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