staging: IIO: DAC: Add support for the AD5543/AD5553
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / mremap.c
blob9925b6391b8035a547355a8ad9919e9a8f06f920
1 /*
2 * mm/mremap.c
4 * (C) Copyright 1996 Linus Torvalds
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
10 #include <linux/mm.h>
11 #include <linux/hugetlb.h>
12 #include <linux/shm.h>
13 #include <linux/ksm.h>
14 #include <linux/mman.h>
15 #include <linux/swap.h>
16 #include <linux/capability.h>
17 #include <linux/fs.h>
18 #include <linux/highmem.h>
19 #include <linux/security.h>
20 #include <linux/syscalls.h>
21 #include <linux/mmu_notifier.h>
23 #include <asm/uaccess.h>
24 #include <asm/cacheflush.h>
25 #include <asm/tlbflush.h>
27 #include "internal.h"
29 static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
31 pgd_t *pgd;
32 pud_t *pud;
33 pmd_t *pmd;
35 pgd = pgd_offset(mm, addr);
36 if (pgd_none_or_clear_bad(pgd))
37 return NULL;
39 pud = pud_offset(pgd, addr);
40 if (pud_none_or_clear_bad(pud))
41 return NULL;
43 pmd = pmd_offset(pud, addr);
44 split_huge_page_pmd(mm, pmd);
45 if (pmd_none_or_clear_bad(pmd))
46 return NULL;
48 return pmd;
51 static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
52 unsigned long addr)
54 pgd_t *pgd;
55 pud_t *pud;
56 pmd_t *pmd;
58 pgd = pgd_offset(mm, addr);
59 pud = pud_alloc(mm, pgd, addr);
60 if (!pud)
61 return NULL;
63 pmd = pmd_alloc(mm, pud, addr);
64 if (!pmd)
65 return NULL;
67 VM_BUG_ON(pmd_trans_huge(*pmd));
68 if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
69 return NULL;
71 return pmd;
74 static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
75 unsigned long old_addr, unsigned long old_end,
76 struct vm_area_struct *new_vma, pmd_t *new_pmd,
77 unsigned long new_addr)
79 struct address_space *mapping = NULL;
80 struct mm_struct *mm = vma->vm_mm;
81 pte_t *old_pte, *new_pte, pte;
82 spinlock_t *old_ptl, *new_ptl;
83 unsigned long old_start;
85 old_start = old_addr;
86 mmu_notifier_invalidate_range_start(vma->vm_mm,
87 old_start, old_end);
88 if (vma->vm_file) {
90 * Subtle point from Rajesh Venkatasubramanian: before
91 * moving file-based ptes, we must lock truncate_pagecache
92 * out, since it might clean the dst vma before the src vma,
93 * and we propagate stale pages into the dst afterward.
95 mapping = vma->vm_file->f_mapping;
96 spin_lock(&mapping->i_mmap_lock);
97 if (new_vma->vm_truncate_count &&
98 new_vma->vm_truncate_count != vma->vm_truncate_count)
99 new_vma->vm_truncate_count = 0;
103 * We don't have to worry about the ordering of src and dst
104 * pte locks because exclusive mmap_sem prevents deadlock.
106 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
107 new_pte = pte_offset_map(new_pmd, new_addr);
108 new_ptl = pte_lockptr(mm, new_pmd);
109 if (new_ptl != old_ptl)
110 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
111 arch_enter_lazy_mmu_mode();
113 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
114 new_pte++, new_addr += PAGE_SIZE) {
115 if (pte_none(*old_pte))
116 continue;
117 pte = ptep_clear_flush(vma, old_addr, old_pte);
118 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
119 set_pte_at(mm, new_addr, new_pte, pte);
122 arch_leave_lazy_mmu_mode();
123 if (new_ptl != old_ptl)
124 spin_unlock(new_ptl);
125 pte_unmap(new_pte - 1);
126 pte_unmap_unlock(old_pte - 1, old_ptl);
127 if (mapping)
128 spin_unlock(&mapping->i_mmap_lock);
129 mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
132 #define LATENCY_LIMIT (64 * PAGE_SIZE)
134 unsigned long move_page_tables(struct vm_area_struct *vma,
135 unsigned long old_addr, struct vm_area_struct *new_vma,
136 unsigned long new_addr, unsigned long len)
138 unsigned long extent, next, old_end;
139 pmd_t *old_pmd, *new_pmd;
141 old_end = old_addr + len;
142 flush_cache_range(vma, old_addr, old_end);
144 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
145 cond_resched();
146 next = (old_addr + PMD_SIZE) & PMD_MASK;
147 if (next - 1 > old_end)
148 next = old_end;
149 extent = next - old_addr;
150 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
151 if (!old_pmd)
152 continue;
153 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
154 if (!new_pmd)
155 break;
156 next = (new_addr + PMD_SIZE) & PMD_MASK;
157 if (extent > next - new_addr)
158 extent = next - new_addr;
159 if (extent > LATENCY_LIMIT)
160 extent = LATENCY_LIMIT;
161 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
162 new_vma, new_pmd, new_addr);
165 return len + old_addr - old_end; /* how much done */
168 static unsigned long move_vma(struct vm_area_struct *vma,
169 unsigned long old_addr, unsigned long old_len,
170 unsigned long new_len, unsigned long new_addr)
172 struct mm_struct *mm = vma->vm_mm;
173 struct vm_area_struct *new_vma;
174 unsigned long vm_flags = vma->vm_flags;
175 unsigned long new_pgoff;
176 unsigned long moved_len;
177 unsigned long excess = 0;
178 unsigned long hiwater_vm;
179 int split = 0;
180 int err;
183 * We'd prefer to avoid failure later on in do_munmap:
184 * which may split one vma into three before unmapping.
186 if (mm->map_count >= sysctl_max_map_count - 3)
187 return -ENOMEM;
190 * Advise KSM to break any KSM pages in the area to be moved:
191 * it would be confusing if they were to turn up at the new
192 * location, where they happen to coincide with different KSM
193 * pages recently unmapped. But leave vma->vm_flags as it was,
194 * so KSM can come around to merge on vma and new_vma afterwards.
196 err = ksm_madvise(vma, old_addr, old_addr + old_len,
197 MADV_UNMERGEABLE, &vm_flags);
198 if (err)
199 return err;
201 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
202 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
203 if (!new_vma)
204 return -ENOMEM;
206 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
207 if (moved_len < old_len) {
209 * On error, move entries back from new area to old,
210 * which will succeed since page tables still there,
211 * and then proceed to unmap new area instead of old.
213 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
214 vma = new_vma;
215 old_len = new_len;
216 old_addr = new_addr;
217 new_addr = -ENOMEM;
220 /* Conceal VM_ACCOUNT so old reservation is not undone */
221 if (vm_flags & VM_ACCOUNT) {
222 vma->vm_flags &= ~VM_ACCOUNT;
223 excess = vma->vm_end - vma->vm_start - old_len;
224 if (old_addr > vma->vm_start &&
225 old_addr + old_len < vma->vm_end)
226 split = 1;
230 * If we failed to move page tables we still do total_vm increment
231 * since do_munmap() will decrement it by old_len == new_len.
233 * Since total_vm is about to be raised artificially high for a
234 * moment, we need to restore high watermark afterwards: if stats
235 * are taken meanwhile, total_vm and hiwater_vm appear too high.
236 * If this were a serious issue, we'd add a flag to do_munmap().
238 hiwater_vm = mm->hiwater_vm;
239 mm->total_vm += new_len >> PAGE_SHIFT;
240 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
242 if (do_munmap(mm, old_addr, old_len) < 0) {
243 /* OOM: unable to split vma, just get accounts right */
244 vm_unacct_memory(excess >> PAGE_SHIFT);
245 excess = 0;
247 mm->hiwater_vm = hiwater_vm;
249 /* Restore VM_ACCOUNT if one or two pieces of vma left */
250 if (excess) {
251 vma->vm_flags |= VM_ACCOUNT;
252 if (split)
253 vma->vm_next->vm_flags |= VM_ACCOUNT;
256 if (vm_flags & VM_LOCKED) {
257 mm->locked_vm += new_len >> PAGE_SHIFT;
258 if (new_len > old_len)
259 mlock_vma_pages_range(new_vma, new_addr + old_len,
260 new_addr + new_len);
263 return new_addr;
266 static struct vm_area_struct *vma_to_resize(unsigned long addr,
267 unsigned long old_len, unsigned long new_len, unsigned long *p)
269 struct mm_struct *mm = current->mm;
270 struct vm_area_struct *vma = find_vma(mm, addr);
272 if (!vma || vma->vm_start > addr)
273 goto Efault;
275 if (is_vm_hugetlb_page(vma))
276 goto Einval;
278 /* We can't remap across vm area boundaries */
279 if (old_len > vma->vm_end - addr)
280 goto Efault;
282 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
283 if (new_len > old_len)
284 goto Efault;
287 if (vma->vm_flags & VM_LOCKED) {
288 unsigned long locked, lock_limit;
289 locked = mm->locked_vm << PAGE_SHIFT;
290 lock_limit = rlimit(RLIMIT_MEMLOCK);
291 locked += new_len - old_len;
292 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
293 goto Eagain;
296 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
297 goto Enomem;
299 if (vma->vm_flags & VM_ACCOUNT) {
300 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
301 if (security_vm_enough_memory(charged))
302 goto Efault;
303 *p = charged;
306 return vma;
308 Efault: /* very odd choice for most of the cases, but... */
309 return ERR_PTR(-EFAULT);
310 Einval:
311 return ERR_PTR(-EINVAL);
312 Enomem:
313 return ERR_PTR(-ENOMEM);
314 Eagain:
315 return ERR_PTR(-EAGAIN);
318 static unsigned long mremap_to(unsigned long addr,
319 unsigned long old_len, unsigned long new_addr,
320 unsigned long new_len)
322 struct mm_struct *mm = current->mm;
323 struct vm_area_struct *vma;
324 unsigned long ret = -EINVAL;
325 unsigned long charged = 0;
326 unsigned long map_flags;
328 if (new_addr & ~PAGE_MASK)
329 goto out;
331 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
332 goto out;
334 /* Check if the location we're moving into overlaps the
335 * old location at all, and fail if it does.
337 if ((new_addr <= addr) && (new_addr+new_len) > addr)
338 goto out;
340 if ((addr <= new_addr) && (addr+old_len) > new_addr)
341 goto out;
343 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
344 if (ret)
345 goto out;
347 ret = do_munmap(mm, new_addr, new_len);
348 if (ret)
349 goto out;
351 if (old_len >= new_len) {
352 ret = do_munmap(mm, addr+new_len, old_len - new_len);
353 if (ret && old_len != new_len)
354 goto out;
355 old_len = new_len;
358 vma = vma_to_resize(addr, old_len, new_len, &charged);
359 if (IS_ERR(vma)) {
360 ret = PTR_ERR(vma);
361 goto out;
364 map_flags = MAP_FIXED;
365 if (vma->vm_flags & VM_MAYSHARE)
366 map_flags |= MAP_SHARED;
368 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
369 ((addr - vma->vm_start) >> PAGE_SHIFT),
370 map_flags);
371 if (ret & ~PAGE_MASK)
372 goto out1;
374 ret = move_vma(vma, addr, old_len, new_len, new_addr);
375 if (!(ret & ~PAGE_MASK))
376 goto out;
377 out1:
378 vm_unacct_memory(charged);
380 out:
381 return ret;
384 static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
386 unsigned long end = vma->vm_end + delta;
387 if (end < vma->vm_end) /* overflow */
388 return 0;
389 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
390 return 0;
391 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
392 0, MAP_FIXED) & ~PAGE_MASK)
393 return 0;
394 return 1;
398 * Expand (or shrink) an existing mapping, potentially moving it at the
399 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
401 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
402 * This option implies MREMAP_MAYMOVE.
404 unsigned long do_mremap(unsigned long addr,
405 unsigned long old_len, unsigned long new_len,
406 unsigned long flags, unsigned long new_addr)
408 struct mm_struct *mm = current->mm;
409 struct vm_area_struct *vma;
410 unsigned long ret = -EINVAL;
411 unsigned long charged = 0;
413 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
414 goto out;
416 if (addr & ~PAGE_MASK)
417 goto out;
419 old_len = PAGE_ALIGN(old_len);
420 new_len = PAGE_ALIGN(new_len);
423 * We allow a zero old-len as a special case
424 * for DOS-emu "duplicate shm area" thing. But
425 * a zero new-len is nonsensical.
427 if (!new_len)
428 goto out;
430 if (flags & MREMAP_FIXED) {
431 if (flags & MREMAP_MAYMOVE)
432 ret = mremap_to(addr, old_len, new_addr, new_len);
433 goto out;
437 * Always allow a shrinking remap: that just unmaps
438 * the unnecessary pages..
439 * do_munmap does all the needed commit accounting
441 if (old_len >= new_len) {
442 ret = do_munmap(mm, addr+new_len, old_len - new_len);
443 if (ret && old_len != new_len)
444 goto out;
445 ret = addr;
446 goto out;
450 * Ok, we need to grow..
452 vma = vma_to_resize(addr, old_len, new_len, &charged);
453 if (IS_ERR(vma)) {
454 ret = PTR_ERR(vma);
455 goto out;
458 /* old_len exactly to the end of the area..
460 if (old_len == vma->vm_end - addr) {
461 /* can we just expand the current mapping? */
462 if (vma_expandable(vma, new_len - old_len)) {
463 int pages = (new_len - old_len) >> PAGE_SHIFT;
465 if (vma_adjust(vma, vma->vm_start, addr + new_len,
466 vma->vm_pgoff, NULL)) {
467 ret = -ENOMEM;
468 goto out;
471 mm->total_vm += pages;
472 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
473 if (vma->vm_flags & VM_LOCKED) {
474 mm->locked_vm += pages;
475 mlock_vma_pages_range(vma, addr + old_len,
476 addr + new_len);
478 ret = addr;
479 goto out;
484 * We weren't able to just expand or shrink the area,
485 * we need to create a new one and move it..
487 ret = -ENOMEM;
488 if (flags & MREMAP_MAYMOVE) {
489 unsigned long map_flags = 0;
490 if (vma->vm_flags & VM_MAYSHARE)
491 map_flags |= MAP_SHARED;
493 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
494 vma->vm_pgoff +
495 ((addr - vma->vm_start) >> PAGE_SHIFT),
496 map_flags);
497 if (new_addr & ~PAGE_MASK) {
498 ret = new_addr;
499 goto out;
502 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
503 if (ret)
504 goto out;
505 ret = move_vma(vma, addr, old_len, new_len, new_addr);
507 out:
508 if (ret & ~PAGE_MASK)
509 vm_unacct_memory(charged);
510 return ret;
513 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
514 unsigned long, new_len, unsigned long, flags,
515 unsigned long, new_addr)
517 unsigned long ret;
519 down_write(&current->mm->mmap_sem);
520 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
521 up_write(&current->mm->mmap_sem);
522 return ret;