1f4f75ad5SArd Biesheuvel# 2f4f75ad5SArd Biesheuvel# The stub may be linked into the kernel proper or into a separate boot binary, 3f4f75ad5SArd Biesheuvel# but in either case, it executes before the kernel does (with MMU disabled) so 4f4f75ad5SArd Biesheuvel# things like ftrace and stack-protector are likely to cause trouble if left 5f4f75ad5SArd Biesheuvel# enabled, even if doing so doesn't break the build. 6f4f75ad5SArd Biesheuvel# 7f4f75ad5SArd Biesheuvelcflags-$(CONFIG_X86_32) := -march=i386 8f4f75ad5SArd Biesheuvelcflags-$(CONFIG_X86_64) := -mcmodel=small 9f4f75ad5SArd Biesheuvelcflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2 \ 10f4f75ad5SArd Biesheuvel -fPIC -fno-strict-aliasing -mno-red-zone \ 11f4f75ad5SArd Biesheuvel -mno-mmx -mno-sse -DDISABLE_BRANCH_PROFILING 12f4f75ad5SArd Biesheuvel 13f4f75ad5SArd Biesheuvelcflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) 14f4f75ad5SArd Biesheuvelcflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ 15f4f75ad5SArd Biesheuvel -fno-builtin -fpic -mno-single-pic-base 16f4f75ad5SArd Biesheuvel 17e8f3010fSArd Biesheuvelcflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt 18e8f3010fSArd Biesheuvel 19f4f75ad5SArd BiesheuvelKBUILD_CFLAGS := $(cflags-y) \ 20f4f75ad5SArd Biesheuvel $(call cc-option,-ffreestanding) \ 21f4f75ad5SArd Biesheuvel $(call cc-option,-fno-stack-protector) 22f4f75ad5SArd Biesheuvel 23f4f75ad5SArd BiesheuvelGCOV_PROFILE := n 240b24beccSAndrey RyabininKASAN_SANITIZE := n 25f4f75ad5SArd Biesheuvel 26f4f75ad5SArd Biesheuvellib-y := efi-stub-helper.o 27e8f3010fSArd Biesheuvel 28e8f3010fSArd Biesheuvel# include the stub's generic dependencies from lib/ when building for ARM/arm64 29e8f3010fSArd Biesheuvelarm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c 30e8f3010fSArd Biesheuvel 31e8f3010fSArd Biesheuvel$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE 32e8f3010fSArd Biesheuvel $(call if_changed_rule,cc_o_c) 33e8f3010fSArd Biesheuvel 34e8f3010fSArd Biesheuvellib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \ 35e8f3010fSArd Biesheuvel $(patsubst %.c,lib-%.o,$(arm-deps)) 36f4f75ad5SArd Biesheuvel 37*bf457786SArd Biesheuvellib-$(CONFIG_ARM64) += arm64-stub.o 38*bf457786SArd BiesheuvelCFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) 39*bf457786SArd Biesheuvel 40ddeeefe2SArd Biesheuvel# 41ddeeefe2SArd Biesheuvel# arm64 puts the stub in the kernel proper, which will unnecessarily retain all 42ddeeefe2SArd Biesheuvel# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. 43ddeeefe2SArd Biesheuvel# So let's apply the __init annotations at the section level, by prefixing 44ddeeefe2SArd Biesheuvel# the section names directly. This will ensure that even all the inline string 45ddeeefe2SArd Biesheuvel# literals are covered. 46e8f3010fSArd Biesheuvel# The fact that the stub and the kernel proper are essentially the same binary 47e8f3010fSArd Biesheuvel# also means that we need to be extra careful to make sure that the stub does 48e8f3010fSArd Biesheuvel# not rely on any absolute symbol references, considering that the virtual 49e8f3010fSArd Biesheuvel# kernel mapping that the linker uses is not active yet when the stub is 50e8f3010fSArd Biesheuvel# executing. So build all C dependencies of the EFI stub into libstub, and do 51e8f3010fSArd Biesheuvel# a verification pass to see if any absolute relocations exist in any of the 52e8f3010fSArd Biesheuvel# object files. 53ddeeefe2SArd Biesheuvel# 54e8f3010fSArd Biesheuvelextra-$(CONFIG_EFI_ARMSTUB) := $(lib-y) 55e8f3010fSArd Biesheuvellib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y)) 56ddeeefe2SArd Biesheuvel 57e8f3010fSArd BiesheuvelSTUBCOPY_FLAGS-y := -R .debug* -R *ksymtab* 58e8f3010fSArd BiesheuvelSTUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ 59e8f3010fSArd Biesheuvel --prefix-symbols=__efistub_ 60e8f3010fSArd BiesheuvelSTUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS 61e8f3010fSArd Biesheuvel 62e8f3010fSArd Biesheuvel$(obj)/%.stub.o: $(obj)/%.o FORCE 63e8f3010fSArd Biesheuvel $(call if_changed,stubcopy) 64e8f3010fSArd Biesheuvel 65e8f3010fSArd Biesheuvelquiet_cmd_stubcopy = STUBCPY $@ 66e8f3010fSArd Biesheuvel cmd_stubcopy = if $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; then \ 67e8f3010fSArd Biesheuvel $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y) \ 68e8f3010fSArd Biesheuvel && (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \ 69e8f3010fSArd Biesheuvel rm -f $@; /bin/false); else /bin/false; fi 70