blob: 2b16b00a5b115be2c13897aab5763562312ecb84 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/nommu.c
3 *
4 * Replacement code for mm functions to support CPU's that don't
5 * have any form of memory management unit (thus no virtual memory).
6 *
7 * See Documentation/nommu-mmap.txt
8 *
9 * Copyright (c) 2004-2005 David Howells <dhowells@redhat.com>
10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
13 */
14
15#include <linux/mm.h>
16#include <linux/mman.h>
17#include <linux/swap.h>
18#include <linux/file.h>
19#include <linux/highmem.h>
20#include <linux/pagemap.h>
21#include <linux/slab.h>
22#include <linux/vmalloc.h>
23#include <linux/ptrace.h>
24#include <linux/blkdev.h>
25#include <linux/backing-dev.h>
26#include <linux/mount.h>
27#include <linux/personality.h>
28#include <linux/security.h>
29#include <linux/syscalls.h>
30
31#include <asm/uaccess.h>
32#include <asm/tlb.h>
33#include <asm/tlbflush.h>
34
35void *high_memory;
36struct page *mem_map;
37unsigned long max_mapnr;
38unsigned long num_physpages;
39unsigned long askedalloc, realalloc;
40atomic_t vm_committed_space = ATOMIC_INIT(0);
41int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
42int sysctl_overcommit_ratio = 50; /* default is 50% */
43int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
44int heap_stack_gap = 0;
45
46EXPORT_SYMBOL(mem_map);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047EXPORT_SYMBOL(__vm_enough_memory);
Wu, Bryan6a04de62007-04-11 23:28:47 -070048EXPORT_SYMBOL(num_physpages);
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50/* list of shareable VMAs */
51struct rb_root nommu_vma_tree = RB_ROOT;
52DECLARE_RWSEM(nommu_vma_sem);
53
54struct vm_operations_struct generic_file_vm_ops = {
55};
56
Greg Ungerer66aa2b42005-09-12 11:18:10 +100057EXPORT_SYMBOL(vfree);
58EXPORT_SYMBOL(vmalloc_to_page);
59EXPORT_SYMBOL(vmalloc_32);
Luke Yang7a9166e2006-02-20 18:28:07 -080060EXPORT_SYMBOL(vmap);
61EXPORT_SYMBOL(vunmap);
Greg Ungerer66aa2b42005-09-12 11:18:10 +100062
Linus Torvalds1da177e2005-04-16 15:20:36 -070063/*
64 * Handle all mappings that got truncated by a "truncate()"
65 * system call.
66 *
67 * NOTE! We have to be ready to update the memory sharing
68 * between the file and the memory map for a potential last
69 * incomplete page. Ugly, but necessary.
70 */
71int vmtruncate(struct inode *inode, loff_t offset)
72{
73 struct address_space *mapping = inode->i_mapping;
74 unsigned long limit;
75
76 if (inode->i_size < offset)
77 goto do_expand;
78 i_size_write(inode, offset);
79
80 truncate_inode_pages(mapping, offset);
81 goto out_truncate;
82
83do_expand:
84 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
85 if (limit != RLIM_INFINITY && offset > limit)
86 goto out_sig;
87 if (offset > inode->i_sb->s_maxbytes)
88 goto out;
89 i_size_write(inode, offset);
90
91out_truncate:
92 if (inode->i_op && inode->i_op->truncate)
93 inode->i_op->truncate(inode);
94 return 0;
95out_sig:
96 send_sig(SIGXFSZ, current, 0);
97out:
98 return -EFBIG;
99}
100
101EXPORT_SYMBOL(vmtruncate);
102
103/*
104 * Return the total memory allocated for this pointer, not
105 * just what the caller asked for.
106 *
107 * Doesn't have to be accurate, i.e. may have races.
108 */
109unsigned int kobjsize(const void *objp)
110{
111 struct page *page;
112
113 if (!objp || !((page = virt_to_page(objp))))
114 return 0;
115
116 if (PageSlab(page))
117 return ksize(objp);
118
119 BUG_ON(page->index < 0);
120 BUG_ON(page->index >= MAX_ORDER);
121
122 return (PAGE_SIZE << page->index);
123}
124
125/*
David Howells7b4d5b82006-09-27 01:50:18 -0700126 * get a list of pages in an address range belonging to the specified process
127 * and indicate the VMA that covers each page
128 * - this is potentially dodgy as we may end incrementing the page count of a
129 * slab page or a secondary page from a compound page
130 * - don't permit access to VMAs that don't support it, such as I/O mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 */
132int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
133 unsigned long start, int len, int write, int force,
134 struct page **pages, struct vm_area_struct **vmas)
135{
Sonic Zhang910e46d2006-09-27 01:50:17 -0700136 struct vm_area_struct *vma;
David Howells7b4d5b82006-09-27 01:50:18 -0700137 unsigned long vm_flags;
138 int i;
139
140 /* calculate required read or write permissions.
141 * - if 'force' is set, we only require the "MAY" flags.
142 */
143 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
144 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
146 for (i = 0; i < len; i++) {
Sonic Zhang910e46d2006-09-27 01:50:17 -0700147 vma = find_vma(mm, start);
David Howells7b4d5b82006-09-27 01:50:18 -0700148 if (!vma)
149 goto finish_or_fault;
150
151 /* protect what we can, including chardevs */
152 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
153 !(vm_flags & vma->vm_flags))
154 goto finish_or_fault;
Sonic Zhang910e46d2006-09-27 01:50:17 -0700155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 if (pages) {
157 pages[i] = virt_to_page(start);
158 if (pages[i])
159 page_cache_get(pages[i]);
160 }
161 if (vmas)
Sonic Zhang910e46d2006-09-27 01:50:17 -0700162 vmas[i] = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 start += PAGE_SIZE;
164 }
David Howells7b4d5b82006-09-27 01:50:18 -0700165
166 return i;
167
168finish_or_fault:
169 return i ? : -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170}
171
Greg Ungerer66aa2b42005-09-12 11:18:10 +1000172EXPORT_SYMBOL(get_user_pages);
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174DEFINE_RWLOCK(vmlist_lock);
175struct vm_struct *vmlist;
176
177void vfree(void *addr)
178{
179 kfree(addr);
180}
181
Al Virodd0fc662005-10-07 07:46:04 +0100182void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183{
184 /*
185 * kmalloc doesn't like __GFP_HIGHMEM for some reason
186 */
Nick Piggin84097512006-03-22 00:08:34 -0800187 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188}
189
190struct page * vmalloc_to_page(void *addr)
191{
192 return virt_to_page(addr);
193}
194
195unsigned long vmalloc_to_pfn(void *addr)
196{
197 return page_to_pfn(virt_to_page(addr));
198}
199
200
201long vread(char *buf, char *addr, unsigned long count)
202{
203 memcpy(buf, addr, count);
204 return count;
205}
206
207long vwrite(char *buf, char *addr, unsigned long count)
208{
209 /* Don't allow overflow */
210 if ((unsigned long) addr + count < count)
211 count = -(unsigned long) addr;
212
213 memcpy(addr, buf, count);
214 return(count);
215}
216
217/*
218 * vmalloc - allocate virtually continguos memory
219 *
220 * @size: allocation size
221 *
222 * Allocate enough pages to cover @size from the page level
223 * allocator and map them into continguos kernel virtual space.
224 *
Michael Opdenackerc1c88972006-10-03 23:21:02 +0200225 * For tight control over page level allocator and protection flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 * use __vmalloc() instead.
227 */
228void *vmalloc(unsigned long size)
229{
230 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
231}
Andrew Mortonf6138882006-02-28 16:59:18 -0800232EXPORT_SYMBOL(vmalloc);
233
234void *vmalloc_node(unsigned long size, int node)
235{
236 return vmalloc(size);
237}
238EXPORT_SYMBOL(vmalloc_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
240/*
241 * vmalloc_32 - allocate virtually continguos memory (32bit addressable)
242 *
243 * @size: allocation size
244 *
245 * Allocate enough 32bit PA addressable pages to cover @size from the
246 * page level allocator and map them into continguos kernel virtual space.
247 */
248void *vmalloc_32(unsigned long size)
249{
250 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
251}
252
253void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
254{
255 BUG();
256 return NULL;
257}
258
259void vunmap(void *addr)
260{
261 BUG();
262}
263
264/*
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -0700265 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
266 * have one.
267 */
268void __attribute__((weak)) vmalloc_sync_all(void)
269{
270}
271
272/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 * sys_brk() for the most part doesn't need the global kernel
274 * lock, except when an application is doing something nasty
275 * like trying to un-brk an area that has already been mapped
276 * to a regular file. in this case, the unmapping will need
277 * to invoke file system routines that need the global lock.
278 */
279asmlinkage unsigned long sys_brk(unsigned long brk)
280{
281 struct mm_struct *mm = current->mm;
282
283 if (brk < mm->start_brk || brk > mm->context.end_brk)
284 return mm->brk;
285
286 if (mm->brk == brk)
287 return mm->brk;
288
289 /*
290 * Always allow shrinking brk
291 */
292 if (brk <= mm->brk) {
293 mm->brk = brk;
294 return brk;
295 }
296
297 /*
298 * Ok, looks good - let it rip.
299 */
300 return mm->brk = brk;
301}
302
303#ifdef DEBUG
304static void show_process_blocks(void)
305{
306 struct vm_list_struct *vml;
307
308 printk("Process blocks %d:", current->pid);
309
310 for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
311 printk(" %p: %p", vml, vml->vma);
312 if (vml->vma)
313 printk(" (%d @%lx #%d)",
314 kobjsize((void *) vml->vma->vm_start),
315 vml->vma->vm_start,
316 atomic_read(&vml->vma->vm_usage));
317 printk(vml->next ? " ->" : ".\n");
318 }
319}
320#endif /* DEBUG */
321
David Howells30340972006-09-27 01:50:20 -0700322/*
323 * add a VMA into a process's mm_struct in the appropriate place in the list
324 * - should be called with mm->mmap_sem held writelocked
325 */
326static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
327{
328 struct vm_list_struct **ppv;
329
330 for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
331 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
332 break;
333
334 vml->next = *ppv;
335 *ppv = vml;
336}
337
338/*
339 * look up the first VMA in which addr resides, NULL if none
340 * - should be called with mm->mmap_sem at least held readlocked
341 */
342struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
343{
344 struct vm_list_struct *loop, *vml;
345
346 /* search the vm_start ordered list */
347 vml = NULL;
348 for (loop = mm->context.vmlist; loop; loop = loop->next) {
349 if (loop->vma->vm_start > addr)
350 break;
351 vml = loop;
352 }
353
354 if (vml && vml->vma->vm_end > addr)
355 return vml->vma;
356
357 return NULL;
358}
359EXPORT_SYMBOL(find_vma);
360
361/*
David Howells930e6522006-09-27 01:50:22 -0700362 * find a VMA
363 * - we don't extend stack VMAs under NOMMU conditions
364 */
365struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
366{
367 return find_vma(mm, addr);
368}
369
370/*
David Howells6fa5f802006-09-27 01:50:21 -0700371 * look up the first VMA exactly that exactly matches addr
372 * - should be called with mm->mmap_sem at least held readlocked
373 */
374static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
375 unsigned long addr)
376{
377 struct vm_list_struct *vml;
378
379 /* search the vm_start ordered list */
380 for (vml = mm->context.vmlist; vml; vml = vml->next) {
381 if (vml->vma->vm_start == addr)
382 return vml->vma;
383 if (vml->vma->vm_start > addr)
384 break;
385 }
386
387 return NULL;
388}
389
390/*
David Howells30340972006-09-27 01:50:20 -0700391 * find a VMA in the global tree
392 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
394{
395 struct vm_area_struct *vma;
396 struct rb_node *n = nommu_vma_tree.rb_node;
397
398 while (n) {
399 vma = rb_entry(n, struct vm_area_struct, vm_rb);
400
401 if (start < vma->vm_start)
402 n = n->rb_left;
403 else if (start > vma->vm_start)
404 n = n->rb_right;
405 else
406 return vma;
407 }
408
409 return NULL;
410}
411
David Howells30340972006-09-27 01:50:20 -0700412/*
413 * add a VMA in the global tree
414 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415static void add_nommu_vma(struct vm_area_struct *vma)
416{
417 struct vm_area_struct *pvma;
418 struct address_space *mapping;
419 struct rb_node **p = &nommu_vma_tree.rb_node;
420 struct rb_node *parent = NULL;
421
422 /* add the VMA to the mapping */
423 if (vma->vm_file) {
424 mapping = vma->vm_file->f_mapping;
425
426 flush_dcache_mmap_lock(mapping);
427 vma_prio_tree_insert(vma, &mapping->i_mmap);
428 flush_dcache_mmap_unlock(mapping);
429 }
430
431 /* add the VMA to the master list */
432 while (*p) {
433 parent = *p;
434 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
435
436 if (vma->vm_start < pvma->vm_start) {
437 p = &(*p)->rb_left;
438 }
439 else if (vma->vm_start > pvma->vm_start) {
440 p = &(*p)->rb_right;
441 }
442 else {
443 /* mappings are at the same address - this can only
444 * happen for shared-mem chardevs and shared file
445 * mappings backed by ramfs/tmpfs */
446 BUG_ON(!(pvma->vm_flags & VM_SHARED));
447
448 if (vma < pvma)
449 p = &(*p)->rb_left;
450 else if (vma > pvma)
451 p = &(*p)->rb_right;
452 else
453 BUG();
454 }
455 }
456
457 rb_link_node(&vma->vm_rb, parent, p);
458 rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
459}
460
David Howells30340972006-09-27 01:50:20 -0700461/*
462 * delete a VMA from the global list
463 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464static void delete_nommu_vma(struct vm_area_struct *vma)
465{
466 struct address_space *mapping;
467
468 /* remove the VMA from the mapping */
469 if (vma->vm_file) {
470 mapping = vma->vm_file->f_mapping;
471
472 flush_dcache_mmap_lock(mapping);
473 vma_prio_tree_remove(vma, &mapping->i_mmap);
474 flush_dcache_mmap_unlock(mapping);
475 }
476
477 /* remove from the master list */
478 rb_erase(&vma->vm_rb, &nommu_vma_tree);
479}
480
481/*
482 * determine whether a mapping should be permitted and, if so, what sort of
483 * mapping we're capable of supporting
484 */
485static int validate_mmap_request(struct file *file,
486 unsigned long addr,
487 unsigned long len,
488 unsigned long prot,
489 unsigned long flags,
490 unsigned long pgoff,
491 unsigned long *_capabilities)
492{
493 unsigned long capabilities;
494 unsigned long reqprot = prot;
495 int ret;
496
497 /* do the simple checks first */
498 if (flags & MAP_FIXED || addr) {
499 printk(KERN_DEBUG
500 "%d: Can't do fixed-address/overlay mmap of RAM\n",
501 current->pid);
502 return -EINVAL;
503 }
504
505 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
506 (flags & MAP_TYPE) != MAP_SHARED)
507 return -EINVAL;
508
Mike Frysingerf81cff02006-12-06 12:02:59 +1000509 if (!len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 return -EINVAL;
511
Mike Frysingerf81cff02006-12-06 12:02:59 +1000512 /* Careful about overflows.. */
513 len = PAGE_ALIGN(len);
514 if (!len || len > TASK_SIZE)
515 return -ENOMEM;
516
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 /* offset overflow? */
518 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
Mike Frysingerf81cff02006-12-06 12:02:59 +1000519 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520
521 if (file) {
522 /* validate file mapping requests */
523 struct address_space *mapping;
524
525 /* files must support mmap */
526 if (!file->f_op || !file->f_op->mmap)
527 return -ENODEV;
528
529 /* work out if what we've got could possibly be shared
530 * - we support chardevs that provide their own "memory"
531 * - we support files/blockdevs that are memory backed
532 */
533 mapping = file->f_mapping;
534 if (!mapping)
Josef Sipeke9536ae2006-12-08 02:37:21 -0800535 mapping = file->f_path.dentry->d_inode->i_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536
537 capabilities = 0;
538 if (mapping && mapping->backing_dev_info)
539 capabilities = mapping->backing_dev_info->capabilities;
540
541 if (!capabilities) {
542 /* no explicit capabilities set, so assume some
543 * defaults */
Josef Sipeke9536ae2006-12-08 02:37:21 -0800544 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 case S_IFREG:
546 case S_IFBLK:
547 capabilities = BDI_CAP_MAP_COPY;
548 break;
549
550 case S_IFCHR:
551 capabilities =
552 BDI_CAP_MAP_DIRECT |
553 BDI_CAP_READ_MAP |
554 BDI_CAP_WRITE_MAP;
555 break;
556
557 default:
558 return -EINVAL;
559 }
560 }
561
562 /* eliminate any capabilities that we can't support on this
563 * device */
564 if (!file->f_op->get_unmapped_area)
565 capabilities &= ~BDI_CAP_MAP_DIRECT;
566 if (!file->f_op->read)
567 capabilities &= ~BDI_CAP_MAP_COPY;
568
569 if (flags & MAP_SHARED) {
570 /* do checks for writing, appending and locking */
571 if ((prot & PROT_WRITE) &&
572 !(file->f_mode & FMODE_WRITE))
573 return -EACCES;
574
Josef Sipeke9536ae2006-12-08 02:37:21 -0800575 if (IS_APPEND(file->f_path.dentry->d_inode) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 (file->f_mode & FMODE_WRITE))
577 return -EACCES;
578
Josef Sipeke9536ae2006-12-08 02:37:21 -0800579 if (locks_verify_locked(file->f_path.dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 return -EAGAIN;
581
582 if (!(capabilities & BDI_CAP_MAP_DIRECT))
583 return -ENODEV;
584
585 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
586 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
587 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
588 ) {
589 printk("MAP_SHARED not completely supported on !MMU\n");
590 return -EINVAL;
591 }
592
593 /* we mustn't privatise shared mappings */
594 capabilities &= ~BDI_CAP_MAP_COPY;
595 }
596 else {
597 /* we're going to read the file into private memory we
598 * allocate */
599 if (!(capabilities & BDI_CAP_MAP_COPY))
600 return -ENODEV;
601
602 /* we don't permit a private writable mapping to be
603 * shared with the backing device */
604 if (prot & PROT_WRITE)
605 capabilities &= ~BDI_CAP_MAP_DIRECT;
606 }
607
608 /* handle executable mappings and implied executable
609 * mappings */
Josef Sipeke9536ae2006-12-08 02:37:21 -0800610 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 if (prot & PROT_EXEC)
612 return -EPERM;
613 }
614 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
615 /* handle implication of PROT_EXEC by PROT_READ */
616 if (current->personality & READ_IMPLIES_EXEC) {
617 if (capabilities & BDI_CAP_EXEC_MAP)
618 prot |= PROT_EXEC;
619 }
620 }
621 else if ((prot & PROT_READ) &&
622 (prot & PROT_EXEC) &&
623 !(capabilities & BDI_CAP_EXEC_MAP)
624 ) {
625 /* backing file is not executable, try to copy */
626 capabilities &= ~BDI_CAP_MAP_DIRECT;
627 }
628 }
629 else {
630 /* anonymous mappings are always memory backed and can be
631 * privately mapped
632 */
633 capabilities = BDI_CAP_MAP_COPY;
634
635 /* handle PROT_EXEC implication by PROT_READ */
636 if ((prot & PROT_READ) &&
637 (current->personality & READ_IMPLIES_EXEC))
638 prot |= PROT_EXEC;
639 }
640
641 /* allow the security API to have its say */
642 ret = security_file_mmap(file, reqprot, prot, flags);
643 if (ret < 0)
644 return ret;
645
646 /* looks okay */
647 *_capabilities = capabilities;
648 return 0;
649}
650
651/*
652 * we've determined that we can make the mapping, now translate what we
653 * now know into VMA flags
654 */
655static unsigned long determine_vm_flags(struct file *file,
656 unsigned long prot,
657 unsigned long flags,
658 unsigned long capabilities)
659{
660 unsigned long vm_flags;
661
662 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
663 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
664 /* vm_flags |= mm->def_flags; */
665
666 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
667 /* attempt to share read-only copies of mapped file chunks */
668 if (file && !(prot & PROT_WRITE))
669 vm_flags |= VM_MAYSHARE;
670 }
671 else {
672 /* overlay a shareable mapping on the backing device or inode
673 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
674 * romfs/cramfs */
675 if (flags & MAP_SHARED)
676 vm_flags |= VM_MAYSHARE | VM_SHARED;
677 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
678 vm_flags |= VM_MAYSHARE;
679 }
680
681 /* refuse to let anyone share private mappings with this process if
682 * it's being traced - otherwise breakpoints set in it may interfere
683 * with another untraced process
684 */
685 if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
686 vm_flags &= ~VM_MAYSHARE;
687
688 return vm_flags;
689}
690
691/*
692 * set up a shared mapping on a file
693 */
694static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
695{
696 int ret;
697
698 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
699 if (ret != -ENOSYS)
700 return ret;
701
702 /* getting an ENOSYS error indicates that direct mmap isn't
703 * possible (as opposed to tried but failed) so we'll fall
704 * through to making a private copy of the data and mapping
705 * that if we can */
706 return -ENODEV;
707}
708
709/*
710 * set up a private mapping or an anonymous shared mapping
711 */
712static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
713{
714 void *base;
715 int ret;
716
717 /* invoke the file's mapping function so that it can keep track of
718 * shared mappings on devices or memory
719 * - VM_MAYSHARE will be set if it may attempt to share
720 */
721 if (vma->vm_file) {
722 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
723 if (ret != -ENOSYS) {
724 /* shouldn't return success if we're not sharing */
725 BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
726 return ret; /* success or a real error */
727 }
728
729 /* getting an ENOSYS error indicates that direct mmap isn't
730 * possible (as opposed to tried but failed) so we'll try to
731 * make a private copy of the data and map that instead */
732 }
733
734 /* allocate some memory to hold the mapping
735 * - note that this may not return a page-aligned address if the object
736 * we're allocating is smaller than a page
737 */
Nick Piggin84097512006-03-22 00:08:34 -0800738 base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 if (!base)
740 goto enomem;
741
742 vma->vm_start = (unsigned long) base;
743 vma->vm_end = vma->vm_start + len;
744 vma->vm_flags |= VM_MAPPED_COPY;
745
746#ifdef WARN_ON_SLACK
747 if (len + WARN_ON_SLACK <= kobjsize(result))
748 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
749 len, current->pid, kobjsize(result) - len);
750#endif
751
752 if (vma->vm_file) {
753 /* read the contents of a file into the copy */
754 mm_segment_t old_fs;
755 loff_t fpos;
756
757 fpos = vma->vm_pgoff;
758 fpos <<= PAGE_SHIFT;
759
760 old_fs = get_fs();
761 set_fs(KERNEL_DS);
762 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
763 set_fs(old_fs);
764
765 if (ret < 0)
766 goto error_free;
767
768 /* clear the last little bit */
769 if (ret < len)
770 memset(base + ret, 0, len - ret);
771
772 } else {
773 /* if it's an anonymous mapping, then just clear it */
774 memset(base, 0, len);
775 }
776
777 return 0;
778
779error_free:
780 kfree(base);
781 vma->vm_start = 0;
782 return ret;
783
784enomem:
785 printk("Allocation of length %lu from process %d failed\n",
786 len, current->pid);
787 show_free_areas();
788 return -ENOMEM;
789}
790
791/*
792 * handle mapping creation for uClinux
793 */
794unsigned long do_mmap_pgoff(struct file *file,
795 unsigned long addr,
796 unsigned long len,
797 unsigned long prot,
798 unsigned long flags,
799 unsigned long pgoff)
800{
801 struct vm_list_struct *vml = NULL;
802 struct vm_area_struct *vma = NULL;
803 struct rb_node *rb;
804 unsigned long capabilities, vm_flags;
805 void *result;
806 int ret;
807
808 /* decide whether we should attempt the mapping, and if so what sort of
809 * mapping */
810 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
811 &capabilities);
812 if (ret < 0)
813 return ret;
814
815 /* we've determined that we can make the mapping, now translate what we
816 * now know into VMA flags */
817 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
818
819 /* we're going to need to record the mapping if it works */
Burman Yan4668edc2006-12-06 20:38:51 -0800820 vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 if (!vml)
822 goto error_getting_vml;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823
824 down_write(&nommu_vma_sem);
825
826 /* if we want to share, we need to check for VMAs created by other
827 * mmap() calls that overlap with our proposed mapping
828 * - we can only share with an exact match on most regular files
829 * - shared mappings on character devices and memory backed files are
830 * permitted to overlap inexactly as far as we are concerned for in
831 * these cases, sharing is handled in the driver or filesystem rather
832 * than here
833 */
834 if (vm_flags & VM_MAYSHARE) {
835 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
836 unsigned long vmpglen;
837
David Howells165b2392007-03-22 00:11:24 -0800838 /* suppress VMA sharing for shared regions */
839 if (vm_flags & VM_SHARED &&
840 capabilities & BDI_CAP_MAP_DIRECT)
841 goto dont_share_VMAs;
842
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
844 vma = rb_entry(rb, struct vm_area_struct, vm_rb);
845
846 if (!(vma->vm_flags & VM_MAYSHARE))
847 continue;
848
849 /* search for overlapping mappings on the same file */
Josef Sipeke9536ae2006-12-08 02:37:21 -0800850 if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 continue;
852
853 if (vma->vm_pgoff >= pgoff + pglen)
854 continue;
855
856 vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
857 vmpglen >>= PAGE_SHIFT;
858 if (pgoff >= vma->vm_pgoff + vmpglen)
859 continue;
860
861 /* handle inexactly overlapping matches between mappings */
862 if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
863 if (!(capabilities & BDI_CAP_MAP_DIRECT))
864 goto sharing_violation;
865 continue;
866 }
867
868 /* we've found a VMA we can share */
869 atomic_inc(&vma->vm_usage);
870
871 vml->vma = vma;
872 result = (void *) vma->vm_start;
873 goto shared;
874 }
875
David Howells165b2392007-03-22 00:11:24 -0800876 dont_share_VMAs:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 vma = NULL;
878
879 /* obtain the address at which to make a shared mapping
880 * - this is the hook for quasi-memory character devices to
881 * tell us the location of a shared mapping
882 */
883 if (file && file->f_op->get_unmapped_area) {
884 addr = file->f_op->get_unmapped_area(file, addr, len,
885 pgoff, flags);
886 if (IS_ERR((void *) addr)) {
887 ret = addr;
888 if (ret != (unsigned long) -ENOSYS)
889 goto error;
890
891 /* the driver refused to tell us where to site
892 * the mapping so we'll have to attempt to copy
893 * it */
894 ret = (unsigned long) -ENODEV;
895 if (!(capabilities & BDI_CAP_MAP_COPY))
896 goto error;
897
898 capabilities &= ~BDI_CAP_MAP_DIRECT;
899 }
900 }
901 }
902
903 /* we're going to need a VMA struct as well */
Burman Yan4668edc2006-12-06 20:38:51 -0800904 vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 if (!vma)
906 goto error_getting_vma;
907
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 INIT_LIST_HEAD(&vma->anon_vma_node);
909 atomic_set(&vma->vm_usage, 1);
910 if (file)
911 get_file(file);
912 vma->vm_file = file;
913 vma->vm_flags = vm_flags;
914 vma->vm_start = addr;
915 vma->vm_end = addr + len;
916 vma->vm_pgoff = pgoff;
917
918 vml->vma = vma;
919
920 /* set up the mapping */
921 if (file && vma->vm_flags & VM_SHARED)
922 ret = do_mmap_shared_file(vma, len);
923 else
924 ret = do_mmap_private(vma, len);
925 if (ret < 0)
926 goto error;
927
928 /* okay... we have a mapping; now we have to register it */
929 result = (void *) vma->vm_start;
930
931 if (vma->vm_flags & VM_MAPPED_COPY) {
932 realalloc += kobjsize(result);
933 askedalloc += len;
934 }
935
936 realalloc += kobjsize(vma);
937 askedalloc += sizeof(*vma);
938
939 current->mm->total_vm += len >> PAGE_SHIFT;
940
941 add_nommu_vma(vma);
942
943 shared:
944 realalloc += kobjsize(vml);
945 askedalloc += sizeof(*vml);
946
David Howells30340972006-09-27 01:50:20 -0700947 add_vma_to_mm(current->mm, vml);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
949 up_write(&nommu_vma_sem);
950
951 if (prot & PROT_EXEC)
952 flush_icache_range((unsigned long) result,
953 (unsigned long) result + len);
954
955#ifdef DEBUG
956 printk("do_mmap:\n");
957 show_process_blocks();
958#endif
959
960 return (unsigned long) result;
961
962 error:
963 up_write(&nommu_vma_sem);
964 kfree(vml);
965 if (vma) {
Gavin Lambert3fcd03e2006-09-30 23:27:01 -0700966 if (vma->vm_file)
967 fput(vma->vm_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 kfree(vma);
969 }
970 return ret;
971
972 sharing_violation:
973 up_write(&nommu_vma_sem);
974 printk("Attempt to share mismatched mappings\n");
975 kfree(vml);
976 return -EINVAL;
977
978 error_getting_vma:
979 up_write(&nommu_vma_sem);
980 kfree(vml);
Greg Ungerer66aa2b42005-09-12 11:18:10 +1000981 printk("Allocation of vma for %lu byte allocation from process %d failed\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 len, current->pid);
983 show_free_areas();
984 return -ENOMEM;
985
986 error_getting_vml:
987 printk("Allocation of vml for %lu byte allocation from process %d failed\n",
988 len, current->pid);
989 show_free_areas();
990 return -ENOMEM;
991}
992
993/*
994 * handle mapping disposal for uClinux
995 */
996static void put_vma(struct vm_area_struct *vma)
997{
998 if (vma) {
999 down_write(&nommu_vma_sem);
1000
1001 if (atomic_dec_and_test(&vma->vm_usage)) {
1002 delete_nommu_vma(vma);
1003
1004 if (vma->vm_ops && vma->vm_ops->close)
1005 vma->vm_ops->close(vma);
1006
1007 /* IO memory and memory shared directly out of the pagecache from
1008 * ramfs/tmpfs mustn't be released here */
1009 if (vma->vm_flags & VM_MAPPED_COPY) {
1010 realalloc -= kobjsize((void *) vma->vm_start);
1011 askedalloc -= vma->vm_end - vma->vm_start;
1012 kfree((void *) vma->vm_start);
1013 }
1014
1015 realalloc -= kobjsize(vma);
1016 askedalloc -= sizeof(*vma);
1017
1018 if (vma->vm_file)
1019 fput(vma->vm_file);
1020 kfree(vma);
1021 }
1022
1023 up_write(&nommu_vma_sem);
1024 }
1025}
1026
David Howells30340972006-09-27 01:50:20 -07001027/*
1028 * release a mapping
1029 * - under NOMMU conditions the parameters must match exactly to the mapping to
1030 * be removed
1031 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1033{
1034 struct vm_list_struct *vml, **parent;
1035 unsigned long end = addr + len;
1036
1037#ifdef DEBUG
1038 printk("do_munmap:\n");
1039#endif
1040
David Howells30340972006-09-27 01:50:20 -07001041 for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1042 if ((*parent)->vma->vm_start > addr)
1043 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 if ((*parent)->vma->vm_start == addr &&
Greg Ungerer66aa2b42005-09-12 11:18:10 +10001045 ((len == 0) || ((*parent)->vma->vm_end == end)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 goto found;
David Howells30340972006-09-27 01:50:20 -07001047 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
1049 printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1050 current->pid, current->comm, (void *) addr);
1051 return -EINVAL;
1052
1053 found:
1054 vml = *parent;
1055
1056 put_vma(vml->vma);
1057
1058 *parent = vml->next;
1059 realalloc -= kobjsize(vml);
1060 askedalloc -= sizeof(*vml);
1061 kfree(vml);
Hugh Dickins365e9c872005-10-29 18:16:18 -07001062
1063 update_hiwater_vm(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 mm->total_vm -= len >> PAGE_SHIFT;
1065
1066#ifdef DEBUG
1067 show_process_blocks();
1068#endif
1069
1070 return 0;
1071}
1072
David Howells30340972006-09-27 01:50:20 -07001073asmlinkage long sys_munmap(unsigned long addr, size_t len)
1074{
1075 int ret;
1076 struct mm_struct *mm = current->mm;
1077
1078 down_write(&mm->mmap_sem);
1079 ret = do_munmap(mm, addr, len);
1080 up_write(&mm->mmap_sem);
1081 return ret;
1082}
1083
1084/*
1085 * Release all mappings
1086 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087void exit_mmap(struct mm_struct * mm)
1088{
1089 struct vm_list_struct *tmp;
1090
1091 if (mm) {
1092#ifdef DEBUG
1093 printk("Exit_mmap:\n");
1094#endif
1095
1096 mm->total_vm = 0;
1097
1098 while ((tmp = mm->context.vmlist)) {
1099 mm->context.vmlist = tmp->next;
1100 put_vma(tmp->vma);
1101
1102 realalloc -= kobjsize(tmp);
1103 askedalloc -= sizeof(*tmp);
1104 kfree(tmp);
1105 }
1106
1107#ifdef DEBUG
1108 show_process_blocks();
1109#endif
1110 }
1111}
1112
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113unsigned long do_brk(unsigned long addr, unsigned long len)
1114{
1115 return -ENOMEM;
1116}
1117
1118/*
David Howells6fa5f802006-09-27 01:50:21 -07001119 * expand (or shrink) an existing mapping, potentially moving it at the same
1120 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 *
David Howells6fa5f802006-09-27 01:50:21 -07001122 * under NOMMU conditions, we only permit changing a mapping's size, and only
1123 * as long as it stays within the hole allocated by the kmalloc() call in
1124 * do_mmap_pgoff() and the block is not shareable
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 *
David Howells6fa5f802006-09-27 01:50:21 -07001126 * MREMAP_FIXED is not supported under NOMMU conditions
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 */
1128unsigned long do_mremap(unsigned long addr,
1129 unsigned long old_len, unsigned long new_len,
1130 unsigned long flags, unsigned long new_addr)
1131{
David Howells6fa5f802006-09-27 01:50:21 -07001132 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133
1134 /* insanity checks first */
1135 if (new_len == 0)
1136 return (unsigned long) -EINVAL;
1137
1138 if (flags & MREMAP_FIXED && new_addr != addr)
1139 return (unsigned long) -EINVAL;
1140
David Howells6fa5f802006-09-27 01:50:21 -07001141 vma = find_vma_exact(current->mm, addr);
1142 if (!vma)
1143 return (unsigned long) -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
David Howells6fa5f802006-09-27 01:50:21 -07001145 if (vma->vm_end != vma->vm_start + old_len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 return (unsigned long) -EFAULT;
1147
David Howells6fa5f802006-09-27 01:50:21 -07001148 if (vma->vm_flags & VM_MAYSHARE)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 return (unsigned long) -EPERM;
1150
1151 if (new_len > kobjsize((void *) addr))
1152 return (unsigned long) -ENOMEM;
1153
1154 /* all checks complete - do it */
David Howells6fa5f802006-09-27 01:50:21 -07001155 vma->vm_end = vma->vm_start + new_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156
1157 askedalloc -= old_len;
1158 askedalloc += new_len;
1159
David Howells6fa5f802006-09-27 01:50:21 -07001160 return vma->vm_start;
1161}
1162
1163asmlinkage unsigned long sys_mremap(unsigned long addr,
1164 unsigned long old_len, unsigned long new_len,
1165 unsigned long flags, unsigned long new_addr)
1166{
1167 unsigned long ret;
1168
1169 down_write(&current->mm->mmap_sem);
1170 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1171 up_write(&current->mm->mmap_sem);
1172 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173}
1174
Linus Torvalds6aab3412005-11-28 14:34:23 -08001175struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001176 unsigned int foll_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177{
1178 return NULL;
1179}
1180
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1182 unsigned long to, unsigned long size, pgprot_t prot)
1183{
Greg Ungerer66aa2b42005-09-12 11:18:10 +10001184 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1185 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186}
Luke Yang22c4af42006-07-14 00:24:09 -07001187EXPORT_SYMBOL(remap_pfn_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188
1189void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1190{
1191}
1192
1193unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1194 unsigned long len, unsigned long pgoff, unsigned long flags)
1195{
1196 return -ENOMEM;
1197}
1198
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001199void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200{
1201}
1202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203void unmap_mapping_range(struct address_space *mapping,
1204 loff_t const holebegin, loff_t const holelen,
1205 int even_cows)
1206{
1207}
Luke Yang22c4af42006-07-14 00:24:09 -07001208EXPORT_SYMBOL(unmap_mapping_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
1210/*
David Howellsd56e03c2007-03-22 00:11:23 -08001211 * ask for an unmapped area at which to create a mapping on a file
1212 */
1213unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1214 unsigned long len, unsigned long pgoff,
1215 unsigned long flags)
1216{
1217 unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1218 unsigned long, unsigned long);
1219
1220 get_area = current->mm->get_unmapped_area;
1221 if (file && file->f_op && file->f_op->get_unmapped_area)
1222 get_area = file->f_op->get_unmapped_area;
1223
1224 if (!get_area)
1225 return -ENOSYS;
1226
1227 return get_area(file, addr, len, pgoff, flags);
1228}
1229
1230EXPORT_SYMBOL(get_unmapped_area);
1231
1232/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 * Check that a process has enough memory to allocate a new virtual
1234 * mapping. 0 means there is enough memory for the allocation to
1235 * succeed and -ENOMEM implies there is not.
1236 *
1237 * We currently support three overcommit policies, which are set via the
1238 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1239 *
1240 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1241 * Additional code 2002 Jul 20 by Robert Love.
1242 *
1243 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1244 *
1245 * Note this is a helper function intended to be used by LSMs which
1246 * wish to use this logic.
1247 */
1248int __vm_enough_memory(long pages, int cap_sys_admin)
1249{
1250 unsigned long free, allowed;
1251
1252 vm_acct_memory(pages);
1253
1254 /*
1255 * Sometimes we want to use more memory than we have
1256 */
1257 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1258 return 0;
1259
1260 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1261 unsigned long n;
1262
Christoph Lameter347ce432006-06-30 01:55:35 -07001263 free = global_page_state(NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 free += nr_swap_pages;
1265
1266 /*
1267 * Any slabs which are created with the
1268 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1269 * which are reclaimable, under pressure. The dentry
1270 * cache and most inode caches should fall into this
1271 */
Christoph Lameter972d1a72006-09-25 23:31:51 -07001272 free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273
1274 /*
1275 * Leave the last 3% for root
1276 */
1277 if (!cap_sys_admin)
1278 free -= free / 32;
1279
1280 if (free > pages)
1281 return 0;
1282
1283 /*
1284 * nr_free_pages() is very expensive on large systems,
1285 * only call if we're about to fail.
1286 */
1287 n = nr_free_pages();
Hideo AOKId5ddc792006-04-10 22:53:01 -07001288
1289 /*
1290 * Leave reserved pages. The pages are not for anonymous pages.
1291 */
1292 if (n <= totalreserve_pages)
1293 goto error;
1294 else
1295 n -= totalreserve_pages;
1296
1297 /*
1298 * Leave the last 3% for root
1299 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 if (!cap_sys_admin)
1301 n -= n / 32;
1302 free += n;
1303
1304 if (free > pages)
1305 return 0;
Hideo AOKId5ddc792006-04-10 22:53:01 -07001306
1307 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 }
1309
1310 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1311 /*
1312 * Leave the last 3% for root
1313 */
1314 if (!cap_sys_admin)
1315 allowed -= allowed / 32;
1316 allowed += total_swap_pages;
1317
1318 /* Don't let a single process grow too big:
1319 leave 3% of the size of this process for other processes */
1320 allowed -= current->mm->total_vm / 32;
1321
Simon Derr2f60f8d2005-08-04 19:52:03 -07001322 /*
1323 * cast `allowed' as a signed long because vm_committed_space
1324 * sometimes has a negative value
1325 */
1326 if (atomic_read(&vm_committed_space) < (long)allowed)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 return 0;
Hideo AOKId5ddc792006-04-10 22:53:01 -07001328error:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329 vm_unacct_memory(pages);
1330
1331 return -ENOMEM;
1332}
1333
1334int in_gate_area_no_task(unsigned long addr)
1335{
1336 return 0;
1337}
David Howellsb0e15192006-01-06 00:11:42 -08001338
1339struct page *filemap_nopage(struct vm_area_struct *area,
1340 unsigned long address, int *type)
1341{
1342 BUG();
1343 return NULL;
1344}
David Howells0ec76a12006-09-27 01:50:15 -07001345
1346/*
1347 * Access another process' address space.
1348 * - source/target buffer must be kernel space
1349 */
1350int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1351{
David Howells0ec76a12006-09-27 01:50:15 -07001352 struct vm_area_struct *vma;
1353 struct mm_struct *mm;
1354
1355 if (addr + len < addr)
1356 return 0;
1357
1358 mm = get_task_mm(tsk);
1359 if (!mm)
1360 return 0;
1361
1362 down_read(&mm->mmap_sem);
1363
1364 /* the access must start within one of the target process's mappings */
David Howells0159b142006-09-27 01:50:16 -07001365 vma = find_vma(mm, addr);
1366 if (vma) {
David Howells0ec76a12006-09-27 01:50:15 -07001367 /* don't overrun this mapping */
1368 if (addr + len >= vma->vm_end)
1369 len = vma->vm_end - addr;
1370
1371 /* only read or write mappings where it is permitted */
David Howellsd00c7b92006-09-27 01:50:19 -07001372 if (write && vma->vm_flags & VM_MAYWRITE)
David Howells0ec76a12006-09-27 01:50:15 -07001373 len -= copy_to_user((void *) addr, buf, len);
David Howellsd00c7b92006-09-27 01:50:19 -07001374 else if (!write && vma->vm_flags & VM_MAYREAD)
David Howells0ec76a12006-09-27 01:50:15 -07001375 len -= copy_from_user(buf, (void *) addr, len);
1376 else
1377 len = 0;
1378 } else {
1379 len = 0;
1380 }
1381
1382 up_read(&mm->mmap_sem);
1383 mmput(mm);
1384 return len;
1385}