Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - add modpost warn exported symbols marked as 'static' because 'static'
   and EXPORT_SYMBOL is an odd combination

 - break the build early if gold linker is used

 - optimize the Bison rule to produce .c and .h files by a single
   pattern rule

 - handle PREEMPT_RT in the module vermagic and UTS_VERSION

 - warn CONFIG options leaked to the user-space except existing ones

 - make single targets work properly

 - rebuild modules when module linker scripts are updated

 - split the module final link stage into scripts/Makefile.modfinal

 - fix the missed error code in merge_config.sh

 - improve the error message displayed on the attempt of the O= build in
   unclean source tree

 - remove 'clean-dirs' syntax

 - disable -Wimplicit-fallthrough warning for Clang

 - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC

 - remove ARCH_{CPP,A,C}FLAGS variables

 - add $(BASH) to run bash scripts

 - change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
   instead of the basename

 - stop suppressing Clang's -Wunused-function warnings when W=1

 - fix linux/export.h to avoid genksyms calculating CRC of trimmed
   exported symbols

 - misc cleanups

* tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits)
  genksyms: convert to SPDX License Identifier for lex.l and parse.y
  modpost: use __section in the output to *.mod.c
  modpost: use MODULE_INFO() for __module_depends
  export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
  export.h: remove defined(__KERNEL__), which is no longer needed
  kbuild: allow Clang to find unused static inline functions for W=1 build
  kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN
  kbuild: refactor scripts/Makefile.extrawarn
  merge_config.sh: ignore unwanted grep errors
  kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)
  modpost: add NOFAIL to strndup
  modpost: add guid_t type definition
  kbuild: add $(BASH) to run scripts with bash-extension
  kbuild: remove ARCH_{CPP,A,C}FLAGS
  kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
  kbuild: Do not enable -Wimplicit-fallthrough for clang for now
  kbuild: clean up subdir-ymn calculation in Makefile.clean
  kbuild: remove unneeded '+' marker from cmd_clean
  kbuild: remove clean-dirs syntax
  kbuild: check clean srctree even earlier
  ...

1 files changed, 60 insertions, 0 deletions

diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
new file mode 100644
index 000000000000..411c1e600e7d
--- /dev/null
+++ b/scripts/Makefile.modfinal
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# ===========================================================================
+# Module final link
+# ===========================================================================
+
+PHONY := __modfinal
+__modfinal:
+
+include $(srctree)/scripts/Kbuild.include
+
+# for c_flags
+include $(srctree)/scripts/Makefile.lib
+
+# find all modules listed in modules.order
+modules := $(sort $(shell cat $(MODORDER)))
+
+__modfinal: $(modules)
+	@:
+
+# modname and part-of-module are set to make c_flags define proper module flags
+modname = $(notdir $(@:.mod.o=))
+part-of-module = y
+
+quiet_cmd_cc_o_c = CC [M]  $@
+      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
+
+%.mod.o: %.mod.c FORCE
+	$(call if_changed_dep,cc_o_c)
+
+ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
+
+quiet_cmd_ld_ko_o = LD [M]  $@
+      cmd_ld_ko_o =                                                     \
+	$(LD) -r $(KBUILD_LDFLAGS)					\
+		$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)		\
+		$(addprefix -T , $(KBUILD_LDS_MODULE))			\
+		-o $@ $(filter %.o, $^);				\
+	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
+
+$(modules): %.ko: %.o %.mod.o $(KBUILD_LDS_MODULE) FORCE
+	+$(call if_changed,ld_ko_o)
+
+targets += $(modules) $(modules:.ko=.mod.o)
+
+# 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.
+
+existing-targets := $(wildcard $(sort $(targets)))
+
+-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
+
+.PHONY: $(PHONY)