1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 This code is based on a version of malloc/free/realloc written by Doug Lea and
4 released to the public domain. Send questions/comments/complaints/performance
5 data to dl@cs.oswego.edu
6
7 * VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
8
9 Note: There may be an updated version of this malloc obtainable at
10 http://g.oswego.edu/pub/misc/malloc.c
11 Check before installing!
12
13 * Why use this malloc?
14
15 This is not the fastest, most space-conserving, most portable, or
16 most tunable malloc ever written. However it is among the fastest
17 while also being among the most space-conserving, portable and tunable.
18 Consistent balance across these factors results in a good general-purpose
19 allocator. For a high-level description, see
20 http://g.oswego.edu/dl/html/malloc.html
21
22 * Synopsis of public routines
23
24 (Much fuller descriptions are contained in the program documentation below.)
25
26 malloc(size_t n);
27 Return a pointer to a newly allocated chunk of at least n bytes, or null
28 if no space is available.
29 free(Void_t* p);
30 Release the chunk of memory pointed to by p, or no effect if p is null.
31 realloc(Void_t* p, size_t n);
32 Return a pointer to a chunk of size n that contains the same data
33 as does chunk p up to the minimum of (n, p's size) bytes, or null
34 if no space is available. The returned pointer may or may not be
35 the same as p. If p is null, equivalent to malloc. Unless the
36 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
37 size argument of zero (re)allocates a minimum-sized chunk.
38 memalign(size_t alignment, size_t n);
39 Return a pointer to a newly allocated chunk of n bytes, aligned
40 in accord with the alignment argument, which must be a power of
41 two.
42 valloc(size_t n);
43 Equivalent to memalign(pagesize, n), where pagesize is the page
44 size of the system (or as near to this as can be figured out from
45 all the includes/defines below.)
46 pvalloc(size_t n);
47 Equivalent to valloc(minimum-page-that-holds(n)), that is,
48 round up n to nearest pagesize.
49 calloc(size_t unit, size_t quantity);
50 Returns a pointer to quantity * unit bytes, with all locations
51 set to zero.
52 cfree(Void_t* p);
53 Equivalent to free(p).
54 malloc_trim(size_t pad);
55 Release all but pad bytes of freed top-most memory back
56 to the system. Return 1 if successful, else 0.
57 malloc_usable_size(Void_t* p);
58 Report the number usable allocated bytes associated with allocated
59 chunk p. This may or may not report more bytes than were requested,
60 due to alignment and minimum size constraints.
61 malloc_stats();
62 Prints brief summary statistics on stderr.
63 mallinfo()
64 Returns (by copy) a struct containing various summary statistics.
65 mallopt(int parameter_number, int parameter_value)
66 Changes one of the tunable parameters described below. Returns
67 1 if successful in changing the parameter, else 0.
68
69 * Vital statistics:
70
71 Alignment: 8-byte
72 8 byte alignment is currently hardwired into the design. This
73 seems to suffice for all current machines and C compilers.
74
75 Assumed pointer representation: 4 or 8 bytes
76 Code for 8-byte pointers is untested by me but has worked
77 reliably by Wolfram Gloger, who contributed most of the
78 changes supporting this.
79
80 Assumed size_t representation: 4 or 8 bytes
81 Note that size_t is allowed to be 4 bytes even if pointers are 8.
82
83 Minimum overhead per allocated chunk: 4 or 8 bytes
84 Each malloced chunk has a hidden overhead of 4 bytes holding size
85 and status information.
86
87 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
88 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
89
90 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
91 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
92 needed; 4 (8) for a trailing size field
93 and 8 (16) bytes for free list pointers. Thus, the minimum
94 allocatable size is 16/24/32 bytes.
95
96 Even a request for zero bytes (i.e., malloc(0)) returns a
97 pointer to something of the minimum allocatable size.
98
99 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
100 8-byte size_t: 2^63 - 16 bytes
101
102 It is assumed that (possibly signed) size_t bit values suffice to
103 represent chunk sizes. `Possibly signed' is due to the fact
104 that `size_t' may be defined on a system as either a signed or
105 an unsigned type. To be conservative, values that would appear
106 as negative numbers are avoided.
107 Requests for sizes with a negative sign bit when the request
108 size is treaded as a long will return null.
109
110 Maximum overhead wastage per allocated chunk: normally 15 bytes
111
112 Alignnment demands, plus the minimum allocatable size restriction
113 make the normal worst-case wastage 15 bytes (i.e., up to 15
114 more bytes will be allocated than were requested in malloc), with
115 two exceptions:
116 1. Because requests for zero bytes allocate non-zero space,
117 the worst case wastage for a request of zero bytes is 24 bytes.
118 2. For requests >= mmap_threshold that are serviced via
119 mmap(), the worst case wastage is 8 bytes plus the remainder
120 from a system page (the minimal mmap unit); typically 4096 bytes.
121
122 * Limitations
123
124 Here are some features that are NOT currently supported
125
126 * No user-definable hooks for callbacks and the like.
127 * No automated mechanism for fully checking that all accesses
128 to malloced memory stay within their bounds.
129 * No support for compaction.
130
131 * Synopsis of compile-time options:
132
133 People have reported using previous versions of this malloc on all
134 versions of Unix, sometimes by tweaking some of the defines
135 below. It has been tested most extensively on Solaris and
136 Linux. It is also reported to work on WIN32 platforms.
137 People have also reported adapting this malloc for use in
138 stand-alone embedded systems.
139
140 The implementation is in straight, hand-tuned ANSI C. Among other
141 consequences, it uses a lot of macros. Because of this, to be at
142 all usable, this code should be compiled using an optimizing compiler
143 (for example gcc -O2) that can simplify expressions and control
144 paths.
145
146 __STD_C (default: derived from C compiler defines)
147 Nonzero if using ANSI-standard C compiler, a C++ compiler, or
148 a C compiler sufficiently close to ANSI to get away with it.
149 DEBUG (default: NOT defined)
150 Define to enable debugging. Adds fairly extensive assertion-based
151 checking to help track down memory errors, but noticeably slows down
152 execution.
153 REALLOC_ZERO_BYTES_FREES (default: NOT defined)
154 Define this if you think that realloc(p, 0) should be equivalent
155 to free(p). Otherwise, since malloc returns a unique pointer for
156 malloc(0), so does realloc(p, 0).
157 HAVE_MEMCPY (default: defined)
158 Define if you are not otherwise using ANSI STD C, but still
159 have memcpy and memset in your C library and want to use them.
160 Otherwise, simple internal versions are supplied.
161 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
162 Define as 1 if you want the C library versions of memset and
163 memcpy called in realloc and calloc (otherwise macro versions are used).
164 At least on some platforms, the simple macro versions usually
165 outperform libc versions.
166 HAVE_MMAP (default: defined as 1)
167 Define to non-zero to optionally make malloc() use mmap() to
168 allocate very large blocks.
169 HAVE_MREMAP (default: defined as 0 unless Linux libc set)
170 Define to non-zero to optionally make realloc() use mremap() to
171 reallocate very large blocks.
172 malloc_getpagesize (default: derived from system #includes)
173 Either a constant or routine call returning the system page size.
174 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
175 Optionally define if you are on a system with a /usr/include/malloc.h
176 that declares struct mallinfo. It is not at all necessary to
177 define this even if you do, but will ensure consistency.
178 INTERNAL_SIZE_T (default: size_t)
179 Define to a 32-bit type (probably `unsigned int') if you are on a
180 64-bit machine, yet do not want or need to allow malloc requests of
181 greater than 2^31 to be handled. This saves space, especially for
182 very small chunks.
183 INTERNAL_LINUX_C_LIB (default: NOT defined)
184 Defined only when compiled as part of Linux libc.
185 Also note that there is some odd internal name-mangling via defines
186 (for example, internally, `malloc' is named `mALLOc') needed
187 when compiling in this case. These look funny but don't otherwise
188 affect anything.
189 WIN32 (default: undefined)
190 Define this on MS win (95, nt) platforms to compile in sbrk emulation.
191 LACKS_UNISTD_H (default: undefined if not WIN32)
192 Define this if your system does not have a <unistd.h>.
193 LACKS_SYS_PARAM_H (default: undefined if not WIN32)
194 Define this if your system does not have a <sys/param.h>.
195 MORECORE (default: sbrk)
196 The name of the routine to call to obtain more memory from the system.
197 MORECORE_FAILURE (default: -1)
198 The value returned upon failure of MORECORE.
199 MORECORE_CLEARS (default 1)
200 true (1) if the routine mapped to MORECORE zeroes out memory (which
201 holds for sbrk).
202 DEFAULT_TRIM_THRESHOLD
203 DEFAULT_TOP_PAD
204 DEFAULT_MMAP_THRESHOLD
205 DEFAULT_MMAP_MAX
206 Default values of tunable parameters (described in detail below)
207 controlling interaction with host system routines (sbrk, mmap, etc).
208 These values may also be changed dynamically via mallopt(). The
209 preset defaults are those that give best performance for typical
210 programs/systems.
211 USE_DL_PREFIX (default: undefined)
212 Prefix all public routines with the string 'dl'. Useful to
213 quickly avoid procedure declaration conflicts and linker symbol
214 conflicts with existing memory allocation routines.
215
216
217 */
218
219
220 #ifndef __MALLOC_H__
221 #define __MALLOC_H__
222
223 /* Preliminaries */
224
225 #ifndef __STD_C
226 #ifdef __STDC__
227 #define __STD_C 1
228 #else
229 #if __cplusplus
230 #define __STD_C 1
231 #else
232 #define __STD_C 0
233 #endif /*__cplusplus*/
234 #endif /*__STDC__*/
235 #endif /*__STD_C*/
236
237 #ifndef Void_t
238 #if (__STD_C || defined(WIN32))
239 #define Void_t void
240 #else
241 #define Void_t char
242 #endif
243 #endif /*Void_t*/
244
245 #if __STD_C
246 #include <linux/stddef.h> /* for size_t */
247 #else
248 #include <sys/types.h>
249 #endif /* __STD_C */
250
251 #ifdef __cplusplus
252 extern "C" {
253 #endif
254
255 #if 0 /* not for U-Boot */
256 #include <stdio.h> /* needed for malloc_stats */
257 #endif
258
259
260 /*
261 Compile-time options
262 */
263
264
265 /*
266 Debugging:
267
268 Because freed chunks may be overwritten with link fields, this
269 malloc will often die when freed memory is overwritten by user
270 programs. This can be very effective (albeit in an annoying way)
271 in helping track down dangling pointers.
272
273 If you compile with -DDEBUG, a number of assertion checks are
274 enabled that will catch more memory errors. You probably won't be
275 able to make much sense of the actual assertion errors, but they
276 should help you locate incorrectly overwritten memory. The
277 checking is fairly extensive, and will slow down execution
278 noticeably. Calling malloc_stats or mallinfo with DEBUG set will
279 attempt to check every non-mmapped allocated and free chunk in the
280 course of computing the summmaries. (By nature, mmapped regions
281 cannot be checked very much automatically.)
282
283 Setting DEBUG may also be helpful if you are trying to modify
284 this code. The assertions in the check routines spell out in more
285 detail the assumptions and invariants underlying the algorithms.
286
287 */
288
289 /*
290 INTERNAL_SIZE_T is the word-size used for internal bookkeeping
291 of chunk sizes. On a 64-bit machine, you can reduce malloc
292 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
293 at the expense of not being able to handle requests greater than
294 2^31. This limitation is hardly ever a concern; you are encouraged
295 to set this. However, the default version is the same as size_t.
296 */
297
298 #ifndef INTERNAL_SIZE_T
299 #define INTERNAL_SIZE_T size_t
300 #endif
301
302 /*
303 REALLOC_ZERO_BYTES_FREES should be set if a call to
304 realloc with zero bytes should be the same as a call to free.
305 Some people think it should. Otherwise, since this malloc
306 returns a unique pointer for malloc(0), so does realloc(p, 0).
307 */
308
309
310 /* #define REALLOC_ZERO_BYTES_FREES */
311
312
313 /*
314 WIN32 causes an emulation of sbrk to be compiled in
315 mmap-based options are not currently supported in WIN32.
316 */
317
318 /* #define WIN32 */
319 #ifdef WIN32
320 #define MORECORE wsbrk
321 #define HAVE_MMAP 0
322
323 #define LACKS_UNISTD_H
324 #define LACKS_SYS_PARAM_H
325
326 /*
327 Include 'windows.h' to get the necessary declarations for the
328 Microsoft Visual C++ data structures and routines used in the 'sbrk'
329 emulation.
330
331 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
332 Visual C++ header files are included.
333 */
334 #define WIN32_LEAN_AND_MEAN
335 #include <windows.h>
336 #endif
337
338
339 /*
340 HAVE_MEMCPY should be defined if you are not otherwise using
341 ANSI STD C, but still have memcpy and memset in your C library
342 and want to use them in calloc and realloc. Otherwise simple
343 macro versions are defined here.
344
345 USE_MEMCPY should be defined as 1 if you actually want to
346 have memset and memcpy called. People report that the macro
347 versions are often enough faster than libc versions on many
348 systems that it is better to use them.
349
350 */
351
352 #define HAVE_MEMCPY
353
354 #ifndef USE_MEMCPY
355 #ifdef HAVE_MEMCPY
356 #define USE_MEMCPY 1
357 #else
358 #define USE_MEMCPY 0
359 #endif
360 #endif
361
362 #if (__STD_C || defined(HAVE_MEMCPY))
363
364 #if __STD_C
365 /* U-Boot defines memset() and memcpy in /include/linux/string.h
366 void* memset(void*, int, size_t);
367 void* memcpy(void*, const void*, size_t);
368 */
369 #include <linux/string.h>
370 #else
371 #ifdef WIN32
372 /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
373 /* 'windows.h' */
374 #else
375 Void_t* memset();
376 Void_t* memcpy();
377 #endif
378 #endif
379 #endif
380
381 #if USE_MEMCPY
382
383 /* The following macros are only invoked with (2n+1)-multiples of
384 INTERNAL_SIZE_T units, with a positive integer n. This is exploited
385 for fast inline execution when n is small. */
386
387 #define MALLOC_ZERO(charp, nbytes) \
388 do { \
389 INTERNAL_SIZE_T mzsz = (nbytes); \
390 if(mzsz <= 9*sizeof(mzsz)) { \
391 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
392 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
393 *mz++ = 0; \
394 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
395 *mz++ = 0; \
396 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
397 *mz++ = 0; }}} \
398 *mz++ = 0; \
399 *mz++ = 0; \
400 *mz = 0; \
401 } else memset((charp), 0, mzsz); \
402 } while(0)
403
404 #define MALLOC_COPY(dest,src,nbytes) \
405 do { \
406 INTERNAL_SIZE_T mcsz = (nbytes); \
407 if(mcsz <= 9*sizeof(mcsz)) { \
408 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
409 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
410 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
411 *mcdst++ = *mcsrc++; \
412 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
413 *mcdst++ = *mcsrc++; \
414 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
415 *mcdst++ = *mcsrc++; }}} \
416 *mcdst++ = *mcsrc++; \
417 *mcdst++ = *mcsrc++; \
418 *mcdst = *mcsrc ; \
419 } else memcpy(dest, src, mcsz); \
420 } while(0)
421
422 #else /* !USE_MEMCPY */
423
424 /* Use Duff's device for good zeroing/copying performance. */
425
426 #define MALLOC_ZERO(charp, nbytes) \
427 do { \
428 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
429 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
430 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
431 switch (mctmp) { \
432 case 0: for(;;) { *mzp++ = 0; \
433 case 7: *mzp++ = 0; \
434 case 6: *mzp++ = 0; \
435 case 5: *mzp++ = 0; \
436 case 4: *mzp++ = 0; \
437 case 3: *mzp++ = 0; \
438 case 2: *mzp++ = 0; \
439 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
440 } \
441 } while(0)
442
443 #define MALLOC_COPY(dest,src,nbytes) \
444 do { \
445 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
446 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
447 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
448 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
449 switch (mctmp) { \
450 case 0: for(;;) { *mcdst++ = *mcsrc++; \
451 case 7: *mcdst++ = *mcsrc++; \
452 case 6: *mcdst++ = *mcsrc++; \
453 case 5: *mcdst++ = *mcsrc++; \
454 case 4: *mcdst++ = *mcsrc++; \
455 case 3: *mcdst++ = *mcsrc++; \
456 case 2: *mcdst++ = *mcsrc++; \
457 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
458 } \
459 } while(0)
460
461 #endif
462
463
464 /*
465 Define HAVE_MMAP to optionally make malloc() use mmap() to
466 allocate very large blocks. These will be returned to the
467 operating system immediately after a free().
468 */
469
470 /***
471 #ifndef HAVE_MMAP
472 #define HAVE_MMAP 1
473 #endif
474 ***/
475 #undef HAVE_MMAP /* Not available for U-Boot */
476
477 /*
478 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
479 large blocks. This is currently only possible on Linux with
480 kernel versions newer than 1.3.77.
481 */
482
483 /***
484 #ifndef HAVE_MREMAP
485 #ifdef INTERNAL_LINUX_C_LIB
486 #define HAVE_MREMAP 1
487 #else
488 #define HAVE_MREMAP 0
489 #endif
490 #endif
491 ***/
492 #undef HAVE_MREMAP /* Not available for U-Boot */
493
494 #ifdef HAVE_MMAP
495
496 #include <unistd.h>
497 #include <fcntl.h>
498 #include <sys/mman.h>
499
500 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
501 #define MAP_ANONYMOUS MAP_ANON
502 #endif
503
504 #endif /* HAVE_MMAP */
505
506 /*
507 Access to system page size. To the extent possible, this malloc
508 manages memory from the system in page-size units.
509
510 The following mechanics for getpagesize were adapted from
511 bsd/gnu getpagesize.h
512 */
513
514 #define LACKS_UNISTD_H /* Shortcut for U-Boot */
515 #define malloc_getpagesize 4096
516
517 #ifndef LACKS_UNISTD_H
518 # include <unistd.h>
519 #endif
520
521 #ifndef malloc_getpagesize
522 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
523 # ifndef _SC_PAGE_SIZE
524 # define _SC_PAGE_SIZE _SC_PAGESIZE
525 # endif
526 # endif
527 # ifdef _SC_PAGE_SIZE
528 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
529 # else
530 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
531 extern size_t getpagesize();
532 # define malloc_getpagesize getpagesize()
533 # else
534 # ifdef WIN32
535 # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
536 # else
537 # ifndef LACKS_SYS_PARAM_H
538 # include <sys/param.h>
539 # endif
540 # ifdef EXEC_PAGESIZE
541 # define malloc_getpagesize EXEC_PAGESIZE
542 # else
543 # ifdef NBPG
544 # ifndef CLSIZE
545 # define malloc_getpagesize NBPG
546 # else
547 # define malloc_getpagesize (NBPG * CLSIZE)
548 # endif
549 # else
550 # ifdef NBPC
551 # define malloc_getpagesize NBPC
552 # else
553 # ifdef PAGESIZE
554 # define malloc_getpagesize PAGESIZE
555 # else
556 # define malloc_getpagesize (4096) /* just guess */
557 # endif
558 # endif
559 # endif
560 # endif
561 # endif
562 # endif
563 # endif
564 #endif
565
566
567 /*
568
569 This version of malloc supports the standard SVID/XPG mallinfo
570 routine that returns a struct containing the same kind of
571 information you can get from malloc_stats. It should work on
572 any SVID/XPG compliant system that has a /usr/include/malloc.h
573 defining struct mallinfo. (If you'd like to install such a thing
574 yourself, cut out the preliminary declarations as described above
575 and below and save them in a malloc.h file. But there's no
576 compelling reason to bother to do this.)
577
578 The main declaration needed is the mallinfo struct that is returned
579 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
580 bunch of fields, most of which are not even meaningful in this
581 version of malloc. Some of these fields are are instead filled by
582 mallinfo() with other numbers that might possibly be of interest.
583
584 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
585 /usr/include/malloc.h file that includes a declaration of struct
586 mallinfo. If so, it is included; else an SVID2/XPG2 compliant
587 version is declared below. These must be precisely the same for
588 mallinfo() to work.
589
590 */
591
592 /* #define HAVE_USR_INCLUDE_MALLOC_H */
593
594 #ifdef HAVE_USR_INCLUDE_MALLOC_H
595 #include "/usr/include/malloc.h"
596 #else
597
598 /* SVID2/XPG mallinfo structure */
599
600 struct mallinfo {
601 int arena; /* total space allocated from system */
602 int ordblks; /* number of non-inuse chunks */
603 int smblks; /* unused -- always zero */
604 int hblks; /* number of mmapped regions */
605 int hblkhd; /* total space in mmapped regions */
606 int usmblks; /* unused -- always zero */
607 int fsmblks; /* unused -- always zero */
608 int uordblks; /* total allocated space */
609 int fordblks; /* total non-inuse space */
610 int keepcost; /* top-most, releasable (via malloc_trim) space */
611 };
612
613 /* SVID2/XPG mallopt options */
614
615 #define M_MXFAST 1 /* UNUSED in this malloc */
616 #define M_NLBLKS 2 /* UNUSED in this malloc */
617 #define M_GRAIN 3 /* UNUSED in this malloc */
618 #define M_KEEP 4 /* UNUSED in this malloc */
619
620 #endif
621
622 /* mallopt options that actually do something */
623
624 #define M_TRIM_THRESHOLD -1
625 #define M_TOP_PAD -2
626 #define M_MMAP_THRESHOLD -3
627 #define M_MMAP_MAX -4
628
629
630 #ifndef DEFAULT_TRIM_THRESHOLD
631 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
632 #endif
633
634 /*
635 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
636 to keep before releasing via malloc_trim in free().
637
638 Automatic trimming is mainly useful in long-lived programs.
639 Because trimming via sbrk can be slow on some systems, and can
640 sometimes be wasteful (in cases where programs immediately
641 afterward allocate more large chunks) the value should be high
642 enough so that your overall system performance would improve by
643 releasing.
644
645 The trim threshold and the mmap control parameters (see below)
646 can be traded off with one another. Trimming and mmapping are
647 two different ways of releasing unused memory back to the
648 system. Between these two, it is often possible to keep
649 system-level demands of a long-lived program down to a bare
650 minimum. For example, in one test suite of sessions measuring
651 the XF86 X server on Linux, using a trim threshold of 128K and a
652 mmap threshold of 192K led to near-minimal long term resource
653 consumption.
654
655 If you are using this malloc in a long-lived program, it should
656 pay to experiment with these values. As a rough guide, you
657 might set to a value close to the average size of a process
658 (program) running on your system. Releasing this much memory
659 would allow such a process to run in memory. Generally, it's
660 worth it to tune for trimming rather tham memory mapping when a
661 program undergoes phases where several large chunks are
662 allocated and released in ways that can reuse each other's
663 storage, perhaps mixed with phases where there are no such
664 chunks at all. And in well-behaved long-lived programs,
665 controlling release of large blocks via trimming versus mapping
666 is usually faster.
667
668 However, in most programs, these parameters serve mainly as
669 protection against the system-level effects of carrying around
670 massive amounts of unneeded memory. Since frequent calls to
671 sbrk, mmap, and munmap otherwise degrade performance, the default
672 parameters are set to relatively high values that serve only as
673 safeguards.
674
675 The default trim value is high enough to cause trimming only in
676 fairly extreme (by current memory consumption standards) cases.
677 It must be greater than page size to have any useful effect. To
678 disable trimming completely, you can set to (unsigned long)(-1);
679
680
681 */
682
683
684 #ifndef DEFAULT_TOP_PAD
685 #define DEFAULT_TOP_PAD (0)
686 #endif
687
688 /*
689 M_TOP_PAD is the amount of extra `padding' space to allocate or
690 retain whenever sbrk is called. It is used in two ways internally:
691
692 * When sbrk is called to extend the top of the arena to satisfy
693 a new malloc request, this much padding is added to the sbrk
694 request.
695
696 * When malloc_trim is called automatically from free(),
697 it is used as the `pad' argument.
698
699 In both cases, the actual amount of padding is rounded
700 so that the end of the arena is always a system page boundary.
701
702 The main reason for using padding is to avoid calling sbrk so
703 often. Having even a small pad greatly reduces the likelihood
704 that nearly every malloc request during program start-up (or
705 after trimming) will invoke sbrk, which needlessly wastes
706 time.
707
708 Automatic rounding-up to page-size units is normally sufficient
709 to avoid measurable overhead, so the default is 0. However, in
710 systems where sbrk is relatively slow, it can pay to increase
711 this value, at the expense of carrying around more memory than
712 the program needs.
713
714 */
715
716
717 #ifndef DEFAULT_MMAP_THRESHOLD
718 #define DEFAULT_MMAP_THRESHOLD (128 * 1024)
719 #endif
720
721 /*
722
723 M_MMAP_THRESHOLD is the request size threshold for using mmap()
724 to service a request. Requests of at least this size that cannot
725 be allocated using already-existing space will be serviced via mmap.
726 (If enough normal freed space already exists it is used instead.)
727
728 Using mmap segregates relatively large chunks of memory so that
729 they can be individually obtained and released from the host
730 system. A request serviced through mmap is never reused by any
731 other request (at least not directly; the system may just so
732 happen to remap successive requests to the same locations).
733
734 Segregating space in this way has the benefit that mmapped space
735 can ALWAYS be individually released back to the system, which
736 helps keep the system level memory demands of a long-lived
737 program low. Mapped memory can never become `locked' between
738 other chunks, as can happen with normally allocated chunks, which
739 menas that even trimming via malloc_trim would not release them.
740
741 However, it has the disadvantages that:
742
743 1. The space cannot be reclaimed, consolidated, and then
744 used to service later requests, as happens with normal chunks.
745 2. It can lead to more wastage because of mmap page alignment
746 requirements
747 3. It causes malloc performance to be more dependent on host
748 system memory management support routines which may vary in
749 implementation quality and may impose arbitrary
750 limitations. Generally, servicing a request via normal
751 malloc steps is faster than going through a system's mmap.
752
753 All together, these considerations should lead you to use mmap
754 only for relatively large requests.
755
756
757 */
758
759
760 #ifndef DEFAULT_MMAP_MAX
761 #ifdef HAVE_MMAP
762 #define DEFAULT_MMAP_MAX (64)
763 #else
764 #define DEFAULT_MMAP_MAX (0)
765 #endif
766 #endif
767
768 /*
769 M_MMAP_MAX is the maximum number of requests to simultaneously
770 service using mmap. This parameter exists because:
771
772 1. Some systems have a limited number of internal tables for
773 use by mmap.
774 2. In most systems, overreliance on mmap can degrade overall
775 performance.
776 3. If a program allocates many large regions, it is probably
777 better off using normal sbrk-based allocation routines that
778 can reclaim and reallocate normal heap memory. Using a
779 small value allows transition into this mode after the
780 first few allocations.
781
782 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
783 the default value is 0, and attempts to set it to non-zero values
784 in mallopt will fail.
785 */
786
787
788 /*
789 USE_DL_PREFIX will prefix all public routines with the string 'dl'.
790 Useful to quickly avoid procedure declaration conflicts and linker
791 symbol conflicts with existing memory allocation routines.
792
793 */
794
795 /*
796 * Rename the U-Boot alloc functions so that sandbox can still use the system
797 * ones
798 */
799 #ifdef CONFIG_SANDBOX
800 #define USE_DL_PREFIX
801 #endif
802
803 /*
804
805 Special defines for linux libc
806
807 Except when compiled using these special defines for Linux libc
808 using weak aliases, this malloc is NOT designed to work in
809 multithreaded applications. No semaphores or other concurrency
810 control are provided to ensure that multiple malloc or free calls
811 don't run at the same time, which could be disasterous. A single
812 semaphore could be used across malloc, realloc, and free (which is
813 essentially the effect of the linux weak alias approach). It would
814 be hard to obtain finer granularity.
815
816 */
817
818
819 #ifdef INTERNAL_LINUX_C_LIB
820
821 #if __STD_C
822
823 Void_t * __default_morecore_init (ptrdiff_t);
824 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
825
826 #else
827
828 Void_t * __default_morecore_init ();
829 Void_t *(*__morecore)() = __default_morecore_init;
830
831 #endif
832
833 #define MORECORE (*__morecore)
834 #define MORECORE_FAILURE 0
835 #define MORECORE_CLEARS 1
836
837 #else /* INTERNAL_LINUX_C_LIB */
838
839 #if __STD_C
840 extern Void_t* sbrk(ptrdiff_t);
841 #else
842 extern Void_t* sbrk();
843 #endif
844
845 #ifndef MORECORE
846 #define MORECORE sbrk
847 #endif
848
849 #ifndef MORECORE_FAILURE
850 #define MORECORE_FAILURE -1
851 #endif
852
853 #ifndef MORECORE_CLEARS
854 #define MORECORE_CLEARS 1
855 #endif
856
857 #endif /* INTERNAL_LINUX_C_LIB */
858
859 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
860
861 #define cALLOc __libc_calloc
862 #define fREe __libc_free
863 #define mALLOc __libc_malloc
864 #define mEMALIGn __libc_memalign
865 #define rEALLOc __libc_realloc
866 #define vALLOc __libc_valloc
867 #define pvALLOc __libc_pvalloc
868 #define mALLINFo __libc_mallinfo
869 #define mALLOPt __libc_mallopt
870
871 #pragma weak calloc = __libc_calloc
872 #pragma weak free = __libc_free
873 #pragma weak cfree = __libc_free
874 #pragma weak malloc = __libc_malloc
875 #pragma weak memalign = __libc_memalign
876 #pragma weak realloc = __libc_realloc
877 #pragma weak valloc = __libc_valloc
878 #pragma weak pvalloc = __libc_pvalloc
879 #pragma weak mallinfo = __libc_mallinfo
880 #pragma weak mallopt = __libc_mallopt
881
882 #else
883
884 void malloc_simple_info(void);
885
886 #if CONFIG_IS_ENABLED(SYS_MALLOC_SIMPLE)
887 #define malloc malloc_simple
888 #define realloc realloc_simple
889 #define memalign memalign_simple
free(void * ptr)890 static inline void free(void *ptr) {}
891 void *calloc(size_t nmemb, size_t size);
892 void *realloc_simple(void *ptr, size_t size);
893 #else
894
895 # ifdef USE_DL_PREFIX
896 # define cALLOc dlcalloc
897 # define fREe dlfree
898 # define mALLOc dlmalloc
899 # define mEMALIGn dlmemalign
900 # define rEALLOc dlrealloc
901 # define vALLOc dlvalloc
902 # define pvALLOc dlpvalloc
903 # define mALLINFo dlmallinfo
904 # define mALLOPt dlmallopt
905
906 /* Ensure that U-Boot actually uses these too */
907 #define calloc dlcalloc
908 #define free(ptr) dlfree(ptr)
909 #define malloc(x) dlmalloc(x)
910 #define memalign dlmemalign
911 #define realloc dlrealloc
912 #define valloc dlvalloc
913 #define pvalloc dlpvalloc
914 #define mallinfo() dlmallinfo()
915 #define mallopt dlmallopt
916 #define malloc_trim dlmalloc_trim
917 #define malloc_usable_size dlmalloc_usable_size
918 #define malloc_stats dlmalloc_stats
919
920 # else /* USE_DL_PREFIX */
921 # define cALLOc calloc
922 # define fREe free
923 # define mALLOc malloc
924 # define mEMALIGn memalign
925 # define rEALLOc realloc
926 # define vALLOc valloc
927 # define pvALLOc pvalloc
928 # define mALLINFo mallinfo
929 # define mALLOPt mallopt
930 # endif /* USE_DL_PREFIX */
931
932 #endif
933
934 /* Set up pre-relocation malloc() ready for use */
935 int initf_malloc(void);
936
937 /* Public routines */
938
939 /* Simple versions which can be used when space is tight */
940 void *malloc_simple(size_t size);
941 void *memalign_simple(size_t alignment, size_t bytes);
942
943 #pragma GCC visibility push(hidden)
944 # if __STD_C
945
946 Void_t* mALLOc(size_t);
947 void fREe(Void_t*);
948 Void_t* rEALLOc(Void_t*, size_t);
949 Void_t* mEMALIGn(size_t, size_t);
950 Void_t* vALLOc(size_t);
951 Void_t* pvALLOc(size_t);
952 Void_t* cALLOc(size_t, size_t);
953 void cfree(Void_t*);
954 int malloc_trim(size_t);
955 size_t malloc_usable_size(Void_t*);
956 void malloc_stats(void);
957 int mALLOPt(int, int);
958 struct mallinfo mALLINFo(void);
959 # else
960 Void_t* mALLOc();
961 void fREe();
962 Void_t* rEALLOc();
963 Void_t* mEMALIGn();
964 Void_t* vALLOc();
965 Void_t* pvALLOc();
966 Void_t* cALLOc();
967 void cfree();
968 int malloc_trim();
969 size_t malloc_usable_size();
970 void malloc_stats();
971 int mALLOPt();
972 struct mallinfo mALLINFo();
973 # endif
974 #endif
975 #pragma GCC visibility pop
976
977 /*
978 * Begin and End of memory area for malloc(), and current "brk"
979 */
980 extern ulong mem_malloc_start;
981 extern ulong mem_malloc_end;
982 extern ulong mem_malloc_brk;
983
984 void mem_malloc_init(ulong start, ulong size);
985
986 #ifdef __cplusplus
987 }; /* end of extern "C" */
988 #endif
989
990 #endif /* __MALLOC_H__ */
991