[linux.git] / mm / ptdump.c

// SPDX-License-Identifier: GPL-2.0

#include <linux/pagewalk.h>
#include <linux/ptdump.h>
#include <linux/kasan.h>

#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
/*
 * This is an optimization for KASAN=y case. Since all kasan page tables
 * eventually point to the kasan_early_shadow_page we could call note_page()
 * right away without walking through lower level page tables. This saves
 * us dozens of seconds (minutes for 5-level config) while checking for
 * W+X mapping or reading kernel_page_tables debugfs file.
 */
static inline int note_kasan_page_table(struct mm_walk *walk,
					unsigned long addr)
{
	struct ptdump_state *st = walk->private;

	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));

	walk->action = ACTION_CONTINUE;

	return 0;
}
#endif

static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pgd_t val = READ_ONCE(*pgd);

#if CONFIG_PGTABLE_LEVELS > 4 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot)
		st->effective_prot(st, 0, pgd_val(val));

	if (pgd_leaf(val)) {
		st->note_page(st, addr, 0, pgd_val(val));
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	p4d_t val = READ_ONCE(*p4d);

#if CONFIG_PGTABLE_LEVELS > 3 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot)
		st->effective_prot(st, 1, p4d_val(val));

	if (p4d_leaf(val)) {
		st->note_page(st, addr, 1, p4d_val(val));
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pud_t val = READ_ONCE(*pud);

#if CONFIG_PGTABLE_LEVELS > 2 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot)
		st->effective_prot(st, 2, pud_val(val));

	if (pud_leaf(val)) {
		st->note_page(st, addr, 2, pud_val(val));
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pmd_t val = READ_ONCE(*pmd);

#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot)
		st->effective_prot(st, 3, pmd_val(val));
	if (pmd_leaf(val)) {
		st->note_page(st, addr, 3, pmd_val(val));
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pte_t val = ptep_get(pte);

	if (st->effective_prot)
		st->effective_prot(st, 4, pte_val(val));

	st->note_page(st, addr, 4, pte_val(val));

	return 0;
}

static int ptdump_hole(unsigned long addr, unsigned long next,
		       int depth, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;

	st->note_page(st, addr, depth, 0);

	return 0;
}

static const struct mm_walk_ops ptdump_ops = {
	.pgd_entry	= ptdump_pgd_entry,
	.p4d_entry	= ptdump_p4d_entry,
	.pud_entry	= ptdump_pud_entry,
	.pmd_entry	= ptdump_pmd_entry,
	.pte_entry	= ptdump_pte_entry,
	.pte_hole	= ptdump_hole,
};

void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
{
	const struct ptdump_range *range = st->range;

	mmap_read_lock(mm);
	while (range->start != range->end) {
		walk_page_range_novma(mm, range->start, range->end,
				      &ptdump_ops, pgd, st);
		range++;
	}
	mmap_read_unlock(mm);

	/* Flush out the last page */
	st->note_page(st, 0, -1, 0);
}
Commit	Line	Data
30d621f6 SP	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	#include <linux/pagewalk.h>
	4	#include <linux/ptdump.h>
	5	#include <linux/kasan.h>
	6
0fea6e9a	7	#if defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS)
30d621f6 SP	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	*/
	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
f8f0d0b6	20	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));
30d621f6 SP	21
	22	walk->action = ACTION_CONTINUE;
	23
	24	return 0;
	25	}
	26	#endif
	27
	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
0fea6e9a AK	34	#if CONFIG_PGTABLE_LEVELS > 4 && \
0fea6e9a AK	35	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
30d621f6 SP	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
1494e0c3 SP	40	if (st->effective_prot)
	41	st->effective_prot(st, 0, pgd_val(val));
	42
d8d55f56	43	if (pgd_leaf(val)) {
f8f0d0b6	44	st->note_page(st, addr, 0, pgd_val(val));
d8d55f56 MS	45	walk->action = ACTION_CONTINUE;
d8d55f56 MS	46	}
30d621f6 SP	47
	48	return 0;
	49	}
	50
	51	static 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
0fea6e9a AK	57	#if CONFIG_PGTABLE_LEVELS > 3 && \
0fea6e9a AK	58	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
30d621f6 SP	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
1494e0c3 SP	63	if (st->effective_prot)
	64	st->effective_prot(st, 1, p4d_val(val));
	65
d8d55f56	66	if (p4d_leaf(val)) {
f8f0d0b6	67	st->note_page(st, addr, 1, p4d_val(val));
d8d55f56 MS	68	walk->action = ACTION_CONTINUE;
d8d55f56 MS	69	}
30d621f6 SP	70
	71	return 0;
	72	}
	73
	74	static 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
0fea6e9a AK	80	#if CONFIG_PGTABLE_LEVELS > 2 && \
0fea6e9a AK	81	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
30d621f6 SP	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
1494e0c3 SP	86	if (st->effective_prot)
	87	st->effective_prot(st, 2, pud_val(val));
	88
d8d55f56	89	if (pud_leaf(val)) {
f8f0d0b6	90	st->note_page(st, addr, 2, pud_val(val));
d8d55f56 MS	91	walk->action = ACTION_CONTINUE;
d8d55f56 MS	92	}
30d621f6 SP	93
	94	return 0;
	95	}
	96
	97	static 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
0fea6e9a	103	#if defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS)
30d621f6 SP	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
1494e0c3 SP	108	if (st->effective_prot)
1494e0c3 SP	109	st->effective_prot(st, 3, pmd_val(val));
d8d55f56	110	if (pmd_leaf(val)) {
f8f0d0b6	111	st->note_page(st, addr, 3, pmd_val(val));
d8d55f56 MS	112	walk->action = ACTION_CONTINUE;
d8d55f56 MS	113	}
30d621f6 SP	114
	115	return 0;
	116	}
	117
	118	static 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;
45837691	122	pte_t val = ptep_get(pte);
1494e0c3 SP	123
	124	if (st->effective_prot)
	125	st->effective_prot(st, 4, pte_val(val));
30d621f6	126
1494e0c3	127	st->note_page(st, addr, 4, pte_val(val));
30d621f6 SP	128
	129	return 0;
	130	}
	131
	132	static 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
f8f0d0b6	137	st->note_page(st, addr, depth, 0);
30d621f6 SP	138
	139	return 0;
	140	}
	141
	142	static 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
e47690d7	151	void ptdump_walk_pgd(struct ptdump_state st, struct mm_struct mm, pgd_t *pgd)
30d621f6 SP	152	{
	153	const struct ptdump_range *range = st->range;
	154
d8ed45c5	155	mmap_read_lock(mm);
30d621f6 SP	156	while (range->start != range->end) {
30d621f6 SP	157	walk_page_range_novma(mm, range->start, range->end,
e47690d7	158	&ptdump_ops, pgd, st);
30d621f6 SP	159	range++;
30d621f6 SP	160	}
d8ed45c5	161	mmap_read_unlock(mm);
30d621f6 SP	162
30d621f6 SP	163	/* Flush out the last page */
f8f0d0b6	164	st->note_page(st, 0, -1, 0);
30d621f6	165	}