1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
5 * Copyright (C) 2004 Paul Mackerras, IBM Corp.
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>
15 #ifndef ARCH_HAS_RELATIVE_EXTABLE
16 #define ex_to_insn(x) ((x)->insn)
18 static inline unsigned long ex_to_insn(const struct exception_table_entry *x)
20 return (unsigned long)&x->insn + x->insn;
24 #ifndef ARCH_HAS_RELATIVE_EXTABLE
27 static void swap_ex(void *a, void *b, int size)
29 struct exception_table_entry *x = a, *y = b, tmp;
33 x->insn = y->insn + delta;
34 y->insn = tmp.insn - delta;
36 #ifdef swap_ex_entry_fixup
37 swap_ex_entry_fixup(x, y, tmp, delta);
39 x->fixup = y->fixup + delta;
40 y->fixup = tmp.fixup - delta;
43 #endif /* ARCH_HAS_RELATIVE_EXTABLE */
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.
51 static int cmp_ex_sort(const void *a, const void *b)
53 const struct exception_table_entry *x = a, *y = b;
56 if (ex_to_insn(x) > ex_to_insn(y))
58 if (ex_to_insn(x) < ex_to_insn(y))
63 void sort_extable(struct exception_table_entry *start,
64 struct exception_table_entry *finish)
66 sort(start, finish - start, sizeof(struct exception_table_entry),
67 cmp_ex_sort, swap_ex);
72 * If the exception table is sorted, any referring to the module init
73 * will be at the beginning or the end.
75 void trim_init_extable(struct module *m)
77 /*trim the beginning*/
78 while (m->num_exentries &&
79 within_module_init(ex_to_insn(&m->extable[0]), m)) {
84 while (m->num_exentries &&
85 within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),
89 #endif /* CONFIG_MODULES */
91 static int cmp_ex_search(const void *key, const void *elt)
93 const struct exception_table_entry *_elt = elt;
94 unsigned long _key = *(unsigned long *)key;
97 if (_key > ex_to_insn(_elt))
99 if (_key < ex_to_insn(_elt))
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
111 const struct exception_table_entry *
112 search_extable(const struct exception_table_entry *base,
116 return bsearch(&value, base, num,
117 sizeof(struct exception_table_entry), cmp_ex_search);