fd045f6cd9
This adds support for emitting PLTs at module load time for relative
branches that are out of range. This is a prerequisite for KASLR, which
may place the kernel and the modules anywhere in the vmalloc area,
making it more likely that branch target offsets exceed the maximum
range of +/- 128 MB.
In this version, I removed the distinction between relocations against
.init executable sections and ordinary executable sections. The reason
is that it is hardly worth the trouble, given that .init.text usually
does not contain that many far branches, and this version now only
reserves PLT entry space for jump and call relocations against undefined
symbols (since symbols defined in the same module can be assumed to be
within +/- 128 MB)
For example, the mac80211.ko module (which is fairly sizable at ~400 KB)
built with -mcmodel=large gives the following relocation counts:
relocs branches unique !local
.text 3925 3347 518 219
.init.text 11 8 7 1
.exit.text 4 4 4 1
.text.unlikely 81 67 36 17
('unique' means branches to unique type/symbol/addend combos, of which
!local is the subset referring to undefined symbols)
IOW, we are only emitting a single PLT entry for the .init sections, and
we are better off just adding it to the core PLT section instead.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
129 lines
3.6 KiB
Makefile
129 lines
3.6 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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OBJCOPYFLAGS :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
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GZFLAGS :=-9
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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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KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr)
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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KBUILD_CFLAGS += $(call cc-option, -mpc-relative-literal-loads)
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KBUILD_AFLAGS += $(lseinstr)
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ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
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KBUILD_CPPFLAGS += -mbig-endian
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AS += -EB
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LD += -EB
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else
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KBUILD_CPPFLAGS += -mlittle-endian
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AS += -EL
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LD += -EL
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endif
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CHECKFLAGS += -D__aarch64__
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ifeq ($(CONFIG_ARM64_MODULE_CMODEL_LARGE), y)
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KBUILD_CFLAGS_MODULE += -mcmodel=large
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endif
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ifeq ($(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%03x000\n", int(512 * rand())}')
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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 - 3)) - (1 << 61)
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# in 32-bit arithmetic
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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 - 3)) \
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- (1 << (64 - 32 - 3)) )) )
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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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KBUILD_IMAGE := Image.gz
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KBUILD_DTBS := dtbs
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all: $(KBUILD_IMAGE) $(KBUILD_DTBS)
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boot := arch/arm64/boot
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Image: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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Image.%: vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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zinstall install: vmlinux
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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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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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