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 # define printk(fmt, ...) \
20 ({ \
21 char ____fmt[] = fmt; \
22 bpf_trace_printk(____fmt, sizeof(____fmt), \
23 ##__VA_ARGS__); \
24 })
25
26 struct bpf_elf_map {
27 __u32 type;
28 __u32 size_key;
29 __u32 size_value;
30 __u32 max_elem;
31 __u32 flags;
32 __u32 id;
33 __u32 pinning;
34 };
35
36 struct bpf_elf_map SEC("maps") lwt_len_hist_map = {
37 .type = BPF_MAP_TYPE_PERCPU_HASH,
38 .size_key = sizeof(__u64),
39 .size_value = sizeof(__u64),
40 .pinning = 2,
41 .max_elem = 1024,
42 };
43
log2(unsigned int v)44 static unsigned int log2(unsigned int v)
45 {
46 unsigned int r;
47 unsigned int shift;
48
49 r = (v > 0xFFFF) << 4; v >>= r;
50 shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
51 shift = (v > 0xF) << 2; v >>= shift; r |= shift;
52 shift = (v > 0x3) << 1; v >>= shift; r |= shift;
53 r |= (v >> 1);
54 return r;
55 }
56
log2l(unsigned long v)57 static unsigned int log2l(unsigned long v)
58 {
59 unsigned int hi = v >> 32;
60 if (hi)
61 return log2(hi) + 32;
62 else
63 return log2(v);
64 }
65
66 SEC("len_hist")
do_len_hist(struct __sk_buff * skb)67 int do_len_hist(struct __sk_buff *skb)
68 {
69 __u64 *value, key, init_val = 1;
70
71 key = log2l(skb->len);
72
73 value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);
74 if (value)
75 __sync_fetch_and_add(value, 1);
76 else
77 bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);
78
79 return BPF_OK;
80 }
81
82 char _license[] SEC("license") = "GPL";
83