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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 #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_write_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_write_unlock(mm);
154 
155 	/* Flush out the last page */
156 	st->note_page(st, 0, -1, 0);
157 }
158