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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* 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*/
Frederic Weisbecker8b96f012008-12-06 03:40:00 +010018#include <linux/ftrace.h>
Dmitri Vorobievf80d2d72009-03-22 19:11:10 +020019#include <linux/memory.h>
Ingo Molnar505f2b92009-03-20 11:05:04 +010020#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/init.h>
23
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <asm/sections.h>
Ingo Molnar505f2b92009-03-20 11:05:04 +010025#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);
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35extern struct exception_table_entry __start___ex_table[];
36extern struct exception_table_entry __stop___ex_table[];
37
David Daneyd219e2e2012-04-19 14:59:56 -070038/* Cleared by build time tools if the table is already sorted. */
Andi Kleen00b71032014-02-08 08:52:04 +010039u32 __initdata __visible main_extable_sort_needed = 1;
David Daneyd219e2e2012-04-19 14:59:56 -070040
Linus Torvalds1da177e2005-04-16 15:20:36 -070041/* Sort the kernel's built-in exception table */
42void __init sort_main_extable(void)
43{
Uwe Kleine-Könige656a632013-09-11 14:23:27 -070044 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
Borislav Petkovbec1b9e2013-04-15 12:51:49 +020045 pr_notice("Sorting __ex_table...\n");
David Daneyd219e2e2012-04-19 14:59:56 -070046 sort_extable(__start___ex_table, __stop___ex_table);
Borislav Petkovbec1b9e2013-04-15 12:51:49 +020047 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070048}
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
Ingo Molnar4a44bac2009-03-19 13:21:44 +010061static inline int init_kernel_text(unsigned long addr)
62{
63 if (addr >= (unsigned long)_sinittext &&
Helge Deller5ecbe3c2013-11-28 09:16:33 +010064 addr < (unsigned long)_einittext)
Ingo Molnar4a44bac2009-03-19 13:21:44 +010065 return 1;
66 return 0;
67}
68
Marcin Nowakowski717ce692017-07-06 15:35:31 -070069int notrace core_kernel_text(unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
71 if (addr >= (unsigned long)_stext &&
Helge Deller5ecbe3c2013-11-28 09:16:33 +010072 addr < (unsigned long)_etext)
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 return 1;
74
Rusty Russella2da4052008-01-29 17:13:17 -050075 if (system_state == SYSTEM_BOOTING &&
Ingo Molnar4a44bac2009-03-19 13:21:44 +010076 init_kernel_text(addr))
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 return 1;
78 return 0;
79}
80
Steven Rostedta2d063a2011-05-19 21:34:58 -040081/**
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 */
Steven Rostedtcdbe61b2011-05-05 21:14:55 -040091int core_kernel_data(unsigned long addr)
92{
Steven Rostedta2d063a2011-05-19 21:34:58 -040093 if (addr >= (unsigned long)_sdata &&
Steven Rostedtcdbe61b2011-05-05 21:14:55 -040094 addr < (unsigned long)_edata)
95 return 1;
96 return 0;
97}
98
Frederic Weisbecker3861a172009-02-08 00:04:02 +010099int __kernel_text_address(unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
101 if (core_kernel_text(addr))
102 return 1;
Linus Torvaldscab4e4c2009-04-05 10:30:21 -0700103 if (is_module_text_address(addr))
Ingo Molnar4a44bac2009-03-19 13:21:44 +0100104 return 1;
Steven Rostedt (Red Hat)aec0be22014-11-18 21:14:11 -0500105 if (is_ftrace_trampoline(addr))
106 return 1;
Ingo Molnar4a44bac2009-03-19 13:21:44 +0100107 /*
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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118}
119
120int kernel_text_address(unsigned long addr)
121{
122 if (core_kernel_text(addr))
123 return 1;
Steven Rostedt (Red Hat)aec0be22014-11-18 21:14:11 -0500124 if (is_module_text_address(addr))
125 return 1;
126 return is_ftrace_trampoline(addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
Arjan van de Venab7476c2008-08-15 15:29:38 -0700128
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;
Rusty Russella6e6abd2009-03-31 13:05:31 -0600142 return is_module_text_address(addr);
Arjan van de Venab7476c2008-08-15 15:29:38 -0700143}