x86, percpu: Fix DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED()

DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED() put percpu variables in
.page_aligned section without adding any alignment restrictions.
Currently, this doesn't cause any problem because all users of the
macros have explicit page alignment and page-sized but it's much safer
to enforce page alignment from the macros.  After all, it's what they
claim to do.

Add __aligned(PAGE_SIZE) to DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED() and
drop explicit alignment from it users.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f1961c0..12493c5 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1008,8 +1008,7 @@
 };
 
 static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
-	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ])
-	__aligned(PAGE_SIZE);
+	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
 
 /* May not be marked __init: used by software suspend */
 void syscall_init(void)