1 /* Rewritten by Rusty Russell, on the backs of many others...
2 Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
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.
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.
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
18 #include <linux/ftrace.h>
19 #include <linux/memory.h>
20 #include <linux/extable.h>
21 #include <linux/module.h>
22 #include <linux/mutex.h>
23 #include <linux/init.h>
24 #include <linux/kprobes.h>
25 #include <linux/filter.h>
27 #include <asm/sections.h>
28 #include <linux/uaccess.h>
31 * mutex protecting text section modification (dynamic code patching).
32 * some users need to sleep (allocating memory...) while they hold this lock.
34 * NOT exported to modules - patching kernel text is a really delicate matter.
36 DEFINE_MUTEX(text_mutex);
38 extern struct exception_table_entry __start___ex_table[];
39 extern struct exception_table_entry __stop___ex_table[];
41 /* Cleared by build time tools if the table is already sorted. */
42 u32 __initdata __visible main_extable_sort_needed = 1;
44 /* Sort the kernel's built-in exception table */
45 void __init sort_main_extable(void)
47 if (main_extable_sort_needed &&
48 &__stop___ex_table > &__start___ex_table) {
49 pr_notice("Sorting __ex_table...\n");
50 sort_extable(__start___ex_table, __stop___ex_table);
54 /* Given an address, look for it in the exception tables. */
55 const struct exception_table_entry *search_exception_tables(unsigned long addr)
57 const struct exception_table_entry *e;
59 e = search_extable(__start___ex_table,
60 __stop___ex_table - __start___ex_table, addr);
62 e = search_module_extables(addr);
66 static inline int init_kernel_text(unsigned long addr)
68 if (addr >= (unsigned long)_sinittext &&
69 addr < (unsigned long)_einittext)
74 int notrace core_kernel_text(unsigned long addr)
76 if (addr >= (unsigned long)_stext &&
77 addr < (unsigned long)_etext)
80 if (system_state < SYSTEM_RUNNING &&
81 init_kernel_text(addr))
87 * core_kernel_data - tell if addr points to kernel data
88 * @addr: address to test
90 * Returns true if @addr passed in is from the core kernel data
93 * Note: On some archs it may return true for core RODATA, and false
94 * for others. But will always be true for core RW data.
96 int core_kernel_data(unsigned long addr)
98 if (addr >= (unsigned long)_sdata &&
99 addr < (unsigned long)_edata)
104 int __kernel_text_address(unsigned long addr)
106 if (kernel_text_address(addr))
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).
113 * Since we are after the module-symbols check, there's
114 * no danger of address overlap:
116 if (init_kernel_text(addr))
121 int kernel_text_address(unsigned long addr)
126 if (core_kernel_text(addr))
130 * If a stack dump happens while RCU is not watching, then
131 * RCU needs to be notified that it requires to start
132 * watching again. This can happen either by tracing that
133 * triggers a stack trace, or a WARN() that happens during
134 * coming back from idle, or cpu on or offlining.
136 * is_module_text_address() as well as the kprobe slots
137 * and is_bpf_text_address() require RCU to be watching.
139 no_rcu = !rcu_is_watching();
141 /* Treat this like an NMI as it can happen anywhere */
145 if (is_module_text_address(addr))
147 if (is_ftrace_trampoline(addr))
149 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
151 if (is_bpf_text_address(addr))
162 * On some architectures (PPC64, IA64) function pointers
163 * are actually only tokens to some data that then holds the
164 * real function address. As a result, to find if a function
165 * pointer is part of the kernel text, we need to do some
166 * special dereferencing first.
168 int func_ptr_is_kernel_text(void *ptr)
171 addr = (unsigned long) dereference_function_descriptor(ptr);
172 if (core_kernel_text(addr))
174 return is_module_text_address(addr);