79 lines
1.6 KiB
C
79 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
// Copyright (c) 2020 Facebook
|
|
|
|
#include <linux/bpf.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include "bpf_misc.h"
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
|
|
struct sample {
|
|
int pid;
|
|
int seq;
|
|
long value;
|
|
char comm[16];
|
|
};
|
|
|
|
struct {
|
|
__uint(type, BPF_MAP_TYPE_RINGBUF);
|
|
} ringbuf SEC(".maps");
|
|
|
|
/* inputs */
|
|
int pid = 0;
|
|
long value = 0;
|
|
long flags = 0;
|
|
|
|
/* outputs */
|
|
long total = 0;
|
|
long discarded = 0;
|
|
long dropped = 0;
|
|
|
|
long avail_data = 0;
|
|
long ring_size = 0;
|
|
long cons_pos = 0;
|
|
long prod_pos = 0;
|
|
|
|
/* inner state */
|
|
long seq = 0;
|
|
|
|
SEC("fentry/" SYS_PREFIX "sys_getpgid")
|
|
int test_ringbuf(void *ctx)
|
|
{
|
|
int cur_pid = bpf_get_current_pid_tgid() >> 32;
|
|
struct sample *sample;
|
|
int zero = 0;
|
|
|
|
if (cur_pid != pid)
|
|
return 0;
|
|
|
|
sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
|
|
if (!sample) {
|
|
__sync_fetch_and_add(&dropped, 1);
|
|
return 0;
|
|
}
|
|
|
|
sample->pid = pid;
|
|
bpf_get_current_comm(sample->comm, sizeof(sample->comm));
|
|
sample->value = value;
|
|
|
|
sample->seq = seq++;
|
|
__sync_fetch_and_add(&total, 1);
|
|
|
|
if (sample->seq & 1) {
|
|
/* copy from reserved sample to a new one... */
|
|
bpf_ringbuf_output(&ringbuf, sample, sizeof(*sample), flags);
|
|
/* ...and then discard reserved sample */
|
|
bpf_ringbuf_discard(sample, flags);
|
|
__sync_fetch_and_add(&discarded, 1);
|
|
} else {
|
|
bpf_ringbuf_submit(sample, flags);
|
|
}
|
|
|
|
avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA);
|
|
ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE);
|
|
cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS);
|
|
prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS);
|
|
|
|
return 0;
|
|
}
|