linux/lib/extable.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
 *
 * Copyright (C) 2004 Paul Mackerras, IBM Corp.
 */

#include <linux/bsearch.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sort.h>
#include <linux/uaccess.h>
#include <linux/extable.h>

#ifndef ARCH_HAS_RELATIVE_EXTABLE
#define ex_to_insn …
#else
static inline unsigned long ex_to_insn(const struct exception_table_entry *x)
{ … }
#endif

#ifndef ARCH_HAS_RELATIVE_EXTABLE
#define swap_ex …
#else
static void swap_ex(void *a, void *b, int size)
{ … }
#endif /* ARCH_HAS_RELATIVE_EXTABLE */

/*
 * The exception table needs to be sorted so that the binary
 * search that we use to find entries in it works properly.
 * This is used both for the kernel exception table and for
 * the exception tables of modules that get loaded.
 */
static int cmp_ex_sort(const void *a, const void *b)
{ … }

void sort_extable(struct exception_table_entry *start,
		  struct exception_table_entry *finish)
{ … }

#ifdef CONFIG_MODULES
/*
 * If the exception table is sorted, any referring to the module init
 * will be at the beginning or the end.
 */
void trim_init_extable(struct module *m)
{ … }
#endif /* CONFIG_MODULES */

static int cmp_ex_search(const void *key, const void *elt)
{ … }

/*
 * Search one exception table for an entry corresponding to the
 * given instruction address, and return the address of the entry,
 * or NULL if none is found.
 * We use a binary search, and thus we assume that the table is
 * already sorted.
 */
const struct exception_table_entry *
search_extable(const struct exception_table_entry *base,
	       const size_t num,
	       unsigned long value)
{ … }