samples/bpf/tracex4_kern.c

   1 /* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #include <linux/ptrace.h>
   8 #include <linux/version.h>
   9 #include <uapi/linux/bpf.h>
  10 #include <bpf/bpf_helpers.h>
  11 #include <bpf/bpf_tracing.h>
  12
  13 struct pair {
  14         u64 val;
  15         u64 ip;
  16 };
  17
  18 struct bpf_map_def SEC("maps") my_map = {
  19         .type = BPF_MAP_TYPE_HASH,
  20         .key_size = sizeof(long),
  21         .value_size = sizeof(struct pair),
  22         .max_entries = 1000000,
  23 };
  24
  25 /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
  26  * example will no longer be meaningful
  27  */
  28 SEC("kprobe/kmem_cache_free")
  29 int bpf_prog1(struct pt_regs *ctx)
  30 {
  31         long ptr = PT_REGS_PARM2(ctx);
  32
  33         bpf_map_delete_elem(&my_map, &ptr);
  34         return 0;
  35 }
  36
  37 SEC("kretprobe/kmem_cache_alloc_node")
  38 int bpf_prog2(struct pt_regs *ctx)
  39 {
  40         long ptr = PT_REGS_RC(ctx);
  41         long ip = 0;
  42
  43         /* get ip address of kmem_cache_alloc_node() caller */
  44         BPF_KRETPROBE_READ_RET_IP(ip, ctx);
  45
  46         struct pair v = {
  47                 .val = bpf_ktime_get_ns(),
  48                 .ip = ip,
  49         };
  50
  51         bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY);
  52         return 0;
  53 }
  54 char _license[] SEC("license") = "GPL";
  55 u32 _version SEC("version") = LINUX_VERSION_CODE;