1// SPDX-License-Identifier: GPL-2.0
 2// Copyright (c) 2020 Facebook
 3
 4#include <linux/bpf.h>
 5#include <bpf/bpf_helpers.h>
 6
 7char _license[] SEC("license") = "GPL";
 8
 9struct sample {
10	int pid;
11	int seq;
12	long value;
13	char comm[16];
14};
15
16struct ringbuf_map {
17	__uint(type, BPF_MAP_TYPE_RINGBUF);
18	__uint(max_entries, 1 << 12);
19} ringbuf1 SEC(".maps"),
20  ringbuf2 SEC(".maps");
21
22struct {
23	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
24	__uint(max_entries, 4);
25	__type(key, int);
26	__array(values, struct ringbuf_map);
27} ringbuf_arr SEC(".maps") = {
28	.values = {
29		[0] = &ringbuf1,
30		[2] = &ringbuf2,
31	},
32};
33
34/* inputs */
35int pid = 0;
36int target_ring = 0;
37long value = 0;
38
39/* outputs */
40long total = 0;
41long dropped = 0;
42long skipped = 0;
43
44SEC("tp/syscalls/sys_enter_getpgid")
45int test_ringbuf(void *ctx)
46{
47	int cur_pid = bpf_get_current_pid_tgid() >> 32;
48	struct sample *sample;
49	void *rb;
50	int zero = 0;
51
52	if (cur_pid != pid)
53		return 0;
54
55	rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring);
56	if (!rb) {
57		skipped += 1;
58		return 1;
59	}
60
61	sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0);
62	if (!sample) {
63		dropped += 1;
64		return 1;
65	}
66
67	sample->pid = pid;
68	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
69	sample->value = value;
70
71	sample->seq = total;
72	total += 1;
73
74	bpf_ringbuf_submit(sample, 0);
75
76	return 0;
77}