samples/bpf: fix a build issue

With latest net-next:

====
clang  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/6.3.1/include -I./arch/x86/include -I./arch/x86/include/generated/uapi -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h  -Isamples/bpf \
    -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
    -Wno-compare-distinct-pointer-types \
    -Wno-gnu-variable-sized-type-not-at-end \
    -Wno-address-of-packed-member -Wno-tautological-compare \
    -Wno-unknown-warning-option \
    -O2 -emit-llvm -c samples/bpf/tcp_synrto_kern.c -o -| llc -march=bpf -filetype=obj -o samples/bpf/tcp_synrto_kern.o
samples/bpf/tcp_synrto_kern.c:20:10: fatal error: 'bpf_endian.h' file not found
          ^~~~~~~~~~~~~~
1 error generated.
====

net has the same issue.

Add support for ntohl and htonl in tools/testing/selftests/bpf/bpf_endian.h.
Also move bpf_helpers.h from samples/bpf to selftests/bpf and change
compiler include logic so that programs in samples/bpf can access the headers
in selftests/bpf, but not the other way around.

Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 15 insertions, 1 deletions

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 9c650589e80f..87246be6feb8 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -207,6 +207,7 @@ $(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h
 # useless for BPF samples.
 $(obj)/%.o: $(src)/%.c
         $(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) -I$(obj) \
+                -I$(srctree)/tools/testing/selftests/bpf/ \
                 -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
                 -Wno-compare-distinct-pointer-types \
                 -Wno-gnu-variable-sized-type-not-at-end \
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 2ca51a8a588c..153c3a181a4c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -37,6 +37,5 @@ CLANG ?= clang
 
 %.o: %.c
         $(CLANG) -I. -I./include/uapi -I../../../include/uapi \
-                -I../../../../samples/bpf/ \
                 -Wno-compare-distinct-pointer-types \
                 -O2 -target bpf -c $< -o $@
diff --git a/tools/testing/selftests/bpf/bpf_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index 487cbfb89beb..74af266aa512 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -23,11 +23,19 @@
 # define __bpf_htons(x)                 __builtin_bswap16(x)
 # define __bpf_constant_ntohs(x)        ___constant_swab16(x)
 # define __bpf_constant_htons(x)        ___constant_swab16(x)
+# define __bpf_ntohl(x)                 __builtin_bswap32(x)
+# define __bpf_htonl(x)                 __builtin_bswap32(x)
+# define __bpf_constant_ntohl(x)        ___constant_swab32(x)
+# define __bpf_constant_htonl(x)        ___constant_swab32(x)
 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 # define __bpf_ntohs(x)                 (x)
 # define __bpf_htons(x)                 (x)
 # define __bpf_constant_ntohs(x)        (x)
 # define __bpf_constant_htons(x)        (x)
+# define __bpf_ntohl(x)                 (x)
+# define __bpf_htonl(x)                 (x)
+# define __bpf_constant_ntohl(x)        (x)
+# define __bpf_constant_htonl(x)        (x)
 #else
 # error "Fix your compiler's __BYTE_ORDER__?!"
 #endif
@@ -38,5 +46,11 @@
 #define bpf_ntohs(x)                            \
         (__builtin_constant_p(x) ?              \
          __bpf_constant_ntohs(x) : __bpf_ntohs(x))
+#define bpf_htonl(x)                            \
+        (__builtin_constant_p(x) ?              \
+         __bpf_constant_htonl(x) : __bpf_htonl(x))
+#define bpf_ntohl(x)                            \
+        (__builtin_constant_p(x) ?              \
+         __bpf_constant_ntohl(x) : __bpf_ntohl(x))
 
 #endif /* __BPF_ENDIAN__ */
diff --git a/samples/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index d50ac342dc92..d50ac342dc92 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h