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selftests/bpf: Support cross-endian building
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Update Makefile build rules to compile BPF programs with target endianness
rather than host byte-order. With recent changes, this allows building the
full selftests/bpf suite hosted on x86_64 and targeting s390x or mips64eb
for example.

Signed-off-by: Tony Ambardar <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/bpf/880ccc6342cfc4d3c48b44f581e87adfbce2876e.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov <[email protected]>
guidosarducci authored and Alexei Starovoitov committed Oct 4, 2024

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1 parent 8ca3323 commit 5a63c33
Showing 1 changed file with 4 additions and 3 deletions.
7 changes: 4 additions & 3 deletions tools/testing/selftests/bpf/Makefile
Original file line number Diff line number Diff line change
@@ -445,6 +445,7 @@ endef
IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - </dev/null | \
grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__')
MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
BPF_TARGET_ENDIAN=$(if $(IS_LITTLE_ENDIAN),--target=bpfel,--target=bpfeb)

ifneq ($(CROSS_COMPILE),)
CLANG_TARGET_ARCH = --target=$(notdir $(CROSS_COMPILE:%-=%))
@@ -472,17 +473,17 @@ $(OUTPUT)/cgroup_getset_retval_hooks.o: cgroup_getset_retval_hooks.h
# $4 - binary name
define CLANG_BPF_BUILD_RULE
$(call msg,CLNG-BPF,$4,$2)
$(Q)$(CLANG) $3 -O2 --target=bpf -c $1 -mcpu=v3 -o $2
$(Q)$(CLANG) $3 -O2 $(BPF_TARGET_ENDIAN) -c $1 -mcpu=v3 -o $2
endef
# Similar to CLANG_BPF_BUILD_RULE, but with disabled alu32
define CLANG_NOALU32_BPF_BUILD_RULE
$(call msg,CLNG-BPF,$4,$2)
$(Q)$(CLANG) $3 -O2 --target=bpf -c $1 -mcpu=v2 -o $2
$(Q)$(CLANG) $3 -O2 $(BPF_TARGET_ENDIAN) -c $1 -mcpu=v2 -o $2
endef
# Similar to CLANG_BPF_BUILD_RULE, but with cpu-v4
define CLANG_CPUV4_BPF_BUILD_RULE
$(call msg,CLNG-BPF,$4,$2)
$(Q)$(CLANG) $3 -O2 --target=bpf -c $1 -mcpu=v4 -o $2
$(Q)$(CLANG) $3 -O2 $(BPF_TARGET_ENDIAN) -c $1 -mcpu=v4 -o $2
endef
# Build BPF object using GCC
define GCC_BPF_BUILD_RULE

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