2
* linux/arch/s390/mm/mmap.c
4
* flexible mmap layout support
6
* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
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.
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.
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
24
* Started by Ingo Molnar <mingo@elte.hu>
27
#include <linux/personality.h>
29
#include <linux/mman.h>
30
#include <linux/module.h>
31
#include <linux/random.h>
32
#include <asm/pgalloc.h>
33
#include <asm/compat.h>
35
static unsigned long stack_maxrandom_size(void)
37
if (!(current->flags & PF_RANDOMIZE))
39
if (current->personality & ADDR_NO_RANDOMIZE)
41
return STACK_RND_MASK << PAGE_SHIFT;
45
* Top of mmap area (just below the process stack).
47
* Leave at least a ~32 MB hole.
49
#define MIN_GAP (32*1024*1024)
50
#define MAX_GAP (STACK_TOP/6*5)
52
static inline int mmap_is_legacy(void)
54
if (current->personality & ADDR_COMPAT_LAYOUT)
56
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
58
return sysctl_legacy_va_layout;
61
static unsigned long mmap_rnd(void)
63
if (!(current->flags & PF_RANDOMIZE))
65
/* 8MB randomization for mmap_base */
66
return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
69
static inline unsigned long mmap_base(void)
71
unsigned long gap = rlimit(RLIMIT_STACK);
75
else if (gap > MAX_GAP)
78
return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
84
* This function, called very early during the creation of a new
85
* process VM image, sets up which VM layout function to use:
87
void arch_pick_mmap_layout(struct mm_struct *mm)
90
* Fall back to the standard layout if the personality
91
* bit is set, or if the expected stack growth is unlimited:
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;
98
mm->mmap_base = mmap_base();
99
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
100
mm->unmap_area = arch_unmap_area_topdown;
103
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
107
int s390_mmap_check(unsigned long addr, unsigned long len)
109
if (!is_compat_task() &&
110
len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
111
return crst_table_upgrade(current->mm, 1UL << 53);
116
s390_get_unmapped_area(struct file *filp, unsigned long addr,
117
unsigned long len, unsigned long pgoff, unsigned long flags)
119
struct mm_struct *mm = current->mm;
123
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
124
if (!(area & ~PAGE_MASK))
126
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
127
/* Upgrade the page table to 4 levels and retry. */
128
rc = crst_table_upgrade(mm, 1UL << 53);
130
return (unsigned long) rc;
131
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
137
s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
138
const unsigned long len, const unsigned long pgoff,
139
const unsigned long flags)
141
struct mm_struct *mm = current->mm;
145
area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
146
if (!(area & ~PAGE_MASK))
148
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
149
/* Upgrade the page table to 4 levels and retry. */
150
rc = crst_table_upgrade(mm, 1UL << 53);
152
return (unsigned long) rc;
153
area = arch_get_unmapped_area_topdown(filp, addr, len,
159
* This function, called very early during the creation of a new
160
* process VM image, sets up which VM layout function to use:
162
void arch_pick_mmap_layout(struct mm_struct *mm)
165
* Fall back to the standard layout if the personality
166
* bit is set, or if the expected stack growth is unlimited:
168
if (mmap_is_legacy()) {
169
mm->mmap_base = TASK_UNMAPPED_BASE;
170
mm->get_unmapped_area = s390_get_unmapped_area;
171
mm->unmap_area = arch_unmap_area;
173
mm->mmap_base = mmap_base();
174
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
175
mm->unmap_area = arch_unmap_area_topdown;
178
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);