rseq: Use get_user/put_user rather than __get_user/__put_user
[linux-2.6-microblaze.git] / mm / pagewalk.c
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/mm.h>
3 #include <linux/highmem.h>
4 #include <linux/sched.h>
5 #include <linux/hugetlb.h>
6
7 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
13         pte = pte_offset_map(pmd, addr);
14         for (;;) {
15                 err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
16                 if (err)
17                        break;
18                 addr += PAGE_SIZE;
19                 if (addr == end)
20                         break;
21                 pte++;
22         }
23
24         pte_unmap(pte);
25         return err;
26 }
27
28 static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
29                           struct mm_walk *walk)
30 {
31         pmd_t *pmd;
32         unsigned long next;
33         int err = 0;
34
35         pmd = pmd_offset(pud, addr);
36         do {
37 again:
38                 next = pmd_addr_end(addr, end);
39                 if (pmd_none(*pmd) || !walk->vma) {
40                         if (walk->pte_hole)
41                                 err = walk->pte_hole(addr, next, walk);
42                         if (err)
43                                 break;
44                         continue;
45                 }
46                 /*
47                  * This implies that each ->pmd_entry() handler
48                  * needs to know about pmd_trans_huge() pmds
49                  */
50                 if (walk->pmd_entry)
51                         err = walk->pmd_entry(pmd, addr, next, walk);
52                 if (err)
53                         break;
54
55                 /*
56                  * Check this here so we only break down trans_huge
57                  * pages when we _need_ to
58                  */
59                 if (!walk->pte_entry)
60                         continue;
61
62                 split_huge_pmd(walk->vma, pmd, addr);
63                 if (pmd_trans_unstable(pmd))
64                         goto again;
65                 err = walk_pte_range(pmd, addr, next, walk);
66                 if (err)
67                         break;
68         } while (pmd++, addr = next, addr != end);
69
70         return err;
71 }
72
73 static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
74                           struct mm_walk *walk)
75 {
76         pud_t *pud;
77         unsigned long next;
78         int err = 0;
79
80         pud = pud_offset(p4d, addr);
81         do {
82  again:
83                 next = pud_addr_end(addr, end);
84                 if (pud_none(*pud) || !walk->vma) {
85                         if (walk->pte_hole)
86                                 err = walk->pte_hole(addr, next, walk);
87                         if (err)
88                                 break;
89                         continue;
90                 }
91
92                 if (walk->pud_entry) {
93                         spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
94
95                         if (ptl) {
96                                 err = walk->pud_entry(pud, addr, next, walk);
97                                 spin_unlock(ptl);
98                                 if (err)
99                                         break;
100                                 continue;
101                         }
102                 }
103
104                 split_huge_pud(walk->vma, pud, addr);
105                 if (pud_none(*pud))
106                         goto again;
107
108                 if (walk->pmd_entry || walk->pte_entry)
109                         err = walk_pmd_range(pud, addr, next, walk);
110                 if (err)
111                         break;
112         } while (pud++, addr = next, addr != end);
113
114         return err;
115 }
116
117 static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
118                           struct mm_walk *walk)
119 {
120         p4d_t *p4d;
121         unsigned long next;
122         int err = 0;
123
124         p4d = p4d_offset(pgd, addr);
125         do {
126                 next = p4d_addr_end(addr, end);
127                 if (p4d_none_or_clear_bad(p4d)) {
128                         if (walk->pte_hole)
129                                 err = walk->pte_hole(addr, next, walk);
130                         if (err)
131                                 break;
132                         continue;
133                 }
134                 if (walk->pmd_entry || walk->pte_entry)
135                         err = walk_pud_range(p4d, addr, next, walk);
136                 if (err)
137                         break;
138         } while (p4d++, addr = next, addr != end);
139
140         return err;
141 }
142
143 static int walk_pgd_range(unsigned long addr, unsigned long end,
144                           struct mm_walk *walk)
145 {
146         pgd_t *pgd;
147         unsigned long next;
148         int err = 0;
149
150         pgd = pgd_offset(walk->mm, addr);
151         do {
152                 next = pgd_addr_end(addr, end);
153                 if (pgd_none_or_clear_bad(pgd)) {
154                         if (walk->pte_hole)
155                                 err = walk->pte_hole(addr, next, walk);
156                         if (err)
157                                 break;
158                         continue;
159                 }
160                 if (walk->pmd_entry || walk->pte_entry)
161                         err = walk_p4d_range(pgd, addr, next, walk);
162                 if (err)
163                         break;
164         } while (pgd++, addr = next, addr != end);
165
166         return err;
167 }
168
169 #ifdef CONFIG_HUGETLB_PAGE
170 static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
171                                        unsigned long end)
172 {
173         unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
174         return boundary < end ? boundary : end;
175 }
176
177 static int walk_hugetlb_range(unsigned long addr, unsigned long end,
178                               struct mm_walk *walk)
179 {
180         struct vm_area_struct *vma = walk->vma;
181         struct hstate *h = hstate_vma(vma);
182         unsigned long next;
183         unsigned long hmask = huge_page_mask(h);
184         unsigned long sz = huge_page_size(h);
185         pte_t *pte;
186         int err = 0;
187
188         do {
189                 next = hugetlb_entry_end(h, addr, end);
190                 pte = huge_pte_offset(walk->mm, addr & hmask, sz);
191
192                 if (pte)
193                         err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
194                 else if (walk->pte_hole)
195                         err = walk->pte_hole(addr, next, walk);
196
197                 if (err)
198                         break;
199         } while (addr = next, addr != end);
200
201         return err;
202 }
203
204 #else /* CONFIG_HUGETLB_PAGE */
205 static int walk_hugetlb_range(unsigned long addr, unsigned long end,
206                               struct mm_walk *walk)
207 {
208         return 0;
209 }
210
211 #endif /* CONFIG_HUGETLB_PAGE */
212
213 /*
214  * Decide whether we really walk over the current vma on [@start, @end)
215  * or skip it via the returned value. Return 0 if we do walk over the
216  * current vma, and return 1 if we skip the vma. Negative values means
217  * error, where we abort the current walk.
218  */
219 static int walk_page_test(unsigned long start, unsigned long end,
220                         struct mm_walk *walk)
221 {
222         struct vm_area_struct *vma = walk->vma;
223
224         if (walk->test_walk)
225                 return walk->test_walk(start, end, walk);
226
227         /*
228          * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
229          * range, so we don't walk over it as we do for normal vmas. However,
230          * Some callers are interested in handling hole range and they don't
231          * want to just ignore any single address range. Such users certainly
232          * define their ->pte_hole() callbacks, so let's delegate them to handle
233          * vma(VM_PFNMAP).
234          */
235         if (vma->vm_flags & VM_PFNMAP) {
236                 int err = 1;
237                 if (walk->pte_hole)
238                         err = walk->pte_hole(start, end, walk);
239                 return err ? err : 1;
240         }
241         return 0;
242 }
243
244 static int __walk_page_range(unsigned long start, unsigned long end,
245                         struct mm_walk *walk)
246 {
247         int err = 0;
248         struct vm_area_struct *vma = walk->vma;
249
250         if (vma && is_vm_hugetlb_page(vma)) {
251                 if (walk->hugetlb_entry)
252                         err = walk_hugetlb_range(start, end, walk);
253         } else
254                 err = walk_pgd_range(start, end, walk);
255
256         return err;
257 }
258
259 /**
260  * walk_page_range - walk page table with caller specific callbacks
261  * @start: start address of the virtual address range
262  * @end: end address of the virtual address range
263  * @walk: mm_walk structure defining the callbacks and the target address space
264  *
265  * Recursively walk the page table tree of the process represented by @walk->mm
266  * within the virtual address range [@start, @end). During walking, we can do
267  * some caller-specific works for each entry, by setting up pmd_entry(),
268  * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
269  * callbacks, the associated entries/pages are just ignored.
270  * The return values of these callbacks are commonly defined like below:
271  *
272  *  - 0  : succeeded to handle the current entry, and if you don't reach the
273  *         end address yet, continue to walk.
274  *  - >0 : succeeded to handle the current entry, and return to the caller
275  *         with caller specific value.
276  *  - <0 : failed to handle the current entry, and return to the caller
277  *         with error code.
278  *
279  * Before starting to walk page table, some callers want to check whether
280  * they really want to walk over the current vma, typically by checking
281  * its vm_flags. walk_page_test() and @walk->test_walk() are used for this
282  * purpose.
283  *
284  * struct mm_walk keeps current values of some common data like vma and pmd,
285  * which are useful for the access from callbacks. If you want to pass some
286  * caller-specific data to callbacks, @walk->private should be helpful.
287  *
288  * Locking:
289  *   Callers of walk_page_range() and walk_page_vma() should hold
290  *   @walk->mm->mmap_sem, because these function traverse vma list and/or
291  *   access to vma's data.
292  */
293 int walk_page_range(unsigned long start, unsigned long end,
294                     struct mm_walk *walk)
295 {
296         int err = 0;
297         unsigned long next;
298         struct vm_area_struct *vma;
299
300         if (start >= end)
301                 return -EINVAL;
302
303         if (!walk->mm)
304                 return -EINVAL;
305
306         VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
307
308         vma = find_vma(walk->mm, start);
309         do {
310                 if (!vma) { /* after the last vma */
311                         walk->vma = NULL;
312                         next = end;
313                 } else if (start < vma->vm_start) { /* outside vma */
314                         walk->vma = NULL;
315                         next = min(end, vma->vm_start);
316                 } else { /* inside vma */
317                         walk->vma = vma;
318                         next = min(end, vma->vm_end);
319                         vma = vma->vm_next;
320
321                         err = walk_page_test(start, next, walk);
322                         if (err > 0) {
323                                 /*
324                                  * positive return values are purely for
325                                  * controlling the pagewalk, so should never
326                                  * be passed to the callers.
327                                  */
328                                 err = 0;
329                                 continue;
330                         }
331                         if (err < 0)
332                                 break;
333                 }
334                 if (walk->vma || walk->pte_hole)
335                         err = __walk_page_range(start, next, walk);
336                 if (err)
337                         break;
338         } while (start = next, start < end);
339         return err;
340 }
341
342 int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
343 {
344         int err;
345
346         if (!walk->mm)
347                 return -EINVAL;
348
349         VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
350         VM_BUG_ON(!vma);
351         walk->vma = vma;
352         err = walk_page_test(vma->vm_start, vma->vm_end, walk);
353         if (err > 0)
354                 return 0;
355         if (err < 0)
356                 return err;
357         return __walk_page_range(vma->vm_start, vma->vm_end, walk);
358 }