LXR linux/mm/ptdump.c

   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}
 158