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	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}
144