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Linux/mm/nommu.c

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  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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 17 
 18 #include <linux/export.h>
 19 #include <linux/mm.h>
 20 #include <linux/sched/mm.h>
 21 #include <linux/vmacache.h>
 22 #include <linux/mman.h>
 23 #include <linux/swap.h>
 24 #include <linux/file.h>
 25 #include <linux/highmem.h>
 26 #include <linux/pagemap.h>
 27 #include <linux/slab.h>
 28 #include <linux/vmalloc.h>
 29 #include <linux/blkdev.h>
 30 #include <linux/backing-dev.h>
 31 #include <linux/compiler.h>
 32 #include <linux/mount.h>
 33 #include <linux/personality.h>
 34 #include <linux/security.h>
 35 #include <linux/syscalls.h>
 36 #include <linux/audit.h>
 37 #include <linux/printk.h>
 38 
 39 #include <linux/uaccess.h>
 40 #include <asm/tlb.h>
 41 #include <asm/tlbflush.h>
 42 #include <asm/mmu_context.h>
 43 #include "internal.h"
 44 
 45 void *high_memory;
 46 EXPORT_SYMBOL(high_memory);
 47 struct page *mem_map;
 48 unsigned long max_mapnr;
 49 EXPORT_SYMBOL(max_mapnr);
 50 unsigned long highest_memmap_pfn;
 51 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
 52 int heap_stack_gap = 0;
 53 
 54 atomic_long_t mmap_pages_allocated;
 55 
 56 EXPORT_SYMBOL(mem_map);
 57 
 58 /* list of mapped, potentially shareable regions */
 59 static struct kmem_cache *vm_region_jar;
 60 struct rb_root nommu_region_tree = RB_ROOT;
 61 DECLARE_RWSEM(nommu_region_sem);
 62 
 63 const struct vm_operations_struct generic_file_vm_ops = {
 64 };
 65 
 66 /*
 67  * Return the total memory allocated for this pointer, not
 68  * just what the caller asked for.
 69  *
 70  * Doesn't have to be accurate, i.e. may have races.
 71  */
 72 unsigned int kobjsize(const void *objp)
 73 {
 74         struct page *page;
 75 
 76         /*
 77          * If the object we have should not have ksize performed on it,
 78          * return size of 0
 79          */
 80         if (!objp || !virt_addr_valid(objp))
 81                 return 0;
 82 
 83         page = virt_to_head_page(objp);
 84 
 85         /*
 86          * If the allocator sets PageSlab, we know the pointer came from
 87          * kmalloc().
 88          */
 89         if (PageSlab(page))
 90                 return ksize(objp);
 91 
 92         /*
 93          * If it's not a compound page, see if we have a matching VMA
 94          * region. This test is intentionally done in reverse order,
 95          * so if there's no VMA, we still fall through and hand back
 96          * PAGE_SIZE for 0-order pages.
 97          */
 98         if (!PageCompound(page)) {
 99                 struct vm_area_struct *vma;
100 
101                 vma = find_vma(current->mm, (unsigned long)objp);
102                 if (vma)
103                         return vma->vm_end - vma->vm_start;
104         }
105 
106         /*
107          * The ksize() function is only guaranteed to work for pointers
108          * returned by kmalloc(). So handle arbitrary pointers here.
109          */
110         return PAGE_SIZE << compound_order(page);
111 }
112 
113 static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
114                       unsigned long start, unsigned long nr_pages,
115                       unsigned int foll_flags, struct page **pages,
116                       struct vm_area_struct **vmas, int *nonblocking)
117 {
118         struct vm_area_struct *vma;
119         unsigned long vm_flags;
120         int i;
121 
122         /* calculate required read or write permissions.
123          * If FOLL_FORCE is set, we only require the "MAY" flags.
124          */
125         vm_flags  = (foll_flags & FOLL_WRITE) ?
126                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
127         vm_flags &= (foll_flags & FOLL_FORCE) ?
128                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
129 
130         for (i = 0; i < nr_pages; i++) {
131                 vma = find_vma(mm, start);
132                 if (!vma)
133                         goto finish_or_fault;
134 
135                 /* protect what we can, including chardevs */
136                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
137                     !(vm_flags & vma->vm_flags))
138                         goto finish_or_fault;
139 
140                 if (pages) {
141                         pages[i] = virt_to_page(start);
142                         if (pages[i])
143                                 get_page(pages[i]);
144                 }
145                 if (vmas)
146                         vmas[i] = vma;
147                 start = (start + PAGE_SIZE) & PAGE_MASK;
148         }
149 
150         return i;
151 
152 finish_or_fault:
153         return i ? : -EFAULT;
154 }
155 
156 /*
157  * get a list of pages in an address range belonging to the specified process
158  * and indicate the VMA that covers each page
159  * - this is potentially dodgy as we may end incrementing the page count of a
160  *   slab page or a secondary page from a compound page
161  * - don't permit access to VMAs that don't support it, such as I/O mappings
162  */
163 long get_user_pages(unsigned long start, unsigned long nr_pages,
164                     unsigned int gup_flags, struct page **pages,
165                     struct vm_area_struct **vmas)
166 {
167         return __get_user_pages(current, current->mm, start, nr_pages,
168                                 gup_flags, pages, vmas, NULL);
169 }
170 EXPORT_SYMBOL(get_user_pages);
171 
172 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
173                             unsigned int gup_flags, struct page **pages,
174                             int *locked)
175 {
176         return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
177 }
178 EXPORT_SYMBOL(get_user_pages_locked);
179 
180 static long __get_user_pages_unlocked(struct task_struct *tsk,
181                         struct mm_struct *mm, unsigned long start,
182                         unsigned long nr_pages, struct page **pages,
183                         unsigned int gup_flags)
184 {
185         long ret;
186         down_read(&mm->mmap_sem);
187         ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
188                                 NULL, NULL);
189         up_read(&mm->mmap_sem);
190         return ret;
191 }
192 
193 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
194                              struct page **pages, unsigned int gup_flags)
195 {
196         return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
197                                          pages, gup_flags);
198 }
199 EXPORT_SYMBOL(get_user_pages_unlocked);
200 
201 /**
202  * follow_pfn - look up PFN at a user virtual address
203  * @vma: memory mapping
204  * @address: user virtual address
205  * @pfn: location to store found PFN
206  *
207  * Only IO mappings and raw PFN mappings are allowed.
208  *
209  * Returns zero and the pfn at @pfn on success, -ve otherwise.
210  */
211 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
212         unsigned long *pfn)
213 {
214         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
215                 return -EINVAL;
216 
217         *pfn = address >> PAGE_SHIFT;
218         return 0;
219 }
220 EXPORT_SYMBOL(follow_pfn);
221 
222 LIST_HEAD(vmap_area_list);
223 
224 void vfree(const void *addr)
225 {
226         kfree(addr);
227 }
228 EXPORT_SYMBOL(vfree);
229 
230 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
231 {
232         /*
233          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
234          * returns only a logical address.
235          */
236         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
237 }
238 EXPORT_SYMBOL(__vmalloc);
239 
240 void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags)
241 {
242         return __vmalloc(size, flags, PAGE_KERNEL);
243 }
244 
245 void *vmalloc_user(unsigned long size)
246 {
247         void *ret;
248 
249         ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
250         if (ret) {
251                 struct vm_area_struct *vma;
252 
253                 down_write(&current->mm->mmap_sem);
254                 vma = find_vma(current->mm, (unsigned long)ret);
255                 if (vma)
256                         vma->vm_flags |= VM_USERMAP;
257                 up_write(&current->mm->mmap_sem);
258         }
259 
260         return ret;
261 }
262 EXPORT_SYMBOL(vmalloc_user);
263 
264 struct page *vmalloc_to_page(const void *addr)
265 {
266         return virt_to_page(addr);
267 }
268 EXPORT_SYMBOL(vmalloc_to_page);
269 
270 unsigned long vmalloc_to_pfn(const void *addr)
271 {
272         return page_to_pfn(virt_to_page(addr));
273 }
274 EXPORT_SYMBOL(vmalloc_to_pfn);
275 
276 long vread(char *buf, char *addr, unsigned long count)
277 {
278         /* Don't allow overflow */
279         if ((unsigned long) buf + count < count)
280                 count = -(unsigned long) buf;
281 
282         memcpy(buf, addr, count);
283         return count;
284 }
285 
286 long vwrite(char *buf, char *addr, unsigned long count)
287 {
288         /* Don't allow overflow */
289         if ((unsigned long) addr + count < count)
290                 count = -(unsigned long) addr;
291 
292         memcpy(addr, buf, count);
293         return count;
294 }
295 
296 /*
297  *      vmalloc  -  allocate virtually contiguous memory
298  *
299  *      @size:          allocation size
300  *
301  *      Allocate enough pages to cover @size from the page level
302  *      allocator and map them into contiguous kernel virtual space.
303  *
304  *      For tight control over page level allocator and protection flags
305  *      use __vmalloc() instead.
306  */
307 void *vmalloc(unsigned long size)
308 {
309        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
310 }
311 EXPORT_SYMBOL(vmalloc);
312 
313 /*
314  *      vzalloc - allocate virtually contiguous memory with zero fill
315  *
316  *      @size:          allocation size
317  *
318  *      Allocate enough pages to cover @size from the page level
319  *      allocator and map them into contiguous kernel virtual space.
320  *      The memory allocated is set to zero.
321  *
322  *      For tight control over page level allocator and protection flags
323  *      use __vmalloc() instead.
324  */
325 void *vzalloc(unsigned long size)
326 {
327         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
328                         PAGE_KERNEL);
329 }
330 EXPORT_SYMBOL(vzalloc);
331 
332 /**
333  * vmalloc_node - allocate memory on a specific node
334  * @size:       allocation size
335  * @node:       numa node
336  *
337  * Allocate enough pages to cover @size from the page level
338  * allocator and map them into contiguous kernel virtual space.
339  *
340  * For tight control over page level allocator and protection flags
341  * use __vmalloc() instead.
342  */
343 void *vmalloc_node(unsigned long size, int node)
344 {
345         return vmalloc(size);
346 }
347 EXPORT_SYMBOL(vmalloc_node);
348 
349 /**
350  * vzalloc_node - allocate memory on a specific node with zero fill
351  * @size:       allocation size
352  * @node:       numa node
353  *
354  * Allocate enough pages to cover @size from the page level
355  * allocator and map them into contiguous kernel virtual space.
356  * The memory allocated is set to zero.
357  *
358  * For tight control over page level allocator and protection flags
359  * use __vmalloc() instead.
360  */
361 void *vzalloc_node(unsigned long size, int node)
362 {
363         return vzalloc(size);
364 }
365 EXPORT_SYMBOL(vzalloc_node);
366 
367 #ifndef PAGE_KERNEL_EXEC
368 # define PAGE_KERNEL_EXEC PAGE_KERNEL
369 #endif
370 
371 /**
372  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
373  *      @size:          allocation size
374  *
375  *      Kernel-internal function to allocate enough pages to cover @size
376  *      the page level allocator and map them into contiguous and
377  *      executable kernel virtual space.
378  *
379  *      For tight control over page level allocator and protection flags
380  *      use __vmalloc() instead.
381  */
382 
383 void *vmalloc_exec(unsigned long size)
384 {
385         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
386 }
387 
388 /**
389  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
390  *      @size:          allocation size
391  *
392  *      Allocate enough 32bit PA addressable pages to cover @size from the
393  *      page level allocator and map them into contiguous kernel virtual space.
394  */
395 void *vmalloc_32(unsigned long size)
396 {
397         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
398 }
399 EXPORT_SYMBOL(vmalloc_32);
400 
401 /**
402  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
403  *      @size:          allocation size
404  *
405  * The resulting memory area is 32bit addressable and zeroed so it can be
406  * mapped to userspace without leaking data.
407  *
408  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
409  * remap_vmalloc_range() are permissible.
410  */
411 void *vmalloc_32_user(unsigned long size)
412 {
413         /*
414          * We'll have to sort out the ZONE_DMA bits for 64-bit,
415          * but for now this can simply use vmalloc_user() directly.
416          */
417         return vmalloc_user(size);
418 }
419 EXPORT_SYMBOL(vmalloc_32_user);
420 
421 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
422 {
423         BUG();
424         return NULL;
425 }
426 EXPORT_SYMBOL(vmap);
427 
428 void vunmap(const void *addr)
429 {
430         BUG();
431 }
432 EXPORT_SYMBOL(vunmap);
433 
434 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
435 {
436         BUG();
437         return NULL;
438 }
439 EXPORT_SYMBOL(vm_map_ram);
440 
441 void vm_unmap_ram(const void *mem, unsigned int count)
442 {
443         BUG();
444 }
445 EXPORT_SYMBOL(vm_unmap_ram);
446 
447 void vm_unmap_aliases(void)
448 {
449 }
450 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
451 
452 /*
453  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
454  * have one.
455  */
456 void __weak vmalloc_sync_all(void)
457 {
458 }
459 
460 /**
461  *      alloc_vm_area - allocate a range of kernel address space
462  *      @size:          size of the area
463  *
464  *      Returns:        NULL on failure, vm_struct on success
465  *
466  *      This function reserves a range of kernel address space, and
467  *      allocates pagetables to map that range.  No actual mappings
468  *      are created.  If the kernel address space is not shared
469  *      between processes, it syncs the pagetable across all
470  *      processes.
471  */
472 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
473 {
474         BUG();
475         return NULL;
476 }
477 EXPORT_SYMBOL_GPL(alloc_vm_area);
478 
479 void free_vm_area(struct vm_struct *area)
480 {
481         BUG();
482 }
483 EXPORT_SYMBOL_GPL(free_vm_area);
484 
485 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
486                    struct page *page)
487 {
488         return -EINVAL;
489 }
490 EXPORT_SYMBOL(vm_insert_page);
491 
492 /*
493  *  sys_brk() for the most part doesn't need the global kernel
494  *  lock, except when an application is doing something nasty
495  *  like trying to un-brk an area that has already been mapped
496  *  to a regular file.  in this case, the unmapping will need
497  *  to invoke file system routines that need the global lock.
498  */
499 SYSCALL_DEFINE1(brk, unsigned long, brk)
500 {
501         struct mm_struct *mm = current->mm;
502 
503         if (brk < mm->start_brk || brk > mm->context.end_brk)
504                 return mm->brk;
505 
506         if (mm->brk == brk)
507                 return mm->brk;
508 
509         /*
510          * Always allow shrinking brk
511          */
512         if (brk <= mm->brk) {
513                 mm->brk = brk;
514                 return brk;
515         }
516 
517         /*
518          * Ok, looks good - let it rip.
519          */
520         flush_icache_range(mm->brk, brk);
521         return mm->brk = brk;
522 }
523 
524 /*
525  * initialise the percpu counter for VM and region record slabs
526  */
527 void __init mmap_init(void)
528 {
529         int ret;
530 
531         ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
532         VM_BUG_ON(ret);
533         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
534 }
535 
536 /*
537  * validate the region tree
538  * - the caller must hold the region lock
539  */
540 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
541 static noinline void validate_nommu_regions(void)
542 {
543         struct vm_region *region, *last;
544         struct rb_node *p, *lastp;
545 
546         lastp = rb_first(&nommu_region_tree);
547         if (!lastp)
548                 return;
549 
550         last = rb_entry(lastp, struct vm_region, vm_rb);
551         BUG_ON(last->vm_end <= last->vm_start);
552         BUG_ON(last->vm_top < last->vm_end);
553 
554         while ((p = rb_next(lastp))) {
555                 region = rb_entry(p, struct vm_region, vm_rb);
556                 last = rb_entry(lastp, struct vm_region, vm_rb);
557 
558                 BUG_ON(region->vm_end <= region->vm_start);
559                 BUG_ON(region->vm_top < region->vm_end);
560                 BUG_ON(region->vm_start < last->vm_top);
561 
562                 lastp = p;
563         }
564 }
565 #else
566 static void validate_nommu_regions(void)
567 {
568 }
569 #endif
570 
571 /*
572  * add a region into the global tree
573  */
574 static void add_nommu_region(struct vm_region *region)
575 {
576         struct vm_region *pregion;
577         struct rb_node **p, *parent;
578 
579         validate_nommu_regions();
580 
581         parent = NULL;
582         p = &nommu_region_tree.rb_node;
583         while (*p) {
584                 parent = *p;
585                 pregion = rb_entry(parent, struct vm_region, vm_rb);
586                 if (region->vm_start < pregion->vm_start)
587                         p = &(*p)->rb_left;
588                 else if (region->vm_start > pregion->vm_start)
589                         p = &(*p)->rb_right;
590                 else if (pregion == region)
591                         return;
592                 else
593                         BUG();
594         }
595 
596         rb_link_node(&region->vm_rb, parent, p);
597         rb_insert_color(&region->vm_rb, &nommu_region_tree);
598 
599         validate_nommu_regions();
600 }
601 
602 /*
603  * delete a region from the global tree
604  */
605 static void delete_nommu_region(struct vm_region *region)
606 {
607         BUG_ON(!nommu_region_tree.rb_node);
608 
609         validate_nommu_regions();
610         rb_erase(&region->vm_rb, &nommu_region_tree);
611         validate_nommu_regions();
612 }
613 
614 /*
615  * free a contiguous series of pages
616  */
617 static void free_page_series(unsigned long from, unsigned long to)
618 {
619         for (; from < to; from += PAGE_SIZE) {
620                 struct page *page = virt_to_page(from);
621 
622                 atomic_long_dec(&mmap_pages_allocated);
623                 put_page(page);
624         }
625 }
626 
627 /*
628  * release a reference to a region
629  * - the caller must hold the region semaphore for writing, which this releases
630  * - the region may not have been added to the tree yet, in which case vm_top
631  *   will equal vm_start
632  */
633 static void __put_nommu_region(struct vm_region *region)
634         __releases(nommu_region_sem)
635 {
636         BUG_ON(!nommu_region_tree.rb_node);
637 
638         if (--region->vm_usage == 0) {
639                 if (region->vm_top > region->vm_start)
640                         delete_nommu_region(region);
641                 up_write(&nommu_region_sem);
642 
643                 if (region->vm_file)
644                         fput(region->vm_file);
645 
646                 /* IO memory and memory shared directly out of the pagecache
647                  * from ramfs/tmpfs mustn't be released here */
648                 if (region->vm_flags & VM_MAPPED_COPY)
649                         free_page_series(region->vm_start, region->vm_top);
650                 kmem_cache_free(vm_region_jar, region);
651         } else {
652                 up_write(&nommu_region_sem);
653         }
654 }
655 
656 /*
657  * release a reference to a region
658  */
659 static void put_nommu_region(struct vm_region *region)
660 {
661         down_write(&nommu_region_sem);
662         __put_nommu_region(region);
663 }
664 
665 /*
666  * update protection on a vma
667  */
668 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
669 {
670 #ifdef CONFIG_MPU
671         struct mm_struct *mm = vma->vm_mm;
672         long start = vma->vm_start & PAGE_MASK;
673         while (start < vma->vm_end) {
674                 protect_page(mm, start, flags);
675                 start += PAGE_SIZE;
676         }
677         update_protections(mm);
678 #endif
679 }
680 
681 /*
682  * add a VMA into a process's mm_struct in the appropriate place in the list
683  * and tree and add to the address space's page tree also if not an anonymous
684  * page
685  * - should be called with mm->mmap_sem held writelocked
686  */
687 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
688 {
689         struct vm_area_struct *pvma, *prev;
690         struct address_space *mapping;
691         struct rb_node **p, *parent, *rb_prev;
692 
693         BUG_ON(!vma->vm_region);
694 
695         mm->map_count++;
696         vma->vm_mm = mm;
697 
698         protect_vma(vma, vma->vm_flags);
699 
700         /* add the VMA to the mapping */
701         if (vma->vm_file) {
702                 mapping = vma->vm_file->f_mapping;
703 
704                 i_mmap_lock_write(mapping);
705                 flush_dcache_mmap_lock(mapping);
706                 vma_interval_tree_insert(vma, &mapping->i_mmap);
707                 flush_dcache_mmap_unlock(mapping);
708                 i_mmap_unlock_write(mapping);
709         }
710 
711         /* add the VMA to the tree */
712         parent = rb_prev = NULL;
713         p = &mm->mm_rb.rb_node;
714         while (*p) {
715                 parent = *p;
716                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
717 
718                 /* sort by: start addr, end addr, VMA struct addr in that order
719                  * (the latter is necessary as we may get identical VMAs) */
720                 if (vma->vm_start < pvma->vm_start)
721                         p = &(*p)->rb_left;
722                 else if (vma->vm_start > pvma->vm_start) {
723                         rb_prev = parent;
724                         p = &(*p)->rb_right;
725                 } else if (vma->vm_end < pvma->vm_end)
726                         p = &(*p)->rb_left;
727                 else if (vma->vm_end > pvma->vm_end) {
728                         rb_prev = parent;
729                         p = &(*p)->rb_right;
730                 } else if (vma < pvma)
731                         p = &(*p)->rb_left;
732                 else if (vma > pvma) {
733                         rb_prev = parent;
734                         p = &(*p)->rb_right;
735                 } else
736                         BUG();
737         }
738 
739         rb_link_node(&vma->vm_rb, parent, p);
740         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
741 
742         /* add VMA to the VMA list also */
743         prev = NULL;
744         if (rb_prev)
745                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
746 
747         __vma_link_list(mm, vma, prev, parent);
748 }
749 
750 /*
751  * delete a VMA from its owning mm_struct and address space
752  */
753 static void delete_vma_from_mm(struct vm_area_struct *vma)
754 {
755         int i;
756         struct address_space *mapping;
757         struct mm_struct *mm = vma->vm_mm;
758         struct task_struct *curr = current;
759 
760         protect_vma(vma, 0);
761 
762         mm->map_count--;
763         for (i = 0; i < VMACACHE_SIZE; i++) {
764                 /* if the vma is cached, invalidate the entire cache */
765                 if (curr->vmacache.vmas[i] == vma) {
766                         vmacache_invalidate(mm);
767                         break;
768                 }
769         }
770 
771         /* remove the VMA from the mapping */
772         if (vma->vm_file) {
773                 mapping = vma->vm_file->f_mapping;
774 
775                 i_mmap_lock_write(mapping);
776                 flush_dcache_mmap_lock(mapping);
777                 vma_interval_tree_remove(vma, &mapping->i_mmap);
778                 flush_dcache_mmap_unlock(mapping);
779                 i_mmap_unlock_write(mapping);
780         }
781 
782         /* remove from the MM's tree and list */
783         rb_erase(&vma->vm_rb, &mm->mm_rb);
784 
785         if (vma->vm_prev)
786                 vma->vm_prev->vm_next = vma->vm_next;
787         else
788                 mm->mmap = vma->vm_next;
789 
790         if (vma->vm_next)
791                 vma->vm_next->vm_prev = vma->vm_prev;
792 }
793 
794 /*
795  * destroy a VMA record
796  */
797 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
798 {
799         if (vma->vm_ops && vma->vm_ops->close)
800                 vma->vm_ops->close(vma);
801         if (vma->vm_file)
802                 fput(vma->vm_file);
803         put_nommu_region(vma->vm_region);
804         kmem_cache_free(vm_area_cachep, vma);
805 }
806 
807 /*
808  * look up the first VMA in which addr resides, NULL if none
809  * - should be called with mm->mmap_sem at least held readlocked
810  */
811 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
812 {
813         struct vm_area_struct *vma;
814 
815         /* check the cache first */
816         vma = vmacache_find(mm, addr);
817         if (likely(vma))
818                 return vma;
819 
820         /* trawl the list (there may be multiple mappings in which addr
821          * resides) */
822         for (vma = mm->mmap; vma; vma = vma->vm_next) {
823                 if (vma->vm_start > addr)
824                         return NULL;
825                 if (vma->vm_end > addr) {
826                         vmacache_update(addr, vma);
827                         return vma;
828                 }
829         }
830 
831         return NULL;
832 }
833 EXPORT_SYMBOL(find_vma);
834 
835 /*
836  * find a VMA
837  * - we don't extend stack VMAs under NOMMU conditions
838  */
839 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
840 {
841         return find_vma(mm, addr);
842 }
843 
844 /*
845  * expand a stack to a given address
846  * - not supported under NOMMU conditions
847  */
848 int expand_stack(struct vm_area_struct *vma, unsigned long address)
849 {
850         return -ENOMEM;
851 }
852 
853 /*
854  * look up the first VMA exactly that exactly matches addr
855  * - should be called with mm->mmap_sem at least held readlocked
856  */
857 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
858                                              unsigned long addr,
859                                              unsigned long len)
860 {
861         struct vm_area_struct *vma;
862         unsigned long end = addr + len;
863 
864         /* check the cache first */
865         vma = vmacache_find_exact(mm, addr, end);
866         if (vma)
867                 return vma;
868 
869         /* trawl the list (there may be multiple mappings in which addr
870          * resides) */
871         for (vma = mm->mmap; vma; vma = vma->vm_next) {
872                 if (vma->vm_start < addr)
873                         continue;
874                 if (vma->vm_start > addr)
875                         return NULL;
876                 if (vma->vm_end == end) {
877                         vmacache_update(addr, vma);
878                         return vma;
879                 }
880         }
881 
882         return NULL;
883 }
884 
885 /*
886  * determine whether a mapping should be permitted and, if so, what sort of
887  * mapping we're capable of supporting
888  */
889 static int validate_mmap_request(struct file *file,
890                                  unsigned long addr,
891                                  unsigned long len,
892                                  unsigned long prot,
893                                  unsigned long flags,
894                                  unsigned long pgoff,
895                                  unsigned long *_capabilities)
896 {
897         unsigned long capabilities, rlen;
898         int ret;
899 
900         /* do the simple checks first */
901         if (flags & MAP_FIXED)
902                 return -EINVAL;
903 
904         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
905             (flags & MAP_TYPE) != MAP_SHARED)
906                 return -EINVAL;
907 
908         if (!len)
909                 return -EINVAL;
910 
911         /* Careful about overflows.. */
912         rlen = PAGE_ALIGN(len);
913         if (!rlen || rlen > TASK_SIZE)
914                 return -ENOMEM;
915 
916         /* offset overflow? */
917         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
918                 return -EOVERFLOW;
919 
920         if (file) {
921                 /* files must support mmap */
922                 if (!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                 if (file->f_op->mmap_capabilities) {
930                         capabilities = file->f_op->mmap_capabilities(file);
931                 } else {
932                         /* no explicit capabilities set, so assume some
933                          * defaults */
934                         switch (file_inode(file)->i_mode & S_IFMT) {
935                         case S_IFREG:
936                         case S_IFBLK:
937                                 capabilities = NOMMU_MAP_COPY;
938                                 break;
939 
940                         case S_IFCHR:
941                                 capabilities =
942                                         NOMMU_MAP_DIRECT |
943                                         NOMMU_MAP_READ |
944                                         NOMMU_MAP_WRITE;
945                                 break;
946 
947                         default:
948                                 return -EINVAL;
949                         }
950                 }
951 
952                 /* eliminate any capabilities that we can't support on this
953                  * device */
954                 if (!file->f_op->get_unmapped_area)
955                         capabilities &= ~NOMMU_MAP_DIRECT;
956                 if (!(file->f_mode & FMODE_CAN_READ))
957                         capabilities &= ~NOMMU_MAP_COPY;
958 
959                 /* The file shall have been opened with read permission. */
960                 if (!(file->f_mode & FMODE_READ))
961                         return -EACCES;
962 
963                 if (flags & MAP_SHARED) {
964                         /* do checks for writing, appending and locking */
965                         if ((prot & PROT_WRITE) &&
966                             !(file->f_mode & FMODE_WRITE))
967                                 return -EACCES;
968 
969                         if (IS_APPEND(file_inode(file)) &&
970                             (file->f_mode & FMODE_WRITE))
971                                 return -EACCES;
972 
973                         if (locks_verify_locked(file))
974                                 return -EAGAIN;
975 
976                         if (!(capabilities & NOMMU_MAP_DIRECT))
977                                 return -ENODEV;
978 
979                         /* we mustn't privatise shared mappings */
980                         capabilities &= ~NOMMU_MAP_COPY;
981                 } else {
982                         /* we're going to read the file into private memory we
983                          * allocate */
984                         if (!(capabilities & NOMMU_MAP_COPY))
985                                 return -ENODEV;
986 
987                         /* we don't permit a private writable mapping to be
988                          * shared with the backing device */
989                         if (prot & PROT_WRITE)
990                                 capabilities &= ~NOMMU_MAP_DIRECT;
991                 }
992 
993                 if (capabilities & NOMMU_MAP_DIRECT) {
994                         if (((prot & PROT_READ)  && !(capabilities & NOMMU_MAP_READ))  ||
995                             ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
996                             ((prot & PROT_EXEC)  && !(capabilities & NOMMU_MAP_EXEC))
997                             ) {
998                                 capabilities &= ~NOMMU_MAP_DIRECT;
999                                 if (flags & MAP_SHARED) {
1000                                         pr_warn("MAP_SHARED not completely supported on !MMU\n");
1001                                         return -EINVAL;
1002                                 }
1003                         }
1004                 }
1005 
1006                 /* handle executable mappings and implied executable
1007                  * mappings */
1008                 if (path_noexec(&file->f_path)) {
1009                         if (prot & PROT_EXEC)
1010                                 return -EPERM;
1011                 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1012                         /* handle implication of PROT_EXEC by PROT_READ */
1013                         if (current->personality & READ_IMPLIES_EXEC) {
1014                                 if (capabilities & NOMMU_MAP_EXEC)
1015                                         prot |= PROT_EXEC;
1016                         }
1017                 } else if ((prot & PROT_READ) &&
1018                          (prot & PROT_EXEC) &&
1019                          !(capabilities & NOMMU_MAP_EXEC)
1020                          ) {
1021                         /* backing file is not executable, try to copy */
1022                         capabilities &= ~NOMMU_MAP_DIRECT;
1023                 }
1024         } else {
1025                 /* anonymous mappings are always memory backed and can be
1026                  * privately mapped
1027                  */
1028                 capabilities = NOMMU_MAP_COPY;
1029 
1030                 /* handle PROT_EXEC implication by PROT_READ */
1031                 if ((prot & PROT_READ) &&
1032                     (current->personality & READ_IMPLIES_EXEC))
1033                         prot |= PROT_EXEC;
1034         }
1035 
1036         /* allow the security API to have its say */
1037         ret = security_mmap_addr(addr);
1038         if (ret < 0)
1039                 return ret;
1040 
1041         /* looks okay */
1042         *_capabilities = capabilities;
1043         return 0;
1044 }
1045 
1046 /*
1047  * we've determined that we can make the mapping, now translate what we
1048  * now know into VMA flags
1049  */
1050 static unsigned long determine_vm_flags(struct file *file,
1051                                         unsigned long prot,
1052                                         unsigned long flags,
1053                                         unsigned long capabilities)
1054 {
1055         unsigned long vm_flags;
1056 
1057         vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
1058         /* vm_flags |= mm->def_flags; */
1059 
1060         if (!(capabilities & NOMMU_MAP_DIRECT)) {
1061                 /* attempt to share read-only copies of mapped file chunks */
1062                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1063                 if (file && !(prot & PROT_WRITE))
1064                         vm_flags |= VM_MAYSHARE;
1065         } else {
1066                 /* overlay a shareable mapping on the backing device or inode
1067                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1068                  * romfs/cramfs */
1069                 vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
1070                 if (flags & MAP_SHARED)
1071                         vm_flags |= VM_SHARED;
1072         }
1073 
1074         /* refuse to let anyone share private mappings with this process if
1075          * it's being traced - otherwise breakpoints set in it may interfere
1076          * with another untraced process
1077          */
1078         if ((flags & MAP_PRIVATE) && current->ptrace)
1079                 vm_flags &= ~VM_MAYSHARE;
1080 
1081         return vm_flags;
1082 }
1083 
1084 /*
1085  * set up a shared mapping on a file (the driver or filesystem provides and
1086  * pins the storage)
1087  */
1088 static int do_mmap_shared_file(struct vm_area_struct *vma)
1089 {
1090         int ret;
1091 
1092         ret = call_mmap(vma->vm_file, vma);
1093         if (ret == 0) {
1094                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1095                 return 0;
1096         }
1097         if (ret != -ENOSYS)
1098                 return ret;
1099 
1100         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1101          * opposed to tried but failed) so we can only give a suitable error as
1102          * it's not possible to make a private copy if MAP_SHARED was given */
1103         return -ENODEV;
1104 }
1105 
1106 /*
1107  * set up a private mapping or an anonymous shared mapping
1108  */
1109 static int do_mmap_private(struct vm_area_struct *vma,
1110                            struct vm_region *region,
1111                            unsigned long len,
1112                            unsigned long capabilities)
1113 {
1114         unsigned long total, point;
1115         void *base;
1116         int ret, order;
1117 
1118         /* invoke the file's mapping function so that it can keep track of
1119          * shared mappings on devices or memory
1120          * - VM_MAYSHARE will be set if it may attempt to share
1121          */
1122         if (capabilities & NOMMU_MAP_DIRECT) {
1123                 ret = call_mmap(vma->vm_file, vma);
1124                 if (ret == 0) {
1125                         /* shouldn't return success if we're not sharing */
1126                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1127                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1128                         return 0;
1129                 }
1130                 if (ret != -ENOSYS)
1131                         return ret;
1132 
1133                 /* getting an ENOSYS error indicates that direct mmap isn't
1134                  * possible (as opposed to tried but failed) so we'll try to
1135                  * make a private copy of the data and map that instead */
1136         }
1137 
1138 
1139         /* allocate some memory to hold the mapping
1140          * - note that this may not return a page-aligned address if the object
1141          *   we're allocating is smaller than a page
1142          */
1143         order = get_order(len);
1144         total = 1 << order;
1145         point = len >> PAGE_SHIFT;
1146 
1147         /* we don't want to allocate a power-of-2 sized page set */
1148         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
1149                 total = point;
1150 
1151         base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
1152         if (!base)
1153                 goto enomem;
1154 
1155         atomic_long_add(total, &mmap_pages_allocated);
1156 
1157         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1158         region->vm_start = (unsigned long) base;
1159         region->vm_end   = region->vm_start + len;
1160         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1161 
1162         vma->vm_start = region->vm_start;
1163         vma->vm_end   = region->vm_start + len;
1164 
1165         if (vma->vm_file) {
1166                 /* read the contents of a file into the copy */
1167                 loff_t fpos;
1168 
1169                 fpos = vma->vm_pgoff;
1170                 fpos <<= PAGE_SHIFT;
1171 
1172                 ret = kernel_read(vma->vm_file, base, len, &fpos);
1173                 if (ret < 0)
1174                         goto error_free;
1175 
1176                 /* clear the last little bit */
1177                 if (ret < len)
1178                         memset(base + ret, 0, len - ret);
1179 
1180         }
1181 
1182         return 0;
1183 
1184 error_free:
1185         free_page_series(region->vm_start, region->vm_top);
1186         region->vm_start = vma->vm_start = 0;
1187         region->vm_end   = vma->vm_end = 0;
1188         region->vm_top   = 0;
1189         return ret;
1190 
1191 enomem:
1192         pr_err("Allocation of length %lu from process %d (%s) failed\n",
1193                len, current->pid, current->comm);
1194         show_free_areas(0, NULL);
1195         return -ENOMEM;
1196 }
1197 
1198 /*
1199  * handle mapping creation for uClinux
1200  */
1201 unsigned long do_mmap(struct file *file,
1202                         unsigned long addr,
1203                         unsigned long len,
1204                         unsigned long prot,
1205                         unsigned long flags,
1206                         vm_flags_t vm_flags,
1207                         unsigned long pgoff,
1208                         unsigned long *populate,
1209                         struct list_head *uf)
1210 {
1211         struct vm_area_struct *vma;
1212         struct vm_region *region;
1213         struct rb_node *rb;
1214         unsigned long capabilities, result;
1215         int ret;
1216 
1217         *populate = 0;
1218 
1219         /* decide whether we should attempt the mapping, and if so what sort of
1220          * mapping */
1221         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1222                                     &capabilities);
1223         if (ret < 0)
1224                 return ret;
1225 
1226         /* we ignore the address hint */
1227         addr = 0;
1228         len = PAGE_ALIGN(len);
1229 
1230         /* we've determined that we can make the mapping, now translate what we
1231          * now know into VMA flags */
1232         vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1233 
1234         /* we're going to need to record the mapping */
1235         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1236         if (!region)
1237                 goto error_getting_region;
1238 
1239         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1240         if (!vma)
1241                 goto error_getting_vma;
1242 
1243         region->vm_usage = 1;
1244         region->vm_flags = vm_flags;
1245         region->vm_pgoff = pgoff;
1246 
1247         INIT_LIST_HEAD(&vma->anon_vma_chain);
1248         vma->vm_flags = vm_flags;
1249         vma->vm_pgoff = pgoff;
1250 
1251         if (file) {
1252                 region->vm_file = get_file(file);
1253                 vma->vm_file = get_file(file);
1254         }
1255 
1256         down_write(&nommu_region_sem);
1257 
1258         /* if we want to share, we need to check for regions created by other
1259          * mmap() calls that overlap with our proposed mapping
1260          * - we can only share with a superset match on most regular files
1261          * - shared mappings on character devices and memory backed files are
1262          *   permitted to overlap inexactly as far as we are concerned for in
1263          *   these cases, sharing is handled in the driver or filesystem rather
1264          *   than here
1265          */
1266         if (vm_flags & VM_MAYSHARE) {
1267                 struct vm_region *pregion;
1268                 unsigned long pglen, rpglen, pgend, rpgend, start;
1269 
1270                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1271                 pgend = pgoff + pglen;
1272 
1273                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1274                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1275 
1276                         if (!(pregion->vm_flags & VM_MAYSHARE))
1277                                 continue;
1278 
1279                         /* search for overlapping mappings on the same file */
1280                         if (file_inode(pregion->vm_file) !=
1281                             file_inode(file))
1282                                 continue;
1283 
1284                         if (pregion->vm_pgoff >= pgend)
1285                                 continue;
1286 
1287                         rpglen = pregion->vm_end - pregion->vm_start;
1288                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1289                         rpgend = pregion->vm_pgoff + rpglen;
1290                         if (pgoff >= rpgend)
1291                                 continue;
1292 
1293                         /* handle inexactly overlapping matches between
1294                          * mappings */
1295                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1296                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1297                                 /* new mapping is not a subset of the region */
1298                                 if (!(capabilities & NOMMU_MAP_DIRECT))
1299                                         goto sharing_violation;
1300                                 continue;
1301                         }
1302 
1303                         /* we've found a region we can share */
1304                         pregion->vm_usage++;
1305                         vma->vm_region = pregion;
1306                         start = pregion->vm_start;
1307                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1308                         vma->vm_start = start;
1309                         vma->vm_end = start + len;
1310 
1311                         if (pregion->vm_flags & VM_MAPPED_COPY)
1312                                 vma->vm_flags |= VM_MAPPED_COPY;
1313                         else {
1314                                 ret = do_mmap_shared_file(vma);
1315                                 if (ret < 0) {
1316                                         vma->vm_region = NULL;
1317                                         vma->vm_start = 0;
1318                                         vma->vm_end = 0;
1319                                         pregion->vm_usage--;
1320                                         pregion = NULL;
1321                                         goto error_just_free;
1322                                 }
1323                         }
1324                         fput(region->vm_file);
1325                         kmem_cache_free(vm_region_jar, region);
1326                         region = pregion;
1327                         result = start;
1328                         goto share;
1329                 }
1330 
1331                 /* obtain the address at which to make a shared mapping
1332                  * - this is the hook for quasi-memory character devices to
1333                  *   tell us the location of a shared mapping
1334                  */
1335                 if (capabilities & NOMMU_MAP_DIRECT) {
1336                         addr = file->f_op->get_unmapped_area(file, addr, len,
1337                                                              pgoff, flags);
1338                         if (IS_ERR_VALUE(addr)) {
1339                                 ret = addr;
1340                                 if (ret != -ENOSYS)
1341                                         goto error_just_free;
1342 
1343                                 /* the driver refused to tell us where to site
1344                                  * the mapping so we'll have to attempt to copy
1345                                  * it */
1346                                 ret = -ENODEV;
1347                                 if (!(capabilities & NOMMU_MAP_COPY))
1348                                         goto error_just_free;
1349 
1350                                 capabilities &= ~NOMMU_MAP_DIRECT;
1351                         } else {
1352                                 vma->vm_start = region->vm_start = addr;
1353                                 vma->vm_end = region->vm_end = addr + len;
1354                         }
1355                 }
1356         }
1357 
1358         vma->vm_region = region;
1359 
1360         /* set up the mapping
1361          * - the region is filled in if NOMMU_MAP_DIRECT is still set
1362          */
1363         if (file && vma->vm_flags & VM_SHARED)
1364                 ret = do_mmap_shared_file(vma);
1365         else
1366                 ret = do_mmap_private(vma, region, len, capabilities);
1367         if (ret < 0)
1368                 goto error_just_free;
1369         add_nommu_region(region);
1370 
1371         /* clear anonymous mappings that don't ask for uninitialized data */
1372         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1373                 memset((void *)region->vm_start, 0,
1374                        region->vm_end - region->vm_start);
1375 
1376         /* okay... we have a mapping; now we have to register it */
1377         result = vma->vm_start;
1378 
1379         current->mm->total_vm += len >> PAGE_SHIFT;
1380 
1381 share:
1382         add_vma_to_mm(current->mm, vma);
1383 
1384         /* we flush the region from the icache only when the first executable
1385          * mapping of it is made  */
1386         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1387                 flush_icache_range(region->vm_start, region->vm_end);
1388                 region->vm_icache_flushed = true;
1389         }
1390 
1391         up_write(&nommu_region_sem);
1392 
1393         return result;
1394 
1395 error_just_free:
1396         up_write(&nommu_region_sem);
1397 error:
1398         if (region->vm_file)
1399                 fput(region->vm_file);
1400         kmem_cache_free(vm_region_jar, region);
1401         if (vma->vm_file)
1402                 fput(vma->vm_file);
1403         kmem_cache_free(vm_area_cachep, vma);
1404         return ret;
1405 
1406 sharing_violation:
1407         up_write(&nommu_region_sem);
1408         pr_warn("Attempt to share mismatched mappings\n");
1409         ret = -EINVAL;
1410         goto error;
1411 
1412 error_getting_vma:
1413         kmem_cache_free(vm_region_jar, region);
1414         pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1415                         len, current->pid);
1416         show_free_areas(0, NULL);
1417         return -ENOMEM;
1418 
1419 error_getting_region:
1420         pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1421                         len, current->pid);
1422         show_free_areas(0, NULL);
1423         return -ENOMEM;
1424 }
1425 
1426 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1427                 unsigned long, prot, unsigned long, flags,
1428                 unsigned long, fd, unsigned long, pgoff)
1429 {
1430         struct file *file = NULL;
1431         unsigned long retval = -EBADF;
1432 
1433         audit_mmap_fd(fd, flags);
1434         if (!(flags & MAP_ANONYMOUS)) {
1435                 file = fget(fd);
1436                 if (!file)
1437                         goto out;
1438         }
1439 
1440         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1441 
1442         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1443 
1444         if (file)
1445                 fput(file);
1446 out:
1447         return retval;
1448 }
1449 
1450 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1451 struct mmap_arg_struct {
1452         unsigned long addr;
1453         unsigned long len;
1454         unsigned long prot;
1455         unsigned long flags;
1456         unsigned long fd;
1457         unsigned long offset;
1458 };
1459 
1460 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1461 {
1462         struct mmap_arg_struct a;
1463 
1464         if (copy_from_user(&a, arg, sizeof(a)))
1465                 return -EFAULT;
1466         if (offset_in_page(a.offset))
1467                 return -EINVAL;
1468 
1469         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1470                               a.offset >> PAGE_SHIFT);
1471 }
1472 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1473 
1474 /*
1475  * split a vma into two pieces at address 'addr', a new vma is allocated either
1476  * for the first part or the tail.
1477  */
1478 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1479               unsigned long addr, int new_below)
1480 {
1481         struct vm_area_struct *new;
1482         struct vm_region *region;
1483         unsigned long npages;
1484 
1485         /* we're only permitted to split anonymous regions (these should have
1486          * only a single usage on the region) */
1487         if (vma->vm_file)
1488                 return -ENOMEM;
1489 
1490         if (mm->map_count >= sysctl_max_map_count)
1491                 return -ENOMEM;
1492 
1493         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1494         if (!region)
1495                 return -ENOMEM;
1496 
1497         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1498         if (!new) {
1499                 kmem_cache_free(vm_region_jar, region);
1500                 return -ENOMEM;
1501         }
1502 
1503         /* most fields are the same, copy all, and then fixup */
1504         *new = *vma;
1505         *region = *vma->vm_region;
1506         new->vm_region = region;
1507 
1508         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1509 
1510         if (new_below) {
1511                 region->vm_top = region->vm_end = new->vm_end = addr;
1512         } else {
1513                 region->vm_start = new->vm_start = addr;
1514                 region->vm_pgoff = new->vm_pgoff += npages;
1515         }
1516 
1517         if (new->vm_ops && new->vm_ops->open)
1518                 new->vm_ops->open(new);
1519 
1520         delete_vma_from_mm(vma);
1521         down_write(&nommu_region_sem);
1522         delete_nommu_region(vma->vm_region);
1523         if (new_below) {
1524                 vma->vm_region->vm_start = vma->vm_start = addr;
1525                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1526         } else {
1527                 vma->vm_region->vm_end = vma->vm_end = addr;
1528                 vma->vm_region->vm_top = addr;
1529         }
1530         add_nommu_region(vma->vm_region);
1531         add_nommu_region(new->vm_region);
1532         up_write(&nommu_region_sem);
1533         add_vma_to_mm(mm, vma);
1534         add_vma_to_mm(mm, new);
1535         return 0;
1536 }
1537 
1538 /*
1539  * shrink a VMA by removing the specified chunk from either the beginning or
1540  * the end
1541  */
1542 static int shrink_vma(struct mm_struct *mm,
1543                       struct vm_area_struct *vma,
1544                       unsigned long from, unsigned long to)
1545 {
1546         struct vm_region *region;
1547 
1548         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1549          * and list */
1550         delete_vma_from_mm(vma);
1551         if (from > vma->vm_start)
1552                 vma->vm_end = from;
1553         else
1554                 vma->vm_start = to;
1555         add_vma_to_mm(mm, vma);
1556 
1557         /* cut the backing region down to size */
1558         region = vma->vm_region;
1559         BUG_ON(region->vm_usage != 1);
1560 
1561         down_write(&nommu_region_sem);
1562         delete_nommu_region(region);
1563         if (from > region->vm_start) {
1564                 to = region->vm_top;
1565                 region->vm_top = region->vm_end = from;
1566         } else {
1567                 region->vm_start = to;
1568         }
1569         add_nommu_region(region);
1570         up_write(&nommu_region_sem);
1571 
1572         free_page_series(from, to);
1573         return 0;
1574 }
1575 
1576 /*
1577  * release a mapping
1578  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1579  *   VMA, though it need not cover the whole VMA
1580  */
1581 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
1582 {
1583         struct vm_area_struct *vma;
1584         unsigned long end;
1585         int ret;
1586 
1587         len = PAGE_ALIGN(len);
1588         if (len == 0)
1589                 return -EINVAL;
1590 
1591         end = start + len;
1592 
1593         /* find the first potentially overlapping VMA */
1594         vma = find_vma(mm, start);
1595         if (!vma) {
1596                 static int limit;
1597                 if (limit < 5) {
1598                         pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1599                                         current->pid, current->comm,
1600                                         start, start + len - 1);
1601                         limit++;
1602                 }
1603                 return -EINVAL;
1604         }
1605 
1606         /* we're allowed to split an anonymous VMA but not a file-backed one */
1607         if (vma->vm_file) {
1608                 do {
1609                         if (start > vma->vm_start)
1610                                 return -EINVAL;
1611                         if (end == vma->vm_end)
1612                                 goto erase_whole_vma;
1613                         vma = vma->vm_next;
1614                 } while (vma);
1615                 return -EINVAL;
1616         } else {
1617                 /* the chunk must be a subset of the VMA found */
1618                 if (start == vma->vm_start && end == vma->vm_end)
1619                         goto erase_whole_vma;
1620                 if (start < vma->vm_start || end > vma->vm_end)
1621                         return -EINVAL;
1622                 if (offset_in_page(start))
1623                         return -EINVAL;
1624                 if (end != vma->vm_end && offset_in_page(end))
1625                         return -EINVAL;
1626                 if (start != vma->vm_start && end != vma->vm_end) {
1627                         ret = split_vma(mm, vma, start, 1);
1628                         if (ret < 0)
1629                                 return ret;
1630                 }
1631                 return shrink_vma(mm, vma, start, end);
1632         }
1633 
1634 erase_whole_vma:
1635         delete_vma_from_mm(vma);
1636         delete_vma(mm, vma);
1637         return 0;
1638 }
1639 EXPORT_SYMBOL(do_munmap);
1640 
1641 int vm_munmap(unsigned long addr, size_t len)
1642 {
1643         struct mm_struct *mm = current->mm;
1644         int ret;
1645 
1646         down_write(&mm->mmap_sem);
1647         ret = do_munmap(mm, addr, len, NULL);
1648         up_write(&mm->mmap_sem);
1649         return ret;
1650 }
1651 EXPORT_SYMBOL(vm_munmap);
1652 
1653 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1654 {
1655         return vm_munmap(addr, len);
1656 }
1657 
1658 /*
1659  * release all the mappings made in a process's VM space
1660  */
1661 void exit_mmap(struct mm_struct *mm)
1662 {
1663         struct vm_area_struct *vma;
1664 
1665         if (!mm)
1666                 return;
1667 
1668         mm->total_vm = 0;
1669 
1670         while ((vma = mm->mmap)) {
1671                 mm->mmap = vma->vm_next;
1672                 delete_vma_from_mm(vma);
1673                 delete_vma(mm, vma);
1674                 cond_resched();
1675         }
1676 }
1677 
1678 int vm_brk(unsigned long addr, unsigned long len)
1679 {
1680         return -ENOMEM;
1681 }
1682 
1683 /*
1684  * expand (or shrink) an existing mapping, potentially moving it at the same
1685  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1686  *
1687  * under NOMMU conditions, we only permit changing a mapping's size, and only
1688  * as long as it stays within the region allocated by do_mmap_private() and the
1689  * block is not shareable
1690  *
1691  * MREMAP_FIXED is not supported under NOMMU conditions
1692  */
1693 static unsigned long do_mremap(unsigned long addr,
1694                         unsigned long old_len, unsigned long new_len,
1695                         unsigned long flags, unsigned long new_addr)
1696 {
1697         struct vm_area_struct *vma;
1698 
1699         /* insanity checks first */
1700         old_len = PAGE_ALIGN(old_len);
1701         new_len = PAGE_ALIGN(new_len);
1702         if (old_len == 0 || new_len == 0)
1703                 return (unsigned long) -EINVAL;
1704 
1705         if (offset_in_page(addr))
1706                 return -EINVAL;
1707 
1708         if (flags & MREMAP_FIXED && new_addr != addr)
1709                 return (unsigned long) -EINVAL;
1710 
1711         vma = find_vma_exact(current->mm, addr, old_len);
1712         if (!vma)
1713                 return (unsigned long) -EINVAL;
1714 
1715         if (vma->vm_end != vma->vm_start + old_len)
1716                 return (unsigned long) -EFAULT;
1717 
1718         if (vma->vm_flags & VM_MAYSHARE)
1719                 return (unsigned long) -EPERM;
1720 
1721         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1722                 return (unsigned long) -ENOMEM;
1723 
1724         /* all checks complete - do it */
1725         vma->vm_end = vma->vm_start + new_len;
1726         return vma->vm_start;
1727 }
1728 
1729 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1730                 unsigned long, new_len, unsigned long, flags,
1731                 unsigned long, new_addr)
1732 {
1733         unsigned long ret;
1734 
1735         down_write(&current->mm->mmap_sem);
1736         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1737         up_write(&current->mm->mmap_sem);
1738         return ret;
1739 }
1740 
1741 struct page *follow_page_mask(struct vm_area_struct *vma,
1742                               unsigned long address, unsigned int flags,
1743                               unsigned int *page_mask)
1744 {
1745         *page_mask = 0;
1746         return NULL;
1747 }
1748 
1749 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1750                 unsigned long pfn, unsigned long size, pgprot_t prot)
1751 {
1752         if (addr != (pfn << PAGE_SHIFT))
1753                 return -EINVAL;
1754 
1755         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1756         return 0;
1757 }
1758 EXPORT_SYMBOL(remap_pfn_range);
1759 
1760 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1761 {
1762         unsigned long pfn = start >> PAGE_SHIFT;
1763         unsigned long vm_len = vma->vm_end - vma->vm_start;
1764 
1765         pfn += vma->vm_pgoff;
1766         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1767 }
1768 EXPORT_SYMBOL(vm_iomap_memory);
1769 
1770 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1771                         unsigned long pgoff)
1772 {
1773         unsigned int size = vma->vm_end - vma->vm_start;
1774 
1775         if (!(vma->vm_flags & VM_USERMAP))
1776                 return -EINVAL;
1777 
1778         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1779         vma->vm_end = vma->vm_start + size;
1780 
1781         return 0;
1782 }
1783 EXPORT_SYMBOL(remap_vmalloc_range);
1784 
1785 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1786         unsigned long len, unsigned long pgoff, unsigned long flags)
1787 {
1788         return -ENOMEM;
1789 }
1790 
1791 void unmap_mapping_range(struct address_space *mapping,
1792                          loff_t const holebegin, loff_t const holelen,
1793                          int even_cows)
1794 {
1795 }
1796 EXPORT_SYMBOL(unmap_mapping_range);
1797 
1798 int filemap_fault(struct vm_fault *vmf)
1799 {
1800         BUG();
1801         return 0;
1802 }
1803 EXPORT_SYMBOL(filemap_fault);
1804 
1805 void filemap_map_pages(struct vm_fault *vmf,
1806                 pgoff_t start_pgoff, pgoff_t end_pgoff)
1807 {
1808         BUG();
1809 }
1810 EXPORT_SYMBOL(filemap_map_pages);
1811 
1812 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1813                 unsigned long addr, void *buf, int len, unsigned int gup_flags)
1814 {
1815         struct vm_area_struct *vma;
1816         int write = gup_flags & FOLL_WRITE;
1817 
1818         down_read(&mm->mmap_sem);
1819 
1820         /* the access must start within one of the target process's mappings */
1821         vma = find_vma(mm, addr);
1822         if (vma) {
1823                 /* don't overrun this mapping */
1824                 if (addr + len >= vma->vm_end)
1825                         len = vma->vm_end - addr;
1826 
1827                 /* only read or write mappings where it is permitted */
1828                 if (write && vma->vm_flags & VM_MAYWRITE)
1829                         copy_to_user_page(vma, NULL, addr,
1830                                          (void *) addr, buf, len);
1831                 else if (!write && vma->vm_flags & VM_MAYREAD)
1832                         copy_from_user_page(vma, NULL, addr,
1833                                             buf, (void *) addr, len);
1834                 else
1835                         len = 0;
1836         } else {
1837                 len = 0;
1838         }
1839 
1840         up_read(&mm->mmap_sem);
1841 
1842         return len;
1843 }
1844 
1845 /**
1846  * @access_remote_vm - access another process' address space
1847  * @mm:         the mm_struct of the target address space
1848  * @addr:       start address to access
1849  * @buf:        source or destination buffer
1850  * @len:        number of bytes to transfer
1851  * @gup_flags:  flags modifying lookup behaviour
1852  *
1853  * The caller must hold a reference on @mm.
1854  */
1855 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1856                 void *buf, int len, unsigned int gup_flags)
1857 {
1858         return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
1859 }
1860 
1861 /*
1862  * Access another process' address space.
1863  * - source/target buffer must be kernel space
1864  */
1865 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
1866                 unsigned int gup_flags)
1867 {
1868         struct mm_struct *mm;
1869 
1870         if (addr + len < addr)
1871                 return 0;
1872 
1873         mm = get_task_mm(tsk);
1874         if (!mm)
1875                 return 0;
1876 
1877         len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
1878 
1879         mmput(mm);
1880         return len;
1881 }
1882 EXPORT_SYMBOL_GPL(access_process_vm);
1883 
1884 /**
1885  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1886  * @inode: The inode to check
1887  * @size: The current filesize of the inode
1888  * @newsize: The proposed filesize of the inode
1889  *
1890  * Check the shared mappings on an inode on behalf of a shrinking truncate to
1891  * make sure that that any outstanding VMAs aren't broken and then shrink the
1892  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1893  * automatically grant mappings that are too large.
1894  */
1895 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1896                                 size_t newsize)
1897 {
1898         struct vm_area_struct *vma;
1899         struct vm_region *region;
1900         pgoff_t low, high;
1901         size_t r_size, r_top;
1902 
1903         low = newsize >> PAGE_SHIFT;
1904         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1905 
1906         down_write(&nommu_region_sem);
1907         i_mmap_lock_read(inode->i_mapping);
1908 
1909         /* search for VMAs that fall within the dead zone */
1910         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1911                 /* found one - only interested if it's shared out of the page
1912                  * cache */
1913                 if (vma->vm_flags & VM_SHARED) {
1914                         i_mmap_unlock_read(inode->i_mapping);
1915                         up_write(&nommu_region_sem);
1916                         return -ETXTBSY; /* not quite true, but near enough */
1917                 }
1918         }
1919 
1920         /* reduce any regions that overlap the dead zone - if in existence,
1921          * these will be pointed to by VMAs that don't overlap the dead zone
1922          *
1923          * we don't check for any regions that start beyond the EOF as there
1924          * shouldn't be any
1925          */
1926         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1927                 if (!(vma->vm_flags & VM_SHARED))
1928                         continue;
1929 
1930                 region = vma->vm_region;
1931                 r_size = region->vm_top - region->vm_start;
1932                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1933 
1934                 if (r_top > newsize) {
1935                         region->vm_top -= r_top - newsize;
1936                         if (region->vm_end > region->vm_top)
1937                                 region->vm_end = region->vm_top;
1938                 }
1939         }
1940 
1941         i_mmap_unlock_read(inode->i_mapping);
1942         up_write(&nommu_region_sem);
1943         return 0;
1944 }
1945 
1946 /*
1947  * Initialise sysctl_user_reserve_kbytes.
1948  *
1949  * This is intended to prevent a user from starting a single memory hogging
1950  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1951  * mode.
1952  *
1953  * The default value is min(3% of free memory, 128MB)
1954  * 128MB is enough to recover with sshd/login, bash, and top/kill.
1955  */
1956 static int __meminit init_user_reserve(void)
1957 {
1958         unsigned long free_kbytes;
1959 
1960         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1961 
1962         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1963         return 0;
1964 }
1965 subsys_initcall(init_user_reserve);
1966 
1967 /*
1968  * Initialise sysctl_admin_reserve_kbytes.
1969  *
1970  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1971  * to log in and kill a memory hogging process.
1972  *
1973  * Systems with more than 256MB will reserve 8MB, enough to recover
1974  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1975  * only reserve 3% of free pages by default.
1976  */
1977 static int __meminit init_admin_reserve(void)
1978 {
1979         unsigned long free_kbytes;
1980 
1981         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1982 
1983         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1984         return 0;
1985 }
1986 subsys_initcall(init_admin_reserve);
1987 

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