nommu: Correct kobjsize() page validity checks.
[linux-2.6.git] / mm / nommu.c
1 /*
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  *  Copyright (c) 2007      Paul Mundt <lethal@linux-sh.org>
14  */
15
16 #include <linux/module.h>
17 #include <linux/mm.h>
18 #include <linux/mman.h>
19 #include <linux/swap.h>
20 #include <linux/file.h>
21 #include <linux/highmem.h>
22 #include <linux/pagemap.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/ptrace.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/mount.h>
29 #include <linux/personality.h>
30 #include <linux/security.h>
31 #include <linux/syscalls.h>
32
33 #include <asm/uaccess.h>
34 #include <asm/tlb.h>
35 #include <asm/tlbflush.h>
36
37 void *high_memory;
38 struct page *mem_map;
39 unsigned long max_mapnr;
40 unsigned long num_physpages;
41 unsigned long askedalloc, realalloc;
42 atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
43 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
44 int sysctl_overcommit_ratio = 50; /* default is 50% */
45 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
46 int heap_stack_gap = 0;
47
48 EXPORT_SYMBOL(mem_map);
49 EXPORT_SYMBOL(num_physpages);
50
51 /* list of shareable VMAs */
52 struct rb_root nommu_vma_tree = RB_ROOT;
53 DECLARE_RWSEM(nommu_vma_sem);
54
55 struct vm_operations_struct generic_file_vm_ops = {
56 };
57
58 /*
59  * Handle all mappings that got truncated by a "truncate()"
60  * system call.
61  *
62  * NOTE! We have to be ready to update the memory sharing
63  * between the file and the memory map for a potential last
64  * incomplete page.  Ugly, but necessary.
65  */
66 int vmtruncate(struct inode *inode, loff_t offset)
67 {
68         struct address_space *mapping = inode->i_mapping;
69         unsigned long limit;
70
71         if (inode->i_size < offset)
72                 goto do_expand;
73         i_size_write(inode, offset);
74
75         truncate_inode_pages(mapping, offset);
76         goto out_truncate;
77
78 do_expand:
79         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
80         if (limit != RLIM_INFINITY && offset > limit)
81                 goto out_sig;
82         if (offset > inode->i_sb->s_maxbytes)
83                 goto out;
84         i_size_write(inode, offset);
85
86 out_truncate:
87         if (inode->i_op && inode->i_op->truncate)
88                 inode->i_op->truncate(inode);
89         return 0;
90 out_sig:
91         send_sig(SIGXFSZ, current, 0);
92 out:
93         return -EFBIG;
94 }
95
96 EXPORT_SYMBOL(vmtruncate);
97
98 /*
99  * Return the total memory allocated for this pointer, not
100  * just what the caller asked for.
101  *
102  * Doesn't have to be accurate, i.e. may have races.
103  */
104 unsigned int kobjsize(const void *objp)
105 {
106         struct page *page;
107
108         /*
109          * If the object we have should not have ksize performed on it,
110          * return size of 0
111          */
112         if (!objp || !virt_addr_valid(objp))
113                 return 0;
114
115         page = virt_to_head_page(objp);
116
117         /*
118          * If the allocator sets PageSlab, we know the pointer came from
119          * kmalloc().
120          */
121         if (PageSlab(page))
122                 return ksize(objp);
123
124         /*
125          * The ksize() function is only guaranteed to work for pointers
126          * returned by kmalloc(). So handle arbitrary pointers here.
127          */
128         return PAGE_SIZE << compound_order(page);
129 }
130
131 /*
132  * get a list of pages in an address range belonging to the specified process
133  * and indicate the VMA that covers each page
134  * - this is potentially dodgy as we may end incrementing the page count of a
135  *   slab page or a secondary page from a compound page
136  * - don't permit access to VMAs that don't support it, such as I/O mappings
137  */
138 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
139         unsigned long start, int len, int write, int force,
140         struct page **pages, struct vm_area_struct **vmas)
141 {
142         struct vm_area_struct *vma;
143         unsigned long vm_flags;
144         int i;
145
146         /* calculate required read or write permissions.
147          * - if 'force' is set, we only require the "MAY" flags.
148          */
149         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
150         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
151
152         for (i = 0; i < len; i++) {
153                 vma = find_vma(mm, start);
154                 if (!vma)
155                         goto finish_or_fault;
156
157                 /* protect what we can, including chardevs */
158                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
159                     !(vm_flags & vma->vm_flags))
160                         goto finish_or_fault;
161
162                 if (pages) {
163                         pages[i] = virt_to_page(start);
164                         if (pages[i])
165                                 page_cache_get(pages[i]);
166                 }
167                 if (vmas)
168                         vmas[i] = vma;
169                 start += PAGE_SIZE;
170         }
171
172         return i;
173
174 finish_or_fault:
175         return i ? : -EFAULT;
176 }
177 EXPORT_SYMBOL(get_user_pages);
178
179 DEFINE_RWLOCK(vmlist_lock);
180 struct vm_struct *vmlist;
181
182 void vfree(const void *addr)
183 {
184         kfree(addr);
185 }
186 EXPORT_SYMBOL(vfree);
187
188 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
189 {
190         /*
191          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
192          * returns only a logical address.
193          */
194         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
195 }
196 EXPORT_SYMBOL(__vmalloc);
197
198 void *vmalloc_user(unsigned long size)
199 {
200         void *ret;
201
202         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
203                         PAGE_KERNEL);
204         if (ret) {
205                 struct vm_area_struct *vma;
206
207                 down_write(&current->mm->mmap_sem);
208                 vma = find_vma(current->mm, (unsigned long)ret);
209                 if (vma)
210                         vma->vm_flags |= VM_USERMAP;
211                 up_write(&current->mm->mmap_sem);
212         }
213
214         return ret;
215 }
216 EXPORT_SYMBOL(vmalloc_user);
217
218 struct page *vmalloc_to_page(const void *addr)
219 {
220         return virt_to_page(addr);
221 }
222 EXPORT_SYMBOL(vmalloc_to_page);
223
224 unsigned long vmalloc_to_pfn(const void *addr)
225 {
226         return page_to_pfn(virt_to_page(addr));
227 }
228 EXPORT_SYMBOL(vmalloc_to_pfn);
229
230 long vread(char *buf, char *addr, unsigned long count)
231 {
232         memcpy(buf, addr, count);
233         return count;
234 }
235
236 long vwrite(char *buf, char *addr, unsigned long count)
237 {
238         /* Don't allow overflow */
239         if ((unsigned long) addr + count < count)
240                 count = -(unsigned long) addr;
241
242         memcpy(addr, buf, count);
243         return(count);
244 }
245
246 /*
247  *      vmalloc  -  allocate virtually continguos memory
248  *
249  *      @size:          allocation size
250  *
251  *      Allocate enough pages to cover @size from the page level
252  *      allocator and map them into continguos kernel virtual space.
253  *
254  *      For tight control over page level allocator and protection flags
255  *      use __vmalloc() instead.
256  */
257 void *vmalloc(unsigned long size)
258 {
259        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
260 }
261 EXPORT_SYMBOL(vmalloc);
262
263 void *vmalloc_node(unsigned long size, int node)
264 {
265         return vmalloc(size);
266 }
267 EXPORT_SYMBOL(vmalloc_node);
268
269 /**
270  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
271  *      @size:          allocation size
272  *
273  *      Allocate enough 32bit PA addressable pages to cover @size from the
274  *      page level allocator and map them into continguos kernel virtual space.
275  */
276 void *vmalloc_32(unsigned long size)
277 {
278         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
279 }
280 EXPORT_SYMBOL(vmalloc_32);
281
282 /**
283  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
284  *      @size:          allocation size
285  *
286  * The resulting memory area is 32bit addressable and zeroed so it can be
287  * mapped to userspace without leaking data.
288  *
289  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
290  * remap_vmalloc_range() are permissible.
291  */
292 void *vmalloc_32_user(unsigned long size)
293 {
294         /*
295          * We'll have to sort out the ZONE_DMA bits for 64-bit,
296          * but for now this can simply use vmalloc_user() directly.
297          */
298         return vmalloc_user(size);
299 }
300 EXPORT_SYMBOL(vmalloc_32_user);
301
302 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
303 {
304         BUG();
305         return NULL;
306 }
307 EXPORT_SYMBOL(vmap);
308
309 void vunmap(const void *addr)
310 {
311         BUG();
312 }
313 EXPORT_SYMBOL(vunmap);
314
315 /*
316  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
317  * have one.
318  */
319 void  __attribute__((weak)) vmalloc_sync_all(void)
320 {
321 }
322
323 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
324                    struct page *page)
325 {
326         return -EINVAL;
327 }
328 EXPORT_SYMBOL(vm_insert_page);
329
330 /*
331  *  sys_brk() for the most part doesn't need the global kernel
332  *  lock, except when an application is doing something nasty
333  *  like trying to un-brk an area that has already been mapped
334  *  to a regular file.  in this case, the unmapping will need
335  *  to invoke file system routines that need the global lock.
336  */
337 asmlinkage unsigned long sys_brk(unsigned long brk)
338 {
339         struct mm_struct *mm = current->mm;
340
341         if (brk < mm->start_brk || brk > mm->context.end_brk)
342                 return mm->brk;
343
344         if (mm->brk == brk)
345                 return mm->brk;
346
347         /*
348          * Always allow shrinking brk
349          */
350         if (brk <= mm->brk) {
351                 mm->brk = brk;
352                 return brk;
353         }
354
355         /*
356          * Ok, looks good - let it rip.
357          */
358         return mm->brk = brk;
359 }
360
361 #ifdef DEBUG
362 static void show_process_blocks(void)
363 {
364         struct vm_list_struct *vml;
365
366         printk("Process blocks %d:", current->pid);
367
368         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
369                 printk(" %p: %p", vml, vml->vma);
370                 if (vml->vma)
371                         printk(" (%d @%lx #%d)",
372                                kobjsize((void *) vml->vma->vm_start),
373                                vml->vma->vm_start,
374                                atomic_read(&vml->vma->vm_usage));
375                 printk(vml->next ? " ->" : ".\n");
376         }
377 }
378 #endif /* DEBUG */
379
380 /*
381  * add a VMA into a process's mm_struct in the appropriate place in the list
382  * - should be called with mm->mmap_sem held writelocked
383  */
384 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
385 {
386         struct vm_list_struct **ppv;
387
388         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
389                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
390                         break;
391
392         vml->next = *ppv;
393         *ppv = vml;
394 }
395
396 /*
397  * look up the first VMA in which addr resides, NULL if none
398  * - should be called with mm->mmap_sem at least held readlocked
399  */
400 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
401 {
402         struct vm_list_struct *loop, *vml;
403
404         /* search the vm_start ordered list */
405         vml = NULL;
406         for (loop = mm->context.vmlist; loop; loop = loop->next) {
407                 if (loop->vma->vm_start > addr)
408                         break;
409                 vml = loop;
410         }
411
412         if (vml && vml->vma->vm_end > addr)
413                 return vml->vma;
414
415         return NULL;
416 }
417 EXPORT_SYMBOL(find_vma);
418
419 /*
420  * find a VMA
421  * - we don't extend stack VMAs under NOMMU conditions
422  */
423 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
424 {
425         return find_vma(mm, addr);
426 }
427
428 int expand_stack(struct vm_area_struct *vma, unsigned long address)
429 {
430         return -ENOMEM;
431 }
432
433 /*
434  * look up the first VMA exactly that exactly matches addr
435  * - should be called with mm->mmap_sem at least held readlocked
436  */
437 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
438                                                     unsigned long addr)
439 {
440         struct vm_list_struct *vml;
441
442         /* search the vm_start ordered list */
443         for (vml = mm->context.vmlist; vml; vml = vml->next) {
444                 if (vml->vma->vm_start == addr)
445                         return vml->vma;
446                 if (vml->vma->vm_start > addr)
447                         break;
448         }
449
450         return NULL;
451 }
452
453 /*
454  * find a VMA in the global tree
455  */
456 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
457 {
458         struct vm_area_struct *vma;
459         struct rb_node *n = nommu_vma_tree.rb_node;
460
461         while (n) {
462                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
463
464                 if (start < vma->vm_start)
465                         n = n->rb_left;
466                 else if (start > vma->vm_start)
467                         n = n->rb_right;
468                 else
469                         return vma;
470         }
471
472         return NULL;
473 }
474
475 /*
476  * add a VMA in the global tree
477  */
478 static void add_nommu_vma(struct vm_area_struct *vma)
479 {
480         struct vm_area_struct *pvma;
481         struct address_space *mapping;
482         struct rb_node **p = &nommu_vma_tree.rb_node;
483         struct rb_node *parent = NULL;
484
485         /* add the VMA to the mapping */
486         if (vma->vm_file) {
487                 mapping = vma->vm_file->f_mapping;
488
489                 flush_dcache_mmap_lock(mapping);
490                 vma_prio_tree_insert(vma, &mapping->i_mmap);
491                 flush_dcache_mmap_unlock(mapping);
492         }
493
494         /* add the VMA to the master list */
495         while (*p) {
496                 parent = *p;
497                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
498
499                 if (vma->vm_start < pvma->vm_start) {
500                         p = &(*p)->rb_left;
501                 }
502                 else if (vma->vm_start > pvma->vm_start) {
503                         p = &(*p)->rb_right;
504                 }
505                 else {
506                         /* mappings are at the same address - this can only
507                          * happen for shared-mem chardevs and shared file
508                          * mappings backed by ramfs/tmpfs */
509                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
510
511                         if (vma < pvma)
512                                 p = &(*p)->rb_left;
513                         else if (vma > pvma)
514                                 p = &(*p)->rb_right;
515                         else
516                                 BUG();
517                 }
518         }
519
520         rb_link_node(&vma->vm_rb, parent, p);
521         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
522 }
523
524 /*
525  * delete a VMA from the global list
526  */
527 static void delete_nommu_vma(struct vm_area_struct *vma)
528 {
529         struct address_space *mapping;
530
531         /* remove the VMA from the mapping */
532         if (vma->vm_file) {
533                 mapping = vma->vm_file->f_mapping;
534
535                 flush_dcache_mmap_lock(mapping);
536                 vma_prio_tree_remove(vma, &mapping->i_mmap);
537                 flush_dcache_mmap_unlock(mapping);
538         }
539
540         /* remove from the master list */
541         rb_erase(&vma->vm_rb, &nommu_vma_tree);
542 }
543
544 /*
545  * determine whether a mapping should be permitted and, if so, what sort of
546  * mapping we're capable of supporting
547  */
548 static int validate_mmap_request(struct file *file,
549                                  unsigned long addr,
550                                  unsigned long len,
551                                  unsigned long prot,
552                                  unsigned long flags,
553                                  unsigned long pgoff,
554                                  unsigned long *_capabilities)
555 {
556         unsigned long capabilities;
557         unsigned long reqprot = prot;
558         int ret;
559
560         /* do the simple checks first */
561         if (flags & MAP_FIXED || addr) {
562                 printk(KERN_DEBUG
563                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
564                        current->pid);
565                 return -EINVAL;
566         }
567
568         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
569             (flags & MAP_TYPE) != MAP_SHARED)
570                 return -EINVAL;
571
572         if (!len)
573                 return -EINVAL;
574
575         /* Careful about overflows.. */
576         len = PAGE_ALIGN(len);
577         if (!len || len > TASK_SIZE)
578                 return -ENOMEM;
579
580         /* offset overflow? */
581         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
582                 return -EOVERFLOW;
583
584         if (file) {
585                 /* validate file mapping requests */
586                 struct address_space *mapping;
587
588                 /* files must support mmap */
589                 if (!file->f_op || !file->f_op->mmap)
590                         return -ENODEV;
591
592                 /* work out if what we've got could possibly be shared
593                  * - we support chardevs that provide their own "memory"
594                  * - we support files/blockdevs that are memory backed
595                  */
596                 mapping = file->f_mapping;
597                 if (!mapping)
598                         mapping = file->f_path.dentry->d_inode->i_mapping;
599
600                 capabilities = 0;
601                 if (mapping && mapping->backing_dev_info)
602                         capabilities = mapping->backing_dev_info->capabilities;
603
604                 if (!capabilities) {
605                         /* no explicit capabilities set, so assume some
606                          * defaults */
607                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
608                         case S_IFREG:
609                         case S_IFBLK:
610                                 capabilities = BDI_CAP_MAP_COPY;
611                                 break;
612
613                         case S_IFCHR:
614                                 capabilities =
615                                         BDI_CAP_MAP_DIRECT |
616                                         BDI_CAP_READ_MAP |
617                                         BDI_CAP_WRITE_MAP;
618                                 break;
619
620                         default:
621                                 return -EINVAL;
622                         }
623                 }
624
625                 /* eliminate any capabilities that we can't support on this
626                  * device */
627                 if (!file->f_op->get_unmapped_area)
628                         capabilities &= ~BDI_CAP_MAP_DIRECT;
629                 if (!file->f_op->read)
630                         capabilities &= ~BDI_CAP_MAP_COPY;
631
632                 if (flags & MAP_SHARED) {
633                         /* do checks for writing, appending and locking */
634                         if ((prot & PROT_WRITE) &&
635                             !(file->f_mode & FMODE_WRITE))
636                                 return -EACCES;
637
638                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
639                             (file->f_mode & FMODE_WRITE))
640                                 return -EACCES;
641
642                         if (locks_verify_locked(file->f_path.dentry->d_inode))
643                                 return -EAGAIN;
644
645                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
646                                 return -ENODEV;
647
648                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
649                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
650                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
651                             ) {
652                                 printk("MAP_SHARED not completely supported on !MMU\n");
653                                 return -EINVAL;
654                         }
655
656                         /* we mustn't privatise shared mappings */
657                         capabilities &= ~BDI_CAP_MAP_COPY;
658                 }
659                 else {
660                         /* we're going to read the file into private memory we
661                          * allocate */
662                         if (!(capabilities & BDI_CAP_MAP_COPY))
663                                 return -ENODEV;
664
665                         /* we don't permit a private writable mapping to be
666                          * shared with the backing device */
667                         if (prot & PROT_WRITE)
668                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
669                 }
670
671                 /* handle executable mappings and implied executable
672                  * mappings */
673                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
674                         if (prot & PROT_EXEC)
675                                 return -EPERM;
676                 }
677                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
678                         /* handle implication of PROT_EXEC by PROT_READ */
679                         if (current->personality & READ_IMPLIES_EXEC) {
680                                 if (capabilities & BDI_CAP_EXEC_MAP)
681                                         prot |= PROT_EXEC;
682                         }
683                 }
684                 else if ((prot & PROT_READ) &&
685                          (prot & PROT_EXEC) &&
686                          !(capabilities & BDI_CAP_EXEC_MAP)
687                          ) {
688                         /* backing file is not executable, try to copy */
689                         capabilities &= ~BDI_CAP_MAP_DIRECT;
690                 }
691         }
692         else {
693                 /* anonymous mappings are always memory backed and can be
694                  * privately mapped
695                  */
696                 capabilities = BDI_CAP_MAP_COPY;
697
698                 /* handle PROT_EXEC implication by PROT_READ */
699                 if ((prot & PROT_READ) &&
700                     (current->personality & READ_IMPLIES_EXEC))
701                         prot |= PROT_EXEC;
702         }
703
704         /* allow the security API to have its say */
705         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
706         if (ret < 0)
707                 return ret;
708
709         /* looks okay */
710         *_capabilities = capabilities;
711         return 0;
712 }
713
714 /*
715  * we've determined that we can make the mapping, now translate what we
716  * now know into VMA flags
717  */
718 static unsigned long determine_vm_flags(struct file *file,
719                                         unsigned long prot,
720                                         unsigned long flags,
721                                         unsigned long capabilities)
722 {
723         unsigned long vm_flags;
724
725         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
726         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
727         /* vm_flags |= mm->def_flags; */
728
729         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
730                 /* attempt to share read-only copies of mapped file chunks */
731                 if (file && !(prot & PROT_WRITE))
732                         vm_flags |= VM_MAYSHARE;
733         }
734         else {
735                 /* overlay a shareable mapping on the backing device or inode
736                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
737                  * romfs/cramfs */
738                 if (flags & MAP_SHARED)
739                         vm_flags |= VM_MAYSHARE | VM_SHARED;
740                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
741                         vm_flags |= VM_MAYSHARE;
742         }
743
744         /* refuse to let anyone share private mappings with this process if
745          * it's being traced - otherwise breakpoints set in it may interfere
746          * with another untraced process
747          */
748         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
749                 vm_flags &= ~VM_MAYSHARE;
750
751         return vm_flags;
752 }
753
754 /*
755  * set up a shared mapping on a file
756  */
757 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
758 {
759         int ret;
760
761         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
762         if (ret != -ENOSYS)
763                 return ret;
764
765         /* getting an ENOSYS error indicates that direct mmap isn't
766          * possible (as opposed to tried but failed) so we'll fall
767          * through to making a private copy of the data and mapping
768          * that if we can */
769         return -ENODEV;
770 }
771
772 /*
773  * set up a private mapping or an anonymous shared mapping
774  */
775 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
776 {
777         void *base;
778         int ret;
779
780         /* invoke the file's mapping function so that it can keep track of
781          * shared mappings on devices or memory
782          * - VM_MAYSHARE will be set if it may attempt to share
783          */
784         if (vma->vm_file) {
785                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
786                 if (ret != -ENOSYS) {
787                         /* shouldn't return success if we're not sharing */
788                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
789                         return ret; /* success or a real error */
790                 }
791
792                 /* getting an ENOSYS error indicates that direct mmap isn't
793                  * possible (as opposed to tried but failed) so we'll try to
794                  * make a private copy of the data and map that instead */
795         }
796
797         /* allocate some memory to hold the mapping
798          * - note that this may not return a page-aligned address if the object
799          *   we're allocating is smaller than a page
800          */
801         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
802         if (!base)
803                 goto enomem;
804
805         vma->vm_start = (unsigned long) base;
806         vma->vm_end = vma->vm_start + len;
807         vma->vm_flags |= VM_MAPPED_COPY;
808
809 #ifdef WARN_ON_SLACK
810         if (len + WARN_ON_SLACK <= kobjsize(result))
811                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
812                        len, current->pid, kobjsize(result) - len);
813 #endif
814
815         if (vma->vm_file) {
816                 /* read the contents of a file into the copy */
817                 mm_segment_t old_fs;
818                 loff_t fpos;
819
820                 fpos = vma->vm_pgoff;
821                 fpos <<= PAGE_SHIFT;
822
823                 old_fs = get_fs();
824                 set_fs(KERNEL_DS);
825                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
826                 set_fs(old_fs);
827
828                 if (ret < 0)
829                         goto error_free;
830
831                 /* clear the last little bit */
832                 if (ret < len)
833                         memset(base + ret, 0, len - ret);
834
835         } else {
836                 /* if it's an anonymous mapping, then just clear it */
837                 memset(base, 0, len);
838         }
839
840         return 0;
841
842 error_free:
843         kfree(base);
844         vma->vm_start = 0;
845         return ret;
846
847 enomem:
848         printk("Allocation of length %lu from process %d failed\n",
849                len, current->pid);
850         show_free_areas();
851         return -ENOMEM;
852 }
853
854 /*
855  * handle mapping creation for uClinux
856  */
857 unsigned long do_mmap_pgoff(struct file *file,
858                             unsigned long addr,
859                             unsigned long len,
860                             unsigned long prot,
861                             unsigned long flags,
862                             unsigned long pgoff)
863 {
864         struct vm_list_struct *vml = NULL;
865         struct vm_area_struct *vma = NULL;
866         struct rb_node *rb;
867         unsigned long capabilities, vm_flags;
868         void *result;
869         int ret;
870
871         if (!(flags & MAP_FIXED))
872                 addr = round_hint_to_min(addr);
873
874         /* decide whether we should attempt the mapping, and if so what sort of
875          * mapping */
876         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
877                                     &capabilities);
878         if (ret < 0)
879                 return ret;
880
881         /* we've determined that we can make the mapping, now translate what we
882          * now know into VMA flags */
883         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
884
885         /* we're going to need to record the mapping if it works */
886         vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
887         if (!vml)
888                 goto error_getting_vml;
889
890         down_write(&nommu_vma_sem);
891
892         /* if we want to share, we need to check for VMAs created by other
893          * mmap() calls that overlap with our proposed mapping
894          * - we can only share with an exact match on most regular files
895          * - shared mappings on character devices and memory backed files are
896          *   permitted to overlap inexactly as far as we are concerned for in
897          *   these cases, sharing is handled in the driver or filesystem rather
898          *   than here
899          */
900         if (vm_flags & VM_MAYSHARE) {
901                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
902                 unsigned long vmpglen;
903
904                 /* suppress VMA sharing for shared regions */
905                 if (vm_flags & VM_SHARED &&
906                     capabilities & BDI_CAP_MAP_DIRECT)
907                         goto dont_share_VMAs;
908
909                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
910                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
911
912                         if (!(vma->vm_flags & VM_MAYSHARE))
913                                 continue;
914
915                         /* search for overlapping mappings on the same file */
916                         if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
917                                 continue;
918
919                         if (vma->vm_pgoff >= pgoff + pglen)
920                                 continue;
921
922                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
923                         vmpglen >>= PAGE_SHIFT;
924                         if (pgoff >= vma->vm_pgoff + vmpglen)
925                                 continue;
926
927                         /* handle inexactly overlapping matches between mappings */
928                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
929                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
930                                         goto sharing_violation;
931                                 continue;
932                         }
933
934                         /* we've found a VMA we can share */
935                         atomic_inc(&vma->vm_usage);
936
937                         vml->vma = vma;
938                         result = (void *) vma->vm_start;
939                         goto shared;
940                 }
941
942         dont_share_VMAs:
943                 vma = NULL;
944
945                 /* obtain the address at which to make a shared mapping
946                  * - this is the hook for quasi-memory character devices to
947                  *   tell us the location of a shared mapping
948                  */
949                 if (file && file->f_op->get_unmapped_area) {
950                         addr = file->f_op->get_unmapped_area(file, addr, len,
951                                                              pgoff, flags);
952                         if (IS_ERR((void *) addr)) {
953                                 ret = addr;
954                                 if (ret != (unsigned long) -ENOSYS)
955                                         goto error;
956
957                                 /* the driver refused to tell us where to site
958                                  * the mapping so we'll have to attempt to copy
959                                  * it */
960                                 ret = (unsigned long) -ENODEV;
961                                 if (!(capabilities & BDI_CAP_MAP_COPY))
962                                         goto error;
963
964                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
965                         }
966                 }
967         }
968
969         /* we're going to need a VMA struct as well */
970         vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
971         if (!vma)
972                 goto error_getting_vma;
973
974         INIT_LIST_HEAD(&vma->anon_vma_node);
975         atomic_set(&vma->vm_usage, 1);
976         if (file) {
977                 get_file(file);
978                 if (vm_flags & VM_EXECUTABLE) {
979                         added_exe_file_vma(current->mm);
980                         vma->vm_mm = current->mm;
981                 }
982         }
983         vma->vm_file    = file;
984         vma->vm_flags   = vm_flags;
985         vma->vm_start   = addr;
986         vma->vm_end     = addr + len;
987         vma->vm_pgoff   = pgoff;
988
989         vml->vma = vma;
990
991         /* set up the mapping */
992         if (file && vma->vm_flags & VM_SHARED)
993                 ret = do_mmap_shared_file(vma, len);
994         else
995                 ret = do_mmap_private(vma, len);
996         if (ret < 0)
997                 goto error;
998
999         /* okay... we have a mapping; now we have to register it */
1000         result = (void *) vma->vm_start;
1001
1002         if (vma->vm_flags & VM_MAPPED_COPY) {
1003                 realalloc += kobjsize(result);
1004                 askedalloc += len;
1005         }
1006
1007         realalloc += kobjsize(vma);
1008         askedalloc += sizeof(*vma);
1009
1010         current->mm->total_vm += len >> PAGE_SHIFT;
1011
1012         add_nommu_vma(vma);
1013
1014  shared:
1015         realalloc += kobjsize(vml);
1016         askedalloc += sizeof(*vml);
1017
1018         add_vma_to_mm(current->mm, vml);
1019
1020         up_write(&nommu_vma_sem);
1021
1022         if (prot & PROT_EXEC)
1023                 flush_icache_range((unsigned long) result,
1024                                    (unsigned long) result + len);
1025
1026 #ifdef DEBUG
1027         printk("do_mmap:\n");
1028         show_process_blocks();
1029 #endif
1030
1031         return (unsigned long) result;
1032
1033  error:
1034         up_write(&nommu_vma_sem);
1035         kfree(vml);
1036         if (vma) {
1037                 if (vma->vm_file) {
1038                         fput(vma->vm_file);
1039                         if (vma->vm_flags & VM_EXECUTABLE)
1040                                 removed_exe_file_vma(vma->vm_mm);
1041                 }
1042                 kfree(vma);
1043         }
1044         return ret;
1045
1046  sharing_violation:
1047         up_write(&nommu_vma_sem);
1048         printk("Attempt to share mismatched mappings\n");
1049         kfree(vml);
1050         return -EINVAL;
1051
1052  error_getting_vma:
1053         up_write(&nommu_vma_sem);
1054         kfree(vml);
1055         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
1056                len, current->pid);
1057         show_free_areas();
1058         return -ENOMEM;
1059
1060  error_getting_vml:
1061         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
1062                len, current->pid);
1063         show_free_areas();
1064         return -ENOMEM;
1065 }
1066 EXPORT_SYMBOL(do_mmap_pgoff);
1067
1068 /*
1069  * handle mapping disposal for uClinux
1070  */
1071 static void put_vma(struct mm_struct *mm, struct vm_area_struct *vma)
1072 {
1073         if (vma) {
1074                 down_write(&nommu_vma_sem);
1075
1076                 if (atomic_dec_and_test(&vma->vm_usage)) {
1077                         delete_nommu_vma(vma);
1078
1079                         if (vma->vm_ops && vma->vm_ops->close)
1080                                 vma->vm_ops->close(vma);
1081
1082                         /* IO memory and memory shared directly out of the pagecache from
1083                          * ramfs/tmpfs mustn't be released here */
1084                         if (vma->vm_flags & VM_MAPPED_COPY) {
1085                                 realalloc -= kobjsize((void *) vma->vm_start);
1086                                 askedalloc -= vma->vm_end - vma->vm_start;
1087                                 kfree((void *) vma->vm_start);
1088                         }
1089
1090                         realalloc -= kobjsize(vma);
1091                         askedalloc -= sizeof(*vma);
1092
1093                         if (vma->vm_file) {
1094                                 fput(vma->vm_file);
1095                                 if (vma->vm_flags & VM_EXECUTABLE)
1096                                         removed_exe_file_vma(mm);
1097                         }
1098                         kfree(vma);
1099                 }
1100
1101                 up_write(&nommu_vma_sem);
1102         }
1103 }
1104
1105 /*
1106  * release a mapping
1107  * - under NOMMU conditions the parameters must match exactly to the mapping to
1108  *   be removed
1109  */
1110 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1111 {
1112         struct vm_list_struct *vml, **parent;
1113         unsigned long end = addr + len;
1114
1115 #ifdef DEBUG
1116         printk("do_munmap:\n");
1117 #endif
1118
1119         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1120                 if ((*parent)->vma->vm_start > addr)
1121                         break;
1122                 if ((*parent)->vma->vm_start == addr &&
1123                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1124                         goto found;
1125         }
1126
1127         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1128                current->pid, current->comm, (void *) addr);
1129         return -EINVAL;
1130
1131  found:
1132         vml = *parent;
1133
1134         put_vma(mm, vml->vma);
1135
1136         *parent = vml->next;
1137         realalloc -= kobjsize(vml);
1138         askedalloc -= sizeof(*vml);
1139         kfree(vml);
1140
1141         update_hiwater_vm(mm);
1142         mm->total_vm -= len >> PAGE_SHIFT;
1143
1144 #ifdef DEBUG
1145         show_process_blocks();
1146 #endif
1147
1148         return 0;
1149 }
1150 EXPORT_SYMBOL(do_munmap);
1151
1152 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1153 {
1154         int ret;
1155         struct mm_struct *mm = current->mm;
1156
1157         down_write(&mm->mmap_sem);
1158         ret = do_munmap(mm, addr, len);
1159         up_write(&mm->mmap_sem);
1160         return ret;
1161 }
1162
1163 /*
1164  * Release all mappings
1165  */
1166 void exit_mmap(struct mm_struct * mm)
1167 {
1168         struct vm_list_struct *tmp;
1169
1170         if (mm) {
1171 #ifdef DEBUG
1172                 printk("Exit_mmap:\n");
1173 #endif
1174
1175                 mm->total_vm = 0;
1176
1177                 while ((tmp = mm->context.vmlist)) {
1178                         mm->context.vmlist = tmp->next;
1179                         put_vma(mm, tmp->vma);
1180
1181                         realalloc -= kobjsize(tmp);
1182                         askedalloc -= sizeof(*tmp);
1183                         kfree(tmp);
1184                 }
1185
1186 #ifdef DEBUG
1187                 show_process_blocks();
1188 #endif
1189         }
1190 }
1191
1192 unsigned long do_brk(unsigned long addr, unsigned long len)
1193 {
1194         return -ENOMEM;
1195 }
1196
1197 /*
1198  * expand (or shrink) an existing mapping, potentially moving it at the same
1199  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1200  *
1201  * under NOMMU conditions, we only permit changing a mapping's size, and only
1202  * as long as it stays within the hole allocated by the kmalloc() call in
1203  * do_mmap_pgoff() and the block is not shareable
1204  *
1205  * MREMAP_FIXED is not supported under NOMMU conditions
1206  */
1207 unsigned long do_mremap(unsigned long addr,
1208                         unsigned long old_len, unsigned long new_len,
1209                         unsigned long flags, unsigned long new_addr)
1210 {
1211         struct vm_area_struct *vma;
1212
1213         /* insanity checks first */
1214         if (new_len == 0)
1215                 return (unsigned long) -EINVAL;
1216
1217         if (flags & MREMAP_FIXED && new_addr != addr)
1218                 return (unsigned long) -EINVAL;
1219
1220         vma = find_vma_exact(current->mm, addr);
1221         if (!vma)
1222                 return (unsigned long) -EINVAL;
1223
1224         if (vma->vm_end != vma->vm_start + old_len)
1225                 return (unsigned long) -EFAULT;
1226
1227         if (vma->vm_flags & VM_MAYSHARE)
1228                 return (unsigned long) -EPERM;
1229
1230         if (new_len > kobjsize((void *) addr))
1231                 return (unsigned long) -ENOMEM;
1232
1233         /* all checks complete - do it */
1234         vma->vm_end = vma->vm_start + new_len;
1235
1236         askedalloc -= old_len;
1237         askedalloc += new_len;
1238
1239         return vma->vm_start;
1240 }
1241 EXPORT_SYMBOL(do_mremap);
1242
1243 asmlinkage unsigned long sys_mremap(unsigned long addr,
1244         unsigned long old_len, unsigned long new_len,
1245         unsigned long flags, unsigned long new_addr)
1246 {
1247         unsigned long ret;
1248
1249         down_write(&current->mm->mmap_sem);
1250         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1251         up_write(&current->mm->mmap_sem);
1252         return ret;
1253 }
1254
1255 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1256                         unsigned int foll_flags)
1257 {
1258         return NULL;
1259 }
1260
1261 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1262                 unsigned long to, unsigned long size, pgprot_t prot)
1263 {
1264         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1265         return 0;
1266 }
1267 EXPORT_SYMBOL(remap_pfn_range);
1268
1269 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1270                         unsigned long pgoff)
1271 {
1272         unsigned int size = vma->vm_end - vma->vm_start;
1273
1274         if (!(vma->vm_flags & VM_USERMAP))
1275                 return -EINVAL;
1276
1277         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1278         vma->vm_end = vma->vm_start + size;
1279
1280         return 0;
1281 }
1282 EXPORT_SYMBOL(remap_vmalloc_range);
1283
1284 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1285 {
1286 }
1287
1288 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1289         unsigned long len, unsigned long pgoff, unsigned long flags)
1290 {
1291         return -ENOMEM;
1292 }
1293
1294 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1295 {
1296 }
1297
1298 void unmap_mapping_range(struct address_space *mapping,
1299                          loff_t const holebegin, loff_t const holelen,
1300                          int even_cows)
1301 {
1302 }
1303 EXPORT_SYMBOL(unmap_mapping_range);
1304
1305 /*
1306  * ask for an unmapped area at which to create a mapping on a file
1307  */
1308 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1309                                 unsigned long len, unsigned long pgoff,
1310                                 unsigned long flags)
1311 {
1312         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1313                                   unsigned long, unsigned long);
1314
1315         get_area = current->mm->get_unmapped_area;
1316         if (file && file->f_op && file->f_op->get_unmapped_area)
1317                 get_area = file->f_op->get_unmapped_area;
1318
1319         if (!get_area)
1320                 return -ENOSYS;
1321
1322         return get_area(file, addr, len, pgoff, flags);
1323 }
1324 EXPORT_SYMBOL(get_unmapped_area);
1325
1326 /*
1327  * Check that a process has enough memory to allocate a new virtual
1328  * mapping. 0 means there is enough memory for the allocation to
1329  * succeed and -ENOMEM implies there is not.
1330  *
1331  * We currently support three overcommit policies, which are set via the
1332  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1333  *
1334  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1335  * Additional code 2002 Jul 20 by Robert Love.
1336  *
1337  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1338  *
1339  * Note this is a helper function intended to be used by LSMs which
1340  * wish to use this logic.
1341  */
1342 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1343 {
1344         unsigned long free, allowed;
1345
1346         vm_acct_memory(pages);
1347
1348         /*
1349          * Sometimes we want to use more memory than we have
1350          */
1351         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1352                 return 0;
1353
1354         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1355                 unsigned long n;
1356
1357                 free = global_page_state(NR_FILE_PAGES);
1358                 free += nr_swap_pages;
1359
1360                 /*
1361                  * Any slabs which are created with the
1362                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1363                  * which are reclaimable, under pressure.  The dentry
1364                  * cache and most inode caches should fall into this
1365                  */
1366                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1367
1368                 /*
1369                  * Leave the last 3% for root
1370                  */
1371                 if (!cap_sys_admin)
1372                         free -= free / 32;
1373
1374                 if (free > pages)
1375                         return 0;
1376
1377                 /*
1378                  * nr_free_pages() is very expensive on large systems,
1379                  * only call if we're about to fail.
1380                  */
1381                 n = nr_free_pages();
1382
1383                 /*
1384                  * Leave reserved pages. The pages are not for anonymous pages.
1385                  */
1386                 if (n <= totalreserve_pages)
1387                         goto error;
1388                 else
1389                         n -= totalreserve_pages;
1390
1391                 /*
1392                  * Leave the last 3% for root
1393                  */
1394                 if (!cap_sys_admin)
1395                         n -= n / 32;
1396                 free += n;
1397
1398                 if (free > pages)
1399                         return 0;
1400
1401                 goto error;
1402         }
1403
1404         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1405         /*
1406          * Leave the last 3% for root
1407          */
1408         if (!cap_sys_admin)
1409                 allowed -= allowed / 32;
1410         allowed += total_swap_pages;
1411
1412         /* Don't let a single process grow too big:
1413            leave 3% of the size of this process for other processes */
1414         allowed -= current->mm->total_vm / 32;
1415
1416         /*
1417          * cast `allowed' as a signed long because vm_committed_space
1418          * sometimes has a negative value
1419          */
1420         if (atomic_long_read(&vm_committed_space) < (long)allowed)
1421                 return 0;
1422 error:
1423         vm_unacct_memory(pages);
1424
1425         return -ENOMEM;
1426 }
1427
1428 int in_gate_area_no_task(unsigned long addr)
1429 {
1430         return 0;
1431 }
1432
1433 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1434 {
1435         BUG();
1436         return 0;
1437 }
1438 EXPORT_SYMBOL(filemap_fault);
1439
1440 /*
1441  * Access another process' address space.
1442  * - source/target buffer must be kernel space
1443  */
1444 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1445 {
1446         struct vm_area_struct *vma;
1447         struct mm_struct *mm;
1448
1449         if (addr + len < addr)
1450                 return 0;
1451
1452         mm = get_task_mm(tsk);
1453         if (!mm)
1454                 return 0;
1455
1456         down_read(&mm->mmap_sem);
1457
1458         /* the access must start within one of the target process's mappings */
1459         vma = find_vma(mm, addr);
1460         if (vma) {
1461                 /* don't overrun this mapping */
1462                 if (addr + len >= vma->vm_end)
1463                         len = vma->vm_end - addr;
1464
1465                 /* only read or write mappings where it is permitted */
1466                 if (write && vma->vm_flags & VM_MAYWRITE)
1467                         len -= copy_to_user((void *) addr, buf, len);
1468                 else if (!write && vma->vm_flags & VM_MAYREAD)
1469                         len -= copy_from_user(buf, (void *) addr, len);
1470                 else
1471                         len = 0;
1472         } else {
1473                 len = 0;
1474         }
1475
1476         up_read(&mm->mmap_sem);
1477         mmput(mm);
1478         return len;
1479 }