arch/arm/mm/idmap.c

   1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   2
   3 #include <linux/kernel.h>
   4
   5 #include <asm/cputype.h>
   6 #include <asm/pgalloc.h>
   7 #include <asm/pgtable.h>
   8
   9 #ifdef CONFIG_ARM_LPAE
  10 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  11         unsigned long prot)
  12 {
  13         pmd_t *pmd;
  14         unsigned long next;
  15
  16         if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  17                 pmd = pmd_alloc_one(NULL, addr);
  18                 if (!pmd) {
  19                         pr_warning("Failed to allocate identity pmd.\n");
  20                         return;
  21                 }
  22                 pud_populate(NULL, pud, pmd);
  23                 pmd += pmd_index(addr);
  24         } else
  25                 pmd = pmd_offset(pud, addr);
  26
  27         do {
  28                 next = pmd_addr_end(addr, end);
  29                 *pmd = __pmd((addr & PMD_MASK) | prot);
  30                 flush_pmd_entry(pmd);
  31         } while (pmd++, addr = next, addr != end);
  32 }
  33 #else   /* !CONFIG_ARM_LPAE */
  34 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  35         unsigned long prot)
  36 {
  37         pmd_t *pmd = pmd_offset(pud, addr);
  38
  39         addr = (addr & PMD_MASK) | prot;
  40         pmd[0] = __pmd(addr);
  41         addr += SECTION_SIZE;
  42         pmd[1] = __pmd(addr);
  43         flush_pmd_entry(pmd);
  44 }
  45 #endif  /* CONFIG_ARM_LPAE */
  46
  47 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  48         unsigned long prot)
  49 {
  50         pud_t *pud = pud_offset(pgd, addr);
  51         unsigned long next;
  52
  53         do {
  54                 next = pud_addr_end(addr, end);
  55                 idmap_add_pmd(pud, addr, next, prot);
  56         } while (pud++, addr = next, addr != end);
  57 }
  58
  59 void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
  60 {
  61         unsigned long prot, next;
  62
  63         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  64         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  65                 prot |= PMD_BIT4;
  66
  67         pgd += pgd_index(addr);
  68         do {
  69                 next = pgd_addr_end(addr, end);
  70                 idmap_add_pud(pgd, addr, next, prot);
  71         } while (pgd++, addr = next, addr != end);
  72 }
  73
  74 #ifdef CONFIG_SMP
  75 static void idmap_del_pmd(pud_t *pud, unsigned long addr, unsigned long end)
  76 {
  77         pmd_t *pmd;
  78
  79         if (pud_none_or_clear_bad(pud))
  80                 return;
  81         pmd = pmd_offset(pud, addr);
  82         pmd_clear(pmd);
  83 }
  84
  85 static void idmap_del_pud(pgd_t *pgd, unsigned long addr, unsigned long end)
  86 {
  87         pud_t *pud = pud_offset(pgd, addr);
  88         unsigned long next;
  89
  90         do {
  91                 next = pud_addr_end(addr, end);
  92                 idmap_del_pmd(pud, addr, next);
  93         } while (pud++, addr = next, addr != end);
  94 }
  95
  96 void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
  97 {
  98         unsigned long next;
  99
 100         pgd += pgd_index(addr);
 101         do {
 102                 next = pgd_addr_end(addr, end);
 103                 idmap_del_pud(pgd, addr, next);
 104         } while (pgd++, addr = next, addr != end);
 105 }
 106 #endif
 107
 108 /*
 109  * In order to soft-boot, we need to insert a 1:1 mapping in place of
 110  * the user-mode pages.  This will then ensure that we have predictable
 111  * results when turning the mmu off
 112  */
 113 void setup_mm_for_reboot(char mode)
 114 {
 115         /*
 116          * We need to access to user-mode page tables here. For kernel threads
 117          * we don't have any user-mode mappings so we use the context that we
 118          * "borrowed".
 119          */
 120         identity_mapping_add(current->active_mm->pgd, 0, TASK_SIZE);
 121         local_flush_tlb_all();
 122 }