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// SPDX-License-Identifier: GPL-2.0
#include <linux/pagewalk.h>
#include <linux/ptdump.h>
#include <linux/kasan.h>
#ifdef CONFIG_KASAN
/*
* 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)
if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
return note_kasan_page_table(walk, addr);
#endif
if (pgd_leaf(val))
st->note_page(st, addr, 0, pgd_val(val));
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)
if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
return note_kasan_page_table(walk, addr);
#endif
if (p4d_leaf(val))
st->note_page(st, addr, 1, p4d_val(val));
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)
if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
return note_kasan_page_table(walk, addr);
#endif
if (pud_leaf(val))
st->note_page(st, addr, 2, pud_val(val));
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)
if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
return note_kasan_page_table(walk, addr);
#endif
if (pmd_leaf(val))
st->note_page(st, addr, 3, pmd_val(val));
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;
st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte)));
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;
down_read(&mm->mmap_sem);
while (range->start != range->end) {
walk_page_range_novma(mm, range->start, range->end,
&ptdump_ops, pgd, st);
range++;
}
up_read(&mm->mmap_sem);
/* Flush out the last page */
st->note_page(st, 0, -1, 0);
}
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