diff options
author | Masahiro Yamada <masahiroy@kernel.org> | 2022-09-24 21:19:15 +0300 |
---|---|---|
committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-10-02 12:06:03 +0300 |
commit | ce697ccee1a8661da4e23fbe5f3d45d8d6922c20 (patch) | |
tree | 3e4a66982f38b33d4c17b13a04161eb764bf6220 | |
parent | 3216484550610470013b7ce1c9ed272da0a74589 (diff) | |
download | linux-ce697ccee1a8661da4e23fbe5f3d45d8d6922c20.tar.xz |
kbuild: remove head-y syntax
Kbuild puts the objects listed in head-y at the head of vmlinux.
Conventionally, we do this for head*.S, which contains the kernel entry
point.
A counter approach is to control the section order by the linker script.
Actually, the code marked as __HEAD goes into the ".head.text" section,
which is placed before the normal ".text" section.
I do not know if both of them are needed. From the build system
perspective, head-y is not mandatory. If you can achieve the proper code
placement by the linker script only, it would be cleaner.
I collected the current head-y objects into head-object-list.txt. It is
a whitelist. My hope is it will be reduced in the long run.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
-rw-r--r-- | Documentation/kbuild/makefiles.rst | 9 | ||||
-rw-r--r-- | Makefile | 4 | ||||
-rw-r--r-- | arch/alpha/Makefile | 2 | ||||
-rw-r--r-- | arch/arc/Makefile | 2 | ||||
-rw-r--r-- | arch/arm/Makefile | 3 | ||||
-rw-r--r-- | arch/arm64/Makefile | 3 | ||||
-rw-r--r-- | arch/csky/Makefile | 2 | ||||
-rw-r--r-- | arch/hexagon/Makefile | 2 | ||||
-rw-r--r-- | arch/ia64/Makefile | 1 | ||||
-rw-r--r-- | arch/loongarch/Makefile | 2 | ||||
-rw-r--r-- | arch/m68k/Makefile | 9 | ||||
-rw-r--r-- | arch/microblaze/Makefile | 1 | ||||
-rw-r--r-- | arch/mips/Makefile | 2 | ||||
-rw-r--r-- | arch/nios2/Makefile | 1 | ||||
-rw-r--r-- | arch/openrisc/Makefile | 2 | ||||
-rw-r--r-- | arch/parisc/Makefile | 2 | ||||
-rw-r--r-- | arch/powerpc/Makefile | 12 | ||||
-rw-r--r-- | arch/riscv/Makefile | 2 | ||||
-rw-r--r-- | arch/s390/Makefile | 2 | ||||
-rw-r--r-- | arch/sh/Makefile | 2 | ||||
-rw-r--r-- | arch/sparc/Makefile | 2 | ||||
-rw-r--r-- | arch/x86/Makefile | 5 | ||||
-rw-r--r-- | arch/xtensa/Makefile | 2 | ||||
-rw-r--r-- | scripts/head-object-list.txt | 53 |
24 files changed, 60 insertions, 67 deletions
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 5a6a8426cc97..60134ddf3db1 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -1070,8 +1070,7 @@ When kbuild executes, the following steps are followed (roughly): - The values of the above variables are expanded in arch/$(SRCARCH)/Makefile. 5) All object files are then linked and the resulting file vmlinux is located at the root of the obj tree. - The very first objects linked are listed in head-y, assigned by - arch/$(SRCARCH)/Makefile. + The very first objects linked are listed in scripts/head-object-list.txt. 6) Finally, the architecture-specific part does any required post processing and builds the final bootimage. - This includes building boot records @@ -1219,6 +1218,9 @@ When kbuild executes, the following steps are followed (roughly): All object files for vmlinux. They are linked to vmlinux in the same order as listed in KBUILD_VMLINUX_OBJS. + The objects listed in scripts/head-object-list.txt are exceptions; + they are placed before the other objects. + KBUILD_VMLINUX_LIBS All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and @@ -1262,8 +1264,7 @@ When kbuild executes, the following steps are followed (roughly): machinery is all architecture-independent. - head-y, core-y, libs-y, drivers-y - $(head-y) lists objects to be linked first in vmlinux. + core-y, libs-y, drivers-y $(libs-y) lists directories where a lib.a archive can be located. @@ -1147,10 +1147,10 @@ quiet_cmd_ar_vmlinux.a = AR $@ cmd_ar_vmlinux.a = \ rm -f $@; \ $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \ - $(AR) mPiT $$($(AR) t $@ | head -n1) $@ $(head-y) + $(AR) mPiT $$($(AR) t $@ | head -n1) $@ $$($(AR) t $@ | grep -F --file=$(srctree)/scripts/head-object-list.txt) targets += vmlinux.a -vmlinux.a: $(KBUILD_VMLINUX_OBJS) autoksyms_recursive FORCE +vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt autoksyms_recursive FORCE $(call if_changed,ar_vmlinux.a) vmlinux.o: vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile index 881cb913e23a..45158024085e 100644 --- a/arch/alpha/Makefile +++ b/arch/alpha/Makefile @@ -36,8 +36,6 @@ cflags-y += $(cpuflags-y) # BWX is most important, but we don't really want any emulation ever. KBUILD_CFLAGS += $(cflags-y) -Wa,-mev6 -head-y := arch/alpha/kernel/head.o - libs-y += arch/alpha/lib/ # export what is needed by arch/alpha/boot/Makefile diff --git a/arch/arc/Makefile b/arch/arc/Makefile index efc54f3e35e0..329400a1c355 100644 --- a/arch/arc/Makefile +++ b/arch/arc/Makefile @@ -82,8 +82,6 @@ KBUILD_CFLAGS += $(cflags-y) KBUILD_AFLAGS += $(KBUILD_CFLAGS) KBUILD_LDFLAGS += $(ldflags-y) -head-y := arch/arc/kernel/head.o - # w/o this dtb won't embed into kernel binary core-y += arch/arc/boot/dts/ diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 56f655deebb1..29d15c9a433e 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -134,9 +134,6 @@ KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/uni CHECKFLAGS += -D__arm__ -#Default value -head-y := arch/arm/kernel/head$(MMUEXT).o - # Text offset. This list is sorted numerically by address in order to # provide a means to avoid/resolve conflicts in multi-arch kernels. # Note: the 32kB below this value is reserved for use by the kernel diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 6d9d4a58b898..6e03f15bb041 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -133,9 +133,6 @@ ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y) CC_FLAGS_FTRACE := -fpatchable-function-entry=2 endif -# Default value -head-y := arch/arm64/kernel/head.o - ifeq ($(CONFIG_KASAN_SW_TAGS), y) KASAN_SHADOW_SCALE_SHIFT := 4 else ifeq ($(CONFIG_KASAN_GENERIC), y) diff --git a/arch/csky/Makefile b/arch/csky/Makefile index 4e1d619fd5c6..0e4237e55758 100644 --- a/arch/csky/Makefile +++ b/arch/csky/Makefile @@ -59,8 +59,6 @@ LDFLAGS += -EL KBUILD_AFLAGS += $(KBUILD_CFLAGS) -head-y := arch/csky/kernel/head.o - core-y += arch/csky/$(CSKYABI)/ libs-y += arch/csky/lib/ \ diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile index 44312bc147d8..92d005958dfb 100644 --- a/arch/hexagon/Makefile +++ b/arch/hexagon/Makefile @@ -32,5 +32,3 @@ KBUILD_LDFLAGS += $(ldflags-y) TIR_NAME := r19 KBUILD_CFLAGS += -ffixed-$(TIR_NAME) -DTHREADINFO_REG=$(TIR_NAME) -D__linux__ KBUILD_AFLAGS += -DTHREADINFO_REG=$(TIR_NAME) - -head-y := arch/hexagon/kernel/head.o diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile index e55c2f138656..56c4bb276b6e 100644 --- a/arch/ia64/Makefile +++ b/arch/ia64/Makefile @@ -44,7 +44,6 @@ quiet_cmd_objcopy = OBJCOPY $@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@ KBUILD_CFLAGS += $(cflags-y) -head-y := arch/ia64/kernel/head.o libs-y += arch/ia64/lib/ diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index ec3de6191276..131fc210c2bf 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -72,8 +72,6 @@ CHECKFLAGS += $(shell $(CC) $(KBUILD_CFLAGS) -dM -E -x c /dev/null | \ sed -e "s/^\#define /-D'/" -e "s/ /'='/" -e "s/$$/'/" -e 's/\$$/&&/g') endif -head-y := arch/loongarch/kernel/head.o - libs-y += arch/loongarch/lib/ ifeq ($(KBUILD_EXTMOD),) diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile index e358605b70ba..43e39040d3ac 100644 --- a/arch/m68k/Makefile +++ b/arch/m68k/Makefile @@ -86,15 +86,6 @@ ifdef CONFIG_KGDB KBUILD_CFLAGS := $(subst -fomit-frame-pointer,,$(KBUILD_CFLAGS)) -g endif -# -# Select the assembler head startup code. Order is important. The default -# head code is first, processor specific selections can override it after. -# -head-y := arch/m68k/kernel/head.o -head-$(CONFIG_SUN3) := arch/m68k/kernel/sun3-head.o -head-$(CONFIG_M68000) := arch/m68k/68000/head.o -head-$(CONFIG_COLDFIRE) := arch/m68k/coldfire/head.o - libs-y += arch/m68k/lib/ diff --git a/arch/microblaze/Makefile b/arch/microblaze/Makefile index 1826d9ce4459..3f8a86c4336a 100644 --- a/arch/microblaze/Makefile +++ b/arch/microblaze/Makefile @@ -48,7 +48,6 @@ CPUFLAGS-1 += $(call cc-option,-mcpu=v$(CPU_VER)) # r31 holds current when in kernel mode KBUILD_CFLAGS += -ffixed-r31 $(CPUFLAGS-y) $(CPUFLAGS-1) $(CPUFLAGS-2) -head-y := arch/microblaze/kernel/head.o libs-y += arch/microblaze/lib/ boot := arch/microblaze/boot diff --git a/arch/mips/Makefile b/arch/mips/Makefile index 4d2a3e73fc45..b296e33f8e33 100644 --- a/arch/mips/Makefile +++ b/arch/mips/Makefile @@ -324,8 +324,6 @@ endif OBJCOPYFLAGS += --remove-section=.reginfo -head-y := arch/mips/kernel/head.o - libs-y += arch/mips/lib/ libs-$(CONFIG_MIPS_FP_SUPPORT) += arch/mips/math-emu/ diff --git a/arch/nios2/Makefile b/arch/nios2/Makefile index 3f34e6831863..f1ff4ce0f1a2 100644 --- a/arch/nios2/Makefile +++ b/arch/nios2/Makefile @@ -37,7 +37,6 @@ KBUILD_CFLAGS += -DUTS_SYSNAME=\"$(UTS_SYSNAME)\" KBUILD_CFLAGS += -fno-builtin KBUILD_CFLAGS += -G 0 -head-y := arch/nios2/kernel/head.o libs-y += arch/nios2/lib/ $(LIBGCC) INSTALL_PATH ?= /tftpboot diff --git a/arch/openrisc/Makefile b/arch/openrisc/Makefile index b446510173cd..68249521db5a 100644 --- a/arch/openrisc/Makefile +++ b/arch/openrisc/Makefile @@ -55,8 +55,6 @@ ifeq ($(CONFIG_OPENRISC_HAVE_INST_SEXT),y) KBUILD_CFLAGS += $(call cc-option,-msext) endif -head-y := arch/openrisc/kernel/head.o - libs-y += $(LIBGCC) PHONY += vmlinux.bin diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile index e38d993d87f2..a2d8600521f9 100644 --- a/arch/parisc/Makefile +++ b/arch/parisc/Makefile @@ -113,8 +113,6 @@ cflags-$(CONFIG_PA7100LC) += -march=1.1 -mschedule=7100LC cflags-$(CONFIG_PA7300LC) += -march=1.1 -mschedule=7300 cflags-$(CONFIG_PA8X00) += -march=2.0 -mschedule=8000 -head-y := arch/parisc/kernel/head.o - KBUILD_CFLAGS += $(cflags-y) LIBGCC := $(shell $(CC) -print-libgcc-file-name) export LIBGCC diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 02742facf895..89c27827a11f 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -226,18 +226,6 @@ KBUILD_CFLAGS += $(cpu-as-y) KBUILD_AFLAGS += $(aflags-y) KBUILD_CFLAGS += $(cflags-y) -head-$(CONFIG_PPC64) := arch/powerpc/kernel/head_64.o -head-$(CONFIG_PPC_BOOK3S_32) := arch/powerpc/kernel/head_book3s_32.o -head-$(CONFIG_PPC_8xx) := arch/powerpc/kernel/head_8xx.o -head-$(CONFIG_40x) := arch/powerpc/kernel/head_40x.o -head-$(CONFIG_44x) := arch/powerpc/kernel/head_44x.o -head-$(CONFIG_FSL_BOOKE) := arch/powerpc/kernel/head_fsl_booke.o - -head-$(CONFIG_PPC64) += arch/powerpc/kernel/entry_64.o -head-$(CONFIG_PPC_FPU) += arch/powerpc/kernel/fpu.o -head-$(CONFIG_ALTIVEC) += arch/powerpc/kernel/vector.o -head-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE) += arch/powerpc/kernel/prom_init.o - # Default to zImage, override when needed all: zImage diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 3fa8ef336822..e013df8e7b8b 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -110,8 +110,6 @@ else KBUILD_IMAGE := $(boot)/Image.gz endif -head-y := arch/riscv/kernel/head.o - libs-y += arch/riscv/lib/ libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a diff --git a/arch/s390/Makefile b/arch/s390/Makefile index 4cb5d17e7ead..de6d8b2ea4d8 100644 --- a/arch/s390/Makefile +++ b/arch/s390/Makefile @@ -119,8 +119,6 @@ export KBUILD_CFLAGS_DECOMPRESSOR OBJCOPYFLAGS := -O binary -head-y := arch/s390/kernel/head64.o - libs-y += arch/s390/lib/ drivers-y += drivers/s390/ diff --git a/arch/sh/Makefile b/arch/sh/Makefile index b39412bf91fb..5c8776482530 100644 --- a/arch/sh/Makefile +++ b/arch/sh/Makefile @@ -114,8 +114,6 @@ endif export ld-bfd -head-y := arch/sh/kernel/head_32.o - # Mach groups machdir-$(CONFIG_SOLUTION_ENGINE) += mach-se machdir-$(CONFIG_SH_HP6XX) += mach-hp6xx diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile index fe58a410b4ce..a4ea5b05f288 100644 --- a/arch/sparc/Makefile +++ b/arch/sparc/Makefile @@ -56,8 +56,6 @@ endif endif -head-y := arch/sparc/kernel/head_$(BITS).o - libs-y += arch/sparc/prom/ libs-y += arch/sparc/lib/ diff --git a/arch/x86/Makefile b/arch/x86/Makefile index bafbd905e6e7..9afd323c6916 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -234,11 +234,6 @@ archheaders: ### # Kernel objects -head-y := arch/x86/kernel/head_$(BITS).o -head-y += arch/x86/kernel/head$(BITS).o -head-y += arch/x86/kernel/ebda.o -head-y += arch/x86/kernel/platform-quirks.o - libs-y += arch/x86/lib/ # drivers-y are linked after core-y diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile index 5097caa7bf0c..bfd8e433ed62 100644 --- a/arch/xtensa/Makefile +++ b/arch/xtensa/Makefile @@ -55,8 +55,6 @@ KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(vardirs) $(plfdirs)) KBUILD_DEFCONFIG := iss_defconfig -head-y := arch/xtensa/kernel/head.o - libs-y += arch/xtensa/lib/ boot := arch/xtensa/boot diff --git a/scripts/head-object-list.txt b/scripts/head-object-list.txt new file mode 100644 index 000000000000..dd2ba2eda636 --- /dev/null +++ b/scripts/head-object-list.txt @@ -0,0 +1,53 @@ +# Head objects +# +# The objects listed here are placed at the head of vmlinux. A typical use-case +# is an object that contains the entry point. This is kept for compatibility +# with head-y, which Kbuild used to support. +# +# A counter approach is to control the section placement by the linker script. +# The code marked as __HEAD goes into the ".head.text" section, which is placed +# before the normal ".text" section. +# +# If you can achieve the correct code ordering by linker script, please delete +# the entry from this file. +# +arch/alpha/kernel/head.o +arch/arc/kernel/head.o +arch/arm/kernel/head-nommu.o +arch/arm/kernel/head.o +arch/arm64/kernel/head.o +arch/csky/kernel/head.o +arch/hexagon/kernel/head.o +arch/ia64/kernel/head.o +arch/loongarch/kernel/head.o +arch/m68k/68000/head.o +arch/m68k/coldfire/head.o +arch/m68k/kernel/head.o +arch/m68k/kernel/sun3-head.o +arch/microblaze/kernel/head.o +arch/mips/kernel/head.o +arch/nios2/kernel/head.o +arch/openrisc/kernel/head.o +arch/parisc/kernel/head.o +arch/powerpc/kernel/head_40x.o +arch/powerpc/kernel/head_44x.o +arch/powerpc/kernel/head_64.o +arch/powerpc/kernel/head_8xx.o +arch/powerpc/kernel/head_book3s_32.o +arch/powerpc/kernel/head_fsl_booke.o +arch/powerpc/kernel/entry_64.o +arch/powerpc/kernel/fpu.o +arch/powerpc/kernel/vector.o +arch/powerpc/kernel/prom_init.o +arch/riscv/kernel/head.o +arch/s390/kernel/head64.o +arch/sh/kernel/head_32.o +arch/sparc/kernel/head_32.o +arch/sparc/kernel/head_64.o +arch/x86/kernel/head_32.o +arch/x86/kernel/head_64.o +arch/x86/kernel/head32.o +arch/x86/kernel/head64.o +arch/x86/kernel/ebda.o +arch/x86/kernel/platform-quirks.o +arch/xtensa/kernel/head.o |