extable.c

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/* Rewritten by Rusty Russell, on the backs of many others...
   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/ftrace.h>
#include <linux/memory.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/init.h>

#include <asm/sections.h>
#include <asm/uaccess.h>

/*
 * mutex protecting text section modification (dynamic code patching).
 * some users need to sleep (allocating memory...) while they hold this lock.
 *
 * NOT exported to modules - patching kernel text is a really delicate matter.
 */
DEFINE_MUTEX(text_mutex);

extern struct exception_table_entry __start___ex_table[];
extern struct exception_table_entry __stop___ex_table[];

/* Cleared by build time tools if the table is already sorted. */
u32 __initdata main_extable_sort_needed = 1;

/* Sort the kernel's built-in exception table */
void __init sort_main_extable(void)
{
    if (main_extable_sort_needed)
        sort_extable(__start___ex_table, __stop___ex_table);
    else
        pr_notice("__ex_table already sorted, skipping sort\n");
}

/* Given an address, look for it in the exception tables. */
const struct exception_table_entry *search_exception_tables(unsigned long addr)
{
    const struct exception_table_entry *e;

    e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
    if (!e)
        e = search_module_extables(addr);
    return e;
}

static inline int init_kernel_text(unsigned long addr)
{
    if (addr >= (unsigned long)_sinittext &&
        addr <= (unsigned long)_einittext)
        return 1;
    return 0;
}

int core_kernel_text(unsigned long addr)
{
    if (addr >= (unsigned long)_stext &&
        addr <= (unsigned long)_etext)
        return 1;

    if (system_state == SYSTEM_BOOTING &&
        init_kernel_text(addr))
        return 1;
    return 0;
}

int core_kernel_data(unsigned long addr)
{
    if (addr >= (unsigned long)_sdata &&
        addr < (unsigned long)_edata)
        return 1;
    return 0;
}

int __kernel_text_address(unsigned long addr)
{
    if (core_kernel_text(addr))
        return 1;
    if (is_module_text_address(addr))
        return 1;
    /*
     * There might be init symbols in saved stacktraces.
     * Give those symbols a chance to be printed in
     * backtraces (such as lockdep traces).
     *
     * Since we are after the module-symbols check, there's
     * no danger of address overlap:
     */
    if (init_kernel_text(addr))
        return 1;
    return 0;
}

int kernel_text_address(unsigned long addr)
{
    if (core_kernel_text(addr))
        return 1;
    return is_module_text_address(addr);
}

/*
 * On some architectures (PPC64, IA64) function pointers
 * are actually only tokens to some data that then holds the
 * real function address. As a result, to find if a function
 * pointer is part of the kernel text, we need to do some
 * special dereferencing first.
 */
int func_ptr_is_kernel_text(void *ptr)
{
    unsigned long addr;
    addr = (unsigned long) dereference_function_descriptor(ptr);
    if (core_kernel_text(addr))
        return 1;
    return is_module_text_address(addr);
}