1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Slab allocator functions that are independent of the allocator strategy 4 * 5 * (C) 2012 Christoph Lameter <cl@linux.com> 6 */ 7 #include <linux/slab.h> 8 9 #include <linux/mm.h> 10 #include <linux/poison.h> 11 #include <linux/interrupt.h> 12 #include <linux/memory.h> 13 #include <linux/cache.h> 14 #include <linux/compiler.h> 15 #include <linux/kfence.h> 16 #include <linux/module.h> 17 #include <linux/cpu.h> 18 #include <linux/uaccess.h> 19 #include <linux/seq_file.h> 20 #include <linux/proc_fs.h> 21 #include <linux/debugfs.h> 22 #include <linux/kasan.h> 23 #include <asm/cacheflush.h> 24 #include <asm/tlbflush.h> 25 #include <asm/page.h> 26 #include <linux/memcontrol.h> 27 #include <linux/stackdepot.h> 28 29 #include "internal.h" 30 #include "slab.h" 31 32 #define CREATE_TRACE_POINTS 33 #include <trace/events/kmem.h> 34 35 enum slab_state slab_state; 36 LIST_HEAD(slab_caches); 37 DEFINE_MUTEX(slab_mutex); 38 struct kmem_cache *kmem_cache; 39 40 static LIST_HEAD(slab_caches_to_rcu_destroy); 41 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 42 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 43 slab_caches_to_rcu_destroy_workfn); 44 45 /* 46 * Set of flags that will prevent slab merging 47 */ 48 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 49 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 50 SLAB_FAILSLAB | kasan_never_merge()) 51 52 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 53 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 54 55 /* 56 * Merge control. If this is set then no merging of slab caches will occur. 57 */ 58 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 59 60 static int __init setup_slab_nomerge(char *str) 61 { 62 slab_nomerge = true; 63 return 1; 64 } 65 66 static int __init setup_slab_merge(char *str) 67 { 68 slab_nomerge = false; 69 return 1; 70 } 71 72 #ifdef CONFIG_SLUB 73 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 74 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0); 75 #endif 76 77 __setup("slab_nomerge", setup_slab_nomerge); 78 __setup("slab_merge", setup_slab_merge); 79 80 /* 81 * Determine the size of a slab object 82 */ 83 unsigned int kmem_cache_size(struct kmem_cache *s) 84 { 85 return s->object_size; 86 } 87 EXPORT_SYMBOL(kmem_cache_size); 88 89 #ifdef CONFIG_DEBUG_VM 90 static int kmem_cache_sanity_check(const char *name, unsigned int size) 91 { 92 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { 93 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 94 return -EINVAL; 95 } 96 97 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 98 return 0; 99 } 100 #else 101 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 102 { 103 return 0; 104 } 105 #endif 106 107 /* 108 * Figure out what the alignment of the objects will be given a set of 109 * flags, a user specified alignment and the size of the objects. 110 */ 111 static unsigned int calculate_alignment(slab_flags_t flags, 112 unsigned int align, unsigned int size) 113 { 114 /* 115 * If the user wants hardware cache aligned objects then follow that 116 * suggestion if the object is sufficiently large. 117 * 118 * The hardware cache alignment cannot override the specified 119 * alignment though. If that is greater then use it. 120 */ 121 if (flags & SLAB_HWCACHE_ALIGN) { 122 unsigned int ralign; 123 124 ralign = cache_line_size(); 125 while (size <= ralign / 2) 126 ralign /= 2; 127 align = max(align, ralign); 128 } 129 130 align = max(align, arch_slab_minalign()); 131 132 return ALIGN(align, sizeof(void *)); 133 } 134 135 /* 136 * Find a mergeable slab cache 137 */ 138 int slab_unmergeable(struct kmem_cache *s) 139 { 140 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 141 return 1; 142 143 if (s->ctor) 144 return 1; 145 146 if (s->usersize) 147 return 1; 148 149 /* 150 * We may have set a slab to be unmergeable during bootstrap. 151 */ 152 if (s->refcount < 0) 153 return 1; 154 155 return 0; 156 } 157 158 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 159 slab_flags_t flags, const char *name, void (*ctor)(void *)) 160 { 161 struct kmem_cache *s; 162 163 if (slab_nomerge) 164 return NULL; 165 166 if (ctor) 167 return NULL; 168 169 size = ALIGN(size, sizeof(void *)); 170 align = calculate_alignment(flags, align, size); 171 size = ALIGN(size, align); 172 flags = kmem_cache_flags(size, flags, name); 173 174 if (flags & SLAB_NEVER_MERGE) 175 return NULL; 176 177 list_for_each_entry_reverse(s, &slab_caches, list) { 178 if (slab_unmergeable(s)) 179 continue; 180 181 if (size > s->size) 182 continue; 183 184 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 185 continue; 186 /* 187 * Check if alignment is compatible. 188 * Courtesy of Adrian Drzewiecki 189 */ 190 if ((s->size & ~(align - 1)) != s->size) 191 continue; 192 193 if (s->size - size >= sizeof(void *)) 194 continue; 195 196 if (IS_ENABLED(CONFIG_SLAB) && align && 197 (align > s->align || s->align % align)) 198 continue; 199 200 return s; 201 } 202 return NULL; 203 } 204 205 static struct kmem_cache *create_cache(const char *name, 206 unsigned int object_size, unsigned int align, 207 slab_flags_t flags, unsigned int useroffset, 208 unsigned int usersize, void (*ctor)(void *), 209 struct kmem_cache *root_cache) 210 { 211 struct kmem_cache *s; 212 int err; 213 214 if (WARN_ON(useroffset + usersize > object_size)) 215 useroffset = usersize = 0; 216 217 err = -ENOMEM; 218 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 219 if (!s) 220 goto out; 221 222 s->name = name; 223 s->size = s->object_size = object_size; 224 s->align = align; 225 s->ctor = ctor; 226 s->useroffset = useroffset; 227 s->usersize = usersize; 228 229 err = __kmem_cache_create(s, flags); 230 if (err) 231 goto out_free_cache; 232 233 s->refcount = 1; 234 list_add(&s->list, &slab_caches); 235 out: 236 if (err) 237 return ERR_PTR(err); 238 return s; 239 240 out_free_cache: 241 kmem_cache_free(kmem_cache, s); 242 goto out; 243 } 244 245 /** 246 * kmem_cache_create_usercopy - Create a cache with a region suitable 247 * for copying to userspace 248 * @name: A string which is used in /proc/slabinfo to identify this cache. 249 * @size: The size of objects to be created in this cache. 250 * @align: The required alignment for the objects. 251 * @flags: SLAB flags 252 * @useroffset: Usercopy region offset 253 * @usersize: Usercopy region size 254 * @ctor: A constructor for the objects. 255 * 256 * Cannot be called within a interrupt, but can be interrupted. 257 * The @ctor is run when new pages are allocated by the cache. 258 * 259 * The flags are 260 * 261 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 262 * to catch references to uninitialised memory. 263 * 264 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 265 * for buffer overruns. 266 * 267 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 268 * cacheline. This can be beneficial if you're counting cycles as closely 269 * as davem. 270 * 271 * Return: a pointer to the cache on success, NULL on failure. 272 */ 273 struct kmem_cache * 274 kmem_cache_create_usercopy(const char *name, 275 unsigned int size, unsigned int align, 276 slab_flags_t flags, 277 unsigned int useroffset, unsigned int usersize, 278 void (*ctor)(void *)) 279 { 280 struct kmem_cache *s = NULL; 281 const char *cache_name; 282 int err; 283 284 #ifdef CONFIG_SLUB_DEBUG 285 /* 286 * If no slub_debug was enabled globally, the static key is not yet 287 * enabled by setup_slub_debug(). Enable it if the cache is being 288 * created with any of the debugging flags passed explicitly. 289 * It's also possible that this is the first cache created with 290 * SLAB_STORE_USER and we should init stack_depot for it. 291 */ 292 if (flags & SLAB_DEBUG_FLAGS) 293 static_branch_enable(&slub_debug_enabled); 294 if (flags & SLAB_STORE_USER) 295 stack_depot_init(); 296 #endif 297 298 mutex_lock(&slab_mutex); 299 300 err = kmem_cache_sanity_check(name, size); 301 if (err) { 302 goto out_unlock; 303 } 304 305 /* Refuse requests with allocator specific flags */ 306 if (flags & ~SLAB_FLAGS_PERMITTED) { 307 err = -EINVAL; 308 goto out_unlock; 309 } 310 311 /* 312 * Some allocators will constraint the set of valid flags to a subset 313 * of all flags. We expect them to define CACHE_CREATE_MASK in this 314 * case, and we'll just provide them with a sanitized version of the 315 * passed flags. 316 */ 317 flags &= CACHE_CREATE_MASK; 318 319 /* Fail closed on bad usersize of useroffset values. */ 320 if (WARN_ON(!usersize && useroffset) || 321 WARN_ON(size < usersize || size - usersize < useroffset)) 322 usersize = useroffset = 0; 323 324 if (!usersize) 325 s = __kmem_cache_alias(name, size, align, flags, ctor); 326 if (s) 327 goto out_unlock; 328 329 cache_name = kstrdup_const(name, GFP_KERNEL); 330 if (!cache_name) { 331 err = -ENOMEM; 332 goto out_unlock; 333 } 334 335 s = create_cache(cache_name, size, 336 calculate_alignment(flags, align, size), 337 flags, useroffset, usersize, ctor, NULL); 338 if (IS_ERR(s)) { 339 err = PTR_ERR(s); 340 kfree_const(cache_name); 341 } 342 343 out_unlock: 344 mutex_unlock(&slab_mutex); 345 346 if (err) { 347 if (flags & SLAB_PANIC) 348 panic("%s: Failed to create slab '%s'. Error %d\n", 349 __func__, name, err); 350 else { 351 pr_warn("%s(%s) failed with error %d\n", 352 __func__, name, err); 353 dump_stack(); 354 } 355 return NULL; 356 } 357 return s; 358 } 359 EXPORT_SYMBOL(kmem_cache_create_usercopy); 360 361 /** 362 * kmem_cache_create - Create a cache. 363 * @name: A string which is used in /proc/slabinfo to identify this cache. 364 * @size: The size of objects to be created in this cache. 365 * @align: The required alignment for the objects. 366 * @flags: SLAB flags 367 * @ctor: A constructor for the objects. 368 * 369 * Cannot be called within a interrupt, but can be interrupted. 370 * The @ctor is run when new pages are allocated by the cache. 371 * 372 * The flags are 373 * 374 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 375 * to catch references to uninitialised memory. 376 * 377 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 378 * for buffer overruns. 379 * 380 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 381 * cacheline. This can be beneficial if you're counting cycles as closely 382 * as davem. 383 * 384 * Return: a pointer to the cache on success, NULL on failure. 385 */ 386 struct kmem_cache * 387 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 388 slab_flags_t flags, void (*ctor)(void *)) 389 { 390 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 391 ctor); 392 } 393 EXPORT_SYMBOL(kmem_cache_create); 394 395 #ifdef SLAB_SUPPORTS_SYSFS 396 /* 397 * For a given kmem_cache, kmem_cache_destroy() should only be called 398 * once or there will be a use-after-free problem. The actual deletion 399 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock 400 * protection. So they are now done without holding those locks. 401 * 402 * Note that there will be a slight delay in the deletion of sysfs files 403 * if kmem_cache_release() is called indrectly from a work function. 404 */ 405 static void kmem_cache_release(struct kmem_cache *s) 406 { 407 sysfs_slab_unlink(s); 408 sysfs_slab_release(s); 409 } 410 #else 411 static void kmem_cache_release(struct kmem_cache *s) 412 { 413 slab_kmem_cache_release(s); 414 } 415 #endif 416 417 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 418 { 419 LIST_HEAD(to_destroy); 420 struct kmem_cache *s, *s2; 421 422 /* 423 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 424 * @slab_caches_to_rcu_destroy list. The slab pages are freed 425 * through RCU and the associated kmem_cache are dereferenced 426 * while freeing the pages, so the kmem_caches should be freed only 427 * after the pending RCU operations are finished. As rcu_barrier() 428 * is a pretty slow operation, we batch all pending destructions 429 * asynchronously. 430 */ 431 mutex_lock(&slab_mutex); 432 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 433 mutex_unlock(&slab_mutex); 434 435 if (list_empty(&to_destroy)) 436 return; 437 438 rcu_barrier(); 439 440 list_for_each_entry_safe(s, s2, &to_destroy, list) { 441 debugfs_slab_release(s); 442 kfence_shutdown_cache(s); 443 kmem_cache_release(s); 444 } 445 } 446 447 static int shutdown_cache(struct kmem_cache *s) 448 { 449 /* free asan quarantined objects */ 450 kasan_cache_shutdown(s); 451 452 if (__kmem_cache_shutdown(s) != 0) 453 return -EBUSY; 454 455 list_del(&s->list); 456 457 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 458 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 459 schedule_work(&slab_caches_to_rcu_destroy_work); 460 } else { 461 kfence_shutdown_cache(s); 462 debugfs_slab_release(s); 463 } 464 465 return 0; 466 } 467 468 void slab_kmem_cache_release(struct kmem_cache *s) 469 { 470 __kmem_cache_release(s); 471 kfree_const(s->name); 472 kmem_cache_free(kmem_cache, s); 473 } 474 475 void kmem_cache_destroy(struct kmem_cache *s) 476 { 477 int refcnt; 478 bool rcu_set; 479 480 if (unlikely(!s) || !kasan_check_byte(s)) 481 return; 482 483 cpus_read_lock(); 484 mutex_lock(&slab_mutex); 485 486 rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; 487 488 refcnt = --s->refcount; 489 if (refcnt) 490 goto out_unlock; 491 492 WARN(shutdown_cache(s), 493 "%s %s: Slab cache still has objects when called from %pS", 494 __func__, s->name, (void *)_RET_IP_); 495 out_unlock: 496 mutex_unlock(&slab_mutex); 497 cpus_read_unlock(); 498 if (!refcnt && !rcu_set) 499 kmem_cache_release(s); 500 } 501 EXPORT_SYMBOL(kmem_cache_destroy); 502 503 /** 504 * kmem_cache_shrink - Shrink a cache. 505 * @cachep: The cache to shrink. 506 * 507 * Releases as many slabs as possible for a cache. 508 * To help debugging, a zero exit status indicates all slabs were released. 509 * 510 * Return: %0 if all slabs were released, non-zero otherwise 511 */ 512 int kmem_cache_shrink(struct kmem_cache *cachep) 513 { 514 int ret; 515 516 517 kasan_cache_shrink(cachep); 518 ret = __kmem_cache_shrink(cachep); 519 520 return ret; 521 } 522 EXPORT_SYMBOL(kmem_cache_shrink); 523 524 bool slab_is_available(void) 525 { 526 return slab_state >= UP; 527 } 528 529 #ifdef CONFIG_PRINTK 530 /** 531 * kmem_valid_obj - does the pointer reference a valid slab object? 532 * @object: pointer to query. 533 * 534 * Return: %true if the pointer is to a not-yet-freed object from 535 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 536 * is to an already-freed object, and %false otherwise. 537 */ 538 bool kmem_valid_obj(void *object) 539 { 540 struct folio *folio; 541 542 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 543 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 544 return false; 545 folio = virt_to_folio(object); 546 return folio_test_slab(folio); 547 } 548 EXPORT_SYMBOL_GPL(kmem_valid_obj); 549 550 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 551 { 552 if (__kfence_obj_info(kpp, object, slab)) 553 return; 554 __kmem_obj_info(kpp, object, slab); 555 } 556 557 /** 558 * kmem_dump_obj - Print available slab provenance information 559 * @object: slab object for which to find provenance information. 560 * 561 * This function uses pr_cont(), so that the caller is expected to have 562 * printed out whatever preamble is appropriate. The provenance information 563 * depends on the type of object and on how much debugging is enabled. 564 * For a slab-cache object, the fact that it is a slab object is printed, 565 * and, if available, the slab name, return address, and stack trace from 566 * the allocation and last free path of that object. 567 * 568 * This function will splat if passed a pointer to a non-slab object. 569 * If you are not sure what type of object you have, you should instead 570 * use mem_dump_obj(). 571 */ 572 void kmem_dump_obj(void *object) 573 { 574 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 575 int i; 576 struct slab *slab; 577 unsigned long ptroffset; 578 struct kmem_obj_info kp = { }; 579 580 if (WARN_ON_ONCE(!virt_addr_valid(object))) 581 return; 582 slab = virt_to_slab(object); 583 if (WARN_ON_ONCE(!slab)) { 584 pr_cont(" non-slab memory.\n"); 585 return; 586 } 587 kmem_obj_info(&kp, object, slab); 588 if (kp.kp_slab_cache) 589 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 590 else 591 pr_cont(" slab%s", cp); 592 if (is_kfence_address(object)) 593 pr_cont(" (kfence)"); 594 if (kp.kp_objp) 595 pr_cont(" start %px", kp.kp_objp); 596 if (kp.kp_data_offset) 597 pr_cont(" data offset %lu", kp.kp_data_offset); 598 if (kp.kp_objp) { 599 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 600 pr_cont(" pointer offset %lu", ptroffset); 601 } 602 if (kp.kp_slab_cache && kp.kp_slab_cache->usersize) 603 pr_cont(" size %u", kp.kp_slab_cache->usersize); 604 if (kp.kp_ret) 605 pr_cont(" allocated at %pS\n", kp.kp_ret); 606 else 607 pr_cont("\n"); 608 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 609 if (!kp.kp_stack[i]) 610 break; 611 pr_info(" %pS\n", kp.kp_stack[i]); 612 } 613 614 if (kp.kp_free_stack[0]) 615 pr_cont(" Free path:\n"); 616 617 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 618 if (!kp.kp_free_stack[i]) 619 break; 620 pr_info(" %pS\n", kp.kp_free_stack[i]); 621 } 622 623 } 624 EXPORT_SYMBOL_GPL(kmem_dump_obj); 625 #endif 626 627 #ifndef CONFIG_SLOB 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 s->useroffset = useroffset; 648 s->usersize = usersize; 649 650 err = __kmem_cache_create(s, flags); 651 652 if (err) 653 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 654 name, size, err); 655 656 s->refcount = -1; /* Exempt from merging for now */ 657 } 658 659 struct kmem_cache *__init create_kmalloc_cache(const char *name, 660 unsigned int size, slab_flags_t flags, 661 unsigned int useroffset, unsigned int usersize) 662 { 663 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 664 665 if (!s) 666 panic("Out of memory when creating slab %s\n", name); 667 668 create_boot_cache(s, name, size, flags, useroffset, usersize); 669 kasan_cache_create_kmalloc(s); 670 list_add(&s->list, &slab_caches); 671 s->refcount = 1; 672 return s; 673 } 674 675 struct kmem_cache * 676 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 677 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 678 EXPORT_SYMBOL(kmalloc_caches); 679 680 /* 681 * Conversion table for small slabs sizes / 8 to the index in the 682 * kmalloc array. This is necessary for slabs < 192 since we have non power 683 * of two cache sizes there. The size of larger slabs can be determined using 684 * fls. 685 */ 686 static u8 size_index[24] __ro_after_init = { 687 3, /* 8 */ 688 4, /* 16 */ 689 5, /* 24 */ 690 5, /* 32 */ 691 6, /* 40 */ 692 6, /* 48 */ 693 6, /* 56 */ 694 6, /* 64 */ 695 1, /* 72 */ 696 1, /* 80 */ 697 1, /* 88 */ 698 1, /* 96 */ 699 7, /* 104 */ 700 7, /* 112 */ 701 7, /* 120 */ 702 7, /* 128 */ 703 2, /* 136 */ 704 2, /* 144 */ 705 2, /* 152 */ 706 2, /* 160 */ 707 2, /* 168 */ 708 2, /* 176 */ 709 2, /* 184 */ 710 2 /* 192 */ 711 }; 712 713 static inline unsigned int size_index_elem(unsigned int bytes) 714 { 715 return (bytes - 1) / 8; 716 } 717 718 /* 719 * Find the kmem_cache structure that serves a given size of 720 * allocation 721 */ 722 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 723 { 724 unsigned int index; 725 726 if (size <= 192) { 727 if (!size) 728 return ZERO_SIZE_PTR; 729 730 index = size_index[size_index_elem(size)]; 731 } else { 732 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 733 return NULL; 734 index = fls(size - 1); 735 } 736 737 return kmalloc_caches[kmalloc_type(flags)][index]; 738 } 739 740 #ifdef CONFIG_ZONE_DMA 741 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 742 #else 743 #define KMALLOC_DMA_NAME(sz) 744 #endif 745 746 #ifdef CONFIG_MEMCG_KMEM 747 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 748 #else 749 #define KMALLOC_CGROUP_NAME(sz) 750 #endif 751 752 #define INIT_KMALLOC_INFO(__size, __short_size) \ 753 { \ 754 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 755 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 756 KMALLOC_CGROUP_NAME(__short_size) \ 757 KMALLOC_DMA_NAME(__short_size) \ 758 .size = __size, \ 759 } 760 761 /* 762 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 763 * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is 764 * kmalloc-32M. 765 */ 766 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 767 INIT_KMALLOC_INFO(0, 0), 768 INIT_KMALLOC_INFO(96, 96), 769 INIT_KMALLOC_INFO(192, 192), 770 INIT_KMALLOC_INFO(8, 8), 771 INIT_KMALLOC_INFO(16, 16), 772 INIT_KMALLOC_INFO(32, 32), 773 INIT_KMALLOC_INFO(64, 64), 774 INIT_KMALLOC_INFO(128, 128), 775 INIT_KMALLOC_INFO(256, 256), 776 INIT_KMALLOC_INFO(512, 512), 777 INIT_KMALLOC_INFO(1024, 1k), 778 INIT_KMALLOC_INFO(2048, 2k), 779 INIT_KMALLOC_INFO(4096, 4k), 780 INIT_KMALLOC_INFO(8192, 8k), 781 INIT_KMALLOC_INFO(16384, 16k), 782 INIT_KMALLOC_INFO(32768, 32k), 783 INIT_KMALLOC_INFO(65536, 64k), 784 INIT_KMALLOC_INFO(131072, 128k), 785 INIT_KMALLOC_INFO(262144, 256k), 786 INIT_KMALLOC_INFO(524288, 512k), 787 INIT_KMALLOC_INFO(1048576, 1M), 788 INIT_KMALLOC_INFO(2097152, 2M), 789 INIT_KMALLOC_INFO(4194304, 4M), 790 INIT_KMALLOC_INFO(8388608, 8M), 791 INIT_KMALLOC_INFO(16777216, 16M), 792 INIT_KMALLOC_INFO(33554432, 32M) 793 }; 794 795 /* 796 * Patch up the size_index table if we have strange large alignment 797 * requirements for the kmalloc array. This is only the case for 798 * MIPS it seems. The standard arches will not generate any code here. 799 * 800 * Largest permitted alignment is 256 bytes due to the way we 801 * handle the index determination for the smaller caches. 802 * 803 * Make sure that nothing crazy happens if someone starts tinkering 804 * around with ARCH_KMALLOC_MINALIGN 805 */ 806 void __init setup_kmalloc_cache_index_table(void) 807 { 808 unsigned int i; 809 810 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 811 !is_power_of_2(KMALLOC_MIN_SIZE)); 812 813 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 814 unsigned int elem = size_index_elem(i); 815 816 if (elem >= ARRAY_SIZE(size_index)) 817 break; 818 size_index[elem] = KMALLOC_SHIFT_LOW; 819 } 820 821 if (KMALLOC_MIN_SIZE >= 64) { 822 /* 823 * The 96 byte sized cache is not used if the alignment 824 * is 64 byte. 825 */ 826 for (i = 64 + 8; i <= 96; i += 8) 827 size_index[size_index_elem(i)] = 7; 828 829 } 830 831 if (KMALLOC_MIN_SIZE >= 128) { 832 /* 833 * The 192 byte sized cache is not used if the alignment 834 * is 128 byte. Redirect kmalloc to use the 256 byte cache 835 * instead. 836 */ 837 for (i = 128 + 8; i <= 192; i += 8) 838 size_index[size_index_elem(i)] = 8; 839 } 840 } 841 842 static void __init 843 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 844 { 845 if (type == KMALLOC_RECLAIM) { 846 flags |= SLAB_RECLAIM_ACCOUNT; 847 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 848 if (mem_cgroup_kmem_disabled()) { 849 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 850 return; 851 } 852 flags |= SLAB_ACCOUNT; 853 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 854 flags |= SLAB_CACHE_DMA; 855 } 856 857 kmalloc_caches[type][idx] = create_kmalloc_cache( 858 kmalloc_info[idx].name[type], 859 kmalloc_info[idx].size, flags, 0, 860 kmalloc_info[idx].size); 861 862 /* 863 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 864 * KMALLOC_NORMAL caches. 865 */ 866 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 867 kmalloc_caches[type][idx]->refcount = -1; 868 } 869 870 /* 871 * Create the kmalloc array. Some of the regular kmalloc arrays 872 * may already have been created because they were needed to 873 * enable allocations for slab creation. 874 */ 875 void __init create_kmalloc_caches(slab_flags_t flags) 876 { 877 int i; 878 enum kmalloc_cache_type type; 879 880 /* 881 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 882 */ 883 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 884 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 885 if (!kmalloc_caches[type][i]) 886 new_kmalloc_cache(i, type, flags); 887 888 /* 889 * Caches that are not of the two-to-the-power-of size. 890 * These have to be created immediately after the 891 * earlier power of two caches 892 */ 893 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 894 !kmalloc_caches[type][1]) 895 new_kmalloc_cache(1, type, flags); 896 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 897 !kmalloc_caches[type][2]) 898 new_kmalloc_cache(2, type, flags); 899 } 900 } 901 902 /* Kmalloc array is now usable */ 903 slab_state = UP; 904 } 905 #endif /* !CONFIG_SLOB */ 906 907 gfp_t kmalloc_fix_flags(gfp_t flags) 908 { 909 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 910 911 flags &= ~GFP_SLAB_BUG_MASK; 912 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 913 invalid_mask, &invalid_mask, flags, &flags); 914 dump_stack(); 915 916 return flags; 917 } 918 919 /* 920 * To avoid unnecessary overhead, we pass through large allocation requests 921 * directly to the page allocator. We use __GFP_COMP, because we will need to 922 * know the allocation order to free the pages properly in kfree. 923 */ 924 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 925 { 926 void *ret = NULL; 927 struct page *page; 928 929 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 930 flags = kmalloc_fix_flags(flags); 931 932 flags |= __GFP_COMP; 933 page = alloc_pages(flags, order); 934 if (likely(page)) { 935 ret = page_address(page); 936 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 937 PAGE_SIZE << order); 938 } 939 ret = kasan_kmalloc_large(ret, size, flags); 940 /* As ret might get tagged, call kmemleak hook after KASAN. */ 941 kmemleak_alloc(ret, size, 1, flags); 942 return ret; 943 } 944 EXPORT_SYMBOL(kmalloc_order); 945 946 #ifdef CONFIG_TRACING 947 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 948 { 949 void *ret = kmalloc_order(size, flags, order); 950 trace_kmalloc(_RET_IP_, ret, NULL, size, PAGE_SIZE << order, flags); 951 return ret; 952 } 953 EXPORT_SYMBOL(kmalloc_order_trace); 954 #endif 955 956 #ifdef CONFIG_SLAB_FREELIST_RANDOM 957 /* Randomize a generic freelist */ 958 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 959 unsigned int count) 960 { 961 unsigned int rand; 962 unsigned int i; 963 964 for (i = 0; i < count; i++) 965 list[i] = i; 966 967 /* Fisher-Yates shuffle */ 968 for (i = count - 1; i > 0; i--) { 969 rand = prandom_u32_state(state); 970 rand %= (i + 1); 971 swap(list[i], list[rand]); 972 } 973 } 974 975 /* Create a random sequence per cache */ 976 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 977 gfp_t gfp) 978 { 979 struct rnd_state state; 980 981 if (count < 2 || cachep->random_seq) 982 return 0; 983 984 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 985 if (!cachep->random_seq) 986 return -ENOMEM; 987 988 /* Get best entropy at this stage of boot */ 989 prandom_seed_state(&state, get_random_long()); 990 991 freelist_randomize(&state, cachep->random_seq, count); 992 return 0; 993 } 994 995 /* Destroy the per-cache random freelist sequence */ 996 void cache_random_seq_destroy(struct kmem_cache *cachep) 997 { 998 kfree(cachep->random_seq); 999 cachep->random_seq = NULL; 1000 } 1001 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1002 1003 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 1004 #ifdef CONFIG_SLAB 1005 #define SLABINFO_RIGHTS (0600) 1006 #else 1007 #define SLABINFO_RIGHTS (0400) 1008 #endif 1009 1010 static void print_slabinfo_header(struct seq_file *m) 1011 { 1012 /* 1013 * Output format version, so at least we can change it 1014 * without _too_ many complaints. 1015 */ 1016 #ifdef CONFIG_DEBUG_SLAB 1017 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1018 #else 1019 seq_puts(m, "slabinfo - version: 2.1\n"); 1020 #endif 1021 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1022 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1023 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1024 #ifdef CONFIG_DEBUG_SLAB 1025 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1026 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1027 #endif 1028 seq_putc(m, '\n'); 1029 } 1030 1031 static void *slab_start(struct seq_file *m, loff_t *pos) 1032 { 1033 mutex_lock(&slab_mutex); 1034 return seq_list_start(&slab_caches, *pos); 1035 } 1036 1037 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1038 { 1039 return seq_list_next(p, &slab_caches, pos); 1040 } 1041 1042 static void slab_stop(struct seq_file *m, void *p) 1043 { 1044 mutex_unlock(&slab_mutex); 1045 } 1046 1047 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1048 { 1049 struct slabinfo sinfo; 1050 1051 memset(&sinfo, 0, sizeof(sinfo)); 1052 get_slabinfo(s, &sinfo); 1053 1054 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1055 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1056 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1057 1058 seq_printf(m, " : tunables %4u %4u %4u", 1059 sinfo.limit, sinfo.batchcount, sinfo.shared); 1060 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1061 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1062 slabinfo_show_stats(m, s); 1063 seq_putc(m, '\n'); 1064 } 1065 1066 static int slab_show(struct seq_file *m, void *p) 1067 { 1068 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1069 1070 if (p == slab_caches.next) 1071 print_slabinfo_header(m); 1072 cache_show(s, m); 1073 return 0; 1074 } 1075 1076 void dump_unreclaimable_slab(void) 1077 { 1078 struct kmem_cache *s; 1079 struct slabinfo sinfo; 1080 1081 /* 1082 * Here acquiring slab_mutex is risky since we don't prefer to get 1083 * sleep in oom path. But, without mutex hold, it may introduce a 1084 * risk of crash. 1085 * Use mutex_trylock to protect the list traverse, dump nothing 1086 * without acquiring the mutex. 1087 */ 1088 if (!mutex_trylock(&slab_mutex)) { 1089 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1090 return; 1091 } 1092 1093 pr_info("Unreclaimable slab info:\n"); 1094 pr_info("Name Used Total\n"); 1095 1096 list_for_each_entry(s, &slab_caches, list) { 1097 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1098 continue; 1099 1100 get_slabinfo(s, &sinfo); 1101 1102 if (sinfo.num_objs > 0) 1103 pr_info("%-17s %10luKB %10luKB\n", s->name, 1104 (sinfo.active_objs * s->size) / 1024, 1105 (sinfo.num_objs * s->size) / 1024); 1106 } 1107 mutex_unlock(&slab_mutex); 1108 } 1109 1110 /* 1111 * slabinfo_op - iterator that generates /proc/slabinfo 1112 * 1113 * Output layout: 1114 * cache-name 1115 * num-active-objs 1116 * total-objs 1117 * object size 1118 * num-active-slabs 1119 * total-slabs 1120 * num-pages-per-slab 1121 * + further values on SMP and with statistics enabled 1122 */ 1123 static const struct seq_operations slabinfo_op = { 1124 .start = slab_start, 1125 .next = slab_next, 1126 .stop = slab_stop, 1127 .show = slab_show, 1128 }; 1129 1130 static int slabinfo_open(struct inode *inode, struct file *file) 1131 { 1132 return seq_open(file, &slabinfo_op); 1133 } 1134 1135 static const struct proc_ops slabinfo_proc_ops = { 1136 .proc_flags = PROC_ENTRY_PERMANENT, 1137 .proc_open = slabinfo_open, 1138 .proc_read = seq_read, 1139 .proc_write = slabinfo_write, 1140 .proc_lseek = seq_lseek, 1141 .proc_release = seq_release, 1142 }; 1143 1144 static int __init slab_proc_init(void) 1145 { 1146 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1147 return 0; 1148 } 1149 module_init(slab_proc_init); 1150 1151 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1152 1153 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1154 gfp_t flags) 1155 { 1156 void *ret; 1157 size_t ks; 1158 1159 /* Don't use instrumented ksize to allow precise KASAN poisoning. */ 1160 if (likely(!ZERO_OR_NULL_PTR(p))) { 1161 if (!kasan_check_byte(p)) 1162 return NULL; 1163 ks = kfence_ksize(p) ?: __ksize(p); 1164 } else 1165 ks = 0; 1166 1167 /* If the object still fits, repoison it precisely. */ 1168 if (ks >= new_size) { 1169 p = kasan_krealloc((void *)p, new_size, flags); 1170 return (void *)p; 1171 } 1172 1173 ret = kmalloc_track_caller(new_size, flags); 1174 if (ret && p) { 1175 /* Disable KASAN checks as the object's redzone is accessed. */ 1176 kasan_disable_current(); 1177 memcpy(ret, kasan_reset_tag(p), ks); 1178 kasan_enable_current(); 1179 } 1180 1181 return ret; 1182 } 1183 1184 /** 1185 * krealloc - reallocate memory. The contents will remain unchanged. 1186 * @p: object to reallocate memory for. 1187 * @new_size: how many bytes of memory are required. 1188 * @flags: the type of memory to allocate. 1189 * 1190 * The contents of the object pointed to are preserved up to the 1191 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1192 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1193 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1194 * 1195 * Return: pointer to the allocated memory or %NULL in case of error 1196 */ 1197 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1198 { 1199 void *ret; 1200 1201 if (unlikely(!new_size)) { 1202 kfree(p); 1203 return ZERO_SIZE_PTR; 1204 } 1205 1206 ret = __do_krealloc(p, new_size, flags); 1207 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1208 kfree(p); 1209 1210 return ret; 1211 } 1212 EXPORT_SYMBOL(krealloc); 1213 1214 /** 1215 * kfree_sensitive - Clear sensitive information in memory before freeing 1216 * @p: object to free memory of 1217 * 1218 * The memory of the object @p points to is zeroed before freed. 1219 * If @p is %NULL, kfree_sensitive() does nothing. 1220 * 1221 * Note: this function zeroes the whole allocated buffer which can be a good 1222 * deal bigger than the requested buffer size passed to kmalloc(). So be 1223 * careful when using this function in performance sensitive code. 1224 */ 1225 void kfree_sensitive(const void *p) 1226 { 1227 size_t ks; 1228 void *mem = (void *)p; 1229 1230 ks = ksize(mem); 1231 if (ks) 1232 memzero_explicit(mem, ks); 1233 kfree(mem); 1234 } 1235 EXPORT_SYMBOL(kfree_sensitive); 1236 1237 /** 1238 * ksize - get the actual amount of memory allocated for a given object 1239 * @objp: Pointer to the object 1240 * 1241 * kmalloc may internally round up allocations and return more memory 1242 * than requested. ksize() can be used to determine the actual amount of 1243 * memory allocated. The caller may use this additional memory, even though 1244 * a smaller amount of memory was initially specified with the kmalloc call. 1245 * The caller must guarantee that objp points to a valid object previously 1246 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1247 * must not be freed during the duration of the call. 1248 * 1249 * Return: size of the actual memory used by @objp in bytes 1250 */ 1251 size_t ksize(const void *objp) 1252 { 1253 size_t size; 1254 1255 /* 1256 * We need to first check that the pointer to the object is valid, and 1257 * only then unpoison the memory. The report printed from ksize() is 1258 * more useful, then when it's printed later when the behaviour could 1259 * be undefined due to a potential use-after-free or double-free. 1260 * 1261 * We use kasan_check_byte(), which is supported for the hardware 1262 * tag-based KASAN mode, unlike kasan_check_read/write(). 1263 * 1264 * If the pointed to memory is invalid, we return 0 to avoid users of 1265 * ksize() writing to and potentially corrupting the memory region. 1266 * 1267 * We want to perform the check before __ksize(), to avoid potentially 1268 * crashing in __ksize() due to accessing invalid metadata. 1269 */ 1270 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1271 return 0; 1272 1273 size = kfence_ksize(objp) ?: __ksize(objp); 1274 /* 1275 * We assume that ksize callers could use whole allocated area, 1276 * so we need to unpoison this area. 1277 */ 1278 kasan_unpoison_range(objp, size); 1279 return size; 1280 } 1281 EXPORT_SYMBOL(ksize); 1282 1283 /* Tracepoints definitions. */ 1284 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1285 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1286 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1287 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1288 EXPORT_TRACEPOINT_SYMBOL(kfree); 1289 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1290 1291 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1292 { 1293 if (__should_failslab(s, gfpflags)) 1294 return -ENOMEM; 1295 return 0; 1296 } 1297 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1298