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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * mm/mremap.c | |
3 | * | |
4 | * (C) Copyright 1996 Linus Torvalds | |
5 | * | |
6 | * Address space accounting code <alan@redhat.com> | |
7 | * (C) Copyright 2002 Red Hat Inc, All Rights Reserved | |
8 | */ | |
9 | ||
10 | #include <linux/mm.h> | |
11 | #include <linux/hugetlb.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/shm.h> | |
14 | #include <linux/mman.h> | |
15 | #include <linux/swap.h> | |
16 | #include <linux/fs.h> | |
17 | #include <linux/highmem.h> | |
18 | #include <linux/security.h> | |
19 | #include <linux/syscalls.h> | |
20 | ||
21 | #include <asm/uaccess.h> | |
22 | #include <asm/cacheflush.h> | |
23 | #include <asm/tlbflush.h> | |
24 | ||
7be7a546 | 25 | static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
26 | { |
27 | pgd_t *pgd; | |
28 | pud_t *pud; | |
29 | pmd_t *pmd; | |
30 | ||
31 | pgd = pgd_offset(mm, addr); | |
32 | if (pgd_none_or_clear_bad(pgd)) | |
33 | return NULL; | |
34 | ||
35 | pud = pud_offset(pgd, addr); | |
36 | if (pud_none_or_clear_bad(pud)) | |
37 | return NULL; | |
38 | ||
39 | pmd = pmd_offset(pud, addr); | |
40 | if (pmd_none_or_clear_bad(pmd)) | |
41 | return NULL; | |
42 | ||
7be7a546 | 43 | return pmd; |
1da177e4 LT |
44 | } |
45 | ||
7be7a546 | 46 | static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
47 | { |
48 | pgd_t *pgd; | |
49 | pud_t *pud; | |
c74df32c | 50 | pmd_t *pmd; |
1da177e4 LT |
51 | |
52 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
53 | pud = pud_alloc(mm, pgd, addr); |
54 | if (!pud) | |
c74df32c | 55 | return NULL; |
7be7a546 | 56 | |
1da177e4 | 57 | pmd = pmd_alloc(mm, pud, addr); |
7be7a546 | 58 | if (!pmd) |
c74df32c | 59 | return NULL; |
7be7a546 | 60 | |
1bb3630e | 61 | if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr)) |
c74df32c HD |
62 | return NULL; |
63 | ||
7be7a546 | 64 | return pmd; |
1da177e4 LT |
65 | } |
66 | ||
7be7a546 HD |
67 | static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, |
68 | unsigned long old_addr, unsigned long old_end, | |
69 | struct vm_area_struct *new_vma, pmd_t *new_pmd, | |
70 | unsigned long new_addr) | |
1da177e4 LT |
71 | { |
72 | struct address_space *mapping = NULL; | |
73 | struct mm_struct *mm = vma->vm_mm; | |
7be7a546 | 74 | pte_t *old_pte, *new_pte, pte; |
c74df32c | 75 | spinlock_t *old_ptl; |
1da177e4 LT |
76 | |
77 | if (vma->vm_file) { | |
78 | /* | |
79 | * Subtle point from Rajesh Venkatasubramanian: before | |
80 | * moving file-based ptes, we must lock vmtruncate out, | |
81 | * since it might clean the dst vma before the src vma, | |
82 | * and we propagate stale pages into the dst afterward. | |
83 | */ | |
84 | mapping = vma->vm_file->f_mapping; | |
85 | spin_lock(&mapping->i_mmap_lock); | |
86 | if (new_vma->vm_truncate_count && | |
87 | new_vma->vm_truncate_count != vma->vm_truncate_count) | |
88 | new_vma->vm_truncate_count = 0; | |
89 | } | |
1da177e4 | 90 | |
c74df32c HD |
91 | old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); |
92 | new_pte = pte_offset_map_nested(new_pmd, new_addr); | |
7be7a546 HD |
93 | |
94 | for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, | |
95 | new_pte++, new_addr += PAGE_SIZE) { | |
96 | if (pte_none(*old_pte)) | |
97 | continue; | |
98 | pte = ptep_clear_flush(vma, old_addr, old_pte); | |
99 | /* ZERO_PAGE can be dependant on virtual addr */ | |
100 | pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); | |
101 | set_pte_at(mm, new_addr, new_pte, pte); | |
1da177e4 | 102 | } |
7be7a546 HD |
103 | |
104 | pte_unmap_nested(new_pte - 1); | |
c74df32c | 105 | pte_unmap_unlock(old_pte - 1, old_ptl); |
1da177e4 LT |
106 | if (mapping) |
107 | spin_unlock(&mapping->i_mmap_lock); | |
1da177e4 LT |
108 | } |
109 | ||
7be7a546 HD |
110 | #define LATENCY_LIMIT (64 * PAGE_SIZE) |
111 | ||
1da177e4 LT |
112 | static unsigned long move_page_tables(struct vm_area_struct *vma, |
113 | unsigned long old_addr, struct vm_area_struct *new_vma, | |
114 | unsigned long new_addr, unsigned long len) | |
115 | { | |
7be7a546 HD |
116 | unsigned long extent, next, old_end; |
117 | pmd_t *old_pmd, *new_pmd; | |
1da177e4 | 118 | |
7be7a546 HD |
119 | old_end = old_addr + len; |
120 | flush_cache_range(vma, old_addr, old_end); | |
1da177e4 | 121 | |
7be7a546 | 122 | for (; old_addr < old_end; old_addr += extent, new_addr += extent) { |
1da177e4 | 123 | cond_resched(); |
7be7a546 HD |
124 | next = (old_addr + PMD_SIZE) & PMD_MASK; |
125 | if (next - 1 > old_end) | |
126 | next = old_end; | |
127 | extent = next - old_addr; | |
128 | old_pmd = get_old_pmd(vma->vm_mm, old_addr); | |
129 | if (!old_pmd) | |
130 | continue; | |
131 | new_pmd = alloc_new_pmd(vma->vm_mm, new_addr); | |
132 | if (!new_pmd) | |
133 | break; | |
134 | next = (new_addr + PMD_SIZE) & PMD_MASK; | |
135 | if (extent > next - new_addr) | |
136 | extent = next - new_addr; | |
137 | if (extent > LATENCY_LIMIT) | |
138 | extent = LATENCY_LIMIT; | |
139 | move_ptes(vma, old_pmd, old_addr, old_addr + extent, | |
140 | new_vma, new_pmd, new_addr); | |
1da177e4 | 141 | } |
7be7a546 HD |
142 | |
143 | return len + old_addr - old_end; /* how much done */ | |
1da177e4 LT |
144 | } |
145 | ||
146 | static unsigned long move_vma(struct vm_area_struct *vma, | |
147 | unsigned long old_addr, unsigned long old_len, | |
148 | unsigned long new_len, unsigned long new_addr) | |
149 | { | |
150 | struct mm_struct *mm = vma->vm_mm; | |
151 | struct vm_area_struct *new_vma; | |
152 | unsigned long vm_flags = vma->vm_flags; | |
153 | unsigned long new_pgoff; | |
154 | unsigned long moved_len; | |
155 | unsigned long excess = 0; | |
365e9c87 | 156 | unsigned long hiwater_vm; |
1da177e4 LT |
157 | int split = 0; |
158 | ||
159 | /* | |
160 | * We'd prefer to avoid failure later on in do_munmap: | |
161 | * which may split one vma into three before unmapping. | |
162 | */ | |
163 | if (mm->map_count >= sysctl_max_map_count - 3) | |
164 | return -ENOMEM; | |
165 | ||
166 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); | |
167 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); | |
168 | if (!new_vma) | |
169 | return -ENOMEM; | |
170 | ||
171 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); | |
172 | if (moved_len < old_len) { | |
173 | /* | |
174 | * On error, move entries back from new area to old, | |
175 | * which will succeed since page tables still there, | |
176 | * and then proceed to unmap new area instead of old. | |
177 | */ | |
178 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); | |
179 | vma = new_vma; | |
180 | old_len = new_len; | |
181 | old_addr = new_addr; | |
182 | new_addr = -ENOMEM; | |
183 | } | |
184 | ||
185 | /* Conceal VM_ACCOUNT so old reservation is not undone */ | |
186 | if (vm_flags & VM_ACCOUNT) { | |
187 | vma->vm_flags &= ~VM_ACCOUNT; | |
188 | excess = vma->vm_end - vma->vm_start - old_len; | |
189 | if (old_addr > vma->vm_start && | |
190 | old_addr + old_len < vma->vm_end) | |
191 | split = 1; | |
192 | } | |
193 | ||
71799062 | 194 | /* |
365e9c87 HD |
195 | * If we failed to move page tables we still do total_vm increment |
196 | * since do_munmap() will decrement it by old_len == new_len. | |
197 | * | |
198 | * Since total_vm is about to be raised artificially high for a | |
199 | * moment, we need to restore high watermark afterwards: if stats | |
200 | * are taken meanwhile, total_vm and hiwater_vm appear too high. | |
201 | * If this were a serious issue, we'd add a flag to do_munmap(). | |
71799062 | 202 | */ |
365e9c87 | 203 | hiwater_vm = mm->hiwater_vm; |
71799062 | 204 | mm->total_vm += new_len >> PAGE_SHIFT; |
ab50b8ed | 205 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
71799062 | 206 | |
1da177e4 LT |
207 | if (do_munmap(mm, old_addr, old_len) < 0) { |
208 | /* OOM: unable to split vma, just get accounts right */ | |
209 | vm_unacct_memory(excess >> PAGE_SHIFT); | |
210 | excess = 0; | |
211 | } | |
365e9c87 | 212 | mm->hiwater_vm = hiwater_vm; |
1da177e4 LT |
213 | |
214 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ | |
215 | if (excess) { | |
216 | vma->vm_flags |= VM_ACCOUNT; | |
217 | if (split) | |
218 | vma->vm_next->vm_flags |= VM_ACCOUNT; | |
219 | } | |
220 | ||
1da177e4 LT |
221 | if (vm_flags & VM_LOCKED) { |
222 | mm->locked_vm += new_len >> PAGE_SHIFT; | |
223 | if (new_len > old_len) | |
224 | make_pages_present(new_addr + old_len, | |
225 | new_addr + new_len); | |
226 | } | |
227 | ||
228 | return new_addr; | |
229 | } | |
230 | ||
231 | /* | |
232 | * Expand (or shrink) an existing mapping, potentially moving it at the | |
233 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) | |
234 | * | |
235 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise | |
236 | * This option implies MREMAP_MAYMOVE. | |
237 | */ | |
238 | unsigned long do_mremap(unsigned long addr, | |
239 | unsigned long old_len, unsigned long new_len, | |
240 | unsigned long flags, unsigned long new_addr) | |
241 | { | |
d0de32d9 | 242 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
243 | struct vm_area_struct *vma; |
244 | unsigned long ret = -EINVAL; | |
245 | unsigned long charged = 0; | |
246 | ||
247 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) | |
248 | goto out; | |
249 | ||
250 | if (addr & ~PAGE_MASK) | |
251 | goto out; | |
252 | ||
253 | old_len = PAGE_ALIGN(old_len); | |
254 | new_len = PAGE_ALIGN(new_len); | |
255 | ||
256 | /* | |
257 | * We allow a zero old-len as a special case | |
258 | * for DOS-emu "duplicate shm area" thing. But | |
259 | * a zero new-len is nonsensical. | |
260 | */ | |
261 | if (!new_len) | |
262 | goto out; | |
263 | ||
264 | /* new_addr is only valid if MREMAP_FIXED is specified */ | |
265 | if (flags & MREMAP_FIXED) { | |
266 | if (new_addr & ~PAGE_MASK) | |
267 | goto out; | |
268 | if (!(flags & MREMAP_MAYMOVE)) | |
269 | goto out; | |
270 | ||
271 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) | |
272 | goto out; | |
273 | ||
274 | /* Check if the location we're moving into overlaps the | |
275 | * old location at all, and fail if it does. | |
276 | */ | |
277 | if ((new_addr <= addr) && (new_addr+new_len) > addr) | |
278 | goto out; | |
279 | ||
280 | if ((addr <= new_addr) && (addr+old_len) > new_addr) | |
281 | goto out; | |
282 | ||
d0de32d9 | 283 | ret = do_munmap(mm, new_addr, new_len); |
1da177e4 LT |
284 | if (ret) |
285 | goto out; | |
286 | } | |
287 | ||
288 | /* | |
289 | * Always allow a shrinking remap: that just unmaps | |
290 | * the unnecessary pages.. | |
291 | * do_munmap does all the needed commit accounting | |
292 | */ | |
293 | if (old_len >= new_len) { | |
d0de32d9 | 294 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
1da177e4 LT |
295 | if (ret && old_len != new_len) |
296 | goto out; | |
297 | ret = addr; | |
298 | if (!(flags & MREMAP_FIXED) || (new_addr == addr)) | |
299 | goto out; | |
300 | old_len = new_len; | |
301 | } | |
302 | ||
303 | /* | |
304 | * Ok, we need to grow.. or relocate. | |
305 | */ | |
306 | ret = -EFAULT; | |
d0de32d9 | 307 | vma = find_vma(mm, addr); |
1da177e4 LT |
308 | if (!vma || vma->vm_start > addr) |
309 | goto out; | |
310 | if (is_vm_hugetlb_page(vma)) { | |
311 | ret = -EINVAL; | |
312 | goto out; | |
313 | } | |
314 | /* We can't remap across vm area boundaries */ | |
315 | if (old_len > vma->vm_end - addr) | |
316 | goto out; | |
317 | if (vma->vm_flags & VM_DONTEXPAND) { | |
318 | if (new_len > old_len) | |
319 | goto out; | |
320 | } | |
321 | if (vma->vm_flags & VM_LOCKED) { | |
322 | unsigned long locked, lock_limit; | |
d0de32d9 | 323 | locked = mm->locked_vm << PAGE_SHIFT; |
1da177e4 LT |
324 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
325 | locked += new_len - old_len; | |
326 | ret = -EAGAIN; | |
327 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
328 | goto out; | |
329 | } | |
d0de32d9 | 330 | if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) { |
119f657c | 331 | ret = -ENOMEM; |
1da177e4 | 332 | goto out; |
119f657c | 333 | } |
1da177e4 LT |
334 | |
335 | if (vma->vm_flags & VM_ACCOUNT) { | |
336 | charged = (new_len - old_len) >> PAGE_SHIFT; | |
337 | if (security_vm_enough_memory(charged)) | |
338 | goto out_nc; | |
339 | } | |
340 | ||
341 | /* old_len exactly to the end of the area.. | |
342 | * And we're not relocating the area. | |
343 | */ | |
344 | if (old_len == vma->vm_end - addr && | |
345 | !((flags & MREMAP_FIXED) && (addr != new_addr)) && | |
346 | (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { | |
347 | unsigned long max_addr = TASK_SIZE; | |
348 | if (vma->vm_next) | |
349 | max_addr = vma->vm_next->vm_start; | |
350 | /* can we just expand the current mapping? */ | |
351 | if (max_addr - addr >= new_len) { | |
352 | int pages = (new_len - old_len) >> PAGE_SHIFT; | |
353 | ||
354 | vma_adjust(vma, vma->vm_start, | |
355 | addr + new_len, vma->vm_pgoff, NULL); | |
356 | ||
d0de32d9 HD |
357 | mm->total_vm += pages; |
358 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); | |
1da177e4 | 359 | if (vma->vm_flags & VM_LOCKED) { |
d0de32d9 | 360 | mm->locked_vm += pages; |
1da177e4 LT |
361 | make_pages_present(addr + old_len, |
362 | addr + new_len); | |
363 | } | |
364 | ret = addr; | |
365 | goto out; | |
366 | } | |
367 | } | |
368 | ||
369 | /* | |
370 | * We weren't able to just expand or shrink the area, | |
371 | * we need to create a new one and move it.. | |
372 | */ | |
373 | ret = -ENOMEM; | |
374 | if (flags & MREMAP_MAYMOVE) { | |
375 | if (!(flags & MREMAP_FIXED)) { | |
376 | unsigned long map_flags = 0; | |
377 | if (vma->vm_flags & VM_MAYSHARE) | |
378 | map_flags |= MAP_SHARED; | |
379 | ||
380 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, | |
381 | vma->vm_pgoff, map_flags); | |
382 | ret = new_addr; | |
383 | if (new_addr & ~PAGE_MASK) | |
384 | goto out; | |
385 | } | |
386 | ret = move_vma(vma, addr, old_len, new_len, new_addr); | |
387 | } | |
388 | out: | |
389 | if (ret & ~PAGE_MASK) | |
390 | vm_unacct_memory(charged); | |
391 | out_nc: | |
392 | return ret; | |
393 | } | |
394 | ||
395 | asmlinkage unsigned long sys_mremap(unsigned long addr, | |
396 | unsigned long old_len, unsigned long new_len, | |
397 | unsigned long flags, unsigned long new_addr) | |
398 | { | |
399 | unsigned long ret; | |
400 | ||
401 | down_write(¤t->mm->mmap_sem); | |
402 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); | |
403 | up_write(¤t->mm->mmap_sem); | |
404 | return ret; | |
405 | } |