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_
41 #include <sys/param.h>
43 #include <sys/systm.h>
45 #include <sys/queue.h>
46 #include <sys/_lock.h>
47 #include <sys/_mutex.h>
48 #include <machine/_limits.h>
50 #define MINALLOCSIZE UMA_SMALLEST_UNIT
53 * Flags to memory allocation functions.
55 #define M_NOWAIT 0x0001 /* do not block */
56 #define M_WAITOK 0x0002 /* ok to block */
57 #define M_ZERO 0x0100 /* bzero the allocation */
58 #define M_NOVM 0x0200 /* don't ask VM for pages */
59 #define M_USE_RESERVE 0x0400 /* can alloc out of reserve memory */
60 #define M_NODUMP 0x0800 /* don't dump pages in this allocation */
61 #define M_FIRSTFIT 0x1000 /* only for vmem, fast fit */
62 #define M_BESTFIT 0x2000 /* only for vmem, low fragmentation */
63 #define M_EXEC 0x4000 /* allocate executable space */
64 #define M_NEXTFIT 0x8000 /* only for vmem, follow cursor */
66 #define M_VERSION 2020110501
69 * Two malloc type structures are present: malloc_type, which is used by a
70 * type owner to declare the type, and malloc_type_internal, which holds
71 * malloc-owned statistics and other ABI-sensitive fields, such as the set of
72 * malloc statistics indexed by the compile-time MAXCPU constant.
73 * Applications should avoid introducing dependence on the allocator private
74 * data layout and size.
76 * The malloc_type ks_next field is protected by malloc_mtx. Other fields in
77 * malloc_type are static after initialization so unsynchronized.
79 * Statistics in malloc_type_stats are written only when holding a critical
80 * section and running on the CPU associated with the index into the stat
81 * array, but read lock-free resulting in possible (minor) races, which the
82 * monitoring app should take into account.
84 struct malloc_type_stats {
85 uint64_t mts_memalloced; /* Bytes allocated on CPU. */
86 uint64_t mts_memfreed; /* Bytes freed on CPU. */
87 uint64_t mts_numallocs; /* Number of allocates on CPU. */
88 uint64_t mts_numfrees; /* number of frees on CPU. */
89 uint64_t mts_size; /* Bitmask of sizes allocated on CPU. */
90 uint64_t _mts_reserved1; /* Reserved field. */
91 uint64_t _mts_reserved2; /* Reserved field. */
92 uint64_t _mts_reserved3; /* Reserved field. */
96 * Index definitions for the mti_probes[] array.
98 #define DTMALLOC_PROBE_MALLOC 0
99 #define DTMALLOC_PROBE_FREE 1
100 #define DTMALLOC_PROBE_MAX 2
102 struct malloc_type_internal {
103 uint32_t mti_probes[DTMALLOC_PROBE_MAX];
104 /* DTrace probe ID array. */
106 struct malloc_type_stats *mti_stats;
111 * Public data structure describing a malloc type.
114 struct malloc_type *ks_next; /* Next in global chain. */
115 u_long ks_version; /* Detect programmer error. */
116 const char *ks_shortdesc; /* Printable type name. */
117 struct malloc_type_internal ks_mti;
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] = { \
145 .ks_version = M_VERSION, \
146 .ks_shortdesc = shortdesc, \
150 SYSINIT(type##_init, SI_SUB_KMEM, SI_ORDER_THIRD, malloc_init, \
152 SYSUNINIT(type##_uninit, SI_SUB_KMEM, SI_ORDER_ANY, \
155 #define MALLOC_DECLARE(type) \
156 extern struct malloc_type type[1]
158 MALLOC_DECLARE(M_CACHE);
159 MALLOC_DECLARE(M_DEVBUF);
160 MALLOC_DECLARE(M_TEMP);
163 * XXX this should be declared in <sys/uio.h>, but that tends to fail
164 * because <sys/uio.h> is included in a header before the source file
165 * has a chance to include <sys/malloc.h> to get MALLOC_DECLARE() defined.
167 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_domainset(unsigned long size, struct malloc_type *type,
183 struct domainset *ds, 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(7);
186 void free(void *addr, struct malloc_type *type);
187 void zfree(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).
225 #define malloc(size, type, flags) ({ \
226 void *_malloc_item; \
227 size_t _size = (size); \
228 if (__builtin_constant_p(size) && __builtin_constant_p(flags) &&\
229 ((flags) & M_ZERO) != 0) { \
230 _malloc_item = malloc(_size, type, (flags) &~ M_ZERO); \
231 if (((flags) & M_WAITOK) != 0 || \
232 __predict_true(_malloc_item != NULL)) \
233 bzero(_malloc_item, _size); \
235 _malloc_item = malloc(_size, type, flags); \
240 void *malloc_domainset(size_t size, struct malloc_type *type,
241 struct domainset *ds, int flags) __malloc_like __result_use_check
243 void *mallocarray(size_t nmemb, size_t size, struct malloc_type *type,
244 int flags) __malloc_like __result_use_check
246 void *malloc_exec(size_t size, struct malloc_type *type, int flags) __malloc_like
247 __result_use_check __alloc_size(1);
248 void *malloc_domainset_exec(size_t size, struct malloc_type *type,
249 struct domainset *ds, int flags) __malloc_like __result_use_check
251 void malloc_init(void *);
252 int malloc_last_fail(void);
253 void malloc_type_allocated(struct malloc_type *type, unsigned long size);
254 void malloc_type_freed(struct malloc_type *type, unsigned long size);
255 void malloc_type_list(malloc_type_list_func_t *, void *);
256 void malloc_uninit(void *);
257 size_t malloc_size(size_t);
258 size_t malloc_usable_size(const void *);
259 void *realloc(void *addr, size_t size, struct malloc_type *type, int flags)
260 __result_use_check __alloc_size(2);
261 void *reallocf(void *addr, size_t size, struct malloc_type *type, int flags)
262 __result_use_check __alloc_size(2);
264 struct malloc_type *malloc_desc2type(const char *desc);
267 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
268 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
270 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 8 / 2))
272 WOULD_OVERFLOW(size_t nmemb, size_t size)
275 return ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
276 nmemb > 0 && __SIZE_T_MAX / nmemb < size);
278 #undef MUL_NO_OVERFLOW
283 * The native stand malloc / free interface we're mapping to
285 extern void Free(void *p, const char *file, int line);
286 extern void *Malloc(size_t bytes, const char *file, int line);
289 * Minimal standalone malloc implementation / environment. None of the
290 * flags mean anything and there's no need declare malloc types.
291 * Define the simple alloc / free routines in terms of Malloc and
292 * Free. None of the kernel features that this stuff disables are needed.
294 * XXX we are setting ourselves up for a potential crash if we can't allocate
295 * memory for a M_WAITOK call.
300 #define MALLOC_DECLARE(x)
302 #define kmem_zalloc(size, flags) Malloc((size), __FILE__, __LINE__)
303 #define kmem_free(p, size) Free(p, __FILE__, __LINE__)
306 * ZFS mem.h define that's the OpenZFS porting layer way of saying
307 * M_WAITOK. Given the above, it will also be a nop.
309 #define KM_SLEEP M_WAITOK
310 #endif /* _STANDALONE */
311 #endif /* !_SYS_MALLOC_H_ */