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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 <asm/uaccess.h>
20#include <asm/pgtable.h>
21
22static 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 */
49static 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), swp.val);
70 }
71 } else
72 page = find_get_page(mapping, pgoff);
73#else
74 page = find_get_page(mapping, pgoff);
75#endif
76 if (page) {
77 present = PageUptodate(page);
78 put_page(page);
79 }
80
81 return present;
82}
83
84static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
85 struct vm_area_struct *vma, unsigned char *vec)
86{
87 unsigned long nr = (end - addr) >> PAGE_SHIFT;
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 }
100 return nr;
101}
102
103static 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;
109}
110
111static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
112 struct mm_walk *walk)
113{
114 spinlock_t *ptl;
115 struct vm_area_struct *vma = walk->vma;
116 pte_t *ptep;
117 unsigned char *vec = walk->private;
118 int nr = (end - addr) >> PAGE_SHIFT;
119
120 ptl = pmd_trans_huge_lock(pmd, vma);
121 if (ptl) {
122 memset(vec, 1, nr);
123 spin_unlock(ptl);
124 goto out;
125 }
126
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) {
134 pte_t pte = *ptep;
135
136 if (pte_none(pte))
137 __mincore_unmapped_range(addr, addr + PAGE_SIZE,
138 vma, vec);
139 else if (pte_present(pte))
140 *vec = 1;
141 else { /* pte is a swap entry */
142 swp_entry_t entry = pte_to_swp_entry(pte);
143
144 if (non_swap_entry(entry)) {
145 /*
146 * migration or hwpoison entries are always
147 * uptodate
148 */
149 *vec = 1;
150 } else {
151#ifdef CONFIG_SWAP
152 *vec = mincore_page(swap_address_space(entry),
153 entry.val);
154#else
155 WARN_ON(1);
156 *vec = 1;
157#endif
158 }
159 }
160 vec++;
161 }
162 pte_unmap_unlock(ptep - 1, ptl);
163out:
164 walk->private += nr;
165 cond_resched();
166 return 0;
167}
168
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 */
174static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
175{
176 struct vm_area_struct *vma;
177 unsigned long end;
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 };
185
186 vma = find_vma(current->mm, addr);
187 if (!vma || addr < vma->vm_start)
188 return -ENOMEM;
189 mincore_walk.mm = vma->vm_mm;
190 end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
191 err = walk_page_range(addr, end, &mincore_walk);
192 if (err < 0)
193 return err;
194 return (end - addr) >> PAGE_SHIFT;
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
214 * -EINVAL - addr is not a multiple of PAGE_SIZE
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 */
221SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
222 unsigned char __user *, vec)
223{
224 long retval;
225 unsigned long pages;
226 unsigned char *tmp;
227
228 /* Check the start address: needs to be page-aligned.. */
229 if (start & ~PAGE_MASK)
230 return -EINVAL;
231
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;
235
236 /* This also avoids any overflows on PAGE_ALIGN */
237 pages = len >> PAGE_SHIFT;
238 pages += (offset_in_page(len)) != 0;
239
240 if (!access_ok(VERIFY_WRITE, vec, pages))
241 return -EFAULT;
242
243 tmp = (void *) __get_free_page(GFP_USER);
244 if (!tmp)
245 return -EAGAIN;
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);
254 retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
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;
262 }
263 pages -= retval;
264 vec += retval;
265 start += retval << PAGE_SHIFT;
266 retval = 0;
267 }
268 free_page((unsigned long) tmp);
269 return retval;
270}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mincore.c
4 *
5 * Copyright (C) 1994-2006 Linus Torvalds
6 */
7
8/*
9 * The mincore() system call.
10 */
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#include "swap.h"
24
25static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
26 unsigned long end, struct mm_walk *walk)
27{
28#ifdef CONFIG_HUGETLB_PAGE
29 unsigned char present;
30 unsigned char *vec = walk->private;
31
32 /*
33 * Hugepages under user process are always in RAM and never
34 * swapped out, but theoretically it needs to be checked.
35 */
36 present = pte && !huge_pte_none_mostly(huge_ptep_get(walk->mm, addr, pte));
37 for (; addr != end; vec++, addr += PAGE_SIZE)
38 *vec = present;
39 walk->private = vec;
40#else
41 BUG();
42#endif
43 return 0;
44}
45
46/*
47 * Later we can get more picky about what "in core" means precisely.
48 * For now, simply check to see if the page is in the page cache,
49 * and is up to date; i.e. that no page-in operation would be required
50 * at this time if an application were to map and access this page.
51 */
52static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
53{
54 unsigned char present = 0;
55 struct folio *folio;
56
57 /*
58 * When tmpfs swaps out a page from a file, any process mapping that
59 * file will not get a swp_entry_t in its pte, but rather it is like
60 * any other file mapping (ie. marked !present and faulted in with
61 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
62 */
63 folio = filemap_get_incore_folio(mapping, index);
64 if (!IS_ERR(folio)) {
65 present = folio_test_uptodate(folio);
66 folio_put(folio);
67 }
68
69 return present;
70}
71
72static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
73 struct vm_area_struct *vma, unsigned char *vec)
74{
75 unsigned long nr = (end - addr) >> PAGE_SHIFT;
76 int i;
77
78 if (vma->vm_file) {
79 pgoff_t pgoff;
80
81 pgoff = linear_page_index(vma, addr);
82 for (i = 0; i < nr; i++, pgoff++)
83 vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
84 } else {
85 for (i = 0; i < nr; i++)
86 vec[i] = 0;
87 }
88 return nr;
89}
90
91static int mincore_unmapped_range(unsigned long addr, unsigned long end,
92 __always_unused int depth,
93 struct mm_walk *walk)
94{
95 walk->private += __mincore_unmapped_range(addr, end,
96 walk->vma, walk->private);
97 return 0;
98}
99
100static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
101 struct mm_walk *walk)
102{
103 spinlock_t *ptl;
104 struct vm_area_struct *vma = walk->vma;
105 pte_t *ptep;
106 unsigned char *vec = walk->private;
107 int nr = (end - addr) >> PAGE_SHIFT;
108
109 ptl = pmd_trans_huge_lock(pmd, vma);
110 if (ptl) {
111 memset(vec, 1, nr);
112 spin_unlock(ptl);
113 goto out;
114 }
115
116 ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
117 if (!ptep) {
118 walk->action = ACTION_AGAIN;
119 return 0;
120 }
121 for (; addr != end; ptep++, addr += PAGE_SIZE) {
122 pte_t pte = ptep_get(ptep);
123
124 /* We need to do cache lookup too for pte markers */
125 if (pte_none_mostly(pte))
126 __mincore_unmapped_range(addr, addr + PAGE_SIZE,
127 vma, vec);
128 else if (pte_present(pte))
129 *vec = 1;
130 else { /* pte is a swap entry */
131 swp_entry_t entry = pte_to_swp_entry(pte);
132
133 if (non_swap_entry(entry)) {
134 /*
135 * migration or hwpoison entries are always
136 * uptodate
137 */
138 *vec = 1;
139 } else {
140#ifdef CONFIG_SWAP
141 *vec = mincore_page(swap_address_space(entry),
142 swap_cache_index(entry));
143#else
144 WARN_ON(1);
145 *vec = 1;
146#endif
147 }
148 }
149 vec++;
150 }
151 pte_unmap_unlock(ptep - 1, ptl);
152out:
153 walk->private += nr;
154 cond_resched();
155 return 0;
156}
157
158static inline bool can_do_mincore(struct vm_area_struct *vma)
159{
160 if (vma_is_anonymous(vma))
161 return true;
162 if (!vma->vm_file)
163 return false;
164 /*
165 * Reveal pagecache information only for non-anonymous mappings that
166 * correspond to the files the calling process could (if tried) open
167 * for writing; otherwise we'd be including shared non-exclusive
168 * mappings, which opens a side channel.
169 */
170 return inode_owner_or_capable(&nop_mnt_idmap,
171 file_inode(vma->vm_file)) ||
172 file_permission(vma->vm_file, MAY_WRITE) == 0;
173}
174
175static const struct mm_walk_ops mincore_walk_ops = {
176 .pmd_entry = mincore_pte_range,
177 .pte_hole = mincore_unmapped_range,
178 .hugetlb_entry = mincore_hugetlb,
179 .walk_lock = PGWALK_RDLOCK,
180};
181
182/*
183 * Do a chunk of "sys_mincore()". We've already checked
184 * all the arguments, we hold the mmap semaphore: we should
185 * just return the amount of info we're asked for.
186 */
187static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
188{
189 struct vm_area_struct *vma;
190 unsigned long end;
191 int err;
192
193 vma = vma_lookup(current->mm, addr);
194 if (!vma)
195 return -ENOMEM;
196 end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
197 if (!can_do_mincore(vma)) {
198 unsigned long pages = DIV_ROUND_UP(end - addr, PAGE_SIZE);
199 memset(vec, 1, pages);
200 return pages;
201 }
202 err = walk_page_range(vma->vm_mm, addr, end, &mincore_walk_ops, vec);
203 if (err < 0)
204 return err;
205 return (end - addr) >> PAGE_SHIFT;
206}
207
208/*
209 * The mincore(2) system call.
210 *
211 * mincore() returns the memory residency status of the pages in the
212 * current process's address space specified by [addr, addr + len).
213 * The status is returned in a vector of bytes. The least significant
214 * bit of each byte is 1 if the referenced page is in memory, otherwise
215 * it is zero.
216 *
217 * Because the status of a page can change after mincore() checks it
218 * but before it returns to the application, the returned vector may
219 * contain stale information. Only locked pages are guaranteed to
220 * remain in memory.
221 *
222 * return values:
223 * zero - success
224 * -EFAULT - vec points to an illegal address
225 * -EINVAL - addr is not a multiple of PAGE_SIZE
226 * -ENOMEM - Addresses in the range [addr, addr + len] are
227 * invalid for the address space of this process, or
228 * specify one or more pages which are not currently
229 * mapped
230 * -EAGAIN - A kernel resource was temporarily unavailable.
231 */
232SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
233 unsigned char __user *, vec)
234{
235 long retval;
236 unsigned long pages;
237 unsigned char *tmp;
238
239 start = untagged_addr(start);
240
241 /* Check the start address: needs to be page-aligned.. */
242 if (start & ~PAGE_MASK)
243 return -EINVAL;
244
245 /* ..and we need to be passed a valid user-space range */
246 if (!access_ok((void __user *) start, len))
247 return -ENOMEM;
248
249 /* This also avoids any overflows on PAGE_ALIGN */
250 pages = len >> PAGE_SHIFT;
251 pages += (offset_in_page(len)) != 0;
252
253 if (!access_ok(vec, pages))
254 return -EFAULT;
255
256 tmp = (void *) __get_free_page(GFP_USER);
257 if (!tmp)
258 return -EAGAIN;
259
260 retval = 0;
261 while (pages) {
262 /*
263 * Do at most PAGE_SIZE entries per iteration, due to
264 * the temporary buffer size.
265 */
266 mmap_read_lock(current->mm);
267 retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
268 mmap_read_unlock(current->mm);
269
270 if (retval <= 0)
271 break;
272 if (copy_to_user(vec, tmp, retval)) {
273 retval = -EFAULT;
274 break;
275 }
276 pages -= retval;
277 vec += retval;
278 start += retval << PAGE_SHIFT;
279 retval = 0;
280 }
281 free_page((unsigned long) tmp);
282 return retval;
283}