95 lines
3.8 KiB
Makefile
95 lines
3.8 KiB
Makefile
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#
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# The stub may be linked into the kernel proper or into a separate boot binary,
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# but in either case, it executes before the kernel does (with MMU disabled) so
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# things like ftrace and stack-protector are likely to cause trouble if left
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# enabled, even if doing so doesn't break the build.
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#
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cflags-$(CONFIG_X86_32) := -march=i386
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cflags-$(CONFIG_X86_64) := -mcmodel=small
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cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
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-fPIC -fno-strict-aliasing -mno-red-zone \
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-mno-mmx -mno-sse
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cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie
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cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \
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-fno-builtin -fpic \
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$(call cc-option,-mno-single-pic-base)
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cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
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KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
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$(call cc-option,-ffreestanding) \
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$(call cc-option,-fno-stack-protector) \
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$(DISABLE_LTO)
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GCOV_PROFILE := n
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KASAN_SANITIZE := n
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UBSAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
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KCOV_INSTRUMENT := n
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lib-y := efi-stub-helper.o gop.o
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# include the stub's generic dependencies from lib/ when building for ARM/arm64
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arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c
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$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
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$(call if_changed_rule,cc_o_c)
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lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \
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$(patsubst %.c,lib-%.o,$(arm-deps))
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lib-$(CONFIG_ARM) += arm32-stub.o
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lib-$(CONFIG_ARM64) += arm64-stub.o random.o
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CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
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#
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# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
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# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
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# So let's apply the __init annotations at the section level, by prefixing
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# the section names directly. This will ensure that even all the inline string
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# literals are covered.
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# The fact that the stub and the kernel proper are essentially the same binary
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# also means that we need to be extra careful to make sure that the stub does
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# not rely on any absolute symbol references, considering that the virtual
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# kernel mapping that the linker uses is not active yet when the stub is
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# executing. So build all C dependencies of the EFI stub into libstub, and do
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# a verification pass to see if any absolute relocations exist in any of the
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# object files.
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#
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extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y)
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lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y))
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STUBCOPY_RM-y := -R *ksymtab* -R *kcrctab*
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STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
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--prefix-symbols=__efistub_
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STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
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$(obj)/%.stub.o: $(obj)/%.o FORCE
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$(call if_changed,stubcopy)
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#
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# Strip debug sections and some other sections that may legally contain
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# absolute relocations, so that we can inspect the remaining sections for
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# such relocations. If none are found, regenerate the output object, but
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# this time, use objcopy and leave all sections in place.
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#
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quiet_cmd_stubcopy = STUBCPY $@
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cmd_stubcopy = if $(STRIP) --strip-debug $(STUBCOPY_RM-y) -o $@ $<; \
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then if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); \
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then (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \
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rm -f $@; /bin/false); \
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else $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; fi \
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else /bin/false; fi
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#
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# ARM discards the .data section because it disallows r/w data in the
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# decompressor. So move our .data to .data.efistub, which is preserved
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# explicitly by the decompressor linker script.
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#
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STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub
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STUBCOPY_RM-$(CONFIG_ARM) += -R ___ksymtab+sort -R ___kcrctab+sort
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STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS
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