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 30 next = (addr & PUD_MASK) + PUD_SIZE; 31 if (next > end) 32 next = end; 33 34 if (info->direct_gbpages) { 35 pud_t pudval; 36 37 if (pud_present(*pud)) 38 continue; 39 40 addr &= PUD_MASK; 41 pudval = __pud((addr - info->offset) | info->page_flag); 42 set_pud(pud, pudval); 43 continue; 44 } 45 46 if (pud_present(*pud)) { 47 pmd = pmd_offset(pud, 0); 48 ident_pmd_init(info, pmd, addr, next); 49 continue; 50 } 51 pmd = (pmd_t *)info->alloc_pgt_page(info->context); 52 if (!pmd) 53 return -ENOMEM; 54 ident_pmd_init(info, pmd, addr, next); 55 set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); 56 } 57 58 return 0; 59 } 60 61 static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, 62 unsigned long addr, unsigned long end) 63 { 64 unsigned long next; 65 66 for (; addr < end; addr = next) { 67 p4d_t *p4d = p4d_page + p4d_index(addr); 68 pud_t *pud; 69 70 next = (addr & P4D_MASK) + P4D_SIZE; 71 if (next > end) 72 next = end; 73 74 if (p4d_present(*p4d)) { 75 pud = pud_offset(p4d, 0); 76 ident_pud_init(info, pud, addr, next); 77 continue; 78 } 79 pud = (pud_t *)info->alloc_pgt_page(info->context); 80 if (!pud) 81 return -ENOMEM; 82 ident_pud_init(info, pud, addr, next); 83 set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); 84 } 85 86 return 0; 87 } 88 89 int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, 90 unsigned long pstart, unsigned long pend) 91 { 92 unsigned long addr = pstart + info->offset; 93 unsigned long end = pend + info->offset; 94 unsigned long next; 95 int result; 96 97 /* Set the default pagetable flags if not supplied */ 98 if (!info->kernpg_flag) 99 info->kernpg_flag = _KERNPG_TABLE; 100 101 /* Filter out unsupported __PAGE_KERNEL_* bits: */ 102 info->kernpg_flag &= __default_kernel_pte_mask; 103 104 for (; addr < end; addr = next) { 105 pgd_t *pgd = pgd_page + pgd_index(addr); 106 p4d_t *p4d; 107 108 next = (addr & PGDIR_MASK) + PGDIR_SIZE; 109 if (next > end) 110 next = end; 111 112 if (pgd_present(*pgd)) { 113 p4d = p4d_offset(pgd, 0); 114 result = ident_p4d_init(info, p4d, addr, next); 115 if (result) 116 return result; 117 continue; 118 } 119 120 p4d = (p4d_t *)info->alloc_pgt_page(info->context); 121 if (!p4d) 122 return -ENOMEM; 123 result = ident_p4d_init(info, p4d, addr, next); 124 if (result) 125 return result; 126 if (pgtable_l5_enabled()) { 127 set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag)); 128 } else { 129 /* 130 * With p4d folded, pgd is equal to p4d. 131 * The pgd entry has to point to the pud page table in this case. 132 */ 133 pud_t *pud = pud_offset(p4d, 0); 134 set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag)); 135 } 136 } 137 138 return 0; 139 } 140