LXR linux/tools/testing/selftests/bpf/progs/test_ringbuf

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (c) 2020 Facebook
   3
   4#include <linux/bpf.h>
   5#include <bpf/bpf_helpers.h>
   6
   7char _license[] SEC("license") = "GPL";
   8
   9struct sample {
  10        int pid;
  11        int seq;
  12        long value;
  13        char comm[16];
  14};
  15
  16struct ringbuf_map {
  17        __uint(type, BPF_MAP_TYPE_RINGBUF);
  18        __uint(max_entries, 1 << 12);
  19} ringbuf1 SEC(".maps"),
  20  ringbuf2 SEC(".maps");
  21
  22struct {
  23        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
  24        __uint(max_entries, 4);
  25        __type(key, int);
  26        __array(values, struct ringbuf_map);
  27} ringbuf_arr SEC(".maps") = {
  28        .values = {
  29                [0] = &ringbuf1,
  30                [2] = &ringbuf2,
  31        },
  32};
  33
  34/* inputs */
  35int pid = 0;
  36int target_ring = 0;
  37long value = 0;
  38
  39/* outputs */
  40long total = 0;
  41long dropped = 0;
  42long skipped = 0;
  43
  44SEC("tp/syscalls/sys_enter_getpgid")
  45int test_ringbuf(void *ctx)
  46{
  47        int cur_pid = bpf_get_current_pid_tgid() >> 32;
  48        struct sample *sample;
  49        void *rb;
  50        int zero = 0;
  51
  52        if (cur_pid != pid)
  53                return 0;
  54
  55        rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring);
  56        if (!rb) {
  57                skipped += 1;
  58                return 1;
  59        }
  60
  61        sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0);
  62        if (!sample) {
  63                dropped += 1;
  64                return 1;
  65        }
  66
  67        sample->pid = pid;
  68        bpf_get_current_comm(sample->comm, sizeof(sample->comm));
  69        sample->value = value;
  70
  71        sample->seq = total;
  72        total += 1;
  73
  74        bpf_ringbuf_submit(sample, 0);
  75
  76        return 0;
  77}
  78