summaryrefslogblamecommitdiff
path: root/mm/pagewalk.c
blob: b4f27d22da916e44372111a88c1da5f1bc2b82f6 (plain) (tree) 
e6473092bd91 ^



































































































































1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131



































































































































                                                                              
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/sched.h>

static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
			  const struct mm_walk *walk, void *private)
{
	pte_t *pte;
	int err = 0;

	pte = pte_offset_map(pmd, addr);
	do {
		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private);
		if (err)
		       break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

	pte_unmap(pte);
	return err;
}

static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
			  const struct mm_walk *walk, void *private)
{
	pmd_t *pmd;
	unsigned long next;
	int err = 0;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd)) {
			if (walk->pte_hole)
				err = walk->pte_hole(addr, next, private);
			if (err)
				break;
			continue;
		}
		if (walk->pmd_entry)
			err = walk->pmd_entry(pmd, addr, next, private);
		if (!err && walk->pte_entry)
			err = walk_pte_range(pmd, addr, next, walk, private);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);

	return err;
}

static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
			  const struct mm_walk *walk, void *private)
{
	pud_t *pud;
	unsigned long next;
	int err = 0;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud)) {
			if (walk->pte_hole)
				err = walk->pte_hole(addr, next, private);
			if (err)
				break;
			continue;
		}
		if (walk->pud_entry)
			err = walk->pud_entry(pud, addr, next, private);
		if (!err && (walk->pmd_entry || walk->pte_entry))
			err = walk_pmd_range(pud, addr, next, walk, private);
		if (err)
			break;
	} while (pud++, addr = next, addr != end);

	return err;
}

/**
 * walk_page_range - walk a memory map's page tables with a callback
 * @mm - memory map to walk
 * @addr - starting address
 * @end - ending address
 * @walk - set of callbacks to invoke for each level of the tree
 * @private - private data passed to the callback function
 *
 * Recursively walk the page table for the memory area in a VMA,
 * calling supplied callbacks. Callbacks are called in-order (first
 * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
 * etc.). If lower-level callbacks are omitted, walking depth is reduced.
 *
 * Each callback receives an entry pointer, the start and end of the
 * associated range, and a caller-supplied private data pointer.
 *
 * No locks are taken, but the bottom level iterator will map PTE
 * directories from highmem if necessary.
 *
 * If any callback returns a non-zero value, the walk is aborted and
 * the return value is propagated back to the caller. Otherwise 0 is returned.
 */
int walk_page_range(const struct mm_struct *mm,
		    unsigned long addr, unsigned long end,
		    const struct mm_walk *walk, void *private)
{
	pgd_t *pgd;
	unsigned long next;
	int err = 0;

	if (addr >= end)
		return err;

	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd)) {
			if (walk->pte_hole)
				err = walk->pte_hole(addr, next, private);
			if (err)
				break;
			continue;
		}
		if (walk->pgd_entry)
			err = walk->pgd_entry(pgd, addr, next, private);
		if (!err &&
		    (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
			err = walk_pud_range(pgd, addr, next, walk, private);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);

	return err;
}