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 */ 38 void kfree_const(const void *x) 39 { 40 if (!is_kernel_rodata((unsigned long)x)) 41 kfree(x); 42 } 43 EXPORT_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 */ 52 noinline 53 char *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 } 67 EXPORT_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 */ 80 const 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 } 87 EXPORT_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 */ 99 char *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 } 115 EXPORT_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 */ 127 void *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 } 136 EXPORT_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 */ 148 void *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 } 157 EXPORT_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 */ 168 char *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 } 182 EXPORT_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 */ 193 void *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 } 208 EXPORT_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 */ 219 void *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 } 234 EXPORT_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 */ 243 char *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 } 265 EXPORT_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 */ 275 void *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 } 296 EXPORT_SYMBOL(memdup_user_nul); 297 298 /* Check if the vma is being used as a stack by this task */ 299 int 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 */ 309 void 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 } 316 EXPORT_SYMBOL(vma_set_file); 317 318 #ifndef STACK_RND_MASK 319 #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */ 320 #endif 321 322 unsigned 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 */ 352 unsigned 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 371 unsigned 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 } 379 380 unsigned 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 } 393 394 static 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) 414 415 static 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 } 445 446 void 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) 462 void 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 */ 484 int __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 } 513 EXPORT_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 */ 527 int 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 } 541 EXPORT_SYMBOL_GPL(account_locked_vm); 542 543 unsigned 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 } 565 566 unsigned 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 } 577 EXPORT_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 */ 595 void *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 } 646 EXPORT_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 */ 658 void kvfree(const void *addr) 659 { 660 if (is_vmalloc_addr(addr)) 661 vfree(addr); 662 else 663 kfree(addr); 664 } 665 EXPORT_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 */ 676 void 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 } 683 EXPORT_SYMBOL(kvfree_sensitive); 684 685 void *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 } 698 EXPORT_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 */ 706 void *__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 } 714 EXPORT_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 */ 721 void *vmalloc_array(size_t n, size_t size) 722 { 723 return __vmalloc_array(n, size, GFP_KERNEL); 724 } 725 EXPORT_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 */ 733 void *__vcalloc(size_t n, size_t size, gfp_t flags) 734 { 735 return __vmalloc_array(n, size, flags | __GFP_ZERO); 736 } 737 EXPORT_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 */ 744 void *vcalloc(size_t n, size_t size) 745 { 746 return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO); 747 } 748 EXPORT_SYMBOL(vcalloc); 749 750 struct 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 */ 771 struct 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 } 788 EXPORT_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 */ 800 void 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 } 812 EXPORT_SYMBOL(folio_copy); 813 814 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; 815 int sysctl_overcommit_ratio __read_mostly = 50; 816 unsigned long sysctl_overcommit_kbytes __read_mostly; 817 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 818 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ 819 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ 820 821 int 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 } 831 832 static void sync_overcommit_as(struct work_struct *dummy) 833 { 834 percpu_counter_sync(&vm_committed_as); 835 } 836 837 int 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 } 872 873 int 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 */ 887 unsigned 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 */ 905 struct 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 */ 920 unsigned long vm_memory_committed(void) 921 { 922 return percpu_counter_sum_positive(&vm_committed_as); 923 } 924 EXPORT_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 */ 942 int __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; 978 error: 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 */ 996 int 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 } 1039 out_mm: 1040 mmput(mm); 1041 out: 1042 return res; 1043 } 1044 1045 int __weak memcmp_pages(struct page *page1, struct page *page2) 1046 { 1047 char *addr1, *addr2; 1048 int ret; 1049 1050 addr1 = kmap_atomic(page1); 1051 addr2 = kmap_atomic(page2); 1052 ret = memcmp(addr1, addr2, PAGE_SIZE); 1053 kunmap_atomic(addr2); 1054 kunmap_atomic(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 */ 1070 void 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 } 1093 EXPORT_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 */ 1112 static DECLARE_RWSEM(page_offline_rwsem); 1113 1114 void page_offline_freeze(void) 1115 { 1116 down_read(&page_offline_rwsem); 1117 } 1118 1119 void page_offline_thaw(void) 1120 { 1121 up_read(&page_offline_rwsem); 1122 } 1123 1124 void page_offline_begin(void) 1125 { 1126 down_write(&page_offline_rwsem); 1127 } 1128 EXPORT_SYMBOL(page_offline_begin); 1129 1130 void page_offline_end(void) 1131 { 1132 up_write(&page_offline_rwsem); 1133 } 1134 EXPORT_SYMBOL(page_offline_end); 1135 1136 #ifndef flush_dcache_folio 1137 void 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 } 1144 EXPORT_SYMBOL(flush_dcache_folio); 1145 #endif 1146