Force out-of-line instances of inline functions into .init.text in init-only code

Some compiler versions may choose to not inline certain functions, but
the check introduced in c/s 23003:768269c43914 wants .text to be
empty.

Also make sure an eventual error gets properly propagated even on the
first section of an object (.text typically being the first one), and
cover a broader set of sections.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

xen/Rules.mk

@@ -100,6 +100,8 @@ obj-y    := $(patsubst %/,%/built-in.o,$(obj-y))
 
 subdir-all := $(subdir-y) $(subdir-n)
 
+$(filter %.init.o,$(obj-y) $(obj-bin-y)): CFLAGS += -DINIT_SECTIONS_ONLY
+
 ifeq ($(lto),y)
 # Would like to handle all object files as bitcode, but objects made from
 # pure asm are in a different format and have to be collected separately.
@@ -158,8 +160,10 @@ SPECIAL_DATA_SECTIONS := rodata $(foreach n,1 2 4 8,rodata.str1.$(n)) \
 %.init.o: %.o Makefile
 	$(OBJDUMP) -h $< | sed -n '/[0-9]/{s,00*,0,g;p}' | while read idx name sz rest; do \
 		case "$$name" in \
-		.text|.data|.bss) test $$sz = 0 || \
-			{ echo "Error: size of $<:$$name is 0x$$sz" >&2; exit $$idx; };; \
+		.text|.text.*|.data|.data.*|.bss) \
+			test $$sz != 0 || continue; \
+			echo "Error: size of $<:$$name is 0x$$sz" >&2; \
+			exit $(shell expr $$idx + 1);; \
 		esac; \
 	done
 	$(OBJCOPY) $(foreach s,$(SPECIAL_DATA_SECTIONS),--rename-section .$(s)=.init.$(s)) $< $@

xen/include/xen/compiler.h

@@ -14,6 +14,15 @@
 #define always_inline __inline__ __attribute__ ((always_inline))
 #define noinline      __attribute__((noinline))
 
+#ifdef INIT_SECTIONS_ONLY
+/*
+ * For sources indicated to have only init code, make sure even
+ * inline functions not expanded inline get placed in .init.text.
+ */
+#include <xen/init.h>
+#define __inline__ __inline__ __init
+#endif
+
 #define __attribute_pure__  __attribute__((pure))
 #define __attribute_const__ __attribute__((__const__))