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f74599f7 TG |
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 | ||
e8acf8f4 | 13 | #include "vmlinux.h" |
7cf245a3 | 14 | #include <bpf/bpf_helpers.h> |
f74599f7 | 15 | |
a1f93c8f DL |
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"); | |
f74599f7 TG |
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(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"; |