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[mirror_ubuntu-artful-kernel.git] / kernel / extable.c
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1da177e4
LT
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*/
505f2b97 18#include <linux/ftrace.h>
f80d2d77 19#include <linux/memory.h>
8a293be0 20#include <linux/extable.h>
1da177e4 21#include <linux/module.h>
505f2b97 22#include <linux/mutex.h>
1da177e4 23#include <linux/init.h>
5b485629 24#include <linux/kprobes.h>
74451e66 25#include <linux/filter.h>
505f2b97 26
1da177e4 27#include <asm/sections.h>
7c0f6ba6 28#include <linux/uaccess.h>
505f2b97
IM
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 */
36DEFINE_MUTEX(text_mutex);
1da177e4
LT
37
38extern struct exception_table_entry __start___ex_table[];
39extern struct exception_table_entry __stop___ex_table[];
40
d219e2e8 41/* Cleared by build time tools if the table is already sorted. */
00b71030 42u32 __initdata __visible main_extable_sort_needed = 1;
d219e2e8 43
1da177e4
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44/* Sort the kernel's built-in exception table */
45void __init sort_main_extable(void)
46{
e656a634 47 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
bec1b9e7 48 pr_notice("Sorting __ex_table...\n");
d219e2e8 49 sort_extable(__start___ex_table, __stop___ex_table);
bec1b9e7 50 }
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51}
52
53/* Given an address, look for it in the exception tables. */
54const 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
4a44bac1
IM
64static inline int init_kernel_text(unsigned long addr)
65{
66 if (addr >= (unsigned long)_sinittext &&
5ecbe3c3 67 addr < (unsigned long)_einittext)
4a44bac1
IM
68 return 1;
69 return 0;
70}
71
c0d80dda 72int notrace core_kernel_text(unsigned long addr)
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73{
74 if (addr >= (unsigned long)_stext &&
5ecbe3c3 75 addr < (unsigned long)_etext)
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76 return 1;
77
0594729c 78 if (system_state < SYSTEM_RUNNING &&
4a44bac1 79 init_kernel_text(addr))
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LT
80 return 1;
81 return 0;
82}
83
a2d063ac
SR
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 */
cdbe61bf
SR
94int core_kernel_data(unsigned long addr)
95{
a2d063ac 96 if (addr >= (unsigned long)_sdata &&
cdbe61bf
SR
97 addr < (unsigned long)_edata)
98 return 1;
99 return 0;
100}
101
3861a17b 102int __kernel_text_address(unsigned long addr)
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103{
104 if (core_kernel_text(addr))
105 return 1;
cab4e4c4 106 if (is_module_text_address(addr))
4a44bac1 107 return 1;
aec0be2d
SRRH
108 if (is_ftrace_trampoline(addr))
109 return 1;
5b485629
MH
110 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
111 return 1;
74451e66
DB
112 if (is_bpf_text_address(addr))
113 return 1;
4a44bac1
IM
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;
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LT
125}
126
127int kernel_text_address(unsigned long addr)
128{
129 if (core_kernel_text(addr))
130 return 1;
aec0be2d
SRRH
131 if (is_module_text_address(addr))
132 return 1;
5b485629
MH
133 if (is_ftrace_trampoline(addr))
134 return 1;
135 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
136 return 1;
74451e66
DB
137 if (is_bpf_text_address(addr))
138 return 1;
5b485629 139 return 0;
1da177e4 140}
ab7476cf
AV
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 */
149int 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;
a6e6abd5 155 return is_module_text_address(addr);
ab7476cf 156}