xref: /linux/scripts/Makefile.lib (revision a16219bdd34777cce35b9b6a704bfbaad28adb72)
1# SPDX-License-Identifier: GPL-2.0
2# Backward compatibility
3asflags-y  += $(EXTRA_AFLAGS)
4ccflags-y  += $(EXTRA_CFLAGS)
5cppflags-y += $(EXTRA_CPPFLAGS)
6ldflags-y  += $(EXTRA_LDFLAGS)
7
8# flags that take effect in current and sub directories
9KBUILD_AFLAGS += $(subdir-asflags-y)
10KBUILD_CFLAGS += $(subdir-ccflags-y)
11KBUILD_RUSTFLAGS += $(subdir-rustflags-y)
12
13# Figure out what we need to build from the various variables
14# ===========================================================================
15
16# When an object is listed to be built compiled-in and modular,
17# only build the compiled-in version
18obj-m := $(filter-out $(obj-y),$(obj-m))
19
20# Libraries are always collected in one lib file.
21# Filter out objects already built-in
22lib-y := $(filter-out $(obj-y), $(sort $(lib-y) $(lib-m)))
23
24# Subdirectories we need to descend into
25subdir-ym := $(sort $(subdir-y) $(subdir-m) \
26			$(patsubst %/,%, $(filter %/, $(obj-y) $(obj-m))))
27
28# Handle objects in subdirs:
29# - If we encounter foo/ in $(obj-y), replace it by foo/built-in.a and
30#   foo/modules.order
31# - If we encounter foo/ in $(obj-m), replace it by foo/modules.order
32#
33# Generate modules.order to determine modorder. Unfortunately, we don't have
34# information about ordering between -y and -m subdirs. Just put -y's first.
35
36ifdef need-modorder
37obj-m := $(patsubst %/,%/modules.order, $(filter %/, $(obj-y)) $(obj-m))
38else
39obj-m := $(filter-out %/, $(obj-m))
40endif
41
42ifdef need-builtin
43obj-y		:= $(patsubst %/, %/built-in.a, $(obj-y))
44else
45obj-y		:= $(filter-out %/, $(obj-y))
46endif
47
48# Expand $(foo-objs) $(foo-y) etc. by replacing their individuals
49suffix-search = $(strip $(foreach s, $3, $($(1:%$(strip $2)=%$s))))
50# List composite targets that are constructed by combining other targets
51multi-search = $(sort $(foreach m, $1, $(if $(call suffix-search, $m, $2, $3 -), $m)))
52# List primitive targets that are compiled from source files
53real-search = $(foreach m, $1, $(if $(call suffix-search, $m, $2, $3 -), $(call suffix-search, $m, $2, $3), $m))
54
55# If $(foo-objs), $(foo-y), $(foo-m), or $(foo-) exists, foo.o is a composite object
56multi-obj-y := $(call multi-search, $(obj-y), .o, -objs -y)
57multi-obj-m := $(call multi-search, $(obj-m), .o, -objs -y -m)
58multi-obj-ym := $(multi-obj-y) $(multi-obj-m)
59
60# Replace multi-part objects by their individual parts,
61# including built-in.a from subdirectories
62real-obj-y := $(call real-search, $(obj-y), .o, -objs -y)
63real-obj-m := $(call real-search, $(obj-m), .o, -objs -y -m)
64
65always-y += $(always-m)
66
67# hostprogs-always-y += foo
68# ... is a shorthand for
69# hostprogs += foo
70# always-y  += foo
71hostprogs += $(hostprogs-always-y) $(hostprogs-always-m)
72always-y += $(hostprogs-always-y) $(hostprogs-always-m)
73
74# userprogs-always-y is likewise.
75userprogs += $(userprogs-always-y) $(userprogs-always-m)
76always-y += $(userprogs-always-y) $(userprogs-always-m)
77
78# Add subdir path
79
80ifneq ($(obj),.)
81extra-y		:= $(addprefix $(obj)/,$(extra-y))
82always-y	:= $(addprefix $(obj)/,$(always-y))
83targets		:= $(addprefix $(obj)/,$(targets))
84obj-m		:= $(addprefix $(obj)/,$(obj-m))
85lib-y		:= $(addprefix $(obj)/,$(lib-y))
86real-obj-y	:= $(addprefix $(obj)/,$(real-obj-y))
87real-obj-m	:= $(addprefix $(obj)/,$(real-obj-m))
88multi-obj-m	:= $(addprefix $(obj)/, $(multi-obj-m))
89subdir-ym	:= $(addprefix $(obj)/,$(subdir-ym))
90endif
91
92# Finds the multi-part object the current object will be linked into.
93# If the object belongs to two or more multi-part objects, list them all.
94modname-multi = $(sort $(foreach m,$(multi-obj-ym),\
95		$(if $(filter $*.o, $(call suffix-search, $m, .o, -objs -y -m)),$(m:.o=))))
96
97__modname = $(or $(modname-multi),$(basetarget))
98
99modname = $(subst $(space),:,$(__modname))
100modfile = $(addprefix $(obj)/,$(__modname))
101
102# target with $(obj)/ and its suffix stripped
103target-stem = $(basename $(patsubst $(obj)/%,%,$@))
104
105# These flags are needed for modversions and compiling, so we define them here
106# $(modname_flags) defines KBUILD_MODNAME as the name of the module it will
107# end up in (or would, if it gets compiled in)
108name-fix-token = $(subst $(comma),_,$(subst -,_,$1))
109name-fix = $(call stringify,$(call name-fix-token,$1))
110basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
111modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname)) \
112		 -D__KBUILD_MODNAME=kmod_$(call name-fix-token,$(modname))
113modfile_flags  = -DKBUILD_MODFILE=$(call stringify,$(modfile))
114
115_c_flags       = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), \
116                     $(filter-out $(ccflags-remove-y), \
117                         $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(ccflags-y)) \
118                     $(CFLAGS_$(target-stem).o))
119_rust_flags    = $(filter-out $(RUSTFLAGS_REMOVE_$(target-stem).o), \
120                     $(filter-out $(rustflags-remove-y), \
121                         $(KBUILD_RUSTFLAGS) $(rustflags-y)) \
122                     $(RUSTFLAGS_$(target-stem).o))
123_a_flags       = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), \
124                     $(filter-out $(asflags-remove-y), \
125                         $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(asflags-y)) \
126                     $(AFLAGS_$(target-stem).o))
127_cpp_flags     = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(target-stem).lds)
128
129#
130# Enable gcov profiling flags for a file, directory or for all files depending
131# on variables GCOV_PROFILE_obj.o, GCOV_PROFILE and CONFIG_GCOV_PROFILE_ALL
132# (in this order)
133#
134ifeq ($(CONFIG_GCOV_KERNEL),y)
135_c_flags += $(if $(patsubst n%,, \
136		$(GCOV_PROFILE_$(target-stem).o)$(GCOV_PROFILE)$(if $(is-kernel-object),$(CONFIG_GCOV_PROFILE_ALL))), \
137		$(CFLAGS_GCOV))
138endif
139
140#
141# Enable address sanitizer flags for kernel except some files or directories
142# we don't want to check (depends on variables KASAN_SANITIZE_obj.o, KASAN_SANITIZE)
143#
144ifeq ($(CONFIG_KASAN),y)
145ifneq ($(CONFIG_KASAN_HW_TAGS),y)
146_c_flags += $(if $(patsubst n%,, \
147		$(KASAN_SANITIZE_$(target-stem).o)$(KASAN_SANITIZE)$(is-kernel-object)), \
148		$(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE))
149endif
150endif
151
152ifeq ($(CONFIG_KMSAN),y)
153_c_flags += $(if $(patsubst n%,, \
154		$(KMSAN_SANITIZE_$(target-stem).o)$(KMSAN_SANITIZE)$(is-kernel-object)), \
155		$(CFLAGS_KMSAN))
156_c_flags += $(if $(patsubst n%,, \
157		$(KMSAN_ENABLE_CHECKS_$(target-stem).o)$(KMSAN_ENABLE_CHECKS)$(is-kernel-object)), \
158		, -mllvm -msan-disable-checks=1)
159endif
160
161ifeq ($(CONFIG_UBSAN),y)
162_c_flags += $(if $(patsubst n%,, \
163		$(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_SANITIZE)$(is-kernel-object)), \
164		$(CFLAGS_UBSAN))
165_c_flags += $(if $(patsubst n%,, \
166		$(UBSAN_SIGNED_WRAP_$(target-stem).o)$(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_SIGNED_WRAP)$(UBSAN_SANITIZE)$(is-kernel-object)), \
167		$(CFLAGS_UBSAN_SIGNED_WRAP))
168endif
169
170ifeq ($(CONFIG_KCOV),y)
171_c_flags += $(if $(patsubst n%,, \
172	$(KCOV_INSTRUMENT_$(target-stem).o)$(KCOV_INSTRUMENT)$(if $(is-kernel-object),$(CONFIG_KCOV_INSTRUMENT_ALL))), \
173	$(CFLAGS_KCOV))
174endif
175
176#
177# Enable KCSAN flags except some files or directories we don't want to check
178# (depends on variables KCSAN_SANITIZE_obj.o, KCSAN_SANITIZE)
179#
180ifeq ($(CONFIG_KCSAN),y)
181_c_flags += $(if $(patsubst n%,, \
182	$(KCSAN_SANITIZE_$(target-stem).o)$(KCSAN_SANITIZE)$(is-kernel-object)), \
183	$(CFLAGS_KCSAN))
184# Some uninstrumented files provide implied barriers required to avoid false
185# positives: set KCSAN_INSTRUMENT_BARRIERS for barrier instrumentation only.
186_c_flags += $(if $(patsubst n%,, \
187	$(KCSAN_INSTRUMENT_BARRIERS_$(target-stem).o)$(KCSAN_INSTRUMENT_BARRIERS)n), \
188	-D__KCSAN_INSTRUMENT_BARRIERS__)
189endif
190
191# $(src) for including checkin headers from generated source files
192# $(obj) for including generated headers from checkin source files
193ifeq ($(KBUILD_EXTMOD),)
194ifdef building_out_of_srctree
195_c_flags   += $(addprefix -I, $(src) $(obj))
196_a_flags   += $(addprefix -I, $(src) $(obj))
197_cpp_flags += $(addprefix -I, $(src) $(obj))
198endif
199endif
200
201# If $(is-kernel-object) is 'y', this object will be linked to vmlinux or modules
202is-kernel-object = $(or $(part-of-builtin),$(part-of-module))
203
204part-of-builtin = $(if $(filter $(basename $@).o, $(real-obj-y) $(lib-y)),y)
205part-of-module = $(if $(filter $(basename $@).o, $(real-obj-m)),y)
206quiet_modtag = $(if $(part-of-module),[M],   )
207
208modkern_cflags =                                          \
209	$(if $(part-of-module),                           \
210		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
211		$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL) $(modfile_flags))
212
213modkern_rustflags =                                              \
214	$(if $(part-of-module),                                   \
215		$(KBUILD_RUSTFLAGS_MODULE) $(RUSTFLAGS_MODULE), \
216		$(KBUILD_RUSTFLAGS_KERNEL) $(RUSTFLAGS_KERNEL))
217
218modkern_aflags = $(if $(part-of-module),				\
219			$(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE),	\
220			$(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL) $(modfile_flags))
221
222c_flags        = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
223		 -include $(srctree)/include/linux/compiler_types.h       \
224		 $(_c_flags) $(modkern_cflags)                           \
225		 $(basename_flags) $(modname_flags)
226
227rust_flags     = $(_rust_flags) $(modkern_rustflags) @$(objtree)/include/generated/rustc_cfg
228
229a_flags        = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
230		 $(_a_flags) $(modkern_aflags) $(modname_flags)
231
232cpp_flags      = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
233		 $(_cpp_flags)
234
235ld_flags       = $(KBUILD_LDFLAGS) $(ldflags-y) $(LDFLAGS_$(@F))
236
237ifdef CONFIG_OBJTOOL
238
239objtool := $(objtree)/tools/objtool/objtool
240
241objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK)		+= --hacks=jump_label
242objtool-args-$(CONFIG_HAVE_NOINSTR_HACK)		+= --hacks=noinstr
243objtool-args-$(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)	+= --hacks=skylake
244objtool-args-$(CONFIG_X86_KERNEL_IBT)			+= --ibt
245objtool-args-$(CONFIG_FINEIBT)				+= --cfi
246objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL)	+= --mcount
247ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
248objtool-args-$(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT)		+= --mnop
249endif
250objtool-args-$(CONFIG_UNWINDER_ORC)			+= --orc
251objtool-args-$(CONFIG_MITIGATION_RETPOLINE)		+= --retpoline
252objtool-args-$(CONFIG_MITIGATION_RETHUNK)		+= --rethunk
253objtool-args-$(CONFIG_MITIGATION_SLS)			+= --sls
254objtool-args-$(CONFIG_STACK_VALIDATION)			+= --stackval
255objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE)		+= --static-call
256objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION)		+= --uaccess
257objtool-args-$(CONFIG_GCOV_KERNEL)			+= --no-unreachable
258objtool-args-$(CONFIG_PREFIX_SYMBOLS)			+= --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
259
260objtool-args = $(objtool-args-y)					\
261	$(if $(delay-objtool), --link)					\
262	$(if $(part-of-module), --module)
263
264delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
265
266cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
267cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
268
269endif # CONFIG_OBJTOOL
270
271# Useful for describing the dependency of composite objects
272# Usage:
273#   $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)
274define multi_depend
275$(foreach m, $1, \
276	$(eval $m: \
277	$(addprefix $(obj)/, $(call suffix-search, $(patsubst $(obj)/%,%,$m), $2, $3))))
278endef
279
280# Copy a file
281# ===========================================================================
282# 'cp' preserves permissions. If you use it to copy a file in read-only srctree,
283# the copy would be read-only as well, leading to an error when executing the
284# rule next time. Use 'cat' instead in order to generate a writable file.
285quiet_cmd_copy = COPY    $@
286      cmd_copy = cat $< > $@
287
288$(obj)/%: $(src)/%_shipped
289	$(call cmd,copy)
290
291# Commands useful for building a boot image
292# ===========================================================================
293#
294#	Use as following:
295#
296#	target: source(s) FORCE
297#		$(if_changed,ld/objcopy/gzip)
298#
299#	and add target to 'targets' so that we know we have to
300#	read in the saved command line
301
302# Linking
303# ---------------------------------------------------------------------------
304
305quiet_cmd_ld = LD      $@
306      cmd_ld = $(LD) $(ld_flags) $(real-prereqs) -o $@
307
308# Archive
309# ---------------------------------------------------------------------------
310
311quiet_cmd_ar = AR      $@
312      cmd_ar = rm -f $@; $(AR) cDPrsT $@ $(real-prereqs)
313
314# Objcopy
315# ---------------------------------------------------------------------------
316
317quiet_cmd_objcopy = OBJCOPY $@
318cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
319
320# Gzip
321# ---------------------------------------------------------------------------
322
323quiet_cmd_gzip = GZIP    $@
324      cmd_gzip = cat $(real-prereqs) | $(KGZIP) -n -f -9 > $@
325
326# Bzip2
327# ---------------------------------------------------------------------------
328
329# Bzip2 and LZMA do not include size in file... so we have to fake that;
330# append the size as a 32-bit littleendian number as gzip does.
331size_append = printf $(shell						\
332dec_size=0;								\
333for F in $(real-prereqs); do					\
334	fsize=$$($(CONFIG_SHELL) $(srctree)/scripts/file-size.sh $$F);	\
335	dec_size=$$(expr $$dec_size + $$fsize);				\
336done;									\
337printf "%08x\n" $$dec_size |						\
338	sed 's/\(..\)/\1 /g' | {					\
339		read ch0 ch1 ch2 ch3;					\
340		for ch in $$ch3 $$ch2 $$ch1 $$ch0; do			\
341			printf '%s%03o' '\\' $$((0x$$ch)); 		\
342		done;							\
343	}								\
344)
345
346quiet_cmd_file_size = GEN     $@
347      cmd_file_size = $(size_append) > $@
348
349quiet_cmd_bzip2 = BZIP2   $@
350      cmd_bzip2 = cat $(real-prereqs) | $(KBZIP2) -9 > $@
351
352quiet_cmd_bzip2_with_size = BZIP2   $@
353      cmd_bzip2_with_size = { cat $(real-prereqs) | $(KBZIP2) -9; $(size_append); } > $@
354
355# Lzma
356# ---------------------------------------------------------------------------
357
358quiet_cmd_lzma = LZMA    $@
359      cmd_lzma = cat $(real-prereqs) | $(LZMA) -9 > $@
360
361quiet_cmd_lzma_with_size = LZMA    $@
362      cmd_lzma_with_size = { cat $(real-prereqs) | $(LZMA) -9; $(size_append); } > $@
363
364quiet_cmd_lzo = LZO     $@
365      cmd_lzo = cat $(real-prereqs) | $(KLZOP) -9 > $@
366
367quiet_cmd_lzo_with_size = LZO     $@
368      cmd_lzo_with_size = { cat $(real-prereqs) | $(KLZOP) -9; $(size_append); } > $@
369
370quiet_cmd_lz4 = LZ4     $@
371      cmd_lz4 = cat $(real-prereqs) | $(LZ4) -l -c1 stdin stdout > $@
372
373quiet_cmd_lz4_with_size = LZ4     $@
374      cmd_lz4_with_size = { cat $(real-prereqs) | $(LZ4) -l -c1 stdin stdout; \
375                  $(size_append); } > $@
376
377# U-Boot mkimage
378# ---------------------------------------------------------------------------
379
380MKIMAGE := $(srctree)/scripts/mkuboot.sh
381
382# SRCARCH just happens to match slightly more than ARCH (on sparc), so reduces
383# the number of overrides in arch makefiles
384UIMAGE_ARCH ?= $(SRCARCH)
385UIMAGE_COMPRESSION ?= $(or $(2),none)
386UIMAGE_OPTS-y ?=
387UIMAGE_TYPE ?= kernel
388UIMAGE_LOADADDR ?= arch_must_set_this
389UIMAGE_ENTRYADDR ?= $(UIMAGE_LOADADDR)
390UIMAGE_NAME ?= Linux-$(KERNELRELEASE)
391
392quiet_cmd_uimage = UIMAGE  $@
393      cmd_uimage = $(BASH) $(MKIMAGE) -A $(UIMAGE_ARCH) -O linux \
394			-C $(UIMAGE_COMPRESSION) $(UIMAGE_OPTS-y) \
395			-T $(UIMAGE_TYPE) \
396			-a $(UIMAGE_LOADADDR) -e $(UIMAGE_ENTRYADDR) \
397			-n '$(UIMAGE_NAME)' -d $< $@
398
399# Flat Image Tree (FIT)
400# This allows for packaging of a kernel and all devicetrees files, using
401# compression.
402# ---------------------------------------------------------------------------
403
404MAKE_FIT := $(srctree)/scripts/make_fit.py
405
406# Use this to override the compression algorithm
407FIT_COMPRESSION ?= gzip
408
409quiet_cmd_fit = FIT     $@
410      cmd_fit = $(MAKE_FIT) -o $@ --arch $(UIMAGE_ARCH) --os linux \
411		--name '$(UIMAGE_NAME)' \
412		$(if $(findstring 1,$(KBUILD_VERBOSE)),-v) \
413		$(if $(FIT_DECOMPOSE_DTBS),--decompose-dtbs) \
414		--compress $(FIT_COMPRESSION) -k $< @$(word 2,$^)
415
416# XZ
417# ---------------------------------------------------------------------------
418# Use xzkern to compress the kernel image and xzmisc to compress other things.
419#
420# xzkern uses a big LZMA2 dictionary since it doesn't increase memory usage
421# of the kernel decompressor. A BCJ filter is used if it is available for
422# the target architecture. xzkern also appends uncompressed size of the data
423# using size_append. The .xz format has the size information available at
424# the end of the file too, but it's in more complex format and it's good to
425# avoid changing the part of the boot code that reads the uncompressed size.
426# Note that the bytes added by size_append will make the xz tool think that
427# the file is corrupt. This is expected.
428#
429# xzmisc doesn't use size_append, so it can be used to create normal .xz
430# files. xzmisc uses smaller LZMA2 dictionary than xzkern, because a very
431# big dictionary would increase the memory usage too much in the multi-call
432# decompression mode. A BCJ filter isn't used either.
433quiet_cmd_xzkern = XZKERN  $@
434      cmd_xzkern = cat $(real-prereqs) | sh $(srctree)/scripts/xz_wrap.sh > $@
435
436quiet_cmd_xzkern_with_size = XZKERN  $@
437      cmd_xzkern_with_size = { cat $(real-prereqs) | sh $(srctree)/scripts/xz_wrap.sh; \
438                     $(size_append); } > $@
439
440quiet_cmd_xzmisc = XZMISC  $@
441      cmd_xzmisc = cat $(real-prereqs) | $(XZ) --check=crc32 --lzma2=dict=1MiB > $@
442
443# ZSTD
444# ---------------------------------------------------------------------------
445# Appends the uncompressed size of the data using size_append. The .zst
446# format has the size information available at the beginning of the file too,
447# but it's in a more complex format and it's good to avoid changing the part
448# of the boot code that reads the uncompressed size.
449#
450# Note that the bytes added by size_append will make the zstd tool think that
451# the file is corrupt. This is expected.
452#
453# zstd uses a maximum window size of 8 MB. zstd22 uses a maximum window size of
454# 128 MB. zstd22 is used for kernel compression because it is decompressed in a
455# single pass, so zstd doesn't need to allocate a window buffer. When streaming
456# decompression is used, like initramfs decompression, zstd22 should likely not
457# be used because it would require zstd to allocate a 128 MB buffer.
458
459quiet_cmd_zstd = ZSTD    $@
460      cmd_zstd = cat $(real-prereqs) | $(ZSTD) -19 > $@
461
462quiet_cmd_zstd22 = ZSTD22  $@
463      cmd_zstd22 = cat $(real-prereqs) | $(ZSTD) -22 --ultra > $@
464
465quiet_cmd_zstd22_with_size = ZSTD22  $@
466      cmd_zstd22_with_size = { cat $(real-prereqs) | $(ZSTD) -22 --ultra; $(size_append); } > $@
467
468# ASM offsets
469# ---------------------------------------------------------------------------
470
471# Default sed regexp - multiline due to syntax constraints
472#
473# Use [:space:] because LLVM's integrated assembler inserts <tab> around
474# the .ascii directive whereas GCC keeps the <space> as-is.
475define sed-offsets
476	's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; \
477	/^->/{s:->#\(.*\):/* \1 */:; \
478	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
479	s:->::; p;}'
480endef
481
482# Use filechk to avoid rebuilds when a header changes, but the resulting file
483# does not
484define filechk_offsets
485	 echo "#ifndef $2"; \
486	 echo "#define $2"; \
487	 echo "/*"; \
488	 echo " * DO NOT MODIFY."; \
489	 echo " *"; \
490	 echo " * This file was generated by Kbuild"; \
491	 echo " */"; \
492	 echo ""; \
493	 sed -ne $(sed-offsets) < $<; \
494	 echo ""; \
495	 echo "#endif"
496endef
497