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03adcbd996
linux/arch/arm64/Makefile
Will Deacon 03adcbd996 arm64: atomics: Use K constraint when toolchain appears to support it 
The 'K' constraint is a documented AArch64 machine constraint supported
by GCC for matching integer constants that can be used with a 32-bit
logical instruction. Unfortunately, some released compilers erroneously
accept the immediate '4294967295' for this constraint, which is later
refused by GAS at assembly time. This had led us to avoid the use of
the 'K' constraint altogether.

Instead, detect whether the compiler is up to the job when building the
kernel and pass the 'K' constraint to our 32-bit atomic macros when it
appears to be supported.

Signed-off-by: Will Deacon <will@kernel.org>
2019-08-30 11:18:40 +01:00

202 lines
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Makefile
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#
# 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 :=--no-undefined -X
CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
GZFLAGS :=-9
ifeq ($(CONFIG_RELOCATABLE), y)
# Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
# for relative relocs, since this leads to better Image compression
# with the relocation offsets always being zero.
LDFLAGS_vmlinux += -shared -Bsymbolic -z notext -z norelro \
$(call ld-option, --no-apply-dynamic-relocs)
endif
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifeq ($(call ld-option, --fix-cortex-a53-843419),)
$(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
else
LDFLAGS_vmlinux += --fix-cortex-a53-843419
endif
endif
# Check for binutils support for specific extensions
lseinstr := $(call as-instr,.arch_extension lse,-DCONFIG_AS_LSE=1)
ifeq ($(CONFIG_ARM64_LSE_ATOMICS), y)
ifeq ($(lseinstr),)
$(warning LSE atomics not supported by binutils)
endif
endif
cc_has_k_constraint := $(call try-run,echo \
'int main(void) { \
asm volatile("and w0, w0, %w0" :: "K" (4294967295)); \
return 0; \
}' | $(CC) -S -x c -o "$$TMP" -,,-DCONFIG_CC_HAS_K_CONSTRAINT=1)
ifeq ($(CONFIG_ARM64), y)
brokengasinst := $(call as-instr,1:\n.inst 0\n.rept . - 1b\n\nnop\n.endr\n,,-DCONFIG_BROKEN_GAS_INST=1)
ifneq ($(brokengasinst),)
$(warning Detected assembler with broken .inst; disassembly will be unreliable)
endif
endif
ifeq ($(CONFIG_GENERIC_COMPAT_VDSO), y)
CROSS_COMPILE_COMPAT ?= $(CONFIG_CROSS_COMPILE_COMPAT_VDSO:"%"=%)
ifeq ($(CONFIG_CC_IS_CLANG), y)
$(warning CROSS_COMPILE_COMPAT is clang, the compat vDSO will not be built)
else ifeq ($(strip $(CROSS_COMPILE_COMPAT)),)
$(warning CROSS_COMPILE_COMPAT not defined or empty, the compat vDSO will not be built)
else ifeq ($(shell which $(CROSS_COMPILE_COMPAT)gcc 2> /dev/null),)
$(error $(CROSS_COMPILE_COMPAT)gcc not found, check CROSS_COMPILE_COMPAT)
else
export CROSS_COMPILE_COMPAT
export CONFIG_COMPAT_VDSO := y
compat_vdso := -DCONFIG_COMPAT_VDSO=1
endif
endif
KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst) \
$(compat_vdso) $(cc_has_k_constraint)
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) $(compat_vdso)
KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
prepare: stack_protector_prepare
stack_protector_prepare: prepare0
$(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg \
-mstack-protector-guard-reg=sp_el0 \
-mstack-protector-guard-offset=$(shell \
awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
include/generated/asm-offsets.h))
endif
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
CHECKFLAGS += -D__AARCH64EB__
AS += -EB
# Prefer the baremetal ELF build target, but not all toolchains include
# it so fall back to the standard linux version if needed.
KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
UTS_MACHINE := aarch64_be
else
KBUILD_CPPFLAGS += -mlittle-endian
CHECKFLAGS += -D__AARCH64EL__
AS += -EL
# Same as above, prefer ELF but fall back to linux target if needed.
KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux)
UTS_MACHINE := aarch64
endif
CHECKFLAGS += -D__aarch64__
ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds
endif
# Default value
head-y := arch/arm64/kernel/head.o
# The byte offset of the kernel image in RAM from the start of RAM.
ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y)
TEXT_OFFSET := $(shell awk "BEGIN {srand(); printf \"0x%06x\n\", \
int(2 * 1024 * 1024 / (2 ^ $(CONFIG_ARM64_PAGE_SHIFT)) * \
rand()) * (2 ^ $(CONFIG_ARM64_PAGE_SHIFT))}")
else
TEXT_OFFSET := 0x00080000
endif
ifeq ($(CONFIG_KASAN_SW_TAGS), y)
KASAN_SHADOW_SCALE_SHIFT := 4
else
KASAN_SHADOW_SCALE_SHIFT := 3
endif
KBUILD_CFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
KBUILD_CPPFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT))
# - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT))
# in 32-bit arithmetic
KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \
(0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 32))) \
+ (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \
- (1 << (64 - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) )) )
export TEXT_OFFSET GZFLAGS
core-y += arch/arm64/kernel/ arch/arm64/mm/
core-$(CONFIG_NET) += arch/arm64/net/
core-$(CONFIG_KVM) += arch/arm64/kvm/
core-$(CONFIG_XEN) += arch/arm64/xen/
core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
libs-y := arch/arm64/lib/ $(libs-y)
core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
# Default target when executing plain make
boot := arch/arm64/boot
KBUILD_IMAGE := $(boot)/Image.gz
all: Image.gz
Image: vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
Image.%: Image
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
zinstall install:
$(Q)$(MAKE) $(build)=$(boot) $@
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)
ifeq ($(KBUILD_EXTMOD),)
# We need to generate vdso-offsets.h before compiling certain files in kernel/.
# In order to do that, we should use the archprepare target, but we can't since
# asm-offsets.h is included in some files used to generate vdso-offsets.h, and
# asm-offsets.h is built in prepare0, for which archprepare is a dependency.
# Therefore we need to generate the header after prepare0 has been made, hence
# this hack.
prepare: vdso_prepare
vdso_prepare: prepare0
$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h
$(if $(CONFIG_COMPAT_VDSO),$(Q)$(MAKE) \
$(build)=arch/arm64/kernel/vdso32 \
include/generated/vdso32-offsets.h)
endif
define archhelp
echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
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
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