1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * kernel/configs.c
4 * Echo the kernel .config file used to build the kernel
5 *
6 * Copyright (C) 2002 Khalid Aziz <khalid_aziz@hp.com>
7 * Copyright (C) 2002 Randy Dunlap <rdunlap@xenotime.net>
8 * Copyright (C) 2002 Al Stone <ahs3@fc.hp.com>
9 * Copyright (C) 2002 Hewlett-Packard Company
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/proc_fs.h>
15#include <linux/seq_file.h>
16#include <linux/init.h>
17#include <linux/uaccess.h>
18
19/*
20 * "IKCFG_ST" and "IKCFG_ED" are used to extract the config data from
21 * a binary kernel image or a module. See scripts/extract-ikconfig.
22 */
23asm (
24"	.pushsection .rodata, \"a\"		\n"
25"	.ascii \"IKCFG_ST\"			\n"
26"	.global kernel_config_data		\n"
27"kernel_config_data:				\n"
28"	.incbin \"kernel/config_data.gz\"	\n"
29"	.global kernel_config_data_end		\n"
30"kernel_config_data_end:			\n"
31"	.ascii \"IKCFG_ED\"			\n"
32"	.popsection				\n"
33);
34
35#ifdef CONFIG_IKCONFIG_PROC
36
37extern char kernel_config_data;
38extern char kernel_config_data_end;
39
40static ssize_t
41ikconfig_read_current(struct file *file, char __user *buf,
42		      size_t len, loff_t * offset)
43{
44	return simple_read_from_buffer(buf, len, offset,
45				       &kernel_config_data,
46				       &kernel_config_data_end -
47				       &kernel_config_data);
48}
49
50static const struct proc_ops config_gz_proc_ops = {
51	.proc_read	= ikconfig_read_current,
52	.proc_lseek	= default_llseek,
53};
54
55static int __init ikconfig_init(void)
56{
57	struct proc_dir_entry *entry;
58
59	/* create the current config file */
60	entry = proc_create("config.gz", S_IFREG | S_IRUGO, NULL,
61			    &config_gz_proc_ops);
62	if (!entry)
63		return -ENOMEM;
64
65	proc_set_size(entry, &kernel_config_data_end - &kernel_config_data);
66
67	return 0;
68}
69
70static void __exit ikconfig_cleanup(void)
71{
72	remove_proc_entry("config.gz", NULL);
73}
74
75module_init(ikconfig_init);
76module_exit(ikconfig_cleanup);
77
78#endif /* CONFIG_IKCONFIG_PROC */
79
80MODULE_LICENSE("GPL");
81MODULE_AUTHOR("Randy Dunlap");
82MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");
83