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 /* Sort the kernel's built-in exception table */ 39 void __init sort_main_extable(void) 40 { 41 sort_extable(__start___ex_table, __stop___ex_table); 42 } 43 44 /* Given an address, look for it in the exception tables. */ 45 const struct exception_table_entry *search_exception_tables(unsigned long addr) 46 { 47 const struct exception_table_entry *e; 48 49 e = search_extable(__start___ex_table, __stop___ex_table-1, addr); 50 if (!e) 51 e = search_module_extables(addr); 52 return e; 53 } 54 55 static inline int init_kernel_text(unsigned long addr) 56 { 57 if (addr >= (unsigned long)_sinittext && 58 addr <= (unsigned long)_einittext) 59 return 1; 60 return 0; 61 } 62 63 int core_kernel_text(unsigned long addr) 64 { 65 if (addr >= (unsigned long)_stext && 66 addr <= (unsigned long)_etext) 67 return 1; 68 69 if (system_state == SYSTEM_BOOTING && 70 init_kernel_text(addr)) 71 return 1; 72 return 0; 73 } 74 75 /** 76 * core_kernel_data - tell if addr points to kernel data 77 * @addr: address to test 78 * 79 * Returns true if @addr passed in is from the core kernel data 80 * section. 81 * 82 * Note: On some archs it may return true for core RODATA, and false 83 * for others. But will always be true for core RW data. 84 */ 85 int core_kernel_data(unsigned long addr) 86 { 87 if (addr >= (unsigned long)_sdata && 88 addr < (unsigned long)_edata) 89 return 1; 90 return 0; 91 } 92 93 int __kernel_text_address(unsigned long addr) 94 { 95 if (core_kernel_text(addr)) 96 return 1; 97 if (is_module_text_address(addr)) 98 return 1; 99 /* 100 * There might be init symbols in saved stacktraces. 101 * Give those symbols a chance to be printed in 102 * backtraces (such as lockdep traces). 103 * 104 * Since we are after the module-symbols check, there's 105 * no danger of address overlap: 106 */ 107 if (init_kernel_text(addr)) 108 return 1; 109 return 0; 110 } 111 112 int kernel_text_address(unsigned long addr) 113 { 114 if (core_kernel_text(addr)) 115 return 1; 116 return is_module_text_address(addr); 117 } 118 119 /* 120 * On some architectures (PPC64, IA64) function pointers 121 * are actually only tokens to some data that then holds the 122 * real function address. As a result, to find if a function 123 * pointer is part of the kernel text, we need to do some 124 * special dereferencing first. 125 */ 126 int func_ptr_is_kernel_text(void *ptr) 127 { 128 unsigned long addr; 129 addr = (unsigned long) dereference_function_descriptor(ptr); 130 if (core_kernel_text(addr)) 131 return 1; 132 return is_module_text_address(addr); 133 } 134