build: centralize / unify asm-offsets generation

Except for an additional prereq Arm and x86 have the same needs here,
and Arm can also benefit from the recent x86 side improvement. Recurse
into arch/*/ only for a phony include target (doing nothing on Arm),
and handle asm-offsets itself entirely locally to xen/Makefile.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>

.gitignore

@@ -318,13 +318,13 @@ xen/arch/x86/efi.lds
 xen/arch/x86/efi/check.efi
 xen/arch/x86/efi/mkreloc
 xen/arch/*/xen.lds
-xen/arch/*/asm-offsets.s
 xen/arch/*/efi/boot.c
 xen/arch/*/efi/compat.c
 xen/arch/*/efi/ebmalloc.c
 xen/arch/*/efi/efi.h
 xen/arch/*/efi/pe.c
 xen/arch/*/efi/runtime.c
+xen/asm-offsets.s
 xen/common/config_data.S
 xen/common/config.gz
 xen/include/headers*.chk

xen/Makefile

@@ -341,7 +341,7 @@ _clean: delete-unfresh-files
 	find . \( -name "*.o" -o -name ".*.d" -o -name ".*.d2" \
 		-o -name "*.gcno" -o -name ".*.cmd" \) -exec rm -f {} \;
 	rm -f include/asm $(TARGET) $(TARGET).gz $(TARGET).efi $(TARGET).efi.map $(TARGET)-syms $(TARGET)-syms.map *~ core
-	rm -f include/asm-*/asm-offsets.h
+	rm -f asm-offsets.s include/asm-*/asm-offsets.h
 	rm -f .banner
 
 .PHONY: _distclean
@@ -362,7 +362,7 @@ $(TARGET): delete-unfresh-files
 		done; \
 		true
 	$(MAKE) -f $(BASEDIR)/Rules.mk -C include
-	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) asm-offsets.s
+	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) include
 	$(MAKE) -f $(BASEDIR)/Rules.mk include/asm-$(TARGET_ARCH)/asm-offsets.h
 	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) $@
 
@@ -399,7 +399,11 @@ include/xen/compile.h: include/xen/compile.h.in .banner
 	@sed -rf tools/process-banner.sed < .banner >> $@.new
 	@mv -f $@.new $@
 
-include/asm-$(TARGET_ARCH)/asm-offsets.h: arch/$(TARGET_ARCH)/asm-offsets.s
+asm-offsets.s: arch/$(TARGET_ARCH)/$(TARGET_SUBARCH)/asm-offsets.c
+	$(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -g0 -o $@.new -MQ $@ $<
+	$(call move-if-changed,$@.new,$@)
+
+include/asm-$(TARGET_ARCH)/asm-offsets.h: asm-offsets.s
 	@(set -e; \
 	  echo "/*"; \
 	  echo " * DO NOT MODIFY."; \

xen/arch/arm/Makefile

@@ -130,8 +130,8 @@ $(TARGET)-syms: prelink.o xen.lds
 		>$(@D)/$(@F).map
 	rm -f $(@D)/.$(@F).[0-9]*
 
-asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c
-	$(CC) $(filter-out -flto,$(c_flags)) -S -o $@ $<
+.PHONY: include
+include:
 
 xen.lds: xen.lds.S
 	$(CPP) -P $(a_flags) -D__LINKER__ -MQ $@ -o $@ $<
@@ -140,6 +140,6 @@ dtb.o: $(patsubst "%",%,$(CONFIG_DTB_FILE))
 
 .PHONY: clean
 clean::
-	rm -f asm-offsets.s xen.lds
+	rm -f xen.lds
 	rm -f $(BASEDIR)/.xen-syms.[0-9]*
 	rm -f $(TARGET).efi

xen/arch/x86/Makefile

@@ -272,9 +272,8 @@ endif
 efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
 efi/buildid.o efi/relocs-dummy.o: ;
 
-asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c $(BASEDIR)/include/asm-x86/asm-macros.h
-	$(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -g0 -o $@.new -MQ $@ $<
-	$(call move-if-changed,$@.new,$@)
+.PHONY: include
+include: $(BASEDIR)/include/asm-x86/asm-macros.h
 
 asm-macros.i: CFLAGS-y += -D__ASSEMBLY__ -P
 
@@ -304,7 +303,7 @@ efi/mkreloc: efi/mkreloc.c
 
 .PHONY: clean
 clean::
-	rm -f asm-offsets.s *.lds *.new boot/*.o boot/*~ boot/core boot/mkelf32
+	rm -f *.lds *.new boot/*.o boot/*~ boot/core boot/mkelf32
 	rm -f asm-macros.i $(BASEDIR)/include/asm-x86/asm-macros.*
 	rm -f $(BASEDIR)/.xen-syms.[0-9]* boot/.*.d $(BASEDIR)/.xen.elf32
 	rm -f $(BASEDIR)/.xen.efi.[0-9]* efi/*.efi efi/mkreloc