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 int core_kernel_text(unsigned long addr) 56 { 57 if (addr >= (unsigned long)_stext && 58 addr <= (unsigned long)_etext) 59 return 1; 60 61 if (system_state == SYSTEM_BOOTING && 62 addr >= (unsigned long)_sinittext && 63 addr <= (unsigned long)_einittext) 64 return 1; 65 return 0; 66 } 67 68 int __kernel_text_address(unsigned long addr) 69 { 70 if (core_kernel_text(addr)) 71 return 1; 72 return __module_text_address(addr) != NULL; 73 } 74 75 int kernel_text_address(unsigned long addr) 76 { 77 if (core_kernel_text(addr)) 78 return 1; 79 return module_text_address(addr) != NULL; 80 } 81 82 /* 83 * On some architectures (PPC64, IA64) function pointers 84 * are actually only tokens to some data that then holds the 85 * real function address. As a result, to find if a function 86 * pointer is part of the kernel text, we need to do some 87 * special dereferencing first. 88 */ 89 int func_ptr_is_kernel_text(void *ptr) 90 { 91 unsigned long addr; 92 addr = (unsigned long) dereference_function_descriptor(ptr); 93 if (core_kernel_text(addr)) 94 return 1; 95 return module_text_address(addr) != NULL; 96 } 97