7fedbf32fc
Add a test case for the tracepoint of xdp attaching failure by bpf tracepoint when attach XDP to a device with invalid flags option. The bpf tracepoint retrieves error message from the tracepoint, and then put the error message to a perf buffer. The testing code receives error message from perf buffer, and then ASSERT "Invalid XDP flags for BPF link attachment". Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> Link: https://lore.kernel.org/r/20230801142621.7925-3-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
54 lines
1.3 KiB
C
54 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright Leon Hwang */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#define ERRMSG_LEN 64
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struct xdp_errmsg {
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char msg[ERRMSG_LEN];
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};
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__type(key, int);
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__type(value, int);
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} xdp_errmsg_pb SEC(".maps");
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struct xdp_attach_error_ctx {
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unsigned long unused;
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/*
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* bpf does not support tracepoint __data_loc directly.
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*
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* Actually, this field is a 32 bit integer whose value encodes
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* information on where to find the actual data. The first 2 bytes is
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* the size of the data. The last 2 bytes is the offset from the start
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* of the tracepoint struct where the data begins.
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* -- https://github.com/iovisor/bpftrace/pull/1542
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*/
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__u32 msg; // __data_loc char[] msg;
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};
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/*
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* Catch the error message at the tracepoint.
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*/
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SEC("tp/xdp/bpf_xdp_link_attach_failed")
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int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx)
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{
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char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg);
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struct xdp_errmsg errmsg = {};
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bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg);
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bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg,
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ERRMSG_LEN);
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return 0;
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}
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/*
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* Reuse the XDP program in xdp_dummy.c.
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*/
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char LICENSE[] SEC("license") = "GPL";
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