xref: /openbmc/linux/kernel/bpf/sysfs_btf.c (revision 36e68442)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Provide kernel BTF information for introspection and use by eBPF tools.
4  */
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/kobject.h>
8 #include <linux/init.h>
9 #include <linux/sysfs.h>
10 
11 /* See scripts/link-vmlinux.sh, gen_btf() func for details */
12 extern char __weak __start_BTF[];
13 extern char __weak __stop_BTF[];
14 
15 static ssize_t
btf_vmlinux_read(struct file * file,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t len)16 btf_vmlinux_read(struct file *file, struct kobject *kobj,
17 		 struct bin_attribute *bin_attr,
18 		 char *buf, loff_t off, size_t len)
19 {
20 	memcpy(buf, __start_BTF + off, len);
21 	return len;
22 }
23 
24 static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = {
25 	.attr = { .name = "vmlinux", .mode = 0444, },
26 	.read = btf_vmlinux_read,
27 };
28 
29 struct kobject *btf_kobj;
30 
btf_vmlinux_init(void)31 static int __init btf_vmlinux_init(void)
32 {
33 	bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF;
34 
35 	if (!__start_BTF || bin_attr_btf_vmlinux.size == 0)
36 		return 0;
37 
38 	btf_kobj = kobject_create_and_add("btf", kernel_kobj);
39 	if (!btf_kobj)
40 		return -ENOMEM;
41 
42 	return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_vmlinux);
43 }
44 
45 subsys_initcall(btf_vmlinux_init);
46