LXR linux/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
  12pgd_t *idmap_pgd;
  13
  14#ifdef CONFIG_ARM_LPAE
  15static 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 */
  39static 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
  52static 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
  64static 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
  85extern char  __idmap_text_start[], __idmap_text_end[];
  86
  87static 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}
 103early_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 */
 110void 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}
 125