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 28 #define CREATE_TRACE_POINTS 29 #include <trace/events/kmem.h> 30 31 #include "internal.h" 32 33 #include "slab.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 #ifdef CONFIG_HARDENED_USERCOPY 41 bool usercopy_fallback __ro_after_init = 42 IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK); 43 module_param(usercopy_fallback, bool, 0400); 44 MODULE_PARM_DESC(usercopy_fallback, 45 "WARN instead of reject usercopy whitelist violations"); 46 #endif 47 48 static LIST_HEAD(slab_caches_to_rcu_destroy); 49 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 50 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 51 slab_caches_to_rcu_destroy_workfn); 52 53 /* 54 * Set of flags that will prevent slab merging 55 */ 56 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 57 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 58 SLAB_FAILSLAB | kasan_never_merge()) 59 60 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 61 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 62 63 /* 64 * Merge control. If this is set then no merging of slab caches will occur. 65 */ 66 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 67 68 static int __init setup_slab_nomerge(char *str) 69 { 70 slab_nomerge = true; 71 return 1; 72 } 73 74 static int __init setup_slab_merge(char *str) 75 { 76 slab_nomerge = false; 77 return 1; 78 } 79 80 #ifdef CONFIG_SLUB 81 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 82 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0); 83 #endif 84 85 __setup("slab_nomerge", setup_slab_nomerge); 86 __setup("slab_merge", setup_slab_merge); 87 88 /* 89 * Determine the size of a slab object 90 */ 91 unsigned int kmem_cache_size(struct kmem_cache *s) 92 { 93 return s->object_size; 94 } 95 EXPORT_SYMBOL(kmem_cache_size); 96 97 #ifdef CONFIG_DEBUG_VM 98 static int kmem_cache_sanity_check(const char *name, unsigned int size) 99 { 100 if (!name || in_interrupt() || size < sizeof(void *) || 101 size > KMALLOC_MAX_SIZE) { 102 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 103 return -EINVAL; 104 } 105 106 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 107 return 0; 108 } 109 #else 110 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 111 { 112 return 0; 113 } 114 #endif 115 116 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) 117 { 118 size_t i; 119 120 for (i = 0; i < nr; i++) { 121 if (s) 122 kmem_cache_free(s, p[i]); 123 else 124 kfree(p[i]); 125 } 126 } 127 128 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, 129 void **p) 130 { 131 size_t i; 132 133 for (i = 0; i < nr; i++) { 134 void *x = p[i] = kmem_cache_alloc(s, flags); 135 if (!x) { 136 __kmem_cache_free_bulk(s, i, p); 137 return 0; 138 } 139 } 140 return i; 141 } 142 143 /* 144 * Figure out what the alignment of the objects will be given a set of 145 * flags, a user specified alignment and the size of the objects. 146 */ 147 static unsigned int calculate_alignment(slab_flags_t flags, 148 unsigned int align, unsigned int size) 149 { 150 /* 151 * If the user wants hardware cache aligned objects then follow that 152 * suggestion if the object is sufficiently large. 153 * 154 * The hardware cache alignment cannot override the specified 155 * alignment though. If that is greater then use it. 156 */ 157 if (flags & SLAB_HWCACHE_ALIGN) { 158 unsigned int ralign; 159 160 ralign = cache_line_size(); 161 while (size <= ralign / 2) 162 ralign /= 2; 163 align = max(align, ralign); 164 } 165 166 if (align < ARCH_SLAB_MINALIGN) 167 align = ARCH_SLAB_MINALIGN; 168 169 return ALIGN(align, sizeof(void *)); 170 } 171 172 /* 173 * Find a mergeable slab cache 174 */ 175 int slab_unmergeable(struct kmem_cache *s) 176 { 177 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 178 return 1; 179 180 if (s->ctor) 181 return 1; 182 183 if (s->usersize) 184 return 1; 185 186 /* 187 * We may have set a slab to be unmergeable during bootstrap. 188 */ 189 if (s->refcount < 0) 190 return 1; 191 192 return 0; 193 } 194 195 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 196 slab_flags_t flags, const char *name, void (*ctor)(void *)) 197 { 198 struct kmem_cache *s; 199 200 if (slab_nomerge) 201 return NULL; 202 203 if (ctor) 204 return NULL; 205 206 size = ALIGN(size, sizeof(void *)); 207 align = calculate_alignment(flags, align, size); 208 size = ALIGN(size, align); 209 flags = kmem_cache_flags(size, flags, name); 210 211 if (flags & SLAB_NEVER_MERGE) 212 return NULL; 213 214 list_for_each_entry_reverse(s, &slab_caches, list) { 215 if (slab_unmergeable(s)) 216 continue; 217 218 if (size > s->size) 219 continue; 220 221 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 222 continue; 223 /* 224 * Check if alignment is compatible. 225 * Courtesy of Adrian Drzewiecki 226 */ 227 if ((s->size & ~(align - 1)) != s->size) 228 continue; 229 230 if (s->size - size >= sizeof(void *)) 231 continue; 232 233 if (IS_ENABLED(CONFIG_SLAB) && align && 234 (align > s->align || s->align % align)) 235 continue; 236 237 return s; 238 } 239 return NULL; 240 } 241 242 static struct kmem_cache *create_cache(const char *name, 243 unsigned int object_size, unsigned int align, 244 slab_flags_t flags, unsigned int useroffset, 245 unsigned int usersize, void (*ctor)(void *), 246 struct kmem_cache *root_cache) 247 { 248 struct kmem_cache *s; 249 int err; 250 251 if (WARN_ON(useroffset + usersize > object_size)) 252 useroffset = usersize = 0; 253 254 err = -ENOMEM; 255 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 256 if (!s) 257 goto out; 258 259 s->name = name; 260 s->size = s->object_size = object_size; 261 s->align = align; 262 s->ctor = ctor; 263 s->useroffset = useroffset; 264 s->usersize = usersize; 265 266 err = __kmem_cache_create(s, flags); 267 if (err) 268 goto out_free_cache; 269 270 s->refcount = 1; 271 list_add(&s->list, &slab_caches); 272 out: 273 if (err) 274 return ERR_PTR(err); 275 return s; 276 277 out_free_cache: 278 kmem_cache_free(kmem_cache, s); 279 goto out; 280 } 281 282 /** 283 * kmem_cache_create_usercopy - Create a cache with a region suitable 284 * for copying to userspace 285 * @name: A string which is used in /proc/slabinfo to identify this cache. 286 * @size: The size of objects to be created in this cache. 287 * @align: The required alignment for the objects. 288 * @flags: SLAB flags 289 * @useroffset: Usercopy region offset 290 * @usersize: Usercopy region size 291 * @ctor: A constructor for the objects. 292 * 293 * Cannot be called within a interrupt, but can be interrupted. 294 * The @ctor is run when new pages are allocated by the cache. 295 * 296 * The flags are 297 * 298 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 299 * to catch references to uninitialised memory. 300 * 301 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 302 * for buffer overruns. 303 * 304 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 305 * cacheline. This can be beneficial if you're counting cycles as closely 306 * as davem. 307 * 308 * Return: a pointer to the cache on success, NULL on failure. 309 */ 310 struct kmem_cache * 311 kmem_cache_create_usercopy(const char *name, 312 unsigned int size, unsigned int align, 313 slab_flags_t flags, 314 unsigned int useroffset, unsigned int usersize, 315 void (*ctor)(void *)) 316 { 317 struct kmem_cache *s = NULL; 318 const char *cache_name; 319 int err; 320 321 #ifdef CONFIG_SLUB_DEBUG 322 /* 323 * If no slub_debug was enabled globally, the static key is not yet 324 * enabled by setup_slub_debug(). Enable it if the cache is being 325 * created with any of the debugging flags passed explicitly. 326 */ 327 if (flags & SLAB_DEBUG_FLAGS) 328 static_branch_enable(&slub_debug_enabled); 329 #endif 330 331 mutex_lock(&slab_mutex); 332 333 err = kmem_cache_sanity_check(name, size); 334 if (err) { 335 goto out_unlock; 336 } 337 338 /* Refuse requests with allocator specific flags */ 339 if (flags & ~SLAB_FLAGS_PERMITTED) { 340 err = -EINVAL; 341 goto out_unlock; 342 } 343 344 /* 345 * Some allocators will constraint the set of valid flags to a subset 346 * of all flags. We expect them to define CACHE_CREATE_MASK in this 347 * case, and we'll just provide them with a sanitized version of the 348 * passed flags. 349 */ 350 flags &= CACHE_CREATE_MASK; 351 352 /* Fail closed on bad usersize of useroffset values. */ 353 if (WARN_ON(!usersize && useroffset) || 354 WARN_ON(size < usersize || size - usersize < useroffset)) 355 usersize = useroffset = 0; 356 357 if (!usersize) 358 s = __kmem_cache_alias(name, size, align, flags, ctor); 359 if (s) 360 goto out_unlock; 361 362 cache_name = kstrdup_const(name, GFP_KERNEL); 363 if (!cache_name) { 364 err = -ENOMEM; 365 goto out_unlock; 366 } 367 368 s = create_cache(cache_name, size, 369 calculate_alignment(flags, align, size), 370 flags, useroffset, usersize, ctor, NULL); 371 if (IS_ERR(s)) { 372 err = PTR_ERR(s); 373 kfree_const(cache_name); 374 } 375 376 out_unlock: 377 mutex_unlock(&slab_mutex); 378 379 if (err) { 380 if (flags & SLAB_PANIC) 381 panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n", 382 name, err); 383 else { 384 pr_warn("kmem_cache_create(%s) failed with error %d\n", 385 name, err); 386 dump_stack(); 387 } 388 return NULL; 389 } 390 return s; 391 } 392 EXPORT_SYMBOL(kmem_cache_create_usercopy); 393 394 /** 395 * kmem_cache_create - Create a cache. 396 * @name: A string which is used in /proc/slabinfo to identify this cache. 397 * @size: The size of objects to be created in this cache. 398 * @align: The required alignment for the objects. 399 * @flags: SLAB flags 400 * @ctor: A constructor for the objects. 401 * 402 * Cannot be called within a interrupt, but can be interrupted. 403 * The @ctor is run when new pages are allocated by the cache. 404 * 405 * The flags are 406 * 407 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 408 * to catch references to uninitialised memory. 409 * 410 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 411 * for buffer overruns. 412 * 413 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 414 * cacheline. This can be beneficial if you're counting cycles as closely 415 * as davem. 416 * 417 * Return: a pointer to the cache on success, NULL on failure. 418 */ 419 struct kmem_cache * 420 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 421 slab_flags_t flags, void (*ctor)(void *)) 422 { 423 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 424 ctor); 425 } 426 EXPORT_SYMBOL(kmem_cache_create); 427 428 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 429 { 430 LIST_HEAD(to_destroy); 431 struct kmem_cache *s, *s2; 432 433 /* 434 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 435 * @slab_caches_to_rcu_destroy list. The slab pages are freed 436 * through RCU and the associated kmem_cache are dereferenced 437 * while freeing the pages, so the kmem_caches should be freed only 438 * after the pending RCU operations are finished. As rcu_barrier() 439 * is a pretty slow operation, we batch all pending destructions 440 * asynchronously. 441 */ 442 mutex_lock(&slab_mutex); 443 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 444 mutex_unlock(&slab_mutex); 445 446 if (list_empty(&to_destroy)) 447 return; 448 449 rcu_barrier(); 450 451 list_for_each_entry_safe(s, s2, &to_destroy, list) { 452 kfence_shutdown_cache(s); 453 #ifdef SLAB_SUPPORTS_SYSFS 454 sysfs_slab_release(s); 455 #else 456 slab_kmem_cache_release(s); 457 #endif 458 } 459 } 460 461 static int shutdown_cache(struct kmem_cache *s) 462 { 463 /* free asan quarantined objects */ 464 kasan_cache_shutdown(s); 465 466 if (__kmem_cache_shutdown(s) != 0) 467 return -EBUSY; 468 469 list_del(&s->list); 470 471 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 472 #ifdef SLAB_SUPPORTS_SYSFS 473 sysfs_slab_unlink(s); 474 #endif 475 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 476 schedule_work(&slab_caches_to_rcu_destroy_work); 477 } else { 478 kfence_shutdown_cache(s); 479 #ifdef SLAB_SUPPORTS_SYSFS 480 sysfs_slab_unlink(s); 481 sysfs_slab_release(s); 482 #else 483 slab_kmem_cache_release(s); 484 #endif 485 } 486 487 return 0; 488 } 489 490 void slab_kmem_cache_release(struct kmem_cache *s) 491 { 492 __kmem_cache_release(s); 493 kfree_const(s->name); 494 kmem_cache_free(kmem_cache, s); 495 } 496 497 void kmem_cache_destroy(struct kmem_cache *s) 498 { 499 int err; 500 501 if (unlikely(!s)) 502 return; 503 504 mutex_lock(&slab_mutex); 505 506 s->refcount--; 507 if (s->refcount) 508 goto out_unlock; 509 510 err = shutdown_cache(s); 511 if (err) { 512 pr_err("kmem_cache_destroy %s: Slab cache still has objects\n", 513 s->name); 514 dump_stack(); 515 } 516 out_unlock: 517 mutex_unlock(&slab_mutex); 518 } 519 EXPORT_SYMBOL(kmem_cache_destroy); 520 521 /** 522 * kmem_cache_shrink - Shrink a cache. 523 * @cachep: The cache to shrink. 524 * 525 * Releases as many slabs as possible for a cache. 526 * To help debugging, a zero exit status indicates all slabs were released. 527 * 528 * Return: %0 if all slabs were released, non-zero otherwise 529 */ 530 int kmem_cache_shrink(struct kmem_cache *cachep) 531 { 532 int ret; 533 534 535 kasan_cache_shrink(cachep); 536 ret = __kmem_cache_shrink(cachep); 537 538 return ret; 539 } 540 EXPORT_SYMBOL(kmem_cache_shrink); 541 542 bool slab_is_available(void) 543 { 544 return slab_state >= UP; 545 } 546 547 #ifdef CONFIG_PRINTK 548 /** 549 * kmem_valid_obj - does the pointer reference a valid slab object? 550 * @object: pointer to query. 551 * 552 * Return: %true if the pointer is to a not-yet-freed object from 553 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 554 * is to an already-freed object, and %false otherwise. 555 */ 556 bool kmem_valid_obj(void *object) 557 { 558 struct page *page; 559 560 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 561 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 562 return false; 563 page = virt_to_head_page(object); 564 return PageSlab(page); 565 } 566 EXPORT_SYMBOL_GPL(kmem_valid_obj); 567 568 /** 569 * kmem_dump_obj - Print available slab provenance information 570 * @object: slab object for which to find provenance information. 571 * 572 * This function uses pr_cont(), so that the caller is expected to have 573 * printed out whatever preamble is appropriate. The provenance information 574 * depends on the type of object and on how much debugging is enabled. 575 * For a slab-cache object, the fact that it is a slab object is printed, 576 * and, if available, the slab name, return address, and stack trace from 577 * the allocation of that object. 578 * 579 * This function will splat if passed a pointer to a non-slab object. 580 * If you are not sure what type of object you have, you should instead 581 * use mem_dump_obj(). 582 */ 583 void kmem_dump_obj(void *object) 584 { 585 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 586 int i; 587 struct page *page; 588 unsigned long ptroffset; 589 struct kmem_obj_info kp = { }; 590 591 if (WARN_ON_ONCE(!virt_addr_valid(object))) 592 return; 593 page = virt_to_head_page(object); 594 if (WARN_ON_ONCE(!PageSlab(page))) { 595 pr_cont(" non-slab memory.\n"); 596 return; 597 } 598 kmem_obj_info(&kp, object, page); 599 if (kp.kp_slab_cache) 600 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 601 else 602 pr_cont(" slab%s", cp); 603 if (kp.kp_objp) 604 pr_cont(" start %px", kp.kp_objp); 605 if (kp.kp_data_offset) 606 pr_cont(" data offset %lu", kp.kp_data_offset); 607 if (kp.kp_objp) { 608 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 609 pr_cont(" pointer offset %lu", ptroffset); 610 } 611 if (kp.kp_slab_cache && kp.kp_slab_cache->usersize) 612 pr_cont(" size %u", kp.kp_slab_cache->usersize); 613 if (kp.kp_ret) 614 pr_cont(" allocated at %pS\n", kp.kp_ret); 615 else 616 pr_cont("\n"); 617 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 618 if (!kp.kp_stack[i]) 619 break; 620 pr_info(" %pS\n", kp.kp_stack[i]); 621 } 622 } 623 EXPORT_SYMBOL_GPL(kmem_dump_obj); 624 #endif 625 626 #ifndef CONFIG_SLOB 627 /* Create a cache during boot when no slab services are available yet */ 628 void __init create_boot_cache(struct kmem_cache *s, const char *name, 629 unsigned int size, slab_flags_t flags, 630 unsigned int useroffset, unsigned int usersize) 631 { 632 int err; 633 unsigned int align = ARCH_KMALLOC_MINALIGN; 634 635 s->name = name; 636 s->size = s->object_size = size; 637 638 /* 639 * For power of two sizes, guarantee natural alignment for kmalloc 640 * caches, regardless of SL*B debugging options. 641 */ 642 if (is_power_of_2(size)) 643 align = max(align, size); 644 s->align = calculate_alignment(flags, align, size); 645 646 s->useroffset = useroffset; 647 s->usersize = usersize; 648 649 err = __kmem_cache_create(s, flags); 650 651 if (err) 652 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 653 name, size, err); 654 655 s->refcount = -1; /* Exempt from merging for now */ 656 } 657 658 struct kmem_cache *__init create_kmalloc_cache(const char *name, 659 unsigned int size, slab_flags_t flags, 660 unsigned int useroffset, unsigned int usersize) 661 { 662 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 663 664 if (!s) 665 panic("Out of memory when creating slab %s\n", name); 666 667 create_boot_cache(s, name, size, flags, useroffset, usersize); 668 kasan_cache_create_kmalloc(s); 669 list_add(&s->list, &slab_caches); 670 s->refcount = 1; 671 return s; 672 } 673 674 struct kmem_cache * 675 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 676 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 677 EXPORT_SYMBOL(kmalloc_caches); 678 679 /* 680 * Conversion table for small slabs sizes / 8 to the index in the 681 * kmalloc array. This is necessary for slabs < 192 since we have non power 682 * of two cache sizes there. The size of larger slabs can be determined using 683 * fls. 684 */ 685 static u8 size_index[24] __ro_after_init = { 686 3, /* 8 */ 687 4, /* 16 */ 688 5, /* 24 */ 689 5, /* 32 */ 690 6, /* 40 */ 691 6, /* 48 */ 692 6, /* 56 */ 693 6, /* 64 */ 694 1, /* 72 */ 695 1, /* 80 */ 696 1, /* 88 */ 697 1, /* 96 */ 698 7, /* 104 */ 699 7, /* 112 */ 700 7, /* 120 */ 701 7, /* 128 */ 702 2, /* 136 */ 703 2, /* 144 */ 704 2, /* 152 */ 705 2, /* 160 */ 706 2, /* 168 */ 707 2, /* 176 */ 708 2, /* 184 */ 709 2 /* 192 */ 710 }; 711 712 static inline unsigned int size_index_elem(unsigned int bytes) 713 { 714 return (bytes - 1) / 8; 715 } 716 717 /* 718 * Find the kmem_cache structure that serves a given size of 719 * allocation 720 */ 721 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 722 { 723 unsigned int index; 724 725 if (size <= 192) { 726 if (!size) 727 return ZERO_SIZE_PTR; 728 729 index = size_index[size_index_elem(size)]; 730 } else { 731 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 732 return NULL; 733 index = fls(size - 1); 734 } 735 736 return kmalloc_caches[kmalloc_type(flags)][index]; 737 } 738 739 #ifdef CONFIG_ZONE_DMA 740 #define INIT_KMALLOC_INFO(__size, __short_size) \ 741 { \ 742 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 743 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 744 .name[KMALLOC_DMA] = "dma-kmalloc-" #__short_size, \ 745 .size = __size, \ 746 } 747 #else 748 #define INIT_KMALLOC_INFO(__size, __short_size) \ 749 { \ 750 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 751 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 752 .size = __size, \ 753 } 754 #endif 755 756 /* 757 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 758 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is 759 * kmalloc-67108864. 760 */ 761 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 762 INIT_KMALLOC_INFO(0, 0), 763 INIT_KMALLOC_INFO(96, 96), 764 INIT_KMALLOC_INFO(192, 192), 765 INIT_KMALLOC_INFO(8, 8), 766 INIT_KMALLOC_INFO(16, 16), 767 INIT_KMALLOC_INFO(32, 32), 768 INIT_KMALLOC_INFO(64, 64), 769 INIT_KMALLOC_INFO(128, 128), 770 INIT_KMALLOC_INFO(256, 256), 771 INIT_KMALLOC_INFO(512, 512), 772 INIT_KMALLOC_INFO(1024, 1k), 773 INIT_KMALLOC_INFO(2048, 2k), 774 INIT_KMALLOC_INFO(4096, 4k), 775 INIT_KMALLOC_INFO(8192, 8k), 776 INIT_KMALLOC_INFO(16384, 16k), 777 INIT_KMALLOC_INFO(32768, 32k), 778 INIT_KMALLOC_INFO(65536, 64k), 779 INIT_KMALLOC_INFO(131072, 128k), 780 INIT_KMALLOC_INFO(262144, 256k), 781 INIT_KMALLOC_INFO(524288, 512k), 782 INIT_KMALLOC_INFO(1048576, 1M), 783 INIT_KMALLOC_INFO(2097152, 2M), 784 INIT_KMALLOC_INFO(4194304, 4M), 785 INIT_KMALLOC_INFO(8388608, 8M), 786 INIT_KMALLOC_INFO(16777216, 16M), 787 INIT_KMALLOC_INFO(33554432, 32M), 788 INIT_KMALLOC_INFO(67108864, 64M) 789 }; 790 791 /* 792 * Patch up the size_index table if we have strange large alignment 793 * requirements for the kmalloc array. This is only the case for 794 * MIPS it seems. The standard arches will not generate any code here. 795 * 796 * Largest permitted alignment is 256 bytes due to the way we 797 * handle the index determination for the smaller caches. 798 * 799 * Make sure that nothing crazy happens if someone starts tinkering 800 * around with ARCH_KMALLOC_MINALIGN 801 */ 802 void __init setup_kmalloc_cache_index_table(void) 803 { 804 unsigned int i; 805 806 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 807 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); 808 809 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 810 unsigned int elem = size_index_elem(i); 811 812 if (elem >= ARRAY_SIZE(size_index)) 813 break; 814 size_index[elem] = KMALLOC_SHIFT_LOW; 815 } 816 817 if (KMALLOC_MIN_SIZE >= 64) { 818 /* 819 * The 96 byte size cache is not used if the alignment 820 * is 64 byte. 821 */ 822 for (i = 64 + 8; i <= 96; i += 8) 823 size_index[size_index_elem(i)] = 7; 824 825 } 826 827 if (KMALLOC_MIN_SIZE >= 128) { 828 /* 829 * The 192 byte sized cache is not used if the alignment 830 * is 128 byte. Redirect kmalloc to use the 256 byte cache 831 * instead. 832 */ 833 for (i = 128 + 8; i <= 192; i += 8) 834 size_index[size_index_elem(i)] = 8; 835 } 836 } 837 838 static void __init 839 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 840 { 841 if (type == KMALLOC_RECLAIM) 842 flags |= SLAB_RECLAIM_ACCOUNT; 843 844 kmalloc_caches[type][idx] = create_kmalloc_cache( 845 kmalloc_info[idx].name[type], 846 kmalloc_info[idx].size, flags, 0, 847 kmalloc_info[idx].size); 848 } 849 850 /* 851 * Create the kmalloc array. Some of the regular kmalloc arrays 852 * may already have been created because they were needed to 853 * enable allocations for slab creation. 854 */ 855 void __init create_kmalloc_caches(slab_flags_t flags) 856 { 857 int i; 858 enum kmalloc_cache_type type; 859 860 for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) { 861 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 862 if (!kmalloc_caches[type][i]) 863 new_kmalloc_cache(i, type, flags); 864 865 /* 866 * Caches that are not of the two-to-the-power-of size. 867 * These have to be created immediately after the 868 * earlier power of two caches 869 */ 870 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 871 !kmalloc_caches[type][1]) 872 new_kmalloc_cache(1, type, flags); 873 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 874 !kmalloc_caches[type][2]) 875 new_kmalloc_cache(2, type, flags); 876 } 877 } 878 879 /* Kmalloc array is now usable */ 880 slab_state = UP; 881 882 #ifdef CONFIG_ZONE_DMA 883 for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { 884 struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i]; 885 886 if (s) { 887 kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( 888 kmalloc_info[i].name[KMALLOC_DMA], 889 kmalloc_info[i].size, 890 SLAB_CACHE_DMA | flags, 0, 891 kmalloc_info[i].size); 892 } 893 } 894 #endif 895 } 896 #endif /* !CONFIG_SLOB */ 897 898 gfp_t kmalloc_fix_flags(gfp_t flags) 899 { 900 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 901 902 flags &= ~GFP_SLAB_BUG_MASK; 903 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 904 invalid_mask, &invalid_mask, flags, &flags); 905 dump_stack(); 906 907 return flags; 908 } 909 910 /* 911 * To avoid unnecessary overhead, we pass through large allocation requests 912 * directly to the page allocator. We use __GFP_COMP, because we will need to 913 * know the allocation order to free the pages properly in kfree. 914 */ 915 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 916 { 917 void *ret = NULL; 918 struct page *page; 919 920 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 921 flags = kmalloc_fix_flags(flags); 922 923 flags |= __GFP_COMP; 924 page = alloc_pages(flags, order); 925 if (likely(page)) { 926 ret = page_address(page); 927 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, 928 PAGE_SIZE << order); 929 } 930 ret = kasan_kmalloc_large(ret, size, flags); 931 /* As ret might get tagged, call kmemleak hook after KASAN. */ 932 kmemleak_alloc(ret, size, 1, flags); 933 return ret; 934 } 935 EXPORT_SYMBOL(kmalloc_order); 936 937 #ifdef CONFIG_TRACING 938 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 939 { 940 void *ret = kmalloc_order(size, flags, order); 941 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags); 942 return ret; 943 } 944 EXPORT_SYMBOL(kmalloc_order_trace); 945 #endif 946 947 #ifdef CONFIG_SLAB_FREELIST_RANDOM 948 /* Randomize a generic freelist */ 949 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 950 unsigned int count) 951 { 952 unsigned int rand; 953 unsigned int i; 954 955 for (i = 0; i < count; i++) 956 list[i] = i; 957 958 /* Fisher-Yates shuffle */ 959 for (i = count - 1; i > 0; i--) { 960 rand = prandom_u32_state(state); 961 rand %= (i + 1); 962 swap(list[i], list[rand]); 963 } 964 } 965 966 /* Create a random sequence per cache */ 967 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 968 gfp_t gfp) 969 { 970 struct rnd_state state; 971 972 if (count < 2 || cachep->random_seq) 973 return 0; 974 975 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 976 if (!cachep->random_seq) 977 return -ENOMEM; 978 979 /* Get best entropy at this stage of boot */ 980 prandom_seed_state(&state, get_random_long()); 981 982 freelist_randomize(&state, cachep->random_seq, count); 983 return 0; 984 } 985 986 /* Destroy the per-cache random freelist sequence */ 987 void cache_random_seq_destroy(struct kmem_cache *cachep) 988 { 989 kfree(cachep->random_seq); 990 cachep->random_seq = NULL; 991 } 992 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 993 994 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 995 #ifdef CONFIG_SLAB 996 #define SLABINFO_RIGHTS (0600) 997 #else 998 #define SLABINFO_RIGHTS (0400) 999 #endif 1000 1001 static void print_slabinfo_header(struct seq_file *m) 1002 { 1003 /* 1004 * Output format version, so at least we can change it 1005 * without _too_ many complaints. 1006 */ 1007 #ifdef CONFIG_DEBUG_SLAB 1008 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1009 #else 1010 seq_puts(m, "slabinfo - version: 2.1\n"); 1011 #endif 1012 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1013 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1014 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1015 #ifdef CONFIG_DEBUG_SLAB 1016 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1017 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1018 #endif 1019 seq_putc(m, '\n'); 1020 } 1021 1022 void *slab_start(struct seq_file *m, loff_t *pos) 1023 { 1024 mutex_lock(&slab_mutex); 1025 return seq_list_start(&slab_caches, *pos); 1026 } 1027 1028 void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1029 { 1030 return seq_list_next(p, &slab_caches, pos); 1031 } 1032 1033 void slab_stop(struct seq_file *m, void *p) 1034 { 1035 mutex_unlock(&slab_mutex); 1036 } 1037 1038 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1039 { 1040 struct slabinfo sinfo; 1041 1042 memset(&sinfo, 0, sizeof(sinfo)); 1043 get_slabinfo(s, &sinfo); 1044 1045 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1046 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1047 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1048 1049 seq_printf(m, " : tunables %4u %4u %4u", 1050 sinfo.limit, sinfo.batchcount, sinfo.shared); 1051 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1052 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1053 slabinfo_show_stats(m, s); 1054 seq_putc(m, '\n'); 1055 } 1056 1057 static int slab_show(struct seq_file *m, void *p) 1058 { 1059 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1060 1061 if (p == slab_caches.next) 1062 print_slabinfo_header(m); 1063 cache_show(s, m); 1064 return 0; 1065 } 1066 1067 void dump_unreclaimable_slab(void) 1068 { 1069 struct kmem_cache *s; 1070 struct slabinfo sinfo; 1071 1072 /* 1073 * Here acquiring slab_mutex is risky since we don't prefer to get 1074 * sleep in oom path. But, without mutex hold, it may introduce a 1075 * risk of crash. 1076 * Use mutex_trylock to protect the list traverse, dump nothing 1077 * without acquiring the mutex. 1078 */ 1079 if (!mutex_trylock(&slab_mutex)) { 1080 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1081 return; 1082 } 1083 1084 pr_info("Unreclaimable slab info:\n"); 1085 pr_info("Name Used Total\n"); 1086 1087 list_for_each_entry(s, &slab_caches, list) { 1088 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1089 continue; 1090 1091 get_slabinfo(s, &sinfo); 1092 1093 if (sinfo.num_objs > 0) 1094 pr_info("%-17s %10luKB %10luKB\n", s->name, 1095 (sinfo.active_objs * s->size) / 1024, 1096 (sinfo.num_objs * s->size) / 1024); 1097 } 1098 mutex_unlock(&slab_mutex); 1099 } 1100 1101 #if defined(CONFIG_MEMCG_KMEM) 1102 int memcg_slab_show(struct seq_file *m, void *p) 1103 { 1104 /* 1105 * Deprecated. 1106 * Please, take a look at tools/cgroup/slabinfo.py . 1107 */ 1108 return 0; 1109 } 1110 #endif 1111 1112 /* 1113 * slabinfo_op - iterator that generates /proc/slabinfo 1114 * 1115 * Output layout: 1116 * cache-name 1117 * num-active-objs 1118 * total-objs 1119 * object size 1120 * num-active-slabs 1121 * total-slabs 1122 * num-pages-per-slab 1123 * + further values on SMP and with statistics enabled 1124 */ 1125 static const struct seq_operations slabinfo_op = { 1126 .start = slab_start, 1127 .next = slab_next, 1128 .stop = slab_stop, 1129 .show = slab_show, 1130 }; 1131 1132 static int slabinfo_open(struct inode *inode, struct file *file) 1133 { 1134 return seq_open(file, &slabinfo_op); 1135 } 1136 1137 static const struct proc_ops slabinfo_proc_ops = { 1138 .proc_flags = PROC_ENTRY_PERMANENT, 1139 .proc_open = slabinfo_open, 1140 .proc_read = seq_read, 1141 .proc_write = slabinfo_write, 1142 .proc_lseek = seq_lseek, 1143 .proc_release = seq_release, 1144 }; 1145 1146 static int __init slab_proc_init(void) 1147 { 1148 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1149 return 0; 1150 } 1151 module_init(slab_proc_init); 1152 1153 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1154 1155 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1156 gfp_t flags) 1157 { 1158 void *ret; 1159 size_t ks; 1160 1161 /* Don't use instrumented ksize to allow precise KASAN poisoning. */ 1162 if (likely(!ZERO_OR_NULL_PTR(p))) { 1163 if (!kasan_check_byte(p)) 1164 return NULL; 1165 ks = kfence_ksize(p) ?: __ksize(p); 1166 } else 1167 ks = 0; 1168 1169 /* If the object still fits, repoison it precisely. */ 1170 if (ks >= new_size) { 1171 p = kasan_krealloc((void *)p, new_size, flags); 1172 return (void *)p; 1173 } 1174 1175 ret = kmalloc_track_caller(new_size, flags); 1176 if (ret && p) { 1177 /* Disable KASAN checks as the object's redzone is accessed. */ 1178 kasan_disable_current(); 1179 memcpy(ret, kasan_reset_tag(p), ks); 1180 kasan_enable_current(); 1181 } 1182 1183 return ret; 1184 } 1185 1186 /** 1187 * krealloc - reallocate memory. The contents will remain unchanged. 1188 * @p: object to reallocate memory for. 1189 * @new_size: how many bytes of memory are required. 1190 * @flags: the type of memory to allocate. 1191 * 1192 * The contents of the object pointed to are preserved up to the 1193 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1194 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1195 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1196 * 1197 * Return: pointer to the allocated memory or %NULL in case of error 1198 */ 1199 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1200 { 1201 void *ret; 1202 1203 if (unlikely(!new_size)) { 1204 kfree(p); 1205 return ZERO_SIZE_PTR; 1206 } 1207 1208 ret = __do_krealloc(p, new_size, flags); 1209 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1210 kfree(p); 1211 1212 return ret; 1213 } 1214 EXPORT_SYMBOL(krealloc); 1215 1216 /** 1217 * kfree_sensitive - Clear sensitive information in memory before freeing 1218 * @p: object to free memory of 1219 * 1220 * The memory of the object @p points to is zeroed before freed. 1221 * If @p is %NULL, kfree_sensitive() does nothing. 1222 * 1223 * Note: this function zeroes the whole allocated buffer which can be a good 1224 * deal bigger than the requested buffer size passed to kmalloc(). So be 1225 * careful when using this function in performance sensitive code. 1226 */ 1227 void kfree_sensitive(const void *p) 1228 { 1229 size_t ks; 1230 void *mem = (void *)p; 1231 1232 ks = ksize(mem); 1233 if (ks) 1234 memzero_explicit(mem, ks); 1235 kfree(mem); 1236 } 1237 EXPORT_SYMBOL(kfree_sensitive); 1238 1239 /** 1240 * ksize - get the actual amount of memory allocated for a given object 1241 * @objp: Pointer to the object 1242 * 1243 * kmalloc may internally round up allocations and return more memory 1244 * than requested. ksize() can be used to determine the actual amount of 1245 * memory allocated. The caller may use this additional memory, even though 1246 * a smaller amount of memory was initially specified with the kmalloc call. 1247 * The caller must guarantee that objp points to a valid object previously 1248 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1249 * must not be freed during the duration of the call. 1250 * 1251 * Return: size of the actual memory used by @objp in bytes 1252 */ 1253 size_t ksize(const void *objp) 1254 { 1255 size_t size; 1256 1257 /* 1258 * We need to first check that the pointer to the object is valid, and 1259 * only then unpoison the memory. The report printed from ksize() is 1260 * more useful, then when it's printed later when the behaviour could 1261 * be undefined due to a potential use-after-free or double-free. 1262 * 1263 * We use kasan_check_byte(), which is supported for the hardware 1264 * tag-based KASAN mode, unlike kasan_check_read/write(). 1265 * 1266 * If the pointed to memory is invalid, we return 0 to avoid users of 1267 * ksize() writing to and potentially corrupting the memory region. 1268 * 1269 * We want to perform the check before __ksize(), to avoid potentially 1270 * crashing in __ksize() due to accessing invalid metadata. 1271 */ 1272 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1273 return 0; 1274 1275 size = kfence_ksize(objp) ?: __ksize(objp); 1276 /* 1277 * We assume that ksize callers could use whole allocated area, 1278 * so we need to unpoison this area. 1279 */ 1280 kasan_unpoison_range(objp, size); 1281 return size; 1282 } 1283 EXPORT_SYMBOL(ksize); 1284 1285 /* Tracepoints definitions. */ 1286 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1287 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1288 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1289 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1290 EXPORT_TRACEPOINT_SYMBOL(kfree); 1291 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1292 1293 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1294 { 1295 if (__should_failslab(s, gfpflags)) 1296 return -ENOMEM; 1297 return 0; 1298 } 1299 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1300