kbuild: use obj-y instead extra-y for objects placed at the head

The objects placed at the head of vmlinux need special treatments:

 - arch/$(SRCARCH)/Makefile adds them to head-y in order to place
   them before other archives in the linker command line.

 - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
   obj-y to avoid them going into built-in.a.

This commit gets rid of the latter.

Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.

With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.

There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.

$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].

[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

23 files changed, 62 insertions, 61 deletions

diff --git a/arch/alpha/kernel/Makefile b/arch/alpha/kernel/Makefile
index 5a74581bf0ee..5a5b0a8b7c6a 100644
--- a/arch/alpha/kernel/Makefile
+++ b/arch/alpha/kernel/Makefile
@@ -3,11 +3,11 @@
 # Makefile for the linux kernel.
 #
 
-extra-y		:= head.o vmlinux.lds
+extra-y		:= vmlinux.lds
 asflags-y	:= $(KBUILD_CFLAGS)
 ccflags-y	:= -Wno-sign-compare
 
-obj-y    := entry.o traps.o process.o osf_sys.o irq.o \
+obj-y    := head.o entry.o traps.o process.o osf_sys.o irq.o \
 	    irq_alpha.o signal.o setup.o ptrace.o time.o \
 	    systbls.o err_common.o io.o bugs.o
 
diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 8c4fc4b54c14..0723d888ac44 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -3,7 +3,7 @@
 # Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 #
 
-obj-y	:= arcksyms.o setup.o irq.o reset.o ptrace.o process.o devtree.o
+obj-y	:= head.o arcksyms.o setup.o irq.o reset.o ptrace.o process.o devtree.o
 obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o disasm.o
 obj-$(CONFIG_ISA_ARCOMPACT)		+= entry-compact.o intc-compact.o
 obj-$(CONFIG_ISA_ARCV2)			+= entry-arcv2.o intc-arcv2.o
@@ -31,4 +31,4 @@ else
 obj-y += ctx_sw_asm.o
 endif
 
-extra-y := vmlinux.lds head.o
+extra-y := vmlinux.lds
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 553866751e1a..8feaa3217ec5 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -89,7 +89,7 @@ obj-$(CONFIG_VDSO)		+= vdso.o
 obj-$(CONFIG_EFI)		+= efi.o
 obj-$(CONFIG_PARAVIRT)	+= paravirt.o
 
-head-y			:= head$(MMUEXT).o
+obj-y			+= head$(MMUEXT).o
 obj-$(CONFIG_DEBUG_LL)	+= debug.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_ARM_PATCH_PHYS_VIRT)	+= phys2virt.o
@@ -109,4 +109,4 @@ obj-$(CONFIG_HAVE_ARM_SMCCC)	+= smccc-call.o
 
 obj-$(CONFIG_GENERIC_CPU_VULNERABILITIES) += spectre.o
 
-extra-y := $(head-y) vmlinux.lds
+extra-y := vmlinux.lds
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 1add7b01efa7..b619ff207a57 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -85,8 +85,8 @@ $(obj)/vdso-wrap.o: $(obj)/vdso/vdso.so
 $(obj)/vdso32-wrap.o: $(obj)/vdso32/vdso.so
 
 obj-y					+= probes/
-head-y					:= head.o
-extra-y					+= $(head-y) vmlinux.lds
+obj-y					+= head.o
+extra-y					+= vmlinux.lds
 
 ifeq ($(CONFIG_DEBUG_EFI),y)
 AFLAGS_head.o += -DVMLINUX_PATH="\"$(realpath $(objtree)/vmlinux)\""
diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index 6f14c924b20d..8a868316b912 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
-extra-y := head.o vmlinux.lds
+extra-y := vmlinux.lds
 
-obj-y += entry.o atomic.o signal.o traps.o irq.o time.o vdso.o vdso/
+obj-y += head.o entry.o atomic.o signal.o traps.o irq.o time.o vdso.o vdso/
 obj-y += power.o syscall.o syscall_table.o setup.o io.o
 obj-y += process.o cpu-probe.o ptrace.o stacktrace.o
 obj-y += probes/
diff --git a/arch/hexagon/kernel/Makefile b/arch/hexagon/kernel/Makefile
index fae3dce32fde..e73cb321630e 100644
--- a/arch/hexagon/kernel/Makefile
+++ b/arch/hexagon/kernel/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
-extra-y := head.o vmlinux.lds
+extra-y := vmlinux.lds
 
+obj-y += head.o
 obj-$(CONFIG_SMP) += smp.o
 
 obj-y += setup.o irq_cpu.o traps.o syscalltab.o signal.o time.o
diff --git a/arch/ia64/kernel/Makefile b/arch/ia64/kernel/Makefile
index 08d4a2ba0652..4a1fcb121dda 100644
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -7,9 +7,9 @@ ifdef CONFIG_DYNAMIC_FTRACE
 CFLAGS_REMOVE_ftrace.o = -pg
 endif
 
-extra-y	:= head.o vmlinux.lds
+extra-y	:= vmlinux.lds
 
-obj-y := entry.o efi.o efi_stub.o gate-data.o fsys.o irq.o irq_ia64.o	\
+obj-y := head.o entry.o efi.o efi_stub.o gate-data.o fsys.o irq.o irq_ia64.o	\
 	 irq_lsapic.o ivt.o pal.o patch.o process.o ptrace.o sal.o		\
 	 salinfo.o setup.o signal.o sys_ia64.o time.o traps.o unaligned.o \
 	 unwind.o mca.o mca_asm.o topology.o dma-mapping.o iosapic.o acpi.o \
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index e5be17009fe8..6c33b5c45573 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for the Linux/LoongArch kernel.
 #
 
-extra-y		:= head.o vmlinux.lds
+extra-y		:= vmlinux.lds
 
-obj-y		+= cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
+obj-y		+= head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
 		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
 		   elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o
 
diff --git a/arch/m68k/68000/Makefile b/arch/m68k/68000/Makefile
index 674541fdf5b8..279560add577 100644
--- a/arch/m68k/68000/Makefile
+++ b/arch/m68k/68000/Makefile
@@ -17,4 +17,4 @@ obj-$(CONFIG_DRAGEN2)	+= dragen2.o
 obj-$(CONFIG_UCSIMM)	+= ucsimm.o
 obj-$(CONFIG_UCDIMM)	+= ucsimm.o
 
-extra-y 		:= head.o
+obj-y			+= head.o
diff --git a/arch/m68k/coldfire/Makefile b/arch/m68k/coldfire/Makefile
index 9419a6c1f036..c56bc0dc7f2e 100644
--- a/arch/m68k/coldfire/Makefile
+++ b/arch/m68k/coldfire/Makefile
@@ -45,4 +45,4 @@ obj-$(CONFIG_STMARK2)	+= stmark2.o
 obj-$(CONFIG_PCI)	+= pci.o
 
 obj-y			+= gpio.o
-extra-y := head.o
+obj-y			+= head.o
diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index c0833da6a2ca..af015447dfb4 100644
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -3,19 +3,20 @@
 # Makefile for the linux kernel.
 #
 
-extra-$(CONFIG_AMIGA)	:= head.o
-extra-$(CONFIG_ATARI)	:= head.o
-extra-$(CONFIG_MAC)	:= head.o
-extra-$(CONFIG_APOLLO)	:= head.o
-extra-$(CONFIG_VME)	:= head.o
-extra-$(CONFIG_HP300)	:= head.o
-extra-$(CONFIG_Q40)	:= head.o
-extra-$(CONFIG_SUN3X)	:= head.o
-extra-$(CONFIG_VIRT)	:= head.o
-extra-$(CONFIG_SUN3)	:= sun3-head.o
 extra-y			+= vmlinux.lds
 
-obj-y	:= entry.o irq.o module.o process.o ptrace.o
+obj-$(CONFIG_AMIGA)	:= head.o
+obj-$(CONFIG_ATARI)	:= head.o
+obj-$(CONFIG_MAC)	:= head.o
+obj-$(CONFIG_APOLLO)	:= head.o
+obj-$(CONFIG_VME)	:= head.o
+obj-$(CONFIG_HP300)	:= head.o
+obj-$(CONFIG_Q40)	:= head.o
+obj-$(CONFIG_SUN3X)	:= head.o
+obj-$(CONFIG_VIRT)	:= head.o
+obj-$(CONFIG_SUN3)	:= sun3-head.o
+
+obj-y	+= entry.o irq.o module.o process.o ptrace.o
 obj-y	+= setup.o signal.o sys_m68k.o syscalltable.o time.o traps.o
 
 obj-$(CONFIG_MMU_MOTOROLA) += ints.o vectors.o
diff --git a/arch/microblaze/kernel/Makefile b/arch/microblaze/kernel/Makefile
index 15a20eb814ce..4393bee64eaf 100644
--- a/arch/microblaze/kernel/Makefile
+++ b/arch/microblaze/kernel/Makefile
@@ -12,9 +12,9 @@ CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_process.o = -pg
 endif
 
-extra-y := head.o vmlinux.lds
+extra-y := vmlinux.lds
 
-obj-y += dma.o exceptions.o \
+obj-y += head.o dma.o exceptions.o \
 	hw_exception_handler.o irq.o \
 	process.o prom.o ptrace.o \
 	reset.o setup.o signal.o sys_microblaze.o timer.o traps.o unwind.o
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 7c96282bff2e..5d1addac5e28 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for the Linux/MIPS kernel.
 #
 
-extra-y		:= head.o vmlinux.lds
+extra-y		:= vmlinux.lds
 
-obj-y		+= branch.o cmpxchg.o elf.o entry.o genex.o idle.o irq.o \
+obj-y		+= head.o branch.o cmpxchg.o elf.o entry.o genex.o idle.o irq.o \
 		   process.o prom.o ptrace.o reset.o setup.o signal.o \
 		   syscall.o time.o topology.o traps.o unaligned.o watch.o \
 		   vdso.o cacheinfo.o
diff --git a/arch/nios2/kernel/Makefile b/arch/nios2/kernel/Makefile
index 0b645e1e3158..78a913181fa1 100644
--- a/arch/nios2/kernel/Makefile
+++ b/arch/nios2/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for the nios2 linux kernel.
 #
 
-extra-y	+= head.o
 extra-y	+= vmlinux.lds
 
+obj-y	+= head.o
 obj-y	+= cpuinfo.o
 obj-y	+= entry.o
 obj-y	+= insnemu.o
diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
index 2d172e79f58d..79129161f3e0 100644
--- a/arch/openrisc/kernel/Makefile
+++ b/arch/openrisc/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for the linux kernel.
 #
 
-extra-y	:= head.o vmlinux.lds
+extra-y	:= vmlinux.lds
 
-obj-y	:= setup.o or32_ksyms.o process.o dma.o \
+obj-y	:= head.o setup.o or32_ksyms.o process.o dma.o \
 	   traps.o time.o irq.o entry.o ptrace.o signal.o \
 	   sys_call_table.o unwinder.o
 
diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index d0bfac89a842..3d138c9cf9ce 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for arch/parisc/kernel
 #
 
-extra-y			:= head.o vmlinux.lds
+extra-y		:= vmlinux.lds
 
-obj-y	     	:= cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
+obj-y		:= head.o cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
 		   pa7300lc.o syscall.o entry.o sys_parisc.o firmware.o \
 		   ptrace.o hardware.o inventory.o drivers.o alternative.o \
 		   signal.o hpmc.o real2.o parisc_ksyms.o unaligned.o \
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 06d2d1f78f71..ad3decb9f20b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -118,12 +118,12 @@ obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o
 obj-$(CONFIG_PPC_DOORBELL)	+= dbell.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
-extra-$(CONFIG_PPC64)		:= head_64.o
-extra-$(CONFIG_PPC_BOOK3S_32)	:= head_book3s_32.o
-extra-$(CONFIG_40x)		:= head_40x.o
-extra-$(CONFIG_44x)		:= head_44x.o
-extra-$(CONFIG_FSL_BOOKE)	:= head_fsl_booke.o
-extra-$(CONFIG_PPC_8xx)		:= head_8xx.o
+obj-$(CONFIG_PPC64)		+= head_64.o
+obj-$(CONFIG_PPC_BOOK3S_32)	+= head_book3s_32.o
+obj-$(CONFIG_40x)		+= head_40x.o
+obj-$(CONFIG_44x)		+= head_44x.o
+obj-$(CONFIG_FSL_BOOKE)		+= head_fsl_booke.o
+obj-$(CONFIG_PPC_8xx)		+= head_8xx.o
 extra-y				+= vmlinux.lds
 
 obj-$(CONFIG_RELOCATABLE)	+= reloc_$(BITS).o
@@ -198,10 +198,10 @@ KCOV_INSTRUMENT_paca.o := n
 CFLAGS_setup_64.o		+= -fno-stack-protector
 CFLAGS_paca.o			+= -fno-stack-protector
 
-extra-$(CONFIG_PPC_FPU)		+= fpu.o
-extra-$(CONFIG_ALTIVEC)		+= vector.o
-extra-$(CONFIG_PPC64)		+= entry_64.o
-extra-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE)	+= prom_init.o
+obj-$(CONFIG_PPC_FPU)		+= fpu.o
+obj-$(CONFIG_ALTIVEC)		+= vector.o
+obj-$(CONFIG_PPC64)		+= entry_64.o
+obj-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE)	+= prom_init.o
 
 extra-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE)	+= prom_init_check
 
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 33bb60a354cd..db6e4b1294ba 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -28,9 +28,9 @@ KASAN_SANITIZE_cpufeature.o := n
 endif
 endif
 
-extra-y += head.o
 extra-y += vmlinux.lds
 
+obj-y	+= head.o
 obj-y	+= soc.o
 obj-$(CONFIG_RISCV_ALTERNATIVE) += alternative.o
 obj-y	+= cpu.o
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 3cbfa9fddd9a..7ce00816b8df 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -33,7 +33,7 @@ CFLAGS_stacktrace.o	+= -fno-optimize-sibling-calls
 CFLAGS_dumpstack.o	+= -fno-optimize-sibling-calls
 CFLAGS_unwind_bc.o	+= -fno-optimize-sibling-calls
 
-obj-y	:= traps.o time.o process.o earlypgm.o early.o setup.o idle.o vtime.o
+obj-y	:= head64.o traps.o time.o process.o earlypgm.o early.o setup.o idle.o vtime.o
 obj-y	+= processor.o syscall.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
 obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o cpufeature.o
 obj-y	+= sysinfo.o lgr.o os_info.o machine_kexec.o
@@ -42,7 +42,7 @@ obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
 obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o
 obj-y	+= smp.o text_amode31.o stacktrace.o
 
-extra-y				+= head64.o vmlinux.lds
+extra-y				+= vmlinux.lds
 
 obj-$(CONFIG_SYSFS)		+= nospec-sysfs.o
 CFLAGS_REMOVE_nospec-branch.o	+= $(CC_FLAGS_EXPOLINE)
diff --git a/arch/sh/kernel/Makefile b/arch/sh/kernel/Makefile
index aa0fbc9202b1..69cd9ac4b2ab 100644
--- a/arch/sh/kernel/Makefile
+++ b/arch/sh/kernel/Makefile
@@ -3,7 +3,7 @@
 # Makefile for the Linux/SuperH kernel.
 #
 
-extra-y	:= head_32.o vmlinux.lds
+extra-y	:= vmlinux.lds
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities
@@ -12,7 +12,7 @@ endif
 
 CFLAGS_REMOVE_return_address.o = -pg
 
-obj-y	:= debugtraps.o dumpstack.o 		\
+obj-y	:= head_32.o debugtraps.o dumpstack.o				\
 	   idle.o io.o irq.o irq_32.o kdebugfs.o			\
 	   machvec.o nmi_debug.o process.o				\
 	   process_32.o ptrace.o ptrace_32.o				\
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
index d3a0e072ebe8..b328e4a0bd57 100644
--- a/arch/sparc/kernel/Makefile
+++ b/arch/sparc/kernel/Makefile
@@ -7,8 +7,6 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-extra-y     := head_$(BITS).o
-
 # Undefine sparc when processing vmlinux.lds - it is used
 # And teach CPP we are doing $(BITS) builds (for this case)
 CPPFLAGS_vmlinux.lds := -Usparc -m$(BITS)
@@ -22,6 +20,7 @@ CFLAGS_REMOVE_perf_event.o := -pg
 CFLAGS_REMOVE_pcr.o := -pg
 endif
 
+obj-y                   := head_$(BITS).o
 obj-$(CONFIG_SPARC64)   += urtt_fill.o
 obj-$(CONFIG_SPARC32)   += entry.o wof.o wuf.o
 obj-$(CONFIG_SPARC32)   += etrap_32.o
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a20a5ebfacd7..956e50ca06e0 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -3,10 +3,6 @@
 # Makefile for the linux kernel.
 #
 
-extra-y	:= head_$(BITS).o
-extra-y	+= head$(BITS).o
-extra-y	+= ebda.o
-extra-y	+= platform-quirks.o
 extra-y	+= vmlinux.lds
 
 CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE)
@@ -42,7 +38,11 @@ KCOV_INSTRUMENT		:= n
 
 CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
 
-obj-y			:= process_$(BITS).o signal.o
+obj-y			+= head_$(BITS).o
+obj-y			+= head$(BITS).o
+obj-y			+= ebda.o
+obj-y			+= platform-quirks.o
+obj-y			+= process_$(BITS).o signal.o
 obj-$(CONFIG_COMPAT)	+= signal_compat.o
 obj-y			+= traps.o idt.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
 obj-y			+= time.o ioport.o dumpstack.o nmi.o
diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile
index 897c1c741058..f28b8e3d717e 100644
--- a/arch/xtensa/kernel/Makefile
+++ b/arch/xtensa/kernel/Makefile
@@ -3,9 +3,9 @@
 # Makefile for the Linux/Xtensa kernel.
 #
 
-extra-y := head.o vmlinux.lds
+extra-y := vmlinux.lds
 
-obj-y := align.o coprocessor.o entry.o irq.o platform.o process.o \
+obj-y := head.o align.o coprocessor.o entry.o irq.o platform.o process.o \
 	 ptrace.o setup.o signal.o stacktrace.o syscall.o time.o traps.o \
 	 vectors.o