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/ftrace.h>
22#include <linux/mutex.h>
23#include <linux/init.h>
24
25#include <asm/sections.h>
26#include <asm/uaccess.h>
27
28/*
29 * mutex protecting text section modification (dynamic code patching).
30 * some users need to sleep (allocating memory...) while they hold this lock.
31 *
32 * NOT exported to modules - patching kernel text is a really delicate matter.
33 */
34DEFINE_MUTEX(text_mutex);
35
36extern struct exception_table_entry __start___ex_table[];
37extern struct exception_table_entry __stop___ex_table[];
38
39/* Cleared by build time tools if the table is already sorted. */
40u32 __initdata __visible main_extable_sort_needed = 1;
41
42/* Sort the kernel's built-in exception table */
43void __init sort_main_extable(void)
44{
45	if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
46		pr_notice("Sorting __ex_table...\n");
47		sort_extable(__start___ex_table, __stop___ex_table);
48	}
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_extable(__start___ex_table, __stop___ex_table-1, addr);
57	if (!e)
58		e = search_module_extables(addr);
59	return e;
60}
61
62static inline int 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 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_BOOTING &&
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 (core_kernel_text(addr))
103		return 1;
104	if (is_module_text_address(addr))
105		return 1;
106	if (is_ftrace_trampoline(addr))
107		return 1;
108	/*
109	 * There might be init symbols in saved stacktraces.
110	 * Give those symbols a chance to be printed in
111	 * backtraces (such as lockdep traces).
112	 *
113	 * Since we are after the module-symbols check, there's
114	 * no danger of address overlap:
115	 */
116	if (init_kernel_text(addr))
117		return 1;
118	return 0;
119}
120
121int kernel_text_address(unsigned long addr)
122{
123	if (core_kernel_text(addr))
124		return 1;
125	if (is_module_text_address(addr))
126		return 1;
127	return is_ftrace_trampoline(addr);
128}
129
130/*
131 * On some architectures (PPC64, IA64) function pointers
132 * are actually only tokens to some data that then holds the
133 * real function address. As a result, to find if a function
134 * pointer is part of the kernel text, we need to do some
135 * special dereferencing first.
136 */
137int func_ptr_is_kernel_text(void *ptr)
138{
139	unsigned long addr;
140	addr = (unsigned long) dereference_function_descriptor(ptr);
141	if (core_kernel_text(addr))
142		return 1;
143	return is_module_text_address(addr);
144}
145