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
  12/*
  13 * Note: accesses outside of the kernel image and the identity map area
  14 * are not supported on any CPU using the idmap tables as its current
  15 * page tables.
  16 */
  17pgd_t *idmap_pgd;
  18phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
  19
  20#ifdef CONFIG_ARM_LPAE
  21static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  22        unsigned long prot)
  23{
  24        pmd_t *pmd;
  25        unsigned long next;
  26
  27        if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
  28                pmd = pmd_alloc_one(&init_mm, addr);
  29                if (!pmd) {
  30                        pr_warn("Failed to allocate identity pmd.\n");
  31                        return;
  32                }
  33                /*
  34                 * Copy the original PMD to ensure that the PMD entries for
  35                 * the kernel image are preserved.
  36                 */
  37                if (!pud_none(*pud))
  38                        memcpy(pmd, pmd_offset(pud, 0),
  39                               PTRS_PER_PMD * sizeof(pmd_t));
  40                pud_populate(&init_mm, pud, pmd);
  41                pmd += pmd_index(addr);
  42        } else
  43                pmd = pmd_offset(pud, addr);
  44
  45        do {
  46                next = pmd_addr_end(addr, end);
  47                *pmd = __pmd((addr & PMD_MASK) | prot);
  48                flush_pmd_entry(pmd);
  49        } while (pmd++, addr = next, addr != end);
  50}
  51#else   /* !CONFIG_ARM_LPAE */
  52static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
  53        unsigned long prot)
  54{
  55        pmd_t *pmd = pmd_offset(pud, addr);
  56
  57        addr = (addr & PMD_MASK) | prot;
  58        pmd[0] = __pmd(addr);
  59        addr += SECTION_SIZE;
  60        pmd[1] = __pmd(addr);
  61        flush_pmd_entry(pmd);
  62}
  63#endif  /* CONFIG_ARM_LPAE */
  64
  65static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
  66        unsigned long prot)
  67{
  68        pud_t *pud = pud_offset(pgd, addr);
  69        unsigned long next;
  70
  71        do {
  72                next = pud_addr_end(addr, end);
  73                idmap_add_pmd(pud, addr, next, prot);
  74        } while (pud++, addr = next, addr != end);
  75}
  76
  77static void identity_mapping_add(pgd_t *pgd, const char *text_start,
  78                                 const char *text_end, unsigned long prot)
  79{
  80        unsigned long addr, end;
  81        unsigned long next;
  82
  83        addr = virt_to_idmap(text_start);
  84        end = virt_to_idmap(text_end);
  85        pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
  86
  87        prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
  88
  89        if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
  90                prot |= PMD_BIT4;
  91
  92        pgd += pgd_index(addr);
  93        do {
  94                next = pgd_addr_end(addr, end);
  95                idmap_add_pud(pgd, addr, next, prot);
  96        } while (pgd++, addr = next, addr != end);
  97}
  98
  99extern char  __idmap_text_start[], __idmap_text_end[];
 100
 101static int __init init_static_idmap(void)
 102{
 103        idmap_pgd = pgd_alloc(&init_mm);
 104        if (!idmap_pgd)
 105                return -ENOMEM;
 106
 107        identity_mapping_add(idmap_pgd, __idmap_text_start,
 108                             __idmap_text_end, 0);
 109
 110        /* Flush L1 for the hardware to see this page table content */
 111        flush_cache_louis();
 112
 113        return 0;
 114}
 115early_initcall(init_static_idmap);
 116
 117/*
 118 * In order to soft-boot, we need to switch to a 1:1 mapping for the
 119 * cpu_reset functions. This will then ensure that we have predictable
 120 * results when turning off the mmu.
 121 */
 122void setup_mm_for_reboot(void)
 123{
 124        /* Switch to the identity mapping. */
 125        cpu_switch_mm(idmap_pgd, &init_mm);
 126        local_flush_bp_all();
 127
 128#ifdef CONFIG_CPU_HAS_ASID
 129        /*
 130         * We don't have a clean ASID for the identity mapping, which
 131         * may clash with virtual addresses of the previous page tables
 132         * and therefore potentially in the TLB.
 133         */
 134        local_flush_tlb_all();
 135#endif
 136}
 137