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		walk->action = ACTION_CONTINUE;
 46	}
 47
 48	return 0;
 49}
 50
 51static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
 52			    unsigned long next, struct mm_walk *walk)
 53{
 54	struct ptdump_state *st = walk->private;
 55	p4d_t val = READ_ONCE(*p4d);
 56
 57#if CONFIG_PGTABLE_LEVELS > 3 && \
 58		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
 59	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
 60		return note_kasan_page_table(walk, addr);
 61#endif
 62
 63	if (st->effective_prot)
 64		st->effective_prot(st, 1, p4d_val(val));
 65
 66	if (p4d_leaf(val)) {
 67		st->note_page(st, addr, 1, p4d_val(val));
 68		walk->action = ACTION_CONTINUE;
 69	}
 70
 71	return 0;
 72}
 73
 74static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
 75			    unsigned long next, struct mm_walk *walk)
 76{
 77	struct ptdump_state *st = walk->private;
 78	pud_t val = READ_ONCE(*pud);
 79
 80#if CONFIG_PGTABLE_LEVELS > 2 && \
 81		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
 82	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
 83		return note_kasan_page_table(walk, addr);
 84#endif
 85
 86	if (st->effective_prot)
 87		st->effective_prot(st, 2, pud_val(val));
 88
 89	if (pud_leaf(val)) {
 90		st->note_page(st, addr, 2, pud_val(val));
 91		walk->action = ACTION_CONTINUE;
 92	}
 93
 94	return 0;
 95}
 96
 97static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
 98			    unsigned long next, struct mm_walk *walk)
 99{
100	struct ptdump_state *st = walk->private;
101	pmd_t val = READ_ONCE(*pmd);
102
103#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
104	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
105		return note_kasan_page_table(walk, addr);
106#endif
107
108	if (st->effective_prot)
109		st->effective_prot(st, 3, pmd_val(val));
110	if (pmd_leaf(val)) {
111		st->note_page(st, addr, 3, pmd_val(val));
112		walk->action = ACTION_CONTINUE;
113	}
114
115	return 0;
116}
117
118static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
119			    unsigned long next, struct mm_walk *walk)
120{
121	struct ptdump_state *st = walk->private;
122	pte_t val = ptep_get(pte);
123
124	if (st->effective_prot)
125		st->effective_prot(st, 4, pte_val(val));
126
127	st->note_page(st, addr, 4, pte_val(val));
128
129	return 0;
130}
131
132static int ptdump_hole(unsigned long addr, unsigned long next,
133		       int depth, struct mm_walk *walk)
134{
135	struct ptdump_state *st = walk->private;
136
137	st->note_page(st, addr, depth, 0);
138
139	return 0;
140}
141
142static const struct mm_walk_ops ptdump_ops = {
143	.pgd_entry	= ptdump_pgd_entry,
144	.p4d_entry	= ptdump_p4d_entry,
145	.pud_entry	= ptdump_pud_entry,
146	.pmd_entry	= ptdump_pmd_entry,
147	.pte_entry	= ptdump_pte_entry,
148	.pte_hole	= ptdump_hole,
149};
150
151void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
152{
153	const struct ptdump_range *range = st->range;
154
155	mmap_write_lock(mm);
156	while (range->start != range->end) {
157		walk_page_range_novma(mm, range->start, range->end,
158				      &ptdump_ops, pgd, st);
159		range++;
160	}
161	mmap_write_unlock(mm);
162
163	/* Flush out the last page */
164	st->note_page(st, 0, -1, 0);
165}