selftests/bpf: add CO-RE relocs struct flavors tests

Add tests verifying that BPF program can use various struct/union
"flavors" to extract data from the same target struct/union.

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, 62 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_flavors.c b/tools/testing/selftests/bpf/progs/test_core_reloc_flavors.c
new file mode 100644
index 000000000000..9fda73e87972
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_flavors.c
@@ -0,0 +1,62 @@
+// 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_flavors {
+	int a;
+	int b;
+	int c;
+};
+
+/* local flavor with reversed layout */
+struct core_reloc_flavors___reversed {
+	int c;
+	int b;
+	int a;
+};
+
+/* local flavor with nested/overlapping layout */
+struct core_reloc_flavors___weird {
+	struct {
+		int b;
+	};
+	/* a and c overlap in local flavor, but this should still work
+	 * correctly with target original flavor
+	 */
+	union {
+		int a;
+		int c;
+	};
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_flavors(void *ctx)
+{
+	struct core_reloc_flavors *in_orig = (void *)&data.in;
+	struct core_reloc_flavors___reversed *in_rev = (void *)&data.in;
+	struct core_reloc_flavors___weird *in_weird = (void *)&data.in;
+	struct core_reloc_flavors *out = (void *)&data.out;
+
+	/* read a using weird layout */
+	if (BPF_CORE_READ(&out->a, &in_weird->a))
+		return 1;
+	/* read b using reversed layout */
+	if (BPF_CORE_READ(&out->b, &in_rev->b))
+		return 1;
+	/* read c using original layout */
+	if (BPF_CORE_READ(&out->c, &in_orig->c))
+		return 1;
+
+	return 0;
+}
+