arch/arm/mm/idmap.c

   1 #include <linux/kernel.h>
   2
   3 #include <asm/cputype.h>
   4 #include <asm/pgalloc.h>
   5 #include <asm/pgtable.h>
   6
   7 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
   8         unsigned long prot)
   9 {
  10         pmd_t *pmd = pmd_offset(pud, addr);
  11
  12         addr = (addr & PMD_MASK) | prot;
  13         pmd[0] = __pmd(addr);
  14         addr += SECTION_SIZE;
  15         pmd[1] = __pmd(addr);
  16         flush_pmd_entry(pmd);
  17 }
  18
  19 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  20         unsigned long prot)
  21 {
  22         pud_t *pud = pud_offset(pgd, addr);
  23         unsigned long next;
  24
  25         do {
  26                 next = pud_addr_end(addr, end);
  27                 idmap_add_pmd(pud, addr, next, prot);
  28         } while (pud++, addr = next, addr != end);
  29 }
  30
  31 void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
  32 {
  33         unsigned long prot, next;
  34
  35         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE;
  36         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  37                 prot |= PMD_BIT4;
  38
  39         pgd += pgd_index(addr);
  40         do {
  41                 next = pgd_addr_end(addr, end);
  42                 idmap_add_pud(pgd, addr, next, prot);
  43         } while (pgd++, addr = next, addr != end);
  44 }
  45
  46 #ifdef CONFIG_SMP
  47 static void idmap_del_pmd(pud_t *pud, unsigned long addr, unsigned long end)
  48 {
  49         pmd_t *pmd = pmd_offset(pud, addr);
  50         pmd_clear(pmd);
  51 }
  52
  53 static void idmap_del_pud(pgd_t *pgd, unsigned long addr, unsigned long end)
  54 {
  55         pud_t *pud = pud_offset(pgd, addr);
  56         unsigned long next;
  57
  58         do {
  59                 next = pud_addr_end(addr, end);
  60                 idmap_del_pmd(pud, addr, next);
  61         } while (pud++, addr = next, addr != end);
  62 }
  63
  64 void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
  65 {
  66         unsigned long next;
  67
  68         pgd += pgd_index(addr);
  69         do {
  70                 next = pgd_addr_end(addr, end);
  71                 idmap_del_pud(pgd, addr, next);
  72         } while (pgd++, addr = next, addr != end);
  73 }
  74 #endif
  75
  76 /*
  77  * In order to soft-boot, we need to insert a 1:1 mapping in place of
  78  * the user-mode pages.  This will then ensure that we have predictable
  79  * results when turning the mmu off
  80  */
  81 void setup_mm_for_reboot(char mode)
  82 {
  83         /*
  84          * We need to access to user-mode page tables here. For kernel threads
  85          * we don't have any user-mode mappings so we use the context that we
  86          * "borrowed".
  87          */
  88         identity_mapping_add(current->active_mm->pgd, 0, TASK_SIZE);
  89         local_flush_tlb_all();
  90 }