LXR linux/arch/x86/realmode/init.c

   1#include <linux/io.h>
   2#include <linux/slab.h>
   3#include <linux/memblock.h>
   4
   5#include <asm/cacheflush.h>
   6#include <asm/pgtable.h>
   7#include <asm/realmode.h>
   8#include <asm/tlbflush.h>
   9
  10struct real_mode_header *real_mode_header;
  11u32 *trampoline_cr4_features;
  12
  13/* Hold the pgd entry used on booting additional CPUs */
  14pgd_t trampoline_pgd_entry;
  15
  16void __init set_real_mode_mem(phys_addr_t mem, size_t size)
  17{
  18        void *base = __va(mem);
  19
  20        real_mode_header = (struct real_mode_header *) base;
  21        printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  22               base, (unsigned long long)mem, size);
  23}
  24
  25void __init reserve_real_mode(void)
  26{
  27        phys_addr_t mem;
  28        size_t size = real_mode_size_needed();
  29
  30        if (!size)
  31                return;
  32
  33        WARN_ON(slab_is_available());
  34
  35        /* Has to be under 1M so we can execute real-mode AP code. */
  36        mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  37        if (!mem) {
  38                pr_info("No sub-1M memory is available for the trampoline\n");
  39                return;
  40        }
  41
  42        memblock_reserve(mem, size);
  43        set_real_mode_mem(mem, size);
  44}
  45
  46static void __init setup_real_mode(void)
  47{
  48        u16 real_mode_seg;
  49        const u32 *rel;
  50        u32 count;
  51        unsigned char *base;
  52        unsigned long phys_base;
  53        struct trampoline_header *trampoline_header;
  54        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  55#ifdef CONFIG_X86_64
  56        u64 *trampoline_pgd;
  57        u64 efer;
  58#endif
  59
  60        base = (unsigned char *)real_mode_header;
  61
  62        memcpy(base, real_mode_blob, size);
  63
  64        phys_base = __pa(base);
  65        real_mode_seg = phys_base >> 4;
  66
  67        rel = (u32 *) real_mode_relocs;
  68
  69        /* 16-bit segment relocations. */
  70        count = *rel++;
  71        while (count--) {
  72                u16 *seg = (u16 *) (base + *rel++);
  73                *seg = real_mode_seg;
  74        }
  75
  76        /* 32-bit linear relocations. */
  77        count = *rel++;
  78        while (count--) {
  79                u32 *ptr = (u32 *) (base + *rel++);
  80                *ptr += phys_base;
  81        }
  82
  83        /* Must be perfomed *after* relocation. */
  84        trampoline_header = (struct trampoline_header *)
  85                __va(real_mode_header->trampoline_header);
  86
  87#ifdef CONFIG_X86_32
  88        trampoline_header->start = __pa_symbol(startup_32_smp);
  89        trampoline_header->gdt_limit = __BOOT_DS + 7;
  90        trampoline_header->gdt_base = __pa_symbol(boot_gdt);
  91#else
  92        /*
  93         * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
  94         * so we need to mask it out.
  95         */
  96        rdmsrl(MSR_EFER, efer);
  97        trampoline_header->efer = efer & ~EFER_LMA;
  98
  99        trampoline_header->start = (u64) secondary_startup_64;
 100        trampoline_cr4_features = &trampoline_header->cr4;
 101        *trampoline_cr4_features = mmu_cr4_features;
 102
 103        trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
 104        trampoline_pgd[0] = trampoline_pgd_entry.pgd;
 105        trampoline_pgd[511] = init_level4_pgt[511].pgd;
 106#endif
 107}
 108
 109/*
 110 * reserve_real_mode() gets called very early, to guarantee the
 111 * availability of low memory. This is before the proper kernel page
 112 * tables are set up, so we cannot set page permissions in that
 113 * function. Also trampoline code will be executed by APs so we
 114 * need to mark it executable at do_pre_smp_initcalls() at least,
 115 * thus run it as a early_initcall().
 116 */
 117static void __init set_real_mode_permissions(void)
 118{
 119        unsigned char *base = (unsigned char *) real_mode_header;
 120        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 121
 122        size_t ro_size =
 123                PAGE_ALIGN(real_mode_header->ro_end) -
 124                __pa(base);
 125
 126        size_t text_size =
 127                PAGE_ALIGN(real_mode_header->ro_end) -
 128                real_mode_header->text_start;
 129
 130        unsigned long text_start =
 131                (unsigned long) __va(real_mode_header->text_start);
 132
 133        set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 134        set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 135        set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 136}
 137
 138static int __init init_real_mode(void)
 139{
 140        if (!real_mode_header)
 141                panic("Real mode trampoline was not allocated");
 142
 143        setup_real_mode();
 144        set_real_mode_permissions();
 145
 146        return 0;
 147}
 148early_initcall(init_real_mode);
 149