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

   1#include <linux/io.h>
   2#include <linux/memblock.h>
   3
   4#include <asm/cacheflush.h>
   5#include <asm/pgtable.h>
   6#include <asm/realmode.h>
   7
   8struct real_mode_header *real_mode_header;
   9u32 *trampoline_cr4_features;
  10
  11void __init reserve_real_mode(void)
  12{
  13        phys_addr_t mem;
  14        unsigned char *base;
  15        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  16
  17        /* Has to be under 1M so we can execute real-mode AP code. */
  18        mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  19        if (!mem)
  20                panic("Cannot allocate trampoline\n");
  21
  22        base = __va(mem);
  23        memblock_reserve(mem, size);
  24        real_mode_header = (struct real_mode_header *) base;
  25        printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  26               base, (unsigned long long)mem, size);
  27}
  28
  29void __init setup_real_mode(void)
  30{
  31        u16 real_mode_seg;
  32        const u32 *rel;
  33        u32 count;
  34        unsigned char *base;
  35        unsigned long phys_base;
  36        struct trampoline_header *trampoline_header;
  37        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  38#ifdef CONFIG_X86_64
  39        u64 *trampoline_pgd;
  40        u64 efer;
  41#endif
  42
  43        base = (unsigned char *)real_mode_header;
  44
  45        memcpy(base, real_mode_blob, size);
  46
  47        phys_base = __pa(base);
  48        real_mode_seg = phys_base >> 4;
  49
  50        rel = (u32 *) real_mode_relocs;
  51
  52        /* 16-bit segment relocations. */
  53        count = *rel++;
  54        while (count--) {
  55                u16 *seg = (u16 *) (base + *rel++);
  56                *seg = real_mode_seg;
  57        }
  58
  59        /* 32-bit linear relocations. */
  60        count = *rel++;
  61        while (count--) {
  62                u32 *ptr = (u32 *) (base + *rel++);
  63                *ptr += phys_base;
  64        }
  65
  66        /* Must be perfomed *after* relocation. */
  67        trampoline_header = (struct trampoline_header *)
  68                __va(real_mode_header->trampoline_header);
  69
  70#ifdef CONFIG_X86_32
  71        trampoline_header->start = __pa_symbol(startup_32_smp);
  72        trampoline_header->gdt_limit = __BOOT_DS + 7;
  73        trampoline_header->gdt_base = __pa_symbol(boot_gdt);
  74#else
  75        /*
  76         * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
  77         * so we need to mask it out.
  78         */
  79        rdmsrl(MSR_EFER, efer);
  80        trampoline_header->efer = efer & ~EFER_LMA;
  81
  82        trampoline_header->start = (u64) secondary_startup_64;
  83        trampoline_cr4_features = &trampoline_header->cr4;
  84        *trampoline_cr4_features = __read_cr4();
  85
  86        trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
  87        trampoline_pgd[0] = init_level4_pgt[pgd_index(__PAGE_OFFSET)].pgd;
  88        trampoline_pgd[511] = init_level4_pgt[511].pgd;
  89#endif
  90}
  91
  92/*
  93 * reserve_real_mode() gets called very early, to guarantee the
  94 * availability of low memory. This is before the proper kernel page
  95 * tables are set up, so we cannot set page permissions in that
  96 * function. Also trampoline code will be executed by APs so we
  97 * need to mark it executable at do_pre_smp_initcalls() at least,
  98 * thus run it as a early_initcall().
  99 */
 100static int __init set_real_mode_permissions(void)
 101{
 102        unsigned char *base = (unsigned char *) real_mode_header;
 103        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 104
 105        size_t ro_size =
 106                PAGE_ALIGN(real_mode_header->ro_end) -
 107                __pa(base);
 108
 109        size_t text_size =
 110                PAGE_ALIGN(real_mode_header->ro_end) -
 111                real_mode_header->text_start;
 112
 113        unsigned long text_start =
 114                (unsigned long) __va(real_mode_header->text_start);
 115
 116        set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 117        set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 118        set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 119
 120        return 0;
 121}
 122early_initcall(set_real_mode_permissions);
 123