[PATCH 1/2] kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled

[PATCH 1/2] kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled

[Masahiro Yamada]

Currently, the top Makefile includes all of scripts/Makefile.<feature>
even if the associated CONFIG option is disabled.

Do not include unneeded Makefiles in order to slightly optimize the
parse stage.

Include $(include-y), and ignore $(include-).

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile               | 16 +++++++++-------
 scripts/Makefile.kcov  |  4 ----
 scripts/Makefile.kcsan |  4 ----
 scripts/Makefile.ubsan |  3 ---
 4 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/Makefile b/Makefile
index ebf4d3ce492c..483456d5dd3e 100644
--- a/Makefile
+++ b/Makefile
@@ -745,9 +745,6 @@ endif
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 KBUILD_CFLAGS	+= $(call cc-option,-fno-allow-store-data-races)
 
-include scripts/Makefile.kcov
-include scripts/Makefile.gcc-plugins
-
 ifdef CONFIG_READABLE_ASM
 # Disable optimizations that make assembler listings hard to read.
 # reorder blocks reorders the control in the function
@@ -948,10 +945,15 @@ ifdef CONFIG_RETPOLINE
 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
 endif
 
-include scripts/Makefile.kasan
-include scripts/Makefile.extrawarn
-include scripts/Makefile.ubsan
-include scripts/Makefile.kcsan
+# include additional Makefiles when needed
+include-y			:= scripts/Makefile.extrawarn
+include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
+include-$(CONFIG_KCSAN)		+= scripts/Makefile.kcsan
+include-$(CONFIG_UBSAN)		+= scripts/Makefile.ubsan
+include-$(CONFIG_KCOV)		+= scripts/Makefile.kcov
+include-$(CONFIG_GCC_PLUGINS)	+= scripts/Makefile.gcc-plugins
+
+include $(addprefix $(srctree)/, $(include-y))
 
 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 KBUILD_CPPFLAGS += $(KCPPFLAGS)
diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov
index 52b113302443..67e8cfe3474b 100644
--- a/scripts/Makefile.kcov
+++ b/scripts/Makefile.kcov
@@ -1,10 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
-ifdef CONFIG_KCOV
-
 kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC)	+= -fsanitize-coverage=trace-pc
 kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS)	+= -fsanitize-coverage=trace-cmp
 kcov-flags-$(CONFIG_GCC_PLUGIN_SANCOV)		+= -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so
 
 export CFLAGS_KCOV := $(kcov-flags-y)
-
-endif
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index bd4da1af5953..2b0743e6566e 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -1,6 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-ifdef CONFIG_KCSAN
-
 # GCC and Clang accept backend options differently. Do not wrap in cc-option,
 # because Clang accepts "--param" even if it is unused.
 ifdef CONFIG_CC_IS_CLANG
@@ -15,5 +13,3 @@ CFLAGS_KCSAN := -fsanitize=thread \
 	$(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
 	$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1)) \
 	$(call cc-param,tsan-distinguish-volatile=1)
-
-endif # CONFIG_KCSAN
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 5b15bc425ec9..27348029b2b8 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -1,6 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-ifdef CONFIG_UBSAN
-
 ifdef CONFIG_UBSAN_ALIGNMENT
       CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
 endif
@@ -26,4 +24,3 @@ endif
       # -fsanitize=* options makes GCC less smart than usual and
       # increase number of 'maybe-uninitialized false-positives
       CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
-endif
-- 
2.25.1

[PATCH 2/2] kbuild: stop filtering out $(GCC_PLUGINS_CFLAGS) from cc-option base

[Masahiro Yamada]

Commit d26e94149276 ("kbuild: no gcc-plugins during cc-option tests")
was neeeded because scripts/Makefile.gcc-plugins was too early.

This is unneeded by including scripts/Makefile.gcc-plugins last,
and being careful to not add cc-option tests after it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile               |  5 ++++-
 scripts/Kbuild.include | 10 +++-------
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/Makefile b/Makefile
index 483456d5dd3e..712206381a27 100644
--- a/Makefile
+++ b/Makefile
@@ -506,7 +506,6 @@ KBUILD_CFLAGS_MODULE  := -DMODULE
 KBUILD_LDFLAGS_MODULE :=
 export KBUILD_LDS_MODULE := $(srctree)/scripts/module-common.lds
 KBUILD_LDFLAGS :=
-GCC_PLUGINS_CFLAGS :=
 CLANG_FLAGS :=
 
 export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
@@ -955,6 +954,10 @@ include-$(CONFIG_GCC_PLUGINS)	+= scripts/Makefile.gcc-plugins
 
 include $(addprefix $(srctree)/, $(include-y))
 
+# scripts/Makefile.gcc-plugins is intentionally included last.
+# Do not add $(call cc-option,...) below this line. When you build the kernel
+# from the clean source tree, the GCC plugins do not exist at this point.
+
 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 KBUILD_CPPFLAGS += $(KCPPFLAGS)
 KBUILD_AFLAGS   += $(KAFLAGS)
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 9a15fbf66aa1..83a1637417e5 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -119,25 +119,21 @@ as-instr = $(call try-run,\
 __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))
-
 # cc-option
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
 cc-option = $(call __cc-option, $(CC),\
-	$(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
+	$(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS),$(1),$(2))
 
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
+	$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
 
 # cc-disable-warning
 # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
 cc-disable-warning = $(call try-run,\
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
+	$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
 # cc-ifversion
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
-- 
2.25.1