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