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/mman.h>
  30 #include <linux/module.h>
  31 #include <linux/random.h>
  32 #include <linux/compat.h>
  33 #include <asm/pgalloc.h>
  34
  35 static unsigned long stack_maxrandom_size(void)
  36 {
  37         if (!(current->flags & PF_RANDOMIZE))
  38                 return 0;
  39         if (current->personality & ADDR_NO_RANDOMIZE)
  40                 return 0;
  41         return STACK_RND_MASK << PAGE_SHIFT;
  42 }
  43
  44 /*
  45  * Top of mmap area (just below the process stack).
  46  *
  47  * Leave at least a ~32 MB hole.
  48  */
  49 #define MIN_GAP (32*1024*1024)
  50 #define MAX_GAP (STACK_TOP/6*5)
  51
  52 static inline int mmap_is_legacy(void)
  53 {
  54         if (current->personality & ADDR_COMPAT_LAYOUT)
  55                 return 1;
  56         if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
  57                 return 1;
  58         return sysctl_legacy_va_layout;
  59 }
  60
  61 static unsigned long mmap_rnd(void)
  62 {
  63         if (!(current->flags & PF_RANDOMIZE))
  64                 return 0;
  65         /* 8MB randomization for mmap_base */
  66         return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
  67 }
  68
  69 static inline unsigned long mmap_base(void)
  70 {
  71         unsigned long gap = rlimit(RLIMIT_STACK);
  72
  73         if (gap < MIN_GAP)
  74                 gap = MIN_GAP;
  75         else if (gap > MAX_GAP)
  76                 gap = MAX_GAP;
  77         gap &= PAGE_MASK;
  78         return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
  79 }
  80
  81 #ifndef CONFIG_64BIT
  82
  83 /*
  84  * This function, called very early during the creation of a new
  85  * process VM image, sets up which VM layout function to use:
  86  */
  87 void arch_pick_mmap_layout(struct mm_struct *mm)
  88 {
  89         /*
  90          * Fall back to the standard layout if the personality
  91          * bit is set, or if the expected stack growth is unlimited:
  92          */
  93         if (mmap_is_legacy()) {
  94                 mm->mmap_base = TASK_UNMAPPED_BASE;
  95                 mm->get_unmapped_area = arch_get_unmapped_area;
  96                 mm->unmap_area = arch_unmap_area;
  97         } else {
  98                 mm->mmap_base = mmap_base();
  99                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 100                 mm->unmap_area = arch_unmap_area_topdown;
 101         }
 102 }
 103 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 104
 105 #else
 106
 107 int s390_mmap_check(unsigned long addr, unsigned long len)
 108 {
 109         if (!is_compat_task() &&
 110             len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
 111                 return crst_table_upgrade(current->mm, 1UL << 53);
 112         return 0;
 113 }
 114
 115 static unsigned long
 116 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 117                 unsigned long len, unsigned long pgoff, unsigned long flags)
 118 {
 119         struct mm_struct *mm = current->mm;
 120         unsigned long area;
 121         int rc;
 122
 123         area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 124         if (!(area & ~PAGE_MASK))
 125                 return area;
 126         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 127                 /* Upgrade the page table to 4 levels and retry. */
 128                 rc = crst_table_upgrade(mm, 1UL << 53);
 129                 if (rc)
 130                         return (unsigned long) rc;
 131                 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 132         }
 133         return area;
 134 }
 135
 136 static unsigned long
 137 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 138                           const unsigned long len, const unsigned long pgoff,
 139                           const unsigned long flags)
 140 {
 141         struct mm_struct *mm = current->mm;
 142         unsigned long area;
 143         int rc;
 144
 145         area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 146         if (!(area & ~PAGE_MASK))
 147                 return area;
 148         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 149                 /* Upgrade the page table to 4 levels and retry. */
 150                 rc = crst_table_upgrade(mm, 1UL << 53);
 151                 if (rc)
 152                         return (unsigned long) rc;
 153                 area = arch_get_unmapped_area_topdown(filp, addr, len,
 154                                                       pgoff, flags);
 155         }
 156         return area;
 157 }
 158 /*
 159  * This function, called very early during the creation of a new
 160  * process VM image, sets up which VM layout function to use:
 161  */
 162 void arch_pick_mmap_layout(struct mm_struct *mm)
 163 {
 164         /*
 165          * Fall back to the standard layout if the personality
 166          * bit is set, or if the expected stack growth is unlimited:
 167          */
 168         if (mmap_is_legacy()) {
 169                 mm->mmap_base = TASK_UNMAPPED_BASE;
 170                 mm->get_unmapped_area = s390_get_unmapped_area;
 171                 mm->unmap_area = arch_unmap_area;
 172         } else {
 173                 mm->mmap_base = mmap_base();
 174                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 175                 mm->unmap_area = arch_unmap_area_topdown;
 176         }
 177 }
 178 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 179
 180 #endif