summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/Makefile
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/firmware/efi/libstub/Makefile')
-rw-r--r--drivers/firmware/efi/libstub/Makefile170
1 files changed, 170 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
new file mode 100644
index 000000000..ef5045a53
--- /dev/null
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -0,0 +1,170 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# The stub may be linked into the kernel proper or into a separate boot binary,
+# but in either case, it executes before the kernel does (with MMU disabled) so
+# things like ftrace and stack-protector are likely to cause trouble if left
+# enabled, even if doing so doesn't break the build.
+#
+cflags-$(CONFIG_X86_32) := -march=i386
+cflags-$(CONFIG_X86_64) := -mcmodel=small
+cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \
+ -fPIC -fno-strict-aliasing -mno-red-zone \
+ -mno-mmx -mno-sse -fshort-wchar \
+ -Wno-pointer-sign \
+ $(call cc-disable-warning, address-of-packed-member) \
+ $(call cc-disable-warning, gnu) \
+ -fno-asynchronous-unwind-tables \
+ $(CLANG_FLAGS)
+
+# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
+# disable the stackleak plugin
+cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+ -fpie $(DISABLE_STACKLEAK_PLUGIN) \
+ $(call cc-option,-mbranch-protection=none)
+cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+ -fno-builtin -fpic \
+ $(call cc-option,-mno-single-pic-base)
+cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+ -fpic
+cflags-$(CONFIG_LOONGARCH) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+ -fpie
+
+cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt
+
+KBUILD_CFLAGS := $(cflags-y) -Os -DDISABLE_BRANCH_PROFILING \
+ -include $(srctree)/include/linux/hidden.h \
+ -D__NO_FORTIFY \
+ -ffreestanding \
+ -fno-stack-protector \
+ $(call cc-option,-fno-addrsig) \
+ -D__DISABLE_EXPORTS
+
+#
+# struct randomization only makes sense for Linux internal types, which the EFI
+# stub code never touches, so let's turn off struct randomization for the stub
+# altogether
+#
+KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))
+
+# remove SCS flags from all objects in this directory
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
+# disable CFI
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
+# disable LTO
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
+
+GCOV_PROFILE := n
+# Sanitizer runtimes are unavailable and cannot be linked here.
+KASAN_SANITIZE := n
+KCSAN_SANITIZE := n
+KMSAN_SANITIZE := n
+UBSAN_SANITIZE := n
+OBJECT_FILES_NON_STANDARD := y
+
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT := n
+
+lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
+ file.o mem.o random.o randomalloc.o pci.o \
+ skip_spaces.o lib-cmdline.o lib-ctype.o \
+ alignedmem.o relocate.o vsprintf.o
+
+# include the stub's libfdt dependencies from lib/ when needed
+libfdt-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
+ fdt_empty_tree.c fdt_sw.c
+
+lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
+ $(patsubst %.c,lib-%.o,$(libfdt-deps))
+
+$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
+ $(call if_changed_rule,cc_o_c)
+
+lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o
+
+lib-$(CONFIG_ARM) += arm32-stub.o
+lib-$(CONFIG_ARM64) += arm64-stub.o smbios.o
+lib-$(CONFIG_X86) += x86-stub.o
+lib-$(CONFIG_RISCV) += riscv-stub.o
+lib-$(CONFIG_LOONGARCH) += loongarch-stub.o
+
+CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
+
+zboot-obj-$(CONFIG_RISCV) := lib-clz_ctz.o lib-ashldi3.o
+lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)
+
+extra-y := $(lib-y)
+lib-y := $(patsubst %.o,%.stub.o,$(lib-y))
+
+# Even when -mbranch-protection=none is set, Clang will generate a
+# .note.gnu.property for code-less object files (like lib/ctype.c),
+# so work around this by explicitly removing the unwanted section.
+# https://bugs.llvm.org/show_bug.cgi?id=46480
+STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
+
+#
+# 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-$(CONFIG_X86_64) := R_X86_64_64
+
+#
+# ARM discards the .data section because it disallows r/w data in the
+# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
+# which are preserved explicitly by the decompressor linker script.
+#
+STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \
+ --rename-section .bss=.bss.efistub,load,alloc
+STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS
+
+#
+# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
+# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
+# So let's apply the __init annotations at the section level, by prefixing
+# the section names directly. This will ensure that even all the inline string
+# literals are covered.
+# The fact that the stub and the kernel proper are essentially the same binary
+# also means that we need to be extra careful to make sure that the stub does
+# not rely on any absolute symbol references, considering that the virtual
+# kernel mapping that the linker uses is not active yet when the stub is
+# executing. So build all C dependencies of the EFI stub into libstub, and do
+# a verification pass to see if any absolute relocations exist in any of the
+# object files.
+#
+STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
+ --prefix-symbols=__efistub_
+STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
+
+# For RISC-V, we don't need anything special other than arm64. Keep all the
+# symbols in .init section and make sure that no absolute symbols references
+# doesn't exist.
+STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
+ --prefix-symbols=__efistub_
+STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
+
+# For LoongArch, keep all the symbols in .init section and make sure that no
+# absolute symbols references exist.
+STUBCOPY_FLAGS-$(CONFIG_LOONGARCH) += --prefix-alloc-sections=.init \
+ --prefix-symbols=__efistub_
+STUBCOPY_RELOC-$(CONFIG_LOONGARCH) := R_LARCH_MARK_LA
+
+$(obj)/%.stub.o: $(obj)/%.o FORCE
+ $(call if_changed,stubcopy)
+
+#
+# Strip debug sections and some other sections that may legally contain
+# absolute relocations, so that we can inspect the remaining sections for
+# such relocations. If none are found, regenerate the output object, but
+# this time, use objcopy and leave all sections in place.
+#
+quiet_cmd_stubcopy = STUBCPY $@
+ cmd_stubcopy = \
+ $(STRIP) --strip-debug -o $@ $<; \
+ if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then \
+ echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
+ /bin/false; \
+ fi; \
+ $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@