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

After commit 8d9acfce33 ("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: f0a42fbab4 ("powerpc/vdso: Improve linker flags")
Fixes: 8d9acfce33 ("kbuild: Stop using '-Qunused-arguments' with clang")
Link: ca6d5813d1
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Nathan Chancellor 2023-01-24 09:19:28 -07:00 committed by Masahiro Yamada
parent 58e0e5c85e
commit 4e3feaad6f
2 changed files with 4 additions and 2 deletions
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4
Makefile
View File

@ -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

2
arch/powerpc/kernel/vdso/Makefile
View File

@ -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