Line data Source code
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/ftrace.h>
22 : #include <linux/mutex.h>
23 : #include <linux/init.h>
24 :
25 : #include <asm/sections.h>
26 : #include <asm/uaccess.h>
27 :
28 : /*
29 : * mutex protecting text section modification (dynamic code patching).
30 : * some users need to sleep (allocating memory...) while they hold this lock.
31 : *
32 : * NOT exported to modules - patching kernel text is a really delicate matter.
33 : */
34 : DEFINE_MUTEX(text_mutex);
35 :
36 : extern struct exception_table_entry __start___ex_table[];
37 : extern struct exception_table_entry __stop___ex_table[];
38 :
39 : /* Cleared by build time tools if the table is already sorted. */
40 : u32 __initdata __visible main_extable_sort_needed = 1;
41 :
42 : /* Sort the kernel's built-in exception table */
43 1 : void __init sort_main_extable(void)
44 : {
45 1 : if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
46 0 : pr_notice("Sorting __ex_table...\n");
47 0 : sort_extable(__start___ex_table, __stop___ex_table);
48 : }
49 1 : }
50 :
51 : /* Given an address, look for it in the exception tables. */
52 12 : const struct exception_table_entry *search_exception_tables(unsigned long addr)
53 : {
54 : const struct exception_table_entry *e;
55 :
56 12 : e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
57 12 : if (!e)
58 0 : e = search_module_extables(addr);
59 12 : return e;
60 : }
61 :
62 : static inline int init_kernel_text(unsigned long addr)
63 : {
64 0 : if (addr >= (unsigned long)_sinittext &&
65 0 : addr < (unsigned long)_einittext)
66 : return 1;
67 : return 0;
68 : }
69 :
70 12 : int core_kernel_text(unsigned long addr)
71 : {
72 48 : if (addr >= (unsigned long)_stext &&
73 24 : addr < (unsigned long)_etext)
74 : return 1;
75 :
76 0 : if (system_state == SYSTEM_BOOTING &&
77 : init_kernel_text(addr))
78 : return 1;
79 0 : return 0;
80 : }
81 :
82 : /**
83 : * core_kernel_data - tell if addr points to kernel data
84 : * @addr: address to test
85 : *
86 : * Returns true if @addr passed in is from the core kernel data
87 : * section.
88 : *
89 : * Note: On some archs it may return true for core RODATA, and false
90 : * for others. But will always be true for core RW data.
91 : */
92 0 : int core_kernel_data(unsigned long addr)
93 : {
94 0 : if (addr >= (unsigned long)_sdata &&
95 0 : addr < (unsigned long)_edata)
96 : return 1;
97 0 : return 0;
98 : }
99 :
100 0 : int __kernel_text_address(unsigned long addr)
101 : {
102 0 : if (core_kernel_text(addr))
103 : return 1;
104 0 : if (is_module_text_address(addr))
105 : return 1;
106 : if (is_ftrace_trampoline(addr))
107 : return 1;
108 : /*
109 : * There might be init symbols in saved stacktraces.
110 : * Give those symbols a chance to be printed in
111 : * backtraces (such as lockdep traces).
112 : *
113 : * Since we are after the module-symbols check, there's
114 : * no danger of address overlap:
115 : */
116 0 : if (init_kernel_text(addr))
117 : return 1;
118 0 : return 0;
119 : }
120 :
121 12 : int kernel_text_address(unsigned long addr)
122 : {
123 12 : if (core_kernel_text(addr))
124 : return 1;
125 0 : if (is_module_text_address(addr))
126 : return 1;
127 0 : return is_ftrace_trampoline(addr);
128 : }
129 :
130 : /*
131 : * On some architectures (PPC64, IA64) function pointers
132 : * are actually only tokens to some data that then holds the
133 : * real function address. As a result, to find if a function
134 : * pointer is part of the kernel text, we need to do some
135 : * special dereferencing first.
136 : */
137 0 : int func_ptr_is_kernel_text(void *ptr)
138 : {
139 : unsigned long addr;
140 0 : addr = (unsigned long) dereference_function_descriptor(ptr);
141 0 : if (core_kernel_text(addr))
142 : return 1;
143 0 : return is_module_text_address(addr);
144 : }
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