selftests/bpf: Add test for __nullable suffix in tp_btf

Add a tracepoint with __nullable suffix in bpf_testmod, and add cases
for it:

$ ./test_progs -t "tp_btf_nullable"
 #406/1   tp_btf_nullable/handle_tp_btf_nullable_bare1:OK
 #406/2   tp_btf_nullable/handle_tp_btf_nullable_bare2:OK
 #406     tp_btf_nullable:OK
 Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240911033719.91468-3-lulie@linux.alibaba.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_tp_btf_nullable.c b/tools/testing/selftests/bpf/progs/test_tp_btf_nullable.c
new file mode 100644
index 000000000000..bba3e37f749b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_tp_btf_nullable.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+#include "bpf_misc.h"
+
+SEC("tp_btf/bpf_testmod_test_nullable_bare")
+__failure __msg("R1 invalid mem access 'trusted_ptr_or_null_'")
+int BPF_PROG(handle_tp_btf_nullable_bare1, struct bpf_testmod_test_read_ctx *nullable_ctx)
+{
+	return nullable_ctx->len;
+}
+
+SEC("tp_btf/bpf_testmod_test_nullable_bare")
+int BPF_PROG(handle_tp_btf_nullable_bare2, struct bpf_testmod_test_read_ctx *nullable_ctx)
+{
+	if (nullable_ctx)
+		return nullable_ctx->len;
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";