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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
7static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
8 struct mm_walk *walk)
9{
10 pte_t *pte;
11 int err = 0;
12 const struct mm_walk_ops *ops = walk->ops;
13
14 pte = pte_offset_map(pmd, addr);
15 for (;;) {
16 err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
17 if (err)
18 break;
19 addr += PAGE_SIZE;
20 if (addr == end)
21 break;
22 pte++;
23 }
24
25 pte_unmap(pte);
26 return err;
27}
28
29static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
30 struct mm_walk *walk)
31{
32 pmd_t *pmd;
33 unsigned long next;
34 const struct mm_walk_ops *ops = walk->ops;
35 int err = 0;
36
37 pmd = pmd_offset(pud, addr);
38 do {
39again:
40 next = pmd_addr_end(addr, end);
41 if (pmd_none(*pmd) || !walk->vma) {
42 if (ops->pte_hole)
43 err = ops->pte_hole(addr, next, walk);
44 if (err)
45 break;
46 continue;
47 }
48 /*
49 * This implies that each ->pmd_entry() handler
50 * needs to know about pmd_trans_huge() pmds
51 */
52 if (ops->pmd_entry)
53 err = ops->pmd_entry(pmd, addr, next, walk);
54 if (err)
55 break;
56
57 /*
58 * Check this here so we only break down trans_huge
59 * pages when we _need_ to
60 */
61 if (!ops->pte_entry)
62 continue;
63
64 split_huge_pmd(walk->vma, pmd, addr);
65 if (pmd_trans_unstable(pmd))
66 goto again;
67 err = walk_pte_range(pmd, addr, next, walk);
68 if (err)
69 break;
70 } while (pmd++, addr = next, addr != end);
71
72 return err;
73}
74
75static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
76 struct mm_walk *walk)
77{
78 pud_t *pud;
79 unsigned long next;
80 const struct mm_walk_ops *ops = walk->ops;
81 int err = 0;
82
83 pud = pud_offset(p4d, addr);
84 do {
85 again:
86 next = pud_addr_end(addr, end);
87 if (pud_none(*pud) || !walk->vma) {
88 if (ops->pte_hole)
89 err = ops->pte_hole(addr, next, walk);
90 if (err)
91 break;
92 continue;
93 }
94
95 if (ops->pud_entry) {
96 spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
97
98 if (ptl) {
99 err = ops->pud_entry(pud, addr, next, walk);
100 spin_unlock(ptl);
101 if (err)
102 break;
103 continue;
104 }
105 }
106
107 split_huge_pud(walk->vma, pud, addr);
108 if (pud_none(*pud))
109 goto again;
110
111 if (ops->pmd_entry || ops->pte_entry)
112 err = walk_pmd_range(pud, addr, next, walk);
113 if (err)
114 break;
115 } while (pud++, addr = next, addr != end);
116
117 return err;
118}
119
120static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
121 struct mm_walk *walk)
122{
123 p4d_t *p4d;
124 unsigned long next;
125 const struct mm_walk_ops *ops = walk->ops;
126 int err = 0;
127
128 p4d = p4d_offset(pgd, addr);
129 do {
130 next = p4d_addr_end(addr, end);
131 if (p4d_none_or_clear_bad(p4d)) {
132 if (ops->pte_hole)
133 err = ops->pte_hole(addr, next, walk);
134 if (err)
135 break;
136 continue;
137 }
138 if (ops->pmd_entry || ops->pte_entry)
139 err = walk_pud_range(p4d, addr, next, walk);
140 if (err)
141 break;
142 } while (p4d++, addr = next, addr != end);
143
144 return err;
145}
146
147static int walk_pgd_range(unsigned long addr, unsigned long end,
148 struct mm_walk *walk)
149{
150 pgd_t *pgd;
151 unsigned long next;
152 const struct mm_walk_ops *ops = walk->ops;
153 int err = 0;
154
155 pgd = pgd_offset(walk->mm, addr);
156 do {
157 next = pgd_addr_end(addr, end);
158 if (pgd_none_or_clear_bad(pgd)) {
159 if (ops->pte_hole)
160 err = ops->pte_hole(addr, next, walk);
161 if (err)
162 break;
163 continue;
164 }
165 if (ops->pmd_entry || ops->pte_entry)
166 err = walk_p4d_range(pgd, addr, next, walk);
167 if (err)
168 break;
169 } while (pgd++, addr = next, addr != end);
170
171 return err;
172}
173
174#ifdef CONFIG_HUGETLB_PAGE
175static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
176 unsigned long end)
177{
178 unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
179 return boundary < end ? boundary : end;
180}
181
182static int walk_hugetlb_range(unsigned long addr, unsigned long end,
183 struct mm_walk *walk)
184{
185 struct vm_area_struct *vma = walk->vma;
186 struct hstate *h = hstate_vma(vma);
187 unsigned long next;
188 unsigned long hmask = huge_page_mask(h);
189 unsigned long sz = huge_page_size(h);
190 pte_t *pte;
191 const struct mm_walk_ops *ops = walk->ops;
192 int err = 0;
193
194 do {
195 next = hugetlb_entry_end(h, addr, end);
196 pte = huge_pte_offset(walk->mm, addr & hmask, sz);
197
198 if (pte)
199 err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
200 else if (ops->pte_hole)
201 err = ops->pte_hole(addr, next, walk);
202
203 if (err)
204 break;
205 } while (addr = next, addr != end);
206
207 return err;
208}
209
210#else /* CONFIG_HUGETLB_PAGE */
211static int walk_hugetlb_range(unsigned long addr, unsigned long end,
212 struct mm_walk *walk)
213{
214 return 0;
215}
216
217#endif /* CONFIG_HUGETLB_PAGE */
218
219/*
220 * Decide whether we really walk over the current vma on [@start, @end)
221 * or skip it via the returned value. Return 0 if we do walk over the
222 * current vma, and return 1 if we skip the vma. Negative values means
223 * error, where we abort the current walk.
224 */
225static int walk_page_test(unsigned long start, unsigned long end,
226 struct mm_walk *walk)
227{
228 struct vm_area_struct *vma = walk->vma;
229 const struct mm_walk_ops *ops = walk->ops;
230
231 if (ops->test_walk)
232 return ops->test_walk(start, end, walk);
233
234 /*
235 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
236 * range, so we don't walk over it as we do for normal vmas. However,
237 * Some callers are interested in handling hole range and they don't
238 * want to just ignore any single address range. Such users certainly
239 * define their ->pte_hole() callbacks, so let's delegate them to handle
240 * vma(VM_PFNMAP).
241 */
242 if (vma->vm_flags & VM_PFNMAP) {
243 int err = 1;
244 if (ops->pte_hole)
245 err = ops->pte_hole(start, end, walk);
246 return err ? err : 1;
247 }
248 return 0;
249}
250
251static int __walk_page_range(unsigned long start, unsigned long end,
252 struct mm_walk *walk)
253{
254 int err = 0;
255 struct vm_area_struct *vma = walk->vma;
256
257 if (vma && is_vm_hugetlb_page(vma)) {
258 if (walk->ops->hugetlb_entry)
259 err = walk_hugetlb_range(start, end, walk);
260 } else
261 err = walk_pgd_range(start, end, walk);
262
263 return err;
264}
265
266/**
267 * walk_page_range - walk page table with caller specific callbacks
268 * @mm: mm_struct representing the target process of page table walk
269 * @start: start address of the virtual address range
270 * @end: end address of the virtual address range
271 * @ops: operation to call during the walk
272 * @private: private data for callbacks' usage
273 *
274 * Recursively walk the page table tree of the process represented by @mm
275 * within the virtual address range [@start, @end). During walking, we can do
276 * some caller-specific works for each entry, by setting up pmd_entry(),
277 * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
278 * callbacks, the associated entries/pages are just ignored.
279 * The return values of these callbacks are commonly defined like below:
280 *
281 * - 0 : succeeded to handle the current entry, and if you don't reach the
282 * end address yet, continue to walk.
283 * - >0 : succeeded to handle the current entry, and return to the caller
284 * with caller specific value.
285 * - <0 : failed to handle the current entry, and return to the caller
286 * with error code.
287 *
288 * Before starting to walk page table, some callers want to check whether
289 * they really want to walk over the current vma, typically by checking
290 * its vm_flags. walk_page_test() and @ops->test_walk() are used for this
291 * purpose.
292 *
293 * struct mm_walk keeps current values of some common data like vma and pmd,
294 * which are useful for the access from callbacks. If you want to pass some
295 * caller-specific data to callbacks, @private should be helpful.
296 *
297 * Locking:
298 * Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_sem,
299 * because these function traverse vma list and/or access to vma's data.
300 */
301int walk_page_range(struct mm_struct *mm, unsigned long start,
302 unsigned long end, const struct mm_walk_ops *ops,
303 void *private)
304{
305 int err = 0;
306 unsigned long next;
307 struct vm_area_struct *vma;
308 struct mm_walk walk = {
309 .ops = ops,
310 .mm = mm,
311 .private = private,
312 };
313
314 if (start >= end)
315 return -EINVAL;
316
317 if (!walk.mm)
318 return -EINVAL;
319
320 lockdep_assert_held(&walk.mm->mmap_sem);
321
322 vma = find_vma(walk.mm, start);
323 do {
324 if (!vma) { /* after the last vma */
325 walk.vma = NULL;
326 next = end;
327 } else if (start < vma->vm_start) { /* outside vma */
328 walk.vma = NULL;
329 next = min(end, vma->vm_start);
330 } else { /* inside vma */
331 walk.vma = vma;
332 next = min(end, vma->vm_end);
333 vma = vma->vm_next;
334
335 err = walk_page_test(start, next, &walk);
336 if (err > 0) {
337 /*
338 * positive return values are purely for
339 * controlling the pagewalk, so should never
340 * be passed to the callers.
341 */
342 err = 0;
343 continue;
344 }
345 if (err < 0)
346 break;
347 }
348 if (walk.vma || walk.ops->pte_hole)
349 err = __walk_page_range(start, next, &walk);
350 if (err)
351 break;
352 } while (start = next, start < end);
353 return err;
354}
355
356int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
357 void *private)
358{
359 struct mm_walk walk = {
360 .ops = ops,
361 .mm = vma->vm_mm,
362 .vma = vma,
363 .private = private,
364 };
365 int err;
366
367 if (!walk.mm)
368 return -EINVAL;
369
370 lockdep_assert_held(&walk.mm->mmap_sem);
371
372 err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
373 if (err > 0)
374 return 0;
375 if (err < 0)
376 return err;
377 return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
378}
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 pte = pte_offset_map(pmd, addr);
50 err = walk_pte_range_inner(pte, addr, end, walk);
51 pte_unmap(pte);
52 } else {
53 pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
54 err = walk_pte_range_inner(pte, addr, end, walk);
55 pte_unmap_unlock(pte, ptl);
56 }
57
58 return err;
59}
60
61#ifdef CONFIG_ARCH_HAS_HUGEPD
62static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr,
63 unsigned long end, struct mm_walk *walk, int pdshift)
64{
65 int err = 0;
66 const struct mm_walk_ops *ops = walk->ops;
67 int shift = hugepd_shift(*phpd);
68 int page_size = 1 << shift;
69
70 if (!ops->pte_entry)
71 return 0;
72
73 if (addr & (page_size - 1))
74 return 0;
75
76 for (;;) {
77 pte_t *pte;
78
79 spin_lock(&walk->mm->page_table_lock);
80 pte = hugepte_offset(*phpd, addr, pdshift);
81 err = ops->pte_entry(pte, addr, addr + page_size, walk);
82 spin_unlock(&walk->mm->page_table_lock);
83
84 if (err)
85 break;
86 if (addr >= end - page_size)
87 break;
88 addr += page_size;
89 }
90 return err;
91}
92#else
93static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr,
94 unsigned long end, struct mm_walk *walk, int pdshift)
95{
96 return 0;
97}
98#endif
99
100static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
101 struct mm_walk *walk)
102{
103 pmd_t *pmd;
104 unsigned long next;
105 const struct mm_walk_ops *ops = walk->ops;
106 int err = 0;
107 int depth = real_depth(3);
108
109 pmd = pmd_offset(pud, addr);
110 do {
111again:
112 next = pmd_addr_end(addr, end);
113 if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
114 if (ops->pte_hole)
115 err = ops->pte_hole(addr, next, depth, walk);
116 if (err)
117 break;
118 continue;
119 }
120
121 walk->action = ACTION_SUBTREE;
122
123 /*
124 * This implies that each ->pmd_entry() handler
125 * needs to know about pmd_trans_huge() pmds
126 */
127 if (ops->pmd_entry)
128 err = ops->pmd_entry(pmd, addr, next, walk);
129 if (err)
130 break;
131
132 if (walk->action == ACTION_AGAIN)
133 goto again;
134
135 /*
136 * Check this here so we only break down trans_huge
137 * pages when we _need_ to
138 */
139 if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) ||
140 walk->action == ACTION_CONTINUE ||
141 !(ops->pte_entry))
142 continue;
143
144 if (walk->vma) {
145 split_huge_pmd(walk->vma, pmd, addr);
146 if (pmd_trans_unstable(pmd))
147 goto again;
148 }
149
150 if (is_hugepd(__hugepd(pmd_val(*pmd))))
151 err = walk_hugepd_range((hugepd_t *)pmd, addr, next, walk, PMD_SHIFT);
152 else
153 err = walk_pte_range(pmd, addr, next, walk);
154 if (err)
155 break;
156 } while (pmd++, addr = next, addr != end);
157
158 return err;
159}
160
161static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
162 struct mm_walk *walk)
163{
164 pud_t *pud;
165 unsigned long next;
166 const struct mm_walk_ops *ops = walk->ops;
167 int err = 0;
168 int depth = real_depth(2);
169
170 pud = pud_offset(p4d, addr);
171 do {
172 again:
173 next = pud_addr_end(addr, end);
174 if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
175 if (ops->pte_hole)
176 err = ops->pte_hole(addr, next, depth, walk);
177 if (err)
178 break;
179 continue;
180 }
181
182 walk->action = ACTION_SUBTREE;
183
184 if (ops->pud_entry)
185 err = ops->pud_entry(pud, addr, next, walk);
186 if (err)
187 break;
188
189 if (walk->action == ACTION_AGAIN)
190 goto again;
191
192 if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) ||
193 walk->action == ACTION_CONTINUE ||
194 !(ops->pmd_entry || ops->pte_entry))
195 continue;
196
197 if (walk->vma)
198 split_huge_pud(walk->vma, pud, addr);
199 if (pud_none(*pud))
200 goto again;
201
202 if (is_hugepd(__hugepd(pud_val(*pud))))
203 err = walk_hugepd_range((hugepd_t *)pud, addr, next, walk, PUD_SHIFT);
204 else
205 err = walk_pmd_range(pud, addr, next, walk);
206 if (err)
207 break;
208 } while (pud++, addr = next, addr != end);
209
210 return err;
211}
212
213static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
214 struct mm_walk *walk)
215{
216 p4d_t *p4d;
217 unsigned long next;
218 const struct mm_walk_ops *ops = walk->ops;
219 int err = 0;
220 int depth = real_depth(1);
221
222 p4d = p4d_offset(pgd, addr);
223 do {
224 next = p4d_addr_end(addr, end);
225 if (p4d_none_or_clear_bad(p4d)) {
226 if (ops->pte_hole)
227 err = ops->pte_hole(addr, next, depth, walk);
228 if (err)
229 break;
230 continue;
231 }
232 if (ops->p4d_entry) {
233 err = ops->p4d_entry(p4d, addr, next, walk);
234 if (err)
235 break;
236 }
237 if (is_hugepd(__hugepd(p4d_val(*p4d))))
238 err = walk_hugepd_range((hugepd_t *)p4d, addr, next, walk, P4D_SHIFT);
239 else if (ops->pud_entry || ops->pmd_entry || ops->pte_entry)
240 err = walk_pud_range(p4d, addr, next, walk);
241 if (err)
242 break;
243 } while (p4d++, addr = next, addr != end);
244
245 return err;
246}
247
248static int walk_pgd_range(unsigned long addr, unsigned long end,
249 struct mm_walk *walk)
250{
251 pgd_t *pgd;
252 unsigned long next;
253 const struct mm_walk_ops *ops = walk->ops;
254 int err = 0;
255
256 if (walk->pgd)
257 pgd = walk->pgd + pgd_index(addr);
258 else
259 pgd = pgd_offset(walk->mm, addr);
260 do {
261 next = pgd_addr_end(addr, end);
262 if (pgd_none_or_clear_bad(pgd)) {
263 if (ops->pte_hole)
264 err = ops->pte_hole(addr, next, 0, walk);
265 if (err)
266 break;
267 continue;
268 }
269 if (ops->pgd_entry) {
270 err = ops->pgd_entry(pgd, addr, next, walk);
271 if (err)
272 break;
273 }
274 if (is_hugepd(__hugepd(pgd_val(*pgd))))
275 err = walk_hugepd_range((hugepd_t *)pgd, addr, next, walk, PGDIR_SHIFT);
276 else if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry || ops->pte_entry)
277 err = walk_p4d_range(pgd, addr, next, walk);
278 if (err)
279 break;
280 } while (pgd++, addr = next, addr != end);
281
282 return err;
283}
284
285#ifdef CONFIG_HUGETLB_PAGE
286static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
287 unsigned long end)
288{
289 unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
290 return boundary < end ? boundary : end;
291}
292
293static int walk_hugetlb_range(unsigned long addr, unsigned long end,
294 struct mm_walk *walk)
295{
296 struct vm_area_struct *vma = walk->vma;
297 struct hstate *h = hstate_vma(vma);
298 unsigned long next;
299 unsigned long hmask = huge_page_mask(h);
300 unsigned long sz = huge_page_size(h);
301 pte_t *pte;
302 const struct mm_walk_ops *ops = walk->ops;
303 int err = 0;
304
305 do {
306 next = hugetlb_entry_end(h, addr, end);
307 pte = huge_pte_offset(walk->mm, addr & hmask, sz);
308
309 if (pte)
310 err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
311 else if (ops->pte_hole)
312 err = ops->pte_hole(addr, next, -1, walk);
313
314 if (err)
315 break;
316 } while (addr = next, addr != end);
317
318 return err;
319}
320
321#else /* CONFIG_HUGETLB_PAGE */
322static int walk_hugetlb_range(unsigned long addr, unsigned long end,
323 struct mm_walk *walk)
324{
325 return 0;
326}
327
328#endif /* CONFIG_HUGETLB_PAGE */
329
330/*
331 * Decide whether we really walk over the current vma on [@start, @end)
332 * or skip it via the returned value. Return 0 if we do walk over the
333 * current vma, and return 1 if we skip the vma. Negative values means
334 * error, where we abort the current walk.
335 */
336static int walk_page_test(unsigned long start, unsigned long end,
337 struct mm_walk *walk)
338{
339 struct vm_area_struct *vma = walk->vma;
340 const struct mm_walk_ops *ops = walk->ops;
341
342 if (ops->test_walk)
343 return ops->test_walk(start, end, walk);
344
345 /*
346 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
347 * range, so we don't walk over it as we do for normal vmas. However,
348 * Some callers are interested in handling hole range and they don't
349 * want to just ignore any single address range. Such users certainly
350 * define their ->pte_hole() callbacks, so let's delegate them to handle
351 * vma(VM_PFNMAP).
352 */
353 if (vma->vm_flags & VM_PFNMAP) {
354 int err = 1;
355 if (ops->pte_hole)
356 err = ops->pte_hole(start, end, -1, walk);
357 return err ? err : 1;
358 }
359 return 0;
360}
361
362static int __walk_page_range(unsigned long start, unsigned long end,
363 struct mm_walk *walk)
364{
365 int err = 0;
366 struct vm_area_struct *vma = walk->vma;
367 const struct mm_walk_ops *ops = walk->ops;
368
369 if (vma && ops->pre_vma) {
370 err = ops->pre_vma(start, end, walk);
371 if (err)
372 return err;
373 }
374
375 if (vma && is_vm_hugetlb_page(vma)) {
376 if (ops->hugetlb_entry)
377 err = walk_hugetlb_range(start, end, walk);
378 } else
379 err = walk_pgd_range(start, end, walk);
380
381 if (vma && ops->post_vma)
382 ops->post_vma(walk);
383
384 return err;
385}
386
387/**
388 * walk_page_range - walk page table with caller specific callbacks
389 * @mm: mm_struct representing the target process of page table walk
390 * @start: start address of the virtual address range
391 * @end: end address of the virtual address range
392 * @ops: operation to call during the walk
393 * @private: private data for callbacks' usage
394 *
395 * Recursively walk the page table tree of the process represented by @mm
396 * within the virtual address range [@start, @end). During walking, we can do
397 * some caller-specific works for each entry, by setting up pmd_entry(),
398 * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
399 * callbacks, the associated entries/pages are just ignored.
400 * The return values of these callbacks are commonly defined like below:
401 *
402 * - 0 : succeeded to handle the current entry, and if you don't reach the
403 * end address yet, continue to walk.
404 * - >0 : succeeded to handle the current entry, and return to the caller
405 * with caller specific value.
406 * - <0 : failed to handle the current entry, and return to the caller
407 * with error code.
408 *
409 * Before starting to walk page table, some callers want to check whether
410 * they really want to walk over the current vma, typically by checking
411 * its vm_flags. walk_page_test() and @ops->test_walk() are used for this
412 * purpose.
413 *
414 * If operations need to be staged before and committed after a vma is walked,
415 * there are two callbacks, pre_vma() and post_vma(). Note that post_vma(),
416 * since it is intended to handle commit-type operations, can't return any
417 * errors.
418 *
419 * struct mm_walk keeps current values of some common data like vma and pmd,
420 * which are useful for the access from callbacks. If you want to pass some
421 * caller-specific data to callbacks, @private should be helpful.
422 *
423 * Locking:
424 * Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_lock,
425 * because these function traverse vma list and/or access to vma's data.
426 */
427int walk_page_range(struct mm_struct *mm, unsigned long start,
428 unsigned long end, const struct mm_walk_ops *ops,
429 void *private)
430{
431 int err = 0;
432 unsigned long next;
433 struct vm_area_struct *vma;
434 struct mm_walk walk = {
435 .ops = ops,
436 .mm = mm,
437 .private = private,
438 };
439
440 if (start >= end)
441 return -EINVAL;
442
443 if (!walk.mm)
444 return -EINVAL;
445
446 mmap_assert_locked(walk.mm);
447
448 vma = find_vma(walk.mm, start);
449 do {
450 if (!vma) { /* after the last vma */
451 walk.vma = NULL;
452 next = end;
453 } else if (start < vma->vm_start) { /* outside vma */
454 walk.vma = NULL;
455 next = min(end, vma->vm_start);
456 } else { /* inside vma */
457 walk.vma = vma;
458 next = min(end, vma->vm_end);
459 vma = vma->vm_next;
460
461 err = walk_page_test(start, next, &walk);
462 if (err > 0) {
463 /*
464 * positive return values are purely for
465 * controlling the pagewalk, so should never
466 * be passed to the callers.
467 */
468 err = 0;
469 continue;
470 }
471 if (err < 0)
472 break;
473 }
474 if (walk.vma || walk.ops->pte_hole)
475 err = __walk_page_range(start, next, &walk);
476 if (err)
477 break;
478 } while (start = next, start < end);
479 return err;
480}
481
482/*
483 * Similar to walk_page_range() but can walk any page tables even if they are
484 * not backed by VMAs. Because 'unusual' entries may be walked this function
485 * will also not lock the PTEs for the pte_entry() callback. This is useful for
486 * walking the kernel pages tables or page tables for firmware.
487 */
488int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
489 unsigned long end, const struct mm_walk_ops *ops,
490 pgd_t *pgd,
491 void *private)
492{
493 struct mm_walk walk = {
494 .ops = ops,
495 .mm = mm,
496 .pgd = pgd,
497 .private = private,
498 .no_vma = true
499 };
500
501 if (start >= end || !walk.mm)
502 return -EINVAL;
503
504 mmap_assert_locked(walk.mm);
505
506 return __walk_page_range(start, end, &walk);
507}
508
509int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
510 void *private)
511{
512 struct mm_walk walk = {
513 .ops = ops,
514 .mm = vma->vm_mm,
515 .vma = vma,
516 .private = private,
517 };
518 int err;
519
520 if (!walk.mm)
521 return -EINVAL;
522
523 mmap_assert_locked(walk.mm);
524
525 err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
526 if (err > 0)
527 return 0;
528 if (err < 0)
529 return err;
530 return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
531}
532
533/**
534 * walk_page_mapping - walk all memory areas mapped into a struct address_space.
535 * @mapping: Pointer to the struct address_space
536 * @first_index: First page offset in the address_space
537 * @nr: Number of incremental page offsets to cover
538 * @ops: operation to call during the walk
539 * @private: private data for callbacks' usage
540 *
541 * This function walks all memory areas mapped into a struct address_space.
542 * The walk is limited to only the given page-size index range, but if
543 * the index boundaries cross a huge page-table entry, that entry will be
544 * included.
545 *
546 * Also see walk_page_range() for additional information.
547 *
548 * Locking:
549 * This function can't require that the struct mm_struct::mmap_lock is held,
550 * since @mapping may be mapped by multiple processes. Instead
551 * @mapping->i_mmap_rwsem must be held. This might have implications in the
552 * callbacks, and it's up tho the caller to ensure that the
553 * struct mm_struct::mmap_lock is not needed.
554 *
555 * Also this means that a caller can't rely on the struct
556 * vm_area_struct::vm_flags to be constant across a call,
557 * except for immutable flags. Callers requiring this shouldn't use
558 * this function.
559 *
560 * Return: 0 on success, negative error code on failure, positive number on
561 * caller defined premature termination.
562 */
563int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
564 pgoff_t nr, const struct mm_walk_ops *ops,
565 void *private)
566{
567 struct mm_walk walk = {
568 .ops = ops,
569 .private = private,
570 };
571 struct vm_area_struct *vma;
572 pgoff_t vba, vea, cba, cea;
573 unsigned long start_addr, end_addr;
574 int err = 0;
575
576 lockdep_assert_held(&mapping->i_mmap_rwsem);
577 vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index,
578 first_index + nr - 1) {
579 /* Clip to the vma */
580 vba = vma->vm_pgoff;
581 vea = vba + vma_pages(vma);
582 cba = first_index;
583 cba = max(cba, vba);
584 cea = first_index + nr;
585 cea = min(cea, vea);
586
587 start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start;
588 end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start;
589 if (start_addr >= end_addr)
590 continue;
591
592 walk.vma = vma;
593 walk.mm = vma->vm_mm;
594
595 err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
596 if (err > 0) {
597 err = 0;
598 break;
599 } else if (err < 0)
600 break;
601
602 err = __walk_page_range(start_addr, end_addr, &walk);
603 if (err)
604 break;
605 }
606
607 return err;
608}