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#include <log.h>
10
11/*
12 * The exception table consists of pairs of addresses: the first is the
13 * address of an instruction that is allowed to fault, and the second is
14 * the address at which the program should continue.  No registers are
15 * modified, so it is entirely up to the continuation code to figure out
16 * what to do.
17 *
18 * All the routines below use bits of fixup code that are out of line
19 * with the main instruction path.  This means when everything is well,
20 * we don't even have to jump over them.  Further, they do not intrude
21 * on our cache or tlb entries.
22 */
23
24struct exception_table_entry
25{
26	unsigned long insn, fixup;
27};
28
29extern const struct exception_table_entry __start___ex_table[];
30extern const struct exception_table_entry __stop___ex_table[];
31
32static inline unsigned long
33search_one_table(const struct exception_table_entry *first,
34		 const struct exception_table_entry *last,
35		 unsigned long value)
36{
37	long diff;
38	while (first <= last) {
39		diff = first->insn - value;
40		if (diff == 0)
41			return first->fixup;
42		first++;
43	}
44
45	return 0;
46}
47
48unsigned long
49search_exception_table(unsigned long addr)
50{
51	unsigned long ret;
52
53	/* There is only the kernel to search.  */
54	ret = search_one_table(__start___ex_table, __stop___ex_table-1, addr);
55	/* if the serial port does not hang in exception, printf can be used */
56#if !defined(CONFIG_SYS_SERIAL_HANG_IN_EXCEPTION)
57	debug("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret);
58#endif
59	if (ret) return ret;
60
61	return 0;
62}
63