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

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