1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Slab allocator functions that are independent of the allocator strategy 4 * 5 * (C) 2012 Christoph Lameter <cl@linux.com> 6 */ 7 #include <linux/slab.h> 8 9 #include <linux/mm.h> 10 #include <linux/poison.h> 11 #include <linux/interrupt.h> 12 #include <linux/memory.h> 13 #include <linux/cache.h> 14 #include <linux/compiler.h> 15 #include <linux/kfence.h> 16 #include <linux/module.h> 17 #include <linux/cpu.h> 18 #include <linux/uaccess.h> 19 #include <linux/seq_file.h> 20 #include <linux/proc_fs.h> 21 #include <linux/debugfs.h> 22 #include <linux/kasan.h> 23 #include <asm/cacheflush.h> 24 #include <asm/tlbflush.h> 25 #include <asm/page.h> 26 #include <linux/memcontrol.h> 27 #include <linux/stackdepot.h> 28 29 #include "internal.h" 30 #include "slab.h" 31 32 #define CREATE_TRACE_POINTS 33 #include <trace/events/kmem.h> 34 35 enum slab_state slab_state; 36 LIST_HEAD(slab_caches); 37 DEFINE_MUTEX(slab_mutex); 38 struct kmem_cache *kmem_cache; 39 40 static LIST_HEAD(slab_caches_to_rcu_destroy); 41 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 42 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 43 slab_caches_to_rcu_destroy_workfn); 44 45 /* 46 * Set of flags that will prevent slab merging 47 */ 48 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 49 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 50 SLAB_FAILSLAB | kasan_never_merge()) 51 52 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 53 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 54 55 /* 56 * Merge control. If this is set then no merging of slab caches will occur. 57 */ 58 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 59 60 static int __init setup_slab_nomerge(char *str) 61 { 62 slab_nomerge = true; 63 return 1; 64 } 65 66 static int __init setup_slab_merge(char *str) 67 { 68 slab_nomerge = false; 69 return 1; 70 } 71 72 #ifdef CONFIG_SLUB 73 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 74 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0); 75 #endif 76 77 __setup("slab_nomerge", setup_slab_nomerge); 78 __setup("slab_merge", setup_slab_merge); 79 80 /* 81 * Determine the size of a slab object 82 */ 83 unsigned int kmem_cache_size(struct kmem_cache *s) 84 { 85 return s->object_size; 86 } 87 EXPORT_SYMBOL(kmem_cache_size); 88 89 #ifdef CONFIG_DEBUG_VM 90 static int kmem_cache_sanity_check(const char *name, unsigned int size) 91 { 92 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { 93 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 94 return -EINVAL; 95 } 96 97 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 98 return 0; 99 } 100 #else 101 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 102 { 103 return 0; 104 } 105 #endif 106 107 /* 108 * Figure out what the alignment of the objects will be given a set of 109 * flags, a user specified alignment and the size of the objects. 110 */ 111 static unsigned int calculate_alignment(slab_flags_t flags, 112 unsigned int align, unsigned int size) 113 { 114 /* 115 * If the user wants hardware cache aligned objects then follow that 116 * suggestion if the object is sufficiently large. 117 * 118 * The hardware cache alignment cannot override the specified 119 * alignment though. If that is greater then use it. 120 */ 121 if (flags & SLAB_HWCACHE_ALIGN) { 122 unsigned int ralign; 123 124 ralign = cache_line_size(); 125 while (size <= ralign / 2) 126 ralign /= 2; 127 align = max(align, ralign); 128 } 129 130 align = max(align, arch_slab_minalign()); 131 132 return ALIGN(align, sizeof(void *)); 133 } 134 135 /* 136 * Find a mergeable slab cache 137 */ 138 int slab_unmergeable(struct kmem_cache *s) 139 { 140 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 141 return 1; 142 143 if (s->ctor) 144 return 1; 145 146 if (s->usersize) 147 return 1; 148 149 /* 150 * We may have set a slab to be unmergeable during bootstrap. 151 */ 152 if (s->refcount < 0) 153 return 1; 154 155 return 0; 156 } 157 158 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 159 slab_flags_t flags, const char *name, void (*ctor)(void *)) 160 { 161 struct kmem_cache *s; 162 163 if (slab_nomerge) 164 return NULL; 165 166 if (ctor) 167 return NULL; 168 169 size = ALIGN(size, sizeof(void *)); 170 align = calculate_alignment(flags, align, size); 171 size = ALIGN(size, align); 172 flags = kmem_cache_flags(size, flags, name); 173 174 if (flags & SLAB_NEVER_MERGE) 175 return NULL; 176 177 list_for_each_entry_reverse(s, &slab_caches, list) { 178 if (slab_unmergeable(s)) 179 continue; 180 181 if (size > s->size) 182 continue; 183 184 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 185 continue; 186 /* 187 * Check if alignment is compatible. 188 * Courtesy of Adrian Drzewiecki 189 */ 190 if ((s->size & ~(align - 1)) != s->size) 191 continue; 192 193 if (s->size - size >= sizeof(void *)) 194 continue; 195 196 if (IS_ENABLED(CONFIG_SLAB) && align && 197 (align > s->align || s->align % align)) 198 continue; 199 200 return s; 201 } 202 return NULL; 203 } 204 205 static struct kmem_cache *create_cache(const char *name, 206 unsigned int object_size, unsigned int align, 207 slab_flags_t flags, unsigned int useroffset, 208 unsigned int usersize, void (*ctor)(void *), 209 struct kmem_cache *root_cache) 210 { 211 struct kmem_cache *s; 212 int err; 213 214 if (WARN_ON(useroffset + usersize > object_size)) 215 useroffset = usersize = 0; 216 217 err = -ENOMEM; 218 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 219 if (!s) 220 goto out; 221 222 s->name = name; 223 s->size = s->object_size = object_size; 224 s->align = align; 225 s->ctor = ctor; 226 s->useroffset = useroffset; 227 s->usersize = usersize; 228 229 err = __kmem_cache_create(s, flags); 230 if (err) 231 goto out_free_cache; 232 233 s->refcount = 1; 234 list_add(&s->list, &slab_caches); 235 out: 236 if (err) 237 return ERR_PTR(err); 238 return s; 239 240 out_free_cache: 241 kmem_cache_free(kmem_cache, s); 242 goto out; 243 } 244 245 /** 246 * kmem_cache_create_usercopy - Create a cache with a region suitable 247 * for copying to userspace 248 * @name: A string which is used in /proc/slabinfo to identify this cache. 249 * @size: The size of objects to be created in this cache. 250 * @align: The required alignment for the objects. 251 * @flags: SLAB flags 252 * @useroffset: Usercopy region offset 253 * @usersize: Usercopy region size 254 * @ctor: A constructor for the objects. 255 * 256 * Cannot be called within a interrupt, but can be interrupted. 257 * The @ctor is run when new pages are allocated by the cache. 258 * 259 * The flags are 260 * 261 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 262 * to catch references to uninitialised memory. 263 * 264 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 265 * for buffer overruns. 266 * 267 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 268 * cacheline. This can be beneficial if you're counting cycles as closely 269 * as davem. 270 * 271 * Return: a pointer to the cache on success, NULL on failure. 272 */ 273 struct kmem_cache * 274 kmem_cache_create_usercopy(const char *name, 275 unsigned int size, unsigned int align, 276 slab_flags_t flags, 277 unsigned int useroffset, unsigned int usersize, 278 void (*ctor)(void *)) 279 { 280 struct kmem_cache *s = NULL; 281 const char *cache_name; 282 int err; 283 284 #ifdef CONFIG_SLUB_DEBUG 285 /* 286 * If no slub_debug was enabled globally, the static key is not yet 287 * enabled by setup_slub_debug(). Enable it if the cache is being 288 * created with any of the debugging flags passed explicitly. 289 * It's also possible that this is the first cache created with 290 * SLAB_STORE_USER and we should init stack_depot for it. 291 */ 292 if (flags & SLAB_DEBUG_FLAGS) 293 static_branch_enable(&slub_debug_enabled); 294 if (flags & SLAB_STORE_USER) 295 stack_depot_init(); 296 #endif 297 298 mutex_lock(&slab_mutex); 299 300 err = kmem_cache_sanity_check(name, size); 301 if (err) { 302 goto out_unlock; 303 } 304 305 /* Refuse requests with allocator specific flags */ 306 if (flags & ~SLAB_FLAGS_PERMITTED) { 307 err = -EINVAL; 308 goto out_unlock; 309 } 310 311 /* 312 * Some allocators will constraint the set of valid flags to a subset 313 * of all flags. We expect them to define CACHE_CREATE_MASK in this 314 * case, and we'll just provide them with a sanitized version of the 315 * passed flags. 316 */ 317 flags &= CACHE_CREATE_MASK; 318 319 /* Fail closed on bad usersize of useroffset values. */ 320 if (WARN_ON(!usersize && useroffset) || 321 WARN_ON(size < usersize || size - usersize < useroffset)) 322 usersize = useroffset = 0; 323 324 if (!usersize) 325 s = __kmem_cache_alias(name, size, align, flags, ctor); 326 if (s) 327 goto out_unlock; 328 329 cache_name = kstrdup_const(name, GFP_KERNEL); 330 if (!cache_name) { 331 err = -ENOMEM; 332 goto out_unlock; 333 } 334 335 s = create_cache(cache_name, size, 336 calculate_alignment(flags, align, size), 337 flags, useroffset, usersize, ctor, NULL); 338 if (IS_ERR(s)) { 339 err = PTR_ERR(s); 340 kfree_const(cache_name); 341 } 342 343 out_unlock: 344 mutex_unlock(&slab_mutex); 345 346 if (err) { 347 if (flags & SLAB_PANIC) 348 panic("%s: Failed to create slab '%s'. Error %d\n", 349 __func__, name, err); 350 else { 351 pr_warn("%s(%s) failed with error %d\n", 352 __func__, name, err); 353 dump_stack(); 354 } 355 return NULL; 356 } 357 return s; 358 } 359 EXPORT_SYMBOL(kmem_cache_create_usercopy); 360 361 /** 362 * kmem_cache_create - Create a cache. 363 * @name: A string which is used in /proc/slabinfo to identify this cache. 364 * @size: The size of objects to be created in this cache. 365 * @align: The required alignment for the objects. 366 * @flags: SLAB flags 367 * @ctor: A constructor for the objects. 368 * 369 * Cannot be called within a interrupt, but can be interrupted. 370 * The @ctor is run when new pages are allocated by the cache. 371 * 372 * The flags are 373 * 374 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 375 * to catch references to uninitialised memory. 376 * 377 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 378 * for buffer overruns. 379 * 380 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 381 * cacheline. This can be beneficial if you're counting cycles as closely 382 * as davem. 383 * 384 * Return: a pointer to the cache on success, NULL on failure. 385 */ 386 struct kmem_cache * 387 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 388 slab_flags_t flags, void (*ctor)(void *)) 389 { 390 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 391 ctor); 392 } 393 EXPORT_SYMBOL(kmem_cache_create); 394 395 #ifdef SLAB_SUPPORTS_SYSFS 396 /* 397 * For a given kmem_cache, kmem_cache_destroy() should only be called 398 * once or there will be a use-after-free problem. The actual deletion 399 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock 400 * protection. So they are now done without holding those locks. 401 * 402 * Note that there will be a slight delay in the deletion of sysfs files 403 * if kmem_cache_release() is called indrectly from a work function. 404 */ 405 static void kmem_cache_release(struct kmem_cache *s) 406 { 407 sysfs_slab_unlink(s); 408 sysfs_slab_release(s); 409 } 410 #else 411 static void kmem_cache_release(struct kmem_cache *s) 412 { 413 slab_kmem_cache_release(s); 414 } 415 #endif 416 417 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 418 { 419 LIST_HEAD(to_destroy); 420 struct kmem_cache *s, *s2; 421 422 /* 423 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 424 * @slab_caches_to_rcu_destroy list. The slab pages are freed 425 * through RCU and the associated kmem_cache are dereferenced 426 * while freeing the pages, so the kmem_caches should be freed only 427 * after the pending RCU operations are finished. As rcu_barrier() 428 * is a pretty slow operation, we batch all pending destructions 429 * asynchronously. 430 */ 431 mutex_lock(&slab_mutex); 432 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 433 mutex_unlock(&slab_mutex); 434 435 if (list_empty(&to_destroy)) 436 return; 437 438 rcu_barrier(); 439 440 list_for_each_entry_safe(s, s2, &to_destroy, list) { 441 debugfs_slab_release(s); 442 kfence_shutdown_cache(s); 443 kmem_cache_release(s); 444 } 445 } 446 447 static int shutdown_cache(struct kmem_cache *s) 448 { 449 /* free asan quarantined objects */ 450 kasan_cache_shutdown(s); 451 452 if (__kmem_cache_shutdown(s) != 0) 453 return -EBUSY; 454 455 list_del(&s->list); 456 457 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 458 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 459 schedule_work(&slab_caches_to_rcu_destroy_work); 460 } else { 461 kfence_shutdown_cache(s); 462 debugfs_slab_release(s); 463 } 464 465 return 0; 466 } 467 468 void slab_kmem_cache_release(struct kmem_cache *s) 469 { 470 __kmem_cache_release(s); 471 kfree_const(s->name); 472 kmem_cache_free(kmem_cache, s); 473 } 474 475 void kmem_cache_destroy(struct kmem_cache *s) 476 { 477 int refcnt; 478 bool rcu_set; 479 480 if (unlikely(!s) || !kasan_check_byte(s)) 481 return; 482 483 cpus_read_lock(); 484 mutex_lock(&slab_mutex); 485 486 rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; 487 488 refcnt = --s->refcount; 489 if (refcnt) 490 goto out_unlock; 491 492 WARN(shutdown_cache(s), 493 "%s %s: Slab cache still has objects when called from %pS", 494 __func__, s->name, (void *)_RET_IP_); 495 out_unlock: 496 mutex_unlock(&slab_mutex); 497 cpus_read_unlock(); 498 if (!refcnt && !rcu_set) 499 kmem_cache_release(s); 500 } 501 EXPORT_SYMBOL(kmem_cache_destroy); 502 503 /** 504 * kmem_cache_shrink - Shrink a cache. 505 * @cachep: The cache to shrink. 506 * 507 * Releases as many slabs as possible for a cache. 508 * To help debugging, a zero exit status indicates all slabs were released. 509 * 510 * Return: %0 if all slabs were released, non-zero otherwise 511 */ 512 int kmem_cache_shrink(struct kmem_cache *cachep) 513 { 514 kasan_cache_shrink(cachep); 515 516 return __kmem_cache_shrink(cachep); 517 } 518 EXPORT_SYMBOL(kmem_cache_shrink); 519 520 bool slab_is_available(void) 521 { 522 return slab_state >= UP; 523 } 524 525 #ifdef CONFIG_PRINTK 526 /** 527 * kmem_valid_obj - does the pointer reference a valid slab object? 528 * @object: pointer to query. 529 * 530 * Return: %true if the pointer is to a not-yet-freed object from 531 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 532 * is to an already-freed object, and %false otherwise. 533 */ 534 bool kmem_valid_obj(void *object) 535 { 536 struct folio *folio; 537 538 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 539 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 540 return false; 541 folio = virt_to_folio(object); 542 return folio_test_slab(folio); 543 } 544 EXPORT_SYMBOL_GPL(kmem_valid_obj); 545 546 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 547 { 548 if (__kfence_obj_info(kpp, object, slab)) 549 return; 550 __kmem_obj_info(kpp, object, slab); 551 } 552 553 /** 554 * kmem_dump_obj - Print available slab provenance information 555 * @object: slab object for which to find provenance information. 556 * 557 * This function uses pr_cont(), so that the caller is expected to have 558 * printed out whatever preamble is appropriate. The provenance information 559 * depends on the type of object and on how much debugging is enabled. 560 * For a slab-cache object, the fact that it is a slab object is printed, 561 * and, if available, the slab name, return address, and stack trace from 562 * the allocation and last free path of that object. 563 * 564 * This function will splat if passed a pointer to a non-slab object. 565 * If you are not sure what type of object you have, you should instead 566 * use mem_dump_obj(). 567 */ 568 void kmem_dump_obj(void *object) 569 { 570 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 571 int i; 572 struct slab *slab; 573 unsigned long ptroffset; 574 struct kmem_obj_info kp = { }; 575 576 if (WARN_ON_ONCE(!virt_addr_valid(object))) 577 return; 578 slab = virt_to_slab(object); 579 if (WARN_ON_ONCE(!slab)) { 580 pr_cont(" non-slab memory.\n"); 581 return; 582 } 583 kmem_obj_info(&kp, object, slab); 584 if (kp.kp_slab_cache) 585 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 586 else 587 pr_cont(" slab%s", cp); 588 if (is_kfence_address(object)) 589 pr_cont(" (kfence)"); 590 if (kp.kp_objp) 591 pr_cont(" start %px", kp.kp_objp); 592 if (kp.kp_data_offset) 593 pr_cont(" data offset %lu", kp.kp_data_offset); 594 if (kp.kp_objp) { 595 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 596 pr_cont(" pointer offset %lu", ptroffset); 597 } 598 if (kp.kp_slab_cache && kp.kp_slab_cache->usersize) 599 pr_cont(" size %u", kp.kp_slab_cache->usersize); 600 if (kp.kp_ret) 601 pr_cont(" allocated at %pS\n", kp.kp_ret); 602 else 603 pr_cont("\n"); 604 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 605 if (!kp.kp_stack[i]) 606 break; 607 pr_info(" %pS\n", kp.kp_stack[i]); 608 } 609 610 if (kp.kp_free_stack[0]) 611 pr_cont(" Free path:\n"); 612 613 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 614 if (!kp.kp_free_stack[i]) 615 break; 616 pr_info(" %pS\n", kp.kp_free_stack[i]); 617 } 618 619 } 620 EXPORT_SYMBOL_GPL(kmem_dump_obj); 621 #endif 622 623 #ifndef CONFIG_SLOB 624 /* Create a cache during boot when no slab services are available yet */ 625 void __init create_boot_cache(struct kmem_cache *s, const char *name, 626 unsigned int size, slab_flags_t flags, 627 unsigned int useroffset, unsigned int usersize) 628 { 629 int err; 630 unsigned int align = ARCH_KMALLOC_MINALIGN; 631 632 s->name = name; 633 s->size = s->object_size = size; 634 635 /* 636 * For power of two sizes, guarantee natural alignment for kmalloc 637 * caches, regardless of SL*B debugging options. 638 */ 639 if (is_power_of_2(size)) 640 align = max(align, size); 641 s->align = calculate_alignment(flags, align, size); 642 643 s->useroffset = useroffset; 644 s->usersize = usersize; 645 646 err = __kmem_cache_create(s, flags); 647 648 if (err) 649 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 650 name, size, err); 651 652 s->refcount = -1; /* Exempt from merging for now */ 653 } 654 655 struct kmem_cache *__init create_kmalloc_cache(const char *name, 656 unsigned int size, slab_flags_t flags, 657 unsigned int useroffset, unsigned int usersize) 658 { 659 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 660 661 if (!s) 662 panic("Out of memory when creating slab %s\n", name); 663 664 create_boot_cache(s, name, size, flags | SLAB_KMALLOC, useroffset, 665 usersize); 666 kasan_cache_create_kmalloc(s); 667 list_add(&s->list, &slab_caches); 668 s->refcount = 1; 669 return s; 670 } 671 672 struct kmem_cache * 673 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 674 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 675 EXPORT_SYMBOL(kmalloc_caches); 676 677 /* 678 * Conversion table for small slabs sizes / 8 to the index in the 679 * kmalloc array. This is necessary for slabs < 192 since we have non power 680 * of two cache sizes there. The size of larger slabs can be determined using 681 * fls. 682 */ 683 static u8 size_index[24] __ro_after_init = { 684 3, /* 8 */ 685 4, /* 16 */ 686 5, /* 24 */ 687 5, /* 32 */ 688 6, /* 40 */ 689 6, /* 48 */ 690 6, /* 56 */ 691 6, /* 64 */ 692 1, /* 72 */ 693 1, /* 80 */ 694 1, /* 88 */ 695 1, /* 96 */ 696 7, /* 104 */ 697 7, /* 112 */ 698 7, /* 120 */ 699 7, /* 128 */ 700 2, /* 136 */ 701 2, /* 144 */ 702 2, /* 152 */ 703 2, /* 160 */ 704 2, /* 168 */ 705 2, /* 176 */ 706 2, /* 184 */ 707 2 /* 192 */ 708 }; 709 710 static inline unsigned int size_index_elem(unsigned int bytes) 711 { 712 return (bytes - 1) / 8; 713 } 714 715 /* 716 * Find the kmem_cache structure that serves a given size of 717 * allocation 718 */ 719 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 720 { 721 unsigned int index; 722 723 if (size <= 192) { 724 if (!size) 725 return ZERO_SIZE_PTR; 726 727 index = size_index[size_index_elem(size)]; 728 } else { 729 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 730 return NULL; 731 index = fls(size - 1); 732 } 733 734 return kmalloc_caches[kmalloc_type(flags)][index]; 735 } 736 737 size_t kmalloc_size_roundup(size_t size) 738 { 739 struct kmem_cache *c; 740 741 /* Short-circuit the 0 size case. */ 742 if (unlikely(size == 0)) 743 return 0; 744 /* Short-circuit saturated "too-large" case. */ 745 if (unlikely(size == SIZE_MAX)) 746 return SIZE_MAX; 747 /* Above the smaller buckets, size is a multiple of page size. */ 748 if (size > KMALLOC_MAX_CACHE_SIZE) 749 return PAGE_SIZE << get_order(size); 750 751 /* The flags don't matter since size_index is common to all. */ 752 c = kmalloc_slab(size, GFP_KERNEL); 753 return c ? c->object_size : 0; 754 } 755 EXPORT_SYMBOL(kmalloc_size_roundup); 756 757 #ifdef CONFIG_ZONE_DMA 758 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 759 #else 760 #define KMALLOC_DMA_NAME(sz) 761 #endif 762 763 #ifdef CONFIG_MEMCG_KMEM 764 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 765 #else 766 #define KMALLOC_CGROUP_NAME(sz) 767 #endif 768 769 #define INIT_KMALLOC_INFO(__size, __short_size) \ 770 { \ 771 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 772 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 773 KMALLOC_CGROUP_NAME(__short_size) \ 774 KMALLOC_DMA_NAME(__short_size) \ 775 .size = __size, \ 776 } 777 778 /* 779 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 780 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is 781 * kmalloc-2M. 782 */ 783 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 784 INIT_KMALLOC_INFO(0, 0), 785 INIT_KMALLOC_INFO(96, 96), 786 INIT_KMALLOC_INFO(192, 192), 787 INIT_KMALLOC_INFO(8, 8), 788 INIT_KMALLOC_INFO(16, 16), 789 INIT_KMALLOC_INFO(32, 32), 790 INIT_KMALLOC_INFO(64, 64), 791 INIT_KMALLOC_INFO(128, 128), 792 INIT_KMALLOC_INFO(256, 256), 793 INIT_KMALLOC_INFO(512, 512), 794 INIT_KMALLOC_INFO(1024, 1k), 795 INIT_KMALLOC_INFO(2048, 2k), 796 INIT_KMALLOC_INFO(4096, 4k), 797 INIT_KMALLOC_INFO(8192, 8k), 798 INIT_KMALLOC_INFO(16384, 16k), 799 INIT_KMALLOC_INFO(32768, 32k), 800 INIT_KMALLOC_INFO(65536, 64k), 801 INIT_KMALLOC_INFO(131072, 128k), 802 INIT_KMALLOC_INFO(262144, 256k), 803 INIT_KMALLOC_INFO(524288, 512k), 804 INIT_KMALLOC_INFO(1048576, 1M), 805 INIT_KMALLOC_INFO(2097152, 2M) 806 }; 807 808 /* 809 * Patch up the size_index table if we have strange large alignment 810 * requirements for the kmalloc array. This is only the case for 811 * MIPS it seems. The standard arches will not generate any code here. 812 * 813 * Largest permitted alignment is 256 bytes due to the way we 814 * handle the index determination for the smaller caches. 815 * 816 * Make sure that nothing crazy happens if someone starts tinkering 817 * around with ARCH_KMALLOC_MINALIGN 818 */ 819 void __init setup_kmalloc_cache_index_table(void) 820 { 821 unsigned int i; 822 823 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 824 !is_power_of_2(KMALLOC_MIN_SIZE)); 825 826 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 827 unsigned int elem = size_index_elem(i); 828 829 if (elem >= ARRAY_SIZE(size_index)) 830 break; 831 size_index[elem] = KMALLOC_SHIFT_LOW; 832 } 833 834 if (KMALLOC_MIN_SIZE >= 64) { 835 /* 836 * The 96 byte sized cache is not used if the alignment 837 * is 64 byte. 838 */ 839 for (i = 64 + 8; i <= 96; i += 8) 840 size_index[size_index_elem(i)] = 7; 841 842 } 843 844 if (KMALLOC_MIN_SIZE >= 128) { 845 /* 846 * The 192 byte sized cache is not used if the alignment 847 * is 128 byte. Redirect kmalloc to use the 256 byte cache 848 * instead. 849 */ 850 for (i = 128 + 8; i <= 192; i += 8) 851 size_index[size_index_elem(i)] = 8; 852 } 853 } 854 855 static void __init 856 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 857 { 858 if (type == KMALLOC_RECLAIM) { 859 flags |= SLAB_RECLAIM_ACCOUNT; 860 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 861 if (mem_cgroup_kmem_disabled()) { 862 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 863 return; 864 } 865 flags |= SLAB_ACCOUNT; 866 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 867 flags |= SLAB_CACHE_DMA; 868 } 869 870 kmalloc_caches[type][idx] = create_kmalloc_cache( 871 kmalloc_info[idx].name[type], 872 kmalloc_info[idx].size, flags, 0, 873 kmalloc_info[idx].size); 874 875 /* 876 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 877 * KMALLOC_NORMAL caches. 878 */ 879 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 880 kmalloc_caches[type][idx]->refcount = -1; 881 } 882 883 /* 884 * Create the kmalloc array. Some of the regular kmalloc arrays 885 * may already have been created because they were needed to 886 * enable allocations for slab creation. 887 */ 888 void __init create_kmalloc_caches(slab_flags_t flags) 889 { 890 int i; 891 enum kmalloc_cache_type type; 892 893 /* 894 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 895 */ 896 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 897 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 898 if (!kmalloc_caches[type][i]) 899 new_kmalloc_cache(i, type, flags); 900 901 /* 902 * Caches that are not of the two-to-the-power-of size. 903 * These have to be created immediately after the 904 * earlier power of two caches 905 */ 906 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 907 !kmalloc_caches[type][1]) 908 new_kmalloc_cache(1, type, flags); 909 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 910 !kmalloc_caches[type][2]) 911 new_kmalloc_cache(2, type, flags); 912 } 913 } 914 915 /* Kmalloc array is now usable */ 916 slab_state = UP; 917 } 918 919 void free_large_kmalloc(struct folio *folio, void *object) 920 { 921 unsigned int order = folio_order(folio); 922 923 if (WARN_ON_ONCE(order == 0)) 924 pr_warn_once("object pointer: 0x%p\n", object); 925 926 kmemleak_free(object); 927 kasan_kfree_large(object); 928 kmsan_kfree_large(object); 929 930 mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B, 931 -(PAGE_SIZE << order)); 932 __free_pages(folio_page(folio, 0), order); 933 } 934 935 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node); 936 static __always_inline 937 void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) 938 { 939 struct kmem_cache *s; 940 void *ret; 941 942 if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { 943 ret = __kmalloc_large_node(size, flags, node); 944 trace_kmalloc(_RET_IP_, ret, size, 945 PAGE_SIZE << get_order(size), flags, node); 946 return ret; 947 } 948 949 s = kmalloc_slab(size, flags); 950 951 if (unlikely(ZERO_OR_NULL_PTR(s))) 952 return s; 953 954 ret = __kmem_cache_alloc_node(s, flags, node, size, caller); 955 ret = kasan_kmalloc(s, ret, size, flags); 956 trace_kmalloc(_RET_IP_, ret, size, s->size, flags, node); 957 return ret; 958 } 959 960 void *__kmalloc_node(size_t size, gfp_t flags, int node) 961 { 962 return __do_kmalloc_node(size, flags, node, _RET_IP_); 963 } 964 EXPORT_SYMBOL(__kmalloc_node); 965 966 void *__kmalloc(size_t size, gfp_t flags) 967 { 968 return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_); 969 } 970 EXPORT_SYMBOL(__kmalloc); 971 972 void *__kmalloc_node_track_caller(size_t size, gfp_t flags, 973 int node, unsigned long caller) 974 { 975 return __do_kmalloc_node(size, flags, node, caller); 976 } 977 EXPORT_SYMBOL(__kmalloc_node_track_caller); 978 979 /** 980 * kfree - free previously allocated memory 981 * @object: pointer returned by kmalloc. 982 * 983 * If @object is NULL, no operation is performed. 984 * 985 * Don't free memory not originally allocated by kmalloc() 986 * or you will run into trouble. 987 */ 988 void kfree(const void *object) 989 { 990 struct folio *folio; 991 struct slab *slab; 992 struct kmem_cache *s; 993 994 trace_kfree(_RET_IP_, object); 995 996 if (unlikely(ZERO_OR_NULL_PTR(object))) 997 return; 998 999 folio = virt_to_folio(object); 1000 if (unlikely(!folio_test_slab(folio))) { 1001 free_large_kmalloc(folio, (void *)object); 1002 return; 1003 } 1004 1005 slab = folio_slab(folio); 1006 s = slab->slab_cache; 1007 __kmem_cache_free(s, (void *)object, _RET_IP_); 1008 } 1009 EXPORT_SYMBOL(kfree); 1010 1011 /** 1012 * __ksize -- Report full size of underlying allocation 1013 * @objp: pointer to the object 1014 * 1015 * This should only be used internally to query the true size of allocations. 1016 * It is not meant to be a way to discover the usable size of an allocation 1017 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond 1018 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS, 1019 * and/or FORTIFY_SOURCE. 1020 * 1021 * Return: size of the actual memory used by @objp in bytes 1022 */ 1023 size_t __ksize(const void *object) 1024 { 1025 struct folio *folio; 1026 1027 if (unlikely(object == ZERO_SIZE_PTR)) 1028 return 0; 1029 1030 folio = virt_to_folio(object); 1031 1032 if (unlikely(!folio_test_slab(folio))) { 1033 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) 1034 return 0; 1035 if (WARN_ON(object != folio_address(folio))) 1036 return 0; 1037 return folio_size(folio); 1038 } 1039 1040 return slab_ksize(folio_slab(folio)->slab_cache); 1041 } 1042 1043 #ifdef CONFIG_TRACING 1044 void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) 1045 { 1046 void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE, 1047 size, _RET_IP_); 1048 1049 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE); 1050 1051 ret = kasan_kmalloc(s, ret, size, gfpflags); 1052 return ret; 1053 } 1054 EXPORT_SYMBOL(kmalloc_trace); 1055 1056 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, 1057 int node, size_t size) 1058 { 1059 void *ret = __kmem_cache_alloc_node(s, gfpflags, node, size, _RET_IP_); 1060 1061 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node); 1062 1063 ret = kasan_kmalloc(s, ret, size, gfpflags); 1064 return ret; 1065 } 1066 EXPORT_SYMBOL(kmalloc_node_trace); 1067 #endif /* !CONFIG_TRACING */ 1068 #endif /* !CONFIG_SLOB */ 1069 1070 gfp_t kmalloc_fix_flags(gfp_t flags) 1071 { 1072 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 1073 1074 flags &= ~GFP_SLAB_BUG_MASK; 1075 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 1076 invalid_mask, &invalid_mask, flags, &flags); 1077 dump_stack(); 1078 1079 return flags; 1080 } 1081 1082 /* 1083 * To avoid unnecessary overhead, we pass through large allocation requests 1084 * directly to the page allocator. We use __GFP_COMP, because we will need to 1085 * know the allocation order to free the pages properly in kfree. 1086 */ 1087 1088 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node) 1089 { 1090 struct page *page; 1091 void *ptr = NULL; 1092 unsigned int order = get_order(size); 1093 1094 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 1095 flags = kmalloc_fix_flags(flags); 1096 1097 flags |= __GFP_COMP; 1098 page = alloc_pages_node(node, flags, order); 1099 if (page) { 1100 ptr = page_address(page); 1101 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 1102 PAGE_SIZE << order); 1103 } 1104 1105 ptr = kasan_kmalloc_large(ptr, size, flags); 1106 /* As ptr might get tagged, call kmemleak hook after KASAN. */ 1107 kmemleak_alloc(ptr, size, 1, flags); 1108 kmsan_kmalloc_large(ptr, size, flags); 1109 1110 return ptr; 1111 } 1112 1113 void *kmalloc_large(size_t size, gfp_t flags) 1114 { 1115 void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE); 1116 1117 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1118 flags, NUMA_NO_NODE); 1119 return ret; 1120 } 1121 EXPORT_SYMBOL(kmalloc_large); 1122 1123 void *kmalloc_large_node(size_t size, gfp_t flags, int node) 1124 { 1125 void *ret = __kmalloc_large_node(size, flags, node); 1126 1127 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1128 flags, node); 1129 return ret; 1130 } 1131 EXPORT_SYMBOL(kmalloc_large_node); 1132 1133 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1134 /* Randomize a generic freelist */ 1135 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 1136 unsigned int count) 1137 { 1138 unsigned int rand; 1139 unsigned int i; 1140 1141 for (i = 0; i < count; i++) 1142 list[i] = i; 1143 1144 /* Fisher-Yates shuffle */ 1145 for (i = count - 1; i > 0; i--) { 1146 rand = prandom_u32_state(state); 1147 rand %= (i + 1); 1148 swap(list[i], list[rand]); 1149 } 1150 } 1151 1152 /* Create a random sequence per cache */ 1153 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1154 gfp_t gfp) 1155 { 1156 struct rnd_state state; 1157 1158 if (count < 2 || cachep->random_seq) 1159 return 0; 1160 1161 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1162 if (!cachep->random_seq) 1163 return -ENOMEM; 1164 1165 /* Get best entropy at this stage of boot */ 1166 prandom_seed_state(&state, get_random_long()); 1167 1168 freelist_randomize(&state, cachep->random_seq, count); 1169 return 0; 1170 } 1171 1172 /* Destroy the per-cache random freelist sequence */ 1173 void cache_random_seq_destroy(struct kmem_cache *cachep) 1174 { 1175 kfree(cachep->random_seq); 1176 cachep->random_seq = NULL; 1177 } 1178 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1179 1180 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 1181 #ifdef CONFIG_SLAB 1182 #define SLABINFO_RIGHTS (0600) 1183 #else 1184 #define SLABINFO_RIGHTS (0400) 1185 #endif 1186 1187 static void print_slabinfo_header(struct seq_file *m) 1188 { 1189 /* 1190 * Output format version, so at least we can change it 1191 * without _too_ many complaints. 1192 */ 1193 #ifdef CONFIG_DEBUG_SLAB 1194 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1195 #else 1196 seq_puts(m, "slabinfo - version: 2.1\n"); 1197 #endif 1198 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1199 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1200 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1201 #ifdef CONFIG_DEBUG_SLAB 1202 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1203 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1204 #endif 1205 seq_putc(m, '\n'); 1206 } 1207 1208 static void *slab_start(struct seq_file *m, loff_t *pos) 1209 { 1210 mutex_lock(&slab_mutex); 1211 return seq_list_start(&slab_caches, *pos); 1212 } 1213 1214 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1215 { 1216 return seq_list_next(p, &slab_caches, pos); 1217 } 1218 1219 static void slab_stop(struct seq_file *m, void *p) 1220 { 1221 mutex_unlock(&slab_mutex); 1222 } 1223 1224 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1225 { 1226 struct slabinfo sinfo; 1227 1228 memset(&sinfo, 0, sizeof(sinfo)); 1229 get_slabinfo(s, &sinfo); 1230 1231 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1232 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1233 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1234 1235 seq_printf(m, " : tunables %4u %4u %4u", 1236 sinfo.limit, sinfo.batchcount, sinfo.shared); 1237 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1238 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1239 slabinfo_show_stats(m, s); 1240 seq_putc(m, '\n'); 1241 } 1242 1243 static int slab_show(struct seq_file *m, void *p) 1244 { 1245 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1246 1247 if (p == slab_caches.next) 1248 print_slabinfo_header(m); 1249 cache_show(s, m); 1250 return 0; 1251 } 1252 1253 void dump_unreclaimable_slab(void) 1254 { 1255 struct kmem_cache *s; 1256 struct slabinfo sinfo; 1257 1258 /* 1259 * Here acquiring slab_mutex is risky since we don't prefer to get 1260 * sleep in oom path. But, without mutex hold, it may introduce a 1261 * risk of crash. 1262 * Use mutex_trylock to protect the list traverse, dump nothing 1263 * without acquiring the mutex. 1264 */ 1265 if (!mutex_trylock(&slab_mutex)) { 1266 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1267 return; 1268 } 1269 1270 pr_info("Unreclaimable slab info:\n"); 1271 pr_info("Name Used Total\n"); 1272 1273 list_for_each_entry(s, &slab_caches, list) { 1274 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1275 continue; 1276 1277 get_slabinfo(s, &sinfo); 1278 1279 if (sinfo.num_objs > 0) 1280 pr_info("%-17s %10luKB %10luKB\n", s->name, 1281 (sinfo.active_objs * s->size) / 1024, 1282 (sinfo.num_objs * s->size) / 1024); 1283 } 1284 mutex_unlock(&slab_mutex); 1285 } 1286 1287 /* 1288 * slabinfo_op - iterator that generates /proc/slabinfo 1289 * 1290 * Output layout: 1291 * cache-name 1292 * num-active-objs 1293 * total-objs 1294 * object size 1295 * num-active-slabs 1296 * total-slabs 1297 * num-pages-per-slab 1298 * + further values on SMP and with statistics enabled 1299 */ 1300 static const struct seq_operations slabinfo_op = { 1301 .start = slab_start, 1302 .next = slab_next, 1303 .stop = slab_stop, 1304 .show = slab_show, 1305 }; 1306 1307 static int slabinfo_open(struct inode *inode, struct file *file) 1308 { 1309 return seq_open(file, &slabinfo_op); 1310 } 1311 1312 static const struct proc_ops slabinfo_proc_ops = { 1313 .proc_flags = PROC_ENTRY_PERMANENT, 1314 .proc_open = slabinfo_open, 1315 .proc_read = seq_read, 1316 .proc_write = slabinfo_write, 1317 .proc_lseek = seq_lseek, 1318 .proc_release = seq_release, 1319 }; 1320 1321 static int __init slab_proc_init(void) 1322 { 1323 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1324 return 0; 1325 } 1326 module_init(slab_proc_init); 1327 1328 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1329 1330 static __always_inline __realloc_size(2) void * 1331 __do_krealloc(const void *p, size_t new_size, gfp_t flags) 1332 { 1333 void *ret; 1334 size_t ks; 1335 1336 /* Don't use instrumented ksize to allow precise KASAN poisoning. */ 1337 if (likely(!ZERO_OR_NULL_PTR(p))) { 1338 if (!kasan_check_byte(p)) 1339 return NULL; 1340 ks = kfence_ksize(p) ?: __ksize(p); 1341 } else 1342 ks = 0; 1343 1344 /* If the object still fits, repoison it precisely. */ 1345 if (ks >= new_size) { 1346 p = kasan_krealloc((void *)p, new_size, flags); 1347 return (void *)p; 1348 } 1349 1350 ret = kmalloc_track_caller(new_size, flags); 1351 if (ret && p) { 1352 /* Disable KASAN checks as the object's redzone is accessed. */ 1353 kasan_disable_current(); 1354 memcpy(ret, kasan_reset_tag(p), ks); 1355 kasan_enable_current(); 1356 } 1357 1358 return ret; 1359 } 1360 1361 /** 1362 * krealloc - reallocate memory. The contents will remain unchanged. 1363 * @p: object to reallocate memory for. 1364 * @new_size: how many bytes of memory are required. 1365 * @flags: the type of memory to allocate. 1366 * 1367 * The contents of the object pointed to are preserved up to the 1368 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1369 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1370 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1371 * 1372 * Return: pointer to the allocated memory or %NULL in case of error 1373 */ 1374 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1375 { 1376 void *ret; 1377 1378 if (unlikely(!new_size)) { 1379 kfree(p); 1380 return ZERO_SIZE_PTR; 1381 } 1382 1383 ret = __do_krealloc(p, new_size, flags); 1384 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1385 kfree(p); 1386 1387 return ret; 1388 } 1389 EXPORT_SYMBOL(krealloc); 1390 1391 /** 1392 * kfree_sensitive - Clear sensitive information in memory before freeing 1393 * @p: object to free memory of 1394 * 1395 * The memory of the object @p points to is zeroed before freed. 1396 * If @p is %NULL, kfree_sensitive() does nothing. 1397 * 1398 * Note: this function zeroes the whole allocated buffer which can be a good 1399 * deal bigger than the requested buffer size passed to kmalloc(). So be 1400 * careful when using this function in performance sensitive code. 1401 */ 1402 void kfree_sensitive(const void *p) 1403 { 1404 size_t ks; 1405 void *mem = (void *)p; 1406 1407 ks = ksize(mem); 1408 if (ks) 1409 memzero_explicit(mem, ks); 1410 kfree(mem); 1411 } 1412 EXPORT_SYMBOL(kfree_sensitive); 1413 1414 /** 1415 * ksize - get the actual amount of memory allocated for a given object 1416 * @objp: Pointer to the object 1417 * 1418 * kmalloc may internally round up allocations and return more memory 1419 * than requested. ksize() can be used to determine the actual amount of 1420 * memory allocated. The caller may use this additional memory, even though 1421 * a smaller amount of memory was initially specified with the kmalloc call. 1422 * The caller must guarantee that objp points to a valid object previously 1423 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1424 * must not be freed during the duration of the call. 1425 * 1426 * Return: size of the actual memory used by @objp in bytes 1427 */ 1428 size_t ksize(const void *objp) 1429 { 1430 size_t size; 1431 1432 /* 1433 * We need to first check that the pointer to the object is valid, and 1434 * only then unpoison the memory. The report printed from ksize() is 1435 * more useful, then when it's printed later when the behaviour could 1436 * be undefined due to a potential use-after-free or double-free. 1437 * 1438 * We use kasan_check_byte(), which is supported for the hardware 1439 * tag-based KASAN mode, unlike kasan_check_read/write(). 1440 * 1441 * If the pointed to memory is invalid, we return 0 to avoid users of 1442 * ksize() writing to and potentially corrupting the memory region. 1443 * 1444 * We want to perform the check before __ksize(), to avoid potentially 1445 * crashing in __ksize() due to accessing invalid metadata. 1446 */ 1447 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1448 return 0; 1449 1450 size = kfence_ksize(objp) ?: __ksize(objp); 1451 /* 1452 * We assume that ksize callers could use whole allocated area, 1453 * so we need to unpoison this area. 1454 */ 1455 kasan_unpoison_range(objp, size); 1456 return size; 1457 } 1458 EXPORT_SYMBOL(ksize); 1459 1460 /* Tracepoints definitions. */ 1461 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1462 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1463 EXPORT_TRACEPOINT_SYMBOL(kfree); 1464 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1465 1466 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1467 { 1468 if (__should_failslab(s, gfpflags)) 1469 return -ENOMEM; 1470 return 0; 1471 } 1472 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1473