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11#include <linux/pagemap.h>
12#include <linux/gfp.h>
13#include <linux/pagewalk.h>
14#include <linux/mman.h>
15#include <linux/syscalls.h>
16#include <linux/swap.h>
17#include <linux/swapops.h>
18#include <linux/shmem_fs.h>
19#include <linux/hugetlb.h>
20#include <linux/pgtable.h>
21
22#include <linux/uaccess.h>
23
24static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
25 unsigned long end, struct mm_walk *walk)
26{
27#ifdef CONFIG_HUGETLB_PAGE
28 unsigned char present;
29 unsigned char *vec = walk->private;
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34
35 present = pte && !huge_pte_none(huge_ptep_get(pte));
36 for (; addr != end; vec++, addr += PAGE_SIZE)
37 *vec = present;
38 walk->private = vec;
39#else
40 BUG();
41#endif
42 return 0;
43}
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50
51static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
52{
53 unsigned char present = 0;
54 struct page *page;
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62 page = find_get_incore_page(mapping, index);
63 if (page) {
64 present = PageUptodate(page);
65 put_page(page);
66 }
67
68 return present;
69}
70
71static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
72 struct vm_area_struct *vma, unsigned char *vec)
73{
74 unsigned long nr = (end - addr) >> PAGE_SHIFT;
75 int i;
76
77 if (vma->vm_file) {
78 pgoff_t pgoff;
79
80 pgoff = linear_page_index(vma, addr);
81 for (i = 0; i < nr; i++, pgoff++)
82 vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
83 } else {
84 for (i = 0; i < nr; i++)
85 vec[i] = 0;
86 }
87 return nr;
88}
89
90static int mincore_unmapped_range(unsigned long addr, unsigned long end,
91 __always_unused int depth,
92 struct mm_walk *walk)
93{
94 walk->private += __mincore_unmapped_range(addr, end,
95 walk->vma, walk->private);
96 return 0;
97}
98
99static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
100 struct mm_walk *walk)
101{
102 spinlock_t *ptl;
103 struct vm_area_struct *vma = walk->vma;
104 pte_t *ptep;
105 unsigned char *vec = walk->private;
106 int nr = (end - addr) >> PAGE_SHIFT;
107
108 ptl = pmd_trans_huge_lock(pmd, vma);
109 if (ptl) {
110 memset(vec, 1, nr);
111 spin_unlock(ptl);
112 goto out;
113 }
114
115 if (pmd_trans_unstable(pmd)) {
116 __mincore_unmapped_range(addr, end, vma, vec);
117 goto out;
118 }
119
120 ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
121 for (; addr != end; ptep++, addr += PAGE_SIZE) {
122 pte_t pte = *ptep;
123
124 if (pte_none(pte))
125 __mincore_unmapped_range(addr, addr + PAGE_SIZE,
126 vma, vec);
127 else if (pte_present(pte))
128 *vec = 1;
129 else {
130 swp_entry_t entry = pte_to_swp_entry(pte);
131
132 if (non_swap_entry(entry)) {
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136
137 *vec = 1;
138 } else {
139#ifdef CONFIG_SWAP
140 *vec = mincore_page(swap_address_space(entry),
141 swp_offset(entry));
142#else
143 WARN_ON(1);
144 *vec = 1;
145#endif
146 }
147 }
148 vec++;
149 }
150 pte_unmap_unlock(ptep - 1, ptl);
151out:
152 walk->private += nr;
153 cond_resched();
154 return 0;
155}
156
157static inline bool can_do_mincore(struct vm_area_struct *vma)
158{
159 if (vma_is_anonymous(vma))
160 return true;
161 if (!vma->vm_file)
162 return false;
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169 return inode_owner_or_capable(file_inode(vma->vm_file)) ||
170 inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
171}
172
173static const struct mm_walk_ops mincore_walk_ops = {
174 .pmd_entry = mincore_pte_range,
175 .pte_hole = mincore_unmapped_range,
176 .hugetlb_entry = mincore_hugetlb,
177};
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183
184static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
185{
186 struct vm_area_struct *vma;
187 unsigned long end;
188 int err;
189
190 vma = find_vma(current->mm, addr);
191 if (!vma || addr < vma->vm_start)
192 return -ENOMEM;
193 end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
194 if (!can_do_mincore(vma)) {
195 unsigned long pages = DIV_ROUND_UP(end - addr, PAGE_SIZE);
196 memset(vec, 1, pages);
197 return pages;
198 }
199 err = walk_page_range(vma->vm_mm, addr, end, &mincore_walk_ops, vec);
200 if (err < 0)
201 return err;
202 return (end - addr) >> PAGE_SHIFT;
203}
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229SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
230 unsigned char __user *, vec)
231{
232 long retval;
233 unsigned long pages;
234 unsigned char *tmp;
235
236 start = untagged_addr(start);
237
238
239 if (start & ~PAGE_MASK)
240 return -EINVAL;
241
242
243 if (!access_ok((void __user *) start, len))
244 return -ENOMEM;
245
246
247 pages = len >> PAGE_SHIFT;
248 pages += (offset_in_page(len)) != 0;
249
250 if (!access_ok(vec, pages))
251 return -EFAULT;
252
253 tmp = (void *) __get_free_page(GFP_USER);
254 if (!tmp)
255 return -EAGAIN;
256
257 retval = 0;
258 while (pages) {
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263 mmap_read_lock(current->mm);
264 retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
265 mmap_read_unlock(current->mm);
266
267 if (retval <= 0)
268 break;
269 if (copy_to_user(vec, tmp, retval)) {
270 retval = -EFAULT;
271 break;
272 }
273 pages -= retval;
274 vec += retval;
275 start += retval << PAGE_SHIFT;
276 retval = 0;
277 }
278 free_page((unsigned long) tmp);
279 return retval;
280}
281