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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Paul Mundta23ba432007-11-28 20:19:38 +09002 * arch/sh/mm/extable_64.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
4 * Copyright (C) 2003 Richard Curnow
5 * Copyright (C) 2003, 2004 Paul Mundt
6 *
7 * Cloned from the 2.5 SH version..
Paul Mundta23ba432007-11-28 20:19:38 +09008 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/rwsem.h>
14#include <linux/module.h>
15#include <asm/uaccess.h>
16
17extern unsigned long copy_user_memcpy, copy_user_memcpy_end;
18extern void __copy_user_fixup(void);
19
20static const struct exception_table_entry __copy_user_fixup_ex = {
21 .fixup = (unsigned long)&__copy_user_fixup,
22};
23
Paul Mundta23ba432007-11-28 20:19:38 +090024/*
25 * Some functions that may trap due to a bad user-mode address have too
26 * many loads and stores in them to make it at all practical to label
27 * each one and put them all in the main exception table.
28 *
29 * In particular, the fast memcpy routine is like this. It's fix-up is
30 * just to fall back to a slow byte-at-a-time copy, which is handled the
31 * conventional way. So it's functionally OK to just handle any trap
32 * occurring in the fast memcpy with that fixup.
33 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070034static const struct exception_table_entry *check_exception_ranges(unsigned long addr)
35{
36 if ((addr >= (unsigned long)&copy_user_memcpy) &&
37 (addr <= (unsigned long)&copy_user_memcpy_end))
38 return &__copy_user_fixup_ex;
39
40 return NULL;
41}
42
43/* Simple binary search */
44const struct exception_table_entry *
45search_extable(const struct exception_table_entry *first,
46 const struct exception_table_entry *last,
47 unsigned long value)
48{
49 const struct exception_table_entry *mid;
50
51 mid = check_exception_ranges(value);
52 if (mid)
53 return mid;
54
55 while (first <= last) {
56 long diff;
57
58 mid = (last - first) / 2 + first;
59 diff = mid->insn - value;
60 if (diff == 0)
61 return mid;
62 else if (diff < 0)
63 first = mid+1;
64 else
65 last = mid-1;
66 }
67
68 return NULL;
69}
70
71int fixup_exception(struct pt_regs *regs)
72{
73 const struct exception_table_entry *fixup;
74
75 fixup = search_exception_tables(regs->pc);
76 if (fixup) {
77 regs->pc = fixup->fixup;
78 return 1;
79 }
80
81 return 0;
82}