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 #ifdef CONFIG_KASAN 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 && defined(CONFIG_KASAN) 35 if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d))) 36 return note_kasan_page_table(walk, addr); 37 #endif 38 39 if (st->effective_prot) 40 st->effective_prot(st, 0, pgd_val(val)); 41 42 if (pgd_leaf(val)) 43 st->note_page(st, addr, 0, pgd_val(val)); 44 45 return 0; 46 } 47 48 static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr, 49 unsigned long next, struct mm_walk *walk) 50 { 51 struct ptdump_state *st = walk->private; 52 p4d_t val = READ_ONCE(*p4d); 53 54 #if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN) 55 if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud))) 56 return note_kasan_page_table(walk, addr); 57 #endif 58 59 if (st->effective_prot) 60 st->effective_prot(st, 1, p4d_val(val)); 61 62 if (p4d_leaf(val)) 63 st->note_page(st, addr, 1, p4d_val(val)); 64 65 return 0; 66 } 67 68 static int ptdump_pud_entry(pud_t *pud, unsigned long addr, 69 unsigned long next, struct mm_walk *walk) 70 { 71 struct ptdump_state *st = walk->private; 72 pud_t val = READ_ONCE(*pud); 73 74 #if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN) 75 if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd))) 76 return note_kasan_page_table(walk, addr); 77 #endif 78 79 if (st->effective_prot) 80 st->effective_prot(st, 2, pud_val(val)); 81 82 if (pud_leaf(val)) 83 st->note_page(st, addr, 2, pud_val(val)); 84 85 return 0; 86 } 87 88 static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr, 89 unsigned long next, struct mm_walk *walk) 90 { 91 struct ptdump_state *st = walk->private; 92 pmd_t val = READ_ONCE(*pmd); 93 94 #if defined(CONFIG_KASAN) 95 if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte))) 96 return note_kasan_page_table(walk, addr); 97 #endif 98 99 if (st->effective_prot) 100 st->effective_prot(st, 3, pmd_val(val)); 101 if (pmd_leaf(val)) 102 st->note_page(st, addr, 3, pmd_val(val)); 103 104 return 0; 105 } 106 107 static int ptdump_pte_entry(pte_t *pte, unsigned long addr, 108 unsigned long next, struct mm_walk *walk) 109 { 110 struct ptdump_state *st = walk->private; 111 pte_t val = READ_ONCE(*pte); 112 113 if (st->effective_prot) 114 st->effective_prot(st, 4, pte_val(val)); 115 116 st->note_page(st, addr, 4, pte_val(val)); 117 118 return 0; 119 } 120 121 static int ptdump_hole(unsigned long addr, unsigned long next, 122 int depth, struct mm_walk *walk) 123 { 124 struct ptdump_state *st = walk->private; 125 126 st->note_page(st, addr, depth, 0); 127 128 return 0; 129 } 130 131 static const struct mm_walk_ops ptdump_ops = { 132 .pgd_entry = ptdump_pgd_entry, 133 .p4d_entry = ptdump_p4d_entry, 134 .pud_entry = ptdump_pud_entry, 135 .pmd_entry = ptdump_pmd_entry, 136 .pte_entry = ptdump_pte_entry, 137 .pte_hole = ptdump_hole, 138 }; 139 140 void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd) 141 { 142 const struct ptdump_range *range = st->range; 143 144 down_read(&mm->mmap_sem); 145 while (range->start != range->end) { 146 walk_page_range_novma(mm, range->start, range->end, 147 &ptdump_ops, pgd, st); 148 range++; 149 } 150 up_read(&mm->mmap_sem); 151 152 /* Flush out the last page */ 153 st->note_page(st, 0, -1, 0); 154 } 155