powerpc/vdso: Filter clang's auto var init zero enabler when linking

After commit 8d9acfce3332 ("kbuild: Stop using '-Qunused-arguments' with
clang"), the PowerPC vDSO shows the following error with clang-13 and
older when CONFIG_INIT_STACK_ALL_ZERO is enabled:

  clang: error: argument unused during compilation: '-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang' [-Werror,-Wunused-command-line-argument]

clang-14 added a change to make sure this flag never triggers
-Wunused-command-line-argument, so it is fixed with newer releases. For
older releases that the kernel still supports building with, just filter
out this flag, as has been done for other flags.

Fixes: f0a42fbab447 ("powerpc/vdso: Improve linker flags")
Fixes: 8d9acfce3332 ("kbuild: Stop using '-Qunused-arguments' with clang")
Link: https://github.com/llvm/llvm-project/commit/ca6d5813d17598cd180995fb3bdfca00f364475f
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/Makefile b/Makefile
index 3e7f96f12f08959c93f7d16842f6a5cc82849a12..5bd587bb30b5778e137d99c804cd528ab4fe522a 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -912,7 +912,9 @@ ifdef CONFIG_INIT_STACK_ALL_ZERO
 KBUILD_CFLAGS  += -ftrivial-auto-var-init=zero
 ifdef CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO_ENABLER
 # https://github.com/llvm/llvm-project/issues/44842
-KBUILD_CFLAGS  += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
+CC_AUTO_VAR_INIT_ZERO_ENABLER := -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
+export CC_AUTO_VAR_INIT_ZERO_ENABLER
+KBUILD_CFLAGS  += $(CC_AUTO_VAR_INIT_ZERO_ENABLER)
 endif
 endif
 

diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 7e69e87fbf7440f26ed5e9c9d6ddd3af835969d9..d2a1dc0956d5169b35aadd0353bfde0458517db6 100644 (file)
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -56,7 +56,7 @@ ccflags-y := -fno-common -fno-builtin
 ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack
 ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
 # Filter flags that clang will warn are unused for linking
-ldflags-y += $(filter-out $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
+ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
 
 CC32FLAGS := -m32
 LD32FLAGS := -Wl,-soname=linux-vdso32.so.1