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->page_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 (info->direct_gbpages) {
  34                         pud_t pudval;
  35
  36                         if (pud_present(*pud))
  37                                 continue;
  38
  39                         addr &= PUD_MASK;
  40                         pudval = __pud((addr - info->offset) | info->page_flag);
  41                         set_pud(pud, pudval);
  42                         continue;
  43                 }
  44
  45                 if (pud_present(*pud)) {
  46                         pmd = pmd_offset(pud, 0);
  47                         ident_pmd_init(info, pmd, addr, next);
  48                         continue;
  49                 }
  50                 pmd = (pmd_t *)info->alloc_pgt_page(info->context);
  51                 if (!pmd)
  52                         return -ENOMEM;
  53                 ident_pmd_init(info, pmd, addr, next);
  54                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
  55         }
  56
  57         return 0;
  58 }
  59
  60 static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
  61                           unsigned long addr, unsigned long end)
  62 {
  63         unsigned long next;
  64
  65         for (; addr < end; addr = next) {
  66                 p4d_t *p4d = p4d_page + p4d_index(addr);
  67                 pud_t *pud;
  68
  69                 next = (addr & P4D_MASK) + P4D_SIZE;
  70                 if (next > end)
  71                         next = end;
  72
  73                 if (p4d_present(*p4d)) {
  74                         pud = pud_offset(p4d, 0);
  75                         ident_pud_init(info, pud, addr, next);
  76                         continue;
  77                 }
  78                 pud = (pud_t *)info->alloc_pgt_page(info->context);
  79                 if (!pud)
  80                         return -ENOMEM;
  81                 ident_pud_init(info, pud, addr, next);
  82                 set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
  83         }
  84
  85         return 0;
  86 }
  87
  88 int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
  89                               unsigned long pstart, unsigned long pend)
  90 {
  91         unsigned long addr = pstart + info->offset;
  92         unsigned long end = pend + info->offset;
  93         unsigned long next;
  94         int result;
  95
  96         for (; addr < end; addr = next) {
  97                 pgd_t *pgd = pgd_page + pgd_index(addr);
  98                 p4d_t *p4d;
  99
 100                 next = (addr & PGDIR_MASK) + PGDIR_SIZE;
 101                 if (next > end)
 102                         next = end;
 103
 104                 if (pgd_present(*pgd)) {
 105                         p4d = p4d_offset(pgd, 0);
 106                         result = ident_p4d_init(info, p4d, addr, next);
 107                         if (result)
 108                                 return result;
 109                         continue;
 110                 }
 111
 112                 p4d = (p4d_t *)info->alloc_pgt_page(info->context);
 113                 if (!p4d)
 114                         return -ENOMEM;
 115                 result = ident_p4d_init(info, p4d, addr, next);
 116                 if (result)
 117                         return result;
 118                 if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
 119                         set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
 120                 } else {
 121                         /*
 122                          * With p4d folded, pgd is equal to p4d.
 123                          * The pgd entry has to point to the pud page table in this case.
 124                          */
 125                         pud_t *pud = pud_offset(p4d, 0);
 126                         set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
 127                 }
 128         }
 129
 130         return 0;
 131 }