Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *  linux/arch/i386/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/random.h>

#include <linux/sched.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(struct mm_struct *mm)

{

        unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;

        unsigned long random_factor = 0;

        if (current->flags & PF_RANDOMIZE)

                random_factor = get_random_int() % (1024*1024);

        if (gap < MIN_GAP)

                gap = MIN_GAP;

        else if (gap > MAX_GAP)

                gap = MAX_GAP;

        return PAGE_ALIGN(TASK_SIZE - gap - random_factor);

}

/*

 * 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 (sysctl_legacy_va_layout ||

                        (current->personality & ADDR_COMPAT_LAYOUT) ||

                        current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) {

                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);

                mm->get_unmapped_area = arch_get_unmapped_area_topdown;

                mm->unmap_area = arch_unmap_area_topdown;

        }

}