| # |
| # 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-$(CONFIG_X86_32) := -march=i386 |
| cflags-$(CONFIG_X86_64) := -mcmodel=small |
| cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2 \ |
| -fPIC -fno-strict-aliasing -mno-red-zone \ |
| -mno-mmx -mno-sse |
| |
| cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) |
| cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ |
| -fno-builtin -fpic -mno-single-pic-base |
| |
| cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt |
| |
| KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ |
| $(call cc-option,-ffreestanding) \ |
| $(call cc-option,-fno-stack-protector) |
| |
| GCOV_PROFILE := n |
| KASAN_SANITIZE := n |
| UBSAN_SANITIZE := n |
| OBJECT_FILES_NON_STANDARD := y |
| |
| lib-y := efi-stub-helper.o |
| |
| # include the stub's generic dependencies from lib/ when building for ARM/arm64 |
| arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c |
| |
| $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE |
| $(call if_changed_rule,cc_o_c) |
| |
| lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \ |
| $(patsubst %.c,lib-%.o,$(arm-deps)) |
| |
| lib-$(CONFIG_ARM) += arm32-stub.o |
| lib-$(CONFIG_ARM64) += arm64-stub.o |
| CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) |
| |
| # |
| # arm64 puts the stub in the kernel proper, which will unnecessarily retain all |
| # code indefinitely unless it is annotated as __init/__initdata/__initconst etc. |
| # So let's apply the __init annotations at the section level, by prefixing |
| # the section names directly. This will ensure that even all the inline string |
| # literals are covered. |
| # The fact that the stub and the kernel proper are essentially the same binary |
| # also means that we need to be extra careful to make sure that the stub does |
| # not rely on any absolute symbol references, considering that the virtual |
| # kernel mapping that the linker uses is not active yet when the stub is |
| # executing. So build all C dependencies of the EFI stub into libstub, and do |
| # a verification pass to see if any absolute relocations exist in any of the |
| # object files. |
| # |
| extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y) |
| lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y)) |
| |
| STUBCOPY_FLAGS-y := -R .debug* -R *ksymtab* -R *kcrctab* |
| STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ |
| --prefix-symbols=__efistub_ |
| STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS |
| |
| $(obj)/%.stub.o: $(obj)/%.o FORCE |
| $(call if_changed,stubcopy) |
| |
| quiet_cmd_stubcopy = STUBCPY $@ |
| cmd_stubcopy = if $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; then \ |
| $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y) \ |
| && (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \ |
| rm -f $@; /bin/false); else /bin/false; fi |
| |
| # |
| # ARM discards the .data section because it disallows r/w data in the |
| # decompressor. So move our .data to .data.efistub, which is preserved |
| # explicitly by the decompressor linker script. |
| # |
| STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub |
| STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS |