// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * kernel/configs.c
   * Echo the kernel .config file used to build the kernel
   *
   * Copyright (C) 2002 Khalid Aziz <khalid_aziz@hp.com>

   * Copyright (C) 2002 Randy Dunlap <rdunlap@xenotime.net>

   * Copyright (C) 2002 Al Stone <ahs3@fc.hp.com>
   * Copyright (C) 2002 Hewlett-Packard Company

   */

  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/init.h>

  #include <linux/uaccess.h>

  /*

   * "IKCFG_ST" and "IKCFG_ED" are used to extract the config data from
   * a binary kernel image or a module. See scripts/extract-ikconfig.

   */

  asm (
  "	.pushsection .rodata, \"a\"		
  "
  "	.ascii \"IKCFG_ST\"			
  "
  "	.global kernel_config_data		
  "
  "kernel_config_data:				
  "
  "	.incbin \"kernel/config_data.gz\"	
  "
  "	.global kernel_config_data_end		
  "
  "kernel_config_data_end:			
  "
  "	.ascii \"IKCFG_ED\"			
  "
  "	.popsection				
  "
  );

  
  #ifdef CONFIG_IKCONFIG_PROC

  extern char kernel_config_data;
  extern char kernel_config_data_end;

  static ssize_t
  ikconfig_read_current(struct file *file, char __user *buf,
  		      size_t len, loff_t * offset)
  {

  	return simple_read_from_buffer(buf, len, offset,

  				       &kernel_config_data,
  				       &kernel_config_data_end -
  				       &kernel_config_data);

  }

  static const struct file_operations ikconfig_file_ops = {

  	.owner = THIS_MODULE,
  	.read = ikconfig_read_current,

  	.llseek = default_llseek,

  };

  static int __init ikconfig_init(void)
  {
  	struct proc_dir_entry *entry;
  
  	/* create the current config file */

  	entry = proc_create("config.gz", S_IFREG | S_IRUGO, NULL,
  			    &ikconfig_file_ops);

  	if (!entry)
  		return -ENOMEM;

  	proc_set_size(entry, &kernel_config_data_end - &kernel_config_data);

  
  	return 0;
  }

  static void __exit ikconfig_cleanup(void)
  {

  	remove_proc_entry("config.gz", NULL);

  }
  
  module_init(ikconfig_init);
  module_exit(ikconfig_cleanup);

  #endif /* CONFIG_IKCONFIG_PROC */

  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Randy Dunlap");
  MODULE_DESCRIPTION("Echo the kernel .config file used to build the kernel");