linux/arch/mips/vdso/Makefile
Paul Burton 07015d7a10
MIPS: Disable VDSO time functionality on microMIPS
A check we're about to add to pick up on function calls that depend on
bogus use of the GOT in the VDSO picked up on instances of such function
calls in microMIPS builds. Since the code appears genuinely problematic,
and given the relatively small amount of use & testing that microMIPS
sees, go ahead & disable the VDSO for microMIPS builds.

Signed-off-by: Paul Burton <paulburton@kernel.org>
2020-02-15 12:44:03 -08:00

238 lines
6.8 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
# Objects to go into the VDSO.
# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
# the inclusion of generic Makefile.
ARCH_REL_TYPE_ABS := R_MIPS_JUMP_SLOT|R_MIPS_GLOB_DAT
include $(srctree)/lib/vdso/Makefile
obj-vdso-y := elf.o vgettimeofday.o sigreturn.o
# Common compiler flags between ABIs.
ccflags-vdso := \
$(filter -I%,$(KBUILD_CFLAGS)) \
$(filter -E%,$(KBUILD_CFLAGS)) \
$(filter -mmicromips,$(KBUILD_CFLAGS)) \
$(filter -march=%,$(KBUILD_CFLAGS)) \
$(filter -m%-float,$(KBUILD_CFLAGS)) \
$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
-D__VDSO__
ifndef CONFIG_64BIT
ccflags-vdso += -DBUILD_VDSO32
endif
ifdef CONFIG_CC_IS_CLANG
ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
endif
#
# The -fno-jump-tables flag only prevents the compiler from generating
# jump tables but does not prevent the compiler from emitting absolute
# offsets.
cflags-vdso := $(ccflags-vdso) \
$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
-O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
-mrelax-pic-calls -mexplicit-relocs \
-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
$(call cc-option, -fno-asynchronous-unwind-tables) \
$(call cc-option, -fno-stack-protector)
aflags-vdso := $(ccflags-vdso) \
-D__ASSEMBLY__ -Wa,-gdwarf-2
ifneq ($(c-gettimeofday-y),)
CFLAGS_vgettimeofday.o = -include $(c-gettimeofday-y)
# config-n32-o32-env.c prepares the environment to build a 32bit vDSO
# library on a 64bit kernel.
# Note: Needs to be included before than the generic library.
CFLAGS_vgettimeofday-o32.o = -include $(srctree)/$(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
CFLAGS_vgettimeofday-n32.o = -include $(srctree)/$(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
endif
CFLAGS_REMOVE_vgettimeofday.o = -pg
DISABLE_VDSO := n
#
# For the pre-R6 code in arch/mips/vdso/vdso.h for locating
# the base address of VDSO, the linker will emit a R_MIPS_PC32
# relocation in binutils > 2.25 but it will fail with older versions
# because that relocation is not supported for that symbol. As a result
# of which we are forced to disable the VDSO symbols when building
# with < 2.25 binutils on pre-R6 kernels. For more references on why we
# can't use other methods to get the base address of VDSO please refer to
# the comments on that file.
#
ifndef CONFIG_CPU_MIPSR6
ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
$(warning MIPS VDSO requires binutils >= 2.25)
DISABLE_VDSO := y
endif
endif
#
# GCC (at least up to version 9.2) appears to emit function calls that make use
# of the GOT when targeting microMIPS, which we can't use in the VDSO due to
# the lack of relocations. As such, we disable the VDSO for microMIPS builds.
#
ifdef CONFIG_CPU_MICROMIPS
DISABLE_VDSO := y
endif
ifeq ($(DISABLE_VDSO),y)
obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))
ccflags-vdso += -DDISABLE_MIPS_VDSO
endif
# VDSO linker flags.
VDSO_LDFLAGS := \
-Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \
$(addprefix -Wl$(comma),$(filter -E%,$(KBUILD_CFLAGS))) \
-nostdlib -shared -Wl,--hash-style=sysv -Wl,--build-id
CFLAGS_REMOVE_vdso.o = -pg
GCOV_PROFILE := n
UBSAN_SANITIZE := n
KCOV_INSTRUMENT := n
#
# Shared build commands.
#
quiet_cmd_vdsold_and_vdso_check = LD $@
cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check)
quiet_cmd_vdsold = VDSO $@
cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \
-Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
quiet_cmd_vdsoas_o_S = AS $@
cmd_vdsoas_o_S = $(CC) $(a_flags) -c -o $@ $<
# Strip rule for the raw .so files
$(obj)/%.so.raw: OBJCOPYFLAGS := -S
$(obj)/%.so.raw: $(obj)/%.so.dbg.raw FORCE
$(call if_changed,objcopy)
hostprogs := genvdso
quiet_cmd_genvdso = GENVDSO $@
define cmd_genvdso
$(foreach file,$(filter %.raw,$^),cp $(file) $(file:%.raw=%) &&) \
$(obj)/genvdso $(<:%.raw=%) $(<:%.dbg.raw=%) $@ $(VDSO_NAME)
endef
#
# Build native VDSO.
#
native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS))
targets += $(obj-vdso-y)
targets += vdso.lds
targets += vdso.so.dbg.raw vdso.so.raw
targets += vdso.so.dbg vdso.so
targets += vdso-image.c
obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o)
$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi)
$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) $(native-abi)
$(obj)/vdso.so.dbg.raw: $(obj)/vdso.lds $(obj-vdso) FORCE
$(call if_changed,vdsold_and_vdso_check)
$(obj)/vdso-image.c: $(obj)/vdso.so.dbg.raw $(obj)/vdso.so.raw \
$(obj)/genvdso FORCE
$(call if_changed,genvdso)
obj-y += vdso-image.o
#
# Build O32 VDSO.
#
# Define these outside the ifdef to ensure they are picked up by clean.
targets += $(obj-vdso-y:%.o=%-o32.o)
targets += vdso-o32.lds
targets += vdso-o32.so.dbg.raw vdso-o32.so.raw
targets += vdso-o32.so.dbg vdso-o32.so
targets += vdso-o32-image.c
ifdef CONFIG_MIPS32_O32
obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o)
$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32
$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32
$(obj)/%-o32.o: $(src)/%.S FORCE
$(call if_changed_dep,vdsoas_o_S)
$(obj)/%-o32.o: $(src)/%.c FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=32
$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
$(call if_changed_dep,cpp_lds_S)
$(obj)/vdso-o32.so.dbg.raw: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
$(call if_changed,vdsold_and_vdso_check)
$(obj)/vdso-o32-image.c: VDSO_NAME := o32
$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg.raw $(obj)/vdso-o32.so.raw \
$(obj)/genvdso FORCE
$(call if_changed,genvdso)
obj-y += vdso-o32-image.o
endif
#
# Build N32 VDSO.
#
targets += $(obj-vdso-y:%.o=%-n32.o)
targets += vdso-n32.lds
targets += vdso-n32.so.dbg.raw vdso-n32.so.raw
targets += vdso-n32.so.dbg vdso-n32.so
targets += vdso-n32-image.c
ifdef CONFIG_MIPS32_N32
obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o)
$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32
$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32
$(obj)/%-n32.o: $(src)/%.S FORCE
$(call if_changed_dep,vdsoas_o_S)
$(obj)/%-n32.o: $(src)/%.c FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=n32
$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
$(call if_changed_dep,cpp_lds_S)
$(obj)/vdso-n32.so.dbg.raw: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
$(call if_changed,vdsold_and_vdso_check)
$(obj)/vdso-n32-image.c: VDSO_NAME := n32
$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg.raw $(obj)/vdso-n32.so.raw \
$(obj)/genvdso FORCE
$(call if_changed,genvdso)
obj-y += vdso-n32-image.o
endif
# FIXME: Need install rule for debug.
# Needs to deal with dependency for generation of dbg by cmd_genvdso...