Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild

Pull kbuild updates from Michal Marek:

 - new option CONFIG_TRIM_UNUSED_KSYMS which does a two-pass build and
   unexports symbols which are not used in the current config [Nicolas
   Pitre]

 - several kbuild rule cleanups [Masahiro Yamada]

 - warning option adjustments for gcov etc [Arnd Bergmann]

 - a few more small fixes

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (31 commits)
  kbuild: move -Wunused-const-variable to W=1 warning level
  kbuild: fix if_change and friends to consider argument order
  kbuild: fix adjust_autoksyms.sh for modules that need only one symbol
  kbuild: fix ksym_dep_filter when multiple EXPORT_SYMBOL() on the same line
  gcov: disable -Wmaybe-uninitialized warning
  gcov: disable tree-loop-im to reduce stack usage
  gcov: disable for COMPILE_TEST
  Kbuild: disable 'maybe-uninitialized' warning for CONFIG_PROFILE_ALL_BRANCHES
  Kbuild: change CC_OPTIMIZE_FOR_SIZE definition
  kbuild: forbid kernel directory to contain spaces and colons
  kbuild: adjust ksym_dep_filter for some cmd_* renames
  kbuild: Fix dependencies for final vmlinux link
  kbuild: better abstract vmlinux sequential prerequisites
  kbuild: fix call to adjust_autoksyms.sh when output directory specified
  kbuild: Get rid of KBUILD_STR
  kbuild: rename cmd_as_s_S to cmd_cpp_s_S
  kbuild: rename cmd_cc_i_c to cmd_cpp_i_c
  kbuild: drop redundant "PHONY += FORCE"
  kbuild: delete unnecessary "@:"
  kbuild: mark help target as PHONY
  ...

Makefile

@@ -128,6 +128,10 @@ _all:
 # Cancel implicit rules on top Makefile
 $(CURDIR)/Makefile Makefile: ;
 
+ifneq ($(words $(subst :, ,$(CURDIR))), 1)
+  $(error main directory cannot contain spaces nor colons)
+endif
+
 ifneq ($(KBUILD_OUTPUT),)
 # Invoke a second make in the output directory, passing relevant variables
 # check that the output directory actually exists
@@ -142,7 +146,7 @@ PHONY += $(MAKECMDGOALS) sub-make
 $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
 	@:
 
-sub-make: FORCE
+sub-make:
 	$(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \
 	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
 
@@ -364,7 +368,7 @@ AFLAGS_MODULE   =
 LDFLAGS_MODULE  =
 CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
-CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage
+CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
 CFLAGS_KCOV	= -fsanitize-coverage=trace-pc
 
 
@@ -617,7 +621,11 @@ KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 KBUILD_CFLAGS	+= -Os $(call cc-disable-warning,maybe-uninitialized,)
 else
-KBUILD_CFLAGS	+= -O2
+ifdef CONFIG_PROFILE_ALL_BRANCHES
+KBUILD_CFLAGS	+= -O2 $(call cc-disable-warning,maybe-uninitialized,)
+else
+KBUILD_CFLAGS   += -O2
+endif
 endif
 
 # Tell gcc to never replace conditional load with a non-conditional one
@@ -697,9 +705,10 @@ KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
 else
 
-# This warning generated too much noise in a regular build.
-# Use make W=1 to enable this warning (see scripts/Makefile.build)
+# These warnings generated too much noise in a regular build.
+# Use make W=1 to enable them (see scripts/Makefile.build)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 endif
 
 ifdef CONFIG_FRAME_POINTER
@@ -926,27 +935,41 @@ export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Doc
 
 vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)
 
-# Final link of vmlinux
-      cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
-quiet_cmd_link-vmlinux = LINK    $@
-
-# Include targets which we want to
-# execute if the rest of the kernel build went well.
-vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE
+# Include targets which we want to execute sequentially if the rest of the
+# kernel build went well. If CONFIG_TRIM_UNUSED_KSYMS is set, this might be
+# evaluated more than once.
+PHONY += vmlinux_prereq
+vmlinux_prereq: $(vmlinux-deps) FORCE
 ifdef CONFIG_HEADERS_CHECK
 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
-ifdef CONFIG_SAMPLES
-	$(Q)$(MAKE) $(build)=samples
-endif
 ifdef CONFIG_BUILD_DOCSRC
 	$(Q)$(MAKE) $(build)=Documentation
 endif
 ifdef CONFIG_GDB_SCRIPTS
 	$(Q)ln -fsn `cd $(srctree) && /bin/pwd`/scripts/gdb/vmlinux-gdb.py
 endif
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
+	  "$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile vmlinux_prereq"
+endif
+
+# standalone target for easier testing
+include/generated/autoksyms.h: FORCE
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh true
+
+# Final link of vmlinux
+      cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
+quiet_cmd_link-vmlinux = LINK    $@
+
+vmlinux: scripts/link-vmlinux.sh vmlinux_prereq $(vmlinux-deps) FORCE
 	+$(call if_changed,link-vmlinux)
 
+# Build samples along the rest of the kernel
+ifdef CONFIG_SAMPLES
+vmlinux-dirs += samples
+endif
+
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
 $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
@@ -998,10 +1021,12 @@ prepare2: prepare3 outputmakefile asm-generic
 prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
                    include/config/auto.conf
 	$(cmd_crmodverdir)
+	$(Q)test -e include/generated/autoksyms.h || \
+	    touch   include/generated/autoksyms.h
 
 archprepare: archheaders archscripts prepare1 scripts_basic
 
-prepare0: archprepare FORCE
+prepare0: archprepare
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
@@ -1061,7 +1086,7 @@ INSTALL_FW_PATH=$(INSTALL_MOD_PATH)/lib/firmware
 export INSTALL_FW_PATH
 
 PHONY += firmware_install
-firmware_install: FORCE
+firmware_install:
 	@mkdir -p $(objtree)/firmware
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_install
 
@@ -1081,7 +1106,7 @@ PHONY += archscripts
 archscripts:
 
 PHONY += __headers
-__headers: $(version_h) scripts_basic asm-generic archheaders archscripts FORCE
+__headers: $(version_h) scripts_basic asm-generic archheaders archscripts
 	$(Q)$(MAKE) $(build)=scripts build_unifdef
 
 PHONY += headers_install_all
@@ -1192,7 +1217,8 @@ else # CONFIG_MODULES
 # Modules not configured
 # ---------------------------------------------------------------------------
 
-modules modules_install: FORCE
+PHONY += modules modules_install
+modules modules_install:
 	@echo >&2
 	@echo >&2 "The present kernel configuration has modules disabled."
 	@echo >&2 "Type 'make config' and enable loadable module support."
@@ -1283,6 +1309,7 @@ boards := $(sort $(notdir $(boards)))
 board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
 board-dirs := $(sort $(notdir $(board-dirs:/=)))
 
+PHONY += help
 help:
 	@echo  'Cleaning targets:'
 	@echo  '  clean		  - Remove most generated files but keep the config and'
@@ -1453,6 +1480,7 @@ $(clean-dirs):
 clean:	rm-dirs := $(MODVERDIR)
 clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers
 
+PHONY += help
 help:
 	@echo  '  Building external modules.'
 	@echo  '  Syntax: make -C path/to/kernel/src M=$$PWD target'

arch/arm/boot/Makefile

@@ -82,7 +82,6 @@ $(obj)/uImage:	$(obj)/zImage FORCE
 
 $(obj)/bootp/bootp: $(obj)/zImage initrd FORCE
 	$(Q)$(MAKE) $(build)=$(obj)/bootp $@
-	@:
 
 $(obj)/bootpImage: $(obj)/bootp/bootp FORCE
 	$(call if_changed,objcopy)

arch/arm/boot/bootp/Makefile

@@ -17,7 +17,6 @@ targets	:= bootp init.o kernel.o initrd.o
 # Note that bootp.lds picks up kernel.o and initrd.o
 $(obj)/bootp:	$(src)/bootp.lds $(addprefix $(obj)/,init.o kernel.o initrd.o) FORCE
 	$(call if_changed,ld)
-	@:
 
 # kernel.o and initrd.o includes a binary image using
 # .incbin, a dependency which is not tracked automatically
@@ -26,4 +25,4 @@ $(obj)/kernel.o: arch/arm/boot/zImage FORCE
 
 $(obj)/initrd.o: $(INITRD) FORCE
 
-PHONY += $(INITRD) FORCE
+PHONY += $(INITRD)

arch/arm/vdso/Makefile

@@ -74,5 +74,5 @@ $(MODLIB)/vdso: FORCE
 	@mkdir -p $(MODLIB)/vdso
 
 PHONY += vdso_install
-vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso FORCE
+vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso
 	$(call cmd,vdso_install)

arch/h8300/boot/compressed/Makefile

@@ -23,7 +23,6 @@ LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -estartup -T $(obj)/vmlinux.lds \
 
 $(obj)/vmlinux: $(OBJECTS) $(obj)/piggy.o $(LIBGCC) FORCE
 	$(call if_changed,ld)
-	@:
 
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)

arch/ia64/Makefile

@@ -95,8 +95,8 @@ define archhelp
   echo '* unwcheck	- Check vmlinux for invalid unwind info'
 endef
 
-archprepare: make_nr_irqs_h FORCE
-PHONY += make_nr_irqs_h FORCE
+archprepare: make_nr_irqs_h
+PHONY += make_nr_irqs_h
 
-make_nr_irqs_h: FORCE
+make_nr_irqs_h:
 	$(Q)$(MAKE) $(build)=arch/ia64/kernel include/generated/nr-irqs.h

arch/m32r/boot/compressed/Makefile

@@ -19,7 +19,6 @@ LDFLAGS_vmlinux := -T
 
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS) $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
-	@:
 
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)

arch/mn10300/boot/compressed/Makefile

@@ -8,7 +8,6 @@ LDFLAGS_vmlinux := -Ttext $(CONFIG_KERNEL_ZIMAGE_BASE_ADDRESS) -e startup_32
 
 $(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
-	@:
 
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)

arch/nios2/boot/compressed/Makefile

@@ -11,7 +11,6 @@ LDFLAGS_vmlinux := -T
 
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS) $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
-	@:
 
 LDFLAGS_piggy.o := -r --format binary --oformat elf32-littlenios2 -T
 

arch/s390/boot/compressed/Makefile

@@ -22,7 +22,6 @@ OBJECTS += $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o
 LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS)
 	$(call if_changed,ld)
-	@:
 
 sed-sizes := -e 's/^\([0-9a-fA-F]*\) . \(__bss_start\|_end\)$$/\#define SZ\2 0x\1/p'
 

arch/sh/boot/compressed/Makefile

@@ -55,7 +55,6 @@ $(addprefix $(obj)/,$(lib1funcs-y)): $(obj)/%: $(lib1funcs-dir)/% FORCE
 
 $(obj)/vmlinux: $(OBJECTS) $(obj)/piggy.o $(lib1funcs-obj) FORCE
 	$(call if_changed,ld)
-	@:
 
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)

arch/sh/boot/romimage/Makefile

@@ -17,7 +17,6 @@ LDFLAGS_vmlinux := --oformat $(ld-bfd) -Ttext $(load-y) -e romstart \
 
 $(obj)/vmlinux: $(obj)/head.o $(obj-y) $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
-	@:
 
 OBJCOPYFLAGS += -j .empty_zero_page
 

arch/unicore32/boot/Makefile

@@ -31,7 +31,7 @@ $(obj)/uImage: $(obj)/zImage FORCE
 	$(call if_changed,uimage)
 	@echo '  Image $@ is ready'
 
-PHONY += initrd FORCE
+PHONY += initrd
 initrd:
 	@test "$(INITRD)" != "" || \
 	(echo You must specify INITRD; exit -1)

arch/unicore32/boot/compressed/Makefile

@@ -54,7 +54,6 @@ LDFLAGS_vmlinux += -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/head.o $(obj)/piggy.o \
 		$(obj)/misc.o FORCE
 	$(call if_changed,ld)
-	@:
 
 # We now have a PIC decompressor implementation.  Decompressors running
 # from RAM should not define ZTEXTADDR.  Decompressors running directly

arch/x86/boot/compressed/Makefile

@@ -87,7 +87,6 @@ vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
 
 $(obj)/vmlinux: $(vmlinux-objs-y) FORCE
 	$(call if_changed,ld)
-	@:
 
 OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
 $(obj)/vmlinux.bin: vmlinux FORCE

arch/x86/entry/vdso/Makefile

@@ -193,10 +193,10 @@ vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%)
 $(MODLIB)/vdso: FORCE
 	@mkdir -p $(MODLIB)/vdso
 
-$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso FORCE
+$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso
 	$(call cmd,vdso_install)
 
 PHONY += vdso_install $(vdso_img_insttargets)
-vdso_install: $(vdso_img_insttargets) FORCE
+vdso_install: $(vdso_img_insttargets)
 
 clean-files := vdso32.so vdso32.so.dbg vdso64* vdso-image-*.c vdsox32.so*

arch/x86/purgatory/Makefile

@@ -26,7 +26,5 @@ quiet_cmd_bin2c = BIN2C   $@
 
 $(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
 	$(call if_changed,bin2c)
-	@:
-
 
 obj-$(CONFIG_KEXEC_FILE)	+= kexec-purgatory.o

arch/x86/realmode/rm/Makefile

@@ -59,7 +59,6 @@ OBJCOPYFLAGS_realmode.bin := -O binary
 targets += realmode.bin
 $(obj)/realmode.bin: $(obj)/realmode.elf $(obj)/realmode.relocs FORCE
 	$(call if_changed,objcopy)
-	@:
 
 quiet_cmd_relocs = RELOCS  $@
       cmd_relocs = arch/x86/tools/relocs --realmode $< > $@

include/linux/export.h

@@ -38,7 +38,7 @@ extern struct module __this_module;
 
 #ifdef CONFIG_MODULES
 
-#ifndef __GENKSYMS__
+#if defined(__KERNEL__) && !defined(__GENKSYMS__)
 #ifdef CONFIG_MODVERSIONS
 /* Mark the CRC weak since genksyms apparently decides not to
  * generate a checksums for some symbols */
@@ -53,7 +53,7 @@ extern struct module __this_module;
 #endif
 
 /* For every exported symbol, place a struct in the __ksymtab section */
-#define __EXPORT_SYMBOL(sym, sec)				\
+#define ___EXPORT_SYMBOL(sym, sec)				\
 	extern typeof(sym) sym;					\
 	__CRC_SYMBOL(sym, sec)					\
 	static const char __kstrtab_##sym[]			\
@@ -65,6 +65,35 @@ extern struct module __this_module;
 	__attribute__((section("___ksymtab" sec "+" #sym), unused))	\
 	= { (unsigned long)&sym, __kstrtab_##sym }
 
+#if defined(__KSYM_DEPS__)
+
+/*
+ * For fine grained build dependencies, we want to tell the build system
+ * about each possible exported symbol even if they're not actually exported.
+ * We use a string pattern that is unlikely to be valid code that the build
+ * system filters out from the preprocessor output (see ksym_dep_filter
+ * in scripts/Kbuild.include).
+ */
+#define __EXPORT_SYMBOL(sym, sec)	=== __KSYM_##sym ===
+
+#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
+
+#include <linux/kconfig.h>
+#include <generated/autoksyms.h>
+
+#define __EXPORT_SYMBOL(sym, sec)				\
+	__cond_export_sym(sym, sec, config_enabled(__KSYM_##sym))
+#define __cond_export_sym(sym, sec, conf)			\
+	___cond_export_sym(sym, sec, conf)
+#define ___cond_export_sym(sym, sec, enabled)			\
+	__cond_export_sym_##enabled(sym, sec)
+#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
+#define __cond_export_sym_0(sym, sec) /* nothing */
+
+#else
+#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
+#endif
+
 #define EXPORT_SYMBOL(sym)					\
 	__EXPORT_SYMBOL(sym, "")
 

init/Kconfig

@@ -1306,6 +1306,17 @@ source "usr/Kconfig"
 
 endif
 
+choice
+	prompt "Compiler optimization level"
+	default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
+
+config CC_OPTIMIZE_FOR_PERFORMANCE
+	bool "Optimize for performance"
+	help
+	  This is the default optimization level for the kernel, building
+	  with the "-O2" compiler flag for best performance and most
+	  helpful compile-time warnings.
+
 config CC_OPTIMIZE_FOR_SIZE
 	bool "Optimize for size"
 	help
@@ -1314,6 +1325,8 @@ config CC_OPTIMIZE_FOR_SIZE
 
 	  If unsure, say N.
 
+endchoice
+
 config SYSCTL
 	bool
 
@@ -2049,6 +2062,22 @@ config MODULE_COMPRESS_XZ
 
 endchoice
 
+config TRIM_UNUSED_KSYMS
+	bool "Trim unused exported kernel symbols"
+	depends on MODULES && !UNUSED_SYMBOLS
+	help
+	  The kernel and some modules make many symbols available for
+	  other modules to use via EXPORT_SYMBOL() and variants. Depending
+	  on the set of modules being selected in your kernel configuration,
+	  many of those exported symbols might never be used.
+
+	  This option allows for unused exported symbols to be dropped from
+	  the build. In turn, this provides the compiler more opportunities
+	  (especially when using LTO) for optimizing the code and reducing
+	  binary size.  This might have some security advantages as well.
+
+	  If unsure say N.
+
 endif # MODULES
 
 config MODULES_TREE_LOOKUP

kernel/gcov/Kconfig

@@ -37,6 +37,7 @@ config ARCH_HAS_GCOV_PROFILE_ALL
 
 config GCOV_PROFILE_ALL
 	bool "Profile entire Kernel"
+	depends on !COMPILE_TEST
 	depends on GCOV_KERNEL
 	depends on ARCH_HAS_GCOV_PROFILE_ALL
 	default n

scripts/Kbuild.include

@@ -7,6 +7,7 @@ quote   := "
 squote  := '
 empty   :=
 space   := $(empty) $(empty)
+space_escape := _-_SPACE_-_
 
 ###
 # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
@@ -226,10 +227,10 @@ objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
 # See Documentation/kbuild/makefiles.txt for more info
 
 ifneq ($(KBUILD_NOCMDDEP),1)
-# Check if both arguments has same arguments. Result is empty string if equal.
-# User may override this check using make KBUILD_NOCMDDEP=1
-arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
-                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )
+# Check if both arguments are the same including their order. Result is empty
+# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
+arg-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
+                         $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
 else
 arg-check = $(if $(strip $(cmd_$@)),,1)
 endif
@@ -256,10 +257,42 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
 # Execute the command and also postprocess generated .d dependencies file.
 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
 	@set -e;                                                             \
+	$(cmd_and_fixdep), @:)
+
+ifndef CONFIG_TRIM_UNUSED_KSYMS
+
+cmd_and_fixdep =                                                             \
 	$(echo-cmd) $(cmd_$(1));                                             \
 	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
 	rm -f $(depfile);                                                    \
-	mv -f $(dot-target).tmp $(dot-target).cmd, @:)
+	mv -f $(dot-target).tmp $(dot-target).cmd;
+
+else
+
+# Filter out exported kernel symbol names from the preprocessor output.
+# See also __KSYM_DEPS__ in include/linux/export.h.
+# We disable the depfile generation here, so as not to overwrite the existing
+# depfile while fixdep is parsing it.
+flags_nodeps = $(filter-out -Wp$(comma)-M%, $($(1)))
+ksym_dep_filter =                                                            \
+	case "$(1)" in                                                       \
+	  cc_*_c|cpp_i_c)                                                    \
+	    $(CPP) $(call flags_nodeps,c_flags) -D__KSYM_DEPS__ $< ;;        \
+	  as_*_S|cpp_s_S)                                                    \
+	    $(CPP) $(call flags_nodeps,a_flags) -D__KSYM_DEPS__ $< ;;        \
+	  boot*|build*|*cpp_lds_S|dtc|host*|vdso*) : ;;                      \
+	  *) echo "Don't know how to preprocess $(1)" >&2; false ;;          \
+	esac | tr ";" "\n" | sed -rn 's/^.*=== __KSYM_(.*) ===.*$$/KSYM_\1/p'
+
+cmd_and_fixdep =                                                             \
+	$(echo-cmd) $(cmd_$(1));                                             \
+	$(ksym_dep_filter) |                                                 \
+		scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)'          \
+			> $(dot-target).tmp;	                             \
+	rm -f $(depfile);                                                    \
+	mv -f $(dot-target).tmp $(dot-target).cmd;
+
+endif
 
 # Usage: $(call if_changed_rule,foo)
 # Will check if $(cmd_foo) or any of the prerequisites changed,
@@ -341,8 +374,6 @@ endif
 #
 ###############################################################################
 #
-space_escape := %%%SPACE%%%
-#
 define config_filename
 ifneq ($$(CONFIG_$(1)),"")
 $(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))

scripts/Makefile.build

@@ -152,11 +152,11 @@ cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
 $(obj)/%.s: $(src)/%.c FORCE
 	$(call if_changed_dep,cc_s_c)
 
-quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
-cmd_cc_i_c       = $(CPP) $(c_flags)   -o $@ $<
+quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
+cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 
 $(obj)/%.i: $(src)/%.c FORCE
-	$(call if_changed_dep,cc_i_c)
+	$(call if_changed_dep,cpp_i_c)
 
 cmd_gensymtypes =                                                           \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
@@ -266,26 +266,24 @@ endif # CONFIG_STACK_VALIDATION
 
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
-	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
+	$(call cmd_and_fixdep,cc_o_c)					  \
 	$(cmd_modversions)						  \
-	$(cmd_objtool)						  \
-	$(call echo-cmd,record_mcount)					  \
-	$(cmd_record_mcount)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
-	                                              $(dot-target).tmp;  \
-	rm -f $(depfile);						  \
-	mv -f $(dot-target).tmp $(dot-target).cmd
+	$(cmd_objtool)						          \
+	$(call echo-cmd,record_mcount) $(cmd_record_mcount)
 endef
 
 define rule_as_o_S
-	$(call echo-cmd,as_o_S) $(cmd_as_o_S);				  \
-	$(cmd_objtool)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' >    \
-	                                              $(dot-target).tmp;  \
-	rm -f $(depfile);						  \
-	mv -f $(dot-target).tmp $(dot-target).cmd
+	$(call cmd_and_fixdep,as_o_S)					  \
+	$(cmd_objtool)
 endef
 
+# List module undefined symbols (or empty line if not enabled)
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+cmd_undef_syms = $(NM) $@ | sed -n 's/^ \+U //p' | xargs echo
+else
+cmd_undef_syms = echo
+endif
+
 # Built-in and composite module parts
 $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
@@ -296,7 +294,8 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 $(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
-	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
+	@{ echo $(@:.o=.ko); echo $@; \
+	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
 
 quiet_cmd_cc_lst_c = MKLST   $@
       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
@@ -314,11 +313,11 @@ modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
 $(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 $(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 
-quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
-cmd_as_s_S       = $(CPP) $(a_flags)   -o $@ $<
+quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
+cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 
 $(obj)/%.s: $(src)/%.S FORCE
-	$(call if_changed_dep,as_s_S)
+	$(call if_changed_dep,cpp_s_S)
 
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<
@@ -426,7 +425,8 @@ $(call multi_depend, $(multi-used-y), .o, -objs -y)
 
 $(multi-used-m): FORCE
 	$(call if_changed,link_multi-m)
-	@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
+	@{ echo $(@:.o=.ko); echo $(link_multi_deps); \
+	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
 $(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 
 targets += $(multi-used-y) $(multi-used-m)

scripts/Makefile.extrawarn

@@ -24,6 +24,7 @@ warning-1 += $(call cc-option, -Wmissing-prototypes)
 warning-1 += -Wold-style-definition
 warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
+warning-1 += $(call cc-option, -Wunused-const-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 warning-1 += $(call cc-disable-warning, sign-compare)
 

scripts/Makefile.lib

@@ -96,10 +96,10 @@ obj-dirs	:= $(addprefix $(obj)/,$(obj-dirs))
 # Note: Files that end up in two or more modules are compiled without the
 #       KBUILD_MODNAME definition. The reason is that any made-up name would
 #       differ in different configs.
-name-fix = $(subst $(comma),_,$(subst -,_,$1))
-basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
+name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)
+basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
 modname_flags  = $(if $(filter 1,$(words $(modname))),\
-                 -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
+                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))
 
 orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \
                  $(ccflags-y) $(CFLAGS_$(basetarget).o)
@@ -162,7 +162,7 @@ endif
 
 c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
 		 $(__c_flags) $(modkern_cflags)                           \
-		 -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)
+		 $(basename_flags) $(modname_flags)
 
 a_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
 		 $(__a_flags) $(modkern_aflags)

scripts/adjust_autoksyms.sh

+#!/bin/sh
+
+# Script to create/update include/generated/autoksyms.h and dependency files
+#
+# Copyright:	(C) 2016  Linaro Limited
+# Created by:	Nicolas Pitre, January 2016
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+# Create/update the include/generated/autoksyms.h file from the list
+# of all module's needed symbols as recorded on the third line of
+# .tmp_versions/*.mod files.
+#
+# For each symbol being added or removed, the corresponding dependency
+# file's timestamp is updated to force a rebuild of the affected source
+# file. All arguments passed to this script are assumed to be a command
+# to be exec'd to trigger a rebuild of those files.
+
+set -e
+
+cur_ksyms_file="include/generated/autoksyms.h"
+new_ksyms_file="include/generated/autoksyms.h.tmpnew"
+
+info() {
+	if [ "$quiet" != "silent_" ]; then
+		printf "  %-7s %s\n" "$1" "$2"
+	fi
+}
+
+info "CHK" "$cur_ksyms_file"
+
+# Use "make V=1" to debug this script.
+case "$KBUILD_VERBOSE" in
+*1*)
+	set -x
+	;;
+esac
+
+# We need access to CONFIG_ symbols
+case "${KCONFIG_CONFIG}" in
+*/*)
+	. "${KCONFIG_CONFIG}"
+	;;
+*)
+	# Force using a file from the current directory
+	. "./${KCONFIG_CONFIG}"
+esac
+
+# In case it doesn't exist yet...
+if [ -e "$cur_ksyms_file" ]; then touch "$cur_ksyms_file"; fi
+
+# Generate a new ksym list file with symbols needed by the current
+# set of modules.
+cat > "$new_ksyms_file" << EOT
+/*
+ * Automatically generated file; DO NOT EDIT.
+ */
+
+EOT
+sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u |
+while read sym; do
+	if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
+		sym="${sym#_}"
+	fi
+	echo "#define __KSYM_${sym} 1"
+done >> "$new_ksyms_file"
+
+# Special case for modversions (see modpost.c)
+if [ -n "$CONFIG_MODVERSIONS" ]; then
+	echo "#define __KSYM_module_layout 1" >> "$new_ksyms_file"
+fi
+
+# Extract changes between old and new list and touch corresponding
+# dependency files.
+changed=$(
+count=0
+sort "$cur_ksyms_file" "$new_ksyms_file" | uniq -u |
+sed -n 's/^#define __KSYM_\(.*\) 1/\1/p' | tr "A-Z_" "a-z/" |
+while read sympath; do
+	if [ -z "$sympath" ]; then continue; fi
+	depfile="include/config/ksym/${sympath}.h"
+	mkdir -p "$(dirname "$depfile")"
+	touch "$depfile"
+	echo $((count += 1))
+done | tail -1 )
+changed=${changed:-0}
+
+if [ $changed -gt 0 ]; then
+	# Replace the old list with tne new one
+	old=$(grep -c "^#define __KSYM_" "$cur_ksyms_file" || true)
+	new=$(grep -c "^#define __KSYM_" "$new_ksyms_file" || true)
+	info "KSYMS" "symbols: before=$old, after=$new, changed=$changed"
+	info "UPD" "$cur_ksyms_file"
+	mv -f "$new_ksyms_file" "$cur_ksyms_file"
+	# Then trigger a rebuild of affected source files
+	exec $@
+else
+	rm -f "$new_ksyms_file"
+fi

scripts/basic/fixdep.c

@@ -120,13 +120,15 @@
 #define INT_NFIG ntohl(0x4e464947)
 #define INT_FIG_ ntohl(0x4649475f)
 
+int insert_extra_deps;
 char *target;
 char *depfile;
 char *cmdline;
 
 static void usage(void)
 {
-	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
+	fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
+	fprintf(stderr, " -e  insert extra dependencies given on stdin\n");
 	exit(1);
 }
 
@@ -138,6 +140,40 @@ static void print_cmdline(void)
 	printf("cmd_%s := %s\n\n", target, cmdline);
 }
 
+/*
+ * Print out a dependency path from a symbol name
+ */
+static void print_config(const char *m, int slen)
+{
+	int c, i;
+
+	printf("    $(wildcard include/config/");
+	for (i = 0; i < slen; i++) {
+		c = m[i];
+		if (c == '_')
+			c = '/';
+		else
+			c = tolower(c);
+		putchar(c);
+	}
+	printf(".h) \\\n");
+}
+
+static void do_extra_deps(void)
+{
+	if (insert_extra_deps) {
+		char buf[80];
+		while(fgets(buf, sizeof(buf), stdin)) {
+			int len = strlen(buf);
+			if (len < 2 || buf[len-1] != '\n') {
+				fprintf(stderr, "fixdep: bad data on stdin\n");
+				exit(1);
+			}
+			print_config(buf, len-1);
+		}
+	}
+}
+
 struct item {
 	struct item	*next;
 	unsigned int	len;
@@ -197,23 +233,12 @@ static void define_config(const char *name, int len, unsigned int hash)
 static void use_config(const char *m, int slen)
 {
 	unsigned int hash = strhash(m, slen);
-	int c, i;
 
 	if (is_defined_config(m, slen, hash))
 	    return;
 
 	define_config(m, slen, hash);
-
-	printf("    $(wildcard include/config/");
-	for (i = 0; i < slen; i++) {
-		c = m[i];
-		if (c == '_')
-			c = '/';
-		else
-			c = tolower(c);
-		putchar(c);
-	}
-	printf(".h) \\\n");
+	print_config(m, slen);
 }
 
 static void parse_config_file(const char *map, size_t len)
@@ -250,7 +275,7 @@ static void parse_config_file(const char *map, size_t len)
 	}
 }
 
-/* test is s ends in sub */
+/* test if s ends in sub */
 static int strrcmp(const char *s, const char *sub)
 {
 	int slen = strlen(s);
@@ -333,6 +358,7 @@ static void parse_dep_file(void *map, size_t len)
 
 			/* Ignore certain dependencies */
 			if (strrcmp(s, "include/generated/autoconf.h") &&
+			    strrcmp(s, "include/generated/autoksyms.h") &&
 			    strrcmp(s, "arch/um/include/uml-config.h") &&
 			    strrcmp(s, "include/linux/kconfig.h") &&
 			    strrcmp(s, ".ver")) {
@@ -378,6 +404,8 @@ static void parse_dep_file(void *map, size_t len)
 		exit(1);
 	}
 
+	do_extra_deps();
+
 	printf("\n%s: $(deps_%s)\n\n", target, target);
 	printf("$(deps_%s):\n", target);
 }
@@ -434,7 +462,10 @@ int main(int argc, char *argv[])
 {
 	traps();
 
-	if (argc != 4)
+	if (argc == 5 && !strcmp(argv[1], "-e")) {
+		insert_extra_deps = 1;
+		argv++;
+	} else if (argc != 4)
 		usage();
 
 	depfile = argv[1];

scripts/genksyms/genksyms.c

@@ -873,5 +873,8 @@ int main(int argc, char **argv)
 			(double)nsyms / (double)HASH_BUCKETS);
 	}
 
+	if (dumpfile)
+		fclose(dumpfile);
+
 	return errors != 0;
 }

tools/build/Makefile.build

@@ -58,8 +58,8 @@ quiet_cmd_mkdir = MKDIR    $(dir $@)
 quiet_cmd_cc_o_c = CC       $@
       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
-quiet_cmd_cc_i_c = CPP      $@
-      cmd_cc_i_c = $(CC) $(c_flags) -E -o $@ $<
+quiet_cmd_cpp_i_c = CPP      $@
+      cmd_cpp_i_c = $(CC) $(c_flags) -E -o $@ $<
 
 quiet_cmd_cc_s_c = AS       $@
       cmd_cc_s_c = $(CC) $(c_flags) -S -o $@ $<
@@ -83,11 +83,11 @@ $(OUTPUT)%.o: %.S FORCE
 
 $(OUTPUT)%.i: %.c FORCE
 	$(call rule_mkdir)
-	$(call if_changed_dep,cc_i_c)
+	$(call if_changed_dep,cpp_i_c)
 
 $(OUTPUT)%.s: %.S FORCE
 	$(call rule_mkdir)
-	$(call if_changed_dep,cc_i_c)
+	$(call if_changed_dep,cpp_i_c)
 
 $(OUTPUT)%.s: %.c FORCE
 	$(call rule_mkdir)