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Linux/arch/s390/mm/mmap.c

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  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);
289 

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