1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Helper routines for building identity mapping page tables. This is 4 * included by both the compressed kernel and the regular kernel. 5 */ 6 7 static void free_pte(struct x86_mapping_info *info, pmd_t *pmd) 8 { 9 pte_t *pte = pte_offset_kernel(pmd, 0); 10 11 info->free_pgt_page(pte, info->context); 12 } 13 14 static void free_pmd(struct x86_mapping_info *info, pud_t *pud) 15 { 16 pmd_t *pmd = pmd_offset(pud, 0); 17 int i; 18 19 for (i = 0; i < PTRS_PER_PMD; i++) { 20 if (!pmd_present(pmd[i])) 21 continue; 22 23 if (pmd_leaf(pmd[i])) 24 continue; 25 26 free_pte(info, &pmd[i]); 27 } 28 29 info->free_pgt_page(pmd, info->context); 30 } 31 32 static void free_pud(struct x86_mapping_info *info, p4d_t *p4d) 33 { 34 pud_t *pud = pud_offset(p4d, 0); 35 int i; 36 37 for (i = 0; i < PTRS_PER_PUD; i++) { 38 if (!pud_present(pud[i])) 39 continue; 40 41 if (pud_leaf(pud[i])) 42 continue; 43 44 free_pmd(info, &pud[i]); 45 } 46 47 info->free_pgt_page(pud, info->context); 48 } 49 50 static void free_p4d(struct x86_mapping_info *info, pgd_t *pgd) 51 { 52 p4d_t *p4d = p4d_offset(pgd, 0); 53 int i; 54 55 for (i = 0; i < PTRS_PER_P4D; i++) { 56 if (!p4d_present(p4d[i])) 57 continue; 58 59 free_pud(info, &p4d[i]); 60 } 61 62 if (pgtable_l5_enabled()) 63 info->free_pgt_page(p4d, info->context); 64 } 65 66 void kernel_ident_mapping_free(struct x86_mapping_info *info, pgd_t *pgd) 67 { 68 int i; 69 70 for (i = 0; i < PTRS_PER_PGD; i++) { 71 if (!pgd_present(pgd[i])) 72 continue; 73 74 free_p4d(info, &pgd[i]); 75 } 76 77 info->free_pgt_page(pgd, info->context); 78 } 79 80 static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page, 81 unsigned long addr, unsigned long end) 82 { 83 addr &= PMD_MASK; 84 for (; addr < end; addr += PMD_SIZE) { 85 pmd_t *pmd = pmd_page + pmd_index(addr); 86 87 if (pmd_present(*pmd)) 88 continue; 89 90 set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag)); 91 } 92 } 93 94 static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 95 unsigned long addr, unsigned long end) 96 { 97 unsigned long next; 98 99 for (; addr < end; addr = next) { 100 pud_t *pud = pud_page + pud_index(addr); 101 pmd_t *pmd; 102 103 next = (addr & PUD_MASK) + PUD_SIZE; 104 if (next > end) 105 next = end; 106 107 if (info->direct_gbpages) { 108 pud_t pudval; 109 110 if (pud_present(*pud)) 111 continue; 112 113 addr &= PUD_MASK; 114 pudval = __pud((addr - info->offset) | info->page_flag); 115 set_pud(pud, pudval); 116 continue; 117 } 118 119 if (pud_present(*pud)) { 120 pmd = pmd_offset(pud, 0); 121 ident_pmd_init(info, pmd, addr, next); 122 continue; 123 } 124 pmd = (pmd_t *)info->alloc_pgt_page(info->context); 125 if (!pmd) 126 return -ENOMEM; 127 ident_pmd_init(info, pmd, addr, next); 128 set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); 129 } 130 131 return 0; 132 } 133 134 static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, 135 unsigned long addr, unsigned long end) 136 { 137 unsigned long next; 138 int result; 139 140 for (; addr < end; addr = next) { 141 p4d_t *p4d = p4d_page + p4d_index(addr); 142 pud_t *pud; 143 144 next = (addr & P4D_MASK) + P4D_SIZE; 145 if (next > end) 146 next = end; 147 148 if (p4d_present(*p4d)) { 149 pud = pud_offset(p4d, 0); 150 result = ident_pud_init(info, pud, addr, next); 151 if (result) 152 return result; 153 154 continue; 155 } 156 pud = (pud_t *)info->alloc_pgt_page(info->context); 157 if (!pud) 158 return -ENOMEM; 159 160 result = ident_pud_init(info, pud, addr, next); 161 if (result) 162 return result; 163 164 set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); 165 } 166 167 return 0; 168 } 169 170 int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, 171 unsigned long pstart, unsigned long pend) 172 { 173 unsigned long addr = pstart + info->offset; 174 unsigned long end = pend + info->offset; 175 unsigned long next; 176 int result; 177 178 /* Set the default pagetable flags if not supplied */ 179 if (!info->kernpg_flag) 180 info->kernpg_flag = _KERNPG_TABLE; 181 182 /* Filter out unsupported __PAGE_KERNEL_* bits: */ 183 info->kernpg_flag &= __default_kernel_pte_mask; 184 185 for (; addr < end; addr = next) { 186 pgd_t *pgd = pgd_page + pgd_index(addr); 187 p4d_t *p4d; 188 189 next = (addr & PGDIR_MASK) + PGDIR_SIZE; 190 if (next > end) 191 next = end; 192 193 if (pgd_present(*pgd)) { 194 p4d = p4d_offset(pgd, 0); 195 result = ident_p4d_init(info, p4d, addr, next); 196 if (result) 197 return result; 198 continue; 199 } 200 201 p4d = (p4d_t *)info->alloc_pgt_page(info->context); 202 if (!p4d) 203 return -ENOMEM; 204 result = ident_p4d_init(info, p4d, addr, next); 205 if (result) 206 return result; 207 if (pgtable_l5_enabled()) { 208 set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag)); 209 } else { 210 /* 211 * With p4d folded, pgd is equal to p4d. 212 * The pgd entry has to point to the pud page table in this case. 213 */ 214 pud_t *pud = pud_offset(p4d, 0); 215 set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag)); 216 } 217 } 218 219 return 0; 220 } 221