linux/arch/arm64/Makefile
Alice Ryhl d077242d68 rust: support for shadow call stack sanitizer
Add all of the flags that are needed to support the shadow call stack
(SCS) sanitizer with Rust, and updates Kconfig to allow only
configurations that work.

The -Zfixed-x18 flag is required to use SCS on arm64, and requires rustc
version 1.80.0 or greater. This restriction is reflected in Kconfig.

When CONFIG_DYNAMIC_SCS is enabled, the build will be configured to
include unwind tables in the build artifacts. Dynamic SCS uses the
unwind tables at boot to find all places that need to be patched. The
-Cforce-unwind-tables=y flag ensures that unwind tables are available
for Rust code.

In non-dynamic mode, the -Zsanitizer=shadow-call-stack flag is what
enables the SCS sanitizer. Using this flag requires rustc version 1.82.0
or greater on the targets used by Rust in the kernel. This restriction
is reflected in Kconfig.

It is possible to avoid the requirement of rustc 1.80.0 by using
-Ctarget-feature=+reserve-x18 instead of -Zfixed-x18. However, this flag
emits a warning during the build, so this patch does not add support for
using it and instead requires 1.80.0 or greater.

The dependency is placed on `select HAVE_RUST` to avoid a situation
where enabling Rust silently turns off the sanitizer. Instead, turning
on the sanitizer results in Rust being disabled. We generally do not
want changes to CONFIG_RUST to result in any mitigations being changed
or turned off.

At the time of writing, rustc 1.82.0 only exists via the nightly release
channel. There is a chance that the -Zsanitizer=shadow-call-stack flag
will end up needing 1.83.0 instead, but I think it is small.

Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240829-shadow-call-stack-v7-1-2f62a4432abf@google.com
[ Fixed indentation using spaces. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-09-13 00:03:14 +02:00

247 lines
8.1 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
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 "$$TMP" -,,-DCONFIG_CC_HAS_K_CONSTRAINT=1)
ifeq ($(CONFIG_BROKEN_GAS_INST),y)
$(warning Detected assembler with broken .inst; disassembly will be unreliable)
endif
# The GCC option -ffreestanding is required in order to compile code containing
# ARM/NEON intrinsics in a non C99-compliant environment (such as the kernel)
CC_FLAGS_FPU := -ffreestanding
# Enable <arm_neon.h>
CC_FLAGS_FPU += -isystem $(shell $(CC) -print-file-name=include)
CC_FLAGS_NO_FPU := -mgeneral-regs-only
KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU) \
$(compat_vdso) $(cc_has_k_constraint)
KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
KBUILD_AFLAGS += $(compat_vdso)
KBUILD_RUSTFLAGS += --target=aarch64-unknown-none -Ctarget-feature="-neon"
KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
# Avoid generating .eh_frame* sections.
ifneq ($(CONFIG_UNWIND_TABLES),y)
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n
else
KBUILD_CFLAGS += -fasynchronous-unwind-tables
KBUILD_AFLAGS += -fasynchronous-unwind-tables
KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n
endif
ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
prepare: stack_protector_prepare
stack_protector_prepare: prepare0
$(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg \
-mstack-protector-guard-reg=sp_el0 \
-mstack-protector-guard-offset=$(shell \
awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
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