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/dma-mapping.h> 21 #include <linux/swiotlb.h> 22 #include <linux/proc_fs.h> 23 #include <linux/debugfs.h> 24 #include <linux/kasan.h> 25 #include <asm/cacheflush.h> 26 #include <asm/tlbflush.h> 27 #include <asm/page.h> 28 #include <linux/memcontrol.h> 29 #include <linux/stackdepot.h> 30 31 #include "internal.h" 32 #include "slab.h" 33 34 #define CREATE_TRACE_POINTS 35 #include <trace/events/kmem.h> 36 37 enum slab_state slab_state; 38 LIST_HEAD(slab_caches); 39 DEFINE_MUTEX(slab_mutex); 40 struct kmem_cache *kmem_cache; 41 42 static LIST_HEAD(slab_caches_to_rcu_destroy); 43 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 44 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 45 slab_caches_to_rcu_destroy_workfn); 46 47 /* 48 * Set of flags that will prevent slab merging 49 */ 50 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 51 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 52 SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge()) 53 54 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 55 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 56 57 /* 58 * Merge control. If this is set then no merging of slab caches will occur. 59 */ 60 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 61 62 static int __init setup_slab_nomerge(char *str) 63 { 64 slab_nomerge = true; 65 return 1; 66 } 67 68 static int __init setup_slab_merge(char *str) 69 { 70 slab_nomerge = false; 71 return 1; 72 } 73 74 #ifdef CONFIG_SLUB 75 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 76 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0); 77 #endif 78 79 __setup("slab_nomerge", setup_slab_nomerge); 80 __setup("slab_merge", setup_slab_merge); 81 82 /* 83 * Determine the size of a slab object 84 */ 85 unsigned int kmem_cache_size(struct kmem_cache *s) 86 { 87 return s->object_size; 88 } 89 EXPORT_SYMBOL(kmem_cache_size); 90 91 #ifdef CONFIG_DEBUG_VM 92 static int kmem_cache_sanity_check(const char *name, unsigned int size) 93 { 94 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { 95 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 96 return -EINVAL; 97 } 98 99 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 100 return 0; 101 } 102 #else 103 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 104 { 105 return 0; 106 } 107 #endif 108 109 /* 110 * Figure out what the alignment of the objects will be given a set of 111 * flags, a user specified alignment and the size of the objects. 112 */ 113 static unsigned int calculate_alignment(slab_flags_t flags, 114 unsigned int align, unsigned int size) 115 { 116 /* 117 * If the user wants hardware cache aligned objects then follow that 118 * suggestion if the object is sufficiently large. 119 * 120 * The hardware cache alignment cannot override the specified 121 * alignment though. If that is greater then use it. 122 */ 123 if (flags & SLAB_HWCACHE_ALIGN) { 124 unsigned int ralign; 125 126 ralign = cache_line_size(); 127 while (size <= ralign / 2) 128 ralign /= 2; 129 align = max(align, ralign); 130 } 131 132 align = max(align, arch_slab_minalign()); 133 134 return ALIGN(align, sizeof(void *)); 135 } 136 137 /* 138 * Find a mergeable slab cache 139 */ 140 int slab_unmergeable(struct kmem_cache *s) 141 { 142 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 143 return 1; 144 145 if (s->ctor) 146 return 1; 147 148 #ifdef CONFIG_HARDENED_USERCOPY 149 if (s->usersize) 150 return 1; 151 #endif 152 153 /* 154 * We may have set a slab to be unmergeable during bootstrap. 155 */ 156 if (s->refcount < 0) 157 return 1; 158 159 return 0; 160 } 161 162 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 163 slab_flags_t flags, const char *name, void (*ctor)(void *)) 164 { 165 struct kmem_cache *s; 166 167 if (slab_nomerge) 168 return NULL; 169 170 if (ctor) 171 return NULL; 172 173 size = ALIGN(size, sizeof(void *)); 174 align = calculate_alignment(flags, align, size); 175 size = ALIGN(size, align); 176 flags = kmem_cache_flags(size, flags, name); 177 178 if (flags & SLAB_NEVER_MERGE) 179 return NULL; 180 181 list_for_each_entry_reverse(s, &slab_caches, list) { 182 if (slab_unmergeable(s)) 183 continue; 184 185 if (size > s->size) 186 continue; 187 188 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 189 continue; 190 /* 191 * Check if alignment is compatible. 192 * Courtesy of Adrian Drzewiecki 193 */ 194 if ((s->size & ~(align - 1)) != s->size) 195 continue; 196 197 if (s->size - size >= sizeof(void *)) 198 continue; 199 200 if (IS_ENABLED(CONFIG_SLAB) && align && 201 (align > s->align || s->align % align)) 202 continue; 203 204 return s; 205 } 206 return NULL; 207 } 208 209 static struct kmem_cache *create_cache(const char *name, 210 unsigned int object_size, unsigned int align, 211 slab_flags_t flags, unsigned int useroffset, 212 unsigned int usersize, void (*ctor)(void *), 213 struct kmem_cache *root_cache) 214 { 215 struct kmem_cache *s; 216 int err; 217 218 if (WARN_ON(useroffset + usersize > object_size)) 219 useroffset = usersize = 0; 220 221 err = -ENOMEM; 222 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 223 if (!s) 224 goto out; 225 226 s->name = name; 227 s->size = s->object_size = object_size; 228 s->align = align; 229 s->ctor = ctor; 230 #ifdef CONFIG_HARDENED_USERCOPY 231 s->useroffset = useroffset; 232 s->usersize = usersize; 233 #endif 234 235 err = __kmem_cache_create(s, flags); 236 if (err) 237 goto out_free_cache; 238 239 s->refcount = 1; 240 list_add(&s->list, &slab_caches); 241 return s; 242 243 out_free_cache: 244 kmem_cache_free(kmem_cache, s); 245 out: 246 return ERR_PTR(err); 247 } 248 249 /** 250 * kmem_cache_create_usercopy - Create a cache with a region suitable 251 * for copying to userspace 252 * @name: A string which is used in /proc/slabinfo to identify this cache. 253 * @size: The size of objects to be created in this cache. 254 * @align: The required alignment for the objects. 255 * @flags: SLAB flags 256 * @useroffset: Usercopy region offset 257 * @usersize: Usercopy region size 258 * @ctor: A constructor for the objects. 259 * 260 * Cannot be called within a interrupt, but can be interrupted. 261 * The @ctor is run when new pages are allocated by the cache. 262 * 263 * The flags are 264 * 265 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 266 * to catch references to uninitialised memory. 267 * 268 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 269 * for buffer overruns. 270 * 271 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 272 * cacheline. This can be beneficial if you're counting cycles as closely 273 * as davem. 274 * 275 * Return: a pointer to the cache on success, NULL on failure. 276 */ 277 struct kmem_cache * 278 kmem_cache_create_usercopy(const char *name, 279 unsigned int size, unsigned int align, 280 slab_flags_t flags, 281 unsigned int useroffset, unsigned int usersize, 282 void (*ctor)(void *)) 283 { 284 struct kmem_cache *s = NULL; 285 const char *cache_name; 286 int err; 287 288 #ifdef CONFIG_SLUB_DEBUG 289 /* 290 * If no slub_debug was enabled globally, the static key is not yet 291 * enabled by setup_slub_debug(). Enable it if the cache is being 292 * created with any of the debugging flags passed explicitly. 293 * It's also possible that this is the first cache created with 294 * SLAB_STORE_USER and we should init stack_depot for it. 295 */ 296 if (flags & SLAB_DEBUG_FLAGS) 297 static_branch_enable(&slub_debug_enabled); 298 if (flags & SLAB_STORE_USER) 299 stack_depot_init(); 300 #endif 301 302 mutex_lock(&slab_mutex); 303 304 err = kmem_cache_sanity_check(name, size); 305 if (err) { 306 goto out_unlock; 307 } 308 309 /* Refuse requests with allocator specific flags */ 310 if (flags & ~SLAB_FLAGS_PERMITTED) { 311 err = -EINVAL; 312 goto out_unlock; 313 } 314 315 /* 316 * Some allocators will constraint the set of valid flags to a subset 317 * of all flags. We expect them to define CACHE_CREATE_MASK in this 318 * case, and we'll just provide them with a sanitized version of the 319 * passed flags. 320 */ 321 flags &= CACHE_CREATE_MASK; 322 323 /* Fail closed on bad usersize of useroffset values. */ 324 if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || 325 WARN_ON(!usersize && useroffset) || 326 WARN_ON(size < usersize || size - usersize < useroffset)) 327 usersize = useroffset = 0; 328 329 if (!usersize) 330 s = __kmem_cache_alias(name, size, align, flags, ctor); 331 if (s) 332 goto out_unlock; 333 334 cache_name = kstrdup_const(name, GFP_KERNEL); 335 if (!cache_name) { 336 err = -ENOMEM; 337 goto out_unlock; 338 } 339 340 s = create_cache(cache_name, size, 341 calculate_alignment(flags, align, size), 342 flags, useroffset, usersize, ctor, NULL); 343 if (IS_ERR(s)) { 344 err = PTR_ERR(s); 345 kfree_const(cache_name); 346 } 347 348 out_unlock: 349 mutex_unlock(&slab_mutex); 350 351 if (err) { 352 if (flags & SLAB_PANIC) 353 panic("%s: Failed to create slab '%s'. Error %d\n", 354 __func__, name, err); 355 else { 356 pr_warn("%s(%s) failed with error %d\n", 357 __func__, name, err); 358 dump_stack(); 359 } 360 return NULL; 361 } 362 return s; 363 } 364 EXPORT_SYMBOL(kmem_cache_create_usercopy); 365 366 /** 367 * kmem_cache_create - Create a cache. 368 * @name: A string which is used in /proc/slabinfo to identify this cache. 369 * @size: The size of objects to be created in this cache. 370 * @align: The required alignment for the objects. 371 * @flags: SLAB flags 372 * @ctor: A constructor for the objects. 373 * 374 * Cannot be called within a interrupt, but can be interrupted. 375 * The @ctor is run when new pages are allocated by the cache. 376 * 377 * The flags are 378 * 379 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 380 * to catch references to uninitialised memory. 381 * 382 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 383 * for buffer overruns. 384 * 385 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 386 * cacheline. This can be beneficial if you're counting cycles as closely 387 * as davem. 388 * 389 * Return: a pointer to the cache on success, NULL on failure. 390 */ 391 struct kmem_cache * 392 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 393 slab_flags_t flags, void (*ctor)(void *)) 394 { 395 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 396 ctor); 397 } 398 EXPORT_SYMBOL(kmem_cache_create); 399 400 #ifdef SLAB_SUPPORTS_SYSFS 401 /* 402 * For a given kmem_cache, kmem_cache_destroy() should only be called 403 * once or there will be a use-after-free problem. The actual deletion 404 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock 405 * protection. So they are now done without holding those locks. 406 * 407 * Note that there will be a slight delay in the deletion of sysfs files 408 * if kmem_cache_release() is called indrectly from a work function. 409 */ 410 static void kmem_cache_release(struct kmem_cache *s) 411 { 412 sysfs_slab_unlink(s); 413 sysfs_slab_release(s); 414 } 415 #else 416 static void kmem_cache_release(struct kmem_cache *s) 417 { 418 slab_kmem_cache_release(s); 419 } 420 #endif 421 422 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 423 { 424 LIST_HEAD(to_destroy); 425 struct kmem_cache *s, *s2; 426 427 /* 428 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 429 * @slab_caches_to_rcu_destroy list. The slab pages are freed 430 * through RCU and the associated kmem_cache are dereferenced 431 * while freeing the pages, so the kmem_caches should be freed only 432 * after the pending RCU operations are finished. As rcu_barrier() 433 * is a pretty slow operation, we batch all pending destructions 434 * asynchronously. 435 */ 436 mutex_lock(&slab_mutex); 437 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 438 mutex_unlock(&slab_mutex); 439 440 if (list_empty(&to_destroy)) 441 return; 442 443 rcu_barrier(); 444 445 list_for_each_entry_safe(s, s2, &to_destroy, list) { 446 debugfs_slab_release(s); 447 kfence_shutdown_cache(s); 448 kmem_cache_release(s); 449 } 450 } 451 452 static int shutdown_cache(struct kmem_cache *s) 453 { 454 /* free asan quarantined objects */ 455 kasan_cache_shutdown(s); 456 457 if (__kmem_cache_shutdown(s) != 0) 458 return -EBUSY; 459 460 list_del(&s->list); 461 462 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 463 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 464 schedule_work(&slab_caches_to_rcu_destroy_work); 465 } else { 466 kfence_shutdown_cache(s); 467 debugfs_slab_release(s); 468 } 469 470 return 0; 471 } 472 473 void slab_kmem_cache_release(struct kmem_cache *s) 474 { 475 __kmem_cache_release(s); 476 kfree_const(s->name); 477 kmem_cache_free(kmem_cache, s); 478 } 479 480 void kmem_cache_destroy(struct kmem_cache *s) 481 { 482 int refcnt; 483 bool rcu_set; 484 485 if (unlikely(!s) || !kasan_check_byte(s)) 486 return; 487 488 cpus_read_lock(); 489 mutex_lock(&slab_mutex); 490 491 rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; 492 493 refcnt = --s->refcount; 494 if (refcnt) 495 goto out_unlock; 496 497 WARN(shutdown_cache(s), 498 "%s %s: Slab cache still has objects when called from %pS", 499 __func__, s->name, (void *)_RET_IP_); 500 out_unlock: 501 mutex_unlock(&slab_mutex); 502 cpus_read_unlock(); 503 if (!refcnt && !rcu_set) 504 kmem_cache_release(s); 505 } 506 EXPORT_SYMBOL(kmem_cache_destroy); 507 508 /** 509 * kmem_cache_shrink - Shrink a cache. 510 * @cachep: The cache to shrink. 511 * 512 * Releases as many slabs as possible for a cache. 513 * To help debugging, a zero exit status indicates all slabs were released. 514 * 515 * Return: %0 if all slabs were released, non-zero otherwise 516 */ 517 int kmem_cache_shrink(struct kmem_cache *cachep) 518 { 519 kasan_cache_shrink(cachep); 520 521 return __kmem_cache_shrink(cachep); 522 } 523 EXPORT_SYMBOL(kmem_cache_shrink); 524 525 bool slab_is_available(void) 526 { 527 return slab_state >= UP; 528 } 529 530 #ifdef CONFIG_PRINTK 531 /** 532 * kmem_valid_obj - does the pointer reference a valid slab object? 533 * @object: pointer to query. 534 * 535 * Return: %true if the pointer is to a not-yet-freed object from 536 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 537 * is to an already-freed object, and %false otherwise. 538 */ 539 bool kmem_valid_obj(void *object) 540 { 541 struct folio *folio; 542 543 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 544 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 545 return false; 546 folio = virt_to_folio(object); 547 return folio_test_slab(folio); 548 } 549 EXPORT_SYMBOL_GPL(kmem_valid_obj); 550 551 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 552 { 553 if (__kfence_obj_info(kpp, object, slab)) 554 return; 555 __kmem_obj_info(kpp, object, slab); 556 } 557 558 /** 559 * kmem_dump_obj - Print available slab provenance information 560 * @object: slab object for which to find provenance information. 561 * 562 * This function uses pr_cont(), so that the caller is expected to have 563 * printed out whatever preamble is appropriate. The provenance information 564 * depends on the type of object and on how much debugging is enabled. 565 * For a slab-cache object, the fact that it is a slab object is printed, 566 * and, if available, the slab name, return address, and stack trace from 567 * the allocation and last free path of that object. 568 * 569 * This function will splat if passed a pointer to a non-slab object. 570 * If you are not sure what type of object you have, you should instead 571 * use mem_dump_obj(). 572 */ 573 void kmem_dump_obj(void *object) 574 { 575 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 576 int i; 577 struct slab *slab; 578 unsigned long ptroffset; 579 struct kmem_obj_info kp = { }; 580 581 if (WARN_ON_ONCE(!virt_addr_valid(object))) 582 return; 583 slab = virt_to_slab(object); 584 if (WARN_ON_ONCE(!slab)) { 585 pr_cont(" non-slab memory.\n"); 586 return; 587 } 588 kmem_obj_info(&kp, object, slab); 589 if (kp.kp_slab_cache) 590 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 591 else 592 pr_cont(" slab%s", cp); 593 if (is_kfence_address(object)) 594 pr_cont(" (kfence)"); 595 if (kp.kp_objp) 596 pr_cont(" start %px", kp.kp_objp); 597 if (kp.kp_data_offset) 598 pr_cont(" data offset %lu", kp.kp_data_offset); 599 if (kp.kp_objp) { 600 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 601 pr_cont(" pointer offset %lu", ptroffset); 602 } 603 if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) 604 pr_cont(" size %u", kp.kp_slab_cache->object_size); 605 if (kp.kp_ret) 606 pr_cont(" allocated at %pS\n", kp.kp_ret); 607 else 608 pr_cont("\n"); 609 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 610 if (!kp.kp_stack[i]) 611 break; 612 pr_info(" %pS\n", kp.kp_stack[i]); 613 } 614 615 if (kp.kp_free_stack[0]) 616 pr_cont(" Free path:\n"); 617 618 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 619 if (!kp.kp_free_stack[i]) 620 break; 621 pr_info(" %pS\n", kp.kp_free_stack[i]); 622 } 623 624 } 625 EXPORT_SYMBOL_GPL(kmem_dump_obj); 626 #endif 627 628 /* Create a cache during boot when no slab services are available yet */ 629 void __init create_boot_cache(struct kmem_cache *s, const char *name, 630 unsigned int size, slab_flags_t flags, 631 unsigned int useroffset, unsigned int usersize) 632 { 633 int err; 634 unsigned int align = ARCH_KMALLOC_MINALIGN; 635 636 s->name = name; 637 s->size = s->object_size = size; 638 639 /* 640 * For power of two sizes, guarantee natural alignment for kmalloc 641 * caches, regardless of SL*B debugging options. 642 */ 643 if (is_power_of_2(size)) 644 align = max(align, size); 645 s->align = calculate_alignment(flags, align, size); 646 647 #ifdef CONFIG_HARDENED_USERCOPY 648 s->useroffset = useroffset; 649 s->usersize = usersize; 650 #endif 651 652 err = __kmem_cache_create(s, flags); 653 654 if (err) 655 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 656 name, size, err); 657 658 s->refcount = -1; /* Exempt from merging for now */ 659 } 660 661 static struct kmem_cache *__init create_kmalloc_cache(const char *name, 662 unsigned int size, 663 slab_flags_t flags) 664 { 665 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 666 667 if (!s) 668 panic("Out of memory when creating slab %s\n", name); 669 670 create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size); 671 list_add(&s->list, &slab_caches); 672 s->refcount = 1; 673 return s; 674 } 675 676 struct kmem_cache * 677 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 678 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 679 EXPORT_SYMBOL(kmalloc_caches); 680 681 /* 682 * Conversion table for small slabs sizes / 8 to the index in the 683 * kmalloc array. This is necessary for slabs < 192 since we have non power 684 * of two cache sizes there. The size of larger slabs can be determined using 685 * fls. 686 */ 687 static u8 size_index[24] __ro_after_init = { 688 3, /* 8 */ 689 4, /* 16 */ 690 5, /* 24 */ 691 5, /* 32 */ 692 6, /* 40 */ 693 6, /* 48 */ 694 6, /* 56 */ 695 6, /* 64 */ 696 1, /* 72 */ 697 1, /* 80 */ 698 1, /* 88 */ 699 1, /* 96 */ 700 7, /* 104 */ 701 7, /* 112 */ 702 7, /* 120 */ 703 7, /* 128 */ 704 2, /* 136 */ 705 2, /* 144 */ 706 2, /* 152 */ 707 2, /* 160 */ 708 2, /* 168 */ 709 2, /* 176 */ 710 2, /* 184 */ 711 2 /* 192 */ 712 }; 713 714 static inline unsigned int size_index_elem(unsigned int bytes) 715 { 716 return (bytes - 1) / 8; 717 } 718 719 /* 720 * Find the kmem_cache structure that serves a given size of 721 * allocation 722 */ 723 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 724 { 725 unsigned int index; 726 727 if (size <= 192) { 728 if (!size) 729 return ZERO_SIZE_PTR; 730 731 index = size_index[size_index_elem(size)]; 732 } else { 733 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 734 return NULL; 735 index = fls(size - 1); 736 } 737 738 return kmalloc_caches[kmalloc_type(flags)][index]; 739 } 740 741 size_t kmalloc_size_roundup(size_t size) 742 { 743 struct kmem_cache *c; 744 745 /* Short-circuit the 0 size case. */ 746 if (unlikely(size == 0)) 747 return 0; 748 /* Short-circuit saturated "too-large" case. */ 749 if (unlikely(size == SIZE_MAX)) 750 return SIZE_MAX; 751 /* Above the smaller buckets, size is a multiple of page size. */ 752 if (size > KMALLOC_MAX_CACHE_SIZE) 753 return PAGE_SIZE << get_order(size); 754 755 /* The flags don't matter since size_index is common to all. */ 756 c = kmalloc_slab(size, GFP_KERNEL); 757 return c ? c->object_size : 0; 758 } 759 EXPORT_SYMBOL(kmalloc_size_roundup); 760 761 #ifdef CONFIG_ZONE_DMA 762 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 763 #else 764 #define KMALLOC_DMA_NAME(sz) 765 #endif 766 767 #ifdef CONFIG_MEMCG_KMEM 768 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 769 #else 770 #define KMALLOC_CGROUP_NAME(sz) 771 #endif 772 773 #ifndef CONFIG_SLUB_TINY 774 #define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz, 775 #else 776 #define KMALLOC_RCL_NAME(sz) 777 #endif 778 779 #define INIT_KMALLOC_INFO(__size, __short_size) \ 780 { \ 781 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 782 KMALLOC_RCL_NAME(__short_size) \ 783 KMALLOC_CGROUP_NAME(__short_size) \ 784 KMALLOC_DMA_NAME(__short_size) \ 785 .size = __size, \ 786 } 787 788 /* 789 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 790 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is 791 * kmalloc-2M. 792 */ 793 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 794 INIT_KMALLOC_INFO(0, 0), 795 INIT_KMALLOC_INFO(96, 96), 796 INIT_KMALLOC_INFO(192, 192), 797 INIT_KMALLOC_INFO(8, 8), 798 INIT_KMALLOC_INFO(16, 16), 799 INIT_KMALLOC_INFO(32, 32), 800 INIT_KMALLOC_INFO(64, 64), 801 INIT_KMALLOC_INFO(128, 128), 802 INIT_KMALLOC_INFO(256, 256), 803 INIT_KMALLOC_INFO(512, 512), 804 INIT_KMALLOC_INFO(1024, 1k), 805 INIT_KMALLOC_INFO(2048, 2k), 806 INIT_KMALLOC_INFO(4096, 4k), 807 INIT_KMALLOC_INFO(8192, 8k), 808 INIT_KMALLOC_INFO(16384, 16k), 809 INIT_KMALLOC_INFO(32768, 32k), 810 INIT_KMALLOC_INFO(65536, 64k), 811 INIT_KMALLOC_INFO(131072, 128k), 812 INIT_KMALLOC_INFO(262144, 256k), 813 INIT_KMALLOC_INFO(524288, 512k), 814 INIT_KMALLOC_INFO(1048576, 1M), 815 INIT_KMALLOC_INFO(2097152, 2M) 816 }; 817 818 /* 819 * Patch up the size_index table if we have strange large alignment 820 * requirements for the kmalloc array. This is only the case for 821 * MIPS it seems. The standard arches will not generate any code here. 822 * 823 * Largest permitted alignment is 256 bytes due to the way we 824 * handle the index determination for the smaller caches. 825 * 826 * Make sure that nothing crazy happens if someone starts tinkering 827 * around with ARCH_KMALLOC_MINALIGN 828 */ 829 void __init setup_kmalloc_cache_index_table(void) 830 { 831 unsigned int i; 832 833 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 834 !is_power_of_2(KMALLOC_MIN_SIZE)); 835 836 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 837 unsigned int elem = size_index_elem(i); 838 839 if (elem >= ARRAY_SIZE(size_index)) 840 break; 841 size_index[elem] = KMALLOC_SHIFT_LOW; 842 } 843 844 if (KMALLOC_MIN_SIZE >= 64) { 845 /* 846 * The 96 byte sized cache is not used if the alignment 847 * is 64 byte. 848 */ 849 for (i = 64 + 8; i <= 96; i += 8) 850 size_index[size_index_elem(i)] = 7; 851 852 } 853 854 if (KMALLOC_MIN_SIZE >= 128) { 855 /* 856 * The 192 byte sized cache is not used if the alignment 857 * is 128 byte. Redirect kmalloc to use the 256 byte cache 858 * instead. 859 */ 860 for (i = 128 + 8; i <= 192; i += 8) 861 size_index[size_index_elem(i)] = 8; 862 } 863 } 864 865 static unsigned int __kmalloc_minalign(void) 866 { 867 #ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC 868 if (io_tlb_default_mem.nslabs) 869 return ARCH_KMALLOC_MINALIGN; 870 #endif 871 return dma_get_cache_alignment(); 872 } 873 874 void __init 875 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 876 { 877 unsigned int minalign = __kmalloc_minalign(); 878 unsigned int aligned_size = kmalloc_info[idx].size; 879 int aligned_idx = idx; 880 881 if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) { 882 flags |= SLAB_RECLAIM_ACCOUNT; 883 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 884 if (mem_cgroup_kmem_disabled()) { 885 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 886 return; 887 } 888 flags |= SLAB_ACCOUNT; 889 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 890 flags |= SLAB_CACHE_DMA; 891 } 892 893 /* 894 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 895 * KMALLOC_NORMAL caches. 896 */ 897 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 898 flags |= SLAB_NO_MERGE; 899 900 if (minalign > ARCH_KMALLOC_MINALIGN) { 901 aligned_size = ALIGN(aligned_size, minalign); 902 aligned_idx = __kmalloc_index(aligned_size, false); 903 } 904 905 if (!kmalloc_caches[type][aligned_idx]) 906 kmalloc_caches[type][aligned_idx] = create_kmalloc_cache( 907 kmalloc_info[aligned_idx].name[type], 908 aligned_size, flags); 909 if (idx != aligned_idx) 910 kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx]; 911 } 912 913 /* 914 * Create the kmalloc array. Some of the regular kmalloc arrays 915 * may already have been created because they were needed to 916 * enable allocations for slab creation. 917 */ 918 void __init create_kmalloc_caches(slab_flags_t flags) 919 { 920 int i; 921 enum kmalloc_cache_type type; 922 923 /* 924 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 925 */ 926 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 927 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 928 if (!kmalloc_caches[type][i]) 929 new_kmalloc_cache(i, type, flags); 930 931 /* 932 * Caches that are not of the two-to-the-power-of size. 933 * These have to be created immediately after the 934 * earlier power of two caches 935 */ 936 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 937 !kmalloc_caches[type][1]) 938 new_kmalloc_cache(1, type, flags); 939 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 940 !kmalloc_caches[type][2]) 941 new_kmalloc_cache(2, type, flags); 942 } 943 } 944 945 /* Kmalloc array is now usable */ 946 slab_state = UP; 947 } 948 949 void free_large_kmalloc(struct folio *folio, void *object) 950 { 951 unsigned int order = folio_order(folio); 952 953 if (WARN_ON_ONCE(order == 0)) 954 pr_warn_once("object pointer: 0x%p\n", object); 955 956 kmemleak_free(object); 957 kasan_kfree_large(object); 958 kmsan_kfree_large(object); 959 960 mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B, 961 -(PAGE_SIZE << order)); 962 __free_pages(folio_page(folio, 0), order); 963 } 964 965 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node); 966 static __always_inline 967 void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) 968 { 969 struct kmem_cache *s; 970 void *ret; 971 972 if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { 973 ret = __kmalloc_large_node(size, flags, node); 974 trace_kmalloc(caller, ret, size, 975 PAGE_SIZE << get_order(size), flags, node); 976 return ret; 977 } 978 979 s = kmalloc_slab(size, flags); 980 981 if (unlikely(ZERO_OR_NULL_PTR(s))) 982 return s; 983 984 ret = __kmem_cache_alloc_node(s, flags, node, size, caller); 985 ret = kasan_kmalloc(s, ret, size, flags); 986 trace_kmalloc(caller, ret, size, s->size, flags, node); 987 return ret; 988 } 989 990 void *__kmalloc_node(size_t size, gfp_t flags, int node) 991 { 992 return __do_kmalloc_node(size, flags, node, _RET_IP_); 993 } 994 EXPORT_SYMBOL(__kmalloc_node); 995 996 void *__kmalloc(size_t size, gfp_t flags) 997 { 998 return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_); 999 } 1000 EXPORT_SYMBOL(__kmalloc); 1001 1002 void *__kmalloc_node_track_caller(size_t size, gfp_t flags, 1003 int node, unsigned long caller) 1004 { 1005 return __do_kmalloc_node(size, flags, node, caller); 1006 } 1007 EXPORT_SYMBOL(__kmalloc_node_track_caller); 1008 1009 /** 1010 * kfree - free previously allocated memory 1011 * @object: pointer returned by kmalloc() or kmem_cache_alloc() 1012 * 1013 * If @object is NULL, no operation is performed. 1014 */ 1015 void kfree(const void *object) 1016 { 1017 struct folio *folio; 1018 struct slab *slab; 1019 struct kmem_cache *s; 1020 1021 trace_kfree(_RET_IP_, object); 1022 1023 if (unlikely(ZERO_OR_NULL_PTR(object))) 1024 return; 1025 1026 folio = virt_to_folio(object); 1027 if (unlikely(!folio_test_slab(folio))) { 1028 free_large_kmalloc(folio, (void *)object); 1029 return; 1030 } 1031 1032 slab = folio_slab(folio); 1033 s = slab->slab_cache; 1034 __kmem_cache_free(s, (void *)object, _RET_IP_); 1035 } 1036 EXPORT_SYMBOL(kfree); 1037 1038 /** 1039 * __ksize -- Report full size of underlying allocation 1040 * @object: pointer to the object 1041 * 1042 * This should only be used internally to query the true size of allocations. 1043 * It is not meant to be a way to discover the usable size of an allocation 1044 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond 1045 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS, 1046 * and/or FORTIFY_SOURCE. 1047 * 1048 * Return: size of the actual memory used by @object in bytes 1049 */ 1050 size_t __ksize(const void *object) 1051 { 1052 struct folio *folio; 1053 1054 if (unlikely(object == ZERO_SIZE_PTR)) 1055 return 0; 1056 1057 folio = virt_to_folio(object); 1058 1059 if (unlikely(!folio_test_slab(folio))) { 1060 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) 1061 return 0; 1062 if (WARN_ON(object != folio_address(folio))) 1063 return 0; 1064 return folio_size(folio); 1065 } 1066 1067 #ifdef CONFIG_SLUB_DEBUG 1068 skip_orig_size_check(folio_slab(folio)->slab_cache, object); 1069 #endif 1070 1071 return slab_ksize(folio_slab(folio)->slab_cache); 1072 } 1073 1074 void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) 1075 { 1076 void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE, 1077 size, _RET_IP_); 1078 1079 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE); 1080 1081 ret = kasan_kmalloc(s, ret, size, gfpflags); 1082 return ret; 1083 } 1084 EXPORT_SYMBOL(kmalloc_trace); 1085 1086 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, 1087 int node, size_t size) 1088 { 1089 void *ret = __kmem_cache_alloc_node(s, gfpflags, node, size, _RET_IP_); 1090 1091 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node); 1092 1093 ret = kasan_kmalloc(s, ret, size, gfpflags); 1094 return ret; 1095 } 1096 EXPORT_SYMBOL(kmalloc_node_trace); 1097 1098 gfp_t kmalloc_fix_flags(gfp_t flags) 1099 { 1100 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 1101 1102 flags &= ~GFP_SLAB_BUG_MASK; 1103 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 1104 invalid_mask, &invalid_mask, flags, &flags); 1105 dump_stack(); 1106 1107 return flags; 1108 } 1109 1110 /* 1111 * To avoid unnecessary overhead, we pass through large allocation requests 1112 * directly to the page allocator. We use __GFP_COMP, because we will need to 1113 * know the allocation order to free the pages properly in kfree. 1114 */ 1115 1116 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node) 1117 { 1118 struct page *page; 1119 void *ptr = NULL; 1120 unsigned int order = get_order(size); 1121 1122 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 1123 flags = kmalloc_fix_flags(flags); 1124 1125 flags |= __GFP_COMP; 1126 page = alloc_pages_node(node, flags, order); 1127 if (page) { 1128 ptr = page_address(page); 1129 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 1130 PAGE_SIZE << order); 1131 } 1132 1133 ptr = kasan_kmalloc_large(ptr, size, flags); 1134 /* As ptr might get tagged, call kmemleak hook after KASAN. */ 1135 kmemleak_alloc(ptr, size, 1, flags); 1136 kmsan_kmalloc_large(ptr, size, flags); 1137 1138 return ptr; 1139 } 1140 1141 void *kmalloc_large(size_t size, gfp_t flags) 1142 { 1143 void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE); 1144 1145 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1146 flags, NUMA_NO_NODE); 1147 return ret; 1148 } 1149 EXPORT_SYMBOL(kmalloc_large); 1150 1151 void *kmalloc_large_node(size_t size, gfp_t flags, int node) 1152 { 1153 void *ret = __kmalloc_large_node(size, flags, node); 1154 1155 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1156 flags, node); 1157 return ret; 1158 } 1159 EXPORT_SYMBOL(kmalloc_large_node); 1160 1161 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1162 /* Randomize a generic freelist */ 1163 static void freelist_randomize(unsigned int *list, 1164 unsigned int count) 1165 { 1166 unsigned int rand; 1167 unsigned int i; 1168 1169 for (i = 0; i < count; i++) 1170 list[i] = i; 1171 1172 /* Fisher-Yates shuffle */ 1173 for (i = count - 1; i > 0; i--) { 1174 rand = get_random_u32_below(i + 1); 1175 swap(list[i], list[rand]); 1176 } 1177 } 1178 1179 /* Create a random sequence per cache */ 1180 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1181 gfp_t gfp) 1182 { 1183 1184 if (count < 2 || cachep->random_seq) 1185 return 0; 1186 1187 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1188 if (!cachep->random_seq) 1189 return -ENOMEM; 1190 1191 freelist_randomize(cachep->random_seq, count); 1192 return 0; 1193 } 1194 1195 /* Destroy the per-cache random freelist sequence */ 1196 void cache_random_seq_destroy(struct kmem_cache *cachep) 1197 { 1198 kfree(cachep->random_seq); 1199 cachep->random_seq = NULL; 1200 } 1201 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1202 1203 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 1204 #ifdef CONFIG_SLAB 1205 #define SLABINFO_RIGHTS (0600) 1206 #else 1207 #define SLABINFO_RIGHTS (0400) 1208 #endif 1209 1210 static void print_slabinfo_header(struct seq_file *m) 1211 { 1212 /* 1213 * Output format version, so at least we can change it 1214 * without _too_ many complaints. 1215 */ 1216 #ifdef CONFIG_DEBUG_SLAB 1217 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1218 #else 1219 seq_puts(m, "slabinfo - version: 2.1\n"); 1220 #endif 1221 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1222 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1223 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1224 #ifdef CONFIG_DEBUG_SLAB 1225 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1226 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1227 #endif 1228 seq_putc(m, '\n'); 1229 } 1230 1231 static void *slab_start(struct seq_file *m, loff_t *pos) 1232 { 1233 mutex_lock(&slab_mutex); 1234 return seq_list_start(&slab_caches, *pos); 1235 } 1236 1237 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1238 { 1239 return seq_list_next(p, &slab_caches, pos); 1240 } 1241 1242 static void slab_stop(struct seq_file *m, void *p) 1243 { 1244 mutex_unlock(&slab_mutex); 1245 } 1246 1247 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1248 { 1249 struct slabinfo sinfo; 1250 1251 memset(&sinfo, 0, sizeof(sinfo)); 1252 get_slabinfo(s, &sinfo); 1253 1254 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1255 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1256 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1257 1258 seq_printf(m, " : tunables %4u %4u %4u", 1259 sinfo.limit, sinfo.batchcount, sinfo.shared); 1260 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1261 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1262 slabinfo_show_stats(m, s); 1263 seq_putc(m, '\n'); 1264 } 1265 1266 static int slab_show(struct seq_file *m, void *p) 1267 { 1268 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1269 1270 if (p == slab_caches.next) 1271 print_slabinfo_header(m); 1272 cache_show(s, m); 1273 return 0; 1274 } 1275 1276 void dump_unreclaimable_slab(void) 1277 { 1278 struct kmem_cache *s; 1279 struct slabinfo sinfo; 1280 1281 /* 1282 * Here acquiring slab_mutex is risky since we don't prefer to get 1283 * sleep in oom path. But, without mutex hold, it may introduce a 1284 * risk of crash. 1285 * Use mutex_trylock to protect the list traverse, dump nothing 1286 * without acquiring the mutex. 1287 */ 1288 if (!mutex_trylock(&slab_mutex)) { 1289 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1290 return; 1291 } 1292 1293 pr_info("Unreclaimable slab info:\n"); 1294 pr_info("Name Used Total\n"); 1295 1296 list_for_each_entry(s, &slab_caches, list) { 1297 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1298 continue; 1299 1300 get_slabinfo(s, &sinfo); 1301 1302 if (sinfo.num_objs > 0) 1303 pr_info("%-17s %10luKB %10luKB\n", s->name, 1304 (sinfo.active_objs * s->size) / 1024, 1305 (sinfo.num_objs * s->size) / 1024); 1306 } 1307 mutex_unlock(&slab_mutex); 1308 } 1309 1310 /* 1311 * slabinfo_op - iterator that generates /proc/slabinfo 1312 * 1313 * Output layout: 1314 * cache-name 1315 * num-active-objs 1316 * total-objs 1317 * object size 1318 * num-active-slabs 1319 * total-slabs 1320 * num-pages-per-slab 1321 * + further values on SMP and with statistics enabled 1322 */ 1323 static const struct seq_operations slabinfo_op = { 1324 .start = slab_start, 1325 .next = slab_next, 1326 .stop = slab_stop, 1327 .show = slab_show, 1328 }; 1329 1330 static int slabinfo_open(struct inode *inode, struct file *file) 1331 { 1332 return seq_open(file, &slabinfo_op); 1333 } 1334 1335 static const struct proc_ops slabinfo_proc_ops = { 1336 .proc_flags = PROC_ENTRY_PERMANENT, 1337 .proc_open = slabinfo_open, 1338 .proc_read = seq_read, 1339 .proc_write = slabinfo_write, 1340 .proc_lseek = seq_lseek, 1341 .proc_release = seq_release, 1342 }; 1343 1344 static int __init slab_proc_init(void) 1345 { 1346 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1347 return 0; 1348 } 1349 module_init(slab_proc_init); 1350 1351 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1352 1353 static __always_inline __realloc_size(2) void * 1354 __do_krealloc(const void *p, size_t new_size, gfp_t flags) 1355 { 1356 void *ret; 1357 size_t ks; 1358 1359 /* Check for double-free before calling ksize. */ 1360 if (likely(!ZERO_OR_NULL_PTR(p))) { 1361 if (!kasan_check_byte(p)) 1362 return NULL; 1363 ks = ksize(p); 1364 } else 1365 ks = 0; 1366 1367 /* If the object still fits, repoison it precisely. */ 1368 if (ks >= new_size) { 1369 p = kasan_krealloc((void *)p, new_size, flags); 1370 return (void *)p; 1371 } 1372 1373 ret = kmalloc_track_caller(new_size, flags); 1374 if (ret && p) { 1375 /* Disable KASAN checks as the object's redzone is accessed. */ 1376 kasan_disable_current(); 1377 memcpy(ret, kasan_reset_tag(p), ks); 1378 kasan_enable_current(); 1379 } 1380 1381 return ret; 1382 } 1383 1384 /** 1385 * krealloc - reallocate memory. The contents will remain unchanged. 1386 * @p: object to reallocate memory for. 1387 * @new_size: how many bytes of memory are required. 1388 * @flags: the type of memory to allocate. 1389 * 1390 * The contents of the object pointed to are preserved up to the 1391 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1392 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1393 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1394 * 1395 * Return: pointer to the allocated memory or %NULL in case of error 1396 */ 1397 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1398 { 1399 void *ret; 1400 1401 if (unlikely(!new_size)) { 1402 kfree(p); 1403 return ZERO_SIZE_PTR; 1404 } 1405 1406 ret = __do_krealloc(p, new_size, flags); 1407 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1408 kfree(p); 1409 1410 return ret; 1411 } 1412 EXPORT_SYMBOL(krealloc); 1413 1414 /** 1415 * kfree_sensitive - Clear sensitive information in memory before freeing 1416 * @p: object to free memory of 1417 * 1418 * The memory of the object @p points to is zeroed before freed. 1419 * If @p is %NULL, kfree_sensitive() does nothing. 1420 * 1421 * Note: this function zeroes the whole allocated buffer which can be a good 1422 * deal bigger than the requested buffer size passed to kmalloc(). So be 1423 * careful when using this function in performance sensitive code. 1424 */ 1425 void kfree_sensitive(const void *p) 1426 { 1427 size_t ks; 1428 void *mem = (void *)p; 1429 1430 ks = ksize(mem); 1431 if (ks) { 1432 kasan_unpoison_range(mem, ks); 1433 memzero_explicit(mem, ks); 1434 } 1435 kfree(mem); 1436 } 1437 EXPORT_SYMBOL(kfree_sensitive); 1438 1439 size_t ksize(const void *objp) 1440 { 1441 /* 1442 * We need to first check that the pointer to the object is valid. 1443 * The KASAN report printed from ksize() is more useful, then when 1444 * it's printed later when the behaviour could be undefined due to 1445 * a potential use-after-free or double-free. 1446 * 1447 * We use kasan_check_byte(), which is supported for the hardware 1448 * tag-based KASAN mode, unlike kasan_check_read/write(). 1449 * 1450 * If the pointed to memory is invalid, we return 0 to avoid users of 1451 * ksize() writing to and potentially corrupting the memory region. 1452 * 1453 * We want to perform the check before __ksize(), to avoid potentially 1454 * crashing in __ksize() due to accessing invalid metadata. 1455 */ 1456 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1457 return 0; 1458 1459 return kfence_ksize(objp) ?: __ksize(objp); 1460 } 1461 EXPORT_SYMBOL(ksize); 1462 1463 /* Tracepoints definitions. */ 1464 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1465 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1466 EXPORT_TRACEPOINT_SYMBOL(kfree); 1467 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1468 1469 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1470 { 1471 if (__should_failslab(s, gfpflags)) 1472 return -ENOMEM; 1473 return 0; 1474 } 1475 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1476