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