mips: prevent hitting do_notify_resume() with !user_mode(regs)

too late to do anything there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/mips/kernel/entry.S

@@ -167,6 +167,9 @@ work_notifysig:				# deal with pending signals and
 FEXPORT(syscall_exit_work_partial)
 	SAVE_STATIC
 syscall_exit_work:
+	LONG_L	t0, PT_STATUS(sp)		# returning to kernel mode?
+	andi	t0, t0, KU_USER
+	beqz	t0, resume_kernel
 	li	t0, _TIF_WORK_SYSCALL_EXIT
 	and	t0, a2			# a2 is preloaded with TI_FLAGS
 	beqz	t0, work_pending	# trace bit set?

arch/mips/kernel/signal.c

@@ -560,14 +560,6 @@ static void do_signal(struct pt_regs *regs)
 	siginfo_t info;
 	int signr;
 
-	/*
-	 * We want the common case to go fast, which is why we may in certain
-	 * cases get here from kernel mode. Just return without doing anything
-	 * if so.
-	 */
-	if (!user_mode(regs))
-		return;
-
 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 	if (signr > 0) {
 		/* Whee!  Actually deliver the signal.  */