From d966c3cab924fb750fefef11e77a6fa07dd5420e Mon Sep 17 00:00:00 2001 From: Andrea Righi <andrea.righi@canonical.com> Date: Fri, 10 Feb 2023 22:51:41 +0100 Subject: [PATCH] rust: allow to use INIT_STACK_ALL_ZERO With CONFIG_INIT_STACK_ALL_ZERO enabled, bindgen passes -ftrivial-auto-var-init=zero to clang, that triggers the following error: error: '-ftrivial-auto-var-init=zero' hasn't been enabled; enable it at your own peril for benchmarking purpose only with '-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang' However, this additional option that is currently required by clang is deprecated since clang-16 and going to be removed in the future, likely with clang-18. So, make sure bindgen is using this extra option if the major version of the libclang used by bindgen is < 16. In this way we can enable CONFIG_INIT_STACK_ALL_ZERO with CONFIG_RUST without triggering any build error. Link: https://github.com/llvm/llvm-project/issues/44842 Link: https://github.com/llvm/llvm-project/blob/llvmorg-16.0.0-rc2/clang/docs/ReleaseNotes.rst#deprecated-compiler-flags Signed-off-by: Andrea Righi <andrea.righi@canonical.com> Reviewed-by: Kees Cook <keescook@chromium.org> [Changed to < 16, added link and reworded] Signed-off-by: Miguel Ojeda <ojeda@kernel.org> --- rust/Makefile | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/rust/Makefile b/rust/Makefile index 41ac8401a8bef..aef85e9e8eeb8 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -262,6 +262,20 @@ BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH)) # some configurations, with new GCC versions, etc. bindgen_extra_c_flags = -w --target=$(BINDGEN_TARGET) +# Auto variable zero-initialization requires an additional special option with +# clang that is going to be removed sometime in the future (likely in +# clang-18), so make sure to pass this option only if clang supports it +# (libclang major version < 16). +# +# https://github.com/llvm/llvm-project/issues/44842 +# https://github.com/llvm/llvm-project/blob/llvmorg-16.0.0-rc2/clang/docs/ReleaseNotes.rst#deprecated-compiler-flags +ifdef CONFIG_INIT_STACK_ALL_ZERO +libclang_maj_ver=$(shell $(BINDGEN) $(srctree)/scripts/rust_is_available_bindgen_libclang.h 2>&1 | sed -ne 's/.*clang version \([0-9]*\).*/\1/p') +ifeq ($(shell expr $(libclang_maj_ver) \< 16), 1) +bindgen_extra_c_flags += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +endif +endif + bindgen_c_flags = $(filter-out $(bindgen_skip_c_flags), $(c_flags)) \ $(bindgen_extra_c_flags) endif -- GitLab