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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
3 *
4 * Copyright (C) 2004 Paul Mackerras, IBM Corp.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sort.h>
15#include <asm/uaccess.h>
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#ifndef ARCH_HAS_SORT_EXTABLE
18/*
19 * The exception table needs to be sorted so that the binary
20 * search that we use to find entries in it works properly.
21 * This is used both for the kernel exception table and for
22 * the exception tables of modules that get loaded.
23 */
24static int cmp_ex(const void *a, const void *b)
25{
26 const struct exception_table_entry *x = a, *y = b;
27
28 /* avoid overflow */
29 if (x->insn > y->insn)
30 return 1;
31 if (x->insn < y->insn)
32 return -1;
33 return 0;
34}
35
36void sort_extable(struct exception_table_entry *start,
37 struct exception_table_entry *finish)
38{
39 sort(start, finish - start, sizeof(struct exception_table_entry),
40 cmp_ex, NULL);
41}
42#endif
43
44#ifndef ARCH_HAS_SEARCH_EXTABLE
45/*
46 * Search one exception table for an entry corresponding to the
47 * given instruction address, and return the address of the entry,
48 * or NULL if none is found.
49 * We use a binary search, and thus we assume that the table is
50 * already sorted.
51 */
52const struct exception_table_entry *
53search_extable(const struct exception_table_entry *first,
54 const struct exception_table_entry *last,
55 unsigned long value)
56{
57 while (first <= last) {
58 const struct exception_table_entry *mid;
59
Eric Dumazet15ae02b2008-02-06 01:37:49 -080060 mid = ((last - first) >> 1) + first;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 /*
Eric Dumazet15ae02b2008-02-06 01:37:49 -080062 * careful, the distance between value and insn
63 * can be larger than MAX_LONG:
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 */
65 if (mid->insn < value)
66 first = mid + 1;
67 else if (mid->insn > value)
68 last = mid - 1;
69 else
70 return mid;
71 }
72 return NULL;
73}
74#endif