linux/mm/slab_common.c
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   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
  35enum slab_state slab_state;
  36LIST_HEAD(slab_caches);
  37DEFINE_MUTEX(slab_mutex);
  38struct kmem_cache *kmem_cache;
  39
  40#ifdef CONFIG_HARDENED_USERCOPY
  41bool usercopy_fallback __ro_after_init =
  42                IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK);
  43module_param(usercopy_fallback, bool, 0400);
  44MODULE_PARM_DESC(usercopy_fallback,
  45                "WARN instead of reject usercopy whitelist violations");
  46#endif
  47
  48static LIST_HEAD(slab_caches_to_rcu_destroy);
  49static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work);
  50static 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 */
  66static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
  67
  68static int __init setup_slab_nomerge(char *str)
  69{
  70        slab_nomerge = true;
  71        return 1;
  72}
  73
  74static 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 */
  91unsigned int kmem_cache_size(struct kmem_cache *s)
  92{
  93        return s->object_size;
  94}
  95EXPORT_SYMBOL(kmem_cache_size);
  96
  97#ifdef CONFIG_DEBUG_VM
  98static int kmem_cache_sanity_check(const char *name, unsigned int size)
  99{
 100        if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
 101                pr_err("kmem_cache_create(%s) integrity check failed\n", name);
 102                return -EINVAL;
 103        }
 104
 105        WARN_ON(strchr(name, ' '));     /* It confuses parsers */
 106        return 0;
 107}
 108#else
 109static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
 110{
 111        return 0;
 112}
 113#endif
 114
 115void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
 116{
 117        size_t i;
 118
 119        for (i = 0; i < nr; i++) {
 120                if (s)
 121                        kmem_cache_free(s, p[i]);
 122                else
 123                        kfree(p[i]);
 124        }
 125}
 126
 127int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
 128                                                                void **p)
 129{
 130        size_t i;
 131
 132        for (i = 0; i < nr; i++) {
 133                void *x = p[i] = kmem_cache_alloc(s, flags);
 134                if (!x) {
 135                        __kmem_cache_free_bulk(s, i, p);
 136                        return 0;
 137                }
 138        }
 139        return i;
 140}
 141
 142/*
 143 * Figure out what the alignment of the objects will be given a set of
 144 * flags, a user specified alignment and the size of the objects.
 145 */
 146static unsigned int calculate_alignment(slab_flags_t flags,
 147                unsigned int align, unsigned int size)
 148{
 149        /*
 150         * If the user wants hardware cache aligned objects then follow that
 151         * suggestion if the object is sufficiently large.
 152         *
 153         * The hardware cache alignment cannot override the specified
 154         * alignment though. If that is greater then use it.
 155         */
 156        if (flags & SLAB_HWCACHE_ALIGN) {
 157                unsigned int ralign;
 158
 159                ralign = cache_line_size();
 160                while (size <= ralign / 2)
 161                        ralign /= 2;
 162                align = max(align, ralign);
 163        }
 164
 165        if (align < ARCH_SLAB_MINALIGN)
 166                align = ARCH_SLAB_MINALIGN;
 167
 168        return ALIGN(align, sizeof(void *));
 169}
 170
 171/*
 172 * Find a mergeable slab cache
 173 */
 174int slab_unmergeable(struct kmem_cache *s)
 175{
 176        if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
 177                return 1;
 178
 179        if (s->ctor)
 180                return 1;
 181
 182        if (s->usersize)
 183                return 1;
 184
 185        /*
 186         * We may have set a slab to be unmergeable during bootstrap.
 187         */
 188        if (s->refcount < 0)
 189                return 1;
 190
 191        return 0;
 192}
 193
 194struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
 195                slab_flags_t flags, const char *name, void (*ctor)(void *))
 196{
 197        struct kmem_cache *s;
 198
 199        if (slab_nomerge)
 200                return NULL;
 201
 202        if (ctor)
 203                return NULL;
 204
 205        size = ALIGN(size, sizeof(void *));
 206        align = calculate_alignment(flags, align, size);
 207        size = ALIGN(size, align);
 208        flags = kmem_cache_flags(size, flags, name);
 209
 210        if (flags & SLAB_NEVER_MERGE)
 211                return NULL;
 212
 213        list_for_each_entry_reverse(s, &slab_caches, list) {
 214                if (slab_unmergeable(s))
 215                        continue;
 216
 217                if (size > s->size)
 218                        continue;
 219
 220                if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
 221                        continue;
 222                /*
 223                 * Check if alignment is compatible.
 224                 * Courtesy of Adrian Drzewiecki
 225                 */
 226                if ((s->size & ~(align - 1)) != s->size)
 227                        continue;
 228
 229                if (s->size - size >= sizeof(void *))
 230                        continue;
 231
 232                if (IS_ENABLED(CONFIG_SLAB) && align &&
 233                        (align > s->align || s->align % align))
 234                        continue;
 235
 236                return s;
 237        }
 238        return NULL;
 239}
 240
 241static struct kmem_cache *create_cache(const char *name,
 242                unsigned int object_size, unsigned int align,
 243                slab_flags_t flags, unsigned int useroffset,
 244                unsigned int usersize, void (*ctor)(void *),
 245                struct kmem_cache *root_cache)
 246{
 247        struct kmem_cache *s;
 248        int err;
 249
 250        if (WARN_ON(useroffset + usersize > object_size))
 251                useroffset = usersize = 0;
 252
 253        err = -ENOMEM;
 254        s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 255        if (!s)
 256                goto out;
 257
 258        s->name = name;
 259        s->size = s->object_size = object_size;
 260        s->align = align;
 261        s->ctor = ctor;
 262        s->useroffset = useroffset;
 263        s->usersize = usersize;
 264
 265        err = __kmem_cache_create(s, flags);
 266        if (err)
 267                goto out_free_cache;
 268
 269        s->refcount = 1;
 270        list_add(&s->list, &slab_caches);
 271out:
 272        if (err)
 273                return ERR_PTR(err);
 274        return s;
 275
 276out_free_cache:
 277        kmem_cache_free(kmem_cache, s);
 278        goto out;
 279}
 280
 281/**
 282 * kmem_cache_create_usercopy - Create a cache with a region suitable
 283 * for copying to userspace
 284 * @name: A string which is used in /proc/slabinfo to identify this cache.
 285 * @size: The size of objects to be created in this cache.
 286 * @align: The required alignment for the objects.
 287 * @flags: SLAB flags
 288 * @useroffset: Usercopy region offset
 289 * @usersize: Usercopy region size
 290 * @ctor: A constructor for the objects.
 291 *
 292 * Cannot be called within a interrupt, but can be interrupted.
 293 * The @ctor is run when new pages are allocated by the cache.
 294 *
 295 * The flags are
 296 *
 297 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
 298 * to catch references to uninitialised memory.
 299 *
 300 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
 301 * for buffer overruns.
 302 *
 303 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
 304 * cacheline.  This can be beneficial if you're counting cycles as closely
 305 * as davem.
 306 *
 307 * Return: a pointer to the cache on success, NULL on failure.
 308 */
 309struct kmem_cache *
 310kmem_cache_create_usercopy(const char *name,
 311                  unsigned int size, unsigned int align,
 312                  slab_flags_t flags,
 313                  unsigned int useroffset, unsigned int usersize,
 314                  void (*ctor)(void *))
 315{
 316        struct kmem_cache *s = NULL;
 317        const char *cache_name;
 318        int err;
 319
 320#ifdef CONFIG_SLUB_DEBUG
 321        /*
 322         * If no slub_debug was enabled globally, the static key is not yet
 323         * enabled by setup_slub_debug(). Enable it if the cache is being
 324         * created with any of the debugging flags passed explicitly.
 325         */
 326        if (flags & SLAB_DEBUG_FLAGS)
 327                static_branch_enable(&slub_debug_enabled);
 328#endif
 329
 330        mutex_lock(&slab_mutex);
 331
 332        err = kmem_cache_sanity_check(name, size);
 333        if (err) {
 334                goto out_unlock;
 335        }
 336
 337        /* Refuse requests with allocator specific flags */
 338        if (flags & ~SLAB_FLAGS_PERMITTED) {
 339                err = -EINVAL;
 340                goto out_unlock;
 341        }
 342
 343        /*
 344         * Some allocators will constraint the set of valid flags to a subset
 345         * of all flags. We expect them to define CACHE_CREATE_MASK in this
 346         * case, and we'll just provide them with a sanitized version of the
 347         * passed flags.
 348         */
 349        flags &= CACHE_CREATE_MASK;
 350
 351        /* Fail closed on bad usersize of useroffset values. */
 352        if (WARN_ON(!usersize && useroffset) ||
 353            WARN_ON(size < usersize || size - usersize < useroffset))
 354                usersize = useroffset = 0;
 355
 356        if (!usersize)
 357                s = __kmem_cache_alias(name, size, align, flags, ctor);
 358        if (s)
 359                goto out_unlock;
 360
 361        cache_name = kstrdup_const(name, GFP_KERNEL);
 362        if (!cache_name) {
 363                err = -ENOMEM;
 364                goto out_unlock;
 365        }
 366
 367        s = create_cache(cache_name, size,
 368                         calculate_alignment(flags, align, size),
 369                         flags, useroffset, usersize, ctor, NULL);
 370        if (IS_ERR(s)) {
 371                err = PTR_ERR(s);
 372                kfree_const(cache_name);
 373        }
 374
 375out_unlock:
 376        mutex_unlock(&slab_mutex);
 377
 378        if (err) {
 379                if (flags & SLAB_PANIC)
 380                        panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 381                                name, err);
 382                else {
 383                        pr_warn("kmem_cache_create(%s) failed with error %d\n",
 384                                name, err);
 385                        dump_stack();
 386                }
 387                return NULL;
 388        }
 389        return s;
 390}
 391EXPORT_SYMBOL(kmem_cache_create_usercopy);
 392
 393/**
 394 * kmem_cache_create - Create a cache.
 395 * @name: A string which is used in /proc/slabinfo to identify this cache.
 396 * @size: The size of objects to be created in this cache.
 397 * @align: The required alignment for the objects.
 398 * @flags: SLAB flags
 399 * @ctor: A constructor for the objects.
 400 *
 401 * Cannot be called within a interrupt, but can be interrupted.
 402 * The @ctor is run when new pages are allocated by the cache.
 403 *
 404 * The flags are
 405 *
 406 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
 407 * to catch references to uninitialised memory.
 408 *
 409 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
 410 * for buffer overruns.
 411 *
 412 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
 413 * cacheline.  This can be beneficial if you're counting cycles as closely
 414 * as davem.
 415 *
 416 * Return: a pointer to the cache on success, NULL on failure.
 417 */
 418struct kmem_cache *
 419kmem_cache_create(const char *name, unsigned int size, unsigned int align,
 420                slab_flags_t flags, void (*ctor)(void *))
 421{
 422        return kmem_cache_create_usercopy(name, size, align, flags, 0, 0,
 423                                          ctor);
 424}
 425EXPORT_SYMBOL(kmem_cache_create);
 426
 427static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
 428{
 429        LIST_HEAD(to_destroy);
 430        struct kmem_cache *s, *s2;
 431
 432        /*
 433         * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
 434         * @slab_caches_to_rcu_destroy list.  The slab pages are freed
 435         * through RCU and the associated kmem_cache are dereferenced
 436         * while freeing the pages, so the kmem_caches should be freed only
 437         * after the pending RCU operations are finished.  As rcu_barrier()
 438         * is a pretty slow operation, we batch all pending destructions
 439         * asynchronously.
 440         */
 441        mutex_lock(&slab_mutex);
 442        list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
 443        mutex_unlock(&slab_mutex);
 444
 445        if (list_empty(&to_destroy))
 446                return;
 447
 448        rcu_barrier();
 449
 450        list_for_each_entry_safe(s, s2, &to_destroy, list) {
 451                kfence_shutdown_cache(s);
 452#ifdef SLAB_SUPPORTS_SYSFS
 453                sysfs_slab_release(s);
 454#else
 455                slab_kmem_cache_release(s);
 456#endif
 457        }
 458}
 459
 460static int shutdown_cache(struct kmem_cache *s)
 461{
 462        /* free asan quarantined objects */
 463        kasan_cache_shutdown(s);
 464
 465        if (__kmem_cache_shutdown(s) != 0)
 466                return -EBUSY;
 467
 468        list_del(&s->list);
 469
 470        if (s->flags & SLAB_TYPESAFE_BY_RCU) {
 471#ifdef SLAB_SUPPORTS_SYSFS
 472                sysfs_slab_unlink(s);
 473#endif
 474                list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
 475                schedule_work(&slab_caches_to_rcu_destroy_work);
 476        } else {
 477                kfence_shutdown_cache(s);
 478#ifdef SLAB_SUPPORTS_SYSFS
 479                sysfs_slab_unlink(s);
 480                sysfs_slab_release(s);
 481#else
 482                slab_kmem_cache_release(s);
 483#endif
 484        }
 485
 486        return 0;
 487}
 488
 489void slab_kmem_cache_release(struct kmem_cache *s)
 490{
 491        __kmem_cache_release(s);
 492        kfree_const(s->name);
 493        kmem_cache_free(kmem_cache, s);
 494}
 495
 496void kmem_cache_destroy(struct kmem_cache *s)
 497{
 498        int err;
 499
 500        if (unlikely(!s))
 501                return;
 502
 503        mutex_lock(&slab_mutex);
 504
 505        s->refcount--;
 506        if (s->refcount)
 507                goto out_unlock;
 508
 509        err = shutdown_cache(s);
 510        if (err) {
 511                pr_err("kmem_cache_destroy %s: Slab cache still has objects\n",
 512                       s->name);
 513                dump_stack();
 514        }
 515out_unlock:
 516        mutex_unlock(&slab_mutex);
 517}
 518EXPORT_SYMBOL(kmem_cache_destroy);
 519
 520/**
 521 * kmem_cache_shrink - Shrink a cache.
 522 * @cachep: The cache to shrink.
 523 *
 524 * Releases as many slabs as possible for a cache.
 525 * To help debugging, a zero exit status indicates all slabs were released.
 526 *
 527 * Return: %0 if all slabs were released, non-zero otherwise
 528 */
 529int kmem_cache_shrink(struct kmem_cache *cachep)
 530{
 531        int ret;
 532
 533
 534        kasan_cache_shrink(cachep);
 535        ret = __kmem_cache_shrink(cachep);
 536
 537        return ret;
 538}
 539EXPORT_SYMBOL(kmem_cache_shrink);
 540
 541bool slab_is_available(void)
 542{
 543        return slab_state >= UP;
 544}
 545
 546#ifdef CONFIG_PRINTK
 547/**
 548 * kmem_valid_obj - does the pointer reference a valid slab object?
 549 * @object: pointer to query.
 550 *
 551 * Return: %true if the pointer is to a not-yet-freed object from
 552 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
 553 * is to an already-freed object, and %false otherwise.
 554 */
 555bool kmem_valid_obj(void *object)
 556{
 557        struct page *page;
 558
 559        /* Some arches consider ZERO_SIZE_PTR to be a valid address. */
 560        if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
 561                return false;
 562        page = virt_to_head_page(object);
 563        return PageSlab(page);
 564}
 565EXPORT_SYMBOL_GPL(kmem_valid_obj);
 566
 567/**
 568 * kmem_dump_obj - Print available slab provenance information
 569 * @object: slab object for which to find provenance information.
 570 *
 571 * This function uses pr_cont(), so that the caller is expected to have
 572 * printed out whatever preamble is appropriate.  The provenance information
 573 * depends on the type of object and on how much debugging is enabled.
 574 * For a slab-cache object, the fact that it is a slab object is printed,
 575 * and, if available, the slab name, return address, and stack trace from
 576 * the allocation of that object.
 577 *
 578 * This function will splat if passed a pointer to a non-slab object.
 579 * If you are not sure what type of object you have, you should instead
 580 * use mem_dump_obj().
 581 */
 582void kmem_dump_obj(void *object)
 583{
 584        char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
 585        int i;
 586        struct page *page;
 587        unsigned long ptroffset;
 588        struct kmem_obj_info kp = { };
 589
 590        if (WARN_ON_ONCE(!virt_addr_valid(object)))
 591                return;
 592        page = virt_to_head_page(object);
 593        if (WARN_ON_ONCE(!PageSlab(page))) {
 594                pr_cont(" non-slab memory.\n");
 595                return;
 596        }
 597        kmem_obj_info(&kp, object, page);
 598        if (kp.kp_slab_cache)
 599                pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
 600        else
 601                pr_cont(" slab%s", cp);
 602        if (kp.kp_objp)
 603                pr_cont(" start %px", kp.kp_objp);
 604        if (kp.kp_data_offset)
 605                pr_cont(" data offset %lu", kp.kp_data_offset);
 606        if (kp.kp_objp) {
 607                ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
 608                pr_cont(" pointer offset %lu", ptroffset);
 609        }
 610        if (kp.kp_slab_cache && kp.kp_slab_cache->usersize)
 611                pr_cont(" size %u", kp.kp_slab_cache->usersize);
 612        if (kp.kp_ret)
 613                pr_cont(" allocated at %pS\n", kp.kp_ret);
 614        else
 615                pr_cont("\n");
 616        for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
 617                if (!kp.kp_stack[i])
 618                        break;
 619                pr_info("    %pS\n", kp.kp_stack[i]);
 620        }
 621}
 622EXPORT_SYMBOL_GPL(kmem_dump_obj);
 623#endif
 624
 625#ifndef CONFIG_SLOB
 626/* Create a cache during boot when no slab services are available yet */
 627void __init create_boot_cache(struct kmem_cache *s, const char *name,
 628                unsigned int size, slab_flags_t flags,
 629                unsigned int useroffset, unsigned int usersize)
 630{
 631        int err;
 632        unsigned int align = ARCH_KMALLOC_MINALIGN;
 633
 634        s->name = name;
 635        s->size = s->object_size = size;
 636
 637        /*
 638         * For power of two sizes, guarantee natural alignment for kmalloc
 639         * caches, regardless of SL*B debugging options.
 640         */
 641        if (is_power_of_2(size))
 642                align = max(align, size);
 643        s->align = calculate_alignment(flags, align, size);
 644
 645        s->useroffset = useroffset;
 646        s->usersize = usersize;
 647
 648        err = __kmem_cache_create(s, flags);
 649
 650        if (err)
 651                panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
 652                                        name, size, err);
 653
 654        s->refcount = -1;       /* Exempt from merging for now */
 655}
 656
 657struct kmem_cache *__init create_kmalloc_cache(const char *name,
 658                unsigned int size, slab_flags_t flags,
 659                unsigned int useroffset, unsigned int usersize)
 660{
 661        struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
 662
 663        if (!s)
 664                panic("Out of memory when creating slab %s\n", name);
 665
 666        create_boot_cache(s, name, size, flags, useroffset, usersize);
 667        kasan_cache_create_kmalloc(s);
 668        list_add(&s->list, &slab_caches);
 669        s->refcount = 1;
 670        return s;
 671}
 672
 673struct kmem_cache *
 674kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
 675{ /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
 676EXPORT_SYMBOL(kmalloc_caches);
 677
 678/*
 679 * Conversion table for small slabs sizes / 8 to the index in the
 680 * kmalloc array. This is necessary for slabs < 192 since we have non power
 681 * of two cache sizes there. The size of larger slabs can be determined using
 682 * fls.
 683 */
 684static u8 size_index[24] __ro_after_init = {
 685        3,      /* 8 */
 686        4,      /* 16 */
 687        5,      /* 24 */
 688        5,      /* 32 */
 689        6,      /* 40 */
 690        6,      /* 48 */
 691        6,      /* 56 */
 692        6,      /* 64 */
 693        1,      /* 72 */
 694        1,      /* 80 */
 695        1,      /* 88 */
 696        1,      /* 96 */
 697        7,      /* 104 */
 698        7,      /* 112 */
 699        7,      /* 120 */
 700        7,      /* 128 */
 701        2,      /* 136 */
 702        2,      /* 144 */
 703        2,      /* 152 */
 704        2,      /* 160 */
 705        2,      /* 168 */
 706        2,      /* 176 */
 707        2,      /* 184 */
 708        2       /* 192 */
 709};
 710
 711static inline unsigned int size_index_elem(unsigned int bytes)
 712{
 713        return (bytes - 1) / 8;
 714}
 715
 716/*
 717 * Find the kmem_cache structure that serves a given size of
 718 * allocation
 719 */
 720struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 721{
 722        unsigned int index;
 723
 724        if (size <= 192) {
 725                if (!size)
 726                        return ZERO_SIZE_PTR;
 727
 728                index = size_index[size_index_elem(size)];
 729        } else {
 730                if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE))
 731                        return NULL;
 732                index = fls(size - 1);
 733        }
 734
 735        return kmalloc_caches[kmalloc_type(flags)][index];
 736}
 737
 738#ifdef CONFIG_ZONE_DMA
 739#define INIT_KMALLOC_INFO(__size, __short_size)                 \
 740{                                                               \
 741        .name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,      \
 742        .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size,  \
 743        .name[KMALLOC_DMA]     = "dma-kmalloc-" #__short_size,  \
 744        .size = __size,                                         \
 745}
 746#else
 747#define INIT_KMALLOC_INFO(__size, __short_size)                 \
 748{                                                               \
 749        .name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,      \
 750        .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size,  \
 751        .size = __size,                                         \
 752}
 753#endif
 754
 755/*
 756 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
 757 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
 758 * kmalloc-67108864.
 759 */
 760const struct kmalloc_info_struct kmalloc_info[] __initconst = {
 761        INIT_KMALLOC_INFO(0, 0),
 762        INIT_KMALLOC_INFO(96, 96),
 763        INIT_KMALLOC_INFO(192, 192),
 764        INIT_KMALLOC_INFO(8, 8),
 765        INIT_KMALLOC_INFO(16, 16),
 766        INIT_KMALLOC_INFO(32, 32),
 767        INIT_KMALLOC_INFO(64, 64),
 768        INIT_KMALLOC_INFO(128, 128),
 769        INIT_KMALLOC_INFO(256, 256),
 770        INIT_KMALLOC_INFO(512, 512),
 771        INIT_KMALLOC_INFO(1024, 1k),
 772        INIT_KMALLOC_INFO(2048, 2k),
 773        INIT_KMALLOC_INFO(4096, 4k),
 774        INIT_KMALLOC_INFO(8192, 8k),
 775        INIT_KMALLOC_INFO(16384, 16k),
 776        INIT_KMALLOC_INFO(32768, 32k),
 777        INIT_KMALLOC_INFO(65536, 64k),
 778        INIT_KMALLOC_INFO(131072, 128k),
 779        INIT_KMALLOC_INFO(262144, 256k),
 780        INIT_KMALLOC_INFO(524288, 512k),
 781        INIT_KMALLOC_INFO(1048576, 1M),
 782        INIT_KMALLOC_INFO(2097152, 2M),
 783        INIT_KMALLOC_INFO(4194304, 4M),
 784        INIT_KMALLOC_INFO(8388608, 8M),
 785        INIT_KMALLOC_INFO(16777216, 16M),
 786        INIT_KMALLOC_INFO(33554432, 32M),
 787        INIT_KMALLOC_INFO(67108864, 64M)
 788};
 789
 790/*
 791 * Patch up the size_index table if we have strange large alignment
 792 * requirements for the kmalloc array. This is only the case for
 793 * MIPS it seems. The standard arches will not generate any code here.
 794 *
 795 * Largest permitted alignment is 256 bytes due to the way we
 796 * handle the index determination for the smaller caches.
 797 *
 798 * Make sure that nothing crazy happens if someone starts tinkering
 799 * around with ARCH_KMALLOC_MINALIGN
 800 */
 801void __init setup_kmalloc_cache_index_table(void)
 802{
 803        unsigned int i;
 804
 805        BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 806                (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 807
 808        for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
 809                unsigned int elem = size_index_elem(i);
 810
 811                if (elem >= ARRAY_SIZE(size_index))
 812                        break;
 813                size_index[elem] = KMALLOC_SHIFT_LOW;
 814        }
 815
 816        if (KMALLOC_MIN_SIZE >= 64) {
 817                /*
 818                 * The 96 byte size cache is not used if the alignment
 819                 * is 64 byte.
 820                 */
 821                for (i = 64 + 8; i <= 96; i += 8)
 822                        size_index[size_index_elem(i)] = 7;
 823
 824        }
 825
 826        if (KMALLOC_MIN_SIZE >= 128) {
 827                /*
 828                 * The 192 byte sized cache is not used if the alignment
 829                 * is 128 byte. Redirect kmalloc to use the 256 byte cache
 830                 * instead.
 831                 */
 832                for (i = 128 + 8; i <= 192; i += 8)
 833                        size_index[size_index_elem(i)] = 8;
 834        }
 835}
 836
 837static void __init
 838new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
 839{
 840        if (type == KMALLOC_RECLAIM)
 841                flags |= SLAB_RECLAIM_ACCOUNT;
 842
 843        kmalloc_caches[type][idx] = create_kmalloc_cache(
 844                                        kmalloc_info[idx].name[type],
 845                                        kmalloc_info[idx].size, flags, 0,
 846                                        kmalloc_info[idx].size);
 847}
 848
 849/*
 850 * Create the kmalloc array. Some of the regular kmalloc arrays
 851 * may already have been created because they were needed to
 852 * enable allocations for slab creation.
 853 */
 854void __init create_kmalloc_caches(slab_flags_t flags)
 855{
 856        int i;
 857        enum kmalloc_cache_type type;
 858
 859        for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) {
 860                for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 861                        if (!kmalloc_caches[type][i])
 862                                new_kmalloc_cache(i, type, flags);
 863
 864                        /*
 865                         * Caches that are not of the two-to-the-power-of size.
 866                         * These have to be created immediately after the
 867                         * earlier power of two caches
 868                         */
 869                        if (KMALLOC_MIN_SIZE <= 32 && i == 6 &&
 870                                        !kmalloc_caches[type][1])
 871                                new_kmalloc_cache(1, type, flags);
 872                        if (KMALLOC_MIN_SIZE <= 64 && i == 7 &&
 873                                        !kmalloc_caches[type][2])
 874                                new_kmalloc_cache(2, type, flags);
 875                }
 876        }
 877
 878        /* Kmalloc array is now usable */
 879        slab_state = UP;
 880
 881#ifdef CONFIG_ZONE_DMA
 882        for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
 883                struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];
 884
 885                if (s) {
 886                        kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(
 887                                kmalloc_info[i].name[KMALLOC_DMA],
 888                                kmalloc_info[i].size,
 889                                SLAB_CACHE_DMA | flags, 0,
 890                                kmalloc_info[i].size);
 891                }
 892        }
 893#endif
 894}
 895#endif /* !CONFIG_SLOB */
 896
 897gfp_t kmalloc_fix_flags(gfp_t flags)
 898{
 899        gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
 900
 901        flags &= ~GFP_SLAB_BUG_MASK;
 902        pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
 903                        invalid_mask, &invalid_mask, flags, &flags);
 904        dump_stack();
 905
 906        return flags;
 907}
 908
 909/*
 910 * To avoid unnecessary overhead, we pass through large allocation requests
 911 * directly to the page allocator. We use __GFP_COMP, because we will need to
 912 * know the allocation order to free the pages properly in kfree.
 913 */
 914void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
 915{
 916        void *ret = NULL;
 917        struct page *page;
 918
 919        if (unlikely(flags & GFP_SLAB_BUG_MASK))
 920                flags = kmalloc_fix_flags(flags);
 921
 922        flags |= __GFP_COMP;
 923        page = alloc_pages(flags, order);
 924        if (likely(page)) {
 925                ret = page_address(page);
 926                mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B,
 927                                      PAGE_SIZE << order);
 928        }
 929        ret = kasan_kmalloc_large(ret, size, flags);
 930        /* As ret might get tagged, call kmemleak hook after KASAN. */
 931        kmemleak_alloc(ret, size, 1, flags);
 932        return ret;
 933}
 934EXPORT_SYMBOL(kmalloc_order);
 935
 936#ifdef CONFIG_TRACING
 937void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
 938{
 939        void *ret = kmalloc_order(size, flags, order);
 940        trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
 941        return ret;
 942}
 943EXPORT_SYMBOL(kmalloc_order_trace);
 944#endif
 945
 946#ifdef CONFIG_SLAB_FREELIST_RANDOM
 947/* Randomize a generic freelist */
 948static void freelist_randomize(struct rnd_state *state, unsigned int *list,
 949                               unsigned int count)
 950{
 951        unsigned int rand;
 952        unsigned int i;
 953
 954        for (i = 0; i < count; i++)
 955                list[i] = i;
 956
 957        /* Fisher-Yates shuffle */
 958        for (i = count - 1; i > 0; i--) {
 959                rand = prandom_u32_state(state);
 960                rand %= (i + 1);
 961                swap(list[i], list[rand]);
 962        }
 963}
 964
 965/* Create a random sequence per cache */
 966int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
 967                                    gfp_t gfp)
 968{
 969        struct rnd_state state;
 970
 971        if (count < 2 || cachep->random_seq)
 972                return 0;
 973
 974        cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
 975        if (!cachep->random_seq)
 976                return -ENOMEM;
 977
 978        /* Get best entropy at this stage of boot */
 979        prandom_seed_state(&state, get_random_long());
 980
 981        freelist_randomize(&state, cachep->random_seq, count);
 982        return 0;
 983}
 984
 985/* Destroy the per-cache random freelist sequence */
 986void cache_random_seq_destroy(struct kmem_cache *cachep)
 987{
 988        kfree(cachep->random_seq);
 989        cachep->random_seq = NULL;
 990}
 991#endif /* CONFIG_SLAB_FREELIST_RANDOM */
 992
 993#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
 994#ifdef CONFIG_SLAB
 995#define SLABINFO_RIGHTS (0600)
 996#else
 997#define SLABINFO_RIGHTS (0400)
 998#endif
 999
1000static void print_slabinfo_header(struct seq_file *m)
1001{
1002        /*
1003         * Output format version, so at least we can change it
1004         * without _too_ many complaints.
1005         */
1006#ifdef CONFIG_DEBUG_SLAB
1007        seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
1008#else
1009        seq_puts(m, "slabinfo - version: 2.1\n");
1010#endif
1011        seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1012        seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1013        seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1014#ifdef CONFIG_DEBUG_SLAB
1015        seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1016        seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1017#endif
1018        seq_putc(m, '\n');
1019}
1020
1021void *slab_start(struct seq_file *m, loff_t *pos)
1022{
1023        mutex_lock(&slab_mutex);
1024        return seq_list_start(&slab_caches, *pos);
1025}
1026
1027void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1028{
1029        return seq_list_next(p, &slab_caches, pos);
1030}
1031
1032void slab_stop(struct seq_file *m, void *p)
1033{
1034        mutex_unlock(&slab_mutex);
1035}
1036
1037static void cache_show(struct kmem_cache *s, struct seq_file *m)
1038{
1039        struct slabinfo sinfo;
1040
1041        memset(&sinfo, 0, sizeof(sinfo));
1042        get_slabinfo(s, &sinfo);
1043
1044        seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1045                   s->name, sinfo.active_objs, sinfo.num_objs, s->size,
1046                   sinfo.objects_per_slab, (1 << sinfo.cache_order));
1047
1048        seq_printf(m, " : tunables %4u %4u %4u",
1049                   sinfo.limit, sinfo.batchcount, sinfo.shared);
1050        seq_printf(m, " : slabdata %6lu %6lu %6lu",
1051                   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1052        slabinfo_show_stats(m, s);
1053        seq_putc(m, '\n');
1054}
1055
1056static int slab_show(struct seq_file *m, void *p)
1057{
1058        struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1059
1060        if (p == slab_caches.next)
1061                print_slabinfo_header(m);
1062        cache_show(s, m);
1063        return 0;
1064}
1065
1066void dump_unreclaimable_slab(void)
1067{
1068        struct kmem_cache *s;
1069        struct slabinfo sinfo;
1070
1071        /*
1072         * Here acquiring slab_mutex is risky since we don't prefer to get
1073         * sleep in oom path. But, without mutex hold, it may introduce a
1074         * risk of crash.
1075         * Use mutex_trylock to protect the list traverse, dump nothing
1076         * without acquiring the mutex.
1077         */
1078        if (!mutex_trylock(&slab_mutex)) {
1079                pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1080                return;
1081        }
1082
1083        pr_info("Unreclaimable slab info:\n");
1084        pr_info("Name                      Used          Total\n");
1085
1086        list_for_each_entry(s, &slab_caches, list) {
1087                if (s->flags & SLAB_RECLAIM_ACCOUNT)
1088                        continue;
1089
1090                get_slabinfo(s, &sinfo);
1091
1092                if (sinfo.num_objs > 0)
1093                        pr_info("%-17s %10luKB %10luKB\n", s->name,
1094                                (sinfo.active_objs * s->size) / 1024,
1095                                (sinfo.num_objs * s->size) / 1024);
1096        }
1097        mutex_unlock(&slab_mutex);
1098}
1099
1100#if defined(CONFIG_MEMCG_KMEM)
1101int memcg_slab_show(struct seq_file *m, void *p)
1102{
1103        /*
1104         * Deprecated.
1105         * Please, take a look at tools/cgroup/slabinfo.py .
1106         */
1107        return 0;
1108}
1109#endif
1110
1111/*
1112 * slabinfo_op - iterator that generates /proc/slabinfo
1113 *
1114 * Output layout:
1115 * cache-name
1116 * num-active-objs
1117 * total-objs
1118 * object size
1119 * num-active-slabs
1120 * total-slabs
1121 * num-pages-per-slab
1122 * + further values on SMP and with statistics enabled
1123 */
1124static const struct seq_operations slabinfo_op = {
1125        .start = slab_start,
1126        .next = slab_next,
1127        .stop = slab_stop,
1128        .show = slab_show,
1129};
1130
1131static int slabinfo_open(struct inode *inode, struct file *file)
1132{
1133        return seq_open(file, &slabinfo_op);
1134}
1135
1136static const struct proc_ops slabinfo_proc_ops = {
1137        .proc_flags     = PROC_ENTRY_PERMANENT,
1138        .proc_open      = slabinfo_open,
1139        .proc_read      = seq_read,
1140        .proc_write     = slabinfo_write,
1141        .proc_lseek     = seq_lseek,
1142        .proc_release   = seq_release,
1143};
1144
1145static int __init slab_proc_init(void)
1146{
1147        proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
1148        return 0;
1149}
1150module_init(slab_proc_init);
1151
1152#endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
1153
1154static __always_inline void *__do_krealloc(const void *p, size_t new_size,
1155                                           gfp_t flags)
1156{
1157        void *ret;
1158        size_t ks;
1159
1160        /* Don't use instrumented ksize to allow precise KASAN poisoning. */
1161        if (likely(!ZERO_OR_NULL_PTR(p))) {
1162                if (!kasan_check_byte(p))
1163                        return NULL;
1164                ks = kfence_ksize(p) ?: __ksize(p);
1165        } else
1166                ks = 0;
1167
1168        /* If the object still fits, repoison it precisely. */
1169        if (ks >= new_size) {
1170                p = kasan_krealloc((void *)p, new_size, flags);
1171                return (void *)p;
1172        }
1173
1174        ret = kmalloc_track_caller(new_size, flags);
1175        if (ret && p) {
1176                /* Disable KASAN checks as the object's redzone is accessed. */
1177                kasan_disable_current();
1178                memcpy(ret, kasan_reset_tag(p), ks);
1179                kasan_enable_current();
1180        }
1181
1182        return ret;
1183}
1184
1185/**
1186 * krealloc - reallocate memory. The contents will remain unchanged.
1187 * @p: object to reallocate memory for.
1188 * @new_size: how many bytes of memory are required.
1189 * @flags: the type of memory to allocate.
1190 *
1191 * The contents of the object pointed to are preserved up to the
1192 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored).
1193 * If @p is %NULL, krealloc() behaves exactly like kmalloc().  If @new_size
1194 * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1195 *
1196 * Return: pointer to the allocated memory or %NULL in case of error
1197 */
1198void *krealloc(const void *p, size_t new_size, gfp_t flags)
1199{
1200        void *ret;
1201
1202        if (unlikely(!new_size)) {
1203                kfree(p);
1204                return ZERO_SIZE_PTR;
1205        }
1206
1207        ret = __do_krealloc(p, new_size, flags);
1208        if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
1209                kfree(p);
1210
1211        return ret;
1212}
1213EXPORT_SYMBOL(krealloc);
1214
1215/**
1216 * kfree_sensitive - Clear sensitive information in memory before freeing
1217 * @p: object to free memory of
1218 *
1219 * The memory of the object @p points to is zeroed before freed.
1220 * If @p is %NULL, kfree_sensitive() does nothing.
1221 *
1222 * Note: this function zeroes the whole allocated buffer which can be a good
1223 * deal bigger than the requested buffer size passed to kmalloc(). So be
1224 * careful when using this function in performance sensitive code.
1225 */
1226void kfree_sensitive(const void *p)
1227{
1228        size_t ks;
1229        void *mem = (void *)p;
1230
1231        ks = ksize(mem);
1232        if (ks)
1233                memzero_explicit(mem, ks);
1234        kfree(mem);
1235}
1236EXPORT_SYMBOL(kfree_sensitive);
1237
1238/**
1239 * ksize - get the actual amount of memory allocated for a given object
1240 * @objp: Pointer to the object
1241 *
1242 * kmalloc may internally round up allocations and return more memory
1243 * than requested. ksize() can be used to determine the actual amount of
1244 * memory allocated. The caller may use this additional memory, even though
1245 * a smaller amount of memory was initially specified with the kmalloc call.
1246 * The caller must guarantee that objp points to a valid object previously
1247 * allocated with either kmalloc() or kmem_cache_alloc(). The object
1248 * must not be freed during the duration of the call.
1249 *
1250 * Return: size of the actual memory used by @objp in bytes
1251 */
1252size_t ksize(const void *objp)
1253{
1254        size_t size;
1255
1256        /*
1257         * We need to first check that the pointer to the object is valid, and
1258         * only then unpoison the memory. The report printed from ksize() is
1259         * more useful, then when it's printed later when the behaviour could
1260         * be undefined due to a potential use-after-free or double-free.
1261         *
1262         * We use kasan_check_byte(), which is supported for the hardware
1263         * tag-based KASAN mode, unlike kasan_check_read/write().
1264         *
1265         * If the pointed to memory is invalid, we return 0 to avoid users of
1266         * ksize() writing to and potentially corrupting the memory region.
1267         *
1268         * We want to perform the check before __ksize(), to avoid potentially
1269         * crashing in __ksize() due to accessing invalid metadata.
1270         */
1271        if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
1272                return 0;
1273
1274        size = kfence_ksize(objp) ?: __ksize(objp);
1275        /*
1276         * We assume that ksize callers could use whole allocated area,
1277         * so we need to unpoison this area.
1278         */
1279        kasan_unpoison_range(objp, size);
1280        return size;
1281}
1282EXPORT_SYMBOL(ksize);
1283
1284/* Tracepoints definitions. */
1285EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1286EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1287EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
1288EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
1289EXPORT_TRACEPOINT_SYMBOL(kfree);
1290EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1291
1292int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
1293{
1294        if (__should_failslab(s, gfpflags))
1295                return -ENOMEM;
1296        return 0;
1297}
1298ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
1299