media: video: tegra: sh532u: fix out-of-bounds read
[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) 2007-2010 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/blkdev.h>
26 #include <linux/backing-dev.h>
27 #include <linux/mount.h>
28 #include <linux/personality.h>
29 #include <linux/security.h>
30 #include <linux/syscalls.h>
31 #include <linux/audit.h>
32
33 #include <asm/uaccess.h>
34 #include <asm/tlb.h>
35 #include <asm/tlbflush.h>
36 #include <asm/mmu_context.h>
37 #include "internal.h"
38
39 #if 0
40 #define kenter(FMT, ...) \
41         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
42 #define kleave(FMT, ...) \
43         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
44 #define kdebug(FMT, ...) \
45         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
46 #else
47 #define kenter(FMT, ...) \
48         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
49 #define kleave(FMT, ...) \
50         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
51 #define kdebug(FMT, ...) \
52         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
53 #endif
54
55 void *high_memory;
56 struct page *mem_map;
57 unsigned long max_mapnr;
58 unsigned long num_physpages;
59 unsigned long highest_memmap_pfn;
60 struct percpu_counter vm_committed_as;
61 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
62 int sysctl_overcommit_ratio = 50; /* default is 50% */
63 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
64 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
65 int heap_stack_gap = 0;
66
67 atomic_long_t mmap_pages_allocated;
68
69 EXPORT_SYMBOL(mem_map);
70 EXPORT_SYMBOL(num_physpages);
71
72 /* list of mapped, potentially shareable regions */
73 static struct kmem_cache *vm_region_jar;
74 struct rb_root nommu_region_tree = RB_ROOT;
75 DECLARE_RWSEM(nommu_region_sem);
76
77 const struct vm_operations_struct generic_file_vm_ops = {
78 };
79
80 /*
81  * Return the total memory allocated for this pointer, not
82  * just what the caller asked for.
83  *
84  * Doesn't have to be accurate, i.e. may have races.
85  */
86 unsigned int kobjsize(const void *objp)
87 {
88         struct page *page;
89
90         /*
91          * If the object we have should not have ksize performed on it,
92          * return size of 0
93          */
94         if (!objp || !virt_addr_valid(objp))
95                 return 0;
96
97         page = virt_to_head_page(objp);
98
99         /*
100          * If the allocator sets PageSlab, we know the pointer came from
101          * kmalloc().
102          */
103         if (PageSlab(page))
104                 return ksize(objp);
105
106         /*
107          * If it's not a compound page, see if we have a matching VMA
108          * region. This test is intentionally done in reverse order,
109          * so if there's no VMA, we still fall through and hand back
110          * PAGE_SIZE for 0-order pages.
111          */
112         if (!PageCompound(page)) {
113                 struct vm_area_struct *vma;
114
115                 vma = find_vma(current->mm, (unsigned long)objp);
116                 if (vma)
117                         return vma->vm_end - vma->vm_start;
118         }
119
120         /*
121          * The ksize() function is only guaranteed to work for pointers
122          * returned by kmalloc(). So handle arbitrary pointers here.
123          */
124         return PAGE_SIZE << compound_order(page);
125 }
126
127 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
128                      unsigned long start, int nr_pages, unsigned int foll_flags,
129                      struct page **pages, struct vm_area_struct **vmas,
130                      int *retry)
131 {
132         struct vm_area_struct *vma;
133         unsigned long vm_flags;
134         int i;
135
136         /* calculate required read or write permissions.
137          * If FOLL_FORCE is set, we only require the "MAY" flags.
138          */
139         vm_flags  = (foll_flags & FOLL_WRITE) ?
140                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
141         vm_flags &= (foll_flags & FOLL_FORCE) ?
142                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
143
144         for (i = 0; i < nr_pages; i++) {
145                 vma = find_vma(mm, start);
146                 if (!vma)
147                         goto finish_or_fault;
148
149                 /* protect what we can, including chardevs */
150                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
151                     !(vm_flags & vma->vm_flags))
152                         goto finish_or_fault;
153
154                 if (pages) {
155                         pages[i] = virt_to_page(start);
156                         if (pages[i])
157                                 page_cache_get(pages[i]);
158                 }
159                 if (vmas)
160                         vmas[i] = vma;
161                 start = (start + PAGE_SIZE) & PAGE_MASK;
162         }
163
164         return i;
165
166 finish_or_fault:
167         return i ? : -EFAULT;
168 }
169
170 /*
171  * get a list of pages in an address range belonging to the specified process
172  * and indicate the VMA that covers each page
173  * - this is potentially dodgy as we may end incrementing the page count of a
174  *   slab page or a secondary page from a compound page
175  * - don't permit access to VMAs that don't support it, such as I/O mappings
176  */
177 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
178         unsigned long start, int nr_pages, int write, int force,
179         struct page **pages, struct vm_area_struct **vmas)
180 {
181         int flags = 0;
182
183         if (write)
184                 flags |= FOLL_WRITE;
185         if (force)
186                 flags |= FOLL_FORCE;
187
188         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
189                                 NULL);
190 }
191 EXPORT_SYMBOL(get_user_pages);
192
193 /**
194  * follow_pfn - look up PFN at a user virtual address
195  * @vma: memory mapping
196  * @address: user virtual address
197  * @pfn: location to store found PFN
198  *
199  * Only IO mappings and raw PFN mappings are allowed.
200  *
201  * Returns zero and the pfn at @pfn on success, -ve otherwise.
202  */
203 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
204         unsigned long *pfn)
205 {
206         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
207                 return -EINVAL;
208
209         *pfn = address >> PAGE_SHIFT;
210         return 0;
211 }
212 EXPORT_SYMBOL(follow_pfn);
213
214 DEFINE_RWLOCK(vmlist_lock);
215 struct vm_struct *vmlist;
216
217 void vfree(const void *addr)
218 {
219         kfree(addr);
220 }
221 EXPORT_SYMBOL(vfree);
222
223 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
224 {
225         /*
226          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
227          * returns only a logical address.
228          */
229         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
230 }
231 EXPORT_SYMBOL(__vmalloc);
232
233 void *vmalloc_user(unsigned long size)
234 {
235         void *ret;
236
237         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
238                         PAGE_KERNEL);
239         if (ret) {
240                 struct vm_area_struct *vma;
241
242                 down_write(&current->mm->mmap_sem);
243                 vma = find_vma(current->mm, (unsigned long)ret);
244                 if (vma)
245                         vma->vm_flags |= VM_USERMAP;
246                 up_write(&current->mm->mmap_sem);
247         }
248
249         return ret;
250 }
251 EXPORT_SYMBOL(vmalloc_user);
252
253 struct page *vmalloc_to_page(const void *addr)
254 {
255         return virt_to_page(addr);
256 }
257 EXPORT_SYMBOL(vmalloc_to_page);
258
259 unsigned long vmalloc_to_pfn(const void *addr)
260 {
261         return page_to_pfn(virt_to_page(addr));
262 }
263 EXPORT_SYMBOL(vmalloc_to_pfn);
264
265 long vread(char *buf, char *addr, unsigned long count)
266 {
267         memcpy(buf, addr, count);
268         return count;
269 }
270
271 long vwrite(char *buf, char *addr, unsigned long count)
272 {
273         /* Don't allow overflow */
274         if ((unsigned long) addr + count < count)
275                 count = -(unsigned long) addr;
276
277         memcpy(addr, buf, count);
278         return(count);
279 }
280
281 /*
282  *      vmalloc  -  allocate virtually continguos memory
283  *
284  *      @size:          allocation size
285  *
286  *      Allocate enough pages to cover @size from the page level
287  *      allocator and map them into continguos kernel virtual space.
288  *
289  *      For tight control over page level allocator and protection flags
290  *      use __vmalloc() instead.
291  */
292 void *vmalloc(unsigned long size)
293 {
294        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
295 }
296 EXPORT_SYMBOL(vmalloc);
297
298 /*
299  *      vzalloc - allocate virtually continguos memory with zero fill
300  *
301  *      @size:          allocation size
302  *
303  *      Allocate enough pages to cover @size from the page level
304  *      allocator and map them into continguos kernel virtual space.
305  *      The memory allocated is set to zero.
306  *
307  *      For tight control over page level allocator and protection flags
308  *      use __vmalloc() instead.
309  */
310 void *vzalloc(unsigned long size)
311 {
312         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
313                         PAGE_KERNEL);
314 }
315 EXPORT_SYMBOL(vzalloc);
316
317 /**
318  * vmalloc_node - allocate memory on a specific node
319  * @size:       allocation size
320  * @node:       numa node
321  *
322  * Allocate enough pages to cover @size from the page level
323  * allocator and map them into contiguous kernel virtual space.
324  *
325  * For tight control over page level allocator and protection flags
326  * use __vmalloc() instead.
327  */
328 void *vmalloc_node(unsigned long size, int node)
329 {
330         return vmalloc(size);
331 }
332 EXPORT_SYMBOL(vmalloc_node);
333
334 /**
335  * vzalloc_node - allocate memory on a specific node with zero fill
336  * @size:       allocation size
337  * @node:       numa node
338  *
339  * Allocate enough pages to cover @size from the page level
340  * allocator and map them into contiguous kernel virtual space.
341  * The memory allocated is set to zero.
342  *
343  * For tight control over page level allocator and protection flags
344  * use __vmalloc() instead.
345  */
346 void *vzalloc_node(unsigned long size, int node)
347 {
348         return vzalloc(size);
349 }
350 EXPORT_SYMBOL(vzalloc_node);
351
352 #ifndef PAGE_KERNEL_EXEC
353 # define PAGE_KERNEL_EXEC PAGE_KERNEL
354 #endif
355
356 /**
357  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
358  *      @size:          allocation size
359  *
360  *      Kernel-internal function to allocate enough pages to cover @size
361  *      the page level allocator and map them into contiguous and
362  *      executable kernel virtual space.
363  *
364  *      For tight control over page level allocator and protection flags
365  *      use __vmalloc() instead.
366  */
367
368 void *vmalloc_exec(unsigned long size)
369 {
370         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
371 }
372
373 /**
374  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
375  *      @size:          allocation size
376  *
377  *      Allocate enough 32bit PA addressable pages to cover @size from the
378  *      page level allocator and map them into continguos kernel virtual space.
379  */
380 void *vmalloc_32(unsigned long size)
381 {
382         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
383 }
384 EXPORT_SYMBOL(vmalloc_32);
385
386 /**
387  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
388  *      @size:          allocation size
389  *
390  * The resulting memory area is 32bit addressable and zeroed so it can be
391  * mapped to userspace without leaking data.
392  *
393  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
394  * remap_vmalloc_range() are permissible.
395  */
396 void *vmalloc_32_user(unsigned long size)
397 {
398         /*
399          * We'll have to sort out the ZONE_DMA bits for 64-bit,
400          * but for now this can simply use vmalloc_user() directly.
401          */
402         return vmalloc_user(size);
403 }
404 EXPORT_SYMBOL(vmalloc_32_user);
405
406 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
407 {
408         BUG();
409         return NULL;
410 }
411 EXPORT_SYMBOL(vmap);
412
413 void vunmap(const void *addr)
414 {
415         BUG();
416 }
417 EXPORT_SYMBOL(vunmap);
418
419 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
420 {
421         BUG();
422         return NULL;
423 }
424 EXPORT_SYMBOL(vm_map_ram);
425
426 void vm_unmap_ram(const void *mem, unsigned int count)
427 {
428         BUG();
429 }
430 EXPORT_SYMBOL(vm_unmap_ram);
431
432 void vm_unmap_aliases(void)
433 {
434 }
435 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
436
437 /*
438  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
439  * have one.
440  */
441 void  __attribute__((weak)) vmalloc_sync_all(void)
442 {
443 }
444
445 /**
446  *      alloc_vm_area - allocate a range of kernel address space
447  *      @size:          size of the area
448  *
449  *      Returns:        NULL on failure, vm_struct on success
450  *
451  *      This function reserves a range of kernel address space, and
452  *      allocates pagetables to map that range.  No actual mappings
453  *      are created.  If the kernel address space is not shared
454  *      between processes, it syncs the pagetable across all
455  *      processes.
456  */
457 struct vm_struct *alloc_vm_area(size_t size)
458 {
459         BUG();
460         return NULL;
461 }
462 EXPORT_SYMBOL_GPL(alloc_vm_area);
463
464 void free_vm_area(struct vm_struct *area)
465 {
466         BUG();
467 }
468 EXPORT_SYMBOL_GPL(free_vm_area);
469
470 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
471                    struct page *page)
472 {
473         return -EINVAL;
474 }
475 EXPORT_SYMBOL(vm_insert_page);
476
477 /*
478  *  sys_brk() for the most part doesn't need the global kernel
479  *  lock, except when an application is doing something nasty
480  *  like trying to un-brk an area that has already been mapped
481  *  to a regular file.  in this case, the unmapping will need
482  *  to invoke file system routines that need the global lock.
483  */
484 SYSCALL_DEFINE1(brk, unsigned long, brk)
485 {
486         struct mm_struct *mm = current->mm;
487
488         if (brk < mm->start_brk || brk > mm->context.end_brk)
489                 return mm->brk;
490
491         if (mm->brk == brk)
492                 return mm->brk;
493
494         /*
495          * Always allow shrinking brk
496          */
497         if (brk <= mm->brk) {
498                 mm->brk = brk;
499                 return brk;
500         }
501
502         /*
503          * Ok, looks good - let it rip.
504          */
505         flush_icache_range(mm->brk, brk);
506         return mm->brk = brk;
507 }
508
509 /*
510  * initialise the VMA and region record slabs
511  */
512 void __init mmap_init(void)
513 {
514         int ret;
515
516         ret = percpu_counter_init(&vm_committed_as, 0);
517         VM_BUG_ON(ret);
518         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
519 }
520
521 /*
522  * validate the region tree
523  * - the caller must hold the region lock
524  */
525 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
526 static noinline void validate_nommu_regions(void)
527 {
528         struct vm_region *region, *last;
529         struct rb_node *p, *lastp;
530
531         lastp = rb_first(&nommu_region_tree);
532         if (!lastp)
533                 return;
534
535         last = rb_entry(lastp, struct vm_region, vm_rb);
536         BUG_ON(unlikely(last->vm_end <= last->vm_start));
537         BUG_ON(unlikely(last->vm_top < last->vm_end));
538
539         while ((p = rb_next(lastp))) {
540                 region = rb_entry(p, struct vm_region, vm_rb);
541                 last = rb_entry(lastp, struct vm_region, vm_rb);
542
543                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
544                 BUG_ON(unlikely(region->vm_top < region->vm_end));
545                 BUG_ON(unlikely(region->vm_start < last->vm_top));
546
547                 lastp = p;
548         }
549 }
550 #else
551 static void validate_nommu_regions(void)
552 {
553 }
554 #endif
555
556 /*
557  * add a region into the global tree
558  */
559 static void add_nommu_region(struct vm_region *region)
560 {
561         struct vm_region *pregion;
562         struct rb_node **p, *parent;
563
564         validate_nommu_regions();
565
566         parent = NULL;
567         p = &nommu_region_tree.rb_node;
568         while (*p) {
569                 parent = *p;
570                 pregion = rb_entry(parent, struct vm_region, vm_rb);
571                 if (region->vm_start < pregion->vm_start)
572                         p = &(*p)->rb_left;
573                 else if (region->vm_start > pregion->vm_start)
574                         p = &(*p)->rb_right;
575                 else if (pregion == region)
576                         return;
577                 else
578                         BUG();
579         }
580
581         rb_link_node(&region->vm_rb, parent, p);
582         rb_insert_color(&region->vm_rb, &nommu_region_tree);
583
584         validate_nommu_regions();
585 }
586
587 /*
588  * delete a region from the global tree
589  */
590 static void delete_nommu_region(struct vm_region *region)
591 {
592         BUG_ON(!nommu_region_tree.rb_node);
593
594         validate_nommu_regions();
595         rb_erase(&region->vm_rb, &nommu_region_tree);
596         validate_nommu_regions();
597 }
598
599 /*
600  * free a contiguous series of pages
601  */
602 static void free_page_series(unsigned long from, unsigned long to)
603 {
604         for (; from < to; from += PAGE_SIZE) {
605                 struct page *page = virt_to_page(from);
606
607                 kdebug("- free %lx", from);
608                 atomic_long_dec(&mmap_pages_allocated);
609                 if (page_count(page) != 1)
610                         kdebug("free page %p: refcount not one: %d",
611                                page, page_count(page));
612                 put_page(page);
613         }
614 }
615
616 /*
617  * release a reference to a region
618  * - the caller must hold the region semaphore for writing, which this releases
619  * - the region may not have been added to the tree yet, in which case vm_top
620  *   will equal vm_start
621  */
622 static void __put_nommu_region(struct vm_region *region)
623         __releases(nommu_region_sem)
624 {
625         kenter("%p{%d}", region, region->vm_usage);
626
627         BUG_ON(!nommu_region_tree.rb_node);
628
629         if (--region->vm_usage == 0) {
630                 if (region->vm_top > region->vm_start)
631                         delete_nommu_region(region);
632                 up_write(&nommu_region_sem);
633
634                 if (region->vm_file)
635                         fput(region->vm_file);
636
637                 /* IO memory and memory shared directly out of the pagecache
638                  * from ramfs/tmpfs mustn't be released here */
639                 if (region->vm_flags & VM_MAPPED_COPY) {
640                         kdebug("free series");
641                         free_page_series(region->vm_start, region->vm_top);
642                 }
643                 kmem_cache_free(vm_region_jar, region);
644         } else {
645                 up_write(&nommu_region_sem);
646         }
647 }
648
649 /*
650  * release a reference to a region
651  */
652 static void put_nommu_region(struct vm_region *region)
653 {
654         down_write(&nommu_region_sem);
655         __put_nommu_region(region);
656 }
657
658 /*
659  * update protection on a vma
660  */
661 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
662 {
663 #ifdef CONFIG_MPU
664         struct mm_struct *mm = vma->vm_mm;
665         long start = vma->vm_start & PAGE_MASK;
666         while (start < vma->vm_end) {
667                 protect_page(mm, start, flags);
668                 start += PAGE_SIZE;
669         }
670         update_protections(mm);
671 #endif
672 }
673
674 /*
675  * add a VMA into a process's mm_struct in the appropriate place in the list
676  * and tree and add to the address space's page tree also if not an anonymous
677  * page
678  * - should be called with mm->mmap_sem held writelocked
679  */
680 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
681 {
682         struct vm_area_struct *pvma, *prev;
683         struct address_space *mapping;
684         struct rb_node **p, *parent, *rb_prev;
685
686         kenter(",%p", vma);
687
688         BUG_ON(!vma->vm_region);
689
690         mm->map_count++;
691         vma->vm_mm = mm;
692
693         protect_vma(vma, vma->vm_flags);
694
695         /* add the VMA to the mapping */
696         if (vma->vm_file) {
697                 mapping = vma->vm_file->f_mapping;
698
699                 flush_dcache_mmap_lock(mapping);
700                 vma_prio_tree_insert(vma, &mapping->i_mmap);
701                 flush_dcache_mmap_unlock(mapping);
702         }
703
704         /* add the VMA to the tree */
705         parent = rb_prev = NULL;
706         p = &mm->mm_rb.rb_node;
707         while (*p) {
708                 parent = *p;
709                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
710
711                 /* sort by: start addr, end addr, VMA struct addr in that order
712                  * (the latter is necessary as we may get identical VMAs) */
713                 if (vma->vm_start < pvma->vm_start)
714                         p = &(*p)->rb_left;
715                 else if (vma->vm_start > pvma->vm_start) {
716                         rb_prev = parent;
717                         p = &(*p)->rb_right;
718                 } else if (vma->vm_end < pvma->vm_end)
719                         p = &(*p)->rb_left;
720                 else if (vma->vm_end > pvma->vm_end) {
721                         rb_prev = parent;
722                         p = &(*p)->rb_right;
723                 } else if (vma < pvma)
724                         p = &(*p)->rb_left;
725                 else if (vma > pvma) {
726                         rb_prev = parent;
727                         p = &(*p)->rb_right;
728                 } else
729                         BUG();
730         }
731
732         rb_link_node(&vma->vm_rb, parent, p);
733         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
734
735         /* add VMA to the VMA list also */
736         prev = NULL;
737         if (rb_prev)
738                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
739
740         __vma_link_list(mm, vma, prev, parent);
741 }
742
743 /*
744  * delete a VMA from its owning mm_struct and address space
745  */
746 static void delete_vma_from_mm(struct vm_area_struct *vma)
747 {
748         struct address_space *mapping;
749         struct mm_struct *mm = vma->vm_mm;
750
751         kenter("%p", vma);
752
753         protect_vma(vma, 0);
754
755         mm->map_count--;
756         if (mm->mmap_cache == vma)
757                 mm->mmap_cache = NULL;
758
759         /* remove the VMA from the mapping */
760         if (vma->vm_file) {
761                 mapping = vma->vm_file->f_mapping;
762
763                 flush_dcache_mmap_lock(mapping);
764                 vma_prio_tree_remove(vma, &mapping->i_mmap);
765                 flush_dcache_mmap_unlock(mapping);
766         }
767
768         /* remove from the MM's tree and list */
769         rb_erase(&vma->vm_rb, &mm->mm_rb);
770
771         if (vma->vm_prev)
772                 vma->vm_prev->vm_next = vma->vm_next;
773         else
774                 mm->mmap = vma->vm_next;
775
776         if (vma->vm_next)
777                 vma->vm_next->vm_prev = vma->vm_prev;
778
779         vma->vm_mm = NULL;
780 }
781
782 /*
783  * destroy a VMA record
784  */
785 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
786 {
787         kenter("%p", vma);
788         if (vma->vm_ops && vma->vm_ops->close)
789                 vma->vm_ops->close(vma);
790         if (vma->vm_file) {
791                 fput(vma->vm_file);
792                 if (vma->vm_flags & VM_EXECUTABLE)
793                         removed_exe_file_vma(mm);
794         }
795         put_nommu_region(vma->vm_region);
796         kmem_cache_free(vm_area_cachep, vma);
797 }
798
799 /*
800  * look up the first VMA in which addr resides, NULL if none
801  * - should be called with mm->mmap_sem at least held readlocked
802  */
803 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
804 {
805         struct vm_area_struct *vma;
806
807         /* check the cache first */
808         vma = mm->mmap_cache;
809         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
810                 return vma;
811
812         /* trawl the list (there may be multiple mappings in which addr
813          * resides) */
814         for (vma = mm->mmap; vma; vma = vma->vm_next) {
815                 if (vma->vm_start > addr)
816                         return NULL;
817                 if (vma->vm_end > addr) {
818                         mm->mmap_cache = vma;
819                         return vma;
820                 }
821         }
822
823         return NULL;
824 }
825 EXPORT_SYMBOL(find_vma);
826
827 /*
828  * find a VMA
829  * - we don't extend stack VMAs under NOMMU conditions
830  */
831 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
832 {
833         return find_vma(mm, addr);
834 }
835
836 /*
837  * expand a stack to a given address
838  * - not supported under NOMMU conditions
839  */
840 int expand_stack(struct vm_area_struct *vma, unsigned long address)
841 {
842         return -ENOMEM;
843 }
844
845 /*
846  * look up the first VMA exactly that exactly matches addr
847  * - should be called with mm->mmap_sem at least held readlocked
848  */
849 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
850                                              unsigned long addr,
851                                              unsigned long len)
852 {
853         struct vm_area_struct *vma;
854         unsigned long end = addr + len;
855
856         /* check the cache first */
857         vma = mm->mmap_cache;
858         if (vma && vma->vm_start == addr && vma->vm_end == end)
859                 return vma;
860
861         /* trawl the list (there may be multiple mappings in which addr
862          * resides) */
863         for (vma = mm->mmap; vma; vma = vma->vm_next) {
864                 if (vma->vm_start < addr)
865                         continue;
866                 if (vma->vm_start > addr)
867                         return NULL;
868                 if (vma->vm_end == end) {
869                         mm->mmap_cache = vma;
870                         return vma;
871                 }
872         }
873
874         return NULL;
875 }
876
877 /*
878  * determine whether a mapping should be permitted and, if so, what sort of
879  * mapping we're capable of supporting
880  */
881 static int validate_mmap_request(struct file *file,
882                                  unsigned long addr,
883                                  unsigned long len,
884                                  unsigned long prot,
885                                  unsigned long flags,
886                                  unsigned long pgoff,
887                                  unsigned long *_capabilities)
888 {
889         unsigned long capabilities, rlen;
890         unsigned long reqprot = prot;
891         int ret;
892
893         /* do the simple checks first */
894         if (flags & MAP_FIXED) {
895                 printk(KERN_DEBUG
896                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
897                        current->pid);
898                 return -EINVAL;
899         }
900
901         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
902             (flags & MAP_TYPE) != MAP_SHARED)
903                 return -EINVAL;
904
905         if (!len)
906                 return -EINVAL;
907
908         /* Careful about overflows.. */
909         rlen = PAGE_ALIGN(len);
910         if (!rlen || rlen > TASK_SIZE)
911                 return -ENOMEM;
912
913         /* offset overflow? */
914         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
915                 return -EOVERFLOW;
916
917         if (file) {
918                 /* validate file mapping requests */
919                 struct address_space *mapping;
920
921                 /* files must support mmap */
922                 if (!file->f_op || !file->f_op->mmap)
923                         return -ENODEV;
924
925                 /* work out if what we've got could possibly be shared
926                  * - we support chardevs that provide their own "memory"
927                  * - we support files/blockdevs that are memory backed
928                  */
929                 mapping = file->f_mapping;
930                 if (!mapping)
931                         mapping = file->f_path.dentry->d_inode->i_mapping;
932
933                 capabilities = 0;
934                 if (mapping && mapping->backing_dev_info)
935                         capabilities = mapping->backing_dev_info->capabilities;
936
937                 if (!capabilities) {
938                         /* no explicit capabilities set, so assume some
939                          * defaults */
940                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
941                         case S_IFREG:
942                         case S_IFBLK:
943                                 capabilities = BDI_CAP_MAP_COPY;
944                                 break;
945
946                         case S_IFCHR:
947                                 capabilities =
948                                         BDI_CAP_MAP_DIRECT |
949                                         BDI_CAP_READ_MAP |
950                                         BDI_CAP_WRITE_MAP;
951                                 break;
952
953                         default:
954                                 return -EINVAL;
955                         }
956                 }
957
958                 /* eliminate any capabilities that we can't support on this
959                  * device */
960                 if (!file->f_op->get_unmapped_area)
961                         capabilities &= ~BDI_CAP_MAP_DIRECT;
962                 if (!file->f_op->read)
963                         capabilities &= ~BDI_CAP_MAP_COPY;
964
965                 /* The file shall have been opened with read permission. */
966                 if (!(file->f_mode & FMODE_READ))
967                         return -EACCES;
968
969                 if (flags & MAP_SHARED) {
970                         /* do checks for writing, appending and locking */
971                         if ((prot & PROT_WRITE) &&
972                             !(file->f_mode & FMODE_WRITE))
973                                 return -EACCES;
974
975                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
976                             (file->f_mode & FMODE_WRITE))
977                                 return -EACCES;
978
979                         if (locks_verify_locked(file->f_path.dentry->d_inode))
980                                 return -EAGAIN;
981
982                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
983                                 return -ENODEV;
984
985                         /* we mustn't privatise shared mappings */
986                         capabilities &= ~BDI_CAP_MAP_COPY;
987                 }
988                 else {
989                         /* we're going to read the file into private memory we
990                          * allocate */
991                         if (!(capabilities & BDI_CAP_MAP_COPY))
992                                 return -ENODEV;
993
994                         /* we don't permit a private writable mapping to be
995                          * shared with the backing device */
996                         if (prot & PROT_WRITE)
997                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
998                 }
999
1000                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1001                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1002                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1003                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1004                             ) {
1005                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1006                                 if (flags & MAP_SHARED) {
1007                                         printk(KERN_WARNING
1008                                                "MAP_SHARED not completely supported on !MMU\n");
1009                                         return -EINVAL;
1010                                 }
1011                         }
1012                 }
1013
1014                 /* handle executable mappings and implied executable
1015                  * mappings */
1016                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1017                         if (prot & PROT_EXEC)
1018                                 return -EPERM;
1019                 }
1020                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1021                         /* handle implication of PROT_EXEC by PROT_READ */
1022                         if (current->personality & READ_IMPLIES_EXEC) {
1023                                 if (capabilities & BDI_CAP_EXEC_MAP)
1024                                         prot |= PROT_EXEC;
1025                         }
1026                 }
1027                 else if ((prot & PROT_READ) &&
1028                          (prot & PROT_EXEC) &&
1029                          !(capabilities & BDI_CAP_EXEC_MAP)
1030                          ) {
1031                         /* backing file is not executable, try to copy */
1032                         capabilities &= ~BDI_CAP_MAP_DIRECT;
1033                 }
1034         }
1035         else {
1036                 /* anonymous mappings are always memory backed and can be
1037                  * privately mapped
1038                  */
1039                 capabilities = BDI_CAP_MAP_COPY;
1040
1041                 /* handle PROT_EXEC implication by PROT_READ */
1042                 if ((prot & PROT_READ) &&
1043                     (current->personality & READ_IMPLIES_EXEC))
1044                         prot |= PROT_EXEC;
1045         }
1046
1047         /* allow the security API to have its say */
1048         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1049         if (ret < 0)
1050                 return ret;
1051
1052         /* looks okay */
1053         *_capabilities = capabilities;
1054         return 0;
1055 }
1056
1057 /*
1058  * we've determined that we can make the mapping, now translate what we
1059  * now know into VMA flags
1060  */
1061 static unsigned long determine_vm_flags(struct file *file,
1062                                         unsigned long prot,
1063                                         unsigned long flags,
1064                                         unsigned long capabilities)
1065 {
1066         unsigned long vm_flags;
1067
1068         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1069         /* vm_flags |= mm->def_flags; */
1070
1071         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1072                 /* attempt to share read-only copies of mapped file chunks */
1073                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1074                 if (file && !(prot & PROT_WRITE))
1075                         vm_flags |= VM_MAYSHARE;
1076         } else {
1077                 /* overlay a shareable mapping on the backing device or inode
1078                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1079                  * romfs/cramfs */
1080                 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1081                 if (flags & MAP_SHARED)
1082                         vm_flags |= VM_SHARED;
1083         }
1084
1085         /* refuse to let anyone share private mappings with this process if
1086          * it's being traced - otherwise breakpoints set in it may interfere
1087          * with another untraced process
1088          */
1089         if ((flags & MAP_PRIVATE) && current->ptrace)
1090                 vm_flags &= ~VM_MAYSHARE;
1091
1092         return vm_flags;
1093 }
1094
1095 /*
1096  * set up a shared mapping on a file (the driver or filesystem provides and
1097  * pins the storage)
1098  */
1099 static int do_mmap_shared_file(struct vm_area_struct *vma)
1100 {
1101         int ret;
1102
1103         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1104         if (ret == 0) {
1105                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1106                 return 0;
1107         }
1108         if (ret != -ENOSYS)
1109                 return ret;
1110
1111         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1112          * opposed to tried but failed) so we can only give a suitable error as
1113          * it's not possible to make a private copy if MAP_SHARED was given */
1114         return -ENODEV;
1115 }
1116
1117 /*
1118  * set up a private mapping or an anonymous shared mapping
1119  */
1120 static int do_mmap_private(struct vm_area_struct *vma,
1121                            struct vm_region *region,
1122                            unsigned long len,
1123                            unsigned long capabilities)
1124 {
1125         struct page *pages;
1126         unsigned long total, point, n;
1127         void *base;
1128         int ret, order;
1129
1130         /* invoke the file's mapping function so that it can keep track of
1131          * shared mappings on devices or memory
1132          * - VM_MAYSHARE will be set if it may attempt to share
1133          */
1134         if (capabilities & BDI_CAP_MAP_DIRECT) {
1135                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1136                 if (ret == 0) {
1137                         /* shouldn't return success if we're not sharing */
1138                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1139                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1140                         return 0;
1141                 }
1142                 if (ret != -ENOSYS)
1143                         return ret;
1144
1145                 /* getting an ENOSYS error indicates that direct mmap isn't
1146                  * possible (as opposed to tried but failed) so we'll try to
1147                  * make a private copy of the data and map that instead */
1148         }
1149
1150
1151         /* allocate some memory to hold the mapping
1152          * - note that this may not return a page-aligned address if the object
1153          *   we're allocating is smaller than a page
1154          */
1155         order = get_order(len);
1156         kdebug("alloc order %d for %lx", order, len);
1157
1158         pages = alloc_pages(GFP_KERNEL, order);
1159         if (!pages)
1160                 goto enomem;
1161
1162         total = 1 << order;
1163         atomic_long_add(total, &mmap_pages_allocated);
1164
1165         point = len >> PAGE_SHIFT;
1166
1167         /* we allocated a power-of-2 sized page set, so we may want to trim off
1168          * the excess */
1169         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1170                 while (total > point) {
1171                         order = ilog2(total - point);
1172                         n = 1 << order;
1173                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1174                         atomic_long_sub(n, &mmap_pages_allocated);
1175                         total -= n;
1176                         set_page_refcounted(pages + total);
1177                         __free_pages(pages + total, order);
1178                 }
1179         }
1180
1181         for (point = 1; point < total; point++)
1182                 set_page_refcounted(&pages[point]);
1183
1184         base = page_address(pages);
1185         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1186         region->vm_start = (unsigned long) base;
1187         region->vm_end   = region->vm_start + len;
1188         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1189
1190         vma->vm_start = region->vm_start;
1191         vma->vm_end   = region->vm_start + len;
1192
1193         if (vma->vm_file) {
1194                 /* read the contents of a file into the copy */
1195                 mm_segment_t old_fs;
1196                 loff_t fpos;
1197
1198                 fpos = vma->vm_pgoff;
1199                 fpos <<= PAGE_SHIFT;
1200
1201                 old_fs = get_fs();
1202                 set_fs(KERNEL_DS);
1203                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1204                 set_fs(old_fs);
1205
1206                 if (ret < 0)
1207                         goto error_free;
1208
1209                 /* clear the last little bit */
1210                 if (ret < len)
1211                         memset(base + ret, 0, len - ret);
1212
1213         }
1214
1215         return 0;
1216
1217 error_free:
1218         free_page_series(region->vm_start, region->vm_top);
1219         region->vm_start = vma->vm_start = 0;
1220         region->vm_end   = vma->vm_end = 0;
1221         region->vm_top   = 0;
1222         return ret;
1223
1224 enomem:
1225         printk("Allocation of length %lu from process %d (%s) failed\n",
1226                len, current->pid, current->comm);
1227         show_free_areas(0);
1228         return -ENOMEM;
1229 }
1230
1231 /*
1232  * handle mapping creation for uClinux
1233  */
1234 unsigned long do_mmap_pgoff(struct file *file,
1235                             unsigned long addr,
1236                             unsigned long len,
1237                             unsigned long prot,
1238                             unsigned long flags,
1239                             unsigned long pgoff)
1240 {
1241         struct vm_area_struct *vma;
1242         struct vm_region *region;
1243         struct rb_node *rb;
1244         unsigned long capabilities, vm_flags, result;
1245         int ret;
1246
1247         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1248
1249         /* decide whether we should attempt the mapping, and if so what sort of
1250          * mapping */
1251         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1252                                     &capabilities);
1253         if (ret < 0) {
1254                 kleave(" = %d [val]", ret);
1255                 return ret;
1256         }
1257
1258         /* we ignore the address hint */
1259         addr = 0;
1260         len = PAGE_ALIGN(len);
1261
1262         /* we've determined that we can make the mapping, now translate what we
1263          * now know into VMA flags */
1264         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1265
1266         /* we're going to need to record the mapping */
1267         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1268         if (!region)
1269                 goto error_getting_region;
1270
1271         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1272         if (!vma)
1273                 goto error_getting_vma;
1274
1275         region->vm_usage = 1;
1276         region->vm_flags = vm_flags;
1277         region->vm_pgoff = pgoff;
1278
1279         INIT_LIST_HEAD(&vma->anon_vma_chain);
1280         vma->vm_flags = vm_flags;
1281         vma->vm_pgoff = pgoff;
1282
1283         if (file) {
1284                 region->vm_file = file;
1285                 get_file(file);
1286                 vma->vm_file = file;
1287                 get_file(file);
1288                 if (vm_flags & VM_EXECUTABLE) {
1289                         added_exe_file_vma(current->mm);
1290                         vma->vm_mm = current->mm;
1291                 }
1292         }
1293
1294         down_write(&nommu_region_sem);
1295
1296         /* if we want to share, we need to check for regions created by other
1297          * mmap() calls that overlap with our proposed mapping
1298          * - we can only share with a superset match on most regular files
1299          * - shared mappings on character devices and memory backed files are
1300          *   permitted to overlap inexactly as far as we are concerned for in
1301          *   these cases, sharing is handled in the driver or filesystem rather
1302          *   than here
1303          */
1304         if (vm_flags & VM_MAYSHARE) {
1305                 struct vm_region *pregion;
1306                 unsigned long pglen, rpglen, pgend, rpgend, start;
1307
1308                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1309                 pgend = pgoff + pglen;
1310
1311                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1312                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1313
1314                         if (!(pregion->vm_flags & VM_MAYSHARE))
1315                                 continue;
1316
1317                         /* search for overlapping mappings on the same file */
1318                         if (pregion->vm_file->f_path.dentry->d_inode !=
1319                             file->f_path.dentry->d_inode)
1320                                 continue;
1321
1322                         if (pregion->vm_pgoff >= pgend)
1323                                 continue;
1324
1325                         rpglen = pregion->vm_end - pregion->vm_start;
1326                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1327                         rpgend = pregion->vm_pgoff + rpglen;
1328                         if (pgoff >= rpgend)
1329                                 continue;
1330
1331                         /* handle inexactly overlapping matches between
1332                          * mappings */
1333                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1334                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1335                                 /* new mapping is not a subset of the region */
1336                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1337                                         goto sharing_violation;
1338                                 continue;
1339                         }
1340
1341                         /* we've found a region we can share */
1342                         pregion->vm_usage++;
1343                         vma->vm_region = pregion;
1344                         start = pregion->vm_start;
1345                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1346                         vma->vm_start = start;
1347                         vma->vm_end = start + len;
1348
1349                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1350                                 kdebug("share copy");
1351                                 vma->vm_flags |= VM_MAPPED_COPY;
1352                         } else {
1353                                 kdebug("share mmap");
1354                                 ret = do_mmap_shared_file(vma);
1355                                 if (ret < 0) {
1356                                         vma->vm_region = NULL;
1357                                         vma->vm_start = 0;
1358                                         vma->vm_end = 0;
1359                                         pregion->vm_usage--;
1360                                         pregion = NULL;
1361                                         goto error_just_free;
1362                                 }
1363                         }
1364                         fput(region->vm_file);
1365                         kmem_cache_free(vm_region_jar, region);
1366                         region = pregion;
1367                         result = start;
1368                         goto share;
1369                 }
1370
1371                 /* obtain the address at which to make a shared mapping
1372                  * - this is the hook for quasi-memory character devices to
1373                  *   tell us the location of a shared mapping
1374                  */
1375                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1376                         addr = file->f_op->get_unmapped_area(file, addr, len,
1377                                                              pgoff, flags);
1378                         if (IS_ERR_VALUE(addr)) {
1379                                 ret = addr;
1380                                 if (ret != -ENOSYS)
1381                                         goto error_just_free;
1382
1383                                 /* the driver refused to tell us where to site
1384                                  * the mapping so we'll have to attempt to copy
1385                                  * it */
1386                                 ret = -ENODEV;
1387                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1388                                         goto error_just_free;
1389
1390                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1391                         } else {
1392                                 vma->vm_start = region->vm_start = addr;
1393                                 vma->vm_end = region->vm_end = addr + len;
1394                         }
1395                 }
1396         }
1397
1398         vma->vm_region = region;
1399
1400         /* set up the mapping
1401          * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1402          */
1403         if (file && vma->vm_flags & VM_SHARED)
1404                 ret = do_mmap_shared_file(vma);
1405         else
1406                 ret = do_mmap_private(vma, region, len, capabilities);
1407         if (ret < 0)
1408                 goto error_just_free;
1409         add_nommu_region(region);
1410
1411         /* clear anonymous mappings that don't ask for uninitialized data */
1412         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1413                 memset((void *)region->vm_start, 0,
1414                        region->vm_end - region->vm_start);
1415
1416         /* okay... we have a mapping; now we have to register it */
1417         result = vma->vm_start;
1418
1419         current->mm->total_vm += len >> PAGE_SHIFT;
1420
1421 share:
1422         add_vma_to_mm(current->mm, vma);
1423
1424         /* we flush the region from the icache only when the first executable
1425          * mapping of it is made  */
1426         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1427                 flush_icache_range(region->vm_start, region->vm_end);
1428                 region->vm_icache_flushed = true;
1429         }
1430
1431         up_write(&nommu_region_sem);
1432
1433         kleave(" = %lx", result);
1434         return result;
1435
1436 error_just_free:
1437         up_write(&nommu_region_sem);
1438 error:
1439         if (region->vm_file)
1440                 fput(region->vm_file);
1441         kmem_cache_free(vm_region_jar, region);
1442         if (vma->vm_file)
1443                 fput(vma->vm_file);
1444         if (vma->vm_flags & VM_EXECUTABLE)
1445                 removed_exe_file_vma(vma->vm_mm);
1446         kmem_cache_free(vm_area_cachep, vma);
1447         kleave(" = %d", ret);
1448         return ret;
1449
1450 sharing_violation:
1451         up_write(&nommu_region_sem);
1452         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1453         ret = -EINVAL;
1454         goto error;
1455
1456 error_getting_vma:
1457         kmem_cache_free(vm_region_jar, region);
1458         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1459                " from process %d failed\n",
1460                len, current->pid);
1461         show_free_areas(0);
1462         return -ENOMEM;
1463
1464 error_getting_region:
1465         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1466                " from process %d failed\n",
1467                len, current->pid);
1468         show_free_areas(0);
1469         return -ENOMEM;
1470 }
1471 EXPORT_SYMBOL(do_mmap_pgoff);
1472
1473 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1474                 unsigned long, prot, unsigned long, flags,
1475                 unsigned long, fd, unsigned long, pgoff)
1476 {
1477         struct file *file = NULL;
1478         unsigned long retval = -EBADF;
1479
1480         audit_mmap_fd(fd, flags);
1481         if (!(flags & MAP_ANONYMOUS)) {
1482                 file = fget(fd);
1483                 if (!file)
1484                         goto out;
1485         }
1486
1487         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1488
1489         down_write(&current->mm->mmap_sem);
1490         retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1491         up_write(&current->mm->mmap_sem);
1492
1493         if (file)
1494                 fput(file);
1495 out:
1496         return retval;
1497 }
1498
1499 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1500 struct mmap_arg_struct {
1501         unsigned long addr;
1502         unsigned long len;
1503         unsigned long prot;
1504         unsigned long flags;
1505         unsigned long fd;
1506         unsigned long offset;
1507 };
1508
1509 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1510 {
1511         struct mmap_arg_struct a;
1512
1513         if (copy_from_user(&a, arg, sizeof(a)))
1514                 return -EFAULT;
1515         if (a.offset & ~PAGE_MASK)
1516                 return -EINVAL;
1517
1518         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1519                               a.offset >> PAGE_SHIFT);
1520 }
1521 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1522
1523 /*
1524  * split a vma into two pieces at address 'addr', a new vma is allocated either
1525  * for the first part or the tail.
1526  */
1527 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1528               unsigned long addr, int new_below)
1529 {
1530         struct vm_area_struct *new;
1531         struct vm_region *region;
1532         unsigned long npages;
1533
1534         kenter("");
1535
1536         /* we're only permitted to split anonymous regions (these should have
1537          * only a single usage on the region) */
1538         if (vma->vm_file)
1539                 return -ENOMEM;
1540
1541         if (mm->map_count >= sysctl_max_map_count)
1542                 return -ENOMEM;
1543
1544         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1545         if (!region)
1546                 return -ENOMEM;
1547
1548         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1549         if (!new) {
1550                 kmem_cache_free(vm_region_jar, region);
1551                 return -ENOMEM;
1552         }
1553
1554         /* most fields are the same, copy all, and then fixup */
1555         *new = *vma;
1556         *region = *vma->vm_region;
1557         new->vm_region = region;
1558
1559         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1560
1561         if (new_below) {
1562                 region->vm_top = region->vm_end = new->vm_end = addr;
1563         } else {
1564                 region->vm_start = new->vm_start = addr;
1565                 region->vm_pgoff = new->vm_pgoff += npages;
1566         }
1567
1568         if (new->vm_ops && new->vm_ops->open)
1569                 new->vm_ops->open(new);
1570
1571         delete_vma_from_mm(vma);
1572         down_write(&nommu_region_sem);
1573         delete_nommu_region(vma->vm_region);
1574         if (new_below) {
1575                 vma->vm_region->vm_start = vma->vm_start = addr;
1576                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1577         } else {
1578                 vma->vm_region->vm_end = vma->vm_end = addr;
1579                 vma->vm_region->vm_top = addr;
1580         }
1581         add_nommu_region(vma->vm_region);
1582         add_nommu_region(new->vm_region);
1583         up_write(&nommu_region_sem);
1584         add_vma_to_mm(mm, vma);
1585         add_vma_to_mm(mm, new);
1586         return 0;
1587 }
1588
1589 /*
1590  * shrink a VMA by removing the specified chunk from either the beginning or
1591  * the end
1592  */
1593 static int shrink_vma(struct mm_struct *mm,
1594                       struct vm_area_struct *vma,
1595                       unsigned long from, unsigned long to)
1596 {
1597         struct vm_region *region;
1598
1599         kenter("");
1600
1601         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1602          * and list */
1603         delete_vma_from_mm(vma);
1604         if (from > vma->vm_start)
1605                 vma->vm_end = from;
1606         else
1607                 vma->vm_start = to;
1608         add_vma_to_mm(mm, vma);
1609
1610         /* cut the backing region down to size */
1611         region = vma->vm_region;
1612         BUG_ON(region->vm_usage != 1);
1613
1614         down_write(&nommu_region_sem);
1615         delete_nommu_region(region);
1616         if (from > region->vm_start) {
1617                 to = region->vm_top;
1618                 region->vm_top = region->vm_end = from;
1619         } else {
1620                 region->vm_start = to;
1621         }
1622         add_nommu_region(region);
1623         up_write(&nommu_region_sem);
1624
1625         free_page_series(from, to);
1626         return 0;
1627 }
1628
1629 /*
1630  * release a mapping
1631  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1632  *   VMA, though it need not cover the whole VMA
1633  */
1634 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1635 {
1636         struct vm_area_struct *vma;
1637         unsigned long end;
1638         int ret;
1639
1640         kenter(",%lx,%zx", start, len);
1641
1642         len = PAGE_ALIGN(len);
1643         if (len == 0)
1644                 return -EINVAL;
1645
1646         end = start + len;
1647
1648         /* find the first potentially overlapping VMA */
1649         vma = find_vma(mm, start);
1650         if (!vma) {
1651                 static int limit = 0;
1652                 if (limit < 5) {
1653                         printk(KERN_WARNING
1654                                "munmap of memory not mmapped by process %d"
1655                                " (%s): 0x%lx-0x%lx\n",
1656                                current->pid, current->comm,
1657                                start, start + len - 1);
1658                         limit++;
1659                 }
1660                 return -EINVAL;
1661         }
1662
1663         /* we're allowed to split an anonymous VMA but not a file-backed one */
1664         if (vma->vm_file) {
1665                 do {
1666                         if (start > vma->vm_start) {
1667                                 kleave(" = -EINVAL [miss]");
1668                                 return -EINVAL;
1669                         }
1670                         if (end == vma->vm_end)
1671                                 goto erase_whole_vma;
1672                         vma = vma->vm_next;
1673                 } while (vma);
1674                 kleave(" = -EINVAL [split file]");
1675                 return -EINVAL;
1676         } else {
1677                 /* the chunk must be a subset of the VMA found */
1678                 if (start == vma->vm_start && end == vma->vm_end)
1679                         goto erase_whole_vma;
1680                 if (start < vma->vm_start || end > vma->vm_end) {
1681                         kleave(" = -EINVAL [superset]");
1682                         return -EINVAL;
1683                 }
1684                 if (start & ~PAGE_MASK) {
1685                         kleave(" = -EINVAL [unaligned start]");
1686                         return -EINVAL;
1687                 }
1688                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1689                         kleave(" = -EINVAL [unaligned split]");
1690                         return -EINVAL;
1691                 }
1692                 if (start != vma->vm_start && end != vma->vm_end) {
1693                         ret = split_vma(mm, vma, start, 1);
1694                         if (ret < 0) {
1695                                 kleave(" = %d [split]", ret);
1696                                 return ret;
1697                         }
1698                 }
1699                 return shrink_vma(mm, vma, start, end);
1700         }
1701
1702 erase_whole_vma:
1703         delete_vma_from_mm(vma);
1704         delete_vma(mm, vma);
1705         kleave(" = 0");
1706         return 0;
1707 }
1708 EXPORT_SYMBOL(do_munmap);
1709
1710 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1711 {
1712         int ret;
1713         struct mm_struct *mm = current->mm;
1714
1715         down_write(&mm->mmap_sem);
1716         ret = do_munmap(mm, addr, len);
1717         up_write(&mm->mmap_sem);
1718         return ret;
1719 }
1720
1721 /*
1722  * release all the mappings made in a process's VM space
1723  */
1724 void exit_mmap(struct mm_struct *mm)
1725 {
1726         struct vm_area_struct *vma;
1727
1728         if (!mm)
1729                 return;
1730
1731         kenter("");
1732
1733         mm->total_vm = 0;
1734
1735         while ((vma = mm->mmap)) {
1736                 mm->mmap = vma->vm_next;
1737                 delete_vma_from_mm(vma);
1738                 delete_vma(mm, vma);
1739                 cond_resched();
1740         }
1741
1742         kleave("");
1743 }
1744
1745 unsigned long do_brk(unsigned long addr, unsigned long len)
1746 {
1747         return -ENOMEM;
1748 }
1749
1750 /*
1751  * expand (or shrink) an existing mapping, potentially moving it at the same
1752  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1753  *
1754  * under NOMMU conditions, we only permit changing a mapping's size, and only
1755  * as long as it stays within the region allocated by do_mmap_private() and the
1756  * block is not shareable
1757  *
1758  * MREMAP_FIXED is not supported under NOMMU conditions
1759  */
1760 unsigned long do_mremap(unsigned long addr,
1761                         unsigned long old_len, unsigned long new_len,
1762                         unsigned long flags, unsigned long new_addr)
1763 {
1764         struct vm_area_struct *vma;
1765
1766         /* insanity checks first */
1767         old_len = PAGE_ALIGN(old_len);
1768         new_len = PAGE_ALIGN(new_len);
1769         if (old_len == 0 || new_len == 0)
1770                 return (unsigned long) -EINVAL;
1771
1772         if (addr & ~PAGE_MASK)
1773                 return -EINVAL;
1774
1775         if (flags & MREMAP_FIXED && new_addr != addr)
1776                 return (unsigned long) -EINVAL;
1777
1778         vma = find_vma_exact(current->mm, addr, old_len);
1779         if (!vma)
1780                 return (unsigned long) -EINVAL;
1781
1782         if (vma->vm_end != vma->vm_start + old_len)
1783                 return (unsigned long) -EFAULT;
1784
1785         if (vma->vm_flags & VM_MAYSHARE)
1786                 return (unsigned long) -EPERM;
1787
1788         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1789                 return (unsigned long) -ENOMEM;
1790
1791         /* all checks complete - do it */
1792         vma->vm_end = vma->vm_start + new_len;
1793         return vma->vm_start;
1794 }
1795 EXPORT_SYMBOL(do_mremap);
1796
1797 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1798                 unsigned long, new_len, unsigned long, flags,
1799                 unsigned long, new_addr)
1800 {
1801         unsigned long ret;
1802
1803         down_write(&current->mm->mmap_sem);
1804         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1805         up_write(&current->mm->mmap_sem);
1806         return ret;
1807 }
1808
1809 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1810                         unsigned int foll_flags)
1811 {
1812         return NULL;
1813 }
1814
1815 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1816                 unsigned long pfn, unsigned long size, pgprot_t prot)
1817 {
1818         if (addr != (pfn << PAGE_SHIFT))
1819                 return -EINVAL;
1820
1821         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1822         return 0;
1823 }
1824 EXPORT_SYMBOL(remap_pfn_range);
1825
1826 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1827                         unsigned long pgoff)
1828 {
1829         unsigned int size = vma->vm_end - vma->vm_start;
1830
1831         if (!(vma->vm_flags & VM_USERMAP))
1832                 return -EINVAL;
1833
1834         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1835         vma->vm_end = vma->vm_start + size;
1836
1837         return 0;
1838 }
1839 EXPORT_SYMBOL(remap_vmalloc_range);
1840
1841 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1842         unsigned long len, unsigned long pgoff, unsigned long flags)
1843 {
1844         return -ENOMEM;
1845 }
1846
1847 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1848 {
1849 }
1850
1851 void unmap_mapping_range(struct address_space *mapping,
1852                          loff_t const holebegin, loff_t const holelen,
1853                          int even_cows)
1854 {
1855 }
1856 EXPORT_SYMBOL(unmap_mapping_range);
1857
1858 /*
1859  * Check that a process has enough memory to allocate a new virtual
1860  * mapping. 0 means there is enough memory for the allocation to
1861  * succeed and -ENOMEM implies there is not.
1862  *
1863  * We currently support three overcommit policies, which are set via the
1864  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1865  *
1866  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1867  * Additional code 2002 Jul 20 by Robert Love.
1868  *
1869  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1870  *
1871  * Note this is a helper function intended to be used by LSMs which
1872  * wish to use this logic.
1873  */
1874 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1875 {
1876         unsigned long free, allowed;
1877
1878         vm_acct_memory(pages);
1879
1880         /*
1881          * Sometimes we want to use more memory than we have
1882          */
1883         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1884                 return 0;
1885
1886         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1887                 free = global_page_state(NR_FREE_PAGES);
1888                 free += global_page_state(NR_FILE_PAGES);
1889
1890                 /*
1891                  * shmem pages shouldn't be counted as free in this
1892                  * case, they can't be purged, only swapped out, and
1893                  * that won't affect the overall amount of available
1894                  * memory in the system.
1895                  */
1896                 free -= global_page_state(NR_SHMEM);
1897
1898                 free += nr_swap_pages;
1899
1900                 /*
1901                  * Any slabs which are created with the
1902                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1903                  * which are reclaimable, under pressure.  The dentry
1904                  * cache and most inode caches should fall into this
1905                  */
1906                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1907
1908                 /*
1909                  * Leave reserved pages. The pages are not for anonymous pages.
1910                  */
1911                 if (free <= totalreserve_pages)
1912                         goto error;
1913                 else
1914                         free -= totalreserve_pages;
1915
1916                 /*
1917                  * Leave the last 3% for root
1918                  */
1919                 if (!cap_sys_admin)
1920                         free -= free / 32;
1921
1922                 if (free > pages)
1923                         return 0;
1924
1925                 goto error;
1926         }
1927
1928         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1929         /*
1930          * Leave the last 3% for root
1931          */
1932         if (!cap_sys_admin)
1933                 allowed -= allowed / 32;
1934         allowed += total_swap_pages;
1935
1936         /* Don't let a single process grow too big:
1937            leave 3% of the size of this process for other processes */
1938         if (mm)
1939                 allowed -= mm->total_vm / 32;
1940
1941         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1942                 return 0;
1943
1944 error:
1945         vm_unacct_memory(pages);
1946
1947         return -ENOMEM;
1948 }
1949
1950 int in_gate_area_no_mm(unsigned long addr)
1951 {
1952         return 0;
1953 }
1954
1955 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1956 {
1957         BUG();
1958         return 0;
1959 }
1960 EXPORT_SYMBOL(filemap_fault);
1961
1962 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1963                 unsigned long addr, void *buf, int len, int write)
1964 {
1965         struct vm_area_struct *vma;
1966
1967         down_read(&mm->mmap_sem);
1968
1969         /* the access must start within one of the target process's mappings */
1970         vma = find_vma(mm, addr);
1971         if (vma) {
1972                 /* don't overrun this mapping */
1973                 if (addr + len >= vma->vm_end)
1974                         len = vma->vm_end - addr;
1975
1976                 /* only read or write mappings where it is permitted */
1977                 if (write && vma->vm_flags & VM_MAYWRITE)
1978                         copy_to_user_page(vma, NULL, addr,
1979                                          (void *) addr, buf, len);
1980                 else if (!write && vma->vm_flags & VM_MAYREAD)
1981                         copy_from_user_page(vma, NULL, addr,
1982                                             buf, (void *) addr, len);
1983                 else
1984                         len = 0;
1985         } else {
1986                 len = 0;
1987         }
1988
1989         up_read(&mm->mmap_sem);
1990
1991         return len;
1992 }
1993
1994 /**
1995  * @access_remote_vm - access another process' address space
1996  * @mm:         the mm_struct of the target address space
1997  * @addr:       start address to access
1998  * @buf:        source or destination buffer
1999  * @len:        number of bytes to transfer
2000  * @write:      whether the access is a write
2001  *
2002  * The caller must hold a reference on @mm.
2003  */
2004 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2005                 void *buf, int len, int write)
2006 {
2007         return __access_remote_vm(NULL, mm, addr, buf, len, write);
2008 }
2009
2010 /*
2011  * Access another process' address space.
2012  * - source/target buffer must be kernel space
2013  */
2014 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2015 {
2016         struct mm_struct *mm;
2017
2018         if (addr + len < addr)
2019                 return 0;
2020
2021         mm = get_task_mm(tsk);
2022         if (!mm)
2023                 return 0;
2024
2025         len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2026
2027         mmput(mm);
2028         return len;
2029 }
2030
2031 /**
2032  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2033  * @inode: The inode to check
2034  * @size: The current filesize of the inode
2035  * @newsize: The proposed filesize of the inode
2036  *
2037  * Check the shared mappings on an inode on behalf of a shrinking truncate to
2038  * make sure that that any outstanding VMAs aren't broken and then shrink the
2039  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2040  * automatically grant mappings that are too large.
2041  */
2042 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2043                                 size_t newsize)
2044 {
2045         struct vm_area_struct *vma;
2046         struct prio_tree_iter iter;
2047         struct vm_region *region;
2048         pgoff_t low, high;
2049         size_t r_size, r_top;
2050
2051         low = newsize >> PAGE_SHIFT;
2052         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2053
2054         down_write(&nommu_region_sem);
2055
2056         /* search for VMAs that fall within the dead zone */
2057         vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2058                               low, high) {
2059                 /* found one - only interested if it's shared out of the page
2060                  * cache */
2061                 if (vma->vm_flags & VM_SHARED) {
2062                         up_write(&nommu_region_sem);
2063                         return -ETXTBSY; /* not quite true, but near enough */
2064                 }
2065         }
2066
2067         /* reduce any regions that overlap the dead zone - if in existence,
2068          * these will be pointed to by VMAs that don't overlap the dead zone
2069          *
2070          * we don't check for any regions that start beyond the EOF as there
2071          * shouldn't be any
2072          */
2073         vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2074                               0, ULONG_MAX) {
2075                 if (!(vma->vm_flags & VM_SHARED))
2076                         continue;
2077
2078                 region = vma->vm_region;
2079                 r_size = region->vm_top - region->vm_start;
2080                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2081
2082                 if (r_top > newsize) {
2083                         region->vm_top -= r_top - newsize;
2084                         if (region->vm_end > region->vm_top)
2085                                 region->vm_end = region->vm_top;
2086                 }
2087         }
2088
2089         up_write(&nommu_region_sem);
2090         return 0;
2091 }