kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE


Kaiser only needs to map one page of the stack; and
kernel/fork.c did not build on powerpc (no __PAGE_KERNEL).
It's all cleaner if linux/kaiser.h provides kaiser_map_thread_stack()
and kaiser_unmap_thread_stack() wrappers around asm/kaiser.h's
kaiser_add_mapping() and kaiser_remove_mapping().  And use
linux/kaiser.h in init/main.c to avoid the #ifdefs there.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/init/main.c b/init/main.c
index 2c009f7..99f0265 100644
--- a/init/main.c
+++ b/init/main.c
@@ -80,15 +80,13 @@
 #include <linux/integrity.h>
 #include <linux/proc_ns.h>
 #include <linux/io.h>
+#include <linux/kaiser.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
 #include <asm/setup.h>
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
-#ifdef CONFIG_KAISER
-#include <asm/kaiser.h>
-#endif
 
 static int kernel_init(void *);
 
@@ -476,9 +474,7 @@ static void __init mm_init(void)
 	pgtable_init();
 	vmalloc_init();
 	ioremap_huge_init();
-#ifdef CONFIG_KAISER
 	kaiser_init();
-#endif
 }
 
 asmlinkage __visible void __init start_kernel(void)