diff options
Diffstat (limited to 'arch/x86/mm/ident_map.c')
-rw-r--r-- | arch/x86/mm/ident_map.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c new file mode 100644 index 0000000000..968d7005f4 --- /dev/null +++ b/arch/x86/mm/ident_map.c @@ -0,0 +1,147 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helper routines for building identity mapping page tables. This is + * included by both the compressed kernel and the regular kernel. + */ + +static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page, + unsigned long addr, unsigned long end) +{ + addr &= PMD_MASK; + for (; addr < end; addr += PMD_SIZE) { + pmd_t *pmd = pmd_page + pmd_index(addr); + + if (pmd_present(*pmd)) + continue; + + set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag)); + } +} + +static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, + unsigned long addr, unsigned long end) +{ + unsigned long next; + + for (; addr < end; addr = next) { + pud_t *pud = pud_page + pud_index(addr); + pmd_t *pmd; + + next = (addr & PUD_MASK) + PUD_SIZE; + if (next > end) + next = end; + + if (info->direct_gbpages) { + pud_t pudval; + + if (pud_present(*pud)) + continue; + + addr &= PUD_MASK; + pudval = __pud((addr - info->offset) | info->page_flag); + set_pud(pud, pudval); + continue; + } + + if (pud_present(*pud)) { + pmd = pmd_offset(pud, 0); + ident_pmd_init(info, pmd, addr, next); + continue; + } + pmd = (pmd_t *)info->alloc_pgt_page(info->context); + if (!pmd) + return -ENOMEM; + ident_pmd_init(info, pmd, addr, next); + set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); + } + + return 0; +} + +static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, + unsigned long addr, unsigned long end) +{ + unsigned long next; + int result; + + for (; addr < end; addr = next) { + p4d_t *p4d = p4d_page + p4d_index(addr); + pud_t *pud; + + next = (addr & P4D_MASK) + P4D_SIZE; + if (next > end) + next = end; + + if (p4d_present(*p4d)) { + pud = pud_offset(p4d, 0); + result = ident_pud_init(info, pud, addr, next); + if (result) + return result; + + continue; + } + pud = (pud_t *)info->alloc_pgt_page(info->context); + if (!pud) + return -ENOMEM; + + result = ident_pud_init(info, pud, addr, next); + if (result) + return result; + + set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); + } + + return 0; +} + +int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, + unsigned long pstart, unsigned long pend) +{ + unsigned long addr = pstart + info->offset; + unsigned long end = pend + info->offset; + unsigned long next; + int result; + + /* Set the default pagetable flags if not supplied */ + if (!info->kernpg_flag) + info->kernpg_flag = _KERNPG_TABLE; + + /* Filter out unsupported __PAGE_KERNEL_* bits: */ + info->kernpg_flag &= __default_kernel_pte_mask; + + for (; addr < end; addr = next) { + pgd_t *pgd = pgd_page + pgd_index(addr); + p4d_t *p4d; + + next = (addr & PGDIR_MASK) + PGDIR_SIZE; + if (next > end) + next = end; + + if (pgd_present(*pgd)) { + p4d = p4d_offset(pgd, 0); + result = ident_p4d_init(info, p4d, addr, next); + if (result) + return result; + continue; + } + + p4d = (p4d_t *)info->alloc_pgt_page(info->context); + if (!p4d) + return -ENOMEM; + result = ident_p4d_init(info, p4d, addr, next); + if (result) + return result; + if (pgtable_l5_enabled()) { + set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag)); + } else { + /* + * With p4d folded, pgd is equal to p4d. + * The pgd entry has to point to the pud page table in this case. + */ + pud_t *pud = pud_offset(p4d, 0); + set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag)); + } + } + + return 0; +} |