63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
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/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
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__type(key, u64);
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__type(value, u64);
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__uint(pinning, LIBBPF_PIN_BY_NAME);
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__uint(max_entries, 1024);
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} lwt_len_hist_map SEC(".maps");
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static unsigned int log2(unsigned int v)
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{
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unsigned int r;
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unsigned int shift;
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r = (v > 0xFFFF) << 4; v >>= r;
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shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
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shift = (v > 0xF) << 2; v >>= shift; r |= shift;
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shift = (v > 0x3) << 1; v >>= shift; r |= shift;
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r |= (v >> 1);
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return r;
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}
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static unsigned int log2l(unsigned long v)
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{
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unsigned int hi = v >> 32;
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if (hi)
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return log2(hi) + 32;
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else
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return log2(v);
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}
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SEC("len_hist")
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int do_len_hist(struct __sk_buff *skb)
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{
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__u64 *value, key, init_val = 1;
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key = log2l(skb->len);
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value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);
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if (value)
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__sync_fetch_and_add(value, 1);
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else
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bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);
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return BPF_OK;
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}
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char _license[] SEC("license") = "GPL";
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