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(pgd_t *pgd, unsigned long addr, unsigned long end,
   8         unsigned long prot)
   9 {
  10         pmd_t *pmd = pmd_offset(pgd, 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 void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
  20 {
  21         unsigned long prot, next;
  22
  23         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE;
  24         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  25                 prot |= PMD_BIT4;
  26
  27         pgd += pgd_index(addr);
  28         do {
  29                 next = pgd_addr_end(addr, end);
  30                 idmap_add_pmd(pgd, addr, next, prot);
  31         } while (pgd++, addr = next, addr != end);
  32 }
  33
  34 #ifdef CONFIG_SMP
  35 static void idmap_del_pmd(pgd_t *pgd, unsigned long addr, unsigned long end)
  36 {
  37         pmd_t *pmd = pmd_offset(pgd, addr);
  38         pmd_clear(pmd);
  39 }
  40
  41 void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
  42 {
  43         unsigned long next;
  44
  45         pgd += pgd_index(addr);
  46         do {
  47                 next = pgd_addr_end(addr, end);
  48                 idmap_del_pmd(pgd, addr, next);
  49         } while (pgd++, addr = next, addr != end);
  50 }
  51 #endif
  52
  53 /*
  54  * In order to soft-boot, we need to insert a 1:1 mapping in place of
  55  * the user-mode pages.  This will then ensure that we have predictable
  56  * results when turning the mmu off
  57  */
  58 void setup_mm_for_reboot(char mode)
  59 {
  60         /*
  61          * We need to access to user-mode page tables here. For kernel threads
  62          * we don't have any user-mode mappings so we use the context that we
  63          * "borrowed".
  64          */
  65         identity_mapping_add(current->active_mm->pgd, 0, TASK_SIZE);
  66         local_flush_tlb_all();
  67 }