Linux 4.13.16
[linux/fpc-iii.git] / arch / s390 / mm / mmap.c
blob5bea139517a2edc21dc50074d2c2e9a94dabb19e
1 /*
2 * flexible mmap layout support
4 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
5 * All Rights Reserved.
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/elf-randomize.h>
26 #include <linux/personality.h>
27 #include <linux/mm.h>
28 #include <linux/mman.h>
29 #include <linux/sched/signal.h>
30 #include <linux/sched/mm.h>
31 #include <linux/random.h>
32 #include <linux/compat.h>
33 #include <linux/security.h>
34 #include <asm/pgalloc.h>
35 #include <asm/elf.h>
37 static unsigned long stack_maxrandom_size(void)
39 if (!(current->flags & PF_RANDOMIZE))
40 return 0;
41 if (current->personality & ADDR_NO_RANDOMIZE)
42 return 0;
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)
57 return 1;
58 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
59 return 1;
60 return sysctl_legacy_va_layout;
63 unsigned long arch_mmap_rnd(void)
65 return (get_random_int() & MMAP_RND_MASK) << PAGE_SHIFT;
68 static unsigned long mmap_base_legacy(unsigned long rnd)
70 return TASK_UNMAPPED_BASE + rnd;
73 static inline unsigned long mmap_base(unsigned long rnd)
75 unsigned long gap = rlimit(RLIMIT_STACK);
77 if (gap < MIN_GAP)
78 gap = MIN_GAP;
79 else if (gap > MAX_GAP)
80 gap = MAX_GAP;
81 gap &= PAGE_MASK;
82 return STACK_TOP - stack_maxrandom_size() - rnd - gap;
85 unsigned long
86 arch_get_unmapped_area(struct file *filp, unsigned long addr,
87 unsigned long len, unsigned long pgoff, unsigned long flags)
89 struct mm_struct *mm = current->mm;
90 struct vm_area_struct *vma;
91 struct vm_unmapped_area_info info;
92 int rc;
94 if (len > TASK_SIZE - mmap_min_addr)
95 return -ENOMEM;
97 if (flags & MAP_FIXED)
98 goto check_asce_limit;
100 if (addr) {
101 addr = PAGE_ALIGN(addr);
102 vma = find_vma(mm, addr);
103 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
104 (!vma || addr + len <= vm_start_gap(vma)))
105 goto check_asce_limit;
108 info.flags = 0;
109 info.length = len;
110 info.low_limit = mm->mmap_base;
111 info.high_limit = TASK_SIZE;
112 if (filp || (flags & MAP_SHARED))
113 info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
114 else
115 info.align_mask = 0;
116 info.align_offset = pgoff << PAGE_SHIFT;
117 addr = vm_unmapped_area(&info);
118 if (addr & ~PAGE_MASK)
119 return addr;
121 check_asce_limit:
122 if (addr + len > current->mm->context.asce_limit &&
123 addr + len <= TASK_SIZE) {
124 rc = crst_table_upgrade(mm, addr + len);
125 if (rc)
126 return (unsigned long) rc;
129 return addr;
132 unsigned long
133 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
134 const unsigned long len, const unsigned long pgoff,
135 const unsigned long flags)
137 struct vm_area_struct *vma;
138 struct mm_struct *mm = current->mm;
139 unsigned long addr = addr0;
140 struct vm_unmapped_area_info info;
141 int rc;
143 /* requested length too big for entire address space */
144 if (len > TASK_SIZE - mmap_min_addr)
145 return -ENOMEM;
147 if (flags & MAP_FIXED)
148 goto check_asce_limit;
150 /* requesting a specific address */
151 if (addr) {
152 addr = PAGE_ALIGN(addr);
153 vma = find_vma(mm, addr);
154 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
155 (!vma || addr + len <= vm_start_gap(vma)))
156 goto check_asce_limit;
159 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
160 info.length = len;
161 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
162 info.high_limit = mm->mmap_base;
163 if (filp || (flags & MAP_SHARED))
164 info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
165 else
166 info.align_mask = 0;
167 info.align_offset = pgoff << PAGE_SHIFT;
168 addr = vm_unmapped_area(&info);
171 * A failed mmap() very likely causes application failure,
172 * so fall back to the bottom-up function here. This scenario
173 * can happen with large stack limits and large mmap()
174 * allocations.
176 if (addr & ~PAGE_MASK) {
177 VM_BUG_ON(addr != -ENOMEM);
178 info.flags = 0;
179 info.low_limit = TASK_UNMAPPED_BASE;
180 info.high_limit = TASK_SIZE;
181 addr = vm_unmapped_area(&info);
182 if (addr & ~PAGE_MASK)
183 return addr;
186 check_asce_limit:
187 if (addr + len > current->mm->context.asce_limit &&
188 addr + len <= TASK_SIZE) {
189 rc = crst_table_upgrade(mm, addr + len);
190 if (rc)
191 return (unsigned long) rc;
194 return addr;
198 * This function, called very early during the creation of a new
199 * process VM image, sets up which VM layout function to use:
201 void arch_pick_mmap_layout(struct mm_struct *mm)
203 unsigned long random_factor = 0UL;
205 if (current->flags & PF_RANDOMIZE)
206 random_factor = arch_mmap_rnd();
209 * Fall back to the standard layout if the personality
210 * bit is set, or if the expected stack growth is unlimited:
212 if (mmap_is_legacy()) {
213 mm->mmap_base = mmap_base_legacy(random_factor);
214 mm->get_unmapped_area = arch_get_unmapped_area;
215 } else {
216 mm->mmap_base = mmap_base(random_factor);
217 mm->get_unmapped_area = arch_get_unmapped_area_topdown;