linux/arch/arm64/Makefile
Ard Biesheuvel 4190312beb arm64: align randomized TEXT_OFFSET on 4 kB boundary
When booting via UEFI, the kernel Image is loaded at a 4 kB boundary and
the embedded EFI stub is executed in place. The EFI stub relocates the
Image to reside TEXT_OFFSET bytes above a 2 MB boundary, and jumps into
the kernel proper.

In AArch64, PC relative symbol references are emitted using adrp/add or
adrp/ldr pairs, where the offset into a 4 kB page is resolved using a
separate :lo12: relocation. This implicitly assumes that the code will
always be executed at the same relative offset with respect to a 4 kB
boundary, or the references will point to the wrong address.

This means we should link the kernel at a 4 kB aligned base address in
order to remain compatible with the base address the UEFI loader uses
when doing the initial load of Image. So update the code that generates
TEXT_OFFSET to choose a multiple of 4 kB.

At the same time, update the code so it chooses from the interval [0..2MB)
as the author originally intended.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2014-08-19 19:26:09 +01:00

95 lines
2.6 KiB
Makefile

#
# arch/arm64/Makefile
#
# This file is included by the global makefile so that you can add your own
# architecture-specific flags and dependencies.
#
# This file is subject to the terms and conditions of the GNU General Public
# License. See the file "COPYING" in the main directory of this archive
# for more details.
#
# Copyright (C) 1995-2001 by Russell King
LDFLAGS_vmlinux :=-p --no-undefined -X
CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
OBJCOPYFLAGS :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
GZFLAGS :=-9
LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
KBUILD_DEFCONFIG := defconfig
KBUILD_CFLAGS += -mgeneral-regs-only
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
AS += -EB
LD += -EB
else
KBUILD_CPPFLAGS += -mlittle-endian
AS += -EL
LD += -EL
endif
comma = ,
CHECKFLAGS += -D__aarch64__
# Default value
head-y := arch/arm64/kernel/head.o
# The byte offset of the kernel image in RAM from the start of RAM.
ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y)
TEXT_OFFSET := $(shell awk 'BEGIN {srand(); printf "0x%03x000\n", int(512 * rand())}')
else
TEXT_OFFSET := 0x00080000
endif
export TEXT_OFFSET GZFLAGS
core-y += arch/arm64/kernel/ arch/arm64/mm/
core-$(CONFIG_KVM) += arch/arm64/kvm/
core-$(CONFIG_XEN) += arch/arm64/xen/
core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
libs-y := arch/arm64/lib/ $(libs-y)
libs-y += $(LIBGCC)
libs-$(CONFIG_EFI_STUB) += drivers/firmware/efi/libstub/
# Default target when executing plain make
KBUILD_IMAGE := Image.gz
KBUILD_DTBS := dtbs
all: $(KBUILD_IMAGE) $(KBUILD_DTBS)
boot := arch/arm64/boot
Image Image.gz: vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
zinstall install: vmlinux
$(Q)$(MAKE) $(build)=$(boot) $@
%.dtb: scripts
$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
dtbs: scripts
$(Q)$(MAKE) $(build)=$(boot)/dts dtbs
PHONY += vdso_install
vdso_install:
$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso $@
# We use MRPROPER_FILES and CLEAN_FILES now
archclean:
$(Q)$(MAKE) $(clean)=$(boot)
define archhelp
echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
echo '* dtbs - Build device tree blobs for enabled boards'
echo ' install - Install uncompressed kernel'
echo ' zinstall - Install compressed kernel'
echo ' Install using (your) ~/bin/installkernel or'
echo ' (distribution) /sbin/installkernel or'
echo ' install to $$(INSTALL_PATH) and run lilo'
endef