build: factorise generation of the linker scripts

In Arm and X86 makefile, generating the linker script is the same, so
we can simply have both call the same macro.

We need to add *.lds files into extra-y so that Rules.mk can find the
.*.cmd dependency file and load it.

Change made to the command line:
- Use cpp_flags macro which simply filter -Wa,% options from $(a_flags).
- Added -D__LINKER__ even it is only used by Arm's lds.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/Rules.mk

@@ -238,6 +238,10 @@ cmd_cpp_s_S = $(CPP) $(call cpp_flags,$(a_flags)) -MQ $@ -o $@ $<
 %.s: %.S FORCE
 	$(call if_changed,cpp_s_S)
 
+# Linker scripts, .lds.S -> .lds
+quiet_cmd_cpp_lds_S = LDS     $@
+cmd_cpp_lds_S = $(CPP) -P $(call cpp_flags,$(a_flags)) -D__LINKER__ -MQ $@ -o $@ $<
+
 # Add intermediate targets:
 # When building objects with specific suffix patterns, add intermediate
 # targets that the final targets are derived from.

xen/arch/arm/Makefile

@@ -67,6 +67,8 @@ obj-y += vsmc.o
 obj-y += vpsci.o
 obj-y += vuart.o
 
+extra-y += xen.lds
+
 #obj-bin-y += ....o
 
 ifneq ($(CONFIG_DTB_FILE),"")
@@ -132,8 +134,8 @@ $(TARGET)-syms: prelink.o xen.lds
 .PHONY: include
 include:
 
-xen.lds: xen.lds.S
-	$(CPP) -P $(a_flags) -D__LINKER__ -MQ $@ -o $@ $<
+xen.lds: xen.lds.S FORCE
+	$(call if_changed,cpp_lds_S)
 
 dtb.o: $(patsubst "%",%,$(CONFIG_DTB_FILE))
 

xen/arch/x86/Makefile

@@ -78,6 +78,7 @@ obj-y += sysctl.o
 endif
 
 extra-y += asm-macros.i
+extra-y += xen.lds
 
 ifneq ($(CONFIG_HVM),y)
 x86_emulate.o: CFLAGS-y += -Wno-unused-label
@@ -238,6 +239,7 @@ endif
 note_file_option ?= $(note_file)
 
 ifeq ($(XEN_BUILD_PE),y)
+extra-y += efi.lds
 $(TARGET).efi: prelink.o $(note_file) efi.lds efi/relocs-dummy.o efi/mkreloc
 ifeq ($(CONFIG_DEBUG_INFO),y)
 	$(if $(filter --strip-debug,$(EFI_LDFLAGS)),echo,:) "Will strip debug info from $(@F)"
@@ -290,8 +292,8 @@ $(BASEDIR)/include/asm-x86/asm-macros.h: asm-macros.i Makefile
 	$(call move-if-changed,$@.new,$@)
 
 efi.lds: AFLAGS-y += -DEFI
-xen.lds efi.lds: xen.lds.S
-	$(CPP) -P $(call cpp_flags,$(a_flags)) -MQ $@ -o $@ $<
+xen.lds efi.lds: xen.lds.S FORCE
+	$(call if_changed,cpp_lds_S)
 
 boot/mkelf32: boot/mkelf32.c
 	$(HOSTCC) $(HOSTCFLAGS) -o $@ $<