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[mirror_ubuntu-bionic-kernel.git] / kernel / extable.c
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/extable.h>
21 #include <linux/module.h>
22 #include <linux/mutex.h>
23 #include <linux/init.h>
24 #include <linux/kprobes.h>
25 #include <linux/filter.h>
26
27 #include <asm/sections.h>
28 #include <linux/uaccess.h>
29
30 /*
31 * mutex protecting text section modification (dynamic code patching).
32 * some users need to sleep (allocating memory...) while they hold this lock.
33 *
34 * NOT exported to modules - patching kernel text is a really delicate matter.
35 */
36 DEFINE_MUTEX(text_mutex);
37
38 extern struct exception_table_entry __start___ex_table[];
39 extern struct exception_table_entry __stop___ex_table[];
40
41 /* Cleared by build time tools if the table is already sorted. */
42 u32 __initdata __visible main_extable_sort_needed = 1;
43
44 /* Sort the kernel's built-in exception table */
45 void __init sort_main_extable(void)
46 {
47 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
48 pr_notice("Sorting __ex_table...\n");
49 sort_extable(__start___ex_table, __stop___ex_table);
50 }
51 }
52
53 /* Given an address, look for it in the exception tables. */
54 const struct exception_table_entry *search_exception_tables(unsigned long addr)
55 {
56 const struct exception_table_entry *e;
57
58 e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
59 if (!e)
60 e = search_module_extables(addr);
61 return e;
62 }
63
64 static inline int init_kernel_text(unsigned long addr)
65 {
66 if (addr >= (unsigned long)_sinittext &&
67 addr < (unsigned long)_einittext)
68 return 1;
69 return 0;
70 }
71
72 int core_kernel_text(unsigned long addr)
73 {
74 if (addr >= (unsigned long)_stext &&
75 addr < (unsigned long)_etext)
76 return 1;
77
78 if (system_state == SYSTEM_BOOTING &&
79 init_kernel_text(addr))
80 return 1;
81 return 0;
82 }
83
84 /**
85 * core_kernel_data - tell if addr points to kernel data
86 * @addr: address to test
87 *
88 * Returns true if @addr passed in is from the core kernel data
89 * section.
90 *
91 * Note: On some archs it may return true for core RODATA, and false
92 * for others. But will always be true for core RW data.
93 */
94 int core_kernel_data(unsigned long addr)
95 {
96 if (addr >= (unsigned long)_sdata &&
97 addr < (unsigned long)_edata)
98 return 1;
99 return 0;
100 }
101
102 int __kernel_text_address(unsigned long addr)
103 {
104 if (core_kernel_text(addr))
105 return 1;
106 if (is_module_text_address(addr))
107 return 1;
108 if (is_ftrace_trampoline(addr))
109 return 1;
110 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
111 return 1;
112 if (is_bpf_text_address(addr))
113 return 1;
114 /*
115 * There might be init symbols in saved stacktraces.
116 * Give those symbols a chance to be printed in
117 * backtraces (such as lockdep traces).
118 *
119 * Since we are after the module-symbols check, there's
120 * no danger of address overlap:
121 */
122 if (init_kernel_text(addr))
123 return 1;
124 return 0;
125 }
126
127 int kernel_text_address(unsigned long addr)
128 {
129 if (core_kernel_text(addr))
130 return 1;
131 if (is_module_text_address(addr))
132 return 1;
133 if (is_ftrace_trampoline(addr))
134 return 1;
135 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
136 return 1;
137 if (is_bpf_text_address(addr))
138 return 1;
139 return 0;
140 }
141
142 /*
143 * On some architectures (PPC64, IA64) function pointers
144 * are actually only tokens to some data that then holds the
145 * real function address. As a result, to find if a function
146 * pointer is part of the kernel text, we need to do some
147 * special dereferencing first.
148 */
149 int func_ptr_is_kernel_text(void *ptr)
150 {
151 unsigned long addr;
152 addr = (unsigned long) dereference_function_descriptor(ptr);
153 if (core_kernel_text(addr))
154 return 1;
155 return is_module_text_address(addr);
156 }