56 lines
1.4 KiB
C
56 lines
1.4 KiB
C
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// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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// Copyright (c) 2021 Facebook
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(int));
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__uint(map_flags, BPF_F_PRESERVE_ELEMS);
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} events SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(struct bpf_perf_event_value));
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__uint(max_entries, 1);
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} prev_readings SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(struct bpf_perf_event_value));
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__uint(max_entries, 1);
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} diff_readings SEC(".maps");
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SEC("raw_tp/sched_switch")
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int BPF_PROG(on_switch)
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{
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struct bpf_perf_event_value val, *prev_val, *diff_val;
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__u32 key = bpf_get_smp_processor_id();
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__u32 zero = 0;
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long err;
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prev_val = bpf_map_lookup_elem(&prev_readings, &zero);
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if (!prev_val)
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return 0;
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diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
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if (!diff_val)
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return 0;
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err = bpf_perf_event_read_value(&events, key, &val, sizeof(val));
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if (err)
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return 0;
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diff_val->counter = val.counter - prev_val->counter;
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diff_val->enabled = val.enabled - prev_val->enabled;
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diff_val->running = val.running - prev_val->running;
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*prev_val = val;
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return 0;
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}
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char LICENSE[] SEC("license") = "Dual BSD/GPL";
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