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;