93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
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// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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// Copyright (c) 2020 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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/* map of perf event fds, num_cpu * num_metric entries */
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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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} events SEC(".maps");
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/* readings at fentry */
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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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} fentry_readings SEC(".maps");
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/* accumulated readings */
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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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} accum_readings SEC(".maps");
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const volatile __u32 num_cpu = 1;
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SEC("fentry/XXX")
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int BPF_PROG(fentry_XXX)
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{
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__u32 key = bpf_get_smp_processor_id();
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struct bpf_perf_event_value *ptr;
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__u32 zero = 0;
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long err;
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/* look up before reading, to reduce error */
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ptr = bpf_map_lookup_elem(&fentry_readings, &zero);
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if (!ptr)
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return 0;
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err = bpf_perf_event_read_value(&events, key, ptr, sizeof(*ptr));
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if (err)
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return 0;
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return 0;
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}
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static inline void
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fexit_update_maps(struct bpf_perf_event_value *after)
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{
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struct bpf_perf_event_value *before, diff;
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__u32 zero = 0;
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before = bpf_map_lookup_elem(&fentry_readings, &zero);
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/* only account samples with a valid fentry_reading */
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if (before && before->counter) {
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struct bpf_perf_event_value *accum;
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diff.counter = after->counter - before->counter;
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diff.enabled = after->enabled - before->enabled;
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diff.running = after->running - before->running;
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accum = bpf_map_lookup_elem(&accum_readings, &zero);
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if (accum) {
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accum->counter += diff.counter;
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accum->enabled += diff.enabled;
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accum->running += diff.running;
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}
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}
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}
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SEC("fexit/XXX")
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int BPF_PROG(fexit_XXX)
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{
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struct bpf_perf_event_value reading;
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__u32 cpu = bpf_get_smp_processor_id();
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int err;
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/* read all events before updating the maps, to reduce error */
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err = bpf_perf_event_read_value(&events, cpu, &reading, sizeof(reading));
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if (err)
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return 0;
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fexit_update_maps(&reading);
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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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