mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-03-22 07:27:12 +08:00
5ff8ad3909
This is a follow up to commit c4781dc3d1 ("Kbuild: enable
-fms-extensions") but in a separate change due to being substantially
different from the initial submission.
There are many places within the kernel that use their own CFLAGS
instead of the main KBUILD_CFLAGS, meaning code written with the main
kernel's use of '-fms-extensions' in mind that may be tangentially
included in these areas will result in "error: declaration does not
declare anything" messages from the compiler.
Add '-fms-extensions' to all these areas to ensure consistency, along
with -Wno-microsoft-anon-tag to silence clang's warning about use of the
extension that the kernel cares about using. parisc does not build with
clang so it does not need this warning flag. LoongArch does not need it
either because -W flags from KBUILD_FLAGS are pulled into cflags-vdso.
Reported-by: Christian Brauner <brauner@kernel.org>
Closes: https://lore.kernel.org/20251030-meerjungfrau-getrocknet-7b46eacc215d@brauner/
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
173 lines
7.0 KiB
Makefile
173 lines
7.0 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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# non-x86 reuses KBUILD_CFLAGS, x86 does not
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cflags-y := $(KBUILD_CFLAGS)
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cflags-$(CONFIG_X86_32) := -march=i386
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cflags-$(CONFIG_X86_64) := -mcmodel=small
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cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -std=gnu11 -fms-extensions \
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-fPIC -fno-strict-aliasing -mno-red-zone \
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-mno-mmx -mno-sse -fshort-wchar \
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-Wno-pointer-sign \
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$(call cc-disable-warning, address-of-packed-member) \
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$(if $(CONFIG_CC_IS_CLANG),-Wno-gnu -Wno-microsoft-anon-tag) \
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-fno-asynchronous-unwind-tables \
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$(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) += -fpie $(DISABLE_KSTACK_ERASE) \
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-fno-unwind-tables -fno-asynchronous-unwind-tables
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cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
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-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
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-DEFI_HAVE_STRCMP -fno-builtin -fpic \
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$(call cc-option,-mno-single-pic-base) \
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$(DISABLE_KSTACK_ERASE)
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cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax \
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$(DISABLE_KSTACK_ERASE)
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cflags-$(CONFIG_LOONGARCH) += -fpie $(DISABLE_KSTACK_ERASE)
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cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt
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KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \
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-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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# The .data section would be renamed to .data.efistub, therefore, remove
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# `-fdata-sections` flag from KBUILD_CFLAGS_KERNEL
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KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNEL))
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KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
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lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
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file.o mem.o random.o randomalloc.o pci.o \
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skip_spaces.o lib-cmdline.o lib-ctype.o \
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alignedmem.o relocate.o printk.o vsprintf.o
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# include the stub's libfdt dependencies from lib/ when needed
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libfdt-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
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fdt_empty_tree.c fdt_sw.c
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lib-$(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-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \
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screen_info.o efi-stub-entry.o
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lib-$(CONFIG_ARM) += arm32-stub.o
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lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o
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lib-$(CONFIG_X86) += x86-stub.o smbios.o
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lib-$(CONFIG_X86_64) += x86-5lvl.o
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lib-$(CONFIG_RISCV) += kaslr.o riscv.o riscv-stub.o
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lib-$(CONFIG_LOONGARCH) += loongarch.o loongarch-stub.o
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CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
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zboot-obj-y := zboot-decompress-gzip.o
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CFLAGS_zboot-decompress-gzip.o += -I$(srctree)/lib/zlib_inflate
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zboot-obj-$(CONFIG_KERNEL_ZSTD) := zboot-decompress-zstd.o lib-xxhash.o
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CFLAGS_zboot-decompress-zstd.o += -I$(srctree)/lib/zstd
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zboot-obj-$(CONFIG_RISCV) += lib-clz_ctz.o lib-ashldi3.o
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lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)
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lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o
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targets := $(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://llvm.org/pr46480
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STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
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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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# 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) := -E R_RISCV_HI20\|R_RISCV_$(BITS)\|R_RISCV_RELAX
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# For LoongArch, keep all the symbols in .init section and make sure that no
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# absolute symbols references exist.
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STUBCOPY_FLAGS-$(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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