]>
git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - mm/mincore.c
1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1994-2006 Linus Torvalds
9 * The mincore() system call.
11 #include <linux/pagemap.h>
12 #include <linux/gfp.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>
21 #include <linux/uaccess.h>
22 #include <asm/pgtable.h>
24 static int mincore_hugetlb(pte_t
*pte
, unsigned long hmask
, unsigned long addr
,
25 unsigned long end
, struct mm_walk
*walk
)
27 #ifdef CONFIG_HUGETLB_PAGE
28 unsigned char present
;
29 unsigned char *vec
= walk
->private;
32 * Hugepages under user process are always in RAM and never
33 * swapped out, but theoretically it needs to be checked.
35 present
= pte
&& !huge_pte_none(huge_ptep_get(pte
));
36 for (; addr
!= end
; vec
++, addr
+= PAGE_SIZE
)
46 * Later we can get more picky about what "in core" means precisely.
47 * For now, simply check to see if the page is in the page cache,
48 * and is up to date; i.e. that no page-in operation would be required
49 * at this time if an application were to map and access this page.
51 static unsigned char mincore_page(struct address_space
*mapping
, pgoff_t pgoff
)
53 unsigned char present
= 0;
57 * When tmpfs swaps out a page from a file, any process mapping that
58 * file will not get a swp_entry_t in its pte, but rather it is like
59 * any other file mapping (ie. marked !present and faulted in with
60 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
63 if (shmem_mapping(mapping
)) {
64 page
= find_get_entry(mapping
, pgoff
);
66 * shmem/tmpfs may return swap: account for swapcache
69 if (xa_is_value(page
)) {
70 swp_entry_t swp
= radix_to_swp_entry(page
);
71 page
= find_get_page(swap_address_space(swp
),
75 page
= find_get_page(mapping
, pgoff
);
77 page
= find_get_page(mapping
, pgoff
);
80 present
= PageUptodate(page
);
87 static int __mincore_unmapped_range(unsigned long addr
, unsigned long end
,
88 struct vm_area_struct
*vma
, unsigned char *vec
)
90 unsigned long nr
= (end
- addr
) >> PAGE_SHIFT
;
96 pgoff
= linear_page_index(vma
, addr
);
97 for (i
= 0; i
< nr
; i
++, pgoff
++)
98 vec
[i
] = mincore_page(vma
->vm_file
->f_mapping
, pgoff
);
100 for (i
= 0; i
< nr
; i
++)
106 static int mincore_unmapped_range(unsigned long addr
, unsigned long end
,
107 struct mm_walk
*walk
)
109 walk
->private += __mincore_unmapped_range(addr
, end
,
110 walk
->vma
, walk
->private);
114 static int mincore_pte_range(pmd_t
*pmd
, unsigned long addr
, unsigned long end
,
115 struct mm_walk
*walk
)
118 struct vm_area_struct
*vma
= walk
->vma
;
120 unsigned char *vec
= walk
->private;
121 int nr
= (end
- addr
) >> PAGE_SHIFT
;
123 ptl
= pmd_trans_huge_lock(pmd
, vma
);
130 if (pmd_trans_unstable(pmd
)) {
131 __mincore_unmapped_range(addr
, end
, vma
, vec
);
135 ptep
= pte_offset_map_lock(walk
->mm
, pmd
, addr
, &ptl
);
136 for (; addr
!= end
; ptep
++, addr
+= PAGE_SIZE
) {
140 __mincore_unmapped_range(addr
, addr
+ PAGE_SIZE
,
142 else if (pte_present(pte
))
144 else { /* pte is a swap entry */
145 swp_entry_t entry
= pte_to_swp_entry(pte
);
147 if (non_swap_entry(entry
)) {
149 * migration or hwpoison entries are always
155 *vec
= mincore_page(swap_address_space(entry
),
165 pte_unmap_unlock(ptep
- 1, ptl
);
173 * Do a chunk of "sys_mincore()". We've already checked
174 * all the arguments, we hold the mmap semaphore: we should
175 * just return the amount of info we're asked for.
177 static long do_mincore(unsigned long addr
, unsigned long pages
, unsigned char *vec
)
179 struct vm_area_struct
*vma
;
182 struct mm_walk mincore_walk
= {
183 .pmd_entry
= mincore_pte_range
,
184 .pte_hole
= mincore_unmapped_range
,
185 .hugetlb_entry
= mincore_hugetlb
,
189 vma
= find_vma(current
->mm
, addr
);
190 if (!vma
|| addr
< vma
->vm_start
)
192 mincore_walk
.mm
= vma
->vm_mm
;
193 end
= min(vma
->vm_end
, addr
+ (pages
<< PAGE_SHIFT
));
194 err
= walk_page_range(addr
, end
, &mincore_walk
);
197 return (end
- addr
) >> PAGE_SHIFT
;
201 * The mincore(2) system call.
203 * mincore() returns the memory residency status of the pages in the
204 * current process's address space specified by [addr, addr + len).
205 * The status is returned in a vector of bytes. The least significant
206 * bit of each byte is 1 if the referenced page is in memory, otherwise
209 * Because the status of a page can change after mincore() checks it
210 * but before it returns to the application, the returned vector may
211 * contain stale information. Only locked pages are guaranteed to
216 * -EFAULT - vec points to an illegal address
217 * -EINVAL - addr is not a multiple of PAGE_SIZE
218 * -ENOMEM - Addresses in the range [addr, addr + len] are
219 * invalid for the address space of this process, or
220 * specify one or more pages which are not currently
222 * -EAGAIN - A kernel resource was temporarily unavailable.
224 SYSCALL_DEFINE3(mincore
, unsigned long, start
, size_t, len
,
225 unsigned char __user
*, vec
)
231 /* Check the start address: needs to be page-aligned.. */
232 if (start
& ~PAGE_MASK
)
235 /* ..and we need to be passed a valid user-space range */
236 if (!access_ok((void __user
*) start
, len
))
239 /* This also avoids any overflows on PAGE_ALIGN */
240 pages
= len
>> PAGE_SHIFT
;
241 pages
+= (offset_in_page(len
)) != 0;
243 if (!access_ok(vec
, pages
))
246 tmp
= (void *) __get_free_page(GFP_USER
);
253 * Do at most PAGE_SIZE entries per iteration, due to
254 * the temporary buffer size.
256 down_read(¤t
->mm
->mmap_sem
);
257 retval
= do_mincore(start
, min(pages
, PAGE_SIZE
), tmp
);
258 up_read(¤t
->mm
->mmap_sem
);
262 if (copy_to_user(vec
, tmp
, retval
)) {
268 start
+= retval
<< PAGE_SHIFT
;
271 free_page((unsigned long) tmp
);