1/*
2 * Kernel exception handling table support.  Derived from arch/alpha/mm/extable.c.
3 *
4 * Copyright (C) 1998, 1999, 2001-2002, 2004 Hewlett-Packard Co
5 *	David Mosberger-Tang <davidm@hpl.hp.com>
6 */
7
8#include <linux/sort.h>
9
10#include <asm/uaccess.h>
11#include <asm/module.h>
12
13static int cmp_ex(const void *a, const void *b)
14{
15	const struct exception_table_entry *l = a, *r = b;
16	u64 lip = (u64) &l->addr + l->addr;
17	u64 rip = (u64) &r->addr + r->addr;
18
19	/* avoid overflow */
20	if (lip > rip)
21		return 1;
22	if (lip < rip)
23		return -1;
24	return 0;
25}
26
27static void swap_ex(void *a, void *b, int size)
28{
29	struct exception_table_entry *l = a, *r = b, tmp;
30	u64 delta = (u64) r - (u64) l;
31
32	tmp = *l;
33	l->addr = r->addr + delta;
34	l->cont = r->cont + delta;
35	r->addr = tmp.addr - delta;
36	r->cont = tmp.cont - delta;
37}
38
39/*
40 * Sort the exception table. It's usually already sorted, but there
41 * may be unordered entries due to multiple text sections (such as the
42 * .init text section). Note that the exception-table-entries contain
43 * location-relative addresses, which requires a bit of care during
44 * sorting to avoid overflows in the offset members (e.g., it would
45 * not be safe to make a temporary copy of an exception-table entry on
46 * the stack, because the stack may be more than 2GB away from the
47 * exception-table).
48 */
49void sort_extable (struct exception_table_entry *start,
50		   struct exception_table_entry *finish)
51{
52	sort(start, finish - start, sizeof(struct exception_table_entry),
53	     cmp_ex, swap_ex);
54}
55
56const struct exception_table_entry *
57search_extable (const struct exception_table_entry *first,
58		const struct exception_table_entry *last,
59		unsigned long ip)
60{
61	const struct exception_table_entry *mid;
62	unsigned long mid_ip;
63	long diff;
64
65        while (first <= last) {
66		mid = &first[(last - first)/2];
67		mid_ip = (u64) &mid->addr + mid->addr;
68		diff = mid_ip - ip;
69                if (diff == 0)
70                        return mid;
71                else if (diff < 0)
72                        first = mid + 1;
73                else
74                        last = mid - 1;
75        }
76        return NULL;
77}
78
79void
80ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
81{
82	long fix = (u64) &e->cont + e->cont;
83
84	regs->r8 = -EFAULT;
85	if (fix & 4)
86		regs->r9 = 0;
87	regs->cr_iip = fix & ~0xf;
88	ia64_psr(regs)->ri = fix & 0x3;		/* set continuation slot number */
89}
90