2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1987, 1993
5 * The Regents of the University of California.
6 * Copyright (c) 2005, 2009 Robert N. M. Watson
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33 * @(#)malloc.h 8.5 (Berkeley) 5/3/95
37 #ifndef _SYS_MALLOC_H_
38 #define _SYS_MALLOC_H_
40 #include <sys/param.h>
42 #include <sys/systm.h>
44 #include <sys/queue.h>
45 #include <sys/_lock.h>
46 #include <sys/_mutex.h>
47 #include <machine/_limits.h>
49 #define MINALLOCSIZE UMA_SMALLEST_UNIT
52 * Flags to memory allocation functions.
54 #define M_NOWAIT 0x0001 /* do not block */
55 #define M_WAITOK 0x0002 /* ok to block */
56 #define M_ZERO 0x0100 /* bzero the allocation */
57 #define M_NOVM 0x0200 /* don't ask VM for pages */
58 #define M_USE_RESERVE 0x0400 /* can alloc out of reserve memory */
59 #define M_NODUMP 0x0800 /* don't dump pages in this allocation */
60 #define M_FIRSTFIT 0x1000 /* Only for vmem, fast fit. */
61 #define M_BESTFIT 0x2000 /* Only for vmem, low fragmentation. */
62 #define M_EXEC 0x4000 /* allocate executable space. */
64 #define M_MAGIC 877983977 /* time when first defined :-) */
67 * Two malloc type structures are present: malloc_type, which is used by a
68 * type owner to declare the type, and malloc_type_internal, which holds
69 * malloc-owned statistics and other ABI-sensitive fields, such as the set of
70 * malloc statistics indexed by the compile-time MAXCPU constant.
71 * Applications should avoid introducing dependence on the allocator private
72 * data layout and size.
74 * The malloc_type ks_next field is protected by malloc_mtx. Other fields in
75 * malloc_type are static after initialization so unsynchronized.
77 * Statistics in malloc_type_stats are written only when holding a critical
78 * section and running on the CPU associated with the index into the stat
79 * array, but read lock-free resulting in possible (minor) races, which the
80 * monitoring app should take into account.
82 struct malloc_type_stats {
83 uint64_t mts_memalloced; /* Bytes allocated on CPU. */
84 uint64_t mts_memfreed; /* Bytes freed on CPU. */
85 uint64_t mts_numallocs; /* Number of allocates on CPU. */
86 uint64_t mts_numfrees; /* number of frees on CPU. */
87 uint64_t mts_size; /* Bitmask of sizes allocated on CPU. */
88 uint64_t _mts_reserved1; /* Reserved field. */
89 uint64_t _mts_reserved2; /* Reserved field. */
90 uint64_t _mts_reserved3; /* Reserved field. */
94 * Index definitions for the mti_probes[] array.
96 #define DTMALLOC_PROBE_MALLOC 0
97 #define DTMALLOC_PROBE_FREE 1
98 #define DTMALLOC_PROBE_MAX 2
100 struct malloc_type_internal {
101 uint32_t mti_probes[DTMALLOC_PROBE_MAX];
102 /* DTrace probe ID array. */
104 struct malloc_type_stats *mti_stats;
108 * Public data structure describing a malloc type. Private data is hung off
109 * of ks_handle to avoid encoding internal malloc(9) data structures in
110 * modules, which will statically allocate struct malloc_type.
113 struct malloc_type *ks_next; /* Next in global chain. */
114 u_long ks_magic; /* Detect programmer error. */
115 const char *ks_shortdesc; /* Printable type name. */
116 void *ks_handle; /* Priv. data, was lo_class. */
120 * Statistics structure headers for user space. The kern.malloc sysctl
121 * exposes a structure stream consisting of a stream header, then a series of
122 * malloc type headers and statistics structures (quantity maxcpus). For
123 * convenience, the kernel will provide the current value of maxcpus at the
124 * head of the stream.
126 #define MALLOC_TYPE_STREAM_VERSION 0x00000001
127 struct malloc_type_stream_header {
128 uint32_t mtsh_version; /* Stream format version. */
129 uint32_t mtsh_maxcpus; /* Value of MAXCPU for stream. */
130 uint32_t mtsh_count; /* Number of records. */
131 uint32_t _mtsh_pad; /* Pad/reserved field. */
134 #define MALLOC_MAX_NAME 32
135 struct malloc_type_header {
136 char mth_name[MALLOC_MAX_NAME];
140 #define MALLOC_DEFINE(type, shortdesc, longdesc) \
141 struct malloc_type type[1] = { \
142 { NULL, M_MAGIC, shortdesc, NULL } \
144 SYSINIT(type##_init, SI_SUB_KMEM, SI_ORDER_THIRD, malloc_init, \
146 SYSUNINIT(type##_uninit, SI_SUB_KMEM, SI_ORDER_ANY, \
149 #define MALLOC_DECLARE(type) \
150 extern struct malloc_type type[1]
152 MALLOC_DECLARE(M_CACHE);
153 MALLOC_DECLARE(M_DEVBUF);
154 MALLOC_DECLARE(M_TEMP);
157 * XXX this should be declared in <sys/uio.h>, but that tends to fail
158 * because <sys/uio.h> is included in a header before the source file
159 * has a chance to include <sys/malloc.h> to get MALLOC_DECLARE() defined.
161 MALLOC_DECLARE(M_IOV);
164 extern struct mtx malloc_mtx;
167 * Function type used when iterating over the list of malloc types.
169 typedef void malloc_type_list_func_t(struct malloc_type *, void *);
171 void contigfree(void *addr, unsigned long size, struct malloc_type *type);
172 void *contigmalloc(unsigned long size, struct malloc_type *type, int flags,
173 vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
174 vm_paddr_t boundary) __malloc_like __result_use_check
175 __alloc_size(1) __alloc_align(6);
176 void *contigmalloc_domainset(unsigned long size, struct malloc_type *type,
177 struct domainset *ds, int flags, vm_paddr_t low, vm_paddr_t high,
178 unsigned long alignment, vm_paddr_t boundary)
179 __malloc_like __result_use_check __alloc_size(1) __alloc_align(6);
180 void free(void *addr, struct malloc_type *type);
181 void free_domain(void *addr, struct malloc_type *type);
182 void *malloc(size_t size, struct malloc_type *type, int flags) __malloc_like
183 __result_use_check __alloc_size(1);
185 * Try to optimize malloc(..., ..., M_ZERO) allocations by doing zeroing in
186 * place if the size is known at compilation time.
188 * Passing the flag down requires malloc to blindly zero the entire object.
189 * In practice a lot of the zeroing can be avoided if most of the object
190 * gets explicitly initialized after the allocation. Letting the compiler
191 * zero in place gives it the opportunity to take advantage of this state.
193 * Note that the operation is only applicable if both flags and size are
194 * known at compilation time. If M_ZERO is passed but M_WAITOK is not, the
195 * allocation can fail and a NULL check is needed. However, if M_WAITOK is
196 * passed we know the allocation must succeed and the check can be elided.
198 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
199 * if (((flags) & M_WAITOK) != 0 || _malloc_item != NULL)
200 * bzero(_malloc_item, _size);
202 * If the flag is set, the compiler knows the left side is always true,
203 * therefore the entire statement is true and the callsite is:
205 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
206 * bzero(_malloc_item, _size);
208 * If the flag is not set, the compiler knows the left size is always false
209 * and the NULL check is needed, therefore the callsite is:
211 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
212 * if (_malloc_item != NULL)
213 * bzero(_malloc_item, _size);
215 * The implementation is a macro because of what appears to be a clang 6 bug:
216 * an inline function variant ended up being compiled to a mere malloc call
217 * regardless of argument. gcc generates expected code (like the above).
219 #define malloc(size, type, flags) ({ \
220 void *_malloc_item; \
221 size_t _size = (size); \
222 if (__builtin_constant_p(size) && __builtin_constant_p(flags) &&\
223 ((flags) & M_ZERO) != 0) { \
224 _malloc_item = malloc(_size, type, (flags) &~ M_ZERO); \
225 if (((flags) & M_WAITOK) != 0 || \
226 __predict_true(_malloc_item != NULL)) \
227 bzero(_malloc_item, _size); \
229 _malloc_item = malloc(_size, type, flags); \
234 void *malloc_domainset(size_t size, struct malloc_type *type,
235 struct domainset *ds, int flags) __malloc_like __result_use_check
237 void *mallocarray(size_t nmemb, size_t size, struct malloc_type *type,
238 int flags) __malloc_like __result_use_check
240 void malloc_init(void *);
241 int malloc_last_fail(void);
242 void malloc_type_allocated(struct malloc_type *type, unsigned long size);
243 void malloc_type_freed(struct malloc_type *type, unsigned long size);
244 void malloc_type_list(malloc_type_list_func_t *, void *);
245 void malloc_uninit(void *);
246 void *realloc(void *addr, size_t size, struct malloc_type *type, int flags)
247 __result_use_check __alloc_size(2);
248 void *reallocf(void *addr, size_t size, struct malloc_type *type, int flags)
249 __result_use_check __alloc_size(2);
251 struct malloc_type *malloc_desc2type(const char *desc);
254 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
255 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
257 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 8 / 2))
259 WOULD_OVERFLOW(size_t nmemb, size_t size)
262 return ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
263 nmemb > 0 && __SIZE_T_MAX / nmemb < size);
265 #undef MUL_NO_OVERFLOW
268 #endif /* !_SYS_MALLOC_H_ */