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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/mmap.c
4 *
5 * Written by obz.
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/backing-dev.h>
15#include <linux/mm.h>
16#include <linux/mm_inline.h>
17#include <linux/shm.h>
18#include <linux/mman.h>
19#include <linux/pagemap.h>
20#include <linux/swap.h>
21#include <linux/syscalls.h>
22#include <linux/capability.h>
23#include <linux/init.h>
24#include <linux/file.h>
25#include <linux/fs.h>
26#include <linux/personality.h>
27#include <linux/security.h>
28#include <linux/hugetlb.h>
29#include <linux/shmem_fs.h>
30#include <linux/profile.h>
31#include <linux/export.h>
32#include <linux/mount.h>
33#include <linux/mempolicy.h>
34#include <linux/rmap.h>
35#include <linux/mmu_notifier.h>
36#include <linux/mmdebug.h>
37#include <linux/perf_event.h>
38#include <linux/audit.h>
39#include <linux/khugepaged.h>
40#include <linux/uprobes.h>
41#include <linux/notifier.h>
42#include <linux/memory.h>
43#include <linux/printk.h>
44#include <linux/userfaultfd_k.h>
45#include <linux/moduleparam.h>
46#include <linux/pkeys.h>
47#include <linux/oom.h>
48#include <linux/sched/mm.h>
49#include <linux/ksm.h>
50#include <linux/memfd.h>
51
52#include <linux/uaccess.h>
53#include <asm/cacheflush.h>
54#include <asm/tlb.h>
55#include <asm/mmu_context.h>
56
57#define CREATE_TRACE_POINTS
58#include <trace/events/mmap.h>
59
60#include "internal.h"
61
62#ifndef arch_mmap_check
63#define arch_mmap_check(addr, len, flags) (0)
64#endif
65
66#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
67const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
68int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX;
69int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
70#endif
71#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
72const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
73const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
74int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
75#endif
76
77static bool ignore_rlimit_data;
78core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
79
80/* Update vma->vm_page_prot to reflect vma->vm_flags. */
81void vma_set_page_prot(struct vm_area_struct *vma)
82{
83 unsigned long vm_flags = vma->vm_flags;
84 pgprot_t vm_page_prot;
85
86 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
87 if (vma_wants_writenotify(vma, vm_page_prot)) {
88 vm_flags &= ~VM_SHARED;
89 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
90 }
91 /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
92 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
93}
94
95/*
96 * check_brk_limits() - Use platform specific check of range & verify mlock
97 * limits.
98 * @addr: The address to check
99 * @len: The size of increase.
100 *
101 * Return: 0 on success.
102 */
103static int check_brk_limits(unsigned long addr, unsigned long len)
104{
105 unsigned long mapped_addr;
106
107 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
108 if (IS_ERR_VALUE(mapped_addr))
109 return mapped_addr;
110
111 return mlock_future_ok(current->mm, current->mm->def_flags, len)
112 ? 0 : -EAGAIN;
113}
114static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
115 unsigned long addr, unsigned long request, unsigned long flags);
116SYSCALL_DEFINE1(brk, unsigned long, brk)
117{
118 unsigned long newbrk, oldbrk, origbrk;
119 struct mm_struct *mm = current->mm;
120 struct vm_area_struct *brkvma, *next = NULL;
121 unsigned long min_brk;
122 bool populate = false;
123 LIST_HEAD(uf);
124 struct vma_iterator vmi;
125
126 if (mmap_write_lock_killable(mm))
127 return -EINTR;
128
129 origbrk = mm->brk;
130
131#ifdef CONFIG_COMPAT_BRK
132 /*
133 * CONFIG_COMPAT_BRK can still be overridden by setting
134 * randomize_va_space to 2, which will still cause mm->start_brk
135 * to be arbitrarily shifted
136 */
137 if (current->brk_randomized)
138 min_brk = mm->start_brk;
139 else
140 min_brk = mm->end_data;
141#else
142 min_brk = mm->start_brk;
143#endif
144 if (brk < min_brk)
145 goto out;
146
147 /*
148 * Check against rlimit here. If this check is done later after the test
149 * of oldbrk with newbrk then it can escape the test and let the data
150 * segment grow beyond its set limit the in case where the limit is
151 * not page aligned -Ram Gupta
152 */
153 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
154 mm->end_data, mm->start_data))
155 goto out;
156
157 newbrk = PAGE_ALIGN(brk);
158 oldbrk = PAGE_ALIGN(mm->brk);
159 if (oldbrk == newbrk) {
160 mm->brk = brk;
161 goto success;
162 }
163
164 /* Always allow shrinking brk. */
165 if (brk <= mm->brk) {
166 /* Search one past newbrk */
167 vma_iter_init(&vmi, mm, newbrk);
168 brkvma = vma_find(&vmi, oldbrk);
169 if (!brkvma || brkvma->vm_start >= oldbrk)
170 goto out; /* mapping intersects with an existing non-brk vma. */
171 /*
172 * mm->brk must be protected by write mmap_lock.
173 * do_vmi_align_munmap() will drop the lock on success, so
174 * update it before calling do_vma_munmap().
175 */
176 mm->brk = brk;
177 if (do_vmi_align_munmap(&vmi, brkvma, mm, newbrk, oldbrk, &uf,
178 /* unlock = */ true))
179 goto out;
180
181 goto success_unlocked;
182 }
183
184 if (check_brk_limits(oldbrk, newbrk - oldbrk))
185 goto out;
186
187 /*
188 * Only check if the next VMA is within the stack_guard_gap of the
189 * expansion area
190 */
191 vma_iter_init(&vmi, mm, oldbrk);
192 next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
193 if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
194 goto out;
195
196 brkvma = vma_prev_limit(&vmi, mm->start_brk);
197 /* Ok, looks good - let it rip. */
198 if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
199 goto out;
200
201 mm->brk = brk;
202 if (mm->def_flags & VM_LOCKED)
203 populate = true;
204
205success:
206 mmap_write_unlock(mm);
207success_unlocked:
208 userfaultfd_unmap_complete(mm, &uf);
209 if (populate)
210 mm_populate(oldbrk, newbrk - oldbrk);
211 return brk;
212
213out:
214 mm->brk = origbrk;
215 mmap_write_unlock(mm);
216 return origbrk;
217}
218
219/*
220 * If a hint addr is less than mmap_min_addr change hint to be as
221 * low as possible but still greater than mmap_min_addr
222 */
223static inline unsigned long round_hint_to_min(unsigned long hint)
224{
225 hint &= PAGE_MASK;
226 if (((void *)hint != NULL) &&
227 (hint < mmap_min_addr))
228 return PAGE_ALIGN(mmap_min_addr);
229 return hint;
230}
231
232bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
233 unsigned long bytes)
234{
235 unsigned long locked_pages, limit_pages;
236
237 if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
238 return true;
239
240 locked_pages = bytes >> PAGE_SHIFT;
241 locked_pages += mm->locked_vm;
242
243 limit_pages = rlimit(RLIMIT_MEMLOCK);
244 limit_pages >>= PAGE_SHIFT;
245
246 return locked_pages <= limit_pages;
247}
248
249static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
250{
251 if (S_ISREG(inode->i_mode))
252 return MAX_LFS_FILESIZE;
253
254 if (S_ISBLK(inode->i_mode))
255 return MAX_LFS_FILESIZE;
256
257 if (S_ISSOCK(inode->i_mode))
258 return MAX_LFS_FILESIZE;
259
260 /* Special "we do even unsigned file positions" case */
261 if (file->f_op->fop_flags & FOP_UNSIGNED_OFFSET)
262 return 0;
263
264 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
265 return ULONG_MAX;
266}
267
268static inline bool file_mmap_ok(struct file *file, struct inode *inode,
269 unsigned long pgoff, unsigned long len)
270{
271 u64 maxsize = file_mmap_size_max(file, inode);
272
273 if (maxsize && len > maxsize)
274 return false;
275 maxsize -= len;
276 if (pgoff > maxsize >> PAGE_SHIFT)
277 return false;
278 return true;
279}
280
281/*
282 * The caller must write-lock current->mm->mmap_lock.
283 */
284unsigned long do_mmap(struct file *file, unsigned long addr,
285 unsigned long len, unsigned long prot,
286 unsigned long flags, vm_flags_t vm_flags,
287 unsigned long pgoff, unsigned long *populate,
288 struct list_head *uf)
289{
290 struct mm_struct *mm = current->mm;
291 int pkey = 0;
292
293 *populate = 0;
294
295 if (!len)
296 return -EINVAL;
297
298 /*
299 * Does the application expect PROT_READ to imply PROT_EXEC?
300 *
301 * (the exception is when the underlying filesystem is noexec
302 * mounted, in which case we don't add PROT_EXEC.)
303 */
304 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
305 if (!(file && path_noexec(&file->f_path)))
306 prot |= PROT_EXEC;
307
308 /* force arch specific MAP_FIXED handling in get_unmapped_area */
309 if (flags & MAP_FIXED_NOREPLACE)
310 flags |= MAP_FIXED;
311
312 if (!(flags & MAP_FIXED))
313 addr = round_hint_to_min(addr);
314
315 /* Careful about overflows.. */
316 len = PAGE_ALIGN(len);
317 if (!len)
318 return -ENOMEM;
319
320 /* offset overflow? */
321 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
322 return -EOVERFLOW;
323
324 /* Too many mappings? */
325 if (mm->map_count > sysctl_max_map_count)
326 return -ENOMEM;
327
328 /*
329 * addr is returned from get_unmapped_area,
330 * There are two cases:
331 * 1> MAP_FIXED == false
332 * unallocated memory, no need to check sealing.
333 * 1> MAP_FIXED == true
334 * sealing is checked inside mmap_region when
335 * do_vmi_munmap is called.
336 */
337
338 if (prot == PROT_EXEC) {
339 pkey = execute_only_pkey(mm);
340 if (pkey < 0)
341 pkey = 0;
342 }
343
344 /* Do simple checking here so the lower-level routines won't have
345 * to. we assume access permissions have been handled by the open
346 * of the memory object, so we don't do any here.
347 */
348 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(file, flags) |
349 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
350
351 /* Obtain the address to map to. we verify (or select) it and ensure
352 * that it represents a valid section of the address space.
353 */
354 addr = __get_unmapped_area(file, addr, len, pgoff, flags, vm_flags);
355 if (IS_ERR_VALUE(addr))
356 return addr;
357
358 if (flags & MAP_FIXED_NOREPLACE) {
359 if (find_vma_intersection(mm, addr, addr + len))
360 return -EEXIST;
361 }
362
363 if (flags & MAP_LOCKED)
364 if (!can_do_mlock())
365 return -EPERM;
366
367 if (!mlock_future_ok(mm, vm_flags, len))
368 return -EAGAIN;
369
370 if (file) {
371 struct inode *inode = file_inode(file);
372 unsigned int seals = memfd_file_seals(file);
373 unsigned long flags_mask;
374
375 if (!file_mmap_ok(file, inode, pgoff, len))
376 return -EOVERFLOW;
377
378 flags_mask = LEGACY_MAP_MASK;
379 if (file->f_op->fop_flags & FOP_MMAP_SYNC)
380 flags_mask |= MAP_SYNC;
381
382 switch (flags & MAP_TYPE) {
383 case MAP_SHARED:
384 /*
385 * Force use of MAP_SHARED_VALIDATE with non-legacy
386 * flags. E.g. MAP_SYNC is dangerous to use with
387 * MAP_SHARED as you don't know which consistency model
388 * you will get. We silently ignore unsupported flags
389 * with MAP_SHARED to preserve backward compatibility.
390 */
391 flags &= LEGACY_MAP_MASK;
392 fallthrough;
393 case MAP_SHARED_VALIDATE:
394 if (flags & ~flags_mask)
395 return -EOPNOTSUPP;
396 if (prot & PROT_WRITE) {
397 if (!(file->f_mode & FMODE_WRITE))
398 return -EACCES;
399 if (IS_SWAPFILE(file->f_mapping->host))
400 return -ETXTBSY;
401 }
402
403 /*
404 * Make sure we don't allow writing to an append-only
405 * file..
406 */
407 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
408 return -EACCES;
409
410 vm_flags |= VM_SHARED | VM_MAYSHARE;
411 if (!(file->f_mode & FMODE_WRITE))
412 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
413 else if (is_readonly_sealed(seals, vm_flags))
414 vm_flags &= ~VM_MAYWRITE;
415 fallthrough;
416 case MAP_PRIVATE:
417 if (!(file->f_mode & FMODE_READ))
418 return -EACCES;
419 if (path_noexec(&file->f_path)) {
420 if (vm_flags & VM_EXEC)
421 return -EPERM;
422 vm_flags &= ~VM_MAYEXEC;
423 }
424
425 if (!file->f_op->mmap)
426 return -ENODEV;
427 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
428 return -EINVAL;
429 break;
430
431 default:
432 return -EINVAL;
433 }
434 } else {
435 switch (flags & MAP_TYPE) {
436 case MAP_SHARED:
437 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
438 return -EINVAL;
439 /*
440 * Ignore pgoff.
441 */
442 pgoff = 0;
443 vm_flags |= VM_SHARED | VM_MAYSHARE;
444 break;
445 case MAP_DROPPABLE:
446 if (VM_DROPPABLE == VM_NONE)
447 return -ENOTSUPP;
448 /*
449 * A locked or stack area makes no sense to be droppable.
450 *
451 * Also, since droppable pages can just go away at any time
452 * it makes no sense to copy them on fork or dump them.
453 *
454 * And don't attempt to combine with hugetlb for now.
455 */
456 if (flags & (MAP_LOCKED | MAP_HUGETLB))
457 return -EINVAL;
458 if (vm_flags & (VM_GROWSDOWN | VM_GROWSUP))
459 return -EINVAL;
460
461 vm_flags |= VM_DROPPABLE;
462
463 /*
464 * If the pages can be dropped, then it doesn't make
465 * sense to reserve them.
466 */
467 vm_flags |= VM_NORESERVE;
468
469 /*
470 * Likewise, they're volatile enough that they
471 * shouldn't survive forks or coredumps.
472 */
473 vm_flags |= VM_WIPEONFORK | VM_DONTDUMP;
474 fallthrough;
475 case MAP_PRIVATE:
476 /*
477 * Set pgoff according to addr for anon_vma.
478 */
479 pgoff = addr >> PAGE_SHIFT;
480 break;
481 default:
482 return -EINVAL;
483 }
484 }
485
486 /*
487 * Set 'VM_NORESERVE' if we should not account for the
488 * memory use of this mapping.
489 */
490 if (flags & MAP_NORESERVE) {
491 /* We honor MAP_NORESERVE if allowed to overcommit */
492 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
493 vm_flags |= VM_NORESERVE;
494
495 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
496 if (file && is_file_hugepages(file))
497 vm_flags |= VM_NORESERVE;
498 }
499
500 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
501 if (!IS_ERR_VALUE(addr) &&
502 ((vm_flags & VM_LOCKED) ||
503 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
504 *populate = len;
505 return addr;
506}
507
508unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
509 unsigned long prot, unsigned long flags,
510 unsigned long fd, unsigned long pgoff)
511{
512 struct file *file = NULL;
513 unsigned long retval;
514
515 if (!(flags & MAP_ANONYMOUS)) {
516 audit_mmap_fd(fd, flags);
517 file = fget(fd);
518 if (!file)
519 return -EBADF;
520 if (is_file_hugepages(file)) {
521 len = ALIGN(len, huge_page_size(hstate_file(file)));
522 } else if (unlikely(flags & MAP_HUGETLB)) {
523 retval = -EINVAL;
524 goto out_fput;
525 }
526 } else if (flags & MAP_HUGETLB) {
527 struct hstate *hs;
528
529 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
530 if (!hs)
531 return -EINVAL;
532
533 len = ALIGN(len, huge_page_size(hs));
534 /*
535 * VM_NORESERVE is used because the reservations will be
536 * taken when vm_ops->mmap() is called
537 */
538 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
539 VM_NORESERVE,
540 HUGETLB_ANONHUGE_INODE,
541 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
542 if (IS_ERR(file))
543 return PTR_ERR(file);
544 }
545
546 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
547out_fput:
548 if (file)
549 fput(file);
550 return retval;
551}
552
553SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
554 unsigned long, prot, unsigned long, flags,
555 unsigned long, fd, unsigned long, pgoff)
556{
557 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
558}
559
560#ifdef __ARCH_WANT_SYS_OLD_MMAP
561struct mmap_arg_struct {
562 unsigned long addr;
563 unsigned long len;
564 unsigned long prot;
565 unsigned long flags;
566 unsigned long fd;
567 unsigned long offset;
568};
569
570SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
571{
572 struct mmap_arg_struct a;
573
574 if (copy_from_user(&a, arg, sizeof(a)))
575 return -EFAULT;
576 if (offset_in_page(a.offset))
577 return -EINVAL;
578
579 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
580 a.offset >> PAGE_SHIFT);
581}
582#endif /* __ARCH_WANT_SYS_OLD_MMAP */
583
584/**
585 * unmapped_area() - Find an area between the low_limit and the high_limit with
586 * the correct alignment and offset, all from @info. Note: current->mm is used
587 * for the search.
588 *
589 * @info: The unmapped area information including the range [low_limit -
590 * high_limit), the alignment offset and mask.
591 *
592 * Return: A memory address or -ENOMEM.
593 */
594static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
595{
596 unsigned long length, gap;
597 unsigned long low_limit, high_limit;
598 struct vm_area_struct *tmp;
599 VMA_ITERATOR(vmi, current->mm, 0);
600
601 /* Adjust search length to account for worst case alignment overhead */
602 length = info->length + info->align_mask + info->start_gap;
603 if (length < info->length)
604 return -ENOMEM;
605
606 low_limit = info->low_limit;
607 if (low_limit < mmap_min_addr)
608 low_limit = mmap_min_addr;
609 high_limit = info->high_limit;
610retry:
611 if (vma_iter_area_lowest(&vmi, low_limit, high_limit, length))
612 return -ENOMEM;
613
614 /*
615 * Adjust for the gap first so it doesn't interfere with the
616 * later alignment. The first step is the minimum needed to
617 * fulill the start gap, the next steps is the minimum to align
618 * that. It is the minimum needed to fulill both.
619 */
620 gap = vma_iter_addr(&vmi) + info->start_gap;
621 gap += (info->align_offset - gap) & info->align_mask;
622 tmp = vma_next(&vmi);
623 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
624 if (vm_start_gap(tmp) < gap + length - 1) {
625 low_limit = tmp->vm_end;
626 vma_iter_reset(&vmi);
627 goto retry;
628 }
629 } else {
630 tmp = vma_prev(&vmi);
631 if (tmp && vm_end_gap(tmp) > gap) {
632 low_limit = vm_end_gap(tmp);
633 vma_iter_reset(&vmi);
634 goto retry;
635 }
636 }
637
638 return gap;
639}
640
641/**
642 * unmapped_area_topdown() - Find an area between the low_limit and the
643 * high_limit with the correct alignment and offset at the highest available
644 * address, all from @info. Note: current->mm is used for the search.
645 *
646 * @info: The unmapped area information including the range [low_limit -
647 * high_limit), the alignment offset and mask.
648 *
649 * Return: A memory address or -ENOMEM.
650 */
651static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
652{
653 unsigned long length, gap, gap_end;
654 unsigned long low_limit, high_limit;
655 struct vm_area_struct *tmp;
656 VMA_ITERATOR(vmi, current->mm, 0);
657
658 /* Adjust search length to account for worst case alignment overhead */
659 length = info->length + info->align_mask + info->start_gap;
660 if (length < info->length)
661 return -ENOMEM;
662
663 low_limit = info->low_limit;
664 if (low_limit < mmap_min_addr)
665 low_limit = mmap_min_addr;
666 high_limit = info->high_limit;
667retry:
668 if (vma_iter_area_highest(&vmi, low_limit, high_limit, length))
669 return -ENOMEM;
670
671 gap = vma_iter_end(&vmi) - info->length;
672 gap -= (gap - info->align_offset) & info->align_mask;
673 gap_end = vma_iter_end(&vmi);
674 tmp = vma_next(&vmi);
675 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
676 if (vm_start_gap(tmp) < gap_end) {
677 high_limit = vm_start_gap(tmp);
678 vma_iter_reset(&vmi);
679 goto retry;
680 }
681 } else {
682 tmp = vma_prev(&vmi);
683 if (tmp && vm_end_gap(tmp) > gap) {
684 high_limit = tmp->vm_start;
685 vma_iter_reset(&vmi);
686 goto retry;
687 }
688 }
689
690 return gap;
691}
692
693/*
694 * Determine if the allocation needs to ensure that there is no
695 * existing mapping within it's guard gaps, for use as start_gap.
696 */
697static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
698{
699 if (vm_flags & VM_SHADOW_STACK)
700 return PAGE_SIZE;
701
702 return 0;
703}
704
705/*
706 * Search for an unmapped address range.
707 *
708 * We are looking for a range that:
709 * - does not intersect with any VMA;
710 * - is contained within the [low_limit, high_limit) interval;
711 * - is at least the desired size.
712 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
713 */
714unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
715{
716 unsigned long addr;
717
718 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
719 addr = unmapped_area_topdown(info);
720 else
721 addr = unmapped_area(info);
722
723 trace_vm_unmapped_area(addr, info);
724 return addr;
725}
726
727/* Get an address range which is currently unmapped.
728 * For shmat() with addr=0.
729 *
730 * Ugly calling convention alert:
731 * Return value with the low bits set means error value,
732 * ie
733 * if (ret & ~PAGE_MASK)
734 * error = ret;
735 *
736 * This function "knows" that -ENOMEM has the bits set.
737 */
738unsigned long
739generic_get_unmapped_area(struct file *filp, unsigned long addr,
740 unsigned long len, unsigned long pgoff,
741 unsigned long flags, vm_flags_t vm_flags)
742{
743 struct mm_struct *mm = current->mm;
744 struct vm_area_struct *vma, *prev;
745 struct vm_unmapped_area_info info = {};
746 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
747
748 if (len > mmap_end - mmap_min_addr)
749 return -ENOMEM;
750
751 if (flags & MAP_FIXED)
752 return addr;
753
754 if (addr) {
755 addr = PAGE_ALIGN(addr);
756 vma = find_vma_prev(mm, addr, &prev);
757 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
758 (!vma || addr + len <= vm_start_gap(vma)) &&
759 (!prev || addr >= vm_end_gap(prev)))
760 return addr;
761 }
762
763 info.length = len;
764 info.low_limit = mm->mmap_base;
765 info.high_limit = mmap_end;
766 info.start_gap = stack_guard_placement(vm_flags);
767 if (filp && is_file_hugepages(filp))
768 info.align_mask = huge_page_mask_align(filp);
769 return vm_unmapped_area(&info);
770}
771
772#ifndef HAVE_ARCH_UNMAPPED_AREA
773unsigned long
774arch_get_unmapped_area(struct file *filp, unsigned long addr,
775 unsigned long len, unsigned long pgoff,
776 unsigned long flags, vm_flags_t vm_flags)
777{
778 return generic_get_unmapped_area(filp, addr, len, pgoff, flags,
779 vm_flags);
780}
781#endif
782
783/*
784 * This mmap-allocator allocates new areas top-down from below the
785 * stack's low limit (the base):
786 */
787unsigned long
788generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
789 unsigned long len, unsigned long pgoff,
790 unsigned long flags, vm_flags_t vm_flags)
791{
792 struct vm_area_struct *vma, *prev;
793 struct mm_struct *mm = current->mm;
794 struct vm_unmapped_area_info info = {};
795 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
796
797 /* requested length too big for entire address space */
798 if (len > mmap_end - mmap_min_addr)
799 return -ENOMEM;
800
801 if (flags & MAP_FIXED)
802 return addr;
803
804 /* requesting a specific address */
805 if (addr) {
806 addr = PAGE_ALIGN(addr);
807 vma = find_vma_prev(mm, addr, &prev);
808 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
809 (!vma || addr + len <= vm_start_gap(vma)) &&
810 (!prev || addr >= vm_end_gap(prev)))
811 return addr;
812 }
813
814 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
815 info.length = len;
816 info.low_limit = PAGE_SIZE;
817 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
818 info.start_gap = stack_guard_placement(vm_flags);
819 if (filp && is_file_hugepages(filp))
820 info.align_mask = huge_page_mask_align(filp);
821 addr = vm_unmapped_area(&info);
822
823 /*
824 * A failed mmap() very likely causes application failure,
825 * so fall back to the bottom-up function here. This scenario
826 * can happen with large stack limits and large mmap()
827 * allocations.
828 */
829 if (offset_in_page(addr)) {
830 VM_BUG_ON(addr != -ENOMEM);
831 info.flags = 0;
832 info.low_limit = TASK_UNMAPPED_BASE;
833 info.high_limit = mmap_end;
834 addr = vm_unmapped_area(&info);
835 }
836
837 return addr;
838}
839
840#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
841unsigned long
842arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
843 unsigned long len, unsigned long pgoff,
844 unsigned long flags, vm_flags_t vm_flags)
845{
846 return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags,
847 vm_flags);
848}
849#endif
850
851unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *filp,
852 unsigned long addr, unsigned long len,
853 unsigned long pgoff, unsigned long flags,
854 vm_flags_t vm_flags)
855{
856 if (test_bit(MMF_TOPDOWN, &mm->flags))
857 return arch_get_unmapped_area_topdown(filp, addr, len, pgoff,
858 flags, vm_flags);
859 return arch_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags);
860}
861
862unsigned long
863__get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
864 unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags)
865{
866 unsigned long (*get_area)(struct file *, unsigned long,
867 unsigned long, unsigned long, unsigned long)
868 = NULL;
869
870 unsigned long error = arch_mmap_check(addr, len, flags);
871 if (error)
872 return error;
873
874 /* Careful about overflows.. */
875 if (len > TASK_SIZE)
876 return -ENOMEM;
877
878 if (file) {
879 if (file->f_op->get_unmapped_area)
880 get_area = file->f_op->get_unmapped_area;
881 } else if (flags & MAP_SHARED) {
882 /*
883 * mmap_region() will call shmem_zero_setup() to create a file,
884 * so use shmem's get_unmapped_area in case it can be huge.
885 */
886 get_area = shmem_get_unmapped_area;
887 }
888
889 /* Always treat pgoff as zero for anonymous memory. */
890 if (!file)
891 pgoff = 0;
892
893 if (get_area) {
894 addr = get_area(file, addr, len, pgoff, flags);
895 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && !file
896 && !addr /* no hint */
897 && IS_ALIGNED(len, PMD_SIZE)) {
898 /* Ensures that larger anonymous mappings are THP aligned. */
899 addr = thp_get_unmapped_area_vmflags(file, addr, len,
900 pgoff, flags, vm_flags);
901 } else {
902 addr = mm_get_unmapped_area_vmflags(current->mm, file, addr, len,
903 pgoff, flags, vm_flags);
904 }
905 if (IS_ERR_VALUE(addr))
906 return addr;
907
908 if (addr > TASK_SIZE - len)
909 return -ENOMEM;
910 if (offset_in_page(addr))
911 return -EINVAL;
912
913 error = security_mmap_addr(addr);
914 return error ? error : addr;
915}
916
917unsigned long
918mm_get_unmapped_area(struct mm_struct *mm, struct file *file,
919 unsigned long addr, unsigned long len,
920 unsigned long pgoff, unsigned long flags)
921{
922 if (test_bit(MMF_TOPDOWN, &mm->flags))
923 return arch_get_unmapped_area_topdown(file, addr, len, pgoff, flags, 0);
924 return arch_get_unmapped_area(file, addr, len, pgoff, flags, 0);
925}
926EXPORT_SYMBOL(mm_get_unmapped_area);
927
928/**
929 * find_vma_intersection() - Look up the first VMA which intersects the interval
930 * @mm: The process address space.
931 * @start_addr: The inclusive start user address.
932 * @end_addr: The exclusive end user address.
933 *
934 * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
935 * start_addr < end_addr.
936 */
937struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
938 unsigned long start_addr,
939 unsigned long end_addr)
940{
941 unsigned long index = start_addr;
942
943 mmap_assert_locked(mm);
944 return mt_find(&mm->mm_mt, &index, end_addr - 1);
945}
946EXPORT_SYMBOL(find_vma_intersection);
947
948/**
949 * find_vma() - Find the VMA for a given address, or the next VMA.
950 * @mm: The mm_struct to check
951 * @addr: The address
952 *
953 * Returns: The VMA associated with addr, or the next VMA.
954 * May return %NULL in the case of no VMA at addr or above.
955 */
956struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
957{
958 unsigned long index = addr;
959
960 mmap_assert_locked(mm);
961 return mt_find(&mm->mm_mt, &index, ULONG_MAX);
962}
963EXPORT_SYMBOL(find_vma);
964
965/**
966 * find_vma_prev() - Find the VMA for a given address, or the next vma and
967 * set %pprev to the previous VMA, if any.
968 * @mm: The mm_struct to check
969 * @addr: The address
970 * @pprev: The pointer to set to the previous VMA
971 *
972 * Note that RCU lock is missing here since the external mmap_lock() is used
973 * instead.
974 *
975 * Returns: The VMA associated with @addr, or the next vma.
976 * May return %NULL in the case of no vma at addr or above.
977 */
978struct vm_area_struct *
979find_vma_prev(struct mm_struct *mm, unsigned long addr,
980 struct vm_area_struct **pprev)
981{
982 struct vm_area_struct *vma;
983 VMA_ITERATOR(vmi, mm, addr);
984
985 vma = vma_iter_load(&vmi);
986 *pprev = vma_prev(&vmi);
987 if (!vma)
988 vma = vma_next(&vmi);
989 return vma;
990}
991
992/*
993 * Verify that the stack growth is acceptable and
994 * update accounting. This is shared with both the
995 * grow-up and grow-down cases.
996 */
997static int acct_stack_growth(struct vm_area_struct *vma,
998 unsigned long size, unsigned long grow)
999{
1000 struct mm_struct *mm = vma->vm_mm;
1001 unsigned long new_start;
1002
1003 /* address space limit tests */
1004 if (!may_expand_vm(mm, vma->vm_flags, grow))
1005 return -ENOMEM;
1006
1007 /* Stack limit test */
1008 if (size > rlimit(RLIMIT_STACK))
1009 return -ENOMEM;
1010
1011 /* mlock limit tests */
1012 if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
1013 return -ENOMEM;
1014
1015 /* Check to ensure the stack will not grow into a hugetlb-only region */
1016 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1017 vma->vm_end - size;
1018 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1019 return -EFAULT;
1020
1021 /*
1022 * Overcommit.. This must be the final test, as it will
1023 * update security statistics.
1024 */
1025 if (security_vm_enough_memory_mm(mm, grow))
1026 return -ENOMEM;
1027
1028 return 0;
1029}
1030
1031#if defined(CONFIG_STACK_GROWSUP)
1032/*
1033 * PA-RISC uses this for its stack.
1034 * vma is the last one with address > vma->vm_end. Have to extend vma.
1035 */
1036static int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1037{
1038 struct mm_struct *mm = vma->vm_mm;
1039 struct vm_area_struct *next;
1040 unsigned long gap_addr;
1041 int error = 0;
1042 VMA_ITERATOR(vmi, mm, vma->vm_start);
1043
1044 if (!(vma->vm_flags & VM_GROWSUP))
1045 return -EFAULT;
1046
1047 mmap_assert_write_locked(mm);
1048
1049 /* Guard against exceeding limits of the address space. */
1050 address &= PAGE_MASK;
1051 if (address >= (TASK_SIZE & PAGE_MASK))
1052 return -ENOMEM;
1053 address += PAGE_SIZE;
1054
1055 /* Enforce stack_guard_gap */
1056 gap_addr = address + stack_guard_gap;
1057
1058 /* Guard against overflow */
1059 if (gap_addr < address || gap_addr > TASK_SIZE)
1060 gap_addr = TASK_SIZE;
1061
1062 next = find_vma_intersection(mm, vma->vm_end, gap_addr);
1063 if (next && vma_is_accessible(next)) {
1064 if (!(next->vm_flags & VM_GROWSUP))
1065 return -ENOMEM;
1066 /* Check that both stack segments have the same anon_vma? */
1067 }
1068
1069 if (next)
1070 vma_iter_prev_range_limit(&vmi, address);
1071
1072 vma_iter_config(&vmi, vma->vm_start, address);
1073 if (vma_iter_prealloc(&vmi, vma))
1074 return -ENOMEM;
1075
1076 /* We must make sure the anon_vma is allocated. */
1077 if (unlikely(anon_vma_prepare(vma))) {
1078 vma_iter_free(&vmi);
1079 return -ENOMEM;
1080 }
1081
1082 /* Lock the VMA before expanding to prevent concurrent page faults */
1083 vma_start_write(vma);
1084 /* We update the anon VMA tree. */
1085 anon_vma_lock_write(vma->anon_vma);
1086
1087 /* Somebody else might have raced and expanded it already */
1088 if (address > vma->vm_end) {
1089 unsigned long size, grow;
1090
1091 size = address - vma->vm_start;
1092 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1093
1094 error = -ENOMEM;
1095 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1096 error = acct_stack_growth(vma, size, grow);
1097 if (!error) {
1098 if (vma->vm_flags & VM_LOCKED)
1099 mm->locked_vm += grow;
1100 vm_stat_account(mm, vma->vm_flags, grow);
1101 anon_vma_interval_tree_pre_update_vma(vma);
1102 vma->vm_end = address;
1103 /* Overwrite old entry in mtree. */
1104 vma_iter_store(&vmi, vma);
1105 anon_vma_interval_tree_post_update_vma(vma);
1106
1107 perf_event_mmap(vma);
1108 }
1109 }
1110 }
1111 anon_vma_unlock_write(vma->anon_vma);
1112 vma_iter_free(&vmi);
1113 validate_mm(mm);
1114 return error;
1115}
1116#endif /* CONFIG_STACK_GROWSUP */
1117
1118/*
1119 * vma is the first one with address < vma->vm_start. Have to extend vma.
1120 * mmap_lock held for writing.
1121 */
1122int expand_downwards(struct vm_area_struct *vma, unsigned long address)
1123{
1124 struct mm_struct *mm = vma->vm_mm;
1125 struct vm_area_struct *prev;
1126 int error = 0;
1127 VMA_ITERATOR(vmi, mm, vma->vm_start);
1128
1129 if (!(vma->vm_flags & VM_GROWSDOWN))
1130 return -EFAULT;
1131
1132 mmap_assert_write_locked(mm);
1133
1134 address &= PAGE_MASK;
1135 if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)
1136 return -EPERM;
1137
1138 /* Enforce stack_guard_gap */
1139 prev = vma_prev(&vmi);
1140 /* Check that both stack segments have the same anon_vma? */
1141 if (prev) {
1142 if (!(prev->vm_flags & VM_GROWSDOWN) &&
1143 vma_is_accessible(prev) &&
1144 (address - prev->vm_end < stack_guard_gap))
1145 return -ENOMEM;
1146 }
1147
1148 if (prev)
1149 vma_iter_next_range_limit(&vmi, vma->vm_start);
1150
1151 vma_iter_config(&vmi, address, vma->vm_end);
1152 if (vma_iter_prealloc(&vmi, vma))
1153 return -ENOMEM;
1154
1155 /* We must make sure the anon_vma is allocated. */
1156 if (unlikely(anon_vma_prepare(vma))) {
1157 vma_iter_free(&vmi);
1158 return -ENOMEM;
1159 }
1160
1161 /* Lock the VMA before expanding to prevent concurrent page faults */
1162 vma_start_write(vma);
1163 /* We update the anon VMA tree. */
1164 anon_vma_lock_write(vma->anon_vma);
1165
1166 /* Somebody else might have raced and expanded it already */
1167 if (address < vma->vm_start) {
1168 unsigned long size, grow;
1169
1170 size = vma->vm_end - address;
1171 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1172
1173 error = -ENOMEM;
1174 if (grow <= vma->vm_pgoff) {
1175 error = acct_stack_growth(vma, size, grow);
1176 if (!error) {
1177 if (vma->vm_flags & VM_LOCKED)
1178 mm->locked_vm += grow;
1179 vm_stat_account(mm, vma->vm_flags, grow);
1180 anon_vma_interval_tree_pre_update_vma(vma);
1181 vma->vm_start = address;
1182 vma->vm_pgoff -= grow;
1183 /* Overwrite old entry in mtree. */
1184 vma_iter_store(&vmi, vma);
1185 anon_vma_interval_tree_post_update_vma(vma);
1186
1187 perf_event_mmap(vma);
1188 }
1189 }
1190 }
1191 anon_vma_unlock_write(vma->anon_vma);
1192 vma_iter_free(&vmi);
1193 validate_mm(mm);
1194 return error;
1195}
1196
1197/* enforced gap between the expanding stack and other mappings. */
1198unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
1199
1200static int __init cmdline_parse_stack_guard_gap(char *p)
1201{
1202 unsigned long val;
1203 char *endptr;
1204
1205 val = simple_strtoul(p, &endptr, 10);
1206 if (!*endptr)
1207 stack_guard_gap = val << PAGE_SHIFT;
1208
1209 return 1;
1210}
1211__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
1212
1213#ifdef CONFIG_STACK_GROWSUP
1214int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
1215{
1216 return expand_upwards(vma, address);
1217}
1218
1219struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
1220{
1221 struct vm_area_struct *vma, *prev;
1222
1223 addr &= PAGE_MASK;
1224 vma = find_vma_prev(mm, addr, &prev);
1225 if (vma && (vma->vm_start <= addr))
1226 return vma;
1227 if (!prev)
1228 return NULL;
1229 if (expand_stack_locked(prev, addr))
1230 return NULL;
1231 if (prev->vm_flags & VM_LOCKED)
1232 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
1233 return prev;
1234}
1235#else
1236int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
1237{
1238 return expand_downwards(vma, address);
1239}
1240
1241struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
1242{
1243 struct vm_area_struct *vma;
1244 unsigned long start;
1245
1246 addr &= PAGE_MASK;
1247 vma = find_vma(mm, addr);
1248 if (!vma)
1249 return NULL;
1250 if (vma->vm_start <= addr)
1251 return vma;
1252 start = vma->vm_start;
1253 if (expand_stack_locked(vma, addr))
1254 return NULL;
1255 if (vma->vm_flags & VM_LOCKED)
1256 populate_vma_page_range(vma, addr, start, NULL);
1257 return vma;
1258}
1259#endif
1260
1261#if defined(CONFIG_STACK_GROWSUP)
1262
1263#define vma_expand_up(vma,addr) expand_upwards(vma, addr)
1264#define vma_expand_down(vma, addr) (-EFAULT)
1265
1266#else
1267
1268#define vma_expand_up(vma,addr) (-EFAULT)
1269#define vma_expand_down(vma, addr) expand_downwards(vma, addr)
1270
1271#endif
1272
1273/*
1274 * expand_stack(): legacy interface for page faulting. Don't use unless
1275 * you have to.
1276 *
1277 * This is called with the mm locked for reading, drops the lock, takes
1278 * the lock for writing, tries to look up a vma again, expands it if
1279 * necessary, and downgrades the lock to reading again.
1280 *
1281 * If no vma is found or it can't be expanded, it returns NULL and has
1282 * dropped the lock.
1283 */
1284struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
1285{
1286 struct vm_area_struct *vma, *prev;
1287
1288 mmap_read_unlock(mm);
1289 if (mmap_write_lock_killable(mm))
1290 return NULL;
1291
1292 vma = find_vma_prev(mm, addr, &prev);
1293 if (vma && vma->vm_start <= addr)
1294 goto success;
1295
1296 if (prev && !vma_expand_up(prev, addr)) {
1297 vma = prev;
1298 goto success;
1299 }
1300
1301 if (vma && !vma_expand_down(vma, addr))
1302 goto success;
1303
1304 mmap_write_unlock(mm);
1305 return NULL;
1306
1307success:
1308 mmap_write_downgrade(mm);
1309 return vma;
1310}
1311
1312/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
1313 * @mm: The mm_struct
1314 * @start: The start address to munmap
1315 * @len: The length to be munmapped.
1316 * @uf: The userfaultfd list_head
1317 *
1318 * Return: 0 on success, error otherwise.
1319 */
1320int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
1321 struct list_head *uf)
1322{
1323 VMA_ITERATOR(vmi, mm, start);
1324
1325 return do_vmi_munmap(&vmi, mm, start, len, uf, false);
1326}
1327
1328unsigned long mmap_region(struct file *file, unsigned long addr,
1329 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1330 struct list_head *uf)
1331{
1332 unsigned long ret;
1333 bool writable_file_mapping = false;
1334
1335 /* Check to see if MDWE is applicable. */
1336 if (map_deny_write_exec(vm_flags, vm_flags))
1337 return -EACCES;
1338
1339 /* Allow architectures to sanity-check the vm_flags. */
1340 if (!arch_validate_flags(vm_flags))
1341 return -EINVAL;
1342
1343 /* Map writable and ensure this isn't a sealed memfd. */
1344 if (file && is_shared_maywrite(vm_flags)) {
1345 int error = mapping_map_writable(file->f_mapping);
1346
1347 if (error)
1348 return error;
1349 writable_file_mapping = true;
1350 }
1351
1352 ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf);
1353
1354 /* Clear our write mapping regardless of error. */
1355 if (writable_file_mapping)
1356 mapping_unmap_writable(file->f_mapping);
1357
1358 validate_mm(current->mm);
1359 return ret;
1360}
1361
1362static int __vm_munmap(unsigned long start, size_t len, bool unlock)
1363{
1364 int ret;
1365 struct mm_struct *mm = current->mm;
1366 LIST_HEAD(uf);
1367 VMA_ITERATOR(vmi, mm, start);
1368
1369 if (mmap_write_lock_killable(mm))
1370 return -EINTR;
1371
1372 ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock);
1373 if (ret || !unlock)
1374 mmap_write_unlock(mm);
1375
1376 userfaultfd_unmap_complete(mm, &uf);
1377 return ret;
1378}
1379
1380int vm_munmap(unsigned long start, size_t len)
1381{
1382 return __vm_munmap(start, len, false);
1383}
1384EXPORT_SYMBOL(vm_munmap);
1385
1386SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1387{
1388 addr = untagged_addr(addr);
1389 return __vm_munmap(addr, len, true);
1390}
1391
1392
1393/*
1394 * Emulation of deprecated remap_file_pages() syscall.
1395 */
1396SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
1397 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
1398{
1399
1400 struct mm_struct *mm = current->mm;
1401 struct vm_area_struct *vma;
1402 unsigned long populate = 0;
1403 unsigned long ret = -EINVAL;
1404 struct file *file;
1405 vm_flags_t vm_flags;
1406
1407 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
1408 current->comm, current->pid);
1409
1410 if (prot)
1411 return ret;
1412 start = start & PAGE_MASK;
1413 size = size & PAGE_MASK;
1414
1415 if (start + size <= start)
1416 return ret;
1417
1418 /* Does pgoff wrap? */
1419 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
1420 return ret;
1421
1422 if (mmap_read_lock_killable(mm))
1423 return -EINTR;
1424
1425 /*
1426 * Look up VMA under read lock first so we can perform the security
1427 * without holding locks (which can be problematic). We reacquire a
1428 * write lock later and check nothing changed underneath us.
1429 */
1430 vma = vma_lookup(mm, start);
1431
1432 if (!vma || !(vma->vm_flags & VM_SHARED)) {
1433 mmap_read_unlock(mm);
1434 return -EINVAL;
1435 }
1436
1437 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
1438 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
1439 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
1440
1441 flags &= MAP_NONBLOCK;
1442 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
1443 if (vma->vm_flags & VM_LOCKED)
1444 flags |= MAP_LOCKED;
1445
1446 /* Save vm_flags used to calculate prot and flags, and recheck later. */
1447 vm_flags = vma->vm_flags;
1448 file = get_file(vma->vm_file);
1449
1450 mmap_read_unlock(mm);
1451
1452 /* Call outside mmap_lock to be consistent with other callers. */
1453 ret = security_mmap_file(file, prot, flags);
1454 if (ret) {
1455 fput(file);
1456 return ret;
1457 }
1458
1459 ret = -EINVAL;
1460
1461 /* OK security check passed, take write lock + let it rip. */
1462 if (mmap_write_lock_killable(mm)) {
1463 fput(file);
1464 return -EINTR;
1465 }
1466
1467 vma = vma_lookup(mm, start);
1468
1469 if (!vma)
1470 goto out;
1471
1472 /* Make sure things didn't change under us. */
1473 if (vma->vm_flags != vm_flags)
1474 goto out;
1475 if (vma->vm_file != file)
1476 goto out;
1477
1478 if (start + size > vma->vm_end) {
1479 VMA_ITERATOR(vmi, mm, vma->vm_end);
1480 struct vm_area_struct *next, *prev = vma;
1481
1482 for_each_vma_range(vmi, next, start + size) {
1483 /* hole between vmas ? */
1484 if (next->vm_start != prev->vm_end)
1485 goto out;
1486
1487 if (next->vm_file != vma->vm_file)
1488 goto out;
1489
1490 if (next->vm_flags != vma->vm_flags)
1491 goto out;
1492
1493 if (start + size <= next->vm_end)
1494 break;
1495
1496 prev = next;
1497 }
1498
1499 if (!next)
1500 goto out;
1501 }
1502
1503 ret = do_mmap(vma->vm_file, start, size,
1504 prot, flags, 0, pgoff, &populate, NULL);
1505out:
1506 mmap_write_unlock(mm);
1507 fput(file);
1508 if (populate)
1509 mm_populate(ret, populate);
1510 if (!IS_ERR_VALUE(ret))
1511 ret = 0;
1512 return ret;
1513}
1514
1515/*
1516 * do_brk_flags() - Increase the brk vma if the flags match.
1517 * @vmi: The vma iterator
1518 * @addr: The start address
1519 * @len: The length of the increase
1520 * @vma: The vma,
1521 * @flags: The VMA Flags
1522 *
1523 * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags
1524 * do not match then create a new anonymous VMA. Eventually we may be able to
1525 * do some brk-specific accounting here.
1526 */
1527static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
1528 unsigned long addr, unsigned long len, unsigned long flags)
1529{
1530 struct mm_struct *mm = current->mm;
1531
1532 /*
1533 * Check against address space limits by the changed size
1534 * Note: This happens *after* clearing old mappings in some code paths.
1535 */
1536 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1537 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
1538 return -ENOMEM;
1539
1540 if (mm->map_count > sysctl_max_map_count)
1541 return -ENOMEM;
1542
1543 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
1544 return -ENOMEM;
1545
1546 /*
1547 * Expand the existing vma if possible; Note that singular lists do not
1548 * occur after forking, so the expand will only happen on new VMAs.
1549 */
1550 if (vma && vma->vm_end == addr) {
1551 VMG_STATE(vmg, mm, vmi, addr, addr + len, flags, PHYS_PFN(addr));
1552
1553 vmg.prev = vma;
1554 /* vmi is positioned at prev, which this mode expects. */
1555 vmg.merge_flags = VMG_FLAG_JUST_EXPAND;
1556
1557 if (vma_merge_new_range(&vmg))
1558 goto out;
1559 else if (vmg_nomem(&vmg))
1560 goto unacct_fail;
1561 }
1562
1563 if (vma)
1564 vma_iter_next_range(vmi);
1565 /* create a vma struct for an anonymous mapping */
1566 vma = vm_area_alloc(mm);
1567 if (!vma)
1568 goto unacct_fail;
1569
1570 vma_set_anonymous(vma);
1571 vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT);
1572 vm_flags_init(vma, flags);
1573 vma->vm_page_prot = vm_get_page_prot(flags);
1574 vma_start_write(vma);
1575 if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
1576 goto mas_store_fail;
1577
1578 mm->map_count++;
1579 validate_mm(mm);
1580 ksm_add_vma(vma);
1581out:
1582 perf_event_mmap(vma);
1583 mm->total_vm += len >> PAGE_SHIFT;
1584 mm->data_vm += len >> PAGE_SHIFT;
1585 if (flags & VM_LOCKED)
1586 mm->locked_vm += (len >> PAGE_SHIFT);
1587 vm_flags_set(vma, VM_SOFTDIRTY);
1588 return 0;
1589
1590mas_store_fail:
1591 vm_area_free(vma);
1592unacct_fail:
1593 vm_unacct_memory(len >> PAGE_SHIFT);
1594 return -ENOMEM;
1595}
1596
1597int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
1598{
1599 struct mm_struct *mm = current->mm;
1600 struct vm_area_struct *vma = NULL;
1601 unsigned long len;
1602 int ret;
1603 bool populate;
1604 LIST_HEAD(uf);
1605 VMA_ITERATOR(vmi, mm, addr);
1606
1607 len = PAGE_ALIGN(request);
1608 if (len < request)
1609 return -ENOMEM;
1610 if (!len)
1611 return 0;
1612
1613 /* Until we need other flags, refuse anything except VM_EXEC. */
1614 if ((flags & (~VM_EXEC)) != 0)
1615 return -EINVAL;
1616
1617 if (mmap_write_lock_killable(mm))
1618 return -EINTR;
1619
1620 ret = check_brk_limits(addr, len);
1621 if (ret)
1622 goto limits_failed;
1623
1624 ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0);
1625 if (ret)
1626 goto munmap_failed;
1627
1628 vma = vma_prev(&vmi);
1629 ret = do_brk_flags(&vmi, vma, addr, len, flags);
1630 populate = ((mm->def_flags & VM_LOCKED) != 0);
1631 mmap_write_unlock(mm);
1632 userfaultfd_unmap_complete(mm, &uf);
1633 if (populate && !ret)
1634 mm_populate(addr, len);
1635 return ret;
1636
1637munmap_failed:
1638limits_failed:
1639 mmap_write_unlock(mm);
1640 return ret;
1641}
1642EXPORT_SYMBOL(vm_brk_flags);
1643
1644/* Release all mmaps. */
1645void exit_mmap(struct mm_struct *mm)
1646{
1647 struct mmu_gather tlb;
1648 struct vm_area_struct *vma;
1649 unsigned long nr_accounted = 0;
1650 VMA_ITERATOR(vmi, mm, 0);
1651 int count = 0;
1652
1653 /* mm's last user has gone, and its about to be pulled down */
1654 mmu_notifier_release(mm);
1655
1656 mmap_read_lock(mm);
1657 arch_exit_mmap(mm);
1658
1659 vma = vma_next(&vmi);
1660 if (!vma || unlikely(xa_is_zero(vma))) {
1661 /* Can happen if dup_mmap() received an OOM */
1662 mmap_read_unlock(mm);
1663 mmap_write_lock(mm);
1664 goto destroy;
1665 }
1666
1667 lru_add_drain();
1668 flush_cache_mm(mm);
1669 tlb_gather_mmu_fullmm(&tlb, mm);
1670 /* update_hiwater_rss(mm) here? but nobody should be looking */
1671 /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
1672 unmap_vmas(&tlb, &vmi.mas, vma, 0, ULONG_MAX, ULONG_MAX, false);
1673 mmap_read_unlock(mm);
1674
1675 /*
1676 * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
1677 * because the memory has been already freed.
1678 */
1679 set_bit(MMF_OOM_SKIP, &mm->flags);
1680 mmap_write_lock(mm);
1681 mt_clear_in_rcu(&mm->mm_mt);
1682 vma_iter_set(&vmi, vma->vm_end);
1683 free_pgtables(&tlb, &vmi.mas, vma, FIRST_USER_ADDRESS,
1684 USER_PGTABLES_CEILING, true);
1685 tlb_finish_mmu(&tlb);
1686
1687 /*
1688 * Walk the list again, actually closing and freeing it, with preemption
1689 * enabled, without holding any MM locks besides the unreachable
1690 * mmap_write_lock.
1691 */
1692 vma_iter_set(&vmi, vma->vm_end);
1693 do {
1694 if (vma->vm_flags & VM_ACCOUNT)
1695 nr_accounted += vma_pages(vma);
1696 remove_vma(vma, /* unreachable = */ true);
1697 count++;
1698 cond_resched();
1699 vma = vma_next(&vmi);
1700 } while (vma && likely(!xa_is_zero(vma)));
1701
1702 BUG_ON(count != mm->map_count);
1703
1704 trace_exit_mmap(mm);
1705destroy:
1706 __mt_destroy(&mm->mm_mt);
1707 mmap_write_unlock(mm);
1708 vm_unacct_memory(nr_accounted);
1709}
1710
1711/* Insert vm structure into process list sorted by address
1712 * and into the inode's i_mmap tree. If vm_file is non-NULL
1713 * then i_mmap_rwsem is taken here.
1714 */
1715int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
1716{
1717 unsigned long charged = vma_pages(vma);
1718
1719
1720 if (find_vma_intersection(mm, vma->vm_start, vma->vm_end))
1721 return -ENOMEM;
1722
1723 if ((vma->vm_flags & VM_ACCOUNT) &&
1724 security_vm_enough_memory_mm(mm, charged))
1725 return -ENOMEM;
1726
1727 /*
1728 * The vm_pgoff of a purely anonymous vma should be irrelevant
1729 * until its first write fault, when page's anon_vma and index
1730 * are set. But now set the vm_pgoff it will almost certainly
1731 * end up with (unless mremap moves it elsewhere before that
1732 * first wfault), so /proc/pid/maps tells a consistent story.
1733 *
1734 * By setting it to reflect the virtual start address of the
1735 * vma, merges and splits can happen in a seamless way, just
1736 * using the existing file pgoff checks and manipulations.
1737 * Similarly in do_mmap and in do_brk_flags.
1738 */
1739 if (vma_is_anonymous(vma)) {
1740 BUG_ON(vma->anon_vma);
1741 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
1742 }
1743
1744 if (vma_link(mm, vma)) {
1745 if (vma->vm_flags & VM_ACCOUNT)
1746 vm_unacct_memory(charged);
1747 return -ENOMEM;
1748 }
1749
1750 return 0;
1751}
1752
1753/*
1754 * Return true if the calling process may expand its vm space by the passed
1755 * number of pages
1756 */
1757bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
1758{
1759 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
1760 return false;
1761
1762 if (is_data_mapping(flags) &&
1763 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
1764 /* Workaround for Valgrind */
1765 if (rlimit(RLIMIT_DATA) == 0 &&
1766 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
1767 return true;
1768
1769 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
1770 current->comm, current->pid,
1771 (mm->data_vm + npages) << PAGE_SHIFT,
1772 rlimit(RLIMIT_DATA),
1773 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
1774
1775 if (!ignore_rlimit_data)
1776 return false;
1777 }
1778
1779 return true;
1780}
1781
1782void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
1783{
1784 WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages);
1785
1786 if (is_exec_mapping(flags))
1787 mm->exec_vm += npages;
1788 else if (is_stack_mapping(flags))
1789 mm->stack_vm += npages;
1790 else if (is_data_mapping(flags))
1791 mm->data_vm += npages;
1792}
1793
1794static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
1795
1796/*
1797 * Close hook, called for unmap() and on the old vma for mremap().
1798 *
1799 * Having a close hook prevents vma merging regardless of flags.
1800 */
1801static void special_mapping_close(struct vm_area_struct *vma)
1802{
1803 const struct vm_special_mapping *sm = vma->vm_private_data;
1804
1805 if (sm->close)
1806 sm->close(sm, vma);
1807}
1808
1809static const char *special_mapping_name(struct vm_area_struct *vma)
1810{
1811 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
1812}
1813
1814static int special_mapping_mremap(struct vm_area_struct *new_vma)
1815{
1816 struct vm_special_mapping *sm = new_vma->vm_private_data;
1817
1818 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
1819 return -EFAULT;
1820
1821 if (sm->mremap)
1822 return sm->mremap(sm, new_vma);
1823
1824 return 0;
1825}
1826
1827static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
1828{
1829 /*
1830 * Forbid splitting special mappings - kernel has expectations over
1831 * the number of pages in mapping. Together with VM_DONTEXPAND
1832 * the size of vma should stay the same over the special mapping's
1833 * lifetime.
1834 */
1835 return -EINVAL;
1836}
1837
1838static const struct vm_operations_struct special_mapping_vmops = {
1839 .close = special_mapping_close,
1840 .fault = special_mapping_fault,
1841 .mremap = special_mapping_mremap,
1842 .name = special_mapping_name,
1843 /* vDSO code relies that VVAR can't be accessed remotely */
1844 .access = NULL,
1845 .may_split = special_mapping_split,
1846};
1847
1848static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
1849{
1850 struct vm_area_struct *vma = vmf->vma;
1851 pgoff_t pgoff;
1852 struct page **pages;
1853 struct vm_special_mapping *sm = vma->vm_private_data;
1854
1855 if (sm->fault)
1856 return sm->fault(sm, vmf->vma, vmf);
1857
1858 pages = sm->pages;
1859
1860 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
1861 pgoff--;
1862
1863 if (*pages) {
1864 struct page *page = *pages;
1865 get_page(page);
1866 vmf->page = page;
1867 return 0;
1868 }
1869
1870 return VM_FAULT_SIGBUS;
1871}
1872
1873static struct vm_area_struct *__install_special_mapping(
1874 struct mm_struct *mm,
1875 unsigned long addr, unsigned long len,
1876 unsigned long vm_flags, void *priv,
1877 const struct vm_operations_struct *ops)
1878{
1879 int ret;
1880 struct vm_area_struct *vma;
1881
1882 vma = vm_area_alloc(mm);
1883 if (unlikely(vma == NULL))
1884 return ERR_PTR(-ENOMEM);
1885
1886 vma_set_range(vma, addr, addr + len, 0);
1887 vm_flags_init(vma, (vm_flags | mm->def_flags |
1888 VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
1889 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
1890
1891 vma->vm_ops = ops;
1892 vma->vm_private_data = priv;
1893
1894 ret = insert_vm_struct(mm, vma);
1895 if (ret)
1896 goto out;
1897
1898 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
1899
1900 perf_event_mmap(vma);
1901
1902 return vma;
1903
1904out:
1905 vm_area_free(vma);
1906 return ERR_PTR(ret);
1907}
1908
1909bool vma_is_special_mapping(const struct vm_area_struct *vma,
1910 const struct vm_special_mapping *sm)
1911{
1912 return vma->vm_private_data == sm &&
1913 vma->vm_ops == &special_mapping_vmops;
1914}
1915
1916/*
1917 * Called with mm->mmap_lock held for writing.
1918 * Insert a new vma covering the given region, with the given flags.
1919 * Its pages are supplied by the given array of struct page *.
1920 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
1921 * The region past the last page supplied will always produce SIGBUS.
1922 * The array pointer and the pages it points to are assumed to stay alive
1923 * for as long as this mapping might exist.
1924 */
1925struct vm_area_struct *_install_special_mapping(
1926 struct mm_struct *mm,
1927 unsigned long addr, unsigned long len,
1928 unsigned long vm_flags, const struct vm_special_mapping *spec)
1929{
1930 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
1931 &special_mapping_vmops);
1932}
1933
1934/*
1935 * initialise the percpu counter for VM
1936 */
1937void __init mmap_init(void)
1938{
1939 int ret;
1940
1941 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
1942 VM_BUG_ON(ret);
1943}
1944
1945/*
1946 * Initialise sysctl_user_reserve_kbytes.
1947 *
1948 * This is intended to prevent a user from starting a single memory hogging
1949 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1950 * mode.
1951 *
1952 * The default value is min(3% of free memory, 128MB)
1953 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1954 */
1955static int init_user_reserve(void)
1956{
1957 unsigned long free_kbytes;
1958
1959 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1960
1961 sysctl_user_reserve_kbytes = min(free_kbytes / 32, SZ_128K);
1962 return 0;
1963}
1964subsys_initcall(init_user_reserve);
1965
1966/*
1967 * Initialise sysctl_admin_reserve_kbytes.
1968 *
1969 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1970 * to log in and kill a memory hogging process.
1971 *
1972 * Systems with more than 256MB will reserve 8MB, enough to recover
1973 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1974 * only reserve 3% of free pages by default.
1975 */
1976static int init_admin_reserve(void)
1977{
1978 unsigned long free_kbytes;
1979
1980 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
1981
1982 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, SZ_8K);
1983 return 0;
1984}
1985subsys_initcall(init_admin_reserve);
1986
1987/*
1988 * Reinititalise user and admin reserves if memory is added or removed.
1989 *
1990 * The default user reserve max is 128MB, and the default max for the
1991 * admin reserve is 8MB. These are usually, but not always, enough to
1992 * enable recovery from a memory hogging process using login/sshd, a shell,
1993 * and tools like top. It may make sense to increase or even disable the
1994 * reserve depending on the existence of swap or variations in the recovery
1995 * tools. So, the admin may have changed them.
1996 *
1997 * If memory is added and the reserves have been eliminated or increased above
1998 * the default max, then we'll trust the admin.
1999 *
2000 * If memory is removed and there isn't enough free memory, then we
2001 * need to reset the reserves.
2002 *
2003 * Otherwise keep the reserve set by the admin.
2004 */
2005static int reserve_mem_notifier(struct notifier_block *nb,
2006 unsigned long action, void *data)
2007{
2008 unsigned long tmp, free_kbytes;
2009
2010 switch (action) {
2011 case MEM_ONLINE:
2012 /* Default max is 128MB. Leave alone if modified by operator. */
2013 tmp = sysctl_user_reserve_kbytes;
2014 if (tmp > 0 && tmp < SZ_128K)
2015 init_user_reserve();
2016
2017 /* Default max is 8MB. Leave alone if modified by operator. */
2018 tmp = sysctl_admin_reserve_kbytes;
2019 if (tmp > 0 && tmp < SZ_8K)
2020 init_admin_reserve();
2021
2022 break;
2023 case MEM_OFFLINE:
2024 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
2025
2026 if (sysctl_user_reserve_kbytes > free_kbytes) {
2027 init_user_reserve();
2028 pr_info("vm.user_reserve_kbytes reset to %lu\n",
2029 sysctl_user_reserve_kbytes);
2030 }
2031
2032 if (sysctl_admin_reserve_kbytes > free_kbytes) {
2033 init_admin_reserve();
2034 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
2035 sysctl_admin_reserve_kbytes);
2036 }
2037 break;
2038 default:
2039 break;
2040 }
2041 return NOTIFY_OK;
2042}
2043
2044static int __meminit init_reserve_notifier(void)
2045{
2046 if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
2047 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
2048
2049 return 0;
2050}
2051subsys_initcall(init_reserve_notifier);
2052
2053/*
2054 * Relocate a VMA downwards by shift bytes. There cannot be any VMAs between
2055 * this VMA and its relocated range, which will now reside at [vma->vm_start -
2056 * shift, vma->vm_end - shift).
2057 *
2058 * This function is almost certainly NOT what you want for anything other than
2059 * early executable temporary stack relocation.
2060 */
2061int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
2062{
2063 /*
2064 * The process proceeds as follows:
2065 *
2066 * 1) Use shift to calculate the new vma endpoints.
2067 * 2) Extend vma to cover both the old and new ranges. This ensures the
2068 * arguments passed to subsequent functions are consistent.
2069 * 3) Move vma's page tables to the new range.
2070 * 4) Free up any cleared pgd range.
2071 * 5) Shrink the vma to cover only the new range.
2072 */
2073
2074 struct mm_struct *mm = vma->vm_mm;
2075 unsigned long old_start = vma->vm_start;
2076 unsigned long old_end = vma->vm_end;
2077 unsigned long length = old_end - old_start;
2078 unsigned long new_start = old_start - shift;
2079 unsigned long new_end = old_end - shift;
2080 VMA_ITERATOR(vmi, mm, new_start);
2081 VMG_STATE(vmg, mm, &vmi, new_start, old_end, 0, vma->vm_pgoff);
2082 struct vm_area_struct *next;
2083 struct mmu_gather tlb;
2084
2085 BUG_ON(new_start > new_end);
2086
2087 /*
2088 * ensure there are no vmas between where we want to go
2089 * and where we are
2090 */
2091 if (vma != vma_next(&vmi))
2092 return -EFAULT;
2093
2094 vma_iter_prev_range(&vmi);
2095 /*
2096 * cover the whole range: [new_start, old_end)
2097 */
2098 vmg.vma = vma;
2099 if (vma_expand(&vmg))
2100 return -ENOMEM;
2101
2102 /*
2103 * move the page tables downwards, on failure we rely on
2104 * process cleanup to remove whatever mess we made.
2105 */
2106 if (length != move_page_tables(vma, old_start,
2107 vma, new_start, length, false, true))
2108 return -ENOMEM;
2109
2110 lru_add_drain();
2111 tlb_gather_mmu(&tlb, mm);
2112 next = vma_next(&vmi);
2113 if (new_end > old_start) {
2114 /*
2115 * when the old and new regions overlap clear from new_end.
2116 */
2117 free_pgd_range(&tlb, new_end, old_end, new_end,
2118 next ? next->vm_start : USER_PGTABLES_CEILING);
2119 } else {
2120 /*
2121 * otherwise, clean from old_start; this is done to not touch
2122 * the address space in [new_end, old_start) some architectures
2123 * have constraints on va-space that make this illegal (IA64) -
2124 * for the others its just a little faster.
2125 */
2126 free_pgd_range(&tlb, old_start, old_end, new_end,
2127 next ? next->vm_start : USER_PGTABLES_CEILING);
2128 }
2129 tlb_finish_mmu(&tlb);
2130
2131 vma_prev(&vmi);
2132 /* Shrink the vma to just the new range */
2133 return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
2134}
1/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/backing-dev.h>
14#include <linux/mm.h>
15#include <linux/vmacache.h>
16#include <linux/shm.h>
17#include <linux/mman.h>
18#include <linux/pagemap.h>
19#include <linux/swap.h>
20#include <linux/syscalls.h>
21#include <linux/capability.h>
22#include <linux/init.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/security.h>
27#include <linux/hugetlb.h>
28#include <linux/shmem_fs.h>
29#include <linux/profile.h>
30#include <linux/export.h>
31#include <linux/mount.h>
32#include <linux/mempolicy.h>
33#include <linux/rmap.h>
34#include <linux/mmu_notifier.h>
35#include <linux/mmdebug.h>
36#include <linux/perf_event.h>
37#include <linux/audit.h>
38#include <linux/khugepaged.h>
39#include <linux/uprobes.h>
40#include <linux/rbtree_augmented.h>
41#include <linux/notifier.h>
42#include <linux/memory.h>
43#include <linux/printk.h>
44#include <linux/userfaultfd_k.h>
45#include <linux/moduleparam.h>
46#include <linux/pkeys.h>
47
48#include <linux/uaccess.h>
49#include <asm/cacheflush.h>
50#include <asm/tlb.h>
51#include <asm/mmu_context.h>
52
53#include "internal.h"
54
55#ifndef arch_mmap_check
56#define arch_mmap_check(addr, len, flags) (0)
57#endif
58
59#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
60const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
61const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
62int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
63#endif
64#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
65const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
66const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
67int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
68#endif
69
70static bool ignore_rlimit_data;
71core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
72
73static void unmap_region(struct mm_struct *mm,
74 struct vm_area_struct *vma, struct vm_area_struct *prev,
75 unsigned long start, unsigned long end);
76
77/* description of effects of mapping type and prot in current implementation.
78 * this is due to the limited x86 page protection hardware. The expected
79 * behavior is in parens:
80 *
81 * map_type prot
82 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
83 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
84 * w: (no) no w: (no) no w: (yes) yes w: (no) no
85 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
86 *
87 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
88 * w: (no) no w: (no) no w: (copy) copy w: (no) no
89 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
90 *
91 * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
92 * MAP_PRIVATE:
93 * r: (no) no
94 * w: (no) no
95 * x: (yes) yes
96 */
97pgprot_t protection_map[16] = {
98 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
99 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
100};
101
102pgprot_t vm_get_page_prot(unsigned long vm_flags)
103{
104 return __pgprot(pgprot_val(protection_map[vm_flags &
105 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
106 pgprot_val(arch_vm_get_page_prot(vm_flags)));
107}
108EXPORT_SYMBOL(vm_get_page_prot);
109
110static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
111{
112 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
113}
114
115/* Update vma->vm_page_prot to reflect vma->vm_flags. */
116void vma_set_page_prot(struct vm_area_struct *vma)
117{
118 unsigned long vm_flags = vma->vm_flags;
119 pgprot_t vm_page_prot;
120
121 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
122 if (vma_wants_writenotify(vma, vm_page_prot)) {
123 vm_flags &= ~VM_SHARED;
124 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
125 }
126 /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
127 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
128}
129
130/*
131 * Requires inode->i_mapping->i_mmap_rwsem
132 */
133static void __remove_shared_vm_struct(struct vm_area_struct *vma,
134 struct file *file, struct address_space *mapping)
135{
136 if (vma->vm_flags & VM_DENYWRITE)
137 atomic_inc(&file_inode(file)->i_writecount);
138 if (vma->vm_flags & VM_SHARED)
139 mapping_unmap_writable(mapping);
140
141 flush_dcache_mmap_lock(mapping);
142 vma_interval_tree_remove(vma, &mapping->i_mmap);
143 flush_dcache_mmap_unlock(mapping);
144}
145
146/*
147 * Unlink a file-based vm structure from its interval tree, to hide
148 * vma from rmap and vmtruncate before freeing its page tables.
149 */
150void unlink_file_vma(struct vm_area_struct *vma)
151{
152 struct file *file = vma->vm_file;
153
154 if (file) {
155 struct address_space *mapping = file->f_mapping;
156 i_mmap_lock_write(mapping);
157 __remove_shared_vm_struct(vma, file, mapping);
158 i_mmap_unlock_write(mapping);
159 }
160}
161
162/*
163 * Close a vm structure and free it, returning the next.
164 */
165static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
166{
167 struct vm_area_struct *next = vma->vm_next;
168
169 might_sleep();
170 if (vma->vm_ops && vma->vm_ops->close)
171 vma->vm_ops->close(vma);
172 if (vma->vm_file)
173 fput(vma->vm_file);
174 mpol_put(vma_policy(vma));
175 kmem_cache_free(vm_area_cachep, vma);
176 return next;
177}
178
179static int do_brk(unsigned long addr, unsigned long len);
180
181SYSCALL_DEFINE1(brk, unsigned long, brk)
182{
183 unsigned long retval;
184 unsigned long newbrk, oldbrk;
185 struct mm_struct *mm = current->mm;
186 unsigned long min_brk;
187 bool populate;
188
189 if (down_write_killable(&mm->mmap_sem))
190 return -EINTR;
191
192#ifdef CONFIG_COMPAT_BRK
193 /*
194 * CONFIG_COMPAT_BRK can still be overridden by setting
195 * randomize_va_space to 2, which will still cause mm->start_brk
196 * to be arbitrarily shifted
197 */
198 if (current->brk_randomized)
199 min_brk = mm->start_brk;
200 else
201 min_brk = mm->end_data;
202#else
203 min_brk = mm->start_brk;
204#endif
205 if (brk < min_brk)
206 goto out;
207
208 /*
209 * Check against rlimit here. If this check is done later after the test
210 * of oldbrk with newbrk then it can escape the test and let the data
211 * segment grow beyond its set limit the in case where the limit is
212 * not page aligned -Ram Gupta
213 */
214 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
215 mm->end_data, mm->start_data))
216 goto out;
217
218 newbrk = PAGE_ALIGN(brk);
219 oldbrk = PAGE_ALIGN(mm->brk);
220 if (oldbrk == newbrk)
221 goto set_brk;
222
223 /* Always allow shrinking brk. */
224 if (brk <= mm->brk) {
225 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
226 goto set_brk;
227 goto out;
228 }
229
230 /* Check against existing mmap mappings. */
231 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
232 goto out;
233
234 /* Ok, looks good - let it rip. */
235 if (do_brk(oldbrk, newbrk-oldbrk) < 0)
236 goto out;
237
238set_brk:
239 mm->brk = brk;
240 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
241 up_write(&mm->mmap_sem);
242 if (populate)
243 mm_populate(oldbrk, newbrk - oldbrk);
244 return brk;
245
246out:
247 retval = mm->brk;
248 up_write(&mm->mmap_sem);
249 return retval;
250}
251
252static long vma_compute_subtree_gap(struct vm_area_struct *vma)
253{
254 unsigned long max, subtree_gap;
255 max = vma->vm_start;
256 if (vma->vm_prev)
257 max -= vma->vm_prev->vm_end;
258 if (vma->vm_rb.rb_left) {
259 subtree_gap = rb_entry(vma->vm_rb.rb_left,
260 struct vm_area_struct, vm_rb)->rb_subtree_gap;
261 if (subtree_gap > max)
262 max = subtree_gap;
263 }
264 if (vma->vm_rb.rb_right) {
265 subtree_gap = rb_entry(vma->vm_rb.rb_right,
266 struct vm_area_struct, vm_rb)->rb_subtree_gap;
267 if (subtree_gap > max)
268 max = subtree_gap;
269 }
270 return max;
271}
272
273#ifdef CONFIG_DEBUG_VM_RB
274static int browse_rb(struct mm_struct *mm)
275{
276 struct rb_root *root = &mm->mm_rb;
277 int i = 0, j, bug = 0;
278 struct rb_node *nd, *pn = NULL;
279 unsigned long prev = 0, pend = 0;
280
281 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
282 struct vm_area_struct *vma;
283 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
284 if (vma->vm_start < prev) {
285 pr_emerg("vm_start %lx < prev %lx\n",
286 vma->vm_start, prev);
287 bug = 1;
288 }
289 if (vma->vm_start < pend) {
290 pr_emerg("vm_start %lx < pend %lx\n",
291 vma->vm_start, pend);
292 bug = 1;
293 }
294 if (vma->vm_start > vma->vm_end) {
295 pr_emerg("vm_start %lx > vm_end %lx\n",
296 vma->vm_start, vma->vm_end);
297 bug = 1;
298 }
299 spin_lock(&mm->page_table_lock);
300 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
301 pr_emerg("free gap %lx, correct %lx\n",
302 vma->rb_subtree_gap,
303 vma_compute_subtree_gap(vma));
304 bug = 1;
305 }
306 spin_unlock(&mm->page_table_lock);
307 i++;
308 pn = nd;
309 prev = vma->vm_start;
310 pend = vma->vm_end;
311 }
312 j = 0;
313 for (nd = pn; nd; nd = rb_prev(nd))
314 j++;
315 if (i != j) {
316 pr_emerg("backwards %d, forwards %d\n", j, i);
317 bug = 1;
318 }
319 return bug ? -1 : i;
320}
321
322static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
323{
324 struct rb_node *nd;
325
326 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
327 struct vm_area_struct *vma;
328 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
329 VM_BUG_ON_VMA(vma != ignore &&
330 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
331 vma);
332 }
333}
334
335static void validate_mm(struct mm_struct *mm)
336{
337 int bug = 0;
338 int i = 0;
339 unsigned long highest_address = 0;
340 struct vm_area_struct *vma = mm->mmap;
341
342 while (vma) {
343 struct anon_vma *anon_vma = vma->anon_vma;
344 struct anon_vma_chain *avc;
345
346 if (anon_vma) {
347 anon_vma_lock_read(anon_vma);
348 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
349 anon_vma_interval_tree_verify(avc);
350 anon_vma_unlock_read(anon_vma);
351 }
352
353 highest_address = vma->vm_end;
354 vma = vma->vm_next;
355 i++;
356 }
357 if (i != mm->map_count) {
358 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
359 bug = 1;
360 }
361 if (highest_address != mm->highest_vm_end) {
362 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
363 mm->highest_vm_end, highest_address);
364 bug = 1;
365 }
366 i = browse_rb(mm);
367 if (i != mm->map_count) {
368 if (i != -1)
369 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
370 bug = 1;
371 }
372 VM_BUG_ON_MM(bug, mm);
373}
374#else
375#define validate_mm_rb(root, ignore) do { } while (0)
376#define validate_mm(mm) do { } while (0)
377#endif
378
379RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
380 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
381
382/*
383 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
384 * vma->vm_prev->vm_end values changed, without modifying the vma's position
385 * in the rbtree.
386 */
387static void vma_gap_update(struct vm_area_struct *vma)
388{
389 /*
390 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
391 * function that does exacltly what we want.
392 */
393 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
394}
395
396static inline void vma_rb_insert(struct vm_area_struct *vma,
397 struct rb_root *root)
398{
399 /* All rb_subtree_gap values must be consistent prior to insertion */
400 validate_mm_rb(root, NULL);
401
402 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
403}
404
405static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
406{
407 /*
408 * Note rb_erase_augmented is a fairly large inline function,
409 * so make sure we instantiate it only once with our desired
410 * augmented rbtree callbacks.
411 */
412 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
413}
414
415static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
416 struct rb_root *root,
417 struct vm_area_struct *ignore)
418{
419 /*
420 * All rb_subtree_gap values must be consistent prior to erase,
421 * with the possible exception of the "next" vma being erased if
422 * next->vm_start was reduced.
423 */
424 validate_mm_rb(root, ignore);
425
426 __vma_rb_erase(vma, root);
427}
428
429static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
430 struct rb_root *root)
431{
432 /*
433 * All rb_subtree_gap values must be consistent prior to erase,
434 * with the possible exception of the vma being erased.
435 */
436 validate_mm_rb(root, vma);
437
438 __vma_rb_erase(vma, root);
439}
440
441/*
442 * vma has some anon_vma assigned, and is already inserted on that
443 * anon_vma's interval trees.
444 *
445 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
446 * vma must be removed from the anon_vma's interval trees using
447 * anon_vma_interval_tree_pre_update_vma().
448 *
449 * After the update, the vma will be reinserted using
450 * anon_vma_interval_tree_post_update_vma().
451 *
452 * The entire update must be protected by exclusive mmap_sem and by
453 * the root anon_vma's mutex.
454 */
455static inline void
456anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
457{
458 struct anon_vma_chain *avc;
459
460 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
461 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
462}
463
464static inline void
465anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
466{
467 struct anon_vma_chain *avc;
468
469 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
470 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
471}
472
473static int find_vma_links(struct mm_struct *mm, unsigned long addr,
474 unsigned long end, struct vm_area_struct **pprev,
475 struct rb_node ***rb_link, struct rb_node **rb_parent)
476{
477 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
478
479 __rb_link = &mm->mm_rb.rb_node;
480 rb_prev = __rb_parent = NULL;
481
482 while (*__rb_link) {
483 struct vm_area_struct *vma_tmp;
484
485 __rb_parent = *__rb_link;
486 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
487
488 if (vma_tmp->vm_end > addr) {
489 /* Fail if an existing vma overlaps the area */
490 if (vma_tmp->vm_start < end)
491 return -ENOMEM;
492 __rb_link = &__rb_parent->rb_left;
493 } else {
494 rb_prev = __rb_parent;
495 __rb_link = &__rb_parent->rb_right;
496 }
497 }
498
499 *pprev = NULL;
500 if (rb_prev)
501 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
502 *rb_link = __rb_link;
503 *rb_parent = __rb_parent;
504 return 0;
505}
506
507static unsigned long count_vma_pages_range(struct mm_struct *mm,
508 unsigned long addr, unsigned long end)
509{
510 unsigned long nr_pages = 0;
511 struct vm_area_struct *vma;
512
513 /* Find first overlaping mapping */
514 vma = find_vma_intersection(mm, addr, end);
515 if (!vma)
516 return 0;
517
518 nr_pages = (min(end, vma->vm_end) -
519 max(addr, vma->vm_start)) >> PAGE_SHIFT;
520
521 /* Iterate over the rest of the overlaps */
522 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
523 unsigned long overlap_len;
524
525 if (vma->vm_start > end)
526 break;
527
528 overlap_len = min(end, vma->vm_end) - vma->vm_start;
529 nr_pages += overlap_len >> PAGE_SHIFT;
530 }
531
532 return nr_pages;
533}
534
535void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
536 struct rb_node **rb_link, struct rb_node *rb_parent)
537{
538 /* Update tracking information for the gap following the new vma. */
539 if (vma->vm_next)
540 vma_gap_update(vma->vm_next);
541 else
542 mm->highest_vm_end = vma->vm_end;
543
544 /*
545 * vma->vm_prev wasn't known when we followed the rbtree to find the
546 * correct insertion point for that vma. As a result, we could not
547 * update the vma vm_rb parents rb_subtree_gap values on the way down.
548 * So, we first insert the vma with a zero rb_subtree_gap value
549 * (to be consistent with what we did on the way down), and then
550 * immediately update the gap to the correct value. Finally we
551 * rebalance the rbtree after all augmented values have been set.
552 */
553 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
554 vma->rb_subtree_gap = 0;
555 vma_gap_update(vma);
556 vma_rb_insert(vma, &mm->mm_rb);
557}
558
559static void __vma_link_file(struct vm_area_struct *vma)
560{
561 struct file *file;
562
563 file = vma->vm_file;
564 if (file) {
565 struct address_space *mapping = file->f_mapping;
566
567 if (vma->vm_flags & VM_DENYWRITE)
568 atomic_dec(&file_inode(file)->i_writecount);
569 if (vma->vm_flags & VM_SHARED)
570 atomic_inc(&mapping->i_mmap_writable);
571
572 flush_dcache_mmap_lock(mapping);
573 vma_interval_tree_insert(vma, &mapping->i_mmap);
574 flush_dcache_mmap_unlock(mapping);
575 }
576}
577
578static void
579__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
580 struct vm_area_struct *prev, struct rb_node **rb_link,
581 struct rb_node *rb_parent)
582{
583 __vma_link_list(mm, vma, prev, rb_parent);
584 __vma_link_rb(mm, vma, rb_link, rb_parent);
585}
586
587static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
588 struct vm_area_struct *prev, struct rb_node **rb_link,
589 struct rb_node *rb_parent)
590{
591 struct address_space *mapping = NULL;
592
593 if (vma->vm_file) {
594 mapping = vma->vm_file->f_mapping;
595 i_mmap_lock_write(mapping);
596 }
597
598 __vma_link(mm, vma, prev, rb_link, rb_parent);
599 __vma_link_file(vma);
600
601 if (mapping)
602 i_mmap_unlock_write(mapping);
603
604 mm->map_count++;
605 validate_mm(mm);
606}
607
608/*
609 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
610 * mm's list and rbtree. It has already been inserted into the interval tree.
611 */
612static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
613{
614 struct vm_area_struct *prev;
615 struct rb_node **rb_link, *rb_parent;
616
617 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
618 &prev, &rb_link, &rb_parent))
619 BUG();
620 __vma_link(mm, vma, prev, rb_link, rb_parent);
621 mm->map_count++;
622}
623
624static __always_inline void __vma_unlink_common(struct mm_struct *mm,
625 struct vm_area_struct *vma,
626 struct vm_area_struct *prev,
627 bool has_prev,
628 struct vm_area_struct *ignore)
629{
630 struct vm_area_struct *next;
631
632 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
633 next = vma->vm_next;
634 if (has_prev)
635 prev->vm_next = next;
636 else {
637 prev = vma->vm_prev;
638 if (prev)
639 prev->vm_next = next;
640 else
641 mm->mmap = next;
642 }
643 if (next)
644 next->vm_prev = prev;
645
646 /* Kill the cache */
647 vmacache_invalidate(mm);
648}
649
650static inline void __vma_unlink_prev(struct mm_struct *mm,
651 struct vm_area_struct *vma,
652 struct vm_area_struct *prev)
653{
654 __vma_unlink_common(mm, vma, prev, true, vma);
655}
656
657/*
658 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
659 * is already present in an i_mmap tree without adjusting the tree.
660 * The following helper function should be used when such adjustments
661 * are necessary. The "insert" vma (if any) is to be inserted
662 * before we drop the necessary locks.
663 */
664int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
665 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
666 struct vm_area_struct *expand)
667{
668 struct mm_struct *mm = vma->vm_mm;
669 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
670 struct address_space *mapping = NULL;
671 struct rb_root *root = NULL;
672 struct anon_vma *anon_vma = NULL;
673 struct file *file = vma->vm_file;
674 bool start_changed = false, end_changed = false;
675 long adjust_next = 0;
676 int remove_next = 0;
677
678 if (next && !insert) {
679 struct vm_area_struct *exporter = NULL, *importer = NULL;
680
681 if (end >= next->vm_end) {
682 /*
683 * vma expands, overlapping all the next, and
684 * perhaps the one after too (mprotect case 6).
685 * The only other cases that gets here are
686 * case 1, case 7 and case 8.
687 */
688 if (next == expand) {
689 /*
690 * The only case where we don't expand "vma"
691 * and we expand "next" instead is case 8.
692 */
693 VM_WARN_ON(end != next->vm_end);
694 /*
695 * remove_next == 3 means we're
696 * removing "vma" and that to do so we
697 * swapped "vma" and "next".
698 */
699 remove_next = 3;
700 VM_WARN_ON(file != next->vm_file);
701 swap(vma, next);
702 } else {
703 VM_WARN_ON(expand != vma);
704 /*
705 * case 1, 6, 7, remove_next == 2 is case 6,
706 * remove_next == 1 is case 1 or 7.
707 */
708 remove_next = 1 + (end > next->vm_end);
709 VM_WARN_ON(remove_next == 2 &&
710 end != next->vm_next->vm_end);
711 VM_WARN_ON(remove_next == 1 &&
712 end != next->vm_end);
713 /* trim end to next, for case 6 first pass */
714 end = next->vm_end;
715 }
716
717 exporter = next;
718 importer = vma;
719
720 /*
721 * If next doesn't have anon_vma, import from vma after
722 * next, if the vma overlaps with it.
723 */
724 if (remove_next == 2 && !next->anon_vma)
725 exporter = next->vm_next;
726
727 } else if (end > next->vm_start) {
728 /*
729 * vma expands, overlapping part of the next:
730 * mprotect case 5 shifting the boundary up.
731 */
732 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
733 exporter = next;
734 importer = vma;
735 VM_WARN_ON(expand != importer);
736 } else if (end < vma->vm_end) {
737 /*
738 * vma shrinks, and !insert tells it's not
739 * split_vma inserting another: so it must be
740 * mprotect case 4 shifting the boundary down.
741 */
742 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
743 exporter = vma;
744 importer = next;
745 VM_WARN_ON(expand != importer);
746 }
747
748 /*
749 * Easily overlooked: when mprotect shifts the boundary,
750 * make sure the expanding vma has anon_vma set if the
751 * shrinking vma had, to cover any anon pages imported.
752 */
753 if (exporter && exporter->anon_vma && !importer->anon_vma) {
754 int error;
755
756 importer->anon_vma = exporter->anon_vma;
757 error = anon_vma_clone(importer, exporter);
758 if (error)
759 return error;
760 }
761 }
762again:
763 vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
764
765 if (file) {
766 mapping = file->f_mapping;
767 root = &mapping->i_mmap;
768 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
769
770 if (adjust_next)
771 uprobe_munmap(next, next->vm_start, next->vm_end);
772
773 i_mmap_lock_write(mapping);
774 if (insert) {
775 /*
776 * Put into interval tree now, so instantiated pages
777 * are visible to arm/parisc __flush_dcache_page
778 * throughout; but we cannot insert into address
779 * space until vma start or end is updated.
780 */
781 __vma_link_file(insert);
782 }
783 }
784
785 anon_vma = vma->anon_vma;
786 if (!anon_vma && adjust_next)
787 anon_vma = next->anon_vma;
788 if (anon_vma) {
789 VM_WARN_ON(adjust_next && next->anon_vma &&
790 anon_vma != next->anon_vma);
791 anon_vma_lock_write(anon_vma);
792 anon_vma_interval_tree_pre_update_vma(vma);
793 if (adjust_next)
794 anon_vma_interval_tree_pre_update_vma(next);
795 }
796
797 if (root) {
798 flush_dcache_mmap_lock(mapping);
799 vma_interval_tree_remove(vma, root);
800 if (adjust_next)
801 vma_interval_tree_remove(next, root);
802 }
803
804 if (start != vma->vm_start) {
805 vma->vm_start = start;
806 start_changed = true;
807 }
808 if (end != vma->vm_end) {
809 vma->vm_end = end;
810 end_changed = true;
811 }
812 vma->vm_pgoff = pgoff;
813 if (adjust_next) {
814 next->vm_start += adjust_next << PAGE_SHIFT;
815 next->vm_pgoff += adjust_next;
816 }
817
818 if (root) {
819 if (adjust_next)
820 vma_interval_tree_insert(next, root);
821 vma_interval_tree_insert(vma, root);
822 flush_dcache_mmap_unlock(mapping);
823 }
824
825 if (remove_next) {
826 /*
827 * vma_merge has merged next into vma, and needs
828 * us to remove next before dropping the locks.
829 */
830 if (remove_next != 3)
831 __vma_unlink_prev(mm, next, vma);
832 else
833 /*
834 * vma is not before next if they've been
835 * swapped.
836 *
837 * pre-swap() next->vm_start was reduced so
838 * tell validate_mm_rb to ignore pre-swap()
839 * "next" (which is stored in post-swap()
840 * "vma").
841 */
842 __vma_unlink_common(mm, next, NULL, false, vma);
843 if (file)
844 __remove_shared_vm_struct(next, file, mapping);
845 } else if (insert) {
846 /*
847 * split_vma has split insert from vma, and needs
848 * us to insert it before dropping the locks
849 * (it may either follow vma or precede it).
850 */
851 __insert_vm_struct(mm, insert);
852 } else {
853 if (start_changed)
854 vma_gap_update(vma);
855 if (end_changed) {
856 if (!next)
857 mm->highest_vm_end = end;
858 else if (!adjust_next)
859 vma_gap_update(next);
860 }
861 }
862
863 if (anon_vma) {
864 anon_vma_interval_tree_post_update_vma(vma);
865 if (adjust_next)
866 anon_vma_interval_tree_post_update_vma(next);
867 anon_vma_unlock_write(anon_vma);
868 }
869 if (mapping)
870 i_mmap_unlock_write(mapping);
871
872 if (root) {
873 uprobe_mmap(vma);
874
875 if (adjust_next)
876 uprobe_mmap(next);
877 }
878
879 if (remove_next) {
880 if (file) {
881 uprobe_munmap(next, next->vm_start, next->vm_end);
882 fput(file);
883 }
884 if (next->anon_vma)
885 anon_vma_merge(vma, next);
886 mm->map_count--;
887 mpol_put(vma_policy(next));
888 kmem_cache_free(vm_area_cachep, next);
889 /*
890 * In mprotect's case 6 (see comments on vma_merge),
891 * we must remove another next too. It would clutter
892 * up the code too much to do both in one go.
893 */
894 if (remove_next != 3) {
895 /*
896 * If "next" was removed and vma->vm_end was
897 * expanded (up) over it, in turn
898 * "next->vm_prev->vm_end" changed and the
899 * "vma->vm_next" gap must be updated.
900 */
901 next = vma->vm_next;
902 } else {
903 /*
904 * For the scope of the comment "next" and
905 * "vma" considered pre-swap(): if "vma" was
906 * removed, next->vm_start was expanded (down)
907 * over it and the "next" gap must be updated.
908 * Because of the swap() the post-swap() "vma"
909 * actually points to pre-swap() "next"
910 * (post-swap() "next" as opposed is now a
911 * dangling pointer).
912 */
913 next = vma;
914 }
915 if (remove_next == 2) {
916 remove_next = 1;
917 end = next->vm_end;
918 goto again;
919 }
920 else if (next)
921 vma_gap_update(next);
922 else {
923 /*
924 * If remove_next == 2 we obviously can't
925 * reach this path.
926 *
927 * If remove_next == 3 we can't reach this
928 * path because pre-swap() next is always not
929 * NULL. pre-swap() "next" is not being
930 * removed and its next->vm_end is not altered
931 * (and furthermore "end" already matches
932 * next->vm_end in remove_next == 3).
933 *
934 * We reach this only in the remove_next == 1
935 * case if the "next" vma that was removed was
936 * the highest vma of the mm. However in such
937 * case next->vm_end == "end" and the extended
938 * "vma" has vma->vm_end == next->vm_end so
939 * mm->highest_vm_end doesn't need any update
940 * in remove_next == 1 case.
941 */
942 VM_WARN_ON(mm->highest_vm_end != end);
943 }
944 }
945 if (insert && file)
946 uprobe_mmap(insert);
947
948 validate_mm(mm);
949
950 return 0;
951}
952
953/*
954 * If the vma has a ->close operation then the driver probably needs to release
955 * per-vma resources, so we don't attempt to merge those.
956 */
957static inline int is_mergeable_vma(struct vm_area_struct *vma,
958 struct file *file, unsigned long vm_flags,
959 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
960{
961 /*
962 * VM_SOFTDIRTY should not prevent from VMA merging, if we
963 * match the flags but dirty bit -- the caller should mark
964 * merged VMA as dirty. If dirty bit won't be excluded from
965 * comparison, we increase pressue on the memory system forcing
966 * the kernel to generate new VMAs when old one could be
967 * extended instead.
968 */
969 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
970 return 0;
971 if (vma->vm_file != file)
972 return 0;
973 if (vma->vm_ops && vma->vm_ops->close)
974 return 0;
975 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
976 return 0;
977 return 1;
978}
979
980static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
981 struct anon_vma *anon_vma2,
982 struct vm_area_struct *vma)
983{
984 /*
985 * The list_is_singular() test is to avoid merging VMA cloned from
986 * parents. This can improve scalability caused by anon_vma lock.
987 */
988 if ((!anon_vma1 || !anon_vma2) && (!vma ||
989 list_is_singular(&vma->anon_vma_chain)))
990 return 1;
991 return anon_vma1 == anon_vma2;
992}
993
994/*
995 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
996 * in front of (at a lower virtual address and file offset than) the vma.
997 *
998 * We cannot merge two vmas if they have differently assigned (non-NULL)
999 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1000 *
1001 * We don't check here for the merged mmap wrapping around the end of pagecache
1002 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
1003 * wrap, nor mmaps which cover the final page at index -1UL.
1004 */
1005static int
1006can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1007 struct anon_vma *anon_vma, struct file *file,
1008 pgoff_t vm_pgoff,
1009 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1010{
1011 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1012 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1013 if (vma->vm_pgoff == vm_pgoff)
1014 return 1;
1015 }
1016 return 0;
1017}
1018
1019/*
1020 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1021 * beyond (at a higher virtual address and file offset than) the vma.
1022 *
1023 * We cannot merge two vmas if they have differently assigned (non-NULL)
1024 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1025 */
1026static int
1027can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1028 struct anon_vma *anon_vma, struct file *file,
1029 pgoff_t vm_pgoff,
1030 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1031{
1032 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1033 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1034 pgoff_t vm_pglen;
1035 vm_pglen = vma_pages(vma);
1036 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1037 return 1;
1038 }
1039 return 0;
1040}
1041
1042/*
1043 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1044 * whether that can be merged with its predecessor or its successor.
1045 * Or both (it neatly fills a hole).
1046 *
1047 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1048 * certain not to be mapped by the time vma_merge is called; but when
1049 * called for mprotect, it is certain to be already mapped (either at
1050 * an offset within prev, or at the start of next), and the flags of
1051 * this area are about to be changed to vm_flags - and the no-change
1052 * case has already been eliminated.
1053 *
1054 * The following mprotect cases have to be considered, where AAAA is
1055 * the area passed down from mprotect_fixup, never extending beyond one
1056 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1057 *
1058 * AAAA AAAA AAAA AAAA
1059 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1060 * cannot merge might become might become might become
1061 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1062 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1063 * mremap move: PPPPXXXXXXXX 8
1064 * AAAA
1065 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1066 * might become case 1 below case 2 below case 3 below
1067 *
1068 * It is important for case 8 that the the vma NNNN overlapping the
1069 * region AAAA is never going to extended over XXXX. Instead XXXX must
1070 * be extended in region AAAA and NNNN must be removed. This way in
1071 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1072 * rmap_locks, the properties of the merged vma will be already
1073 * correct for the whole merged range. Some of those properties like
1074 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1075 * be correct for the whole merged range immediately after the
1076 * rmap_locks are released. Otherwise if XXXX would be removed and
1077 * NNNN would be extended over the XXXX range, remove_migration_ptes
1078 * or other rmap walkers (if working on addresses beyond the "end"
1079 * parameter) may establish ptes with the wrong permissions of NNNN
1080 * instead of the right permissions of XXXX.
1081 */
1082struct vm_area_struct *vma_merge(struct mm_struct *mm,
1083 struct vm_area_struct *prev, unsigned long addr,
1084 unsigned long end, unsigned long vm_flags,
1085 struct anon_vma *anon_vma, struct file *file,
1086 pgoff_t pgoff, struct mempolicy *policy,
1087 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1088{
1089 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1090 struct vm_area_struct *area, *next;
1091 int err;
1092
1093 /*
1094 * We later require that vma->vm_flags == vm_flags,
1095 * so this tests vma->vm_flags & VM_SPECIAL, too.
1096 */
1097 if (vm_flags & VM_SPECIAL)
1098 return NULL;
1099
1100 if (prev)
1101 next = prev->vm_next;
1102 else
1103 next = mm->mmap;
1104 area = next;
1105 if (area && area->vm_end == end) /* cases 6, 7, 8 */
1106 next = next->vm_next;
1107
1108 /* verify some invariant that must be enforced by the caller */
1109 VM_WARN_ON(prev && addr <= prev->vm_start);
1110 VM_WARN_ON(area && end > area->vm_end);
1111 VM_WARN_ON(addr >= end);
1112
1113 /*
1114 * Can it merge with the predecessor?
1115 */
1116 if (prev && prev->vm_end == addr &&
1117 mpol_equal(vma_policy(prev), policy) &&
1118 can_vma_merge_after(prev, vm_flags,
1119 anon_vma, file, pgoff,
1120 vm_userfaultfd_ctx)) {
1121 /*
1122 * OK, it can. Can we now merge in the successor as well?
1123 */
1124 if (next && end == next->vm_start &&
1125 mpol_equal(policy, vma_policy(next)) &&
1126 can_vma_merge_before(next, vm_flags,
1127 anon_vma, file,
1128 pgoff+pglen,
1129 vm_userfaultfd_ctx) &&
1130 is_mergeable_anon_vma(prev->anon_vma,
1131 next->anon_vma, NULL)) {
1132 /* cases 1, 6 */
1133 err = __vma_adjust(prev, prev->vm_start,
1134 next->vm_end, prev->vm_pgoff, NULL,
1135 prev);
1136 } else /* cases 2, 5, 7 */
1137 err = __vma_adjust(prev, prev->vm_start,
1138 end, prev->vm_pgoff, NULL, prev);
1139 if (err)
1140 return NULL;
1141 khugepaged_enter_vma_merge(prev, vm_flags);
1142 return prev;
1143 }
1144
1145 /*
1146 * Can this new request be merged in front of next?
1147 */
1148 if (next && end == next->vm_start &&
1149 mpol_equal(policy, vma_policy(next)) &&
1150 can_vma_merge_before(next, vm_flags,
1151 anon_vma, file, pgoff+pglen,
1152 vm_userfaultfd_ctx)) {
1153 if (prev && addr < prev->vm_end) /* case 4 */
1154 err = __vma_adjust(prev, prev->vm_start,
1155 addr, prev->vm_pgoff, NULL, next);
1156 else { /* cases 3, 8 */
1157 err = __vma_adjust(area, addr, next->vm_end,
1158 next->vm_pgoff - pglen, NULL, next);
1159 /*
1160 * In case 3 area is already equal to next and
1161 * this is a noop, but in case 8 "area" has
1162 * been removed and next was expanded over it.
1163 */
1164 area = next;
1165 }
1166 if (err)
1167 return NULL;
1168 khugepaged_enter_vma_merge(area, vm_flags);
1169 return area;
1170 }
1171
1172 return NULL;
1173}
1174
1175/*
1176 * Rough compatbility check to quickly see if it's even worth looking
1177 * at sharing an anon_vma.
1178 *
1179 * They need to have the same vm_file, and the flags can only differ
1180 * in things that mprotect may change.
1181 *
1182 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1183 * we can merge the two vma's. For example, we refuse to merge a vma if
1184 * there is a vm_ops->close() function, because that indicates that the
1185 * driver is doing some kind of reference counting. But that doesn't
1186 * really matter for the anon_vma sharing case.
1187 */
1188static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1189{
1190 return a->vm_end == b->vm_start &&
1191 mpol_equal(vma_policy(a), vma_policy(b)) &&
1192 a->vm_file == b->vm_file &&
1193 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1194 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1195}
1196
1197/*
1198 * Do some basic sanity checking to see if we can re-use the anon_vma
1199 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1200 * the same as 'old', the other will be the new one that is trying
1201 * to share the anon_vma.
1202 *
1203 * NOTE! This runs with mm_sem held for reading, so it is possible that
1204 * the anon_vma of 'old' is concurrently in the process of being set up
1205 * by another page fault trying to merge _that_. But that's ok: if it
1206 * is being set up, that automatically means that it will be a singleton
1207 * acceptable for merging, so we can do all of this optimistically. But
1208 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1209 *
1210 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1211 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1212 * is to return an anon_vma that is "complex" due to having gone through
1213 * a fork).
1214 *
1215 * We also make sure that the two vma's are compatible (adjacent,
1216 * and with the same memory policies). That's all stable, even with just
1217 * a read lock on the mm_sem.
1218 */
1219static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1220{
1221 if (anon_vma_compatible(a, b)) {
1222 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1223
1224 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1225 return anon_vma;
1226 }
1227 return NULL;
1228}
1229
1230/*
1231 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1232 * neighbouring vmas for a suitable anon_vma, before it goes off
1233 * to allocate a new anon_vma. It checks because a repetitive
1234 * sequence of mprotects and faults may otherwise lead to distinct
1235 * anon_vmas being allocated, preventing vma merge in subsequent
1236 * mprotect.
1237 */
1238struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1239{
1240 struct anon_vma *anon_vma;
1241 struct vm_area_struct *near;
1242
1243 near = vma->vm_next;
1244 if (!near)
1245 goto try_prev;
1246
1247 anon_vma = reusable_anon_vma(near, vma, near);
1248 if (anon_vma)
1249 return anon_vma;
1250try_prev:
1251 near = vma->vm_prev;
1252 if (!near)
1253 goto none;
1254
1255 anon_vma = reusable_anon_vma(near, near, vma);
1256 if (anon_vma)
1257 return anon_vma;
1258none:
1259 /*
1260 * There's no absolute need to look only at touching neighbours:
1261 * we could search further afield for "compatible" anon_vmas.
1262 * But it would probably just be a waste of time searching,
1263 * or lead to too many vmas hanging off the same anon_vma.
1264 * We're trying to allow mprotect remerging later on,
1265 * not trying to minimize memory used for anon_vmas.
1266 */
1267 return NULL;
1268}
1269
1270/*
1271 * If a hint addr is less than mmap_min_addr change hint to be as
1272 * low as possible but still greater than mmap_min_addr
1273 */
1274static inline unsigned long round_hint_to_min(unsigned long hint)
1275{
1276 hint &= PAGE_MASK;
1277 if (((void *)hint != NULL) &&
1278 (hint < mmap_min_addr))
1279 return PAGE_ALIGN(mmap_min_addr);
1280 return hint;
1281}
1282
1283static inline int mlock_future_check(struct mm_struct *mm,
1284 unsigned long flags,
1285 unsigned long len)
1286{
1287 unsigned long locked, lock_limit;
1288
1289 /* mlock MCL_FUTURE? */
1290 if (flags & VM_LOCKED) {
1291 locked = len >> PAGE_SHIFT;
1292 locked += mm->locked_vm;
1293 lock_limit = rlimit(RLIMIT_MEMLOCK);
1294 lock_limit >>= PAGE_SHIFT;
1295 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1296 return -EAGAIN;
1297 }
1298 return 0;
1299}
1300
1301/*
1302 * The caller must hold down_write(¤t->mm->mmap_sem).
1303 */
1304unsigned long do_mmap(struct file *file, unsigned long addr,
1305 unsigned long len, unsigned long prot,
1306 unsigned long flags, vm_flags_t vm_flags,
1307 unsigned long pgoff, unsigned long *populate)
1308{
1309 struct mm_struct *mm = current->mm;
1310 int pkey = 0;
1311
1312 *populate = 0;
1313
1314 if (!len)
1315 return -EINVAL;
1316
1317 /*
1318 * Does the application expect PROT_READ to imply PROT_EXEC?
1319 *
1320 * (the exception is when the underlying filesystem is noexec
1321 * mounted, in which case we dont add PROT_EXEC.)
1322 */
1323 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1324 if (!(file && path_noexec(&file->f_path)))
1325 prot |= PROT_EXEC;
1326
1327 if (!(flags & MAP_FIXED))
1328 addr = round_hint_to_min(addr);
1329
1330 /* Careful about overflows.. */
1331 len = PAGE_ALIGN(len);
1332 if (!len)
1333 return -ENOMEM;
1334
1335 /* offset overflow? */
1336 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1337 return -EOVERFLOW;
1338
1339 /* Too many mappings? */
1340 if (mm->map_count > sysctl_max_map_count)
1341 return -ENOMEM;
1342
1343 /* Obtain the address to map to. we verify (or select) it and ensure
1344 * that it represents a valid section of the address space.
1345 */
1346 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1347 if (offset_in_page(addr))
1348 return addr;
1349
1350 if (prot == PROT_EXEC) {
1351 pkey = execute_only_pkey(mm);
1352 if (pkey < 0)
1353 pkey = 0;
1354 }
1355
1356 /* Do simple checking here so the lower-level routines won't have
1357 * to. we assume access permissions have been handled by the open
1358 * of the memory object, so we don't do any here.
1359 */
1360 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1361 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1362
1363 if (flags & MAP_LOCKED)
1364 if (!can_do_mlock())
1365 return -EPERM;
1366
1367 if (mlock_future_check(mm, vm_flags, len))
1368 return -EAGAIN;
1369
1370 if (file) {
1371 struct inode *inode = file_inode(file);
1372
1373 switch (flags & MAP_TYPE) {
1374 case MAP_SHARED:
1375 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1376 return -EACCES;
1377
1378 /*
1379 * Make sure we don't allow writing to an append-only
1380 * file..
1381 */
1382 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1383 return -EACCES;
1384
1385 /*
1386 * Make sure there are no mandatory locks on the file.
1387 */
1388 if (locks_verify_locked(file))
1389 return -EAGAIN;
1390
1391 vm_flags |= VM_SHARED | VM_MAYSHARE;
1392 if (!(file->f_mode & FMODE_WRITE))
1393 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1394
1395 /* fall through */
1396 case MAP_PRIVATE:
1397 if (!(file->f_mode & FMODE_READ))
1398 return -EACCES;
1399 if (path_noexec(&file->f_path)) {
1400 if (vm_flags & VM_EXEC)
1401 return -EPERM;
1402 vm_flags &= ~VM_MAYEXEC;
1403 }
1404
1405 if (!file->f_op->mmap)
1406 return -ENODEV;
1407 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1408 return -EINVAL;
1409 break;
1410
1411 default:
1412 return -EINVAL;
1413 }
1414 } else {
1415 switch (flags & MAP_TYPE) {
1416 case MAP_SHARED:
1417 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1418 return -EINVAL;
1419 /*
1420 * Ignore pgoff.
1421 */
1422 pgoff = 0;
1423 vm_flags |= VM_SHARED | VM_MAYSHARE;
1424 break;
1425 case MAP_PRIVATE:
1426 /*
1427 * Set pgoff according to addr for anon_vma.
1428 */
1429 pgoff = addr >> PAGE_SHIFT;
1430 break;
1431 default:
1432 return -EINVAL;
1433 }
1434 }
1435
1436 /*
1437 * Set 'VM_NORESERVE' if we should not account for the
1438 * memory use of this mapping.
1439 */
1440 if (flags & MAP_NORESERVE) {
1441 /* We honor MAP_NORESERVE if allowed to overcommit */
1442 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1443 vm_flags |= VM_NORESERVE;
1444
1445 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1446 if (file && is_file_hugepages(file))
1447 vm_flags |= VM_NORESERVE;
1448 }
1449
1450 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1451 if (!IS_ERR_VALUE(addr) &&
1452 ((vm_flags & VM_LOCKED) ||
1453 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1454 *populate = len;
1455 return addr;
1456}
1457
1458SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1459 unsigned long, prot, unsigned long, flags,
1460 unsigned long, fd, unsigned long, pgoff)
1461{
1462 struct file *file = NULL;
1463 unsigned long retval;
1464
1465 if (!(flags & MAP_ANONYMOUS)) {
1466 audit_mmap_fd(fd, flags);
1467 file = fget(fd);
1468 if (!file)
1469 return -EBADF;
1470 if (is_file_hugepages(file))
1471 len = ALIGN(len, huge_page_size(hstate_file(file)));
1472 retval = -EINVAL;
1473 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1474 goto out_fput;
1475 } else if (flags & MAP_HUGETLB) {
1476 struct user_struct *user = NULL;
1477 struct hstate *hs;
1478
1479 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1480 if (!hs)
1481 return -EINVAL;
1482
1483 len = ALIGN(len, huge_page_size(hs));
1484 /*
1485 * VM_NORESERVE is used because the reservations will be
1486 * taken when vm_ops->mmap() is called
1487 * A dummy user value is used because we are not locking
1488 * memory so no accounting is necessary
1489 */
1490 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1491 VM_NORESERVE,
1492 &user, HUGETLB_ANONHUGE_INODE,
1493 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1494 if (IS_ERR(file))
1495 return PTR_ERR(file);
1496 }
1497
1498 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1499
1500 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1501out_fput:
1502 if (file)
1503 fput(file);
1504 return retval;
1505}
1506
1507#ifdef __ARCH_WANT_SYS_OLD_MMAP
1508struct mmap_arg_struct {
1509 unsigned long addr;
1510 unsigned long len;
1511 unsigned long prot;
1512 unsigned long flags;
1513 unsigned long fd;
1514 unsigned long offset;
1515};
1516
1517SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1518{
1519 struct mmap_arg_struct a;
1520
1521 if (copy_from_user(&a, arg, sizeof(a)))
1522 return -EFAULT;
1523 if (offset_in_page(a.offset))
1524 return -EINVAL;
1525
1526 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1527 a.offset >> PAGE_SHIFT);
1528}
1529#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1530
1531/*
1532 * Some shared mappigns will want the pages marked read-only
1533 * to track write events. If so, we'll downgrade vm_page_prot
1534 * to the private version (using protection_map[] without the
1535 * VM_SHARED bit).
1536 */
1537int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1538{
1539 vm_flags_t vm_flags = vma->vm_flags;
1540 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1541
1542 /* If it was private or non-writable, the write bit is already clear */
1543 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1544 return 0;
1545
1546 /* The backer wishes to know when pages are first written to? */
1547 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1548 return 1;
1549
1550 /* The open routine did something to the protections that pgprot_modify
1551 * won't preserve? */
1552 if (pgprot_val(vm_page_prot) !=
1553 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1554 return 0;
1555
1556 /* Do we need to track softdirty? */
1557 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1558 return 1;
1559
1560 /* Specialty mapping? */
1561 if (vm_flags & VM_PFNMAP)
1562 return 0;
1563
1564 /* Can the mapping track the dirty pages? */
1565 return vma->vm_file && vma->vm_file->f_mapping &&
1566 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1567}
1568
1569/*
1570 * We account for memory if it's a private writeable mapping,
1571 * not hugepages and VM_NORESERVE wasn't set.
1572 */
1573static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1574{
1575 /*
1576 * hugetlb has its own accounting separate from the core VM
1577 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1578 */
1579 if (file && is_file_hugepages(file))
1580 return 0;
1581
1582 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1583}
1584
1585unsigned long mmap_region(struct file *file, unsigned long addr,
1586 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1587{
1588 struct mm_struct *mm = current->mm;
1589 struct vm_area_struct *vma, *prev;
1590 int error;
1591 struct rb_node **rb_link, *rb_parent;
1592 unsigned long charged = 0;
1593
1594 /* Check against address space limit. */
1595 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1596 unsigned long nr_pages;
1597
1598 /*
1599 * MAP_FIXED may remove pages of mappings that intersects with
1600 * requested mapping. Account for the pages it would unmap.
1601 */
1602 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1603
1604 if (!may_expand_vm(mm, vm_flags,
1605 (len >> PAGE_SHIFT) - nr_pages))
1606 return -ENOMEM;
1607 }
1608
1609 /* Clear old maps */
1610 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1611 &rb_parent)) {
1612 if (do_munmap(mm, addr, len))
1613 return -ENOMEM;
1614 }
1615
1616 /*
1617 * Private writable mapping: check memory availability
1618 */
1619 if (accountable_mapping(file, vm_flags)) {
1620 charged = len >> PAGE_SHIFT;
1621 if (security_vm_enough_memory_mm(mm, charged))
1622 return -ENOMEM;
1623 vm_flags |= VM_ACCOUNT;
1624 }
1625
1626 /*
1627 * Can we just expand an old mapping?
1628 */
1629 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1630 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1631 if (vma)
1632 goto out;
1633
1634 /*
1635 * Determine the object being mapped and call the appropriate
1636 * specific mapper. the address has already been validated, but
1637 * not unmapped, but the maps are removed from the list.
1638 */
1639 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1640 if (!vma) {
1641 error = -ENOMEM;
1642 goto unacct_error;
1643 }
1644
1645 vma->vm_mm = mm;
1646 vma->vm_start = addr;
1647 vma->vm_end = addr + len;
1648 vma->vm_flags = vm_flags;
1649 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1650 vma->vm_pgoff = pgoff;
1651 INIT_LIST_HEAD(&vma->anon_vma_chain);
1652
1653 if (file) {
1654 if (vm_flags & VM_DENYWRITE) {
1655 error = deny_write_access(file);
1656 if (error)
1657 goto free_vma;
1658 }
1659 if (vm_flags & VM_SHARED) {
1660 error = mapping_map_writable(file->f_mapping);
1661 if (error)
1662 goto allow_write_and_free_vma;
1663 }
1664
1665 /* ->mmap() can change vma->vm_file, but must guarantee that
1666 * vma_link() below can deny write-access if VM_DENYWRITE is set
1667 * and map writably if VM_SHARED is set. This usually means the
1668 * new file must not have been exposed to user-space, yet.
1669 */
1670 vma->vm_file = get_file(file);
1671 error = file->f_op->mmap(file, vma);
1672 if (error)
1673 goto unmap_and_free_vma;
1674
1675 /* Can addr have changed??
1676 *
1677 * Answer: Yes, several device drivers can do it in their
1678 * f_op->mmap method. -DaveM
1679 * Bug: If addr is changed, prev, rb_link, rb_parent should
1680 * be updated for vma_link()
1681 */
1682 WARN_ON_ONCE(addr != vma->vm_start);
1683
1684 addr = vma->vm_start;
1685 vm_flags = vma->vm_flags;
1686 } else if (vm_flags & VM_SHARED) {
1687 error = shmem_zero_setup(vma);
1688 if (error)
1689 goto free_vma;
1690 }
1691
1692 vma_link(mm, vma, prev, rb_link, rb_parent);
1693 /* Once vma denies write, undo our temporary denial count */
1694 if (file) {
1695 if (vm_flags & VM_SHARED)
1696 mapping_unmap_writable(file->f_mapping);
1697 if (vm_flags & VM_DENYWRITE)
1698 allow_write_access(file);
1699 }
1700 file = vma->vm_file;
1701out:
1702 perf_event_mmap(vma);
1703
1704 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1705 if (vm_flags & VM_LOCKED) {
1706 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1707 vma == get_gate_vma(current->mm)))
1708 mm->locked_vm += (len >> PAGE_SHIFT);
1709 else
1710 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1711 }
1712
1713 if (file)
1714 uprobe_mmap(vma);
1715
1716 /*
1717 * New (or expanded) vma always get soft dirty status.
1718 * Otherwise user-space soft-dirty page tracker won't
1719 * be able to distinguish situation when vma area unmapped,
1720 * then new mapped in-place (which must be aimed as
1721 * a completely new data area).
1722 */
1723 vma->vm_flags |= VM_SOFTDIRTY;
1724
1725 vma_set_page_prot(vma);
1726
1727 return addr;
1728
1729unmap_and_free_vma:
1730 vma->vm_file = NULL;
1731 fput(file);
1732
1733 /* Undo any partial mapping done by a device driver. */
1734 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1735 charged = 0;
1736 if (vm_flags & VM_SHARED)
1737 mapping_unmap_writable(file->f_mapping);
1738allow_write_and_free_vma:
1739 if (vm_flags & VM_DENYWRITE)
1740 allow_write_access(file);
1741free_vma:
1742 kmem_cache_free(vm_area_cachep, vma);
1743unacct_error:
1744 if (charged)
1745 vm_unacct_memory(charged);
1746 return error;
1747}
1748
1749unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1750{
1751 /*
1752 * We implement the search by looking for an rbtree node that
1753 * immediately follows a suitable gap. That is,
1754 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1755 * - gap_end = vma->vm_start >= info->low_limit + length;
1756 * - gap_end - gap_start >= length
1757 */
1758
1759 struct mm_struct *mm = current->mm;
1760 struct vm_area_struct *vma;
1761 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1762
1763 /* Adjust search length to account for worst case alignment overhead */
1764 length = info->length + info->align_mask;
1765 if (length < info->length)
1766 return -ENOMEM;
1767
1768 /* Adjust search limits by the desired length */
1769 if (info->high_limit < length)
1770 return -ENOMEM;
1771 high_limit = info->high_limit - length;
1772
1773 if (info->low_limit > high_limit)
1774 return -ENOMEM;
1775 low_limit = info->low_limit + length;
1776
1777 /* Check if rbtree root looks promising */
1778 if (RB_EMPTY_ROOT(&mm->mm_rb))
1779 goto check_highest;
1780 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1781 if (vma->rb_subtree_gap < length)
1782 goto check_highest;
1783
1784 while (true) {
1785 /* Visit left subtree if it looks promising */
1786 gap_end = vma->vm_start;
1787 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1788 struct vm_area_struct *left =
1789 rb_entry(vma->vm_rb.rb_left,
1790 struct vm_area_struct, vm_rb);
1791 if (left->rb_subtree_gap >= length) {
1792 vma = left;
1793 continue;
1794 }
1795 }
1796
1797 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1798check_current:
1799 /* Check if current node has a suitable gap */
1800 if (gap_start > high_limit)
1801 return -ENOMEM;
1802 if (gap_end >= low_limit && gap_end - gap_start >= length)
1803 goto found;
1804
1805 /* Visit right subtree if it looks promising */
1806 if (vma->vm_rb.rb_right) {
1807 struct vm_area_struct *right =
1808 rb_entry(vma->vm_rb.rb_right,
1809 struct vm_area_struct, vm_rb);
1810 if (right->rb_subtree_gap >= length) {
1811 vma = right;
1812 continue;
1813 }
1814 }
1815
1816 /* Go back up the rbtree to find next candidate node */
1817 while (true) {
1818 struct rb_node *prev = &vma->vm_rb;
1819 if (!rb_parent(prev))
1820 goto check_highest;
1821 vma = rb_entry(rb_parent(prev),
1822 struct vm_area_struct, vm_rb);
1823 if (prev == vma->vm_rb.rb_left) {
1824 gap_start = vma->vm_prev->vm_end;
1825 gap_end = vma->vm_start;
1826 goto check_current;
1827 }
1828 }
1829 }
1830
1831check_highest:
1832 /* Check highest gap, which does not precede any rbtree node */
1833 gap_start = mm->highest_vm_end;
1834 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1835 if (gap_start > high_limit)
1836 return -ENOMEM;
1837
1838found:
1839 /* We found a suitable gap. Clip it with the original low_limit. */
1840 if (gap_start < info->low_limit)
1841 gap_start = info->low_limit;
1842
1843 /* Adjust gap address to the desired alignment */
1844 gap_start += (info->align_offset - gap_start) & info->align_mask;
1845
1846 VM_BUG_ON(gap_start + info->length > info->high_limit);
1847 VM_BUG_ON(gap_start + info->length > gap_end);
1848 return gap_start;
1849}
1850
1851unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1852{
1853 struct mm_struct *mm = current->mm;
1854 struct vm_area_struct *vma;
1855 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1856
1857 /* Adjust search length to account for worst case alignment overhead */
1858 length = info->length + info->align_mask;
1859 if (length < info->length)
1860 return -ENOMEM;
1861
1862 /*
1863 * Adjust search limits by the desired length.
1864 * See implementation comment at top of unmapped_area().
1865 */
1866 gap_end = info->high_limit;
1867 if (gap_end < length)
1868 return -ENOMEM;
1869 high_limit = gap_end - length;
1870
1871 if (info->low_limit > high_limit)
1872 return -ENOMEM;
1873 low_limit = info->low_limit + length;
1874
1875 /* Check highest gap, which does not precede any rbtree node */
1876 gap_start = mm->highest_vm_end;
1877 if (gap_start <= high_limit)
1878 goto found_highest;
1879
1880 /* Check if rbtree root looks promising */
1881 if (RB_EMPTY_ROOT(&mm->mm_rb))
1882 return -ENOMEM;
1883 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1884 if (vma->rb_subtree_gap < length)
1885 return -ENOMEM;
1886
1887 while (true) {
1888 /* Visit right subtree if it looks promising */
1889 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1890 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1891 struct vm_area_struct *right =
1892 rb_entry(vma->vm_rb.rb_right,
1893 struct vm_area_struct, vm_rb);
1894 if (right->rb_subtree_gap >= length) {
1895 vma = right;
1896 continue;
1897 }
1898 }
1899
1900check_current:
1901 /* Check if current node has a suitable gap */
1902 gap_end = vma->vm_start;
1903 if (gap_end < low_limit)
1904 return -ENOMEM;
1905 if (gap_start <= high_limit && gap_end - gap_start >= length)
1906 goto found;
1907
1908 /* Visit left subtree if it looks promising */
1909 if (vma->vm_rb.rb_left) {
1910 struct vm_area_struct *left =
1911 rb_entry(vma->vm_rb.rb_left,
1912 struct vm_area_struct, vm_rb);
1913 if (left->rb_subtree_gap >= length) {
1914 vma = left;
1915 continue;
1916 }
1917 }
1918
1919 /* Go back up the rbtree to find next candidate node */
1920 while (true) {
1921 struct rb_node *prev = &vma->vm_rb;
1922 if (!rb_parent(prev))
1923 return -ENOMEM;
1924 vma = rb_entry(rb_parent(prev),
1925 struct vm_area_struct, vm_rb);
1926 if (prev == vma->vm_rb.rb_right) {
1927 gap_start = vma->vm_prev ?
1928 vma->vm_prev->vm_end : 0;
1929 goto check_current;
1930 }
1931 }
1932 }
1933
1934found:
1935 /* We found a suitable gap. Clip it with the original high_limit. */
1936 if (gap_end > info->high_limit)
1937 gap_end = info->high_limit;
1938
1939found_highest:
1940 /* Compute highest gap address at the desired alignment */
1941 gap_end -= info->length;
1942 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1943
1944 VM_BUG_ON(gap_end < info->low_limit);
1945 VM_BUG_ON(gap_end < gap_start);
1946 return gap_end;
1947}
1948
1949/* Get an address range which is currently unmapped.
1950 * For shmat() with addr=0.
1951 *
1952 * Ugly calling convention alert:
1953 * Return value with the low bits set means error value,
1954 * ie
1955 * if (ret & ~PAGE_MASK)
1956 * error = ret;
1957 *
1958 * This function "knows" that -ENOMEM has the bits set.
1959 */
1960#ifndef HAVE_ARCH_UNMAPPED_AREA
1961unsigned long
1962arch_get_unmapped_area(struct file *filp, unsigned long addr,
1963 unsigned long len, unsigned long pgoff, unsigned long flags)
1964{
1965 struct mm_struct *mm = current->mm;
1966 struct vm_area_struct *vma;
1967 struct vm_unmapped_area_info info;
1968
1969 if (len > TASK_SIZE - mmap_min_addr)
1970 return -ENOMEM;
1971
1972 if (flags & MAP_FIXED)
1973 return addr;
1974
1975 if (addr) {
1976 addr = PAGE_ALIGN(addr);
1977 vma = find_vma(mm, addr);
1978 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1979 (!vma || addr + len <= vma->vm_start))
1980 return addr;
1981 }
1982
1983 info.flags = 0;
1984 info.length = len;
1985 info.low_limit = mm->mmap_base;
1986 info.high_limit = TASK_SIZE;
1987 info.align_mask = 0;
1988 return vm_unmapped_area(&info);
1989}
1990#endif
1991
1992/*
1993 * This mmap-allocator allocates new areas top-down from below the
1994 * stack's low limit (the base):
1995 */
1996#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1997unsigned long
1998arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1999 const unsigned long len, const unsigned long pgoff,
2000 const unsigned long flags)
2001{
2002 struct vm_area_struct *vma;
2003 struct mm_struct *mm = current->mm;
2004 unsigned long addr = addr0;
2005 struct vm_unmapped_area_info info;
2006
2007 /* requested length too big for entire address space */
2008 if (len > TASK_SIZE - mmap_min_addr)
2009 return -ENOMEM;
2010
2011 if (flags & MAP_FIXED)
2012 return addr;
2013
2014 /* requesting a specific address */
2015 if (addr) {
2016 addr = PAGE_ALIGN(addr);
2017 vma = find_vma(mm, addr);
2018 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
2019 (!vma || addr + len <= vma->vm_start))
2020 return addr;
2021 }
2022
2023 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2024 info.length = len;
2025 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2026 info.high_limit = mm->mmap_base;
2027 info.align_mask = 0;
2028 addr = vm_unmapped_area(&info);
2029
2030 /*
2031 * A failed mmap() very likely causes application failure,
2032 * so fall back to the bottom-up function here. This scenario
2033 * can happen with large stack limits and large mmap()
2034 * allocations.
2035 */
2036 if (offset_in_page(addr)) {
2037 VM_BUG_ON(addr != -ENOMEM);
2038 info.flags = 0;
2039 info.low_limit = TASK_UNMAPPED_BASE;
2040 info.high_limit = TASK_SIZE;
2041 addr = vm_unmapped_area(&info);
2042 }
2043
2044 return addr;
2045}
2046#endif
2047
2048unsigned long
2049get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2050 unsigned long pgoff, unsigned long flags)
2051{
2052 unsigned long (*get_area)(struct file *, unsigned long,
2053 unsigned long, unsigned long, unsigned long);
2054
2055 unsigned long error = arch_mmap_check(addr, len, flags);
2056 if (error)
2057 return error;
2058
2059 /* Careful about overflows.. */
2060 if (len > TASK_SIZE)
2061 return -ENOMEM;
2062
2063 get_area = current->mm->get_unmapped_area;
2064 if (file) {
2065 if (file->f_op->get_unmapped_area)
2066 get_area = file->f_op->get_unmapped_area;
2067 } else if (flags & MAP_SHARED) {
2068 /*
2069 * mmap_region() will call shmem_zero_setup() to create a file,
2070 * so use shmem's get_unmapped_area in case it can be huge.
2071 * do_mmap_pgoff() will clear pgoff, so match alignment.
2072 */
2073 pgoff = 0;
2074 get_area = shmem_get_unmapped_area;
2075 }
2076
2077 addr = get_area(file, addr, len, pgoff, flags);
2078 if (IS_ERR_VALUE(addr))
2079 return addr;
2080
2081 if (addr > TASK_SIZE - len)
2082 return -ENOMEM;
2083 if (offset_in_page(addr))
2084 return -EINVAL;
2085
2086 error = security_mmap_addr(addr);
2087 return error ? error : addr;
2088}
2089
2090EXPORT_SYMBOL(get_unmapped_area);
2091
2092/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2093struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2094{
2095 struct rb_node *rb_node;
2096 struct vm_area_struct *vma;
2097
2098 /* Check the cache first. */
2099 vma = vmacache_find(mm, addr);
2100 if (likely(vma))
2101 return vma;
2102
2103 rb_node = mm->mm_rb.rb_node;
2104
2105 while (rb_node) {
2106 struct vm_area_struct *tmp;
2107
2108 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2109
2110 if (tmp->vm_end > addr) {
2111 vma = tmp;
2112 if (tmp->vm_start <= addr)
2113 break;
2114 rb_node = rb_node->rb_left;
2115 } else
2116 rb_node = rb_node->rb_right;
2117 }
2118
2119 if (vma)
2120 vmacache_update(addr, vma);
2121 return vma;
2122}
2123
2124EXPORT_SYMBOL(find_vma);
2125
2126/*
2127 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2128 */
2129struct vm_area_struct *
2130find_vma_prev(struct mm_struct *mm, unsigned long addr,
2131 struct vm_area_struct **pprev)
2132{
2133 struct vm_area_struct *vma;
2134
2135 vma = find_vma(mm, addr);
2136 if (vma) {
2137 *pprev = vma->vm_prev;
2138 } else {
2139 struct rb_node *rb_node = mm->mm_rb.rb_node;
2140 *pprev = NULL;
2141 while (rb_node) {
2142 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2143 rb_node = rb_node->rb_right;
2144 }
2145 }
2146 return vma;
2147}
2148
2149/*
2150 * Verify that the stack growth is acceptable and
2151 * update accounting. This is shared with both the
2152 * grow-up and grow-down cases.
2153 */
2154static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2155{
2156 struct mm_struct *mm = vma->vm_mm;
2157 struct rlimit *rlim = current->signal->rlim;
2158 unsigned long new_start, actual_size;
2159
2160 /* address space limit tests */
2161 if (!may_expand_vm(mm, vma->vm_flags, grow))
2162 return -ENOMEM;
2163
2164 /* Stack limit test */
2165 actual_size = size;
2166 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2167 actual_size -= PAGE_SIZE;
2168 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2169 return -ENOMEM;
2170
2171 /* mlock limit tests */
2172 if (vma->vm_flags & VM_LOCKED) {
2173 unsigned long locked;
2174 unsigned long limit;
2175 locked = mm->locked_vm + grow;
2176 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2177 limit >>= PAGE_SHIFT;
2178 if (locked > limit && !capable(CAP_IPC_LOCK))
2179 return -ENOMEM;
2180 }
2181
2182 /* Check to ensure the stack will not grow into a hugetlb-only region */
2183 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2184 vma->vm_end - size;
2185 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2186 return -EFAULT;
2187
2188 /*
2189 * Overcommit.. This must be the final test, as it will
2190 * update security statistics.
2191 */
2192 if (security_vm_enough_memory_mm(mm, grow))
2193 return -ENOMEM;
2194
2195 return 0;
2196}
2197
2198#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2199/*
2200 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2201 * vma is the last one with address > vma->vm_end. Have to extend vma.
2202 */
2203int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2204{
2205 struct mm_struct *mm = vma->vm_mm;
2206 int error = 0;
2207
2208 if (!(vma->vm_flags & VM_GROWSUP))
2209 return -EFAULT;
2210
2211 /* Guard against wrapping around to address 0. */
2212 if (address < PAGE_ALIGN(address+4))
2213 address = PAGE_ALIGN(address+4);
2214 else
2215 return -ENOMEM;
2216
2217 /* We must make sure the anon_vma is allocated. */
2218 if (unlikely(anon_vma_prepare(vma)))
2219 return -ENOMEM;
2220
2221 /*
2222 * vma->vm_start/vm_end cannot change under us because the caller
2223 * is required to hold the mmap_sem in read mode. We need the
2224 * anon_vma lock to serialize against concurrent expand_stacks.
2225 */
2226 anon_vma_lock_write(vma->anon_vma);
2227
2228 /* Somebody else might have raced and expanded it already */
2229 if (address > vma->vm_end) {
2230 unsigned long size, grow;
2231
2232 size = address - vma->vm_start;
2233 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2234
2235 error = -ENOMEM;
2236 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2237 error = acct_stack_growth(vma, size, grow);
2238 if (!error) {
2239 /*
2240 * vma_gap_update() doesn't support concurrent
2241 * updates, but we only hold a shared mmap_sem
2242 * lock here, so we need to protect against
2243 * concurrent vma expansions.
2244 * anon_vma_lock_write() doesn't help here, as
2245 * we don't guarantee that all growable vmas
2246 * in a mm share the same root anon vma.
2247 * So, we reuse mm->page_table_lock to guard
2248 * against concurrent vma expansions.
2249 */
2250 spin_lock(&mm->page_table_lock);
2251 if (vma->vm_flags & VM_LOCKED)
2252 mm->locked_vm += grow;
2253 vm_stat_account(mm, vma->vm_flags, grow);
2254 anon_vma_interval_tree_pre_update_vma(vma);
2255 vma->vm_end = address;
2256 anon_vma_interval_tree_post_update_vma(vma);
2257 if (vma->vm_next)
2258 vma_gap_update(vma->vm_next);
2259 else
2260 mm->highest_vm_end = address;
2261 spin_unlock(&mm->page_table_lock);
2262
2263 perf_event_mmap(vma);
2264 }
2265 }
2266 }
2267 anon_vma_unlock_write(vma->anon_vma);
2268 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2269 validate_mm(mm);
2270 return error;
2271}
2272#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2273
2274/*
2275 * vma is the first one with address < vma->vm_start. Have to extend vma.
2276 */
2277int expand_downwards(struct vm_area_struct *vma,
2278 unsigned long address)
2279{
2280 struct mm_struct *mm = vma->vm_mm;
2281 int error;
2282
2283 address &= PAGE_MASK;
2284 error = security_mmap_addr(address);
2285 if (error)
2286 return error;
2287
2288 /* We must make sure the anon_vma is allocated. */
2289 if (unlikely(anon_vma_prepare(vma)))
2290 return -ENOMEM;
2291
2292 /*
2293 * vma->vm_start/vm_end cannot change under us because the caller
2294 * is required to hold the mmap_sem in read mode. We need the
2295 * anon_vma lock to serialize against concurrent expand_stacks.
2296 */
2297 anon_vma_lock_write(vma->anon_vma);
2298
2299 /* Somebody else might have raced and expanded it already */
2300 if (address < vma->vm_start) {
2301 unsigned long size, grow;
2302
2303 size = vma->vm_end - address;
2304 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2305
2306 error = -ENOMEM;
2307 if (grow <= vma->vm_pgoff) {
2308 error = acct_stack_growth(vma, size, grow);
2309 if (!error) {
2310 /*
2311 * vma_gap_update() doesn't support concurrent
2312 * updates, but we only hold a shared mmap_sem
2313 * lock here, so we need to protect against
2314 * concurrent vma expansions.
2315 * anon_vma_lock_write() doesn't help here, as
2316 * we don't guarantee that all growable vmas
2317 * in a mm share the same root anon vma.
2318 * So, we reuse mm->page_table_lock to guard
2319 * against concurrent vma expansions.
2320 */
2321 spin_lock(&mm->page_table_lock);
2322 if (vma->vm_flags & VM_LOCKED)
2323 mm->locked_vm += grow;
2324 vm_stat_account(mm, vma->vm_flags, grow);
2325 anon_vma_interval_tree_pre_update_vma(vma);
2326 vma->vm_start = address;
2327 vma->vm_pgoff -= grow;
2328 anon_vma_interval_tree_post_update_vma(vma);
2329 vma_gap_update(vma);
2330 spin_unlock(&mm->page_table_lock);
2331
2332 perf_event_mmap(vma);
2333 }
2334 }
2335 }
2336 anon_vma_unlock_write(vma->anon_vma);
2337 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2338 validate_mm(mm);
2339 return error;
2340}
2341
2342/*
2343 * Note how expand_stack() refuses to expand the stack all the way to
2344 * abut the next virtual mapping, *unless* that mapping itself is also
2345 * a stack mapping. We want to leave room for a guard page, after all
2346 * (the guard page itself is not added here, that is done by the
2347 * actual page faulting logic)
2348 *
2349 * This matches the behavior of the guard page logic (see mm/memory.c:
2350 * check_stack_guard_page()), which only allows the guard page to be
2351 * removed under these circumstances.
2352 */
2353#ifdef CONFIG_STACK_GROWSUP
2354int expand_stack(struct vm_area_struct *vma, unsigned long address)
2355{
2356 struct vm_area_struct *next;
2357
2358 address &= PAGE_MASK;
2359 next = vma->vm_next;
2360 if (next && next->vm_start == address + PAGE_SIZE) {
2361 if (!(next->vm_flags & VM_GROWSUP))
2362 return -ENOMEM;
2363 }
2364 return expand_upwards(vma, address);
2365}
2366
2367struct vm_area_struct *
2368find_extend_vma(struct mm_struct *mm, unsigned long addr)
2369{
2370 struct vm_area_struct *vma, *prev;
2371
2372 addr &= PAGE_MASK;
2373 vma = find_vma_prev(mm, addr, &prev);
2374 if (vma && (vma->vm_start <= addr))
2375 return vma;
2376 if (!prev || expand_stack(prev, addr))
2377 return NULL;
2378 if (prev->vm_flags & VM_LOCKED)
2379 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2380 return prev;
2381}
2382#else
2383int expand_stack(struct vm_area_struct *vma, unsigned long address)
2384{
2385 struct vm_area_struct *prev;
2386
2387 address &= PAGE_MASK;
2388 prev = vma->vm_prev;
2389 if (prev && prev->vm_end == address) {
2390 if (!(prev->vm_flags & VM_GROWSDOWN))
2391 return -ENOMEM;
2392 }
2393 return expand_downwards(vma, address);
2394}
2395
2396struct vm_area_struct *
2397find_extend_vma(struct mm_struct *mm, unsigned long addr)
2398{
2399 struct vm_area_struct *vma;
2400 unsigned long start;
2401
2402 addr &= PAGE_MASK;
2403 vma = find_vma(mm, addr);
2404 if (!vma)
2405 return NULL;
2406 if (vma->vm_start <= addr)
2407 return vma;
2408 if (!(vma->vm_flags & VM_GROWSDOWN))
2409 return NULL;
2410 start = vma->vm_start;
2411 if (expand_stack(vma, addr))
2412 return NULL;
2413 if (vma->vm_flags & VM_LOCKED)
2414 populate_vma_page_range(vma, addr, start, NULL);
2415 return vma;
2416}
2417#endif
2418
2419EXPORT_SYMBOL_GPL(find_extend_vma);
2420
2421/*
2422 * Ok - we have the memory areas we should free on the vma list,
2423 * so release them, and do the vma updates.
2424 *
2425 * Called with the mm semaphore held.
2426 */
2427static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2428{
2429 unsigned long nr_accounted = 0;
2430
2431 /* Update high watermark before we lower total_vm */
2432 update_hiwater_vm(mm);
2433 do {
2434 long nrpages = vma_pages(vma);
2435
2436 if (vma->vm_flags & VM_ACCOUNT)
2437 nr_accounted += nrpages;
2438 vm_stat_account(mm, vma->vm_flags, -nrpages);
2439 vma = remove_vma(vma);
2440 } while (vma);
2441 vm_unacct_memory(nr_accounted);
2442 validate_mm(mm);
2443}
2444
2445/*
2446 * Get rid of page table information in the indicated region.
2447 *
2448 * Called with the mm semaphore held.
2449 */
2450static void unmap_region(struct mm_struct *mm,
2451 struct vm_area_struct *vma, struct vm_area_struct *prev,
2452 unsigned long start, unsigned long end)
2453{
2454 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2455 struct mmu_gather tlb;
2456
2457 lru_add_drain();
2458 tlb_gather_mmu(&tlb, mm, start, end);
2459 update_hiwater_rss(mm);
2460 unmap_vmas(&tlb, vma, start, end);
2461 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2462 next ? next->vm_start : USER_PGTABLES_CEILING);
2463 tlb_finish_mmu(&tlb, start, end);
2464}
2465
2466/*
2467 * Create a list of vma's touched by the unmap, removing them from the mm's
2468 * vma list as we go..
2469 */
2470static void
2471detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2472 struct vm_area_struct *prev, unsigned long end)
2473{
2474 struct vm_area_struct **insertion_point;
2475 struct vm_area_struct *tail_vma = NULL;
2476
2477 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2478 vma->vm_prev = NULL;
2479 do {
2480 vma_rb_erase(vma, &mm->mm_rb);
2481 mm->map_count--;
2482 tail_vma = vma;
2483 vma = vma->vm_next;
2484 } while (vma && vma->vm_start < end);
2485 *insertion_point = vma;
2486 if (vma) {
2487 vma->vm_prev = prev;
2488 vma_gap_update(vma);
2489 } else
2490 mm->highest_vm_end = prev ? prev->vm_end : 0;
2491 tail_vma->vm_next = NULL;
2492
2493 /* Kill the cache */
2494 vmacache_invalidate(mm);
2495}
2496
2497/*
2498 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2499 * munmap path where it doesn't make sense to fail.
2500 */
2501static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2502 unsigned long addr, int new_below)
2503{
2504 struct vm_area_struct *new;
2505 int err;
2506
2507 if (is_vm_hugetlb_page(vma) && (addr &
2508 ~(huge_page_mask(hstate_vma(vma)))))
2509 return -EINVAL;
2510
2511 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2512 if (!new)
2513 return -ENOMEM;
2514
2515 /* most fields are the same, copy all, and then fixup */
2516 *new = *vma;
2517
2518 INIT_LIST_HEAD(&new->anon_vma_chain);
2519
2520 if (new_below)
2521 new->vm_end = addr;
2522 else {
2523 new->vm_start = addr;
2524 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2525 }
2526
2527 err = vma_dup_policy(vma, new);
2528 if (err)
2529 goto out_free_vma;
2530
2531 err = anon_vma_clone(new, vma);
2532 if (err)
2533 goto out_free_mpol;
2534
2535 if (new->vm_file)
2536 get_file(new->vm_file);
2537
2538 if (new->vm_ops && new->vm_ops->open)
2539 new->vm_ops->open(new);
2540
2541 if (new_below)
2542 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2543 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2544 else
2545 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2546
2547 /* Success. */
2548 if (!err)
2549 return 0;
2550
2551 /* Clean everything up if vma_adjust failed. */
2552 if (new->vm_ops && new->vm_ops->close)
2553 new->vm_ops->close(new);
2554 if (new->vm_file)
2555 fput(new->vm_file);
2556 unlink_anon_vmas(new);
2557 out_free_mpol:
2558 mpol_put(vma_policy(new));
2559 out_free_vma:
2560 kmem_cache_free(vm_area_cachep, new);
2561 return err;
2562}
2563
2564/*
2565 * Split a vma into two pieces at address 'addr', a new vma is allocated
2566 * either for the first part or the tail.
2567 */
2568int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2569 unsigned long addr, int new_below)
2570{
2571 if (mm->map_count >= sysctl_max_map_count)
2572 return -ENOMEM;
2573
2574 return __split_vma(mm, vma, addr, new_below);
2575}
2576
2577/* Munmap is split into 2 main parts -- this part which finds
2578 * what needs doing, and the areas themselves, which do the
2579 * work. This now handles partial unmappings.
2580 * Jeremy Fitzhardinge <jeremy@goop.org>
2581 */
2582int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2583{
2584 unsigned long end;
2585 struct vm_area_struct *vma, *prev, *last;
2586
2587 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2588 return -EINVAL;
2589
2590 len = PAGE_ALIGN(len);
2591 if (len == 0)
2592 return -EINVAL;
2593
2594 /* Find the first overlapping VMA */
2595 vma = find_vma(mm, start);
2596 if (!vma)
2597 return 0;
2598 prev = vma->vm_prev;
2599 /* we have start < vma->vm_end */
2600
2601 /* if it doesn't overlap, we have nothing.. */
2602 end = start + len;
2603 if (vma->vm_start >= end)
2604 return 0;
2605
2606 /*
2607 * If we need to split any vma, do it now to save pain later.
2608 *
2609 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2610 * unmapped vm_area_struct will remain in use: so lower split_vma
2611 * places tmp vma above, and higher split_vma places tmp vma below.
2612 */
2613 if (start > vma->vm_start) {
2614 int error;
2615
2616 /*
2617 * Make sure that map_count on return from munmap() will
2618 * not exceed its limit; but let map_count go just above
2619 * its limit temporarily, to help free resources as expected.
2620 */
2621 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2622 return -ENOMEM;
2623
2624 error = __split_vma(mm, vma, start, 0);
2625 if (error)
2626 return error;
2627 prev = vma;
2628 }
2629
2630 /* Does it split the last one? */
2631 last = find_vma(mm, end);
2632 if (last && end > last->vm_start) {
2633 int error = __split_vma(mm, last, end, 1);
2634 if (error)
2635 return error;
2636 }
2637 vma = prev ? prev->vm_next : mm->mmap;
2638
2639 /*
2640 * unlock any mlock()ed ranges before detaching vmas
2641 */
2642 if (mm->locked_vm) {
2643 struct vm_area_struct *tmp = vma;
2644 while (tmp && tmp->vm_start < end) {
2645 if (tmp->vm_flags & VM_LOCKED) {
2646 mm->locked_vm -= vma_pages(tmp);
2647 munlock_vma_pages_all(tmp);
2648 }
2649 tmp = tmp->vm_next;
2650 }
2651 }
2652
2653 /*
2654 * Remove the vma's, and unmap the actual pages
2655 */
2656 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2657 unmap_region(mm, vma, prev, start, end);
2658
2659 arch_unmap(mm, vma, start, end);
2660
2661 /* Fix up all other VM information */
2662 remove_vma_list(mm, vma);
2663
2664 return 0;
2665}
2666
2667int vm_munmap(unsigned long start, size_t len)
2668{
2669 int ret;
2670 struct mm_struct *mm = current->mm;
2671
2672 if (down_write_killable(&mm->mmap_sem))
2673 return -EINTR;
2674
2675 ret = do_munmap(mm, start, len);
2676 up_write(&mm->mmap_sem);
2677 return ret;
2678}
2679EXPORT_SYMBOL(vm_munmap);
2680
2681SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2682{
2683 int ret;
2684 struct mm_struct *mm = current->mm;
2685
2686 profile_munmap(addr);
2687 if (down_write_killable(&mm->mmap_sem))
2688 return -EINTR;
2689 ret = do_munmap(mm, addr, len);
2690 up_write(&mm->mmap_sem);
2691 return ret;
2692}
2693
2694
2695/*
2696 * Emulation of deprecated remap_file_pages() syscall.
2697 */
2698SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2699 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2700{
2701
2702 struct mm_struct *mm = current->mm;
2703 struct vm_area_struct *vma;
2704 unsigned long populate = 0;
2705 unsigned long ret = -EINVAL;
2706 struct file *file;
2707
2708 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2709 current->comm, current->pid);
2710
2711 if (prot)
2712 return ret;
2713 start = start & PAGE_MASK;
2714 size = size & PAGE_MASK;
2715
2716 if (start + size <= start)
2717 return ret;
2718
2719 /* Does pgoff wrap? */
2720 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2721 return ret;
2722
2723 if (down_write_killable(&mm->mmap_sem))
2724 return -EINTR;
2725
2726 vma = find_vma(mm, start);
2727
2728 if (!vma || !(vma->vm_flags & VM_SHARED))
2729 goto out;
2730
2731 if (start < vma->vm_start)
2732 goto out;
2733
2734 if (start + size > vma->vm_end) {
2735 struct vm_area_struct *next;
2736
2737 for (next = vma->vm_next; next; next = next->vm_next) {
2738 /* hole between vmas ? */
2739 if (next->vm_start != next->vm_prev->vm_end)
2740 goto out;
2741
2742 if (next->vm_file != vma->vm_file)
2743 goto out;
2744
2745 if (next->vm_flags != vma->vm_flags)
2746 goto out;
2747
2748 if (start + size <= next->vm_end)
2749 break;
2750 }
2751
2752 if (!next)
2753 goto out;
2754 }
2755
2756 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2757 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2758 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2759
2760 flags &= MAP_NONBLOCK;
2761 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2762 if (vma->vm_flags & VM_LOCKED) {
2763 struct vm_area_struct *tmp;
2764 flags |= MAP_LOCKED;
2765
2766 /* drop PG_Mlocked flag for over-mapped range */
2767 for (tmp = vma; tmp->vm_start >= start + size;
2768 tmp = tmp->vm_next) {
2769 /*
2770 * Split pmd and munlock page on the border
2771 * of the range.
2772 */
2773 vma_adjust_trans_huge(tmp, start, start + size, 0);
2774
2775 munlock_vma_pages_range(tmp,
2776 max(tmp->vm_start, start),
2777 min(tmp->vm_end, start + size));
2778 }
2779 }
2780
2781 file = get_file(vma->vm_file);
2782 ret = do_mmap_pgoff(vma->vm_file, start, size,
2783 prot, flags, pgoff, &populate);
2784 fput(file);
2785out:
2786 up_write(&mm->mmap_sem);
2787 if (populate)
2788 mm_populate(ret, populate);
2789 if (!IS_ERR_VALUE(ret))
2790 ret = 0;
2791 return ret;
2792}
2793
2794static inline void verify_mm_writelocked(struct mm_struct *mm)
2795{
2796#ifdef CONFIG_DEBUG_VM
2797 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2798 WARN_ON(1);
2799 up_read(&mm->mmap_sem);
2800 }
2801#endif
2802}
2803
2804/*
2805 * this is really a simplified "do_mmap". it only handles
2806 * anonymous maps. eventually we may be able to do some
2807 * brk-specific accounting here.
2808 */
2809static int do_brk(unsigned long addr, unsigned long request)
2810{
2811 struct mm_struct *mm = current->mm;
2812 struct vm_area_struct *vma, *prev;
2813 unsigned long flags, len;
2814 struct rb_node **rb_link, *rb_parent;
2815 pgoff_t pgoff = addr >> PAGE_SHIFT;
2816 int error;
2817
2818 len = PAGE_ALIGN(request);
2819 if (len < request)
2820 return -ENOMEM;
2821 if (!len)
2822 return 0;
2823
2824 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2825
2826 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2827 if (offset_in_page(error))
2828 return error;
2829
2830 error = mlock_future_check(mm, mm->def_flags, len);
2831 if (error)
2832 return error;
2833
2834 /*
2835 * mm->mmap_sem is required to protect against another thread
2836 * changing the mappings in case we sleep.
2837 */
2838 verify_mm_writelocked(mm);
2839
2840 /*
2841 * Clear old maps. this also does some error checking for us
2842 */
2843 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2844 &rb_parent)) {
2845 if (do_munmap(mm, addr, len))
2846 return -ENOMEM;
2847 }
2848
2849 /* Check against address space limits *after* clearing old maps... */
2850 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2851 return -ENOMEM;
2852
2853 if (mm->map_count > sysctl_max_map_count)
2854 return -ENOMEM;
2855
2856 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2857 return -ENOMEM;
2858
2859 /* Can we just expand an old private anonymous mapping? */
2860 vma = vma_merge(mm, prev, addr, addr + len, flags,
2861 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2862 if (vma)
2863 goto out;
2864
2865 /*
2866 * create a vma struct for an anonymous mapping
2867 */
2868 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2869 if (!vma) {
2870 vm_unacct_memory(len >> PAGE_SHIFT);
2871 return -ENOMEM;
2872 }
2873
2874 INIT_LIST_HEAD(&vma->anon_vma_chain);
2875 vma->vm_mm = mm;
2876 vma->vm_start = addr;
2877 vma->vm_end = addr + len;
2878 vma->vm_pgoff = pgoff;
2879 vma->vm_flags = flags;
2880 vma->vm_page_prot = vm_get_page_prot(flags);
2881 vma_link(mm, vma, prev, rb_link, rb_parent);
2882out:
2883 perf_event_mmap(vma);
2884 mm->total_vm += len >> PAGE_SHIFT;
2885 mm->data_vm += len >> PAGE_SHIFT;
2886 if (flags & VM_LOCKED)
2887 mm->locked_vm += (len >> PAGE_SHIFT);
2888 vma->vm_flags |= VM_SOFTDIRTY;
2889 return 0;
2890}
2891
2892int vm_brk(unsigned long addr, unsigned long len)
2893{
2894 struct mm_struct *mm = current->mm;
2895 int ret;
2896 bool populate;
2897
2898 if (down_write_killable(&mm->mmap_sem))
2899 return -EINTR;
2900
2901 ret = do_brk(addr, len);
2902 populate = ((mm->def_flags & VM_LOCKED) != 0);
2903 up_write(&mm->mmap_sem);
2904 if (populate && !ret)
2905 mm_populate(addr, len);
2906 return ret;
2907}
2908EXPORT_SYMBOL(vm_brk);
2909
2910/* Release all mmaps. */
2911void exit_mmap(struct mm_struct *mm)
2912{
2913 struct mmu_gather tlb;
2914 struct vm_area_struct *vma;
2915 unsigned long nr_accounted = 0;
2916
2917 /* mm's last user has gone, and its about to be pulled down */
2918 mmu_notifier_release(mm);
2919
2920 if (mm->locked_vm) {
2921 vma = mm->mmap;
2922 while (vma) {
2923 if (vma->vm_flags & VM_LOCKED)
2924 munlock_vma_pages_all(vma);
2925 vma = vma->vm_next;
2926 }
2927 }
2928
2929 arch_exit_mmap(mm);
2930
2931 vma = mm->mmap;
2932 if (!vma) /* Can happen if dup_mmap() received an OOM */
2933 return;
2934
2935 lru_add_drain();
2936 flush_cache_mm(mm);
2937 tlb_gather_mmu(&tlb, mm, 0, -1);
2938 /* update_hiwater_rss(mm) here? but nobody should be looking */
2939 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2940 unmap_vmas(&tlb, vma, 0, -1);
2941
2942 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2943 tlb_finish_mmu(&tlb, 0, -1);
2944
2945 /*
2946 * Walk the list again, actually closing and freeing it,
2947 * with preemption enabled, without holding any MM locks.
2948 */
2949 while (vma) {
2950 if (vma->vm_flags & VM_ACCOUNT)
2951 nr_accounted += vma_pages(vma);
2952 vma = remove_vma(vma);
2953 }
2954 vm_unacct_memory(nr_accounted);
2955}
2956
2957/* Insert vm structure into process list sorted by address
2958 * and into the inode's i_mmap tree. If vm_file is non-NULL
2959 * then i_mmap_rwsem is taken here.
2960 */
2961int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2962{
2963 struct vm_area_struct *prev;
2964 struct rb_node **rb_link, *rb_parent;
2965
2966 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2967 &prev, &rb_link, &rb_parent))
2968 return -ENOMEM;
2969 if ((vma->vm_flags & VM_ACCOUNT) &&
2970 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2971 return -ENOMEM;
2972
2973 /*
2974 * The vm_pgoff of a purely anonymous vma should be irrelevant
2975 * until its first write fault, when page's anon_vma and index
2976 * are set. But now set the vm_pgoff it will almost certainly
2977 * end up with (unless mremap moves it elsewhere before that
2978 * first wfault), so /proc/pid/maps tells a consistent story.
2979 *
2980 * By setting it to reflect the virtual start address of the
2981 * vma, merges and splits can happen in a seamless way, just
2982 * using the existing file pgoff checks and manipulations.
2983 * Similarly in do_mmap_pgoff and in do_brk.
2984 */
2985 if (vma_is_anonymous(vma)) {
2986 BUG_ON(vma->anon_vma);
2987 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2988 }
2989
2990 vma_link(mm, vma, prev, rb_link, rb_parent);
2991 return 0;
2992}
2993
2994/*
2995 * Copy the vma structure to a new location in the same mm,
2996 * prior to moving page table entries, to effect an mremap move.
2997 */
2998struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2999 unsigned long addr, unsigned long len, pgoff_t pgoff,
3000 bool *need_rmap_locks)
3001{
3002 struct vm_area_struct *vma = *vmap;
3003 unsigned long vma_start = vma->vm_start;
3004 struct mm_struct *mm = vma->vm_mm;
3005 struct vm_area_struct *new_vma, *prev;
3006 struct rb_node **rb_link, *rb_parent;
3007 bool faulted_in_anon_vma = true;
3008
3009 /*
3010 * If anonymous vma has not yet been faulted, update new pgoff
3011 * to match new location, to increase its chance of merging.
3012 */
3013 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3014 pgoff = addr >> PAGE_SHIFT;
3015 faulted_in_anon_vma = false;
3016 }
3017
3018 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3019 return NULL; /* should never get here */
3020 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3021 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3022 vma->vm_userfaultfd_ctx);
3023 if (new_vma) {
3024 /*
3025 * Source vma may have been merged into new_vma
3026 */
3027 if (unlikely(vma_start >= new_vma->vm_start &&
3028 vma_start < new_vma->vm_end)) {
3029 /*
3030 * The only way we can get a vma_merge with
3031 * self during an mremap is if the vma hasn't
3032 * been faulted in yet and we were allowed to
3033 * reset the dst vma->vm_pgoff to the
3034 * destination address of the mremap to allow
3035 * the merge to happen. mremap must change the
3036 * vm_pgoff linearity between src and dst vmas
3037 * (in turn preventing a vma_merge) to be
3038 * safe. It is only safe to keep the vm_pgoff
3039 * linear if there are no pages mapped yet.
3040 */
3041 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3042 *vmap = vma = new_vma;
3043 }
3044 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3045 } else {
3046 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
3047 if (!new_vma)
3048 goto out;
3049 *new_vma = *vma;
3050 new_vma->vm_start = addr;
3051 new_vma->vm_end = addr + len;
3052 new_vma->vm_pgoff = pgoff;
3053 if (vma_dup_policy(vma, new_vma))
3054 goto out_free_vma;
3055 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
3056 if (anon_vma_clone(new_vma, vma))
3057 goto out_free_mempol;
3058 if (new_vma->vm_file)
3059 get_file(new_vma->vm_file);
3060 if (new_vma->vm_ops && new_vma->vm_ops->open)
3061 new_vma->vm_ops->open(new_vma);
3062 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3063 *need_rmap_locks = false;
3064 }
3065 return new_vma;
3066
3067out_free_mempol:
3068 mpol_put(vma_policy(new_vma));
3069out_free_vma:
3070 kmem_cache_free(vm_area_cachep, new_vma);
3071out:
3072 return NULL;
3073}
3074
3075/*
3076 * Return true if the calling process may expand its vm space by the passed
3077 * number of pages
3078 */
3079bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3080{
3081 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3082 return false;
3083
3084 if (is_data_mapping(flags) &&
3085 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3086 /* Workaround for Valgrind */
3087 if (rlimit(RLIMIT_DATA) == 0 &&
3088 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3089 return true;
3090 if (!ignore_rlimit_data) {
3091 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
3092 current->comm, current->pid,
3093 (mm->data_vm + npages) << PAGE_SHIFT,
3094 rlimit(RLIMIT_DATA));
3095 return false;
3096 }
3097 }
3098
3099 return true;
3100}
3101
3102void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3103{
3104 mm->total_vm += npages;
3105
3106 if (is_exec_mapping(flags))
3107 mm->exec_vm += npages;
3108 else if (is_stack_mapping(flags))
3109 mm->stack_vm += npages;
3110 else if (is_data_mapping(flags))
3111 mm->data_vm += npages;
3112}
3113
3114static int special_mapping_fault(struct vm_area_struct *vma,
3115 struct vm_fault *vmf);
3116
3117/*
3118 * Having a close hook prevents vma merging regardless of flags.
3119 */
3120static void special_mapping_close(struct vm_area_struct *vma)
3121{
3122}
3123
3124static const char *special_mapping_name(struct vm_area_struct *vma)
3125{
3126 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3127}
3128
3129static int special_mapping_mremap(struct vm_area_struct *new_vma)
3130{
3131 struct vm_special_mapping *sm = new_vma->vm_private_data;
3132
3133 if (sm->mremap)
3134 return sm->mremap(sm, new_vma);
3135 return 0;
3136}
3137
3138static const struct vm_operations_struct special_mapping_vmops = {
3139 .close = special_mapping_close,
3140 .fault = special_mapping_fault,
3141 .mremap = special_mapping_mremap,
3142 .name = special_mapping_name,
3143};
3144
3145static const struct vm_operations_struct legacy_special_mapping_vmops = {
3146 .close = special_mapping_close,
3147 .fault = special_mapping_fault,
3148};
3149
3150static int special_mapping_fault(struct vm_area_struct *vma,
3151 struct vm_fault *vmf)
3152{
3153 pgoff_t pgoff;
3154 struct page **pages;
3155
3156 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3157 pages = vma->vm_private_data;
3158 } else {
3159 struct vm_special_mapping *sm = vma->vm_private_data;
3160
3161 if (sm->fault)
3162 return sm->fault(sm, vma, vmf);
3163
3164 pages = sm->pages;
3165 }
3166
3167 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3168 pgoff--;
3169
3170 if (*pages) {
3171 struct page *page = *pages;
3172 get_page(page);
3173 vmf->page = page;
3174 return 0;
3175 }
3176
3177 return VM_FAULT_SIGBUS;
3178}
3179
3180static struct vm_area_struct *__install_special_mapping(
3181 struct mm_struct *mm,
3182 unsigned long addr, unsigned long len,
3183 unsigned long vm_flags, void *priv,
3184 const struct vm_operations_struct *ops)
3185{
3186 int ret;
3187 struct vm_area_struct *vma;
3188
3189 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3190 if (unlikely(vma == NULL))
3191 return ERR_PTR(-ENOMEM);
3192
3193 INIT_LIST_HEAD(&vma->anon_vma_chain);
3194 vma->vm_mm = mm;
3195 vma->vm_start = addr;
3196 vma->vm_end = addr + len;
3197
3198 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3199 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3200
3201 vma->vm_ops = ops;
3202 vma->vm_private_data = priv;
3203
3204 ret = insert_vm_struct(mm, vma);
3205 if (ret)
3206 goto out;
3207
3208 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3209
3210 perf_event_mmap(vma);
3211
3212 return vma;
3213
3214out:
3215 kmem_cache_free(vm_area_cachep, vma);
3216 return ERR_PTR(ret);
3217}
3218
3219bool vma_is_special_mapping(const struct vm_area_struct *vma,
3220 const struct vm_special_mapping *sm)
3221{
3222 return vma->vm_private_data == sm &&
3223 (vma->vm_ops == &special_mapping_vmops ||
3224 vma->vm_ops == &legacy_special_mapping_vmops);
3225}
3226
3227/*
3228 * Called with mm->mmap_sem held for writing.
3229 * Insert a new vma covering the given region, with the given flags.
3230 * Its pages are supplied by the given array of struct page *.
3231 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3232 * The region past the last page supplied will always produce SIGBUS.
3233 * The array pointer and the pages it points to are assumed to stay alive
3234 * for as long as this mapping might exist.
3235 */
3236struct vm_area_struct *_install_special_mapping(
3237 struct mm_struct *mm,
3238 unsigned long addr, unsigned long len,
3239 unsigned long vm_flags, const struct vm_special_mapping *spec)
3240{
3241 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3242 &special_mapping_vmops);
3243}
3244
3245int install_special_mapping(struct mm_struct *mm,
3246 unsigned long addr, unsigned long len,
3247 unsigned long vm_flags, struct page **pages)
3248{
3249 struct vm_area_struct *vma = __install_special_mapping(
3250 mm, addr, len, vm_flags, (void *)pages,
3251 &legacy_special_mapping_vmops);
3252
3253 return PTR_ERR_OR_ZERO(vma);
3254}
3255
3256static DEFINE_MUTEX(mm_all_locks_mutex);
3257
3258static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3259{
3260 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3261 /*
3262 * The LSB of head.next can't change from under us
3263 * because we hold the mm_all_locks_mutex.
3264 */
3265 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3266 /*
3267 * We can safely modify head.next after taking the
3268 * anon_vma->root->rwsem. If some other vma in this mm shares
3269 * the same anon_vma we won't take it again.
3270 *
3271 * No need of atomic instructions here, head.next
3272 * can't change from under us thanks to the
3273 * anon_vma->root->rwsem.
3274 */
3275 if (__test_and_set_bit(0, (unsigned long *)
3276 &anon_vma->root->rb_root.rb_node))
3277 BUG();
3278 }
3279}
3280
3281static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3282{
3283 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3284 /*
3285 * AS_MM_ALL_LOCKS can't change from under us because
3286 * we hold the mm_all_locks_mutex.
3287 *
3288 * Operations on ->flags have to be atomic because
3289 * even if AS_MM_ALL_LOCKS is stable thanks to the
3290 * mm_all_locks_mutex, there may be other cpus
3291 * changing other bitflags in parallel to us.
3292 */
3293 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3294 BUG();
3295 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3296 }
3297}
3298
3299/*
3300 * This operation locks against the VM for all pte/vma/mm related
3301 * operations that could ever happen on a certain mm. This includes
3302 * vmtruncate, try_to_unmap, and all page faults.
3303 *
3304 * The caller must take the mmap_sem in write mode before calling
3305 * mm_take_all_locks(). The caller isn't allowed to release the
3306 * mmap_sem until mm_drop_all_locks() returns.
3307 *
3308 * mmap_sem in write mode is required in order to block all operations
3309 * that could modify pagetables and free pages without need of
3310 * altering the vma layout. It's also needed in write mode to avoid new
3311 * anon_vmas to be associated with existing vmas.
3312 *
3313 * A single task can't take more than one mm_take_all_locks() in a row
3314 * or it would deadlock.
3315 *
3316 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3317 * mapping->flags avoid to take the same lock twice, if more than one
3318 * vma in this mm is backed by the same anon_vma or address_space.
3319 *
3320 * We take locks in following order, accordingly to comment at beginning
3321 * of mm/rmap.c:
3322 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3323 * hugetlb mapping);
3324 * - all i_mmap_rwsem locks;
3325 * - all anon_vma->rwseml
3326 *
3327 * We can take all locks within these types randomly because the VM code
3328 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3329 * mm_all_locks_mutex.
3330 *
3331 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3332 * that may have to take thousand of locks.
3333 *
3334 * mm_take_all_locks() can fail if it's interrupted by signals.
3335 */
3336int mm_take_all_locks(struct mm_struct *mm)
3337{
3338 struct vm_area_struct *vma;
3339 struct anon_vma_chain *avc;
3340
3341 BUG_ON(down_read_trylock(&mm->mmap_sem));
3342
3343 mutex_lock(&mm_all_locks_mutex);
3344
3345 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3346 if (signal_pending(current))
3347 goto out_unlock;
3348 if (vma->vm_file && vma->vm_file->f_mapping &&
3349 is_vm_hugetlb_page(vma))
3350 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3351 }
3352
3353 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3354 if (signal_pending(current))
3355 goto out_unlock;
3356 if (vma->vm_file && vma->vm_file->f_mapping &&
3357 !is_vm_hugetlb_page(vma))
3358 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3359 }
3360
3361 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3362 if (signal_pending(current))
3363 goto out_unlock;
3364 if (vma->anon_vma)
3365 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3366 vm_lock_anon_vma(mm, avc->anon_vma);
3367 }
3368
3369 return 0;
3370
3371out_unlock:
3372 mm_drop_all_locks(mm);
3373 return -EINTR;
3374}
3375
3376static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3377{
3378 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3379 /*
3380 * The LSB of head.next can't change to 0 from under
3381 * us because we hold the mm_all_locks_mutex.
3382 *
3383 * We must however clear the bitflag before unlocking
3384 * the vma so the users using the anon_vma->rb_root will
3385 * never see our bitflag.
3386 *
3387 * No need of atomic instructions here, head.next
3388 * can't change from under us until we release the
3389 * anon_vma->root->rwsem.
3390 */
3391 if (!__test_and_clear_bit(0, (unsigned long *)
3392 &anon_vma->root->rb_root.rb_node))
3393 BUG();
3394 anon_vma_unlock_write(anon_vma);
3395 }
3396}
3397
3398static void vm_unlock_mapping(struct address_space *mapping)
3399{
3400 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3401 /*
3402 * AS_MM_ALL_LOCKS can't change to 0 from under us
3403 * because we hold the mm_all_locks_mutex.
3404 */
3405 i_mmap_unlock_write(mapping);
3406 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3407 &mapping->flags))
3408 BUG();
3409 }
3410}
3411
3412/*
3413 * The mmap_sem cannot be released by the caller until
3414 * mm_drop_all_locks() returns.
3415 */
3416void mm_drop_all_locks(struct mm_struct *mm)
3417{
3418 struct vm_area_struct *vma;
3419 struct anon_vma_chain *avc;
3420
3421 BUG_ON(down_read_trylock(&mm->mmap_sem));
3422 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3423
3424 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3425 if (vma->anon_vma)
3426 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3427 vm_unlock_anon_vma(avc->anon_vma);
3428 if (vma->vm_file && vma->vm_file->f_mapping)
3429 vm_unlock_mapping(vma->vm_file->f_mapping);
3430 }
3431
3432 mutex_unlock(&mm_all_locks_mutex);
3433}
3434
3435/*
3436 * initialise the VMA slab
3437 */
3438void __init mmap_init(void)
3439{
3440 int ret;
3441
3442 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3443 VM_BUG_ON(ret);
3444}
3445
3446/*
3447 * Initialise sysctl_user_reserve_kbytes.
3448 *
3449 * This is intended to prevent a user from starting a single memory hogging
3450 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3451 * mode.
3452 *
3453 * The default value is min(3% of free memory, 128MB)
3454 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3455 */
3456static int init_user_reserve(void)
3457{
3458 unsigned long free_kbytes;
3459
3460 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3461
3462 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3463 return 0;
3464}
3465subsys_initcall(init_user_reserve);
3466
3467/*
3468 * Initialise sysctl_admin_reserve_kbytes.
3469 *
3470 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3471 * to log in and kill a memory hogging process.
3472 *
3473 * Systems with more than 256MB will reserve 8MB, enough to recover
3474 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3475 * only reserve 3% of free pages by default.
3476 */
3477static int init_admin_reserve(void)
3478{
3479 unsigned long free_kbytes;
3480
3481 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3482
3483 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3484 return 0;
3485}
3486subsys_initcall(init_admin_reserve);
3487
3488/*
3489 * Reinititalise user and admin reserves if memory is added or removed.
3490 *
3491 * The default user reserve max is 128MB, and the default max for the
3492 * admin reserve is 8MB. These are usually, but not always, enough to
3493 * enable recovery from a memory hogging process using login/sshd, a shell,
3494 * and tools like top. It may make sense to increase or even disable the
3495 * reserve depending on the existence of swap or variations in the recovery
3496 * tools. So, the admin may have changed them.
3497 *
3498 * If memory is added and the reserves have been eliminated or increased above
3499 * the default max, then we'll trust the admin.
3500 *
3501 * If memory is removed and there isn't enough free memory, then we
3502 * need to reset the reserves.
3503 *
3504 * Otherwise keep the reserve set by the admin.
3505 */
3506static int reserve_mem_notifier(struct notifier_block *nb,
3507 unsigned long action, void *data)
3508{
3509 unsigned long tmp, free_kbytes;
3510
3511 switch (action) {
3512 case MEM_ONLINE:
3513 /* Default max is 128MB. Leave alone if modified by operator. */
3514 tmp = sysctl_user_reserve_kbytes;
3515 if (0 < tmp && tmp < (1UL << 17))
3516 init_user_reserve();
3517
3518 /* Default max is 8MB. Leave alone if modified by operator. */
3519 tmp = sysctl_admin_reserve_kbytes;
3520 if (0 < tmp && tmp < (1UL << 13))
3521 init_admin_reserve();
3522
3523 break;
3524 case MEM_OFFLINE:
3525 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3526
3527 if (sysctl_user_reserve_kbytes > free_kbytes) {
3528 init_user_reserve();
3529 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3530 sysctl_user_reserve_kbytes);
3531 }
3532
3533 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3534 init_admin_reserve();
3535 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3536 sysctl_admin_reserve_kbytes);
3537 }
3538 break;
3539 default:
3540 break;
3541 }
3542 return NOTIFY_OK;
3543}
3544
3545static struct notifier_block reserve_mem_nb = {
3546 .notifier_call = reserve_mem_notifier,
3547};
3548
3549static int __meminit init_reserve_notifier(void)
3550{
3551 if (register_hotmemory_notifier(&reserve_mem_nb))
3552 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3553
3554 return 0;
3555}
3556subsys_initcall(init_reserve_notifier);