xref: /linux/mm/slab_common.c (revision 3ea5eb68b9d624935108b5e696859304edfac202)
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/dma-mapping.h>
21 #include <linux/swiotlb.h>
22 #include <linux/proc_fs.h>
23 #include <linux/debugfs.h>
24 #include <linux/kmemleak.h>
25 #include <linux/kasan.h>
26 #include <asm/cacheflush.h>
27 #include <asm/tlbflush.h>
28 #include <asm/page.h>
29 #include <linux/memcontrol.h>
30 #include <linux/stackdepot.h>
31 
32 #include "internal.h"
33 #include "slab.h"
34 
35 #define CREATE_TRACE_POINTS
36 #include <trace/events/kmem.h>
37 
38 enum slab_state slab_state;
39 LIST_HEAD(slab_caches);
40 DEFINE_MUTEX(slab_mutex);
41 struct kmem_cache *kmem_cache;
42 
43 /*
44  * Set of flags that will prevent slab merging
45  */
46 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
47 		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
48 		SLAB_FAILSLAB | SLAB_NO_MERGE)
49 
50 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
51 			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
52 
53 /*
54  * Merge control. If this is set then no merging of slab caches will occur.
55  */
56 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
57 
58 static int __init setup_slab_nomerge(char *str)
59 {
60 	slab_nomerge = true;
61 	return 1;
62 }
63 
64 static int __init setup_slab_merge(char *str)
65 {
66 	slab_nomerge = false;
67 	return 1;
68 }
69 
70 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
71 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
72 
73 __setup("slab_nomerge", setup_slab_nomerge);
74 __setup("slab_merge", setup_slab_merge);
75 
76 /*
77  * Determine the size of a slab object
78  */
79 unsigned int kmem_cache_size(struct kmem_cache *s)
80 {
81 	return s->object_size;
82 }
83 EXPORT_SYMBOL(kmem_cache_size);
84 
85 #ifdef CONFIG_DEBUG_VM
86 
87 static bool kmem_cache_is_duplicate_name(const char *name)
88 {
89 	struct kmem_cache *s;
90 
91 	list_for_each_entry(s, &slab_caches, list) {
92 		if (!strcmp(s->name, name))
93 			return true;
94 	}
95 
96 	return false;
97 }
98 
99 static int kmem_cache_sanity_check(const char *name, unsigned int size)
100 {
101 	if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
102 		pr_err("kmem_cache_create(%s) integrity check failed\n", name);
103 		return -EINVAL;
104 	}
105 
106 	/* Duplicate names will confuse slabtop, et al */
107 	WARN(kmem_cache_is_duplicate_name(name),
108 			"kmem_cache of name '%s' already exists\n", name);
109 
110 	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
111 	return 0;
112 }
113 #else
114 static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
115 {
116 	return 0;
117 }
118 #endif
119 
120 /*
121  * Figure out what the alignment of the objects will be given a set of
122  * flags, a user specified alignment and the size of the objects.
123  */
124 static unsigned int calculate_alignment(slab_flags_t flags,
125 		unsigned int align, unsigned int size)
126 {
127 	/*
128 	 * If the user wants hardware cache aligned objects then follow that
129 	 * suggestion if the object is sufficiently large.
130 	 *
131 	 * The hardware cache alignment cannot override the specified
132 	 * alignment though. If that is greater then use it.
133 	 */
134 	if (flags & SLAB_HWCACHE_ALIGN) {
135 		unsigned int ralign;
136 
137 		ralign = cache_line_size();
138 		while (size <= ralign / 2)
139 			ralign /= 2;
140 		align = max(align, ralign);
141 	}
142 
143 	align = max(align, arch_slab_minalign());
144 
145 	return ALIGN(align, sizeof(void *));
146 }
147 
148 /*
149  * Find a mergeable slab cache
150  */
151 int slab_unmergeable(struct kmem_cache *s)
152 {
153 	if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
154 		return 1;
155 
156 	if (s->ctor)
157 		return 1;
158 
159 #ifdef CONFIG_HARDENED_USERCOPY
160 	if (s->usersize)
161 		return 1;
162 #endif
163 
164 	/*
165 	 * We may have set a slab to be unmergeable during bootstrap.
166 	 */
167 	if (s->refcount < 0)
168 		return 1;
169 
170 	return 0;
171 }
172 
173 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
174 		slab_flags_t flags, const char *name, void (*ctor)(void *))
175 {
176 	struct kmem_cache *s;
177 
178 	if (slab_nomerge)
179 		return NULL;
180 
181 	if (ctor)
182 		return NULL;
183 
184 	flags = kmem_cache_flags(flags, name);
185 
186 	if (flags & SLAB_NEVER_MERGE)
187 		return NULL;
188 
189 	size = ALIGN(size, sizeof(void *));
190 	align = calculate_alignment(flags, align, size);
191 	size = ALIGN(size, align);
192 
193 	list_for_each_entry_reverse(s, &slab_caches, list) {
194 		if (slab_unmergeable(s))
195 			continue;
196 
197 		if (size > s->size)
198 			continue;
199 
200 		if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
201 			continue;
202 		/*
203 		 * Check if alignment is compatible.
204 		 * Courtesy of Adrian Drzewiecki
205 		 */
206 		if ((s->size & ~(align - 1)) != s->size)
207 			continue;
208 
209 		if (s->size - size >= sizeof(void *))
210 			continue;
211 
212 		return s;
213 	}
214 	return NULL;
215 }
216 
217 static struct kmem_cache *create_cache(const char *name,
218 				       unsigned int object_size,
219 				       struct kmem_cache_args *args,
220 				       slab_flags_t flags)
221 {
222 	struct kmem_cache *s;
223 	int err;
224 
225 	if (WARN_ON(args->useroffset + args->usersize > object_size))
226 		args->useroffset = args->usersize = 0;
227 
228 	/* If a custom freelist pointer is requested make sure it's sane. */
229 	err = -EINVAL;
230 	if (args->use_freeptr_offset &&
231 	    (args->freeptr_offset >= object_size ||
232 	     !(flags & SLAB_TYPESAFE_BY_RCU) ||
233 	     !IS_ALIGNED(args->freeptr_offset, sizeof(freeptr_t))))
234 		goto out;
235 
236 	err = -ENOMEM;
237 	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
238 	if (!s)
239 		goto out;
240 	err = do_kmem_cache_create(s, name, object_size, args, flags);
241 	if (err)
242 		goto out_free_cache;
243 
244 	s->refcount = 1;
245 	list_add(&s->list, &slab_caches);
246 	return s;
247 
248 out_free_cache:
249 	kmem_cache_free(kmem_cache, s);
250 out:
251 	return ERR_PTR(err);
252 }
253 
254 /**
255  * __kmem_cache_create_args - Create a kmem cache.
256  * @name: A string which is used in /proc/slabinfo to identify this cache.
257  * @object_size: The size of objects to be created in this cache.
258  * @args: Additional arguments for the cache creation (see
259  *        &struct kmem_cache_args).
260  * @flags: See %SLAB_* flags for an explanation of individual @flags.
261  *
262  * Not to be called directly, use the kmem_cache_create() wrapper with the same
263  * parameters.
264  *
265  * Context: Cannot be called within a interrupt, but can be interrupted.
266  *
267  * Return: a pointer to the cache on success, NULL on failure.
268  */
269 struct kmem_cache *__kmem_cache_create_args(const char *name,
270 					    unsigned int object_size,
271 					    struct kmem_cache_args *args,
272 					    slab_flags_t flags)
273 {
274 	struct kmem_cache *s = NULL;
275 	const char *cache_name;
276 	int err;
277 
278 #ifdef CONFIG_SLUB_DEBUG
279 	/*
280 	 * If no slab_debug was enabled globally, the static key is not yet
281 	 * enabled by setup_slub_debug(). Enable it if the cache is being
282 	 * created with any of the debugging flags passed explicitly.
283 	 * It's also possible that this is the first cache created with
284 	 * SLAB_STORE_USER and we should init stack_depot for it.
285 	 */
286 	if (flags & SLAB_DEBUG_FLAGS)
287 		static_branch_enable(&slub_debug_enabled);
288 	if (flags & SLAB_STORE_USER)
289 		stack_depot_init();
290 #endif
291 
292 	mutex_lock(&slab_mutex);
293 
294 	err = kmem_cache_sanity_check(name, object_size);
295 	if (err) {
296 		goto out_unlock;
297 	}
298 
299 	/* Refuse requests with allocator specific flags */
300 	if (flags & ~SLAB_FLAGS_PERMITTED) {
301 		err = -EINVAL;
302 		goto out_unlock;
303 	}
304 
305 	/*
306 	 * Some allocators will constraint the set of valid flags to a subset
307 	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
308 	 * case, and we'll just provide them with a sanitized version of the
309 	 * passed flags.
310 	 */
311 	flags &= CACHE_CREATE_MASK;
312 
313 	/* Fail closed on bad usersize of useroffset values. */
314 	if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
315 	    WARN_ON(!args->usersize && args->useroffset) ||
316 	    WARN_ON(object_size < args->usersize ||
317 		    object_size - args->usersize < args->useroffset))
318 		args->usersize = args->useroffset = 0;
319 
320 	if (!args->usersize)
321 		s = __kmem_cache_alias(name, object_size, args->align, flags,
322 				       args->ctor);
323 	if (s)
324 		goto out_unlock;
325 
326 	cache_name = kstrdup_const(name, GFP_KERNEL);
327 	if (!cache_name) {
328 		err = -ENOMEM;
329 		goto out_unlock;
330 	}
331 
332 	args->align = calculate_alignment(flags, args->align, object_size);
333 	s = create_cache(cache_name, object_size, args, flags);
334 	if (IS_ERR(s)) {
335 		err = PTR_ERR(s);
336 		kfree_const(cache_name);
337 	}
338 
339 out_unlock:
340 	mutex_unlock(&slab_mutex);
341 
342 	if (err) {
343 		if (flags & SLAB_PANIC)
344 			panic("%s: Failed to create slab '%s'. Error %d\n",
345 				__func__, name, err);
346 		else {
347 			pr_warn("%s(%s) failed with error %d\n",
348 				__func__, name, err);
349 			dump_stack();
350 		}
351 		return NULL;
352 	}
353 	return s;
354 }
355 EXPORT_SYMBOL(__kmem_cache_create_args);
356 
357 static struct kmem_cache *kmem_buckets_cache __ro_after_init;
358 
359 /**
360  * kmem_buckets_create - Create a set of caches that handle dynamic sized
361  *			 allocations via kmem_buckets_alloc()
362  * @name: A prefix string which is used in /proc/slabinfo to identify this
363  *	  cache. The individual caches with have their sizes as the suffix.
364  * @flags: SLAB flags (see kmem_cache_create() for details).
365  * @useroffset: Starting offset within an allocation that may be copied
366  *		to/from userspace.
367  * @usersize: How many bytes, starting at @useroffset, may be copied
368  *		to/from userspace.
369  * @ctor: A constructor for the objects, run when new allocations are made.
370  *
371  * Cannot be called within an interrupt, but can be interrupted.
372  *
373  * Return: a pointer to the cache on success, NULL on failure. When
374  * CONFIG_SLAB_BUCKETS is not enabled, ZERO_SIZE_PTR is returned, and
375  * subsequent calls to kmem_buckets_alloc() will fall back to kmalloc().
376  * (i.e. callers only need to check for NULL on failure.)
377  */
378 kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags,
379 				  unsigned int useroffset,
380 				  unsigned int usersize,
381 				  void (*ctor)(void *))
382 {
383 	kmem_buckets *b;
384 	int idx;
385 
386 	/*
387 	 * When the separate buckets API is not built in, just return
388 	 * a non-NULL value for the kmem_buckets pointer, which will be
389 	 * unused when performing allocations.
390 	 */
391 	if (!IS_ENABLED(CONFIG_SLAB_BUCKETS))
392 		return ZERO_SIZE_PTR;
393 
394 	if (WARN_ON(!kmem_buckets_cache))
395 		return NULL;
396 
397 	b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO);
398 	if (WARN_ON(!b))
399 		return NULL;
400 
401 	flags |= SLAB_NO_MERGE;
402 
403 	for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
404 		char *short_size, *cache_name;
405 		unsigned int cache_useroffset, cache_usersize;
406 		unsigned int size;
407 
408 		if (!kmalloc_caches[KMALLOC_NORMAL][idx])
409 			continue;
410 
411 		size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size;
412 		if (!size)
413 			continue;
414 
415 		short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name, '-');
416 		if (WARN_ON(!short_size))
417 			goto fail;
418 
419 		cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size + 1);
420 		if (WARN_ON(!cache_name))
421 			goto fail;
422 
423 		if (useroffset >= size) {
424 			cache_useroffset = 0;
425 			cache_usersize = 0;
426 		} else {
427 			cache_useroffset = useroffset;
428 			cache_usersize = min(size - cache_useroffset, usersize);
429 		}
430 		(*b)[idx] = kmem_cache_create_usercopy(cache_name, size,
431 					0, flags, cache_useroffset,
432 					cache_usersize, ctor);
433 		kfree(cache_name);
434 		if (WARN_ON(!(*b)[idx]))
435 			goto fail;
436 	}
437 
438 	return b;
439 
440 fail:
441 	for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++)
442 		kmem_cache_destroy((*b)[idx]);
443 	kmem_cache_free(kmem_buckets_cache, b);
444 
445 	return NULL;
446 }
447 EXPORT_SYMBOL(kmem_buckets_create);
448 
449 /*
450  * For a given kmem_cache, kmem_cache_destroy() should only be called
451  * once or there will be a use-after-free problem. The actual deletion
452  * and release of the kobject does not need slab_mutex or cpu_hotplug_lock
453  * protection. So they are now done without holding those locks.
454  */
455 static void kmem_cache_release(struct kmem_cache *s)
456 {
457 	kfence_shutdown_cache(s);
458 	if (__is_defined(SLAB_SUPPORTS_SYSFS) && slab_state >= FULL)
459 		sysfs_slab_release(s);
460 	else
461 		slab_kmem_cache_release(s);
462 }
463 
464 void slab_kmem_cache_release(struct kmem_cache *s)
465 {
466 	__kmem_cache_release(s);
467 	kfree_const(s->name);
468 	kmem_cache_free(kmem_cache, s);
469 }
470 
471 void kmem_cache_destroy(struct kmem_cache *s)
472 {
473 	int err;
474 
475 	if (unlikely(!s) || !kasan_check_byte(s))
476 		return;
477 
478 	/* in-flight kfree_rcu()'s may include objects from our cache */
479 	kvfree_rcu_barrier();
480 
481 	if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) &&
482 	    (s->flags & SLAB_TYPESAFE_BY_RCU)) {
483 		/*
484 		 * Under CONFIG_SLUB_RCU_DEBUG, when objects in a
485 		 * SLAB_TYPESAFE_BY_RCU slab are freed, SLUB will internally
486 		 * defer their freeing with call_rcu().
487 		 * Wait for such call_rcu() invocations here before actually
488 		 * destroying the cache.
489 		 *
490 		 * It doesn't matter that we haven't looked at the slab refcount
491 		 * yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so
492 		 * the refcount should be 1 here.
493 		 */
494 		rcu_barrier();
495 	}
496 
497 	cpus_read_lock();
498 	mutex_lock(&slab_mutex);
499 
500 	s->refcount--;
501 	if (s->refcount) {
502 		mutex_unlock(&slab_mutex);
503 		cpus_read_unlock();
504 		return;
505 	}
506 
507 	/* free asan quarantined objects */
508 	kasan_cache_shutdown(s);
509 
510 	err = __kmem_cache_shutdown(s);
511 	WARN(err, "%s %s: Slab cache still has objects when called from %pS",
512 	     __func__, s->name, (void *)_RET_IP_);
513 
514 	list_del(&s->list);
515 
516 	mutex_unlock(&slab_mutex);
517 	cpus_read_unlock();
518 
519 	if (slab_state >= FULL)
520 		sysfs_slab_unlink(s);
521 	debugfs_slab_release(s);
522 
523 	if (err)
524 		return;
525 
526 	if (s->flags & SLAB_TYPESAFE_BY_RCU)
527 		rcu_barrier();
528 
529 	kmem_cache_release(s);
530 }
531 EXPORT_SYMBOL(kmem_cache_destroy);
532 
533 /**
534  * kmem_cache_shrink - Shrink a cache.
535  * @cachep: The cache to shrink.
536  *
537  * Releases as many slabs as possible for a cache.
538  * To help debugging, a zero exit status indicates all slabs were released.
539  *
540  * Return: %0 if all slabs were released, non-zero otherwise
541  */
542 int kmem_cache_shrink(struct kmem_cache *cachep)
543 {
544 	kasan_cache_shrink(cachep);
545 
546 	return __kmem_cache_shrink(cachep);
547 }
548 EXPORT_SYMBOL(kmem_cache_shrink);
549 
550 bool slab_is_available(void)
551 {
552 	return slab_state >= UP;
553 }
554 
555 #ifdef CONFIG_PRINTK
556 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
557 {
558 	if (__kfence_obj_info(kpp, object, slab))
559 		return;
560 	__kmem_obj_info(kpp, object, slab);
561 }
562 
563 /**
564  * kmem_dump_obj - Print available slab provenance information
565  * @object: slab object for which to find provenance information.
566  *
567  * This function uses pr_cont(), so that the caller is expected to have
568  * printed out whatever preamble is appropriate.  The provenance information
569  * depends on the type of object and on how much debugging is enabled.
570  * For a slab-cache object, the fact that it is a slab object is printed,
571  * and, if available, the slab name, return address, and stack trace from
572  * the allocation and last free path of that object.
573  *
574  * Return: %true if the pointer is to a not-yet-freed object from
575  * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
576  * is to an already-freed object, and %false otherwise.
577  */
578 bool kmem_dump_obj(void *object)
579 {
580 	char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
581 	int i;
582 	struct slab *slab;
583 	unsigned long ptroffset;
584 	struct kmem_obj_info kp = { };
585 
586 	/* Some arches consider ZERO_SIZE_PTR to be a valid address. */
587 	if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
588 		return false;
589 	slab = virt_to_slab(object);
590 	if (!slab)
591 		return false;
592 
593 	kmem_obj_info(&kp, object, slab);
594 	if (kp.kp_slab_cache)
595 		pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
596 	else
597 		pr_cont(" slab%s", cp);
598 	if (is_kfence_address(object))
599 		pr_cont(" (kfence)");
600 	if (kp.kp_objp)
601 		pr_cont(" start %px", kp.kp_objp);
602 	if (kp.kp_data_offset)
603 		pr_cont(" data offset %lu", kp.kp_data_offset);
604 	if (kp.kp_objp) {
605 		ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
606 		pr_cont(" pointer offset %lu", ptroffset);
607 	}
608 	if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
609 		pr_cont(" size %u", kp.kp_slab_cache->object_size);
610 	if (kp.kp_ret)
611 		pr_cont(" allocated at %pS\n", kp.kp_ret);
612 	else
613 		pr_cont("\n");
614 	for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
615 		if (!kp.kp_stack[i])
616 			break;
617 		pr_info("    %pS\n", kp.kp_stack[i]);
618 	}
619 
620 	if (kp.kp_free_stack[0])
621 		pr_cont(" Free path:\n");
622 
623 	for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
624 		if (!kp.kp_free_stack[i])
625 			break;
626 		pr_info("    %pS\n", kp.kp_free_stack[i]);
627 	}
628 
629 	return true;
630 }
631 EXPORT_SYMBOL_GPL(kmem_dump_obj);
632 #endif
633 
634 /* Create a cache during boot when no slab services are available yet */
635 void __init create_boot_cache(struct kmem_cache *s, const char *name,
636 		unsigned int size, slab_flags_t flags,
637 		unsigned int useroffset, unsigned int usersize)
638 {
639 	int err;
640 	unsigned int align = ARCH_KMALLOC_MINALIGN;
641 	struct kmem_cache_args kmem_args = {};
642 
643 	/*
644 	 * kmalloc caches guarantee alignment of at least the largest
645 	 * power-of-two divisor of the size. For power-of-two sizes,
646 	 * it is the size itself.
647 	 */
648 	if (flags & SLAB_KMALLOC)
649 		align = max(align, 1U << (ffs(size) - 1));
650 	kmem_args.align = calculate_alignment(flags, align, size);
651 
652 #ifdef CONFIG_HARDENED_USERCOPY
653 	kmem_args.useroffset = useroffset;
654 	kmem_args.usersize = usersize;
655 #endif
656 
657 	err = do_kmem_cache_create(s, name, size, &kmem_args, flags);
658 
659 	if (err)
660 		panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
661 					name, size, err);
662 
663 	s->refcount = -1;	/* Exempt from merging for now */
664 }
665 
666 static struct kmem_cache *__init create_kmalloc_cache(const char *name,
667 						      unsigned int size,
668 						      slab_flags_t flags)
669 {
670 	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
671 
672 	if (!s)
673 		panic("Out of memory when creating slab %s\n", name);
674 
675 	create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size);
676 	list_add(&s->list, &slab_caches);
677 	s->refcount = 1;
678 	return s;
679 }
680 
681 kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init =
682 { /* initialization for https://llvm.org/pr42570 */ };
683 EXPORT_SYMBOL(kmalloc_caches);
684 
685 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
686 unsigned long random_kmalloc_seed __ro_after_init;
687 EXPORT_SYMBOL(random_kmalloc_seed);
688 #endif
689 
690 /*
691  * Conversion table for small slabs sizes / 8 to the index in the
692  * kmalloc array. This is necessary for slabs < 192 since we have non power
693  * of two cache sizes there. The size of larger slabs can be determined using
694  * fls.
695  */
696 u8 kmalloc_size_index[24] __ro_after_init = {
697 	3,	/* 8 */
698 	4,	/* 16 */
699 	5,	/* 24 */
700 	5,	/* 32 */
701 	6,	/* 40 */
702 	6,	/* 48 */
703 	6,	/* 56 */
704 	6,	/* 64 */
705 	1,	/* 72 */
706 	1,	/* 80 */
707 	1,	/* 88 */
708 	1,	/* 96 */
709 	7,	/* 104 */
710 	7,	/* 112 */
711 	7,	/* 120 */
712 	7,	/* 128 */
713 	2,	/* 136 */
714 	2,	/* 144 */
715 	2,	/* 152 */
716 	2,	/* 160 */
717 	2,	/* 168 */
718 	2,	/* 176 */
719 	2,	/* 184 */
720 	2	/* 192 */
721 };
722 
723 size_t kmalloc_size_roundup(size_t size)
724 {
725 	if (size && size <= KMALLOC_MAX_CACHE_SIZE) {
726 		/*
727 		 * The flags don't matter since size_index is common to all.
728 		 * Neither does the caller for just getting ->object_size.
729 		 */
730 		return kmalloc_slab(size, NULL, GFP_KERNEL, 0)->object_size;
731 	}
732 
733 	/* Above the smaller buckets, size is a multiple of page size. */
734 	if (size && size <= KMALLOC_MAX_SIZE)
735 		return PAGE_SIZE << get_order(size);
736 
737 	/*
738 	 * Return 'size' for 0 - kmalloc() returns ZERO_SIZE_PTR
739 	 * and very large size - kmalloc() may fail.
740 	 */
741 	return size;
742 
743 }
744 EXPORT_SYMBOL(kmalloc_size_roundup);
745 
746 #ifdef CONFIG_ZONE_DMA
747 #define KMALLOC_DMA_NAME(sz)	.name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
748 #else
749 #define KMALLOC_DMA_NAME(sz)
750 #endif
751 
752 #ifdef CONFIG_MEMCG
753 #define KMALLOC_CGROUP_NAME(sz)	.name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
754 #else
755 #define KMALLOC_CGROUP_NAME(sz)
756 #endif
757 
758 #ifndef CONFIG_SLUB_TINY
759 #define KMALLOC_RCL_NAME(sz)	.name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
760 #else
761 #define KMALLOC_RCL_NAME(sz)
762 #endif
763 
764 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
765 #define __KMALLOC_RANDOM_CONCAT(a, b) a ## b
766 #define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz)
767 #define KMA_RAND_1(sz)                  .name[KMALLOC_RANDOM_START +  1] = "kmalloc-rnd-01-" #sz,
768 #define KMA_RAND_2(sz)  KMA_RAND_1(sz)  .name[KMALLOC_RANDOM_START +  2] = "kmalloc-rnd-02-" #sz,
769 #define KMA_RAND_3(sz)  KMA_RAND_2(sz)  .name[KMALLOC_RANDOM_START +  3] = "kmalloc-rnd-03-" #sz,
770 #define KMA_RAND_4(sz)  KMA_RAND_3(sz)  .name[KMALLOC_RANDOM_START +  4] = "kmalloc-rnd-04-" #sz,
771 #define KMA_RAND_5(sz)  KMA_RAND_4(sz)  .name[KMALLOC_RANDOM_START +  5] = "kmalloc-rnd-05-" #sz,
772 #define KMA_RAND_6(sz)  KMA_RAND_5(sz)  .name[KMALLOC_RANDOM_START +  6] = "kmalloc-rnd-06-" #sz,
773 #define KMA_RAND_7(sz)  KMA_RAND_6(sz)  .name[KMALLOC_RANDOM_START +  7] = "kmalloc-rnd-07-" #sz,
774 #define KMA_RAND_8(sz)  KMA_RAND_7(sz)  .name[KMALLOC_RANDOM_START +  8] = "kmalloc-rnd-08-" #sz,
775 #define KMA_RAND_9(sz)  KMA_RAND_8(sz)  .name[KMALLOC_RANDOM_START +  9] = "kmalloc-rnd-09-" #sz,
776 #define KMA_RAND_10(sz) KMA_RAND_9(sz)  .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz,
777 #define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz,
778 #define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz,
779 #define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz,
780 #define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz,
781 #define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz,
782 #else // CONFIG_RANDOM_KMALLOC_CACHES
783 #define KMALLOC_RANDOM_NAME(N, sz)
784 #endif
785 
786 #define INIT_KMALLOC_INFO(__size, __short_size)			\
787 {								\
788 	.name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,	\
789 	KMALLOC_RCL_NAME(__short_size)				\
790 	KMALLOC_CGROUP_NAME(__short_size)			\
791 	KMALLOC_DMA_NAME(__short_size)				\
792 	KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size)	\
793 	.size = __size,						\
794 }
795 
796 /*
797  * kmalloc_info[] is to make slab_debug=,kmalloc-xx option work at boot time.
798  * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
799  * kmalloc-2M.
800  */
801 const struct kmalloc_info_struct kmalloc_info[] __initconst = {
802 	INIT_KMALLOC_INFO(0, 0),
803 	INIT_KMALLOC_INFO(96, 96),
804 	INIT_KMALLOC_INFO(192, 192),
805 	INIT_KMALLOC_INFO(8, 8),
806 	INIT_KMALLOC_INFO(16, 16),
807 	INIT_KMALLOC_INFO(32, 32),
808 	INIT_KMALLOC_INFO(64, 64),
809 	INIT_KMALLOC_INFO(128, 128),
810 	INIT_KMALLOC_INFO(256, 256),
811 	INIT_KMALLOC_INFO(512, 512),
812 	INIT_KMALLOC_INFO(1024, 1k),
813 	INIT_KMALLOC_INFO(2048, 2k),
814 	INIT_KMALLOC_INFO(4096, 4k),
815 	INIT_KMALLOC_INFO(8192, 8k),
816 	INIT_KMALLOC_INFO(16384, 16k),
817 	INIT_KMALLOC_INFO(32768, 32k),
818 	INIT_KMALLOC_INFO(65536, 64k),
819 	INIT_KMALLOC_INFO(131072, 128k),
820 	INIT_KMALLOC_INFO(262144, 256k),
821 	INIT_KMALLOC_INFO(524288, 512k),
822 	INIT_KMALLOC_INFO(1048576, 1M),
823 	INIT_KMALLOC_INFO(2097152, 2M)
824 };
825 
826 /*
827  * Patch up the size_index table if we have strange large alignment
828  * requirements for the kmalloc array. This is only the case for
829  * MIPS it seems. The standard arches will not generate any code here.
830  *
831  * Largest permitted alignment is 256 bytes due to the way we
832  * handle the index determination for the smaller caches.
833  *
834  * Make sure that nothing crazy happens if someone starts tinkering
835  * around with ARCH_KMALLOC_MINALIGN
836  */
837 void __init setup_kmalloc_cache_index_table(void)
838 {
839 	unsigned int i;
840 
841 	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
842 		!is_power_of_2(KMALLOC_MIN_SIZE));
843 
844 	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
845 		unsigned int elem = size_index_elem(i);
846 
847 		if (elem >= ARRAY_SIZE(kmalloc_size_index))
848 			break;
849 		kmalloc_size_index[elem] = KMALLOC_SHIFT_LOW;
850 	}
851 
852 	if (KMALLOC_MIN_SIZE >= 64) {
853 		/*
854 		 * The 96 byte sized cache is not used if the alignment
855 		 * is 64 byte.
856 		 */
857 		for (i = 64 + 8; i <= 96; i += 8)
858 			kmalloc_size_index[size_index_elem(i)] = 7;
859 
860 	}
861 
862 	if (KMALLOC_MIN_SIZE >= 128) {
863 		/*
864 		 * The 192 byte sized cache is not used if the alignment
865 		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
866 		 * instead.
867 		 */
868 		for (i = 128 + 8; i <= 192; i += 8)
869 			kmalloc_size_index[size_index_elem(i)] = 8;
870 	}
871 }
872 
873 static unsigned int __kmalloc_minalign(void)
874 {
875 	unsigned int minalign = dma_get_cache_alignment();
876 
877 	if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) &&
878 	    is_swiotlb_allocated())
879 		minalign = ARCH_KMALLOC_MINALIGN;
880 
881 	return max(minalign, arch_slab_minalign());
882 }
883 
884 static void __init
885 new_kmalloc_cache(int idx, enum kmalloc_cache_type type)
886 {
887 	slab_flags_t flags = 0;
888 	unsigned int minalign = __kmalloc_minalign();
889 	unsigned int aligned_size = kmalloc_info[idx].size;
890 	int aligned_idx = idx;
891 
892 	if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
893 		flags |= SLAB_RECLAIM_ACCOUNT;
894 	} else if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_CGROUP)) {
895 		if (mem_cgroup_kmem_disabled()) {
896 			kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
897 			return;
898 		}
899 		flags |= SLAB_ACCOUNT;
900 	} else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
901 		flags |= SLAB_CACHE_DMA;
902 	}
903 
904 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
905 	if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END)
906 		flags |= SLAB_NO_MERGE;
907 #endif
908 
909 	/*
910 	 * If CONFIG_MEMCG is enabled, disable cache merging for
911 	 * KMALLOC_NORMAL caches.
912 	 */
913 	if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL))
914 		flags |= SLAB_NO_MERGE;
915 
916 	if (minalign > ARCH_KMALLOC_MINALIGN) {
917 		aligned_size = ALIGN(aligned_size, minalign);
918 		aligned_idx = __kmalloc_index(aligned_size, false);
919 	}
920 
921 	if (!kmalloc_caches[type][aligned_idx])
922 		kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
923 					kmalloc_info[aligned_idx].name[type],
924 					aligned_size, flags);
925 	if (idx != aligned_idx)
926 		kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
927 }
928 
929 /*
930  * Create the kmalloc array. Some of the regular kmalloc arrays
931  * may already have been created because they were needed to
932  * enable allocations for slab creation.
933  */
934 void __init create_kmalloc_caches(void)
935 {
936 	int i;
937 	enum kmalloc_cache_type type;
938 
939 	/*
940 	 * Including KMALLOC_CGROUP if CONFIG_MEMCG defined
941 	 */
942 	for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
943 		/* Caches that are NOT of the two-to-the-power-of size. */
944 		if (KMALLOC_MIN_SIZE <= 32)
945 			new_kmalloc_cache(1, type);
946 		if (KMALLOC_MIN_SIZE <= 64)
947 			new_kmalloc_cache(2, type);
948 
949 		/* Caches that are of the two-to-the-power-of size. */
950 		for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
951 			new_kmalloc_cache(i, type);
952 	}
953 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
954 	random_kmalloc_seed = get_random_u64();
955 #endif
956 
957 	/* Kmalloc array is now usable */
958 	slab_state = UP;
959 
960 	if (IS_ENABLED(CONFIG_SLAB_BUCKETS))
961 		kmem_buckets_cache = kmem_cache_create("kmalloc_buckets",
962 						       sizeof(kmem_buckets),
963 						       0, SLAB_NO_MERGE, NULL);
964 }
965 
966 /**
967  * __ksize -- Report full size of underlying allocation
968  * @object: pointer to the object
969  *
970  * This should only be used internally to query the true size of allocations.
971  * It is not meant to be a way to discover the usable size of an allocation
972  * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
973  * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
974  * and/or FORTIFY_SOURCE.
975  *
976  * Return: size of the actual memory used by @object in bytes
977  */
978 size_t __ksize(const void *object)
979 {
980 	struct folio *folio;
981 
982 	if (unlikely(object == ZERO_SIZE_PTR))
983 		return 0;
984 
985 	folio = virt_to_folio(object);
986 
987 	if (unlikely(!folio_test_slab(folio))) {
988 		if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE))
989 			return 0;
990 		if (WARN_ON(object != folio_address(folio)))
991 			return 0;
992 		return folio_size(folio);
993 	}
994 
995 #ifdef CONFIG_SLUB_DEBUG
996 	skip_orig_size_check(folio_slab(folio)->slab_cache, object);
997 #endif
998 
999 	return slab_ksize(folio_slab(folio)->slab_cache);
1000 }
1001 
1002 gfp_t kmalloc_fix_flags(gfp_t flags)
1003 {
1004 	gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
1005 
1006 	flags &= ~GFP_SLAB_BUG_MASK;
1007 	pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
1008 			invalid_mask, &invalid_mask, flags, &flags);
1009 	dump_stack();
1010 
1011 	return flags;
1012 }
1013 
1014 #ifdef CONFIG_SLAB_FREELIST_RANDOM
1015 /* Randomize a generic freelist */
1016 static void freelist_randomize(unsigned int *list,
1017 			       unsigned int count)
1018 {
1019 	unsigned int rand;
1020 	unsigned int i;
1021 
1022 	for (i = 0; i < count; i++)
1023 		list[i] = i;
1024 
1025 	/* Fisher-Yates shuffle */
1026 	for (i = count - 1; i > 0; i--) {
1027 		rand = get_random_u32_below(i + 1);
1028 		swap(list[i], list[rand]);
1029 	}
1030 }
1031 
1032 /* Create a random sequence per cache */
1033 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1034 				    gfp_t gfp)
1035 {
1036 
1037 	if (count < 2 || cachep->random_seq)
1038 		return 0;
1039 
1040 	cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1041 	if (!cachep->random_seq)
1042 		return -ENOMEM;
1043 
1044 	freelist_randomize(cachep->random_seq, count);
1045 	return 0;
1046 }
1047 
1048 /* Destroy the per-cache random freelist sequence */
1049 void cache_random_seq_destroy(struct kmem_cache *cachep)
1050 {
1051 	kfree(cachep->random_seq);
1052 	cachep->random_seq = NULL;
1053 }
1054 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1055 
1056 #ifdef CONFIG_SLUB_DEBUG
1057 #define SLABINFO_RIGHTS (0400)
1058 
1059 static void print_slabinfo_header(struct seq_file *m)
1060 {
1061 	/*
1062 	 * Output format version, so at least we can change it
1063 	 * without _too_ many complaints.
1064 	 */
1065 	seq_puts(m, "slabinfo - version: 2.1\n");
1066 	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1067 	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1068 	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1069 	seq_putc(m, '\n');
1070 }
1071 
1072 static void *slab_start(struct seq_file *m, loff_t *pos)
1073 {
1074 	mutex_lock(&slab_mutex);
1075 	return seq_list_start(&slab_caches, *pos);
1076 }
1077 
1078 static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1079 {
1080 	return seq_list_next(p, &slab_caches, pos);
1081 }
1082 
1083 static void slab_stop(struct seq_file *m, void *p)
1084 {
1085 	mutex_unlock(&slab_mutex);
1086 }
1087 
1088 static void cache_show(struct kmem_cache *s, struct seq_file *m)
1089 {
1090 	struct slabinfo sinfo;
1091 
1092 	memset(&sinfo, 0, sizeof(sinfo));
1093 	get_slabinfo(s, &sinfo);
1094 
1095 	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1096 		   s->name, sinfo.active_objs, sinfo.num_objs, s->size,
1097 		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
1098 
1099 	seq_printf(m, " : tunables %4u %4u %4u",
1100 		   sinfo.limit, sinfo.batchcount, sinfo.shared);
1101 	seq_printf(m, " : slabdata %6lu %6lu %6lu",
1102 		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1103 	seq_putc(m, '\n');
1104 }
1105 
1106 static int slab_show(struct seq_file *m, void *p)
1107 {
1108 	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1109 
1110 	if (p == slab_caches.next)
1111 		print_slabinfo_header(m);
1112 	cache_show(s, m);
1113 	return 0;
1114 }
1115 
1116 void dump_unreclaimable_slab(void)
1117 {
1118 	struct kmem_cache *s;
1119 	struct slabinfo sinfo;
1120 
1121 	/*
1122 	 * Here acquiring slab_mutex is risky since we don't prefer to get
1123 	 * sleep in oom path. But, without mutex hold, it may introduce a
1124 	 * risk of crash.
1125 	 * Use mutex_trylock to protect the list traverse, dump nothing
1126 	 * without acquiring the mutex.
1127 	 */
1128 	if (!mutex_trylock(&slab_mutex)) {
1129 		pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1130 		return;
1131 	}
1132 
1133 	pr_info("Unreclaimable slab info:\n");
1134 	pr_info("Name                      Used          Total\n");
1135 
1136 	list_for_each_entry(s, &slab_caches, list) {
1137 		if (s->flags & SLAB_RECLAIM_ACCOUNT)
1138 			continue;
1139 
1140 		get_slabinfo(s, &sinfo);
1141 
1142 		if (sinfo.num_objs > 0)
1143 			pr_info("%-17s %10luKB %10luKB\n", s->name,
1144 				(sinfo.active_objs * s->size) / 1024,
1145 				(sinfo.num_objs * s->size) / 1024);
1146 	}
1147 	mutex_unlock(&slab_mutex);
1148 }
1149 
1150 /*
1151  * slabinfo_op - iterator that generates /proc/slabinfo
1152  *
1153  * Output layout:
1154  * cache-name
1155  * num-active-objs
1156  * total-objs
1157  * object size
1158  * num-active-slabs
1159  * total-slabs
1160  * num-pages-per-slab
1161  * + further values on SMP and with statistics enabled
1162  */
1163 static const struct seq_operations slabinfo_op = {
1164 	.start = slab_start,
1165 	.next = slab_next,
1166 	.stop = slab_stop,
1167 	.show = slab_show,
1168 };
1169 
1170 static int slabinfo_open(struct inode *inode, struct file *file)
1171 {
1172 	return seq_open(file, &slabinfo_op);
1173 }
1174 
1175 static const struct proc_ops slabinfo_proc_ops = {
1176 	.proc_flags	= PROC_ENTRY_PERMANENT,
1177 	.proc_open	= slabinfo_open,
1178 	.proc_read	= seq_read,
1179 	.proc_lseek	= seq_lseek,
1180 	.proc_release	= seq_release,
1181 };
1182 
1183 static int __init slab_proc_init(void)
1184 {
1185 	proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
1186 	return 0;
1187 }
1188 module_init(slab_proc_init);
1189 
1190 #endif /* CONFIG_SLUB_DEBUG */
1191 
1192 static __always_inline __realloc_size(2) void *
1193 __do_krealloc(const void *p, size_t new_size, gfp_t flags)
1194 {
1195 	void *ret;
1196 	size_t ks;
1197 
1198 	/* Check for double-free before calling ksize. */
1199 	if (likely(!ZERO_OR_NULL_PTR(p))) {
1200 		if (!kasan_check_byte(p))
1201 			return NULL;
1202 		ks = ksize(p);
1203 	} else
1204 		ks = 0;
1205 
1206 	/* If the object still fits, repoison it precisely. */
1207 	if (ks >= new_size) {
1208 		/* Zero out spare memory. */
1209 		if (want_init_on_alloc(flags)) {
1210 			kasan_disable_current();
1211 			memset((void *)p + new_size, 0, ks - new_size);
1212 			kasan_enable_current();
1213 		}
1214 
1215 		p = kasan_krealloc((void *)p, new_size, flags);
1216 		return (void *)p;
1217 	}
1218 
1219 	ret = kmalloc_node_track_caller_noprof(new_size, flags, NUMA_NO_NODE, _RET_IP_);
1220 	if (ret && p) {
1221 		/* Disable KASAN checks as the object's redzone is accessed. */
1222 		kasan_disable_current();
1223 		memcpy(ret, kasan_reset_tag(p), ks);
1224 		kasan_enable_current();
1225 	}
1226 
1227 	return ret;
1228 }
1229 
1230 /**
1231  * krealloc - reallocate memory. The contents will remain unchanged.
1232  * @p: object to reallocate memory for.
1233  * @new_size: how many bytes of memory are required.
1234  * @flags: the type of memory to allocate.
1235  *
1236  * If @p is %NULL, krealloc() behaves exactly like kmalloc().  If @new_size
1237  * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1238  *
1239  * If __GFP_ZERO logic is requested, callers must ensure that, starting with the
1240  * initial memory allocation, every subsequent call to this API for the same
1241  * memory allocation is flagged with __GFP_ZERO. Otherwise, it is possible that
1242  * __GFP_ZERO is not fully honored by this API.
1243  *
1244  * This is the case, since krealloc() only knows about the bucket size of an
1245  * allocation (but not the exact size it was allocated with) and hence
1246  * implements the following semantics for shrinking and growing buffers with
1247  * __GFP_ZERO.
1248  *
1249  *         new             bucket
1250  * 0       size             size
1251  * |--------|----------------|
1252  * |  keep  |      zero      |
1253  *
1254  * In any case, the contents of the object pointed to are preserved up to the
1255  * lesser of the new and old sizes.
1256  *
1257  * Return: pointer to the allocated memory or %NULL in case of error
1258  */
1259 void *krealloc_noprof(const void *p, size_t new_size, gfp_t flags)
1260 {
1261 	void *ret;
1262 
1263 	if (unlikely(!new_size)) {
1264 		kfree(p);
1265 		return ZERO_SIZE_PTR;
1266 	}
1267 
1268 	ret = __do_krealloc(p, new_size, flags);
1269 	if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
1270 		kfree(p);
1271 
1272 	return ret;
1273 }
1274 EXPORT_SYMBOL(krealloc_noprof);
1275 
1276 /**
1277  * kfree_sensitive - Clear sensitive information in memory before freeing
1278  * @p: object to free memory of
1279  *
1280  * The memory of the object @p points to is zeroed before freed.
1281  * If @p is %NULL, kfree_sensitive() does nothing.
1282  *
1283  * Note: this function zeroes the whole allocated buffer which can be a good
1284  * deal bigger than the requested buffer size passed to kmalloc(). So be
1285  * careful when using this function in performance sensitive code.
1286  */
1287 void kfree_sensitive(const void *p)
1288 {
1289 	size_t ks;
1290 	void *mem = (void *)p;
1291 
1292 	ks = ksize(mem);
1293 	if (ks) {
1294 		kasan_unpoison_range(mem, ks);
1295 		memzero_explicit(mem, ks);
1296 	}
1297 	kfree(mem);
1298 }
1299 EXPORT_SYMBOL(kfree_sensitive);
1300 
1301 size_t ksize(const void *objp)
1302 {
1303 	/*
1304 	 * We need to first check that the pointer to the object is valid.
1305 	 * The KASAN report printed from ksize() is more useful, then when
1306 	 * it's printed later when the behaviour could be undefined due to
1307 	 * a potential use-after-free or double-free.
1308 	 *
1309 	 * We use kasan_check_byte(), which is supported for the hardware
1310 	 * tag-based KASAN mode, unlike kasan_check_read/write().
1311 	 *
1312 	 * If the pointed to memory is invalid, we return 0 to avoid users of
1313 	 * ksize() writing to and potentially corrupting the memory region.
1314 	 *
1315 	 * We want to perform the check before __ksize(), to avoid potentially
1316 	 * crashing in __ksize() due to accessing invalid metadata.
1317 	 */
1318 	if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
1319 		return 0;
1320 
1321 	return kfence_ksize(objp) ?: __ksize(objp);
1322 }
1323 EXPORT_SYMBOL(ksize);
1324 
1325 /* Tracepoints definitions. */
1326 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1327 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1328 EXPORT_TRACEPOINT_SYMBOL(kfree);
1329 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1330 
1331