Merge tag 'kbuild-thinar-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild thin archives updates from Masahiro Yamada:
 "Thin archives migration by Nicholas Piggin.

  THIN_ARCHIVES has been available for a while as an optional feature
  only for PowerPC architecture, but we do not need two different
  intermediate-artifact schemes.

  Using thin archives instead of conventional incremental linking has
  various advantages:

   - save disk space for builds

   - speed-up building a little

   - fix some link issues (for example, allyesconfig on ARM) due to more
     flexibility for the final linking

   - work better with dead code elimination we are planning

  As discussed before, this migration has been done unconditionally so
  that any problems caused by this will show up with "git bisect".

  With testing with 0-day and linux-next, some architectures actually
  showed up problems, but they were trivial and all fixed now"

* tag 'kbuild-thinar-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  tile: remove unneeded extra-y in Makefile
  kbuild: thin archives make default for all archs
  x86/um: thin archives build fix
  tile: thin archives fix linking
  ia64: thin archives fix linking
  sh: thin archives fix linking
  kbuild: handle libs-y archives separately from built-in.o archives
  kbuild: thin archives use P option to ar
  kbuild: thin archives final link close --whole-archives option
  ia64: remove unneeded extra-y in Makefile.gate
  tile: fix dependency and .*.cmd inclusion for incremental build
  sparc64: Use indirect calls in hamming weight stubs

Documentation/kbuild/kbuild.txt

@@ -236,5 +236,9 @@ Files specified with KBUILD_VMLINUX_INIT are linked first.
 KBUILD_VMLINUX_MAIN
 --------------------------------------------------
 All object files for the main part of vmlinux.
-KBUILD_VMLINUX_INIT and KBUILD_VMLINUX_MAIN together specify
-all the object files used to link vmlinux.
+
+KBUILD_VMLINUX_LIBS
+--------------------------------------------------
+All .a "lib" files for vmlinux.
+KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together
+specify all the object files used to link vmlinux.

Documentation/process/changes.rst

@@ -31,7 +31,7 @@ you probably needn't concern yourself with isdn4k-utils.
 ====================== ===============  ========================================
 GNU C                  3.2              gcc --version
 GNU make               3.81             make --version
-binutils               2.12             ld -v
+binutils               2.20             ld -v
 util-linux             2.10o            fdformat --version
 module-init-tools      0.9.10           depmod -V
 e2fsprogs              1.41.4           e2fsck -V
@@ -75,10 +75,9 @@ You will need GNU make 3.81 or later to build the kernel.
 Binutils
 --------
 
-Linux on IA-32 has recently switched from using ``as86`` to using ``gas`` for
-assembling the 16-bit boot code, removing the need for ``as86`` to compile
-your kernel.  This change does, however, mean that you need a recent
-release of binutils.
+The build system has, as of 4.13, switched to using thin archives (`ar T`)
+rather than incremental linking (`ld -r`) for built-in.o intermediate steps.
+This requires binutils 2.20 or newer.
 
 Perl
 ----

Makefile

@@ -944,19 +944,19 @@ core-y		:= $(patsubst %/, %/built-in.o, $(core-y))
 drivers-y	:= $(patsubst %/, %/built-in.o, $(drivers-y))
 net-y		:= $(patsubst %/, %/built-in.o, $(net-y))
 libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
-libs-y2		:= $(patsubst %/, %/built-in.o, $(libs-y))
-libs-y		:= $(libs-y1) $(libs-y2)
+libs-y2		:= $(filter-out %.a, $(patsubst %/, %/built-in.o, $(libs-y)))
 virt-y		:= $(patsubst %/, %/built-in.o, $(virt-y))
 
 # Externally visible symbols (used by link-vmlinux.sh)
 export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
-export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y) $(virt-y)
+export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y2) $(drivers-y) $(net-y) $(virt-y)
+export KBUILD_VMLINUX_LIBS := $(libs-y1)
 export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
 export LDFLAGS_vmlinux
 # used by scripts/pacmage/Makefile
 export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
 
-vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)
+vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) $(KBUILD_VMLINUX_LIBS)
 
 # 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

arch/Kconfig

@@ -550,7 +550,7 @@ config CC_STACKPROTECTOR_STRONG
 endchoice
 
 config THIN_ARCHIVES
-	bool
+	def_bool y
 	help
 	  Select this if the architecture wants to use thin archives
 	  instead of ld -r to create the built-in.o files.

arch/ia64/kernel/Makefile.gate

@@ -1,8 +1,8 @@
 # The gate DSO image is built using a special linker script.
 
-targets += gate.so gate-syms.o
+targets += gate.so gate.lds gate.o gate-dummy.o
 
-extra-y += gate.so gate-syms.o gate.lds gate.o
+obj-y += gate-syms.o
 
 CPPFLAGS_gate.lds := -P -C -U$(ARCH)
 
@@ -14,13 +14,14 @@ GATECFLAGS_gate.so = -shared -s -Wl,-soname=linux-gate.so.1 \
 $(obj)/gate.so: $(obj)/gate.lds $(obj)/gate.o FORCE
 	$(call if_changed,gate)
 
-$(obj)/built-in.o: $(obj)/gate-syms.o
-$(obj)/built-in.o: ld_flags += -R $(obj)/gate-syms.o
-
-GATECFLAGS_gate-syms.o = -r
-$(obj)/gate-syms.o: $(obj)/gate.lds $(obj)/gate.o FORCE
+GATECFLAGS_gate-dummy.o = -r
+$(obj)/gate-dummy.o: $(obj)/gate.lds $(obj)/gate.o FORCE
 	$(call if_changed,gate)
 
+LDFLAGS_gate-syms.o := -r -R
+$(obj)/gate-syms.o: $(obj)/gate-dummy.o FORCE
+	$(call if_changed,ld)
+
 # gate-data.o contains the gate DSO image as data in section .data..gate.
 # We must build gate.so before we can assemble it.
 # Note: kbuild does not track this dependency due to usage of .incbin

arch/powerpc/Kconfig

@@ -463,14 +463,6 @@ config MPROFILE_KERNEL
 	depends on PPC64 && CPU_LITTLE_ENDIAN
 	def_bool !DISABLE_MPROFILE_KERNEL
 
-config USE_THIN_ARCHIVES
-	bool "Build the kernel using thin archives"
-	default n
-	select THIN_ARCHIVES
-	help
-	  Build the kernel using thin archives.
-	  If you're unsure say N.
-
 config IOMMU_HELPER
 	def_bool PPC64
 

arch/sh/kernel/vsyscall/Makefile

@@ -1,11 +1,11 @@
-obj-y += vsyscall.o vsyscall-syscall.o
+obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
 
 $(obj)/vsyscall-syscall.o: \
 	$(foreach F,trapa,$(obj)/vsyscall-$F.so)
 
 # Teach kbuild about targets
 targets += $(foreach F,trapa,vsyscall-$F.o vsyscall-$F.so)
-targets += vsyscall-note.o vsyscall.lds
+targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o
 
 # The DSO images are built using a special linker script
 quiet_cmd_syscall = SYSCALL $@
@@ -26,11 +26,11 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
 # We also create a special relocatable object that should mirror the symbol
 # table and layout of the linked DSO.  With ld -R we can then refer to
 # these symbols in the kernel code rather than hand-coded addresses.
-extra-y += vsyscall-syms.o
-$(obj)/built-in.o: $(obj)/vsyscall-syms.o
-$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
-
-SYSCFLAGS_vsyscall-syms.o = -r
-$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
+SYSCFLAGS_vsyscall-dummy.o = -r
+$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
 			$(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
 	$(call if_changed,syscall)
+
+LDFLAGS_vsyscall-syms.o := -r -R
+$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o FORCE
+	$(call if_changed,ld)

arch/sparc/lib/hweight.S

@@ -4,9 +4,9 @@
 	.text
 	.align	32
 ENTRY(__arch_hweight8)
-	ba,pt	%xcc, __sw_hweight8
+	sethi	%hi(__sw_hweight8), %g1
+	jmpl	%g1 + %lo(__sw_hweight8), %g0
 	 nop
-	nop
 ENDPROC(__arch_hweight8)
 EXPORT_SYMBOL(__arch_hweight8)
 	.section	.popc_3insn_patch, "ax"
@@ -17,9 +17,9 @@ EXPORT_SYMBOL(__arch_hweight8)
 	.previous
 
 ENTRY(__arch_hweight16)
-	ba,pt	%xcc, __sw_hweight16
+	sethi	%hi(__sw_hweight16), %g1
+	jmpl	%g1 + %lo(__sw_hweight16), %g0
 	 nop
-	nop
 ENDPROC(__arch_hweight16)
 EXPORT_SYMBOL(__arch_hweight16)
 	.section	.popc_3insn_patch, "ax"
@@ -30,9 +30,9 @@ EXPORT_SYMBOL(__arch_hweight16)
 	.previous
 
 ENTRY(__arch_hweight32)
-	ba,pt	%xcc, __sw_hweight32
+	sethi	%hi(__sw_hweight32), %g1
+	jmpl	%g1 + %lo(__sw_hweight32), %g0
 	 nop
-	nop
 ENDPROC(__arch_hweight32)
 EXPORT_SYMBOL(__arch_hweight32)
 	.section	.popc_3insn_patch, "ax"
@@ -43,9 +43,9 @@ EXPORT_SYMBOL(__arch_hweight32)
 	.previous
 
 ENTRY(__arch_hweight64)
-	ba,pt	%xcc, __sw_hweight64
+	sethi	%hi(__sw_hweight16), %g1
+	jmpl	%g1 + %lo(__sw_hweight16), %g0
 	 nop
-	nop
 ENDPROC(__arch_hweight64)
 EXPORT_SYMBOL(__arch_hweight64)
 	.section	.popc_3insn_patch, "ax"

arch/tile/kernel/vdso/Makefile

@@ -5,15 +5,14 @@ vdso-syms = rt_sigreturn gettimeofday
 obj-vdso = $(patsubst %, v%.o, $(vdso-syms))
 
 # Build rules
-targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds
+targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-dummy.o
 obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 
 # vdso32 is only for tilegx -m32 compat task.
 VDSO32-$(CONFIG_COMPAT) := y
 
-obj-y += vdso.o
+obj-y += vdso.o vdso-syms.o
 obj-$(VDSO32-y) += vdso32.o
-extra-y += vdso.lds
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
 # vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -42,23 +41,22 @@ $(obj)/vdso.o: $(obj)/vdso.so
 
 # link rule for the .so file, .lds has to be first
 SYSCFLAGS_vdso.so.dbg = $(c_flags)
-$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso)
+$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE
 	$(call if_changed,vdsold)
 
-
 # We also create a special relocatable object that should mirror the symbol
 # table and layout of the linked DSO.  With ld -R we can then refer to
 # these symbols in the kernel code rather than hand-coded addresses.
-extra-y += vdso-syms.o
-$(obj)/built-in.o: $(obj)/vdso-syms.o
-$(obj)/built-in.o: ld_flags += -R $(obj)/vdso-syms.o
 
 SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \
                             $(call cc-ldoption, -Wl$(comma)--hash-style=both)
-SYSCFLAGS_vdso_syms.o = -r
-$(obj)/vdso-syms.o: $(src)/vdso.lds $(obj)/vrt_sigreturn.o FORCE
+SYSCFLAGS_vdso_dummy.o = -r
+$(obj)/vdso-dummy.o: $(src)/vdso.lds $(obj)/vrt_sigreturn.o FORCE
 	$(call if_changed,vdsold)
 
+LDFLAGS_vdso-syms.o := -r -R
+$(obj)/vdso-syms.o: $(obj)/vdso-dummy.o FORCE
+	$(call if_changed,ld)
 
 # strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S
@@ -96,17 +94,17 @@ KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
 KBUILD_CFLAGS_32 += -m32 -fPIC -shared
 
 obj-vdso32 = $(patsubst %, v%32.o, $(vdso-syms))
-obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 
 targets += $(obj-vdso32) vdso32.so vdso32.so.dbg
+obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 
 $(obj-vdso32:%=%): KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
 $(obj-vdso32:%=%): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
 
-$(obj)/vgettimeofday32.o: $(obj)/vgettimeofday.c
+$(obj)/vgettimeofday32.o: $(obj)/vgettimeofday.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
-$(obj)/vrt_sigreturn32.o: $(obj)/vrt_sigreturn.S
+$(obj)/vrt_sigreturn32.o: $(obj)/vrt_sigreturn.S FORCE
 	$(call if_changed,as_o_S)
 
 # Force dependency
@@ -114,5 +112,5 @@ $(obj)/vdso32.o: $(obj)/vdso32.so
 
 SYSCFLAGS_vdso32.so.dbg = -m32 -shared -s -Wl,-soname=linux-vdso32.so.1 \
 			    $(call cc-ldoption, -Wl$(comma)--hash-style=both)
-$(obj)/vdso32.so.dbg: $(src)/vdso.lds $(obj-vdso32)
+$(obj)/vdso32.so.dbg: $(src)/vdso.lds $(obj-vdso32) FORCE
 	$(call if_changed,vdsold)

arch/x86/um/vdso/Makefile

@@ -53,7 +53,7 @@ CFLAGS_REMOVE_vdso-note.o = -pg -fprofile-arcs -ftest-coverage
 CFLAGS_REMOVE_um_vdso.o = -pg -fprofile-arcs -ftest-coverage
 
 targets += vdso-syms.lds
-obj-$(VDSO64-y)			+= vdso-syms.lds
+extra-$(VDSO64-y)			+= vdso-syms.lds
 
 #
 # Match symbols in the DSO that look like VDSO*; produce a file of constants.

scripts/Makefile.build

@@ -437,8 +437,8 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ;
 ifdef builtin-target
 
 ifdef CONFIG_THIN_ARCHIVES
-  cmd_make_builtin = rm -f $@; $(AR) rcST$(KBUILD_ARFLAGS)
-  cmd_make_empty_builtin = rm -f $@; $(AR) rcST$(KBUILD_ARFLAGS)
+  cmd_make_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
+  cmd_make_empty_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
   quiet_cmd_link_o_target = AR      $@
 else
   cmd_make_builtin = $(LD) $(ld_flags) -r -o
@@ -478,7 +478,7 @@ ifdef lib-target
 quiet_cmd_link_l_target = AR      $@
 
 ifdef CONFIG_THIN_ARCHIVES
-  cmd_link_l_target = rm -f $@; $(AR) rcsT$(KBUILD_ARFLAGS) $@ $(lib-y)
+  cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
 else
   cmd_link_l_target = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@ $(lib-y)
 endif
@@ -531,7 +531,7 @@ cmd_link_multi-link = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secana
 
 ifdef CONFIG_THIN_ARCHIVES
   quiet_cmd_link_multi-y = AR      $@
-  cmd_link_multi-y = rm -f $@; $(AR) rcST$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
+  cmd_link_multi-y = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
 else
   quiet_cmd_link_multi-y = LD      $@
   cmd_link_multi-y = $(cmd_link_multi-link)

scripts/link-vmlinux.sh

@@ -3,9 +3,12 @@
 # link vmlinux
 #
 # vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
-# $(KBUILD_VMLINUX_MAIN). Most are built-in.o files from top-level directories
-# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
-# Ordering when linking is important, and $(KBUILD_VMLINUX_INIT) must be first.
+# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
+# from top-level directories in the kernel tree, others are specified in
+# arch/$(ARCH)/Makefile. Ordering when linking is important, and
+# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
+# which are linked conditionally (not within --whole-archive), and do not
+# require symbol indexes added.
 #
 # vmlinux
 #   ^
@@ -16,6 +19,9 @@
 #   +--< $(KBUILD_VMLINUX_MAIN)
 #   |    +--< drivers/built-in.o mm/built-in.o + more
 #   |
+#   +--< $(KBUILD_VMLINUX_LIBS)
+#   |    +--< lib/lib.a + more
+#   |
 #   +-< ${kallsymso} (see description in KALLSYMS section)
 #
 # vmlinux version (uname -v) cannot be updated during normal
@@ -37,9 +43,10 @@ info()
 	fi
 }
 
-# Thin archive build here makes a final archive with
-# symbol table and indexes from vmlinux objects, which can be
-# used as input to linker.
+# Thin archive build here makes a final archive with symbol table and indexes
+# from vmlinux objects INIT and MAIN, which can be used as input to linker.
+# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
+# added.
 #
 # Traditional incremental style of link does not require this step
 #
@@ -50,7 +57,7 @@ archive_builtin()
 	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 		info AR built-in.o
 		rm -f built-in.o;
-		${AR} rcsT${KBUILD_ARFLAGS} built-in.o			\
+		${AR} rcsTP${KBUILD_ARFLAGS} built-in.o			\
 					${KBUILD_VMLINUX_INIT}		\
 					${KBUILD_VMLINUX_MAIN}
 	fi
@@ -63,11 +70,17 @@ modpost_link()
 	local objects
 
 	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
-		objects="--whole-archive built-in.o"
+		objects="--whole-archive				\
+			built-in.o					\
+			--no-whole-archive				\
+			--start-group					\
+			${KBUILD_VMLINUX_LIBS}				\
+			--end-group"
 	else
 		objects="${KBUILD_VMLINUX_INIT}				\
 			--start-group					\
 			${KBUILD_VMLINUX_MAIN}				\
+			${KBUILD_VMLINUX_LIBS}				\
 			--end-group"
 	fi
 	${LD} ${LDFLAGS} -r -o ${1} ${objects}
@@ -83,11 +96,18 @@ vmlinux_link()
 
 	if [ "${SRCARCH}" != "um" ]; then
 		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
-			objects="--whole-archive built-in.o ${1}"
+			objects="--whole-archive			\
+				built-in.o				\
+				--no-whole-archive			\
+				--start-group				\
+				${KBUILD_VMLINUX_LIBS}			\
+				--end-group				\
+				${1}"
 		else
 			objects="${KBUILD_VMLINUX_INIT}			\
 				--start-group				\
 				${KBUILD_VMLINUX_MAIN}			\
+				${KBUILD_VMLINUX_LIBS}			\
 				--end-group				\
 				${1}"
 		fi
@@ -96,11 +116,18 @@ vmlinux_link()
 			-T ${lds} ${objects}
 	else
 		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
-			objects="-Wl,--whole-archive built-in.o ${1}"
+			objects="-Wl,--whole-archive			\
+				built-in.o				\
+				-Wl,--no-whole-archive			\
+				-Wl,--start-group			\
+				${KBUILD_VMLINUX_LIBS}			\
+				-Wl,--end-group				\
+				${1}"
 		else
 			objects="${KBUILD_VMLINUX_INIT}			\
 				-Wl,--start-group			\
 				${KBUILD_VMLINUX_MAIN}			\
+				${KBUILD_VMLINUX_LIBS}			\
 				-Wl,--end-group				\
 				${1}"
 		fi