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Makefile.modpost
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Makefile.modpost
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# 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' -exec grep -h '\.ko$$' {} \; | sort -u
__modules := $(shell $(MODLISTCMD))
modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
# Step 2), invoke modpost
# Includes step 3,4
modpost = scripts/mod/modpost \
$(if $(CONFIG_MODVERSIONS),-m) \
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,) \
$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
$(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
$(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S) \
$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
$(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
# If CONFIG_LTO_CLANG is enabled, .o files are either LLVM IR, or empty, so we
# need to link them into actual objects before passing them to modpost
modpost-ext = $(if $(CONFIG_LTO_CLANG),.lto,)
ifdef CONFIG_LTO_CLANG
quiet_cmd_cc_lto_link_modules = LD [M] $@
cmd_cc_lto_link_modules = \
$(LD) $(ld_flags) -r -o $(@) \
$(shell [ -s $(@:$(modpost-ext).o=.o.symversions) ] && \
echo -T $(@:$(modpost-ext).o=.o.symversions)) \
--whole-archive $(filter-out FORCE,$^)
$(modules:.ko=$(modpost-ext).o): %$(modpost-ext).o: %.o FORCE
$(call if_changed,cc_lto_link_modules)
endif
# We can go over command line length here, so be careful.
quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/$(modpost-ext)\.o/' | $(modpost) $(MODPOST_OPT) -s -T -
PHONY += __modpost
__modpost: $(modules:.ko=$(modpost-ext).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] $@
ifdef CONFIG_LTO_CLANG
cmd_ld_ko_o = \
$(LD) -r $(LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
$(shell [ -s $(@:.ko=.o.symversions) ] && \
echo -T $(@:.ko=.o.symversions)) \
-o $@ --whole-archive \
$(filter-out FORCE,$(^:$(modpost-ext).o=.o))
ifdef CONFIG_FTRACE_MCOUNT_RECORD
cmd_ld_ko_o += ; $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) $@
endif
else
cmd_ld_ko_o = \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-o $@ $(filter-out FORCE,$^) ; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
endif
$(modules): %.ko: %$(modpost-ext).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)