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