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/ftrace.h> 22 #include <linux/mutex.h> 23 #include <linux/init.h> 24 25 #include <asm/sections.h> 26 #include <asm/uaccess.h> 27 28 /* 29 * mutex protecting text section modification (dynamic code patching). 30 * some users need to sleep (allocating memory...) while they hold this lock. 31 * 32 * NOT exported to modules - patching kernel text is a really delicate matter. 33 */ 34 DEFINE_MUTEX(text_mutex); 35 36 extern struct exception_table_entry __start___ex_table[]; 37 extern struct exception_table_entry __stop___ex_table[]; 38 39 /* Cleared by build time tools if the table is already sorted. */ 40 u32 __initdata __visible main_extable_sort_needed = 1; 41 42 /* Sort the kernel's built-in exception table */ 43 void __init sort_main_extable(void) 44 { 45 if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) { 46 pr_notice("Sorting __ex_table...\n"); 47 sort_extable(__start___ex_table, __stop___ex_table); 48 } 49 } 50 51 /* Given an address, look for it in the exception tables. */ 52 const struct exception_table_entry *search_exception_tables(unsigned long addr) 53 { 54 const struct exception_table_entry *e; 55 56 e = search_extable(__start___ex_table, __stop___ex_table-1, addr); 57 if (!e) 58 e = search_module_extables(addr); 59 return e; 60 } 61 62 static inline int init_kernel_text(unsigned long addr) 63 { 64 if (addr >= (unsigned long)_sinittext && 65 addr < (unsigned long)_einittext) 66 return 1; 67 return 0; 68 } 69 70 int core_kernel_text(unsigned long addr) 71 { 72 if (addr >= (unsigned long)_stext && 73 addr < (unsigned long)_etext) 74 return 1; 75 76 if (system_state == SYSTEM_BOOTING && 77 init_kernel_text(addr)) 78 return 1; 79 return 0; 80 } 81 82 /** 83 * core_kernel_data - tell if addr points to kernel data 84 * @addr: address to test 85 * 86 * Returns true if @addr passed in is from the core kernel data 87 * section. 88 * 89 * Note: On some archs it may return true for core RODATA, and false 90 * for others. But will always be true for core RW data. 91 */ 92 int core_kernel_data(unsigned long addr) 93 { 94 if (addr >= (unsigned long)_sdata && 95 addr < (unsigned long)_edata) 96 return 1; 97 return 0; 98 } 99 100 int __kernel_text_address(unsigned long addr) 101 { 102 if (core_kernel_text(addr)) 103 return 1; 104 if (is_module_text_address(addr)) 105 return 1; 106 if (is_ftrace_trampoline(addr)) 107 return 1; 108 /* 109 * There might be init symbols in saved stacktraces. 110 * Give those symbols a chance to be printed in 111 * backtraces (such as lockdep traces). 112 * 113 * Since we are after the module-symbols check, there's 114 * no danger of address overlap: 115 */ 116 if (init_kernel_text(addr)) 117 return 1; 118 return 0; 119 } 120 121 int kernel_text_address(unsigned long addr) 122 { 123 if (core_kernel_text(addr)) 124 return 1; 125 if (is_module_text_address(addr)) 126 return 1; 127 return is_ftrace_trampoline(addr); 128 } 129 130 /* 131 * On some architectures (PPC64, IA64) function pointers 132 * are actually only tokens to some data that then holds the 133 * real function address. As a result, to find if a function 134 * pointer is part of the kernel text, we need to do some 135 * special dereferencing first. 136 */ 137 int func_ptr_is_kernel_text(void *ptr) 138 { 139 unsigned long addr; 140 addr = (unsigned long) dereference_function_descriptor(ptr); 141 if (core_kernel_text(addr)) 142 return 1; 143 return is_module_text_address(addr); 144 } 145