selftests/bpf: Add BTF_KIND_ENUM64 unit tests

Add unit tests for basic BTF_KIND_ENUM64 encoding.

Acked-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Yonghong Song <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/prog_tests/btf.c

···
 	.btf_load_err = true,
 	.err_str = "Type tags don't precede modifiers",
 },
+{
+	.descr = "enum64 test #1, unsigned, size 8",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),			/* [1] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 2), 8),	/* [2] */
+		BTF_ENUM64_ENC(NAME_TBD, 0, 0),
+		BTF_ENUM64_ENC(NAME_TBD, 1, 1),
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0a\0b\0c"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "tag_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 8,
+	.key_type_id = 1,
+	.value_type_id = 2,
+	.max_entries = 1,
+},
+{
+	.descr = "enum64 test #2, signed, size 4",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),			/* [1] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM64, 1, 2), 4),	/* [2] */
+		BTF_ENUM64_ENC(NAME_TBD, -1, 0),
+		BTF_ENUM64_ENC(NAME_TBD, 1, 0),
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0a\0b\0c"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "tag_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 4,
+	.key_type_id = 1,
+	.value_type_id = 2,
+	.max_entries = 1,
+},
 
 }; /* struct btf_raw_test raw_tests[] */
 

tools/testing/selftests/bpf/test_btf.h

···
 #define BTF_MEMBER_ENC(name, type, bits_offset)	\
 	(name), (type), (bits_offset)
 #define BTF_ENUM_ENC(name, val) (name), (val)
+#define BTF_ENUM64_ENC(name, val_lo32, val_hi32) (name), (val_lo32), (val_hi32)
 #define BTF_MEMBER_OFFSET(bitfield_size, bits_offset) \
 	((bitfield_size) << 24 | (bits_offset))