samples/bpf/sampleip_kern.c

   1 /* Copyright 2016 Netflix, Inc.
   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/version.h>
   8 #include <linux/ptrace.h>
   9 #include <uapi/linux/bpf.h>
  10 #include <uapi/linux/bpf_perf_event.h>
  11 #include "bpf_helpers.h"
  12
  13 #define MAX_IPS         8192
  14
  15 struct bpf_map_def SEC("maps") ip_map = {
  16         .type = BPF_MAP_TYPE_HASH,
  17         .key_size = sizeof(u64),
  18         .value_size = sizeof(u32),
  19         .max_entries = MAX_IPS,
  20 };
  21
  22 SEC("perf_event")
  23 int do_sample(struct bpf_perf_event_data *ctx)
  24 {
  25         u64 ip;
  26         u32 *value, init_val = 1;
  27
  28         ip = PT_REGS_IP(&ctx->regs);
  29         value = bpf_map_lookup_elem(&ip_map, &ip);
  30         if (value)
  31                 *value += 1;
  32         else
  33                 /* E2BIG not tested for this example only */
  34                 bpf_map_update_elem(&ip_map, &ip, &init_val, BPF_NOEXIST);
  35
  36         return 0;
  37 }
  38 char _license[] SEC("license") = "GPL";