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
7static 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
21static 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
61static 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
89int 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