Merge patch series "Update kbuild"

Ilias Apalodimas <ilias.apalodimas@linaro.org> says:

Last time the kbuild scripts were synced with the Linux kernel was on the
4.20 release. Updating directly to 6.x makes the diff difficult to read, so
let's do the changes incrementally and bump to 5.1 first.

Since the number of commits is big, I am splitting this in multiple series.
This one includes most of the commits for Makefile.build,
Makefile.lib and some from Makefile.

commit eeb5687a7139649e ("kbuild: add -Werror=strict-prototypes flag unconditionally")
commit 3812b8c5c5d5 ("kbuild: make -r/-R effective in top Makefile for old Make versions")
commit b421b8a6cb87 ("kbuild: remove unused archmrproper")
commit 1a49b2fd8f58 ("kbuild: strip whitespace in cmd_record_mcount findstring")
commit 88110713ca9dfb ("kbuild: hardcode genksyms path and remove GENKSYMS variable")
commit 1d8001ef358 ("kbuild: generate modules.order only when CONFIG_MODULES=y")
commit 45c4372d00 ("kbuild: refactor quiet_modtag")
commit b39a691617e4 commit ("kbuild: remove redundant quiet_modtag for $(obj-m)")
commit 5439f09f488f ("kbuild: remove redundant 'set -e' from cmd_* defines")
commit e5d289100d3a ("kbuild: remove trailing semicolon from cmd_* passed to if_changed_rule")
commit 3a2429e1faf4 ("kbuild: change if_changed_rule for multi-line recipe")
commit ee3e46b7efd2 ("kbuild: refactor modversions build rules")
commit 4317ee3b6a5e ("kbuild: remove redundant 'set -e' from sub_cmd_record_mcount")
commit 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files")
commit 898f5a009f22 ("kbuild: move archive command to scripts/Makefile.lib")
commit b79c6aa6a1f1 ("kbuild: remove unnecessary in-subshell execution")
commit afa974b77128 ("kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)")
commit ecbd10d90e94 ("kbuild: simplify rules of data compression with size appending")
commit 58156ba4468f ("kbuild: skip 'addtree' and 'flags' magic for external module build")
commit 172caf1993b7 ("kbuild: remove redundant target cleaning on failure")
commit f3fd4a3f3a38 ("kbuild: remove redundant 'set -e' from filechk_offsets")
commit a2237fec1e06 ("kbuild: Enable dtc graph_port warning by default")
commit 70523a3ce5ff ("kbuild: disable dtc simple_bus_reg warnings by default")
commit e4aca4595005 ("kbuild: de-duplicate fixdep usage")

Link: https://lore.kernel.org/r/20250520052153.307194-1-ilias.apalodimas@linaro.org

5 files changed, 113 insertions, 122 deletions

diff --git a/Makefile b/Makefile
index f88684947ee..c7b82299c19 100644
--- a/Makefile
+++ b/Makefile
@@ -12,10 +12,6 @@ NAME =
 # Comments in this file are targeted only to the developer, do not
 # expect to learn how to build the kernel reading this file.
 
-# Do not use make's built-in rules and variables
-# (this increases performance and avoids hard-to-debug behaviour)
-MAKEFLAGS += -rR
-
 # Determine target architecture for the sandbox
 include include/host_arch.h
 ifeq ("", "$(CROSS_COMPILE)")
@@ -39,15 +35,6 @@ else ifeq ("riscv64", $(MK_ARCH))
 endif
 undefine MK_ARCH
 
-# Avoid funny character set dependencies
-unexport LC_ALL
-LC_COLLATE=C
-LC_NUMERIC=C
-export LC_COLLATE LC_NUMERIC
-
-# Avoid interference with shell env settings
-unexport GREP_OPTIONS
-
 # We are using a recursive build, so we need to do a little thinking
 # to get the ordering right.
 #
@@ -64,6 +51,21 @@ unexport GREP_OPTIONS
 # descending is started. They are now explicitly listed as the
 # prepare rule.
 
+ifneq ($(sub-make-done),1)
+
+# Do not use make's built-in rules and variables
+# (this increases performance and avoids hard-to-debug behaviour)
+MAKEFLAGS += -rR
+
+# Avoid funny character set dependencies
+unexport LC_ALL
+LC_COLLATE=C
+LC_NUMERIC=C
+export LC_COLLATE LC_NUMERIC
+
+# Avoid interference with shell env settings
+unexport GREP_OPTIONS
+
 # Beautify output
 # ---------------------------------------------------------------------------
 #
@@ -137,7 +139,6 @@ export quiet Q KBUILD_VERBOSE
 
 # KBUILD_SRC is set on invocation of make in OBJ directory
 # KBUILD_SRC is not intended to be used by the regular user (for now)
-ifeq ($(KBUILD_SRC),)
 
 # OK, Make called in directory where kernel src resides
 # Do we want to locate output files in a separate directory?
@@ -168,22 +169,25 @@ $(if $(KBUILD_OUTPUT),, \
 # 'sub-make' below.
 MAKEFLAGS += --include-dir=$(CURDIR)
 
+else
+
+# Do not print "Entering directory ..." at all for in-tree build.
+MAKEFLAGS += --no-print-directory
+
+endif # ifneq ($(KBUILD_OUTPUT),)
+
 PHONY += $(MAKECMDGOALS) sub-make
 
 $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
 	@:
 
 sub-make: FORCE
-	$(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \
+	$(Q)$(MAKE) sub-make-done=1 \
+	$(if $(KBUILD_OUTPUT),-C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR)) \
 	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
 
-# Leave processing to above invocation of make
-skip-makefile := 1
-endif # ifneq ($(KBUILD_OUTPUT),)
-endif # ifeq ($(KBUILD_SRC),)
-
+else # sub-make-done
 # We process the rest of the Makefile if this is the final invocation of make
-ifeq ($(skip-makefile),)
 
 # Do not print "Entering directory ...",
 # but we want to display it when entering to the output directory
@@ -429,7 +433,7 @@ CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
 
 KBUILD_CPPFLAGS := -D__KERNEL__ -D__UBOOT__
 
-KBUILD_CFLAGS   := -Wall -Wstrict-prototypes \
+KBUILD_CFLAGS   := -Wall -Werror=strict-prototypes -Wno-trigraphs \
 		   -Wno-format-security \
 		   -fno-builtin -ffreestanding $(CSTD_FLAG)
 KBUILD_CFLAGS	+= -fshort-wchar -fno-strict-aliasing
@@ -2281,7 +2285,7 @@ mrproper: rm-dirs  := $(wildcard $(MRPROPER_DIRS))
 mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
 mrproper-dirs      := $(addprefix _mrproper_,scripts)
 
-PHONY += $(mrproper-dirs) mrproper archmrproper
+PHONY += $(mrproper-dirs) mrproper
 $(mrproper-dirs):
 	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
 
@@ -2539,18 +2543,15 @@ quiet_cmd_rmdirs = $(if $(wildcard $(rm-dirs)),CLEAN   $(wildcard $(rm-dirs)))
 quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
       cmd_rmfiles = rm -f $(rm-files)
 
-# read all saved command lines
-
-cmd_files := $(wildcard .*.cmd)
-
-ifneq ($(cmd_files),)
-  $(cmd_files): ;	# Do not try to update included dependency files
-  include $(cmd_files)
-endif
+# read saved command lines for existing targets
+existing-targets := $(wildcard $(sort $(targets)))
+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)
-endif	# skip-makefile
+endif	 # sub-make-done
 
 PHONY += FORCE
 FORCE:
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 054dd157485..c0d3440a4b3 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -28,6 +28,10 @@ basetarget = $(basename $(notdir $@))
 baseprereq = $(basename $(notdir $<))
 
 ###
+# real prerequisites without phony targets
+real-prereqs = $(filter-out $(PHONY), $^)
+
+###
 # Escape single quote for use in echo statements
 escsq = $(subst $(squote),'\$(squote)',$1)
 
@@ -222,7 +226,7 @@ echo-cmd = $(if $($(quiet)cmd_$(1)),\
 	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
 
 # printing commands
-cmd = @$(echo-cmd) $(cmd_$(1))
+cmd = @set -e; $(echo-cmd) $(cmd_$(1))
 
 # Add $(obj)/ for paths that are not absolute
 objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
@@ -264,19 +268,17 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
 	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
 
 # Execute the command and also postprocess generated .d dependencies file.
-if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
-	@set -e;                                                             \
-	$(echo-cmd) $(cmd_$(1));                                             \
-	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
-	rm -f $(depfile);                                                    \
-	mv -f $(dot-target).tmp $(dot-target).cmd, @:)
+if_changed_dep = $(if $(strip $(any-prereq) $(arg-check)),$(cmd_and_fixdep),@:)
+
+cmd_and_fixdep =						             \
+	$(cmd);							             \
+	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
+	rm -f $(depfile)
 
 # Usage: $(call if_changed_rule,foo)
 # Will check if $(cmd_foo) or any of the prerequisites changed,
 # and if so will execute $(rule_foo).
-if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
-	@set -e;                                                             \
-	$(rule_$(1)), @:)
+if_changed_rule = $(if $(strip $(any-prereq) $(arg-check)),$(rule_$(1)),@:)
 
 ###
 # why - tell why a a target got build
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 90aed148c44..aa48d249433 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -82,7 +82,9 @@ ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
 builtin-target := $(obj)/built-in.o
 endif
 
+ifdef CONFIG_MODULES
 modorder-target := $(obj)/modules.order
+endif
 
 # We keep a list of all modules in $(MODVERDIR)
 
@@ -94,10 +96,10 @@ __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
 # Linus' kernel sanity checking tool
 ifeq ($(KBUILD_CHECKSRC),1)
   quiet_cmd_checksrc       = CHECK   $<
-        cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
+        cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 else ifeq ($(KBUILD_CHECKSRC),2)
   quiet_cmd_force_checksrc = CHECK   $<
-        cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
+        cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 endif
 
 # Do section mismatch analysis for each module/built-in.o
@@ -113,20 +115,13 @@ modkern_cflags =                                          \
 	$(if $(part-of-module),                           \
 		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
 		$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
-quiet_modtag := $(empty)   $(empty)
+quiet_modtag = $(if $(part-of-module),[M],   )
 
 $(real-objs-m)        : part-of-module := y
 $(real-objs-m:.o=.i)  : part-of-module := y
 $(real-objs-m:.o=.s)  : part-of-module := y
 $(real-objs-m:.o=.lst): part-of-module := y
 
-$(real-objs-m)        : quiet_modtag := [M]
-$(real-objs-m:.o=.i)  : quiet_modtag := [M]
-$(real-objs-m:.o=.s)  : quiet_modtag := [M]
-$(real-objs-m:.o=.lst): quiet_modtag := [M]
-
-$(obj-m)              : quiet_modtag := [M]
-
 # Default for not multi-part modules
 modname = $(basetarget)
 
@@ -153,13 +148,12 @@ $(obj)/%.i: $(src)/%.c FORCE
 
 cmd_gensymtypes =                                                           \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
-    $(GENKSYMS) $(if $(1), -T $(2))                                         \
+    scripts/genksyms/genksyms $(if $(1), -T $(2))			    \
      $(if $(KBUILD_PRESERVE),-p)                                            \
      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 
 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 cmd_cc_symtypes_c =                                                         \
-    set -e;                                                                 \
     $(call cmd_gensymtypes,true,$@) >/dev/null;                             \
     test -s $@ || rm -f $@
 
@@ -171,34 +165,30 @@ $(obj)/%.symtypes : $(src)/%.c FORCE
 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
 
 quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
-
-ifndef CONFIG_MODVERSIONS
 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
-else
+ifdef CONFIG_MODVERSIONS
 # When module versioning is enabled the following steps are executed:
-# o compile a .tmp_<file>.o from <file>.c
-# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
-#   not export symbols, we just rename .tmp_<file>.o to <file>.o and
-#   are done.
+# o compile a <file>.o from <file>.c
+# o if <file>.o doesn't contain a __ksymtab version, i.e. does
+#   not export symbols, it's done
 # o otherwise, we calculate symbol versions using the good old
 #   genksyms on the preprocessed source and postprocess them in a way
 #   that they are usable as a linker script
-# o generate <file>.o from .tmp_<file>.o using the linker to
+# o generate .tmp_<file>.o from <file>.o using the linker to
 #   replace the unresolved symbols __crc_exported_symbol with
 #   the actual value of the checksum generated by genksyms
 
-cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
+# o remove .tmp_<file>.o to <file>.o
 cmd_modversions =								\
-	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
+	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
 		$(call cmd_gensymtypes,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
 		    > $(@D)/.tmp_$(@F:.o=.ver);					\
 										\
-		$(LD) $(KBUILD_LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 		\
+		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@		\
 			-T $(@D)/.tmp_$(@F:.o=.ver);				\
-		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
-	else									\
 		mv -f $(@D)/.tmp_$(@F) $@;					\
+		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
 	fi;
 endif
 
@@ -223,7 +213,7 @@ sub_cmd_record_mcount =					\
 recordmcount_source := $(srctree)/scripts/recordmcount.c \
 		    $(srctree)/scripts/recordmcount.h
 else
-sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)"	\
 	"$(if $(CONFIG_SYS_BIG_ENDIAN),big,little)" \
 	"$(if $(CONFIG_64BIT),64,32)" \
 	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
@@ -231,24 +221,26 @@ sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH
 	"$(if $(part-of-module),1,0)" "$(@)";
 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 endif
-cmd_record_mcount =						\
-	if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =	\
-	     "$(CC_FLAGS_FTRACE)" ]; then			\
-		$(sub_cmd_record_mcount)			\
-	fi;
+cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),        \
+       $(sub_cmd_record_mcount))
 endif # -record-mcount
 endif
 
 define rule_cc_o_c
-	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
-	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
-	$(cmd_modversions)						  \
-	$(call echo-cmd,record_mcount)					  \
-	$(cmd_record_mcount)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
-	                                              $(dot-target).tmp;  \
-	rm -f $(depfile);						  \
-	mv -f $(dot-target).tmp $(dot-target).cmd
+	$(call cmd,checksrc)
+	$(call cmd_and_fixdep,cc_o_c)
+	$(call cmd,gen_ksymdeps)
+	$(call cmd,checkdoc)
+	$(call cmd,objtool)
+	$(call cmd,modversions_c)
+	$(call cmd,record_mcount)
+endef
+
+define rule_as_o_S
+	$(call cmd_and_fixdep,as_o_S)
+	$(call cmd,gen_ksymdeps)
+	$(call cmd,objtool)
+	$(call cmd,modversions_S)
 endef
 
 # Built-in and composite module parts
@@ -352,11 +344,9 @@ $(modorder-target): $(subdir-ym) FORCE
 # Rule to compile a set of .o files into one .a file
 #
 ifdef lib-target
-quiet_cmd_link_l_target = AR      $@
-cmd_link_l_target = rm -f $@; $(AR) cDPrsT$(KBUILD_ARFLAGS) $@ $(lib-y)
 
 $(lib-target): $(lib-y) FORCE
-	$(call if_changed,link_l_target)
+	$(call if_changed,ar)
 
 targets += $(lib-target)
 endif
@@ -409,14 +399,17 @@ FORCE:
 # optimization, we don't need to read them if the target does not
 # exist, we will rebuild anyway in that case.
 
-cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
+existing-targets := $(wildcard $(sort $(targets)))
 
-ifneq ($(cmd_files),)
-  include $(cmd_files)
-endif
+-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 
 # Create directories for object files if they do not exist
 obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
+# If targets exist, their directories apparently exist. Skip mkdir.
+existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
+obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
+ifneq ($(obj-dirs),)
 $(shell mkdir -p $(obj-dirs))
+endif
 
 .PHONY: $(PHONY)
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 7624304e3e9..bd5ed4c63b7 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -72,13 +72,15 @@ _hostc_flags   = $(KBUILD_HOSTCFLAGS)   $(HOST_EXTRACFLAGS)   \
 _hostcxx_flags = $(KBUILD_HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
                  $(HOSTCXXFLAGS_$(basetarget).o)
 
-ifeq ($(KBUILD_SRC),)
 __hostc_flags	= $(_hostc_flags)
 __hostcxx_flags	= $(_hostcxx_flags)
-else
+
+ifeq ($(KBUILD_EXTMOD),)
+ifneq ($(KBUILD_SRC),)
 __hostc_flags	= -I$(obj) $(call flags,_hostc_flags)
 __hostcxx_flags	= -I$(obj) $(call flags,_hostcxx_flags)
 endif
+endif
 
 hostc_flags    = -Wp,-MD,$(depfile) $(__hostc_flags)
 hostcxx_flags  = -Wp,-MD,$(depfile) $(__hostcxx_flags)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index e89a4a51b74..acf780fdd45 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -143,15 +143,14 @@ _c_flags += $(if $(patsubst n%,, \
 		$(CFLAGS_KASAN))
 endif
 
-# If building the kernel in a separate objtree expand all occurrences
-# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
-
-ifeq ($(KBUILD_SRC),)
 __c_flags	= $(_c_flags)
 __a_flags	= $(_a_flags)
 __cpp_flags     = $(_cpp_flags)
-else
 
+# If building the kernel in a separate objtree expand all occurrences
+# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
+ifeq ($(KBUILD_EXTMOD),)
+ifneq ($(KBUILD_SRC),)
 # -I$(obj) locates generated .h files
 # $(call addtree,-I$(obj)) locates .h files in srctree, from generated .c files
 #   and locates generated .h files
@@ -161,6 +160,7 @@ __c_flags	= $(if $(obj),$(call addtree,-I$(src)) -I$(obj)) \
 __a_flags	= $(call flags,_a_flags)
 __cpp_flags     = $(call flags,_cpp_flags)
 endif
+endif
 
 # Modified for U-Boot: LINUXINCLUDE -> UBOOTINCLUDE
 c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(UBOOTINCLUDE)     \
@@ -278,6 +278,11 @@ $(obj)/%: $(src)/%_shipped
 quiet_cmd_ld = LD      $@
 cmd_ld = $(LD) $(ld_flags) $(filter-out FORCE,$^) -o $@
 
+# Archive
+# ---------------------------------------------------------------------------
+quiet_cmd_ar = AR      $@
+cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
+
 # Objcopy
 # ---------------------------------------------------------------------------
 
@@ -288,8 +293,7 @@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 # ---------------------------------------------------------------------------
 
 quiet_cmd_gzip = GZIP    $@
-cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@) || \
-	(rm -f $@ ; false)
+cmd_gzip = cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@
 
 # DTC
 # ---------------------------------------------------------------------------
@@ -301,7 +305,7 @@ DTC_FLAGS += -Wno-unit_address_vs_reg \
 	-Wno-avoid_unnecessary_addr_size \
 	-Wno-alias_paths \
 	-Wno-graph_child_address \
-	-Wno-graph_port \
+	-Wno-simple_bus_reg \
 	-Wno-unique_unit_address \
 	-Wno-simple_bus_reg \
 	-Wno-pci_device_reg
@@ -325,7 +329,7 @@ DTC_FLAGS += $(if $(filter $(patsubst $(obj)/%,%,$@), $(base-dtb-y)), -@)
 quiet_cmd_dt_S_dtb= DTBS    $@
 # Modified for U-Boot
 cmd_dt_S_dtb=						\
-(							\
+{							\
 	echo '.section .dtb.init.rodata,"a"';		\
 	echo '.balign 16';				\
 	echo '.global __dtb_$(subst -,_,$(*F))_begin';	\
@@ -334,7 +338,7 @@ cmd_dt_S_dtb=						\
 	echo '__dtb_$(subst -,_,$(*F))_end:';		\
 	echo '.global __dtb_$(subst -,_,$(*F))_end';	\
 	echo '.balign 16';				\
-) > $@
+} > $@
 
 $(obj)/%.dtb.S: $(obj)/%.dtb
 	$(call cmd,dt_S_dtb)
@@ -547,7 +551,7 @@ $(obj)/dsdt_generated.c:    $(src)/dsdt.asl
 # append the size as a 32-bit littleendian number as gzip does.
 size_append = printf $(shell						\
 dec_size=0;								\
-for F in $1; do								\
+for F in $(real-prereqs); do
 	fsize=$$(stat -c "%s" $$F);					\
 	dec_size=$$(expr $$dec_size + $$fsize);				\
 done;									\
@@ -561,27 +565,20 @@ printf "%08x\n" $$dec_size |						\
 )
 
 quiet_cmd_bzip2 = BZIP2   $@
-cmd_bzip2 = (cat $(filter-out FORCE,$^) | \
-	bzip2 -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
-	(rm -f $@ ; false)
+cmd_bzip2 = { cat $(real-prereqs) | bzip2 -9 && $(size_append); } > $@
 
 # Lzma
 # ---------------------------------------------------------------------------
 
 quiet_cmd_lzma = LZMA    $@
-cmd_lzma = (cat $(filter-out FORCE,$^) | \
-	lzma -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
-	(rm -f $@ ; false)
+cmd_lzma = { cat $(real-prereqs) | lzma -9 && $(size_append); } > $@
 
 quiet_cmd_lzo = LZO     $@
-cmd_lzo = (cat $(filter-out FORCE,$^) | \
-	lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
-	(rm -f $@ ; false)
+cmd_lzo = { cat $(real-prereqs) | lzop -9 && $(size_append); } > $@
 
 quiet_cmd_lz4 = LZ4     $@
-cmd_lz4 = (cat $(filter-out FORCE,$^) | \
-	lz4c -l -c1 stdin stdout && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
-	(rm -f $@ ; false)
+cmd_lz4 = { cat $(real-prereqs) | lz4c -l -c1 stdin stdout && \
+	$(size_append); } > $@
 
 # U-Boot mkimage
 # ---------------------------------------------------------------------------
@@ -625,15 +622,11 @@ quiet_cmd_uimage = UIMAGE  $(UIMAGE_OUT)
 # big dictionary would increase the memory usage too much in the multi-call
 # decompression mode. A BCJ filter isn't used either.
 quiet_cmd_xzkern = XZKERN  $@
-cmd_xzkern = (cat $(filter-out FORCE,$^) | \
-	sh $(srctree)/scripts/xz_wrap.sh && \
-	$(call size_append, $(filter-out FORCE,$^))) > $@ || \
-	(rm -f $@ ; false)
+cmd_xzkern = { cat $(filter-out FORCE,$^) | \
+	sh $(srctree)/scripts/xz_wrap.sh && $(size_append); } > $@
 
 quiet_cmd_xzmisc = XZMISC  $@
-cmd_xzmisc = (cat $(filter-out FORCE,$^) | \
-	xz --check=crc32 --lzma2=dict=1MiB) > $@ || \
-	(rm -f $@ ; false)
+cmd_xzmisc = cat $(real-prereqs) | xz --check=crc32 --lzma2=dict=1MiB > $@
 
 # Additional commands for U-Boot
 #
@@ -718,7 +711,7 @@ endef
 # Use filechk to avoid rebuilds when a header changes, but the resulting file
 # does not
 define filechk_offsets
-	(set -e; \
+	( \
 	 echo "#ifndef $2"; \
 	 echo "#define $2"; \
 	 echo "/*"; \