powerpc/mm: use helper fault_signal_pending()

Let powerpc code to use the new helper, by moving the signal handling
earlier before the retry logic.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Brian Geffon <bgeffon@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220160222.9422-1-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/mm/fault.c

@@ -582,6 +582,9 @@ good_area:
 
 	major |= fault & VM_FAULT_MAJOR;
 
+	if (fault_signal_pending(fault, regs))
+		return user_mode(regs) ? 0 : SIGBUS;
+
 	/*
 	 * Handle the retry right now, the mmap_sem has been released in that
 	 * case.
@@ -595,15 +598,8 @@ good_area:
 			 */
 			flags &= ~FAULT_FLAG_ALLOW_RETRY;
 			flags |= FAULT_FLAG_TRIED;
-			if (!fatal_signal_pending(current))
-				goto retry;
+			goto retry;
 		}
-
-		/*
-		 * User mode? Just return to handle the fatal exception otherwise
-		 * return to bad_page_fault
-		 */
-		return is_user ? 0 : SIGBUS;
 	}
 
 	up_read(&current->mm->mmap_sem);