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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/nommu.c
4 *
5 * Replacement code for mm functions to support CPU's that don't
6 * have any form of memory management unit (thus no virtual memory).
7 *
8 * See Documentation/admin-guide/mm/nommu-mmap.rst
9 *
10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/export.h>
20#include <linux/mm.h>
21#include <linux/sched/mm.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/backing-dev.h>
30#include <linux/compiler.h>
31#include <linux/mount.h>
32#include <linux/personality.h>
33#include <linux/security.h>
34#include <linux/syscalls.h>
35#include <linux/audit.h>
36#include <linux/printk.h>
37
38#include <linux/uaccess.h>
39#include <linux/uio.h>
40#include <asm/tlb.h>
41#include <asm/tlbflush.h>
42#include <asm/mmu_context.h>
43#include "internal.h"
44
45void *high_memory;
46EXPORT_SYMBOL(high_memory);
47struct page *mem_map;
48unsigned long max_mapnr;
49EXPORT_SYMBOL(max_mapnr);
50unsigned long highest_memmap_pfn;
51int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
52int heap_stack_gap = 0;
53
54atomic_long_t mmap_pages_allocated;
55
56EXPORT_SYMBOL(mem_map);
57
58/* list of mapped, potentially shareable regions */
59static struct kmem_cache *vm_region_jar;
60struct rb_root nommu_region_tree = RB_ROOT;
61DECLARE_RWSEM(nommu_region_sem);
62
63const 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 */
72unsigned 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(page);
111}
112
113/**
114 * follow_pfn - look up PFN at a user virtual address
115 * @vma: memory mapping
116 * @address: user virtual address
117 * @pfn: location to store found PFN
118 *
119 * Only IO mappings and raw PFN mappings are allowed.
120 *
121 * Returns zero and the pfn at @pfn on success, -ve otherwise.
122 */
123int follow_pfn(struct vm_area_struct *vma, unsigned long address,
124 unsigned long *pfn)
125{
126 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
127 return -EINVAL;
128
129 *pfn = address >> PAGE_SHIFT;
130 return 0;
131}
132EXPORT_SYMBOL(follow_pfn);
133
134LIST_HEAD(vmap_area_list);
135
136void vfree(const void *addr)
137{
138 kfree(addr);
139}
140EXPORT_SYMBOL(vfree);
141
142void *__vmalloc(unsigned long size, gfp_t gfp_mask)
143{
144 /*
145 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
146 * returns only a logical address.
147 */
148 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
149}
150EXPORT_SYMBOL(__vmalloc);
151
152void *__vmalloc_node_range(unsigned long size, unsigned long align,
153 unsigned long start, unsigned long end, gfp_t gfp_mask,
154 pgprot_t prot, unsigned long vm_flags, int node,
155 const void *caller)
156{
157 return __vmalloc(size, gfp_mask);
158}
159
160void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
161 int node, const void *caller)
162{
163 return __vmalloc(size, gfp_mask);
164}
165
166static void *__vmalloc_user_flags(unsigned long size, gfp_t flags)
167{
168 void *ret;
169
170 ret = __vmalloc(size, flags);
171 if (ret) {
172 struct vm_area_struct *vma;
173
174 mmap_write_lock(current->mm);
175 vma = find_vma(current->mm, (unsigned long)ret);
176 if (vma)
177 vm_flags_set(vma, VM_USERMAP);
178 mmap_write_unlock(current->mm);
179 }
180
181 return ret;
182}
183
184void *vmalloc_user(unsigned long size)
185{
186 return __vmalloc_user_flags(size, GFP_KERNEL | __GFP_ZERO);
187}
188EXPORT_SYMBOL(vmalloc_user);
189
190struct page *vmalloc_to_page(const void *addr)
191{
192 return virt_to_page(addr);
193}
194EXPORT_SYMBOL(vmalloc_to_page);
195
196unsigned long vmalloc_to_pfn(const void *addr)
197{
198 return page_to_pfn(virt_to_page(addr));
199}
200EXPORT_SYMBOL(vmalloc_to_pfn);
201
202long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
203{
204 /* Don't allow overflow */
205 if ((unsigned long) addr + count < count)
206 count = -(unsigned long) addr;
207
208 return copy_to_iter(addr, count, iter);
209}
210
211/*
212 * vmalloc - allocate virtually contiguous memory
213 *
214 * @size: allocation size
215 *
216 * Allocate enough pages to cover @size from the page level
217 * allocator and map them into contiguous kernel virtual space.
218 *
219 * For tight control over page level allocator and protection flags
220 * use __vmalloc() instead.
221 */
222void *vmalloc(unsigned long size)
223{
224 return __vmalloc(size, GFP_KERNEL);
225}
226EXPORT_SYMBOL(vmalloc);
227
228void *vmalloc_huge(unsigned long size, gfp_t gfp_mask) __weak __alias(__vmalloc);
229
230/*
231 * vzalloc - allocate virtually contiguous memory with zero fill
232 *
233 * @size: allocation size
234 *
235 * Allocate enough pages to cover @size from the page level
236 * allocator and map them into contiguous kernel virtual space.
237 * The memory allocated is set to zero.
238 *
239 * For tight control over page level allocator and protection flags
240 * use __vmalloc() instead.
241 */
242void *vzalloc(unsigned long size)
243{
244 return __vmalloc(size, GFP_KERNEL | __GFP_ZERO);
245}
246EXPORT_SYMBOL(vzalloc);
247
248/**
249 * vmalloc_node - allocate memory on a specific node
250 * @size: allocation size
251 * @node: numa node
252 *
253 * Allocate enough pages to cover @size from the page level
254 * allocator and map them into contiguous kernel virtual space.
255 *
256 * For tight control over page level allocator and protection flags
257 * use __vmalloc() instead.
258 */
259void *vmalloc_node(unsigned long size, int node)
260{
261 return vmalloc(size);
262}
263EXPORT_SYMBOL(vmalloc_node);
264
265/**
266 * vzalloc_node - allocate memory on a specific node with zero fill
267 * @size: allocation size
268 * @node: numa node
269 *
270 * Allocate enough pages to cover @size from the page level
271 * allocator and map them into contiguous kernel virtual space.
272 * The memory allocated is set to zero.
273 *
274 * For tight control over page level allocator and protection flags
275 * use __vmalloc() instead.
276 */
277void *vzalloc_node(unsigned long size, int node)
278{
279 return vzalloc(size);
280}
281EXPORT_SYMBOL(vzalloc_node);
282
283/**
284 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
285 * @size: allocation size
286 *
287 * Allocate enough 32bit PA addressable pages to cover @size from the
288 * page level allocator and map them into contiguous kernel virtual space.
289 */
290void *vmalloc_32(unsigned long size)
291{
292 return __vmalloc(size, GFP_KERNEL);
293}
294EXPORT_SYMBOL(vmalloc_32);
295
296/**
297 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
298 * @size: allocation size
299 *
300 * The resulting memory area is 32bit addressable and zeroed so it can be
301 * mapped to userspace without leaking data.
302 *
303 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
304 * remap_vmalloc_range() are permissible.
305 */
306void *vmalloc_32_user(unsigned long size)
307{
308 /*
309 * We'll have to sort out the ZONE_DMA bits for 64-bit,
310 * but for now this can simply use vmalloc_user() directly.
311 */
312 return vmalloc_user(size);
313}
314EXPORT_SYMBOL(vmalloc_32_user);
315
316void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
317{
318 BUG();
319 return NULL;
320}
321EXPORT_SYMBOL(vmap);
322
323void vunmap(const void *addr)
324{
325 BUG();
326}
327EXPORT_SYMBOL(vunmap);
328
329void *vm_map_ram(struct page **pages, unsigned int count, int node)
330{
331 BUG();
332 return NULL;
333}
334EXPORT_SYMBOL(vm_map_ram);
335
336void vm_unmap_ram(const void *mem, unsigned int count)
337{
338 BUG();
339}
340EXPORT_SYMBOL(vm_unmap_ram);
341
342void vm_unmap_aliases(void)
343{
344}
345EXPORT_SYMBOL_GPL(vm_unmap_aliases);
346
347void free_vm_area(struct vm_struct *area)
348{
349 BUG();
350}
351EXPORT_SYMBOL_GPL(free_vm_area);
352
353int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
354 struct page *page)
355{
356 return -EINVAL;
357}
358EXPORT_SYMBOL(vm_insert_page);
359
360int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
361 unsigned long num)
362{
363 return -EINVAL;
364}
365EXPORT_SYMBOL(vm_map_pages);
366
367int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
368 unsigned long num)
369{
370 return -EINVAL;
371}
372EXPORT_SYMBOL(vm_map_pages_zero);
373
374/*
375 * sys_brk() for the most part doesn't need the global kernel
376 * lock, except when an application is doing something nasty
377 * like trying to un-brk an area that has already been mapped
378 * to a regular file. in this case, the unmapping will need
379 * to invoke file system routines that need the global lock.
380 */
381SYSCALL_DEFINE1(brk, unsigned long, brk)
382{
383 struct mm_struct *mm = current->mm;
384
385 if (brk < mm->start_brk || brk > mm->context.end_brk)
386 return mm->brk;
387
388 if (mm->brk == brk)
389 return mm->brk;
390
391 /*
392 * Always allow shrinking brk
393 */
394 if (brk <= mm->brk) {
395 mm->brk = brk;
396 return brk;
397 }
398
399 /*
400 * Ok, looks good - let it rip.
401 */
402 flush_icache_user_range(mm->brk, brk);
403 return mm->brk = brk;
404}
405
406/*
407 * initialise the percpu counter for VM and region record slabs
408 */
409void __init mmap_init(void)
410{
411 int ret;
412
413 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
414 VM_BUG_ON(ret);
415 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
416}
417
418/*
419 * validate the region tree
420 * - the caller must hold the region lock
421 */
422#ifdef CONFIG_DEBUG_NOMMU_REGIONS
423static noinline void validate_nommu_regions(void)
424{
425 struct vm_region *region, *last;
426 struct rb_node *p, *lastp;
427
428 lastp = rb_first(&nommu_region_tree);
429 if (!lastp)
430 return;
431
432 last = rb_entry(lastp, struct vm_region, vm_rb);
433 BUG_ON(last->vm_end <= last->vm_start);
434 BUG_ON(last->vm_top < last->vm_end);
435
436 while ((p = rb_next(lastp))) {
437 region = rb_entry(p, struct vm_region, vm_rb);
438 last = rb_entry(lastp, struct vm_region, vm_rb);
439
440 BUG_ON(region->vm_end <= region->vm_start);
441 BUG_ON(region->vm_top < region->vm_end);
442 BUG_ON(region->vm_start < last->vm_top);
443
444 lastp = p;
445 }
446}
447#else
448static void validate_nommu_regions(void)
449{
450}
451#endif
452
453/*
454 * add a region into the global tree
455 */
456static void add_nommu_region(struct vm_region *region)
457{
458 struct vm_region *pregion;
459 struct rb_node **p, *parent;
460
461 validate_nommu_regions();
462
463 parent = NULL;
464 p = &nommu_region_tree.rb_node;
465 while (*p) {
466 parent = *p;
467 pregion = rb_entry(parent, struct vm_region, vm_rb);
468 if (region->vm_start < pregion->vm_start)
469 p = &(*p)->rb_left;
470 else if (region->vm_start > pregion->vm_start)
471 p = &(*p)->rb_right;
472 else if (pregion == region)
473 return;
474 else
475 BUG();
476 }
477
478 rb_link_node(®ion->vm_rb, parent, p);
479 rb_insert_color(®ion->vm_rb, &nommu_region_tree);
480
481 validate_nommu_regions();
482}
483
484/*
485 * delete a region from the global tree
486 */
487static void delete_nommu_region(struct vm_region *region)
488{
489 BUG_ON(!nommu_region_tree.rb_node);
490
491 validate_nommu_regions();
492 rb_erase(®ion->vm_rb, &nommu_region_tree);
493 validate_nommu_regions();
494}
495
496/*
497 * free a contiguous series of pages
498 */
499static void free_page_series(unsigned long from, unsigned long to)
500{
501 for (; from < to; from += PAGE_SIZE) {
502 struct page *page = virt_to_page((void *)from);
503
504 atomic_long_dec(&mmap_pages_allocated);
505 put_page(page);
506 }
507}
508
509/*
510 * release a reference to a region
511 * - the caller must hold the region semaphore for writing, which this releases
512 * - the region may not have been added to the tree yet, in which case vm_top
513 * will equal vm_start
514 */
515static void __put_nommu_region(struct vm_region *region)
516 __releases(nommu_region_sem)
517{
518 BUG_ON(!nommu_region_tree.rb_node);
519
520 if (--region->vm_usage == 0) {
521 if (region->vm_top > region->vm_start)
522 delete_nommu_region(region);
523 up_write(&nommu_region_sem);
524
525 if (region->vm_file)
526 fput(region->vm_file);
527
528 /* IO memory and memory shared directly out of the pagecache
529 * from ramfs/tmpfs mustn't be released here */
530 if (region->vm_flags & VM_MAPPED_COPY)
531 free_page_series(region->vm_start, region->vm_top);
532 kmem_cache_free(vm_region_jar, region);
533 } else {
534 up_write(&nommu_region_sem);
535 }
536}
537
538/*
539 * release a reference to a region
540 */
541static void put_nommu_region(struct vm_region *region)
542{
543 down_write(&nommu_region_sem);
544 __put_nommu_region(region);
545}
546
547static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
548{
549 vma->vm_mm = mm;
550
551 /* add the VMA to the mapping */
552 if (vma->vm_file) {
553 struct address_space *mapping = vma->vm_file->f_mapping;
554
555 i_mmap_lock_write(mapping);
556 flush_dcache_mmap_lock(mapping);
557 vma_interval_tree_insert(vma, &mapping->i_mmap);
558 flush_dcache_mmap_unlock(mapping);
559 i_mmap_unlock_write(mapping);
560 }
561}
562
563static void cleanup_vma_from_mm(struct vm_area_struct *vma)
564{
565 vma->vm_mm->map_count--;
566 /* remove the VMA from the mapping */
567 if (vma->vm_file) {
568 struct address_space *mapping;
569 mapping = vma->vm_file->f_mapping;
570
571 i_mmap_lock_write(mapping);
572 flush_dcache_mmap_lock(mapping);
573 vma_interval_tree_remove(vma, &mapping->i_mmap);
574 flush_dcache_mmap_unlock(mapping);
575 i_mmap_unlock_write(mapping);
576 }
577}
578
579/*
580 * delete a VMA from its owning mm_struct and address space
581 */
582static int delete_vma_from_mm(struct vm_area_struct *vma)
583{
584 VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start);
585
586 vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
587 if (vma_iter_prealloc(&vmi, vma)) {
588 pr_warn("Allocation of vma tree for process %d failed\n",
589 current->pid);
590 return -ENOMEM;
591 }
592 cleanup_vma_from_mm(vma);
593
594 /* remove from the MM's tree and list */
595 vma_iter_clear(&vmi);
596 return 0;
597}
598/*
599 * destroy a VMA record
600 */
601static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
602{
603 if (vma->vm_ops && vma->vm_ops->close)
604 vma->vm_ops->close(vma);
605 if (vma->vm_file)
606 fput(vma->vm_file);
607 put_nommu_region(vma->vm_region);
608 vm_area_free(vma);
609}
610
611struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
612 unsigned long start_addr,
613 unsigned long end_addr)
614{
615 unsigned long index = start_addr;
616
617 mmap_assert_locked(mm);
618 return mt_find(&mm->mm_mt, &index, end_addr - 1);
619}
620EXPORT_SYMBOL(find_vma_intersection);
621
622/*
623 * look up the first VMA in which addr resides, NULL if none
624 * - should be called with mm->mmap_lock at least held readlocked
625 */
626struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
627{
628 VMA_ITERATOR(vmi, mm, addr);
629
630 return vma_iter_load(&vmi);
631}
632EXPORT_SYMBOL(find_vma);
633
634/*
635 * At least xtensa ends up having protection faults even with no
636 * MMU.. No stack expansion, at least.
637 */
638struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
639 unsigned long addr, struct pt_regs *regs)
640{
641 struct vm_area_struct *vma;
642
643 mmap_read_lock(mm);
644 vma = vma_lookup(mm, addr);
645 if (!vma)
646 mmap_read_unlock(mm);
647 return vma;
648}
649
650/*
651 * expand a stack to a given address
652 * - not supported under NOMMU conditions
653 */
654int expand_stack_locked(struct vm_area_struct *vma, unsigned long addr)
655{
656 return -ENOMEM;
657}
658
659struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
660{
661 mmap_read_unlock(mm);
662 return NULL;
663}
664
665/*
666 * look up the first VMA exactly that exactly matches addr
667 * - should be called with mm->mmap_lock at least held readlocked
668 */
669static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
670 unsigned long addr,
671 unsigned long len)
672{
673 struct vm_area_struct *vma;
674 unsigned long end = addr + len;
675 VMA_ITERATOR(vmi, mm, addr);
676
677 vma = vma_iter_load(&vmi);
678 if (!vma)
679 return NULL;
680 if (vma->vm_start != addr)
681 return NULL;
682 if (vma->vm_end != end)
683 return NULL;
684
685 return vma;
686}
687
688/*
689 * determine whether a mapping should be permitted and, if so, what sort of
690 * mapping we're capable of supporting
691 */
692static int validate_mmap_request(struct file *file,
693 unsigned long addr,
694 unsigned long len,
695 unsigned long prot,
696 unsigned long flags,
697 unsigned long pgoff,
698 unsigned long *_capabilities)
699{
700 unsigned long capabilities, rlen;
701 int ret;
702
703 /* do the simple checks first */
704 if (flags & MAP_FIXED)
705 return -EINVAL;
706
707 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
708 (flags & MAP_TYPE) != MAP_SHARED)
709 return -EINVAL;
710
711 if (!len)
712 return -EINVAL;
713
714 /* Careful about overflows.. */
715 rlen = PAGE_ALIGN(len);
716 if (!rlen || rlen > TASK_SIZE)
717 return -ENOMEM;
718
719 /* offset overflow? */
720 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
721 return -EOVERFLOW;
722
723 if (file) {
724 /* files must support mmap */
725 if (!file->f_op->mmap)
726 return -ENODEV;
727
728 /* work out if what we've got could possibly be shared
729 * - we support chardevs that provide their own "memory"
730 * - we support files/blockdevs that are memory backed
731 */
732 if (file->f_op->mmap_capabilities) {
733 capabilities = file->f_op->mmap_capabilities(file);
734 } else {
735 /* no explicit capabilities set, so assume some
736 * defaults */
737 switch (file_inode(file)->i_mode & S_IFMT) {
738 case S_IFREG:
739 case S_IFBLK:
740 capabilities = NOMMU_MAP_COPY;
741 break;
742
743 case S_IFCHR:
744 capabilities =
745 NOMMU_MAP_DIRECT |
746 NOMMU_MAP_READ |
747 NOMMU_MAP_WRITE;
748 break;
749
750 default:
751 return -EINVAL;
752 }
753 }
754
755 /* eliminate any capabilities that we can't support on this
756 * device */
757 if (!file->f_op->get_unmapped_area)
758 capabilities &= ~NOMMU_MAP_DIRECT;
759 if (!(file->f_mode & FMODE_CAN_READ))
760 capabilities &= ~NOMMU_MAP_COPY;
761
762 /* The file shall have been opened with read permission. */
763 if (!(file->f_mode & FMODE_READ))
764 return -EACCES;
765
766 if (flags & MAP_SHARED) {
767 /* do checks for writing, appending and locking */
768 if ((prot & PROT_WRITE) &&
769 !(file->f_mode & FMODE_WRITE))
770 return -EACCES;
771
772 if (IS_APPEND(file_inode(file)) &&
773 (file->f_mode & FMODE_WRITE))
774 return -EACCES;
775
776 if (!(capabilities & NOMMU_MAP_DIRECT))
777 return -ENODEV;
778
779 /* we mustn't privatise shared mappings */
780 capabilities &= ~NOMMU_MAP_COPY;
781 } else {
782 /* we're going to read the file into private memory we
783 * allocate */
784 if (!(capabilities & NOMMU_MAP_COPY))
785 return -ENODEV;
786
787 /* we don't permit a private writable mapping to be
788 * shared with the backing device */
789 if (prot & PROT_WRITE)
790 capabilities &= ~NOMMU_MAP_DIRECT;
791 }
792
793 if (capabilities & NOMMU_MAP_DIRECT) {
794 if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) ||
795 ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
796 ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC))
797 ) {
798 capabilities &= ~NOMMU_MAP_DIRECT;
799 if (flags & MAP_SHARED) {
800 pr_warn("MAP_SHARED not completely supported on !MMU\n");
801 return -EINVAL;
802 }
803 }
804 }
805
806 /* handle executable mappings and implied executable
807 * mappings */
808 if (path_noexec(&file->f_path)) {
809 if (prot & PROT_EXEC)
810 return -EPERM;
811 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
812 /* handle implication of PROT_EXEC by PROT_READ */
813 if (current->personality & READ_IMPLIES_EXEC) {
814 if (capabilities & NOMMU_MAP_EXEC)
815 prot |= PROT_EXEC;
816 }
817 } else if ((prot & PROT_READ) &&
818 (prot & PROT_EXEC) &&
819 !(capabilities & NOMMU_MAP_EXEC)
820 ) {
821 /* backing file is not executable, try to copy */
822 capabilities &= ~NOMMU_MAP_DIRECT;
823 }
824 } else {
825 /* anonymous mappings are always memory backed and can be
826 * privately mapped
827 */
828 capabilities = NOMMU_MAP_COPY;
829
830 /* handle PROT_EXEC implication by PROT_READ */
831 if ((prot & PROT_READ) &&
832 (current->personality & READ_IMPLIES_EXEC))
833 prot |= PROT_EXEC;
834 }
835
836 /* allow the security API to have its say */
837 ret = security_mmap_addr(addr);
838 if (ret < 0)
839 return ret;
840
841 /* looks okay */
842 *_capabilities = capabilities;
843 return 0;
844}
845
846/*
847 * we've determined that we can make the mapping, now translate what we
848 * now know into VMA flags
849 */
850static unsigned long determine_vm_flags(struct file *file,
851 unsigned long prot,
852 unsigned long flags,
853 unsigned long capabilities)
854{
855 unsigned long vm_flags;
856
857 vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
858
859 if (!file) {
860 /*
861 * MAP_ANONYMOUS. MAP_SHARED is mapped to MAP_PRIVATE, because
862 * there is no fork().
863 */
864 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
865 } else if (flags & MAP_PRIVATE) {
866 /* MAP_PRIVATE file mapping */
867 if (capabilities & NOMMU_MAP_DIRECT)
868 vm_flags |= (capabilities & NOMMU_VMFLAGS);
869 else
870 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
871
872 if (!(prot & PROT_WRITE) && !current->ptrace)
873 /*
874 * R/O private file mapping which cannot be used to
875 * modify memory, especially also not via active ptrace
876 * (e.g., set breakpoints) or later by upgrading
877 * permissions (no mprotect()). We can try overlaying
878 * the file mapping, which will work e.g., on chardevs,
879 * ramfs/tmpfs/shmfs and romfs/cramf.
880 */
881 vm_flags |= VM_MAYOVERLAY;
882 } else {
883 /* MAP_SHARED file mapping: NOMMU_MAP_DIRECT is set. */
884 vm_flags |= VM_SHARED | VM_MAYSHARE |
885 (capabilities & NOMMU_VMFLAGS);
886 }
887
888 return vm_flags;
889}
890
891/*
892 * set up a shared mapping on a file (the driver or filesystem provides and
893 * pins the storage)
894 */
895static int do_mmap_shared_file(struct vm_area_struct *vma)
896{
897 int ret;
898
899 ret = call_mmap(vma->vm_file, vma);
900 if (ret == 0) {
901 vma->vm_region->vm_top = vma->vm_region->vm_end;
902 return 0;
903 }
904 if (ret != -ENOSYS)
905 return ret;
906
907 /* getting -ENOSYS indicates that direct mmap isn't possible (as
908 * opposed to tried but failed) so we can only give a suitable error as
909 * it's not possible to make a private copy if MAP_SHARED was given */
910 return -ENODEV;
911}
912
913/*
914 * set up a private mapping or an anonymous shared mapping
915 */
916static int do_mmap_private(struct vm_area_struct *vma,
917 struct vm_region *region,
918 unsigned long len,
919 unsigned long capabilities)
920{
921 unsigned long total, point;
922 void *base;
923 int ret, order;
924
925 /*
926 * Invoke the file's mapping function so that it can keep track of
927 * shared mappings on devices or memory. VM_MAYOVERLAY will be set if
928 * it may attempt to share, which will make is_nommu_shared_mapping()
929 * happy.
930 */
931 if (capabilities & NOMMU_MAP_DIRECT) {
932 ret = call_mmap(vma->vm_file, vma);
933 /* shouldn't return success if we're not sharing */
934 if (WARN_ON_ONCE(!is_nommu_shared_mapping(vma->vm_flags)))
935 ret = -ENOSYS;
936 if (ret == 0) {
937 vma->vm_region->vm_top = vma->vm_region->vm_end;
938 return 0;
939 }
940 if (ret != -ENOSYS)
941 return ret;
942
943 /* getting an ENOSYS error indicates that direct mmap isn't
944 * possible (as opposed to tried but failed) so we'll try to
945 * make a private copy of the data and map that instead */
946 }
947
948
949 /* allocate some memory to hold the mapping
950 * - note that this may not return a page-aligned address if the object
951 * we're allocating is smaller than a page
952 */
953 order = get_order(len);
954 total = 1 << order;
955 point = len >> PAGE_SHIFT;
956
957 /* we don't want to allocate a power-of-2 sized page set */
958 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
959 total = point;
960
961 base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
962 if (!base)
963 goto enomem;
964
965 atomic_long_add(total, &mmap_pages_allocated);
966
967 vm_flags_set(vma, VM_MAPPED_COPY);
968 region->vm_flags = vma->vm_flags;
969 region->vm_start = (unsigned long) base;
970 region->vm_end = region->vm_start + len;
971 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
972
973 vma->vm_start = region->vm_start;
974 vma->vm_end = region->vm_start + len;
975
976 if (vma->vm_file) {
977 /* read the contents of a file into the copy */
978 loff_t fpos;
979
980 fpos = vma->vm_pgoff;
981 fpos <<= PAGE_SHIFT;
982
983 ret = kernel_read(vma->vm_file, base, len, &fpos);
984 if (ret < 0)
985 goto error_free;
986
987 /* clear the last little bit */
988 if (ret < len)
989 memset(base + ret, 0, len - ret);
990
991 } else {
992 vma_set_anonymous(vma);
993 }
994
995 return 0;
996
997error_free:
998 free_page_series(region->vm_start, region->vm_top);
999 region->vm_start = vma->vm_start = 0;
1000 region->vm_end = vma->vm_end = 0;
1001 region->vm_top = 0;
1002 return ret;
1003
1004enomem:
1005 pr_err("Allocation of length %lu from process %d (%s) failed\n",
1006 len, current->pid, current->comm);
1007 show_mem();
1008 return -ENOMEM;
1009}
1010
1011/*
1012 * handle mapping creation for uClinux
1013 */
1014unsigned long do_mmap(struct file *file,
1015 unsigned long addr,
1016 unsigned long len,
1017 unsigned long prot,
1018 unsigned long flags,
1019 vm_flags_t vm_flags,
1020 unsigned long pgoff,
1021 unsigned long *populate,
1022 struct list_head *uf)
1023{
1024 struct vm_area_struct *vma;
1025 struct vm_region *region;
1026 struct rb_node *rb;
1027 unsigned long capabilities, result;
1028 int ret;
1029 VMA_ITERATOR(vmi, current->mm, 0);
1030
1031 *populate = 0;
1032
1033 /* decide whether we should attempt the mapping, and if so what sort of
1034 * mapping */
1035 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1036 &capabilities);
1037 if (ret < 0)
1038 return ret;
1039
1040 /* we ignore the address hint */
1041 addr = 0;
1042 len = PAGE_ALIGN(len);
1043
1044 /* we've determined that we can make the mapping, now translate what we
1045 * now know into VMA flags */
1046 vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1047
1048
1049 /* we're going to need to record the mapping */
1050 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1051 if (!region)
1052 goto error_getting_region;
1053
1054 vma = vm_area_alloc(current->mm);
1055 if (!vma)
1056 goto error_getting_vma;
1057
1058 region->vm_usage = 1;
1059 region->vm_flags = vm_flags;
1060 region->vm_pgoff = pgoff;
1061
1062 vm_flags_init(vma, vm_flags);
1063 vma->vm_pgoff = pgoff;
1064
1065 if (file) {
1066 region->vm_file = get_file(file);
1067 vma->vm_file = get_file(file);
1068 }
1069
1070 down_write(&nommu_region_sem);
1071
1072 /* if we want to share, we need to check for regions created by other
1073 * mmap() calls that overlap with our proposed mapping
1074 * - we can only share with a superset match on most regular files
1075 * - shared mappings on character devices and memory backed files are
1076 * permitted to overlap inexactly as far as we are concerned for in
1077 * these cases, sharing is handled in the driver or filesystem rather
1078 * than here
1079 */
1080 if (is_nommu_shared_mapping(vm_flags)) {
1081 struct vm_region *pregion;
1082 unsigned long pglen, rpglen, pgend, rpgend, start;
1083
1084 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1085 pgend = pgoff + pglen;
1086
1087 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1088 pregion = rb_entry(rb, struct vm_region, vm_rb);
1089
1090 if (!is_nommu_shared_mapping(pregion->vm_flags))
1091 continue;
1092
1093 /* search for overlapping mappings on the same file */
1094 if (file_inode(pregion->vm_file) !=
1095 file_inode(file))
1096 continue;
1097
1098 if (pregion->vm_pgoff >= pgend)
1099 continue;
1100
1101 rpglen = pregion->vm_end - pregion->vm_start;
1102 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1103 rpgend = pregion->vm_pgoff + rpglen;
1104 if (pgoff >= rpgend)
1105 continue;
1106
1107 /* handle inexactly overlapping matches between
1108 * mappings */
1109 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1110 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1111 /* new mapping is not a subset of the region */
1112 if (!(capabilities & NOMMU_MAP_DIRECT))
1113 goto sharing_violation;
1114 continue;
1115 }
1116
1117 /* we've found a region we can share */
1118 pregion->vm_usage++;
1119 vma->vm_region = pregion;
1120 start = pregion->vm_start;
1121 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1122 vma->vm_start = start;
1123 vma->vm_end = start + len;
1124
1125 if (pregion->vm_flags & VM_MAPPED_COPY)
1126 vm_flags_set(vma, VM_MAPPED_COPY);
1127 else {
1128 ret = do_mmap_shared_file(vma);
1129 if (ret < 0) {
1130 vma->vm_region = NULL;
1131 vma->vm_start = 0;
1132 vma->vm_end = 0;
1133 pregion->vm_usage--;
1134 pregion = NULL;
1135 goto error_just_free;
1136 }
1137 }
1138 fput(region->vm_file);
1139 kmem_cache_free(vm_region_jar, region);
1140 region = pregion;
1141 result = start;
1142 goto share;
1143 }
1144
1145 /* obtain the address at which to make a shared mapping
1146 * - this is the hook for quasi-memory character devices to
1147 * tell us the location of a shared mapping
1148 */
1149 if (capabilities & NOMMU_MAP_DIRECT) {
1150 addr = file->f_op->get_unmapped_area(file, addr, len,
1151 pgoff, flags);
1152 if (IS_ERR_VALUE(addr)) {
1153 ret = addr;
1154 if (ret != -ENOSYS)
1155 goto error_just_free;
1156
1157 /* the driver refused to tell us where to site
1158 * the mapping so we'll have to attempt to copy
1159 * it */
1160 ret = -ENODEV;
1161 if (!(capabilities & NOMMU_MAP_COPY))
1162 goto error_just_free;
1163
1164 capabilities &= ~NOMMU_MAP_DIRECT;
1165 } else {
1166 vma->vm_start = region->vm_start = addr;
1167 vma->vm_end = region->vm_end = addr + len;
1168 }
1169 }
1170 }
1171
1172 vma->vm_region = region;
1173
1174 /* set up the mapping
1175 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1176 */
1177 if (file && vma->vm_flags & VM_SHARED)
1178 ret = do_mmap_shared_file(vma);
1179 else
1180 ret = do_mmap_private(vma, region, len, capabilities);
1181 if (ret < 0)
1182 goto error_just_free;
1183 add_nommu_region(region);
1184
1185 /* clear anonymous mappings that don't ask for uninitialized data */
1186 if (!vma->vm_file &&
1187 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
1188 !(flags & MAP_UNINITIALIZED)))
1189 memset((void *)region->vm_start, 0,
1190 region->vm_end - region->vm_start);
1191
1192 /* okay... we have a mapping; now we have to register it */
1193 result = vma->vm_start;
1194
1195 current->mm->total_vm += len >> PAGE_SHIFT;
1196
1197share:
1198 BUG_ON(!vma->vm_region);
1199 vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
1200 if (vma_iter_prealloc(&vmi, vma))
1201 goto error_just_free;
1202
1203 setup_vma_to_mm(vma, current->mm);
1204 current->mm->map_count++;
1205 /* add the VMA to the tree */
1206 vma_iter_store(&vmi, vma);
1207
1208 /* we flush the region from the icache only when the first executable
1209 * mapping of it is made */
1210 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1211 flush_icache_user_range(region->vm_start, region->vm_end);
1212 region->vm_icache_flushed = true;
1213 }
1214
1215 up_write(&nommu_region_sem);
1216
1217 return result;
1218
1219error_just_free:
1220 up_write(&nommu_region_sem);
1221error:
1222 vma_iter_free(&vmi);
1223 if (region->vm_file)
1224 fput(region->vm_file);
1225 kmem_cache_free(vm_region_jar, region);
1226 if (vma->vm_file)
1227 fput(vma->vm_file);
1228 vm_area_free(vma);
1229 return ret;
1230
1231sharing_violation:
1232 up_write(&nommu_region_sem);
1233 pr_warn("Attempt to share mismatched mappings\n");
1234 ret = -EINVAL;
1235 goto error;
1236
1237error_getting_vma:
1238 kmem_cache_free(vm_region_jar, region);
1239 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1240 len, current->pid);
1241 show_mem();
1242 return -ENOMEM;
1243
1244error_getting_region:
1245 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1246 len, current->pid);
1247 show_mem();
1248 return -ENOMEM;
1249}
1250
1251unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1252 unsigned long prot, unsigned long flags,
1253 unsigned long fd, unsigned long pgoff)
1254{
1255 struct file *file = NULL;
1256 unsigned long retval = -EBADF;
1257
1258 audit_mmap_fd(fd, flags);
1259 if (!(flags & MAP_ANONYMOUS)) {
1260 file = fget(fd);
1261 if (!file)
1262 goto out;
1263 }
1264
1265 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1266
1267 if (file)
1268 fput(file);
1269out:
1270 return retval;
1271}
1272
1273SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1274 unsigned long, prot, unsigned long, flags,
1275 unsigned long, fd, unsigned long, pgoff)
1276{
1277 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1278}
1279
1280#ifdef __ARCH_WANT_SYS_OLD_MMAP
1281struct mmap_arg_struct {
1282 unsigned long addr;
1283 unsigned long len;
1284 unsigned long prot;
1285 unsigned long flags;
1286 unsigned long fd;
1287 unsigned long offset;
1288};
1289
1290SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1291{
1292 struct mmap_arg_struct a;
1293
1294 if (copy_from_user(&a, arg, sizeof(a)))
1295 return -EFAULT;
1296 if (offset_in_page(a.offset))
1297 return -EINVAL;
1298
1299 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1300 a.offset >> PAGE_SHIFT);
1301}
1302#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1303
1304/*
1305 * split a vma into two pieces at address 'addr', a new vma is allocated either
1306 * for the first part or the tail.
1307 */
1308static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
1309 unsigned long addr, int new_below)
1310{
1311 struct vm_area_struct *new;
1312 struct vm_region *region;
1313 unsigned long npages;
1314 struct mm_struct *mm;
1315
1316 /* we're only permitted to split anonymous regions (these should have
1317 * only a single usage on the region) */
1318 if (vma->vm_file)
1319 return -ENOMEM;
1320
1321 mm = vma->vm_mm;
1322 if (mm->map_count >= sysctl_max_map_count)
1323 return -ENOMEM;
1324
1325 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1326 if (!region)
1327 return -ENOMEM;
1328
1329 new = vm_area_dup(vma);
1330 if (!new)
1331 goto err_vma_dup;
1332
1333 /* most fields are the same, copy all, and then fixup */
1334 *region = *vma->vm_region;
1335 new->vm_region = region;
1336
1337 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1338
1339 if (new_below) {
1340 region->vm_top = region->vm_end = new->vm_end = addr;
1341 } else {
1342 region->vm_start = new->vm_start = addr;
1343 region->vm_pgoff = new->vm_pgoff += npages;
1344 }
1345
1346 vma_iter_config(vmi, new->vm_start, new->vm_end);
1347 if (vma_iter_prealloc(vmi, vma)) {
1348 pr_warn("Allocation of vma tree for process %d failed\n",
1349 current->pid);
1350 goto err_vmi_preallocate;
1351 }
1352
1353 if (new->vm_ops && new->vm_ops->open)
1354 new->vm_ops->open(new);
1355
1356 down_write(&nommu_region_sem);
1357 delete_nommu_region(vma->vm_region);
1358 if (new_below) {
1359 vma->vm_region->vm_start = vma->vm_start = addr;
1360 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1361 } else {
1362 vma->vm_region->vm_end = vma->vm_end = addr;
1363 vma->vm_region->vm_top = addr;
1364 }
1365 add_nommu_region(vma->vm_region);
1366 add_nommu_region(new->vm_region);
1367 up_write(&nommu_region_sem);
1368
1369 setup_vma_to_mm(vma, mm);
1370 setup_vma_to_mm(new, mm);
1371 vma_iter_store(vmi, new);
1372 mm->map_count++;
1373 return 0;
1374
1375err_vmi_preallocate:
1376 vm_area_free(new);
1377err_vma_dup:
1378 kmem_cache_free(vm_region_jar, region);
1379 return -ENOMEM;
1380}
1381
1382/*
1383 * shrink a VMA by removing the specified chunk from either the beginning or
1384 * the end
1385 */
1386static int vmi_shrink_vma(struct vma_iterator *vmi,
1387 struct vm_area_struct *vma,
1388 unsigned long from, unsigned long to)
1389{
1390 struct vm_region *region;
1391
1392 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1393 * and list */
1394 if (from > vma->vm_start) {
1395 if (vma_iter_clear_gfp(vmi, from, vma->vm_end, GFP_KERNEL))
1396 return -ENOMEM;
1397 vma->vm_end = from;
1398 } else {
1399 if (vma_iter_clear_gfp(vmi, vma->vm_start, to, GFP_KERNEL))
1400 return -ENOMEM;
1401 vma->vm_start = to;
1402 }
1403
1404 /* cut the backing region down to size */
1405 region = vma->vm_region;
1406 BUG_ON(region->vm_usage != 1);
1407
1408 down_write(&nommu_region_sem);
1409 delete_nommu_region(region);
1410 if (from > region->vm_start) {
1411 to = region->vm_top;
1412 region->vm_top = region->vm_end = from;
1413 } else {
1414 region->vm_start = to;
1415 }
1416 add_nommu_region(region);
1417 up_write(&nommu_region_sem);
1418
1419 free_page_series(from, to);
1420 return 0;
1421}
1422
1423/*
1424 * release a mapping
1425 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1426 * VMA, though it need not cover the whole VMA
1427 */
1428int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
1429{
1430 VMA_ITERATOR(vmi, mm, start);
1431 struct vm_area_struct *vma;
1432 unsigned long end;
1433 int ret = 0;
1434
1435 len = PAGE_ALIGN(len);
1436 if (len == 0)
1437 return -EINVAL;
1438
1439 end = start + len;
1440
1441 /* find the first potentially overlapping VMA */
1442 vma = vma_find(&vmi, end);
1443 if (!vma) {
1444 static int limit;
1445 if (limit < 5) {
1446 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1447 current->pid, current->comm,
1448 start, start + len - 1);
1449 limit++;
1450 }
1451 return -EINVAL;
1452 }
1453
1454 /* we're allowed to split an anonymous VMA but not a file-backed one */
1455 if (vma->vm_file) {
1456 do {
1457 if (start > vma->vm_start)
1458 return -EINVAL;
1459 if (end == vma->vm_end)
1460 goto erase_whole_vma;
1461 vma = vma_find(&vmi, end);
1462 } while (vma);
1463 return -EINVAL;
1464 } else {
1465 /* the chunk must be a subset of the VMA found */
1466 if (start == vma->vm_start && end == vma->vm_end)
1467 goto erase_whole_vma;
1468 if (start < vma->vm_start || end > vma->vm_end)
1469 return -EINVAL;
1470 if (offset_in_page(start))
1471 return -EINVAL;
1472 if (end != vma->vm_end && offset_in_page(end))
1473 return -EINVAL;
1474 if (start != vma->vm_start && end != vma->vm_end) {
1475 ret = split_vma(&vmi, vma, start, 1);
1476 if (ret < 0)
1477 return ret;
1478 }
1479 return vmi_shrink_vma(&vmi, vma, start, end);
1480 }
1481
1482erase_whole_vma:
1483 if (delete_vma_from_mm(vma))
1484 ret = -ENOMEM;
1485 else
1486 delete_vma(mm, vma);
1487 return ret;
1488}
1489
1490int vm_munmap(unsigned long addr, size_t len)
1491{
1492 struct mm_struct *mm = current->mm;
1493 int ret;
1494
1495 mmap_write_lock(mm);
1496 ret = do_munmap(mm, addr, len, NULL);
1497 mmap_write_unlock(mm);
1498 return ret;
1499}
1500EXPORT_SYMBOL(vm_munmap);
1501
1502SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1503{
1504 return vm_munmap(addr, len);
1505}
1506
1507/*
1508 * release all the mappings made in a process's VM space
1509 */
1510void exit_mmap(struct mm_struct *mm)
1511{
1512 VMA_ITERATOR(vmi, mm, 0);
1513 struct vm_area_struct *vma;
1514
1515 if (!mm)
1516 return;
1517
1518 mm->total_vm = 0;
1519
1520 /*
1521 * Lock the mm to avoid assert complaining even though this is the only
1522 * user of the mm
1523 */
1524 mmap_write_lock(mm);
1525 for_each_vma(vmi, vma) {
1526 cleanup_vma_from_mm(vma);
1527 delete_vma(mm, vma);
1528 cond_resched();
1529 }
1530 __mt_destroy(&mm->mm_mt);
1531 mmap_write_unlock(mm);
1532}
1533
1534/*
1535 * expand (or shrink) an existing mapping, potentially moving it at the same
1536 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1537 *
1538 * under NOMMU conditions, we only permit changing a mapping's size, and only
1539 * as long as it stays within the region allocated by do_mmap_private() and the
1540 * block is not shareable
1541 *
1542 * MREMAP_FIXED is not supported under NOMMU conditions
1543 */
1544static unsigned long do_mremap(unsigned long addr,
1545 unsigned long old_len, unsigned long new_len,
1546 unsigned long flags, unsigned long new_addr)
1547{
1548 struct vm_area_struct *vma;
1549
1550 /* insanity checks first */
1551 old_len = PAGE_ALIGN(old_len);
1552 new_len = PAGE_ALIGN(new_len);
1553 if (old_len == 0 || new_len == 0)
1554 return (unsigned long) -EINVAL;
1555
1556 if (offset_in_page(addr))
1557 return -EINVAL;
1558
1559 if (flags & MREMAP_FIXED && new_addr != addr)
1560 return (unsigned long) -EINVAL;
1561
1562 vma = find_vma_exact(current->mm, addr, old_len);
1563 if (!vma)
1564 return (unsigned long) -EINVAL;
1565
1566 if (vma->vm_end != vma->vm_start + old_len)
1567 return (unsigned long) -EFAULT;
1568
1569 if (is_nommu_shared_mapping(vma->vm_flags))
1570 return (unsigned long) -EPERM;
1571
1572 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1573 return (unsigned long) -ENOMEM;
1574
1575 /* all checks complete - do it */
1576 vma->vm_end = vma->vm_start + new_len;
1577 return vma->vm_start;
1578}
1579
1580SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1581 unsigned long, new_len, unsigned long, flags,
1582 unsigned long, new_addr)
1583{
1584 unsigned long ret;
1585
1586 mmap_write_lock(current->mm);
1587 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1588 mmap_write_unlock(current->mm);
1589 return ret;
1590}
1591
1592struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1593 unsigned int foll_flags)
1594{
1595 return NULL;
1596}
1597
1598int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1599 unsigned long pfn, unsigned long size, pgprot_t prot)
1600{
1601 if (addr != (pfn << PAGE_SHIFT))
1602 return -EINVAL;
1603
1604 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
1605 return 0;
1606}
1607EXPORT_SYMBOL(remap_pfn_range);
1608
1609int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1610{
1611 unsigned long pfn = start >> PAGE_SHIFT;
1612 unsigned long vm_len = vma->vm_end - vma->vm_start;
1613
1614 pfn += vma->vm_pgoff;
1615 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1616}
1617EXPORT_SYMBOL(vm_iomap_memory);
1618
1619int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1620 unsigned long pgoff)
1621{
1622 unsigned int size = vma->vm_end - vma->vm_start;
1623
1624 if (!(vma->vm_flags & VM_USERMAP))
1625 return -EINVAL;
1626
1627 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1628 vma->vm_end = vma->vm_start + size;
1629
1630 return 0;
1631}
1632EXPORT_SYMBOL(remap_vmalloc_range);
1633
1634vm_fault_t filemap_fault(struct vm_fault *vmf)
1635{
1636 BUG();
1637 return 0;
1638}
1639EXPORT_SYMBOL(filemap_fault);
1640
1641vm_fault_t filemap_map_pages(struct vm_fault *vmf,
1642 pgoff_t start_pgoff, pgoff_t end_pgoff)
1643{
1644 BUG();
1645 return 0;
1646}
1647EXPORT_SYMBOL(filemap_map_pages);
1648
1649static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
1650 void *buf, int len, unsigned int gup_flags)
1651{
1652 struct vm_area_struct *vma;
1653 int write = gup_flags & FOLL_WRITE;
1654
1655 if (mmap_read_lock_killable(mm))
1656 return 0;
1657
1658 /* the access must start within one of the target process's mappings */
1659 vma = find_vma(mm, addr);
1660 if (vma) {
1661 /* don't overrun this mapping */
1662 if (addr + len >= vma->vm_end)
1663 len = vma->vm_end - addr;
1664
1665 /* only read or write mappings where it is permitted */
1666 if (write && vma->vm_flags & VM_MAYWRITE)
1667 copy_to_user_page(vma, NULL, addr,
1668 (void *) addr, buf, len);
1669 else if (!write && vma->vm_flags & VM_MAYREAD)
1670 copy_from_user_page(vma, NULL, addr,
1671 buf, (void *) addr, len);
1672 else
1673 len = 0;
1674 } else {
1675 len = 0;
1676 }
1677
1678 mmap_read_unlock(mm);
1679
1680 return len;
1681}
1682
1683/**
1684 * access_remote_vm - access another process' address space
1685 * @mm: the mm_struct of the target address space
1686 * @addr: start address to access
1687 * @buf: source or destination buffer
1688 * @len: number of bytes to transfer
1689 * @gup_flags: flags modifying lookup behaviour
1690 *
1691 * The caller must hold a reference on @mm.
1692 */
1693int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1694 void *buf, int len, unsigned int gup_flags)
1695{
1696 return __access_remote_vm(mm, addr, buf, len, gup_flags);
1697}
1698
1699/*
1700 * Access another process' address space.
1701 * - source/target buffer must be kernel space
1702 */
1703int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
1704 unsigned int gup_flags)
1705{
1706 struct mm_struct *mm;
1707
1708 if (addr + len < addr)
1709 return 0;
1710
1711 mm = get_task_mm(tsk);
1712 if (!mm)
1713 return 0;
1714
1715 len = __access_remote_vm(mm, addr, buf, len, gup_flags);
1716
1717 mmput(mm);
1718 return len;
1719}
1720EXPORT_SYMBOL_GPL(access_process_vm);
1721
1722/**
1723 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1724 * @inode: The inode to check
1725 * @size: The current filesize of the inode
1726 * @newsize: The proposed filesize of the inode
1727 *
1728 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1729 * make sure that any outstanding VMAs aren't broken and then shrink the
1730 * vm_regions that extend beyond so that do_mmap() doesn't
1731 * automatically grant mappings that are too large.
1732 */
1733int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1734 size_t newsize)
1735{
1736 struct vm_area_struct *vma;
1737 struct vm_region *region;
1738 pgoff_t low, high;
1739 size_t r_size, r_top;
1740
1741 low = newsize >> PAGE_SHIFT;
1742 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1743
1744 down_write(&nommu_region_sem);
1745 i_mmap_lock_read(inode->i_mapping);
1746
1747 /* search for VMAs that fall within the dead zone */
1748 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1749 /* found one - only interested if it's shared out of the page
1750 * cache */
1751 if (vma->vm_flags & VM_SHARED) {
1752 i_mmap_unlock_read(inode->i_mapping);
1753 up_write(&nommu_region_sem);
1754 return -ETXTBSY; /* not quite true, but near enough */
1755 }
1756 }
1757
1758 /* reduce any regions that overlap the dead zone - if in existence,
1759 * these will be pointed to by VMAs that don't overlap the dead zone
1760 *
1761 * we don't check for any regions that start beyond the EOF as there
1762 * shouldn't be any
1763 */
1764 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1765 if (!(vma->vm_flags & VM_SHARED))
1766 continue;
1767
1768 region = vma->vm_region;
1769 r_size = region->vm_top - region->vm_start;
1770 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1771
1772 if (r_top > newsize) {
1773 region->vm_top -= r_top - newsize;
1774 if (region->vm_end > region->vm_top)
1775 region->vm_end = region->vm_top;
1776 }
1777 }
1778
1779 i_mmap_unlock_read(inode->i_mapping);
1780 up_write(&nommu_region_sem);
1781 return 0;
1782}
1783
1784/*
1785 * Initialise sysctl_user_reserve_kbytes.
1786 *
1787 * This is intended to prevent a user from starting a single memory hogging
1788 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1789 * mode.
1790 *
1791 * The default value is min(3% of free memory, 128MB)
1792 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1793 */
1794static int __meminit init_user_reserve(void)
1795{
1796 unsigned long free_kbytes;
1797
1798 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1799
1800 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1801 return 0;
1802}
1803subsys_initcall(init_user_reserve);
1804
1805/*
1806 * Initialise sysctl_admin_reserve_kbytes.
1807 *
1808 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1809 * to log in and kill a memory hogging process.
1810 *
1811 * Systems with more than 256MB will reserve 8MB, enough to recover
1812 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1813 * only reserve 3% of free pages by default.
1814 */
1815static int __meminit init_admin_reserve(void)
1816{
1817 unsigned long free_kbytes;
1818
1819 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1820
1821 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1822 return 0;
1823}
1824subsys_initcall(init_admin_reserve);
1/*
2 * linux/mm/nommu.c
3 *
4 * Replacement code for mm functions to support CPU's that don't
5 * have any form of memory management unit (thus no virtual memory).
6 *
7 * See Documentation/nommu-mmap.txt
8 *
9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
13 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
14 */
15
16#include <linux/module.h>
17#include <linux/mm.h>
18#include <linux/mman.h>
19#include <linux/swap.h>
20#include <linux/file.h>
21#include <linux/highmem.h>
22#include <linux/pagemap.h>
23#include <linux/slab.h>
24#include <linux/vmalloc.h>
25#include <linux/blkdev.h>
26#include <linux/backing-dev.h>
27#include <linux/mount.h>
28#include <linux/personality.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/audit.h>
32
33#include <asm/uaccess.h>
34#include <asm/tlb.h>
35#include <asm/tlbflush.h>
36#include <asm/mmu_context.h>
37#include "internal.h"
38
39#if 0
40#define kenter(FMT, ...) \
41 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
42#define kleave(FMT, ...) \
43 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
44#define kdebug(FMT, ...) \
45 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
46#else
47#define kenter(FMT, ...) \
48 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
49#define kleave(FMT, ...) \
50 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
51#define kdebug(FMT, ...) \
52 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
53#endif
54
55void *high_memory;
56struct page *mem_map;
57unsigned long max_mapnr;
58unsigned long num_physpages;
59unsigned long highest_memmap_pfn;
60struct percpu_counter vm_committed_as;
61int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
62int sysctl_overcommit_ratio = 50; /* default is 50% */
63int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
64int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
65int heap_stack_gap = 0;
66
67atomic_long_t mmap_pages_allocated;
68
69EXPORT_SYMBOL(mem_map);
70EXPORT_SYMBOL(num_physpages);
71
72/* list of mapped, potentially shareable regions */
73static struct kmem_cache *vm_region_jar;
74struct rb_root nommu_region_tree = RB_ROOT;
75DECLARE_RWSEM(nommu_region_sem);
76
77const struct vm_operations_struct generic_file_vm_ops = {
78};
79
80/*
81 * Return the total memory allocated for this pointer, not
82 * just what the caller asked for.
83 *
84 * Doesn't have to be accurate, i.e. may have races.
85 */
86unsigned int kobjsize(const void *objp)
87{
88 struct page *page;
89
90 /*
91 * If the object we have should not have ksize performed on it,
92 * return size of 0
93 */
94 if (!objp || !virt_addr_valid(objp))
95 return 0;
96
97 page = virt_to_head_page(objp);
98
99 /*
100 * If the allocator sets PageSlab, we know the pointer came from
101 * kmalloc().
102 */
103 if (PageSlab(page))
104 return ksize(objp);
105
106 /*
107 * If it's not a compound page, see if we have a matching VMA
108 * region. This test is intentionally done in reverse order,
109 * so if there's no VMA, we still fall through and hand back
110 * PAGE_SIZE for 0-order pages.
111 */
112 if (!PageCompound(page)) {
113 struct vm_area_struct *vma;
114
115 vma = find_vma(current->mm, (unsigned long)objp);
116 if (vma)
117 return vma->vm_end - vma->vm_start;
118 }
119
120 /*
121 * The ksize() function is only guaranteed to work for pointers
122 * returned by kmalloc(). So handle arbitrary pointers here.
123 */
124 return PAGE_SIZE << compound_order(page);
125}
126
127int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
128 unsigned long start, int nr_pages, unsigned int foll_flags,
129 struct page **pages, struct vm_area_struct **vmas,
130 int *retry)
131{
132 struct vm_area_struct *vma;
133 unsigned long vm_flags;
134 int i;
135
136 /* calculate required read or write permissions.
137 * If FOLL_FORCE is set, we only require the "MAY" flags.
138 */
139 vm_flags = (foll_flags & FOLL_WRITE) ?
140 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
141 vm_flags &= (foll_flags & FOLL_FORCE) ?
142 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
143
144 for (i = 0; i < nr_pages; i++) {
145 vma = find_vma(mm, start);
146 if (!vma)
147 goto finish_or_fault;
148
149 /* protect what we can, including chardevs */
150 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
151 !(vm_flags & vma->vm_flags))
152 goto finish_or_fault;
153
154 if (pages) {
155 pages[i] = virt_to_page(start);
156 if (pages[i])
157 page_cache_get(pages[i]);
158 }
159 if (vmas)
160 vmas[i] = vma;
161 start = (start + PAGE_SIZE) & PAGE_MASK;
162 }
163
164 return i;
165
166finish_or_fault:
167 return i ? : -EFAULT;
168}
169
170/*
171 * get a list of pages in an address range belonging to the specified process
172 * and indicate the VMA that covers each page
173 * - this is potentially dodgy as we may end incrementing the page count of a
174 * slab page or a secondary page from a compound page
175 * - don't permit access to VMAs that don't support it, such as I/O mappings
176 */
177int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
178 unsigned long start, int nr_pages, int write, int force,
179 struct page **pages, struct vm_area_struct **vmas)
180{
181 int flags = 0;
182
183 if (write)
184 flags |= FOLL_WRITE;
185 if (force)
186 flags |= FOLL_FORCE;
187
188 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
189 NULL);
190}
191EXPORT_SYMBOL(get_user_pages);
192
193/**
194 * follow_pfn - look up PFN at a user virtual address
195 * @vma: memory mapping
196 * @address: user virtual address
197 * @pfn: location to store found PFN
198 *
199 * Only IO mappings and raw PFN mappings are allowed.
200 *
201 * Returns zero and the pfn at @pfn on success, -ve otherwise.
202 */
203int follow_pfn(struct vm_area_struct *vma, unsigned long address,
204 unsigned long *pfn)
205{
206 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
207 return -EINVAL;
208
209 *pfn = address >> PAGE_SHIFT;
210 return 0;
211}
212EXPORT_SYMBOL(follow_pfn);
213
214DEFINE_RWLOCK(vmlist_lock);
215struct vm_struct *vmlist;
216
217void vfree(const void *addr)
218{
219 kfree(addr);
220}
221EXPORT_SYMBOL(vfree);
222
223void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
224{
225 /*
226 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
227 * returns only a logical address.
228 */
229 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
230}
231EXPORT_SYMBOL(__vmalloc);
232
233void *vmalloc_user(unsigned long size)
234{
235 void *ret;
236
237 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
238 PAGE_KERNEL);
239 if (ret) {
240 struct vm_area_struct *vma;
241
242 down_write(¤t->mm->mmap_sem);
243 vma = find_vma(current->mm, (unsigned long)ret);
244 if (vma)
245 vma->vm_flags |= VM_USERMAP;
246 up_write(¤t->mm->mmap_sem);
247 }
248
249 return ret;
250}
251EXPORT_SYMBOL(vmalloc_user);
252
253struct page *vmalloc_to_page(const void *addr)
254{
255 return virt_to_page(addr);
256}
257EXPORT_SYMBOL(vmalloc_to_page);
258
259unsigned long vmalloc_to_pfn(const void *addr)
260{
261 return page_to_pfn(virt_to_page(addr));
262}
263EXPORT_SYMBOL(vmalloc_to_pfn);
264
265long vread(char *buf, char *addr, unsigned long count)
266{
267 memcpy(buf, addr, count);
268 return count;
269}
270
271long vwrite(char *buf, char *addr, unsigned long count)
272{
273 /* Don't allow overflow */
274 if ((unsigned long) addr + count < count)
275 count = -(unsigned long) addr;
276
277 memcpy(addr, buf, count);
278 return(count);
279}
280
281/*
282 * vmalloc - allocate virtually continguos memory
283 *
284 * @size: allocation size
285 *
286 * Allocate enough pages to cover @size from the page level
287 * allocator and map them into continguos kernel virtual space.
288 *
289 * For tight control over page level allocator and protection flags
290 * use __vmalloc() instead.
291 */
292void *vmalloc(unsigned long size)
293{
294 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
295}
296EXPORT_SYMBOL(vmalloc);
297
298/*
299 * vzalloc - allocate virtually continguos memory with zero fill
300 *
301 * @size: allocation size
302 *
303 * Allocate enough pages to cover @size from the page level
304 * allocator and map them into continguos kernel virtual space.
305 * The memory allocated is set to zero.
306 *
307 * For tight control over page level allocator and protection flags
308 * use __vmalloc() instead.
309 */
310void *vzalloc(unsigned long size)
311{
312 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
313 PAGE_KERNEL);
314}
315EXPORT_SYMBOL(vzalloc);
316
317/**
318 * vmalloc_node - allocate memory on a specific node
319 * @size: allocation size
320 * @node: numa node
321 *
322 * Allocate enough pages to cover @size from the page level
323 * allocator and map them into contiguous kernel virtual space.
324 *
325 * For tight control over page level allocator and protection flags
326 * use __vmalloc() instead.
327 */
328void *vmalloc_node(unsigned long size, int node)
329{
330 return vmalloc(size);
331}
332EXPORT_SYMBOL(vmalloc_node);
333
334/**
335 * vzalloc_node - allocate memory on a specific node with zero fill
336 * @size: allocation size
337 * @node: numa node
338 *
339 * Allocate enough pages to cover @size from the page level
340 * allocator and map them into contiguous kernel virtual space.
341 * The memory allocated is set to zero.
342 *
343 * For tight control over page level allocator and protection flags
344 * use __vmalloc() instead.
345 */
346void *vzalloc_node(unsigned long size, int node)
347{
348 return vzalloc(size);
349}
350EXPORT_SYMBOL(vzalloc_node);
351
352#ifndef PAGE_KERNEL_EXEC
353# define PAGE_KERNEL_EXEC PAGE_KERNEL
354#endif
355
356/**
357 * vmalloc_exec - allocate virtually contiguous, executable memory
358 * @size: allocation size
359 *
360 * Kernel-internal function to allocate enough pages to cover @size
361 * the page level allocator and map them into contiguous and
362 * executable kernel virtual space.
363 *
364 * For tight control over page level allocator and protection flags
365 * use __vmalloc() instead.
366 */
367
368void *vmalloc_exec(unsigned long size)
369{
370 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
371}
372
373/**
374 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
375 * @size: allocation size
376 *
377 * Allocate enough 32bit PA addressable pages to cover @size from the
378 * page level allocator and map them into continguos kernel virtual space.
379 */
380void *vmalloc_32(unsigned long size)
381{
382 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
383}
384EXPORT_SYMBOL(vmalloc_32);
385
386/**
387 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
388 * @size: allocation size
389 *
390 * The resulting memory area is 32bit addressable and zeroed so it can be
391 * mapped to userspace without leaking data.
392 *
393 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
394 * remap_vmalloc_range() are permissible.
395 */
396void *vmalloc_32_user(unsigned long size)
397{
398 /*
399 * We'll have to sort out the ZONE_DMA bits for 64-bit,
400 * but for now this can simply use vmalloc_user() directly.
401 */
402 return vmalloc_user(size);
403}
404EXPORT_SYMBOL(vmalloc_32_user);
405
406void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
407{
408 BUG();
409 return NULL;
410}
411EXPORT_SYMBOL(vmap);
412
413void vunmap(const void *addr)
414{
415 BUG();
416}
417EXPORT_SYMBOL(vunmap);
418
419void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
420{
421 BUG();
422 return NULL;
423}
424EXPORT_SYMBOL(vm_map_ram);
425
426void vm_unmap_ram(const void *mem, unsigned int count)
427{
428 BUG();
429}
430EXPORT_SYMBOL(vm_unmap_ram);
431
432void vm_unmap_aliases(void)
433{
434}
435EXPORT_SYMBOL_GPL(vm_unmap_aliases);
436
437/*
438 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
439 * have one.
440 */
441void __attribute__((weak)) vmalloc_sync_all(void)
442{
443}
444
445/**
446 * alloc_vm_area - allocate a range of kernel address space
447 * @size: size of the area
448 *
449 * Returns: NULL on failure, vm_struct on success
450 *
451 * This function reserves a range of kernel address space, and
452 * allocates pagetables to map that range. No actual mappings
453 * are created. If the kernel address space is not shared
454 * between processes, it syncs the pagetable across all
455 * processes.
456 */
457struct vm_struct *alloc_vm_area(size_t size)
458{
459 BUG();
460 return NULL;
461}
462EXPORT_SYMBOL_GPL(alloc_vm_area);
463
464void free_vm_area(struct vm_struct *area)
465{
466 BUG();
467}
468EXPORT_SYMBOL_GPL(free_vm_area);
469
470int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
471 struct page *page)
472{
473 return -EINVAL;
474}
475EXPORT_SYMBOL(vm_insert_page);
476
477/*
478 * sys_brk() for the most part doesn't need the global kernel
479 * lock, except when an application is doing something nasty
480 * like trying to un-brk an area that has already been mapped
481 * to a regular file. in this case, the unmapping will need
482 * to invoke file system routines that need the global lock.
483 */
484SYSCALL_DEFINE1(brk, unsigned long, brk)
485{
486 struct mm_struct *mm = current->mm;
487
488 if (brk < mm->start_brk || brk > mm->context.end_brk)
489 return mm->brk;
490
491 if (mm->brk == brk)
492 return mm->brk;
493
494 /*
495 * Always allow shrinking brk
496 */
497 if (brk <= mm->brk) {
498 mm->brk = brk;
499 return brk;
500 }
501
502 /*
503 * Ok, looks good - let it rip.
504 */
505 flush_icache_range(mm->brk, brk);
506 return mm->brk = brk;
507}
508
509/*
510 * initialise the VMA and region record slabs
511 */
512void __init mmap_init(void)
513{
514 int ret;
515
516 ret = percpu_counter_init(&vm_committed_as, 0);
517 VM_BUG_ON(ret);
518 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
519}
520
521/*
522 * validate the region tree
523 * - the caller must hold the region lock
524 */
525#ifdef CONFIG_DEBUG_NOMMU_REGIONS
526static noinline void validate_nommu_regions(void)
527{
528 struct vm_region *region, *last;
529 struct rb_node *p, *lastp;
530
531 lastp = rb_first(&nommu_region_tree);
532 if (!lastp)
533 return;
534
535 last = rb_entry(lastp, struct vm_region, vm_rb);
536 BUG_ON(unlikely(last->vm_end <= last->vm_start));
537 BUG_ON(unlikely(last->vm_top < last->vm_end));
538
539 while ((p = rb_next(lastp))) {
540 region = rb_entry(p, struct vm_region, vm_rb);
541 last = rb_entry(lastp, struct vm_region, vm_rb);
542
543 BUG_ON(unlikely(region->vm_end <= region->vm_start));
544 BUG_ON(unlikely(region->vm_top < region->vm_end));
545 BUG_ON(unlikely(region->vm_start < last->vm_top));
546
547 lastp = p;
548 }
549}
550#else
551static void validate_nommu_regions(void)
552{
553}
554#endif
555
556/*
557 * add a region into the global tree
558 */
559static void add_nommu_region(struct vm_region *region)
560{
561 struct vm_region *pregion;
562 struct rb_node **p, *parent;
563
564 validate_nommu_regions();
565
566 parent = NULL;
567 p = &nommu_region_tree.rb_node;
568 while (*p) {
569 parent = *p;
570 pregion = rb_entry(parent, struct vm_region, vm_rb);
571 if (region->vm_start < pregion->vm_start)
572 p = &(*p)->rb_left;
573 else if (region->vm_start > pregion->vm_start)
574 p = &(*p)->rb_right;
575 else if (pregion == region)
576 return;
577 else
578 BUG();
579 }
580
581 rb_link_node(®ion->vm_rb, parent, p);
582 rb_insert_color(®ion->vm_rb, &nommu_region_tree);
583
584 validate_nommu_regions();
585}
586
587/*
588 * delete a region from the global tree
589 */
590static void delete_nommu_region(struct vm_region *region)
591{
592 BUG_ON(!nommu_region_tree.rb_node);
593
594 validate_nommu_regions();
595 rb_erase(®ion->vm_rb, &nommu_region_tree);
596 validate_nommu_regions();
597}
598
599/*
600 * free a contiguous series of pages
601 */
602static void free_page_series(unsigned long from, unsigned long to)
603{
604 for (; from < to; from += PAGE_SIZE) {
605 struct page *page = virt_to_page(from);
606
607 kdebug("- free %lx", from);
608 atomic_long_dec(&mmap_pages_allocated);
609 if (page_count(page) != 1)
610 kdebug("free page %p: refcount not one: %d",
611 page, page_count(page));
612 put_page(page);
613 }
614}
615
616/*
617 * release a reference to a region
618 * - the caller must hold the region semaphore for writing, which this releases
619 * - the region may not have been added to the tree yet, in which case vm_top
620 * will equal vm_start
621 */
622static void __put_nommu_region(struct vm_region *region)
623 __releases(nommu_region_sem)
624{
625 kenter("%p{%d}", region, region->vm_usage);
626
627 BUG_ON(!nommu_region_tree.rb_node);
628
629 if (--region->vm_usage == 0) {
630 if (region->vm_top > region->vm_start)
631 delete_nommu_region(region);
632 up_write(&nommu_region_sem);
633
634 if (region->vm_file)
635 fput(region->vm_file);
636
637 /* IO memory and memory shared directly out of the pagecache
638 * from ramfs/tmpfs mustn't be released here */
639 if (region->vm_flags & VM_MAPPED_COPY) {
640 kdebug("free series");
641 free_page_series(region->vm_start, region->vm_top);
642 }
643 kmem_cache_free(vm_region_jar, region);
644 } else {
645 up_write(&nommu_region_sem);
646 }
647}
648
649/*
650 * release a reference to a region
651 */
652static void put_nommu_region(struct vm_region *region)
653{
654 down_write(&nommu_region_sem);
655 __put_nommu_region(region);
656}
657
658/*
659 * update protection on a vma
660 */
661static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
662{
663#ifdef CONFIG_MPU
664 struct mm_struct *mm = vma->vm_mm;
665 long start = vma->vm_start & PAGE_MASK;
666 while (start < vma->vm_end) {
667 protect_page(mm, start, flags);
668 start += PAGE_SIZE;
669 }
670 update_protections(mm);
671#endif
672}
673
674/*
675 * add a VMA into a process's mm_struct in the appropriate place in the list
676 * and tree and add to the address space's page tree also if not an anonymous
677 * page
678 * - should be called with mm->mmap_sem held writelocked
679 */
680static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
681{
682 struct vm_area_struct *pvma, *prev;
683 struct address_space *mapping;
684 struct rb_node **p, *parent, *rb_prev;
685
686 kenter(",%p", vma);
687
688 BUG_ON(!vma->vm_region);
689
690 mm->map_count++;
691 vma->vm_mm = mm;
692
693 protect_vma(vma, vma->vm_flags);
694
695 /* add the VMA to the mapping */
696 if (vma->vm_file) {
697 mapping = vma->vm_file->f_mapping;
698
699 flush_dcache_mmap_lock(mapping);
700 vma_prio_tree_insert(vma, &mapping->i_mmap);
701 flush_dcache_mmap_unlock(mapping);
702 }
703
704 /* add the VMA to the tree */
705 parent = rb_prev = NULL;
706 p = &mm->mm_rb.rb_node;
707 while (*p) {
708 parent = *p;
709 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
710
711 /* sort by: start addr, end addr, VMA struct addr in that order
712 * (the latter is necessary as we may get identical VMAs) */
713 if (vma->vm_start < pvma->vm_start)
714 p = &(*p)->rb_left;
715 else if (vma->vm_start > pvma->vm_start) {
716 rb_prev = parent;
717 p = &(*p)->rb_right;
718 } else if (vma->vm_end < pvma->vm_end)
719 p = &(*p)->rb_left;
720 else if (vma->vm_end > pvma->vm_end) {
721 rb_prev = parent;
722 p = &(*p)->rb_right;
723 } else if (vma < pvma)
724 p = &(*p)->rb_left;
725 else if (vma > pvma) {
726 rb_prev = parent;
727 p = &(*p)->rb_right;
728 } else
729 BUG();
730 }
731
732 rb_link_node(&vma->vm_rb, parent, p);
733 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
734
735 /* add VMA to the VMA list also */
736 prev = NULL;
737 if (rb_prev)
738 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
739
740 __vma_link_list(mm, vma, prev, parent);
741}
742
743/*
744 * delete a VMA from its owning mm_struct and address space
745 */
746static void delete_vma_from_mm(struct vm_area_struct *vma)
747{
748 struct address_space *mapping;
749 struct mm_struct *mm = vma->vm_mm;
750
751 kenter("%p", vma);
752
753 protect_vma(vma, 0);
754
755 mm->map_count--;
756 if (mm->mmap_cache == vma)
757 mm->mmap_cache = NULL;
758
759 /* remove the VMA from the mapping */
760 if (vma->vm_file) {
761 mapping = vma->vm_file->f_mapping;
762
763 flush_dcache_mmap_lock(mapping);
764 vma_prio_tree_remove(vma, &mapping->i_mmap);
765 flush_dcache_mmap_unlock(mapping);
766 }
767
768 /* remove from the MM's tree and list */
769 rb_erase(&vma->vm_rb, &mm->mm_rb);
770
771 if (vma->vm_prev)
772 vma->vm_prev->vm_next = vma->vm_next;
773 else
774 mm->mmap = vma->vm_next;
775
776 if (vma->vm_next)
777 vma->vm_next->vm_prev = vma->vm_prev;
778
779 vma->vm_mm = NULL;
780}
781
782/*
783 * destroy a VMA record
784 */
785static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
786{
787 kenter("%p", vma);
788 if (vma->vm_ops && vma->vm_ops->close)
789 vma->vm_ops->close(vma);
790 if (vma->vm_file) {
791 fput(vma->vm_file);
792 if (vma->vm_flags & VM_EXECUTABLE)
793 removed_exe_file_vma(mm);
794 }
795 put_nommu_region(vma->vm_region);
796 kmem_cache_free(vm_area_cachep, vma);
797}
798
799/*
800 * look up the first VMA in which addr resides, NULL if none
801 * - should be called with mm->mmap_sem at least held readlocked
802 */
803struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
804{
805 struct vm_area_struct *vma;
806
807 /* check the cache first */
808 vma = mm->mmap_cache;
809 if (vma && vma->vm_start <= addr && vma->vm_end > addr)
810 return vma;
811
812 /* trawl the list (there may be multiple mappings in which addr
813 * resides) */
814 for (vma = mm->mmap; vma; vma = vma->vm_next) {
815 if (vma->vm_start > addr)
816 return NULL;
817 if (vma->vm_end > addr) {
818 mm->mmap_cache = vma;
819 return vma;
820 }
821 }
822
823 return NULL;
824}
825EXPORT_SYMBOL(find_vma);
826
827/*
828 * find a VMA
829 * - we don't extend stack VMAs under NOMMU conditions
830 */
831struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
832{
833 return find_vma(mm, addr);
834}
835
836/*
837 * expand a stack to a given address
838 * - not supported under NOMMU conditions
839 */
840int expand_stack(struct vm_area_struct *vma, unsigned long address)
841{
842 return -ENOMEM;
843}
844
845/*
846 * look up the first VMA exactly that exactly matches addr
847 * - should be called with mm->mmap_sem at least held readlocked
848 */
849static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
850 unsigned long addr,
851 unsigned long len)
852{
853 struct vm_area_struct *vma;
854 unsigned long end = addr + len;
855
856 /* check the cache first */
857 vma = mm->mmap_cache;
858 if (vma && vma->vm_start == addr && vma->vm_end == end)
859 return vma;
860
861 /* trawl the list (there may be multiple mappings in which addr
862 * resides) */
863 for (vma = mm->mmap; vma; vma = vma->vm_next) {
864 if (vma->vm_start < addr)
865 continue;
866 if (vma->vm_start > addr)
867 return NULL;
868 if (vma->vm_end == end) {
869 mm->mmap_cache = vma;
870 return vma;
871 }
872 }
873
874 return NULL;
875}
876
877/*
878 * determine whether a mapping should be permitted and, if so, what sort of
879 * mapping we're capable of supporting
880 */
881static int validate_mmap_request(struct file *file,
882 unsigned long addr,
883 unsigned long len,
884 unsigned long prot,
885 unsigned long flags,
886 unsigned long pgoff,
887 unsigned long *_capabilities)
888{
889 unsigned long capabilities, rlen;
890 unsigned long reqprot = prot;
891 int ret;
892
893 /* do the simple checks first */
894 if (flags & MAP_FIXED) {
895 printk(KERN_DEBUG
896 "%d: Can't do fixed-address/overlay mmap of RAM\n",
897 current->pid);
898 return -EINVAL;
899 }
900
901 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
902 (flags & MAP_TYPE) != MAP_SHARED)
903 return -EINVAL;
904
905 if (!len)
906 return -EINVAL;
907
908 /* Careful about overflows.. */
909 rlen = PAGE_ALIGN(len);
910 if (!rlen || rlen > TASK_SIZE)
911 return -ENOMEM;
912
913 /* offset overflow? */
914 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
915 return -EOVERFLOW;
916
917 if (file) {
918 /* validate file mapping requests */
919 struct address_space *mapping;
920
921 /* files must support mmap */
922 if (!file->f_op || !file->f_op->mmap)
923 return -ENODEV;
924
925 /* work out if what we've got could possibly be shared
926 * - we support chardevs that provide their own "memory"
927 * - we support files/blockdevs that are memory backed
928 */
929 mapping = file->f_mapping;
930 if (!mapping)
931 mapping = file->f_path.dentry->d_inode->i_mapping;
932
933 capabilities = 0;
934 if (mapping && mapping->backing_dev_info)
935 capabilities = mapping->backing_dev_info->capabilities;
936
937 if (!capabilities) {
938 /* no explicit capabilities set, so assume some
939 * defaults */
940 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
941 case S_IFREG:
942 case S_IFBLK:
943 capabilities = BDI_CAP_MAP_COPY;
944 break;
945
946 case S_IFCHR:
947 capabilities =
948 BDI_CAP_MAP_DIRECT |
949 BDI_CAP_READ_MAP |
950 BDI_CAP_WRITE_MAP;
951 break;
952
953 default:
954 return -EINVAL;
955 }
956 }
957
958 /* eliminate any capabilities that we can't support on this
959 * device */
960 if (!file->f_op->get_unmapped_area)
961 capabilities &= ~BDI_CAP_MAP_DIRECT;
962 if (!file->f_op->read)
963 capabilities &= ~BDI_CAP_MAP_COPY;
964
965 /* The file shall have been opened with read permission. */
966 if (!(file->f_mode & FMODE_READ))
967 return -EACCES;
968
969 if (flags & MAP_SHARED) {
970 /* do checks for writing, appending and locking */
971 if ((prot & PROT_WRITE) &&
972 !(file->f_mode & FMODE_WRITE))
973 return -EACCES;
974
975 if (IS_APPEND(file->f_path.dentry->d_inode) &&
976 (file->f_mode & FMODE_WRITE))
977 return -EACCES;
978
979 if (locks_verify_locked(file->f_path.dentry->d_inode))
980 return -EAGAIN;
981
982 if (!(capabilities & BDI_CAP_MAP_DIRECT))
983 return -ENODEV;
984
985 /* we mustn't privatise shared mappings */
986 capabilities &= ~BDI_CAP_MAP_COPY;
987 }
988 else {
989 /* we're going to read the file into private memory we
990 * allocate */
991 if (!(capabilities & BDI_CAP_MAP_COPY))
992 return -ENODEV;
993
994 /* we don't permit a private writable mapping to be
995 * shared with the backing device */
996 if (prot & PROT_WRITE)
997 capabilities &= ~BDI_CAP_MAP_DIRECT;
998 }
999
1000 if (capabilities & BDI_CAP_MAP_DIRECT) {
1001 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
1002 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1003 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
1004 ) {
1005 capabilities &= ~BDI_CAP_MAP_DIRECT;
1006 if (flags & MAP_SHARED) {
1007 printk(KERN_WARNING
1008 "MAP_SHARED not completely supported on !MMU\n");
1009 return -EINVAL;
1010 }
1011 }
1012 }
1013
1014 /* handle executable mappings and implied executable
1015 * mappings */
1016 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1017 if (prot & PROT_EXEC)
1018 return -EPERM;
1019 }
1020 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1021 /* handle implication of PROT_EXEC by PROT_READ */
1022 if (current->personality & READ_IMPLIES_EXEC) {
1023 if (capabilities & BDI_CAP_EXEC_MAP)
1024 prot |= PROT_EXEC;
1025 }
1026 }
1027 else if ((prot & PROT_READ) &&
1028 (prot & PROT_EXEC) &&
1029 !(capabilities & BDI_CAP_EXEC_MAP)
1030 ) {
1031 /* backing file is not executable, try to copy */
1032 capabilities &= ~BDI_CAP_MAP_DIRECT;
1033 }
1034 }
1035 else {
1036 /* anonymous mappings are always memory backed and can be
1037 * privately mapped
1038 */
1039 capabilities = BDI_CAP_MAP_COPY;
1040
1041 /* handle PROT_EXEC implication by PROT_READ */
1042 if ((prot & PROT_READ) &&
1043 (current->personality & READ_IMPLIES_EXEC))
1044 prot |= PROT_EXEC;
1045 }
1046
1047 /* allow the security API to have its say */
1048 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1049 if (ret < 0)
1050 return ret;
1051
1052 /* looks okay */
1053 *_capabilities = capabilities;
1054 return 0;
1055}
1056
1057/*
1058 * we've determined that we can make the mapping, now translate what we
1059 * now know into VMA flags
1060 */
1061static unsigned long determine_vm_flags(struct file *file,
1062 unsigned long prot,
1063 unsigned long flags,
1064 unsigned long capabilities)
1065{
1066 unsigned long vm_flags;
1067
1068 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1069 /* vm_flags |= mm->def_flags; */
1070
1071 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1072 /* attempt to share read-only copies of mapped file chunks */
1073 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1074 if (file && !(prot & PROT_WRITE))
1075 vm_flags |= VM_MAYSHARE;
1076 } else {
1077 /* overlay a shareable mapping on the backing device or inode
1078 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1079 * romfs/cramfs */
1080 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1081 if (flags & MAP_SHARED)
1082 vm_flags |= VM_SHARED;
1083 }
1084
1085 /* refuse to let anyone share private mappings with this process if
1086 * it's being traced - otherwise breakpoints set in it may interfere
1087 * with another untraced process
1088 */
1089 if ((flags & MAP_PRIVATE) && current->ptrace)
1090 vm_flags &= ~VM_MAYSHARE;
1091
1092 return vm_flags;
1093}
1094
1095/*
1096 * set up a shared mapping on a file (the driver or filesystem provides and
1097 * pins the storage)
1098 */
1099static int do_mmap_shared_file(struct vm_area_struct *vma)
1100{
1101 int ret;
1102
1103 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1104 if (ret == 0) {
1105 vma->vm_region->vm_top = vma->vm_region->vm_end;
1106 return 0;
1107 }
1108 if (ret != -ENOSYS)
1109 return ret;
1110
1111 /* getting -ENOSYS indicates that direct mmap isn't possible (as
1112 * opposed to tried but failed) so we can only give a suitable error as
1113 * it's not possible to make a private copy if MAP_SHARED was given */
1114 return -ENODEV;
1115}
1116
1117/*
1118 * set up a private mapping or an anonymous shared mapping
1119 */
1120static int do_mmap_private(struct vm_area_struct *vma,
1121 struct vm_region *region,
1122 unsigned long len,
1123 unsigned long capabilities)
1124{
1125 struct page *pages;
1126 unsigned long total, point, n;
1127 void *base;
1128 int ret, order;
1129
1130 /* invoke the file's mapping function so that it can keep track of
1131 * shared mappings on devices or memory
1132 * - VM_MAYSHARE will be set if it may attempt to share
1133 */
1134 if (capabilities & BDI_CAP_MAP_DIRECT) {
1135 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1136 if (ret == 0) {
1137 /* shouldn't return success if we're not sharing */
1138 BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1139 vma->vm_region->vm_top = vma->vm_region->vm_end;
1140 return 0;
1141 }
1142 if (ret != -ENOSYS)
1143 return ret;
1144
1145 /* getting an ENOSYS error indicates that direct mmap isn't
1146 * possible (as opposed to tried but failed) so we'll try to
1147 * make a private copy of the data and map that instead */
1148 }
1149
1150
1151 /* allocate some memory to hold the mapping
1152 * - note that this may not return a page-aligned address if the object
1153 * we're allocating is smaller than a page
1154 */
1155 order = get_order(len);
1156 kdebug("alloc order %d for %lx", order, len);
1157
1158 pages = alloc_pages(GFP_KERNEL, order);
1159 if (!pages)
1160 goto enomem;
1161
1162 total = 1 << order;
1163 atomic_long_add(total, &mmap_pages_allocated);
1164
1165 point = len >> PAGE_SHIFT;
1166
1167 /* we allocated a power-of-2 sized page set, so we may want to trim off
1168 * the excess */
1169 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1170 while (total > point) {
1171 order = ilog2(total - point);
1172 n = 1 << order;
1173 kdebug("shave %lu/%lu @%lu", n, total - point, total);
1174 atomic_long_sub(n, &mmap_pages_allocated);
1175 total -= n;
1176 set_page_refcounted(pages + total);
1177 __free_pages(pages + total, order);
1178 }
1179 }
1180
1181 for (point = 1; point < total; point++)
1182 set_page_refcounted(&pages[point]);
1183
1184 base = page_address(pages);
1185 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1186 region->vm_start = (unsigned long) base;
1187 region->vm_end = region->vm_start + len;
1188 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
1189
1190 vma->vm_start = region->vm_start;
1191 vma->vm_end = region->vm_start + len;
1192
1193 if (vma->vm_file) {
1194 /* read the contents of a file into the copy */
1195 mm_segment_t old_fs;
1196 loff_t fpos;
1197
1198 fpos = vma->vm_pgoff;
1199 fpos <<= PAGE_SHIFT;
1200
1201 old_fs = get_fs();
1202 set_fs(KERNEL_DS);
1203 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1204 set_fs(old_fs);
1205
1206 if (ret < 0)
1207 goto error_free;
1208
1209 /* clear the last little bit */
1210 if (ret < len)
1211 memset(base + ret, 0, len - ret);
1212
1213 }
1214
1215 return 0;
1216
1217error_free:
1218 free_page_series(region->vm_start, region->vm_top);
1219 region->vm_start = vma->vm_start = 0;
1220 region->vm_end = vma->vm_end = 0;
1221 region->vm_top = 0;
1222 return ret;
1223
1224enomem:
1225 printk("Allocation of length %lu from process %d (%s) failed\n",
1226 len, current->pid, current->comm);
1227 show_free_areas(0);
1228 return -ENOMEM;
1229}
1230
1231/*
1232 * handle mapping creation for uClinux
1233 */
1234unsigned long do_mmap_pgoff(struct file *file,
1235 unsigned long addr,
1236 unsigned long len,
1237 unsigned long prot,
1238 unsigned long flags,
1239 unsigned long pgoff)
1240{
1241 struct vm_area_struct *vma;
1242 struct vm_region *region;
1243 struct rb_node *rb;
1244 unsigned long capabilities, vm_flags, result;
1245 int ret;
1246
1247 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1248
1249 /* decide whether we should attempt the mapping, and if so what sort of
1250 * mapping */
1251 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1252 &capabilities);
1253 if (ret < 0) {
1254 kleave(" = %d [val]", ret);
1255 return ret;
1256 }
1257
1258 /* we ignore the address hint */
1259 addr = 0;
1260 len = PAGE_ALIGN(len);
1261
1262 /* we've determined that we can make the mapping, now translate what we
1263 * now know into VMA flags */
1264 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1265
1266 /* we're going to need to record the mapping */
1267 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1268 if (!region)
1269 goto error_getting_region;
1270
1271 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1272 if (!vma)
1273 goto error_getting_vma;
1274
1275 region->vm_usage = 1;
1276 region->vm_flags = vm_flags;
1277 region->vm_pgoff = pgoff;
1278
1279 INIT_LIST_HEAD(&vma->anon_vma_chain);
1280 vma->vm_flags = vm_flags;
1281 vma->vm_pgoff = pgoff;
1282
1283 if (file) {
1284 region->vm_file = file;
1285 get_file(file);
1286 vma->vm_file = file;
1287 get_file(file);
1288 if (vm_flags & VM_EXECUTABLE) {
1289 added_exe_file_vma(current->mm);
1290 vma->vm_mm = current->mm;
1291 }
1292 }
1293
1294 down_write(&nommu_region_sem);
1295
1296 /* if we want to share, we need to check for regions created by other
1297 * mmap() calls that overlap with our proposed mapping
1298 * - we can only share with a superset match on most regular files
1299 * - shared mappings on character devices and memory backed files are
1300 * permitted to overlap inexactly as far as we are concerned for in
1301 * these cases, sharing is handled in the driver or filesystem rather
1302 * than here
1303 */
1304 if (vm_flags & VM_MAYSHARE) {
1305 struct vm_region *pregion;
1306 unsigned long pglen, rpglen, pgend, rpgend, start;
1307
1308 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1309 pgend = pgoff + pglen;
1310
1311 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1312 pregion = rb_entry(rb, struct vm_region, vm_rb);
1313
1314 if (!(pregion->vm_flags & VM_MAYSHARE))
1315 continue;
1316
1317 /* search for overlapping mappings on the same file */
1318 if (pregion->vm_file->f_path.dentry->d_inode !=
1319 file->f_path.dentry->d_inode)
1320 continue;
1321
1322 if (pregion->vm_pgoff >= pgend)
1323 continue;
1324
1325 rpglen = pregion->vm_end - pregion->vm_start;
1326 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1327 rpgend = pregion->vm_pgoff + rpglen;
1328 if (pgoff >= rpgend)
1329 continue;
1330
1331 /* handle inexactly overlapping matches between
1332 * mappings */
1333 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1334 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1335 /* new mapping is not a subset of the region */
1336 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1337 goto sharing_violation;
1338 continue;
1339 }
1340
1341 /* we've found a region we can share */
1342 pregion->vm_usage++;
1343 vma->vm_region = pregion;
1344 start = pregion->vm_start;
1345 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1346 vma->vm_start = start;
1347 vma->vm_end = start + len;
1348
1349 if (pregion->vm_flags & VM_MAPPED_COPY) {
1350 kdebug("share copy");
1351 vma->vm_flags |= VM_MAPPED_COPY;
1352 } else {
1353 kdebug("share mmap");
1354 ret = do_mmap_shared_file(vma);
1355 if (ret < 0) {
1356 vma->vm_region = NULL;
1357 vma->vm_start = 0;
1358 vma->vm_end = 0;
1359 pregion->vm_usage--;
1360 pregion = NULL;
1361 goto error_just_free;
1362 }
1363 }
1364 fput(region->vm_file);
1365 kmem_cache_free(vm_region_jar, region);
1366 region = pregion;
1367 result = start;
1368 goto share;
1369 }
1370
1371 /* obtain the address at which to make a shared mapping
1372 * - this is the hook for quasi-memory character devices to
1373 * tell us the location of a shared mapping
1374 */
1375 if (capabilities & BDI_CAP_MAP_DIRECT) {
1376 addr = file->f_op->get_unmapped_area(file, addr, len,
1377 pgoff, flags);
1378 if (IS_ERR_VALUE(addr)) {
1379 ret = addr;
1380 if (ret != -ENOSYS)
1381 goto error_just_free;
1382
1383 /* the driver refused to tell us where to site
1384 * the mapping so we'll have to attempt to copy
1385 * it */
1386 ret = -ENODEV;
1387 if (!(capabilities & BDI_CAP_MAP_COPY))
1388 goto error_just_free;
1389
1390 capabilities &= ~BDI_CAP_MAP_DIRECT;
1391 } else {
1392 vma->vm_start = region->vm_start = addr;
1393 vma->vm_end = region->vm_end = addr + len;
1394 }
1395 }
1396 }
1397
1398 vma->vm_region = region;
1399
1400 /* set up the mapping
1401 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1402 */
1403 if (file && vma->vm_flags & VM_SHARED)
1404 ret = do_mmap_shared_file(vma);
1405 else
1406 ret = do_mmap_private(vma, region, len, capabilities);
1407 if (ret < 0)
1408 goto error_just_free;
1409 add_nommu_region(region);
1410
1411 /* clear anonymous mappings that don't ask for uninitialized data */
1412 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1413 memset((void *)region->vm_start, 0,
1414 region->vm_end - region->vm_start);
1415
1416 /* okay... we have a mapping; now we have to register it */
1417 result = vma->vm_start;
1418
1419 current->mm->total_vm += len >> PAGE_SHIFT;
1420
1421share:
1422 add_vma_to_mm(current->mm, vma);
1423
1424 /* we flush the region from the icache only when the first executable
1425 * mapping of it is made */
1426 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1427 flush_icache_range(region->vm_start, region->vm_end);
1428 region->vm_icache_flushed = true;
1429 }
1430
1431 up_write(&nommu_region_sem);
1432
1433 kleave(" = %lx", result);
1434 return result;
1435
1436error_just_free:
1437 up_write(&nommu_region_sem);
1438error:
1439 if (region->vm_file)
1440 fput(region->vm_file);
1441 kmem_cache_free(vm_region_jar, region);
1442 if (vma->vm_file)
1443 fput(vma->vm_file);
1444 if (vma->vm_flags & VM_EXECUTABLE)
1445 removed_exe_file_vma(vma->vm_mm);
1446 kmem_cache_free(vm_area_cachep, vma);
1447 kleave(" = %d", ret);
1448 return ret;
1449
1450sharing_violation:
1451 up_write(&nommu_region_sem);
1452 printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1453 ret = -EINVAL;
1454 goto error;
1455
1456error_getting_vma:
1457 kmem_cache_free(vm_region_jar, region);
1458 printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1459 " from process %d failed\n",
1460 len, current->pid);
1461 show_free_areas(0);
1462 return -ENOMEM;
1463
1464error_getting_region:
1465 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1466 " from process %d failed\n",
1467 len, current->pid);
1468 show_free_areas(0);
1469 return -ENOMEM;
1470}
1471EXPORT_SYMBOL(do_mmap_pgoff);
1472
1473SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1474 unsigned long, prot, unsigned long, flags,
1475 unsigned long, fd, unsigned long, pgoff)
1476{
1477 struct file *file = NULL;
1478 unsigned long retval = -EBADF;
1479
1480 audit_mmap_fd(fd, flags);
1481 if (!(flags & MAP_ANONYMOUS)) {
1482 file = fget(fd);
1483 if (!file)
1484 goto out;
1485 }
1486
1487 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1488
1489 down_write(¤t->mm->mmap_sem);
1490 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1491 up_write(¤t->mm->mmap_sem);
1492
1493 if (file)
1494 fput(file);
1495out:
1496 return retval;
1497}
1498
1499#ifdef __ARCH_WANT_SYS_OLD_MMAP
1500struct mmap_arg_struct {
1501 unsigned long addr;
1502 unsigned long len;
1503 unsigned long prot;
1504 unsigned long flags;
1505 unsigned long fd;
1506 unsigned long offset;
1507};
1508
1509SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1510{
1511 struct mmap_arg_struct a;
1512
1513 if (copy_from_user(&a, arg, sizeof(a)))
1514 return -EFAULT;
1515 if (a.offset & ~PAGE_MASK)
1516 return -EINVAL;
1517
1518 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1519 a.offset >> PAGE_SHIFT);
1520}
1521#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1522
1523/*
1524 * split a vma into two pieces at address 'addr', a new vma is allocated either
1525 * for the first part or the tail.
1526 */
1527int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1528 unsigned long addr, int new_below)
1529{
1530 struct vm_area_struct *new;
1531 struct vm_region *region;
1532 unsigned long npages;
1533
1534 kenter("");
1535
1536 /* we're only permitted to split anonymous regions (these should have
1537 * only a single usage on the region) */
1538 if (vma->vm_file)
1539 return -ENOMEM;
1540
1541 if (mm->map_count >= sysctl_max_map_count)
1542 return -ENOMEM;
1543
1544 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1545 if (!region)
1546 return -ENOMEM;
1547
1548 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1549 if (!new) {
1550 kmem_cache_free(vm_region_jar, region);
1551 return -ENOMEM;
1552 }
1553
1554 /* most fields are the same, copy all, and then fixup */
1555 *new = *vma;
1556 *region = *vma->vm_region;
1557 new->vm_region = region;
1558
1559 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1560
1561 if (new_below) {
1562 region->vm_top = region->vm_end = new->vm_end = addr;
1563 } else {
1564 region->vm_start = new->vm_start = addr;
1565 region->vm_pgoff = new->vm_pgoff += npages;
1566 }
1567
1568 if (new->vm_ops && new->vm_ops->open)
1569 new->vm_ops->open(new);
1570
1571 delete_vma_from_mm(vma);
1572 down_write(&nommu_region_sem);
1573 delete_nommu_region(vma->vm_region);
1574 if (new_below) {
1575 vma->vm_region->vm_start = vma->vm_start = addr;
1576 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1577 } else {
1578 vma->vm_region->vm_end = vma->vm_end = addr;
1579 vma->vm_region->vm_top = addr;
1580 }
1581 add_nommu_region(vma->vm_region);
1582 add_nommu_region(new->vm_region);
1583 up_write(&nommu_region_sem);
1584 add_vma_to_mm(mm, vma);
1585 add_vma_to_mm(mm, new);
1586 return 0;
1587}
1588
1589/*
1590 * shrink a VMA by removing the specified chunk from either the beginning or
1591 * the end
1592 */
1593static int shrink_vma(struct mm_struct *mm,
1594 struct vm_area_struct *vma,
1595 unsigned long from, unsigned long to)
1596{
1597 struct vm_region *region;
1598
1599 kenter("");
1600
1601 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1602 * and list */
1603 delete_vma_from_mm(vma);
1604 if (from > vma->vm_start)
1605 vma->vm_end = from;
1606 else
1607 vma->vm_start = to;
1608 add_vma_to_mm(mm, vma);
1609
1610 /* cut the backing region down to size */
1611 region = vma->vm_region;
1612 BUG_ON(region->vm_usage != 1);
1613
1614 down_write(&nommu_region_sem);
1615 delete_nommu_region(region);
1616 if (from > region->vm_start) {
1617 to = region->vm_top;
1618 region->vm_top = region->vm_end = from;
1619 } else {
1620 region->vm_start = to;
1621 }
1622 add_nommu_region(region);
1623 up_write(&nommu_region_sem);
1624
1625 free_page_series(from, to);
1626 return 0;
1627}
1628
1629/*
1630 * release a mapping
1631 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1632 * VMA, though it need not cover the whole VMA
1633 */
1634int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1635{
1636 struct vm_area_struct *vma;
1637 unsigned long end;
1638 int ret;
1639
1640 kenter(",%lx,%zx", start, len);
1641
1642 len = PAGE_ALIGN(len);
1643 if (len == 0)
1644 return -EINVAL;
1645
1646 end = start + len;
1647
1648 /* find the first potentially overlapping VMA */
1649 vma = find_vma(mm, start);
1650 if (!vma) {
1651 static int limit = 0;
1652 if (limit < 5) {
1653 printk(KERN_WARNING
1654 "munmap of memory not mmapped by process %d"
1655 " (%s): 0x%lx-0x%lx\n",
1656 current->pid, current->comm,
1657 start, start + len - 1);
1658 limit++;
1659 }
1660 return -EINVAL;
1661 }
1662
1663 /* we're allowed to split an anonymous VMA but not a file-backed one */
1664 if (vma->vm_file) {
1665 do {
1666 if (start > vma->vm_start) {
1667 kleave(" = -EINVAL [miss]");
1668 return -EINVAL;
1669 }
1670 if (end == vma->vm_end)
1671 goto erase_whole_vma;
1672 vma = vma->vm_next;
1673 } while (vma);
1674 kleave(" = -EINVAL [split file]");
1675 return -EINVAL;
1676 } else {
1677 /* the chunk must be a subset of the VMA found */
1678 if (start == vma->vm_start && end == vma->vm_end)
1679 goto erase_whole_vma;
1680 if (start < vma->vm_start || end > vma->vm_end) {
1681 kleave(" = -EINVAL [superset]");
1682 return -EINVAL;
1683 }
1684 if (start & ~PAGE_MASK) {
1685 kleave(" = -EINVAL [unaligned start]");
1686 return -EINVAL;
1687 }
1688 if (end != vma->vm_end && end & ~PAGE_MASK) {
1689 kleave(" = -EINVAL [unaligned split]");
1690 return -EINVAL;
1691 }
1692 if (start != vma->vm_start && end != vma->vm_end) {
1693 ret = split_vma(mm, vma, start, 1);
1694 if (ret < 0) {
1695 kleave(" = %d [split]", ret);
1696 return ret;
1697 }
1698 }
1699 return shrink_vma(mm, vma, start, end);
1700 }
1701
1702erase_whole_vma:
1703 delete_vma_from_mm(vma);
1704 delete_vma(mm, vma);
1705 kleave(" = 0");
1706 return 0;
1707}
1708EXPORT_SYMBOL(do_munmap);
1709
1710SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1711{
1712 int ret;
1713 struct mm_struct *mm = current->mm;
1714
1715 down_write(&mm->mmap_sem);
1716 ret = do_munmap(mm, addr, len);
1717 up_write(&mm->mmap_sem);
1718 return ret;
1719}
1720
1721/*
1722 * release all the mappings made in a process's VM space
1723 */
1724void exit_mmap(struct mm_struct *mm)
1725{
1726 struct vm_area_struct *vma;
1727
1728 if (!mm)
1729 return;
1730
1731 kenter("");
1732
1733 mm->total_vm = 0;
1734
1735 while ((vma = mm->mmap)) {
1736 mm->mmap = vma->vm_next;
1737 delete_vma_from_mm(vma);
1738 delete_vma(mm, vma);
1739 cond_resched();
1740 }
1741
1742 kleave("");
1743}
1744
1745unsigned long do_brk(unsigned long addr, unsigned long len)
1746{
1747 return -ENOMEM;
1748}
1749
1750/*
1751 * expand (or shrink) an existing mapping, potentially moving it at the same
1752 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1753 *
1754 * under NOMMU conditions, we only permit changing a mapping's size, and only
1755 * as long as it stays within the region allocated by do_mmap_private() and the
1756 * block is not shareable
1757 *
1758 * MREMAP_FIXED is not supported under NOMMU conditions
1759 */
1760unsigned long do_mremap(unsigned long addr,
1761 unsigned long old_len, unsigned long new_len,
1762 unsigned long flags, unsigned long new_addr)
1763{
1764 struct vm_area_struct *vma;
1765
1766 /* insanity checks first */
1767 old_len = PAGE_ALIGN(old_len);
1768 new_len = PAGE_ALIGN(new_len);
1769 if (old_len == 0 || new_len == 0)
1770 return (unsigned long) -EINVAL;
1771
1772 if (addr & ~PAGE_MASK)
1773 return -EINVAL;
1774
1775 if (flags & MREMAP_FIXED && new_addr != addr)
1776 return (unsigned long) -EINVAL;
1777
1778 vma = find_vma_exact(current->mm, addr, old_len);
1779 if (!vma)
1780 return (unsigned long) -EINVAL;
1781
1782 if (vma->vm_end != vma->vm_start + old_len)
1783 return (unsigned long) -EFAULT;
1784
1785 if (vma->vm_flags & VM_MAYSHARE)
1786 return (unsigned long) -EPERM;
1787
1788 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1789 return (unsigned long) -ENOMEM;
1790
1791 /* all checks complete - do it */
1792 vma->vm_end = vma->vm_start + new_len;
1793 return vma->vm_start;
1794}
1795EXPORT_SYMBOL(do_mremap);
1796
1797SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1798 unsigned long, new_len, unsigned long, flags,
1799 unsigned long, new_addr)
1800{
1801 unsigned long ret;
1802
1803 down_write(¤t->mm->mmap_sem);
1804 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1805 up_write(¤t->mm->mmap_sem);
1806 return ret;
1807}
1808
1809struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1810 unsigned int foll_flags)
1811{
1812 return NULL;
1813}
1814
1815int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1816 unsigned long pfn, unsigned long size, pgprot_t prot)
1817{
1818 if (addr != (pfn << PAGE_SHIFT))
1819 return -EINVAL;
1820
1821 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1822 return 0;
1823}
1824EXPORT_SYMBOL(remap_pfn_range);
1825
1826int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1827 unsigned long pgoff)
1828{
1829 unsigned int size = vma->vm_end - vma->vm_start;
1830
1831 if (!(vma->vm_flags & VM_USERMAP))
1832 return -EINVAL;
1833
1834 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1835 vma->vm_end = vma->vm_start + size;
1836
1837 return 0;
1838}
1839EXPORT_SYMBOL(remap_vmalloc_range);
1840
1841unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1842 unsigned long len, unsigned long pgoff, unsigned long flags)
1843{
1844 return -ENOMEM;
1845}
1846
1847void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1848{
1849}
1850
1851void unmap_mapping_range(struct address_space *mapping,
1852 loff_t const holebegin, loff_t const holelen,
1853 int even_cows)
1854{
1855}
1856EXPORT_SYMBOL(unmap_mapping_range);
1857
1858/*
1859 * Check that a process has enough memory to allocate a new virtual
1860 * mapping. 0 means there is enough memory for the allocation to
1861 * succeed and -ENOMEM implies there is not.
1862 *
1863 * We currently support three overcommit policies, which are set via the
1864 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1865 *
1866 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1867 * Additional code 2002 Jul 20 by Robert Love.
1868 *
1869 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1870 *
1871 * Note this is a helper function intended to be used by LSMs which
1872 * wish to use this logic.
1873 */
1874int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1875{
1876 unsigned long free, allowed;
1877
1878 vm_acct_memory(pages);
1879
1880 /*
1881 * Sometimes we want to use more memory than we have
1882 */
1883 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1884 return 0;
1885
1886 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1887 free = global_page_state(NR_FREE_PAGES);
1888 free += global_page_state(NR_FILE_PAGES);
1889
1890 /*
1891 * shmem pages shouldn't be counted as free in this
1892 * case, they can't be purged, only swapped out, and
1893 * that won't affect the overall amount of available
1894 * memory in the system.
1895 */
1896 free -= global_page_state(NR_SHMEM);
1897
1898 free += nr_swap_pages;
1899
1900 /*
1901 * Any slabs which are created with the
1902 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1903 * which are reclaimable, under pressure. The dentry
1904 * cache and most inode caches should fall into this
1905 */
1906 free += global_page_state(NR_SLAB_RECLAIMABLE);
1907
1908 /*
1909 * Leave reserved pages. The pages are not for anonymous pages.
1910 */
1911 if (free <= totalreserve_pages)
1912 goto error;
1913 else
1914 free -= totalreserve_pages;
1915
1916 /*
1917 * Leave the last 3% for root
1918 */
1919 if (!cap_sys_admin)
1920 free -= free / 32;
1921
1922 if (free > pages)
1923 return 0;
1924
1925 goto error;
1926 }
1927
1928 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1929 /*
1930 * Leave the last 3% for root
1931 */
1932 if (!cap_sys_admin)
1933 allowed -= allowed / 32;
1934 allowed += total_swap_pages;
1935
1936 /* Don't let a single process grow too big:
1937 leave 3% of the size of this process for other processes */
1938 if (mm)
1939 allowed -= mm->total_vm / 32;
1940
1941 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1942 return 0;
1943
1944error:
1945 vm_unacct_memory(pages);
1946
1947 return -ENOMEM;
1948}
1949
1950int in_gate_area_no_mm(unsigned long addr)
1951{
1952 return 0;
1953}
1954
1955int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1956{
1957 BUG();
1958 return 0;
1959}
1960EXPORT_SYMBOL(filemap_fault);
1961
1962static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1963 unsigned long addr, void *buf, int len, int write)
1964{
1965 struct vm_area_struct *vma;
1966
1967 down_read(&mm->mmap_sem);
1968
1969 /* the access must start within one of the target process's mappings */
1970 vma = find_vma(mm, addr);
1971 if (vma) {
1972 /* don't overrun this mapping */
1973 if (addr + len >= vma->vm_end)
1974 len = vma->vm_end - addr;
1975
1976 /* only read or write mappings where it is permitted */
1977 if (write && vma->vm_flags & VM_MAYWRITE)
1978 copy_to_user_page(vma, NULL, addr,
1979 (void *) addr, buf, len);
1980 else if (!write && vma->vm_flags & VM_MAYREAD)
1981 copy_from_user_page(vma, NULL, addr,
1982 buf, (void *) addr, len);
1983 else
1984 len = 0;
1985 } else {
1986 len = 0;
1987 }
1988
1989 up_read(&mm->mmap_sem);
1990
1991 return len;
1992}
1993
1994/**
1995 * @access_remote_vm - access another process' address space
1996 * @mm: the mm_struct of the target address space
1997 * @addr: start address to access
1998 * @buf: source or destination buffer
1999 * @len: number of bytes to transfer
2000 * @write: whether the access is a write
2001 *
2002 * The caller must hold a reference on @mm.
2003 */
2004int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2005 void *buf, int len, int write)
2006{
2007 return __access_remote_vm(NULL, mm, addr, buf, len, write);
2008}
2009
2010/*
2011 * Access another process' address space.
2012 * - source/target buffer must be kernel space
2013 */
2014int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2015{
2016 struct mm_struct *mm;
2017
2018 if (addr + len < addr)
2019 return 0;
2020
2021 mm = get_task_mm(tsk);
2022 if (!mm)
2023 return 0;
2024
2025 len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2026
2027 mmput(mm);
2028 return len;
2029}
2030
2031/**
2032 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2033 * @inode: The inode to check
2034 * @size: The current filesize of the inode
2035 * @newsize: The proposed filesize of the inode
2036 *
2037 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2038 * make sure that that any outstanding VMAs aren't broken and then shrink the
2039 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2040 * automatically grant mappings that are too large.
2041 */
2042int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2043 size_t newsize)
2044{
2045 struct vm_area_struct *vma;
2046 struct prio_tree_iter iter;
2047 struct vm_region *region;
2048 pgoff_t low, high;
2049 size_t r_size, r_top;
2050
2051 low = newsize >> PAGE_SHIFT;
2052 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2053
2054 down_write(&nommu_region_sem);
2055
2056 /* search for VMAs that fall within the dead zone */
2057 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2058 low, high) {
2059 /* found one - only interested if it's shared out of the page
2060 * cache */
2061 if (vma->vm_flags & VM_SHARED) {
2062 up_write(&nommu_region_sem);
2063 return -ETXTBSY; /* not quite true, but near enough */
2064 }
2065 }
2066
2067 /* reduce any regions that overlap the dead zone - if in existence,
2068 * these will be pointed to by VMAs that don't overlap the dead zone
2069 *
2070 * we don't check for any regions that start beyond the EOF as there
2071 * shouldn't be any
2072 */
2073 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2074 0, ULONG_MAX) {
2075 if (!(vma->vm_flags & VM_SHARED))
2076 continue;
2077
2078 region = vma->vm_region;
2079 r_size = region->vm_top - region->vm_start;
2080 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2081
2082 if (r_top > newsize) {
2083 region->vm_top -= r_top - newsize;
2084 if (region->vm_end > region->vm_top)
2085 region->vm_end = region->vm_top;
2086 }
2087 }
2088
2089 up_write(&nommu_region_sem);
2090 return 0;
2091}