| Message ID | 20230426141103.2464423-2-ardb@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Expose kernel code size to EFI zboot code | expand |
On Wed, Apr 26, 2023 at 04:11:02PM +0200, Ard Biesheuvel wrote: > 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: Ard Biesheuvel <ardb@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > arch/arm64/boot/Makefile | 3 +++ > arch/arm64/kernel/image-vars.h | 4 ++++ > drivers/firmware/efi/libstub/Makefile.zboot | 2 +- > drivers/firmware/efi/libstub/zboot.lds | 7 +++++++ > 4 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile > index ae645fda90bca574..1761f5972443fc50 100644 > --- a/arch/arm64/boot/Makefile > +++ b/arch/arm64/boot/Makefile > @@ -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 > 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 */ > diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot > index 0a9dcc2b13736519..1b101d9076fd49e5 100644 > --- a/drivers/firmware/efi/libstub/Makefile.zboot > +++ b/drivers/firmware/efi/libstub/Makefile.zboot > @@ -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) > diff --git a/drivers/firmware/efi/libstub/zboot.lds b/drivers/firmware/efi/libstub/zboot.lds > index 93d33f68333b2b68..ac8c0ef851581f5d 100644 > --- a/drivers/firmware/efi/libstub/zboot.lds > +++ b/drivers/firmware/efi/libstub/zboot.lds > @@ -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; > } > -- > 2.39.2 >
diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile index ae645fda90bca574..1761f5972443fc50 100644 --- a/arch/arm64/boot/Makefile +++ b/arch/arm64/boot/Makefile @@ -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 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 */ diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot index 0a9dcc2b13736519..1b101d9076fd49e5 100644 --- a/drivers/firmware/efi/libstub/Makefile.zboot +++ b/drivers/firmware/efi/libstub/Makefile.zboot @@ -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) diff --git a/drivers/firmware/efi/libstub/zboot.lds b/drivers/firmware/efi/libstub/zboot.lds index 93d33f68333b2b68..ac8c0ef851581f5d 100644 --- a/drivers/firmware/efi/libstub/zboot.lds +++ b/drivers/firmware/efi/libstub/zboot.lds @@ -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; }
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: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/boot/Makefile | 3 +++ arch/arm64/kernel/image-vars.h | 4 ++++ drivers/firmware/efi/libstub/Makefile.zboot | 2 +- drivers/firmware/efi/libstub/zboot.lds | 7 +++++++ 4 files changed, 15 insertions(+), 1 deletion(-)