1 /*
2  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
3  *
4  * (C) SGI 2006, Christoph Lameter
5  * 	Cleaned up and restructured to ease the addition of alternative
6  * 	implementations of SLAB allocators.
7  */
8 
9 #ifndef _LINUX_SLAB_H
10 #define	_LINUX_SLAB_H
11 
12 #include <linux/gfp.h>
13 #include <linux/types.h>
14 
15 /*
16  * Flags to pass to kmem_cache_create().
17  * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
18  */
19 #define SLAB_DEBUG_FREE		0x00000100UL	/* DEBUG: Perform (expensive) checks on free */
20 #define SLAB_RED_ZONE		0x00000400UL	/* DEBUG: Red zone objs in a cache */
21 #define SLAB_POISON		0x00000800UL	/* DEBUG: Poison objects */
22 #define SLAB_HWCACHE_ALIGN	0x00002000UL	/* Align objs on cache lines */
23 #define SLAB_CACHE_DMA		0x00004000UL	/* Use GFP_DMA memory */
24 #define SLAB_STORE_USER		0x00010000UL	/* DEBUG: Store the last owner for bug hunting */
25 #define SLAB_PANIC		0x00040000UL	/* Panic if kmem_cache_create() fails */
26 /*
27  * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
28  *
29  * This delays freeing the SLAB page by a grace period, it does _NOT_
30  * delay object freeing. This means that if you do kmem_cache_free()
31  * that memory location is free to be reused at any time. Thus it may
32  * be possible to see another object there in the same RCU grace period.
33  *
34  * This feature only ensures the memory location backing the object
35  * stays valid, the trick to using this is relying on an independent
36  * object validation pass. Something like:
37  *
38  *  rcu_read_lock()
39  * again:
40  *  obj = lockless_lookup(key);
41  *  if (obj) {
42  *    if (!try_get_ref(obj)) // might fail for free objects
43  *      goto again;
44  *
45  *    if (obj->key != key) { // not the object we expected
46  *      put_ref(obj);
47  *      goto again;
48  *    }
49  *  }
50  *  rcu_read_unlock();
51  *
52  * See also the comment on struct slab_rcu in mm/slab.c.
53  */
54 #define SLAB_DESTROY_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
55 #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */
56 #define SLAB_TRACE		0x00200000UL	/* Trace allocations and frees */
57 
58 /* Flag to prevent checks on free */
59 #ifdef CONFIG_DEBUG_OBJECTS
60 # define SLAB_DEBUG_OBJECTS	0x00400000UL
61 #else
62 # define SLAB_DEBUG_OBJECTS	0x00000000UL
63 #endif
64 
65 #define SLAB_NOLEAKTRACE	0x00800000UL	/* Avoid kmemleak tracing */
66 
67 /* Don't track use of uninitialized memory */
68 #ifdef CONFIG_KMEMCHECK
69 # define SLAB_NOTRACK		0x01000000UL
70 #else
71 # define SLAB_NOTRACK		0x00000000UL
72 #endif
73 #ifdef CONFIG_FAILSLAB
74 # define SLAB_FAILSLAB		0x02000000UL	/* Fault injection mark */
75 #else
76 # define SLAB_FAILSLAB		0x00000000UL
77 #endif
78 
79 /* The following flags affect the page allocator grouping pages by mobility */
80 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
81 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
82 /*
83  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
84  *
85  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
86  *
87  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
88  * Both make kfree a no-op.
89  */
90 #define ZERO_SIZE_PTR ((void *)16)
91 
92 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
93 				(unsigned long)ZERO_SIZE_PTR)
94 
95 /*
96  * struct kmem_cache related prototypes
97  */
98 void __init kmem_cache_init(void);
99 int slab_is_available(void);
100 
101 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
102 			unsigned long,
103 			void (*)(void *));
104 void kmem_cache_destroy(struct kmem_cache *);
105 int kmem_cache_shrink(struct kmem_cache *);
106 void kmem_cache_free(struct kmem_cache *, void *);
107 unsigned int kmem_cache_size(struct kmem_cache *);
108 
109 /*
110  * Please use this macro to create slab caches. Simply specify the
111  * name of the structure and maybe some flags that are listed above.
112  *
113  * The alignment of the struct determines object alignment. If you
114  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
115  * then the objects will be properly aligned in SMP configurations.
116  */
117 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
118 		sizeof(struct __struct), __alignof__(struct __struct),\
119 		(__flags), NULL)
120 
121 /*
122  * The largest kmalloc size supported by the slab allocators is
123  * 32 megabyte (2^25) or the maximum allocatable page order if that is
124  * less than 32 MB.
125  *
126  * WARNING: Its not easy to increase this value since the allocators have
127  * to do various tricks to work around compiler limitations in order to
128  * ensure proper constant folding.
129  */
130 #define KMALLOC_SHIFT_HIGH	((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
131 				(MAX_ORDER + PAGE_SHIFT - 1) : 25)
132 
133 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_HIGH)
134 #define KMALLOC_MAX_ORDER	(KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
135 
136 /*
137  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
138  * alignment larger than the alignment of a 64-bit integer.
139  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
140  */
141 #ifdef ARCH_DMA_MINALIGN
142 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
143 #else
144 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
145 #endif
146 
147 /*
148  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
149  * Intended for arches that get misalignment faults even for 64 bit integer
150  * aligned buffers.
151  */
152 #ifndef ARCH_SLAB_MINALIGN
153 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
154 #endif
155 
156 /*
157  * Common kmalloc functions provided by all allocators
158  */
159 void * __must_check __krealloc(const void *, size_t, gfp_t);
160 void * __must_check krealloc(const void *, size_t, gfp_t);
161 void kfree(const void *);
162 void kzfree(const void *);
163 size_t ksize(const void *);
164 
165 /*
166  * Allocator specific definitions. These are mainly used to establish optimized
167  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
168  * selecting the appropriate general cache at compile time.
169  *
170  * Allocators must define at least:
171  *
172  *	kmem_cache_alloc()
173  *	__kmalloc()
174  *	kmalloc()
175  *
176  * Those wishing to support NUMA must also define:
177  *
178  *	kmem_cache_alloc_node()
179  *	kmalloc_node()
180  *
181  * See each allocator definition file for additional comments and
182  * implementation notes.
183  */
184 #ifdef CONFIG_SLUB
185 #include <linux/slub_def.h>
186 #elif defined(CONFIG_SLOB)
187 #include <linux/slob_def.h>
188 #else
189 #include <linux/slab_def.h>
190 #endif
191 
192 /**
193  * kmalloc_array - allocate memory for an array.
194  * @n: number of elements.
195  * @size: element size.
196  * @flags: the type of memory to allocate.
197  *
198  * The @flags argument may be one of:
199  *
200  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
201  *
202  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
203  *
204  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
205  *   For example, use this inside interrupt handlers.
206  *
207  * %GFP_HIGHUSER - Allocate pages from high memory.
208  *
209  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
210  *
211  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
212  *
213  * %GFP_NOWAIT - Allocation will not sleep.
214  *
215  * %GFP_THISNODE - Allocate node-local memory only.
216  *
217  * %GFP_DMA - Allocation suitable for DMA.
218  *   Should only be used for kmalloc() caches. Otherwise, use a
219  *   slab created with SLAB_DMA.
220  *
221  * Also it is possible to set different flags by OR'ing
222  * in one or more of the following additional @flags:
223  *
224  * %__GFP_COLD - Request cache-cold pages instead of
225  *   trying to return cache-warm pages.
226  *
227  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
228  *
229  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
230  *   (think twice before using).
231  *
232  * %__GFP_NORETRY - If memory is not immediately available,
233  *   then give up at once.
234  *
235  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
236  *
237  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
238  *
239  * There are other flags available as well, but these are not intended
240  * for general use, and so are not documented here. For a full list of
241  * potential flags, always refer to linux/gfp.h.
242  */
kmalloc_array(size_t n,size_t size,gfp_t flags)243 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
244 {
245 	if (size != 0 && n > ULONG_MAX / size)
246 		return NULL;
247 	return __kmalloc(n * size, flags);
248 }
249 
250 /**
251  * kcalloc - allocate memory for an array. The memory is set to zero.
252  * @n: number of elements.
253  * @size: element size.
254  * @flags: the type of memory to allocate (see kmalloc).
255  */
kcalloc(size_t n,size_t size,gfp_t flags)256 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
257 {
258 	return kmalloc_array(n, size, flags | __GFP_ZERO);
259 }
260 
261 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
262 /**
263  * kmalloc_node - allocate memory from a specific node
264  * @size: how many bytes of memory are required.
265  * @flags: the type of memory to allocate (see kcalloc).
266  * @node: node to allocate from.
267  *
268  * kmalloc() for non-local nodes, used to allocate from a specific node
269  * if available. Equivalent to kmalloc() in the non-NUMA single-node
270  * case.
271  */
kmalloc_node(size_t size,gfp_t flags,int node)272 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
273 {
274 	return kmalloc(size, flags);
275 }
276 
__kmalloc_node(size_t size,gfp_t flags,int node)277 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
278 {
279 	return __kmalloc(size, flags);
280 }
281 
282 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
283 
kmem_cache_alloc_node(struct kmem_cache * cachep,gfp_t flags,int node)284 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
285 					gfp_t flags, int node)
286 {
287 	return kmem_cache_alloc(cachep, flags);
288 }
289 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
290 
291 /*
292  * kmalloc_track_caller is a special version of kmalloc that records the
293  * calling function of the routine calling it for slab leak tracking instead
294  * of just the calling function (confusing, eh?).
295  * It's useful when the call to kmalloc comes from a widely-used standard
296  * allocator where we care about the real place the memory allocation
297  * request comes from.
298  */
299 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
300 	(defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
301 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
302 #define kmalloc_track_caller(size, flags) \
303 	__kmalloc_track_caller(size, flags, _RET_IP_)
304 #else
305 #define kmalloc_track_caller(size, flags) \
306 	__kmalloc(size, flags)
307 #endif /* DEBUG_SLAB */
308 
309 #ifdef CONFIG_NUMA
310 /*
311  * kmalloc_node_track_caller is a special version of kmalloc_node that
312  * records the calling function of the routine calling it for slab leak
313  * tracking instead of just the calling function (confusing, eh?).
314  * It's useful when the call to kmalloc_node comes from a widely-used
315  * standard allocator where we care about the real place the memory
316  * allocation request comes from.
317  */
318 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
319 	(defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
320 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
321 #define kmalloc_node_track_caller(size, flags, node) \
322 	__kmalloc_node_track_caller(size, flags, node, \
323 			_RET_IP_)
324 #else
325 #define kmalloc_node_track_caller(size, flags, node) \
326 	__kmalloc_node(size, flags, node)
327 #endif
328 
329 #else /* CONFIG_NUMA */
330 
331 #define kmalloc_node_track_caller(size, flags, node) \
332 	kmalloc_track_caller(size, flags)
333 
334 #endif /* CONFIG_NUMA */
335 
336 /*
337  * Shortcuts
338  */
kmem_cache_zalloc(struct kmem_cache * k,gfp_t flags)339 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
340 {
341 	return kmem_cache_alloc(k, flags | __GFP_ZERO);
342 }
343 
344 /**
345  * kzalloc - allocate memory. The memory is set to zero.
346  * @size: how many bytes of memory are required.
347  * @flags: the type of memory to allocate (see kmalloc).
348  */
kzalloc(size_t size,gfp_t flags)349 static inline void *kzalloc(size_t size, gfp_t flags)
350 {
351 	return kmalloc(size, flags | __GFP_ZERO);
352 }
353 
354 /**
355  * kzalloc_node - allocate zeroed memory from a particular memory node.
356  * @size: how many bytes of memory are required.
357  * @flags: the type of memory to allocate (see kmalloc).
358  * @node: memory node from which to allocate
359  */
kzalloc_node(size_t size,gfp_t flags,int node)360 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
361 {
362 	return kmalloc_node(size, flags | __GFP_ZERO, node);
363 }
364 
365 void __init kmem_cache_init_late(void);
366 
367 #endif	/* _LINUX_SLAB_H */
368