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1/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>2 *3 * This program is free software; you can redistribute it and/or4 * modify it under the terms of version 2 of the GNU General Public5 * License as published by the Free Software Foundation.6 *7 * This program is distributed in the hope that it will be useful, but8 * WITHOUT ANY WARRANTY; without even the implied warranty of9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU10 * General Public License for more details.11 */12 13#include "vmlinux.h"14#include <bpf/bpf_helpers.h>15 16struct {17 __uint(type, BPF_MAP_TYPE_PERCPU_HASH);18 __type(key, u64);19 __type(value, u64);20 __uint(pinning, LIBBPF_PIN_BY_NAME);21 __uint(max_entries, 1024);22} lwt_len_hist_map SEC(".maps");23 24static unsigned int log2(unsigned int v)25{26 unsigned int r;27 unsigned int shift;28 29 r = (v > 0xFFFF) << 4; v >>= r;30 shift = (v > 0xFF) << 3; v >>= shift; r |= shift;31 shift = (v > 0xF) << 2; v >>= shift; r |= shift;32 shift = (v > 0x3) << 1; v >>= shift; r |= shift;33 r |= (v >> 1);34 return r;35}36 37static unsigned int log2l(unsigned long v)38{39 unsigned int hi = v >> 32;40 if (hi)41 return log2(hi) + 32;42 else43 return log2(v);44}45 46SEC("len_hist")47int do_len_hist(struct __sk_buff *skb)48{49 __u64 *value, key, init_val = 1;50 51 key = log2l(skb->len);52 53 value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);54 if (value)55 __sync_fetch_and_add(value, 1);56 else57 bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);58 59 return BPF_OK;60}61 62char _license[] SEC("license") = "GPL";63