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1// SPDX-License-Identifier: GPL-2.02/* Copyright Leon Hwang */3 4#include <linux/bpf.h>5#include <bpf/bpf_helpers.h>6 7#define ERRMSG_LEN 648 9struct xdp_errmsg {10 char msg[ERRMSG_LEN];11};12 13struct {14 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);15 __type(key, int);16 __type(value, int);17} xdp_errmsg_pb SEC(".maps");18 19struct xdp_attach_error_ctx {20 unsigned long unused;21 22 /*23 * bpf does not support tracepoint __data_loc directly.24 *25 * Actually, this field is a 32 bit integer whose value encodes26 * information on where to find the actual data. The first 2 bytes is27 * the size of the data. The last 2 bytes is the offset from the start28 * of the tracepoint struct where the data begins.29 * -- https://github.com/iovisor/bpftrace/pull/154230 */31 __u32 msg; // __data_loc char[] msg;32};33 34/*35 * Catch the error message at the tracepoint.36 */37 38SEC("tp/xdp/bpf_xdp_link_attach_failed")39int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx)40{41 char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg);42 struct xdp_errmsg errmsg = {};43 44 bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg);45 bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg,46 ERRMSG_LEN);47 return 0;48}49 50/*51 * Reuse the XDP program in xdp_dummy.c.52 */53 54char LICENSE[] SEC("license") = "GPL";55