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// 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";
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