1# SPDX-License-Identifier: GPL-2.0 2# 3# The stub may be linked into the kernel proper or into a separate boot binary, 4# but in either case, it executes before the kernel does (with MMU disabled) so 5# things like ftrace and stack-protector are likely to cause trouble if left 6# enabled, even if doing so doesn't break the build. 7# 8cflags-$(CONFIG_X86_32) := -march=i386 9cflags-$(CONFIG_X86_64) := -mcmodel=small 10cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 \ 11 -fPIC -fno-strict-aliasing -mno-red-zone \ 12 -mno-mmx -mno-sse -fshort-wchar 13 14# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly 15# disable the stackleak plugin 16cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie \ 17 $(DISABLE_STACKLEAK_PLUGIN) 18cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \ 19 -fno-builtin -fpic -mno-single-pic-base 20 21cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt 22 23KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ 24 -D__NO_FORTIFY \ 25 $(call cc-option,-ffreestanding) \ 26 $(call cc-option,-fno-stack-protector) \ 27 -D__DISABLE_EXPORTS 28 29GCOV_PROFILE := n 30KASAN_SANITIZE := n 31UBSAN_SANITIZE := n 32OBJECT_FILES_NON_STANDARD := y 33 34# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. 35KCOV_INSTRUMENT := n 36 37lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o 38 39# include the stub's generic dependencies from lib/ when building for ARM/arm64 40arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c 41arm-deps-$(CONFIG_ARM64) += sort.c 42 43$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE 44 $(call if_changed_rule,cc_o_c) 45 46lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o random.o \ 47 $(patsubst %.c,lib-%.o,$(arm-deps-y)) 48 49lib-$(CONFIG_ARM) += arm32-stub.o 50lib-$(CONFIG_ARM64) += arm64-stub.o 51CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) 52 53# 54# arm64 puts the stub in the kernel proper, which will unnecessarily retain all 55# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. 56# So let's apply the __init annotations at the section level, by prefixing 57# the section names directly. This will ensure that even all the inline string 58# literals are covered. 59# The fact that the stub and the kernel proper are essentially the same binary 60# also means that we need to be extra careful to make sure that the stub does 61# not rely on any absolute symbol references, considering that the virtual 62# kernel mapping that the linker uses is not active yet when the stub is 63# executing. So build all C dependencies of the EFI stub into libstub, and do 64# a verification pass to see if any absolute relocations exist in any of the 65# object files. 66# 67extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y) 68lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y)) 69 70STUBCOPY_RM-y := -R *ksymtab* -R *kcrctab* 71STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ 72 --prefix-symbols=__efistub_ 73STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS 74 75$(obj)/%.stub.o: $(obj)/%.o FORCE 76 $(call if_changed,stubcopy) 77 78# 79# Strip debug sections and some other sections that may legally contain 80# absolute relocations, so that we can inspect the remaining sections for 81# such relocations. If none are found, regenerate the output object, but 82# this time, use objcopy and leave all sections in place. 83# 84quiet_cmd_stubcopy = STUBCPY $@ 85 cmd_stubcopy = if $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<; \ 86 then if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); \ 87 then (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \ 88 rm -f $@; /bin/false); \ 89 else $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; fi \ 90 else /bin/false; fi 91 92# 93# ARM discards the .data section because it disallows r/w data in the 94# decompressor. So move our .data to .data.efistub, which is preserved 95# explicitly by the decompressor linker script. 96# 97STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub 98STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS 99