]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * linux/mm/mincore.c | |
3 | * | |
4 | * Copyright (C) 1994-2006 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * The mincore() system call. | |
9 | */ | |
10 | #include <linux/pagemap.h> | |
11 | #include <linux/gfp.h> | |
12 | #include <linux/mm.h> | |
13 | #include <linux/mman.h> | |
14 | #include <linux/syscalls.h> | |
15 | #include <linux/swap.h> | |
16 | #include <linux/swapops.h> | |
17 | #include <linux/hugetlb.h> | |
18 | ||
19 | #include <linux/uaccess.h> | |
20 | #include <asm/pgtable.h> | |
21 | ||
22 | static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr, | |
23 | unsigned long end, struct mm_walk *walk) | |
24 | { | |
25 | #ifdef CONFIG_HUGETLB_PAGE | |
26 | unsigned char present; | |
27 | unsigned char *vec = walk->private; | |
28 | ||
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; | |
37 | #else | |
38 | BUG(); | |
39 | #endif | |
40 | return 0; | |
41 | } | |
42 | ||
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 | */ | |
49 | static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) | |
50 | { | |
51 | unsigned char present = 0; | |
52 | struct page *page; | |
53 | ||
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 | |
58 | * tmpfs's .fault). So swapped out tmpfs mappings are tested here. | |
59 | */ | |
60 | #ifdef CONFIG_SWAP | |
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), | |
70 | swp_offset(swp)); | |
71 | } | |
72 | } else | |
73 | page = find_get_page(mapping, pgoff); | |
74 | #else | |
75 | page = find_get_page(mapping, pgoff); | |
76 | #endif | |
77 | if (page) { | |
78 | present = PageUptodate(page); | |
79 | put_page(page); | |
80 | } | |
81 | ||
82 | return present; | |
83 | } | |
84 | ||
85 | static int __mincore_unmapped_range(unsigned long addr, unsigned long end, | |
86 | struct vm_area_struct *vma, unsigned char *vec) | |
87 | { | |
88 | unsigned long nr = (end - addr) >> PAGE_SHIFT; | |
89 | int i; | |
90 | ||
91 | if (vma->vm_file) { | |
92 | pgoff_t pgoff; | |
93 | ||
94 | pgoff = linear_page_index(vma, addr); | |
95 | for (i = 0; i < nr; i++, pgoff++) | |
96 | vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); | |
97 | } else { | |
98 | for (i = 0; i < nr; i++) | |
99 | vec[i] = 0; | |
100 | } | |
101 | return nr; | |
102 | } | |
103 | ||
104 | static int mincore_unmapped_range(unsigned long addr, unsigned long end, | |
105 | struct mm_walk *walk) | |
106 | { | |
107 | walk->private += __mincore_unmapped_range(addr, end, | |
108 | walk->vma, walk->private); | |
109 | return 0; | |
110 | } | |
111 | ||
112 | static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, | |
113 | struct mm_walk *walk) | |
114 | { | |
115 | spinlock_t *ptl; | |
116 | struct vm_area_struct *vma = walk->vma; | |
117 | pte_t *ptep; | |
118 | unsigned char *vec = walk->private; | |
119 | int nr = (end - addr) >> PAGE_SHIFT; | |
120 | ||
121 | ptl = pmd_trans_huge_lock(pmd, vma); | |
122 | if (ptl) { | |
123 | memset(vec, 1, nr); | |
124 | spin_unlock(ptl); | |
125 | goto out; | |
126 | } | |
127 | ||
128 | if (pmd_trans_unstable(pmd)) { | |
129 | __mincore_unmapped_range(addr, end, vma, vec); | |
130 | goto out; | |
131 | } | |
132 | ||
133 | ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); | |
134 | for (; addr != end; ptep++, addr += PAGE_SIZE) { | |
135 | pte_t pte = *ptep; | |
136 | ||
137 | if (pte_none(pte)) | |
138 | __mincore_unmapped_range(addr, addr + PAGE_SIZE, | |
139 | vma, vec); | |
140 | else if (pte_present(pte)) | |
141 | *vec = 1; | |
142 | else { /* pte is a swap entry */ | |
143 | swp_entry_t entry = pte_to_swp_entry(pte); | |
144 | ||
145 | if (non_swap_entry(entry)) { | |
146 | /* | |
147 | * migration or hwpoison entries are always | |
148 | * uptodate | |
149 | */ | |
150 | *vec = 1; | |
151 | } else { | |
152 | #ifdef CONFIG_SWAP | |
153 | *vec = mincore_page(swap_address_space(entry), | |
154 | swp_offset(entry)); | |
155 | #else | |
156 | WARN_ON(1); | |
157 | *vec = 1; | |
158 | #endif | |
159 | } | |
160 | } | |
161 | vec++; | |
162 | } | |
163 | pte_unmap_unlock(ptep - 1, ptl); | |
164 | out: | |
165 | walk->private += nr; | |
166 | cond_resched(); | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* | |
171 | * Do a chunk of "sys_mincore()". We've already checked | |
172 | * all the arguments, we hold the mmap semaphore: we should | |
173 | * just return the amount of info we're asked for. | |
174 | */ | |
175 | static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec) | |
176 | { | |
177 | struct vm_area_struct *vma; | |
178 | unsigned long end; | |
179 | int err; | |
180 | struct mm_walk mincore_walk = { | |
181 | .pmd_entry = mincore_pte_range, | |
182 | .pte_hole = mincore_unmapped_range, | |
183 | .hugetlb_entry = mincore_hugetlb, | |
184 | .private = vec, | |
185 | }; | |
186 | ||
187 | vma = find_vma(current->mm, addr); | |
188 | if (!vma || addr < vma->vm_start) | |
189 | return -ENOMEM; | |
190 | mincore_walk.mm = vma->vm_mm; | |
191 | end = min(vma->vm_end, addr + (pages << PAGE_SHIFT)); | |
192 | err = walk_page_range(addr, end, &mincore_walk); | |
193 | if (err < 0) | |
194 | return err; | |
195 | return (end - addr) >> PAGE_SHIFT; | |
196 | } | |
197 | ||
198 | /* | |
199 | * The mincore(2) system call. | |
200 | * | |
201 | * mincore() returns the memory residency status of the pages in the | |
202 | * current process's address space specified by [addr, addr + len). | |
203 | * The status is returned in a vector of bytes. The least significant | |
204 | * bit of each byte is 1 if the referenced page is in memory, otherwise | |
205 | * it is zero. | |
206 | * | |
207 | * Because the status of a page can change after mincore() checks it | |
208 | * but before it returns to the application, the returned vector may | |
209 | * contain stale information. Only locked pages are guaranteed to | |
210 | * remain in memory. | |
211 | * | |
212 | * return values: | |
213 | * zero - success | |
214 | * -EFAULT - vec points to an illegal address | |
215 | * -EINVAL - addr is not a multiple of PAGE_SIZE | |
216 | * -ENOMEM - Addresses in the range [addr, addr + len] are | |
217 | * invalid for the address space of this process, or | |
218 | * specify one or more pages which are not currently | |
219 | * mapped | |
220 | * -EAGAIN - A kernel resource was temporarily unavailable. | |
221 | */ | |
222 | SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len, | |
223 | unsigned char __user *, vec) | |
224 | { | |
225 | long retval; | |
226 | unsigned long pages; | |
227 | unsigned char *tmp; | |
228 | ||
229 | /* Check the start address: needs to be page-aligned.. */ | |
230 | if (start & ~PAGE_MASK) | |
231 | return -EINVAL; | |
232 | ||
233 | /* ..and we need to be passed a valid user-space range */ | |
234 | if (!access_ok(VERIFY_READ, (void __user *) start, len)) | |
235 | return -ENOMEM; | |
236 | ||
237 | /* This also avoids any overflows on PAGE_ALIGN */ | |
238 | pages = len >> PAGE_SHIFT; | |
239 | pages += (offset_in_page(len)) != 0; | |
240 | ||
241 | if (!access_ok(VERIFY_WRITE, vec, pages)) | |
242 | return -EFAULT; | |
243 | ||
244 | tmp = (void *) __get_free_page(GFP_USER); | |
245 | if (!tmp) | |
246 | return -EAGAIN; | |
247 | ||
248 | retval = 0; | |
249 | while (pages) { | |
250 | /* | |
251 | * Do at most PAGE_SIZE entries per iteration, due to | |
252 | * the temporary buffer size. | |
253 | */ | |
254 | down_read(¤t->mm->mmap_sem); | |
255 | retval = do_mincore(start, min(pages, PAGE_SIZE), tmp); | |
256 | up_read(¤t->mm->mmap_sem); | |
257 | ||
258 | if (retval <= 0) | |
259 | break; | |
260 | if (copy_to_user(vec, tmp, retval)) { | |
261 | retval = -EFAULT; | |
262 | break; | |
263 | } | |
264 | pages -= retval; | |
265 | vec += retval; | |
266 | start += retval << PAGE_SHIFT; | |
267 | retval = 0; | |
268 | } | |
269 | free_page((unsigned long) tmp); | |
270 | return retval; | |
271 | } |