tools/perf/util/bpf_skel/bperf_follower.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 #include "bperf_u.h"
   7
   8 struct {
   9         __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  10         __uint(key_size, sizeof(__u32));
  11         __uint(value_size, sizeof(struct bpf_perf_event_value));
  12         __uint(max_entries, 1);
  13 } diff_readings SEC(".maps");
  14
  15 struct {
  16         __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  17         __uint(key_size, sizeof(__u32));
  18         __uint(value_size, sizeof(struct bpf_perf_event_value));
  19         __uint(max_entries, 1);
  20 } accum_readings SEC(".maps");
  21
  22 struct {
  23         __uint(type, BPF_MAP_TYPE_HASH);
  24         __uint(key_size, sizeof(__u32));
  25         __uint(value_size, sizeof(__u32));
  26 } filter SEC(".maps");
  27
  28 enum bperf_filter_type type = 0;
  29 int enabled = 0;
  30
  31 SEC("fexit/XXX")
  32 int BPF_PROG(fexit_XXX)
  33 {
  34         struct bpf_perf_event_value *diff_val, *accum_val;
  35         __u32 filter_key, zero = 0;
  36         __u32 *accum_key;
  37
  38         if (!enabled)
  39                 return 0;
  40
  41         switch (type) {
  42         case BPERF_FILTER_GLOBAL:
  43                 accum_key = &zero;
  44                 goto do_add;
  45         case BPERF_FILTER_CPU:
  46                 filter_key = bpf_get_smp_processor_id();
  47                 break;
  48         case BPERF_FILTER_PID:
  49                 filter_key = bpf_get_current_pid_tgid() & 0xffffffff;
  50                 break;
  51         case BPERF_FILTER_TGID:
  52                 filter_key = bpf_get_current_pid_tgid() >> 32;
  53                 break;
  54         default:
  55                 return 0;
  56         }
  57
  58         accum_key = bpf_map_lookup_elem(&filter, &filter_key);
  59         if (!accum_key)
  60                 return 0;
  61
  62 do_add:
  63         diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
  64         if (!diff_val)
  65                 return 0;
  66
  67         accum_val = bpf_map_lookup_elem(&accum_readings, accum_key);
  68         if (!accum_val)
  69                 return 0;
  70
  71         accum_val->counter += diff_val->counter;
  72         accum_val->enabled += diff_val->enabled;
  73         accum_val->running += diff_val->running;
  74
  75         return 0;
  76 }
  77
  78 char LICENSE[] SEC("license") = "Dual BSD/GPL";