kernel/extable.c

   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/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/init.h>
  22
  23 #include <asm/sections.h>
  24 #include <asm/uaccess.h>
  25
  26 /*
  27  * mutex protecting text section modification (dynamic code patching).
  28  * some users need to sleep (allocating memory...) while they hold this lock.
  29  *
  30  * NOT exported to modules - patching kernel text is a really delicate matter.
  31  */
  32 DEFINE_MUTEX(text_mutex);
  33
  34 extern struct exception_table_entry __start___ex_table[];
  35 extern struct exception_table_entry __stop___ex_table[];
  36
  37 /* Sort the kernel's built-in exception table */
  38 void __init sort_main_extable(void)
  39 {
  40         sort_extable(__start___ex_table, __stop___ex_table);
  41 }
  42
  43 /* Given an address, look for it in the exception tables. */
  44 const struct exception_table_entry *search_exception_tables(unsigned long addr)
  45 {
  46         const struct exception_table_entry *e;
  47
  48         e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
  49         if (!e)
  50                 e = search_module_extables(addr);
  51         return e;
  52 }
  53
  54 int core_kernel_text(unsigned long addr)
  55 {
  56         if (addr >= (unsigned long)_stext &&
  57             addr <= (unsigned long)_etext)
  58                 return 1;
  59
  60         if (system_state == SYSTEM_BOOTING &&
  61             addr >= (unsigned long)_sinittext &&
  62             addr <= (unsigned long)_einittext)
  63                 return 1;
  64         return 0;
  65 }
  66
  67 int __kernel_text_address(unsigned long addr)
  68 {
  69         if (core_kernel_text(addr))
  70                 return 1;
  71         return __module_text_address(addr) != NULL;
  72 }
  73
  74 int kernel_text_address(unsigned long addr)
  75 {
  76         if (core_kernel_text(addr))
  77                 return 1;
  78         return module_text_address(addr) != NULL;
  79 }
  80
  81 /*
  82  * On some architectures (PPC64, IA64) function pointers
  83  * are actually only tokens to some data that then holds the
  84  * real function address. As a result, to find if a function
  85  * pointer is part of the kernel text, we need to do some
  86  * special dereferencing first.
  87  */
  88 int func_ptr_is_kernel_text(void *ptr)
  89 {
  90         unsigned long addr;
  91         addr = (unsigned long) dereference_function_descriptor(ptr);
  92         if (core_kernel_text(addr))
  93                 return 1;
  94         return module_text_address(addr) != NULL;
  95 }