aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/extable.c
blob: 7f8f263f85249a15ca8492fa5056c868262aa0f1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
/* Rewritten by Rusty Russell, on the backs of many others...
   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/ftrace.h>
#include <linux/memory.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/init.h>

#include <asm/sections.h>
#include <asm/uaccess.h>

/*
 * mutex protecting text section modification (dynamic code patching).
 * some users need to sleep (allocating memory...) while they hold this lock.
 *
 * NOT exported to modules - patching kernel text is a really delicate matter.
 */
DEFINE_MUTEX(text_mutex);

extern struct exception_table_entry __start___ex_table[];
extern struct exception_table_entry __stop___ex_table[];

/* Sort the kernel's built-in exception table */
void __init sort_main_extable(void)
{
	sort_extable(__start___ex_table, __stop___ex_table);
}

/* Given an address, look for it in the exception tables. */
const struct exception_table_entry *search_exception_tables(unsigned long addr)
{
	const struct exception_table_entry *e;

	e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
	if (!e)
		e = search_module_extables(addr);
	return e;
}

static inline int init_kernel_text(unsigned long addr)
{
	if (addr >= (unsigned long)_sinittext &&
	    addr <= (unsigned long)_einittext)
		return 1;
	return 0;
}

int core_kernel_text(unsigned long addr)
{
	if (addr >= (unsigned long)_stext &&
	    addr <= (unsigned long)_etext)
		return 1;

	if (system_state == SYSTEM_BOOTING &&
	    init_kernel_text(addr))
		return 1;
	return 0;
}

int __kernel_text_address(unsigned long addr)
{
	if (core_kernel_text(addr))
		return 1;
	if (is_module_text_address(addr))
		return 1;
	/*
	 * There might be init symbols in saved stacktraces.
	 * Give those symbols a chance to be printed in
	 * backtraces (such as lockdep traces).
	 *
	 * Since we are after the module-symbols check, there's
	 * no danger of address overlap:
	 */
	if (init_kernel_text(addr))
		return 1;
	return 0;
}

int kernel_text_address(unsigned long addr)
{
	if (core_kernel_text(addr))
		return 1;
	return is_module_text_address(addr);
}

/*
 * On some architectures (PPC64, IA64) function pointers
 * are actually only tokens to some data that then holds the
 * real function address. As a result, to find if a function
 * pointer is part of the kernel text, we need to do some
 * special dereferencing first.
 */
int func_ptr_is_kernel_text(void *ptr)
{
	unsigned long addr;
	addr = (unsigned long) dereference_function_descriptor(ptr);
	if (core_kernel_text(addr))
		return 1;
	return is_module_text_address(addr);
}