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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// 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/vmacache.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/rbtree_augmented.h>
42#include <linux/notifier.h>
43#include <linux/memory.h>
44#include <linux/printk.h>
45#include <linux/userfaultfd_k.h>
46#include <linux/moduleparam.h>
47#include <linux/pkeys.h>
48#include <linux/oom.h>
49#include <linux/sched/mm.h>
50
51#include <linux/uaccess.h>
52#include <asm/cacheflush.h>
53#include <asm/tlb.h>
54#include <asm/mmu_context.h>
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/mmap.h>
58
59#include "internal.h"
60
61#ifndef arch_mmap_check
62#define arch_mmap_check(addr, len, flags) (0)
63#endif
64
65#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
66const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
67const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
68int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
69#endif
70#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
71const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
72const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
73int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
74#endif
75
76static bool ignore_rlimit_data;
77core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
78
79static void unmap_region(struct mm_struct *mm,
80 struct vm_area_struct *vma, struct vm_area_struct *prev,
81 unsigned long start, unsigned long end);
82
83/* description of effects of mapping type and prot in current implementation.
84 * this is due to the limited x86 page protection hardware. The expected
85 * behavior is in parens:
86 *
87 * map_type prot
88 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
89 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
90 * w: (no) no w: (no) no w: (yes) yes w: (no) no
91 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
92 *
93 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
94 * w: (no) no w: (no) no w: (copy) copy w: (no) no
95 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
96 */
97pgprot_t protection_map[16] __ro_after_init = {
98 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
99 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
100};
101
102#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
103static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
104{
105 return prot;
106}
107#endif
108
109pgprot_t vm_get_page_prot(unsigned long vm_flags)
110{
111 pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
112 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
113 pgprot_val(arch_vm_get_page_prot(vm_flags)));
114
115 return arch_filter_pgprot(ret);
116}
117EXPORT_SYMBOL(vm_get_page_prot);
118
119static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
120{
121 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
122}
123
124/* Update vma->vm_page_prot to reflect vma->vm_flags. */
125void vma_set_page_prot(struct vm_area_struct *vma)
126{
127 unsigned long vm_flags = vma->vm_flags;
128 pgprot_t vm_page_prot;
129
130 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
131 if (vma_wants_writenotify(vma, vm_page_prot)) {
132 vm_flags &= ~VM_SHARED;
133 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
134 }
135 /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
136 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
137}
138
139/*
140 * Requires inode->i_mapping->i_mmap_rwsem
141 */
142static void __remove_shared_vm_struct(struct vm_area_struct *vma,
143 struct file *file, struct address_space *mapping)
144{
145 if (vma->vm_flags & VM_DENYWRITE)
146 atomic_inc(&file_inode(file)->i_writecount);
147 if (vma->vm_flags & VM_SHARED)
148 mapping_unmap_writable(mapping);
149
150 flush_dcache_mmap_lock(mapping);
151 vma_interval_tree_remove(vma, &mapping->i_mmap);
152 flush_dcache_mmap_unlock(mapping);
153}
154
155/*
156 * Unlink a file-based vm structure from its interval tree, to hide
157 * vma from rmap and vmtruncate before freeing its page tables.
158 */
159void unlink_file_vma(struct vm_area_struct *vma)
160{
161 struct file *file = vma->vm_file;
162
163 if (file) {
164 struct address_space *mapping = file->f_mapping;
165 i_mmap_lock_write(mapping);
166 __remove_shared_vm_struct(vma, file, mapping);
167 i_mmap_unlock_write(mapping);
168 }
169}
170
171/*
172 * Close a vm structure and free it, returning the next.
173 */
174static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
175{
176 struct vm_area_struct *next = vma->vm_next;
177
178 might_sleep();
179 if (vma->vm_ops && vma->vm_ops->close)
180 vma->vm_ops->close(vma);
181 if (vma->vm_file)
182 fput(vma->vm_file);
183 mpol_put(vma_policy(vma));
184 vm_area_free(vma);
185 return next;
186}
187
188static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
189 struct list_head *uf);
190SYSCALL_DEFINE1(brk, unsigned long, brk)
191{
192 unsigned long retval;
193 unsigned long newbrk, oldbrk, origbrk;
194 struct mm_struct *mm = current->mm;
195 struct vm_area_struct *next;
196 unsigned long min_brk;
197 bool populate;
198 bool downgraded = false;
199 LIST_HEAD(uf);
200
201 if (mmap_write_lock_killable(mm))
202 return -EINTR;
203
204 origbrk = mm->brk;
205
206#ifdef CONFIG_COMPAT_BRK
207 /*
208 * CONFIG_COMPAT_BRK can still be overridden by setting
209 * randomize_va_space to 2, which will still cause mm->start_brk
210 * to be arbitrarily shifted
211 */
212 if (current->brk_randomized)
213 min_brk = mm->start_brk;
214 else
215 min_brk = mm->end_data;
216#else
217 min_brk = mm->start_brk;
218#endif
219 if (brk < min_brk)
220 goto out;
221
222 /*
223 * Check against rlimit here. If this check is done later after the test
224 * of oldbrk with newbrk then it can escape the test and let the data
225 * segment grow beyond its set limit the in case where the limit is
226 * not page aligned -Ram Gupta
227 */
228 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
229 mm->end_data, mm->start_data))
230 goto out;
231
232 newbrk = PAGE_ALIGN(brk);
233 oldbrk = PAGE_ALIGN(mm->brk);
234 if (oldbrk == newbrk) {
235 mm->brk = brk;
236 goto success;
237 }
238
239 /*
240 * Always allow shrinking brk.
241 * __do_munmap() may downgrade mmap_lock to read.
242 */
243 if (brk <= mm->brk) {
244 int ret;
245
246 /*
247 * mm->brk must to be protected by write mmap_lock so update it
248 * before downgrading mmap_lock. When __do_munmap() fails,
249 * mm->brk will be restored from origbrk.
250 */
251 mm->brk = brk;
252 ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
253 if (ret < 0) {
254 mm->brk = origbrk;
255 goto out;
256 } else if (ret == 1) {
257 downgraded = true;
258 }
259 goto success;
260 }
261
262 /* Check against existing mmap mappings. */
263 next = find_vma(mm, oldbrk);
264 if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
265 goto out;
266
267 /* Ok, looks good - let it rip. */
268 if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
269 goto out;
270 mm->brk = brk;
271
272success:
273 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
274 if (downgraded)
275 mmap_read_unlock(mm);
276 else
277 mmap_write_unlock(mm);
278 userfaultfd_unmap_complete(mm, &uf);
279 if (populate)
280 mm_populate(oldbrk, newbrk - oldbrk);
281 return brk;
282
283out:
284 retval = origbrk;
285 mmap_write_unlock(mm);
286 return retval;
287}
288
289static inline unsigned long vma_compute_gap(struct vm_area_struct *vma)
290{
291 unsigned long gap, prev_end;
292
293 /*
294 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
295 * allow two stack_guard_gaps between them here, and when choosing
296 * an unmapped area; whereas when expanding we only require one.
297 * That's a little inconsistent, but keeps the code here simpler.
298 */
299 gap = vm_start_gap(vma);
300 if (vma->vm_prev) {
301 prev_end = vm_end_gap(vma->vm_prev);
302 if (gap > prev_end)
303 gap -= prev_end;
304 else
305 gap = 0;
306 }
307 return gap;
308}
309
310#ifdef CONFIG_DEBUG_VM_RB
311static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma)
312{
313 unsigned long max = vma_compute_gap(vma), subtree_gap;
314 if (vma->vm_rb.rb_left) {
315 subtree_gap = rb_entry(vma->vm_rb.rb_left,
316 struct vm_area_struct, vm_rb)->rb_subtree_gap;
317 if (subtree_gap > max)
318 max = subtree_gap;
319 }
320 if (vma->vm_rb.rb_right) {
321 subtree_gap = rb_entry(vma->vm_rb.rb_right,
322 struct vm_area_struct, vm_rb)->rb_subtree_gap;
323 if (subtree_gap > max)
324 max = subtree_gap;
325 }
326 return max;
327}
328
329static int browse_rb(struct mm_struct *mm)
330{
331 struct rb_root *root = &mm->mm_rb;
332 int i = 0, j, bug = 0;
333 struct rb_node *nd, *pn = NULL;
334 unsigned long prev = 0, pend = 0;
335
336 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
337 struct vm_area_struct *vma;
338 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
339 if (vma->vm_start < prev) {
340 pr_emerg("vm_start %lx < prev %lx\n",
341 vma->vm_start, prev);
342 bug = 1;
343 }
344 if (vma->vm_start < pend) {
345 pr_emerg("vm_start %lx < pend %lx\n",
346 vma->vm_start, pend);
347 bug = 1;
348 }
349 if (vma->vm_start > vma->vm_end) {
350 pr_emerg("vm_start %lx > vm_end %lx\n",
351 vma->vm_start, vma->vm_end);
352 bug = 1;
353 }
354 spin_lock(&mm->page_table_lock);
355 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
356 pr_emerg("free gap %lx, correct %lx\n",
357 vma->rb_subtree_gap,
358 vma_compute_subtree_gap(vma));
359 bug = 1;
360 }
361 spin_unlock(&mm->page_table_lock);
362 i++;
363 pn = nd;
364 prev = vma->vm_start;
365 pend = vma->vm_end;
366 }
367 j = 0;
368 for (nd = pn; nd; nd = rb_prev(nd))
369 j++;
370 if (i != j) {
371 pr_emerg("backwards %d, forwards %d\n", j, i);
372 bug = 1;
373 }
374 return bug ? -1 : i;
375}
376
377static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
378{
379 struct rb_node *nd;
380
381 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
382 struct vm_area_struct *vma;
383 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
384 VM_BUG_ON_VMA(vma != ignore &&
385 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
386 vma);
387 }
388}
389
390static void validate_mm(struct mm_struct *mm)
391{
392 int bug = 0;
393 int i = 0;
394 unsigned long highest_address = 0;
395 struct vm_area_struct *vma = mm->mmap;
396
397 while (vma) {
398 struct anon_vma *anon_vma = vma->anon_vma;
399 struct anon_vma_chain *avc;
400
401 if (anon_vma) {
402 anon_vma_lock_read(anon_vma);
403 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
404 anon_vma_interval_tree_verify(avc);
405 anon_vma_unlock_read(anon_vma);
406 }
407
408 highest_address = vm_end_gap(vma);
409 vma = vma->vm_next;
410 i++;
411 }
412 if (i != mm->map_count) {
413 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
414 bug = 1;
415 }
416 if (highest_address != mm->highest_vm_end) {
417 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
418 mm->highest_vm_end, highest_address);
419 bug = 1;
420 }
421 i = browse_rb(mm);
422 if (i != mm->map_count) {
423 if (i != -1)
424 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
425 bug = 1;
426 }
427 VM_BUG_ON_MM(bug, mm);
428}
429#else
430#define validate_mm_rb(root, ignore) do { } while (0)
431#define validate_mm(mm) do { } while (0)
432#endif
433
434RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks,
435 struct vm_area_struct, vm_rb,
436 unsigned long, rb_subtree_gap, vma_compute_gap)
437
438/*
439 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
440 * vma->vm_prev->vm_end values changed, without modifying the vma's position
441 * in the rbtree.
442 */
443static void vma_gap_update(struct vm_area_struct *vma)
444{
445 /*
446 * As it turns out, RB_DECLARE_CALLBACKS_MAX() already created
447 * a callback function that does exactly what we want.
448 */
449 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
450}
451
452static inline void vma_rb_insert(struct vm_area_struct *vma,
453 struct rb_root *root)
454{
455 /* All rb_subtree_gap values must be consistent prior to insertion */
456 validate_mm_rb(root, NULL);
457
458 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
459}
460
461static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
462{
463 /*
464 * Note rb_erase_augmented is a fairly large inline function,
465 * so make sure we instantiate it only once with our desired
466 * augmented rbtree callbacks.
467 */
468 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
469}
470
471static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
472 struct rb_root *root,
473 struct vm_area_struct *ignore)
474{
475 /*
476 * All rb_subtree_gap values must be consistent prior to erase,
477 * with the possible exception of the "next" vma being erased if
478 * next->vm_start was reduced.
479 */
480 validate_mm_rb(root, ignore);
481
482 __vma_rb_erase(vma, root);
483}
484
485static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
486 struct rb_root *root)
487{
488 /*
489 * All rb_subtree_gap values must be consistent prior to erase,
490 * with the possible exception of the vma being erased.
491 */
492 validate_mm_rb(root, vma);
493
494 __vma_rb_erase(vma, root);
495}
496
497/*
498 * vma has some anon_vma assigned, and is already inserted on that
499 * anon_vma's interval trees.
500 *
501 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
502 * vma must be removed from the anon_vma's interval trees using
503 * anon_vma_interval_tree_pre_update_vma().
504 *
505 * After the update, the vma will be reinserted using
506 * anon_vma_interval_tree_post_update_vma().
507 *
508 * The entire update must be protected by exclusive mmap_lock and by
509 * the root anon_vma's mutex.
510 */
511static inline void
512anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
513{
514 struct anon_vma_chain *avc;
515
516 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
517 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
518}
519
520static inline void
521anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
522{
523 struct anon_vma_chain *avc;
524
525 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
526 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
527}
528
529static int find_vma_links(struct mm_struct *mm, unsigned long addr,
530 unsigned long end, struct vm_area_struct **pprev,
531 struct rb_node ***rb_link, struct rb_node **rb_parent)
532{
533 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
534
535 __rb_link = &mm->mm_rb.rb_node;
536 rb_prev = __rb_parent = NULL;
537
538 while (*__rb_link) {
539 struct vm_area_struct *vma_tmp;
540
541 __rb_parent = *__rb_link;
542 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
543
544 if (vma_tmp->vm_end > addr) {
545 /* Fail if an existing vma overlaps the area */
546 if (vma_tmp->vm_start < end)
547 return -ENOMEM;
548 __rb_link = &__rb_parent->rb_left;
549 } else {
550 rb_prev = __rb_parent;
551 __rb_link = &__rb_parent->rb_right;
552 }
553 }
554
555 *pprev = NULL;
556 if (rb_prev)
557 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
558 *rb_link = __rb_link;
559 *rb_parent = __rb_parent;
560 return 0;
561}
562
563static unsigned long count_vma_pages_range(struct mm_struct *mm,
564 unsigned long addr, unsigned long end)
565{
566 unsigned long nr_pages = 0;
567 struct vm_area_struct *vma;
568
569 /* Find first overlaping mapping */
570 vma = find_vma_intersection(mm, addr, end);
571 if (!vma)
572 return 0;
573
574 nr_pages = (min(end, vma->vm_end) -
575 max(addr, vma->vm_start)) >> PAGE_SHIFT;
576
577 /* Iterate over the rest of the overlaps */
578 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
579 unsigned long overlap_len;
580
581 if (vma->vm_start > end)
582 break;
583
584 overlap_len = min(end, vma->vm_end) - vma->vm_start;
585 nr_pages += overlap_len >> PAGE_SHIFT;
586 }
587
588 return nr_pages;
589}
590
591void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
592 struct rb_node **rb_link, struct rb_node *rb_parent)
593{
594 /* Update tracking information for the gap following the new vma. */
595 if (vma->vm_next)
596 vma_gap_update(vma->vm_next);
597 else
598 mm->highest_vm_end = vm_end_gap(vma);
599
600 /*
601 * vma->vm_prev wasn't known when we followed the rbtree to find the
602 * correct insertion point for that vma. As a result, we could not
603 * update the vma vm_rb parents rb_subtree_gap values on the way down.
604 * So, we first insert the vma with a zero rb_subtree_gap value
605 * (to be consistent with what we did on the way down), and then
606 * immediately update the gap to the correct value. Finally we
607 * rebalance the rbtree after all augmented values have been set.
608 */
609 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
610 vma->rb_subtree_gap = 0;
611 vma_gap_update(vma);
612 vma_rb_insert(vma, &mm->mm_rb);
613}
614
615static void __vma_link_file(struct vm_area_struct *vma)
616{
617 struct file *file;
618
619 file = vma->vm_file;
620 if (file) {
621 struct address_space *mapping = file->f_mapping;
622
623 if (vma->vm_flags & VM_DENYWRITE)
624 atomic_dec(&file_inode(file)->i_writecount);
625 if (vma->vm_flags & VM_SHARED)
626 atomic_inc(&mapping->i_mmap_writable);
627
628 flush_dcache_mmap_lock(mapping);
629 vma_interval_tree_insert(vma, &mapping->i_mmap);
630 flush_dcache_mmap_unlock(mapping);
631 }
632}
633
634static void
635__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
636 struct vm_area_struct *prev, struct rb_node **rb_link,
637 struct rb_node *rb_parent)
638{
639 __vma_link_list(mm, vma, prev);
640 __vma_link_rb(mm, vma, rb_link, rb_parent);
641}
642
643static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
644 struct vm_area_struct *prev, struct rb_node **rb_link,
645 struct rb_node *rb_parent)
646{
647 struct address_space *mapping = NULL;
648
649 if (vma->vm_file) {
650 mapping = vma->vm_file->f_mapping;
651 i_mmap_lock_write(mapping);
652 }
653
654 __vma_link(mm, vma, prev, rb_link, rb_parent);
655 __vma_link_file(vma);
656
657 if (mapping)
658 i_mmap_unlock_write(mapping);
659
660 mm->map_count++;
661 validate_mm(mm);
662}
663
664/*
665 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
666 * mm's list and rbtree. It has already been inserted into the interval tree.
667 */
668static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
669{
670 struct vm_area_struct *prev;
671 struct rb_node **rb_link, *rb_parent;
672
673 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
674 &prev, &rb_link, &rb_parent))
675 BUG();
676 __vma_link(mm, vma, prev, rb_link, rb_parent);
677 mm->map_count++;
678}
679
680static __always_inline void __vma_unlink_common(struct mm_struct *mm,
681 struct vm_area_struct *vma,
682 struct vm_area_struct *ignore)
683{
684 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
685 __vma_unlink_list(mm, vma);
686 /* Kill the cache */
687 vmacache_invalidate(mm);
688}
689
690/*
691 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
692 * is already present in an i_mmap tree without adjusting the tree.
693 * The following helper function should be used when such adjustments
694 * are necessary. The "insert" vma (if any) is to be inserted
695 * before we drop the necessary locks.
696 */
697int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
698 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
699 struct vm_area_struct *expand)
700{
701 struct mm_struct *mm = vma->vm_mm;
702 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
703 struct address_space *mapping = NULL;
704 struct rb_root_cached *root = NULL;
705 struct anon_vma *anon_vma = NULL;
706 struct file *file = vma->vm_file;
707 bool start_changed = false, end_changed = false;
708 long adjust_next = 0;
709 int remove_next = 0;
710
711 if (next && !insert) {
712 struct vm_area_struct *exporter = NULL, *importer = NULL;
713
714 if (end >= next->vm_end) {
715 /*
716 * vma expands, overlapping all the next, and
717 * perhaps the one after too (mprotect case 6).
718 * The only other cases that gets here are
719 * case 1, case 7 and case 8.
720 */
721 if (next == expand) {
722 /*
723 * The only case where we don't expand "vma"
724 * and we expand "next" instead is case 8.
725 */
726 VM_WARN_ON(end != next->vm_end);
727 /*
728 * remove_next == 3 means we're
729 * removing "vma" and that to do so we
730 * swapped "vma" and "next".
731 */
732 remove_next = 3;
733 VM_WARN_ON(file != next->vm_file);
734 swap(vma, next);
735 } else {
736 VM_WARN_ON(expand != vma);
737 /*
738 * case 1, 6, 7, remove_next == 2 is case 6,
739 * remove_next == 1 is case 1 or 7.
740 */
741 remove_next = 1 + (end > next->vm_end);
742 VM_WARN_ON(remove_next == 2 &&
743 end != next->vm_next->vm_end);
744 /* trim end to next, for case 6 first pass */
745 end = next->vm_end;
746 }
747
748 exporter = next;
749 importer = vma;
750
751 /*
752 * If next doesn't have anon_vma, import from vma after
753 * next, if the vma overlaps with it.
754 */
755 if (remove_next == 2 && !next->anon_vma)
756 exporter = next->vm_next;
757
758 } else if (end > next->vm_start) {
759 /*
760 * vma expands, overlapping part of the next:
761 * mprotect case 5 shifting the boundary up.
762 */
763 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
764 exporter = next;
765 importer = vma;
766 VM_WARN_ON(expand != importer);
767 } else if (end < vma->vm_end) {
768 /*
769 * vma shrinks, and !insert tells it's not
770 * split_vma inserting another: so it must be
771 * mprotect case 4 shifting the boundary down.
772 */
773 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
774 exporter = vma;
775 importer = next;
776 VM_WARN_ON(expand != importer);
777 }
778
779 /*
780 * Easily overlooked: when mprotect shifts the boundary,
781 * make sure the expanding vma has anon_vma set if the
782 * shrinking vma had, to cover any anon pages imported.
783 */
784 if (exporter && exporter->anon_vma && !importer->anon_vma) {
785 int error;
786
787 importer->anon_vma = exporter->anon_vma;
788 error = anon_vma_clone(importer, exporter);
789 if (error)
790 return error;
791 }
792 }
793again:
794 vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
795
796 if (file) {
797 mapping = file->f_mapping;
798 root = &mapping->i_mmap;
799 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
800
801 if (adjust_next)
802 uprobe_munmap(next, next->vm_start, next->vm_end);
803
804 i_mmap_lock_write(mapping);
805 if (insert) {
806 /*
807 * Put into interval tree now, so instantiated pages
808 * are visible to arm/parisc __flush_dcache_page
809 * throughout; but we cannot insert into address
810 * space until vma start or end is updated.
811 */
812 __vma_link_file(insert);
813 }
814 }
815
816 anon_vma = vma->anon_vma;
817 if (!anon_vma && adjust_next)
818 anon_vma = next->anon_vma;
819 if (anon_vma) {
820 VM_WARN_ON(adjust_next && next->anon_vma &&
821 anon_vma != next->anon_vma);
822 anon_vma_lock_write(anon_vma);
823 anon_vma_interval_tree_pre_update_vma(vma);
824 if (adjust_next)
825 anon_vma_interval_tree_pre_update_vma(next);
826 }
827
828 if (root) {
829 flush_dcache_mmap_lock(mapping);
830 vma_interval_tree_remove(vma, root);
831 if (adjust_next)
832 vma_interval_tree_remove(next, root);
833 }
834
835 if (start != vma->vm_start) {
836 vma->vm_start = start;
837 start_changed = true;
838 }
839 if (end != vma->vm_end) {
840 vma->vm_end = end;
841 end_changed = true;
842 }
843 vma->vm_pgoff = pgoff;
844 if (adjust_next) {
845 next->vm_start += adjust_next << PAGE_SHIFT;
846 next->vm_pgoff += adjust_next;
847 }
848
849 if (root) {
850 if (adjust_next)
851 vma_interval_tree_insert(next, root);
852 vma_interval_tree_insert(vma, root);
853 flush_dcache_mmap_unlock(mapping);
854 }
855
856 if (remove_next) {
857 /*
858 * vma_merge has merged next into vma, and needs
859 * us to remove next before dropping the locks.
860 */
861 if (remove_next != 3)
862 __vma_unlink_common(mm, next, next);
863 else
864 /*
865 * vma is not before next if they've been
866 * swapped.
867 *
868 * pre-swap() next->vm_start was reduced so
869 * tell validate_mm_rb to ignore pre-swap()
870 * "next" (which is stored in post-swap()
871 * "vma").
872 */
873 __vma_unlink_common(mm, next, vma);
874 if (file)
875 __remove_shared_vm_struct(next, file, mapping);
876 } else if (insert) {
877 /*
878 * split_vma has split insert from vma, and needs
879 * us to insert it before dropping the locks
880 * (it may either follow vma or precede it).
881 */
882 __insert_vm_struct(mm, insert);
883 } else {
884 if (start_changed)
885 vma_gap_update(vma);
886 if (end_changed) {
887 if (!next)
888 mm->highest_vm_end = vm_end_gap(vma);
889 else if (!adjust_next)
890 vma_gap_update(next);
891 }
892 }
893
894 if (anon_vma) {
895 anon_vma_interval_tree_post_update_vma(vma);
896 if (adjust_next)
897 anon_vma_interval_tree_post_update_vma(next);
898 anon_vma_unlock_write(anon_vma);
899 }
900 if (mapping)
901 i_mmap_unlock_write(mapping);
902
903 if (root) {
904 uprobe_mmap(vma);
905
906 if (adjust_next)
907 uprobe_mmap(next);
908 }
909
910 if (remove_next) {
911 if (file) {
912 uprobe_munmap(next, next->vm_start, next->vm_end);
913 fput(file);
914 }
915 if (next->anon_vma)
916 anon_vma_merge(vma, next);
917 mm->map_count--;
918 mpol_put(vma_policy(next));
919 vm_area_free(next);
920 /*
921 * In mprotect's case 6 (see comments on vma_merge),
922 * we must remove another next too. It would clutter
923 * up the code too much to do both in one go.
924 */
925 if (remove_next != 3) {
926 /*
927 * If "next" was removed and vma->vm_end was
928 * expanded (up) over it, in turn
929 * "next->vm_prev->vm_end" changed and the
930 * "vma->vm_next" gap must be updated.
931 */
932 next = vma->vm_next;
933 } else {
934 /*
935 * For the scope of the comment "next" and
936 * "vma" considered pre-swap(): if "vma" was
937 * removed, next->vm_start was expanded (down)
938 * over it and the "next" gap must be updated.
939 * Because of the swap() the post-swap() "vma"
940 * actually points to pre-swap() "next"
941 * (post-swap() "next" as opposed is now a
942 * dangling pointer).
943 */
944 next = vma;
945 }
946 if (remove_next == 2) {
947 remove_next = 1;
948 end = next->vm_end;
949 goto again;
950 }
951 else if (next)
952 vma_gap_update(next);
953 else {
954 /*
955 * If remove_next == 2 we obviously can't
956 * reach this path.
957 *
958 * If remove_next == 3 we can't reach this
959 * path because pre-swap() next is always not
960 * NULL. pre-swap() "next" is not being
961 * removed and its next->vm_end is not altered
962 * (and furthermore "end" already matches
963 * next->vm_end in remove_next == 3).
964 *
965 * We reach this only in the remove_next == 1
966 * case if the "next" vma that was removed was
967 * the highest vma of the mm. However in such
968 * case next->vm_end == "end" and the extended
969 * "vma" has vma->vm_end == next->vm_end so
970 * mm->highest_vm_end doesn't need any update
971 * in remove_next == 1 case.
972 */
973 VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
974 }
975 }
976 if (insert && file)
977 uprobe_mmap(insert);
978
979 validate_mm(mm);
980
981 return 0;
982}
983
984/*
985 * If the vma has a ->close operation then the driver probably needs to release
986 * per-vma resources, so we don't attempt to merge those.
987 */
988static inline int is_mergeable_vma(struct vm_area_struct *vma,
989 struct file *file, unsigned long vm_flags,
990 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
991{
992 /*
993 * VM_SOFTDIRTY should not prevent from VMA merging, if we
994 * match the flags but dirty bit -- the caller should mark
995 * merged VMA as dirty. If dirty bit won't be excluded from
996 * comparison, we increase pressure on the memory system forcing
997 * the kernel to generate new VMAs when old one could be
998 * extended instead.
999 */
1000 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
1001 return 0;
1002 if (vma->vm_file != file)
1003 return 0;
1004 if (vma->vm_ops && vma->vm_ops->close)
1005 return 0;
1006 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
1007 return 0;
1008 return 1;
1009}
1010
1011static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
1012 struct anon_vma *anon_vma2,
1013 struct vm_area_struct *vma)
1014{
1015 /*
1016 * The list_is_singular() test is to avoid merging VMA cloned from
1017 * parents. This can improve scalability caused by anon_vma lock.
1018 */
1019 if ((!anon_vma1 || !anon_vma2) && (!vma ||
1020 list_is_singular(&vma->anon_vma_chain)))
1021 return 1;
1022 return anon_vma1 == anon_vma2;
1023}
1024
1025/*
1026 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1027 * in front of (at a lower virtual address and file offset than) the vma.
1028 *
1029 * We cannot merge two vmas if they have differently assigned (non-NULL)
1030 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1031 *
1032 * We don't check here for the merged mmap wrapping around the end of pagecache
1033 * indices (16TB on ia32) because do_mmap() does not permit mmap's which
1034 * wrap, nor mmaps which cover the final page at index -1UL.
1035 */
1036static int
1037can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1038 struct anon_vma *anon_vma, struct file *file,
1039 pgoff_t vm_pgoff,
1040 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1041{
1042 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1043 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1044 if (vma->vm_pgoff == vm_pgoff)
1045 return 1;
1046 }
1047 return 0;
1048}
1049
1050/*
1051 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1052 * beyond (at a higher virtual address and file offset than) the vma.
1053 *
1054 * We cannot merge two vmas if they have differently assigned (non-NULL)
1055 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1056 */
1057static int
1058can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1059 struct anon_vma *anon_vma, struct file *file,
1060 pgoff_t vm_pgoff,
1061 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1062{
1063 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1064 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1065 pgoff_t vm_pglen;
1066 vm_pglen = vma_pages(vma);
1067 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1068 return 1;
1069 }
1070 return 0;
1071}
1072
1073/*
1074 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1075 * whether that can be merged with its predecessor or its successor.
1076 * Or both (it neatly fills a hole).
1077 *
1078 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1079 * certain not to be mapped by the time vma_merge is called; but when
1080 * called for mprotect, it is certain to be already mapped (either at
1081 * an offset within prev, or at the start of next), and the flags of
1082 * this area are about to be changed to vm_flags - and the no-change
1083 * case has already been eliminated.
1084 *
1085 * The following mprotect cases have to be considered, where AAAA is
1086 * the area passed down from mprotect_fixup, never extending beyond one
1087 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1088 *
1089 * AAAA AAAA AAAA
1090 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN
1091 * cannot merge might become might become
1092 * PPNNNNNNNNNN PPPPPPPPPPNN
1093 * mmap, brk or case 4 below case 5 below
1094 * mremap move:
1095 * AAAA AAAA
1096 * PPPP NNNN PPPPNNNNXXXX
1097 * might become might become
1098 * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
1099 * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or
1100 * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8
1101 *
1102 * It is important for case 8 that the vma NNNN overlapping the
1103 * region AAAA is never going to extended over XXXX. Instead XXXX must
1104 * be extended in region AAAA and NNNN must be removed. This way in
1105 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1106 * rmap_locks, the properties of the merged vma will be already
1107 * correct for the whole merged range. Some of those properties like
1108 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1109 * be correct for the whole merged range immediately after the
1110 * rmap_locks are released. Otherwise if XXXX would be removed and
1111 * NNNN would be extended over the XXXX range, remove_migration_ptes
1112 * or other rmap walkers (if working on addresses beyond the "end"
1113 * parameter) may establish ptes with the wrong permissions of NNNN
1114 * instead of the right permissions of XXXX.
1115 */
1116struct vm_area_struct *vma_merge(struct mm_struct *mm,
1117 struct vm_area_struct *prev, unsigned long addr,
1118 unsigned long end, unsigned long vm_flags,
1119 struct anon_vma *anon_vma, struct file *file,
1120 pgoff_t pgoff, struct mempolicy *policy,
1121 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1122{
1123 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1124 struct vm_area_struct *area, *next;
1125 int err;
1126
1127 /*
1128 * We later require that vma->vm_flags == vm_flags,
1129 * so this tests vma->vm_flags & VM_SPECIAL, too.
1130 */
1131 if (vm_flags & VM_SPECIAL)
1132 return NULL;
1133
1134 if (prev)
1135 next = prev->vm_next;
1136 else
1137 next = mm->mmap;
1138 area = next;
1139 if (area && area->vm_end == end) /* cases 6, 7, 8 */
1140 next = next->vm_next;
1141
1142 /* verify some invariant that must be enforced by the caller */
1143 VM_WARN_ON(prev && addr <= prev->vm_start);
1144 VM_WARN_ON(area && end > area->vm_end);
1145 VM_WARN_ON(addr >= end);
1146
1147 /*
1148 * Can it merge with the predecessor?
1149 */
1150 if (prev && prev->vm_end == addr &&
1151 mpol_equal(vma_policy(prev), policy) &&
1152 can_vma_merge_after(prev, vm_flags,
1153 anon_vma, file, pgoff,
1154 vm_userfaultfd_ctx)) {
1155 /*
1156 * OK, it can. Can we now merge in the successor as well?
1157 */
1158 if (next && end == next->vm_start &&
1159 mpol_equal(policy, vma_policy(next)) &&
1160 can_vma_merge_before(next, vm_flags,
1161 anon_vma, file,
1162 pgoff+pglen,
1163 vm_userfaultfd_ctx) &&
1164 is_mergeable_anon_vma(prev->anon_vma,
1165 next->anon_vma, NULL)) {
1166 /* cases 1, 6 */
1167 err = __vma_adjust(prev, prev->vm_start,
1168 next->vm_end, prev->vm_pgoff, NULL,
1169 prev);
1170 } else /* cases 2, 5, 7 */
1171 err = __vma_adjust(prev, prev->vm_start,
1172 end, prev->vm_pgoff, NULL, prev);
1173 if (err)
1174 return NULL;
1175 khugepaged_enter_vma_merge(prev, vm_flags);
1176 return prev;
1177 }
1178
1179 /*
1180 * Can this new request be merged in front of next?
1181 */
1182 if (next && end == next->vm_start &&
1183 mpol_equal(policy, vma_policy(next)) &&
1184 can_vma_merge_before(next, vm_flags,
1185 anon_vma, file, pgoff+pglen,
1186 vm_userfaultfd_ctx)) {
1187 if (prev && addr < prev->vm_end) /* case 4 */
1188 err = __vma_adjust(prev, prev->vm_start,
1189 addr, prev->vm_pgoff, NULL, next);
1190 else { /* cases 3, 8 */
1191 err = __vma_adjust(area, addr, next->vm_end,
1192 next->vm_pgoff - pglen, NULL, next);
1193 /*
1194 * In case 3 area is already equal to next and
1195 * this is a noop, but in case 8 "area" has
1196 * been removed and next was expanded over it.
1197 */
1198 area = next;
1199 }
1200 if (err)
1201 return NULL;
1202 khugepaged_enter_vma_merge(area, vm_flags);
1203 return area;
1204 }
1205
1206 return NULL;
1207}
1208
1209/*
1210 * Rough compatibility check to quickly see if it's even worth looking
1211 * at sharing an anon_vma.
1212 *
1213 * They need to have the same vm_file, and the flags can only differ
1214 * in things that mprotect may change.
1215 *
1216 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1217 * we can merge the two vma's. For example, we refuse to merge a vma if
1218 * there is a vm_ops->close() function, because that indicates that the
1219 * driver is doing some kind of reference counting. But that doesn't
1220 * really matter for the anon_vma sharing case.
1221 */
1222static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1223{
1224 return a->vm_end == b->vm_start &&
1225 mpol_equal(vma_policy(a), vma_policy(b)) &&
1226 a->vm_file == b->vm_file &&
1227 !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
1228 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1229}
1230
1231/*
1232 * Do some basic sanity checking to see if we can re-use the anon_vma
1233 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1234 * the same as 'old', the other will be the new one that is trying
1235 * to share the anon_vma.
1236 *
1237 * NOTE! This runs with mm_sem held for reading, so it is possible that
1238 * the anon_vma of 'old' is concurrently in the process of being set up
1239 * by another page fault trying to merge _that_. But that's ok: if it
1240 * is being set up, that automatically means that it will be a singleton
1241 * acceptable for merging, so we can do all of this optimistically. But
1242 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1243 *
1244 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1245 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1246 * is to return an anon_vma that is "complex" due to having gone through
1247 * a fork).
1248 *
1249 * We also make sure that the two vma's are compatible (adjacent,
1250 * and with the same memory policies). That's all stable, even with just
1251 * a read lock on the mm_sem.
1252 */
1253static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1254{
1255 if (anon_vma_compatible(a, b)) {
1256 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1257
1258 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1259 return anon_vma;
1260 }
1261 return NULL;
1262}
1263
1264/*
1265 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1266 * neighbouring vmas for a suitable anon_vma, before it goes off
1267 * to allocate a new anon_vma. It checks because a repetitive
1268 * sequence of mprotects and faults may otherwise lead to distinct
1269 * anon_vmas being allocated, preventing vma merge in subsequent
1270 * mprotect.
1271 */
1272struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1273{
1274 struct anon_vma *anon_vma = NULL;
1275
1276 /* Try next first. */
1277 if (vma->vm_next) {
1278 anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
1279 if (anon_vma)
1280 return anon_vma;
1281 }
1282
1283 /* Try prev next. */
1284 if (vma->vm_prev)
1285 anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
1286
1287 /*
1288 * We might reach here with anon_vma == NULL if we can't find
1289 * any reusable anon_vma.
1290 * There's no absolute need to look only at touching neighbours:
1291 * we could search further afield for "compatible" anon_vmas.
1292 * But it would probably just be a waste of time searching,
1293 * or lead to too many vmas hanging off the same anon_vma.
1294 * We're trying to allow mprotect remerging later on,
1295 * not trying to minimize memory used for anon_vmas.
1296 */
1297 return anon_vma;
1298}
1299
1300/*
1301 * If a hint addr is less than mmap_min_addr change hint to be as
1302 * low as possible but still greater than mmap_min_addr
1303 */
1304static inline unsigned long round_hint_to_min(unsigned long hint)
1305{
1306 hint &= PAGE_MASK;
1307 if (((void *)hint != NULL) &&
1308 (hint < mmap_min_addr))
1309 return PAGE_ALIGN(mmap_min_addr);
1310 return hint;
1311}
1312
1313static inline int mlock_future_check(struct mm_struct *mm,
1314 unsigned long flags,
1315 unsigned long len)
1316{
1317 unsigned long locked, lock_limit;
1318
1319 /* mlock MCL_FUTURE? */
1320 if (flags & VM_LOCKED) {
1321 locked = len >> PAGE_SHIFT;
1322 locked += mm->locked_vm;
1323 lock_limit = rlimit(RLIMIT_MEMLOCK);
1324 lock_limit >>= PAGE_SHIFT;
1325 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1326 return -EAGAIN;
1327 }
1328 return 0;
1329}
1330
1331static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1332{
1333 if (S_ISREG(inode->i_mode))
1334 return MAX_LFS_FILESIZE;
1335
1336 if (S_ISBLK(inode->i_mode))
1337 return MAX_LFS_FILESIZE;
1338
1339 if (S_ISSOCK(inode->i_mode))
1340 return MAX_LFS_FILESIZE;
1341
1342 /* Special "we do even unsigned file positions" case */
1343 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1344 return 0;
1345
1346 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1347 return ULONG_MAX;
1348}
1349
1350static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1351 unsigned long pgoff, unsigned long len)
1352{
1353 u64 maxsize = file_mmap_size_max(file, inode);
1354
1355 if (maxsize && len > maxsize)
1356 return false;
1357 maxsize -= len;
1358 if (pgoff > maxsize >> PAGE_SHIFT)
1359 return false;
1360 return true;
1361}
1362
1363/*
1364 * The caller must write-lock current->mm->mmap_lock.
1365 */
1366unsigned long do_mmap(struct file *file, unsigned long addr,
1367 unsigned long len, unsigned long prot,
1368 unsigned long flags, unsigned long pgoff,
1369 unsigned long *populate, struct list_head *uf)
1370{
1371 struct mm_struct *mm = current->mm;
1372 vm_flags_t vm_flags;
1373 int pkey = 0;
1374
1375 *populate = 0;
1376
1377 if (!len)
1378 return -EINVAL;
1379
1380 /*
1381 * Does the application expect PROT_READ to imply PROT_EXEC?
1382 *
1383 * (the exception is when the underlying filesystem is noexec
1384 * mounted, in which case we dont add PROT_EXEC.)
1385 */
1386 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1387 if (!(file && path_noexec(&file->f_path)))
1388 prot |= PROT_EXEC;
1389
1390 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1391 if (flags & MAP_FIXED_NOREPLACE)
1392 flags |= MAP_FIXED;
1393
1394 if (!(flags & MAP_FIXED))
1395 addr = round_hint_to_min(addr);
1396
1397 /* Careful about overflows.. */
1398 len = PAGE_ALIGN(len);
1399 if (!len)
1400 return -ENOMEM;
1401
1402 /* offset overflow? */
1403 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1404 return -EOVERFLOW;
1405
1406 /* Too many mappings? */
1407 if (mm->map_count > sysctl_max_map_count)
1408 return -ENOMEM;
1409
1410 /* Obtain the address to map to. we verify (or select) it and ensure
1411 * that it represents a valid section of the address space.
1412 */
1413 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1414 if (IS_ERR_VALUE(addr))
1415 return addr;
1416
1417 if (flags & MAP_FIXED_NOREPLACE) {
1418 struct vm_area_struct *vma = find_vma(mm, addr);
1419
1420 if (vma && vma->vm_start < addr + len)
1421 return -EEXIST;
1422 }
1423
1424 if (prot == PROT_EXEC) {
1425 pkey = execute_only_pkey(mm);
1426 if (pkey < 0)
1427 pkey = 0;
1428 }
1429
1430 /* Do simple checking here so the lower-level routines won't have
1431 * to. we assume access permissions have been handled by the open
1432 * of the memory object, so we don't do any here.
1433 */
1434 vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1435 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1436
1437 if (flags & MAP_LOCKED)
1438 if (!can_do_mlock())
1439 return -EPERM;
1440
1441 if (mlock_future_check(mm, vm_flags, len))
1442 return -EAGAIN;
1443
1444 if (file) {
1445 struct inode *inode = file_inode(file);
1446 unsigned long flags_mask;
1447
1448 if (!file_mmap_ok(file, inode, pgoff, len))
1449 return -EOVERFLOW;
1450
1451 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1452
1453 switch (flags & MAP_TYPE) {
1454 case MAP_SHARED:
1455 /*
1456 * Force use of MAP_SHARED_VALIDATE with non-legacy
1457 * flags. E.g. MAP_SYNC is dangerous to use with
1458 * MAP_SHARED as you don't know which consistency model
1459 * you will get. We silently ignore unsupported flags
1460 * with MAP_SHARED to preserve backward compatibility.
1461 */
1462 flags &= LEGACY_MAP_MASK;
1463 fallthrough;
1464 case MAP_SHARED_VALIDATE:
1465 if (flags & ~flags_mask)
1466 return -EOPNOTSUPP;
1467 if (prot & PROT_WRITE) {
1468 if (!(file->f_mode & FMODE_WRITE))
1469 return -EACCES;
1470 if (IS_SWAPFILE(file->f_mapping->host))
1471 return -ETXTBSY;
1472 }
1473
1474 /*
1475 * Make sure we don't allow writing to an append-only
1476 * file..
1477 */
1478 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1479 return -EACCES;
1480
1481 /*
1482 * Make sure there are no mandatory locks on the file.
1483 */
1484 if (locks_verify_locked(file))
1485 return -EAGAIN;
1486
1487 vm_flags |= VM_SHARED | VM_MAYSHARE;
1488 if (!(file->f_mode & FMODE_WRITE))
1489 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1490 fallthrough;
1491 case MAP_PRIVATE:
1492 if (!(file->f_mode & FMODE_READ))
1493 return -EACCES;
1494 if (path_noexec(&file->f_path)) {
1495 if (vm_flags & VM_EXEC)
1496 return -EPERM;
1497 vm_flags &= ~VM_MAYEXEC;
1498 }
1499
1500 if (!file->f_op->mmap)
1501 return -ENODEV;
1502 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1503 return -EINVAL;
1504 break;
1505
1506 default:
1507 return -EINVAL;
1508 }
1509 } else {
1510 switch (flags & MAP_TYPE) {
1511 case MAP_SHARED:
1512 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1513 return -EINVAL;
1514 /*
1515 * Ignore pgoff.
1516 */
1517 pgoff = 0;
1518 vm_flags |= VM_SHARED | VM_MAYSHARE;
1519 break;
1520 case MAP_PRIVATE:
1521 /*
1522 * Set pgoff according to addr for anon_vma.
1523 */
1524 pgoff = addr >> PAGE_SHIFT;
1525 break;
1526 default:
1527 return -EINVAL;
1528 }
1529 }
1530
1531 /*
1532 * Set 'VM_NORESERVE' if we should not account for the
1533 * memory use of this mapping.
1534 */
1535 if (flags & MAP_NORESERVE) {
1536 /* We honor MAP_NORESERVE if allowed to overcommit */
1537 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1538 vm_flags |= VM_NORESERVE;
1539
1540 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1541 if (file && is_file_hugepages(file))
1542 vm_flags |= VM_NORESERVE;
1543 }
1544
1545 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1546 if (!IS_ERR_VALUE(addr) &&
1547 ((vm_flags & VM_LOCKED) ||
1548 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1549 *populate = len;
1550 return addr;
1551}
1552
1553unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1554 unsigned long prot, unsigned long flags,
1555 unsigned long fd, unsigned long pgoff)
1556{
1557 struct file *file = NULL;
1558 unsigned long retval;
1559
1560 if (!(flags & MAP_ANONYMOUS)) {
1561 audit_mmap_fd(fd, flags);
1562 file = fget(fd);
1563 if (!file)
1564 return -EBADF;
1565 if (is_file_hugepages(file)) {
1566 len = ALIGN(len, huge_page_size(hstate_file(file)));
1567 } else if (unlikely(flags & MAP_HUGETLB)) {
1568 retval = -EINVAL;
1569 goto out_fput;
1570 }
1571 } else if (flags & MAP_HUGETLB) {
1572 struct user_struct *user = NULL;
1573 struct hstate *hs;
1574
1575 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1576 if (!hs)
1577 return -EINVAL;
1578
1579 len = ALIGN(len, huge_page_size(hs));
1580 /*
1581 * VM_NORESERVE is used because the reservations will be
1582 * taken when vm_ops->mmap() is called
1583 * A dummy user value is used because we are not locking
1584 * memory so no accounting is necessary
1585 */
1586 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1587 VM_NORESERVE,
1588 &user, HUGETLB_ANONHUGE_INODE,
1589 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1590 if (IS_ERR(file))
1591 return PTR_ERR(file);
1592 }
1593
1594 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1595
1596 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1597out_fput:
1598 if (file)
1599 fput(file);
1600 return retval;
1601}
1602
1603SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1604 unsigned long, prot, unsigned long, flags,
1605 unsigned long, fd, unsigned long, pgoff)
1606{
1607 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1608}
1609
1610#ifdef __ARCH_WANT_SYS_OLD_MMAP
1611struct mmap_arg_struct {
1612 unsigned long addr;
1613 unsigned long len;
1614 unsigned long prot;
1615 unsigned long flags;
1616 unsigned long fd;
1617 unsigned long offset;
1618};
1619
1620SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1621{
1622 struct mmap_arg_struct a;
1623
1624 if (copy_from_user(&a, arg, sizeof(a)))
1625 return -EFAULT;
1626 if (offset_in_page(a.offset))
1627 return -EINVAL;
1628
1629 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1630 a.offset >> PAGE_SHIFT);
1631}
1632#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1633
1634/*
1635 * Some shared mappings will want the pages marked read-only
1636 * to track write events. If so, we'll downgrade vm_page_prot
1637 * to the private version (using protection_map[] without the
1638 * VM_SHARED bit).
1639 */
1640int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1641{
1642 vm_flags_t vm_flags = vma->vm_flags;
1643 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1644
1645 /* If it was private or non-writable, the write bit is already clear */
1646 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1647 return 0;
1648
1649 /* The backer wishes to know when pages are first written to? */
1650 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1651 return 1;
1652
1653 /* The open routine did something to the protections that pgprot_modify
1654 * won't preserve? */
1655 if (pgprot_val(vm_page_prot) !=
1656 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1657 return 0;
1658
1659 /* Do we need to track softdirty? */
1660 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1661 return 1;
1662
1663 /* Specialty mapping? */
1664 if (vm_flags & VM_PFNMAP)
1665 return 0;
1666
1667 /* Can the mapping track the dirty pages? */
1668 return vma->vm_file && vma->vm_file->f_mapping &&
1669 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1670}
1671
1672/*
1673 * We account for memory if it's a private writeable mapping,
1674 * not hugepages and VM_NORESERVE wasn't set.
1675 */
1676static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1677{
1678 /*
1679 * hugetlb has its own accounting separate from the core VM
1680 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1681 */
1682 if (file && is_file_hugepages(file))
1683 return 0;
1684
1685 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1686}
1687
1688unsigned long mmap_region(struct file *file, unsigned long addr,
1689 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1690 struct list_head *uf)
1691{
1692 struct mm_struct *mm = current->mm;
1693 struct vm_area_struct *vma, *prev, *merge;
1694 int error;
1695 struct rb_node **rb_link, *rb_parent;
1696 unsigned long charged = 0;
1697
1698 /* Check against address space limit. */
1699 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1700 unsigned long nr_pages;
1701
1702 /*
1703 * MAP_FIXED may remove pages of mappings that intersects with
1704 * requested mapping. Account for the pages it would unmap.
1705 */
1706 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1707
1708 if (!may_expand_vm(mm, vm_flags,
1709 (len >> PAGE_SHIFT) - nr_pages))
1710 return -ENOMEM;
1711 }
1712
1713 /* Clear old maps */
1714 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1715 &rb_parent)) {
1716 if (do_munmap(mm, addr, len, uf))
1717 return -ENOMEM;
1718 }
1719
1720 /*
1721 * Private writable mapping: check memory availability
1722 */
1723 if (accountable_mapping(file, vm_flags)) {
1724 charged = len >> PAGE_SHIFT;
1725 if (security_vm_enough_memory_mm(mm, charged))
1726 return -ENOMEM;
1727 vm_flags |= VM_ACCOUNT;
1728 }
1729
1730 /*
1731 * Can we just expand an old mapping?
1732 */
1733 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1734 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1735 if (vma)
1736 goto out;
1737
1738 /*
1739 * Determine the object being mapped and call the appropriate
1740 * specific mapper. the address has already been validated, but
1741 * not unmapped, but the maps are removed from the list.
1742 */
1743 vma = vm_area_alloc(mm);
1744 if (!vma) {
1745 error = -ENOMEM;
1746 goto unacct_error;
1747 }
1748
1749 vma->vm_start = addr;
1750 vma->vm_end = addr + len;
1751 vma->vm_flags = vm_flags;
1752 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1753 vma->vm_pgoff = pgoff;
1754
1755 if (file) {
1756 if (vm_flags & VM_DENYWRITE) {
1757 error = deny_write_access(file);
1758 if (error)
1759 goto free_vma;
1760 }
1761 if (vm_flags & VM_SHARED) {
1762 error = mapping_map_writable(file->f_mapping);
1763 if (error)
1764 goto allow_write_and_free_vma;
1765 }
1766
1767 /* ->mmap() can change vma->vm_file, but must guarantee that
1768 * vma_link() below can deny write-access if VM_DENYWRITE is set
1769 * and map writably if VM_SHARED is set. This usually means the
1770 * new file must not have been exposed to user-space, yet.
1771 */
1772 vma->vm_file = get_file(file);
1773 error = call_mmap(file, vma);
1774 if (error)
1775 goto unmap_and_free_vma;
1776
1777 /* If vm_flags changed after call_mmap(), we should try merge vma again
1778 * as we may succeed this time.
1779 */
1780 if (unlikely(vm_flags != vma->vm_flags && prev)) {
1781 merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
1782 NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
1783 if (merge) {
1784 /* ->mmap() can change vma->vm_file and fput the original file. So
1785 * fput the vma->vm_file here or we would add an extra fput for file
1786 * and cause general protection fault ultimately.
1787 */
1788 fput(vma->vm_file);
1789 vm_area_free(vma);
1790 vma = merge;
1791 /* Update vm_flags and possible addr to pick up the change. We don't
1792 * warn here if addr changed as the vma is not linked by vma_link().
1793 */
1794 addr = vma->vm_start;
1795 vm_flags = vma->vm_flags;
1796 goto unmap_writable;
1797 }
1798 }
1799
1800 /* Can addr have changed??
1801 *
1802 * Answer: Yes, several device drivers can do it in their
1803 * f_op->mmap method. -DaveM
1804 * Bug: If addr is changed, prev, rb_link, rb_parent should
1805 * be updated for vma_link()
1806 */
1807 WARN_ON_ONCE(addr != vma->vm_start);
1808
1809 addr = vma->vm_start;
1810 vm_flags = vma->vm_flags;
1811 } else if (vm_flags & VM_SHARED) {
1812 error = shmem_zero_setup(vma);
1813 if (error)
1814 goto free_vma;
1815 } else {
1816 vma_set_anonymous(vma);
1817 }
1818
1819 vma_link(mm, vma, prev, rb_link, rb_parent);
1820 /* Once vma denies write, undo our temporary denial count */
1821 if (file) {
1822unmap_writable:
1823 if (vm_flags & VM_SHARED)
1824 mapping_unmap_writable(file->f_mapping);
1825 if (vm_flags & VM_DENYWRITE)
1826 allow_write_access(file);
1827 }
1828 file = vma->vm_file;
1829out:
1830 perf_event_mmap(vma);
1831
1832 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1833 if (vm_flags & VM_LOCKED) {
1834 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
1835 is_vm_hugetlb_page(vma) ||
1836 vma == get_gate_vma(current->mm))
1837 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1838 else
1839 mm->locked_vm += (len >> PAGE_SHIFT);
1840 }
1841
1842 if (file)
1843 uprobe_mmap(vma);
1844
1845 /*
1846 * New (or expanded) vma always get soft dirty status.
1847 * Otherwise user-space soft-dirty page tracker won't
1848 * be able to distinguish situation when vma area unmapped,
1849 * then new mapped in-place (which must be aimed as
1850 * a completely new data area).
1851 */
1852 vma->vm_flags |= VM_SOFTDIRTY;
1853
1854 vma_set_page_prot(vma);
1855
1856 return addr;
1857
1858unmap_and_free_vma:
1859 vma->vm_file = NULL;
1860 fput(file);
1861
1862 /* Undo any partial mapping done by a device driver. */
1863 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1864 charged = 0;
1865 if (vm_flags & VM_SHARED)
1866 mapping_unmap_writable(file->f_mapping);
1867allow_write_and_free_vma:
1868 if (vm_flags & VM_DENYWRITE)
1869 allow_write_access(file);
1870free_vma:
1871 vm_area_free(vma);
1872unacct_error:
1873 if (charged)
1874 vm_unacct_memory(charged);
1875 return error;
1876}
1877
1878static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1879{
1880 /*
1881 * We implement the search by looking for an rbtree node that
1882 * immediately follows a suitable gap. That is,
1883 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1884 * - gap_end = vma->vm_start >= info->low_limit + length;
1885 * - gap_end - gap_start >= length
1886 */
1887
1888 struct mm_struct *mm = current->mm;
1889 struct vm_area_struct *vma;
1890 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1891
1892 /* Adjust search length to account for worst case alignment overhead */
1893 length = info->length + info->align_mask;
1894 if (length < info->length)
1895 return -ENOMEM;
1896
1897 /* Adjust search limits by the desired length */
1898 if (info->high_limit < length)
1899 return -ENOMEM;
1900 high_limit = info->high_limit - length;
1901
1902 if (info->low_limit > high_limit)
1903 return -ENOMEM;
1904 low_limit = info->low_limit + length;
1905
1906 /* Check if rbtree root looks promising */
1907 if (RB_EMPTY_ROOT(&mm->mm_rb))
1908 goto check_highest;
1909 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1910 if (vma->rb_subtree_gap < length)
1911 goto check_highest;
1912
1913 while (true) {
1914 /* Visit left subtree if it looks promising */
1915 gap_end = vm_start_gap(vma);
1916 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1917 struct vm_area_struct *left =
1918 rb_entry(vma->vm_rb.rb_left,
1919 struct vm_area_struct, vm_rb);
1920 if (left->rb_subtree_gap >= length) {
1921 vma = left;
1922 continue;
1923 }
1924 }
1925
1926 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1927check_current:
1928 /* Check if current node has a suitable gap */
1929 if (gap_start > high_limit)
1930 return -ENOMEM;
1931 if (gap_end >= low_limit &&
1932 gap_end > gap_start && gap_end - gap_start >= length)
1933 goto found;
1934
1935 /* Visit right subtree if it looks promising */
1936 if (vma->vm_rb.rb_right) {
1937 struct vm_area_struct *right =
1938 rb_entry(vma->vm_rb.rb_right,
1939 struct vm_area_struct, vm_rb);
1940 if (right->rb_subtree_gap >= length) {
1941 vma = right;
1942 continue;
1943 }
1944 }
1945
1946 /* Go back up the rbtree to find next candidate node */
1947 while (true) {
1948 struct rb_node *prev = &vma->vm_rb;
1949 if (!rb_parent(prev))
1950 goto check_highest;
1951 vma = rb_entry(rb_parent(prev),
1952 struct vm_area_struct, vm_rb);
1953 if (prev == vma->vm_rb.rb_left) {
1954 gap_start = vm_end_gap(vma->vm_prev);
1955 gap_end = vm_start_gap(vma);
1956 goto check_current;
1957 }
1958 }
1959 }
1960
1961check_highest:
1962 /* Check highest gap, which does not precede any rbtree node */
1963 gap_start = mm->highest_vm_end;
1964 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1965 if (gap_start > high_limit)
1966 return -ENOMEM;
1967
1968found:
1969 /* We found a suitable gap. Clip it with the original low_limit. */
1970 if (gap_start < info->low_limit)
1971 gap_start = info->low_limit;
1972
1973 /* Adjust gap address to the desired alignment */
1974 gap_start += (info->align_offset - gap_start) & info->align_mask;
1975
1976 VM_BUG_ON(gap_start + info->length > info->high_limit);
1977 VM_BUG_ON(gap_start + info->length > gap_end);
1978 return gap_start;
1979}
1980
1981static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1982{
1983 struct mm_struct *mm = current->mm;
1984 struct vm_area_struct *vma;
1985 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1986
1987 /* Adjust search length to account for worst case alignment overhead */
1988 length = info->length + info->align_mask;
1989 if (length < info->length)
1990 return -ENOMEM;
1991
1992 /*
1993 * Adjust search limits by the desired length.
1994 * See implementation comment at top of unmapped_area().
1995 */
1996 gap_end = info->high_limit;
1997 if (gap_end < length)
1998 return -ENOMEM;
1999 high_limit = gap_end - length;
2000
2001 if (info->low_limit > high_limit)
2002 return -ENOMEM;
2003 low_limit = info->low_limit + length;
2004
2005 /* Check highest gap, which does not precede any rbtree node */
2006 gap_start = mm->highest_vm_end;
2007 if (gap_start <= high_limit)
2008 goto found_highest;
2009
2010 /* Check if rbtree root looks promising */
2011 if (RB_EMPTY_ROOT(&mm->mm_rb))
2012 return -ENOMEM;
2013 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
2014 if (vma->rb_subtree_gap < length)
2015 return -ENOMEM;
2016
2017 while (true) {
2018 /* Visit right subtree if it looks promising */
2019 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
2020 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
2021 struct vm_area_struct *right =
2022 rb_entry(vma->vm_rb.rb_right,
2023 struct vm_area_struct, vm_rb);
2024 if (right->rb_subtree_gap >= length) {
2025 vma = right;
2026 continue;
2027 }
2028 }
2029
2030check_current:
2031 /* Check if current node has a suitable gap */
2032 gap_end = vm_start_gap(vma);
2033 if (gap_end < low_limit)
2034 return -ENOMEM;
2035 if (gap_start <= high_limit &&
2036 gap_end > gap_start && gap_end - gap_start >= length)
2037 goto found;
2038
2039 /* Visit left subtree if it looks promising */
2040 if (vma->vm_rb.rb_left) {
2041 struct vm_area_struct *left =
2042 rb_entry(vma->vm_rb.rb_left,
2043 struct vm_area_struct, vm_rb);
2044 if (left->rb_subtree_gap >= length) {
2045 vma = left;
2046 continue;
2047 }
2048 }
2049
2050 /* Go back up the rbtree to find next candidate node */
2051 while (true) {
2052 struct rb_node *prev = &vma->vm_rb;
2053 if (!rb_parent(prev))
2054 return -ENOMEM;
2055 vma = rb_entry(rb_parent(prev),
2056 struct vm_area_struct, vm_rb);
2057 if (prev == vma->vm_rb.rb_right) {
2058 gap_start = vma->vm_prev ?
2059 vm_end_gap(vma->vm_prev) : 0;
2060 goto check_current;
2061 }
2062 }
2063 }
2064
2065found:
2066 /* We found a suitable gap. Clip it with the original high_limit. */
2067 if (gap_end > info->high_limit)
2068 gap_end = info->high_limit;
2069
2070found_highest:
2071 /* Compute highest gap address at the desired alignment */
2072 gap_end -= info->length;
2073 gap_end -= (gap_end - info->align_offset) & info->align_mask;
2074
2075 VM_BUG_ON(gap_end < info->low_limit);
2076 VM_BUG_ON(gap_end < gap_start);
2077 return gap_end;
2078}
2079
2080/*
2081 * Search for an unmapped address range.
2082 *
2083 * We are looking for a range that:
2084 * - does not intersect with any VMA;
2085 * - is contained within the [low_limit, high_limit) interval;
2086 * - is at least the desired size.
2087 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
2088 */
2089unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
2090{
2091 unsigned long addr;
2092
2093 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
2094 addr = unmapped_area_topdown(info);
2095 else
2096 addr = unmapped_area(info);
2097
2098 trace_vm_unmapped_area(addr, info);
2099 return addr;
2100}
2101
2102#ifndef arch_get_mmap_end
2103#define arch_get_mmap_end(addr) (TASK_SIZE)
2104#endif
2105
2106#ifndef arch_get_mmap_base
2107#define arch_get_mmap_base(addr, base) (base)
2108#endif
2109
2110/* Get an address range which is currently unmapped.
2111 * For shmat() with addr=0.
2112 *
2113 * Ugly calling convention alert:
2114 * Return value with the low bits set means error value,
2115 * ie
2116 * if (ret & ~PAGE_MASK)
2117 * error = ret;
2118 *
2119 * This function "knows" that -ENOMEM has the bits set.
2120 */
2121#ifndef HAVE_ARCH_UNMAPPED_AREA
2122unsigned long
2123arch_get_unmapped_area(struct file *filp, unsigned long addr,
2124 unsigned long len, unsigned long pgoff, unsigned long flags)
2125{
2126 struct mm_struct *mm = current->mm;
2127 struct vm_area_struct *vma, *prev;
2128 struct vm_unmapped_area_info info;
2129 const unsigned long mmap_end = arch_get_mmap_end(addr);
2130
2131 if (len > mmap_end - mmap_min_addr)
2132 return -ENOMEM;
2133
2134 if (flags & MAP_FIXED)
2135 return addr;
2136
2137 if (addr) {
2138 addr = PAGE_ALIGN(addr);
2139 vma = find_vma_prev(mm, addr, &prev);
2140 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2141 (!vma || addr + len <= vm_start_gap(vma)) &&
2142 (!prev || addr >= vm_end_gap(prev)))
2143 return addr;
2144 }
2145
2146 info.flags = 0;
2147 info.length = len;
2148 info.low_limit = mm->mmap_base;
2149 info.high_limit = mmap_end;
2150 info.align_mask = 0;
2151 info.align_offset = 0;
2152 return vm_unmapped_area(&info);
2153}
2154#endif
2155
2156/*
2157 * This mmap-allocator allocates new areas top-down from below the
2158 * stack's low limit (the base):
2159 */
2160#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2161unsigned long
2162arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
2163 unsigned long len, unsigned long pgoff,
2164 unsigned long flags)
2165{
2166 struct vm_area_struct *vma, *prev;
2167 struct mm_struct *mm = current->mm;
2168 struct vm_unmapped_area_info info;
2169 const unsigned long mmap_end = arch_get_mmap_end(addr);
2170
2171 /* requested length too big for entire address space */
2172 if (len > mmap_end - mmap_min_addr)
2173 return -ENOMEM;
2174
2175 if (flags & MAP_FIXED)
2176 return addr;
2177
2178 /* requesting a specific address */
2179 if (addr) {
2180 addr = PAGE_ALIGN(addr);
2181 vma = find_vma_prev(mm, addr, &prev);
2182 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2183 (!vma || addr + len <= vm_start_gap(vma)) &&
2184 (!prev || addr >= vm_end_gap(prev)))
2185 return addr;
2186 }
2187
2188 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2189 info.length = len;
2190 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2191 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
2192 info.align_mask = 0;
2193 info.align_offset = 0;
2194 addr = vm_unmapped_area(&info);
2195
2196 /*
2197 * A failed mmap() very likely causes application failure,
2198 * so fall back to the bottom-up function here. This scenario
2199 * can happen with large stack limits and large mmap()
2200 * allocations.
2201 */
2202 if (offset_in_page(addr)) {
2203 VM_BUG_ON(addr != -ENOMEM);
2204 info.flags = 0;
2205 info.low_limit = TASK_UNMAPPED_BASE;
2206 info.high_limit = mmap_end;
2207 addr = vm_unmapped_area(&info);
2208 }
2209
2210 return addr;
2211}
2212#endif
2213
2214unsigned long
2215get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2216 unsigned long pgoff, unsigned long flags)
2217{
2218 unsigned long (*get_area)(struct file *, unsigned long,
2219 unsigned long, unsigned long, unsigned long);
2220
2221 unsigned long error = arch_mmap_check(addr, len, flags);
2222 if (error)
2223 return error;
2224
2225 /* Careful about overflows.. */
2226 if (len > TASK_SIZE)
2227 return -ENOMEM;
2228
2229 get_area = current->mm->get_unmapped_area;
2230 if (file) {
2231 if (file->f_op->get_unmapped_area)
2232 get_area = file->f_op->get_unmapped_area;
2233 } else if (flags & MAP_SHARED) {
2234 /*
2235 * mmap_region() will call shmem_zero_setup() to create a file,
2236 * so use shmem's get_unmapped_area in case it can be huge.
2237 * do_mmap() will clear pgoff, so match alignment.
2238 */
2239 pgoff = 0;
2240 get_area = shmem_get_unmapped_area;
2241 }
2242
2243 addr = get_area(file, addr, len, pgoff, flags);
2244 if (IS_ERR_VALUE(addr))
2245 return addr;
2246
2247 if (addr > TASK_SIZE - len)
2248 return -ENOMEM;
2249 if (offset_in_page(addr))
2250 return -EINVAL;
2251
2252 error = security_mmap_addr(addr);
2253 return error ? error : addr;
2254}
2255
2256EXPORT_SYMBOL(get_unmapped_area);
2257
2258/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2259struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2260{
2261 struct rb_node *rb_node;
2262 struct vm_area_struct *vma;
2263
2264 /* Check the cache first. */
2265 vma = vmacache_find(mm, addr);
2266 if (likely(vma))
2267 return vma;
2268
2269 rb_node = mm->mm_rb.rb_node;
2270
2271 while (rb_node) {
2272 struct vm_area_struct *tmp;
2273
2274 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2275
2276 if (tmp->vm_end > addr) {
2277 vma = tmp;
2278 if (tmp->vm_start <= addr)
2279 break;
2280 rb_node = rb_node->rb_left;
2281 } else
2282 rb_node = rb_node->rb_right;
2283 }
2284
2285 if (vma)
2286 vmacache_update(addr, vma);
2287 return vma;
2288}
2289
2290EXPORT_SYMBOL(find_vma);
2291
2292/*
2293 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2294 */
2295struct vm_area_struct *
2296find_vma_prev(struct mm_struct *mm, unsigned long addr,
2297 struct vm_area_struct **pprev)
2298{
2299 struct vm_area_struct *vma;
2300
2301 vma = find_vma(mm, addr);
2302 if (vma) {
2303 *pprev = vma->vm_prev;
2304 } else {
2305 struct rb_node *rb_node = rb_last(&mm->mm_rb);
2306
2307 *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
2308 }
2309 return vma;
2310}
2311
2312/*
2313 * Verify that the stack growth is acceptable and
2314 * update accounting. This is shared with both the
2315 * grow-up and grow-down cases.
2316 */
2317static int acct_stack_growth(struct vm_area_struct *vma,
2318 unsigned long size, unsigned long grow)
2319{
2320 struct mm_struct *mm = vma->vm_mm;
2321 unsigned long new_start;
2322
2323 /* address space limit tests */
2324 if (!may_expand_vm(mm, vma->vm_flags, grow))
2325 return -ENOMEM;
2326
2327 /* Stack limit test */
2328 if (size > rlimit(RLIMIT_STACK))
2329 return -ENOMEM;
2330
2331 /* mlock limit tests */
2332 if (vma->vm_flags & VM_LOCKED) {
2333 unsigned long locked;
2334 unsigned long limit;
2335 locked = mm->locked_vm + grow;
2336 limit = rlimit(RLIMIT_MEMLOCK);
2337 limit >>= PAGE_SHIFT;
2338 if (locked > limit && !capable(CAP_IPC_LOCK))
2339 return -ENOMEM;
2340 }
2341
2342 /* Check to ensure the stack will not grow into a hugetlb-only region */
2343 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2344 vma->vm_end - size;
2345 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2346 return -EFAULT;
2347
2348 /*
2349 * Overcommit.. This must be the final test, as it will
2350 * update security statistics.
2351 */
2352 if (security_vm_enough_memory_mm(mm, grow))
2353 return -ENOMEM;
2354
2355 return 0;
2356}
2357
2358#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2359/*
2360 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2361 * vma is the last one with address > vma->vm_end. Have to extend vma.
2362 */
2363int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2364{
2365 struct mm_struct *mm = vma->vm_mm;
2366 struct vm_area_struct *next;
2367 unsigned long gap_addr;
2368 int error = 0;
2369
2370 if (!(vma->vm_flags & VM_GROWSUP))
2371 return -EFAULT;
2372
2373 /* Guard against exceeding limits of the address space. */
2374 address &= PAGE_MASK;
2375 if (address >= (TASK_SIZE & PAGE_MASK))
2376 return -ENOMEM;
2377 address += PAGE_SIZE;
2378
2379 /* Enforce stack_guard_gap */
2380 gap_addr = address + stack_guard_gap;
2381
2382 /* Guard against overflow */
2383 if (gap_addr < address || gap_addr > TASK_SIZE)
2384 gap_addr = TASK_SIZE;
2385
2386 next = vma->vm_next;
2387 if (next && next->vm_start < gap_addr && vma_is_accessible(next)) {
2388 if (!(next->vm_flags & VM_GROWSUP))
2389 return -ENOMEM;
2390 /* Check that both stack segments have the same anon_vma? */
2391 }
2392
2393 /* We must make sure the anon_vma is allocated. */
2394 if (unlikely(anon_vma_prepare(vma)))
2395 return -ENOMEM;
2396
2397 /*
2398 * vma->vm_start/vm_end cannot change under us because the caller
2399 * is required to hold the mmap_lock in read mode. We need the
2400 * anon_vma lock to serialize against concurrent expand_stacks.
2401 */
2402 anon_vma_lock_write(vma->anon_vma);
2403
2404 /* Somebody else might have raced and expanded it already */
2405 if (address > vma->vm_end) {
2406 unsigned long size, grow;
2407
2408 size = address - vma->vm_start;
2409 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2410
2411 error = -ENOMEM;
2412 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2413 error = acct_stack_growth(vma, size, grow);
2414 if (!error) {
2415 /*
2416 * vma_gap_update() doesn't support concurrent
2417 * updates, but we only hold a shared mmap_lock
2418 * lock here, so we need to protect against
2419 * concurrent vma expansions.
2420 * anon_vma_lock_write() doesn't help here, as
2421 * we don't guarantee that all growable vmas
2422 * in a mm share the same root anon vma.
2423 * So, we reuse mm->page_table_lock to guard
2424 * against concurrent vma expansions.
2425 */
2426 spin_lock(&mm->page_table_lock);
2427 if (vma->vm_flags & VM_LOCKED)
2428 mm->locked_vm += grow;
2429 vm_stat_account(mm, vma->vm_flags, grow);
2430 anon_vma_interval_tree_pre_update_vma(vma);
2431 vma->vm_end = address;
2432 anon_vma_interval_tree_post_update_vma(vma);
2433 if (vma->vm_next)
2434 vma_gap_update(vma->vm_next);
2435 else
2436 mm->highest_vm_end = vm_end_gap(vma);
2437 spin_unlock(&mm->page_table_lock);
2438
2439 perf_event_mmap(vma);
2440 }
2441 }
2442 }
2443 anon_vma_unlock_write(vma->anon_vma);
2444 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2445 validate_mm(mm);
2446 return error;
2447}
2448#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2449
2450/*
2451 * vma is the first one with address < vma->vm_start. Have to extend vma.
2452 */
2453int expand_downwards(struct vm_area_struct *vma,
2454 unsigned long address)
2455{
2456 struct mm_struct *mm = vma->vm_mm;
2457 struct vm_area_struct *prev;
2458 int error = 0;
2459
2460 address &= PAGE_MASK;
2461 if (address < mmap_min_addr)
2462 return -EPERM;
2463
2464 /* Enforce stack_guard_gap */
2465 prev = vma->vm_prev;
2466 /* Check that both stack segments have the same anon_vma? */
2467 if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
2468 vma_is_accessible(prev)) {
2469 if (address - prev->vm_end < stack_guard_gap)
2470 return -ENOMEM;
2471 }
2472
2473 /* We must make sure the anon_vma is allocated. */
2474 if (unlikely(anon_vma_prepare(vma)))
2475 return -ENOMEM;
2476
2477 /*
2478 * vma->vm_start/vm_end cannot change under us because the caller
2479 * is required to hold the mmap_lock in read mode. We need the
2480 * anon_vma lock to serialize against concurrent expand_stacks.
2481 */
2482 anon_vma_lock_write(vma->anon_vma);
2483
2484 /* Somebody else might have raced and expanded it already */
2485 if (address < vma->vm_start) {
2486 unsigned long size, grow;
2487
2488 size = vma->vm_end - address;
2489 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2490
2491 error = -ENOMEM;
2492 if (grow <= vma->vm_pgoff) {
2493 error = acct_stack_growth(vma, size, grow);
2494 if (!error) {
2495 /*
2496 * vma_gap_update() doesn't support concurrent
2497 * updates, but we only hold a shared mmap_lock
2498 * lock here, so we need to protect against
2499 * concurrent vma expansions.
2500 * anon_vma_lock_write() doesn't help here, as
2501 * we don't guarantee that all growable vmas
2502 * in a mm share the same root anon vma.
2503 * So, we reuse mm->page_table_lock to guard
2504 * against concurrent vma expansions.
2505 */
2506 spin_lock(&mm->page_table_lock);
2507 if (vma->vm_flags & VM_LOCKED)
2508 mm->locked_vm += grow;
2509 vm_stat_account(mm, vma->vm_flags, grow);
2510 anon_vma_interval_tree_pre_update_vma(vma);
2511 vma->vm_start = address;
2512 vma->vm_pgoff -= grow;
2513 anon_vma_interval_tree_post_update_vma(vma);
2514 vma_gap_update(vma);
2515 spin_unlock(&mm->page_table_lock);
2516
2517 perf_event_mmap(vma);
2518 }
2519 }
2520 }
2521 anon_vma_unlock_write(vma->anon_vma);
2522 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2523 validate_mm(mm);
2524 return error;
2525}
2526
2527/* enforced gap between the expanding stack and other mappings. */
2528unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2529
2530static int __init cmdline_parse_stack_guard_gap(char *p)
2531{
2532 unsigned long val;
2533 char *endptr;
2534
2535 val = simple_strtoul(p, &endptr, 10);
2536 if (!*endptr)
2537 stack_guard_gap = val << PAGE_SHIFT;
2538
2539 return 0;
2540}
2541__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2542
2543#ifdef CONFIG_STACK_GROWSUP
2544int expand_stack(struct vm_area_struct *vma, unsigned long address)
2545{
2546 return expand_upwards(vma, address);
2547}
2548
2549struct vm_area_struct *
2550find_extend_vma(struct mm_struct *mm, unsigned long addr)
2551{
2552 struct vm_area_struct *vma, *prev;
2553
2554 addr &= PAGE_MASK;
2555 vma = find_vma_prev(mm, addr, &prev);
2556 if (vma && (vma->vm_start <= addr))
2557 return vma;
2558 /* don't alter vm_end if the coredump is running */
2559 if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr))
2560 return NULL;
2561 if (prev->vm_flags & VM_LOCKED)
2562 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2563 return prev;
2564}
2565#else
2566int expand_stack(struct vm_area_struct *vma, unsigned long address)
2567{
2568 return expand_downwards(vma, address);
2569}
2570
2571struct vm_area_struct *
2572find_extend_vma(struct mm_struct *mm, unsigned long addr)
2573{
2574 struct vm_area_struct *vma;
2575 unsigned long start;
2576
2577 addr &= PAGE_MASK;
2578 vma = find_vma(mm, addr);
2579 if (!vma)
2580 return NULL;
2581 if (vma->vm_start <= addr)
2582 return vma;
2583 if (!(vma->vm_flags & VM_GROWSDOWN))
2584 return NULL;
2585 /* don't alter vm_start if the coredump is running */
2586 if (!mmget_still_valid(mm))
2587 return NULL;
2588 start = vma->vm_start;
2589 if (expand_stack(vma, addr))
2590 return NULL;
2591 if (vma->vm_flags & VM_LOCKED)
2592 populate_vma_page_range(vma, addr, start, NULL);
2593 return vma;
2594}
2595#endif
2596
2597EXPORT_SYMBOL_GPL(find_extend_vma);
2598
2599/*
2600 * Ok - we have the memory areas we should free on the vma list,
2601 * so release them, and do the vma updates.
2602 *
2603 * Called with the mm semaphore held.
2604 */
2605static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2606{
2607 unsigned long nr_accounted = 0;
2608
2609 /* Update high watermark before we lower total_vm */
2610 update_hiwater_vm(mm);
2611 do {
2612 long nrpages = vma_pages(vma);
2613
2614 if (vma->vm_flags & VM_ACCOUNT)
2615 nr_accounted += nrpages;
2616 vm_stat_account(mm, vma->vm_flags, -nrpages);
2617 vma = remove_vma(vma);
2618 } while (vma);
2619 vm_unacct_memory(nr_accounted);
2620 validate_mm(mm);
2621}
2622
2623/*
2624 * Get rid of page table information in the indicated region.
2625 *
2626 * Called with the mm semaphore held.
2627 */
2628static void unmap_region(struct mm_struct *mm,
2629 struct vm_area_struct *vma, struct vm_area_struct *prev,
2630 unsigned long start, unsigned long end)
2631{
2632 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2633 struct mmu_gather tlb;
2634
2635 lru_add_drain();
2636 tlb_gather_mmu(&tlb, mm, start, end);
2637 update_hiwater_rss(mm);
2638 unmap_vmas(&tlb, vma, start, end);
2639 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2640 next ? next->vm_start : USER_PGTABLES_CEILING);
2641 tlb_finish_mmu(&tlb, start, end);
2642}
2643
2644/*
2645 * Create a list of vma's touched by the unmap, removing them from the mm's
2646 * vma list as we go..
2647 */
2648static bool
2649detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2650 struct vm_area_struct *prev, unsigned long end)
2651{
2652 struct vm_area_struct **insertion_point;
2653 struct vm_area_struct *tail_vma = NULL;
2654
2655 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2656 vma->vm_prev = NULL;
2657 do {
2658 vma_rb_erase(vma, &mm->mm_rb);
2659 mm->map_count--;
2660 tail_vma = vma;
2661 vma = vma->vm_next;
2662 } while (vma && vma->vm_start < end);
2663 *insertion_point = vma;
2664 if (vma) {
2665 vma->vm_prev = prev;
2666 vma_gap_update(vma);
2667 } else
2668 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
2669 tail_vma->vm_next = NULL;
2670
2671 /* Kill the cache */
2672 vmacache_invalidate(mm);
2673
2674 /*
2675 * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
2676 * VM_GROWSUP VMA. Such VMAs can change their size under
2677 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
2678 */
2679 if (vma && (vma->vm_flags & VM_GROWSDOWN))
2680 return false;
2681 if (prev && (prev->vm_flags & VM_GROWSUP))
2682 return false;
2683 return true;
2684}
2685
2686/*
2687 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2688 * has already been checked or doesn't make sense to fail.
2689 */
2690int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2691 unsigned long addr, int new_below)
2692{
2693 struct vm_area_struct *new;
2694 int err;
2695
2696 if (vma->vm_ops && vma->vm_ops->split) {
2697 err = vma->vm_ops->split(vma, addr);
2698 if (err)
2699 return err;
2700 }
2701
2702 new = vm_area_dup(vma);
2703 if (!new)
2704 return -ENOMEM;
2705
2706 if (new_below)
2707 new->vm_end = addr;
2708 else {
2709 new->vm_start = addr;
2710 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2711 }
2712
2713 err = vma_dup_policy(vma, new);
2714 if (err)
2715 goto out_free_vma;
2716
2717 err = anon_vma_clone(new, vma);
2718 if (err)
2719 goto out_free_mpol;
2720
2721 if (new->vm_file)
2722 get_file(new->vm_file);
2723
2724 if (new->vm_ops && new->vm_ops->open)
2725 new->vm_ops->open(new);
2726
2727 if (new_below)
2728 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2729 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2730 else
2731 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2732
2733 /* Success. */
2734 if (!err)
2735 return 0;
2736
2737 /* Clean everything up if vma_adjust failed. */
2738 if (new->vm_ops && new->vm_ops->close)
2739 new->vm_ops->close(new);
2740 if (new->vm_file)
2741 fput(new->vm_file);
2742 unlink_anon_vmas(new);
2743 out_free_mpol:
2744 mpol_put(vma_policy(new));
2745 out_free_vma:
2746 vm_area_free(new);
2747 return err;
2748}
2749
2750/*
2751 * Split a vma into two pieces at address 'addr', a new vma is allocated
2752 * either for the first part or the tail.
2753 */
2754int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2755 unsigned long addr, int new_below)
2756{
2757 if (mm->map_count >= sysctl_max_map_count)
2758 return -ENOMEM;
2759
2760 return __split_vma(mm, vma, addr, new_below);
2761}
2762
2763/* Munmap is split into 2 main parts -- this part which finds
2764 * what needs doing, and the areas themselves, which do the
2765 * work. This now handles partial unmappings.
2766 * Jeremy Fitzhardinge <jeremy@goop.org>
2767 */
2768int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2769 struct list_head *uf, bool downgrade)
2770{
2771 unsigned long end;
2772 struct vm_area_struct *vma, *prev, *last;
2773
2774 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2775 return -EINVAL;
2776
2777 len = PAGE_ALIGN(len);
2778 end = start + len;
2779 if (len == 0)
2780 return -EINVAL;
2781
2782 /*
2783 * arch_unmap() might do unmaps itself. It must be called
2784 * and finish any rbtree manipulation before this code
2785 * runs and also starts to manipulate the rbtree.
2786 */
2787 arch_unmap(mm, start, end);
2788
2789 /* Find the first overlapping VMA */
2790 vma = find_vma(mm, start);
2791 if (!vma)
2792 return 0;
2793 prev = vma->vm_prev;
2794 /* we have start < vma->vm_end */
2795
2796 /* if it doesn't overlap, we have nothing.. */
2797 if (vma->vm_start >= end)
2798 return 0;
2799
2800 /*
2801 * If we need to split any vma, do it now to save pain later.
2802 *
2803 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2804 * unmapped vm_area_struct will remain in use: so lower split_vma
2805 * places tmp vma above, and higher split_vma places tmp vma below.
2806 */
2807 if (start > vma->vm_start) {
2808 int error;
2809
2810 /*
2811 * Make sure that map_count on return from munmap() will
2812 * not exceed its limit; but let map_count go just above
2813 * its limit temporarily, to help free resources as expected.
2814 */
2815 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2816 return -ENOMEM;
2817
2818 error = __split_vma(mm, vma, start, 0);
2819 if (error)
2820 return error;
2821 prev = vma;
2822 }
2823
2824 /* Does it split the last one? */
2825 last = find_vma(mm, end);
2826 if (last && end > last->vm_start) {
2827 int error = __split_vma(mm, last, end, 1);
2828 if (error)
2829 return error;
2830 }
2831 vma = prev ? prev->vm_next : mm->mmap;
2832
2833 if (unlikely(uf)) {
2834 /*
2835 * If userfaultfd_unmap_prep returns an error the vmas
2836 * will remain splitted, but userland will get a
2837 * highly unexpected error anyway. This is no
2838 * different than the case where the first of the two
2839 * __split_vma fails, but we don't undo the first
2840 * split, despite we could. This is unlikely enough
2841 * failure that it's not worth optimizing it for.
2842 */
2843 int error = userfaultfd_unmap_prep(vma, start, end, uf);
2844 if (error)
2845 return error;
2846 }
2847
2848 /*
2849 * unlock any mlock()ed ranges before detaching vmas
2850 */
2851 if (mm->locked_vm) {
2852 struct vm_area_struct *tmp = vma;
2853 while (tmp && tmp->vm_start < end) {
2854 if (tmp->vm_flags & VM_LOCKED) {
2855 mm->locked_vm -= vma_pages(tmp);
2856 munlock_vma_pages_all(tmp);
2857 }
2858
2859 tmp = tmp->vm_next;
2860 }
2861 }
2862
2863 /* Detach vmas from rbtree */
2864 if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
2865 downgrade = false;
2866
2867 if (downgrade)
2868 mmap_write_downgrade(mm);
2869
2870 unmap_region(mm, vma, prev, start, end);
2871
2872 /* Fix up all other VM information */
2873 remove_vma_list(mm, vma);
2874
2875 return downgrade ? 1 : 0;
2876}
2877
2878int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2879 struct list_head *uf)
2880{
2881 return __do_munmap(mm, start, len, uf, false);
2882}
2883
2884static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
2885{
2886 int ret;
2887 struct mm_struct *mm = current->mm;
2888 LIST_HEAD(uf);
2889
2890 if (mmap_write_lock_killable(mm))
2891 return -EINTR;
2892
2893 ret = __do_munmap(mm, start, len, &uf, downgrade);
2894 /*
2895 * Returning 1 indicates mmap_lock is downgraded.
2896 * But 1 is not legal return value of vm_munmap() and munmap(), reset
2897 * it to 0 before return.
2898 */
2899 if (ret == 1) {
2900 mmap_read_unlock(mm);
2901 ret = 0;
2902 } else
2903 mmap_write_unlock(mm);
2904
2905 userfaultfd_unmap_complete(mm, &uf);
2906 return ret;
2907}
2908
2909int vm_munmap(unsigned long start, size_t len)
2910{
2911 return __vm_munmap(start, len, false);
2912}
2913EXPORT_SYMBOL(vm_munmap);
2914
2915SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2916{
2917 addr = untagged_addr(addr);
2918 profile_munmap(addr);
2919 return __vm_munmap(addr, len, true);
2920}
2921
2922
2923/*
2924 * Emulation of deprecated remap_file_pages() syscall.
2925 */
2926SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2927 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2928{
2929
2930 struct mm_struct *mm = current->mm;
2931 struct vm_area_struct *vma;
2932 unsigned long populate = 0;
2933 unsigned long ret = -EINVAL;
2934 struct file *file;
2935
2936 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
2937 current->comm, current->pid);
2938
2939 if (prot)
2940 return ret;
2941 start = start & PAGE_MASK;
2942 size = size & PAGE_MASK;
2943
2944 if (start + size <= start)
2945 return ret;
2946
2947 /* Does pgoff wrap? */
2948 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2949 return ret;
2950
2951 if (mmap_write_lock_killable(mm))
2952 return -EINTR;
2953
2954 vma = find_vma(mm, start);
2955
2956 if (!vma || !(vma->vm_flags & VM_SHARED))
2957 goto out;
2958
2959 if (start < vma->vm_start)
2960 goto out;
2961
2962 if (start + size > vma->vm_end) {
2963 struct vm_area_struct *next;
2964
2965 for (next = vma->vm_next; next; next = next->vm_next) {
2966 /* hole between vmas ? */
2967 if (next->vm_start != next->vm_prev->vm_end)
2968 goto out;
2969
2970 if (next->vm_file != vma->vm_file)
2971 goto out;
2972
2973 if (next->vm_flags != vma->vm_flags)
2974 goto out;
2975
2976 if (start + size <= next->vm_end)
2977 break;
2978 }
2979
2980 if (!next)
2981 goto out;
2982 }
2983
2984 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2985 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2986 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2987
2988 flags &= MAP_NONBLOCK;
2989 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2990 if (vma->vm_flags & VM_LOCKED) {
2991 struct vm_area_struct *tmp;
2992 flags |= MAP_LOCKED;
2993
2994 /* drop PG_Mlocked flag for over-mapped range */
2995 for (tmp = vma; tmp->vm_start >= start + size;
2996 tmp = tmp->vm_next) {
2997 /*
2998 * Split pmd and munlock page on the border
2999 * of the range.
3000 */
3001 vma_adjust_trans_huge(tmp, start, start + size, 0);
3002
3003 munlock_vma_pages_range(tmp,
3004 max(tmp->vm_start, start),
3005 min(tmp->vm_end, start + size));
3006 }
3007 }
3008
3009 file = get_file(vma->vm_file);
3010 ret = do_mmap(vma->vm_file, start, size,
3011 prot, flags, pgoff, &populate, NULL);
3012 fput(file);
3013out:
3014 mmap_write_unlock(mm);
3015 if (populate)
3016 mm_populate(ret, populate);
3017 if (!IS_ERR_VALUE(ret))
3018 ret = 0;
3019 return ret;
3020}
3021
3022/*
3023 * this is really a simplified "do_mmap". it only handles
3024 * anonymous maps. eventually we may be able to do some
3025 * brk-specific accounting here.
3026 */
3027static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
3028{
3029 struct mm_struct *mm = current->mm;
3030 struct vm_area_struct *vma, *prev;
3031 struct rb_node **rb_link, *rb_parent;
3032 pgoff_t pgoff = addr >> PAGE_SHIFT;
3033 int error;
3034 unsigned long mapped_addr;
3035
3036 /* Until we need other flags, refuse anything except VM_EXEC. */
3037 if ((flags & (~VM_EXEC)) != 0)
3038 return -EINVAL;
3039 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3040
3041 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
3042 if (IS_ERR_VALUE(mapped_addr))
3043 return mapped_addr;
3044
3045 error = mlock_future_check(mm, mm->def_flags, len);
3046 if (error)
3047 return error;
3048
3049 /*
3050 * Clear old maps. this also does some error checking for us
3051 */
3052 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
3053 &rb_parent)) {
3054 if (do_munmap(mm, addr, len, uf))
3055 return -ENOMEM;
3056 }
3057
3058 /* Check against address space limits *after* clearing old maps... */
3059 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
3060 return -ENOMEM;
3061
3062 if (mm->map_count > sysctl_max_map_count)
3063 return -ENOMEM;
3064
3065 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
3066 return -ENOMEM;
3067
3068 /* Can we just expand an old private anonymous mapping? */
3069 vma = vma_merge(mm, prev, addr, addr + len, flags,
3070 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
3071 if (vma)
3072 goto out;
3073
3074 /*
3075 * create a vma struct for an anonymous mapping
3076 */
3077 vma = vm_area_alloc(mm);
3078 if (!vma) {
3079 vm_unacct_memory(len >> PAGE_SHIFT);
3080 return -ENOMEM;
3081 }
3082
3083 vma_set_anonymous(vma);
3084 vma->vm_start = addr;
3085 vma->vm_end = addr + len;
3086 vma->vm_pgoff = pgoff;
3087 vma->vm_flags = flags;
3088 vma->vm_page_prot = vm_get_page_prot(flags);
3089 vma_link(mm, vma, prev, rb_link, rb_parent);
3090out:
3091 perf_event_mmap(vma);
3092 mm->total_vm += len >> PAGE_SHIFT;
3093 mm->data_vm += len >> PAGE_SHIFT;
3094 if (flags & VM_LOCKED)
3095 mm->locked_vm += (len >> PAGE_SHIFT);
3096 vma->vm_flags |= VM_SOFTDIRTY;
3097 return 0;
3098}
3099
3100int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3101{
3102 struct mm_struct *mm = current->mm;
3103 unsigned long len;
3104 int ret;
3105 bool populate;
3106 LIST_HEAD(uf);
3107
3108 len = PAGE_ALIGN(request);
3109 if (len < request)
3110 return -ENOMEM;
3111 if (!len)
3112 return 0;
3113
3114 if (mmap_write_lock_killable(mm))
3115 return -EINTR;
3116
3117 ret = do_brk_flags(addr, len, flags, &uf);
3118 populate = ((mm->def_flags & VM_LOCKED) != 0);
3119 mmap_write_unlock(mm);
3120 userfaultfd_unmap_complete(mm, &uf);
3121 if (populate && !ret)
3122 mm_populate(addr, len);
3123 return ret;
3124}
3125EXPORT_SYMBOL(vm_brk_flags);
3126
3127int vm_brk(unsigned long addr, unsigned long len)
3128{
3129 return vm_brk_flags(addr, len, 0);
3130}
3131EXPORT_SYMBOL(vm_brk);
3132
3133/* Release all mmaps. */
3134void exit_mmap(struct mm_struct *mm)
3135{
3136 struct mmu_gather tlb;
3137 struct vm_area_struct *vma;
3138 unsigned long nr_accounted = 0;
3139
3140 /* mm's last user has gone, and its about to be pulled down */
3141 mmu_notifier_release(mm);
3142
3143 if (unlikely(mm_is_oom_victim(mm))) {
3144 /*
3145 * Manually reap the mm to free as much memory as possible.
3146 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
3147 * this mm from further consideration. Taking mm->mmap_lock for
3148 * write after setting MMF_OOM_SKIP will guarantee that the oom
3149 * reaper will not run on this mm again after mmap_lock is
3150 * dropped.
3151 *
3152 * Nothing can be holding mm->mmap_lock here and the above call
3153 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
3154 * __oom_reap_task_mm() will not block.
3155 *
3156 * This needs to be done before calling munlock_vma_pages_all(),
3157 * which clears VM_LOCKED, otherwise the oom reaper cannot
3158 * reliably test it.
3159 */
3160 (void)__oom_reap_task_mm(mm);
3161
3162 set_bit(MMF_OOM_SKIP, &mm->flags);
3163 mmap_write_lock(mm);
3164 mmap_write_unlock(mm);
3165 }
3166
3167 if (mm->locked_vm) {
3168 vma = mm->mmap;
3169 while (vma) {
3170 if (vma->vm_flags & VM_LOCKED)
3171 munlock_vma_pages_all(vma);
3172 vma = vma->vm_next;
3173 }
3174 }
3175
3176 arch_exit_mmap(mm);
3177
3178 vma = mm->mmap;
3179 if (!vma) /* Can happen if dup_mmap() received an OOM */
3180 return;
3181
3182 lru_add_drain();
3183 flush_cache_mm(mm);
3184 tlb_gather_mmu(&tlb, mm, 0, -1);
3185 /* update_hiwater_rss(mm) here? but nobody should be looking */
3186 /* Use -1 here to ensure all VMAs in the mm are unmapped */
3187 unmap_vmas(&tlb, vma, 0, -1);
3188 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
3189 tlb_finish_mmu(&tlb, 0, -1);
3190
3191 /*
3192 * Walk the list again, actually closing and freeing it,
3193 * with preemption enabled, without holding any MM locks.
3194 */
3195 while (vma) {
3196 if (vma->vm_flags & VM_ACCOUNT)
3197 nr_accounted += vma_pages(vma);
3198 vma = remove_vma(vma);
3199 cond_resched();
3200 }
3201 vm_unacct_memory(nr_accounted);
3202}
3203
3204/* Insert vm structure into process list sorted by address
3205 * and into the inode's i_mmap tree. If vm_file is non-NULL
3206 * then i_mmap_rwsem is taken here.
3207 */
3208int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3209{
3210 struct vm_area_struct *prev;
3211 struct rb_node **rb_link, *rb_parent;
3212
3213 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
3214 &prev, &rb_link, &rb_parent))
3215 return -ENOMEM;
3216 if ((vma->vm_flags & VM_ACCOUNT) &&
3217 security_vm_enough_memory_mm(mm, vma_pages(vma)))
3218 return -ENOMEM;
3219
3220 /*
3221 * The vm_pgoff of a purely anonymous vma should be irrelevant
3222 * until its first write fault, when page's anon_vma and index
3223 * are set. But now set the vm_pgoff it will almost certainly
3224 * end up with (unless mremap moves it elsewhere before that
3225 * first wfault), so /proc/pid/maps tells a consistent story.
3226 *
3227 * By setting it to reflect the virtual start address of the
3228 * vma, merges and splits can happen in a seamless way, just
3229 * using the existing file pgoff checks and manipulations.
3230 * Similarly in do_mmap and in do_brk.
3231 */
3232 if (vma_is_anonymous(vma)) {
3233 BUG_ON(vma->anon_vma);
3234 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3235 }
3236
3237 vma_link(mm, vma, prev, rb_link, rb_parent);
3238 return 0;
3239}
3240
3241/*
3242 * Copy the vma structure to a new location in the same mm,
3243 * prior to moving page table entries, to effect an mremap move.
3244 */
3245struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3246 unsigned long addr, unsigned long len, pgoff_t pgoff,
3247 bool *need_rmap_locks)
3248{
3249 struct vm_area_struct *vma = *vmap;
3250 unsigned long vma_start = vma->vm_start;
3251 struct mm_struct *mm = vma->vm_mm;
3252 struct vm_area_struct *new_vma, *prev;
3253 struct rb_node **rb_link, *rb_parent;
3254 bool faulted_in_anon_vma = true;
3255
3256 /*
3257 * If anonymous vma has not yet been faulted, update new pgoff
3258 * to match new location, to increase its chance of merging.
3259 */
3260 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3261 pgoff = addr >> PAGE_SHIFT;
3262 faulted_in_anon_vma = false;
3263 }
3264
3265 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3266 return NULL; /* should never get here */
3267 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3268 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3269 vma->vm_userfaultfd_ctx);
3270 if (new_vma) {
3271 /*
3272 * Source vma may have been merged into new_vma
3273 */
3274 if (unlikely(vma_start >= new_vma->vm_start &&
3275 vma_start < new_vma->vm_end)) {
3276 /*
3277 * The only way we can get a vma_merge with
3278 * self during an mremap is if the vma hasn't
3279 * been faulted in yet and we were allowed to
3280 * reset the dst vma->vm_pgoff to the
3281 * destination address of the mremap to allow
3282 * the merge to happen. mremap must change the
3283 * vm_pgoff linearity between src and dst vmas
3284 * (in turn preventing a vma_merge) to be
3285 * safe. It is only safe to keep the vm_pgoff
3286 * linear if there are no pages mapped yet.
3287 */
3288 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3289 *vmap = vma = new_vma;
3290 }
3291 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3292 } else {
3293 new_vma = vm_area_dup(vma);
3294 if (!new_vma)
3295 goto out;
3296 new_vma->vm_start = addr;
3297 new_vma->vm_end = addr + len;
3298 new_vma->vm_pgoff = pgoff;
3299 if (vma_dup_policy(vma, new_vma))
3300 goto out_free_vma;
3301 if (anon_vma_clone(new_vma, vma))
3302 goto out_free_mempol;
3303 if (new_vma->vm_file)
3304 get_file(new_vma->vm_file);
3305 if (new_vma->vm_ops && new_vma->vm_ops->open)
3306 new_vma->vm_ops->open(new_vma);
3307 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3308 *need_rmap_locks = false;
3309 }
3310 return new_vma;
3311
3312out_free_mempol:
3313 mpol_put(vma_policy(new_vma));
3314out_free_vma:
3315 vm_area_free(new_vma);
3316out:
3317 return NULL;
3318}
3319
3320/*
3321 * Return true if the calling process may expand its vm space by the passed
3322 * number of pages
3323 */
3324bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3325{
3326 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3327 return false;
3328
3329 if (is_data_mapping(flags) &&
3330 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3331 /* Workaround for Valgrind */
3332 if (rlimit(RLIMIT_DATA) == 0 &&
3333 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3334 return true;
3335
3336 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3337 current->comm, current->pid,
3338 (mm->data_vm + npages) << PAGE_SHIFT,
3339 rlimit(RLIMIT_DATA),
3340 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3341
3342 if (!ignore_rlimit_data)
3343 return false;
3344 }
3345
3346 return true;
3347}
3348
3349void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3350{
3351 mm->total_vm += npages;
3352
3353 if (is_exec_mapping(flags))
3354 mm->exec_vm += npages;
3355 else if (is_stack_mapping(flags))
3356 mm->stack_vm += npages;
3357 else if (is_data_mapping(flags))
3358 mm->data_vm += npages;
3359}
3360
3361static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3362
3363/*
3364 * Having a close hook prevents vma merging regardless of flags.
3365 */
3366static void special_mapping_close(struct vm_area_struct *vma)
3367{
3368}
3369
3370static const char *special_mapping_name(struct vm_area_struct *vma)
3371{
3372 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3373}
3374
3375static int special_mapping_mremap(struct vm_area_struct *new_vma)
3376{
3377 struct vm_special_mapping *sm = new_vma->vm_private_data;
3378
3379 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3380 return -EFAULT;
3381
3382 if (sm->mremap)
3383 return sm->mremap(sm, new_vma);
3384
3385 return 0;
3386}
3387
3388static const struct vm_operations_struct special_mapping_vmops = {
3389 .close = special_mapping_close,
3390 .fault = special_mapping_fault,
3391 .mremap = special_mapping_mremap,
3392 .name = special_mapping_name,
3393 /* vDSO code relies that VVAR can't be accessed remotely */
3394 .access = NULL,
3395};
3396
3397static const struct vm_operations_struct legacy_special_mapping_vmops = {
3398 .close = special_mapping_close,
3399 .fault = special_mapping_fault,
3400};
3401
3402static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3403{
3404 struct vm_area_struct *vma = vmf->vma;
3405 pgoff_t pgoff;
3406 struct page **pages;
3407
3408 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3409 pages = vma->vm_private_data;
3410 } else {
3411 struct vm_special_mapping *sm = vma->vm_private_data;
3412
3413 if (sm->fault)
3414 return sm->fault(sm, vmf->vma, vmf);
3415
3416 pages = sm->pages;
3417 }
3418
3419 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3420 pgoff--;
3421
3422 if (*pages) {
3423 struct page *page = *pages;
3424 get_page(page);
3425 vmf->page = page;
3426 return 0;
3427 }
3428
3429 return VM_FAULT_SIGBUS;
3430}
3431
3432static struct vm_area_struct *__install_special_mapping(
3433 struct mm_struct *mm,
3434 unsigned long addr, unsigned long len,
3435 unsigned long vm_flags, void *priv,
3436 const struct vm_operations_struct *ops)
3437{
3438 int ret;
3439 struct vm_area_struct *vma;
3440
3441 vma = vm_area_alloc(mm);
3442 if (unlikely(vma == NULL))
3443 return ERR_PTR(-ENOMEM);
3444
3445 vma->vm_start = addr;
3446 vma->vm_end = addr + len;
3447
3448 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3449 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3450
3451 vma->vm_ops = ops;
3452 vma->vm_private_data = priv;
3453
3454 ret = insert_vm_struct(mm, vma);
3455 if (ret)
3456 goto out;
3457
3458 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3459
3460 perf_event_mmap(vma);
3461
3462 return vma;
3463
3464out:
3465 vm_area_free(vma);
3466 return ERR_PTR(ret);
3467}
3468
3469bool vma_is_special_mapping(const struct vm_area_struct *vma,
3470 const struct vm_special_mapping *sm)
3471{
3472 return vma->vm_private_data == sm &&
3473 (vma->vm_ops == &special_mapping_vmops ||
3474 vma->vm_ops == &legacy_special_mapping_vmops);
3475}
3476
3477/*
3478 * Called with mm->mmap_lock held for writing.
3479 * Insert a new vma covering the given region, with the given flags.
3480 * Its pages are supplied by the given array of struct page *.
3481 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3482 * The region past the last page supplied will always produce SIGBUS.
3483 * The array pointer and the pages it points to are assumed to stay alive
3484 * for as long as this mapping might exist.
3485 */
3486struct vm_area_struct *_install_special_mapping(
3487 struct mm_struct *mm,
3488 unsigned long addr, unsigned long len,
3489 unsigned long vm_flags, const struct vm_special_mapping *spec)
3490{
3491 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3492 &special_mapping_vmops);
3493}
3494
3495int install_special_mapping(struct mm_struct *mm,
3496 unsigned long addr, unsigned long len,
3497 unsigned long vm_flags, struct page **pages)
3498{
3499 struct vm_area_struct *vma = __install_special_mapping(
3500 mm, addr, len, vm_flags, (void *)pages,
3501 &legacy_special_mapping_vmops);
3502
3503 return PTR_ERR_OR_ZERO(vma);
3504}
3505
3506static DEFINE_MUTEX(mm_all_locks_mutex);
3507
3508static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3509{
3510 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3511 /*
3512 * The LSB of head.next can't change from under us
3513 * because we hold the mm_all_locks_mutex.
3514 */
3515 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
3516 /*
3517 * We can safely modify head.next after taking the
3518 * anon_vma->root->rwsem. If some other vma in this mm shares
3519 * the same anon_vma we won't take it again.
3520 *
3521 * No need of atomic instructions here, head.next
3522 * can't change from under us thanks to the
3523 * anon_vma->root->rwsem.
3524 */
3525 if (__test_and_set_bit(0, (unsigned long *)
3526 &anon_vma->root->rb_root.rb_root.rb_node))
3527 BUG();
3528 }
3529}
3530
3531static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3532{
3533 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3534 /*
3535 * AS_MM_ALL_LOCKS can't change from under us because
3536 * we hold the mm_all_locks_mutex.
3537 *
3538 * Operations on ->flags have to be atomic because
3539 * even if AS_MM_ALL_LOCKS is stable thanks to the
3540 * mm_all_locks_mutex, there may be other cpus
3541 * changing other bitflags in parallel to us.
3542 */
3543 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3544 BUG();
3545 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
3546 }
3547}
3548
3549/*
3550 * This operation locks against the VM for all pte/vma/mm related
3551 * operations that could ever happen on a certain mm. This includes
3552 * vmtruncate, try_to_unmap, and all page faults.
3553 *
3554 * The caller must take the mmap_lock in write mode before calling
3555 * mm_take_all_locks(). The caller isn't allowed to release the
3556 * mmap_lock until mm_drop_all_locks() returns.
3557 *
3558 * mmap_lock in write mode is required in order to block all operations
3559 * that could modify pagetables and free pages without need of
3560 * altering the vma layout. It's also needed in write mode to avoid new
3561 * anon_vmas to be associated with existing vmas.
3562 *
3563 * A single task can't take more than one mm_take_all_locks() in a row
3564 * or it would deadlock.
3565 *
3566 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3567 * mapping->flags avoid to take the same lock twice, if more than one
3568 * vma in this mm is backed by the same anon_vma or address_space.
3569 *
3570 * We take locks in following order, accordingly to comment at beginning
3571 * of mm/rmap.c:
3572 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3573 * hugetlb mapping);
3574 * - all i_mmap_rwsem locks;
3575 * - all anon_vma->rwseml
3576 *
3577 * We can take all locks within these types randomly because the VM code
3578 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3579 * mm_all_locks_mutex.
3580 *
3581 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3582 * that may have to take thousand of locks.
3583 *
3584 * mm_take_all_locks() can fail if it's interrupted by signals.
3585 */
3586int mm_take_all_locks(struct mm_struct *mm)
3587{
3588 struct vm_area_struct *vma;
3589 struct anon_vma_chain *avc;
3590
3591 BUG_ON(mmap_read_trylock(mm));
3592
3593 mutex_lock(&mm_all_locks_mutex);
3594
3595 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3596 if (signal_pending(current))
3597 goto out_unlock;
3598 if (vma->vm_file && vma->vm_file->f_mapping &&
3599 is_vm_hugetlb_page(vma))
3600 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3601 }
3602
3603 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3604 if (signal_pending(current))
3605 goto out_unlock;
3606 if (vma->vm_file && vma->vm_file->f_mapping &&
3607 !is_vm_hugetlb_page(vma))
3608 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3609 }
3610
3611 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3612 if (signal_pending(current))
3613 goto out_unlock;
3614 if (vma->anon_vma)
3615 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3616 vm_lock_anon_vma(mm, avc->anon_vma);
3617 }
3618
3619 return 0;
3620
3621out_unlock:
3622 mm_drop_all_locks(mm);
3623 return -EINTR;
3624}
3625
3626static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3627{
3628 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3629 /*
3630 * The LSB of head.next can't change to 0 from under
3631 * us because we hold the mm_all_locks_mutex.
3632 *
3633 * We must however clear the bitflag before unlocking
3634 * the vma so the users using the anon_vma->rb_root will
3635 * never see our bitflag.
3636 *
3637 * No need of atomic instructions here, head.next
3638 * can't change from under us until we release the
3639 * anon_vma->root->rwsem.
3640 */
3641 if (!__test_and_clear_bit(0, (unsigned long *)
3642 &anon_vma->root->rb_root.rb_root.rb_node))
3643 BUG();
3644 anon_vma_unlock_write(anon_vma);
3645 }
3646}
3647
3648static void vm_unlock_mapping(struct address_space *mapping)
3649{
3650 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3651 /*
3652 * AS_MM_ALL_LOCKS can't change to 0 from under us
3653 * because we hold the mm_all_locks_mutex.
3654 */
3655 i_mmap_unlock_write(mapping);
3656 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3657 &mapping->flags))
3658 BUG();
3659 }
3660}
3661
3662/*
3663 * The mmap_lock cannot be released by the caller until
3664 * mm_drop_all_locks() returns.
3665 */
3666void mm_drop_all_locks(struct mm_struct *mm)
3667{
3668 struct vm_area_struct *vma;
3669 struct anon_vma_chain *avc;
3670
3671 BUG_ON(mmap_read_trylock(mm));
3672 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3673
3674 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3675 if (vma->anon_vma)
3676 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3677 vm_unlock_anon_vma(avc->anon_vma);
3678 if (vma->vm_file && vma->vm_file->f_mapping)
3679 vm_unlock_mapping(vma->vm_file->f_mapping);
3680 }
3681
3682 mutex_unlock(&mm_all_locks_mutex);
3683}
3684
3685/*
3686 * initialise the percpu counter for VM
3687 */
3688void __init mmap_init(void)
3689{
3690 int ret;
3691
3692 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3693 VM_BUG_ON(ret);
3694}
3695
3696/*
3697 * Initialise sysctl_user_reserve_kbytes.
3698 *
3699 * This is intended to prevent a user from starting a single memory hogging
3700 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3701 * mode.
3702 *
3703 * The default value is min(3% of free memory, 128MB)
3704 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3705 */
3706static int init_user_reserve(void)
3707{
3708 unsigned long free_kbytes;
3709
3710 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3711
3712 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3713 return 0;
3714}
3715subsys_initcall(init_user_reserve);
3716
3717/*
3718 * Initialise sysctl_admin_reserve_kbytes.
3719 *
3720 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3721 * to log in and kill a memory hogging process.
3722 *
3723 * Systems with more than 256MB will reserve 8MB, enough to recover
3724 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3725 * only reserve 3% of free pages by default.
3726 */
3727static int init_admin_reserve(void)
3728{
3729 unsigned long free_kbytes;
3730
3731 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3732
3733 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3734 return 0;
3735}
3736subsys_initcall(init_admin_reserve);
3737
3738/*
3739 * Reinititalise user and admin reserves if memory is added or removed.
3740 *
3741 * The default user reserve max is 128MB, and the default max for the
3742 * admin reserve is 8MB. These are usually, but not always, enough to
3743 * enable recovery from a memory hogging process using login/sshd, a shell,
3744 * and tools like top. It may make sense to increase or even disable the
3745 * reserve depending on the existence of swap or variations in the recovery
3746 * tools. So, the admin may have changed them.
3747 *
3748 * If memory is added and the reserves have been eliminated or increased above
3749 * the default max, then we'll trust the admin.
3750 *
3751 * If memory is removed and there isn't enough free memory, then we
3752 * need to reset the reserves.
3753 *
3754 * Otherwise keep the reserve set by the admin.
3755 */
3756static int reserve_mem_notifier(struct notifier_block *nb,
3757 unsigned long action, void *data)
3758{
3759 unsigned long tmp, free_kbytes;
3760
3761 switch (action) {
3762 case MEM_ONLINE:
3763 /* Default max is 128MB. Leave alone if modified by operator. */
3764 tmp = sysctl_user_reserve_kbytes;
3765 if (0 < tmp && tmp < (1UL << 17))
3766 init_user_reserve();
3767
3768 /* Default max is 8MB. Leave alone if modified by operator. */
3769 tmp = sysctl_admin_reserve_kbytes;
3770 if (0 < tmp && tmp < (1UL << 13))
3771 init_admin_reserve();
3772
3773 break;
3774 case MEM_OFFLINE:
3775 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3776
3777 if (sysctl_user_reserve_kbytes > free_kbytes) {
3778 init_user_reserve();
3779 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3780 sysctl_user_reserve_kbytes);
3781 }
3782
3783 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3784 init_admin_reserve();
3785 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3786 sysctl_admin_reserve_kbytes);
3787 }
3788 break;
3789 default:
3790 break;
3791 }
3792 return NOTIFY_OK;
3793}
3794
3795static struct notifier_block reserve_mem_nb = {
3796 .notifier_call = reserve_mem_notifier,
3797};
3798
3799static int __meminit init_reserve_notifier(void)
3800{
3801 if (register_hotmemory_notifier(&reserve_mem_nb))
3802 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3803
3804 return 0;
3805}
3806subsys_initcall(init_reserve_notifier);