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 */ 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 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 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 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 49 static 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 70 static 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 91 static 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 } 109 110 static 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 } 123 124 static 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 } 133 134 static 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 }; 142 143 void 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