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 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
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 && \
35 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
36 if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
37 return note_kasan_page_table(walk, addr);
38 #endif
39
40 if (st->effective_prot)
41 st->effective_prot(st, 0, pgd_val(val));
42
43 if (pgd_leaf(val))
44 st->note_page(st, addr, 0, pgd_val(val));
45
46 return 0;
47 }
48
ptdump_p4d_entry(p4d_t * p4d,unsigned long addr,unsigned long next,struct mm_walk * walk)49 static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
50 unsigned long next, struct mm_walk *walk)
51 {
52 struct ptdump_state *st = walk->private;
53 p4d_t val = READ_ONCE(*p4d);
54
55 #if CONFIG_PGTABLE_LEVELS > 3 && \
56 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
57 if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
58 return note_kasan_page_table(walk, addr);
59 #endif
60
61 if (st->effective_prot)
62 st->effective_prot(st, 1, p4d_val(val));
63
64 if (p4d_leaf(val))
65 st->note_page(st, addr, 1, p4d_val(val));
66
67 return 0;
68 }
69
ptdump_pud_entry(pud_t * pud,unsigned long addr,unsigned long next,struct mm_walk * walk)70 static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
71 unsigned long next, struct mm_walk *walk)
72 {
73 struct ptdump_state *st = walk->private;
74 pud_t val = READ_ONCE(*pud);
75
76 #if CONFIG_PGTABLE_LEVELS > 2 && \
77 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
78 if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
79 return note_kasan_page_table(walk, addr);
80 #endif
81
82 if (st->effective_prot)
83 st->effective_prot(st, 2, pud_val(val));
84
85 if (pud_leaf(val))
86 st->note_page(st, addr, 2, pud_val(val));
87
88 return 0;
89 }
90
ptdump_pmd_entry(pmd_t * pmd,unsigned long addr,unsigned long next,struct mm_walk * walk)91 static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
92 unsigned long next, struct mm_walk *walk)
93 {
94 struct ptdump_state *st = walk->private;
95 pmd_t val = READ_ONCE(*pmd);
96
97 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
98 if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
99 return note_kasan_page_table(walk, addr);
100 #endif
101
102 if (st->effective_prot)
103 st->effective_prot(st, 3, pmd_val(val));
104 if (pmd_leaf(val))
105 st->note_page(st, addr, 3, pmd_val(val));
106
107 return 0;
108 }
109
ptdump_pte_entry(pte_t * pte,unsigned long addr,unsigned long next,struct mm_walk * walk)110 static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
111 unsigned long next, struct mm_walk *walk)
112 {
113 struct ptdump_state *st = walk->private;
114 pte_t val = ptep_get(pte);
115
116 if (st->effective_prot)
117 st->effective_prot(st, 4, pte_val(val));
118
119 st->note_page(st, addr, 4, pte_val(val));
120
121 return 0;
122 }
123
ptdump_hole(unsigned long addr,unsigned long next,int depth,struct mm_walk * walk)124 static int ptdump_hole(unsigned long addr, unsigned long next,
125 int depth, struct mm_walk *walk)
126 {
127 struct ptdump_state *st = walk->private;
128
129 st->note_page(st, addr, depth, 0);
130
131 return 0;
132 }
133
134 static const struct mm_walk_ops ptdump_ops = {
135 .pgd_entry = ptdump_pgd_entry,
136 .p4d_entry = ptdump_p4d_entry,
137 .pud_entry = ptdump_pud_entry,
138 .pmd_entry = ptdump_pmd_entry,
139 .pte_entry = ptdump_pte_entry,
140 .pte_hole = ptdump_hole,
141 };
142
ptdump_walk_pgd(struct ptdump_state * st,struct mm_struct * mm,pgd_t * pgd)143 void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
144 {
145 const struct ptdump_range *range = st->range;
146
147 mmap_read_lock(mm);
148 while (range->start != range->end) {
149 walk_page_range_novma(mm, range->start, range->end,
150 &ptdump_ops, pgd, st);
151 range++;
152 }
153 mmap_read_unlock(mm);
154
155 /* Flush out the last page */
156 st->note_page(st, 0, -1, 0);
157 }
158
