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  1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef MM_SLAB_H
  3#define MM_SLAB_H
  4
  5#include <linux/reciprocal_div.h>
  6#include <linux/list_lru.h>
  7#include <linux/local_lock.h>
  8#include <linux/random.h>
  9#include <linux/kobject.h>
 10#include <linux/sched/mm.h>
 11#include <linux/memcontrol.h>
 12#include <linux/kfence.h>
 13#include <linux/kasan.h>
 14
 15/*
 16 * Internal slab definitions
 17 */
 18
 19#ifdef CONFIG_64BIT
 20# ifdef system_has_cmpxchg128
 21# define system_has_freelist_aba()	system_has_cmpxchg128()
 22# define try_cmpxchg_freelist		try_cmpxchg128
 23# endif
 24#define this_cpu_try_cmpxchg_freelist	this_cpu_try_cmpxchg128
 25typedef u128 freelist_full_t;
 26#else /* CONFIG_64BIT */
 27# ifdef system_has_cmpxchg64
 28# define system_has_freelist_aba()	system_has_cmpxchg64()
 29# define try_cmpxchg_freelist		try_cmpxchg64
 30# endif
 31#define this_cpu_try_cmpxchg_freelist	this_cpu_try_cmpxchg64
 32typedef u64 freelist_full_t;
 33#endif /* CONFIG_64BIT */
 34
 35#if defined(system_has_freelist_aba) && !defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
 36#undef system_has_freelist_aba
 37#endif
 38
 39/*
 40 * Freelist pointer and counter to cmpxchg together, avoids the typical ABA
 41 * problems with cmpxchg of just a pointer.
 42 */
 43typedef union {
 44	struct {
 45		void *freelist;
 46		unsigned long counter;
 47	};
 48	freelist_full_t full;
 49} freelist_aba_t;
 50
 51/* Reuses the bits in struct page */
 52struct slab {
 53	unsigned long __page_flags;
 54
 55	struct kmem_cache *slab_cache;
 56	union {
 57		struct {
 58			union {
 59				struct list_head slab_list;
 60#ifdef CONFIG_SLUB_CPU_PARTIAL
 61				struct {
 62					struct slab *next;
 63					int slabs;	/* Nr of slabs left */
 64				};
 65#endif
 66			};
 67			/* Double-word boundary */
 68			union {
 69				struct {
 70					void *freelist;		/* first free object */
 71					union {
 72						unsigned long counters;
 73						struct {
 74							unsigned inuse:16;
 75							unsigned objects:15;
 76							unsigned frozen:1;
 77						};
 78					};
 79				};
 80#ifdef system_has_freelist_aba
 81				freelist_aba_t freelist_counter;
 82#endif
 83			};
 84		};
 85		struct rcu_head rcu_head;
 86	};
 87	unsigned int __unused;
 88
 89	atomic_t __page_refcount;
 90#ifdef CONFIG_MEMCG
 91	unsigned long memcg_data;
 92#endif
 93};
 94
 95#define SLAB_MATCH(pg, sl)						\
 96	static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl))
 97SLAB_MATCH(flags, __page_flags);
 98SLAB_MATCH(compound_head, slab_cache);	/* Ensure bit 0 is clear */
 99SLAB_MATCH(_refcount, __page_refcount);
100#ifdef CONFIG_MEMCG
101SLAB_MATCH(memcg_data, memcg_data);
102#endif
103#undef SLAB_MATCH
104static_assert(sizeof(struct slab) <= sizeof(struct page));
105#if defined(system_has_freelist_aba)
106static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(freelist_aba_t)));
107#endif
108
109/**
110 * folio_slab - Converts from folio to slab.
111 * @folio: The folio.
112 *
113 * Currently struct slab is a different representation of a folio where
114 * folio_test_slab() is true.
115 *
116 * Return: The slab which contains this folio.
117 */
118#define folio_slab(folio)	(_Generic((folio),			\
119	const struct folio *:	(const struct slab *)(folio),		\
120	struct folio *:		(struct slab *)(folio)))
121
122/**
123 * slab_folio - The folio allocated for a slab
124 * @slab: The slab.
125 *
126 * Slabs are allocated as folios that contain the individual objects and are
127 * using some fields in the first struct page of the folio - those fields are
128 * now accessed by struct slab. It is occasionally necessary to convert back to
129 * a folio in order to communicate with the rest of the mm.  Please use this
130 * helper function instead of casting yourself, as the implementation may change
131 * in the future.
132 */
133#define slab_folio(s)		(_Generic((s),				\
134	const struct slab *:	(const struct folio *)s,		\
135	struct slab *:		(struct folio *)s))
136
137/**
138 * page_slab - Converts from first struct page to slab.
139 * @p: The first (either head of compound or single) page of slab.
140 *
141 * A temporary wrapper to convert struct page to struct slab in situations where
142 * we know the page is the compound head, or single order-0 page.
143 *
144 * Long-term ideally everything would work with struct slab directly or go
145 * through folio to struct slab.
146 *
147 * Return: The slab which contains this page
148 */
149#define page_slab(p)		(_Generic((p),				\
150	const struct page *:	(const struct slab *)(p),		\
151	struct page *:		(struct slab *)(p)))
152
153/**
154 * slab_page - The first struct page allocated for a slab
155 * @slab: The slab.
156 *
157 * A convenience wrapper for converting slab to the first struct page of the
158 * underlying folio, to communicate with code not yet converted to folio or
159 * struct slab.
160 */
161#define slab_page(s) folio_page(slab_folio(s), 0)
162
163/*
164 * If network-based swap is enabled, sl*b must keep track of whether pages
165 * were allocated from pfmemalloc reserves.
166 */
167static inline bool slab_test_pfmemalloc(const struct slab *slab)
168{
169	return folio_test_active((struct folio *)slab_folio(slab));
170}
171
172static inline void slab_set_pfmemalloc(struct slab *slab)
173{
174	folio_set_active(slab_folio(slab));
175}
176
177static inline void slab_clear_pfmemalloc(struct slab *slab)
178{
179	folio_clear_active(slab_folio(slab));
180}
181
182static inline void __slab_clear_pfmemalloc(struct slab *slab)
183{
184	__folio_clear_active(slab_folio(slab));
185}
186
187static inline void *slab_address(const struct slab *slab)
188{
189	return folio_address(slab_folio(slab));
190}
191
192static inline int slab_nid(const struct slab *slab)
193{
194	return folio_nid(slab_folio(slab));
195}
196
197static inline pg_data_t *slab_pgdat(const struct slab *slab)
198{
199	return folio_pgdat(slab_folio(slab));
200}
201
202static inline struct slab *virt_to_slab(const void *addr)
203{
204	struct folio *folio = virt_to_folio(addr);
205
206	if (!folio_test_slab(folio))
207		return NULL;
208
209	return folio_slab(folio);
210}
211
212static inline int slab_order(const struct slab *slab)
213{
214	return folio_order((struct folio *)slab_folio(slab));
215}
216
217static inline size_t slab_size(const struct slab *slab)
218{
219	return PAGE_SIZE << slab_order(slab);
220}
221
222#ifdef CONFIG_SLUB_CPU_PARTIAL
223#define slub_percpu_partial(c)			((c)->partial)
224
225#define slub_set_percpu_partial(c, p)		\
226({						\
227	slub_percpu_partial(c) = (p)->next;	\
228})
229
230#define slub_percpu_partial_read_once(c)	READ_ONCE(slub_percpu_partial(c))
231#else
232#define slub_percpu_partial(c)			NULL
233
234#define slub_set_percpu_partial(c, p)
235
236#define slub_percpu_partial_read_once(c)	NULL
237#endif // CONFIG_SLUB_CPU_PARTIAL
238
239/*
240 * Word size structure that can be atomically updated or read and that
241 * contains both the order and the number of objects that a slab of the
242 * given order would contain.
243 */
244struct kmem_cache_order_objects {
245	unsigned int x;
246};
247
248/*
249 * Slab cache management.
250 */
251struct kmem_cache {
252#ifndef CONFIG_SLUB_TINY
253	struct kmem_cache_cpu __percpu *cpu_slab;
254#endif
255	/* Used for retrieving partial slabs, etc. */
256	slab_flags_t flags;
257	unsigned long min_partial;
258	unsigned int size;		/* Object size including metadata */
259	unsigned int object_size;	/* Object size without metadata */
260	struct reciprocal_value reciprocal_size;
261	unsigned int offset;		/* Free pointer offset */
262#ifdef CONFIG_SLUB_CPU_PARTIAL
263	/* Number of per cpu partial objects to keep around */
264	unsigned int cpu_partial;
265	/* Number of per cpu partial slabs to keep around */
266	unsigned int cpu_partial_slabs;
267#endif
268	struct kmem_cache_order_objects oo;
269
270	/* Allocation and freeing of slabs */
271	struct kmem_cache_order_objects min;
272	gfp_t allocflags;		/* gfp flags to use on each alloc */
273	int refcount;			/* Refcount for slab cache destroy */
274	void (*ctor)(void *object);	/* Object constructor */
275	unsigned int inuse;		/* Offset to metadata */
276	unsigned int align;		/* Alignment */
277	unsigned int red_left_pad;	/* Left redzone padding size */
278	const char *name;		/* Name (only for display!) */
279	struct list_head list;		/* List of slab caches */
280#ifdef CONFIG_SYSFS
281	struct kobject kobj;		/* For sysfs */
282#endif
283#ifdef CONFIG_SLAB_FREELIST_HARDENED
284	unsigned long random;
285#endif
286
287#ifdef CONFIG_NUMA
288	/*
289	 * Defragmentation by allocating from a remote node.
290	 */
291	unsigned int remote_node_defrag_ratio;
292#endif
293
294#ifdef CONFIG_SLAB_FREELIST_RANDOM
295	unsigned int *random_seq;
296#endif
297
298#ifdef CONFIG_KASAN_GENERIC
299	struct kasan_cache kasan_info;
300#endif
301
302#ifdef CONFIG_HARDENED_USERCOPY
303	unsigned int useroffset;	/* Usercopy region offset */
304	unsigned int usersize;		/* Usercopy region size */
305#endif
306
307	struct kmem_cache_node *node[MAX_NUMNODES];
308};
309
310#if defined(CONFIG_SYSFS) && !defined(CONFIG_SLUB_TINY)
311#define SLAB_SUPPORTS_SYSFS
312void sysfs_slab_unlink(struct kmem_cache *s);
313void sysfs_slab_release(struct kmem_cache *s);
314#else
315static inline void sysfs_slab_unlink(struct kmem_cache *s) { }
316static inline void sysfs_slab_release(struct kmem_cache *s) { }
317#endif
318
319void *fixup_red_left(struct kmem_cache *s, void *p);
320
321static inline void *nearest_obj(struct kmem_cache *cache,
322				const struct slab *slab, void *x)
323{
324	void *object = x - (x - slab_address(slab)) % cache->size;
325	void *last_object = slab_address(slab) +
326		(slab->objects - 1) * cache->size;
327	void *result = (unlikely(object > last_object)) ? last_object : object;
328
329	result = fixup_red_left(cache, result);
330	return result;
331}
332
333/* Determine object index from a given position */
334static inline unsigned int __obj_to_index(const struct kmem_cache *cache,
335					  void *addr, void *obj)
336{
337	return reciprocal_divide(kasan_reset_tag(obj) - addr,
338				 cache->reciprocal_size);
339}
340
341static inline unsigned int obj_to_index(const struct kmem_cache *cache,
342					const struct slab *slab, void *obj)
343{
344	if (is_kfence_address(obj))
345		return 0;
346	return __obj_to_index(cache, slab_address(slab), obj);
347}
348
349static inline int objs_per_slab(const struct kmem_cache *cache,
350				const struct slab *slab)
351{
352	return slab->objects;
353}
354
355/*
356 * State of the slab allocator.
357 *
358 * This is used to describe the states of the allocator during bootup.
359 * Allocators use this to gradually bootstrap themselves. Most allocators
360 * have the problem that the structures used for managing slab caches are
361 * allocated from slab caches themselves.
362 */
363enum slab_state {
364	DOWN,			/* No slab functionality yet */
365	PARTIAL,		/* SLUB: kmem_cache_node available */
366	PARTIAL_NODE,		/* SLAB: kmalloc size for node struct available */
367	UP,			/* Slab caches usable but not all extras yet */
368	FULL			/* Everything is working */
369};
370
371extern enum slab_state slab_state;
372
373/* The slab cache mutex protects the management structures during changes */
374extern struct mutex slab_mutex;
375
376/* The list of all slab caches on the system */
377extern struct list_head slab_caches;
378
379/* The slab cache that manages slab cache information */
380extern struct kmem_cache *kmem_cache;
381
382/* A table of kmalloc cache names and sizes */
383extern const struct kmalloc_info_struct {
384	const char *name[NR_KMALLOC_TYPES];
385	unsigned int size;
386} kmalloc_info[];
387
388/* Kmalloc array related functions */
389void setup_kmalloc_cache_index_table(void);
390void create_kmalloc_caches(slab_flags_t);
391
392extern u8 kmalloc_size_index[24];
393
394static inline unsigned int size_index_elem(unsigned int bytes)
395{
396	return (bytes - 1) / 8;
397}
398
399/*
400 * Find the kmem_cache structure that serves a given size of
401 * allocation
402 *
403 * This assumes size is larger than zero and not larger than
404 * KMALLOC_MAX_CACHE_SIZE and the caller must check that.
405 */
406static inline struct kmem_cache *
407kmalloc_slab(size_t size, gfp_t flags, unsigned long caller)
408{
409	unsigned int index;
410
411	if (size <= 192)
412		index = kmalloc_size_index[size_index_elem(size)];
413	else
414		index = fls(size - 1);
415
416	return kmalloc_caches[kmalloc_type(flags, caller)][index];
417}
418
419gfp_t kmalloc_fix_flags(gfp_t flags);
420
421/* Functions provided by the slab allocators */
422int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
423
424void __init kmem_cache_init(void);
425void __init new_kmalloc_cache(int idx, enum kmalloc_cache_type type,
426			      slab_flags_t flags);
427extern void create_boot_cache(struct kmem_cache *, const char *name,
428			unsigned int size, slab_flags_t flags,
429			unsigned int useroffset, unsigned int usersize);
430
431int slab_unmergeable(struct kmem_cache *s);
432struct kmem_cache *find_mergeable(unsigned size, unsigned align,
433		slab_flags_t flags, const char *name, void (*ctor)(void *));
434struct kmem_cache *
435__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
436		   slab_flags_t flags, void (*ctor)(void *));
437
438slab_flags_t kmem_cache_flags(unsigned int object_size,
439	slab_flags_t flags, const char *name);
440
441static inline bool is_kmalloc_cache(struct kmem_cache *s)
442{
443	return (s->flags & SLAB_KMALLOC);
444}
445
446/* Legal flag mask for kmem_cache_create(), for various configurations */
447#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \
448			 SLAB_CACHE_DMA32 | SLAB_PANIC | \
449			 SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
450
451#ifdef CONFIG_SLUB_DEBUG
452#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
453			  SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
454#else
455#define SLAB_DEBUG_FLAGS (0)
456#endif
457
458#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
459			  SLAB_TEMPORARY | SLAB_ACCOUNT | \
460			  SLAB_NO_USER_FLAGS | SLAB_KMALLOC | SLAB_NO_MERGE)
461
462/* Common flags available with current configuration */
463#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
464
465/* Common flags permitted for kmem_cache_create */
466#define SLAB_FLAGS_PERMITTED (SLAB_CORE_FLAGS | \
467			      SLAB_RED_ZONE | \
468			      SLAB_POISON | \
469			      SLAB_STORE_USER | \
470			      SLAB_TRACE | \
471			      SLAB_CONSISTENCY_CHECKS | \
472			      SLAB_MEM_SPREAD | \
473			      SLAB_NOLEAKTRACE | \
474			      SLAB_RECLAIM_ACCOUNT | \
475			      SLAB_TEMPORARY | \
476			      SLAB_ACCOUNT | \
477			      SLAB_KMALLOC | \
478			      SLAB_NO_MERGE | \
479			      SLAB_NO_USER_FLAGS)
480
481bool __kmem_cache_empty(struct kmem_cache *);
482int __kmem_cache_shutdown(struct kmem_cache *);
483void __kmem_cache_release(struct kmem_cache *);
484int __kmem_cache_shrink(struct kmem_cache *);
485void slab_kmem_cache_release(struct kmem_cache *);
486
487struct seq_file;
488struct file;
489
490struct slabinfo {
491	unsigned long active_objs;
492	unsigned long num_objs;
493	unsigned long active_slabs;
494	unsigned long num_slabs;
495	unsigned long shared_avail;
496	unsigned int limit;
497	unsigned int batchcount;
498	unsigned int shared;
499	unsigned int objects_per_slab;
500	unsigned int cache_order;
501};
502
503void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
504void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
505ssize_t slabinfo_write(struct file *file, const char __user *buffer,
506		       size_t count, loff_t *ppos);
507
508#ifdef CONFIG_SLUB_DEBUG
509#ifdef CONFIG_SLUB_DEBUG_ON
510DECLARE_STATIC_KEY_TRUE(slub_debug_enabled);
511#else
512DECLARE_STATIC_KEY_FALSE(slub_debug_enabled);
513#endif
514extern void print_tracking(struct kmem_cache *s, void *object);
515long validate_slab_cache(struct kmem_cache *s);
516static inline bool __slub_debug_enabled(void)
517{
518	return static_branch_unlikely(&slub_debug_enabled);
519}
520#else
521static inline void print_tracking(struct kmem_cache *s, void *object)
522{
523}
524static inline bool __slub_debug_enabled(void)
525{
526	return false;
527}
528#endif
529
530/*
531 * Returns true if any of the specified slub_debug flags is enabled for the
532 * cache. Use only for flags parsed by setup_slub_debug() as it also enables
533 * the static key.
534 */
535static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t flags)
536{
537	if (IS_ENABLED(CONFIG_SLUB_DEBUG))
538		VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS));
539	if (__slub_debug_enabled())
540		return s->flags & flags;
541	return false;
542}
543
544#ifdef CONFIG_MEMCG_KMEM
545/*
546 * slab_objcgs - get the object cgroups vector associated with a slab
547 * @slab: a pointer to the slab struct
548 *
549 * Returns a pointer to the object cgroups vector associated with the slab,
550 * or NULL if no such vector has been associated yet.
551 */
552static inline struct obj_cgroup **slab_objcgs(struct slab *slab)
553{
554	unsigned long memcg_data = READ_ONCE(slab->memcg_data);
555
556	VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS),
557							slab_page(slab));
558	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, slab_page(slab));
559
560	return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
561}
562
563int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
564				 gfp_t gfp, bool new_slab);
565void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
566		     enum node_stat_item idx, int nr);
567#else /* CONFIG_MEMCG_KMEM */
568static inline struct obj_cgroup **slab_objcgs(struct slab *slab)
569{
570	return NULL;
571}
572
573static inline int memcg_alloc_slab_cgroups(struct slab *slab,
574					       struct kmem_cache *s, gfp_t gfp,
575					       bool new_slab)
576{
577	return 0;
578}
579#endif /* CONFIG_MEMCG_KMEM */
580
581size_t __ksize(const void *objp);
582
583static inline size_t slab_ksize(const struct kmem_cache *s)
584{
585#ifdef CONFIG_SLUB_DEBUG
586	/*
587	 * Debugging requires use of the padding between object
588	 * and whatever may come after it.
589	 */
590	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
591		return s->object_size;
592#endif
593	if (s->flags & SLAB_KASAN)
594		return s->object_size;
595	/*
596	 * If we have the need to store the freelist pointer
597	 * back there or track user information then we can
598	 * only use the space before that information.
599	 */
600	if (s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_STORE_USER))
601		return s->inuse;
602	/*
603	 * Else we can use all the padding etc for the allocation
604	 */
605	return s->size;
606}
607
608#ifdef CONFIG_SLUB_DEBUG
609void dump_unreclaimable_slab(void);
610#else
611static inline void dump_unreclaimable_slab(void)
612{
613}
614#endif
615
616void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr);
617
618#ifdef CONFIG_SLAB_FREELIST_RANDOM
619int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
620			gfp_t gfp);
621void cache_random_seq_destroy(struct kmem_cache *cachep);
622#else
623static inline int cache_random_seq_create(struct kmem_cache *cachep,
624					unsigned int count, gfp_t gfp)
625{
626	return 0;
627}
628static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
629#endif /* CONFIG_SLAB_FREELIST_RANDOM */
630
631static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
632{
633	if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON,
634				&init_on_alloc)) {
635		if (c->ctor)
636			return false;
637		if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
638			return flags & __GFP_ZERO;
639		return true;
640	}
641	return flags & __GFP_ZERO;
642}
643
644static inline bool slab_want_init_on_free(struct kmem_cache *c)
645{
646	if (static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON,
647				&init_on_free))
648		return !(c->ctor ||
649			 (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)));
650	return false;
651}
652
653#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
654void debugfs_slab_release(struct kmem_cache *);
655#else
656static inline void debugfs_slab_release(struct kmem_cache *s) { }
657#endif
658
659#ifdef CONFIG_PRINTK
660#define KS_ADDRS_COUNT 16
661struct kmem_obj_info {
662	void *kp_ptr;
663	struct slab *kp_slab;
664	void *kp_objp;
665	unsigned long kp_data_offset;
666	struct kmem_cache *kp_slab_cache;
667	void *kp_ret;
668	void *kp_stack[KS_ADDRS_COUNT];
669	void *kp_free_stack[KS_ADDRS_COUNT];
670};
671void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab);
672#endif
673
674void __check_heap_object(const void *ptr, unsigned long n,
675			 const struct slab *slab, bool to_user);
676
677#ifdef CONFIG_SLUB_DEBUG
678void skip_orig_size_check(struct kmem_cache *s, const void *object);
679#endif
680
681#endif /* MM_SLAB_H */