[IA64] signal(ia64): add a signal stack overflow check

	new_sp = scr->pt.r12;

	tramp_addr = (unsigned long) __kernel_sigtramp;

	if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(new_sp) == 0) {

	if (ka->sa.sa_flags & SA_ONSTACK) {

		int onstack = sas_ss_flags(new_sp);

		if (onstack == 0) {

			new_sp = current->sas_ss_sp + current->sas_ss_size;

			/*

		 * We need to check for the register stack being on the signal stack

		 * separately, because it's switched separately (memory stack is switched

		 * in the kernel, register stack is switched in the signal trampoline).

			 * We need to check for the register stack being on the

			 * signal stack separately, because it's switched

			 * separately (memory stack is switched in the kernel,

			 * register stack is switched in the signal trampoline).

			 */

			if (!rbs_on_sig_stack(scr->pt.ar_bspstore))

			new_rbs = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);

				new_rbs = ALIGN(current->sas_ss_sp,

						sizeof(long));

		} else if (onstack == SS_ONSTACK) {

			unsigned long check_sp;

			/*

			 * If we are on the alternate signal stack and would

			 * overflow it, don't. Return an always-bogus address

			 * instead so we will die with SIGSEGV.

			 */

			check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;

			if (!likely(on_sig_stack(check_sp)))

				return force_sigsegv_info(sig, (void __user *)

							  check_sp);

		}

	}

	frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);