blob: b76f3ee0abe015a85f36ff4b2599cff21d3c3efd [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 *
David Howells8feae132009-01-08 12:04:47 +00009 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * 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>
Paul Mundteb6434d2009-01-21 17:45:47 +090013 * Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014 */
15
David Howellsf2b85442007-10-29 13:15:39 +000016#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#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>
Roland McGrathfa8e26c2008-07-25 19:45:50 -070025#include <linux/tracehook.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/blkdev.h>
27#include <linux/backing-dev.h>
28#include <linux/mount.h>
29#include <linux/personality.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
32
33#include <asm/uaccess.h>
34#include <asm/tlb.h>
35#include <asm/tlbflush.h>
Bernd Schmidteb8cdec2009-09-21 17:03:57 -070036#include <asm/mmu_context.h>
David Howells8feae132009-01-08 12:04:47 +000037#include "internal.h"
38
39static inline __attribute__((format(printf, 1, 2)))
40void no_printk(const char *fmt, ...)
41{
42}
43
44#if 0
45#define kenter(FMT, ...) \
46 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
47#define kleave(FMT, ...) \
48 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
49#define kdebug(FMT, ...) \
50 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
51#else
52#define kenter(FMT, ...) \
53 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
54#define kleave(FMT, ...) \
55 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
56#define kdebug(FMT, ...) \
57 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
58#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60void *high_memory;
61struct page *mem_map;
62unsigned long max_mapnr;
63unsigned long num_physpages;
Hugh Dickins4266c972009-09-23 17:05:53 +010064unsigned long highest_memmap_pfn;
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -070065struct percpu_counter vm_committed_as;
Linus Torvalds1da177e2005-04-16 15:20:36 -070066int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
67int sysctl_overcommit_ratio = 50; /* default is 50% */
68int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
David Howellsfc4d5c22009-05-06 16:03:05 -070069int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070int heap_stack_gap = 0;
71
David Howells33e5d7692009-04-02 16:56:32 -070072atomic_long_t mmap_pages_allocated;
David Howells8feae132009-01-08 12:04:47 +000073
Linus Torvalds1da177e2005-04-16 15:20:36 -070074EXPORT_SYMBOL(mem_map);
Wu, Bryan6a04de62007-04-11 23:28:47 -070075EXPORT_SYMBOL(num_physpages);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
David Howells8feae132009-01-08 12:04:47 +000077/* list of mapped, potentially shareable regions */
78static struct kmem_cache *vm_region_jar;
79struct rb_root nommu_region_tree = RB_ROOT;
80DECLARE_RWSEM(nommu_region_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +040082const struct vm_operations_struct generic_file_vm_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070083};
84
85/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 * Return the total memory allocated for this pointer, not
87 * just what the caller asked for.
88 *
89 * Doesn't have to be accurate, i.e. may have races.
90 */
91unsigned int kobjsize(const void *objp)
92{
93 struct page *page;
94
Michael Hennerich4016a132008-04-28 02:13:38 -070095 /*
96 * If the object we have should not have ksize performed on it,
97 * return size of 0
98 */
Paul Mundt5a1603b2008-06-12 16:29:55 +090099 if (!objp || !virt_addr_valid(objp))
Paul Mundt6cfd53f2008-06-05 22:46:08 -0700100 return 0;
101
102 page = virt_to_head_page(objp);
Paul Mundt6cfd53f2008-06-05 22:46:08 -0700103
104 /*
105 * If the allocator sets PageSlab, we know the pointer came from
106 * kmalloc().
107 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 if (PageSlab(page))
109 return ksize(objp);
110
Paul Mundt6cfd53f2008-06-05 22:46:08 -0700111 /*
Paul Mundtab2e83e2009-01-08 12:04:48 +0000112 * If it's not a compound page, see if we have a matching VMA
113 * region. This test is intentionally done in reverse order,
114 * so if there's no VMA, we still fall through and hand back
115 * PAGE_SIZE for 0-order pages.
116 */
117 if (!PageCompound(page)) {
118 struct vm_area_struct *vma;
119
120 vma = find_vma(current->mm, (unsigned long)objp);
121 if (vma)
122 return vma->vm_end - vma->vm_start;
123 }
124
125 /*
Paul Mundt6cfd53f2008-06-05 22:46:08 -0700126 * The ksize() function is only guaranteed to work for pointers
Paul Mundt5a1603b2008-06-12 16:29:55 +0900127 * returned by kmalloc(). So handle arbitrary pointers here.
Paul Mundt6cfd53f2008-06-05 22:46:08 -0700128 */
Paul Mundt5a1603b2008-06-12 16:29:55 +0900129 return PAGE_SIZE << compound_order(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
Nick Pigginb291f002008-10-18 20:26:44 -0700132int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
Hugh Dickins4266c972009-09-23 17:05:53 +0100133 unsigned long start, int nr_pages, unsigned int foll_flags,
Peter Zijlstra9d737772009-06-25 11:58:55 +0200134 struct page **pages, struct vm_area_struct **vmas)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
Sonic Zhang910e46d2006-09-27 01:50:17 -0700136 struct vm_area_struct *vma;
David Howells7b4d5b82006-09-27 01:50:18 -0700137 unsigned long vm_flags;
138 int i;
139
140 /* calculate required read or write permissions.
Hugh Dickins58fa8792009-09-21 17:03:31 -0700141 * If FOLL_FORCE is set, we only require the "MAY" flags.
David Howells7b4d5b82006-09-27 01:50:18 -0700142 */
Hugh Dickins58fa8792009-09-21 17:03:31 -0700143 vm_flags = (foll_flags & FOLL_WRITE) ?
144 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
145 vm_flags &= (foll_flags & FOLL_FORCE) ?
146 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
Peter Zijlstra9d737772009-06-25 11:58:55 +0200148 for (i = 0; i < nr_pages; i++) {
David Howells7561e8c2010-03-25 16:48:38 +0000149 vma = find_vma(mm, start);
David Howells7b4d5b82006-09-27 01:50:18 -0700150 if (!vma)
151 goto finish_or_fault;
152
153 /* protect what we can, including chardevs */
Hugh Dickins1c3aff12009-09-21 17:03:24 -0700154 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
155 !(vm_flags & vma->vm_flags))
David Howells7b4d5b82006-09-27 01:50:18 -0700156 goto finish_or_fault;
Sonic Zhang910e46d2006-09-27 01:50:17 -0700157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 if (pages) {
159 pages[i] = virt_to_page(start);
160 if (pages[i])
161 page_cache_get(pages[i]);
162 }
163 if (vmas)
Sonic Zhang910e46d2006-09-27 01:50:17 -0700164 vmas[i] = vma;
David Howellse1ee65d2010-03-25 16:48:44 +0000165 start = (start + PAGE_SIZE) & PAGE_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 }
David Howells7b4d5b82006-09-27 01:50:18 -0700167
168 return i;
169
170finish_or_fault:
171 return i ? : -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172}
Nick Pigginb291f002008-10-18 20:26:44 -0700173
Nick Pigginb291f002008-10-18 20:26:44 -0700174/*
175 * get a list of pages in an address range belonging to the specified process
176 * and indicate the VMA that covers each page
177 * - this is potentially dodgy as we may end incrementing the page count of a
178 * slab page or a secondary page from a compound page
179 * - don't permit access to VMAs that don't support it, such as I/O mappings
180 */
181int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
Peter Zijlstra9d737772009-06-25 11:58:55 +0200182 unsigned long start, int nr_pages, int write, int force,
Nick Pigginb291f002008-10-18 20:26:44 -0700183 struct page **pages, struct vm_area_struct **vmas)
184{
185 int flags = 0;
186
187 if (write)
Hugh Dickins58fa8792009-09-21 17:03:31 -0700188 flags |= FOLL_WRITE;
Nick Pigginb291f002008-10-18 20:26:44 -0700189 if (force)
Hugh Dickins58fa8792009-09-21 17:03:31 -0700190 flags |= FOLL_FORCE;
Nick Pigginb291f002008-10-18 20:26:44 -0700191
Peter Zijlstra9d737772009-06-25 11:58:55 +0200192 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
Nick Pigginb291f002008-10-18 20:26:44 -0700193}
Greg Ungerer66aa2b42005-09-12 11:18:10 +1000194EXPORT_SYMBOL(get_user_pages);
195
Paul Mundtdfc2f912009-06-26 04:31:57 +0900196/**
197 * follow_pfn - look up PFN at a user virtual address
198 * @vma: memory mapping
199 * @address: user virtual address
200 * @pfn: location to store found PFN
201 *
202 * Only IO mappings and raw PFN mappings are allowed.
203 *
204 * Returns zero and the pfn at @pfn on success, -ve otherwise.
205 */
206int follow_pfn(struct vm_area_struct *vma, unsigned long address,
207 unsigned long *pfn)
208{
209 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
210 return -EINVAL;
211
212 *pfn = address >> PAGE_SHIFT;
213 return 0;
214}
215EXPORT_SYMBOL(follow_pfn);
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217DEFINE_RWLOCK(vmlist_lock);
218struct vm_struct *vmlist;
219
Christoph Lameterb3bdda02008-02-04 22:28:32 -0800220void vfree(const void *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221{
222 kfree(addr);
223}
Paul Mundtb5073172007-07-21 04:37:25 -0700224EXPORT_SYMBOL(vfree);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
Al Virodd0fc662005-10-07 07:46:04 +0100226void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227{
228 /*
Robert P. J. Day85186092007-10-19 23:11:38 +0200229 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
230 * returns only a logical address.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 */
Nick Piggin84097512006-03-22 00:08:34 -0800232 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233}
Paul Mundtb5073172007-07-21 04:37:25 -0700234EXPORT_SYMBOL(__vmalloc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
Paul Mundtf905bc42008-02-04 22:29:59 -0800236void *vmalloc_user(unsigned long size)
237{
238 void *ret;
239
240 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
241 PAGE_KERNEL);
242 if (ret) {
243 struct vm_area_struct *vma;
244
245 down_write(&current->mm->mmap_sem);
246 vma = find_vma(current->mm, (unsigned long)ret);
247 if (vma)
248 vma->vm_flags |= VM_USERMAP;
249 up_write(&current->mm->mmap_sem);
250 }
251
252 return ret;
253}
254EXPORT_SYMBOL(vmalloc_user);
255
Christoph Lameterb3bdda02008-02-04 22:28:32 -0800256struct page *vmalloc_to_page(const void *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
258 return virt_to_page(addr);
259}
Paul Mundtb5073172007-07-21 04:37:25 -0700260EXPORT_SYMBOL(vmalloc_to_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
Christoph Lameterb3bdda02008-02-04 22:28:32 -0800262unsigned long vmalloc_to_pfn(const void *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263{
264 return page_to_pfn(virt_to_page(addr));
265}
Paul Mundtb5073172007-07-21 04:37:25 -0700266EXPORT_SYMBOL(vmalloc_to_pfn);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267
268long vread(char *buf, char *addr, unsigned long count)
269{
270 memcpy(buf, addr, count);
271 return count;
272}
273
274long vwrite(char *buf, char *addr, unsigned long count)
275{
276 /* Don't allow overflow */
277 if ((unsigned long) addr + count < count)
278 count = -(unsigned long) addr;
279
280 memcpy(addr, buf, count);
281 return(count);
282}
283
284/*
285 * vmalloc - allocate virtually continguos memory
286 *
287 * @size: allocation size
288 *
289 * Allocate enough pages to cover @size from the page level
290 * allocator and map them into continguos kernel virtual space.
291 *
Michael Opdenackerc1c88972006-10-03 23:21:02 +0200292 * For tight control over page level allocator and protection flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 * use __vmalloc() instead.
294 */
295void *vmalloc(unsigned long size)
296{
297 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
298}
Andrew Mortonf6138882006-02-28 16:59:18 -0800299EXPORT_SYMBOL(vmalloc);
300
301void *vmalloc_node(unsigned long size, int node)
302{
303 return vmalloc(size);
304}
305EXPORT_SYMBOL(vmalloc_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306
Paul Mundt1af446e2008-08-04 16:01:47 +0900307#ifndef PAGE_KERNEL_EXEC
308# define PAGE_KERNEL_EXEC PAGE_KERNEL
309#endif
310
311/**
312 * vmalloc_exec - allocate virtually contiguous, executable memory
313 * @size: allocation size
314 *
315 * Kernel-internal function to allocate enough pages to cover @size
316 * the page level allocator and map them into contiguous and
317 * executable kernel virtual space.
318 *
319 * For tight control over page level allocator and protection flags
320 * use __vmalloc() instead.
321 */
322
323void *vmalloc_exec(unsigned long size)
324{
325 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
326}
327
Paul Mundtb5073172007-07-21 04:37:25 -0700328/**
329 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 * @size: allocation size
331 *
332 * Allocate enough 32bit PA addressable pages to cover @size from the
333 * page level allocator and map them into continguos kernel virtual space.
334 */
335void *vmalloc_32(unsigned long size)
336{
337 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
338}
Paul Mundtb5073172007-07-21 04:37:25 -0700339EXPORT_SYMBOL(vmalloc_32);
340
341/**
342 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
343 * @size: allocation size
344 *
345 * The resulting memory area is 32bit addressable and zeroed so it can be
346 * mapped to userspace without leaking data.
Paul Mundtf905bc42008-02-04 22:29:59 -0800347 *
348 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
349 * remap_vmalloc_range() are permissible.
Paul Mundtb5073172007-07-21 04:37:25 -0700350 */
351void *vmalloc_32_user(unsigned long size)
352{
Paul Mundtf905bc42008-02-04 22:29:59 -0800353 /*
354 * We'll have to sort out the ZONE_DMA bits for 64-bit,
355 * but for now this can simply use vmalloc_user() directly.
356 */
357 return vmalloc_user(size);
Paul Mundtb5073172007-07-21 04:37:25 -0700358}
359EXPORT_SYMBOL(vmalloc_32_user);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360
361void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
362{
363 BUG();
364 return NULL;
365}
Paul Mundtb5073172007-07-21 04:37:25 -0700366EXPORT_SYMBOL(vmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
Christoph Lameterb3bdda02008-02-04 22:28:32 -0800368void vunmap(const void *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369{
370 BUG();
371}
Paul Mundtb5073172007-07-21 04:37:25 -0700372EXPORT_SYMBOL(vunmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373
Paul Mundteb6434d2009-01-21 17:45:47 +0900374void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
375{
376 BUG();
377 return NULL;
378}
379EXPORT_SYMBOL(vm_map_ram);
380
381void vm_unmap_ram(const void *mem, unsigned int count)
382{
383 BUG();
384}
385EXPORT_SYMBOL(vm_unmap_ram);
386
387void vm_unmap_aliases(void)
388{
389}
390EXPORT_SYMBOL_GPL(vm_unmap_aliases);
391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392/*
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -0700393 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
394 * have one.
395 */
396void __attribute__((weak)) vmalloc_sync_all(void)
397{
398}
399
Paul Mundtb5073172007-07-21 04:37:25 -0700400int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
401 struct page *page)
402{
403 return -EINVAL;
404}
405EXPORT_SYMBOL(vm_insert_page);
406
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -0700407/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 * sys_brk() for the most part doesn't need the global kernel
409 * lock, except when an application is doing something nasty
410 * like trying to un-brk an area that has already been mapped
411 * to a regular file. in this case, the unmapping will need
412 * to invoke file system routines that need the global lock.
413 */
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100414SYSCALL_DEFINE1(brk, unsigned long, brk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415{
416 struct mm_struct *mm = current->mm;
417
418 if (brk < mm->start_brk || brk > mm->context.end_brk)
419 return mm->brk;
420
421 if (mm->brk == brk)
422 return mm->brk;
423
424 /*
425 * Always allow shrinking brk
426 */
427 if (brk <= mm->brk) {
428 mm->brk = brk;
429 return brk;
430 }
431
432 /*
433 * Ok, looks good - let it rip.
434 */
Mike Frysingercfe79c02010-01-06 17:23:23 +0000435 flush_icache_range(mm->brk, brk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 return mm->brk = brk;
437}
438
David Howells8feae132009-01-08 12:04:47 +0000439/*
440 * initialise the VMA and region record slabs
441 */
442void __init mmap_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443{
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -0700444 int ret;
445
446 ret = percpu_counter_init(&vm_committed_as, 0);
447 VM_BUG_ON(ret);
David Howells33e5d7692009-04-02 16:56:32 -0700448 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
David Howells8feae132009-01-08 12:04:47 +0000449}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450
David Howells8feae132009-01-08 12:04:47 +0000451/*
452 * validate the region tree
453 * - the caller must hold the region lock
454 */
455#ifdef CONFIG_DEBUG_NOMMU_REGIONS
456static noinline void validate_nommu_regions(void)
457{
458 struct vm_region *region, *last;
459 struct rb_node *p, *lastp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460
David Howells8feae132009-01-08 12:04:47 +0000461 lastp = rb_first(&nommu_region_tree);
462 if (!lastp)
463 return;
464
465 last = rb_entry(lastp, struct vm_region, vm_rb);
David Howells33e5d7692009-04-02 16:56:32 -0700466 BUG_ON(unlikely(last->vm_end <= last->vm_start));
467 BUG_ON(unlikely(last->vm_top < last->vm_end));
David Howells8feae132009-01-08 12:04:47 +0000468
469 while ((p = rb_next(lastp))) {
470 region = rb_entry(p, struct vm_region, vm_rb);
471 last = rb_entry(lastp, struct vm_region, vm_rb);
472
David Howells33e5d7692009-04-02 16:56:32 -0700473 BUG_ON(unlikely(region->vm_end <= region->vm_start));
474 BUG_ON(unlikely(region->vm_top < region->vm_end));
475 BUG_ON(unlikely(region->vm_start < last->vm_top));
David Howells8feae132009-01-08 12:04:47 +0000476
477 lastp = p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 }
479}
David Howells8feae132009-01-08 12:04:47 +0000480#else
David Howells33e5d7692009-04-02 16:56:32 -0700481static void validate_nommu_regions(void)
482{
483}
David Howells8feae132009-01-08 12:04:47 +0000484#endif
485
486/*
487 * add a region into the global tree
488 */
489static void add_nommu_region(struct vm_region *region)
490{
491 struct vm_region *pregion;
492 struct rb_node **p, *parent;
493
494 validate_nommu_regions();
495
David Howells8feae132009-01-08 12:04:47 +0000496 parent = NULL;
497 p = &nommu_region_tree.rb_node;
498 while (*p) {
499 parent = *p;
500 pregion = rb_entry(parent, struct vm_region, vm_rb);
501 if (region->vm_start < pregion->vm_start)
502 p = &(*p)->rb_left;
503 else if (region->vm_start > pregion->vm_start)
504 p = &(*p)->rb_right;
505 else if (pregion == region)
506 return;
507 else
508 BUG();
509 }
510
511 rb_link_node(&region->vm_rb, parent, p);
512 rb_insert_color(&region->vm_rb, &nommu_region_tree);
513
514 validate_nommu_regions();
515}
516
517/*
518 * delete a region from the global tree
519 */
520static void delete_nommu_region(struct vm_region *region)
521{
522 BUG_ON(!nommu_region_tree.rb_node);
523
524 validate_nommu_regions();
525 rb_erase(&region->vm_rb, &nommu_region_tree);
526 validate_nommu_regions();
527}
528
529/*
530 * free a contiguous series of pages
531 */
532static void free_page_series(unsigned long from, unsigned long to)
533{
534 for (; from < to; from += PAGE_SIZE) {
535 struct page *page = virt_to_page(from);
536
537 kdebug("- free %lx", from);
David Howells33e5d7692009-04-02 16:56:32 -0700538 atomic_long_dec(&mmap_pages_allocated);
David Howells8feae132009-01-08 12:04:47 +0000539 if (page_count(page) != 1)
David Howells33e5d7692009-04-02 16:56:32 -0700540 kdebug("free page %p: refcount not one: %d",
541 page, page_count(page));
David Howells8feae132009-01-08 12:04:47 +0000542 put_page(page);
543 }
544}
545
546/*
547 * release a reference to a region
David Howells33e5d7692009-04-02 16:56:32 -0700548 * - the caller must hold the region semaphore for writing, which this releases
Paul Mundtdd8632a2009-01-08 12:04:47 +0000549 * - the region may not have been added to the tree yet, in which case vm_top
David Howells8feae132009-01-08 12:04:47 +0000550 * will equal vm_start
551 */
552static void __put_nommu_region(struct vm_region *region)
553 __releases(nommu_region_sem)
554{
David Howells1e2ae592010-01-15 17:01:33 -0800555 kenter("%p{%d}", region, region->vm_usage);
David Howells8feae132009-01-08 12:04:47 +0000556
557 BUG_ON(!nommu_region_tree.rb_node);
558
David Howells1e2ae592010-01-15 17:01:33 -0800559 if (--region->vm_usage == 0) {
Paul Mundtdd8632a2009-01-08 12:04:47 +0000560 if (region->vm_top > region->vm_start)
David Howells8feae132009-01-08 12:04:47 +0000561 delete_nommu_region(region);
562 up_write(&nommu_region_sem);
563
564 if (region->vm_file)
565 fput(region->vm_file);
566
567 /* IO memory and memory shared directly out of the pagecache
568 * from ramfs/tmpfs mustn't be released here */
569 if (region->vm_flags & VM_MAPPED_COPY) {
570 kdebug("free series");
Paul Mundtdd8632a2009-01-08 12:04:47 +0000571 free_page_series(region->vm_start, region->vm_top);
David Howells8feae132009-01-08 12:04:47 +0000572 }
573 kmem_cache_free(vm_region_jar, region);
574 } else {
575 up_write(&nommu_region_sem);
576 }
577}
578
579/*
580 * release a reference to a region
581 */
582static void put_nommu_region(struct vm_region *region)
583{
584 down_write(&nommu_region_sem);
585 __put_nommu_region(region);
586}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587
David Howells30340972006-09-27 01:50:20 -0700588/*
Bernd Schmidteb8cdec2009-09-21 17:03:57 -0700589 * update protection on a vma
590 */
591static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
592{
593#ifdef CONFIG_MPU
594 struct mm_struct *mm = vma->vm_mm;
595 long start = vma->vm_start & PAGE_MASK;
596 while (start < vma->vm_end) {
597 protect_page(mm, start, flags);
598 start += PAGE_SIZE;
599 }
600 update_protections(mm);
601#endif
602}
603
604/*
David Howells30340972006-09-27 01:50:20 -0700605 * add a VMA into a process's mm_struct in the appropriate place in the list
David Howells8feae132009-01-08 12:04:47 +0000606 * and tree and add to the address space's page tree also if not an anonymous
607 * page
David Howells30340972006-09-27 01:50:20 -0700608 * - should be called with mm->mmap_sem held writelocked
609 */
David Howells8feae132009-01-08 12:04:47 +0000610static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
David Howells30340972006-09-27 01:50:20 -0700611{
David Howells8feae132009-01-08 12:04:47 +0000612 struct vm_area_struct *pvma, **pp;
613 struct address_space *mapping;
614 struct rb_node **p, *parent;
David Howells30340972006-09-27 01:50:20 -0700615
David Howells8feae132009-01-08 12:04:47 +0000616 kenter(",%p", vma);
617
618 BUG_ON(!vma->vm_region);
619
620 mm->map_count++;
621 vma->vm_mm = mm;
622
Bernd Schmidteb8cdec2009-09-21 17:03:57 -0700623 protect_vma(vma, vma->vm_flags);
624
David Howells8feae132009-01-08 12:04:47 +0000625 /* add the VMA to the mapping */
626 if (vma->vm_file) {
627 mapping = vma->vm_file->f_mapping;
628
629 flush_dcache_mmap_lock(mapping);
630 vma_prio_tree_insert(vma, &mapping->i_mmap);
631 flush_dcache_mmap_unlock(mapping);
632 }
633
634 /* add the VMA to the tree */
635 parent = NULL;
636 p = &mm->mm_rb.rb_node;
637 while (*p) {
638 parent = *p;
639 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
640
641 /* sort by: start addr, end addr, VMA struct addr in that order
642 * (the latter is necessary as we may get identical VMAs) */
643 if (vma->vm_start < pvma->vm_start)
644 p = &(*p)->rb_left;
645 else if (vma->vm_start > pvma->vm_start)
646 p = &(*p)->rb_right;
647 else if (vma->vm_end < pvma->vm_end)
648 p = &(*p)->rb_left;
649 else if (vma->vm_end > pvma->vm_end)
650 p = &(*p)->rb_right;
651 else if (vma < pvma)
652 p = &(*p)->rb_left;
653 else if (vma > pvma)
654 p = &(*p)->rb_right;
655 else
656 BUG();
657 }
658
659 rb_link_node(&vma->vm_rb, parent, p);
660 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
661
662 /* add VMA to the VMA list also */
663 for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
664 if (pvma->vm_start > vma->vm_start)
David Howells30340972006-09-27 01:50:20 -0700665 break;
David Howells8feae132009-01-08 12:04:47 +0000666 if (pvma->vm_start < vma->vm_start)
667 continue;
668 if (pvma->vm_end < vma->vm_end)
669 break;
670 }
David Howells30340972006-09-27 01:50:20 -0700671
David Howells8feae132009-01-08 12:04:47 +0000672 vma->vm_next = *pp;
673 *pp = vma;
674}
675
676/*
677 * delete a VMA from its owning mm_struct and address space
678 */
679static void delete_vma_from_mm(struct vm_area_struct *vma)
680{
681 struct vm_area_struct **pp;
682 struct address_space *mapping;
683 struct mm_struct *mm = vma->vm_mm;
684
685 kenter("%p", vma);
686
Bernd Schmidteb8cdec2009-09-21 17:03:57 -0700687 protect_vma(vma, 0);
688
David Howells8feae132009-01-08 12:04:47 +0000689 mm->map_count--;
690 if (mm->mmap_cache == vma)
691 mm->mmap_cache = NULL;
692
693 /* remove the VMA from the mapping */
694 if (vma->vm_file) {
695 mapping = vma->vm_file->f_mapping;
696
697 flush_dcache_mmap_lock(mapping);
698 vma_prio_tree_remove(vma, &mapping->i_mmap);
699 flush_dcache_mmap_unlock(mapping);
700 }
701
702 /* remove from the MM's tree and list */
703 rb_erase(&vma->vm_rb, &mm->mm_rb);
704 for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
705 if (*pp == vma) {
706 *pp = vma->vm_next;
707 break;
708 }
709 }
710
711 vma->vm_mm = NULL;
712}
713
714/*
715 * destroy a VMA record
716 */
717static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
718{
719 kenter("%p", vma);
720 if (vma->vm_ops && vma->vm_ops->close)
721 vma->vm_ops->close(vma);
722 if (vma->vm_file) {
723 fput(vma->vm_file);
724 if (vma->vm_flags & VM_EXECUTABLE)
725 removed_exe_file_vma(mm);
726 }
727 put_nommu_region(vma->vm_region);
728 kmem_cache_free(vm_area_cachep, vma);
David Howells30340972006-09-27 01:50:20 -0700729}
730
731/*
732 * look up the first VMA in which addr resides, NULL if none
733 * - should be called with mm->mmap_sem at least held readlocked
734 */
735struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
736{
David Howells8feae132009-01-08 12:04:47 +0000737 struct vm_area_struct *vma;
738 struct rb_node *n = mm->mm_rb.rb_node;
David Howells30340972006-09-27 01:50:20 -0700739
David Howells8feae132009-01-08 12:04:47 +0000740 /* check the cache first */
741 vma = mm->mmap_cache;
742 if (vma && vma->vm_start <= addr && vma->vm_end > addr)
743 return vma;
744
745 /* trawl the tree (there may be multiple mappings in which addr
746 * resides) */
747 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
748 vma = rb_entry(n, struct vm_area_struct, vm_rb);
749 if (vma->vm_start > addr)
750 return NULL;
751 if (vma->vm_end > addr) {
752 mm->mmap_cache = vma;
753 return vma;
754 }
David Howells30340972006-09-27 01:50:20 -0700755 }
756
David Howells30340972006-09-27 01:50:20 -0700757 return NULL;
758}
759EXPORT_SYMBOL(find_vma);
760
761/*
David Howells930e6522006-09-27 01:50:22 -0700762 * find a VMA
763 * - we don't extend stack VMAs under NOMMU conditions
764 */
765struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
766{
David Howells7561e8c2010-03-25 16:48:38 +0000767 return find_vma(mm, addr);
David Howells930e6522006-09-27 01:50:22 -0700768}
769
David Howells8feae132009-01-08 12:04:47 +0000770/*
771 * expand a stack to a given address
772 * - not supported under NOMMU conditions
773 */
Greg Ungerer57c8f632007-07-15 23:38:28 -0700774int expand_stack(struct vm_area_struct *vma, unsigned long address)
775{
776 return -ENOMEM;
777}
778
David Howells930e6522006-09-27 01:50:22 -0700779/*
David Howells6fa5f802006-09-27 01:50:21 -0700780 * look up the first VMA exactly that exactly matches addr
781 * - should be called with mm->mmap_sem at least held readlocked
782 */
David Howells8feae132009-01-08 12:04:47 +0000783static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
784 unsigned long addr,
785 unsigned long len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786{
787 struct vm_area_struct *vma;
David Howells8feae132009-01-08 12:04:47 +0000788 struct rb_node *n = mm->mm_rb.rb_node;
789 unsigned long end = addr + len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
David Howells8feae132009-01-08 12:04:47 +0000791 /* check the cache first */
792 vma = mm->mmap_cache;
793 if (vma && vma->vm_start == addr && vma->vm_end == end)
794 return vma;
795
796 /* trawl the tree (there may be multiple mappings in which addr
797 * resides) */
798 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 vma = rb_entry(n, struct vm_area_struct, vm_rb);
David Howells8feae132009-01-08 12:04:47 +0000800 if (vma->vm_start < addr)
801 continue;
802 if (vma->vm_start > addr)
803 return NULL;
804 if (vma->vm_end == end) {
805 mm->mmap_cache = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 return vma;
David Howells8feae132009-01-08 12:04:47 +0000807 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 }
809
810 return NULL;
811}
812
David Howells30340972006-09-27 01:50:20 -0700813/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 * determine whether a mapping should be permitted and, if so, what sort of
815 * mapping we're capable of supporting
816 */
817static int validate_mmap_request(struct file *file,
818 unsigned long addr,
819 unsigned long len,
820 unsigned long prot,
821 unsigned long flags,
822 unsigned long pgoff,
823 unsigned long *_capabilities)
824{
David Howells8feae132009-01-08 12:04:47 +0000825 unsigned long capabilities, rlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 unsigned long reqprot = prot;
827 int ret;
828
829 /* do the simple checks first */
David Howells06aab5a2009-09-24 12:33:48 +0100830 if (flags & MAP_FIXED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 printk(KERN_DEBUG
832 "%d: Can't do fixed-address/overlay mmap of RAM\n",
833 current->pid);
834 return -EINVAL;
835 }
836
837 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
838 (flags & MAP_TYPE) != MAP_SHARED)
839 return -EINVAL;
840
Mike Frysingerf81cff02006-12-06 12:02:59 +1000841 if (!len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 return -EINVAL;
843
Mike Frysingerf81cff02006-12-06 12:02:59 +1000844 /* Careful about overflows.. */
David Howells8feae132009-01-08 12:04:47 +0000845 rlen = PAGE_ALIGN(len);
846 if (!rlen || rlen > TASK_SIZE)
Mike Frysingerf81cff02006-12-06 12:02:59 +1000847 return -ENOMEM;
848
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 /* offset overflow? */
David Howells8feae132009-01-08 12:04:47 +0000850 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
Mike Frysingerf81cff02006-12-06 12:02:59 +1000851 return -EOVERFLOW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852
853 if (file) {
854 /* validate file mapping requests */
855 struct address_space *mapping;
856
857 /* files must support mmap */
858 if (!file->f_op || !file->f_op->mmap)
859 return -ENODEV;
860
861 /* work out if what we've got could possibly be shared
862 * - we support chardevs that provide their own "memory"
863 * - we support files/blockdevs that are memory backed
864 */
865 mapping = file->f_mapping;
866 if (!mapping)
Josef Sipeke9536ae2006-12-08 02:37:21 -0800867 mapping = file->f_path.dentry->d_inode->i_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868
869 capabilities = 0;
870 if (mapping && mapping->backing_dev_info)
871 capabilities = mapping->backing_dev_info->capabilities;
872
873 if (!capabilities) {
874 /* no explicit capabilities set, so assume some
875 * defaults */
Josef Sipeke9536ae2006-12-08 02:37:21 -0800876 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 case S_IFREG:
878 case S_IFBLK:
879 capabilities = BDI_CAP_MAP_COPY;
880 break;
881
882 case S_IFCHR:
883 capabilities =
884 BDI_CAP_MAP_DIRECT |
885 BDI_CAP_READ_MAP |
886 BDI_CAP_WRITE_MAP;
887 break;
888
889 default:
890 return -EINVAL;
891 }
892 }
893
894 /* eliminate any capabilities that we can't support on this
895 * device */
896 if (!file->f_op->get_unmapped_area)
897 capabilities &= ~BDI_CAP_MAP_DIRECT;
898 if (!file->f_op->read)
899 capabilities &= ~BDI_CAP_MAP_COPY;
900
Graff Yang28d7a6a2009-08-18 14:11:17 -0700901 /* The file shall have been opened with read permission. */
902 if (!(file->f_mode & FMODE_READ))
903 return -EACCES;
904
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 if (flags & MAP_SHARED) {
906 /* do checks for writing, appending and locking */
907 if ((prot & PROT_WRITE) &&
908 !(file->f_mode & FMODE_WRITE))
909 return -EACCES;
910
Josef Sipeke9536ae2006-12-08 02:37:21 -0800911 if (IS_APPEND(file->f_path.dentry->d_inode) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 (file->f_mode & FMODE_WRITE))
913 return -EACCES;
914
Josef Sipeke9536ae2006-12-08 02:37:21 -0800915 if (locks_verify_locked(file->f_path.dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 return -EAGAIN;
917
918 if (!(capabilities & BDI_CAP_MAP_DIRECT))
919 return -ENODEV;
920
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 /* we mustn't privatise shared mappings */
922 capabilities &= ~BDI_CAP_MAP_COPY;
923 }
924 else {
925 /* we're going to read the file into private memory we
926 * allocate */
927 if (!(capabilities & BDI_CAP_MAP_COPY))
928 return -ENODEV;
929
930 /* we don't permit a private writable mapping to be
931 * shared with the backing device */
932 if (prot & PROT_WRITE)
933 capabilities &= ~BDI_CAP_MAP_DIRECT;
934 }
935
Bernd Schmidt3c7b2042010-05-25 23:43:00 -0700936 if (capabilities & BDI_CAP_MAP_DIRECT) {
937 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
938 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
939 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
940 ) {
941 capabilities &= ~BDI_CAP_MAP_DIRECT;
942 if (flags & MAP_SHARED) {
943 printk(KERN_WARNING
944 "MAP_SHARED not completely supported on !MMU\n");
945 return -EINVAL;
946 }
947 }
948 }
949
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 /* handle executable mappings and implied executable
951 * mappings */
Josef Sipeke9536ae2006-12-08 02:37:21 -0800952 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 if (prot & PROT_EXEC)
954 return -EPERM;
955 }
956 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
957 /* handle implication of PROT_EXEC by PROT_READ */
958 if (current->personality & READ_IMPLIES_EXEC) {
959 if (capabilities & BDI_CAP_EXEC_MAP)
960 prot |= PROT_EXEC;
961 }
962 }
963 else if ((prot & PROT_READ) &&
964 (prot & PROT_EXEC) &&
965 !(capabilities & BDI_CAP_EXEC_MAP)
966 ) {
967 /* backing file is not executable, try to copy */
968 capabilities &= ~BDI_CAP_MAP_DIRECT;
969 }
970 }
971 else {
972 /* anonymous mappings are always memory backed and can be
973 * privately mapped
974 */
975 capabilities = BDI_CAP_MAP_COPY;
976
977 /* handle PROT_EXEC implication by PROT_READ */
978 if ((prot & PROT_READ) &&
979 (current->personality & READ_IMPLIES_EXEC))
980 prot |= PROT_EXEC;
981 }
982
983 /* allow the security API to have its say */
Eric Parised032182007-06-28 15:55:21 -0400984 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 if (ret < 0)
986 return ret;
987
988 /* looks okay */
989 *_capabilities = capabilities;
990 return 0;
991}
992
993/*
994 * we've determined that we can make the mapping, now translate what we
995 * now know into VMA flags
996 */
997static unsigned long determine_vm_flags(struct file *file,
998 unsigned long prot,
999 unsigned long flags,
1000 unsigned long capabilities)
1001{
1002 unsigned long vm_flags;
1003
1004 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 /* vm_flags |= mm->def_flags; */
1006
1007 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1008 /* attempt to share read-only copies of mapped file chunks */
Bernd Schmidt3c7b2042010-05-25 23:43:00 -07001009 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 if (file && !(prot & PROT_WRITE))
1011 vm_flags |= VM_MAYSHARE;
Bernd Schmidt3c7b2042010-05-25 23:43:00 -07001012 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 /* overlay a shareable mapping on the backing device or inode
1014 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1015 * romfs/cramfs */
Bernd Schmidt3c7b2042010-05-25 23:43:00 -07001016 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 if (flags & MAP_SHARED)
Bernd Schmidt3c7b2042010-05-25 23:43:00 -07001018 vm_flags |= VM_SHARED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 }
1020
1021 /* refuse to let anyone share private mappings with this process if
1022 * it's being traced - otherwise breakpoints set in it may interfere
1023 * with another untraced process
1024 */
Roland McGrathfa8e26c2008-07-25 19:45:50 -07001025 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 vm_flags &= ~VM_MAYSHARE;
1027
1028 return vm_flags;
1029}
1030
1031/*
David Howells8feae132009-01-08 12:04:47 +00001032 * set up a shared mapping on a file (the driver or filesystem provides and
1033 * pins the storage)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 */
David Howells8feae132009-01-08 12:04:47 +00001035static int do_mmap_shared_file(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036{
1037 int ret;
1038
1039 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
Paul Mundtdd8632a2009-01-08 12:04:47 +00001040 if (ret == 0) {
1041 vma->vm_region->vm_top = vma->vm_region->vm_end;
David Howells645d83c2009-09-24 15:13:10 +01001042 return 0;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001043 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 if (ret != -ENOSYS)
1045 return ret;
1046
David Howells3fa30462010-03-23 13:35:21 -07001047 /* getting -ENOSYS indicates that direct mmap isn't possible (as
1048 * opposed to tried but failed) so we can only give a suitable error as
1049 * it's not possible to make a private copy if MAP_SHARED was given */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 return -ENODEV;
1051}
1052
1053/*
1054 * set up a private mapping or an anonymous shared mapping
1055 */
David Howells8feae132009-01-08 12:04:47 +00001056static int do_mmap_private(struct vm_area_struct *vma,
1057 struct vm_region *region,
David Howells645d83c2009-09-24 15:13:10 +01001058 unsigned long len,
1059 unsigned long capabilities)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060{
David Howells8feae132009-01-08 12:04:47 +00001061 struct page *pages;
1062 unsigned long total, point, n, rlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 void *base;
David Howells8feae132009-01-08 12:04:47 +00001064 int ret, order;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065
1066 /* invoke the file's mapping function so that it can keep track of
1067 * shared mappings on devices or memory
1068 * - VM_MAYSHARE will be set if it may attempt to share
1069 */
David Howells645d83c2009-09-24 15:13:10 +01001070 if (capabilities & BDI_CAP_MAP_DIRECT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
Paul Mundtdd8632a2009-01-08 12:04:47 +00001072 if (ret == 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 /* shouldn't return success if we're not sharing */
Paul Mundtdd8632a2009-01-08 12:04:47 +00001074 BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1075 vma->vm_region->vm_top = vma->vm_region->vm_end;
David Howells645d83c2009-09-24 15:13:10 +01001076 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 }
Paul Mundtdd8632a2009-01-08 12:04:47 +00001078 if (ret != -ENOSYS)
1079 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080
1081 /* getting an ENOSYS error indicates that direct mmap isn't
1082 * possible (as opposed to tried but failed) so we'll try to
1083 * make a private copy of the data and map that instead */
1084 }
1085
David Howells8feae132009-01-08 12:04:47 +00001086 rlen = PAGE_ALIGN(len);
1087
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 /* allocate some memory to hold the mapping
1089 * - note that this may not return a page-aligned address if the object
1090 * we're allocating is smaller than a page
1091 */
David Howells8feae132009-01-08 12:04:47 +00001092 order = get_order(rlen);
1093 kdebug("alloc order %d for %lx", order, len);
1094
1095 pages = alloc_pages(GFP_KERNEL, order);
1096 if (!pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 goto enomem;
1098
David Howells8feae132009-01-08 12:04:47 +00001099 total = 1 << order;
David Howells33e5d7692009-04-02 16:56:32 -07001100 atomic_long_add(total, &mmap_pages_allocated);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101
David Howells8feae132009-01-08 12:04:47 +00001102 point = rlen >> PAGE_SHIFT;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001103
1104 /* we allocated a power-of-2 sized page set, so we may want to trim off
1105 * the excess */
1106 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1107 while (total > point) {
1108 order = ilog2(total - point);
1109 n = 1 << order;
1110 kdebug("shave %lu/%lu @%lu", n, total - point, total);
David Howells33e5d7692009-04-02 16:56:32 -07001111 atomic_long_sub(n, &mmap_pages_allocated);
Paul Mundtdd8632a2009-01-08 12:04:47 +00001112 total -= n;
1113 set_page_refcounted(pages + total);
1114 __free_pages(pages + total, order);
1115 }
David Howells8feae132009-01-08 12:04:47 +00001116 }
1117
David Howells8feae132009-01-08 12:04:47 +00001118 for (point = 1; point < total; point++)
1119 set_page_refcounted(&pages[point]);
1120
1121 base = page_address(pages);
1122 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1123 region->vm_start = (unsigned long) base;
1124 region->vm_end = region->vm_start + rlen;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001125 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
David Howells8feae132009-01-08 12:04:47 +00001126
1127 vma->vm_start = region->vm_start;
1128 vma->vm_end = region->vm_start + len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129
1130 if (vma->vm_file) {
1131 /* read the contents of a file into the copy */
1132 mm_segment_t old_fs;
1133 loff_t fpos;
1134
1135 fpos = vma->vm_pgoff;
1136 fpos <<= PAGE_SHIFT;
1137
1138 old_fs = get_fs();
1139 set_fs(KERNEL_DS);
David Howells8feae132009-01-08 12:04:47 +00001140 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 set_fs(old_fs);
1142
1143 if (ret < 0)
1144 goto error_free;
1145
1146 /* clear the last little bit */
David Howells8feae132009-01-08 12:04:47 +00001147 if (ret < rlen)
1148 memset(base + ret, 0, rlen - ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150 }
1151
1152 return 0;
1153
1154error_free:
David Howells8feae132009-01-08 12:04:47 +00001155 free_page_series(region->vm_start, region->vm_end);
1156 region->vm_start = vma->vm_start = 0;
1157 region->vm_end = vma->vm_end = 0;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001158 region->vm_top = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 return ret;
1160
1161enomem:
Greg Ungerer05ae6fa2009-01-13 17:30:22 +10001162 printk("Allocation of length %lu from process %d (%s) failed\n",
1163 len, current->pid, current->comm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 show_free_areas();
1165 return -ENOMEM;
1166}
1167
1168/*
1169 * handle mapping creation for uClinux
1170 */
1171unsigned long do_mmap_pgoff(struct file *file,
1172 unsigned long addr,
1173 unsigned long len,
1174 unsigned long prot,
1175 unsigned long flags,
1176 unsigned long pgoff)
1177{
David Howells8feae132009-01-08 12:04:47 +00001178 struct vm_area_struct *vma;
1179 struct vm_region *region;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 struct rb_node *rb;
David Howells8feae132009-01-08 12:04:47 +00001181 unsigned long capabilities, vm_flags, result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182 int ret;
1183
David Howells8feae132009-01-08 12:04:47 +00001184 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1185
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 /* decide whether we should attempt the mapping, and if so what sort of
1187 * mapping */
1188 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1189 &capabilities);
David Howells8feae132009-01-08 12:04:47 +00001190 if (ret < 0) {
1191 kleave(" = %d [val]", ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 return ret;
David Howells8feae132009-01-08 12:04:47 +00001193 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194
David Howells06aab5a2009-09-24 12:33:48 +01001195 /* we ignore the address hint */
1196 addr = 0;
1197
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 /* we've determined that we can make the mapping, now translate what we
1199 * now know into VMA flags */
1200 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1201
David Howells8feae132009-01-08 12:04:47 +00001202 /* we're going to need to record the mapping */
1203 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1204 if (!region)
1205 goto error_getting_region;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
David Howells8feae132009-01-08 12:04:47 +00001207 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1208 if (!vma)
1209 goto error_getting_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210
David Howells1e2ae592010-01-15 17:01:33 -08001211 region->vm_usage = 1;
David Howells8feae132009-01-08 12:04:47 +00001212 region->vm_flags = vm_flags;
1213 region->vm_pgoff = pgoff;
1214
Rik van Riel5beb4932010-03-05 13:42:07 -08001215 INIT_LIST_HEAD(&vma->anon_vma_chain);
David Howells8feae132009-01-08 12:04:47 +00001216 vma->vm_flags = vm_flags;
1217 vma->vm_pgoff = pgoff;
1218
1219 if (file) {
1220 region->vm_file = file;
1221 get_file(file);
1222 vma->vm_file = file;
1223 get_file(file);
1224 if (vm_flags & VM_EXECUTABLE) {
1225 added_exe_file_vma(current->mm);
1226 vma->vm_mm = current->mm;
1227 }
1228 }
1229
1230 down_write(&nommu_region_sem);
1231
1232 /* if we want to share, we need to check for regions created by other
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 * mmap() calls that overlap with our proposed mapping
David Howells8feae132009-01-08 12:04:47 +00001234 * - we can only share with a superset match on most regular files
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 * - shared mappings on character devices and memory backed files are
1236 * permitted to overlap inexactly as far as we are concerned for in
1237 * these cases, sharing is handled in the driver or filesystem rather
1238 * than here
1239 */
1240 if (vm_flags & VM_MAYSHARE) {
David Howells8feae132009-01-08 12:04:47 +00001241 struct vm_region *pregion;
1242 unsigned long pglen, rpglen, pgend, rpgend, start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243
David Howells8feae132009-01-08 12:04:47 +00001244 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1245 pgend = pgoff + pglen;
David Howells165b2392007-03-22 00:11:24 -08001246
David Howells8feae132009-01-08 12:04:47 +00001247 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1248 pregion = rb_entry(rb, struct vm_region, vm_rb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
David Howells8feae132009-01-08 12:04:47 +00001250 if (!(pregion->vm_flags & VM_MAYSHARE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 continue;
1252
1253 /* search for overlapping mappings on the same file */
David Howells8feae132009-01-08 12:04:47 +00001254 if (pregion->vm_file->f_path.dentry->d_inode !=
1255 file->f_path.dentry->d_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 continue;
1257
David Howells8feae132009-01-08 12:04:47 +00001258 if (pregion->vm_pgoff >= pgend)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259 continue;
1260
David Howells8feae132009-01-08 12:04:47 +00001261 rpglen = pregion->vm_end - pregion->vm_start;
1262 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1263 rpgend = pregion->vm_pgoff + rpglen;
1264 if (pgoff >= rpgend)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 continue;
1266
David Howells8feae132009-01-08 12:04:47 +00001267 /* handle inexactly overlapping matches between
1268 * mappings */
1269 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1270 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1271 /* new mapping is not a subset of the region */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1273 goto sharing_violation;
1274 continue;
1275 }
1276
David Howells8feae132009-01-08 12:04:47 +00001277 /* we've found a region we can share */
David Howells1e2ae592010-01-15 17:01:33 -08001278 pregion->vm_usage++;
David Howells8feae132009-01-08 12:04:47 +00001279 vma->vm_region = pregion;
1280 start = pregion->vm_start;
1281 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1282 vma->vm_start = start;
1283 vma->vm_end = start + len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
David Howells8feae132009-01-08 12:04:47 +00001285 if (pregion->vm_flags & VM_MAPPED_COPY) {
1286 kdebug("share copy");
1287 vma->vm_flags |= VM_MAPPED_COPY;
1288 } else {
1289 kdebug("share mmap");
1290 ret = do_mmap_shared_file(vma);
1291 if (ret < 0) {
1292 vma->vm_region = NULL;
1293 vma->vm_start = 0;
1294 vma->vm_end = 0;
David Howells1e2ae592010-01-15 17:01:33 -08001295 pregion->vm_usage--;
David Howells8feae132009-01-08 12:04:47 +00001296 pregion = NULL;
1297 goto error_just_free;
1298 }
1299 }
1300 fput(region->vm_file);
1301 kmem_cache_free(vm_region_jar, region);
1302 region = pregion;
1303 result = start;
1304 goto share;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305 }
1306
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 /* obtain the address at which to make a shared mapping
1308 * - this is the hook for quasi-memory character devices to
1309 * tell us the location of a shared mapping
1310 */
David Howells645d83c2009-09-24 15:13:10 +01001311 if (capabilities & BDI_CAP_MAP_DIRECT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 addr = file->f_op->get_unmapped_area(file, addr, len,
1313 pgoff, flags);
1314 if (IS_ERR((void *) addr)) {
1315 ret = addr;
1316 if (ret != (unsigned long) -ENOSYS)
David Howells8feae132009-01-08 12:04:47 +00001317 goto error_just_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318
1319 /* the driver refused to tell us where to site
1320 * the mapping so we'll have to attempt to copy
1321 * it */
1322 ret = (unsigned long) -ENODEV;
1323 if (!(capabilities & BDI_CAP_MAP_COPY))
David Howells8feae132009-01-08 12:04:47 +00001324 goto error_just_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325
1326 capabilities &= ~BDI_CAP_MAP_DIRECT;
David Howells8feae132009-01-08 12:04:47 +00001327 } else {
1328 vma->vm_start = region->vm_start = addr;
1329 vma->vm_end = region->vm_end = addr + len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330 }
1331 }
1332 }
1333
David Howells8feae132009-01-08 12:04:47 +00001334 vma->vm_region = region;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335
David Howells645d83c2009-09-24 15:13:10 +01001336 /* set up the mapping
1337 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1338 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 if (file && vma->vm_flags & VM_SHARED)
David Howells8feae132009-01-08 12:04:47 +00001340 ret = do_mmap_shared_file(vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 else
David Howells645d83c2009-09-24 15:13:10 +01001342 ret = do_mmap_private(vma, region, len, capabilities);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 if (ret < 0)
David Howells645d83c2009-09-24 15:13:10 +01001344 goto error_just_free;
1345 add_nommu_region(region);
David Howells8feae132009-01-08 12:04:47 +00001346
Jie Zhangea637632009-12-14 18:00:02 -08001347 /* clear anonymous mappings that don't ask for uninitialized data */
1348 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1349 memset((void *)region->vm_start, 0,
1350 region->vm_end - region->vm_start);
1351
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 /* okay... we have a mapping; now we have to register it */
David Howells8feae132009-01-08 12:04:47 +00001353 result = vma->vm_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 current->mm->total_vm += len >> PAGE_SHIFT;
1356
David Howells8feae132009-01-08 12:04:47 +00001357share:
1358 add_vma_to_mm(current->mm, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359
Mike Frysingercfe79c02010-01-06 17:23:23 +00001360 /* we flush the region from the icache only when the first executable
1361 * mapping of it is made */
1362 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1363 flush_icache_range(region->vm_start, region->vm_end);
1364 region->vm_icache_flushed = true;
1365 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Mike Frysingercfe79c02010-01-06 17:23:23 +00001367 up_write(&nommu_region_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
David Howells8feae132009-01-08 12:04:47 +00001369 kleave(" = %lx", result);
1370 return result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371
David Howells8feae132009-01-08 12:04:47 +00001372error_just_free:
1373 up_write(&nommu_region_sem);
1374error:
David Howells89a86402009-10-30 13:13:26 +00001375 if (region->vm_file)
1376 fput(region->vm_file);
David Howells8feae132009-01-08 12:04:47 +00001377 kmem_cache_free(vm_region_jar, region);
David Howells89a86402009-10-30 13:13:26 +00001378 if (vma->vm_file)
1379 fput(vma->vm_file);
David Howells8feae132009-01-08 12:04:47 +00001380 if (vma->vm_flags & VM_EXECUTABLE)
1381 removed_exe_file_vma(vma->vm_mm);
1382 kmem_cache_free(vm_area_cachep, vma);
1383 kleave(" = %d", ret);
1384 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
David Howells8feae132009-01-08 12:04:47 +00001386sharing_violation:
1387 up_write(&nommu_region_sem);
1388 printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1389 ret = -EINVAL;
1390 goto error;
1391
1392error_getting_vma:
1393 kmem_cache_free(vm_region_jar, region);
1394 printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1395 " from process %d failed\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 len, current->pid);
1397 show_free_areas();
1398 return -ENOMEM;
1399
David Howells8feae132009-01-08 12:04:47 +00001400error_getting_region:
1401 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1402 " from process %d failed\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 len, current->pid);
1404 show_free_areas();
1405 return -ENOMEM;
1406}
Paul Mundtb5073172007-07-21 04:37:25 -07001407EXPORT_SYMBOL(do_mmap_pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408
Hugh Dickins66f0dc42009-12-30 20:17:34 +00001409SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1410 unsigned long, prot, unsigned long, flags,
1411 unsigned long, fd, unsigned long, pgoff)
1412{
1413 struct file *file = NULL;
1414 unsigned long retval = -EBADF;
1415
1416 if (!(flags & MAP_ANONYMOUS)) {
1417 file = fget(fd);
1418 if (!file)
1419 goto out;
1420 }
1421
1422 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1423
1424 down_write(&current->mm->mmap_sem);
1425 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1426 up_write(&current->mm->mmap_sem);
1427
1428 if (file)
1429 fput(file);
1430out:
1431 return retval;
1432}
1433
Christoph Hellwiga4679372010-03-10 15:21:15 -08001434#ifdef __ARCH_WANT_SYS_OLD_MMAP
1435struct mmap_arg_struct {
1436 unsigned long addr;
1437 unsigned long len;
1438 unsigned long prot;
1439 unsigned long flags;
1440 unsigned long fd;
1441 unsigned long offset;
1442};
1443
1444SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1445{
1446 struct mmap_arg_struct a;
1447
1448 if (copy_from_user(&a, arg, sizeof(a)))
1449 return -EFAULT;
1450 if (a.offset & ~PAGE_MASK)
1451 return -EINVAL;
1452
1453 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1454 a.offset >> PAGE_SHIFT);
1455}
1456#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458/*
David Howells8feae132009-01-08 12:04:47 +00001459 * split a vma into two pieces at address 'addr', a new vma is allocated either
1460 * for the first part or the tail.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461 */
David Howells8feae132009-01-08 12:04:47 +00001462int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1463 unsigned long addr, int new_below)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464{
David Howells8feae132009-01-08 12:04:47 +00001465 struct vm_area_struct *new;
1466 struct vm_region *region;
1467 unsigned long npages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468
David Howells8feae132009-01-08 12:04:47 +00001469 kenter("");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470
David Howells779c1022010-01-15 17:01:34 -08001471 /* we're only permitted to split anonymous regions (these should have
1472 * only a single usage on the region) */
1473 if (vma->vm_file)
David Howells8feae132009-01-08 12:04:47 +00001474 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475
David Howells8feae132009-01-08 12:04:47 +00001476 if (mm->map_count >= sysctl_max_map_count)
1477 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478
David Howells8feae132009-01-08 12:04:47 +00001479 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1480 if (!region)
1481 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482
David Howells8feae132009-01-08 12:04:47 +00001483 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1484 if (!new) {
1485 kmem_cache_free(vm_region_jar, region);
1486 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 }
David Howells8feae132009-01-08 12:04:47 +00001488
1489 /* most fields are the same, copy all, and then fixup */
1490 *new = *vma;
1491 *region = *vma->vm_region;
1492 new->vm_region = region;
1493
1494 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1495
1496 if (new_below) {
Paul Mundtdd8632a2009-01-08 12:04:47 +00001497 region->vm_top = region->vm_end = new->vm_end = addr;
David Howells8feae132009-01-08 12:04:47 +00001498 } else {
1499 region->vm_start = new->vm_start = addr;
1500 region->vm_pgoff = new->vm_pgoff += npages;
1501 }
1502
1503 if (new->vm_ops && new->vm_ops->open)
1504 new->vm_ops->open(new);
1505
1506 delete_vma_from_mm(vma);
1507 down_write(&nommu_region_sem);
1508 delete_nommu_region(vma->vm_region);
1509 if (new_below) {
1510 vma->vm_region->vm_start = vma->vm_start = addr;
1511 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1512 } else {
1513 vma->vm_region->vm_end = vma->vm_end = addr;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001514 vma->vm_region->vm_top = addr;
David Howells8feae132009-01-08 12:04:47 +00001515 }
1516 add_nommu_region(vma->vm_region);
1517 add_nommu_region(new->vm_region);
1518 up_write(&nommu_region_sem);
1519 add_vma_to_mm(mm, vma);
1520 add_vma_to_mm(mm, new);
1521 return 0;
1522}
1523
1524/*
1525 * shrink a VMA by removing the specified chunk from either the beginning or
1526 * the end
1527 */
1528static int shrink_vma(struct mm_struct *mm,
1529 struct vm_area_struct *vma,
1530 unsigned long from, unsigned long to)
1531{
1532 struct vm_region *region;
1533
1534 kenter("");
1535
1536 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1537 * and list */
1538 delete_vma_from_mm(vma);
1539 if (from > vma->vm_start)
1540 vma->vm_end = from;
1541 else
1542 vma->vm_start = to;
1543 add_vma_to_mm(mm, vma);
1544
1545 /* cut the backing region down to size */
1546 region = vma->vm_region;
David Howells1e2ae592010-01-15 17:01:33 -08001547 BUG_ON(region->vm_usage != 1);
David Howells8feae132009-01-08 12:04:47 +00001548
1549 down_write(&nommu_region_sem);
1550 delete_nommu_region(region);
Paul Mundtdd8632a2009-01-08 12:04:47 +00001551 if (from > region->vm_start) {
1552 to = region->vm_top;
1553 region->vm_top = region->vm_end = from;
1554 } else {
David Howells8feae132009-01-08 12:04:47 +00001555 region->vm_start = to;
Paul Mundtdd8632a2009-01-08 12:04:47 +00001556 }
David Howells8feae132009-01-08 12:04:47 +00001557 add_nommu_region(region);
1558 up_write(&nommu_region_sem);
1559
1560 free_page_series(from, to);
1561 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562}
1563
David Howells30340972006-09-27 01:50:20 -07001564/*
1565 * release a mapping
David Howells8feae132009-01-08 12:04:47 +00001566 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1567 * VMA, though it need not cover the whole VMA
David Howells30340972006-09-27 01:50:20 -07001568 */
David Howells8feae132009-01-08 12:04:47 +00001569int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570{
David Howells8feae132009-01-08 12:04:47 +00001571 struct vm_area_struct *vma;
1572 struct rb_node *rb;
1573 unsigned long end = start + len;
1574 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575
David Howells8feae132009-01-08 12:04:47 +00001576 kenter(",%lx,%zx", start, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577
David Howells8feae132009-01-08 12:04:47 +00001578 if (len == 0)
1579 return -EINVAL;
1580
1581 /* find the first potentially overlapping VMA */
1582 vma = find_vma(mm, start);
1583 if (!vma) {
David Howells33e5d7692009-04-02 16:56:32 -07001584 static int limit = 0;
1585 if (limit < 5) {
1586 printk(KERN_WARNING
1587 "munmap of memory not mmapped by process %d"
1588 " (%s): 0x%lx-0x%lx\n",
1589 current->pid, current->comm,
1590 start, start + len - 1);
1591 limit++;
1592 }
David Howells8feae132009-01-08 12:04:47 +00001593 return -EINVAL;
David Howells30340972006-09-27 01:50:20 -07001594 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595
David Howells8feae132009-01-08 12:04:47 +00001596 /* we're allowed to split an anonymous VMA but not a file-backed one */
1597 if (vma->vm_file) {
1598 do {
1599 if (start > vma->vm_start) {
1600 kleave(" = -EINVAL [miss]");
1601 return -EINVAL;
1602 }
1603 if (end == vma->vm_end)
1604 goto erase_whole_vma;
1605 rb = rb_next(&vma->vm_rb);
1606 vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1607 } while (rb);
1608 kleave(" = -EINVAL [split file]");
1609 return -EINVAL;
1610 } else {
1611 /* the chunk must be a subset of the VMA found */
1612 if (start == vma->vm_start && end == vma->vm_end)
1613 goto erase_whole_vma;
1614 if (start < vma->vm_start || end > vma->vm_end) {
1615 kleave(" = -EINVAL [superset]");
1616 return -EINVAL;
1617 }
1618 if (start & ~PAGE_MASK) {
1619 kleave(" = -EINVAL [unaligned start]");
1620 return -EINVAL;
1621 }
1622 if (end != vma->vm_end && end & ~PAGE_MASK) {
1623 kleave(" = -EINVAL [unaligned split]");
1624 return -EINVAL;
1625 }
1626 if (start != vma->vm_start && end != vma->vm_end) {
1627 ret = split_vma(mm, vma, start, 1);
1628 if (ret < 0) {
1629 kleave(" = %d [split]", ret);
1630 return ret;
1631 }
1632 }
1633 return shrink_vma(mm, vma, start, end);
1634 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635
David Howells8feae132009-01-08 12:04:47 +00001636erase_whole_vma:
1637 delete_vma_from_mm(vma);
1638 delete_vma(mm, vma);
1639 kleave(" = 0");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 return 0;
1641}
Paul Mundtb5073172007-07-21 04:37:25 -07001642EXPORT_SYMBOL(do_munmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643
Heiko Carstens6a6160a2009-01-14 14:14:15 +01001644SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
David Howells30340972006-09-27 01:50:20 -07001645{
1646 int ret;
1647 struct mm_struct *mm = current->mm;
1648
1649 down_write(&mm->mmap_sem);
1650 ret = do_munmap(mm, addr, len);
1651 up_write(&mm->mmap_sem);
1652 return ret;
1653}
1654
1655/*
David Howells8feae132009-01-08 12:04:47 +00001656 * release all the mappings made in a process's VM space
David Howells30340972006-09-27 01:50:20 -07001657 */
David Howells8feae132009-01-08 12:04:47 +00001658void exit_mmap(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659{
David Howells8feae132009-01-08 12:04:47 +00001660 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661
David Howells8feae132009-01-08 12:04:47 +00001662 if (!mm)
1663 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664
David Howells8feae132009-01-08 12:04:47 +00001665 kenter("");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666
David Howells8feae132009-01-08 12:04:47 +00001667 mm->total_vm = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668
David Howells8feae132009-01-08 12:04:47 +00001669 while ((vma = mm->mmap)) {
1670 mm->mmap = vma->vm_next;
1671 delete_vma_from_mm(vma);
1672 delete_vma(mm, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 }
David Howells8feae132009-01-08 12:04:47 +00001674
1675 kleave("");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676}
1677
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678unsigned long do_brk(unsigned long addr, unsigned long len)
1679{
1680 return -ENOMEM;
1681}
1682
1683/*
David Howells6fa5f802006-09-27 01:50:21 -07001684 * expand (or shrink) an existing mapping, potentially moving it at the same
1685 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 *
David Howells6fa5f802006-09-27 01:50:21 -07001687 * under NOMMU conditions, we only permit changing a mapping's size, and only
David Howells8feae132009-01-08 12:04:47 +00001688 * as long as it stays within the region allocated by do_mmap_private() and the
1689 * block is not shareable
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 *
David Howells6fa5f802006-09-27 01:50:21 -07001691 * MREMAP_FIXED is not supported under NOMMU conditions
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 */
1693unsigned long do_mremap(unsigned long addr,
1694 unsigned long old_len, unsigned long new_len,
1695 unsigned long flags, unsigned long new_addr)
1696{
David Howells6fa5f802006-09-27 01:50:21 -07001697 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698
1699 /* insanity checks first */
David Howells8feae132009-01-08 12:04:47 +00001700 if (old_len == 0 || new_len == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 return (unsigned long) -EINVAL;
1702
David Howells8feae132009-01-08 12:04:47 +00001703 if (addr & ~PAGE_MASK)
1704 return -EINVAL;
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 if (flags & MREMAP_FIXED && new_addr != addr)
1707 return (unsigned long) -EINVAL;
1708
David Howells8feae132009-01-08 12:04:47 +00001709 vma = find_vma_exact(current->mm, addr, old_len);
David Howells6fa5f802006-09-27 01:50:21 -07001710 if (!vma)
1711 return (unsigned long) -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
David Howells6fa5f802006-09-27 01:50:21 -07001713 if (vma->vm_end != vma->vm_start + old_len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 return (unsigned long) -EFAULT;
1715
David Howells6fa5f802006-09-27 01:50:21 -07001716 if (vma->vm_flags & VM_MAYSHARE)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 return (unsigned long) -EPERM;
1718
David Howells8feae132009-01-08 12:04:47 +00001719 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 return (unsigned long) -ENOMEM;
1721
1722 /* all checks complete - do it */
David Howells6fa5f802006-09-27 01:50:21 -07001723 vma->vm_end = vma->vm_start + new_len;
David Howells6fa5f802006-09-27 01:50:21 -07001724 return vma->vm_start;
1725}
Paul Mundtb5073172007-07-21 04:37:25 -07001726EXPORT_SYMBOL(do_mremap);
David Howells6fa5f802006-09-27 01:50:21 -07001727
Heiko Carstens6a6160a2009-01-14 14:14:15 +01001728SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1729 unsigned long, new_len, unsigned long, flags,
1730 unsigned long, new_addr)
David Howells6fa5f802006-09-27 01:50:21 -07001731{
1732 unsigned long ret;
1733
1734 down_write(&current->mm->mmap_sem);
1735 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1736 up_write(&current->mm->mmap_sem);
1737 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738}
1739
Linus Torvalds6aab3412005-11-28 14:34:23 -08001740struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001741 unsigned int foll_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742{
1743 return NULL;
1744}
1745
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1747 unsigned long to, unsigned long size, pgprot_t prot)
1748{
Greg Ungerer66aa2b42005-09-12 11:18:10 +10001749 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1750 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751}
Luke Yang22c4af42006-07-14 00:24:09 -07001752EXPORT_SYMBOL(remap_pfn_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753
Paul Mundtf905bc42008-02-04 22:29:59 -08001754int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1755 unsigned long pgoff)
1756{
1757 unsigned int size = vma->vm_end - vma->vm_start;
1758
1759 if (!(vma->vm_flags & VM_USERMAP))
1760 return -EINVAL;
1761
1762 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1763 vma->vm_end = vma->vm_start + size;
1764
1765 return 0;
1766}
1767EXPORT_SYMBOL(remap_vmalloc_range);
1768
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1770{
1771}
1772
1773unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1774 unsigned long len, unsigned long pgoff, unsigned long flags)
1775{
1776 return -ENOMEM;
1777}
1778
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001779void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780{
1781}
1782
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783void unmap_mapping_range(struct address_space *mapping,
1784 loff_t const holebegin, loff_t const holelen,
1785 int even_cows)
1786{
1787}
Luke Yang22c4af42006-07-14 00:24:09 -07001788EXPORT_SYMBOL(unmap_mapping_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789
1790/*
1791 * Check that a process has enough memory to allocate a new virtual
1792 * mapping. 0 means there is enough memory for the allocation to
1793 * succeed and -ENOMEM implies there is not.
1794 *
1795 * We currently support three overcommit policies, which are set via the
1796 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1797 *
1798 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1799 * Additional code 2002 Jul 20 by Robert Love.
1800 *
1801 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1802 *
1803 * Note this is a helper function intended to be used by LSMs which
1804 * wish to use this logic.
1805 */
Alan Cox34b4e4a2007-08-22 14:01:28 -07001806int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807{
1808 unsigned long free, allowed;
1809
1810 vm_acct_memory(pages);
1811
1812 /*
1813 * Sometimes we want to use more memory than we have
1814 */
1815 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1816 return 0;
1817
1818 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1819 unsigned long n;
1820
Christoph Lameter347ce432006-06-30 01:55:35 -07001821 free = global_page_state(NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822 free += nr_swap_pages;
1823
1824 /*
1825 * Any slabs which are created with the
1826 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1827 * which are reclaimable, under pressure. The dentry
1828 * cache and most inode caches should fall into this
1829 */
Christoph Lameter972d1a72006-09-25 23:31:51 -07001830 free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831
1832 /*
1833 * Leave the last 3% for root
1834 */
1835 if (!cap_sys_admin)
1836 free -= free / 32;
1837
1838 if (free > pages)
1839 return 0;
1840
1841 /*
1842 * nr_free_pages() is very expensive on large systems,
1843 * only call if we're about to fail.
1844 */
1845 n = nr_free_pages();
Hideo AOKId5ddc792006-04-10 22:53:01 -07001846
1847 /*
1848 * Leave reserved pages. The pages are not for anonymous pages.
1849 */
1850 if (n <= totalreserve_pages)
1851 goto error;
1852 else
1853 n -= totalreserve_pages;
1854
1855 /*
1856 * Leave the last 3% for root
1857 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858 if (!cap_sys_admin)
1859 n -= n / 32;
1860 free += n;
1861
1862 if (free > pages)
1863 return 0;
Hideo AOKId5ddc792006-04-10 22:53:01 -07001864
1865 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 }
1867
1868 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1869 /*
1870 * Leave the last 3% for root
1871 */
1872 if (!cap_sys_admin)
1873 allowed -= allowed / 32;
1874 allowed += total_swap_pages;
1875
1876 /* Don't let a single process grow too big:
1877 leave 3% of the size of this process for other processes */
Alan Cox731572d2008-10-29 14:01:20 -07001878 if (mm)
1879 allowed -= mm->total_vm / 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -07001881 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 return 0;
KOSAKI Motohiro00a62ce2009-04-30 15:08:51 -07001883
Hideo AOKId5ddc792006-04-10 22:53:01 -07001884error:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885 vm_unacct_memory(pages);
1886
1887 return -ENOMEM;
1888}
1889
1890int in_gate_area_no_task(unsigned long addr)
1891{
1892 return 0;
1893}
David Howellsb0e15192006-01-06 00:11:42 -08001894
Nick Piggind0217ac2007-07-19 01:47:03 -07001895int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
David Howellsb0e15192006-01-06 00:11:42 -08001896{
1897 BUG();
Nick Piggind0217ac2007-07-19 01:47:03 -07001898 return 0;
David Howellsb0e15192006-01-06 00:11:42 -08001899}
Paul Mundtb5073172007-07-21 04:37:25 -07001900EXPORT_SYMBOL(filemap_fault);
David Howells0ec76a12006-09-27 01:50:15 -07001901
1902/*
1903 * Access another process' address space.
1904 * - source/target buffer must be kernel space
1905 */
1906int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1907{
David Howells0ec76a12006-09-27 01:50:15 -07001908 struct vm_area_struct *vma;
1909 struct mm_struct *mm;
1910
1911 if (addr + len < addr)
1912 return 0;
1913
1914 mm = get_task_mm(tsk);
1915 if (!mm)
1916 return 0;
1917
1918 down_read(&mm->mmap_sem);
1919
1920 /* the access must start within one of the target process's mappings */
David Howells0159b142006-09-27 01:50:16 -07001921 vma = find_vma(mm, addr);
1922 if (vma) {
David Howells0ec76a12006-09-27 01:50:15 -07001923 /* don't overrun this mapping */
1924 if (addr + len >= vma->vm_end)
1925 len = vma->vm_end - addr;
1926
1927 /* only read or write mappings where it is permitted */
David Howellsd00c7b92006-09-27 01:50:19 -07001928 if (write && vma->vm_flags & VM_MAYWRITE)
Jie Zhang79597222010-01-06 17:23:28 +00001929 copy_to_user_page(vma, NULL, addr,
1930 (void *) addr, buf, len);
David Howellsd00c7b92006-09-27 01:50:19 -07001931 else if (!write && vma->vm_flags & VM_MAYREAD)
Jie Zhang79597222010-01-06 17:23:28 +00001932 copy_from_user_page(vma, NULL, addr,
1933 buf, (void *) addr, len);
David Howells0ec76a12006-09-27 01:50:15 -07001934 else
1935 len = 0;
1936 } else {
1937 len = 0;
1938 }
1939
1940 up_read(&mm->mmap_sem);
1941 mmput(mm);
1942 return len;
1943}
David Howells7e660872010-01-15 17:01:39 -08001944
1945/**
1946 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1947 * @inode: The inode to check
1948 * @size: The current filesize of the inode
1949 * @newsize: The proposed filesize of the inode
1950 *
1951 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1952 * make sure that that any outstanding VMAs aren't broken and then shrink the
1953 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1954 * automatically grant mappings that are too large.
1955 */
1956int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1957 size_t newsize)
1958{
1959 struct vm_area_struct *vma;
1960 struct prio_tree_iter iter;
1961 struct vm_region *region;
1962 pgoff_t low, high;
1963 size_t r_size, r_top;
1964
1965 low = newsize >> PAGE_SHIFT;
1966 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1967
1968 down_write(&nommu_region_sem);
1969
1970 /* search for VMAs that fall within the dead zone */
1971 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
1972 low, high) {
1973 /* found one - only interested if it's shared out of the page
1974 * cache */
1975 if (vma->vm_flags & VM_SHARED) {
1976 up_write(&nommu_region_sem);
1977 return -ETXTBSY; /* not quite true, but near enough */
1978 }
1979 }
1980
1981 /* reduce any regions that overlap the dead zone - if in existence,
1982 * these will be pointed to by VMAs that don't overlap the dead zone
1983 *
1984 * we don't check for any regions that start beyond the EOF as there
1985 * shouldn't be any
1986 */
1987 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
1988 0, ULONG_MAX) {
1989 if (!(vma->vm_flags & VM_SHARED))
1990 continue;
1991
1992 region = vma->vm_region;
1993 r_size = region->vm_top - region->vm_start;
1994 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1995
1996 if (r_top > newsize) {
1997 region->vm_top -= r_top - newsize;
1998 if (region->vm_end > region->vm_top)
1999 region->vm_end = region->vm_top;
2000 }
2001 }
2002
2003 up_write(&nommu_region_sem);
2004 return 0;
2005}