kernel/bpf/sysfs_btf.c

   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
  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
  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);