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 #ifdef CONFIG_HARDENED_USERCOPY 147 if (s->usersize) 148 return 1; 149 #endif 150 151 /* 152 * We may have set a slab to be unmergeable during bootstrap. 153 */ 154 if (s->refcount < 0) 155 return 1; 156 157 return 0; 158 } 159 160 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 161 slab_flags_t flags, const char *name, void (*ctor)(void *)) 162 { 163 struct kmem_cache *s; 164 165 if (slab_nomerge) 166 return NULL; 167 168 if (ctor) 169 return NULL; 170 171 size = ALIGN(size, sizeof(void *)); 172 align = calculate_alignment(flags, align, size); 173 size = ALIGN(size, align); 174 flags = kmem_cache_flags(size, flags, name); 175 176 if (flags & SLAB_NEVER_MERGE) 177 return NULL; 178 179 list_for_each_entry_reverse(s, &slab_caches, list) { 180 if (slab_unmergeable(s)) 181 continue; 182 183 if (size > s->size) 184 continue; 185 186 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 187 continue; 188 /* 189 * Check if alignment is compatible. 190 * Courtesy of Adrian Drzewiecki 191 */ 192 if ((s->size & ~(align - 1)) != s->size) 193 continue; 194 195 if (s->size - size >= sizeof(void *)) 196 continue; 197 198 if (IS_ENABLED(CONFIG_SLAB) && align && 199 (align > s->align || s->align % align)) 200 continue; 201 202 return s; 203 } 204 return NULL; 205 } 206 207 static struct kmem_cache *create_cache(const char *name, 208 unsigned int object_size, unsigned int align, 209 slab_flags_t flags, unsigned int useroffset, 210 unsigned int usersize, void (*ctor)(void *), 211 struct kmem_cache *root_cache) 212 { 213 struct kmem_cache *s; 214 int err; 215 216 if (WARN_ON(useroffset + usersize > object_size)) 217 useroffset = usersize = 0; 218 219 err = -ENOMEM; 220 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 221 if (!s) 222 goto out; 223 224 s->name = name; 225 s->size = s->object_size = object_size; 226 s->align = align; 227 s->ctor = ctor; 228 #ifdef CONFIG_HARDENED_USERCOPY 229 s->useroffset = useroffset; 230 s->usersize = usersize; 231 #endif 232 233 err = __kmem_cache_create(s, flags); 234 if (err) 235 goto out_free_cache; 236 237 s->refcount = 1; 238 list_add(&s->list, &slab_caches); 239 out: 240 if (err) 241 return ERR_PTR(err); 242 return s; 243 244 out_free_cache: 245 kmem_cache_free(kmem_cache, s); 246 goto out; 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 struct kmem_cache *__init create_kmalloc_cache(const char *name, 662 unsigned int size, slab_flags_t flags, 663 unsigned int useroffset, unsigned int usersize) 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, useroffset, 671 usersize); 672 list_add(&s->list, &slab_caches); 673 s->refcount = 1; 674 return s; 675 } 676 677 struct kmem_cache * 678 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 679 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 680 EXPORT_SYMBOL(kmalloc_caches); 681 682 /* 683 * Conversion table for small slabs sizes / 8 to the index in the 684 * kmalloc array. This is necessary for slabs < 192 since we have non power 685 * of two cache sizes there. The size of larger slabs can be determined using 686 * fls. 687 */ 688 static u8 size_index[24] __ro_after_init = { 689 3, /* 8 */ 690 4, /* 16 */ 691 5, /* 24 */ 692 5, /* 32 */ 693 6, /* 40 */ 694 6, /* 48 */ 695 6, /* 56 */ 696 6, /* 64 */ 697 1, /* 72 */ 698 1, /* 80 */ 699 1, /* 88 */ 700 1, /* 96 */ 701 7, /* 104 */ 702 7, /* 112 */ 703 7, /* 120 */ 704 7, /* 128 */ 705 2, /* 136 */ 706 2, /* 144 */ 707 2, /* 152 */ 708 2, /* 160 */ 709 2, /* 168 */ 710 2, /* 176 */ 711 2, /* 184 */ 712 2 /* 192 */ 713 }; 714 715 static inline unsigned int size_index_elem(unsigned int bytes) 716 { 717 return (bytes - 1) / 8; 718 } 719 720 /* 721 * Find the kmem_cache structure that serves a given size of 722 * allocation 723 */ 724 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 725 { 726 unsigned int index; 727 728 if (size <= 192) { 729 if (!size) 730 return ZERO_SIZE_PTR; 731 732 index = size_index[size_index_elem(size)]; 733 } else { 734 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 735 return NULL; 736 index = fls(size - 1); 737 } 738 739 return kmalloc_caches[kmalloc_type(flags)][index]; 740 } 741 742 size_t kmalloc_size_roundup(size_t size) 743 { 744 struct kmem_cache *c; 745 746 /* Short-circuit the 0 size case. */ 747 if (unlikely(size == 0)) 748 return 0; 749 /* Short-circuit saturated "too-large" case. */ 750 if (unlikely(size == SIZE_MAX)) 751 return SIZE_MAX; 752 /* Above the smaller buckets, size is a multiple of page size. */ 753 if (size > KMALLOC_MAX_CACHE_SIZE) 754 return PAGE_SIZE << get_order(size); 755 756 /* The flags don't matter since size_index is common to all. */ 757 c = kmalloc_slab(size, GFP_KERNEL); 758 return c ? c->object_size : 0; 759 } 760 EXPORT_SYMBOL(kmalloc_size_roundup); 761 762 #ifdef CONFIG_ZONE_DMA 763 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 764 #else 765 #define KMALLOC_DMA_NAME(sz) 766 #endif 767 768 #ifdef CONFIG_MEMCG_KMEM 769 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 770 #else 771 #define KMALLOC_CGROUP_NAME(sz) 772 #endif 773 774 #ifndef CONFIG_SLUB_TINY 775 #define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz, 776 #else 777 #define KMALLOC_RCL_NAME(sz) 778 #endif 779 780 #define INIT_KMALLOC_INFO(__size, __short_size) \ 781 { \ 782 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 783 KMALLOC_RCL_NAME(__short_size) \ 784 KMALLOC_CGROUP_NAME(__short_size) \ 785 KMALLOC_DMA_NAME(__short_size) \ 786 .size = __size, \ 787 } 788 789 /* 790 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 791 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is 792 * kmalloc-2M. 793 */ 794 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 795 INIT_KMALLOC_INFO(0, 0), 796 INIT_KMALLOC_INFO(96, 96), 797 INIT_KMALLOC_INFO(192, 192), 798 INIT_KMALLOC_INFO(8, 8), 799 INIT_KMALLOC_INFO(16, 16), 800 INIT_KMALLOC_INFO(32, 32), 801 INIT_KMALLOC_INFO(64, 64), 802 INIT_KMALLOC_INFO(128, 128), 803 INIT_KMALLOC_INFO(256, 256), 804 INIT_KMALLOC_INFO(512, 512), 805 INIT_KMALLOC_INFO(1024, 1k), 806 INIT_KMALLOC_INFO(2048, 2k), 807 INIT_KMALLOC_INFO(4096, 4k), 808 INIT_KMALLOC_INFO(8192, 8k), 809 INIT_KMALLOC_INFO(16384, 16k), 810 INIT_KMALLOC_INFO(32768, 32k), 811 INIT_KMALLOC_INFO(65536, 64k), 812 INIT_KMALLOC_INFO(131072, 128k), 813 INIT_KMALLOC_INFO(262144, 256k), 814 INIT_KMALLOC_INFO(524288, 512k), 815 INIT_KMALLOC_INFO(1048576, 1M), 816 INIT_KMALLOC_INFO(2097152, 2M) 817 }; 818 819 /* 820 * Patch up the size_index table if we have strange large alignment 821 * requirements for the kmalloc array. This is only the case for 822 * MIPS it seems. The standard arches will not generate any code here. 823 * 824 * Largest permitted alignment is 256 bytes due to the way we 825 * handle the index determination for the smaller caches. 826 * 827 * Make sure that nothing crazy happens if someone starts tinkering 828 * around with ARCH_KMALLOC_MINALIGN 829 */ 830 void __init setup_kmalloc_cache_index_table(void) 831 { 832 unsigned int i; 833 834 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 835 !is_power_of_2(KMALLOC_MIN_SIZE)); 836 837 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 838 unsigned int elem = size_index_elem(i); 839 840 if (elem >= ARRAY_SIZE(size_index)) 841 break; 842 size_index[elem] = KMALLOC_SHIFT_LOW; 843 } 844 845 if (KMALLOC_MIN_SIZE >= 64) { 846 /* 847 * The 96 byte sized cache is not used if the alignment 848 * is 64 byte. 849 */ 850 for (i = 64 + 8; i <= 96; i += 8) 851 size_index[size_index_elem(i)] = 7; 852 853 } 854 855 if (KMALLOC_MIN_SIZE >= 128) { 856 /* 857 * The 192 byte sized cache is not used if the alignment 858 * is 128 byte. Redirect kmalloc to use the 256 byte cache 859 * instead. 860 */ 861 for (i = 128 + 8; i <= 192; i += 8) 862 size_index[size_index_elem(i)] = 8; 863 } 864 } 865 866 static void __init 867 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 868 { 869 if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) { 870 flags |= SLAB_RECLAIM_ACCOUNT; 871 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 872 if (mem_cgroup_kmem_disabled()) { 873 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 874 return; 875 } 876 flags |= SLAB_ACCOUNT; 877 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 878 flags |= SLAB_CACHE_DMA; 879 } 880 881 kmalloc_caches[type][idx] = create_kmalloc_cache( 882 kmalloc_info[idx].name[type], 883 kmalloc_info[idx].size, flags, 0, 884 kmalloc_info[idx].size); 885 886 /* 887 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 888 * KMALLOC_NORMAL caches. 889 */ 890 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 891 kmalloc_caches[type][idx]->refcount = -1; 892 } 893 894 /* 895 * Create the kmalloc array. Some of the regular kmalloc arrays 896 * may already have been created because they were needed to 897 * enable allocations for slab creation. 898 */ 899 void __init create_kmalloc_caches(slab_flags_t flags) 900 { 901 int i; 902 enum kmalloc_cache_type type; 903 904 /* 905 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 906 */ 907 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 908 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 909 if (!kmalloc_caches[type][i]) 910 new_kmalloc_cache(i, type, flags); 911 912 /* 913 * Caches that are not of the two-to-the-power-of size. 914 * These have to be created immediately after the 915 * earlier power of two caches 916 */ 917 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 918 !kmalloc_caches[type][1]) 919 new_kmalloc_cache(1, type, flags); 920 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 921 !kmalloc_caches[type][2]) 922 new_kmalloc_cache(2, type, flags); 923 } 924 } 925 926 /* Kmalloc array is now usable */ 927 slab_state = UP; 928 } 929 930 void free_large_kmalloc(struct folio *folio, void *object) 931 { 932 unsigned int order = folio_order(folio); 933 934 if (WARN_ON_ONCE(order == 0)) 935 pr_warn_once("object pointer: 0x%p\n", object); 936 937 kmemleak_free(object); 938 kasan_kfree_large(object); 939 kmsan_kfree_large(object); 940 941 mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B, 942 -(PAGE_SIZE << order)); 943 __free_pages(folio_page(folio, 0), order); 944 } 945 946 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node); 947 static __always_inline 948 void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) 949 { 950 struct kmem_cache *s; 951 void *ret; 952 953 if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { 954 ret = __kmalloc_large_node(size, flags, node); 955 trace_kmalloc(caller, ret, size, 956 PAGE_SIZE << get_order(size), flags, node); 957 return ret; 958 } 959 960 s = kmalloc_slab(size, flags); 961 962 if (unlikely(ZERO_OR_NULL_PTR(s))) 963 return s; 964 965 ret = __kmem_cache_alloc_node(s, flags, node, size, caller); 966 ret = kasan_kmalloc(s, ret, size, flags); 967 trace_kmalloc(caller, ret, size, s->size, flags, node); 968 return ret; 969 } 970 971 void *__kmalloc_node(size_t size, gfp_t flags, int node) 972 { 973 return __do_kmalloc_node(size, flags, node, _RET_IP_); 974 } 975 EXPORT_SYMBOL(__kmalloc_node); 976 977 void *__kmalloc(size_t size, gfp_t flags) 978 { 979 return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_); 980 } 981 EXPORT_SYMBOL(__kmalloc); 982 983 void *__kmalloc_node_track_caller(size_t size, gfp_t flags, 984 int node, unsigned long caller) 985 { 986 return __do_kmalloc_node(size, flags, node, caller); 987 } 988 EXPORT_SYMBOL(__kmalloc_node_track_caller); 989 990 /** 991 * kfree - free previously allocated memory 992 * @object: pointer returned by kmalloc() or kmem_cache_alloc() 993 * 994 * If @object is NULL, no operation is performed. 995 */ 996 void kfree(const void *object) 997 { 998 struct folio *folio; 999 struct slab *slab; 1000 struct kmem_cache *s; 1001 1002 trace_kfree(_RET_IP_, object); 1003 1004 if (unlikely(ZERO_OR_NULL_PTR(object))) 1005 return; 1006 1007 folio = virt_to_folio(object); 1008 if (unlikely(!folio_test_slab(folio))) { 1009 free_large_kmalloc(folio, (void *)object); 1010 return; 1011 } 1012 1013 slab = folio_slab(folio); 1014 s = slab->slab_cache; 1015 __kmem_cache_free(s, (void *)object, _RET_IP_); 1016 } 1017 EXPORT_SYMBOL(kfree); 1018 1019 /** 1020 * __ksize -- Report full size of underlying allocation 1021 * @object: pointer to the object 1022 * 1023 * This should only be used internally to query the true size of allocations. 1024 * It is not meant to be a way to discover the usable size of an allocation 1025 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond 1026 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS, 1027 * and/or FORTIFY_SOURCE. 1028 * 1029 * Return: size of the actual memory used by @object in bytes 1030 */ 1031 size_t __ksize(const void *object) 1032 { 1033 struct folio *folio; 1034 1035 if (unlikely(object == ZERO_SIZE_PTR)) 1036 return 0; 1037 1038 folio = virt_to_folio(object); 1039 1040 if (unlikely(!folio_test_slab(folio))) { 1041 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) 1042 return 0; 1043 if (WARN_ON(object != folio_address(folio))) 1044 return 0; 1045 return folio_size(folio); 1046 } 1047 1048 #ifdef CONFIG_SLUB_DEBUG 1049 skip_orig_size_check(folio_slab(folio)->slab_cache, object); 1050 #endif 1051 1052 return slab_ksize(folio_slab(folio)->slab_cache); 1053 } 1054 1055 void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) 1056 { 1057 void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE, 1058 size, _RET_IP_); 1059 1060 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE); 1061 1062 ret = kasan_kmalloc(s, ret, size, gfpflags); 1063 return ret; 1064 } 1065 EXPORT_SYMBOL(kmalloc_trace); 1066 1067 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, 1068 int node, size_t size) 1069 { 1070 void *ret = __kmem_cache_alloc_node(s, gfpflags, node, size, _RET_IP_); 1071 1072 trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node); 1073 1074 ret = kasan_kmalloc(s, ret, size, gfpflags); 1075 return ret; 1076 } 1077 EXPORT_SYMBOL(kmalloc_node_trace); 1078 1079 gfp_t kmalloc_fix_flags(gfp_t flags) 1080 { 1081 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 1082 1083 flags &= ~GFP_SLAB_BUG_MASK; 1084 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 1085 invalid_mask, &invalid_mask, flags, &flags); 1086 dump_stack(); 1087 1088 return flags; 1089 } 1090 1091 /* 1092 * To avoid unnecessary overhead, we pass through large allocation requests 1093 * directly to the page allocator. We use __GFP_COMP, because we will need to 1094 * know the allocation order to free the pages properly in kfree. 1095 */ 1096 1097 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node) 1098 { 1099 struct page *page; 1100 void *ptr = NULL; 1101 unsigned int order = get_order(size); 1102 1103 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 1104 flags = kmalloc_fix_flags(flags); 1105 1106 flags |= __GFP_COMP; 1107 page = alloc_pages_node(node, flags, order); 1108 if (page) { 1109 ptr = page_address(page); 1110 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 1111 PAGE_SIZE << order); 1112 } 1113 1114 ptr = kasan_kmalloc_large(ptr, size, flags); 1115 /* As ptr might get tagged, call kmemleak hook after KASAN. */ 1116 kmemleak_alloc(ptr, size, 1, flags); 1117 kmsan_kmalloc_large(ptr, size, flags); 1118 1119 return ptr; 1120 } 1121 1122 void *kmalloc_large(size_t size, gfp_t flags) 1123 { 1124 void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE); 1125 1126 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1127 flags, NUMA_NO_NODE); 1128 return ret; 1129 } 1130 EXPORT_SYMBOL(kmalloc_large); 1131 1132 void *kmalloc_large_node(size_t size, gfp_t flags, int node) 1133 { 1134 void *ret = __kmalloc_large_node(size, flags, node); 1135 1136 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), 1137 flags, node); 1138 return ret; 1139 } 1140 EXPORT_SYMBOL(kmalloc_large_node); 1141 1142 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1143 /* Randomize a generic freelist */ 1144 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 1145 unsigned int count) 1146 { 1147 unsigned int rand; 1148 unsigned int i; 1149 1150 for (i = 0; i < count; i++) 1151 list[i] = i; 1152 1153 /* Fisher-Yates shuffle */ 1154 for (i = count - 1; i > 0; i--) { 1155 rand = prandom_u32_state(state); 1156 rand %= (i + 1); 1157 swap(list[i], list[rand]); 1158 } 1159 } 1160 1161 /* Create a random sequence per cache */ 1162 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1163 gfp_t gfp) 1164 { 1165 struct rnd_state state; 1166 1167 if (count < 2 || cachep->random_seq) 1168 return 0; 1169 1170 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1171 if (!cachep->random_seq) 1172 return -ENOMEM; 1173 1174 /* Get best entropy at this stage of boot */ 1175 prandom_seed_state(&state, get_random_long()); 1176 1177 freelist_randomize(&state, cachep->random_seq, count); 1178 return 0; 1179 } 1180 1181 /* Destroy the per-cache random freelist sequence */ 1182 void cache_random_seq_destroy(struct kmem_cache *cachep) 1183 { 1184 kfree(cachep->random_seq); 1185 cachep->random_seq = NULL; 1186 } 1187 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1188 1189 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 1190 #ifdef CONFIG_SLAB 1191 #define SLABINFO_RIGHTS (0600) 1192 #else 1193 #define SLABINFO_RIGHTS (0400) 1194 #endif 1195 1196 static void print_slabinfo_header(struct seq_file *m) 1197 { 1198 /* 1199 * Output format version, so at least we can change it 1200 * without _too_ many complaints. 1201 */ 1202 #ifdef CONFIG_DEBUG_SLAB 1203 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1204 #else 1205 seq_puts(m, "slabinfo - version: 2.1\n"); 1206 #endif 1207 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1208 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1209 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1210 #ifdef CONFIG_DEBUG_SLAB 1211 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1212 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1213 #endif 1214 seq_putc(m, '\n'); 1215 } 1216 1217 static void *slab_start(struct seq_file *m, loff_t *pos) 1218 { 1219 mutex_lock(&slab_mutex); 1220 return seq_list_start(&slab_caches, *pos); 1221 } 1222 1223 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1224 { 1225 return seq_list_next(p, &slab_caches, pos); 1226 } 1227 1228 static void slab_stop(struct seq_file *m, void *p) 1229 { 1230 mutex_unlock(&slab_mutex); 1231 } 1232 1233 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1234 { 1235 struct slabinfo sinfo; 1236 1237 memset(&sinfo, 0, sizeof(sinfo)); 1238 get_slabinfo(s, &sinfo); 1239 1240 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1241 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1242 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1243 1244 seq_printf(m, " : tunables %4u %4u %4u", 1245 sinfo.limit, sinfo.batchcount, sinfo.shared); 1246 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1247 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1248 slabinfo_show_stats(m, s); 1249 seq_putc(m, '\n'); 1250 } 1251 1252 static int slab_show(struct seq_file *m, void *p) 1253 { 1254 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1255 1256 if (p == slab_caches.next) 1257 print_slabinfo_header(m); 1258 cache_show(s, m); 1259 return 0; 1260 } 1261 1262 void dump_unreclaimable_slab(void) 1263 { 1264 struct kmem_cache *s; 1265 struct slabinfo sinfo; 1266 1267 /* 1268 * Here acquiring slab_mutex is risky since we don't prefer to get 1269 * sleep in oom path. But, without mutex hold, it may introduce a 1270 * risk of crash. 1271 * Use mutex_trylock to protect the list traverse, dump nothing 1272 * without acquiring the mutex. 1273 */ 1274 if (!mutex_trylock(&slab_mutex)) { 1275 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1276 return; 1277 } 1278 1279 pr_info("Unreclaimable slab info:\n"); 1280 pr_info("Name Used Total\n"); 1281 1282 list_for_each_entry(s, &slab_caches, list) { 1283 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1284 continue; 1285 1286 get_slabinfo(s, &sinfo); 1287 1288 if (sinfo.num_objs > 0) 1289 pr_info("%-17s %10luKB %10luKB\n", s->name, 1290 (sinfo.active_objs * s->size) / 1024, 1291 (sinfo.num_objs * s->size) / 1024); 1292 } 1293 mutex_unlock(&slab_mutex); 1294 } 1295 1296 /* 1297 * slabinfo_op - iterator that generates /proc/slabinfo 1298 * 1299 * Output layout: 1300 * cache-name 1301 * num-active-objs 1302 * total-objs 1303 * object size 1304 * num-active-slabs 1305 * total-slabs 1306 * num-pages-per-slab 1307 * + further values on SMP and with statistics enabled 1308 */ 1309 static const struct seq_operations slabinfo_op = { 1310 .start = slab_start, 1311 .next = slab_next, 1312 .stop = slab_stop, 1313 .show = slab_show, 1314 }; 1315 1316 static int slabinfo_open(struct inode *inode, struct file *file) 1317 { 1318 return seq_open(file, &slabinfo_op); 1319 } 1320 1321 static const struct proc_ops slabinfo_proc_ops = { 1322 .proc_flags = PROC_ENTRY_PERMANENT, 1323 .proc_open = slabinfo_open, 1324 .proc_read = seq_read, 1325 .proc_write = slabinfo_write, 1326 .proc_lseek = seq_lseek, 1327 .proc_release = seq_release, 1328 }; 1329 1330 static int __init slab_proc_init(void) 1331 { 1332 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1333 return 0; 1334 } 1335 module_init(slab_proc_init); 1336 1337 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1338 1339 static __always_inline __realloc_size(2) void * 1340 __do_krealloc(const void *p, size_t new_size, gfp_t flags) 1341 { 1342 void *ret; 1343 size_t ks; 1344 1345 /* Check for double-free before calling ksize. */ 1346 if (likely(!ZERO_OR_NULL_PTR(p))) { 1347 if (!kasan_check_byte(p)) 1348 return NULL; 1349 ks = ksize(p); 1350 } else 1351 ks = 0; 1352 1353 /* If the object still fits, repoison it precisely. */ 1354 if (ks >= new_size) { 1355 p = kasan_krealloc((void *)p, new_size, flags); 1356 return (void *)p; 1357 } 1358 1359 ret = kmalloc_track_caller(new_size, flags); 1360 if (ret && p) { 1361 /* Disable KASAN checks as the object's redzone is accessed. */ 1362 kasan_disable_current(); 1363 memcpy(ret, kasan_reset_tag(p), ks); 1364 kasan_enable_current(); 1365 } 1366 1367 return ret; 1368 } 1369 1370 /** 1371 * krealloc - reallocate memory. The contents will remain unchanged. 1372 * @p: object to reallocate memory for. 1373 * @new_size: how many bytes of memory are required. 1374 * @flags: the type of memory to allocate. 1375 * 1376 * The contents of the object pointed to are preserved up to the 1377 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1378 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1379 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1380 * 1381 * Return: pointer to the allocated memory or %NULL in case of error 1382 */ 1383 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1384 { 1385 void *ret; 1386 1387 if (unlikely(!new_size)) { 1388 kfree(p); 1389 return ZERO_SIZE_PTR; 1390 } 1391 1392 ret = __do_krealloc(p, new_size, flags); 1393 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1394 kfree(p); 1395 1396 return ret; 1397 } 1398 EXPORT_SYMBOL(krealloc); 1399 1400 /** 1401 * kfree_sensitive - Clear sensitive information in memory before freeing 1402 * @p: object to free memory of 1403 * 1404 * The memory of the object @p points to is zeroed before freed. 1405 * If @p is %NULL, kfree_sensitive() does nothing. 1406 * 1407 * Note: this function zeroes the whole allocated buffer which can be a good 1408 * deal bigger than the requested buffer size passed to kmalloc(). So be 1409 * careful when using this function in performance sensitive code. 1410 */ 1411 void kfree_sensitive(const void *p) 1412 { 1413 size_t ks; 1414 void *mem = (void *)p; 1415 1416 ks = ksize(mem); 1417 if (ks) { 1418 kasan_unpoison_range(mem, ks); 1419 memzero_explicit(mem, ks); 1420 } 1421 kfree(mem); 1422 } 1423 EXPORT_SYMBOL(kfree_sensitive); 1424 1425 size_t ksize(const void *objp) 1426 { 1427 /* 1428 * We need to first check that the pointer to the object is valid. 1429 * The KASAN report printed from ksize() is more useful, then when 1430 * it's printed later when the behaviour could be undefined due to 1431 * a potential use-after-free or double-free. 1432 * 1433 * We use kasan_check_byte(), which is supported for the hardware 1434 * tag-based KASAN mode, unlike kasan_check_read/write(). 1435 * 1436 * If the pointed to memory is invalid, we return 0 to avoid users of 1437 * ksize() writing to and potentially corrupting the memory region. 1438 * 1439 * We want to perform the check before __ksize(), to avoid potentially 1440 * crashing in __ksize() due to accessing invalid metadata. 1441 */ 1442 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1443 return 0; 1444 1445 return kfence_ksize(objp) ?: __ksize(objp); 1446 } 1447 EXPORT_SYMBOL(ksize); 1448 1449 /* Tracepoints definitions. */ 1450 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1451 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1452 EXPORT_TRACEPOINT_SYMBOL(kfree); 1453 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1454 1455 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1456 { 1457 if (__should_failslab(s, gfpflags)) 1458 return -ENOMEM; 1459 return 0; 1460 } 1461 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1462