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 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 396 { 397 LIST_HEAD(to_destroy); 398 struct kmem_cache *s, *s2; 399 400 /* 401 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 402 * @slab_caches_to_rcu_destroy list. The slab pages are freed 403 * through RCU and the associated kmem_cache are dereferenced 404 * while freeing the pages, so the kmem_caches should be freed only 405 * after the pending RCU operations are finished. As rcu_barrier() 406 * is a pretty slow operation, we batch all pending destructions 407 * asynchronously. 408 */ 409 mutex_lock(&slab_mutex); 410 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 411 mutex_unlock(&slab_mutex); 412 413 if (list_empty(&to_destroy)) 414 return; 415 416 rcu_barrier(); 417 418 list_for_each_entry_safe(s, s2, &to_destroy, list) { 419 debugfs_slab_release(s); 420 kfence_shutdown_cache(s); 421 #ifdef SLAB_SUPPORTS_SYSFS 422 sysfs_slab_release(s); 423 #else 424 slab_kmem_cache_release(s); 425 #endif 426 } 427 } 428 429 static int shutdown_cache(struct kmem_cache *s) 430 { 431 /* free asan quarantined objects */ 432 kasan_cache_shutdown(s); 433 434 if (__kmem_cache_shutdown(s) != 0) 435 return -EBUSY; 436 437 list_del(&s->list); 438 439 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 440 #ifdef SLAB_SUPPORTS_SYSFS 441 sysfs_slab_unlink(s); 442 #endif 443 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 444 schedule_work(&slab_caches_to_rcu_destroy_work); 445 } else { 446 kfence_shutdown_cache(s); 447 debugfs_slab_release(s); 448 #ifdef SLAB_SUPPORTS_SYSFS 449 sysfs_slab_unlink(s); 450 sysfs_slab_release(s); 451 #else 452 slab_kmem_cache_release(s); 453 #endif 454 } 455 456 return 0; 457 } 458 459 void slab_kmem_cache_release(struct kmem_cache *s) 460 { 461 __kmem_cache_release(s); 462 kfree_const(s->name); 463 kmem_cache_free(kmem_cache, s); 464 } 465 466 void kmem_cache_destroy(struct kmem_cache *s) 467 { 468 if (unlikely(!s) || !kasan_check_byte(s)) 469 return; 470 471 cpus_read_lock(); 472 mutex_lock(&slab_mutex); 473 474 s->refcount--; 475 if (s->refcount) 476 goto out_unlock; 477 478 WARN(shutdown_cache(s), 479 "%s %s: Slab cache still has objects when called from %pS", 480 __func__, s->name, (void *)_RET_IP_); 481 out_unlock: 482 mutex_unlock(&slab_mutex); 483 cpus_read_unlock(); 484 } 485 EXPORT_SYMBOL(kmem_cache_destroy); 486 487 /** 488 * kmem_cache_shrink - Shrink a cache. 489 * @cachep: The cache to shrink. 490 * 491 * Releases as many slabs as possible for a cache. 492 * To help debugging, a zero exit status indicates all slabs were released. 493 * 494 * Return: %0 if all slabs were released, non-zero otherwise 495 */ 496 int kmem_cache_shrink(struct kmem_cache *cachep) 497 { 498 int ret; 499 500 501 kasan_cache_shrink(cachep); 502 ret = __kmem_cache_shrink(cachep); 503 504 return ret; 505 } 506 EXPORT_SYMBOL(kmem_cache_shrink); 507 508 bool slab_is_available(void) 509 { 510 return slab_state >= UP; 511 } 512 513 #ifdef CONFIG_PRINTK 514 /** 515 * kmem_valid_obj - does the pointer reference a valid slab object? 516 * @object: pointer to query. 517 * 518 * Return: %true if the pointer is to a not-yet-freed object from 519 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 520 * is to an already-freed object, and %false otherwise. 521 */ 522 bool kmem_valid_obj(void *object) 523 { 524 struct folio *folio; 525 526 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 527 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 528 return false; 529 folio = virt_to_folio(object); 530 return folio_test_slab(folio); 531 } 532 EXPORT_SYMBOL_GPL(kmem_valid_obj); 533 534 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 535 { 536 if (__kfence_obj_info(kpp, object, slab)) 537 return; 538 __kmem_obj_info(kpp, object, slab); 539 } 540 541 /** 542 * kmem_dump_obj - Print available slab provenance information 543 * @object: slab object for which to find provenance information. 544 * 545 * This function uses pr_cont(), so that the caller is expected to have 546 * printed out whatever preamble is appropriate. The provenance information 547 * depends on the type of object and on how much debugging is enabled. 548 * For a slab-cache object, the fact that it is a slab object is printed, 549 * and, if available, the slab name, return address, and stack trace from 550 * the allocation and last free path of that object. 551 * 552 * This function will splat if passed a pointer to a non-slab object. 553 * If you are not sure what type of object you have, you should instead 554 * use mem_dump_obj(). 555 */ 556 void kmem_dump_obj(void *object) 557 { 558 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 559 int i; 560 struct slab *slab; 561 unsigned long ptroffset; 562 struct kmem_obj_info kp = { }; 563 564 if (WARN_ON_ONCE(!virt_addr_valid(object))) 565 return; 566 slab = virt_to_slab(object); 567 if (WARN_ON_ONCE(!slab)) { 568 pr_cont(" non-slab memory.\n"); 569 return; 570 } 571 kmem_obj_info(&kp, object, slab); 572 if (kp.kp_slab_cache) 573 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 574 else 575 pr_cont(" slab%s", cp); 576 if (is_kfence_address(object)) 577 pr_cont(" (kfence)"); 578 if (kp.kp_objp) 579 pr_cont(" start %px", kp.kp_objp); 580 if (kp.kp_data_offset) 581 pr_cont(" data offset %lu", kp.kp_data_offset); 582 if (kp.kp_objp) { 583 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 584 pr_cont(" pointer offset %lu", ptroffset); 585 } 586 if (kp.kp_slab_cache && kp.kp_slab_cache->usersize) 587 pr_cont(" size %u", kp.kp_slab_cache->usersize); 588 if (kp.kp_ret) 589 pr_cont(" allocated at %pS\n", kp.kp_ret); 590 else 591 pr_cont("\n"); 592 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 593 if (!kp.kp_stack[i]) 594 break; 595 pr_info(" %pS\n", kp.kp_stack[i]); 596 } 597 598 if (kp.kp_free_stack[0]) 599 pr_cont(" Free path:\n"); 600 601 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 602 if (!kp.kp_free_stack[i]) 603 break; 604 pr_info(" %pS\n", kp.kp_free_stack[i]); 605 } 606 607 } 608 EXPORT_SYMBOL_GPL(kmem_dump_obj); 609 #endif 610 611 #ifndef CONFIG_SLOB 612 /* Create a cache during boot when no slab services are available yet */ 613 void __init create_boot_cache(struct kmem_cache *s, const char *name, 614 unsigned int size, slab_flags_t flags, 615 unsigned int useroffset, unsigned int usersize) 616 { 617 int err; 618 unsigned int align = ARCH_KMALLOC_MINALIGN; 619 620 s->name = name; 621 s->size = s->object_size = size; 622 623 /* 624 * For power of two sizes, guarantee natural alignment for kmalloc 625 * caches, regardless of SL*B debugging options. 626 */ 627 if (is_power_of_2(size)) 628 align = max(align, size); 629 s->align = calculate_alignment(flags, align, size); 630 631 s->useroffset = useroffset; 632 s->usersize = usersize; 633 634 err = __kmem_cache_create(s, flags); 635 636 if (err) 637 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 638 name, size, err); 639 640 s->refcount = -1; /* Exempt from merging for now */ 641 } 642 643 struct kmem_cache *__init create_kmalloc_cache(const char *name, 644 unsigned int size, slab_flags_t flags, 645 unsigned int useroffset, unsigned int usersize) 646 { 647 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 648 649 if (!s) 650 panic("Out of memory when creating slab %s\n", name); 651 652 create_boot_cache(s, name, size, flags, useroffset, usersize); 653 kasan_cache_create_kmalloc(s); 654 list_add(&s->list, &slab_caches); 655 s->refcount = 1; 656 return s; 657 } 658 659 struct kmem_cache * 660 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 661 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 662 EXPORT_SYMBOL(kmalloc_caches); 663 664 /* 665 * Conversion table for small slabs sizes / 8 to the index in the 666 * kmalloc array. This is necessary for slabs < 192 since we have non power 667 * of two cache sizes there. The size of larger slabs can be determined using 668 * fls. 669 */ 670 static u8 size_index[24] __ro_after_init = { 671 3, /* 8 */ 672 4, /* 16 */ 673 5, /* 24 */ 674 5, /* 32 */ 675 6, /* 40 */ 676 6, /* 48 */ 677 6, /* 56 */ 678 6, /* 64 */ 679 1, /* 72 */ 680 1, /* 80 */ 681 1, /* 88 */ 682 1, /* 96 */ 683 7, /* 104 */ 684 7, /* 112 */ 685 7, /* 120 */ 686 7, /* 128 */ 687 2, /* 136 */ 688 2, /* 144 */ 689 2, /* 152 */ 690 2, /* 160 */ 691 2, /* 168 */ 692 2, /* 176 */ 693 2, /* 184 */ 694 2 /* 192 */ 695 }; 696 697 static inline unsigned int size_index_elem(unsigned int bytes) 698 { 699 return (bytes - 1) / 8; 700 } 701 702 /* 703 * Find the kmem_cache structure that serves a given size of 704 * allocation 705 */ 706 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 707 { 708 unsigned int index; 709 710 if (size <= 192) { 711 if (!size) 712 return ZERO_SIZE_PTR; 713 714 index = size_index[size_index_elem(size)]; 715 } else { 716 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 717 return NULL; 718 index = fls(size - 1); 719 } 720 721 return kmalloc_caches[kmalloc_type(flags)][index]; 722 } 723 724 #ifdef CONFIG_ZONE_DMA 725 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 726 #else 727 #define KMALLOC_DMA_NAME(sz) 728 #endif 729 730 #ifdef CONFIG_MEMCG_KMEM 731 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 732 #else 733 #define KMALLOC_CGROUP_NAME(sz) 734 #endif 735 736 #define INIT_KMALLOC_INFO(__size, __short_size) \ 737 { \ 738 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 739 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 740 KMALLOC_CGROUP_NAME(__short_size) \ 741 KMALLOC_DMA_NAME(__short_size) \ 742 .size = __size, \ 743 } 744 745 /* 746 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 747 * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is 748 * kmalloc-32M. 749 */ 750 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 751 INIT_KMALLOC_INFO(0, 0), 752 INIT_KMALLOC_INFO(96, 96), 753 INIT_KMALLOC_INFO(192, 192), 754 INIT_KMALLOC_INFO(8, 8), 755 INIT_KMALLOC_INFO(16, 16), 756 INIT_KMALLOC_INFO(32, 32), 757 INIT_KMALLOC_INFO(64, 64), 758 INIT_KMALLOC_INFO(128, 128), 759 INIT_KMALLOC_INFO(256, 256), 760 INIT_KMALLOC_INFO(512, 512), 761 INIT_KMALLOC_INFO(1024, 1k), 762 INIT_KMALLOC_INFO(2048, 2k), 763 INIT_KMALLOC_INFO(4096, 4k), 764 INIT_KMALLOC_INFO(8192, 8k), 765 INIT_KMALLOC_INFO(16384, 16k), 766 INIT_KMALLOC_INFO(32768, 32k), 767 INIT_KMALLOC_INFO(65536, 64k), 768 INIT_KMALLOC_INFO(131072, 128k), 769 INIT_KMALLOC_INFO(262144, 256k), 770 INIT_KMALLOC_INFO(524288, 512k), 771 INIT_KMALLOC_INFO(1048576, 1M), 772 INIT_KMALLOC_INFO(2097152, 2M), 773 INIT_KMALLOC_INFO(4194304, 4M), 774 INIT_KMALLOC_INFO(8388608, 8M), 775 INIT_KMALLOC_INFO(16777216, 16M), 776 INIT_KMALLOC_INFO(33554432, 32M) 777 }; 778 779 /* 780 * Patch up the size_index table if we have strange large alignment 781 * requirements for the kmalloc array. This is only the case for 782 * MIPS it seems. The standard arches will not generate any code here. 783 * 784 * Largest permitted alignment is 256 bytes due to the way we 785 * handle the index determination for the smaller caches. 786 * 787 * Make sure that nothing crazy happens if someone starts tinkering 788 * around with ARCH_KMALLOC_MINALIGN 789 */ 790 void __init setup_kmalloc_cache_index_table(void) 791 { 792 unsigned int i; 793 794 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 795 !is_power_of_2(KMALLOC_MIN_SIZE)); 796 797 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 798 unsigned int elem = size_index_elem(i); 799 800 if (elem >= ARRAY_SIZE(size_index)) 801 break; 802 size_index[elem] = KMALLOC_SHIFT_LOW; 803 } 804 805 if (KMALLOC_MIN_SIZE >= 64) { 806 /* 807 * The 96 byte sized cache is not used if the alignment 808 * is 64 byte. 809 */ 810 for (i = 64 + 8; i <= 96; i += 8) 811 size_index[size_index_elem(i)] = 7; 812 813 } 814 815 if (KMALLOC_MIN_SIZE >= 128) { 816 /* 817 * The 192 byte sized cache is not used if the alignment 818 * is 128 byte. Redirect kmalloc to use the 256 byte cache 819 * instead. 820 */ 821 for (i = 128 + 8; i <= 192; i += 8) 822 size_index[size_index_elem(i)] = 8; 823 } 824 } 825 826 static void __init 827 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 828 { 829 if (type == KMALLOC_RECLAIM) { 830 flags |= SLAB_RECLAIM_ACCOUNT; 831 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) { 832 if (mem_cgroup_kmem_disabled()) { 833 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 834 return; 835 } 836 flags |= SLAB_ACCOUNT; 837 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 838 flags |= SLAB_CACHE_DMA; 839 } 840 841 kmalloc_caches[type][idx] = create_kmalloc_cache( 842 kmalloc_info[idx].name[type], 843 kmalloc_info[idx].size, flags, 0, 844 kmalloc_info[idx].size); 845 846 /* 847 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for 848 * KMALLOC_NORMAL caches. 849 */ 850 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL)) 851 kmalloc_caches[type][idx]->refcount = -1; 852 } 853 854 /* 855 * Create the kmalloc array. Some of the regular kmalloc arrays 856 * may already have been created because they were needed to 857 * enable allocations for slab creation. 858 */ 859 void __init create_kmalloc_caches(slab_flags_t flags) 860 { 861 int i; 862 enum kmalloc_cache_type type; 863 864 /* 865 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined 866 */ 867 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 868 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 869 if (!kmalloc_caches[type][i]) 870 new_kmalloc_cache(i, type, flags); 871 872 /* 873 * Caches that are not of the two-to-the-power-of size. 874 * These have to be created immediately after the 875 * earlier power of two caches 876 */ 877 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 878 !kmalloc_caches[type][1]) 879 new_kmalloc_cache(1, type, flags); 880 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 881 !kmalloc_caches[type][2]) 882 new_kmalloc_cache(2, type, flags); 883 } 884 } 885 886 /* Kmalloc array is now usable */ 887 slab_state = UP; 888 } 889 #endif /* !CONFIG_SLOB */ 890 891 gfp_t kmalloc_fix_flags(gfp_t flags) 892 { 893 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 894 895 flags &= ~GFP_SLAB_BUG_MASK; 896 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 897 invalid_mask, &invalid_mask, flags, &flags); 898 dump_stack(); 899 900 return flags; 901 } 902 903 /* 904 * To avoid unnecessary overhead, we pass through large allocation requests 905 * directly to the page allocator. We use __GFP_COMP, because we will need to 906 * know the allocation order to free the pages properly in kfree. 907 */ 908 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 909 { 910 void *ret = NULL; 911 struct page *page; 912 913 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 914 flags = kmalloc_fix_flags(flags); 915 916 flags |= __GFP_COMP; 917 page = alloc_pages(flags, order); 918 if (likely(page)) { 919 ret = page_address(page); 920 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 921 PAGE_SIZE << order); 922 } 923 ret = kasan_kmalloc_large(ret, size, flags); 924 /* As ret might get tagged, call kmemleak hook after KASAN. */ 925 kmemleak_alloc(ret, size, 1, flags); 926 return ret; 927 } 928 EXPORT_SYMBOL(kmalloc_order); 929 930 #ifdef CONFIG_TRACING 931 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 932 { 933 void *ret = kmalloc_order(size, flags, order); 934 trace_kmalloc(_RET_IP_, ret, NULL, size, PAGE_SIZE << order, flags); 935 return ret; 936 } 937 EXPORT_SYMBOL(kmalloc_order_trace); 938 #endif 939 940 #ifdef CONFIG_SLAB_FREELIST_RANDOM 941 /* Randomize a generic freelist */ 942 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 943 unsigned int count) 944 { 945 unsigned int rand; 946 unsigned int i; 947 948 for (i = 0; i < count; i++) 949 list[i] = i; 950 951 /* Fisher-Yates shuffle */ 952 for (i = count - 1; i > 0; i--) { 953 rand = prandom_u32_state(state); 954 rand %= (i + 1); 955 swap(list[i], list[rand]); 956 } 957 } 958 959 /* Create a random sequence per cache */ 960 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 961 gfp_t gfp) 962 { 963 struct rnd_state state; 964 965 if (count < 2 || cachep->random_seq) 966 return 0; 967 968 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 969 if (!cachep->random_seq) 970 return -ENOMEM; 971 972 /* Get best entropy at this stage of boot */ 973 prandom_seed_state(&state, get_random_long()); 974 975 freelist_randomize(&state, cachep->random_seq, count); 976 return 0; 977 } 978 979 /* Destroy the per-cache random freelist sequence */ 980 void cache_random_seq_destroy(struct kmem_cache *cachep) 981 { 982 kfree(cachep->random_seq); 983 cachep->random_seq = NULL; 984 } 985 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 986 987 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 988 #ifdef CONFIG_SLAB 989 #define SLABINFO_RIGHTS (0600) 990 #else 991 #define SLABINFO_RIGHTS (0400) 992 #endif 993 994 static void print_slabinfo_header(struct seq_file *m) 995 { 996 /* 997 * Output format version, so at least we can change it 998 * without _too_ many complaints. 999 */ 1000 #ifdef CONFIG_DEBUG_SLAB 1001 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1002 #else 1003 seq_puts(m, "slabinfo - version: 2.1\n"); 1004 #endif 1005 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1006 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1007 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1008 #ifdef CONFIG_DEBUG_SLAB 1009 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1010 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1011 #endif 1012 seq_putc(m, '\n'); 1013 } 1014 1015 static void *slab_start(struct seq_file *m, loff_t *pos) 1016 { 1017 mutex_lock(&slab_mutex); 1018 return seq_list_start(&slab_caches, *pos); 1019 } 1020 1021 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1022 { 1023 return seq_list_next(p, &slab_caches, pos); 1024 } 1025 1026 static void slab_stop(struct seq_file *m, void *p) 1027 { 1028 mutex_unlock(&slab_mutex); 1029 } 1030 1031 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1032 { 1033 struct slabinfo sinfo; 1034 1035 memset(&sinfo, 0, sizeof(sinfo)); 1036 get_slabinfo(s, &sinfo); 1037 1038 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1039 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1040 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1041 1042 seq_printf(m, " : tunables %4u %4u %4u", 1043 sinfo.limit, sinfo.batchcount, sinfo.shared); 1044 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1045 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1046 slabinfo_show_stats(m, s); 1047 seq_putc(m, '\n'); 1048 } 1049 1050 static int slab_show(struct seq_file *m, void *p) 1051 { 1052 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1053 1054 if (p == slab_caches.next) 1055 print_slabinfo_header(m); 1056 cache_show(s, m); 1057 return 0; 1058 } 1059 1060 void dump_unreclaimable_slab(void) 1061 { 1062 struct kmem_cache *s; 1063 struct slabinfo sinfo; 1064 1065 /* 1066 * Here acquiring slab_mutex is risky since we don't prefer to get 1067 * sleep in oom path. But, without mutex hold, it may introduce a 1068 * risk of crash. 1069 * Use mutex_trylock to protect the list traverse, dump nothing 1070 * without acquiring the mutex. 1071 */ 1072 if (!mutex_trylock(&slab_mutex)) { 1073 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1074 return; 1075 } 1076 1077 pr_info("Unreclaimable slab info:\n"); 1078 pr_info("Name Used Total\n"); 1079 1080 list_for_each_entry(s, &slab_caches, list) { 1081 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1082 continue; 1083 1084 get_slabinfo(s, &sinfo); 1085 1086 if (sinfo.num_objs > 0) 1087 pr_info("%-17s %10luKB %10luKB\n", s->name, 1088 (sinfo.active_objs * s->size) / 1024, 1089 (sinfo.num_objs * s->size) / 1024); 1090 } 1091 mutex_unlock(&slab_mutex); 1092 } 1093 1094 /* 1095 * slabinfo_op - iterator that generates /proc/slabinfo 1096 * 1097 * Output layout: 1098 * cache-name 1099 * num-active-objs 1100 * total-objs 1101 * object size 1102 * num-active-slabs 1103 * total-slabs 1104 * num-pages-per-slab 1105 * + further values on SMP and with statistics enabled 1106 */ 1107 static const struct seq_operations slabinfo_op = { 1108 .start = slab_start, 1109 .next = slab_next, 1110 .stop = slab_stop, 1111 .show = slab_show, 1112 }; 1113 1114 static int slabinfo_open(struct inode *inode, struct file *file) 1115 { 1116 return seq_open(file, &slabinfo_op); 1117 } 1118 1119 static const struct proc_ops slabinfo_proc_ops = { 1120 .proc_flags = PROC_ENTRY_PERMANENT, 1121 .proc_open = slabinfo_open, 1122 .proc_read = seq_read, 1123 .proc_write = slabinfo_write, 1124 .proc_lseek = seq_lseek, 1125 .proc_release = seq_release, 1126 }; 1127 1128 static int __init slab_proc_init(void) 1129 { 1130 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1131 return 0; 1132 } 1133 module_init(slab_proc_init); 1134 1135 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1136 1137 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1138 gfp_t flags) 1139 { 1140 void *ret; 1141 size_t ks; 1142 1143 /* Don't use instrumented ksize to allow precise KASAN poisoning. */ 1144 if (likely(!ZERO_OR_NULL_PTR(p))) { 1145 if (!kasan_check_byte(p)) 1146 return NULL; 1147 ks = kfence_ksize(p) ?: __ksize(p); 1148 } else 1149 ks = 0; 1150 1151 /* If the object still fits, repoison it precisely. */ 1152 if (ks >= new_size) { 1153 p = kasan_krealloc((void *)p, new_size, flags); 1154 return (void *)p; 1155 } 1156 1157 ret = kmalloc_track_caller(new_size, flags); 1158 if (ret && p) { 1159 /* Disable KASAN checks as the object's redzone is accessed. */ 1160 kasan_disable_current(); 1161 memcpy(ret, kasan_reset_tag(p), ks); 1162 kasan_enable_current(); 1163 } 1164 1165 return ret; 1166 } 1167 1168 /** 1169 * krealloc - reallocate memory. The contents will remain unchanged. 1170 * @p: object to reallocate memory for. 1171 * @new_size: how many bytes of memory are required. 1172 * @flags: the type of memory to allocate. 1173 * 1174 * The contents of the object pointed to are preserved up to the 1175 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1176 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1177 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1178 * 1179 * Return: pointer to the allocated memory or %NULL in case of error 1180 */ 1181 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1182 { 1183 void *ret; 1184 1185 if (unlikely(!new_size)) { 1186 kfree(p); 1187 return ZERO_SIZE_PTR; 1188 } 1189 1190 ret = __do_krealloc(p, new_size, flags); 1191 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1192 kfree(p); 1193 1194 return ret; 1195 } 1196 EXPORT_SYMBOL(krealloc); 1197 1198 /** 1199 * kfree_sensitive - Clear sensitive information in memory before freeing 1200 * @p: object to free memory of 1201 * 1202 * The memory of the object @p points to is zeroed before freed. 1203 * If @p is %NULL, kfree_sensitive() does nothing. 1204 * 1205 * Note: this function zeroes the whole allocated buffer which can be a good 1206 * deal bigger than the requested buffer size passed to kmalloc(). So be 1207 * careful when using this function in performance sensitive code. 1208 */ 1209 void kfree_sensitive(const void *p) 1210 { 1211 size_t ks; 1212 void *mem = (void *)p; 1213 1214 ks = ksize(mem); 1215 if (ks) 1216 memzero_explicit(mem, ks); 1217 kfree(mem); 1218 } 1219 EXPORT_SYMBOL(kfree_sensitive); 1220 1221 /** 1222 * ksize - get the actual amount of memory allocated for a given object 1223 * @objp: Pointer to the object 1224 * 1225 * kmalloc may internally round up allocations and return more memory 1226 * than requested. ksize() can be used to determine the actual amount of 1227 * memory allocated. The caller may use this additional memory, even though 1228 * a smaller amount of memory was initially specified with the kmalloc call. 1229 * The caller must guarantee that objp points to a valid object previously 1230 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1231 * must not be freed during the duration of the call. 1232 * 1233 * Return: size of the actual memory used by @objp in bytes 1234 */ 1235 size_t ksize(const void *objp) 1236 { 1237 size_t size; 1238 1239 /* 1240 * We need to first check that the pointer to the object is valid, and 1241 * only then unpoison the memory. The report printed from ksize() is 1242 * more useful, then when it's printed later when the behaviour could 1243 * be undefined due to a potential use-after-free or double-free. 1244 * 1245 * We use kasan_check_byte(), which is supported for the hardware 1246 * tag-based KASAN mode, unlike kasan_check_read/write(). 1247 * 1248 * If the pointed to memory is invalid, we return 0 to avoid users of 1249 * ksize() writing to and potentially corrupting the memory region. 1250 * 1251 * We want to perform the check before __ksize(), to avoid potentially 1252 * crashing in __ksize() due to accessing invalid metadata. 1253 */ 1254 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1255 return 0; 1256 1257 size = kfence_ksize(objp) ?: __ksize(objp); 1258 /* 1259 * We assume that ksize callers could use whole allocated area, 1260 * so we need to unpoison this area. 1261 */ 1262 kasan_unpoison_range(objp, size); 1263 return size; 1264 } 1265 EXPORT_SYMBOL(ksize); 1266 1267 /* Tracepoints definitions. */ 1268 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1269 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1270 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1271 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1272 EXPORT_TRACEPOINT_SYMBOL(kfree); 1273 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1274 1275 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1276 { 1277 if (__should_failslab(s, gfpflags)) 1278 return -ENOMEM; 1279 return 0; 1280 } 1281 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1282