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>
219 lines
7.8 KiB
Makefile
219 lines
7.8 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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COMPAT_GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE_COMPAT)elfedit))
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COMPAT_GCC_TOOLCHAIN := $(realpath $(COMPAT_GCC_TOOLCHAIN_DIR)/..)
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CC_COMPAT_CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE_COMPAT:%-=%))
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CC_COMPAT_CLANG_FLAGS += --prefix=$(COMPAT_GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE_COMPAT))
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CC_COMPAT_CLANG_FLAGS += -no-integrated-as -Qunused-arguments
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ifneq ($(COMPAT_GCC_TOOLCHAIN),)
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CC_COMPAT_CLANG_FLAGS += --gcc-toolchain=$(COMPAT_GCC_TOOLCHAIN)
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endif
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CC_COMPAT ?= $(CC)
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CC_COMPAT += $(CC_COMPAT_CLANG_FLAGS)
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ifneq ($(LLVM),)
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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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else
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CC_COMPAT ?= $(CROSS_COMPILE_COMPAT)gcc
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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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cc32-as-instr = $(call try-run,\
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printf "%b\n" "$(1)" | $(CC_COMPAT) $(VDSO_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
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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 -isystem $(shell $(CC_COMPAT) -print-file-name=include)
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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 := $(VDSO_CPPFLAGS)
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ifneq ($(shell $(CC_COMPAT) --version 2>&1 | head -n 1 | grep clang),)
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VDSO_CAFLAGS += --target=$(notdir $(CROSS_COMPILE_COMPAT:%-=%))
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endif
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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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# Try to compile for ARMv8. If the compiler is too old and doesn't support it,
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# fall back to v7. There is no easy way to check for what architecture the code
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# is being compiled, so define a macro specifying that (see arch/arm/Makefile).
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VDSO_CAFLAGS += $(call cc32-option,-march=armv8-a -D__LINUX_ARM_ARCH__=8,\
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-march=armv7-a -D__LINUX_ARM_ARCH__=7)
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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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-std=gnu89
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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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# Check for binutils support for dmb ishld
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dmbinstr := $(call cc32-as-instr,dmb ishld,-DCONFIG_AS_DMB_ISHLD=1)
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VDSO_CFLAGS += $(dmbinstr)
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VDSO_AFLAGS += $(dmbinstr)
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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 += -nostdlib -shared --hash-style=sysv --build-id=sha1
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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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# Force dependency (vdso.s includes vdso.so through incbin)
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$(obj)/vdso.o: $(obj)/vdso.so
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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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