On Thu, 16 Apr 2020 at 00:15, Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote: > > Instead of using __efistub_global to force variables into the .data > section, leave them in the .bss but pull the EFI stub's .bss section > into .data in the linker script for the compressed kernel. > > Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx> With the R_386_32/R_X86_64_64 check folded in: Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > --- > arch/x86/boot/compressed/vmlinux.lds.S | 1 + > drivers/firmware/efi/libstub/Makefile | 12 ++++++++++-- > drivers/firmware/efi/libstub/efistub.h | 4 ---- > 3 files changed, 11 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S > index 508cfa6828c5..0dc5c2b9614b 100644 > --- a/arch/x86/boot/compressed/vmlinux.lds.S > +++ b/arch/x86/boot/compressed/vmlinux.lds.S > @@ -52,6 +52,7 @@ SECTIONS > _data = . ; > *(.data) > *(.data.*) > + *(.bss.efistub) > _edata = . ; > } > . = ALIGN(L1_CACHE_BYTES); > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index e5e76677f2da..0bb2916eb12b 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -73,8 +73,8 @@ CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > # a verification pass to see if any absolute relocations exist in any of the > # object files. > # > -extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y) > -lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y)) > +extra-y := $(lib-y) > +lib-y := $(patsubst %.o,%.stub.o,$(lib-y)) > > STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ > --prefix-symbols=__efistub_ > @@ -89,6 +89,14 @@ STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ > --rename-section .bss=.bss.efistub,load,alloc > STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS > > +# > +# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the > +# .bss section, so the .bss section of the EFI stub needs to be included in the > +# .data section of the compressed kernel to ensure initialization. Rename the > +# .bss section here so it's easy to pick out in the linker script. > +# > +STUBCOPY_FLAGS-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc > + > $(obj)/%.stub.o: $(obj)/%.o FORCE > $(call if_changed,stubcopy) > > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h > index a92d42ffd9f7..49651e20bb9f 100644 > --- a/drivers/firmware/efi/libstub/efistub.h > +++ b/drivers/firmware/efi/libstub/efistub.h > @@ -25,11 +25,7 @@ > #define EFI_ALLOC_ALIGN EFI_PAGE_SIZE > #endif > > -#if defined(CONFIG_X86) > -#define __efistub_global __section(.data) > -#else > #define __efistub_global > -#endif > > extern bool __pure nochunk(void); > extern bool __pure nokaslr(void); > -- > 2.24.1 >
