Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 33/59] x86/build: Use cc-option to validate stack alignment parameter | Date | Wed, 21 Nov 2018 20:06:48 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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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: Nick Desaulniers <ndesaulniers@google.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)
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