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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
12#include <linux/config.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/sort.h>
16#include <asm/uaccess.h>
17
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#ifndef ARCH_HAS_SORT_EXTABLE
19/*
20 * The exception table needs to be sorted so that the binary
21 * search that we use to find entries in it works properly.
22 * This is used both for the kernel exception table and for
23 * the exception tables of modules that get loaded.
24 */
25static int cmp_ex(const void *a, const void *b)
26{
27 const struct exception_table_entry *x = a, *y = b;
28
29 /* avoid overflow */
30 if (x->insn > y->insn)
31 return 1;
32 if (x->insn < y->insn)
33 return -1;
34 return 0;
35}
36
37void sort_extable(struct exception_table_entry *start,
38 struct exception_table_entry *finish)
39{
40 sort(start, finish - start, sizeof(struct exception_table_entry),
41 cmp_ex, NULL);
42}
43#endif
44
45#ifndef ARCH_HAS_SEARCH_EXTABLE
46/*
47 * Search one exception table for an entry corresponding to the
48 * given instruction address, and return the address of the entry,
49 * or NULL if none is found.
50 * We use a binary search, and thus we assume that the table is
51 * already sorted.
52 */
53const struct exception_table_entry *
54search_extable(const struct exception_table_entry *first,
55 const struct exception_table_entry *last,
56 unsigned long value)
57{
58 while (first <= last) {
59 const struct exception_table_entry *mid;
60
61 mid = (last - first) / 2 + first;
62 /*
63 * careful, the distance between entries can be
64 * larger than 2GB:
65 */
66 if (mid->insn < value)
67 first = mid + 1;
68 else if (mid->insn > value)
69 last = mid - 1;
70 else
71 return mid;
72 }
73 return NULL;
74}
75#endif