47 lines · c
1// SPDX-License-Identifier: GPL-2.02 3#include <linux/bpf.h>4#include <bpf/bpf_helpers.h>5#include "bpf_misc.h"6 7char _license[] SEC("license") = "GPL";8 9struct {10 __uint(type, BPF_MAP_TYPE_RINGBUF);11} ringbuf SEC(".maps");12 13/* inputs */14int pid = 0;15 16/* outputs */17long passed = 0;18long discarded = 0;19 20SEC("fentry/" SYS_PREFIX "sys_getpgid")21int 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