alpha: switch to generic sigaltstack

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 336393c..02d02c0 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -122,12 +122,6 @@
 	return sigsuspend(&blocked);
 }
 
-asmlinkage int
-sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
-{
-	return do_sigaltstack(uss, uoss, rdusp());
-}
-
 /*
  * Do a signal return; undo the signal stack.
  */
@@ -418,9 +412,7 @@
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(0, &frame->uc.uc_link);
 	err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
-	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-	err |= __put_user(sas_ss_flags(oldsp), &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __save_altstack(&frame->uc.uc_stack, oldsp);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 
 				set->sig[0], oldsp);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));