LXR linux/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 */
  33DEFINE_MUTEX(text_mutex);
  34
  35extern struct exception_table_entry __start___ex_table[];
  36extern struct exception_table_entry __stop___ex_table[];
  37
  38/* Sort the kernel's built-in exception table */
  39void __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. */
  45const 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
  55static 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
  63int 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
  75int __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
  94int 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 */
 108int 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}
 116