a257e02579
Working around Cortex-A53 erratum #843419 involves special handling of ADRP instructions that end up in the last two instruction slots of a 4k page, or whose output register gets overwritten without having been read. (Note that the latter instruction sequence is never emitted by a properly functioning compiler, which is why it is disregarded by the handling of the same erratum in the bfd.ld linker which we rely on for the core kernel) Normally, this gets taken care of by the linker, which can spot such sequences at final link time, and insert a veneer if the ADRP ends up at a vulnerable offset. However, linux kernel modules are partially linked ELF objects, and so there is no 'final link time' other than the runtime loading of the module, at which time all the static relocations are resolved. For this reason, we have implemented the #843419 workaround for modules by avoiding ADRP instructions altogether, by using the large C model, and by passing -mpc-relative-literal-loads to recent versions of GCC that may emit adrp/ldr pairs to perform literal loads. However, this workaround forces us to keep literal data mixed with the instructions in the executable .text segment, and literal data may inadvertently turn into an exploitable speculative gadget depending on the relative offsets of arbitrary symbols. So let's reimplement this workaround in a way that allows us to switch back to the small C model, and to drop the -mpc-relative-literal-loads GCC switch, by patching affected ADRP instructions at runtime: - ADRP instructions that do not appear at 4k relative offset 0xff8 or 0xffc are ignored - ADRP instructions that are within 1 MB of their target symbol are converted into ADR instructions - remaining ADRP instructions are redirected via a veneer that performs the load using an unaffected movn/movk sequence. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [will: tidied up ADRP -> ADR instruction patching.] [will: use ULL suffix for 64-bit immediate] Signed-off-by: Will Deacon <will.deacon@arm.com>
171 lines
5.3 KiB
Makefile
171 lines
5.3 KiB
Makefile
#
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# arch/arm64/Makefile
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#
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# This file is included by the global makefile so that you can add your own
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# architecture-specific flags and dependencies.
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#
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# This file is subject to the terms and conditions of the GNU General Public
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# License. See the file "COPYING" in the main directory of this archive
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# for more details.
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#
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# Copyright (C) 1995-2001 by Russell King
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LDFLAGS_vmlinux :=-p --no-undefined -X
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CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
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GZFLAGS :=-9
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ifeq ($(CONFIG_RELOCATABLE), y)
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# Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
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# for relative relocs, since this leads to better Image compression
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# with the relocation offsets always being zero.
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LDFLAGS_vmlinux += -pie -shared -Bsymbolic \
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$(call ld-option, --no-apply-dynamic-relocs)
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endif
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ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
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ifeq ($(call ld-option, --fix-cortex-a53-843419),)
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$(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
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else
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LDFLAGS_vmlinux += --fix-cortex-a53-843419
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endif
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endif
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KBUILD_DEFCONFIG := defconfig
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# Check for binutils support for specific extensions
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lseinstr := $(call as-instr,.arch_extension lse,-DCONFIG_AS_LSE=1)
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ifeq ($(CONFIG_ARM64_LSE_ATOMICS), y)
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ifeq ($(lseinstr),)
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$(warning LSE atomics not supported by binutils)
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endif
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endif
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ifeq ($(CONFIG_ARM64), y)
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brokengasinst := $(call as-instr,1:\n.inst 0\n.rept . - 1b\n\nnop\n.endr\n,,-DCONFIG_BROKEN_GAS_INST=1)
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ifneq ($(brokengasinst),)
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$(warning Detected assembler with broken .inst; disassembly will be unreliable)
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endif
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endif
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KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst)
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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KBUILD_AFLAGS += $(lseinstr) $(brokengasinst)
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KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
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KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
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KBUILD_CFLAGS += $(call cc-ifversion, -ge, 0500, -DCONFIG_ARCH_SUPPORTS_INT128)
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ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
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KBUILD_CPPFLAGS += -mbig-endian
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CHECKFLAGS += -D__AARCH64EB__
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AS += -EB
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LD += -EB
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LDFLAGS += -maarch64linuxb
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UTS_MACHINE := aarch64_be
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else
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KBUILD_CPPFLAGS += -mlittle-endian
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CHECKFLAGS += -D__AARCH64EL__
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AS += -EL
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LD += -EL
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LDFLAGS += -maarch64linux
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UTS_MACHINE := aarch64
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endif
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CHECKFLAGS += -D__aarch64__ -m64
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ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
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KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds
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endif
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# Default value
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head-y := arch/arm64/kernel/head.o
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# The byte offset of the kernel image in RAM from the start of RAM.
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ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y)
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TEXT_OFFSET := $(shell awk "BEGIN {srand(); printf \"0x%06x\n\", \
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int(2 * 1024 * 1024 / (2 ^ $(CONFIG_ARM64_PAGE_SHIFT)) * \
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rand()) * (2 ^ $(CONFIG_ARM64_PAGE_SHIFT))}")
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else
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TEXT_OFFSET := 0x00080000
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endif
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# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT))
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# - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT))
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# in 32-bit arithmetic
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KASAN_SHADOW_SCALE_SHIFT := 3
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KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \
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(0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 32))) \
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+ (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \
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- (1 << (64 - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) )) )
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export TEXT_OFFSET GZFLAGS
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core-y += arch/arm64/kernel/ arch/arm64/mm/
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core-$(CONFIG_NET) += arch/arm64/net/
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core-$(CONFIG_KVM) += arch/arm64/kvm/
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core-$(CONFIG_XEN) += arch/arm64/xen/
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core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
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libs-y := arch/arm64/lib/ $(libs-y)
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core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
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# Default target when executing plain make
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boot := arch/arm64/boot
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KBUILD_IMAGE := $(boot)/Image.gz
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KBUILD_DTBS := dtbs
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all: Image.gz $(KBUILD_DTBS)
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Image: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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Image.%: Image
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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zinstall install:
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$(Q)$(MAKE) $(build)=$(boot) $@
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%.dtb: scripts
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$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
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PHONY += dtbs dtbs_install
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dtbs: prepare scripts
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$(Q)$(MAKE) $(build)=$(boot)/dts
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dtbs_install:
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$(Q)$(MAKE) $(dtbinst)=$(boot)/dts
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PHONY += vdso_install
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vdso_install:
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso $@
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# We use MRPROPER_FILES and CLEAN_FILES now
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archclean:
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$(Q)$(MAKE) $(clean)=$(boot)
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$(Q)$(MAKE) $(clean)=$(boot)/dts
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# We need to generate vdso-offsets.h before compiling certain files in kernel/.
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# In order to do that, we should use the archprepare target, but we can't since
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# asm-offsets.h is included in some files used to generate vdso-offsets.h, and
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# asm-offsets.h is built in prepare0, for which archprepare is a dependency.
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# Therefore we need to generate the header after prepare0 has been made, hence
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# this hack.
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prepare: vdso_prepare
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vdso_prepare: prepare0
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h
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define archhelp
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echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
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echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
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echo '* dtbs - Build device tree blobs for enabled boards'
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echo ' dtbs_install - Install dtbs to $(INSTALL_DTBS_PATH)'
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echo ' install - Install uncompressed kernel'
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echo ' zinstall - Install compressed kernel'
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echo ' Install using (your) ~/bin/installkernel or'
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echo ' (distribution) /sbin/installkernel or'
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echo ' install to $$(INSTALL_PATH) and run lilo'
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endef
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