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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[];

/* Sort the kernel's built-in exception table */
void __init sort_main_extable(void)
{
sort_extable(__start___ex_table, __stop___ex_table);
}

/* 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;
}

/**
* core_kernel_data - tell if addr points to kernel data
* @addr: address to test
*
* Returns true if @addr passed in is from the core kernel data
* section.
*
* Note: On some archs it may return true for core RODATA, and false
* for others. But will always be true for core RW data.
*/
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);
}
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