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bpf: Add tests and samples for LWT-BPF
Adds a series of tests to verify the functionality of attaching BPF programs at LWT hooks. Also adds a sample which collects a histogram of packet sizes which pass through an LWT hook. $ ./lwt_len_hist.sh Starting netserver with host 'IN(6)ADDR_ANY' port '12865' and family AF_UNSPEC MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.253.2 () port 0 AF_INET : demo Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.00 39857.69 1 -> 1 : 0 | | 2 -> 3 : 0 | | 4 -> 7 : 0 | | 8 -> 15 : 0 | | 16 -> 31 : 0 | | 32 -> 63 : 22 | | 64 -> 127 : 98 | | 128 -> 255 : 213 | | 256 -> 511 : 1444251 |******** | 512 -> 1023 : 660610 |*** | 1024 -> 2047 : 535241 |** | 2048 -> 4095 : 19 | | 4096 -> 8191 : 180 | | 8192 -> 16383 : 5578023 |************************************* | 16384 -> 32767 : 632099 |*** | 32768 -> 65535 : 6575 | | Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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‎samples/bpf/Makefile‎

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@@ -29,6 +29,7 @@ hostprogs-y += test_current_task_under_cgroup
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hostprogs-y += trace_event
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hostprogs-y += sampleip
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hostprogs-y += tc_l2_redirect
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hostprogs-y += lwt_len_hist
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test_lru_dist-objs := test_lru_dist.o libbpf.o
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sock_example-objs := sock_example.o libbpf.o
@@ -59,6 +60,7 @@ test_current_task_under_cgroup-objs := bpf_load.o libbpf.o \
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trace_event-objs := bpf_load.o libbpf.o trace_event_user.o
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sampleip-objs := bpf_load.o libbpf.o sampleip_user.o
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tc_l2_redirect-objs := bpf_load.o libbpf.o tc_l2_redirect_user.o
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lwt_len_hist-objs := bpf_load.o libbpf.o lwt_len_hist_user.o
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# Tell kbuild to always build the programs
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always := $(hostprogs-y)
@@ -89,6 +91,7 @@ always += xdp2_kern.o
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always += test_current_task_under_cgroup_kern.o
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always += trace_event_kern.o
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always += sampleip_kern.o
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always += lwt_len_hist_kern.o
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HOSTCFLAGS += -I$(objtree)/usr/include
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HOSTCFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
@@ -117,6 +120,7 @@ HOSTLOADLIBES_test_current_task_under_cgroup += -lelf
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HOSTLOADLIBES_trace_event += -lelf
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HOSTLOADLIBES_sampleip += -lelf
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HOSTLOADLIBES_tc_l2_redirect += -l elf
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HOSTLOADLIBES_lwt_len_hist += -l elf
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# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
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# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

‎samples/bpf/bpf_helpers.h‎

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@@ -80,6 +80,8 @@ struct bpf_map_def {
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unsigned int map_flags;
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};
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static int (*bpf_skb_load_bytes)(void *ctx, int off, void *to, int len) =
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(void *) BPF_FUNC_skb_load_bytes;
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static int (*bpf_skb_store_bytes)(void *ctx, int off, void *from, int len, int flags) =
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(void *) BPF_FUNC_skb_store_bytes;
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static int (*bpf_l3_csum_replace)(void *ctx, int off, int from, int to, int flags) =
@@ -88,6 +90,8 @@ static int (*bpf_l4_csum_replace)(void *ctx, int off, int from, int to, int flag
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(void *) BPF_FUNC_l4_csum_replace;
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static int (*bpf_skb_under_cgroup)(void *ctx, void *map, int index) =
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(void *) BPF_FUNC_skb_under_cgroup;
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static int (*bpf_skb_change_head)(void *, int len, int flags) =
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(void *) BPF_FUNC_skb_change_head;
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#if defined(__x86_64__)
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‎samples/bpf/lwt_len_hist.sh‎

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@@ -0,0 +1,37 @@
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#!/bin/bash
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NS1=lwt_ns1
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VETH0=tst_lwt1a
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VETH1=tst_lwt1b
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TRACE_ROOT=/sys/kernel/debug/tracing
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function cleanup {
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ip route del 192.168.253.2/32 dev $VETH0 2> /dev/null
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ip link del $VETH0 2> /dev/null
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ip link del $VETH1 2> /dev/null
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ip netns exec $NS1 killall netserver
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ip netns delete $NS1 2> /dev/null
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}
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cleanup
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ip netns add $NS1
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ip link add $VETH0 type veth peer name $VETH1
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ip link set dev $VETH0 up
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ip addr add 192.168.253.1/24 dev $VETH0
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ip link set $VETH1 netns $NS1
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ip netns exec $NS1 ip link set dev $VETH1 up
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ip netns exec $NS1 ip addr add 192.168.253.2/24 dev $VETH1
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ip netns exec $NS1 netserver
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echo 1 > ${TRACE_ROOT}/tracing_on
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cp /dev/null ${TRACE_ROOT}/trace
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ip route add 192.168.253.2/32 encap bpf out obj lwt_len_hist_kern.o section len_hist dev $VETH0
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netperf -H 192.168.253.2 -t TCP_STREAM
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cat ${TRACE_ROOT}/trace | grep -v '^#'
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./lwt_len_hist
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cleanup
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echo 0 > ${TRACE_ROOT}/tracing_on
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exit 0

‎samples/bpf/lwt_len_hist_kern.c‎

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/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <uapi/linux/bpf.h>
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#include <uapi/linux/if_ether.h>
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#include <uapi/linux/ip.h>
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#include <uapi/linux/in.h>
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#include "bpf_helpers.h"
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# define printk(fmt, ...) \
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({ \
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char ____fmt[] = fmt; \
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bpf_trace_printk(____fmt, sizeof(____fmt), \
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##__VA_ARGS__); \
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})
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struct bpf_elf_map {
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__u32 type;
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__u32 size_key;
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__u32 size_value;
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__u32 max_elem;
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__u32 flags;
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__u32 id;
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__u32 pinning;
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};
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struct bpf_elf_map SEC("maps") lwt_len_hist_map = {
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.type = BPF_MAP_TYPE_PERCPU_HASH,
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.size_key = sizeof(__u64),
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.size_value = sizeof(__u64),
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.pinning = 2,
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.max_elem = 1024,
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};
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static unsigned int log2(unsigned int v)
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{
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unsigned int r;
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unsigned int shift;
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r = (v > 0xFFFF) << 4; v >>= r;
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shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
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shift = (v > 0xF) << 2; v >>= shift; r |= shift;
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shift = (v > 0x3) << 1; v >>= shift; r |= shift;
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r |= (v >> 1);
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return r;
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}
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static unsigned int log2l(unsigned long v)
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{
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unsigned int hi = v >> 32;
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if (hi)
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return log2(hi) + 32;
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else
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return log2(v);
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}
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SEC("len_hist")
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int do_len_hist(struct __sk_buff *skb)
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{
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__u64 *value, key, init_val = 1;
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key = log2l(skb->len);
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value = bpf_map_lookup_elem(&lwt_len_hist_map, &key);
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if (value)
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__sync_fetch_and_add(value, 1);
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else
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bpf_map_update_elem(&lwt_len_hist_map, &key, &init_val, BPF_ANY);
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return BPF_OK;
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}
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char _license[] SEC("license") = "GPL";

‎samples/bpf/lwt_len_hist_user.c‎

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#include <linux/unistd.h>
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#include <linux/bpf.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <arpa/inet.h>
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#include "libbpf.h"
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#include "bpf_util.h"
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#define MAX_INDEX 64
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#define MAX_STARS 38
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static void stars(char *str, long val, long max, int width)
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{
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int i;
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for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
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str[i] = '*';
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if (val > max)
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str[i - 1] = '+';
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str[i] = '\0';
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}
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int main(int argc, char **argv)
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{
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unsigned int nr_cpus = bpf_num_possible_cpus();
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const char *map_filename = "/sys/fs/bpf/tc/globals/lwt_len_hist_map";
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uint64_t values[nr_cpus], sum, max_value = 0, data[MAX_INDEX] = {};
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uint64_t key = 0, next_key, max_key = 0;
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char starstr[MAX_STARS];
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int i, map_fd;
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map_fd = bpf_obj_get(map_filename);
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if (map_fd < 0) {
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fprintf(stderr, "bpf_obj_get(%s): %s(%d)\n",
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map_filename, strerror(errno), errno);
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return -1;
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}
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while (bpf_get_next_key(map_fd, &key, &next_key) == 0) {
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if (next_key >= MAX_INDEX) {
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fprintf(stderr, "Key %lu out of bounds\n", next_key);
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continue;
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}
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bpf_lookup_elem(map_fd, &next_key, values);
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sum = 0;
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for (i = 0; i < nr_cpus; i++)
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sum += values[i];
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data[next_key] = sum;
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if (sum && next_key > max_key)
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max_key = next_key;
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if (sum > max_value)
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max_value = sum;
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key = next_key;
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}
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for (i = 1; i <= max_key + 1; i++) {
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stars(starstr, data[i - 1], max_value, MAX_STARS);
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printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
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(1l << i) >> 1, (1l << i) - 1, data[i - 1],
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MAX_STARS, starstr);
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}
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close(map_fd);
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return 0;
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}

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