117 lines
2.1 KiB
C
117 lines
2.1 KiB
C
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// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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// Copyright (c) 2021 Google
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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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// This should be in sync with "util/ftrace.h"
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#define NUM_BUCKET 22
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(key_size, sizeof(__u64));
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__uint(value_size, sizeof(__u64));
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__uint(max_entries, 10000);
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} functime SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(__u8));
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__uint(max_entries, 1);
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} cpu_filter SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(__u8));
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__uint(max_entries, 1);
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} task_filter 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(__u64));
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__uint(max_entries, NUM_BUCKET);
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} latency SEC(".maps");
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int enabled = 0;
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int has_cpu = 0;
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int has_task = 0;
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int use_nsec = 0;
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SEC("kprobe/func")
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int BPF_PROG(func_begin)
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{
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__u64 key, now;
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if (!enabled)
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return 0;
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key = bpf_get_current_pid_tgid();
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if (has_cpu) {
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__u32 cpu = bpf_get_smp_processor_id();
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__u8 *ok;
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ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
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if (!ok)
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return 0;
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}
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if (has_task) {
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__u32 pid = key & 0xffffffff;
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__u8 *ok;
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ok = bpf_map_lookup_elem(&task_filter, &pid);
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if (!ok)
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return 0;
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}
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now = bpf_ktime_get_ns();
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// overwrite timestamp for nested functions
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bpf_map_update_elem(&functime, &key, &now, BPF_ANY);
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return 0;
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}
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SEC("kretprobe/func")
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int BPF_PROG(func_end)
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{
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__u64 tid;
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__u64 *start;
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__u64 cmp_base = use_nsec ? 1 : 1000;
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if (!enabled)
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return 0;
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tid = bpf_get_current_pid_tgid();
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start = bpf_map_lookup_elem(&functime, &tid);
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if (start) {
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__s64 delta = bpf_ktime_get_ns() - *start;
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__u32 key;
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__u64 *hist;
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bpf_map_delete_elem(&functime, &tid);
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if (delta < 0)
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return 0;
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// calculate index using delta
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for (key = 0; key < (NUM_BUCKET - 1); key++) {
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if (delta < (cmp_base << key))
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break;
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}
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hist = bpf_map_lookup_elem(&latency, &key);
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if (!hist)
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return 0;
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*hist += 1;
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}
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return 0;
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}
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