selftests/bpf: Add testcase for async callback return value failure

A previous commit updated the verifier to print an accurate failure
message for when someone specifies a nonzero return value from an async
callback. This adds a testcase for validating that the verifier emits
the correct message in such a case.

Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231009161414.235829-2-void@manifault.com

1 files changed, 47 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/timer_failure.c b/tools/testing/selftests/bpf/progs/timer_failure.c
new file mode 100644
index 000000000000..226d33b5a05c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/timer_failure.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <time.h>
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_tcp_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct elem {
+	struct bpf_timer t;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__type(value, struct elem);
+} timer_map SEC(".maps");
+
+static int timer_cb_ret1(void *map, int *key, struct bpf_timer *timer)
+{
+	if (bpf_get_smp_processor_id() % 2)
+		return 1;
+	else
+		return 0;
+}
+
+SEC("fentry/bpf_fentry_test1")
+__failure __msg("should have been in (0x0; 0x0)")
+int BPF_PROG2(test_ret_1, int, a)
+{
+	int key = 0;
+	struct bpf_timer *timer;
+
+	timer = bpf_map_lookup_elem(&timer_map, &key);
+	if (timer) {
+		bpf_timer_init(timer, &timer_map, CLOCK_BOOTTIME);
+		bpf_timer_set_callback(timer, timer_cb_ret1);
+		bpf_timer_start(timer, 1000, 0);
+	}
+
+	return 0;
+}