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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 | */ |
1da177e4 LT |
13 | #include <linux/rwsem.h> |
14 | #include <linux/module.h> | |
7c0f6ba6 | 15 | #include <linux/uaccess.h> |
1da177e4 LT |
16 | |
17 | extern unsigned long copy_user_memcpy, copy_user_memcpy_end; | |
18 | extern void __copy_user_fixup(void); | |
19 | ||
20 | static const struct exception_table_entry __copy_user_fixup_ex = { | |
21 | .fixup = (unsigned long)&__copy_user_fixup, | |
22 | }; | |
23 | ||
a23ba435 PM |
24 | /* |
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 | */ | |
1da177e4 LT |
34 | static const struct exception_table_entry *check_exception_ranges(unsigned long addr) |
35 | { | |
36 | if ((addr >= (unsigned long)©_user_memcpy) && | |
37 | (addr <= (unsigned long)©_user_memcpy_end)) | |
38 | return &__copy_user_fixup_ex; | |
39 | ||
40 | return NULL; | |
41 | } | |
42 | ||
43 | /* Simple binary search */ | |
44 | const struct exception_table_entry * | |
45 | search_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 | ||
71 | int 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 | } |