1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
4  *
5  * (C) SGI 2006, Christoph Lameter
6  * 	Cleaned up and restructured to ease the addition of alternative
7  * 	implementations of SLAB allocators.
8  * (C) Linux Foundation 2008-2013
9  *      Unified interface for all slab allocators
10  */
11 
12 #ifndef _LINUX_SLAB_H
13 #define	_LINUX_SLAB_H
14 
15 #include <linux/cache.h>
16 #include <linux/gfp.h>
17 #include <linux/overflow.h>
18 #include <linux/types.h>
19 #include <linux/workqueue.h>
20 #include <linux/percpu-refcount.h>
21 #include <linux/cleanup.h>
22 #include <linux/hash.h>
23 
24 
25 /*
26  * Flags to pass to kmem_cache_create().
27  * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
28  */
29 /* DEBUG: Perform (expensive) checks on alloc/free */
30 #define SLAB_CONSISTENCY_CHECKS	((slab_flags_t __force)0x00000100U)
31 /* DEBUG: Red zone objs in a cache */
32 #define SLAB_RED_ZONE		((slab_flags_t __force)0x00000400U)
33 /* DEBUG: Poison objects */
34 #define SLAB_POISON		((slab_flags_t __force)0x00000800U)
35 /* Indicate a kmalloc slab */
36 #define SLAB_KMALLOC		((slab_flags_t __force)0x00001000U)
37 /* Align objs on cache lines */
38 #define SLAB_HWCACHE_ALIGN	((slab_flags_t __force)0x00002000U)
39 /* Use GFP_DMA memory */
40 #define SLAB_CACHE_DMA		((slab_flags_t __force)0x00004000U)
41 /* Use GFP_DMA32 memory */
42 #define SLAB_CACHE_DMA32	((slab_flags_t __force)0x00008000U)
43 /* DEBUG: Store the last owner for bug hunting */
44 #define SLAB_STORE_USER		((slab_flags_t __force)0x00010000U)
45 /* Panic if kmem_cache_create() fails */
46 #define SLAB_PANIC		((slab_flags_t __force)0x00040000U)
47 /*
48  * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
49  *
50  * This delays freeing the SLAB page by a grace period, it does _NOT_
51  * delay object freeing. This means that if you do kmem_cache_free()
52  * that memory location is free to be reused at any time. Thus it may
53  * be possible to see another object there in the same RCU grace period.
54  *
55  * This feature only ensures the memory location backing the object
56  * stays valid, the trick to using this is relying on an independent
57  * object validation pass. Something like:
58  *
59  * begin:
60  *  rcu_read_lock();
61  *  obj = lockless_lookup(key);
62  *  if (obj) {
63  *    if (!try_get_ref(obj)) // might fail for free objects
64  *      rcu_read_unlock();
65  *      goto begin;
66  *
67  *    if (obj->key != key) { // not the object we expected
68  *      put_ref(obj);
69  *      rcu_read_unlock();
70  *      goto begin;
71  *    }
72  *  }
73  *  rcu_read_unlock();
74  *
75  * This is useful if we need to approach a kernel structure obliquely,
76  * from its address obtained without the usual locking. We can lock
77  * the structure to stabilize it and check it's still at the given address,
78  * only if we can be sure that the memory has not been meanwhile reused
79  * for some other kind of object (which our subsystem's lock might corrupt).
80  *
81  * rcu_read_lock before reading the address, then rcu_read_unlock after
82  * taking the spinlock within the structure expected at that address.
83  *
84  * Note that it is not possible to acquire a lock within a structure
85  * allocated with SLAB_TYPESAFE_BY_RCU without first acquiring a reference
86  * as described above.  The reason is that SLAB_TYPESAFE_BY_RCU pages
87  * are not zeroed before being given to the slab, which means that any
88  * locks must be initialized after each and every kmem_struct_alloc().
89  * Alternatively, make the ctor passed to kmem_cache_create() initialize
90  * the locks at page-allocation time, as is done in __i915_request_ctor(),
91  * sighand_ctor(), and anon_vma_ctor().  Such a ctor permits readers
92  * to safely acquire those ctor-initialized locks under rcu_read_lock()
93  * protection.
94  *
95  * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
96  */
97 /* Defer freeing slabs to RCU */
98 #define SLAB_TYPESAFE_BY_RCU	((slab_flags_t __force)0x00080000U)
99 /* Spread some memory over cpuset */
100 #define SLAB_MEM_SPREAD		((slab_flags_t __force)0x00100000U)
101 /* Trace allocations and frees */
102 #define SLAB_TRACE		((slab_flags_t __force)0x00200000U)
103 
104 /* Flag to prevent checks on free */
105 #ifdef CONFIG_DEBUG_OBJECTS
106 # define SLAB_DEBUG_OBJECTS	((slab_flags_t __force)0x00400000U)
107 #else
108 # define SLAB_DEBUG_OBJECTS	0
109 #endif
110 
111 /* Avoid kmemleak tracing */
112 #define SLAB_NOLEAKTRACE	((slab_flags_t __force)0x00800000U)
113 
114 /*
115  * Prevent merging with compatible kmem caches. This flag should be used
116  * cautiously. Valid use cases:
117  *
118  * - caches created for self-tests (e.g. kunit)
119  * - general caches created and used by a subsystem, only when a
120  *   (subsystem-specific) debug option is enabled
121  * - performance critical caches, should be very rare and consulted with slab
122  *   maintainers, and not used together with CONFIG_SLUB_TINY
123  */
124 #define SLAB_NO_MERGE		((slab_flags_t __force)0x01000000U)
125 
126 /* Fault injection mark */
127 #ifdef CONFIG_FAILSLAB
128 # define SLAB_FAILSLAB		((slab_flags_t __force)0x02000000U)
129 #else
130 # define SLAB_FAILSLAB		0
131 #endif
132 /* Account to memcg */
133 #ifdef CONFIG_MEMCG_KMEM
134 # define SLAB_ACCOUNT		((slab_flags_t __force)0x04000000U)
135 #else
136 # define SLAB_ACCOUNT		0
137 #endif
138 
139 #ifdef CONFIG_KASAN_GENERIC
140 #define SLAB_KASAN		((slab_flags_t __force)0x08000000U)
141 #else
142 #define SLAB_KASAN		0
143 #endif
144 
145 /*
146  * Ignore user specified debugging flags.
147  * Intended for caches created for self-tests so they have only flags
148  * specified in the code and other flags are ignored.
149  */
150 #define SLAB_NO_USER_FLAGS	((slab_flags_t __force)0x10000000U)
151 
152 #ifdef CONFIG_KFENCE
153 #define SLAB_SKIP_KFENCE	((slab_flags_t __force)0x20000000U)
154 #else
155 #define SLAB_SKIP_KFENCE	0
156 #endif
157 
158 /* The following flags affect the page allocator grouping pages by mobility */
159 /* Objects are reclaimable */
160 #ifndef CONFIG_SLUB_TINY
161 #define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0x00020000U)
162 #else
163 #define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0)
164 #endif
165 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
166 
167 /*
168  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
169  *
170  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
171  *
172  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
173  * Both make kfree a no-op.
174  */
175 #define ZERO_SIZE_PTR ((void *)16)
176 
177 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
178 				(unsigned long)ZERO_SIZE_PTR)
179 
180 #include <linux/kasan.h>
181 
182 struct list_lru;
183 struct mem_cgroup;
184 /*
185  * struct kmem_cache related prototypes
186  */
187 bool slab_is_available(void);
188 
189 struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
190 			unsigned int align, slab_flags_t flags,
191 			void (*ctor)(void *));
192 struct kmem_cache *kmem_cache_create_usercopy(const char *name,
193 			unsigned int size, unsigned int align,
194 			slab_flags_t flags,
195 			unsigned int useroffset, unsigned int usersize,
196 			void (*ctor)(void *));
197 void kmem_cache_destroy(struct kmem_cache *s);
198 int kmem_cache_shrink(struct kmem_cache *s);
199 
200 /*
201  * Please use this macro to create slab caches. Simply specify the
202  * name of the structure and maybe some flags that are listed above.
203  *
204  * The alignment of the struct determines object alignment. If you
205  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
206  * then the objects will be properly aligned in SMP configurations.
207  */
208 #define KMEM_CACHE(__struct, __flags)					\
209 		kmem_cache_create(#__struct, sizeof(struct __struct),	\
210 			__alignof__(struct __struct), (__flags), NULL)
211 
212 /*
213  * To whitelist a single field for copying to/from usercopy, use this
214  * macro instead for KMEM_CACHE() above.
215  */
216 #define KMEM_CACHE_USERCOPY(__struct, __flags, __field)			\
217 		kmem_cache_create_usercopy(#__struct,			\
218 			sizeof(struct __struct),			\
219 			__alignof__(struct __struct), (__flags),	\
220 			offsetof(struct __struct, __field),		\
221 			sizeof_field(struct __struct, __field), NULL)
222 
223 /*
224  * Common kmalloc functions provided by all allocators
225  */
226 void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
227 void kfree(const void *objp);
228 void kfree_sensitive(const void *objp);
229 size_t __ksize(const void *objp);
230 
231 DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
232 
233 /**
234  * ksize - Report actual allocation size of associated object
235  *
236  * @objp: Pointer returned from a prior kmalloc()-family allocation.
237  *
238  * This should not be used for writing beyond the originally requested
239  * allocation size. Either use krealloc() or round up the allocation size
240  * with kmalloc_size_roundup() prior to allocation. If this is used to
241  * access beyond the originally requested allocation size, UBSAN_BOUNDS
242  * and/or FORTIFY_SOURCE may trip, since they only know about the
243  * originally allocated size via the __alloc_size attribute.
244  */
245 size_t ksize(const void *objp);
246 
247 #ifdef CONFIG_PRINTK
248 bool kmem_valid_obj(void *object);
249 void kmem_dump_obj(void *object);
250 #endif
251 
252 /*
253  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
254  * alignment larger than the alignment of a 64-bit integer.
255  * Setting ARCH_DMA_MINALIGN in arch headers allows that.
256  */
257 #ifdef ARCH_HAS_DMA_MINALIGN
258 #if ARCH_DMA_MINALIGN > 8 && !defined(ARCH_KMALLOC_MINALIGN)
259 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
260 #endif
261 #endif
262 
263 #ifndef ARCH_KMALLOC_MINALIGN
264 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
265 #elif ARCH_KMALLOC_MINALIGN > 8
266 #define KMALLOC_MIN_SIZE ARCH_KMALLOC_MINALIGN
267 #define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
268 #endif
269 
270 /*
271  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
272  * Intended for arches that get misalignment faults even for 64 bit integer
273  * aligned buffers.
274  */
275 #ifndef ARCH_SLAB_MINALIGN
276 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
277 #endif
278 
279 /*
280  * Arches can define this function if they want to decide the minimum slab
281  * alignment at runtime. The value returned by the function must be a power
282  * of two and >= ARCH_SLAB_MINALIGN.
283  */
284 #ifndef arch_slab_minalign
arch_slab_minalign(void)285 static inline unsigned int arch_slab_minalign(void)
286 {
287 	return ARCH_SLAB_MINALIGN;
288 }
289 #endif
290 
291 /*
292  * kmem_cache_alloc and friends return pointers aligned to ARCH_SLAB_MINALIGN.
293  * kmalloc and friends return pointers aligned to both ARCH_KMALLOC_MINALIGN
294  * and ARCH_SLAB_MINALIGN, but here we only assume the former alignment.
295  */
296 #define __assume_kmalloc_alignment __assume_aligned(ARCH_KMALLOC_MINALIGN)
297 #define __assume_slab_alignment __assume_aligned(ARCH_SLAB_MINALIGN)
298 #define __assume_page_alignment __assume_aligned(PAGE_SIZE)
299 
300 /*
301  * Kmalloc array related definitions
302  */
303 
304 #ifdef CONFIG_SLAB
305 /*
306  * SLAB and SLUB directly allocates requests fitting in to an order-1 page
307  * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
308  */
309 #define KMALLOC_SHIFT_HIGH	(PAGE_SHIFT + 1)
310 #define KMALLOC_SHIFT_MAX	(MAX_ORDER + PAGE_SHIFT)
311 #ifndef KMALLOC_SHIFT_LOW
312 #define KMALLOC_SHIFT_LOW	5
313 #endif
314 #endif
315 
316 #ifdef CONFIG_SLUB
317 #define KMALLOC_SHIFT_HIGH	(PAGE_SHIFT + 1)
318 #define KMALLOC_SHIFT_MAX	(MAX_ORDER + PAGE_SHIFT)
319 #ifndef KMALLOC_SHIFT_LOW
320 #define KMALLOC_SHIFT_LOW	3
321 #endif
322 #endif
323 
324 /* Maximum allocatable size */
325 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_MAX)
326 /* Maximum size for which we actually use a slab cache */
327 #define KMALLOC_MAX_CACHE_SIZE	(1UL << KMALLOC_SHIFT_HIGH)
328 /* Maximum order allocatable via the slab allocator */
329 #define KMALLOC_MAX_ORDER	(KMALLOC_SHIFT_MAX - PAGE_SHIFT)
330 
331 /*
332  * Kmalloc subsystem.
333  */
334 #ifndef KMALLOC_MIN_SIZE
335 #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
336 #endif
337 
338 /*
339  * This restriction comes from byte sized index implementation.
340  * Page size is normally 2^12 bytes and, in this case, if we want to use
341  * byte sized index which can represent 2^8 entries, the size of the object
342  * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
343  * If minimum size of kmalloc is less than 16, we use it as minimum object
344  * size and give up to use byte sized index.
345  */
346 #define SLAB_OBJ_MIN_SIZE      (KMALLOC_MIN_SIZE < 16 ? \
347                                (KMALLOC_MIN_SIZE) : 16)
348 
349 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
350 #define RANDOM_KMALLOC_CACHES_NR	15 // # of cache copies
351 #else
352 #define RANDOM_KMALLOC_CACHES_NR	0
353 #endif
354 
355 /*
356  * Whenever changing this, take care of that kmalloc_type() and
357  * create_kmalloc_caches() still work as intended.
358  *
359  * KMALLOC_NORMAL can contain only unaccounted objects whereas KMALLOC_CGROUP
360  * is for accounted but unreclaimable and non-dma objects. All the other
361  * kmem caches can have both accounted and unaccounted objects.
362  */
363 enum kmalloc_cache_type {
364 	KMALLOC_NORMAL = 0,
365 #ifndef CONFIG_ZONE_DMA
366 	KMALLOC_DMA = KMALLOC_NORMAL,
367 #endif
368 #ifndef CONFIG_MEMCG_KMEM
369 	KMALLOC_CGROUP = KMALLOC_NORMAL,
370 #endif
371 	KMALLOC_RANDOM_START = KMALLOC_NORMAL,
372 	KMALLOC_RANDOM_END = KMALLOC_RANDOM_START + RANDOM_KMALLOC_CACHES_NR,
373 #ifdef CONFIG_SLUB_TINY
374 	KMALLOC_RECLAIM = KMALLOC_NORMAL,
375 #else
376 	KMALLOC_RECLAIM,
377 #endif
378 #ifdef CONFIG_ZONE_DMA
379 	KMALLOC_DMA,
380 #endif
381 #ifdef CONFIG_MEMCG_KMEM
382 	KMALLOC_CGROUP,
383 #endif
384 	NR_KMALLOC_TYPES
385 };
386 
387 extern struct kmem_cache *
388 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
389 
390 /*
391  * Define gfp bits that should not be set for KMALLOC_NORMAL.
392  */
393 #define KMALLOC_NOT_NORMAL_BITS					\
394 	(__GFP_RECLAIMABLE |					\
395 	(IS_ENABLED(CONFIG_ZONE_DMA)   ? __GFP_DMA : 0) |	\
396 	(IS_ENABLED(CONFIG_MEMCG_KMEM) ? __GFP_ACCOUNT : 0))
397 
398 extern unsigned long random_kmalloc_seed;
399 
kmalloc_type(gfp_t flags,unsigned long caller)400 static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags, unsigned long caller)
401 {
402 	/*
403 	 * The most common case is KMALLOC_NORMAL, so test for it
404 	 * with a single branch for all the relevant flags.
405 	 */
406 	if (likely((flags & KMALLOC_NOT_NORMAL_BITS) == 0))
407 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
408 		/* RANDOM_KMALLOC_CACHES_NR (=15) copies + the KMALLOC_NORMAL */
409 		return KMALLOC_RANDOM_START + hash_64(caller ^ random_kmalloc_seed,
410 						      ilog2(RANDOM_KMALLOC_CACHES_NR + 1));
411 #else
412 		return KMALLOC_NORMAL;
413 #endif
414 
415 	/*
416 	 * At least one of the flags has to be set. Their priorities in
417 	 * decreasing order are:
418 	 *  1) __GFP_DMA
419 	 *  2) __GFP_RECLAIMABLE
420 	 *  3) __GFP_ACCOUNT
421 	 */
422 	if (IS_ENABLED(CONFIG_ZONE_DMA) && (flags & __GFP_DMA))
423 		return KMALLOC_DMA;
424 	if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || (flags & __GFP_RECLAIMABLE))
425 		return KMALLOC_RECLAIM;
426 	else
427 		return KMALLOC_CGROUP;
428 }
429 
430 /*
431  * Figure out which kmalloc slab an allocation of a certain size
432  * belongs to.
433  * 0 = zero alloc
434  * 1 =  65 .. 96 bytes
435  * 2 = 129 .. 192 bytes
436  * n = 2^(n-1)+1 .. 2^n
437  *
438  * Note: __kmalloc_index() is compile-time optimized, and not runtime optimized;
439  * typical usage is via kmalloc_index() and therefore evaluated at compile-time.
440  * Callers where !size_is_constant should only be test modules, where runtime
441  * overheads of __kmalloc_index() can be tolerated.  Also see kmalloc_slab().
442  */
__kmalloc_index(size_t size,bool size_is_constant)443 static __always_inline unsigned int __kmalloc_index(size_t size,
444 						    bool size_is_constant)
445 {
446 	if (!size)
447 		return 0;
448 
449 	if (size <= KMALLOC_MIN_SIZE)
450 		return KMALLOC_SHIFT_LOW;
451 
452 	if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
453 		return 1;
454 	if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
455 		return 2;
456 	if (size <=          8) return 3;
457 	if (size <=         16) return 4;
458 	if (size <=         32) return 5;
459 	if (size <=         64) return 6;
460 	if (size <=        128) return 7;
461 	if (size <=        256) return 8;
462 	if (size <=        512) return 9;
463 	if (size <=       1024) return 10;
464 	if (size <=   2 * 1024) return 11;
465 	if (size <=   4 * 1024) return 12;
466 	if (size <=   8 * 1024) return 13;
467 	if (size <=  16 * 1024) return 14;
468 	if (size <=  32 * 1024) return 15;
469 	if (size <=  64 * 1024) return 16;
470 	if (size <= 128 * 1024) return 17;
471 	if (size <= 256 * 1024) return 18;
472 	if (size <= 512 * 1024) return 19;
473 	if (size <= 1024 * 1024) return 20;
474 	if (size <=  2 * 1024 * 1024) return 21;
475 
476 	if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES) && size_is_constant)
477 		BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
478 	else
479 		BUG();
480 
481 	/* Will never be reached. Needed because the compiler may complain */
482 	return -1;
483 }
484 static_assert(PAGE_SHIFT <= 20);
485 #define kmalloc_index(s) __kmalloc_index(s, true)
486 
487 void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
488 
489 /**
490  * kmem_cache_alloc - Allocate an object
491  * @cachep: The cache to allocate from.
492  * @flags: See kmalloc().
493  *
494  * Allocate an object from this cache.
495  * See kmem_cache_zalloc() for a shortcut of adding __GFP_ZERO to flags.
496  *
497  * Return: pointer to the new object or %NULL in case of error
498  */
499 void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) __assume_slab_alignment __malloc;
500 void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
501 			   gfp_t gfpflags) __assume_slab_alignment __malloc;
502 void kmem_cache_free(struct kmem_cache *s, void *objp);
503 
504 /*
505  * Bulk allocation and freeing operations. These are accelerated in an
506  * allocator specific way to avoid taking locks repeatedly or building
507  * metadata structures unnecessarily.
508  *
509  * Note that interrupts must be enabled when calling these functions.
510  */
511 void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p);
512 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p);
513 
kfree_bulk(size_t size,void ** p)514 static __always_inline void kfree_bulk(size_t size, void **p)
515 {
516 	kmem_cache_free_bulk(NULL, size, p);
517 }
518 
519 void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
520 							 __alloc_size(1);
521 void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment
522 									 __malloc;
523 
524 void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
525 		    __assume_kmalloc_alignment __alloc_size(3);
526 
527 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
528 			 int node, size_t size) __assume_kmalloc_alignment
529 						__alloc_size(4);
530 void *kmalloc_large(size_t size, gfp_t flags) __assume_page_alignment
531 					      __alloc_size(1);
532 
533 void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_alignment
534 							     __alloc_size(1);
535 
536 /**
537  * kmalloc - allocate kernel memory
538  * @size: how many bytes of memory are required.
539  * @flags: describe the allocation context
540  *
541  * kmalloc is the normal method of allocating memory
542  * for objects smaller than page size in the kernel.
543  *
544  * The allocated object address is aligned to at least ARCH_KMALLOC_MINALIGN
545  * bytes. For @size of power of two bytes, the alignment is also guaranteed
546  * to be at least to the size.
547  *
548  * The @flags argument may be one of the GFP flags defined at
549  * include/linux/gfp_types.h and described at
550  * :ref:`Documentation/core-api/mm-api.rst <mm-api-gfp-flags>`
551  *
552  * The recommended usage of the @flags is described at
553  * :ref:`Documentation/core-api/memory-allocation.rst <memory_allocation>`
554  *
555  * Below is a brief outline of the most useful GFP flags
556  *
557  * %GFP_KERNEL
558  *	Allocate normal kernel ram. May sleep.
559  *
560  * %GFP_NOWAIT
561  *	Allocation will not sleep.
562  *
563  * %GFP_ATOMIC
564  *	Allocation will not sleep.  May use emergency pools.
565  *
566  * Also it is possible to set different flags by OR'ing
567  * in one or more of the following additional @flags:
568  *
569  * %__GFP_ZERO
570  *	Zero the allocated memory before returning. Also see kzalloc().
571  *
572  * %__GFP_HIGH
573  *	This allocation has high priority and may use emergency pools.
574  *
575  * %__GFP_NOFAIL
576  *	Indicate that this allocation is in no way allowed to fail
577  *	(think twice before using).
578  *
579  * %__GFP_NORETRY
580  *	If memory is not immediately available,
581  *	then give up at once.
582  *
583  * %__GFP_NOWARN
584  *	If allocation fails, don't issue any warnings.
585  *
586  * %__GFP_RETRY_MAYFAIL
587  *	Try really hard to succeed the allocation but fail
588  *	eventually.
589  */
kmalloc(size_t size,gfp_t flags)590 static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
591 {
592 	if (__builtin_constant_p(size) && size) {
593 		unsigned int index;
594 
595 		if (size > KMALLOC_MAX_CACHE_SIZE)
596 			return kmalloc_large(size, flags);
597 
598 		index = kmalloc_index(size);
599 		return kmalloc_trace(
600 				kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
601 				flags, size);
602 	}
603 	return __kmalloc(size, flags);
604 }
605 
kmalloc_node(size_t size,gfp_t flags,int node)606 static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
607 {
608 	if (__builtin_constant_p(size) && size) {
609 		unsigned int index;
610 
611 		if (size > KMALLOC_MAX_CACHE_SIZE)
612 			return kmalloc_large_node(size, flags, node);
613 
614 		index = kmalloc_index(size);
615 		return kmalloc_node_trace(
616 				kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
617 				flags, node, size);
618 	}
619 	return __kmalloc_node(size, flags, node);
620 }
621 
622 /**
623  * kmalloc_array - allocate memory for an array.
624  * @n: number of elements.
625  * @size: element size.
626  * @flags: the type of memory to allocate (see kmalloc).
627  */
kmalloc_array(size_t n,size_t size,gfp_t flags)628 static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_t flags)
629 {
630 	size_t bytes;
631 
632 	if (unlikely(check_mul_overflow(n, size, &bytes)))
633 		return NULL;
634 	if (__builtin_constant_p(n) && __builtin_constant_p(size))
635 		return kmalloc(bytes, flags);
636 	return __kmalloc(bytes, flags);
637 }
638 
639 /**
640  * krealloc_array - reallocate memory for an array.
641  * @p: pointer to the memory chunk to reallocate
642  * @new_n: new number of elements to alloc
643  * @new_size: new size of a single member of the array
644  * @flags: the type of memory to allocate (see kmalloc)
645  */
krealloc_array(void * p,size_t new_n,size_t new_size,gfp_t flags)646 static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
647 								      size_t new_n,
648 								      size_t new_size,
649 								      gfp_t flags)
650 {
651 	size_t bytes;
652 
653 	if (unlikely(check_mul_overflow(new_n, new_size, &bytes)))
654 		return NULL;
655 
656 	return krealloc(p, bytes, flags);
657 }
658 
659 /**
660  * kcalloc - allocate memory for an array. The memory is set to zero.
661  * @n: number of elements.
662  * @size: element size.
663  * @flags: the type of memory to allocate (see kmalloc).
664  */
kcalloc(size_t n,size_t size,gfp_t flags)665 static inline __alloc_size(1, 2) void *kcalloc(size_t n, size_t size, gfp_t flags)
666 {
667 	return kmalloc_array(n, size, flags | __GFP_ZERO);
668 }
669 
670 void *__kmalloc_node_track_caller(size_t size, gfp_t flags, int node,
671 				  unsigned long caller) __alloc_size(1);
672 #define kmalloc_node_track_caller(size, flags, node) \
673 	__kmalloc_node_track_caller(size, flags, node, \
674 				    _RET_IP_)
675 
676 /*
677  * kmalloc_track_caller is a special version of kmalloc that records the
678  * calling function of the routine calling it for slab leak tracking instead
679  * of just the calling function (confusing, eh?).
680  * It's useful when the call to kmalloc comes from a widely-used standard
681  * allocator where we care about the real place the memory allocation
682  * request comes from.
683  */
684 #define kmalloc_track_caller(size, flags) \
685 	__kmalloc_node_track_caller(size, flags, \
686 				    NUMA_NO_NODE, _RET_IP_)
687 
kmalloc_array_node(size_t n,size_t size,gfp_t flags,int node)688 static inline __alloc_size(1, 2) void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
689 							  int node)
690 {
691 	size_t bytes;
692 
693 	if (unlikely(check_mul_overflow(n, size, &bytes)))
694 		return NULL;
695 	if (__builtin_constant_p(n) && __builtin_constant_p(size))
696 		return kmalloc_node(bytes, flags, node);
697 	return __kmalloc_node(bytes, flags, node);
698 }
699 
kcalloc_node(size_t n,size_t size,gfp_t flags,int node)700 static inline __alloc_size(1, 2) void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
701 {
702 	return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
703 }
704 
705 /*
706  * Shortcuts
707  */
kmem_cache_zalloc(struct kmem_cache * k,gfp_t flags)708 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
709 {
710 	return kmem_cache_alloc(k, flags | __GFP_ZERO);
711 }
712 
713 /**
714  * kzalloc - allocate memory. The memory is set to zero.
715  * @size: how many bytes of memory are required.
716  * @flags: the type of memory to allocate (see kmalloc).
717  */
kzalloc(size_t size,gfp_t flags)718 static inline __alloc_size(1) void *kzalloc(size_t size, gfp_t flags)
719 {
720 	return kmalloc(size, flags | __GFP_ZERO);
721 }
722 
723 /**
724  * kzalloc_node - allocate zeroed memory from a particular memory node.
725  * @size: how many bytes of memory are required.
726  * @flags: the type of memory to allocate (see kmalloc).
727  * @node: memory node from which to allocate
728  */
kzalloc_node(size_t size,gfp_t flags,int node)729 static inline __alloc_size(1) void *kzalloc_node(size_t size, gfp_t flags, int node)
730 {
731 	return kmalloc_node(size, flags | __GFP_ZERO, node);
732 }
733 
734 extern void *kvmalloc_node(size_t size, gfp_t flags, int node) __alloc_size(1);
kvmalloc(size_t size,gfp_t flags)735 static inline __alloc_size(1) void *kvmalloc(size_t size, gfp_t flags)
736 {
737 	return kvmalloc_node(size, flags, NUMA_NO_NODE);
738 }
kvzalloc_node(size_t size,gfp_t flags,int node)739 static inline __alloc_size(1) void *kvzalloc_node(size_t size, gfp_t flags, int node)
740 {
741 	return kvmalloc_node(size, flags | __GFP_ZERO, node);
742 }
kvzalloc(size_t size,gfp_t flags)743 static inline __alloc_size(1) void *kvzalloc(size_t size, gfp_t flags)
744 {
745 	return kvmalloc(size, flags | __GFP_ZERO);
746 }
747 
kvmalloc_array(size_t n,size_t size,gfp_t flags)748 static inline __alloc_size(1, 2) void *kvmalloc_array(size_t n, size_t size, gfp_t flags)
749 {
750 	size_t bytes;
751 
752 	if (unlikely(check_mul_overflow(n, size, &bytes)))
753 		return NULL;
754 
755 	return kvmalloc(bytes, flags);
756 }
757 
kvcalloc(size_t n,size_t size,gfp_t flags)758 static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t flags)
759 {
760 	return kvmalloc_array(n, size, flags | __GFP_ZERO);
761 }
762 
763 extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
764 		      __realloc_size(3);
765 extern void kvfree(const void *addr);
766 extern void kvfree_sensitive(const void *addr, size_t len);
767 
768 unsigned int kmem_cache_size(struct kmem_cache *s);
769 
770 /**
771  * kmalloc_size_roundup - Report allocation bucket size for the given size
772  *
773  * @size: Number of bytes to round up from.
774  *
775  * This returns the number of bytes that would be available in a kmalloc()
776  * allocation of @size bytes. For example, a 126 byte request would be
777  * rounded up to the next sized kmalloc bucket, 128 bytes. (This is strictly
778  * for the general-purpose kmalloc()-based allocations, and is not for the
779  * pre-sized kmem_cache_alloc()-based allocations.)
780  *
781  * Use this to kmalloc() the full bucket size ahead of time instead of using
782  * ksize() to query the size after an allocation.
783  */
784 size_t kmalloc_size_roundup(size_t size);
785 
786 void __init kmem_cache_init_late(void);
787 
788 #if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
789 int slab_prepare_cpu(unsigned int cpu);
790 int slab_dead_cpu(unsigned int cpu);
791 #else
792 #define slab_prepare_cpu	NULL
793 #define slab_dead_cpu		NULL
794 #endif
795 
796 #endif	/* _LINUX_SLAB_H */
797