xref: /openbmc/linux/arch/x86/mm/extable.c (revision 22246614)
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
63