Commit 8b41fc44 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: create modules.builtin without Makefile.modbuiltin or tristate.conf 



Commit bc081dd6 ("kbuild: generate modules.builtin") added
infrastructure to generate modules.builtin, the list of all
builtin modules.

Basically, it works like this:

  - Kconfig generates include/config/tristate.conf, the list of
    tristate CONFIG options with a value in a capital letter.

  - scripts/Makefile.modbuiltin makes Kbuild descend into
    directories to collect the information of builtin modules.

I am not a big fan of it because Kbuild ends up with traversing
the source tree twice.

I am not sure how perfectly it should work, but this approach cannot
avoid false positives; even if the relevant CONFIG option is tristate,
some Makefiles forces obj-m to obj-y.

Some examples are:

  arch/powerpc/platforms/powermac/Makefile:
    obj-$(CONFIG_NVRAM:m=y)         += nvram.o

  net/ipv6/Makefile:
    obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o

  net/netlabel/Makefile:
    obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o

Nobody has complained about (or noticed) it, so it is probably fine to
have false positives in modules.builtin.

This commit simplifies the implementation. Let's exploit the fact
that every module has MODULE_LICENSE(). (modpost shows a warning if
MODULE_LICENSE is missing. If so, 0-day bot would already have blocked
such a module.)

I added MODULE_FILE to <linux/module.h>. When the code is being compiled
as builtin, it will be filled with the file path of the module, and
collected into modules.builtin.info. Then, scripts/link-vmlinux.sh
extracts the list of builtin modules out of it.

This new approach fixes the false-positives above, but adds another
type of false-positives; non-modular code may have MODULE_LICENSE()
by mistake. This is not a big deal, it is just the code is always
orphan. We can clean it up if we like. You can see cleanup examples by:

  $ git log --grep='make.* explicitly non-modular'

To sum up, this commits deletes lots of code, but still produces almost
equivalent results. Please note it does not increase the vmlinux size at
all. As you can see in include/asm-generic/vmlinux.lds.h, the .modinfo
section is discarded in the link stage.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent 1664a377

Documentation/kbuild/kconfig.rst

+0 −5
Original line number Diff line number Diff line
@@ -154,11 +154,6 @@ KCONFIG_AUTOCONFIG 
This environment variable can be set to specify the path & name of the

"auto.conf" file.  Its default value is "include/config/auto.conf".



KCONFIG_TRISTATE

----------------

This environment variable can be set to specify the path & name of the

"tristate.conf" file.  Its default value is "include/config/tristate.conf".



KCONFIG_AUTOHEADER

------------------

This environment variable can be set to specify the path & name of the

Makefile

+5 −16
Original line number Diff line number Diff line
@@ -674,7 +674,7 @@ $(KCONFIG_CONFIG): 
#

# This exploits the 'multi-target pattern rule' trick.

# The syncconfig should be executed only once to make all the targets.

%/auto.conf %/auto.conf.cmd %/tristate.conf: $(KCONFIG_CONFIG)

%/auto.conf %/auto.conf.cmd: $(KCONFIG_CONFIG)

	$(Q)$(MAKE) -f $(srctree)/Makefile syncconfig

else # !may-sync-config

# External modules and some install targets need include/generated/autoconf.h
@@ -1278,24 +1278,13 @@ all: modules 
# using awk while concatenating to the final file.



PHONY += modules

modules: $(if $(KBUILD_BUILTIN),vmlinux) modules.order modules.builtin

modules: $(if $(KBUILD_BUILTIN),vmlinux) modules.order

	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh



modules.order: descend

	$(Q)$(AWK) '!x[$$0]++' $(addsuffix /$@, $(build-dirs)) > $@



modbuiltin-dirs := $(addprefix _modbuiltin_, $(build-dirs))



modules.builtin: $(modbuiltin-dirs)

	$(Q)$(AWK) '!x[$$0]++' $(addsuffix /$@, $(build-dirs)) > $@



PHONY += $(modbuiltin-dirs)

# tristate.conf is not included from this Makefile. Add it as a prerequisite

# here to make it self-healing in case somebody accidentally removes it.

$(modbuiltin-dirs): include/config/tristate.conf

	$(Q)$(MAKE) $(modbuiltin)=$(patsubst _modbuiltin_%,%,$@)



# Target to prepare building external modules

PHONY += modules_prepare

modules_prepare: prepare
@@ -1315,7 +1304,7 @@ _modinst_: 
		ln -s $(CURDIR) $(MODLIB)/build ; \

	fi

	@sed 's:^:kernel/:' modules.order > $(MODLIB)/modules.order

	@sed 's:^:kernel/:' modules.builtin > $(MODLIB)/modules.builtin

	@cp -f modules.builtin $(MODLIB)/

	@cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/

	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
@@ -1357,7 +1346,7 @@ endif # CONFIG_MODULES 


# Directories & files removed with 'make clean'

CLEAN_DIRS  += include/ksym

CLEAN_FILES += modules.builtin.modinfo modules.nsdeps

CLEAN_FILES += modules.builtin modules.builtin.modinfo modules.nsdeps



# Directories & files removed with 'make mrproper'

MRPROPER_DIRS  += include/config include/generated          \
@@ -1712,7 +1701,7 @@ clean: $(clean-dirs) 
		-o -name '*.lex.c' -o -name '*.tab.[ch]' \

		-o -name '*.asn1.[ch]' \

		-o -name '*.symtypes' -o -name 'modules.order' \

		-o -name modules.builtin -o -name '.tmp_*.o.*' \

		-o -name '.tmp_*.o.*' \

		-o -name '*.c.[012]*.*' \

		-o -name '*.ll' \

		-o -name '*.gcno' \) -type f -print | xargs rm -f

include/linux/module.h

+11 −1
Original line number Diff line number Diff line
@@ -169,6 +169,16 @@ extern void cleanup_module(void); 
 */

#define MODULE_SOFTDEP(_softdep) MODULE_INFO(softdep, _softdep)



/*

 * MODULE_FILE is used for generating modules.builtin

 * So, make it no-op when this is being built as a module

 */

#ifdef MODULE

#define MODULE_FILE

#else

#define MODULE_FILE	MODULE_INFO(file, KBUILD_MODFILE);

#endif



/*

 * The following license idents are currently accepted as indicating free

 * software modules
@@ -213,7 +223,7 @@ extern void cleanup_module(void); 
 * 2.	So the community can ignore bug reports including proprietary modules

 * 3.	So vendors can do likewise based on their own policies

 */

#define MODULE_LICENSE(_license) MODULE_INFO(license, _license)

#define MODULE_LICENSE(_license) MODULE_FILE MODULE_INFO(license, _license)



/*

 * Author(s), use "Name <email>" or just "Name", for multiple

scripts/Kbuild.include

+0 −6
Original line number Diff line number Diff line
@@ -163,12 +163,6 @@ ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4)) 
# $(Q)$(MAKE) $(build)=dir

build := -f $(srctree)/scripts/Makefile.build obj



###

# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=

# Usage:

# $(Q)$(MAKE) $(modbuiltin)=dir

modbuiltin := -f $(srctree)/scripts/Makefile.modbuiltin obj



###

# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj=

# Usage:

scripts/Makefile.modbuiltin

deleted100644 → 0
+0 −57
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

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

# Generating modules.builtin

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



src := $(obj)



PHONY := __modbuiltin

__modbuiltin:



include include/config/auto.conf

# tristate.conf sets tristate variables to uppercase 'Y' or 'M'

# That way, we get the list of built-in modules in obj-Y

include include/config/tristate.conf



include scripts/Kbuild.include



ifdef building_out_of_srctree

# Create output directory if not already present

_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))

endif



# 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

__subdir-Y     := $(patsubst %/,%,$(filter %/, $(obj-Y)))

subdir-Y       += $(__subdir-Y)

subdir-ym      := $(sort $(subdir-y) $(subdir-Y) $(subdir-m))

subdir-ym      := $(addprefix $(obj)/,$(subdir-ym))

obj-Y          := $(addprefix $(obj)/,$(obj-Y))



modbuiltin-subdirs := $(patsubst %,%/modules.builtin, $(subdir-ym))

modbuiltin-mods    := $(filter %.ko, $(obj-Y:.o=.ko))

modbuiltin-target  := $(obj)/modules.builtin



__modbuiltin: $(modbuiltin-target) $(subdir-ym)

	@:



$(modbuiltin-target): $(subdir-ym) FORCE

	$(Q)(for m in $(modbuiltin-mods); do echo $$m; done;	\

	cat /dev/null $(modbuiltin-subdirs)) > $@



PHONY += FORCE



FORCE:



# Descending

# ---------------------------------------------------------------------------



PHONY += $(subdir-ym)

$(subdir-ym):

	$(Q)$(MAKE) $(modbuiltin)=$@



.PHONY: $(PHONY)

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