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 <uapi/linux/bpf.h>
14 #include <uapi/linux/if_ether.h>
15 #include <uapi/linux/ip.h>
16 #include <uapi/linux/in.h>
17 #include <bpf/bpf_helpers.h>
18
19 struct bpf_elf_map {
20 __u32 type;
21 __u32 size_key;
22 __u32 size_value;
23 __u32 max_elem;
24 __u32 flags;
25 __u32 id;
26 __u32 pinning;
27 };
28
29 struct bpf_elf_map SEC("maps") lwt_len_hist_map = {
30 .type = BPF_MAP_TYPE_PERCPU_HASH,
31 .size_key = sizeof(__u64),
32 .size_value = sizeof(__u64),
33 .pinning = 2,
34 .max_elem = 1024,
35 };
36
log2(unsigned int v)37 static unsigned int log2(unsigned int v)
38 {
39 unsigned int r;
40 unsigned int shift;
41
42 r = (v > 0xFFFF) << 4; v >>= r;
43 shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
44 shift = (v > 0xF) << 2; v >>= shift; r |= shift;
45 shift = (v > 0x3) << 1; v >>= shift; r |= shift;
46 r |= (v >> 1);
47 return r;
48 }
49
log2l(unsigned long v)50 static unsigned int log2l(unsigned long v)
51 {
52 unsigned int hi = v >> 32;
53 if (hi)
54 return log2(hi) + 32;
55 else
56 return log2(v);
57 }
58
59 SEC("len_hist")
do_len_hist(struct __sk_buff * skb)60 int do_len_hist(struct __sk_buff *skb)
61 {
62 __u64 *value, key, init_val = 1;
63
64 key = log2l(skb->len);
65
66 value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);
67 if (value)
68 __sync_fetch_and_add(value, 1);
69 else
70 bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);
71
72 return BPF_OK;
73 }
74
75 char _license[] SEC("license") = "GPL";
76