kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod

Towards the goal of removing MODVERDIR, read out modules.order to get
the list of modules to be processed. This is simpler than parsing *.mod
files in $(MODVERDIR).

For external modules, $(KBUILD_EXTMOD)/modules.order should be read.

I removed the single target %.ko from the top Makefile. To make sure
modpost works correctly, vmlinux and the other modules must be built.
You cannot build a particular .ko file alone.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1772,8 +1772,6 @@ build-dir = $(patsubst %/,%,$(dir $(build-target)))
 	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
 %.symtypes: prepare FORCE
 	$(Q)$(MAKE) $(build)=$(build-dir) $(build-target)
-%.ko: %.o
-	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
 # Modules
 PHONY += /

scripts/Makefile.modpost

@@ -8,9 +8,10 @@
 # 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
+# d) modules.order, which lists all the modules
 
 # Stage 2 is handled by this file and does the following
-# 1) Find all modules from the files listed in $(MODVERDIR)/
+# 1) Find all modules listed in modules.order
 # 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
@@ -60,10 +61,12 @@ 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)))
+modorder := $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)modules.order
+
+# Step 1), find all modules listed in modules.order
+ifdef CONFIG_MODULES
+modules := $(sort $(shell cat $(modorder)))
+endif
 
 # Stop after building .o files if NOFINAL is set. Makes compile tests quicker
 _modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
@@ -84,7 +87,7 @@ 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$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -
+      cmd_modpost = sed 's/ko$$/o/' $(modorder) | $(modpost) $(MODPOST_OPT) -s -T -
 
 PHONY += __modpost
 __modpost: $(modules:.ko=.o) FORCE