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_helpers.h"
6
7 #define SAMPLE_SIZE 64ul
8 #define MAX_CPUS 128
9
10 #define bpf_printk(fmt, ...) \
11 ({ \
12 char ____fmt[] = fmt; \
13 bpf_trace_printk(____fmt, sizeof(____fmt), \
14 ##__VA_ARGS__); \
15 })
16
17 struct bpf_map_def SEC("maps") my_map = {
18 .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
19 .key_size = sizeof(int),
20 .value_size = sizeof(u32),
21 .max_entries = MAX_CPUS,
22 };
23
24 SEC("xdp_sample")
xdp_sample_prog(struct xdp_md * ctx)25 int xdp_sample_prog(struct xdp_md *ctx)
26 {
27 void *data_end = (void *)(long)ctx->data_end;
28 void *data = (void *)(long)ctx->data;
29
30 /* Metadata will be in the perf event before the packet data. */
31 struct S {
32 u16 cookie;
33 u16 pkt_len;
34 } __packed metadata;
35
36 if (data < data_end) {
37 /* The XDP perf_event_output handler will use the upper 32 bits
38 * of the flags argument as a number of bytes to include of the
39 * packet payload in the event data. If the size is too big, the
40 * call to bpf_perf_event_output will fail and return -EFAULT.
41 *
42 * See bpf_xdp_event_output in net/core/filter.c.
43 *
44 * The BPF_F_CURRENT_CPU flag means that the event output fd
45 * will be indexed by the CPU number in the event map.
46 */
47 u64 flags = BPF_F_CURRENT_CPU;
48 u16 sample_size;
49 int ret;
50
51 metadata.cookie = 0xdead;
52 metadata.pkt_len = (u16)(data_end - data);
53 sample_size = min(metadata.pkt_len, SAMPLE_SIZE);
54 flags |= (u64)sample_size << 32;
55
56 ret = bpf_perf_event_output(ctx, &my_map, flags,
57 &metadata, sizeof(metadata));
58 if (ret)
59 bpf_printk("perf_event_output failed: %d\n", ret);
60 }
61
62 return XDP_PASS;
63 }
64
65 char _license[] SEC("license") = "GPL";
66 u32 _version SEC("version") = LINUX_VERSION_CODE;
67
