Release 4.15 kernel/extable.c

/* 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.
 *
 * Note: Also protects SMP-alternatives modification on x86.
 *
 * 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);
	}
}

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Paul Mackerras
15
50.00%
1
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Borislav Petkov
7
23.33%
1
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Uwe Kleine-König
4
13.33%
1
25.00%
David Daney
4
13.33%
1
25.00%
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30
100.00%
4
100.00%

/* 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;
}

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Rusty Russell
35
76.09%
2
50.00%
Linus Torvalds
10
21.74%
1
25.00%
Thomas Meyer
1
2.17%
1
25.00%
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46
100.00%
4
100.00%



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

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Rusty Russell
25
71.43%
1
33.33%
Ingo Molnar
9
25.71%
1
33.33%
Helge Deller
1
2.86%
1
33.33%
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35
100.00%
3
100.00%



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;
}

Contributors
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CommitProp
Ingo Molnar
22
45.83%
1
14.29%
Andrew Morton
18
37.50%
1
14.29%
Rusty Russell
4
8.33%
2
28.57%
Thomas Gleixner
2
4.17%
1
14.29%
Marcin Nowakowski
1
2.08%
1
14.29%
Helge Deller
1
2.08%
1
14.29%
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48
100.00%
7
100.00%

/**
 * 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;
}

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Steven Rostedt
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int __kernel_text_address(unsigned long addr)
{
	if (kernel_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;
}

Contributors
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Tokens
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CommitProp
Ingo Molnar
13
39.39%
1
25.00%
Rusty Russell
12
36.36%
1
25.00%
Daniel Borkmann
7
21.21%
1
25.00%
Steven Rostedt
1
3.03%
1
25.00%
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33
100.00%
4
100.00%



int kernel_text_address(unsigned long addr)
{
	bool no_rcu;
	int ret = 1;

	if (core_kernel_text(addr))
		return 1;

	/*
         * If a stack dump happens while RCU is not watching, then
         * RCU needs to be notified that it requires to start
         * watching again. This can happen either by tracing that
         * triggers a stack trace, or a WARN() that happens during
         * coming back from idle, or cpu on or offlining.
         *
         * is_module_text_address() as well as the kprobe slots
         * and is_bpf_text_address() require RCU to be watching.
         */
	no_rcu = !rcu_is_watching();

	/* Treat this like an NMI as it can happen anywhere */
	if (no_rcu)
		rcu_nmi_enter();

	if (is_module_text_address(addr))
		goto out;
	if (is_ftrace_trampoline(addr))
		goto out;
	if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
		goto out;
	if (is_bpf_text_address(addr))
		goto out;
	ret = 0;
out:
	if (no_rcu)
		rcu_nmi_exit();

	return ret;
}

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Steven Rostedt
56
54.37%
2
25.00%
Rusty Russell
24
23.30%
3
37.50%
Masami Hiramatsu
16
15.53%
1
12.50%
Daniel Borkmann
5
4.85%
1
12.50%
Linus Torvalds
2
1.94%
1
12.50%
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103
100.00%
8
100.00%

/*
 * 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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Arjan van de Ven
39
97.50%
1
50.00%
Rusty Russell
1
2.50%
1
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40
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2
100.00%

Overall Contributors
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Tokens
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Rusty Russell
107
24.94%
7
20.59%
Steven Rostedt
91
21.21%
5
14.71%
Ingo Molnar
55
12.82%
2
5.88%
Arjan van de Ven
40
9.32%
1
2.94%
Linus Torvalds
28
6.53%
3
8.82%
Masami Hiramatsu
19
4.43%
1
2.94%
Paul Mackerras
18
4.20%
1
2.94%
Andrew Morton
18
4.20%
1
2.94%
Daniel Borkmann
15
3.50%
1
2.94%
David Daney
11
2.56%
1
2.94%
Borislav Petkov
7
1.63%
1
2.94%
Uwe Kleine-König
4
0.93%
1
2.94%
Frédéric Weisbecker
4
0.93%
1
2.94%
Paul Gortmaker
3
0.70%
1
2.94%
Helge Deller
2
0.47%
1
2.94%
Thomas Gleixner
2
0.47%
1
2.94%
Andi Kleen
1
0.23%
1
2.94%
Thomas Meyer
1
0.23%
1
2.94%
Marcin Nowakowski
1
0.23%
1
2.94%
Zhou Chengming
1
0.23%
1
2.94%
Dmitri Vorobiev
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1
2.94%
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Directory: kernel

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