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 walk->action = ACTION_CONTINUE; 46 } 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 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 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 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 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); 102 103 #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 } 117 118 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; 122 pte_t val = ptep_get_lockless(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 } 131 132 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; 136 137 st->note_page(st, addr, depth, 0); 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 }; 150 151 void 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 } 166