NOMMU: Teach kobjsize() about VMA regions.
[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) 2004-2008 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) 2007-2008 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/tracehook.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 #include "internal.h"
37
38 static inline __attribute__((format(printf, 1, 2)))
39 void no_printk(const char *fmt, ...)
40 {
41 }
42
43 #if 0
44 #define kenter(FMT, ...) \
45         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
46 #define kleave(FMT, ...) \
47         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
48 #define kdebug(FMT, ...) \
49         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
50 #else
51 #define kenter(FMT, ...) \
52         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
53 #define kleave(FMT, ...) \
54         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
55 #define kdebug(FMT, ...) \
56         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
57 #endif
58
59 #include "internal.h"
60
61 void *high_memory;
62 struct page *mem_map;
63 unsigned long max_mapnr;
64 unsigned long num_physpages;
65 atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
66 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
67 int sysctl_overcommit_ratio = 50; /* default is 50% */
68 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
69 int sysctl_nr_trim_pages = 1; /* page trimming behaviour */
70 int heap_stack_gap = 0;
71
72 atomic_t mmap_pages_allocated;
73
74 EXPORT_SYMBOL(mem_map);
75 EXPORT_SYMBOL(num_physpages);
76
77 /* list of mapped, potentially shareable regions */
78 static struct kmem_cache *vm_region_jar;
79 struct rb_root nommu_region_tree = RB_ROOT;
80 DECLARE_RWSEM(nommu_region_sem);
81
82 struct vm_operations_struct generic_file_vm_ops = {
83 };
84
85 /*
86  * Handle all mappings that got truncated by a "truncate()"
87  * system call.
88  *
89  * NOTE! We have to be ready to update the memory sharing
90  * between the file and the memory map for a potential last
91  * incomplete page.  Ugly, but necessary.
92  */
93 int vmtruncate(struct inode *inode, loff_t offset)
94 {
95         struct address_space *mapping = inode->i_mapping;
96         unsigned long limit;
97
98         if (inode->i_size < offset)
99                 goto do_expand;
100         i_size_write(inode, offset);
101
102         truncate_inode_pages(mapping, offset);
103         goto out_truncate;
104
105 do_expand:
106         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
107         if (limit != RLIM_INFINITY && offset > limit)
108                 goto out_sig;
109         if (offset > inode->i_sb->s_maxbytes)
110                 goto out;
111         i_size_write(inode, offset);
112
113 out_truncate:
114         if (inode->i_op->truncate)
115                 inode->i_op->truncate(inode);
116         return 0;
117 out_sig:
118         send_sig(SIGXFSZ, current, 0);
119 out:
120         return -EFBIG;
121 }
122
123 EXPORT_SYMBOL(vmtruncate);
124
125 /*
126  * Return the total memory allocated for this pointer, not
127  * just what the caller asked for.
128  *
129  * Doesn't have to be accurate, i.e. may have races.
130  */
131 unsigned int kobjsize(const void *objp)
132 {
133         struct page *page;
134
135         /*
136          * If the object we have should not have ksize performed on it,
137          * return size of 0
138          */
139         if (!objp || !virt_addr_valid(objp))
140                 return 0;
141
142         page = virt_to_head_page(objp);
143
144         /*
145          * If the allocator sets PageSlab, we know the pointer came from
146          * kmalloc().
147          */
148         if (PageSlab(page))
149                 return ksize(objp);
150
151         /*
152          * If it's not a compound page, see if we have a matching VMA
153          * region. This test is intentionally done in reverse order,
154          * so if there's no VMA, we still fall through and hand back
155          * PAGE_SIZE for 0-order pages.
156          */
157         if (!PageCompound(page)) {
158                 struct vm_area_struct *vma;
159
160                 vma = find_vma(current->mm, (unsigned long)objp);
161                 if (vma)
162                         return vma->vm_end - vma->vm_start;
163         }
164
165         /*
166          * The ksize() function is only guaranteed to work for pointers
167          * returned by kmalloc(). So handle arbitrary pointers here.
168          */
169         return PAGE_SIZE << compound_order(page);
170 }
171
172 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
173                      unsigned long start, int len, int flags,
174                 struct page **pages, struct vm_area_struct **vmas)
175 {
176         struct vm_area_struct *vma;
177         unsigned long vm_flags;
178         int i;
179         int write = !!(flags & GUP_FLAGS_WRITE);
180         int force = !!(flags & GUP_FLAGS_FORCE);
181         int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
182
183         /* calculate required read or write permissions.
184          * - if 'force' is set, we only require the "MAY" flags.
185          */
186         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
187         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
188
189         for (i = 0; i < len; i++) {
190                 vma = find_vma(mm, start);
191                 if (!vma)
192                         goto finish_or_fault;
193
194                 /* protect what we can, including chardevs */
195                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
196                     (!ignore && !(vm_flags & vma->vm_flags)))
197                         goto finish_or_fault;
198
199                 if (pages) {
200                         pages[i] = virt_to_page(start);
201                         if (pages[i])
202                                 page_cache_get(pages[i]);
203                 }
204                 if (vmas)
205                         vmas[i] = vma;
206                 start += PAGE_SIZE;
207         }
208
209         return i;
210
211 finish_or_fault:
212         return i ? : -EFAULT;
213 }
214
215
216 /*
217  * get a list of pages in an address range belonging to the specified process
218  * and indicate the VMA that covers each page
219  * - this is potentially dodgy as we may end incrementing the page count of a
220  *   slab page or a secondary page from a compound page
221  * - don't permit access to VMAs that don't support it, such as I/O mappings
222  */
223 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
224         unsigned long start, int len, int write, int force,
225         struct page **pages, struct vm_area_struct **vmas)
226 {
227         int flags = 0;
228
229         if (write)
230                 flags |= GUP_FLAGS_WRITE;
231         if (force)
232                 flags |= GUP_FLAGS_FORCE;
233
234         return __get_user_pages(tsk, mm,
235                                 start, len, flags,
236                                 pages, vmas);
237 }
238 EXPORT_SYMBOL(get_user_pages);
239
240 DEFINE_RWLOCK(vmlist_lock);
241 struct vm_struct *vmlist;
242
243 void vfree(const void *addr)
244 {
245         kfree(addr);
246 }
247 EXPORT_SYMBOL(vfree);
248
249 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
250 {
251         /*
252          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
253          * returns only a logical address.
254          */
255         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
256 }
257 EXPORT_SYMBOL(__vmalloc);
258
259 void *vmalloc_user(unsigned long size)
260 {
261         void *ret;
262
263         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
264                         PAGE_KERNEL);
265         if (ret) {
266                 struct vm_area_struct *vma;
267
268                 down_write(&current->mm->mmap_sem);
269                 vma = find_vma(current->mm, (unsigned long)ret);
270                 if (vma)
271                         vma->vm_flags |= VM_USERMAP;
272                 up_write(&current->mm->mmap_sem);
273         }
274
275         return ret;
276 }
277 EXPORT_SYMBOL(vmalloc_user);
278
279 struct page *vmalloc_to_page(const void *addr)
280 {
281         return virt_to_page(addr);
282 }
283 EXPORT_SYMBOL(vmalloc_to_page);
284
285 unsigned long vmalloc_to_pfn(const void *addr)
286 {
287         return page_to_pfn(virt_to_page(addr));
288 }
289 EXPORT_SYMBOL(vmalloc_to_pfn);
290
291 long vread(char *buf, char *addr, unsigned long count)
292 {
293         memcpy(buf, addr, count);
294         return count;
295 }
296
297 long vwrite(char *buf, char *addr, unsigned long count)
298 {
299         /* Don't allow overflow */
300         if ((unsigned long) addr + count < count)
301                 count = -(unsigned long) addr;
302
303         memcpy(addr, buf, count);
304         return(count);
305 }
306
307 /*
308  *      vmalloc  -  allocate virtually continguos memory
309  *
310  *      @size:          allocation size
311  *
312  *      Allocate enough pages to cover @size from the page level
313  *      allocator and map them into continguos kernel virtual space.
314  *
315  *      For tight control over page level allocator and protection flags
316  *      use __vmalloc() instead.
317  */
318 void *vmalloc(unsigned long size)
319 {
320        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
321 }
322 EXPORT_SYMBOL(vmalloc);
323
324 void *vmalloc_node(unsigned long size, int node)
325 {
326         return vmalloc(size);
327 }
328 EXPORT_SYMBOL(vmalloc_node);
329
330 #ifndef PAGE_KERNEL_EXEC
331 # define PAGE_KERNEL_EXEC PAGE_KERNEL
332 #endif
333
334 /**
335  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
336  *      @size:          allocation size
337  *
338  *      Kernel-internal function to allocate enough pages to cover @size
339  *      the page level allocator and map them into contiguous and
340  *      executable kernel virtual space.
341  *
342  *      For tight control over page level allocator and protection flags
343  *      use __vmalloc() instead.
344  */
345
346 void *vmalloc_exec(unsigned long size)
347 {
348         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
349 }
350
351 /**
352  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
353  *      @size:          allocation size
354  *
355  *      Allocate enough 32bit PA addressable pages to cover @size from the
356  *      page level allocator and map them into continguos kernel virtual space.
357  */
358 void *vmalloc_32(unsigned long size)
359 {
360         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
361 }
362 EXPORT_SYMBOL(vmalloc_32);
363
364 /**
365  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
366  *      @size:          allocation size
367  *
368  * The resulting memory area is 32bit addressable and zeroed so it can be
369  * mapped to userspace without leaking data.
370  *
371  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
372  * remap_vmalloc_range() are permissible.
373  */
374 void *vmalloc_32_user(unsigned long size)
375 {
376         /*
377          * We'll have to sort out the ZONE_DMA bits for 64-bit,
378          * but for now this can simply use vmalloc_user() directly.
379          */
380         return vmalloc_user(size);
381 }
382 EXPORT_SYMBOL(vmalloc_32_user);
383
384 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
385 {
386         BUG();
387         return NULL;
388 }
389 EXPORT_SYMBOL(vmap);
390
391 void vunmap(const void *addr)
392 {
393         BUG();
394 }
395 EXPORT_SYMBOL(vunmap);
396
397 /*
398  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
399  * have one.
400  */
401 void  __attribute__((weak)) vmalloc_sync_all(void)
402 {
403 }
404
405 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
406                    struct page *page)
407 {
408         return -EINVAL;
409 }
410 EXPORT_SYMBOL(vm_insert_page);
411
412 /*
413  *  sys_brk() for the most part doesn't need the global kernel
414  *  lock, except when an application is doing something nasty
415  *  like trying to un-brk an area that has already been mapped
416  *  to a regular file.  in this case, the unmapping will need
417  *  to invoke file system routines that need the global lock.
418  */
419 asmlinkage unsigned long sys_brk(unsigned long brk)
420 {
421         struct mm_struct *mm = current->mm;
422
423         if (brk < mm->start_brk || brk > mm->context.end_brk)
424                 return mm->brk;
425
426         if (mm->brk == brk)
427                 return mm->brk;
428
429         /*
430          * Always allow shrinking brk
431          */
432         if (brk <= mm->brk) {
433                 mm->brk = brk;
434                 return brk;
435         }
436
437         /*
438          * Ok, looks good - let it rip.
439          */
440         return mm->brk = brk;
441 }
442
443 /*
444  * initialise the VMA and region record slabs
445  */
446 void __init mmap_init(void)
447 {
448         vm_region_jar = kmem_cache_create("vm_region_jar",
449                                           sizeof(struct vm_region), 0,
450                                           SLAB_PANIC, NULL);
451         vm_area_cachep = kmem_cache_create("vm_area_struct",
452                                            sizeof(struct vm_area_struct), 0,
453                                            SLAB_PANIC, NULL);
454 }
455
456 /*
457  * validate the region tree
458  * - the caller must hold the region lock
459  */
460 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
461 static noinline void validate_nommu_regions(void)
462 {
463         struct vm_region *region, *last;
464         struct rb_node *p, *lastp;
465
466         lastp = rb_first(&nommu_region_tree);
467         if (!lastp)
468                 return;
469
470         last = rb_entry(lastp, struct vm_region, vm_rb);
471         if (unlikely(last->vm_end <= last->vm_start))
472                 BUG();
473         if (unlikely(last->vm_top < last->vm_end))
474                 BUG();
475
476         while ((p = rb_next(lastp))) {
477                 region = rb_entry(p, struct vm_region, vm_rb);
478                 last = rb_entry(lastp, struct vm_region, vm_rb);
479
480                 if (unlikely(region->vm_end <= region->vm_start))
481                         BUG();
482                 if (unlikely(region->vm_top < region->vm_end))
483                         BUG();
484                 if (unlikely(region->vm_start < last->vm_top))
485                         BUG();
486
487                 lastp = p;
488         }
489 }
490 #else
491 #define validate_nommu_regions() do {} while(0)
492 #endif
493
494 /*
495  * add a region into the global tree
496  */
497 static void add_nommu_region(struct vm_region *region)
498 {
499         struct vm_region *pregion;
500         struct rb_node **p, *parent;
501
502         validate_nommu_regions();
503
504         BUG_ON(region->vm_start & ~PAGE_MASK);
505
506         parent = NULL;
507         p = &nommu_region_tree.rb_node;
508         while (*p) {
509                 parent = *p;
510                 pregion = rb_entry(parent, struct vm_region, vm_rb);
511                 if (region->vm_start < pregion->vm_start)
512                         p = &(*p)->rb_left;
513                 else if (region->vm_start > pregion->vm_start)
514                         p = &(*p)->rb_right;
515                 else if (pregion == region)
516                         return;
517                 else
518                         BUG();
519         }
520
521         rb_link_node(&region->vm_rb, parent, p);
522         rb_insert_color(&region->vm_rb, &nommu_region_tree);
523
524         validate_nommu_regions();
525 }
526
527 /*
528  * delete a region from the global tree
529  */
530 static void delete_nommu_region(struct vm_region *region)
531 {
532         BUG_ON(!nommu_region_tree.rb_node);
533
534         validate_nommu_regions();
535         rb_erase(&region->vm_rb, &nommu_region_tree);
536         validate_nommu_regions();
537 }
538
539 /*
540  * free a contiguous series of pages
541  */
542 static void free_page_series(unsigned long from, unsigned long to)
543 {
544         for (; from < to; from += PAGE_SIZE) {
545                 struct page *page = virt_to_page(from);
546
547                 kdebug("- free %lx", from);
548                 atomic_dec(&mmap_pages_allocated);
549                 if (page_count(page) != 1)
550                         kdebug("free page %p [%d]", page, page_count(page));
551                 put_page(page);
552         }
553 }
554
555 /*
556  * release a reference to a region
557  * - the caller must hold the region semaphore, which this releases
558  * - the region may not have been added to the tree yet, in which case vm_top
559  *   will equal vm_start
560  */
561 static void __put_nommu_region(struct vm_region *region)
562         __releases(nommu_region_sem)
563 {
564         kenter("%p{%d}", region, atomic_read(&region->vm_usage));
565
566         BUG_ON(!nommu_region_tree.rb_node);
567
568         if (atomic_dec_and_test(&region->vm_usage)) {
569                 if (region->vm_top > region->vm_start)
570                         delete_nommu_region(region);
571                 up_write(&nommu_region_sem);
572
573                 if (region->vm_file)
574                         fput(region->vm_file);
575
576                 /* IO memory and memory shared directly out of the pagecache
577                  * from ramfs/tmpfs mustn't be released here */
578                 if (region->vm_flags & VM_MAPPED_COPY) {
579                         kdebug("free series");
580                         free_page_series(region->vm_start, region->vm_top);
581                 }
582                 kmem_cache_free(vm_region_jar, region);
583         } else {
584                 up_write(&nommu_region_sem);
585         }
586 }
587
588 /*
589  * release a reference to a region
590  */
591 static void put_nommu_region(struct vm_region *region)
592 {
593         down_write(&nommu_region_sem);
594         __put_nommu_region(region);
595 }
596
597 /*
598  * add a VMA into a process's mm_struct in the appropriate place in the list
599  * and tree and add to the address space's page tree also if not an anonymous
600  * page
601  * - should be called with mm->mmap_sem held writelocked
602  */
603 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
604 {
605         struct vm_area_struct *pvma, **pp;
606         struct address_space *mapping;
607         struct rb_node **p, *parent;
608
609         kenter(",%p", vma);
610
611         BUG_ON(!vma->vm_region);
612
613         mm->map_count++;
614         vma->vm_mm = mm;
615
616         /* add the VMA to the mapping */
617         if (vma->vm_file) {
618                 mapping = vma->vm_file->f_mapping;
619
620                 flush_dcache_mmap_lock(mapping);
621                 vma_prio_tree_insert(vma, &mapping->i_mmap);
622                 flush_dcache_mmap_unlock(mapping);
623         }
624
625         /* add the VMA to the tree */
626         parent = NULL;
627         p = &mm->mm_rb.rb_node;
628         while (*p) {
629                 parent = *p;
630                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
631
632                 /* sort by: start addr, end addr, VMA struct addr in that order
633                  * (the latter is necessary as we may get identical VMAs) */
634                 if (vma->vm_start < pvma->vm_start)
635                         p = &(*p)->rb_left;
636                 else if (vma->vm_start > pvma->vm_start)
637                         p = &(*p)->rb_right;
638                 else if (vma->vm_end < pvma->vm_end)
639                         p = &(*p)->rb_left;
640                 else if (vma->vm_end > pvma->vm_end)
641                         p = &(*p)->rb_right;
642                 else if (vma < pvma)
643                         p = &(*p)->rb_left;
644                 else if (vma > pvma)
645                         p = &(*p)->rb_right;
646                 else
647                         BUG();
648         }
649
650         rb_link_node(&vma->vm_rb, parent, p);
651         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
652
653         /* add VMA to the VMA list also */
654         for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
655                 if (pvma->vm_start > vma->vm_start)
656                         break;
657                 if (pvma->vm_start < vma->vm_start)
658                         continue;
659                 if (pvma->vm_end < vma->vm_end)
660                         break;
661         }
662
663         vma->vm_next = *pp;
664         *pp = vma;
665 }
666
667 /*
668  * delete a VMA from its owning mm_struct and address space
669  */
670 static void delete_vma_from_mm(struct vm_area_struct *vma)
671 {
672         struct vm_area_struct **pp;
673         struct address_space *mapping;
674         struct mm_struct *mm = vma->vm_mm;
675
676         kenter("%p", vma);
677
678         mm->map_count--;
679         if (mm->mmap_cache == vma)
680                 mm->mmap_cache = NULL;
681
682         /* remove the VMA from the mapping */
683         if (vma->vm_file) {
684                 mapping = vma->vm_file->f_mapping;
685
686                 flush_dcache_mmap_lock(mapping);
687                 vma_prio_tree_remove(vma, &mapping->i_mmap);
688                 flush_dcache_mmap_unlock(mapping);
689         }
690
691         /* remove from the MM's tree and list */
692         rb_erase(&vma->vm_rb, &mm->mm_rb);
693         for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
694                 if (*pp == vma) {
695                         *pp = vma->vm_next;
696                         break;
697                 }
698         }
699
700         vma->vm_mm = NULL;
701 }
702
703 /*
704  * destroy a VMA record
705  */
706 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
707 {
708         kenter("%p", vma);
709         if (vma->vm_ops && vma->vm_ops->close)
710                 vma->vm_ops->close(vma);
711         if (vma->vm_file) {
712                 fput(vma->vm_file);
713                 if (vma->vm_flags & VM_EXECUTABLE)
714                         removed_exe_file_vma(mm);
715         }
716         put_nommu_region(vma->vm_region);
717         kmem_cache_free(vm_area_cachep, vma);
718 }
719
720 /*
721  * look up the first VMA in which addr resides, NULL if none
722  * - should be called with mm->mmap_sem at least held readlocked
723  */
724 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
725 {
726         struct vm_area_struct *vma;
727         struct rb_node *n = mm->mm_rb.rb_node;
728
729         /* check the cache first */
730         vma = mm->mmap_cache;
731         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
732                 return vma;
733
734         /* trawl the tree (there may be multiple mappings in which addr
735          * resides) */
736         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
737                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
738                 if (vma->vm_start > addr)
739                         return NULL;
740                 if (vma->vm_end > addr) {
741                         mm->mmap_cache = vma;
742                         return vma;
743                 }
744         }
745
746         return NULL;
747 }
748 EXPORT_SYMBOL(find_vma);
749
750 /*
751  * find a VMA
752  * - we don't extend stack VMAs under NOMMU conditions
753  */
754 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
755 {
756         return find_vma(mm, addr);
757 }
758
759 /*
760  * expand a stack to a given address
761  * - not supported under NOMMU conditions
762  */
763 int expand_stack(struct vm_area_struct *vma, unsigned long address)
764 {
765         return -ENOMEM;
766 }
767
768 /*
769  * look up the first VMA exactly that exactly matches addr
770  * - should be called with mm->mmap_sem at least held readlocked
771  */
772 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
773                                              unsigned long addr,
774                                              unsigned long len)
775 {
776         struct vm_area_struct *vma;
777         struct rb_node *n = mm->mm_rb.rb_node;
778         unsigned long end = addr + len;
779
780         /* check the cache first */
781         vma = mm->mmap_cache;
782         if (vma && vma->vm_start == addr && vma->vm_end == end)
783                 return vma;
784
785         /* trawl the tree (there may be multiple mappings in which addr
786          * resides) */
787         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
788                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
789                 if (vma->vm_start < addr)
790                         continue;
791                 if (vma->vm_start > addr)
792                         return NULL;
793                 if (vma->vm_end == end) {
794                         mm->mmap_cache = vma;
795                         return vma;
796                 }
797         }
798
799         return NULL;
800 }
801
802 /*
803  * determine whether a mapping should be permitted and, if so, what sort of
804  * mapping we're capable of supporting
805  */
806 static int validate_mmap_request(struct file *file,
807                                  unsigned long addr,
808                                  unsigned long len,
809                                  unsigned long prot,
810                                  unsigned long flags,
811                                  unsigned long pgoff,
812                                  unsigned long *_capabilities)
813 {
814         unsigned long capabilities, rlen;
815         unsigned long reqprot = prot;
816         int ret;
817
818         /* do the simple checks first */
819         if (flags & MAP_FIXED || addr) {
820                 printk(KERN_DEBUG
821                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
822                        current->pid);
823                 return -EINVAL;
824         }
825
826         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
827             (flags & MAP_TYPE) != MAP_SHARED)
828                 return -EINVAL;
829
830         if (!len)
831                 return -EINVAL;
832
833         /* Careful about overflows.. */
834         rlen = PAGE_ALIGN(len);
835         if (!rlen || rlen > TASK_SIZE)
836                 return -ENOMEM;
837
838         /* offset overflow? */
839         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
840                 return -EOVERFLOW;
841
842         if (file) {
843                 /* validate file mapping requests */
844                 struct address_space *mapping;
845
846                 /* files must support mmap */
847                 if (!file->f_op || !file->f_op->mmap)
848                         return -ENODEV;
849
850                 /* work out if what we've got could possibly be shared
851                  * - we support chardevs that provide their own "memory"
852                  * - we support files/blockdevs that are memory backed
853                  */
854                 mapping = file->f_mapping;
855                 if (!mapping)
856                         mapping = file->f_path.dentry->d_inode->i_mapping;
857
858                 capabilities = 0;
859                 if (mapping && mapping->backing_dev_info)
860                         capabilities = mapping->backing_dev_info->capabilities;
861
862                 if (!capabilities) {
863                         /* no explicit capabilities set, so assume some
864                          * defaults */
865                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
866                         case S_IFREG:
867                         case S_IFBLK:
868                                 capabilities = BDI_CAP_MAP_COPY;
869                                 break;
870
871                         case S_IFCHR:
872                                 capabilities =
873                                         BDI_CAP_MAP_DIRECT |
874                                         BDI_CAP_READ_MAP |
875                                         BDI_CAP_WRITE_MAP;
876                                 break;
877
878                         default:
879                                 return -EINVAL;
880                         }
881                 }
882
883                 /* eliminate any capabilities that we can't support on this
884                  * device */
885                 if (!file->f_op->get_unmapped_area)
886                         capabilities &= ~BDI_CAP_MAP_DIRECT;
887                 if (!file->f_op->read)
888                         capabilities &= ~BDI_CAP_MAP_COPY;
889
890                 if (flags & MAP_SHARED) {
891                         /* do checks for writing, appending and locking */
892                         if ((prot & PROT_WRITE) &&
893                             !(file->f_mode & FMODE_WRITE))
894                                 return -EACCES;
895
896                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
897                             (file->f_mode & FMODE_WRITE))
898                                 return -EACCES;
899
900                         if (locks_verify_locked(file->f_path.dentry->d_inode))
901                                 return -EAGAIN;
902
903                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
904                                 return -ENODEV;
905
906                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
907                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
908                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
909                             ) {
910                                 printk("MAP_SHARED not completely supported on !MMU\n");
911                                 return -EINVAL;
912                         }
913
914                         /* we mustn't privatise shared mappings */
915                         capabilities &= ~BDI_CAP_MAP_COPY;
916                 }
917                 else {
918                         /* we're going to read the file into private memory we
919                          * allocate */
920                         if (!(capabilities & BDI_CAP_MAP_COPY))
921                                 return -ENODEV;
922
923                         /* we don't permit a private writable mapping to be
924                          * shared with the backing device */
925                         if (prot & PROT_WRITE)
926                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
927                 }
928
929                 /* handle executable mappings and implied executable
930                  * mappings */
931                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
932                         if (prot & PROT_EXEC)
933                                 return -EPERM;
934                 }
935                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
936                         /* handle implication of PROT_EXEC by PROT_READ */
937                         if (current->personality & READ_IMPLIES_EXEC) {
938                                 if (capabilities & BDI_CAP_EXEC_MAP)
939                                         prot |= PROT_EXEC;
940                         }
941                 }
942                 else if ((prot & PROT_READ) &&
943                          (prot & PROT_EXEC) &&
944                          !(capabilities & BDI_CAP_EXEC_MAP)
945                          ) {
946                         /* backing file is not executable, try to copy */
947                         capabilities &= ~BDI_CAP_MAP_DIRECT;
948                 }
949         }
950         else {
951                 /* anonymous mappings are always memory backed and can be
952                  * privately mapped
953                  */
954                 capabilities = BDI_CAP_MAP_COPY;
955
956                 /* handle PROT_EXEC implication by PROT_READ */
957                 if ((prot & PROT_READ) &&
958                     (current->personality & READ_IMPLIES_EXEC))
959                         prot |= PROT_EXEC;
960         }
961
962         /* allow the security API to have its say */
963         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
964         if (ret < 0)
965                 return ret;
966
967         /* looks okay */
968         *_capabilities = capabilities;
969         return 0;
970 }
971
972 /*
973  * we've determined that we can make the mapping, now translate what we
974  * now know into VMA flags
975  */
976 static unsigned long determine_vm_flags(struct file *file,
977                                         unsigned long prot,
978                                         unsigned long flags,
979                                         unsigned long capabilities)
980 {
981         unsigned long vm_flags;
982
983         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
984         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
985         /* vm_flags |= mm->def_flags; */
986
987         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
988                 /* attempt to share read-only copies of mapped file chunks */
989                 if (file && !(prot & PROT_WRITE))
990                         vm_flags |= VM_MAYSHARE;
991         }
992         else {
993                 /* overlay a shareable mapping on the backing device or inode
994                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
995                  * romfs/cramfs */
996                 if (flags & MAP_SHARED)
997                         vm_flags |= VM_MAYSHARE | VM_SHARED;
998                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
999                         vm_flags |= VM_MAYSHARE;
1000         }
1001
1002         /* refuse to let anyone share private mappings with this process if
1003          * it's being traced - otherwise breakpoints set in it may interfere
1004          * with another untraced process
1005          */
1006         if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1007                 vm_flags &= ~VM_MAYSHARE;
1008
1009         return vm_flags;
1010 }
1011
1012 /*
1013  * set up a shared mapping on a file (the driver or filesystem provides and
1014  * pins the storage)
1015  */
1016 static int do_mmap_shared_file(struct vm_area_struct *vma)
1017 {
1018         int ret;
1019
1020         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1021         if (ret == 0) {
1022                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1023                 return ret;
1024         }
1025         if (ret != -ENOSYS)
1026                 return ret;
1027
1028         /* getting an ENOSYS error indicates that direct mmap isn't
1029          * possible (as opposed to tried but failed) so we'll fall
1030          * through to making a private copy of the data and mapping
1031          * that if we can */
1032         return -ENODEV;
1033 }
1034
1035 /*
1036  * set up a private mapping or an anonymous shared mapping
1037  */
1038 static int do_mmap_private(struct vm_area_struct *vma,
1039                            struct vm_region *region,
1040                            unsigned long len)
1041 {
1042         struct page *pages;
1043         unsigned long total, point, n, rlen;
1044         void *base;
1045         int ret, order;
1046
1047         /* invoke the file's mapping function so that it can keep track of
1048          * shared mappings on devices or memory
1049          * - VM_MAYSHARE will be set if it may attempt to share
1050          */
1051         if (vma->vm_file) {
1052                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1053                 if (ret == 0) {
1054                         /* shouldn't return success if we're not sharing */
1055                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1056                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1057                         return ret;
1058                 }
1059                 if (ret != -ENOSYS)
1060                         return ret;
1061
1062                 /* getting an ENOSYS error indicates that direct mmap isn't
1063                  * possible (as opposed to tried but failed) so we'll try to
1064                  * make a private copy of the data and map that instead */
1065         }
1066
1067         rlen = PAGE_ALIGN(len);
1068
1069         /* allocate some memory to hold the mapping
1070          * - note that this may not return a page-aligned address if the object
1071          *   we're allocating is smaller than a page
1072          */
1073         order = get_order(rlen);
1074         kdebug("alloc order %d for %lx", order, len);
1075
1076         pages = alloc_pages(GFP_KERNEL, order);
1077         if (!pages)
1078                 goto enomem;
1079
1080         total = 1 << order;
1081         atomic_add(total, &mmap_pages_allocated);
1082
1083         point = rlen >> PAGE_SHIFT;
1084
1085         /* we allocated a power-of-2 sized page set, so we may want to trim off
1086          * the excess */
1087         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1088                 while (total > point) {
1089                         order = ilog2(total - point);
1090                         n = 1 << order;
1091                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1092                         atomic_sub(n, &mmap_pages_allocated);
1093                         total -= n;
1094                         set_page_refcounted(pages + total);
1095                         __free_pages(pages + total, order);
1096                 }
1097         }
1098
1099         for (point = 1; point < total; point++)
1100                 set_page_refcounted(&pages[point]);
1101
1102         base = page_address(pages);
1103         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1104         region->vm_start = (unsigned long) base;
1105         region->vm_end   = region->vm_start + rlen;
1106         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1107
1108         vma->vm_start = region->vm_start;
1109         vma->vm_end   = region->vm_start + len;
1110
1111         if (vma->vm_file) {
1112                 /* read the contents of a file into the copy */
1113                 mm_segment_t old_fs;
1114                 loff_t fpos;
1115
1116                 fpos = vma->vm_pgoff;
1117                 fpos <<= PAGE_SHIFT;
1118
1119                 old_fs = get_fs();
1120                 set_fs(KERNEL_DS);
1121                 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
1122                 set_fs(old_fs);
1123
1124                 if (ret < 0)
1125                         goto error_free;
1126
1127                 /* clear the last little bit */
1128                 if (ret < rlen)
1129                         memset(base + ret, 0, rlen - ret);
1130
1131         } else {
1132                 /* if it's an anonymous mapping, then just clear it */
1133                 memset(base, 0, rlen);
1134         }
1135
1136         return 0;
1137
1138 error_free:
1139         free_page_series(region->vm_start, region->vm_end);
1140         region->vm_start = vma->vm_start = 0;
1141         region->vm_end   = vma->vm_end = 0;
1142         region->vm_top   = 0;
1143         return ret;
1144
1145 enomem:
1146         printk("Allocation of length %lu from process %d failed\n",
1147                len, current->pid);
1148         show_free_areas();
1149         return -ENOMEM;
1150 }
1151
1152 /*
1153  * handle mapping creation for uClinux
1154  */
1155 unsigned long do_mmap_pgoff(struct file *file,
1156                             unsigned long addr,
1157                             unsigned long len,
1158                             unsigned long prot,
1159                             unsigned long flags,
1160                             unsigned long pgoff)
1161 {
1162         struct vm_area_struct *vma;
1163         struct vm_region *region;
1164         struct rb_node *rb;
1165         unsigned long capabilities, vm_flags, result;
1166         int ret;
1167
1168         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1169
1170         if (!(flags & MAP_FIXED))
1171                 addr = round_hint_to_min(addr);
1172
1173         /* decide whether we should attempt the mapping, and if so what sort of
1174          * mapping */
1175         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1176                                     &capabilities);
1177         if (ret < 0) {
1178                 kleave(" = %d [val]", ret);
1179                 return ret;
1180         }
1181
1182         /* we've determined that we can make the mapping, now translate what we
1183          * now know into VMA flags */
1184         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1185
1186         /* we're going to need to record the mapping */
1187         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1188         if (!region)
1189                 goto error_getting_region;
1190
1191         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1192         if (!vma)
1193                 goto error_getting_vma;
1194
1195         atomic_set(&region->vm_usage, 1);
1196         region->vm_flags = vm_flags;
1197         region->vm_pgoff = pgoff;
1198
1199         INIT_LIST_HEAD(&vma->anon_vma_node);
1200         vma->vm_flags = vm_flags;
1201         vma->vm_pgoff = pgoff;
1202
1203         if (file) {
1204                 region->vm_file = file;
1205                 get_file(file);
1206                 vma->vm_file = file;
1207                 get_file(file);
1208                 if (vm_flags & VM_EXECUTABLE) {
1209                         added_exe_file_vma(current->mm);
1210                         vma->vm_mm = current->mm;
1211                 }
1212         }
1213
1214         down_write(&nommu_region_sem);
1215
1216         /* if we want to share, we need to check for regions created by other
1217          * mmap() calls that overlap with our proposed mapping
1218          * - we can only share with a superset match on most regular files
1219          * - shared mappings on character devices and memory backed files are
1220          *   permitted to overlap inexactly as far as we are concerned for in
1221          *   these cases, sharing is handled in the driver or filesystem rather
1222          *   than here
1223          */
1224         if (vm_flags & VM_MAYSHARE) {
1225                 struct vm_region *pregion;
1226                 unsigned long pglen, rpglen, pgend, rpgend, start;
1227
1228                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1229                 pgend = pgoff + pglen;
1230
1231                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1232                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1233
1234                         if (!(pregion->vm_flags & VM_MAYSHARE))
1235                                 continue;
1236
1237                         /* search for overlapping mappings on the same file */
1238                         if (pregion->vm_file->f_path.dentry->d_inode !=
1239                             file->f_path.dentry->d_inode)
1240                                 continue;
1241
1242                         if (pregion->vm_pgoff >= pgend)
1243                                 continue;
1244
1245                         rpglen = pregion->vm_end - pregion->vm_start;
1246                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1247                         rpgend = pregion->vm_pgoff + rpglen;
1248                         if (pgoff >= rpgend)
1249                                 continue;
1250
1251                         /* handle inexactly overlapping matches between
1252                          * mappings */
1253                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1254                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1255                                 /* new mapping is not a subset of the region */
1256                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1257                                         goto sharing_violation;
1258                                 continue;
1259                         }
1260
1261                         /* we've found a region we can share */
1262                         atomic_inc(&pregion->vm_usage);
1263                         vma->vm_region = pregion;
1264                         start = pregion->vm_start;
1265                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1266                         vma->vm_start = start;
1267                         vma->vm_end = start + len;
1268
1269                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1270                                 kdebug("share copy");
1271                                 vma->vm_flags |= VM_MAPPED_COPY;
1272                         } else {
1273                                 kdebug("share mmap");
1274                                 ret = do_mmap_shared_file(vma);
1275                                 if (ret < 0) {
1276                                         vma->vm_region = NULL;
1277                                         vma->vm_start = 0;
1278                                         vma->vm_end = 0;
1279                                         atomic_dec(&pregion->vm_usage);
1280                                         pregion = NULL;
1281                                         goto error_just_free;
1282                                 }
1283                         }
1284                         fput(region->vm_file);
1285                         kmem_cache_free(vm_region_jar, region);
1286                         region = pregion;
1287                         result = start;
1288                         goto share;
1289                 }
1290
1291                 /* obtain the address at which to make a shared mapping
1292                  * - this is the hook for quasi-memory character devices to
1293                  *   tell us the location of a shared mapping
1294                  */
1295                 if (file && file->f_op->get_unmapped_area) {
1296                         addr = file->f_op->get_unmapped_area(file, addr, len,
1297                                                              pgoff, flags);
1298                         if (IS_ERR((void *) addr)) {
1299                                 ret = addr;
1300                                 if (ret != (unsigned long) -ENOSYS)
1301                                         goto error_just_free;
1302
1303                                 /* the driver refused to tell us where to site
1304                                  * the mapping so we'll have to attempt to copy
1305                                  * it */
1306                                 ret = (unsigned long) -ENODEV;
1307                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1308                                         goto error_just_free;
1309
1310                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1311                         } else {
1312                                 vma->vm_start = region->vm_start = addr;
1313                                 vma->vm_end = region->vm_end = addr + len;
1314                         }
1315                 }
1316         }
1317
1318         vma->vm_region = region;
1319
1320         /* set up the mapping */
1321         if (file && vma->vm_flags & VM_SHARED)
1322                 ret = do_mmap_shared_file(vma);
1323         else
1324                 ret = do_mmap_private(vma, region, len);
1325         if (ret < 0)
1326                 goto error_put_region;
1327
1328         add_nommu_region(region);
1329
1330         /* okay... we have a mapping; now we have to register it */
1331         result = vma->vm_start;
1332
1333         current->mm->total_vm += len >> PAGE_SHIFT;
1334
1335 share:
1336         add_vma_to_mm(current->mm, vma);
1337
1338         up_write(&nommu_region_sem);
1339
1340         if (prot & PROT_EXEC)
1341                 flush_icache_range(result, result + len);
1342
1343         kleave(" = %lx", result);
1344         return result;
1345
1346 error_put_region:
1347         __put_nommu_region(region);
1348         if (vma) {
1349                 if (vma->vm_file) {
1350                         fput(vma->vm_file);
1351                         if (vma->vm_flags & VM_EXECUTABLE)
1352                                 removed_exe_file_vma(vma->vm_mm);
1353                 }
1354                 kmem_cache_free(vm_area_cachep, vma);
1355         }
1356         kleave(" = %d [pr]", ret);
1357         return ret;
1358
1359 error_just_free:
1360         up_write(&nommu_region_sem);
1361 error:
1362         fput(region->vm_file);
1363         kmem_cache_free(vm_region_jar, region);
1364         fput(vma->vm_file);
1365         if (vma->vm_flags & VM_EXECUTABLE)
1366                 removed_exe_file_vma(vma->vm_mm);
1367         kmem_cache_free(vm_area_cachep, vma);
1368         kleave(" = %d", ret);
1369         return ret;
1370
1371 sharing_violation:
1372         up_write(&nommu_region_sem);
1373         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1374         ret = -EINVAL;
1375         goto error;
1376
1377 error_getting_vma:
1378         kmem_cache_free(vm_region_jar, region);
1379         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1380                " from process %d failed\n",
1381                len, current->pid);
1382         show_free_areas();
1383         return -ENOMEM;
1384
1385 error_getting_region:
1386         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1387                " from process %d failed\n",
1388                len, current->pid);
1389         show_free_areas();
1390         return -ENOMEM;
1391 }
1392 EXPORT_SYMBOL(do_mmap_pgoff);
1393
1394 /*
1395  * split a vma into two pieces at address 'addr', a new vma is allocated either
1396  * for the first part or the tail.
1397  */
1398 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1399               unsigned long addr, int new_below)
1400 {
1401         struct vm_area_struct *new;
1402         struct vm_region *region;
1403         unsigned long npages;
1404
1405         kenter("");
1406
1407         /* we're only permitted to split anonymous regions that have a single
1408          * owner */
1409         if (vma->vm_file ||
1410             atomic_read(&vma->vm_region->vm_usage) != 1)
1411                 return -ENOMEM;
1412
1413         if (mm->map_count >= sysctl_max_map_count)
1414                 return -ENOMEM;
1415
1416         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1417         if (!region)
1418                 return -ENOMEM;
1419
1420         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1421         if (!new) {
1422                 kmem_cache_free(vm_region_jar, region);
1423                 return -ENOMEM;
1424         }
1425
1426         /* most fields are the same, copy all, and then fixup */
1427         *new = *vma;
1428         *region = *vma->vm_region;
1429         new->vm_region = region;
1430
1431         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1432
1433         if (new_below) {
1434                 region->vm_top = region->vm_end = new->vm_end = addr;
1435         } else {
1436                 region->vm_start = new->vm_start = addr;
1437                 region->vm_pgoff = new->vm_pgoff += npages;
1438         }
1439
1440         if (new->vm_ops && new->vm_ops->open)
1441                 new->vm_ops->open(new);
1442
1443         delete_vma_from_mm(vma);
1444         down_write(&nommu_region_sem);
1445         delete_nommu_region(vma->vm_region);
1446         if (new_below) {
1447                 vma->vm_region->vm_start = vma->vm_start = addr;
1448                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1449         } else {
1450                 vma->vm_region->vm_end = vma->vm_end = addr;
1451                 vma->vm_region->vm_top = addr;
1452         }
1453         add_nommu_region(vma->vm_region);
1454         add_nommu_region(new->vm_region);
1455         up_write(&nommu_region_sem);
1456         add_vma_to_mm(mm, vma);
1457         add_vma_to_mm(mm, new);
1458         return 0;
1459 }
1460
1461 /*
1462  * shrink a VMA by removing the specified chunk from either the beginning or
1463  * the end
1464  */
1465 static int shrink_vma(struct mm_struct *mm,
1466                       struct vm_area_struct *vma,
1467                       unsigned long from, unsigned long to)
1468 {
1469         struct vm_region *region;
1470
1471         kenter("");
1472
1473         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1474          * and list */
1475         delete_vma_from_mm(vma);
1476         if (from > vma->vm_start)
1477                 vma->vm_end = from;
1478         else
1479                 vma->vm_start = to;
1480         add_vma_to_mm(mm, vma);
1481
1482         /* cut the backing region down to size */
1483         region = vma->vm_region;
1484         BUG_ON(atomic_read(&region->vm_usage) != 1);
1485
1486         down_write(&nommu_region_sem);
1487         delete_nommu_region(region);
1488         if (from > region->vm_start) {
1489                 to = region->vm_top;
1490                 region->vm_top = region->vm_end = from;
1491         } else {
1492                 region->vm_start = to;
1493         }
1494         add_nommu_region(region);
1495         up_write(&nommu_region_sem);
1496
1497         free_page_series(from, to);
1498         return 0;
1499 }
1500
1501 /*
1502  * release a mapping
1503  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1504  *   VMA, though it need not cover the whole VMA
1505  */
1506 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1507 {
1508         struct vm_area_struct *vma;
1509         struct rb_node *rb;
1510         unsigned long end = start + len;
1511         int ret;
1512
1513         kenter(",%lx,%zx", start, len);
1514
1515         if (len == 0)
1516                 return -EINVAL;
1517
1518         /* find the first potentially overlapping VMA */
1519         vma = find_vma(mm, start);
1520         if (!vma) {
1521                 printk(KERN_WARNING
1522                        "munmap of memory not mmapped by process %d (%s):"
1523                        " 0x%lx-0x%lx\n",
1524                        current->pid, current->comm, start, start + len - 1);
1525                 return -EINVAL;
1526         }
1527
1528         /* we're allowed to split an anonymous VMA but not a file-backed one */
1529         if (vma->vm_file) {
1530                 do {
1531                         if (start > vma->vm_start) {
1532                                 kleave(" = -EINVAL [miss]");
1533                                 return -EINVAL;
1534                         }
1535                         if (end == vma->vm_end)
1536                                 goto erase_whole_vma;
1537                         rb = rb_next(&vma->vm_rb);
1538                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1539                 } while (rb);
1540                 kleave(" = -EINVAL [split file]");
1541                 return -EINVAL;
1542         } else {
1543                 /* the chunk must be a subset of the VMA found */
1544                 if (start == vma->vm_start && end == vma->vm_end)
1545                         goto erase_whole_vma;
1546                 if (start < vma->vm_start || end > vma->vm_end) {
1547                         kleave(" = -EINVAL [superset]");
1548                         return -EINVAL;
1549                 }
1550                 if (start & ~PAGE_MASK) {
1551                         kleave(" = -EINVAL [unaligned start]");
1552                         return -EINVAL;
1553                 }
1554                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1555                         kleave(" = -EINVAL [unaligned split]");
1556                         return -EINVAL;
1557                 }
1558                 if (start != vma->vm_start && end != vma->vm_end) {
1559                         ret = split_vma(mm, vma, start, 1);
1560                         if (ret < 0) {
1561                                 kleave(" = %d [split]", ret);
1562                                 return ret;
1563                         }
1564                 }
1565                 return shrink_vma(mm, vma, start, end);
1566         }
1567
1568 erase_whole_vma:
1569         delete_vma_from_mm(vma);
1570         delete_vma(mm, vma);
1571         kleave(" = 0");
1572         return 0;
1573 }
1574 EXPORT_SYMBOL(do_munmap);
1575
1576 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1577 {
1578         int ret;
1579         struct mm_struct *mm = current->mm;
1580
1581         down_write(&mm->mmap_sem);
1582         ret = do_munmap(mm, addr, len);
1583         up_write(&mm->mmap_sem);
1584         return ret;
1585 }
1586
1587 /*
1588  * release all the mappings made in a process's VM space
1589  */
1590 void exit_mmap(struct mm_struct *mm)
1591 {
1592         struct vm_area_struct *vma;
1593
1594         if (!mm)
1595                 return;
1596
1597         kenter("");
1598
1599         mm->total_vm = 0;
1600
1601         while ((vma = mm->mmap)) {
1602                 mm->mmap = vma->vm_next;
1603                 delete_vma_from_mm(vma);
1604                 delete_vma(mm, vma);
1605         }
1606
1607         kleave("");
1608 }
1609
1610 unsigned long do_brk(unsigned long addr, unsigned long len)
1611 {
1612         return -ENOMEM;
1613 }
1614
1615 /*
1616  * expand (or shrink) an existing mapping, potentially moving it at the same
1617  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1618  *
1619  * under NOMMU conditions, we only permit changing a mapping's size, and only
1620  * as long as it stays within the region allocated by do_mmap_private() and the
1621  * block is not shareable
1622  *
1623  * MREMAP_FIXED is not supported under NOMMU conditions
1624  */
1625 unsigned long do_mremap(unsigned long addr,
1626                         unsigned long old_len, unsigned long new_len,
1627                         unsigned long flags, unsigned long new_addr)
1628 {
1629         struct vm_area_struct *vma;
1630
1631         /* insanity checks first */
1632         if (old_len == 0 || new_len == 0)
1633                 return (unsigned long) -EINVAL;
1634
1635         if (addr & ~PAGE_MASK)
1636                 return -EINVAL;
1637
1638         if (flags & MREMAP_FIXED && new_addr != addr)
1639                 return (unsigned long) -EINVAL;
1640
1641         vma = find_vma_exact(current->mm, addr, old_len);
1642         if (!vma)
1643                 return (unsigned long) -EINVAL;
1644
1645         if (vma->vm_end != vma->vm_start + old_len)
1646                 return (unsigned long) -EFAULT;
1647
1648         if (vma->vm_flags & VM_MAYSHARE)
1649                 return (unsigned long) -EPERM;
1650
1651         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1652                 return (unsigned long) -ENOMEM;
1653
1654         /* all checks complete - do it */
1655         vma->vm_end = vma->vm_start + new_len;
1656         return vma->vm_start;
1657 }
1658 EXPORT_SYMBOL(do_mremap);
1659
1660 asmlinkage
1661 unsigned long sys_mremap(unsigned long addr,
1662                          unsigned long old_len, unsigned long new_len,
1663                          unsigned long flags, unsigned long new_addr)
1664 {
1665         unsigned long ret;
1666
1667         down_write(&current->mm->mmap_sem);
1668         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1669         up_write(&current->mm->mmap_sem);
1670         return ret;
1671 }
1672
1673 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1674                         unsigned int foll_flags)
1675 {
1676         return NULL;
1677 }
1678
1679 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1680                 unsigned long to, unsigned long size, pgprot_t prot)
1681 {
1682         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1683         return 0;
1684 }
1685 EXPORT_SYMBOL(remap_pfn_range);
1686
1687 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1688                         unsigned long pgoff)
1689 {
1690         unsigned int size = vma->vm_end - vma->vm_start;
1691
1692         if (!(vma->vm_flags & VM_USERMAP))
1693                 return -EINVAL;
1694
1695         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1696         vma->vm_end = vma->vm_start + size;
1697
1698         return 0;
1699 }
1700 EXPORT_SYMBOL(remap_vmalloc_range);
1701
1702 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1703 {
1704 }
1705
1706 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1707         unsigned long len, unsigned long pgoff, unsigned long flags)
1708 {
1709         return -ENOMEM;
1710 }
1711
1712 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1713 {
1714 }
1715
1716 void unmap_mapping_range(struct address_space *mapping,
1717                          loff_t const holebegin, loff_t const holelen,
1718                          int even_cows)
1719 {
1720 }
1721 EXPORT_SYMBOL(unmap_mapping_range);
1722
1723 /*
1724  * ask for an unmapped area at which to create a mapping on a file
1725  */
1726 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1727                                 unsigned long len, unsigned long pgoff,
1728                                 unsigned long flags)
1729 {
1730         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1731                                   unsigned long, unsigned long);
1732
1733         get_area = current->mm->get_unmapped_area;
1734         if (file && file->f_op && file->f_op->get_unmapped_area)
1735                 get_area = file->f_op->get_unmapped_area;
1736
1737         if (!get_area)
1738                 return -ENOSYS;
1739
1740         return get_area(file, addr, len, pgoff, flags);
1741 }
1742 EXPORT_SYMBOL(get_unmapped_area);
1743
1744 /*
1745  * Check that a process has enough memory to allocate a new virtual
1746  * mapping. 0 means there is enough memory for the allocation to
1747  * succeed and -ENOMEM implies there is not.
1748  *
1749  * We currently support three overcommit policies, which are set via the
1750  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1751  *
1752  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1753  * Additional code 2002 Jul 20 by Robert Love.
1754  *
1755  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1756  *
1757  * Note this is a helper function intended to be used by LSMs which
1758  * wish to use this logic.
1759  */
1760 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1761 {
1762         unsigned long free, allowed;
1763
1764         vm_acct_memory(pages);
1765
1766         /*
1767          * Sometimes we want to use more memory than we have
1768          */
1769         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1770                 return 0;
1771
1772         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1773                 unsigned long n;
1774
1775                 free = global_page_state(NR_FILE_PAGES);
1776                 free += nr_swap_pages;
1777
1778                 /*
1779                  * Any slabs which are created with the
1780                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1781                  * which are reclaimable, under pressure.  The dentry
1782                  * cache and most inode caches should fall into this
1783                  */
1784                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1785
1786                 /*
1787                  * Leave the last 3% for root
1788                  */
1789                 if (!cap_sys_admin)
1790                         free -= free / 32;
1791
1792                 if (free > pages)
1793                         return 0;
1794
1795                 /*
1796                  * nr_free_pages() is very expensive on large systems,
1797                  * only call if we're about to fail.
1798                  */
1799                 n = nr_free_pages();
1800
1801                 /*
1802                  * Leave reserved pages. The pages are not for anonymous pages.
1803                  */
1804                 if (n <= totalreserve_pages)
1805                         goto error;
1806                 else
1807                         n -= totalreserve_pages;
1808
1809                 /*
1810                  * Leave the last 3% for root
1811                  */
1812                 if (!cap_sys_admin)
1813                         n -= n / 32;
1814                 free += n;
1815
1816                 if (free > pages)
1817                         return 0;
1818
1819                 goto error;
1820         }
1821
1822         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1823         /*
1824          * Leave the last 3% for root
1825          */
1826         if (!cap_sys_admin)
1827                 allowed -= allowed / 32;
1828         allowed += total_swap_pages;
1829
1830         /* Don't let a single process grow too big:
1831            leave 3% of the size of this process for other processes */
1832         if (mm)
1833                 allowed -= mm->total_vm / 32;
1834
1835         /*
1836          * cast `allowed' as a signed long because vm_committed_space
1837          * sometimes has a negative value
1838          */
1839         if (atomic_long_read(&vm_committed_space) < (long)allowed)
1840                 return 0;
1841 error:
1842         vm_unacct_memory(pages);
1843
1844         return -ENOMEM;
1845 }
1846
1847 int in_gate_area_no_task(unsigned long addr)
1848 {
1849         return 0;
1850 }
1851
1852 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1853 {
1854         BUG();
1855         return 0;
1856 }
1857 EXPORT_SYMBOL(filemap_fault);
1858
1859 /*
1860  * Access another process' address space.
1861  * - source/target buffer must be kernel space
1862  */
1863 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1864 {
1865         struct vm_area_struct *vma;
1866         struct mm_struct *mm;
1867
1868         if (addr + len < addr)
1869                 return 0;
1870
1871         mm = get_task_mm(tsk);
1872         if (!mm)
1873                 return 0;
1874
1875         down_read(&mm->mmap_sem);
1876
1877         /* the access must start within one of the target process's mappings */
1878         vma = find_vma(mm, addr);
1879         if (vma) {
1880                 /* don't overrun this mapping */
1881                 if (addr + len >= vma->vm_end)
1882                         len = vma->vm_end - addr;
1883
1884                 /* only read or write mappings where it is permitted */
1885                 if (write && vma->vm_flags & VM_MAYWRITE)
1886                         len -= copy_to_user((void *) addr, buf, len);
1887                 else if (!write && vma->vm_flags & VM_MAYREAD)
1888                         len -= copy_from_user(buf, (void *) addr, len);
1889                 else
1890                         len = 0;
1891         } else {
1892                 len = 0;
1893         }
1894
1895         up_read(&mm->mmap_sem);
1896         mmput(mm);
1897         return len;
1898 }