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

Pull kbuild updates from Michal Marek:
 - make clean also considers $(extra-m) and $(extra-) to be consistent
 - cleanup and fixes in scripts/Makefile.host
 - allow to override the name of the Python 2 executable with make
   PYTHON=... (only needed for ia64 in practice)
 - option to split debugingo into *.dwo files to save disk space if the
   compiler supports it (CONFIG_DEBUG_INFO_SPLIT)
 - option to use dwarf4 debuginfo if the compiler supports it
   (CONFIG_DEBUG_INFO_DWARF4)
 - fix for disabling certain warnings with clang
 - fix for unneeded rebuild with dash when a command contains
   backslashes

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  kbuild: Fix handling of backslashes in *.cmd files
  kbuild, LLVMLinux: Supress warnings unless W=1-3
  Kbuild: Add a option to enable dwarf4 v2
  kbuild: Support split debug info v4
  kbuild: allow to override Python command name
  kbuild: clean-up and bug fix of scripts/Makefile.host
  kbuild: clean up scripts/Makefile.host
  kbuild: drop shared library support from Makefile.host
  kbuild: fix a bug of C++ host program handling
  kbuild: fix a typo in scripts/Makefile.host
  scripts/Makefile.clean: clean also $(extra-m) and $(extra-)

9 files changed, 75 insertions, 103 deletions

diff --git a/.gitignore b/.gitignore
index f4c0b091dcf..e213b27f392 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,6 +34,7 @@
 *.gcno
 modules.builtin
 Module.symvers
+*.dwo
 
 #
 # Top-level generic files
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index c600e2f44a6..764f5991a3f 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -23,11 +23,10 @@ This document describes the Linux kernel Makefiles.
 	=== 4 Host Program support
 	   --- 4.1 Simple Host Program
 	   --- 4.2 Composite Host Programs
-	   --- 4.3 Defining shared libraries
-	   --- 4.4 Using C++ for host programs
-	   --- 4.5 Controlling compiler options for host programs
-	   --- 4.6 When host programs are actually built
-	   --- 4.7 Using hostprogs-$(CONFIG_FOO)
+	   --- 4.3 Using C++ for host programs
+	   --- 4.4 Controlling compiler options for host programs
+	   --- 4.5 When host programs are actually built
+	   --- 4.6 Using hostprogs-$(CONFIG_FOO)
 
 	=== 5 Kbuild clean infrastructure
 
@@ -643,29 +642,7 @@ Both possibilities are described in the following.
 	Finally, the two .o files are linked to the executable, lxdialog.
 	Note: The syntax <executable>-y is not permitted for host-programs.
 
---- 4.3 Defining shared libraries
-
-	Objects with extension .so are considered shared libraries, and
-	will be compiled as position independent objects.
-	Kbuild provides support for shared libraries, but the usage
-	shall be restricted.
-	In the following example the libkconfig.so shared library is used
-	to link the executable conf.
-
-	Example:
-		#scripts/kconfig/Makefile
-		hostprogs-y     := conf
-		conf-objs       := conf.o libkconfig.so
-		libkconfig-objs := expr.o type.o
-
-	Shared libraries always require a corresponding -objs line, and
-	in the example above the shared library libkconfig is composed by
-	the two objects expr.o and type.o.
-	expr.o and type.o will be built as position independent code and
-	linked as a shared library libkconfig.so. C++ is not supported for
-	shared libraries.
-
---- 4.4 Using C++ for host programs
+--- 4.3 Using C++ for host programs
 
 	kbuild offers support for host programs written in C++. This was
 	introduced solely to support kconfig, and is not recommended
@@ -688,7 +665,7 @@ Both possibilities are described in the following.
 		qconf-cxxobjs := qconf.o
 		qconf-objs    := check.o
 
---- 4.5 Controlling compiler options for host programs
+--- 4.4 Controlling compiler options for host programs
 
 	When compiling host programs, it is possible to set specific flags.
 	The programs will always be compiled utilising $(HOSTCC) passed
@@ -716,7 +693,7 @@ Both possibilities are described in the following.
 	When linking qconf, it will be passed the extra option
 	"-L$(QTDIR)/lib".
 
---- 4.6 When host programs are actually built
+--- 4.5 When host programs are actually built
 
 	Kbuild will only build host-programs when they are referenced
 	as a prerequisite.
@@ -747,7 +724,7 @@ Both possibilities are described in the following.
 	This will tell kbuild to build lxdialog even if not referenced in
 	any rule.
 
---- 4.7 Using hostprogs-$(CONFIG_FOO)
+--- 4.6 Using hostprogs-$(CONFIG_FOO)
 
 	A typical pattern in a Kbuild file looks like this:
 
diff --git a/Makefile b/Makefile
index a897c50db51..ada00f0d2a1 100644
--- a/Makefile
+++ b/Makefile
@@ -372,6 +372,7 @@ GENKSYMS	= scripts/genksyms/genksyms
 INSTALLKERNEL  := installkernel
 DEPMOD		= /sbin/depmod
 PERL		= perl
+PYTHON		= python
 CHECK		= sparse
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
@@ -422,7 +423,7 @@ KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(S
 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
 export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP
-export MAKE AWK GENKSYMS INSTALLKERNEL PERL UTS_MACHINE
+export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
@@ -687,6 +688,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
 # See modpost pattern 2
 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.
@@ -710,9 +712,16 @@ endif
 KBUILD_CFLAGS   += $(call cc-option, -fno-var-tracking-assignments)
 
 ifdef CONFIG_DEBUG_INFO
+ifdef CONFIG_DEBUG_INFO_SPLIT
+KBUILD_CFLAGS   += $(call cc-option, -gsplit-dwarf, -g)
+else
 KBUILD_CFLAGS	+= -g
+endif
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
 endif
+ifdef CONFIG_DEBUG_INFO_DWARF4
+KBUILD_CFLAGS	+= $(call cc-option, -gdwarf-4,)
+endif
 
 ifdef CONFIG_DEBUG_INFO_REDUCED
 KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly) \
@@ -1398,6 +1407,7 @@ clean: $(clean-dirs)
 	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
 		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
 		-o -name '*.ko.*' \
+		-o -name '*.dwo'  \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
 		-o -name '*.symtypes' -o -name 'modules.order' \
 		-o -name modules.builtin -o -name '.tmp_*.o.*' \
diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile
index f37238f45bc..5441b14994f 100644
--- a/arch/ia64/Makefile
+++ b/arch/ia64/Makefile
@@ -76,7 +76,7 @@ vmlinux.gz: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $@
 
 unwcheck: vmlinux
-	-$(Q)READELF=$(READELF) python $(srctree)/arch/ia64/scripts/unwcheck.py $<
+	-$(Q)READELF=$(READELF) $(PYTHON) $(srctree)/arch/ia64/scripts/unwcheck.py $<
 
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cb45f59685e..07c28323f88 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -143,6 +143,30 @@ config DEBUG_INFO_REDUCED
 	  DEBUG_INFO build and compile times are reduced too.
 	  Only works with newer gcc versions.
 
+config DEBUG_INFO_SPLIT
+	bool "Produce split debuginfo in .dwo files"
+	depends on DEBUG_INFO
+	help
+	  Generate debug info into separate .dwo files. This significantly
+	  reduces the build directory size for builds with DEBUG_INFO,
+	  because it stores the information only once on disk in .dwo
+	  files instead of multiple times in object files and executables.
+	  In addition the debug information is also compressed.
+
+	  Requires recent gcc (4.7+) and recent gdb/binutils.
+	  Any tool that packages or reads debug information would need
+	  to know about the .dwo files and include them.
+	  Incompatible with older versions of ccache.
+
+config DEBUG_INFO_DWARF4
+	bool "Generate dwarf4 debuginfo"
+	depends on DEBUG_INFO
+	help
+	  Generate dwarf4 debug info. This requires recent versions
+	  of gcc and gdb. It makes the debug information larger.
+	  But it significantly improves the success of resolving
+	  variables in gdb on optimized code.
+
 config ENABLE_WARN_DEPRECATED
 	bool "Enable __deprecated logic"
 	default y
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 122f95c9586..8a9a4e1c7ea 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -215,11 +215,13 @@ else
 arg-check = $(if $(strip $(cmd_$@)),,1)
 endif
 
-# >'< substitution is for echo to work,
-# >$< substitution to preserve $ when reloading .cmd file
-# note: when using inline perl scripts [perl -e '...$$t=1;...']
-# in $(cmd_xxx) double $$ your perl vars
-make-cmd = $(subst \\,\\\\,$(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))))
+# Replace >$< with >$$< to preserve $ when reloading the .cmd file
+# (needed for make)
+# Replace >#< with >\#< to avoid starting a comment in the .cmd file
+# (needed for make)
+# Replace >'< with >'\''< to be able to enclose the whole string in '...'
+# (needed for the shell)
+make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
 
 # Find any prerequisites that is newer than target or that does not exist.
 # PHONY targets skipped in both cases.
@@ -230,7 +232,7 @@ any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
 if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
 	@set -e;                                                             \
 	$(echo-cmd) $(cmd_$(1));                                             \
-	echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
+	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
 
 # Execute the command and also postprocess generated .d dependencies file.
 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 686cb0d31c7..a651cee84f2 100644
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -40,8 +40,8 @@ subdir-ymn	:= $(addprefix $(obj)/,$(subdir-ymn))
 # build a list of files to remove, usually relative to the current
 # directory
 
-__clean-files	:= $(extra-y) $(always)                  \
-		   $(targets) $(clean-files)             \
+__clean-files	:= $(extra-y) $(extra-m) $(extra-)       \
+		   $(always) $(targets) $(clean-files)   \
 		   $(host-progs)                         \
 		   $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
 
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 65643506c71..f734033af21 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -26,16 +26,6 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 
-# Clang
-warning-1 += $(call cc-disable-warning, initializer-overrides)
-warning-1 += $(call cc-disable-warning, unused-value)
-warning-1 += $(call cc-disable-warning, format)
-warning-1 += $(call cc-disable-warning, unknown-warning-option)
-warning-1 += $(call cc-disable-warning, sign-compare)
-warning-1 += $(call cc-disable-warning, format-zero-length)
-warning-1 += $(call cc-disable-warning, uninitialized)
-warning-1 += $(call cc-option, -fcatch-undefined-behavior)
-
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
 warning-2 += -Wdisabled-optimization
@@ -64,4 +54,15 @@ ifeq ("$(strip $(warning))","")
 endif
 
 KBUILD_CFLAGS += $(warning)
+else
+
+ifeq ($(COMPILER),clang)
+KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
+KBUILD_CFLAGS += $(call cc-disable-warning, format)
+KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
+KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
+KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
+endif
 endif
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 66893643fd7..ab5980f9171 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -20,21 +20,12 @@
 # Will compile qconf as a C++ program, and menu as a C program.
 # They are linked as C++ code to the executable qconf
 
-# hostprogs-y := conf
-# conf-objs  := conf.o libkconfig.so
-# libkconfig-objs := expr.o type.o
-# Will create a shared library named libkconfig.so that consists of
-# expr.o and type.o (they are both compiled as C code and the object files
-# are made as position independent code).
-# conf.c is compiled as a C program, and conf.o is linked together with
-# libkconfig.so as the executable conf.
-# Note: Shared libraries consisting of C++ files are not supported
-
 __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
 
 # C code
 # Executables compiled from a single .c file
-host-csingle	:= $(foreach m,$(__hostprogs),$(if $($(m)-objs),,$(m)))
+host-csingle	:= $(foreach m,$(__hostprogs), \
+			$(if $($(m)-objs)$($(m)-cxxobjs),,$(m)))
 
 # C executables linked based on several .o files
 host-cmulti	:= $(foreach m,$(__hostprogs),\
@@ -44,33 +35,17 @@ host-cmulti	:= $(foreach m,$(__hostprogs),\
 host-cobjs	:= $(sort $(foreach m,$(__hostprogs),$($(m)-objs)))
 
 # C++ code
-# C++ executables compiled from at least on .cc file
+# C++ executables compiled from at least one .cc file
 # and zero or more .c files
 host-cxxmulti	:= $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
 
 # C++ Object (.o) files compiled from .cc files
 host-cxxobjs	:= $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
 
-# Shared libaries (only .c supported)
-# Shared libraries (.so) - all .so files referenced in "xxx-objs"
-host-cshlib	:= $(sort $(filter %.so, $(host-cobjs)))
-# Remove .so files from "xxx-objs"
-host-cobjs	:= $(filter-out %.so,$(host-cobjs))
-
-#Object (.o) files used by the shared libaries
-host-cshobjs	:= $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
-
 # output directory for programs/.o files
-# hostprogs-y := tools/build may have been specified. Retrieve directory
-host-objdirs := $(foreach f,$(__hostprogs), $(if $(dir $(f)),$(dir $(f))))
-# directory of .o files from prog-objs notation
-host-objdirs += $(foreach f,$(host-cmulti),                  \
-                    $(foreach m,$($(f)-objs),                \
-                        $(if $(dir $(m)),$(dir $(m)))))
-# directory of .o files from prog-cxxobjs notation
-host-objdirs += $(foreach f,$(host-cxxmulti),                  \
-                    $(foreach m,$($(f)-cxxobjs),                \
-                        $(if $(dir $(m)),$(dir $(m)))))
+# hostprogs-y := tools/build may have been specified.
+# Retrieve also directory of .o files from prog-objs or prog-cxxobjs notation
+host-objdirs := $(dir $(__hostprogs) $(host-cobjs) $(host-cxxobjs))
 
 host-objdirs := $(strip $(sort $(filter-out ./,$(host-objdirs))))
 
@@ -81,8 +56,6 @@ host-cmulti	:= $(addprefix $(obj)/,$(host-cmulti))
 host-cobjs	:= $(addprefix $(obj)/,$(host-cobjs))
 host-cxxmulti	:= $(addprefix $(obj)/,$(host-cxxmulti))
 host-cxxobjs	:= $(addprefix $(obj)/,$(host-cxxobjs))
-host-cshlib	:= $(addprefix $(obj)/,$(host-cshlib))
-host-cshobjs	:= $(addprefix $(obj)/,$(host-cshobjs))
 host-objdirs    := $(addprefix $(obj)/,$(host-objdirs))
 
 obj-dirs += $(host-objdirs)
@@ -123,7 +96,7 @@ quiet_cmd_host-cmulti	= HOSTLD  $@
       cmd_host-cmulti	= $(HOSTCC) $(HOSTLDFLAGS) -o $@ \
 			  $(addprefix $(obj)/,$($(@F)-objs)) \
 			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
-$(host-cmulti): $(obj)/%: $(host-cobjs) $(host-cshlib) FORCE
+$(host-cmulti): $(obj)/%: $(host-cobjs) FORCE
 	$(call if_changed,host-cmulti)
 
 # Create .o file from a single .c file
@@ -140,7 +113,7 @@ quiet_cmd_host-cxxmulti	= HOSTLD  $@
 			  $(foreach o,objs cxxobjs,\
 			  $(addprefix $(obj)/,$($(@F)-$(o)))) \
 			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
-$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) $(host-cshlib) FORCE
+$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) FORCE
 	$(call if_changed,host-cxxmulti)
 
 # Create .o file from a single .cc (C++) file
@@ -149,21 +122,5 @@ quiet_cmd_host-cxxobjs	= HOSTCXX $@
 $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
 	$(call if_changed_dep,host-cxxobjs)
 
-# Compile .c file, create position independent .o file
-# host-cshobjs -> .o
-quiet_cmd_host-cshobjs	= HOSTCC  -fPIC $@
-      cmd_host-cshobjs	= $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
-$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
-	$(call if_changed_dep,host-cshobjs)
-
-# Link a shared library, based on position independent .o files
-# *.o -> .so shared library (host-cshlib)
-quiet_cmd_host-cshlib	= HOSTLLD -shared $@
-      cmd_host-cshlib	= $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
-			  $(addprefix $(obj)/,$($(@F:.so=-objs))) \
-			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
-$(host-cshlib): $(obj)/%: $(host-cshobjs) FORCE
-	$(call if_changed,host-cshlib)
-
 targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
-	   $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs)
+	   $(host-cxxmulti) $(host-cxxobjs)