kernel/configs.c

   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  */
  23 asm (
  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
  37 extern char kernel_config_data;
  38 extern char kernel_config_data_end;
  39
  40 static ssize_t
  41 ikconfig_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
  50 static const struct file_operations ikconfig_file_ops = {
  51         .owner = THIS_MODULE,
  52         .read = ikconfig_read_current,
  53         .llseek = default_llseek,
  54 };
  55
  56 static int __init ikconfig_init(void)
  57 {
  58         struct proc_dir_entry *entry;
  59
  60         /* create the current config file */
  61         entry = proc_create("config.gz", S_IFREG | S_IRUGO, NULL,
  62                             &ikconfig_file_ops);
  63         if (!entry)
  64                 return -ENOMEM;
  65
  66         proc_set_size(entry, &kernel_config_data_end - &kernel_config_data);
  67
  68         return 0;
  69 }
  70
  71 static void __exit ikconfig_cleanup(void)
  72 {
  73         remove_proc_entry("config.gz", NULL);
  74 }
  75
  76 module_init(ikconfig_init);
  77 module_exit(ikconfig_cleanup);
  78
  79 #endif /* CONFIG_IKCONFIG_PROC */
  80
  81 MODULE_LICENSE("GPL");
  82 MODULE_AUTHOR("Randy Dunlap");
  83 MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");