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1/*
2 * linux/mm/nommu.c
3 *
4 * Replacement code for mm functions to support CPU's that don't
5 * have any form of memory management unit (thus no virtual memory).
6 *
7 * See Documentation/nommu-mmap.txt
8 *
9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
13 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17
18#include <linux/export.h>
19#include <linux/mm.h>
20#include <linux/vmacache.h>
21#include <linux/mman.h>
22#include <linux/swap.h>
23#include <linux/file.h>
24#include <linux/highmem.h>
25#include <linux/pagemap.h>
26#include <linux/slab.h>
27#include <linux/vmalloc.h>
28#include <linux/blkdev.h>
29#include <linux/backing-dev.h>
30#include <linux/compiler.h>
31#include <linux/mount.h>
32#include <linux/personality.h>
33#include <linux/security.h>
34#include <linux/syscalls.h>
35#include <linux/audit.h>
36#include <linux/printk.h>
37
38#include <asm/uaccess.h>
39#include <asm/tlb.h>
40#include <asm/tlbflush.h>
41#include <asm/mmu_context.h>
42#include "internal.h"
43
44void *high_memory;
45EXPORT_SYMBOL(high_memory);
46struct page *mem_map;
47unsigned long max_mapnr;
48EXPORT_SYMBOL(max_mapnr);
49unsigned long highest_memmap_pfn;
50int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
51int heap_stack_gap = 0;
52
53atomic_long_t mmap_pages_allocated;
54
55EXPORT_SYMBOL(mem_map);
56
57/* list of mapped, potentially shareable regions */
58static struct kmem_cache *vm_region_jar;
59struct rb_root nommu_region_tree = RB_ROOT;
60DECLARE_RWSEM(nommu_region_sem);
61
62const struct vm_operations_struct generic_file_vm_ops = {
63};
64
65/*
66 * Return the total memory allocated for this pointer, not
67 * just what the caller asked for.
68 *
69 * Doesn't have to be accurate, i.e. may have races.
70 */
71unsigned int kobjsize(const void *objp)
72{
73 struct page *page;
74
75 /*
76 * If the object we have should not have ksize performed on it,
77 * return size of 0
78 */
79 if (!objp || !virt_addr_valid(objp))
80 return 0;
81
82 page = virt_to_head_page(objp);
83
84 /*
85 * If the allocator sets PageSlab, we know the pointer came from
86 * kmalloc().
87 */
88 if (PageSlab(page))
89 return ksize(objp);
90
91 /*
92 * If it's not a compound page, see if we have a matching VMA
93 * region. This test is intentionally done in reverse order,
94 * so if there's no VMA, we still fall through and hand back
95 * PAGE_SIZE for 0-order pages.
96 */
97 if (!PageCompound(page)) {
98 struct vm_area_struct *vma;
99
100 vma = find_vma(current->mm, (unsigned long)objp);
101 if (vma)
102 return vma->vm_end - vma->vm_start;
103 }
104
105 /*
106 * The ksize() function is only guaranteed to work for pointers
107 * returned by kmalloc(). So handle arbitrary pointers here.
108 */
109 return PAGE_SIZE << compound_order(page);
110}
111
112long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
113 unsigned long start, unsigned long nr_pages,
114 unsigned int foll_flags, struct page **pages,
115 struct vm_area_struct **vmas, int *nonblocking)
116{
117 struct vm_area_struct *vma;
118 unsigned long vm_flags;
119 int i;
120
121 /* calculate required read or write permissions.
122 * If FOLL_FORCE is set, we only require the "MAY" flags.
123 */
124 vm_flags = (foll_flags & FOLL_WRITE) ?
125 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
126 vm_flags &= (foll_flags & FOLL_FORCE) ?
127 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
128
129 for (i = 0; i < nr_pages; i++) {
130 vma = find_vma(mm, start);
131 if (!vma)
132 goto finish_or_fault;
133
134 /* protect what we can, including chardevs */
135 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
136 !(vm_flags & vma->vm_flags))
137 goto finish_or_fault;
138
139 if (pages) {
140 pages[i] = virt_to_page(start);
141 if (pages[i])
142 get_page(pages[i]);
143 }
144 if (vmas)
145 vmas[i] = vma;
146 start = (start + PAGE_SIZE) & PAGE_MASK;
147 }
148
149 return i;
150
151finish_or_fault:
152 return i ? : -EFAULT;
153}
154
155/*
156 * get a list of pages in an address range belonging to the specified process
157 * and indicate the VMA that covers each page
158 * - this is potentially dodgy as we may end incrementing the page count of a
159 * slab page or a secondary page from a compound page
160 * - don't permit access to VMAs that don't support it, such as I/O mappings
161 */
162long get_user_pages(unsigned long start, unsigned long nr_pages,
163 int write, int force, struct page **pages,
164 struct vm_area_struct **vmas)
165{
166 int flags = 0;
167
168 if (write)
169 flags |= FOLL_WRITE;
170 if (force)
171 flags |= FOLL_FORCE;
172
173 return __get_user_pages(current, current->mm, start, nr_pages, flags,
174 pages, vmas, NULL);
175}
176EXPORT_SYMBOL(get_user_pages);
177
178long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
179 int write, int force, struct page **pages,
180 int *locked)
181{
182 return get_user_pages(start, nr_pages, write, force, pages, NULL);
183}
184EXPORT_SYMBOL(get_user_pages_locked);
185
186long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
187 unsigned long start, unsigned long nr_pages,
188 int write, int force, struct page **pages,
189 unsigned int gup_flags)
190{
191 long ret;
192 down_read(&mm->mmap_sem);
193 ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
194 NULL, NULL);
195 up_read(&mm->mmap_sem);
196 return ret;
197}
198EXPORT_SYMBOL(__get_user_pages_unlocked);
199
200long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
201 int write, int force, struct page **pages)
202{
203 return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
204 write, force, pages, 0);
205}
206EXPORT_SYMBOL(get_user_pages_unlocked);
207
208/**
209 * follow_pfn - look up PFN at a user virtual address
210 * @vma: memory mapping
211 * @address: user virtual address
212 * @pfn: location to store found PFN
213 *
214 * Only IO mappings and raw PFN mappings are allowed.
215 *
216 * Returns zero and the pfn at @pfn on success, -ve otherwise.
217 */
218int follow_pfn(struct vm_area_struct *vma, unsigned long address,
219 unsigned long *pfn)
220{
221 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
222 return -EINVAL;
223
224 *pfn = address >> PAGE_SHIFT;
225 return 0;
226}
227EXPORT_SYMBOL(follow_pfn);
228
229LIST_HEAD(vmap_area_list);
230
231void vfree(const void *addr)
232{
233 kfree(addr);
234}
235EXPORT_SYMBOL(vfree);
236
237void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
238{
239 /*
240 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
241 * returns only a logical address.
242 */
243 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
244}
245EXPORT_SYMBOL(__vmalloc);
246
247void *vmalloc_user(unsigned long size)
248{
249 void *ret;
250
251 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
252 PAGE_KERNEL);
253 if (ret) {
254 struct vm_area_struct *vma;
255
256 down_write(¤t->mm->mmap_sem);
257 vma = find_vma(current->mm, (unsigned long)ret);
258 if (vma)
259 vma->vm_flags |= VM_USERMAP;
260 up_write(¤t->mm->mmap_sem);
261 }
262
263 return ret;
264}
265EXPORT_SYMBOL(vmalloc_user);
266
267struct page *vmalloc_to_page(const void *addr)
268{
269 return virt_to_page(addr);
270}
271EXPORT_SYMBOL(vmalloc_to_page);
272
273unsigned long vmalloc_to_pfn(const void *addr)
274{
275 return page_to_pfn(virt_to_page(addr));
276}
277EXPORT_SYMBOL(vmalloc_to_pfn);
278
279long vread(char *buf, char *addr, unsigned long count)
280{
281 /* Don't allow overflow */
282 if ((unsigned long) buf + count < count)
283 count = -(unsigned long) buf;
284
285 memcpy(buf, addr, count);
286 return count;
287}
288
289long vwrite(char *buf, char *addr, unsigned long count)
290{
291 /* Don't allow overflow */
292 if ((unsigned long) addr + count < count)
293 count = -(unsigned long) addr;
294
295 memcpy(addr, buf, count);
296 return count;
297}
298
299/*
300 * vmalloc - allocate virtually contiguous memory
301 *
302 * @size: allocation size
303 *
304 * Allocate enough pages to cover @size from the page level
305 * allocator and map them into contiguous kernel virtual space.
306 *
307 * For tight control over page level allocator and protection flags
308 * use __vmalloc() instead.
309 */
310void *vmalloc(unsigned long size)
311{
312 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
313}
314EXPORT_SYMBOL(vmalloc);
315
316/*
317 * vzalloc - allocate virtually contiguous memory with zero fill
318 *
319 * @size: allocation size
320 *
321 * Allocate enough pages to cover @size from the page level
322 * allocator and map them into contiguous kernel virtual space.
323 * The memory allocated is set to zero.
324 *
325 * For tight control over page level allocator and protection flags
326 * use __vmalloc() instead.
327 */
328void *vzalloc(unsigned long size)
329{
330 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
331 PAGE_KERNEL);
332}
333EXPORT_SYMBOL(vzalloc);
334
335/**
336 * vmalloc_node - allocate memory on a specific node
337 * @size: allocation size
338 * @node: numa node
339 *
340 * Allocate enough pages to cover @size from the page level
341 * allocator and map them into contiguous kernel virtual space.
342 *
343 * For tight control over page level allocator and protection flags
344 * use __vmalloc() instead.
345 */
346void *vmalloc_node(unsigned long size, int node)
347{
348 return vmalloc(size);
349}
350EXPORT_SYMBOL(vmalloc_node);
351
352/**
353 * vzalloc_node - allocate memory on a specific node with zero fill
354 * @size: allocation size
355 * @node: numa node
356 *
357 * Allocate enough pages to cover @size from the page level
358 * allocator and map them into contiguous kernel virtual space.
359 * The memory allocated is set to zero.
360 *
361 * For tight control over page level allocator and protection flags
362 * use __vmalloc() instead.
363 */
364void *vzalloc_node(unsigned long size, int node)
365{
366 return vzalloc(size);
367}
368EXPORT_SYMBOL(vzalloc_node);
369
370#ifndef PAGE_KERNEL_EXEC
371# define PAGE_KERNEL_EXEC PAGE_KERNEL
372#endif
373
374/**
375 * vmalloc_exec - allocate virtually contiguous, executable memory
376 * @size: allocation size
377 *
378 * Kernel-internal function to allocate enough pages to cover @size
379 * the page level allocator and map them into contiguous and
380 * executable kernel virtual space.
381 *
382 * For tight control over page level allocator and protection flags
383 * use __vmalloc() instead.
384 */
385
386void *vmalloc_exec(unsigned long size)
387{
388 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
389}
390
391/**
392 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
393 * @size: allocation size
394 *
395 * Allocate enough 32bit PA addressable pages to cover @size from the
396 * page level allocator and map them into contiguous kernel virtual space.
397 */
398void *vmalloc_32(unsigned long size)
399{
400 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
401}
402EXPORT_SYMBOL(vmalloc_32);
403
404/**
405 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
406 * @size: allocation size
407 *
408 * The resulting memory area is 32bit addressable and zeroed so it can be
409 * mapped to userspace without leaking data.
410 *
411 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
412 * remap_vmalloc_range() are permissible.
413 */
414void *vmalloc_32_user(unsigned long size)
415{
416 /*
417 * We'll have to sort out the ZONE_DMA bits for 64-bit,
418 * but for now this can simply use vmalloc_user() directly.
419 */
420 return vmalloc_user(size);
421}
422EXPORT_SYMBOL(vmalloc_32_user);
423
424void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
425{
426 BUG();
427 return NULL;
428}
429EXPORT_SYMBOL(vmap);
430
431void vunmap(const void *addr)
432{
433 BUG();
434}
435EXPORT_SYMBOL(vunmap);
436
437void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
438{
439 BUG();
440 return NULL;
441}
442EXPORT_SYMBOL(vm_map_ram);
443
444void vm_unmap_ram(const void *mem, unsigned int count)
445{
446 BUG();
447}
448EXPORT_SYMBOL(vm_unmap_ram);
449
450void vm_unmap_aliases(void)
451{
452}
453EXPORT_SYMBOL_GPL(vm_unmap_aliases);
454
455/*
456 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
457 * have one.
458 */
459void __weak vmalloc_sync_all(void)
460{
461}
462
463/**
464 * alloc_vm_area - allocate a range of kernel address space
465 * @size: size of the area
466 *
467 * Returns: NULL on failure, vm_struct on success
468 *
469 * This function reserves a range of kernel address space, and
470 * allocates pagetables to map that range. No actual mappings
471 * are created. If the kernel address space is not shared
472 * between processes, it syncs the pagetable across all
473 * processes.
474 */
475struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
476{
477 BUG();
478 return NULL;
479}
480EXPORT_SYMBOL_GPL(alloc_vm_area);
481
482void free_vm_area(struct vm_struct *area)
483{
484 BUG();
485}
486EXPORT_SYMBOL_GPL(free_vm_area);
487
488int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
489 struct page *page)
490{
491 return -EINVAL;
492}
493EXPORT_SYMBOL(vm_insert_page);
494
495/*
496 * sys_brk() for the most part doesn't need the global kernel
497 * lock, except when an application is doing something nasty
498 * like trying to un-brk an area that has already been mapped
499 * to a regular file. in this case, the unmapping will need
500 * to invoke file system routines that need the global lock.
501 */
502SYSCALL_DEFINE1(brk, unsigned long, brk)
503{
504 struct mm_struct *mm = current->mm;
505
506 if (brk < mm->start_brk || brk > mm->context.end_brk)
507 return mm->brk;
508
509 if (mm->brk == brk)
510 return mm->brk;
511
512 /*
513 * Always allow shrinking brk
514 */
515 if (brk <= mm->brk) {
516 mm->brk = brk;
517 return brk;
518 }
519
520 /*
521 * Ok, looks good - let it rip.
522 */
523 flush_icache_range(mm->brk, brk);
524 return mm->brk = brk;
525}
526
527/*
528 * initialise the VMA and region record slabs
529 */
530void __init mmap_init(void)
531{
532 int ret;
533
534 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
535 VM_BUG_ON(ret);
536 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
537}
538
539/*
540 * validate the region tree
541 * - the caller must hold the region lock
542 */
543#ifdef CONFIG_DEBUG_NOMMU_REGIONS
544static noinline void validate_nommu_regions(void)
545{
546 struct vm_region *region, *last;
547 struct rb_node *p, *lastp;
548
549 lastp = rb_first(&nommu_region_tree);
550 if (!lastp)
551 return;
552
553 last = rb_entry(lastp, struct vm_region, vm_rb);
554 BUG_ON(last->vm_end <= last->vm_start);
555 BUG_ON(last->vm_top < last->vm_end);
556
557 while ((p = rb_next(lastp))) {
558 region = rb_entry(p, struct vm_region, vm_rb);
559 last = rb_entry(lastp, struct vm_region, vm_rb);
560
561 BUG_ON(region->vm_end <= region->vm_start);
562 BUG_ON(region->vm_top < region->vm_end);
563 BUG_ON(region->vm_start < last->vm_top);
564
565 lastp = p;
566 }
567}
568#else
569static void validate_nommu_regions(void)
570{
571}
572#endif
573
574/*
575 * add a region into the global tree
576 */
577static void add_nommu_region(struct vm_region *region)
578{
579 struct vm_region *pregion;
580 struct rb_node **p, *parent;
581
582 validate_nommu_regions();
583
584 parent = NULL;
585 p = &nommu_region_tree.rb_node;
586 while (*p) {
587 parent = *p;
588 pregion = rb_entry(parent, struct vm_region, vm_rb);
589 if (region->vm_start < pregion->vm_start)
590 p = &(*p)->rb_left;
591 else if (region->vm_start > pregion->vm_start)
592 p = &(*p)->rb_right;
593 else if (pregion == region)
594 return;
595 else
596 BUG();
597 }
598
599 rb_link_node(®ion->vm_rb, parent, p);
600 rb_insert_color(®ion->vm_rb, &nommu_region_tree);
601
602 validate_nommu_regions();
603}
604
605/*
606 * delete a region from the global tree
607 */
608static void delete_nommu_region(struct vm_region *region)
609{
610 BUG_ON(!nommu_region_tree.rb_node);
611
612 validate_nommu_regions();
613 rb_erase(®ion->vm_rb, &nommu_region_tree);
614 validate_nommu_regions();
615}
616
617/*
618 * free a contiguous series of pages
619 */
620static void free_page_series(unsigned long from, unsigned long to)
621{
622 for (; from < to; from += PAGE_SIZE) {
623 struct page *page = virt_to_page(from);
624
625 atomic_long_dec(&mmap_pages_allocated);
626 put_page(page);
627 }
628}
629
630/*
631 * release a reference to a region
632 * - the caller must hold the region semaphore for writing, which this releases
633 * - the region may not have been added to the tree yet, in which case vm_top
634 * will equal vm_start
635 */
636static void __put_nommu_region(struct vm_region *region)
637 __releases(nommu_region_sem)
638{
639 BUG_ON(!nommu_region_tree.rb_node);
640
641 if (--region->vm_usage == 0) {
642 if (region->vm_top > region->vm_start)
643 delete_nommu_region(region);
644 up_write(&nommu_region_sem);
645
646 if (region->vm_file)
647 fput(region->vm_file);
648
649 /* IO memory and memory shared directly out of the pagecache
650 * from ramfs/tmpfs mustn't be released here */
651 if (region->vm_flags & VM_MAPPED_COPY)
652 free_page_series(region->vm_start, region->vm_top);
653 kmem_cache_free(vm_region_jar, region);
654 } else {
655 up_write(&nommu_region_sem);
656 }
657}
658
659/*
660 * release a reference to a region
661 */
662static void put_nommu_region(struct vm_region *region)
663{
664 down_write(&nommu_region_sem);
665 __put_nommu_region(region);
666}
667
668/*
669 * update protection on a vma
670 */
671static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
672{
673#ifdef CONFIG_MPU
674 struct mm_struct *mm = vma->vm_mm;
675 long start = vma->vm_start & PAGE_MASK;
676 while (start < vma->vm_end) {
677 protect_page(mm, start, flags);
678 start += PAGE_SIZE;
679 }
680 update_protections(mm);
681#endif
682}
683
684/*
685 * add a VMA into a process's mm_struct in the appropriate place in the list
686 * and tree and add to the address space's page tree also if not an anonymous
687 * page
688 * - should be called with mm->mmap_sem held writelocked
689 */
690static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
691{
692 struct vm_area_struct *pvma, *prev;
693 struct address_space *mapping;
694 struct rb_node **p, *parent, *rb_prev;
695
696 BUG_ON(!vma->vm_region);
697
698 mm->map_count++;
699 vma->vm_mm = mm;
700
701 protect_vma(vma, vma->vm_flags);
702
703 /* add the VMA to the mapping */
704 if (vma->vm_file) {
705 mapping = vma->vm_file->f_mapping;
706
707 i_mmap_lock_write(mapping);
708 flush_dcache_mmap_lock(mapping);
709 vma_interval_tree_insert(vma, &mapping->i_mmap);
710 flush_dcache_mmap_unlock(mapping);
711 i_mmap_unlock_write(mapping);
712 }
713
714 /* add the VMA to the tree */
715 parent = rb_prev = NULL;
716 p = &mm->mm_rb.rb_node;
717 while (*p) {
718 parent = *p;
719 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
720
721 /* sort by: start addr, end addr, VMA struct addr in that order
722 * (the latter is necessary as we may get identical VMAs) */
723 if (vma->vm_start < pvma->vm_start)
724 p = &(*p)->rb_left;
725 else if (vma->vm_start > pvma->vm_start) {
726 rb_prev = parent;
727 p = &(*p)->rb_right;
728 } else if (vma->vm_end < pvma->vm_end)
729 p = &(*p)->rb_left;
730 else if (vma->vm_end > pvma->vm_end) {
731 rb_prev = parent;
732 p = &(*p)->rb_right;
733 } else if (vma < pvma)
734 p = &(*p)->rb_left;
735 else if (vma > pvma) {
736 rb_prev = parent;
737 p = &(*p)->rb_right;
738 } else
739 BUG();
740 }
741
742 rb_link_node(&vma->vm_rb, parent, p);
743 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
744
745 /* add VMA to the VMA list also */
746 prev = NULL;
747 if (rb_prev)
748 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
749
750 __vma_link_list(mm, vma, prev, parent);
751}
752
753/*
754 * delete a VMA from its owning mm_struct and address space
755 */
756static void delete_vma_from_mm(struct vm_area_struct *vma)
757{
758 int i;
759 struct address_space *mapping;
760 struct mm_struct *mm = vma->vm_mm;
761 struct task_struct *curr = current;
762
763 protect_vma(vma, 0);
764
765 mm->map_count--;
766 for (i = 0; i < VMACACHE_SIZE; i++) {
767 /* if the vma is cached, invalidate the entire cache */
768 if (curr->vmacache[i] == vma) {
769 vmacache_invalidate(mm);
770 break;
771 }
772 }
773
774 /* remove the VMA from the mapping */
775 if (vma->vm_file) {
776 mapping = vma->vm_file->f_mapping;
777
778 i_mmap_lock_write(mapping);
779 flush_dcache_mmap_lock(mapping);
780 vma_interval_tree_remove(vma, &mapping->i_mmap);
781 flush_dcache_mmap_unlock(mapping);
782 i_mmap_unlock_write(mapping);
783 }
784
785 /* remove from the MM's tree and list */
786 rb_erase(&vma->vm_rb, &mm->mm_rb);
787
788 if (vma->vm_prev)
789 vma->vm_prev->vm_next = vma->vm_next;
790 else
791 mm->mmap = vma->vm_next;
792
793 if (vma->vm_next)
794 vma->vm_next->vm_prev = vma->vm_prev;
795}
796
797/*
798 * destroy a VMA record
799 */
800static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
801{
802 if (vma->vm_ops && vma->vm_ops->close)
803 vma->vm_ops->close(vma);
804 if (vma->vm_file)
805 fput(vma->vm_file);
806 put_nommu_region(vma->vm_region);
807 kmem_cache_free(vm_area_cachep, vma);
808}
809
810/*
811 * look up the first VMA in which addr resides, NULL if none
812 * - should be called with mm->mmap_sem at least held readlocked
813 */
814struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
815{
816 struct vm_area_struct *vma;
817
818 /* check the cache first */
819 vma = vmacache_find(mm, addr);
820 if (likely(vma))
821 return vma;
822
823 /* trawl the list (there may be multiple mappings in which addr
824 * resides) */
825 for (vma = mm->mmap; vma; vma = vma->vm_next) {
826 if (vma->vm_start > addr)
827 return NULL;
828 if (vma->vm_end > addr) {
829 vmacache_update(addr, vma);
830 return vma;
831 }
832 }
833
834 return NULL;
835}
836EXPORT_SYMBOL(find_vma);
837
838/*
839 * find a VMA
840 * - we don't extend stack VMAs under NOMMU conditions
841 */
842struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
843{
844 return find_vma(mm, addr);
845}
846
847/*
848 * expand a stack to a given address
849 * - not supported under NOMMU conditions
850 */
851int expand_stack(struct vm_area_struct *vma, unsigned long address)
852{
853 return -ENOMEM;
854}
855
856/*
857 * look up the first VMA exactly that exactly matches addr
858 * - should be called with mm->mmap_sem at least held readlocked
859 */
860static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
861 unsigned long addr,
862 unsigned long len)
863{
864 struct vm_area_struct *vma;
865 unsigned long end = addr + len;
866
867 /* check the cache first */
868 vma = vmacache_find_exact(mm, addr, end);
869 if (vma)
870 return vma;
871
872 /* trawl the list (there may be multiple mappings in which addr
873 * resides) */
874 for (vma = mm->mmap; vma; vma = vma->vm_next) {
875 if (vma->vm_start < addr)
876 continue;
877 if (vma->vm_start > addr)
878 return NULL;
879 if (vma->vm_end == end) {
880 vmacache_update(addr, vma);
881 return vma;
882 }
883 }
884
885 return NULL;
886}
887
888/*
889 * determine whether a mapping should be permitted and, if so, what sort of
890 * mapping we're capable of supporting
891 */
892static int validate_mmap_request(struct file *file,
893 unsigned long addr,
894 unsigned long len,
895 unsigned long prot,
896 unsigned long flags,
897 unsigned long pgoff,
898 unsigned long *_capabilities)
899{
900 unsigned long capabilities, rlen;
901 int ret;
902
903 /* do the simple checks first */
904 if (flags & MAP_FIXED)
905 return -EINVAL;
906
907 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
908 (flags & MAP_TYPE) != MAP_SHARED)
909 return -EINVAL;
910
911 if (!len)
912 return -EINVAL;
913
914 /* Careful about overflows.. */
915 rlen = PAGE_ALIGN(len);
916 if (!rlen || rlen > TASK_SIZE)
917 return -ENOMEM;
918
919 /* offset overflow? */
920 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
921 return -EOVERFLOW;
922
923 if (file) {
924 /* files must support mmap */
925 if (!file->f_op->mmap)
926 return -ENODEV;
927
928 /* work out if what we've got could possibly be shared
929 * - we support chardevs that provide their own "memory"
930 * - we support files/blockdevs that are memory backed
931 */
932 if (file->f_op->mmap_capabilities) {
933 capabilities = file->f_op->mmap_capabilities(file);
934 } else {
935 /* no explicit capabilities set, so assume some
936 * defaults */
937 switch (file_inode(file)->i_mode & S_IFMT) {
938 case S_IFREG:
939 case S_IFBLK:
940 capabilities = NOMMU_MAP_COPY;
941 break;
942
943 case S_IFCHR:
944 capabilities =
945 NOMMU_MAP_DIRECT |
946 NOMMU_MAP_READ |
947 NOMMU_MAP_WRITE;
948 break;
949
950 default:
951 return -EINVAL;
952 }
953 }
954
955 /* eliminate any capabilities that we can't support on this
956 * device */
957 if (!file->f_op->get_unmapped_area)
958 capabilities &= ~NOMMU_MAP_DIRECT;
959 if (!(file->f_mode & FMODE_CAN_READ))
960 capabilities &= ~NOMMU_MAP_COPY;
961
962 /* The file shall have been opened with read permission. */
963 if (!(file->f_mode & FMODE_READ))
964 return -EACCES;
965
966 if (flags & MAP_SHARED) {
967 /* do checks for writing, appending and locking */
968 if ((prot & PROT_WRITE) &&
969 !(file->f_mode & FMODE_WRITE))
970 return -EACCES;
971
972 if (IS_APPEND(file_inode(file)) &&
973 (file->f_mode & FMODE_WRITE))
974 return -EACCES;
975
976 if (locks_verify_locked(file))
977 return -EAGAIN;
978
979 if (!(capabilities & NOMMU_MAP_DIRECT))
980 return -ENODEV;
981
982 /* we mustn't privatise shared mappings */
983 capabilities &= ~NOMMU_MAP_COPY;
984 } else {
985 /* we're going to read the file into private memory we
986 * allocate */
987 if (!(capabilities & NOMMU_MAP_COPY))
988 return -ENODEV;
989
990 /* we don't permit a private writable mapping to be
991 * shared with the backing device */
992 if (prot & PROT_WRITE)
993 capabilities &= ~NOMMU_MAP_DIRECT;
994 }
995
996 if (capabilities & NOMMU_MAP_DIRECT) {
997 if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) ||
998 ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
999 ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC))
1000 ) {
1001 capabilities &= ~NOMMU_MAP_DIRECT;
1002 if (flags & MAP_SHARED) {
1003 pr_warn("MAP_SHARED not completely supported on !MMU\n");
1004 return -EINVAL;
1005 }
1006 }
1007 }
1008
1009 /* handle executable mappings and implied executable
1010 * mappings */
1011 if (path_noexec(&file->f_path)) {
1012 if (prot & PROT_EXEC)
1013 return -EPERM;
1014 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1015 /* handle implication of PROT_EXEC by PROT_READ */
1016 if (current->personality & READ_IMPLIES_EXEC) {
1017 if (capabilities & NOMMU_MAP_EXEC)
1018 prot |= PROT_EXEC;
1019 }
1020 } else if ((prot & PROT_READ) &&
1021 (prot & PROT_EXEC) &&
1022 !(capabilities & NOMMU_MAP_EXEC)
1023 ) {
1024 /* backing file is not executable, try to copy */
1025 capabilities &= ~NOMMU_MAP_DIRECT;
1026 }
1027 } else {
1028 /* anonymous mappings are always memory backed and can be
1029 * privately mapped
1030 */
1031 capabilities = NOMMU_MAP_COPY;
1032
1033 /* handle PROT_EXEC implication by PROT_READ */
1034 if ((prot & PROT_READ) &&
1035 (current->personality & READ_IMPLIES_EXEC))
1036 prot |= PROT_EXEC;
1037 }
1038
1039 /* allow the security API to have its say */
1040 ret = security_mmap_addr(addr);
1041 if (ret < 0)
1042 return ret;
1043
1044 /* looks okay */
1045 *_capabilities = capabilities;
1046 return 0;
1047}
1048
1049/*
1050 * we've determined that we can make the mapping, now translate what we
1051 * now know into VMA flags
1052 */
1053static unsigned long determine_vm_flags(struct file *file,
1054 unsigned long prot,
1055 unsigned long flags,
1056 unsigned long capabilities)
1057{
1058 unsigned long vm_flags;
1059
1060 vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
1061 /* vm_flags |= mm->def_flags; */
1062
1063 if (!(capabilities & NOMMU_MAP_DIRECT)) {
1064 /* attempt to share read-only copies of mapped file chunks */
1065 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1066 if (file && !(prot & PROT_WRITE))
1067 vm_flags |= VM_MAYSHARE;
1068 } else {
1069 /* overlay a shareable mapping on the backing device or inode
1070 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1071 * romfs/cramfs */
1072 vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
1073 if (flags & MAP_SHARED)
1074 vm_flags |= VM_SHARED;
1075 }
1076
1077 /* refuse to let anyone share private mappings with this process if
1078 * it's being traced - otherwise breakpoints set in it may interfere
1079 * with another untraced process
1080 */
1081 if ((flags & MAP_PRIVATE) && current->ptrace)
1082 vm_flags &= ~VM_MAYSHARE;
1083
1084 return vm_flags;
1085}
1086
1087/*
1088 * set up a shared mapping on a file (the driver or filesystem provides and
1089 * pins the storage)
1090 */
1091static int do_mmap_shared_file(struct vm_area_struct *vma)
1092{
1093 int ret;
1094
1095 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1096 if (ret == 0) {
1097 vma->vm_region->vm_top = vma->vm_region->vm_end;
1098 return 0;
1099 }
1100 if (ret != -ENOSYS)
1101 return ret;
1102
1103 /* getting -ENOSYS indicates that direct mmap isn't possible (as
1104 * opposed to tried but failed) so we can only give a suitable error as
1105 * it's not possible to make a private copy if MAP_SHARED was given */
1106 return -ENODEV;
1107}
1108
1109/*
1110 * set up a private mapping or an anonymous shared mapping
1111 */
1112static int do_mmap_private(struct vm_area_struct *vma,
1113 struct vm_region *region,
1114 unsigned long len,
1115 unsigned long capabilities)
1116{
1117 unsigned long total, point;
1118 void *base;
1119 int ret, order;
1120
1121 /* invoke the file's mapping function so that it can keep track of
1122 * shared mappings on devices or memory
1123 * - VM_MAYSHARE will be set if it may attempt to share
1124 */
1125 if (capabilities & NOMMU_MAP_DIRECT) {
1126 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1127 if (ret == 0) {
1128 /* shouldn't return success if we're not sharing */
1129 BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1130 vma->vm_region->vm_top = vma->vm_region->vm_end;
1131 return 0;
1132 }
1133 if (ret != -ENOSYS)
1134 return ret;
1135
1136 /* getting an ENOSYS error indicates that direct mmap isn't
1137 * possible (as opposed to tried but failed) so we'll try to
1138 * make a private copy of the data and map that instead */
1139 }
1140
1141
1142 /* allocate some memory to hold the mapping
1143 * - note that this may not return a page-aligned address if the object
1144 * we're allocating is smaller than a page
1145 */
1146 order = get_order(len);
1147 total = 1 << order;
1148 point = len >> PAGE_SHIFT;
1149
1150 /* we don't want to allocate a power-of-2 sized page set */
1151 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
1152 total = point;
1153
1154 base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
1155 if (!base)
1156 goto enomem;
1157
1158 atomic_long_add(total, &mmap_pages_allocated);
1159
1160 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1161 region->vm_start = (unsigned long) base;
1162 region->vm_end = region->vm_start + len;
1163 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
1164
1165 vma->vm_start = region->vm_start;
1166 vma->vm_end = region->vm_start + len;
1167
1168 if (vma->vm_file) {
1169 /* read the contents of a file into the copy */
1170 mm_segment_t old_fs;
1171 loff_t fpos;
1172
1173 fpos = vma->vm_pgoff;
1174 fpos <<= PAGE_SHIFT;
1175
1176 old_fs = get_fs();
1177 set_fs(KERNEL_DS);
1178 ret = __vfs_read(vma->vm_file, base, len, &fpos);
1179 set_fs(old_fs);
1180
1181 if (ret < 0)
1182 goto error_free;
1183
1184 /* clear the last little bit */
1185 if (ret < len)
1186 memset(base + ret, 0, len - ret);
1187
1188 }
1189
1190 return 0;
1191
1192error_free:
1193 free_page_series(region->vm_start, region->vm_top);
1194 region->vm_start = vma->vm_start = 0;
1195 region->vm_end = vma->vm_end = 0;
1196 region->vm_top = 0;
1197 return ret;
1198
1199enomem:
1200 pr_err("Allocation of length %lu from process %d (%s) failed\n",
1201 len, current->pid, current->comm);
1202 show_free_areas(0);
1203 return -ENOMEM;
1204}
1205
1206/*
1207 * handle mapping creation for uClinux
1208 */
1209unsigned long do_mmap(struct file *file,
1210 unsigned long addr,
1211 unsigned long len,
1212 unsigned long prot,
1213 unsigned long flags,
1214 vm_flags_t vm_flags,
1215 unsigned long pgoff,
1216 unsigned long *populate)
1217{
1218 struct vm_area_struct *vma;
1219 struct vm_region *region;
1220 struct rb_node *rb;
1221 unsigned long capabilities, result;
1222 int ret;
1223
1224 *populate = 0;
1225
1226 /* decide whether we should attempt the mapping, and if so what sort of
1227 * mapping */
1228 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1229 &capabilities);
1230 if (ret < 0)
1231 return ret;
1232
1233 /* we ignore the address hint */
1234 addr = 0;
1235 len = PAGE_ALIGN(len);
1236
1237 /* we've determined that we can make the mapping, now translate what we
1238 * now know into VMA flags */
1239 vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1240
1241 /* we're going to need to record the mapping */
1242 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1243 if (!region)
1244 goto error_getting_region;
1245
1246 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1247 if (!vma)
1248 goto error_getting_vma;
1249
1250 region->vm_usage = 1;
1251 region->vm_flags = vm_flags;
1252 region->vm_pgoff = pgoff;
1253
1254 INIT_LIST_HEAD(&vma->anon_vma_chain);
1255 vma->vm_flags = vm_flags;
1256 vma->vm_pgoff = pgoff;
1257
1258 if (file) {
1259 region->vm_file = get_file(file);
1260 vma->vm_file = get_file(file);
1261 }
1262
1263 down_write(&nommu_region_sem);
1264
1265 /* if we want to share, we need to check for regions created by other
1266 * mmap() calls that overlap with our proposed mapping
1267 * - we can only share with a superset match on most regular files
1268 * - shared mappings on character devices and memory backed files are
1269 * permitted to overlap inexactly as far as we are concerned for in
1270 * these cases, sharing is handled in the driver or filesystem rather
1271 * than here
1272 */
1273 if (vm_flags & VM_MAYSHARE) {
1274 struct vm_region *pregion;
1275 unsigned long pglen, rpglen, pgend, rpgend, start;
1276
1277 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1278 pgend = pgoff + pglen;
1279
1280 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1281 pregion = rb_entry(rb, struct vm_region, vm_rb);
1282
1283 if (!(pregion->vm_flags & VM_MAYSHARE))
1284 continue;
1285
1286 /* search for overlapping mappings on the same file */
1287 if (file_inode(pregion->vm_file) !=
1288 file_inode(file))
1289 continue;
1290
1291 if (pregion->vm_pgoff >= pgend)
1292 continue;
1293
1294 rpglen = pregion->vm_end - pregion->vm_start;
1295 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1296 rpgend = pregion->vm_pgoff + rpglen;
1297 if (pgoff >= rpgend)
1298 continue;
1299
1300 /* handle inexactly overlapping matches between
1301 * mappings */
1302 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1303 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1304 /* new mapping is not a subset of the region */
1305 if (!(capabilities & NOMMU_MAP_DIRECT))
1306 goto sharing_violation;
1307 continue;
1308 }
1309
1310 /* we've found a region we can share */
1311 pregion->vm_usage++;
1312 vma->vm_region = pregion;
1313 start = pregion->vm_start;
1314 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1315 vma->vm_start = start;
1316 vma->vm_end = start + len;
1317
1318 if (pregion->vm_flags & VM_MAPPED_COPY)
1319 vma->vm_flags |= VM_MAPPED_COPY;
1320 else {
1321 ret = do_mmap_shared_file(vma);
1322 if (ret < 0) {
1323 vma->vm_region = NULL;
1324 vma->vm_start = 0;
1325 vma->vm_end = 0;
1326 pregion->vm_usage--;
1327 pregion = NULL;
1328 goto error_just_free;
1329 }
1330 }
1331 fput(region->vm_file);
1332 kmem_cache_free(vm_region_jar, region);
1333 region = pregion;
1334 result = start;
1335 goto share;
1336 }
1337
1338 /* obtain the address at which to make a shared mapping
1339 * - this is the hook for quasi-memory character devices to
1340 * tell us the location of a shared mapping
1341 */
1342 if (capabilities & NOMMU_MAP_DIRECT) {
1343 addr = file->f_op->get_unmapped_area(file, addr, len,
1344 pgoff, flags);
1345 if (IS_ERR_VALUE(addr)) {
1346 ret = addr;
1347 if (ret != -ENOSYS)
1348 goto error_just_free;
1349
1350 /* the driver refused to tell us where to site
1351 * the mapping so we'll have to attempt to copy
1352 * it */
1353 ret = -ENODEV;
1354 if (!(capabilities & NOMMU_MAP_COPY))
1355 goto error_just_free;
1356
1357 capabilities &= ~NOMMU_MAP_DIRECT;
1358 } else {
1359 vma->vm_start = region->vm_start = addr;
1360 vma->vm_end = region->vm_end = addr + len;
1361 }
1362 }
1363 }
1364
1365 vma->vm_region = region;
1366
1367 /* set up the mapping
1368 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1369 */
1370 if (file && vma->vm_flags & VM_SHARED)
1371 ret = do_mmap_shared_file(vma);
1372 else
1373 ret = do_mmap_private(vma, region, len, capabilities);
1374 if (ret < 0)
1375 goto error_just_free;
1376 add_nommu_region(region);
1377
1378 /* clear anonymous mappings that don't ask for uninitialized data */
1379 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1380 memset((void *)region->vm_start, 0,
1381 region->vm_end - region->vm_start);
1382
1383 /* okay... we have a mapping; now we have to register it */
1384 result = vma->vm_start;
1385
1386 current->mm->total_vm += len >> PAGE_SHIFT;
1387
1388share:
1389 add_vma_to_mm(current->mm, vma);
1390
1391 /* we flush the region from the icache only when the first executable
1392 * mapping of it is made */
1393 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1394 flush_icache_range(region->vm_start, region->vm_end);
1395 region->vm_icache_flushed = true;
1396 }
1397
1398 up_write(&nommu_region_sem);
1399
1400 return result;
1401
1402error_just_free:
1403 up_write(&nommu_region_sem);
1404error:
1405 if (region->vm_file)
1406 fput(region->vm_file);
1407 kmem_cache_free(vm_region_jar, region);
1408 if (vma->vm_file)
1409 fput(vma->vm_file);
1410 kmem_cache_free(vm_area_cachep, vma);
1411 return ret;
1412
1413sharing_violation:
1414 up_write(&nommu_region_sem);
1415 pr_warn("Attempt to share mismatched mappings\n");
1416 ret = -EINVAL;
1417 goto error;
1418
1419error_getting_vma:
1420 kmem_cache_free(vm_region_jar, region);
1421 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1422 len, current->pid);
1423 show_free_areas(0);
1424 return -ENOMEM;
1425
1426error_getting_region:
1427 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1428 len, current->pid);
1429 show_free_areas(0);
1430 return -ENOMEM;
1431}
1432
1433SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1434 unsigned long, prot, unsigned long, flags,
1435 unsigned long, fd, unsigned long, pgoff)
1436{
1437 struct file *file = NULL;
1438 unsigned long retval = -EBADF;
1439
1440 audit_mmap_fd(fd, flags);
1441 if (!(flags & MAP_ANONYMOUS)) {
1442 file = fget(fd);
1443 if (!file)
1444 goto out;
1445 }
1446
1447 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1448
1449 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1450
1451 if (file)
1452 fput(file);
1453out:
1454 return retval;
1455}
1456
1457#ifdef __ARCH_WANT_SYS_OLD_MMAP
1458struct mmap_arg_struct {
1459 unsigned long addr;
1460 unsigned long len;
1461 unsigned long prot;
1462 unsigned long flags;
1463 unsigned long fd;
1464 unsigned long offset;
1465};
1466
1467SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1468{
1469 struct mmap_arg_struct a;
1470
1471 if (copy_from_user(&a, arg, sizeof(a)))
1472 return -EFAULT;
1473 if (offset_in_page(a.offset))
1474 return -EINVAL;
1475
1476 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1477 a.offset >> PAGE_SHIFT);
1478}
1479#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1480
1481/*
1482 * split a vma into two pieces at address 'addr', a new vma is allocated either
1483 * for the first part or the tail.
1484 */
1485int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1486 unsigned long addr, int new_below)
1487{
1488 struct vm_area_struct *new;
1489 struct vm_region *region;
1490 unsigned long npages;
1491
1492 /* we're only permitted to split anonymous regions (these should have
1493 * only a single usage on the region) */
1494 if (vma->vm_file)
1495 return -ENOMEM;
1496
1497 if (mm->map_count >= sysctl_max_map_count)
1498 return -ENOMEM;
1499
1500 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1501 if (!region)
1502 return -ENOMEM;
1503
1504 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1505 if (!new) {
1506 kmem_cache_free(vm_region_jar, region);
1507 return -ENOMEM;
1508 }
1509
1510 /* most fields are the same, copy all, and then fixup */
1511 *new = *vma;
1512 *region = *vma->vm_region;
1513 new->vm_region = region;
1514
1515 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1516
1517 if (new_below) {
1518 region->vm_top = region->vm_end = new->vm_end = addr;
1519 } else {
1520 region->vm_start = new->vm_start = addr;
1521 region->vm_pgoff = new->vm_pgoff += npages;
1522 }
1523
1524 if (new->vm_ops && new->vm_ops->open)
1525 new->vm_ops->open(new);
1526
1527 delete_vma_from_mm(vma);
1528 down_write(&nommu_region_sem);
1529 delete_nommu_region(vma->vm_region);
1530 if (new_below) {
1531 vma->vm_region->vm_start = vma->vm_start = addr;
1532 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1533 } else {
1534 vma->vm_region->vm_end = vma->vm_end = addr;
1535 vma->vm_region->vm_top = addr;
1536 }
1537 add_nommu_region(vma->vm_region);
1538 add_nommu_region(new->vm_region);
1539 up_write(&nommu_region_sem);
1540 add_vma_to_mm(mm, vma);
1541 add_vma_to_mm(mm, new);
1542 return 0;
1543}
1544
1545/*
1546 * shrink a VMA by removing the specified chunk from either the beginning or
1547 * the end
1548 */
1549static int shrink_vma(struct mm_struct *mm,
1550 struct vm_area_struct *vma,
1551 unsigned long from, unsigned long to)
1552{
1553 struct vm_region *region;
1554
1555 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1556 * and list */
1557 delete_vma_from_mm(vma);
1558 if (from > vma->vm_start)
1559 vma->vm_end = from;
1560 else
1561 vma->vm_start = to;
1562 add_vma_to_mm(mm, vma);
1563
1564 /* cut the backing region down to size */
1565 region = vma->vm_region;
1566 BUG_ON(region->vm_usage != 1);
1567
1568 down_write(&nommu_region_sem);
1569 delete_nommu_region(region);
1570 if (from > region->vm_start) {
1571 to = region->vm_top;
1572 region->vm_top = region->vm_end = from;
1573 } else {
1574 region->vm_start = to;
1575 }
1576 add_nommu_region(region);
1577 up_write(&nommu_region_sem);
1578
1579 free_page_series(from, to);
1580 return 0;
1581}
1582
1583/*
1584 * release a mapping
1585 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1586 * VMA, though it need not cover the whole VMA
1587 */
1588int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1589{
1590 struct vm_area_struct *vma;
1591 unsigned long end;
1592 int ret;
1593
1594 len = PAGE_ALIGN(len);
1595 if (len == 0)
1596 return -EINVAL;
1597
1598 end = start + len;
1599
1600 /* find the first potentially overlapping VMA */
1601 vma = find_vma(mm, start);
1602 if (!vma) {
1603 static int limit;
1604 if (limit < 5) {
1605 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1606 current->pid, current->comm,
1607 start, start + len - 1);
1608 limit++;
1609 }
1610 return -EINVAL;
1611 }
1612
1613 /* we're allowed to split an anonymous VMA but not a file-backed one */
1614 if (vma->vm_file) {
1615 do {
1616 if (start > vma->vm_start)
1617 return -EINVAL;
1618 if (end == vma->vm_end)
1619 goto erase_whole_vma;
1620 vma = vma->vm_next;
1621 } while (vma);
1622 return -EINVAL;
1623 } else {
1624 /* the chunk must be a subset of the VMA found */
1625 if (start == vma->vm_start && end == vma->vm_end)
1626 goto erase_whole_vma;
1627 if (start < vma->vm_start || end > vma->vm_end)
1628 return -EINVAL;
1629 if (offset_in_page(start))
1630 return -EINVAL;
1631 if (end != vma->vm_end && offset_in_page(end))
1632 return -EINVAL;
1633 if (start != vma->vm_start && end != vma->vm_end) {
1634 ret = split_vma(mm, vma, start, 1);
1635 if (ret < 0)
1636 return ret;
1637 }
1638 return shrink_vma(mm, vma, start, end);
1639 }
1640
1641erase_whole_vma:
1642 delete_vma_from_mm(vma);
1643 delete_vma(mm, vma);
1644 return 0;
1645}
1646EXPORT_SYMBOL(do_munmap);
1647
1648int vm_munmap(unsigned long addr, size_t len)
1649{
1650 struct mm_struct *mm = current->mm;
1651 int ret;
1652
1653 down_write(&mm->mmap_sem);
1654 ret = do_munmap(mm, addr, len);
1655 up_write(&mm->mmap_sem);
1656 return ret;
1657}
1658EXPORT_SYMBOL(vm_munmap);
1659
1660SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1661{
1662 return vm_munmap(addr, len);
1663}
1664
1665/*
1666 * release all the mappings made in a process's VM space
1667 */
1668void exit_mmap(struct mm_struct *mm)
1669{
1670 struct vm_area_struct *vma;
1671
1672 if (!mm)
1673 return;
1674
1675 mm->total_vm = 0;
1676
1677 while ((vma = mm->mmap)) {
1678 mm->mmap = vma->vm_next;
1679 delete_vma_from_mm(vma);
1680 delete_vma(mm, vma);
1681 cond_resched();
1682 }
1683}
1684
1685unsigned long vm_brk(unsigned long addr, unsigned long len)
1686{
1687 return -ENOMEM;
1688}
1689
1690/*
1691 * expand (or shrink) an existing mapping, potentially moving it at the same
1692 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1693 *
1694 * under NOMMU conditions, we only permit changing a mapping's size, and only
1695 * as long as it stays within the region allocated by do_mmap_private() and the
1696 * block is not shareable
1697 *
1698 * MREMAP_FIXED is not supported under NOMMU conditions
1699 */
1700static unsigned long do_mremap(unsigned long addr,
1701 unsigned long old_len, unsigned long new_len,
1702 unsigned long flags, unsigned long new_addr)
1703{
1704 struct vm_area_struct *vma;
1705
1706 /* insanity checks first */
1707 old_len = PAGE_ALIGN(old_len);
1708 new_len = PAGE_ALIGN(new_len);
1709 if (old_len == 0 || new_len == 0)
1710 return (unsigned long) -EINVAL;
1711
1712 if (offset_in_page(addr))
1713 return -EINVAL;
1714
1715 if (flags & MREMAP_FIXED && new_addr != addr)
1716 return (unsigned long) -EINVAL;
1717
1718 vma = find_vma_exact(current->mm, addr, old_len);
1719 if (!vma)
1720 return (unsigned long) -EINVAL;
1721
1722 if (vma->vm_end != vma->vm_start + old_len)
1723 return (unsigned long) -EFAULT;
1724
1725 if (vma->vm_flags & VM_MAYSHARE)
1726 return (unsigned long) -EPERM;
1727
1728 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1729 return (unsigned long) -ENOMEM;
1730
1731 /* all checks complete - do it */
1732 vma->vm_end = vma->vm_start + new_len;
1733 return vma->vm_start;
1734}
1735
1736SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1737 unsigned long, new_len, unsigned long, flags,
1738 unsigned long, new_addr)
1739{
1740 unsigned long ret;
1741
1742 down_write(¤t->mm->mmap_sem);
1743 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1744 up_write(¤t->mm->mmap_sem);
1745 return ret;
1746}
1747
1748struct page *follow_page_mask(struct vm_area_struct *vma,
1749 unsigned long address, unsigned int flags,
1750 unsigned int *page_mask)
1751{
1752 *page_mask = 0;
1753 return NULL;
1754}
1755
1756int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1757 unsigned long pfn, unsigned long size, pgprot_t prot)
1758{
1759 if (addr != (pfn << PAGE_SHIFT))
1760 return -EINVAL;
1761
1762 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1763 return 0;
1764}
1765EXPORT_SYMBOL(remap_pfn_range);
1766
1767int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1768{
1769 unsigned long pfn = start >> PAGE_SHIFT;
1770 unsigned long vm_len = vma->vm_end - vma->vm_start;
1771
1772 pfn += vma->vm_pgoff;
1773 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1774}
1775EXPORT_SYMBOL(vm_iomap_memory);
1776
1777int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1778 unsigned long pgoff)
1779{
1780 unsigned int size = vma->vm_end - vma->vm_start;
1781
1782 if (!(vma->vm_flags & VM_USERMAP))
1783 return -EINVAL;
1784
1785 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1786 vma->vm_end = vma->vm_start + size;
1787
1788 return 0;
1789}
1790EXPORT_SYMBOL(remap_vmalloc_range);
1791
1792unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1793 unsigned long len, unsigned long pgoff, unsigned long flags)
1794{
1795 return -ENOMEM;
1796}
1797
1798void unmap_mapping_range(struct address_space *mapping,
1799 loff_t const holebegin, loff_t const holelen,
1800 int even_cows)
1801{
1802}
1803EXPORT_SYMBOL(unmap_mapping_range);
1804
1805int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1806{
1807 BUG();
1808 return 0;
1809}
1810EXPORT_SYMBOL(filemap_fault);
1811
1812void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
1813{
1814 BUG();
1815}
1816EXPORT_SYMBOL(filemap_map_pages);
1817
1818static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1819 unsigned long addr, void *buf, int len, int write)
1820{
1821 struct vm_area_struct *vma;
1822
1823 down_read(&mm->mmap_sem);
1824
1825 /* the access must start within one of the target process's mappings */
1826 vma = find_vma(mm, addr);
1827 if (vma) {
1828 /* don't overrun this mapping */
1829 if (addr + len >= vma->vm_end)
1830 len = vma->vm_end - addr;
1831
1832 /* only read or write mappings where it is permitted */
1833 if (write && vma->vm_flags & VM_MAYWRITE)
1834 copy_to_user_page(vma, NULL, addr,
1835 (void *) addr, buf, len);
1836 else if (!write && vma->vm_flags & VM_MAYREAD)
1837 copy_from_user_page(vma, NULL, addr,
1838 buf, (void *) addr, len);
1839 else
1840 len = 0;
1841 } else {
1842 len = 0;
1843 }
1844
1845 up_read(&mm->mmap_sem);
1846
1847 return len;
1848}
1849
1850/**
1851 * @access_remote_vm - access another process' address space
1852 * @mm: the mm_struct of the target address space
1853 * @addr: start address to access
1854 * @buf: source or destination buffer
1855 * @len: number of bytes to transfer
1856 * @write: whether the access is a write
1857 *
1858 * The caller must hold a reference on @mm.
1859 */
1860int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1861 void *buf, int len, int write)
1862{
1863 return __access_remote_vm(NULL, mm, addr, buf, len, write);
1864}
1865
1866/*
1867 * Access another process' address space.
1868 * - source/target buffer must be kernel space
1869 */
1870int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1871{
1872 struct mm_struct *mm;
1873
1874 if (addr + len < addr)
1875 return 0;
1876
1877 mm = get_task_mm(tsk);
1878 if (!mm)
1879 return 0;
1880
1881 len = __access_remote_vm(tsk, mm, addr, buf, len, write);
1882
1883 mmput(mm);
1884 return len;
1885}
1886
1887/**
1888 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1889 * @inode: The inode to check
1890 * @size: The current filesize of the inode
1891 * @newsize: The proposed filesize of the inode
1892 *
1893 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1894 * make sure that that any outstanding VMAs aren't broken and then shrink the
1895 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1896 * automatically grant mappings that are too large.
1897 */
1898int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1899 size_t newsize)
1900{
1901 struct vm_area_struct *vma;
1902 struct vm_region *region;
1903 pgoff_t low, high;
1904 size_t r_size, r_top;
1905
1906 low = newsize >> PAGE_SHIFT;
1907 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1908
1909 down_write(&nommu_region_sem);
1910 i_mmap_lock_read(inode->i_mapping);
1911
1912 /* search for VMAs that fall within the dead zone */
1913 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1914 /* found one - only interested if it's shared out of the page
1915 * cache */
1916 if (vma->vm_flags & VM_SHARED) {
1917 i_mmap_unlock_read(inode->i_mapping);
1918 up_write(&nommu_region_sem);
1919 return -ETXTBSY; /* not quite true, but near enough */
1920 }
1921 }
1922
1923 /* reduce any regions that overlap the dead zone - if in existence,
1924 * these will be pointed to by VMAs that don't overlap the dead zone
1925 *
1926 * we don't check for any regions that start beyond the EOF as there
1927 * shouldn't be any
1928 */
1929 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1930 if (!(vma->vm_flags & VM_SHARED))
1931 continue;
1932
1933 region = vma->vm_region;
1934 r_size = region->vm_top - region->vm_start;
1935 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1936
1937 if (r_top > newsize) {
1938 region->vm_top -= r_top - newsize;
1939 if (region->vm_end > region->vm_top)
1940 region->vm_end = region->vm_top;
1941 }
1942 }
1943
1944 i_mmap_unlock_read(inode->i_mapping);
1945 up_write(&nommu_region_sem);
1946 return 0;
1947}
1948
1949/*
1950 * Initialise sysctl_user_reserve_kbytes.
1951 *
1952 * This is intended to prevent a user from starting a single memory hogging
1953 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1954 * mode.
1955 *
1956 * The default value is min(3% of free memory, 128MB)
1957 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1958 */
1959static int __meminit init_user_reserve(void)
1960{
1961 unsigned long free_kbytes;
1962
1963 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1964
1965 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1966 return 0;
1967}
1968subsys_initcall(init_user_reserve);
1969
1970/*
1971 * Initialise sysctl_admin_reserve_kbytes.
1972 *
1973 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1974 * to log in and kill a memory hogging process.
1975 *
1976 * Systems with more than 256MB will reserve 8MB, enough to recover
1977 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1978 * only reserve 3% of free pages by default.
1979 */
1980static int __meminit init_admin_reserve(void)
1981{
1982 unsigned long free_kbytes;
1983
1984 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1985
1986 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1987 return 0;
1988}
1989subsys_initcall(init_admin_reserve);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/nommu.c
4 *
5 * Replacement code for mm functions to support CPU's that don't
6 * have any form of memory management unit (thus no virtual memory).
7 *
8 * See Documentation/admin-guide/mm/nommu-mmap.rst
9 *
10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/export.h>
20#include <linux/mm.h>
21#include <linux/sched/mm.h>
22#include <linux/mman.h>
23#include <linux/swap.h>
24#include <linux/file.h>
25#include <linux/highmem.h>
26#include <linux/pagemap.h>
27#include <linux/slab.h>
28#include <linux/vmalloc.h>
29#include <linux/backing-dev.h>
30#include <linux/compiler.h>
31#include <linux/mount.h>
32#include <linux/personality.h>
33#include <linux/security.h>
34#include <linux/syscalls.h>
35#include <linux/audit.h>
36#include <linux/printk.h>
37
38#include <linux/uaccess.h>
39#include <linux/uio.h>
40#include <asm/tlb.h>
41#include <asm/tlbflush.h>
42#include <asm/mmu_context.h>
43#include "internal.h"
44
45void *high_memory;
46EXPORT_SYMBOL(high_memory);
47struct page *mem_map;
48unsigned long max_mapnr;
49EXPORT_SYMBOL(max_mapnr);
50unsigned long highest_memmap_pfn;
51int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
52int heap_stack_gap = 0;
53
54atomic_long_t mmap_pages_allocated;
55
56EXPORT_SYMBOL(mem_map);
57
58/* list of mapped, potentially shareable regions */
59static struct kmem_cache *vm_region_jar;
60struct rb_root nommu_region_tree = RB_ROOT;
61DECLARE_RWSEM(nommu_region_sem);
62
63const struct vm_operations_struct generic_file_vm_ops = {
64};
65
66/*
67 * Return the total memory allocated for this pointer, not
68 * just what the caller asked for.
69 *
70 * Doesn't have to be accurate, i.e. may have races.
71 */
72unsigned int kobjsize(const void *objp)
73{
74 struct page *page;
75
76 /*
77 * If the object we have should not have ksize performed on it,
78 * return size of 0
79 */
80 if (!objp || !virt_addr_valid(objp))
81 return 0;
82
83 page = virt_to_head_page(objp);
84
85 /*
86 * If the allocator sets PageSlab, we know the pointer came from
87 * kmalloc().
88 */
89 if (PageSlab(page))
90 return ksize(objp);
91
92 /*
93 * If it's not a compound page, see if we have a matching VMA
94 * region. This test is intentionally done in reverse order,
95 * so if there's no VMA, we still fall through and hand back
96 * PAGE_SIZE for 0-order pages.
97 */
98 if (!PageCompound(page)) {
99 struct vm_area_struct *vma;
100
101 vma = find_vma(current->mm, (unsigned long)objp);
102 if (vma)
103 return vma->vm_end - vma->vm_start;
104 }
105
106 /*
107 * The ksize() function is only guaranteed to work for pointers
108 * returned by kmalloc(). So handle arbitrary pointers here.
109 */
110 return page_size(page);
111}
112
113void vfree(const void *addr)
114{
115 kfree(addr);
116}
117EXPORT_SYMBOL(vfree);
118
119void *__vmalloc_noprof(unsigned long size, gfp_t gfp_mask)
120{
121 /*
122 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
123 * returns only a logical address.
124 */
125 return kmalloc_noprof(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
126}
127EXPORT_SYMBOL(__vmalloc_noprof);
128
129void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
130{
131 return krealloc_noprof(p, size, (flags | __GFP_COMP) & ~__GFP_HIGHMEM);
132}
133
134void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
135 unsigned long start, unsigned long end, gfp_t gfp_mask,
136 pgprot_t prot, unsigned long vm_flags, int node,
137 const void *caller)
138{
139 return __vmalloc_noprof(size, gfp_mask);
140}
141
142void *__vmalloc_node_noprof(unsigned long size, unsigned long align, gfp_t gfp_mask,
143 int node, const void *caller)
144{
145 return __vmalloc_noprof(size, gfp_mask);
146}
147
148static void *__vmalloc_user_flags(unsigned long size, gfp_t flags)
149{
150 void *ret;
151
152 ret = __vmalloc(size, flags);
153 if (ret) {
154 struct vm_area_struct *vma;
155
156 mmap_write_lock(current->mm);
157 vma = find_vma(current->mm, (unsigned long)ret);
158 if (vma)
159 vm_flags_set(vma, VM_USERMAP);
160 mmap_write_unlock(current->mm);
161 }
162
163 return ret;
164}
165
166void *vmalloc_user_noprof(unsigned long size)
167{
168 return __vmalloc_user_flags(size, GFP_KERNEL | __GFP_ZERO);
169}
170EXPORT_SYMBOL(vmalloc_user_noprof);
171
172struct page *vmalloc_to_page(const void *addr)
173{
174 return virt_to_page(addr);
175}
176EXPORT_SYMBOL(vmalloc_to_page);
177
178unsigned long vmalloc_to_pfn(const void *addr)
179{
180 return page_to_pfn(virt_to_page(addr));
181}
182EXPORT_SYMBOL(vmalloc_to_pfn);
183
184long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
185{
186 /* Don't allow overflow */
187 if ((unsigned long) addr + count < count)
188 count = -(unsigned long) addr;
189
190 return copy_to_iter(addr, count, iter);
191}
192
193/*
194 * vmalloc - allocate virtually contiguous memory
195 *
196 * @size: allocation size
197 *
198 * Allocate enough pages to cover @size from the page level
199 * allocator and map them into contiguous kernel virtual space.
200 *
201 * For tight control over page level allocator and protection flags
202 * use __vmalloc() instead.
203 */
204void *vmalloc_noprof(unsigned long size)
205{
206 return __vmalloc_noprof(size, GFP_KERNEL);
207}
208EXPORT_SYMBOL(vmalloc_noprof);
209
210void *vmalloc_huge_noprof(unsigned long size, gfp_t gfp_mask) __weak __alias(__vmalloc_noprof);
211
212/*
213 * vzalloc - allocate virtually contiguous memory with zero fill
214 *
215 * @size: allocation size
216 *
217 * Allocate enough pages to cover @size from the page level
218 * allocator and map them into contiguous kernel virtual space.
219 * The memory allocated is set to zero.
220 *
221 * For tight control over page level allocator and protection flags
222 * use __vmalloc() instead.
223 */
224void *vzalloc_noprof(unsigned long size)
225{
226 return __vmalloc_noprof(size, GFP_KERNEL | __GFP_ZERO);
227}
228EXPORT_SYMBOL(vzalloc_noprof);
229
230/**
231 * vmalloc_node - allocate memory on a specific node
232 * @size: allocation size
233 * @node: numa node
234 *
235 * Allocate enough pages to cover @size from the page level
236 * allocator and map them into contiguous kernel virtual space.
237 *
238 * For tight control over page level allocator and protection flags
239 * use __vmalloc() instead.
240 */
241void *vmalloc_node_noprof(unsigned long size, int node)
242{
243 return vmalloc_noprof(size);
244}
245EXPORT_SYMBOL(vmalloc_node_noprof);
246
247/**
248 * vzalloc_node - allocate memory on a specific node with zero fill
249 * @size: allocation size
250 * @node: numa node
251 *
252 * Allocate enough pages to cover @size from the page level
253 * allocator and map them into contiguous kernel virtual space.
254 * The memory allocated is set to zero.
255 *
256 * For tight control over page level allocator and protection flags
257 * use __vmalloc() instead.
258 */
259void *vzalloc_node_noprof(unsigned long size, int node)
260{
261 return vzalloc_noprof(size);
262}
263EXPORT_SYMBOL(vzalloc_node_noprof);
264
265/**
266 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
267 * @size: allocation size
268 *
269 * Allocate enough 32bit PA addressable pages to cover @size from the
270 * page level allocator and map them into contiguous kernel virtual space.
271 */
272void *vmalloc_32_noprof(unsigned long size)
273{
274 return __vmalloc_noprof(size, GFP_KERNEL);
275}
276EXPORT_SYMBOL(vmalloc_32_noprof);
277
278/**
279 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
280 * @size: allocation size
281 *
282 * The resulting memory area is 32bit addressable and zeroed so it can be
283 * mapped to userspace without leaking data.
284 *
285 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
286 * remap_vmalloc_range() are permissible.
287 */
288void *vmalloc_32_user_noprof(unsigned long size)
289{
290 /*
291 * We'll have to sort out the ZONE_DMA bits for 64-bit,
292 * but for now this can simply use vmalloc_user() directly.
293 */
294 return vmalloc_user_noprof(size);
295}
296EXPORT_SYMBOL(vmalloc_32_user_noprof);
297
298void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
299{
300 BUG();
301 return NULL;
302}
303EXPORT_SYMBOL(vmap);
304
305void vunmap(const void *addr)
306{
307 BUG();
308}
309EXPORT_SYMBOL(vunmap);
310
311void *vm_map_ram(struct page **pages, unsigned int count, int node)
312{
313 BUG();
314 return NULL;
315}
316EXPORT_SYMBOL(vm_map_ram);
317
318void vm_unmap_ram(const void *mem, unsigned int count)
319{
320 BUG();
321}
322EXPORT_SYMBOL(vm_unmap_ram);
323
324void vm_unmap_aliases(void)
325{
326}
327EXPORT_SYMBOL_GPL(vm_unmap_aliases);
328
329void free_vm_area(struct vm_struct *area)
330{
331 BUG();
332}
333EXPORT_SYMBOL_GPL(free_vm_area);
334
335int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
336 struct page *page)
337{
338 return -EINVAL;
339}
340EXPORT_SYMBOL(vm_insert_page);
341
342int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
343 struct page **pages, unsigned long *num)
344{
345 return -EINVAL;
346}
347EXPORT_SYMBOL(vm_insert_pages);
348
349int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
350 unsigned long num)
351{
352 return -EINVAL;
353}
354EXPORT_SYMBOL(vm_map_pages);
355
356int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
357 unsigned long num)
358{
359 return -EINVAL;
360}
361EXPORT_SYMBOL(vm_map_pages_zero);
362
363/*
364 * sys_brk() for the most part doesn't need the global kernel
365 * lock, except when an application is doing something nasty
366 * like trying to un-brk an area that has already been mapped
367 * to a regular file. in this case, the unmapping will need
368 * to invoke file system routines that need the global lock.
369 */
370SYSCALL_DEFINE1(brk, unsigned long, brk)
371{
372 struct mm_struct *mm = current->mm;
373
374 if (brk < mm->start_brk || brk > mm->context.end_brk)
375 return mm->brk;
376
377 if (mm->brk == brk)
378 return mm->brk;
379
380 /*
381 * Always allow shrinking brk
382 */
383 if (brk <= mm->brk) {
384 mm->brk = brk;
385 return brk;
386 }
387
388 /*
389 * Ok, looks good - let it rip.
390 */
391 flush_icache_user_range(mm->brk, brk);
392 return mm->brk = brk;
393}
394
395/*
396 * initialise the percpu counter for VM and region record slabs
397 */
398void __init mmap_init(void)
399{
400 int ret;
401
402 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
403 VM_BUG_ON(ret);
404 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
405}
406
407/*
408 * validate the region tree
409 * - the caller must hold the region lock
410 */
411#ifdef CONFIG_DEBUG_NOMMU_REGIONS
412static noinline void validate_nommu_regions(void)
413{
414 struct vm_region *region, *last;
415 struct rb_node *p, *lastp;
416
417 lastp = rb_first(&nommu_region_tree);
418 if (!lastp)
419 return;
420
421 last = rb_entry(lastp, struct vm_region, vm_rb);
422 BUG_ON(last->vm_end <= last->vm_start);
423 BUG_ON(last->vm_top < last->vm_end);
424
425 while ((p = rb_next(lastp))) {
426 region = rb_entry(p, struct vm_region, vm_rb);
427 last = rb_entry(lastp, struct vm_region, vm_rb);
428
429 BUG_ON(region->vm_end <= region->vm_start);
430 BUG_ON(region->vm_top < region->vm_end);
431 BUG_ON(region->vm_start < last->vm_top);
432
433 lastp = p;
434 }
435}
436#else
437static void validate_nommu_regions(void)
438{
439}
440#endif
441
442/*
443 * add a region into the global tree
444 */
445static void add_nommu_region(struct vm_region *region)
446{
447 struct vm_region *pregion;
448 struct rb_node **p, *parent;
449
450 validate_nommu_regions();
451
452 parent = NULL;
453 p = &nommu_region_tree.rb_node;
454 while (*p) {
455 parent = *p;
456 pregion = rb_entry(parent, struct vm_region, vm_rb);
457 if (region->vm_start < pregion->vm_start)
458 p = &(*p)->rb_left;
459 else if (region->vm_start > pregion->vm_start)
460 p = &(*p)->rb_right;
461 else if (pregion == region)
462 return;
463 else
464 BUG();
465 }
466
467 rb_link_node(®ion->vm_rb, parent, p);
468 rb_insert_color(®ion->vm_rb, &nommu_region_tree);
469
470 validate_nommu_regions();
471}
472
473/*
474 * delete a region from the global tree
475 */
476static void delete_nommu_region(struct vm_region *region)
477{
478 BUG_ON(!nommu_region_tree.rb_node);
479
480 validate_nommu_regions();
481 rb_erase(®ion->vm_rb, &nommu_region_tree);
482 validate_nommu_regions();
483}
484
485/*
486 * free a contiguous series of pages
487 */
488static void free_page_series(unsigned long from, unsigned long to)
489{
490 for (; from < to; from += PAGE_SIZE) {
491 struct page *page = virt_to_page((void *)from);
492
493 atomic_long_dec(&mmap_pages_allocated);
494 put_page(page);
495 }
496}
497
498/*
499 * release a reference to a region
500 * - the caller must hold the region semaphore for writing, which this releases
501 * - the region may not have been added to the tree yet, in which case vm_top
502 * will equal vm_start
503 */
504static void __put_nommu_region(struct vm_region *region)
505 __releases(nommu_region_sem)
506{
507 BUG_ON(!nommu_region_tree.rb_node);
508
509 if (--region->vm_usage == 0) {
510 if (region->vm_top > region->vm_start)
511 delete_nommu_region(region);
512 up_write(&nommu_region_sem);
513
514 if (region->vm_file)
515 fput(region->vm_file);
516
517 /* IO memory and memory shared directly out of the pagecache
518 * from ramfs/tmpfs mustn't be released here */
519 if (region->vm_flags & VM_MAPPED_COPY)
520 free_page_series(region->vm_start, region->vm_top);
521 kmem_cache_free(vm_region_jar, region);
522 } else {
523 up_write(&nommu_region_sem);
524 }
525}
526
527/*
528 * release a reference to a region
529 */
530static void put_nommu_region(struct vm_region *region)
531{
532 down_write(&nommu_region_sem);
533 __put_nommu_region(region);
534}
535
536static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
537{
538 vma->vm_mm = mm;
539
540 /* add the VMA to the mapping */
541 if (vma->vm_file) {
542 struct address_space *mapping = vma->vm_file->f_mapping;
543
544 i_mmap_lock_write(mapping);
545 flush_dcache_mmap_lock(mapping);
546 vma_interval_tree_insert(vma, &mapping->i_mmap);
547 flush_dcache_mmap_unlock(mapping);
548 i_mmap_unlock_write(mapping);
549 }
550}
551
552static void cleanup_vma_from_mm(struct vm_area_struct *vma)
553{
554 vma->vm_mm->map_count--;
555 /* remove the VMA from the mapping */
556 if (vma->vm_file) {
557 struct address_space *mapping;
558 mapping = vma->vm_file->f_mapping;
559
560 i_mmap_lock_write(mapping);
561 flush_dcache_mmap_lock(mapping);
562 vma_interval_tree_remove(vma, &mapping->i_mmap);
563 flush_dcache_mmap_unlock(mapping);
564 i_mmap_unlock_write(mapping);
565 }
566}
567
568/*
569 * delete a VMA from its owning mm_struct and address space
570 */
571static int delete_vma_from_mm(struct vm_area_struct *vma)
572{
573 VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start);
574
575 vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
576 if (vma_iter_prealloc(&vmi, NULL)) {
577 pr_warn("Allocation of vma tree for process %d failed\n",
578 current->pid);
579 return -ENOMEM;
580 }
581 cleanup_vma_from_mm(vma);
582
583 /* remove from the MM's tree and list */
584 vma_iter_clear(&vmi);
585 return 0;
586}
587/*
588 * destroy a VMA record
589 */
590static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
591{
592 vma_close(vma);
593 if (vma->vm_file)
594 fput(vma->vm_file);
595 put_nommu_region(vma->vm_region);
596 vm_area_free(vma);
597}
598
599struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
600 unsigned long start_addr,
601 unsigned long end_addr)
602{
603 unsigned long index = start_addr;
604
605 mmap_assert_locked(mm);
606 return mt_find(&mm->mm_mt, &index, end_addr - 1);
607}
608EXPORT_SYMBOL(find_vma_intersection);
609
610/*
611 * look up the first VMA in which addr resides, NULL if none
612 * - should be called with mm->mmap_lock at least held readlocked
613 */
614struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
615{
616 VMA_ITERATOR(vmi, mm, addr);
617
618 return vma_iter_load(&vmi);
619}
620EXPORT_SYMBOL(find_vma);
621
622/*
623 * At least xtensa ends up having protection faults even with no
624 * MMU.. No stack expansion, at least.
625 */
626struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
627 unsigned long addr, struct pt_regs *regs)
628{
629 struct vm_area_struct *vma;
630
631 mmap_read_lock(mm);
632 vma = vma_lookup(mm, addr);
633 if (!vma)
634 mmap_read_unlock(mm);
635 return vma;
636}
637
638/*
639 * expand a stack to a given address
640 * - not supported under NOMMU conditions
641 */
642int expand_stack_locked(struct vm_area_struct *vma, unsigned long addr)
643{
644 return -ENOMEM;
645}
646
647struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
648{
649 mmap_read_unlock(mm);
650 return NULL;
651}
652
653/*
654 * look up the first VMA exactly that exactly matches addr
655 * - should be called with mm->mmap_lock at least held readlocked
656 */
657static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
658 unsigned long addr,
659 unsigned long len)
660{
661 struct vm_area_struct *vma;
662 unsigned long end = addr + len;
663 VMA_ITERATOR(vmi, mm, addr);
664
665 vma = vma_iter_load(&vmi);
666 if (!vma)
667 return NULL;
668 if (vma->vm_start != addr)
669 return NULL;
670 if (vma->vm_end != end)
671 return NULL;
672
673 return vma;
674}
675
676/*
677 * determine whether a mapping should be permitted and, if so, what sort of
678 * mapping we're capable of supporting
679 */
680static int validate_mmap_request(struct file *file,
681 unsigned long addr,
682 unsigned long len,
683 unsigned long prot,
684 unsigned long flags,
685 unsigned long pgoff,
686 unsigned long *_capabilities)
687{
688 unsigned long capabilities, rlen;
689 int ret;
690
691 /* do the simple checks first */
692 if (flags & MAP_FIXED)
693 return -EINVAL;
694
695 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
696 (flags & MAP_TYPE) != MAP_SHARED)
697 return -EINVAL;
698
699 if (!len)
700 return -EINVAL;
701
702 /* Careful about overflows.. */
703 rlen = PAGE_ALIGN(len);
704 if (!rlen || rlen > TASK_SIZE)
705 return -ENOMEM;
706
707 /* offset overflow? */
708 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
709 return -EOVERFLOW;
710
711 if (file) {
712 /* files must support mmap */
713 if (!file->f_op->mmap)
714 return -ENODEV;
715
716 /* work out if what we've got could possibly be shared
717 * - we support chardevs that provide their own "memory"
718 * - we support files/blockdevs that are memory backed
719 */
720 if (file->f_op->mmap_capabilities) {
721 capabilities = file->f_op->mmap_capabilities(file);
722 } else {
723 /* no explicit capabilities set, so assume some
724 * defaults */
725 switch (file_inode(file)->i_mode & S_IFMT) {
726 case S_IFREG:
727 case S_IFBLK:
728 capabilities = NOMMU_MAP_COPY;
729 break;
730
731 case S_IFCHR:
732 capabilities =
733 NOMMU_MAP_DIRECT |
734 NOMMU_MAP_READ |
735 NOMMU_MAP_WRITE;
736 break;
737
738 default:
739 return -EINVAL;
740 }
741 }
742
743 /* eliminate any capabilities that we can't support on this
744 * device */
745 if (!file->f_op->get_unmapped_area)
746 capabilities &= ~NOMMU_MAP_DIRECT;
747 if (!(file->f_mode & FMODE_CAN_READ))
748 capabilities &= ~NOMMU_MAP_COPY;
749
750 /* The file shall have been opened with read permission. */
751 if (!(file->f_mode & FMODE_READ))
752 return -EACCES;
753
754 if (flags & MAP_SHARED) {
755 /* do checks for writing, appending and locking */
756 if ((prot & PROT_WRITE) &&
757 !(file->f_mode & FMODE_WRITE))
758 return -EACCES;
759
760 if (IS_APPEND(file_inode(file)) &&
761 (file->f_mode & FMODE_WRITE))
762 return -EACCES;
763
764 if (!(capabilities & NOMMU_MAP_DIRECT))
765 return -ENODEV;
766
767 /* we mustn't privatise shared mappings */
768 capabilities &= ~NOMMU_MAP_COPY;
769 } else {
770 /* we're going to read the file into private memory we
771 * allocate */
772 if (!(capabilities & NOMMU_MAP_COPY))
773 return -ENODEV;
774
775 /* we don't permit a private writable mapping to be
776 * shared with the backing device */
777 if (prot & PROT_WRITE)
778 capabilities &= ~NOMMU_MAP_DIRECT;
779 }
780
781 if (capabilities & NOMMU_MAP_DIRECT) {
782 if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) ||
783 ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
784 ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC))
785 ) {
786 capabilities &= ~NOMMU_MAP_DIRECT;
787 if (flags & MAP_SHARED) {
788 pr_warn("MAP_SHARED not completely supported on !MMU\n");
789 return -EINVAL;
790 }
791 }
792 }
793
794 /* handle executable mappings and implied executable
795 * mappings */
796 if (path_noexec(&file->f_path)) {
797 if (prot & PROT_EXEC)
798 return -EPERM;
799 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
800 /* handle implication of PROT_EXEC by PROT_READ */
801 if (current->personality & READ_IMPLIES_EXEC) {
802 if (capabilities & NOMMU_MAP_EXEC)
803 prot |= PROT_EXEC;
804 }
805 } else if ((prot & PROT_READ) &&
806 (prot & PROT_EXEC) &&
807 !(capabilities & NOMMU_MAP_EXEC)
808 ) {
809 /* backing file is not executable, try to copy */
810 capabilities &= ~NOMMU_MAP_DIRECT;
811 }
812 } else {
813 /* anonymous mappings are always memory backed and can be
814 * privately mapped
815 */
816 capabilities = NOMMU_MAP_COPY;
817
818 /* handle PROT_EXEC implication by PROT_READ */
819 if ((prot & PROT_READ) &&
820 (current->personality & READ_IMPLIES_EXEC))
821 prot |= PROT_EXEC;
822 }
823
824 /* allow the security API to have its say */
825 ret = security_mmap_addr(addr);
826 if (ret < 0)
827 return ret;
828
829 /* looks okay */
830 *_capabilities = capabilities;
831 return 0;
832}
833
834/*
835 * we've determined that we can make the mapping, now translate what we
836 * now know into VMA flags
837 */
838static unsigned long determine_vm_flags(struct file *file,
839 unsigned long prot,
840 unsigned long flags,
841 unsigned long capabilities)
842{
843 unsigned long vm_flags;
844
845 vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(file, flags);
846
847 if (!file) {
848 /*
849 * MAP_ANONYMOUS. MAP_SHARED is mapped to MAP_PRIVATE, because
850 * there is no fork().
851 */
852 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
853 } else if (flags & MAP_PRIVATE) {
854 /* MAP_PRIVATE file mapping */
855 if (capabilities & NOMMU_MAP_DIRECT)
856 vm_flags |= (capabilities & NOMMU_VMFLAGS);
857 else
858 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
859
860 if (!(prot & PROT_WRITE) && !current->ptrace)
861 /*
862 * R/O private file mapping which cannot be used to
863 * modify memory, especially also not via active ptrace
864 * (e.g., set breakpoints) or later by upgrading
865 * permissions (no mprotect()). We can try overlaying
866 * the file mapping, which will work e.g., on chardevs,
867 * ramfs/tmpfs/shmfs and romfs/cramf.
868 */
869 vm_flags |= VM_MAYOVERLAY;
870 } else {
871 /* MAP_SHARED file mapping: NOMMU_MAP_DIRECT is set. */
872 vm_flags |= VM_SHARED | VM_MAYSHARE |
873 (capabilities & NOMMU_VMFLAGS);
874 }
875
876 return vm_flags;
877}
878
879/*
880 * set up a shared mapping on a file (the driver or filesystem provides and
881 * pins the storage)
882 */
883static int do_mmap_shared_file(struct vm_area_struct *vma)
884{
885 int ret;
886
887 ret = mmap_file(vma->vm_file, vma);
888 if (ret == 0) {
889 vma->vm_region->vm_top = vma->vm_region->vm_end;
890 return 0;
891 }
892 if (ret != -ENOSYS)
893 return ret;
894
895 /* getting -ENOSYS indicates that direct mmap isn't possible (as
896 * opposed to tried but failed) so we can only give a suitable error as
897 * it's not possible to make a private copy if MAP_SHARED was given */
898 return -ENODEV;
899}
900
901/*
902 * set up a private mapping or an anonymous shared mapping
903 */
904static int do_mmap_private(struct vm_area_struct *vma,
905 struct vm_region *region,
906 unsigned long len,
907 unsigned long capabilities)
908{
909 unsigned long total, point;
910 void *base;
911 int ret, order;
912
913 /*
914 * Invoke the file's mapping function so that it can keep track of
915 * shared mappings on devices or memory. VM_MAYOVERLAY will be set if
916 * it may attempt to share, which will make is_nommu_shared_mapping()
917 * happy.
918 */
919 if (capabilities & NOMMU_MAP_DIRECT) {
920 ret = mmap_file(vma->vm_file, vma);
921 /* shouldn't return success if we're not sharing */
922 if (WARN_ON_ONCE(!is_nommu_shared_mapping(vma->vm_flags)))
923 ret = -ENOSYS;
924 if (ret == 0) {
925 vma->vm_region->vm_top = vma->vm_region->vm_end;
926 return 0;
927 }
928 if (ret != -ENOSYS)
929 return ret;
930
931 /* getting an ENOSYS error indicates that direct mmap isn't
932 * possible (as opposed to tried but failed) so we'll try to
933 * make a private copy of the data and map that instead */
934 }
935
936
937 /* allocate some memory to hold the mapping
938 * - note that this may not return a page-aligned address if the object
939 * we're allocating is smaller than a page
940 */
941 order = get_order(len);
942 total = 1 << order;
943 point = len >> PAGE_SHIFT;
944
945 /* we don't want to allocate a power-of-2 sized page set */
946 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
947 total = point;
948
949 base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
950 if (!base)
951 goto enomem;
952
953 atomic_long_add(total, &mmap_pages_allocated);
954
955 vm_flags_set(vma, VM_MAPPED_COPY);
956 region->vm_flags = vma->vm_flags;
957 region->vm_start = (unsigned long) base;
958 region->vm_end = region->vm_start + len;
959 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
960
961 vma->vm_start = region->vm_start;
962 vma->vm_end = region->vm_start + len;
963
964 if (vma->vm_file) {
965 /* read the contents of a file into the copy */
966 loff_t fpos;
967
968 fpos = vma->vm_pgoff;
969 fpos <<= PAGE_SHIFT;
970
971 ret = kernel_read(vma->vm_file, base, len, &fpos);
972 if (ret < 0)
973 goto error_free;
974
975 /* clear the last little bit */
976 if (ret < len)
977 memset(base + ret, 0, len - ret);
978
979 } else {
980 vma_set_anonymous(vma);
981 }
982
983 return 0;
984
985error_free:
986 free_page_series(region->vm_start, region->vm_top);
987 region->vm_start = vma->vm_start = 0;
988 region->vm_end = vma->vm_end = 0;
989 region->vm_top = 0;
990 return ret;
991
992enomem:
993 pr_err("Allocation of length %lu from process %d (%s) failed\n",
994 len, current->pid, current->comm);
995 show_mem();
996 return -ENOMEM;
997}
998
999/*
1000 * handle mapping creation for uClinux
1001 */
1002unsigned long do_mmap(struct file *file,
1003 unsigned long addr,
1004 unsigned long len,
1005 unsigned long prot,
1006 unsigned long flags,
1007 vm_flags_t vm_flags,
1008 unsigned long pgoff,
1009 unsigned long *populate,
1010 struct list_head *uf)
1011{
1012 struct vm_area_struct *vma;
1013 struct vm_region *region;
1014 struct rb_node *rb;
1015 unsigned long capabilities, result;
1016 int ret;
1017 VMA_ITERATOR(vmi, current->mm, 0);
1018
1019 *populate = 0;
1020
1021 /* decide whether we should attempt the mapping, and if so what sort of
1022 * mapping */
1023 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1024 &capabilities);
1025 if (ret < 0)
1026 return ret;
1027
1028 /* we ignore the address hint */
1029 addr = 0;
1030 len = PAGE_ALIGN(len);
1031
1032 /* we've determined that we can make the mapping, now translate what we
1033 * now know into VMA flags */
1034 vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1035
1036
1037 /* we're going to need to record the mapping */
1038 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1039 if (!region)
1040 goto error_getting_region;
1041
1042 vma = vm_area_alloc(current->mm);
1043 if (!vma)
1044 goto error_getting_vma;
1045
1046 region->vm_usage = 1;
1047 region->vm_flags = vm_flags;
1048 region->vm_pgoff = pgoff;
1049
1050 vm_flags_init(vma, vm_flags);
1051 vma->vm_pgoff = pgoff;
1052
1053 if (file) {
1054 region->vm_file = get_file(file);
1055 vma->vm_file = get_file(file);
1056 }
1057
1058 down_write(&nommu_region_sem);
1059
1060 /* if we want to share, we need to check for regions created by other
1061 * mmap() calls that overlap with our proposed mapping
1062 * - we can only share with a superset match on most regular files
1063 * - shared mappings on character devices and memory backed files are
1064 * permitted to overlap inexactly as far as we are concerned for in
1065 * these cases, sharing is handled in the driver or filesystem rather
1066 * than here
1067 */
1068 if (is_nommu_shared_mapping(vm_flags)) {
1069 struct vm_region *pregion;
1070 unsigned long pglen, rpglen, pgend, rpgend, start;
1071
1072 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1073 pgend = pgoff + pglen;
1074
1075 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1076 pregion = rb_entry(rb, struct vm_region, vm_rb);
1077
1078 if (!is_nommu_shared_mapping(pregion->vm_flags))
1079 continue;
1080
1081 /* search for overlapping mappings on the same file */
1082 if (file_inode(pregion->vm_file) !=
1083 file_inode(file))
1084 continue;
1085
1086 if (pregion->vm_pgoff >= pgend)
1087 continue;
1088
1089 rpglen = pregion->vm_end - pregion->vm_start;
1090 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1091 rpgend = pregion->vm_pgoff + rpglen;
1092 if (pgoff >= rpgend)
1093 continue;
1094
1095 /* handle inexactly overlapping matches between
1096 * mappings */
1097 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1098 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1099 /* new mapping is not a subset of the region */
1100 if (!(capabilities & NOMMU_MAP_DIRECT))
1101 goto sharing_violation;
1102 continue;
1103 }
1104
1105 /* we've found a region we can share */
1106 pregion->vm_usage++;
1107 vma->vm_region = pregion;
1108 start = pregion->vm_start;
1109 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1110 vma->vm_start = start;
1111 vma->vm_end = start + len;
1112
1113 if (pregion->vm_flags & VM_MAPPED_COPY)
1114 vm_flags_set(vma, VM_MAPPED_COPY);
1115 else {
1116 ret = do_mmap_shared_file(vma);
1117 if (ret < 0) {
1118 vma->vm_region = NULL;
1119 vma->vm_start = 0;
1120 vma->vm_end = 0;
1121 pregion->vm_usage--;
1122 pregion = NULL;
1123 goto error_just_free;
1124 }
1125 }
1126 fput(region->vm_file);
1127 kmem_cache_free(vm_region_jar, region);
1128 region = pregion;
1129 result = start;
1130 goto share;
1131 }
1132
1133 /* obtain the address at which to make a shared mapping
1134 * - this is the hook for quasi-memory character devices to
1135 * tell us the location of a shared mapping
1136 */
1137 if (capabilities & NOMMU_MAP_DIRECT) {
1138 addr = file->f_op->get_unmapped_area(file, addr, len,
1139 pgoff, flags);
1140 if (IS_ERR_VALUE(addr)) {
1141 ret = addr;
1142 if (ret != -ENOSYS)
1143 goto error_just_free;
1144
1145 /* the driver refused to tell us where to site
1146 * the mapping so we'll have to attempt to copy
1147 * it */
1148 ret = -ENODEV;
1149 if (!(capabilities & NOMMU_MAP_COPY))
1150 goto error_just_free;
1151
1152 capabilities &= ~NOMMU_MAP_DIRECT;
1153 } else {
1154 vma->vm_start = region->vm_start = addr;
1155 vma->vm_end = region->vm_end = addr + len;
1156 }
1157 }
1158 }
1159
1160 vma->vm_region = region;
1161
1162 /* set up the mapping
1163 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1164 */
1165 if (file && vma->vm_flags & VM_SHARED)
1166 ret = do_mmap_shared_file(vma);
1167 else
1168 ret = do_mmap_private(vma, region, len, capabilities);
1169 if (ret < 0)
1170 goto error_just_free;
1171 add_nommu_region(region);
1172
1173 /* clear anonymous mappings that don't ask for uninitialized data */
1174 if (!vma->vm_file &&
1175 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
1176 !(flags & MAP_UNINITIALIZED)))
1177 memset((void *)region->vm_start, 0,
1178 region->vm_end - region->vm_start);
1179
1180 /* okay... we have a mapping; now we have to register it */
1181 result = vma->vm_start;
1182
1183 current->mm->total_vm += len >> PAGE_SHIFT;
1184
1185share:
1186 BUG_ON(!vma->vm_region);
1187 vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
1188 if (vma_iter_prealloc(&vmi, vma))
1189 goto error_just_free;
1190
1191 setup_vma_to_mm(vma, current->mm);
1192 current->mm->map_count++;
1193 /* add the VMA to the tree */
1194 vma_iter_store(&vmi, vma);
1195
1196 /* we flush the region from the icache only when the first executable
1197 * mapping of it is made */
1198 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1199 flush_icache_user_range(region->vm_start, region->vm_end);
1200 region->vm_icache_flushed = true;
1201 }
1202
1203 up_write(&nommu_region_sem);
1204
1205 return result;
1206
1207error_just_free:
1208 up_write(&nommu_region_sem);
1209error:
1210 vma_iter_free(&vmi);
1211 if (region->vm_file)
1212 fput(region->vm_file);
1213 kmem_cache_free(vm_region_jar, region);
1214 if (vma->vm_file)
1215 fput(vma->vm_file);
1216 vm_area_free(vma);
1217 return ret;
1218
1219sharing_violation:
1220 up_write(&nommu_region_sem);
1221 pr_warn("Attempt to share mismatched mappings\n");
1222 ret = -EINVAL;
1223 goto error;
1224
1225error_getting_vma:
1226 kmem_cache_free(vm_region_jar, region);
1227 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1228 len, current->pid);
1229 show_mem();
1230 return -ENOMEM;
1231
1232error_getting_region:
1233 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1234 len, current->pid);
1235 show_mem();
1236 return -ENOMEM;
1237}
1238
1239unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1240 unsigned long prot, unsigned long flags,
1241 unsigned long fd, unsigned long pgoff)
1242{
1243 struct file *file = NULL;
1244 unsigned long retval = -EBADF;
1245
1246 audit_mmap_fd(fd, flags);
1247 if (!(flags & MAP_ANONYMOUS)) {
1248 file = fget(fd);
1249 if (!file)
1250 goto out;
1251 }
1252
1253 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1254
1255 if (file)
1256 fput(file);
1257out:
1258 return retval;
1259}
1260
1261SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1262 unsigned long, prot, unsigned long, flags,
1263 unsigned long, fd, unsigned long, pgoff)
1264{
1265 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1266}
1267
1268#ifdef __ARCH_WANT_SYS_OLD_MMAP
1269struct mmap_arg_struct {
1270 unsigned long addr;
1271 unsigned long len;
1272 unsigned long prot;
1273 unsigned long flags;
1274 unsigned long fd;
1275 unsigned long offset;
1276};
1277
1278SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1279{
1280 struct mmap_arg_struct a;
1281
1282 if (copy_from_user(&a, arg, sizeof(a)))
1283 return -EFAULT;
1284 if (offset_in_page(a.offset))
1285 return -EINVAL;
1286
1287 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1288 a.offset >> PAGE_SHIFT);
1289}
1290#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1291
1292/*
1293 * split a vma into two pieces at address 'addr', a new vma is allocated either
1294 * for the first part or the tail.
1295 */
1296static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
1297 unsigned long addr, int new_below)
1298{
1299 struct vm_area_struct *new;
1300 struct vm_region *region;
1301 unsigned long npages;
1302 struct mm_struct *mm;
1303
1304 /* we're only permitted to split anonymous regions (these should have
1305 * only a single usage on the region) */
1306 if (vma->vm_file)
1307 return -ENOMEM;
1308
1309 mm = vma->vm_mm;
1310 if (mm->map_count >= sysctl_max_map_count)
1311 return -ENOMEM;
1312
1313 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1314 if (!region)
1315 return -ENOMEM;
1316
1317 new = vm_area_dup(vma);
1318 if (!new)
1319 goto err_vma_dup;
1320
1321 /* most fields are the same, copy all, and then fixup */
1322 *region = *vma->vm_region;
1323 new->vm_region = region;
1324
1325 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1326
1327 if (new_below) {
1328 region->vm_top = region->vm_end = new->vm_end = addr;
1329 } else {
1330 region->vm_start = new->vm_start = addr;
1331 region->vm_pgoff = new->vm_pgoff += npages;
1332 }
1333
1334 vma_iter_config(vmi, new->vm_start, new->vm_end);
1335 if (vma_iter_prealloc(vmi, vma)) {
1336 pr_warn("Allocation of vma tree for process %d failed\n",
1337 current->pid);
1338 goto err_vmi_preallocate;
1339 }
1340
1341 if (new->vm_ops && new->vm_ops->open)
1342 new->vm_ops->open(new);
1343
1344 down_write(&nommu_region_sem);
1345 delete_nommu_region(vma->vm_region);
1346 if (new_below) {
1347 vma->vm_region->vm_start = vma->vm_start = addr;
1348 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1349 } else {
1350 vma->vm_region->vm_end = vma->vm_end = addr;
1351 vma->vm_region->vm_top = addr;
1352 }
1353 add_nommu_region(vma->vm_region);
1354 add_nommu_region(new->vm_region);
1355 up_write(&nommu_region_sem);
1356
1357 setup_vma_to_mm(vma, mm);
1358 setup_vma_to_mm(new, mm);
1359 vma_iter_store(vmi, new);
1360 mm->map_count++;
1361 return 0;
1362
1363err_vmi_preallocate:
1364 vm_area_free(new);
1365err_vma_dup:
1366 kmem_cache_free(vm_region_jar, region);
1367 return -ENOMEM;
1368}
1369
1370/*
1371 * shrink a VMA by removing the specified chunk from either the beginning or
1372 * the end
1373 */
1374static int vmi_shrink_vma(struct vma_iterator *vmi,
1375 struct vm_area_struct *vma,
1376 unsigned long from, unsigned long to)
1377{
1378 struct vm_region *region;
1379
1380 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1381 * and list */
1382 if (from > vma->vm_start) {
1383 if (vma_iter_clear_gfp(vmi, from, vma->vm_end, GFP_KERNEL))
1384 return -ENOMEM;
1385 vma->vm_end = from;
1386 } else {
1387 if (vma_iter_clear_gfp(vmi, vma->vm_start, to, GFP_KERNEL))
1388 return -ENOMEM;
1389 vma->vm_start = to;
1390 }
1391
1392 /* cut the backing region down to size */
1393 region = vma->vm_region;
1394 BUG_ON(region->vm_usage != 1);
1395
1396 down_write(&nommu_region_sem);
1397 delete_nommu_region(region);
1398 if (from > region->vm_start) {
1399 to = region->vm_top;
1400 region->vm_top = region->vm_end = from;
1401 } else {
1402 region->vm_start = to;
1403 }
1404 add_nommu_region(region);
1405 up_write(&nommu_region_sem);
1406
1407 free_page_series(from, to);
1408 return 0;
1409}
1410
1411/*
1412 * release a mapping
1413 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1414 * VMA, though it need not cover the whole VMA
1415 */
1416int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
1417{
1418 VMA_ITERATOR(vmi, mm, start);
1419 struct vm_area_struct *vma;
1420 unsigned long end;
1421 int ret = 0;
1422
1423 len = PAGE_ALIGN(len);
1424 if (len == 0)
1425 return -EINVAL;
1426
1427 end = start + len;
1428
1429 /* find the first potentially overlapping VMA */
1430 vma = vma_find(&vmi, end);
1431 if (!vma) {
1432 static int limit;
1433 if (limit < 5) {
1434 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1435 current->pid, current->comm,
1436 start, start + len - 1);
1437 limit++;
1438 }
1439 return -EINVAL;
1440 }
1441
1442 /* we're allowed to split an anonymous VMA but not a file-backed one */
1443 if (vma->vm_file) {
1444 do {
1445 if (start > vma->vm_start)
1446 return -EINVAL;
1447 if (end == vma->vm_end)
1448 goto erase_whole_vma;
1449 vma = vma_find(&vmi, end);
1450 } while (vma);
1451 return -EINVAL;
1452 } else {
1453 /* the chunk must be a subset of the VMA found */
1454 if (start == vma->vm_start && end == vma->vm_end)
1455 goto erase_whole_vma;
1456 if (start < vma->vm_start || end > vma->vm_end)
1457 return -EINVAL;
1458 if (offset_in_page(start))
1459 return -EINVAL;
1460 if (end != vma->vm_end && offset_in_page(end))
1461 return -EINVAL;
1462 if (start != vma->vm_start && end != vma->vm_end) {
1463 ret = split_vma(&vmi, vma, start, 1);
1464 if (ret < 0)
1465 return ret;
1466 }
1467 return vmi_shrink_vma(&vmi, vma, start, end);
1468 }
1469
1470erase_whole_vma:
1471 if (delete_vma_from_mm(vma))
1472 ret = -ENOMEM;
1473 else
1474 delete_vma(mm, vma);
1475 return ret;
1476}
1477
1478int vm_munmap(unsigned long addr, size_t len)
1479{
1480 struct mm_struct *mm = current->mm;
1481 int ret;
1482
1483 mmap_write_lock(mm);
1484 ret = do_munmap(mm, addr, len, NULL);
1485 mmap_write_unlock(mm);
1486 return ret;
1487}
1488EXPORT_SYMBOL(vm_munmap);
1489
1490SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1491{
1492 return vm_munmap(addr, len);
1493}
1494
1495/*
1496 * release all the mappings made in a process's VM space
1497 */
1498void exit_mmap(struct mm_struct *mm)
1499{
1500 VMA_ITERATOR(vmi, mm, 0);
1501 struct vm_area_struct *vma;
1502
1503 if (!mm)
1504 return;
1505
1506 mm->total_vm = 0;
1507
1508 /*
1509 * Lock the mm to avoid assert complaining even though this is the only
1510 * user of the mm
1511 */
1512 mmap_write_lock(mm);
1513 for_each_vma(vmi, vma) {
1514 cleanup_vma_from_mm(vma);
1515 delete_vma(mm, vma);
1516 cond_resched();
1517 }
1518 __mt_destroy(&mm->mm_mt);
1519 mmap_write_unlock(mm);
1520}
1521
1522/*
1523 * expand (or shrink) an existing mapping, potentially moving it at the same
1524 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1525 *
1526 * under NOMMU conditions, we only permit changing a mapping's size, and only
1527 * as long as it stays within the region allocated by do_mmap_private() and the
1528 * block is not shareable
1529 *
1530 * MREMAP_FIXED is not supported under NOMMU conditions
1531 */
1532static unsigned long do_mremap(unsigned long addr,
1533 unsigned long old_len, unsigned long new_len,
1534 unsigned long flags, unsigned long new_addr)
1535{
1536 struct vm_area_struct *vma;
1537
1538 /* insanity checks first */
1539 old_len = PAGE_ALIGN(old_len);
1540 new_len = PAGE_ALIGN(new_len);
1541 if (old_len == 0 || new_len == 0)
1542 return (unsigned long) -EINVAL;
1543
1544 if (offset_in_page(addr))
1545 return -EINVAL;
1546
1547 if (flags & MREMAP_FIXED && new_addr != addr)
1548 return (unsigned long) -EINVAL;
1549
1550 vma = find_vma_exact(current->mm, addr, old_len);
1551 if (!vma)
1552 return (unsigned long) -EINVAL;
1553
1554 if (vma->vm_end != vma->vm_start + old_len)
1555 return (unsigned long) -EFAULT;
1556
1557 if (is_nommu_shared_mapping(vma->vm_flags))
1558 return (unsigned long) -EPERM;
1559
1560 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1561 return (unsigned long) -ENOMEM;
1562
1563 /* all checks complete - do it */
1564 vma->vm_end = vma->vm_start + new_len;
1565 return vma->vm_start;
1566}
1567
1568SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1569 unsigned long, new_len, unsigned long, flags,
1570 unsigned long, new_addr)
1571{
1572 unsigned long ret;
1573
1574 mmap_write_lock(current->mm);
1575 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1576 mmap_write_unlock(current->mm);
1577 return ret;
1578}
1579
1580int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1581 unsigned long pfn, unsigned long size, pgprot_t prot)
1582{
1583 if (addr != (pfn << PAGE_SHIFT))
1584 return -EINVAL;
1585
1586 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
1587 return 0;
1588}
1589EXPORT_SYMBOL(remap_pfn_range);
1590
1591int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1592{
1593 unsigned long pfn = start >> PAGE_SHIFT;
1594 unsigned long vm_len = vma->vm_end - vma->vm_start;
1595
1596 pfn += vma->vm_pgoff;
1597 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1598}
1599EXPORT_SYMBOL(vm_iomap_memory);
1600
1601int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1602 unsigned long pgoff)
1603{
1604 unsigned int size = vma->vm_end - vma->vm_start;
1605
1606 if (!(vma->vm_flags & VM_USERMAP))
1607 return -EINVAL;
1608
1609 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1610 vma->vm_end = vma->vm_start + size;
1611
1612 return 0;
1613}
1614EXPORT_SYMBOL(remap_vmalloc_range);
1615
1616vm_fault_t filemap_fault(struct vm_fault *vmf)
1617{
1618 BUG();
1619 return 0;
1620}
1621EXPORT_SYMBOL(filemap_fault);
1622
1623vm_fault_t filemap_map_pages(struct vm_fault *vmf,
1624 pgoff_t start_pgoff, pgoff_t end_pgoff)
1625{
1626 BUG();
1627 return 0;
1628}
1629EXPORT_SYMBOL(filemap_map_pages);
1630
1631static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
1632 void *buf, int len, unsigned int gup_flags)
1633{
1634 struct vm_area_struct *vma;
1635 int write = gup_flags & FOLL_WRITE;
1636
1637 if (mmap_read_lock_killable(mm))
1638 return 0;
1639
1640 /* the access must start within one of the target process's mappings */
1641 vma = find_vma(mm, addr);
1642 if (vma) {
1643 /* don't overrun this mapping */
1644 if (addr + len >= vma->vm_end)
1645 len = vma->vm_end - addr;
1646
1647 /* only read or write mappings where it is permitted */
1648 if (write && vma->vm_flags & VM_MAYWRITE)
1649 copy_to_user_page(vma, NULL, addr,
1650 (void *) addr, buf, len);
1651 else if (!write && vma->vm_flags & VM_MAYREAD)
1652 copy_from_user_page(vma, NULL, addr,
1653 buf, (void *) addr, len);
1654 else
1655 len = 0;
1656 } else {
1657 len = 0;
1658 }
1659
1660 mmap_read_unlock(mm);
1661
1662 return len;
1663}
1664
1665/**
1666 * access_remote_vm - access another process' address space
1667 * @mm: the mm_struct of the target address space
1668 * @addr: start address to access
1669 * @buf: source or destination buffer
1670 * @len: number of bytes to transfer
1671 * @gup_flags: flags modifying lookup behaviour
1672 *
1673 * The caller must hold a reference on @mm.
1674 */
1675int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1676 void *buf, int len, unsigned int gup_flags)
1677{
1678 return __access_remote_vm(mm, addr, buf, len, gup_flags);
1679}
1680
1681/*
1682 * Access another process' address space.
1683 * - source/target buffer must be kernel space
1684 */
1685int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
1686 unsigned int gup_flags)
1687{
1688 struct mm_struct *mm;
1689
1690 if (addr + len < addr)
1691 return 0;
1692
1693 mm = get_task_mm(tsk);
1694 if (!mm)
1695 return 0;
1696
1697 len = __access_remote_vm(mm, addr, buf, len, gup_flags);
1698
1699 mmput(mm);
1700 return len;
1701}
1702EXPORT_SYMBOL_GPL(access_process_vm);
1703
1704/**
1705 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1706 * @inode: The inode to check
1707 * @size: The current filesize of the inode
1708 * @newsize: The proposed filesize of the inode
1709 *
1710 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1711 * make sure that any outstanding VMAs aren't broken and then shrink the
1712 * vm_regions that extend beyond so that do_mmap() doesn't
1713 * automatically grant mappings that are too large.
1714 */
1715int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1716 size_t newsize)
1717{
1718 struct vm_area_struct *vma;
1719 struct vm_region *region;
1720 pgoff_t low, high;
1721 size_t r_size, r_top;
1722
1723 low = newsize >> PAGE_SHIFT;
1724 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1725
1726 down_write(&nommu_region_sem);
1727 i_mmap_lock_read(inode->i_mapping);
1728
1729 /* search for VMAs that fall within the dead zone */
1730 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1731 /* found one - only interested if it's shared out of the page
1732 * cache */
1733 if (vma->vm_flags & VM_SHARED) {
1734 i_mmap_unlock_read(inode->i_mapping);
1735 up_write(&nommu_region_sem);
1736 return -ETXTBSY; /* not quite true, but near enough */
1737 }
1738 }
1739
1740 /* reduce any regions that overlap the dead zone - if in existence,
1741 * these will be pointed to by VMAs that don't overlap the dead zone
1742 *
1743 * we don't check for any regions that start beyond the EOF as there
1744 * shouldn't be any
1745 */
1746 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1747 if (!(vma->vm_flags & VM_SHARED))
1748 continue;
1749
1750 region = vma->vm_region;
1751 r_size = region->vm_top - region->vm_start;
1752 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1753
1754 if (r_top > newsize) {
1755 region->vm_top -= r_top - newsize;
1756 if (region->vm_end > region->vm_top)
1757 region->vm_end = region->vm_top;
1758 }
1759 }
1760
1761 i_mmap_unlock_read(inode->i_mapping);
1762 up_write(&nommu_region_sem);
1763 return 0;
1764}
1765
1766/*
1767 * Initialise sysctl_user_reserve_kbytes.
1768 *
1769 * This is intended to prevent a user from starting a single memory hogging
1770 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1771 * mode.
1772 *
1773 * The default value is min(3% of free memory, 128MB)
1774 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1775 */
1776static int __meminit init_user_reserve(void)
1777{
1778 unsigned long free_kbytes;
1779
1780 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1781
1782 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1783 return 0;
1784}
1785subsys_initcall(init_user_reserve);
1786
1787/*
1788 * Initialise sysctl_admin_reserve_kbytes.
1789 *
1790 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1791 * to log in and kill a memory hogging process.
1792 *
1793 * Systems with more than 256MB will reserve 8MB, enough to recover
1794 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1795 * only reserve 3% of free pages by default.
1796 */
1797static int __meminit init_admin_reserve(void)
1798{
1799 unsigned long free_kbytes;
1800
1801 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1802
1803 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1804 return 0;
1805}
1806subsys_initcall(init_admin_reserve);