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
26struct 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
36struct 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
44static 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
57static 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
66SEC("len_hist")
67int 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
82char _license[] SEC("license") = "GPL";