2 * flexible mmap layout support
4 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
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.
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.
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
22 * Started by Ingo Molnar <mingo@elte.hu>
25 #include <linux/personality.h>
27 #include <linux/mman.h>
28 #include <linux/module.h>
29 #include <linux/random.h>
30 #include <linux/compat.h>
31 #include <linux/security.h>
32 #include <asm/pgalloc.h>
34 unsigned long mmap_rnd_mask;
35 static unsigned long mmap_align_mask;
37 static unsigned long stack_maxrandom_size(void)
39 if (!(current->flags & PF_RANDOMIZE))
41 if (current->personality & ADDR_NO_RANDOMIZE)
43 return STACK_RND_MASK << PAGE_SHIFT;
47 * Top of mmap area (just below the process stack).
49 * Leave at least a ~32 MB hole.
51 #define MIN_GAP (32*1024*1024)
52 #define MAX_GAP (STACK_TOP/6*5)
54 static inline int mmap_is_legacy(void)
56 if (current->personality & ADDR_COMPAT_LAYOUT)
58 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
60 return sysctl_legacy_va_layout;
63 unsigned long arch_mmap_rnd(void)
66 return (get_random_int() & 0x7ff) << PAGE_SHIFT;
68 return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
71 static unsigned long mmap_base_legacy(unsigned long rnd)
73 return TASK_UNMAPPED_BASE + rnd;
76 static inline unsigned long mmap_base(unsigned long rnd)
78 unsigned long gap = rlimit(RLIMIT_STACK);
82 else if (gap > MAX_GAP)
85 return STACK_TOP - stack_maxrandom_size() - rnd - gap;
89 arch_get_unmapped_area(struct file *filp, unsigned long addr,
90 unsigned long len, unsigned long pgoff, unsigned long flags)
92 struct mm_struct *mm = current->mm;
93 struct vm_area_struct *vma;
94 struct vm_unmapped_area_info info;
97 if (len > TASK_SIZE - mmap_min_addr)
100 if (flags & MAP_FIXED)
104 addr = PAGE_ALIGN(addr);
105 vma = find_vma(mm, addr);
106 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
107 (!vma || addr + len <= vma->vm_start))
112 if (filp || (flags & MAP_SHARED))
113 do_color_align = !is_32bit_task();
117 info.low_limit = mm->mmap_base;
118 info.high_limit = TASK_SIZE;
119 info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
120 info.align_offset = pgoff << PAGE_SHIFT;
121 return vm_unmapped_area(&info);
125 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
126 const unsigned long len, const unsigned long pgoff,
127 const unsigned long flags)
129 struct vm_area_struct *vma;
130 struct mm_struct *mm = current->mm;
131 unsigned long addr = addr0;
132 struct vm_unmapped_area_info info;
135 /* requested length too big for entire address space */
136 if (len > TASK_SIZE - mmap_min_addr)
139 if (flags & MAP_FIXED)
142 /* requesting a specific address */
144 addr = PAGE_ALIGN(addr);
145 vma = find_vma(mm, addr);
146 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
147 (!vma || addr + len <= vma->vm_start))
152 if (filp || (flags & MAP_SHARED))
153 do_color_align = !is_32bit_task();
155 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
157 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
158 info.high_limit = mm->mmap_base;
159 info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
160 info.align_offset = pgoff << PAGE_SHIFT;
161 addr = vm_unmapped_area(&info);
164 * A failed mmap() very likely causes application failure,
165 * so fall back to the bottom-up function here. This scenario
166 * can happen with large stack limits and large mmap()
169 if (addr & ~PAGE_MASK) {
170 VM_BUG_ON(addr != -ENOMEM);
172 info.low_limit = TASK_UNMAPPED_BASE;
173 info.high_limit = TASK_SIZE;
174 addr = vm_unmapped_area(&info);
180 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
182 if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
184 if (!(flags & MAP_FIXED))
186 if ((addr + len) >= TASK_SIZE)
187 return crst_table_upgrade(current->mm, 1UL << 53);
192 s390_get_unmapped_area(struct file *filp, unsigned long addr,
193 unsigned long len, unsigned long pgoff, unsigned long flags)
195 struct mm_struct *mm = current->mm;
199 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
200 if (!(area & ~PAGE_MASK))
202 if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
203 /* Upgrade the page table to 4 levels and retry. */
204 rc = crst_table_upgrade(mm, 1UL << 53);
206 return (unsigned long) rc;
207 area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
213 s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
214 const unsigned long len, const unsigned long pgoff,
215 const unsigned long flags)
217 struct mm_struct *mm = current->mm;
221 area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
222 if (!(area & ~PAGE_MASK))
224 if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
225 /* Upgrade the page table to 4 levels and retry. */
226 rc = crst_table_upgrade(mm, 1UL << 53);
228 return (unsigned long) rc;
229 area = arch_get_unmapped_area_topdown(filp, addr, len,
235 * This function, called very early during the creation of a new
236 * process VM image, sets up which VM layout function to use:
238 void arch_pick_mmap_layout(struct mm_struct *mm)
240 unsigned long random_factor = 0UL;
242 if (current->flags & PF_RANDOMIZE)
243 random_factor = arch_mmap_rnd();
246 * Fall back to the standard layout if the personality
247 * bit is set, or if the expected stack growth is unlimited:
249 if (mmap_is_legacy()) {
250 mm->mmap_base = mmap_base_legacy(random_factor);
251 mm->get_unmapped_area = s390_get_unmapped_area;
253 mm->mmap_base = mmap_base(random_factor);
254 mm->get_unmapped_area = s390_get_unmapped_area_topdown;
258 static int __init setup_mmap_rnd(void)
263 switch (cpu_id.machine) {
277 mmap_rnd_mask = 0x7ffUL;
278 mmap_align_mask = 0UL;
280 case 0x2964: /* z13 */
282 mmap_rnd_mask = 0x3ff80UL;
283 mmap_align_mask = 0x7fUL;
288 early_initcall(setup_mmap_rnd);