blob: 4f06fc34313fc4480c90199ddf3bc9b7e466b031
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 | /* Cleared by build time tools if the table is already sorted. */ |
39 | u32 __initdata __visible main_extable_sort_needed = 1; |
40 | |
41 | /* Sort the kernel's built-in exception table */ |
42 | void __init sort_main_extable(void) |
43 | { |
44 | if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) { |
45 | pr_notice("Sorting __ex_table...\n"); |
46 | sort_extable(__start___ex_table, __stop___ex_table); |
47 | } |
48 | } |
49 | |
50 | /* Given an address, look for it in the exception tables. */ |
51 | const 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 | |
61 | static inline int init_kernel_text(unsigned long addr) |
62 | { |
63 | if (addr >= (unsigned long)_sinittext && |
64 | addr < (unsigned long)_einittext) |
65 | return 1; |
66 | return 0; |
67 | } |
68 | |
69 | int notrace core_kernel_text(unsigned long addr) |
70 | { |
71 | if (addr >= (unsigned long)_stext && |
72 | addr < (unsigned long)_etext) |
73 | return 1; |
74 | |
75 | if (system_state == SYSTEM_BOOTING && |
76 | init_kernel_text(addr)) |
77 | return 1; |
78 | return 0; |
79 | } |
80 | |
81 | /** |
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 | */ |
91 | int core_kernel_data(unsigned long addr) |
92 | { |
93 | if (addr >= (unsigned long)_sdata && |
94 | addr < (unsigned long)_edata) |
95 | return 1; |
96 | return 0; |
97 | } |
98 | |
99 | int __kernel_text_address(unsigned long addr) |
100 | { |
101 | if (core_kernel_text(addr)) |
102 | return 1; |
103 | if (is_module_text_address(addr)) |
104 | return 1; |
105 | if (is_ftrace_trampoline(addr)) |
106 | return 1; |
107 | /* |
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; |
118 | } |
119 | |
120 | int kernel_text_address(unsigned long addr) |
121 | { |
122 | if (core_kernel_text(addr)) |
123 | return 1; |
124 | if (is_module_text_address(addr)) |
125 | return 1; |
126 | return is_ftrace_trampoline(addr); |
127 | } |
128 | |
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 | */ |
136 | int 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; |
142 | return is_module_text_address(addr); |
143 | } |
144 |