LXR linux/samples/bpf/xdp_sample_pkts

   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
   9struct {
  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
  15SEC("xdp_sample")
  16int 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
  56char _license[] SEC("license") = "GPL";
  57u32 _version SEC("version") = LINUX_VERSION_CODE;
  58