Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1# SPDX-License-Identifier: GPL-2.0
2# Unified Makefile for i386 and x86_64
3
4# select defconfig based on actual architecture
5ifeq ($(ARCH),x86)
6 ifeq ($(shell uname -m | sed -e 's/i.86/i386/'),i386)
7 KBUILD_DEFCONFIG := i386_defconfig
8 else
9 KBUILD_DEFCONFIG := x86_64_defconfig
10 endif
11else
12 KBUILD_DEFCONFIG := $(ARCH)_defconfig
13endif
14
15ifdef CONFIG_CC_IS_GCC
16RETPOLINE_CFLAGS := -mindirect-branch=thunk-extern -mindirect-branch-register
17RETPOLINE_VDSO_CFLAGS := -mindirect-branch=thunk-inline -mindirect-branch-register
18endif
19ifdef CONFIG_CC_IS_CLANG
20RETPOLINE_CFLAGS := -mretpoline-external-thunk
21RETPOLINE_VDSO_CFLAGS := -mretpoline
22endif
23RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch-cs-prefix)
24
25ifdef CONFIG_MITIGATION_RETHUNK
26RETHUNK_CFLAGS := -mfunction-return=thunk-extern
27RETHUNK_RUSTFLAGS := -Zfunction-return=thunk-extern
28RETPOLINE_CFLAGS += $(RETHUNK_CFLAGS)
29RETPOLINE_RUSTFLAGS += $(RETHUNK_RUSTFLAGS)
30endif
31
32export RETHUNK_CFLAGS
33export RETHUNK_RUSTFLAGS
34export RETPOLINE_CFLAGS
35export RETPOLINE_RUSTFLAGS
36export RETPOLINE_VDSO_CFLAGS
37
38# For gcc stack alignment is specified with -mpreferred-stack-boundary,
39# clang has the option -mstack-alignment for that purpose.
40ifdef CONFIG_CC_IS_GCC
41 cc_stack_align4 := -mpreferred-stack-boundary=2
42 cc_stack_align8 := -mpreferred-stack-boundary=3
43endif
44ifdef CONFIG_CC_IS_CLANG
45 cc_stack_align4 := -mstack-alignment=4
46 cc_stack_align8 := -mstack-alignment=8
47endif
48
49# How to compile the 16-bit code. Note we always compile for -march=i386;
50# that way we can complain to the user if the CPU is insufficient.
51REALMODE_CFLAGS := -std=gnu11 -fms-extensions -m16 -g -Os \
52 -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
53 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
54 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
55 -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
56
57REALMODE_CFLAGS += -ffreestanding
58REALMODE_CFLAGS += -fno-stack-protector
59REALMODE_CFLAGS += -Wno-address-of-packed-member
60REALMODE_CFLAGS += $(cc_stack_align4)
61REALMODE_CFLAGS += $(CLANG_FLAGS)
62ifdef CONFIG_CC_IS_CLANG
63REALMODE_CFLAGS += -Wno-gnu
64REALMODE_CFLAGS += -Wno-microsoft-anon-tag
65endif
66export REALMODE_CFLAGS
67
68# BITS is used as extension for files which are available in a 32 bit
69# and a 64 bit version to simplify shared Makefiles.
70# e.g.: obj-y += foo_$(BITS).o
71export BITS
72
73#
74# Prevent GCC from generating any FP code by mistake.
75#
76# This must happen before we try the -mpreferred-stack-boundary, see:
77#
78# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
79#
80KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -mno-sse4a
81KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json
82KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
83
84#
85# CFLAGS for compiling floating point code inside the kernel.
86#
87CC_FLAGS_FPU := -msse -msse2
88ifdef CONFIG_CC_IS_GCC
89CC_FLAGS_FPU += -mhard-float
90endif
91
92ifeq ($(CONFIG_X86_KERNEL_IBT),y)
93#
94# Kernel IBT has S_CET.NOTRACK_EN=0, as such the compilers must not generate
95# NOTRACK prefixes. Current generation compilers unconditionally employ NOTRACK
96# for jump-tables, as such, disable jump-tables for now.
97#
98# (jump-tables are implicitly disabled by RETPOLINE)
99#
100# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
101#
102KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
103KBUILD_RUSTFLAGS += -Zcf-protection=branch $(if $(call rustc-min-version,109300),-Cjump-tables=n,-Zno-jump-tables)
104else
105KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
106endif
107
108ifeq ($(CONFIG_X86_32),y)
109 BITS := 32
110 UTS_MACHINE := i386
111 CHECKFLAGS += -D__i386__
112
113 KBUILD_AFLAGS += -m32
114 KBUILD_CFLAGS += -m32
115
116 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
117
118 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
119 # with nonstandard options
120 KBUILD_CFLAGS += -fno-pic
121
122 # Align the stack to the register width instead of using the default
123 # alignment of 16 bytes. This reduces stack usage and the number of
124 # alignment instructions.
125 KBUILD_CFLAGS += $(cc_stack_align4)
126
127 # CPU-specific tuning. Anything which can be shared with UML should go here.
128 include $(srctree)/arch/x86/Makefile_32.cpu
129 KBUILD_CFLAGS += $(cflags-y)
130
131 ifneq ($(call clang-min-version, 160000),y)
132 # https://github.com/llvm/llvm-project/issues/53645
133 KBUILD_CFLAGS += -ffreestanding
134 endif
135
136 percpu_seg := fs
137else
138 BITS := 64
139 UTS_MACHINE := x86_64
140 CHECKFLAGS += -D__x86_64__
141
142 KBUILD_AFLAGS += -m64
143 KBUILD_CFLAGS += -m64
144
145 # Align jump targets to 1 byte, not the default 16 bytes:
146 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
147
148 # Pack loops tightly as well:
149 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
150
151 # Don't autogenerate traditional x87 instructions
152 KBUILD_CFLAGS += -mno-80387
153 KBUILD_CFLAGS += -mno-fp-ret-in-387
154
155 # By default gcc and clang use a stack alignment of 16 bytes for x86.
156 # However the standard kernel entry on x86-64 leaves the stack on an
157 # 8-byte boundary. If the compiler isn't informed about the actual
158 # alignment it will generate extra alignment instructions for the
159 # default alignment which keep the stack *mis*aligned.
160 # Furthermore an alignment to the register width reduces stack usage
161 # and the number of alignment instructions.
162 KBUILD_CFLAGS += $(cc_stack_align8)
163
164 # Use -mskip-rax-setup if supported.
165 KBUILD_CFLAGS += -mskip-rax-setup
166
167ifdef CONFIG_X86_NATIVE_CPU
168 KBUILD_CFLAGS += -march=native
169 KBUILD_RUSTFLAGS += -Ctarget-cpu=native
170else
171 KBUILD_CFLAGS += -march=x86-64 -mtune=generic
172 KBUILD_RUSTFLAGS += -Ctarget-cpu=x86-64 -Ztune-cpu=generic
173endif
174
175 KBUILD_CFLAGS += -mno-red-zone
176 KBUILD_CFLAGS += -mcmodel=kernel
177 KBUILD_RUSTFLAGS += -Cno-redzone=y
178 KBUILD_RUSTFLAGS += -Ccode-model=kernel
179
180 percpu_seg := gs
181endif
182
183ifeq ($(CONFIG_STACKPROTECTOR),y)
184 ifeq ($(CONFIG_SMP),y)
185 KBUILD_CFLAGS += -mstack-protector-guard-reg=$(percpu_seg)
186 KBUILD_CFLAGS += -mstack-protector-guard-symbol=__ref_stack_chk_guard
187 else
188 KBUILD_CFLAGS += -mstack-protector-guard=global
189 endif
190endif
191
192#
193# If the function graph tracer is used with mcount instead of fentry,
194# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
195# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
196#
197ifdef CONFIG_FUNCTION_GRAPH_TRACER
198 ifndef CONFIG_HAVE_FENTRY
199 ACCUMULATE_OUTGOING_ARGS := 1
200 endif
201endif
202
203ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
204 # This compiler flag is not supported by Clang:
205 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
206endif
207
208# Workaround for a gcc prelease that unfortunately was shipped in a suse release
209KBUILD_CFLAGS += -Wno-sign-compare
210#
211KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
212
213# Avoid indirect branches in kernel to deal with Spectre
214ifdef CONFIG_MITIGATION_RETPOLINE
215 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
216 KBUILD_RUSTFLAGS += $(RETPOLINE_RUSTFLAGS)
217 # Additionally, avoid generating expensive indirect jumps which
218 # are subject to retpolines for small number of switch cases.
219 # LLVM turns off jump table generation by default when under
220 # retpoline builds, however, gcc does not for x86. This has
221 # only been fixed starting from gcc stable version 8.4.0 and
222 # onwards, but not for older ones. See gcc bug #86952.
223 ifndef CONFIG_CC_IS_CLANG
224 KBUILD_CFLAGS += -fno-jump-tables
225 endif
226endif
227
228ifdef CONFIG_MITIGATION_SLS
229 KBUILD_CFLAGS += -mharden-sls=all
230endif
231
232ifdef CONFIG_CALL_PADDING
233PADDING_CFLAGS := -fpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
234KBUILD_CFLAGS += $(PADDING_CFLAGS)
235export PADDING_CFLAGS
236
237PADDING_RUSTFLAGS := -Zpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
238KBUILD_RUSTFLAGS += $(PADDING_RUSTFLAGS)
239export PADDING_RUSTFLAGS
240endif
241
242KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
243
244#
245# The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
246# the linker to force 2MB page size regardless of the default page size used
247# by the linker.
248#
249ifdef CONFIG_X86_64
250LDFLAGS_vmlinux += -z max-page-size=0x200000
251endif
252
253
254archscripts: scripts_basic
255 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
256
257###
258# Syscall table generation
259
260archheaders:
261 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
262
263###
264# <asm/cpufeaturemasks.h> header generation
265
266cpufeaturemasks.hdr := arch/x86/include/generated/asm/cpufeaturemasks.h
267cpufeaturemasks.awk := $(srctree)/arch/x86/tools/cpufeaturemasks.awk
268cpufeatures_hdr := $(srctree)/arch/x86/include/asm/cpufeatures.h
269targets += $(cpufeaturemasks.hdr)
270 filechk_gen_featuremasks = $(AWK) -f $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG)
271
272$(cpufeaturemasks.hdr): $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) FORCE
273 $(shell mkdir -p $(dir $@))
274 $(call filechk,gen_featuremasks)
275archprepare: $(cpufeaturemasks.hdr)
276
277###
278# Kernel objects
279
280libs-y += arch/x86/lib/
281
282# drivers-y are linked after core-y
283drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
284drivers-$(CONFIG_PCI) += arch/x86/pci/
285
286# suspend and hibernation support
287drivers-$(CONFIG_PM) += arch/x86/power/
288
289drivers-$(CONFIG_VIDEO) += arch/x86/video/
290
291####
292# boot loader support. Several targets are kept for legacy purposes
293
294boot := arch/x86/boot
295
296BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 hdimage isoimage
297
298PHONY += bzImage $(BOOT_TARGETS)
299
300# Default kernel to build
301all: bzImage
302
303# KBUILD_IMAGE specify target image being built
304KBUILD_IMAGE := $(boot)/bzImage
305
306bzImage: vmlinux
307ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
308 $(Q)$(MAKE) $(build)=arch/x86/tools posttest
309endif
310 $(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
311 $(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
312 $(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
313
314$(BOOT_TARGETS): vmlinux
315 $(Q)$(MAKE) $(build)=$(boot) $@
316
317PHONY += install
318install:
319 $(call cmd,install)
320
321vdso-install-$(CONFIG_X86_64) += arch/x86/entry/vdso/vdso64.so.dbg
322vdso-install-$(CONFIG_X86_X32_ABI) += arch/x86/entry/vdso/vdsox32.so.dbg
323vdso-install-$(CONFIG_COMPAT_32) += arch/x86/entry/vdso/vdso32.so.dbg
324
325archprepare: checkbin
326checkbin:
327ifdef CONFIG_MITIGATION_RETPOLINE
328ifeq ($(RETPOLINE_CFLAGS),)
329 @echo "You are building kernel with non-retpoline compiler." >&2
330 @echo "Please update your compiler." >&2
331 @false
332endif
333endif
334
335ifdef CONFIG_UNWINDER_ORC
336orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
337orc_hash_sh := $(srctree)/scripts/orc_hash.sh
338targets += $(orc_hash_h)
339quiet_cmd_orc_hash = GEN $@
340 cmd_orc_hash = mkdir -p $(dir $@); \
341 $(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
342$(orc_hash_h): $(srctree)/arch/x86/include/asm/orc_types.h $(orc_hash_sh) FORCE
343 $(call if_changed,orc_hash)
344archprepare: $(orc_hash_h)
345endif
346
347archclean:
348 $(Q)rm -rf $(objtree)/arch/i386
349 $(Q)rm -rf $(objtree)/arch/x86_64
350
351define archhelp
352 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
353 echo ' install - Install kernel using (your) ~/bin/$(INSTALLKERNEL) or'
354 echo ' (distribution) /sbin/$(INSTALLKERNEL) or install to '
355 echo ' $$(INSTALL_PATH) and run lilo'
356 echo ''
357 echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
358 echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
359 echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
360 echo ' hdimage - Create a BIOS/EFI hard disk image (arch/x86/boot/hdimage)'
361 echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
362 echo ' bzdisk/fdimage*/hdimage/isoimage also accept:'
363 echo ' FDARGS="..." arguments for the booted kernel'
364 echo ' FDINITRD=file initrd for the booted kernel'
365
366endef