arch/x86/realmode/init.c

   1 #include <linux/io.h>
   2 #include <linux/slab.h>
   3 #include <linux/memblock.h>
   4
   5 #include <asm/set_memory.h>
   6 #include <asm/pgtable.h>
   7 #include <asm/realmode.h>
   8 #include <asm/tlbflush.h>
   9
  10 struct real_mode_header *real_mode_header;
  11 u32 *trampoline_cr4_features;
  12
  13 /* Hold the pgd entry used on booting additional CPUs */
  14 pgd_t trampoline_pgd_entry;
  15
  16 void __init set_real_mode_mem(phys_addr_t mem, size_t size)
  17 {
  18         void *base = __va(mem);
  19
  20         real_mode_header = (struct real_mode_header *) base;
  21         printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  22                base, (unsigned long long)mem, size);
  23 }
  24
  25 void __init reserve_real_mode(void)
  26 {
  27         phys_addr_t mem;
  28         size_t size = real_mode_size_needed();
  29
  30         if (!size)
  31                 return;
  32
  33         WARN_ON(slab_is_available());
  34
  35         /* Has to be under 1M so we can execute real-mode AP code. */
  36         mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  37         if (!mem) {
  38                 pr_info("No sub-1M memory is available for the trampoline\n");
  39                 return;
  40         }
  41
  42         memblock_reserve(mem, size);
  43         set_real_mode_mem(mem, size);
  44 }
  45
  46 static void __init setup_real_mode(void)
  47 {
  48         u16 real_mode_seg;
  49         const u32 *rel;
  50         u32 count;
  51         unsigned char *base;
  52         unsigned long phys_base;
  53         struct trampoline_header *trampoline_header;
  54         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  55 #ifdef CONFIG_X86_64
  56         u64 *trampoline_pgd;
  57         u64 efer;
  58 #endif
  59
  60         base = (unsigned char *)real_mode_header;
  61
  62         memcpy(base, real_mode_blob, size);
  63
  64         phys_base = __pa(base);
  65         real_mode_seg = phys_base >> 4;
  66
  67         rel = (u32 *) real_mode_relocs;
  68
  69         /* 16-bit segment relocations. */
  70         count = *rel++;
  71         while (count--) {
  72                 u16 *seg = (u16 *) (base + *rel++);
  73                 *seg = real_mode_seg;
  74         }
  75
  76         /* 32-bit linear relocations. */
  77         count = *rel++;
  78         while (count--) {
  79                 u32 *ptr = (u32 *) (base + *rel++);
  80                 *ptr += phys_base;
  81         }
  82
  83         /* Must be perfomed *after* relocation. */
  84         trampoline_header = (struct trampoline_header *)
  85                 __va(real_mode_header->trampoline_header);
  86
  87 #ifdef CONFIG_X86_32
  88         trampoline_header->start = __pa_symbol(startup_32_smp);
  89         trampoline_header->gdt_limit = __BOOT_DS + 7;
  90         trampoline_header->gdt_base = __pa_symbol(boot_gdt);
  91 #else
  92         /*
  93          * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
  94          * so we need to mask it out.
  95          */
  96         rdmsrl(MSR_EFER, efer);
  97         trampoline_header->efer = efer & ~EFER_LMA;
  98
  99         trampoline_header->start = (u64) secondary_startup_64;
 100         trampoline_cr4_features = &trampoline_header->cr4;
 101         *trampoline_cr4_features = mmu_cr4_features;
 102
 103         trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
 104         trampoline_pgd[0] = trampoline_pgd_entry.pgd;
 105         trampoline_pgd[511] = init_top_pgt[511].pgd;
 106 #endif
 107 }
 108
 109 /*
 110  * reserve_real_mode() gets called very early, to guarantee the
 111  * availability of low memory. This is before the proper kernel page
 112  * tables are set up, so we cannot set page permissions in that
 113  * function. Also trampoline code will be executed by APs so we
 114  * need to mark it executable at do_pre_smp_initcalls() at least,
 115  * thus run it as a early_initcall().
 116  */
 117 static void __init set_real_mode_permissions(void)
 118 {
 119         unsigned char *base = (unsigned char *) real_mode_header;
 120         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 121
 122         size_t ro_size =
 123                 PAGE_ALIGN(real_mode_header->ro_end) -
 124                 __pa(base);
 125
 126         size_t text_size =
 127                 PAGE_ALIGN(real_mode_header->ro_end) -
 128                 real_mode_header->text_start;
 129
 130         unsigned long text_start =
 131                 (unsigned long) __va(real_mode_header->text_start);
 132
 133         set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 134         set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 135         set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 136 }
 137
 138 static int __init init_real_mode(void)
 139 {
 140         if (!real_mode_header)
 141                 panic("Real mode trampoline was not allocated");
 142
 143         setup_real_mode();
 144         set_real_mode_permissions();
 145
 146         return 0;
 147 }
 148 early_initcall(init_real_mode);