The EFI zboot code is not built as part of the kernel proper, like the ordinary EFI stub, but still needs access to symbols that are defined only internally in the kernel, and are left unexposed deliberately to avoid creating ABI inadvertently that we're stuck with later. So instead of passing the ordinary Image file to the zboot make rules, create an alternate version Image.zboot that has the code size copied into the header into a field that has meaning in the bare metal boot ABI, but is actually not used anymore, and is always set to 0x0. Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- arch/arm64/boot/Makefile | 23 +++++++++++++++++++- arch/arm64/kernel/image-vars.h | 4 ++++ 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile index c65aee0884103c6f..5d73229604b11061 100644 --- a/arch/arm64/boot/Makefile +++ b/arch/arm64/boot/Makefile @@ -39,8 +39,29 @@ $(obj)/Image.lzo: $(obj)/Image FORCE $(obj)/Image.zst: $(obj)/Image FORCE $(call if_changed,zstd) -EFI_ZBOOT_PAYLOAD := Image +EFI_ZBOOT_PAYLOAD := Image.zboot EFI_ZBOOT_BFD_TARGET := elf64-littleaarch64 EFI_ZBOOT_MACH_TYPE := ARM64 +# +# The EFI zboot logic needs to know the size of the executable region in the +# image, so let's poke that into the text_offset field of the image header of +# the zboot payload, as that field is no longer used and can thus be repurposed +# for other, purely internal uses. +# +quiet_cmd_copy_and_poke = $(quiet_cmd_objcopy) + cmd_copy_and_poke = $(cmd_objcopy) && /bin/echo -ne "$(POKE_DATA)" | dd bs=1 \ + status=none conv=notrunc seek=$(POKE_OFFSET) of=$@ + +# grab the code size and convert it into something we can echo +$(obj)/$(EFI_ZBOOT_PAYLOAD): POKE_DATA = $(shell $(NM) $<|grep _kernel_codesize|\ + sed -E 's/0+(..)(..)(..)(..) .+/\\x\4\\x\3\\x\2\\x\1/') +$(obj)/$(EFI_ZBOOT_PAYLOAD): POKE_OFFSET := 8 +$(obj)/$(EFI_ZBOOT_PAYLOAD): vmlinux FORCE + $(call if_changed,copy_and_poke) + +OBJCOPYFLAGS_$(EFI_ZBOOT_PAYLOAD) := $(OBJCOPYFLAGS_Image) + +targets += $(EFI_ZBOOT_PAYLOAD) + include $(srctree)/drivers/firmware/efi/libstub/Makefile.zboot diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h index 8309197c0ebd4a8e..35f3c79595137354 100644 --- a/arch/arm64/kernel/image-vars.h +++ b/arch/arm64/kernel/image-vars.h @@ -108,4 +108,8 @@ KVM_NVHE_ALIAS(kvm_protected_mode_initialized); #endif /* CONFIG_KVM */ +#ifdef CONFIG_EFI_ZBOOT +_kernel_codesize = ABSOLUTE(__inittext_end - _text); +#endif + #endif /* __ARM64_KERNEL_IMAGE_VARS_H */ -- 2.39.2
