xref: /openbmc/linux/kernel/extable.c (revision 7dd65feb)
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   */
33  DEFINE_MUTEX(text_mutex);
34  
35  extern struct exception_table_entry __start___ex_table[];
36  extern struct exception_table_entry __stop___ex_table[];
37  
38  /* Sort the kernel's built-in exception table */
39  void __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. */
45  const 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  
55  static 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  
63  int 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  int __kernel_text_address(unsigned long addr)
76  {
77  	if (core_kernel_text(addr))
78  		return 1;
79  	if (is_module_text_address(addr))
80  		return 1;
81  	/*
82  	 * There might be init symbols in saved stacktraces.
83  	 * Give those symbols a chance to be printed in
84  	 * backtraces (such as lockdep traces).
85  	 *
86  	 * Since we are after the module-symbols check, there's
87  	 * no danger of address overlap:
88  	 */
89  	if (init_kernel_text(addr))
90  		return 1;
91  	return 0;
92  }
93  
94  int kernel_text_address(unsigned long addr)
95  {
96  	if (core_kernel_text(addr))
97  		return 1;
98  	return is_module_text_address(addr);
99  }
100  
101  /*
102   * On some architectures (PPC64, IA64) function pointers
103   * are actually only tokens to some data that then holds the
104   * real function address. As a result, to find if a function
105   * pointer is part of the kernel text, we need to do some
106   * special dereferencing first.
107   */
108  int func_ptr_is_kernel_text(void *ptr)
109  {
110  	unsigned long addr;
111  	addr = (unsigned long) dereference_function_descriptor(ptr);
112  	if (core_kernel_text(addr))
113  		return 1;
114  	return is_module_text_address(addr);
115  }
116