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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
a520110e | 2 | #include <linux/pagewalk.h> |
e6473092 MM |
3 | #include <linux/highmem.h> |
4 | #include <linux/sched.h> | |
d33b9f45 | 5 | #include <linux/hugetlb.h> |
e6473092 MM |
6 | |
7 | static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, | |
2165009b | 8 | struct mm_walk *walk) |
e6473092 MM |
9 | { |
10 | pte_t *pte; | |
11 | int err = 0; | |
7b86ac33 | 12 | const struct mm_walk_ops *ops = walk->ops; |
ace88f10 | 13 | spinlock_t *ptl; |
e6473092 | 14 | |
ace88f10 | 15 | pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); |
556637cd | 16 | for (;;) { |
7b86ac33 | 17 | err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); |
e6473092 MM |
18 | if (err) |
19 | break; | |
556637cd JW |
20 | addr += PAGE_SIZE; |
21 | if (addr == end) | |
22 | break; | |
23 | pte++; | |
24 | } | |
e6473092 | 25 | |
ace88f10 | 26 | pte_unmap_unlock(pte, ptl); |
e6473092 MM |
27 | return err; |
28 | } | |
29 | ||
30 | static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, | |
2165009b | 31 | struct mm_walk *walk) |
e6473092 MM |
32 | { |
33 | pmd_t *pmd; | |
34 | unsigned long next; | |
7b86ac33 | 35 | const struct mm_walk_ops *ops = walk->ops; |
e6473092 MM |
36 | int err = 0; |
37 | ||
38 | pmd = pmd_offset(pud, addr); | |
39 | do { | |
03319327 | 40 | again: |
e6473092 | 41 | next = pmd_addr_end(addr, end); |
48684a65 | 42 | if (pmd_none(*pmd) || !walk->vma) { |
7b86ac33 CH |
43 | if (ops->pte_hole) |
44 | err = ops->pte_hole(addr, next, walk); | |
e6473092 MM |
45 | if (err) |
46 | break; | |
47 | continue; | |
48 | } | |
03319327 DH |
49 | /* |
50 | * This implies that each ->pmd_entry() handler | |
51 | * needs to know about pmd_trans_huge() pmds | |
52 | */ | |
7b86ac33 CH |
53 | if (ops->pmd_entry) |
54 | err = ops->pmd_entry(pmd, addr, next, walk); | |
03319327 DH |
55 | if (err) |
56 | break; | |
57 | ||
58 | /* | |
59 | * Check this here so we only break down trans_huge | |
60 | * pages when we _need_ to | |
61 | */ | |
7b86ac33 | 62 | if (!ops->pte_entry) |
03319327 DH |
63 | continue; |
64 | ||
78ddc534 | 65 | split_huge_pmd(walk->vma, pmd, addr); |
fafaa426 | 66 | if (pmd_trans_unstable(pmd)) |
03319327 DH |
67 | goto again; |
68 | err = walk_pte_range(pmd, addr, next, walk); | |
e6473092 MM |
69 | if (err) |
70 | break; | |
71 | } while (pmd++, addr = next, addr != end); | |
72 | ||
73 | return err; | |
74 | } | |
75 | ||
c2febafc | 76 | static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, |
2165009b | 77 | struct mm_walk *walk) |
e6473092 MM |
78 | { |
79 | pud_t *pud; | |
80 | unsigned long next; | |
7b86ac33 | 81 | const struct mm_walk_ops *ops = walk->ops; |
e6473092 MM |
82 | int err = 0; |
83 | ||
c2febafc | 84 | pud = pud_offset(p4d, addr); |
e6473092 | 85 | do { |
a00cc7d9 | 86 | again: |
e6473092 | 87 | next = pud_addr_end(addr, end); |
a00cc7d9 | 88 | if (pud_none(*pud) || !walk->vma) { |
7b86ac33 CH |
89 | if (ops->pte_hole) |
90 | err = ops->pte_hole(addr, next, walk); | |
e6473092 MM |
91 | if (err) |
92 | break; | |
93 | continue; | |
94 | } | |
a00cc7d9 | 95 | |
7b86ac33 | 96 | if (ops->pud_entry) { |
a00cc7d9 MW |
97 | spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma); |
98 | ||
99 | if (ptl) { | |
7b86ac33 | 100 | err = ops->pud_entry(pud, addr, next, walk); |
a00cc7d9 MW |
101 | spin_unlock(ptl); |
102 | if (err) | |
103 | break; | |
104 | continue; | |
105 | } | |
106 | } | |
107 | ||
108 | split_huge_pud(walk->vma, pud, addr); | |
109 | if (pud_none(*pud)) | |
110 | goto again; | |
111 | ||
7b86ac33 | 112 | if (ops->pmd_entry || ops->pte_entry) |
2165009b | 113 | err = walk_pmd_range(pud, addr, next, walk); |
e6473092 MM |
114 | if (err) |
115 | break; | |
116 | } while (pud++, addr = next, addr != end); | |
117 | ||
118 | return err; | |
119 | } | |
120 | ||
c2febafc KS |
121 | static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, |
122 | struct mm_walk *walk) | |
123 | { | |
124 | p4d_t *p4d; | |
125 | unsigned long next; | |
7b86ac33 | 126 | const struct mm_walk_ops *ops = walk->ops; |
c2febafc KS |
127 | int err = 0; |
128 | ||
129 | p4d = p4d_offset(pgd, addr); | |
130 | do { | |
131 | next = p4d_addr_end(addr, end); | |
132 | if (p4d_none_or_clear_bad(p4d)) { | |
7b86ac33 CH |
133 | if (ops->pte_hole) |
134 | err = ops->pte_hole(addr, next, walk); | |
c2febafc KS |
135 | if (err) |
136 | break; | |
137 | continue; | |
138 | } | |
7b86ac33 | 139 | if (ops->pmd_entry || ops->pte_entry) |
c2febafc KS |
140 | err = walk_pud_range(p4d, addr, next, walk); |
141 | if (err) | |
142 | break; | |
143 | } while (p4d++, addr = next, addr != end); | |
144 | ||
145 | return err; | |
146 | } | |
147 | ||
fafaa426 NH |
148 | static int walk_pgd_range(unsigned long addr, unsigned long end, |
149 | struct mm_walk *walk) | |
150 | { | |
151 | pgd_t *pgd; | |
152 | unsigned long next; | |
7b86ac33 | 153 | const struct mm_walk_ops *ops = walk->ops; |
fafaa426 NH |
154 | int err = 0; |
155 | ||
156 | pgd = pgd_offset(walk->mm, addr); | |
157 | do { | |
158 | next = pgd_addr_end(addr, end); | |
159 | if (pgd_none_or_clear_bad(pgd)) { | |
7b86ac33 CH |
160 | if (ops->pte_hole) |
161 | err = ops->pte_hole(addr, next, walk); | |
fafaa426 NH |
162 | if (err) |
163 | break; | |
164 | continue; | |
165 | } | |
7b86ac33 | 166 | if (ops->pmd_entry || ops->pte_entry) |
c2febafc | 167 | err = walk_p4d_range(pgd, addr, next, walk); |
fafaa426 NH |
168 | if (err) |
169 | break; | |
170 | } while (pgd++, addr = next, addr != end); | |
171 | ||
172 | return err; | |
173 | } | |
174 | ||
116354d1 NH |
175 | #ifdef CONFIG_HUGETLB_PAGE |
176 | static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, | |
177 | unsigned long end) | |
178 | { | |
179 | unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); | |
180 | return boundary < end ? boundary : end; | |
181 | } | |
182 | ||
fafaa426 | 183 | static int walk_hugetlb_range(unsigned long addr, unsigned long end, |
116354d1 NH |
184 | struct mm_walk *walk) |
185 | { | |
fafaa426 | 186 | struct vm_area_struct *vma = walk->vma; |
116354d1 NH |
187 | struct hstate *h = hstate_vma(vma); |
188 | unsigned long next; | |
189 | unsigned long hmask = huge_page_mask(h); | |
7868a208 | 190 | unsigned long sz = huge_page_size(h); |
116354d1 | 191 | pte_t *pte; |
7b86ac33 | 192 | const struct mm_walk_ops *ops = walk->ops; |
116354d1 NH |
193 | int err = 0; |
194 | ||
195 | do { | |
196 | next = hugetlb_entry_end(h, addr, end); | |
7868a208 | 197 | pte = huge_pte_offset(walk->mm, addr & hmask, sz); |
373c4557 JH |
198 | |
199 | if (pte) | |
7b86ac33 CH |
200 | err = ops->hugetlb_entry(pte, hmask, addr, next, walk); |
201 | else if (ops->pte_hole) | |
202 | err = ops->pte_hole(addr, next, walk); | |
373c4557 | 203 | |
116354d1 | 204 | if (err) |
fafaa426 | 205 | break; |
116354d1 NH |
206 | } while (addr = next, addr != end); |
207 | ||
fafaa426 | 208 | return err; |
116354d1 | 209 | } |
6c6d5280 | 210 | |
6c6d5280 | 211 | #else /* CONFIG_HUGETLB_PAGE */ |
fafaa426 | 212 | static int walk_hugetlb_range(unsigned long addr, unsigned long end, |
6c6d5280 KM |
213 | struct mm_walk *walk) |
214 | { | |
215 | return 0; | |
216 | } | |
217 | ||
218 | #endif /* CONFIG_HUGETLB_PAGE */ | |
219 | ||
fafaa426 NH |
220 | /* |
221 | * Decide whether we really walk over the current vma on [@start, @end) | |
222 | * or skip it via the returned value. Return 0 if we do walk over the | |
223 | * current vma, and return 1 if we skip the vma. Negative values means | |
224 | * error, where we abort the current walk. | |
fafaa426 NH |
225 | */ |
226 | static int walk_page_test(unsigned long start, unsigned long end, | |
227 | struct mm_walk *walk) | |
228 | { | |
229 | struct vm_area_struct *vma = walk->vma; | |
7b86ac33 | 230 | const struct mm_walk_ops *ops = walk->ops; |
6c6d5280 | 231 | |
7b86ac33 CH |
232 | if (ops->test_walk) |
233 | return ops->test_walk(start, end, walk); | |
fafaa426 NH |
234 | |
235 | /* | |
48684a65 NH |
236 | * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP |
237 | * range, so we don't walk over it as we do for normal vmas. However, | |
238 | * Some callers are interested in handling hole range and they don't | |
239 | * want to just ignore any single address range. Such users certainly | |
240 | * define their ->pte_hole() callbacks, so let's delegate them to handle | |
241 | * vma(VM_PFNMAP). | |
fafaa426 | 242 | */ |
48684a65 NH |
243 | if (vma->vm_flags & VM_PFNMAP) { |
244 | int err = 1; | |
7b86ac33 CH |
245 | if (ops->pte_hole) |
246 | err = ops->pte_hole(start, end, walk); | |
48684a65 NH |
247 | return err ? err : 1; |
248 | } | |
fafaa426 NH |
249 | return 0; |
250 | } | |
251 | ||
252 | static int __walk_page_range(unsigned long start, unsigned long end, | |
253 | struct mm_walk *walk) | |
254 | { | |
255 | int err = 0; | |
256 | struct vm_area_struct *vma = walk->vma; | |
ecaad8ac TH |
257 | const struct mm_walk_ops *ops = walk->ops; |
258 | ||
259 | if (vma && ops->pre_vma) { | |
260 | err = ops->pre_vma(start, end, walk); | |
261 | if (err) | |
262 | return err; | |
263 | } | |
fafaa426 NH |
264 | |
265 | if (vma && is_vm_hugetlb_page(vma)) { | |
ecaad8ac | 266 | if (ops->hugetlb_entry) |
fafaa426 NH |
267 | err = walk_hugetlb_range(start, end, walk); |
268 | } else | |
269 | err = walk_pgd_range(start, end, walk); | |
270 | ||
ecaad8ac TH |
271 | if (vma && ops->post_vma) |
272 | ops->post_vma(walk); | |
273 | ||
fafaa426 NH |
274 | return err; |
275 | } | |
116354d1 | 276 | |
e6473092 | 277 | /** |
fafaa426 | 278 | * walk_page_range - walk page table with caller specific callbacks |
7b86ac33 CH |
279 | * @mm: mm_struct representing the target process of page table walk |
280 | * @start: start address of the virtual address range | |
281 | * @end: end address of the virtual address range | |
282 | * @ops: operation to call during the walk | |
283 | * @private: private data for callbacks' usage | |
e6473092 | 284 | * |
7b86ac33 | 285 | * Recursively walk the page table tree of the process represented by @mm |
fafaa426 NH |
286 | * within the virtual address range [@start, @end). During walking, we can do |
287 | * some caller-specific works for each entry, by setting up pmd_entry(), | |
288 | * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these | |
289 | * callbacks, the associated entries/pages are just ignored. | |
290 | * The return values of these callbacks are commonly defined like below: | |
a5d09bed | 291 | * |
fafaa426 NH |
292 | * - 0 : succeeded to handle the current entry, and if you don't reach the |
293 | * end address yet, continue to walk. | |
294 | * - >0 : succeeded to handle the current entry, and return to the caller | |
295 | * with caller specific value. | |
296 | * - <0 : failed to handle the current entry, and return to the caller | |
297 | * with error code. | |
e6473092 | 298 | * |
fafaa426 NH |
299 | * Before starting to walk page table, some callers want to check whether |
300 | * they really want to walk over the current vma, typically by checking | |
7b86ac33 | 301 | * its vm_flags. walk_page_test() and @ops->test_walk() are used for this |
fafaa426 | 302 | * purpose. |
e6473092 | 303 | * |
ecaad8ac TH |
304 | * If operations need to be staged before and committed after a vma is walked, |
305 | * there are two callbacks, pre_vma() and post_vma(). Note that post_vma(), | |
306 | * since it is intended to handle commit-type operations, can't return any | |
307 | * errors. | |
308 | * | |
fafaa426 NH |
309 | * struct mm_walk keeps current values of some common data like vma and pmd, |
310 | * which are useful for the access from callbacks. If you want to pass some | |
7b86ac33 | 311 | * caller-specific data to callbacks, @private should be helpful. |
c27fe4c8 | 312 | * |
fafaa426 | 313 | * Locking: |
7b86ac33 CH |
314 | * Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_sem, |
315 | * because these function traverse vma list and/or access to vma's data. | |
e6473092 | 316 | */ |
7b86ac33 CH |
317 | int walk_page_range(struct mm_struct *mm, unsigned long start, |
318 | unsigned long end, const struct mm_walk_ops *ops, | |
319 | void *private) | |
e6473092 | 320 | { |
e6473092 | 321 | int err = 0; |
fafaa426 NH |
322 | unsigned long next; |
323 | struct vm_area_struct *vma; | |
7b86ac33 CH |
324 | struct mm_walk walk = { |
325 | .ops = ops, | |
326 | .mm = mm, | |
327 | .private = private, | |
328 | }; | |
e6473092 | 329 | |
fafaa426 NH |
330 | if (start >= end) |
331 | return -EINVAL; | |
e6473092 | 332 | |
7b86ac33 | 333 | if (!walk.mm) |
2165009b DH |
334 | return -EINVAL; |
335 | ||
b4bc7817 | 336 | lockdep_assert_held(&walk.mm->mmap_sem); |
a9ff785e | 337 | |
7b86ac33 | 338 | vma = find_vma(walk.mm, start); |
e6473092 | 339 | do { |
fafaa426 | 340 | if (!vma) { /* after the last vma */ |
7b86ac33 | 341 | walk.vma = NULL; |
fafaa426 NH |
342 | next = end; |
343 | } else if (start < vma->vm_start) { /* outside vma */ | |
7b86ac33 | 344 | walk.vma = NULL; |
fafaa426 NH |
345 | next = min(end, vma->vm_start); |
346 | } else { /* inside vma */ | |
7b86ac33 | 347 | walk.vma = vma; |
fafaa426 NH |
348 | next = min(end, vma->vm_end); |
349 | vma = vma->vm_next; | |
5f0af70a | 350 | |
7b86ac33 | 351 | err = walk_page_test(start, next, &walk); |
f6837395 NH |
352 | if (err > 0) { |
353 | /* | |
354 | * positive return values are purely for | |
355 | * controlling the pagewalk, so should never | |
356 | * be passed to the callers. | |
357 | */ | |
358 | err = 0; | |
a9ff785e | 359 | continue; |
f6837395 | 360 | } |
fafaa426 | 361 | if (err < 0) |
e6473092 | 362 | break; |
e6473092 | 363 | } |
7b86ac33 CH |
364 | if (walk.vma || walk.ops->pte_hole) |
365 | err = __walk_page_range(start, next, &walk); | |
e6473092 MM |
366 | if (err) |
367 | break; | |
fafaa426 | 368 | } while (start = next, start < end); |
e6473092 MM |
369 | return err; |
370 | } | |
900fc5f1 | 371 | |
7b86ac33 CH |
372 | int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, |
373 | void *private) | |
900fc5f1 | 374 | { |
7b86ac33 CH |
375 | struct mm_walk walk = { |
376 | .ops = ops, | |
377 | .mm = vma->vm_mm, | |
378 | .vma = vma, | |
379 | .private = private, | |
380 | }; | |
900fc5f1 NH |
381 | int err; |
382 | ||
7b86ac33 | 383 | if (!walk.mm) |
900fc5f1 NH |
384 | return -EINVAL; |
385 | ||
b4bc7817 | 386 | lockdep_assert_held(&walk.mm->mmap_sem); |
7b86ac33 CH |
387 | |
388 | err = walk_page_test(vma->vm_start, vma->vm_end, &walk); | |
900fc5f1 NH |
389 | if (err > 0) |
390 | return 0; | |
391 | if (err < 0) | |
392 | return err; | |
7b86ac33 | 393 | return __walk_page_range(vma->vm_start, vma->vm_end, &walk); |
900fc5f1 | 394 | } |
ecaad8ac TH |
395 | |
396 | /** | |
397 | * walk_page_mapping - walk all memory areas mapped into a struct address_space. | |
398 | * @mapping: Pointer to the struct address_space | |
399 | * @first_index: First page offset in the address_space | |
400 | * @nr: Number of incremental page offsets to cover | |
401 | * @ops: operation to call during the walk | |
402 | * @private: private data for callbacks' usage | |
403 | * | |
404 | * This function walks all memory areas mapped into a struct address_space. | |
405 | * The walk is limited to only the given page-size index range, but if | |
406 | * the index boundaries cross a huge page-table entry, that entry will be | |
407 | * included. | |
408 | * | |
409 | * Also see walk_page_range() for additional information. | |
410 | * | |
411 | * Locking: | |
412 | * This function can't require that the struct mm_struct::mmap_sem is held, | |
413 | * since @mapping may be mapped by multiple processes. Instead | |
414 | * @mapping->i_mmap_rwsem must be held. This might have implications in the | |
415 | * callbacks, and it's up tho the caller to ensure that the | |
416 | * struct mm_struct::mmap_sem is not needed. | |
417 | * | |
418 | * Also this means that a caller can't rely on the struct | |
419 | * vm_area_struct::vm_flags to be constant across a call, | |
420 | * except for immutable flags. Callers requiring this shouldn't use | |
421 | * this function. | |
422 | * | |
423 | * Return: 0 on success, negative error code on failure, positive number on | |
424 | * caller defined premature termination. | |
425 | */ | |
426 | int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, | |
427 | pgoff_t nr, const struct mm_walk_ops *ops, | |
428 | void *private) | |
429 | { | |
430 | struct mm_walk walk = { | |
431 | .ops = ops, | |
432 | .private = private, | |
433 | }; | |
434 | struct vm_area_struct *vma; | |
435 | pgoff_t vba, vea, cba, cea; | |
436 | unsigned long start_addr, end_addr; | |
437 | int err = 0; | |
438 | ||
439 | lockdep_assert_held(&mapping->i_mmap_rwsem); | |
440 | vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index, | |
441 | first_index + nr - 1) { | |
442 | /* Clip to the vma */ | |
443 | vba = vma->vm_pgoff; | |
444 | vea = vba + vma_pages(vma); | |
445 | cba = first_index; | |
446 | cba = max(cba, vba); | |
447 | cea = first_index + nr; | |
448 | cea = min(cea, vea); | |
449 | ||
450 | start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start; | |
451 | end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start; | |
452 | if (start_addr >= end_addr) | |
453 | continue; | |
454 | ||
455 | walk.vma = vma; | |
456 | walk.mm = vma->vm_mm; | |
457 | ||
458 | err = walk_page_test(vma->vm_start, vma->vm_end, &walk); | |
459 | if (err > 0) { | |
460 | err = 0; | |
461 | break; | |
462 | } else if (err < 0) | |
463 | break; | |
464 | ||
465 | err = __walk_page_range(start_addr, end_addr, &walk); | |
466 | if (err) | |
467 | break; | |
468 | } | |
469 | ||
470 | return err; | |
471 | } |