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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 | ||
1da177e4 LT |
67 | static inline unsigned long mmap_base(void) |
68 | { | |
a58c26bb | 69 | unsigned long gap = rlimit(RLIMIT_STACK); |
1da177e4 LT |
70 | |
71 | if (gap < MIN_GAP) | |
72 | gap = MIN_GAP; | |
73 | else if (gap > MAX_GAP) | |
74 | gap = MAX_GAP; | |
df1ca53c HC |
75 | gap &= PAGE_MASK; |
76 | return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap; | |
1da177e4 LT |
77 | } |
78 | ||
6252d702 MS |
79 | #ifndef CONFIG_64BIT |
80 | ||
1da177e4 LT |
81 | /* |
82 | * This function, called very early during the creation of a new | |
83 | * process VM image, sets up which VM layout function to use: | |
84 | */ | |
85 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
86 | { | |
87 | /* | |
88 | * Fall back to the standard layout if the personality | |
89 | * bit is set, or if the expected stack growth is unlimited: | |
90 | */ | |
91 | if (mmap_is_legacy()) { | |
92 | mm->mmap_base = TASK_UNMAPPED_BASE; | |
93 | mm->get_unmapped_area = arch_get_unmapped_area; | |
1da177e4 LT |
94 | } else { |
95 | mm->mmap_base = mmap_base(); | |
96 | mm->get_unmapped_area = arch_get_unmapped_area_topdown; | |
1da177e4 LT |
97 | } |
98 | } | |
1da177e4 | 99 | |
6252d702 MS |
100 | #else |
101 | ||
486c0a0b | 102 | int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags) |
0fb1d9bc | 103 | { |
0f6f281b MS |
104 | int rc; |
105 | ||
486c0a0b HB |
106 | if (is_compat_task() || (TASK_SIZE >= (1UL << 53))) |
107 | return 0; | |
108 | if (!(flags & MAP_FIXED)) | |
109 | addr = 0; | |
110 | if ((addr + len) >= TASK_SIZE) { | |
0f6f281b MS |
111 | rc = crst_table_upgrade(current->mm, 1UL << 53); |
112 | if (rc) | |
113 | return rc; | |
114 | update_mm(current->mm, current); | |
115 | } | |
0fb1d9bc MS |
116 | return 0; |
117 | } | |
118 | ||
6252d702 MS |
119 | static unsigned long |
120 | s390_get_unmapped_area(struct file *filp, unsigned long addr, | |
121 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
122 | { | |
123 | struct mm_struct *mm = current->mm; | |
0fb1d9bc | 124 | unsigned long area; |
6252d702 MS |
125 | int rc; |
126 | ||
0fb1d9bc MS |
127 | area = arch_get_unmapped_area(filp, addr, len, pgoff, flags); |
128 | if (!(area & ~PAGE_MASK)) | |
129 | return area; | |
7757591a | 130 | if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) { |
0fb1d9bc MS |
131 | /* Upgrade the page table to 4 levels and retry. */ |
132 | rc = crst_table_upgrade(mm, 1UL << 53); | |
6252d702 MS |
133 | if (rc) |
134 | return (unsigned long) rc; | |
0f6f281b | 135 | update_mm(mm, current); |
0fb1d9bc | 136 | area = arch_get_unmapped_area(filp, addr, len, pgoff, flags); |
6252d702 | 137 | } |
0fb1d9bc | 138 | return area; |
6252d702 MS |
139 | } |
140 | ||
141 | static unsigned long | |
0fb1d9bc | 142 | s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr, |
6252d702 MS |
143 | const unsigned long len, const unsigned long pgoff, |
144 | const unsigned long flags) | |
145 | { | |
146 | struct mm_struct *mm = current->mm; | |
0fb1d9bc | 147 | unsigned long area; |
6252d702 MS |
148 | int rc; |
149 | ||
0fb1d9bc MS |
150 | area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); |
151 | if (!(area & ~PAGE_MASK)) | |
152 | return area; | |
7757591a | 153 | if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) { |
0fb1d9bc MS |
154 | /* Upgrade the page table to 4 levels and retry. */ |
155 | rc = crst_table_upgrade(mm, 1UL << 53); | |
6252d702 MS |
156 | if (rc) |
157 | return (unsigned long) rc; | |
0f6f281b | 158 | update_mm(mm, current); |
0fb1d9bc MS |
159 | area = arch_get_unmapped_area_topdown(filp, addr, len, |
160 | pgoff, flags); | |
6252d702 | 161 | } |
0fb1d9bc | 162 | return area; |
6252d702 MS |
163 | } |
164 | /* | |
165 | * This function, called very early during the creation of a new | |
166 | * process VM image, sets up which VM layout function to use: | |
167 | */ | |
168 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
169 | { | |
170 | /* | |
171 | * Fall back to the standard layout if the personality | |
172 | * bit is set, or if the expected stack growth is unlimited: | |
173 | */ | |
174 | if (mmap_is_legacy()) { | |
175 | mm->mmap_base = TASK_UNMAPPED_BASE; | |
176 | mm->get_unmapped_area = s390_get_unmapped_area; | |
6252d702 MS |
177 | } else { |
178 | mm->mmap_base = mmap_base(); | |
179 | mm->get_unmapped_area = s390_get_unmapped_area_topdown; | |
6252d702 MS |
180 | } |
181 | } | |
6252d702 MS |
182 | |
183 | #endif |