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/module.h>
13#include <linux/init.h>
14#include <linux/sort.h>
15#include <asm/uaccess.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
16
17#ifndef ARCH_HAS_SORT_EXTABLE
18/*
19 * The exception table needs to be sorted so that the binary
20 * search that we use to find entries in it works properly.
21 * This is used both for the kernel exception table and for
22 * the exception tables of modules that get loaded.
23 */
24static int cmp_ex(const void *a, const void *b)
25{
26	const struct exception_table_entry *x = a, *y = b;
27
28	/* avoid overflow */
29	if (x->insn > y->insn)
30		return 1;
31	if (x->insn < y->insn)
32		return -1;
33	return 0;
34}
35
36void sort_extable(struct exception_table_entry *start,
37		  struct exception_table_entry *finish)
38{
39	sort(start, finish - start, sizeof(struct exception_table_entry),
40	     cmp_ex, NULL);
41}
42
43#ifdef CONFIG_MODULES
44/*
45 * If the exception table is sorted, any referring to the module init
46 * will be at the beginning or the end.
47 */
48void trim_init_extable(struct module *m)
49{
50	/*trim the beginning*/
51	while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {
 
52		m->extable++;
53		m->num_exentries--;
54	}
55	/*trim the end*/
56	while (m->num_exentries &&
57		within_module_init(m->extable[m->num_exentries-1].insn, m))
 
58		m->num_exentries--;
59}
60#endif /* CONFIG_MODULES */
61#endif /* !ARCH_HAS_SORT_EXTABLE */
62
63#ifndef ARCH_HAS_SEARCH_EXTABLE
 
 
 
 
 
 
 
 
 
 
 
 
64/*
65 * Search one exception table for an entry corresponding to the
66 * given instruction address, and return the address of the entry,
67 * or NULL if none is found.
68 * We use a binary search, and thus we assume that the table is
69 * already sorted.
70 */
71const struct exception_table_entry *
72search_extable(const struct exception_table_entry *first,
73	       const struct exception_table_entry *last,
74	       unsigned long value)
75{
76	while (first <= last) {
77		const struct exception_table_entry *mid;
78
79		mid = ((last - first) >> 1) + first;
80		/*
81		 * careful, the distance between value and insn
82		 * can be larger than MAX_LONG:
83		 */
84		if (mid->insn < value)
85			first = mid + 1;
86		else if (mid->insn > value)
87			last = mid - 1;
88		else
89			return mid;
90        }
91        return NULL;
92}
93#endif

  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}