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/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 int __kernel_text_address(unsigned long addr)
  76 {
  77         if (core_kernel_text(addr))
  78                 return 1;
  79         if (is_module_text_address(addr))
  80                 return 1;
  81         /*
  82          * There might be init symbols in saved stacktraces.
  83          * Give those symbols a chance to be printed in
  84          * backtraces (such as lockdep traces).
  85          *
  86          * Since we are after the module-symbols check, there's
  87          * no danger of address overlap:
  88          */
  89         if (init_kernel_text(addr))
  90                 return 1;
  91         return 0;
  92 }
  93
  94 int kernel_text_address(unsigned long addr)
  95 {
  96         if (core_kernel_text(addr))
  97                 return 1;
  98         return is_module_text_address(addr);
  99 }
 100
 101 /*
 102  * On some architectures (PPC64, IA64) function pointers
 103  * are actually only tokens to some data that then holds the
 104  * real function address. As a result, to find if a function
 105  * pointer is part of the kernel text, we need to do some
 106  * special dereferencing first.
 107  */
 108 int func_ptr_is_kernel_text(void *ptr)
 109 {
 110         unsigned long addr;
 111         addr = (unsigned long) dereference_function_descriptor(ptr);
 112         if (core_kernel_text(addr))
 113                 return 1;
 114         return is_module_text_address(addr);
 115 }