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With GNU binutils 2.35+, linking with BFD produces warnings for vmlinux: aarch64-linux-gnu-ld: warning: -z norelro ignored BFD can produce this warning when the target emulation mode does not support RELRO program headers, and -z relro or -z norelro is passed. Alan Modra clarifies: The default linker emulation for an aarch64-linux ld.bfd is -maarch64linux, the default for an aarch64-elf linker is -maarch64elf. They are not equivalent. If you choose -maarch64elf you get an emulation that doesn't support -z relro. The ARCH=arm64 kernel prefers -maarch64elf, but may fall back to -maarch64linux based on the toolchain configuration. LLD will always create RELRO program header regardless of target emulation. To avoid the above warning when linking with BFD, pass -z norelro only when linking with LLD or with -maarch64linux. Fixes:3b92fa7485("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") Fixes:3bbd3db864("arm64: relocatable: fix inconsistencies in linker script and options") Cc: <stable@vger.kernel.org> # 5.0.x- Reported-by: kernelci.org bot <bot@kernelci.org> Reported-by: Quentin Perret <qperret@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Cc: Alan Modra <amodra@gmail.com> Cc: Fāng-ruì Sòng <maskray@google.com> Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
206 lines
6.7 KiB
Makefile
206 lines
6.7 KiB
Makefile
#
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# arch/arm64/Makefile
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#
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# This file is included by the global makefile so that you can add your own
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# architecture-specific flags and dependencies.
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#
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# This file is subject to the terms and conditions of the GNU General Public
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# License. See the file "COPYING" in the main directory of this archive
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# for more details.
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#
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# Copyright (C) 1995-2001 by Russell King
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LDFLAGS_vmlinux :=--no-undefined -X
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ifeq ($(CONFIG_RELOCATABLE), y)
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# Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
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# for relative relocs, since this leads to better Image compression
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# with the relocation offsets always being zero.
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LDFLAGS_vmlinux += -shared -Bsymbolic -z notext \
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$(call ld-option, --no-apply-dynamic-relocs)
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endif
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ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
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ifeq ($(call ld-option, --fix-cortex-a53-843419),)
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$(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
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else
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LDFLAGS_vmlinux += --fix-cortex-a53-843419
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endif
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endif
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ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS), y)
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ifneq ($(CONFIG_ARM64_LSE_ATOMICS), y)
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$(warning LSE atomics not supported by binutils)
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endif
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endif
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cc_has_k_constraint := $(call try-run,echo \
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'int main(void) { \
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asm volatile("and w0, w0, %w0" :: "K" (4294967295)); \
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return 0; \
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}' | $(CC) -S -x c -o "$$TMP" -,,-DCONFIG_CC_HAS_K_CONSTRAINT=1)
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ifeq ($(CONFIG_BROKEN_GAS_INST),y)
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$(warning Detected assembler with broken .inst; disassembly will be unreliable)
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endif
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KBUILD_CFLAGS += -mgeneral-regs-only \
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$(compat_vdso) $(cc_has_k_constraint)
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KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
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KBUILD_AFLAGS += $(compat_vdso)
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KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
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KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
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# Avoid generating .eh_frame* sections.
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
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KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
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ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
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prepare: stack_protector_prepare
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stack_protector_prepare: prepare0
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$(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg \
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-mstack-protector-guard-reg=sp_el0 \
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-mstack-protector-guard-offset=$(shell \
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awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
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include/generated/asm-offsets.h))
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endif
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# Ensure that if the compiler supports branch protection we default it
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# off, this will be overridden if we are using branch protection.
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branch-prot-flags-y += $(call cc-option,-mbranch-protection=none)
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ifeq ($(CONFIG_ARM64_PTR_AUTH),y)
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branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all
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# We enable additional protection for leaf functions as there is some
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# narrow potential for ROP protection benefits and no substantial
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# performance impact has been observed.
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ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
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branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protection=pac-ret+leaf+bti
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else
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branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf
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endif
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# -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the
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# compiler to generate them and consequently to break the single image contract
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# we pass it only to the assembler. This option is utilized only in case of non
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# integrated assemblers.
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ifeq ($(CONFIG_AS_HAS_PAC), y)
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asm-arch := armv8.3-a
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endif
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endif
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KBUILD_CFLAGS += $(branch-prot-flags-y)
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ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
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# make sure to pass the newest target architecture to -march.
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asm-arch := armv8.4-a
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endif
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ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
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# make sure to pass the newest target architecture to -march.
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asm-arch := armv8.5-a
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endif
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ifdef asm-arch
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KBUILD_CFLAGS += -Wa,-march=$(asm-arch) \
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-DARM64_ASM_ARCH='"$(asm-arch)"'
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endif
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ifeq ($(CONFIG_SHADOW_CALL_STACK), y)
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KBUILD_CFLAGS += -ffixed-x18
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endif
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ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
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KBUILD_CPPFLAGS += -mbig-endian
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CHECKFLAGS += -D__AARCH64EB__
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# Prefer the baremetal ELF build target, but not all toolchains include
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# it so fall back to the standard linux version if needed.
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KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb -z norelro)
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UTS_MACHINE := aarch64_be
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else
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KBUILD_CPPFLAGS += -mlittle-endian
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CHECKFLAGS += -D__AARCH64EL__
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# Same as above, prefer ELF but fall back to linux target if needed.
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KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro)
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UTS_MACHINE := aarch64
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endif
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ifeq ($(CONFIG_LD_IS_LLD), y)
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KBUILD_LDFLAGS += -z norelro
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endif
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CHECKFLAGS += -D__aarch64__
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ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
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KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
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CC_FLAGS_FTRACE := -fpatchable-function-entry=2
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endif
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# Default value
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head-y := arch/arm64/kernel/head.o
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ifeq ($(CONFIG_KASAN_SW_TAGS), y)
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KASAN_SHADOW_SCALE_SHIFT := 4
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else ifeq ($(CONFIG_KASAN_GENERIC), y)
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KASAN_SHADOW_SCALE_SHIFT := 3
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endif
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KBUILD_CFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
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KBUILD_CPPFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
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KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
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core-y += arch/arm64/
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libs-y := arch/arm64/lib/ $(libs-y)
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libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
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# Default target when executing plain make
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boot := arch/arm64/boot
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KBUILD_IMAGE := $(boot)/Image.gz
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all: Image.gz
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Image: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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Image.%: Image
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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zinstall install:
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += vdso_install
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vdso_install:
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso $@
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$(if $(CONFIG_COMPAT_VDSO), \
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
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# We use MRPROPER_FILES and CLEAN_FILES now
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archclean:
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$(Q)$(MAKE) $(clean)=$(boot)
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ifeq ($(KBUILD_EXTMOD),)
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# We need to generate vdso-offsets.h before compiling certain files in kernel/.
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# In order to do that, we should use the archprepare target, but we can't since
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# asm-offsets.h is included in some files used to generate vdso-offsets.h, and
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# asm-offsets.h is built in prepare0, for which archprepare is a dependency.
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# Therefore we need to generate the header after prepare0 has been made, hence
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# this hack.
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prepare: vdso_prepare
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vdso_prepare: prepare0
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h
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$(if $(CONFIG_COMPAT_VDSO),$(Q)$(MAKE) \
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$(build)=arch/arm64/kernel/vdso32 \
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include/generated/vdso32-offsets.h)
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endif
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define archhelp
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echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
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echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
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echo ' install - Install uncompressed kernel'
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echo ' zinstall - Install compressed kernel'
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echo ' Install using (your) ~/bin/installkernel or'
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echo ' (distribution) /sbin/installkernel or'
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echo ' install to $$(INSTALL_PATH) and run lilo'
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endef
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