1 /* Malloc implementation for multiple threads without lock contention.
2 Copyright (C) 1996-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Wolfram Gloger <wg@malloc.de>
5 and Doug Lea <dl@cs.oswego.edu>, 2001.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; see the file COPYING.LIB. If
19 not, see <http://www.gnu.org/licenses/>. */
22 This is a version (aka ptmalloc2) of malloc/free/realloc written by
23 Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.
25 There have been substantial changes made after the integration into
26 glibc in all parts of the code. Do not look for much commonality
27 with the ptmalloc2 version.
29 * Version ptmalloc2-20011215
31 VERSION 2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
35 In order to compile this implementation, a Makefile is provided with
36 the ptmalloc2 distribution, which has pre-defined targets for some
37 popular systems (e.g. "make posix" for Posix threads). All that is
38 typically required with regard to compiler flags is the selection of
39 the thread package via defining one out of USE_PTHREADS, USE_THR or
40 USE_SPROC. Check the thread-m.h file for what effects this has.
41 Many/most systems will additionally require USE_TSD_DATA_HACK to be
42 defined, so this is the default for "make posix".
44 * Why use this malloc?
46 This is not the fastest, most space-conserving, most portable, or
47 most tunable malloc ever written. However it is among the fastest
48 while also being among the most space-conserving, portable and tunable.
49 Consistent balance across these factors results in a good general-purpose
50 allocator for malloc-intensive programs.
52 The main properties of the algorithms are:
53 * For large (>= 512 bytes) requests, it is a pure best-fit allocator,
54 with ties normally decided via FIFO (i.e. least recently used).
55 * For small (<= 64 bytes by default) requests, it is a caching
56 allocator, that maintains pools of quickly recycled chunks.
57 * In between, and for combinations of large and small requests, it does
58 the best it can trying to meet both goals at once.
59 * For very large requests (>= 128KB by default), it relies on system
60 memory mapping facilities, if supported.
62 For a longer but slightly out of date high-level description, see
63 http://gee.cs.oswego.edu/dl/html/malloc.html
65 You may already by default be using a C library containing a malloc
66 that is based on some version of this malloc (for example in
67 linux). You might still want to use the one in this file in order to
68 customize settings or to avoid overheads associated with library
71 * Contents, described in more detail in "description of public routines" below.
73 Standard (ANSI/SVID/...) functions:
75 calloc(size_t n_elements, size_t element_size);
77 realloc(void* p, size_t n);
78 memalign(size_t alignment, size_t n);
81 mallopt(int parameter_number, int parameter_value)
84 independent_calloc(size_t n_elements, size_t size, void* chunks[]);
85 independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]);
87 malloc_trim(size_t pad);
88 malloc_usable_size(void* p);
93 Supported pointer representation: 4 or 8 bytes
94 Supported size_t representation: 4 or 8 bytes
95 Note that size_t is allowed to be 4 bytes even if pointers are 8.
96 You can adjust this by defining INTERNAL_SIZE_T
98 Alignment: 2 * sizeof(size_t) (default)
99 (i.e., 8 byte alignment with 4byte size_t). This suffices for
100 nearly all current machines and C compilers. However, you can
101 define MALLOC_ALIGNMENT to be wider than this if necessary.
103 Minimum overhead per allocated chunk: 4 or 8 bytes
104 Each malloced chunk has a hidden word of overhead holding size
105 and status information.
107 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
108 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
110 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
111 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
112 needed; 4 (8) for a trailing size field and 8 (16) bytes for
113 free list pointers. Thus, the minimum allocatable size is
116 Even a request for zero bytes (i.e., malloc(0)) returns a
117 pointer to something of the minimum allocatable size.
119 The maximum overhead wastage (i.e., number of extra bytes
120 allocated than were requested in malloc) is less than or equal
121 to the minimum size, except for requests >= mmap_threshold that
122 are serviced via mmap(), where the worst case wastage is 2 *
123 sizeof(size_t) bytes plus the remainder from a system page (the
124 minimal mmap unit); typically 4096 or 8192 bytes.
126 Maximum allocated size: 4-byte size_t: 2^32 minus about two pages
127 8-byte size_t: 2^64 minus about two pages
129 It is assumed that (possibly signed) size_t values suffice to
130 represent chunk sizes. `Possibly signed' is due to the fact
131 that `size_t' may be defined on a system as either a signed or
132 an unsigned type. The ISO C standard says that it must be
133 unsigned, but a few systems are known not to adhere to this.
134 Additionally, even when size_t is unsigned, sbrk (which is by
135 default used to obtain memory from system) accepts signed
136 arguments, and may not be able to handle size_t-wide arguments
137 with negative sign bit. Generally, values that would
138 appear as negative after accounting for overhead and alignment
139 are supported only via mmap(), which does not have this
142 Requests for sizes outside the allowed range will perform an optional
143 failure action and then return null. (Requests may also
144 also fail because a system is out of memory.)
146 Thread-safety: thread-safe
148 Compliance: I believe it is compliant with the 1997 Single Unix Specification
149 Also SVID/XPG, ANSI C, and probably others as well.
151 * Synopsis of compile-time options:
153 People have reported using previous versions of this malloc on all
154 versions of Unix, sometimes by tweaking some of the defines
155 below. It has been tested most extensively on Solaris and Linux.
156 People also report using it in stand-alone embedded systems.
158 The implementation is in straight, hand-tuned ANSI C. It is not
159 at all modular. (Sorry!) It uses a lot of macros. To be at all
160 usable, this code should be compiled using an optimizing compiler
161 (for example gcc -O3) that can simplify expressions and control
162 paths. (FAQ: some macros import variables as arguments rather than
163 declare locals because people reported that some debuggers
164 otherwise get confused.)
168 Compilation Environment options:
172 Changing default word sizes:
174 INTERNAL_SIZE_T size_t
176 Configuration and functionality options:
178 USE_PUBLIC_MALLOC_WRAPPERS NOT defined
179 USE_MALLOC_LOCK NOT defined
180 MALLOC_DEBUG NOT defined
181 REALLOC_ZERO_BYTES_FREES 1
184 Options for customizing MORECORE:
188 MORECORE_CONTIGUOUS 1
189 MORECORE_CANNOT_TRIM NOT defined
191 MMAP_AS_MORECORE_SIZE (1024 * 1024)
193 Tuning options that are also dynamically changeable via mallopt:
195 DEFAULT_MXFAST 64 (for 32bit), 128 (for 64bit)
196 DEFAULT_TRIM_THRESHOLD 128 * 1024
198 DEFAULT_MMAP_THRESHOLD 128 * 1024
199 DEFAULT_MMAP_MAX 65536
201 There are several other #defined constants and macros that you
202 probably don't want to touch unless you are extending or adapting malloc. */
205 void* is the pointer type that malloc should say it returns
212 #include <stddef.h> /* for size_t */
213 #include <stdlib.h> /* for getenv(), abort() */
214 #include <unistd.h> /* for __libc_enable_secure */
218 #include <bits/wordsize.h>
219 #include <sys/sysinfo.h>
221 #include <ldsodefs.h>
224 #include <stdio.h> /* needed for malloc_stats */
227 #include <shlib-compat.h>
232 /* For va_arg, va_start, va_end. */
235 /* For MIN, MAX, powerof2. */
236 #include <sys/param.h>
238 /* For ALIGN_UP et. al. */
239 #include <libc-pointer-arith.h>
241 /* For DIAG_PUSH/POP_NEEDS_COMMENT et al. */
242 #include <libc-diag.h>
244 #include <malloc/malloc-internal.h>
249 Because freed chunks may be overwritten with bookkeeping fields, this
250 malloc will often die when freed memory is overwritten by user
251 programs. This can be very effective (albeit in an annoying way)
252 in helping track down dangling pointers.
254 If you compile with -DMALLOC_DEBUG, a number of assertion checks are
255 enabled that will catch more memory errors. You probably won't be
256 able to make much sense of the actual assertion errors, but they
257 should help you locate incorrectly overwritten memory. The checking
258 is fairly extensive, and will slow down execution
259 noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
260 will attempt to check every non-mmapped allocated and free chunk in
261 the course of computing the summmaries. (By nature, mmapped regions
262 cannot be checked very much automatically.)
264 Setting MALLOC_DEBUG may also be helpful if you are trying to modify
265 this code. The assertions in the check routines spell out in more
266 detail the assumptions and invariants underlying the algorithms.
268 Setting MALLOC_DEBUG does NOT provide an automated mechanism for
269 checking that all accesses to malloced memory stay within their
270 bounds. However, there are several add-ons and adaptations of this
271 or other mallocs available that do this.
275 #define MALLOC_DEBUG 0
279 # define assert(expr) ((void) 0)
281 # define assert(expr) \
284 : __malloc_assert (#expr, __FILE__, __LINE__, __func__))
286 extern const char *__progname
;
289 __malloc_assert (const char *assertion
, const char *file
, unsigned int line
,
290 const char *function
)
292 (void) __fxprintf (NULL
, "%s%s%s:%u: %s%sAssertion `%s' failed.\n",
293 __progname
, __progname
[0] ? ": " : "",
295 function
? function
: "", function
? ": " : "",
303 /* We want 64 entries. This is an arbitrary limit, which tunables can reduce. */
304 # define TCACHE_MAX_BINS 64
305 # define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1)
307 /* Only used to pre-fill the tunables. */
308 # define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
310 /* When "x" is from chunksize(). */
311 # define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT)
312 /* When "x" is a user-provided size. */
313 # define usize2tidx(x) csize2tidx (request2size (x))
315 /* With rounding and alignment, the bins are...
316 idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit)
317 idx 1 bytes 25..40 or 13..20
318 idx 2 bytes 41..56 or 21..28
321 /* This is another arbitrary limit, which tunables can change. Each
322 tcache bin will hold at most this number of chunks. */
323 # define TCACHE_FILL_COUNT 7
328 REALLOC_ZERO_BYTES_FREES should be set if a call to
329 realloc with zero bytes should be the same as a call to free.
330 This is required by the C standard. Otherwise, since this malloc
331 returns a unique pointer for malloc(0), so does realloc(p, 0).
334 #ifndef REALLOC_ZERO_BYTES_FREES
335 #define REALLOC_ZERO_BYTES_FREES 1
339 TRIM_FASTBINS controls whether free() of a very small chunk can
340 immediately lead to trimming. Setting to true (1) can reduce memory
341 footprint, but will almost always slow down programs that use a lot
344 Define this only if you are willing to give up some speed to more
345 aggressively reduce system-level memory footprint when releasing
346 memory in programs that use many small chunks. You can get
347 essentially the same effect by setting MXFAST to 0, but this can
348 lead to even greater slowdowns in programs using many small chunks.
349 TRIM_FASTBINS is an in-between compile-time option, that disables
350 only those chunks bordering topmost memory from being placed in
354 #ifndef TRIM_FASTBINS
355 #define TRIM_FASTBINS 0
359 /* Definition for getting more memory from the OS. */
360 #define MORECORE (*__morecore)
361 #define MORECORE_FAILURE 0
362 void * __default_morecore (ptrdiff_t);
363 void *(*__morecore
)(ptrdiff_t) = __default_morecore
;
369 MORECORE-related declarations. By default, rely on sbrk
374 MORECORE is the name of the routine to call to obtain more memory
375 from the system. See below for general guidance on writing
376 alternative MORECORE functions, as well as a version for WIN32 and a
377 sample version for pre-OSX macos.
381 #define MORECORE sbrk
385 MORECORE_FAILURE is the value returned upon failure of MORECORE
386 as well as mmap. Since it cannot be an otherwise valid memory address,
387 and must reflect values of standard sys calls, you probably ought not
391 #ifndef MORECORE_FAILURE
392 #define MORECORE_FAILURE (-1)
396 If MORECORE_CONTIGUOUS is true, take advantage of fact that
397 consecutive calls to MORECORE with positive arguments always return
398 contiguous increasing addresses. This is true of unix sbrk. Even
399 if not defined, when regions happen to be contiguous, malloc will
400 permit allocations spanning regions obtained from different
401 calls. But defining this when applicable enables some stronger
402 consistency checks and space efficiencies.
405 #ifndef MORECORE_CONTIGUOUS
406 #define MORECORE_CONTIGUOUS 1
410 Define MORECORE_CANNOT_TRIM if your version of MORECORE
411 cannot release space back to the system when given negative
412 arguments. This is generally necessary only if you are using
413 a hand-crafted MORECORE function that cannot handle negative arguments.
416 /* #define MORECORE_CANNOT_TRIM */
418 /* MORECORE_CLEARS (default 1)
419 The degree to which the routine mapped to MORECORE zeroes out
420 memory: never (0), only for newly allocated space (1) or always
421 (2). The distinction between (1) and (2) is necessary because on
422 some systems, if the application first decrements and then
423 increments the break value, the contents of the reallocated space
427 #ifndef MORECORE_CLEARS
428 # define MORECORE_CLEARS 1
433 MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
434 sbrk fails, and mmap is used as a backup. The value must be a
435 multiple of page size. This backup strategy generally applies only
436 when systems have "holes" in address space, so sbrk cannot perform
437 contiguous expansion, but there is still space available on system.
438 On systems for which this is known to be useful (i.e. most linux
439 kernels), this occurs only when programs allocate huge amounts of
440 memory. Between this, and the fact that mmap regions tend to be
441 limited, the size should be large, to avoid too many mmap calls and
442 thus avoid running out of kernel resources. */
444 #ifndef MMAP_AS_MORECORE_SIZE
445 #define MMAP_AS_MORECORE_SIZE (1024 * 1024)
449 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
454 #define HAVE_MREMAP 0
457 /* We may need to support __malloc_initialize_hook for backwards
460 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
461 # define HAVE_MALLOC_INIT_HOOK 1
463 # define HAVE_MALLOC_INIT_HOOK 0
468 This version of malloc supports the standard SVID/XPG mallinfo
469 routine that returns a struct containing usage properties and
470 statistics. It should work on any SVID/XPG compliant system that has
471 a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
472 install such a thing yourself, cut out the preliminary declarations
473 as described above and below and save them in a malloc.h file. But
474 there's no compelling reason to bother to do this.)
476 The main declaration needed is the mallinfo struct that is returned
477 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
478 bunch of fields that are not even meaningful in this version of
479 malloc. These fields are are instead filled by mallinfo() with
480 other numbers that might be of interest.
484 /* ---------- description of public routines ------------ */
488 Returns a pointer to a newly allocated chunk of at least n bytes, or null
489 if no space is available. Additionally, on failure, errno is
490 set to ENOMEM on ANSI C systems.
492 If n is zero, malloc returns a minumum-sized chunk. (The minimum
493 size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
494 systems.) On most systems, size_t is an unsigned type, so calls
495 with negative arguments are interpreted as requests for huge amounts
496 of space, which will often fail. The maximum supported value of n
497 differs across systems, but is in all cases less than the maximum
498 representable value of a size_t.
500 void* __libc_malloc(size_t);
501 libc_hidden_proto (__libc_malloc
)
505 Releases the chunk of memory pointed to by p, that had been previously
506 allocated using malloc or a related routine such as realloc.
507 It has no effect if p is null. It can have arbitrary (i.e., bad!)
508 effects if p has already been freed.
510 Unless disabled (using mallopt), freeing very large spaces will
511 when possible, automatically trigger operations that give
512 back unused memory to the system, thus reducing program footprint.
514 void __libc_free(void*);
515 libc_hidden_proto (__libc_free
)
518 calloc(size_t n_elements, size_t element_size);
519 Returns a pointer to n_elements * element_size bytes, with all locations
522 void* __libc_calloc(size_t, size_t);
525 realloc(void* p, size_t n)
526 Returns a pointer to a chunk of size n that contains the same data
527 as does chunk p up to the minimum of (n, p's size) bytes, or null
528 if no space is available.
530 The returned pointer may or may not be the same as p. The algorithm
531 prefers extending p when possible, otherwise it employs the
532 equivalent of a malloc-copy-free sequence.
534 If p is null, realloc is equivalent to malloc.
536 If space is not available, realloc returns null, errno is set (if on
537 ANSI) and p is NOT freed.
539 if n is for fewer bytes than already held by p, the newly unused
540 space is lopped off and freed if possible. Unless the #define
541 REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
542 zero (re)allocates a minimum-sized chunk.
544 Large chunks that were internally obtained via mmap will always be
545 grown using malloc-copy-free sequences unless the system supports
546 MREMAP (currently only linux).
548 The old unix realloc convention of allowing the last-free'd chunk
549 to be used as an argument to realloc is not supported.
551 void* __libc_realloc(void*, size_t);
552 libc_hidden_proto (__libc_realloc
)
555 memalign(size_t alignment, size_t n);
556 Returns a pointer to a newly allocated chunk of n bytes, aligned
557 in accord with the alignment argument.
559 The alignment argument should be a power of two. If the argument is
560 not a power of two, the nearest greater power is used.
561 8-byte alignment is guaranteed by normal malloc calls, so don't
562 bother calling memalign with an argument of 8 or less.
564 Overreliance on memalign is a sure way to fragment space.
566 void* __libc_memalign(size_t, size_t);
567 libc_hidden_proto (__libc_memalign
)
571 Equivalent to memalign(pagesize, n), where pagesize is the page
572 size of the system. If the pagesize is unknown, 4096 is used.
574 void* __libc_valloc(size_t);
579 mallopt(int parameter_number, int parameter_value)
580 Sets tunable parameters The format is to provide a
581 (parameter-number, parameter-value) pair. mallopt then sets the
582 corresponding parameter to the argument value if it can (i.e., so
583 long as the value is meaningful), and returns 1 if successful else
584 0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
585 normally defined in malloc.h. Only one of these (M_MXFAST) is used
586 in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
587 so setting them has no effect. But this malloc also supports four
588 other options in mallopt. See below for details. Briefly, supported
589 parameters are as follows (listed defaults are for "typical"
592 Symbol param # default allowed param values
593 M_MXFAST 1 64 0-80 (0 disables fastbins)
594 M_TRIM_THRESHOLD -1 128*1024 any (-1U disables trimming)
596 M_MMAP_THRESHOLD -3 128*1024 any (or 0 if no MMAP support)
597 M_MMAP_MAX -4 65536 any (0 disables use of mmap)
599 int __libc_mallopt(int, int);
600 libc_hidden_proto (__libc_mallopt
)
605 Returns (by copy) a struct containing various summary statistics:
607 arena: current total non-mmapped bytes allocated from system
608 ordblks: the number of free chunks
609 smblks: the number of fastbin blocks (i.e., small chunks that
610 have been freed but not use resused or consolidated)
611 hblks: current number of mmapped regions
612 hblkhd: total bytes held in mmapped regions
614 fsmblks: total bytes held in fastbin blocks
615 uordblks: current total allocated space (normal or mmapped)
616 fordblks: total free space
617 keepcost: the maximum number of bytes that could ideally be released
618 back to system via malloc_trim. ("ideally" means that
619 it ignores page restrictions etc.)
621 Because these fields are ints, but internal bookkeeping may
622 be kept as longs, the reported values may wrap around zero and
625 struct mallinfo
__libc_mallinfo(void);
630 Equivalent to valloc(minimum-page-that-holds(n)), that is,
631 round up n to nearest pagesize.
633 void* __libc_pvalloc(size_t);
636 malloc_trim(size_t pad);
638 If possible, gives memory back to the system (via negative
639 arguments to sbrk) if there is unused memory at the `high' end of
640 the malloc pool. You can call this after freeing large blocks of
641 memory to potentially reduce the system-level memory requirements
642 of a program. However, it cannot guarantee to reduce memory. Under
643 some allocation patterns, some large free blocks of memory will be
644 locked between two used chunks, so they cannot be given back to
647 The `pad' argument to malloc_trim represents the amount of free
648 trailing space to leave untrimmed. If this argument is zero,
649 only the minimum amount of memory to maintain internal data
650 structures will be left (one page or less). Non-zero arguments
651 can be supplied to maintain enough trailing space to service
652 future expected allocations without having to re-obtain memory
655 Malloc_trim returns 1 if it actually released any memory, else 0.
656 On systems that do not support "negative sbrks", it will always
659 int __malloc_trim(size_t);
662 malloc_usable_size(void* p);
664 Returns the number of bytes you can actually use in
665 an allocated chunk, which may be more than you requested (although
666 often not) due to alignment and minimum size constraints.
667 You can use this many bytes without worrying about
668 overwriting other allocated objects. This is not a particularly great
669 programming practice. malloc_usable_size can be more useful in
670 debugging and assertions, for example:
673 assert(malloc_usable_size(p) >= 256);
676 size_t __malloc_usable_size(void*);
680 Prints on stderr the amount of space obtained from the system (both
681 via sbrk and mmap), the maximum amount (which may be more than
682 current if malloc_trim and/or munmap got called), and the current
683 number of bytes allocated via malloc (or realloc, etc) but not yet
684 freed. Note that this is the number of bytes allocated, not the
685 number requested. It will be larger than the number requested
686 because of alignment and bookkeeping overhead. Because it includes
687 alignment wastage as being in use, this figure may be greater than
688 zero even when no user-level chunks are allocated.
690 The reported current and maximum system memory can be inaccurate if
691 a program makes other calls to system memory allocation functions
692 (normally sbrk) outside of malloc.
694 malloc_stats prints only the most commonly interesting statistics.
695 More information can be obtained by calling mallinfo.
698 void __malloc_stats(void);
701 malloc_get_state(void);
703 Returns the state of all malloc variables in an opaque data
706 void* __malloc_get_state(void);
709 malloc_set_state(void* state);
711 Restore the state of all malloc variables from data obtained with
714 int __malloc_set_state(void*);
717 posix_memalign(void **memptr, size_t alignment, size_t size);
719 POSIX wrapper like memalign(), checking for validity of size.
721 int __posix_memalign(void **, size_t, size_t);
723 /* mallopt tuning options */
726 M_MXFAST is the maximum request size used for "fastbins", special bins
727 that hold returned chunks without consolidating their spaces. This
728 enables future requests for chunks of the same size to be handled
729 very quickly, but can increase fragmentation, and thus increase the
730 overall memory footprint of a program.
732 This malloc manages fastbins very conservatively yet still
733 efficiently, so fragmentation is rarely a problem for values less
734 than or equal to the default. The maximum supported value of MXFAST
735 is 80. You wouldn't want it any higher than this anyway. Fastbins
736 are designed especially for use with many small structs, objects or
737 strings -- the default handles structs/objects/arrays with sizes up
738 to 8 4byte fields, or small strings representing words, tokens,
739 etc. Using fastbins for larger objects normally worsens
740 fragmentation without improving speed.
742 M_MXFAST is set in REQUEST size units. It is internally used in
743 chunksize units, which adds padding and alignment. You can reduce
744 M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
745 algorithm to be a closer approximation of fifo-best-fit in all cases,
746 not just for larger requests, but will generally cause it to be
751 /* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
756 #ifndef DEFAULT_MXFAST
757 #define DEFAULT_MXFAST (64 * SIZE_SZ / 4)
762 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
763 to keep before releasing via malloc_trim in free().
765 Automatic trimming is mainly useful in long-lived programs.
766 Because trimming via sbrk can be slow on some systems, and can
767 sometimes be wasteful (in cases where programs immediately
768 afterward allocate more large chunks) the value should be high
769 enough so that your overall system performance would improve by
770 releasing this much memory.
772 The trim threshold and the mmap control parameters (see below)
773 can be traded off with one another. Trimming and mmapping are
774 two different ways of releasing unused memory back to the
775 system. Between these two, it is often possible to keep
776 system-level demands of a long-lived program down to a bare
777 minimum. For example, in one test suite of sessions measuring
778 the XF86 X server on Linux, using a trim threshold of 128K and a
779 mmap threshold of 192K led to near-minimal long term resource
782 If you are using this malloc in a long-lived program, it should
783 pay to experiment with these values. As a rough guide, you
784 might set to a value close to the average size of a process
785 (program) running on your system. Releasing this much memory
786 would allow such a process to run in memory. Generally, it's
787 worth it to tune for trimming rather tham memory mapping when a
788 program undergoes phases where several large chunks are
789 allocated and released in ways that can reuse each other's
790 storage, perhaps mixed with phases where there are no such
791 chunks at all. And in well-behaved long-lived programs,
792 controlling release of large blocks via trimming versus mapping
795 However, in most programs, these parameters serve mainly as
796 protection against the system-level effects of carrying around
797 massive amounts of unneeded memory. Since frequent calls to
798 sbrk, mmap, and munmap otherwise degrade performance, the default
799 parameters are set to relatively high values that serve only as
802 The trim value It must be greater than page size to have any useful
803 effect. To disable trimming completely, you can set to
806 Trim settings interact with fastbin (MXFAST) settings: Unless
807 TRIM_FASTBINS is defined, automatic trimming never takes place upon
808 freeing a chunk with size less than or equal to MXFAST. Trimming is
809 instead delayed until subsequent freeing of larger chunks. However,
810 you can still force an attempted trim by calling malloc_trim.
812 Also, trimming is not generally possible in cases where
813 the main arena is obtained via mmap.
815 Note that the trick some people use of mallocing a huge space and
816 then freeing it at program startup, in an attempt to reserve system
817 memory, doesn't have the intended effect under automatic trimming,
818 since that memory will immediately be returned to the system.
821 #define M_TRIM_THRESHOLD -1
823 #ifndef DEFAULT_TRIM_THRESHOLD
824 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
828 M_TOP_PAD is the amount of extra `padding' space to allocate or
829 retain whenever sbrk is called. It is used in two ways internally:
831 * When sbrk is called to extend the top of the arena to satisfy
832 a new malloc request, this much padding is added to the sbrk
835 * When malloc_trim is called automatically from free(),
836 it is used as the `pad' argument.
838 In both cases, the actual amount of padding is rounded
839 so that the end of the arena is always a system page boundary.
841 The main reason for using padding is to avoid calling sbrk so
842 often. Having even a small pad greatly reduces the likelihood
843 that nearly every malloc request during program start-up (or
844 after trimming) will invoke sbrk, which needlessly wastes
847 Automatic rounding-up to page-size units is normally sufficient
848 to avoid measurable overhead, so the default is 0. However, in
849 systems where sbrk is relatively slow, it can pay to increase
850 this value, at the expense of carrying around more memory than
856 #ifndef DEFAULT_TOP_PAD
857 #define DEFAULT_TOP_PAD (0)
861 MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
862 adjusted MMAP_THRESHOLD.
865 #ifndef DEFAULT_MMAP_THRESHOLD_MIN
866 #define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
869 #ifndef DEFAULT_MMAP_THRESHOLD_MAX
870 /* For 32-bit platforms we cannot increase the maximum mmap
871 threshold much because it is also the minimum value for the
872 maximum heap size and its alignment. Going above 512k (i.e., 1M
873 for new heaps) wastes too much address space. */
874 # if __WORDSIZE == 32
875 # define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
877 # define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
882 M_MMAP_THRESHOLD is the request size threshold for using mmap()
883 to service a request. Requests of at least this size that cannot
884 be allocated using already-existing space will be serviced via mmap.
885 (If enough normal freed space already exists it is used instead.)
887 Using mmap segregates relatively large chunks of memory so that
888 they can be individually obtained and released from the host
889 system. A request serviced through mmap is never reused by any
890 other request (at least not directly; the system may just so
891 happen to remap successive requests to the same locations).
893 Segregating space in this way has the benefits that:
895 1. Mmapped space can ALWAYS be individually released back
896 to the system, which helps keep the system level memory
897 demands of a long-lived program low.
898 2. Mapped memory can never become `locked' between
899 other chunks, as can happen with normally allocated chunks, which
900 means that even trimming via malloc_trim would not release them.
901 3. On some systems with "holes" in address spaces, mmap can obtain
902 memory that sbrk cannot.
904 However, it has the disadvantages that:
906 1. The space cannot be reclaimed, consolidated, and then
907 used to service later requests, as happens with normal chunks.
908 2. It can lead to more wastage because of mmap page alignment
910 3. It causes malloc performance to be more dependent on host
911 system memory management support routines which may vary in
912 implementation quality and may impose arbitrary
913 limitations. Generally, servicing a request via normal
914 malloc steps is faster than going through a system's mmap.
916 The advantages of mmap nearly always outweigh disadvantages for
917 "large" chunks, but the value of "large" varies across systems. The
918 default is an empirically derived value that works well in most
923 The above was written in 2001. Since then the world has changed a lot.
924 Memory got bigger. Applications got bigger. The virtual address space
925 layout in 32 bit linux changed.
927 In the new situation, brk() and mmap space is shared and there are no
928 artificial limits on brk size imposed by the kernel. What is more,
929 applications have started using transient allocations larger than the
930 128Kb as was imagined in 2001.
932 The price for mmap is also high now; each time glibc mmaps from the
933 kernel, the kernel is forced to zero out the memory it gives to the
934 application. Zeroing memory is expensive and eats a lot of cache and
935 memory bandwidth. This has nothing to do with the efficiency of the
936 virtual memory system, by doing mmap the kernel just has no choice but
939 In 2001, the kernel had a maximum size for brk() which was about 800
940 megabytes on 32 bit x86, at that point brk() would hit the first
941 mmaped shared libaries and couldn't expand anymore. With current 2.6
942 kernels, the VA space layout is different and brk() and mmap
943 both can span the entire heap at will.
945 Rather than using a static threshold for the brk/mmap tradeoff,
946 we are now using a simple dynamic one. The goal is still to avoid
947 fragmentation. The old goals we kept are
948 1) try to get the long lived large allocations to use mmap()
949 2) really large allocations should always use mmap()
950 and we're adding now:
951 3) transient allocations should use brk() to avoid forcing the kernel
952 having to zero memory over and over again
954 The implementation works with a sliding threshold, which is by default
955 limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
956 out at 128Kb as per the 2001 default.
958 This allows us to satisfy requirement 1) under the assumption that long
959 lived allocations are made early in the process' lifespan, before it has
960 started doing dynamic allocations of the same size (which will
961 increase the threshold).
963 The upperbound on the threshold satisfies requirement 2)
965 The threshold goes up in value when the application frees memory that was
966 allocated with the mmap allocator. The idea is that once the application
967 starts freeing memory of a certain size, it's highly probable that this is
968 a size the application uses for transient allocations. This estimator
969 is there to satisfy the new third requirement.
973 #define M_MMAP_THRESHOLD -3
975 #ifndef DEFAULT_MMAP_THRESHOLD
976 #define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
980 M_MMAP_MAX is the maximum number of requests to simultaneously
981 service using mmap. This parameter exists because
982 some systems have a limited number of internal tables for
983 use by mmap, and using more than a few of them may degrade
986 The default is set to a value that serves only as a safeguard.
987 Setting to 0 disables use of mmap for servicing large requests.
990 #define M_MMAP_MAX -4
992 #ifndef DEFAULT_MMAP_MAX
993 #define DEFAULT_MMAP_MAX (65536)
998 #ifndef RETURN_ADDRESS
999 #define RETURN_ADDRESS(X_) (NULL)
1002 /* Forward declarations. */
1003 struct malloc_chunk
;
1004 typedef struct malloc_chunk
* mchunkptr
;
1006 /* Internal routines. */
1008 static void* _int_malloc(mstate
, size_t);
1009 static void _int_free(mstate
, mchunkptr
, int);
1010 static void* _int_realloc(mstate
, mchunkptr
, INTERNAL_SIZE_T
,
1012 static void* _int_memalign(mstate
, size_t, size_t);
1013 static void* _mid_memalign(size_t, size_t, void *);
1015 static void malloc_printerr(const char *str
) __attribute__ ((noreturn
));
1017 static void* mem2mem_check(void *p
, size_t sz
);
1018 static void top_check(void);
1019 static void munmap_chunk(mchunkptr p
);
1021 static mchunkptr
mremap_chunk(mchunkptr p
, size_t new_size
);
1024 static void* malloc_check(size_t sz
, const void *caller
);
1025 static void free_check(void* mem
, const void *caller
);
1026 static void* realloc_check(void* oldmem
, size_t bytes
,
1027 const void *caller
);
1028 static void* memalign_check(size_t alignment
, size_t bytes
,
1029 const void *caller
);
1031 /* ------------------ MMAP support ------------------ */
1035 #include <sys/mman.h>
1037 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
1038 # define MAP_ANONYMOUS MAP_ANON
1041 #ifndef MAP_NORESERVE
1042 # define MAP_NORESERVE 0
1045 #define MMAP(addr, size, prot, flags) \
1046 __mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0)
1050 ----------------------- Chunk representations -----------------------
1055 This struct declaration is misleading (but accurate and necessary).
1056 It declares a "view" into memory allowing access to necessary
1057 fields at known offsets from a given base. See explanation below.
1060 struct malloc_chunk
{
1062 INTERNAL_SIZE_T mchunk_prev_size
; /* Size of previous chunk (if free). */
1063 INTERNAL_SIZE_T mchunk_size
; /* Size in bytes, including overhead. */
1065 struct malloc_chunk
* fd
; /* double links -- used only if free. */
1066 struct malloc_chunk
* bk
;
1068 /* Only used for large blocks: pointer to next larger size. */
1069 struct malloc_chunk
* fd_nextsize
; /* double links -- used only if free. */
1070 struct malloc_chunk
* bk_nextsize
;
1075 malloc_chunk details:
1077 (The following includes lightly edited explanations by Colin Plumb.)
1079 Chunks of memory are maintained using a `boundary tag' method as
1080 described in e.g., Knuth or Standish. (See the paper by Paul
1081 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1082 survey of such techniques.) Sizes of free chunks are stored both
1083 in the front of each chunk and at the end. This makes
1084 consolidating fragmented chunks into bigger chunks very fast. The
1085 size fields also hold bits representing whether chunks are free or
1088 An allocated chunk looks like this:
1091 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1092 | Size of previous chunk, if unallocated (P clear) |
1093 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1094 | Size of chunk, in bytes |A|M|P|
1095 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1096 | User data starts here... .
1098 . (malloc_usable_size() bytes) .
1100 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1101 | (size of chunk, but used for application data) |
1102 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1103 | Size of next chunk, in bytes |A|0|1|
1104 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1106 Where "chunk" is the front of the chunk for the purpose of most of
1107 the malloc code, but "mem" is the pointer that is returned to the
1108 user. "Nextchunk" is the beginning of the next contiguous chunk.
1110 Chunks always begin on even word boundaries, so the mem portion
1111 (which is returned to the user) is also on an even word boundary, and
1112 thus at least double-word aligned.
1114 Free chunks are stored in circular doubly-linked lists, and look like this:
1116 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1117 | Size of previous chunk, if unallocated (P clear) |
1118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1119 `head:' | Size of chunk, in bytes |A|0|P|
1120 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1121 | Forward pointer to next chunk in list |
1122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1123 | Back pointer to previous chunk in list |
1124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1125 | Unused space (may be 0 bytes long) .
1128 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1129 `foot:' | Size of chunk, in bytes |
1130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1131 | Size of next chunk, in bytes |A|0|0|
1132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1134 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1135 chunk size (which is always a multiple of two words), is an in-use
1136 bit for the *previous* chunk. If that bit is *clear*, then the
1137 word before the current chunk size contains the previous chunk
1138 size, and can be used to find the front of the previous chunk.
1139 The very first chunk allocated always has this bit set,
1140 preventing access to non-existent (or non-owned) memory. If
1141 prev_inuse is set for any given chunk, then you CANNOT determine
1142 the size of the previous chunk, and might even get a memory
1143 addressing fault when trying to do so.
1145 The A (NON_MAIN_ARENA) bit is cleared for chunks on the initial,
1146 main arena, described by the main_arena variable. When additional
1147 threads are spawned, each thread receives its own arena (up to a
1148 configurable limit, after which arenas are reused for multiple
1149 threads), and the chunks in these arenas have the A bit set. To
1150 find the arena for a chunk on such a non-main arena, heap_for_ptr
1151 performs a bit mask operation and indirection through the ar_ptr
1152 member of the per-heap header heap_info (see arena.c).
1154 Note that the `foot' of the current chunk is actually represented
1155 as the prev_size of the NEXT chunk. This makes it easier to
1156 deal with alignments etc but can be very confusing when trying
1157 to extend or adapt this code.
1159 The three exceptions to all this are:
1161 1. The special chunk `top' doesn't bother using the
1162 trailing size field since there is no next contiguous chunk
1163 that would have to index off it. After initialization, `top'
1164 is forced to always exist. If it would become less than
1165 MINSIZE bytes long, it is replenished.
1167 2. Chunks allocated via mmap, which have the second-lowest-order
1168 bit M (IS_MMAPPED) set in their size fields. Because they are
1169 allocated one-by-one, each must contain its own trailing size
1170 field. If the M bit is set, the other bits are ignored
1171 (because mmapped chunks are neither in an arena, nor adjacent
1172 to a freed chunk). The M bit is also used for chunks which
1173 originally came from a dumped heap via malloc_set_state in
1176 3. Chunks in fastbins are treated as allocated chunks from the
1177 point of view of the chunk allocator. They are consolidated
1178 with their neighbors only in bulk, in malloc_consolidate.
1182 ---------- Size and alignment checks and conversions ----------
1185 /* conversion from malloc headers to user pointers, and back */
1187 #define chunk2mem(p) ((void*)((char*)(p) + 2*SIZE_SZ))
1188 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
1190 /* The smallest possible chunk */
1191 #define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
1193 /* The smallest size we can malloc is an aligned minimal chunk */
1196 (unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
1198 /* Check if m has acceptable alignment */
1200 #define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
1202 #define misaligned_chunk(p) \
1203 ((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \
1204 & MALLOC_ALIGN_MASK)
1208 Check if a request is so large that it would wrap around zero when
1209 padded and aligned. To simplify some other code, the bound is made
1210 low enough so that adding MINSIZE will also not wrap around zero.
1213 #define REQUEST_OUT_OF_RANGE(req) \
1214 ((unsigned long) (req) >= \
1215 (unsigned long) (INTERNAL_SIZE_T) (-2 * MINSIZE))
1217 /* pad request bytes into a usable size -- internal version */
1219 #define request2size(req) \
1220 (((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
1222 ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
1224 /* Same, except also perform argument check */
1226 #define checked_request2size(req, sz) \
1227 if (REQUEST_OUT_OF_RANGE (req)) { \
1228 __set_errno (ENOMEM); \
1231 (sz) = request2size (req);
1234 --------------- Physical chunk operations ---------------
1238 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1239 #define PREV_INUSE 0x1
1241 /* extract inuse bit of previous chunk */
1242 #define prev_inuse(p) ((p)->mchunk_size & PREV_INUSE)
1245 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1246 #define IS_MMAPPED 0x2
1248 /* check for mmap()'ed chunk */
1249 #define chunk_is_mmapped(p) ((p)->mchunk_size & IS_MMAPPED)
1252 /* size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
1253 from a non-main arena. This is only set immediately before handing
1254 the chunk to the user, if necessary. */
1255 #define NON_MAIN_ARENA 0x4
1257 /* Check for chunk from main arena. */
1258 #define chunk_main_arena(p) (((p)->mchunk_size & NON_MAIN_ARENA) == 0)
1260 /* Mark a chunk as not being on the main arena. */
1261 #define set_non_main_arena(p) ((p)->mchunk_size |= NON_MAIN_ARENA)
1265 Bits to mask off when extracting size
1267 Note: IS_MMAPPED is intentionally not masked off from size field in
1268 macros for which mmapped chunks should never be seen. This should
1269 cause helpful core dumps to occur if it is tried by accident by
1270 people extending or adapting this malloc.
1272 #define SIZE_BITS (PREV_INUSE | IS_MMAPPED | NON_MAIN_ARENA)
1274 /* Get size, ignoring use bits */
1275 #define chunksize(p) (chunksize_nomask (p) & ~(SIZE_BITS))
1277 /* Like chunksize, but do not mask SIZE_BITS. */
1278 #define chunksize_nomask(p) ((p)->mchunk_size)
1280 /* Ptr to next physical malloc_chunk. */
1281 #define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
1283 /* Size of the chunk below P. Only valid if prev_inuse (P). */
1284 #define prev_size(p) ((p)->mchunk_prev_size)
1286 /* Set the size of the chunk below P. Only valid if prev_inuse (P). */
1287 #define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
1289 /* Ptr to previous physical malloc_chunk. Only valid if prev_inuse (P). */
1290 #define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
1292 /* Treat space at ptr + offset as a chunk */
1293 #define chunk_at_offset(p, s) ((mchunkptr) (((char *) (p)) + (s)))
1295 /* extract p's inuse bit */
1297 ((((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size) & PREV_INUSE)
1299 /* set/clear chunk as being inuse without otherwise disturbing */
1300 #define set_inuse(p) \
1301 ((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size |= PREV_INUSE
1303 #define clear_inuse(p) \
1304 ((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size &= ~(PREV_INUSE)
1307 /* check/set/clear inuse bits in known places */
1308 #define inuse_bit_at_offset(p, s) \
1309 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size & PREV_INUSE)
1311 #define set_inuse_bit_at_offset(p, s) \
1312 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size |= PREV_INUSE)
1314 #define clear_inuse_bit_at_offset(p, s) \
1315 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size &= ~(PREV_INUSE))
1318 /* Set size at head, without disturbing its use bit */
1319 #define set_head_size(p, s) ((p)->mchunk_size = (((p)->mchunk_size & SIZE_BITS) | (s)))
1321 /* Set size/use field */
1322 #define set_head(p, s) ((p)->mchunk_size = (s))
1324 /* Set size at footer (only when chunk is not in use) */
1325 #define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s))
1328 #pragma GCC poison mchunk_size
1329 #pragma GCC poison mchunk_prev_size
1332 -------------------- Internal data structures --------------------
1334 All internal state is held in an instance of malloc_state defined
1335 below. There are no other static variables, except in two optional
1337 * If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
1338 * If mmap doesn't support MAP_ANONYMOUS, a dummy file descriptor
1341 Beware of lots of tricks that minimize the total bookkeeping space
1342 requirements. The result is a little over 1K bytes (for 4byte
1343 pointers and size_t.)
1349 An array of bin headers for free chunks. Each bin is doubly
1350 linked. The bins are approximately proportionally (log) spaced.
1351 There are a lot of these bins (128). This may look excessive, but
1352 works very well in practice. Most bins hold sizes that are
1353 unusual as malloc request sizes, but are more usual for fragments
1354 and consolidated sets of chunks, which is what these bins hold, so
1355 they can be found quickly. All procedures maintain the invariant
1356 that no consolidated chunk physically borders another one, so each
1357 chunk in a list is known to be preceeded and followed by either
1358 inuse chunks or the ends of memory.
1360 Chunks in bins are kept in size order, with ties going to the
1361 approximately least recently used chunk. Ordering isn't needed
1362 for the small bins, which all contain the same-sized chunks, but
1363 facilitates best-fit allocation for larger chunks. These lists
1364 are just sequential. Keeping them in order almost never requires
1365 enough traversal to warrant using fancier ordered data
1368 Chunks of the same size are linked with the most
1369 recently freed at the front, and allocations are taken from the
1370 back. This results in LRU (FIFO) allocation order, which tends
1371 to give each chunk an equal opportunity to be consolidated with
1372 adjacent freed chunks, resulting in larger free chunks and less
1375 To simplify use in double-linked lists, each bin header acts
1376 as a malloc_chunk. This avoids special-casing for headers.
1377 But to conserve space and improve locality, we allocate
1378 only the fd/bk pointers of bins, and then use repositioning tricks
1379 to treat these as the fields of a malloc_chunk*.
1382 typedef struct malloc_chunk
*mbinptr
;
1384 /* addressing -- note that bin_at(0) does not exist */
1385 #define bin_at(m, i) \
1386 (mbinptr) (((char *) &((m)->bins[((i) - 1) * 2])) \
1387 - offsetof (struct malloc_chunk, fd))
1389 /* analog of ++bin */
1390 #define next_bin(b) ((mbinptr) ((char *) (b) + (sizeof (mchunkptr) << 1)))
1392 /* Reminders about list directionality within bins */
1393 #define first(b) ((b)->fd)
1394 #define last(b) ((b)->bk)
1396 /* Take a chunk off a bin list */
1397 #define unlink(AV, P, BK, FD) { \
1398 if (__builtin_expect (chunksize(P) != prev_size (next_chunk(P)), 0)) \
1399 malloc_printerr ("corrupted size vs. prev_size"); \
1402 if (__builtin_expect (FD->bk != P || BK->fd != P, 0)) \
1403 malloc_printerr ("corrupted double-linked list"); \
1407 if (!in_smallbin_range (chunksize_nomask (P)) \
1408 && __builtin_expect (P->fd_nextsize != NULL, 0)) { \
1409 if (__builtin_expect (P->fd_nextsize->bk_nextsize != P, 0) \
1410 || __builtin_expect (P->bk_nextsize->fd_nextsize != P, 0)) \
1411 malloc_printerr ("corrupted double-linked list (not small)"); \
1412 if (FD->fd_nextsize == NULL) { \
1413 if (P->fd_nextsize == P) \
1414 FD->fd_nextsize = FD->bk_nextsize = FD; \
1416 FD->fd_nextsize = P->fd_nextsize; \
1417 FD->bk_nextsize = P->bk_nextsize; \
1418 P->fd_nextsize->bk_nextsize = FD; \
1419 P->bk_nextsize->fd_nextsize = FD; \
1422 P->fd_nextsize->bk_nextsize = P->bk_nextsize; \
1423 P->bk_nextsize->fd_nextsize = P->fd_nextsize; \
1432 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1433 8 bytes apart. Larger bins are approximately logarithmically spaced:
1439 4 bins of size 32768
1440 2 bins of size 262144
1441 1 bin of size what's left
1443 There is actually a little bit of slop in the numbers in bin_index
1444 for the sake of speed. This makes no difference elsewhere.
1446 The bins top out around 1MB because we expect to service large
1449 Bin 0 does not exist. Bin 1 is the unordered list; if that would be
1450 a valid chunk size the small bins are bumped up one.
1454 #define NSMALLBINS 64
1455 #define SMALLBIN_WIDTH MALLOC_ALIGNMENT
1456 #define SMALLBIN_CORRECTION (MALLOC_ALIGNMENT > 2 * SIZE_SZ)
1457 #define MIN_LARGE_SIZE ((NSMALLBINS - SMALLBIN_CORRECTION) * SMALLBIN_WIDTH)
1459 #define in_smallbin_range(sz) \
1460 ((unsigned long) (sz) < (unsigned long) MIN_LARGE_SIZE)
1462 #define smallbin_index(sz) \
1463 ((SMALLBIN_WIDTH == 16 ? (((unsigned) (sz)) >> 4) : (((unsigned) (sz)) >> 3))\
1464 + SMALLBIN_CORRECTION)
1466 #define largebin_index_32(sz) \
1467 (((((unsigned long) (sz)) >> 6) <= 38) ? 56 + (((unsigned long) (sz)) >> 6) :\
1468 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1469 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1470 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1471 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1474 #define largebin_index_32_big(sz) \
1475 (((((unsigned long) (sz)) >> 6) <= 45) ? 49 + (((unsigned long) (sz)) >> 6) :\
1476 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1477 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1478 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1479 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1482 // XXX It remains to be seen whether it is good to keep the widths of
1483 // XXX the buckets the same or whether it should be scaled by a factor
1484 // XXX of two as well.
1485 #define largebin_index_64(sz) \
1486 (((((unsigned long) (sz)) >> 6) <= 48) ? 48 + (((unsigned long) (sz)) >> 6) :\
1487 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1488 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1489 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1490 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1493 #define largebin_index(sz) \
1494 (SIZE_SZ == 8 ? largebin_index_64 (sz) \
1495 : MALLOC_ALIGNMENT == 16 ? largebin_index_32_big (sz) \
1496 : largebin_index_32 (sz))
1498 #define bin_index(sz) \
1499 ((in_smallbin_range (sz)) ? smallbin_index (sz) : largebin_index (sz))
1505 All remainders from chunk splits, as well as all returned chunks,
1506 are first placed in the "unsorted" bin. They are then placed
1507 in regular bins after malloc gives them ONE chance to be used before
1508 binning. So, basically, the unsorted_chunks list acts as a queue,
1509 with chunks being placed on it in free (and malloc_consolidate),
1510 and taken off (to be either used or placed in bins) in malloc.
1512 The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
1513 does not have to be taken into account in size comparisons.
1516 /* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
1517 #define unsorted_chunks(M) (bin_at (M, 1))
1522 The top-most available chunk (i.e., the one bordering the end of
1523 available memory) is treated specially. It is never included in
1524 any bin, is used only if no other chunk is available, and is
1525 released back to the system if it is very large (see
1526 M_TRIM_THRESHOLD). Because top initially
1527 points to its own bin with initial zero size, thus forcing
1528 extension on the first malloc request, we avoid having any special
1529 code in malloc to check whether it even exists yet. But we still
1530 need to do so when getting memory from system, so we make
1531 initial_top treat the bin as a legal but unusable chunk during the
1532 interval between initialization and the first call to
1533 sysmalloc. (This is somewhat delicate, since it relies on
1534 the 2 preceding words to be zero during this interval as well.)
1537 /* Conveniently, the unsorted bin can be used as dummy top on first call */
1538 #define initial_top(M) (unsorted_chunks (M))
1543 To help compensate for the large number of bins, a one-level index
1544 structure is used for bin-by-bin searching. `binmap' is a
1545 bitvector recording whether bins are definitely empty so they can
1546 be skipped over during during traversals. The bits are NOT always
1547 cleared as soon as bins are empty, but instead only
1548 when they are noticed to be empty during traversal in malloc.
1551 /* Conservatively use 32 bits per map word, even if on 64bit system */
1552 #define BINMAPSHIFT 5
1553 #define BITSPERMAP (1U << BINMAPSHIFT)
1554 #define BINMAPSIZE (NBINS / BITSPERMAP)
1556 #define idx2block(i) ((i) >> BINMAPSHIFT)
1557 #define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT) - 1))))
1559 #define mark_bin(m, i) ((m)->binmap[idx2block (i)] |= idx2bit (i))
1560 #define unmark_bin(m, i) ((m)->binmap[idx2block (i)] &= ~(idx2bit (i)))
1561 #define get_binmap(m, i) ((m)->binmap[idx2block (i)] & idx2bit (i))
1566 An array of lists holding recently freed small chunks. Fastbins
1567 are not doubly linked. It is faster to single-link them, and
1568 since chunks are never removed from the middles of these lists,
1569 double linking is not necessary. Also, unlike regular bins, they
1570 are not even processed in FIFO order (they use faster LIFO) since
1571 ordering doesn't much matter in the transient contexts in which
1572 fastbins are normally used.
1574 Chunks in fastbins keep their inuse bit set, so they cannot
1575 be consolidated with other free chunks. malloc_consolidate
1576 releases all chunks in fastbins and consolidates them with
1580 typedef struct malloc_chunk
*mfastbinptr
;
1581 #define fastbin(ar_ptr, idx) ((ar_ptr)->fastbinsY[idx])
1583 /* offset 2 to use otherwise unindexable first 2 bins */
1584 #define fastbin_index(sz) \
1585 ((((unsigned int) (sz)) >> (SIZE_SZ == 8 ? 4 : 3)) - 2)
1588 /* The maximum fastbin request size we support */
1589 #define MAX_FAST_SIZE (80 * SIZE_SZ / 4)
1591 #define NFASTBINS (fastbin_index (request2size (MAX_FAST_SIZE)) + 1)
1594 FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
1595 that triggers automatic consolidation of possibly-surrounding
1596 fastbin chunks. This is a heuristic, so the exact value should not
1597 matter too much. It is defined at half the default trim threshold as a
1598 compromise heuristic to only attempt consolidation if it is likely
1599 to lead to trimming. However, it is not dynamically tunable, since
1600 consolidation reduces fragmentation surrounding large chunks even
1601 if trimming is not used.
1604 #define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
1607 NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
1608 regions. Otherwise, contiguity is exploited in merging together,
1609 when possible, results from consecutive MORECORE calls.
1611 The initial value comes from MORECORE_CONTIGUOUS, but is
1612 changed dynamically if mmap is ever used as an sbrk substitute.
1615 #define NONCONTIGUOUS_BIT (2U)
1617 #define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
1618 #define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
1619 #define set_noncontiguous(M) ((M)->flags |= NONCONTIGUOUS_BIT)
1620 #define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
1622 /* Maximum size of memory handled in fastbins. */
1623 static INTERNAL_SIZE_T global_max_fast
;
1626 Set value of max_fast.
1627 Use impossibly small value if 0.
1628 Precondition: there are no existing fastbin chunks in the main arena.
1629 Since do_check_malloc_state () checks this, we call malloc_consolidate ()
1630 before changing max_fast. Note other arenas will leak their fast bin
1631 entries if max_fast is reduced.
1634 #define set_max_fast(s) \
1635 global_max_fast = (((s) == 0) \
1636 ? SMALLBIN_WIDTH : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
1638 static inline INTERNAL_SIZE_T
1641 /* Tell the GCC optimizers that global_max_fast is never larger
1642 than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in
1643 _int_malloc after constant propagation of the size parameter.
1644 (The code never executes because malloc preserves the
1645 global_max_fast invariant, but the optimizers may not recognize
1647 if (global_max_fast
> MAX_FAST_SIZE
)
1648 __builtin_unreachable ();
1649 return global_max_fast
;
1653 ----------- Internal state representation and initialization -----------
1657 have_fastchunks indicates that there are probably some fastbin chunks.
1658 It is set true on entering a chunk into any fastbin, and cleared early in
1659 malloc_consolidate. The value is approximate since it may be set when there
1660 are no fastbin chunks, or it may be clear even if there are fastbin chunks
1661 available. Given it's sole purpose is to reduce number of redundant calls to
1662 malloc_consolidate, it does not affect correctness. As a result we can safely
1663 use relaxed atomic accesses.
1669 /* Serialize access. */
1670 __libc_lock_define (, mutex
);
1672 /* Flags (formerly in max_fast). */
1675 /* Set if the fastbin chunks contain recently inserted free blocks. */
1676 /* Note this is a bool but not all targets support atomics on booleans. */
1677 int have_fastchunks
;
1680 mfastbinptr fastbinsY
[NFASTBINS
];
1682 /* Base of the topmost chunk -- not otherwise kept in a bin */
1685 /* The remainder from the most recent split of a small request */
1686 mchunkptr last_remainder
;
1688 /* Normal bins packed as described above */
1689 mchunkptr bins
[NBINS
* 2 - 2];
1691 /* Bitmap of bins */
1692 unsigned int binmap
[BINMAPSIZE
];
1695 struct malloc_state
*next
;
1697 /* Linked list for free arenas. Access to this field is serialized
1698 by free_list_lock in arena.c. */
1699 struct malloc_state
*next_free
;
1701 /* Number of threads attached to this arena. 0 if the arena is on
1702 the free list. Access to this field is serialized by
1703 free_list_lock in arena.c. */
1704 INTERNAL_SIZE_T attached_threads
;
1706 /* Memory allocated from the system in this arena. */
1707 INTERNAL_SIZE_T system_mem
;
1708 INTERNAL_SIZE_T max_system_mem
;
1713 /* Tunable parameters */
1714 unsigned long trim_threshold
;
1715 INTERNAL_SIZE_T top_pad
;
1716 INTERNAL_SIZE_T mmap_threshold
;
1717 INTERNAL_SIZE_T arena_test
;
1718 INTERNAL_SIZE_T arena_max
;
1720 /* Memory map support */
1724 /* the mmap_threshold is dynamic, until the user sets
1725 it manually, at which point we need to disable any
1726 dynamic behavior. */
1727 int no_dyn_threshold
;
1730 INTERNAL_SIZE_T mmapped_mem
;
1731 INTERNAL_SIZE_T max_mmapped_mem
;
1733 /* First address handed out by MORECORE/sbrk. */
1737 /* Maximum number of buckets to use. */
1739 size_t tcache_max_bytes
;
1740 /* Maximum number of chunks in each bucket. */
1741 size_t tcache_count
;
1742 /* Maximum number of chunks to remove from the unsorted list, which
1743 aren't used to prefill the cache. */
1744 size_t tcache_unsorted_limit
;
1748 /* There are several instances of this struct ("arenas") in this
1749 malloc. If you are adapting this malloc in a way that does NOT use
1750 a static or mmapped malloc_state, you MUST explicitly zero-fill it
1751 before using. This malloc relies on the property that malloc_state
1752 is initialized to all zeroes (as is true of C statics). */
1754 static struct malloc_state main_arena
=
1756 .mutex
= _LIBC_LOCK_INITIALIZER
,
1757 .next
= &main_arena
,
1758 .attached_threads
= 1
1761 /* These variables are used for undumping support. Chunked are marked
1762 as using mmap, but we leave them alone if they fall into this
1763 range. NB: The chunk size for these chunks only includes the
1764 initial size field (of SIZE_SZ bytes), there is no trailing size
1765 field (unlike with regular mmapped chunks). */
1766 static mchunkptr dumped_main_arena_start
; /* Inclusive. */
1767 static mchunkptr dumped_main_arena_end
; /* Exclusive. */
1769 /* True if the pointer falls into the dumped arena. Use this after
1770 chunk_is_mmapped indicates a chunk is mmapped. */
1771 #define DUMPED_MAIN_ARENA_CHUNK(p) \
1772 ((p) >= dumped_main_arena_start && (p) < dumped_main_arena_end)
1774 /* There is only one instance of the malloc parameters. */
1776 static struct malloc_par mp_
=
1778 .top_pad
= DEFAULT_TOP_PAD
,
1779 .n_mmaps_max
= DEFAULT_MMAP_MAX
,
1780 .mmap_threshold
= DEFAULT_MMAP_THRESHOLD
,
1781 .trim_threshold
= DEFAULT_TRIM_THRESHOLD
,
1782 #define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8))
1783 .arena_test
= NARENAS_FROM_NCORES (1)
1786 .tcache_count
= TCACHE_FILL_COUNT
,
1787 .tcache_bins
= TCACHE_MAX_BINS
,
1788 .tcache_max_bytes
= tidx2usize (TCACHE_MAX_BINS
-1),
1789 .tcache_unsorted_limit
= 0 /* No limit. */
1794 Initialize a malloc_state struct.
1796 This is called from ptmalloc_init () or from _int_new_arena ()
1797 when creating a new arena.
1801 malloc_init_state (mstate av
)
1806 /* Establish circular links for normal bins */
1807 for (i
= 1; i
< NBINS
; ++i
)
1809 bin
= bin_at (av
, i
);
1810 bin
->fd
= bin
->bk
= bin
;
1813 #if MORECORE_CONTIGUOUS
1814 if (av
!= &main_arena
)
1816 set_noncontiguous (av
);
1817 if (av
== &main_arena
)
1818 set_max_fast (DEFAULT_MXFAST
);
1819 atomic_store_relaxed (&av
->have_fastchunks
, false);
1821 av
->top
= initial_top (av
);
1825 Other internal utilities operating on mstates
1828 static void *sysmalloc (INTERNAL_SIZE_T
, mstate
);
1829 static int systrim (size_t, mstate
);
1830 static void malloc_consolidate (mstate
);
1833 /* -------------- Early definitions for debugging hooks ---------------- */
1835 /* Define and initialize the hook variables. These weak definitions must
1836 appear before any use of the variables in a function (arena.c uses one). */
1837 #ifndef weak_variable
1838 /* In GNU libc we want the hook variables to be weak definitions to
1839 avoid a problem with Emacs. */
1840 # define weak_variable weak_function
1843 /* Forward declarations. */
1844 static void *malloc_hook_ini (size_t sz
,
1845 const void *caller
) __THROW
;
1846 static void *realloc_hook_ini (void *ptr
, size_t sz
,
1847 const void *caller
) __THROW
;
1848 static void *memalign_hook_ini (size_t alignment
, size_t sz
,
1849 const void *caller
) __THROW
;
1851 #if HAVE_MALLOC_INIT_HOOK
1852 void weak_variable (*__malloc_initialize_hook
) (void) = NULL
;
1853 compat_symbol (libc
, __malloc_initialize_hook
,
1854 __malloc_initialize_hook
, GLIBC_2_0
);
1857 void weak_variable (*__free_hook
) (void *__ptr
,
1858 const void *) = NULL
;
1859 void *weak_variable (*__malloc_hook
)
1860 (size_t __size
, const void *) = malloc_hook_ini
;
1861 void *weak_variable (*__realloc_hook
)
1862 (void *__ptr
, size_t __size
, const void *)
1864 void *weak_variable (*__memalign_hook
)
1865 (size_t __alignment
, size_t __size
, const void *)
1866 = memalign_hook_ini
;
1867 void weak_variable (*__after_morecore_hook
) (void) = NULL
;
1870 /* ------------------ Testing support ----------------------------------*/
1872 static int perturb_byte
;
1875 alloc_perturb (char *p
, size_t n
)
1877 if (__glibc_unlikely (perturb_byte
))
1878 memset (p
, perturb_byte
^ 0xff, n
);
1882 free_perturb (char *p
, size_t n
)
1884 if (__glibc_unlikely (perturb_byte
))
1885 memset (p
, perturb_byte
, n
);
1890 #include <stap-probe.h>
1892 /* ------------------- Support for multiple arenas -------------------- */
1898 These routines make a number of assertions about the states
1899 of data structures that should be true at all times. If any
1900 are not true, it's very likely that a user program has somehow
1901 trashed memory. (It's also possible that there is a coding error
1902 in malloc. In which case, please report it!)
1907 # define check_chunk(A, P)
1908 # define check_free_chunk(A, P)
1909 # define check_inuse_chunk(A, P)
1910 # define check_remalloced_chunk(A, P, N)
1911 # define check_malloced_chunk(A, P, N)
1912 # define check_malloc_state(A)
1916 # define check_chunk(A, P) do_check_chunk (A, P)
1917 # define check_free_chunk(A, P) do_check_free_chunk (A, P)
1918 # define check_inuse_chunk(A, P) do_check_inuse_chunk (A, P)
1919 # define check_remalloced_chunk(A, P, N) do_check_remalloced_chunk (A, P, N)
1920 # define check_malloced_chunk(A, P, N) do_check_malloced_chunk (A, P, N)
1921 # define check_malloc_state(A) do_check_malloc_state (A)
1924 Properties of all chunks
1928 do_check_chunk (mstate av
, mchunkptr p
)
1930 unsigned long sz
= chunksize (p
);
1931 /* min and max possible addresses assuming contiguous allocation */
1932 char *max_address
= (char *) (av
->top
) + chunksize (av
->top
);
1933 char *min_address
= max_address
- av
->system_mem
;
1935 if (!chunk_is_mmapped (p
))
1937 /* Has legal address ... */
1940 if (contiguous (av
))
1942 assert (((char *) p
) >= min_address
);
1943 assert (((char *) p
+ sz
) <= ((char *) (av
->top
)));
1948 /* top size is always at least MINSIZE */
1949 assert ((unsigned long) (sz
) >= MINSIZE
);
1950 /* top predecessor always marked inuse */
1951 assert (prev_inuse (p
));
1954 else if (!DUMPED_MAIN_ARENA_CHUNK (p
))
1956 /* address is outside main heap */
1957 if (contiguous (av
) && av
->top
!= initial_top (av
))
1959 assert (((char *) p
) < min_address
|| ((char *) p
) >= max_address
);
1961 /* chunk is page-aligned */
1962 assert (((prev_size (p
) + sz
) & (GLRO (dl_pagesize
) - 1)) == 0);
1963 /* mem is aligned */
1964 assert (aligned_OK (chunk2mem (p
)));
1969 Properties of free chunks
1973 do_check_free_chunk (mstate av
, mchunkptr p
)
1975 INTERNAL_SIZE_T sz
= chunksize_nomask (p
) & ~(PREV_INUSE
| NON_MAIN_ARENA
);
1976 mchunkptr next
= chunk_at_offset (p
, sz
);
1978 do_check_chunk (av
, p
);
1980 /* Chunk must claim to be free ... */
1981 assert (!inuse (p
));
1982 assert (!chunk_is_mmapped (p
));
1984 /* Unless a special marker, must have OK fields */
1985 if ((unsigned long) (sz
) >= MINSIZE
)
1987 assert ((sz
& MALLOC_ALIGN_MASK
) == 0);
1988 assert (aligned_OK (chunk2mem (p
)));
1989 /* ... matching footer field */
1990 assert (prev_size (next_chunk (p
)) == sz
);
1991 /* ... and is fully consolidated */
1992 assert (prev_inuse (p
));
1993 assert (next
== av
->top
|| inuse (next
));
1995 /* ... and has minimally sane links */
1996 assert (p
->fd
->bk
== p
);
1997 assert (p
->bk
->fd
== p
);
1999 else /* markers are always of size SIZE_SZ */
2000 assert (sz
== SIZE_SZ
);
2004 Properties of inuse chunks
2008 do_check_inuse_chunk (mstate av
, mchunkptr p
)
2012 do_check_chunk (av
, p
);
2014 if (chunk_is_mmapped (p
))
2015 return; /* mmapped chunks have no next/prev */
2017 /* Check whether it claims to be in use ... */
2020 next
= next_chunk (p
);
2022 /* ... and is surrounded by OK chunks.
2023 Since more things can be checked with free chunks than inuse ones,
2024 if an inuse chunk borders them and debug is on, it's worth doing them.
2026 if (!prev_inuse (p
))
2028 /* Note that we cannot even look at prev unless it is not inuse */
2029 mchunkptr prv
= prev_chunk (p
);
2030 assert (next_chunk (prv
) == p
);
2031 do_check_free_chunk (av
, prv
);
2034 if (next
== av
->top
)
2036 assert (prev_inuse (next
));
2037 assert (chunksize (next
) >= MINSIZE
);
2039 else if (!inuse (next
))
2040 do_check_free_chunk (av
, next
);
2044 Properties of chunks recycled from fastbins
2048 do_check_remalloced_chunk (mstate av
, mchunkptr p
, INTERNAL_SIZE_T s
)
2050 INTERNAL_SIZE_T sz
= chunksize_nomask (p
) & ~(PREV_INUSE
| NON_MAIN_ARENA
);
2052 if (!chunk_is_mmapped (p
))
2054 assert (av
== arena_for_chunk (p
));
2055 if (chunk_main_arena (p
))
2056 assert (av
== &main_arena
);
2058 assert (av
!= &main_arena
);
2061 do_check_inuse_chunk (av
, p
);
2063 /* Legal size ... */
2064 assert ((sz
& MALLOC_ALIGN_MASK
) == 0);
2065 assert ((unsigned long) (sz
) >= MINSIZE
);
2066 /* ... and alignment */
2067 assert (aligned_OK (chunk2mem (p
)));
2068 /* chunk is less than MINSIZE more than request */
2069 assert ((long) (sz
) - (long) (s
) >= 0);
2070 assert ((long) (sz
) - (long) (s
+ MINSIZE
) < 0);
2074 Properties of nonrecycled chunks at the point they are malloced
2078 do_check_malloced_chunk (mstate av
, mchunkptr p
, INTERNAL_SIZE_T s
)
2080 /* same as recycled case ... */
2081 do_check_remalloced_chunk (av
, p
, s
);
2084 ... plus, must obey implementation invariant that prev_inuse is
2085 always true of any allocated chunk; i.e., that each allocated
2086 chunk borders either a previously allocated and still in-use
2087 chunk, or the base of its memory arena. This is ensured
2088 by making all allocations from the `lowest' part of any found
2089 chunk. This does not necessarily hold however for chunks
2090 recycled via fastbins.
2093 assert (prev_inuse (p
));
2098 Properties of malloc_state.
2100 This may be useful for debugging malloc, as well as detecting user
2101 programmer errors that somehow write into malloc_state.
2103 If you are extending or experimenting with this malloc, you can
2104 probably figure out how to hack this routine to print out or
2105 display chunk addresses, sizes, bins, and other instrumentation.
2109 do_check_malloc_state (mstate av
)
2116 INTERNAL_SIZE_T size
;
2117 unsigned long total
= 0;
2120 /* internal size_t must be no wider than pointer type */
2121 assert (sizeof (INTERNAL_SIZE_T
) <= sizeof (char *));
2123 /* alignment is a power of 2 */
2124 assert ((MALLOC_ALIGNMENT
& (MALLOC_ALIGNMENT
- 1)) == 0);
2126 /* Check the arena is initialized. */
2127 assert (av
->top
!= 0);
2129 /* No memory has been allocated yet, so doing more tests is not possible. */
2130 if (av
->top
== initial_top (av
))
2133 /* pagesize is a power of 2 */
2134 assert (powerof2(GLRO (dl_pagesize
)));
2136 /* A contiguous main_arena is consistent with sbrk_base. */
2137 if (av
== &main_arena
&& contiguous (av
))
2138 assert ((char *) mp_
.sbrk_base
+ av
->system_mem
==
2139 (char *) av
->top
+ chunksize (av
->top
));
2141 /* properties of fastbins */
2143 /* max_fast is in allowed range */
2144 assert ((get_max_fast () & ~1) <= request2size (MAX_FAST_SIZE
));
2146 max_fast_bin
= fastbin_index (get_max_fast ());
2148 for (i
= 0; i
< NFASTBINS
; ++i
)
2150 p
= fastbin (av
, i
);
2152 /* The following test can only be performed for the main arena.
2153 While mallopt calls malloc_consolidate to get rid of all fast
2154 bins (especially those larger than the new maximum) this does
2155 only happen for the main arena. Trying to do this for any
2156 other arena would mean those arenas have to be locked and
2157 malloc_consolidate be called for them. This is excessive. And
2158 even if this is acceptable to somebody it still cannot solve
2159 the problem completely since if the arena is locked a
2160 concurrent malloc call might create a new arena which then
2161 could use the newly invalid fast bins. */
2163 /* all bins past max_fast are empty */
2164 if (av
== &main_arena
&& i
> max_fast_bin
)
2169 /* each chunk claims to be inuse */
2170 do_check_inuse_chunk (av
, p
);
2171 total
+= chunksize (p
);
2172 /* chunk belongs in this bin */
2173 assert (fastbin_index (chunksize (p
)) == i
);
2178 /* check normal bins */
2179 for (i
= 1; i
< NBINS
; ++i
)
2183 /* binmap is accurate (except for bin 1 == unsorted_chunks) */
2186 unsigned int binbit
= get_binmap (av
, i
);
2187 int empty
= last (b
) == b
;
2194 for (p
= last (b
); p
!= b
; p
= p
->bk
)
2196 /* each chunk claims to be free */
2197 do_check_free_chunk (av
, p
);
2198 size
= chunksize (p
);
2202 /* chunk belongs in bin */
2203 idx
= bin_index (size
);
2205 /* lists are sorted */
2206 assert (p
->bk
== b
||
2207 (unsigned long) chunksize (p
->bk
) >= (unsigned long) chunksize (p
));
2209 if (!in_smallbin_range (size
))
2211 if (p
->fd_nextsize
!= NULL
)
2213 if (p
->fd_nextsize
== p
)
2214 assert (p
->bk_nextsize
== p
);
2217 if (p
->fd_nextsize
== first (b
))
2218 assert (chunksize (p
) < chunksize (p
->fd_nextsize
));
2220 assert (chunksize (p
) > chunksize (p
->fd_nextsize
));
2223 assert (chunksize (p
) > chunksize (p
->bk_nextsize
));
2225 assert (chunksize (p
) < chunksize (p
->bk_nextsize
));
2229 assert (p
->bk_nextsize
== NULL
);
2232 else if (!in_smallbin_range (size
))
2233 assert (p
->fd_nextsize
== NULL
&& p
->bk_nextsize
== NULL
);
2234 /* chunk is followed by a legal chain of inuse chunks */
2235 for (q
= next_chunk (p
);
2236 (q
!= av
->top
&& inuse (q
) &&
2237 (unsigned long) (chunksize (q
)) >= MINSIZE
);
2239 do_check_inuse_chunk (av
, q
);
2243 /* top chunk is OK */
2244 check_chunk (av
, av
->top
);
2249 /* ----------------- Support for debugging hooks -------------------- */
2253 /* ----------- Routines dealing with system allocation -------------- */
2256 sysmalloc handles malloc cases requiring more memory from the system.
2257 On entry, it is assumed that av->top does not have enough
2258 space to service request for nb bytes, thus requiring that av->top
2259 be extended or replaced.
2263 sysmalloc (INTERNAL_SIZE_T nb
, mstate av
)
2265 mchunkptr old_top
; /* incoming value of av->top */
2266 INTERNAL_SIZE_T old_size
; /* its size */
2267 char *old_end
; /* its end address */
2269 long size
; /* arg to first MORECORE or mmap call */
2270 char *brk
; /* return value from MORECORE */
2272 long correction
; /* arg to 2nd MORECORE call */
2273 char *snd_brk
; /* 2nd return val */
2275 INTERNAL_SIZE_T front_misalign
; /* unusable bytes at front of new space */
2276 INTERNAL_SIZE_T end_misalign
; /* partial page left at end of new space */
2277 char *aligned_brk
; /* aligned offset into brk */
2279 mchunkptr p
; /* the allocated/returned chunk */
2280 mchunkptr remainder
; /* remainder from allocation */
2281 unsigned long remainder_size
; /* its size */
2284 size_t pagesize
= GLRO (dl_pagesize
);
2285 bool tried_mmap
= false;
2289 If have mmap, and the request size meets the mmap threshold, and
2290 the system supports mmap, and there are few enough currently
2291 allocated mmapped regions, try to directly map this request
2292 rather than expanding top.
2296 || ((unsigned long) (nb
) >= (unsigned long) (mp_
.mmap_threshold
)
2297 && (mp_
.n_mmaps
< mp_
.n_mmaps_max
)))
2299 char *mm
; /* return value from mmap call*/
2303 Round up size to nearest page. For mmapped chunks, the overhead
2304 is one SIZE_SZ unit larger than for normal chunks, because there
2305 is no following chunk whose prev_size field could be used.
2307 See the front_misalign handling below, for glibc there is no
2308 need for further alignments unless we have have high alignment.
2310 if (MALLOC_ALIGNMENT
== 2 * SIZE_SZ
)
2311 size
= ALIGN_UP (nb
+ SIZE_SZ
, pagesize
);
2313 size
= ALIGN_UP (nb
+ SIZE_SZ
+ MALLOC_ALIGN_MASK
, pagesize
);
2316 /* Don't try if size wraps around 0 */
2317 if ((unsigned long) (size
) > (unsigned long) (nb
))
2319 mm
= (char *) (MMAP (0, size
, PROT_READ
| PROT_WRITE
, 0));
2321 if (mm
!= MAP_FAILED
)
2324 The offset to the start of the mmapped region is stored
2325 in the prev_size field of the chunk. This allows us to adjust
2326 returned start address to meet alignment requirements here
2327 and in memalign(), and still be able to compute proper
2328 address argument for later munmap in free() and realloc().
2331 if (MALLOC_ALIGNMENT
== 2 * SIZE_SZ
)
2333 /* For glibc, chunk2mem increases the address by 2*SIZE_SZ and
2334 MALLOC_ALIGN_MASK is 2*SIZE_SZ-1. Each mmap'ed area is page
2335 aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. */
2336 assert (((INTERNAL_SIZE_T
) chunk2mem (mm
) & MALLOC_ALIGN_MASK
) == 0);
2340 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (mm
) & MALLOC_ALIGN_MASK
;
2341 if (front_misalign
> 0)
2343 correction
= MALLOC_ALIGNMENT
- front_misalign
;
2344 p
= (mchunkptr
) (mm
+ correction
);
2345 set_prev_size (p
, correction
);
2346 set_head (p
, (size
- correction
) | IS_MMAPPED
);
2351 set_prev_size (p
, 0);
2352 set_head (p
, size
| IS_MMAPPED
);
2355 /* update statistics */
2357 int new = atomic_exchange_and_add (&mp_
.n_mmaps
, 1) + 1;
2358 atomic_max (&mp_
.max_n_mmaps
, new);
2361 sum
= atomic_exchange_and_add (&mp_
.mmapped_mem
, size
) + size
;
2362 atomic_max (&mp_
.max_mmapped_mem
, sum
);
2364 check_chunk (av
, p
);
2366 return chunk2mem (p
);
2371 /* There are no usable arenas and mmap also failed. */
2375 /* Record incoming configuration of top */
2378 old_size
= chunksize (old_top
);
2379 old_end
= (char *) (chunk_at_offset (old_top
, old_size
));
2381 brk
= snd_brk
= (char *) (MORECORE_FAILURE
);
2384 If not the first time through, we require old_size to be
2385 at least MINSIZE and to have prev_inuse set.
2388 assert ((old_top
== initial_top (av
) && old_size
== 0) ||
2389 ((unsigned long) (old_size
) >= MINSIZE
&&
2390 prev_inuse (old_top
) &&
2391 ((unsigned long) old_end
& (pagesize
- 1)) == 0));
2393 /* Precondition: not enough current space to satisfy nb request */
2394 assert ((unsigned long) (old_size
) < (unsigned long) (nb
+ MINSIZE
));
2397 if (av
!= &main_arena
)
2399 heap_info
*old_heap
, *heap
;
2400 size_t old_heap_size
;
2402 /* First try to extend the current heap. */
2403 old_heap
= heap_for_ptr (old_top
);
2404 old_heap_size
= old_heap
->size
;
2405 if ((long) (MINSIZE
+ nb
- old_size
) > 0
2406 && grow_heap (old_heap
, MINSIZE
+ nb
- old_size
) == 0)
2408 av
->system_mem
+= old_heap
->size
- old_heap_size
;
2409 set_head (old_top
, (((char *) old_heap
+ old_heap
->size
) - (char *) old_top
)
2412 else if ((heap
= new_heap (nb
+ (MINSIZE
+ sizeof (*heap
)), mp_
.top_pad
)))
2414 /* Use a newly allocated heap. */
2416 heap
->prev
= old_heap
;
2417 av
->system_mem
+= heap
->size
;
2418 /* Set up the new top. */
2419 top (av
) = chunk_at_offset (heap
, sizeof (*heap
));
2420 set_head (top (av
), (heap
->size
- sizeof (*heap
)) | PREV_INUSE
);
2422 /* Setup fencepost and free the old top chunk with a multiple of
2423 MALLOC_ALIGNMENT in size. */
2424 /* The fencepost takes at least MINSIZE bytes, because it might
2425 become the top chunk again later. Note that a footer is set
2426 up, too, although the chunk is marked in use. */
2427 old_size
= (old_size
- MINSIZE
) & ~MALLOC_ALIGN_MASK
;
2428 set_head (chunk_at_offset (old_top
, old_size
+ 2 * SIZE_SZ
), 0 | PREV_INUSE
);
2429 if (old_size
>= MINSIZE
)
2431 set_head (chunk_at_offset (old_top
, old_size
), (2 * SIZE_SZ
) | PREV_INUSE
);
2432 set_foot (chunk_at_offset (old_top
, old_size
), (2 * SIZE_SZ
));
2433 set_head (old_top
, old_size
| PREV_INUSE
| NON_MAIN_ARENA
);
2434 _int_free (av
, old_top
, 1);
2438 set_head (old_top
, (old_size
+ 2 * SIZE_SZ
) | PREV_INUSE
);
2439 set_foot (old_top
, (old_size
+ 2 * SIZE_SZ
));
2442 else if (!tried_mmap
)
2443 /* We can at least try to use to mmap memory. */
2446 else /* av == main_arena */
2449 { /* Request enough space for nb + pad + overhead */
2450 size
= nb
+ mp_
.top_pad
+ MINSIZE
;
2453 If contiguous, we can subtract out existing space that we hope to
2454 combine with new space. We add it back later only if
2455 we don't actually get contiguous space.
2458 if (contiguous (av
))
2462 Round to a multiple of page size.
2463 If MORECORE is not contiguous, this ensures that we only call it
2464 with whole-page arguments. And if MORECORE is contiguous and
2465 this is not first time through, this preserves page-alignment of
2466 previous calls. Otherwise, we correct to page-align below.
2469 size
= ALIGN_UP (size
, pagesize
);
2472 Don't try to call MORECORE if argument is so big as to appear
2473 negative. Note that since mmap takes size_t arg, it may succeed
2474 below even if we cannot call MORECORE.
2479 brk
= (char *) (MORECORE (size
));
2480 LIBC_PROBE (memory_sbrk_more
, 2, brk
, size
);
2483 if (brk
!= (char *) (MORECORE_FAILURE
))
2485 /* Call the `morecore' hook if necessary. */
2486 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2487 if (__builtin_expect (hook
!= NULL
, 0))
2493 If have mmap, try using it as a backup when MORECORE fails or
2494 cannot be used. This is worth doing on systems that have "holes" in
2495 address space, so sbrk cannot extend to give contiguous space, but
2496 space is available elsewhere. Note that we ignore mmap max count
2497 and threshold limits, since the space will not be used as a
2498 segregated mmap region.
2501 /* Cannot merge with old top, so add its size back in */
2502 if (contiguous (av
))
2503 size
= ALIGN_UP (size
+ old_size
, pagesize
);
2505 /* If we are relying on mmap as backup, then use larger units */
2506 if ((unsigned long) (size
) < (unsigned long) (MMAP_AS_MORECORE_SIZE
))
2507 size
= MMAP_AS_MORECORE_SIZE
;
2509 /* Don't try if size wraps around 0 */
2510 if ((unsigned long) (size
) > (unsigned long) (nb
))
2512 char *mbrk
= (char *) (MMAP (0, size
, PROT_READ
| PROT_WRITE
, 0));
2514 if (mbrk
!= MAP_FAILED
)
2516 /* We do not need, and cannot use, another sbrk call to find end */
2518 snd_brk
= brk
+ size
;
2521 Record that we no longer have a contiguous sbrk region.
2522 After the first time mmap is used as backup, we do not
2523 ever rely on contiguous space since this could incorrectly
2526 set_noncontiguous (av
);
2531 if (brk
!= (char *) (MORECORE_FAILURE
))
2533 if (mp_
.sbrk_base
== 0)
2534 mp_
.sbrk_base
= brk
;
2535 av
->system_mem
+= size
;
2538 If MORECORE extends previous space, we can likewise extend top size.
2541 if (brk
== old_end
&& snd_brk
== (char *) (MORECORE_FAILURE
))
2542 set_head (old_top
, (size
+ old_size
) | PREV_INUSE
);
2544 else if (contiguous (av
) && old_size
&& brk
< old_end
)
2545 /* Oops! Someone else killed our space.. Can't touch anything. */
2546 malloc_printerr ("break adjusted to free malloc space");
2549 Otherwise, make adjustments:
2551 * If the first time through or noncontiguous, we need to call sbrk
2552 just to find out where the end of memory lies.
2554 * We need to ensure that all returned chunks from malloc will meet
2557 * If there was an intervening foreign sbrk, we need to adjust sbrk
2558 request size to account for fact that we will not be able to
2559 combine new space with existing space in old_top.
2561 * Almost all systems internally allocate whole pages at a time, in
2562 which case we might as well use the whole last page of request.
2563 So we allocate enough more memory to hit a page boundary now,
2564 which in turn causes future contiguous calls to page-align.
2574 /* handle contiguous cases */
2575 if (contiguous (av
))
2577 /* Count foreign sbrk as system_mem. */
2579 av
->system_mem
+= brk
- old_end
;
2581 /* Guarantee alignment of first new chunk made from this space */
2583 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (brk
) & MALLOC_ALIGN_MASK
;
2584 if (front_misalign
> 0)
2587 Skip over some bytes to arrive at an aligned position.
2588 We don't need to specially mark these wasted front bytes.
2589 They will never be accessed anyway because
2590 prev_inuse of av->top (and any chunk created from its start)
2591 is always true after initialization.
2594 correction
= MALLOC_ALIGNMENT
- front_misalign
;
2595 aligned_brk
+= correction
;
2599 If this isn't adjacent to existing space, then we will not
2600 be able to merge with old_top space, so must add to 2nd request.
2603 correction
+= old_size
;
2605 /* Extend the end address to hit a page boundary */
2606 end_misalign
= (INTERNAL_SIZE_T
) (brk
+ size
+ correction
);
2607 correction
+= (ALIGN_UP (end_misalign
, pagesize
)) - end_misalign
;
2609 assert (correction
>= 0);
2610 snd_brk
= (char *) (MORECORE (correction
));
2613 If can't allocate correction, try to at least find out current
2614 brk. It might be enough to proceed without failing.
2616 Note that if second sbrk did NOT fail, we assume that space
2617 is contiguous with first sbrk. This is a safe assumption unless
2618 program is multithreaded but doesn't use locks and a foreign sbrk
2619 occurred between our first and second calls.
2622 if (snd_brk
== (char *) (MORECORE_FAILURE
))
2625 snd_brk
= (char *) (MORECORE (0));
2629 /* Call the `morecore' hook if necessary. */
2630 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2631 if (__builtin_expect (hook
!= NULL
, 0))
2636 /* handle non-contiguous cases */
2639 if (MALLOC_ALIGNMENT
== 2 * SIZE_SZ
)
2640 /* MORECORE/mmap must correctly align */
2641 assert (((unsigned long) chunk2mem (brk
) & MALLOC_ALIGN_MASK
) == 0);
2644 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (brk
) & MALLOC_ALIGN_MASK
;
2645 if (front_misalign
> 0)
2648 Skip over some bytes to arrive at an aligned position.
2649 We don't need to specially mark these wasted front bytes.
2650 They will never be accessed anyway because
2651 prev_inuse of av->top (and any chunk created from its start)
2652 is always true after initialization.
2655 aligned_brk
+= MALLOC_ALIGNMENT
- front_misalign
;
2659 /* Find out current end of memory */
2660 if (snd_brk
== (char *) (MORECORE_FAILURE
))
2662 snd_brk
= (char *) (MORECORE (0));
2666 /* Adjust top based on results of second sbrk */
2667 if (snd_brk
!= (char *) (MORECORE_FAILURE
))
2669 av
->top
= (mchunkptr
) aligned_brk
;
2670 set_head (av
->top
, (snd_brk
- aligned_brk
+ correction
) | PREV_INUSE
);
2671 av
->system_mem
+= correction
;
2674 If not the first time through, we either have a
2675 gap due to foreign sbrk or a non-contiguous region. Insert a
2676 double fencepost at old_top to prevent consolidation with space
2677 we don't own. These fenceposts are artificial chunks that are
2678 marked as inuse and are in any case too small to use. We need
2679 two to make sizes and alignments work out.
2685 Shrink old_top to insert fenceposts, keeping size a
2686 multiple of MALLOC_ALIGNMENT. We know there is at least
2687 enough space in old_top to do this.
2689 old_size
= (old_size
- 4 * SIZE_SZ
) & ~MALLOC_ALIGN_MASK
;
2690 set_head (old_top
, old_size
| PREV_INUSE
);
2693 Note that the following assignments completely overwrite
2694 old_top when old_size was previously MINSIZE. This is
2695 intentional. We need the fencepost, even if old_top otherwise gets
2698 set_head (chunk_at_offset (old_top
, old_size
),
2699 (2 * SIZE_SZ
) | PREV_INUSE
);
2700 set_head (chunk_at_offset (old_top
, old_size
+ 2 * SIZE_SZ
),
2701 (2 * SIZE_SZ
) | PREV_INUSE
);
2703 /* If possible, release the rest. */
2704 if (old_size
>= MINSIZE
)
2706 _int_free (av
, old_top
, 1);
2712 } /* if (av != &main_arena) */
2714 if ((unsigned long) av
->system_mem
> (unsigned long) (av
->max_system_mem
))
2715 av
->max_system_mem
= av
->system_mem
;
2716 check_malloc_state (av
);
2718 /* finally, do the allocation */
2720 size
= chunksize (p
);
2722 /* check that one of the above allocation paths succeeded */
2723 if ((unsigned long) (size
) >= (unsigned long) (nb
+ MINSIZE
))
2725 remainder_size
= size
- nb
;
2726 remainder
= chunk_at_offset (p
, nb
);
2727 av
->top
= remainder
;
2728 set_head (p
, nb
| PREV_INUSE
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
2729 set_head (remainder
, remainder_size
| PREV_INUSE
);
2730 check_malloced_chunk (av
, p
, nb
);
2731 return chunk2mem (p
);
2734 /* catch all failure paths */
2735 __set_errno (ENOMEM
);
2741 systrim is an inverse of sorts to sysmalloc. It gives memory back
2742 to the system (via negative arguments to sbrk) if there is unused
2743 memory at the `high' end of the malloc pool. It is called
2744 automatically by free() when top space exceeds the trim
2745 threshold. It is also called by the public malloc_trim routine. It
2746 returns 1 if it actually released any memory, else 0.
2750 systrim (size_t pad
, mstate av
)
2752 long top_size
; /* Amount of top-most memory */
2753 long extra
; /* Amount to release */
2754 long released
; /* Amount actually released */
2755 char *current_brk
; /* address returned by pre-check sbrk call */
2756 char *new_brk
; /* address returned by post-check sbrk call */
2760 pagesize
= GLRO (dl_pagesize
);
2761 top_size
= chunksize (av
->top
);
2763 top_area
= top_size
- MINSIZE
- 1;
2764 if (top_area
<= pad
)
2767 /* Release in pagesize units and round down to the nearest page. */
2768 extra
= ALIGN_DOWN(top_area
- pad
, pagesize
);
2774 Only proceed if end of memory is where we last set it.
2775 This avoids problems if there were foreign sbrk calls.
2777 current_brk
= (char *) (MORECORE (0));
2778 if (current_brk
== (char *) (av
->top
) + top_size
)
2781 Attempt to release memory. We ignore MORECORE return value,
2782 and instead call again to find out where new end of memory is.
2783 This avoids problems if first call releases less than we asked,
2784 of if failure somehow altered brk value. (We could still
2785 encounter problems if it altered brk in some very bad way,
2786 but the only thing we can do is adjust anyway, which will cause
2787 some downstream failure.)
2791 /* Call the `morecore' hook if necessary. */
2792 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2793 if (__builtin_expect (hook
!= NULL
, 0))
2795 new_brk
= (char *) (MORECORE (0));
2797 LIBC_PROBE (memory_sbrk_less
, 2, new_brk
, extra
);
2799 if (new_brk
!= (char *) MORECORE_FAILURE
)
2801 released
= (long) (current_brk
- new_brk
);
2805 /* Success. Adjust top. */
2806 av
->system_mem
-= released
;
2807 set_head (av
->top
, (top_size
- released
) | PREV_INUSE
);
2808 check_malloc_state (av
);
2817 munmap_chunk (mchunkptr p
)
2819 INTERNAL_SIZE_T size
= chunksize (p
);
2821 assert (chunk_is_mmapped (p
));
2823 /* Do nothing if the chunk is a faked mmapped chunk in the dumped
2824 main arena. We never free this memory. */
2825 if (DUMPED_MAIN_ARENA_CHUNK (p
))
2828 uintptr_t block
= (uintptr_t) p
- prev_size (p
);
2829 size_t total_size
= prev_size (p
) + size
;
2830 /* Unfortunately we have to do the compilers job by hand here. Normally
2831 we would test BLOCK and TOTAL-SIZE separately for compliance with the
2832 page size. But gcc does not recognize the optimization possibility
2833 (in the moment at least) so we combine the two values into one before
2835 if (__builtin_expect (((block
| total_size
) & (GLRO (dl_pagesize
) - 1)) != 0, 0))
2836 malloc_printerr ("munmap_chunk(): invalid pointer");
2838 atomic_decrement (&mp_
.n_mmaps
);
2839 atomic_add (&mp_
.mmapped_mem
, -total_size
);
2841 /* If munmap failed the process virtual memory address space is in a
2842 bad shape. Just leave the block hanging around, the process will
2843 terminate shortly anyway since not much can be done. */
2844 __munmap ((char *) block
, total_size
);
2850 mremap_chunk (mchunkptr p
, size_t new_size
)
2852 size_t pagesize
= GLRO (dl_pagesize
);
2853 INTERNAL_SIZE_T offset
= prev_size (p
);
2854 INTERNAL_SIZE_T size
= chunksize (p
);
2857 assert (chunk_is_mmapped (p
));
2858 assert (((size
+ offset
) & (GLRO (dl_pagesize
) - 1)) == 0);
2860 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
2861 new_size
= ALIGN_UP (new_size
+ offset
+ SIZE_SZ
, pagesize
);
2863 /* No need to remap if the number of pages does not change. */
2864 if (size
+ offset
== new_size
)
2867 cp
= (char *) __mremap ((char *) p
- offset
, size
+ offset
, new_size
,
2870 if (cp
== MAP_FAILED
)
2873 p
= (mchunkptr
) (cp
+ offset
);
2875 assert (aligned_OK (chunk2mem (p
)));
2877 assert (prev_size (p
) == offset
);
2878 set_head (p
, (new_size
- offset
) | IS_MMAPPED
);
2880 INTERNAL_SIZE_T
new;
2881 new = atomic_exchange_and_add (&mp_
.mmapped_mem
, new_size
- size
- offset
)
2882 + new_size
- size
- offset
;
2883 atomic_max (&mp_
.max_mmapped_mem
, new);
2886 #endif /* HAVE_MREMAP */
2888 /*------------------------ Public wrappers. --------------------------------*/
2892 /* We overlay this structure on the user-data portion of a chunk when
2893 the chunk is stored in the per-thread cache. */
2894 typedef struct tcache_entry
2896 struct tcache_entry
*next
;
2899 /* There is one of these for each thread, which contains the
2900 per-thread cache (hence "tcache_perthread_struct"). Keeping
2901 overall size low is mildly important. Note that COUNTS and ENTRIES
2902 are redundant (we could have just counted the linked list each
2903 time), this is for performance reasons. */
2904 typedef struct tcache_perthread_struct
2906 char counts
[TCACHE_MAX_BINS
];
2907 tcache_entry
*entries
[TCACHE_MAX_BINS
];
2908 } tcache_perthread_struct
;
2910 static __thread
bool tcache_shutting_down
= false;
2911 static __thread tcache_perthread_struct
*tcache
= NULL
;
2913 /* Caller must ensure that we know tc_idx is valid and there's room
2915 static __always_inline
void
2916 tcache_put (mchunkptr chunk
, size_t tc_idx
)
2918 tcache_entry
*e
= (tcache_entry
*) chunk2mem (chunk
);
2919 assert (tc_idx
< TCACHE_MAX_BINS
);
2920 e
->next
= tcache
->entries
[tc_idx
];
2921 tcache
->entries
[tc_idx
] = e
;
2922 ++(tcache
->counts
[tc_idx
]);
2925 /* Caller must ensure that we know tc_idx is valid and there's
2926 available chunks to remove. */
2927 static __always_inline
void *
2928 tcache_get (size_t tc_idx
)
2930 tcache_entry
*e
= tcache
->entries
[tc_idx
];
2931 assert (tc_idx
< TCACHE_MAX_BINS
);
2932 assert (tcache
->entries
[tc_idx
] > 0);
2933 tcache
->entries
[tc_idx
] = e
->next
;
2934 --(tcache
->counts
[tc_idx
]);
2938 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
2939 tcache_thread_freeres (void)
2942 tcache_perthread_struct
*tcache_tmp
= tcache
;
2947 /* Disable the tcache and prevent it from being reinitialized. */
2949 tcache_shutting_down
= true;
2951 /* Free all of the entries and the tcache itself back to the arena
2952 heap for coalescing. */
2953 for (i
= 0; i
< TCACHE_MAX_BINS
; ++i
)
2955 while (tcache_tmp
->entries
[i
])
2957 tcache_entry
*e
= tcache_tmp
->entries
[i
];
2958 tcache_tmp
->entries
[i
] = e
->next
;
2963 __libc_free (tcache_tmp
);
2965 text_set_element (__libc_thread_subfreeres
, tcache_thread_freeres
);
2972 const size_t bytes
= sizeof (tcache_perthread_struct
);
2974 if (tcache_shutting_down
)
2977 arena_get (ar_ptr
, bytes
);
2978 victim
= _int_malloc (ar_ptr
, bytes
);
2979 if (!victim
&& ar_ptr
!= NULL
)
2981 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
2982 victim
= _int_malloc (ar_ptr
, bytes
);
2987 __libc_lock_unlock (ar_ptr
->mutex
);
2989 /* In a low memory situation, we may not be able to allocate memory
2990 - in which case, we just keep trying later. However, we
2991 typically do this very early, so either there is sufficient
2992 memory, or there isn't enough memory to do non-trivial
2993 allocations anyway. */
2996 tcache
= (tcache_perthread_struct
*) victim
;
2997 memset (tcache
, 0, sizeof (tcache_perthread_struct
));
3002 #define MAYBE_INIT_TCACHE() \
3003 if (__glibc_unlikely (tcache == NULL)) \
3007 #define MAYBE_INIT_TCACHE()
3011 __libc_malloc (size_t bytes
)
3016 void *(*hook
) (size_t, const void *)
3017 = atomic_forced_read (__malloc_hook
);
3018 if (__builtin_expect (hook
!= NULL
, 0))
3019 return (*hook
)(bytes
, RETURN_ADDRESS (0));
3021 /* int_free also calls request2size, be careful to not pad twice. */
3022 size_t tbytes
= request2size (bytes
);
3023 size_t tc_idx
= csize2tidx (tbytes
);
3025 MAYBE_INIT_TCACHE ();
3027 DIAG_PUSH_NEEDS_COMMENT
;
3028 if (tc_idx
< mp_
.tcache_bins
3029 /*&& tc_idx < TCACHE_MAX_BINS*/ /* to appease gcc */
3031 && tcache
->entries
[tc_idx
] != NULL
)
3033 return tcache_get (tc_idx
);
3035 DIAG_POP_NEEDS_COMMENT
;
3038 arena_get (ar_ptr
, bytes
);
3040 victim
= _int_malloc (ar_ptr
, bytes
);
3041 /* Retry with another arena only if we were able to find a usable arena
3043 if (!victim
&& ar_ptr
!= NULL
)
3045 LIBC_PROBE (memory_malloc_retry
, 1, bytes
);
3046 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
3047 victim
= _int_malloc (ar_ptr
, bytes
);
3051 __libc_lock_unlock (ar_ptr
->mutex
);
3053 assert (!victim
|| chunk_is_mmapped (mem2chunk (victim
)) ||
3054 ar_ptr
== arena_for_chunk (mem2chunk (victim
)));
3057 libc_hidden_def (__libc_malloc
)
3060 __libc_free (void *mem
)
3063 mchunkptr p
; /* chunk corresponding to mem */
3065 void (*hook
) (void *, const void *)
3066 = atomic_forced_read (__free_hook
);
3067 if (__builtin_expect (hook
!= NULL
, 0))
3069 (*hook
)(mem
, RETURN_ADDRESS (0));
3073 if (mem
== 0) /* free(0) has no effect */
3076 p
= mem2chunk (mem
);
3078 if (chunk_is_mmapped (p
)) /* release mmapped memory. */
3080 /* See if the dynamic brk/mmap threshold needs adjusting.
3081 Dumped fake mmapped chunks do not affect the threshold. */
3082 if (!mp_
.no_dyn_threshold
3083 && chunksize_nomask (p
) > mp_
.mmap_threshold
3084 && chunksize_nomask (p
) <= DEFAULT_MMAP_THRESHOLD_MAX
3085 && !DUMPED_MAIN_ARENA_CHUNK (p
))
3087 mp_
.mmap_threshold
= chunksize (p
);
3088 mp_
.trim_threshold
= 2 * mp_
.mmap_threshold
;
3089 LIBC_PROBE (memory_mallopt_free_dyn_thresholds
, 2,
3090 mp_
.mmap_threshold
, mp_
.trim_threshold
);
3096 MAYBE_INIT_TCACHE ();
3098 ar_ptr
= arena_for_chunk (p
);
3099 _int_free (ar_ptr
, p
, 0);
3101 libc_hidden_def (__libc_free
)
3104 __libc_realloc (void *oldmem
, size_t bytes
)
3107 INTERNAL_SIZE_T nb
; /* padded request size */
3109 void *newp
; /* chunk to return */
3111 void *(*hook
) (void *, size_t, const void *) =
3112 atomic_forced_read (__realloc_hook
);
3113 if (__builtin_expect (hook
!= NULL
, 0))
3114 return (*hook
)(oldmem
, bytes
, RETURN_ADDRESS (0));
3116 #if REALLOC_ZERO_BYTES_FREES
3117 if (bytes
== 0 && oldmem
!= NULL
)
3119 __libc_free (oldmem
); return 0;
3123 /* realloc of null is supposed to be same as malloc */
3125 return __libc_malloc (bytes
);
3127 /* chunk corresponding to oldmem */
3128 const mchunkptr oldp
= mem2chunk (oldmem
);
3130 const INTERNAL_SIZE_T oldsize
= chunksize (oldp
);
3132 if (chunk_is_mmapped (oldp
))
3136 MAYBE_INIT_TCACHE ();
3137 ar_ptr
= arena_for_chunk (oldp
);
3140 /* Little security check which won't hurt performance: the allocator
3141 never wrapps around at the end of the address space. Therefore
3142 we can exclude some size values which might appear here by
3143 accident or by "design" from some intruder. We need to bypass
3144 this check for dumped fake mmap chunks from the old main arena
3145 because the new malloc may provide additional alignment. */
3146 if ((__builtin_expect ((uintptr_t) oldp
> (uintptr_t) -oldsize
, 0)
3147 || __builtin_expect (misaligned_chunk (oldp
), 0))
3148 && !DUMPED_MAIN_ARENA_CHUNK (oldp
))
3149 malloc_printerr ("realloc(): invalid pointer");
3151 checked_request2size (bytes
, nb
);
3153 if (chunk_is_mmapped (oldp
))
3155 /* If this is a faked mmapped chunk from the dumped main arena,
3156 always make a copy (and do not free the old chunk). */
3157 if (DUMPED_MAIN_ARENA_CHUNK (oldp
))
3159 /* Must alloc, copy, free. */
3160 void *newmem
= __libc_malloc (bytes
);
3163 /* Copy as many bytes as are available from the old chunk
3164 and fit into the new size. NB: The overhead for faked
3165 mmapped chunks is only SIZE_SZ, not 2 * SIZE_SZ as for
3166 regular mmapped chunks. */
3167 if (bytes
> oldsize
- SIZE_SZ
)
3168 bytes
= oldsize
- SIZE_SZ
;
3169 memcpy (newmem
, oldmem
, bytes
);
3176 newp
= mremap_chunk (oldp
, nb
);
3178 return chunk2mem (newp
);
3180 /* Note the extra SIZE_SZ overhead. */
3181 if (oldsize
- SIZE_SZ
>= nb
)
3182 return oldmem
; /* do nothing */
3184 /* Must alloc, copy, free. */
3185 newmem
= __libc_malloc (bytes
);
3187 return 0; /* propagate failure */
3189 memcpy (newmem
, oldmem
, oldsize
- 2 * SIZE_SZ
);
3190 munmap_chunk (oldp
);
3194 __libc_lock_lock (ar_ptr
->mutex
);
3196 newp
= _int_realloc (ar_ptr
, oldp
, oldsize
, nb
);
3198 __libc_lock_unlock (ar_ptr
->mutex
);
3199 assert (!newp
|| chunk_is_mmapped (mem2chunk (newp
)) ||
3200 ar_ptr
== arena_for_chunk (mem2chunk (newp
)));
3204 /* Try harder to allocate memory in other arenas. */
3205 LIBC_PROBE (memory_realloc_retry
, 2, bytes
, oldmem
);
3206 newp
= __libc_malloc (bytes
);
3209 memcpy (newp
, oldmem
, oldsize
- SIZE_SZ
);
3210 _int_free (ar_ptr
, oldp
, 0);
3216 libc_hidden_def (__libc_realloc
)
3219 __libc_memalign (size_t alignment
, size_t bytes
)
3221 void *address
= RETURN_ADDRESS (0);
3222 return _mid_memalign (alignment
, bytes
, address
);
3226 _mid_memalign (size_t alignment
, size_t bytes
, void *address
)
3231 void *(*hook
) (size_t, size_t, const void *) =
3232 atomic_forced_read (__memalign_hook
);
3233 if (__builtin_expect (hook
!= NULL
, 0))
3234 return (*hook
)(alignment
, bytes
, address
);
3236 /* If we need less alignment than we give anyway, just relay to malloc. */
3237 if (alignment
<= MALLOC_ALIGNMENT
)
3238 return __libc_malloc (bytes
);
3240 /* Otherwise, ensure that it is at least a minimum chunk size */
3241 if (alignment
< MINSIZE
)
3242 alignment
= MINSIZE
;
3244 /* If the alignment is greater than SIZE_MAX / 2 + 1 it cannot be a
3245 power of 2 and will cause overflow in the check below. */
3246 if (alignment
> SIZE_MAX
/ 2 + 1)
3248 __set_errno (EINVAL
);
3252 /* Check for overflow. */
3253 if (bytes
> SIZE_MAX
- alignment
- MINSIZE
)
3255 __set_errno (ENOMEM
);
3260 /* Make sure alignment is power of 2. */
3261 if (!powerof2 (alignment
))
3263 size_t a
= MALLOC_ALIGNMENT
* 2;
3264 while (a
< alignment
)
3269 arena_get (ar_ptr
, bytes
+ alignment
+ MINSIZE
);
3271 p
= _int_memalign (ar_ptr
, alignment
, bytes
);
3272 if (!p
&& ar_ptr
!= NULL
)
3274 LIBC_PROBE (memory_memalign_retry
, 2, bytes
, alignment
);
3275 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
3276 p
= _int_memalign (ar_ptr
, alignment
, bytes
);
3280 __libc_lock_unlock (ar_ptr
->mutex
);
3282 assert (!p
|| chunk_is_mmapped (mem2chunk (p
)) ||
3283 ar_ptr
== arena_for_chunk (mem2chunk (p
)));
3287 weak_alias (__libc_memalign
, aligned_alloc
)
3288 libc_hidden_def (__libc_memalign
)
3291 __libc_valloc (size_t bytes
)
3293 if (__malloc_initialized
< 0)
3296 void *address
= RETURN_ADDRESS (0);
3297 size_t pagesize
= GLRO (dl_pagesize
);
3298 return _mid_memalign (pagesize
, bytes
, address
);
3302 __libc_pvalloc (size_t bytes
)
3304 if (__malloc_initialized
< 0)
3307 void *address
= RETURN_ADDRESS (0);
3308 size_t pagesize
= GLRO (dl_pagesize
);
3309 size_t rounded_bytes
= ALIGN_UP (bytes
, pagesize
);
3311 /* Check for overflow. */
3312 if (bytes
> SIZE_MAX
- 2 * pagesize
- MINSIZE
)
3314 __set_errno (ENOMEM
);
3318 return _mid_memalign (pagesize
, rounded_bytes
, address
);
3322 __libc_calloc (size_t n
, size_t elem_size
)
3325 mchunkptr oldtop
, p
;
3326 INTERNAL_SIZE_T bytes
, sz
, csz
, oldtopsize
;
3328 unsigned long clearsize
;
3329 unsigned long nclears
;
3332 /* size_t is unsigned so the behavior on overflow is defined. */
3333 bytes
= n
* elem_size
;
3334 #define HALF_INTERNAL_SIZE_T \
3335 (((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2))
3336 if (__builtin_expect ((n
| elem_size
) >= HALF_INTERNAL_SIZE_T
, 0))
3338 if (elem_size
!= 0 && bytes
/ elem_size
!= n
)
3340 __set_errno (ENOMEM
);
3345 void *(*hook
) (size_t, const void *) =
3346 atomic_forced_read (__malloc_hook
);
3347 if (__builtin_expect (hook
!= NULL
, 0))
3350 mem
= (*hook
)(sz
, RETURN_ADDRESS (0));
3354 return memset (mem
, 0, sz
);
3359 MAYBE_INIT_TCACHE ();
3364 /* Check if we hand out the top chunk, in which case there may be no
3368 oldtopsize
= chunksize (top (av
));
3369 # if MORECORE_CLEARS < 2
3370 /* Only newly allocated memory is guaranteed to be cleared. */
3371 if (av
== &main_arena
&&
3372 oldtopsize
< mp_
.sbrk_base
+ av
->max_system_mem
- (char *) oldtop
)
3373 oldtopsize
= (mp_
.sbrk_base
+ av
->max_system_mem
- (char *) oldtop
);
3375 if (av
!= &main_arena
)
3377 heap_info
*heap
= heap_for_ptr (oldtop
);
3378 if (oldtopsize
< (char *) heap
+ heap
->mprotect_size
- (char *) oldtop
)
3379 oldtopsize
= (char *) heap
+ heap
->mprotect_size
- (char *) oldtop
;
3385 /* No usable arenas. */
3389 mem
= _int_malloc (av
, sz
);
3392 assert (!mem
|| chunk_is_mmapped (mem2chunk (mem
)) ||
3393 av
== arena_for_chunk (mem2chunk (mem
)));
3395 if (mem
== 0 && av
!= NULL
)
3397 LIBC_PROBE (memory_calloc_retry
, 1, sz
);
3398 av
= arena_get_retry (av
, sz
);
3399 mem
= _int_malloc (av
, sz
);
3403 __libc_lock_unlock (av
->mutex
);
3405 /* Allocation failed even after a retry. */
3409 p
= mem2chunk (mem
);
3411 /* Two optional cases in which clearing not necessary */
3412 if (chunk_is_mmapped (p
))
3414 if (__builtin_expect (perturb_byte
, 0))
3415 return memset (mem
, 0, sz
);
3420 csz
= chunksize (p
);
3423 if (perturb_byte
== 0 && (p
== oldtop
&& csz
> oldtopsize
))
3425 /* clear only the bytes from non-freshly-sbrked memory */
3430 /* Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that
3431 contents have an odd number of INTERNAL_SIZE_T-sized words;
3433 d
= (INTERNAL_SIZE_T
*) mem
;
3434 clearsize
= csz
- SIZE_SZ
;
3435 nclears
= clearsize
/ sizeof (INTERNAL_SIZE_T
);
3436 assert (nclears
>= 3);
3439 return memset (d
, 0, clearsize
);
3467 ------------------------------ malloc ------------------------------
3471 _int_malloc (mstate av
, size_t bytes
)
3473 INTERNAL_SIZE_T nb
; /* normalized request size */
3474 unsigned int idx
; /* associated bin index */
3475 mbinptr bin
; /* associated bin */
3477 mchunkptr victim
; /* inspected/selected chunk */
3478 INTERNAL_SIZE_T size
; /* its size */
3479 int victim_index
; /* its bin index */
3481 mchunkptr remainder
; /* remainder from a split */
3482 unsigned long remainder_size
; /* its size */
3484 unsigned int block
; /* bit map traverser */
3485 unsigned int bit
; /* bit map traverser */
3486 unsigned int map
; /* current word of binmap */
3488 mchunkptr fwd
; /* misc temp for linking */
3489 mchunkptr bck
; /* misc temp for linking */
3492 size_t tcache_unsorted_count
; /* count of unsorted chunks processed */
3496 Convert request size to internal form by adding SIZE_SZ bytes
3497 overhead plus possibly more to obtain necessary alignment and/or
3498 to obtain a size of at least MINSIZE, the smallest allocatable
3499 size. Also, checked_request2size traps (returning 0) request sizes
3500 that are so large that they wrap around zero when padded and
3504 checked_request2size (bytes
, nb
);
3506 /* There are no usable arenas. Fall back to sysmalloc to get a chunk from
3508 if (__glibc_unlikely (av
== NULL
))
3510 void *p
= sysmalloc (nb
, av
);
3512 alloc_perturb (p
, bytes
);
3517 If the size qualifies as a fastbin, first check corresponding bin.
3518 This code is safe to execute even if av is not yet initialized, so we
3519 can try it without checking, which saves some time on this fast path.
3522 #define REMOVE_FB(fb, victim, pp) \
3526 if (victim == NULL) \
3529 while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) \
3532 if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ()))
3534 idx
= fastbin_index (nb
);
3535 mfastbinptr
*fb
= &fastbin (av
, idx
);
3537 REMOVE_FB (fb
, victim
, pp
);
3540 if (__builtin_expect (fastbin_index (chunksize (victim
)) != idx
, 0))
3541 malloc_printerr ("malloc(): memory corruption (fast)");
3542 check_remalloced_chunk (av
, victim
, nb
);
3544 /* While we're here, if we see other chunks of the same size,
3545 stash them in the tcache. */
3546 size_t tc_idx
= csize2tidx (nb
);
3547 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3549 mchunkptr tc_victim
;
3551 /* While bin not empty and tcache not full, copy chunks over. */
3552 while (tcache
->counts
[tc_idx
] < mp_
.tcache_count
3553 && (pp
= *fb
) != NULL
)
3555 REMOVE_FB (fb
, tc_victim
, pp
);
3558 tcache_put (tc_victim
, tc_idx
);
3563 void *p
= chunk2mem (victim
);
3564 alloc_perturb (p
, bytes
);
3570 If a small request, check regular bin. Since these "smallbins"
3571 hold one size each, no searching within bins is necessary.
3572 (For a large request, we need to wait until unsorted chunks are
3573 processed to find best fit. But for small ones, fits are exact
3574 anyway, so we can check now, which is faster.)
3577 if (in_smallbin_range (nb
))
3579 idx
= smallbin_index (nb
);
3580 bin
= bin_at (av
, idx
);
3582 if ((victim
= last (bin
)) != bin
)
3585 if (__glibc_unlikely (bck
->fd
!= victim
))
3586 malloc_printerr ("malloc(): smallbin double linked list corrupted");
3587 set_inuse_bit_at_offset (victim
, nb
);
3591 if (av
!= &main_arena
)
3592 set_non_main_arena (victim
);
3593 check_malloced_chunk (av
, victim
, nb
);
3595 /* While we're here, if we see other chunks of the same size,
3596 stash them in the tcache. */
3597 size_t tc_idx
= csize2tidx (nb
);
3598 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3600 mchunkptr tc_victim
;
3602 /* While bin not empty and tcache not full, copy chunks over. */
3603 while (tcache
->counts
[tc_idx
] < mp_
.tcache_count
3604 && (tc_victim
= last (bin
)) != bin
)
3608 bck
= tc_victim
->bk
;
3609 set_inuse_bit_at_offset (tc_victim
, nb
);
3610 if (av
!= &main_arena
)
3611 set_non_main_arena (tc_victim
);
3615 tcache_put (tc_victim
, tc_idx
);
3620 void *p
= chunk2mem (victim
);
3621 alloc_perturb (p
, bytes
);
3627 If this is a large request, consolidate fastbins before continuing.
3628 While it might look excessive to kill all fastbins before
3629 even seeing if there is space available, this avoids
3630 fragmentation problems normally associated with fastbins.
3631 Also, in practice, programs tend to have runs of either small or
3632 large requests, but less often mixtures, so consolidation is not
3633 invoked all that often in most programs. And the programs that
3634 it is called frequently in otherwise tend to fragment.
3639 idx
= largebin_index (nb
);
3640 if (atomic_load_relaxed (&av
->have_fastchunks
))
3641 malloc_consolidate (av
);
3645 Process recently freed or remaindered chunks, taking one only if
3646 it is exact fit, or, if this a small request, the chunk is remainder from
3647 the most recent non-exact fit. Place other traversed chunks in
3648 bins. Note that this step is the only place in any routine where
3649 chunks are placed in bins.
3651 The outer loop here is needed because we might not realize until
3652 near the end of malloc that we should have consolidated, so must
3653 do so and retry. This happens at most once, and only when we would
3654 otherwise need to expand memory to service a "small" request.
3658 INTERNAL_SIZE_T tcache_nb
= 0;
3659 size_t tc_idx
= csize2tidx (nb
);
3660 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3662 int return_cached
= 0;
3664 tcache_unsorted_count
= 0;
3670 while ((victim
= unsorted_chunks (av
)->bk
) != unsorted_chunks (av
))
3673 if (__builtin_expect (chunksize_nomask (victim
) <= 2 * SIZE_SZ
, 0)
3674 || __builtin_expect (chunksize_nomask (victim
)
3675 > av
->system_mem
, 0))
3676 malloc_printerr ("malloc(): memory corruption");
3677 size
= chunksize (victim
);
3680 If a small request, try to use last remainder if it is the
3681 only chunk in unsorted bin. This helps promote locality for
3682 runs of consecutive small requests. This is the only
3683 exception to best-fit, and applies only when there is
3684 no exact fit for a small chunk.
3687 if (in_smallbin_range (nb
) &&
3688 bck
== unsorted_chunks (av
) &&
3689 victim
== av
->last_remainder
&&
3690 (unsigned long) (size
) > (unsigned long) (nb
+ MINSIZE
))
3692 /* split and reattach remainder */
3693 remainder_size
= size
- nb
;
3694 remainder
= chunk_at_offset (victim
, nb
);
3695 unsorted_chunks (av
)->bk
= unsorted_chunks (av
)->fd
= remainder
;
3696 av
->last_remainder
= remainder
;
3697 remainder
->bk
= remainder
->fd
= unsorted_chunks (av
);
3698 if (!in_smallbin_range (remainder_size
))
3700 remainder
->fd_nextsize
= NULL
;
3701 remainder
->bk_nextsize
= NULL
;
3704 set_head (victim
, nb
| PREV_INUSE
|
3705 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
3706 set_head (remainder
, remainder_size
| PREV_INUSE
);
3707 set_foot (remainder
, remainder_size
);
3709 check_malloced_chunk (av
, victim
, nb
);
3710 void *p
= chunk2mem (victim
);
3711 alloc_perturb (p
, bytes
);
3715 /* remove from unsorted list */
3716 unsorted_chunks (av
)->bk
= bck
;
3717 bck
->fd
= unsorted_chunks (av
);
3719 /* Take now instead of binning if exact fit */
3723 set_inuse_bit_at_offset (victim
, size
);
3724 if (av
!= &main_arena
)
3725 set_non_main_arena (victim
);
3727 /* Fill cache first, return to user only if cache fills.
3728 We may return one of these chunks later. */
3730 && tcache
->counts
[tc_idx
] < mp_
.tcache_count
)
3732 tcache_put (victim
, tc_idx
);
3739 check_malloced_chunk (av
, victim
, nb
);
3740 void *p
= chunk2mem (victim
);
3741 alloc_perturb (p
, bytes
);
3748 /* place chunk in bin */
3750 if (in_smallbin_range (size
))
3752 victim_index
= smallbin_index (size
);
3753 bck
= bin_at (av
, victim_index
);
3758 victim_index
= largebin_index (size
);
3759 bck
= bin_at (av
, victim_index
);
3762 /* maintain large bins in sorted order */
3765 /* Or with inuse bit to speed comparisons */
3767 /* if smaller than smallest, bypass loop below */
3768 assert (chunk_main_arena (bck
->bk
));
3769 if ((unsigned long) (size
)
3770 < (unsigned long) chunksize_nomask (bck
->bk
))
3775 victim
->fd_nextsize
= fwd
->fd
;
3776 victim
->bk_nextsize
= fwd
->fd
->bk_nextsize
;
3777 fwd
->fd
->bk_nextsize
= victim
->bk_nextsize
->fd_nextsize
= victim
;
3781 assert (chunk_main_arena (fwd
));
3782 while ((unsigned long) size
< chunksize_nomask (fwd
))
3784 fwd
= fwd
->fd_nextsize
;
3785 assert (chunk_main_arena (fwd
));
3788 if ((unsigned long) size
3789 == (unsigned long) chunksize_nomask (fwd
))
3790 /* Always insert in the second position. */
3794 victim
->fd_nextsize
= fwd
;
3795 victim
->bk_nextsize
= fwd
->bk_nextsize
;
3796 fwd
->bk_nextsize
= victim
;
3797 victim
->bk_nextsize
->fd_nextsize
= victim
;
3803 victim
->fd_nextsize
= victim
->bk_nextsize
= victim
;
3806 mark_bin (av
, victim_index
);
3813 /* If we've processed as many chunks as we're allowed while
3814 filling the cache, return one of the cached ones. */
3815 ++tcache_unsorted_count
;
3817 && mp_
.tcache_unsorted_limit
> 0
3818 && tcache_unsorted_count
> mp_
.tcache_unsorted_limit
)
3820 return tcache_get (tc_idx
);
3824 #define MAX_ITERS 10000
3825 if (++iters
>= MAX_ITERS
)
3830 /* If all the small chunks we found ended up cached, return one now. */
3833 return tcache_get (tc_idx
);
3838 If a large request, scan through the chunks of current bin in
3839 sorted order to find smallest that fits. Use the skip list for this.
3842 if (!in_smallbin_range (nb
))
3844 bin
= bin_at (av
, idx
);
3846 /* skip scan if empty or largest chunk is too small */
3847 if ((victim
= first (bin
)) != bin
3848 && (unsigned long) chunksize_nomask (victim
)
3849 >= (unsigned long) (nb
))
3851 victim
= victim
->bk_nextsize
;
3852 while (((unsigned long) (size
= chunksize (victim
)) <
3853 (unsigned long) (nb
)))
3854 victim
= victim
->bk_nextsize
;
3856 /* Avoid removing the first entry for a size so that the skip
3857 list does not have to be rerouted. */
3858 if (victim
!= last (bin
)
3859 && chunksize_nomask (victim
)
3860 == chunksize_nomask (victim
->fd
))
3861 victim
= victim
->fd
;
3863 remainder_size
= size
- nb
;
3864 unlink (av
, victim
, bck
, fwd
);
3867 if (remainder_size
< MINSIZE
)
3869 set_inuse_bit_at_offset (victim
, size
);
3870 if (av
!= &main_arena
)
3871 set_non_main_arena (victim
);
3876 remainder
= chunk_at_offset (victim
, nb
);
3877 /* We cannot assume the unsorted list is empty and therefore
3878 have to perform a complete insert here. */
3879 bck
= unsorted_chunks (av
);
3881 if (__glibc_unlikely (fwd
->bk
!= bck
))
3882 malloc_printerr ("malloc(): corrupted unsorted chunks");
3883 remainder
->bk
= bck
;
3884 remainder
->fd
= fwd
;
3885 bck
->fd
= remainder
;
3886 fwd
->bk
= remainder
;
3887 if (!in_smallbin_range (remainder_size
))
3889 remainder
->fd_nextsize
= NULL
;
3890 remainder
->bk_nextsize
= NULL
;
3892 set_head (victim
, nb
| PREV_INUSE
|
3893 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
3894 set_head (remainder
, remainder_size
| PREV_INUSE
);
3895 set_foot (remainder
, remainder_size
);
3897 check_malloced_chunk (av
, victim
, nb
);
3898 void *p
= chunk2mem (victim
);
3899 alloc_perturb (p
, bytes
);
3905 Search for a chunk by scanning bins, starting with next largest
3906 bin. This search is strictly by best-fit; i.e., the smallest
3907 (with ties going to approximately the least recently used) chunk
3908 that fits is selected.
3910 The bitmap avoids needing to check that most blocks are nonempty.
3911 The particular case of skipping all bins during warm-up phases
3912 when no chunks have been returned yet is faster than it might look.
3916 bin
= bin_at (av
, idx
);
3917 block
= idx2block (idx
);
3918 map
= av
->binmap
[block
];
3919 bit
= idx2bit (idx
);
3923 /* Skip rest of block if there are no more set bits in this block. */
3924 if (bit
> map
|| bit
== 0)
3928 if (++block
>= BINMAPSIZE
) /* out of bins */
3931 while ((map
= av
->binmap
[block
]) == 0);
3933 bin
= bin_at (av
, (block
<< BINMAPSHIFT
));
3937 /* Advance to bin with set bit. There must be one. */
3938 while ((bit
& map
) == 0)
3940 bin
= next_bin (bin
);
3945 /* Inspect the bin. It is likely to be non-empty */
3946 victim
= last (bin
);
3948 /* If a false alarm (empty bin), clear the bit. */
3951 av
->binmap
[block
] = map
&= ~bit
; /* Write through */
3952 bin
= next_bin (bin
);
3958 size
= chunksize (victim
);
3960 /* We know the first chunk in this bin is big enough to use. */
3961 assert ((unsigned long) (size
) >= (unsigned long) (nb
));
3963 remainder_size
= size
- nb
;
3966 unlink (av
, victim
, bck
, fwd
);
3969 if (remainder_size
< MINSIZE
)
3971 set_inuse_bit_at_offset (victim
, size
);
3972 if (av
!= &main_arena
)
3973 set_non_main_arena (victim
);
3979 remainder
= chunk_at_offset (victim
, nb
);
3981 /* We cannot assume the unsorted list is empty and therefore
3982 have to perform a complete insert here. */
3983 bck
= unsorted_chunks (av
);
3985 if (__glibc_unlikely (fwd
->bk
!= bck
))
3986 malloc_printerr ("malloc(): corrupted unsorted chunks 2");
3987 remainder
->bk
= bck
;
3988 remainder
->fd
= fwd
;
3989 bck
->fd
= remainder
;
3990 fwd
->bk
= remainder
;
3992 /* advertise as last remainder */
3993 if (in_smallbin_range (nb
))
3994 av
->last_remainder
= remainder
;
3995 if (!in_smallbin_range (remainder_size
))
3997 remainder
->fd_nextsize
= NULL
;
3998 remainder
->bk_nextsize
= NULL
;
4000 set_head (victim
, nb
| PREV_INUSE
|
4001 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4002 set_head (remainder
, remainder_size
| PREV_INUSE
);
4003 set_foot (remainder
, remainder_size
);
4005 check_malloced_chunk (av
, victim
, nb
);
4006 void *p
= chunk2mem (victim
);
4007 alloc_perturb (p
, bytes
);
4014 If large enough, split off the chunk bordering the end of memory
4015 (held in av->top). Note that this is in accord with the best-fit
4016 search rule. In effect, av->top is treated as larger (and thus
4017 less well fitting) than any other available chunk since it can
4018 be extended to be as large as necessary (up to system
4021 We require that av->top always exists (i.e., has size >=
4022 MINSIZE) after initialization, so if it would otherwise be
4023 exhausted by current request, it is replenished. (The main
4024 reason for ensuring it exists is that we may need MINSIZE space
4025 to put in fenceposts in sysmalloc.)
4029 size
= chunksize (victim
);
4031 if ((unsigned long) (size
) >= (unsigned long) (nb
+ MINSIZE
))
4033 remainder_size
= size
- nb
;
4034 remainder
= chunk_at_offset (victim
, nb
);
4035 av
->top
= remainder
;
4036 set_head (victim
, nb
| PREV_INUSE
|
4037 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4038 set_head (remainder
, remainder_size
| PREV_INUSE
);
4040 check_malloced_chunk (av
, victim
, nb
);
4041 void *p
= chunk2mem (victim
);
4042 alloc_perturb (p
, bytes
);
4046 /* When we are using atomic ops to free fast chunks we can get
4047 here for all block sizes. */
4048 else if (atomic_load_relaxed (&av
->have_fastchunks
))
4050 malloc_consolidate (av
);
4051 /* restore original bin index */
4052 if (in_smallbin_range (nb
))
4053 idx
= smallbin_index (nb
);
4055 idx
= largebin_index (nb
);
4059 Otherwise, relay to handle system-dependent cases
4063 void *p
= sysmalloc (nb
, av
);
4065 alloc_perturb (p
, bytes
);
4072 ------------------------------ free ------------------------------
4076 _int_free (mstate av
, mchunkptr p
, int have_lock
)
4078 INTERNAL_SIZE_T size
; /* its size */
4079 mfastbinptr
*fb
; /* associated fastbin */
4080 mchunkptr nextchunk
; /* next contiguous chunk */
4081 INTERNAL_SIZE_T nextsize
; /* its size */
4082 int nextinuse
; /* true if nextchunk is used */
4083 INTERNAL_SIZE_T prevsize
; /* size of previous contiguous chunk */
4084 mchunkptr bck
; /* misc temp for linking */
4085 mchunkptr fwd
; /* misc temp for linking */
4087 size
= chunksize (p
);
4089 /* Little security check which won't hurt performance: the
4090 allocator never wrapps around at the end of the address space.
4091 Therefore we can exclude some size values which might appear
4092 here by accident or by "design" from some intruder. */
4093 if (__builtin_expect ((uintptr_t) p
> (uintptr_t) -size
, 0)
4094 || __builtin_expect (misaligned_chunk (p
), 0))
4095 malloc_printerr ("free(): invalid pointer");
4096 /* We know that each chunk is at least MINSIZE bytes in size or a
4097 multiple of MALLOC_ALIGNMENT. */
4098 if (__glibc_unlikely (size
< MINSIZE
|| !aligned_OK (size
)))
4099 malloc_printerr ("free(): invalid size");
4101 check_inuse_chunk(av
, p
);
4105 size_t tc_idx
= csize2tidx (size
);
4108 && tc_idx
< mp_
.tcache_bins
4109 && tcache
->counts
[tc_idx
] < mp_
.tcache_count
)
4111 tcache_put (p
, tc_idx
);
4118 If eligible, place chunk on a fastbin so it can be found
4119 and used quickly in malloc.
4122 if ((unsigned long)(size
) <= (unsigned long)(get_max_fast ())
4126 If TRIM_FASTBINS set, don't place chunks
4127 bordering top into fastbins
4129 && (chunk_at_offset(p
, size
) != av
->top
)
4133 if (__builtin_expect (chunksize_nomask (chunk_at_offset (p
, size
))
4135 || __builtin_expect (chunksize (chunk_at_offset (p
, size
))
4136 >= av
->system_mem
, 0))
4138 /* We might not have a lock at this point and concurrent modifications
4139 of system_mem might have let to a false positive. Redo the test
4140 after getting the lock. */
4142 || ({ __libc_lock_lock (av
->mutex
);
4143 chunksize_nomask (chunk_at_offset (p
, size
)) <= 2 * SIZE_SZ
4144 || chunksize (chunk_at_offset (p
, size
)) >= av
->system_mem
;
4146 malloc_printerr ("free(): invalid next size (fast)");
4148 __libc_lock_unlock (av
->mutex
);
4151 free_perturb (chunk2mem(p
), size
- 2 * SIZE_SZ
);
4153 atomic_store_relaxed (&av
->have_fastchunks
, true);
4154 unsigned int idx
= fastbin_index(size
);
4155 fb
= &fastbin (av
, idx
);
4157 /* Atomically link P to its fastbin: P->FD = *FB; *FB = P; */
4158 mchunkptr old
= *fb
, old2
;
4159 unsigned int old_idx
= ~0u;
4162 /* Check that the top of the bin is not the record we are going to add
4163 (i.e., double free). */
4164 if (__builtin_expect (old
== p
, 0))
4165 malloc_printerr ("double free or corruption (fasttop)");
4166 /* Check that size of fastbin chunk at the top is the same as
4167 size of the chunk that we are adding. We can dereference OLD
4168 only if we have the lock, otherwise it might have already been
4169 deallocated. See use of OLD_IDX below for the actual check. */
4170 if (have_lock
&& old
!= NULL
)
4171 old_idx
= fastbin_index(chunksize(old
));
4174 while ((old
= catomic_compare_and_exchange_val_rel (fb
, p
, old2
)) != old2
);
4176 if (have_lock
&& old
!= NULL
&& __builtin_expect (old_idx
!= idx
, 0))
4177 malloc_printerr ("invalid fastbin entry (free)");
4181 Consolidate other non-mmapped chunks as they arrive.
4184 else if (!chunk_is_mmapped(p
)) {
4186 __libc_lock_lock (av
->mutex
);
4188 nextchunk
= chunk_at_offset(p
, size
);
4190 /* Lightweight tests: check whether the block is already the
4192 if (__glibc_unlikely (p
== av
->top
))
4193 malloc_printerr ("double free or corruption (top)");
4194 /* Or whether the next chunk is beyond the boundaries of the arena. */
4195 if (__builtin_expect (contiguous (av
)
4196 && (char *) nextchunk
4197 >= ((char *) av
->top
+ chunksize(av
->top
)), 0))
4198 malloc_printerr ("double free or corruption (out)");
4199 /* Or whether the block is actually not marked used. */
4200 if (__glibc_unlikely (!prev_inuse(nextchunk
)))
4201 malloc_printerr ("double free or corruption (!prev)");
4203 nextsize
= chunksize(nextchunk
);
4204 if (__builtin_expect (chunksize_nomask (nextchunk
) <= 2 * SIZE_SZ
, 0)
4205 || __builtin_expect (nextsize
>= av
->system_mem
, 0))
4206 malloc_printerr ("free(): invalid next size (normal)");
4208 free_perturb (chunk2mem(p
), size
- 2 * SIZE_SZ
);
4210 /* consolidate backward */
4211 if (!prev_inuse(p
)) {
4212 prevsize
= prev_size (p
);
4214 p
= chunk_at_offset(p
, -((long) prevsize
));
4215 unlink(av
, p
, bck
, fwd
);
4218 if (nextchunk
!= av
->top
) {
4219 /* get and clear inuse bit */
4220 nextinuse
= inuse_bit_at_offset(nextchunk
, nextsize
);
4222 /* consolidate forward */
4224 unlink(av
, nextchunk
, bck
, fwd
);
4227 clear_inuse_bit_at_offset(nextchunk
, 0);
4230 Place the chunk in unsorted chunk list. Chunks are
4231 not placed into regular bins until after they have
4232 been given one chance to be used in malloc.
4235 bck
= unsorted_chunks(av
);
4237 if (__glibc_unlikely (fwd
->bk
!= bck
))
4238 malloc_printerr ("free(): corrupted unsorted chunks");
4241 if (!in_smallbin_range(size
))
4243 p
->fd_nextsize
= NULL
;
4244 p
->bk_nextsize
= NULL
;
4249 set_head(p
, size
| PREV_INUSE
);
4252 check_free_chunk(av
, p
);
4256 If the chunk borders the current high end of memory,
4257 consolidate into top
4262 set_head(p
, size
| PREV_INUSE
);
4268 If freeing a large space, consolidate possibly-surrounding
4269 chunks. Then, if the total unused topmost memory exceeds trim
4270 threshold, ask malloc_trim to reduce top.
4272 Unless max_fast is 0, we don't know if there are fastbins
4273 bordering top, so we cannot tell for sure whether threshold
4274 has been reached unless fastbins are consolidated. But we
4275 don't want to consolidate on each free. As a compromise,
4276 consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
4280 if ((unsigned long)(size
) >= FASTBIN_CONSOLIDATION_THRESHOLD
) {
4281 if (atomic_load_relaxed (&av
->have_fastchunks
))
4282 malloc_consolidate(av
);
4284 if (av
== &main_arena
) {
4285 #ifndef MORECORE_CANNOT_TRIM
4286 if ((unsigned long)(chunksize(av
->top
)) >=
4287 (unsigned long)(mp_
.trim_threshold
))
4288 systrim(mp_
.top_pad
, av
);
4291 /* Always try heap_trim(), even if the top chunk is not
4292 large, because the corresponding heap might go away. */
4293 heap_info
*heap
= heap_for_ptr(top(av
));
4295 assert(heap
->ar_ptr
== av
);
4296 heap_trim(heap
, mp_
.top_pad
);
4301 __libc_lock_unlock (av
->mutex
);
4304 If the chunk was allocated via mmap, release via munmap().
4313 ------------------------- malloc_consolidate -------------------------
4315 malloc_consolidate is a specialized version of free() that tears
4316 down chunks held in fastbins. Free itself cannot be used for this
4317 purpose since, among other things, it might place chunks back onto
4318 fastbins. So, instead, we need to use a minor variant of the same
4322 static void malloc_consolidate(mstate av
)
4324 mfastbinptr
* fb
; /* current fastbin being consolidated */
4325 mfastbinptr
* maxfb
; /* last fastbin (for loop control) */
4326 mchunkptr p
; /* current chunk being consolidated */
4327 mchunkptr nextp
; /* next chunk to consolidate */
4328 mchunkptr unsorted_bin
; /* bin header */
4329 mchunkptr first_unsorted
; /* chunk to link to */
4331 /* These have same use as in free() */
4332 mchunkptr nextchunk
;
4333 INTERNAL_SIZE_T size
;
4334 INTERNAL_SIZE_T nextsize
;
4335 INTERNAL_SIZE_T prevsize
;
4340 atomic_store_relaxed (&av
->have_fastchunks
, false);
4342 unsorted_bin
= unsorted_chunks(av
);
4345 Remove each chunk from fast bin and consolidate it, placing it
4346 then in unsorted bin. Among other reasons for doing this,
4347 placing in unsorted bin avoids needing to calculate actual bins
4348 until malloc is sure that chunks aren't immediately going to be
4352 maxfb
= &fastbin (av
, NFASTBINS
- 1);
4353 fb
= &fastbin (av
, 0);
4355 p
= atomic_exchange_acq (fb
, NULL
);
4358 check_inuse_chunk(av
, p
);
4361 /* Slightly streamlined version of consolidation code in free() */
4362 size
= chunksize (p
);
4363 nextchunk
= chunk_at_offset(p
, size
);
4364 nextsize
= chunksize(nextchunk
);
4366 if (!prev_inuse(p
)) {
4367 prevsize
= prev_size (p
);
4369 p
= chunk_at_offset(p
, -((long) prevsize
));
4370 unlink(av
, p
, bck
, fwd
);
4373 if (nextchunk
!= av
->top
) {
4374 nextinuse
= inuse_bit_at_offset(nextchunk
, nextsize
);
4378 unlink(av
, nextchunk
, bck
, fwd
);
4380 clear_inuse_bit_at_offset(nextchunk
, 0);
4382 first_unsorted
= unsorted_bin
->fd
;
4383 unsorted_bin
->fd
= p
;
4384 first_unsorted
->bk
= p
;
4386 if (!in_smallbin_range (size
)) {
4387 p
->fd_nextsize
= NULL
;
4388 p
->bk_nextsize
= NULL
;
4391 set_head(p
, size
| PREV_INUSE
);
4392 p
->bk
= unsorted_bin
;
4393 p
->fd
= first_unsorted
;
4399 set_head(p
, size
| PREV_INUSE
);
4403 } while ( (p
= nextp
) != 0);
4406 } while (fb
++ != maxfb
);
4410 ------------------------------ realloc ------------------------------
4414 _int_realloc(mstate av
, mchunkptr oldp
, INTERNAL_SIZE_T oldsize
,
4417 mchunkptr newp
; /* chunk to return */
4418 INTERNAL_SIZE_T newsize
; /* its size */
4419 void* newmem
; /* corresponding user mem */
4421 mchunkptr next
; /* next contiguous chunk after oldp */
4423 mchunkptr remainder
; /* extra space at end of newp */
4424 unsigned long remainder_size
; /* its size */
4426 mchunkptr bck
; /* misc temp for linking */
4427 mchunkptr fwd
; /* misc temp for linking */
4429 unsigned long copysize
; /* bytes to copy */
4430 unsigned int ncopies
; /* INTERNAL_SIZE_T words to copy */
4431 INTERNAL_SIZE_T
* s
; /* copy source */
4432 INTERNAL_SIZE_T
* d
; /* copy destination */
4435 if (__builtin_expect (chunksize_nomask (oldp
) <= 2 * SIZE_SZ
, 0)
4436 || __builtin_expect (oldsize
>= av
->system_mem
, 0))
4437 malloc_printerr ("realloc(): invalid old size");
4439 check_inuse_chunk (av
, oldp
);
4441 /* All callers already filter out mmap'ed chunks. */
4442 assert (!chunk_is_mmapped (oldp
));
4444 next
= chunk_at_offset (oldp
, oldsize
);
4445 INTERNAL_SIZE_T nextsize
= chunksize (next
);
4446 if (__builtin_expect (chunksize_nomask (next
) <= 2 * SIZE_SZ
, 0)
4447 || __builtin_expect (nextsize
>= av
->system_mem
, 0))
4448 malloc_printerr ("realloc(): invalid next size");
4450 if ((unsigned long) (oldsize
) >= (unsigned long) (nb
))
4452 /* already big enough; split below */
4459 /* Try to expand forward into top */
4460 if (next
== av
->top
&&
4461 (unsigned long) (newsize
= oldsize
+ nextsize
) >=
4462 (unsigned long) (nb
+ MINSIZE
))
4464 set_head_size (oldp
, nb
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4465 av
->top
= chunk_at_offset (oldp
, nb
);
4466 set_head (av
->top
, (newsize
- nb
) | PREV_INUSE
);
4467 check_inuse_chunk (av
, oldp
);
4468 return chunk2mem (oldp
);
4471 /* Try to expand forward into next chunk; split off remainder below */
4472 else if (next
!= av
->top
&&
4474 (unsigned long) (newsize
= oldsize
+ nextsize
) >=
4475 (unsigned long) (nb
))
4478 unlink (av
, next
, bck
, fwd
);
4481 /* allocate, copy, free */
4484 newmem
= _int_malloc (av
, nb
- MALLOC_ALIGN_MASK
);
4486 return 0; /* propagate failure */
4488 newp
= mem2chunk (newmem
);
4489 newsize
= chunksize (newp
);
4492 Avoid copy if newp is next chunk after oldp.
4502 Unroll copy of <= 36 bytes (72 if 8byte sizes)
4503 We know that contents have an odd number of
4504 INTERNAL_SIZE_T-sized words; minimally 3.
4507 copysize
= oldsize
- SIZE_SZ
;
4508 s
= (INTERNAL_SIZE_T
*) (chunk2mem (oldp
));
4509 d
= (INTERNAL_SIZE_T
*) (newmem
);
4510 ncopies
= copysize
/ sizeof (INTERNAL_SIZE_T
);
4511 assert (ncopies
>= 3);
4514 memcpy (d
, s
, copysize
);
4518 *(d
+ 0) = *(s
+ 0);
4519 *(d
+ 1) = *(s
+ 1);
4520 *(d
+ 2) = *(s
+ 2);
4523 *(d
+ 3) = *(s
+ 3);
4524 *(d
+ 4) = *(s
+ 4);
4527 *(d
+ 5) = *(s
+ 5);
4528 *(d
+ 6) = *(s
+ 6);
4531 *(d
+ 7) = *(s
+ 7);
4532 *(d
+ 8) = *(s
+ 8);
4538 _int_free (av
, oldp
, 1);
4539 check_inuse_chunk (av
, newp
);
4540 return chunk2mem (newp
);
4545 /* If possible, free extra space in old or extended chunk */
4547 assert ((unsigned long) (newsize
) >= (unsigned long) (nb
));
4549 remainder_size
= newsize
- nb
;
4551 if (remainder_size
< MINSIZE
) /* not enough extra to split off */
4553 set_head_size (newp
, newsize
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4554 set_inuse_bit_at_offset (newp
, newsize
);
4556 else /* split remainder */
4558 remainder
= chunk_at_offset (newp
, nb
);
4559 set_head_size (newp
, nb
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4560 set_head (remainder
, remainder_size
| PREV_INUSE
|
4561 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4562 /* Mark remainder as inuse so free() won't complain */
4563 set_inuse_bit_at_offset (remainder
, remainder_size
);
4564 _int_free (av
, remainder
, 1);
4567 check_inuse_chunk (av
, newp
);
4568 return chunk2mem (newp
);
4572 ------------------------------ memalign ------------------------------
4576 _int_memalign (mstate av
, size_t alignment
, size_t bytes
)
4578 INTERNAL_SIZE_T nb
; /* padded request size */
4579 char *m
; /* memory returned by malloc call */
4580 mchunkptr p
; /* corresponding chunk */
4581 char *brk
; /* alignment point within p */
4582 mchunkptr newp
; /* chunk to return */
4583 INTERNAL_SIZE_T newsize
; /* its size */
4584 INTERNAL_SIZE_T leadsize
; /* leading space before alignment point */
4585 mchunkptr remainder
; /* spare room at end to split off */
4586 unsigned long remainder_size
; /* its size */
4587 INTERNAL_SIZE_T size
;
4591 checked_request2size (bytes
, nb
);
4594 Strategy: find a spot within that chunk that meets the alignment
4595 request, and then possibly free the leading and trailing space.
4599 /* Call malloc with worst case padding to hit alignment. */
4601 m
= (char *) (_int_malloc (av
, nb
+ alignment
+ MINSIZE
));
4604 return 0; /* propagate failure */
4608 if ((((unsigned long) (m
)) % alignment
) != 0) /* misaligned */
4611 Find an aligned spot inside chunk. Since we need to give back
4612 leading space in a chunk of at least MINSIZE, if the first
4613 calculation places us at a spot with less than MINSIZE leader,
4614 we can move to the next aligned spot -- we've allocated enough
4615 total room so that this is always possible.
4617 brk
= (char *) mem2chunk (((unsigned long) (m
+ alignment
- 1)) &
4618 - ((signed long) alignment
));
4619 if ((unsigned long) (brk
- (char *) (p
)) < MINSIZE
)
4622 newp
= (mchunkptr
) brk
;
4623 leadsize
= brk
- (char *) (p
);
4624 newsize
= chunksize (p
) - leadsize
;
4626 /* For mmapped chunks, just adjust offset */
4627 if (chunk_is_mmapped (p
))
4629 set_prev_size (newp
, prev_size (p
) + leadsize
);
4630 set_head (newp
, newsize
| IS_MMAPPED
);
4631 return chunk2mem (newp
);
4634 /* Otherwise, give back leader, use the rest */
4635 set_head (newp
, newsize
| PREV_INUSE
|
4636 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4637 set_inuse_bit_at_offset (newp
, newsize
);
4638 set_head_size (p
, leadsize
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4639 _int_free (av
, p
, 1);
4642 assert (newsize
>= nb
&&
4643 (((unsigned long) (chunk2mem (p
))) % alignment
) == 0);
4646 /* Also give back spare room at the end */
4647 if (!chunk_is_mmapped (p
))
4649 size
= chunksize (p
);
4650 if ((unsigned long) (size
) > (unsigned long) (nb
+ MINSIZE
))
4652 remainder_size
= size
- nb
;
4653 remainder
= chunk_at_offset (p
, nb
);
4654 set_head (remainder
, remainder_size
| PREV_INUSE
|
4655 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4656 set_head_size (p
, nb
);
4657 _int_free (av
, remainder
, 1);
4661 check_inuse_chunk (av
, p
);
4662 return chunk2mem (p
);
4667 ------------------------------ malloc_trim ------------------------------
4671 mtrim (mstate av
, size_t pad
)
4673 /* Ensure all blocks are consolidated. */
4674 malloc_consolidate (av
);
4676 const size_t ps
= GLRO (dl_pagesize
);
4677 int psindex
= bin_index (ps
);
4678 const size_t psm1
= ps
- 1;
4681 for (int i
= 1; i
< NBINS
; ++i
)
4682 if (i
== 1 || i
>= psindex
)
4684 mbinptr bin
= bin_at (av
, i
);
4686 for (mchunkptr p
= last (bin
); p
!= bin
; p
= p
->bk
)
4688 INTERNAL_SIZE_T size
= chunksize (p
);
4690 if (size
> psm1
+ sizeof (struct malloc_chunk
))
4692 /* See whether the chunk contains at least one unused page. */
4693 char *paligned_mem
= (char *) (((uintptr_t) p
4694 + sizeof (struct malloc_chunk
)
4697 assert ((char *) chunk2mem (p
) + 4 * SIZE_SZ
<= paligned_mem
);
4698 assert ((char *) p
+ size
> paligned_mem
);
4700 /* This is the size we could potentially free. */
4701 size
-= paligned_mem
- (char *) p
;
4706 /* When debugging we simulate destroying the memory
4708 memset (paligned_mem
, 0x89, size
& ~psm1
);
4710 __madvise (paligned_mem
, size
& ~psm1
, MADV_DONTNEED
);
4718 #ifndef MORECORE_CANNOT_TRIM
4719 return result
| (av
== &main_arena
? systrim (pad
, av
) : 0);
4728 __malloc_trim (size_t s
)
4732 if (__malloc_initialized
< 0)
4735 mstate ar_ptr
= &main_arena
;
4738 __libc_lock_lock (ar_ptr
->mutex
);
4739 result
|= mtrim (ar_ptr
, s
);
4740 __libc_lock_unlock (ar_ptr
->mutex
);
4742 ar_ptr
= ar_ptr
->next
;
4744 while (ar_ptr
!= &main_arena
);
4751 ------------------------- malloc_usable_size -------------------------
4760 p
= mem2chunk (mem
);
4762 if (__builtin_expect (using_malloc_checking
== 1, 0))
4763 return malloc_check_get_size (p
);
4765 if (chunk_is_mmapped (p
))
4767 if (DUMPED_MAIN_ARENA_CHUNK (p
))
4768 return chunksize (p
) - SIZE_SZ
;
4770 return chunksize (p
) - 2 * SIZE_SZ
;
4773 return chunksize (p
) - SIZE_SZ
;
4780 __malloc_usable_size (void *m
)
4784 result
= musable (m
);
4789 ------------------------------ mallinfo ------------------------------
4790 Accumulate malloc statistics for arena AV into M.
4794 int_mallinfo (mstate av
, struct mallinfo
*m
)
4799 INTERNAL_SIZE_T avail
;
4800 INTERNAL_SIZE_T fastavail
;
4804 check_malloc_state (av
);
4806 /* Account for top */
4807 avail
= chunksize (av
->top
);
4808 nblocks
= 1; /* top always exists */
4810 /* traverse fastbins */
4814 for (i
= 0; i
< NFASTBINS
; ++i
)
4816 for (p
= fastbin (av
, i
); p
!= 0; p
= p
->fd
)
4819 fastavail
+= chunksize (p
);
4825 /* traverse regular bins */
4826 for (i
= 1; i
< NBINS
; ++i
)
4829 for (p
= last (b
); p
!= b
; p
= p
->bk
)
4832 avail
+= chunksize (p
);
4836 m
->smblks
+= nfastblocks
;
4837 m
->ordblks
+= nblocks
;
4838 m
->fordblks
+= avail
;
4839 m
->uordblks
+= av
->system_mem
- avail
;
4840 m
->arena
+= av
->system_mem
;
4841 m
->fsmblks
+= fastavail
;
4842 if (av
== &main_arena
)
4844 m
->hblks
= mp_
.n_mmaps
;
4845 m
->hblkhd
= mp_
.mmapped_mem
;
4847 m
->keepcost
= chunksize (av
->top
);
4853 __libc_mallinfo (void)
4858 if (__malloc_initialized
< 0)
4861 memset (&m
, 0, sizeof (m
));
4862 ar_ptr
= &main_arena
;
4865 __libc_lock_lock (ar_ptr
->mutex
);
4866 int_mallinfo (ar_ptr
, &m
);
4867 __libc_lock_unlock (ar_ptr
->mutex
);
4869 ar_ptr
= ar_ptr
->next
;
4871 while (ar_ptr
!= &main_arena
);
4877 ------------------------------ malloc_stats ------------------------------
4881 __malloc_stats (void)
4885 unsigned int in_use_b
= mp_
.mmapped_mem
, system_b
= in_use_b
;
4887 if (__malloc_initialized
< 0)
4889 _IO_flockfile (stderr
);
4890 int old_flags2
= ((_IO_FILE
*) stderr
)->_flags2
;
4891 ((_IO_FILE
*) stderr
)->_flags2
|= _IO_FLAGS2_NOTCANCEL
;
4892 for (i
= 0, ar_ptr
= &main_arena
;; i
++)
4896 memset (&mi
, 0, sizeof (mi
));
4897 __libc_lock_lock (ar_ptr
->mutex
);
4898 int_mallinfo (ar_ptr
, &mi
);
4899 fprintf (stderr
, "Arena %d:\n", i
);
4900 fprintf (stderr
, "system bytes = %10u\n", (unsigned int) mi
.arena
);
4901 fprintf (stderr
, "in use bytes = %10u\n", (unsigned int) mi
.uordblks
);
4902 #if MALLOC_DEBUG > 1
4904 dump_heap (heap_for_ptr (top (ar_ptr
)));
4906 system_b
+= mi
.arena
;
4907 in_use_b
+= mi
.uordblks
;
4908 __libc_lock_unlock (ar_ptr
->mutex
);
4909 ar_ptr
= ar_ptr
->next
;
4910 if (ar_ptr
== &main_arena
)
4913 fprintf (stderr
, "Total (incl. mmap):\n");
4914 fprintf (stderr
, "system bytes = %10u\n", system_b
);
4915 fprintf (stderr
, "in use bytes = %10u\n", in_use_b
);
4916 fprintf (stderr
, "max mmap regions = %10u\n", (unsigned int) mp_
.max_n_mmaps
);
4917 fprintf (stderr
, "max mmap bytes = %10lu\n",
4918 (unsigned long) mp_
.max_mmapped_mem
);
4919 ((_IO_FILE
*) stderr
)->_flags2
|= old_flags2
;
4920 _IO_funlockfile (stderr
);
4925 ------------------------------ mallopt ------------------------------
4929 do_set_trim_threshold (size_t value
)
4931 LIBC_PROBE (memory_mallopt_trim_threshold
, 3, value
, mp_
.trim_threshold
,
4932 mp_
.no_dyn_threshold
);
4933 mp_
.trim_threshold
= value
;
4934 mp_
.no_dyn_threshold
= 1;
4940 do_set_top_pad (size_t value
)
4942 LIBC_PROBE (memory_mallopt_top_pad
, 3, value
, mp_
.top_pad
,
4943 mp_
.no_dyn_threshold
);
4944 mp_
.top_pad
= value
;
4945 mp_
.no_dyn_threshold
= 1;
4951 do_set_mmap_threshold (size_t value
)
4953 /* Forbid setting the threshold too high. */
4954 if (value
<= HEAP_MAX_SIZE
/ 2)
4956 LIBC_PROBE (memory_mallopt_mmap_threshold
, 3, value
, mp_
.mmap_threshold
,
4957 mp_
.no_dyn_threshold
);
4958 mp_
.mmap_threshold
= value
;
4959 mp_
.no_dyn_threshold
= 1;
4967 do_set_mmaps_max (int32_t value
)
4969 LIBC_PROBE (memory_mallopt_mmap_max
, 3, value
, mp_
.n_mmaps_max
,
4970 mp_
.no_dyn_threshold
);
4971 mp_
.n_mmaps_max
= value
;
4972 mp_
.no_dyn_threshold
= 1;
4978 do_set_mallopt_check (int32_t value
)
4985 do_set_perturb_byte (int32_t value
)
4987 LIBC_PROBE (memory_mallopt_perturb
, 2, value
, perturb_byte
);
4988 perturb_byte
= value
;
4994 do_set_arena_test (size_t value
)
4996 LIBC_PROBE (memory_mallopt_arena_test
, 2, value
, mp_
.arena_test
);
4997 mp_
.arena_test
= value
;
5003 do_set_arena_max (size_t value
)
5005 LIBC_PROBE (memory_mallopt_arena_max
, 2, value
, mp_
.arena_max
);
5006 mp_
.arena_max
= value
;
5013 do_set_tcache_max (size_t value
)
5015 if (value
>= 0 && value
<= MAX_TCACHE_SIZE
)
5017 LIBC_PROBE (memory_tunable_tcache_max_bytes
, 2, value
, mp_
.tcache_max_bytes
);
5018 mp_
.tcache_max_bytes
= value
;
5019 mp_
.tcache_bins
= csize2tidx (request2size(value
)) + 1;
5026 do_set_tcache_count (size_t value
)
5028 LIBC_PROBE (memory_tunable_tcache_count
, 2, value
, mp_
.tcache_count
);
5029 mp_
.tcache_count
= value
;
5035 do_set_tcache_unsorted_limit (size_t value
)
5037 LIBC_PROBE (memory_tunable_tcache_unsorted_limit
, 2, value
, mp_
.tcache_unsorted_limit
);
5038 mp_
.tcache_unsorted_limit
= value
;
5044 __libc_mallopt (int param_number
, int value
)
5046 mstate av
= &main_arena
;
5049 if (__malloc_initialized
< 0)
5051 __libc_lock_lock (av
->mutex
);
5053 LIBC_PROBE (memory_mallopt
, 2, param_number
, value
);
5055 /* We must consolidate main arena before changing max_fast
5056 (see definition of set_max_fast). */
5057 malloc_consolidate (av
);
5059 switch (param_number
)
5062 if (value
>= 0 && value
<= MAX_FAST_SIZE
)
5064 LIBC_PROBE (memory_mallopt_mxfast
, 2, value
, get_max_fast ());
5065 set_max_fast (value
);
5071 case M_TRIM_THRESHOLD
:
5072 do_set_trim_threshold (value
);
5076 do_set_top_pad (value
);
5079 case M_MMAP_THRESHOLD
:
5080 res
= do_set_mmap_threshold (value
);
5084 do_set_mmaps_max (value
);
5087 case M_CHECK_ACTION
:
5088 do_set_mallopt_check (value
);
5092 do_set_perturb_byte (value
);
5097 do_set_arena_test (value
);
5102 do_set_arena_max (value
);
5105 __libc_lock_unlock (av
->mutex
);
5108 libc_hidden_def (__libc_mallopt
)
5112 -------------------- Alternative MORECORE functions --------------------
5117 General Requirements for MORECORE.
5119 The MORECORE function must have the following properties:
5121 If MORECORE_CONTIGUOUS is false:
5123 * MORECORE must allocate in multiples of pagesize. It will
5124 only be called with arguments that are multiples of pagesize.
5126 * MORECORE(0) must return an address that is at least
5127 MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
5129 else (i.e. If MORECORE_CONTIGUOUS is true):
5131 * Consecutive calls to MORECORE with positive arguments
5132 return increasing addresses, indicating that space has been
5133 contiguously extended.
5135 * MORECORE need not allocate in multiples of pagesize.
5136 Calls to MORECORE need not have args of multiples of pagesize.
5138 * MORECORE need not page-align.
5142 * MORECORE may allocate more memory than requested. (Or even less,
5143 but this will generally result in a malloc failure.)
5145 * MORECORE must not allocate memory when given argument zero, but
5146 instead return one past the end address of memory from previous
5147 nonzero call. This malloc does NOT call MORECORE(0)
5148 until at least one call with positive arguments is made, so
5149 the initial value returned is not important.
5151 * Even though consecutive calls to MORECORE need not return contiguous
5152 addresses, it must be OK for malloc'ed chunks to span multiple
5153 regions in those cases where they do happen to be contiguous.
5155 * MORECORE need not handle negative arguments -- it may instead
5156 just return MORECORE_FAILURE when given negative arguments.
5157 Negative arguments are always multiples of pagesize. MORECORE
5158 must not misinterpret negative args as large positive unsigned
5159 args. You can suppress all such calls from even occurring by defining
5160 MORECORE_CANNOT_TRIM,
5162 There is some variation across systems about the type of the
5163 argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
5164 actually be size_t, because sbrk supports negative args, so it is
5165 normally the signed type of the same width as size_t (sometimes
5166 declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
5167 matter though. Internally, we use "long" as arguments, which should
5168 work across all reasonable possibilities.
5170 Additionally, if MORECORE ever returns failure for a positive
5171 request, then mmap is used as a noncontiguous system allocator. This
5172 is a useful backup strategy for systems with holes in address spaces
5173 -- in this case sbrk cannot contiguously expand the heap, but mmap
5174 may be able to map noncontiguous space.
5176 If you'd like mmap to ALWAYS be used, you can define MORECORE to be
5177 a function that always returns MORECORE_FAILURE.
5179 If you are using this malloc with something other than sbrk (or its
5180 emulation) to supply memory regions, you probably want to set
5181 MORECORE_CONTIGUOUS as false. As an example, here is a custom
5182 allocator kindly contributed for pre-OSX macOS. It uses virtually
5183 but not necessarily physically contiguous non-paged memory (locked
5184 in, present and won't get swapped out). You can use it by
5185 uncommenting this section, adding some #includes, and setting up the
5186 appropriate defines above:
5188 *#define MORECORE osMoreCore
5189 *#define MORECORE_CONTIGUOUS 0
5191 There is also a shutdown routine that should somehow be called for
5192 cleanup upon program exit.
5194 *#define MAX_POOL_ENTRIES 100
5195 *#define MINIMUM_MORECORE_SIZE (64 * 1024)
5196 static int next_os_pool;
5197 void *our_os_pools[MAX_POOL_ENTRIES];
5199 void *osMoreCore(int size)
5202 static void *sbrk_top = 0;
5206 if (size < MINIMUM_MORECORE_SIZE)
5207 size = MINIMUM_MORECORE_SIZE;
5208 if (CurrentExecutionLevel() == kTaskLevel)
5209 ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
5212 return (void *) MORECORE_FAILURE;
5214 // save ptrs so they can be freed during cleanup
5215 our_os_pools[next_os_pool] = ptr;
5217 ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
5218 sbrk_top = (char *) ptr + size;
5223 // we don't currently support shrink behavior
5224 return (void *) MORECORE_FAILURE;
5232 // cleanup any allocated memory pools
5233 // called as last thing before shutting down driver
5235 void osCleanupMem(void)
5239 for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
5242 PoolDeallocate(*ptr);
5252 extern char **__libc_argv attribute_hidden
;
5255 malloc_printerr (const char *str
)
5257 __libc_message (do_abort
, "%s\n", str
);
5258 __builtin_unreachable ();
5261 /* We need a wrapper function for one of the additions of POSIX. */
5263 __posix_memalign (void **memptr
, size_t alignment
, size_t size
)
5267 /* Test whether the SIZE argument is valid. It must be a power of
5268 two multiple of sizeof (void *). */
5269 if (alignment
% sizeof (void *) != 0
5270 || !powerof2 (alignment
/ sizeof (void *))
5275 void *address
= RETURN_ADDRESS (0);
5276 mem
= _mid_memalign (alignment
, size
, address
);
5286 weak_alias (__posix_memalign
, posix_memalign
)
5290 __malloc_info (int options
, FILE *fp
)
5292 /* For now, at least. */
5297 size_t total_nblocks
= 0;
5298 size_t total_nfastblocks
= 0;
5299 size_t total_avail
= 0;
5300 size_t total_fastavail
= 0;
5301 size_t total_system
= 0;
5302 size_t total_max_system
= 0;
5303 size_t total_aspace
= 0;
5304 size_t total_aspace_mprotect
= 0;
5308 if (__malloc_initialized
< 0)
5311 fputs ("<malloc version=\"1\">\n", fp
);
5313 /* Iterate over all arenas currently in use. */
5314 mstate ar_ptr
= &main_arena
;
5317 fprintf (fp
, "<heap nr=\"%d\">\n<sizes>\n", n
++);
5320 size_t nfastblocks
= 0;
5322 size_t fastavail
= 0;
5329 } sizes
[NFASTBINS
+ NBINS
- 1];
5330 #define nsizes (sizeof (sizes) / sizeof (sizes[0]))
5332 __libc_lock_lock (ar_ptr
->mutex
);
5334 for (size_t i
= 0; i
< NFASTBINS
; ++i
)
5336 mchunkptr p
= fastbin (ar_ptr
, i
);
5339 size_t nthissize
= 0;
5340 size_t thissize
= chunksize (p
);
5348 fastavail
+= nthissize
* thissize
;
5349 nfastblocks
+= nthissize
;
5350 sizes
[i
].from
= thissize
- (MALLOC_ALIGNMENT
- 1);
5351 sizes
[i
].to
= thissize
;
5352 sizes
[i
].count
= nthissize
;
5355 sizes
[i
].from
= sizes
[i
].to
= sizes
[i
].count
= 0;
5357 sizes
[i
].total
= sizes
[i
].count
* sizes
[i
].to
;
5362 struct malloc_chunk
*r
;
5364 for (size_t i
= 1; i
< NBINS
; ++i
)
5366 bin
= bin_at (ar_ptr
, i
);
5368 sizes
[NFASTBINS
- 1 + i
].from
= ~((size_t) 0);
5369 sizes
[NFASTBINS
- 1 + i
].to
= sizes
[NFASTBINS
- 1 + i
].total
5370 = sizes
[NFASTBINS
- 1 + i
].count
= 0;
5375 size_t r_size
= chunksize_nomask (r
);
5376 ++sizes
[NFASTBINS
- 1 + i
].count
;
5377 sizes
[NFASTBINS
- 1 + i
].total
+= r_size
;
5378 sizes
[NFASTBINS
- 1 + i
].from
5379 = MIN (sizes
[NFASTBINS
- 1 + i
].from
, r_size
);
5380 sizes
[NFASTBINS
- 1 + i
].to
= MAX (sizes
[NFASTBINS
- 1 + i
].to
,
5386 if (sizes
[NFASTBINS
- 1 + i
].count
== 0)
5387 sizes
[NFASTBINS
- 1 + i
].from
= 0;
5388 nblocks
+= sizes
[NFASTBINS
- 1 + i
].count
;
5389 avail
+= sizes
[NFASTBINS
- 1 + i
].total
;
5392 __libc_lock_unlock (ar_ptr
->mutex
);
5394 total_nfastblocks
+= nfastblocks
;
5395 total_fastavail
+= fastavail
;
5397 total_nblocks
+= nblocks
;
5398 total_avail
+= avail
;
5400 for (size_t i
= 0; i
< nsizes
; ++i
)
5401 if (sizes
[i
].count
!= 0 && i
!= NFASTBINS
)
5403 <size from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5404 sizes
[i
].from
, sizes
[i
].to
, sizes
[i
].total
, sizes
[i
].count
);
5406 if (sizes
[NFASTBINS
].count
!= 0)
5408 <unsorted from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5409 sizes
[NFASTBINS
].from
, sizes
[NFASTBINS
].to
,
5410 sizes
[NFASTBINS
].total
, sizes
[NFASTBINS
].count
);
5412 total_system
+= ar_ptr
->system_mem
;
5413 total_max_system
+= ar_ptr
->max_system_mem
;
5416 "</sizes>\n<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5417 "<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5418 "<system type=\"current\" size=\"%zu\"/>\n"
5419 "<system type=\"max\" size=\"%zu\"/>\n",
5420 nfastblocks
, fastavail
, nblocks
, avail
,
5421 ar_ptr
->system_mem
, ar_ptr
->max_system_mem
);
5423 if (ar_ptr
!= &main_arena
)
5425 heap_info
*heap
= heap_for_ptr (top (ar_ptr
));
5427 "<aspace type=\"total\" size=\"%zu\"/>\n"
5428 "<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5429 heap
->size
, heap
->mprotect_size
);
5430 total_aspace
+= heap
->size
;
5431 total_aspace_mprotect
+= heap
->mprotect_size
;
5436 "<aspace type=\"total\" size=\"%zu\"/>\n"
5437 "<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5438 ar_ptr
->system_mem
, ar_ptr
->system_mem
);
5439 total_aspace
+= ar_ptr
->system_mem
;
5440 total_aspace_mprotect
+= ar_ptr
->system_mem
;
5443 fputs ("</heap>\n", fp
);
5444 ar_ptr
= ar_ptr
->next
;
5446 while (ar_ptr
!= &main_arena
);
5449 "<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5450 "<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5451 "<total type=\"mmap\" count=\"%d\" size=\"%zu\"/>\n"
5452 "<system type=\"current\" size=\"%zu\"/>\n"
5453 "<system type=\"max\" size=\"%zu\"/>\n"
5454 "<aspace type=\"total\" size=\"%zu\"/>\n"
5455 "<aspace type=\"mprotect\" size=\"%zu\"/>\n"
5457 total_nfastblocks
, total_fastavail
, total_nblocks
, total_avail
,
5458 mp_
.n_mmaps
, mp_
.mmapped_mem
,
5459 total_system
, total_max_system
,
5460 total_aspace
, total_aspace_mprotect
);
5464 weak_alias (__malloc_info
, malloc_info
)
5467 strong_alias (__libc_calloc
, __calloc
) weak_alias (__libc_calloc
, calloc
)
5468 strong_alias (__libc_free
, __free
) strong_alias (__libc_free
, free
)
5469 strong_alias (__libc_malloc
, __malloc
) strong_alias (__libc_malloc
, malloc
)
5470 strong_alias (__libc_memalign
, __memalign
)
5471 weak_alias (__libc_memalign
, memalign
)
5472 strong_alias (__libc_realloc
, __realloc
) strong_alias (__libc_realloc
, realloc
)
5473 strong_alias (__libc_valloc
, __valloc
) weak_alias (__libc_valloc
, valloc
)
5474 strong_alias (__libc_pvalloc
, __pvalloc
) weak_alias (__libc_pvalloc
, pvalloc
)
5475 strong_alias (__libc_mallinfo
, __mallinfo
)
5476 weak_alias (__libc_mallinfo
, mallinfo
)
5477 strong_alias (__libc_mallopt
, __mallopt
) weak_alias (__libc_mallopt
, mallopt
)
5479 weak_alias (__malloc_stats
, malloc_stats
)
5480 weak_alias (__malloc_usable_size
, malloc_usable_size
)
5481 weak_alias (__malloc_trim
, malloc_trim
)
5483 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
5484 compat_symbol (libc
, __libc_free
, cfree
, GLIBC_2_0
);
5487 /* ------------------------------------------------------------
5490 [see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]