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authorAlexei Starovoitov <ast@plumgrid.com>2014-12-01 15:06:38 -0800
committerDavid S. Miller <davem@davemloft.net>2014-12-05 21:47:33 -0800
commita80857822b0c2ed608c93504bd3687b78f20c619 (patch)
tree8fb218a13a13a16d5083c7b831398f967137f152 /samples/bpf/sockex1_kern.c
parent249b812d8005ec38e351ee763ceb85d56b155064 (diff)
downloadlinux-a80857822b0c2ed608c93504bd3687b78f20c619.tar.gz
samples: bpf: trivial eBPF program in C
this example does the same task as previous socket example in assembler, but this one does it in C. eBPF program in kernel does: /* assume that packet is IPv4, load one byte of IP->proto */ int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)); long *value; value = bpf_map_lookup_elem(&my_map, &index); if (value) __sync_fetch_and_add(value, 1); Corresponding user space reads map[tcp], map[udp], map[icmp] and prints protocol stats every second Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/sockex1_kern.c')
-rw-r--r--samples/bpf/sockex1_kern.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/samples/bpf/sockex1_kern.c b/samples/bpf/sockex1_kern.c
new file mode 100644
index 000000000000..066892662915
--- /dev/null
+++ b/samples/bpf/sockex1_kern.c
@@ -0,0 +1,25 @@
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/ip.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") my_map = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(long),
+ .max_entries = 256,
+};
+
+SEC("socket1")
+int bpf_prog1(struct sk_buff *skb)
+{
+ int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
+ long *value;
+
+ value = bpf_map_lookup_elem(&my_map, &index);
+ if (value)
+ __sync_fetch_and_add(value, 1);
+
+ return 0;
+}
+char _license[] SEC("license") = "GPL";