arc: kernel: Return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/kernel/signal.c

@@ -96,7 +96,7 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
 			     sizeof(sf->uc.uc_mcontext.regs.scratch));
 	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
 
-	return err;
+	return err ? -EFAULT : 0;
 }
 
 static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
@@ -110,7 +110,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
 				&(sf->uc.uc_mcontext.regs.scratch),
 				sizeof(sf->uc.uc_mcontext.regs.scratch));
 	if (err)
-		return err;
+		return -EFAULT;
 
 	set_current_blocked(&set);
 	regs->bta	= uregs.scratch.bta;