On Wed, Mar 22, 2023 at 03:59:45PM +0800, Peng Fan (OSS) wrote:
> 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>
> ---
> tools/virtio/Makefile | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/tools/virtio/Makefile b/tools/virtio/Makefile
> index 7b7139d97d74..1a9e1be52e4f 100644
> --- a/tools/virtio/Makefile
> +++ b/tools/virtio/Makefile
> @@ -4,7 +4,26 @@ 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
> +TMPOUT = .tmp_$$$$
if you are going to do this pls use mktemp.
But I don't see why not just use -o /dev/null
> +try-run = $(shell set -e; \
> + TMP=$(TMPOUT)/tmp; \
> + trap "rm -rf $(TMPOUT)" EXIT; \
> + mkdir -p $(TMPOUT); \
> + if ($(1)) >/dev/null 2>&1; \
> + then echo "$(2)"; \
> + else echo "$(3)"; \
> + fi)
> +
> +__cc-option = $(call try-run,\
> + $(1) -Werror $(2) -c -x c /dev/null -o "$$TMP",$(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
> +
> +CFLAGS += $(call cc-option,-mfunction-return=thunk)
> +CFLAGS += $(call cc-option,-fcf-protection=none)
> +CFLAGS += $(call cc-option,-mindirect-branch-register)
> +
As far as I can tell this will do the dance with the empty input
each time CFLAGS is evaluated.
Which seems unnecessarily baroque - just use ":=" and it will
be evaluated once.
> CFLAGS += -pthread
> LDFLAGS += -pthread
> vpath %.c ../../drivers/virtio ../../drivers/vhost
> --
> 2.37.1
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