Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * 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 | ||
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/sort.h> | |
15 | #include <asm/uaccess.h> | |
16 | ||
27375cf7 AB |
17 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
18 | #define ex_to_insn(x) ((x)->insn) | |
19 | #else | |
20 | static inline unsigned long ex_to_insn(const struct exception_table_entry *x) | |
21 | { | |
22 | return (unsigned long)&x->insn + x->insn; | |
23 | } | |
24 | #endif | |
25 | ||
1da177e4 | 26 | #ifndef ARCH_HAS_SORT_EXTABLE |
27375cf7 AB |
27 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
28 | #define swap_ex NULL | |
29 | #else | |
30 | static void swap_ex(void *a, void *b, int size) | |
31 | { | |
32 | struct exception_table_entry *x = a, *y = b, tmp; | |
33 | int delta = b - a; | |
34 | ||
35 | tmp = *x; | |
36 | x->insn = y->insn + delta; | |
37 | y->insn = tmp.insn - delta; | |
38 | ||
39 | #ifdef swap_ex_entry_fixup | |
40 | swap_ex_entry_fixup(x, y, tmp, delta); | |
41 | #else | |
42 | x->fixup = y->fixup + delta; | |
43 | y->fixup = tmp.fixup - delta; | |
44 | #endif | |
45 | } | |
46 | #endif /* ARCH_HAS_RELATIVE_EXTABLE */ | |
47 | ||
1da177e4 LT |
48 | /* |
49 | * The exception table needs to be sorted so that the binary | |
50 | * search that we use to find entries in it works properly. | |
51 | * This is used both for the kernel exception table and for | |
52 | * the exception tables of modules that get loaded. | |
53 | */ | |
54 | static int cmp_ex(const void *a, const void *b) | |
55 | { | |
56 | const struct exception_table_entry *x = a, *y = b; | |
57 | ||
58 | /* avoid overflow */ | |
27375cf7 | 59 | if (ex_to_insn(x) > ex_to_insn(y)) |
1da177e4 | 60 | return 1; |
27375cf7 | 61 | if (ex_to_insn(x) < ex_to_insn(y)) |
1da177e4 LT |
62 | return -1; |
63 | return 0; | |
64 | } | |
65 | ||
66 | void sort_extable(struct exception_table_entry *start, | |
67 | struct exception_table_entry *finish) | |
68 | { | |
69 | sort(start, finish - start, sizeof(struct exception_table_entry), | |
27375cf7 | 70 | cmp_ex, swap_ex); |
1da177e4 | 71 | } |
ad6561df RR |
72 | |
73 | #ifdef CONFIG_MODULES | |
74 | /* | |
75 | * If the exception table is sorted, any referring to the module init | |
76 | * will be at the beginning or the end. | |
77 | */ | |
78 | void trim_init_extable(struct module *m) | |
79 | { | |
80 | /*trim the beginning*/ | |
27375cf7 AB |
81 | while (m->num_exentries && |
82 | within_module_init(ex_to_insn(&m->extable[0]), m)) { | |
ad6561df RR |
83 | m->extable++; |
84 | m->num_exentries--; | |
85 | } | |
86 | /*trim the end*/ | |
87 | while (m->num_exentries && | |
27375cf7 AB |
88 | within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), |
89 | m)) | |
ad6561df RR |
90 | m->num_exentries--; |
91 | } | |
92 | #endif /* CONFIG_MODULES */ | |
93 | #endif /* !ARCH_HAS_SORT_EXTABLE */ | |
1da177e4 LT |
94 | |
95 | #ifndef ARCH_HAS_SEARCH_EXTABLE | |
96 | /* | |
97 | * Search one exception table for an entry corresponding to the | |
98 | * given instruction address, and return the address of the entry, | |
99 | * or NULL if none is found. | |
100 | * We use a binary search, and thus we assume that the table is | |
101 | * already sorted. | |
102 | */ | |
103 | const struct exception_table_entry * | |
104 | search_extable(const struct exception_table_entry *first, | |
105 | const struct exception_table_entry *last, | |
106 | unsigned long value) | |
107 | { | |
108 | while (first <= last) { | |
109 | const struct exception_table_entry *mid; | |
110 | ||
15ae02ba | 111 | mid = ((last - first) >> 1) + first; |
1da177e4 | 112 | /* |
15ae02ba ED |
113 | * careful, the distance between value and insn |
114 | * can be larger than MAX_LONG: | |
1da177e4 | 115 | */ |
27375cf7 | 116 | if (ex_to_insn(mid) < value) |
1da177e4 | 117 | first = mid + 1; |
27375cf7 | 118 | else if (ex_to_insn(mid) > value) |
1da177e4 LT |
119 | last = mid - 1; |
120 | else | |
121 | return mid; | |
27375cf7 AB |
122 | } |
123 | return NULL; | |
1da177e4 LT |
124 | } |
125 | #endif |