1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Provide kernel headers useful to build tracing programs
4 * such as for running eBPF tracing tools.
5 *
6 * (Borrowed code from kernel/configs.c)
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/kobject.h>
12#include <linux/init.h>
13
14/*
15 * Define kernel_headers_data and kernel_headers_data_end, within which the
16 * compressed kernel headers are stored. The file is first compressed with xz.
17 */
18
19asm (
20"	.pushsection .rodata, \"a\"		\n"
21"	.global kernel_headers_data		\n"
22"kernel_headers_data:				\n"
23"	.incbin \"kernel/kheaders_data.tar.xz\"	\n"
24"	.global kernel_headers_data_end		\n"
25"kernel_headers_data_end:			\n"
26"	.popsection				\n"
27);
28
29extern char kernel_headers_data[];
30extern char kernel_headers_data_end[];
31
32static ssize_t
33ikheaders_read(struct file *file,  struct kobject *kobj,
34	       struct bin_attribute *bin_attr,
35	       char *buf, loff_t off, size_t len)
36{
37	memcpy(buf, &kernel_headers_data[off], len);
38	return len;
39}
40
41static struct bin_attribute kheaders_attr __ro_after_init = {
42	.attr = {
43		.name = "kheaders.tar.xz",
44		.mode = 0444,
45	},
46	.read = &ikheaders_read,
47};
48
49static int __init ikheaders_init(void)
50{
51	kheaders_attr.size = (kernel_headers_data_end -
52			      kernel_headers_data);
53	return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
54}
55
56static void __exit ikheaders_cleanup(void)
57{
58	sysfs_remove_bin_file(kernel_kobj, &kheaders_attr);
59}
60
61module_init(ikheaders_init);
62module_exit(ikheaders_cleanup);
63
64MODULE_LICENSE("GPL v2");
65MODULE_AUTHOR("Joel Fernandes");
66MODULE_DESCRIPTION("Echo the kernel header artifacts used to build the kernel");
67