selftests/bpf: add CO-RE relocs nesting tests

Add a bunch of test validating correct handling of nested
structs/unions.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_nesting.c b/tools/testing/selftests/bpf/progs/test_core_reloc_nesting.c
new file mode 100644
index 000000000000..3ca30cec2b39
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_nesting.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+static volatile struct data {
+	char in[256];
+	char out[256];
+} data;
+
+struct core_reloc_nesting_substruct {
+	int a;
+};
+
+union core_reloc_nesting_subunion {
+	int b;
+};
+
+/* int a.a.a and b.b.b accesses */
+struct core_reloc_nesting {
+	union {
+		struct core_reloc_nesting_substruct a;
+	} a;
+	struct {
+		union core_reloc_nesting_subunion b;
+	} b;
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_nesting(void *ctx)
+{
+	struct core_reloc_nesting *in = (void *)&data.in;
+	struct core_reloc_nesting *out = (void *)&data.out;
+
+	if (BPF_CORE_READ(&out->a.a.a, &in->a.a.a))
+		return 1;
+	if (BPF_CORE_READ(&out->b.b.b, &in->b.b.b))
+		return 1;
+
+	return 0;
+}
+