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mmap.c

/*
 *  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>
#include <asm/pgalloc.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;
}

#ifndef CONFIG_64BIT

/*
 * 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);

#else

static unsigned long
s390_get_unmapped_area(struct file *filp, unsigned long addr,
            unsigned long len, unsigned long pgoff, unsigned long flags)
{
      struct mm_struct *mm = current->mm;
      int rc;

      addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
      if (addr & ~PAGE_MASK)
            return addr;
      if (unlikely(mm->context.asce_limit < addr + len)) {
            rc = crst_table_upgrade(mm, addr + len);
            if (rc)
                  return (unsigned long) rc;
      }
      return addr;
}

static unsigned long
s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                    const unsigned long len, const unsigned long pgoff,
                    const unsigned long flags)
{
      struct mm_struct *mm = current->mm;
      unsigned long addr = addr0;
      int rc;

      addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
      if (addr & ~PAGE_MASK)
            return addr;
      if (unlikely(mm->context.asce_limit < addr + len)) {
            rc = crst_table_upgrade(mm, addr + len);
            if (rc)
                  return (unsigned long) rc;
      }
      return addr;
}
/*
 * 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 = s390_get_unmapped_area;
            mm->unmap_area = arch_unmap_area;
      } else {
            mm->mmap_base = mmap_base();
            mm->get_unmapped_area = s390_get_unmapped_area_topdown;
            mm->unmap_area = arch_unmap_area_topdown;
      }
}
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);

#endif

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