[PATCH v2 2/7] Arm: split xen-syms linking rule

[Jan Beulich <jbeulich@suse.com>]

Doing so, besides (hopefully) adding clarity (not the least by way of
[re-]using pattern rules where possible), also avoids explicit recursive
$(MAKE) invocations.

By re-using the generic rules introduced when the respective x86 rule was
split,
- the .map file now isn't created after the final binary anymore,
- --strip-debug is passed to $(LD) during early linking passes (for
  consistency the option is also explicitly added to the optional linking
  pass rule),
- CONFIG_{SUPPRESS_DUPLICATE_SYMBOL_WARNINGS,ENFORCE_UNIQUE_SYMBOLS} are
  now properly respected.
Orphan section checking, otoh, is getting suppressed for now, until the
about a dozen warnings which would result have been taken care of.

While the 4th linking step continues to be avoided when possible, a
redundant invocation of $(NM) and tools/symbols (plus the assembling of
the resulting .S file) is hopefully deemed acceptable.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
As for the x86 patch, I'd like to keep the "beautification" part, i.e.
transforming to more use of Kbuild.include machinery, separate.

--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -84,40 +84,12 @@ ifeq ($(CONFIG_ARM_64),y)
 	ln -sf $(@F) $@.efi
 endif
 
-$(TARGET)-syms: $(objtree)/prelink.o $(obj)/xen.lds
-	$(objtree)/tools/symbols $(all_symbols) --empty > $(dot-target).0.S
-	$(MAKE) $(build)=$(@D) $(dot-target).0.o
-	$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
-	      $(dot-target).0.o -o $(dot-target).0
-	$(NM) -pa --format=sysv $(dot-target).0 \
-		| $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
-		> $(dot-target).1.S
-	$(MAKE) $(build)=$(@D) $(dot-target).1.o
-	$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
-	    $(dot-target).1.o -o $(dot-target).1
-	$(NM) -pa --format=sysv $(dot-target).1 \
-		| $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
-		> $(dot-target).2.S
-	$(MAKE) $(build)=$(@D) $(dot-target).2.o
-	if ! { $(call compare-symbol-tables, $(dot-target).1.o, $(dot-target).2.o) >/dev/null; }; \
-	then \
-		set -e; \
-		$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
-		    $(dot-target).2.o -o $(dot-target).2; \
-		$(NM) -pa --format=sysv $(dot-target).2 \
-			| $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
-			> $(dot-target).3.S; \
-		$(MAKE) $(build)=$(@D) $(dot-target).3.o; \
-		$(call compare-symbol-tables, $(dot-target).2.o, $(dot-target).3.o); \
-	else \
-		ln -sf $(dot-target).2.o $(dot-target).3.o; \
-	fi
-	$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
-	    $(dot-target).3.o -o $@
-	$(NM) -pa --format=sysv $@ \
-		| $(objtree)/tools/symbols --all-symbols --xensyms --sysv --sort \
-		> $@.map
-	rm -f $(dot-target).[0-9]* $(@D)/..$(@F).[0-9]*
+LAST_LINKING_PASS := 3
+
+include scripts/Makefile.link
+
+# Suppress orphan section checking for the time being.
+orphan-handling-y :=
 
 .PHONY: include
 include:
--- a/xen/scripts/Makefile.link
+++ b/xen/scripts/Makefile.link
@@ -33,6 +33,19 @@ final-image-check-y ?= true
 	$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $(filter %.o,$^) \
 	      $(build_id_linker) --strip-debug -o $@
 
+ifneq ($(LAST_LINKING_PASS),2)
+
+.$(TARGET)-syms.2: $(objtree)/prelink.o .$(TARGET)-syms.2.o $(obj)/xen.lds
+	if ! { $(call compare-symbol-tables, .$(TARGET)-syms.1.o, .$(TARGET)-syms.2.o) >/dev/null; }; \
+	then \
+		$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $(filter %.o,$^) \
+		      $(build_id_linker) --strip-debug -o $@; \
+	else \
+		ln -sf .$(TARGET)-syms.1 $@; \
+	fi
+
+endif
+
 .$(TARGET)-syms.$(LAST_LINKING_PASS): $(objtree)/prelink.o \
                                       .$(TARGET)-syms.$(LAST_LINKING_PASS).o \
                                       $(obj)/xen.lds