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