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 "vmlinux.h"
   4 #include <bpf/bpf_helpers.h>
   5 #include <bpf/bpf_tracing.h>
   6
   7 struct {
   8         __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
   9         __uint(key_size, sizeof(__u32));
  10         __uint(value_size, sizeof(int));
  11         __uint(map_flags, BPF_F_PRESERVE_ELEMS);
  12 } events SEC(".maps");
  13
  14 struct {
  15         __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  16         __uint(key_size, sizeof(__u32));
  17         __uint(value_size, sizeof(struct bpf_perf_event_value));
  18         __uint(max_entries, 1);
  19 } prev_readings SEC(".maps");
  20
  21 struct {
  22         __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  23         __uint(key_size, sizeof(__u32));
  24         __uint(value_size, sizeof(struct bpf_perf_event_value));
  25         __uint(max_entries, 1);
  26 } diff_readings SEC(".maps");
  27
  28 SEC("raw_tp/sched_switch")
  29 int BPF_PROG(on_switch)
  30 {
  31         struct bpf_perf_event_value val, *prev_val, *diff_val;
  32         __u32 key = bpf_get_smp_processor_id();
  33         __u32 zero = 0;
  34         long err;
  35
  36         prev_val = bpf_map_lookup_elem(&prev_readings, &zero);
  37         if (!prev_val)
  38                 return 0;
  39
  40         diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
  41         if (!diff_val)
  42                 return 0;
  43
  44         err = bpf_perf_event_read_value(&events, key, &val, sizeof(val));
  45         if (err)
  46                 return 0;
  47
  48         diff_val->counter = val.counter - prev_val->counter;
  49         diff_val->enabled = val.enabled - prev_val->enabled;
  50         diff_val->running = val.running - prev_val->running;
  51         *prev_val = val;
  52         return 0;
  53 }
  54
  55 char LICENSE[] SEC("license") = "Dual BSD/GPL";