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e1789d7c75
Andrew Cooper suggested upgrading the orphan section warning to a hard link error. However Nathan Chancellor said outright turning the warning into an error with no escape hatch might be too aggressive, as we have had these warnings triggered by new compiler generated sections, and suggested turning orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed and emphasized that the mandate from Linus is that we should avoid breaking builds. It wrecks bisection, it causes problems across compiler versions, etc. Thus upgrade the orphan section warning to a hard link error only if CONFIG_WERROR is set. Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com> Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Xin Li <xin3.li@intel.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20221025073023.16137-2-xin3.li@intel.com
190 lines
6.5 KiB
Makefile
190 lines
6.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for vdso32
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#
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# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
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# the inclusion of generic Makefile.
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ARCH_REL_TYPE_ABS := R_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32
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include $(srctree)/lib/vdso/Makefile
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# Same as cc-*option, but using CC_COMPAT instead of CC
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ifeq ($(CONFIG_CC_IS_CLANG), y)
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CC_COMPAT ?= $(CC)
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CC_COMPAT += --target=arm-linux-gnueabi
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else
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CC_COMPAT ?= $(CROSS_COMPILE_COMPAT)gcc
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endif
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ifeq ($(CONFIG_LD_IS_LLD), y)
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LD_COMPAT ?= $(LD)
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else
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LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)ld
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endif
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cc32-option = $(call try-run,\
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$(CC_COMPAT) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
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cc32-disable-warning = $(call try-run,\
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$(CC_COMPAT) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
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# We cannot use the global flags to compile the vDSO files, the main reason
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# being that the 32-bit compiler may be older than the main (64-bit) compiler
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# and therefore may not understand flags set using $(cc-option ...). Besides,
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# arch-specific options should be taken from the arm Makefile instead of the
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# arm64 one.
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# As a result we set our own flags here.
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# KBUILD_CPPFLAGS and NOSTDINC_FLAGS from top-level Makefile
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VDSO_CPPFLAGS := -DBUILD_VDSO -D__KERNEL__ -nostdinc
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VDSO_CPPFLAGS += -isystem $(shell $(CC_COMPAT) -print-file-name=include 2>/dev/null)
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VDSO_CPPFLAGS += $(LINUXINCLUDE)
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# Common C and assembly flags
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# From top-level Makefile
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VDSO_CAFLAGS := $(VDSO_CPPFLAGS)
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VDSO_CAFLAGS += $(call cc32-option,-fno-PIE)
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ifdef CONFIG_DEBUG_INFO
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VDSO_CAFLAGS += -g
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endif
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# From arm Makefile
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VDSO_CAFLAGS += $(call cc32-option,-fno-dwarf2-cfi-asm)
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VDSO_CAFLAGS += -mabi=aapcs-linux -mfloat-abi=soft
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ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
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VDSO_CAFLAGS += -mbig-endian
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else
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VDSO_CAFLAGS += -mlittle-endian
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endif
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# From arm vDSO Makefile
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VDSO_CAFLAGS += -fPIC -fno-builtin -fno-stack-protector
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VDSO_CAFLAGS += -DDISABLE_BRANCH_PROFILING
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VDSO_CAFLAGS += -march=armv8-a
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VDSO_CFLAGS := $(VDSO_CAFLAGS)
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VDSO_CFLAGS += -DENABLE_COMPAT_VDSO=1
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# KBUILD_CFLAGS from top-level Makefile
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VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
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-fno-strict-aliasing -fno-common \
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-Werror-implicit-function-declaration \
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-Wno-format-security \
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-Wdeclaration-after-statement \
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-std=gnu11
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VDSO_CFLAGS += -O2
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# Some useful compiler-dependent flags from top-level Makefile
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VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,)
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VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign)
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VDSO_CFLAGS += -fno-strict-overflow
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VDSO_CFLAGS += $(call cc32-option,-Werror=strict-prototypes)
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VDSO_CFLAGS += -Werror=date-time
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VDSO_CFLAGS += $(call cc32-option,-Werror=incompatible-pointer-types)
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# The 32-bit compiler does not provide 128-bit integers, which are used in
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# some headers that are indirectly included from the vDSO code.
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# This hack makes the compiler happy and should trigger a warning/error if
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# variables of such type are referenced.
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VDSO_CFLAGS += -D__uint128_t='void*'
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# Silence some warnings coming from headers that operate on long's
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# (on GCC 4.8 or older, there is unfortunately no way to silence this warning)
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VDSO_CFLAGS += $(call cc32-disable-warning,shift-count-overflow)
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VDSO_CFLAGS += -Wno-int-to-pointer-cast
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# Compile as THUMB2 or ARM. Unwinding via frame-pointers in THUMB2 is
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# unreliable.
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ifeq ($(CONFIG_THUMB2_COMPAT_VDSO), y)
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VDSO_CFLAGS += -mthumb -fomit-frame-pointer
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else
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VDSO_CFLAGS += -marm
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endif
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VDSO_AFLAGS := $(VDSO_CAFLAGS)
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VDSO_AFLAGS += -D__ASSEMBLY__
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# From arm vDSO Makefile
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VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1
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VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096
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VDSO_LDFLAGS += -shared --hash-style=sysv --build-id=sha1
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VDSO_LDFLAGS += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
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# Borrow vdsomunge.c from the arm vDSO
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# We have to use a relative path because scripts/Makefile.host prefixes
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# $(hostprogs) with $(obj)
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munge := ../../../arm/vdso/vdsomunge
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hostprogs := $(munge)
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c-obj-vdso := note.o
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c-obj-vdso-gettimeofday := vgettimeofday.o
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ifneq ($(c-gettimeofday-y),)
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VDSO_CFLAGS_gettimeofday_o += -include $(c-gettimeofday-y)
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endif
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VDSO_CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
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# Build rules
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targets := $(c-obj-vdso) $(c-obj-vdso-gettimeofday) $(asm-obj-vdso) vdso.so vdso.so.dbg vdso.so.raw
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c-obj-vdso := $(addprefix $(obj)/, $(c-obj-vdso))
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c-obj-vdso-gettimeofday := $(addprefix $(obj)/, $(c-obj-vdso-gettimeofday))
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asm-obj-vdso := $(addprefix $(obj)/, $(asm-obj-vdso))
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obj-vdso := $(c-obj-vdso) $(c-obj-vdso-gettimeofday) $(asm-obj-vdso)
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targets += vdso.lds
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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include/generated/vdso32-offsets.h: $(obj)/vdso.so.dbg FORCE
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$(call if_changed,vdsosym)
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# Strip rule for vdso.so
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$(obj)/vdso.so: OBJCOPYFLAGS := -S
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$(obj)/vdso.so: $(obj)/vdso.so.dbg FORCE
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$(call if_changed,objcopy)
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$(obj)/vdso.so.dbg: $(obj)/vdso.so.raw $(obj)/$(munge) FORCE
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$(call if_changed,vdsomunge)
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# Link rule for the .so file, .lds has to be first
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$(obj)/vdso.so.raw: $(src)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold_and_vdso_check)
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# Compilation rules for the vDSO sources
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$(c-obj-vdso): %.o: %.c FORCE
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$(call if_changed_dep,vdsocc)
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$(c-obj-vdso-gettimeofday): %.o: %.c FORCE
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$(call if_changed_dep,vdsocc_gettimeofday)
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$(asm-obj-vdso): %.o: %.S FORCE
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$(call if_changed_dep,vdsoas)
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# Actual build commands
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quiet_cmd_vdsold_and_vdso_check = LD32 $@
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cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check)
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quiet_cmd_vdsold = LD32 $@
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cmd_vdsold = $(LD_COMPAT) $(VDSO_LDFLAGS) \
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-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
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quiet_cmd_vdsocc = CC32 $@
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cmd_vdsocc = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) -c -o $@ $<
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quiet_cmd_vdsocc_gettimeofday = CC32 $@
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cmd_vdsocc_gettimeofday = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) $(VDSO_CFLAGS_gettimeofday_o) -c -o $@ $<
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quiet_cmd_vdsoas = AS32 $@
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cmd_vdsoas = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_AFLAGS) -c -o $@ $<
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quiet_cmd_vdsomunge = MUNGE $@
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cmd_vdsomunge = $(obj)/$(munge) $< $@
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# Generate vDSO offsets using helper script (borrowed from the 64-bit vDSO)
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gen-vdsosym := $(srctree)/$(src)/../vdso/gen_vdso_offsets.sh
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quiet_cmd_vdsosym = VDSOSYM $@
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# The AArch64 nm should be able to read an AArch32 binary
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cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
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# Install commands for the unstripped file
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quiet_cmd_vdso_install = INSTALL32 $@
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cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/vdso32.so
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vdso.so: $(obj)/vdso.so.dbg
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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vdso_install: vdso.so
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