Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/upstream-linus
[linux-2.6.git] / arch / mips / mm / mmap.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2011 Wind River Systems,
7  *   written by Ralf Baechle <ralf@linux-mips.org>
8  */
9 #include <linux/errno.h>
10 #include <linux/mm.h>
11 #include <linux/mman.h>
12 #include <linux/module.h>
13 #include <linux/personality.h>
14 #include <linux/random.h>
15 #include <linux/sched.h>
16
17 unsigned long shm_align_mask = PAGE_SIZE - 1;   /* Sane caches */
18
19 EXPORT_SYMBOL(shm_align_mask);
20
21 /* gap between mmap and stack */
22 #define MIN_GAP (128*1024*1024UL)
23 #define MAX_GAP        ((TASK_SIZE)/6*5)
24
25 static int mmap_is_legacy(void)
26 {
27         if (current->personality & ADDR_COMPAT_LAYOUT)
28                 return 1;
29
30         if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
31                 return 1;
32
33         return sysctl_legacy_va_layout;
34 }
35
36 static unsigned long mmap_base(unsigned long rnd)
37 {
38         unsigned long gap = rlimit(RLIMIT_STACK);
39
40         if (gap < MIN_GAP)
41                 gap = MIN_GAP;
42         else if (gap > MAX_GAP)
43                 gap = MAX_GAP;
44
45         return PAGE_ALIGN(TASK_SIZE - gap - rnd);
46 }
47
48 static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
49                                               unsigned long pgoff)
50 {
51         unsigned long base = addr & ~shm_align_mask;
52         unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
53
54         if (base + off <= addr)
55                 return base + off;
56
57         return base - off;
58 }
59
60 #define COLOUR_ALIGN(addr,pgoff)                                \
61         ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
62          (((pgoff) << PAGE_SHIFT) & shm_align_mask))
63
64 enum mmap_allocation_direction {UP, DOWN};
65
66 static unsigned long arch_get_unmapped_area_foo(struct file *filp,
67         unsigned long addr0, unsigned long len, unsigned long pgoff,
68         unsigned long flags, enum mmap_allocation_direction dir)
69 {
70         struct mm_struct *mm = current->mm;
71         struct vm_area_struct *vma;
72         unsigned long addr = addr0;
73         int do_color_align;
74
75         if (unlikely(len > TASK_SIZE))
76                 return -ENOMEM;
77
78         if (flags & MAP_FIXED) {
79                 /* Even MAP_FIXED mappings must reside within TASK_SIZE */
80                 if (TASK_SIZE - len < addr)
81                         return -EINVAL;
82
83                 /*
84                  * We do not accept a shared mapping if it would violate
85                  * cache aliasing constraints.
86                  */
87                 if ((flags & MAP_SHARED) &&
88                     ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
89                         return -EINVAL;
90                 return addr;
91         }
92
93         do_color_align = 0;
94         if (filp || (flags & MAP_SHARED))
95                 do_color_align = 1;
96
97         /* requesting a specific address */
98         if (addr) {
99                 if (do_color_align)
100                         addr = COLOUR_ALIGN(addr, pgoff);
101                 else
102                         addr = PAGE_ALIGN(addr);
103
104                 vma = find_vma(mm, addr);
105                 if (TASK_SIZE - len >= addr &&
106                    (!vma || addr + len <= vma->vm_start))
107                         return addr;
108         }
109
110         if (dir == UP) {
111                 addr = mm->mmap_base;
112                         if (do_color_align)
113                                 addr = COLOUR_ALIGN(addr, pgoff);
114                         else
115                                 addr = PAGE_ALIGN(addr);
116
117                 for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
118                         /* At this point:  (!vma || addr < vma->vm_end). */
119                         if (TASK_SIZE - len < addr)
120                                 return -ENOMEM;
121                         if (!vma || addr + len <= vma->vm_start)
122                                 return addr;
123                         addr = vma->vm_end;
124                         if (do_color_align)
125                                 addr = COLOUR_ALIGN(addr, pgoff);
126                  }
127          } else {
128                 /* check if free_area_cache is useful for us */
129                 if (len <= mm->cached_hole_size) {
130                         mm->cached_hole_size = 0;
131                         mm->free_area_cache = mm->mmap_base;
132                 }
133
134                 /* either no address requested or can't fit in requested address hole */
135                 addr = mm->free_area_cache;
136                         if (do_color_align) {
137                                 unsigned long base =
138                                         COLOUR_ALIGN_DOWN(addr - len, pgoff);
139
140                         addr = base + len;
141                  }
142
143                 /* make sure it can fit in the remaining address space */
144                 if (likely(addr > len)) {
145                         vma = find_vma(mm, addr - len);
146                         if (!vma || addr <= vma->vm_start) {
147                                 /* remember the address as a hint for next time */
148                                 return mm->free_area_cache = addr-len;
149                         }
150                 }
151
152                 if (unlikely(mm->mmap_base < len))
153                         goto bottomup;
154
155                 addr = mm->mmap_base-len;
156                 if (do_color_align)
157                         addr = COLOUR_ALIGN_DOWN(addr, pgoff);
158
159                 do {
160                         /*
161                          * Lookup failure means no vma is above this address,
162                          * else if new region fits below vma->vm_start,
163                          * return with success:
164                          */
165                         vma = find_vma(mm, addr);
166                         if (likely(!vma || addr+len <= vma->vm_start)) {
167                                 /* remember the address as a hint for next time */
168                                 return mm->free_area_cache = addr;
169                         }
170
171                         /* remember the largest hole we saw so far */
172                         if (addr + mm->cached_hole_size < vma->vm_start)
173                                 mm->cached_hole_size = vma->vm_start - addr;
174
175                         /* try just below the current vma->vm_start */
176                         addr = vma->vm_start-len;
177                         if (do_color_align)
178                                 addr = COLOUR_ALIGN_DOWN(addr, pgoff);
179                 } while (likely(len < vma->vm_start));
180
181 bottomup:
182                 /*
183                  * A failed mmap() very likely causes application failure,
184                  * so fall back to the bottom-up function here. This scenario
185                  * can happen with large stack limits and large mmap()
186                  * allocations.
187                  */
188                 mm->cached_hole_size = ~0UL;
189                 mm->free_area_cache = TASK_UNMAPPED_BASE;
190                 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
191                 /*
192                  * Restore the topdown base:
193                  */
194                 mm->free_area_cache = mm->mmap_base;
195                 mm->cached_hole_size = ~0UL;
196
197                 return addr;
198         }
199 }
200
201 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
202         unsigned long len, unsigned long pgoff, unsigned long flags)
203 {
204         return arch_get_unmapped_area_foo(filp,
205                         addr0, len, pgoff, flags, UP);
206 }
207
208 /*
209  * There is no need to export this but sched.h declares the function as
210  * extern so making it static here results in an error.
211  */
212 unsigned long arch_get_unmapped_area_topdown(struct file *filp,
213         unsigned long addr0, unsigned long len, unsigned long pgoff,
214         unsigned long flags)
215 {
216         return arch_get_unmapped_area_foo(filp,
217                         addr0, len, pgoff, flags, DOWN);
218 }
219
220 void arch_pick_mmap_layout(struct mm_struct *mm)
221 {
222         unsigned long random_factor = 0UL;
223
224         if (current->flags & PF_RANDOMIZE) {
225                 random_factor = get_random_int();
226                 random_factor = random_factor << PAGE_SHIFT;
227                 if (TASK_IS_32BIT_ADDR)
228                         random_factor &= 0xfffffful;
229                 else
230                         random_factor &= 0xffffffful;
231         }
232
233         if (mmap_is_legacy()) {
234                 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
235                 mm->get_unmapped_area = arch_get_unmapped_area;
236                 mm->unmap_area = arch_unmap_area;
237         } else {
238                 mm->mmap_base = mmap_base(random_factor);
239                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
240                 mm->unmap_area = arch_unmap_area_topdown;
241         }
242 }
243
244 static inline unsigned long brk_rnd(void)
245 {
246         unsigned long rnd = get_random_int();
247
248         rnd = rnd << PAGE_SHIFT;
249         /* 8MB for 32bit, 256MB for 64bit */
250         if (TASK_IS_32BIT_ADDR)
251                 rnd = rnd & 0x7ffffful;
252         else
253                 rnd = rnd & 0xffffffful;
254
255         return rnd;
256 }
257
258 unsigned long arch_randomize_brk(struct mm_struct *mm)
259 {
260         unsigned long base = mm->brk;
261         unsigned long ret;
262
263         ret = PAGE_ALIGN(base + brk_rnd());
264
265         if (ret < mm->brk)
266                 return mm->brk;
267
268         return ret;
269 }