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 /* Cleared by build time tools if the table is already sorted. */
39 u32 __initdata main_extable_sort_needed = 1;
40
41 /* Sort the kernel's built-in exception table */
sort_main_extable(void)42 void __init sort_main_extable(void)
43 {
44 if (main_extable_sort_needed) {
45 pr_notice("Sorting __ex_table...\n");
46 sort_extable(__start___ex_table, __stop___ex_table);
47 }
48 }
49
50 /* Given an address, look for it in the exception tables. */
search_exception_tables(unsigned long addr)51 const struct exception_table_entry *search_exception_tables(unsigned long addr)
52 {
53 const struct exception_table_entry *e;
54
55 e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
56 if (!e)
57 e = search_module_extables(addr);
58 return e;
59 }
60
init_kernel_text(unsigned long addr)61 static inline int init_kernel_text(unsigned long addr)
62 {
63 if (addr >= (unsigned long)_sinittext &&
64 addr <= (unsigned long)_einittext)
65 return 1;
66 return 0;
67 }
68
core_kernel_text(unsigned long addr)69 int core_kernel_text(unsigned long addr)
70 {
71 if (addr >= (unsigned long)_stext &&
72 addr <= (unsigned long)_etext)
73 return 1;
74
75 if (system_state == SYSTEM_BOOTING &&
76 init_kernel_text(addr))
77 return 1;
78 return 0;
79 }
80
81 /**
82 * core_kernel_data - tell if addr points to kernel data
83 * @addr: address to test
84 *
85 * Returns true if @addr passed in is from the core kernel data
86 * section.
87 *
88 * Note: On some archs it may return true for core RODATA, and false
89 * for others. But will always be true for core RW data.
90 */
core_kernel_data(unsigned long addr)91 int core_kernel_data(unsigned long addr)
92 {
93 if (addr >= (unsigned long)_sdata &&
94 addr < (unsigned long)_edata)
95 return 1;
96 return 0;
97 }
98
__kernel_text_address(unsigned long addr)99 int __kernel_text_address(unsigned long addr)
100 {
101 if (core_kernel_text(addr))
102 return 1;
103 if (is_module_text_address(addr))
104 return 1;
105 /*
106 * There might be init symbols in saved stacktraces.
107 * Give those symbols a chance to be printed in
108 * backtraces (such as lockdep traces).
109 *
110 * Since we are after the module-symbols check, there's
111 * no danger of address overlap:
112 */
113 if (init_kernel_text(addr))
114 return 1;
115 return 0;
116 }
117
kernel_text_address(unsigned long addr)118 int kernel_text_address(unsigned long addr)
119 {
120 if (core_kernel_text(addr))
121 return 1;
122 return is_module_text_address(addr);
123 }
124
125 /*
126 * On some architectures (PPC64, IA64) function pointers
127 * are actually only tokens to some data that then holds the
128 * real function address. As a result, to find if a function
129 * pointer is part of the kernel text, we need to do some
130 * special dereferencing first.
131 */
func_ptr_is_kernel_text(void * ptr)132 int func_ptr_is_kernel_text(void *ptr)
133 {
134 unsigned long addr;
135 addr = (unsigned long) dereference_function_descriptor(ptr);
136 if (core_kernel_text(addr))
137 return 1;
138 return is_module_text_address(addr);
139 }
140