1b2441318SGreg Kroah-Hartman# SPDX-License-Identifier: GPL-2.0 2f4f75ad5SArd Biesheuvel# 3f4f75ad5SArd Biesheuvel# The stub may be linked into the kernel proper or into a separate boot binary, 4f4f75ad5SArd Biesheuvel# but in either case, it executes before the kernel does (with MMU disabled) so 5f4f75ad5SArd Biesheuvel# things like ftrace and stack-protector are likely to cause trouble if left 6f4f75ad5SArd Biesheuvel# enabled, even if doing so doesn't break the build. 7f4f75ad5SArd Biesheuvel# 8f4f75ad5SArd Biesheuvelcflags-$(CONFIG_X86_32) := -march=i386 9769e0fe1SArd Biesheuvelcflags-$(CONFIG_X86_64) := -mcmodel=small 10bbf8e8b0SArvind Sankarcflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \ 11f4f75ad5SArd Biesheuvel -fPIC -fno-strict-aliasing -mno-red-zone \ 123db5e0baSNathan Chancellor -mno-mmx -mno-sse -fshort-wchar \ 133db5e0baSNathan Chancellor -Wno-pointer-sign \ 143db5e0baSNathan Chancellor $(call cc-disable-warning, address-of-packed-member) \ 15003602adSArvind Sankar $(call cc-disable-warning, gnu) \ 16003602adSArvind Sankar -fno-asynchronous-unwind-tables 17f4f75ad5SArd Biesheuvel 18ce279d37SLaura Abbott# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly 19ce279d37SLaura Abbott# disable the stackleak plugin 20e1a7eafbSTorsten Duwecflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ 21e2179a09SKees Cook -fpie $(DISABLE_STACKLEAK_PLUGIN) \ 22e2179a09SKees Cook $(call cc-option,-mbranch-protection=none) 23e1a7eafbSTorsten Duwecflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ 2441f1c484SAlistair Strachan -fno-builtin -fpic \ 2541f1c484SAlistair Strachan $(call cc-option,-mno-single-pic-base) 26d7071743SAtish Patracflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ 27d7071743SAtish Patra -fpic 28f4f75ad5SArd Biesheuvel 292e0eb483SAtish Patracflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt 30e8f3010fSArd Biesheuvel 31bbf8e8b0SArvind SankarKBUILD_CFLAGS := $(cflags-y) -Os -DDISABLE_BRANCH_PROFILING \ 32e544ea57SArd Biesheuvel -include $(srctree)/include/linux/hidden.h \ 333e2c044aSKees Cook -D__NO_FORTIFY \ 34685969e0SMasahiro Yamada -ffreestanding \ 35893ab004SMasahiro Yamada -fno-stack-protector \ 36f77767edSArd Biesheuvel $(call cc-option,-fno-addrsig) \ 37f922c4abSArd Biesheuvel -D__DISABLE_EXPORTS 38f4f75ad5SArd Biesheuvel 39cc49c71dSSami Tolvanen# remove SCS flags from all objects in this directory 40cc49c71dSSami TolvanenKBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS)) 41*6e20f185SSami Tolvanen# disable LTO 42*6e20f185SSami TolvanenKBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS)) 43cc49c71dSSami Tolvanen 44f4f75ad5SArd BiesheuvelGCOV_PROFILE := n 450ebba714SMarco Elver# Sanitizer runtimes are unavailable and cannot be linked here. 460b24beccSAndrey RyabininKASAN_SANITIZE := n 470ebba714SMarco ElverKCSAN_SANITIZE := n 48c6d30853SAndrey RyabininUBSAN_SANITIZE := n 49c0dd6716SJosh PoimboeufOBJECT_FILES_NON_STANDARD := y 50f4f75ad5SArd Biesheuvel 515c9a8750SDmitry Vyukov# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. 525c9a8750SDmitry VyukovKCOV_INSTRUMENT := n 535c9a8750SDmitry Vyukov 540d959814SDominik Brodowskilib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ 5591d150c0SArd Biesheuvel file.o mem.o random.o randomalloc.o pci.o \ 5643b1df0eSArd Biesheuvel skip_spaces.o lib-cmdline.o lib-ctype.o \ 572c7d1e30SArvind Sankar alignedmem.o relocate.o vsprintf.o 58e8f3010fSArd Biesheuvel 59e8f3010fSArd Biesheuvel# include the stub's generic dependencies from lib/ when building for ARM/arm64 602e0eb483SAtish Patraefi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c 61e8f3010fSArd Biesheuvel 62e8f3010fSArd Biesheuvel$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE 63e8f3010fSArd Biesheuvel $(call if_changed_rule,cc_o_c) 64e8f3010fSArd Biesheuvel 652e0eb483SAtish Patralib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ 662e0eb483SAtish Patra $(patsubst %.c,lib-%.o,$(efi-deps-y)) 67f4f75ad5SArd Biesheuvel 6881a0bc39SRoy Franzlib-$(CONFIG_ARM) += arm32-stub.o 69a6a14469SArd Biesheuvellib-$(CONFIG_ARM64) += arm64-stub.o 70c2d0b470SArd Biesheuvellib-$(CONFIG_X86) += x86-stub.o 71d7071743SAtish Patralib-$(CONFIG_RISCV) += riscv-stub.o 7241cd96faSArd BiesheuvelCFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) 73bf457786SArd Biesheuvel 74e2179a09SKees Cook# Even when -mbranch-protection=none is set, Clang will generate a 75e2179a09SKees Cook# .note.gnu.property for code-less object files (like lib/ctype.c), 76e2179a09SKees Cook# so work around this by explicitly removing the unwanted section. 77e2179a09SKees Cook# https://bugs.llvm.org/show_bug.cgi?id=46480 78e2179a09SKees CookSTUBCOPY_FLAGS-y += --remove-section=.note.gnu.property 79e2179a09SKees Cook 80ddeeefe2SArd Biesheuvel# 8126a92425SArvind Sankar# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the 8226a92425SArvind Sankar# .bss section, so the .bss section of the EFI stub needs to be included in the 8326a92425SArvind Sankar# .data section of the compressed kernel to ensure initialization. Rename the 8426a92425SArvind Sankar# .bss section here so it's easy to pick out in the linker script. 8526a92425SArvind Sankar# 8626a92425SArvind SankarSTUBCOPY_FLAGS-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc 8726a92425SArvind SankarSTUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32 8826a92425SArvind SankarSTUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64 8926a92425SArvind Sankar 9026a92425SArvind Sankar# 9126a92425SArvind Sankar# ARM discards the .data section because it disallows r/w data in the 9226a92425SArvind Sankar# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub, 9326a92425SArvind Sankar# which are preserved explicitly by the decompressor linker script. 9426a92425SArvind Sankar# 9526a92425SArvind SankarSTUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ 9626a92425SArvind Sankar --rename-section .bss=.bss.efistub,load,alloc 9726a92425SArvind SankarSTUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS 9826a92425SArvind Sankar 9926a92425SArvind Sankar# 100ddeeefe2SArd Biesheuvel# arm64 puts the stub in the kernel proper, which will unnecessarily retain all 101ddeeefe2SArd Biesheuvel# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. 102ddeeefe2SArd Biesheuvel# So let's apply the __init annotations at the section level, by prefixing 103ddeeefe2SArd Biesheuvel# the section names directly. This will ensure that even all the inline string 104ddeeefe2SArd Biesheuvel# literals are covered. 105e8f3010fSArd Biesheuvel# The fact that the stub and the kernel proper are essentially the same binary 106e8f3010fSArd Biesheuvel# also means that we need to be extra careful to make sure that the stub does 107e8f3010fSArd Biesheuvel# not rely on any absolute symbol references, considering that the virtual 108e8f3010fSArd Biesheuvel# kernel mapping that the linker uses is not active yet when the stub is 109e8f3010fSArd Biesheuvel# executing. So build all C dependencies of the EFI stub into libstub, and do 110e8f3010fSArd Biesheuvel# a verification pass to see if any absolute relocations exist in any of the 111e8f3010fSArd Biesheuvel# object files. 112ddeeefe2SArd Biesheuvel# 11326a92425SArvind Sankarextra-y := $(lib-y) 11426a92425SArvind Sankarlib-y := $(patsubst %.o,%.stub.o,$(lib-y)) 115ddeeefe2SArd Biesheuvel 116e8f3010fSArd BiesheuvelSTUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ 117e8f3010fSArd Biesheuvel --prefix-symbols=__efistub_ 118e8f3010fSArd BiesheuvelSTUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS 119e8f3010fSArd Biesheuvel 120d7071743SAtish Patra# For RISC-V, we don't need anything special other than arm64. Keep all the 121d7071743SAtish Patra# symbols in .init section and make sure that no absolute symbols references 122d7071743SAtish Patra# doesn't exist. 123d7071743SAtish PatraSTUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \ 124d7071743SAtish Patra --prefix-symbols=__efistub_ 125d7071743SAtish PatraSTUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20 126d7071743SAtish Patra 127e8f3010fSArd Biesheuvel$(obj)/%.stub.o: $(obj)/%.o FORCE 128e8f3010fSArd Biesheuvel $(call if_changed,stubcopy) 129e8f3010fSArd Biesheuvel 130696204faSArd Biesheuvel# 131696204faSArd Biesheuvel# Strip debug sections and some other sections that may legally contain 132696204faSArd Biesheuvel# absolute relocations, so that we can inspect the remaining sections for 133696204faSArd Biesheuvel# such relocations. If none are found, regenerate the output object, but 134696204faSArd Biesheuvel# this time, use objcopy and leave all sections in place. 135696204faSArd Biesheuvel# 136e8f3010fSArd Biesheuvelquiet_cmd_stubcopy = STUBCPY $@ 137e8d368adSMasahiro Yamada cmd_stubcopy = \ 13802562d0cSArd Biesheuvel $(STRIP) --strip-debug -o $@ $<; \ 139e8d368adSMasahiro Yamada if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then \ 140e8d368adSMasahiro Yamada echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \ 141e8d368adSMasahiro Yamada /bin/false; \ 142e8d368adSMasahiro Yamada fi; \ 143e8d368adSMasahiro Yamada $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ 144