4 * (C) Copyright 1996 Linus Torvalds
6 * Address space accounting code <alan@redhat.com>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
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>
17 #include <linux/highmem.h>
18 #include <linux/security.h>
20 #include <asm/uaccess.h>
21 #include <asm/pgalloc.h>
22 #include <asm/cacheflush.h>
23 #include <asm/tlbflush.h>
25 static pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr)
31 pgd = pgd_offset(mm, addr);
40 pmd = pmd_offset(pgd, addr);
49 pte = pte_offset_map_nested(pmd, addr);
51 pte_unmap_nested(pte);
58 static inline int page_table_present(struct mm_struct *mm, unsigned long addr)
63 pgd = pgd_offset(mm, addr);
66 pmd = pmd_offset(pgd, addr);
67 return pmd_present(*pmd);
70 static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr)
75 pmd = pmd_alloc(mm, pgd_offset(mm, addr), addr);
77 pte = pte_alloc_map(mm, pmd, addr);
82 copy_one_pte(struct vm_area_struct *vma, unsigned long old_addr,
83 pte_t *src, pte_t *dst)
87 struct page *page = NULL;
89 if (pte_present(*src))
90 page = pte_page(*src);
92 if (!pte_none(*src)) {
93 pte = ptep_clear_flush(vma, old_addr, src);
95 /* No dest? We must put it back. */
105 move_one_page(struct vm_area_struct *vma, unsigned long old_addr,
106 unsigned long new_addr)
108 struct mm_struct *mm = vma->vm_mm;
112 spin_lock(&mm->page_table_lock);
113 src = get_one_pte_map_nested(mm, old_addr);
116 * Look to see whether alloc_one_pte_map needs to perform a
117 * memory allocation. If it does then we need to drop the
120 if (!page_table_present(mm, new_addr)) {
121 pte_unmap_nested(src);
124 dst = alloc_one_pte_map(mm, new_addr);
126 src = get_one_pte_map_nested(mm, old_addr);
128 * Since alloc_one_pte_map can drop and re-acquire
129 * page_table_lock, we should re-check the src entry...
132 error = copy_one_pte(vma, old_addr, src, dst);
133 pte_unmap_nested(src);
137 spin_unlock(&mm->page_table_lock);
141 static int move_page_tables(struct vm_area_struct *vma,
142 unsigned long new_addr, unsigned long old_addr, unsigned long len)
144 unsigned long offset = len;
146 flush_cache_range(vma, old_addr, old_addr + len);
149 * This is not the clever way to do this, but we're taking the
150 * easy way out on the assumption that most remappings will be
151 * only a few pages.. This also makes error recovery easier.
155 if (move_one_page(vma, old_addr + offset, new_addr + offset))
161 * Ok, the move failed because we didn't have enough pages for
162 * the new page table tree. This is unlikely, but we have to
163 * take the possibility into account. In that case we just move
164 * all the pages back (this will work, because we still have
165 * the old page tables)
168 flush_cache_range(vma, new_addr, new_addr + len);
169 while ((offset += PAGE_SIZE) < len)
170 move_one_page(vma, new_addr + offset, old_addr + offset);
171 zap_page_range(vma, new_addr, len);
175 static unsigned long move_vma(struct vm_area_struct *vma,
176 unsigned long addr, unsigned long old_len, unsigned long new_len,
177 unsigned long new_addr)
179 #if VMA_MERGING_FIXUP
180 struct mm_struct *mm = vma->vm_mm;
181 struct vm_area_struct *new_vma, *next, *prev;
183 struct vm_area_struct *new_vma;
189 #if VMA_MERGING_FIXUP
190 next = find_vma_prev(mm, new_addr, &prev);
192 if (prev && prev->vm_end == new_addr &&
193 can_vma_merge(prev, vma->vm_flags) && !vma->vm_file &&
194 !(vma->vm_flags & VM_SHARED)) {
195 spin_lock(&mm->page_table_lock);
196 prev->vm_end = new_addr + new_len;
197 spin_unlock(&mm->page_table_lock);
199 if (next != prev->vm_next)
201 if (prev->vm_end == next->vm_start &&
202 can_vma_merge(next, prev->vm_flags)) {
203 spin_lock(&mm->page_table_lock);
204 prev->vm_end = next->vm_end;
205 __vma_unlink(mm, next, prev);
206 spin_unlock(&mm->page_table_lock);
210 kmem_cache_free(vm_area_cachep, next);
212 } else if (next->vm_start == new_addr + new_len &&
213 can_vma_merge(next, vma->vm_flags) &&
214 !vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
215 spin_lock(&mm->page_table_lock);
216 next->vm_start = new_addr;
217 spin_unlock(&mm->page_table_lock);
221 prev = find_vma(mm, new_addr-1);
222 if (prev && prev->vm_end == new_addr &&
223 can_vma_merge(prev, vma->vm_flags) && !vma->vm_file &&
224 !(vma->vm_flags & VM_SHARED)) {
225 spin_lock(&mm->page_table_lock);
226 prev->vm_end = new_addr + new_len;
227 spin_unlock(&mm->page_table_lock);
235 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
241 if (!move_page_tables(vma, new_addr, addr, old_len)) {
242 unsigned long vm_locked = vma->vm_flags & VM_LOCKED;
246 INIT_VMA_SHARED(new_vma);
247 new_vma->vm_start = new_addr;
248 new_vma->vm_end = new_addr+new_len;
249 new_vma->vm_pgoff += (addr-vma->vm_start) >> PAGE_SHIFT;
250 if (new_vma->vm_file)
251 get_file(new_vma->vm_file);
252 if (new_vma->vm_ops && new_vma->vm_ops->open)
253 new_vma->vm_ops->open(new_vma);
254 insert_vm_struct(current->mm, new_vma);
257 /* Conceal VM_ACCOUNT so old reservation is not undone */
258 if (vma->vm_flags & VM_ACCOUNT) {
259 vma->vm_flags &= ~VM_ACCOUNT;
260 if (addr > vma->vm_start) {
261 if (addr + old_len < vma->vm_end)
263 } else if (addr + old_len == vma->vm_end)
264 vma = NULL; /* it will be removed */
266 vma = NULL; /* nothing more to do */
268 do_munmap(current->mm, addr, old_len);
270 /* Restore VM_ACCOUNT if one or two pieces of vma left */
272 vma->vm_flags |= VM_ACCOUNT;
274 vma->vm_next->vm_flags |= VM_ACCOUNT;
277 current->mm->total_vm += new_len >> PAGE_SHIFT;
279 current->mm->locked_vm += new_len >> PAGE_SHIFT;
280 if (new_len > old_len)
281 make_pages_present(new_addr + old_len,
287 kmem_cache_free(vm_area_cachep, new_vma);
293 * Expand (or shrink) an existing mapping, potentially moving it at the
294 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
296 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
297 * This option implies MREMAP_MAYMOVE.
299 unsigned long do_mremap(unsigned long addr,
300 unsigned long old_len, unsigned long new_len,
301 unsigned long flags, unsigned long new_addr)
303 struct vm_area_struct *vma;
304 struct address_space *mapping = NULL;
305 struct prio_tree_root *root = NULL;
306 unsigned long ret = -EINVAL;
307 unsigned long charged = 0;
309 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
312 if (addr & ~PAGE_MASK)
315 old_len = PAGE_ALIGN(old_len);
316 new_len = PAGE_ALIGN(new_len);
319 * We allow a zero old-len as a special case
320 * for DOS-emu "duplicate shm area" thing. But
321 * a zero new-len is nonsensical.
326 /* new_addr is only valid if MREMAP_FIXED is specified */
327 if (flags & MREMAP_FIXED) {
328 if (new_addr & ~PAGE_MASK)
330 if (!(flags & MREMAP_MAYMOVE))
333 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
336 /* Check if the location we're moving into overlaps the
337 * old location at all, and fail if it does.
339 if ((new_addr <= addr) && (new_addr+new_len) > addr)
342 if ((addr <= new_addr) && (addr+old_len) > new_addr)
345 ret = do_munmap(current->mm, new_addr, new_len);
351 * Always allow a shrinking remap: that just unmaps
352 * the unnecessary pages..
353 * do_munmap does all the needed commit accounting
355 if (old_len >= new_len) {
356 ret = do_munmap(current->mm, addr+new_len, old_len - new_len);
357 if (ret && old_len != new_len)
360 if (!(flags & MREMAP_FIXED) || (new_addr == addr))
366 * Ok, we need to grow.. or relocate.
369 vma = find_vma(current->mm, addr);
370 if (!vma || vma->vm_start > addr)
372 if (is_vm_hugetlb_page(vma)) {
376 /* We can't remap across vm area boundaries */
377 if (old_len > vma->vm_end - addr)
379 if (vma->vm_flags & VM_DONTEXPAND) {
380 if (new_len > old_len)
383 if (vma->vm_flags & VM_LOCKED) {
384 unsigned long locked = current->mm->locked_vm << PAGE_SHIFT;
385 locked += new_len - old_len;
387 if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
391 if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
392 > current->rlim[RLIMIT_AS].rlim_cur)
395 if (vma->vm_flags & VM_ACCOUNT) {
396 charged = (new_len - old_len) >> PAGE_SHIFT;
397 if (security_vm_enough_memory(charged))
401 /* old_len exactly to the end of the area..
402 * And we're not relocating the area.
404 if (old_len == vma->vm_end - addr &&
405 !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
406 (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
407 unsigned long max_addr = TASK_SIZE;
409 max_addr = vma->vm_next->vm_start;
410 /* can we just expand the current mapping? */
411 if (max_addr - addr >= new_len) {
412 int pages = (new_len - old_len) >> PAGE_SHIFT;
415 mapping = vma->vm_file->f_mapping;
416 if (vma->vm_flags & VM_SHARED) {
417 if (likely(!(vma->vm_flags & VM_NONLINEAR)))
418 root = &mapping->i_mmap_shared;
421 root = &mapping->i_mmap;
422 down(&mapping->i_shared_sem);
425 spin_lock(&vma->vm_mm->page_table_lock);
426 __vma_modify(root, vma, vma->vm_start,
427 addr + new_len, vma->vm_pgoff);
428 spin_unlock(&vma->vm_mm->page_table_lock);
431 up(&mapping->i_shared_sem);
433 current->mm->total_vm += pages;
434 if (vma->vm_flags & VM_LOCKED) {
435 current->mm->locked_vm += pages;
436 make_pages_present(addr + old_len,
445 * We weren't able to just expand or shrink the area,
446 * we need to create a new one and move it..
449 if (flags & MREMAP_MAYMOVE) {
450 if (!(flags & MREMAP_FIXED)) {
451 unsigned long map_flags = 0;
452 if (vma->vm_flags & VM_MAYSHARE)
453 map_flags |= MAP_SHARED;
455 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
456 vma->vm_pgoff, map_flags);
458 if (new_addr & ~PAGE_MASK)
461 ret = move_vma(vma, addr, old_len, new_len, new_addr);
464 if (ret & ~PAGE_MASK)
465 vm_unacct_memory(charged);
470 asmlinkage unsigned long sys_mremap(unsigned long addr,
471 unsigned long old_len, unsigned long new_len,
472 unsigned long flags, unsigned long new_addr)
476 down_write(¤t->mm->mmap_sem);
477 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
478 up_write(¤t->mm->mmap_sem);