samples/bpf/tracex4.bpf.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 "vmlinux.h"
   8 #include <linux/version.h>
   9 #include <bpf/bpf_helpers.h>
  10 #include <bpf/bpf_tracing.h>
  11
  12 struct pair {
  13         u64 val;
  14         u64 ip;
  15 };
  16
  17 struct {
  18         __uint(type, BPF_MAP_TYPE_HASH);
  19         __type(key, long);
  20         __type(value, struct pair);
  21         __uint(max_entries, 1000000);
  22 } my_map SEC(".maps");
  23
  24 /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
  25  * example will no longer be meaningful
  26  */
  27 SEC("kprobe/kmem_cache_free")
  28 int bpf_prog1(struct pt_regs *ctx)
  29 {
  30         long ptr = PT_REGS_PARM2(ctx);
  31
  32         bpf_map_delete_elem(&my_map, &ptr);
  33         return 0;
  34 }
  35
  36 SEC("kretprobe/kmem_cache_alloc_node_noprof")
  37 int bpf_prog2(struct pt_regs *ctx)
  38 {
  39         long ptr = PT_REGS_RC(ctx);
  40         long ip = 0;
  41
  42         /* get ip address of kmem_cache_alloc_node_noprof() caller */
  43         BPF_KRETPROBE_READ_RET_IP(ip, ctx);
  44
  45         struct pair v = {
  46                 .val = bpf_ktime_get_ns(),
  47                 .ip = ip,
  48         };
  49
  50         bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY);
  51         return 0;
  52 }
  53 char _license[] SEC("license") = "GPL";
  54 u32 _version SEC("version") = LINUX_VERSION_CODE;