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 | ||
25 | static pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr) | |
26 | { | |
27 | pgd_t *pgd; | |
28 | pud_t *pud; | |
29 | pmd_t *pmd; | |
30 | pte_t *pte = NULL; | |
31 | ||
32 | pgd = pgd_offset(mm, addr); | |
33 | if (pgd_none_or_clear_bad(pgd)) | |
34 | goto end; | |
35 | ||
36 | pud = pud_offset(pgd, addr); | |
37 | if (pud_none_or_clear_bad(pud)) | |
38 | goto end; | |
39 | ||
40 | pmd = pmd_offset(pud, addr); | |
41 | if (pmd_none_or_clear_bad(pmd)) | |
42 | goto end; | |
43 | ||
44 | pte = pte_offset_map_nested(pmd, addr); | |
45 | if (pte_none(*pte)) { | |
46 | pte_unmap_nested(pte); | |
47 | pte = NULL; | |
48 | } | |
49 | end: | |
50 | return pte; | |
51 | } | |
52 | ||
53 | static pte_t *get_one_pte_map(struct mm_struct *mm, unsigned long addr) | |
54 | { | |
55 | pgd_t *pgd; | |
56 | pud_t *pud; | |
57 | pmd_t *pmd; | |
58 | ||
59 | pgd = pgd_offset(mm, addr); | |
60 | if (pgd_none_or_clear_bad(pgd)) | |
61 | return NULL; | |
62 | ||
63 | pud = pud_offset(pgd, addr); | |
64 | if (pud_none_or_clear_bad(pud)) | |
65 | return NULL; | |
66 | ||
67 | pmd = pmd_offset(pud, addr); | |
68 | if (pmd_none_or_clear_bad(pmd)) | |
69 | return NULL; | |
70 | ||
71 | return pte_offset_map(pmd, addr); | |
72 | } | |
73 | ||
74 | static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr) | |
75 | { | |
76 | pgd_t *pgd; | |
77 | pud_t *pud; | |
78 | pmd_t *pmd; | |
79 | pte_t *pte = NULL; | |
80 | ||
81 | pgd = pgd_offset(mm, addr); | |
82 | ||
83 | pud = pud_alloc(mm, pgd, addr); | |
84 | if (!pud) | |
85 | return NULL; | |
86 | pmd = pmd_alloc(mm, pud, addr); | |
87 | if (pmd) | |
88 | pte = pte_alloc_map(mm, pmd, addr); | |
89 | return pte; | |
90 | } | |
91 | ||
92 | static int | |
93 | move_one_page(struct vm_area_struct *vma, unsigned long old_addr, | |
94 | struct vm_area_struct *new_vma, unsigned long new_addr) | |
95 | { | |
96 | struct address_space *mapping = NULL; | |
97 | struct mm_struct *mm = vma->vm_mm; | |
98 | int error = 0; | |
99 | pte_t *src, *dst; | |
100 | ||
101 | if (vma->vm_file) { | |
102 | /* | |
103 | * Subtle point from Rajesh Venkatasubramanian: before | |
104 | * moving file-based ptes, we must lock vmtruncate out, | |
105 | * since it might clean the dst vma before the src vma, | |
106 | * and we propagate stale pages into the dst afterward. | |
107 | */ | |
108 | mapping = vma->vm_file->f_mapping; | |
109 | spin_lock(&mapping->i_mmap_lock); | |
110 | if (new_vma->vm_truncate_count && | |
111 | new_vma->vm_truncate_count != vma->vm_truncate_count) | |
112 | new_vma->vm_truncate_count = 0; | |
113 | } | |
114 | spin_lock(&mm->page_table_lock); | |
115 | ||
116 | src = get_one_pte_map_nested(mm, old_addr); | |
117 | if (src) { | |
118 | /* | |
119 | * Look to see whether alloc_one_pte_map needs to perform a | |
120 | * memory allocation. If it does then we need to drop the | |
121 | * atomic kmap | |
122 | */ | |
123 | dst = get_one_pte_map(mm, new_addr); | |
124 | if (unlikely(!dst)) { | |
125 | pte_unmap_nested(src); | |
126 | if (mapping) | |
127 | spin_unlock(&mapping->i_mmap_lock); | |
128 | dst = alloc_one_pte_map(mm, new_addr); | |
129 | if (mapping && !spin_trylock(&mapping->i_mmap_lock)) { | |
130 | spin_unlock(&mm->page_table_lock); | |
131 | spin_lock(&mapping->i_mmap_lock); | |
132 | spin_lock(&mm->page_table_lock); | |
133 | } | |
134 | src = get_one_pte_map_nested(mm, old_addr); | |
135 | } | |
136 | /* | |
137 | * Since alloc_one_pte_map can drop and re-acquire | |
138 | * page_table_lock, we should re-check the src entry... | |
139 | */ | |
140 | if (src) { | |
141 | if (dst) { | |
142 | pte_t pte; | |
143 | pte = ptep_clear_flush(vma, old_addr, src); | |
8b1f3124 | 144 | |
9a61c349 | 145 | /* ZERO_PAGE can be dependant on virtual addr */ |
8b1f3124 NP |
146 | pte = move_pte(pte, new_vma->vm_page_prot, |
147 | old_addr, new_addr); | |
1da177e4 LT |
148 | set_pte_at(mm, new_addr, dst, pte); |
149 | } else | |
150 | error = -ENOMEM; | |
151 | pte_unmap_nested(src); | |
152 | } | |
153 | if (dst) | |
154 | pte_unmap(dst); | |
155 | } | |
156 | spin_unlock(&mm->page_table_lock); | |
157 | if (mapping) | |
158 | spin_unlock(&mapping->i_mmap_lock); | |
159 | return error; | |
160 | } | |
161 | ||
162 | static unsigned long move_page_tables(struct vm_area_struct *vma, | |
163 | unsigned long old_addr, struct vm_area_struct *new_vma, | |
164 | unsigned long new_addr, unsigned long len) | |
165 | { | |
166 | unsigned long offset; | |
167 | ||
168 | flush_cache_range(vma, old_addr, old_addr + len); | |
169 | ||
170 | /* | |
171 | * This is not the clever way to do this, but we're taking the | |
172 | * easy way out on the assumption that most remappings will be | |
173 | * only a few pages.. This also makes error recovery easier. | |
174 | */ | |
175 | for (offset = 0; offset < len; offset += PAGE_SIZE) { | |
176 | if (move_one_page(vma, old_addr + offset, | |
177 | new_vma, new_addr + offset) < 0) | |
178 | break; | |
179 | cond_resched(); | |
180 | } | |
181 | return offset; | |
182 | } | |
183 | ||
184 | static unsigned long move_vma(struct vm_area_struct *vma, | |
185 | unsigned long old_addr, unsigned long old_len, | |
186 | unsigned long new_len, unsigned long new_addr) | |
187 | { | |
188 | struct mm_struct *mm = vma->vm_mm; | |
189 | struct vm_area_struct *new_vma; | |
190 | unsigned long vm_flags = vma->vm_flags; | |
191 | unsigned long new_pgoff; | |
192 | unsigned long moved_len; | |
193 | unsigned long excess = 0; | |
194 | int split = 0; | |
195 | ||
196 | /* | |
197 | * We'd prefer to avoid failure later on in do_munmap: | |
198 | * which may split one vma into three before unmapping. | |
199 | */ | |
200 | if (mm->map_count >= sysctl_max_map_count - 3) | |
201 | return -ENOMEM; | |
202 | ||
203 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); | |
204 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); | |
205 | if (!new_vma) | |
206 | return -ENOMEM; | |
207 | ||
208 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); | |
209 | if (moved_len < old_len) { | |
210 | /* | |
211 | * On error, move entries back from new area to old, | |
212 | * which will succeed since page tables still there, | |
213 | * and then proceed to unmap new area instead of old. | |
214 | */ | |
215 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); | |
216 | vma = new_vma; | |
217 | old_len = new_len; | |
218 | old_addr = new_addr; | |
219 | new_addr = -ENOMEM; | |
220 | } | |
221 | ||
222 | /* Conceal VM_ACCOUNT so old reservation is not undone */ | |
223 | if (vm_flags & VM_ACCOUNT) { | |
224 | vma->vm_flags &= ~VM_ACCOUNT; | |
225 | excess = vma->vm_end - vma->vm_start - old_len; | |
226 | if (old_addr > vma->vm_start && | |
227 | old_addr + old_len < vma->vm_end) | |
228 | split = 1; | |
229 | } | |
230 | ||
71799062 KK |
231 | /* |
232 | * if we failed to move page tables we still do total_vm increment | |
233 | * since do_munmap() will decrement it by old_len == new_len | |
234 | */ | |
235 | mm->total_vm += new_len >> PAGE_SHIFT; | |
1c5ad845 | 236 | __vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
71799062 | 237 | |
1da177e4 LT |
238 | if (do_munmap(mm, old_addr, old_len) < 0) { |
239 | /* OOM: unable to split vma, just get accounts right */ | |
240 | vm_unacct_memory(excess >> PAGE_SHIFT); | |
241 | excess = 0; | |
242 | } | |
243 | ||
244 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ | |
245 | if (excess) { | |
246 | vma->vm_flags |= VM_ACCOUNT; | |
247 | if (split) | |
248 | vma->vm_next->vm_flags |= VM_ACCOUNT; | |
249 | } | |
250 | ||
1da177e4 LT |
251 | if (vm_flags & VM_LOCKED) { |
252 | mm->locked_vm += new_len >> PAGE_SHIFT; | |
253 | if (new_len > old_len) | |
254 | make_pages_present(new_addr + old_len, | |
255 | new_addr + new_len); | |
256 | } | |
257 | ||
258 | return new_addr; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Expand (or shrink) an existing mapping, potentially moving it at the | |
263 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) | |
264 | * | |
265 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise | |
266 | * This option implies MREMAP_MAYMOVE. | |
267 | */ | |
268 | unsigned long do_mremap(unsigned long addr, | |
269 | unsigned long old_len, unsigned long new_len, | |
270 | unsigned long flags, unsigned long new_addr) | |
271 | { | |
272 | struct vm_area_struct *vma; | |
273 | unsigned long ret = -EINVAL; | |
274 | unsigned long charged = 0; | |
275 | ||
276 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) | |
277 | goto out; | |
278 | ||
279 | if (addr & ~PAGE_MASK) | |
280 | goto out; | |
281 | ||
282 | old_len = PAGE_ALIGN(old_len); | |
283 | new_len = PAGE_ALIGN(new_len); | |
284 | ||
285 | /* | |
286 | * We allow a zero old-len as a special case | |
287 | * for DOS-emu "duplicate shm area" thing. But | |
288 | * a zero new-len is nonsensical. | |
289 | */ | |
290 | if (!new_len) | |
291 | goto out; | |
292 | ||
293 | /* new_addr is only valid if MREMAP_FIXED is specified */ | |
294 | if (flags & MREMAP_FIXED) { | |
295 | if (new_addr & ~PAGE_MASK) | |
296 | goto out; | |
297 | if (!(flags & MREMAP_MAYMOVE)) | |
298 | goto out; | |
299 | ||
300 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) | |
301 | goto out; | |
302 | ||
303 | /* Check if the location we're moving into overlaps the | |
304 | * old location at all, and fail if it does. | |
305 | */ | |
306 | if ((new_addr <= addr) && (new_addr+new_len) > addr) | |
307 | goto out; | |
308 | ||
309 | if ((addr <= new_addr) && (addr+old_len) > new_addr) | |
310 | goto out; | |
311 | ||
312 | ret = do_munmap(current->mm, new_addr, new_len); | |
313 | if (ret) | |
314 | goto out; | |
315 | } | |
316 | ||
317 | /* | |
318 | * Always allow a shrinking remap: that just unmaps | |
319 | * the unnecessary pages.. | |
320 | * do_munmap does all the needed commit accounting | |
321 | */ | |
322 | if (old_len >= new_len) { | |
323 | ret = do_munmap(current->mm, addr+new_len, old_len - new_len); | |
324 | if (ret && old_len != new_len) | |
325 | goto out; | |
326 | ret = addr; | |
327 | if (!(flags & MREMAP_FIXED) || (new_addr == addr)) | |
328 | goto out; | |
329 | old_len = new_len; | |
330 | } | |
331 | ||
332 | /* | |
333 | * Ok, we need to grow.. or relocate. | |
334 | */ | |
335 | ret = -EFAULT; | |
336 | vma = find_vma(current->mm, addr); | |
337 | if (!vma || vma->vm_start > addr) | |
338 | goto out; | |
339 | if (is_vm_hugetlb_page(vma)) { | |
340 | ret = -EINVAL; | |
341 | goto out; | |
342 | } | |
343 | /* We can't remap across vm area boundaries */ | |
344 | if (old_len > vma->vm_end - addr) | |
345 | goto out; | |
346 | if (vma->vm_flags & VM_DONTEXPAND) { | |
347 | if (new_len > old_len) | |
348 | goto out; | |
349 | } | |
350 | if (vma->vm_flags & VM_LOCKED) { | |
351 | unsigned long locked, lock_limit; | |
352 | locked = current->mm->locked_vm << PAGE_SHIFT; | |
353 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; | |
354 | locked += new_len - old_len; | |
355 | ret = -EAGAIN; | |
356 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
357 | goto out; | |
358 | } | |
119f657c | 359 | if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) { |
360 | ret = -ENOMEM; | |
1da177e4 | 361 | goto out; |
119f657c | 362 | } |
1da177e4 LT |
363 | |
364 | if (vma->vm_flags & VM_ACCOUNT) { | |
365 | charged = (new_len - old_len) >> PAGE_SHIFT; | |
366 | if (security_vm_enough_memory(charged)) | |
367 | goto out_nc; | |
368 | } | |
369 | ||
370 | /* old_len exactly to the end of the area.. | |
371 | * And we're not relocating the area. | |
372 | */ | |
373 | if (old_len == vma->vm_end - addr && | |
374 | !((flags & MREMAP_FIXED) && (addr != new_addr)) && | |
375 | (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { | |
376 | unsigned long max_addr = TASK_SIZE; | |
377 | if (vma->vm_next) | |
378 | max_addr = vma->vm_next->vm_start; | |
379 | /* can we just expand the current mapping? */ | |
380 | if (max_addr - addr >= new_len) { | |
381 | int pages = (new_len - old_len) >> PAGE_SHIFT; | |
382 | ||
383 | vma_adjust(vma, vma->vm_start, | |
384 | addr + new_len, vma->vm_pgoff, NULL); | |
385 | ||
386 | current->mm->total_vm += pages; | |
387 | __vm_stat_account(vma->vm_mm, vma->vm_flags, | |
388 | vma->vm_file, pages); | |
389 | if (vma->vm_flags & VM_LOCKED) { | |
390 | current->mm->locked_vm += pages; | |
391 | make_pages_present(addr + old_len, | |
392 | addr + new_len); | |
393 | } | |
394 | ret = addr; | |
395 | goto out; | |
396 | } | |
397 | } | |
398 | ||
399 | /* | |
400 | * We weren't able to just expand or shrink the area, | |
401 | * we need to create a new one and move it.. | |
402 | */ | |
403 | ret = -ENOMEM; | |
404 | if (flags & MREMAP_MAYMOVE) { | |
405 | if (!(flags & MREMAP_FIXED)) { | |
406 | unsigned long map_flags = 0; | |
407 | if (vma->vm_flags & VM_MAYSHARE) | |
408 | map_flags |= MAP_SHARED; | |
409 | ||
410 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, | |
411 | vma->vm_pgoff, map_flags); | |
412 | ret = new_addr; | |
413 | if (new_addr & ~PAGE_MASK) | |
414 | goto out; | |
415 | } | |
416 | ret = move_vma(vma, addr, old_len, new_len, new_addr); | |
417 | } | |
418 | out: | |
419 | if (ret & ~PAGE_MASK) | |
420 | vm_unacct_memory(charged); | |
421 | out_nc: | |
422 | return ret; | |
423 | } | |
424 | ||
425 | asmlinkage unsigned long sys_mremap(unsigned long addr, | |
426 | unsigned long old_len, unsigned long new_len, | |
427 | unsigned long flags, unsigned long new_addr) | |
428 | { | |
429 | unsigned long ret; | |
430 | ||
431 | down_write(¤t->mm->mmap_sem); | |
432 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); | |
433 | up_write(¤t->mm->mmap_sem); | |
434 | return ret; | |
435 | } |