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The actual intention is that no dynamic relocation exists in the VDSO. For this the VDSO build validates that the resulting .so file does not have any relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture, which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative relocations too. However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If a port fails to determine the exact .rel[a].dyn size, the trailing zeros become R_*_NONE relocations. E.g. ld's powerpc port recently fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are generally a no-op in the dynamic loaders. So just ignore them. Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting .so file does not contain any R_* relocation entries except R_*_NONE. Signed-off-by: Fangrui Song <maskray@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for aarch64 Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for vDSO, aarch64 Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com
206 lines
5.9 KiB
Makefile
206 lines
5.9 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# Objects to go into the VDSO.
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# Sanitizer runtimes are unavailable and cannot be linked here.
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KCSAN_SANITIZE := n
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# Include the generic Makefile to check the built vdso.
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include $(srctree)/lib/vdso/Makefile
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obj-vdso-y := elf.o vgettimeofday.o sigreturn.o
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# Common compiler flags between ABIs.
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ccflags-vdso := \
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$(filter -I%,$(KBUILD_CFLAGS)) \
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$(filter -E%,$(KBUILD_CFLAGS)) \
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$(filter -mmicromips,$(KBUILD_CFLAGS)) \
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$(filter -march=%,$(KBUILD_CFLAGS)) \
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$(filter -m%-float,$(KBUILD_CFLAGS)) \
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$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
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$(CLANG_FLAGS) \
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-D__VDSO__
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ifndef CONFIG_64BIT
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ccflags-vdso += -DBUILD_VDSO32
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endif
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#
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# The -fno-jump-tables flag only prevents the compiler from generating
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# jump tables but does not prevent the compiler from emitting absolute
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# offsets.
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cflags-vdso := $(ccflags-vdso) \
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$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
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-O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
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-mrelax-pic-calls $(call cc-option, -mexplicit-relocs) \
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-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
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$(call cc-option, -fno-asynchronous-unwind-tables)
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aflags-vdso := $(ccflags-vdso) \
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-D__ASSEMBLY__ -Wa,-gdwarf-2
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o = -include $(c-gettimeofday-y)
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# config-n32-o32-env.c prepares the environment to build a 32bit vDSO
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# library on a 64bit kernel.
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# Note: Needs to be included before than the generic library.
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CFLAGS_vgettimeofday-o32.o = -include $(srctree)/$(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
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CFLAGS_vgettimeofday-n32.o = -include $(srctree)/$(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
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endif
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
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ifdef CONFIG_MIPS_DISABLE_VDSO
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obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))
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endif
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# VDSO linker flags.
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ldflags-y := -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \
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$(filter -E%,$(KBUILD_CFLAGS)) -shared \
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-G 0 --eh-frame-hdr --hash-style=sysv --build-id=sha1 -T
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CFLAGS_REMOVE_vdso.o = $(CC_FLAGS_FTRACE)
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GCOV_PROFILE := n
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UBSAN_SANITIZE := n
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KCOV_INSTRUMENT := n
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# Check that we don't have PIC 'jalr t9' calls left
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quiet_cmd_vdso_mips_check = VDSOCHK $@
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cmd_vdso_mips_check = if $(OBJDUMP) --disassemble $@ | grep -E -h "jalr.*t9" > /dev/null; \
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then (echo >&2 "$@: PIC 'jalr t9' calls are not supported"; \
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rm -f $@; /bin/false); fi
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#
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# Shared build commands.
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#
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quiet_cmd_vdsold_and_vdso_check = LD $@
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cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check); $(cmd_vdso_mips_check)
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quiet_cmd_vdsoas_o_S = AS $@
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cmd_vdsoas_o_S = $(CC) $(a_flags) -c -o $@ $<
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# Strip rule for the raw .so files
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$(obj)/%.so.raw: OBJCOPYFLAGS := -S
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$(obj)/%.so.raw: $(obj)/%.so.dbg.raw FORCE
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$(call if_changed,objcopy)
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hostprogs := genvdso
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quiet_cmd_genvdso = GENVDSO $@
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define cmd_genvdso
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$(foreach file,$(filter %.raw,$^),cp $(file) $(file:%.raw=%) &&) \
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$(obj)/genvdso $(<:%.raw=%) $(<:%.dbg.raw=%) $@ $(VDSO_NAME)
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endef
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#
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# Build native VDSO.
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#
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native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS))
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targets += $(obj-vdso-y)
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targets += vdso.lds
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targets += vdso.so.dbg.raw vdso.so.raw
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targets += vdso.so.dbg vdso.so
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targets += vdso-image.c
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obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o)
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$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi)
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$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
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$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) $(native-abi)
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$(obj)/vdso.so.dbg.raw: $(obj)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold_and_vdso_check)
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$(obj)/vdso-image.c: $(obj)/vdso.so.dbg.raw $(obj)/vdso.so.raw \
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$(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-image.o
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#
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# Build O32 VDSO.
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#
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# Define these outside the ifdef to ensure they are picked up by clean.
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targets += $(obj-vdso-y:%.o=%-o32.o)
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targets += vdso-o32.lds
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targets += vdso-o32.so.dbg.raw vdso-o32.so.raw
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targets += vdso-o32.so.dbg vdso-o32.so
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targets += vdso-o32-image.c
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ifdef CONFIG_MIPS32_O32
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obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o)
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$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32
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$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32
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$(obj)/%-o32.o: $(src)/%.S FORCE
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$(call if_changed_dep,vdsoas_o_S)
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$(obj)/%-o32.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=32
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$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
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$(call if_changed_dep,cpp_lds_S)
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$(obj)/vdso-o32.so.dbg.raw: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
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$(call if_changed,vdsold_and_vdso_check)
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$(obj)/vdso-o32-image.c: VDSO_NAME := o32
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$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg.raw $(obj)/vdso-o32.so.raw \
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$(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-o32-image.o
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endif
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#
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# Build N32 VDSO.
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#
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targets += $(obj-vdso-y:%.o=%-n32.o)
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targets += vdso-n32.lds
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targets += vdso-n32.so.dbg.raw vdso-n32.so.raw
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targets += vdso-n32.so.dbg vdso-n32.so
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targets += vdso-n32-image.c
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ifdef CONFIG_MIPS32_N32
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obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o)
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$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32
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$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32
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$(obj)/%-n32.o: $(src)/%.S FORCE
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$(call if_changed_dep,vdsoas_o_S)
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$(obj)/%-n32.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=n32
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$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
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$(call if_changed_dep,cpp_lds_S)
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$(obj)/vdso-n32.so.dbg.raw: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
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$(call if_changed,vdsold_and_vdso_check)
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$(obj)/vdso-n32-image.c: VDSO_NAME := n32
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$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg.raw $(obj)/vdso-n32.so.raw \
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$(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-n32-image.o
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endif
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# FIXME: Need install rule for debug.
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# Needs to deal with dependency for generation of dbg by cmd_genvdso...
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