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1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)2// Copyright (c) 2021 Facebook3#include "vmlinux.h"4#include <bpf/bpf_helpers.h>5#include <bpf/bpf_tracing.h>6 7struct {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 14struct {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 21struct {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 28SEC("raw_tp/sched_switch")29int 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 55char LICENSE[] SEC("license") = "Dual BSD/GPL";56