drivers/firmware/efi/libstub/Makefile - linux - Git at Google

 # SPDX-License-Identifier: GPL-2.0
 #
 # The stub may be linked into the kernel proper or into a separate boot binary,
 # but in either case, it executes before the kernel does (with MMU disabled) so
 # things like ftrace and stack-protector are likely to cause trouble if left
 # enabled, even if doing so doesn't break the build.
 #

 # non-x86 reuses KBUILD_CFLAGS, x86 does not
 cflags-y			:= $(KBUILD_CFLAGS)

 cflags-$(CONFIG_X86_32)		:= -march=i386
 cflags-$(CONFIG_X86_64)		:= -mcmodel=small
 cflags-$(CONFIG_X86)		+= -m$(BITS) -D__KERNEL__ \
 				   -fPIC -fno-strict-aliasing -mno-red-zone \
 				   -mno-mmx -mno-sse -fshort-wchar \
 				   -Wno-pointer-sign \
 				   $(call cc-disable-warning, address-of-packed-member) \
 				   $(call cc-disable-warning, gnu) \
 				   -fno-asynchronous-unwind-tables \
 				   $(CLANG_FLAGS)

 # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
 # disable the stackleak plugin
 cflags-$(CONFIG_ARM64)		+= -fpie $(DISABLE_STACKLEAK_PLUGIN) \
 				   -fno-unwind-tables -fno-asynchronous-unwind-tables
 cflags-$(CONFIG_ARM)		+= -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
 				   -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
 				   -DEFI_HAVE_STRCMP -fno-builtin -fpic \
 				   $(call cc-option,-mno-single-pic-base)
 cflags-$(CONFIG_RISCV)		+= -fpic -DNO_ALTERNATIVE -mno-relax
 cflags-$(CONFIG_LOONGARCH)	+= -fpie

 cflags-$(CONFIG_EFI_PARAMS_FROM_FDT)	+= -I$(srctree)/scripts/dtc/libfdt

 KBUILD_CFLAGS			:= $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
 				   -Os -DDISABLE_BRANCH_PROFILING \
 				   -include $(srctree)/include/linux/hidden.h \
 				   -D__NO_FORTIFY \
 				   -ffreestanding \
 				   -fno-stack-protector \
 				   $(call cc-option,-fno-addrsig) \
 				   -D__DISABLE_EXPORTS

 #
 # struct randomization only makes sense for Linux internal types, which the EFI
 # stub code never touches, so let's turn off struct randomization for the stub
 # altogether
 #
 KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))

 # remove SCS flags from all objects in this directory
 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
 # disable CFI
 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
 # disable LTO
 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))

 lib-y				:= efi-stub-helper.o gop.o secureboot.o tpm.o \
 				   file.o mem.o random.o randomalloc.o pci.o \
 				   skip_spaces.o lib-cmdline.o lib-ctype.o \
 				   alignedmem.o relocate.o printk.o vsprintf.o

 # include the stub's libfdt dependencies from lib/ when needed
 libfdt-deps			:= fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
 				   fdt_empty_tree.c fdt_sw.c

 lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
 				     $(patsubst %.c,lib-%.o,$(libfdt-deps))

 $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
 	$(call if_changed_rule,cc_o_c)

 lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o string.o intrinsics.o systable.o \
 				   screen_info.o efi-stub-entry.o

 lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= kaslr.o arm64.o arm64-stub.o smbios.o
 lib-$(CONFIG_X86)		+= x86-stub.o
 lib-$(CONFIG_X86_64)		+= x86-5lvl.o
 lib-$(CONFIG_RISCV)		+= kaslr.o riscv.o riscv-stub.o
 lib-$(CONFIG_LOONGARCH)		+= loongarch.o loongarch-stub.o

 CFLAGS_arm32-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)

 zboot-obj-$(CONFIG_RISCV)	:= lib-clz_ctz.o lib-ashldi3.o
 lib-$(CONFIG_EFI_ZBOOT)		+= zboot.o $(zboot-obj-y)

 lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o

 extra-y				:= $(lib-y)
 lib-y				:= $(patsubst %.o,%.stub.o,$(lib-y))

 # Even when -mbranch-protection=none is set, Clang will generate a
 # .note.gnu.property for code-less object files (like lib/ctype.c),
 # so work around this by explicitly removing the unwanted section.
 # https://llvm.org/pr46480
 STUBCOPY_FLAGS-y		+= --remove-section=.note.gnu.property

 STUBCOPY_RELOC-$(CONFIG_X86_32)	:= R_386_32
 STUBCOPY_RELOC-$(CONFIG_X86_64)	:= R_X86_64_64

 #
 # ARM discards the .data section because it disallows r/w data in the
 # decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
 # which are preserved explicitly by the decompressor linker script.
 #
 STUBCOPY_FLAGS-$(CONFIG_ARM)	+= --rename-section .data=.data.efistub	\
 				   --rename-section .bss=.bss.efistub,load,alloc
 STUBCOPY_RELOC-$(CONFIG_ARM)	:= R_ARM_ABS

 #
 # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
 # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
 # So let's apply the __init annotations at the section level, by prefixing
 # the section names directly. This will ensure that even all the inline string
 # literals are covered.
 # The fact that the stub and the kernel proper are essentially the same binary
 # also means that we need to be extra careful to make sure that the stub does
 # not rely on any absolute symbol references, considering that the virtual
 # kernel mapping that the linker uses is not active yet when the stub is
 # executing. So build all C dependencies of the EFI stub into libstub, and do
 # a verification pass to see if any absolute relocations exist in any of the
 # object files.
 #
 STUBCOPY_FLAGS-$(CONFIG_ARM64)	+= --prefix-alloc-sections=.init \
 				   --prefix-symbols=__efistub_
 STUBCOPY_RELOC-$(CONFIG_ARM64)	:= R_AARCH64_ABS

 # For RISC-V, we don't need anything special other than arm64. Keep all the
 # symbols in .init section and make sure that no absolute symbols references
 # exist.
 STUBCOPY_FLAGS-$(CONFIG_RISCV)	+= --prefix-alloc-sections=.init \
 				   --prefix-symbols=__efistub_
 STUBCOPY_RELOC-$(CONFIG_RISCV)	:= -E R_RISCV_HI20\|R_RISCV_$(BITS)\|R_RISCV_RELAX

 # For LoongArch, keep all the symbols in .init section and make sure that no
 # absolute symbols references exist.
 STUBCOPY_FLAGS-$(CONFIG_LOONGARCH)	+= --prefix-alloc-sections=.init \
 					   --prefix-symbols=__efistub_
 STUBCOPY_RELOC-$(CONFIG_LOONGARCH)	:= R_LARCH_MARK_LA

 $(obj)/%.stub.o: $(obj)/%.o FORCE
 	$(call if_changed,stubcopy)

 #
 # Strip debug sections and some other sections that may legally contain
 # absolute relocations, so that we can inspect the remaining sections for
 # such relocations. If none are found, regenerate the output object, but
 # this time, use objcopy and leave all sections in place.
 #
 quiet_cmd_stubcopy = STUBCPY $@
       cmd_stubcopy =							\
 	$(STRIP) --strip-debug -o $@ $<;				\
 	if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then		\
 		echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
 		/bin/false;						\
 	fi;								\
 	$(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@
	# SPDX-License-Identifier: GPL-2.0
	#
	# The stub may be linked into the kernel proper or into a separate boot binary,
	# but in either case, it executes before the kernel does (with MMU disabled) so
	# things like ftrace and stack-protector are likely to cause trouble if left
	# enabled, even if doing so doesn't break the build.
	#

	# non-x86 reuses KBUILD_CFLAGS, x86 does not
	cflags-y := $(KBUILD_CFLAGS)

	cflags-$(CONFIG_X86_32) := -march=i386
	cflags-$(CONFIG_X86_64) := -mcmodel=small
	cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \
	-fPIC -fno-strict-aliasing -mno-red-zone \
	-mno-mmx -mno-sse -fshort-wchar \
	-Wno-pointer-sign \
	$(call cc-disable-warning, address-of-packed-member) \
	$(call cc-disable-warning, gnu) \
	-fno-asynchronous-unwind-tables \
	$(CLANG_FLAGS)

	# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
	# disable the stackleak plugin
	cflags-$(CONFIG_ARM64) += -fpie $(DISABLE_STACKLEAK_PLUGIN) \
	-fno-unwind-tables -fno-asynchronous-unwind-tables
	cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
	-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
	-DEFI_HAVE_STRCMP -fno-builtin -fpic \
	$(call cc-option,-mno-single-pic-base)
	cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
	cflags-$(CONFIG_LOONGARCH) += -fpie

	cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt

	KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
	-Os -DDISABLE_BRANCH_PROFILING \
	-include $(srctree)/include/linux/hidden.h \
	-D__NO_FORTIFY \
	-ffreestanding \
	-fno-stack-protector \
	$(call cc-option,-fno-addrsig) \
	-D__DISABLE_EXPORTS

	#
	# struct randomization only makes sense for Linux internal types, which the EFI
	# stub code never touches, so let's turn off struct randomization for the stub
	# altogether
	#
	KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))

	# remove SCS flags from all objects in this directory
	KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
	# disable CFI
	KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
	# disable LTO
	KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))

	lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
	file.o mem.o random.o randomalloc.o pci.o \
	skip_spaces.o lib-cmdline.o lib-ctype.o \
	alignedmem.o relocate.o printk.o vsprintf.o

	# include the stub's libfdt dependencies from lib/ when needed
	libfdt-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
	fdt_empty_tree.c fdt_sw.c

	lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
	$(patsubst %.c,lib-%.o,$(libfdt-deps))

	$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
	$(call if_changed_rule,cc_o_c)

	lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \
	screen_info.o efi-stub-entry.o

	lib-$(CONFIG_ARM) += arm32-stub.o
	lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o
	lib-$(CONFIG_X86) += x86-stub.o
	lib-$(CONFIG_X86_64) += x86-5lvl.o
	lib-$(CONFIG_RISCV) += kaslr.o riscv.o riscv-stub.o
	lib-$(CONFIG_LOONGARCH) += loongarch.o loongarch-stub.o

	CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)

	zboot-obj-$(CONFIG_RISCV) := lib-clz_ctz.o lib-ashldi3.o
	lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)

	lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o

	extra-y := $(lib-y)
	lib-y := $(patsubst %.o,%.stub.o,$(lib-y))

	# Even when -mbranch-protection=none is set, Clang will generate a
	# .note.gnu.property for code-less object files (like lib/ctype.c),
	# so work around this by explicitly removing the unwanted section.
	# https://llvm.org/pr46480
	STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property

	STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32
	STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64

	#
	# ARM discards the .data section because it disallows r/w data in the
	# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
	# which are preserved explicitly by the decompressor linker script.
	#
	STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \
	--rename-section .bss=.bss.efistub,load,alloc
	STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS

	#
	# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
	# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
	# So let's apply the __init annotations at the section level, by prefixing
	# the section names directly. This will ensure that even all the inline string
	# literals are covered.
	# The fact that the stub and the kernel proper are essentially the same binary
	# also means that we need to be extra careful to make sure that the stub does
	# not rely on any absolute symbol references, considering that the virtual
	# kernel mapping that the linker uses is not active yet when the stub is
	# executing. So build all C dependencies of the EFI stub into libstub, and do
	# a verification pass to see if any absolute relocations exist in any of the
	# object files.
	#
	STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
	--prefix-symbols=__efistub_
	STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS

	# For RISC-V, we don't need anything special other than arm64. Keep all the
	# symbols in .init section and make sure that no absolute symbols references
	# exist.
	STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
	--prefix-symbols=__efistub_
	STUBCOPY_RELOC-$(CONFIG_RISCV) := -E R_RISCV_HI20\\|R_RISCV_$(BITS)\\|R_RISCV_RELAX

	# For LoongArch, keep all the symbols in .init section and make sure that no
	# absolute symbols references exist.
	STUBCOPY_FLAGS-$(CONFIG_LOONGARCH) += --prefix-alloc-sections=.init \
	--prefix-symbols=__efistub_
	STUBCOPY_RELOC-$(CONFIG_LOONGARCH) := R_LARCH_MARK_LA

	$(obj)/%.stub.o: $(obj)/%.o FORCE
	$(call if_changed,stubcopy)

	#
	# Strip debug sections and some other sections that may legally contain
	# absolute relocations, so that we can inspect the remaining sections for
	# such relocations. If none are found, regenerate the output object, but
	# this time, use objcopy and leave all sections in place.
	#
	quiet_cmd_stubcopy = STUBCPY $@
	cmd_stubcopy = \
	$(STRIP) --strip-debug -o $@ $<; \
	if $(OBJDUMP) -r $@ \| grep $(STUBCOPY_RELOC-y); then \
	echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
	/bin/false; \
	fi; \
	$(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@