1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/ptrace.h>
3 #include <linux/version.h>
4 #include <uapi/linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6
7 #define SAMPLE_SIZE 64ul
8
9 struct {
10 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
11 __uint(key_size, sizeof(int));
12 __uint(value_size, sizeof(u32));
13 } my_map SEC(".maps");
14
15 SEC("xdp_sample")
xdp_sample_prog(struct xdp_md * ctx)16 int xdp_sample_prog(struct xdp_md *ctx)
17 {
18 void *data_end = (void *)(long)ctx->data_end;
19 void *data = (void *)(long)ctx->data;
20
21 /* Metadata will be in the perf event before the packet data. */
22 struct S {
23 u16 cookie;
24 u16 pkt_len;
25 } __packed metadata;
26
27 if (data < data_end) {
28 /* The XDP perf_event_output handler will use the upper 32 bits
29 * of the flags argument as a number of bytes to include of the
30 * packet payload in the event data. If the size is too big, the
31 * call to bpf_perf_event_output will fail and return -EFAULT.
32 *
33 * See bpf_xdp_event_output in net/core/filter.c.
34 *
35 * The BPF_F_CURRENT_CPU flag means that the event output fd
36 * will be indexed by the CPU number in the event map.
37 */
38 u64 flags = BPF_F_CURRENT_CPU;
39 u16 sample_size;
40 int ret;
41
42 metadata.cookie = 0xdead;
43 metadata.pkt_len = (u16)(data_end - data);
44 sample_size = min(metadata.pkt_len, SAMPLE_SIZE);
45 flags |= (u64)sample_size << 32;
46
47 ret = bpf_perf_event_output(ctx, &my_map, flags,
48 &metadata, sizeof(metadata));
49 if (ret)
50 bpf_printk("perf_event_output failed: %d\n", ret);
51 }
52
53 return XDP_PASS;
54 }
55
56 char _license[] SEC("license") = "GPL";
57 u32 _version SEC("version") = LINUX_VERSION_CODE;
58