Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Ingo Molnar:
 "A handful of objtool fixes, most of them related to making the UAPI
  header-syncing warnings easier to read and easier to act upon"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/headers: Sync objtool UAPI header
  objtool: Fix cross-build
  objtool: Move kernel headers/code sync check to a script
  objtool: Move synced files to their original relative locations
  objtool: Make unreachable annotation inline asms explicitly volatile
  objtool: Add a comment for the unreachable annotation macros

include/linux/compiler.h

@@ -88,17 +88,22 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 
 /* Unreachable code */
 #ifdef CONFIG_STACK_VALIDATION
+/*
+ * These macros help objtool understand GCC code flow for unreachable code.
+ * The __COUNTER__ based labels are a hack to make each instance of the macros
+ * unique, to convince GCC not to merge duplicate inline asm statements.
+ */
 #define annotate_reachable() ({						\
-	asm("%c0:\n\t"							\
-	    ".pushsection .discard.reachable\n\t"			\
-	    ".long %c0b - .\n\t"					\
-	    ".popsection\n\t" : : "i" (__COUNTER__));			\
+	asm volatile("%c0:\n\t"						\
+		     ".pushsection .discard.reachable\n\t"		\
+		     ".long %c0b - .\n\t"				\
+		     ".popsection\n\t" : : "i" (__COUNTER__));		\
 })
 #define annotate_unreachable() ({					\
-	asm("%c0:\n\t"							\
-	    ".pushsection .discard.unreachable\n\t"			\
-	    ".long %c0b - .\n\t"					\
-	    ".popsection\n\t" : : "i" (__COUNTER__));			\
+	asm volatile("%c0:\n\t"						\
+		     ".pushsection .discard.unreachable\n\t"		\
+		     ".long %c0b - .\n\t"				\
+		     ".popsection\n\t" : : "i" (__COUNTER__));		\
 })
 #define ASM_UNREACHABLE							\
 	"999:\n\t"							\