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