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 ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page, 8 unsigned long addr, unsigned long end) 9 { 10 addr &= PMD_MASK; 11 for (; addr < end; addr += PMD_SIZE) { 12 pmd_t *pmd = pmd_page + pmd_index(addr); 13 14 if (pmd_present(*pmd)) 15 continue; 16 17 set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag)); 18 } 19 } 20 21 static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 22 unsigned long addr, unsigned long end) 23 { 24 unsigned long next; 25 26 for (; addr < end; addr = next) { 27 pud_t *pud = pud_page + pud_index(addr); 28 pmd_t *pmd; 29 bool use_gbpage; 30 31 next = (addr & PUD_MASK) + PUD_SIZE; 32 if (next > end) 33 next = end; 34 35 /* if this is already a gbpage, this portion is already mapped */ 36 if (pud_large(*pud)) 37 continue; 38 39 /* Is using a gbpage allowed? */ 40 use_gbpage = info->direct_gbpages; 41 42 /* Don't use gbpage if it maps more than the requested region. */ 43 /* at the begining: */ 44 use_gbpage &= ((addr & ~PUD_MASK) == 0); 45 /* ... or at the end: */ 46 use_gbpage &= ((next & ~PUD_MASK) == 0); 47 48 /* Never overwrite existing mappings */ 49 use_gbpage &= !pud_present(*pud); 50 51 if (use_gbpage) { 52 pud_t pudval; 53 54 pudval = __pud((addr - info->offset) | info->page_flag); 55 set_pud(pud, pudval); 56 continue; 57 } 58 59 if (pud_present(*pud)) { 60 pmd = pmd_offset(pud, 0); 61 ident_pmd_init(info, pmd, addr, next); 62 continue; 63 } 64 pmd = (pmd_t *)info->alloc_pgt_page(info->context); 65 if (!pmd) 66 return -ENOMEM; 67 ident_pmd_init(info, pmd, addr, next); 68 set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); 69 } 70 71 return 0; 72 } 73 74 static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, 75 unsigned long addr, unsigned long end) 76 { 77 unsigned long next; 78 int result; 79 80 for (; addr < end; addr = next) { 81 p4d_t *p4d = p4d_page + p4d_index(addr); 82 pud_t *pud; 83 84 next = (addr & P4D_MASK) + P4D_SIZE; 85 if (next > end) 86 next = end; 87 88 if (p4d_present(*p4d)) { 89 pud = pud_offset(p4d, 0); 90 result = ident_pud_init(info, pud, addr, next); 91 if (result) 92 return result; 93 94 continue; 95 } 96 pud = (pud_t *)info->alloc_pgt_page(info->context); 97 if (!pud) 98 return -ENOMEM; 99 100 result = ident_pud_init(info, pud, addr, next); 101 if (result) 102 return result; 103 104 set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); 105 } 106 107 return 0; 108 } 109 110 int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, 111 unsigned long pstart, unsigned long pend) 112 { 113 unsigned long addr = pstart + info->offset; 114 unsigned long end = pend + info->offset; 115 unsigned long next; 116 int result; 117 118 /* Set the default pagetable flags if not supplied */ 119 if (!info->kernpg_flag) 120 info->kernpg_flag = _KERNPG_TABLE; 121 122 /* Filter out unsupported __PAGE_KERNEL_* bits: */ 123 info->kernpg_flag &= __default_kernel_pte_mask; 124 125 for (; addr < end; addr = next) { 126 pgd_t *pgd = pgd_page + pgd_index(addr); 127 p4d_t *p4d; 128 129 next = (addr & PGDIR_MASK) + PGDIR_SIZE; 130 if (next > end) 131 next = end; 132 133 if (pgd_present(*pgd)) { 134 p4d = p4d_offset(pgd, 0); 135 result = ident_p4d_init(info, p4d, addr, next); 136 if (result) 137 return result; 138 continue; 139 } 140 141 p4d = (p4d_t *)info->alloc_pgt_page(info->context); 142 if (!p4d) 143 return -ENOMEM; 144 result = ident_p4d_init(info, p4d, addr, next); 145 if (result) 146 return result; 147 if (pgtable_l5_enabled()) { 148 set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag)); 149 } else { 150 /* 151 * With p4d folded, pgd is equal to p4d. 152 * The pgd entry has to point to the pud page table in this case. 153 */ 154 pud_t *pud = pud_offset(p4d, 0); 155 set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag)); 156 } 157 } 158 159 return 0; 160 } 161