linux/kernel/extable.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Rewritten by Rusty Russell, on the backs of many others...
   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.

*/
#include <linux/elf.h>
#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(…) …;

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 = …;

/* Sort the kernel's built-in exception table */
void __init sort_main_extable(void)
{ … }

/* Given an address, look for it in the kernel exception table */
const
struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
{ … }

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

int notrace core_kernel_text(unsigned long addr)
{ … }

int __kernel_text_address(unsigned long addr)
{ … }

int kernel_text_address(unsigned long addr)
{ … }

/*
 * On some architectures (PPC64, IA64, PARISC) 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.
 */
#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
void *dereference_function_descriptor(void *ptr)
{
	func_desc_t *desc = ptr;
	void *p;

	if (!get_kernel_nofault(p, (void *)&desc->addr))
		ptr = p;
	return ptr;
}
EXPORT_SYMBOL_GPL(dereference_function_descriptor);

void *dereference_kernel_function_descriptor(void *ptr)
{
	if (ptr < (void *)__start_opd || ptr >= (void *)__end_opd)
		return ptr;

	return dereference_function_descriptor(ptr);
}
#endif

int func_ptr_is_kernel_text(void *ptr)
{ … }