[PATCH v6 1/9] Makefile: Prepare for using macros for inline asm

[PATCH v6 1/9] Makefile: Prepare for using macros for inline asm

[Nadav Amit]

Using macros for inline assembly improves both readability and
compilation decisions that are distorted by big assembly blocks that use
alternative sections. Compile macros.S and use it to assemble all C
files. Currently, only x86 will use it.

Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-kbuild@vger.kernel.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 Makefile                 |  9 +++++++--
 arch/x86/Makefile        | 11 +++++++++--
 arch/x86/kernel/macros.S |  7 +++++++
 scripts/Kbuild.include   |  4 +++-
 scripts/mod/Makefile     |  2 ++
 5 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 arch/x86/kernel/macros.S

diff --git a/Makefile b/Makefile
index ca2af1ab91eb..66c1da72c156 100644
--- a/Makefile
+++ b/Makefile
@@ -1056,7 +1056,7 @@ scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
 # version.h and scripts_basic is processed / created.
 
 # Listed in dependency order
-PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3
+PHONY += prepare archprepare macroprepare prepare0 prepare1 prepare2 prepare3
 
 # prepare3 is used to check if we are building in a separate output directory,
 # and if so do:
@@ -1080,7 +1080,9 @@ prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
                    include/config/auto.conf
 	$(cmd_crmodverdir)
 
-archprepare: archheaders archscripts prepare1 scripts_basic
+macroprepare: prepare1 archmacros
+
+archprepare: archheaders archscripts macroprepare scripts_basic
 
 prepare0: archprepare gcc-plugins
 	$(Q)$(MAKE) $(build)=.
@@ -1148,6 +1150,9 @@ archheaders:
 PHONY += archscripts
 archscripts:
 
+PHONY += archmacros
+archmacros:
+
 PHONY += __headers
 __headers: $(version_h) scripts_basic uapi-asm-generic archheaders archscripts
 	$(Q)$(MAKE) $(build)=scripts build_unifdef
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f0a6ea22429d..363c3d8ed964 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -235,8 +235,8 @@ ifdef CONFIG_X86_64
 LDFLAGS += $(call ld-option, -z max-page-size=0x200000)
 endif
 
-# Speed up the build
-KBUILD_CFLAGS += -pipe
+# We cannot use -pipe flag since we give an additional .s file to the compiler
+#KBUILD_CFLAGS += -pipe
 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
 KBUILD_CFLAGS += -Wno-sign-compare
 #
@@ -258,11 +258,18 @@ archscripts: scripts_basic
 archheaders:
 	$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
 
+archmacros:
+	$(Q)$(MAKE) $(build)=arch/x86/kernel arch/x86/kernel/macros.s
+
 archprepare:
 ifeq ($(CONFIG_KEXEC_FILE),y)
 	$(Q)$(MAKE) $(build)=arch/x86/purgatory arch/x86/purgatory/kexec-purgatory.c
 endif
 
+ASM_MACRO_FLAGS = -Wa,arch/x86/kernel/macros.s
+export ASM_MACRO_FLAGS
+KBUILD_CFLAGS += $(ASM_MACRO_FLAGS)
+
 ###
 # Kernel objects
 
diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S
new file mode 100644
index 000000000000..cfc1c7d1a6eb
--- /dev/null
+++ b/arch/x86/kernel/macros.S
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * This file includes headers whose assembly part includes macros which are
+ * commonly used. The macros are precompiled into assmebly file which is later
+ * assembled together with each compiled file.
+ */
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index c8156d61678c..8eeb5636a2a7 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -115,7 +115,9 @@ __cc-option = $(call try-run,\
 
 # 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))
+# In addition, do not include the asm macros which are built later.
+CC_OPTION_FILTERED = $(GCC_PLUGINS_CFLAGS) $(ASM_MACRO_FLAGS)
+CC_OPTION_CFLAGS = $(filter-out $(CC_OPTION_FILTERED),$(KBUILD_CFLAGS))
 
 # cc-option
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
index 42c5d50f2bcc..a5b4af47987a 100644
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -4,6 +4,8 @@ OBJECT_FILES_NON_STANDARD := y
 hostprogs-y	:= modpost mk_elfconfig
 always		:= $(hostprogs-y) empty.o
 
+CFLAGS_REMOVE_empty.o := $(ASM_MACRO_FLAGS)
+
 modpost-objs	:= modpost.o file2alias.o sumversion.o
 
 devicetable-offsets-file := devicetable-offsets.h
-- 
2.17.1

Re: [PATCH v6 1/9] Makefile: Prepare for using macros for inline asm

[Masahiro Yamada]

2018-06-23 2:22 GMT+09:00 Nadav Amit <namit@vmware.com>:
> Using macros for inline assembly improves both readability and
> compilation decisions that are distorted by big assembly blocks that use
> alternative sections. Compile macros.S and use it to assemble all C
> files. Currently, only x86 will use it.
>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: Michal Marek <michal.lkml@markovi.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Cc: linux-kbuild@vger.kernel.org
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Signed-off-by: Nadav Amit <namit@vmware.com>
> ---



Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>




>  Makefile                 |  9 +++++++--
>  arch/x86/Makefile        | 11 +++++++++--
>  arch/x86/kernel/macros.S |  7 +++++++
>  scripts/Kbuild.include   |  4 +++-
>  scripts/mod/Makefile     |  2 ++
>  5 files changed, 28 insertions(+), 5 deletions(-)
>  create mode 100644 arch/x86/kernel/macros.S
>
> diff --git a/Makefile b/Makefile
> index ca2af1ab91eb..66c1da72c156 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1056,7 +1056,7 @@ scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
>  # version.h and scripts_basic is processed / created.
>
>  # Listed in dependency order
> -PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3
> +PHONY += prepare archprepare macroprepare prepare0 prepare1 prepare2 prepare3
>
>  # prepare3 is used to check if we are building in a separate output directory,
>  # and if so do:
> @@ -1080,7 +1080,9 @@ prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
>                     include/config/auto.conf
>         $(cmd_crmodverdir)
>
> -archprepare: archheaders archscripts prepare1 scripts_basic
> +macroprepare: prepare1 archmacros
> +
> +archprepare: archheaders archscripts macroprepare scripts_basic
>
>  prepare0: archprepare gcc-plugins
>         $(Q)$(MAKE) $(build)=.
> @@ -1148,6 +1150,9 @@ archheaders:
>  PHONY += archscripts
>  archscripts:
>
> +PHONY += archmacros
> +archmacros:
> +
>  PHONY += __headers
>  __headers: $(version_h) scripts_basic uapi-asm-generic archheaders archscripts
>         $(Q)$(MAKE) $(build)=scripts build_unifdef
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index f0a6ea22429d..363c3d8ed964 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -235,8 +235,8 @@ ifdef CONFIG_X86_64
>  LDFLAGS += $(call ld-option, -z max-page-size=0x200000)
>  endif
>
> -# Speed up the build
> -KBUILD_CFLAGS += -pipe
> +# We cannot use -pipe flag since we give an additional .s file to the compiler
> +#KBUILD_CFLAGS += -pipe
>  # Workaround for a gcc prelease that unfortunately was shipped in a suse release
>  KBUILD_CFLAGS += -Wno-sign-compare
>  #
> @@ -258,11 +258,18 @@ archscripts: scripts_basic
>  archheaders:
>         $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
>
> +archmacros:
> +       $(Q)$(MAKE) $(build)=arch/x86/kernel arch/x86/kernel/macros.s
> +
>  archprepare:
>  ifeq ($(CONFIG_KEXEC_FILE),y)
>         $(Q)$(MAKE) $(build)=arch/x86/purgatory arch/x86/purgatory/kexec-purgatory.c
>  endif
>
> +ASM_MACRO_FLAGS = -Wa,arch/x86/kernel/macros.s
> +export ASM_MACRO_FLAGS
> +KBUILD_CFLAGS += $(ASM_MACRO_FLAGS)
> +
>  ###
>  # Kernel objects
>
> diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S
> new file mode 100644
> index 000000000000..cfc1c7d1a6eb
> --- /dev/null
> +++ b/arch/x86/kernel/macros.S
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +/*
> + * This file includes headers whose assembly part includes macros which are
> + * commonly used. The macros are precompiled into assmebly file which is later
> + * assembled together with each compiled file.
> + */
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index c8156d61678c..8eeb5636a2a7 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -115,7 +115,9 @@ __cc-option = $(call try-run,\
>
>  # 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))
> +# In addition, do not include the asm macros which are built later.
> +CC_OPTION_FILTERED = $(GCC_PLUGINS_CFLAGS) $(ASM_MACRO_FLAGS)
> +CC_OPTION_CFLAGS = $(filter-out $(CC_OPTION_FILTERED),$(KBUILD_CFLAGS))
>
>  # cc-option
>  # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
> diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
> index 42c5d50f2bcc..a5b4af47987a 100644
> --- a/scripts/mod/Makefile
> +++ b/scripts/mod/Makefile
> @@ -4,6 +4,8 @@ OBJECT_FILES_NON_STANDARD := y
>  hostprogs-y    := modpost mk_elfconfig
>  always         := $(hostprogs-y) empty.o
>
> +CFLAGS_REMOVE_empty.o := $(ASM_MACRO_FLAGS)
> +
>  modpost-objs   := modpost.o file2alias.o sumversion.o
>
>  devicetable-offsets-file := devicetable-offsets.h
> --
> 2.17.1
>
> --
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-- 
Best Regards
Masahiro Yamada

Re: [PATCH v6 1/9] Makefile: Prepare for using macros for inline asm

[Ingo Molnar]

* Masahiro Yamada <yamada.masahiro@socionext.com> wrote:

> 2018-06-23 2:22 GMT+09:00 Nadav Amit <namit@vmware.com>:
> > Using macros for inline assembly improves both readability and
> > compilation decisions that are distorted by big assembly blocks that use
> > alternative sections. Compile macros.S and use it to assemble all C
> > files. Currently, only x86 will use it.
> >
> > Cc: Sam Ravnborg <sam@ravnborg.org>
> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> > Cc: Michal Marek <michal.lkml@markovi.net>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > Cc: x86@kernel.org
> > Cc: linux-kbuild@vger.kernel.org
> > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Signed-off-by: Nadav Amit <namit@vmware.com>
> > ---
> 
> 
> 
> Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> 
> 
> 
> 
> >  Makefile                 |  9 +++++++--
> >  arch/x86/Makefile        | 11 +++++++++--
> >  arch/x86/kernel/macros.S |  7 +++++++
> >  scripts/Kbuild.include   |  4 +++-
> >  scripts/mod/Makefile     |  2 ++
> >  5 files changed, 28 insertions(+), 5 deletions(-)
> >  create mode 100644 arch/x86/kernel/macros.S

So this patch appears to break the xtensa cross-build on my system, with an older 
version of crosstools:

  MODPOST vmlinux.o
/home/mingo/crosstool-korg/bin//gcc-4.9.0-nolibc/xtensa-linux/bin/xtensa-linux-ld:./arch/xtensa/kernel/vmlinux.lds:430: 
syntax error
/home/mingo/tip/Makefile:1010: recipe for target 'vmlinux' failed
make[1]: *** [vmlinux] Error 1
make[1]: Leaving directory '/dev/shm/tip/build'
Makefile:146: recipe for target 'sub-make' failed

Thanks,

	Ingo

Re: [PATCH v6 1/9] Makefile: Prepare for using macros for inline asm

[Nadav Amit]

at 4:14 AM, Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
> 
>> 2018-06-23 2:22 GMT+09:00 Nadav Amit <namit@vmware.com>:
>>> Using macros for inline assembly improves both readability and
>>> compilation decisions that are distorted by big assembly blocks that use
>>> alternative sections. Compile macros.S and use it to assemble all C
>>> files. Currently, only x86 will use it.
>>> 
>>> Cc: Sam Ravnborg <sam@ravnborg.org>
>>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>>> Cc: Michal Marek <michal.lkml@markovi.net>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: Ingo Molnar <mingo@redhat.com>
>>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>>> Cc: x86@kernel.org
>>> Cc: linux-kbuild@vger.kernel.org
>>> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>>> Signed-off-by: Nadav Amit <namit@vmware.com>
>>> ---
>> 
>> 
>> 
>> Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> 
>> 
>> 
>> 
>>> Makefile                 |  9 +++++++--
>>> arch/x86/Makefile        | 11 +++++++++--
>>> arch/x86/kernel/macros.S |  7 +++++++
>>> scripts/Kbuild.include   |  4 +++-
>>> scripts/mod/Makefile     |  2 ++
>>> 5 files changed, 28 insertions(+), 5 deletions(-)
>>> create mode 100644 arch/x86/kernel/macros.S
> 
> So this patch appears to break the xtensa cross-build on my system, with an older 
> version of crosstools:
> 
>  MODPOST vmlinux.o
> /home/mingo/crosstool-korg/bin//gcc-4.9.0-nolibc/xtensa-linux/bin/xtensa-linux-ld:./arch/xtensa/kernel/vmlinux.lds:430: 
> syntax error
> /home/mingo/tip/Makefile:1010: recipe for target 'vmlinux' failed
> make[1]: *** [vmlinux] Error 1
> make[1]: Leaving directory '/dev/shm/tip/build'
> Makefile:146: recipe for target 'sub-make’ failed

This one is due to a missing -DLINKER_SCRIPT in the Makefile of xtensa. I’ll
send the patch to fix it after I deal with the boot failure (for which I
wait for your config file).

Thanks,
Nadav