The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/malloc.h

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1987, 1993
    5  *      The Regents of the University of California.
    6  * Copyright (c) 2005, 2009 Robert N. M. Watson
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      @(#)malloc.h    8.5 (Berkeley) 5/3/95
   34  * $FreeBSD$
   35  */
   36 
   37 #ifndef _SYS_MALLOC_H_
   38 #define _SYS_MALLOC_H_
   39 
   40 #ifndef _STANDALONE
   41 #include <sys/param.h>
   42 #ifdef _KERNEL
   43 #include <sys/systm.h>
   44 #endif
   45 #include <sys/queue.h>
   46 #include <sys/_lock.h>
   47 #include <sys/_mutex.h>
   48 #include <machine/_limits.h>
   49 
   50 #define MINALLOCSIZE    UMA_SMALLEST_UNIT
   51 
   52 /*
   53  * Flags to memory allocation functions.
   54  */
   55 #define M_NOWAIT        0x0001          /* do not block */
   56 #define M_WAITOK        0x0002          /* ok to block */
   57 #define M_NORECLAIM     0x0080          /* do not reclaim after failure */
   58 #define M_ZERO          0x0100          /* bzero the allocation */
   59 #define M_NOVM          0x0200          /* don't ask VM for pages */
   60 #define M_USE_RESERVE   0x0400          /* can alloc out of reserve memory */
   61 #define M_NODUMP        0x0800          /* don't dump pages in this allocation */
   62 #define M_FIRSTFIT      0x1000          /* only for vmem, fast fit */
   63 #define M_BESTFIT       0x2000          /* only for vmem, low fragmentation */
   64 #define M_EXEC          0x4000          /* allocate executable space */
   65 #define M_NEXTFIT       0x8000          /* only for vmem, follow cursor */
   66 
   67 #define M_VERSION       2020110501
   68 
   69 /*
   70  * Two malloc type structures are present: malloc_type, which is used by a
   71  * type owner to declare the type, and malloc_type_internal, which holds
   72  * malloc-owned statistics and other ABI-sensitive fields, such as the set of
   73  * malloc statistics indexed by the compile-time MAXCPU constant.
   74  * Applications should avoid introducing dependence on the allocator private
   75  * data layout and size.
   76  *
   77  * The malloc_type ks_next field is protected by malloc_mtx.  Other fields in
   78  * malloc_type are static after initialization so unsynchronized.
   79  *
   80  * Statistics in malloc_type_stats are written only when holding a critical
   81  * section and running on the CPU associated with the index into the stat
   82  * array, but read lock-free resulting in possible (minor) races, which the
   83  * monitoring app should take into account.
   84  */
   85 struct malloc_type_stats {
   86         uint64_t        mts_memalloced; /* Bytes allocated on CPU. */
   87         uint64_t        mts_memfreed;   /* Bytes freed on CPU. */
   88         uint64_t        mts_numallocs;  /* Number of allocates on CPU. */
   89         uint64_t        mts_numfrees;   /* number of frees on CPU. */
   90         uint64_t        mts_size;       /* Bitmask of sizes allocated on CPU. */
   91         uint64_t        _mts_reserved1; /* Reserved field. */
   92         uint64_t        _mts_reserved2; /* Reserved field. */
   93         uint64_t        _mts_reserved3; /* Reserved field. */
   94 };
   95 
   96 _Static_assert(sizeof(struct malloc_type_stats) == 64,
   97     "allocations come from pcpu_zone_64");
   98 
   99 /*
  100  * Index definitions for the mti_probes[] array.
  101  */
  102 #define DTMALLOC_PROBE_MALLOC           0
  103 #define DTMALLOC_PROBE_FREE             1
  104 #define DTMALLOC_PROBE_MAX              2
  105 
  106 struct malloc_type_internal {
  107         uint32_t        mti_probes[DTMALLOC_PROBE_MAX];
  108                                         /* DTrace probe ID array. */
  109         u_char          mti_zone;
  110         struct malloc_type_stats        *mti_stats;
  111         u_long          mti_spare[8];
  112 };
  113 
  114 /*
  115  * Public data structure describing a malloc type.
  116  */
  117 struct malloc_type {
  118         struct malloc_type *ks_next;    /* Next in global chain. */
  119         u_long           ks_version;    /* Detect programmer error. */
  120         const char      *ks_shortdesc;  /* Printable type name. */
  121         struct malloc_type_internal ks_mti;
  122 };
  123 
  124 /*
  125  * Statistics structure headers for user space.  The kern.malloc sysctl
  126  * exposes a structure stream consisting of a stream header, then a series of
  127  * malloc type headers and statistics structures (quantity maxcpus).  For
  128  * convenience, the kernel will provide the current value of maxcpus at the
  129  * head of the stream.
  130  */
  131 #define MALLOC_TYPE_STREAM_VERSION      0x00000001
  132 struct malloc_type_stream_header {
  133         uint32_t        mtsh_version;   /* Stream format version. */
  134         uint32_t        mtsh_maxcpus;   /* Value of MAXCPU for stream. */
  135         uint32_t        mtsh_count;     /* Number of records. */
  136         uint32_t        _mtsh_pad;      /* Pad/reserved field. */
  137 };
  138 
  139 #define MALLOC_MAX_NAME 32
  140 struct malloc_type_header {
  141         char                            mth_name[MALLOC_MAX_NAME];
  142 };
  143 
  144 #ifdef _KERNEL
  145 #define MALLOC_DEFINE(type, shortdesc, longdesc)                        \
  146         struct malloc_type type[1] = {                                  \
  147                 {                                                       \
  148                         .ks_next = NULL,                                \
  149                         .ks_version = M_VERSION,                        \
  150                         .ks_shortdesc = shortdesc,                      \
  151                 }                                                       \
  152         };                                                              \
  153         SYSINIT(type##_init, SI_SUB_KMEM, SI_ORDER_THIRD, malloc_init,  \
  154             type);                                                      \
  155         SYSUNINIT(type##_uninit, SI_SUB_KMEM, SI_ORDER_ANY,             \
  156             malloc_uninit, type)
  157 
  158 #define MALLOC_DECLARE(type) \
  159         extern struct malloc_type type[1]
  160 
  161 MALLOC_DECLARE(M_CACHE);
  162 MALLOC_DECLARE(M_DEVBUF);
  163 MALLOC_DECLARE(M_TEMP);
  164 
  165 /*
  166  * XXX this should be declared in <sys/uio.h>, but that tends to fail
  167  * because <sys/uio.h> is included in a header before the source file
  168  * has a chance to include <sys/malloc.h> to get MALLOC_DECLARE() defined.
  169  */
  170 MALLOC_DECLARE(M_IOV);
  171 
  172 struct domainset;
  173 extern struct mtx malloc_mtx;
  174 
  175 /*
  176  * Function type used when iterating over the list of malloc types.
  177  */
  178 typedef void malloc_type_list_func_t(struct malloc_type *, void *);
  179 
  180 void    contigfree(void *addr, unsigned long size, struct malloc_type *type);
  181 void    *contigmalloc(unsigned long size, struct malloc_type *type, int flags,
  182             vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
  183             vm_paddr_t boundary) __malloc_like __result_use_check
  184             __alloc_size(1) __alloc_align(6);
  185 void    *contigmalloc_domainset(unsigned long size, struct malloc_type *type,
  186             struct domainset *ds, int flags, vm_paddr_t low, vm_paddr_t high,
  187             unsigned long alignment, vm_paddr_t boundary)
  188             __malloc_like __result_use_check __alloc_size(1) __alloc_align(7);
  189 void    free(void *addr, struct malloc_type *type);
  190 void    zfree(void *addr, struct malloc_type *type);
  191 void    *malloc(size_t size, struct malloc_type *type, int flags) __malloc_like
  192             __result_use_check __alloc_size(1);
  193 /*
  194  * Try to optimize malloc(..., ..., M_ZERO) allocations by doing zeroing in
  195  * place if the size is known at compilation time.
  196  *
  197  * Passing the flag down requires malloc to blindly zero the entire object.
  198  * In practice a lot of the zeroing can be avoided if most of the object
  199  * gets explicitly initialized after the allocation. Letting the compiler
  200  * zero in place gives it the opportunity to take advantage of this state.
  201  *
  202  * Note that the operation is only applicable if both flags and size are
  203  * known at compilation time. If M_ZERO is passed but M_WAITOK is not, the
  204  * allocation can fail and a NULL check is needed. However, if M_WAITOK is
  205  * passed we know the allocation must succeed and the check can be elided.
  206  *
  207  *      _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
  208  *      if (((flags) & M_WAITOK) != 0 || _malloc_item != NULL)
  209  *              bzero(_malloc_item, _size);
  210  *
  211  * If the flag is set, the compiler knows the left side is always true,
  212  * therefore the entire statement is true and the callsite is:
  213  *
  214  *      _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
  215  *      bzero(_malloc_item, _size);
  216  *
  217  * If the flag is not set, the compiler knows the left size is always false
  218  * and the NULL check is needed, therefore the callsite is:
  219  *
  220  *      _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);
  221  *      if (_malloc_item != NULL)
  222  *              bzero(_malloc_item, _size);                     
  223  *
  224  * The implementation is a macro because of what appears to be a clang 6 bug:
  225  * an inline function variant ended up being compiled to a mere malloc call
  226  * regardless of argument. gcc generates expected code (like the above).
  227  */
  228 #define malloc(size, type, flags) ({                                    \
  229         void *_malloc_item;                                             \
  230         size_t _size = (size);                                          \
  231         if (__builtin_constant_p(size) && __builtin_constant_p(flags) &&\
  232             ((flags) & M_ZERO) != 0) {                                  \
  233                 _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);  \
  234                 if (((flags) & M_WAITOK) != 0 ||                        \
  235                     __predict_true(_malloc_item != NULL))               \
  236                         memset(_malloc_item, 0, _size);                 \
  237         } else {                                                        \
  238                 _malloc_item = malloc(_size, type, flags);              \
  239         }                                                               \
  240         _malloc_item;                                                   \
  241 })
  242 
  243 void    *malloc_domainset(size_t size, struct malloc_type *type,
  244             struct domainset *ds, int flags) __malloc_like __result_use_check
  245             __alloc_size(1);
  246 void    *mallocarray(size_t nmemb, size_t size, struct malloc_type *type,
  247             int flags) __malloc_like __result_use_check
  248             __alloc_size2(1, 2);
  249 void    *mallocarray_domainset(size_t nmemb, size_t size, struct malloc_type *type,
  250             struct domainset *ds, int flags) __malloc_like __result_use_check
  251             __alloc_size2(1, 2);
  252 void    *malloc_exec(size_t size, struct malloc_type *type, int flags) __malloc_like
  253             __result_use_check __alloc_size(1);
  254 void    *malloc_domainset_exec(size_t size, struct malloc_type *type,
  255             struct domainset *ds, int flags) __malloc_like __result_use_check
  256             __alloc_size(1);
  257 void    malloc_init(void *);
  258 void    malloc_type_allocated(struct malloc_type *type, unsigned long size);
  259 void    malloc_type_freed(struct malloc_type *type, unsigned long size);
  260 void    malloc_type_list(malloc_type_list_func_t *, void *);
  261 void    malloc_uninit(void *);
  262 size_t  malloc_size(size_t);
  263 size_t  malloc_usable_size(const void *);
  264 void    *realloc(void *addr, size_t size, struct malloc_type *type, int flags)
  265             __result_use_check __alloc_size(2);
  266 void    *reallocf(void *addr, size_t size, struct malloc_type *type, int flags)
  267             __result_use_check __alloc_size(2);
  268 void    *malloc_aligned(size_t size, size_t align, struct malloc_type *type,
  269             int flags) __malloc_like __result_use_check __alloc_size(1);
  270 void    *malloc_domainset_aligned(size_t size, size_t align,
  271             struct malloc_type *mtp, struct domainset *ds, int flags)
  272             __malloc_like __result_use_check __alloc_size(1);
  273 
  274 struct malloc_type *malloc_desc2type(const char *desc);
  275 
  276 /*
  277  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
  278  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
  279  */
  280 #define MUL_NO_OVERFLOW         (1UL << (sizeof(size_t) * 8 / 2))
  281 static inline bool
  282 WOULD_OVERFLOW(size_t nmemb, size_t size)
  283 {
  284 
  285         return ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
  286             nmemb > 0 && __SIZE_T_MAX / nmemb < size);
  287 }
  288 #undef MUL_NO_OVERFLOW
  289 #endif /* _KERNEL */
  290 
  291 #else
  292 /*
  293  * The native stand malloc / free interface we're mapping to
  294  */
  295 extern void Free(void *p, const char *file, int line);
  296 extern void *Malloc(size_t bytes, const char *file, int line);
  297 
  298 /*
  299  * Minimal standalone malloc implementation / environment. None of the
  300  * flags mean anything and there's no need declare malloc types.
  301  * Define the simple alloc / free routines in terms of Malloc and
  302  * Free. None of the kernel features that this stuff disables are needed.
  303  */
  304 #define M_WAITOK 1
  305 #define M_ZERO 0
  306 #define M_NOWAIT 2
  307 #define MALLOC_DECLARE(x)
  308 
  309 #define kmem_zalloc(size, flags) ({                                     \
  310         void *p = Malloc((size), __FILE__, __LINE__);                   \
  311         if (p == NULL && (flags &  M_WAITOK) != 0)                      \
  312                 panic("Could not malloc %zd bytes with M_WAITOK from %s line %d", \
  313                     (size_t)size, __FILE__, __LINE__);                  \
  314         p;                                                              \
  315 })
  316 
  317 #define kmem_free(p, size) Free(p, __FILE__, __LINE__)
  318 
  319 /*
  320  * ZFS mem.h define that's the OpenZFS porting layer way of saying
  321  * M_WAITOK. Given the above, it will also be a nop.
  322  */
  323 #define KM_SLEEP M_WAITOK
  324 #define KM_NOSLEEP M_NOWAIT
  325 #endif /* _STANDALONE */
  326 #endif /* !_SYS_MALLOC_H_ */

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