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 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 static unsigned long mmap_rnd(void)
  64 {
  65         if (!(current->flags & PF_RANDOMIZE))
  66                 return 0;
  67         if (is_32bit_task())
  68                 return (get_random_int() & 0x7ff) << PAGE_SHIFT;
  69         else
  70                 return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
  71 }
  72
  73 static unsigned long mmap_base_legacy(void)
  74 {
  75         return TASK_UNMAPPED_BASE + mmap_rnd();
  76 }
  77
  78 static inline unsigned long mmap_base(void)
  79 {
  80         unsigned long gap = rlimit(RLIMIT_STACK);
  81
  82         if (gap < MIN_GAP)
  83                 gap = MIN_GAP;
  84         else if (gap > MAX_GAP)
  85                 gap = MAX_GAP;
  86         gap &= PAGE_MASK;
  87         return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
  88 }
  89
  90 unsigned long
  91 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  92                 unsigned long len, unsigned long pgoff, unsigned long flags)
  93 {
  94         struct mm_struct *mm = current->mm;
  95         struct vm_area_struct *vma;
  96         struct vm_unmapped_area_info info;
  97         int do_color_align;
  98
  99         if (len > TASK_SIZE - mmap_min_addr)
 100                 return -ENOMEM;
 101
 102         if (flags & MAP_FIXED)
 103                 return addr;
 104
 105         if (addr) {
 106                 addr = PAGE_ALIGN(addr);
 107                 vma = find_vma(mm, addr);
 108                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 109                     (!vma || addr + len <= vma->vm_start))
 110                         return addr;
 111         }
 112
 113         do_color_align = 0;
 114         if (filp || (flags & MAP_SHARED))
 115                 do_color_align = !is_32bit_task();
 116
 117         info.flags = 0;
 118         info.length = len;
 119         info.low_limit = mm->mmap_base;
 120         info.high_limit = TASK_SIZE;
 121         info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
 122         info.align_offset = pgoff << PAGE_SHIFT;
 123         return vm_unmapped_area(&info);
 124 }
 125
 126 unsigned long
 127 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 128                           const unsigned long len, const unsigned long pgoff,
 129                           const unsigned long flags)
 130 {
 131         struct vm_area_struct *vma;
 132         struct mm_struct *mm = current->mm;
 133         unsigned long addr = addr0;
 134         struct vm_unmapped_area_info info;
 135         int do_color_align;
 136
 137         /* requested length too big for entire address space */
 138         if (len > TASK_SIZE - mmap_min_addr)
 139                 return -ENOMEM;
 140
 141         if (flags & MAP_FIXED)
 142                 return addr;
 143
 144         /* requesting a specific address */
 145         if (addr) {
 146                 addr = PAGE_ALIGN(addr);
 147                 vma = find_vma(mm, addr);
 148                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 149                                 (!vma || addr + len <= vma->vm_start))
 150                         return addr;
 151         }
 152
 153         do_color_align = 0;
 154         if (filp || (flags & MAP_SHARED))
 155                 do_color_align = !is_32bit_task();
 156
 157         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 158         info.length = len;
 159         info.low_limit = max(PAGE_SIZE, mmap_min_addr);
 160         info.high_limit = mm->mmap_base;
 161         info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
 162         info.align_offset = pgoff << PAGE_SHIFT;
 163         addr = vm_unmapped_area(&info);
 164
 165         /*
 166          * A failed mmap() very likely causes application failure,
 167          * so fall back to the bottom-up function here. This scenario
 168          * can happen with large stack limits and large mmap()
 169          * allocations.
 170          */
 171         if (addr & ~PAGE_MASK) {
 172                 VM_BUG_ON(addr != -ENOMEM);
 173                 info.flags = 0;
 174                 info.low_limit = TASK_UNMAPPED_BASE;
 175                 info.high_limit = TASK_SIZE;
 176                 addr = vm_unmapped_area(&info);
 177         }
 178
 179         return addr;
 180 }
 181
 182 unsigned long randomize_et_dyn(void)
 183 {
 184         unsigned long base;
 185
 186         base = (STACK_TOP / 3 * 2) & (~mmap_align_mask << PAGE_SHIFT);
 187         return base + mmap_rnd();
 188 }
 189
 190 #ifndef CONFIG_64BIT
 191
 192 /*
 193  * This function, called very early during the creation of a new
 194  * process VM image, sets up which VM layout function to use:
 195  */
 196 void arch_pick_mmap_layout(struct mm_struct *mm)
 197 {
 198         /*
 199          * Fall back to the standard layout if the personality
 200          * bit is set, or if the expected stack growth is unlimited:
 201          */
 202         if (mmap_is_legacy()) {
 203                 mm->mmap_base = mmap_base_legacy();
 204                 mm->get_unmapped_area = arch_get_unmapped_area;
 205         } else {
 206                 mm->mmap_base = mmap_base();
 207                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 208         }
 209 }
 210
 211 #else
 212
 213 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 214 {
 215         if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
 216                 return 0;
 217         if (!(flags & MAP_FIXED))
 218                 addr = 0;
 219         if ((addr + len) >= TASK_SIZE)
 220                 return crst_table_upgrade(current->mm, 1UL << 53);
 221         return 0;
 222 }
 223
 224 static unsigned long
 225 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 226                 unsigned long len, unsigned long pgoff, unsigned long flags)
 227 {
 228         struct mm_struct *mm = current->mm;
 229         unsigned long area;
 230         int rc;
 231
 232         area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 233         if (!(area & ~PAGE_MASK))
 234                 return area;
 235         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 236                 /* Upgrade the page table to 4 levels and retry. */
 237                 rc = crst_table_upgrade(mm, 1UL << 53);
 238                 if (rc)
 239                         return (unsigned long) rc;
 240                 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 241         }
 242         return area;
 243 }
 244
 245 static unsigned long
 246 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 247                           const unsigned long len, const unsigned long pgoff,
 248                           const unsigned long flags)
 249 {
 250         struct mm_struct *mm = current->mm;
 251         unsigned long area;
 252         int rc;
 253
 254         area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 255         if (!(area & ~PAGE_MASK))
 256                 return area;
 257         if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 258                 /* Upgrade the page table to 4 levels and retry. */
 259                 rc = crst_table_upgrade(mm, 1UL << 53);
 260                 if (rc)
 261                         return (unsigned long) rc;
 262                 area = arch_get_unmapped_area_topdown(filp, addr, len,
 263                                                       pgoff, flags);
 264         }
 265         return area;
 266 }
 267 /*
 268  * This function, called very early during the creation of a new
 269  * process VM image, sets up which VM layout function to use:
 270  */
 271 void arch_pick_mmap_layout(struct mm_struct *mm)
 272 {
 273         /*
 274          * Fall back to the standard layout if the personality
 275          * bit is set, or if the expected stack growth is unlimited:
 276          */
 277         if (mmap_is_legacy()) {
 278                 mm->mmap_base = mmap_base_legacy();
 279                 mm->get_unmapped_area = s390_get_unmapped_area;
 280         } else {
 281                 mm->mmap_base = mmap_base();
 282                 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
 283         }
 284 }
 285
 286 static int __init setup_mmap_rnd(void)
 287 {
 288         struct cpuid cpu_id;
 289
 290         get_cpu_id(&cpu_id);
 291         switch (cpu_id.machine) {
 292         case 0x9672:
 293         case 0x2064:
 294         case 0x2066:
 295         case 0x2084:
 296         case 0x2086:
 297         case 0x2094:
 298         case 0x2096:
 299         case 0x2097:
 300         case 0x2098:
 301         case 0x2817:
 302         case 0x2818:
 303         case 0x2827:
 304         case 0x2828:
 305                 mmap_rnd_mask = 0x7ffUL;
 306                 mmap_align_mask = 0UL;
 307                 break;
 308         case 0x2964:    /* z13 */
 309         default:
 310                 mmap_rnd_mask = 0x3ff80UL;
 311                 mmap_align_mask = 0x7fUL;
 312                 break;
 313         }
 314         return 0;
 315 }
 316 early_initcall(setup_mmap_rnd);
 317
 318 #endif