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";
56
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.