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 
7 char _license[] SEC("license") = "GPL";
8 
9 struct sample {
10 	int pid;
11 	int seq;
12 	long value;
13 	char comm[16];
14 };
15 
16 struct ringbuf_map {
17 	__uint(type, BPF_MAP_TYPE_RINGBUF);
18 } ringbuf1 SEC(".maps"),
19   ringbuf2 SEC(".maps");
20 
21 struct {
22 	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
23 	__uint(max_entries, 4);
24 	__type(key, int);
25 	__array(values, struct ringbuf_map);
26 } ringbuf_arr SEC(".maps") = {
27 	.values = {
28 		[0] = &ringbuf1,
29 		[2] = &ringbuf2,
30 	},
31 };
32 
33 struct {
34 	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
35 	__uint(max_entries, 1);
36 	__type(key, int);
37 	__array(values, struct ringbuf_map);
38 } ringbuf_hash SEC(".maps") = {
39 	.values = {
40 		[0] = &ringbuf1,
41 	},
42 };
43 
44 /* inputs */
45 int pid = 0;
46 int target_ring = 0;
47 long value = 0;
48 
49 /* outputs */
50 long total = 0;
51 long dropped = 0;
52 long skipped = 0;
53 
54 SEC("tp/syscalls/sys_enter_getpgid")
55 int test_ringbuf(void *ctx)
56 {
57 	int cur_pid = bpf_get_current_pid_tgid() >> 32;
58 	struct sample *sample;
59 	void *rb;
60 	int zero = 0;
61 
62 	if (cur_pid != pid)
63 		return 0;
64 
65 	rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring);
66 	if (!rb) {
67 		skipped += 1;
68 		return 1;
69 	}
70 
71 	sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0);
72 	if (!sample) {
73 		dropped += 1;
74 		return 1;
75 	}
76 
77 	sample->pid = pid;
78 	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
79 	sample->value = value;
80 
81 	sample->seq = total;
82 	total += 1;
83 
84 	bpf_ringbuf_submit(sample, 0);
85 
86 	return 0;
87 }
88