1 /*
2 A version of malloc/free/realloc written by Doug Lea and released to the
3 public domain. Send questions/comments/complaints/performance data
4 to dl@cs.oswego.edu
5
6 * VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
7
8 Note: There may be an updated version of this malloc obtainable at
9 ftp://g.oswego.edu/pub/misc/malloc.c
10 Check before installing!
11
12 * Why use this malloc?
13
14 This is not the fastest, most space-conserving, most portable, or
15 most tunable malloc ever written. However it is among the fastest
16 while also being among the most space-conserving, portable and tunable.
17 Consistent balance across these factors results in a good general-purpose
18 allocator. For a high-level description, see
19 http://g.oswego.edu/dl/html/malloc.html
20
21 * Synopsis of public routines
22
23 (Much fuller descriptions are contained in the program documentation below.)
24
25 malloc(size_t n);
26 Return a pointer to a newly allocated chunk of at least n bytes, or null
27 if no space is available.
28 free(Void_t* p);
29 Release the chunk of memory pointed to by p, or no effect if p is null.
30 realloc(Void_t* p, size_t n);
31 Return a pointer to a chunk of size n that contains the same data
32 as does chunk p up to the minimum of (n, p's size) bytes, or null
33 if no space is available. The returned pointer may or may not be
34 the same as p. If p is null, equivalent to malloc. Unless the
35 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
36 size argument of zero (re)allocates a minimum-sized chunk.
37 memalign(size_t alignment, size_t n);
38 Return a pointer to a newly allocated chunk of n bytes, aligned
39 in accord with the alignment argument, which must be a power of
40 two.
41 valloc(size_t n);
42 Equivalent to memalign(pagesize, n), where pagesize is the page
43 size of the system (or as near to this as can be figured out from
44 all the includes/defines below.)
45 pvalloc(size_t n);
46 Equivalent to valloc(minimum-page-that-holds(n)), that is,
47 round up n to nearest pagesize.
48 calloc(size_t unit, size_t quantity);
49 Returns a pointer to quantity * unit bytes, with all locations
50 set to zero.
51 cfree(Void_t* p);
52 Equivalent to free(p).
53 malloc_trim(size_t pad);
54 Release all but pad bytes of freed top-most memory back
55 to the system. Return 1 if successful, else 0.
56 malloc_usable_size(Void_t* p);
57 Report the number usable allocated bytes associated with allocated
58 chunk p. This may or may not report more bytes than were requested,
59 due to alignment and minimum size constraints.
60 malloc_stats();
61 Prints brief summary statistics on stderr.
62 mallinfo()
63 Returns (by copy) a struct containing various summary statistics.
64 mallopt(int parameter_number, int parameter_value)
65 Changes one of the tunable parameters described below. Returns
66 1 if successful in changing the parameter, else 0.
67
68 * Vital statistics:
69
70 Alignment: 8-byte
71 8 byte alignment is currently hardwired into the design. This
72 seems to suffice for all current machines and C compilers.
73
74 Assumed pointer representation: 4 or 8 bytes
75 Code for 8-byte pointers is untested by me but has worked
76 reliably by Wolfram Gloger, who contributed most of the
77 changes supporting this.
78
79 Assumed size_t representation: 4 or 8 bytes
80 Note that size_t is allowed to be 4 bytes even if pointers are 8.
81
82 Minimum overhead per allocated chunk: 4 or 8 bytes
83 Each malloced chunk has a hidden overhead of 4 bytes holding size
84 and status information.
85
86 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
87 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
88
89 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
90 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
91 needed; 4 (8) for a trailing size field
92 and 8 (16) bytes for free list pointers. Thus, the minimum
93 allocatable size is 16/24/32 bytes.
94
95 Even a request for zero bytes (i.e., malloc(0)) returns a
96 pointer to something of the minimum allocatable size.
97
98 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
99 8-byte size_t: 2^63 - 16 bytes
100
101 It is assumed that (possibly signed) size_t bit values suffice to
102 represent chunk sizes. `Possibly signed' is due to the fact
103 that `size_t' may be defined on a system as either a signed or
104 an unsigned type. To be conservative, values that would appear
105 as negative numbers are avoided.
106 Requests for sizes with a negative sign bit when the request
107 size is treaded as a long will return null.
108
109 Maximum overhead wastage per allocated chunk: normally 15 bytes
110
111 Alignnment demands, plus the minimum allocatable size restriction
112 make the normal worst-case wastage 15 bytes (i.e., up to 15
113 more bytes will be allocated than were requested in malloc), with
114 two exceptions:
115 1. Because requests for zero bytes allocate non-zero space,
116 the worst case wastage for a request of zero bytes is 24 bytes.
117 2. For requests >= mmap_threshold that are serviced via
118 mmap(), the worst case wastage is 8 bytes plus the remainder
119 from a system page (the minimal mmap unit); typically 4096 bytes.
120
121 * Limitations
122
123 Here are some features that are NOT currently supported
124
125 * No user-definable hooks for callbacks and the like.
126 * No automated mechanism for fully checking that all accesses
127 to malloced memory stay within their bounds.
128 * No support for compaction.
129
130 * Synopsis of compile-time options:
131
132 People have reported using previous versions of this malloc on all
133 versions of Unix, sometimes by tweaking some of the defines
134 below. It has been tested most extensively on Solaris and
135 Linux. It is also reported to work on WIN32 platforms.
136 People have also reported adapting this malloc for use in
137 stand-alone embedded systems.
138
139 The implementation is in straight, hand-tuned ANSI C. Among other
140 consequences, it uses a lot of macros. Because of this, to be at
141 all usable, this code should be compiled using an optimizing compiler
142 (for example gcc -O2) that can simplify expressions and control
143 paths.
144
145 __STD_C (default: derived from C compiler defines)
146 Nonzero if using ANSI-standard C compiler, a C++ compiler, or
147 a C compiler sufficiently close to ANSI to get away with it.
148 DEBUG (default: NOT defined)
149 Define to enable debugging. Adds fairly extensive assertion-based
150 checking to help track down memory errors, but noticeably slows down
151 execution.
152 REALLOC_ZERO_BYTES_FREES (default: NOT defined)
153 Define this if you think that realloc(p, 0) should be equivalent
154 to free(p). Otherwise, since malloc returns a unique pointer for
155 malloc(0), so does realloc(p, 0).
156 HAVE_MEMCPY (default: defined)
157 Define if you are not otherwise using ANSI STD C, but still
158 have memcpy and memset in your C library and want to use them.
159 Otherwise, simple internal versions are supplied.
160 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
161 Define as 1 if you want the C library versions of memset and
162 memcpy called in realloc and calloc (otherwise macro versions are used).
163 At least on some platforms, the simple macro versions usually
164 outperform libc versions.
165 HAVE_MMAP (default: defined as 1)
166 Define to non-zero to optionally make malloc() use mmap() to
167 allocate very large blocks.
168 HAVE_MREMAP (default: defined as 0 unless Linux libc set)
169 Define to non-zero to optionally make realloc() use mremap() to
170 reallocate very large blocks.
171 malloc_getpagesize (default: derived from system #includes)
172 Either a constant or routine call returning the system page size.
173 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
174 Optionally define if you are on a system with a /usr/include/malloc.h
175 that declares struct mallinfo. It is not at all necessary to
176 define this even if you do, but will ensure consistency.
177 INTERNAL_SIZE_T (default: size_t)
178 Define to a 32-bit type (probably `unsigned int') if you are on a
179 64-bit machine, yet do not want or need to allow malloc requests of
180 greater than 2^31 to be handled. This saves space, especially for
181 very small chunks.
182 INTERNAL_LINUX_C_LIB (default: NOT defined)
183 Defined only when compiled as part of Linux libc.
184 Also note that there is some odd internal name-mangling via defines
185 (for example, internally, `malloc' is named `mALLOc') needed
186 when compiling in this case. These look funny but don't otherwise
187 affect anything.
188 WIN32 (default: undefined)
189 Define this on MS win (95, nt) platforms to compile in sbrk emulation.
190 LACKS_UNISTD_H (default: undefined if not WIN32)
191 Define this if your system does not have a <unistd.h>.
192 LACKS_SYS_PARAM_H (default: undefined if not WIN32)
193 Define this if your system does not have a <sys/param.h>.
194 MORECORE (default: sbrk)
195 The name of the routine to call to obtain more memory from the system.
196 MORECORE_FAILURE (default: -1)
197 The value returned upon failure of MORECORE.
198 MORECORE_CLEARS (default 1)
199 true (1) if the routine mapped to MORECORE zeroes out memory (which
200 holds for sbrk).
201 DEFAULT_TRIM_THRESHOLD
202 DEFAULT_TOP_PAD
203 DEFAULT_MMAP_THRESHOLD
204 DEFAULT_MMAP_MAX
205 Default values of tunable parameters (described in detail below)
206 controlling interaction with host system routines (sbrk, mmap, etc).
207 These values may also be changed dynamically via mallopt(). The
208 preset defaults are those that give best performance for typical
209 programs/systems.
210 USE_DL_PREFIX (default: undefined)
211 Prefix all public routines with the string 'dl'. Useful to
212 quickly avoid procedure declaration conflicts and linker symbol
213 conflicts with existing memory allocation routines.
214
215
216 */
217
218
219 #ifndef __MALLOC_H__
220 #define __MALLOC_H__
221
222 /* Preliminaries */
223
224 #ifndef __STD_C
225 #ifdef __STDC__
226 #define __STD_C 1
227 #else
228 #if __cplusplus
229 #define __STD_C 1
230 #else
231 #define __STD_C 0
232 #endif /*__cplusplus*/
233 #endif /*__STDC__*/
234 #endif /*__STD_C*/
235
236 #ifndef Void_t
237 #if (__STD_C || defined(WIN32))
238 #define Void_t void
239 #else
240 #define Void_t char
241 #endif
242 #endif /*Void_t*/
243
244 #if __STD_C
245 #include <linux/stddef.h> /* for size_t */
246 #else
247 #include <sys/types.h>
248 #endif /* __STD_C */
249
250 #ifdef __cplusplus
251 extern "C" {
252 #endif
253
254 #if 0 /* not for U-Boot */
255 #include <stdio.h> /* needed for malloc_stats */
256 #endif
257
258
259 /*
260 Compile-time options
261 */
262
263
264 /*
265 Debugging:
266
267 Because freed chunks may be overwritten with link fields, this
268 malloc will often die when freed memory is overwritten by user
269 programs. This can be very effective (albeit in an annoying way)
270 in helping track down dangling pointers.
271
272 If you compile with -DDEBUG, a number of assertion checks are
273 enabled that will catch more memory errors. You probably won't be
274 able to make much sense of the actual assertion errors, but they
275 should help you locate incorrectly overwritten memory. The
276 checking is fairly extensive, and will slow down execution
277 noticeably. Calling malloc_stats or mallinfo with DEBUG set will
278 attempt to check every non-mmapped allocated and free chunk in the
279 course of computing the summmaries. (By nature, mmapped regions
280 cannot be checked very much automatically.)
281
282 Setting DEBUG may also be helpful if you are trying to modify
283 this code. The assertions in the check routines spell out in more
284 detail the assumptions and invariants underlying the algorithms.
285
286 */
287
288 /*
289 INTERNAL_SIZE_T is the word-size used for internal bookkeeping
290 of chunk sizes. On a 64-bit machine, you can reduce malloc
291 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
292 at the expense of not being able to handle requests greater than
293 2^31. This limitation is hardly ever a concern; you are encouraged
294 to set this. However, the default version is the same as size_t.
295 */
296
297 #ifndef INTERNAL_SIZE_T
298 #define INTERNAL_SIZE_T size_t
299 #endif
300
301 /*
302 REALLOC_ZERO_BYTES_FREES should be set if a call to
303 realloc with zero bytes should be the same as a call to free.
304 Some people think it should. Otherwise, since this malloc
305 returns a unique pointer for malloc(0), so does realloc(p, 0).
306 */
307
308
309 /* #define REALLOC_ZERO_BYTES_FREES */
310
311
312 /*
313 WIN32 causes an emulation of sbrk to be compiled in
314 mmap-based options are not currently supported in WIN32.
315 */
316
317 /* #define WIN32 */
318 #ifdef WIN32
319 #define MORECORE wsbrk
320 #define HAVE_MMAP 0
321
322 #define LACKS_UNISTD_H
323 #define LACKS_SYS_PARAM_H
324
325 /*
326 Include 'windows.h' to get the necessary declarations for the
327 Microsoft Visual C++ data structures and routines used in the 'sbrk'
328 emulation.
329
330 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
331 Visual C++ header files are included.
332 */
333 #define WIN32_LEAN_AND_MEAN
334 #include <windows.h>
335 #endif
336
337
338 /*
339 HAVE_MEMCPY should be defined if you are not otherwise using
340 ANSI STD C, but still have memcpy and memset in your C library
341 and want to use them in calloc and realloc. Otherwise simple
342 macro versions are defined here.
343
344 USE_MEMCPY should be defined as 1 if you actually want to
345 have memset and memcpy called. People report that the macro
346 versions are often enough faster than libc versions on many
347 systems that it is better to use them.
348
349 */
350
351 #define HAVE_MEMCPY
352
353 #ifndef USE_MEMCPY
354 #ifdef HAVE_MEMCPY
355 #define USE_MEMCPY 1
356 #else
357 #define USE_MEMCPY 0
358 #endif
359 #endif
360
361 #if (__STD_C || defined(HAVE_MEMCPY))
362
363 #if __STD_C
364 /* U-Boot defines memset() and memcpy in /include/linux/string.h
365 void* memset(void*, int, size_t);
366 void* memcpy(void*, const void*, size_t);
367 */
368 #include <linux/string.h>
369 #else
370 #ifdef WIN32
371 /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
372 /* 'windows.h' */
373 #else
374 Void_t* memset();
375 Void_t* memcpy();
376 #endif
377 #endif
378 #endif
379
380 #if USE_MEMCPY
381
382 /* The following macros are only invoked with (2n+1)-multiples of
383 INTERNAL_SIZE_T units, with a positive integer n. This is exploited
384 for fast inline execution when n is small. */
385
386 #define MALLOC_ZERO(charp, nbytes) \
387 do { \
388 INTERNAL_SIZE_T mzsz = (nbytes); \
389 if(mzsz <= 9*sizeof(mzsz)) { \
390 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
391 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
392 *mz++ = 0; \
393 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
394 *mz++ = 0; \
395 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
396 *mz++ = 0; }}} \
397 *mz++ = 0; \
398 *mz++ = 0; \
399 *mz = 0; \
400 } else memset((charp), 0, mzsz); \
401 } while(0)
402
403 #define MALLOC_COPY(dest,src,nbytes) \
404 do { \
405 INTERNAL_SIZE_T mcsz = (nbytes); \
406 if(mcsz <= 9*sizeof(mcsz)) { \
407 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
408 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
409 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
410 *mcdst++ = *mcsrc++; \
411 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
412 *mcdst++ = *mcsrc++; \
413 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
414 *mcdst++ = *mcsrc++; }}} \
415 *mcdst++ = *mcsrc++; \
416 *mcdst++ = *mcsrc++; \
417 *mcdst = *mcsrc ; \
418 } else memcpy(dest, src, mcsz); \
419 } while(0)
420
421 #else /* !USE_MEMCPY */
422
423 /* Use Duff's device for good zeroing/copying performance. */
424
425 #define MALLOC_ZERO(charp, nbytes) \
426 do { \
427 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
428 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
429 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
430 switch (mctmp) { \
431 case 0: for(;;) { *mzp++ = 0; \
432 case 7: *mzp++ = 0; \
433 case 6: *mzp++ = 0; \
434 case 5: *mzp++ = 0; \
435 case 4: *mzp++ = 0; \
436 case 3: *mzp++ = 0; \
437 case 2: *mzp++ = 0; \
438 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
439 } \
440 } while(0)
441
442 #define MALLOC_COPY(dest,src,nbytes) \
443 do { \
444 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
445 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
446 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
447 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
448 switch (mctmp) { \
449 case 0: for(;;) { *mcdst++ = *mcsrc++; \
450 case 7: *mcdst++ = *mcsrc++; \
451 case 6: *mcdst++ = *mcsrc++; \
452 case 5: *mcdst++ = *mcsrc++; \
453 case 4: *mcdst++ = *mcsrc++; \
454 case 3: *mcdst++ = *mcsrc++; \
455 case 2: *mcdst++ = *mcsrc++; \
456 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
457 } \
458 } while(0)
459
460 #endif
461
462
463 /*
464 Define HAVE_MMAP to optionally make malloc() use mmap() to
465 allocate very large blocks. These will be returned to the
466 operating system immediately after a free().
467 */
468
469 /***
470 #ifndef HAVE_MMAP
471 #define HAVE_MMAP 1
472 #endif
473 ***/
474 #undef HAVE_MMAP /* Not available for U-Boot */
475
476 /*
477 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
478 large blocks. This is currently only possible on Linux with
479 kernel versions newer than 1.3.77.
480 */
481
482 /***
483 #ifndef HAVE_MREMAP
484 #ifdef INTERNAL_LINUX_C_LIB
485 #define HAVE_MREMAP 1
486 #else
487 #define HAVE_MREMAP 0
488 #endif
489 #endif
490 ***/
491 #undef HAVE_MREMAP /* Not available for U-Boot */
492
493 #ifdef HAVE_MMAP
494
495 #include <unistd.h>
496 #include <fcntl.h>
497 #include <sys/mman.h>
498
499 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
500 #define MAP_ANONYMOUS MAP_ANON
501 #endif
502
503 #endif /* HAVE_MMAP */
504
505 /*
506 Access to system page size. To the extent possible, this malloc
507 manages memory from the system in page-size units.
508
509 The following mechanics for getpagesize were adapted from
510 bsd/gnu getpagesize.h
511 */
512
513 #define LACKS_UNISTD_H /* Shortcut for U-Boot */
514 #define malloc_getpagesize 4096
515
516 #ifndef LACKS_UNISTD_H
517 # include <unistd.h>
518 #endif
519
520 #ifndef malloc_getpagesize
521 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
522 # ifndef _SC_PAGE_SIZE
523 # define _SC_PAGE_SIZE _SC_PAGESIZE
524 # endif
525 # endif
526 # ifdef _SC_PAGE_SIZE
527 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
528 # else
529 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
530 extern size_t getpagesize();
531 # define malloc_getpagesize getpagesize()
532 # else
533 # ifdef WIN32
534 # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
535 # else
536 # ifndef LACKS_SYS_PARAM_H
537 # include <sys/param.h>
538 # endif
539 # ifdef EXEC_PAGESIZE
540 # define malloc_getpagesize EXEC_PAGESIZE
541 # else
542 # ifdef NBPG
543 # ifndef CLSIZE
544 # define malloc_getpagesize NBPG
545 # else
546 # define malloc_getpagesize (NBPG * CLSIZE)
547 # endif
548 # else
549 # ifdef NBPC
550 # define malloc_getpagesize NBPC
551 # else
552 # ifdef PAGESIZE
553 # define malloc_getpagesize PAGESIZE
554 # else
555 # define malloc_getpagesize (4096) /* just guess */
556 # endif
557 # endif
558 # endif
559 # endif
560 # endif
561 # endif
562 # endif
563 #endif
564
565
566 /*
567
568 This version of malloc supports the standard SVID/XPG mallinfo
569 routine that returns a struct containing the same kind of
570 information you can get from malloc_stats. It should work on
571 any SVID/XPG compliant system that has a /usr/include/malloc.h
572 defining struct mallinfo. (If you'd like to install such a thing
573 yourself, cut out the preliminary declarations as described above
574 and below and save them in a malloc.h file. But there's no
575 compelling reason to bother to do this.)
576
577 The main declaration needed is the mallinfo struct that is returned
578 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
579 bunch of fields, most of which are not even meaningful in this
580 version of malloc. Some of these fields are are instead filled by
581 mallinfo() with other numbers that might possibly be of interest.
582
583 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
584 /usr/include/malloc.h file that includes a declaration of struct
585 mallinfo. If so, it is included; else an SVID2/XPG2 compliant
586 version is declared below. These must be precisely the same for
587 mallinfo() to work.
588
589 */
590
591 /* #define HAVE_USR_INCLUDE_MALLOC_H */
592
593 #ifdef HAVE_USR_INCLUDE_MALLOC_H
594 #include "/usr/include/malloc.h"
595 #else
596
597 /* SVID2/XPG mallinfo structure */
598
599 struct mallinfo {
600 int arena; /* total space allocated from system */
601 int ordblks; /* number of non-inuse chunks */
602 int smblks; /* unused -- always zero */
603 int hblks; /* number of mmapped regions */
604 int hblkhd; /* total space in mmapped regions */
605 int usmblks; /* unused -- always zero */
606 int fsmblks; /* unused -- always zero */
607 int uordblks; /* total allocated space */
608 int fordblks; /* total non-inuse space */
609 int keepcost; /* top-most, releasable (via malloc_trim) space */
610 };
611
612 /* SVID2/XPG mallopt options */
613
614 #define M_MXFAST 1 /* UNUSED in this malloc */
615 #define M_NLBLKS 2 /* UNUSED in this malloc */
616 #define M_GRAIN 3 /* UNUSED in this malloc */
617 #define M_KEEP 4 /* UNUSED in this malloc */
618
619 #endif
620
621 /* mallopt options that actually do something */
622
623 #define M_TRIM_THRESHOLD -1
624 #define M_TOP_PAD -2
625 #define M_MMAP_THRESHOLD -3
626 #define M_MMAP_MAX -4
627
628
629 #ifndef DEFAULT_TRIM_THRESHOLD
630 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
631 #endif
632
633 /*
634 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
635 to keep before releasing via malloc_trim in free().
636
637 Automatic trimming is mainly useful in long-lived programs.
638 Because trimming via sbrk can be slow on some systems, and can
639 sometimes be wasteful (in cases where programs immediately
640 afterward allocate more large chunks) the value should be high
641 enough so that your overall system performance would improve by
642 releasing.
643
644 The trim threshold and the mmap control parameters (see below)
645 can be traded off with one another. Trimming and mmapping are
646 two different ways of releasing unused memory back to the
647 system. Between these two, it is often possible to keep
648 system-level demands of a long-lived program down to a bare
649 minimum. For example, in one test suite of sessions measuring
650 the XF86 X server on Linux, using a trim threshold of 128K and a
651 mmap threshold of 192K led to near-minimal long term resource
652 consumption.
653
654 If you are using this malloc in a long-lived program, it should
655 pay to experiment with these values. As a rough guide, you
656 might set to a value close to the average size of a process
657 (program) running on your system. Releasing this much memory
658 would allow such a process to run in memory. Generally, it's
659 worth it to tune for trimming rather tham memory mapping when a
660 program undergoes phases where several large chunks are
661 allocated and released in ways that can reuse each other's
662 storage, perhaps mixed with phases where there are no such
663 chunks at all. And in well-behaved long-lived programs,
664 controlling release of large blocks via trimming versus mapping
665 is usually faster.
666
667 However, in most programs, these parameters serve mainly as
668 protection against the system-level effects of carrying around
669 massive amounts of unneeded memory. Since frequent calls to
670 sbrk, mmap, and munmap otherwise degrade performance, the default
671 parameters are set to relatively high values that serve only as
672 safeguards.
673
674 The default trim value is high enough to cause trimming only in
675 fairly extreme (by current memory consumption standards) cases.
676 It must be greater than page size to have any useful effect. To
677 disable trimming completely, you can set to (unsigned long)(-1);
678
679
680 */
681
682
683 #ifndef DEFAULT_TOP_PAD
684 #define DEFAULT_TOP_PAD (0)
685 #endif
686
687 /*
688 M_TOP_PAD is the amount of extra `padding' space to allocate or
689 retain whenever sbrk is called. It is used in two ways internally:
690
691 * When sbrk is called to extend the top of the arena to satisfy
692 a new malloc request, this much padding is added to the sbrk
693 request.
694
695 * When malloc_trim is called automatically from free(),
696 it is used as the `pad' argument.
697
698 In both cases, the actual amount of padding is rounded
699 so that the end of the arena is always a system page boundary.
700
701 The main reason for using padding is to avoid calling sbrk so
702 often. Having even a small pad greatly reduces the likelihood
703 that nearly every malloc request during program start-up (or
704 after trimming) will invoke sbrk, which needlessly wastes
705 time.
706
707 Automatic rounding-up to page-size units is normally sufficient
708 to avoid measurable overhead, so the default is 0. However, in
709 systems where sbrk is relatively slow, it can pay to increase
710 this value, at the expense of carrying around more memory than
711 the program needs.
712
713 */
714
715
716 #ifndef DEFAULT_MMAP_THRESHOLD
717 #define DEFAULT_MMAP_THRESHOLD (128 * 1024)
718 #endif
719
720 /*
721
722 M_MMAP_THRESHOLD is the request size threshold for using mmap()
723 to service a request. Requests of at least this size that cannot
724 be allocated using already-existing space will be serviced via mmap.
725 (If enough normal freed space already exists it is used instead.)
726
727 Using mmap segregates relatively large chunks of memory so that
728 they can be individually obtained and released from the host
729 system. A request serviced through mmap is never reused by any
730 other request (at least not directly; the system may just so
731 happen to remap successive requests to the same locations).
732
733 Segregating space in this way has the benefit that mmapped space
734 can ALWAYS be individually released back to the system, which
735 helps keep the system level memory demands of a long-lived
736 program low. Mapped memory can never become `locked' between
737 other chunks, as can happen with normally allocated chunks, which
738 menas that even trimming via malloc_trim would not release them.
739
740 However, it has the disadvantages that:
741
742 1. The space cannot be reclaimed, consolidated, and then
743 used to service later requests, as happens with normal chunks.
744 2. It can lead to more wastage because of mmap page alignment
745 requirements
746 3. It causes malloc performance to be more dependent on host
747 system memory management support routines which may vary in
748 implementation quality and may impose arbitrary
749 limitations. Generally, servicing a request via normal
750 malloc steps is faster than going through a system's mmap.
751
752 All together, these considerations should lead you to use mmap
753 only for relatively large requests.
754
755
756 */
757
758
759 #ifndef DEFAULT_MMAP_MAX
760 #ifdef HAVE_MMAP
761 #define DEFAULT_MMAP_MAX (64)
762 #else
763 #define DEFAULT_MMAP_MAX (0)
764 #endif
765 #endif
766
767 /*
768 M_MMAP_MAX is the maximum number of requests to simultaneously
769 service using mmap. This parameter exists because:
770
771 1. Some systems have a limited number of internal tables for
772 use by mmap.
773 2. In most systems, overreliance on mmap can degrade overall
774 performance.
775 3. If a program allocates many large regions, it is probably
776 better off using normal sbrk-based allocation routines that
777 can reclaim and reallocate normal heap memory. Using a
778 small value allows transition into this mode after the
779 first few allocations.
780
781 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
782 the default value is 0, and attempts to set it to non-zero values
783 in mallopt will fail.
784 */
785
786
787 /*
788 USE_DL_PREFIX will prefix all public routines with the string 'dl'.
789 Useful to quickly avoid procedure declaration conflicts and linker
790 symbol conflicts with existing memory allocation routines.
791
792 */
793
794 /*
795 * Rename the U-Boot alloc functions so that sandbox can still use the system
796 * ones
797 */
798 #ifdef CONFIG_SANDBOX
799 #define USE_DL_PREFIX
800 #endif
801
802 /*
803
804 Special defines for linux libc
805
806 Except when compiled using these special defines for Linux libc
807 using weak aliases, this malloc is NOT designed to work in
808 multithreaded applications. No semaphores or other concurrency
809 control are provided to ensure that multiple malloc or free calls
810 don't run at the same time, which could be disasterous. A single
811 semaphore could be used across malloc, realloc, and free (which is
812 essentially the effect of the linux weak alias approach). It would
813 be hard to obtain finer granularity.
814
815 */
816
817
818 #ifdef INTERNAL_LINUX_C_LIB
819
820 #if __STD_C
821
822 Void_t * __default_morecore_init (ptrdiff_t);
823 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
824
825 #else
826
827 Void_t * __default_morecore_init ();
828 Void_t *(*__morecore)() = __default_morecore_init;
829
830 #endif
831
832 #define MORECORE (*__morecore)
833 #define MORECORE_FAILURE 0
834 #define MORECORE_CLEARS 1
835
836 #else /* INTERNAL_LINUX_C_LIB */
837
838 #if __STD_C
839 extern Void_t* sbrk(ptrdiff_t);
840 #else
841 extern Void_t* sbrk();
842 #endif
843
844 #ifndef MORECORE
845 #define MORECORE sbrk
846 #endif
847
848 #ifndef MORECORE_FAILURE
849 #define MORECORE_FAILURE -1
850 #endif
851
852 #ifndef MORECORE_CLEARS
853 #define MORECORE_CLEARS 1
854 #endif
855
856 #endif /* INTERNAL_LINUX_C_LIB */
857
858 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
859
860 #define cALLOc __libc_calloc
861 #define fREe __libc_free
862 #define mALLOc __libc_malloc
863 #define mEMALIGn __libc_memalign
864 #define rEALLOc __libc_realloc
865 #define vALLOc __libc_valloc
866 #define pvALLOc __libc_pvalloc
867 #define mALLINFo __libc_mallinfo
868 #define mALLOPt __libc_mallopt
869
870 #pragma weak calloc = __libc_calloc
871 #pragma weak free = __libc_free
872 #pragma weak cfree = __libc_free
873 #pragma weak malloc = __libc_malloc
874 #pragma weak memalign = __libc_memalign
875 #pragma weak realloc = __libc_realloc
876 #pragma weak valloc = __libc_valloc
877 #pragma weak pvalloc = __libc_pvalloc
878 #pragma weak mallinfo = __libc_mallinfo
879 #pragma weak mallopt = __libc_mallopt
880
881 #else
882
883 #if CONFIG_IS_ENABLED(SYS_MALLOC_SIMPLE)
884 #define malloc malloc_simple
885 #define realloc realloc_simple
886 #define memalign memalign_simple
free(void * ptr)887 static inline void free(void *ptr) {}
888 void *calloc(size_t nmemb, size_t size);
889 void *realloc_simple(void *ptr, size_t size);
890 void malloc_simple_info(void);
891 #else
892
893 # ifdef USE_DL_PREFIX
894 # define cALLOc dlcalloc
895 # define fREe dlfree
896 # define mALLOc dlmalloc
897 # define mEMALIGn dlmemalign
898 # define rEALLOc dlrealloc
899 # define vALLOc dlvalloc
900 # define pvALLOc dlpvalloc
901 # define mALLINFo dlmallinfo
902 # define mALLOPt dlmallopt
903
904 /* Ensure that U-Boot actually uses these too */
905 #define calloc dlcalloc
906 #define free(ptr) dlfree(ptr)
907 #define malloc(x) dlmalloc(x)
908 #define memalign dlmemalign
909 #define realloc dlrealloc
910 #define valloc dlvalloc
911 #define pvalloc dlpvalloc
912 #define mallinfo() dlmallinfo()
913 #define mallopt dlmallopt
914 #define malloc_trim dlmalloc_trim
915 #define malloc_usable_size dlmalloc_usable_size
916 #define malloc_stats dlmalloc_stats
917
918 # else /* USE_DL_PREFIX */
919 # define cALLOc calloc
920 # define fREe free
921 # define mALLOc malloc
922 # define mEMALIGn memalign
923 # define rEALLOc realloc
924 # define vALLOc valloc
925 # define pvALLOc pvalloc
926 # define mALLINFo mallinfo
927 # define mALLOPt mallopt
928 # endif /* USE_DL_PREFIX */
929
930 #endif
931
932 /* Set up pre-relocation malloc() ready for use */
933 int initf_malloc(void);
934
935 /* Public routines */
936
937 /* Simple versions which can be used when space is tight */
938 void *malloc_simple(size_t size);
939 void *memalign_simple(size_t alignment, size_t bytes);
940
941 #pragma GCC visibility push(hidden)
942 # if __STD_C
943
944 Void_t* mALLOc(size_t);
945 void fREe(Void_t*);
946 Void_t* rEALLOc(Void_t*, size_t);
947 Void_t* mEMALIGn(size_t, size_t);
948 Void_t* vALLOc(size_t);
949 Void_t* pvALLOc(size_t);
950 Void_t* cALLOc(size_t, size_t);
951 void cfree(Void_t*);
952 int malloc_trim(size_t);
953 size_t malloc_usable_size(Void_t*);
954 void malloc_stats(void);
955 int mALLOPt(int, int);
956 struct mallinfo mALLINFo(void);
957 # else
958 Void_t* mALLOc();
959 void fREe();
960 Void_t* rEALLOc();
961 Void_t* mEMALIGn();
962 Void_t* vALLOc();
963 Void_t* pvALLOc();
964 Void_t* cALLOc();
965 void cfree();
966 int malloc_trim();
967 size_t malloc_usable_size();
968 void malloc_stats();
969 int mALLOPt();
970 struct mallinfo mALLINFo();
971 # endif
972 #endif
973 #pragma GCC visibility pop
974
975 /*
976 * Begin and End of memory area for malloc(), and current "brk"
977 */
978 extern ulong mem_malloc_start;
979 extern ulong mem_malloc_end;
980 extern ulong mem_malloc_brk;
981
982 void mem_malloc_init(ulong start, ulong size);
983
984 #ifdef __cplusplus
985 }; /* end of extern "C" */
986 #endif
987
988 #endif /* __MALLOC_H__ */
989