selftests/bpf: add btf_dump BTF-to-C conversion tests

Add new test_btf_dump set of tests, validating BTF-to-C conversion
correctness. Tests rely on clang to generate BTF from provided C test
cases.

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

1 files changed, 111 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/btf_dump_test_case_padding.c b/tools/testing/selftests/bpf/progs/btf_dump_test_case_padding.c
new file mode 100644
index 000000000000..3a62119c7498
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf_dump_test_case_padding.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * BTF-to-C dumper tests for implicit and explicit padding between fields and
+ * at the end of a struct.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+/* ----- START-EXPECTED-OUTPUT ----- */
+struct padded_implicitly {
+	int a;
+	long int b;
+	char c;
+};
+
+/* ------ END-EXPECTED-OUTPUT ------ */
+
+/* ----- START-EXPECTED-OUTPUT ----- */
+/*
+ *struct padded_explicitly {
+ *	int a;
+ *	int: 32;
+ *	int b;
+ *};
+ *
+ */
+/* ------ END-EXPECTED-OUTPUT ------ */
+
+struct padded_explicitly {
+	int a;
+	int: 1; /* algo will explicitly pad with full 32 bits here */
+	int b;
+};
+
+/* ----- START-EXPECTED-OUTPUT ----- */
+/*
+ *struct padded_a_lot {
+ *	int a;
+ *	long: 32;
+ *	long: 64;
+ *	long: 64;
+ *	int b;
+ *};
+ *
+ */
+/* ------ END-EXPECTED-OUTPUT ------ */
+
+struct padded_a_lot {
+	int a;
+	/* 32 bit of implicit padding here, which algo will make explicit */
+	long: 64;
+	long: 64;
+	int b;
+};
+
+/* ----- START-EXPECTED-OUTPUT ----- */
+/*
+ *struct padded_cache_line {
+ *	int a;
+ *	long: 32;
+ *	long: 64;
+ *	long: 64;
+ *	long: 64;
+ *	int b;
+ *};
+ *
+ */
+/* ------ END-EXPECTED-OUTPUT ------ */
+
+struct padded_cache_line {
+	int a;
+	int b __attribute__((aligned(32)));
+};
+
+/* ----- START-EXPECTED-OUTPUT ----- */
+/*
+ *struct zone_padding {
+ *	char x[0];
+ *};
+ *
+ *struct zone {
+ *	int a;
+ *	short b;
+ *	short: 16;
+ *	struct zone_padding __pad__;
+ *};
+ *
+ */
+/* ------ END-EXPECTED-OUTPUT ------ */
+
+struct zone_padding {
+	char x[0];
+} __attribute__((__aligned__(8)));
+
+struct zone {
+	int a;
+	short b;
+	short: 16;
+	struct zone_padding __pad__;
+};
+
+int f(struct {
+	struct padded_implicitly _1;
+	struct padded_explicitly _2;
+	struct padded_a_lot _3;
+	struct padded_cache_line _4;
+	struct zone _5;
+} *_)
+{
+	return 0;
+}