nds32: add support for TIF_NOTIFY_SIGNAL

Wire up TIF_NOTIFY_SIGNAL handling for nds32.

Cc: Nick Hu <nickhu@andestech.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

arch/nds32/include/asm/thread_info.h

@@ -48,6 +48,7 @@ struct thread_info {
 #define TIF_NEED_RESCHED	2
 #define TIF_SINGLESTEP		3
 #define TIF_NOTIFY_RESUME	4	/* callback before returning to user */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_SYSCALL_TRACE	8
 #define TIF_POLLING_NRFLAG	17
 #define TIF_MEMDIE		18
@@ -57,6 +58,7 @@ struct thread_info {
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)

arch/nds32/kernel/ex-exit.S

@@ -120,7 +120,7 @@ work_pending:
 	andi	$p1, $r1, #_TIF_NEED_RESCHED
 	bnez	$p1, work_resched
 
-	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME
+	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME|#_TIF_NOTIFY_SIGNAL
 	beqz	$p1, no_work_pending
 
 	move	$r0, $sp			! 'regs'

arch/nds32/kernel/signal.c

@@ -376,7 +376,7 @@ static void do_signal(struct pt_regs *regs)
 asmlinkage void
 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags)
 {
-	if (thread_flags & _TIF_SIGPENDING)
+	if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_flags & _TIF_NOTIFY_RESUME)