// SPDX-License-Identifier: GPL-2.0 /* Copyright Leon Hwang */ #include <linux/bpf.h> #include <bpf/bpf_helpers.h> #define ERRMSG_LEN 64 struct xdp_errmsg { char msg[ERRMSG_LEN]; }; struct { __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); __type(key, int); __type(value, int); } xdp_errmsg_pb SEC(".maps"); struct xdp_attach_error_ctx { unsigned long unused; /* * bpf does not support tracepoint __data_loc directly. * * Actually, this field is a 32 bit integer whose value encodes * information on where to find the actual data. The first 2 bytes is * the size of the data. The last 2 bytes is the offset from the start * of the tracepoint struct where the data begins. * -- https://github.com/iovisor/bpftrace/pull/1542 */ __u32 msg; // __data_loc char[] msg; }; /* * Catch the error message at the tracepoint. */ SEC("tp/xdp/bpf_xdp_link_attach_failed") int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx) { char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg); struct xdp_errmsg errmsg = {}; bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg); bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg, ERRMSG_LEN); return 0; } /* * Reuse the XDP program in xdp_dummy.c. */ char LICENSE[] SEC("license") = "GPL";