Add sample for adding simple drop program to link

Add a sample program that only drops packets at the BPF_PROG_TYPE_XDP_RX
hook of a link. With the drop-only program, observed single core rate is
~20Mpps.

Other tests were run, for instance without the dropcnt increment or
without reading from the packet header, the packet rate was mostly
unchanged.

$ perf record -a samples/bpf/xdp1 $(</sys/class/net/eth0/ifindex)
proto 17:   20403027 drops/s

./pktgen_sample03_burst_single_flow.sh -i $DEV -d $IP -m $MAC -t 4
Running... ctrl^C to stop
Device: eth4@0
Result: OK: 11791017(c11788327+d2689) usec, 59622913 (60byte,0frags)
  5056638pps 2427Mb/sec (2427186240bps) errors: 0
Device: eth4@1
Result: OK: 11791012(c11787906+d3106) usec, 60526944 (60byte,0frags)
  5133311pps 2463Mb/sec (2463989280bps) errors: 0
Device: eth4@2
Result: OK: 11791019(c11788249+d2769) usec, 59868091 (60byte,0frags)
  5077431pps 2437Mb/sec (2437166880bps) errors: 0
Device: eth4@3
Result: OK: 11795039(c11792403+d2636) usec, 59483181 (60byte,0frags)
  5043067pps 2420Mb/sec (2420672160bps) errors: 0

perf report --no-children:
 26.05%  ksoftirqd/0  [mlx4_en]         [k] mlx4_en_process_rx_cq
 17.84%  ksoftirqd/0  [mlx4_en]         [k] mlx4_en_alloc_frags
  5.52%  ksoftirqd/0  [mlx4_en]         [k] mlx4_en_free_frag
  4.90%  swapper      [kernel.vmlinux]  [k] poll_idle
  4.14%  ksoftirqd/0  [kernel.vmlinux]  [k] get_page_from_freelist
  2.78%  ksoftirqd/0  [kernel.vmlinux]  [k] __free_pages_ok
  2.57%  ksoftirqd/0  [kernel.vmlinux]  [k] bpf_map_lookup_elem
  2.51%  swapper      [mlx4_en]         [k] mlx4_en_process_rx_cq
  1.94%  ksoftirqd/0  [kernel.vmlinux]  [k] percpu_array_map_lookup_elem
  1.45%  swapper      [mlx4_en]         [k] mlx4_en_alloc_frags
  1.35%  ksoftirqd/0  [kernel.vmlinux]  [k] free_one_page
  1.33%  swapper      [kernel.vmlinux]  [k] intel_idle
  1.04%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c5c5
  0.96%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c58d
  0.93%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c6ee
  0.92%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c6b9
  0.89%  ksoftirqd/0  [kernel.vmlinux]  [k] __alloc_pages_nodemask
  0.83%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c686
  0.83%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c5d5
  0.78%  ksoftirqd/0  [mlx4_en]         [k] mlx4_alloc_pages.isra.23
  0.77%  ksoftirqd/0  [mlx4_en]         [k] 0x000000000001c5b4
  0.77%  ksoftirqd/0  [kernel.vmlinux]  [k] net_rx_action

machine specs:
 receiver - Intel E5-1630 v3 @ 3.70GHz
 sender - Intel E5645 @ 2.40GHz
 Mellanox ConnectX-3 @40G

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 286 insertions, 0 deletions

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index a98b780e974c..0e4ab3a9dfa9 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -21,6 +21,7 @@ hostprogs-y += spintest
 hostprogs-y += map_perf_test
 hostprogs-y += test_overhead
 hostprogs-y += test_cgrp2_array_pin
+hostprogs-y += xdp1
 
 test_verifier-objs := test_verifier.o libbpf.o
 test_maps-objs := test_maps.o libbpf.o
@@ -42,6 +43,7 @@ spintest-objs := bpf_load.o libbpf.o spintest_user.o
 map_perf_test-objs := bpf_load.o libbpf.o map_perf_test_user.o
 test_overhead-objs := bpf_load.o libbpf.o test_overhead_user.o
 test_cgrp2_array_pin-objs := libbpf.o test_cgrp2_array_pin.o
+xdp1-objs := bpf_load.o libbpf.o xdp1_user.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -64,6 +66,7 @@ always += test_overhead_tp_kern.o
 always += test_overhead_kprobe_kern.o
 always += parse_varlen.o parse_simple.o parse_ldabs.o
 always += test_cgrp2_tc_kern.o
+always += xdp1_kern.o
 
 HOSTCFLAGS += -I$(objtree)/usr/include
 
@@ -84,6 +87,7 @@ HOSTLOADLIBES_offwaketime += -lelf
 HOSTLOADLIBES_spintest += -lelf
 HOSTLOADLIBES_map_perf_test += -lelf -lrt
 HOSTLOADLIBES_test_overhead += -lelf -lrt
+HOSTLOADLIBES_xdp1 += -lelf
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
 #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 022af71c2bb5..0cfda2320320 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -50,6 +50,7 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
         bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
         bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
         bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
+        bool is_xdp = strncmp(event, "xdp", 3) == 0;
         enum bpf_prog_type prog_type;
         char buf[256];
         int fd, efd, err, id;
@@ -66,6 +67,8 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
                 prog_type = BPF_PROG_TYPE_KPROBE;
         } else if (is_tracepoint) {
                 prog_type = BPF_PROG_TYPE_TRACEPOINT;
+        } else if (is_xdp) {
+                prog_type = BPF_PROG_TYPE_XDP;
         } else {
                 printf("Unknown event '%s'\n", event);
                 return -1;
@@ -79,6 +82,9 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 
         prog_fd[prog_cnt++] = fd;
 
+        if (is_xdp)
+                return 0;
+
         if (is_socket) {
                 event += 6;
                 if (*event != '/')
@@ -319,6 +325,7 @@ int load_bpf_file(char *path)
                         if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
                             memcmp(shname_prog, "kretprobe/", 10) == 0 ||
                             memcmp(shname_prog, "tracepoint/", 11) == 0 ||
+                            memcmp(shname_prog, "xdp", 3) == 0 ||
                             memcmp(shname_prog, "socket", 6) == 0)
                                 load_and_attach(shname_prog, insns, data_prog->d_size);
                 }
@@ -336,6 +343,7 @@ int load_bpf_file(char *path)
                 if (memcmp(shname, "kprobe/", 7) == 0 ||
                     memcmp(shname, "kretprobe/", 10) == 0 ||
                     memcmp(shname, "tracepoint/", 11) == 0 ||
+                    memcmp(shname, "xdp", 3) == 0 ||
                     memcmp(shname, "socket", 6) == 0)
                         load_and_attach(shname, data->d_buf, data->d_size);
         }
diff --git a/samples/bpf/xdp1_kern.c b/samples/bpf/xdp1_kern.c
new file mode 100644
index 000000000000..e7dd8ac40d12
--- /dev/null
+++ b/samples/bpf/xdp1_kern.c
@@ -0,0 +1,93 @@
+/* Copyright (c) 2016 PLUMgrid
+ *
+ * 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.
+ */
+#define KBUILD_MODNAME "foo"
+#include <uapi/linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") dropcnt = {
+        .type = BPF_MAP_TYPE_PERCPU_ARRAY,
+        .key_size = sizeof(u32),
+        .value_size = sizeof(long),
+        .max_entries = 256,
+};
+
+static int parse_ipv4(void *data, u64 nh_off, void *data_end)
+{
+        struct iphdr *iph = data + nh_off;
+
+        if (iph + 1 > data_end)
+                return 0;
+        return iph->protocol;
+}
+
+static int parse_ipv6(void *data, u64 nh_off, void *data_end)
+{
+        struct ipv6hdr *ip6h = data + nh_off;
+
+        if (ip6h + 1 > data_end)
+                return 0;
+        return ip6h->nexthdr;
+}
+
+SEC("xdp1")
+int xdp_prog1(struct xdp_md *ctx)
+{
+        void *data_end = (void *)(long)ctx->data_end;
+        void *data = (void *)(long)ctx->data;
+        struct ethhdr *eth = data;
+        int rc = XDP_DROP;
+        long *value;
+        u16 h_proto;
+        u64 nh_off;
+        u32 index;
+
+        nh_off = sizeof(*eth);
+        if (data + nh_off > data_end)
+                return rc;
+
+        h_proto = eth->h_proto;
+
+        if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
+                struct vlan_hdr *vhdr;
+
+                vhdr = data + nh_off;
+                nh_off += sizeof(struct vlan_hdr);
+                if (data + nh_off > data_end)
+                        return rc;
+                h_proto = vhdr->h_vlan_encapsulated_proto;
+        }
+        if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
+                struct vlan_hdr *vhdr;
+
+                vhdr = data + nh_off;
+                nh_off += sizeof(struct vlan_hdr);
+                if (data + nh_off > data_end)
+                        return rc;
+                h_proto = vhdr->h_vlan_encapsulated_proto;
+        }
+
+        if (h_proto == htons(ETH_P_IP))
+                index = parse_ipv4(data, nh_off, data_end);
+        else if (h_proto == htons(ETH_P_IPV6))
+                index = parse_ipv6(data, nh_off, data_end);
+        else
+                index = 0;
+
+        value = bpf_map_lookup_elem(&dropcnt, &index);
+        if (value)
+                *value += 1;
+
+        return rc;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/x