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