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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 | 2 | /* |
1da177e4 LT |
3 | * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. |
4 | * | |
5 | * Copyright (C) 2004 Paul Mackerras, IBM Corp. | |
1da177e4 LT |
6 | */ |
7 | ||
a94c33dd | 8 | #include <linux/bsearch.h> |
1da177e4 LT |
9 | #include <linux/module.h> |
10 | #include <linux/init.h> | |
11 | #include <linux/sort.h> | |
7c0f6ba6 | 12 | #include <linux/uaccess.h> |
8e72a7a4 | 13 | #include <linux/extable.h> |
1da177e4 | 14 | |
a272858a AB |
15 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
16 | #define ex_to_insn(x) ((x)->insn) | |
17 | #else | |
18 | static inline unsigned long ex_to_insn(const struct exception_table_entry *x) | |
19 | { | |
20 | return (unsigned long)&x->insn + x->insn; | |
21 | } | |
22 | #endif | |
23 | ||
1da177e4 | 24 | #ifndef ARCH_HAS_SORT_EXTABLE |
a272858a AB |
25 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
26 | #define swap_ex NULL | |
27 | #else | |
28 | static void swap_ex(void *a, void *b, int size) | |
29 | { | |
30 | struct exception_table_entry *x = a, *y = b, tmp; | |
31 | int delta = b - a; | |
32 | ||
33 | tmp = *x; | |
34 | x->insn = y->insn + delta; | |
35 | y->insn = tmp.insn - delta; | |
36 | ||
37 | #ifdef swap_ex_entry_fixup | |
38 | swap_ex_entry_fixup(x, y, tmp, delta); | |
39 | #else | |
40 | x->fixup = y->fixup + delta; | |
41 | y->fixup = tmp.fixup - delta; | |
42 | #endif | |
43 | } | |
44 | #endif /* ARCH_HAS_RELATIVE_EXTABLE */ | |
45 | ||
1da177e4 LT |
46 | /* |
47 | * The exception table needs to be sorted so that the binary | |
48 | * search that we use to find entries in it works properly. | |
49 | * This is used both for the kernel exception table and for | |
50 | * the exception tables of modules that get loaded. | |
51 | */ | |
a94c33dd | 52 | static int cmp_ex_sort(const void *a, const void *b) |
1da177e4 LT |
53 | { |
54 | const struct exception_table_entry *x = a, *y = b; | |
55 | ||
56 | /* avoid overflow */ | |
a272858a | 57 | if (ex_to_insn(x) > ex_to_insn(y)) |
1da177e4 | 58 | return 1; |
a272858a | 59 | if (ex_to_insn(x) < ex_to_insn(y)) |
1da177e4 LT |
60 | return -1; |
61 | return 0; | |
62 | } | |
63 | ||
64 | void sort_extable(struct exception_table_entry *start, | |
65 | struct exception_table_entry *finish) | |
66 | { | |
67 | sort(start, finish - start, sizeof(struct exception_table_entry), | |
a94c33dd | 68 | cmp_ex_sort, swap_ex); |
1da177e4 | 69 | } |
ad6561df RR |
70 | |
71 | #ifdef CONFIG_MODULES | |
72 | /* | |
73 | * If the exception table is sorted, any referring to the module init | |
74 | * will be at the beginning or the end. | |
75 | */ | |
76 | void trim_init_extable(struct module *m) | |
77 | { | |
78 | /*trim the beginning*/ | |
a272858a AB |
79 | while (m->num_exentries && |
80 | within_module_init(ex_to_insn(&m->extable[0]), m)) { | |
ad6561df RR |
81 | m->extable++; |
82 | m->num_exentries--; | |
83 | } | |
84 | /*trim the end*/ | |
85 | while (m->num_exentries && | |
a272858a AB |
86 | within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), |
87 | m)) | |
ad6561df RR |
88 | m->num_exentries--; |
89 | } | |
90 | #endif /* CONFIG_MODULES */ | |
91 | #endif /* !ARCH_HAS_SORT_EXTABLE */ | |
1da177e4 LT |
92 | |
93 | #ifndef ARCH_HAS_SEARCH_EXTABLE | |
a94c33dd TM |
94 | |
95 | static int cmp_ex_search(const void *key, const void *elt) | |
96 | { | |
97 | const struct exception_table_entry *_elt = elt; | |
98 | unsigned long _key = *(unsigned long *)key; | |
99 | ||
100 | /* avoid overflow */ | |
101 | if (_key > ex_to_insn(_elt)) | |
102 | return 1; | |
103 | if (_key < ex_to_insn(_elt)) | |
104 | return -1; | |
105 | return 0; | |
106 | } | |
107 | ||
1da177e4 LT |
108 | /* |
109 | * Search one exception table for an entry corresponding to the | |
110 | * given instruction address, and return the address of the entry, | |
111 | * or NULL if none is found. | |
112 | * We use a binary search, and thus we assume that the table is | |
113 | * already sorted. | |
114 | */ | |
115 | const struct exception_table_entry * | |
a94c33dd TM |
116 | search_extable(const struct exception_table_entry *base, |
117 | const size_t num, | |
1da177e4 LT |
118 | unsigned long value) |
119 | { | |
a94c33dd TM |
120 | return bsearch(&value, base, num, |
121 | sizeof(struct exception_table_entry), cmp_ex_search); | |
1da177e4 LT |
122 | } |
123 | #endif |