tools/perf/util/bpf_skel/bperf_leader.bpf.c

   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
   9 struct {
  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
  16 reading_map prev_readings SEC(".maps");
  17 reading_map diff_readings SEC(".maps");
  18
  19 SEC("raw_tp/sched_switch")
  20 int 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
  46 char LICENSE[] SEC("license") = "Dual BSD/GPL";