/* *  linux/arch/s390/mm/mmap.c * *  flexible mmap layout support * * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. * All Rights Reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA * * * Started by Ingo Molnar <mingo@elte.hu> */#include <linux/personality.h>#include <linux/mm.h>#include <linux/module.h>/* * Top of mmap area (just below the process stack). * * Leave an at least ~128 MB hole. */#define MIN_GAP (128*1024*1024)#define MAX_GAP (TASK_SIZE/6*5)static inline unsigned long mmap_base(void){	unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;	if (gap < MIN_GAP)		gap = MIN_GAP;	else if (gap > MAX_GAP)		gap = MAX_GAP;	return TASK_SIZE - (gap & PAGE_MASK);}static inline int mmap_is_legacy(void){#ifdef CONFIG_64BIT	/*	 * Force standard allocation for 64 bit programs.	 */	if (!test_thread_flag(TIF_31BIT))		return 1;#endif	return sysctl_legacy_va_layout ||	    (current->personality & ADDR_COMPAT_LAYOUT) ||	    current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;}/* * This function, called very early during the creation of a new * process VM image, sets up which VM layout function to use: */void arch_pick_mmap_layout(struct mm_struct *mm){	/*	 * Fall back to the standard layout if the personality	 * bit is set, or if the expected stack growth is unlimited:	 */	if (mmap_is_legacy()) {		mm->mmap_base = TASK_UNMAPPED_BASE;		mm->get_unmapped_area = arch_get_unmapped_area;		mm->unmap_area = arch_unmap_area;	} else {		mm->mmap_base = mmap_base();		mm->get_unmapped_area = arch_get_unmapped_area_topdown;		mm->unmap_area = arch_unmap_area_topdown;	}}EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);