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 <linux/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
56static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
57{
58	return (unsigned long)&x->addr + x->addr;
59}
60
61#ifdef CONFIG_MODULES
62/*
63 * Any entry referring to the module init will be at the beginning or
64 * the end.
65 */
66void trim_init_extable(struct module *m)
67{
68	/*trim the beginning*/
69	while (m->num_exentries &&
70	       within_module_init(ex_to_addr(&m->extable[0]), m)) {
71		m->extable++;
72		m->num_exentries--;
73	}
74	/*trim the end*/
75	while (m->num_exentries &&
76	       within_module_init(ex_to_addr(&m->extable[m->num_exentries-1]),
77				  m))
78		m->num_exentries--;
79}
80#endif /* CONFIG_MODULES */
81
82const struct exception_table_entry *
83search_extable (const struct exception_table_entry *first,
84		const struct exception_table_entry *last,
85		unsigned long ip)
86{
87	const struct exception_table_entry *mid;
88	unsigned long mid_ip;
89	long diff;
90
91        while (first <= last) {
92		mid = &first[(last - first)/2];
93		mid_ip = (u64) &mid->addr + mid->addr;
94		diff = mid_ip - ip;
95                if (diff == 0)
96                        return mid;
97                else if (diff < 0)
98                        first = mid + 1;
99                else
100                        last = mid - 1;
101        }
102        return NULL;
103}
104
105void
106ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
107{
108	long fix = (u64) &e->cont + e->cont;
109
110	regs->r8 = -EFAULT;
111	if (fix & 4)
112		regs->r9 = 0;
113	regs->cr_iip = fix & ~0xf;
114	ia64_psr(regs)->ri = fix & 0x3;		/* set continuation slot number */
115}
116