1/* Rewritten by Rusty Russell, on the backs of many others...
2   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
3
4    This program is free software; you can redistribute it and/or modify
5    it under the terms of the GNU General Public License as published by
6    the Free Software Foundation; either version 2 of the License, or
7    (at your option) any later version.
8
9    This program is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12    GNU General Public License for more details.
13
14    You should have received a copy of the GNU General Public License
15    along with this program; if not, write to the Free Software
16    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17*/
18#include <linux/ftrace.h>
19#include <linux/memory.h>
20#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/init.h>
23
24#include <asm/sections.h>
25#include <asm/uaccess.h>
26
27/*
28 * mutex protecting text section modification (dynamic code patching).
29 * some users need to sleep (allocating memory...) while they hold this lock.
30 *
31 * NOT exported to modules - patching kernel text is a really delicate matter.
32 */
33DEFINE_MUTEX(text_mutex);
34
35extern struct exception_table_entry __start___ex_table[];
36extern struct exception_table_entry __stop___ex_table[];
37
38/* Sort the kernel's built-in exception table */
39void __init sort_main_extable(void)
40{
41	sort_extable(__start___ex_table, __stop___ex_table);
42}
43
44/* Given an address, look for it in the exception tables. */
45const struct exception_table_entry *search_exception_tables(unsigned long addr)
46{
47	const struct exception_table_entry *e;
48
49	e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
50	if (!e)
51		e = search_module_extables(addr);
52	return e;
53}
54
55static inline int init_kernel_text(unsigned long addr)
56{
57	if (addr >= (unsigned long)_sinittext &&
58	    addr <= (unsigned long)_einittext)
59		return 1;
60	return 0;
61}
62
63int core_kernel_text(unsigned long addr)
64{
65	if (addr >= (unsigned long)_stext &&
66	    addr <= (unsigned long)_etext)
67		return 1;
68
69	if (system_state == SYSTEM_BOOTING &&
70	    init_kernel_text(addr))
71		return 1;
72	return 0;
73}
74
75int __kernel_text_address(unsigned long addr)
76{
77	if (core_kernel_text(addr))
78		return 1;
79	if (is_module_text_address(addr))
80		return 1;
81	/*
82	 * There might be init symbols in saved stacktraces.
83	 * Give those symbols a chance to be printed in
84	 * backtraces (such as lockdep traces).
85	 *
86	 * Since we are after the module-symbols check, there's
87	 * no danger of address overlap:
88	 */
89	if (init_kernel_text(addr))
90		return 1;
91	return 0;
92}
93
94int kernel_text_address(unsigned long addr)
95{
96	if (core_kernel_text(addr))
97		return 1;
98	return is_module_text_address(addr);
99}
100
101/*
102 * On some architectures (PPC64, IA64) function pointers
103 * are actually only tokens to some data that then holds the
104 * real function address. As a result, to find if a function
105 * pointer is part of the kernel text, we need to do some
106 * special dereferencing first.
107 */
108int func_ptr_is_kernel_text(void *ptr)
109{
110	unsigned long addr;
111	addr = (unsigned long) dereference_function_descriptor(ptr);
112	if (core_kernel_text(addr))
113		return 1;
114	return is_module_text_address(addr);
115}
116