[PATCH bpf-next v2] selftest/bpf: Use -m{little,big}-endian for clang

[PATCH bpf-next v2] selftest/bpf: Use -m{little,big}-endian for clang

[Ilya Leoshkevich]

When cross-compiling tests from x86 to s390, the resulting BPF objects
fail to load due to endianness mismatch.

Fix by using BPF-GCC endianness check for clang as well.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
---
v1 -> v2: Put $(MENDIAN) closer to related options.

tools/testing/selftests/bpf/Makefile | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 933f39381039..3209c208f3b3 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -131,8 +131,13 @@ $(shell $(1) -v -E - </dev/null 2>&1 \
 	| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }')
 endef
 
+# Determine target endianness.
+IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - </dev/null | \
+			grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__')
+MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
+
 CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
-BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) 				\
+BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) 			\
 	     -I. -I./include/uapi -I$(APIDIR)				\
 	     -I$(BPFDIR) -I$(abspath $(OUTPUT)/../usr/include)
 
@@ -271,12 +276,8 @@ $(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))
 
 # Define test_progs BPF-GCC-flavored test runner.
 ifneq ($(BPF_GCC),)
-IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - </dev/null | \
-			grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__')
-MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
-
 TRUNNER_BPF_BUILD_RULE := GCC_BPF_BUILD_RULE
-TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(call get_sys_includes,gcc) $(MENDIAN)
+TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(call get_sys_includes,gcc)
 TRUNNER_BPF_LDFLAGS :=
 $(eval $(call DEFINE_TEST_RUNNER,test_progs,bpf_gcc))
 endif
-- 
2.23.0

Re: [PATCH bpf-next v2] selftest/bpf: Use -m{little,big}-endian for clang

[Daniel Borkmann]

On Mon, Oct 28, 2019 at 11:20:49AM +0100, Ilya Leoshkevich wrote:
> When cross-compiling tests from x86 to s390, the resulting BPF objects
> fail to load due to endianness mismatch.
> 
> Fix by using BPF-GCC endianness check for clang as well.
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> Acked-by: Andrii Nakryiko <andriin@fb.com>

Applied, thanks!