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-rw-r--r--samples/bpf/xdp_sample_pkts_kern.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/samples/bpf/xdp_sample_pkts_kern.c b/samples/bpf/xdp_sample_pkts_kern.c
new file mode 100644
index 000000000000..f7ca8b850978
--- /dev/null
+++ b/samples/bpf/xdp_sample_pkts_kern.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ptrace.h>
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+#define SAMPLE_SIZE 64ul
+#define MAX_CPUS 128
+
+#define bpf_printk(fmt, ...) \
+({ \
+ char ____fmt[] = fmt; \
+ bpf_trace_printk(____fmt, sizeof(____fmt), \
+ ##__VA_ARGS__); \
+})
+
+struct bpf_map_def SEC("maps") my_map = {
+ .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(u32),
+ .max_entries = MAX_CPUS,
+};
+
+SEC("xdp_sample")
+int xdp_sample_prog(struct xdp_md *ctx)
+{
+ void *data_end = (void *)(long)ctx->data_end;
+ void *data = (void *)(long)ctx->data;
+
+ /* Metadata will be in the perf event before the packet data. */
+ struct S {
+ u16 cookie;
+ u16 pkt_len;
+ } __packed metadata;
+
+ if (data < data_end) {
+ /* The XDP perf_event_output handler will use the upper 32 bits
+ * of the flags argument as a number of bytes to include of the
+ * packet payload in the event data. If the size is too big, the
+ * call to bpf_perf_event_output will fail and return -EFAULT.
+ *
+ * See bpf_xdp_event_output in net/core/filter.c.
+ *
+ * The BPF_F_CURRENT_CPU flag means that the event output fd
+ * will be indexed by the CPU number in the event map.
+ */
+ u64 flags = BPF_F_CURRENT_CPU;
+ u16 sample_size;
+ int ret;
+
+ metadata.cookie = 0xdead;
+ metadata.pkt_len = (u16)(data_end - data);
+ sample_size = min(metadata.pkt_len, SAMPLE_SIZE);
+ flags |= (u64)sample_size << 32;
+
+ ret = bpf_perf_event_output(ctx, &my_map, flags,
+ &metadata, sizeof(metadata));
+ if (ret)
+ bpf_printk("perf_event_output failed: %d\n", ret);
+ }
+
+ return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;