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
  32 /*
  33  * Top of mmap area (just below the process stack).
  34  *
  35  * Leave an at least ~128 MB hole.
  36  */
  37 #define MIN_GAP (128*1024*1024)
  38 #define MAX_GAP (TASK_SIZE/6*5)
  39
  40 static inline unsigned long mmap_base(void)
  41 {
  42         unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
  43
  44         if (gap < MIN_GAP)
  45                 gap = MIN_GAP;
  46         else if (gap > MAX_GAP)
  47                 gap = MAX_GAP;
  48
  49         return TASK_SIZE - (gap & PAGE_MASK);
  50 }
  51
  52 static inline int mmap_is_legacy(void)
  53 {
  54 #ifdef CONFIG_64BIT
  55         /*
  56          * Force standard allocation for 64 bit programs.
  57          */
  58         if (!test_thread_flag(TIF_31BIT))
  59                 return 1;
  60 #endif
  61         return sysctl_legacy_va_layout ||
  62             (current->personality & ADDR_COMPAT_LAYOUT) ||
  63             current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;
  64 }
  65
  66 #ifndef CONFIG_64BIT
  67
  68 /*
  69  * This function, called very early during the creation of a new
  70  * process VM image, sets up which VM layout function to use:
  71  */
  72 void arch_pick_mmap_layout(struct mm_struct *mm)
  73 {
  74         /*
  75          * Fall back to the standard layout if the personality
  76          * bit is set, or if the expected stack growth is unlimited:
  77          */
  78         if (mmap_is_legacy()) {
  79                 mm->mmap_base = TASK_UNMAPPED_BASE;
  80                 mm->get_unmapped_area = arch_get_unmapped_area;
  81                 mm->unmap_area = arch_unmap_area;
  82         } else {
  83                 mm->mmap_base = mmap_base();
  84                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
  85                 mm->unmap_area = arch_unmap_area_topdown;
  86         }
  87 }
  88 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
  89
  90 #else
  91
  92 static unsigned long
  93 s390_get_unmapped_area(struct file *filp, unsigned long addr,
  94                 unsigned long len, unsigned long pgoff, unsigned long flags)
  95 {
  96         struct mm_struct *mm = current->mm;
  97         int rc;
  98
  99         addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 100         if (addr & ~PAGE_MASK)
 101                 return addr;
 102         if (unlikely(mm->context.asce_limit < addr + len)) {
 103                 rc = crst_table_upgrade(mm, addr + len);
 104                 if (rc)
 105                         return (unsigned long) rc;
 106         }
 107         return addr;
 108 }
 109
 110 static unsigned long
 111 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 112                           const unsigned long len, const unsigned long pgoff,
 113                           const unsigned long flags)
 114 {
 115         struct mm_struct *mm = current->mm;
 116         unsigned long addr = addr0;
 117         int rc;
 118
 119         addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 120         if (addr & ~PAGE_MASK)
 121                 return addr;
 122         if (unlikely(mm->context.asce_limit < addr + len)) {
 123                 rc = crst_table_upgrade(mm, addr + len);
 124                 if (rc)
 125                         return (unsigned long) rc;
 126         }
 127         return addr;
 128 }
 129 /*
 130  * This function, called very early during the creation of a new
 131  * process VM image, sets up which VM layout function to use:
 132  */
 133 void arch_pick_mmap_layout(struct mm_struct *mm)
 134 {
 135         /*
 136          * Fall back to the standard layout if the personality
 137          * bit is set, or if the expected stack growth is unlimited:
 138          */
 139         if (mmap_is_legacy()) {
 140                 mm->mmap_base = TASK_UNMAPPED_BASE;
 141                 mm->get_unmapped_area = s390_get_unmapped_area;
 142                 mm->unmap_area = arch_unmap_area;
 143         } else {
 144                 mm->mmap_base = mmap_base();
 145                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 146                 mm->unmap_area = arch_unmap_area_topdown;
 147         }
 148 }
 149 EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 150
 151 #endif