1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 1999 Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se>
4 *
5 * (C) Copyright 2000
6 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
7 */
8 #include <common.h>
9
10 /*
11 * The exception table consists of pairs of addresses: the first is the
12 * address of an instruction that is allowed to fault, and the second is
13 * the address at which the program should continue. No registers are
14 * modified, so it is entirely up to the continuation code to figure out
15 * what to do.
16 *
17 * All the routines below use bits of fixup code that are out of line
18 * with the main instruction path. This means when everything is well,
19 * we don't even have to jump over them. Further, they do not intrude
20 * on our cache or tlb entries.
21 */
22
23 struct exception_table_entry
24 {
25 unsigned long insn, fixup;
26 };
27
28 extern const struct exception_table_entry __start___ex_table[];
29 extern const struct exception_table_entry __stop___ex_table[];
30
31 static inline unsigned long
search_one_table(const struct exception_table_entry * first,const struct exception_table_entry * last,unsigned long value)32 search_one_table(const struct exception_table_entry *first,
33 const struct exception_table_entry *last,
34 unsigned long value)
35 {
36 long diff;
37 while (first <= last) {
38 diff = first->insn - value;
39 if (diff == 0)
40 return first->fixup;
41 first++;
42 }
43
44 return 0;
45 }
46
47 unsigned long
search_exception_table(unsigned long addr)48 search_exception_table(unsigned long addr)
49 {
50 unsigned long ret;
51
52 /* There is only the kernel to search. */
53 ret = search_one_table(__start___ex_table, __stop___ex_table-1, addr);
54 /* if the serial port does not hang in exception, printf can be used */
55 #if !defined(CONFIG_SYS_SERIAL_HANG_IN_EXCEPTION)
56 debug("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret);
57 #endif
58 if (ret) return ret;
59
60 return 0;
61 }
62