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;