1# 2# The stub may be linked into the kernel proper or into a separate boot binary, 3# but in either case, it executes before the kernel does (with MMU disabled) so 4# things like ftrace and stack-protector are likely to cause trouble if left 5# enabled, even if doing so doesn't break the build. 6# 7cflags-$(CONFIG_X86_32) := -march=i386 8cflags-$(CONFIG_X86_64) := -mcmodel=small 9cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 \ 10 -fPIC -fno-strict-aliasing -mno-red-zone \ 11 -mno-mmx -mno-sse 12 13cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) 14cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ 15 -fno-builtin -fpic -mno-single-pic-base 16 17cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt 18 19KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ 20 $(call cc-option,-ffreestanding) \ 21 $(call cc-option,-fno-stack-protector) 22 23GCOV_PROFILE := n 24KASAN_SANITIZE := n 25UBSAN_SANITIZE := n 26OBJECT_FILES_NON_STANDARD := y 27 28# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. 29KCOV_INSTRUMENT := n 30 31lib-y := efi-stub-helper.o gop.o secureboot.o 32 33# include the stub's generic dependencies from lib/ when building for ARM/arm64 34arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c 35 36$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE 37 $(call if_changed_rule,cc_o_c) 38 39lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o random.o \ 40 $(patsubst %.c,lib-%.o,$(arm-deps)) 41 42lib-$(CONFIG_ARM) += arm32-stub.o 43lib-$(CONFIG_ARM64) += arm64-stub.o 44CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) 45 46# 47# arm64 puts the stub in the kernel proper, which will unnecessarily retain all 48# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. 49# So let's apply the __init annotations at the section level, by prefixing 50# the section names directly. This will ensure that even all the inline string 51# literals are covered. 52# The fact that the stub and the kernel proper are essentially the same binary 53# also means that we need to be extra careful to make sure that the stub does 54# not rely on any absolute symbol references, considering that the virtual 55# kernel mapping that the linker uses is not active yet when the stub is 56# executing. So build all C dependencies of the EFI stub into libstub, and do 57# a verification pass to see if any absolute relocations exist in any of the 58# object files. 59# 60extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y) 61lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y)) 62 63STUBCOPY_RM-y := -R *ksymtab* -R *kcrctab* 64STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ 65 --prefix-symbols=__efistub_ 66STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS 67 68$(obj)/%.stub.o: $(obj)/%.o FORCE 69 $(call if_changed,stubcopy) 70 71# 72# Strip debug sections and some other sections that may legally contain 73# absolute relocations, so that we can inspect the remaining sections for 74# such relocations. If none are found, regenerate the output object, but 75# this time, use objcopy and leave all sections in place. 76# 77quiet_cmd_stubcopy = STUBCPY $@ 78 cmd_stubcopy = if $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<; \ 79 then if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); \ 80 then (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \ 81 rm -f $@; /bin/false); \ 82 else $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; fi \ 83 else /bin/false; fi 84 85# 86# ARM discards the .data section because it disallows r/w data in the 87# decompressor. So move our .data to .data.efistub, which is preserved 88# explicitly by the decompressor linker script. 89# 90STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub 91STUBCOPY_RM-$(CONFIG_ARM) += -R ___ksymtab+sort -R ___kcrctab+sort 92STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS 93