4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthias Kaehlcke mka@chromium.org
commit 9e8730b178a2472fca3123e909d6e69cc8127778 upstream.
With the following commit:
8f91869766c0 ("x86/build: Fix stack alignment for CLang")
cc-option is only used to determine the name of the stack alignment option supported by the compiler, but not to verify that the actual parameter <option>=N is valid in combination with the other CFLAGS.
This causes problems (as reported by the kbuild robot) with older GCC versions which only support stack alignment on a boundary of 16 bytes or higher.
Also use (__)cc_option to add the stack alignment option to CFLAGS to make sure only valid options are added.
Reported-by: kbuild test robot fengguang.wu@intel.com Signed-off-by: Matthias Kaehlcke mka@chromium.org Cc: Arnd Bergmann arnd@arndb.de Cc: Bernhard.Rosenkranzer@linaro.org Cc: Greg Hackmann ghackmann@google.com Cc: Kees Cook keescook@chromium.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Masahiro Yamada yamada.masahiro@socionext.com Cc: Michael Davidson md@google.com Cc: Nick Desaulniers ndesaulniers@google.com Cc: Peter Zijlstra peterz@infradead.org Cc: Stephen Hines srhines@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: dianders@chromium.org Fixes: 8f91869766c0 ("x86/build: Fix stack alignment for CLang") Link: http://lkml.kernel.org/r/20170817182047.176752-1-mka@chromium.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/Makefile | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -38,7 +38,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os
REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector) -REALMODE_CFLAGS += $(cc_stack_align4) +REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4)) export REALMODE_CFLAGS
# BITS is used as extension for files which are available in a 32 bit @@ -78,7 +78,7 @@ ifeq ($(CONFIG_X86_32),y) # Align the stack to the register width instead of using the default # alignment of 16 bytes. This reduces stack usage and the number of # alignment instructions. - KBUILD_CFLAGS += $(cc_stack_align4) + KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use # a lot more stack due to the lack of sharing of stacklots: @@ -117,7 +117,7 @@ else # default alignment which keep the stack *mis*aligned. # Furthermore an alignment to the register width reduces stack usage # and the number of alignment instructions. - KBUILD_CFLAGS += $(cc_stack_align8) + KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
# Use -mskip-rax-setup if supported. KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)