72 lines
1.3 KiB
C
72 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Google LLC. */
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#include "vmlinux.h"
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#include <bpf/bpf_core_read.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "funclatency.h"
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#include "bits.bpf.h"
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const volatile pid_t targ_tgid = 0;
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const volatile int units = 0;
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/* key: pid. value: start time */
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, MAX_PIDS);
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__type(key, u32);
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__type(value, u64);
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} starts SEC(".maps");
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__u32 hist[MAX_SLOTS] = {};
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SEC("kprobe/dummy_kprobe")
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int BPF_KPROBE(dummy_kprobe)
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{
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u64 id = bpf_get_current_pid_tgid();
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u32 tgid = id >> 32;
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u32 pid = id;
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u64 nsec;
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if (targ_tgid && targ_tgid != tgid)
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return 0;
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nsec = bpf_ktime_get_ns();
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bpf_map_update_elem(&starts, &pid, &nsec, BPF_ANY);
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return 0;
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}
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SEC("kretprobe/dummy_kretprobe")
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int BPF_KRETPROBE(dummy_kretprobe)
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{
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u64 *start;
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u64 nsec = bpf_ktime_get_ns();
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u64 id = bpf_get_current_pid_tgid();
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u32 pid = id;
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u64 slot, delta;
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start = bpf_map_lookup_elem(&starts, &pid);
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if (!start)
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return 0;
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delta = nsec - *start;
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switch (units) {
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case USEC:
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delta /= 1000;
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break;
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case MSEC:
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delta /= 1000000;
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break;
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}
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slot = log2l(delta);
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if (slot >= MAX_SLOTS)
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slot = MAX_SLOTS - 1;
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__sync_fetch_and_add(&hist[slot], 1);
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return 0;
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}
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char LICENSE[] SEC("license") = "GPL";
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