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 | 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 out: 242 if (err) 243 return ERR_PTR(err); 244 return s; 245 246 out_free_cache: 247 kmem_cache_free(kmem_cache, s); 248 goto out; 249 } 250 251 /** 252 * kmem_cache_create_usercopy - Create a cache with a region suitable 253 * for copying to userspace 254 * @name: A string which is used in /proc/slabinfo to identify this cache. 255 * @size: The size of objects to be created in this cache. 256 * @align: The required alignment for the objects. 257 * @flags: SLAB flags 258 * @useroffset: Usercopy region offset 259 * @usersize: Usercopy region size 260 * @ctor: A constructor for the objects. 261 * 262 * Cannot be called within a interrupt, but can be interrupted. 263 * The @ctor is run when new pages are allocated by the cache. 264 * 265 * The flags are 266 * 267 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 268 * to catch references to uninitialised memory. 269 * 270 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 271 * for buffer overruns. 272 * 273 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 274 * cacheline. This can be beneficial if you're counting cycles as closely 275 * as davem. 276 * 277 * Return: a pointer to the cache on success, NULL on failure. 278 */ 279 struct kmem_cache * 280 kmem_cache_create_usercopy(const char *name, 281 unsigned int size, unsigned int align, 282 slab_flags_t flags, 283 unsigned int useroffset, unsigned int usersize, 284 void (*ctor)(void *)) 285 { 286 struct kmem_cache *s = NULL; 287 const char *cache_name; 288 int err; 289 290 #ifdef CONFIG_SLUB_DEBUG 291 /* 292 * If no slub_debug was enabled globally, the static key is not yet 293 * enabled by setup_slub_debug(). Enable it if the cache is being 294 * created with any of the debugging flags passed explicitly. 295 * It's also possible that this is the first cache created with 296 * SLAB_STORE_USER and we should init stack_depot for it. 297 */ 298 if (flags & SLAB_DEBUG_FLAGS) 299 static_branch_enable(&slub_debug_enabled); 300 if (flags & SLAB_STORE_USER) 301 stack_depot_init(); 302 #endif 303 304 mutex_lock(&slab_mutex); 305 306 err = kmem_cache_sanity_check(name, size); 307 if (err) { 308 goto out_unlock; 309 } 310 311 /* Refuse requests with allocator specific flags */ 312 if (flags & ~SLAB_FLAGS_PERMITTED) { 313 err = -EINVAL; 314 goto out_unlock; 315 } 316 317 /* 318 * Some allocators will constraint the set of valid flags to a subset 319 * of all flags. We expect them to define CACHE_CREATE_MASK in this 320 * case, and we'll just provide them with a sanitized version of the 321 * passed flags. 322 */ 323 flags &= CACHE_CREATE_MASK; 324 325 /* Fail closed on bad usersize of useroffset values. */ 326 if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || 327 WARN_ON(!usersize && useroffset) || 328 WARN_ON(size < usersize || size - usersize < useroffset)) 329 usersize = useroffset = 0; 330 331 if (!usersize) 332 s = __kmem_cache_alias(name, size, align, flags, ctor); 333 if (s) 334 goto out_unlock; 335 336 cache_name = kstrdup_const(name, GFP_KERNEL); 337 if (!cache_name) { 338 err = -ENOMEM; 339 goto out_unlock; 340 } 341 342 s = create_cache(cache_name, size, 343 calculate_alignment(flags, align, size), 344 flags, useroffset, usersize, ctor, NULL); 345 if (IS_ERR(s)) { 346 err = PTR_ERR(s); 347 kfree_const(cache_name); 348 } 349 350 out_unlock: 351 mutex_unlock(&slab_mutex); 352 353 if (err) { 354 if (flags & SLAB_PANIC) 355 panic("%s: Failed to create slab '%s'. Error %d\n", 356 __func__, name, err); 357 else { 358 pr_warn("%s(%s) failed with error %d\n", 359 __func__, name, err); 360 dump_stack(); 361 } 362 return NULL; 363 } 364 return s; 365 } 366 EXPORT_SYMBOL(kmem_cache_create_usercopy); 367 368 /** 369 * kmem_cache_create - Create a cache. 370 * @name: A string which is used in /proc/slabinfo to identify this cache. 371 * @size: The size of objects to be created in this cache. 372 * @align: The required alignment for the objects. 373 * @flags: SLAB flags 374 * @ctor: A constructor for the objects. 375 * 376 * Cannot be called within a interrupt, but can be interrupted. 377 * The @ctor is run when new pages are allocated by the cache. 378 * 379 * The flags are 380 * 381 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 382 * to catch references to uninitialised memory. 383 * 384 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 385 * for buffer overruns. 386 * 387 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 388 * cacheline. This can be beneficial if you're counting cycles as closely 389 * as davem. 390 * 391 * Return: a pointer to the cache on success, NULL on failure. 392 */ 393 struct kmem_cache * 394 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 395 slab_flags_t flags, void (*ctor)(void *)) 396 { 397 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 398 ctor); 399 } 400 EXPORT_SYMBOL(kmem_cache_create); 401 402 #ifdef SLAB_SUPPORTS_SYSFS 403 /* 404 * For a given kmem_cache, kmem_cache_destroy() should only be called 405 * once or there will be a use-after-free problem. The actual deletion 406 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock 407 * protection. So they are now done without holding those locks. 408 * 409 * Note that there will be a slight delay in the deletion of sysfs files 410 * if kmem_cache_release() is called indrectly from a work function. 411 */ 412 static void kmem_cache_release(struct kmem_cache *s) 413 { 414 sysfs_slab_unlink(s); 415 sysfs_slab_release(s); 416 } 417 #else 418 static void kmem_cache_release(struct kmem_cache *s) 419 { 420 slab_kmem_cache_release(s); 421 } 422 #endif 423 424 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 425 { 426 LIST_HEAD(to_destroy); 427 struct kmem_cache *s, *s2; 428 429 /* 430 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 431 * @slab_caches_to_rcu_destroy list. The slab pages are freed 432 * through RCU and the associated kmem_cache are dereferenced 433 * while freeing the pages, so the kmem_caches should be freed only 434 * after the pending RCU operations are finished. As rcu_barrier() 435 * is a pretty slow operation, we batch all pending destructions 436 * asynchronously. 437 */ 438 mutex_lock(&slab_mutex); 439 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 440 mutex_unlock(&slab_mutex); 441 442 if (list_empty(&to_destroy)) 443 return; 444 445 rcu_barrier(); 446 447 list_for_each_entry_safe(s, s2, &to_destroy, list) { 448 debugfs_slab_release(s); 449 kfence_shutdown_cache(s); 450 kmem_cache_release(s); 451 } 452 } 453 454 static int shutdown_cache(struct kmem_cache *s) 455 { 456 /* free asan quarantined objects */ 457 kasan_cache_shutdown(s); 458 459 if (__kmem_cache_shutdown(s) != 0) 460 return -EBUSY; 461 462 list_del(&s->list); 463 464 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 465 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 466 schedule_work(&slab_caches_to_rcu_destroy_work); 467 } else { 468 kfence_shutdown_cache(s); 469 debugfs_slab_release(s); 470 } 471 472 return 0; 473 } 474 475 void slab_kmem_cache_release(struct kmem_cache *s) 476 { 477 __kmem_cache_release(s); 478 kfree_const(s->name); 479 kmem_cache_free(kmem_cache, s); 480 } 481 482 void kmem_cache_destroy(struct kmem_cache *s) 483 { 484 int refcnt; 485 bool rcu_set; 486 487 if (unlikely(!s) || !kasan_check_byte(s)) 488 return; 489 490 cpus_read_lock(); 491 mutex_lock(&slab_mutex); 492 493 rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; 494 495 refcnt = --s->refcount; 496 if (refcnt) 497 goto out_unlock; 498 499 WARN(shutdown_cache(s), 500 "%s %s: Slab cache still has objects when called from %pS", 501 __func__, s->name, (void *)_RET_IP_); 502 out_unlock: 503 mutex_unlock(&slab_mutex); 504 cpus_read_unlock(); 505 if (!refcnt && !rcu_set) 506 kmem_cache_release(s); 507 } 508 EXPORT_SYMBOL(kmem_cache_destroy); 509 510 /** 511 * kmem_cache_shrink - Shrink a cache. 512 * @cachep: The cache to shrink. 513 * 514 * Releases as many slabs as possible for a cache. 515 * To help debugging, a zero exit status indicates all slabs were released. 516 * 517 * Return: %0 if all slabs were released, non-zero otherwise 518 */ 519 int kmem_cache_shrink(struct kmem_cache *cachep) 520 { 521 kasan_cache_shrink(cachep); 522 523 return __kmem_cache_shrink(cachep); 524 } 525 EXPORT_SYMBOL(kmem_cache_shrink); 526 527 bool slab_is_available(void) 528 { 529 return slab_state >= UP; 530 } 531 532 #ifdef CONFIG_PRINTK 533 /** 534 * kmem_valid_obj - does the pointer reference a valid slab object? 535 * @object: pointer to query. 536 * 537 * Return: %true if the pointer is to a not-yet-freed object from 538 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 539 * is to an already-freed object, and %false otherwise. 540 */ 541 bool kmem_valid_obj(void *object) 542 { 543 struct folio *folio; 544 545 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 546 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 547 return false; 548 folio = virt_to_folio(object); 549 return folio_test_slab(folio); 550 } 551 EXPORT_SYMBOL_GPL(kmem_valid_obj); 552 553 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 554 { 555 if (__kfence_obj_info(kpp, object, slab)) 556 return; 557 __kmem_obj_info(kpp, object, slab); 558 } 559 560 /** 561 * kmem_dump_obj - Print available slab provenance information 562 * @object: slab object for which to find provenance information. 563 * 564 * This function uses pr_cont(), so that the caller is expected to have 565 * printed out whatever preamble is appropriate. The provenance information 566 * depends on the type of object and on how much debugging is enabled. 567 * For a slab-cache object, the fact that it is a slab object is printed, 568 * and, if available, the slab name, return address, and stack trace from 569 * the allocation and last free path of that object. 570 * 571 * This function will splat if passed a pointer to a non-slab object. 572 * If you are not sure what type of object you have, you should instead 573 * use mem_dump_obj(). 574 */ 575 void kmem_dump_obj(void *object) 576 { 577 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 578 int i; 579 struct slab *slab; 580 unsigned long ptroffset; 581 struct kmem_obj_info kp = { }; 582 583 if (WARN_ON_ONCE(!virt_addr_valid(object))) 584 return; 585 slab = virt_to_slab(object); 586 if (WARN_ON_ONCE(!slab)) { 587 pr_cont(" non-slab memory.\n"); 588 return; 589 } 590 kmem_obj_info(&kp, object, slab); 591 if (kp.kp_slab_cache) 592 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 593 else 594 pr_cont(" slab%s", cp); 595 if (is_kfence_address(object)) 596 pr_cont(" (kfence)"); 597 if (kp.kp_objp) 598 pr_cont(" start %px", kp.kp_objp); 599 if (kp.kp_data_offset) 600 pr_cont(" data offset %lu", kp.kp_data_offset); 601 if (kp.kp_objp) { 602 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 603 pr_cont(" pointer offset %lu", ptroffset); 604 } 605 if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) 606 pr_cont(" size %u", kp.kp_slab_cache->object_size); 607 if (kp.kp_ret) 608 pr_cont(" allocated at %pS\n", kp.kp_ret); 609 else 610 pr_cont("\n"); 611 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 612 if (!kp.kp_stack[i]) 613 break; 614 pr_info(" %pS\n", kp.kp_stack[i]); 615 } 616 617 if (kp.kp_free_stack[0]) 618 pr_cont(" Free path:\n"); 619 620 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 621 if (!kp.kp_free_stack[i]) 622 break; 623 pr_info(" %pS\n", kp.kp_free_stack[i]); 624 } 625 626 } 627 EXPORT_SYMBOL_GPL(kmem_dump_obj); 628 #endif 629 630 /* Create a cache during boot when no slab services are available yet */ 631 void __init create_boot_cache(struct kmem_cache *s, const char *name, 632 unsigned int size, slab_flags_t flags, 633 unsigned int useroffset, unsigned int usersize) 634 { 635 int err; 636 unsigned int align = ARCH_KMALLOC_MINALIGN; 637 638 s->name = name; 639 s->size = s->object_size = size; 640 641 /* 642 * For power of two sizes, guarantee natural alignment for kmalloc 643 * caches, regardless of SL*B debugging options. 644 */ 645 if (is_power_of_2(size)) 646 align = max(align, size); 647 s->align = calculate_alignment(flags, align, size); 648 649 #ifdef CONFIG_HARDENED_USERCOPY 650 s->useroffset = useroffset; 651 s->usersize = usersize; 652 #endif 653 654 err = __kmem_cache_create(s, flags); 655 656 if (err) 657 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 658 name, size, err); 659 660 s->refcount = -1; /* Exempt from merging for now */ 661 } 662 663 static struct kmem_cache *__init create_kmalloc_cache(const char *name, 664 unsigned int size, 665 slab_flags_t flags) 666 { 667 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 668 669 if (!s) 670 panic("Out of memory when creating slab %s\n", name); 671 672 create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size); 673 list_add(&s->list, &slab_caches); 674 s->refcount = 1; 675 return s; 676 } 677 678 struct kmem_cache * 679 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 680 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 681 EXPORT_SYMBOL(kmalloc_caches); 682 683 /* 684 * Conversion table for small slabs sizes / 8 to the index in the 685 * kmalloc array. This is necessary for slabs < 192 since we have non power 686 * of two cache sizes there. The size of larger slabs can be determined using 687 * fls. 688 */ 689 static u8 size_index[24] __ro_after_init = { 690 3, /* 8 */ 691 4, /* 16 */ 692 5, /* 24 */ 693 5, /* 32 */ 694 6, /* 40 */ 695 6, /* 48 */ 696 6, /* 56 */ 697 6, /* 64 */ 698 1, /* 72 */ 699 1, /* 80 */ 700 1, /* 88 */ 701 1, /* 96 */ 702 7, /* 104 */ 703 7, /* 112 */ 704 7, /* 120 */ 705 7, /* 128 */ 706 2, /* 136 */ 707 2, /* 144 */ 708 2, /* 152 */ 709 2, /* 160 */ 710 2, /* 168 */ 711 2, /* 176 */ 712 2, /* 184 */ 713 2 /* 192 */ 714 }; 715 716 static inline unsigned int size_index_elem(unsigned int bytes) 717 { 718 return (bytes - 1) / 8; 719 } 720 721 /* 722 * Find the kmem_cache structure that serves a given size of 723 * allocation 724 */ 725 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 726 { 727 unsigned int index; 728 729 if (size <= 192) { 730 if (!size) 731 return ZERO_SIZE_PTR; 732 733 index = size_index[size_index_elem(size)]; 734 } else { 735 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 736 return NULL; 737 index = fls(size - 1); 738 } 739 740 return kmalloc_caches[kmalloc_type(flags)][index]; 741 } 742 743 size_t kmalloc_size_roundup(size_t size) 744 { 745 struct kmem_cache *c; 746 747 /* Short-circuit the 0 size case. */ 748 if (unlikely(size == 0)) 749 return 0; 750 /* Short-circuit saturated "too-large" case. */ 751 if (unlikely(size == SIZE_MAX)) 752 return SIZE_MAX; 753 /* Above the smaller buckets, size is a multiple of page size. */ 754 if (size > KMALLOC_MAX_CACHE_SIZE) 755 return PAGE_SIZE << get_order(size); 756 757 /* The flags don't matter since size_index is common to all. */ 758 c = kmalloc_slab(size, GFP_KERNEL); 759 return c ? c->object_size : 0; 760 } 761 EXPORT_SYMBOL(kmalloc_size_roundup); 762 763 #ifdef CONFIG_ZONE_DMA 764 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 765 #else 766 #define KMALLOC_DMA_NAME(sz) 767 #endif 768 769 #ifdef CONFIG_MEMCG_KMEM 770 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 771 #else 772 #define KMALLOC_CGROUP_NAME(sz) 773 #endif 774 775 #ifndef CONFIG_SLUB_TINY 776 #define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz, 777 #else 778 #define KMALLOC_RCL_NAME(sz) 779 #endif 780 781 #define INIT_KMALLOC_INFO(__size, __short_size) \ 782 { \ 783 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 784 KMALLOC_RCL_NAME(__short_size) \ 785 KMALLOC_CGROUP_NAME(__short_size) \ 786 KMALLOC_DMA_NAME(__short_size) \ 787 .size = __size, \ 788 } 789 790 /* 791 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 792 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is 793 * kmalloc-2M. 794 */ 795 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 796 INIT_KMALLOC_INFO(0, 0), 797 INIT_KMALLOC_INFO(96, 96), 798 INIT_KMALLOC_INFO(192, 192), 799 INIT_KMALLOC_INFO(8, 8), 800 INIT_KMALLOC_INFO(16, 16), 801 INIT_KMALLOC_INFO(32, 32), 802 INIT_KMALLOC_INFO(64, 64), 803 INIT_KMALLOC_INFO(128, 128), 804 INIT_KMALLOC_INFO(256, 256), 805 INIT_KMALLOC_INFO(512, 512), 806 INIT_KMALLOC_INFO(1024, 1k), 807 INIT_KMALLOC_INFO(2048, 2k), 808 INIT_KMALLOC_INFO(4096, 4k), 809 INIT_KMALLOC_INFO(8192, 8k), 810 INIT_KMALLOC_INFO(16384, 16k), 811 INIT_KMALLOC_INFO(32768, 32k), 812 INIT_KMALLOC_INFO(65536, 64k), 813 INIT_KMALLOC_INFO(131072, 128k), 814 INIT_KMALLOC_INFO(262144, 256k), 815 INIT_KMALLOC_INFO(524288, 512k), 816 INIT_KMALLOC_INFO(1048576, 1M), 817 INIT_KMALLOC_INFO(2097152, 2M) 818 }; 819 820 /* 821 * Patch up the size_index table if we have strange large alignment 822 * requirements for the kmalloc array. This is only the case for 823 * MIPS it seems. The standard arches will not generate any code here. 824 * 825 * Largest permitted alignment is 256 bytes due to the way we 826 * handle the index determination for the smaller caches. 827 * 828 * Make sure that nothing crazy happens if someone starts tinkering 829 * around with ARCH_KMALLOC_MINALIGN 830 */ 831 void __init setup_kmalloc_cache_index_table(void) 832 { 833 unsigned int i; 834 835 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 836 !is_power_of_2(KMALLOC_MIN_SIZE)); 837 838 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 839 unsigned int elem = size_index_elem(i); 840 841 if (elem >= ARRAY_SIZE(size_index)) 842 break; 843 size_index[elem] = KMALLOC_SHIFT_LOW; 844 } 845 846 if (KMALLOC_MIN_SIZE >= 64) { 847 /* 848 * The 96 byte sized cache is not used if the alignment 849 * is 64 byte. 850 */ 851 for (i = 64 + 8; i <= 96; i += 8) 852 size_index[size_index_elem(i)] = 7; 853 854 } 855 856 if (KMALLOC_MIN_SIZE >= 128) { 857 /* 858 * The 192 byte sized cache is not used if the alignment 859 * is 128 byte. Redirect kmalloc to use the 256 byte cache 860 * instead. 861 */ 862 for (i = 128 + 8; i <= 192; i += 8) 863 size_index[size_index_elem(i)] = 8; 864 } 865 } 866 867 static unsigned int __kmalloc_minalign(void) 868 { 869 #ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC 870 if (io_tlb_default_mem.nslabs) 871 return ARCH_KMALLOC_MINALIGN; 872 #endif 873 return dma_get_cache_alignment(); 874 } 875 876 void __init 877 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 878 { 879 unsigned int minalign = __kmalloc_minalign(); 880 unsigned int aligned_size = kmalloc_info[idx].size; 881 int aligned_idx = idx; 882 883 if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) { 884 flags |= SLAB_RECLAIM_ACCOUNT; 885 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 886 if (mem_cgroup_kmem_disabled()) { 887 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 888 return; 889 } 890 flags |= SLAB_ACCOUNT; 891 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 892 flags |= SLAB_CACHE_DMA; 893 } 894 895 if (minalign > ARCH_KMALLOC_MINALIGN) { 896 aligned_size = ALIGN(aligned_size, minalign); 897 aligned_idx = __kmalloc_index(aligned_size, false); 898 } 899 900 if (!kmalloc_caches[type][aligned_idx]) 901 kmalloc_caches[type][aligned_idx] = create_kmalloc_cache( 902 kmalloc_info[aligned_idx].name[type], 903 aligned_size, flags); 904 if (idx != aligned_idx) 905 kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx]; 906 907 /* 908 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 909 * KMALLOC_NORMAL caches. 910 */ 911 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 912 kmalloc_caches[type][idx]->refcount = -1; 913 } 914 915 /* 916 * Create the kmalloc array. Some of the regular kmalloc arrays 917 * may already have been created because they were needed to 918 * enable allocations for slab creation. 919 */ 920 void __init create_kmalloc_caches(slab_flags_t flags) 921 { 922 int i; 923 enum kmalloc_cache_type type; 924 925 /* 926 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 927 */ 928 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 929 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 930 if (!kmalloc_caches[type][i]) 931 new_kmalloc_cache(i, type, flags); 932 933 /* 934 * Caches that are not of the two-to-the-power-of size. 935 * These have to be created immediately after the 936 * earlier power of two caches 937 */ 938 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 939 !kmalloc_caches[type][1]) 940 new_kmalloc_cache(1, type, flags); 941 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 942 !kmalloc_caches[type][2]) 943 new_kmalloc_cache(2, type, flags); 944 } 945 } 946 947 /* Kmalloc array is now usable */ 948 slab_state = UP; 949 } 950 951 void free_large_kmalloc(struct folio *folio, void *object) 952 { 953 unsigned int order = folio_order(folio); 954 955 if (WARN_ON_ONCE(order == 0)) 956 pr_warn_once("object pointer: 0x%p\n", object); 957 958 kmemleak_free(object); 959 kasan_kfree_large(object); 960 kmsan_kfree_large(object); 961 962 mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B, 963 -(PAGE_SIZE << order)); 964 __free_pages(folio_page(folio, 0), order); 965 } 966 967 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node); 968 static __always_inline 969 void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) 970 { 971 struct kmem_cache *s; 972 void *ret; 973 974 if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { 975 ret = __kmalloc_large_node(size, flags, node); 976 trace_kmalloc(caller, ret, size, 977 PAGE_SIZE << get_order(size), flags, node); 978 return ret; 979 } 980 981 s = kmalloc_slab(size, flags); 982 983 if (unlikely(ZERO_OR_NULL_PTR(s))) 984 return s; 985 986 ret = __kmem_cache_alloc_node(s, flags, node, size, caller); 987 ret = kasan_kmalloc(s, ret, size, flags); 988 trace_kmalloc(caller, ret, size, s->size, flags, node); 989 return ret; 990 } 991 992 void *__kmalloc_node(size_t size, gfp_t flags, int node) 993 { 994 return __do_kmalloc_node(size, flags, node, _RET_IP_); 995 } 996 EXPORT_SYMBOL(__kmalloc_node); 997 998 void *__kmalloc(size_t size, gfp_t flags) 999 { 1000 return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_); 1001 } 1002 EXPORT_SYMBOL(__kmalloc); 1003 1004 void *__kmalloc_node_track_caller(size_t size, gfp_t flags, 1005 int node, unsigned long caller) 1006 { 1007 return __do_kmalloc_node(size, flags, node, caller); 1008 } 1009 EXPORT_SYMBOL(__kmalloc_node_track_caller); 1010 1011 /** 1012 * kfree - free previously allocated memory 1013 * @object: pointer returned by kmalloc() or kmem_cache_alloc() 1014 * 1015 * If @object is NULL, no operation is performed. 1016 */ 1017 void kfree(const void *object) 1018 { 1019 struct folio *folio; 1020 struct slab *slab; 1021 struct kmem_cache *s; 1022 1023 trace_kfree(_RET_IP_, object); 1024 1025 if (unlikely(ZERO_OR_NULL_PTR(object))) 1026 return; 1027 1028 folio = virt_to_folio(object); 1029 if (unlikely(!folio_test_slab(folio))) { 1030 free_large_kmalloc(folio, (void *)object); 1031 return; 1032 } 1033 1034 slab = folio_slab(folio); 1035 s = slab->slab_cache; 1036 __kmem_cache_free(s, (void *)object, _RET_IP_); 1037 } 1038 EXPORT_SYMBOL(kfree); 1039 1040 /** 1041 * __ksize -- Report full size of underlying allocation 1042 * @object: pointer to the object 1043 * 1044 * This should only be used internally to query the true size of allocations. 1045 * It is not meant to be a way to discover the usable size of an allocation 1046 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond 1047 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS, 1048 * and/or FORTIFY_SOURCE. 1049 * 1050 * Return: size of the actual memory used by @object in bytes 1051 */ 1052 size_t __ksize(const void *object) 1053 { 1054 struct folio *folio; 1055 1056 if (unlikely(object == ZERO_SIZE_PTR)) 1057 return 0; 1058 1059 folio = virt_to_folio(object); 1060 1061 if (unlikely(!folio_test_slab(folio))) { 1062 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) 1063 return 0; 1064 if (WARN_ON(object != folio_address(folio))) 1065 return 0; 1066 return folio_size(folio); 1067 } 1068 1069 #ifdef CONFIG_SLUB_DEBUG 1070 skip_orig_size_check(folio_slab(folio)->slab_cache, object); 1071 #endif 1072 1073 return slab_ksize(folio_slab(folio)->slab_cache); 1074 } 1075 1076 void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) 1077 { 1078 void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE, 1079 size, _RET_IP_); 1080 1081 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE); 1082 1083 ret = kasan_kmalloc(s, ret, size, gfpflags); 1084 return ret; 1085 } 1086 EXPORT_SYMBOL(kmalloc_trace); 1087 1088 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, 1089 int node, size_t size) 1090 { 1091 void *ret = __kmem_cache_alloc_node(s, gfpflags, node, size, _RET_IP_); 1092 1093 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node); 1094 1095 ret = kasan_kmalloc(s, ret, size, gfpflags); 1096 return ret; 1097 } 1098 EXPORT_SYMBOL(kmalloc_node_trace); 1099 1100 gfp_t kmalloc_fix_flags(gfp_t flags) 1101 { 1102 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 1103 1104 flags &= ~GFP_SLAB_BUG_MASK; 1105 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 1106 invalid_mask, &invalid_mask, flags, &flags); 1107 dump_stack(); 1108 1109 return flags; 1110 } 1111 1112 /* 1113 * To avoid unnecessary overhead, we pass through large allocation requests 1114 * directly to the page allocator. We use __GFP_COMP, because we will need to 1115 * know the allocation order to free the pages properly in kfree. 1116 */ 1117 1118 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node) 1119 { 1120 struct page *page; 1121 void *ptr = NULL; 1122 unsigned int order = get_order(size); 1123 1124 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 1125 flags = kmalloc_fix_flags(flags); 1126 1127 flags |= __GFP_COMP; 1128 page = alloc_pages_node(node, flags, order); 1129 if (page) { 1130 ptr = page_address(page); 1131 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 1132 PAGE_SIZE << order); 1133 } 1134 1135 ptr = kasan_kmalloc_large(ptr, size, flags); 1136 /* As ptr might get tagged, call kmemleak hook after KASAN. */ 1137 kmemleak_alloc(ptr, size, 1, flags); 1138 kmsan_kmalloc_large(ptr, size, flags); 1139 1140 return ptr; 1141 } 1142 1143 void *kmalloc_large(size_t size, gfp_t flags) 1144 { 1145 void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE); 1146 1147 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1148 flags, NUMA_NO_NODE); 1149 return ret; 1150 } 1151 EXPORT_SYMBOL(kmalloc_large); 1152 1153 void *kmalloc_large_node(size_t size, gfp_t flags, int node) 1154 { 1155 void *ret = __kmalloc_large_node(size, flags, node); 1156 1157 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1158 flags, node); 1159 return ret; 1160 } 1161 EXPORT_SYMBOL(kmalloc_large_node); 1162 1163 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1164 /* Randomize a generic freelist */ 1165 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 1166 unsigned int count) 1167 { 1168 unsigned int rand; 1169 unsigned int i; 1170 1171 for (i = 0; i < count; i++) 1172 list[i] = i; 1173 1174 /* Fisher-Yates shuffle */ 1175 for (i = count - 1; i > 0; i--) { 1176 rand = prandom_u32_state(state); 1177 rand %= (i + 1); 1178 swap(list[i], list[rand]); 1179 } 1180 } 1181 1182 /* Create a random sequence per cache */ 1183 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1184 gfp_t gfp) 1185 { 1186 struct rnd_state state; 1187 1188 if (count < 2 || cachep->random_seq) 1189 return 0; 1190 1191 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1192 if (!cachep->random_seq) 1193 return -ENOMEM; 1194 1195 /* Get best entropy at this stage of boot */ 1196 prandom_seed_state(&state, get_random_long()); 1197 1198 freelist_randomize(&state, cachep->random_seq, count); 1199 return 0; 1200 } 1201 1202 /* Destroy the per-cache random freelist sequence */ 1203 void cache_random_seq_destroy(struct kmem_cache *cachep) 1204 { 1205 kfree(cachep->random_seq); 1206 cachep->random_seq = NULL; 1207 } 1208 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1209 1210 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 1211 #ifdef CONFIG_SLAB 1212 #define SLABINFO_RIGHTS (0600) 1213 #else 1214 #define SLABINFO_RIGHTS (0400) 1215 #endif 1216 1217 static void print_slabinfo_header(struct seq_file *m) 1218 { 1219 /* 1220 * Output format version, so at least we can change it 1221 * without _too_ many complaints. 1222 */ 1223 #ifdef CONFIG_DEBUG_SLAB 1224 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1225 #else 1226 seq_puts(m, "slabinfo - version: 2.1\n"); 1227 #endif 1228 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1229 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1230 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1231 #ifdef CONFIG_DEBUG_SLAB 1232 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1233 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1234 #endif 1235 seq_putc(m, '\n'); 1236 } 1237 1238 static void *slab_start(struct seq_file *m, loff_t *pos) 1239 { 1240 mutex_lock(&slab_mutex); 1241 return seq_list_start(&slab_caches, *pos); 1242 } 1243 1244 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1245 { 1246 return seq_list_next(p, &slab_caches, pos); 1247 } 1248 1249 static void slab_stop(struct seq_file *m, void *p) 1250 { 1251 mutex_unlock(&slab_mutex); 1252 } 1253 1254 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1255 { 1256 struct slabinfo sinfo; 1257 1258 memset(&sinfo, 0, sizeof(sinfo)); 1259 get_slabinfo(s, &sinfo); 1260 1261 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1262 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1263 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1264 1265 seq_printf(m, " : tunables %4u %4u %4u", 1266 sinfo.limit, sinfo.batchcount, sinfo.shared); 1267 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1268 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1269 slabinfo_show_stats(m, s); 1270 seq_putc(m, '\n'); 1271 } 1272 1273 static int slab_show(struct seq_file *m, void *p) 1274 { 1275 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1276 1277 if (p == slab_caches.next) 1278 print_slabinfo_header(m); 1279 cache_show(s, m); 1280 return 0; 1281 } 1282 1283 void dump_unreclaimable_slab(void) 1284 { 1285 struct kmem_cache *s; 1286 struct slabinfo sinfo; 1287 1288 /* 1289 * Here acquiring slab_mutex is risky since we don't prefer to get 1290 * sleep in oom path. But, without mutex hold, it may introduce a 1291 * risk of crash. 1292 * Use mutex_trylock to protect the list traverse, dump nothing 1293 * without acquiring the mutex. 1294 */ 1295 if (!mutex_trylock(&slab_mutex)) { 1296 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1297 return; 1298 } 1299 1300 pr_info("Unreclaimable slab info:\n"); 1301 pr_info("Name Used Total\n"); 1302 1303 list_for_each_entry(s, &slab_caches, list) { 1304 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1305 continue; 1306 1307 get_slabinfo(s, &sinfo); 1308 1309 if (sinfo.num_objs > 0) 1310 pr_info("%-17s %10luKB %10luKB\n", s->name, 1311 (sinfo.active_objs * s->size) / 1024, 1312 (sinfo.num_objs * s->size) / 1024); 1313 } 1314 mutex_unlock(&slab_mutex); 1315 } 1316 1317 /* 1318 * slabinfo_op - iterator that generates /proc/slabinfo 1319 * 1320 * Output layout: 1321 * cache-name 1322 * num-active-objs 1323 * total-objs 1324 * object size 1325 * num-active-slabs 1326 * total-slabs 1327 * num-pages-per-slab 1328 * + further values on SMP and with statistics enabled 1329 */ 1330 static const struct seq_operations slabinfo_op = { 1331 .start = slab_start, 1332 .next = slab_next, 1333 .stop = slab_stop, 1334 .show = slab_show, 1335 }; 1336 1337 static int slabinfo_open(struct inode *inode, struct file *file) 1338 { 1339 return seq_open(file, &slabinfo_op); 1340 } 1341 1342 static const struct proc_ops slabinfo_proc_ops = { 1343 .proc_flags = PROC_ENTRY_PERMANENT, 1344 .proc_open = slabinfo_open, 1345 .proc_read = seq_read, 1346 .proc_write = slabinfo_write, 1347 .proc_lseek = seq_lseek, 1348 .proc_release = seq_release, 1349 }; 1350 1351 static int __init slab_proc_init(void) 1352 { 1353 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1354 return 0; 1355 } 1356 module_init(slab_proc_init); 1357 1358 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1359 1360 static __always_inline __realloc_size(2) void * 1361 __do_krealloc(const void *p, size_t new_size, gfp_t flags) 1362 { 1363 void *ret; 1364 size_t ks; 1365 1366 /* Check for double-free before calling ksize. */ 1367 if (likely(!ZERO_OR_NULL_PTR(p))) { 1368 if (!kasan_check_byte(p)) 1369 return NULL; 1370 ks = ksize(p); 1371 } else 1372 ks = 0; 1373 1374 /* If the object still fits, repoison it precisely. */ 1375 if (ks >= new_size) { 1376 p = kasan_krealloc((void *)p, new_size, flags); 1377 return (void *)p; 1378 } 1379 1380 ret = kmalloc_track_caller(new_size, flags); 1381 if (ret && p) { 1382 /* Disable KASAN checks as the object's redzone is accessed. */ 1383 kasan_disable_current(); 1384 memcpy(ret, kasan_reset_tag(p), ks); 1385 kasan_enable_current(); 1386 } 1387 1388 return ret; 1389 } 1390 1391 /** 1392 * krealloc - reallocate memory. The contents will remain unchanged. 1393 * @p: object to reallocate memory for. 1394 * @new_size: how many bytes of memory are required. 1395 * @flags: the type of memory to allocate. 1396 * 1397 * The contents of the object pointed to are preserved up to the 1398 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1399 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1400 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1401 * 1402 * Return: pointer to the allocated memory or %NULL in case of error 1403 */ 1404 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1405 { 1406 void *ret; 1407 1408 if (unlikely(!new_size)) { 1409 kfree(p); 1410 return ZERO_SIZE_PTR; 1411 } 1412 1413 ret = __do_krealloc(p, new_size, flags); 1414 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1415 kfree(p); 1416 1417 return ret; 1418 } 1419 EXPORT_SYMBOL(krealloc); 1420 1421 /** 1422 * kfree_sensitive - Clear sensitive information in memory before freeing 1423 * @p: object to free memory of 1424 * 1425 * The memory of the object @p points to is zeroed before freed. 1426 * If @p is %NULL, kfree_sensitive() does nothing. 1427 * 1428 * Note: this function zeroes the whole allocated buffer which can be a good 1429 * deal bigger than the requested buffer size passed to kmalloc(). So be 1430 * careful when using this function in performance sensitive code. 1431 */ 1432 void kfree_sensitive(const void *p) 1433 { 1434 size_t ks; 1435 void *mem = (void *)p; 1436 1437 ks = ksize(mem); 1438 if (ks) { 1439 kasan_unpoison_range(mem, ks); 1440 memzero_explicit(mem, ks); 1441 } 1442 kfree(mem); 1443 } 1444 EXPORT_SYMBOL(kfree_sensitive); 1445 1446 size_t ksize(const void *objp) 1447 { 1448 /* 1449 * We need to first check that the pointer to the object is valid. 1450 * The KASAN report printed from ksize() is more useful, then when 1451 * it's printed later when the behaviour could be undefined due to 1452 * a potential use-after-free or double-free. 1453 * 1454 * We use kasan_check_byte(), which is supported for the hardware 1455 * tag-based KASAN mode, unlike kasan_check_read/write(). 1456 * 1457 * If the pointed to memory is invalid, we return 0 to avoid users of 1458 * ksize() writing to and potentially corrupting the memory region. 1459 * 1460 * We want to perform the check before __ksize(), to avoid potentially 1461 * crashing in __ksize() due to accessing invalid metadata. 1462 */ 1463 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1464 return 0; 1465 1466 return kfence_ksize(objp) ?: __ksize(objp); 1467 } 1468 EXPORT_SYMBOL(ksize); 1469 1470 /* Tracepoints definitions. */ 1471 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1472 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1473 EXPORT_TRACEPOINT_SYMBOL(kfree); 1474 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1475 1476 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1477 { 1478 if (__should_failslab(s, gfpflags)) 1479 return -ENOMEM; 1480 return 0; 1481 } 1482 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1483