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 #include <asm/system_info.h>
   9
  10 pgd_t *idmap_pgd;
  11
  12 #ifdef CONFIG_ARM_LPAE
  13 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  14         unsigned long prot)
  15 {
  16         pmd_t *pmd;
  17         unsigned long next;
  18
  19         if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  20                 pmd = pmd_alloc_one(&init_mm, addr);
  21                 if (!pmd) {
  22                         pr_warning("Failed to allocate identity pmd.\n");
  23                         return;
  24                 }
  25                 pud_populate(&init_mm, pud, pmd);
  26                 pmd += pmd_index(addr);
  27         } else
  28                 pmd = pmd_offset(pud, addr);
  29
  30         do {
  31                 next = pmd_addr_end(addr, end);
  32                 *pmd = __pmd((addr & PMD_MASK) | prot);
  33                 flush_pmd_entry(pmd);
  34         } while (pmd++, addr = next, addr != end);
  35 }
  36 #else   /* !CONFIG_ARM_LPAE */
  37 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  38         unsigned long prot)
  39 {
  40         pmd_t *pmd = pmd_offset(pud, addr);
  41
  42         addr = (addr & PMD_MASK) | prot;
  43         pmd[0] = __pmd(addr);
  44         addr += SECTION_SIZE;
  45         pmd[1] = __pmd(addr);
  46         flush_pmd_entry(pmd);
  47 }
  48 #endif  /* CONFIG_ARM_LPAE */
  49
  50 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  51         unsigned long prot)
  52 {
  53         pud_t *pud = pud_offset(pgd, addr);
  54         unsigned long next;
  55
  56         do {
  57                 next = pud_addr_end(addr, end);
  58                 idmap_add_pmd(pud, addr, next, prot);
  59         } while (pud++, addr = next, addr != end);
  60 }
  61
  62 static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
  63 {
  64         unsigned long prot, next;
  65
  66         prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  67         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  68                 prot |= PMD_BIT4;
  69
  70         pgd += pgd_index(addr);
  71         do {
  72                 next = pgd_addr_end(addr, end);
  73                 idmap_add_pud(pgd, addr, next, prot);
  74         } while (pgd++, addr = next, addr != end);
  75 }
  76
  77 extern char  __idmap_text_start[], __idmap_text_end[];
  78
  79 static int __init init_static_idmap(void)
  80 {
  81         phys_addr_t idmap_start, idmap_end;
  82
  83         idmap_pgd = pgd_alloc(&init_mm);
  84         if (!idmap_pgd)
  85                 return -ENOMEM;
  86
  87         /* Add an identity mapping for the physical address of the section. */
  88         idmap_start = virt_to_phys((void *)__idmap_text_start);
  89         idmap_end = virt_to_phys((void *)__idmap_text_end);
  90
  91         pr_info("Setting up static identity map for 0x%llx - 0x%llx\n",
  92                 (long long)idmap_start, (long long)idmap_end);
  93         identity_mapping_add(idmap_pgd, idmap_start, idmap_end);
  94
  95         /* Flush L1 for the hardware to see this page table content */
  96         flush_cache_louis();
  97
  98         return 0;
  99 }
 100 early_initcall(init_static_idmap);
 101
 102 /*
 103  * In order to soft-boot, we need to switch to a 1:1 mapping for the
 104  * cpu_reset functions. This will then ensure that we have predictable
 105  * results when turning off the mmu.
 106  */
 107 void setup_mm_for_reboot(void)
 108 {
 109         /* Switch to the identity mapping. */
 110         cpu_switch_mm(idmap_pgd, &init_mm);
 111
 112 #ifdef CONFIG_CPU_HAS_ASID
 113         /*
 114          * We don't have a clean ASID for the identity mapping, which
 115          * may clash with virtual addresses of the previous page tables
 116          * and therefore potentially in the TLB.
 117          */
 118         local_flush_tlb_all();
 119 #endif
 120 }