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| Started by | Matthias Kaehlcke <mka@chromium.org> |
|---|---|
| First post | 2017-08-17 20:30 +0200 |
| Last post | 2017-08-21 11:30 +0200 |
| Articles | 3 — 3 participants |
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[PATCH] x86/build: Use cc-option to validate stack alignment parameter Matthias Kaehlcke <mka@chromium.org> - 2017-08-17 20:30 +0200
Re: [PATCH] x86/build: Use cc-option to validate stack alignment parameter Ingo Molnar <mingo@kernel.org> - 2017-08-21 10:00 +0200
[tip:x86/build] x86/build: Use cc-option to validate stack alignment parameter tip-bot for Matthias Kaehlcke <tipbot@zytor.com> - 2017-08-21 11:30 +0200
| From | Matthias Kaehlcke <mka@chromium.org> |
|---|---|
| Date | 2017-08-17 20:30 +0200 |
| Subject | [PATCH] x86/build: Use cc-option to validate stack alignment parameter |
| Message-ID | <ufxIm-bd-15@gated-at.bofh.it> |
With 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 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.
Fixes: 8f91869766c0 ("x86/build: Fix stack alignment for CLang")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
arch/x86/Makefile | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 65ed359eb904..9231bbfae670 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -38,7 +38,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \
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)
--
2.14.1.480.gb18f417b89-goog
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| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2017-08-21 10:00 +0200 |
| Subject | Re: [PATCH] x86/build: Use cc-option to validate stack alignment parameter |
| Message-ID | <ugPMS-1su-17@gated-at.bofh.it> |
| In reply to | #1714282 |
* Matthias Kaehlcke <mka@chromium.org> wrote:
> With 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 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.
>
> Fixes: 8f91869766c0 ("x86/build: Fix stack alignment for CLang")
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
I've added the kbuild-bot Reported-by tag to document (and credit) how this bug
was found.
Thanks,
Ingo
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| From | tip-bot for Matthias Kaehlcke <tipbot@zytor.com> |
|---|---|
| Date | 2017-08-21 11:30 +0200 |
| Subject | [tip:x86/build] x86/build: Use cc-option to validate stack alignment parameter |
| Message-ID | <ugRbY-2zH-21@gated-at.bofh.it> |
| In reply to | #1714282 |
Commit-ID: 9e8730b178a2472fca3123e909d6e69cc8127778
Gitweb: http://git.kernel.org/tip/9e8730b178a2472fca3123e909d6e69cc8127778
Author: Matthias Kaehlcke <mka@chromium.org>
AuthorDate: Thu, 17 Aug 2017 11:20:47 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 21 Aug 2017 09:53:15 +0200
x86/build: Use cc-option to validate stack alignment parameter
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>
---
arch/x86/Makefile | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 48f3ae7..6276572 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -38,7 +38,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \
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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