1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Rewritten by Rusty Russell, on the backs of many others...
3 Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
6 #include <linux/ftrace.h>
7 #include <linux/memory.h>
8 #include <linux/extable.h>
9 #include <linux/module.h>
10 #include <linux/mutex.h>
11 #include <linux/init.h>
12 #include <linux/kprobes.h>
13 #include <linux/filter.h>
15 #include <asm/sections.h>
16 #include <linux/uaccess.h>
19 * mutex protecting text section modification (dynamic code patching).
20 * some users need to sleep (allocating memory...) while they hold this lock.
22 * Note: Also protects SMP-alternatives modification on x86.
24 * NOT exported to modules - patching kernel text is a really delicate matter.
26 DEFINE_MUTEX(text_mutex);
28 extern struct exception_table_entry __start___ex_table[];
29 extern struct exception_table_entry __stop___ex_table[];
31 /* Cleared by build time tools if the table is already sorted. */
32 u32 __initdata __visible main_extable_sort_needed = 1;
34 /* Sort the kernel's built-in exception table */
35 void __init sort_main_extable(void)
37 if (main_extable_sort_needed &&
38 &__stop___ex_table > &__start___ex_table) {
39 pr_notice("Sorting __ex_table...\n");
40 sort_extable(__start___ex_table, __stop___ex_table);
44 /* Given an address, look for it in the kernel exception table */
46 struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
48 return search_extable(__start___ex_table,
49 __stop___ex_table - __start___ex_table, addr);
52 /* Given an address, look for it in the exception tables. */
53 const struct exception_table_entry *search_exception_tables(unsigned long addr)
55 const struct exception_table_entry *e;
57 e = search_kernel_exception_table(addr);
59 e = search_module_extables(addr);
61 e = search_bpf_extables(addr);
65 int notrace core_kernel_text(unsigned long addr)
67 if (is_kernel_text(addr))
70 if (system_state < SYSTEM_FREEING_INITMEM &&
71 is_kernel_inittext(addr))
76 int __kernel_text_address(unsigned long addr)
78 if (kernel_text_address(addr))
81 * There might be init symbols in saved stacktraces.
82 * Give those symbols a chance to be printed in
83 * backtraces (such as lockdep traces).
85 * Since we are after the module-symbols check, there's
86 * no danger of address overlap:
88 if (is_kernel_inittext(addr))
93 int kernel_text_address(unsigned long addr)
98 if (core_kernel_text(addr))
102 * If a stack dump happens while RCU is not watching, then
103 * RCU needs to be notified that it requires to start
104 * watching again. This can happen either by tracing that
105 * triggers a stack trace, or a WARN() that happens during
106 * coming back from idle, or cpu on or offlining.
108 * is_module_text_address() as well as the kprobe slots,
109 * is_bpf_text_address() and is_bpf_image_address require
110 * RCU to be watching.
112 no_rcu = !rcu_is_watching();
114 /* Treat this like an NMI as it can happen anywhere */
118 if (is_module_text_address(addr))
120 if (is_ftrace_trampoline(addr))
122 if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
124 if (is_bpf_text_address(addr))
135 * On some architectures (PPC64, IA64) function pointers
136 * are actually only tokens to some data that then holds the
137 * real function address. As a result, to find if a function
138 * pointer is part of the kernel text, we need to do some
139 * special dereferencing first.
141 int func_ptr_is_kernel_text(void *ptr)
144 addr = (unsigned long) dereference_function_descriptor(ptr);
145 if (core_kernel_text(addr))
147 return is_module_text_address(addr);