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 phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
  14
  15 #ifdef CONFIG_ARM_LPAE
  16 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  17         unsigned long prot)
  18 {
  19         pmd_t *pmd;
  20         unsigned long next;
  21
  22         if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  23                 pmd = pmd_alloc_one(&init_mm, addr);
  24                 if (!pmd) {
  25                         pr_warning("Failed to allocate identity pmd.\n");
  26                         return;
  27                 }
  28                 /*
  29                  * Copy the original PMD to ensure that the PMD entries for
  30                  * the kernel image are preserved.
  31                  */
  32                 if (!pud_none(*pud))
  33                         memcpy(pmd, pmd_offset(pud, 0),
  34                                PTRS_PER_PMD * sizeof(pmd_t));
  35                 pud_populate(&init_mm, pud, pmd);
  36                 pmd += pmd_index(addr);
  37         } else
  38                 pmd = pmd_offset(pud, addr);
  39
  40         do {
  41                 next = pmd_addr_end(addr, end);
  42                 *pmd = __pmd((addr & PMD_MASK) | prot);
  43                 flush_pmd_entry(pmd);
  44         } while (pmd++, addr = next, addr != end);
  45 }
  46 #else   /* !CONFIG_ARM_LPAE */
  47 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  48         unsigned long prot)
  49 {
  50         pmd_t *pmd = pmd_offset(pud, addr);
  51
  52         addr = (addr & PMD_MASK) | prot;
  53         pmd[0] = __pmd(addr);
  54         addr += SECTION_SIZE;
  55         pmd[1] = __pmd(addr);
  56         flush_pmd_entry(pmd);
  57 }
  58 #endif  /* CONFIG_ARM_LPAE */
  59
  60 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  61         unsigned long prot)
  62 {
  63         pud_t *pud = pud_offset(pgd, addr);
  64         unsigned long next;
  65
  66         do {
  67                 next = pud_addr_end(addr, end);
  68                 idmap_add_pmd(pud, addr, next, prot);
  69         } while (pud++, addr = next, addr != end);
  70 }
  71
  72 static void identity_mapping_add(pgd_t *pgd, const char *text_start,
  73                                  const char *text_end, unsigned long prot)
  74 {
  75         unsigned long addr, end;
  76         unsigned long next;
  77
  78         addr = virt_to_idmap(text_start);
  79         end = virt_to_idmap(text_end);
  80
  81         prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  82
  83         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  84                 prot |= PMD_BIT4;
  85
  86         pgd += pgd_index(addr);
  87         do {
  88                 next = pgd_addr_end(addr, end);
  89                 idmap_add_pud(pgd, addr, next, prot);
  90         } while (pgd++, addr = next, addr != end);
  91 }
  92
  93 extern char  __idmap_text_start[], __idmap_text_end[];
  94
  95 static int __init init_static_idmap(void)
  96 {
  97         idmap_pgd = pgd_alloc(&init_mm);
  98         if (!idmap_pgd)
  99                 return -ENOMEM;
 100
 101         pr_info("Setting up static identity map for 0x%p - 0x%p\n",
 102                 __idmap_text_start, __idmap_text_end);
 103         identity_mapping_add(idmap_pgd, __idmap_text_start,
 104                              __idmap_text_end, 0);
 105
 106         /* Flush L1 for the hardware to see this page table content */
 107         flush_cache_louis();
 108
 109         return 0;
 110 }
 111 early_initcall(init_static_idmap);
 112
 113 /*
 114  * In order to soft-boot, we need to switch to a 1:1 mapping for the
 115  * cpu_reset functions. This will then ensure that we have predictable
 116  * results when turning off the mmu.
 117  */
 118 void setup_mm_for_reboot(void)
 119 {
 120         /* Switch to the identity mapping. */
 121         cpu_switch_mm(idmap_pgd, &init_mm);
 122         local_flush_bp_all();
 123
 124 #ifdef CONFIG_CPU_HAS_ASID
 125         /*
 126          * We don't have a clean ASID for the identity mapping, which
 127          * may clash with virtual addresses of the previous page tables
 128          * and therefore potentially in the TLB.
 129          */
 130         local_flush_tlb_all();
 131 #endif
 132 }