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 */
 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 && \
 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
 49static 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
 70static 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
 91static 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
110static 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
124static 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
134static 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
143void 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}