eea673e9d5
For the following assembly code:
.text
.global func
func:
nop
.data
var:
.dword func
When linked with `-pie`, GNU LD populates the `var` variable with the
pre-relocated value of `func`. However, LLVM LLD does not exhibit the
same behavior. This issue also arises with the `kernel_entry` in arch/
loongarch/kernel/head.S:
_head:
.word MZ_MAGIC /* "MZ", MS-DOS header */
.org 0x8
.dword kernel_entry /* Kernel entry point */
The correct kernel entry from the MS-DOS header is crucial for jumping
to vmlinux from zboot. This necessity is why the compressed relocatable
kernel compiled by Clang encounters difficulties in booting.
To address this problem, it is proposed to apply dynamic relocations to
place with `--apply-dynamic-relocs`.
Link: https://github.com/ClangBuiltLinux/linux/issues/1962
Signed-off-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
160 lines
5.2 KiB
Makefile
160 lines
5.2 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Author: Huacai Chen <chenhuacai@loongson.cn>
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# Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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boot := arch/loongarch/boot
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KBUILD_DEFCONFIG := loongson3_defconfig
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image-name-y := vmlinux
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image-name-$(CONFIG_EFI_ZBOOT) := vmlinuz
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ifndef CONFIG_EFI_STUB
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KBUILD_IMAGE := $(boot)/vmlinux.elf
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else
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KBUILD_IMAGE := $(boot)/$(image-name-y).efi
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endif
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#
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# Select the object file format to substitute into the linker script.
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#
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64bit-tool-archpref = loongarch64
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32bit-bfd = elf32-loongarch
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64bit-bfd = elf64-loongarch
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32bit-emul = elf32loongarch
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64bit-emul = elf64loongarch
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ifdef CONFIG_DYNAMIC_FTRACE
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KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
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CC_FLAGS_FTRACE := -fpatchable-function-entry=2
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endif
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ifdef CONFIG_64BIT
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tool-archpref = $(64bit-tool-archpref)
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UTS_MACHINE := loongarch64
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endif
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ifneq ($(SUBARCH),$(ARCH))
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ifeq ($(CROSS_COMPILE),)
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CROSS_COMPILE := $(call cc-cross-prefix, $(tool-archpref)-linux- $(tool-archpref)-linux-gnu- $(tool-archpref)-unknown-linux-gnu-)
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endif
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endif
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ifdef CONFIG_64BIT
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ld-emul = $(64bit-emul)
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cflags-y += -mabi=lp64s
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endif
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cflags-y += -pipe -msoft-float
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LDFLAGS_vmlinux += -static -n -nostdlib
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# When the assembler supports explicit relocation hint, we must use it.
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# GCC may have -mexplicit-relocs off by default if it was built with an old
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# assembler, so we force it via an option.
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#
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# When the assembler does not supports explicit relocation hint, we can't use
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# it. Disable it if the compiler supports it.
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#
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# The combination of a "new" assembler and "old" GCC is not supported, given
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# the rarity of this combo and the extra complexity needed to make it work.
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# Either upgrade the compiler or downgrade the assembler; the build will error
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# out if it is the case (by probing for the model attribute; all supported
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# compilers in this case would have support).
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#
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# Also, -mdirect-extern-access is useful in case of building with explicit
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# relocs, for avoiding unnecessary GOT accesses. It is harmless to not have
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# support though.
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ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
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cflags-y += $(call cc-option,-mexplicit-relocs)
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KBUILD_CFLAGS_KERNEL += $(call cc-option,-mdirect-extern-access)
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KBUILD_CFLAGS_KERNEL += $(call cc-option,-fdirect-access-external-data)
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KBUILD_AFLAGS_MODULE += $(call cc-option,-fno-direct-access-external-data)
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KBUILD_CFLAGS_MODULE += $(call cc-option,-fno-direct-access-external-data)
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KBUILD_AFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
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KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
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else
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cflags-y += $(call cc-option,-mno-explicit-relocs)
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KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
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KBUILD_CFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
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KBUILD_AFLAGS_MODULE += -Wa,-mla-global-with-abs
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KBUILD_CFLAGS_MODULE += -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
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endif
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ifeq ($(CONFIG_RELOCATABLE),y)
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KBUILD_CFLAGS_KERNEL += -fPIE
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LDFLAGS_vmlinux += -static -pie --no-dynamic-linker -z notext $(call ld-option, --apply-dynamic-relocs)
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endif
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cflags-y += $(call cc-option, -mno-check-zero-division)
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ifndef CONFIG_KASAN
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cflags-y += -fno-builtin-memcpy -fno-builtin-memmove -fno-builtin-memset
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endif
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load-y = 0x9000000000200000
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bootvars-y = VMLINUX_LOAD_ADDRESS=$(load-y)
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drivers-$(CONFIG_PCI) += arch/loongarch/pci/
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KBUILD_AFLAGS += $(cflags-y)
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
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# This is required to get dwarf unwinding tables into .debug_frame
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# instead of .eh_frame so we don't discard them.
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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ifdef CONFIG_ARCH_STRICT_ALIGN
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# Don't emit unaligned accesses.
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# Not all LoongArch cores support unaligned access, and as kernel we can't
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# rely on others to provide emulation for these accesses.
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KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
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else
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# Optimise for performance on hardware supports unaligned access.
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KBUILD_CFLAGS += $(call cc-option,-mno-strict-align)
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endif
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KBUILD_CFLAGS += -isystem $(shell $(CC) -print-file-name=include)
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KBUILD_LDFLAGS += -m $(ld-emul)
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ifdef need-compiler
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CHECKFLAGS += $(shell $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -dM -E -x c /dev/null | \
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grep -E -vw '__GNUC_(MINOR_|PATCHLEVEL_)?_' | \
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sed -e "s/^\#define /-D'/" -e "s/ /'='/" -e "s/$$/'/" -e 's/\$$/&&/g')
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endif
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libs-y += arch/loongarch/lib/
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libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
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drivers-y += arch/loongarch/crypto/
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# suspend and hibernation support
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drivers-$(CONFIG_PM) += arch/loongarch/power/
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ifeq ($(KBUILD_EXTMOD),)
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prepare: vdso_prepare
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vdso_prepare: prepare0
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$(Q)$(MAKE) $(build)=arch/loongarch/vdso include/generated/vdso-offsets.h
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endif
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vdso-install-y += arch/loongarch/vdso/vdso.so.dbg
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all: $(notdir $(KBUILD_IMAGE))
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vmlinuz.efi: vmlinux.efi
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vmlinux.elf vmlinux.efi vmlinuz.efi: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $(boot)/$@
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install:
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$(Q)install -D -m 755 $(KBUILD_IMAGE) $(INSTALL_PATH)/$(image-name-y)-$(KERNELRELEASE)
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$(Q)install -D -m 644 .config $(INSTALL_PATH)/config-$(KERNELRELEASE)
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$(Q)install -D -m 644 System.map $(INSTALL_PATH)/System.map-$(KERNELRELEASE)
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define archhelp
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echo ' install - install kernel into $(INSTALL_PATH)'
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echo
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endef
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