/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  #include <linux/ptrace.h>
  #include <linux/version.h>
  #include <uapi/linux/bpf.h>

  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_tracing.h>

  
  struct pair {
  	u64 val;
  	u64 ip;
  };

  struct {
  	__uint(type, BPF_MAP_TYPE_HASH);
  	__type(key, long);
  	__type(value, struct pair);
  	__uint(max_entries, 1000000);
  } my_map SEC(".maps");

  
  /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
   * example will no longer be meaningful
   */
  SEC("kprobe/kmem_cache_free")
  int bpf_prog1(struct pt_regs *ctx)
  {

  	long ptr = PT_REGS_PARM2(ctx);

  
  	bpf_map_delete_elem(&my_map, &ptr);
  	return 0;
  }
  
  SEC("kretprobe/kmem_cache_alloc_node")
  int bpf_prog2(struct pt_regs *ctx)
  {

  	long ptr = PT_REGS_RC(ctx);

  	long ip = 0;
  
  	/* get ip address of kmem_cache_alloc_node() caller */

  	BPF_KRETPROBE_READ_RET_IP(ip, ctx);

  
  	struct pair v = {
  		.val = bpf_ktime_get_ns(),
  		.ip = ip,
  	};
  
  	bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY);
  	return 0;
  }
  char _license[] SEC("license") = "GPL";
  u32 _version SEC("version") = LINUX_VERSION_CODE;