util/bpf_skel/bperf_leader.bpf.c

0001 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
0002 // Copyright (c) 2021 Facebook
0003 #include "vmlinux.h"
0004 #include <bpf/bpf_helpers.h>
0005 #include <bpf/bpf_tracing.h>
0006
0007 struct {
0008     __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
0009     __uint(key_size, sizeof(__u32));
0010     __uint(value_size, sizeof(int));
0011     __uint(map_flags, BPF_F_PRESERVE_ELEMS);
0012 } events SEC(".maps");
0013
0014 struct {
0015     __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
0016     __uint(key_size, sizeof(__u32));
0017     __uint(value_size, sizeof(struct bpf_perf_event_value));
0018     __uint(max_entries, 1);
0019 } prev_readings SEC(".maps");
0020
0021 struct {
0022     __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
0023     __uint(key_size, sizeof(__u32));
0024     __uint(value_size, sizeof(struct bpf_perf_event_value));
0025     __uint(max_entries, 1);
0026 } diff_readings SEC(".maps");
0027
0028 SEC("raw_tp/sched_switch")
0029 int BPF_PROG(on_switch)
0030 {
0031     struct bpf_perf_event_value val, *prev_val, *diff_val;
0032     __u32 key = bpf_get_smp_processor_id();
0033     __u32 zero = 0;
0034     long err;
0035
0036     prev_val = bpf_map_lookup_elem(&prev_readings, &zero);
0037     if (!prev_val)
0038         return 0;
0039
0040     diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
0041     if (!diff_val)
0042         return 0;
0043
0044     err = bpf_perf_event_read_value(&events, key, &val, sizeof(val));
0045     if (err)
0046         return 0;
0047
0048     diff_val->counter = val.counter - prev_val->counter;
0049     diff_val->enabled = val.enabled - prev_val->enabled;
0050     diff_val->running = val.running - prev_val->running;
0051     *prev_val = val;
0052     return 0;
0053 }
0054
0055 char LICENSE[] SEC("license") = "Dual BSD/GPL";