1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/bpf.h>
4 #include <bpf/bpf_helpers.h>
5 #include "bpf_misc.h"
6
7 char _license[] SEC("license") = "GPL";
8
9 struct {
10 __uint(type, BPF_MAP_TYPE_RINGBUF);
11 } ringbuf SEC(".maps");
12
13 /* inputs */
14 int pid = 0;
15
16 /* outputs */
17 long passed = 0;
18 long discarded = 0;
19
20 SEC("fentry/" SYS_PREFIX "sys_getpgid")
21 int test_ringbuf_write(void *ctx)
22 {
23 int *foo, cur_pid = bpf_get_current_pid_tgid() >> 32;
24 void *sample1, *sample2;
25
26 if (cur_pid != pid)
27 return 0;
28
29 sample1 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
30 if (!sample1)
31 return 0;
32 /* first one can pass */
33 sample2 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
34 if (!sample2) {
35 bpf_ringbuf_discard(sample1, 0);
36 __sync_fetch_and_add(&discarded, 1);
37 return 0;
38 }
39 /* second one must not */
40 __sync_fetch_and_add(&passed, 1);
41 foo = sample2 + 4084;
42 *foo = 256;
43 bpf_ringbuf_discard(sample1, 0);
44 bpf_ringbuf_discard(sample2, 0);
45 return 0;
46 }
47
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