release/src-rt-6.x.4708/linux/linux-2.6.36/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
  41 static inline unsigned long mmap_base(void)
  42 {
  43         unsigned long gap = rlimit(RLIMIT_STACK);
  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
  53 static 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             rlimit(RLIMIT_STACK) == 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  */
  73 void 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 }
  89 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
  90
  91 #else
  92
  93 int 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
 101 static unsigned long
 102 s390_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
 122 static unsigned long
 123 s390_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  */
 148 void 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 }
 164 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 165
 166 #endif