| Message ID | 20200415221520.2692512-4-nivedita@alum.mit.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | efi: Remove __efistub_global annotation | expand |
On Thu, 16 Apr 2020 at 00:15, Arvind Sankar <nivedita@alum.mit.edu> 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@alum.mit.edu> With the R_386_32/R_X86_64_64 check folded in: Reviewed-by: Ard Biesheuvel <ardb@kernel.org> > --- > 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 > $(call if_changed,stubcopy) > > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h > index a92d42ffd9f7..49651e20bb9f 100644 > --- a/drivers/firmware/efi/libstub/efistub.h > +++ b/drivers/firmware/efi/libstub/efistub.h > @@ -25,11 +25,7 @@ > #define EFI_ALLOC_ALIGN EFI_PAGE_SIZE > #endif > > -#if defined(CONFIG_X86) > -#define __efistub_global __section(.data) > -#else > #define __efistub_global > -#endif > > extern bool __pure nochunk(void); > extern bool __pure nokaslr(void); > -- > 2.24.1 >
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 508cfa6828c5..0dc5c2b9614b 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -52,6 +52,7 @@ SECTIONS _data = . ; *(.data) *(.data.*) + *(.bss.efistub) _edata = . ; } . = ALIGN(L1_CACHE_BYTES); diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index e5e76677f2da..0bb2916eb12b 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -73,8 +73,8 @@ CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(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);
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@alum.mit.edu> --- 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(-)