Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/mincore.c | |
3 | * | |
2f77d107 | 4 | * Copyright (C) 1994-2006 Linus Torvalds |
1da177e4 LT |
5 | */ |
6 | ||
7 | /* | |
8 | * The mincore() system call. | |
9 | */ | |
1da177e4 | 10 | #include <linux/pagemap.h> |
5a0e3ad6 | 11 | #include <linux/gfp.h> |
1da177e4 LT |
12 | #include <linux/mm.h> |
13 | #include <linux/mman.h> | |
14 | #include <linux/syscalls.h> | |
42da9cbd NP |
15 | #include <linux/swap.h> |
16 | #include <linux/swapops.h> | |
4f16fc10 | 17 | #include <linux/hugetlb.h> |
1da177e4 LT |
18 | |
19 | #include <asm/uaccess.h> | |
20 | #include <asm/pgtable.h> | |
21 | ||
1e25a271 NH |
22 | static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr, |
23 | unsigned long end, struct mm_walk *walk) | |
f4884010 JW |
24 | { |
25 | #ifdef CONFIG_HUGETLB_PAGE | |
1e25a271 NH |
26 | unsigned char present; |
27 | unsigned char *vec = walk->private; | |
f4884010 | 28 | |
1e25a271 NH |
29 | /* |
30 | * Hugepages under user process are always in RAM and never | |
31 | * swapped out, but theoretically it needs to be checked. | |
32 | */ | |
33 | present = pte && !huge_pte_none(huge_ptep_get(pte)); | |
34 | for (; addr != end; vec++, addr += PAGE_SIZE) | |
35 | *vec = present; | |
36 | walk->private = vec; | |
f4884010 JW |
37 | #else |
38 | BUG(); | |
39 | #endif | |
1e25a271 | 40 | return 0; |
f4884010 JW |
41 | } |
42 | ||
1da177e4 LT |
43 | /* |
44 | * Later we can get more picky about what "in core" means precisely. | |
45 | * For now, simply check to see if the page is in the page cache, | |
46 | * and is up to date; i.e. that no page-in operation would be required | |
47 | * at this time if an application were to map and access this page. | |
48 | */ | |
42da9cbd | 49 | static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) |
1da177e4 LT |
50 | { |
51 | unsigned char present = 0; | |
42da9cbd | 52 | struct page *page; |
1da177e4 | 53 | |
42da9cbd NP |
54 | /* |
55 | * When tmpfs swaps out a page from a file, any process mapping that | |
56 | * file will not get a swp_entry_t in its pte, but rather it is like | |
57 | * any other file mapping (ie. marked !present and faulted in with | |
3c18ddd1 | 58 | * tmpfs's .fault). So swapped out tmpfs mappings are tested here. |
42da9cbd | 59 | */ |
31475dd6 | 60 | #ifdef CONFIG_SWAP |
0cd6144a JW |
61 | if (shmem_mapping(mapping)) { |
62 | page = find_get_entry(mapping, pgoff); | |
63 | /* | |
64 | * shmem/tmpfs may return swap: account for swapcache | |
65 | * page too. | |
66 | */ | |
67 | if (radix_tree_exceptional_entry(page)) { | |
68 | swp_entry_t swp = radix_to_swp_entry(page); | |
69 | page = find_get_page(swap_address_space(swp), swp.val); | |
70 | } | |
71 | } else | |
72 | page = find_get_page(mapping, pgoff); | |
73 | #else | |
74 | page = find_get_page(mapping, pgoff); | |
31475dd6 | 75 | #endif |
1da177e4 LT |
76 | if (page) { |
77 | present = PageUptodate(page); | |
09cbfeaf | 78 | put_page(page); |
1da177e4 LT |
79 | } |
80 | ||
81 | return present; | |
82 | } | |
83 | ||
1e25a271 NH |
84 | static int __mincore_unmapped_range(unsigned long addr, unsigned long end, |
85 | struct vm_area_struct *vma, unsigned char *vec) | |
f4884010 | 86 | { |
25ef0e50 | 87 | unsigned long nr = (end - addr) >> PAGE_SHIFT; |
f4884010 JW |
88 | int i; |
89 | ||
90 | if (vma->vm_file) { | |
91 | pgoff_t pgoff; | |
92 | ||
93 | pgoff = linear_page_index(vma, addr); | |
94 | for (i = 0; i < nr; i++, pgoff++) | |
95 | vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); | |
96 | } else { | |
97 | for (i = 0; i < nr; i++) | |
98 | vec[i] = 0; | |
99 | } | |
1e25a271 NH |
100 | return nr; |
101 | } | |
102 | ||
103 | static int mincore_unmapped_range(unsigned long addr, unsigned long end, | |
104 | struct mm_walk *walk) | |
105 | { | |
106 | walk->private += __mincore_unmapped_range(addr, end, | |
107 | walk->vma, walk->private); | |
108 | return 0; | |
f4884010 JW |
109 | } |
110 | ||
1e25a271 NH |
111 | static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, |
112 | struct mm_walk *walk) | |
f4884010 JW |
113 | { |
114 | spinlock_t *ptl; | |
1e25a271 | 115 | struct vm_area_struct *vma = walk->vma; |
f4884010 | 116 | pte_t *ptep; |
1e25a271 NH |
117 | unsigned char *vec = walk->private; |
118 | int nr = (end - addr) >> PAGE_SHIFT; | |
119 | ||
b6ec57f4 KS |
120 | ptl = pmd_trans_huge_lock(pmd, vma); |
121 | if (ptl) { | |
1e25a271 NH |
122 | memset(vec, 1, nr); |
123 | spin_unlock(ptl); | |
124 | goto out; | |
125 | } | |
f4884010 | 126 | |
1e25a271 NH |
127 | if (pmd_trans_unstable(pmd)) { |
128 | __mincore_unmapped_range(addr, end, vma, vec); | |
129 | goto out; | |
130 | } | |
131 | ||
132 | ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); | |
133 | for (; addr != end; ptep++, addr += PAGE_SIZE) { | |
f4884010 | 134 | pte_t pte = *ptep; |
f4884010 JW |
135 | |
136 | if (pte_none(pte)) | |
1e25a271 NH |
137 | __mincore_unmapped_range(addr, addr + PAGE_SIZE, |
138 | vma, vec); | |
f4884010 | 139 | else if (pte_present(pte)) |
25ef0e50 | 140 | *vec = 1; |
0661a336 | 141 | else { /* pte is a swap entry */ |
f4884010 JW |
142 | swp_entry_t entry = pte_to_swp_entry(pte); |
143 | ||
c313dc5d WY |
144 | if (non_swap_entry(entry)) { |
145 | /* | |
146 | * migration or hwpoison entries are always | |
147 | * uptodate | |
148 | */ | |
25ef0e50 | 149 | *vec = 1; |
f4884010 JW |
150 | } else { |
151 | #ifdef CONFIG_SWAP | |
33806f06 | 152 | *vec = mincore_page(swap_address_space(entry), |
0661a336 | 153 | entry.val); |
f4884010 JW |
154 | #else |
155 | WARN_ON(1); | |
25ef0e50 | 156 | *vec = 1; |
f4884010 JW |
157 | #endif |
158 | } | |
159 | } | |
25ef0e50 | 160 | vec++; |
1e25a271 | 161 | } |
f4884010 | 162 | pte_unmap_unlock(ptep - 1, ptl); |
1e25a271 NH |
163 | out: |
164 | walk->private += nr; | |
165 | cond_resched(); | |
166 | return 0; | |
e48293fd JW |
167 | } |
168 | ||
2f77d107 LT |
169 | /* |
170 | * Do a chunk of "sys_mincore()". We've already checked | |
171 | * all the arguments, we hold the mmap semaphore: we should | |
172 | * just return the amount of info we're asked for. | |
173 | */ | |
6a60f1b3 | 174 | static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec) |
1da177e4 | 175 | { |
6a60f1b3 | 176 | struct vm_area_struct *vma; |
25ef0e50 | 177 | unsigned long end; |
1e25a271 NH |
178 | int err; |
179 | struct mm_walk mincore_walk = { | |
180 | .pmd_entry = mincore_pte_range, | |
181 | .pte_hole = mincore_unmapped_range, | |
182 | .hugetlb_entry = mincore_hugetlb, | |
183 | .private = vec, | |
184 | }; | |
1da177e4 | 185 | |
6a60f1b3 | 186 | vma = find_vma(current->mm, addr); |
4fb23e43 LT |
187 | if (!vma || addr < vma->vm_start) |
188 | return -ENOMEM; | |
1e25a271 | 189 | mincore_walk.mm = vma->vm_mm; |
25ef0e50 | 190 | end = min(vma->vm_end, addr + (pages << PAGE_SHIFT)); |
1e25a271 NH |
191 | err = walk_page_range(addr, end, &mincore_walk); |
192 | if (err < 0) | |
193 | return err; | |
25ef0e50 | 194 | return (end - addr) >> PAGE_SHIFT; |
1da177e4 LT |
195 | } |
196 | ||
197 | /* | |
198 | * The mincore(2) system call. | |
199 | * | |
200 | * mincore() returns the memory residency status of the pages in the | |
201 | * current process's address space specified by [addr, addr + len). | |
202 | * The status is returned in a vector of bytes. The least significant | |
203 | * bit of each byte is 1 if the referenced page is in memory, otherwise | |
204 | * it is zero. | |
205 | * | |
206 | * Because the status of a page can change after mincore() checks it | |
207 | * but before it returns to the application, the returned vector may | |
208 | * contain stale information. Only locked pages are guaranteed to | |
209 | * remain in memory. | |
210 | * | |
211 | * return values: | |
212 | * zero - success | |
213 | * -EFAULT - vec points to an illegal address | |
ea1754a0 | 214 | * -EINVAL - addr is not a multiple of PAGE_SIZE |
1da177e4 LT |
215 | * -ENOMEM - Addresses in the range [addr, addr + len] are |
216 | * invalid for the address space of this process, or | |
217 | * specify one or more pages which are not currently | |
218 | * mapped | |
219 | * -EAGAIN - A kernel resource was temporarily unavailable. | |
220 | */ | |
3480b257 HC |
221 | SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len, |
222 | unsigned char __user *, vec) | |
1da177e4 | 223 | { |
2f77d107 LT |
224 | long retval; |
225 | unsigned long pages; | |
226 | unsigned char *tmp; | |
1da177e4 | 227 | |
2f77d107 | 228 | /* Check the start address: needs to be page-aligned.. */ |
09cbfeaf | 229 | if (start & ~PAGE_MASK) |
2f77d107 | 230 | return -EINVAL; |
1da177e4 | 231 | |
2f77d107 LT |
232 | /* ..and we need to be passed a valid user-space range */ |
233 | if (!access_ok(VERIFY_READ, (void __user *) start, len)) | |
234 | return -ENOMEM; | |
1da177e4 | 235 | |
ea1754a0 | 236 | /* This also avoids any overflows on PAGE_ALIGN */ |
2f77d107 | 237 | pages = len >> PAGE_SHIFT; |
e7bbdd07 | 238 | pages += (offset_in_page(len)) != 0; |
1da177e4 | 239 | |
2f77d107 LT |
240 | if (!access_ok(VERIFY_WRITE, vec, pages)) |
241 | return -EFAULT; | |
1da177e4 | 242 | |
2f77d107 LT |
243 | tmp = (void *) __get_free_page(GFP_USER); |
244 | if (!tmp) | |
4fb23e43 | 245 | return -EAGAIN; |
2f77d107 LT |
246 | |
247 | retval = 0; | |
248 | while (pages) { | |
249 | /* | |
250 | * Do at most PAGE_SIZE entries per iteration, due to | |
251 | * the temporary buffer size. | |
252 | */ | |
253 | down_read(¤t->mm->mmap_sem); | |
6a60f1b3 | 254 | retval = do_mincore(start, min(pages, PAGE_SIZE), tmp); |
2f77d107 LT |
255 | up_read(¤t->mm->mmap_sem); |
256 | ||
257 | if (retval <= 0) | |
258 | break; | |
259 | if (copy_to_user(vec, tmp, retval)) { | |
260 | retval = -EFAULT; | |
261 | break; | |
1da177e4 | 262 | } |
2f77d107 LT |
263 | pages -= retval; |
264 | vec += retval; | |
265 | start += retval << PAGE_SHIFT; | |
266 | retval = 0; | |
1da177e4 | 267 | } |
2f77d107 LT |
268 | free_page((unsigned long) tmp); |
269 | return retval; | |
1da177e4 | 270 | } |