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 /**
  76  * core_kernel_data - tell if addr points to kernel data
  77  * @addr: address to test
  78  *
  79  * Returns true if @addr passed in is from the core kernel data
  80  * section.
  81  *
  82  * Note: On some archs it may return true for core RODATA, and false
  83  *  for others. But will always be true for core RW data.
  84  */
  85 int core_kernel_data(unsigned long addr)
  86 {
  87         if (addr >= (unsigned long)_sdata &&
  88             addr < (unsigned long)_edata)
  89                 return 1;
  90         return 0;
  91 }
  92
  93 int __kernel_text_address(unsigned long addr)
  94 {
  95         if (core_kernel_text(addr))
  96                 return 1;
  97         if (is_module_text_address(addr))
  98                 return 1;
  99         /*
 100          * There might be init symbols in saved stacktraces.
 101          * Give those symbols a chance to be printed in
 102          * backtraces (such as lockdep traces).
 103          *
 104          * Since we are after the module-symbols check, there's
 105          * no danger of address overlap:
 106          */
 107         if (init_kernel_text(addr))
 108                 return 1;
 109         return 0;
 110 }
 111
 112 int kernel_text_address(unsigned long addr)
 113 {
 114         if (core_kernel_text(addr))
 115                 return 1;
 116         return is_module_text_address(addr);
 117 }
 118
 119 /*
 120  * On some architectures (PPC64, IA64) function pointers
 121  * are actually only tokens to some data that then holds the
 122  * real function address. As a result, to find if a function
 123  * pointer is part of the kernel text, we need to do some
 124  * special dereferencing first.
 125  */
 126 int func_ptr_is_kernel_text(void *ptr)
 127 {
 128         unsigned long addr;
 129         addr = (unsigned long) dereference_function_descriptor(ptr);
 130         if (core_kernel_text(addr))
 131                 return 1;
 132         return is_module_text_address(addr);
 133 }