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 */
note_kasan_page_table(struct mm_walk * walk,unsigned long addr)15 static 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
ptdump_pgd_entry(pgd_t * pgd,unsigned long addr,unsigned long next,struct mm_walk * walk)28 static 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 (st->effective_prot)
40 st->effective_prot(st, 0, pgd_val(val));
41
42 if (pgd_leaf(val))
43 st->note_page(st, addr, 0, pgd_val(val));
44
45 return 0;
46 }
47
ptdump_p4d_entry(p4d_t * p4d,unsigned long addr,unsigned long next,struct mm_walk * walk)48 static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
49 unsigned long next, struct mm_walk *walk)
50 {
51 struct ptdump_state *st = walk->private;
52 p4d_t val = READ_ONCE(*p4d);
53
54 #if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN)
55 if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
56 return note_kasan_page_table(walk, addr);
57 #endif
58
59 if (st->effective_prot)
60 st->effective_prot(st, 1, p4d_val(val));
61
62 if (p4d_leaf(val))
63 st->note_page(st, addr, 1, p4d_val(val));
64
65 return 0;
66 }
67
ptdump_pud_entry(pud_t * pud,unsigned long addr,unsigned long next,struct mm_walk * walk)68 static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
69 unsigned long next, struct mm_walk *walk)
70 {
71 struct ptdump_state *st = walk->private;
72 pud_t val = READ_ONCE(*pud);
73
74 #if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN)
75 if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
76 return note_kasan_page_table(walk, addr);
77 #endif
78
79 if (st->effective_prot)
80 st->effective_prot(st, 2, pud_val(val));
81
82 if (pud_leaf(val))
83 st->note_page(st, addr, 2, pud_val(val));
84
85 return 0;
86 }
87
ptdump_pmd_entry(pmd_t * pmd,unsigned long addr,unsigned long next,struct mm_walk * walk)88 static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
89 unsigned long next, struct mm_walk *walk)
90 {
91 struct ptdump_state *st = walk->private;
92 pmd_t val = READ_ONCE(*pmd);
93
94 #if defined(CONFIG_KASAN)
95 if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
96 return note_kasan_page_table(walk, addr);
97 #endif
98
99 if (st->effective_prot)
100 st->effective_prot(st, 3, pmd_val(val));
101 if (pmd_leaf(val))
102 st->note_page(st, addr, 3, pmd_val(val));
103
104 return 0;
105 }
106
ptdump_pte_entry(pte_t * pte,unsigned long addr,unsigned long next,struct mm_walk * walk)107 static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
108 unsigned long next, struct mm_walk *walk)
109 {
110 struct ptdump_state *st = walk->private;
111 pte_t val = READ_ONCE(*pte);
112
113 if (st->effective_prot)
114 st->effective_prot(st, 4, pte_val(val));
115
116 st->note_page(st, addr, 4, pte_val(val));
117
118 return 0;
119 }
120
ptdump_hole(unsigned long addr,unsigned long next,int depth,struct mm_walk * walk)121 static int ptdump_hole(unsigned long addr, unsigned long next,
122 int depth, struct mm_walk *walk)
123 {
124 struct ptdump_state *st = walk->private;
125
126 st->note_page(st, addr, depth, 0);
127
128 return 0;
129 }
130
131 static const struct mm_walk_ops ptdump_ops = {
132 .pgd_entry = ptdump_pgd_entry,
133 .p4d_entry = ptdump_p4d_entry,
134 .pud_entry = ptdump_pud_entry,
135 .pmd_entry = ptdump_pmd_entry,
136 .pte_entry = ptdump_pte_entry,
137 .pte_hole = ptdump_hole,
138 };
139
ptdump_walk_pgd(struct ptdump_state * st,struct mm_struct * mm,pgd_t * pgd)140 void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
141 {
142 const struct ptdump_range *range = st->range;
143
144 mmap_read_lock(mm);
145 while (range->start != range->end) {
146 walk_page_range_novma(mm, range->start, range->end,
147 &ptdump_ops, pgd, st);
148 range++;
149 }
150 mmap_read_unlock(mm);
151
152 /* Flush out the last page */
153 st->note_page(st, 0, -1, 0);
154 }
155
