arch/s390/mm/mmap.c

   1 /*
   2  *  flexible mmap layout support
   3  *
   4  * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
   5  * All Rights Reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  *
  22  * Started by Ingo Molnar <mingo@elte.hu>
  23  */
  24
  25 #include <linux/personality.h>
  26 #include <linux/mm.h>
  27 #include <linux/mman.h>
  28 #include <linux/module.h>
  29 #include <linux/random.h>
  30 #include <linux/compat.h>
  31 #include <asm/pgalloc.h>
  32
  33 static unsigned long stack_maxrandom_size(void)
  34 {
  35         if (!(current->flags & PF_RANDOMIZE))
  36                 return 0;
  37         if (current->personality & ADDR_NO_RANDOMIZE)
  38                 return 0;
  39         return STACK_RND_MASK << PAGE_SHIFT;
  40 }
  41
  42 /*
  43  * Top of mmap area (just below the process stack).
  44  *
  45  * Leave at least a ~32 MB hole.
  46  */
  47 #define MIN_GAP (32*1024*1024)
  48 #define MAX_GAP (STACK_TOP/6*5)
  49
  50 static inline int mmap_is_legacy(void)
  51 {
  52         if (current->personality & ADDR_COMPAT_LAYOUT)
  53                 return 1;
  54         if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
  55                 return 1;
  56         return sysctl_legacy_va_layout;
  57 }
  58
  59 static unsigned long mmap_rnd(void)
  60 {
  61         if (!(current->flags & PF_RANDOMIZE))
  62                 return 0;
  63         /* 8MB randomization for mmap_base */
  64         return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
  65 }
  66
  67 static inline unsigned long mmap_base(void)
  68 {
  69         unsigned long gap = rlimit(RLIMIT_STACK);
  70
  71         if (gap < MIN_GAP)
  72                 gap = MIN_GAP;
  73         else if (gap > MAX_GAP)
  74                 gap = MAX_GAP;
  75         gap &= PAGE_MASK;
  76         return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
  77 }
  78
  79 #ifndef CONFIG_64BIT
  80
  81 /*
  82  * This function, called very early during the creation of a new
  83  * process VM image, sets up which VM layout function to use:
  84  */
  85 void arch_pick_mmap_layout(struct mm_struct *mm)
  86 {
  87         /*
  88          * Fall back to the standard layout if the personality
  89          * bit is set, or if the expected stack growth is unlimited:
  90          */
  91         if (mmap_is_legacy()) {
  92                 mm->mmap_base = TASK_UNMAPPED_BASE;
  93                 mm->get_unmapped_area = arch_get_unmapped_area;
  94                 mm->unmap_area = arch_unmap_area;
  95         } else {
  96                 mm->mmap_base = mmap_base();
  97                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
  98                 mm->unmap_area = arch_unmap_area_topdown;
  99         }
 100 }
 101
 102 #else
 103
 104 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 105 {
 106         int rc;
 107
 108         if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
 109                 return 0;
 110         if (!(flags & MAP_FIXED))
 111                 addr = 0;
 112         if ((addr + len) >= TASK_SIZE) {
 113                 rc = crst_table_upgrade(current->mm, 1UL << 53);
 114                 if (rc)
 115                         return rc;
 116                 update_mm(current->mm, current);
 117         }
 118         return 0;
 119 }
 120
 121 static unsigned long
 122 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 123                 unsigned long len, unsigned long pgoff, unsigned long flags)
 124 {
 125         struct mm_struct *mm = current->mm;
 126         unsigned long area;
 127         int rc;
 128
 129         area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 130         if (!(area & ~PAGE_MASK))
 131                 return area;
 132         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 133                 /* Upgrade the page table to 4 levels and retry. */
 134                 rc = crst_table_upgrade(mm, 1UL << 53);
 135                 if (rc)
 136                         return (unsigned long) rc;
 137                 update_mm(mm, current);
 138                 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 139         }
 140         return area;
 141 }
 142
 143 static unsigned long
 144 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 145                           const unsigned long len, const unsigned long pgoff,
 146                           const unsigned long flags)
 147 {
 148         struct mm_struct *mm = current->mm;
 149         unsigned long area;
 150         int rc;
 151
 152         area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 153         if (!(area & ~PAGE_MASK))
 154                 return area;
 155         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 156                 /* Upgrade the page table to 4 levels and retry. */
 157                 rc = crst_table_upgrade(mm, 1UL << 53);
 158                 if (rc)
 159                         return (unsigned long) rc;
 160                 update_mm(mm, current);
 161                 area = arch_get_unmapped_area_topdown(filp, addr, len,
 162                                                       pgoff, flags);
 163         }
 164         return area;
 165 }
 166 /*
 167  * This function, called very early during the creation of a new
 168  * process VM image, sets up which VM layout function to use:
 169  */
 170 void arch_pick_mmap_layout(struct mm_struct *mm)
 171 {
 172         /*
 173          * Fall back to the standard layout if the personality
 174          * bit is set, or if the expected stack growth is unlimited:
 175          */
 176         if (mmap_is_legacy()) {
 177                 mm->mmap_base = TASK_UNMAPPED_BASE;
 178                 mm->get_unmapped_area = s390_get_unmapped_area;
 179                 mm->unmap_area = arch_unmap_area;
 180         } else {
 181                 mm->mmap_base = mmap_base();
 182                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 183                 mm->unmap_area = arch_unmap_area_topdown;
 184         }
 185 }
 186
 187 #endif