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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/elf-randomize.h>
11#include <linux/errno.h>
12#include <linux/mm.h>
13#include <linux/mman.h>
14#include <linux/export.h>
15#include <linux/personality.h>
16#include <linux/random.h>
17#include <linux/sched/signal.h>
18#include <linux/sched/mm.h>
19
20unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
21EXPORT_SYMBOL(shm_align_mask);
22
23/* gap between mmap and stack */
24#define MIN_GAP (128*1024*1024UL)
25#define MAX_GAP ((TASK_SIZE)/6*5)
26
27static int mmap_is_legacy(struct rlimit *rlim_stack)
28{
29 if (current->personality & ADDR_COMPAT_LAYOUT)
30 return 1;
31
32 if (rlim_stack->rlim_cur == RLIM_INFINITY)
33 return 1;
34
35 return sysctl_legacy_va_layout;
36}
37
38static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
39{
40 unsigned long gap = rlim_stack->rlim_cur;
41
42 if (gap < MIN_GAP)
43 gap = MIN_GAP;
44 else if (gap > MAX_GAP)
45 gap = MAX_GAP;
46
47 return PAGE_ALIGN(TASK_SIZE - gap - rnd);
48}
49
50#define COLOUR_ALIGN(addr, pgoff) \
51 ((((addr) + shm_align_mask) & ~shm_align_mask) + \
52 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
53
54enum mmap_allocation_direction {UP, DOWN};
55
56static unsigned long arch_get_unmapped_area_common(struct file *filp,
57 unsigned long addr0, unsigned long len, unsigned long pgoff,
58 unsigned long flags, enum mmap_allocation_direction dir)
59{
60 struct mm_struct *mm = current->mm;
61 struct vm_area_struct *vma;
62 unsigned long addr = addr0;
63 int do_color_align;
64 struct vm_unmapped_area_info info;
65
66 if (unlikely(len > TASK_SIZE))
67 return -ENOMEM;
68
69 if (flags & MAP_FIXED) {
70 /* Even MAP_FIXED mappings must reside within TASK_SIZE */
71 if (TASK_SIZE - len < addr)
72 return -EINVAL;
73
74 /*
75 * We do not accept a shared mapping if it would violate
76 * cache aliasing constraints.
77 */
78 if ((flags & MAP_SHARED) &&
79 ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
80 return -EINVAL;
81 return addr;
82 }
83
84 do_color_align = 0;
85 if (filp || (flags & MAP_SHARED))
86 do_color_align = 1;
87
88 /* requesting a specific address */
89 if (addr) {
90 if (do_color_align)
91 addr = COLOUR_ALIGN(addr, pgoff);
92 else
93 addr = PAGE_ALIGN(addr);
94
95 vma = find_vma(mm, addr);
96 if (TASK_SIZE - len >= addr &&
97 (!vma || addr + len <= vm_start_gap(vma)))
98 return addr;
99 }
100
101 info.length = len;
102 info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
103 info.align_offset = pgoff << PAGE_SHIFT;
104
105 if (dir == DOWN) {
106 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
107 info.low_limit = PAGE_SIZE;
108 info.high_limit = mm->mmap_base;
109 addr = vm_unmapped_area(&info);
110
111 if (!(addr & ~PAGE_MASK))
112 return addr;
113
114 /*
115 * A failed mmap() very likely causes application failure,
116 * so fall back to the bottom-up function here. This scenario
117 * can happen with large stack limits and large mmap()
118 * allocations.
119 */
120 }
121
122 info.flags = 0;
123 info.low_limit = mm->mmap_base;
124 info.high_limit = TASK_SIZE;
125 return vm_unmapped_area(&info);
126}
127
128unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
129 unsigned long len, unsigned long pgoff, unsigned long flags)
130{
131 return arch_get_unmapped_area_common(filp,
132 addr0, len, pgoff, flags, UP);
133}
134
135/*
136 * There is no need to export this but sched.h declares the function as
137 * extern so making it static here results in an error.
138 */
139unsigned long arch_get_unmapped_area_topdown(struct file *filp,
140 unsigned long addr0, unsigned long len, unsigned long pgoff,
141 unsigned long flags)
142{
143 return arch_get_unmapped_area_common(filp,
144 addr0, len, pgoff, flags, DOWN);
145}
146
147unsigned long arch_mmap_rnd(void)
148{
149 unsigned long rnd;
150
151#ifdef CONFIG_COMPAT
152 if (TASK_IS_32BIT_ADDR)
153 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
154 else
155#endif /* CONFIG_COMPAT */
156 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
157
158 return rnd << PAGE_SHIFT;
159}
160
161void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
162{
163 unsigned long random_factor = 0UL;
164
165 if (current->flags & PF_RANDOMIZE)
166 random_factor = arch_mmap_rnd();
167
168 if (mmap_is_legacy(rlim_stack)) {
169 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
170 mm->get_unmapped_area = arch_get_unmapped_area;
171 } else {
172 mm->mmap_base = mmap_base(random_factor, rlim_stack);
173 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
174 }
175}
176
177static inline unsigned long brk_rnd(void)
178{
179 unsigned long rnd = get_random_long();
180
181 rnd = rnd << PAGE_SHIFT;
182 /* 8MB for 32bit, 256MB for 64bit */
183 if (TASK_IS_32BIT_ADDR)
184 rnd = rnd & 0x7ffffful;
185 else
186 rnd = rnd & 0xffffffful;
187
188 return rnd;
189}
190
191unsigned long arch_randomize_brk(struct mm_struct *mm)
192{
193 unsigned long base = mm->brk;
194 unsigned long ret;
195
196 ret = PAGE_ALIGN(base + brk_rnd());
197
198 if (ret < mm->brk)
199 return mm->brk;
200
201 return ret;
202}
203
204int __virt_addr_valid(const volatile void *kaddr)
205{
206 return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
207}
208EXPORT_SYMBOL_GPL(__virt_addr_valid);