| 1 | /* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch> |
|---|
| 2 | * |
|---|
| 3 | * This program is free software; you can redistribute it and/or |
|---|
| 4 | * modify it under the terms of version 2 of the GNU General Public |
|---|
| 5 | * License as published by the Free Software Foundation. |
|---|
| 6 | * |
|---|
| 7 | * This program is distributed in the hope that it will be useful, but |
|---|
| 8 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
|---|
| 9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|---|
| 10 | * General Public License for more details. |
|---|
| 11 | */ |
|---|
| 12 | |
|---|
| 13 | #include "vmlinux.h" |
|---|
| 14 | #include <bpf/bpf_helpers.h> |
|---|
| 15 | |
|---|
| 16 | struct { |
|---|
| 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 | |
|---|
| 24 | static 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 | |
|---|
| 37 | static unsigned int log2l(unsigned long v) |
|---|
| 38 | { |
|---|
| 39 | unsigned int hi = v >> 32; |
|---|
| 40 | if (hi) |
|---|
| 41 | return log2(v: hi) + 32; |
|---|
| 42 | else |
|---|
| 43 | return log2(v); |
|---|
| 44 | } |
|---|
| 45 | |
|---|
| 46 | SEC("len_hist" ) |
|---|
| 47 | int 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 | else |
|---|
| 57 | bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY); |
|---|
| 58 | |
|---|
| 59 | return BPF_OK; |
|---|
| 60 | } |
|---|
| 61 | |
|---|
| 62 | char _license[] SEC("license" ) = "GPL" ; |
|---|
| 63 | |
|---|
