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 /* If fixup is less than 16, it means uaccess error */
27 if (fixup->fixup < 16) {
28 current_thread_info()->uaccess_err = -EFAULT;
29 regs->ip += fixup->fixup;
30 return 1;
31 }
32 regs->ip = fixup->fixup;
33 return 1;
34 }
35
36 return 0;
37 }
38
39 #ifdef CONFIG_X86_64
40 /*
41 * Need to defined our own search_extable on X86_64 to work around
42 * a B stepping K8 bug.
43 */
44 const struct exception_table_entry *
45 search_extable(const struct exception_table_entry *first,
46 const struct exception_table_entry *last,
47 unsigned long value)
48 {
49 /* B stepping K8 bug */
50 if ((value >> 32) == 0)
51 value |= 0xffffffffUL << 32;
52
53 while (first <= last) {
54 const struct exception_table_entry *mid;
55 long diff;
56
57 mid = (last - first) / 2 + first;
58 diff = mid->insn - value;
59 if (diff == 0)
60 return mid;
61 else if (diff < 0)
62 first = mid+1;
63 else
64 last = mid-1;
65 }
66 return NULL;
67 }
68 #endif
69
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