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![Sumanth Korikkar](/assets/img/avatar_default.png)
When the kernel is built with CONFIG_PIE_BUILD option enabled it uses dynamic symbols, for which the linker does not allow more than 64K number of entries. This can break features like kpatch. Hence, whenever possible the kernel is built with CONFIG_PIE_BUILD option disabled. For that support of unaligned symbols generated by linker scripts in the compiler is necessary. However, older compilers might lack such support. In that case the build process resorts to CONFIG_PIE_BUILD option-enabled build. Compile object files with -fPIC option and then link the kernel binary with -no-pie linker option. As result, the dynamic symbols are not generated and not only kpatch feature succeeds, but also the whole CONFIG_PIE_BUILD option-enabled code could be dropped. [ agordeev: Reworded the commit message ] Suggested-by: Ulrich Weigand <ulrich.weigand@de.ibm.com> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
174 lines
5.8 KiB
Makefile
174 lines
5.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# s390/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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# Copyright (C) 1994 by Linus Torvalds
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#
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LD_BFD := elf64-s390
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KBUILD_LDFLAGS := -m elf64_s390
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KBUILD_AFLAGS_MODULE += -fPIC
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KBUILD_CFLAGS_MODULE += -fPIC
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KBUILD_AFLAGS += -m64
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KBUILD_CFLAGS += -m64
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KBUILD_CFLAGS += -fPIC
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LDFLAGS_vmlinux := -no-pie --emit-relocs --discard-none
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extra_tools := relocs
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aflags_dwarf := -Wa,-gdwarf-2
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KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__
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ifndef CONFIG_AS_IS_LLVM
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KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))
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endif
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KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2 -mpacked-stack
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KBUILD_CFLAGS_DECOMPRESSOR += -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY
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KBUILD_CFLAGS_DECOMPRESSOR += -D__DECOMPRESSOR
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KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float -mbackchain
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KBUILD_CFLAGS_DECOMPRESSOR += -fno-asynchronous-unwind-tables
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KBUILD_CFLAGS_DECOMPRESSOR += -ffreestanding
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KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector
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KBUILD_CFLAGS_DECOMPRESSOR += -fPIE
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KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)
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KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
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KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
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KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)
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UTS_MACHINE := s390x
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STACK_SIZE := $(if $(CONFIG_KASAN),65536,16384)
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CHECKFLAGS += -D__s390__ -D__s390x__
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export LD_BFD
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mflags-$(CONFIG_MARCH_Z10) := -march=z10
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mflags-$(CONFIG_MARCH_Z196) := -march=z196
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mflags-$(CONFIG_MARCH_ZEC12) := -march=zEC12
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mflags-$(CONFIG_MARCH_Z13) := -march=z13
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mflags-$(CONFIG_MARCH_Z14) := -march=z14
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mflags-$(CONFIG_MARCH_Z15) := -march=z15
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mflags-$(CONFIG_MARCH_Z16) := -march=z16
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export CC_FLAGS_MARCH := $(mflags-y)
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aflags-y += $(mflags-y)
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cflags-y += $(mflags-y)
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cflags-$(CONFIG_MARCH_Z10_TUNE) += -mtune=z10
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cflags-$(CONFIG_MARCH_Z196_TUNE) += -mtune=z196
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cflags-$(CONFIG_MARCH_ZEC12_TUNE) += -mtune=zEC12
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cflags-$(CONFIG_MARCH_Z13_TUNE) += -mtune=z13
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cflags-$(CONFIG_MARCH_Z14_TUNE) += -mtune=z14
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cflags-$(CONFIG_MARCH_Z15_TUNE) += -mtune=z15
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cflags-$(CONFIG_MARCH_Z16_TUNE) += -mtune=z16
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cflags-y += -Wa,-I$(srctree)/arch/$(ARCH)/include
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#
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# Prevent tail-call optimizations, to get clearer backtraces:
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#
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cflags-$(CONFIG_FRAME_POINTER) += -fno-optimize-sibling-calls
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KBUILD_AFLAGS_DECOMPRESSOR += $(aflags-y)
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KBUILD_CFLAGS_DECOMPRESSOR += $(cflags-y)
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ifneq ($(call cc-option,-mstack-size=8192 -mstack-guard=128),)
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CC_FLAGS_CHECK_STACK := -mstack-size=$(STACK_SIZE)
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ifeq ($(call cc-option,-mstack-size=8192),)
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CC_FLAGS_CHECK_STACK += -mstack-guard=$(CONFIG_STACK_GUARD)
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endif
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export CC_FLAGS_CHECK_STACK
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cflags-$(CONFIG_CHECK_STACK) += $(CC_FLAGS_CHECK_STACK)
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endif
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ifdef CONFIG_EXPOLINE
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ifdef CONFIG_EXPOLINE_EXTERN
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CC_FLAGS_EXPOLINE := -mindirect-branch=thunk-extern
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CC_FLAGS_EXPOLINE += -mfunction-return=thunk-extern
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else
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CC_FLAGS_EXPOLINE := -mindirect-branch=thunk
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CC_FLAGS_EXPOLINE += -mfunction-return=thunk
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endif
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CC_FLAGS_EXPOLINE += -mindirect-branch-table
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export CC_FLAGS_EXPOLINE
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cflags-y += $(CC_FLAGS_EXPOLINE) -DCC_USING_EXPOLINE
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aflags-y += -DCC_USING_EXPOLINE
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endif
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ifdef CONFIG_FUNCTION_TRACER
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ifeq ($(call cc-option,-mfentry -mnop-mcount),)
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# make use of hotpatch feature if the compiler supports it
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cc_hotpatch := -mhotpatch=0,3
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ifneq ($(call cc-option,$(cc_hotpatch)),)
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CC_FLAGS_FTRACE := $(cc_hotpatch)
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KBUILD_AFLAGS += -DCC_USING_HOTPATCH
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KBUILD_CFLAGS += -DCC_USING_HOTPATCH
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endif
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endif
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endif
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# Test CFI features of binutils
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cfi := $(call as-instr,.cfi_startproc\n.cfi_val_offset 15$(comma)-160\n.cfi_endproc,-DCONFIG_AS_CFI_VAL_OFFSET=1)
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KBUILD_CFLAGS += -mpacked-stack -mbackchain -msoft-float $(cflags-y)
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KBUILD_CFLAGS += -pipe -Wno-sign-compare
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables $(cfi)
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KBUILD_AFLAGS += $(aflags-y) $(cfi)
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export KBUILD_AFLAGS_DECOMPRESSOR
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export KBUILD_CFLAGS_DECOMPRESSOR
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OBJCOPYFLAGS := -O binary
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libs-y += arch/s390/lib/
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boot := arch/s390/boot
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syscalls := arch/s390/kernel/syscalls
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tools := arch/s390/tools
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all: bzImage
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#KBUILD_IMAGE is necessary for packaging targets like rpm-pkg, deb-pkg...
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KBUILD_IMAGE := $(boot)/bzImage
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install:
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$(call cmd,install)
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bzImage: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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zfcpdump:
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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archheaders:
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$(Q)$(MAKE) $(build)=$(syscalls) uapi
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archprepare:
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$(Q)$(MAKE) $(build)=$(syscalls) kapi
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$(Q)$(MAKE) $(build)=$(tools) kapi $(extra_tools)
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ifeq ($(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) $(build)=arch/s390/kernel/vdso64 include/generated/vdso64-offsets.h
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$(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
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$(build)=arch/s390/kernel/vdso32 include/generated/vdso32-offsets.h)
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vdso-install-y += arch/s390/kernel/vdso64/vdso64.so.dbg
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vdso-install-$(CONFIG_COMPAT) += arch/s390/kernel/vdso32/vdso32.so.dbg
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endif
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# Don't use tabs in echo arguments
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define archhelp
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echo '* bzImage - Kernel image for IPL ($(boot)/bzImage)'
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echo ' install - Install kernel using'
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echo ' (your) ~/bin/$(INSTALLKERNEL) or'
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echo ' (distribution) /sbin/$(INSTALLKERNEL) or'
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echo ' install to $$(INSTALL_PATH)'
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endef
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