# SPDX-License-Identifier: GPL-2.0

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

# Module versions

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

#

# Stage one of module building created the following:

# a) The individual .o files used for the module

# b) A <module>.o file which is the .o files above linked together

# c) A <module>.mod file in $(MODVERDIR)/, listing the name of the

# the preliminary <module>.o file, plus all .o files

# Stage 2 is handled by this file and does the following

# 1) Find all modules from the files listed in $(MODVERDIR)/

# 2) modpost is then used to

# 3) create one <module>.mod.c file pr. module

# 4) create one Module.symvers file with CRC for all exported symbols

# 5) compile all <module>.mod.c files

# 6) final link of the module to a <module.ko> file

# Step 3 is used to place certain information in the module's ELF

# section, including information such as:

# Version magic (see include/linux/vermagic.h for full details)

# - Kernel release

# - SMP is CONFIG_SMP

# - PREEMPT is CONFIG_PREEMPT

# - GCC Version

# Module info

# - Module version (MODULE_VERSION)

# - Module alias'es (MODULE_ALIAS)

# - Module license (MODULE_LICENSE)

# - See include/linux/module.h for more details

# Step 4 is solely used to allow module versioning in external modules,

# where the CRC of each module is retrieved from the Module.symvers file.

# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined

# symbols in the final module linking stage

# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.

# This is solely useful to speed up test compiles

PHONY := _modpost

_modpost: __modpost

include include/config/auto.conf

include scripts/Kbuild.include

# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info

ifneq ($(KBUILD_EXTMOD),)

# set src + obj - they may be used when building the .mod.c file

obj := $(KBUILD_EXTMOD)

src := $(obj)

# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS

include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \

$(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)

endif

include scripts/Makefile.lib

kernelsymfile := $(objtree)/Module.symvers

modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers

# Step 1), find all modules listed in $(MODVERDIR)/

MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u

__modules := $(shell $(MODLISTCMD))

modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))

# Stop after building .o files if NOFINAL is set. Makes compile tests quicker

_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))

# Step 2), invoke modpost

# Includes step 3,4

modpost = scripts/mod/modpost \

$(if $(CONFIG_MODVERSIONS),-m) \

$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,) \

$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \

$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \

$(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \

$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \

$(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S) \

$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \

$(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)

MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))

# We can go over command line length here, so be careful.

quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules

cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -

PHONY += __modpost

__modpost: $(modules:.ko=.o) FORCE

$(call cmd,modpost) $(wildcard vmlinux)

quiet_cmd_kernel-mod = MODPOST $@

cmd_kernel-mod = $(modpost) $@

vmlinux.o: FORCE

$(call cmd,kernel-mod)

# Declare generated files as targets for modpost

$(modules:.ko=.mod.c): __modpost ;

# Step 5), compile all *.mod.c files

# modname is set to make c_flags define KBUILD_MODNAME

modname = $(notdir $(@:.mod.o=))

quiet_cmd_cc_o_c = CC $@

cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \

-c -o $@ $<

$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE

$(call if_changed_dep,cc_o_c)

targets += $(modules:.ko=.mod.o)

ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)

# Step 6), final link of the modules with optional arch pass after final link

quiet_cmd_ld_ko_o = LD [M] $@

cmd_ld_ko_o = \

$(LD) -r $(LDFLAGS) \

$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \

-o $@ $(filter-out FORCE,$^) ; \

$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)

$(modules): %.ko :%.o %.mod.o FORCE

+$(call if_changed,ld_ko_o)

targets += $(modules)

# 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.

cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)

include $(cmd_files)

endif

.PHONY: $(PHONY)