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