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