arch/arm64/kernel/vdso/Makefile

# SPDX-License-Identifier: GPL-2.0
#
# Building a vDSO image for AArch64.
#
# Author: Will Deacon <will.deacon@arm.com>
# Heavily based on the vDSO Makefiles for other archs.
#

# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
# the inclusion of generic Makefile.
ARCH_REL_TYPE_ABS := R_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
include $(srctree)/lib/vdso/Makefile

obj-vdso := vgettimeofday.o note.o sigreturn.o

# Build rules
targets := $(obj-vdso) vdso.so vdso.so.dbg
obj-vdso := $(addprefix $(obj)/, $(obj-vdso))

btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti

# -Bsymbolic has been added for consistency with arm, the compat vDSO and
# potential future proofing if we end up with internal calls to the exported
# routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
# preparation in build-time C")).
ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv	\
	     -Bsymbolic $(call ld-option, --no-eh-frame-hdr) --build-id -n	\
	     $(btildflags-y) -T

ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
ccflags-y += -DDISABLE_BRANCH_PROFILING

CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS)
KBUILD_CFLAGS			+= $(DISABLE_LTO)
KASAN_SANITIZE			:= n
UBSAN_SANITIZE			:= n
OBJECT_FILES_NON_STANDARD	:= y
KCOV_INSTRUMENT			:= n

CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables

ifneq ($(c-gettimeofday-y),)
  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
endif

# Clang versions less than 8 do not support -mcmodel=tiny
ifeq ($(CONFIG_CC_IS_CLANG), y)
  ifeq ($(shell test $(CONFIG_CLANG_VERSION) -lt 80000; echo $$?),0)
    CFLAGS_REMOVE_vgettimeofday.o += -mcmodel=tiny
  endif
endif

# Disable gcov profiling for VDSO code
GCOV_PROFILE := n

obj-y += vdso.o
targets += vdso.lds
CPPFLAGS_vdso.lds += -P -C -U$(ARCH)

# Force dependency (incbin is bad)
$(obj)/vdso.o : $(obj)/vdso.so

# Link rule for the .so file, .lds has to be first
$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
	$(call if_changed,vdsold_and_vdso_check)

# Strip rule for the .so file
$(obj)/%.so: OBJCOPYFLAGS := -S
$(obj)/%.so: $(obj)/%.so.dbg FORCE
	$(call if_changed,objcopy)

# Generate VDSO offsets using helper script
gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
quiet_cmd_vdsosym = VDSOSYM $@
      cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@

include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
	$(call if_changed,vdsosym)

# Actual build commands
quiet_cmd_vdsold_and_vdso_check = LD      $@
      cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check)

# Install commands for the unstripped file
quiet_cmd_vdso_install = INSTALL $@
      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@

vdso.so: $(obj)/vdso.so.dbg
	@mkdir -p $(MODLIB)/vdso
	$(call cmd,vdso_install)

vdso_install: vdso.so