Root/kernel/extable.c

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/* Sort the kernel's built-in exception table */
39void __init sort_main_extable(void)
40{
41    sort_extable(__start___ex_table, __stop___ex_table);
42}
43
44/* Given an address, look for it in the exception tables. */
45const struct exception_table_entry *search_exception_tables(unsigned long addr)
46{
47    const struct exception_table_entry *e;
48
49    e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
50    if (!e)
51        e = search_module_extables(addr);
52    return e;
53}
54
55static inline int init_kernel_text(unsigned long addr)
56{
57    if (addr >= (unsigned long)_sinittext &&
58        addr <= (unsigned long)_einittext)
59        return 1;
60    return 0;
61}
62
63int core_kernel_text(unsigned long addr)
64{
65    if (addr >= (unsigned long)_stext &&
66        addr <= (unsigned long)_etext)
67        return 1;
68
69    if (system_state == SYSTEM_BOOTING &&
70        init_kernel_text(addr))
71        return 1;
72    return 0;
73}
74
75/**
76 * core_kernel_data - tell if addr points to kernel data
77 * @addr: address to test
78 *
79 * Returns true if @addr passed in is from the core kernel data
80 * section.
81 *
82 * Note: On some archs it may return true for core RODATA, and false
83 * for others. But will always be true for core RW data.
84 */
85int core_kernel_data(unsigned long addr)
86{
87    if (addr >= (unsigned long)_sdata &&
88        addr < (unsigned long)_edata)
89        return 1;
90    return 0;
91}
92
93int __kernel_text_address(unsigned long addr)
94{
95    if (core_kernel_text(addr))
96        return 1;
97    if (is_module_text_address(addr))
98        return 1;
99    /*
100     * There might be init symbols in saved stacktraces.
101     * Give those symbols a chance to be printed in
102     * backtraces (such as lockdep traces).
103     *
104     * Since we are after the module-symbols check, there's
105     * no danger of address overlap:
106     */
107    if (init_kernel_text(addr))
108        return 1;
109    return 0;
110}
111
112int kernel_text_address(unsigned long addr)
113{
114    if (core_kernel_text(addr))
115        return 1;
116    return is_module_text_address(addr);
117}
118
119/*
120 * On some architectures (PPC64, IA64) function pointers
121 * are actually only tokens to some data that then holds the
122 * real function address. As a result, to find if a function
123 * pointer is part of the kernel text, we need to do some
124 * special dereferencing first.
125 */
126int func_ptr_is_kernel_text(void *ptr)
127{
128    unsigned long addr;
129    addr = (unsigned long) dereference_function_descriptor(ptr);
130    if (core_kernel_text(addr))
131        return 1;
132    return is_module_text_address(addr);
133}
134

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