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1da177e4 | 1 | /* |
a23ba435 | 2 | * arch/sh/mm/extable_64.c |
1da177e4 LT |
3 | * |
4 | * Copyright (C) 2003 Richard Curnow | |
5 | * Copyright (C) 2003, 2004 Paul Mundt | |
6 | * | |
7 | * Cloned from the 2.5 SH version.. | |
a23ba435 PM |
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. | |
1da177e4 | 12 | */ |
a94c33dd | 13 | #include <linux/bsearch.h> |
1da177e4 | 14 | #include <linux/rwsem.h> |
d92280d1 | 15 | #include <linux/extable.h> |
7c0f6ba6 | 16 | #include <linux/uaccess.h> |
1da177e4 LT |
17 | |
18 | extern unsigned long copy_user_memcpy, copy_user_memcpy_end; | |
19 | extern void __copy_user_fixup(void); | |
20 | ||
21 | static const struct exception_table_entry __copy_user_fixup_ex = { | |
22 | .fixup = (unsigned long)&__copy_user_fixup, | |
23 | }; | |
24 | ||
a23ba435 PM |
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 | */ | |
1da177e4 LT |
35 | static const struct exception_table_entry *check_exception_ranges(unsigned long addr) |
36 | { | |
37 | if ((addr >= (unsigned long)©_user_memcpy) && | |
38 | (addr <= (unsigned long)©_user_memcpy_end)) | |
39 | return &__copy_user_fixup_ex; | |
40 | ||
41 | return NULL; | |
42 | } | |
43 | ||
a94c33dd TM |
44 | static 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 | ||
1da177e4 LT |
57 | /* Simple binary search */ |
58 | const struct exception_table_entry * | |
a94c33dd TM |
59 | search_extable(const struct exception_table_entry *base, |
60 | const size_t num, | |
1da177e4 LT |
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 | ||
a94c33dd TM |
69 | return bsearch(&value, base, num, |
70 | sizeof(struct exception_table_entry), cmp_ex_search); | |
1da177e4 LT |
71 | } |
72 | ||
73 | int 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 | } |