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1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/mm.h>
3#include <linux/slab.h>
4#include <linux/string.h>
5#include <linux/compiler.h>
6#include <linux/export.h>
7#include <linux/err.h>
8#include <linux/sched.h>
9#include <linux/sched/mm.h>
10#include <linux/sched/signal.h>
11#include <linux/sched/task_stack.h>
12#include <linux/security.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/mman.h>
16#include <linux/hugetlb.h>
17#include <linux/vmalloc.h>
18#include <linux/userfaultfd_k.h>
19#include <linux/elf.h>
20#include <linux/elf-randomize.h>
21#include <linux/personality.h>
22#include <linux/random.h>
23#include <linux/processor.h>
24#include <linux/sizes.h>
25#include <linux/compat.h>
26
27#include <linux/uaccess.h>
28
29#include "internal.h"
30#include "swap.h"
31
32/**
33 * kfree_const - conditionally free memory
34 * @x: pointer to the memory
35 *
36 * Function calls kfree only if @x is not in .rodata section.
37 */
38void kfree_const(const void *x)
39{
40 if (!is_kernel_rodata((unsigned long)x))
41 kfree(x);
42}
43EXPORT_SYMBOL(kfree_const);
44
45/**
46 * kstrdup - allocate space for and copy an existing string
47 * @s: the string to duplicate
48 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
49 *
50 * Return: newly allocated copy of @s or %NULL in case of error
51 */
52noinline
53char *kstrdup(const char *s, gfp_t gfp)
54{
55 size_t len;
56 char *buf;
57
58 if (!s)
59 return NULL;
60
61 len = strlen(s) + 1;
62 buf = kmalloc_track_caller(len, gfp);
63 if (buf)
64 memcpy(buf, s, len);
65 return buf;
66}
67EXPORT_SYMBOL(kstrdup);
68
69/**
70 * kstrdup_const - conditionally duplicate an existing const string
71 * @s: the string to duplicate
72 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
73 *
74 * Note: Strings allocated by kstrdup_const should be freed by kfree_const and
75 * must not be passed to krealloc().
76 *
77 * Return: source string if it is in .rodata section otherwise
78 * fallback to kstrdup.
79 */
80const char *kstrdup_const(const char *s, gfp_t gfp)
81{
82 if (is_kernel_rodata((unsigned long)s))
83 return s;
84
85 return kstrdup(s, gfp);
86}
87EXPORT_SYMBOL(kstrdup_const);
88
89/**
90 * kstrndup - allocate space for and copy an existing string
91 * @s: the string to duplicate
92 * @max: read at most @max chars from @s
93 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
94 *
95 * Note: Use kmemdup_nul() instead if the size is known exactly.
96 *
97 * Return: newly allocated copy of @s or %NULL in case of error
98 */
99char *kstrndup(const char *s, size_t max, gfp_t gfp)
100{
101 size_t len;
102 char *buf;
103
104 if (!s)
105 return NULL;
106
107 len = strnlen(s, max);
108 buf = kmalloc_track_caller(len+1, gfp);
109 if (buf) {
110 memcpy(buf, s, len);
111 buf[len] = '\0';
112 }
113 return buf;
114}
115EXPORT_SYMBOL(kstrndup);
116
117/**
118 * kmemdup - duplicate region of memory
119 *
120 * @src: memory region to duplicate
121 * @len: memory region length
122 * @gfp: GFP mask to use
123 *
124 * Return: newly allocated copy of @src or %NULL in case of error,
125 * result is physically contiguous. Use kfree() to free.
126 */
127void *kmemdup(const void *src, size_t len, gfp_t gfp)
128{
129 void *p;
130
131 p = kmalloc_track_caller(len, gfp);
132 if (p)
133 memcpy(p, src, len);
134 return p;
135}
136EXPORT_SYMBOL(kmemdup);
137
138/**
139 * kvmemdup - duplicate region of memory
140 *
141 * @src: memory region to duplicate
142 * @len: memory region length
143 * @gfp: GFP mask to use
144 *
145 * Return: newly allocated copy of @src or %NULL in case of error,
146 * result may be not physically contiguous. Use kvfree() to free.
147 */
148void *kvmemdup(const void *src, size_t len, gfp_t gfp)
149{
150 void *p;
151
152 p = kvmalloc(len, gfp);
153 if (p)
154 memcpy(p, src, len);
155 return p;
156}
157EXPORT_SYMBOL(kvmemdup);
158
159/**
160 * kmemdup_nul - Create a NUL-terminated string from unterminated data
161 * @s: The data to stringify
162 * @len: The size of the data
163 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
164 *
165 * Return: newly allocated copy of @s with NUL-termination or %NULL in
166 * case of error
167 */
168char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
169{
170 char *buf;
171
172 if (!s)
173 return NULL;
174
175 buf = kmalloc_track_caller(len + 1, gfp);
176 if (buf) {
177 memcpy(buf, s, len);
178 buf[len] = '\0';
179 }
180 return buf;
181}
182EXPORT_SYMBOL(kmemdup_nul);
183
184/**
185 * memdup_user - duplicate memory region from user space
186 *
187 * @src: source address in user space
188 * @len: number of bytes to copy
189 *
190 * Return: an ERR_PTR() on failure. Result is physically
191 * contiguous, to be freed by kfree().
192 */
193void *memdup_user(const void __user *src, size_t len)
194{
195 void *p;
196
197 p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
198 if (!p)
199 return ERR_PTR(-ENOMEM);
200
201 if (copy_from_user(p, src, len)) {
202 kfree(p);
203 return ERR_PTR(-EFAULT);
204 }
205
206 return p;
207}
208EXPORT_SYMBOL(memdup_user);
209
210/**
211 * vmemdup_user - duplicate memory region from user space
212 *
213 * @src: source address in user space
214 * @len: number of bytes to copy
215 *
216 * Return: an ERR_PTR() on failure. Result may be not
217 * physically contiguous. Use kvfree() to free.
218 */
219void *vmemdup_user(const void __user *src, size_t len)
220{
221 void *p;
222
223 p = kvmalloc(len, GFP_USER);
224 if (!p)
225 return ERR_PTR(-ENOMEM);
226
227 if (copy_from_user(p, src, len)) {
228 kvfree(p);
229 return ERR_PTR(-EFAULT);
230 }
231
232 return p;
233}
234EXPORT_SYMBOL(vmemdup_user);
235
236/**
237 * strndup_user - duplicate an existing string from user space
238 * @s: The string to duplicate
239 * @n: Maximum number of bytes to copy, including the trailing NUL.
240 *
241 * Return: newly allocated copy of @s or an ERR_PTR() in case of error
242 */
243char *strndup_user(const char __user *s, long n)
244{
245 char *p;
246 long length;
247
248 length = strnlen_user(s, n);
249
250 if (!length)
251 return ERR_PTR(-EFAULT);
252
253 if (length > n)
254 return ERR_PTR(-EINVAL);
255
256 p = memdup_user(s, length);
257
258 if (IS_ERR(p))
259 return p;
260
261 p[length - 1] = '\0';
262
263 return p;
264}
265EXPORT_SYMBOL(strndup_user);
266
267/**
268 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
269 *
270 * @src: source address in user space
271 * @len: number of bytes to copy
272 *
273 * Return: an ERR_PTR() on failure.
274 */
275void *memdup_user_nul(const void __user *src, size_t len)
276{
277 char *p;
278
279 /*
280 * Always use GFP_KERNEL, since copy_from_user() can sleep and
281 * cause pagefault, which makes it pointless to use GFP_NOFS
282 * or GFP_ATOMIC.
283 */
284 p = kmalloc_track_caller(len + 1, GFP_KERNEL);
285 if (!p)
286 return ERR_PTR(-ENOMEM);
287
288 if (copy_from_user(p, src, len)) {
289 kfree(p);
290 return ERR_PTR(-EFAULT);
291 }
292 p[len] = '\0';
293
294 return p;
295}
296EXPORT_SYMBOL(memdup_user_nul);
297
298/* Check if the vma is being used as a stack by this task */
299int vma_is_stack_for_current(struct vm_area_struct *vma)
300{
301 struct task_struct * __maybe_unused t = current;
302
303 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
304}
305
306/*
307 * Change backing file, only valid to use during initial VMA setup.
308 */
309void vma_set_file(struct vm_area_struct *vma, struct file *file)
310{
311 /* Changing an anonymous vma with this is illegal */
312 get_file(file);
313 swap(vma->vm_file, file);
314 fput(file);
315}
316EXPORT_SYMBOL(vma_set_file);
317
318#ifndef STACK_RND_MASK
319#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
320#endif
321
322unsigned long randomize_stack_top(unsigned long stack_top)
323{
324 unsigned long random_variable = 0;
325
326 if (current->flags & PF_RANDOMIZE) {
327 random_variable = get_random_long();
328 random_variable &= STACK_RND_MASK;
329 random_variable <<= PAGE_SHIFT;
330 }
331#ifdef CONFIG_STACK_GROWSUP
332 return PAGE_ALIGN(stack_top) + random_variable;
333#else
334 return PAGE_ALIGN(stack_top) - random_variable;
335#endif
336}
337
338/**
339 * randomize_page - Generate a random, page aligned address
340 * @start: The smallest acceptable address the caller will take.
341 * @range: The size of the area, starting at @start, within which the
342 * random address must fall.
343 *
344 * If @start + @range would overflow, @range is capped.
345 *
346 * NOTE: Historical use of randomize_range, which this replaces, presumed that
347 * @start was already page aligned. We now align it regardless.
348 *
349 * Return: A page aligned address within [start, start + range). On error,
350 * @start is returned.
351 */
352unsigned long randomize_page(unsigned long start, unsigned long range)
353{
354 if (!PAGE_ALIGNED(start)) {
355 range -= PAGE_ALIGN(start) - start;
356 start = PAGE_ALIGN(start);
357 }
358
359 if (start > ULONG_MAX - range)
360 range = ULONG_MAX - start;
361
362 range >>= PAGE_SHIFT;
363
364 if (range == 0)
365 return start;
366
367 return start + (get_random_long() % range << PAGE_SHIFT);
368}
369
370#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
371unsigned long __weak arch_randomize_brk(struct mm_struct *mm)
372{
373 /* Is the current task 32bit ? */
374 if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
375 return randomize_page(mm->brk, SZ_32M);
376
377 return randomize_page(mm->brk, SZ_1G);
378}
379
380unsigned long arch_mmap_rnd(void)
381{
382 unsigned long rnd;
383
384#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
385 if (is_compat_task())
386 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
387 else
388#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
389 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
390
391 return rnd << PAGE_SHIFT;
392}
393
394static int mmap_is_legacy(struct rlimit *rlim_stack)
395{
396 if (current->personality & ADDR_COMPAT_LAYOUT)
397 return 1;
398
399 /* On parisc the stack always grows up - so a unlimited stack should
400 * not be an indicator to use the legacy memory layout. */
401 if (rlim_stack->rlim_cur == RLIM_INFINITY &&
402 !IS_ENABLED(CONFIG_STACK_GROWSUP))
403 return 1;
404
405 return sysctl_legacy_va_layout;
406}
407
408/*
409 * Leave enough space between the mmap area and the stack to honour ulimit in
410 * the face of randomisation.
411 */
412#define MIN_GAP (SZ_128M)
413#define MAX_GAP (STACK_TOP / 6 * 5)
414
415static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
416{
417#ifdef CONFIG_STACK_GROWSUP
418 /*
419 * For an upwards growing stack the calculation is much simpler.
420 * Memory for the maximum stack size is reserved at the top of the
421 * task. mmap_base starts directly below the stack and grows
422 * downwards.
423 */
424 return PAGE_ALIGN_DOWN(mmap_upper_limit(rlim_stack) - rnd);
425#else
426 unsigned long gap = rlim_stack->rlim_cur;
427 unsigned long pad = stack_guard_gap;
428
429 /* Account for stack randomization if necessary */
430 if (current->flags & PF_RANDOMIZE)
431 pad += (STACK_RND_MASK << PAGE_SHIFT);
432
433 /* Values close to RLIM_INFINITY can overflow. */
434 if (gap + pad > gap)
435 gap += pad;
436
437 if (gap < MIN_GAP)
438 gap = MIN_GAP;
439 else if (gap > MAX_GAP)
440 gap = MAX_GAP;
441
442 return PAGE_ALIGN(STACK_TOP - gap - rnd);
443#endif
444}
445
446void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
447{
448 unsigned long random_factor = 0UL;
449
450 if (current->flags & PF_RANDOMIZE)
451 random_factor = arch_mmap_rnd();
452
453 if (mmap_is_legacy(rlim_stack)) {
454 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
455 mm->get_unmapped_area = arch_get_unmapped_area;
456 } else {
457 mm->mmap_base = mmap_base(random_factor, rlim_stack);
458 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
459 }
460}
461#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
462void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
463{
464 mm->mmap_base = TASK_UNMAPPED_BASE;
465 mm->get_unmapped_area = arch_get_unmapped_area;
466}
467#endif
468
469/**
470 * __account_locked_vm - account locked pages to an mm's locked_vm
471 * @mm: mm to account against
472 * @pages: number of pages to account
473 * @inc: %true if @pages should be considered positive, %false if not
474 * @task: task used to check RLIMIT_MEMLOCK
475 * @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
476 *
477 * Assumes @task and @mm are valid (i.e. at least one reference on each), and
478 * that mmap_lock is held as writer.
479 *
480 * Return:
481 * * 0 on success
482 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
483 */
484int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
485 struct task_struct *task, bool bypass_rlim)
486{
487 unsigned long locked_vm, limit;
488 int ret = 0;
489
490 mmap_assert_write_locked(mm);
491
492 locked_vm = mm->locked_vm;
493 if (inc) {
494 if (!bypass_rlim) {
495 limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
496 if (locked_vm + pages > limit)
497 ret = -ENOMEM;
498 }
499 if (!ret)
500 mm->locked_vm = locked_vm + pages;
501 } else {
502 WARN_ON_ONCE(pages > locked_vm);
503 mm->locked_vm = locked_vm - pages;
504 }
505
506 pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
507 (void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
508 locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
509 ret ? " - exceeded" : "");
510
511 return ret;
512}
513EXPORT_SYMBOL_GPL(__account_locked_vm);
514
515/**
516 * account_locked_vm - account locked pages to an mm's locked_vm
517 * @mm: mm to account against, may be NULL
518 * @pages: number of pages to account
519 * @inc: %true if @pages should be considered positive, %false if not
520 *
521 * Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
522 *
523 * Return:
524 * * 0 on success, or if mm is NULL
525 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
526 */
527int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
528{
529 int ret;
530
531 if (pages == 0 || !mm)
532 return 0;
533
534 mmap_write_lock(mm);
535 ret = __account_locked_vm(mm, pages, inc, current,
536 capable(CAP_IPC_LOCK));
537 mmap_write_unlock(mm);
538
539 return ret;
540}
541EXPORT_SYMBOL_GPL(account_locked_vm);
542
543unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
544 unsigned long len, unsigned long prot,
545 unsigned long flag, unsigned long pgoff)
546{
547 unsigned long ret;
548 struct mm_struct *mm = current->mm;
549 unsigned long populate;
550 LIST_HEAD(uf);
551
552 ret = security_mmap_file(file, prot, flag);
553 if (!ret) {
554 if (mmap_write_lock_killable(mm))
555 return -EINTR;
556 ret = do_mmap(file, addr, len, prot, flag, 0, pgoff, &populate,
557 &uf);
558 mmap_write_unlock(mm);
559 userfaultfd_unmap_complete(mm, &uf);
560 if (populate)
561 mm_populate(ret, populate);
562 }
563 return ret;
564}
565
566unsigned long vm_mmap(struct file *file, unsigned long addr,
567 unsigned long len, unsigned long prot,
568 unsigned long flag, unsigned long offset)
569{
570 if (unlikely(offset + PAGE_ALIGN(len) < offset))
571 return -EINVAL;
572 if (unlikely(offset_in_page(offset)))
573 return -EINVAL;
574
575 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
576}
577EXPORT_SYMBOL(vm_mmap);
578
579/**
580 * kvmalloc_node - attempt to allocate physically contiguous memory, but upon
581 * failure, fall back to non-contiguous (vmalloc) allocation.
582 * @size: size of the request.
583 * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
584 * @node: numa node to allocate from
585 *
586 * Uses kmalloc to get the memory but if the allocation fails then falls back
587 * to the vmalloc allocator. Use kvfree for freeing the memory.
588 *
589 * GFP_NOWAIT and GFP_ATOMIC are not supported, neither is the __GFP_NORETRY modifier.
590 * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
591 * preferable to the vmalloc fallback, due to visible performance drawbacks.
592 *
593 * Return: pointer to the allocated memory of %NULL in case of failure
594 */
595void *kvmalloc_node(size_t size, gfp_t flags, int node)
596{
597 gfp_t kmalloc_flags = flags;
598 void *ret;
599
600 /*
601 * We want to attempt a large physically contiguous block first because
602 * it is less likely to fragment multiple larger blocks and therefore
603 * contribute to a long term fragmentation less than vmalloc fallback.
604 * However make sure that larger requests are not too disruptive - no
605 * OOM killer and no allocation failure warnings as we have a fallback.
606 */
607 if (size > PAGE_SIZE) {
608 kmalloc_flags |= __GFP_NOWARN;
609
610 if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
611 kmalloc_flags |= __GFP_NORETRY;
612
613 /* nofail semantic is implemented by the vmalloc fallback */
614 kmalloc_flags &= ~__GFP_NOFAIL;
615 }
616
617 ret = kmalloc_node(size, kmalloc_flags, node);
618
619 /*
620 * It doesn't really make sense to fallback to vmalloc for sub page
621 * requests
622 */
623 if (ret || size <= PAGE_SIZE)
624 return ret;
625
626 /* non-sleeping allocations are not supported by vmalloc */
627 if (!gfpflags_allow_blocking(flags))
628 return NULL;
629
630 /* Don't even allow crazy sizes */
631 if (unlikely(size > INT_MAX)) {
632 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
633 return NULL;
634 }
635
636 /*
637 * kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
638 * since the callers already cannot assume anything
639 * about the resulting pointer, and cannot play
640 * protection games.
641 */
642 return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
643 flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
644 node, __builtin_return_address(0));
645}
646EXPORT_SYMBOL(kvmalloc_node);
647
648/**
649 * kvfree() - Free memory.
650 * @addr: Pointer to allocated memory.
651 *
652 * kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
653 * It is slightly more efficient to use kfree() or vfree() if you are certain
654 * that you know which one to use.
655 *
656 * Context: Either preemptible task context or not-NMI interrupt.
657 */
658void kvfree(const void *addr)
659{
660 if (is_vmalloc_addr(addr))
661 vfree(addr);
662 else
663 kfree(addr);
664}
665EXPORT_SYMBOL(kvfree);
666
667/**
668 * kvfree_sensitive - Free a data object containing sensitive information.
669 * @addr: address of the data object to be freed.
670 * @len: length of the data object.
671 *
672 * Use the special memzero_explicit() function to clear the content of a
673 * kvmalloc'ed object containing sensitive data to make sure that the
674 * compiler won't optimize out the data clearing.
675 */
676void kvfree_sensitive(const void *addr, size_t len)
677{
678 if (likely(!ZERO_OR_NULL_PTR(addr))) {
679 memzero_explicit((void *)addr, len);
680 kvfree(addr);
681 }
682}
683EXPORT_SYMBOL(kvfree_sensitive);
684
685void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
686{
687 void *newp;
688
689 if (oldsize >= newsize)
690 return (void *)p;
691 newp = kvmalloc(newsize, flags);
692 if (!newp)
693 return NULL;
694 memcpy(newp, p, oldsize);
695 kvfree(p);
696 return newp;
697}
698EXPORT_SYMBOL(kvrealloc);
699
700/**
701 * __vmalloc_array - allocate memory for a virtually contiguous array.
702 * @n: number of elements.
703 * @size: element size.
704 * @flags: the type of memory to allocate (see kmalloc).
705 */
706void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
707{
708 size_t bytes;
709
710 if (unlikely(check_mul_overflow(n, size, &bytes)))
711 return NULL;
712 return __vmalloc(bytes, flags);
713}
714EXPORT_SYMBOL(__vmalloc_array);
715
716/**
717 * vmalloc_array - allocate memory for a virtually contiguous array.
718 * @n: number of elements.
719 * @size: element size.
720 */
721void *vmalloc_array(size_t n, size_t size)
722{
723 return __vmalloc_array(n, size, GFP_KERNEL);
724}
725EXPORT_SYMBOL(vmalloc_array);
726
727/**
728 * __vcalloc - allocate and zero memory for a virtually contiguous array.
729 * @n: number of elements.
730 * @size: element size.
731 * @flags: the type of memory to allocate (see kmalloc).
732 */
733void *__vcalloc(size_t n, size_t size, gfp_t flags)
734{
735 return __vmalloc_array(n, size, flags | __GFP_ZERO);
736}
737EXPORT_SYMBOL(__vcalloc);
738
739/**
740 * vcalloc - allocate and zero memory for a virtually contiguous array.
741 * @n: number of elements.
742 * @size: element size.
743 */
744void *vcalloc(size_t n, size_t size)
745{
746 return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
747}
748EXPORT_SYMBOL(vcalloc);
749
750struct anon_vma *folio_anon_vma(struct folio *folio)
751{
752 unsigned long mapping = (unsigned long)folio->mapping;
753
754 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
755 return NULL;
756 return (void *)(mapping - PAGE_MAPPING_ANON);
757}
758
759/**
760 * folio_mapping - Find the mapping where this folio is stored.
761 * @folio: The folio.
762 *
763 * For folios which are in the page cache, return the mapping that this
764 * page belongs to. Folios in the swap cache return the swap mapping
765 * this page is stored in (which is different from the mapping for the
766 * swap file or swap device where the data is stored).
767 *
768 * You can call this for folios which aren't in the swap cache or page
769 * cache and it will return NULL.
770 */
771struct address_space *folio_mapping(struct folio *folio)
772{
773 struct address_space *mapping;
774
775 /* This happens if someone calls flush_dcache_page on slab page */
776 if (unlikely(folio_test_slab(folio)))
777 return NULL;
778
779 if (unlikely(folio_test_swapcache(folio)))
780 return swap_address_space(folio->swap);
781
782 mapping = folio->mapping;
783 if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
784 return NULL;
785
786 return mapping;
787}
788EXPORT_SYMBOL(folio_mapping);
789
790/**
791 * folio_copy - Copy the contents of one folio to another.
792 * @dst: Folio to copy to.
793 * @src: Folio to copy from.
794 *
795 * The bytes in the folio represented by @src are copied to @dst.
796 * Assumes the caller has validated that @dst is at least as large as @src.
797 * Can be called in atomic context for order-0 folios, but if the folio is
798 * larger, it may sleep.
799 */
800void folio_copy(struct folio *dst, struct folio *src)
801{
802 long i = 0;
803 long nr = folio_nr_pages(src);
804
805 for (;;) {
806 copy_highpage(folio_page(dst, i), folio_page(src, i));
807 if (++i == nr)
808 break;
809 cond_resched();
810 }
811}
812EXPORT_SYMBOL(folio_copy);
813
814int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
815int sysctl_overcommit_ratio __read_mostly = 50;
816unsigned long sysctl_overcommit_kbytes __read_mostly;
817int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
818unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
819unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
820
821int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer,
822 size_t *lenp, loff_t *ppos)
823{
824 int ret;
825
826 ret = proc_dointvec(table, write, buffer, lenp, ppos);
827 if (ret == 0 && write)
828 sysctl_overcommit_kbytes = 0;
829 return ret;
830}
831
832static void sync_overcommit_as(struct work_struct *dummy)
833{
834 percpu_counter_sync(&vm_committed_as);
835}
836
837int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer,
838 size_t *lenp, loff_t *ppos)
839{
840 struct ctl_table t;
841 int new_policy = -1;
842 int ret;
843
844 /*
845 * The deviation of sync_overcommit_as could be big with loose policy
846 * like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to
847 * strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply
848 * with the strict "NEVER", and to avoid possible race condition (even
849 * though user usually won't too frequently do the switching to policy
850 * OVERCOMMIT_NEVER), the switch is done in the following order:
851 * 1. changing the batch
852 * 2. sync percpu count on each CPU
853 * 3. switch the policy
854 */
855 if (write) {
856 t = *table;
857 t.data = &new_policy;
858 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
859 if (ret || new_policy == -1)
860 return ret;
861
862 mm_compute_batch(new_policy);
863 if (new_policy == OVERCOMMIT_NEVER)
864 schedule_on_each_cpu(sync_overcommit_as);
865 sysctl_overcommit_memory = new_policy;
866 } else {
867 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
868 }
869
870 return ret;
871}
872
873int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer,
874 size_t *lenp, loff_t *ppos)
875{
876 int ret;
877
878 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
879 if (ret == 0 && write)
880 sysctl_overcommit_ratio = 0;
881 return ret;
882}
883
884/*
885 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
886 */
887unsigned long vm_commit_limit(void)
888{
889 unsigned long allowed;
890
891 if (sysctl_overcommit_kbytes)
892 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
893 else
894 allowed = ((totalram_pages() - hugetlb_total_pages())
895 * sysctl_overcommit_ratio / 100);
896 allowed += total_swap_pages;
897
898 return allowed;
899}
900
901/*
902 * Make sure vm_committed_as in one cacheline and not cacheline shared with
903 * other variables. It can be updated by several CPUs frequently.
904 */
905struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
906
907/*
908 * The global memory commitment made in the system can be a metric
909 * that can be used to drive ballooning decisions when Linux is hosted
910 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
911 * balancing memory across competing virtual machines that are hosted.
912 * Several metrics drive this policy engine including the guest reported
913 * memory commitment.
914 *
915 * The time cost of this is very low for small platforms, and for big
916 * platform like a 2S/36C/72T Skylake server, in worst case where
917 * vm_committed_as's spinlock is under severe contention, the time cost
918 * could be about 30~40 microseconds.
919 */
920unsigned long vm_memory_committed(void)
921{
922 return percpu_counter_sum_positive(&vm_committed_as);
923}
924EXPORT_SYMBOL_GPL(vm_memory_committed);
925
926/*
927 * Check that a process has enough memory to allocate a new virtual
928 * mapping. 0 means there is enough memory for the allocation to
929 * succeed and -ENOMEM implies there is not.
930 *
931 * We currently support three overcommit policies, which are set via the
932 * vm.overcommit_memory sysctl. See Documentation/mm/overcommit-accounting.rst
933 *
934 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
935 * Additional code 2002 Jul 20 by Robert Love.
936 *
937 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
938 *
939 * Note this is a helper function intended to be used by LSMs which
940 * wish to use this logic.
941 */
942int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
943{
944 long allowed;
945
946 vm_acct_memory(pages);
947
948 /*
949 * Sometimes we want to use more memory than we have
950 */
951 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
952 return 0;
953
954 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
955 if (pages > totalram_pages() + total_swap_pages)
956 goto error;
957 return 0;
958 }
959
960 allowed = vm_commit_limit();
961 /*
962 * Reserve some for root
963 */
964 if (!cap_sys_admin)
965 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
966
967 /*
968 * Don't let a single process grow so big a user can't recover
969 */
970 if (mm) {
971 long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
972
973 allowed -= min_t(long, mm->total_vm / 32, reserve);
974 }
975
976 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
977 return 0;
978error:
979 pr_warn_ratelimited("%s: pid: %d, comm: %s, not enough memory for the allocation\n",
980 __func__, current->pid, current->comm);
981 vm_unacct_memory(pages);
982
983 return -ENOMEM;
984}
985
986/**
987 * get_cmdline() - copy the cmdline value to a buffer.
988 * @task: the task whose cmdline value to copy.
989 * @buffer: the buffer to copy to.
990 * @buflen: the length of the buffer. Larger cmdline values are truncated
991 * to this length.
992 *
993 * Return: the size of the cmdline field copied. Note that the copy does
994 * not guarantee an ending NULL byte.
995 */
996int get_cmdline(struct task_struct *task, char *buffer, int buflen)
997{
998 int res = 0;
999 unsigned int len;
1000 struct mm_struct *mm = get_task_mm(task);
1001 unsigned long arg_start, arg_end, env_start, env_end;
1002 if (!mm)
1003 goto out;
1004 if (!mm->arg_end)
1005 goto out_mm; /* Shh! No looking before we're done */
1006
1007 spin_lock(&mm->arg_lock);
1008 arg_start = mm->arg_start;
1009 arg_end = mm->arg_end;
1010 env_start = mm->env_start;
1011 env_end = mm->env_end;
1012 spin_unlock(&mm->arg_lock);
1013
1014 len = arg_end - arg_start;
1015
1016 if (len > buflen)
1017 len = buflen;
1018
1019 res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
1020
1021 /*
1022 * If the nul at the end of args has been overwritten, then
1023 * assume application is using setproctitle(3).
1024 */
1025 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
1026 len = strnlen(buffer, res);
1027 if (len < res) {
1028 res = len;
1029 } else {
1030 len = env_end - env_start;
1031 if (len > buflen - res)
1032 len = buflen - res;
1033 res += access_process_vm(task, env_start,
1034 buffer+res, len,
1035 FOLL_FORCE);
1036 res = strnlen(buffer, res);
1037 }
1038 }
1039out_mm:
1040 mmput(mm);
1041out:
1042 return res;
1043}
1044
1045int __weak memcmp_pages(struct page *page1, struct page *page2)
1046{
1047 char *addr1, *addr2;
1048 int ret;
1049
1050 addr1 = kmap_local_page(page1);
1051 addr2 = kmap_local_page(page2);
1052 ret = memcmp(addr1, addr2, PAGE_SIZE);
1053 kunmap_local(addr2);
1054 kunmap_local(addr1);
1055 return ret;
1056}
1057
1058#ifdef CONFIG_PRINTK
1059/**
1060 * mem_dump_obj - Print available provenance information
1061 * @object: object for which to find provenance information.
1062 *
1063 * This function uses pr_cont(), so that the caller is expected to have
1064 * printed out whatever preamble is appropriate. The provenance information
1065 * depends on the type of object and on how much debugging is enabled.
1066 * For example, for a slab-cache object, the slab name is printed, and,
1067 * if available, the return address and stack trace from the allocation
1068 * and last free path of that object.
1069 */
1070void mem_dump_obj(void *object)
1071{
1072 const char *type;
1073
1074 if (kmem_dump_obj(object))
1075 return;
1076
1077 if (vmalloc_dump_obj(object))
1078 return;
1079
1080 if (is_vmalloc_addr(object))
1081 type = "vmalloc memory";
1082 else if (virt_addr_valid(object))
1083 type = "non-slab/vmalloc memory";
1084 else if (object == NULL)
1085 type = "NULL pointer";
1086 else if (object == ZERO_SIZE_PTR)
1087 type = "zero-size pointer";
1088 else
1089 type = "non-paged memory";
1090
1091 pr_cont(" %s\n", type);
1092}
1093EXPORT_SYMBOL_GPL(mem_dump_obj);
1094#endif
1095
1096/*
1097 * A driver might set a page logically offline -- PageOffline() -- and
1098 * turn the page inaccessible in the hypervisor; after that, access to page
1099 * content can be fatal.
1100 *
1101 * Some special PFN walkers -- i.e., /proc/kcore -- read content of random
1102 * pages after checking PageOffline(); however, these PFN walkers can race
1103 * with drivers that set PageOffline().
1104 *
1105 * page_offline_freeze()/page_offline_thaw() allows for a subsystem to
1106 * synchronize with such drivers, achieving that a page cannot be set
1107 * PageOffline() while frozen.
1108 *
1109 * page_offline_begin()/page_offline_end() is used by drivers that care about
1110 * such races when setting a page PageOffline().
1111 */
1112static DECLARE_RWSEM(page_offline_rwsem);
1113
1114void page_offline_freeze(void)
1115{
1116 down_read(&page_offline_rwsem);
1117}
1118
1119void page_offline_thaw(void)
1120{
1121 up_read(&page_offline_rwsem);
1122}
1123
1124void page_offline_begin(void)
1125{
1126 down_write(&page_offline_rwsem);
1127}
1128EXPORT_SYMBOL(page_offline_begin);
1129
1130void page_offline_end(void)
1131{
1132 up_write(&page_offline_rwsem);
1133}
1134EXPORT_SYMBOL(page_offline_end);
1135
1136#ifndef flush_dcache_folio
1137void flush_dcache_folio(struct folio *folio)
1138{
1139 long i, nr = folio_nr_pages(folio);
1140
1141 for (i = 0; i < nr; i++)
1142 flush_dcache_page(folio_page(folio, i));
1143}
1144EXPORT_SYMBOL(flush_dcache_folio);
1145#endif
1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/mm.h>
3#include <linux/slab.h>
4#include <linux/string.h>
5#include <linux/compiler.h>
6#include <linux/export.h>
7#include <linux/err.h>
8#include <linux/sched.h>
9#include <linux/sched/mm.h>
10#include <linux/sched/signal.h>
11#include <linux/sched/task_stack.h>
12#include <linux/security.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/mman.h>
16#include <linux/hugetlb.h>
17#include <linux/vmalloc.h>
18#include <linux/userfaultfd_k.h>
19#include <linux/elf.h>
20#include <linux/elf-randomize.h>
21#include <linux/personality.h>
22#include <linux/random.h>
23#include <linux/processor.h>
24#include <linux/sizes.h>
25#include <linux/compat.h>
26
27#include <linux/uaccess.h>
28
29#include "internal.h"
30#include "swap.h"
31
32/**
33 * kfree_const - conditionally free memory
34 * @x: pointer to the memory
35 *
36 * Function calls kfree only if @x is not in .rodata section.
37 */
38void kfree_const(const void *x)
39{
40 if (!is_kernel_rodata((unsigned long)x))
41 kfree(x);
42}
43EXPORT_SYMBOL(kfree_const);
44
45/**
46 * kstrdup - allocate space for and copy an existing string
47 * @s: the string to duplicate
48 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
49 *
50 * Return: newly allocated copy of @s or %NULL in case of error
51 */
52char *kstrdup(const char *s, gfp_t gfp)
53{
54 size_t len;
55 char *buf;
56
57 if (!s)
58 return NULL;
59
60 len = strlen(s) + 1;
61 buf = kmalloc_track_caller(len, gfp);
62 if (buf)
63 memcpy(buf, s, len);
64 return buf;
65}
66EXPORT_SYMBOL(kstrdup);
67
68/**
69 * kstrdup_const - conditionally duplicate an existing const string
70 * @s: the string to duplicate
71 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
72 *
73 * Note: Strings allocated by kstrdup_const should be freed by kfree_const and
74 * must not be passed to krealloc().
75 *
76 * Return: source string if it is in .rodata section otherwise
77 * fallback to kstrdup.
78 */
79const char *kstrdup_const(const char *s, gfp_t gfp)
80{
81 if (is_kernel_rodata((unsigned long)s))
82 return s;
83
84 return kstrdup(s, gfp);
85}
86EXPORT_SYMBOL(kstrdup_const);
87
88/**
89 * kstrndup - allocate space for and copy an existing string
90 * @s: the string to duplicate
91 * @max: read at most @max chars from @s
92 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
93 *
94 * Note: Use kmemdup_nul() instead if the size is known exactly.
95 *
96 * Return: newly allocated copy of @s or %NULL in case of error
97 */
98char *kstrndup(const char *s, size_t max, gfp_t gfp)
99{
100 size_t len;
101 char *buf;
102
103 if (!s)
104 return NULL;
105
106 len = strnlen(s, max);
107 buf = kmalloc_track_caller(len+1, gfp);
108 if (buf) {
109 memcpy(buf, s, len);
110 buf[len] = '\0';
111 }
112 return buf;
113}
114EXPORT_SYMBOL(kstrndup);
115
116/**
117 * kmemdup - duplicate region of memory
118 *
119 * @src: memory region to duplicate
120 * @len: memory region length
121 * @gfp: GFP mask to use
122 *
123 * Return: newly allocated copy of @src or %NULL in case of error
124 */
125void *kmemdup(const void *src, size_t len, gfp_t gfp)
126{
127 void *p;
128
129 p = kmalloc_track_caller(len, gfp);
130 if (p)
131 memcpy(p, src, len);
132 return p;
133}
134EXPORT_SYMBOL(kmemdup);
135
136/**
137 * kmemdup_nul - Create a NUL-terminated string from unterminated data
138 * @s: The data to stringify
139 * @len: The size of the data
140 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
141 *
142 * Return: newly allocated copy of @s with NUL-termination or %NULL in
143 * case of error
144 */
145char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
146{
147 char *buf;
148
149 if (!s)
150 return NULL;
151
152 buf = kmalloc_track_caller(len + 1, gfp);
153 if (buf) {
154 memcpy(buf, s, len);
155 buf[len] = '\0';
156 }
157 return buf;
158}
159EXPORT_SYMBOL(kmemdup_nul);
160
161/**
162 * memdup_user - duplicate memory region from user space
163 *
164 * @src: source address in user space
165 * @len: number of bytes to copy
166 *
167 * Return: an ERR_PTR() on failure. Result is physically
168 * contiguous, to be freed by kfree().
169 */
170void *memdup_user(const void __user *src, size_t len)
171{
172 void *p;
173
174 p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
175 if (!p)
176 return ERR_PTR(-ENOMEM);
177
178 if (copy_from_user(p, src, len)) {
179 kfree(p);
180 return ERR_PTR(-EFAULT);
181 }
182
183 return p;
184}
185EXPORT_SYMBOL(memdup_user);
186
187/**
188 * vmemdup_user - duplicate memory region from user space
189 *
190 * @src: source address in user space
191 * @len: number of bytes to copy
192 *
193 * Return: an ERR_PTR() on failure. Result may be not
194 * physically contiguous. Use kvfree() to free.
195 */
196void *vmemdup_user(const void __user *src, size_t len)
197{
198 void *p;
199
200 p = kvmalloc(len, GFP_USER);
201 if (!p)
202 return ERR_PTR(-ENOMEM);
203
204 if (copy_from_user(p, src, len)) {
205 kvfree(p);
206 return ERR_PTR(-EFAULT);
207 }
208
209 return p;
210}
211EXPORT_SYMBOL(vmemdup_user);
212
213/**
214 * strndup_user - duplicate an existing string from user space
215 * @s: The string to duplicate
216 * @n: Maximum number of bytes to copy, including the trailing NUL.
217 *
218 * Return: newly allocated copy of @s or an ERR_PTR() in case of error
219 */
220char *strndup_user(const char __user *s, long n)
221{
222 char *p;
223 long length;
224
225 length = strnlen_user(s, n);
226
227 if (!length)
228 return ERR_PTR(-EFAULT);
229
230 if (length > n)
231 return ERR_PTR(-EINVAL);
232
233 p = memdup_user(s, length);
234
235 if (IS_ERR(p))
236 return p;
237
238 p[length - 1] = '\0';
239
240 return p;
241}
242EXPORT_SYMBOL(strndup_user);
243
244/**
245 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
246 *
247 * @src: source address in user space
248 * @len: number of bytes to copy
249 *
250 * Return: an ERR_PTR() on failure.
251 */
252void *memdup_user_nul(const void __user *src, size_t len)
253{
254 char *p;
255
256 /*
257 * Always use GFP_KERNEL, since copy_from_user() can sleep and
258 * cause pagefault, which makes it pointless to use GFP_NOFS
259 * or GFP_ATOMIC.
260 */
261 p = kmalloc_track_caller(len + 1, GFP_KERNEL);
262 if (!p)
263 return ERR_PTR(-ENOMEM);
264
265 if (copy_from_user(p, src, len)) {
266 kfree(p);
267 return ERR_PTR(-EFAULT);
268 }
269 p[len] = '\0';
270
271 return p;
272}
273EXPORT_SYMBOL(memdup_user_nul);
274
275/* Check if the vma is being used as a stack by this task */
276int vma_is_stack_for_current(struct vm_area_struct *vma)
277{
278 struct task_struct * __maybe_unused t = current;
279
280 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
281}
282
283/*
284 * Change backing file, only valid to use during initial VMA setup.
285 */
286void vma_set_file(struct vm_area_struct *vma, struct file *file)
287{
288 /* Changing an anonymous vma with this is illegal */
289 get_file(file);
290 swap(vma->vm_file, file);
291 fput(file);
292}
293EXPORT_SYMBOL(vma_set_file);
294
295#ifndef STACK_RND_MASK
296#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
297#endif
298
299unsigned long randomize_stack_top(unsigned long stack_top)
300{
301 unsigned long random_variable = 0;
302
303 if (current->flags & PF_RANDOMIZE) {
304 random_variable = get_random_long();
305 random_variable &= STACK_RND_MASK;
306 random_variable <<= PAGE_SHIFT;
307 }
308#ifdef CONFIG_STACK_GROWSUP
309 return PAGE_ALIGN(stack_top) + random_variable;
310#else
311 return PAGE_ALIGN(stack_top) - random_variable;
312#endif
313}
314
315/**
316 * randomize_page - Generate a random, page aligned address
317 * @start: The smallest acceptable address the caller will take.
318 * @range: The size of the area, starting at @start, within which the
319 * random address must fall.
320 *
321 * If @start + @range would overflow, @range is capped.
322 *
323 * NOTE: Historical use of randomize_range, which this replaces, presumed that
324 * @start was already page aligned. We now align it regardless.
325 *
326 * Return: A page aligned address within [start, start + range). On error,
327 * @start is returned.
328 */
329unsigned long randomize_page(unsigned long start, unsigned long range)
330{
331 if (!PAGE_ALIGNED(start)) {
332 range -= PAGE_ALIGN(start) - start;
333 start = PAGE_ALIGN(start);
334 }
335
336 if (start > ULONG_MAX - range)
337 range = ULONG_MAX - start;
338
339 range >>= PAGE_SHIFT;
340
341 if (range == 0)
342 return start;
343
344 return start + (get_random_long() % range << PAGE_SHIFT);
345}
346
347#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
348unsigned long __weak arch_randomize_brk(struct mm_struct *mm)
349{
350 /* Is the current task 32bit ? */
351 if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
352 return randomize_page(mm->brk, SZ_32M);
353
354 return randomize_page(mm->brk, SZ_1G);
355}
356
357unsigned long arch_mmap_rnd(void)
358{
359 unsigned long rnd;
360
361#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
362 if (is_compat_task())
363 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
364 else
365#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
366 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
367
368 return rnd << PAGE_SHIFT;
369}
370
371static int mmap_is_legacy(struct rlimit *rlim_stack)
372{
373 if (current->personality & ADDR_COMPAT_LAYOUT)
374 return 1;
375
376 if (rlim_stack->rlim_cur == RLIM_INFINITY)
377 return 1;
378
379 return sysctl_legacy_va_layout;
380}
381
382/*
383 * Leave enough space between the mmap area and the stack to honour ulimit in
384 * the face of randomisation.
385 */
386#define MIN_GAP (SZ_128M)
387#define MAX_GAP (STACK_TOP / 6 * 5)
388
389static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
390{
391 unsigned long gap = rlim_stack->rlim_cur;
392 unsigned long pad = stack_guard_gap;
393
394 /* Account for stack randomization if necessary */
395 if (current->flags & PF_RANDOMIZE)
396 pad += (STACK_RND_MASK << PAGE_SHIFT);
397
398 /* Values close to RLIM_INFINITY can overflow. */
399 if (gap + pad > gap)
400 gap += pad;
401
402 if (gap < MIN_GAP)
403 gap = MIN_GAP;
404 else if (gap > MAX_GAP)
405 gap = MAX_GAP;
406
407 return PAGE_ALIGN(STACK_TOP - gap - rnd);
408}
409
410void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
411{
412 unsigned long random_factor = 0UL;
413
414 if (current->flags & PF_RANDOMIZE)
415 random_factor = arch_mmap_rnd();
416
417 if (mmap_is_legacy(rlim_stack)) {
418 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
419 mm->get_unmapped_area = arch_get_unmapped_area;
420 } else {
421 mm->mmap_base = mmap_base(random_factor, rlim_stack);
422 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
423 }
424}
425#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
426void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
427{
428 mm->mmap_base = TASK_UNMAPPED_BASE;
429 mm->get_unmapped_area = arch_get_unmapped_area;
430}
431#endif
432
433/**
434 * __account_locked_vm - account locked pages to an mm's locked_vm
435 * @mm: mm to account against
436 * @pages: number of pages to account
437 * @inc: %true if @pages should be considered positive, %false if not
438 * @task: task used to check RLIMIT_MEMLOCK
439 * @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
440 *
441 * Assumes @task and @mm are valid (i.e. at least one reference on each), and
442 * that mmap_lock is held as writer.
443 *
444 * Return:
445 * * 0 on success
446 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
447 */
448int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
449 struct task_struct *task, bool bypass_rlim)
450{
451 unsigned long locked_vm, limit;
452 int ret = 0;
453
454 mmap_assert_write_locked(mm);
455
456 locked_vm = mm->locked_vm;
457 if (inc) {
458 if (!bypass_rlim) {
459 limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
460 if (locked_vm + pages > limit)
461 ret = -ENOMEM;
462 }
463 if (!ret)
464 mm->locked_vm = locked_vm + pages;
465 } else {
466 WARN_ON_ONCE(pages > locked_vm);
467 mm->locked_vm = locked_vm - pages;
468 }
469
470 pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
471 (void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
472 locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
473 ret ? " - exceeded" : "");
474
475 return ret;
476}
477EXPORT_SYMBOL_GPL(__account_locked_vm);
478
479/**
480 * account_locked_vm - account locked pages to an mm's locked_vm
481 * @mm: mm to account against, may be NULL
482 * @pages: number of pages to account
483 * @inc: %true if @pages should be considered positive, %false if not
484 *
485 * Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
486 *
487 * Return:
488 * * 0 on success, or if mm is NULL
489 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
490 */
491int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
492{
493 int ret;
494
495 if (pages == 0 || !mm)
496 return 0;
497
498 mmap_write_lock(mm);
499 ret = __account_locked_vm(mm, pages, inc, current,
500 capable(CAP_IPC_LOCK));
501 mmap_write_unlock(mm);
502
503 return ret;
504}
505EXPORT_SYMBOL_GPL(account_locked_vm);
506
507unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
508 unsigned long len, unsigned long prot,
509 unsigned long flag, unsigned long pgoff)
510{
511 unsigned long ret;
512 struct mm_struct *mm = current->mm;
513 unsigned long populate;
514 LIST_HEAD(uf);
515
516 ret = security_mmap_file(file, prot, flag);
517 if (!ret) {
518 if (mmap_write_lock_killable(mm))
519 return -EINTR;
520 ret = do_mmap(file, addr, len, prot, flag, pgoff, &populate,
521 &uf);
522 mmap_write_unlock(mm);
523 userfaultfd_unmap_complete(mm, &uf);
524 if (populate)
525 mm_populate(ret, populate);
526 }
527 return ret;
528}
529
530unsigned long vm_mmap(struct file *file, unsigned long addr,
531 unsigned long len, unsigned long prot,
532 unsigned long flag, unsigned long offset)
533{
534 if (unlikely(offset + PAGE_ALIGN(len) < offset))
535 return -EINVAL;
536 if (unlikely(offset_in_page(offset)))
537 return -EINVAL;
538
539 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
540}
541EXPORT_SYMBOL(vm_mmap);
542
543/**
544 * kvmalloc_node - attempt to allocate physically contiguous memory, but upon
545 * failure, fall back to non-contiguous (vmalloc) allocation.
546 * @size: size of the request.
547 * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
548 * @node: numa node to allocate from
549 *
550 * Uses kmalloc to get the memory but if the allocation fails then falls back
551 * to the vmalloc allocator. Use kvfree for freeing the memory.
552 *
553 * GFP_NOWAIT and GFP_ATOMIC are not supported, neither is the __GFP_NORETRY modifier.
554 * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
555 * preferable to the vmalloc fallback, due to visible performance drawbacks.
556 *
557 * Return: pointer to the allocated memory of %NULL in case of failure
558 */
559void *kvmalloc_node(size_t size, gfp_t flags, int node)
560{
561 gfp_t kmalloc_flags = flags;
562 void *ret;
563
564 /*
565 * We want to attempt a large physically contiguous block first because
566 * it is less likely to fragment multiple larger blocks and therefore
567 * contribute to a long term fragmentation less than vmalloc fallback.
568 * However make sure that larger requests are not too disruptive - no
569 * OOM killer and no allocation failure warnings as we have a fallback.
570 */
571 if (size > PAGE_SIZE) {
572 kmalloc_flags |= __GFP_NOWARN;
573
574 if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
575 kmalloc_flags |= __GFP_NORETRY;
576
577 /* nofail semantic is implemented by the vmalloc fallback */
578 kmalloc_flags &= ~__GFP_NOFAIL;
579 }
580
581 ret = kmalloc_node(size, kmalloc_flags, node);
582
583 /*
584 * It doesn't really make sense to fallback to vmalloc for sub page
585 * requests
586 */
587 if (ret || size <= PAGE_SIZE)
588 return ret;
589
590 /* non-sleeping allocations are not supported by vmalloc */
591 if (!gfpflags_allow_blocking(flags))
592 return NULL;
593
594 /* Don't even allow crazy sizes */
595 if (unlikely(size > INT_MAX)) {
596 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
597 return NULL;
598 }
599
600 /*
601 * kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
602 * since the callers already cannot assume anything
603 * about the resulting pointer, and cannot play
604 * protection games.
605 */
606 return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
607 flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
608 node, __builtin_return_address(0));
609}
610EXPORT_SYMBOL(kvmalloc_node);
611
612/**
613 * kvfree() - Free memory.
614 * @addr: Pointer to allocated memory.
615 *
616 * kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
617 * It is slightly more efficient to use kfree() or vfree() if you are certain
618 * that you know which one to use.
619 *
620 * Context: Either preemptible task context or not-NMI interrupt.
621 */
622void kvfree(const void *addr)
623{
624 if (is_vmalloc_addr(addr))
625 vfree(addr);
626 else
627 kfree(addr);
628}
629EXPORT_SYMBOL(kvfree);
630
631/**
632 * kvfree_sensitive - Free a data object containing sensitive information.
633 * @addr: address of the data object to be freed.
634 * @len: length of the data object.
635 *
636 * Use the special memzero_explicit() function to clear the content of a
637 * kvmalloc'ed object containing sensitive data to make sure that the
638 * compiler won't optimize out the data clearing.
639 */
640void kvfree_sensitive(const void *addr, size_t len)
641{
642 if (likely(!ZERO_OR_NULL_PTR(addr))) {
643 memzero_explicit((void *)addr, len);
644 kvfree(addr);
645 }
646}
647EXPORT_SYMBOL(kvfree_sensitive);
648
649void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
650{
651 void *newp;
652
653 if (oldsize >= newsize)
654 return (void *)p;
655 newp = kvmalloc(newsize, flags);
656 if (!newp)
657 return NULL;
658 memcpy(newp, p, oldsize);
659 kvfree(p);
660 return newp;
661}
662EXPORT_SYMBOL(kvrealloc);
663
664/**
665 * __vmalloc_array - allocate memory for a virtually contiguous array.
666 * @n: number of elements.
667 * @size: element size.
668 * @flags: the type of memory to allocate (see kmalloc).
669 */
670void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
671{
672 size_t bytes;
673
674 if (unlikely(check_mul_overflow(n, size, &bytes)))
675 return NULL;
676 return __vmalloc(bytes, flags);
677}
678EXPORT_SYMBOL(__vmalloc_array);
679
680/**
681 * vmalloc_array - allocate memory for a virtually contiguous array.
682 * @n: number of elements.
683 * @size: element size.
684 */
685void *vmalloc_array(size_t n, size_t size)
686{
687 return __vmalloc_array(n, size, GFP_KERNEL);
688}
689EXPORT_SYMBOL(vmalloc_array);
690
691/**
692 * __vcalloc - allocate and zero memory for a virtually contiguous array.
693 * @n: number of elements.
694 * @size: element size.
695 * @flags: the type of memory to allocate (see kmalloc).
696 */
697void *__vcalloc(size_t n, size_t size, gfp_t flags)
698{
699 return __vmalloc_array(n, size, flags | __GFP_ZERO);
700}
701EXPORT_SYMBOL(__vcalloc);
702
703/**
704 * vcalloc - allocate and zero memory for a virtually contiguous array.
705 * @n: number of elements.
706 * @size: element size.
707 */
708void *vcalloc(size_t n, size_t size)
709{
710 return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
711}
712EXPORT_SYMBOL(vcalloc);
713
714/* Neutral page->mapping pointer to address_space or anon_vma or other */
715void *page_rmapping(struct page *page)
716{
717 return folio_raw_mapping(page_folio(page));
718}
719
720struct anon_vma *folio_anon_vma(struct folio *folio)
721{
722 unsigned long mapping = (unsigned long)folio->mapping;
723
724 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
725 return NULL;
726 return (void *)(mapping - PAGE_MAPPING_ANON);
727}
728
729/**
730 * folio_mapping - Find the mapping where this folio is stored.
731 * @folio: The folio.
732 *
733 * For folios which are in the page cache, return the mapping that this
734 * page belongs to. Folios in the swap cache return the swap mapping
735 * this page is stored in (which is different from the mapping for the
736 * swap file or swap device where the data is stored).
737 *
738 * You can call this for folios which aren't in the swap cache or page
739 * cache and it will return NULL.
740 */
741struct address_space *folio_mapping(struct folio *folio)
742{
743 struct address_space *mapping;
744
745 /* This happens if someone calls flush_dcache_page on slab page */
746 if (unlikely(folio_test_slab(folio)))
747 return NULL;
748
749 if (unlikely(folio_test_swapcache(folio)))
750 return swap_address_space(folio_swap_entry(folio));
751
752 mapping = folio->mapping;
753 if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
754 return NULL;
755
756 return mapping;
757}
758EXPORT_SYMBOL(folio_mapping);
759
760/**
761 * folio_copy - Copy the contents of one folio to another.
762 * @dst: Folio to copy to.
763 * @src: Folio to copy from.
764 *
765 * The bytes in the folio represented by @src are copied to @dst.
766 * Assumes the caller has validated that @dst is at least as large as @src.
767 * Can be called in atomic context for order-0 folios, but if the folio is
768 * larger, it may sleep.
769 */
770void folio_copy(struct folio *dst, struct folio *src)
771{
772 long i = 0;
773 long nr = folio_nr_pages(src);
774
775 for (;;) {
776 copy_highpage(folio_page(dst, i), folio_page(src, i));
777 if (++i == nr)
778 break;
779 cond_resched();
780 }
781}
782
783int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
784int sysctl_overcommit_ratio __read_mostly = 50;
785unsigned long sysctl_overcommit_kbytes __read_mostly;
786int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
787unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
788unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
789
790int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer,
791 size_t *lenp, loff_t *ppos)
792{
793 int ret;
794
795 ret = proc_dointvec(table, write, buffer, lenp, ppos);
796 if (ret == 0 && write)
797 sysctl_overcommit_kbytes = 0;
798 return ret;
799}
800
801static void sync_overcommit_as(struct work_struct *dummy)
802{
803 percpu_counter_sync(&vm_committed_as);
804}
805
806int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer,
807 size_t *lenp, loff_t *ppos)
808{
809 struct ctl_table t;
810 int new_policy = -1;
811 int ret;
812
813 /*
814 * The deviation of sync_overcommit_as could be big with loose policy
815 * like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to
816 * strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply
817 * with the strict "NEVER", and to avoid possible race condition (even
818 * though user usually won't too frequently do the switching to policy
819 * OVERCOMMIT_NEVER), the switch is done in the following order:
820 * 1. changing the batch
821 * 2. sync percpu count on each CPU
822 * 3. switch the policy
823 */
824 if (write) {
825 t = *table;
826 t.data = &new_policy;
827 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
828 if (ret || new_policy == -1)
829 return ret;
830
831 mm_compute_batch(new_policy);
832 if (new_policy == OVERCOMMIT_NEVER)
833 schedule_on_each_cpu(sync_overcommit_as);
834 sysctl_overcommit_memory = new_policy;
835 } else {
836 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
837 }
838
839 return ret;
840}
841
842int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer,
843 size_t *lenp, loff_t *ppos)
844{
845 int ret;
846
847 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
848 if (ret == 0 && write)
849 sysctl_overcommit_ratio = 0;
850 return ret;
851}
852
853/*
854 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
855 */
856unsigned long vm_commit_limit(void)
857{
858 unsigned long allowed;
859
860 if (sysctl_overcommit_kbytes)
861 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
862 else
863 allowed = ((totalram_pages() - hugetlb_total_pages())
864 * sysctl_overcommit_ratio / 100);
865 allowed += total_swap_pages;
866
867 return allowed;
868}
869
870/*
871 * Make sure vm_committed_as in one cacheline and not cacheline shared with
872 * other variables. It can be updated by several CPUs frequently.
873 */
874struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
875
876/*
877 * The global memory commitment made in the system can be a metric
878 * that can be used to drive ballooning decisions when Linux is hosted
879 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
880 * balancing memory across competing virtual machines that are hosted.
881 * Several metrics drive this policy engine including the guest reported
882 * memory commitment.
883 *
884 * The time cost of this is very low for small platforms, and for big
885 * platform like a 2S/36C/72T Skylake server, in worst case where
886 * vm_committed_as's spinlock is under severe contention, the time cost
887 * could be about 30~40 microseconds.
888 */
889unsigned long vm_memory_committed(void)
890{
891 return percpu_counter_sum_positive(&vm_committed_as);
892}
893EXPORT_SYMBOL_GPL(vm_memory_committed);
894
895/*
896 * Check that a process has enough memory to allocate a new virtual
897 * mapping. 0 means there is enough memory for the allocation to
898 * succeed and -ENOMEM implies there is not.
899 *
900 * We currently support three overcommit policies, which are set via the
901 * vm.overcommit_memory sysctl. See Documentation/mm/overcommit-accounting.rst
902 *
903 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
904 * Additional code 2002 Jul 20 by Robert Love.
905 *
906 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
907 *
908 * Note this is a helper function intended to be used by LSMs which
909 * wish to use this logic.
910 */
911int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
912{
913 long allowed;
914
915 vm_acct_memory(pages);
916
917 /*
918 * Sometimes we want to use more memory than we have
919 */
920 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
921 return 0;
922
923 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
924 if (pages > totalram_pages() + total_swap_pages)
925 goto error;
926 return 0;
927 }
928
929 allowed = vm_commit_limit();
930 /*
931 * Reserve some for root
932 */
933 if (!cap_sys_admin)
934 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
935
936 /*
937 * Don't let a single process grow so big a user can't recover
938 */
939 if (mm) {
940 long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
941
942 allowed -= min_t(long, mm->total_vm / 32, reserve);
943 }
944
945 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
946 return 0;
947error:
948 pr_warn_ratelimited("%s: pid: %d, comm: %s, no enough memory for the allocation\n",
949 __func__, current->pid, current->comm);
950 vm_unacct_memory(pages);
951
952 return -ENOMEM;
953}
954
955/**
956 * get_cmdline() - copy the cmdline value to a buffer.
957 * @task: the task whose cmdline value to copy.
958 * @buffer: the buffer to copy to.
959 * @buflen: the length of the buffer. Larger cmdline values are truncated
960 * to this length.
961 *
962 * Return: the size of the cmdline field copied. Note that the copy does
963 * not guarantee an ending NULL byte.
964 */
965int get_cmdline(struct task_struct *task, char *buffer, int buflen)
966{
967 int res = 0;
968 unsigned int len;
969 struct mm_struct *mm = get_task_mm(task);
970 unsigned long arg_start, arg_end, env_start, env_end;
971 if (!mm)
972 goto out;
973 if (!mm->arg_end)
974 goto out_mm; /* Shh! No looking before we're done */
975
976 spin_lock(&mm->arg_lock);
977 arg_start = mm->arg_start;
978 arg_end = mm->arg_end;
979 env_start = mm->env_start;
980 env_end = mm->env_end;
981 spin_unlock(&mm->arg_lock);
982
983 len = arg_end - arg_start;
984
985 if (len > buflen)
986 len = buflen;
987
988 res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
989
990 /*
991 * If the nul at the end of args has been overwritten, then
992 * assume application is using setproctitle(3).
993 */
994 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
995 len = strnlen(buffer, res);
996 if (len < res) {
997 res = len;
998 } else {
999 len = env_end - env_start;
1000 if (len > buflen - res)
1001 len = buflen - res;
1002 res += access_process_vm(task, env_start,
1003 buffer+res, len,
1004 FOLL_FORCE);
1005 res = strnlen(buffer, res);
1006 }
1007 }
1008out_mm:
1009 mmput(mm);
1010out:
1011 return res;
1012}
1013
1014int __weak memcmp_pages(struct page *page1, struct page *page2)
1015{
1016 char *addr1, *addr2;
1017 int ret;
1018
1019 addr1 = kmap_atomic(page1);
1020 addr2 = kmap_atomic(page2);
1021 ret = memcmp(addr1, addr2, PAGE_SIZE);
1022 kunmap_atomic(addr2);
1023 kunmap_atomic(addr1);
1024 return ret;
1025}
1026
1027#ifdef CONFIG_PRINTK
1028/**
1029 * mem_dump_obj - Print available provenance information
1030 * @object: object for which to find provenance information.
1031 *
1032 * This function uses pr_cont(), so that the caller is expected to have
1033 * printed out whatever preamble is appropriate. The provenance information
1034 * depends on the type of object and on how much debugging is enabled.
1035 * For example, for a slab-cache object, the slab name is printed, and,
1036 * if available, the return address and stack trace from the allocation
1037 * and last free path of that object.
1038 */
1039void mem_dump_obj(void *object)
1040{
1041 const char *type;
1042
1043 if (kmem_valid_obj(object)) {
1044 kmem_dump_obj(object);
1045 return;
1046 }
1047
1048 if (vmalloc_dump_obj(object))
1049 return;
1050
1051 if (virt_addr_valid(object))
1052 type = "non-slab/vmalloc memory";
1053 else if (object == NULL)
1054 type = "NULL pointer";
1055 else if (object == ZERO_SIZE_PTR)
1056 type = "zero-size pointer";
1057 else
1058 type = "non-paged memory";
1059
1060 pr_cont(" %s\n", type);
1061}
1062EXPORT_SYMBOL_GPL(mem_dump_obj);
1063#endif
1064
1065/*
1066 * A driver might set a page logically offline -- PageOffline() -- and
1067 * turn the page inaccessible in the hypervisor; after that, access to page
1068 * content can be fatal.
1069 *
1070 * Some special PFN walkers -- i.e., /proc/kcore -- read content of random
1071 * pages after checking PageOffline(); however, these PFN walkers can race
1072 * with drivers that set PageOffline().
1073 *
1074 * page_offline_freeze()/page_offline_thaw() allows for a subsystem to
1075 * synchronize with such drivers, achieving that a page cannot be set
1076 * PageOffline() while frozen.
1077 *
1078 * page_offline_begin()/page_offline_end() is used by drivers that care about
1079 * such races when setting a page PageOffline().
1080 */
1081static DECLARE_RWSEM(page_offline_rwsem);
1082
1083void page_offline_freeze(void)
1084{
1085 down_read(&page_offline_rwsem);
1086}
1087
1088void page_offline_thaw(void)
1089{
1090 up_read(&page_offline_rwsem);
1091}
1092
1093void page_offline_begin(void)
1094{
1095 down_write(&page_offline_rwsem);
1096}
1097EXPORT_SYMBOL(page_offline_begin);
1098
1099void page_offline_end(void)
1100{
1101 up_write(&page_offline_rwsem);
1102}
1103EXPORT_SYMBOL(page_offline_end);
1104
1105#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
1106void flush_dcache_folio(struct folio *folio)
1107{
1108 long i, nr = folio_nr_pages(folio);
1109
1110 for (i = 0; i < nr; i++)
1111 flush_dcache_page(folio_page(folio, i));
1112}
1113EXPORT_SYMBOL(flush_dcache_folio);
1114#endif