linux/scripts/Makefile.build

# SPDX-License-Identifier: GPL-2.0
# ==========================================================================
# Building
# ==========================================================================

src := $(obj)

PHONY := __build
__build:

# Init all relevant variables used in kbuild files so
# 1) they have correct type
# 2) they do not inherit any value from the environment
obj-y :=
obj-m :=
lib-y :=
lib-m :=
always :=
targets :=
subdir-y :=
subdir-m :=
EXTRA_AFLAGS   :=
EXTRA_CFLAGS   :=
EXTRA_CPPFLAGS :=
EXTRA_LDFLAGS  :=
asflags-y  :=
ccflags-y  :=
cppflags-y :=
ldflags-y  :=

subdir-asflags-y :=
subdir-ccflags-y :=

# Read auto.conf if it exists, otherwise ignore
-include include/config/auto.conf

include scripts/Kbuild.include

# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
include $(kbuild-file)

include scripts/Makefile.lib

# Do not include host rules unless needed
ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
include scripts/Makefile.host
endif

ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif

# ===========================================================================

ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
lib-target := $(obj)/lib.a
real-obj-y += $(obj)/lib-ksyms.o
endif

ifneq ($(strip $(real-obj-y) $(need-builtin)),)
builtin-target := $(obj)/built-in.a
endif

ifdef CONFIG_MODULES
modorder-target := $(obj)/modules.order
endif

# We keep a list of all modules in $(MODVERDIR)

__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
	 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
	 $(subdir-ym) $(always)
	@:

# Linus' kernel sanity checking tool
ifeq ($(KBUILD_CHECKSRC),1)
  quiet_cmd_checksrc       = CHECK   $<
        cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
else ifeq ($(KBUILD_CHECKSRC),2)
  quiet_cmd_force_checksrc = CHECK   $<
        cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
endif

ifneq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
endif

# Do section mismatch analysis for each module/built-in.a
ifdef CONFIG_DEBUG_SECTION_MISMATCH
  cmd_secanalysis = ; scripts/mod/modpost $@
endif

# Compile C sources (.c)
# ---------------------------------------------------------------------------

# Default is built-in, unless we know otherwise
$(foreach x, i ll lst o s symtypes, $(patsubst %.o,%.$(x),$(real-obj-m))): \
	part-of-module := y

modkern_cflags =                                          \
	$(if $(part-of-module),                           \
		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
		$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
quiet_modtag = $(if $(part-of-module),[M],   )

quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
      cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<

$(obj)/%.s: $(src)/%.c FORCE
	$(call if_changed_dep,cc_s_c)

quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<

$(obj)/%.i: $(src)/%.c FORCE
	$(call if_changed_dep,cpp_i_c)

# These mirror gensymtypes_S and co below, keep them in synch.
cmd_gensymtypes_c =                                                         \
    $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
     $(if $(KBUILD_PRESERVE),-p)                                            \
     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))

quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
cmd_cc_symtypes_c =                                                         \
    $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
    test -s $@ || rm -f $@

$(obj)/%.symtypes : $(src)/%.c FORCE
	$(call cmd,cc_symtypes_c)

# LLVM assembly
# Generate .ll files from .c
quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
      cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<

$(obj)/%.ll: $(src)/%.c FORCE
	$(call if_changed_dep,cc_ll_c)

# C (.c) files
# The C file is compiled and updated dependency information is generated.
# (See cmd_cc_o_c + relevant part of rule_cc_o_c)

quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

ifdef CONFIG_MODVERSIONS
# When module versioning is enabled the following steps are executed:
# 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 .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
# o remove .tmp_<file>.o to <file>.o

cmd_modversions_c =								\
	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
		    > $(@D)/.tmp_$(@F:.o=.ver);					\
										\
		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
			-T $(@D)/.tmp_$(@F:.o=.ver);				\
		mv -f $(@D)/.tmp_$(@F) $@;					\
		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
	fi
endif

ifdef CONFIG_FTRACE_MCOUNT_RECORD
ifndef CC_USING_RECORD_MCOUNT
# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
ifdef BUILD_C_RECORDMCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
  RECORDMCOUNT_FLAGS = -w
endif
# Due to recursion, we must skip empty.o.
# The empty.o file is created in the make process in order to determine
# the target endianness and word size. It is made before all other C
# files, including recordmcount.
sub_cmd_record_mcount =					\
	if [ $(@) != "scripts/mod/empty.o" ]; then	\
		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
	fi;
recordmcount_source := $(srctree)/scripts/recordmcount.c \
		    $(srctree)/scripts/recordmcount.h
else
sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
	"$(if $(CONFIG_64BIT),64,32)" \
	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
	"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
	"$(if $(part-of-module),1,0)" "$(@)";
recordmcount_source := $(srctree)/scripts/recordmcount.pl
endif # BUILD_C_RECORDMCOUNT
cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\
	$(sub_cmd_record_mcount))
endif # CC_USING_RECORD_MCOUNT
endif # CONFIG_FTRACE_MCOUNT_RECORD

ifdef CONFIG_STACK_VALIDATION
ifneq ($(SKIP_STACK_VALIDATION),1)

__objtool_obj := $(objtree)/tools/objtool/objtool

objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)

objtool_args += $(if $(part-of-module), --module,)

ifndef CONFIG_FRAME_POINTER
objtool_args += --no-fp
endif
ifdef CONFIG_GCOV_KERNEL
objtool_args += --no-unreachable
endif
ifdef CONFIG_RETPOLINE
  objtool_args += --retpoline
endif
ifdef CONFIG_X86_SMAP
  objtool_args += --uaccess
endif

# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
cmd_objtool = $(if $(patsubst y%,, \
	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
	$(__objtool_obj) $(objtool_args) $@)
objtool_obj = $(if $(patsubst y%,, \
	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
	$(__objtool_obj))

endif # SKIP_STACK_VALIDATION
endif # CONFIG_STACK_VALIDATION

# Rebuild all objects when objtool changes, or is enabled/disabled.
objtool_dep = $(objtool_obj)					\
	      $(wildcard include/config/orc/unwinder.h		\
			 include/config/stack/validation.h)

ifdef CONFIG_TRIM_UNUSED_KSYMS
cmd_gen_ksymdeps = \
	$(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
endif

define rule_cc_o_c
	$(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

# List module undefined symbols (or empty line if not enabled)
ifdef CONFIG_TRIM_UNUSED_KSYMS
cmd_undef_syms = $(NM) $@ | sed -n 's/^  *U //p' | xargs echo
else
cmd_undef_syms = echo
endif

# Built-in and composite module parts
$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
	$(call cmd,force_checksrc)
	$(call if_changed_rule,cc_o_c)

# Single-part modules are special since we need to mark them in $(MODVERDIR)

$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
	$(call cmd,force_checksrc)
	$(call if_changed_rule,cc_o_c)
	@{ echo $(@:.o=.ko); echo $@; \
	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)

quiet_cmd_cc_lst_c = MKLST   $@
      cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
				     System.map $(OBJDUMP) > $@

$(obj)/%.lst: $(src)/%.c FORCE
	$(call if_changed_dep,cc_lst_c)

# Compile assembler sources (.S)
# ---------------------------------------------------------------------------

modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)

$(real-obj-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
$(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)

# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
# or a file that it includes, in order to get versioned symbols. We build a
# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
#
# This is convoluted. The .S file must first be preprocessed to run guards and
# expand names, then the resulting exports must be constructed into plain
# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
# to make the genksyms input.
#
# These mirror gensymtypes_c and co above, keep them in synch.
cmd_gensymtypes_S =                                                         \
   { echo "\#include <linux/kernel.h>" ;                                    \
     echo "\#include <asm/asm-prototypes.h>" ;                              \
    $(CPP) $(a_flags) $< |                                                  \
     grep "\<___EXPORT_SYMBOL\>" |                                          \
     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
    $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
    scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
     $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
     $(if $(KBUILD_PRESERVE),-p)                                            \
     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))

quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
cmd_cc_symtypes_S =                                                         \
    $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
    test -s $@ || rm -f $@

$(obj)/%.symtypes : $(src)/%.S FORCE
	$(call cmd,cc_symtypes_S)


quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<

$(obj)/%.s: $(src)/%.S FORCE
	$(call if_changed_dep,cpp_s_S)

quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
      cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<

ifdef CONFIG_MODVERSIONS

ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)

ifneq ($(ASM_PROTOTYPES),)

# versioning matches the C process described above, with difference that
# we parse asm-prototypes.h C header to get function definitions.

cmd_modversions_S =								\
	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
		$(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
		    > $(@D)/.tmp_$(@F:.o=.ver);					\
										\
		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
			-T $(@D)/.tmp_$(@F:.o=.ver);				\
		mv -f $(@D)/.tmp_$(@F) $@;					\
		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
	fi
endif
endif

$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
	$(call if_changed_rule,as_o_S)

targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)
targets += $(extra-y) $(MAKECMDGOALS) $(always)

# Linker scripts preprocessor (.lds.S -> .lds)
# ---------------------------------------------------------------------------
quiet_cmd_cpp_lds_S = LDS     $@
      cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
	                     -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<

$(obj)/%.lds: $(src)/%.lds.S FORCE
	$(call if_changed_dep,cpp_lds_S)

# ASN.1 grammar
# ---------------------------------------------------------------------------
quiet_cmd_asn1_compiler = ASN.1   $@
      cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
				$(subst .h,.c,$@) $(subst .c,.h,$@)

$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
	$(call cmd,asn1_compiler)

# Build the compiled-in targets
# ---------------------------------------------------------------------------

# To build objects in subdirs, we need to descend into the directories
$(sort $(subdir-obj-y)): $(subdir-ym) ;

#
# Rule to compile a set of .o files into one .a file (without symbol table)
#
ifdef builtin-target

quiet_cmd_ar_builtin = AR      $@
      cmd_ar_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)

$(builtin-target): $(real-obj-y) FORCE
	$(call if_changed,ar_builtin)

targets += $(builtin-target)
endif # builtin-target

#
# Rule to create modules.order file
#
# Create commands to either record .ko file or cat modules.order from
# a subdirectory
modorder-cmds =						\
	$(foreach m, $(modorder),			\
		$(if $(filter %/modules.order, $m),	\
			cat $m;, echo kernel/$m;))

$(modorder-target): $(subdir-ym) FORCE
	$(Q)(cat /dev/null; $(modorder-cmds)) > $@

#
# Rule to compile a set of .o files into one .a file (with symbol table)
#
ifdef lib-target

$(lib-target): $(lib-y) FORCE
	$(call if_changed,ar)

targets += $(lib-target)

dummy-object = $(obj)/.lib_exports.o
ksyms-lds = $(dot-target).lds

quiet_cmd_export_list = EXPORTS $@
cmd_export_list = $(OBJDUMP) -h $< | \
	sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\
	rm -f $(dummy-object);\
	echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
	$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
	rm $(dummy-object) $(ksyms-lds)

$(obj)/lib-ksyms.o: $(lib-target) FORCE
	$(call if_changed,export_list)

targets += $(obj)/lib-ksyms.o

endif

# NOTE:
# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
# module is turned into a multi object module, $^ will contain header file
# dependencies recorded in the .*.cmd file.
quiet_cmd_link_multi-m = LD [M]  $@
cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^) $(cmd_secanalysis)

$(multi-used-m): FORCE
	$(call if_changed,link_multi-m)
	@{ echo $(@:.o=.ko); echo $(filter %.o,$^); \
	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
$(call multi_depend, $(multi-used-m), .o, -objs -y -m)

targets += $(multi-used-m)
targets := $(filter-out $(PHONY), $(targets))

# Add intermediate targets:
# When building objects with specific suffix patterns, add intermediate
# targets that the final targets are derived from.
intermediate_targets = $(foreach sfx, $(2), \
				$(patsubst %$(strip $(1)),%$(sfx), \
					$(filter %$(strip $(1)), $(targets))))
# %.asn1.o <- %.asn1.[ch] <- %.asn1
# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
# %.lex.o <- %.lex.c <- %.l
# %.tab.o <- %.tab.[ch] <- %.y
targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
	   $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
	   $(call intermediate_targets, .lex.o, .lex.c) \
	   $(call intermediate_targets, .tab.o, .tab.c .tab.h)

# Descending
# ---------------------------------------------------------------------------

PHONY += $(subdir-ym)
$(subdir-ym):
	$(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)

# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------

PHONY += FORCE

FORCE:

# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.

existing-targets := $(wildcard $(sort $(targets)))

-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)

ifneq ($(srctree),.)
# 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
endif

.PHONY: $(PHONY)