ebpf_exporter

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#include <vmlinux.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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#include "maps.bpf.h"
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// 27 buckets for latency, max range is 33.6s .. 67.1s
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#define MAX_LATENCY_SLOT 26
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// Max number of listening ports we expect to see on the host
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#define MAX_PORTS 1024
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struct socket_latency_key_t {
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    u16 port;
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    u64 bucket;
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};
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struct {
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    __uint(type, BPF_MAP_TYPE_HASH);
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    __uint(max_entries, 10240);
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    __type(key, struct request_sock *);
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    __type(value, u64);
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} start SEC(".maps");
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struct {
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    __uint(type, BPF_MAP_TYPE_HASH);
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    __uint(max_entries, (MAX_LATENCY_SLOT + 1) * MAX_PORTS);
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    __type(key, struct socket_latency_key_t);
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    __type(value, u64);
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} accept_latency_seconds SEC(".maps");
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SEC("kprobe/inet_csk_reqsk_queue_hash_add")
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int BPF_KPROBE(kprobe__inet_csk_reqsk_queue_hash_add, struct sock *sk, struct request_sock *req)
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{
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    u64 ts = bpf_ktime_get_ns();
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    bpf_map_update_elem(&start, &req, &ts, BPF_ANY);
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    return 0;
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}
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SEC("kprobe/inet_csk_accept")
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int BPF_KPROBE(kprobe__inet_csk_accept, struct sock *sk)
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{
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    u64 *tsp, delta_us, ts = bpf_ktime_get_ns();
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    struct inet_connection_sock *icsk = (struct inet_connection_sock *) sk;
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    struct request_sock *req = BPF_CORE_READ(icsk, icsk_accept_queue).rskq_accept_head;
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    struct socket_latency_key_t key = {};
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    tsp = bpf_map_lookup_elem(&start, &req);
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    if (!tsp) {
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        return 0;
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    }
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    delta_us = (ts - *tsp) / 1000;
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    key.port = BPF_CORE_READ(sk, __sk_common).skc_num;
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    increment_exp2_histogram(&accept_latency_seconds, key, delta_us, MAX_LATENCY_SLOT);
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    bpf_map_delete_elem(&start, &req);
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    return 0;
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}
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char LICENSE[] SEC("license") = "GPL";
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