[PATCH v3 bpf-next 12/14] samples: bpf: makefile: provide C/CXX/LD flags to libbpf

[Ivan Khoronzhuk]

In order to build libs using C/CXX/LD flags of target arch,
provide them to libbpf make.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
---
 samples/bpf/Makefile | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 18ec22e7b444..133123d4c7d7 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -182,8 +182,6 @@ ifdef CROSS_COMPILE
 TPROGS_CFLAGS += -Wall
 TPROGS_CFLAGS += -O2
 TPROGS_CFLAGS += -fomit-frame-pointer
-TPROGS_CFLAGS += -Wmissing-prototypes
-TPROGS_CFLAGS += -Wstrict-prototypes
 else
 TPROGS_LDLIBS := $(KBUILD_HOSTLDLIBS)
 TPROGS_CFLAGS += $(KBUILD_HOSTCFLAGS) $(HOST_EXTRACFLAGS)
@@ -196,6 +194,14 @@ TPROGS_CFLAGS += -I$(srctree)/tools/lib/
 TPROGS_CFLAGS += -I$(srctree)/tools/include
 TPROGS_CFLAGS += -I$(srctree)/tools/perf
 
+EXTRA_CXXFLAGS := $(TPROGS_CFLAGS)
+
+# options not valid for C++
+ifdef CROSS_COMPILE
+$(TPROGS_CFLAGS) += -Wmissing-prototypes
+$(TPROGS_CFLAGS) += -Wstrict-prototypes
+endif
+
 TPROGCFLAGS_bpf_load.o += -Wno-unused-variable
 
 TPROGS_LDLIBS			+= $(LIBBPF) -lelf
@@ -257,7 +263,9 @@ clean:
 
 $(LIBBPF): FORCE
 # Fix up variables inherited from Kbuild that tools/ build system won't like
-	$(MAKE) -C $(dir $@) RM='rm -rf' LDFLAGS= srctree=$(BPF_SAMPLES_PATH)/../../ O=
+	$(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \
+		EXTRA_CXXFLAGS="$(EXTRA_CXXFLAGS)" LDFLAGS=$(TPROGS_LDFLAGS) \
+		srctree=$(BPF_SAMPLES_PATH)/../../ O=
 
 $(obj)/syscall_nrs.h:	$(obj)/syscall_nrs.s FORCE
 	$(call filechk,offsets,__SYSCALL_NRS_H__)
-- 
2.17.1