Commit 45dd403d authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi/zboot: arm64: Inject kernel code size symbol into the zboot payload 



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 capture the kernel code size of the kernel image, and inject it as an
ELF symbol into the object that contains the compressed payload, where
it will be accessible to zboot code that needs it.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
parent 538bc0f4

arch/arm64/boot/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -44,4 +44,7 @@ EFI_ZBOOT_BFD_TARGET := elf64-littleaarch64 
EFI_ZBOOT_MACH_TYPE	:= ARM64

EFI_ZBOOT_FORWARD_CFI	:= $(CONFIG_ARM64_BTI_KERNEL)



EFI_ZBOOT_OBJCOPY_FLAGS	= --add-symbol zboot_code_size=0x$(shell \

				$(NM) vmlinux|grep _kernel_codesize|cut -d' ' -f1)



include $(srctree)/drivers/firmware/efi/libstub/Makefile.zboot

arch/arm64/kernel/image-vars.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */

drivers/firmware/efi/libstub/Makefile.zboot

+1 −1
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ quiet_cmd_compwithsize = $(quiet_cmd_$(zboot-method-y)) 
$(obj)/vmlinuz: $(obj)/vmlinux.bin FORCE

	$(call if_changed,compwithsize)



OBJCOPYFLAGS_vmlinuz.o := -I binary -O $(EFI_ZBOOT_BFD_TARGET) \

OBJCOPYFLAGS_vmlinuz.o := -I binary -O $(EFI_ZBOOT_BFD_TARGET) $(EFI_ZBOOT_OBJCOPY_FLAGS) \

			  --rename-section .data=.gzdata,load,alloc,readonly,contents

$(obj)/vmlinuz.o: $(obj)/vmlinuz FORCE

	$(call if_changed,objcopy)

drivers/firmware/efi/libstub/zboot.lds

+7 −0
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 


ENTRY(__efistub_efi_zboot_header);



PROVIDE(zboot_code_size = ABSOLUTE(0));



SECTIONS

{

	.head : ALIGN(4096) {
@@ -17,6 +19,11 @@ SECTIONS 
		*(.gzdata)

		__efistub__gzdata_end = .;

		*(.rodata* .init.rodata* .srodata*)



		. = ALIGN(4);

		__efistub_code_size = .;

		LONG(zboot_code_size);



		_etext = ALIGN(4096);

		. = _etext;

	}