nommu: Stub in vm_map_ram()/vm_unmap_ram()/vm_unmap_aliases().
[linux-3.10.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) 2007-2009 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 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
398 {
399         BUG();
400         return NULL;
401 }
402 EXPORT_SYMBOL(vm_map_ram);
403
404 void vm_unmap_ram(const void *mem, unsigned int count)
405 {
406         BUG();
407 }
408 EXPORT_SYMBOL(vm_unmap_ram);
409
410 void vm_unmap_aliases(void)
411 {
412 }
413 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
414
415 /*
416  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
417  * have one.
418  */
419 void  __attribute__((weak)) vmalloc_sync_all(void)
420 {
421 }
422
423 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
424                    struct page *page)
425 {
426         return -EINVAL;
427 }
428 EXPORT_SYMBOL(vm_insert_page);
429
430 /*
431  *  sys_brk() for the most part doesn't need the global kernel
432  *  lock, except when an application is doing something nasty
433  *  like trying to un-brk an area that has already been mapped
434  *  to a regular file.  in this case, the unmapping will need
435  *  to invoke file system routines that need the global lock.
436  */
437 SYSCALL_DEFINE1(brk, unsigned long, brk)
438 {
439         struct mm_struct *mm = current->mm;
440
441         if (brk < mm->start_brk || brk > mm->context.end_brk)
442                 return mm->brk;
443
444         if (mm->brk == brk)
445                 return mm->brk;
446
447         /*
448          * Always allow shrinking brk
449          */
450         if (brk <= mm->brk) {
451                 mm->brk = brk;
452                 return brk;
453         }
454
455         /*
456          * Ok, looks good - let it rip.
457          */
458         return mm->brk = brk;
459 }
460
461 /*
462  * initialise the VMA and region record slabs
463  */
464 void __init mmap_init(void)
465 {
466         vm_region_jar = kmem_cache_create("vm_region_jar",
467                                           sizeof(struct vm_region), 0,
468                                           SLAB_PANIC, NULL);
469         vm_area_cachep = kmem_cache_create("vm_area_struct",
470                                            sizeof(struct vm_area_struct), 0,
471                                            SLAB_PANIC, NULL);
472 }
473
474 /*
475  * validate the region tree
476  * - the caller must hold the region lock
477  */
478 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
479 static noinline void validate_nommu_regions(void)
480 {
481         struct vm_region *region, *last;
482         struct rb_node *p, *lastp;
483
484         lastp = rb_first(&nommu_region_tree);
485         if (!lastp)
486                 return;
487
488         last = rb_entry(lastp, struct vm_region, vm_rb);
489         if (unlikely(last->vm_end <= last->vm_start))
490                 BUG();
491         if (unlikely(last->vm_top < last->vm_end))
492                 BUG();
493
494         while ((p = rb_next(lastp))) {
495                 region = rb_entry(p, struct vm_region, vm_rb);
496                 last = rb_entry(lastp, struct vm_region, vm_rb);
497
498                 if (unlikely(region->vm_end <= region->vm_start))
499                         BUG();
500                 if (unlikely(region->vm_top < region->vm_end))
501                         BUG();
502                 if (unlikely(region->vm_start < last->vm_top))
503                         BUG();
504
505                 lastp = p;
506         }
507 }
508 #else
509 #define validate_nommu_regions() do {} while(0)
510 #endif
511
512 /*
513  * add a region into the global tree
514  */
515 static void add_nommu_region(struct vm_region *region)
516 {
517         struct vm_region *pregion;
518         struct rb_node **p, *parent;
519
520         validate_nommu_regions();
521
522         BUG_ON(region->vm_start & ~PAGE_MASK);
523
524         parent = NULL;
525         p = &nommu_region_tree.rb_node;
526         while (*p) {
527                 parent = *p;
528                 pregion = rb_entry(parent, struct vm_region, vm_rb);
529                 if (region->vm_start < pregion->vm_start)
530                         p = &(*p)->rb_left;
531                 else if (region->vm_start > pregion->vm_start)
532                         p = &(*p)->rb_right;
533                 else if (pregion == region)
534                         return;
535                 else
536                         BUG();
537         }
538
539         rb_link_node(&region->vm_rb, parent, p);
540         rb_insert_color(&region->vm_rb, &nommu_region_tree);
541
542         validate_nommu_regions();
543 }
544
545 /*
546  * delete a region from the global tree
547  */
548 static void delete_nommu_region(struct vm_region *region)
549 {
550         BUG_ON(!nommu_region_tree.rb_node);
551
552         validate_nommu_regions();
553         rb_erase(&region->vm_rb, &nommu_region_tree);
554         validate_nommu_regions();
555 }
556
557 /*
558  * free a contiguous series of pages
559  */
560 static void free_page_series(unsigned long from, unsigned long to)
561 {
562         for (; from < to; from += PAGE_SIZE) {
563                 struct page *page = virt_to_page(from);
564
565                 kdebug("- free %lx", from);
566                 atomic_dec(&mmap_pages_allocated);
567                 if (page_count(page) != 1)
568                         kdebug("free page %p [%d]", page, page_count(page));
569                 put_page(page);
570         }
571 }
572
573 /*
574  * release a reference to a region
575  * - the caller must hold the region semaphore, which this releases
576  * - the region may not have been added to the tree yet, in which case vm_top
577  *   will equal vm_start
578  */
579 static void __put_nommu_region(struct vm_region *region)
580         __releases(nommu_region_sem)
581 {
582         kenter("%p{%d}", region, atomic_read(&region->vm_usage));
583
584         BUG_ON(!nommu_region_tree.rb_node);
585
586         if (atomic_dec_and_test(&region->vm_usage)) {
587                 if (region->vm_top > region->vm_start)
588                         delete_nommu_region(region);
589                 up_write(&nommu_region_sem);
590
591                 if (region->vm_file)
592                         fput(region->vm_file);
593
594                 /* IO memory and memory shared directly out of the pagecache
595                  * from ramfs/tmpfs mustn't be released here */
596                 if (region->vm_flags & VM_MAPPED_COPY) {
597                         kdebug("free series");
598                         free_page_series(region->vm_start, region->vm_top);
599                 }
600                 kmem_cache_free(vm_region_jar, region);
601         } else {
602                 up_write(&nommu_region_sem);
603         }
604 }
605
606 /*
607  * release a reference to a region
608  */
609 static void put_nommu_region(struct vm_region *region)
610 {
611         down_write(&nommu_region_sem);
612         __put_nommu_region(region);
613 }
614
615 /*
616  * add a VMA into a process's mm_struct in the appropriate place in the list
617  * and tree and add to the address space's page tree also if not an anonymous
618  * page
619  * - should be called with mm->mmap_sem held writelocked
620  */
621 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
622 {
623         struct vm_area_struct *pvma, **pp;
624         struct address_space *mapping;
625         struct rb_node **p, *parent;
626
627         kenter(",%p", vma);
628
629         BUG_ON(!vma->vm_region);
630
631         mm->map_count++;
632         vma->vm_mm = mm;
633
634         /* add the VMA to the mapping */
635         if (vma->vm_file) {
636                 mapping = vma->vm_file->f_mapping;
637
638                 flush_dcache_mmap_lock(mapping);
639                 vma_prio_tree_insert(vma, &mapping->i_mmap);
640                 flush_dcache_mmap_unlock(mapping);
641         }
642
643         /* add the VMA to the tree */
644         parent = NULL;
645         p = &mm->mm_rb.rb_node;
646         while (*p) {
647                 parent = *p;
648                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
649
650                 /* sort by: start addr, end addr, VMA struct addr in that order
651                  * (the latter is necessary as we may get identical VMAs) */
652                 if (vma->vm_start < pvma->vm_start)
653                         p = &(*p)->rb_left;
654                 else if (vma->vm_start > pvma->vm_start)
655                         p = &(*p)->rb_right;
656                 else if (vma->vm_end < pvma->vm_end)
657                         p = &(*p)->rb_left;
658                 else if (vma->vm_end > pvma->vm_end)
659                         p = &(*p)->rb_right;
660                 else if (vma < pvma)
661                         p = &(*p)->rb_left;
662                 else if (vma > pvma)
663                         p = &(*p)->rb_right;
664                 else
665                         BUG();
666         }
667
668         rb_link_node(&vma->vm_rb, parent, p);
669         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
670
671         /* add VMA to the VMA list also */
672         for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
673                 if (pvma->vm_start > vma->vm_start)
674                         break;
675                 if (pvma->vm_start < vma->vm_start)
676                         continue;
677                 if (pvma->vm_end < vma->vm_end)
678                         break;
679         }
680
681         vma->vm_next = *pp;
682         *pp = vma;
683 }
684
685 /*
686  * delete a VMA from its owning mm_struct and address space
687  */
688 static void delete_vma_from_mm(struct vm_area_struct *vma)
689 {
690         struct vm_area_struct **pp;
691         struct address_space *mapping;
692         struct mm_struct *mm = vma->vm_mm;
693
694         kenter("%p", vma);
695
696         mm->map_count--;
697         if (mm->mmap_cache == vma)
698                 mm->mmap_cache = NULL;
699
700         /* remove the VMA from the mapping */
701         if (vma->vm_file) {
702                 mapping = vma->vm_file->f_mapping;
703
704                 flush_dcache_mmap_lock(mapping);
705                 vma_prio_tree_remove(vma, &mapping->i_mmap);
706                 flush_dcache_mmap_unlock(mapping);
707         }
708
709         /* remove from the MM's tree and list */
710         rb_erase(&vma->vm_rb, &mm->mm_rb);
711         for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
712                 if (*pp == vma) {
713                         *pp = vma->vm_next;
714                         break;
715                 }
716         }
717
718         vma->vm_mm = NULL;
719 }
720
721 /*
722  * destroy a VMA record
723  */
724 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
725 {
726         kenter("%p", vma);
727         if (vma->vm_ops && vma->vm_ops->close)
728                 vma->vm_ops->close(vma);
729         if (vma->vm_file) {
730                 fput(vma->vm_file);
731                 if (vma->vm_flags & VM_EXECUTABLE)
732                         removed_exe_file_vma(mm);
733         }
734         put_nommu_region(vma->vm_region);
735         kmem_cache_free(vm_area_cachep, vma);
736 }
737
738 /*
739  * look up the first VMA in which addr resides, NULL if none
740  * - should be called with mm->mmap_sem at least held readlocked
741  */
742 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
743 {
744         struct vm_area_struct *vma;
745         struct rb_node *n = mm->mm_rb.rb_node;
746
747         /* check the cache first */
748         vma = mm->mmap_cache;
749         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
750                 return vma;
751
752         /* trawl the tree (there may be multiple mappings in which addr
753          * resides) */
754         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
755                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
756                 if (vma->vm_start > addr)
757                         return NULL;
758                 if (vma->vm_end > addr) {
759                         mm->mmap_cache = vma;
760                         return vma;
761                 }
762         }
763
764         return NULL;
765 }
766 EXPORT_SYMBOL(find_vma);
767
768 /*
769  * find a VMA
770  * - we don't extend stack VMAs under NOMMU conditions
771  */
772 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
773 {
774         return find_vma(mm, addr);
775 }
776
777 /*
778  * expand a stack to a given address
779  * - not supported under NOMMU conditions
780  */
781 int expand_stack(struct vm_area_struct *vma, unsigned long address)
782 {
783         return -ENOMEM;
784 }
785
786 /*
787  * look up the first VMA exactly that exactly matches addr
788  * - should be called with mm->mmap_sem at least held readlocked
789  */
790 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
791                                              unsigned long addr,
792                                              unsigned long len)
793 {
794         struct vm_area_struct *vma;
795         struct rb_node *n = mm->mm_rb.rb_node;
796         unsigned long end = addr + len;
797
798         /* check the cache first */
799         vma = mm->mmap_cache;
800         if (vma && vma->vm_start == addr && vma->vm_end == end)
801                 return vma;
802
803         /* trawl the tree (there may be multiple mappings in which addr
804          * resides) */
805         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
806                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
807                 if (vma->vm_start < addr)
808                         continue;
809                 if (vma->vm_start > addr)
810                         return NULL;
811                 if (vma->vm_end == end) {
812                         mm->mmap_cache = vma;
813                         return vma;
814                 }
815         }
816
817         return NULL;
818 }
819
820 /*
821  * determine whether a mapping should be permitted and, if so, what sort of
822  * mapping we're capable of supporting
823  */
824 static int validate_mmap_request(struct file *file,
825                                  unsigned long addr,
826                                  unsigned long len,
827                                  unsigned long prot,
828                                  unsigned long flags,
829                                  unsigned long pgoff,
830                                  unsigned long *_capabilities)
831 {
832         unsigned long capabilities, rlen;
833         unsigned long reqprot = prot;
834         int ret;
835
836         /* do the simple checks first */
837         if (flags & MAP_FIXED || addr) {
838                 printk(KERN_DEBUG
839                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
840                        current->pid);
841                 return -EINVAL;
842         }
843
844         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
845             (flags & MAP_TYPE) != MAP_SHARED)
846                 return -EINVAL;
847
848         if (!len)
849                 return -EINVAL;
850
851         /* Careful about overflows.. */
852         rlen = PAGE_ALIGN(len);
853         if (!rlen || rlen > TASK_SIZE)
854                 return -ENOMEM;
855
856         /* offset overflow? */
857         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
858                 return -EOVERFLOW;
859
860         if (file) {
861                 /* validate file mapping requests */
862                 struct address_space *mapping;
863
864                 /* files must support mmap */
865                 if (!file->f_op || !file->f_op->mmap)
866                         return -ENODEV;
867
868                 /* work out if what we've got could possibly be shared
869                  * - we support chardevs that provide their own "memory"
870                  * - we support files/blockdevs that are memory backed
871                  */
872                 mapping = file->f_mapping;
873                 if (!mapping)
874                         mapping = file->f_path.dentry->d_inode->i_mapping;
875
876                 capabilities = 0;
877                 if (mapping && mapping->backing_dev_info)
878                         capabilities = mapping->backing_dev_info->capabilities;
879
880                 if (!capabilities) {
881                         /* no explicit capabilities set, so assume some
882                          * defaults */
883                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
884                         case S_IFREG:
885                         case S_IFBLK:
886                                 capabilities = BDI_CAP_MAP_COPY;
887                                 break;
888
889                         case S_IFCHR:
890                                 capabilities =
891                                         BDI_CAP_MAP_DIRECT |
892                                         BDI_CAP_READ_MAP |
893                                         BDI_CAP_WRITE_MAP;
894                                 break;
895
896                         default:
897                                 return -EINVAL;
898                         }
899                 }
900
901                 /* eliminate any capabilities that we can't support on this
902                  * device */
903                 if (!file->f_op->get_unmapped_area)
904                         capabilities &= ~BDI_CAP_MAP_DIRECT;
905                 if (!file->f_op->read)
906                         capabilities &= ~BDI_CAP_MAP_COPY;
907
908                 if (flags & MAP_SHARED) {
909                         /* do checks for writing, appending and locking */
910                         if ((prot & PROT_WRITE) &&
911                             !(file->f_mode & FMODE_WRITE))
912                                 return -EACCES;
913
914                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
915                             (file->f_mode & FMODE_WRITE))
916                                 return -EACCES;
917
918                         if (locks_verify_locked(file->f_path.dentry->d_inode))
919                                 return -EAGAIN;
920
921                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
922                                 return -ENODEV;
923
924                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
925                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
926                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
927                             ) {
928                                 printk("MAP_SHARED not completely supported on !MMU\n");
929                                 return -EINVAL;
930                         }
931
932                         /* we mustn't privatise shared mappings */
933                         capabilities &= ~BDI_CAP_MAP_COPY;
934                 }
935                 else {
936                         /* we're going to read the file into private memory we
937                          * allocate */
938                         if (!(capabilities & BDI_CAP_MAP_COPY))
939                                 return -ENODEV;
940
941                         /* we don't permit a private writable mapping to be
942                          * shared with the backing device */
943                         if (prot & PROT_WRITE)
944                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
945                 }
946
947                 /* handle executable mappings and implied executable
948                  * mappings */
949                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
950                         if (prot & PROT_EXEC)
951                                 return -EPERM;
952                 }
953                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
954                         /* handle implication of PROT_EXEC by PROT_READ */
955                         if (current->personality & READ_IMPLIES_EXEC) {
956                                 if (capabilities & BDI_CAP_EXEC_MAP)
957                                         prot |= PROT_EXEC;
958                         }
959                 }
960                 else if ((prot & PROT_READ) &&
961                          (prot & PROT_EXEC) &&
962                          !(capabilities & BDI_CAP_EXEC_MAP)
963                          ) {
964                         /* backing file is not executable, try to copy */
965                         capabilities &= ~BDI_CAP_MAP_DIRECT;
966                 }
967         }
968         else {
969                 /* anonymous mappings are always memory backed and can be
970                  * privately mapped
971                  */
972                 capabilities = BDI_CAP_MAP_COPY;
973
974                 /* handle PROT_EXEC implication by PROT_READ */
975                 if ((prot & PROT_READ) &&
976                     (current->personality & READ_IMPLIES_EXEC))
977                         prot |= PROT_EXEC;
978         }
979
980         /* allow the security API to have its say */
981         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
982         if (ret < 0)
983                 return ret;
984
985         /* looks okay */
986         *_capabilities = capabilities;
987         return 0;
988 }
989
990 /*
991  * we've determined that we can make the mapping, now translate what we
992  * now know into VMA flags
993  */
994 static unsigned long determine_vm_flags(struct file *file,
995                                         unsigned long prot,
996                                         unsigned long flags,
997                                         unsigned long capabilities)
998 {
999         unsigned long vm_flags;
1000
1001         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1002         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1003         /* vm_flags |= mm->def_flags; */
1004
1005         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1006                 /* attempt to share read-only copies of mapped file chunks */
1007                 if (file && !(prot & PROT_WRITE))
1008                         vm_flags |= VM_MAYSHARE;
1009         }
1010         else {
1011                 /* overlay a shareable mapping on the backing device or inode
1012                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1013                  * romfs/cramfs */
1014                 if (flags & MAP_SHARED)
1015                         vm_flags |= VM_MAYSHARE | VM_SHARED;
1016                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
1017                         vm_flags |= VM_MAYSHARE;
1018         }
1019
1020         /* refuse to let anyone share private mappings with this process if
1021          * it's being traced - otherwise breakpoints set in it may interfere
1022          * with another untraced process
1023          */
1024         if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1025                 vm_flags &= ~VM_MAYSHARE;
1026
1027         return vm_flags;
1028 }
1029
1030 /*
1031  * set up a shared mapping on a file (the driver or filesystem provides and
1032  * pins the storage)
1033  */
1034 static int do_mmap_shared_file(struct vm_area_struct *vma)
1035 {
1036         int ret;
1037
1038         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1039         if (ret == 0) {
1040                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1041                 return ret;
1042         }
1043         if (ret != -ENOSYS)
1044                 return ret;
1045
1046         /* getting an ENOSYS error indicates that direct mmap isn't
1047          * possible (as opposed to tried but failed) so we'll fall
1048          * through to making a private copy of the data and mapping
1049          * that if we can */
1050         return -ENODEV;
1051 }
1052
1053 /*
1054  * set up a private mapping or an anonymous shared mapping
1055  */
1056 static int do_mmap_private(struct vm_area_struct *vma,
1057                            struct vm_region *region,
1058                            unsigned long len)
1059 {
1060         struct page *pages;
1061         unsigned long total, point, n, rlen;
1062         void *base;
1063         int ret, order;
1064
1065         /* invoke the file's mapping function so that it can keep track of
1066          * shared mappings on devices or memory
1067          * - VM_MAYSHARE will be set if it may attempt to share
1068          */
1069         if (vma->vm_file) {
1070                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1071                 if (ret == 0) {
1072                         /* shouldn't return success if we're not sharing */
1073                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1074                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1075                         return ret;
1076                 }
1077                 if (ret != -ENOSYS)
1078                         return ret;
1079
1080                 /* getting an ENOSYS error indicates that direct mmap isn't
1081                  * possible (as opposed to tried but failed) so we'll try to
1082                  * make a private copy of the data and map that instead */
1083         }
1084
1085         rlen = PAGE_ALIGN(len);
1086
1087         /* allocate some memory to hold the mapping
1088          * - note that this may not return a page-aligned address if the object
1089          *   we're allocating is smaller than a page
1090          */
1091         order = get_order(rlen);
1092         kdebug("alloc order %d for %lx", order, len);
1093
1094         pages = alloc_pages(GFP_KERNEL, order);
1095         if (!pages)
1096                 goto enomem;
1097
1098         total = 1 << order;
1099         atomic_add(total, &mmap_pages_allocated);
1100
1101         point = rlen >> PAGE_SHIFT;
1102
1103         /* we allocated a power-of-2 sized page set, so we may want to trim off
1104          * the excess */
1105         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1106                 while (total > point) {
1107                         order = ilog2(total - point);
1108                         n = 1 << order;
1109                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1110                         atomic_sub(n, &mmap_pages_allocated);
1111                         total -= n;
1112                         set_page_refcounted(pages + total);
1113                         __free_pages(pages + total, order);
1114                 }
1115         }
1116
1117         for (point = 1; point < total; point++)
1118                 set_page_refcounted(&pages[point]);
1119
1120         base = page_address(pages);
1121         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1122         region->vm_start = (unsigned long) base;
1123         region->vm_end   = region->vm_start + rlen;
1124         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1125
1126         vma->vm_start = region->vm_start;
1127         vma->vm_end   = region->vm_start + len;
1128
1129         if (vma->vm_file) {
1130                 /* read the contents of a file into the copy */
1131                 mm_segment_t old_fs;
1132                 loff_t fpos;
1133
1134                 fpos = vma->vm_pgoff;
1135                 fpos <<= PAGE_SHIFT;
1136
1137                 old_fs = get_fs();
1138                 set_fs(KERNEL_DS);
1139                 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
1140                 set_fs(old_fs);
1141
1142                 if (ret < 0)
1143                         goto error_free;
1144
1145                 /* clear the last little bit */
1146                 if (ret < rlen)
1147                         memset(base + ret, 0, rlen - ret);
1148
1149         } else {
1150                 /* if it's an anonymous mapping, then just clear it */
1151                 memset(base, 0, rlen);
1152         }
1153
1154         return 0;
1155
1156 error_free:
1157         free_page_series(region->vm_start, region->vm_end);
1158         region->vm_start = vma->vm_start = 0;
1159         region->vm_end   = vma->vm_end = 0;
1160         region->vm_top   = 0;
1161         return ret;
1162
1163 enomem:
1164         printk("Allocation of length %lu from process %d failed\n",
1165                len, current->pid);
1166         show_free_areas();
1167         return -ENOMEM;
1168 }
1169
1170 /*
1171  * handle mapping creation for uClinux
1172  */
1173 unsigned long do_mmap_pgoff(struct file *file,
1174                             unsigned long addr,
1175                             unsigned long len,
1176                             unsigned long prot,
1177                             unsigned long flags,
1178                             unsigned long pgoff)
1179 {
1180         struct vm_area_struct *vma;
1181         struct vm_region *region;
1182         struct rb_node *rb;
1183         unsigned long capabilities, vm_flags, result;
1184         int ret;
1185
1186         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1187
1188         if (!(flags & MAP_FIXED))
1189                 addr = round_hint_to_min(addr);
1190
1191         /* decide whether we should attempt the mapping, and if so what sort of
1192          * mapping */
1193         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1194                                     &capabilities);
1195         if (ret < 0) {
1196                 kleave(" = %d [val]", ret);
1197                 return ret;
1198         }
1199
1200         /* we've determined that we can make the mapping, now translate what we
1201          * now know into VMA flags */
1202         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1203
1204         /* we're going to need to record the mapping */
1205         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1206         if (!region)
1207                 goto error_getting_region;
1208
1209         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1210         if (!vma)
1211                 goto error_getting_vma;
1212
1213         atomic_set(&region->vm_usage, 1);
1214         region->vm_flags = vm_flags;
1215         region->vm_pgoff = pgoff;
1216
1217         INIT_LIST_HEAD(&vma->anon_vma_node);
1218         vma->vm_flags = vm_flags;
1219         vma->vm_pgoff = pgoff;
1220
1221         if (file) {
1222                 region->vm_file = file;
1223                 get_file(file);
1224                 vma->vm_file = file;
1225                 get_file(file);
1226                 if (vm_flags & VM_EXECUTABLE) {
1227                         added_exe_file_vma(current->mm);
1228                         vma->vm_mm = current->mm;
1229                 }
1230         }
1231
1232         down_write(&nommu_region_sem);
1233
1234         /* if we want to share, we need to check for regions created by other
1235          * mmap() calls that overlap with our proposed mapping
1236          * - we can only share with a superset match on most regular files
1237          * - shared mappings on character devices and memory backed files are
1238          *   permitted to overlap inexactly as far as we are concerned for in
1239          *   these cases, sharing is handled in the driver or filesystem rather
1240          *   than here
1241          */
1242         if (vm_flags & VM_MAYSHARE) {
1243                 struct vm_region *pregion;
1244                 unsigned long pglen, rpglen, pgend, rpgend, start;
1245
1246                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1247                 pgend = pgoff + pglen;
1248
1249                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1250                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1251
1252                         if (!(pregion->vm_flags & VM_MAYSHARE))
1253                                 continue;
1254
1255                         /* search for overlapping mappings on the same file */
1256                         if (pregion->vm_file->f_path.dentry->d_inode !=
1257                             file->f_path.dentry->d_inode)
1258                                 continue;
1259
1260                         if (pregion->vm_pgoff >= pgend)
1261                                 continue;
1262
1263                         rpglen = pregion->vm_end - pregion->vm_start;
1264                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1265                         rpgend = pregion->vm_pgoff + rpglen;
1266                         if (pgoff >= rpgend)
1267                                 continue;
1268
1269                         /* handle inexactly overlapping matches between
1270                          * mappings */
1271                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1272                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1273                                 /* new mapping is not a subset of the region */
1274                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1275                                         goto sharing_violation;
1276                                 continue;
1277                         }
1278
1279                         /* we've found a region we can share */
1280                         atomic_inc(&pregion->vm_usage);
1281                         vma->vm_region = pregion;
1282                         start = pregion->vm_start;
1283                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1284                         vma->vm_start = start;
1285                         vma->vm_end = start + len;
1286
1287                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1288                                 kdebug("share copy");
1289                                 vma->vm_flags |= VM_MAPPED_COPY;
1290                         } else {
1291                                 kdebug("share mmap");
1292                                 ret = do_mmap_shared_file(vma);
1293                                 if (ret < 0) {
1294                                         vma->vm_region = NULL;
1295                                         vma->vm_start = 0;
1296                                         vma->vm_end = 0;
1297                                         atomic_dec(&pregion->vm_usage);
1298                                         pregion = NULL;
1299                                         goto error_just_free;
1300                                 }
1301                         }
1302                         fput(region->vm_file);
1303                         kmem_cache_free(vm_region_jar, region);
1304                         region = pregion;
1305                         result = start;
1306                         goto share;
1307                 }
1308
1309                 /* obtain the address at which to make a shared mapping
1310                  * - this is the hook for quasi-memory character devices to
1311                  *   tell us the location of a shared mapping
1312                  */
1313                 if (file && file->f_op->get_unmapped_area) {
1314                         addr = file->f_op->get_unmapped_area(file, addr, len,
1315                                                              pgoff, flags);
1316                         if (IS_ERR((void *) addr)) {
1317                                 ret = addr;
1318                                 if (ret != (unsigned long) -ENOSYS)
1319                                         goto error_just_free;
1320
1321                                 /* the driver refused to tell us where to site
1322                                  * the mapping so we'll have to attempt to copy
1323                                  * it */
1324                                 ret = (unsigned long) -ENODEV;
1325                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1326                                         goto error_just_free;
1327
1328                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1329                         } else {
1330                                 vma->vm_start = region->vm_start = addr;
1331                                 vma->vm_end = region->vm_end = addr + len;
1332                         }
1333                 }
1334         }
1335
1336         vma->vm_region = region;
1337
1338         /* set up the mapping */
1339         if (file && vma->vm_flags & VM_SHARED)
1340                 ret = do_mmap_shared_file(vma);
1341         else
1342                 ret = do_mmap_private(vma, region, len);
1343         if (ret < 0)
1344                 goto error_put_region;
1345
1346         add_nommu_region(region);
1347
1348         /* okay... we have a mapping; now we have to register it */
1349         result = vma->vm_start;
1350
1351         current->mm->total_vm += len >> PAGE_SHIFT;
1352
1353 share:
1354         add_vma_to_mm(current->mm, vma);
1355
1356         up_write(&nommu_region_sem);
1357
1358         if (prot & PROT_EXEC)
1359                 flush_icache_range(result, result + len);
1360
1361         kleave(" = %lx", result);
1362         return result;
1363
1364 error_put_region:
1365         __put_nommu_region(region);
1366         if (vma) {
1367                 if (vma->vm_file) {
1368                         fput(vma->vm_file);
1369                         if (vma->vm_flags & VM_EXECUTABLE)
1370                                 removed_exe_file_vma(vma->vm_mm);
1371                 }
1372                 kmem_cache_free(vm_area_cachep, vma);
1373         }
1374         kleave(" = %d [pr]", ret);
1375         return ret;
1376
1377 error_just_free:
1378         up_write(&nommu_region_sem);
1379 error:
1380         fput(region->vm_file);
1381         kmem_cache_free(vm_region_jar, region);
1382         fput(vma->vm_file);
1383         if (vma->vm_flags & VM_EXECUTABLE)
1384                 removed_exe_file_vma(vma->vm_mm);
1385         kmem_cache_free(vm_area_cachep, vma);
1386         kleave(" = %d", ret);
1387         return ret;
1388
1389 sharing_violation:
1390         up_write(&nommu_region_sem);
1391         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1392         ret = -EINVAL;
1393         goto error;
1394
1395 error_getting_vma:
1396         kmem_cache_free(vm_region_jar, region);
1397         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1398                " from process %d failed\n",
1399                len, current->pid);
1400         show_free_areas();
1401         return -ENOMEM;
1402
1403 error_getting_region:
1404         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1405                " from process %d failed\n",
1406                len, current->pid);
1407         show_free_areas();
1408         return -ENOMEM;
1409 }
1410 EXPORT_SYMBOL(do_mmap_pgoff);
1411
1412 /*
1413  * split a vma into two pieces at address 'addr', a new vma is allocated either
1414  * for the first part or the tail.
1415  */
1416 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1417               unsigned long addr, int new_below)
1418 {
1419         struct vm_area_struct *new;
1420         struct vm_region *region;
1421         unsigned long npages;
1422
1423         kenter("");
1424
1425         /* we're only permitted to split anonymous regions that have a single
1426          * owner */
1427         if (vma->vm_file ||
1428             atomic_read(&vma->vm_region->vm_usage) != 1)
1429                 return -ENOMEM;
1430
1431         if (mm->map_count >= sysctl_max_map_count)
1432                 return -ENOMEM;
1433
1434         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1435         if (!region)
1436                 return -ENOMEM;
1437
1438         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1439         if (!new) {
1440                 kmem_cache_free(vm_region_jar, region);
1441                 return -ENOMEM;
1442         }
1443
1444         /* most fields are the same, copy all, and then fixup */
1445         *new = *vma;
1446         *region = *vma->vm_region;
1447         new->vm_region = region;
1448
1449         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1450
1451         if (new_below) {
1452                 region->vm_top = region->vm_end = new->vm_end = addr;
1453         } else {
1454                 region->vm_start = new->vm_start = addr;
1455                 region->vm_pgoff = new->vm_pgoff += npages;
1456         }
1457
1458         if (new->vm_ops && new->vm_ops->open)
1459                 new->vm_ops->open(new);
1460
1461         delete_vma_from_mm(vma);
1462         down_write(&nommu_region_sem);
1463         delete_nommu_region(vma->vm_region);
1464         if (new_below) {
1465                 vma->vm_region->vm_start = vma->vm_start = addr;
1466                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1467         } else {
1468                 vma->vm_region->vm_end = vma->vm_end = addr;
1469                 vma->vm_region->vm_top = addr;
1470         }
1471         add_nommu_region(vma->vm_region);
1472         add_nommu_region(new->vm_region);
1473         up_write(&nommu_region_sem);
1474         add_vma_to_mm(mm, vma);
1475         add_vma_to_mm(mm, new);
1476         return 0;
1477 }
1478
1479 /*
1480  * shrink a VMA by removing the specified chunk from either the beginning or
1481  * the end
1482  */
1483 static int shrink_vma(struct mm_struct *mm,
1484                       struct vm_area_struct *vma,
1485                       unsigned long from, unsigned long to)
1486 {
1487         struct vm_region *region;
1488
1489         kenter("");
1490
1491         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1492          * and list */
1493         delete_vma_from_mm(vma);
1494         if (from > vma->vm_start)
1495                 vma->vm_end = from;
1496         else
1497                 vma->vm_start = to;
1498         add_vma_to_mm(mm, vma);
1499
1500         /* cut the backing region down to size */
1501         region = vma->vm_region;
1502         BUG_ON(atomic_read(&region->vm_usage) != 1);
1503
1504         down_write(&nommu_region_sem);
1505         delete_nommu_region(region);
1506         if (from > region->vm_start) {
1507                 to = region->vm_top;
1508                 region->vm_top = region->vm_end = from;
1509         } else {
1510                 region->vm_start = to;
1511         }
1512         add_nommu_region(region);
1513         up_write(&nommu_region_sem);
1514
1515         free_page_series(from, to);
1516         return 0;
1517 }
1518
1519 /*
1520  * release a mapping
1521  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1522  *   VMA, though it need not cover the whole VMA
1523  */
1524 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1525 {
1526         struct vm_area_struct *vma;
1527         struct rb_node *rb;
1528         unsigned long end = start + len;
1529         int ret;
1530
1531         kenter(",%lx,%zx", start, len);
1532
1533         if (len == 0)
1534                 return -EINVAL;
1535
1536         /* find the first potentially overlapping VMA */
1537         vma = find_vma(mm, start);
1538         if (!vma) {
1539                 printk(KERN_WARNING
1540                        "munmap of memory not mmapped by process %d (%s):"
1541                        " 0x%lx-0x%lx\n",
1542                        current->pid, current->comm, start, start + len - 1);
1543                 return -EINVAL;
1544         }
1545
1546         /* we're allowed to split an anonymous VMA but not a file-backed one */
1547         if (vma->vm_file) {
1548                 do {
1549                         if (start > vma->vm_start) {
1550                                 kleave(" = -EINVAL [miss]");
1551                                 return -EINVAL;
1552                         }
1553                         if (end == vma->vm_end)
1554                                 goto erase_whole_vma;
1555                         rb = rb_next(&vma->vm_rb);
1556                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1557                 } while (rb);
1558                 kleave(" = -EINVAL [split file]");
1559                 return -EINVAL;
1560         } else {
1561                 /* the chunk must be a subset of the VMA found */
1562                 if (start == vma->vm_start && end == vma->vm_end)
1563                         goto erase_whole_vma;
1564                 if (start < vma->vm_start || end > vma->vm_end) {
1565                         kleave(" = -EINVAL [superset]");
1566                         return -EINVAL;
1567                 }
1568                 if (start & ~PAGE_MASK) {
1569                         kleave(" = -EINVAL [unaligned start]");
1570                         return -EINVAL;
1571                 }
1572                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1573                         kleave(" = -EINVAL [unaligned split]");
1574                         return -EINVAL;
1575                 }
1576                 if (start != vma->vm_start && end != vma->vm_end) {
1577                         ret = split_vma(mm, vma, start, 1);
1578                         if (ret < 0) {
1579                                 kleave(" = %d [split]", ret);
1580                                 return ret;
1581                         }
1582                 }
1583                 return shrink_vma(mm, vma, start, end);
1584         }
1585
1586 erase_whole_vma:
1587         delete_vma_from_mm(vma);
1588         delete_vma(mm, vma);
1589         kleave(" = 0");
1590         return 0;
1591 }
1592 EXPORT_SYMBOL(do_munmap);
1593
1594 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1595 {
1596         int ret;
1597         struct mm_struct *mm = current->mm;
1598
1599         down_write(&mm->mmap_sem);
1600         ret = do_munmap(mm, addr, len);
1601         up_write(&mm->mmap_sem);
1602         return ret;
1603 }
1604
1605 /*
1606  * release all the mappings made in a process's VM space
1607  */
1608 void exit_mmap(struct mm_struct *mm)
1609 {
1610         struct vm_area_struct *vma;
1611
1612         if (!mm)
1613                 return;
1614
1615         kenter("");
1616
1617         mm->total_vm = 0;
1618
1619         while ((vma = mm->mmap)) {
1620                 mm->mmap = vma->vm_next;
1621                 delete_vma_from_mm(vma);
1622                 delete_vma(mm, vma);
1623         }
1624
1625         kleave("");
1626 }
1627
1628 unsigned long do_brk(unsigned long addr, unsigned long len)
1629 {
1630         return -ENOMEM;
1631 }
1632
1633 /*
1634  * expand (or shrink) an existing mapping, potentially moving it at the same
1635  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1636  *
1637  * under NOMMU conditions, we only permit changing a mapping's size, and only
1638  * as long as it stays within the region allocated by do_mmap_private() and the
1639  * block is not shareable
1640  *
1641  * MREMAP_FIXED is not supported under NOMMU conditions
1642  */
1643 unsigned long do_mremap(unsigned long addr,
1644                         unsigned long old_len, unsigned long new_len,
1645                         unsigned long flags, unsigned long new_addr)
1646 {
1647         struct vm_area_struct *vma;
1648
1649         /* insanity checks first */
1650         if (old_len == 0 || new_len == 0)
1651                 return (unsigned long) -EINVAL;
1652
1653         if (addr & ~PAGE_MASK)
1654                 return -EINVAL;
1655
1656         if (flags & MREMAP_FIXED && new_addr != addr)
1657                 return (unsigned long) -EINVAL;
1658
1659         vma = find_vma_exact(current->mm, addr, old_len);
1660         if (!vma)
1661                 return (unsigned long) -EINVAL;
1662
1663         if (vma->vm_end != vma->vm_start + old_len)
1664                 return (unsigned long) -EFAULT;
1665
1666         if (vma->vm_flags & VM_MAYSHARE)
1667                 return (unsigned long) -EPERM;
1668
1669         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1670                 return (unsigned long) -ENOMEM;
1671
1672         /* all checks complete - do it */
1673         vma->vm_end = vma->vm_start + new_len;
1674         return vma->vm_start;
1675 }
1676 EXPORT_SYMBOL(do_mremap);
1677
1678 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1679                 unsigned long, new_len, unsigned long, flags,
1680                 unsigned long, new_addr)
1681 {
1682         unsigned long ret;
1683
1684         down_write(&current->mm->mmap_sem);
1685         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1686         up_write(&current->mm->mmap_sem);
1687         return ret;
1688 }
1689
1690 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1691                         unsigned int foll_flags)
1692 {
1693         return NULL;
1694 }
1695
1696 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1697                 unsigned long to, unsigned long size, pgprot_t prot)
1698 {
1699         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1700         return 0;
1701 }
1702 EXPORT_SYMBOL(remap_pfn_range);
1703
1704 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1705                         unsigned long pgoff)
1706 {
1707         unsigned int size = vma->vm_end - vma->vm_start;
1708
1709         if (!(vma->vm_flags & VM_USERMAP))
1710                 return -EINVAL;
1711
1712         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1713         vma->vm_end = vma->vm_start + size;
1714
1715         return 0;
1716 }
1717 EXPORT_SYMBOL(remap_vmalloc_range);
1718
1719 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1720 {
1721 }
1722
1723 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1724         unsigned long len, unsigned long pgoff, unsigned long flags)
1725 {
1726         return -ENOMEM;
1727 }
1728
1729 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1730 {
1731 }
1732
1733 void unmap_mapping_range(struct address_space *mapping,
1734                          loff_t const holebegin, loff_t const holelen,
1735                          int even_cows)
1736 {
1737 }
1738 EXPORT_SYMBOL(unmap_mapping_range);
1739
1740 /*
1741  * ask for an unmapped area at which to create a mapping on a file
1742  */
1743 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1744                                 unsigned long len, unsigned long pgoff,
1745                                 unsigned long flags)
1746 {
1747         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1748                                   unsigned long, unsigned long);
1749
1750         get_area = current->mm->get_unmapped_area;
1751         if (file && file->f_op && file->f_op->get_unmapped_area)
1752                 get_area = file->f_op->get_unmapped_area;
1753
1754         if (!get_area)
1755                 return -ENOSYS;
1756
1757         return get_area(file, addr, len, pgoff, flags);
1758 }
1759 EXPORT_SYMBOL(get_unmapped_area);
1760
1761 /*
1762  * Check that a process has enough memory to allocate a new virtual
1763  * mapping. 0 means there is enough memory for the allocation to
1764  * succeed and -ENOMEM implies there is not.
1765  *
1766  * We currently support three overcommit policies, which are set via the
1767  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1768  *
1769  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1770  * Additional code 2002 Jul 20 by Robert Love.
1771  *
1772  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1773  *
1774  * Note this is a helper function intended to be used by LSMs which
1775  * wish to use this logic.
1776  */
1777 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1778 {
1779         unsigned long free, allowed;
1780
1781         vm_acct_memory(pages);
1782
1783         /*
1784          * Sometimes we want to use more memory than we have
1785          */
1786         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1787                 return 0;
1788
1789         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1790                 unsigned long n;
1791
1792                 free = global_page_state(NR_FILE_PAGES);
1793                 free += nr_swap_pages;
1794
1795                 /*
1796                  * Any slabs which are created with the
1797                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1798                  * which are reclaimable, under pressure.  The dentry
1799                  * cache and most inode caches should fall into this
1800                  */
1801                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1802
1803                 /*
1804                  * Leave the last 3% for root
1805                  */
1806                 if (!cap_sys_admin)
1807                         free -= free / 32;
1808
1809                 if (free > pages)
1810                         return 0;
1811
1812                 /*
1813                  * nr_free_pages() is very expensive on large systems,
1814                  * only call if we're about to fail.
1815                  */
1816                 n = nr_free_pages();
1817
1818                 /*
1819                  * Leave reserved pages. The pages are not for anonymous pages.
1820                  */
1821                 if (n <= totalreserve_pages)
1822                         goto error;
1823                 else
1824                         n -= totalreserve_pages;
1825
1826                 /*
1827                  * Leave the last 3% for root
1828                  */
1829                 if (!cap_sys_admin)
1830                         n -= n / 32;
1831                 free += n;
1832
1833                 if (free > pages)
1834                         return 0;
1835
1836                 goto error;
1837         }
1838
1839         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1840         /*
1841          * Leave the last 3% for root
1842          */
1843         if (!cap_sys_admin)
1844                 allowed -= allowed / 32;
1845         allowed += total_swap_pages;
1846
1847         /* Don't let a single process grow too big:
1848            leave 3% of the size of this process for other processes */
1849         if (mm)
1850                 allowed -= mm->total_vm / 32;
1851
1852         /*
1853          * cast `allowed' as a signed long because vm_committed_space
1854          * sometimes has a negative value
1855          */
1856         if (atomic_long_read(&vm_committed_space) < (long)allowed)
1857                 return 0;
1858 error:
1859         vm_unacct_memory(pages);
1860
1861         return -ENOMEM;
1862 }
1863
1864 int in_gate_area_no_task(unsigned long addr)
1865 {
1866         return 0;
1867 }
1868
1869 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1870 {
1871         BUG();
1872         return 0;
1873 }
1874 EXPORT_SYMBOL(filemap_fault);
1875
1876 /*
1877  * Access another process' address space.
1878  * - source/target buffer must be kernel space
1879  */
1880 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1881 {
1882         struct vm_area_struct *vma;
1883         struct mm_struct *mm;
1884
1885         if (addr + len < addr)
1886                 return 0;
1887
1888         mm = get_task_mm(tsk);
1889         if (!mm)
1890                 return 0;
1891
1892         down_read(&mm->mmap_sem);
1893
1894         /* the access must start within one of the target process's mappings */
1895         vma = find_vma(mm, addr);
1896         if (vma) {
1897                 /* don't overrun this mapping */
1898                 if (addr + len >= vma->vm_end)
1899                         len = vma->vm_end - addr;
1900
1901                 /* only read or write mappings where it is permitted */
1902                 if (write && vma->vm_flags & VM_MAYWRITE)
1903                         len -= copy_to_user((void *) addr, buf, len);
1904                 else if (!write && vma->vm_flags & VM_MAYREAD)
1905                         len -= copy_from_user(buf, (void *) addr, len);
1906                 else
1907                         len = 0;
1908         } else {
1909                 len = 0;
1910         }
1911
1912         up_read(&mm->mmap_sem);
1913         mmput(mm);
1914         return len;
1915 }