Commit | Line | Data |
---|---|---|
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> | |
c59ede7b | 16 | #include <linux/capability.h> |
1da177e4 LT |
17 | #include <linux/fs.h> |
18 | #include <linux/highmem.h> | |
19 | #include <linux/security.h> | |
20 | #include <linux/syscalls.h> | |
21 | ||
22 | #include <asm/uaccess.h> | |
23 | #include <asm/cacheflush.h> | |
24 | #include <asm/tlbflush.h> | |
25 | ||
7be7a546 | 26 | static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
27 | { |
28 | pgd_t *pgd; | |
29 | pud_t *pud; | |
30 | pmd_t *pmd; | |
31 | ||
32 | pgd = pgd_offset(mm, addr); | |
33 | if (pgd_none_or_clear_bad(pgd)) | |
34 | return NULL; | |
35 | ||
36 | pud = pud_offset(pgd, addr); | |
37 | if (pud_none_or_clear_bad(pud)) | |
38 | return NULL; | |
39 | ||
40 | pmd = pmd_offset(pud, addr); | |
41 | if (pmd_none_or_clear_bad(pmd)) | |
42 | return NULL; | |
43 | ||
7be7a546 | 44 | return pmd; |
1da177e4 LT |
45 | } |
46 | ||
7be7a546 | 47 | static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
48 | { |
49 | pgd_t *pgd; | |
50 | pud_t *pud; | |
c74df32c | 51 | pmd_t *pmd; |
1da177e4 LT |
52 | |
53 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
54 | pud = pud_alloc(mm, pgd, addr); |
55 | if (!pud) | |
c74df32c | 56 | return NULL; |
7be7a546 | 57 | |
1da177e4 | 58 | pmd = pmd_alloc(mm, pud, addr); |
7be7a546 | 59 | if (!pmd) |
c74df32c | 60 | return NULL; |
7be7a546 | 61 | |
1bb3630e | 62 | if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr)) |
c74df32c HD |
63 | return NULL; |
64 | ||
7be7a546 | 65 | return pmd; |
1da177e4 LT |
66 | } |
67 | ||
7be7a546 HD |
68 | static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, |
69 | unsigned long old_addr, unsigned long old_end, | |
70 | struct vm_area_struct *new_vma, pmd_t *new_pmd, | |
71 | unsigned long new_addr) | |
1da177e4 LT |
72 | { |
73 | struct address_space *mapping = NULL; | |
74 | struct mm_struct *mm = vma->vm_mm; | |
7be7a546 | 75 | pte_t *old_pte, *new_pte, pte; |
4c21e2f2 | 76 | spinlock_t *old_ptl, *new_ptl; |
1da177e4 LT |
77 | |
78 | if (vma->vm_file) { | |
79 | /* | |
80 | * Subtle point from Rajesh Venkatasubramanian: before | |
81 | * moving file-based ptes, we must lock vmtruncate out, | |
82 | * since it might clean the dst vma before the src vma, | |
83 | * and we propagate stale pages into the dst afterward. | |
84 | */ | |
85 | mapping = vma->vm_file->f_mapping; | |
86 | spin_lock(&mapping->i_mmap_lock); | |
87 | if (new_vma->vm_truncate_count && | |
88 | new_vma->vm_truncate_count != vma->vm_truncate_count) | |
89 | new_vma->vm_truncate_count = 0; | |
90 | } | |
1da177e4 | 91 | |
4c21e2f2 HD |
92 | /* |
93 | * We don't have to worry about the ordering of src and dst | |
94 | * pte locks because exclusive mmap_sem prevents deadlock. | |
95 | */ | |
c74df32c HD |
96 | old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); |
97 | new_pte = pte_offset_map_nested(new_pmd, new_addr); | |
4c21e2f2 HD |
98 | new_ptl = pte_lockptr(mm, new_pmd); |
99 | if (new_ptl != old_ptl) | |
f20dc5f7 | 100 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); |
7be7a546 HD |
101 | |
102 | for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, | |
103 | new_pte++, new_addr += PAGE_SIZE) { | |
104 | if (pte_none(*old_pte)) | |
105 | continue; | |
106 | pte = ptep_clear_flush(vma, old_addr, old_pte); | |
107 | /* ZERO_PAGE can be dependant on virtual addr */ | |
108 | pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); | |
109 | set_pte_at(mm, new_addr, new_pte, pte); | |
1da177e4 | 110 | } |
7be7a546 | 111 | |
4c21e2f2 HD |
112 | if (new_ptl != old_ptl) |
113 | spin_unlock(new_ptl); | |
7be7a546 | 114 | pte_unmap_nested(new_pte - 1); |
c74df32c | 115 | pte_unmap_unlock(old_pte - 1, old_ptl); |
1da177e4 LT |
116 | if (mapping) |
117 | spin_unlock(&mapping->i_mmap_lock); | |
1da177e4 LT |
118 | } |
119 | ||
7be7a546 HD |
120 | #define LATENCY_LIMIT (64 * PAGE_SIZE) |
121 | ||
1da177e4 LT |
122 | static unsigned long move_page_tables(struct vm_area_struct *vma, |
123 | unsigned long old_addr, struct vm_area_struct *new_vma, | |
124 | unsigned long new_addr, unsigned long len) | |
125 | { | |
7be7a546 HD |
126 | unsigned long extent, next, old_end; |
127 | pmd_t *old_pmd, *new_pmd; | |
1da177e4 | 128 | |
7be7a546 HD |
129 | old_end = old_addr + len; |
130 | flush_cache_range(vma, old_addr, old_end); | |
1da177e4 | 131 | |
7be7a546 | 132 | for (; old_addr < old_end; old_addr += extent, new_addr += extent) { |
1da177e4 | 133 | cond_resched(); |
7be7a546 HD |
134 | next = (old_addr + PMD_SIZE) & PMD_MASK; |
135 | if (next - 1 > old_end) | |
136 | next = old_end; | |
137 | extent = next - old_addr; | |
138 | old_pmd = get_old_pmd(vma->vm_mm, old_addr); | |
139 | if (!old_pmd) | |
140 | continue; | |
141 | new_pmd = alloc_new_pmd(vma->vm_mm, new_addr); | |
142 | if (!new_pmd) | |
143 | break; | |
144 | next = (new_addr + PMD_SIZE) & PMD_MASK; | |
145 | if (extent > next - new_addr) | |
146 | extent = next - new_addr; | |
147 | if (extent > LATENCY_LIMIT) | |
148 | extent = LATENCY_LIMIT; | |
149 | move_ptes(vma, old_pmd, old_addr, old_addr + extent, | |
150 | new_vma, new_pmd, new_addr); | |
1da177e4 | 151 | } |
7be7a546 HD |
152 | |
153 | return len + old_addr - old_end; /* how much done */ | |
1da177e4 LT |
154 | } |
155 | ||
156 | static unsigned long move_vma(struct vm_area_struct *vma, | |
157 | unsigned long old_addr, unsigned long old_len, | |
158 | unsigned long new_len, unsigned long new_addr) | |
159 | { | |
160 | struct mm_struct *mm = vma->vm_mm; | |
161 | struct vm_area_struct *new_vma; | |
162 | unsigned long vm_flags = vma->vm_flags; | |
163 | unsigned long new_pgoff; | |
164 | unsigned long moved_len; | |
165 | unsigned long excess = 0; | |
365e9c87 | 166 | unsigned long hiwater_vm; |
1da177e4 LT |
167 | int split = 0; |
168 | ||
169 | /* | |
170 | * We'd prefer to avoid failure later on in do_munmap: | |
171 | * which may split one vma into three before unmapping. | |
172 | */ | |
173 | if (mm->map_count >= sysctl_max_map_count - 3) | |
174 | return -ENOMEM; | |
175 | ||
176 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); | |
177 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); | |
178 | if (!new_vma) | |
179 | return -ENOMEM; | |
180 | ||
181 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); | |
182 | if (moved_len < old_len) { | |
183 | /* | |
184 | * On error, move entries back from new area to old, | |
185 | * which will succeed since page tables still there, | |
186 | * and then proceed to unmap new area instead of old. | |
187 | */ | |
188 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); | |
189 | vma = new_vma; | |
190 | old_len = new_len; | |
191 | old_addr = new_addr; | |
192 | new_addr = -ENOMEM; | |
193 | } | |
194 | ||
195 | /* Conceal VM_ACCOUNT so old reservation is not undone */ | |
196 | if (vm_flags & VM_ACCOUNT) { | |
197 | vma->vm_flags &= ~VM_ACCOUNT; | |
198 | excess = vma->vm_end - vma->vm_start - old_len; | |
199 | if (old_addr > vma->vm_start && | |
200 | old_addr + old_len < vma->vm_end) | |
201 | split = 1; | |
202 | } | |
203 | ||
71799062 | 204 | /* |
365e9c87 HD |
205 | * If we failed to move page tables we still do total_vm increment |
206 | * since do_munmap() will decrement it by old_len == new_len. | |
207 | * | |
208 | * Since total_vm is about to be raised artificially high for a | |
209 | * moment, we need to restore high watermark afterwards: if stats | |
210 | * are taken meanwhile, total_vm and hiwater_vm appear too high. | |
211 | * If this were a serious issue, we'd add a flag to do_munmap(). | |
71799062 | 212 | */ |
365e9c87 | 213 | hiwater_vm = mm->hiwater_vm; |
71799062 | 214 | mm->total_vm += new_len >> PAGE_SHIFT; |
ab50b8ed | 215 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
71799062 | 216 | |
1da177e4 LT |
217 | if (do_munmap(mm, old_addr, old_len) < 0) { |
218 | /* OOM: unable to split vma, just get accounts right */ | |
219 | vm_unacct_memory(excess >> PAGE_SHIFT); | |
220 | excess = 0; | |
221 | } | |
365e9c87 | 222 | mm->hiwater_vm = hiwater_vm; |
1da177e4 LT |
223 | |
224 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ | |
225 | if (excess) { | |
226 | vma->vm_flags |= VM_ACCOUNT; | |
227 | if (split) | |
228 | vma->vm_next->vm_flags |= VM_ACCOUNT; | |
229 | } | |
230 | ||
1da177e4 LT |
231 | if (vm_flags & VM_LOCKED) { |
232 | mm->locked_vm += new_len >> PAGE_SHIFT; | |
233 | if (new_len > old_len) | |
234 | make_pages_present(new_addr + old_len, | |
235 | new_addr + new_len); | |
236 | } | |
237 | ||
238 | return new_addr; | |
239 | } | |
240 | ||
241 | /* | |
242 | * Expand (or shrink) an existing mapping, potentially moving it at the | |
243 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) | |
244 | * | |
245 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise | |
246 | * This option implies MREMAP_MAYMOVE. | |
247 | */ | |
248 | unsigned long do_mremap(unsigned long addr, | |
249 | unsigned long old_len, unsigned long new_len, | |
250 | unsigned long flags, unsigned long new_addr) | |
251 | { | |
d0de32d9 | 252 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
253 | struct vm_area_struct *vma; |
254 | unsigned long ret = -EINVAL; | |
255 | unsigned long charged = 0; | |
256 | ||
257 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) | |
258 | goto out; | |
259 | ||
260 | if (addr & ~PAGE_MASK) | |
261 | goto out; | |
262 | ||
263 | old_len = PAGE_ALIGN(old_len); | |
264 | new_len = PAGE_ALIGN(new_len); | |
265 | ||
266 | /* | |
267 | * We allow a zero old-len as a special case | |
268 | * for DOS-emu "duplicate shm area" thing. But | |
269 | * a zero new-len is nonsensical. | |
270 | */ | |
271 | if (!new_len) | |
272 | goto out; | |
273 | ||
274 | /* new_addr is only valid if MREMAP_FIXED is specified */ | |
275 | if (flags & MREMAP_FIXED) { | |
276 | if (new_addr & ~PAGE_MASK) | |
277 | goto out; | |
278 | if (!(flags & MREMAP_MAYMOVE)) | |
279 | goto out; | |
280 | ||
281 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) | |
282 | goto out; | |
283 | ||
284 | /* Check if the location we're moving into overlaps the | |
285 | * old location at all, and fail if it does. | |
286 | */ | |
287 | if ((new_addr <= addr) && (new_addr+new_len) > addr) | |
288 | goto out; | |
289 | ||
290 | if ((addr <= new_addr) && (addr+old_len) > new_addr) | |
291 | goto out; | |
292 | ||
d0de32d9 | 293 | ret = do_munmap(mm, new_addr, new_len); |
1da177e4 LT |
294 | if (ret) |
295 | goto out; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Always allow a shrinking remap: that just unmaps | |
300 | * the unnecessary pages.. | |
301 | * do_munmap does all the needed commit accounting | |
302 | */ | |
303 | if (old_len >= new_len) { | |
d0de32d9 | 304 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
1da177e4 LT |
305 | if (ret && old_len != new_len) |
306 | goto out; | |
307 | ret = addr; | |
308 | if (!(flags & MREMAP_FIXED) || (new_addr == addr)) | |
309 | goto out; | |
310 | old_len = new_len; | |
311 | } | |
312 | ||
313 | /* | |
314 | * Ok, we need to grow.. or relocate. | |
315 | */ | |
316 | ret = -EFAULT; | |
d0de32d9 | 317 | vma = find_vma(mm, addr); |
1da177e4 LT |
318 | if (!vma || vma->vm_start > addr) |
319 | goto out; | |
320 | if (is_vm_hugetlb_page(vma)) { | |
321 | ret = -EINVAL; | |
322 | goto out; | |
323 | } | |
324 | /* We can't remap across vm area boundaries */ | |
325 | if (old_len > vma->vm_end - addr) | |
326 | goto out; | |
4d7672b4 | 327 | if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { |
1da177e4 LT |
328 | if (new_len > old_len) |
329 | goto out; | |
330 | } | |
331 | if (vma->vm_flags & VM_LOCKED) { | |
332 | unsigned long locked, lock_limit; | |
d0de32d9 | 333 | locked = mm->locked_vm << PAGE_SHIFT; |
1da177e4 LT |
334 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
335 | locked += new_len - old_len; | |
336 | ret = -EAGAIN; | |
337 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
338 | goto out; | |
339 | } | |
d0de32d9 | 340 | if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) { |
119f657c | 341 | ret = -ENOMEM; |
1da177e4 | 342 | goto out; |
119f657c | 343 | } |
1da177e4 LT |
344 | |
345 | if (vma->vm_flags & VM_ACCOUNT) { | |
346 | charged = (new_len - old_len) >> PAGE_SHIFT; | |
347 | if (security_vm_enough_memory(charged)) | |
348 | goto out_nc; | |
349 | } | |
350 | ||
351 | /* old_len exactly to the end of the area.. | |
352 | * And we're not relocating the area. | |
353 | */ | |
354 | if (old_len == vma->vm_end - addr && | |
355 | !((flags & MREMAP_FIXED) && (addr != new_addr)) && | |
356 | (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { | |
357 | unsigned long max_addr = TASK_SIZE; | |
358 | if (vma->vm_next) | |
359 | max_addr = vma->vm_next->vm_start; | |
360 | /* can we just expand the current mapping? */ | |
361 | if (max_addr - addr >= new_len) { | |
362 | int pages = (new_len - old_len) >> PAGE_SHIFT; | |
363 | ||
364 | vma_adjust(vma, vma->vm_start, | |
365 | addr + new_len, vma->vm_pgoff, NULL); | |
366 | ||
d0de32d9 HD |
367 | mm->total_vm += pages; |
368 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); | |
1da177e4 | 369 | if (vma->vm_flags & VM_LOCKED) { |
d0de32d9 | 370 | mm->locked_vm += pages; |
1da177e4 LT |
371 | make_pages_present(addr + old_len, |
372 | addr + new_len); | |
373 | } | |
374 | ret = addr; | |
375 | goto out; | |
376 | } | |
377 | } | |
378 | ||
379 | /* | |
380 | * We weren't able to just expand or shrink the area, | |
381 | * we need to create a new one and move it.. | |
382 | */ | |
383 | ret = -ENOMEM; | |
384 | if (flags & MREMAP_MAYMOVE) { | |
385 | if (!(flags & MREMAP_FIXED)) { | |
386 | unsigned long map_flags = 0; | |
387 | if (vma->vm_flags & VM_MAYSHARE) | |
388 | map_flags |= MAP_SHARED; | |
389 | ||
390 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, | |
391 | vma->vm_pgoff, map_flags); | |
392 | ret = new_addr; | |
393 | if (new_addr & ~PAGE_MASK) | |
394 | goto out; | |
395 | } | |
396 | ret = move_vma(vma, addr, old_len, new_len, new_addr); | |
397 | } | |
398 | out: | |
399 | if (ret & ~PAGE_MASK) | |
400 | vm_unacct_memory(charged); | |
401 | out_nc: | |
402 | return ret; | |
403 | } | |
404 | ||
405 | asmlinkage unsigned long sys_mremap(unsigned long addr, | |
406 | unsigned long old_len, unsigned long new_len, | |
407 | unsigned long flags, unsigned long new_addr) | |
408 | { | |
409 | unsigned long ret; | |
410 | ||
411 | down_write(¤t->mm->mmap_sem); | |
412 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); | |
413 | up_write(¤t->mm->mmap_sem); | |
414 | return ret; | |
415 | } |