pmd));
4744 : if (is_pmd_migration_entry(vmf.orig_pmd))
4745 : pmd_migration_entry_wait(mm, vmf.pmd);
4746 : return 0;
4747 : }
4748 0 : if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
4749 : if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
4750 : return do_huge_pmd_numa_page(&vmf);
4751 :
4752 : if (dirty && !pmd_write(vmf.orig_pmd)) {
4753 : ret = wp_huge_pmd(&vmf);
4754 : if (!(ret & VM_FAULT_FALLBACK))
4755 : return ret;
4756 : } else {
4757 : huge_pmd_set_accessed(&vmf);
4758 : return 0;
4759 : }
4760 : }
4761 : }
4762 :
4763 0 : return handle_pte_fault(&vmf);
4764 : }
4765 :
4766 : /**
4767 : * mm_account_fault - Do page fault accounting
4768 : *
4769 : * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
4770 : * of perf event counters, but we'll still do the per-task accounting to
4771 : * the task who triggered this page fault.
4772 : * @address: the faulted address.
4773 : * @flags: the fault flags.
4774 : * @ret: the fault retcode.
4775 : *
4776 : * This will take care of most of the page fault accounting. Meanwhile, it
4777 : * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
4778 : * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
4779 : * still be in per-arch page fault handlers at the entry of page fault.
4780 : */
4781 0 : static inline void mm_account_fault(struct pt_regs *regs,
4782 : unsigned long address, unsigned int flags,
4783 : vm_fault_t ret)
4784 : {
4785 : bool major;
4786 :
4787 : /*
4788 : * We don't do accounting for some specific faults:
4789 : *
4790 : * - Unsuccessful faults (e.g. when the address wasn't valid). That
4791 : * includes arch_vma_access_permitted() failing before reaching here.
4792 : * So this is not a "this many hardware page faults" counter. We
4793 : * should use the hw profiling for that.
4794 : *
4795 : * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
4796 : * once they're completed.
4797 : */
4798 0 : if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
4799 : return;
4800 :
4801 : /*
4802 : * We define the fault as a major fault when the final successful fault
4803 : * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
4804 : * handle it immediately previously).
4805 : */
4806 0 : major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
4807 :
4808 0 : if (major)
4809 0 : current->maj_flt++;
4810 : else
4811 0 : current->min_flt++;
4812 :
4813 : /*
4814 : * If the fault is done for GUP, regs will be NULL. We only do the
4815 : * accounting for the per thread fault counters who triggered the
4816 : * fault, and we skip the perf event updates.
4817 : */
4818 : if (!regs)
4819 : return;
4820 :
4821 : if (major)
4822 : perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
4823 : else
4824 : perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
4825 : }
4826 :
4827 : /*
4828 : * By the time we get here, we already hold the mm semaphore
4829 : *
4830 : * The mmap_lock may have been released depending on flags and our
4831 : * return value. See filemap_fault() and __folio_lock_or_retry().
4832 : */
4833 0 : vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4834 : unsigned int flags, struct pt_regs *regs)
4835 : {
4836 : vm_fault_t ret;
4837 :
4838 0 : __set_current_state(TASK_RUNNING);
4839 :
4840 0 : count_vm_event(PGFAULT);
4841 0 : count_memcg_event_mm(vma->vm_mm, PGFAULT);
4842 :
4843 : /* do counter updates before entering really critical section. */
4844 0 : check_sync_rss_stat(current);
4845 :
4846 0 : if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4847 0 : flags & FAULT_FLAG_INSTRUCTION,
4848 0 : flags & FAULT_FLAG_REMOTE))
4849 : return VM_FAULT_SIGSEGV;
4850 :
4851 : /*
4852 : * Enable the memcg OOM handling for faults triggered in user
4853 : * space. Kernel faults are handled more gracefully.
4854 : */
4855 0 : if (flags & FAULT_FLAG_USER)
4856 : mem_cgroup_enter_user_fault();
4857 :
4858 0 : if (unlikely(is_vm_hugetlb_page(vma)))
4859 : ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4860 : else
4861 0 : ret = __handle_mm_fault(vma, address, flags);
4862 :
4863 0 : if (flags & FAULT_FLAG_USER) {
4864 : mem_cgroup_exit_user_fault();
4865 : /*
4866 : * The task may have entered a memcg OOM situation but
4867 : * if the allocation error was handled gracefully (no
4868 : * VM_FAULT_OOM), there is no need to kill anything.
4869 : * Just clean up the OOM state peacefully.
4870 : */
4871 0 : if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4872 : mem_cgroup_oom_synchronize(false);
4873 : }
4874 :
4875 0 : mm_account_fault(regs, address, flags, ret);
4876 :
4877 : return ret;
4878 : }
4879 : EXPORT_SYMBOL_GPL(handle_mm_fault);
4880 :
4881 : #ifndef __PAGETABLE_P4D_FOLDED
4882 : /*
4883 : * Allocate p4d page table.
4884 : * We've already handled the fast-path in-line.
4885 : */
4886 : int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4887 : {
4888 : p4d_t *new = p4d_alloc_one(mm, address);
4889 : if (!new)
4890 : return -ENOMEM;
4891 :
4892 : spin_lock(&mm->page_table_lock);
4893 : if (pgd_present(*pgd)) { /* Another has populated it */
4894 : p4d_free(mm, new);
4895 : } else {
4896 : smp_wmb(); /* See comment in pmd_install() */
4897 : pgd_populate(mm, pgd, new);
4898 : }
4899 : spin_unlock(&mm->page_table_lock);
4900 : return 0;
4901 : }
4902 : #endif /* __PAGETABLE_P4D_FOLDED */
4903 :
4904 : #ifndef __PAGETABLE_PUD_FOLDED
4905 : /*
4906 : * Allocate page upper directory.
4907 : * We've already handled the fast-path in-line.
4908 : */
4909 : int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4910 : {
4911 : pud_t *new = pud_alloc_one(mm, address);
4912 : if (!new)
4913 : return -ENOMEM;
4914 :
4915 : spin_lock(&mm->page_table_lock);
4916 : if (!p4d_present(*p4d)) {
4917 : mm_inc_nr_puds(mm);
4918 : smp_wmb(); /* See comment in pmd_install() */
4919 : p4d_populate(mm, p4d, new);
4920 : } else /* Another has populated it */
4921 : pud_free(mm, new);
4922 : spin_unlock(&mm->page_table_lock);
4923 : return 0;
4924 : }
4925 : #endif /* __PAGETABLE_PUD_FOLDED */
4926 :
4927 : #ifndef __PAGETABLE_PMD_FOLDED
4928 : /*
4929 : * Allocate page middle directory.
4930 : * We've already handled the fast-path in-line.
4931 : */
4932 1 : int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4933 : {
4934 : spinlock_t *ptl;
4935 1 : pmd_t *new = pmd_alloc_one(mm, address);
4936 1 : if (!new)
4937 : return -ENOMEM;
4938 :
4939 2 : ptl = pud_lock(mm, pud);
4940 1 : if (!pud_present(*pud)) {
4941 1 : mm_inc_nr_pmds(mm);
4942 1 : smp_wmb(); /* See comment in pmd_install() */
4943 1 : pud_populate(mm, pud, new);
4944 : } else { /* Another has populated it */
4945 0 : pmd_free(mm, new);
4946 : }
4947 1 : spin_unlock(ptl);
4948 1 : return 0;
4949 : }
4950 : #endif /* __PAGETABLE_PMD_FOLDED */
4951 :
4952 0 : int follow_invalidate_pte(struct mm_struct *mm, unsigned long address,
4953 : struct mmu_notifier_range *range, pte_t **ptepp,
4954 : pmd_t **pmdpp, spinlock_t **ptlp)
4955 : {
4956 : pgd_t *pgd;
4957 : p4d_t *p4d;
4958 : pud_t *pud;
4959 : pmd_t *pmd;
4960 : pte_t *ptep;
4961 :
4962 0 : pgd = pgd_offset(mm, address);
4963 : if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4964 : goto out;
4965 :
4966 0 : p4d = p4d_offset(pgd, address);
4967 : if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4968 : goto out;
4969 :
4970 0 : pud = pud_offset(p4d, address);
4971 0 : if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4972 : goto out;
4973 :
4974 0 : pmd = pmd_offset(pud, address);
4975 : VM_BUG_ON(pmd_trans_huge(*pmd));
4976 :
4977 : if (pmd_huge(*pmd)) {
4978 : if (!pmdpp)
4979 : goto out;
4980 :
4981 : if (range) {
4982 : mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0,
4983 : NULL, mm, address & PMD_MASK,
4984 : (address & PMD_MASK) + PMD_SIZE);
4985 : mmu_notifier_invalidate_range_start(range);
4986 : }
4987 : *ptlp = pmd_lock(mm, pmd);
4988 : if (pmd_huge(*pmd)) {
4989 : *pmdpp = pmd;
4990 : return 0;
4991 : }
4992 : spin_unlock(*ptlp);
4993 : if (range)
4994 : mmu_notifier_invalidate_range_end(range);
4995 : }
4996 :
4997 0 : if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4998 : goto out;
4999 :
5000 0 : if (range) {
5001 0 : mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
5002 : address & PAGE_MASK,
5003 : (address & PAGE_MASK) + PAGE_SIZE);
5004 : mmu_notifier_invalidate_range_start(range);
5005 : }
5006 0 : ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
5007 0 : if (!pte_present(*ptep))
5008 : goto unlock;
5009 0 : *ptepp = ptep;
5010 0 : return 0;
5011 : unlock:
5012 0 : pte_unmap_unlock(ptep, *ptlp);
5013 : if (range)
5014 : mmu_notifier_invalidate_range_end(range);
5015 : out:
5016 : return -EINVAL;
5017 : }
5018 :
5019 : /**
5020 : * follow_pte - look up PTE at a user virtual address
5021 : * @mm: the mm_struct of the target address space
5022 : * @address: user virtual address
5023 : * @ptepp: location to store found PTE
5024 : * @ptlp: location to store the lock for the PTE
5025 : *
5026 : * On a successful return, the pointer to the PTE is stored in @ptepp;
5027 : * the corresponding lock is taken and its location is stored in @ptlp.
5028 : * The contents of the PTE are only stable until @ptlp is released;
5029 : * any further use, if any, must be protected against invalidation
5030 : * with MMU notifiers.
5031 : *
5032 : * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
5033 : * should be taken for read.
5034 : *
5035 : * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
5036 : * it is not a good general-purpose API.
5037 : *
5038 : * Return: zero on success, -ve otherwise.
5039 : */
5040 0 : int follow_pte(struct mm_struct *mm, unsigned long address,
5041 : pte_t **ptepp, spinlock_t **ptlp)
5042 : {
5043 0 : return follow_invalidate_pte(mm, address, NULL, ptepp, NULL, ptlp);
5044 : }
5045 : EXPORT_SYMBOL_GPL(follow_pte);
5046 :
5047 : /**
5048 : * follow_pfn - look up PFN at a user virtual address
5049 : * @vma: memory mapping
5050 : * @address: user virtual address
5051 : * @pfn: location to store found PFN
5052 : *
5053 : * Only IO mappings and raw PFN mappings are allowed.
5054 : *
5055 : * This function does not allow the caller to read the permissions
5056 : * of the PTE. Do not use it.
5057 : *
5058 : * Return: zero and the pfn at @pfn on success, -ve otherwise.
5059 : */
5060 0 : int follow_pfn(struct vm_area_struct *vma, unsigned long address,
5061 : unsigned long *pfn)
5062 : {
5063 0 : int ret = -EINVAL;
5064 : spinlock_t *ptl;
5065 : pte_t *ptep;
5066 :
5067 0 : if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5068 : return ret;
5069 :
5070 0 : ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
5071 0 : if (ret)
5072 : return ret;
5073 0 : *pfn = pte_pfn(*ptep);
5074 0 : pte_unmap_unlock(ptep, ptl);
5075 0 : return 0;
5076 : }
5077 : EXPORT_SYMBOL(follow_pfn);
5078 :
5079 : #ifdef CONFIG_HAVE_IOREMAP_PROT
5080 : int follow_phys(struct vm_area_struct *vma,
5081 : unsigned long address, unsigned int flags,
5082 : unsigned long *prot, resource_size_t *phys)
5083 : {
5084 : int ret = -EINVAL;
5085 : pte_t *ptep, pte;
5086 : spinlock_t *ptl;
5087 :
5088 : if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5089 : goto out;
5090 :
5091 : if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
5092 : goto out;
5093 : pte = *ptep;
5094 :
5095 : if ((flags & FOLL_WRITE) && !pte_write(pte))
5096 : goto unlock;
5097 :
5098 : *prot = pgprot_val(pte_pgprot(pte));
5099 : *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5100 :
5101 : ret = 0;
5102 : unlock:
5103 : pte_unmap_unlock(ptep, ptl);
5104 : out:
5105 : return ret;
5106 : }
5107 :
5108 : /**
5109 : * generic_access_phys - generic implementation for iomem mmap access
5110 : * @vma: the vma to access
5111 : * @addr: userspace address, not relative offset within @vma
5112 : * @buf: buffer to read/write
5113 : * @len: length of transfer
5114 : * @write: set to FOLL_WRITE when writing, otherwise reading
5115 : *
5116 : * This is a generic implementation for &vm_operations_struct.access for an
5117 : * iomem mapping. This callback is used by access_process_vm() when the @vma is
5118 : * not page based.
5119 : */
5120 : int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
5121 : void *buf, int len, int write)
5122 : {
5123 : resource_size_t phys_addr;
5124 : unsigned long prot = 0;
5125 : void __iomem *maddr;
5126 : pte_t *ptep, pte;
5127 : spinlock_t *ptl;
5128 : int offset = offset_in_page(addr);
5129 : int ret = -EINVAL;
5130 :
5131 : if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5132 : return -EINVAL;
5133 :
5134 : retry:
5135 : if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5136 : return -EINVAL;
5137 : pte = *ptep;
5138 : pte_unmap_unlock(ptep, ptl);
5139 :
5140 : prot = pgprot_val(pte_pgprot(pte));
5141 : phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5142 :
5143 : if ((write & FOLL_WRITE) && !pte_write(pte))
5144 : return -EINVAL;
5145 :
5146 : maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
5147 : if (!maddr)
5148 : return -ENOMEM;
5149 :
5150 : if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5151 : goto out_unmap;
5152 :
5153 : if (!pte_same(pte, *ptep)) {
5154 : pte_unmap_unlock(ptep, ptl);
5155 : iounmap(maddr);
5156 :
5157 : goto retry;
5158 : }
5159 :
5160 : if (write)
5161 : memcpy_toio(maddr + offset, buf, len);
5162 : else
5163 : memcpy_fromio(buf, maddr + offset, len);
5164 : ret = len;
5165 : pte_unmap_unlock(ptep, ptl);
5166 : out_unmap:
5167 : iounmap(maddr);
5168 :
5169 : return ret;
5170 : }
5171 : EXPORT_SYMBOL_GPL(generic_access_phys);
5172 : #endif
5173 :
5174 : /*
5175 : * Access another process' address space as given in mm.
5176 : */
5177 0 : int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
5178 : int len, unsigned int gup_flags)
5179 : {
5180 : struct vm_area_struct *vma;
5181 0 : void *old_buf = buf;
5182 0 : int write = gup_flags & FOLL_WRITE;
5183 :
5184 0 : if (mmap_read_lock_killable(mm))
5185 : return 0;
5186 :
5187 : /* ignore errors, just check how much was successfully transferred */
5188 0 : while (len) {
5189 : int bytes, ret, offset;
5190 : void *maddr;
5191 0 : struct page *page = NULL;
5192 :
5193 0 : ret = get_user_pages_remote(mm, addr, 1,
5194 : gup_flags, &page, &vma, NULL);
5195 0 : if (ret <= 0) {
5196 : #ifndef CONFIG_HAVE_IOREMAP_PROT
5197 : break;
5198 : #else
5199 : /*
5200 : * Check if this is a VM_IO | VM_PFNMAP VMA, which
5201 : * we can access using slightly different code.
5202 : */
5203 : vma = vma_lookup(mm, addr);
5204 : if (!vma)
5205 : break;
5206 : if (vma->vm_ops && vma->vm_ops->access)
5207 : ret = vma->vm_ops->access(vma, addr, buf,
5208 : len, write);
5209 : if (ret <= 0)
5210 : break;
5211 : bytes = ret;
5212 : #endif
5213 : } else {
5214 0 : bytes = len;
5215 0 : offset = addr & (PAGE_SIZE-1);
5216 0 : if (bytes > PAGE_SIZE-offset)
5217 0 : bytes = PAGE_SIZE-offset;
5218 :
5219 0 : maddr = kmap(page);
5220 0 : if (write) {
5221 0 : copy_to_user_page(vma, page, addr,
5222 : maddr + offset, buf, bytes);
5223 0 : set_page_dirty_lock(page);
5224 : } else {
5225 0 : copy_from_user_page(vma, page, addr,
5226 : buf, maddr + offset, bytes);
5227 : }
5228 0 : kunmap(page);
5229 0 : put_page(page);
5230 : }
5231 0 : len -= bytes;
5232 0 : buf += bytes;
5233 0 : addr += bytes;
5234 : }
5235 0 : mmap_read_unlock(mm);
5236 :
5237 0 : return buf - old_buf;
5238 : }
5239 :
5240 : /**
5241 : * access_remote_vm - access another process' address space
5242 : * @mm: the mm_struct of the target address space
5243 : * @addr: start address to access
5244 : * @buf: source or destination buffer
5245 : * @len: number of bytes to transfer
5246 : * @gup_flags: flags modifying lookup behaviour
5247 : *
5248 : * The caller must hold a reference on @mm.
5249 : *
5250 : * Return: number of bytes copied from source to destination.
5251 : */
5252 0 : int access_remote_vm(struct mm_struct *mm, unsigned long addr,
5253 : void *buf, int len, unsigned int gup_flags)
5254 : {
5255 0 : return __access_remote_vm(mm, addr, buf, len, gup_flags);
5256 : }
5257 :
5258 : /*
5259 : * Access another process' address space.
5260 : * Source/target buffer must be kernel space,
5261 : * Do not walk the page table directly, use get_user_pages
5262 : */
5263 0 : int access_process_vm(struct task_struct *tsk, unsigned long addr,
5264 : void *buf, int len, unsigned int gup_flags)
5265 : {
5266 : struct mm_struct *mm;
5267 : int ret;
5268 :
5269 0 : mm = get_task_mm(tsk);
5270 0 : if (!mm)
5271 : return 0;
5272 :
5273 0 : ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
5274 :
5275 0 : mmput(mm);
5276 :
5277 0 : return ret;
5278 : }
5279 : EXPORT_SYMBOL_GPL(access_process_vm);
5280 :
5281 : /*
5282 : * Print the name of a VMA.
5283 : */
5284 0 : void print_vma_addr(char *prefix, unsigned long ip)
5285 : {
5286 0 : struct mm_struct *mm = current->mm;
5287 : struct vm_area_struct *vma;
5288 :
5289 : /*
5290 : * we might be running from an atomic context so we cannot sleep
5291 : */
5292 0 : if (!mmap_read_trylock(mm))
5293 : return;
5294 :
5295 0 : vma = find_vma(mm, ip);
5296 0 : if (vma && vma->vm_file) {
5297 0 : struct file *f = vma->vm_file;
5298 0 : char *buf = (char *)__get_free_page(GFP_NOWAIT);
5299 0 : if (buf) {
5300 : char *p;
5301 :
5302 0 : p = file_path(f, buf, PAGE_SIZE);
5303 0 : if (IS_ERR(p))
5304 0 : p = "?";
5305 0 : printk("%s%s[%lx+%lx]", prefix, kbasename(p),
5306 : vma->vm_start,
5307 : vma->vm_end - vma->vm_start);
5308 0 : free_page((unsigned long)buf);
5309 : }
5310 : }
5311 : mmap_read_unlock(mm);
5312 : }
5313 :
5314 : #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5315 : void __might_fault(const char *file, int line)
5316 : {
5317 : if (pagefault_disabled())
5318 : return;
5319 : __might_sleep(file, line);
5320 : #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5321 : if (current->mm)
5322 : might_lock_read(¤t->mm->mmap_lock);
5323 : #endif
5324 : }
5325 : EXPORT_SYMBOL(__might_fault);
5326 : #endif
5327 :
5328 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5329 : /*
5330 : * Process all subpages of the specified huge page with the specified
5331 : * operation. The target subpage will be processed last to keep its
5332 : * cache lines hot.
5333 : */
5334 : static inline void process_huge_page(
5335 : unsigned long addr_hint, unsigned int pages_per_huge_page,
5336 : void (*process_subpage)(unsigned long addr, int idx, void *arg),
5337 : void *arg)
5338 : {
5339 : int i, n, base, l;
5340 : unsigned long addr = addr_hint &
5341 : ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5342 :
5343 : /* Process target subpage last to keep its cache lines hot */
5344 : might_sleep();
5345 : n = (addr_hint - addr) / PAGE_SIZE;
5346 : if (2 * n <= pages_per_huge_page) {
5347 : /* If target subpage in first half of huge page */
5348 : base = 0;
5349 : l = n;
5350 : /* Process subpages at the end of huge page */
5351 : for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
5352 : cond_resched();
5353 : process_subpage(addr + i * PAGE_SIZE, i, arg);
5354 : }
5355 : } else {
5356 : /* If target subpage in second half of huge page */
5357 : base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
5358 : l = pages_per_huge_page - n;
5359 : /* Process subpages at the begin of huge page */
5360 : for (i = 0; i < base; i++) {
5361 : cond_resched();
5362 : process_subpage(addr + i * PAGE_SIZE, i, arg);
5363 : }
5364 : }
5365 : /*
5366 : * Process remaining subpages in left-right-left-right pattern
5367 : * towards the target subpage
5368 : */
5369 : for (i = 0; i < l; i++) {
5370 : int left_idx = base + i;
5371 : int right_idx = base + 2 * l - 1 - i;
5372 :
5373 : cond_resched();
5374 : process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
5375 : cond_resched();
5376 : process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
5377 : }
5378 : }
5379 :
5380 : static void clear_gigantic_page(struct page *page,
5381 : unsigned long addr,
5382 : unsigned int pages_per_huge_page)
5383 : {
5384 : int i;
5385 : struct page *p = page;
5386 :
5387 : might_sleep();
5388 : for (i = 0; i < pages_per_huge_page;
5389 : i++, p = mem_map_next(p, page, i)) {
5390 : cond_resched();
5391 : clear_user_highpage(p, addr + i * PAGE_SIZE);
5392 : }
5393 : }
5394 :
5395 : static void clear_subpage(unsigned long addr, int idx, void *arg)
5396 : {
5397 : struct page *page = arg;
5398 :
5399 : clear_user_highpage(page + idx, addr);
5400 : }
5401 :
5402 : void clear_huge_page(struct page *page,
5403 : unsigned long addr_hint, unsigned int pages_per_huge_page)
5404 : {
5405 : unsigned long addr = addr_hint &
5406 : ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5407 :
5408 : if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5409 : clear_gigantic_page(page, addr, pages_per_huge_page);
5410 : return;
5411 : }
5412 :
5413 : process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
5414 : }
5415 :
5416 : static void copy_user_gigantic_page(struct page *dst, struct page *src,
5417 : unsigned long addr,
5418 : struct vm_area_struct *vma,
5419 : unsigned int pages_per_huge_page)
5420 : {
5421 : int i;
5422 : struct page *dst_base = dst;
5423 : struct page *src_base = src;
5424 :
5425 : for (i = 0; i < pages_per_huge_page; ) {
5426 : cond_resched();
5427 : copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
5428 :
5429 : i++;
5430 : dst = mem_map_next(dst, dst_base, i);
5431 : src = mem_map_next(src, src_base, i);
5432 : }
5433 : }
5434 :
5435 : struct copy_subpage_arg {
5436 : struct page *dst;
5437 : struct page *src;
5438 : struct vm_area_struct *vma;
5439 : };
5440 :
5441 : static void copy_subpage(unsigned long addr, int idx, void *arg)
5442 : {
5443 : struct copy_subpage_arg *copy_arg = arg;
5444 :
5445 : copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
5446 : addr, copy_arg->vma);
5447 : }
5448 :
5449 : void copy_user_huge_page(struct page *dst, struct page *src,
5450 : unsigned long addr_hint, struct vm_area_struct *vma,
5451 : unsigned int pages_per_huge_page)
5452 : {
5453 : unsigned long addr = addr_hint &
5454 : ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5455 : struct copy_subpage_arg arg = {
5456 : .dst = dst,
5457 : .src = src,
5458 : .vma = vma,
5459 : };
5460 :
5461 : if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5462 : copy_user_gigantic_page(dst, src, addr, vma,
5463 : pages_per_huge_page);
5464 : return;
5465 : }
5466 :
5467 : process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
5468 : }
5469 :
5470 : long copy_huge_page_from_user(struct page *dst_page,
5471 : const void __user *usr_src,
5472 : unsigned int pages_per_huge_page,
5473 : bool allow_pagefault)
5474 : {
5475 : void *page_kaddr;
5476 : unsigned long i, rc = 0;
5477 : unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
5478 : struct page *subpage = dst_page;
5479 :
5480 : for (i = 0; i < pages_per_huge_page;
5481 : i++, subpage = mem_map_next(subpage, dst_page, i)) {
5482 : if (allow_pagefault)
5483 : page_kaddr = kmap(subpage);
5484 : else
5485 : page_kaddr = kmap_atomic(subpage);
5486 : rc = copy_from_user(page_kaddr,
5487 : usr_src + i * PAGE_SIZE, PAGE_SIZE);
5488 : if (allow_pagefault)
5489 : kunmap(subpage);
5490 : else
5491 : kunmap_atomic(page_kaddr);
5492 :
5493 : ret_val -= (PAGE_SIZE - rc);
5494 : if (rc)
5495 : break;
5496 :
5497 : flush_dcache_page(subpage);
5498 :
5499 : cond_resched();
5500 : }
5501 : return ret_val;
5502 : }
5503 : #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5504 :
5505 : #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5506 :
5507 : static struct kmem_cache *page_ptl_cachep;
5508 :
5509 : void __init ptlock_cache_init(void)
5510 : {
5511 : page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
5512 : SLAB_PANIC, NULL);
5513 : }
5514 :
5515 : bool ptlock_alloc(struct page *page)
5516 : {
5517 : spinlock_t *ptl;
5518 :
5519 : ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
5520 : if (!ptl)
5521 : return false;
5522 : page->ptl = ptl;
5523 : return true;
5524 : }
5525 :
5526 : void ptlock_free(struct page *page)
5527 : {
5528 : kmem_cache_free(page_ptl_cachep, page->ptl);
5529 : }
5530 : #endif
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