[PATCH V2] tools/virtio: fix build break for aarch64

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

"-mfunction-return=thunk -mindirect-branch-register" are only valid
for x86. So introduce compiler operation check to avoid such issues

Fixes: 0d0ed4006127 ("tools/virtio: enable to build with retpoline")
Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---

V2:
 Use /dev/null as output dest
 Move call cc-option to the original CFLAGS

 tools/virtio/Makefile | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/virtio/Makefile b/tools/virtio/Makefile
index 7b7139d97d74..d128925980e0 100644
--- a/tools/virtio/Makefile
+++ b/tools/virtio/Makefile
@@ -4,7 +4,18 @@ test: virtio_test vringh_test
 virtio_test: virtio_ring.o virtio_test.o
 vringh_test: vringh_test.o vringh.o virtio_ring.o
 
-CFLAGS += -g -O2 -Werror -Wno-maybe-uninitialized -Wall -I. -I../include/ -I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow -fno-strict-aliasing -fno-common -MMD -U_FORTIFY_SOURCE -include ../../include/linux/kconfig.h -mfunction-return=thunk -fcf-protection=none -mindirect-branch-register
+try-run = $(shell set -e;		\
+	if ($(1)) >/dev/null 2>&1;	\
+	then echo "$(2)";		\
+	else echo "$(3)";		\
+	fi)
+
+__cc-option = $(call try-run,\
+	$(1) -Werror $(2) -c -x c /dev/null -o /dev/null,$(2),)
+cc-option = $(call __cc-option, $(CC),$(1))
+
+CFLAGS += -g -O2 -Werror -Wno-maybe-uninitialized -Wall -I. -I../include/ -I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow -fno-strict-aliasing -fno-common -MMD -U_FORTIFY_SOURCE -include ../../include/linux/kconfig.h $(call cc-option,-mfunction-return=thunk) $(call cc-option,-fcf-protection=none) $(call cc-option,-mindirect-branch-register)
+
 CFLAGS += -pthread
 LDFLAGS += -pthread
 vpath %.c ../../drivers/virtio ../../drivers/vhost
-- 
2.37.1