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