powerpc/pseries: Limit machine check stack to 4GB

 */

void __init emergency_stack_init(void)

{

	u64 limit;

	u64 limit, mce_limit;

	unsigned int i;

	/*

	 * initialized in kernel/irq.c. These are initialized here in order

	 * to have emergency stacks available as early as possible.

	 */

	limit = min(ppc64_bolted_size(), ppc64_rma_size);

	limit = mce_limit = min(ppc64_bolted_size(), ppc64_rma_size);

	/*

	 * Machine check on pseries calls rtas, but can't use the static

	 * rtas_args due to a machine check hitting while the lock is held.

	 * rtas args have to be under 4GB, so the machine check stack is

	 * limited to 4GB so args can be put on stack.

	 */

	if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > SZ_4G)

		mce_limit = SZ_4G;

	for_each_possible_cpu(i) {

		paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;

		paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;

		/* emergency stack for machine check exception handling. */

		paca_ptrs[i]->mc_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;

		paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE;

#endif

	}

}