arch/x86/mm/ident_map.c

   1 /*
   2  * Helper routines for building identity mapping page tables. This is
   3  * included by both the compressed kernel and the regular kernel.
   4  */
   5
   6 static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
   7                            unsigned long addr, unsigned long end)
   8 {
   9         addr &= PMD_MASK;
  10         for (; addr < end; addr += PMD_SIZE) {
  11                 pmd_t *pmd = pmd_page + pmd_index(addr);
  12
  13                 if (pmd_present(*pmd))
  14                         continue;
  15
  16                 set_pmd(pmd, __pmd((addr - info->offset) | info->pmd_flag));
  17         }
  18 }
  19
  20 static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
  21                           unsigned long addr, unsigned long end)
  22 {
  23         unsigned long next;
  24
  25         for (; addr < end; addr = next) {
  26                 pud_t *pud = pud_page + pud_index(addr);
  27                 pmd_t *pmd;
  28
  29                 next = (addr & PUD_MASK) + PUD_SIZE;
  30                 if (next > end)
  31                         next = end;
  32
  33                 if (pud_present(*pud)) {
  34                         pmd = pmd_offset(pud, 0);
  35                         ident_pmd_init(info, pmd, addr, next);
  36                         continue;
  37                 }
  38                 pmd = (pmd_t *)info->alloc_pgt_page(info->context);
  39                 if (!pmd)
  40                         return -ENOMEM;
  41                 ident_pmd_init(info, pmd, addr, next);
  42                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
  43         }
  44
  45         return 0;
  46 }
  47
  48 int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
  49                               unsigned long pstart, unsigned long pend)
  50 {
  51         unsigned long addr = pstart + info->offset;
  52         unsigned long end = pend + info->offset;
  53         unsigned long next;
  54         int result;
  55
  56         for (; addr < end; addr = next) {
  57                 pgd_t *pgd = pgd_page + pgd_index(addr);
  58                 pud_t *pud;
  59
  60                 next = (addr & PGDIR_MASK) + PGDIR_SIZE;
  61                 if (next > end)
  62                         next = end;
  63
  64                 if (pgd_present(*pgd)) {
  65                         pud = pud_offset(pgd, 0);
  66                         result = ident_pud_init(info, pud, addr, next);
  67                         if (result)
  68                                 return result;
  69                         continue;
  70                 }
  71
  72                 pud = (pud_t *)info->alloc_pgt_page(info->context);
  73                 if (!pud)
  74                         return -ENOMEM;
  75                 result = ident_pud_init(info, pud, addr, next);
  76                 if (result)
  77                         return result;
  78                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
  79         }
  80
  81         return 0;
  82 }