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 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