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 unsigned long mmap_base_legacy(void)
  68 {
  69         return TASK_UNMAPPED_BASE + mmap_rnd();
  70 }
  71
  72 static inline unsigned long mmap_base(void)
  73 {
  74         unsigned long gap = rlimit(RLIMIT_STACK);
  75
  76         if (gap < MIN_GAP)
  77                 gap = MIN_GAP;
  78         else if (gap > MAX_GAP)
  79                 gap = MAX_GAP;
  80         gap &= PAGE_MASK;
  81         return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
  82 }
  83
  84 #ifndef CONFIG_64BIT
  85
  86 /*
  87  * This function, called very early during the creation of a new
  88  * process VM image, sets up which VM layout function to use:
  89  */
  90 void arch_pick_mmap_layout(struct mm_struct *mm)
  91 {
  92         /*
  93          * Fall back to the standard layout if the personality
  94          * bit is set, or if the expected stack growth is unlimited:
  95          */
  96         if (mmap_is_legacy()) {
  97                 mm->mmap_base = mmap_base_legacy();
  98                 mm->get_unmapped_area = arch_get_unmapped_area;
  99         } else {
 100                 mm->mmap_base = mmap_base();
 101                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 102         }
 103 }
 104
 105 #else
 106
 107 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 108 {
 109         if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
 110                 return 0;
 111         if (!(flags & MAP_FIXED))
 112                 addr = 0;
 113         if ((addr + len) >= TASK_SIZE)
 114                 return crst_table_upgrade(current->mm, 1UL << 53);
 115         return 0;
 116 }
 117
 118 static unsigned long
 119 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 120                 unsigned long len, unsigned long pgoff, unsigned long flags)
 121 {
 122         struct mm_struct *mm = current->mm;
 123         unsigned long area;
 124         int rc;
 125
 126         area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 127         if (!(area & ~PAGE_MASK))
 128                 return area;
 129         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 130                 /* Upgrade the page table to 4 levels and retry. */
 131                 rc = crst_table_upgrade(mm, 1UL << 53);
 132                 if (rc)
 133                         return (unsigned long) rc;
 134                 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 135         }
 136         return area;
 137 }
 138
 139 static unsigned long
 140 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 141                           const unsigned long len, const unsigned long pgoff,
 142                           const unsigned long flags)
 143 {
 144         struct mm_struct *mm = current->mm;
 145         unsigned long area;
 146         int rc;
 147
 148         area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 149         if (!(area & ~PAGE_MASK))
 150                 return area;
 151         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 152                 /* Upgrade the page table to 4 levels and retry. */
 153                 rc = crst_table_upgrade(mm, 1UL << 53);
 154                 if (rc)
 155                         return (unsigned long) rc;
 156                 area = arch_get_unmapped_area_topdown(filp, addr, len,
 157                                                       pgoff, flags);
 158         }
 159         return area;
 160 }
 161 /*
 162  * This function, called very early during the creation of a new
 163  * process VM image, sets up which VM layout function to use:
 164  */
 165 void arch_pick_mmap_layout(struct mm_struct *mm)
 166 {
 167         /*
 168          * Fall back to the standard layout if the personality
 169          * bit is set, or if the expected stack growth is unlimited:
 170          */
 171         if (mmap_is_legacy()) {
 172                 mm->mmap_base = mmap_base_legacy();
 173                 mm->get_unmapped_area = s390_get_unmapped_area;
 174         } else {
 175                 mm->mmap_base = mmap_base();
 176                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 177         }
 178 }
 179
 180 #endif