[PATCH] page align emergency stack

The PPC64 ABI requires the stack to be 128 byte aligned (and that can
become important if AltiVec registers are saved there).  In the kernel,
that's usually dealt with by the fact that the stack has a page
more-or-less to itself.  However, the emergency stacks (used in SMP bringup
and when we detect a bad stack pointer) aren't necessarily page aligned, or
anything aligned for that matter.  This patch applies the necessary
alignement constraint to them.
Signed-off-by: David Gibson <dwg@au.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/pacaData.c

@@ -29,8 +29,10 @@ extern unsigned long __toc_start;
 
 /* Stack space used when we detect a bad kernel stack pointer, and
  * early in SMP boots before relocation is enabled.
+ *
+ * ABI requires stack to be 128-byte aligned
  */
-char emergency_stack[PAGE_SIZE * NR_CPUS];
+char emergency_stack[PAGE_SIZE * NR_CPUS] __attribute__((aligned(128)));
 
 /* The Paca is an array with one entry per processor.  Each contains an 
  * ItLpPaca, which contains the information shared between the