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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
ace71a19 KS |
2 | #include <linux/mm.h> |
3 | #include <linux/rmap.h> | |
4 | #include <linux/hugetlb.h> | |
5 | #include <linux/swap.h> | |
6 | #include <linux/swapops.h> | |
7 | ||
8 | #include "internal.h" | |
9 | ||
ace71a19 KS |
10 | static inline bool not_found(struct page_vma_mapped_walk *pvmw) |
11 | { | |
12 | page_vma_mapped_walk_done(pvmw); | |
13 | return false; | |
14 | } | |
15 | ||
16 | static bool map_pte(struct page_vma_mapped_walk *pvmw) | |
17 | { | |
18 | pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address); | |
19 | if (!(pvmw->flags & PVMW_SYNC)) { | |
20 | if (pvmw->flags & PVMW_MIGRATION) { | |
21 | if (!is_swap_pte(*pvmw->pte)) | |
22 | return false; | |
23 | } else { | |
aab8d052 RC |
24 | /* |
25 | * We get here when we are trying to unmap a private | |
26 | * device page from the process address space. Such | |
27 | * page is not CPU accessible and thus is mapped as | |
28 | * a special swap entry, nonetheless it still does | |
29 | * count as a valid regular mapping for the page (and | |
30 | * is accounted as such in page maps count). | |
31 | * | |
32 | * So handle this special case as if it was a normal | |
33 | * page mapping ie lock CPU page table and returns | |
34 | * true. | |
35 | * | |
36 | * For more details on device private memory see HMM | |
37 | * (include/linux/hmm.h or mm/hmm.c). | |
38 | */ | |
39 | if (is_swap_pte(*pvmw->pte)) { | |
40 | swp_entry_t entry; | |
41 | ||
42 | /* Handle un-addressable ZONE_DEVICE memory */ | |
43 | entry = pte_to_swp_entry(*pvmw->pte); | |
b756a3b5 AP |
44 | if (!is_device_private_entry(entry) && |
45 | !is_device_exclusive_entry(entry)) | |
aab8d052 RC |
46 | return false; |
47 | } else if (!pte_present(*pvmw->pte)) | |
ace71a19 KS |
48 | return false; |
49 | } | |
50 | } | |
51 | pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd); | |
52 | spin_lock(pvmw->ptl); | |
53 | return true; | |
54 | } | |
55 | ||
0d665e7b KS |
56 | /** |
57 | * check_pte - check if @pvmw->page is mapped at the @pvmw->pte | |
777f303c | 58 | * @pvmw: page_vma_mapped_walk struct, includes a pair pte and page for checking |
0d665e7b KS |
59 | * |
60 | * page_vma_mapped_walk() found a place where @pvmw->page is *potentially* | |
61 | * mapped. check_pte() has to validate this. | |
62 | * | |
777f303c AS |
63 | * pvmw->pte may point to empty PTE, swap PTE or PTE pointing to |
64 | * arbitrary page. | |
0d665e7b KS |
65 | * |
66 | * If PVMW_MIGRATION flag is set, returns true if @pvmw->pte contains migration | |
67 | * entry that points to @pvmw->page or any subpage in case of THP. | |
68 | * | |
777f303c AS |
69 | * If PVMW_MIGRATION flag is not set, returns true if pvmw->pte points to |
70 | * pvmw->page or any subpage in case of THP. | |
0d665e7b KS |
71 | * |
72 | * Otherwise, return false. | |
73 | * | |
74 | */ | |
ace71a19 KS |
75 | static bool check_pte(struct page_vma_mapped_walk *pvmw) |
76 | { | |
0d665e7b KS |
77 | unsigned long pfn; |
78 | ||
ace71a19 | 79 | if (pvmw->flags & PVMW_MIGRATION) { |
ace71a19 KS |
80 | swp_entry_t entry; |
81 | if (!is_swap_pte(*pvmw->pte)) | |
82 | return false; | |
83 | entry = pte_to_swp_entry(*pvmw->pte); | |
a5430dda | 84 | |
b756a3b5 AP |
85 | if (!is_migration_entry(entry) && |
86 | !is_device_exclusive_entry(entry)) | |
ace71a19 | 87 | return false; |
a5430dda | 88 | |
0d206b5d | 89 | pfn = swp_offset_pfn(entry); |
0d665e7b KS |
90 | } else if (is_swap_pte(*pvmw->pte)) { |
91 | swp_entry_t entry; | |
a5430dda | 92 | |
0d665e7b KS |
93 | /* Handle un-addressable ZONE_DEVICE memory */ |
94 | entry = pte_to_swp_entry(*pvmw->pte); | |
b756a3b5 AP |
95 | if (!is_device_private_entry(entry) && |
96 | !is_device_exclusive_entry(entry)) | |
ace71a19 KS |
97 | return false; |
98 | ||
0d206b5d | 99 | pfn = swp_offset_pfn(entry); |
0d665e7b KS |
100 | } else { |
101 | if (!pte_present(*pvmw->pte)) | |
ace71a19 | 102 | return false; |
0d665e7b KS |
103 | |
104 | pfn = pte_pfn(*pvmw->pte); | |
ace71a19 KS |
105 | } |
106 | ||
2aff7a47 MWO |
107 | return (pfn - pvmw->pfn) < pvmw->nr_pages; |
108 | } | |
109 | ||
110 | /* Returns true if the two ranges overlap. Careful to not overflow. */ | |
111 | static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw) | |
112 | { | |
113 | if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn) | |
114 | return false; | |
115 | if (pfn > pvmw->pfn + pvmw->nr_pages - 1) | |
116 | return false; | |
117 | return true; | |
ace71a19 KS |
118 | } |
119 | ||
a9a7504d HD |
120 | static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) |
121 | { | |
122 | pvmw->address = (pvmw->address + size) & ~(size - 1); | |
123 | if (!pvmw->address) | |
124 | pvmw->address = ULONG_MAX; | |
125 | } | |
126 | ||
ace71a19 | 127 | /** |
2aff7a47 | 128 | * page_vma_mapped_walk - check if @pvmw->pfn is mapped in @pvmw->vma at |
ace71a19 KS |
129 | * @pvmw->address |
130 | * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags | |
131 | * must be set. pmd, pte and ptl must be NULL. | |
132 | * | |
133 | * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point | |
134 | * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is | |
135 | * adjusted if needed (for PTE-mapped THPs). | |
136 | * | |
137 | * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page | |
138 | * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in | |
139 | * a loop to find all PTEs that map the THP. | |
140 | * | |
141 | * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry | |
142 | * regardless of which page table level the page is mapped at. @pvmw->pmd is | |
143 | * NULL. | |
144 | * | |
baf2f90b | 145 | * Returns false if there are no more page table entries for the page in |
ace71a19 KS |
146 | * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped. |
147 | * | |
148 | * If you need to stop the walk before page_vma_mapped_walk() returned false, | |
149 | * use page_vma_mapped_walk_done(). It will do the housekeeping. | |
150 | */ | |
151 | bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) | |
152 | { | |
2aff7a47 MWO |
153 | struct vm_area_struct *vma = pvmw->vma; |
154 | struct mm_struct *mm = vma->vm_mm; | |
47446630 | 155 | unsigned long end; |
ace71a19 | 156 | pgd_t *pgd; |
c2febafc | 157 | p4d_t *p4d; |
ace71a19 | 158 | pud_t *pud; |
a7b10095 | 159 | pmd_t pmde; |
ace71a19 KS |
160 | |
161 | /* The only possible pmd mapping has been handled on last iteration */ | |
162 | if (pvmw->pmd && !pvmw->pte) | |
163 | return not_found(pvmw); | |
164 | ||
2aff7a47 | 165 | if (unlikely(is_vm_hugetlb_page(vma))) { |
98ea0259 | 166 | struct hstate *hstate = hstate_vma(vma); |
167 | unsigned long size = huge_page_size(hstate); | |
6d0fd598 HD |
168 | /* The only possible mapping was handled on last iteration */ |
169 | if (pvmw->pte) | |
170 | return not_found(pvmw); | |
9c67a207 PX |
171 | /* |
172 | * All callers that get here will already hold the | |
173 | * i_mmap_rwsem. Therefore, no additional locks need to be | |
174 | * taken before calling hugetlb_walk(). | |
175 | */ | |
176 | pvmw->pte = hugetlb_walk(vma, pvmw->address, size); | |
ace71a19 KS |
177 | if (!pvmw->pte) |
178 | return false; | |
179 | ||
8f0b747d | 180 | pvmw->ptl = huge_pte_lock(hstate, mm, pvmw->pte); |
ace71a19 KS |
181 | if (!check_pte(pvmw)) |
182 | return not_found(pvmw); | |
183 | return true; | |
184 | } | |
6d0fd598 | 185 | |
2aff7a47 | 186 | end = vma_address_end(pvmw); |
6d0fd598 HD |
187 | if (pvmw->pte) |
188 | goto next_pte; | |
ace71a19 | 189 | restart: |
a9a7504d | 190 | do { |
b3807a91 | 191 | pgd = pgd_offset(mm, pvmw->address); |
a9a7504d HD |
192 | if (!pgd_present(*pgd)) { |
193 | step_forward(pvmw, PGDIR_SIZE); | |
194 | continue; | |
195 | } | |
b3807a91 | 196 | p4d = p4d_offset(pgd, pvmw->address); |
a9a7504d HD |
197 | if (!p4d_present(*p4d)) { |
198 | step_forward(pvmw, P4D_SIZE); | |
199 | continue; | |
200 | } | |
b3807a91 | 201 | pud = pud_offset(p4d, pvmw->address); |
a9a7504d HD |
202 | if (!pud_present(*pud)) { |
203 | step_forward(pvmw, PUD_SIZE); | |
204 | continue; | |
205 | } | |
e2e1d407 | 206 | |
b3807a91 | 207 | pvmw->pmd = pmd_offset(pud, pvmw->address); |
732ed558 | 208 | /* |
b3807a91 HD |
209 | * Make sure the pmd value isn't cached in a register by the |
210 | * compiler and used as a stale value after we've observed a | |
211 | * subsequent update. | |
732ed558 | 212 | */ |
b3807a91 HD |
213 | pmde = READ_ONCE(*pvmw->pmd); |
214 | ||
6472f6d2 MS |
215 | if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde) || |
216 | (pmd_present(pmde) && pmd_devmap(pmde))) { | |
b3807a91 HD |
217 | pvmw->ptl = pmd_lock(mm, pvmw->pmd); |
218 | pmde = *pvmw->pmd; | |
b3807a91 HD |
219 | if (!pmd_present(pmde)) { |
220 | swp_entry_t entry; | |
221 | ||
222 | if (!thp_migration_supported() || | |
223 | !(pvmw->flags & PVMW_MIGRATION)) | |
224 | return not_found(pvmw); | |
225 | entry = pmd_to_swp_entry(pmde); | |
226 | if (!is_migration_entry(entry) || | |
0d206b5d | 227 | !check_pmd(swp_offset_pfn(entry), pvmw)) |
b3807a91 HD |
228 | return not_found(pvmw); |
229 | return true; | |
230 | } | |
6472f6d2 MS |
231 | if (likely(pmd_trans_huge(pmde) || pmd_devmap(pmde))) { |
232 | if (pvmw->flags & PVMW_MIGRATION) | |
233 | return not_found(pvmw); | |
234 | if (!check_pmd(pmd_pfn(pmde), pvmw)) | |
235 | return not_found(pvmw); | |
236 | return true; | |
237 | } | |
b3807a91 HD |
238 | /* THP pmd was split under us: handle on pte level */ |
239 | spin_unlock(pvmw->ptl); | |
240 | pvmw->ptl = NULL; | |
241 | } else if (!pmd_present(pmde)) { | |
242 | /* | |
243 | * If PVMW_SYNC, take and drop THP pmd lock so that we | |
244 | * cannot return prematurely, while zap_huge_pmd() has | |
245 | * cleared *pmd but not decremented compound_mapcount(). | |
246 | */ | |
247 | if ((pvmw->flags & PVMW_SYNC) && | |
c453d8c7 | 248 | transhuge_vma_suitable(vma, pvmw->address) && |
2aff7a47 | 249 | (pvmw->nr_pages >= HPAGE_PMD_NR)) { |
b3807a91 | 250 | spinlock_t *ptl = pmd_lock(mm, pvmw->pmd); |
732ed558 | 251 | |
b3807a91 HD |
252 | spin_unlock(ptl); |
253 | } | |
a9a7504d HD |
254 | step_forward(pvmw, PMD_SIZE); |
255 | continue; | |
732ed558 | 256 | } |
b3807a91 HD |
257 | if (!map_pte(pvmw)) |
258 | goto next_pte; | |
47446630 | 259 | this_pte: |
ace71a19 KS |
260 | if (check_pte(pvmw)) |
261 | return true; | |
d75450ff | 262 | next_pte: |
d75450ff | 263 | do { |
ace71a19 | 264 | pvmw->address += PAGE_SIZE; |
494334e4 | 265 | if (pvmw->address >= end) |
ace71a19 KS |
266 | return not_found(pvmw); |
267 | /* Did we cross page table boundary? */ | |
44828248 | 268 | if ((pvmw->address & (PMD_SIZE - PAGE_SIZE)) == 0) { |
ace71a19 KS |
269 | if (pvmw->ptl) { |
270 | spin_unlock(pvmw->ptl); | |
271 | pvmw->ptl = NULL; | |
272 | } | |
44828248 HD |
273 | pte_unmap(pvmw->pte); |
274 | pvmw->pte = NULL; | |
ace71a19 | 275 | goto restart; |
ace71a19 | 276 | } |
44828248 | 277 | pvmw->pte++; |
a7a69d8b HD |
278 | if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) { |
279 | pvmw->ptl = pte_lockptr(mm, pvmw->pmd); | |
280 | spin_lock(pvmw->ptl); | |
281 | } | |
ace71a19 KS |
282 | } while (pte_none(*pvmw->pte)); |
283 | ||
284 | if (!pvmw->ptl) { | |
285 | pvmw->ptl = pte_lockptr(mm, pvmw->pmd); | |
286 | spin_lock(pvmw->ptl); | |
287 | } | |
47446630 | 288 | goto this_pte; |
a9a7504d HD |
289 | } while (pvmw->address < end); |
290 | ||
291 | return false; | |
ace71a19 | 292 | } |
6a328a62 KS |
293 | |
294 | /** | |
295 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
296 | * @page: the page to test | |
297 | * @vma: the VMA to test | |
298 | * | |
299 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
300 | * if the page is not mapped into the page tables of this VMA. Only | |
301 | * valid for normal file or anonymous VMAs. | |
302 | */ | |
303 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) | |
304 | { | |
305 | struct page_vma_mapped_walk pvmw = { | |
2aff7a47 MWO |
306 | .pfn = page_to_pfn(page), |
307 | .nr_pages = 1, | |
6a328a62 KS |
308 | .vma = vma, |
309 | .flags = PVMW_SYNC, | |
310 | }; | |
6a328a62 | 311 | |
494334e4 HD |
312 | pvmw.address = vma_address(page, vma); |
313 | if (pvmw.address == -EFAULT) | |
6a328a62 | 314 | return 0; |
6a328a62 KS |
315 | if (!page_vma_mapped_walk(&pvmw)) |
316 | return 0; | |
317 | page_vma_mapped_walk_done(&pvmw); | |
318 | return 1; | |
319 | } |