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 <linux/security.h>
  32 #include <asm/pgalloc.h>
  33
  34 unsigned long mmap_rnd_mask;
  35 static unsigned long mmap_align_mask;
  36
  37 static unsigned long stack_maxrandom_size(void)
  38 {
  39         if (!(current->flags & PF_RANDOMIZE))
  40                 return 0;
  41         if (current->personality & ADDR_NO_RANDOMIZE)
  42                 return 0;
  43         return STACK_RND_MASK << PAGE_SHIFT;
  44 }
  45
  46 /*
  47  * Top of mmap area (just below the process stack).
  48  *
  49  * Leave at least a ~32 MB hole.
  50  */
  51 #define MIN_GAP (32*1024*1024)
  52 #define MAX_GAP (STACK_TOP/6*5)
  53
  54 static inline int mmap_is_legacy(void)
  55 {
  56         if (current->personality & ADDR_COMPAT_LAYOUT)
  57                 return 1;
  58         if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
  59                 return 1;
  60         return sysctl_legacy_va_layout;
  61 }
  62
  63 unsigned long arch_mmap_rnd(void)
  64 {
  65         if (is_32bit_task())
  66                 return (get_random_int() & 0x7ff) << PAGE_SHIFT;
  67         else
  68                 return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
  69 }
  70
  71 static unsigned long mmap_base_legacy(unsigned long rnd)
  72 {
  73         return TASK_UNMAPPED_BASE + rnd;
  74 }
  75
  76 static inline unsigned long mmap_base(unsigned long rnd)
  77 {
  78         unsigned long gap = rlimit(RLIMIT_STACK);
  79
  80         if (gap < MIN_GAP)
  81                 gap = MIN_GAP;
  82         else if (gap > MAX_GAP)
  83                 gap = MAX_GAP;
  84         gap &= PAGE_MASK;
  85         return STACK_TOP - stack_maxrandom_size() - rnd - gap;
  86 }
  87
  88 unsigned long
  89 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  90                 unsigned long len, unsigned long pgoff, unsigned long flags)
  91 {
  92         struct mm_struct *mm = current->mm;
  93         struct vm_area_struct *vma;
  94         struct vm_unmapped_area_info info;
  95         int do_color_align;
  96
  97         if (len > TASK_SIZE - mmap_min_addr)
  98                 return -ENOMEM;
  99
 100         if (flags & MAP_FIXED)
 101                 return addr;
 102
 103         if (addr) {
 104                 addr = PAGE_ALIGN(addr);
 105                 vma = find_vma(mm, addr);
 106                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 107                     (!vma || addr + len <= vma->vm_start))
 108                         return addr;
 109         }
 110
 111         do_color_align = 0;
 112         if (filp || (flags & MAP_SHARED))
 113                 do_color_align = !is_32bit_task();
 114
 115         info.flags = 0;
 116         info.length = len;
 117         info.low_limit = mm->mmap_base;
 118         info.high_limit = TASK_SIZE;
 119         info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
 120         info.align_offset = pgoff << PAGE_SHIFT;
 121         return vm_unmapped_area(&info);
 122 }
 123
 124 unsigned long
 125 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 126                           const unsigned long len, const unsigned long pgoff,
 127                           const unsigned long flags)
 128 {
 129         struct vm_area_struct *vma;
 130         struct mm_struct *mm = current->mm;
 131         unsigned long addr = addr0;
 132         struct vm_unmapped_area_info info;
 133         int do_color_align;
 134
 135         /* requested length too big for entire address space */
 136         if (len > TASK_SIZE - mmap_min_addr)
 137                 return -ENOMEM;
 138
 139         if (flags & MAP_FIXED)
 140                 return addr;
 141
 142         /* requesting a specific address */
 143         if (addr) {
 144                 addr = PAGE_ALIGN(addr);
 145                 vma = find_vma(mm, addr);
 146                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 147                                 (!vma || addr + len <= vma->vm_start))
 148                         return addr;
 149         }
 150
 151         do_color_align = 0;
 152         if (filp || (flags & MAP_SHARED))
 153                 do_color_align = !is_32bit_task();
 154
 155         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 156         info.length = len;
 157         info.low_limit = max(PAGE_SIZE, mmap_min_addr);
 158         info.high_limit = mm->mmap_base;
 159         info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
 160         info.align_offset = pgoff << PAGE_SHIFT;
 161         addr = vm_unmapped_area(&info);
 162
 163         /*
 164          * A failed mmap() very likely causes application failure,
 165          * so fall back to the bottom-up function here. This scenario
 166          * can happen with large stack limits and large mmap()
 167          * allocations.
 168          */
 169         if (addr & ~PAGE_MASK) {
 170                 VM_BUG_ON(addr != -ENOMEM);
 171                 info.flags = 0;
 172                 info.low_limit = TASK_UNMAPPED_BASE;
 173                 info.high_limit = TASK_SIZE;
 174                 addr = vm_unmapped_area(&info);
 175         }
 176
 177         return addr;
 178 }
 179
 180 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 181 {
 182         if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
 183                 return 0;
 184         if (!(flags & MAP_FIXED))
 185                 addr = 0;
 186         if ((addr + len) >= TASK_SIZE)
 187                 return crst_table_upgrade(current->mm, 1UL << 53);
 188         return 0;
 189 }
 190
 191 static unsigned long
 192 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 193                 unsigned long len, unsigned long pgoff, unsigned long flags)
 194 {
 195         struct mm_struct *mm = current->mm;
 196         unsigned long area;
 197         int rc;
 198
 199         area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 200         if (!(area & ~PAGE_MASK))
 201                 return area;
 202         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 203                 /* Upgrade the page table to 4 levels and retry. */
 204                 rc = crst_table_upgrade(mm, 1UL << 53);
 205                 if (rc)
 206                         return (unsigned long) rc;
 207                 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 208         }
 209         return area;
 210 }
 211
 212 static unsigned long
 213 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 214                           const unsigned long len, const unsigned long pgoff,
 215                           const unsigned long flags)
 216 {
 217         struct mm_struct *mm = current->mm;
 218         unsigned long area;
 219         int rc;
 220
 221         area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 222         if (!(area & ~PAGE_MASK))
 223                 return area;
 224         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 225                 /* Upgrade the page table to 4 levels and retry. */
 226                 rc = crst_table_upgrade(mm, 1UL << 53);
 227                 if (rc)
 228                         return (unsigned long) rc;
 229                 area = arch_get_unmapped_area_topdown(filp, addr, len,
 230                                                       pgoff, flags);
 231         }
 232         return area;
 233 }
 234 /*
 235  * This function, called very early during the creation of a new
 236  * process VM image, sets up which VM layout function to use:
 237  */
 238 void arch_pick_mmap_layout(struct mm_struct *mm)
 239 {
 240         unsigned long random_factor = 0UL;
 241
 242         if (current->flags & PF_RANDOMIZE)
 243                 random_factor = arch_mmap_rnd();
 244
 245         /*
 246          * Fall back to the standard layout if the personality
 247          * bit is set, or if the expected stack growth is unlimited:
 248          */
 249         if (mmap_is_legacy()) {
 250                 mm->mmap_base = mmap_base_legacy(random_factor);
 251                 mm->get_unmapped_area = s390_get_unmapped_area;
 252         } else {
 253                 mm->mmap_base = mmap_base(random_factor);
 254                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 255         }
 256 }
 257
 258 static int __init setup_mmap_rnd(void)
 259 {
 260         struct cpuid cpu_id;
 261
 262         get_cpu_id(&cpu_id);
 263         switch (cpu_id.machine) {
 264         case 0x9672:
 265         case 0x2064:
 266         case 0x2066:
 267         case 0x2084:
 268         case 0x2086:
 269         case 0x2094:
 270         case 0x2096:
 271         case 0x2097:
 272         case 0x2098:
 273         case 0x2817:
 274         case 0x2818:
 275         case 0x2827:
 276         case 0x2828:
 277                 mmap_rnd_mask = 0x7ffUL;
 278                 mmap_align_mask = 0UL;
 279                 break;
 280         case 0x2964:    /* z13 */
 281         default:
 282                 mmap_rnd_mask = 0x3ff80UL;
 283                 mmap_align_mask = 0x7fUL;
 284                 break;
 285         }
 286         return 0;
 287 }
 288 early_initcall(setup_mmap_rnd);