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/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
__type(key, u64);
__type(value, u64);
__uint(pinning, LIBBPF_PIN_BY_NAME);
__uint(max_entries, 1024);
} lwt_len_hist_map SEC(".maps");
static unsigned int log2(unsigned int v)
{
unsigned int r;
unsigned int shift;
r = (v > 0xFFFF) << 4; v >>= r;
shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
shift = (v > 0xF) << 2; v >>= shift; r |= shift;
shift = (v > 0x3) << 1; v >>= shift; r |= shift;
r |= (v >> 1);
return r;
}
static unsigned int log2l(unsigned long v)
{
unsigned int hi = v >> 32;
if (hi)
return log2(hi) + 32;
else
return log2(v);
}
SEC("len_hist")
int do_len_hist(struct __sk_buff *skb)
{
__u64 *value, key, init_val = 1;
key = log2l(skb->len);
value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);
if (value)
__sync_fetch_and_add(value, 1);
else
bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);
return BPF_OK;
}
char _license[] SEC("license") = "GPL";
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