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linux/arch/arm64/Makefile
Miguel Ojeda 446a8351f1 arm64: rust: clean Rust 1.85.0 warning using softfloat target
Starting with Rust 1.85.0 (to be released 2025-02-20), `rustc` warns
[1] about disabling neon in the aarch64 hardfloat target:

    warning: target feature `neon` cannot be toggled with
             `-Ctarget-feature`: unsound on hard-float targets
             because it changes float ABI
      |
      = note: this was previously accepted by the compiler but
              is being phased out; it will become a hard error
              in a future release!
      = note: for more information, see issue #116344
              <https://github.com/rust-lang/rust/issues/116344>

Thus, instead, use the softfloat target instead.

While trying it out, I found that the kernel sanitizers were not enabled
for that built-in target [2]. Upstream Rust agreed to backport
the enablement for the current beta so that it is ready for
the 1.85.0 release [3] -- thanks!

However, that still means that before Rust 1.85.0, we cannot switch
since sanitizers could be in use. Thus conditionally do so.

Cc: stable@vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is pinned in older LTSs).
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Ralf Jung <post@ralfj.de>
Cc: Jubilee Young <workingjubilee@gmail.com>
Link: https://github.com/rust-lang/rust/pull/133417 [1]
Link: https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/arm64.20neon.20.60-Ctarget-feature.60.20warning/near/495358442 [2]
Link: https://github.com/rust-lang/rust/pull/135905 [3]
Link: https://github.com/rust-lang/rust/issues/116344
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Matthew Maurer <mmaurer@google.com>
Reviewed-by: Ralf Jung <post@ralfj.de>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250210163732.281786-1-ojeda@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2025-02-13 11:45:49 +00:00

250 lines
8.2 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 :=--no-undefined -X --pic-veneer
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 \
$(call ld-option, --no-apply-dynamic-relocs)
endif
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifeq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
LDFLAGS_vmlinux += --fix-cortex-a53-843419
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 "$$TMP" -,,-DCONFIG_CC_HAS_K_CONSTRAINT=1)
ifeq ($(CONFIG_BROKEN_GAS_INST),y)
$(warning Detected assembler with broken .inst; disassembly will be unreliable)
endif
# The GCC option -ffreestanding is required in order to compile code containing
# ARM/NEON intrinsics in a non C99-compliant environment (such as the kernel)
CC_FLAGS_FPU := -ffreestanding
# Enable <arm_neon.h>
CC_FLAGS_FPU += -isystem $(shell $(CC) -print-file-name=include)
CC_FLAGS_NO_FPU := -mgeneral-regs-only
KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU) \
$(compat_vdso) $(cc_has_k_constraint)
KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
KBUILD_AFLAGS += $(compat_vdso)
ifeq ($(call test-ge, $(CONFIG_RUSTC_VERSION), 108500),y)
KBUILD_RUSTFLAGS += --target=aarch64-unknown-none-softfloat
else
KBUILD_RUSTFLAGS += --target=aarch64-unknown-none -Ctarget-feature="-neon"
endif
KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
# Avoid generating .eh_frame* sections.
ifneq ($(CONFIG_UNWIND_TABLES),y)
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n
else
KBUILD_CFLAGS += -fasynchronous-unwind-tables
KBUILD_AFLAGS += -fasynchronous-unwind-tables
KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n
endif
ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
prepare: stack_protector_prepare
stack_protector_prepare: prepare0
$(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg \
-mstack-protector-guard-reg=sp_el0 \
-mstack-protector-guard-offset=$(shell \
awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
$(objtree)/include/generated/asm-offsets.h))
endif
ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
KBUILD_CFLAGS += -mbranch-protection=pac-ret+bti
KBUILD_RUSTFLAGS += -Zbranch-protection=bti,pac-ret
else ifeq ($(CONFIG_ARM64_PTR_AUTH_KERNEL),y)
KBUILD_RUSTFLAGS += -Zbranch-protection=pac-ret
ifeq ($(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET),y)
KBUILD_CFLAGS += -mbranch-protection=pac-ret
else
KBUILD_CFLAGS += -msign-return-address=non-leaf
endif
else
KBUILD_CFLAGS += $(call cc-option,-mbranch-protection=none)
endif
# Tell the assembler to support instructions from the latest target
# architecture.
#
# For non-integrated assemblers we'll pass this on the command line, and for
# integrated assemblers we'll define ARM64_ASM_ARCH and ARM64_ASM_PREAMBLE for
# inline usage.
#
# We cannot pass the same arch flag to the compiler as this would allow it to
# freely generate instructions which are not supported by earlier architecture
# versions, which would prevent a single kernel image from working on earlier
# hardware.
ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
asm-arch := armv8.5-a
else ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
asm-arch := armv8.4-a
else ifeq ($(CONFIG_AS_HAS_ARMV8_3), y)
asm-arch := armv8.3-a
else ifeq ($(CONFIG_AS_HAS_ARMV8_2), y)
asm-arch := armv8.2-a
endif
ifdef asm-arch
KBUILD_CFLAGS += -Wa,-march=$(asm-arch) \
-DARM64_ASM_ARCH='"$(asm-arch)"'
endif
ifeq ($(CONFIG_SHADOW_CALL_STACK), y)
KBUILD_CFLAGS += -ffixed-x18
KBUILD_RUSTFLAGS += -Zfixed-x18
endif
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
CHECKFLAGS += -D__AARCH64EB__
# 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 -z norelro)
UTS_MACHINE := aarch64_be
else
KBUILD_CPPFLAGS += -mlittle-endian
CHECKFLAGS += -D__AARCH64EL__
# Same as above, prefer ELF but fall back to linux target if needed.
KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro)
UTS_MACHINE := aarch64
endif
ifeq ($(CONFIG_LD_IS_LLD), y)
KBUILD_LDFLAGS += -z norelro
endif
CHECKFLAGS += -D__aarch64__
ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS),y)
KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
CC_FLAGS_FTRACE := -fpatchable-function-entry=4,2
else ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_ARGS),y)
KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
CC_FLAGS_FTRACE := -fpatchable-function-entry=2
endif
ifeq ($(CONFIG_KASAN_SW_TAGS), y)
KASAN_SHADOW_SCALE_SHIFT := 4
else ifeq ($(CONFIG_KASAN_GENERIC), y)
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)
libs-y := arch/arm64/lib/ $(libs-y)
libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
# Default target when executing plain make
boot := arch/arm64/boot
BOOT_TARGETS := Image vmlinuz.efi image.fit
PHONY += $(BOOT_TARGETS)
ifeq ($(CONFIG_EFI_ZBOOT),)
KBUILD_IMAGE := $(boot)/Image.gz
else
KBUILD_IMAGE := $(boot)/vmlinuz.efi
endif
all: $(notdir $(KBUILD_IMAGE))
image.fit: dtbs
vmlinuz.efi image.fit: Image
$(BOOT_TARGETS): vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
Image.%: Image
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
ifeq ($(CONFIG_COMPRESSED_INSTALL),y)
DEFAULT_KBUILD_IMAGE = $(KBUILD_IMAGE)
else
DEFAULT_KBUILD_IMAGE = $(boot)/Image
endif
install: KBUILD_IMAGE := $(DEFAULT_KBUILD_IMAGE)
install zinstall:
$(call cmd,install)
archprepare:
$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
@echo "warning: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum" >&2
endif
endif
ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS),y)
ifneq ($(CONFIG_ARM64_LSE_ATOMICS),y)
@echo "warning: LSE atomics not supported by binutils" >&2
endif
endif
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 arch/arm64/kernel/vdso/vdso.so
ifdef CONFIG_COMPAT_VDSO
$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \
arch/arm64/kernel/vdso32/vdso.so
endif
endif
vdso-install-y += arch/arm64/kernel/vdso/vdso.so.dbg
vdso-install-$(CONFIG_COMPAT_VDSO) += arch/arm64/kernel/vdso32/vdso32.so.dbg
include $(srctree)/scripts/Makefile.defconf
PHONY += virtconfig
virtconfig:
$(call merge_into_defconfig_override,defconfig,virt)
define archhelp
echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
echo ' image.fit - Flat Image Tree (arch/$(ARCH)/boot/image.fit)'
echo ' install - Install kernel (compressed if COMPRESSED_INSTALL set)'
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