blob: 01fbe93eff5ca25f1143b1295da6ce7115e00bde [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/mlock.c
3 *
4 * (C) Copyright 1995 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 */
7
Randy.Dunlapc59ede72006-01-11 12:17:46 -08008#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/mman.h>
10#include <linux/mm.h>
11#include <linux/mempolicy.h>
12#include <linux/syscalls.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040013#include <linux/sched.h>
14#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040016int can_do_mlock(void)
17{
18 if (capable(CAP_IPC_LOCK))
19 return 1;
20 if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
21 return 1;
22 return 0;
23}
24EXPORT_SYMBOL(can_do_mlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
26static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
27 unsigned long start, unsigned long end, unsigned int newflags)
28{
29 struct mm_struct * mm = vma->vm_mm;
30 pgoff_t pgoff;
31 int pages;
32 int ret = 0;
33
34 if (newflags == vma->vm_flags) {
35 *prev = vma;
36 goto out;
37 }
38
39 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
40 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
41 vma->vm_file, pgoff, vma_policy(vma));
42 if (*prev) {
43 vma = *prev;
44 goto success;
45 }
46
47 *prev = vma;
48
49 if (start != vma->vm_start) {
50 ret = split_vma(mm, vma, start, 1);
51 if (ret)
52 goto out;
53 }
54
55 if (end != vma->vm_end) {
56 ret = split_vma(mm, vma, end, 0);
57 if (ret)
58 goto out;
59 }
60
61success:
62 /*
63 * vm_flags is protected by the mmap_sem held in write mode.
64 * It's okay if try_to_unmap_one unmaps a page just after we
65 * set VM_LOCKED, make_pages_present below will bring it back.
66 */
67 vma->vm_flags = newflags;
68
69 /*
70 * Keep track of amount of locked VM.
71 */
72 pages = (end - start) >> PAGE_SHIFT;
73 if (newflags & VM_LOCKED) {
74 pages = -pages;
75 if (!(newflags & VM_IO))
76 ret = make_pages_present(start, end);
77 }
78
Rik Bobbaersa3eea482006-12-06 20:32:25 -080079 mm->locked_vm -= pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -070080out:
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 return ret;
82}
83
84static int do_mlock(unsigned long start, size_t len, int on)
85{
86 unsigned long nstart, end, tmp;
87 struct vm_area_struct * vma, * prev;
88 int error;
89
90 len = PAGE_ALIGN(len);
91 end = start + len;
92 if (end < start)
93 return -EINVAL;
94 if (end == start)
95 return 0;
96 vma = find_vma_prev(current->mm, start, &prev);
97 if (!vma || vma->vm_start > start)
98 return -ENOMEM;
99
100 if (start > vma->vm_start)
101 prev = vma;
102
103 for (nstart = start ; ; ) {
104 unsigned int newflags;
105
106 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
107
108 newflags = vma->vm_flags | VM_LOCKED;
109 if (!on)
110 newflags &= ~VM_LOCKED;
111
112 tmp = vma->vm_end;
113 if (tmp > end)
114 tmp = end;
115 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
116 if (error)
117 break;
118 nstart = tmp;
119 if (nstart < prev->vm_end)
120 nstart = prev->vm_end;
121 if (nstart >= end)
122 break;
123
124 vma = prev->vm_next;
125 if (!vma || vma->vm_start != nstart) {
126 error = -ENOMEM;
127 break;
128 }
129 }
130 return error;
131}
132
133asmlinkage long sys_mlock(unsigned long start, size_t len)
134{
135 unsigned long locked;
136 unsigned long lock_limit;
137 int error = -ENOMEM;
138
139 if (!can_do_mlock())
140 return -EPERM;
141
142 down_write(&current->mm->mmap_sem);
143 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
144 start &= PAGE_MASK;
145
146 locked = len >> PAGE_SHIFT;
147 locked += current->mm->locked_vm;
148
149 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
150 lock_limit >>= PAGE_SHIFT;
151
152 /* check against resource limits */
153 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
154 error = do_mlock(start, len, 1);
155 up_write(&current->mm->mmap_sem);
156 return error;
157}
158
159asmlinkage long sys_munlock(unsigned long start, size_t len)
160{
161 int ret;
162
163 down_write(&current->mm->mmap_sem);
164 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
165 start &= PAGE_MASK;
166 ret = do_mlock(start, len, 0);
167 up_write(&current->mm->mmap_sem);
168 return ret;
169}
170
171static int do_mlockall(int flags)
172{
173 struct vm_area_struct * vma, * prev = NULL;
174 unsigned int def_flags = 0;
175
176 if (flags & MCL_FUTURE)
177 def_flags = VM_LOCKED;
178 current->mm->def_flags = def_flags;
179 if (flags == MCL_FUTURE)
180 goto out;
181
182 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
183 unsigned int newflags;
184
185 newflags = vma->vm_flags | VM_LOCKED;
186 if (!(flags & MCL_CURRENT))
187 newflags &= ~VM_LOCKED;
188
189 /* Ignore errors */
190 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
191 }
192out:
193 return 0;
194}
195
196asmlinkage long sys_mlockall(int flags)
197{
198 unsigned long lock_limit;
199 int ret = -EINVAL;
200
201 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
202 goto out;
203
204 ret = -EPERM;
205 if (!can_do_mlock())
206 goto out;
207
208 down_write(&current->mm->mmap_sem);
209
210 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
211 lock_limit >>= PAGE_SHIFT;
212
213 ret = -ENOMEM;
214 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
215 capable(CAP_IPC_LOCK))
216 ret = do_mlockall(flags);
217 up_write(&current->mm->mmap_sem);
218out:
219 return ret;
220}
221
222asmlinkage long sys_munlockall(void)
223{
224 int ret;
225
226 down_write(&current->mm->mmap_sem);
227 ret = do_mlockall(0);
228 up_write(&current->mm->mmap_sem);
229 return ret;
230}
231
232/*
233 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
234 * shm segments) get accounted against the user_struct instead.
235 */
236static DEFINE_SPINLOCK(shmlock_user_lock);
237
238int user_shm_lock(size_t size, struct user_struct *user)
239{
240 unsigned long lock_limit, locked;
241 int allowed = 0;
242
243 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
244 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700245 if (lock_limit == RLIM_INFINITY)
246 allowed = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 lock_limit >>= PAGE_SHIFT;
248 spin_lock(&shmlock_user_lock);
Herbert van den Bergh5ed44a42007-07-15 23:38:25 -0700249 if (!allowed &&
250 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 goto out;
252 get_uid(user);
253 user->locked_shm += locked;
254 allowed = 1;
255out:
256 spin_unlock(&shmlock_user_lock);
257 return allowed;
258}
259
260void user_shm_unlock(size_t size, struct user_struct *user)
261{
262 spin_lock(&shmlock_user_lock);
263 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
264 spin_unlock(&shmlock_user_lock);
265 free_uid(user);
266}