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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 (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
48static 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
68static 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
88static 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
107static 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
121static 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
131static 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
140void 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}
1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/pagewalk.h>
4#include <linux/debugfs.h>
5#include <linux/ptdump.h>
6#include <linux/kasan.h>
7
8#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
9/*
10 * This is an optimization for KASAN=y case. Since all kasan page tables
11 * eventually point to the kasan_early_shadow_page we could call note_page()
12 * right away without walking through lower level page tables. This saves
13 * us dozens of seconds (minutes for 5-level config) while checking for
14 * W+X mapping or reading kernel_page_tables debugfs file.
15 */
16static inline int note_kasan_page_table(struct mm_walk *walk,
17 unsigned long addr)
18{
19 struct ptdump_state *st = walk->private;
20
21 st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));
22
23 walk->action = ACTION_CONTINUE;
24
25 return 0;
26}
27#endif
28
29static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
30 unsigned long next, struct mm_walk *walk)
31{
32 struct ptdump_state *st = walk->private;
33 pgd_t val = READ_ONCE(*pgd);
34
35#if CONFIG_PGTABLE_LEVELS > 4 && \
36 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
37 if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
38 return note_kasan_page_table(walk, addr);
39#endif
40
41 if (st->effective_prot)
42 st->effective_prot(st, 0, pgd_val(val));
43
44 if (pgd_leaf(val)) {
45 st->note_page(st, addr, 0, pgd_val(val));
46 walk->action = ACTION_CONTINUE;
47 }
48
49 return 0;
50}
51
52static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
53 unsigned long next, struct mm_walk *walk)
54{
55 struct ptdump_state *st = walk->private;
56 p4d_t val = READ_ONCE(*p4d);
57
58#if CONFIG_PGTABLE_LEVELS > 3 && \
59 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
60 if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
61 return note_kasan_page_table(walk, addr);
62#endif
63
64 if (st->effective_prot)
65 st->effective_prot(st, 1, p4d_val(val));
66
67 if (p4d_leaf(val)) {
68 st->note_page(st, addr, 1, p4d_val(val));
69 walk->action = ACTION_CONTINUE;
70 }
71
72 return 0;
73}
74
75static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
76 unsigned long next, struct mm_walk *walk)
77{
78 struct ptdump_state *st = walk->private;
79 pud_t val = READ_ONCE(*pud);
80
81#if CONFIG_PGTABLE_LEVELS > 2 && \
82 (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
83 if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
84 return note_kasan_page_table(walk, addr);
85#endif
86
87 if (st->effective_prot)
88 st->effective_prot(st, 2, pud_val(val));
89
90 if (pud_leaf(val)) {
91 st->note_page(st, addr, 2, pud_val(val));
92 walk->action = ACTION_CONTINUE;
93 }
94
95 return 0;
96}
97
98static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
99 unsigned long next, struct mm_walk *walk)
100{
101 struct ptdump_state *st = walk->private;
102 pmd_t val = READ_ONCE(*pmd);
103
104#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
105 if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
106 return note_kasan_page_table(walk, addr);
107#endif
108
109 if (st->effective_prot)
110 st->effective_prot(st, 3, pmd_val(val));
111 if (pmd_leaf(val)) {
112 st->note_page(st, addr, 3, pmd_val(val));
113 walk->action = ACTION_CONTINUE;
114 }
115
116 return 0;
117}
118
119static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
120 unsigned long next, struct mm_walk *walk)
121{
122 struct ptdump_state *st = walk->private;
123 pte_t val = ptep_get_lockless(pte);
124
125 if (st->effective_prot)
126 st->effective_prot(st, 4, pte_val(val));
127
128 st->note_page(st, addr, 4, pte_val(val));
129
130 return 0;
131}
132
133static int ptdump_hole(unsigned long addr, unsigned long next,
134 int depth, struct mm_walk *walk)
135{
136 struct ptdump_state *st = walk->private;
137
138 st->note_page(st, addr, depth, 0);
139
140 return 0;
141}
142
143static const struct mm_walk_ops ptdump_ops = {
144 .pgd_entry = ptdump_pgd_entry,
145 .p4d_entry = ptdump_p4d_entry,
146 .pud_entry = ptdump_pud_entry,
147 .pmd_entry = ptdump_pmd_entry,
148 .pte_entry = ptdump_pte_entry,
149 .pte_hole = ptdump_hole,
150};
151
152void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
153{
154 const struct ptdump_range *range = st->range;
155
156 mmap_write_lock(mm);
157 while (range->start != range->end) {
158 walk_page_range_novma(mm, range->start, range->end,
159 &ptdump_ops, pgd, st);
160 range++;
161 }
162 mmap_write_unlock(mm);
163
164 /* Flush out the last page */
165 st->note_page(st, 0, -1, 0);
166}
167
168static int check_wx_show(struct seq_file *m, void *v)
169{
170 if (ptdump_check_wx())
171 seq_puts(m, "SUCCESS\n");
172 else
173 seq_puts(m, "FAILED\n");
174
175 return 0;
176}
177
178DEFINE_SHOW_ATTRIBUTE(check_wx);
179
180static int ptdump_debugfs_init(void)
181{
182 debugfs_create_file("check_wx_pages", 0400, NULL, NULL, &check_wx_fops);
183
184 return 0;
185}
186
187device_initcall(ptdump_debugfs_init);