Branch data Line data Source code
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 : 0 : static 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 : 0 : const struct mm_walk_ops *ops = walk->ops;
13 : :
14 : 0 : pte = pte_offset_map(pmd, addr);
15 : : for (;;) {
16 : 0 : err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
17 [ # # ]: 0 : if (err)
18 : : break;
19 : : addr += PAGE_SIZE;
20 [ # # ]: 0 : if (addr == end)
21 : : break;
22 : 0 : pte++;
23 : 0 : }
24 : :
25 : : pte_unmap(pte);
26 : 0 : return err;
27 : : }
28 : :
29 : 0 : static 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 : 0 : const struct mm_walk_ops *ops = walk->ops;
35 : : int err = 0;
36 : :
37 : : pmd = pmd_offset(pud, addr);
38 : : do {
39 : : again:
40 : : next = pmd_addr_end(addr, end);
41 [ # # # # ]: 0 : if (pmd_none(*pmd) || !walk->vma) {
42 [ # # ]: 0 : if (ops->pte_hole)
43 : 0 : err = ops->pte_hole(addr, next, walk);
44 [ # # ]: 0 : if (err)
45 : : break;
46 : 0 : continue;
47 : : }
48 : : /*
49 : : * This implies that each ->pmd_entry() handler
50 : : * needs to know about pmd_trans_huge() pmds
51 : : */
52 [ # # ]: 0 : if (ops->pmd_entry)
53 : 0 : err = ops->pmd_entry(pmd, addr, next, walk);
54 [ # # ]: 0 : 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 [ # # ]: 0 : if (!ops->pte_entry)
62 : 0 : continue;
63 : :
64 : : split_huge_pmd(walk->vma, pmd, addr);
65 : : if (pmd_trans_unstable(pmd))
66 : : goto again;
67 : 0 : err = walk_pte_range(pmd, addr, next, walk);
68 : : if (err)
69 : : break;
70 : : } while (pmd++, addr = next, addr != end);
71 : :
72 : 0 : return err;
73 : : }
74 : :
75 : 0 : static 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 : 0 : 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 [ # # ]: 0 : if (pud_none(*pud) || !walk->vma) {
88 [ # # ]: 0 : if (ops->pte_hole)
89 : 0 : err = ops->pte_hole(addr, next, walk);
90 [ # # ]: 0 : if (err)
91 : : break;
92 : 0 : 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 [ # # # # ]: 0 : if (ops->pmd_entry || ops->pte_entry)
112 : 0 : err = walk_pmd_range(pud, addr, next, walk);
113 : : if (err)
114 : : break;
115 : : } while (pud++, addr = next, addr != end);
116 : :
117 : 0 : return err;
118 : : }
119 : :
120 : 0 : static 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 : 0 : 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 [ # # # # ]: 0 : if (ops->pmd_entry || ops->pte_entry)
139 : 0 : err = walk_pud_range(p4d, addr, next, walk);
140 : : if (err)
141 : : break;
142 : : } while (p4d++, addr = next, addr != end);
143 : :
144 : 0 : return err;
145 : : }
146 : :
147 : 0 : static 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 : 0 : const struct mm_walk_ops *ops = walk->ops;
153 : : int err = 0;
154 : :
155 : 0 : pgd = pgd_offset(walk->mm, addr);
156 : : do {
157 [ # # ]: 0 : 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 [ # # # # ]: 0 : if (ops->pmd_entry || ops->pte_entry)
166 : 0 : err = walk_p4d_range(pgd, addr, next, walk);
167 [ # # ]: 0 : if (err)
168 : : break;
169 [ # # ]: 0 : } while (pgd++, addr = next, addr != end);
170 : :
171 : 0 : return err;
172 : : }
173 : :
174 : : #ifdef CONFIG_HUGETLB_PAGE
175 : : static 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 : :
182 : : static 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 */
211 : : static 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 : : */
225 : 0 : static int walk_page_test(unsigned long start, unsigned long end,
226 : : struct mm_walk *walk)
227 : : {
228 : 0 : struct vm_area_struct *vma = walk->vma;
229 : 0 : const struct mm_walk_ops *ops = walk->ops;
230 : :
231 [ # # ]: 0 : if (ops->test_walk)
232 : 0 : 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 [ # # ]: 0 : if (vma->vm_flags & VM_PFNMAP) {
243 : : int err = 1;
244 [ # # ]: 0 : if (ops->pte_hole)
245 : 0 : err = ops->pte_hole(start, end, walk);
246 [ # # ]: 0 : return err ? err : 1;
247 : : }
248 : : return 0;
249 : : }
250 : :
251 : : static 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 : 0 : 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 : : */
301 : 0 : int 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 : 0 : struct mm_walk walk = {
309 : : .ops = ops,
310 : : .mm = mm,
311 : : .private = private,
312 : : };
313 : :
314 [ # # ]: 0 : if (start >= end)
315 : : return -EINVAL;
316 : :
317 [ # # ]: 0 : if (!walk.mm)
318 : : return -EINVAL;
319 : :
320 : : lockdep_assert_held(&walk.mm->mmap_sem);
321 : :
322 : 0 : vma = find_vma(walk.mm, start);
323 : : do {
324 [ # # ]: 0 : if (!vma) { /* after the last vma */
325 : 0 : walk.vma = NULL;
326 : : next = end;
327 [ # # ]: 0 : } else if (start < vma->vm_start) { /* outside vma */
328 : 0 : walk.vma = NULL;
329 : 0 : next = min(end, vma->vm_start);
330 : : } else { /* inside vma */
331 : 0 : walk.vma = vma;
332 : 0 : next = min(end, vma->vm_end);
333 : 0 : vma = vma->vm_next;
334 : :
335 : 0 : err = walk_page_test(start, next, &walk);
336 [ # # ]: 0 : 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 : 0 : continue;
344 : : }
345 [ # # ]: 0 : if (err < 0)
346 : : break;
347 : : }
348 [ # # # # ]: 0 : if (walk.vma || walk.ops->pte_hole)
349 : : err = __walk_page_range(start, next, &walk);
350 [ # # ]: 0 : if (err)
351 : : break;
352 [ # # ]: 0 : } while (start = next, start < end);
353 : 0 : return err;
354 : : }
355 : :
356 : 0 : int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
357 : : void *private)
358 : : {
359 : 0 : struct mm_walk walk = {
360 : : .ops = ops,
361 : 0 : .mm = vma->vm_mm,
362 : : .vma = vma,
363 : : .private = private,
364 : : };
365 : : int err;
366 : :
367 [ # # ]: 0 : if (!walk.mm)
368 : : return -EINVAL;
369 : :
370 : : lockdep_assert_held(&walk.mm->mmap_sem);
371 : :
372 : 0 : err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
373 [ # # ]: 0 : if (err > 0)
374 : : return 0;
375 [ # # ]: 0 : if (err < 0)
376 : : return err;
377 : 0 : return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
378 : : }
|
