blob: 353037699512ca5515b11ce8fb2c808eb6386c78 [file] [log] [blame]
Ralf Baechle6f6c3c32011-05-19 09:21:33 +01001/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2011 Wind River Systems,
7 * written by Ralf Baechle <ralf@linux-mips.org>
8 */
Kevin Cernekee16650102011-06-18 11:28:48 -07009#include <linux/compiler.h>
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010010#include <linux/errno.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include <linux/module.h>
Jian Pengd0be89f2011-05-17 12:27:49 -070014#include <linux/personality.h>
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010015#include <linux/random.h>
16#include <linux/sched.h>
17
18unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010019EXPORT_SYMBOL(shm_align_mask);
20
Jian Pengd0be89f2011-05-17 12:27:49 -070021/* gap between mmap and stack */
22#define MIN_GAP (128*1024*1024UL)
Kevin Cernekee16650102011-06-18 11:28:48 -070023#define MAX_GAP ((TASK_SIZE)/6*5)
Jian Pengd0be89f2011-05-17 12:27:49 -070024
25static int mmap_is_legacy(void)
26{
27 if (current->personality & ADDR_COMPAT_LAYOUT)
28 return 1;
29
30 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
31 return 1;
32
33 return sysctl_legacy_va_layout;
34}
35
36static unsigned long mmap_base(unsigned long rnd)
37{
38 unsigned long gap = rlimit(RLIMIT_STACK);
39
40 if (gap < MIN_GAP)
41 gap = MIN_GAP;
42 else if (gap > MAX_GAP)
43 gap = MAX_GAP;
44
45 return PAGE_ALIGN(TASK_SIZE - gap - rnd);
46}
47
Kevin Cernekee16650102011-06-18 11:28:48 -070048#define COLOUR_ALIGN(addr, pgoff) \
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010049 ((((addr) + shm_align_mask) & ~shm_align_mask) + \
50 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
51
Jian Pengd0be89f2011-05-17 12:27:49 -070052enum mmap_allocation_direction {UP, DOWN};
53
Kevin Cernekee16650102011-06-18 11:28:48 -070054static unsigned long arch_get_unmapped_area_common(struct file *filp,
Jian Pengd0be89f2011-05-17 12:27:49 -070055 unsigned long addr0, unsigned long len, unsigned long pgoff,
56 unsigned long flags, enum mmap_allocation_direction dir)
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010057{
Jian Pengd0be89f2011-05-17 12:27:49 -070058 struct mm_struct *mm = current->mm;
59 struct vm_area_struct *vma;
60 unsigned long addr = addr0;
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010061 int do_color_align;
Michel Lespinasseb6661862012-12-11 16:02:06 -080062 struct vm_unmapped_area_info info;
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010063
Jian Pengd0be89f2011-05-17 12:27:49 -070064 if (unlikely(len > TASK_SIZE))
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010065 return -ENOMEM;
66
67 if (flags & MAP_FIXED) {
Jian Pengd0be89f2011-05-17 12:27:49 -070068 /* Even MAP_FIXED mappings must reside within TASK_SIZE */
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010069 if (TASK_SIZE - len < addr)
70 return -EINVAL;
71
72 /*
73 * We do not accept a shared mapping if it would violate
74 * cache aliasing constraints.
75 */
76 if ((flags & MAP_SHARED) &&
77 ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
78 return -EINVAL;
79 return addr;
80 }
81
82 do_color_align = 0;
83 if (filp || (flags & MAP_SHARED))
84 do_color_align = 1;
Jian Pengd0be89f2011-05-17 12:27:49 -070085
86 /* requesting a specific address */
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010087 if (addr) {
88 if (do_color_align)
89 addr = COLOUR_ALIGN(addr, pgoff);
90 else
91 addr = PAGE_ALIGN(addr);
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010092
Jian Pengd0be89f2011-05-17 12:27:49 -070093 vma = find_vma(mm, addr);
94 if (TASK_SIZE - len >= addr &&
Kevin Cernekee16650102011-06-18 11:28:48 -070095 (!vma || addr + len <= vma->vm_start))
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010096 return addr;
Ralf Baechle6f6c3c32011-05-19 09:21:33 +010097 }
Jian Pengd0be89f2011-05-17 12:27:49 -070098
Michel Lespinasseb6661862012-12-11 16:02:06 -080099 info.length = len;
100 info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
101 info.align_offset = pgoff << PAGE_SHIFT;
Jian Pengd0be89f2011-05-17 12:27:49 -0700102
Michel Lespinasseb6661862012-12-11 16:02:06 -0800103 if (dir == DOWN) {
104 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
105 info.low_limit = PAGE_SIZE;
106 info.high_limit = mm->mmap_base;
107 addr = vm_unmapped_area(&info);
Jian Pengd0be89f2011-05-17 12:27:49 -0700108
Michel Lespinasseb6661862012-12-11 16:02:06 -0800109 if (!(addr & ~PAGE_MASK))
110 return addr;
Jian Pengd0be89f2011-05-17 12:27:49 -0700111
Jian Pengd0be89f2011-05-17 12:27:49 -0700112 /*
113 * A failed mmap() very likely causes application failure,
114 * so fall back to the bottom-up function here. This scenario
115 * can happen with large stack limits and large mmap()
116 * allocations.
117 */
Jian Pengd0be89f2011-05-17 12:27:49 -0700118 }
Michel Lespinasseb6661862012-12-11 16:02:06 -0800119
120 info.flags = 0;
121 info.low_limit = mm->mmap_base;
122 info.high_limit = TASK_SIZE;
123 return vm_unmapped_area(&info);
Jian Pengd0be89f2011-05-17 12:27:49 -0700124}
125
126unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
127 unsigned long len, unsigned long pgoff, unsigned long flags)
128{
Kevin Cernekee16650102011-06-18 11:28:48 -0700129 return arch_get_unmapped_area_common(filp,
Jian Pengd0be89f2011-05-17 12:27:49 -0700130 addr0, len, pgoff, flags, UP);
131}
132
133/*
134 * There is no need to export this but sched.h declares the function as
135 * extern so making it static here results in an error.
136 */
137unsigned long arch_get_unmapped_area_topdown(struct file *filp,
138 unsigned long addr0, unsigned long len, unsigned long pgoff,
139 unsigned long flags)
140{
Kevin Cernekee16650102011-06-18 11:28:48 -0700141 return arch_get_unmapped_area_common(filp,
Jian Pengd0be89f2011-05-17 12:27:49 -0700142 addr0, len, pgoff, flags, DOWN);
Ralf Baechle6f6c3c32011-05-19 09:21:33 +0100143}
144
Kees Cook2b68f6c2015-04-14 15:48:00 -0700145unsigned long arch_mmap_rnd(void)
Kees Cook1f0569d2015-04-14 15:47:51 -0700146{
147 unsigned long rnd;
148
Daniel Cashman5ef11c32016-02-26 15:19:37 -0800149 rnd = get_random_long();
Kees Cook1f0569d2015-04-14 15:47:51 -0700150 rnd <<= PAGE_SHIFT;
151 if (TASK_IS_32BIT_ADDR)
152 rnd &= 0xfffffful;
153 else
154 rnd &= 0xffffffful;
155
156 return rnd;
157}
158
Ralf Baechle6f6c3c32011-05-19 09:21:33 +0100159void arch_pick_mmap_layout(struct mm_struct *mm)
160{
161 unsigned long random_factor = 0UL;
162
Kees Cook1f0569d2015-04-14 15:47:51 -0700163 if (current->flags & PF_RANDOMIZE)
Kees Cook2b68f6c2015-04-14 15:48:00 -0700164 random_factor = arch_mmap_rnd();
Ralf Baechle6f6c3c32011-05-19 09:21:33 +0100165
Jian Pengd0be89f2011-05-17 12:27:49 -0700166 if (mmap_is_legacy()) {
167 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
168 mm->get_unmapped_area = arch_get_unmapped_area;
Jian Pengd0be89f2011-05-17 12:27:49 -0700169 } else {
170 mm->mmap_base = mmap_base(random_factor);
171 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
Jian Pengd0be89f2011-05-17 12:27:49 -0700172 }
Ralf Baechle6f6c3c32011-05-19 09:21:33 +0100173}
174
175static inline unsigned long brk_rnd(void)
176{
Daniel Cashman5ef11c32016-02-26 15:19:37 -0800177 unsigned long rnd = get_random_long();
Ralf Baechle6f6c3c32011-05-19 09:21:33 +0100178
179 rnd = rnd << PAGE_SHIFT;
180 /* 8MB for 32bit, 256MB for 64bit */
181 if (TASK_IS_32BIT_ADDR)
182 rnd = rnd & 0x7ffffful;
183 else
184 rnd = rnd & 0xffffffful;
185
186 return rnd;
187}
188
189unsigned long arch_randomize_brk(struct mm_struct *mm)
190{
191 unsigned long base = mm->brk;
192 unsigned long ret;
193
194 ret = PAGE_ALIGN(base + brk_rnd());
195
196 if (ret < mm->brk)
197 return mm->brk;
198
199 return ret;
200}
Steven Rostedt196897a2013-01-25 17:13:15 +0000201
202int __virt_addr_valid(const volatile void *kaddr)
203{
204 return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
205}
206EXPORT_SYMBOL_GPL(__virt_addr_valid);