arch/arm/mm/idmap.c

   1 #include <linux/module.h>
   2 #include <linux/kernel.h>
   3 #include <linux/slab.h>
   4
   5 #include <asm/cputype.h>
   6 #include <asm/idmap.h>
   7 #include <asm/pgalloc.h>
   8 #include <asm/pgtable.h>
   9 #include <asm/sections.h>
  10 #include <asm/system_info.h>
  11
  12 pgd_t *idmap_pgd;
  13
  14 #ifdef CONFIG_ARM_LPAE
  15 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  16         unsigned long prot)
  17 {
  18         pmd_t *pmd;
  19         unsigned long next;
  20
  21         if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  22                 pmd = pmd_alloc_one(&init_mm, addr);
  23                 if (!pmd) {
  24                         pr_warning("Failed to allocate identity pmd.\n");
  25                         return;
  26                 }
  27                 pud_populate(&init_mm, pud, pmd);
  28                 pmd += pmd_index(addr);
  29         } else
  30                 pmd = pmd_offset(pud, addr);
  31
  32         do {
  33                 next = pmd_addr_end(addr, end);
  34                 *pmd = __pmd((addr & PMD_MASK) | prot);
  35                 flush_pmd_entry(pmd);
  36         } while (pmd++, addr = next, addr != end);
  37 }
  38 #else   /* !CONFIG_ARM_LPAE */
  39 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  40         unsigned long prot)
  41 {
  42         pmd_t *pmd = pmd_offset(pud, addr);
  43
  44         addr = (addr & PMD_MASK) | prot;
  45         pmd[0] = __pmd(addr);
  46         addr += SECTION_SIZE;
  47         pmd[1] = __pmd(addr);
  48         flush_pmd_entry(pmd);
  49 }
  50 #endif  /* CONFIG_ARM_LPAE */
  51
  52 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  53         unsigned long prot)
  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_add_pmd(pud, addr, next, prot);
  61         } while (pud++, addr = next, addr != end);
  62 }
  63
  64 static void identity_mapping_add(pgd_t *pgd, const char *text_start,
  65                                  const char *text_end, unsigned long prot)
  66 {
  67         unsigned long addr, end;
  68         unsigned long next;
  69
  70         addr = virt_to_phys(text_start);
  71         end = virt_to_phys(text_end);
  72
  73         prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  74
  75         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  76                 prot |= PMD_BIT4;
  77
  78         pgd += pgd_index(addr);
  79         do {
  80                 next = pgd_addr_end(addr, end);
  81                 idmap_add_pud(pgd, addr, next, prot);
  82         } while (pgd++, addr = next, addr != end);
  83 }
  84
  85 extern char  __idmap_text_start[], __idmap_text_end[];
  86
  87 static int __init init_static_idmap(void)
  88 {
  89         idmap_pgd = pgd_alloc(&init_mm);
  90         if (!idmap_pgd)
  91                 return -ENOMEM;
  92
  93         pr_info("Setting up static identity map for 0x%p - 0x%p\n",
  94                 __idmap_text_start, __idmap_text_end);
  95         identity_mapping_add(idmap_pgd, __idmap_text_start,
  96                              __idmap_text_end, 0);
  97
  98         /* Flush L1 for the hardware to see this page table content */
  99         flush_cache_louis();
 100
 101         return 0;
 102 }
 103 early_initcall(init_static_idmap);
 104
 105 /*
 106  * In order to soft-boot, we need to switch to a 1:1 mapping for the
 107  * cpu_reset functions. This will then ensure that we have predictable
 108  * results when turning off the mmu.
 109  */
 110 void setup_mm_for_reboot(void)
 111 {
 112         /* Switch to the identity mapping. */
 113         cpu_switch_mm(idmap_pgd, &init_mm);
 114         local_flush_bp_all();
 115
 116 #ifdef CONFIG_CPU_HAS_ASID
 117         /*
 118          * We don't have a clean ASID for the identity mapping, which
 119          * may clash with virtual addresses of the previous page tables
 120          * and therefore potentially in the TLB.
 121          */
 122         local_flush_tlb_all();
 123 #endif
 124 }