// 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\"             \n"
"       .ascii \"IKCFG_ST\"                     \n"
"       .global kernel_config_data              \n"
"kernel_config_data:                            \n"
"       .incbin \"kernel/config_data.gz\"       \n"
"       .global kernel_config_data_end          \n"
"kernel_config_data_end:                        \n"
"       .ascii \"IKCFG_ED\"                     \n"
"       .popsection                             \n"
);

#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 proc_ops config_gz_proc_ops = {
        .proc_read      = ikconfig_read_current,
        .proc_lseek     = 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,
                            &config_gz_proc_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");