LXR linux/tools/perf/util/bpf_skel/bperf

   1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2// Copyright (c) 2021 Facebook
   3#include <linux/bpf.h>
   4#include <linux/perf_event.h>
   5#include <bpf/bpf_helpers.h>
   6#include <bpf/bpf_tracing.h>
   7#include "bperf.h"
   8
   9struct {
  10        __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
  11        __uint(key_size, sizeof(__u32));
  12        __uint(value_size, sizeof(int));
  13        __uint(map_flags, BPF_F_PRESERVE_ELEMS);
  14} events SEC(".maps");
  15
  16reading_map prev_readings SEC(".maps");
  17reading_map diff_readings SEC(".maps");
  18
  19SEC("raw_tp/sched_switch")
  20int BPF_PROG(on_switch)
  21{
  22        struct bpf_perf_event_value val, *prev_val, *diff_val;
  23        __u32 key = bpf_get_smp_processor_id();
  24        __u32 zero = 0;
  25        long err;
  26
  27        prev_val = bpf_map_lookup_elem(&prev_readings, &zero);
  28        if (!prev_val)
  29                return 0;
  30
  31        diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
  32        if (!diff_val)
  33                return 0;
  34
  35        err = bpf_perf_event_read_value(&events, key, &val, sizeof(val));
  36        if (err)
  37                return 0;
  38
  39        diff_val->counter = val.counter - prev_val->counter;
  40        diff_val->enabled = val.enabled - prev_val->enabled;
  41        diff_val->running = val.running - prev_val->running;
  42        *prev_val = val;
  43        return 0;
  44}
  45
  46char LICENSE[] SEC("license") = "Dual BSD/GPL";
  47