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