arch/arm/mm/idmap.c

   1 #include <linux/kernel.h>
   2
   3 #include <asm/cputype.h>
   4 #include <asm/idmap.h>
   5 #include <asm/pgalloc.h>
   6 #include <asm/pgtable.h>
   7 #include <asm/sections.h>
   8
   9 pgd_t *idmap_pgd;
  10
  11 #ifdef CONFIG_ARM_LPAE
  12 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  13         unsigned long prot)
  14 {
  15         pmd_t *pmd;
  16         unsigned long next;
  17
  18         if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  19                 pmd = pmd_alloc_one(&init_mm, addr);
  20                 if (!pmd) {
  21                         pr_warning("Failed to allocate identity pmd.\n");
  22                         return;
  23                 }
  24                 pud_populate(&init_mm, pud, pmd);
  25                 pmd += pmd_index(addr);
  26         } else
  27                 pmd = pmd_offset(pud, addr);
  28
  29         do {
  30                 next = pmd_addr_end(addr, end);
  31                 *pmd = __pmd((addr & PMD_MASK) | prot);
  32                 flush_pmd_entry(pmd);
  33         } while (pmd++, addr = next, addr != end);
  34 }
  35 #else   /* !CONFIG_ARM_LPAE */
  36 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  37         unsigned long prot)
  38 {
  39         pmd_t *pmd = pmd_offset(pud, addr);
  40
  41         addr = (addr & PMD_MASK) | prot;
  42         pmd[0] = __pmd(addr);
  43         addr += SECTION_SIZE;
  44         pmd[1] = __pmd(addr);
  45         flush_pmd_entry(pmd);
  46 }
  47 #endif  /* CONFIG_ARM_LPAE */
  48
  49 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  50         unsigned long prot)
  51 {
  52         pud_t *pud = pud_offset(pgd, addr);
  53         unsigned long next;
  54
  55         do {
  56                 next = pud_addr_end(addr, end);
  57                 idmap_add_pmd(pud, addr, next, prot);
  58         } while (pud++, addr = next, addr != end);
  59 }
  60
  61 static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
  62 {
  63         unsigned long prot, next;
  64
  65         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  66         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  67                 prot |= PMD_BIT4;
  68
  69         pgd += pgd_index(addr);
  70         do {
  71                 next = pgd_addr_end(addr, end);
  72                 idmap_add_pud(pgd, addr, next, prot);
  73         } while (pgd++, addr = next, addr != end);
  74 }
  75
  76 extern char  __idmap_text_start[], __idmap_text_end[];
  77
  78 static int __init init_static_idmap(void)
  79 {
  80         phys_addr_t idmap_start, idmap_end;
  81
  82         idmap_pgd = pgd_alloc(&init_mm);
  83         if (!idmap_pgd)
  84                 return -ENOMEM;
  85
  86         /* Add an identity mapping for the physical address of the section. */
  87         idmap_start = virt_to_phys((void *)__idmap_text_start);
  88         idmap_end = virt_to_phys((void *)__idmap_text_end);
  89
  90         pr_info("Setting up static identity map for 0x%llx - 0x%llx\n",
  91                 (long long)idmap_start, (long long)idmap_end);
  92         identity_mapping_add(idmap_pgd, idmap_start, idmap_end);
  93
  94         return 0;
  95 }
  96 early_initcall(init_static_idmap);
  97
  98 /*
  99  * In order to soft-boot, we need to switch to a 1:1 mapping for the
 100  * cpu_reset functions. This will then ensure that we have predictable
 101  * results when turning off the mmu.
 102  */
 103 void setup_mm_for_reboot(void)
 104 {
 105         /* Clean and invalidate L1. */
 106         flush_cache_all();
 107
 108         /* Switch to the identity mapping. */
 109         cpu_switch_mm(idmap_pgd, &init_mm);
 110
 111         /* Flush the TLB. */
 112         local_flush_tlb_all();
 113 }