1 /*
2 * linux/arch/s390/mm/mmap.c
3 *
4 * flexible mmap layout support
5 *
6 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
7 * All Rights Reserved.
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 *
23 *
24 * Started by Ingo Molnar <mingo@elte.hu>
25 */
26
27 #include <linux/personality.h>
28 #include <linux/mm.h>
29 #include <linux/mman.h>
30 #include <linux/module.h>
31 #include <linux/random.h>
32 #include <linux/compat.h>
33 #include <asm/pgalloc.h>
34
stack_maxrandom_size(void)35 static unsigned long stack_maxrandom_size(void)
36 {
37 if (!(current->flags & PF_RANDOMIZE))
38 return 0;
39 if (current->personality & ADDR_NO_RANDOMIZE)
40 return 0;
41 return STACK_RND_MASK << PAGE_SHIFT;
42 }
43
44 /*
45 * Top of mmap area (just below the process stack).
46 *
47 * Leave at least a ~32 MB hole.
48 */
49 #define MIN_GAP (32*1024*1024)
50 #define MAX_GAP (STACK_TOP/6*5)
51
mmap_is_legacy(void)52 static inline int mmap_is_legacy(void)
53 {
54 if (current->personality & ADDR_COMPAT_LAYOUT)
55 return 1;
56 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
57 return 1;
58 return sysctl_legacy_va_layout;
59 }
60
mmap_rnd(void)61 static unsigned long mmap_rnd(void)
62 {
63 if (!(current->flags & PF_RANDOMIZE))
64 return 0;
65 /* 8MB randomization for mmap_base */
66 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
67 }
68
mmap_base(void)69 static inline unsigned long mmap_base(void)
70 {
71 unsigned long gap = rlimit(RLIMIT_STACK);
72
73 if (gap < MIN_GAP)
74 gap = MIN_GAP;
75 else if (gap > MAX_GAP)
76 gap = MAX_GAP;
77 gap &= PAGE_MASK;
78 return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
79 }
80
81 #ifndef CONFIG_64BIT
82
83 /*
84 * This function, called very early during the creation of a new
85 * process VM image, sets up which VM layout function to use:
86 */
arch_pick_mmap_layout(struct mm_struct * mm)87 void arch_pick_mmap_layout(struct mm_struct *mm)
88 {
89 /*
90 * Fall back to the standard layout if the personality
91 * bit is set, or if the expected stack growth is unlimited:
92 */
93 if (mmap_is_legacy()) {
94 mm->mmap_base = TASK_UNMAPPED_BASE;
95 mm->get_unmapped_area = arch_get_unmapped_area;
96 mm->unmap_area = arch_unmap_area;
97 } else {
98 mm->mmap_base = mmap_base();
99 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
100 mm->unmap_area = arch_unmap_area_topdown;
101 }
102 }
103
104 #else
105
s390_mmap_check(unsigned long addr,unsigned long len)106 int s390_mmap_check(unsigned long addr, unsigned long len)
107 {
108 int rc;
109
110 if (!is_compat_task() &&
111 len >= TASK_SIZE && TASK_SIZE < (1UL << 53)) {
112 rc = crst_table_upgrade(current->mm, 1UL << 53);
113 if (rc)
114 return rc;
115 update_mm(current->mm, current);
116 }
117 return 0;
118 }
119
120 static unsigned long
s390_get_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)121 s390_get_unmapped_area(struct file *filp, unsigned long addr,
122 unsigned long len, unsigned long pgoff, unsigned long flags)
123 {
124 struct mm_struct *mm = current->mm;
125 unsigned long area;
126 int rc;
127
128 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
129 if (!(area & ~PAGE_MASK))
130 return area;
131 if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
132 /* Upgrade the page table to 4 levels and retry. */
133 rc = crst_table_upgrade(mm, 1UL << 53);
134 if (rc)
135 return (unsigned long) rc;
136 update_mm(mm, current);
137 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
138 }
139 return area;
140 }
141
142 static unsigned long
s390_get_unmapped_area_topdown(struct file * filp,const unsigned long addr,const unsigned long len,const unsigned long pgoff,const unsigned long flags)143 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
144 const unsigned long len, const unsigned long pgoff,
145 const unsigned long flags)
146 {
147 struct mm_struct *mm = current->mm;
148 unsigned long area;
149 int rc;
150
151 area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
152 if (!(area & ~PAGE_MASK))
153 return area;
154 if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
155 /* Upgrade the page table to 4 levels and retry. */
156 rc = crst_table_upgrade(mm, 1UL << 53);
157 if (rc)
158 return (unsigned long) rc;
159 update_mm(mm, current);
160 area = arch_get_unmapped_area_topdown(filp, addr, len,
161 pgoff, flags);
162 }
163 return area;
164 }
165 /*
166 * This function, called very early during the creation of a new
167 * process VM image, sets up which VM layout function to use:
168 */
arch_pick_mmap_layout(struct mm_struct * mm)169 void arch_pick_mmap_layout(struct mm_struct *mm)
170 {
171 /*
172 * Fall back to the standard layout if the personality
173 * bit is set, or if the expected stack growth is unlimited:
174 */
175 if (mmap_is_legacy()) {
176 mm->mmap_base = TASK_UNMAPPED_BASE;
177 mm->get_unmapped_area = s390_get_unmapped_area;
178 mm->unmap_area = arch_unmap_area;
179 } else {
180 mm->mmap_base = mmap_base();
181 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
182 mm->unmap_area = arch_unmap_area_topdown;
183 }
184 }
185
186 #endif
187