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