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")
BPF_PROG(on_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";
47
