diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/Makefile')
| -rw-r--r-- | drivers/firmware/efi/libstub/Makefile | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile new file mode 100644 index 000000000..433e11dab --- /dev/null +++ b/drivers/firmware/efi/libstub/Makefile @@ -0,0 +1,149 @@ +# 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__ \ + -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) \ + -fno-asynchronous-unwind-tables \ + $(CLANG_FLAGS) + +# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly +# disable the stackleak plugin +cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ + -fpie $(DISABLE_STACKLEAK_PLUGIN) \ + $(call cc-option,-mbranch-protection=none) +cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ + -fno-builtin -fpic \ + $(call cc-option,-mno-single-pic-base) +cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ + -fpic + +cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt + +KBUILD_CFLAGS := $(cflags-y) -Os -DDISABLE_BRANCH_PROFILING \ + -include $(srctree)/include/linux/hidden.h \ + -D__NO_FORTIFY \ + -ffreestanding \ + -fno-stack-protector \ + $(call cc-option,-fno-addrsig) \ + -D__DISABLE_EXPORTS + +# +# struct randomization only makes sense for Linux internal types, which the EFI +# stub code never touches, so let's turn off struct randomization for the stub +# altogether +# +KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS)) + +# remove SCS flags from all objects in this directory +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS)) + +GCOV_PROFILE := n +# Sanitizer runtimes are unavailable and cannot be linked here. +KASAN_SANITIZE := n +KCSAN_SANITIZE := n +UBSAN_SANITIZE := n +OBJECT_FILES_NON_STANDARD := y + +# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. +KCOV_INSTRUMENT := n + +lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ + file.o mem.o random.o randomalloc.o pci.o \ + skip_spaces.o lib-cmdline.o lib-ctype.o \ + alignedmem.o relocate.o vsprintf.o + +# include the stub's generic dependencies from lib/ when building for ARM/arm64 +efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c + +$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE + $(call if_changed_rule,cc_o_c) + +lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ + $(patsubst %.c,lib-%.o,$(efi-deps-y)) + +lib-$(CONFIG_ARM) += arm32-stub.o +lib-$(CONFIG_ARM64) += arm64-stub.o +lib-$(CONFIG_X86) += x86-stub.o +lib-$(CONFIG_RISCV) += riscv-stub.o +CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) + +# Even when -mbranch-protection=none is set, Clang will generate a +# .note.gnu.property for code-less object files (like lib/ctype.c), +# so work around this by explicitly removing the unwanted section. +# https://bugs.llvm.org/show_bug.cgi?id=46480 +STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property + +# +# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the +# .bss section, so the .bss section of the EFI stub needs to be included in the +# .data section of the compressed kernel to ensure initialization. Rename the +# .bss section here so it's easy to pick out in the linker script. +# +STUBCOPY_FLAGS-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc +STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32 +STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64 + +# +# ARM discards the .data section because it disallows r/w data in the +# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub, +# which are preserved explicitly by the decompressor linker script. +# +STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ + --rename-section .bss=.bss.efistub,load,alloc +STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS + +# +# 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-y := $(lib-y) +lib-y := $(patsubst %.o,%.stub.o,$(lib-y)) + +STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ + --prefix-symbols=__efistub_ +STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS + +# For RISC-V, we don't need anything special other than arm64. Keep all the +# symbols in .init section and make sure that no absolute symbols references +# doesn't exist. +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \ + --prefix-symbols=__efistub_ +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20 + +$(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; \ + $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ |