[RFC bpf-next 10/15] selftests/bpf: BTF distill tests to ensure LOC[_PARAM|_PROTO] add to split BTF

[Alan Maguire <alan.maguire@oracle.com>]

When creating distilled BTF, BTF_KIND_LOC_PARAM and BTF_KIND_LOC_PROTO
should be added to split BTF.  This means potentially some duplication
of location information, but only for out-of-tree modules that use
distilled base/split BTF.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 .../selftests/bpf/prog_tests/btf_distill.c    | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_distill.c b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
index fb67ae195a73..1dd26ec79b69 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_distill.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
@@ -671,6 +671,72 @@ static void test_distilled_base_embedded_err(void)
 	btf__free(btf1);
 }
 
+/* LOC_PARAM, LOC_PROTO should be added to split BTF. */
+static void test_distilled_loc(void)
+{
+	struct btf *btf1 = NULL, *btf2 = NULL, *btf3 = NULL, *btf4 = NULL;
+
+	btf1 = btf__new_empty();
+	if (!ASSERT_OK_PTR(btf1, "empty_main_btf"))
+		return;
+
+	btf__add_int(btf1, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_func_proto(btf1, 1);                   /* [2] int (*)(int); */
+	btf__add_func_param(btf1, "p1", 1);
+	btf__add_loc_param(btf1, -4, true, -1, 0, 0, 0);/* [3] loc value */
+
+	VALIDATE_RAW_BTF(
+		btf1,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p1' type_id=1",
+		"[3] LOC_PARAM '(anon)' size=-4 value=-1");
+
+	btf2 = btf__new_empty_split(btf1);
+	if (!ASSERT_OK_PTR(btf2, "empty_split_btf"))
+		goto cleanup;
+
+	btf__add_loc_proto(btf2);			/* [4] loc proto */
+	btf__add_loc_proto_param(btf2, 3);		/*  param value */
+
+	btf__add_locsec(btf2, ".locs");			/* [5] locsec */
+	btf__add_locsec_loc(btf2, "foo", 2, 4, 256);	/* "foo" offset 256 */
+	VALIDATE_RAW_BTF(
+		btf2,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p1' type_id=1",
+		"[3] LOC_PARAM '(anon)' size=-4 value=-1",
+		"[4] LOC_PROTO '(anon)' vlen=1\n"
+		"\ttype_id=3",
+		"[5] LOCSEC '.locs' vlen=1\n"
+		"\t'foo' func_proto_type_id=2 loc_proto_type_id=4 offset=256");
+
+	if (!ASSERT_EQ(0, btf__distill_base(btf2, &btf3, &btf4),
+		       "distilled_base") ||
+	    !ASSERT_OK_PTR(btf3, "distilled_base") ||
+	    !ASSERT_OK_PTR(btf4, "distilled_split") ||
+	    !ASSERT_EQ(2, btf__type_cnt(btf3), "distilled_base_type_cnt"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		btf4,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		/* remainder is split BTF */
+		"[2] LOC_PROTO '(anon)' vlen=1\n"
+		"\ttype_id=5",
+		"[3] LOCSEC '.locs' vlen=1\n"
+		"\t'foo' func_proto_type_id=4 loc_proto_type_id=2 offset=256",
+		"[4] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p1' type_id=1",
+		"[5] LOC_PARAM '(anon)' size=-4 value=-1");
+cleanup:
+	btf__free(btf4);
+	btf__free(btf3);
+	btf__free(btf2);
+	btf__free(btf1);
+}
+
 void test_btf_distill(void)
 {
 	if (test__start_subtest("distilled_base"))
@@ -689,4 +755,6 @@ void test_btf_distill(void)
 		test_distilled_base_vmlinux();
 	if (test__start_subtest("distilled_endianness"))
 		test_distilled_endianness();
+	if (test__start_subtest("distilled_loc"))
+		test_distilled_loc();
 }
-- 
2.39.3