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From: Nadav Amit <namit@vmware.com>
To: Ingo Molnar <mingo@redhat.com>
Cc: <x86@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	<linux-kernel@vger.kernel.org>, Nadav Amit <namit@vmware.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Michal Marek <michal.lkml@markovi.net>,
	"H. Peter Anvin" <hpa@zytor.com>, <linux-kbuild@vger.kernel.org>
Subject: [PATCH v7 02/10] Makefile: Prepare for using macros for inline asm
Date: Thu, 9 Aug 2018 13:15:45 -0700
Message-ID: <20180809201554.168804-3-namit@vmware.com> (raw)
In-Reply-To: <20180809201554.168804-1-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>
---
 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 7a3c4548162b..39d790e74e0d 100644
--- a/Makefile
+++ b/Makefile
@@ -1051,7 +1051,7 @@ 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:
@@ -1075,7 +1075,9 @@ 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)=.
@@ -1143,6 +1145,9 @@ 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 a08e82856563..a4b90ac1629b 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
 #
@@ -258,6 +258,13 @@ archscripts: scripts_basic
 archheaders:
 	$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
 
+archmacros:
+	$(Q)$(MAKE) $(build)=arch/x86/kernel arch/x86/kernel/macros.s
+
+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 86321f06461e..d7b7aadb6cd8 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


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-09 20:15 [PATCH v7 00/10] x86: macrofying inline asm for better compilation Nadav Amit
2018-08-09 20:15 ` [PATCH v7 01/10] xtensa: defining LINKER_SCRIPT for the linker script Nadav Amit
2018-08-09 20:25   ` Max Filippov
2018-08-09 20:15 ` Nadav Amit [this message]
2018-08-10  1:39   ` [PATCH v7 02/10] Makefile: Prepare for using macros for inline asm Masahiro Yamada
2018-08-09 20:15 ` [PATCH v7 03/10] x86: objtool: use asm macro for better compiler decisions Nadav Amit
2018-08-09 20:15 ` [PATCH v7 04/10] x86: refcount: prevent gcc distortions Nadav Amit
2018-08-09 20:15 ` [PATCH v7 05/10] x86: alternatives: macrofy locks for better inlining Nadav Amit
2018-08-09 20:15 ` [PATCH v7 06/10] x86: bug: prevent gcc distortions Nadav Amit
2018-08-09 20:15 ` [PATCH v7 07/10] x86: prevent inline distortion by paravirt ops Nadav Amit
2018-08-09 20:15 ` [PATCH v7 08/10] x86: extable: use macros instead of inline assembly Nadav Amit
2018-08-09 20:15 ` [PATCH v7 09/10] x86: cpufeature: " Nadav Amit
2018-08-09 20:15 ` [PATCH v7 10/10] x86: jump-labels: " Nadav Amit
2018-09-04 17:14 ` [PATCH v7 00/10] x86: macrofying inline asm for better compilation Nadav Amit
2018-09-10 13:00   ` Ingo Molnar
2018-09-10 17:00     ` Nadav Amit

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