bpf: add bpffs multi-dimensional array tests in test_btf

For multiple dimensional arrays like below,
  int a[2][3]
both llvm and pahole generated one BTF_KIND_ARRAY type like
  . element_type: int
  . index_type: unsigned int
  . number of elements: 6

Such a collapsed BTF_KIND_ARRAY type will cause the divergence
in BTF vs. the user code. In the compile-once-run-everywhere
project, the header file is generated from BTF and used for bpf
program, and the definition in the header file will be different
from what user expects.

But the kernel actually supports chained multi-dimensional array
types properly. The above "int a[2][3]" can be represented as
  Type #n:
    . element_type: int
    . index_type: unsigned int
    . number of elements: 3
  Type #(n+1):
    . element_type: type #n
    . index_type: unsigned int
    . number of elements: 2

The following llvm commit
  https://reviews.llvm.org/rL357215
also enables llvm to generated proper chained multi-dimensional arrays.

The test_btf already has a raw test ("struct test #1") for chained
multi-dimensional arrays. This patch added amended bpffs test for
chained multi-dimensional arrays.
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_btf.c

@@ -3677,6 +3677,7 @@ struct pprint_mapv {
 	} aenum;
 	uint32_t ui32b;
 	uint32_t bits2c:2;
+	uint8_t si8_4[2][2];
 };
 
 #ifdef __SIZEOF_INT128__
@@ -3729,7 +3730,7 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_ENUM_ENC(NAME_TBD, 2),
 		BTF_ENUM_ENC(NAME_TBD, 3),
 		/* struct pprint_mapv */		/* [16] */
-		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 10), 40),
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 11), 40),
 		BTF_MEMBER_ENC(NAME_TBD, 11, 0),	/* uint32_t ui32 */
 		BTF_MEMBER_ENC(NAME_TBD, 10, 32),	/* uint16_t ui16 */
 		BTF_MEMBER_ENC(NAME_TBD, 12, 64),	/* int32_t si32 */
@@ -3740,9 +3741,12 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_MEMBER_ENC(NAME_TBD, 15, 192),	/* aenum */
 		BTF_MEMBER_ENC(NAME_TBD, 11, 224),	/* uint32_t ui32b */
 		BTF_MEMBER_ENC(NAME_TBD, 6, 256),	/* bits2c */
+		BTF_MEMBER_ENC(NAME_TBD, 17, 264),	/* si8_4 */
+		BTF_TYPE_ARRAY_ENC(18, 1, 2),		/* [17] */
+		BTF_TYPE_ARRAY_ENC(1, 1, 2),		/* [18] */
 		BTF_END_RAW,
 	},
-	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c"),
+	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c\0si8_4"),
 	.key_size = sizeof(unsigned int),
 	.value_size = sizeof(struct pprint_mapv),
 	.key_type_id = 3,	/* unsigned int */
@@ -3791,7 +3795,7 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_ENUM_ENC(NAME_TBD, 2),
 		BTF_ENUM_ENC(NAME_TBD, 3),
 		/* struct pprint_mapv */		/* [16] */
-		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 1, 10), 40),
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 1, 11), 40),
 		BTF_MEMBER_ENC(NAME_TBD, 11, BTF_MEMBER_OFFSET(0, 0)),	/* uint32_t ui32 */
 		BTF_MEMBER_ENC(NAME_TBD, 10, BTF_MEMBER_OFFSET(0, 32)),	/* uint16_t ui16 */
 		BTF_MEMBER_ENC(NAME_TBD, 12, BTF_MEMBER_OFFSET(0, 64)),	/* int32_t si32 */
@@ -3802,9 +3806,12 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_MEMBER_ENC(NAME_TBD, 15, BTF_MEMBER_OFFSET(0, 192)),	/* aenum */
 		BTF_MEMBER_ENC(NAME_TBD, 11, BTF_MEMBER_OFFSET(0, 224)),	/* uint32_t ui32b */
 		BTF_MEMBER_ENC(NAME_TBD, 6, BTF_MEMBER_OFFSET(2, 256)),	/* bits2c */
+		BTF_MEMBER_ENC(NAME_TBD, 17, 264),	/* si8_4 */
+		BTF_TYPE_ARRAY_ENC(18, 1, 2),		/* [17] */
+		BTF_TYPE_ARRAY_ENC(1, 1, 2),		/* [18] */
 		BTF_END_RAW,
 	},
-	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c"),
+	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c\0si8_4"),
 	.key_size = sizeof(unsigned int),
 	.value_size = sizeof(struct pprint_mapv),
 	.key_type_id = 3,	/* unsigned int */
@@ -3855,7 +3862,7 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_ENUM_ENC(NAME_TBD, 2),
 		BTF_ENUM_ENC(NAME_TBD, 3),
 		/* struct pprint_mapv */		/* [16] */
-		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 1, 10), 40),
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 1, 11), 40),
 		BTF_MEMBER_ENC(NAME_TBD, 11, BTF_MEMBER_OFFSET(0, 0)),	/* uint32_t ui32 */
 		BTF_MEMBER_ENC(NAME_TBD, 10, BTF_MEMBER_OFFSET(0, 32)),	/* uint16_t ui16 */
 		BTF_MEMBER_ENC(NAME_TBD, 12, BTF_MEMBER_OFFSET(0, 64)),	/* int32_t si32 */
@@ -3866,13 +3873,16 @@ static struct btf_raw_test pprint_test_template[] = {
 		BTF_MEMBER_ENC(NAME_TBD, 15, BTF_MEMBER_OFFSET(0, 192)),	/* aenum */
 		BTF_MEMBER_ENC(NAME_TBD, 11, BTF_MEMBER_OFFSET(0, 224)),	/* uint32_t ui32b */
 		BTF_MEMBER_ENC(NAME_TBD, 17, BTF_MEMBER_OFFSET(2, 256)),	/* bits2c */
+		BTF_MEMBER_ENC(NAME_TBD, 20, BTF_MEMBER_OFFSET(0, 264)),	/* si8_4 */
 		/* typedef unsigned int ___int */	/* [17] */
 		BTF_TYPEDEF_ENC(NAME_TBD, 18),
 		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_VOLATILE, 0, 0), 6),	/* [18] */
 		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 15),	/* [19] */
+		BTF_TYPE_ARRAY_ENC(21, 1, 2),					/* [20] */
+		BTF_TYPE_ARRAY_ENC(1, 1, 2),					/* [21] */
 		BTF_END_RAW,
 	},
-	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c\0___int"),
+	BTF_STR_SEC("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum\0ui32b\0bits2c\0___int\0si8_4"),
 	.key_size = sizeof(unsigned int),
 	.value_size = sizeof(struct pprint_mapv),
 	.key_type_id = 3,	/* unsigned int */
@@ -4007,6 +4017,10 @@ static void set_pprint_mapv(enum pprint_mapv_kind_t mapv_kind,
 			v->aenum = i & 0x03;
 			v->ui32b = 4;
 			v->bits2c = 1;
+			v->si8_4[0][0] = (cpu + i) & 0xff;
+			v->si8_4[0][1] = (cpu + i + 1) & 0xff;
+			v->si8_4[1][0] = (cpu + i + 2) & 0xff;
+			v->si8_4[1][1] = (cpu + i + 3) & 0xff;
 			v = (void *)v + rounded_value_size;
 		}
 	}
@@ -4040,7 +4054,7 @@ ssize_t get_pprint_expected_line(enum pprint_mapv_kind_t mapv_kind,
 		nexpected_line = snprintf(expected_line, line_size,
 					  "%s%u: {%u,0,%d,0x%x,0x%x,0x%x,"
 					  "{%lu|[%u,%u,%u,%u,%u,%u,%u,%u]},%s,"
-					  "%u,0x%x}\n",
+					  "%u,0x%x,[[%d,%d],[%d,%d]]}\n",
 					  percpu_map ? "\tcpu" : "",
 					  percpu_map ? cpu : next_key,
 					  v->ui32, v->si32,
@@ -4054,7 +4068,9 @@ ssize_t get_pprint_expected_line(enum pprint_mapv_kind_t mapv_kind,
 					  v->ui8a[6], v->ui8a[7],
 					  pprint_enum_str[v->aenum],
 					  v->ui32b,
-					  v->bits2c);
+					  v->bits2c,
+					  v->si8_4[0][0], v->si8_4[0][1],
+					  v->si8_4[1][0], v->si8_4[1][1]);
 	}
 
 #ifdef __SIZEOF_INT128__