bpf: fix byte order test in test_verifier

We really must check with #if __BYTE_ORDER == XYZ instead of
just presence of #ifdef __LITTLE_ENDIAN. I noticed that when
actually running this on big endian machine, the latter test
resolves to true for user space, same for #ifdef __BIG_ENDIAN.

E.g., looking at endian.h from libc, both are also defined
there, so we really must test this against __BYTE_ORDER instead
for proper insns selection. For the kernel, such checks are
fine though e.g. see 13da9e20 ("Revert "endian: #define
__BYTE_ORDER"") and 415586c9 ("UAPI: fix endianness conditionals
in M32R's asm/stat.h") for some more context, but not for
user space. Lets also make sure to properly include endian.h.
After that, suite passes for me:

./test_verifier: ELF 64-bit MSB executable, [...]

Linux foo 4.13.0-rc3+ #4 SMP Fri Aug 4 06:59:30 EDT 2017 s390x s390x s390x GNU/Linux

Before fix: Summary: 505 PASSED, 11 FAILED
After  fix: Summary: 516 PASSED,  0 FAILED

Fixes: 18f3d6be ("selftests/bpf: Add test cases to test narrower ctx field loads")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -8,6 +8,7 @@
  * License as published by the Free Software Foundation.
  */
 
+#include <endian.h>
 #include <asm/types.h>
 #include <linux/types.h>
 #include <stdint.h>
@@ -1098,7 +1099,7 @@ static struct bpf_test tests[] = {
 		"check skb->hash byte load permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash)),
 #else
@@ -1135,7 +1136,7 @@ static struct bpf_test tests[] = {
 		"check skb->hash byte load not permitted 3",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash) + 3),
 #else
@@ -1244,7 +1245,7 @@ static struct bpf_test tests[] = {
 		"check skb->hash half load permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash)),
 #else
@@ -1259,7 +1260,7 @@ static struct bpf_test tests[] = {
 		"check skb->hash half load not permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash) + 2),
 #else
@@ -5422,7 +5423,7 @@ static struct bpf_test tests[] = {
 		"check bpf_perf_event_data->sample_period byte load permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct bpf_perf_event_data, sample_period)),
 #else
@@ -5438,7 +5439,7 @@ static struct bpf_test tests[] = {
 		"check bpf_perf_event_data->sample_period half load permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct bpf_perf_event_data, sample_period)),
 #else
@@ -5454,7 +5455,7 @@ static struct bpf_test tests[] = {
 		"check bpf_perf_event_data->sample_period word load permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct bpf_perf_event_data, sample_period)),
 #else
@@ -5481,7 +5482,7 @@ static struct bpf_test tests[] = {
 		"check skb->data half load not permitted",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, data)),
 #else
@@ -5497,7 +5498,7 @@ static struct bpf_test tests[] = {
 		"check skb->tc_classid half load not permitted for lwt prog",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
-#ifdef __LITTLE_ENDIAN
+#if __BYTE_ORDER == __LITTLE_ENDIAN
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, tc_classid)),
 #else