linux-next/scripts/Makefile.modfinal
Thomas Weißschuh fdf94e4403 kbuild: compile constant module information only once
Various information about modules is compiled into the info sections.
For that a dedicated .mod.c file is generated by modpost for each module
and then linked into the module.
However most of the information in the .mod.c is the same for all
modules, internal and external.
Split the shared information into a dedicated source file that is
compiled once and then linked into all modules.

This avoids frequent rebuilds for all .mod.c files when using
CONFIG_LOCALVERSION_AUTO because the local version ends up in .mod.c
through UTS_RELEASE and VERMAGIC_STRING.
The modules are still relinked in this case.

The code is also easier to maintain as it's now in a proper source file
instead of an inline string literal.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-09-07 17:24:08 +09:00

84 lines
2.8 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0-only
# ===========================================================================
# Module final link
# ===========================================================================
PHONY := __modfinal
__modfinal:
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
# for c_flags
include $(srctree)/scripts/Makefile.lib
# find all modules listed in modules.order
modules := $(call read-file, $(MODORDER))
__modfinal: $(modules:%.o=%.ko)
@:
# modname and part-of-module are set to make c_flags define proper module flags
modname = $(notdir $(@:.mod.o=))
part-of-module = y
GCOV_PROFILE := n
KCSAN_SANITIZE := n
quiet_cmd_cc_o_c = CC [M] $@
cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI), $(c_flags)) -c -o $@ $<
%.mod.o: %.mod.c FORCE
$(call if_changed_dep,cc_o_c)
$(extmod_prefix).module-common.o: $(srctree)/scripts/module-common.c FORCE
$(call if_changed_dep,cc_o_c)
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o += \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-T scripts/module.lds -o $@ $(filter %.o, $^)
quiet_cmd_btf_ko = BTF [M] $@
cmd_btf_ko = \
if [ ! -f vmlinux ]; then \
printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
else \
LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base vmlinux $@; \
$(RESOLVE_BTFIDS) -b vmlinux $@; \
fi;
# Same as newer-prereqs, but allows to exclude specified extra dependencies
newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
# Same as if_changed, but allows to exclude specified extra dependencies
if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
$(cmd); \
printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
# Re-generate module BTFs if either module's .ko or vmlinux changed
%.ko: %.o %.mod.o $(extmod_prefix).module-common.o scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),vmlinux) FORCE
+$(call if_changed_except,ld_ko_o,vmlinux)
ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+$(if $(newer-prereqs),$(call cmd,btf_ko))
endif
targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o) $(extmod_prefix).module-common.o
# Add FORCE to the prerequisites 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)
.PHONY: $(PHONY)