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
   8 struct real_mode_header *real_mode_header;
   9 u32 *trampoline_cr4_features;
  10
  11 void __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
  29 void __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  */
 100 static 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 }
 122 early_initcall(set_real_mode_permissions);