Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
[platform/adaptation/renesas_rcar/renesas_kernel.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/export.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 #include <linux/sched/sysctl.h>
33
34 #include <asm/uaccess.h>
35 #include <asm/tlb.h>
36 #include <asm/tlbflush.h>
37 #include <asm/mmu_context.h>
38 #include "internal.h"
39
40 #if 0
41 #define kenter(FMT, ...) \
42         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
43 #define kleave(FMT, ...) \
44         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
45 #define kdebug(FMT, ...) \
46         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
47 #else
48 #define kenter(FMT, ...) \
49         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
50 #define kleave(FMT, ...) \
51         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
52 #define kdebug(FMT, ...) \
53         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
54 #endif
55
56 void *high_memory;
57 struct page *mem_map;
58 unsigned long max_mapnr;
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 unsigned long sysctl_overcommit_kbytes __read_mostly;
64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
65 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
66 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
67 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
68 int heap_stack_gap = 0;
69
70 atomic_long_t mmap_pages_allocated;
71
72 /*
73  * The global memory commitment made in the system can be a metric
74  * that can be used to drive ballooning decisions when Linux is hosted
75  * as a guest. On Hyper-V, the host implements a policy engine for dynamically
76  * balancing memory across competing virtual machines that are hosted.
77  * Several metrics drive this policy engine including the guest reported
78  * memory commitment.
79  */
80 unsigned long vm_memory_committed(void)
81 {
82         return percpu_counter_read_positive(&vm_committed_as);
83 }
84
85 EXPORT_SYMBOL_GPL(vm_memory_committed);
86
87 EXPORT_SYMBOL(mem_map);
88
89 /* list of mapped, potentially shareable regions */
90 static struct kmem_cache *vm_region_jar;
91 struct rb_root nommu_region_tree = RB_ROOT;
92 DECLARE_RWSEM(nommu_region_sem);
93
94 const struct vm_operations_struct generic_file_vm_ops = {
95 };
96
97 /*
98  * Return the total memory allocated for this pointer, not
99  * just what the caller asked for.
100  *
101  * Doesn't have to be accurate, i.e. may have races.
102  */
103 unsigned int kobjsize(const void *objp)
104 {
105         struct page *page;
106
107         /*
108          * If the object we have should not have ksize performed on it,
109          * return size of 0
110          */
111         if (!objp || !virt_addr_valid(objp))
112                 return 0;
113
114         page = virt_to_head_page(objp);
115
116         /*
117          * If the allocator sets PageSlab, we know the pointer came from
118          * kmalloc().
119          */
120         if (PageSlab(page))
121                 return ksize(objp);
122
123         /*
124          * If it's not a compound page, see if we have a matching VMA
125          * region. This test is intentionally done in reverse order,
126          * so if there's no VMA, we still fall through and hand back
127          * PAGE_SIZE for 0-order pages.
128          */
129         if (!PageCompound(page)) {
130                 struct vm_area_struct *vma;
131
132                 vma = find_vma(current->mm, (unsigned long)objp);
133                 if (vma)
134                         return vma->vm_end - vma->vm_start;
135         }
136
137         /*
138          * The ksize() function is only guaranteed to work for pointers
139          * returned by kmalloc(). So handle arbitrary pointers here.
140          */
141         return PAGE_SIZE << compound_order(page);
142 }
143
144 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
145                       unsigned long start, unsigned long nr_pages,
146                       unsigned int foll_flags, struct page **pages,
147                       struct vm_area_struct **vmas, int *nonblocking)
148 {
149         struct vm_area_struct *vma;
150         unsigned long vm_flags;
151         int i;
152
153         /* calculate required read or write permissions.
154          * If FOLL_FORCE is set, we only require the "MAY" flags.
155          */
156         vm_flags  = (foll_flags & FOLL_WRITE) ?
157                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
158         vm_flags &= (foll_flags & FOLL_FORCE) ?
159                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
160
161         for (i = 0; i < nr_pages; i++) {
162                 vma = find_vma(mm, start);
163                 if (!vma)
164                         goto finish_or_fault;
165
166                 /* protect what we can, including chardevs */
167                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
168                     !(vm_flags & vma->vm_flags))
169                         goto finish_or_fault;
170
171                 if (pages) {
172                         pages[i] = virt_to_page(start);
173                         if (pages[i])
174                                 page_cache_get(pages[i]);
175                 }
176                 if (vmas)
177                         vmas[i] = vma;
178                 start = (start + PAGE_SIZE) & PAGE_MASK;
179         }
180
181         return i;
182
183 finish_or_fault:
184         return i ? : -EFAULT;
185 }
186
187 /*
188  * get a list of pages in an address range belonging to the specified process
189  * and indicate the VMA that covers each page
190  * - this is potentially dodgy as we may end incrementing the page count of a
191  *   slab page or a secondary page from a compound page
192  * - don't permit access to VMAs that don't support it, such as I/O mappings
193  */
194 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
195                     unsigned long start, unsigned long nr_pages,
196                     int write, int force, struct page **pages,
197                     struct vm_area_struct **vmas)
198 {
199         int flags = 0;
200
201         if (write)
202                 flags |= FOLL_WRITE;
203         if (force)
204                 flags |= FOLL_FORCE;
205
206         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
207                                 NULL);
208 }
209 EXPORT_SYMBOL(get_user_pages);
210
211 /**
212  * follow_pfn - look up PFN at a user virtual address
213  * @vma: memory mapping
214  * @address: user virtual address
215  * @pfn: location to store found PFN
216  *
217  * Only IO mappings and raw PFN mappings are allowed.
218  *
219  * Returns zero and the pfn at @pfn on success, -ve otherwise.
220  */
221 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
222         unsigned long *pfn)
223 {
224         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
225                 return -EINVAL;
226
227         *pfn = address >> PAGE_SHIFT;
228         return 0;
229 }
230 EXPORT_SYMBOL(follow_pfn);
231
232 LIST_HEAD(vmap_area_list);
233
234 void vfree(const void *addr)
235 {
236         kfree(addr);
237 }
238 EXPORT_SYMBOL(vfree);
239
240 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
241 {
242         /*
243          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
244          * returns only a logical address.
245          */
246         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
247 }
248 EXPORT_SYMBOL(__vmalloc);
249
250 void *vmalloc_user(unsigned long size)
251 {
252         void *ret;
253
254         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
255                         PAGE_KERNEL);
256         if (ret) {
257                 struct vm_area_struct *vma;
258
259                 down_write(&current->mm->mmap_sem);
260                 vma = find_vma(current->mm, (unsigned long)ret);
261                 if (vma)
262                         vma->vm_flags |= VM_USERMAP;
263                 up_write(&current->mm->mmap_sem);
264         }
265
266         return ret;
267 }
268 EXPORT_SYMBOL(vmalloc_user);
269
270 struct page *vmalloc_to_page(const void *addr)
271 {
272         return virt_to_page(addr);
273 }
274 EXPORT_SYMBOL(vmalloc_to_page);
275
276 unsigned long vmalloc_to_pfn(const void *addr)
277 {
278         return page_to_pfn(virt_to_page(addr));
279 }
280 EXPORT_SYMBOL(vmalloc_to_pfn);
281
282 long vread(char *buf, char *addr, unsigned long count)
283 {
284         /* Don't allow overflow */
285         if ((unsigned long) buf + count < count)
286                 count = -(unsigned long) buf;
287
288         memcpy(buf, addr, count);
289         return count;
290 }
291
292 long vwrite(char *buf, char *addr, unsigned long count)
293 {
294         /* Don't allow overflow */
295         if ((unsigned long) addr + count < count)
296                 count = -(unsigned long) addr;
297
298         memcpy(addr, buf, count);
299         return(count);
300 }
301
302 /*
303  *      vmalloc  -  allocate virtually continguos memory
304  *
305  *      @size:          allocation size
306  *
307  *      Allocate enough pages to cover @size from the page level
308  *      allocator and map them into continguos kernel virtual space.
309  *
310  *      For tight control over page level allocator and protection flags
311  *      use __vmalloc() instead.
312  */
313 void *vmalloc(unsigned long size)
314 {
315        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
316 }
317 EXPORT_SYMBOL(vmalloc);
318
319 /*
320  *      vzalloc - allocate virtually continguos memory with zero fill
321  *
322  *      @size:          allocation size
323  *
324  *      Allocate enough pages to cover @size from the page level
325  *      allocator and map them into continguos kernel virtual space.
326  *      The memory allocated is set to zero.
327  *
328  *      For tight control over page level allocator and protection flags
329  *      use __vmalloc() instead.
330  */
331 void *vzalloc(unsigned long size)
332 {
333         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
334                         PAGE_KERNEL);
335 }
336 EXPORT_SYMBOL(vzalloc);
337
338 /**
339  * vmalloc_node - allocate memory on a specific node
340  * @size:       allocation size
341  * @node:       numa node
342  *
343  * Allocate enough pages to cover @size from the page level
344  * allocator and map them into contiguous kernel virtual space.
345  *
346  * For tight control over page level allocator and protection flags
347  * use __vmalloc() instead.
348  */
349 void *vmalloc_node(unsigned long size, int node)
350 {
351         return vmalloc(size);
352 }
353 EXPORT_SYMBOL(vmalloc_node);
354
355 /**
356  * vzalloc_node - allocate memory on a specific node with zero fill
357  * @size:       allocation size
358  * @node:       numa node
359  *
360  * Allocate enough pages to cover @size from the page level
361  * allocator and map them into contiguous kernel virtual space.
362  * The memory allocated is set to zero.
363  *
364  * For tight control over page level allocator and protection flags
365  * use __vmalloc() instead.
366  */
367 void *vzalloc_node(unsigned long size, int node)
368 {
369         return vzalloc(size);
370 }
371 EXPORT_SYMBOL(vzalloc_node);
372
373 #ifndef PAGE_KERNEL_EXEC
374 # define PAGE_KERNEL_EXEC PAGE_KERNEL
375 #endif
376
377 /**
378  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
379  *      @size:          allocation size
380  *
381  *      Kernel-internal function to allocate enough pages to cover @size
382  *      the page level allocator and map them into contiguous and
383  *      executable kernel virtual space.
384  *
385  *      For tight control over page level allocator and protection flags
386  *      use __vmalloc() instead.
387  */
388
389 void *vmalloc_exec(unsigned long size)
390 {
391         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
392 }
393
394 /**
395  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
396  *      @size:          allocation size
397  *
398  *      Allocate enough 32bit PA addressable pages to cover @size from the
399  *      page level allocator and map them into continguos kernel virtual space.
400  */
401 void *vmalloc_32(unsigned long size)
402 {
403         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
404 }
405 EXPORT_SYMBOL(vmalloc_32);
406
407 /**
408  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
409  *      @size:          allocation size
410  *
411  * The resulting memory area is 32bit addressable and zeroed so it can be
412  * mapped to userspace without leaking data.
413  *
414  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
415  * remap_vmalloc_range() are permissible.
416  */
417 void *vmalloc_32_user(unsigned long size)
418 {
419         /*
420          * We'll have to sort out the ZONE_DMA bits for 64-bit,
421          * but for now this can simply use vmalloc_user() directly.
422          */
423         return vmalloc_user(size);
424 }
425 EXPORT_SYMBOL(vmalloc_32_user);
426
427 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
428 {
429         BUG();
430         return NULL;
431 }
432 EXPORT_SYMBOL(vmap);
433
434 void vunmap(const void *addr)
435 {
436         BUG();
437 }
438 EXPORT_SYMBOL(vunmap);
439
440 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
441 {
442         BUG();
443         return NULL;
444 }
445 EXPORT_SYMBOL(vm_map_ram);
446
447 void vm_unmap_ram(const void *mem, unsigned int count)
448 {
449         BUG();
450 }
451 EXPORT_SYMBOL(vm_unmap_ram);
452
453 void vm_unmap_aliases(void)
454 {
455 }
456 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
457
458 /*
459  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
460  * have one.
461  */
462 void  __attribute__((weak)) vmalloc_sync_all(void)
463 {
464 }
465
466 /**
467  *      alloc_vm_area - allocate a range of kernel address space
468  *      @size:          size of the area
469  *
470  *      Returns:        NULL on failure, vm_struct on success
471  *
472  *      This function reserves a range of kernel address space, and
473  *      allocates pagetables to map that range.  No actual mappings
474  *      are created.  If the kernel address space is not shared
475  *      between processes, it syncs the pagetable across all
476  *      processes.
477  */
478 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
479 {
480         BUG();
481         return NULL;
482 }
483 EXPORT_SYMBOL_GPL(alloc_vm_area);
484
485 void free_vm_area(struct vm_struct *area)
486 {
487         BUG();
488 }
489 EXPORT_SYMBOL_GPL(free_vm_area);
490
491 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
492                    struct page *page)
493 {
494         return -EINVAL;
495 }
496 EXPORT_SYMBOL(vm_insert_page);
497
498 /*
499  *  sys_brk() for the most part doesn't need the global kernel
500  *  lock, except when an application is doing something nasty
501  *  like trying to un-brk an area that has already been mapped
502  *  to a regular file.  in this case, the unmapping will need
503  *  to invoke file system routines that need the global lock.
504  */
505 SYSCALL_DEFINE1(brk, unsigned long, brk)
506 {
507         struct mm_struct *mm = current->mm;
508
509         if (brk < mm->start_brk || brk > mm->context.end_brk)
510                 return mm->brk;
511
512         if (mm->brk == brk)
513                 return mm->brk;
514
515         /*
516          * Always allow shrinking brk
517          */
518         if (brk <= mm->brk) {
519                 mm->brk = brk;
520                 return brk;
521         }
522
523         /*
524          * Ok, looks good - let it rip.
525          */
526         flush_icache_range(mm->brk, brk);
527         return mm->brk = brk;
528 }
529
530 /*
531  * initialise the VMA and region record slabs
532  */
533 void __init mmap_init(void)
534 {
535         int ret;
536
537         ret = percpu_counter_init(&vm_committed_as, 0);
538         VM_BUG_ON(ret);
539         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
540 }
541
542 /*
543  * validate the region tree
544  * - the caller must hold the region lock
545  */
546 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
547 static noinline void validate_nommu_regions(void)
548 {
549         struct vm_region *region, *last;
550         struct rb_node *p, *lastp;
551
552         lastp = rb_first(&nommu_region_tree);
553         if (!lastp)
554                 return;
555
556         last = rb_entry(lastp, struct vm_region, vm_rb);
557         BUG_ON(unlikely(last->vm_end <= last->vm_start));
558         BUG_ON(unlikely(last->vm_top < last->vm_end));
559
560         while ((p = rb_next(lastp))) {
561                 region = rb_entry(p, struct vm_region, vm_rb);
562                 last = rb_entry(lastp, struct vm_region, vm_rb);
563
564                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
565                 BUG_ON(unlikely(region->vm_top < region->vm_end));
566                 BUG_ON(unlikely(region->vm_start < last->vm_top));
567
568                 lastp = p;
569         }
570 }
571 #else
572 static void validate_nommu_regions(void)
573 {
574 }
575 #endif
576
577 /*
578  * add a region into the global tree
579  */
580 static void add_nommu_region(struct vm_region *region)
581 {
582         struct vm_region *pregion;
583         struct rb_node **p, *parent;
584
585         validate_nommu_regions();
586
587         parent = NULL;
588         p = &nommu_region_tree.rb_node;
589         while (*p) {
590                 parent = *p;
591                 pregion = rb_entry(parent, struct vm_region, vm_rb);
592                 if (region->vm_start < pregion->vm_start)
593                         p = &(*p)->rb_left;
594                 else if (region->vm_start > pregion->vm_start)
595                         p = &(*p)->rb_right;
596                 else if (pregion == region)
597                         return;
598                 else
599                         BUG();
600         }
601
602         rb_link_node(&region->vm_rb, parent, p);
603         rb_insert_color(&region->vm_rb, &nommu_region_tree);
604
605         validate_nommu_regions();
606 }
607
608 /*
609  * delete a region from the global tree
610  */
611 static void delete_nommu_region(struct vm_region *region)
612 {
613         BUG_ON(!nommu_region_tree.rb_node);
614
615         validate_nommu_regions();
616         rb_erase(&region->vm_rb, &nommu_region_tree);
617         validate_nommu_regions();
618 }
619
620 /*
621  * free a contiguous series of pages
622  */
623 static void free_page_series(unsigned long from, unsigned long to)
624 {
625         for (; from < to; from += PAGE_SIZE) {
626                 struct page *page = virt_to_page(from);
627
628                 kdebug("- free %lx", from);
629                 atomic_long_dec(&mmap_pages_allocated);
630                 if (page_count(page) != 1)
631                         kdebug("free page %p: refcount not one: %d",
632                                page, page_count(page));
633                 put_page(page);
634         }
635 }
636
637 /*
638  * release a reference to a region
639  * - the caller must hold the region semaphore for writing, which this releases
640  * - the region may not have been added to the tree yet, in which case vm_top
641  *   will equal vm_start
642  */
643 static void __put_nommu_region(struct vm_region *region)
644         __releases(nommu_region_sem)
645 {
646         kenter("%p{%d}", region, region->vm_usage);
647
648         BUG_ON(!nommu_region_tree.rb_node);
649
650         if (--region->vm_usage == 0) {
651                 if (region->vm_top > region->vm_start)
652                         delete_nommu_region(region);
653                 up_write(&nommu_region_sem);
654
655                 if (region->vm_file)
656                         fput(region->vm_file);
657
658                 /* IO memory and memory shared directly out of the pagecache
659                  * from ramfs/tmpfs mustn't be released here */
660                 if (region->vm_flags & VM_MAPPED_COPY) {
661                         kdebug("free series");
662                         free_page_series(region->vm_start, region->vm_top);
663                 }
664                 kmem_cache_free(vm_region_jar, region);
665         } else {
666                 up_write(&nommu_region_sem);
667         }
668 }
669
670 /*
671  * release a reference to a region
672  */
673 static void put_nommu_region(struct vm_region *region)
674 {
675         down_write(&nommu_region_sem);
676         __put_nommu_region(region);
677 }
678
679 /*
680  * update protection on a vma
681  */
682 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
683 {
684 #ifdef CONFIG_MPU
685         struct mm_struct *mm = vma->vm_mm;
686         long start = vma->vm_start & PAGE_MASK;
687         while (start < vma->vm_end) {
688                 protect_page(mm, start, flags);
689                 start += PAGE_SIZE;
690         }
691         update_protections(mm);
692 #endif
693 }
694
695 /*
696  * add a VMA into a process's mm_struct in the appropriate place in the list
697  * and tree and add to the address space's page tree also if not an anonymous
698  * page
699  * - should be called with mm->mmap_sem held writelocked
700  */
701 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
702 {
703         struct vm_area_struct *pvma, *prev;
704         struct address_space *mapping;
705         struct rb_node **p, *parent, *rb_prev;
706
707         kenter(",%p", vma);
708
709         BUG_ON(!vma->vm_region);
710
711         mm->map_count++;
712         vma->vm_mm = mm;
713
714         protect_vma(vma, vma->vm_flags);
715
716         /* add the VMA to the mapping */
717         if (vma->vm_file) {
718                 mapping = vma->vm_file->f_mapping;
719
720                 mutex_lock(&mapping->i_mmap_mutex);
721                 flush_dcache_mmap_lock(mapping);
722                 vma_interval_tree_insert(vma, &mapping->i_mmap);
723                 flush_dcache_mmap_unlock(mapping);
724                 mutex_unlock(&mapping->i_mmap_mutex);
725         }
726
727         /* add the VMA to the tree */
728         parent = rb_prev = NULL;
729         p = &mm->mm_rb.rb_node;
730         while (*p) {
731                 parent = *p;
732                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
733
734                 /* sort by: start addr, end addr, VMA struct addr in that order
735                  * (the latter is necessary as we may get identical VMAs) */
736                 if (vma->vm_start < pvma->vm_start)
737                         p = &(*p)->rb_left;
738                 else if (vma->vm_start > pvma->vm_start) {
739                         rb_prev = parent;
740                         p = &(*p)->rb_right;
741                 } else if (vma->vm_end < pvma->vm_end)
742                         p = &(*p)->rb_left;
743                 else if (vma->vm_end > pvma->vm_end) {
744                         rb_prev = parent;
745                         p = &(*p)->rb_right;
746                 } else if (vma < pvma)
747                         p = &(*p)->rb_left;
748                 else if (vma > pvma) {
749                         rb_prev = parent;
750                         p = &(*p)->rb_right;
751                 } else
752                         BUG();
753         }
754
755         rb_link_node(&vma->vm_rb, parent, p);
756         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
757
758         /* add VMA to the VMA list also */
759         prev = NULL;
760         if (rb_prev)
761                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
762
763         __vma_link_list(mm, vma, prev, parent);
764 }
765
766 /*
767  * delete a VMA from its owning mm_struct and address space
768  */
769 static void delete_vma_from_mm(struct vm_area_struct *vma)
770 {
771         struct address_space *mapping;
772         struct mm_struct *mm = vma->vm_mm;
773
774         kenter("%p", vma);
775
776         protect_vma(vma, 0);
777
778         mm->map_count--;
779         if (mm->mmap_cache == vma)
780                 mm->mmap_cache = NULL;
781
782         /* remove the VMA from the mapping */
783         if (vma->vm_file) {
784                 mapping = vma->vm_file->f_mapping;
785
786                 mutex_lock(&mapping->i_mmap_mutex);
787                 flush_dcache_mmap_lock(mapping);
788                 vma_interval_tree_remove(vma, &mapping->i_mmap);
789                 flush_dcache_mmap_unlock(mapping);
790                 mutex_unlock(&mapping->i_mmap_mutex);
791         }
792
793         /* remove from the MM's tree and list */
794         rb_erase(&vma->vm_rb, &mm->mm_rb);
795
796         if (vma->vm_prev)
797                 vma->vm_prev->vm_next = vma->vm_next;
798         else
799                 mm->mmap = vma->vm_next;
800
801         if (vma->vm_next)
802                 vma->vm_next->vm_prev = vma->vm_prev;
803 }
804
805 /*
806  * destroy a VMA record
807  */
808 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
809 {
810         kenter("%p", vma);
811         if (vma->vm_ops && vma->vm_ops->close)
812                 vma->vm_ops->close(vma);
813         if (vma->vm_file)
814                 fput(vma->vm_file);
815         put_nommu_region(vma->vm_region);
816         kmem_cache_free(vm_area_cachep, vma);
817 }
818
819 /*
820  * look up the first VMA in which addr resides, NULL if none
821  * - should be called with mm->mmap_sem at least held readlocked
822  */
823 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
824 {
825         struct vm_area_struct *vma;
826
827         /* check the cache first */
828         vma = ACCESS_ONCE(mm->mmap_cache);
829         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
830                 return vma;
831
832         /* trawl the list (there may be multiple mappings in which addr
833          * resides) */
834         for (vma = mm->mmap; vma; vma = vma->vm_next) {
835                 if (vma->vm_start > addr)
836                         return NULL;
837                 if (vma->vm_end > addr) {
838                         mm->mmap_cache = vma;
839                         return vma;
840                 }
841         }
842
843         return NULL;
844 }
845 EXPORT_SYMBOL(find_vma);
846
847 /*
848  * find a VMA
849  * - we don't extend stack VMAs under NOMMU conditions
850  */
851 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
852 {
853         return find_vma(mm, addr);
854 }
855
856 /*
857  * expand a stack to a given address
858  * - not supported under NOMMU conditions
859  */
860 int expand_stack(struct vm_area_struct *vma, unsigned long address)
861 {
862         return -ENOMEM;
863 }
864
865 /*
866  * look up the first VMA exactly that exactly matches addr
867  * - should be called with mm->mmap_sem at least held readlocked
868  */
869 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
870                                              unsigned long addr,
871                                              unsigned long len)
872 {
873         struct vm_area_struct *vma;
874         unsigned long end = addr + len;
875
876         /* check the cache first */
877         vma = mm->mmap_cache;
878         if (vma && vma->vm_start == addr && vma->vm_end == end)
879                 return vma;
880
881         /* trawl the list (there may be multiple mappings in which addr
882          * resides) */
883         for (vma = mm->mmap; vma; vma = vma->vm_next) {
884                 if (vma->vm_start < addr)
885                         continue;
886                 if (vma->vm_start > addr)
887                         return NULL;
888                 if (vma->vm_end == end) {
889                         mm->mmap_cache = vma;
890                         return vma;
891                 }
892         }
893
894         return NULL;
895 }
896
897 /*
898  * determine whether a mapping should be permitted and, if so, what sort of
899  * mapping we're capable of supporting
900  */
901 static int validate_mmap_request(struct file *file,
902                                  unsigned long addr,
903                                  unsigned long len,
904                                  unsigned long prot,
905                                  unsigned long flags,
906                                  unsigned long pgoff,
907                                  unsigned long *_capabilities)
908 {
909         unsigned long capabilities, rlen;
910         int ret;
911
912         /* do the simple checks first */
913         if (flags & MAP_FIXED) {
914                 printk(KERN_DEBUG
915                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
916                        current->pid);
917                 return -EINVAL;
918         }
919
920         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
921             (flags & MAP_TYPE) != MAP_SHARED)
922                 return -EINVAL;
923
924         if (!len)
925                 return -EINVAL;
926
927         /* Careful about overflows.. */
928         rlen = PAGE_ALIGN(len);
929         if (!rlen || rlen > TASK_SIZE)
930                 return -ENOMEM;
931
932         /* offset overflow? */
933         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
934                 return -EOVERFLOW;
935
936         if (file) {
937                 /* validate file mapping requests */
938                 struct address_space *mapping;
939
940                 /* files must support mmap */
941                 if (!file->f_op->mmap)
942                         return -ENODEV;
943
944                 /* work out if what we've got could possibly be shared
945                  * - we support chardevs that provide their own "memory"
946                  * - we support files/blockdevs that are memory backed
947                  */
948                 mapping = file->f_mapping;
949                 if (!mapping)
950                         mapping = file_inode(file)->i_mapping;
951
952                 capabilities = 0;
953                 if (mapping && mapping->backing_dev_info)
954                         capabilities = mapping->backing_dev_info->capabilities;
955
956                 if (!capabilities) {
957                         /* no explicit capabilities set, so assume some
958                          * defaults */
959                         switch (file_inode(file)->i_mode & S_IFMT) {
960                         case S_IFREG:
961                         case S_IFBLK:
962                                 capabilities = BDI_CAP_MAP_COPY;
963                                 break;
964
965                         case S_IFCHR:
966                                 capabilities =
967                                         BDI_CAP_MAP_DIRECT |
968                                         BDI_CAP_READ_MAP |
969                                         BDI_CAP_WRITE_MAP;
970                                 break;
971
972                         default:
973                                 return -EINVAL;
974                         }
975                 }
976
977                 /* eliminate any capabilities that we can't support on this
978                  * device */
979                 if (!file->f_op->get_unmapped_area)
980                         capabilities &= ~BDI_CAP_MAP_DIRECT;
981                 if (!file->f_op->read)
982                         capabilities &= ~BDI_CAP_MAP_COPY;
983
984                 /* The file shall have been opened with read permission. */
985                 if (!(file->f_mode & FMODE_READ))
986                         return -EACCES;
987
988                 if (flags & MAP_SHARED) {
989                         /* do checks for writing, appending and locking */
990                         if ((prot & PROT_WRITE) &&
991                             !(file->f_mode & FMODE_WRITE))
992                                 return -EACCES;
993
994                         if (IS_APPEND(file_inode(file)) &&
995                             (file->f_mode & FMODE_WRITE))
996                                 return -EACCES;
997
998                         if (locks_verify_locked(file_inode(file)))
999                                 return -EAGAIN;
1000
1001                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
1002                                 return -ENODEV;
1003
1004                         /* we mustn't privatise shared mappings */
1005                         capabilities &= ~BDI_CAP_MAP_COPY;
1006                 }
1007                 else {
1008                         /* we're going to read the file into private memory we
1009                          * allocate */
1010                         if (!(capabilities & BDI_CAP_MAP_COPY))
1011                                 return -ENODEV;
1012
1013                         /* we don't permit a private writable mapping to be
1014                          * shared with the backing device */
1015                         if (prot & PROT_WRITE)
1016                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1017                 }
1018
1019                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1020                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1021                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1022                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1023                             ) {
1024                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1025                                 if (flags & MAP_SHARED) {
1026                                         printk(KERN_WARNING
1027                                                "MAP_SHARED not completely supported on !MMU\n");
1028                                         return -EINVAL;
1029                                 }
1030                         }
1031                 }
1032
1033                 /* handle executable mappings and implied executable
1034                  * mappings */
1035                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1036                         if (prot & PROT_EXEC)
1037                                 return -EPERM;
1038                 }
1039                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1040                         /* handle implication of PROT_EXEC by PROT_READ */
1041                         if (current->personality & READ_IMPLIES_EXEC) {
1042                                 if (capabilities & BDI_CAP_EXEC_MAP)
1043                                         prot |= PROT_EXEC;
1044                         }
1045                 }
1046                 else if ((prot & PROT_READ) &&
1047                          (prot & PROT_EXEC) &&
1048                          !(capabilities & BDI_CAP_EXEC_MAP)
1049                          ) {
1050                         /* backing file is not executable, try to copy */
1051                         capabilities &= ~BDI_CAP_MAP_DIRECT;
1052                 }
1053         }
1054         else {
1055                 /* anonymous mappings are always memory backed and can be
1056                  * privately mapped
1057                  */
1058                 capabilities = BDI_CAP_MAP_COPY;
1059
1060                 /* handle PROT_EXEC implication by PROT_READ */
1061                 if ((prot & PROT_READ) &&
1062                     (current->personality & READ_IMPLIES_EXEC))
1063                         prot |= PROT_EXEC;
1064         }
1065
1066         /* allow the security API to have its say */
1067         ret = security_mmap_addr(addr);
1068         if (ret < 0)
1069                 return ret;
1070
1071         /* looks okay */
1072         *_capabilities = capabilities;
1073         return 0;
1074 }
1075
1076 /*
1077  * we've determined that we can make the mapping, now translate what we
1078  * now know into VMA flags
1079  */
1080 static unsigned long determine_vm_flags(struct file *file,
1081                                         unsigned long prot,
1082                                         unsigned long flags,
1083                                         unsigned long capabilities)
1084 {
1085         unsigned long vm_flags;
1086
1087         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1088         /* vm_flags |= mm->def_flags; */
1089
1090         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1091                 /* attempt to share read-only copies of mapped file chunks */
1092                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1093                 if (file && !(prot & PROT_WRITE))
1094                         vm_flags |= VM_MAYSHARE;
1095         } else {
1096                 /* overlay a shareable mapping on the backing device or inode
1097                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1098                  * romfs/cramfs */
1099                 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1100                 if (flags & MAP_SHARED)
1101                         vm_flags |= VM_SHARED;
1102         }
1103
1104         /* refuse to let anyone share private mappings with this process if
1105          * it's being traced - otherwise breakpoints set in it may interfere
1106          * with another untraced process
1107          */
1108         if ((flags & MAP_PRIVATE) && current->ptrace)
1109                 vm_flags &= ~VM_MAYSHARE;
1110
1111         return vm_flags;
1112 }
1113
1114 /*
1115  * set up a shared mapping on a file (the driver or filesystem provides and
1116  * pins the storage)
1117  */
1118 static int do_mmap_shared_file(struct vm_area_struct *vma)
1119 {
1120         int ret;
1121
1122         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1123         if (ret == 0) {
1124                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1125                 return 0;
1126         }
1127         if (ret != -ENOSYS)
1128                 return ret;
1129
1130         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1131          * opposed to tried but failed) so we can only give a suitable error as
1132          * it's not possible to make a private copy if MAP_SHARED was given */
1133         return -ENODEV;
1134 }
1135
1136 /*
1137  * set up a private mapping or an anonymous shared mapping
1138  */
1139 static int do_mmap_private(struct vm_area_struct *vma,
1140                            struct vm_region *region,
1141                            unsigned long len,
1142                            unsigned long capabilities)
1143 {
1144         struct page *pages;
1145         unsigned long total, point, n;
1146         void *base;
1147         int ret, order;
1148
1149         /* invoke the file's mapping function so that it can keep track of
1150          * shared mappings on devices or memory
1151          * - VM_MAYSHARE will be set if it may attempt to share
1152          */
1153         if (capabilities & BDI_CAP_MAP_DIRECT) {
1154                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1155                 if (ret == 0) {
1156                         /* shouldn't return success if we're not sharing */
1157                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1158                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1159                         return 0;
1160                 }
1161                 if (ret != -ENOSYS)
1162                         return ret;
1163
1164                 /* getting an ENOSYS error indicates that direct mmap isn't
1165                  * possible (as opposed to tried but failed) so we'll try to
1166                  * make a private copy of the data and map that instead */
1167         }
1168
1169
1170         /* allocate some memory to hold the mapping
1171          * - note that this may not return a page-aligned address if the object
1172          *   we're allocating is smaller than a page
1173          */
1174         order = get_order(len);
1175         kdebug("alloc order %d for %lx", order, len);
1176
1177         pages = alloc_pages(GFP_KERNEL, order);
1178         if (!pages)
1179                 goto enomem;
1180
1181         total = 1 << order;
1182         atomic_long_add(total, &mmap_pages_allocated);
1183
1184         point = len >> PAGE_SHIFT;
1185
1186         /* we allocated a power-of-2 sized page set, so we may want to trim off
1187          * the excess */
1188         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1189                 while (total > point) {
1190                         order = ilog2(total - point);
1191                         n = 1 << order;
1192                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1193                         atomic_long_sub(n, &mmap_pages_allocated);
1194                         total -= n;
1195                         set_page_refcounted(pages + total);
1196                         __free_pages(pages + total, order);
1197                 }
1198         }
1199
1200         for (point = 1; point < total; point++)
1201                 set_page_refcounted(&pages[point]);
1202
1203         base = page_address(pages);
1204         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1205         region->vm_start = (unsigned long) base;
1206         region->vm_end   = region->vm_start + len;
1207         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1208
1209         vma->vm_start = region->vm_start;
1210         vma->vm_end   = region->vm_start + len;
1211
1212         if (vma->vm_file) {
1213                 /* read the contents of a file into the copy */
1214                 mm_segment_t old_fs;
1215                 loff_t fpos;
1216
1217                 fpos = vma->vm_pgoff;
1218                 fpos <<= PAGE_SHIFT;
1219
1220                 old_fs = get_fs();
1221                 set_fs(KERNEL_DS);
1222                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1223                 set_fs(old_fs);
1224
1225                 if (ret < 0)
1226                         goto error_free;
1227
1228                 /* clear the last little bit */
1229                 if (ret < len)
1230                         memset(base + ret, 0, len - ret);
1231
1232         }
1233
1234         return 0;
1235
1236 error_free:
1237         free_page_series(region->vm_start, region->vm_top);
1238         region->vm_start = vma->vm_start = 0;
1239         region->vm_end   = vma->vm_end = 0;
1240         region->vm_top   = 0;
1241         return ret;
1242
1243 enomem:
1244         printk("Allocation of length %lu from process %d (%s) failed\n",
1245                len, current->pid, current->comm);
1246         show_free_areas(0);
1247         return -ENOMEM;
1248 }
1249
1250 /*
1251  * handle mapping creation for uClinux
1252  */
1253 unsigned long do_mmap_pgoff(struct file *file,
1254                             unsigned long addr,
1255                             unsigned long len,
1256                             unsigned long prot,
1257                             unsigned long flags,
1258                             unsigned long pgoff,
1259                             unsigned long *populate)
1260 {
1261         struct vm_area_struct *vma;
1262         struct vm_region *region;
1263         struct rb_node *rb;
1264         unsigned long capabilities, vm_flags, result;
1265         int ret;
1266
1267         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1268
1269         *populate = 0;
1270
1271         /* decide whether we should attempt the mapping, and if so what sort of
1272          * mapping */
1273         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1274                                     &capabilities);
1275         if (ret < 0) {
1276                 kleave(" = %d [val]", ret);
1277                 return ret;
1278         }
1279
1280         /* we ignore the address hint */
1281         addr = 0;
1282         len = PAGE_ALIGN(len);
1283
1284         /* we've determined that we can make the mapping, now translate what we
1285          * now know into VMA flags */
1286         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1287
1288         /* we're going to need to record the mapping */
1289         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1290         if (!region)
1291                 goto error_getting_region;
1292
1293         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1294         if (!vma)
1295                 goto error_getting_vma;
1296
1297         region->vm_usage = 1;
1298         region->vm_flags = vm_flags;
1299         region->vm_pgoff = pgoff;
1300
1301         INIT_LIST_HEAD(&vma->anon_vma_chain);
1302         vma->vm_flags = vm_flags;
1303         vma->vm_pgoff = pgoff;
1304
1305         if (file) {
1306                 region->vm_file = get_file(file);
1307                 vma->vm_file = get_file(file);
1308         }
1309
1310         down_write(&nommu_region_sem);
1311
1312         /* if we want to share, we need to check for regions created by other
1313          * mmap() calls that overlap with our proposed mapping
1314          * - we can only share with a superset match on most regular files
1315          * - shared mappings on character devices and memory backed files are
1316          *   permitted to overlap inexactly as far as we are concerned for in
1317          *   these cases, sharing is handled in the driver or filesystem rather
1318          *   than here
1319          */
1320         if (vm_flags & VM_MAYSHARE) {
1321                 struct vm_region *pregion;
1322                 unsigned long pglen, rpglen, pgend, rpgend, start;
1323
1324                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1325                 pgend = pgoff + pglen;
1326
1327                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1328                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1329
1330                         if (!(pregion->vm_flags & VM_MAYSHARE))
1331                                 continue;
1332
1333                         /* search for overlapping mappings on the same file */
1334                         if (file_inode(pregion->vm_file) !=
1335                             file_inode(file))
1336                                 continue;
1337
1338                         if (pregion->vm_pgoff >= pgend)
1339                                 continue;
1340
1341                         rpglen = pregion->vm_end - pregion->vm_start;
1342                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1343                         rpgend = pregion->vm_pgoff + rpglen;
1344                         if (pgoff >= rpgend)
1345                                 continue;
1346
1347                         /* handle inexactly overlapping matches between
1348                          * mappings */
1349                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1350                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1351                                 /* new mapping is not a subset of the region */
1352                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1353                                         goto sharing_violation;
1354                                 continue;
1355                         }
1356
1357                         /* we've found a region we can share */
1358                         pregion->vm_usage++;
1359                         vma->vm_region = pregion;
1360                         start = pregion->vm_start;
1361                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1362                         vma->vm_start = start;
1363                         vma->vm_end = start + len;
1364
1365                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1366                                 kdebug("share copy");
1367                                 vma->vm_flags |= VM_MAPPED_COPY;
1368                         } else {
1369                                 kdebug("share mmap");
1370                                 ret = do_mmap_shared_file(vma);
1371                                 if (ret < 0) {
1372                                         vma->vm_region = NULL;
1373                                         vma->vm_start = 0;
1374                                         vma->vm_end = 0;
1375                                         pregion->vm_usage--;
1376                                         pregion = NULL;
1377                                         goto error_just_free;
1378                                 }
1379                         }
1380                         fput(region->vm_file);
1381                         kmem_cache_free(vm_region_jar, region);
1382                         region = pregion;
1383                         result = start;
1384                         goto share;
1385                 }
1386
1387                 /* obtain the address at which to make a shared mapping
1388                  * - this is the hook for quasi-memory character devices to
1389                  *   tell us the location of a shared mapping
1390                  */
1391                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1392                         addr = file->f_op->get_unmapped_area(file, addr, len,
1393                                                              pgoff, flags);
1394                         if (IS_ERR_VALUE(addr)) {
1395                                 ret = addr;
1396                                 if (ret != -ENOSYS)
1397                                         goto error_just_free;
1398
1399                                 /* the driver refused to tell us where to site
1400                                  * the mapping so we'll have to attempt to copy
1401                                  * it */
1402                                 ret = -ENODEV;
1403                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1404                                         goto error_just_free;
1405
1406                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1407                         } else {
1408                                 vma->vm_start = region->vm_start = addr;
1409                                 vma->vm_end = region->vm_end = addr + len;
1410                         }
1411                 }
1412         }
1413
1414         vma->vm_region = region;
1415
1416         /* set up the mapping
1417          * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1418          */
1419         if (file && vma->vm_flags & VM_SHARED)
1420                 ret = do_mmap_shared_file(vma);
1421         else
1422                 ret = do_mmap_private(vma, region, len, capabilities);
1423         if (ret < 0)
1424                 goto error_just_free;
1425         add_nommu_region(region);
1426
1427         /* clear anonymous mappings that don't ask for uninitialized data */
1428         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1429                 memset((void *)region->vm_start, 0,
1430                        region->vm_end - region->vm_start);
1431
1432         /* okay... we have a mapping; now we have to register it */
1433         result = vma->vm_start;
1434
1435         current->mm->total_vm += len >> PAGE_SHIFT;
1436
1437 share:
1438         add_vma_to_mm(current->mm, vma);
1439
1440         /* we flush the region from the icache only when the first executable
1441          * mapping of it is made  */
1442         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1443                 flush_icache_range(region->vm_start, region->vm_end);
1444                 region->vm_icache_flushed = true;
1445         }
1446
1447         up_write(&nommu_region_sem);
1448
1449         kleave(" = %lx", result);
1450         return result;
1451
1452 error_just_free:
1453         up_write(&nommu_region_sem);
1454 error:
1455         if (region->vm_file)
1456                 fput(region->vm_file);
1457         kmem_cache_free(vm_region_jar, region);
1458         if (vma->vm_file)
1459                 fput(vma->vm_file);
1460         kmem_cache_free(vm_area_cachep, vma);
1461         kleave(" = %d", ret);
1462         return ret;
1463
1464 sharing_violation:
1465         up_write(&nommu_region_sem);
1466         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1467         ret = -EINVAL;
1468         goto error;
1469
1470 error_getting_vma:
1471         kmem_cache_free(vm_region_jar, region);
1472         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1473                " from process %d failed\n",
1474                len, current->pid);
1475         show_free_areas(0);
1476         return -ENOMEM;
1477
1478 error_getting_region:
1479         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1480                " from process %d failed\n",
1481                len, current->pid);
1482         show_free_areas(0);
1483         return -ENOMEM;
1484 }
1485
1486 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1487                 unsigned long, prot, unsigned long, flags,
1488                 unsigned long, fd, unsigned long, pgoff)
1489 {
1490         struct file *file = NULL;
1491         unsigned long retval = -EBADF;
1492
1493         audit_mmap_fd(fd, flags);
1494         if (!(flags & MAP_ANONYMOUS)) {
1495                 file = fget(fd);
1496                 if (!file)
1497                         goto out;
1498         }
1499
1500         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1501
1502         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1503
1504         if (file)
1505                 fput(file);
1506 out:
1507         return retval;
1508 }
1509
1510 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1511 struct mmap_arg_struct {
1512         unsigned long addr;
1513         unsigned long len;
1514         unsigned long prot;
1515         unsigned long flags;
1516         unsigned long fd;
1517         unsigned long offset;
1518 };
1519
1520 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1521 {
1522         struct mmap_arg_struct a;
1523
1524         if (copy_from_user(&a, arg, sizeof(a)))
1525                 return -EFAULT;
1526         if (a.offset & ~PAGE_MASK)
1527                 return -EINVAL;
1528
1529         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1530                               a.offset >> PAGE_SHIFT);
1531 }
1532 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1533
1534 /*
1535  * split a vma into two pieces at address 'addr', a new vma is allocated either
1536  * for the first part or the tail.
1537  */
1538 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1539               unsigned long addr, int new_below)
1540 {
1541         struct vm_area_struct *new;
1542         struct vm_region *region;
1543         unsigned long npages;
1544
1545         kenter("");
1546
1547         /* we're only permitted to split anonymous regions (these should have
1548          * only a single usage on the region) */
1549         if (vma->vm_file)
1550                 return -ENOMEM;
1551
1552         if (mm->map_count >= sysctl_max_map_count)
1553                 return -ENOMEM;
1554
1555         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1556         if (!region)
1557                 return -ENOMEM;
1558
1559         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1560         if (!new) {
1561                 kmem_cache_free(vm_region_jar, region);
1562                 return -ENOMEM;
1563         }
1564
1565         /* most fields are the same, copy all, and then fixup */
1566         *new = *vma;
1567         *region = *vma->vm_region;
1568         new->vm_region = region;
1569
1570         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1571
1572         if (new_below) {
1573                 region->vm_top = region->vm_end = new->vm_end = addr;
1574         } else {
1575                 region->vm_start = new->vm_start = addr;
1576                 region->vm_pgoff = new->vm_pgoff += npages;
1577         }
1578
1579         if (new->vm_ops && new->vm_ops->open)
1580                 new->vm_ops->open(new);
1581
1582         delete_vma_from_mm(vma);
1583         down_write(&nommu_region_sem);
1584         delete_nommu_region(vma->vm_region);
1585         if (new_below) {
1586                 vma->vm_region->vm_start = vma->vm_start = addr;
1587                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1588         } else {
1589                 vma->vm_region->vm_end = vma->vm_end = addr;
1590                 vma->vm_region->vm_top = addr;
1591         }
1592         add_nommu_region(vma->vm_region);
1593         add_nommu_region(new->vm_region);
1594         up_write(&nommu_region_sem);
1595         add_vma_to_mm(mm, vma);
1596         add_vma_to_mm(mm, new);
1597         return 0;
1598 }
1599
1600 /*
1601  * shrink a VMA by removing the specified chunk from either the beginning or
1602  * the end
1603  */
1604 static int shrink_vma(struct mm_struct *mm,
1605                       struct vm_area_struct *vma,
1606                       unsigned long from, unsigned long to)
1607 {
1608         struct vm_region *region;
1609
1610         kenter("");
1611
1612         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1613          * and list */
1614         delete_vma_from_mm(vma);
1615         if (from > vma->vm_start)
1616                 vma->vm_end = from;
1617         else
1618                 vma->vm_start = to;
1619         add_vma_to_mm(mm, vma);
1620
1621         /* cut the backing region down to size */
1622         region = vma->vm_region;
1623         BUG_ON(region->vm_usage != 1);
1624
1625         down_write(&nommu_region_sem);
1626         delete_nommu_region(region);
1627         if (from > region->vm_start) {
1628                 to = region->vm_top;
1629                 region->vm_top = region->vm_end = from;
1630         } else {
1631                 region->vm_start = to;
1632         }
1633         add_nommu_region(region);
1634         up_write(&nommu_region_sem);
1635
1636         free_page_series(from, to);
1637         return 0;
1638 }
1639
1640 /*
1641  * release a mapping
1642  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1643  *   VMA, though it need not cover the whole VMA
1644  */
1645 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1646 {
1647         struct vm_area_struct *vma;
1648         unsigned long end;
1649         int ret;
1650
1651         kenter(",%lx,%zx", start, len);
1652
1653         len = PAGE_ALIGN(len);
1654         if (len == 0)
1655                 return -EINVAL;
1656
1657         end = start + len;
1658
1659         /* find the first potentially overlapping VMA */
1660         vma = find_vma(mm, start);
1661         if (!vma) {
1662                 static int limit = 0;
1663                 if (limit < 5) {
1664                         printk(KERN_WARNING
1665                                "munmap of memory not mmapped by process %d"
1666                                " (%s): 0x%lx-0x%lx\n",
1667                                current->pid, current->comm,
1668                                start, start + len - 1);
1669                         limit++;
1670                 }
1671                 return -EINVAL;
1672         }
1673
1674         /* we're allowed to split an anonymous VMA but not a file-backed one */
1675         if (vma->vm_file) {
1676                 do {
1677                         if (start > vma->vm_start) {
1678                                 kleave(" = -EINVAL [miss]");
1679                                 return -EINVAL;
1680                         }
1681                         if (end == vma->vm_end)
1682                                 goto erase_whole_vma;
1683                         vma = vma->vm_next;
1684                 } while (vma);
1685                 kleave(" = -EINVAL [split file]");
1686                 return -EINVAL;
1687         } else {
1688                 /* the chunk must be a subset of the VMA found */
1689                 if (start == vma->vm_start && end == vma->vm_end)
1690                         goto erase_whole_vma;
1691                 if (start < vma->vm_start || end > vma->vm_end) {
1692                         kleave(" = -EINVAL [superset]");
1693                         return -EINVAL;
1694                 }
1695                 if (start & ~PAGE_MASK) {
1696                         kleave(" = -EINVAL [unaligned start]");
1697                         return -EINVAL;
1698                 }
1699                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1700                         kleave(" = -EINVAL [unaligned split]");
1701                         return -EINVAL;
1702                 }
1703                 if (start != vma->vm_start && end != vma->vm_end) {
1704                         ret = split_vma(mm, vma, start, 1);
1705                         if (ret < 0) {
1706                                 kleave(" = %d [split]", ret);
1707                                 return ret;
1708                         }
1709                 }
1710                 return shrink_vma(mm, vma, start, end);
1711         }
1712
1713 erase_whole_vma:
1714         delete_vma_from_mm(vma);
1715         delete_vma(mm, vma);
1716         kleave(" = 0");
1717         return 0;
1718 }
1719 EXPORT_SYMBOL(do_munmap);
1720
1721 int vm_munmap(unsigned long addr, size_t len)
1722 {
1723         struct mm_struct *mm = current->mm;
1724         int ret;
1725
1726         down_write(&mm->mmap_sem);
1727         ret = do_munmap(mm, addr, len);
1728         up_write(&mm->mmap_sem);
1729         return ret;
1730 }
1731 EXPORT_SYMBOL(vm_munmap);
1732
1733 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1734 {
1735         return vm_munmap(addr, len);
1736 }
1737
1738 /*
1739  * release all the mappings made in a process's VM space
1740  */
1741 void exit_mmap(struct mm_struct *mm)
1742 {
1743         struct vm_area_struct *vma;
1744
1745         if (!mm)
1746                 return;
1747
1748         kenter("");
1749
1750         mm->total_vm = 0;
1751
1752         while ((vma = mm->mmap)) {
1753                 mm->mmap = vma->vm_next;
1754                 delete_vma_from_mm(vma);
1755                 delete_vma(mm, vma);
1756                 cond_resched();
1757         }
1758
1759         kleave("");
1760 }
1761
1762 unsigned long vm_brk(unsigned long addr, unsigned long len)
1763 {
1764         return -ENOMEM;
1765 }
1766
1767 /*
1768  * expand (or shrink) an existing mapping, potentially moving it at the same
1769  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1770  *
1771  * under NOMMU conditions, we only permit changing a mapping's size, and only
1772  * as long as it stays within the region allocated by do_mmap_private() and the
1773  * block is not shareable
1774  *
1775  * MREMAP_FIXED is not supported under NOMMU conditions
1776  */
1777 static unsigned long do_mremap(unsigned long addr,
1778                         unsigned long old_len, unsigned long new_len,
1779                         unsigned long flags, unsigned long new_addr)
1780 {
1781         struct vm_area_struct *vma;
1782
1783         /* insanity checks first */
1784         old_len = PAGE_ALIGN(old_len);
1785         new_len = PAGE_ALIGN(new_len);
1786         if (old_len == 0 || new_len == 0)
1787                 return (unsigned long) -EINVAL;
1788
1789         if (addr & ~PAGE_MASK)
1790                 return -EINVAL;
1791
1792         if (flags & MREMAP_FIXED && new_addr != addr)
1793                 return (unsigned long) -EINVAL;
1794
1795         vma = find_vma_exact(current->mm, addr, old_len);
1796         if (!vma)
1797                 return (unsigned long) -EINVAL;
1798
1799         if (vma->vm_end != vma->vm_start + old_len)
1800                 return (unsigned long) -EFAULT;
1801
1802         if (vma->vm_flags & VM_MAYSHARE)
1803                 return (unsigned long) -EPERM;
1804
1805         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1806                 return (unsigned long) -ENOMEM;
1807
1808         /* all checks complete - do it */
1809         vma->vm_end = vma->vm_start + new_len;
1810         return vma->vm_start;
1811 }
1812
1813 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1814                 unsigned long, new_len, unsigned long, flags,
1815                 unsigned long, new_addr)
1816 {
1817         unsigned long ret;
1818
1819         down_write(&current->mm->mmap_sem);
1820         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1821         up_write(&current->mm->mmap_sem);
1822         return ret;
1823 }
1824
1825 struct page *follow_page_mask(struct vm_area_struct *vma,
1826                               unsigned long address, unsigned int flags,
1827                               unsigned int *page_mask)
1828 {
1829         *page_mask = 0;
1830         return NULL;
1831 }
1832
1833 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1834                 unsigned long pfn, unsigned long size, pgprot_t prot)
1835 {
1836         if (addr != (pfn << PAGE_SHIFT))
1837                 return -EINVAL;
1838
1839         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1840         return 0;
1841 }
1842 EXPORT_SYMBOL(remap_pfn_range);
1843
1844 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1845 {
1846         unsigned long pfn = start >> PAGE_SHIFT;
1847         unsigned long vm_len = vma->vm_end - vma->vm_start;
1848
1849         pfn += vma->vm_pgoff;
1850         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1851 }
1852 EXPORT_SYMBOL(vm_iomap_memory);
1853
1854 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1855                         unsigned long pgoff)
1856 {
1857         unsigned int size = vma->vm_end - vma->vm_start;
1858
1859         if (!(vma->vm_flags & VM_USERMAP))
1860                 return -EINVAL;
1861
1862         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1863         vma->vm_end = vma->vm_start + size;
1864
1865         return 0;
1866 }
1867 EXPORT_SYMBOL(remap_vmalloc_range);
1868
1869 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1870         unsigned long len, unsigned long pgoff, unsigned long flags)
1871 {
1872         return -ENOMEM;
1873 }
1874
1875 void unmap_mapping_range(struct address_space *mapping,
1876                          loff_t const holebegin, loff_t const holelen,
1877                          int even_cows)
1878 {
1879 }
1880 EXPORT_SYMBOL(unmap_mapping_range);
1881
1882 /*
1883  * Check that a process has enough memory to allocate a new virtual
1884  * mapping. 0 means there is enough memory for the allocation to
1885  * succeed and -ENOMEM implies there is not.
1886  *
1887  * We currently support three overcommit policies, which are set via the
1888  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1889  *
1890  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1891  * Additional code 2002 Jul 20 by Robert Love.
1892  *
1893  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1894  *
1895  * Note this is a helper function intended to be used by LSMs which
1896  * wish to use this logic.
1897  */
1898 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1899 {
1900         unsigned long free, allowed, reserve;
1901
1902         vm_acct_memory(pages);
1903
1904         /*
1905          * Sometimes we want to use more memory than we have
1906          */
1907         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1908                 return 0;
1909
1910         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1911                 free = global_page_state(NR_FREE_PAGES);
1912                 free += global_page_state(NR_FILE_PAGES);
1913
1914                 /*
1915                  * shmem pages shouldn't be counted as free in this
1916                  * case, they can't be purged, only swapped out, and
1917                  * that won't affect the overall amount of available
1918                  * memory in the system.
1919                  */
1920                 free -= global_page_state(NR_SHMEM);
1921
1922                 free += get_nr_swap_pages();
1923
1924                 /*
1925                  * Any slabs which are created with the
1926                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1927                  * which are reclaimable, under pressure.  The dentry
1928                  * cache and most inode caches should fall into this
1929                  */
1930                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1931
1932                 /*
1933                  * Leave reserved pages. The pages are not for anonymous pages.
1934                  */
1935                 if (free <= totalreserve_pages)
1936                         goto error;
1937                 else
1938                         free -= totalreserve_pages;
1939
1940                 /*
1941                  * Reserve some for root
1942                  */
1943                 if (!cap_sys_admin)
1944                         free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1945
1946                 if (free > pages)
1947                         return 0;
1948
1949                 goto error;
1950         }
1951
1952         allowed = vm_commit_limit();
1953         /*
1954          * Reserve some 3% for root
1955          */
1956         if (!cap_sys_admin)
1957                 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1958
1959         /*
1960          * Don't let a single process grow so big a user can't recover
1961          */
1962         if (mm) {
1963                 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
1964                 allowed -= min(mm->total_vm / 32, reserve);
1965         }
1966
1967         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1968                 return 0;
1969
1970 error:
1971         vm_unacct_memory(pages);
1972
1973         return -ENOMEM;
1974 }
1975
1976 int in_gate_area_no_mm(unsigned long addr)
1977 {
1978         return 0;
1979 }
1980
1981 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1982 {
1983         BUG();
1984         return 0;
1985 }
1986 EXPORT_SYMBOL(filemap_fault);
1987
1988 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
1989                              unsigned long size, pgoff_t pgoff)
1990 {
1991         BUG();
1992         return 0;
1993 }
1994 EXPORT_SYMBOL(generic_file_remap_pages);
1995
1996 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1997                 unsigned long addr, void *buf, int len, int write)
1998 {
1999         struct vm_area_struct *vma;
2000
2001         down_read(&mm->mmap_sem);
2002
2003         /* the access must start within one of the target process's mappings */
2004         vma = find_vma(mm, addr);
2005         if (vma) {
2006                 /* don't overrun this mapping */
2007                 if (addr + len >= vma->vm_end)
2008                         len = vma->vm_end - addr;
2009
2010                 /* only read or write mappings where it is permitted */
2011                 if (write && vma->vm_flags & VM_MAYWRITE)
2012                         copy_to_user_page(vma, NULL, addr,
2013                                          (void *) addr, buf, len);
2014                 else if (!write && vma->vm_flags & VM_MAYREAD)
2015                         copy_from_user_page(vma, NULL, addr,
2016                                             buf, (void *) addr, len);
2017                 else
2018                         len = 0;
2019         } else {
2020                 len = 0;
2021         }
2022
2023         up_read(&mm->mmap_sem);
2024
2025         return len;
2026 }
2027
2028 /**
2029  * @access_remote_vm - access another process' address space
2030  * @mm:         the mm_struct of the target address space
2031  * @addr:       start address to access
2032  * @buf:        source or destination buffer
2033  * @len:        number of bytes to transfer
2034  * @write:      whether the access is a write
2035  *
2036  * The caller must hold a reference on @mm.
2037  */
2038 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2039                 void *buf, int len, int write)
2040 {
2041         return __access_remote_vm(NULL, mm, addr, buf, len, write);
2042 }
2043
2044 /*
2045  * Access another process' address space.
2046  * - source/target buffer must be kernel space
2047  */
2048 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2049 {
2050         struct mm_struct *mm;
2051
2052         if (addr + len < addr)
2053                 return 0;
2054
2055         mm = get_task_mm(tsk);
2056         if (!mm)
2057                 return 0;
2058
2059         len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2060
2061         mmput(mm);
2062         return len;
2063 }
2064
2065 /**
2066  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2067  * @inode: The inode to check
2068  * @size: The current filesize of the inode
2069  * @newsize: The proposed filesize of the inode
2070  *
2071  * Check the shared mappings on an inode on behalf of a shrinking truncate to
2072  * make sure that that any outstanding VMAs aren't broken and then shrink the
2073  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2074  * automatically grant mappings that are too large.
2075  */
2076 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2077                                 size_t newsize)
2078 {
2079         struct vm_area_struct *vma;
2080         struct vm_region *region;
2081         pgoff_t low, high;
2082         size_t r_size, r_top;
2083
2084         low = newsize >> PAGE_SHIFT;
2085         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2086
2087         down_write(&nommu_region_sem);
2088         mutex_lock(&inode->i_mapping->i_mmap_mutex);
2089
2090         /* search for VMAs that fall within the dead zone */
2091         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
2092                 /* found one - only interested if it's shared out of the page
2093                  * cache */
2094                 if (vma->vm_flags & VM_SHARED) {
2095                         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2096                         up_write(&nommu_region_sem);
2097                         return -ETXTBSY; /* not quite true, but near enough */
2098                 }
2099         }
2100
2101         /* reduce any regions that overlap the dead zone - if in existence,
2102          * these will be pointed to by VMAs that don't overlap the dead zone
2103          *
2104          * we don't check for any regions that start beyond the EOF as there
2105          * shouldn't be any
2106          */
2107         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
2108                                   0, ULONG_MAX) {
2109                 if (!(vma->vm_flags & VM_SHARED))
2110                         continue;
2111
2112                 region = vma->vm_region;
2113                 r_size = region->vm_top - region->vm_start;
2114                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2115
2116                 if (r_top > newsize) {
2117                         region->vm_top -= r_top - newsize;
2118                         if (region->vm_end > region->vm_top)
2119                                 region->vm_end = region->vm_top;
2120                 }
2121         }
2122
2123         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2124         up_write(&nommu_region_sem);
2125         return 0;
2126 }
2127
2128 /*
2129  * Initialise sysctl_user_reserve_kbytes.
2130  *
2131  * This is intended to prevent a user from starting a single memory hogging
2132  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
2133  * mode.
2134  *
2135  * The default value is min(3% of free memory, 128MB)
2136  * 128MB is enough to recover with sshd/login, bash, and top/kill.
2137  */
2138 static int __meminit init_user_reserve(void)
2139 {
2140         unsigned long free_kbytes;
2141
2142         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2143
2144         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
2145         return 0;
2146 }
2147 module_init(init_user_reserve)
2148
2149 /*
2150  * Initialise sysctl_admin_reserve_kbytes.
2151  *
2152  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
2153  * to log in and kill a memory hogging process.
2154  *
2155  * Systems with more than 256MB will reserve 8MB, enough to recover
2156  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
2157  * only reserve 3% of free pages by default.
2158  */
2159 static int __meminit init_admin_reserve(void)
2160 {
2161         unsigned long free_kbytes;
2162
2163         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2164
2165         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
2166         return 0;
2167 }
2168 module_init(init_admin_reserve)