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a5b8ca97fb
arm64 descends into each vdso directory twice; first in vdso_prepare, second during the ordinary build process. PPC mimicked it and uncovered a problem [1]. In the first descend, Kbuild directly visits the vdso directories, therefore it does not inherit subdir-ccflags-y from upper directories. This means the command line parameters may differ between the two. If it happens, the offset values in the generated headers might be different from real offsets of vdso.so in the kernel. This potential danger should be avoided. The vdso directories are built in the vdso_prepare stage, so the second descend is unneeded. [1]: https://lore.kernel.org/linux-kbuild/CAK7LNARAkJ3_-4gX0VA2UkapbOftuzfSTVMBbgbw=HD8n7N+7w@mail.gmail.com/T/#ma10dcb961fda13f36d42d58fa6cb2da988b7e73a Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Link: https://lore.kernel.org/r/20201218024540.1102650-1-masahiroy@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
207 lines
6.8 KiB
Makefile
207 lines
6.8 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 \
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include/generated/vdso-offsets.h arch/arm64/kernel/vdso/vdso.so
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ifdef CONFIG_COMPAT_VDSO
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \
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include/generated/vdso32-offsets.h arch/arm64/kernel/vdso32/vdso.so
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endif
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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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