arch/x86/mm/extable.c

   1 #include <linux/module.h>
   2 #include <linux/spinlock.h>
   3 #include <asm/uaccess.h>
   4
   5
   6 int fixup_exception(struct pt_regs *regs)
   7 {
   8         const struct exception_table_entry *fixup;
   9
  10 #ifdef CONFIG_PNPBIOS
  11         if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
  12                 extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
  13                 extern u32 pnp_bios_is_utter_crap;
  14                 pnp_bios_is_utter_crap = 1;
  15                 printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
  16                 __asm__ volatile(
  17                         "movl %0, %%esp\n\t"
  18                         "jmp *%1\n\t"
  19                         : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
  20                 panic("do_trap: can't hit this");
  21         }
  22 #endif
  23
  24         fixup = search_exception_tables(regs->ip);
  25         if (fixup) {
  26                 regs->ip = fixup->fixup;
  27                 return 1;
  28         }
  29
  30         return 0;
  31 }
  32
  33 #ifdef CONFIG_X86_64
  34 /*
  35  * Need to defined our own search_extable on X86_64 to work around
  36  * a B stepping K8 bug.
  37  */
  38 const struct exception_table_entry *
  39 search_extable(const struct exception_table_entry *first,
  40                const struct exception_table_entry *last,
  41                unsigned long value)
  42 {
  43         /* B stepping K8 bug */
  44         if ((value >> 32) == 0)
  45                 value |= 0xffffffffUL << 32;
  46
  47         while (first <= last) {
  48                 const struct exception_table_entry *mid;
  49                 long diff;
  50
  51                 mid = (last - first) / 2 + first;
  52                 diff = mid->insn - value;
  53                 if (diff == 0)
  54                         return mid;
  55                 else if (diff < 0)
  56                         first = mid+1;
  57                 else
  58                         last = mid-1;
  59         }
  60         return NULL;
  61 }
  62 #endif