Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
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> | |
638ad34a | 27 | #include <linux/mman.h> |
1da177e4 | 28 | #include <linux/module.h> |
df1ca53c | 29 | #include <linux/random.h> |
048cd4e5 | 30 | #include <linux/compat.h> |
6252d702 | 31 | #include <asm/pgalloc.h> |
1da177e4 | 32 | |
9046e401 HC |
33 | static unsigned long stack_maxrandom_size(void) |
34 | { | |
35 | if (!(current->flags & PF_RANDOMIZE)) | |
36 | return 0; | |
37 | if (current->personality & ADDR_NO_RANDOMIZE) | |
38 | return 0; | |
39 | return STACK_RND_MASK << PAGE_SHIFT; | |
40 | } | |
41 | ||
1da177e4 LT |
42 | /* |
43 | * Top of mmap area (just below the process stack). | |
44 | * | |
9e78a13b | 45 | * Leave at least a ~32 MB hole. |
1da177e4 | 46 | */ |
9e78a13b | 47 | #define MIN_GAP (32*1024*1024) |
f481bfaf | 48 | #define MAX_GAP (STACK_TOP/6*5) |
1da177e4 | 49 | |
1060f62e HC |
50 | static inline int mmap_is_legacy(void) |
51 | { | |
52 | if (current->personality & ADDR_COMPAT_LAYOUT) | |
53 | return 1; | |
54 | if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) | |
55 | return 1; | |
56 | return sysctl_legacy_va_layout; | |
57 | } | |
58 | ||
df1ca53c HC |
59 | static unsigned long mmap_rnd(void) |
60 | { | |
61 | if (!(current->flags & PF_RANDOMIZE)) | |
62 | return 0; | |
63 | /* 8MB randomization for mmap_base */ | |
64 | return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; | |
65 | } | |
66 | ||
7aba842f HC |
67 | static unsigned long mmap_base_legacy(void) |
68 | { | |
69 | return TASK_UNMAPPED_BASE + mmap_rnd(); | |
70 | } | |
71 | ||
1da177e4 LT |
72 | static inline unsigned long mmap_base(void) |
73 | { | |
a58c26bb | 74 | unsigned long gap = rlimit(RLIMIT_STACK); |
1da177e4 LT |
75 | |
76 | if (gap < MIN_GAP) | |
77 | gap = MIN_GAP; | |
78 | else if (gap > MAX_GAP) | |
79 | gap = MAX_GAP; | |
df1ca53c HC |
80 | gap &= PAGE_MASK; |
81 | return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap; | |
1da177e4 LT |
82 | } |
83 | ||
6252d702 MS |
84 | #ifndef CONFIG_64BIT |
85 | ||
1da177e4 LT |
86 | /* |
87 | * This function, called very early during the creation of a new | |
88 | * process VM image, sets up which VM layout function to use: | |
89 | */ | |
90 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
91 | { | |
92 | /* | |
93 | * Fall back to the standard layout if the personality | |
94 | * bit is set, or if the expected stack growth is unlimited: | |
95 | */ | |
96 | if (mmap_is_legacy()) { | |
7aba842f | 97 | mm->mmap_base = mmap_base_legacy(); |
1da177e4 | 98 | mm->get_unmapped_area = arch_get_unmapped_area; |
1da177e4 LT |
99 | } else { |
100 | mm->mmap_base = mmap_base(); | |
101 | mm->get_unmapped_area = arch_get_unmapped_area_topdown; | |
1da177e4 LT |
102 | } |
103 | } | |
1da177e4 | 104 | |
6252d702 MS |
105 | #else |
106 | ||
486c0a0b | 107 | int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags) |
0fb1d9bc | 108 | { |
486c0a0b HB |
109 | if (is_compat_task() || (TASK_SIZE >= (1UL << 53))) |
110 | return 0; | |
111 | if (!(flags & MAP_FIXED)) | |
112 | addr = 0; | |
10607864 MS |
113 | if ((addr + len) >= TASK_SIZE) |
114 | return crst_table_upgrade(current->mm, 1UL << 53); | |
0fb1d9bc MS |
115 | return 0; |
116 | } | |
117 | ||
6252d702 MS |
118 | static unsigned long |
119 | s390_get_unmapped_area(struct file *filp, unsigned long addr, | |
120 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
121 | { | |
122 | struct mm_struct *mm = current->mm; | |
0fb1d9bc | 123 | unsigned long area; |
6252d702 MS |
124 | int rc; |
125 | ||
0fb1d9bc MS |
126 | area = arch_get_unmapped_area(filp, addr, len, pgoff, flags); |
127 | if (!(area & ~PAGE_MASK)) | |
128 | return area; | |
7757591a | 129 | if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) { |
0fb1d9bc MS |
130 | /* Upgrade the page table to 4 levels and retry. */ |
131 | rc = crst_table_upgrade(mm, 1UL << 53); | |
6252d702 MS |
132 | if (rc) |
133 | return (unsigned long) rc; | |
0fb1d9bc | 134 | area = arch_get_unmapped_area(filp, addr, len, pgoff, flags); |
6252d702 | 135 | } |
0fb1d9bc | 136 | return area; |
6252d702 MS |
137 | } |
138 | ||
139 | static unsigned long | |
0fb1d9bc | 140 | s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr, |
6252d702 MS |
141 | const unsigned long len, const unsigned long pgoff, |
142 | const unsigned long flags) | |
143 | { | |
144 | struct mm_struct *mm = current->mm; | |
0fb1d9bc | 145 | unsigned long area; |
6252d702 MS |
146 | int rc; |
147 | ||
0fb1d9bc MS |
148 | area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); |
149 | if (!(area & ~PAGE_MASK)) | |
150 | return area; | |
7757591a | 151 | if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) { |
0fb1d9bc MS |
152 | /* Upgrade the page table to 4 levels and retry. */ |
153 | rc = crst_table_upgrade(mm, 1UL << 53); | |
6252d702 MS |
154 | if (rc) |
155 | return (unsigned long) rc; | |
0fb1d9bc MS |
156 | area = arch_get_unmapped_area_topdown(filp, addr, len, |
157 | pgoff, flags); | |
6252d702 | 158 | } |
0fb1d9bc | 159 | return area; |
6252d702 MS |
160 | } |
161 | /* | |
162 | * This function, called very early during the creation of a new | |
163 | * process VM image, sets up which VM layout function to use: | |
164 | */ | |
165 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
166 | { | |
167 | /* | |
168 | * Fall back to the standard layout if the personality | |
169 | * bit is set, or if the expected stack growth is unlimited: | |
170 | */ | |
171 | if (mmap_is_legacy()) { | |
7aba842f | 172 | mm->mmap_base = mmap_base_legacy(); |
6252d702 | 173 | mm->get_unmapped_area = s390_get_unmapped_area; |
6252d702 MS |
174 | } else { |
175 | mm->mmap_base = mmap_base(); | |
176 | mm->get_unmapped_area = s390_get_unmapped_area_topdown; | |
6252d702 MS |
177 | } |
178 | } | |
6252d702 MS |
179 | |
180 | #endif |