clean up duplicated alloc/free_thread_info

We duplicate alloc/free_thread_info defines on many platforms (the
majority uses __get_free_pages/free_pages).  This patch defines common
defines and removes these duplicated defines.
__HAVE_ARCH_THREAD_INFO_ALLOCATOR is introduced for platforms that do
something different.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-powerpc/thread_info.h b/include/asm-powerpc/thread_info.h
index b705c2a..a9db562 100644
--- a/include/asm-powerpc/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -66,20 +66,12 @@
 
 #if THREAD_SHIFT >= PAGE_SHIFT
 
-#define THREAD_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
-
-#ifdef CONFIG_DEBUG_STACK_USAGE
-#define alloc_thread_info(tsk)	\
-	((struct thread_info *)__get_free_pages(GFP_KERNEL | \
-		__GFP_ZERO, THREAD_ORDER))
-#else
-#define alloc_thread_info(tsk)	\
-	((struct thread_info *)__get_free_pages(GFP_KERNEL, THREAD_ORDER))
-#endif
-#define free_thread_info(ti)	free_pages((unsigned long)ti, THREAD_ORDER)
+#define THREAD_SIZE_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
 
 #else /* THREAD_SHIFT < PAGE_SHIFT */
 
+#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
+
 extern struct thread_info *alloc_thread_info(struct task_struct *tsk);
 extern void free_thread_info(struct thread_info *ti);