blob: 0460c7581220e13cc8418488042d9a7bb17c0b3e [file] [log] [blame]
# 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-$(CONFIG_X86_32) := -march=i386
cflags-$(CONFIG_X86_64) := -mcmodel=small
cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 \
-fPIC -fno-strict-aliasing -mno-red-zone \
-mno-mmx -mno-sse -fshort-wchar \
-Wno-pointer-sign \
$(call cc-disable-warning, address-of-packed-member) \
$(call cc-disable-warning, gnu)
# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
# disable the stackleak plugin
cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
$(call cc-option,-ffreestanding) \
$(call cc-option,-fno-stack-protector) \
# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o
# include the stub's generic dependencies from lib/ when building for ARM/arm64
arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
arm-deps-$(CONFIG_ARM64) += 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 random.o \
$(patsubst %.c,lib-%.o,$(arm-deps-y))
lib-$(CONFIG_ARM) += arm32-stub.o
lib-$(CONFIG_ARM64) += arm64-stub.o
# 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-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
$(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; \
# 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