the-tree/kernel/configs.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * kernel/configs.c
0004  * Echo the kernel .config file used to build the kernel
0005  *
0006  * Copyright (C) 2002 Khalid Aziz <khalid_aziz@hp.com>
0007  * Copyright (C) 2002 Randy Dunlap <rdunlap@xenotime.net>
0008  * Copyright (C) 2002 Al Stone <ahs3@fc.hp.com>
0009  * Copyright (C) 2002 Hewlett-Packard Company
0010  */
0011
0012 #include <linux/kernel.h>
0013 #include <linux/module.h>
0014 #include <linux/proc_fs.h>
0015 #include <linux/seq_file.h>
0016 #include <linux/init.h>
0017 #include <linux/uaccess.h>
0018
0019 /*
0020  * "IKCFG_ST" and "IKCFG_ED" are used to extract the config data from
0021  * a binary kernel image or a module. See scripts/extract-ikconfig.
0022  */
0023 asm (
0024 "   .pushsection .rodata, \"a\"     \n"
0025 "   .ascii \"IKCFG_ST\"         \n"
0026 "   .global kernel_config_data      \n"
0027 "kernel_config_data:                \n"
0028 "   .incbin \"kernel/config_data.gz\"   \n"
0029 "   .global kernel_config_data_end      \n"
0030 "kernel_config_data_end:            \n"
0031 "   .ascii \"IKCFG_ED\"         \n"
0032 "   .popsection             \n"
0033 );
0034
0035 #ifdef CONFIG_IKCONFIG_PROC
0036
0037 extern char kernel_config_data;
0038 extern char kernel_config_data_end;
0039
0040 static ssize_t
0041 ikconfig_read_current(struct file *file, char __user *buf,
0042               size_t len, loff_t * offset)
0043 {
0044     return simple_read_from_buffer(buf, len, offset,
0045                        &kernel_config_data,
0046                        &kernel_config_data_end -
0047                        &kernel_config_data);
0048 }
0049
0050 static const struct proc_ops config_gz_proc_ops = {
0051     .proc_read  = ikconfig_read_current,
0052     .proc_lseek = default_llseek,
0053 };
0054
0055 static int __init ikconfig_init(void)
0056 {
0057     struct proc_dir_entry *entry;
0058
0059     /* create the current config file */
0060     entry = proc_create("config.gz", S_IFREG | S_IRUGO, NULL,
0061                 &config_gz_proc_ops);
0062     if (!entry)
0063         return -ENOMEM;
0064
0065     proc_set_size(entry, &kernel_config_data_end - &kernel_config_data);
0066
0067     return 0;
0068 }
0069
0070 static void __exit ikconfig_cleanup(void)
0071 {
0072     remove_proc_entry("config.gz", NULL);
0073 }
0074
0075 module_init(ikconfig_init);
0076 module_exit(ikconfig_cleanup);
0077
0078 #endif /* CONFIG_IKCONFIG_PROC */
0079
0080 MODULE_LICENSE("GPL");
0081 MODULE_AUTHOR("Randy Dunlap");
0082 MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");