Loading...
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
4 *
5 * Copyright (C) 2004 Paul Mackerras, IBM Corp.
6 */
7
8#include <linux/bsearch.h>
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/sort.h>
12#include <linux/uaccess.h>
13#include <linux/extable.h>
14
15#ifndef ARCH_HAS_RELATIVE_EXTABLE
16#define ex_to_insn(x) ((x)->insn)
17#else
18static 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
24#ifndef ARCH_HAS_RELATIVE_EXTABLE
25#define swap_ex NULL
26#else
27static void swap_ex(void *a, void *b, int size)
28{
29 struct exception_table_entry *x = a, *y = b, tmp;
30 int delta = b - a;
31
32 tmp = *x;
33 x->insn = y->insn + delta;
34 y->insn = tmp.insn - delta;
35
36#ifdef swap_ex_entry_fixup
37 swap_ex_entry_fixup(x, y, tmp, delta);
38#else
39 x->fixup = y->fixup + delta;
40 y->fixup = tmp.fixup - delta;
41#endif
42}
43#endif /* ARCH_HAS_RELATIVE_EXTABLE */
44
45/*
46 * The exception table needs to be sorted so that the binary
47 * search that we use to find entries in it works properly.
48 * This is used both for the kernel exception table and for
49 * the exception tables of modules that get loaded.
50 */
51static int cmp_ex_sort(const void *a, const void *b)
52{
53 const struct exception_table_entry *x = a, *y = b;
54
55 /* avoid overflow */
56 if (ex_to_insn(x) > ex_to_insn(y))
57 return 1;
58 if (ex_to_insn(x) < ex_to_insn(y))
59 return -1;
60 return 0;
61}
62
63void sort_extable(struct exception_table_entry *start,
64 struct exception_table_entry *finish)
65{
66 sort(start, finish - start, sizeof(struct exception_table_entry),
67 cmp_ex_sort, swap_ex);
68}
69
70#ifdef CONFIG_MODULES
71/*
72 * If the exception table is sorted, any referring to the module init
73 * will be at the beginning or the end.
74 */
75void trim_init_extable(struct module *m)
76{
77 /*trim the beginning*/
78 while (m->num_exentries &&
79 within_module_init(ex_to_insn(&m->extable[0]), m)) {
80 m->extable++;
81 m->num_exentries--;
82 }
83 /*trim the end*/
84 while (m->num_exentries &&
85 within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),
86 m))
87 m->num_exentries--;
88}
89#endif /* CONFIG_MODULES */
90
91static int cmp_ex_search(const void *key, const void *elt)
92{
93 const struct exception_table_entry *_elt = elt;
94 unsigned long _key = *(unsigned long *)key;
95
96 /* avoid overflow */
97 if (_key > ex_to_insn(_elt))
98 return 1;
99 if (_key < ex_to_insn(_elt))
100 return -1;
101 return 0;
102}
103
104/*
105 * Search one exception table for an entry corresponding to the
106 * given instruction address, and return the address of the entry,
107 * or NULL if none is found.
108 * We use a binary search, and thus we assume that the table is
109 * already sorted.
110 */
111const struct exception_table_entry *
112search_extable(const struct exception_table_entry *base,
113 const size_t num,
114 unsigned long value)
115{
116 return bsearch(&value, base, num,
117 sizeof(struct exception_table_entry), cmp_ex_search);
118}
1/*
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
12#include <linux/bsearch.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/sort.h>
16#include <linux/uaccess.h>
17
18#ifndef ARCH_HAS_RELATIVE_EXTABLE
19#define ex_to_insn(x) ((x)->insn)
20#else
21static inline unsigned long ex_to_insn(const struct exception_table_entry *x)
22{
23 return (unsigned long)&x->insn + x->insn;
24}
25#endif
26
27#ifndef ARCH_HAS_SORT_EXTABLE
28#ifndef ARCH_HAS_RELATIVE_EXTABLE
29#define swap_ex NULL
30#else
31static void swap_ex(void *a, void *b, int size)
32{
33 struct exception_table_entry *x = a, *y = b, tmp;
34 int delta = b - a;
35
36 tmp = *x;
37 x->insn = y->insn + delta;
38 y->insn = tmp.insn - delta;
39
40#ifdef swap_ex_entry_fixup
41 swap_ex_entry_fixup(x, y, tmp, delta);
42#else
43 x->fixup = y->fixup + delta;
44 y->fixup = tmp.fixup - delta;
45#endif
46}
47#endif /* ARCH_HAS_RELATIVE_EXTABLE */
48
49/*
50 * The exception table needs to be sorted so that the binary
51 * search that we use to find entries in it works properly.
52 * This is used both for the kernel exception table and for
53 * the exception tables of modules that get loaded.
54 */
55static int cmp_ex_sort(const void *a, const void *b)
56{
57 const struct exception_table_entry *x = a, *y = b;
58
59 /* avoid overflow */
60 if (ex_to_insn(x) > ex_to_insn(y))
61 return 1;
62 if (ex_to_insn(x) < ex_to_insn(y))
63 return -1;
64 return 0;
65}
66
67void sort_extable(struct exception_table_entry *start,
68 struct exception_table_entry *finish)
69{
70 sort(start, finish - start, sizeof(struct exception_table_entry),
71 cmp_ex_sort, swap_ex);
72}
73
74#ifdef CONFIG_MODULES
75/*
76 * If the exception table is sorted, any referring to the module init
77 * will be at the beginning or the end.
78 */
79void trim_init_extable(struct module *m)
80{
81 /*trim the beginning*/
82 while (m->num_exentries &&
83 within_module_init(ex_to_insn(&m->extable[0]), m)) {
84 m->extable++;
85 m->num_exentries--;
86 }
87 /*trim the end*/
88 while (m->num_exentries &&
89 within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),
90 m))
91 m->num_exentries--;
92}
93#endif /* CONFIG_MODULES */
94#endif /* !ARCH_HAS_SORT_EXTABLE */
95
96#ifndef ARCH_HAS_SEARCH_EXTABLE
97
98static int cmp_ex_search(const void *key, const void *elt)
99{
100 const struct exception_table_entry *_elt = elt;
101 unsigned long _key = *(unsigned long *)key;
102
103 /* avoid overflow */
104 if (_key > ex_to_insn(_elt))
105 return 1;
106 if (_key < ex_to_insn(_elt))
107 return -1;
108 return 0;
109}
110
111/*
112 * Search one exception table for an entry corresponding to the
113 * given instruction address, and return the address of the entry,
114 * or NULL if none is found.
115 * We use a binary search, and thus we assume that the table is
116 * already sorted.
117 */
118const struct exception_table_entry *
119search_extable(const struct exception_table_entry *base,
120 const size_t num,
121 unsigned long value)
122{
123 return bsearch(&value, base, num,
124 sizeof(struct exception_table_entry), cmp_ex_search);
125}
126#endif