From 5a63c33d6f00e1739944cea2f445819951610c7d Mon Sep 17 00:00:00 2001
From: Tony Ambardar <tony.ambardar@gmail.com>
Date: Mon, 16 Sep 2024 01:37:47 -0700
Subject: [PATCH] selftests/bpf: Support cross-endian building

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 <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/880ccc6342cfc4d3c48b44f581e87adfbce2876e.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/Makefile | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 365740f24d2e..e295e3df5ec6 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -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
-- 
2.50.1