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>

1 files changed, 3 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 3e7f96f12f08..5bd587bb30b5 100644
--- 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