1*7fedbf32SLeon Hwang // SPDX-License-Identifier: GPL-2.0
2*7fedbf32SLeon Hwang /* Copyright Leon Hwang */
3*7fedbf32SLeon Hwang
4*7fedbf32SLeon Hwang #include <linux/bpf.h>
5*7fedbf32SLeon Hwang #include <bpf/bpf_helpers.h>
6*7fedbf32SLeon Hwang
7*7fedbf32SLeon Hwang #define ERRMSG_LEN 64
8*7fedbf32SLeon Hwang
9*7fedbf32SLeon Hwang struct xdp_errmsg {
10*7fedbf32SLeon Hwang char msg[ERRMSG_LEN];
11*7fedbf32SLeon Hwang };
12*7fedbf32SLeon Hwang
13*7fedbf32SLeon Hwang struct {
14*7fedbf32SLeon Hwang __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
15*7fedbf32SLeon Hwang __type(key, int);
16*7fedbf32SLeon Hwang __type(value, int);
17*7fedbf32SLeon Hwang } xdp_errmsg_pb SEC(".maps");
18*7fedbf32SLeon Hwang
19*7fedbf32SLeon Hwang struct xdp_attach_error_ctx {
20*7fedbf32SLeon Hwang unsigned long unused;
21*7fedbf32SLeon Hwang
22*7fedbf32SLeon Hwang /*
23*7fedbf32SLeon Hwang * bpf does not support tracepoint __data_loc directly.
24*7fedbf32SLeon Hwang *
25*7fedbf32SLeon Hwang * Actually, this field is a 32 bit integer whose value encodes
26*7fedbf32SLeon Hwang * information on where to find the actual data. The first 2 bytes is
27*7fedbf32SLeon Hwang * the size of the data. The last 2 bytes is the offset from the start
28*7fedbf32SLeon Hwang * of the tracepoint struct where the data begins.
29*7fedbf32SLeon Hwang * -- https://github.com/iovisor/bpftrace/pull/1542
30*7fedbf32SLeon Hwang */
31*7fedbf32SLeon Hwang __u32 msg; // __data_loc char[] msg;
32*7fedbf32SLeon Hwang };
33*7fedbf32SLeon Hwang
34*7fedbf32SLeon Hwang /*
35*7fedbf32SLeon Hwang * Catch the error message at the tracepoint.
36*7fedbf32SLeon Hwang */
37*7fedbf32SLeon Hwang
38*7fedbf32SLeon Hwang SEC("tp/xdp/bpf_xdp_link_attach_failed")
tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx * ctx)39*7fedbf32SLeon Hwang int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx)
40*7fedbf32SLeon Hwang {
41*7fedbf32SLeon Hwang char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg);
42*7fedbf32SLeon Hwang struct xdp_errmsg errmsg = {};
43*7fedbf32SLeon Hwang
44*7fedbf32SLeon Hwang bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg);
45*7fedbf32SLeon Hwang bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg,
46*7fedbf32SLeon Hwang ERRMSG_LEN);
47*7fedbf32SLeon Hwang return 0;
48*7fedbf32SLeon Hwang }
49*7fedbf32SLeon Hwang
50*7fedbf32SLeon Hwang /*
51*7fedbf32SLeon Hwang * Reuse the XDP program in xdp_dummy.c.
52*7fedbf32SLeon Hwang */
53*7fedbf32SLeon Hwang
54*7fedbf32SLeon Hwang char LICENSE[] SEC("license") = "GPL";
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