Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/pagewalk.h>
4#include <linux/ptdump.h>
5#include <linux/kasan.h>
6
7#ifdef CONFIG_KASAN
8/*
9 * This is an optimization for KASAN=y case. Since all kasan page tables
10 * eventually point to the kasan_early_shadow_page we could call note_page()
11 * right away without walking through lower level page tables. This saves
12 * us dozens of seconds (minutes for 5-level config) while checking for
13 * W+X mapping or reading kernel_page_tables debugfs file.
14 */
15static inline int note_kasan_page_table(struct mm_walk *walk,
16 unsigned long addr)
17{
18 struct ptdump_state *st = walk->private;
19
20 st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));
21
22 walk->action = ACTION_CONTINUE;
23
24 return 0;
25}
26#endif
27
28static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
29 unsigned long next, struct mm_walk *walk)
30{
31 struct ptdump_state *st = walk->private;
32 pgd_t val = READ_ONCE(*pgd);
33
34#if CONFIG_PGTABLE_LEVELS > 4 && defined(CONFIG_KASAN)
35 if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
36 return note_kasan_page_table(walk, addr);
37#endif
38
39 if (pgd_leaf(val))
40 st->note_page(st, addr, 0, pgd_val(val));
41
42 return 0;
43}
44
45static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
46 unsigned long next, struct mm_walk *walk)
47{
48 struct ptdump_state *st = walk->private;
49 p4d_t val = READ_ONCE(*p4d);
50
51#if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN)
52 if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
53 return note_kasan_page_table(walk, addr);
54#endif
55
56 if (p4d_leaf(val))
57 st->note_page(st, addr, 1, p4d_val(val));
58
59 return 0;
60}
61
62static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
63 unsigned long next, struct mm_walk *walk)
64{
65 struct ptdump_state *st = walk->private;
66 pud_t val = READ_ONCE(*pud);
67
68#if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN)
69 if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
70 return note_kasan_page_table(walk, addr);
71#endif
72
73 if (pud_leaf(val))
74 st->note_page(st, addr, 2, pud_val(val));
75
76 return 0;
77}
78
79static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
80 unsigned long next, struct mm_walk *walk)
81{
82 struct ptdump_state *st = walk->private;
83 pmd_t val = READ_ONCE(*pmd);
84
85#if defined(CONFIG_KASAN)
86 if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
87 return note_kasan_page_table(walk, addr);
88#endif
89
90 if (pmd_leaf(val))
91 st->note_page(st, addr, 3, pmd_val(val));
92
93 return 0;
94}
95
96static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
97 unsigned long next, struct mm_walk *walk)
98{
99 struct ptdump_state *st = walk->private;
100
101 st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte)));
102
103 return 0;
104}
105
106static int ptdump_hole(unsigned long addr, unsigned long next,
107 int depth, struct mm_walk *walk)
108{
109 struct ptdump_state *st = walk->private;
110
111 st->note_page(st, addr, depth, 0);
112
113 return 0;
114}
115
116static const struct mm_walk_ops ptdump_ops = {
117 .pgd_entry = ptdump_pgd_entry,
118 .p4d_entry = ptdump_p4d_entry,
119 .pud_entry = ptdump_pud_entry,
120 .pmd_entry = ptdump_pmd_entry,
121 .pte_entry = ptdump_pte_entry,
122 .pte_hole = ptdump_hole,
123};
124
125void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
126{
127 const struct ptdump_range *range = st->range;
128
129 down_read(&mm->mmap_sem);
130 while (range->start != range->end) {
131 walk_page_range_novma(mm, range->start, range->end,
132 &ptdump_ops, pgd, st);
133 range++;
134 }
135 up_read(&mm->mmap_sem);
136
137 /* Flush out the last page */
138 st->note_page(st, 0, -1, 0);
139}