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