846cfbeed0
The kernel builds with -fno-PIE, so commit 883354afbc ("um: link
vmlinux with -no-pie") added the compiler linker flag '-no-pie' via
cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer.
While this works for GCC, this does not work for clang because cc-option
uses '-c', which stops the pipeline right before linking, so '-no-pie'
is unconsumed and clang warns, causing cc-option to fail just as it
would if the option was entirely unsupported:
$ clang -Werror -no-pie -c -o /dev/null -x c /dev/null
clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument]
A recent version of clang exposes this because it generates a relocation
under '-mcmodel=large' that is not supported in PIE mode:
/usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE
/usr/sbin/ld: failed to set dynamic section sizes: bad value
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Remove the cc-option check altogether. It is wasteful to invoke the
compiler to check for '-no-pie' because only one supported compiler
version does not support it, GCC 5.x (as it is supported with the
minimum version of clang and GCC 6.1.0+). Use a combination of the
gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add
'-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all
compilers that support this. Furthermore, using gcc-min-version can help
turn this back into
LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie
when the minimum version of GCC is bumped past 6.1.0.
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/1982
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
156 lines
5.0 KiB
Makefile
156 lines
5.0 KiB
Makefile
#
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# This file is included by the global makefile so that you can add your own
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# architecture-specific flags and dependencies.
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#
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# Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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# Licensed under the GPL
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#
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# select defconfig based on actual architecture
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ifeq ($(SUBARCH),x86)
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ifeq ($(shell uname -m),x86_64)
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KBUILD_DEFCONFIG := x86_64_defconfig
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else
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KBUILD_DEFCONFIG := i386_defconfig
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endif
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else
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KBUILD_DEFCONFIG := $(SUBARCH)_defconfig
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endif
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ARCH_DIR := arch/um
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# We require bash because the vmlinux link and loader script cpp use bash
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# features.
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SHELL := /bin/bash
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MODE_INCLUDE += -I$(srctree)/$(ARCH_DIR)/include/shared/skas
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HEADER_ARCH := $(SUBARCH)
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ifneq ($(filter $(SUBARCH),x86 x86_64 i386),)
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HEADER_ARCH := x86
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endif
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ifdef CONFIG_64BIT
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KBUILD_CFLAGS += -mcmodel=large
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endif
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HOST_DIR := arch/$(HEADER_ARCH)
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include $(srctree)/$(ARCH_DIR)/Makefile-skas
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include $(srctree)/$(HOST_DIR)/Makefile.um
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core-y += $(HOST_DIR)/um/
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SHARED_HEADERS := $(ARCH_DIR)/include/shared
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ARCH_INCLUDE := -I$(srctree)/$(SHARED_HEADERS)
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ARCH_INCLUDE += -I$(srctree)/$(HOST_DIR)/um/shared
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KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um
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# -Dvmap=kernel_vmap prevents anything from referencing the libpcap.o symbol so
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# named - it's a common symbol in libpcap, so we get a binary which crashes.
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#
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# Same things for in6addr_loopback and mktime - found in libc. For these two we
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# only get link-time error, luckily.
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#
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# -Dlongjmp=kernel_longjmp prevents anything from referencing the libpthread.a
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# embedded copy of longjmp, same thing for setjmp.
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#
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# These apply to USER_CFLAGS to.
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KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
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$(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap \
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-Dlongjmp=kernel_longjmp -Dsetjmp=kernel_setjmp \
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-Din6addr_loopback=kernel_in6addr_loopback \
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-Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr
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KBUILD_RUSTFLAGS += -Crelocation-model=pie
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KBUILD_AFLAGS += $(ARCH_INCLUDE)
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USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
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$(ARCH_INCLUDE) $(MODE_INCLUDE) $(filter -I%,$(CFLAGS)) \
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-D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \
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-idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__
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#This will adjust *FLAGS accordingly to the platform.
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include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux
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KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/include \
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-I$(srctree)/$(HOST_DIR)/include/uapi \
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-I$(objtree)/$(HOST_DIR)/include/generated \
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-I$(objtree)/$(HOST_DIR)/include/generated/uapi
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# -Derrno=kernel_errno - This turns all kernel references to errno into
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# kernel_errno to separate them from the libc errno. This allows -fno-common
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# in KBUILD_CFLAGS. Otherwise, it would cause ld to complain about the two different
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# errnos.
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# These apply to kernelspace only.
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#
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# strip leading and trailing whitespace to make the USER_CFLAGS removal of these
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# defines more robust
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KERNEL_DEFINES = $(strip -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \
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-Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES))
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KBUILD_CFLAGS += $(KERNEL_DEFINES)
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PHONY += linux
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all: linux
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linux: vmlinux
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@echo ' LINK $@'
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$(Q)ln -f $< $@
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define archhelp
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echo '* linux - Binary kernel image (./linux) - for backward'
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echo ' compatibility only, this creates a hard link to the'
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echo ' real kernel binary, the "vmlinux" binary you'
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echo ' find in the kernel root.'
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endef
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archheaders:
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$(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) asm-generic archheaders
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archprepare:
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$(Q)$(MAKE) $(build)=$(HOST_DIR)/um include/generated/user_constants.h
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LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static
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ifdef CONFIG_LD_SCRIPT_DYN
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LINK-$(call gcc-min-version, 60100)$(CONFIG_CC_IS_CLANG) += -no-pie
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endif
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LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib
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CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,) \
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-fno-stack-protector $(call cc-option, -fno-stack-protector-all)
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# Options used by linker script
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export LDS_START := $(START)
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export LDS_ELF_ARCH := $(ELF_ARCH)
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export LDS_ELF_FORMAT := $(ELF_FORMAT)
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# The wrappers will select whether using "malloc" or the kernel allocator.
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LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc
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# Avoid binutils 2.39+ warnings by marking the stack non-executable and
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# ignorning warnings for the kallsyms sections.
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LDFLAGS_EXECSTACK = -z noexecstack
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ifeq ($(CONFIG_LD_IS_BFD),y)
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LDFLAGS_EXECSTACK += $(call ld-option,--no-warn-rwx-segments)
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endif
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LD_FLAGS_CMDLINE = $(foreach opt,$(KBUILD_LDFLAGS) $(LDFLAGS_EXECSTACK),-Wl,$(opt))
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# Used by link-vmlinux.sh which has special support for um link
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export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) $(CC_FLAGS_LTO)
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# When cleaning we don't include .config, so we don't include
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# TT or skas makefiles and don't clean skas_ptregs.h.
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CLEAN_FILES += linux x.i gmon.out
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MRPROPER_FILES += $(HOST_DIR)/include/generated
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archclean:
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@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \
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-o -name '*.gcov' \) -type f -print | xargs rm -f
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export HEADER_ARCH SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING DEV_NULL_PATH
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