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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Rewritten by Rusty Russell, on the backs of many others...
3 Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
4
5*/
6#include <linux/ftrace.h>
7#include <linux/memory.h>
8#include <linux/extable.h>
9#include <linux/module.h>
10#include <linux/mutex.h>
11#include <linux/init.h>
12#include <linux/kprobes.h>
13#include <linux/filter.h>
14
15#include <asm/sections.h>
16#include <linux/uaccess.h>
17
18/*
19 * mutex protecting text section modification (dynamic code patching).
20 * some users need to sleep (allocating memory...) while they hold this lock.
21 *
22 * Note: Also protects SMP-alternatives modification on x86.
23 *
24 * NOT exported to modules - patching kernel text is a really delicate matter.
25 */
26DEFINE_MUTEX(text_mutex);
27
28extern struct exception_table_entry __start___ex_table[];
29extern struct exception_table_entry __stop___ex_table[];
30
31/* Cleared by build time tools if the table is already sorted. */
32u32 __initdata __visible main_extable_sort_needed = 1;
33
34/* Sort the kernel's built-in exception table */
35void __init sort_main_extable(void)
36{
37 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
38 pr_notice("Sorting __ex_table...\n");
39 sort_extable(__start___ex_table, __stop___ex_table);
40 }
41}
42
43/* Given an address, look for it in the kernel exception table */
44const
45struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
46{
47 return search_extable(__start___ex_table,
48 __stop___ex_table - __start___ex_table, addr);
49}
50
51/* Given an address, look for it in the exception tables. */
52const struct exception_table_entry *search_exception_tables(unsigned long addr)
53{
54 const struct exception_table_entry *e;
55
56 e = search_kernel_exception_table(addr);
57 if (!e)
58 e = search_module_extables(addr);
59 return e;
60}
61
62int init_kernel_text(unsigned long addr)
63{
64 if (addr >= (unsigned long)_sinittext &&
65 addr < (unsigned long)_einittext)
66 return 1;
67 return 0;
68}
69
70int notrace core_kernel_text(unsigned long addr)
71{
72 if (addr >= (unsigned long)_stext &&
73 addr < (unsigned long)_etext)
74 return 1;
75
76 if (system_state < SYSTEM_RUNNING &&
77 init_kernel_text(addr))
78 return 1;
79 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 */
92int core_kernel_data(unsigned long addr)
93{
94 if (addr >= (unsigned long)_sdata &&
95 addr < (unsigned long)_edata)
96 return 1;
97 return 0;
98}
99
100int __kernel_text_address(unsigned long addr)
101{
102 if (kernel_text_address(addr))
103 return 1;
104 /*
105 * There might be init symbols in saved stacktraces.
106 * Give those symbols a chance to be printed in
107 * backtraces (such as lockdep traces).
108 *
109 * Since we are after the module-symbols check, there's
110 * no danger of address overlap:
111 */
112 if (init_kernel_text(addr))
113 return 1;
114 return 0;
115}
116
117int kernel_text_address(unsigned long addr)
118{
119 bool no_rcu;
120 int ret = 1;
121
122 if (core_kernel_text(addr))
123 return 1;
124
125 /*
126 * If a stack dump happens while RCU is not watching, then
127 * RCU needs to be notified that it requires to start
128 * watching again. This can happen either by tracing that
129 * triggers a stack trace, or a WARN() that happens during
130 * coming back from idle, or cpu on or offlining.
131 *
132 * is_module_text_address() as well as the kprobe slots
133 * and is_bpf_text_address() require RCU to be watching.
134 */
135 no_rcu = !rcu_is_watching();
136
137 /* Treat this like an NMI as it can happen anywhere */
138 if (no_rcu)
139 rcu_nmi_enter();
140
141 if (is_module_text_address(addr))
142 goto out;
143 if (is_ftrace_trampoline(addr))
144 goto out;
145 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
146 goto out;
147 if (is_bpf_text_address(addr))
148 goto out;
149 ret = 0;
150out:
151 if (no_rcu)
152 rcu_nmi_exit();
153
154 return ret;
155}
156
157/*
158 * On some architectures (PPC64, IA64) function pointers
159 * are actually only tokens to some data that then holds the
160 * real function address. As a result, to find if a function
161 * pointer is part of the kernel text, we need to do some
162 * special dereferencing first.
163 */
164int func_ptr_is_kernel_text(void *ptr)
165{
166 unsigned long addr;
167 addr = (unsigned long) dereference_function_descriptor(ptr);
168 if (core_kernel_text(addr))
169 return 1;
170 return is_module_text_address(addr);
171}
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 <linux/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 if (is_ftrace_trampoline(addr))
106 return 1;
107 /*
108 * There might be init symbols in saved stacktraces.
109 * Give those symbols a chance to be printed in
110 * backtraces (such as lockdep traces).
111 *
112 * Since we are after the module-symbols check, there's
113 * no danger of address overlap:
114 */
115 if (init_kernel_text(addr))
116 return 1;
117 return 0;
118}
119
120int kernel_text_address(unsigned long addr)
121{
122 if (core_kernel_text(addr))
123 return 1;
124 if (is_module_text_address(addr))
125 return 1;
126 return is_ftrace_trampoline(addr);
127}
128
129/*
130 * On some architectures (PPC64, IA64) function pointers
131 * are actually only tokens to some data that then holds the
132 * real function address. As a result, to find if a function
133 * pointer is part of the kernel text, we need to do some
134 * special dereferencing first.
135 */
136int func_ptr_is_kernel_text(void *ptr)
137{
138 unsigned long addr;
139 addr = (unsigned long) dereference_function_descriptor(ptr);
140 if (core_kernel_text(addr))
141 return 1;
142 return is_module_text_address(addr);
143}