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/tlbflush.h>
   8
   9 struct real_mode_header *real_mode_header;
  10 u32 *trampoline_cr4_features;
  11
  12 /* Hold the pgd entry used on booting additional CPUs */
  13 pgd_t trampoline_pgd_entry;
  14
  15 void __init reserve_real_mode(void)
  16 {
  17         phys_addr_t mem;
  18         unsigned char *base;
  19         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  20
  21         /* Has to be under 1M so we can execute real-mode AP code. */
  22         mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  23         if (!mem)
  24                 panic("Cannot allocate trampoline\n");
  25
  26         base = __va(mem);
  27         memblock_reserve(mem, size);
  28         real_mode_header = (struct real_mode_header *) base;
  29         printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  30                base, (unsigned long long)mem, size);
  31 }
  32
  33 void __init setup_real_mode(void)
  34 {
  35         u16 real_mode_seg;
  36         const u32 *rel;
  37         u32 count;
  38         unsigned char *base;
  39         unsigned long phys_base;
  40         struct trampoline_header *trampoline_header;
  41         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  42 #ifdef CONFIG_X86_64
  43         u64 *trampoline_pgd;
  44         u64 efer;
  45 #endif
  46
  47         base = (unsigned char *)real_mode_header;
  48
  49         memcpy(base, real_mode_blob, size);
  50
  51         phys_base = __pa(base);
  52         real_mode_seg = phys_base >> 4;
  53
  54         rel = (u32 *) real_mode_relocs;
  55
  56         /* 16-bit segment relocations. */
  57         count = *rel++;
  58         while (count--) {
  59                 u16 *seg = (u16 *) (base + *rel++);
  60                 *seg = real_mode_seg;
  61         }
  62
  63         /* 32-bit linear relocations. */
  64         count = *rel++;
  65         while (count--) {
  66                 u32 *ptr = (u32 *) (base + *rel++);
  67                 *ptr += phys_base;
  68         }
  69
  70         /* Must be perfomed *after* relocation. */
  71         trampoline_header = (struct trampoline_header *)
  72                 __va(real_mode_header->trampoline_header);
  73
  74 #ifdef CONFIG_X86_32
  75         trampoline_header->start = __pa_symbol(startup_32_smp);
  76         trampoline_header->gdt_limit = __BOOT_DS + 7;
  77         trampoline_header->gdt_base = __pa_symbol(boot_gdt);
  78 #else
  79         /*
  80          * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
  81          * so we need to mask it out.
  82          */
  83         rdmsrl(MSR_EFER, efer);
  84         trampoline_header->efer = efer & ~EFER_LMA;
  85
  86         trampoline_header->start = (u64) secondary_startup_64;
  87         trampoline_cr4_features = &trampoline_header->cr4;
  88         *trampoline_cr4_features = mmu_cr4_features;
  89
  90         trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
  91         trampoline_pgd[0] = trampoline_pgd_entry.pgd;
  92         trampoline_pgd[511] = init_level4_pgt[511].pgd;
  93 #endif
  94 }
  95
  96 /*
  97  * reserve_real_mode() gets called very early, to guarantee the
  98  * availability of low memory. This is before the proper kernel page
  99  * tables are set up, so we cannot set page permissions in that
 100  * function. Also trampoline code will be executed by APs so we
 101  * need to mark it executable at do_pre_smp_initcalls() at least,
 102  * thus run it as a early_initcall().
 103  */
 104 static int __init set_real_mode_permissions(void)
 105 {
 106         unsigned char *base = (unsigned char *) real_mode_header;
 107         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 108
 109         size_t ro_size =
 110                 PAGE_ALIGN(real_mode_header->ro_end) -
 111                 __pa(base);
 112
 113         size_t text_size =
 114                 PAGE_ALIGN(real_mode_header->ro_end) -
 115                 real_mode_header->text_start;
 116
 117         unsigned long text_start =
 118                 (unsigned long) __va(real_mode_header->text_start);
 119
 120         set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 121         set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 122         set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 123
 124         return 0;
 125 }
 126 early_initcall(set_real_mode_permissions);