drivers/firmware/efi/libstub/Makefile - third_party/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.

            
            #


            cflags-y			:= $(KBUILD_CFLAGS)


            # x86 links the stub into the decompressor rather than the kernel proper, so

            
            # drop the kernel's code model, calling convention, and stack alignment, and

            
            # the mitigations that rely on thunks and patch sites only the kernel has.

            
            cflags-$(CONFIG_X86)		:= $(filter-out -mcmodel=kernel \

            
            				     -mregparm=3 -freg-struct-return \

            
            				     -mpreferred-stack-boundary=% \

            
            				     -mstack-alignment=% \

            
            				     $(RETPOLINE_CFLAGS) $(RETHUNK_CFLAGS) \

            
            				     $(PADDING_CFLAGS), $(cflags-y))

            
            cflags-$(CONFIG_X86_32)		+= -march=i386

            
            cflags-$(CONFIG_X86_64)		+= -mcmodel=small

            
            cflags-$(CONFIG_X86)		+= -fPIC

            
            # Nothing enables IBT while the stub runs, so ENDBR would only take space.

            
            cflags-$(CONFIG_X86)		+= $(call cc-option,-fcf-protection=none)


            cflags-$(CONFIG_ARM64)		+= -fpie -ffixed-x18 -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 \

            
            				   $(DISABLE_KSTACK_ERASE) \

            
            				   $(CONFIG_CC_OPT_NO_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))


            # The .data section would be renamed to .data.efistub, therefore, remove

            
            # `-fdata-sections` flag from KBUILD_CFLAGS_KERNEL

            
            KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNEL))


            KBUILD_AFLAGS			:= $(KBUILD_CFLAGS) -D__ASSEMBLY__


            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 printk.o vsprintf.o bli.o \

            
            				   lib-ucs2_string.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 \

            
            				   primary_display.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 smbios.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-y			:= zboot-decompress-gzip.o

            
            CFLAGS_zboot-decompress-gzip.o	+= -I$(srctree)/lib/zlib_inflate

            
            zboot-obj-$(CONFIG_KERNEL_ZSTD)	:= zboot-decompress-zstd.o lib-xxhash.o

            
            CFLAGS_zboot-decompress-zstd.o	+= -I$(srctree)/lib/zstd


            zboot-riscv-obj-$(CONFIG_32BIT)	:= lib-ashldi3.o lib-lshrdi3.o

            
            zboot-obj-$(CONFIG_RISCV)	+= lib-clz_ctz.o $(zboot-riscv-obj-y)

            
            zboot-loongarch-obj-$(CONFIG_32BIT) := lib-ashldi3.o lib-lshrdi3.o

            
            zboot-obj-$(CONFIG_LOONGARCH)	+= lib-clz_ctz.o $(zboot-loongarch-obj-y)

            
            lib-$(CONFIG_EFI_ZBOOT)		+= zboot.o $(zboot-obj-y)


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


            targets				:= $(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.
	#

	cflags-y := $(KBUILD_CFLAGS)

	# x86 links the stub into the decompressor rather than the kernel proper, so
	# drop the kernel's code model, calling convention, and stack alignment, and
	# the mitigations that rely on thunks and patch sites only the kernel has.
	cflags-$(CONFIG_X86) := $(filter-out -mcmodel=kernel \
	-mregparm=3 -freg-struct-return \
	-mpreferred-stack-boundary=% \
	-mstack-alignment=% \
	$(RETPOLINE_CFLAGS) $(RETHUNK_CFLAGS) \
	$(PADDING_CFLAGS), $(cflags-y))
	cflags-$(CONFIG_X86_32) += -march=i386
	cflags-$(CONFIG_X86_64) += -mcmodel=small
	cflags-$(CONFIG_X86) += -fPIC
	# Nothing enables IBT while the stub runs, so ENDBR would only take space.
	cflags-$(CONFIG_X86) += $(call cc-option,-fcf-protection=none)

	cflags-$(CONFIG_ARM64) += -fpie -ffixed-x18 -fno-unwind-tables \
	-fno-asynchronous-unwind-tables
	cflags-$(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 \
	$(DISABLE_KSTACK_ERASE) \
	$(CONFIG_CC_OPT_NO_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))

	# The .data section would be renamed to .data.efistub, therefore, remove
	# `-fdata-sections` flag from KBUILD_CFLAGS_KERNEL
	KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNEL))

	KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__

	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 printk.o vsprintf.o bli.o \
	lib-ucs2_string.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 \
	primary_display.o efi-stub-entry.o

	lib-$(CONFIG_ARM) += arm32-stub.o
	lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o
	lib-$(CONFIG_X86) += x86-stub.o smbios.o
	lib-$(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-y := zboot-decompress-gzip.o
	CFLAGS_zboot-decompress-gzip.o += -I$(srctree)/lib/zlib_inflate
	zboot-obj-$(CONFIG_KERNEL_ZSTD) := zboot-decompress-zstd.o lib-xxhash.o
	CFLAGS_zboot-decompress-zstd.o += -I$(srctree)/lib/zstd

	zboot-riscv-obj-$(CONFIG_32BIT) := lib-ashldi3.o lib-lshrdi3.o
	zboot-obj-$(CONFIG_RISCV) += lib-clz_ctz.o $(zboot-riscv-obj-y)
	zboot-loongarch-obj-$(CONFIG_32BIT) := lib-ashldi3.o lib-lshrdi3.o
	zboot-obj-$(CONFIG_LOONGARCH) += lib-clz_ctz.o $(zboot-loongarch-obj-y)
	lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)

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

	targets := $(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) $< $@