Merge tag 'kbuild-v4.21' of git://git.kernel.org/pub/scm/linux/kernel…

…/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:
 "Kbuild core:
   - remove unneeded $(call cc-option,...) switches
   - consolidate Clang compiler flags into CLANG_FLAGS
   - announce the deprecation of SUBDIRS
   - fix single target build for external module
   - simplify the dependencies of 'prepare' stage targets
   - allow fixdep to directly write to .*.cmd files
   - simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS
   - change if_changed_rule to accept multi-line recipe
   - move .SECONDARY special target to scripts/Kbuild.include
   - remove redundant 'set -e'
   - improve parallel execution for CONFIG_HEADERS_CHECK
   - misc cleanups

  Treewide fixes and cleanups
   - set Clang flags correctly for PowerPC boot images
   - fix UML build error with CONFIG_GCC_PLUGINS
   - remove unneeded patterns from .gitignore files
   - refactor firmware/Makefile
   - remove unneeded rules for *offsets.s
   - avoid unneeded regeneration of intermediate .s files
   - clean up ./Kbuild

  Modpost:
   - remove unused -M, -K options
   - fix false positive warnings about section mismatch
   - use simple devtable lookup instead of linker magic
   - misc cleanups

  Coccinelle:
   - relax boolinit.cocci checks for overall consistency
   - fix warning messages of boolinit.cocci

  Other tools:
   - improve -dirty check of scripts/setlocalversion
   - add a tool to generate compile_commands.json from .*.cmd files"

* tag 'kbuild-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (51 commits)
  kbuild: remove unused cmd_gentimeconst
  kbuild: remove $(obj)/ prefixes in ./Kbuild
  treewide: add intermediate .s files to targets
  treewide: remove explicit rules for *offsets.s
  firmware: refactor firmware/Makefile
  firmware: remove unnecessary patterns from .gitignore
  scripts: remove unnecessary ihex2fw and check-lc_ctypes from .gitignore
  um: remove unused filechk_gen_header in Makefile
  scripts: add a tool to produce a compile_commands.json file
  kbuild: add -Werror=implicit-int flag unconditionally
  kbuild: add -Werror=strict-prototypes flag unconditionally
  kbuild: add -fno-PIE flag unconditionally
  scripts: coccinelle: Correct warning message
  scripts: coccinelle: only suggest true/false in files that already use them
  kbuild: handle part-of-module correctly for *.ll and *.symtypes
  kbuild: refactor part-of-module
  kbuild: refactor quiet_modtag
  kbuild: remove redundant quiet_modtag for $(obj-m)
  kbuild: refactor Makefile.asm-generic
  user/Makefile: Fix typo and capitalization in comment section
  ...

Documentation/kbuild/kbuild.txt

@@ -81,12 +81,7 @@ KBUILD_EXTMOD
 --------------------------------------------------
 Set the directory to look for the kernel source when building external
 modules.
-The directory can be specified in several ways:
-1) Use "M=..." on the command line
-2) Environment variable KBUILD_EXTMOD
-3) Environment variable SUBDIRS
-The possibilities are listed in the order they take precedence.
-Using "M=..." will always override the others.
+Setting "M=..." takes precedence over KBUILD_EXTMOD.
 
 KBUILD_OUTPUT
 --------------------------------------------------

Kbuild

@@ -16,11 +16,7 @@ bounds-file := include/generated/bounds.h
 always  := $(bounds-file)
 targets := kernel/bounds.s
 
-# We use internal kbuild rules to avoid the "is up to date" message from make
-kernel/bounds.s: kernel/bounds.c FORCE
-	$(call if_changed_dep,cc_s_c)
-
-$(obj)/$(bounds-file): kernel/bounds.s FORCE
+$(bounds-file): kernel/bounds.s FORCE
 	$(call filechk,offsets,__LINUX_BOUNDS_H__)
 
 #####
@@ -30,15 +26,11 @@ timeconst-file := include/generated/timeconst.h
 
 targets += $(timeconst-file)
 
-quiet_cmd_gentimeconst = GEN     $@
-define cmd_gentimeconst
-	(echo $(CONFIG_HZ) | bc -q $< ) > $@
-endef
 define filechk_gentimeconst
 	(echo $(CONFIG_HZ) | bc -q $< )
 endef
 
-$(obj)/$(timeconst-file): kernel/time/timeconst.bc FORCE
+$(timeconst-file): kernel/time/timeconst.bc FORCE
 	$(call filechk,gentimeconst)
 
 #####
@@ -50,12 +42,9 @@ offsets-file := include/generated/asm-offsets.h
 always  += $(offsets-file)
 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 
-# We use internal kbuild rules to avoid the "is up to date" message from make
-arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
-                                      $(obj)/$(timeconst-file) $(obj)/$(bounds-file) FORCE
-	$(call if_changed_dep,cc_s_c)
+arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file)
 
-$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
+$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
 	$(call filechk,offsets,__ASM_OFFSETS_H__)
 
 #####
@@ -77,7 +66,7 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
 
 extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py
 
-build_constants_py: $(obj)/$(timeconst-file) $(obj)/$(bounds-file)
+build_constants_py: $(timeconst-file) $(bounds-file)
 	@$(MAKE) $(build)=scripts/gdb/linux $@
 
 # Keep these three files during make clean

Makefile

@@ -186,6 +186,10 @@ endif
 # Old syntax make ... SUBDIRS=$PWD is still supported
 # Setting the environment variable KBUILD_EXTMOD take precedence
 ifdef SUBDIRS
+  $(warning ================= WARNING ================)
+  $(warning 'SUBDIRS' will be removed after Linux 5.3)
+  $(warning Please use 'M=' or 'KBUILD_EXTMOD' instead)
+  $(warning ==========================================)
   KBUILD_EXTMOD ?= $(SUBDIRS)
 endif
 
@@ -422,10 +426,10 @@ LINUXINCLUDE    := \
 		-I$(objtree)/include \
 		$(USERINCLUDE)
 
-KBUILD_AFLAGS   := -D__ASSEMBLY__
-KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-		   -fno-strict-aliasing -fno-common -fshort-wchar \
-		   -Werror-implicit-function-declaration \
+KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE
+KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
+		   -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
+		   -Werror-implicit-function-declaration -Werror=implicit-int \
 		   -Wno-format-security \
 		   -std=gnu89
 KBUILD_CPPFLAGS := -D__KERNEL__
@@ -487,18 +491,18 @@ endif
 
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
 ifneq ($(CROSS_COMPILE),)
-CLANG_TARGET	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
+CLANG_FLAGS	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
-CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)
+CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif
 ifneq ($(GCC_TOOLCHAIN),)
-CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)
+CLANG_FLAGS	+= --gcc-toolchain=$(GCC_TOOLCHAIN)
 endif
-KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
-KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
-KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
-KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
+CLANG_FLAGS	+= -no-integrated-as
+KBUILD_CFLAGS	+= $(CLANG_FLAGS)
+KBUILD_AFLAGS	+= $(CLANG_FLAGS)
+export CLANG_FLAGS
 endif
 
 RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
@@ -510,9 +514,6 @@ RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc
 export RETPOLINE_CFLAGS
 export RETPOLINE_VDSO_CFLAGS
 
-KBUILD_CFLAGS	+= $(call cc-option,-fno-PIE)
-KBUILD_AFLAGS	+= $(call cc-option,-fno-PIE)
-
 # check for 'asm goto'
 ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
   CC_HAVE_ASM_GOTO := 1
@@ -828,12 +829,6 @@ KBUILD_CFLAGS  += $(call cc-option,-fno-stack-check,)
 # conserve stack if available
 KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)
 
-# disallow errors like 'EXPORT_GPL(foo);' with missing header
-KBUILD_CFLAGS   += $(call cc-option,-Werror=implicit-int)
-
-# require functions to have arguments in prototypes, not empty 'int foo()'
-KBUILD_CFLAGS   += $(call cc-option,-Werror=strict-prototypes)
-
 # Prohibit date/time macros, which would make the build non-deterministic
 KBUILD_CFLAGS   += $(call cc-option,-Werror=date-time)
 
@@ -1026,14 +1021,13 @@ cmd_link-vmlinux =                                                 \
 	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 
 vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
-ifdef CONFIG_HEADERS_CHECK
-	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
-endif
 ifdef CONFIG_GDB_SCRIPTS
 	$(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
 endif
 	+$(call if_changed,link-vmlinux)
 
+targets := vmlinux
+
 # Build samples along the rest of the kernel. This needs headers_install.
 ifdef CONFIG_SAMPLES
 vmlinux-dirs += samples
@@ -1051,7 +1045,7 @@ $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
 # Error messages still appears in the original language
 
 PHONY += $(vmlinux-dirs)
-$(vmlinux-dirs): prepare scripts
+$(vmlinux-dirs): prepare
 	$(Q)$(MAKE) $(build)=$@ need-builtin=1
 
 define filechk_kernel.release
@@ -1066,7 +1060,7 @@ include/config/kernel.release: $(srctree)/Makefile FORCE
 # Carefully list dependencies so we do not try to build scripts twice
 # in parallel
 PHONY += scripts
-scripts: scripts_basic scripts_dtc asm-generic gcc-plugins $(autoksyms_h)
+scripts: scripts_basic scripts_dtc
 	$(Q)$(MAKE) $(build)=$(@)
 
 # Things we need to do before we recursively start building the kernel
@@ -1099,22 +1093,23 @@ prepare2: prepare3 outputmakefile asm-generic
 prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h
 	$(cmd_crmodverdir)
 
-archprepare: archheaders archscripts prepare1 scripts_basic
+archprepare: archheaders archscripts prepare1 scripts
 
-prepare0: archprepare gcc-plugins
+prepare0: archprepare
+	$(Q)$(MAKE) $(build)=scripts/mod
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
 prepare: prepare0 prepare-objtool
 
 # Support for using generic headers in asm-generic
+asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
+
 PHONY += asm-generic uapi-asm-generic
 asm-generic: uapi-asm-generic
-	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
-	            src=asm obj=arch/$(SRCARCH)/include/generated/asm
+	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm
 uapi-asm-generic:
-	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
-	            src=uapi/asm obj=arch/$(SRCARCH)/include/generated/uapi/asm
+	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm
 
 PHONY += prepare-objtool
 prepare-objtool: $(objtool_target)
@@ -1199,6 +1194,10 @@ headers_check: headers_install
 	$(Q)$(MAKE) $(hdr-inst)=include/uapi dst=include HDRCHECK=1
 	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi $(hdr-dst) HDRCHECK=1
 
+ifdef CONFIG_HEADERS_CHECK
+all: headers_check
+endif
+
 # ---------------------------------------------------------------------------
 # Kernel selftest
 
@@ -1283,7 +1282,7 @@ modules.builtin: $(vmlinux-dirs:%=%/modules.builtin)
 
 # Target to prepare building external modules
 PHONY += modules_prepare
-modules_prepare: prepare scripts
+modules_prepare: prepare
 
 # Target to install modules
 PHONY += modules_install
@@ -1551,9 +1550,6 @@ else # KBUILD_EXTMOD
 
 # We are always building modules
 KBUILD_MODULES := 1
-PHONY += crmodverdir
-crmodverdir:
-	$(cmd_crmodverdir)
 
 PHONY += $(objtree)/Module.symvers
 $(objtree)/Module.symvers:
@@ -1565,7 +1561,7 @@ $(objtree)/Module.symvers:
 
 module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))
 PHONY += $(module-dirs) modules
-$(module-dirs): crmodverdir $(objtree)/Module.symvers
+$(module-dirs): prepare $(objtree)/Module.symvers
 	$(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)
 
 modules: $(module-dirs)
@@ -1604,10 +1600,9 @@ help:
 	@echo  '  clean           - remove generated files in module directory only'
 	@echo  ''
 
-# Dummies...
-PHONY += prepare scripts
-prepare: ;
-scripts: ;
+PHONY += prepare
+prepare:
+	$(cmd_crmodverdir)
 endif # KBUILD_EXTMOD
 
 clean: $(clean-dirs)
@@ -1712,36 +1707,33 @@ else
         target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
 endif
 
-%.s: %.c prepare scripts FORCE
+%.s: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.i: %.c prepare scripts FORCE
+%.i: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.c prepare scripts FORCE
+%.o: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.lst: %.c prepare scripts FORCE
+%.lst: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.s: %.S prepare scripts FORCE
+%.s: %.S prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: %.S prepare scripts FORCE
+%.o: %.S prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.symtypes: %.c prepare scripts FORCE
+%.symtypes: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.ll: %.c prepare scripts FORCE
+%.ll: %.c prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 
 # Modules
-/: prepare scripts FORCE
-	$(cmd_crmodverdir)
+/: prepare FORCE
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
 	$(build)=$(build-dir)
 # Make sure the latest headers are built for Documentation
 Documentation/ samples/: headers_install
-%/: prepare scripts FORCE
-	$(cmd_crmodverdir)
+%/: prepare FORCE
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
 	$(build)=$(build-dir)
-%.ko: prepare scripts FORCE
-	$(cmd_crmodverdir)
+%.ko: prepare FORCE
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
 	$(build)=$(build-dir) $(@:.ko=.o)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
@@ -1765,13 +1757,12 @@ quiet_cmd_depmod = DEPMOD  $(KERNELRELEASE)
 cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
                   $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)
 
-# read all saved command lines
-cmd_files := $(wildcard .*.cmd)
+# read saved command lines for existing targets
+existing-targets := $(wildcard $(sort $(targets)))
 
-ifneq ($(cmd_files),)
-  $(cmd_files): ;	# Do not try to update included dependency files
-  include $(cmd_files)
-endif
+cmd_files := $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
+$(cmd_files): ;	# Do not try to update included dependency files
+-include $(cmd_files)
 
 endif   # ifeq ($(config-targets),1)
 endif   # ifeq ($(mixed-targets),1)

arch/arm/crypto/Makefile

@@ -67,4 +67,4 @@ $(src)/sha512-core.S_shipped: $(src)/sha512-armv4.pl
 	$(call cmd,perl)
 endif
 
-targets += sha256-core.S sha512-core.S
+clean-files += sha256-core.S sha512-core.S

arch/arm/mach-at91/Makefile

@@ -19,10 +19,9 @@ ifeq ($(CONFIG_PM_DEBUG),y)
 CFLAGS_pm.o += -DDEBUG
 endif
 
-arch/arm/mach-at91/pm_data-offsets.s: arch/arm/mach-at91/pm_data-offsets.c
-	$(call if_changed_dep,cc_s_c)
-
 include/generated/at91_pm_data-offsets.h: arch/arm/mach-at91/pm_data-offsets.s FORCE
 	$(call filechk,offsets,__PM_DATA_OFFSETS_H__)
 
 arch/arm/mach-at91/pm_suspend.o: include/generated/at91_pm_data-offsets.h
+
+targets += pm_data-offsets.s

arch/arm/mach-omap2/Makefile

@@ -236,10 +236,9 @@ obj-y					+= omap_phy_internal.o
 
 obj-$(CONFIG_MACH_OMAP2_TUSB6010)	+= usb-tusb6010.o
 
-arch/arm/mach-omap2/pm-asm-offsets.s: arch/arm/mach-omap2/pm-asm-offsets.c
-	$(call if_changed_dep,cc_s_c)
-
 include/generated/ti-pm-asm-offsets.h: arch/arm/mach-omap2/pm-asm-offsets.s FORCE
 	$(call filechk,offsets,__TI_PM_ASM_OFFSETS_H__)
 
 $(obj)/sleep33xx.o $(obj)/sleep43xx.o: include/generated/ti-pm-asm-offsets.h
+
+targets += pm-asm-offsets.s

arch/arm64/crypto/Makefile

@@ -78,4 +78,4 @@ $(src)/sha512-core.S_shipped: $(src)/sha512-armv8.pl
 	$(call cmd,perlasm)
 endif
 
-targets += sha256-core.S sha512-core.S
+clean-files += sha256-core.S sha512-core.S

arch/ia64/kernel/Makefile

@@ -50,10 +50,7 @@ CFLAGS_traps.o  += -mfixed-range=f2-f5,f16-f31
 # The gate DSO image is built using a special linker script.
 include $(src)/Makefile.gate
 
-# We use internal kbuild rules to avoid the "is up to date" message from make
-arch/$(SRCARCH)/kernel/nr-irqs.s: arch/$(SRCARCH)/kernel/nr-irqs.c
-	$(Q)mkdir -p $(dir $@)
-	$(call if_changed_dep,cc_s_c)
-
 include/generated/nr-irqs.h: arch/$(SRCARCH)/kernel/nr-irqs.s FORCE
 	$(call filechk,offsets,__ASM_NR_IRQS_H__)
+
+targets += nr-irqs.s

arch/powerpc/boot/Makefile

@@ -55,6 +55,11 @@ BOOTAFLAGS	:= -D__ASSEMBLY__ $(BOOTCFLAGS) -traditional -nostdinc
 
 BOOTARFLAGS	:= -cr$(KBUILD_ARFLAGS)
 
+ifdef CONFIG_CC_IS_CLANG
+BOOTCFLAGS += $(CLANG_FLAGS)
+BOOTAFLAGS += $(CLANG_FLAGS)
+endif
+
 ifdef CONFIG_DEBUG_INFO
 BOOTCFLAGS	+= -g
 endif