x86/asm: Make objtool unreachable macros independent from GCC version

The ASM_UNREACHABLE macro isn't GCC version-specific, so move it outside
the GCC 4.5+ check. Otherwise the 0-day robot will report objtool
warnings for uses of ASM_UNREACHABLE with GCC 4.4.

Also move the annotate_unreachable() macro so the related macros can
stay together.

Reported-by: kbuild test robot <[e-mail]>
Signed-off-by: Josh Poimboeuf <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Fixes: aa5d1b81500e ("x86/asm: Add ASM_UNREACHABLE")
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

include/linux/compiler-gcc.h

···
 #define __always_unused		__attribute__((unused))
 #define __mode(x)               __attribute__((mode(x)))
 
+#ifdef CONFIG_STACK_VALIDATION
+#define annotate_unreachable() ({					\
+	asm("%c0:\n\t"							\
+	    ".pushsection .discard.unreachable\n\t"			\
+	    ".long %c0b - .\n\t"					\
+	    ".popsection\n\t" : : "i" (__LINE__));			\
+})
+#define ASM_UNREACHABLE							\
+	"999:\n\t"							\
+	".pushsection .discard.unreachable\n\t"				\
+	".long 999b - .\n\t"						\
+	".popsection\n\t"
+#else
+#define annotate_unreachable()
+#endif
+
 /* gcc version specific checks */
 
 #if GCC_VERSION < 30200
···
 #ifdef LATENT_ENTROPY_PLUGIN
 #define __latent_entropy __attribute__((latent_entropy))
 #endif
-#endif
-
-#ifdef CONFIG_STACK_VALIDATION
-#define annotate_unreachable() ({					\
-	asm("%c0:\n\t"							\
-	    ".pushsection .discard.unreachable\n\t"			\
-	    ".long %c0b - .\n\t"					\
-	    ".popsection\n\t" : : "i" (__LINE__));			\
-})
-#define ASM_UNREACHABLE							\
-	"999:\n\t"							\
-	".pushsection .discard.unreachable\n\t"				\
-	".long 999b - .\n\t"						\
-	".popsection\n\t"
-#else
-#define annotate_unreachable()
 #endif
 
 /*