tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
selftests/bpf: Add testcase for xdp attaching failure tracepoint
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>
authored by
Leon Hwang
and committed by
Alexei Starovoitov
7fedbf32
bf4ea1d0
+119
+65
tools/testing/selftests/bpf/prog_tests/xdp_attach.c
+65
tools/testing/selftests/bpf/prog_tests/xdp_attach.c
···
1
1
// SPDX-License-Identifier: GPL-2.0
2
2
#include <test_progs.h>
3
+
#include "test_xdp_attach_fail.skel.h"
3
4
4
5
#define IFINDEX_LO 1
5
6
#define XDP_FLAGS_REPLACE (1U << 4)
···
86
85
bpf_object__close(obj1);
87
86
}
88
87
88
+
#define ERRMSG_LEN 64
89
+
90
+
struct xdp_errmsg {
91
+
char msg[ERRMSG_LEN];
92
+
};
93
+
94
+
static void on_xdp_errmsg(void *ctx, int cpu, void *data, __u32 size)
95
+
{
96
+
struct xdp_errmsg *ctx_errmg = ctx, *tp_errmsg = data;
97
+
98
+
memcpy(&ctx_errmg->msg, &tp_errmsg->msg, ERRMSG_LEN);
99
+
}
100
+
101
+
static const char tgt_errmsg[] = "Invalid XDP flags for BPF link attachment";
102
+
103
+
static void test_xdp_attach_fail(const char *file)
104
+
{
105
+
struct test_xdp_attach_fail *skel = NULL;
106
+
struct xdp_errmsg errmsg = {};
107
+
struct perf_buffer *pb = NULL;
108
+
struct bpf_object *obj = NULL;
109
+
int err, fd_xdp;
110
+
111
+
LIBBPF_OPTS(bpf_link_create_opts, opts);
112
+
113
+
skel = test_xdp_attach_fail__open_and_load();
114
+
if (!ASSERT_OK_PTR(skel, "test_xdp_attach_fail__open_and_load"))
115
+
goto out_close;
116
+
117
+
err = test_xdp_attach_fail__attach(skel);
118
+
if (!ASSERT_EQ(err, 0, "test_xdp_attach_fail__attach"))
119
+
goto out_close;
120
+
121
+
/* set up perf buffer */
122
+
pb = perf_buffer__new(bpf_map__fd(skel->maps.xdp_errmsg_pb), 1,
123
+
on_xdp_errmsg, NULL, &errmsg, NULL);
124
+
if (!ASSERT_OK_PTR(pb, "perf_buffer__new"))
125
+
goto out_close;
126
+
127
+
err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &fd_xdp);
128
+
if (!ASSERT_EQ(err, 0, "bpf_prog_test_load"))
129
+
goto out_close;
130
+
131
+
opts.flags = 0xFF; // invalid flags to fail to attach XDP prog
132
+
err = bpf_link_create(fd_xdp, IFINDEX_LO, BPF_XDP, &opts);
133
+
if (!ASSERT_EQ(err, -EINVAL, "bpf_link_create"))
134
+
goto out_close;
135
+
136
+
/* read perf buffer */
137
+
err = perf_buffer__poll(pb, 100);
138
+
if (!ASSERT_GT(err, -1, "perf_buffer__poll"))
139
+
goto out_close;
140
+
141
+
ASSERT_STRNEQ((const char *) errmsg.msg, tgt_errmsg,
142
+
42 /* strlen(tgt_errmsg) */, "check error message");
143
+
144
+
out_close:
145
+
perf_buffer__free(pb);
146
+
bpf_object__close(obj);
147
+
test_xdp_attach_fail__destroy(skel);
148
+
}
149
+
89
150
void serial_test_xdp_attach(void)
90
151
{
91
152
if (test__start_subtest("xdp_attach"))
92
153
test_xdp_attach("./test_xdp.bpf.o");
93
154
if (test__start_subtest("xdp_attach_dynptr"))
94
155
test_xdp_attach("./test_xdp_dynptr.bpf.o");
156
+
if (test__start_subtest("xdp_attach_failed"))
157
+
test_xdp_attach_fail("./xdp_dummy.bpf.o");
95
158
}
+54
tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c
+54
tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c
···
1
+
// SPDX-License-Identifier: GPL-2.0
2
+
/* Copyright Leon Hwang */
3
+
4
+
#include <linux/bpf.h>
5
+
#include <bpf/bpf_helpers.h>
6
+
7
+
#define ERRMSG_LEN 64
8
+
9
+
struct xdp_errmsg {
10
+
char msg[ERRMSG_LEN];
11
+
};
12
+
13
+
struct {
14
+
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
15
+
__type(key, int);
16
+
__type(value, int);
17
+
} xdp_errmsg_pb SEC(".maps");
18
+
19
+
struct 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 encodes
26
+
* information on where to find the actual data. The first 2 bytes is
27
+
* the size of the data. The last 2 bytes is the offset from the start
28
+
* of the tracepoint struct where the data begins.
29
+
* -- https://github.com/iovisor/bpftrace/pull/1542
30
+
*/
31
+
__u32 msg; // __data_loc char[] msg;
32
+
};
33
+
34
+
/*
35
+
* Catch the error message at the tracepoint.
36
+
*/
37
+
38
+
SEC("tp/xdp/bpf_xdp_link_attach_failed")
39
+
int 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
+
54
+
char LICENSE[] SEC("license") = "GPL";