LXR linux/arch/s390/mm/mmap.c

   1/*
   2 *  linux/arch/s390/mm/mmap.c
   3 *
   4 *  flexible mmap layout support
   5 *
   6 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
   7 * All Rights Reserved.
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation; either version 2 of the License, or
  12 * (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 * GNU General Public License for more details.
  18 *
  19 * You should have received a copy of the GNU General Public License
  20 * along with this program; if not, write to the Free Software
  21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22 *
  23 *
  24 * Started by Ingo Molnar <mingo@elte.hu>
  25 */
  26
  27#include <linux/personality.h>
  28#include <linux/mm.h>
  29#include <linux/module.h>
  30#include <asm/pgalloc.h>
  31#include <asm/compat.h>
  32
  33/*
  34 * Top of mmap area (just below the process stack).
  35 *
  36 * Leave an at least ~128 MB hole.
  37 */
  38#define MIN_GAP (128*1024*1024)
  39#define MAX_GAP (STACK_TOP/6*5)
  40
  41static inline unsigned long mmap_base(void)
  42{
  43        unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
  44
  45        if (gap < MIN_GAP)
  46                gap = MIN_GAP;
  47        else if (gap > MAX_GAP)
  48                gap = MAX_GAP;
  49
  50        return STACK_TOP - (gap & PAGE_MASK);
  51}
  52
  53static inline int mmap_is_legacy(void)
  54{
  55#ifdef CONFIG_64BIT
  56        /*
  57         * Force standard allocation for 64 bit programs.
  58         */
  59        if (!is_compat_task())
  60                return 1;
  61#endif
  62        return sysctl_legacy_va_layout ||
  63            (current->personality & ADDR_COMPAT_LAYOUT) ||
  64            current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;
  65}
  66
  67#ifndef CONFIG_64BIT
  68
  69/*
  70 * This function, called very early during the creation of a new
  71 * process VM image, sets up which VM layout function to use:
  72 */
  73void arch_pick_mmap_layout(struct mm_struct *mm)
  74{
  75        /*
  76         * Fall back to the standard layout if the personality
  77         * bit is set, or if the expected stack growth is unlimited:
  78         */
  79        if (mmap_is_legacy()) {
  80                mm->mmap_base = TASK_UNMAPPED_BASE;
  81                mm->get_unmapped_area = arch_get_unmapped_area;
  82                mm->unmap_area = arch_unmap_area;
  83        } else {
  84                mm->mmap_base = mmap_base();
  85                mm->get_unmapped_area = arch_get_unmapped_area_topdown;
  86                mm->unmap_area = arch_unmap_area_topdown;
  87        }
  88}
  89EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
  90
  91#else
  92
  93int s390_mmap_check(unsigned long addr, unsigned long len)
  94{
  95        if (!is_compat_task() &&
  96            len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
  97                return crst_table_upgrade(current->mm, 1UL << 53);
  98        return 0;
  99}
 100
 101static unsigned long
 102s390_get_unmapped_area(struct file *filp, unsigned long addr,
 103                unsigned long len, unsigned long pgoff, unsigned long flags)
 104{
 105        struct mm_struct *mm = current->mm;
 106        unsigned long area;
 107        int rc;
 108
 109        area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 110        if (!(area & ~PAGE_MASK))
 111                return area;
 112        if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 113                /* Upgrade the page table to 4 levels and retry. */
 114                rc = crst_table_upgrade(mm, 1UL << 53);
 115                if (rc)
 116                        return (unsigned long) rc;
 117                area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 118        }
 119        return area;
 120}
 121
 122static unsigned long
 123s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 124                          const unsigned long len, const unsigned long pgoff,
 125                          const unsigned long flags)
 126{
 127        struct mm_struct *mm = current->mm;
 128        unsigned long area;
 129        int rc;
 130
 131        area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 132        if (!(area & ~PAGE_MASK))
 133                return area;
 134        if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 135                /* Upgrade the page table to 4 levels and retry. */
 136                rc = crst_table_upgrade(mm, 1UL << 53);
 137                if (rc)
 138                        return (unsigned long) rc;
 139                area = arch_get_unmapped_area_topdown(filp, addr, len,
 140                                                      pgoff, flags);
 141        }
 142        return area;
 143}
 144/*
 145 * This function, called very early during the creation of a new
 146 * process VM image, sets up which VM layout function to use:
 147 */
 148void arch_pick_mmap_layout(struct mm_struct *mm)
 149{
 150        /*
 151         * Fall back to the standard layout if the personality
 152         * bit is set, or if the expected stack growth is unlimited:
 153         */
 154        if (mmap_is_legacy()) {
 155                mm->mmap_base = TASK_UNMAPPED_BASE;
 156                mm->get_unmapped_area = s390_get_unmapped_area;
 157                mm->unmap_area = arch_unmap_area;
 158        } else {
 159                mm->mmap_base = mmap_base();
 160                mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 161                mm->unmap_area = arch_unmap_area_topdown;
 162        }
 163}
 164EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 165
 166#endif
 167