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 */
63 #define M_NEXTFIT 0x8000 /* only for vmem, follow cursor */
65 #define M_MAGIC 877983977 /* time when first defined :-) */
68 * Two malloc type structures are present: malloc_type, which is used by a
69 * type owner to declare the type, and malloc_type_internal, which holds
70 * malloc-owned statistics and other ABI-sensitive fields, such as the set of
71 * malloc statistics indexed by the compile-time MAXCPU constant.
72 * Applications should avoid introducing dependence on the allocator private
73 * data layout and size.
75 * The malloc_type ks_next field is protected by malloc_mtx. Other fields in
76 * malloc_type are static after initialization so unsynchronized.
78 * Statistics in malloc_type_stats are written only when holding a critical
79 * section and running on the CPU associated with the index into the stat
80 * array, but read lock-free resulting in possible (minor) races, which the
81 * monitoring app should take into account.
83 struct malloc_type_stats {
84 uint64_t mts_memalloced; /* Bytes allocated on CPU. */
85 uint64_t mts_memfreed; /* Bytes freed on CPU. */
86 uint64_t mts_numallocs; /* Number of allocates on CPU. */
87 uint64_t mts_numfrees; /* number of frees on CPU. */
88 uint64_t mts_size; /* Bitmask of sizes allocated on CPU. */
89 uint64_t _mts_reserved1; /* Reserved field. */
90 uint64_t _mts_reserved2; /* Reserved field. */
91 uint64_t _mts_reserved3; /* Reserved field. */
95 * Index definitions for the mti_probes[] array.
97 #define DTMALLOC_PROBE_MALLOC 0
98 #define DTMALLOC_PROBE_FREE 1
99 #define DTMALLOC_PROBE_MAX 2
101 struct malloc_type_internal {
102 uint32_t mti_probes[DTMALLOC_PROBE_MAX];
103 /* DTrace probe ID array. */
105 struct malloc_type_stats *mti_stats;
109 * Public data structure describing a malloc type. Private data is hung off
110 * of ks_handle to avoid encoding internal malloc(9) data structures in
111 * modules, which will statically allocate struct malloc_type.
114 struct malloc_type *ks_next; /* Next in global chain. */
115 u_long ks_magic; /* Detect programmer error. */
116 const char *ks_shortdesc; /* Printable type name. */
117 void *ks_handle; /* Priv. data, was lo_class. */
121 * Statistics structure headers for user space. The kern.malloc sysctl
122 * exposes a structure stream consisting of a stream header, then a series of
123 * malloc type headers and statistics structures (quantity maxcpus). For
124 * convenience, the kernel will provide the current value of maxcpus at the
125 * head of the stream.
127 #define MALLOC_TYPE_STREAM_VERSION 0x00000001
128 struct malloc_type_stream_header {
129 uint32_t mtsh_version; /* Stream format version. */
130 uint32_t mtsh_maxcpus; /* Value of MAXCPU for stream. */
131 uint32_t mtsh_count; /* Number of records. */
132 uint32_t _mtsh_pad; /* Pad/reserved field. */
135 #define MALLOC_MAX_NAME 32
136 struct malloc_type_header {
137 char mth_name[MALLOC_MAX_NAME];
141 #define MALLOC_DEFINE(type, shortdesc, longdesc) \
142 struct malloc_type type[1] = { \
143 { NULL, M_MAGIC, shortdesc, NULL } \
145 SYSINIT(type##_init, SI_SUB_KMEM, SI_ORDER_THIRD, malloc_init, \
147 SYSUNINIT(type##_uninit, SI_SUB_KMEM, SI_ORDER_ANY, \
150 #define MALLOC_DECLARE(type) \
151 extern struct malloc_type type[1]
153 MALLOC_DECLARE(M_CACHE);
154 MALLOC_DECLARE(M_DEVBUF);
155 MALLOC_DECLARE(M_TEMP);
158 * XXX this should be declared in <sys/uio.h>, but that tends to fail
159 * because <sys/uio.h> is included in a header before the source file
160 * has a chance to include <sys/malloc.h> to get MALLOC_DECLARE() defined.
162 MALLOC_DECLARE(M_IOV);
165 extern struct mtx malloc_mtx;
168 * Function type used when iterating over the list of malloc types.
170 typedef void malloc_type_list_func_t(struct malloc_type *, void *);
172 void contigfree(void *addr, unsigned long size, struct malloc_type *type);
173 void *contigmalloc(unsigned long size, struct malloc_type *type, int flags,
174 vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
175 vm_paddr_t boundary) __malloc_like __result_use_check
176 __alloc_size(1) __alloc_align(6);
177 void *contigmalloc_domainset(unsigned long size, struct malloc_type *type,
178 struct domainset *ds, int flags, vm_paddr_t low, vm_paddr_t high,
179 unsigned long alignment, vm_paddr_t boundary)
180 __malloc_like __result_use_check __alloc_size(1) __alloc_align(7);
181 void free(void *addr, struct malloc_type *type);
182 void free_domain(void *addr, struct malloc_type *type);
183 void *malloc(size_t size, struct malloc_type *type, int flags) __malloc_like
184 __result_use_check __alloc_size(1);
186 * Try to optimize malloc(..., ..., M_ZERO) allocations by doing zeroing in
187 * place if the size is known at compilation time.
189 * Passing the flag down requires malloc to blindly zero the entire object.
190 * In practice a lot of the zeroing can be avoided if most of the object
191 * gets explicitly initialized after the allocation. Letting the compiler
192 * zero in place gives it the opportunity to take advantage of this state.
194 * Note that the operation is only applicable if both flags and size are
195 * known at compilation time. If M_ZERO is passed but M_WAITOK is not, the
196 * allocation can fail and a NULL check is needed. However, if M_WAITOK is
197 * passed we know the allocation must succeed and the check can be elided.
199 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
200 * if (((flags) & M_WAITOK) != 0 || _malloc_item != NULL)
201 * bzero(_malloc_item, _size);
203 * If the flag is set, the compiler knows the left side is always true,
204 * therefore the entire statement is true and the callsite is:
206 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
207 * bzero(_malloc_item, _size);
209 * If the flag is not set, the compiler knows the left size is always false
210 * and the NULL check is needed, therefore the callsite is:
212 * _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
213 * if (_malloc_item != NULL)
214 * bzero(_malloc_item, _size);
216 * The implementation is a macro because of what appears to be a clang 6 bug:
217 * an inline function variant ended up being compiled to a mere malloc call
218 * regardless of argument. gcc generates expected code (like the above).
220 #define malloc(size, type, flags) ({ \
221 void *_malloc_item; \
222 size_t _size = (size); \
223 if (__builtin_constant_p(size) && __builtin_constant_p(flags) &&\
224 ((flags) & M_ZERO) != 0) { \
225 _malloc_item = malloc(_size, type, (flags) &~ M_ZERO); \
226 if (((flags) & M_WAITOK) != 0 || \
227 __predict_true(_malloc_item != NULL)) \
228 bzero(_malloc_item, _size); \
230 _malloc_item = malloc(_size, type, flags); \
235 void *malloc_domainset(size_t size, struct malloc_type *type,
236 struct domainset *ds, int flags) __malloc_like __result_use_check
238 void *mallocarray(size_t nmemb, size_t size, struct malloc_type *type,
239 int flags) __malloc_like __result_use_check
241 void malloc_init(void *);
242 int malloc_last_fail(void);
243 void malloc_type_allocated(struct malloc_type *type, unsigned long size);
244 void malloc_type_freed(struct malloc_type *type, unsigned long size);
245 void malloc_type_list(malloc_type_list_func_t *, void *);
246 void malloc_uninit(void *);
247 void *realloc(void *addr, size_t size, struct malloc_type *type, int flags)
248 __result_use_check __alloc_size(2);
249 void *reallocf(void *addr, size_t size, struct malloc_type *type, int flags)
250 __result_use_check __alloc_size(2);
252 struct malloc_type *malloc_desc2type(const char *desc);
255 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
256 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
258 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 8 / 2))
260 WOULD_OVERFLOW(size_t nmemb, size_t size)
263 return ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
264 nmemb > 0 && __SIZE_T_MAX / nmemb < size);
266 #undef MUL_NO_OVERFLOW
269 #endif /* !_SYS_MALLOC_H_ */