LXR linux/samples/bpf/tracex4

   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
  13struct pair {
  14        u64 val;
  15        u64 ip;
  16};
  17
  18struct {
  19        __uint(type, BPF_MAP_TYPE_HASH);
  20        __type(key, long);
  21        __type(value, struct pair);
  22        __uint(max_entries, 1000000);
  23} my_map SEC(".maps");
  24
  25/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
  26 * example will no longer be meaningful
  27 */
  28SEC("kprobe/kmem_cache_free")
  29int 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
  37SEC("kretprobe/kmem_cache_alloc_node")
  38int 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}
  54char _license[] SEC("license") = "GPL";
  55u32 _version SEC("version") = LINUX_VERSION_CODE;
  56