linux/kernel/extable.c
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   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
  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 */
  85int 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
  93int __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
 112int 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 */
 126int 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}
 134
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