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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 * Note: Also protects SMP-alternatives modification on x86.
35 *
36 * NOT exported to modules - patching kernel text is a really delicate matter.
37 */
38DEFINE_MUTEX(text_mutex);
39
40extern struct exception_table_entry __start___ex_table[];
41extern struct exception_table_entry __stop___ex_table[];
42
43/* Cleared by build time tools if the table is already sorted. */
44u32 __initdata __visible main_extable_sort_needed = 1;
45
46/* Sort the kernel's built-in exception table */
47void __init sort_main_extable(void)
48{
49 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
50 pr_notice("Sorting __ex_table...\n");
51 sort_extable(__start___ex_table, __stop___ex_table);
52 }
53}
54
55/* Given an address, look for it in the exception tables. */
56const struct exception_table_entry *search_exception_tables(unsigned long addr)
57{
58 const struct exception_table_entry *e;
59
60 e = search_extable(__start___ex_table,
61 __stop___ex_table - __start___ex_table, addr);
62 if (!e)
63 e = search_module_extables(addr);
64 return e;
65}
66
67int init_kernel_text(unsigned long addr)
68{
69 if (addr >= (unsigned long)_sinittext &&
70 addr < (unsigned long)_einittext)
71 return 1;
72 return 0;
73}
74
75int notrace core_kernel_text(unsigned long addr)
76{
77 if (addr >= (unsigned long)_stext &&
78 addr < (unsigned long)_etext)
79 return 1;
80
81 if (system_state < SYSTEM_RUNNING &&
82 init_kernel_text(addr))
83 return 1;
84 return 0;
85}
86
87/**
88 * core_kernel_data - tell if addr points to kernel data
89 * @addr: address to test
90 *
91 * Returns true if @addr passed in is from the core kernel data
92 * section.
93 *
94 * Note: On some archs it may return true for core RODATA, and false
95 * for others. But will always be true for core RW data.
96 */
97int core_kernel_data(unsigned long addr)
98{
99 if (addr >= (unsigned long)_sdata &&
100 addr < (unsigned long)_edata)
101 return 1;
102 return 0;
103}
104
105int __kernel_text_address(unsigned long addr)
106{
107 if (kernel_text_address(addr))
108 return 1;
109 /*
110 * There might be init symbols in saved stacktraces.
111 * Give those symbols a chance to be printed in
112 * backtraces (such as lockdep traces).
113 *
114 * Since we are after the module-symbols check, there's
115 * no danger of address overlap:
116 */
117 if (init_kernel_text(addr))
118 return 1;
119 return 0;
120}
121
122int kernel_text_address(unsigned long addr)
123{
124 bool no_rcu;
125 int ret = 1;
126
127 if (core_kernel_text(addr))
128 return 1;
129
130 /*
131 * If a stack dump happens while RCU is not watching, then
132 * RCU needs to be notified that it requires to start
133 * watching again. This can happen either by tracing that
134 * triggers a stack trace, or a WARN() that happens during
135 * coming back from idle, or cpu on or offlining.
136 *
137 * is_module_text_address() as well as the kprobe slots
138 * and is_bpf_text_address() require RCU to be watching.
139 */
140 no_rcu = !rcu_is_watching();
141
142 /* Treat this like an NMI as it can happen anywhere */
143 if (no_rcu)
144 rcu_nmi_enter();
145
146 if (is_module_text_address(addr))
147 goto out;
148 if (is_ftrace_trampoline(addr))
149 goto out;
150 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
151 goto out;
152 if (is_bpf_text_address(addr))
153 goto out;
154 ret = 0;
155out:
156 if (no_rcu)
157 rcu_nmi_exit();
158
159 return ret;
160}
161
162/*
163 * On some architectures (PPC64, IA64) function pointers
164 * are actually only tokens to some data that then holds the
165 * real function address. As a result, to find if a function
166 * pointer is part of the kernel text, we need to do some
167 * special dereferencing first.
168 */
169int func_ptr_is_kernel_text(void *ptr)
170{
171 unsigned long addr;
172 addr = (unsigned long) dereference_function_descriptor(ptr);
173 if (core_kernel_text(addr))
174 return 1;
175 return is_module_text_address(addr);
176}
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 */
33DEFINE_MUTEX(text_mutex);
34
35extern struct exception_table_entry __start___ex_table[];
36extern struct exception_table_entry __stop___ex_table[];
37
38/* Cleared by build time tools if the table is already sorted. */
39u32 __initdata __visible main_extable_sort_needed = 1;
40
41/* Sort the kernel's built-in exception table */
42void __init sort_main_extable(void)
43{
44 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
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. */
51const 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
61static 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
69int 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 */
91int 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
99int __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
118int 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 */
132int 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}