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1 | /* |
2 | * Copyright (C) 1999 Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se> | |
3 | * | |
4 | * (C) Copyright 2000 | |
5 | * Wolfgang Denk, DENX Software Engineering, wd@denx.de. | |
6 | * | |
7 | * See file CREDITS for list of people who contributed to this | |
8 | * project. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License as | |
12 | * published by the Free Software Foundation; either version 2 of | |
13 | * the License, or (at your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, | |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | * GNU General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public License | |
21 | * along with this program; if not, write to the Free Software | |
22 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, | |
23 | * MA 02111-1307 USA | |
24 | */ | |
25 | #include <common.h> | |
26 | ||
27 | /* | |
28 | * The exception table consists of pairs of addresses: the first is the | |
29 | * address of an instruction that is allowed to fault, and the second is | |
30 | * the address at which the program should continue. No registers are | |
31 | * modified, so it is entirely up to the continuation code to figure out | |
32 | * what to do. | |
33 | * | |
34 | * All the routines below use bits of fixup code that are out of line | |
35 | * with the main instruction path. This means when everything is well, | |
36 | * we don't even have to jump over them. Further, they do not intrude | |
37 | * on our cache or tlb entries. | |
38 | */ | |
39 | ||
40 | struct exception_table_entry { | |
41 | unsigned long insn, fixup; | |
42 | }; | |
43 | ||
44 | extern const struct exception_table_entry __start___ex_table[]; | |
45 | extern const struct exception_table_entry __stop___ex_table[]; | |
46 | ||
47 | static inline unsigned long | |
48 | search_one_table (const struct exception_table_entry *first, | |
49 | const struct exception_table_entry *last, | |
50 | unsigned long value) | |
51 | { | |
52 | while (first <= last) { | |
53 | const struct exception_table_entry *mid; | |
54 | long diff; | |
55 | ||
56 | mid = (last - first) / 2 + first; | |
57 | diff = mid->insn - value; | |
58 | if (diff == 0) | |
59 | return mid->fixup; | |
60 | else if (diff < 0) | |
61 | first = mid + 1; | |
62 | else | |
63 | last = mid - 1; | |
64 | } | |
65 | return 0; | |
66 | } | |
67 | ||
68 | int ex_tab_message = 1; | |
69 | ||
70 | unsigned long search_exception_table (unsigned long addr) | |
71 | { | |
72 | unsigned long ret; | |
73 | ||
74 | /* There is only the kernel to search. */ | |
75 | ret = search_one_table (__start___ex_table, __stop___ex_table - 1, | |
76 | addr); | |
77 | if (ex_tab_message) | |
78 | printf ("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret); | |
79 | if (ret) | |
80 | return ret; | |
81 | ||
82 | return 0; | |
83 | } |