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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/extable.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/init.h>

#include <linux/kprobes.h>

#include <linux/filter.h>

#include <asm/sections.h>

#include <linux/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 __visible main_extable_sort_needed = 1;

/* Sort the kernel's built-in exception table */

void __init sort_main_extable(void)

{

if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {

pr_notice("Sorting __ex_table...\n");

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 - __start___ex_table, 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 notrace core_kernel_text(unsigned long addr)

{

if (addr >= (unsigned long)_stext &&

addr < (unsigned long)_etext)

return 1;

if (system_state < SYSTEM_RUNNING &&

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;

if (is_ftrace_trampoline(addr))

return 1;

if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))

return 1;

if (is_bpf_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;

if (is_module_text_address(addr))

return 1;

if (is_ftrace_trampoline(addr))

return 1;

if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))

return 1;

if (is_bpf_text_address(addr))

return 1;

return 0;

}

/*

* 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);

}