1/*
 2 * arch/sh/mm/extable_64.c
 3 *
 4 * Copyright (C) 2003 Richard Curnow
 5 * Copyright (C) 2003, 2004  Paul Mundt
 6 *
 7 * Cloned from the 2.5 SH version..
 8 *
 9 * This file is subject to the terms and conditions of the GNU General Public
10 * License.  See the file "COPYING" in the main directory of this archive
11 * for more details.
12 */
13#include <linux/bsearch.h>
14#include <linux/rwsem.h>
15#include <linux/extable.h>
16#include <linux/uaccess.h>
17
18extern unsigned long copy_user_memcpy, copy_user_memcpy_end;
19extern void __copy_user_fixup(void);
20
21static const struct exception_table_entry __copy_user_fixup_ex = {
22	.fixup = (unsigned long)&__copy_user_fixup,
23};
24
25/*
26 * Some functions that may trap due to a bad user-mode address have too
27 * many loads and stores in them to make it at all practical to label
28 * each one and put them all in the main exception table.
29 *
30 * In particular, the fast memcpy routine is like this.  It's fix-up is
31 * just to fall back to a slow byte-at-a-time copy, which is handled the
32 * conventional way.  So it's functionally OK to just handle any trap
33 * occurring in the fast memcpy with that fixup.
34 */
35static const struct exception_table_entry *check_exception_ranges(unsigned long addr)
36{
37	if ((addr >= (unsigned long)&copy_user_memcpy) &&
38	    (addr <= (unsigned long)&copy_user_memcpy_end))
39		return &__copy_user_fixup_ex;
40
41	return NULL;
42}
43
44static int cmp_ex_search(const void *key, const void *elt)
45{
46	const struct exception_table_entry *_elt = elt;
47	unsigned long _key = *(unsigned long *)key;
48
49	/* avoid overflow */
50	if (_key > _elt->insn)
51		return 1;
52	if (_key < _elt->insn)
53		return -1;
54	return 0;
55}
56
57/* Simple binary search */
58const struct exception_table_entry *
59search_extable(const struct exception_table_entry *base,
60		 const size_t num,
61		 unsigned long value)
62{
63	const struct exception_table_entry *mid;
64
65	mid = check_exception_ranges(value);
66	if (mid)
67		return mid;
68
69	return bsearch(&value, base, num,
70		       sizeof(struct exception_table_entry), cmp_ex_search);
71}
72
73int fixup_exception(struct pt_regs *regs)
74{
75	const struct exception_table_entry *fixup;
76
77	fixup = search_exception_tables(regs->pc);
78	if (fixup) {
79		regs->pc = fixup->fixup;
80		return 1;
81	}
82
83	return 0;
84}