1/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
 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
 8#include <linux/ptrace.h>
 9#include <uapi/linux/bpf.h>
10#include <linux/version.h>
11#include <bpf/bpf_helpers.h>
12#include <uapi/linux/utsname.h>
13#include "trace_common.h"
14
15struct {
16	__uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
17	__uint(key_size, sizeof(u32));
18	__uint(value_size, sizeof(u32));
19	__uint(max_entries, 1);
20} cgroup_map SEC(".maps");
21
22struct {
23	__uint(type, BPF_MAP_TYPE_ARRAY);
24	__type(key, u32);
25	__type(value, u64);
26	__uint(max_entries, 1);
27} perf_map SEC(".maps");
28
29/* Writes the last PID that called sync to a map at index 0 */
30SEC("kprobe/" SYSCALL(sys_sync))
31int bpf_prog1(struct pt_regs *ctx)
32{
33	u64 pid = bpf_get_current_pid_tgid();
34	int idx = 0;
35
36	if (!bpf_current_task_under_cgroup(&cgroup_map, 0))
37		return 0;
38
39	bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY);
40	return 0;
41}
42
43char _license[] SEC("license") = "GPL";
44u32 _version SEC("version") = LINUX_VERSION_CODE;