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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.
 * 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);
/* 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);
		e = search_module_extables(addr);
int init_kernel_text(unsigned long addr)
	if (addr >= (unsigned long)_sinittext &&
	    addr < (unsigned long)_einittext)
		return 1;
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;
 * 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;
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;
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;
	if (no_rcu)
		rcu_nmi_exit();
	return ret;
 * 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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