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                 /*
  28                  * Copy the original PMD to ensure that the PMD entries for
  29                  * the kernel image are preserved.
  30                  */
  31                 if (!pud_none(*pud))
  32                         memcpy(pmd, pmd_offset(pud, 0),
  33                                PTRS_PER_PMD * sizeof(pmd_t));
  34                 pud_populate(&init_mm, pud, pmd);
  35                 pmd += pmd_index(addr);
  36         } else
  37                 pmd = pmd_offset(pud, addr);
  38
  39         do {
  40                 next = pmd_addr_end(addr, end);
  41                 *pmd = __pmd((addr & PMD_MASK) | prot);
  42                 flush_pmd_entry(pmd);
  43         } while (pmd++, addr = next, addr != end);
  44 }
  45 #else   /* !CONFIG_ARM_LPAE */
  46 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  47         unsigned long prot)
  48 {
  49         pmd_t *pmd = pmd_offset(pud, addr);
  50
  51         addr = (addr & PMD_MASK) | prot;
  52         pmd[0] = __pmd(addr);
  53         addr += SECTION_SIZE;
  54         pmd[1] = __pmd(addr);
  55         flush_pmd_entry(pmd);
  56 }
  57 #endif  /* CONFIG_ARM_LPAE */
  58
  59 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  60         unsigned long prot)
  61 {
  62         pud_t *pud = pud_offset(pgd, addr);
  63         unsigned long next;
  64
  65         do {
  66                 next = pud_addr_end(addr, end);
  67                 idmap_add_pmd(pud, addr, next, prot);
  68         } while (pud++, addr = next, addr != end);
  69 }
  70
  71 static void identity_mapping_add(pgd_t *pgd, const char *text_start,
  72                                  const char *text_end, unsigned long prot)
  73 {
  74         unsigned long addr, end;
  75         unsigned long next;
  76
  77         addr = virt_to_phys(text_start);
  78         end = virt_to_phys(text_end);
  79
  80         prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  81
  82         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  83                 prot |= PMD_BIT4;
  84
  85         pgd += pgd_index(addr);
  86         do {
  87                 next = pgd_addr_end(addr, end);
  88                 idmap_add_pud(pgd, addr, next, prot);
  89         } while (pgd++, addr = next, addr != end);
  90 }
  91
  92 extern char  __idmap_text_start[], __idmap_text_end[];
  93
  94 static int __init init_static_idmap(void)
  95 {
  96         idmap_pgd = pgd_alloc(&init_mm);
  97         if (!idmap_pgd)
  98                 return -ENOMEM;
  99
 100         pr_info("Setting up static identity map for 0x%p - 0x%p\n",
 101                 __idmap_text_start, __idmap_text_end);
 102         identity_mapping_add(idmap_pgd, __idmap_text_start,
 103                              __idmap_text_end, 0);
 104
 105         /* Flush L1 for the hardware to see this page table content */
 106         flush_cache_louis();
 107
 108         return 0;
 109 }
 110 early_initcall(init_static_idmap);
 111
 112 /*
 113  * In order to soft-boot, we need to switch to a 1:1 mapping for the
 114  * cpu_reset functions. This will then ensure that we have predictable
 115  * results when turning off the mmu.
 116  */
 117 void setup_mm_for_reboot(void)
 118 {
 119         /* Switch to the identity mapping. */
 120         cpu_switch_mm(idmap_pgd, &init_mm);
 121         local_flush_bp_all();
 122
 123 #ifdef CONFIG_CPU_HAS_ASID
 124         /*
 125          * We don't have a clean ASID for the identity mapping, which
 126          * may clash with virtual addresses of the previous page tables
 127          * and therefore potentially in the TLB.
 128          */
 129         local_flush_tlb_all();
 130 #endif
 131 }