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 } 157