mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-03-22 07:27:12 +08:00
5ff8ad3909
This is a follow up to commit c4781dc3d1 ("Kbuild: enable
-fms-extensions") but in a separate change due to being substantially
different from the initial submission.
There are many places within the kernel that use their own CFLAGS
instead of the main KBUILD_CFLAGS, meaning code written with the main
kernel's use of '-fms-extensions' in mind that may be tangentially
included in these areas will result in "error: declaration does not
declare anything" messages from the compiler.
Add '-fms-extensions' to all these areas to ensure consistency, along
with -Wno-microsoft-anon-tag to silence clang's warning about use of the
extension that the kernel cares about using. parisc does not build with
clang so it does not need this warning flag. LoongArch does not need it
either because -W flags from KBUILD_FLAGS are pulled into cflags-vdso.
Reported-by: Christian Brauner <brauner@kernel.org>
Closes: https://lore.kernel.org/20251030-meerjungfrau-getrocknet-7b46eacc215d@brauner/
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
367 lines
12 KiB
Makefile
367 lines
12 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# Unified Makefile for i386 and x86_64
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# select defconfig based on actual architecture
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ifeq ($(ARCH),x86)
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ifeq ($(shell uname -m | sed -e 's/i.86/i386/'),i386)
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KBUILD_DEFCONFIG := i386_defconfig
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else
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KBUILD_DEFCONFIG := x86_64_defconfig
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endif
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else
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KBUILD_DEFCONFIG := $(ARCH)_defconfig
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endif
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ifdef CONFIG_CC_IS_GCC
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RETPOLINE_CFLAGS := -mindirect-branch=thunk-extern -mindirect-branch-register
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RETPOLINE_VDSO_CFLAGS := -mindirect-branch=thunk-inline -mindirect-branch-register
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endif
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ifdef CONFIG_CC_IS_CLANG
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RETPOLINE_CFLAGS := -mretpoline-external-thunk
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RETPOLINE_VDSO_CFLAGS := -mretpoline
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endif
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RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch-cs-prefix)
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ifdef CONFIG_MITIGATION_RETHUNK
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RETHUNK_CFLAGS := -mfunction-return=thunk-extern
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RETHUNK_RUSTFLAGS := -Zfunction-return=thunk-extern
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RETPOLINE_CFLAGS += $(RETHUNK_CFLAGS)
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RETPOLINE_RUSTFLAGS += $(RETHUNK_RUSTFLAGS)
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endif
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export RETHUNK_CFLAGS
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export RETHUNK_RUSTFLAGS
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export RETPOLINE_CFLAGS
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export RETPOLINE_RUSTFLAGS
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export RETPOLINE_VDSO_CFLAGS
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# For gcc stack alignment is specified with -mpreferred-stack-boundary,
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# clang has the option -mstack-alignment for that purpose.
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ifdef CONFIG_CC_IS_GCC
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cc_stack_align4 := -mpreferred-stack-boundary=2
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cc_stack_align8 := -mpreferred-stack-boundary=3
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endif
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ifdef CONFIG_CC_IS_CLANG
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cc_stack_align4 := -mstack-alignment=4
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cc_stack_align8 := -mstack-alignment=8
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endif
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# How to compile the 16-bit code. Note we always compile for -march=i386;
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# that way we can complain to the user if the CPU is insufficient.
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REALMODE_CFLAGS := -std=gnu11 -fms-extensions -m16 -g -Os \
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-DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
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-Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
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-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
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-mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
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REALMODE_CFLAGS += -ffreestanding
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REALMODE_CFLAGS += -fno-stack-protector
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REALMODE_CFLAGS += -Wno-address-of-packed-member
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REALMODE_CFLAGS += $(cc_stack_align4)
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REALMODE_CFLAGS += $(CLANG_FLAGS)
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ifdef CONFIG_CC_IS_CLANG
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REALMODE_CFLAGS += -Wno-gnu
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REALMODE_CFLAGS += -Wno-microsoft-anon-tag
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endif
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export REALMODE_CFLAGS
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# BITS is used as extension for files which are available in a 32 bit
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# and a 64 bit version to simplify shared Makefiles.
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# e.g.: obj-y += foo_$(BITS).o
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export BITS
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#
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# Prevent GCC from generating any FP code by mistake.
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#
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# This must happen before we try the -mpreferred-stack-boundary, see:
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#
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
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#
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KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
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KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json
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KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
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#
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# CFLAGS for compiling floating point code inside the kernel.
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#
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CC_FLAGS_FPU := -msse -msse2
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ifdef CONFIG_CC_IS_GCC
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CC_FLAGS_FPU += -mhard-float
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endif
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ifeq ($(CONFIG_X86_KERNEL_IBT),y)
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#
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# Kernel IBT has S_CET.NOTRACK_EN=0, as such the compilers must not generate
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# NOTRACK prefixes. Current generation compilers unconditionally employ NOTRACK
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# for jump-tables, as such, disable jump-tables for now.
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#
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# (jump-tables are implicitly disabled by RETPOLINE)
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#
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
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#
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KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
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KBUILD_RUSTFLAGS += -Zcf-protection=branch -Zno-jump-tables
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else
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KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
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endif
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ifeq ($(CONFIG_X86_32),y)
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BITS := 32
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UTS_MACHINE := i386
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CHECKFLAGS += -D__i386__
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KBUILD_AFLAGS += -m32
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KBUILD_CFLAGS += -m32
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KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
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# Never want PIC in a 32-bit kernel, prevent breakage with GCC built
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# with nonstandard options
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KBUILD_CFLAGS += -fno-pic
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# Align the stack to the register width instead of using the default
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# alignment of 16 bytes. This reduces stack usage and the number of
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# alignment instructions.
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KBUILD_CFLAGS += $(cc_stack_align4)
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# CPU-specific tuning. Anything which can be shared with UML should go here.
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include $(srctree)/arch/x86/Makefile_32.cpu
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KBUILD_CFLAGS += $(cflags-y)
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ifneq ($(call clang-min-version, 160000),y)
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# https://github.com/llvm/llvm-project/issues/53645
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KBUILD_CFLAGS += -ffreestanding
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endif
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percpu_seg := fs
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else
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BITS := 64
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UTS_MACHINE := x86_64
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CHECKFLAGS += -D__x86_64__
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KBUILD_AFLAGS += -m64
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KBUILD_CFLAGS += -m64
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# Align jump targets to 1 byte, not the default 16 bytes:
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KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
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# Pack loops tightly as well:
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KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
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# Don't autogenerate traditional x87 instructions
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KBUILD_CFLAGS += -mno-80387
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KBUILD_CFLAGS += -mno-fp-ret-in-387
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# By default gcc and clang use a stack alignment of 16 bytes for x86.
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# However the standard kernel entry on x86-64 leaves the stack on an
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# 8-byte boundary. If the compiler isn't informed about the actual
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# alignment it will generate extra alignment instructions for the
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# default alignment which keep the stack *mis*aligned.
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# Furthermore an alignment to the register width reduces stack usage
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# and the number of alignment instructions.
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KBUILD_CFLAGS += $(cc_stack_align8)
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# Use -mskip-rax-setup if supported.
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KBUILD_CFLAGS += -mskip-rax-setup
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ifdef CONFIG_X86_NATIVE_CPU
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KBUILD_CFLAGS += -march=native
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KBUILD_RUSTFLAGS += -Ctarget-cpu=native
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else
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KBUILD_CFLAGS += -march=x86-64 -mtune=generic
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KBUILD_RUSTFLAGS += -Ctarget-cpu=x86-64 -Ztune-cpu=generic
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endif
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KBUILD_CFLAGS += -mno-red-zone
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KBUILD_CFLAGS += -mcmodel=kernel
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KBUILD_RUSTFLAGS += -Cno-redzone=y
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KBUILD_RUSTFLAGS += -Ccode-model=kernel
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percpu_seg := gs
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endif
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ifeq ($(CONFIG_STACKPROTECTOR),y)
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ifeq ($(CONFIG_SMP),y)
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KBUILD_CFLAGS += -mstack-protector-guard-reg=$(percpu_seg)
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KBUILD_CFLAGS += -mstack-protector-guard-symbol=__ref_stack_chk_guard
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else
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KBUILD_CFLAGS += -mstack-protector-guard=global
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endif
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endif
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#
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# If the function graph tracer is used with mcount instead of fentry,
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# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
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# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
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#
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ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ifndef CONFIG_HAVE_FENTRY
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ACCUMULATE_OUTGOING_ARGS := 1
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endif
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endif
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ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
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# This compiler flag is not supported by Clang:
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KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
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endif
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# Workaround for a gcc prelease that unfortunately was shipped in a suse release
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KBUILD_CFLAGS += -Wno-sign-compare
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#
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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# Avoid indirect branches in kernel to deal with Spectre
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ifdef CONFIG_MITIGATION_RETPOLINE
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KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
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KBUILD_RUSTFLAGS += $(RETPOLINE_RUSTFLAGS)
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# Additionally, avoid generating expensive indirect jumps which
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# are subject to retpolines for small number of switch cases.
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# LLVM turns off jump table generation by default when under
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# retpoline builds, however, gcc does not for x86. This has
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# only been fixed starting from gcc stable version 8.4.0 and
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# onwards, but not for older ones. See gcc bug #86952.
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ifndef CONFIG_CC_IS_CLANG
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KBUILD_CFLAGS += -fno-jump-tables
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endif
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endif
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ifdef CONFIG_MITIGATION_SLS
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KBUILD_CFLAGS += -mharden-sls=all
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endif
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ifdef CONFIG_CALL_PADDING
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PADDING_CFLAGS := -fpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
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KBUILD_CFLAGS += $(PADDING_CFLAGS)
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export PADDING_CFLAGS
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PADDING_RUSTFLAGS := -Zpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
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KBUILD_RUSTFLAGS += $(PADDING_RUSTFLAGS)
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export PADDING_RUSTFLAGS
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endif
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KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
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#
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# The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
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# the linker to force 2MB page size regardless of the default page size used
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# by the linker.
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#
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ifdef CONFIG_X86_64
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LDFLAGS_vmlinux += -z max-page-size=0x200000
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endif
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archscripts: scripts_basic
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$(Q)$(MAKE) $(build)=arch/x86/tools relocs
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###
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# Syscall table generation
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archheaders:
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$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
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###
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# <asm/cpufeaturemasks.h> header generation
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cpufeaturemasks.hdr := arch/x86/include/generated/asm/cpufeaturemasks.h
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cpufeaturemasks.awk := $(srctree)/arch/x86/tools/cpufeaturemasks.awk
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cpufeatures_hdr := $(srctree)/arch/x86/include/asm/cpufeatures.h
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targets += $(cpufeaturemasks.hdr)
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filechk_gen_featuremasks = $(AWK) -f $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG)
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$(cpufeaturemasks.hdr): $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) FORCE
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$(shell mkdir -p $(dir $@))
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$(call filechk,gen_featuremasks)
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archprepare: $(cpufeaturemasks.hdr)
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###
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# Kernel objects
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libs-y += arch/x86/lib/
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# drivers-y are linked after core-y
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drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
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drivers-$(CONFIG_PCI) += arch/x86/pci/
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# suspend and hibernation support
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drivers-$(CONFIG_PM) += arch/x86/power/
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drivers-$(CONFIG_VIDEO) += arch/x86/video/
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####
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# boot loader support. Several targets are kept for legacy purposes
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boot := arch/x86/boot
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BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 hdimage isoimage
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PHONY += bzImage $(BOOT_TARGETS)
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# Default kernel to build
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all: bzImage
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# KBUILD_IMAGE specify target image being built
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KBUILD_IMAGE := $(boot)/bzImage
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bzImage: vmlinux
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ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
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$(Q)$(MAKE) $(build)=arch/x86/tools posttest
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endif
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$(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
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$(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
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$(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
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$(BOOT_TARGETS): vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += install
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install:
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$(call cmd,install)
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vdso-install-$(CONFIG_X86_64) += arch/x86/entry/vdso/vdso64.so.dbg
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vdso-install-$(CONFIG_X86_X32_ABI) += arch/x86/entry/vdso/vdsox32.so.dbg
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vdso-install-$(CONFIG_COMPAT_32) += arch/x86/entry/vdso/vdso32.so.dbg
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archprepare: checkbin
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checkbin:
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ifdef CONFIG_MITIGATION_RETPOLINE
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ifeq ($(RETPOLINE_CFLAGS),)
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@echo "You are building kernel with non-retpoline compiler." >&2
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@echo "Please update your compiler." >&2
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@false
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endif
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endif
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ifdef CONFIG_UNWINDER_ORC
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orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
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orc_hash_sh := $(srctree)/scripts/orc_hash.sh
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targets += $(orc_hash_h)
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quiet_cmd_orc_hash = GEN $@
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cmd_orc_hash = mkdir -p $(dir $@); \
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$(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
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$(orc_hash_h): $(srctree)/arch/x86/include/asm/orc_types.h $(orc_hash_sh) FORCE
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$(call if_changed,orc_hash)
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archprepare: $(orc_hash_h)
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endif
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archclean:
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$(Q)rm -rf $(objtree)/arch/i386
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$(Q)rm -rf $(objtree)/arch/x86_64
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define archhelp
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echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
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echo ' install - Install kernel using (your) ~/bin/$(INSTALLKERNEL) or'
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echo ' (distribution) /sbin/$(INSTALLKERNEL) or install to '
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echo ' $$(INSTALL_PATH) and run lilo'
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echo ''
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echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' hdimage - Create a BIOS/EFI hard disk image (arch/x86/boot/hdimage)'
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echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
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echo ' bzdisk/fdimage*/hdimage/isoimage also accept:'
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echo ' FDARGS="..." arguments for the booted kernel'
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echo ' FDINITRD=file initrd for the booted kernel'
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endef
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