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[PATCH v5 0/3] x86: stack alignment for boot code and clang

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  [PATCH v5 0/3] x86: stack alignment for boot code and clang Matthias Kaehlcke <mka@chromium.org> - 2017-06-22 01:30 +0200
    [PATCH v5 1/3] kbuild: Add __cc-option macro Matthias Kaehlcke <mka@chromium.org> - 2017-06-22 01:30 +0200
    Re: [PATCH v5 0/3] x86: stack alignment for boot code and clang Ingo Molnar <mingo@kernel.org> - 2017-06-22 11:00 +0200
      Re: [PATCH v5 0/3] x86: stack alignment for boot code and clang Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-25 06:10 +0200

#1672145 — [PATCH v5 0/3] x86: stack alignment for boot code and clang

This series fixes an issue with the stack of the x86 boot code not
being aligned as intended. Further it adapts the Makefile to account
for the fact that clang uses a different option to configure the
stack alignment than gcc (-mstack-alignment=N vs
-mpreferred-stack-boundary=N)

Collaterally the series adds the new kbuild macro __cc-option and
refactors the macros cc-option and hostcc-option to make use of
__cc-option.

Matthias Kaehlcke (3):
  kbuild: Add __cc-option macro
  x86/build: Use __cc-option for boot code compiler options
  x86/build: Specify stack alignment for clang

 Makefile               |  2 +-
 arch/x86/Makefile      | 33 +++++++++++++++++++++++++--------
 scripts/Kbuild.include | 14 ++++++++++++--
 scripts/Makefile.host  |  6 ------
 4 files changed, 38 insertions(+), 17 deletions(-)

-- 
2.13.1.611.g7e3b11ae1-goog

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#1672150 — [PATCH v5 1/3] kbuild: Add __cc-option macro

cc-option uses KBUILD_CFLAGS and KBUILD_CPPFLAGS when it determines
whether an option is supported or not. This is fine for options used to
build the kernel itself, however some components like the x86 boot code
use a different set of flags.

Add the new macro __cc-option which is a more generic version of
cc-option with additional parameters. One parameter is the compiler
with which the check should be performed, the other the compiler options
to be used instead KBUILD_C*FLAGS.

Refactor cc-option and hostcc-option to use __cc-option and move
hostcc-option to scripts/Kbuild.include.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
Changes in v5:
- removed extra whitespace in value returned by cc-option

 Makefile               |  2 +-
 scripts/Kbuild.include | 14 ++++++++++++--
 scripts/Makefile.host  |  6 ------
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index 83f6d9972cab..b234bba6d652 100644
--- a/Makefile
+++ b/Makefile
@@ -303,7 +303,7 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 
 HOSTCC       = gcc
 HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
+HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
 HOSTCXXFLAGS = -O2
 
 ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 61f87a99bf0a..b2cfa444f855 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -108,6 +108,11 @@ as-option = $(call try-run,\
 as-instr = $(call try-run,\
 	printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
 
+# __cc-option
+# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586)
+__cc-option = $(call try-run,\
+	$(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4))
+
 # Do not attempt to build with gcc plugins during cc-option tests.
 # (And this uses delayed resolution so the flags will be up to date.)
 CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
@@ -115,8 +120,13 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 # cc-option
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
-cc-option = $(call try-run,\
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
+cc-option = $(call __cc-option, $(CC),\
+	$(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
+
+# hostcc-option
+# Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)
+hostcc-option = $(call __cc-option, $(HOSTCC),\
+	$(HOSTCFLAGS) $(HOST_EXTRACFLAGS),$(1),$(2))
 
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 45b5b1aaedbd..9cfd5c84d76f 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -20,12 +20,6 @@
 # Will compile qconf as a C++ program, and menu as a C program.
 # They are linked as C++ code to the executable qconf
 
-# hostcc-option
-# Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)
-
-hostcc-option = $(call try-run,\
-	$(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
-
 __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
 host-cshlib := $(sort $(hostlibs-y) $(hostlibs-m))
 host-cxxshlib := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
-- 
2.13.1.611.g7e3b11ae1-goog

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#1672434

* Matthias Kaehlcke <mka@chromium.org> wrote:

> This series fixes an issue with the stack of the x86 boot code not
> being aligned as intended. Further it adapts the Makefile to account
> for the fact that clang uses a different option to configure the
> stack alignment than gcc (-mstack-alignment=N vs
> -mpreferred-stack-boundary=N)
> 
> Collaterally the series adds the new kbuild macro __cc-option and
> refactors the macros cc-option and hostcc-option to make use of
> __cc-option.
> 
> Matthias Kaehlcke (3):
>   kbuild: Add __cc-option macro
>   x86/build: Use __cc-option for boot code compiler options
>   x86/build: Specify stack alignment for clang
> 
>  Makefile               |  2 +-
>  arch/x86/Makefile      | 33 +++++++++++++++++++++++++--------
>  scripts/Kbuild.include | 14 ++++++++++++--
>  scripts/Makefile.host  |  6 ------
>  4 files changed, 38 insertions(+), 17 deletions(-)

So given that there are non-trivial kbuild changes here, I'd suggest these patches 
might have a better home in the kbuild tree. For the x86 bits:

Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo

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#1674173

2017-06-22 17:58 GMT+09:00 Ingo Molnar <mingo@kernel.org>:
>
> * Matthias Kaehlcke <mka@chromium.org> wrote:
>
>> This series fixes an issue with the stack of the x86 boot code not
>> being aligned as intended. Further it adapts the Makefile to account
>> for the fact that clang uses a different option to configure the
>> stack alignment than gcc (-mstack-alignment=N vs
>> -mpreferred-stack-boundary=N)
>>
>> Collaterally the series adds the new kbuild macro __cc-option and
>> refactors the macros cc-option and hostcc-option to make use of
>> __cc-option.
>>
>> Matthias Kaehlcke (3):
>>   kbuild: Add __cc-option macro
>>   x86/build: Use __cc-option for boot code compiler options
>>   x86/build: Specify stack alignment for clang
>>
>>  Makefile               |  2 +-
>>  arch/x86/Makefile      | 33 +++++++++++++++++++++++++--------
>>  scripts/Kbuild.include | 14 ++++++++++++--
>>  scripts/Makefile.host  |  6 ------
>>  4 files changed, 38 insertions(+), 17 deletions(-)
>
> So given that there are non-trivial kbuild changes here, I'd suggest these patches
> might have a better home in the kbuild tree. For the x86 bits:
>
> Acked-by: Ingo Molnar <mingo@kernel.org>
>
> Thanks,
>
>         Ingo
> --
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Series applied to linux-kbuild/kbuild.




-- 
Best Regards
Masahiro Yamada

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