Merge tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - allow users to invoke 'make' out of the source tree

 - refactor scripts/mkmakefile

 - deprecate KBUILD_SRC, which was used to track the source tree
   location for O= build.

 - fix recordmcount.pl in case objdump output is localized

 - turn unresolved symbols in external modules to errors from warnings
   by default; pass KBUILD_MODPOST_WARN=1 to get them back to warnings

 - generate modules.builtin.modinfo to collect .modinfo data from
   built-in modules

 - misc Makefile cleanups

* tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (21 commits)
  .gitignore: add more all*.config patterns
  moduleparam: Save information about built-in modules in separate file
  Remove MODULE_ALIAS() calls that take undefined macro
  .gitignore: add leading and trailing slashes to generated directories
  scripts/tags.sh: fix direct execution of scripts/tags.sh
  scripts: override locale from environment when running recordmcount.pl
  samples: kobject: allow CONFIG_SAMPLE_KOBJECT to become y
  samples: seccomp: turn CONFIG_SAMPLE_SECCOMP into a bool option
  kbuild: move Documentation to vmlinux-alldirs
  kbuild: move samples/ to KBUILD_VMLINUX_OBJS
  modpost: make KBUILD_MODPOST_WARN also configurable for external modules
  kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build
  kbuild: remove unneeded dependency for include/config/kernel.release
  memory: squash drivers/memory/Makefile.asm-offsets
  kbuild: use $(srctree) instead of KBUILD_SRC to check out-of-tree build
  kbuild: mkmakefile: generate a simple wrapper of top Makefile
  kbuild: mkmakefile: do not check the generated Makefile marker
  kbuild: allow Kbuild to start from any directory
  kbuild: pass $(MAKECMDGOALS) to sub-make as is
  kbuild: fix warning "overriding recipe for target 'Makefile'"
  ...

1 files changed, 81 insertions, 65 deletions

diff --git a/Makefile b/Makefile
index bcf2e7628fe5..a61a95b6b38f 100644
--- a/Makefile
+++ b/Makefile
@@ -96,56 +96,65 @@ endif
 
 export quiet Q KBUILD_VERBOSE
 
-# kbuild supports saving output files in a separate directory.
-# To locate output files in a separate directory two syntaxes are supported.
-# In both cases the working directory must be the root of the kernel src.
+# Kbuild will save output files in the current working directory.
+# This does not need to match to the root of the kernel source tree.
+#
+# For example, you can do this:
+#
+#  cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
+#
+# If you want to save output files in a different location, there are
+# two syntaxes to specify it.
+#
 # 1) O=
 # Use "make O=dir/to/store/output/files/"
 #
 # 2) Set KBUILD_OUTPUT
-# Set the environment variable KBUILD_OUTPUT to point to the directory
-# where the output files shall be placed.
-# export KBUILD_OUTPUT=dir/to/store/output/files/
-# make
+# Set the environment variable KBUILD_OUTPUT to point to the output directory.
+# export KBUILD_OUTPUT=dir/to/store/output/files/; make
 #
 # The O= assignment takes precedence over the KBUILD_OUTPUT environment
 # variable.
 
-# KBUILD_SRC is not intended to be used by the regular user (for now),
-# it is set on invocation of make with KBUILD_OUTPUT or O= specified.
-
-# OK, Make called in directory where kernel src resides
-# Do we want to locate output files in a separate directory?
+# Do we want to change the working directory?
 ifeq ("$(origin O)", "command line")
   KBUILD_OUTPUT := $(O)
 endif
 
-ifneq ($(words $(subst :, ,$(CURDIR))), 1)
-  $(error main directory cannot contain spaces nor colons)
+ifneq ($(KBUILD_OUTPUT),)
+# Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
+# expand a shell special character '~'. We use a somewhat tedious way here.
+abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
+$(if $(abs_objtree),, \
+     $(error failed to create output directory "$(KBUILD_OUTPUT)"))
+
+# $(realpath ...) resolves symlinks
+abs_objtree := $(realpath $(abs_objtree))
+else
+abs_objtree := $(CURDIR)
+endif # ifneq ($(KBUILD_OUTPUT),)
+
+ifeq ($(abs_objtree),$(CURDIR))
+# Suppress "Entering directory ..." unless we are changing the work directory.
+MAKEFLAGS += --no-print-directory
+else
+need-sub-make := 1
 endif
 
-ifneq ($(KBUILD_OUTPUT),)
-# check that the output directory actually exists
-saved-output := $(KBUILD_OUTPUT)
-KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
-								&& pwd)
-$(if $(KBUILD_OUTPUT),, \
-     $(error failed to create output directory "$(saved-output)"))
+abs_srctree := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
 
+ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
+$(error source directory cannot contain spaces or colons)
+endif
+
+ifneq ($(abs_srctree),$(abs_objtree))
 # Look for make include files relative to root of kernel src
 #
 # This does not become effective immediately because MAKEFLAGS is re-parsed
-# once after the Makefile is read.  It is OK since we are going to invoke
-# 'sub-make' below.
-MAKEFLAGS += --include-dir=$(CURDIR)
-
+# once after the Makefile is read. We need to invoke sub-make.
+MAKEFLAGS += --include-dir=$(abs_srctree)
 need-sub-make := 1
-else
-
-# Do not print "Entering directory ..." at all for in-tree build.
-MAKEFLAGS += --no-print-directory
-
-endif # ifneq ($(KBUILD_OUTPUT),)
+endif
 
 ifneq ($(filter 3.%,$(MAKE_VERSION)),)
 # 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
@@ -155,20 +164,19 @@ need-sub-make := 1
 $(lastword $(MAKEFILE_LIST)): ;
 endif
 
+export abs_srctree abs_objtree
 export sub_make_done := 1
 
 ifeq ($(need-sub-make),1)
 
 PHONY += $(MAKECMDGOALS) sub-make
 
-$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
+$(filter-out _all sub-make $(lastword $(MAKEFILE_LIST)), $(MAKECMDGOALS)) _all: sub-make
 	@:
 
 # Invoke a second make in the output directory, passing relevant variables
 sub-make:
-	$(Q)$(MAKE) \
-	$(if $(KBUILD_OUTPUT),-C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR)) \
-	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
+	$(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
 
 endif # need-sub-make
 endif # sub_make_done
@@ -213,16 +221,21 @@ ifeq ("$(origin M)", "command line")
   KBUILD_EXTMOD := $(M)
 endif
 
-ifeq ($(KBUILD_SRC),)
+ifeq ($(abs_srctree),$(abs_objtree))
         # building in the source tree
         srctree := .
 else
-        ifeq ($(KBUILD_SRC)/,$(dir $(CURDIR)))
+        ifeq ($(abs_srctree)/,$(dir $(abs_objtree)))
                 # building in a subdirectory of the source tree
                 srctree := ..
         else
-                srctree := $(KBUILD_SRC)
+                srctree := $(abs_srctree)
         endif
+
+	# TODO:
+	# KBUILD_SRC is only used to distinguish in-tree/out-of-tree build.
+	# Replace it with $(srctree) or something.
+	KBUILD_SRC := $(abs_srctree)
 endif
 
 export KBUILD_CHECKSRC KBUILD_EXTMOD KBUILD_SRC
@@ -436,7 +449,7 @@ USERINCLUDE    := \
 LINUXINCLUDE    := \
 		-I$(srctree)/arch/$(SRCARCH)/include \
 		-I$(objtree)/arch/$(SRCARCH)/include/generated \
-		$(if $(KBUILD_SRC), -I$(srctree)/include) \
+		$(if $(filter .,$(srctree)),,-I$(srctree)/include) \
 		-I$(objtree)/include \
 		$(USERINCLUDE)
 
@@ -497,7 +510,7 @@ PHONY += outputmakefile
 # At the same time when output Makefile generated, generate .gitignore to
 # ignore whole output directory
 outputmakefile:
-ifneq ($(KBUILD_SRC),)
+ifneq ($(srctree),.)
 	$(Q)ln -fsn $(srctree) source
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
 	$(Q)test -e .gitignore || \
@@ -520,15 +533,6 @@ KBUILD_AFLAGS	+= $(CLANG_FLAGS)
 export CLANG_FLAGS
 endif
 
-RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
-RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register
-RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
-RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
-RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
-RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
-export RETPOLINE_CFLAGS
-export RETPOLINE_VDSO_CFLAGS
-
 # The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
 # Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
 # CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
@@ -595,20 +599,21 @@ endif
 
 export KBUILD_MODULES KBUILD_BUILTIN
 
+ifeq ($(dot-config),1)
+include include/config/auto.conf
+endif
+
 ifeq ($(KBUILD_EXTMOD),)
 # Objects we will link into vmlinux / subdirs we need to visit
 init-y		:= init/
 drivers-y	:= drivers/ sound/
+drivers-$(CONFIG_SAMPLES) += samples/
 net-y		:= net/
 libs-y		:= lib/
 core-y		:= usr/
 virt-y		:= virt/
 endif # KBUILD_EXTMOD
 
-ifeq ($(dot-config),1)
-include include/config/auto.conf
-endif
-
 # The all: target is the default when no target is given on the
 # command line.
 # This allow a user to issue only 'make' to build a kernel including modules
@@ -625,6 +630,15 @@ ifdef CONFIG_FUNCTION_TRACER
   CC_FLAGS_FTRACE := -pg
 endif
 
+RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
+RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register
+RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
+RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
+RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
+RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
+export RETPOLINE_CFLAGS
+export RETPOLINE_VDSO_CFLAGS
+
 # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
 # values of the respective KBUILD_* variables
 ARCH_CPPFLAGS :=
@@ -985,8 +999,9 @@ vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
 		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
 		     $(net-y) $(net-m) $(libs-y) $(libs-m) $(virt-y)))
 
-vmlinux-alldirs	:= $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
-		     $(init-) $(core-) $(drivers-) $(net-) $(libs-) $(virt-))))
+vmlinux-alldirs	:= $(sort $(vmlinux-dirs) Documentation \
+		     $(patsubst %/,%,$(filter %/, $(init-) $(core-) \
+			$(drivers-) $(net-) $(libs-) $(virt-))))
 
 init-y		:= $(patsubst %/, %/built-in.a, $(init-y))
 core-y		:= $(patsubst %/, %/built-in.a, $(core-y))
@@ -1003,7 +1018,7 @@ export KBUILD_VMLINUX_LIBS := $(libs-y1)
 export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
 export LDFLAGS_vmlinux
 # used by scripts/package/Makefile
-export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
+export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch include scripts tools)
 
 vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
 
@@ -1040,11 +1055,8 @@ vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
 
 targets := vmlinux
 
-# Build samples along the rest of the kernel. This needs headers_install.
-ifdef CONFIG_SAMPLES
-vmlinux-dirs += samples
+# Some samples need headers_install.
 samples: headers_install
-endif
 
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
@@ -1064,7 +1076,7 @@ filechk_kernel.release = \
 	echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
 
 # Store (new) KERNELRELEASE string in include/config/kernel.release
-include/config/kernel.release: $(srctree)/Makefile FORCE
+include/config/kernel.release: FORCE
 	$(call filechk,kernel.release)
 
 # Additional helpers built in scripts/
@@ -1086,9 +1098,11 @@ PHONY += prepare archprepare prepare1 prepare3
 # and if so do:
 # 1) Check that make has not been executed in the kernel src $(srctree)
 prepare3: include/config/kernel.release
-ifneq ($(KBUILD_SRC),)
+ifneq ($(srctree),.)
 	@$(kecho) '  Using $(srctree) as source for kernel'
-	$(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
+	$(Q)if [ -f $(srctree)/.config -o \
+		 -d $(srctree)/include/config -o \
+		 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
 		echo >&2 "  $(srctree) is not clean, please run 'make mrproper'"; \
 		echo >&2 "  in the '$(srctree)' directory.";\
 		/bin/false; \
@@ -1304,6 +1318,7 @@ _modinst_:
 	fi
 	@cp -f $(objtree)/modules.order $(MODLIB)/
 	@cp -f $(objtree)/modules.builtin $(MODLIB)/
+	@cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
 
 # This depmod is only for convenience to give the initial
@@ -1344,10 +1359,11 @@ endif # CONFIG_MODULES
 
 # Directories & files removed with 'make clean'
 CLEAN_DIRS  += $(MODVERDIR) include/ksym
+CLEAN_FILES += modules.builtin.modinfo
 
 # Directories & files removed with 'make mrproper'
 MRPROPER_DIRS  += include/config usr/include include/generated          \
-		  arch/*/include/generated .tmp_objdiff
+		  arch/$(SRCARCH)/include/generated .tmp_objdiff
 MRPROPER_FILES += .config .config.old .version \
 		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS \
 		  signing_key.pem signing_key.priv signing_key.x509	\
@@ -1358,7 +1374,7 @@ MRPROPER_FILES += .config .config.old .version \
 #
 clean: rm-dirs  := $(CLEAN_DIRS)
 clean: rm-files := $(CLEAN_FILES)
-clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs) Documentation samples)
+clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs))
 
 PHONY += $(clean-dirs) clean archclean vmlinuxclean
 $(clean-dirs):