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 */
33 DEFINE_MUTEX(text_mutex);
34
35 extern struct exception_table_entry __start___ex_table[];
36 extern struct exception_table_entry __stop___ex_table[];
37
38 /* Sort the kernel's built-in exception table */
39 void __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. */
45 const 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
55 static 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
63 int 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
75 int __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
94 int 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 */
108 int 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
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