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1#include <linux/mm.h>
2#include <linux/highmem.h>
3#include <linux/sched.h>
4#include <linux/hugetlb.h>
5
6static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
7 struct mm_walk *walk)
8{
9 pte_t *pte;
10 int err = 0;
11
12 pte = pte_offset_map(pmd, addr);
13 for (;;) {
14 err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
15 if (err)
16 break;
17 addr += PAGE_SIZE;
18 if (addr == end)
19 break;
20 pte++;
21 }
22
23 pte_unmap(pte);
24 return err;
25}
26
27static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
28 struct mm_walk *walk)
29{
30 pmd_t *pmd;
31 unsigned long next;
32 int err = 0;
33
34 pmd = pmd_offset(pud, addr);
35 do {
36again:
37 next = pmd_addr_end(addr, end);
38 if (pmd_none(*pmd)) {
39 if (walk->pte_hole)
40 err = walk->pte_hole(addr, next, walk);
41 if (err)
42 break;
43 continue;
44 }
45 /*
46 * This implies that each ->pmd_entry() handler
47 * needs to know about pmd_trans_huge() pmds
48 */
49 if (walk->pmd_entry)
50 err = walk->pmd_entry(pmd, addr, next, walk);
51 if (err)
52 break;
53
54 /*
55 * Check this here so we only break down trans_huge
56 * pages when we _need_ to
57 */
58 if (!walk->pte_entry)
59 continue;
60
61 split_huge_page_pmd(walk->mm, pmd);
62 if (pmd_none_or_clear_bad(pmd))
63 goto again;
64 err = walk_pte_range(pmd, addr, next, walk);
65 if (err)
66 break;
67 } while (pmd++, addr = next, addr != end);
68
69 return err;
70}
71
72static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
73 struct mm_walk *walk)
74{
75 pud_t *pud;
76 unsigned long next;
77 int err = 0;
78
79 pud = pud_offset(pgd, addr);
80 do {
81 next = pud_addr_end(addr, end);
82 if (pud_none_or_clear_bad(pud)) {
83 if (walk->pte_hole)
84 err = walk->pte_hole(addr, next, walk);
85 if (err)
86 break;
87 continue;
88 }
89 if (walk->pud_entry)
90 err = walk->pud_entry(pud, addr, next, walk);
91 if (!err && (walk->pmd_entry || walk->pte_entry))
92 err = walk_pmd_range(pud, addr, next, walk);
93 if (err)
94 break;
95 } while (pud++, addr = next, addr != end);
96
97 return err;
98}
99
100#ifdef CONFIG_HUGETLB_PAGE
101static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
102 unsigned long end)
103{
104 unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
105 return boundary < end ? boundary : end;
106}
107
108static int walk_hugetlb_range(struct vm_area_struct *vma,
109 unsigned long addr, unsigned long end,
110 struct mm_walk *walk)
111{
112 struct hstate *h = hstate_vma(vma);
113 unsigned long next;
114 unsigned long hmask = huge_page_mask(h);
115 pte_t *pte;
116 int err = 0;
117
118 do {
119 next = hugetlb_entry_end(h, addr, end);
120 pte = huge_pte_offset(walk->mm, addr & hmask);
121 if (pte && walk->hugetlb_entry)
122 err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
123 if (err)
124 return err;
125 } while (addr = next, addr != end);
126
127 return 0;
128}
129
130static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
131{
132 struct vm_area_struct *vma;
133
134 /* We don't need vma lookup at all. */
135 if (!walk->hugetlb_entry)
136 return NULL;
137
138 VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
139 vma = find_vma(walk->mm, addr);
140 if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma))
141 return vma;
142
143 return NULL;
144}
145
146#else /* CONFIG_HUGETLB_PAGE */
147static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
148{
149 return NULL;
150}
151
152static int walk_hugetlb_range(struct vm_area_struct *vma,
153 unsigned long addr, unsigned long end,
154 struct mm_walk *walk)
155{
156 return 0;
157}
158
159#endif /* CONFIG_HUGETLB_PAGE */
160
161
162
163/**
164 * walk_page_range - walk a memory map's page tables with a callback
165 * @mm: memory map to walk
166 * @addr: starting address
167 * @end: ending address
168 * @walk: set of callbacks to invoke for each level of the tree
169 *
170 * Recursively walk the page table for the memory area in a VMA,
171 * calling supplied callbacks. Callbacks are called in-order (first
172 * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
173 * etc.). If lower-level callbacks are omitted, walking depth is reduced.
174 *
175 * Each callback receives an entry pointer and the start and end of the
176 * associated range, and a copy of the original mm_walk for access to
177 * the ->private or ->mm fields.
178 *
179 * Usually no locks are taken, but splitting transparent huge page may
180 * take page table lock. And the bottom level iterator will map PTE
181 * directories from highmem if necessary.
182 *
183 * If any callback returns a non-zero value, the walk is aborted and
184 * the return value is propagated back to the caller. Otherwise 0 is returned.
185 *
186 * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
187 * is !NULL.
188 */
189int walk_page_range(unsigned long addr, unsigned long end,
190 struct mm_walk *walk)
191{
192 pgd_t *pgd;
193 unsigned long next;
194 int err = 0;
195
196 if (addr >= end)
197 return err;
198
199 if (!walk->mm)
200 return -EINVAL;
201
202 pgd = pgd_offset(walk->mm, addr);
203 do {
204 struct vm_area_struct *vma;
205
206 next = pgd_addr_end(addr, end);
207
208 /*
209 * handle hugetlb vma individually because pagetable walk for
210 * the hugetlb page is dependent on the architecture and
211 * we can't handled it in the same manner as non-huge pages.
212 */
213 vma = hugetlb_vma(addr, walk);
214 if (vma) {
215 if (vma->vm_end < next)
216 next = vma->vm_end;
217 /*
218 * Hugepage is very tightly coupled with vma, so
219 * walk through hugetlb entries within a given vma.
220 */
221 err = walk_hugetlb_range(vma, addr, next, walk);
222 if (err)
223 break;
224 pgd = pgd_offset(walk->mm, next);
225 continue;
226 }
227
228 if (pgd_none_or_clear_bad(pgd)) {
229 if (walk->pte_hole)
230 err = walk->pte_hole(addr, next, walk);
231 if (err)
232 break;
233 pgd++;
234 continue;
235 }
236 if (walk->pgd_entry)
237 err = walk->pgd_entry(pgd, addr, next, walk);
238 if (!err &&
239 (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
240 err = walk_pud_range(pgd, addr, next, walk);
241 if (err)
242 break;
243 pgd++;
244 } while (addr = next, addr != end);
245
246 return err;
247}
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/pagewalk.h>
3#include <linux/highmem.h>
4#include <linux/sched.h>
5#include <linux/hugetlb.h>
6
7/*
8 * We want to know the real level where a entry is located ignoring any
9 * folding of levels which may be happening. For example if p4d is folded then
10 * a missing entry found at level 1 (p4d) is actually at level 0 (pgd).
11 */
12static int real_depth(int depth)
13{
14 if (depth == 3 && PTRS_PER_PMD == 1)
15 depth = 2;
16 if (depth == 2 && PTRS_PER_PUD == 1)
17 depth = 1;
18 if (depth == 1 && PTRS_PER_P4D == 1)
19 depth = 0;
20 return depth;
21}
22
23static int walk_pte_range_inner(pte_t *pte, unsigned long addr,
24 unsigned long end, struct mm_walk *walk)
25{
26 const struct mm_walk_ops *ops = walk->ops;
27 int err = 0;
28
29 for (;;) {
30 err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
31 if (err)
32 break;
33 if (addr >= end - PAGE_SIZE)
34 break;
35 addr += PAGE_SIZE;
36 pte++;
37 }
38 return err;
39}
40
41static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
42 struct mm_walk *walk)
43{
44 pte_t *pte;
45 int err = 0;
46 spinlock_t *ptl;
47
48 if (walk->no_vma) {
49 /*
50 * pte_offset_map() might apply user-specific validation.
51 * Indeed, on x86_64 the pmd entries set up by init_espfix_ap()
52 * fit its pmd_bad() check (_PAGE_NX set and _PAGE_RW clear),
53 * and CONFIG_EFI_PGT_DUMP efi_mm goes so far as to walk them.
54 */
55 if (walk->mm == &init_mm || addr >= TASK_SIZE)
56 pte = pte_offset_kernel(pmd, addr);
57 else
58 pte = pte_offset_map(pmd, addr);
59 if (pte) {
60 err = walk_pte_range_inner(pte, addr, end, walk);
61 if (walk->mm != &init_mm && addr < TASK_SIZE)
62 pte_unmap(pte);
63 }
64 } else {
65 pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
66 if (pte) {
67 err = walk_pte_range_inner(pte, addr, end, walk);
68 pte_unmap_unlock(pte, ptl);
69 }
70 }
71 if (!pte)
72 walk->action = ACTION_AGAIN;
73 return err;
74}
75
76#ifdef CONFIG_ARCH_HAS_HUGEPD
77static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr,
78 unsigned long end, struct mm_walk *walk, int pdshift)
79{
80 int err = 0;
81 const struct mm_walk_ops *ops = walk->ops;
82 int shift = hugepd_shift(*phpd);
83 int page_size = 1 << shift;
84
85 if (!ops->pte_entry)
86 return 0;
87
88 if (addr & (page_size - 1))
89 return 0;
90
91 for (;;) {
92 pte_t *pte;
93
94 spin_lock(&walk->mm->page_table_lock);
95 pte = hugepte_offset(*phpd, addr, pdshift);
96 err = ops->pte_entry(pte, addr, addr + page_size, walk);
97 spin_unlock(&walk->mm->page_table_lock);
98
99 if (err)
100 break;
101 if (addr >= end - page_size)
102 break;
103 addr += page_size;
104 }
105 return err;
106}
107#else
108static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr,
109 unsigned long end, struct mm_walk *walk, int pdshift)
110{
111 return 0;
112}
113#endif
114
115static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
116 struct mm_walk *walk)
117{
118 pmd_t *pmd;
119 unsigned long next;
120 const struct mm_walk_ops *ops = walk->ops;
121 int err = 0;
122 int depth = real_depth(3);
123
124 pmd = pmd_offset(pud, addr);
125 do {
126again:
127 next = pmd_addr_end(addr, end);
128 if (pmd_none(*pmd)) {
129 if (ops->pte_hole)
130 err = ops->pte_hole(addr, next, depth, walk);
131 if (err)
132 break;
133 continue;
134 }
135
136 walk->action = ACTION_SUBTREE;
137
138 /*
139 * This implies that each ->pmd_entry() handler
140 * needs to know about pmd_trans_huge() pmds
141 */
142 if (ops->pmd_entry)
143 err = ops->pmd_entry(pmd, addr, next, walk);
144 if (err)
145 break;
146
147 if (walk->action == ACTION_AGAIN)
148 goto again;
149
150 /*
151 * Check this here so we only break down trans_huge
152 * pages when we _need_ to
153 */
154 if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) ||
155 walk->action == ACTION_CONTINUE ||
156 !(ops->pte_entry))
157 continue;
158
159 if (walk->vma)
160 split_huge_pmd(walk->vma, pmd, addr);
161
162 if (is_hugepd(__hugepd(pmd_val(*pmd))))
163 err = walk_hugepd_range((hugepd_t *)pmd, addr, next, walk, PMD_SHIFT);
164 else
165 err = walk_pte_range(pmd, addr, next, walk);
166 if (err)
167 break;
168
169 if (walk->action == ACTION_AGAIN)
170 goto again;
171
172 } while (pmd++, addr = next, addr != end);
173
174 return err;
175}
176
177static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
178 struct mm_walk *walk)
179{
180 pud_t *pud;
181 unsigned long next;
182 const struct mm_walk_ops *ops = walk->ops;
183 int err = 0;
184 int depth = real_depth(2);
185
186 pud = pud_offset(p4d, addr);
187 do {
188 again:
189 next = pud_addr_end(addr, end);
190 if (pud_none(*pud)) {
191 if (ops->pte_hole)
192 err = ops->pte_hole(addr, next, depth, walk);
193 if (err)
194 break;
195 continue;
196 }
197
198 walk->action = ACTION_SUBTREE;
199
200 if (ops->pud_entry)
201 err = ops->pud_entry(pud, addr, next, walk);
202 if (err)
203 break;
204
205 if (walk->action == ACTION_AGAIN)
206 goto again;
207
208 if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) ||
209 walk->action == ACTION_CONTINUE ||
210 !(ops->pmd_entry || ops->pte_entry))
211 continue;
212
213 if (walk->vma)
214 split_huge_pud(walk->vma, pud, addr);
215 if (pud_none(*pud))
216 goto again;
217
218 if (is_hugepd(__hugepd(pud_val(*pud))))
219 err = walk_hugepd_range((hugepd_t *)pud, addr, next, walk, PUD_SHIFT);
220 else
221 err = walk_pmd_range(pud, addr, next, walk);
222 if (err)
223 break;
224 } while (pud++, addr = next, addr != end);
225
226 return err;
227}
228
229static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
230 struct mm_walk *walk)
231{
232 p4d_t *p4d;
233 unsigned long next;
234 const struct mm_walk_ops *ops = walk->ops;
235 int err = 0;
236 int depth = real_depth(1);
237
238 p4d = p4d_offset(pgd, addr);
239 do {
240 next = p4d_addr_end(addr, end);
241 if (p4d_none_or_clear_bad(p4d)) {
242 if (ops->pte_hole)
243 err = ops->pte_hole(addr, next, depth, walk);
244 if (err)
245 break;
246 continue;
247 }
248 if (ops->p4d_entry) {
249 err = ops->p4d_entry(p4d, addr, next, walk);
250 if (err)
251 break;
252 }
253 if (is_hugepd(__hugepd(p4d_val(*p4d))))
254 err = walk_hugepd_range((hugepd_t *)p4d, addr, next, walk, P4D_SHIFT);
255 else if (ops->pud_entry || ops->pmd_entry || ops->pte_entry)
256 err = walk_pud_range(p4d, addr, next, walk);
257 if (err)
258 break;
259 } while (p4d++, addr = next, addr != end);
260
261 return err;
262}
263
264static int walk_pgd_range(unsigned long addr, unsigned long end,
265 struct mm_walk *walk)
266{
267 pgd_t *pgd;
268 unsigned long next;
269 const struct mm_walk_ops *ops = walk->ops;
270 int err = 0;
271
272 if (walk->pgd)
273 pgd = walk->pgd + pgd_index(addr);
274 else
275 pgd = pgd_offset(walk->mm, addr);
276 do {
277 next = pgd_addr_end(addr, end);
278 if (pgd_none_or_clear_bad(pgd)) {
279 if (ops->pte_hole)
280 err = ops->pte_hole(addr, next, 0, walk);
281 if (err)
282 break;
283 continue;
284 }
285 if (ops->pgd_entry) {
286 err = ops->pgd_entry(pgd, addr, next, walk);
287 if (err)
288 break;
289 }
290 if (is_hugepd(__hugepd(pgd_val(*pgd))))
291 err = walk_hugepd_range((hugepd_t *)pgd, addr, next, walk, PGDIR_SHIFT);
292 else if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry || ops->pte_entry)
293 err = walk_p4d_range(pgd, addr, next, walk);
294 if (err)
295 break;
296 } while (pgd++, addr = next, addr != end);
297
298 return err;
299}
300
301#ifdef CONFIG_HUGETLB_PAGE
302static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
303 unsigned long end)
304{
305 unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
306 return boundary < end ? boundary : end;
307}
308
309static int walk_hugetlb_range(unsigned long addr, unsigned long end,
310 struct mm_walk *walk)
311{
312 struct vm_area_struct *vma = walk->vma;
313 struct hstate *h = hstate_vma(vma);
314 unsigned long next;
315 unsigned long hmask = huge_page_mask(h);
316 unsigned long sz = huge_page_size(h);
317 pte_t *pte;
318 const struct mm_walk_ops *ops = walk->ops;
319 int err = 0;
320
321 hugetlb_vma_lock_read(vma);
322 do {
323 next = hugetlb_entry_end(h, addr, end);
324 pte = hugetlb_walk(vma, addr & hmask, sz);
325 if (pte)
326 err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
327 else if (ops->pte_hole)
328 err = ops->pte_hole(addr, next, -1, walk);
329 if (err)
330 break;
331 } while (addr = next, addr != end);
332 hugetlb_vma_unlock_read(vma);
333
334 return err;
335}
336
337#else /* CONFIG_HUGETLB_PAGE */
338static int walk_hugetlb_range(unsigned long addr, unsigned long end,
339 struct mm_walk *walk)
340{
341 return 0;
342}
343
344#endif /* CONFIG_HUGETLB_PAGE */
345
346/*
347 * Decide whether we really walk over the current vma on [@start, @end)
348 * or skip it via the returned value. Return 0 if we do walk over the
349 * current vma, and return 1 if we skip the vma. Negative values means
350 * error, where we abort the current walk.
351 */
352static int walk_page_test(unsigned long start, unsigned long end,
353 struct mm_walk *walk)
354{
355 struct vm_area_struct *vma = walk->vma;
356 const struct mm_walk_ops *ops = walk->ops;
357
358 if (ops->test_walk)
359 return ops->test_walk(start, end, walk);
360
361 /*
362 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
363 * range, so we don't walk over it as we do for normal vmas. However,
364 * Some callers are interested in handling hole range and they don't
365 * want to just ignore any single address range. Such users certainly
366 * define their ->pte_hole() callbacks, so let's delegate them to handle
367 * vma(VM_PFNMAP).
368 */
369 if (vma->vm_flags & VM_PFNMAP) {
370 int err = 1;
371 if (ops->pte_hole)
372 err = ops->pte_hole(start, end, -1, walk);
373 return err ? err : 1;
374 }
375 return 0;
376}
377
378static int __walk_page_range(unsigned long start, unsigned long end,
379 struct mm_walk *walk)
380{
381 int err = 0;
382 struct vm_area_struct *vma = walk->vma;
383 const struct mm_walk_ops *ops = walk->ops;
384
385 if (ops->pre_vma) {
386 err = ops->pre_vma(start, end, walk);
387 if (err)
388 return err;
389 }
390
391 if (is_vm_hugetlb_page(vma)) {
392 if (ops->hugetlb_entry)
393 err = walk_hugetlb_range(start, end, walk);
394 } else
395 err = walk_pgd_range(start, end, walk);
396
397 if (ops->post_vma)
398 ops->post_vma(walk);
399
400 return err;
401}
402
403static inline void process_mm_walk_lock(struct mm_struct *mm,
404 enum page_walk_lock walk_lock)
405{
406 if (walk_lock == PGWALK_RDLOCK)
407 mmap_assert_locked(mm);
408 else
409 mmap_assert_write_locked(mm);
410}
411
412static inline void process_vma_walk_lock(struct vm_area_struct *vma,
413 enum page_walk_lock walk_lock)
414{
415#ifdef CONFIG_PER_VMA_LOCK
416 switch (walk_lock) {
417 case PGWALK_WRLOCK:
418 vma_start_write(vma);
419 break;
420 case PGWALK_WRLOCK_VERIFY:
421 vma_assert_write_locked(vma);
422 break;
423 case PGWALK_RDLOCK:
424 /* PGWALK_RDLOCK is handled by process_mm_walk_lock */
425 break;
426 }
427#endif
428}
429
430/**
431 * walk_page_range - walk page table with caller specific callbacks
432 * @mm: mm_struct representing the target process of page table walk
433 * @start: start address of the virtual address range
434 * @end: end address of the virtual address range
435 * @ops: operation to call during the walk
436 * @private: private data for callbacks' usage
437 *
438 * Recursively walk the page table tree of the process represented by @mm
439 * within the virtual address range [@start, @end). During walking, we can do
440 * some caller-specific works for each entry, by setting up pmd_entry(),
441 * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
442 * callbacks, the associated entries/pages are just ignored.
443 * The return values of these callbacks are commonly defined like below:
444 *
445 * - 0 : succeeded to handle the current entry, and if you don't reach the
446 * end address yet, continue to walk.
447 * - >0 : succeeded to handle the current entry, and return to the caller
448 * with caller specific value.
449 * - <0 : failed to handle the current entry, and return to the caller
450 * with error code.
451 *
452 * Before starting to walk page table, some callers want to check whether
453 * they really want to walk over the current vma, typically by checking
454 * its vm_flags. walk_page_test() and @ops->test_walk() are used for this
455 * purpose.
456 *
457 * If operations need to be staged before and committed after a vma is walked,
458 * there are two callbacks, pre_vma() and post_vma(). Note that post_vma(),
459 * since it is intended to handle commit-type operations, can't return any
460 * errors.
461 *
462 * struct mm_walk keeps current values of some common data like vma and pmd,
463 * which are useful for the access from callbacks. If you want to pass some
464 * caller-specific data to callbacks, @private should be helpful.
465 *
466 * Locking:
467 * Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_lock,
468 * because these function traverse vma list and/or access to vma's data.
469 */
470int walk_page_range(struct mm_struct *mm, unsigned long start,
471 unsigned long end, const struct mm_walk_ops *ops,
472 void *private)
473{
474 int err = 0;
475 unsigned long next;
476 struct vm_area_struct *vma;
477 struct mm_walk walk = {
478 .ops = ops,
479 .mm = mm,
480 .private = private,
481 };
482
483 if (start >= end)
484 return -EINVAL;
485
486 if (!walk.mm)
487 return -EINVAL;
488
489 process_mm_walk_lock(walk.mm, ops->walk_lock);
490
491 vma = find_vma(walk.mm, start);
492 do {
493 if (!vma) { /* after the last vma */
494 walk.vma = NULL;
495 next = end;
496 if (ops->pte_hole)
497 err = ops->pte_hole(start, next, -1, &walk);
498 } else if (start < vma->vm_start) { /* outside vma */
499 walk.vma = NULL;
500 next = min(end, vma->vm_start);
501 if (ops->pte_hole)
502 err = ops->pte_hole(start, next, -1, &walk);
503 } else { /* inside vma */
504 process_vma_walk_lock(vma, ops->walk_lock);
505 walk.vma = vma;
506 next = min(end, vma->vm_end);
507 vma = find_vma(mm, vma->vm_end);
508
509 err = walk_page_test(start, next, &walk);
510 if (err > 0) {
511 /*
512 * positive return values are purely for
513 * controlling the pagewalk, so should never
514 * be passed to the callers.
515 */
516 err = 0;
517 continue;
518 }
519 if (err < 0)
520 break;
521 err = __walk_page_range(start, next, &walk);
522 }
523 if (err)
524 break;
525 } while (start = next, start < end);
526 return err;
527}
528
529/**
530 * walk_page_range_novma - walk a range of pagetables not backed by a vma
531 * @mm: mm_struct representing the target process of page table walk
532 * @start: start address of the virtual address range
533 * @end: end address of the virtual address range
534 * @ops: operation to call during the walk
535 * @pgd: pgd to walk if different from mm->pgd
536 * @private: private data for callbacks' usage
537 *
538 * Similar to walk_page_range() but can walk any page tables even if they are
539 * not backed by VMAs. Because 'unusual' entries may be walked this function
540 * will also not lock the PTEs for the pte_entry() callback. This is useful for
541 * walking the kernel pages tables or page tables for firmware.
542 *
543 * Note: Be careful to walk the kernel pages tables, the caller may be need to
544 * take other effective approache (mmap lock may be insufficient) to prevent
545 * the intermediate kernel page tables belonging to the specified address range
546 * from being freed (e.g. memory hot-remove).
547 */
548int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
549 unsigned long end, const struct mm_walk_ops *ops,
550 pgd_t *pgd,
551 void *private)
552{
553 struct mm_walk walk = {
554 .ops = ops,
555 .mm = mm,
556 .pgd = pgd,
557 .private = private,
558 .no_vma = true
559 };
560
561 if (start >= end || !walk.mm)
562 return -EINVAL;
563
564 /*
565 * 1) For walking the user virtual address space:
566 *
567 * The mmap lock protects the page walker from changes to the page
568 * tables during the walk. However a read lock is insufficient to
569 * protect those areas which don't have a VMA as munmap() detaches
570 * the VMAs before downgrading to a read lock and actually tearing
571 * down PTEs/page tables. In which case, the mmap write lock should
572 * be hold.
573 *
574 * 2) For walking the kernel virtual address space:
575 *
576 * The kernel intermediate page tables usually do not be freed, so
577 * the mmap map read lock is sufficient. But there are some exceptions.
578 * E.g. memory hot-remove. In which case, the mmap lock is insufficient
579 * to prevent the intermediate kernel pages tables belonging to the
580 * specified address range from being freed. The caller should take
581 * other actions to prevent this race.
582 */
583 if (mm == &init_mm)
584 mmap_assert_locked(walk.mm);
585 else
586 mmap_assert_write_locked(walk.mm);
587
588 return walk_pgd_range(start, end, &walk);
589}
590
591int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start,
592 unsigned long end, const struct mm_walk_ops *ops,
593 void *private)
594{
595 struct mm_walk walk = {
596 .ops = ops,
597 .mm = vma->vm_mm,
598 .vma = vma,
599 .private = private,
600 };
601
602 if (start >= end || !walk.mm)
603 return -EINVAL;
604 if (start < vma->vm_start || end > vma->vm_end)
605 return -EINVAL;
606
607 process_mm_walk_lock(walk.mm, ops->walk_lock);
608 process_vma_walk_lock(vma, ops->walk_lock);
609 return __walk_page_range(start, end, &walk);
610}
611
612int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
613 void *private)
614{
615 struct mm_walk walk = {
616 .ops = ops,
617 .mm = vma->vm_mm,
618 .vma = vma,
619 .private = private,
620 };
621
622 if (!walk.mm)
623 return -EINVAL;
624
625 process_mm_walk_lock(walk.mm, ops->walk_lock);
626 process_vma_walk_lock(vma, ops->walk_lock);
627 return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
628}
629
630/**
631 * walk_page_mapping - walk all memory areas mapped into a struct address_space.
632 * @mapping: Pointer to the struct address_space
633 * @first_index: First page offset in the address_space
634 * @nr: Number of incremental page offsets to cover
635 * @ops: operation to call during the walk
636 * @private: private data for callbacks' usage
637 *
638 * This function walks all memory areas mapped into a struct address_space.
639 * The walk is limited to only the given page-size index range, but if
640 * the index boundaries cross a huge page-table entry, that entry will be
641 * included.
642 *
643 * Also see walk_page_range() for additional information.
644 *
645 * Locking:
646 * This function can't require that the struct mm_struct::mmap_lock is held,
647 * since @mapping may be mapped by multiple processes. Instead
648 * @mapping->i_mmap_rwsem must be held. This might have implications in the
649 * callbacks, and it's up tho the caller to ensure that the
650 * struct mm_struct::mmap_lock is not needed.
651 *
652 * Also this means that a caller can't rely on the struct
653 * vm_area_struct::vm_flags to be constant across a call,
654 * except for immutable flags. Callers requiring this shouldn't use
655 * this function.
656 *
657 * Return: 0 on success, negative error code on failure, positive number on
658 * caller defined premature termination.
659 */
660int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
661 pgoff_t nr, const struct mm_walk_ops *ops,
662 void *private)
663{
664 struct mm_walk walk = {
665 .ops = ops,
666 .private = private,
667 };
668 struct vm_area_struct *vma;
669 pgoff_t vba, vea, cba, cea;
670 unsigned long start_addr, end_addr;
671 int err = 0;
672
673 lockdep_assert_held(&mapping->i_mmap_rwsem);
674 vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index,
675 first_index + nr - 1) {
676 /* Clip to the vma */
677 vba = vma->vm_pgoff;
678 vea = vba + vma_pages(vma);
679 cba = first_index;
680 cba = max(cba, vba);
681 cea = first_index + nr;
682 cea = min(cea, vea);
683
684 start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start;
685 end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start;
686 if (start_addr >= end_addr)
687 continue;
688
689 walk.vma = vma;
690 walk.mm = vma->vm_mm;
691
692 err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
693 if (err > 0) {
694 err = 0;
695 break;
696 } else if (err < 0)
697 break;
698
699 err = __walk_page_range(start_addr, end_addr, &walk);
700 if (err)
701 break;
702 }
703
704 return err;
705}