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. Add relocation checking for x86 as well to catch non-PC-relative relocations that require runtime processing, since the EFI stub does not do any runtime relocation processing. This will catch, for example, data relocations created by static initializers of pointers. Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx> --- arch/x86/boot/compressed/vmlinux.lds.S | 1 + drivers/firmware/efi/libstub/Makefile | 32 +++++++++++++++++--------- drivers/firmware/efi/libstub/efistub.h | 4 ---- 3 files changed, 22 insertions(+), 15 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 45ffe0822df1..069d117d5451 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -73,13 +73,32 @@ 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-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ --prefix-symbols=__efistub_ STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS +# +# ARM discards the .data section because it disallows r/w data in the +# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub, +# which are preserved explicitly by the decompressor linker script. +# +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-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc +STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32 +STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64 + $(obj)/%.stub.o: $(obj)/%.o FORCE $(call if_changed,stubcopy) @@ -97,12 +116,3 @@ quiet_cmd_stubcopy = STUBCPY $@ /bin/false; \ fi; \ $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ - -# -# ARM discards the .data section because it disallows r/w data in the -# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub, -# which are preserved explicitly by the decompressor linker script. -# -STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ - --rename-section .bss=.bss.efistub,load,alloc -STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS 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); -- 2.25.3
