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0e470763d8
Pull EFI updates from Ard Biesheuvel:
"A bit more going on than usual in the EFI subsystem. The main driver
for this has been the introduction of the LoonArch architecture last
cycle, which inspired some cleanup and refactoring of the EFI code.
Another driver for EFI changes this cycle and in the future is
confidential compute.
The LoongArch architecture does not use either struct bootparams or DT
natively [yet], and so passing information between the EFI stub and
the core kernel using either of those is undesirable. And in general,
overloading DT has been a source of issues on arm64, so using DT for
this on new architectures is a to avoid for the time being (even if we
might converge on something DT based for non-x86 architectures in the
future). For this reason, in addition to the patch that enables EFI
boot for LoongArch, there are a number of refactoring patches applied
on top of which separate the DT bits from the generic EFI stub bits.
These changes are on a separate topich branch that has been shared
with the LoongArch maintainers, who will include it in their pull
request as well. This is not ideal, but the best way to manage the
conflicts without stalling LoongArch for another cycle.
Another development inspired by LoongArch is the newly added support
for EFI based decompressors. Instead of adding yet another
arch-specific incarnation of this pattern for LoongArch, we are
introducing an EFI app based on the existing EFI libstub
infrastructure that encapulates the decompression code we use on other
architectures, but in a way that is fully generic. This has been
developed and tested in collaboration with distro and systemd folks,
who are eager to start using this for systemd-boot and also for arm64
secure boot on Fedora. Note that the EFI zimage files this introduces
can also be decompressed by non-EFI bootloaders if needed, as the
image header describes the location of the payload inside the image,
and the type of compression that was used. (Note that Fedora's arm64
GRUB is buggy [0] so you'll need a recent version or switch to
systemd-boot in order to use this.)
Finally, we are adding TPM measurement of the kernel command line
provided by EFI. There is an oversight in the TCG spec which results
in a blind spot for command line arguments passed to loaded images,
which means that either the loader or the stub needs to take the
measurement. Given the combinatorial explosion I am anticipating when
it comes to firmware/bootloader stacks and firmware based attestation
protocols (SEV-SNP, TDX, DICE, DRTM), it is good to set a baseline now
when it comes to EFI measured boot, which is that the kernel measures
the initrd and command line. Intermediate loaders can measure
additional assets if needed, but with the baseline in place, we can
deploy measured boot in a meaningful way even if you boot into Linux
straight from the EFI firmware.
Summary:
- implement EFI boot support for LoongArch
- implement generic EFI compressed boot support for arm64, RISC-V and
LoongArch, none of which implement a decompressor today
- measure the kernel command line into the TPM if measured boot is in
effect
- refactor the EFI stub code in order to isolate DT dependencies for
architectures other than x86
- avoid calling SetVirtualAddressMap() on arm64 if the configured
size of the VA space guarantees that doing so is unnecessary
- move some ARM specific code out of the generic EFI source files
- unmap kernel code from the x86 mixed mode 1:1 page tables"
* tag 'efi-next-for-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: (24 commits)
efi/arm64: libstub: avoid SetVirtualAddressMap() when possible
efi: zboot: create MemoryMapped() device path for the parent if needed
efi: libstub: fix up the last remaining open coded boot service call
efi/arm: libstub: move ARM specific code out of generic routines
efi/libstub: measure EFI LoadOptions
efi/libstub: refactor the initrd measuring functions
efi/loongarch: libstub: remove dependency on flattened DT
efi: libstub: install boot-time memory map as config table
efi: libstub: remove DT dependency from generic stub
efi: libstub: unify initrd loading between architectures
efi: libstub: remove pointless goto kludge
efi: libstub: simplify efi_get_memory_map() and struct efi_boot_memmap
efi: libstub: avoid efi_get_memory_map() for allocating the virt map
efi: libstub: drop pointless get_memory_map() call
efi: libstub: fix type confusion for load_options_size
arm64: efi: enable generic EFI compressed boot
loongarch: efi: enable generic EFI compressed boot
riscv: efi: enable generic EFI compressed boot
efi/libstub: implement generic EFI zboot
efi/libstub: move efi_system_table global var into separate object
...
170 lines
6.7 KiB
Makefile
170 lines
6.7 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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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__ \
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-fPIC -fno-strict-aliasing -mno-red-zone \
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-mno-mmx -mno-sse -fshort-wchar \
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-Wno-pointer-sign \
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$(call cc-disable-warning, address-of-packed-member) \
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$(call cc-disable-warning, gnu) \
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-fno-asynchronous-unwind-tables \
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$(CLANG_FLAGS)
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# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
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# disable the stackleak plugin
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cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
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-fpie $(DISABLE_STACKLEAK_PLUGIN) \
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$(call cc-option,-mbranch-protection=none)
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cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(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_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
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-fpic
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cflags-$(CONFIG_LOONGARCH) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
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-fpie
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cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt
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KBUILD_CFLAGS := $(cflags-y) -Os -DDISABLE_BRANCH_PROFILING \
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-include $(srctree)/include/linux/hidden.h \
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-D__NO_FORTIFY \
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-ffreestanding \
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-fno-stack-protector \
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$(call cc-option,-fno-addrsig) \
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-D__DISABLE_EXPORTS
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#
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# struct randomization only makes sense for Linux internal types, which the EFI
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# stub code never touches, so let's turn off struct randomization for the stub
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# altogether
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#
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KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS), $(KBUILD_CFLAGS))
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# remove SCS flags from all objects in this directory
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KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
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# disable CFI
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KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
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# disable LTO
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KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
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GCOV_PROFILE := n
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# Sanitizer runtimes are unavailable and cannot be linked here.
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KASAN_SANITIZE := n
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KCSAN_SANITIZE := n
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UBSAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
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KCOV_INSTRUMENT := n
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lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
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file.o mem.o random.o randomalloc.o pci.o \
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skip_spaces.o lib-cmdline.o lib-ctype.o \
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alignedmem.o relocate.o vsprintf.o
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# include the stub's libfdt dependencies from lib/ when needed
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libfdt-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
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fdt_empty_tree.c fdt_sw.c
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lib-$(CONFIG_EFI_PARAMS_FROM_FDT) += fdt.o \
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$(patsubst %.c,lib-%.o,$(libfdt-deps))
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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-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o
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lib-$(CONFIG_ARM) += arm32-stub.o
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lib-$(CONFIG_ARM64) += arm64-stub.o
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lib-$(CONFIG_X86) += x86-stub.o
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lib-$(CONFIG_RISCV) += riscv-stub.o
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lib-$(CONFIG_LOONGARCH) += loongarch-stub.o
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CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
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zboot-obj-$(CONFIG_RISCV) := lib-clz_ctz.o lib-ashldi3.o
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lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)
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extra-y := $(lib-y)
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lib-y := $(patsubst %.o,%.stub.o,$(lib-y))
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# Even when -mbranch-protection=none is set, Clang will generate a
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# .note.gnu.property for code-less object files (like lib/ctype.c),
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# so work around this by explicitly removing the unwanted section.
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# https://bugs.llvm.org/show_bug.cgi?id=46480
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STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
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#
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# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
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# .bss section, so the .bss section of the EFI stub needs to be included in the
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# .data section of the compressed kernel to ensure initialization. Rename the
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# .bss section here so it's easy to pick out in the linker script.
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#
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STUBCOPY_FLAGS-$(CONFIG_X86) += --rename-section .bss=.bss.efistub,load,alloc
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STUBCOPY_RELOC-$(CONFIG_X86_32) := R_386_32
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STUBCOPY_RELOC-$(CONFIG_X86_64) := R_X86_64_64
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#
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# ARM discards the .data section because it disallows r/w data in the
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# decompressor. So move our .data to .data.efistub and .bss to .bss.efistub,
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# which are preserved explicitly by the decompressor linker script.
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#
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STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \
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--rename-section .bss=.bss.efistub,load,alloc
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STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS
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#
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# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
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# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
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# So let's apply the __init annotations at the section level, by prefixing
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# the section names directly. This will ensure that even all the inline string
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# literals are covered.
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# The fact that the stub and the kernel proper are essentially the same binary
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# also means that we need to be extra careful to make sure that the stub does
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# not rely on any absolute symbol references, considering that the virtual
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# kernel mapping that the linker uses is not active yet when the stub is
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# executing. So build all C dependencies of the EFI stub into libstub, and do
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# a verification pass to see if any absolute relocations exist in any of the
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# object files.
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#
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STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
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--prefix-symbols=__efistub_
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STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
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# For RISC-V, we don't need anything special other than arm64. Keep all the
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# symbols in .init section and make sure that no absolute symbols references
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# doesn't exist.
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STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
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--prefix-symbols=__efistub_
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STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
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# For LoongArch, keep all the symbols in .init section and make sure that no
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# absolute symbols references exist.
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STUBCOPY_FLAGS-$(CONFIG_LOONGARCH) += --prefix-alloc-sections=.init \
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--prefix-symbols=__efistub_
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STUBCOPY_RELOC-$(CONFIG_LOONGARCH) := R_LARCH_MARK_LA
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$(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 $@
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cmd_stubcopy = \
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$(STRIP) --strip-debug -o $@ $<; \
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if $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y); then \
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echo "$@: absolute symbol references not allowed in the EFI stub" >&2; \
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/bin/false; \
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fi; \
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$(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@
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