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Merge tag 'cxl-fixes-6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
[linux.git] / mm / gup.c
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457c8996 1// SPDX-License-Identifier: GPL-2.0-only
4bbd4c77
KS
2#include <linux/kernel.h>
3#include <linux/errno.h>
4#include <linux/err.h>
5#include <linux/spinlock.h>
6
4bbd4c77 7#include <linux/mm.h>
3565fce3 8#include <linux/memremap.h>
4bbd4c77
KS
9#include <linux/pagemap.h>
10#include <linux/rmap.h>
11#include <linux/swap.h>
12#include <linux/swapops.h>
1507f512 13#include <linux/secretmem.h>
4bbd4c77 14
174cd4b1 15#include <linux/sched/signal.h>
2667f50e 16#include <linux/rwsem.h>
f30c59e9 17#include <linux/hugetlb.h>
9a4e9f3b
AK
18#include <linux/migrate.h>
19#include <linux/mm_inline.h>
20#include <linux/sched/mm.h>
a6e79df9 21#include <linux/shmem_fs.h>
1027e443 22
33a709b2 23#include <asm/mmu_context.h>
1027e443 24#include <asm/tlbflush.h>
2667f50e 25
4bbd4c77
KS
26#include "internal.h"
27
df06b37f
KB
28struct follow_page_context {
29 struct dev_pagemap *pgmap;
30 unsigned int page_mask;
31};
32
b6a2619c
DH
33static inline void sanity_check_pinned_pages(struct page **pages,
34 unsigned long npages)
35{
36 if (!IS_ENABLED(CONFIG_DEBUG_VM))
37 return;
38
39 /*
40 * We only pin anonymous pages if they are exclusive. Once pinned, we
41 * can no longer turn them possibly shared and PageAnonExclusive() will
42 * stick around until the page is freed.
43 *
44 * We'd like to verify that our pinned anonymous pages are still mapped
45 * exclusively. The issue with anon THP is that we don't know how
46 * they are/were mapped when pinning them. However, for anon
47 * THP we can assume that either the given page (PTE-mapped THP) or
48 * the head page (PMD-mapped THP) should be PageAnonExclusive(). If
49 * neither is the case, there is certainly something wrong.
50 */
51 for (; npages; npages--, pages++) {
52 struct page *page = *pages;
53 struct folio *folio = page_folio(page);
54
c8070b78
DH
55 if (is_zero_page(page) ||
56 !folio_test_anon(folio))
b6a2619c
DH
57 continue;
58 if (!folio_test_large(folio) || folio_test_hugetlb(folio))
59 VM_BUG_ON_PAGE(!PageAnonExclusive(&folio->page), page);
60 else
61 /* Either a PTE-mapped or a PMD-mapped THP. */
62 VM_BUG_ON_PAGE(!PageAnonExclusive(&folio->page) &&
63 !PageAnonExclusive(page), page);
64 }
65}
66
cd1adf1b 67/*
ece1ed7b 68 * Return the folio with ref appropriately incremented,
cd1adf1b 69 * or NULL if that failed.
a707cdd5 70 */
ece1ed7b 71static inline struct folio *try_get_folio(struct page *page, int refs)
a707cdd5 72{
ece1ed7b 73 struct folio *folio;
a707cdd5 74
59409373 75retry:
ece1ed7b
MWO
76 folio = page_folio(page);
77 if (WARN_ON_ONCE(folio_ref_count(folio) < 0))
a707cdd5 78 return NULL;
ece1ed7b 79 if (unlikely(!folio_ref_try_add_rcu(folio, refs)))
a707cdd5 80 return NULL;
c24d3732
JH
81
82 /*
ece1ed7b
MWO
83 * At this point we have a stable reference to the folio; but it
84 * could be that between calling page_folio() and the refcount
85 * increment, the folio was split, in which case we'd end up
86 * holding a reference on a folio that has nothing to do with the page
c24d3732 87 * we were given anymore.
ece1ed7b
MWO
88 * So now that the folio is stable, recheck that the page still
89 * belongs to this folio.
c24d3732 90 */
ece1ed7b 91 if (unlikely(page_folio(page) != folio)) {
f4f451a1
MS
92 if (!put_devmap_managed_page_refs(&folio->page, refs))
93 folio_put_refs(folio, refs);
59409373 94 goto retry;
c24d3732
JH
95 }
96
ece1ed7b 97 return folio;
a707cdd5
JH
98}
99
3967db22 100/**
ece1ed7b 101 * try_grab_folio() - Attempt to get or pin a folio.
3967db22 102 * @page: pointer to page to be grabbed
ece1ed7b 103 * @refs: the value to (effectively) add to the folio's refcount
3967db22
JH
104 * @flags: gup flags: these are the FOLL_* flag values.
105 *
3faa52c0 106 * "grab" names in this file mean, "look at flags to decide whether to use
ece1ed7b 107 * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount.
3faa52c0
JH
108 *
109 * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the
110 * same time. (That's true throughout the get_user_pages*() and
111 * pin_user_pages*() APIs.) Cases:
112 *
ece1ed7b 113 * FOLL_GET: folio's refcount will be incremented by @refs.
3967db22 114 *
ece1ed7b 115 * FOLL_PIN on large folios: folio's refcount will be incremented by
94688e8e 116 * @refs, and its pincount will be incremented by @refs.
3967db22 117 *
ece1ed7b 118 * FOLL_PIN on single-page folios: folio's refcount will be incremented by
5232c63f 119 * @refs * GUP_PIN_COUNTING_BIAS.
3faa52c0 120 *
ece1ed7b
MWO
121 * Return: The folio containing @page (with refcount appropriately
122 * incremented) for success, or NULL upon failure. If neither FOLL_GET
123 * nor FOLL_PIN was set, that's considered failure, and furthermore,
124 * a likely bug in the caller, so a warning is also emitted.
3faa52c0 125 */
ece1ed7b 126struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags)
3faa52c0 127{
503670ee
VMO
128 struct folio *folio;
129
130 if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0))
131 return NULL;
132
4003f107
LG
133 if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
134 return NULL;
135
3faa52c0 136 if (flags & FOLL_GET)
ece1ed7b 137 return try_get_folio(page, refs);
ece1ed7b 138
503670ee 139 /* FOLL_PIN is set */
c8070b78 140
6e17c6de
LT
141 /*
142 * Don't take a pin on the zero page - it's not going anywhere
143 * and it is used in a *lot* of places.
144 */
145 if (is_zero_page(page))
146 return page_folio(page);
df3a0a21 147
6e17c6de 148 folio = try_get_folio(page, refs);
503670ee
VMO
149 if (!folio)
150 return NULL;
c24d3732 151
503670ee
VMO
152 /*
153 * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
154 * right zone, so fail and let the caller fall back to the slow
155 * path.
156 */
157 if (unlikely((flags & FOLL_LONGTERM) &&
158 !folio_is_longterm_pinnable(folio))) {
159 if (!put_devmap_managed_page_refs(&folio->page, refs))
160 folio_put_refs(folio, refs);
161 return NULL;
3faa52c0 162 }
088b8aa5 163
503670ee
VMO
164 /*
165 * When pinning a large folio, use an exact count to track it.
166 *
167 * However, be sure to *also* increment the normal folio
168 * refcount field at least once, so that the folio really
169 * is pinned. That's why the refcount from the earlier
170 * try_get_folio() is left intact.
171 */
172 if (folio_test_large(folio))
173 atomic_add(refs, &folio->_pincount);
174 else
175 folio_ref_add(folio,
176 refs * (GUP_PIN_COUNTING_BIAS - 1));
177 /*
178 * Adjust the pincount before re-checking the PTE for changes.
179 * This is essentially a smp_mb() and is paired with a memory
e3b4b137 180 * barrier in folio_try_share_anon_rmap_*().
503670ee
VMO
181 */
182 smp_mb__after_atomic();
47e29d32 183
503670ee 184 node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
3faa52c0 185
503670ee 186 return folio;
3faa52c0
JH
187}
188
d8ddc099 189static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
4509b42c
JG
190{
191 if (flags & FOLL_PIN) {
c8070b78
DH
192 if (is_zero_folio(folio))
193 return;
d8ddc099
MWO
194 node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs);
195 if (folio_test_large(folio))
94688e8e 196 atomic_sub(refs, &folio->_pincount);
4509b42c
JG
197 else
198 refs *= GUP_PIN_COUNTING_BIAS;
199 }
200
f4f451a1
MS
201 if (!put_devmap_managed_page_refs(&folio->page, refs))
202 folio_put_refs(folio, refs);
4509b42c
JG
203}
204
3faa52c0
JH
205/**
206 * try_grab_page() - elevate a page's refcount by a flag-dependent amount
5fec0719
MWO
207 * @page: pointer to page to be grabbed
208 * @flags: gup flags: these are the FOLL_* flag values.
3faa52c0
JH
209 *
210 * This might not do anything at all, depending on the flags argument.
211 *
212 * "grab" names in this file mean, "look at flags to decide whether to use
213 * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
214 *
3faa52c0 215 * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same
ece1ed7b 216 * time. Cases: please see the try_grab_folio() documentation, with
3967db22 217 * "refs=1".
3faa52c0 218 *
0f089235
LG
219 * Return: 0 for success, or if no action was required (if neither FOLL_PIN
220 * nor FOLL_GET was set, nothing is done). A negative error code for failure:
221 *
222 * -ENOMEM FOLL_GET or FOLL_PIN was set, but the page could not
223 * be grabbed.
3faa52c0 224 */
0f089235 225int __must_check try_grab_page(struct page *page, unsigned int flags)
3faa52c0 226{
5fec0719
MWO
227 struct folio *folio = page_folio(page);
228
5fec0719 229 if (WARN_ON_ONCE(folio_ref_count(folio) <= 0))
0f089235 230 return -ENOMEM;
3faa52c0 231
4003f107
LG
232 if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
233 return -EREMOTEIO;
3faa52c0 234
c36c04c2 235 if (flags & FOLL_GET)
5fec0719 236 folio_ref_inc(folio);
c36c04c2 237 else if (flags & FOLL_PIN) {
c8070b78
DH
238 /*
239 * Don't take a pin on the zero page - it's not going anywhere
240 * and it is used in a *lot* of places.
241 */
242 if (is_zero_page(page))
243 return 0;
244
c36c04c2 245 /*
5fec0719 246 * Similar to try_grab_folio(): be sure to *also*
78d9d6ce
MWO
247 * increment the normal page refcount field at least once,
248 * so that the page really is pinned.
c36c04c2 249 */
5fec0719
MWO
250 if (folio_test_large(folio)) {
251 folio_ref_add(folio, 1);
94688e8e 252 atomic_add(1, &folio->_pincount);
8ea2979c 253 } else {
5fec0719 254 folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);
8ea2979c 255 }
c36c04c2 256
5fec0719 257 node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1);
c36c04c2
JH
258 }
259
0f089235 260 return 0;
3faa52c0
JH
261}
262
3faa52c0
JH
263/**
264 * unpin_user_page() - release a dma-pinned page
265 * @page: pointer to page to be released
266 *
267 * Pages that were pinned via pin_user_pages*() must be released via either
268 * unpin_user_page(), or one of the unpin_user_pages*() routines. This is so
269 * that such pages can be separately tracked and uniquely handled. In
270 * particular, interactions with RDMA and filesystems need special handling.
271 */
272void unpin_user_page(struct page *page)
273{
b6a2619c 274 sanity_check_pinned_pages(&page, 1);
d8ddc099 275 gup_put_folio(page_folio(page), 1, FOLL_PIN);
3faa52c0
JH
276}
277EXPORT_SYMBOL(unpin_user_page);
278
1101fb8f
DH
279/**
280 * folio_add_pin - Try to get an additional pin on a pinned folio
281 * @folio: The folio to be pinned
282 *
283 * Get an additional pin on a folio we already have a pin on. Makes no change
284 * if the folio is a zero_page.
285 */
286void folio_add_pin(struct folio *folio)
287{
288 if (is_zero_folio(folio))
289 return;
290
291 /*
292 * Similar to try_grab_folio(): be sure to *also* increment the normal
293 * page refcount field at least once, so that the page really is
294 * pinned.
295 */
296 if (folio_test_large(folio)) {
297 WARN_ON_ONCE(atomic_read(&folio->_pincount) < 1);
298 folio_ref_inc(folio);
299 atomic_inc(&folio->_pincount);
300 } else {
301 WARN_ON_ONCE(folio_ref_count(folio) < GUP_PIN_COUNTING_BIAS);
302 folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);
303 }
304}
305
659508f9 306static inline struct folio *gup_folio_range_next(struct page *start,
8f39f5fc 307 unsigned long npages, unsigned long i, unsigned int *ntails)
458a4f78 308{
659508f9
MWO
309 struct page *next = nth_page(start, i);
310 struct folio *folio = page_folio(next);
458a4f78
JM
311 unsigned int nr = 1;
312
659508f9 313 if (folio_test_large(folio))
4c654229 314 nr = min_t(unsigned int, npages - i,
659508f9 315 folio_nr_pages(folio) - folio_page_idx(folio, next));
458a4f78 316
458a4f78 317 *ntails = nr;
659508f9 318 return folio;
458a4f78
JM
319}
320
12521c76 321static inline struct folio *gup_folio_next(struct page **list,
28297dbc 322 unsigned long npages, unsigned long i, unsigned int *ntails)
8745d7f6 323{
12521c76 324 struct folio *folio = page_folio(list[i]);
8745d7f6
JM
325 unsigned int nr;
326
8745d7f6 327 for (nr = i + 1; nr < npages; nr++) {
12521c76 328 if (page_folio(list[nr]) != folio)
8745d7f6
JM
329 break;
330 }
331
8745d7f6 332 *ntails = nr - i;
12521c76 333 return folio;
8745d7f6
JM
334}
335
fc1d8e7c 336/**
f1f6a7dd 337 * unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
2d15eb31 338 * @pages: array of pages to be maybe marked dirty, and definitely released.
fc1d8e7c 339 * @npages: number of pages in the @pages array.
2d15eb31 340 * @make_dirty: whether to mark the pages dirty
fc1d8e7c
JH
341 *
342 * "gup-pinned page" refers to a page that has had one of the get_user_pages()
343 * variants called on that page.
344 *
345 * For each page in the @pages array, make that page (or its head page, if a
2d15eb31 346 * compound page) dirty, if @make_dirty is true, and if the page was previously
f1f6a7dd
JH
347 * listed as clean. In any case, releases all pages using unpin_user_page(),
348 * possibly via unpin_user_pages(), for the non-dirty case.
fc1d8e7c 349 *
f1f6a7dd 350 * Please see the unpin_user_page() documentation for details.
fc1d8e7c 351 *
2d15eb31
AM
352 * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is
353 * required, then the caller should a) verify that this is really correct,
354 * because _lock() is usually required, and b) hand code it:
f1f6a7dd 355 * set_page_dirty_lock(), unpin_user_page().
fc1d8e7c
JH
356 *
357 */
f1f6a7dd
JH
358void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
359 bool make_dirty)
fc1d8e7c 360{
12521c76
MWO
361 unsigned long i;
362 struct folio *folio;
363 unsigned int nr;
2d15eb31
AM
364
365 if (!make_dirty) {
f1f6a7dd 366 unpin_user_pages(pages, npages);
2d15eb31
AM
367 return;
368 }
369
b6a2619c 370 sanity_check_pinned_pages(pages, npages);
12521c76
MWO
371 for (i = 0; i < npages; i += nr) {
372 folio = gup_folio_next(pages, npages, i, &nr);
2d15eb31
AM
373 /*
374 * Checking PageDirty at this point may race with
375 * clear_page_dirty_for_io(), but that's OK. Two key
376 * cases:
377 *
378 * 1) This code sees the page as already dirty, so it
379 * skips the call to set_page_dirty(). That could happen
380 * because clear_page_dirty_for_io() called
381 * page_mkclean(), followed by set_page_dirty().
382 * However, now the page is going to get written back,
383 * which meets the original intention of setting it
384 * dirty, so all is well: clear_page_dirty_for_io() goes
385 * on to call TestClearPageDirty(), and write the page
386 * back.
387 *
388 * 2) This code sees the page as clean, so it calls
389 * set_page_dirty(). The page stays dirty, despite being
390 * written back, so it gets written back again in the
391 * next writeback cycle. This is harmless.
392 */
12521c76
MWO
393 if (!folio_test_dirty(folio)) {
394 folio_lock(folio);
395 folio_mark_dirty(folio);
396 folio_unlock(folio);
397 }
398 gup_put_folio(folio, nr, FOLL_PIN);
2d15eb31 399 }
fc1d8e7c 400}
f1f6a7dd 401EXPORT_SYMBOL(unpin_user_pages_dirty_lock);
fc1d8e7c 402
458a4f78
JM
403/**
404 * unpin_user_page_range_dirty_lock() - release and optionally dirty
405 * gup-pinned page range
406 *
407 * @page: the starting page of a range maybe marked dirty, and definitely released.
408 * @npages: number of consecutive pages to release.
409 * @make_dirty: whether to mark the pages dirty
410 *
411 * "gup-pinned page range" refers to a range of pages that has had one of the
412 * pin_user_pages() variants called on that page.
413 *
414 * For the page ranges defined by [page .. page+npages], make that range (or
415 * its head pages, if a compound page) dirty, if @make_dirty is true, and if the
416 * page range was previously listed as clean.
417 *
418 * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is
419 * required, then the caller should a) verify that this is really correct,
420 * because _lock() is usually required, and b) hand code it:
421 * set_page_dirty_lock(), unpin_user_page().
422 *
423 */
424void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,
425 bool make_dirty)
426{
659508f9
MWO
427 unsigned long i;
428 struct folio *folio;
429 unsigned int nr;
430
431 for (i = 0; i < npages; i += nr) {
432 folio = gup_folio_range_next(page, npages, i, &nr);
433 if (make_dirty && !folio_test_dirty(folio)) {
434 folio_lock(folio);
435 folio_mark_dirty(folio);
436 folio_unlock(folio);
437 }
438 gup_put_folio(folio, nr, FOLL_PIN);
458a4f78
JM
439 }
440}
441EXPORT_SYMBOL(unpin_user_page_range_dirty_lock);
442
b6a2619c
DH
443static void unpin_user_pages_lockless(struct page **pages, unsigned long npages)
444{
445 unsigned long i;
446 struct folio *folio;
447 unsigned int nr;
448
449 /*
450 * Don't perform any sanity checks because we might have raced with
451 * fork() and some anonymous pages might now actually be shared --
452 * which is why we're unpinning after all.
453 */
454 for (i = 0; i < npages; i += nr) {
455 folio = gup_folio_next(pages, npages, i, &nr);
456 gup_put_folio(folio, nr, FOLL_PIN);
457 }
458}
459
fc1d8e7c 460/**
f1f6a7dd 461 * unpin_user_pages() - release an array of gup-pinned pages.
fc1d8e7c
JH
462 * @pages: array of pages to be marked dirty and released.
463 * @npages: number of pages in the @pages array.
464 *
f1f6a7dd 465 * For each page in the @pages array, release the page using unpin_user_page().
fc1d8e7c 466 *
f1f6a7dd 467 * Please see the unpin_user_page() documentation for details.
fc1d8e7c 468 */
f1f6a7dd 469void unpin_user_pages(struct page **pages, unsigned long npages)
fc1d8e7c 470{
12521c76
MWO
471 unsigned long i;
472 struct folio *folio;
473 unsigned int nr;
fc1d8e7c 474
146608bb
JH
475 /*
476 * If this WARN_ON() fires, then the system *might* be leaking pages (by
477 * leaving them pinned), but probably not. More likely, gup/pup returned
478 * a hard -ERRNO error to the caller, who erroneously passed it here.
479 */
480 if (WARN_ON(IS_ERR_VALUE(npages)))
481 return;
31b912de 482
b6a2619c 483 sanity_check_pinned_pages(pages, npages);
12521c76
MWO
484 for (i = 0; i < npages; i += nr) {
485 folio = gup_folio_next(pages, npages, i, &nr);
486 gup_put_folio(folio, nr, FOLL_PIN);
e7602748 487 }
fc1d8e7c 488}
f1f6a7dd 489EXPORT_SYMBOL(unpin_user_pages);
fc1d8e7c 490
a458b76a
AA
491/*
492 * Set the MMF_HAS_PINNED if not set yet; after set it'll be there for the mm's
493 * lifecycle. Avoid setting the bit unless necessary, or it might cause write
494 * cache bouncing on large SMP machines for concurrent pinned gups.
495 */
496static inline void mm_set_has_pinned_flag(unsigned long *mm_flags)
497{
498 if (!test_bit(MMF_HAS_PINNED, mm_flags))
499 set_bit(MMF_HAS_PINNED, mm_flags);
500}
501
050a9adc 502#ifdef CONFIG_MMU
69e68b4f
KS
503static struct page *no_page_table(struct vm_area_struct *vma,
504 unsigned int flags)
4bbd4c77 505{
69e68b4f
KS
506 /*
507 * When core dumping an enormous anonymous area that nobody
508 * has touched so far, we don't want to allocate unnecessary pages or
509 * page tables. Return error instead of NULL to skip handle_mm_fault,
510 * then get_dump_page() will return NULL to leave a hole in the dump.
511 * But we can only make this optimization where a hole would surely
512 * be zero-filled if handle_mm_fault() actually did handle it.
513 */
a0137f16
AK
514 if ((flags & FOLL_DUMP) &&
515 (vma_is_anonymous(vma) || !vma->vm_ops->fault))
69e68b4f
KS
516 return ERR_PTR(-EFAULT);
517 return NULL;
518}
4bbd4c77 519
1027e443
KS
520static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
521 pte_t *pte, unsigned int flags)
522{
1027e443 523 if (flags & FOLL_TOUCH) {
c33c7948
RR
524 pte_t orig_entry = ptep_get(pte);
525 pte_t entry = orig_entry;
1027e443
KS
526
527 if (flags & FOLL_WRITE)
528 entry = pte_mkdirty(entry);
529 entry = pte_mkyoung(entry);
530
c33c7948 531 if (!pte_same(orig_entry, entry)) {
1027e443
KS
532 set_pte_at(vma->vm_mm, address, pte, entry);
533 update_mmu_cache(vma, address, pte);
534 }
535 }
536
537 /* Proper page table entry exists, but no corresponding struct page */
538 return -EEXIST;
539}
540
5535be30
DH
541/* FOLL_FORCE can write to even unwritable PTEs in COW mappings. */
542static inline bool can_follow_write_pte(pte_t pte, struct page *page,
543 struct vm_area_struct *vma,
544 unsigned int flags)
19be0eaf 545{
5535be30
DH
546 /* If the pte is writable, we can write to the page. */
547 if (pte_write(pte))
548 return true;
549
550 /* Maybe FOLL_FORCE is set to override it? */
551 if (!(flags & FOLL_FORCE))
552 return false;
553
554 /* But FOLL_FORCE has no effect on shared mappings */
555 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
556 return false;
557
558 /* ... or read-only private ones */
559 if (!(vma->vm_flags & VM_MAYWRITE))
560 return false;
561
562 /* ... or already writable ones that just need to take a write fault */
563 if (vma->vm_flags & VM_WRITE)
564 return false;
565
566 /*
567 * See can_change_pte_writable(): we broke COW and could map the page
568 * writable if we have an exclusive anonymous page ...
569 */
570 if (!page || !PageAnon(page) || !PageAnonExclusive(page))
571 return false;
572
573 /* ... and a write-fault isn't required for other reasons. */
574 if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
575 return false;
576 return !userfaultfd_pte_wp(vma, pte);
19be0eaf
LT
577}
578
69e68b4f 579static struct page *follow_page_pte(struct vm_area_struct *vma,
df06b37f
KB
580 unsigned long address, pmd_t *pmd, unsigned int flags,
581 struct dev_pagemap **pgmap)
69e68b4f
KS
582{
583 struct mm_struct *mm = vma->vm_mm;
584 struct page *page;
585 spinlock_t *ptl;
586 pte_t *ptep, pte;
f28d4363 587 int ret;
4bbd4c77 588
eddb1c22
JH
589 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
590 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
591 (FOLL_PIN | FOLL_GET)))
592 return ERR_PTR(-EINVAL);
4bbd4c77
KS
593
594 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
04dee9e8
HD
595 if (!ptep)
596 return no_page_table(vma, flags);
c33c7948 597 pte = ptep_get(ptep);
f7355e99
DH
598 if (!pte_present(pte))
599 goto no_page;
d74943a2 600 if (pte_protnone(pte) && !gup_can_follow_protnone(vma, flags))
4bbd4c77 601 goto no_page;
4bbd4c77
KS
602
603 page = vm_normal_page(vma, address, pte);
5535be30
DH
604
605 /*
606 * We only care about anon pages in can_follow_write_pte() and don't
607 * have to worry about pte_devmap() because they are never anon.
608 */
609 if ((flags & FOLL_WRITE) &&
610 !can_follow_write_pte(pte, page, vma, flags)) {
611 page = NULL;
612 goto out;
613 }
614
3faa52c0 615 if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
3565fce3 616 /*
3faa52c0
JH
617 * Only return device mapping pages in the FOLL_GET or FOLL_PIN
618 * case since they are only valid while holding the pgmap
619 * reference.
3565fce3 620 */
df06b37f
KB
621 *pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap);
622 if (*pgmap)
3565fce3
DW
623 page = pte_page(pte);
624 else
625 goto no_page;
626 } else if (unlikely(!page)) {
1027e443
KS
627 if (flags & FOLL_DUMP) {
628 /* Avoid special (like zero) pages in core dumps */
629 page = ERR_PTR(-EFAULT);
630 goto out;
631 }
632
633 if (is_zero_pfn(pte_pfn(pte))) {
634 page = pte_page(pte);
635 } else {
1027e443
KS
636 ret = follow_pfn_pte(vma, address, ptep, flags);
637 page = ERR_PTR(ret);
638 goto out;
639 }
4bbd4c77
KS
640 }
641
84209e87 642 if (!pte_write(pte) && gup_must_unshare(vma, flags, page)) {
a7f22660
DH
643 page = ERR_PTR(-EMLINK);
644 goto out;
645 }
b6a2619c
DH
646
647 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
648 !PageAnonExclusive(page), page);
649
3faa52c0 650 /* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
0f089235
LG
651 ret = try_grab_page(page, flags);
652 if (unlikely(ret)) {
653 page = ERR_PTR(ret);
3faa52c0 654 goto out;
8fde12ca 655 }
4003f107 656
f28d4363
CI
657 /*
658 * We need to make the page accessible if and only if we are going
659 * to access its content (the FOLL_PIN case). Please see
660 * Documentation/core-api/pin_user_pages.rst for details.
661 */
662 if (flags & FOLL_PIN) {
663 ret = arch_make_page_accessible(page);
664 if (ret) {
665 unpin_user_page(page);
666 page = ERR_PTR(ret);
667 goto out;
668 }
669 }
4bbd4c77
KS
670 if (flags & FOLL_TOUCH) {
671 if ((flags & FOLL_WRITE) &&
672 !pte_dirty(pte) && !PageDirty(page))
673 set_page_dirty(page);
674 /*
675 * pte_mkyoung() would be more correct here, but atomic care
676 * is needed to avoid losing the dirty bit: it is easier to use
677 * mark_page_accessed().
678 */
679 mark_page_accessed(page);
680 }
1027e443 681out:
4bbd4c77 682 pte_unmap_unlock(ptep, ptl);
4bbd4c77 683 return page;
4bbd4c77
KS
684no_page:
685 pte_unmap_unlock(ptep, ptl);
686 if (!pte_none(pte))
69e68b4f
KS
687 return NULL;
688 return no_page_table(vma, flags);
689}
690
080dbb61
AK
691static struct page *follow_pmd_mask(struct vm_area_struct *vma,
692 unsigned long address, pud_t *pudp,
df06b37f
KB
693 unsigned int flags,
694 struct follow_page_context *ctx)
69e68b4f 695{
68827280 696 pmd_t *pmd, pmdval;
69e68b4f
KS
697 spinlock_t *ptl;
698 struct page *page;
699 struct mm_struct *mm = vma->vm_mm;
700
080dbb61 701 pmd = pmd_offset(pudp, address);
26e1a0c3 702 pmdval = pmdp_get_lockless(pmd);
68827280 703 if (pmd_none(pmdval))
69e68b4f 704 return no_page_table(vma, flags);
f7355e99 705 if (!pmd_present(pmdval))
e66f17ff 706 return no_page_table(vma, flags);
68827280 707 if (pmd_devmap(pmdval)) {
3565fce3 708 ptl = pmd_lock(mm, pmd);
df06b37f 709 page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
3565fce3
DW
710 spin_unlock(ptl);
711 if (page)
712 return page;
e9119fb6 713 return no_page_table(vma, flags);
3565fce3 714 }
68827280 715 if (likely(!pmd_trans_huge(pmdval)))
df06b37f 716 return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
6742d293 717
d74943a2 718 if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))
db08f203
AK
719 return no_page_table(vma, flags);
720
6742d293 721 ptl = pmd_lock(mm, pmd);
84c3fc4e
ZY
722 if (unlikely(!pmd_present(*pmd))) {
723 spin_unlock(ptl);
f7355e99 724 return no_page_table(vma, flags);
84c3fc4e 725 }
6742d293
KS
726 if (unlikely(!pmd_trans_huge(*pmd))) {
727 spin_unlock(ptl);
df06b37f 728 return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
6742d293 729 }
4066c119 730 if (flags & FOLL_SPLIT_PMD) {
2378118b
HD
731 spin_unlock(ptl);
732 split_huge_pmd(vma, pmd, address);
733 /* If pmd was left empty, stuff a page table in there quickly */
734 return pte_alloc(mm, pmd) ? ERR_PTR(-ENOMEM) :
df06b37f 735 follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
69e68b4f 736 }
6742d293
KS
737 page = follow_trans_huge_pmd(vma, address, pmd, flags);
738 spin_unlock(ptl);
df06b37f 739 ctx->page_mask = HPAGE_PMD_NR - 1;
6742d293 740 return page;
4bbd4c77
KS
741}
742
080dbb61
AK
743static struct page *follow_pud_mask(struct vm_area_struct *vma,
744 unsigned long address, p4d_t *p4dp,
df06b37f
KB
745 unsigned int flags,
746 struct follow_page_context *ctx)
080dbb61
AK
747{
748 pud_t *pud;
749 spinlock_t *ptl;
750 struct page *page;
751 struct mm_struct *mm = vma->vm_mm;
752
753 pud = pud_offset(p4dp, address);
754 if (pud_none(*pud))
755 return no_page_table(vma, flags);
080dbb61
AK
756 if (pud_devmap(*pud)) {
757 ptl = pud_lock(mm, pud);
df06b37f 758 page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap);
080dbb61
AK
759 spin_unlock(ptl);
760 if (page)
761 return page;
e9119fb6 762 return no_page_table(vma, flags);
080dbb61
AK
763 }
764 if (unlikely(pud_bad(*pud)))
765 return no_page_table(vma, flags);
766
df06b37f 767 return follow_pmd_mask(vma, address, pud, flags, ctx);
080dbb61
AK
768}
769
080dbb61
AK
770static struct page *follow_p4d_mask(struct vm_area_struct *vma,
771 unsigned long address, pgd_t *pgdp,
df06b37f
KB
772 unsigned int flags,
773 struct follow_page_context *ctx)
080dbb61
AK
774{
775 p4d_t *p4d;
776
777 p4d = p4d_offset(pgdp, address);
778 if (p4d_none(*p4d))
779 return no_page_table(vma, flags);
780 BUILD_BUG_ON(p4d_huge(*p4d));
781 if (unlikely(p4d_bad(*p4d)))
782 return no_page_table(vma, flags);
783
df06b37f 784 return follow_pud_mask(vma, address, p4d, flags, ctx);
080dbb61
AK
785}
786
787/**
788 * follow_page_mask - look up a page descriptor from a user-virtual address
789 * @vma: vm_area_struct mapping @address
790 * @address: virtual address to look up
791 * @flags: flags modifying lookup behaviour
78179556
MR
792 * @ctx: contains dev_pagemap for %ZONE_DEVICE memory pinning and a
793 * pointer to output page_mask
080dbb61
AK
794 *
795 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
796 *
78179556
MR
797 * When getting pages from ZONE_DEVICE memory, the @ctx->pgmap caches
798 * the device's dev_pagemap metadata to avoid repeating expensive lookups.
799 *
a7f22660
DH
800 * When getting an anonymous page and the caller has to trigger unsharing
801 * of a shared anonymous page first, -EMLINK is returned. The caller should
802 * trigger a fault with FAULT_FLAG_UNSHARE set. Note that unsharing is only
803 * relevant with FOLL_PIN and !FOLL_WRITE.
804 *
78179556
MR
805 * On output, the @ctx->page_mask is set according to the size of the page.
806 *
807 * Return: the mapped (struct page *), %NULL if no mapping exists, or
080dbb61
AK
808 * an error pointer if there is a mapping to something not represented
809 * by a page descriptor (see also vm_normal_page()).
810 */
a7030aea 811static struct page *follow_page_mask(struct vm_area_struct *vma,
080dbb61 812 unsigned long address, unsigned int flags,
df06b37f 813 struct follow_page_context *ctx)
080dbb61
AK
814{
815 pgd_t *pgd;
080dbb61
AK
816 struct mm_struct *mm = vma->vm_mm;
817
df06b37f 818 ctx->page_mask = 0;
080dbb61 819
57a196a5
MK
820 /*
821 * Call hugetlb_follow_page_mask for hugetlb vmas as it will use
822 * special hugetlb page table walking code. This eliminates the
823 * need to check for hugetlb entries in the general walking code.
57a196a5 824 */
dd767aaa 825 if (is_vm_hugetlb_page(vma))
5502ea44
PX
826 return hugetlb_follow_page_mask(vma, address, flags,
827 &ctx->page_mask);
080dbb61
AK
828
829 pgd = pgd_offset(mm, address);
830
831 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
832 return no_page_table(vma, flags);
833
df06b37f
KB
834 return follow_p4d_mask(vma, address, pgd, flags, ctx);
835}
836
837struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
838 unsigned int foll_flags)
839{
840 struct follow_page_context ctx = { NULL };
841 struct page *page;
842
1507f512
MR
843 if (vma_is_secretmem(vma))
844 return NULL;
845
d64e2dbc 846 if (WARN_ON_ONCE(foll_flags & FOLL_PIN))
8909691b
DH
847 return NULL;
848
d74943a2
DH
849 /*
850 * We never set FOLL_HONOR_NUMA_FAULT because callers don't expect
851 * to fail on PROT_NONE-mapped pages.
852 */
df06b37f
KB
853 page = follow_page_mask(vma, address, foll_flags, &ctx);
854 if (ctx.pgmap)
855 put_dev_pagemap(ctx.pgmap);
856 return page;
080dbb61
AK
857}
858
f2b495ca
KS
859static int get_gate_page(struct mm_struct *mm, unsigned long address,
860 unsigned int gup_flags, struct vm_area_struct **vma,
861 struct page **page)
862{
863 pgd_t *pgd;
c2febafc 864 p4d_t *p4d;
f2b495ca
KS
865 pud_t *pud;
866 pmd_t *pmd;
867 pte_t *pte;
c33c7948 868 pte_t entry;
f2b495ca
KS
869 int ret = -EFAULT;
870
871 /* user gate pages are read-only */
872 if (gup_flags & FOLL_WRITE)
873 return -EFAULT;
874 if (address > TASK_SIZE)
875 pgd = pgd_offset_k(address);
876 else
877 pgd = pgd_offset_gate(mm, address);
b5d1c39f
AL
878 if (pgd_none(*pgd))
879 return -EFAULT;
c2febafc 880 p4d = p4d_offset(pgd, address);
b5d1c39f
AL
881 if (p4d_none(*p4d))
882 return -EFAULT;
c2febafc 883 pud = pud_offset(p4d, address);
b5d1c39f
AL
884 if (pud_none(*pud))
885 return -EFAULT;
f2b495ca 886 pmd = pmd_offset(pud, address);
84c3fc4e 887 if (!pmd_present(*pmd))
f2b495ca 888 return -EFAULT;
f2b495ca 889 pte = pte_offset_map(pmd, address);
04dee9e8
HD
890 if (!pte)
891 return -EFAULT;
c33c7948
RR
892 entry = ptep_get(pte);
893 if (pte_none(entry))
f2b495ca
KS
894 goto unmap;
895 *vma = get_gate_vma(mm);
896 if (!page)
897 goto out;
c33c7948 898 *page = vm_normal_page(*vma, address, entry);
f2b495ca 899 if (!*page) {
c33c7948 900 if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(entry)))
f2b495ca 901 goto unmap;
c33c7948 902 *page = pte_page(entry);
f2b495ca 903 }
0f089235
LG
904 ret = try_grab_page(*page, gup_flags);
905 if (unlikely(ret))
8fde12ca 906 goto unmap;
f2b495ca
KS
907out:
908 ret = 0;
909unmap:
910 pte_unmap(pte);
911 return ret;
912}
913
9a95f3cf 914/*
9a863a6a
JG
915 * mmap_lock must be held on entry. If @flags has FOLL_UNLOCKABLE but not
916 * FOLL_NOWAIT, the mmap_lock may be released. If it is, *@locked will be set
917 * to 0 and -EBUSY returned.
9a95f3cf 918 */
64019a2e 919static int faultin_page(struct vm_area_struct *vma,
a7f22660
DH
920 unsigned long address, unsigned int *flags, bool unshare,
921 int *locked)
16744483 922{
16744483 923 unsigned int fault_flags = 0;
2b740303 924 vm_fault_t ret;
16744483 925
55b8fe70
AG
926 if (*flags & FOLL_NOFAULT)
927 return -EFAULT;
16744483
KS
928 if (*flags & FOLL_WRITE)
929 fault_flags |= FAULT_FLAG_WRITE;
1b2ee126
DH
930 if (*flags & FOLL_REMOTE)
931 fault_flags |= FAULT_FLAG_REMOTE;
f04740f5 932 if (*flags & FOLL_UNLOCKABLE) {
71335f37 933 fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
93c5c61d
PX
934 /*
935 * FAULT_FLAG_INTERRUPTIBLE is opt-in. GUP callers must set
936 * FOLL_INTERRUPTIBLE to enable FAULT_FLAG_INTERRUPTIBLE.
937 * That's because some callers may not be prepared to
938 * handle early exits caused by non-fatal signals.
939 */
940 if (*flags & FOLL_INTERRUPTIBLE)
941 fault_flags |= FAULT_FLAG_INTERRUPTIBLE;
942 }
16744483
KS
943 if (*flags & FOLL_NOWAIT)
944 fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
234b239b 945 if (*flags & FOLL_TRIED) {
4426e945
PX
946 /*
947 * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED
948 * can co-exist
949 */
234b239b
ALC
950 fault_flags |= FAULT_FLAG_TRIED;
951 }
a7f22660
DH
952 if (unshare) {
953 fault_flags |= FAULT_FLAG_UNSHARE;
954 /* FAULT_FLAG_WRITE and FAULT_FLAG_UNSHARE are incompatible */
955 VM_BUG_ON(fault_flags & FAULT_FLAG_WRITE);
956 }
16744483 957
bce617ed 958 ret = handle_mm_fault(vma, address, fault_flags, NULL);
d9272525
PX
959
960 if (ret & VM_FAULT_COMPLETED) {
961 /*
962 * With FAULT_FLAG_RETRY_NOWAIT we'll never release the
963 * mmap lock in the page fault handler. Sanity check this.
964 */
965 WARN_ON_ONCE(fault_flags & FAULT_FLAG_RETRY_NOWAIT);
9a863a6a
JG
966 *locked = 0;
967
d9272525
PX
968 /*
969 * We should do the same as VM_FAULT_RETRY, but let's not
970 * return -EBUSY since that's not reflecting the reality of
971 * what has happened - we've just fully completed a page
972 * fault, with the mmap lock released. Use -EAGAIN to show
973 * that we want to take the mmap lock _again_.
974 */
975 return -EAGAIN;
976 }
977
16744483 978 if (ret & VM_FAULT_ERROR) {
9a291a7c
JM
979 int err = vm_fault_to_errno(ret, *flags);
980
981 if (err)
982 return err;
16744483
KS
983 BUG();
984 }
985
16744483 986 if (ret & VM_FAULT_RETRY) {
9a863a6a 987 if (!(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
4f6da934 988 *locked = 0;
16744483
KS
989 return -EBUSY;
990 }
991
16744483
KS
992 return 0;
993}
994
8ac26843
LS
995/*
996 * Writing to file-backed mappings which require folio dirty tracking using GUP
997 * is a fundamentally broken operation, as kernel write access to GUP mappings
998 * do not adhere to the semantics expected by a file system.
999 *
1000 * Consider the following scenario:-
1001 *
1002 * 1. A folio is written to via GUP which write-faults the memory, notifying
1003 * the file system and dirtying the folio.
1004 * 2. Later, writeback is triggered, resulting in the folio being cleaned and
1005 * the PTE being marked read-only.
1006 * 3. The GUP caller writes to the folio, as it is mapped read/write via the
1007 * direct mapping.
1008 * 4. The GUP caller, now done with the page, unpins it and sets it dirty
1009 * (though it does not have to).
1010 *
1011 * This results in both data being written to a folio without writenotify, and
1012 * the folio being dirtied unexpectedly (if the caller decides to do so).
1013 */
1014static bool writable_file_mapping_allowed(struct vm_area_struct *vma,
1015 unsigned long gup_flags)
1016{
1017 /*
1018 * If we aren't pinning then no problematic write can occur. A long term
1019 * pin is the most egregious case so this is the case we disallow.
1020 */
1021 if ((gup_flags & (FOLL_PIN | FOLL_LONGTERM)) !=
1022 (FOLL_PIN | FOLL_LONGTERM))
1023 return true;
1024
1025 /*
1026 * If the VMA does not require dirty tracking then no problematic write
1027 * can occur either.
1028 */
1029 return !vma_needs_dirty_tracking(vma);
1030}
1031
fa5bb209
KS
1032static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
1033{
1034 vm_flags_t vm_flags = vma->vm_flags;
1b2ee126
DH
1035 int write = (gup_flags & FOLL_WRITE);
1036 int foreign = (gup_flags & FOLL_REMOTE);
8ac26843 1037 bool vma_anon = vma_is_anonymous(vma);
fa5bb209
KS
1038
1039 if (vm_flags & (VM_IO | VM_PFNMAP))
1040 return -EFAULT;
1041
8ac26843 1042 if ((gup_flags & FOLL_ANON) && !vma_anon)
7f7ccc2c
WT
1043 return -EFAULT;
1044
52650c8b
JG
1045 if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma))
1046 return -EOPNOTSUPP;
1047
1507f512
MR
1048 if (vma_is_secretmem(vma))
1049 return -EFAULT;
1050
1b2ee126 1051 if (write) {
8ac26843
LS
1052 if (!vma_anon &&
1053 !writable_file_mapping_allowed(vma, gup_flags))
1054 return -EFAULT;
1055
6beb9958 1056 if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) {
fa5bb209
KS
1057 if (!(gup_flags & FOLL_FORCE))
1058 return -EFAULT;
f347454d
DH
1059 /* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */
1060 if (is_vm_hugetlb_page(vma))
1061 return -EFAULT;
fa5bb209
KS
1062 /*
1063 * We used to let the write,force case do COW in a
1064 * VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could
1065 * set a breakpoint in a read-only mapping of an
1066 * executable, without corrupting the file (yet only
1067 * when that file had been opened for writing!).
1068 * Anon pages in shared mappings are surprising: now
1069 * just reject it.
1070 */
46435364 1071 if (!is_cow_mapping(vm_flags))
fa5bb209 1072 return -EFAULT;
fa5bb209
KS
1073 }
1074 } else if (!(vm_flags & VM_READ)) {
1075 if (!(gup_flags & FOLL_FORCE))
1076 return -EFAULT;
1077 /*
1078 * Is there actually any vma we can reach here which does not
1079 * have VM_MAYREAD set?
1080 */
1081 if (!(vm_flags & VM_MAYREAD))
1082 return -EFAULT;
1083 }
d61172b4
DH
1084 /*
1085 * gups are always data accesses, not instruction
1086 * fetches, so execute=false here
1087 */
1088 if (!arch_vma_access_permitted(vma, write, false, foreign))
33a709b2 1089 return -EFAULT;
fa5bb209
KS
1090 return 0;
1091}
1092
6cd06ab1
LT
1093/*
1094 * This is "vma_lookup()", but with a warning if we would have
1095 * historically expanded the stack in the GUP code.
1096 */
1097static struct vm_area_struct *gup_vma_lookup(struct mm_struct *mm,
1098 unsigned long addr)
1099{
1100#ifdef CONFIG_STACK_GROWSUP
1101 return vma_lookup(mm, addr);
1102#else
1103 static volatile unsigned long next_warn;
1104 struct vm_area_struct *vma;
1105 unsigned long now, next;
1106
1107 vma = find_vma(mm, addr);
1108 if (!vma || (addr >= vma->vm_start))
1109 return vma;
1110
1111 /* Only warn for half-way relevant accesses */
1112 if (!(vma->vm_flags & VM_GROWSDOWN))
1113 return NULL;
1114 if (vma->vm_start - addr > 65536)
1115 return NULL;
1116
1117 /* Let's not warn more than once an hour.. */
1118 now = jiffies; next = next_warn;
1119 if (next && time_before(now, next))
1120 return NULL;
1121 next_warn = now + 60*60*HZ;
1122
1123 /* Let people know things may have changed. */
1124 pr_warn("GUP no longer grows the stack in %s (%d): %lx-%lx (%lx)\n",
1125 current->comm, task_pid_nr(current),
1126 vma->vm_start, vma->vm_end, addr);
1127 dump_stack();
1128 return NULL;
1129#endif
1130}
1131
4bbd4c77
KS
1132/**
1133 * __get_user_pages() - pin user pages in memory
4bbd4c77
KS
1134 * @mm: mm_struct of target mm
1135 * @start: starting user address
1136 * @nr_pages: number of pages from start to pin
1137 * @gup_flags: flags modifying pin behaviour
1138 * @pages: array that receives pointers to the pages pinned.
1139 * Should be at least nr_pages long. Or NULL, if caller
1140 * only intends to ensure the pages are faulted in.
c1e8d7c6 1141 * @locked: whether we're still with the mmap_lock held
4bbd4c77 1142 *
d2dfbe47
LX
1143 * Returns either number of pages pinned (which may be less than the
1144 * number requested), or an error. Details about the return value:
1145 *
1146 * -- If nr_pages is 0, returns 0.
1147 * -- If nr_pages is >0, but no pages were pinned, returns -errno.
1148 * -- If nr_pages is >0, and some pages were pinned, returns the number of
1149 * pages pinned. Again, this may be less than nr_pages.
2d3a36a4 1150 * -- 0 return value is possible when the fault would need to be retried.
d2dfbe47
LX
1151 *
1152 * The caller is responsible for releasing returned @pages, via put_page().
1153 *
c1e8d7c6 1154 * Must be called with mmap_lock held. It may be released. See below.
4bbd4c77
KS
1155 *
1156 * __get_user_pages walks a process's page tables and takes a reference to
1157 * each struct page that each user address corresponds to at a given
1158 * instant. That is, it takes the page that would be accessed if a user
1159 * thread accesses the given user virtual address at that instant.
1160 *
1161 * This does not guarantee that the page exists in the user mappings when
1162 * __get_user_pages returns, and there may even be a completely different
1163 * page there in some cases (eg. if mmapped pagecache has been invalidated
c5acf1f6 1164 * and subsequently re-faulted). However it does guarantee that the page
4bbd4c77
KS
1165 * won't be freed completely. And mostly callers simply care that the page
1166 * contains data that was valid *at some point in time*. Typically, an IO
1167 * or similar operation cannot guarantee anything stronger anyway because
1168 * locks can't be held over the syscall boundary.
1169 *
1170 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1171 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1172 * appropriate) must be called after the page is finished with, and
1173 * before put_page is called.
1174 *
9a863a6a
JG
1175 * If FOLL_UNLOCKABLE is set without FOLL_NOWAIT then the mmap_lock may
1176 * be released. If this happens *@locked will be set to 0 on return.
9a95f3cf 1177 *
9a863a6a
JG
1178 * A caller using such a combination of @gup_flags must therefore hold the
1179 * mmap_lock for reading only, and recognize when it's been released. Otherwise,
1180 * it must be held for either reading or writing and will not be released.
4bbd4c77
KS
1181 *
1182 * In most cases, get_user_pages or get_user_pages_fast should be used
1183 * instead of __get_user_pages. __get_user_pages should be used only if
1184 * you need some special @gup_flags.
1185 */
64019a2e 1186static long __get_user_pages(struct mm_struct *mm,
4bbd4c77
KS
1187 unsigned long start, unsigned long nr_pages,
1188 unsigned int gup_flags, struct page **pages,
b2cac248 1189 int *locked)
4bbd4c77 1190{
df06b37f 1191 long ret = 0, i = 0;
fa5bb209 1192 struct vm_area_struct *vma = NULL;
df06b37f 1193 struct follow_page_context ctx = { NULL };
4bbd4c77
KS
1194
1195 if (!nr_pages)
1196 return 0;
1197
428e106a 1198 start = untagged_addr_remote(mm, start);
f9652594 1199
eddb1c22 1200 VM_BUG_ON(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN)));
4bbd4c77 1201
4bbd4c77 1202 do {
fa5bb209
KS
1203 struct page *page;
1204 unsigned int foll_flags = gup_flags;
1205 unsigned int page_increm;
1206
1207 /* first iteration or cross vma bound */
1208 if (!vma || start >= vma->vm_end) {
6cd06ab1 1209 vma = gup_vma_lookup(mm, start);
fa5bb209 1210 if (!vma && in_gate_area(mm, start)) {
fa5bb209
KS
1211 ret = get_gate_page(mm, start & PAGE_MASK,
1212 gup_flags, &vma,
ffe1e786 1213 pages ? &page : NULL);
fa5bb209 1214 if (ret)
08be37b7 1215 goto out;
df06b37f 1216 ctx.page_mask = 0;
fa5bb209
KS
1217 goto next_page;
1218 }
4bbd4c77 1219
52650c8b 1220 if (!vma) {
df06b37f
KB
1221 ret = -EFAULT;
1222 goto out;
1223 }
52650c8b
JG
1224 ret = check_vma_flags(vma, gup_flags);
1225 if (ret)
1226 goto out;
fa5bb209
KS
1227 }
1228retry:
1229 /*
1230 * If we have a pending SIGKILL, don't keep faulting pages and
1231 * potentially allocating memory.
1232 */
fa45f116 1233 if (fatal_signal_pending(current)) {
d180870d 1234 ret = -EINTR;
df06b37f
KB
1235 goto out;
1236 }
fa5bb209 1237 cond_resched();
df06b37f
KB
1238
1239 page = follow_page_mask(vma, start, foll_flags, &ctx);
a7f22660
DH
1240 if (!page || PTR_ERR(page) == -EMLINK) {
1241 ret = faultin_page(vma, start, &foll_flags,
1242 PTR_ERR(page) == -EMLINK, locked);
fa5bb209
KS
1243 switch (ret) {
1244 case 0:
1245 goto retry;
df06b37f 1246 case -EBUSY:
d9272525 1247 case -EAGAIN:
df06b37f 1248 ret = 0;
e4a9bc58 1249 fallthrough;
fa5bb209
KS
1250 case -EFAULT:
1251 case -ENOMEM:
1252 case -EHWPOISON:
df06b37f 1253 goto out;
4bbd4c77 1254 }
fa5bb209 1255 BUG();
1027e443
KS
1256 } else if (PTR_ERR(page) == -EEXIST) {
1257 /*
1258 * Proper page table entry exists, but no corresponding
65462462
JH
1259 * struct page. If the caller expects **pages to be
1260 * filled in, bail out now, because that can't be done
1261 * for this page.
1027e443 1262 */
65462462
JH
1263 if (pages) {
1264 ret = PTR_ERR(page);
1265 goto out;
1266 }
1027e443 1267 } else if (IS_ERR(page)) {
df06b37f
KB
1268 ret = PTR_ERR(page);
1269 goto out;
1027e443 1270 }
ffe1e786 1271next_page:
df06b37f 1272 page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.page_mask);
fa5bb209
KS
1273 if (page_increm > nr_pages)
1274 page_increm = nr_pages;
57edfcfd
PX
1275
1276 if (pages) {
1277 struct page *subpage;
1278 unsigned int j;
1279
1280 /*
1281 * This must be a large folio (and doesn't need to
1282 * be the whole folio; it can be part of it), do
1283 * the refcount work for all the subpages too.
1284 *
1285 * NOTE: here the page may not be the head page
1286 * e.g. when start addr is not thp-size aligned.
1287 * try_grab_folio() should have taken care of tail
1288 * pages.
1289 */
1290 if (page_increm > 1) {
1291 struct folio *folio;
1292
1293 /*
1294 * Since we already hold refcount on the
1295 * large folio, this should never fail.
1296 */
1297 folio = try_grab_folio(page, page_increm - 1,
1298 foll_flags);
1299 if (WARN_ON_ONCE(!folio)) {
1300 /*
1301 * Release the 1st page ref if the
1302 * folio is problematic, fail hard.
1303 */
1304 gup_put_folio(page_folio(page), 1,
1305 foll_flags);
1306 ret = -EFAULT;
1307 goto out;
1308 }
1309 }
1310
1311 for (j = 0; j < page_increm; j++) {
1312 subpage = nth_page(page, j);
1313 pages[i + j] = subpage;
1314 flush_anon_page(vma, subpage, start + j * PAGE_SIZE);
1315 flush_dcache_page(subpage);
1316 }
1317 }
1318
fa5bb209
KS
1319 i += page_increm;
1320 start += page_increm * PAGE_SIZE;
1321 nr_pages -= page_increm;
4bbd4c77 1322 } while (nr_pages);
df06b37f
KB
1323out:
1324 if (ctx.pgmap)
1325 put_dev_pagemap(ctx.pgmap);
1326 return i ? i : ret;
4bbd4c77 1327}
4bbd4c77 1328
771ab430
TK
1329static bool vma_permits_fault(struct vm_area_struct *vma,
1330 unsigned int fault_flags)
d4925e00 1331{
1b2ee126
DH
1332 bool write = !!(fault_flags & FAULT_FLAG_WRITE);
1333 bool foreign = !!(fault_flags & FAULT_FLAG_REMOTE);
33a709b2 1334 vm_flags_t vm_flags = write ? VM_WRITE : VM_READ;
d4925e00
DH
1335
1336 if (!(vm_flags & vma->vm_flags))
1337 return false;
1338
33a709b2
DH
1339 /*
1340 * The architecture might have a hardware protection
1b2ee126 1341 * mechanism other than read/write that can deny access.
d61172b4
DH
1342 *
1343 * gup always represents data access, not instruction
1344 * fetches, so execute=false here:
33a709b2 1345 */
d61172b4 1346 if (!arch_vma_access_permitted(vma, write, false, foreign))
33a709b2
DH
1347 return false;
1348
d4925e00
DH
1349 return true;
1350}
1351
adc8cb40 1352/**
4bbd4c77 1353 * fixup_user_fault() - manually resolve a user page fault
4bbd4c77
KS
1354 * @mm: mm_struct of target mm
1355 * @address: user address
1356 * @fault_flags:flags to pass down to handle_mm_fault()
c1e8d7c6 1357 * @unlocked: did we unlock the mmap_lock while retrying, maybe NULL if caller
548b6a1e
MC
1358 * does not allow retry. If NULL, the caller must guarantee
1359 * that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY.
4bbd4c77
KS
1360 *
1361 * This is meant to be called in the specific scenario where for locking reasons
1362 * we try to access user memory in atomic context (within a pagefault_disable()
1363 * section), this returns -EFAULT, and we want to resolve the user fault before
1364 * trying again.
1365 *
1366 * Typically this is meant to be used by the futex code.
1367 *
1368 * The main difference with get_user_pages() is that this function will
1369 * unconditionally call handle_mm_fault() which will in turn perform all the
1370 * necessary SW fixup of the dirty and young bits in the PTE, while
4a9e1cda 1371 * get_user_pages() only guarantees to update these in the struct page.
4bbd4c77
KS
1372 *
1373 * This is important for some architectures where those bits also gate the
1374 * access permission to the page because they are maintained in software. On
1375 * such architectures, gup() will not be enough to make a subsequent access
1376 * succeed.
1377 *
c1e8d7c6
ML
1378 * This function will not return with an unlocked mmap_lock. So it has not the
1379 * same semantics wrt the @mm->mmap_lock as does filemap_fault().
4bbd4c77 1380 */
64019a2e 1381int fixup_user_fault(struct mm_struct *mm,
4a9e1cda
DD
1382 unsigned long address, unsigned int fault_flags,
1383 bool *unlocked)
4bbd4c77
KS
1384{
1385 struct vm_area_struct *vma;
8fed2f3c 1386 vm_fault_t ret;
4a9e1cda 1387
428e106a 1388 address = untagged_addr_remote(mm, address);
f9652594 1389
4a9e1cda 1390 if (unlocked)
71335f37 1391 fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
4bbd4c77 1392
4a9e1cda 1393retry:
6cd06ab1 1394 vma = gup_vma_lookup(mm, address);
8d7071af 1395 if (!vma)
4bbd4c77
KS
1396 return -EFAULT;
1397
d4925e00 1398 if (!vma_permits_fault(vma, fault_flags))
4bbd4c77
KS
1399 return -EFAULT;
1400
475f4dfc
PX
1401 if ((fault_flags & FAULT_FLAG_KILLABLE) &&
1402 fatal_signal_pending(current))
1403 return -EINTR;
1404
bce617ed 1405 ret = handle_mm_fault(vma, address, fault_flags, NULL);
d9272525
PX
1406
1407 if (ret & VM_FAULT_COMPLETED) {
1408 /*
1409 * NOTE: it's a pity that we need to retake the lock here
1410 * to pair with the unlock() in the callers. Ideally we
1411 * could tell the callers so they do not need to unlock.
1412 */
1413 mmap_read_lock(mm);
1414 *unlocked = true;
1415 return 0;
1416 }
1417
4bbd4c77 1418 if (ret & VM_FAULT_ERROR) {
9a291a7c
JM
1419 int err = vm_fault_to_errno(ret, 0);
1420
1421 if (err)
1422 return err;
4bbd4c77
KS
1423 BUG();
1424 }
4a9e1cda
DD
1425
1426 if (ret & VM_FAULT_RETRY) {
d8ed45c5 1427 mmap_read_lock(mm);
475f4dfc
PX
1428 *unlocked = true;
1429 fault_flags |= FAULT_FLAG_TRIED;
1430 goto retry;
4a9e1cda
DD
1431 }
1432
4bbd4c77
KS
1433 return 0;
1434}
add6a0cd 1435EXPORT_SYMBOL_GPL(fixup_user_fault);
4bbd4c77 1436
93c5c61d
PX
1437/*
1438 * GUP always responds to fatal signals. When FOLL_INTERRUPTIBLE is
1439 * specified, it'll also respond to generic signals. The caller of GUP
1440 * that has FOLL_INTERRUPTIBLE should take care of the GUP interruption.
1441 */
1442static bool gup_signal_pending(unsigned int flags)
1443{
1444 if (fatal_signal_pending(current))
1445 return true;
1446
1447 if (!(flags & FOLL_INTERRUPTIBLE))
1448 return false;
1449
1450 return signal_pending(current);
1451}
1452
2d3a36a4 1453/*
b2a72dff
JG
1454 * Locking: (*locked == 1) means that the mmap_lock has already been acquired by
1455 * the caller. This function may drop the mmap_lock. If it does so, then it will
1456 * set (*locked = 0).
1457 *
1458 * (*locked == 0) means that the caller expects this function to acquire and
1459 * drop the mmap_lock. Therefore, the value of *locked will still be zero when
1460 * the function returns, even though it may have changed temporarily during
1461 * function execution.
1462 *
1463 * Please note that this function, unlike __get_user_pages(), will not return 0
1464 * for nr_pages > 0, unless FOLL_NOWAIT is used.
2d3a36a4 1465 */
64019a2e 1466static __always_inline long __get_user_pages_locked(struct mm_struct *mm,
f0818f47
AA
1467 unsigned long start,
1468 unsigned long nr_pages,
f0818f47 1469 struct page **pages,
e716712f 1470 int *locked,
0fd71a56 1471 unsigned int flags)
f0818f47 1472{
f0818f47 1473 long ret, pages_done;
b2a72dff 1474 bool must_unlock = false;
f0818f47 1475
9c4b2142
LS
1476 if (!nr_pages)
1477 return 0;
1478
b2a72dff
JG
1479 /*
1480 * The internal caller expects GUP to manage the lock internally and the
1481 * lock must be released when this returns.
1482 */
9a863a6a 1483 if (!*locked) {
b2a72dff
JG
1484 if (mmap_read_lock_killable(mm))
1485 return -EAGAIN;
1486 must_unlock = true;
1487 *locked = 1;
f0818f47 1488 }
961ba472
JG
1489 else
1490 mmap_assert_locked(mm);
f0818f47 1491
a458b76a
AA
1492 if (flags & FOLL_PIN)
1493 mm_set_has_pinned_flag(&mm->flags);
008cfe44 1494
eddb1c22
JH
1495 /*
1496 * FOLL_PIN and FOLL_GET are mutually exclusive. Traditional behavior
1497 * is to set FOLL_GET if the caller wants pages[] filled in (but has
1498 * carelessly failed to specify FOLL_GET), so keep doing that, but only
1499 * for FOLL_GET, not for the newer FOLL_PIN.
1500 *
1501 * FOLL_PIN always expects pages to be non-null, but no need to assert
1502 * that here, as any failures will be obvious enough.
1503 */
1504 if (pages && !(flags & FOLL_PIN))
f0818f47 1505 flags |= FOLL_GET;
f0818f47
AA
1506
1507 pages_done = 0;
f0818f47 1508 for (;;) {
64019a2e 1509 ret = __get_user_pages(mm, start, nr_pages, flags, pages,
b2cac248 1510 locked);
f04740f5 1511 if (!(flags & FOLL_UNLOCKABLE)) {
f0818f47 1512 /* VM_FAULT_RETRY couldn't trigger, bypass */
f04740f5
JG
1513 pages_done = ret;
1514 break;
1515 }
f0818f47 1516
d9272525 1517 /* VM_FAULT_RETRY or VM_FAULT_COMPLETED cannot return errors */
f0818f47
AA
1518 if (!*locked) {
1519 BUG_ON(ret < 0);
1520 BUG_ON(ret >= nr_pages);
1521 }
1522
f0818f47
AA
1523 if (ret > 0) {
1524 nr_pages -= ret;
1525 pages_done += ret;
1526 if (!nr_pages)
1527 break;
1528 }
1529 if (*locked) {
96312e61
AA
1530 /*
1531 * VM_FAULT_RETRY didn't trigger or it was a
1532 * FOLL_NOWAIT.
1533 */
f0818f47
AA
1534 if (!pages_done)
1535 pages_done = ret;
1536 break;
1537 }
df17277b
MR
1538 /*
1539 * VM_FAULT_RETRY triggered, so seek to the faulting offset.
1540 * For the prefault case (!pages) we only update counts.
1541 */
1542 if (likely(pages))
1543 pages += ret;
f0818f47 1544 start += ret << PAGE_SHIFT;
b2a72dff
JG
1545
1546 /* The lock was temporarily dropped, so we must unlock later */
1547 must_unlock = true;
f0818f47 1548
4426e945 1549retry:
f0818f47
AA
1550 /*
1551 * Repeat on the address that fired VM_FAULT_RETRY
4426e945
PX
1552 * with both FAULT_FLAG_ALLOW_RETRY and
1553 * FAULT_FLAG_TRIED. Note that GUP can be interrupted
93c5c61d
PX
1554 * by fatal signals of even common signals, depending on
1555 * the caller's request. So we need to check it before we
4426e945 1556 * start trying again otherwise it can loop forever.
f0818f47 1557 */
93c5c61d 1558 if (gup_signal_pending(flags)) {
ae46d2aa
HD
1559 if (!pages_done)
1560 pages_done = -EINTR;
4426e945 1561 break;
ae46d2aa 1562 }
4426e945 1563
d8ed45c5 1564 ret = mmap_read_lock_killable(mm);
71335f37
PX
1565 if (ret) {
1566 BUG_ON(ret > 0);
1567 if (!pages_done)
1568 pages_done = ret;
1569 break;
1570 }
4426e945 1571
c7b6a566 1572 *locked = 1;
64019a2e 1573 ret = __get_user_pages(mm, start, 1, flags | FOLL_TRIED,
b2cac248 1574 pages, locked);
4426e945
PX
1575 if (!*locked) {
1576 /* Continue to retry until we succeeded */
1577 BUG_ON(ret != 0);
1578 goto retry;
1579 }
f0818f47
AA
1580 if (ret != 1) {
1581 BUG_ON(ret > 1);
1582 if (!pages_done)
1583 pages_done = ret;
1584 break;
1585 }
1586 nr_pages--;
1587 pages_done++;
1588 if (!nr_pages)
1589 break;
df17277b
MR
1590 if (likely(pages))
1591 pages++;
f0818f47
AA
1592 start += PAGE_SIZE;
1593 }
b2a72dff 1594 if (must_unlock && *locked) {
f0818f47 1595 /*
b2a72dff
JG
1596 * We either temporarily dropped the lock, or the caller
1597 * requested that we both acquire and drop the lock. Either way,
1598 * we must now unlock, and notify the caller of that state.
f0818f47 1599 */
d8ed45c5 1600 mmap_read_unlock(mm);
f0818f47
AA
1601 *locked = 0;
1602 }
9c4b2142
LS
1603
1604 /*
1605 * Failing to pin anything implies something has gone wrong (except when
1606 * FOLL_NOWAIT is specified).
1607 */
1608 if (WARN_ON_ONCE(pages_done == 0 && !(flags & FOLL_NOWAIT)))
1609 return -EFAULT;
1610
f0818f47
AA
1611 return pages_done;
1612}
1613
d3649f68
CH
1614/**
1615 * populate_vma_page_range() - populate a range of pages in the vma.
1616 * @vma: target vma
1617 * @start: start address
1618 * @end: end address
c1e8d7c6 1619 * @locked: whether the mmap_lock is still held
d3649f68
CH
1620 *
1621 * This takes care of mlocking the pages too if VM_LOCKED is set.
1622 *
0a36f7f8
TY
1623 * Return either number of pages pinned in the vma, or a negative error
1624 * code on error.
d3649f68 1625 *
c1e8d7c6 1626 * vma->vm_mm->mmap_lock must be held.
d3649f68 1627 *
4f6da934 1628 * If @locked is NULL, it may be held for read or write and will
d3649f68
CH
1629 * be unperturbed.
1630 *
4f6da934
PX
1631 * If @locked is non-NULL, it must held for read only and may be
1632 * released. If it's released, *@locked will be set to 0.
d3649f68
CH
1633 */
1634long populate_vma_page_range(struct vm_area_struct *vma,
4f6da934 1635 unsigned long start, unsigned long end, int *locked)
d3649f68
CH
1636{
1637 struct mm_struct *mm = vma->vm_mm;
1638 unsigned long nr_pages = (end - start) / PAGE_SIZE;
9a863a6a 1639 int local_locked = 1;
d3649f68 1640 int gup_flags;
ece369c7 1641 long ret;
d3649f68 1642
be51eb18
ML
1643 VM_BUG_ON(!PAGE_ALIGNED(start));
1644 VM_BUG_ON(!PAGE_ALIGNED(end));
d3649f68
CH
1645 VM_BUG_ON_VMA(start < vma->vm_start, vma);
1646 VM_BUG_ON_VMA(end > vma->vm_end, vma);
42fc5414 1647 mmap_assert_locked(mm);
d3649f68 1648
b67bf49c
HD
1649 /*
1650 * Rightly or wrongly, the VM_LOCKONFAULT case has never used
1651 * faultin_page() to break COW, so it has no work to do here.
1652 */
d3649f68 1653 if (vma->vm_flags & VM_LOCKONFAULT)
b67bf49c
HD
1654 return nr_pages;
1655
1096bc93
LT
1656 /* ... similarly, we've never faulted in PROT_NONE pages */
1657 if (!vma_is_accessible(vma))
1658 return -EFAULT;
1659
b67bf49c 1660 gup_flags = FOLL_TOUCH;
d3649f68
CH
1661 /*
1662 * We want to touch writable mappings with a write fault in order
1663 * to break COW, except for shared mappings because these don't COW
1664 * and we would not want to dirty them for nothing.
1096bc93
LT
1665 *
1666 * Otherwise, do a read fault, and use FOLL_FORCE in case it's not
1667 * readable (ie write-only or executable).
d3649f68
CH
1668 */
1669 if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
1670 gup_flags |= FOLL_WRITE;
1096bc93 1671 else
d3649f68
CH
1672 gup_flags |= FOLL_FORCE;
1673
f04740f5
JG
1674 if (locked)
1675 gup_flags |= FOLL_UNLOCKABLE;
1676
d3649f68
CH
1677 /*
1678 * We made sure addr is within a VMA, so the following will
1679 * not result in a stack expansion that recurses back here.
1680 */
ece369c7 1681 ret = __get_user_pages(mm, start, nr_pages, gup_flags,
b2cac248 1682 NULL, locked ? locked : &local_locked);
ece369c7
HD
1683 lru_add_drain();
1684 return ret;
d3649f68
CH
1685}
1686
4ca9b385
DH
1687/*
1688 * faultin_vma_page_range() - populate (prefault) page tables inside the
1689 * given VMA range readable/writable
1690 *
1691 * This takes care of mlocking the pages, too, if VM_LOCKED is set.
1692 *
1693 * @vma: target vma
1694 * @start: start address
1695 * @end: end address
1696 * @write: whether to prefault readable or writable
1697 * @locked: whether the mmap_lock is still held
1698 *
1699 * Returns either number of processed pages in the vma, or a negative error
1700 * code on error (see __get_user_pages()).
1701 *
1702 * vma->vm_mm->mmap_lock must be held. The range must be page-aligned and
6e4382c7 1703 * covered by the VMA. If it's released, *@locked will be set to 0.
4ca9b385
DH
1704 */
1705long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
1706 unsigned long end, bool write, int *locked)
1707{
1708 struct mm_struct *mm = vma->vm_mm;
1709 unsigned long nr_pages = (end - start) / PAGE_SIZE;
1710 int gup_flags;
ece369c7 1711 long ret;
4ca9b385
DH
1712
1713 VM_BUG_ON(!PAGE_ALIGNED(start));
1714 VM_BUG_ON(!PAGE_ALIGNED(end));
1715 VM_BUG_ON_VMA(start < vma->vm_start, vma);
1716 VM_BUG_ON_VMA(end > vma->vm_end, vma);
1717 mmap_assert_locked(mm);
1718
1719 /*
1720 * FOLL_TOUCH: Mark page accessed and thereby young; will also mark
1721 * the page dirty with FOLL_WRITE -- which doesn't make a
1722 * difference with !FOLL_FORCE, because the page is writable
1723 * in the page table.
1724 * FOLL_HWPOISON: Return -EHWPOISON instead of -EFAULT when we hit
1725 * a poisoned page.
4ca9b385
DH
1726 * !FOLL_FORCE: Require proper access permissions.
1727 */
f04740f5 1728 gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE;
4ca9b385
DH
1729 if (write)
1730 gup_flags |= FOLL_WRITE;
1731
1732 /*
eb2faa51
DH
1733 * We want to report -EINVAL instead of -EFAULT for any permission
1734 * problems or incompatible mappings.
4ca9b385 1735 */
eb2faa51
DH
1736 if (check_vma_flags(vma, gup_flags))
1737 return -EINVAL;
1738
ece369c7 1739 ret = __get_user_pages(mm, start, nr_pages, gup_flags,
b2cac248 1740 NULL, locked);
ece369c7
HD
1741 lru_add_drain();
1742 return ret;
4ca9b385
DH
1743}
1744
d3649f68
CH
1745/*
1746 * __mm_populate - populate and/or mlock pages within a range of address space.
1747 *
1748 * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
1749 * flags. VMAs must be already marked with the desired vm_flags, and
c1e8d7c6 1750 * mmap_lock must not be held.
d3649f68
CH
1751 */
1752int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
1753{
1754 struct mm_struct *mm = current->mm;
1755 unsigned long end, nstart, nend;
1756 struct vm_area_struct *vma = NULL;
1757 int locked = 0;
1758 long ret = 0;
1759
1760 end = start + len;
1761
1762 for (nstart = start; nstart < end; nstart = nend) {
1763 /*
1764 * We want to fault in pages for [nstart; end) address range.
1765 * Find first corresponding VMA.
1766 */
1767 if (!locked) {
1768 locked = 1;
d8ed45c5 1769 mmap_read_lock(mm);
c4d1a92d 1770 vma = find_vma_intersection(mm, nstart, end);
d3649f68 1771 } else if (nstart >= vma->vm_end)
c4d1a92d
LH
1772 vma = find_vma_intersection(mm, vma->vm_end, end);
1773
1774 if (!vma)
d3649f68
CH
1775 break;
1776 /*
1777 * Set [nstart; nend) to intersection of desired address
1778 * range with the first VMA. Also, skip undesirable VMA types.
1779 */
1780 nend = min(end, vma->vm_end);
1781 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
1782 continue;
1783 if (nstart < vma->vm_start)
1784 nstart = vma->vm_start;
1785 /*
1786 * Now fault in a range of pages. populate_vma_page_range()
1787 * double checks the vma flags, so that it won't mlock pages
1788 * if the vma was already munlocked.
1789 */
1790 ret = populate_vma_page_range(vma, nstart, nend, &locked);
1791 if (ret < 0) {
1792 if (ignore_errors) {
1793 ret = 0;
1794 continue; /* continue at next VMA */
1795 }
1796 break;
1797 }
1798 nend = nstart + ret * PAGE_SIZE;
1799 ret = 0;
1800 }
1801 if (locked)
d8ed45c5 1802 mmap_read_unlock(mm);
d3649f68
CH
1803 return ret; /* 0 or negative error code */
1804}
050a9adc 1805#else /* CONFIG_MMU */
64019a2e 1806static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
050a9adc 1807 unsigned long nr_pages, struct page **pages,
b2cac248 1808 int *locked, unsigned int foll_flags)
050a9adc
CH
1809{
1810 struct vm_area_struct *vma;
b2a72dff 1811 bool must_unlock = false;
050a9adc 1812 unsigned long vm_flags;
24dc20c7 1813 long i;
050a9adc 1814
b2a72dff
JG
1815 if (!nr_pages)
1816 return 0;
1817
1818 /*
1819 * The internal caller expects GUP to manage the lock internally and the
1820 * lock must be released when this returns.
1821 */
9a863a6a 1822 if (!*locked) {
b2a72dff
JG
1823 if (mmap_read_lock_killable(mm))
1824 return -EAGAIN;
1825 must_unlock = true;
1826 *locked = 1;
1827 }
1828
050a9adc
CH
1829 /* calculate required read or write permissions.
1830 * If FOLL_FORCE is set, we only require the "MAY" flags.
1831 */
1832 vm_flags = (foll_flags & FOLL_WRITE) ?
1833 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1834 vm_flags &= (foll_flags & FOLL_FORCE) ?
1835 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1836
1837 for (i = 0; i < nr_pages; i++) {
1838 vma = find_vma(mm, start);
1839 if (!vma)
b2a72dff 1840 break;
050a9adc
CH
1841
1842 /* protect what we can, including chardevs */
1843 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1844 !(vm_flags & vma->vm_flags))
b2a72dff 1845 break;
050a9adc
CH
1846
1847 if (pages) {
396a400b 1848 pages[i] = virt_to_page((void *)start);
050a9adc
CH
1849 if (pages[i])
1850 get_page(pages[i]);
1851 }
b2cac248 1852
050a9adc
CH
1853 start = (start + PAGE_SIZE) & PAGE_MASK;
1854 }
1855
b2a72dff
JG
1856 if (must_unlock && *locked) {
1857 mmap_read_unlock(mm);
1858 *locked = 0;
1859 }
050a9adc 1860
050a9adc
CH
1861 return i ? : -EFAULT;
1862}
1863#endif /* !CONFIG_MMU */
d3649f68 1864
bb523b40
AG
1865/**
1866 * fault_in_writeable - fault in userspace address range for writing
1867 * @uaddr: start of address range
1868 * @size: size of address range
1869 *
1870 * Returns the number of bytes not faulted in (like copy_to_user() and
1871 * copy_from_user()).
1872 */
1873size_t fault_in_writeable(char __user *uaddr, size_t size)
1874{
1875 char __user *start = uaddr, *end;
1876
1877 if (unlikely(size == 0))
1878 return 0;
677b2a8c
CL
1879 if (!user_write_access_begin(uaddr, size))
1880 return size;
bb523b40 1881 if (!PAGE_ALIGNED(uaddr)) {
677b2a8c 1882 unsafe_put_user(0, uaddr, out);
bb523b40
AG
1883 uaddr = (char __user *)PAGE_ALIGN((unsigned long)uaddr);
1884 }
1885 end = (char __user *)PAGE_ALIGN((unsigned long)start + size);
1886 if (unlikely(end < start))
1887 end = NULL;
1888 while (uaddr != end) {
677b2a8c 1889 unsafe_put_user(0, uaddr, out);
bb523b40
AG
1890 uaddr += PAGE_SIZE;
1891 }
1892
1893out:
677b2a8c 1894 user_write_access_end();
bb523b40
AG
1895 if (size > uaddr - start)
1896 return size - (uaddr - start);
1897 return 0;
1898}
1899EXPORT_SYMBOL(fault_in_writeable);
1900
da32b581
CM
1901/**
1902 * fault_in_subpage_writeable - fault in an address range for writing
1903 * @uaddr: start of address range
1904 * @size: size of address range
1905 *
1906 * Fault in a user address range for writing while checking for permissions at
1907 * sub-page granularity (e.g. arm64 MTE). This function should be used when
1908 * the caller cannot guarantee forward progress of a copy_to_user() loop.
1909 *
1910 * Returns the number of bytes not faulted in (like copy_to_user() and
1911 * copy_from_user()).
1912 */
1913size_t fault_in_subpage_writeable(char __user *uaddr, size_t size)
1914{
1915 size_t faulted_in;
1916
1917 /*
1918 * Attempt faulting in at page granularity first for page table
1919 * permission checking. The arch-specific probe_subpage_writeable()
1920 * functions may not check for this.
1921 */
1922 faulted_in = size - fault_in_writeable(uaddr, size);
1923 if (faulted_in)
1924 faulted_in -= probe_subpage_writeable(uaddr, faulted_in);
1925
1926 return size - faulted_in;
1927}
1928EXPORT_SYMBOL(fault_in_subpage_writeable);
1929
cdd591fc
AG
1930/*
1931 * fault_in_safe_writeable - fault in an address range for writing
1932 * @uaddr: start of address range
1933 * @size: length of address range
1934 *
fe673d3f
LT
1935 * Faults in an address range for writing. This is primarily useful when we
1936 * already know that some or all of the pages in the address range aren't in
1937 * memory.
cdd591fc 1938 *
fe673d3f 1939 * Unlike fault_in_writeable(), this function is non-destructive.
cdd591fc
AG
1940 *
1941 * Note that we don't pin or otherwise hold the pages referenced that we fault
1942 * in. There's no guarantee that they'll stay in memory for any duration of
1943 * time.
1944 *
1945 * Returns the number of bytes not faulted in, like copy_to_user() and
1946 * copy_from_user().
1947 */
1948size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
1949{
fe673d3f 1950 unsigned long start = (unsigned long)uaddr, end;
cdd591fc 1951 struct mm_struct *mm = current->mm;
fe673d3f 1952 bool unlocked = false;
cdd591fc 1953
fe673d3f
LT
1954 if (unlikely(size == 0))
1955 return 0;
cdd591fc 1956 end = PAGE_ALIGN(start + size);
fe673d3f 1957 if (end < start)
cdd591fc 1958 end = 0;
cdd591fc 1959
fe673d3f
LT
1960 mmap_read_lock(mm);
1961 do {
1962 if (fixup_user_fault(mm, start, FAULT_FLAG_WRITE, &unlocked))
cdd591fc 1963 break;
fe673d3f
LT
1964 start = (start + PAGE_SIZE) & PAGE_MASK;
1965 } while (start != end);
1966 mmap_read_unlock(mm);
1967
1968 if (size > (unsigned long)uaddr - start)
1969 return size - ((unsigned long)uaddr - start);
1970 return 0;
cdd591fc
AG
1971}
1972EXPORT_SYMBOL(fault_in_safe_writeable);
1973
bb523b40
AG
1974/**
1975 * fault_in_readable - fault in userspace address range for reading
1976 * @uaddr: start of user address range
1977 * @size: size of user address range
1978 *
1979 * Returns the number of bytes not faulted in (like copy_to_user() and
1980 * copy_from_user()).
1981 */
1982size_t fault_in_readable(const char __user *uaddr, size_t size)
1983{
1984 const char __user *start = uaddr, *end;
1985 volatile char c;
1986
1987 if (unlikely(size == 0))
1988 return 0;
677b2a8c
CL
1989 if (!user_read_access_begin(uaddr, size))
1990 return size;
bb523b40 1991 if (!PAGE_ALIGNED(uaddr)) {
677b2a8c 1992 unsafe_get_user(c, uaddr, out);
bb523b40
AG
1993 uaddr = (const char __user *)PAGE_ALIGN((unsigned long)uaddr);
1994 }
1995 end = (const char __user *)PAGE_ALIGN((unsigned long)start + size);
1996 if (unlikely(end < start))
1997 end = NULL;
1998 while (uaddr != end) {
677b2a8c 1999 unsafe_get_user(c, uaddr, out);
bb523b40
AG
2000 uaddr += PAGE_SIZE;
2001 }
2002
2003out:
677b2a8c 2004 user_read_access_end();
bb523b40
AG
2005 (void)c;
2006 if (size > uaddr - start)
2007 return size - (uaddr - start);
2008 return 0;
2009}
2010EXPORT_SYMBOL(fault_in_readable);
2011
8f942eea
JH
2012/**
2013 * get_dump_page() - pin user page in memory while writing it to core dump
2014 * @addr: user address
2015 *
2016 * Returns struct page pointer of user page pinned for dump,
2017 * to be freed afterwards by put_page().
2018 *
2019 * Returns NULL on any kind of failure - a hole must then be inserted into
2020 * the corefile, to preserve alignment with its headers; and also returns
2021 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
f0953a1b 2022 * allowing a hole to be left in the corefile to save disk space.
8f942eea 2023 *
7f3bfab5 2024 * Called without mmap_lock (takes and releases the mmap_lock by itself).
8f942eea
JH
2025 */
2026#ifdef CONFIG_ELF_CORE
2027struct page *get_dump_page(unsigned long addr)
2028{
8f942eea 2029 struct page *page;
b2a72dff 2030 int locked = 0;
7f3bfab5 2031 int ret;
8f942eea 2032
b2cac248 2033 ret = __get_user_pages_locked(current->mm, addr, 1, &page, &locked,
7f3bfab5 2034 FOLL_FORCE | FOLL_DUMP | FOLL_GET);
7f3bfab5 2035 return (ret == 1) ? page : NULL;
8f942eea
JH
2036}
2037#endif /* CONFIG_ELF_CORE */
2038
d1e153fe 2039#ifdef CONFIG_MIGRATION
f68749ec 2040/*
67e139b0 2041 * Returns the number of collected pages. Return value is always >= 0.
f68749ec 2042 */
67e139b0
AP
2043static unsigned long collect_longterm_unpinnable_pages(
2044 struct list_head *movable_page_list,
2045 unsigned long nr_pages,
2046 struct page **pages)
9a4e9f3b 2047{
67e139b0 2048 unsigned long i, collected = 0;
1b7f7e58 2049 struct folio *prev_folio = NULL;
67e139b0 2050 bool drain_allow = true;
9a4e9f3b 2051
83c02c23 2052 for (i = 0; i < nr_pages; i++) {
1b7f7e58 2053 struct folio *folio = page_folio(pages[i]);
f9f38f78 2054
1b7f7e58 2055 if (folio == prev_folio)
83c02c23 2056 continue;
1b7f7e58 2057 prev_folio = folio;
f9f38f78 2058
67e139b0
AP
2059 if (folio_is_longterm_pinnable(folio))
2060 continue;
b05a79d4 2061
67e139b0 2062 collected++;
b05a79d4 2063
67e139b0 2064 if (folio_is_device_coherent(folio))
f9f38f78
CH
2065 continue;
2066
1b7f7e58 2067 if (folio_test_hugetlb(folio)) {
6aa3a920 2068 isolate_hugetlb(folio, movable_page_list);
f9f38f78
CH
2069 continue;
2070 }
9a4e9f3b 2071
1b7f7e58 2072 if (!folio_test_lru(folio) && drain_allow) {
f9f38f78
CH
2073 lru_add_drain_all();
2074 drain_allow = false;
2075 }
2076
be2d5756 2077 if (!folio_isolate_lru(folio))
f9f38f78 2078 continue;
67e139b0
AP
2079
2080 list_add_tail(&folio->lru, movable_page_list);
1b7f7e58
MWO
2081 node_stat_mod_folio(folio,
2082 NR_ISOLATED_ANON + folio_is_file_lru(folio),
2083 folio_nr_pages(folio));
9a4e9f3b
AK
2084 }
2085
67e139b0
AP
2086 return collected;
2087}
2088
2089/*
2090 * Unpins all pages and migrates device coherent pages and movable_page_list.
2091 * Returns -EAGAIN if all pages were successfully migrated or -errno for failure
2092 * (or partial success).
2093 */
2094static int migrate_longterm_unpinnable_pages(
2095 struct list_head *movable_page_list,
2096 unsigned long nr_pages,
2097 struct page **pages)
2098{
2099 int ret;
2100 unsigned long i;
6e7f34eb 2101
b05a79d4 2102 for (i = 0; i < nr_pages; i++) {
67e139b0
AP
2103 struct folio *folio = page_folio(pages[i]);
2104
2105 if (folio_is_device_coherent(folio)) {
2106 /*
2107 * Migration will fail if the page is pinned, so convert
2108 * the pin on the source page to a normal reference.
2109 */
2110 pages[i] = NULL;
2111 folio_get(folio);
2112 gup_put_folio(folio, 1, FOLL_PIN);
2113
2114 if (migrate_device_coherent_page(&folio->page)) {
2115 ret = -EBUSY;
2116 goto err;
2117 }
2118
b05a79d4 2119 continue;
67e139b0 2120 }
b05a79d4 2121
67e139b0
AP
2122 /*
2123 * We can't migrate pages with unexpected references, so drop
2124 * the reference obtained by __get_user_pages_locked().
2125 * Migrating pages have been added to movable_page_list after
2126 * calling folio_isolate_lru() which takes a reference so the
2127 * page won't be freed if it's migrating.
2128 */
f6d299ec 2129 unpin_user_page(pages[i]);
67e139b0 2130 pages[i] = NULL;
f68749ec 2131 }
f9f38f78 2132
67e139b0 2133 if (!list_empty(movable_page_list)) {
f9f38f78
CH
2134 struct migration_target_control mtc = {
2135 .nid = NUMA_NO_NODE,
2136 .gfp_mask = GFP_USER | __GFP_NOWARN,
2137 };
2138
67e139b0
AP
2139 if (migrate_pages(movable_page_list, alloc_migration_target,
2140 NULL, (unsigned long)&mtc, MIGRATE_SYNC,
2141 MR_LONGTERM_PIN, NULL)) {
f9f38f78 2142 ret = -ENOMEM;
67e139b0
AP
2143 goto err;
2144 }
9a4e9f3b
AK
2145 }
2146
67e139b0
AP
2147 putback_movable_pages(movable_page_list);
2148
2149 return -EAGAIN;
2150
2151err:
2152 for (i = 0; i < nr_pages; i++)
2153 if (pages[i])
2154 unpin_user_page(pages[i]);
2155 putback_movable_pages(movable_page_list);
24a95998 2156
67e139b0
AP
2157 return ret;
2158}
2159
2160/*
2161 * Check whether all pages are *allowed* to be pinned. Rather confusingly, all
2162 * pages in the range are required to be pinned via FOLL_PIN, before calling
2163 * this routine.
2164 *
2165 * If any pages in the range are not allowed to be pinned, then this routine
2166 * will migrate those pages away, unpin all the pages in the range and return
2167 * -EAGAIN. The caller should re-pin the entire range with FOLL_PIN and then
2168 * call this routine again.
2169 *
2170 * If an error other than -EAGAIN occurs, this indicates a migration failure.
2171 * The caller should give up, and propagate the error back up the call stack.
2172 *
2173 * If everything is OK and all pages in the range are allowed to be pinned, then
2174 * this routine leaves all pages pinned and returns zero for success.
2175 */
2176static long check_and_migrate_movable_pages(unsigned long nr_pages,
2177 struct page **pages)
2178{
2179 unsigned long collected;
2180 LIST_HEAD(movable_page_list);
2181
2182 collected = collect_longterm_unpinnable_pages(&movable_page_list,
2183 nr_pages, pages);
2184 if (!collected)
2185 return 0;
2186
2187 return migrate_longterm_unpinnable_pages(&movable_page_list, nr_pages,
2188 pages);
9a4e9f3b
AK
2189}
2190#else
f68749ec 2191static long check_and_migrate_movable_pages(unsigned long nr_pages,
f6d299ec 2192 struct page **pages)
9a4e9f3b 2193{
24a95998 2194 return 0;
9a4e9f3b 2195}
d1e153fe 2196#endif /* CONFIG_MIGRATION */
9a4e9f3b 2197
2bb6d283 2198/*
932f4a63
IW
2199 * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
2200 * allows us to process the FOLL_LONGTERM flag.
2bb6d283 2201 */
64019a2e 2202static long __gup_longterm_locked(struct mm_struct *mm,
932f4a63
IW
2203 unsigned long start,
2204 unsigned long nr_pages,
2205 struct page **pages,
53b2d09b 2206 int *locked,
932f4a63 2207 unsigned int gup_flags)
2bb6d283 2208{
f68749ec 2209 unsigned int flags;
24a95998 2210 long rc, nr_pinned_pages;
2bb6d283 2211
f68749ec 2212 if (!(gup_flags & FOLL_LONGTERM))
b2cac248 2213 return __get_user_pages_locked(mm, start, nr_pages, pages,
53b2d09b 2214 locked, gup_flags);
67e139b0 2215
f68749ec
PT
2216 flags = memalloc_pin_save();
2217 do {
24a95998 2218 nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages,
b2cac248 2219 pages, locked,
24a95998
AP
2220 gup_flags);
2221 if (nr_pinned_pages <= 0) {
2222 rc = nr_pinned_pages;
f68749ec 2223 break;
24a95998 2224 }
d64e2dbc
JG
2225
2226 /* FOLL_LONGTERM implies FOLL_PIN */
f6d299ec 2227 rc = check_and_migrate_movable_pages(nr_pinned_pages, pages);
24a95998 2228 } while (rc == -EAGAIN);
f68749ec 2229 memalloc_pin_restore(flags);
24a95998 2230 return rc ? rc : nr_pinned_pages;
2bb6d283 2231}
932f4a63 2232
d64e2dbc
JG
2233/*
2234 * Check that the given flags are valid for the exported gup/pup interface, and
2235 * update them with the required flags that the caller must have set.
2236 */
b2cac248
LS
2237static bool is_valid_gup_args(struct page **pages, int *locked,
2238 unsigned int *gup_flags_p, unsigned int to_set)
447f3e45 2239{
d64e2dbc
JG
2240 unsigned int gup_flags = *gup_flags_p;
2241
447f3e45 2242 /*
d64e2dbc
JG
2243 * These flags not allowed to be specified externally to the gup
2244 * interfaces:
0f20bba1 2245 * - FOLL_TOUCH/FOLL_PIN/FOLL_TRIED/FOLL_FAST_ONLY are internal only
d64e2dbc 2246 * - FOLL_REMOTE is internal only and used on follow_page()
f04740f5 2247 * - FOLL_UNLOCKABLE is internal only and used if locked is !NULL
447f3e45 2248 */
0f20bba1 2249 if (WARN_ON_ONCE(gup_flags & INTERNAL_GUP_FLAGS))
d64e2dbc
JG
2250 return false;
2251
2252 gup_flags |= to_set;
f04740f5
JG
2253 if (locked) {
2254 /* At the external interface locked must be set */
2255 if (WARN_ON_ONCE(*locked != 1))
2256 return false;
2257
2258 gup_flags |= FOLL_UNLOCKABLE;
2259 }
d64e2dbc
JG
2260
2261 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
2262 if (WARN_ON_ONCE((gup_flags & (FOLL_PIN | FOLL_GET)) ==
2263 (FOLL_PIN | FOLL_GET)))
2264 return false;
2265
2266 /* LONGTERM can only be specified when pinning */
2267 if (WARN_ON_ONCE(!(gup_flags & FOLL_PIN) && (gup_flags & FOLL_LONGTERM)))
2268 return false;
2269
2270 /* Pages input must be given if using GET/PIN */
2271 if (WARN_ON_ONCE((gup_flags & (FOLL_GET | FOLL_PIN)) && !pages))
447f3e45 2272 return false;
d64e2dbc 2273
d64e2dbc
JG
2274 /* We want to allow the pgmap to be hot-unplugged at all times */
2275 if (WARN_ON_ONCE((gup_flags & FOLL_LONGTERM) &&
2276 (gup_flags & FOLL_PCI_P2PDMA)))
2277 return false;
2278
d64e2dbc 2279 *gup_flags_p = gup_flags;
447f3e45
BS
2280 return true;
2281}
2282
22bf29b6 2283#ifdef CONFIG_MMU
adc8cb40 2284/**
c4237f8b 2285 * get_user_pages_remote() - pin user pages in memory
c4237f8b
JH
2286 * @mm: mm_struct of target mm
2287 * @start: starting user address
2288 * @nr_pages: number of pages from start to pin
2289 * @gup_flags: flags modifying lookup behaviour
2290 * @pages: array that receives pointers to the pages pinned.
2291 * Should be at least nr_pages long. Or NULL, if caller
2292 * only intends to ensure the pages are faulted in.
c4237f8b
JH
2293 * @locked: pointer to lock flag indicating whether lock is held and
2294 * subsequently whether VM_FAULT_RETRY functionality can be
2295 * utilised. Lock must initially be held.
2296 *
2297 * Returns either number of pages pinned (which may be less than the
2298 * number requested), or an error. Details about the return value:
2299 *
2300 * -- If nr_pages is 0, returns 0.
2301 * -- If nr_pages is >0, but no pages were pinned, returns -errno.
2302 * -- If nr_pages is >0, and some pages were pinned, returns the number of
2303 * pages pinned. Again, this may be less than nr_pages.
2304 *
2305 * The caller is responsible for releasing returned @pages, via put_page().
2306 *
c1e8d7c6 2307 * Must be called with mmap_lock held for read or write.
c4237f8b 2308 *
adc8cb40
SJ
2309 * get_user_pages_remote walks a process's page tables and takes a reference
2310 * to each struct page that each user address corresponds to at a given
c4237f8b
JH
2311 * instant. That is, it takes the page that would be accessed if a user
2312 * thread accesses the given user virtual address at that instant.
2313 *
2314 * This does not guarantee that the page exists in the user mappings when
adc8cb40 2315 * get_user_pages_remote returns, and there may even be a completely different
c4237f8b 2316 * page there in some cases (eg. if mmapped pagecache has been invalidated
5da1a868 2317 * and subsequently re-faulted). However it does guarantee that the page
c4237f8b
JH
2318 * won't be freed completely. And mostly callers simply care that the page
2319 * contains data that was valid *at some point in time*. Typically, an IO
2320 * or similar operation cannot guarantee anything stronger anyway because
2321 * locks can't be held over the syscall boundary.
2322 *
2323 * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page
2324 * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must
2325 * be called after the page is finished with, and before put_page is called.
2326 *
adc8cb40
SJ
2327 * get_user_pages_remote is typically used for fewer-copy IO operations,
2328 * to get a handle on the memory by some means other than accesses
2329 * via the user virtual addresses. The pages may be submitted for
2330 * DMA to devices or accessed via their kernel linear mapping (via the
2331 * kmap APIs). Care should be taken to use the correct cache flushing APIs.
c4237f8b
JH
2332 *
2333 * See also get_user_pages_fast, for performance critical applications.
2334 *
adc8cb40 2335 * get_user_pages_remote should be phased out in favor of
c4237f8b 2336 * get_user_pages_locked|unlocked or get_user_pages_fast. Nothing
adc8cb40 2337 * should use get_user_pages_remote because it cannot pass
c4237f8b
JH
2338 * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
2339 */
64019a2e 2340long get_user_pages_remote(struct mm_struct *mm,
c4237f8b
JH
2341 unsigned long start, unsigned long nr_pages,
2342 unsigned int gup_flags, struct page **pages,
ca5e8632 2343 int *locked)
c4237f8b 2344{
9a863a6a
JG
2345 int local_locked = 1;
2346
b2cac248 2347 if (!is_valid_gup_args(pages, locked, &gup_flags,
d64e2dbc 2348 FOLL_TOUCH | FOLL_REMOTE))
eddb1c22
JH
2349 return -EINVAL;
2350
b2cac248 2351 return __get_user_pages_locked(mm, start, nr_pages, pages,
9a863a6a 2352 locked ? locked : &local_locked,
d64e2dbc 2353 gup_flags);
c4237f8b
JH
2354}
2355EXPORT_SYMBOL(get_user_pages_remote);
2356
eddb1c22 2357#else /* CONFIG_MMU */
64019a2e 2358long get_user_pages_remote(struct mm_struct *mm,
eddb1c22
JH
2359 unsigned long start, unsigned long nr_pages,
2360 unsigned int gup_flags, struct page **pages,
ca5e8632 2361 int *locked)
eddb1c22
JH
2362{
2363 return 0;
2364}
2365#endif /* !CONFIG_MMU */
2366
adc8cb40
SJ
2367/**
2368 * get_user_pages() - pin user pages in memory
2369 * @start: starting user address
2370 * @nr_pages: number of pages from start to pin
2371 * @gup_flags: flags modifying lookup behaviour
2372 * @pages: array that receives pointers to the pages pinned.
2373 * Should be at least nr_pages long. Or NULL, if caller
2374 * only intends to ensure the pages are faulted in.
adc8cb40 2375 *
64019a2e
PX
2376 * This is the same as get_user_pages_remote(), just with a less-flexible
2377 * calling convention where we assume that the mm being operated on belongs to
2378 * the current task, and doesn't allow passing of a locked parameter. We also
2379 * obviously don't pass FOLL_REMOTE in here.
932f4a63
IW
2380 */
2381long get_user_pages(unsigned long start, unsigned long nr_pages,
54d02069 2382 unsigned int gup_flags, struct page **pages)
932f4a63 2383{
9a863a6a
JG
2384 int locked = 1;
2385
b2cac248 2386 if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_TOUCH))
eddb1c22
JH
2387 return -EINVAL;
2388
afa3c33e 2389 return __get_user_pages_locked(current->mm, start, nr_pages, pages,
b2cac248 2390 &locked, gup_flags);
932f4a63
IW
2391}
2392EXPORT_SYMBOL(get_user_pages);
2bb6d283 2393
acc3c8d1 2394/*
d3649f68 2395 * get_user_pages_unlocked() is suitable to replace the form:
acc3c8d1 2396 *
3e4e28c5 2397 * mmap_read_lock(mm);
64019a2e 2398 * get_user_pages(mm, ..., pages, NULL);
3e4e28c5 2399 * mmap_read_unlock(mm);
d3649f68
CH
2400 *
2401 * with:
2402 *
64019a2e 2403 * get_user_pages_unlocked(mm, ..., pages);
d3649f68
CH
2404 *
2405 * It is functionally equivalent to get_user_pages_fast so
2406 * get_user_pages_fast should be used instead if specific gup_flags
2407 * (e.g. FOLL_FORCE) are not required.
acc3c8d1 2408 */
d3649f68
CH
2409long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
2410 struct page **pages, unsigned int gup_flags)
acc3c8d1 2411{
b2a72dff 2412 int locked = 0;
acc3c8d1 2413
b2cac248 2414 if (!is_valid_gup_args(pages, NULL, &gup_flags,
f04740f5 2415 FOLL_TOUCH | FOLL_UNLOCKABLE))
d64e2dbc
JG
2416 return -EINVAL;
2417
afa3c33e 2418 return __get_user_pages_locked(current->mm, start, nr_pages, pages,
b2cac248 2419 &locked, gup_flags);
4bbd4c77 2420}
d3649f68 2421EXPORT_SYMBOL(get_user_pages_unlocked);
2667f50e
SC
2422
2423/*
67a929e0 2424 * Fast GUP
2667f50e
SC
2425 *
2426 * get_user_pages_fast attempts to pin user pages by walking the page
2427 * tables directly and avoids taking locks. Thus the walker needs to be
2428 * protected from page table pages being freed from under it, and should
2429 * block any THP splits.
2430 *
2431 * One way to achieve this is to have the walker disable interrupts, and
2432 * rely on IPIs from the TLB flushing code blocking before the page table
2433 * pages are freed. This is unsuitable for architectures that do not need
2434 * to broadcast an IPI when invalidating TLBs.
2435 *
2436 * Another way to achieve this is to batch up page table containing pages
2437 * belonging to more than one mm_user, then rcu_sched a callback to free those
2438 * pages. Disabling interrupts will allow the fast_gup walker to both block
2439 * the rcu_sched callback, and an IPI that we broadcast for splitting THPs
2440 * (which is a relatively rare event). The code below adopts this strategy.
2441 *
2442 * Before activating this code, please be aware that the following assumptions
2443 * are currently made:
2444 *
ff2e6d72 2445 * *) Either MMU_GATHER_RCU_TABLE_FREE is enabled, and tlb_remove_table() is used to
e585513b 2446 * free pages containing page tables or TLB flushing requires IPI broadcast.
2667f50e 2447 *
2667f50e
SC
2448 * *) ptes can be read atomically by the architecture.
2449 *
2450 * *) access_ok is sufficient to validate userspace address ranges.
2451 *
2452 * The last two assumptions can be relaxed by the addition of helper functions.
2453 *
2454 * This code is based heavily on the PowerPC implementation by Nick Piggin.
2455 */
67a929e0 2456#ifdef CONFIG_HAVE_FAST_GUP
3faa52c0 2457
a6e79df9
LS
2458/*
2459 * Used in the GUP-fast path to determine whether a pin is permitted for a
2460 * specific folio.
2461 *
2462 * This call assumes the caller has pinned the folio, that the lowest page table
2463 * level still points to this folio, and that interrupts have been disabled.
2464 *
2465 * Writing to pinned file-backed dirty tracked folios is inherently problematic
2466 * (see comment describing the writable_file_mapping_allowed() function). We
2467 * therefore try to avoid the most egregious case of a long-term mapping doing
2468 * so.
2469 *
2470 * This function cannot be as thorough as that one as the VMA is not available
2471 * in the fast path, so instead we whitelist known good cases and if in doubt,
2472 * fall back to the slow path.
2473 */
2474static bool folio_fast_pin_allowed(struct folio *folio, unsigned int flags)
2475{
2476 struct address_space *mapping;
2477 unsigned long mapping_flags;
2478
2479 /*
2480 * If we aren't pinning then no problematic write can occur. A long term
2481 * pin is the most egregious case so this is the one we disallow.
2482 */
2483 if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) !=
2484 (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE))
2485 return true;
2486
2487 /* The folio is pinned, so we can safely access folio fields. */
2488
2489 if (WARN_ON_ONCE(folio_test_slab(folio)))
2490 return false;
2491
2492 /* hugetlb mappings do not require dirty-tracking. */
2493 if (folio_test_hugetlb(folio))
2494 return true;
2495
2496 /*
2497 * GUP-fast disables IRQs. When IRQS are disabled, RCU grace periods
2498 * cannot proceed, which means no actions performed under RCU can
2499 * proceed either.
2500 *
2501 * inodes and thus their mappings are freed under RCU, which means the
2502 * mapping cannot be freed beneath us and thus we can safely dereference
2503 * it.
2504 */
2505 lockdep_assert_irqs_disabled();
2506
2507 /*
2508 * However, there may be operations which _alter_ the mapping, so ensure
2509 * we read it once and only once.
2510 */
2511 mapping = READ_ONCE(folio->mapping);
2512
2513 /*
2514 * The mapping may have been truncated, in any case we cannot determine
2515 * if this mapping is safe - fall back to slow path to determine how to
2516 * proceed.
2517 */
2518 if (!mapping)
2519 return false;
2520
2521 /* Anonymous folios pose no problem. */
2522 mapping_flags = (unsigned long)mapping & PAGE_MAPPING_FLAGS;
2523 if (mapping_flags)
2524 return mapping_flags & PAGE_MAPPING_ANON;
2525
2526 /*
2527 * At this point, we know the mapping is non-null and points to an
2528 * address_space object. The only remaining whitelisted file system is
2529 * shmem.
2530 */
2531 return shmem_mapping(mapping);
2532}
2533
790c7369 2534static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start,
3b78d834 2535 unsigned int flags,
790c7369 2536 struct page **pages)
b59f65fa
KS
2537{
2538 while ((*nr) - nr_start) {
2539 struct page *page = pages[--(*nr)];
2540
2541 ClearPageReferenced(page);
3faa52c0
JH
2542 if (flags & FOLL_PIN)
2543 unpin_user_page(page);
2544 else
2545 put_page(page);
b59f65fa
KS
2546 }
2547}
2548
3010a5ea 2549#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
70cbc3cc
YS
2550/*
2551 * Fast-gup relies on pte change detection to avoid concurrent pgtable
2552 * operations.
2553 *
2554 * To pin the page, fast-gup needs to do below in order:
2555 * (1) pin the page (by prefetching pte), then (2) check pte not changed.
2556 *
2557 * For the rest of pgtable operations where pgtable updates can be racy
2558 * with fast-gup, we need to do (1) clear pte, then (2) check whether page
2559 * is pinned.
2560 *
2561 * Above will work for all pte-level operations, including THP split.
2562 *
2563 * For THP collapse, it's a bit more complicated because fast-gup may be
2564 * walking a pgtable page that is being freed (pte is still valid but pmd
2565 * can be cleared already). To avoid race in such condition, we need to
2566 * also check pmd here to make sure pmd doesn't change (corresponds to
2567 * pmdp_collapse_flush() in the THP collapse code path).
2568 */
2569static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
2570 unsigned long end, unsigned int flags,
2571 struct page **pages, int *nr)
2667f50e 2572{
b59f65fa
KS
2573 struct dev_pagemap *pgmap = NULL;
2574 int nr_start = *nr, ret = 0;
2667f50e 2575 pte_t *ptep, *ptem;
2667f50e
SC
2576
2577 ptem = ptep = pte_offset_map(&pmd, addr);
04dee9e8
HD
2578 if (!ptep)
2579 return 0;
2667f50e 2580 do {
2a4a06da 2581 pte_t pte = ptep_get_lockless(ptep);
b0496fe4
MWO
2582 struct page *page;
2583 struct folio *folio;
2667f50e 2584
d74943a2
DH
2585 /*
2586 * Always fallback to ordinary GUP on PROT_NONE-mapped pages:
2587 * pte_access_permitted() better should reject these pages
2588 * either way: otherwise, GUP-fast might succeed in
2589 * cases where ordinary GUP would fail due to VMA access
2590 * permissions.
2591 */
2592 if (pte_protnone(pte))
e7884f8e
KS
2593 goto pte_unmap;
2594
b798bec4 2595 if (!pte_access_permitted(pte, flags & FOLL_WRITE))
e7884f8e
KS
2596 goto pte_unmap;
2597
b59f65fa 2598 if (pte_devmap(pte)) {
7af75561
IW
2599 if (unlikely(flags & FOLL_LONGTERM))
2600 goto pte_unmap;
2601
b59f65fa
KS
2602 pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
2603 if (unlikely(!pgmap)) {
3b78d834 2604 undo_dev_pagemap(nr, nr_start, flags, pages);
b59f65fa
KS
2605 goto pte_unmap;
2606 }
2607 } else if (pte_special(pte))
2667f50e
SC
2608 goto pte_unmap;
2609
2610 VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
2611 page = pte_page(pte);
2612
b0496fe4
MWO
2613 folio = try_grab_folio(page, 1, flags);
2614 if (!folio)
2667f50e
SC
2615 goto pte_unmap;
2616
8f9ff2de 2617 if (unlikely(folio_is_secretmem(folio))) {
b0496fe4 2618 gup_put_folio(folio, 1, flags);
1507f512
MR
2619 goto pte_unmap;
2620 }
2621
70cbc3cc 2622 if (unlikely(pmd_val(pmd) != pmd_val(*pmdp)) ||
c33c7948 2623 unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
b0496fe4 2624 gup_put_folio(folio, 1, flags);
2667f50e
SC
2625 goto pte_unmap;
2626 }
2627
a6e79df9 2628 if (!folio_fast_pin_allowed(folio, flags)) {
b0496fe4 2629 gup_put_folio(folio, 1, flags);
2667f50e
SC
2630 goto pte_unmap;
2631 }
2632
84209e87 2633 if (!pte_write(pte) && gup_must_unshare(NULL, flags, page)) {
a7f22660
DH
2634 gup_put_folio(folio, 1, flags);
2635 goto pte_unmap;
2636 }
2637
f28d4363
CI
2638 /*
2639 * We need to make the page accessible if and only if we are
2640 * going to access its content (the FOLL_PIN case). Please
2641 * see Documentation/core-api/pin_user_pages.rst for
2642 * details.
2643 */
2644 if (flags & FOLL_PIN) {
2645 ret = arch_make_page_accessible(page);
2646 if (ret) {
b0496fe4 2647 gup_put_folio(folio, 1, flags);
f28d4363
CI
2648 goto pte_unmap;
2649 }
2650 }
b0496fe4 2651 folio_set_referenced(folio);
2667f50e
SC
2652 pages[*nr] = page;
2653 (*nr)++;
2667f50e
SC
2654 } while (ptep++, addr += PAGE_SIZE, addr != end);
2655
2656 ret = 1;
2657
2658pte_unmap:
832d7aa0
CH
2659 if (pgmap)
2660 put_dev_pagemap(pgmap);
2667f50e
SC
2661 pte_unmap(ptem);
2662 return ret;
2663}
2664#else
2665
2666/*
2667 * If we can't determine whether or not a pte is special, then fail immediately
2668 * for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not
2669 * to be special.
2670 *
2671 * For a futex to be placed on a THP tail page, get_futex_key requires a
dadbb612 2672 * get_user_pages_fast_only implementation that can pin pages. Thus it's still
2667f50e
SC
2673 * useful to have gup_huge_pmd even if we can't operate on ptes.
2674 */
70cbc3cc
YS
2675static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
2676 unsigned long end, unsigned int flags,
2677 struct page **pages, int *nr)
2667f50e
SC
2678{
2679 return 0;
2680}
3010a5ea 2681#endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
2667f50e 2682
17596731 2683#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
b59f65fa 2684static int __gup_device_huge(unsigned long pfn, unsigned long addr,
86dfbed4
JH
2685 unsigned long end, unsigned int flags,
2686 struct page **pages, int *nr)
b59f65fa
KS
2687{
2688 int nr_start = *nr;
2689 struct dev_pagemap *pgmap = NULL;
2690
2691 do {
2692 struct page *page = pfn_to_page(pfn);
2693
2694 pgmap = get_dev_pagemap(pfn, pgmap);
2695 if (unlikely(!pgmap)) {
3b78d834 2696 undo_dev_pagemap(nr, nr_start, flags, pages);
6401c4eb 2697 break;
b59f65fa 2698 }
4003f107
LG
2699
2700 if (!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
2701 undo_dev_pagemap(nr, nr_start, flags, pages);
2702 break;
2703 }
2704
b59f65fa
KS
2705 SetPageReferenced(page);
2706 pages[*nr] = page;
0f089235 2707 if (unlikely(try_grab_page(page, flags))) {
3faa52c0 2708 undo_dev_pagemap(nr, nr_start, flags, pages);
6401c4eb 2709 break;
3faa52c0 2710 }
b59f65fa
KS
2711 (*nr)++;
2712 pfn++;
2713 } while (addr += PAGE_SIZE, addr != end);
832d7aa0 2714
6401c4eb 2715 put_dev_pagemap(pgmap);
20b7fee7 2716 return addr == end;
b59f65fa
KS
2717}
2718
a9b6de77 2719static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
86dfbed4
JH
2720 unsigned long end, unsigned int flags,
2721 struct page **pages, int *nr)
b59f65fa
KS
2722{
2723 unsigned long fault_pfn;
a9b6de77
DW
2724 int nr_start = *nr;
2725
2726 fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
86dfbed4 2727 if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr))
a9b6de77 2728 return 0;
b59f65fa 2729
a9b6de77 2730 if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
3b78d834 2731 undo_dev_pagemap(nr, nr_start, flags, pages);
a9b6de77
DW
2732 return 0;
2733 }
2734 return 1;
b59f65fa
KS
2735}
2736
a9b6de77 2737static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
86dfbed4
JH
2738 unsigned long end, unsigned int flags,
2739 struct page **pages, int *nr)
b59f65fa
KS
2740{
2741 unsigned long fault_pfn;
a9b6de77
DW
2742 int nr_start = *nr;
2743
2744 fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
86dfbed4 2745 if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr))
a9b6de77 2746 return 0;
b59f65fa 2747
a9b6de77 2748 if (unlikely(pud_val(orig) != pud_val(*pudp))) {
3b78d834 2749 undo_dev_pagemap(nr, nr_start, flags, pages);
a9b6de77
DW
2750 return 0;
2751 }
2752 return 1;
b59f65fa
KS
2753}
2754#else
a9b6de77 2755static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
86dfbed4
JH
2756 unsigned long end, unsigned int flags,
2757 struct page **pages, int *nr)
b59f65fa
KS
2758{
2759 BUILD_BUG();
2760 return 0;
2761}
2762
a9b6de77 2763static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
86dfbed4
JH
2764 unsigned long end, unsigned int flags,
2765 struct page **pages, int *nr)
b59f65fa
KS
2766{
2767 BUILD_BUG();
2768 return 0;
2769}
2770#endif
2771
a43e9820
JH
2772static int record_subpages(struct page *page, unsigned long addr,
2773 unsigned long end, struct page **pages)
2774{
2775 int nr;
2776
c228afb1
MWO
2777 for (nr = 0; addr != end; nr++, addr += PAGE_SIZE)
2778 pages[nr] = nth_page(page, nr);
a43e9820
JH
2779
2780 return nr;
2781}
2782
cbd34da7
CH
2783#ifdef CONFIG_ARCH_HAS_HUGEPD
2784static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
2785 unsigned long sz)
2786{
2787 unsigned long __boundary = (addr + sz) & ~(sz-1);
2788 return (__boundary - 1 < end - 1) ? __boundary : end;
2789}
2790
2791static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
0cd22afd
JH
2792 unsigned long end, unsigned int flags,
2793 struct page **pages, int *nr)
cbd34da7
CH
2794{
2795 unsigned long pte_end;
09a1626e
MWO
2796 struct page *page;
2797 struct folio *folio;
cbd34da7
CH
2798 pte_t pte;
2799 int refs;
2800
2801 pte_end = (addr + sz) & ~(sz-1);
2802 if (pte_end < end)
2803 end = pte_end;
2804
55ca2263 2805 pte = huge_ptep_get(ptep);
cbd34da7 2806
0cd22afd 2807 if (!pte_access_permitted(pte, flags & FOLL_WRITE))
cbd34da7
CH
2808 return 0;
2809
2810 /* hugepages are never "special" */
2811 VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
2812
09a1626e 2813 page = nth_page(pte_page(pte), (addr & (sz - 1)) >> PAGE_SHIFT);
a43e9820 2814 refs = record_subpages(page, addr, end, pages + *nr);
cbd34da7 2815
09a1626e
MWO
2816 folio = try_grab_folio(page, refs, flags);
2817 if (!folio)
cbd34da7 2818 return 0;
cbd34da7 2819
c33c7948 2820 if (unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
09a1626e 2821 gup_put_folio(folio, refs, flags);
cbd34da7
CH
2822 return 0;
2823 }
2824
a6e79df9 2825 if (!folio_fast_pin_allowed(folio, flags)) {
09a1626e 2826 gup_put_folio(folio, refs, flags);
cbd34da7
CH
2827 return 0;
2828 }
2829
84209e87 2830 if (!pte_write(pte) && gup_must_unshare(NULL, flags, &folio->page)) {
a7f22660
DH
2831 gup_put_folio(folio, refs, flags);
2832 return 0;
2833 }
2834
a43e9820 2835 *nr += refs;
09a1626e 2836 folio_set_referenced(folio);
cbd34da7
CH
2837 return 1;
2838}
2839
2840static int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
0cd22afd 2841 unsigned int pdshift, unsigned long end, unsigned int flags,
cbd34da7
CH
2842 struct page **pages, int *nr)
2843{
2844 pte_t *ptep;
2845 unsigned long sz = 1UL << hugepd_shift(hugepd);
2846 unsigned long next;
2847
2848 ptep = hugepte_offset(hugepd, addr, pdshift);
2849 do {
2850 next = hugepte_addr_end(addr, end, sz);
0cd22afd 2851 if (!gup_hugepte(ptep, sz, addr, end, flags, pages, nr))
cbd34da7
CH
2852 return 0;
2853 } while (ptep++, addr = next, addr != end);
2854
2855 return 1;
2856}
2857#else
2858static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
0cd22afd 2859 unsigned int pdshift, unsigned long end, unsigned int flags,
cbd34da7
CH
2860 struct page **pages, int *nr)
2861{
2862 return 0;
2863}
2864#endif /* CONFIG_ARCH_HAS_HUGEPD */
2865
2667f50e 2866static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
0cd22afd
JH
2867 unsigned long end, unsigned int flags,
2868 struct page **pages, int *nr)
2667f50e 2869{
667ed1f7
MWO
2870 struct page *page;
2871 struct folio *folio;
2667f50e
SC
2872 int refs;
2873
b798bec4 2874 if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
2667f50e
SC
2875 return 0;
2876
7af75561
IW
2877 if (pmd_devmap(orig)) {
2878 if (unlikely(flags & FOLL_LONGTERM))
2879 return 0;
86dfbed4
JH
2880 return __gup_device_huge_pmd(orig, pmdp, addr, end, flags,
2881 pages, nr);
7af75561 2882 }
b59f65fa 2883
c228afb1 2884 page = nth_page(pmd_page(orig), (addr & ~PMD_MASK) >> PAGE_SHIFT);
a43e9820 2885 refs = record_subpages(page, addr, end, pages + *nr);
2667f50e 2886
667ed1f7
MWO
2887 folio = try_grab_folio(page, refs, flags);
2888 if (!folio)
2667f50e 2889 return 0;
2667f50e
SC
2890
2891 if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
667ed1f7 2892 gup_put_folio(folio, refs, flags);
2667f50e
SC
2893 return 0;
2894 }
2895
a6e79df9
LS
2896 if (!folio_fast_pin_allowed(folio, flags)) {
2897 gup_put_folio(folio, refs, flags);
2898 return 0;
2899 }
84209e87 2900 if (!pmd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
a7f22660
DH
2901 gup_put_folio(folio, refs, flags);
2902 return 0;
2903 }
2904
a43e9820 2905 *nr += refs;
667ed1f7 2906 folio_set_referenced(folio);
2667f50e
SC
2907 return 1;
2908}
2909
2910static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
86dfbed4
JH
2911 unsigned long end, unsigned int flags,
2912 struct page **pages, int *nr)
2667f50e 2913{
83afb52e
MWO
2914 struct page *page;
2915 struct folio *folio;
2667f50e
SC
2916 int refs;
2917
b798bec4 2918 if (!pud_access_permitted(orig, flags & FOLL_WRITE))
2667f50e
SC
2919 return 0;
2920
7af75561
IW
2921 if (pud_devmap(orig)) {
2922 if (unlikely(flags & FOLL_LONGTERM))
2923 return 0;
86dfbed4
JH
2924 return __gup_device_huge_pud(orig, pudp, addr, end, flags,
2925 pages, nr);
7af75561 2926 }
b59f65fa 2927
c228afb1 2928 page = nth_page(pud_page(orig), (addr & ~PUD_MASK) >> PAGE_SHIFT);
a43e9820 2929 refs = record_subpages(page, addr, end, pages + *nr);
2667f50e 2930
83afb52e
MWO
2931 folio = try_grab_folio(page, refs, flags);
2932 if (!folio)
2667f50e 2933 return 0;
2667f50e
SC
2934
2935 if (unlikely(pud_val(orig) != pud_val(*pudp))) {
83afb52e 2936 gup_put_folio(folio, refs, flags);
2667f50e
SC
2937 return 0;
2938 }
2939
a6e79df9
LS
2940 if (!folio_fast_pin_allowed(folio, flags)) {
2941 gup_put_folio(folio, refs, flags);
2942 return 0;
2943 }
2944
84209e87 2945 if (!pud_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
a7f22660
DH
2946 gup_put_folio(folio, refs, flags);
2947 return 0;
2948 }
2949
a43e9820 2950 *nr += refs;
83afb52e 2951 folio_set_referenced(folio);
2667f50e
SC
2952 return 1;
2953}
2954
f30c59e9 2955static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
b798bec4 2956 unsigned long end, unsigned int flags,
f30c59e9
AK
2957 struct page **pages, int *nr)
2958{
2959 int refs;
2d7919a2
MWO
2960 struct page *page;
2961 struct folio *folio;
f30c59e9 2962
b798bec4 2963 if (!pgd_access_permitted(orig, flags & FOLL_WRITE))
f30c59e9
AK
2964 return 0;
2965
b59f65fa 2966 BUILD_BUG_ON(pgd_devmap(orig));
a43e9820 2967
c228afb1 2968 page = nth_page(pgd_page(orig), (addr & ~PGDIR_MASK) >> PAGE_SHIFT);
a43e9820 2969 refs = record_subpages(page, addr, end, pages + *nr);
f30c59e9 2970
2d7919a2
MWO
2971 folio = try_grab_folio(page, refs, flags);
2972 if (!folio)
f30c59e9 2973 return 0;
f30c59e9
AK
2974
2975 if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) {
2d7919a2 2976 gup_put_folio(folio, refs, flags);
f30c59e9
AK
2977 return 0;
2978 }
2979
31115034
LS
2980 if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
2981 gup_put_folio(folio, refs, flags);
2982 return 0;
2983 }
2984
a6e79df9
LS
2985 if (!folio_fast_pin_allowed(folio, flags)) {
2986 gup_put_folio(folio, refs, flags);
2987 return 0;
2988 }
2989
a43e9820 2990 *nr += refs;
2d7919a2 2991 folio_set_referenced(folio);
f30c59e9
AK
2992 return 1;
2993}
2994
d3f7b1bb 2995static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned long end,
b798bec4 2996 unsigned int flags, struct page **pages, int *nr)
2667f50e
SC
2997{
2998 unsigned long next;
2999 pmd_t *pmdp;
3000
d3f7b1bb 3001 pmdp = pmd_offset_lockless(pudp, pud, addr);
2667f50e 3002 do {
1180e732 3003 pmd_t pmd = pmdp_get_lockless(pmdp);
2667f50e
SC
3004
3005 next = pmd_addr_end(addr, end);
84c3fc4e 3006 if (!pmd_present(pmd))
2667f50e
SC
3007 return 0;
3008
414fd080
YZ
3009 if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
3010 pmd_devmap(pmd))) {
d74943a2
DH
3011 /* See gup_pte_range() */
3012 if (pmd_protnone(pmd))
2667f50e
SC
3013 return 0;
3014
b798bec4 3015 if (!gup_huge_pmd(pmd, pmdp, addr, next, flags,
2667f50e
SC
3016 pages, nr))
3017 return 0;
3018
f30c59e9
AK
3019 } else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) {
3020 /*
3021 * architecture have different format for hugetlbfs
3022 * pmd format and THP pmd format
3023 */
3024 if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
b798bec4 3025 PMD_SHIFT, next, flags, pages, nr))
f30c59e9 3026 return 0;
70cbc3cc 3027 } else if (!gup_pte_range(pmd, pmdp, addr, next, flags, pages, nr))
2923117b 3028 return 0;
2667f50e
SC
3029 } while (pmdp++, addr = next, addr != end);
3030
3031 return 1;
3032}
3033
d3f7b1bb 3034static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned long end,
b798bec4 3035 unsigned int flags, struct page **pages, int *nr)
2667f50e
SC
3036{
3037 unsigned long next;
3038 pud_t *pudp;
3039
d3f7b1bb 3040 pudp = pud_offset_lockless(p4dp, p4d, addr);
2667f50e 3041 do {
e37c6982 3042 pud_t pud = READ_ONCE(*pudp);
2667f50e
SC
3043
3044 next = pud_addr_end(addr, end);
15494520 3045 if (unlikely(!pud_present(pud)))
2667f50e 3046 return 0;
fcd0ccd8 3047 if (unlikely(pud_huge(pud) || pud_devmap(pud))) {
b798bec4 3048 if (!gup_huge_pud(pud, pudp, addr, next, flags,
f30c59e9
AK
3049 pages, nr))
3050 return 0;
3051 } else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
3052 if (!gup_huge_pd(__hugepd(pud_val(pud)), addr,
b798bec4 3053 PUD_SHIFT, next, flags, pages, nr))
2667f50e 3054 return 0;
d3f7b1bb 3055 } else if (!gup_pmd_range(pudp, pud, addr, next, flags, pages, nr))
2667f50e
SC
3056 return 0;
3057 } while (pudp++, addr = next, addr != end);
3058
3059 return 1;
3060}
3061
d3f7b1bb 3062static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned long end,
b798bec4 3063 unsigned int flags, struct page **pages, int *nr)
c2febafc
KS
3064{
3065 unsigned long next;
3066 p4d_t *p4dp;
3067
d3f7b1bb 3068 p4dp = p4d_offset_lockless(pgdp, pgd, addr);
c2febafc
KS
3069 do {
3070 p4d_t p4d = READ_ONCE(*p4dp);
3071
3072 next = p4d_addr_end(addr, end);
3073 if (p4d_none(p4d))
3074 return 0;
3075 BUILD_BUG_ON(p4d_huge(p4d));
3076 if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) {
3077 if (!gup_huge_pd(__hugepd(p4d_val(p4d)), addr,
b798bec4 3078 P4D_SHIFT, next, flags, pages, nr))
c2febafc 3079 return 0;
d3f7b1bb 3080 } else if (!gup_pud_range(p4dp, p4d, addr, next, flags, pages, nr))
c2febafc
KS
3081 return 0;
3082 } while (p4dp++, addr = next, addr != end);
3083
3084 return 1;
3085}
3086
5b65c467 3087static void gup_pgd_range(unsigned long addr, unsigned long end,
b798bec4 3088 unsigned int flags, struct page **pages, int *nr)
5b65c467
KS
3089{
3090 unsigned long next;
3091 pgd_t *pgdp;
3092
3093 pgdp = pgd_offset(current->mm, addr);
3094 do {
3095 pgd_t pgd = READ_ONCE(*pgdp);
3096
3097 next = pgd_addr_end(addr, end);
3098 if (pgd_none(pgd))
3099 return;
3100 if (unlikely(pgd_huge(pgd))) {
b798bec4 3101 if (!gup_huge_pgd(pgd, pgdp, addr, next, flags,
5b65c467
KS
3102 pages, nr))
3103 return;
3104 } else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) {
3105 if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr,
b798bec4 3106 PGDIR_SHIFT, next, flags, pages, nr))
5b65c467 3107 return;
d3f7b1bb 3108 } else if (!gup_p4d_range(pgdp, pgd, addr, next, flags, pages, nr))
5b65c467
KS
3109 return;
3110 } while (pgdp++, addr = next, addr != end);
3111}
050a9adc
CH
3112#else
3113static inline void gup_pgd_range(unsigned long addr, unsigned long end,
3114 unsigned int flags, struct page **pages, int *nr)
3115{
3116}
3117#endif /* CONFIG_HAVE_FAST_GUP */
5b65c467
KS
3118
3119#ifndef gup_fast_permitted
3120/*
dadbb612 3121 * Check if it's allowed to use get_user_pages_fast_only() for the range, or
5b65c467
KS
3122 * we need to fall back to the slow version:
3123 */
26f4c328 3124static bool gup_fast_permitted(unsigned long start, unsigned long end)
5b65c467 3125{
26f4c328 3126 return true;
5b65c467
KS
3127}
3128#endif
3129
c28b1fc7
JG
3130static unsigned long lockless_pages_from_mm(unsigned long start,
3131 unsigned long end,
3132 unsigned int gup_flags,
3133 struct page **pages)
3134{
3135 unsigned long flags;
3136 int nr_pinned = 0;
57efa1fe 3137 unsigned seq;
c28b1fc7
JG
3138
3139 if (!IS_ENABLED(CONFIG_HAVE_FAST_GUP) ||
3140 !gup_fast_permitted(start, end))
3141 return 0;
3142
57efa1fe
JG
3143 if (gup_flags & FOLL_PIN) {
3144 seq = raw_read_seqcount(&current->mm->write_protect_seq);
3145 if (seq & 1)
3146 return 0;
3147 }
3148
c28b1fc7
JG
3149 /*
3150 * Disable interrupts. The nested form is used, in order to allow full,
3151 * general purpose use of this routine.
3152 *
3153 * With interrupts disabled, we block page table pages from being freed
3154 * from under us. See struct mmu_table_batch comments in
3155 * include/asm-generic/tlb.h for more details.
3156 *
3157 * We do not adopt an rcu_read_lock() here as we also want to block IPIs
3158 * that come from THPs splitting.
3159 */
3160 local_irq_save(flags);
3161 gup_pgd_range(start, end, gup_flags, pages, &nr_pinned);
3162 local_irq_restore(flags);
57efa1fe
JG
3163
3164 /*
3165 * When pinning pages for DMA there could be a concurrent write protect
3166 * from fork() via copy_page_range(), in this case always fail fast GUP.
3167 */
3168 if (gup_flags & FOLL_PIN) {
3169 if (read_seqcount_retry(&current->mm->write_protect_seq, seq)) {
b6a2619c 3170 unpin_user_pages_lockless(pages, nr_pinned);
57efa1fe 3171 return 0;
b6a2619c
DH
3172 } else {
3173 sanity_check_pinned_pages(pages, nr_pinned);
57efa1fe
JG
3174 }
3175 }
c28b1fc7
JG
3176 return nr_pinned;
3177}
3178
3179static int internal_get_user_pages_fast(unsigned long start,
3180 unsigned long nr_pages,
eddb1c22
JH
3181 unsigned int gup_flags,
3182 struct page **pages)
2667f50e 3183{
c28b1fc7
JG
3184 unsigned long len, end;
3185 unsigned long nr_pinned;
b2a72dff 3186 int locked = 0;
c28b1fc7 3187 int ret;
2667f50e 3188
f4000fdf 3189 if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
376a34ef 3190 FOLL_FORCE | FOLL_PIN | FOLL_GET |
4003f107 3191 FOLL_FAST_ONLY | FOLL_NOFAULT |
d74943a2 3192 FOLL_PCI_P2PDMA | FOLL_HONOR_NUMA_FAULT)))
817be129
CH
3193 return -EINVAL;
3194
a458b76a
AA
3195 if (gup_flags & FOLL_PIN)
3196 mm_set_has_pinned_flag(&current->mm->flags);
008cfe44 3197
f81cd178 3198 if (!(gup_flags & FOLL_FAST_ONLY))
da1c55f1 3199 might_lock_read(&current->mm->mmap_lock);
f81cd178 3200
f455c854 3201 start = untagged_addr(start) & PAGE_MASK;
c28b1fc7
JG
3202 len = nr_pages << PAGE_SHIFT;
3203 if (check_add_overflow(start, len, &end))
9883c7f8 3204 return -EOVERFLOW;
6014bc27
LT
3205 if (end > TASK_SIZE_MAX)
3206 return -EFAULT;
96d4f267 3207 if (unlikely(!access_ok((void __user *)start, len)))
c61611f7 3208 return -EFAULT;
73e10a61 3209
c28b1fc7
JG
3210 nr_pinned = lockless_pages_from_mm(start, end, gup_flags, pages);
3211 if (nr_pinned == nr_pages || gup_flags & FOLL_FAST_ONLY)
3212 return nr_pinned;
2667f50e 3213
c28b1fc7
JG
3214 /* Slow path: try to get the remaining pages with get_user_pages */
3215 start += nr_pinned << PAGE_SHIFT;
3216 pages += nr_pinned;
b2a72dff 3217 ret = __gup_longterm_locked(current->mm, start, nr_pages - nr_pinned,
b2cac248 3218 pages, &locked,
f04740f5 3219 gup_flags | FOLL_TOUCH | FOLL_UNLOCKABLE);
c28b1fc7
JG
3220 if (ret < 0) {
3221 /*
3222 * The caller has to unpin the pages we already pinned so
3223 * returning -errno is not an option
3224 */
3225 if (nr_pinned)
3226 return nr_pinned;
3227 return ret;
2667f50e 3228 }
c28b1fc7 3229 return ret + nr_pinned;
2667f50e 3230}
c28b1fc7 3231
dadbb612
SJ
3232/**
3233 * get_user_pages_fast_only() - pin user pages in memory
3234 * @start: starting user address
3235 * @nr_pages: number of pages from start to pin
3236 * @gup_flags: flags modifying pin behaviour
3237 * @pages: array that receives pointers to the pages pinned.
3238 * Should be at least nr_pages long.
3239 *
9e1f0580
JH
3240 * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
3241 * the regular GUP.
9e1f0580
JH
3242 *
3243 * If the architecture does not support this function, simply return with no
3244 * pages pinned.
3245 *
3246 * Careful, careful! COW breaking can go either way, so a non-write
3247 * access can get ambiguous page results. If you call this function without
3248 * 'write' set, you'd better be sure that you're ok with that ambiguity.
3249 */
dadbb612
SJ
3250int get_user_pages_fast_only(unsigned long start, int nr_pages,
3251 unsigned int gup_flags, struct page **pages)
9e1f0580 3252{
9e1f0580
JH
3253 /*
3254 * Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
3255 * because gup fast is always a "pin with a +1 page refcount" request.
376a34ef
JH
3256 *
3257 * FOLL_FAST_ONLY is required in order to match the API description of
3258 * this routine: no fall back to regular ("slow") GUP.
9e1f0580 3259 */
b2cac248 3260 if (!is_valid_gup_args(pages, NULL, &gup_flags,
d64e2dbc
JG
3261 FOLL_GET | FOLL_FAST_ONLY))
3262 return -EINVAL;
9e1f0580 3263
9198a919 3264 return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
9e1f0580 3265}
dadbb612 3266EXPORT_SYMBOL_GPL(get_user_pages_fast_only);
9e1f0580 3267
eddb1c22
JH
3268/**
3269 * get_user_pages_fast() - pin user pages in memory
3faa52c0
JH
3270 * @start: starting user address
3271 * @nr_pages: number of pages from start to pin
3272 * @gup_flags: flags modifying pin behaviour
3273 * @pages: array that receives pointers to the pages pinned.
3274 * Should be at least nr_pages long.
eddb1c22 3275 *
c1e8d7c6 3276 * Attempt to pin user pages in memory without taking mm->mmap_lock.
eddb1c22
JH
3277 * If not successful, it will fall back to taking the lock and
3278 * calling get_user_pages().
3279 *
3280 * Returns number of pages pinned. This may be fewer than the number requested.
3281 * If nr_pages is 0 or negative, returns 0. If no pages were pinned, returns
3282 * -errno.
3283 */
3284int get_user_pages_fast(unsigned long start, int nr_pages,
3285 unsigned int gup_flags, struct page **pages)
3286{
94202f12
JH
3287 /*
3288 * The caller may or may not have explicitly set FOLL_GET; either way is
3289 * OK. However, internally (within mm/gup.c), gup fast variants must set
3290 * FOLL_GET, because gup fast is always a "pin with a +1 page refcount"
3291 * request.
3292 */
b2cac248 3293 if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_GET))
d64e2dbc 3294 return -EINVAL;
eddb1c22
JH
3295 return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
3296}
050a9adc 3297EXPORT_SYMBOL_GPL(get_user_pages_fast);
eddb1c22
JH
3298
3299/**
3300 * pin_user_pages_fast() - pin user pages in memory without taking locks
3301 *
3faa52c0
JH
3302 * @start: starting user address
3303 * @nr_pages: number of pages from start to pin
3304 * @gup_flags: flags modifying pin behaviour
3305 * @pages: array that receives pointers to the pages pinned.
3306 * Should be at least nr_pages long.
3307 *
3308 * Nearly the same as get_user_pages_fast(), except that FOLL_PIN is set. See
3309 * get_user_pages_fast() for documentation on the function arguments, because
3310 * the arguments here are identical.
3311 *
3312 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
72ef5e52 3313 * see Documentation/core-api/pin_user_pages.rst for further details.
c8070b78
DH
3314 *
3315 * Note that if a zero_page is amongst the returned pages, it will not have
3316 * pins in it and unpin_user_page() will not remove pins from it.
eddb1c22
JH
3317 */
3318int pin_user_pages_fast(unsigned long start, int nr_pages,
3319 unsigned int gup_flags, struct page **pages)
3320{
b2cac248 3321 if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_PIN))
3faa52c0 3322 return -EINVAL;
3faa52c0 3323 return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
eddb1c22
JH
3324}
3325EXPORT_SYMBOL_GPL(pin_user_pages_fast);
3326
3327/**
64019a2e 3328 * pin_user_pages_remote() - pin pages of a remote process
eddb1c22 3329 *
3faa52c0
JH
3330 * @mm: mm_struct of target mm
3331 * @start: starting user address
3332 * @nr_pages: number of pages from start to pin
3333 * @gup_flags: flags modifying lookup behaviour
3334 * @pages: array that receives pointers to the pages pinned.
0768c8de 3335 * Should be at least nr_pages long.
3faa52c0
JH
3336 * @locked: pointer to lock flag indicating whether lock is held and
3337 * subsequently whether VM_FAULT_RETRY functionality can be
3338 * utilised. Lock must initially be held.
3339 *
3340 * Nearly the same as get_user_pages_remote(), except that FOLL_PIN is set. See
3341 * get_user_pages_remote() for documentation on the function arguments, because
3342 * the arguments here are identical.
3343 *
3344 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
72ef5e52 3345 * see Documentation/core-api/pin_user_pages.rst for details.
c8070b78
DH
3346 *
3347 * Note that if a zero_page is amongst the returned pages, it will not have
3348 * pins in it and unpin_user_page*() will not remove pins from it.
eddb1c22 3349 */
64019a2e 3350long pin_user_pages_remote(struct mm_struct *mm,
eddb1c22
JH
3351 unsigned long start, unsigned long nr_pages,
3352 unsigned int gup_flags, struct page **pages,
0b295316 3353 int *locked)
eddb1c22 3354{
9a863a6a
JG
3355 int local_locked = 1;
3356
b2cac248 3357 if (!is_valid_gup_args(pages, locked, &gup_flags,
d64e2dbc
JG
3358 FOLL_PIN | FOLL_TOUCH | FOLL_REMOTE))
3359 return 0;
b2cac248 3360 return __gup_longterm_locked(mm, start, nr_pages, pages,
9a863a6a 3361 locked ? locked : &local_locked,
d64e2dbc 3362 gup_flags);
eddb1c22
JH
3363}
3364EXPORT_SYMBOL(pin_user_pages_remote);
3365
3366/**
3367 * pin_user_pages() - pin user pages in memory for use by other devices
3368 *
3faa52c0
JH
3369 * @start: starting user address
3370 * @nr_pages: number of pages from start to pin
3371 * @gup_flags: flags modifying lookup behaviour
3372 * @pages: array that receives pointers to the pages pinned.
0768c8de 3373 * Should be at least nr_pages long.
3faa52c0
JH
3374 *
3375 * Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
3376 * FOLL_PIN is set.
3377 *
3378 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
72ef5e52 3379 * see Documentation/core-api/pin_user_pages.rst for details.
c8070b78
DH
3380 *
3381 * Note that if a zero_page is amongst the returned pages, it will not have
3382 * pins in it and unpin_user_page*() will not remove pins from it.
eddb1c22
JH
3383 */
3384long pin_user_pages(unsigned long start, unsigned long nr_pages,
4c630f30 3385 unsigned int gup_flags, struct page **pages)
eddb1c22 3386{
9a863a6a
JG
3387 int locked = 1;
3388
b2cac248 3389 if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_PIN))
d64e2dbc 3390 return 0;
64019a2e 3391 return __gup_longterm_locked(current->mm, start, nr_pages,
b2cac248 3392 pages, &locked, gup_flags);
eddb1c22
JH
3393}
3394EXPORT_SYMBOL(pin_user_pages);
91429023
JH
3395
3396/*
3397 * pin_user_pages_unlocked() is the FOLL_PIN variant of
3398 * get_user_pages_unlocked(). Behavior is the same, except that this one sets
3399 * FOLL_PIN and rejects FOLL_GET.
c8070b78
DH
3400 *
3401 * Note that if a zero_page is amongst the returned pages, it will not have
3402 * pins in it and unpin_user_page*() will not remove pins from it.
91429023
JH
3403 */
3404long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
3405 struct page **pages, unsigned int gup_flags)
3406{
b2a72dff 3407 int locked = 0;
91429023 3408
b2cac248 3409 if (!is_valid_gup_args(pages, NULL, &gup_flags,
f04740f5 3410 FOLL_PIN | FOLL_TOUCH | FOLL_UNLOCKABLE))
d64e2dbc 3411 return 0;
0768c8de 3412
b2cac248 3413 return __gup_longterm_locked(current->mm, start, nr_pages, pages,
b2a72dff 3414 &locked, gup_flags);
91429023
JH
3415}
3416EXPORT_SYMBOL(pin_user_pages_unlocked);
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