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1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)2// Copyright (c) 2020 Facebook3#include "vmlinux.h"4#include <bpf/bpf_helpers.h>5#include <bpf/bpf_tracing.h>6 7/* map of perf event fds, num_cpu * num_metric entries */8struct {9 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);10 __uint(key_size, sizeof(__u32));11 __uint(value_size, sizeof(int));12} events SEC(".maps");13 14/* readings at fentry */15struct {16 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);17 __uint(key_size, sizeof(__u32));18 __uint(value_size, sizeof(struct bpf_perf_event_value));19 __uint(max_entries, 1);20} fentry_readings SEC(".maps");21 22/* accumulated readings */23struct {24 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);25 __uint(key_size, sizeof(__u32));26 __uint(value_size, sizeof(struct bpf_perf_event_value));27 __uint(max_entries, 1);28} accum_readings SEC(".maps");29 30const volatile __u32 num_cpu = 1;31 32SEC("fentry/XXX")33int BPF_PROG(fentry_XXX)34{35 __u32 key = bpf_get_smp_processor_id();36 struct bpf_perf_event_value *ptr;37 __u32 zero = 0;38 long err;39 40 /* look up before reading, to reduce error */41 ptr = bpf_map_lookup_elem(&fentry_readings, &zero);42 if (!ptr)43 return 0;44 45 err = bpf_perf_event_read_value(&events, key, ptr, sizeof(*ptr));46 if (err)47 return 0;48 49 return 0;50}51 52static inline void53fexit_update_maps(struct bpf_perf_event_value *after)54{55 struct bpf_perf_event_value *before, diff;56 __u32 zero = 0;57 58 before = bpf_map_lookup_elem(&fentry_readings, &zero);59 /* only account samples with a valid fentry_reading */60 if (before && before->counter) {61 struct bpf_perf_event_value *accum;62 63 diff.counter = after->counter - before->counter;64 diff.enabled = after->enabled - before->enabled;65 diff.running = after->running - before->running;66 67 accum = bpf_map_lookup_elem(&accum_readings, &zero);68 if (accum) {69 accum->counter += diff.counter;70 accum->enabled += diff.enabled;71 accum->running += diff.running;72 }73 }74}75 76SEC("fexit/XXX")77int BPF_PROG(fexit_XXX)78{79 struct bpf_perf_event_value reading;80 __u32 cpu = bpf_get_smp_processor_id();81 int err;82 83 /* read all events before updating the maps, to reduce error */84 err = bpf_perf_event_read_value(&events, cpu, &reading, sizeof(reading));85 if (err)86 return 0;87 88 fexit_update_maps(&reading);89 return 0;90}91 92char LICENSE[] SEC("license") = "Dual BSD/GPL";93