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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/compiler.h>
10#include <linux/errno.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include <linux/module.h>
14#include <linux/personality.h>
15#include <linux/random.h>
16#include <linux/sched.h>
17
18unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
19EXPORT_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
25static 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
36static 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
48static 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
64enum mmap_allocation_direction {UP, DOWN};
65
66static unsigned long arch_get_unmapped_area_common(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 /*
135 * either no address requested, or the mapping can't fit into
136 * the requested address hole
137 */
138 addr = mm->free_area_cache;
139 if (do_color_align) {
140 unsigned long base =
141 COLOUR_ALIGN_DOWN(addr - len, pgoff);
142 addr = base + len;
143 }
144
145 /* make sure it can fit in the remaining address space */
146 if (likely(addr > len)) {
147 vma = find_vma(mm, addr - len);
148 if (!vma || addr <= vma->vm_start) {
149 /* cache the address as a hint for next time */
150 return mm->free_area_cache = addr - len;
151 }
152 }
153
154 if (unlikely(mm->mmap_base < len))
155 goto bottomup;
156
157 addr = mm->mmap_base - len;
158 if (do_color_align)
159 addr = COLOUR_ALIGN_DOWN(addr, pgoff);
160
161 do {
162 /*
163 * Lookup failure means no vma is above this address,
164 * else if new region fits below vma->vm_start,
165 * return with success:
166 */
167 vma = find_vma(mm, addr);
168 if (likely(!vma || addr + len <= vma->vm_start)) {
169 /* cache the address as a hint for next time */
170 return mm->free_area_cache = addr;
171 }
172
173 /* remember the largest hole we saw so far */
174 if (addr + mm->cached_hole_size < vma->vm_start)
175 mm->cached_hole_size = vma->vm_start - addr;
176
177 /* try just below the current vma->vm_start */
178 addr = vma->vm_start - len;
179 if (do_color_align)
180 addr = COLOUR_ALIGN_DOWN(addr, pgoff);
181 } while (likely(len < vma->vm_start));
182
183bottomup:
184 /*
185 * A failed mmap() very likely causes application failure,
186 * so fall back to the bottom-up function here. This scenario
187 * can happen with large stack limits and large mmap()
188 * allocations.
189 */
190 mm->cached_hole_size = ~0UL;
191 mm->free_area_cache = TASK_UNMAPPED_BASE;
192 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
193 /*
194 * Restore the topdown base:
195 */
196 mm->free_area_cache = mm->mmap_base;
197 mm->cached_hole_size = ~0UL;
198
199 return addr;
200 }
201}
202
203unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
204 unsigned long len, unsigned long pgoff, unsigned long flags)
205{
206 return arch_get_unmapped_area_common(filp,
207 addr0, len, pgoff, flags, UP);
208}
209
210/*
211 * There is no need to export this but sched.h declares the function as
212 * extern so making it static here results in an error.
213 */
214unsigned long arch_get_unmapped_area_topdown(struct file *filp,
215 unsigned long addr0, unsigned long len, unsigned long pgoff,
216 unsigned long flags)
217{
218 return arch_get_unmapped_area_common(filp,
219 addr0, len, pgoff, flags, DOWN);
220}
221
222void arch_pick_mmap_layout(struct mm_struct *mm)
223{
224 unsigned long random_factor = 0UL;
225
226 if (current->flags & PF_RANDOMIZE) {
227 random_factor = get_random_int();
228 random_factor = random_factor << PAGE_SHIFT;
229 if (TASK_IS_32BIT_ADDR)
230 random_factor &= 0xfffffful;
231 else
232 random_factor &= 0xffffffful;
233 }
234
235 if (mmap_is_legacy()) {
236 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
237 mm->get_unmapped_area = arch_get_unmapped_area;
238 mm->unmap_area = arch_unmap_area;
239 } else {
240 mm->mmap_base = mmap_base(random_factor);
241 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
242 mm->unmap_area = arch_unmap_area_topdown;
243 }
244}
245
246static inline unsigned long brk_rnd(void)
247{
248 unsigned long rnd = get_random_int();
249
250 rnd = rnd << PAGE_SHIFT;
251 /* 8MB for 32bit, 256MB for 64bit */
252 if (TASK_IS_32BIT_ADDR)
253 rnd = rnd & 0x7ffffful;
254 else
255 rnd = rnd & 0xffffffful;
256
257 return rnd;
258}
259
260unsigned long arch_randomize_brk(struct mm_struct *mm)
261{
262 unsigned long base = mm->brk;
263 unsigned long ret;
264
265 ret = PAGE_ALIGN(base + brk_rnd());
266
267 if (ret < mm->brk)
268 return mm->brk;
269
270 return ret;
271}
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/compiler.h>
10#include <linux/errno.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include <linux/module.h>
14#include <linux/personality.h>
15#include <linux/random.h>
16#include <linux/sched.h>
17
18unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
19EXPORT_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
25static 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
36static 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#define COLOUR_ALIGN(addr, pgoff) \
49 ((((addr) + shm_align_mask) & ~shm_align_mask) + \
50 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
51
52enum mmap_allocation_direction {UP, DOWN};
53
54static unsigned long arch_get_unmapped_area_common(struct file *filp,
55 unsigned long addr0, unsigned long len, unsigned long pgoff,
56 unsigned long flags, enum mmap_allocation_direction dir)
57{
58 struct mm_struct *mm = current->mm;
59 struct vm_area_struct *vma;
60 unsigned long addr = addr0;
61 int do_color_align;
62 struct vm_unmapped_area_info info;
63
64 if (unlikely(len > TASK_SIZE))
65 return -ENOMEM;
66
67 if (flags & MAP_FIXED) {
68 /* Even MAP_FIXED mappings must reside within TASK_SIZE */
69 if (TASK_SIZE - len < addr)
70 return -EINVAL;
71
72 /*
73 * We do not accept a shared mapping if it would violate
74 * cache aliasing constraints.
75 */
76 if ((flags & MAP_SHARED) &&
77 ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
78 return -EINVAL;
79 return addr;
80 }
81
82 do_color_align = 0;
83 if (filp || (flags & MAP_SHARED))
84 do_color_align = 1;
85
86 /* requesting a specific address */
87 if (addr) {
88 if (do_color_align)
89 addr = COLOUR_ALIGN(addr, pgoff);
90 else
91 addr = PAGE_ALIGN(addr);
92
93 vma = find_vma(mm, addr);
94 if (TASK_SIZE - len >= addr &&
95 (!vma || addr + len <= vma->vm_start))
96 return addr;
97 }
98
99 info.length = len;
100 info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
101 info.align_offset = pgoff << PAGE_SHIFT;
102
103 if (dir == DOWN) {
104 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
105 info.low_limit = PAGE_SIZE;
106 info.high_limit = mm->mmap_base;
107 addr = vm_unmapped_area(&info);
108
109 if (!(addr & ~PAGE_MASK))
110 return addr;
111
112 /*
113 * A failed mmap() very likely causes application failure,
114 * so fall back to the bottom-up function here. This scenario
115 * can happen with large stack limits and large mmap()
116 * allocations.
117 */
118 }
119
120 info.flags = 0;
121 info.low_limit = mm->mmap_base;
122 info.high_limit = TASK_SIZE;
123 return vm_unmapped_area(&info);
124}
125
126unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
127 unsigned long len, unsigned long pgoff, unsigned long flags)
128{
129 return arch_get_unmapped_area_common(filp,
130 addr0, len, pgoff, flags, UP);
131}
132
133/*
134 * There is no need to export this but sched.h declares the function as
135 * extern so making it static here results in an error.
136 */
137unsigned long arch_get_unmapped_area_topdown(struct file *filp,
138 unsigned long addr0, unsigned long len, unsigned long pgoff,
139 unsigned long flags)
140{
141 return arch_get_unmapped_area_common(filp,
142 addr0, len, pgoff, flags, DOWN);
143}
144
145unsigned long arch_mmap_rnd(void)
146{
147 unsigned long rnd;
148
149 rnd = get_random_long();
150 rnd <<= PAGE_SHIFT;
151 if (TASK_IS_32BIT_ADDR)
152 rnd &= 0xfffffful;
153 else
154 rnd &= 0xffffffful;
155
156 return rnd;
157}
158
159void arch_pick_mmap_layout(struct mm_struct *mm)
160{
161 unsigned long random_factor = 0UL;
162
163 if (current->flags & PF_RANDOMIZE)
164 random_factor = arch_mmap_rnd();
165
166 if (mmap_is_legacy()) {
167 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
168 mm->get_unmapped_area = arch_get_unmapped_area;
169 } else {
170 mm->mmap_base = mmap_base(random_factor);
171 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
172 }
173}
174
175static inline unsigned long brk_rnd(void)
176{
177 unsigned long rnd = get_random_long();
178
179 rnd = rnd << PAGE_SHIFT;
180 /* 8MB for 32bit, 256MB for 64bit */
181 if (TASK_IS_32BIT_ADDR)
182 rnd = rnd & 0x7ffffful;
183 else
184 rnd = rnd & 0xffffffful;
185
186 return rnd;
187}
188
189unsigned long arch_randomize_brk(struct mm_struct *mm)
190{
191 unsigned long base = mm->brk;
192 unsigned long ret;
193
194 ret = PAGE_ALIGN(base + brk_rnd());
195
196 if (ret < mm->brk)
197 return mm->brk;
198
199 return ret;
200}
201
202int __virt_addr_valid(const volatile void *kaddr)
203{
204 return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
205}
206EXPORT_SYMBOL_GPL(__virt_addr_valid);