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