| 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/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> |
| 26 | |
| 27 | #include <asm/sections.h> |
| 28 | #include <linux/uaccess.h> |
| 29 | |
| 30 | /* |
| 31 | * mutex protecting text section modification (dynamic code patching). |
| 32 | * some users need to sleep (allocating memory...) while they hold this lock. |
| 33 | * |
| 34 | * NOT exported to modules - patching kernel text is a really delicate matter. |
| 35 | */ |
| 36 | DEFINE_MUTEX(text_mutex); |
| 37 | |
| 38 | extern struct exception_table_entry __start___ex_table[]; |
| 39 | extern struct exception_table_entry __stop___ex_table[]; |
| 40 | |
| 41 | /* Cleared by build time tools if the table is already sorted. */ |
| 42 | u32 __initdata __visible main_extable_sort_needed = 1; |
| 43 | |
| 44 | /* Sort the kernel's built-in exception table */ |
| 45 | void __init sort_main_extable(void) |
| 46 | { |
| 47 | if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) { |
| 48 | pr_notice("Sorting __ex_table...\n"); |
| 49 | sort_extable(__start___ex_table, __stop___ex_table); |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | /* Given an address, look for it in the exception tables. */ |
| 54 | const struct exception_table_entry *search_exception_tables(unsigned long addr) |
| 55 | { |
| 56 | const struct exception_table_entry *e; |
| 57 | |
| 58 | e = search_extable(__start___ex_table, __stop___ex_table-1, addr); |
| 59 | if (!e) |
| 60 | e = search_module_extables(addr); |
| 61 | return e; |
| 62 | } |
| 63 | |
| 64 | static inline int init_kernel_text(unsigned long addr) |
| 65 | { |
| 66 | if (addr >= (unsigned long)_sinittext && |
| 67 | addr < (unsigned long)_einittext) |
| 68 | return 1; |
| 69 | return 0; |
| 70 | } |
| 71 | |
| 72 | int core_kernel_text(unsigned long addr) |
| 73 | { |
| 74 | if (addr >= (unsigned long)_stext && |
| 75 | addr < (unsigned long)_etext) |
| 76 | return 1; |
| 77 | |
| 78 | if (system_state == SYSTEM_BOOTING && |
| 79 | init_kernel_text(addr)) |
| 80 | return 1; |
| 81 | return 0; |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * core_kernel_data - tell if addr points to kernel data |
| 86 | * @addr: address to test |
| 87 | * |
| 88 | * Returns true if @addr passed in is from the core kernel data |
| 89 | * section. |
| 90 | * |
| 91 | * Note: On some archs it may return true for core RODATA, and false |
| 92 | * for others. But will always be true for core RW data. |
| 93 | */ |
| 94 | int core_kernel_data(unsigned long addr) |
| 95 | { |
| 96 | if (addr >= (unsigned long)_sdata && |
| 97 | addr < (unsigned long)_edata) |
| 98 | return 1; |
| 99 | return 0; |
| 100 | } |
| 101 | |
| 102 | int __kernel_text_address(unsigned long addr) |
| 103 | { |
| 104 | if (core_kernel_text(addr)) |
| 105 | return 1; |
| 106 | if (is_module_text_address(addr)) |
| 107 | return 1; |
| 108 | if (is_ftrace_trampoline(addr)) |
| 109 | return 1; |
| 110 | if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) |
| 111 | return 1; |
| 112 | if (is_bpf_text_address(addr)) |
| 113 | return 1; |
| 114 | /* |
| 115 | * There might be init symbols in saved stacktraces. |
| 116 | * Give those symbols a chance to be printed in |
| 117 | * backtraces (such as lockdep traces). |
| 118 | * |
| 119 | * Since we are after the module-symbols check, there's |
| 120 | * no danger of address overlap: |
| 121 | */ |
| 122 | if (init_kernel_text(addr)) |
| 123 | return 1; |
| 124 | return 0; |
| 125 | } |
| 126 | |
| 127 | int kernel_text_address(unsigned long addr) |
| 128 | { |
| 129 | if (core_kernel_text(addr)) |
| 130 | return 1; |
| 131 | if (is_module_text_address(addr)) |
| 132 | return 1; |
| 133 | if (is_ftrace_trampoline(addr)) |
| 134 | return 1; |
| 135 | if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) |
| 136 | return 1; |
| 137 | if (is_bpf_text_address(addr)) |
| 138 | return 1; |
| 139 | return 0; |
| 140 | } |
| 141 | |
| 142 | /* |
| 143 | * On some architectures (PPC64, IA64) function pointers |
| 144 | * are actually only tokens to some data that then holds the |
| 145 | * real function address. As a result, to find if a function |
| 146 | * pointer is part of the kernel text, we need to do some |
| 147 | * special dereferencing first. |
| 148 | */ |
| 149 | int func_ptr_is_kernel_text(void *ptr) |
| 150 | { |
| 151 | unsigned long addr; |
| 152 | addr = (unsigned long) dereference_function_descriptor(ptr); |
| 153 | if (core_kernel_text(addr)) |
| 154 | return 1; |
| 155 | return is_module_text_address(addr); |
| 156 | } |