File: /usr/src/linux/mm/mlock.c
1 /*
2 * linux/mm/mlock.c
3 *
4 * (C) Copyright 1995 Linus Torvalds
5 */
6 #include <linux/slab.h>
7 #include <linux/shm.h>
8 #include <linux/mman.h>
9 #include <linux/smp_lock.h>
10 #include <linux/pagemap.h>
11
12 #include <asm/uaccess.h>
13 #include <asm/pgtable.h>
14
15 static inline int mlock_fixup_all(struct vm_area_struct * vma, int newflags)
16 {
17 spin_lock(&vma->vm_mm->page_table_lock);
18 vma->vm_flags = newflags;
19 spin_unlock(&vma->vm_mm->page_table_lock);
20 return 0;
21 }
22
23 static inline int mlock_fixup_start(struct vm_area_struct * vma,
24 unsigned long end, int newflags)
25 {
26 struct vm_area_struct * n;
27
28 n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
29 if (!n)
30 return -EAGAIN;
31 *n = *vma;
32 n->vm_end = end;
33 n->vm_flags = newflags;
34 n->vm_raend = 0;
35 if (n->vm_file)
36 get_file(n->vm_file);
37 if (n->vm_ops && n->vm_ops->open)
38 n->vm_ops->open(n);
39 vma->vm_pgoff += (end - vma->vm_start) >> PAGE_SHIFT;
40 lock_vma_mappings(vma);
41 spin_lock(&vma->vm_mm->page_table_lock);
42 vma->vm_start = end;
43 __insert_vm_struct(current->mm, n);
44 spin_unlock(&vma->vm_mm->page_table_lock);
45 unlock_vma_mappings(vma);
46 return 0;
47 }
48
49 static inline int mlock_fixup_end(struct vm_area_struct * vma,
50 unsigned long start, int newflags)
51 {
52 struct vm_area_struct * n;
53
54 n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
55 if (!n)
56 return -EAGAIN;
57 *n = *vma;
58 n->vm_start = start;
59 n->vm_pgoff += (n->vm_start - vma->vm_start) >> PAGE_SHIFT;
60 n->vm_flags = newflags;
61 n->vm_raend = 0;
62 if (n->vm_file)
63 get_file(n->vm_file);
64 if (n->vm_ops && n->vm_ops->open)
65 n->vm_ops->open(n);
66 lock_vma_mappings(vma);
67 spin_lock(&vma->vm_mm->page_table_lock);
68 vma->vm_end = start;
69 __insert_vm_struct(current->mm, n);
70 spin_unlock(&vma->vm_mm->page_table_lock);
71 unlock_vma_mappings(vma);
72 return 0;
73 }
74
75 static inline int mlock_fixup_middle(struct vm_area_struct * vma,
76 unsigned long start, unsigned long end, int newflags)
77 {
78 struct vm_area_struct * left, * right;
79
80 left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
81 if (!left)
82 return -EAGAIN;
83 right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
84 if (!right) {
85 kmem_cache_free(vm_area_cachep, left);
86 return -EAGAIN;
87 }
88 *left = *vma;
89 *right = *vma;
90 left->vm_end = start;
91 right->vm_start = end;
92 right->vm_pgoff += (right->vm_start - left->vm_start) >> PAGE_SHIFT;
93 vma->vm_flags = newflags;
94 left->vm_raend = 0;
95 right->vm_raend = 0;
96 if (vma->vm_file)
97 atomic_add(2, &vma->vm_file->f_count);
98
99 if (vma->vm_ops && vma->vm_ops->open) {
100 vma->vm_ops->open(left);
101 vma->vm_ops->open(right);
102 }
103 vma->vm_raend = 0;
104 vma->vm_pgoff += (start - vma->vm_start) >> PAGE_SHIFT;
105 lock_vma_mappings(vma);
106 spin_lock(&vma->vm_mm->page_table_lock);
107 vma->vm_start = start;
108 vma->vm_end = end;
109 vma->vm_flags = newflags;
110 __insert_vm_struct(current->mm, left);
111 __insert_vm_struct(current->mm, right);
112 spin_unlock(&vma->vm_mm->page_table_lock);
113 unlock_vma_mappings(vma);
114 return 0;
115 }
116
117 static int mlock_fixup(struct vm_area_struct * vma,
118 unsigned long start, unsigned long end, unsigned int newflags)
119 {
120 int pages, retval;
121
122 if (newflags == vma->vm_flags)
123 return 0;
124
125 if (start == vma->vm_start) {
126 if (end == vma->vm_end)
127 retval = mlock_fixup_all(vma, newflags);
128 else
129 retval = mlock_fixup_start(vma, end, newflags);
130 } else {
131 if (end == vma->vm_end)
132 retval = mlock_fixup_end(vma, start, newflags);
133 else
134 retval = mlock_fixup_middle(vma, start, end, newflags);
135 }
136 if (!retval) {
137 /* keep track of amount of locked VM */
138 pages = (end - start) >> PAGE_SHIFT;
139 if (newflags & VM_LOCKED) {
140 pages = -pages;
141 make_pages_present(start, end);
142 }
143 vma->vm_mm->locked_vm -= pages;
144 }
145 return retval;
146 }
147
148 static int do_mlock(unsigned long start, size_t len, int on)
149 {
150 unsigned long nstart, end, tmp;
151 struct vm_area_struct * vma, * next;
152 int error;
153
154 if (on && !capable(CAP_IPC_LOCK))
155 return -EPERM;
156 len = PAGE_ALIGN(len);
157 end = start + len;
158 if (end < start)
159 return -EINVAL;
160 if (end == start)
161 return 0;
162 vma = find_vma(current->mm, start);
163 if (!vma || vma->vm_start > start)
164 return -ENOMEM;
165
166 for (nstart = start ; ; ) {
167 unsigned int newflags;
168
169 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
170
171 newflags = vma->vm_flags | VM_LOCKED;
172 if (!on)
173 newflags &= ~VM_LOCKED;
174
175 if (vma->vm_end >= end) {
176 error = mlock_fixup(vma, nstart, end, newflags);
177 break;
178 }
179
180 tmp = vma->vm_end;
181 next = vma->vm_next;
182 error = mlock_fixup(vma, nstart, tmp, newflags);
183 if (error)
184 break;
185 nstart = tmp;
186 vma = next;
187 if (!vma || vma->vm_start != nstart) {
188 error = -ENOMEM;
189 break;
190 }
191 }
192 return error;
193 }
194
195 asmlinkage long sys_mlock(unsigned long start, size_t len)
196 {
197 unsigned long locked;
198 unsigned long lock_limit;
199 int error = -ENOMEM;
200
201 down_write(¤t->mm->mmap_sem);
202 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
203 start &= PAGE_MASK;
204
205 locked = len >> PAGE_SHIFT;
206 locked += current->mm->locked_vm;
207
208 lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
209 lock_limit >>= PAGE_SHIFT;
210
211 /* check against resource limits */
212 if (locked > lock_limit)
213 goto out;
214
215 /* we may lock at most half of physical memory... */
216 /* (this check is pretty bogus, but doesn't hurt) */
217 if (locked > num_physpages/2)
218 goto out;
219
220 error = do_mlock(start, len, 1);
221 out:
222 up_write(¤t->mm->mmap_sem);
223 return error;
224 }
225
226 asmlinkage long sys_munlock(unsigned long start, size_t len)
227 {
228 int ret;
229
230 down_write(¤t->mm->mmap_sem);
231 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
232 start &= PAGE_MASK;
233 ret = do_mlock(start, len, 0);
234 up_write(¤t->mm->mmap_sem);
235 return ret;
236 }
237
238 static int do_mlockall(int flags)
239 {
240 int error;
241 unsigned int def_flags;
242 struct vm_area_struct * vma;
243
244 if (!capable(CAP_IPC_LOCK))
245 return -EPERM;
246
247 def_flags = 0;
248 if (flags & MCL_FUTURE)
249 def_flags = VM_LOCKED;
250 current->mm->def_flags = def_flags;
251
252 error = 0;
253 for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
254 unsigned int newflags;
255
256 newflags = vma->vm_flags | VM_LOCKED;
257 if (!(flags & MCL_CURRENT))
258 newflags &= ~VM_LOCKED;
259 error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
260 if (error)
261 break;
262 }
263 return error;
264 }
265
266 asmlinkage long sys_mlockall(int flags)
267 {
268 unsigned long lock_limit;
269 int ret = -EINVAL;
270
271 down_write(¤t->mm->mmap_sem);
272 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
273 goto out;
274
275 lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
276 lock_limit >>= PAGE_SHIFT;
277
278 ret = -ENOMEM;
279 if (current->mm->total_vm > lock_limit)
280 goto out;
281
282 /* we may lock at most half of physical memory... */
283 /* (this check is pretty bogus, but doesn't hurt) */
284 if (current->mm->total_vm > num_physpages/2)
285 goto out;
286
287 ret = do_mlockall(flags);
288 out:
289 up_write(¤t->mm->mmap_sem);
290 return ret;
291 }
292
293 asmlinkage long sys_munlockall(void)
294 {
295 int ret;
296
297 down_write(¤t->mm->mmap_sem);
298 ret = do_mlockall(0);
299 up_write(¤t->mm->mmap_sem);
300 return ret;
301 }
302