1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3 
4 #include <linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6 #include "bpf_misc.h"
7 
8 char _license[] SEC("license") = "GPL";
9 
10 struct sample {
11 	int pid;
12 	int seq;
13 	long value;
14 	char comm[16];
15 };
16 
17 struct {
18 	__uint(type, BPF_MAP_TYPE_RINGBUF);
19 } ringbuf SEC(".maps");
20 
21 struct {
22 	__uint(type, BPF_MAP_TYPE_HASH);
23 	__uint(max_entries, 1000);
24 	__type(key, struct sample);
25 	__type(value, int);
26 } hash_map SEC(".maps");
27 
28 /* inputs */
29 int pid = 0;
30 
31 /* inner state */
32 long seq = 0;
33 
34 SEC("fentry/" SYS_PREFIX "sys_getpgid")
35 int test_ringbuf_mem_map_key(void *ctx)
36 {
37 	int cur_pid = bpf_get_current_pid_tgid() >> 32;
38 	struct sample *sample, sample_copy;
39 	int *lookup_val;
40 
41 	if (cur_pid != pid)
42 		return 0;
43 
44 	sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
45 	if (!sample)
46 		return 0;
47 
48 	sample->pid = pid;
49 	bpf_get_current_comm(sample->comm, sizeof(sample->comm));
50 	sample->seq = ++seq;
51 	sample->value = 42;
52 
53 	/* test using 'sample' (PTR_TO_MEM | MEM_ALLOC) as map key arg
54 	 */
55 	lookup_val = (int *)bpf_map_lookup_elem(&hash_map, sample);
56 
57 	/* workaround - memcpy is necessary so that verifier doesn't
58 	 * complain with:
59 	 *   verifier internal error: more than one arg with ref_obj_id R3
60 	 * when trying to do bpf_map_update_elem(&hash_map, sample, &sample->seq, BPF_ANY);
61 	 *
62 	 * Since bpf_map_lookup_elem above uses 'sample' as key, test using
63 	 * sample field as value below
64 	 */
65 	__builtin_memcpy(&sample_copy, sample, sizeof(struct sample));
66 	bpf_map_update_elem(&hash_map, &sample_copy, &sample->seq, BPF_ANY);
67 
68 	bpf_ringbuf_submit(sample, 0);
69 	return 0;
70 }
71