1 /* Malloc implementation for multiple threads without lock contention.
2 Copyright (C) 1996-2021 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 <https://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 */
228 #include <shlib-compat.h>
233 /* For va_arg, va_start, va_end. */
236 /* For MIN, MAX, powerof2. */
237 #include <sys/param.h>
239 /* For ALIGN_UP et. al. */
240 #include <libc-pointer-arith.h>
242 /* For DIAG_PUSH/POP_NEEDS_COMMENT et al. */
243 #include <libc-diag.h>
245 /* For memory tagging. */
246 #include <libc-mtag.h>
248 #include <malloc/malloc-internal.h>
250 /* For SINGLE_THREAD_P. */
251 #include <sysdep-cancel.h>
253 #include <libc-internal.h>
255 /* For tcache double-free check. */
256 #include <random-bits.h>
257 #include <sys/random.h>
262 Because freed chunks may be overwritten with bookkeeping fields, this
263 malloc will often die when freed memory is overwritten by user
264 programs. This can be very effective (albeit in an annoying way)
265 in helping track down dangling pointers.
267 If you compile with -DMALLOC_DEBUG, a number of assertion checks are
268 enabled that will catch more memory errors. You probably won't be
269 able to make much sense of the actual assertion errors, but they
270 should help you locate incorrectly overwritten memory. The checking
271 is fairly extensive, and will slow down execution
272 noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
273 will attempt to check every non-mmapped allocated and free chunk in
274 the course of computing the summmaries. (By nature, mmapped regions
275 cannot be checked very much automatically.)
277 Setting MALLOC_DEBUG may also be helpful if you are trying to modify
278 this code. The assertions in the check routines spell out in more
279 detail the assumptions and invariants underlying the algorithms.
281 Setting MALLOC_DEBUG does NOT provide an automated mechanism for
282 checking that all accesses to malloced memory stay within their
283 bounds. However, there are several add-ons and adaptations of this
284 or other mallocs available that do this.
288 #define MALLOC_DEBUG 0
292 # define __assert_fail(assertion, file, line, function) \
293 __malloc_assert(assertion, file, line, function)
295 extern const char *__progname
;
298 __malloc_assert (const char *assertion
, const char *file
, unsigned int line
,
299 const char *function
)
301 (void) __fxprintf (NULL
, "%s%s%s:%u: %s%sAssertion `%s' failed.\n",
302 __progname
, __progname
[0] ? ": " : "",
304 function
? function
: "", function
? ": " : "",
312 /* We want 64 entries. This is an arbitrary limit, which tunables can reduce. */
313 # define TCACHE_MAX_BINS 64
314 # define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1)
316 /* Only used to pre-fill the tunables. */
317 # define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
319 /* When "x" is from chunksize(). */
320 # define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT)
321 /* When "x" is a user-provided size. */
322 # define usize2tidx(x) csize2tidx (request2size (x))
324 /* With rounding and alignment, the bins are...
325 idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit)
326 idx 1 bytes 25..40 or 13..20
327 idx 2 bytes 41..56 or 21..28
330 /* This is another arbitrary limit, which tunables can change. Each
331 tcache bin will hold at most this number of chunks. */
332 # define TCACHE_FILL_COUNT 7
334 /* Maximum chunks in tcache bins for tunables. This value must fit the range
335 of tcache->counts[] entries, else they may overflow. */
336 # define MAX_TCACHE_COUNT UINT16_MAX
340 Use randomness from ASLR (mmap_base) to protect single-linked lists
341 of Fast-Bins and TCache. That is, mask the "next" pointers of the
342 lists' chunks, and also perform allocation alignment checks on them.
343 This mechanism reduces the risk of pointer hijacking, as was done with
344 Safe-Unlinking in the double-linked lists of Small-Bins.
345 It assumes a minimum page size of 4096 bytes (12 bits). Systems with
346 larger pages provide less entropy, although the pointer mangling
348 #define PROTECT_PTR(pos, ptr) \
349 ((__typeof (ptr)) ((((size_t) pos) >> 12) ^ ((size_t) ptr)))
350 #define REVEAL_PTR(ptr) PROTECT_PTR (&ptr, ptr)
353 The REALLOC_ZERO_BYTES_FREES macro controls the behavior of realloc (p, 0)
354 when p is nonnull. If the macro is nonzero, the realloc call returns NULL;
355 otherwise, the call returns what malloc (0) would. In either case,
356 p is freed. Glibc uses a nonzero REALLOC_ZERO_BYTES_FREES, which
357 implements common historical practice.
359 ISO C17 says the realloc call has implementation-defined behavior,
360 and it might not even free p.
363 #ifndef REALLOC_ZERO_BYTES_FREES
364 #define REALLOC_ZERO_BYTES_FREES 1
368 TRIM_FASTBINS controls whether free() of a very small chunk can
369 immediately lead to trimming. Setting to true (1) can reduce memory
370 footprint, but will almost always slow down programs that use a lot
373 Define this only if you are willing to give up some speed to more
374 aggressively reduce system-level memory footprint when releasing
375 memory in programs that use many small chunks. You can get
376 essentially the same effect by setting MXFAST to 0, but this can
377 lead to even greater slowdowns in programs using many small chunks.
378 TRIM_FASTBINS is an in-between compile-time option, that disables
379 only those chunks bordering topmost memory from being placed in
383 #ifndef TRIM_FASTBINS
384 #define TRIM_FASTBINS 0
388 /* Definition for getting more memory from the OS. */
389 #define MORECORE (*__morecore)
390 #define MORECORE_FAILURE 0
391 void * __default_morecore (ptrdiff_t);
392 void *(*__morecore
)(ptrdiff_t) = __default_morecore
;
394 /* Memory tagging. */
396 /* Some systems support the concept of tagging (sometimes known as
397 coloring) memory locations on a fine grained basis. Each memory
398 location is given a color (normally allocated randomly) and
399 pointers are also colored. When the pointer is dereferenced, the
400 pointer's color is checked against the memory's color and if they
401 differ the access is faulted (sometimes lazily).
403 We use this in glibc by maintaining a single color for the malloc
404 data structures that are interleaved with the user data and then
405 assigning separate colors for each block allocation handed out. In
406 this way simple buffer overruns will be rapidly detected. When
407 memory is freed, the memory is recolored back to the glibc default
408 so that simple use-after-free errors can also be detected.
410 If memory is reallocated the buffer is recolored even if the
411 address remains the same. This has a performance impact, but
412 guarantees that the old pointer cannot mistakenly be reused (code
413 that compares old against new will see a mismatch and will then
414 need to behave as though realloc moved the data to a new location).
416 Internal API for memory tagging support.
418 The aim is to keep the code for memory tagging support as close to
419 the normal APIs in glibc as possible, so that if tagging is not
420 enabled in the library, or is disabled at runtime then standard
421 operations can continue to be used. Support macros are used to do
424 void *tag_new_zero_region (void *ptr, size_t size)
426 Allocates a new tag, colors the memory with that tag, zeros the
427 memory and returns a pointer that is correctly colored for that
428 location. The non-tagging version will simply call memset with 0.
430 void *tag_region (void *ptr, size_t size)
432 Color the region of memory pointed to by PTR and size SIZE with
433 the color of PTR. Returns the original pointer.
435 void *tag_new_usable (void *ptr)
437 Allocate a new random color and use it to color the user region of
438 a chunk; this may include data from the subsequent chunk's header
439 if tagging is sufficiently fine grained. Returns PTR suitably
440 recolored for accessing the memory there.
442 void *tag_at (void *ptr)
444 Read the current color of the memory at the address pointed to by
445 PTR (ignoring it's current color) and return PTR recolored to that
446 color. PTR must be valid address in all other respects. When
447 tagging is not enabled, it simply returns the original pointer.
451 static bool mtag_enabled
= false;
452 static int mtag_mmap_flags
= 0;
454 # define mtag_enabled false
455 # define mtag_mmap_flags 0
458 static __always_inline
void *
459 tag_region (void *ptr
, size_t size
)
461 if (__glibc_unlikely (mtag_enabled
))
462 return __libc_mtag_tag_region (ptr
, size
);
466 static __always_inline
void *
467 tag_new_zero_region (void *ptr
, size_t size
)
469 if (__glibc_unlikely (mtag_enabled
))
470 return __libc_mtag_tag_zero_region (__libc_mtag_new_tag (ptr
), size
);
471 return memset (ptr
, 0, size
);
476 tag_new_usable (void *ptr
);
478 static __always_inline
void *
481 if (__glibc_unlikely (mtag_enabled
))
482 return __libc_mtag_address_get_tag (ptr
);
489 MORECORE-related declarations. By default, rely on sbrk
494 MORECORE is the name of the routine to call to obtain more memory
495 from the system. See below for general guidance on writing
496 alternative MORECORE functions, as well as a version for WIN32 and a
497 sample version for pre-OSX macos.
501 #define MORECORE sbrk
505 MORECORE_FAILURE is the value returned upon failure of MORECORE
506 as well as mmap. Since it cannot be an otherwise valid memory address,
507 and must reflect values of standard sys calls, you probably ought not
511 #ifndef MORECORE_FAILURE
512 #define MORECORE_FAILURE (-1)
516 If MORECORE_CONTIGUOUS is true, take advantage of fact that
517 consecutive calls to MORECORE with positive arguments always return
518 contiguous increasing addresses. This is true of unix sbrk. Even
519 if not defined, when regions happen to be contiguous, malloc will
520 permit allocations spanning regions obtained from different
521 calls. But defining this when applicable enables some stronger
522 consistency checks and space efficiencies.
525 #ifndef MORECORE_CONTIGUOUS
526 #define MORECORE_CONTIGUOUS 1
530 Define MORECORE_CANNOT_TRIM if your version of MORECORE
531 cannot release space back to the system when given negative
532 arguments. This is generally necessary only if you are using
533 a hand-crafted MORECORE function that cannot handle negative arguments.
536 /* #define MORECORE_CANNOT_TRIM */
538 /* MORECORE_CLEARS (default 1)
539 The degree to which the routine mapped to MORECORE zeroes out
540 memory: never (0), only for newly allocated space (1) or always
541 (2). The distinction between (1) and (2) is necessary because on
542 some systems, if the application first decrements and then
543 increments the break value, the contents of the reallocated space
547 #ifndef MORECORE_CLEARS
548 # define MORECORE_CLEARS 1
553 MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
554 sbrk fails, and mmap is used as a backup. The value must be a
555 multiple of page size. This backup strategy generally applies only
556 when systems have "holes" in address space, so sbrk cannot perform
557 contiguous expansion, but there is still space available on system.
558 On systems for which this is known to be useful (i.e. most linux
559 kernels), this occurs only when programs allocate huge amounts of
560 memory. Between this, and the fact that mmap regions tend to be
561 limited, the size should be large, to avoid too many mmap calls and
562 thus avoid running out of kernel resources. */
564 #ifndef MMAP_AS_MORECORE_SIZE
565 #define MMAP_AS_MORECORE_SIZE (1024 * 1024)
569 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
574 #define HAVE_MREMAP 0
577 /* We may need to support __malloc_initialize_hook for backwards
580 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
581 # define HAVE_MALLOC_INIT_HOOK 1
583 # define HAVE_MALLOC_INIT_HOOK 0
588 This version of malloc supports the standard SVID/XPG mallinfo
589 routine that returns a struct containing usage properties and
590 statistics. It should work on any SVID/XPG compliant system that has
591 a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
592 install such a thing yourself, cut out the preliminary declarations
593 as described above and below and save them in a malloc.h file. But
594 there's no compelling reason to bother to do this.)
596 The main declaration needed is the mallinfo struct that is returned
597 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
598 bunch of fields that are not even meaningful in this version of
599 malloc. These fields are are instead filled by mallinfo() with
600 other numbers that might be of interest.
604 /* ---------- description of public routines ------------ */
608 Returns a pointer to a newly allocated chunk of at least n bytes, or null
609 if no space is available. Additionally, on failure, errno is
610 set to ENOMEM on ANSI C systems.
612 If n is zero, malloc returns a minimum-sized chunk. (The minimum
613 size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
614 systems.) On most systems, size_t is an unsigned type, so calls
615 with negative arguments are interpreted as requests for huge amounts
616 of space, which will often fail. The maximum supported value of n
617 differs across systems, but is in all cases less than the maximum
618 representable value of a size_t.
620 void* __libc_malloc(size_t);
621 libc_hidden_proto (__libc_malloc
)
625 Releases the chunk of memory pointed to by p, that had been previously
626 allocated using malloc or a related routine such as realloc.
627 It has no effect if p is null. It can have arbitrary (i.e., bad!)
628 effects if p has already been freed.
630 Unless disabled (using mallopt), freeing very large spaces will
631 when possible, automatically trigger operations that give
632 back unused memory to the system, thus reducing program footprint.
634 void __libc_free(void*);
635 libc_hidden_proto (__libc_free
)
638 calloc(size_t n_elements, size_t element_size);
639 Returns a pointer to n_elements * element_size bytes, with all locations
642 void* __libc_calloc(size_t, size_t);
645 realloc(void* p, size_t n)
646 Returns a pointer to a chunk of size n that contains the same data
647 as does chunk p up to the minimum of (n, p's size) bytes, or null
648 if no space is available.
650 The returned pointer may or may not be the same as p. The algorithm
651 prefers extending p when possible, otherwise it employs the
652 equivalent of a malloc-copy-free sequence.
654 If p is null, realloc is equivalent to malloc.
656 If space is not available, realloc returns null, errno is set (if on
657 ANSI) and p is NOT freed.
659 if n is for fewer bytes than already held by p, the newly unused
660 space is lopped off and freed if possible. Unless the #define
661 REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
662 zero (re)allocates a minimum-sized chunk.
664 Large chunks that were internally obtained via mmap will always be
665 grown using malloc-copy-free sequences unless the system supports
666 MREMAP (currently only linux).
668 The old unix realloc convention of allowing the last-free'd chunk
669 to be used as an argument to realloc is not supported.
671 void* __libc_realloc(void*, size_t);
672 libc_hidden_proto (__libc_realloc
)
675 memalign(size_t alignment, size_t n);
676 Returns a pointer to a newly allocated chunk of n bytes, aligned
677 in accord with the alignment argument.
679 The alignment argument should be a power of two. If the argument is
680 not a power of two, the nearest greater power is used.
681 8-byte alignment is guaranteed by normal malloc calls, so don't
682 bother calling memalign with an argument of 8 or less.
684 Overreliance on memalign is a sure way to fragment space.
686 void* __libc_memalign(size_t, size_t);
687 libc_hidden_proto (__libc_memalign
)
691 Equivalent to memalign(pagesize, n), where pagesize is the page
692 size of the system. If the pagesize is unknown, 4096 is used.
694 void* __libc_valloc(size_t);
699 mallopt(int parameter_number, int parameter_value)
700 Sets tunable parameters The format is to provide a
701 (parameter-number, parameter-value) pair. mallopt then sets the
702 corresponding parameter to the argument value if it can (i.e., so
703 long as the value is meaningful), and returns 1 if successful else
704 0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
705 normally defined in malloc.h. Only one of these (M_MXFAST) is used
706 in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
707 so setting them has no effect. But this malloc also supports four
708 other options in mallopt. See below for details. Briefly, supported
709 parameters are as follows (listed defaults are for "typical"
712 Symbol param # default allowed param values
713 M_MXFAST 1 64 0-80 (0 disables fastbins)
714 M_TRIM_THRESHOLD -1 128*1024 any (-1U disables trimming)
716 M_MMAP_THRESHOLD -3 128*1024 any (or 0 if no MMAP support)
717 M_MMAP_MAX -4 65536 any (0 disables use of mmap)
719 int __libc_mallopt(int, int);
720 libc_hidden_proto (__libc_mallopt
)
725 Returns (by copy) a struct containing various summary statistics:
727 arena: current total non-mmapped bytes allocated from system
728 ordblks: the number of free chunks
729 smblks: the number of fastbin blocks (i.e., small chunks that
730 have been freed but not use resused or consolidated)
731 hblks: current number of mmapped regions
732 hblkhd: total bytes held in mmapped regions
734 fsmblks: total bytes held in fastbin blocks
735 uordblks: current total allocated space (normal or mmapped)
736 fordblks: total free space
737 keepcost: the maximum number of bytes that could ideally be released
738 back to system via malloc_trim. ("ideally" means that
739 it ignores page restrictions etc.)
741 Because these fields are ints, but internal bookkeeping may
742 be kept as longs, the reported values may wrap around zero and
745 struct mallinfo2
__libc_mallinfo2(void);
746 libc_hidden_proto (__libc_mallinfo2
)
748 struct mallinfo
__libc_mallinfo(void);
753 Equivalent to valloc(minimum-page-that-holds(n)), that is,
754 round up n to nearest pagesize.
756 void* __libc_pvalloc(size_t);
759 malloc_trim(size_t pad);
761 If possible, gives memory back to the system (via negative
762 arguments to sbrk) if there is unused memory at the `high' end of
763 the malloc pool. You can call this after freeing large blocks of
764 memory to potentially reduce the system-level memory requirements
765 of a program. However, it cannot guarantee to reduce memory. Under
766 some allocation patterns, some large free blocks of memory will be
767 locked between two used chunks, so they cannot be given back to
770 The `pad' argument to malloc_trim represents the amount of free
771 trailing space to leave untrimmed. If this argument is zero,
772 only the minimum amount of memory to maintain internal data
773 structures will be left (one page or less). Non-zero arguments
774 can be supplied to maintain enough trailing space to service
775 future expected allocations without having to re-obtain memory
778 Malloc_trim returns 1 if it actually released any memory, else 0.
779 On systems that do not support "negative sbrks", it will always
782 int __malloc_trim(size_t);
785 malloc_usable_size(void* p);
787 Returns the number of bytes you can actually use in
788 an allocated chunk, which may be more than you requested (although
789 often not) due to alignment and minimum size constraints.
790 You can use this many bytes without worrying about
791 overwriting other allocated objects. This is not a particularly great
792 programming practice. malloc_usable_size can be more useful in
793 debugging and assertions, for example:
796 assert(malloc_usable_size(p) >= 256);
799 size_t __malloc_usable_size(void*);
803 Prints on stderr the amount of space obtained from the system (both
804 via sbrk and mmap), the maximum amount (which may be more than
805 current if malloc_trim and/or munmap got called), and the current
806 number of bytes allocated via malloc (or realloc, etc) but not yet
807 freed. Note that this is the number of bytes allocated, not the
808 number requested. It will be larger than the number requested
809 because of alignment and bookkeeping overhead. Because it includes
810 alignment wastage as being in use, this figure may be greater than
811 zero even when no user-level chunks are allocated.
813 The reported current and maximum system memory can be inaccurate if
814 a program makes other calls to system memory allocation functions
815 (normally sbrk) outside of malloc.
817 malloc_stats prints only the most commonly interesting statistics.
818 More information can be obtained by calling mallinfo.
821 void __malloc_stats(void);
824 posix_memalign(void **memptr, size_t alignment, size_t size);
826 POSIX wrapper like memalign(), checking for validity of size.
828 int __posix_memalign(void **, size_t, size_t);
830 /* mallopt tuning options */
833 M_MXFAST is the maximum request size used for "fastbins", special bins
834 that hold returned chunks without consolidating their spaces. This
835 enables future requests for chunks of the same size to be handled
836 very quickly, but can increase fragmentation, and thus increase the
837 overall memory footprint of a program.
839 This malloc manages fastbins very conservatively yet still
840 efficiently, so fragmentation is rarely a problem for values less
841 than or equal to the default. The maximum supported value of MXFAST
842 is 80. You wouldn't want it any higher than this anyway. Fastbins
843 are designed especially for use with many small structs, objects or
844 strings -- the default handles structs/objects/arrays with sizes up
845 to 8 4byte fields, or small strings representing words, tokens,
846 etc. Using fastbins for larger objects normally worsens
847 fragmentation without improving speed.
849 M_MXFAST is set in REQUEST size units. It is internally used in
850 chunksize units, which adds padding and alignment. You can reduce
851 M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
852 algorithm to be a closer approximation of fifo-best-fit in all cases,
853 not just for larger requests, but will generally cause it to be
858 /* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
863 #ifndef DEFAULT_MXFAST
864 #define DEFAULT_MXFAST (64 * SIZE_SZ / 4)
869 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
870 to keep before releasing via malloc_trim in free().
872 Automatic trimming is mainly useful in long-lived programs.
873 Because trimming via sbrk can be slow on some systems, and can
874 sometimes be wasteful (in cases where programs immediately
875 afterward allocate more large chunks) the value should be high
876 enough so that your overall system performance would improve by
877 releasing this much memory.
879 The trim threshold and the mmap control parameters (see below)
880 can be traded off with one another. Trimming and mmapping are
881 two different ways of releasing unused memory back to the
882 system. Between these two, it is often possible to keep
883 system-level demands of a long-lived program down to a bare
884 minimum. For example, in one test suite of sessions measuring
885 the XF86 X server on Linux, using a trim threshold of 128K and a
886 mmap threshold of 192K led to near-minimal long term resource
889 If you are using this malloc in a long-lived program, it should
890 pay to experiment with these values. As a rough guide, you
891 might set to a value close to the average size of a process
892 (program) running on your system. Releasing this much memory
893 would allow such a process to run in memory. Generally, it's
894 worth it to tune for trimming rather tham memory mapping when a
895 program undergoes phases where several large chunks are
896 allocated and released in ways that can reuse each other's
897 storage, perhaps mixed with phases where there are no such
898 chunks at all. And in well-behaved long-lived programs,
899 controlling release of large blocks via trimming versus mapping
902 However, in most programs, these parameters serve mainly as
903 protection against the system-level effects of carrying around
904 massive amounts of unneeded memory. Since frequent calls to
905 sbrk, mmap, and munmap otherwise degrade performance, the default
906 parameters are set to relatively high values that serve only as
909 The trim value It must be greater than page size to have any useful
910 effect. To disable trimming completely, you can set to
913 Trim settings interact with fastbin (MXFAST) settings: Unless
914 TRIM_FASTBINS is defined, automatic trimming never takes place upon
915 freeing a chunk with size less than or equal to MXFAST. Trimming is
916 instead delayed until subsequent freeing of larger chunks. However,
917 you can still force an attempted trim by calling malloc_trim.
919 Also, trimming is not generally possible in cases where
920 the main arena is obtained via mmap.
922 Note that the trick some people use of mallocing a huge space and
923 then freeing it at program startup, in an attempt to reserve system
924 memory, doesn't have the intended effect under automatic trimming,
925 since that memory will immediately be returned to the system.
928 #define M_TRIM_THRESHOLD -1
930 #ifndef DEFAULT_TRIM_THRESHOLD
931 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
935 M_TOP_PAD is the amount of extra `padding' space to allocate or
936 retain whenever sbrk is called. It is used in two ways internally:
938 * When sbrk is called to extend the top of the arena to satisfy
939 a new malloc request, this much padding is added to the sbrk
942 * When malloc_trim is called automatically from free(),
943 it is used as the `pad' argument.
945 In both cases, the actual amount of padding is rounded
946 so that the end of the arena is always a system page boundary.
948 The main reason for using padding is to avoid calling sbrk so
949 often. Having even a small pad greatly reduces the likelihood
950 that nearly every malloc request during program start-up (or
951 after trimming) will invoke sbrk, which needlessly wastes
954 Automatic rounding-up to page-size units is normally sufficient
955 to avoid measurable overhead, so the default is 0. However, in
956 systems where sbrk is relatively slow, it can pay to increase
957 this value, at the expense of carrying around more memory than
963 #ifndef DEFAULT_TOP_PAD
964 #define DEFAULT_TOP_PAD (0)
968 MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
969 adjusted MMAP_THRESHOLD.
972 #ifndef DEFAULT_MMAP_THRESHOLD_MIN
973 #define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
976 #ifndef DEFAULT_MMAP_THRESHOLD_MAX
977 /* For 32-bit platforms we cannot increase the maximum mmap
978 threshold much because it is also the minimum value for the
979 maximum heap size and its alignment. Going above 512k (i.e., 1M
980 for new heaps) wastes too much address space. */
981 # if __WORDSIZE == 32
982 # define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
984 # define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
989 M_MMAP_THRESHOLD is the request size threshold for using mmap()
990 to service a request. Requests of at least this size that cannot
991 be allocated using already-existing space will be serviced via mmap.
992 (If enough normal freed space already exists it is used instead.)
994 Using mmap segregates relatively large chunks of memory so that
995 they can be individually obtained and released from the host
996 system. A request serviced through mmap is never reused by any
997 other request (at least not directly; the system may just so
998 happen to remap successive requests to the same locations).
1000 Segregating space in this way has the benefits that:
1002 1. Mmapped space can ALWAYS be individually released back
1003 to the system, which helps keep the system level memory
1004 demands of a long-lived program low.
1005 2. Mapped memory can never become `locked' between
1006 other chunks, as can happen with normally allocated chunks, which
1007 means that even trimming via malloc_trim would not release them.
1008 3. On some systems with "holes" in address spaces, mmap can obtain
1009 memory that sbrk cannot.
1011 However, it has the disadvantages that:
1013 1. The space cannot be reclaimed, consolidated, and then
1014 used to service later requests, as happens with normal chunks.
1015 2. It can lead to more wastage because of mmap page alignment
1017 3. It causes malloc performance to be more dependent on host
1018 system memory management support routines which may vary in
1019 implementation quality and may impose arbitrary
1020 limitations. Generally, servicing a request via normal
1021 malloc steps is faster than going through a system's mmap.
1023 The advantages of mmap nearly always outweigh disadvantages for
1024 "large" chunks, but the value of "large" varies across systems. The
1025 default is an empirically derived value that works well in most
1030 The above was written in 2001. Since then the world has changed a lot.
1031 Memory got bigger. Applications got bigger. The virtual address space
1032 layout in 32 bit linux changed.
1034 In the new situation, brk() and mmap space is shared and there are no
1035 artificial limits on brk size imposed by the kernel. What is more,
1036 applications have started using transient allocations larger than the
1037 128Kb as was imagined in 2001.
1039 The price for mmap is also high now; each time glibc mmaps from the
1040 kernel, the kernel is forced to zero out the memory it gives to the
1041 application. Zeroing memory is expensive and eats a lot of cache and
1042 memory bandwidth. This has nothing to do with the efficiency of the
1043 virtual memory system, by doing mmap the kernel just has no choice but
1046 In 2001, the kernel had a maximum size for brk() which was about 800
1047 megabytes on 32 bit x86, at that point brk() would hit the first
1048 mmaped shared libaries and couldn't expand anymore. With current 2.6
1049 kernels, the VA space layout is different and brk() and mmap
1050 both can span the entire heap at will.
1052 Rather than using a static threshold for the brk/mmap tradeoff,
1053 we are now using a simple dynamic one. The goal is still to avoid
1054 fragmentation. The old goals we kept are
1055 1) try to get the long lived large allocations to use mmap()
1056 2) really large allocations should always use mmap()
1057 and we're adding now:
1058 3) transient allocations should use brk() to avoid forcing the kernel
1059 having to zero memory over and over again
1061 The implementation works with a sliding threshold, which is by default
1062 limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
1063 out at 128Kb as per the 2001 default.
1065 This allows us to satisfy requirement 1) under the assumption that long
1066 lived allocations are made early in the process' lifespan, before it has
1067 started doing dynamic allocations of the same size (which will
1068 increase the threshold).
1070 The upperbound on the threshold satisfies requirement 2)
1072 The threshold goes up in value when the application frees memory that was
1073 allocated with the mmap allocator. The idea is that once the application
1074 starts freeing memory of a certain size, it's highly probable that this is
1075 a size the application uses for transient allocations. This estimator
1076 is there to satisfy the new third requirement.
1080 #define M_MMAP_THRESHOLD -3
1082 #ifndef DEFAULT_MMAP_THRESHOLD
1083 #define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
1087 M_MMAP_MAX is the maximum number of requests to simultaneously
1088 service using mmap. This parameter exists because
1089 some systems have a limited number of internal tables for
1090 use by mmap, and using more than a few of them may degrade
1093 The default is set to a value that serves only as a safeguard.
1094 Setting to 0 disables use of mmap for servicing large requests.
1097 #define M_MMAP_MAX -4
1099 #ifndef DEFAULT_MMAP_MAX
1100 #define DEFAULT_MMAP_MAX (65536)
1105 #ifndef RETURN_ADDRESS
1106 #define RETURN_ADDRESS(X_) (NULL)
1109 /* Forward declarations. */
1110 struct malloc_chunk
;
1111 typedef struct malloc_chunk
* mchunkptr
;
1113 /* Internal routines. */
1115 static void* _int_malloc(mstate
, size_t);
1116 static void _int_free(mstate
, mchunkptr
, int);
1117 static void* _int_realloc(mstate
, mchunkptr
, INTERNAL_SIZE_T
,
1119 static void* _int_memalign(mstate
, size_t, size_t);
1120 static void* _mid_memalign(size_t, size_t, void *);
1122 static void malloc_printerr(const char *str
) __attribute__ ((noreturn
));
1124 static void* mem2mem_check(void *p
, size_t sz
);
1125 static void top_check(void);
1126 static void munmap_chunk(mchunkptr p
);
1128 static mchunkptr
mremap_chunk(mchunkptr p
, size_t new_size
);
1131 static void* malloc_check(size_t sz
, const void *caller
);
1132 static void free_check(void* mem
, const void *caller
);
1133 static void* realloc_check(void* oldmem
, size_t bytes
,
1134 const void *caller
);
1135 static void* memalign_check(size_t alignment
, size_t bytes
,
1136 const void *caller
);
1138 /* ------------------ MMAP support ------------------ */
1142 #include <sys/mman.h>
1144 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
1145 # define MAP_ANONYMOUS MAP_ANON
1148 #ifndef MAP_NORESERVE
1149 # define MAP_NORESERVE 0
1152 #define MMAP(addr, size, prot, flags) \
1153 __mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0)
1157 ----------------------- Chunk representations -----------------------
1162 This struct declaration is misleading (but accurate and necessary).
1163 It declares a "view" into memory allowing access to necessary
1164 fields at known offsets from a given base. See explanation below.
1167 struct malloc_chunk
{
1169 INTERNAL_SIZE_T mchunk_prev_size
; /* Size of previous chunk (if free). */
1170 INTERNAL_SIZE_T mchunk_size
; /* Size in bytes, including overhead. */
1172 struct malloc_chunk
* fd
; /* double links -- used only if free. */
1173 struct malloc_chunk
* bk
;
1175 /* Only used for large blocks: pointer to next larger size. */
1176 struct malloc_chunk
* fd_nextsize
; /* double links -- used only if free. */
1177 struct malloc_chunk
* bk_nextsize
;
1182 malloc_chunk details:
1184 (The following includes lightly edited explanations by Colin Plumb.)
1186 Chunks of memory are maintained using a `boundary tag' method as
1187 described in e.g., Knuth or Standish. (See the paper by Paul
1188 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1189 survey of such techniques.) Sizes of free chunks are stored both
1190 in the front of each chunk and at the end. This makes
1191 consolidating fragmented chunks into bigger chunks very fast. The
1192 size fields also hold bits representing whether chunks are free or
1195 An allocated chunk looks like this:
1198 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1199 | Size of previous chunk, if unallocated (P clear) |
1200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1201 | Size of chunk, in bytes |A|M|P|
1202 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1203 | User data starts here... .
1205 . (malloc_usable_size() bytes) .
1207 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1208 | (size of chunk, but used for application data) |
1209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1210 | Size of next chunk, in bytes |A|0|1|
1211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1213 Where "chunk" is the front of the chunk for the purpose of most of
1214 the malloc code, but "mem" is the pointer that is returned to the
1215 user. "Nextchunk" is the beginning of the next contiguous chunk.
1217 Chunks always begin on even word boundaries, so the mem portion
1218 (which is returned to the user) is also on an even word boundary, and
1219 thus at least double-word aligned.
1221 Free chunks are stored in circular doubly-linked lists, and look like this:
1223 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1224 | Size of previous chunk, if unallocated (P clear) |
1225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1226 `head:' | Size of chunk, in bytes |A|0|P|
1227 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1228 | Forward pointer to next chunk in list |
1229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1230 | Back pointer to previous chunk in list |
1231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1232 | Unused space (may be 0 bytes long) .
1235 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1236 `foot:' | Size of chunk, in bytes |
1237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1238 | Size of next chunk, in bytes |A|0|0|
1239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1241 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1242 chunk size (which is always a multiple of two words), is an in-use
1243 bit for the *previous* chunk. If that bit is *clear*, then the
1244 word before the current chunk size contains the previous chunk
1245 size, and can be used to find the front of the previous chunk.
1246 The very first chunk allocated always has this bit set,
1247 preventing access to non-existent (or non-owned) memory. If
1248 prev_inuse is set for any given chunk, then you CANNOT determine
1249 the size of the previous chunk, and might even get a memory
1250 addressing fault when trying to do so.
1252 The A (NON_MAIN_ARENA) bit is cleared for chunks on the initial,
1253 main arena, described by the main_arena variable. When additional
1254 threads are spawned, each thread receives its own arena (up to a
1255 configurable limit, after which arenas are reused for multiple
1256 threads), and the chunks in these arenas have the A bit set. To
1257 find the arena for a chunk on such a non-main arena, heap_for_ptr
1258 performs a bit mask operation and indirection through the ar_ptr
1259 member of the per-heap header heap_info (see arena.c).
1261 Note that the `foot' of the current chunk is actually represented
1262 as the prev_size of the NEXT chunk. This makes it easier to
1263 deal with alignments etc but can be very confusing when trying
1264 to extend or adapt this code.
1266 The three exceptions to all this are:
1268 1. The special chunk `top' doesn't bother using the
1269 trailing size field since there is no next contiguous chunk
1270 that would have to index off it. After initialization, `top'
1271 is forced to always exist. If it would become less than
1272 MINSIZE bytes long, it is replenished.
1274 2. Chunks allocated via mmap, which have the second-lowest-order
1275 bit M (IS_MMAPPED) set in their size fields. Because they are
1276 allocated one-by-one, each must contain its own trailing size
1277 field. If the M bit is set, the other bits are ignored
1278 (because mmapped chunks are neither in an arena, nor adjacent
1279 to a freed chunk). The M bit is also used for chunks which
1280 originally came from a dumped heap via malloc_set_state in
1283 3. Chunks in fastbins are treated as allocated chunks from the
1284 point of view of the chunk allocator. They are consolidated
1285 with their neighbors only in bulk, in malloc_consolidate.
1289 ---------- Size and alignment checks and conversions ----------
1292 /* Conversion from malloc headers to user pointers, and back. When
1293 using memory tagging the user data and the malloc data structure
1294 headers have distinct tags. Converting fully from one to the other
1295 involves extracting the tag at the other address and creating a
1296 suitable pointer using it. That can be quite expensive. There are
1297 cases when the pointers are not dereferenced (for example only used
1298 for alignment check) so the tags are not relevant, and there are
1299 cases when user data is not tagged distinctly from malloc headers
1300 (user data is untagged because tagging is done late in malloc and
1301 early in free). User memory tagging across internal interfaces:
1303 sysmalloc: Returns untagged memory.
1304 _int_malloc: Returns untagged memory.
1305 _int_free: Takes untagged memory.
1306 _int_memalign: Returns untagged memory.
1307 _int_memalign: Returns untagged memory.
1308 _mid_memalign: Returns tagged memory.
1309 _int_realloc: Takes and returns tagged memory.
1312 /* The chunk header is two SIZE_SZ elements, but this is used widely, so
1313 we define it here for clarity later. */
1314 #define CHUNK_HDR_SZ (2 * SIZE_SZ)
1316 /* Convert a chunk address to a user mem pointer without correcting
1318 #define chunk2mem(p) ((void*)((char*)(p) + CHUNK_HDR_SZ))
1320 /* Convert a chunk address to a user mem pointer and extract the right tag. */
1321 #define chunk2mem_tag(p) ((void*)tag_at ((char*)(p) + CHUNK_HDR_SZ))
1323 /* Convert a user mem pointer to a chunk address and extract the right tag. */
1324 #define mem2chunk(mem) ((mchunkptr)tag_at (((char*)(mem) - CHUNK_HDR_SZ)))
1326 /* The smallest possible chunk */
1327 #define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
1329 /* The smallest size we can malloc is an aligned minimal chunk */
1332 (unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
1334 /* Check if m has acceptable alignment */
1336 #define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
1338 #define misaligned_chunk(p) \
1339 ((uintptr_t)(MALLOC_ALIGNMENT == CHUNK_HDR_SZ ? (p) : chunk2mem (p)) \
1340 & MALLOC_ALIGN_MASK)
1342 /* pad request bytes into a usable size -- internal version */
1343 /* Note: This must be a macro that evaluates to a compile time constant
1344 if passed a literal constant. */
1345 #define request2size(req) \
1346 (((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
1348 ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
1350 /* Check if REQ overflows when padded and aligned and if the resulting value
1351 is less than PTRDIFF_T. Returns TRUE and the requested size or MINSIZE in
1352 case the value is less than MINSIZE on SZ or false if any of the previous
1355 checked_request2size (size_t req
, size_t *sz
) __nonnull (1)
1357 if (__glibc_unlikely (req
> PTRDIFF_MAX
))
1360 /* When using tagged memory, we cannot share the end of the user
1361 block with the header for the next chunk, so ensure that we
1362 allocate blocks that are rounded up to the granule size. Take
1363 care not to overflow from close to MAX_SIZE_T to a small
1364 number. Ideally, this would be part of request2size(), but that
1365 must be a macro that produces a compile time constant if passed
1366 a constant literal. */
1367 if (__glibc_unlikely (mtag_enabled
))
1369 /* Ensure this is not evaluated if !mtag_enabled, see gcc PR 99551. */
1372 req
= (req
+ (__MTAG_GRANULE_SIZE
- 1)) &
1373 ~(size_t)(__MTAG_GRANULE_SIZE
- 1);
1376 *sz
= request2size (req
);
1381 --------------- Physical chunk operations ---------------
1385 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1386 #define PREV_INUSE 0x1
1388 /* extract inuse bit of previous chunk */
1389 #define prev_inuse(p) ((p)->mchunk_size & PREV_INUSE)
1392 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1393 #define IS_MMAPPED 0x2
1395 /* check for mmap()'ed chunk */
1396 #define chunk_is_mmapped(p) ((p)->mchunk_size & IS_MMAPPED)
1399 /* size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
1400 from a non-main arena. This is only set immediately before handing
1401 the chunk to the user, if necessary. */
1402 #define NON_MAIN_ARENA 0x4
1404 /* Check for chunk from main arena. */
1405 #define chunk_main_arena(p) (((p)->mchunk_size & NON_MAIN_ARENA) == 0)
1407 /* Mark a chunk as not being on the main arena. */
1408 #define set_non_main_arena(p) ((p)->mchunk_size |= NON_MAIN_ARENA)
1412 Bits to mask off when extracting size
1414 Note: IS_MMAPPED is intentionally not masked off from size field in
1415 macros for which mmapped chunks should never be seen. This should
1416 cause helpful core dumps to occur if it is tried by accident by
1417 people extending or adapting this malloc.
1419 #define SIZE_BITS (PREV_INUSE | IS_MMAPPED | NON_MAIN_ARENA)
1421 /* Get size, ignoring use bits */
1422 #define chunksize(p) (chunksize_nomask (p) & ~(SIZE_BITS))
1424 /* Like chunksize, but do not mask SIZE_BITS. */
1425 #define chunksize_nomask(p) ((p)->mchunk_size)
1427 /* Ptr to next physical malloc_chunk. */
1428 #define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
1430 /* Size of the chunk below P. Only valid if !prev_inuse (P). */
1431 #define prev_size(p) ((p)->mchunk_prev_size)
1433 /* Set the size of the chunk below P. Only valid if !prev_inuse (P). */
1434 #define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
1436 /* Ptr to previous physical malloc_chunk. Only valid if !prev_inuse (P). */
1437 #define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
1439 /* Treat space at ptr + offset as a chunk */
1440 #define chunk_at_offset(p, s) ((mchunkptr) (((char *) (p)) + (s)))
1442 /* extract p's inuse bit */
1444 ((((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size) & PREV_INUSE)
1446 /* set/clear chunk as being inuse without otherwise disturbing */
1447 #define set_inuse(p) \
1448 ((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size |= PREV_INUSE
1450 #define clear_inuse(p) \
1451 ((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size &= ~(PREV_INUSE)
1454 /* check/set/clear inuse bits in known places */
1455 #define inuse_bit_at_offset(p, s) \
1456 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size & PREV_INUSE)
1458 #define set_inuse_bit_at_offset(p, s) \
1459 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size |= PREV_INUSE)
1461 #define clear_inuse_bit_at_offset(p, s) \
1462 (((mchunkptr) (((char *) (p)) + (s)))->mchunk_size &= ~(PREV_INUSE))
1465 /* Set size at head, without disturbing its use bit */
1466 #define set_head_size(p, s) ((p)->mchunk_size = (((p)->mchunk_size & SIZE_BITS) | (s)))
1468 /* Set size/use field */
1469 #define set_head(p, s) ((p)->mchunk_size = (s))
1471 /* Set size at footer (only when chunk is not in use) */
1472 #define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s))
1474 #pragma GCC poison mchunk_size
1475 #pragma GCC poison mchunk_prev_size
1477 /* This is the size of the real usable data in the chunk. Not valid for
1478 dumped heap chunks. */
1479 #define memsize(p) \
1480 (__MTAG_GRANULE_SIZE > SIZE_SZ && __glibc_unlikely (mtag_enabled) ? \
1481 chunksize (p) - CHUNK_HDR_SZ : \
1482 chunksize (p) - CHUNK_HDR_SZ + (chunk_is_mmapped (p) ? 0 : SIZE_SZ))
1484 /* If memory tagging is enabled the layout changes to accommodate the granule
1485 size, this is wasteful for small allocations so not done by default.
1486 Both the chunk header and user data has to be granule aligned. */
1487 _Static_assert (__MTAG_GRANULE_SIZE
<= CHUNK_HDR_SZ
,
1488 "memory tagging is not supported with large granule.");
1490 static __always_inline
void *
1491 tag_new_usable (void *ptr
)
1493 if (__glibc_unlikely (mtag_enabled
) && ptr
)
1495 mchunkptr cp
= mem2chunk(ptr
);
1496 ptr
= __libc_mtag_tag_region (__libc_mtag_new_tag (ptr
), memsize (cp
));
1502 -------------------- Internal data structures --------------------
1504 All internal state is held in an instance of malloc_state defined
1505 below. There are no other static variables, except in two optional
1507 * If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
1508 * If mmap doesn't support MAP_ANONYMOUS, a dummy file descriptor
1511 Beware of lots of tricks that minimize the total bookkeeping space
1512 requirements. The result is a little over 1K bytes (for 4byte
1513 pointers and size_t.)
1519 An array of bin headers for free chunks. Each bin is doubly
1520 linked. The bins are approximately proportionally (log) spaced.
1521 There are a lot of these bins (128). This may look excessive, but
1522 works very well in practice. Most bins hold sizes that are
1523 unusual as malloc request sizes, but are more usual for fragments
1524 and consolidated sets of chunks, which is what these bins hold, so
1525 they can be found quickly. All procedures maintain the invariant
1526 that no consolidated chunk physically borders another one, so each
1527 chunk in a list is known to be preceeded and followed by either
1528 inuse chunks or the ends of memory.
1530 Chunks in bins are kept in size order, with ties going to the
1531 approximately least recently used chunk. Ordering isn't needed
1532 for the small bins, which all contain the same-sized chunks, but
1533 facilitates best-fit allocation for larger chunks. These lists
1534 are just sequential. Keeping them in order almost never requires
1535 enough traversal to warrant using fancier ordered data
1538 Chunks of the same size are linked with the most
1539 recently freed at the front, and allocations are taken from the
1540 back. This results in LRU (FIFO) allocation order, which tends
1541 to give each chunk an equal opportunity to be consolidated with
1542 adjacent freed chunks, resulting in larger free chunks and less
1545 To simplify use in double-linked lists, each bin header acts
1546 as a malloc_chunk. This avoids special-casing for headers.
1547 But to conserve space and improve locality, we allocate
1548 only the fd/bk pointers of bins, and then use repositioning tricks
1549 to treat these as the fields of a malloc_chunk*.
1552 typedef struct malloc_chunk
*mbinptr
;
1554 /* addressing -- note that bin_at(0) does not exist */
1555 #define bin_at(m, i) \
1556 (mbinptr) (((char *) &((m)->bins[((i) - 1) * 2])) \
1557 - offsetof (struct malloc_chunk, fd))
1559 /* analog of ++bin */
1560 #define next_bin(b) ((mbinptr) ((char *) (b) + (sizeof (mchunkptr) << 1)))
1562 /* Reminders about list directionality within bins */
1563 #define first(b) ((b)->fd)
1564 #define last(b) ((b)->bk)
1569 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1570 8 bytes apart. Larger bins are approximately logarithmically spaced:
1576 4 bins of size 32768
1577 2 bins of size 262144
1578 1 bin of size what's left
1580 There is actually a little bit of slop in the numbers in bin_index
1581 for the sake of speed. This makes no difference elsewhere.
1583 The bins top out around 1MB because we expect to service large
1586 Bin 0 does not exist. Bin 1 is the unordered list; if that would be
1587 a valid chunk size the small bins are bumped up one.
1591 #define NSMALLBINS 64
1592 #define SMALLBIN_WIDTH MALLOC_ALIGNMENT
1593 #define SMALLBIN_CORRECTION (MALLOC_ALIGNMENT > CHUNK_HDR_SZ)
1594 #define MIN_LARGE_SIZE ((NSMALLBINS - SMALLBIN_CORRECTION) * SMALLBIN_WIDTH)
1596 #define in_smallbin_range(sz) \
1597 ((unsigned long) (sz) < (unsigned long) MIN_LARGE_SIZE)
1599 #define smallbin_index(sz) \
1600 ((SMALLBIN_WIDTH == 16 ? (((unsigned) (sz)) >> 4) : (((unsigned) (sz)) >> 3))\
1601 + SMALLBIN_CORRECTION)
1603 #define largebin_index_32(sz) \
1604 (((((unsigned long) (sz)) >> 6) <= 38) ? 56 + (((unsigned long) (sz)) >> 6) :\
1605 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1606 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1607 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1608 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1611 #define largebin_index_32_big(sz) \
1612 (((((unsigned long) (sz)) >> 6) <= 45) ? 49 + (((unsigned long) (sz)) >> 6) :\
1613 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1614 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1615 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1616 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1619 // XXX It remains to be seen whether it is good to keep the widths of
1620 // XXX the buckets the same or whether it should be scaled by a factor
1621 // XXX of two as well.
1622 #define largebin_index_64(sz) \
1623 (((((unsigned long) (sz)) >> 6) <= 48) ? 48 + (((unsigned long) (sz)) >> 6) :\
1624 ((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1625 ((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1626 ((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1627 ((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1630 #define largebin_index(sz) \
1631 (SIZE_SZ == 8 ? largebin_index_64 (sz) \
1632 : MALLOC_ALIGNMENT == 16 ? largebin_index_32_big (sz) \
1633 : largebin_index_32 (sz))
1635 #define bin_index(sz) \
1636 ((in_smallbin_range (sz)) ? smallbin_index (sz) : largebin_index (sz))
1638 /* Take a chunk off a bin list. */
1640 unlink_chunk (mstate av
, mchunkptr p
)
1642 if (chunksize (p
) != prev_size (next_chunk (p
)))
1643 malloc_printerr ("corrupted size vs. prev_size");
1645 mchunkptr fd
= p
->fd
;
1646 mchunkptr bk
= p
->bk
;
1648 if (__builtin_expect (fd
->bk
!= p
|| bk
->fd
!= p
, 0))
1649 malloc_printerr ("corrupted double-linked list");
1653 if (!in_smallbin_range (chunksize_nomask (p
)) && p
->fd_nextsize
!= NULL
)
1655 if (p
->fd_nextsize
->bk_nextsize
!= p
1656 || p
->bk_nextsize
->fd_nextsize
!= p
)
1657 malloc_printerr ("corrupted double-linked list (not small)");
1659 if (fd
->fd_nextsize
== NULL
)
1661 if (p
->fd_nextsize
== p
)
1662 fd
->fd_nextsize
= fd
->bk_nextsize
= fd
;
1665 fd
->fd_nextsize
= p
->fd_nextsize
;
1666 fd
->bk_nextsize
= p
->bk_nextsize
;
1667 p
->fd_nextsize
->bk_nextsize
= fd
;
1668 p
->bk_nextsize
->fd_nextsize
= fd
;
1673 p
->fd_nextsize
->bk_nextsize
= p
->bk_nextsize
;
1674 p
->bk_nextsize
->fd_nextsize
= p
->fd_nextsize
;
1682 All remainders from chunk splits, as well as all returned chunks,
1683 are first placed in the "unsorted" bin. They are then placed
1684 in regular bins after malloc gives them ONE chance to be used before
1685 binning. So, basically, the unsorted_chunks list acts as a queue,
1686 with chunks being placed on it in free (and malloc_consolidate),
1687 and taken off (to be either used or placed in bins) in malloc.
1689 The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
1690 does not have to be taken into account in size comparisons.
1693 /* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
1694 #define unsorted_chunks(M) (bin_at (M, 1))
1699 The top-most available chunk (i.e., the one bordering the end of
1700 available memory) is treated specially. It is never included in
1701 any bin, is used only if no other chunk is available, and is
1702 released back to the system if it is very large (see
1703 M_TRIM_THRESHOLD). Because top initially
1704 points to its own bin with initial zero size, thus forcing
1705 extension on the first malloc request, we avoid having any special
1706 code in malloc to check whether it even exists yet. But we still
1707 need to do so when getting memory from system, so we make
1708 initial_top treat the bin as a legal but unusable chunk during the
1709 interval between initialization and the first call to
1710 sysmalloc. (This is somewhat delicate, since it relies on
1711 the 2 preceding words to be zero during this interval as well.)
1714 /* Conveniently, the unsorted bin can be used as dummy top on first call */
1715 #define initial_top(M) (unsorted_chunks (M))
1720 To help compensate for the large number of bins, a one-level index
1721 structure is used for bin-by-bin searching. `binmap' is a
1722 bitvector recording whether bins are definitely empty so they can
1723 be skipped over during during traversals. The bits are NOT always
1724 cleared as soon as bins are empty, but instead only
1725 when they are noticed to be empty during traversal in malloc.
1728 /* Conservatively use 32 bits per map word, even if on 64bit system */
1729 #define BINMAPSHIFT 5
1730 #define BITSPERMAP (1U << BINMAPSHIFT)
1731 #define BINMAPSIZE (NBINS / BITSPERMAP)
1733 #define idx2block(i) ((i) >> BINMAPSHIFT)
1734 #define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT) - 1))))
1736 #define mark_bin(m, i) ((m)->binmap[idx2block (i)] |= idx2bit (i))
1737 #define unmark_bin(m, i) ((m)->binmap[idx2block (i)] &= ~(idx2bit (i)))
1738 #define get_binmap(m, i) ((m)->binmap[idx2block (i)] & idx2bit (i))
1743 An array of lists holding recently freed small chunks. Fastbins
1744 are not doubly linked. It is faster to single-link them, and
1745 since chunks are never removed from the middles of these lists,
1746 double linking is not necessary. Also, unlike regular bins, they
1747 are not even processed in FIFO order (they use faster LIFO) since
1748 ordering doesn't much matter in the transient contexts in which
1749 fastbins are normally used.
1751 Chunks in fastbins keep their inuse bit set, so they cannot
1752 be consolidated with other free chunks. malloc_consolidate
1753 releases all chunks in fastbins and consolidates them with
1757 typedef struct malloc_chunk
*mfastbinptr
;
1758 #define fastbin(ar_ptr, idx) ((ar_ptr)->fastbinsY[idx])
1760 /* offset 2 to use otherwise unindexable first 2 bins */
1761 #define fastbin_index(sz) \
1762 ((((unsigned int) (sz)) >> (SIZE_SZ == 8 ? 4 : 3)) - 2)
1765 /* The maximum fastbin request size we support */
1766 #define MAX_FAST_SIZE (80 * SIZE_SZ / 4)
1768 #define NFASTBINS (fastbin_index (request2size (MAX_FAST_SIZE)) + 1)
1771 FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
1772 that triggers automatic consolidation of possibly-surrounding
1773 fastbin chunks. This is a heuristic, so the exact value should not
1774 matter too much. It is defined at half the default trim threshold as a
1775 compromise heuristic to only attempt consolidation if it is likely
1776 to lead to trimming. However, it is not dynamically tunable, since
1777 consolidation reduces fragmentation surrounding large chunks even
1778 if trimming is not used.
1781 #define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
1784 NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
1785 regions. Otherwise, contiguity is exploited in merging together,
1786 when possible, results from consecutive MORECORE calls.
1788 The initial value comes from MORECORE_CONTIGUOUS, but is
1789 changed dynamically if mmap is ever used as an sbrk substitute.
1792 #define NONCONTIGUOUS_BIT (2U)
1794 #define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
1795 #define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
1796 #define set_noncontiguous(M) ((M)->flags |= NONCONTIGUOUS_BIT)
1797 #define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
1799 /* Maximum size of memory handled in fastbins. */
1800 static INTERNAL_SIZE_T global_max_fast
;
1803 Set value of max_fast.
1804 Use impossibly small value if 0.
1805 Precondition: there are no existing fastbin chunks in the main arena.
1806 Since do_check_malloc_state () checks this, we call malloc_consolidate ()
1807 before changing max_fast. Note other arenas will leak their fast bin
1808 entries if max_fast is reduced.
1811 #define set_max_fast(s) \
1812 global_max_fast = (((size_t) (s) <= MALLOC_ALIGN_MASK - SIZE_SZ) \
1813 ? MIN_CHUNK_SIZE / 2 : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
1815 static inline INTERNAL_SIZE_T
1818 /* Tell the GCC optimizers that global_max_fast is never larger
1819 than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in
1820 _int_malloc after constant propagation of the size parameter.
1821 (The code never executes because malloc preserves the
1822 global_max_fast invariant, but the optimizers may not recognize
1824 if (global_max_fast
> MAX_FAST_SIZE
)
1825 __builtin_unreachable ();
1826 return global_max_fast
;
1830 ----------- Internal state representation and initialization -----------
1834 have_fastchunks indicates that there are probably some fastbin chunks.
1835 It is set true on entering a chunk into any fastbin, and cleared early in
1836 malloc_consolidate. The value is approximate since it may be set when there
1837 are no fastbin chunks, or it may be clear even if there are fastbin chunks
1838 available. Given it's sole purpose is to reduce number of redundant calls to
1839 malloc_consolidate, it does not affect correctness. As a result we can safely
1840 use relaxed atomic accesses.
1846 /* Serialize access. */
1847 __libc_lock_define (, mutex
);
1849 /* Flags (formerly in max_fast). */
1852 /* Set if the fastbin chunks contain recently inserted free blocks. */
1853 /* Note this is a bool but not all targets support atomics on booleans. */
1854 int have_fastchunks
;
1857 mfastbinptr fastbinsY
[NFASTBINS
];
1859 /* Base of the topmost chunk -- not otherwise kept in a bin */
1862 /* The remainder from the most recent split of a small request */
1863 mchunkptr last_remainder
;
1865 /* Normal bins packed as described above */
1866 mchunkptr bins
[NBINS
* 2 - 2];
1868 /* Bitmap of bins */
1869 unsigned int binmap
[BINMAPSIZE
];
1872 struct malloc_state
*next
;
1874 /* Linked list for free arenas. Access to this field is serialized
1875 by free_list_lock in arena.c. */
1876 struct malloc_state
*next_free
;
1878 /* Number of threads attached to this arena. 0 if the arena is on
1879 the free list. Access to this field is serialized by
1880 free_list_lock in arena.c. */
1881 INTERNAL_SIZE_T attached_threads
;
1883 /* Memory allocated from the system in this arena. */
1884 INTERNAL_SIZE_T system_mem
;
1885 INTERNAL_SIZE_T max_system_mem
;
1890 /* Tunable parameters */
1891 unsigned long trim_threshold
;
1892 INTERNAL_SIZE_T top_pad
;
1893 INTERNAL_SIZE_T mmap_threshold
;
1894 INTERNAL_SIZE_T arena_test
;
1895 INTERNAL_SIZE_T arena_max
;
1897 /* Memory map support */
1901 /* the mmap_threshold is dynamic, until the user sets
1902 it manually, at which point we need to disable any
1903 dynamic behavior. */
1904 int no_dyn_threshold
;
1907 INTERNAL_SIZE_T mmapped_mem
;
1908 INTERNAL_SIZE_T max_mmapped_mem
;
1910 /* First address handed out by MORECORE/sbrk. */
1914 /* Maximum number of buckets to use. */
1916 size_t tcache_max_bytes
;
1917 /* Maximum number of chunks in each bucket. */
1918 size_t tcache_count
;
1919 /* Maximum number of chunks to remove from the unsorted list, which
1920 aren't used to prefill the cache. */
1921 size_t tcache_unsorted_limit
;
1925 /* There are several instances of this struct ("arenas") in this
1926 malloc. If you are adapting this malloc in a way that does NOT use
1927 a static or mmapped malloc_state, you MUST explicitly zero-fill it
1928 before using. This malloc relies on the property that malloc_state
1929 is initialized to all zeroes (as is true of C statics). */
1931 static struct malloc_state main_arena
=
1933 .mutex
= _LIBC_LOCK_INITIALIZER
,
1934 .next
= &main_arena
,
1935 .attached_threads
= 1
1938 /* These variables are used for undumping support. Chunked are marked
1939 as using mmap, but we leave them alone if they fall into this
1940 range. NB: The chunk size for these chunks only includes the
1941 initial size field (of SIZE_SZ bytes), there is no trailing size
1942 field (unlike with regular mmapped chunks). */
1943 static mchunkptr dumped_main_arena_start
; /* Inclusive. */
1944 static mchunkptr dumped_main_arena_end
; /* Exclusive. */
1946 /* True if the pointer falls into the dumped arena. Use this after
1947 chunk_is_mmapped indicates a chunk is mmapped. */
1948 #define DUMPED_MAIN_ARENA_CHUNK(p) \
1949 ((p) >= dumped_main_arena_start && (p) < dumped_main_arena_end)
1951 /* There is only one instance of the malloc parameters. */
1953 static struct malloc_par mp_
=
1955 .top_pad
= DEFAULT_TOP_PAD
,
1956 .n_mmaps_max
= DEFAULT_MMAP_MAX
,
1957 .mmap_threshold
= DEFAULT_MMAP_THRESHOLD
,
1958 .trim_threshold
= DEFAULT_TRIM_THRESHOLD
,
1959 #define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8))
1960 .arena_test
= NARENAS_FROM_NCORES (1)
1963 .tcache_count
= TCACHE_FILL_COUNT
,
1964 .tcache_bins
= TCACHE_MAX_BINS
,
1965 .tcache_max_bytes
= tidx2usize (TCACHE_MAX_BINS
-1),
1966 .tcache_unsorted_limit
= 0 /* No limit. */
1971 Initialize a malloc_state struct.
1973 This is called from ptmalloc_init () or from _int_new_arena ()
1974 when creating a new arena.
1978 malloc_init_state (mstate av
)
1983 /* Establish circular links for normal bins */
1984 for (i
= 1; i
< NBINS
; ++i
)
1986 bin
= bin_at (av
, i
);
1987 bin
->fd
= bin
->bk
= bin
;
1990 #if MORECORE_CONTIGUOUS
1991 if (av
!= &main_arena
)
1993 set_noncontiguous (av
);
1994 if (av
== &main_arena
)
1995 set_max_fast (DEFAULT_MXFAST
);
1996 atomic_store_relaxed (&av
->have_fastchunks
, false);
1998 av
->top
= initial_top (av
);
2002 Other internal utilities operating on mstates
2005 static void *sysmalloc (INTERNAL_SIZE_T
, mstate
);
2006 static int systrim (size_t, mstate
);
2007 static void malloc_consolidate (mstate
);
2010 /* -------------- Early definitions for debugging hooks ---------------- */
2012 /* Define and initialize the hook variables. These weak definitions must
2013 appear before any use of the variables in a function (arena.c uses one). */
2014 #ifndef weak_variable
2015 /* In GNU libc we want the hook variables to be weak definitions to
2016 avoid a problem with Emacs. */
2017 # define weak_variable weak_function
2020 /* Forward declarations. */
2021 static void *malloc_hook_ini (size_t sz
,
2022 const void *caller
) __THROW
;
2023 static void *realloc_hook_ini (void *ptr
, size_t sz
,
2024 const void *caller
) __THROW
;
2025 static void *memalign_hook_ini (size_t alignment
, size_t sz
,
2026 const void *caller
) __THROW
;
2028 #if HAVE_MALLOC_INIT_HOOK
2029 void (*__malloc_initialize_hook
) (void);
2030 compat_symbol (libc
, __malloc_initialize_hook
,
2031 __malloc_initialize_hook
, GLIBC_2_0
);
2034 void weak_variable (*__free_hook
) (void *__ptr
,
2035 const void *) = NULL
;
2036 void *weak_variable (*__malloc_hook
)
2037 (size_t __size
, const void *) = malloc_hook_ini
;
2038 void *weak_variable (*__realloc_hook
)
2039 (void *__ptr
, size_t __size
, const void *)
2041 void *weak_variable (*__memalign_hook
)
2042 (size_t __alignment
, size_t __size
, const void *)
2043 = memalign_hook_ini
;
2044 void weak_variable (*__after_morecore_hook
) (void) = NULL
;
2046 /* This function is called from the arena shutdown hook, to free the
2047 thread cache (if it exists). */
2048 static void tcache_thread_shutdown (void);
2050 /* ------------------ Testing support ----------------------------------*/
2052 static int perturb_byte
;
2055 alloc_perturb (char *p
, size_t n
)
2057 if (__glibc_unlikely (perturb_byte
))
2058 memset (p
, perturb_byte
^ 0xff, n
);
2062 free_perturb (char *p
, size_t n
)
2064 if (__glibc_unlikely (perturb_byte
))
2065 memset (p
, perturb_byte
, n
);
2070 #include <stap-probe.h>
2072 /* ------------------- Support for multiple arenas -------------------- */
2078 These routines make a number of assertions about the states
2079 of data structures that should be true at all times. If any
2080 are not true, it's very likely that a user program has somehow
2081 trashed memory. (It's also possible that there is a coding error
2082 in malloc. In which case, please report it!)
2087 # define check_chunk(A, P)
2088 # define check_free_chunk(A, P)
2089 # define check_inuse_chunk(A, P)
2090 # define check_remalloced_chunk(A, P, N)
2091 # define check_malloced_chunk(A, P, N)
2092 # define check_malloc_state(A)
2096 # define check_chunk(A, P) do_check_chunk (A, P)
2097 # define check_free_chunk(A, P) do_check_free_chunk (A, P)
2098 # define check_inuse_chunk(A, P) do_check_inuse_chunk (A, P)
2099 # define check_remalloced_chunk(A, P, N) do_check_remalloced_chunk (A, P, N)
2100 # define check_malloced_chunk(A, P, N) do_check_malloced_chunk (A, P, N)
2101 # define check_malloc_state(A) do_check_malloc_state (A)
2104 Properties of all chunks
2108 do_check_chunk (mstate av
, mchunkptr p
)
2110 unsigned long sz
= chunksize (p
);
2111 /* min and max possible addresses assuming contiguous allocation */
2112 char *max_address
= (char *) (av
->top
) + chunksize (av
->top
);
2113 char *min_address
= max_address
- av
->system_mem
;
2115 if (!chunk_is_mmapped (p
))
2117 /* Has legal address ... */
2120 if (contiguous (av
))
2122 assert (((char *) p
) >= min_address
);
2123 assert (((char *) p
+ sz
) <= ((char *) (av
->top
)));
2128 /* top size is always at least MINSIZE */
2129 assert ((unsigned long) (sz
) >= MINSIZE
);
2130 /* top predecessor always marked inuse */
2131 assert (prev_inuse (p
));
2134 else if (!DUMPED_MAIN_ARENA_CHUNK (p
))
2136 /* address is outside main heap */
2137 if (contiguous (av
) && av
->top
!= initial_top (av
))
2139 assert (((char *) p
) < min_address
|| ((char *) p
) >= max_address
);
2141 /* chunk is page-aligned */
2142 assert (((prev_size (p
) + sz
) & (GLRO (dl_pagesize
) - 1)) == 0);
2143 /* mem is aligned */
2144 assert (aligned_OK (chunk2mem (p
)));
2149 Properties of free chunks
2153 do_check_free_chunk (mstate av
, mchunkptr p
)
2155 INTERNAL_SIZE_T sz
= chunksize_nomask (p
) & ~(PREV_INUSE
| NON_MAIN_ARENA
);
2156 mchunkptr next
= chunk_at_offset (p
, sz
);
2158 do_check_chunk (av
, p
);
2160 /* Chunk must claim to be free ... */
2161 assert (!inuse (p
));
2162 assert (!chunk_is_mmapped (p
));
2164 /* Unless a special marker, must have OK fields */
2165 if ((unsigned long) (sz
) >= MINSIZE
)
2167 assert ((sz
& MALLOC_ALIGN_MASK
) == 0);
2168 assert (aligned_OK (chunk2mem (p
)));
2169 /* ... matching footer field */
2170 assert (prev_size (next_chunk (p
)) == sz
);
2171 /* ... and is fully consolidated */
2172 assert (prev_inuse (p
));
2173 assert (next
== av
->top
|| inuse (next
));
2175 /* ... and has minimally sane links */
2176 assert (p
->fd
->bk
== p
);
2177 assert (p
->bk
->fd
== p
);
2179 else /* markers are always of size SIZE_SZ */
2180 assert (sz
== SIZE_SZ
);
2184 Properties of inuse chunks
2188 do_check_inuse_chunk (mstate av
, mchunkptr p
)
2192 do_check_chunk (av
, p
);
2194 if (chunk_is_mmapped (p
))
2195 return; /* mmapped chunks have no next/prev */
2197 /* Check whether it claims to be in use ... */
2200 next
= next_chunk (p
);
2202 /* ... and is surrounded by OK chunks.
2203 Since more things can be checked with free chunks than inuse ones,
2204 if an inuse chunk borders them and debug is on, it's worth doing them.
2206 if (!prev_inuse (p
))
2208 /* Note that we cannot even look at prev unless it is not inuse */
2209 mchunkptr prv
= prev_chunk (p
);
2210 assert (next_chunk (prv
) == p
);
2211 do_check_free_chunk (av
, prv
);
2214 if (next
== av
->top
)
2216 assert (prev_inuse (next
));
2217 assert (chunksize (next
) >= MINSIZE
);
2219 else if (!inuse (next
))
2220 do_check_free_chunk (av
, next
);
2224 Properties of chunks recycled from fastbins
2228 do_check_remalloced_chunk (mstate av
, mchunkptr p
, INTERNAL_SIZE_T s
)
2230 INTERNAL_SIZE_T sz
= chunksize_nomask (p
) & ~(PREV_INUSE
| NON_MAIN_ARENA
);
2232 if (!chunk_is_mmapped (p
))
2234 assert (av
== arena_for_chunk (p
));
2235 if (chunk_main_arena (p
))
2236 assert (av
== &main_arena
);
2238 assert (av
!= &main_arena
);
2241 do_check_inuse_chunk (av
, p
);
2243 /* Legal size ... */
2244 assert ((sz
& MALLOC_ALIGN_MASK
) == 0);
2245 assert ((unsigned long) (sz
) >= MINSIZE
);
2246 /* ... and alignment */
2247 assert (aligned_OK (chunk2mem (p
)));
2248 /* chunk is less than MINSIZE more than request */
2249 assert ((long) (sz
) - (long) (s
) >= 0);
2250 assert ((long) (sz
) - (long) (s
+ MINSIZE
) < 0);
2254 Properties of nonrecycled chunks at the point they are malloced
2258 do_check_malloced_chunk (mstate av
, mchunkptr p
, INTERNAL_SIZE_T s
)
2260 /* same as recycled case ... */
2261 do_check_remalloced_chunk (av
, p
, s
);
2264 ... plus, must obey implementation invariant that prev_inuse is
2265 always true of any allocated chunk; i.e., that each allocated
2266 chunk borders either a previously allocated and still in-use
2267 chunk, or the base of its memory arena. This is ensured
2268 by making all allocations from the `lowest' part of any found
2269 chunk. This does not necessarily hold however for chunks
2270 recycled via fastbins.
2273 assert (prev_inuse (p
));
2278 Properties of malloc_state.
2280 This may be useful for debugging malloc, as well as detecting user
2281 programmer errors that somehow write into malloc_state.
2283 If you are extending or experimenting with this malloc, you can
2284 probably figure out how to hack this routine to print out or
2285 display chunk addresses, sizes, bins, and other instrumentation.
2289 do_check_malloc_state (mstate av
)
2296 INTERNAL_SIZE_T size
;
2297 unsigned long total
= 0;
2300 /* internal size_t must be no wider than pointer type */
2301 assert (sizeof (INTERNAL_SIZE_T
) <= sizeof (char *));
2303 /* alignment is a power of 2 */
2304 assert ((MALLOC_ALIGNMENT
& (MALLOC_ALIGNMENT
- 1)) == 0);
2306 /* Check the arena is initialized. */
2307 assert (av
->top
!= 0);
2309 /* No memory has been allocated yet, so doing more tests is not possible. */
2310 if (av
->top
== initial_top (av
))
2313 /* pagesize is a power of 2 */
2314 assert (powerof2(GLRO (dl_pagesize
)));
2316 /* A contiguous main_arena is consistent with sbrk_base. */
2317 if (av
== &main_arena
&& contiguous (av
))
2318 assert ((char *) mp_
.sbrk_base
+ av
->system_mem
==
2319 (char *) av
->top
+ chunksize (av
->top
));
2321 /* properties of fastbins */
2323 /* max_fast is in allowed range */
2324 assert ((get_max_fast () & ~1) <= request2size (MAX_FAST_SIZE
));
2326 max_fast_bin
= fastbin_index (get_max_fast ());
2328 for (i
= 0; i
< NFASTBINS
; ++i
)
2330 p
= fastbin (av
, i
);
2332 /* The following test can only be performed for the main arena.
2333 While mallopt calls malloc_consolidate to get rid of all fast
2334 bins (especially those larger than the new maximum) this does
2335 only happen for the main arena. Trying to do this for any
2336 other arena would mean those arenas have to be locked and
2337 malloc_consolidate be called for them. This is excessive. And
2338 even if this is acceptable to somebody it still cannot solve
2339 the problem completely since if the arena is locked a
2340 concurrent malloc call might create a new arena which then
2341 could use the newly invalid fast bins. */
2343 /* all bins past max_fast are empty */
2344 if (av
== &main_arena
&& i
> max_fast_bin
)
2349 if (__glibc_unlikely (misaligned_chunk (p
)))
2350 malloc_printerr ("do_check_malloc_state(): "
2351 "unaligned fastbin chunk detected");
2352 /* each chunk claims to be inuse */
2353 do_check_inuse_chunk (av
, p
);
2354 total
+= chunksize (p
);
2355 /* chunk belongs in this bin */
2356 assert (fastbin_index (chunksize (p
)) == i
);
2357 p
= REVEAL_PTR (p
->fd
);
2361 /* check normal bins */
2362 for (i
= 1; i
< NBINS
; ++i
)
2366 /* binmap is accurate (except for bin 1 == unsorted_chunks) */
2369 unsigned int binbit
= get_binmap (av
, i
);
2370 int empty
= last (b
) == b
;
2377 for (p
= last (b
); p
!= b
; p
= p
->bk
)
2379 /* each chunk claims to be free */
2380 do_check_free_chunk (av
, p
);
2381 size
= chunksize (p
);
2385 /* chunk belongs in bin */
2386 idx
= bin_index (size
);
2388 /* lists are sorted */
2389 assert (p
->bk
== b
||
2390 (unsigned long) chunksize (p
->bk
) >= (unsigned long) chunksize (p
));
2392 if (!in_smallbin_range (size
))
2394 if (p
->fd_nextsize
!= NULL
)
2396 if (p
->fd_nextsize
== p
)
2397 assert (p
->bk_nextsize
== p
);
2400 if (p
->fd_nextsize
== first (b
))
2401 assert (chunksize (p
) < chunksize (p
->fd_nextsize
));
2403 assert (chunksize (p
) > chunksize (p
->fd_nextsize
));
2406 assert (chunksize (p
) > chunksize (p
->bk_nextsize
));
2408 assert (chunksize (p
) < chunksize (p
->bk_nextsize
));
2412 assert (p
->bk_nextsize
== NULL
);
2415 else if (!in_smallbin_range (size
))
2416 assert (p
->fd_nextsize
== NULL
&& p
->bk_nextsize
== NULL
);
2417 /* chunk is followed by a legal chain of inuse chunks */
2418 for (q
= next_chunk (p
);
2419 (q
!= av
->top
&& inuse (q
) &&
2420 (unsigned long) (chunksize (q
)) >= MINSIZE
);
2422 do_check_inuse_chunk (av
, q
);
2426 /* top chunk is OK */
2427 check_chunk (av
, av
->top
);
2432 /* ----------------- Support for debugging hooks -------------------- */
2436 /* ----------- Routines dealing with system allocation -------------- */
2439 sysmalloc handles malloc cases requiring more memory from the system.
2440 On entry, it is assumed that av->top does not have enough
2441 space to service request for nb bytes, thus requiring that av->top
2442 be extended or replaced.
2446 sysmalloc (INTERNAL_SIZE_T nb
, mstate av
)
2448 mchunkptr old_top
; /* incoming value of av->top */
2449 INTERNAL_SIZE_T old_size
; /* its size */
2450 char *old_end
; /* its end address */
2452 long size
; /* arg to first MORECORE or mmap call */
2453 char *brk
; /* return value from MORECORE */
2455 long correction
; /* arg to 2nd MORECORE call */
2456 char *snd_brk
; /* 2nd return val */
2458 INTERNAL_SIZE_T front_misalign
; /* unusable bytes at front of new space */
2459 INTERNAL_SIZE_T end_misalign
; /* partial page left at end of new space */
2460 char *aligned_brk
; /* aligned offset into brk */
2462 mchunkptr p
; /* the allocated/returned chunk */
2463 mchunkptr remainder
; /* remainder from allocation */
2464 unsigned long remainder_size
; /* its size */
2467 size_t pagesize
= GLRO (dl_pagesize
);
2468 bool tried_mmap
= false;
2472 If have mmap, and the request size meets the mmap threshold, and
2473 the system supports mmap, and there are few enough currently
2474 allocated mmapped regions, try to directly map this request
2475 rather than expanding top.
2479 || ((unsigned long) (nb
) >= (unsigned long) (mp_
.mmap_threshold
)
2480 && (mp_
.n_mmaps
< mp_
.n_mmaps_max
)))
2482 char *mm
; /* return value from mmap call*/
2486 Round up size to nearest page. For mmapped chunks, the overhead
2487 is one SIZE_SZ unit larger than for normal chunks, because there
2488 is no following chunk whose prev_size field could be used.
2490 See the front_misalign handling below, for glibc there is no
2491 need for further alignments unless we have have high alignment.
2493 if (MALLOC_ALIGNMENT
== CHUNK_HDR_SZ
)
2494 size
= ALIGN_UP (nb
+ SIZE_SZ
, pagesize
);
2496 size
= ALIGN_UP (nb
+ SIZE_SZ
+ MALLOC_ALIGN_MASK
, pagesize
);
2499 /* Don't try if size wraps around 0 */
2500 if ((unsigned long) (size
) > (unsigned long) (nb
))
2502 mm
= (char *) (MMAP (0, size
,
2503 mtag_mmap_flags
| PROT_READ
| PROT_WRITE
, 0));
2505 if (mm
!= MAP_FAILED
)
2508 The offset to the start of the mmapped region is stored
2509 in the prev_size field of the chunk. This allows us to adjust
2510 returned start address to meet alignment requirements here
2511 and in memalign(), and still be able to compute proper
2512 address argument for later munmap in free() and realloc().
2515 if (MALLOC_ALIGNMENT
== CHUNK_HDR_SZ
)
2517 /* For glibc, chunk2mem increases the address by
2518 CHUNK_HDR_SZ and MALLOC_ALIGN_MASK is
2519 CHUNK_HDR_SZ-1. Each mmap'ed area is page
2520 aligned and therefore definitely
2521 MALLOC_ALIGN_MASK-aligned. */
2522 assert (((INTERNAL_SIZE_T
) chunk2mem (mm
) & MALLOC_ALIGN_MASK
) == 0);
2526 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (mm
) & MALLOC_ALIGN_MASK
;
2527 if (front_misalign
> 0)
2529 correction
= MALLOC_ALIGNMENT
- front_misalign
;
2530 p
= (mchunkptr
) (mm
+ correction
);
2531 set_prev_size (p
, correction
);
2532 set_head (p
, (size
- correction
) | IS_MMAPPED
);
2537 set_prev_size (p
, 0);
2538 set_head (p
, size
| IS_MMAPPED
);
2541 /* update statistics */
2543 int new = atomic_exchange_and_add (&mp_
.n_mmaps
, 1) + 1;
2544 atomic_max (&mp_
.max_n_mmaps
, new);
2547 sum
= atomic_exchange_and_add (&mp_
.mmapped_mem
, size
) + size
;
2548 atomic_max (&mp_
.max_mmapped_mem
, sum
);
2550 check_chunk (av
, p
);
2552 return chunk2mem (p
);
2557 /* There are no usable arenas and mmap also failed. */
2561 /* Record incoming configuration of top */
2564 old_size
= chunksize (old_top
);
2565 old_end
= (char *) (chunk_at_offset (old_top
, old_size
));
2567 brk
= snd_brk
= (char *) (MORECORE_FAILURE
);
2570 If not the first time through, we require old_size to be
2571 at least MINSIZE and to have prev_inuse set.
2574 assert ((old_top
== initial_top (av
) && old_size
== 0) ||
2575 ((unsigned long) (old_size
) >= MINSIZE
&&
2576 prev_inuse (old_top
) &&
2577 ((unsigned long) old_end
& (pagesize
- 1)) == 0));
2579 /* Precondition: not enough current space to satisfy nb request */
2580 assert ((unsigned long) (old_size
) < (unsigned long) (nb
+ MINSIZE
));
2583 if (av
!= &main_arena
)
2585 heap_info
*old_heap
, *heap
;
2586 size_t old_heap_size
;
2588 /* First try to extend the current heap. */
2589 old_heap
= heap_for_ptr (old_top
);
2590 old_heap_size
= old_heap
->size
;
2591 if ((long) (MINSIZE
+ nb
- old_size
) > 0
2592 && grow_heap (old_heap
, MINSIZE
+ nb
- old_size
) == 0)
2594 av
->system_mem
+= old_heap
->size
- old_heap_size
;
2595 set_head (old_top
, (((char *) old_heap
+ old_heap
->size
) - (char *) old_top
)
2598 else if ((heap
= new_heap (nb
+ (MINSIZE
+ sizeof (*heap
)), mp_
.top_pad
)))
2600 /* Use a newly allocated heap. */
2602 heap
->prev
= old_heap
;
2603 av
->system_mem
+= heap
->size
;
2604 /* Set up the new top. */
2605 top (av
) = chunk_at_offset (heap
, sizeof (*heap
));
2606 set_head (top (av
), (heap
->size
- sizeof (*heap
)) | PREV_INUSE
);
2608 /* Setup fencepost and free the old top chunk with a multiple of
2609 MALLOC_ALIGNMENT in size. */
2610 /* The fencepost takes at least MINSIZE bytes, because it might
2611 become the top chunk again later. Note that a footer is set
2612 up, too, although the chunk is marked in use. */
2613 old_size
= (old_size
- MINSIZE
) & ~MALLOC_ALIGN_MASK
;
2614 set_head (chunk_at_offset (old_top
, old_size
+ CHUNK_HDR_SZ
),
2616 if (old_size
>= MINSIZE
)
2618 set_head (chunk_at_offset (old_top
, old_size
),
2619 CHUNK_HDR_SZ
| PREV_INUSE
);
2620 set_foot (chunk_at_offset (old_top
, old_size
), CHUNK_HDR_SZ
);
2621 set_head (old_top
, old_size
| PREV_INUSE
| NON_MAIN_ARENA
);
2622 _int_free (av
, old_top
, 1);
2626 set_head (old_top
, (old_size
+ CHUNK_HDR_SZ
) | PREV_INUSE
);
2627 set_foot (old_top
, (old_size
+ CHUNK_HDR_SZ
));
2630 else if (!tried_mmap
)
2631 /* We can at least try to use to mmap memory. */
2634 else /* av == main_arena */
2637 { /* Request enough space for nb + pad + overhead */
2638 size
= nb
+ mp_
.top_pad
+ MINSIZE
;
2641 If contiguous, we can subtract out existing space that we hope to
2642 combine with new space. We add it back later only if
2643 we don't actually get contiguous space.
2646 if (contiguous (av
))
2650 Round to a multiple of page size.
2651 If MORECORE is not contiguous, this ensures that we only call it
2652 with whole-page arguments. And if MORECORE is contiguous and
2653 this is not first time through, this preserves page-alignment of
2654 previous calls. Otherwise, we correct to page-align below.
2657 size
= ALIGN_UP (size
, pagesize
);
2660 Don't try to call MORECORE if argument is so big as to appear
2661 negative. Note that since mmap takes size_t arg, it may succeed
2662 below even if we cannot call MORECORE.
2667 brk
= (char *) (MORECORE (size
));
2668 LIBC_PROBE (memory_sbrk_more
, 2, brk
, size
);
2671 if (brk
!= (char *) (MORECORE_FAILURE
))
2673 /* Call the `morecore' hook if necessary. */
2674 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2675 if (__builtin_expect (hook
!= NULL
, 0))
2681 If have mmap, try using it as a backup when MORECORE fails or
2682 cannot be used. This is worth doing on systems that have "holes" in
2683 address space, so sbrk cannot extend to give contiguous space, but
2684 space is available elsewhere. Note that we ignore mmap max count
2685 and threshold limits, since the space will not be used as a
2686 segregated mmap region.
2689 /* Cannot merge with old top, so add its size back in */
2690 if (contiguous (av
))
2691 size
= ALIGN_UP (size
+ old_size
, pagesize
);
2693 /* If we are relying on mmap as backup, then use larger units */
2694 if ((unsigned long) (size
) < (unsigned long) (MMAP_AS_MORECORE_SIZE
))
2695 size
= MMAP_AS_MORECORE_SIZE
;
2697 /* Don't try if size wraps around 0 */
2698 if ((unsigned long) (size
) > (unsigned long) (nb
))
2700 char *mbrk
= (char *) (MMAP (0, size
,
2701 mtag_mmap_flags
| PROT_READ
| PROT_WRITE
,
2704 if (mbrk
!= MAP_FAILED
)
2706 /* We do not need, and cannot use, another sbrk call to find end */
2708 snd_brk
= brk
+ size
;
2711 Record that we no longer have a contiguous sbrk region.
2712 After the first time mmap is used as backup, we do not
2713 ever rely on contiguous space since this could incorrectly
2716 set_noncontiguous (av
);
2721 if (brk
!= (char *) (MORECORE_FAILURE
))
2723 if (mp_
.sbrk_base
== 0)
2724 mp_
.sbrk_base
= brk
;
2725 av
->system_mem
+= size
;
2728 If MORECORE extends previous space, we can likewise extend top size.
2731 if (brk
== old_end
&& snd_brk
== (char *) (MORECORE_FAILURE
))
2732 set_head (old_top
, (size
+ old_size
) | PREV_INUSE
);
2734 else if (contiguous (av
) && old_size
&& brk
< old_end
)
2735 /* Oops! Someone else killed our space.. Can't touch anything. */
2736 malloc_printerr ("break adjusted to free malloc space");
2739 Otherwise, make adjustments:
2741 * If the first time through or noncontiguous, we need to call sbrk
2742 just to find out where the end of memory lies.
2744 * We need to ensure that all returned chunks from malloc will meet
2747 * If there was an intervening foreign sbrk, we need to adjust sbrk
2748 request size to account for fact that we will not be able to
2749 combine new space with existing space in old_top.
2751 * Almost all systems internally allocate whole pages at a time, in
2752 which case we might as well use the whole last page of request.
2753 So we allocate enough more memory to hit a page boundary now,
2754 which in turn causes future contiguous calls to page-align.
2764 /* handle contiguous cases */
2765 if (contiguous (av
))
2767 /* Count foreign sbrk as system_mem. */
2769 av
->system_mem
+= brk
- old_end
;
2771 /* Guarantee alignment of first new chunk made from this space */
2773 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (brk
) & MALLOC_ALIGN_MASK
;
2774 if (front_misalign
> 0)
2777 Skip over some bytes to arrive at an aligned position.
2778 We don't need to specially mark these wasted front bytes.
2779 They will never be accessed anyway because
2780 prev_inuse of av->top (and any chunk created from its start)
2781 is always true after initialization.
2784 correction
= MALLOC_ALIGNMENT
- front_misalign
;
2785 aligned_brk
+= correction
;
2789 If this isn't adjacent to existing space, then we will not
2790 be able to merge with old_top space, so must add to 2nd request.
2793 correction
+= old_size
;
2795 /* Extend the end address to hit a page boundary */
2796 end_misalign
= (INTERNAL_SIZE_T
) (brk
+ size
+ correction
);
2797 correction
+= (ALIGN_UP (end_misalign
, pagesize
)) - end_misalign
;
2799 assert (correction
>= 0);
2800 snd_brk
= (char *) (MORECORE (correction
));
2803 If can't allocate correction, try to at least find out current
2804 brk. It might be enough to proceed without failing.
2806 Note that if second sbrk did NOT fail, we assume that space
2807 is contiguous with first sbrk. This is a safe assumption unless
2808 program is multithreaded but doesn't use locks and a foreign sbrk
2809 occurred between our first and second calls.
2812 if (snd_brk
== (char *) (MORECORE_FAILURE
))
2815 snd_brk
= (char *) (MORECORE (0));
2819 /* Call the `morecore' hook if necessary. */
2820 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2821 if (__builtin_expect (hook
!= NULL
, 0))
2826 /* handle non-contiguous cases */
2829 if (MALLOC_ALIGNMENT
== CHUNK_HDR_SZ
)
2830 /* MORECORE/mmap must correctly align */
2831 assert (((unsigned long) chunk2mem (brk
) & MALLOC_ALIGN_MASK
) == 0);
2834 front_misalign
= (INTERNAL_SIZE_T
) chunk2mem (brk
) & MALLOC_ALIGN_MASK
;
2835 if (front_misalign
> 0)
2838 Skip over some bytes to arrive at an aligned position.
2839 We don't need to specially mark these wasted front bytes.
2840 They will never be accessed anyway because
2841 prev_inuse of av->top (and any chunk created from its start)
2842 is always true after initialization.
2845 aligned_brk
+= MALLOC_ALIGNMENT
- front_misalign
;
2849 /* Find out current end of memory */
2850 if (snd_brk
== (char *) (MORECORE_FAILURE
))
2852 snd_brk
= (char *) (MORECORE (0));
2856 /* Adjust top based on results of second sbrk */
2857 if (snd_brk
!= (char *) (MORECORE_FAILURE
))
2859 av
->top
= (mchunkptr
) aligned_brk
;
2860 set_head (av
->top
, (snd_brk
- aligned_brk
+ correction
) | PREV_INUSE
);
2861 av
->system_mem
+= correction
;
2864 If not the first time through, we either have a
2865 gap due to foreign sbrk or a non-contiguous region. Insert a
2866 double fencepost at old_top to prevent consolidation with space
2867 we don't own. These fenceposts are artificial chunks that are
2868 marked as inuse and are in any case too small to use. We need
2869 two to make sizes and alignments work out.
2875 Shrink old_top to insert fenceposts, keeping size a
2876 multiple of MALLOC_ALIGNMENT. We know there is at least
2877 enough space in old_top to do this.
2879 old_size
= (old_size
- 2 * CHUNK_HDR_SZ
) & ~MALLOC_ALIGN_MASK
;
2880 set_head (old_top
, old_size
| PREV_INUSE
);
2883 Note that the following assignments completely overwrite
2884 old_top when old_size was previously MINSIZE. This is
2885 intentional. We need the fencepost, even if old_top otherwise gets
2888 set_head (chunk_at_offset (old_top
, old_size
),
2889 CHUNK_HDR_SZ
| PREV_INUSE
);
2890 set_head (chunk_at_offset (old_top
,
2891 old_size
+ CHUNK_HDR_SZ
),
2892 CHUNK_HDR_SZ
| PREV_INUSE
);
2894 /* If possible, release the rest. */
2895 if (old_size
>= MINSIZE
)
2897 _int_free (av
, old_top
, 1);
2903 } /* if (av != &main_arena) */
2905 if ((unsigned long) av
->system_mem
> (unsigned long) (av
->max_system_mem
))
2906 av
->max_system_mem
= av
->system_mem
;
2907 check_malloc_state (av
);
2909 /* finally, do the allocation */
2911 size
= chunksize (p
);
2913 /* check that one of the above allocation paths succeeded */
2914 if ((unsigned long) (size
) >= (unsigned long) (nb
+ MINSIZE
))
2916 remainder_size
= size
- nb
;
2917 remainder
= chunk_at_offset (p
, nb
);
2918 av
->top
= remainder
;
2919 set_head (p
, nb
| PREV_INUSE
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
2920 set_head (remainder
, remainder_size
| PREV_INUSE
);
2921 check_malloced_chunk (av
, p
, nb
);
2922 return chunk2mem (p
);
2925 /* catch all failure paths */
2926 __set_errno (ENOMEM
);
2932 systrim is an inverse of sorts to sysmalloc. It gives memory back
2933 to the system (via negative arguments to sbrk) if there is unused
2934 memory at the `high' end of the malloc pool. It is called
2935 automatically by free() when top space exceeds the trim
2936 threshold. It is also called by the public malloc_trim routine. It
2937 returns 1 if it actually released any memory, else 0.
2941 systrim (size_t pad
, mstate av
)
2943 long top_size
; /* Amount of top-most memory */
2944 long extra
; /* Amount to release */
2945 long released
; /* Amount actually released */
2946 char *current_brk
; /* address returned by pre-check sbrk call */
2947 char *new_brk
; /* address returned by post-check sbrk call */
2951 pagesize
= GLRO (dl_pagesize
);
2952 top_size
= chunksize (av
->top
);
2954 top_area
= top_size
- MINSIZE
- 1;
2955 if (top_area
<= pad
)
2958 /* Release in pagesize units and round down to the nearest page. */
2959 extra
= ALIGN_DOWN(top_area
- pad
, pagesize
);
2965 Only proceed if end of memory is where we last set it.
2966 This avoids problems if there were foreign sbrk calls.
2968 current_brk
= (char *) (MORECORE (0));
2969 if (current_brk
== (char *) (av
->top
) + top_size
)
2972 Attempt to release memory. We ignore MORECORE return value,
2973 and instead call again to find out where new end of memory is.
2974 This avoids problems if first call releases less than we asked,
2975 of if failure somehow altered brk value. (We could still
2976 encounter problems if it altered brk in some very bad way,
2977 but the only thing we can do is adjust anyway, which will cause
2978 some downstream failure.)
2982 /* Call the `morecore' hook if necessary. */
2983 void (*hook
) (void) = atomic_forced_read (__after_morecore_hook
);
2984 if (__builtin_expect (hook
!= NULL
, 0))
2986 new_brk
= (char *) (MORECORE (0));
2988 LIBC_PROBE (memory_sbrk_less
, 2, new_brk
, extra
);
2990 if (new_brk
!= (char *) MORECORE_FAILURE
)
2992 released
= (long) (current_brk
- new_brk
);
2996 /* Success. Adjust top. */
2997 av
->system_mem
-= released
;
2998 set_head (av
->top
, (top_size
- released
) | PREV_INUSE
);
2999 check_malloc_state (av
);
3008 munmap_chunk (mchunkptr p
)
3010 size_t pagesize
= GLRO (dl_pagesize
);
3011 INTERNAL_SIZE_T size
= chunksize (p
);
3013 assert (chunk_is_mmapped (p
));
3015 /* Do nothing if the chunk is a faked mmapped chunk in the dumped
3016 main arena. We never free this memory. */
3017 if (DUMPED_MAIN_ARENA_CHUNK (p
))
3020 uintptr_t mem
= (uintptr_t) chunk2mem (p
);
3021 uintptr_t block
= (uintptr_t) p
- prev_size (p
);
3022 size_t total_size
= prev_size (p
) + size
;
3023 /* Unfortunately we have to do the compilers job by hand here. Normally
3024 we would test BLOCK and TOTAL-SIZE separately for compliance with the
3025 page size. But gcc does not recognize the optimization possibility
3026 (in the moment at least) so we combine the two values into one before
3028 if (__glibc_unlikely ((block
| total_size
) & (pagesize
- 1)) != 0
3029 || __glibc_unlikely (!powerof2 (mem
& (pagesize
- 1))))
3030 malloc_printerr ("munmap_chunk(): invalid pointer");
3032 atomic_decrement (&mp_
.n_mmaps
);
3033 atomic_add (&mp_
.mmapped_mem
, -total_size
);
3035 /* If munmap failed the process virtual memory address space is in a
3036 bad shape. Just leave the block hanging around, the process will
3037 terminate shortly anyway since not much can be done. */
3038 __munmap ((char *) block
, total_size
);
3044 mremap_chunk (mchunkptr p
, size_t new_size
)
3046 size_t pagesize
= GLRO (dl_pagesize
);
3047 INTERNAL_SIZE_T offset
= prev_size (p
);
3048 INTERNAL_SIZE_T size
= chunksize (p
);
3051 assert (chunk_is_mmapped (p
));
3053 uintptr_t block
= (uintptr_t) p
- offset
;
3054 uintptr_t mem
= (uintptr_t) chunk2mem(p
);
3055 size_t total_size
= offset
+ size
;
3056 if (__glibc_unlikely ((block
| total_size
) & (pagesize
- 1)) != 0
3057 || __glibc_unlikely (!powerof2 (mem
& (pagesize
- 1))))
3058 malloc_printerr("mremap_chunk(): invalid pointer");
3060 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
3061 new_size
= ALIGN_UP (new_size
+ offset
+ SIZE_SZ
, pagesize
);
3063 /* No need to remap if the number of pages does not change. */
3064 if (total_size
== new_size
)
3067 cp
= (char *) __mremap ((char *) block
, total_size
, new_size
,
3070 if (cp
== MAP_FAILED
)
3073 p
= (mchunkptr
) (cp
+ offset
);
3075 assert (aligned_OK (chunk2mem (p
)));
3077 assert (prev_size (p
) == offset
);
3078 set_head (p
, (new_size
- offset
) | IS_MMAPPED
);
3080 INTERNAL_SIZE_T
new;
3081 new = atomic_exchange_and_add (&mp_
.mmapped_mem
, new_size
- size
- offset
)
3082 + new_size
- size
- offset
;
3083 atomic_max (&mp_
.max_mmapped_mem
, new);
3086 #endif /* HAVE_MREMAP */
3088 /*------------------------ Public wrappers. --------------------------------*/
3092 /* We overlay this structure on the user-data portion of a chunk when
3093 the chunk is stored in the per-thread cache. */
3094 typedef struct tcache_entry
3096 struct tcache_entry
*next
;
3097 /* This field exists to detect double frees. */
3101 /* There is one of these for each thread, which contains the
3102 per-thread cache (hence "tcache_perthread_struct"). Keeping
3103 overall size low is mildly important. Note that COUNTS and ENTRIES
3104 are redundant (we could have just counted the linked list each
3105 time), this is for performance reasons. */
3106 typedef struct tcache_perthread_struct
3108 uint16_t counts
[TCACHE_MAX_BINS
];
3109 tcache_entry
*entries
[TCACHE_MAX_BINS
];
3110 } tcache_perthread_struct
;
3112 static __thread
bool tcache_shutting_down
= false;
3113 static __thread tcache_perthread_struct
*tcache
= NULL
;
3115 /* Process-wide key to try and catch a double-free in the same thread. */
3116 static uintptr_t tcache_key
;
3118 /* The value of tcache_key does not really have to be a cryptographically
3119 secure random number. It only needs to be arbitrary enough so that it does
3120 not collide with values present in applications. If a collision does happen
3121 consistently enough, it could cause a degradation in performance since the
3122 entire list is checked to check if the block indeed has been freed the
3123 second time. The odds of this happening are exceedingly low though, about 1
3124 in 2^wordsize. There is probably a higher chance of the performance
3125 degradation being due to a double free where the first free happened in a
3126 different thread; that's a case this check does not cover. */
3128 tcache_key_initialize (void)
3130 if (__getrandom (&tcache_key
, sizeof(tcache_key
), GRND_NONBLOCK
)
3131 != sizeof (tcache_key
))
3133 tcache_key
= random_bits ();
3134 #if __WORDSIZE == 64
3135 tcache_key
= (tcache_key
<< 32) | random_bits ();
3140 /* Caller must ensure that we know tc_idx is valid and there's room
3142 static __always_inline
void
3143 tcache_put (mchunkptr chunk
, size_t tc_idx
)
3145 tcache_entry
*e
= (tcache_entry
*) chunk2mem (chunk
);
3147 /* Mark this chunk as "in the tcache" so the test in _int_free will
3148 detect a double free. */
3149 e
->key
= tcache_key
;
3151 e
->next
= PROTECT_PTR (&e
->next
, tcache
->entries
[tc_idx
]);
3152 tcache
->entries
[tc_idx
] = e
;
3153 ++(tcache
->counts
[tc_idx
]);
3156 /* Caller must ensure that we know tc_idx is valid and there's
3157 available chunks to remove. */
3158 static __always_inline
void *
3159 tcache_get (size_t tc_idx
)
3161 tcache_entry
*e
= tcache
->entries
[tc_idx
];
3162 if (__glibc_unlikely (!aligned_OK (e
)))
3163 malloc_printerr ("malloc(): unaligned tcache chunk detected");
3164 tcache
->entries
[tc_idx
] = REVEAL_PTR (e
->next
);
3165 --(tcache
->counts
[tc_idx
]);
3171 tcache_thread_shutdown (void)
3174 tcache_perthread_struct
*tcache_tmp
= tcache
;
3176 tcache_shutting_down
= true;
3181 /* Disable the tcache and prevent it from being reinitialized. */
3184 /* Free all of the entries and the tcache itself back to the arena
3185 heap for coalescing. */
3186 for (i
= 0; i
< TCACHE_MAX_BINS
; ++i
)
3188 while (tcache_tmp
->entries
[i
])
3190 tcache_entry
*e
= tcache_tmp
->entries
[i
];
3191 if (__glibc_unlikely (!aligned_OK (e
)))
3192 malloc_printerr ("tcache_thread_shutdown(): "
3193 "unaligned tcache chunk detected");
3194 tcache_tmp
->entries
[i
] = REVEAL_PTR (e
->next
);
3199 __libc_free (tcache_tmp
);
3207 const size_t bytes
= sizeof (tcache_perthread_struct
);
3209 if (tcache_shutting_down
)
3212 arena_get (ar_ptr
, bytes
);
3213 victim
= _int_malloc (ar_ptr
, bytes
);
3214 if (!victim
&& ar_ptr
!= NULL
)
3216 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
3217 victim
= _int_malloc (ar_ptr
, bytes
);
3222 __libc_lock_unlock (ar_ptr
->mutex
);
3224 /* In a low memory situation, we may not be able to allocate memory
3225 - in which case, we just keep trying later. However, we
3226 typically do this very early, so either there is sufficient
3227 memory, or there isn't enough memory to do non-trivial
3228 allocations anyway. */
3231 tcache
= (tcache_perthread_struct
*) victim
;
3232 memset (tcache
, 0, sizeof (tcache_perthread_struct
));
3237 # define MAYBE_INIT_TCACHE() \
3238 if (__glibc_unlikely (tcache == NULL)) \
3241 #else /* !USE_TCACHE */
3242 # define MAYBE_INIT_TCACHE()
3245 tcache_thread_shutdown (void)
3247 /* Nothing to do if there is no thread cache. */
3250 #endif /* !USE_TCACHE */
3253 __libc_malloc (size_t bytes
)
3258 _Static_assert (PTRDIFF_MAX
<= SIZE_MAX
/ 2,
3259 "PTRDIFF_MAX is not more than half of SIZE_MAX");
3261 void *(*hook
) (size_t, const void *)
3262 = atomic_forced_read (__malloc_hook
);
3263 if (__builtin_expect (hook
!= NULL
, 0))
3264 return (*hook
)(bytes
, RETURN_ADDRESS (0));
3266 /* int_free also calls request2size, be careful to not pad twice. */
3268 if (!checked_request2size (bytes
, &tbytes
))
3270 __set_errno (ENOMEM
);
3273 size_t tc_idx
= csize2tidx (tbytes
);
3275 MAYBE_INIT_TCACHE ();
3277 DIAG_PUSH_NEEDS_COMMENT
;
3278 if (tc_idx
< mp_
.tcache_bins
3280 && tcache
->counts
[tc_idx
] > 0)
3282 victim
= tcache_get (tc_idx
);
3283 return tag_new_usable (victim
);
3285 DIAG_POP_NEEDS_COMMENT
;
3288 if (SINGLE_THREAD_P
)
3290 victim
= tag_new_usable (_int_malloc (&main_arena
, bytes
));
3291 assert (!victim
|| chunk_is_mmapped (mem2chunk (victim
)) ||
3292 &main_arena
== arena_for_chunk (mem2chunk (victim
)));
3296 arena_get (ar_ptr
, bytes
);
3298 victim
= _int_malloc (ar_ptr
, bytes
);
3299 /* Retry with another arena only if we were able to find a usable arena
3301 if (!victim
&& ar_ptr
!= NULL
)
3303 LIBC_PROBE (memory_malloc_retry
, 1, bytes
);
3304 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
3305 victim
= _int_malloc (ar_ptr
, bytes
);
3309 __libc_lock_unlock (ar_ptr
->mutex
);
3311 victim
= tag_new_usable (victim
);
3313 assert (!victim
|| chunk_is_mmapped (mem2chunk (victim
)) ||
3314 ar_ptr
== arena_for_chunk (mem2chunk (victim
)));
3317 libc_hidden_def (__libc_malloc
)
3320 __libc_free (void *mem
)
3323 mchunkptr p
; /* chunk corresponding to mem */
3325 void (*hook
) (void *, const void *)
3326 = atomic_forced_read (__free_hook
);
3327 if (__builtin_expect (hook
!= NULL
, 0))
3329 (*hook
)(mem
, RETURN_ADDRESS (0));
3333 if (mem
== 0) /* free(0) has no effect */
3336 /* Quickly check that the freed pointer matches the tag for the memory.
3337 This gives a useful double-free detection. */
3338 if (__glibc_unlikely (mtag_enabled
))
3339 *(volatile char *)mem
;
3343 p
= mem2chunk (mem
);
3345 if (chunk_is_mmapped (p
)) /* release mmapped memory. */
3347 /* See if the dynamic brk/mmap threshold needs adjusting.
3348 Dumped fake mmapped chunks do not affect the threshold. */
3349 if (!mp_
.no_dyn_threshold
3350 && chunksize_nomask (p
) > mp_
.mmap_threshold
3351 && chunksize_nomask (p
) <= DEFAULT_MMAP_THRESHOLD_MAX
3352 && !DUMPED_MAIN_ARENA_CHUNK (p
))
3354 mp_
.mmap_threshold
= chunksize (p
);
3355 mp_
.trim_threshold
= 2 * mp_
.mmap_threshold
;
3356 LIBC_PROBE (memory_mallopt_free_dyn_thresholds
, 2,
3357 mp_
.mmap_threshold
, mp_
.trim_threshold
);
3363 MAYBE_INIT_TCACHE ();
3365 /* Mark the chunk as belonging to the library again. */
3366 (void)tag_region (chunk2mem (p
), memsize (p
));
3368 ar_ptr
= arena_for_chunk (p
);
3369 _int_free (ar_ptr
, p
, 0);
3374 libc_hidden_def (__libc_free
)
3377 __libc_realloc (void *oldmem
, size_t bytes
)
3380 INTERNAL_SIZE_T nb
; /* padded request size */
3382 void *newp
; /* chunk to return */
3384 void *(*hook
) (void *, size_t, const void *) =
3385 atomic_forced_read (__realloc_hook
);
3386 if (__builtin_expect (hook
!= NULL
, 0))
3387 return (*hook
)(oldmem
, bytes
, RETURN_ADDRESS (0));
3389 #if REALLOC_ZERO_BYTES_FREES
3390 if (bytes
== 0 && oldmem
!= NULL
)
3392 __libc_free (oldmem
); return 0;
3396 /* realloc of null is supposed to be same as malloc */
3398 return __libc_malloc (bytes
);
3400 /* Perform a quick check to ensure that the pointer's tag matches the
3402 if (__glibc_unlikely (mtag_enabled
))
3403 *(volatile char*) oldmem
;
3405 /* chunk corresponding to oldmem */
3406 const mchunkptr oldp
= mem2chunk (oldmem
);
3408 const INTERNAL_SIZE_T oldsize
= chunksize (oldp
);
3410 if (chunk_is_mmapped (oldp
))
3414 MAYBE_INIT_TCACHE ();
3415 ar_ptr
= arena_for_chunk (oldp
);
3418 /* Little security check which won't hurt performance: the allocator
3419 never wrapps around at the end of the address space. Therefore
3420 we can exclude some size values which might appear here by
3421 accident or by "design" from some intruder. We need to bypass
3422 this check for dumped fake mmap chunks from the old main arena
3423 because the new malloc may provide additional alignment. */
3424 if ((__builtin_expect ((uintptr_t) oldp
> (uintptr_t) -oldsize
, 0)
3425 || __builtin_expect (misaligned_chunk (oldp
), 0))
3426 && !DUMPED_MAIN_ARENA_CHUNK (oldp
))
3427 malloc_printerr ("realloc(): invalid pointer");
3429 if (!checked_request2size (bytes
, &nb
))
3431 __set_errno (ENOMEM
);
3435 if (chunk_is_mmapped (oldp
))
3437 /* If this is a faked mmapped chunk from the dumped main arena,
3438 always make a copy (and do not free the old chunk). */
3439 if (DUMPED_MAIN_ARENA_CHUNK (oldp
))
3441 /* Must alloc, copy, free. */
3442 void *newmem
= __libc_malloc (bytes
);
3445 /* Copy as many bytes as are available from the old chunk
3446 and fit into the new size. NB: The overhead for faked
3447 mmapped chunks is only SIZE_SZ, not CHUNK_HDR_SZ as for
3448 regular mmapped chunks. */
3449 if (bytes
> oldsize
- SIZE_SZ
)
3450 bytes
= oldsize
- SIZE_SZ
;
3451 memcpy (newmem
, oldmem
, bytes
);
3458 newp
= mremap_chunk (oldp
, nb
);
3461 void *newmem
= chunk2mem_tag (newp
);
3462 /* Give the new block a different tag. This helps to ensure
3463 that stale handles to the previous mapping are not
3464 reused. There's a performance hit for both us and the
3465 caller for doing this, so we might want to
3467 return tag_new_usable (newmem
);
3470 /* Note the extra SIZE_SZ overhead. */
3471 if (oldsize
- SIZE_SZ
>= nb
)
3472 return oldmem
; /* do nothing */
3474 /* Must alloc, copy, free. */
3475 newmem
= __libc_malloc (bytes
);
3477 return 0; /* propagate failure */
3479 memcpy (newmem
, oldmem
, oldsize
- CHUNK_HDR_SZ
);
3480 munmap_chunk (oldp
);
3484 if (SINGLE_THREAD_P
)
3486 newp
= _int_realloc (ar_ptr
, oldp
, oldsize
, nb
);
3487 assert (!newp
|| chunk_is_mmapped (mem2chunk (newp
)) ||
3488 ar_ptr
== arena_for_chunk (mem2chunk (newp
)));
3493 __libc_lock_lock (ar_ptr
->mutex
);
3495 newp
= _int_realloc (ar_ptr
, oldp
, oldsize
, nb
);
3497 __libc_lock_unlock (ar_ptr
->mutex
);
3498 assert (!newp
|| chunk_is_mmapped (mem2chunk (newp
)) ||
3499 ar_ptr
== arena_for_chunk (mem2chunk (newp
)));
3503 /* Try harder to allocate memory in other arenas. */
3504 LIBC_PROBE (memory_realloc_retry
, 2, bytes
, oldmem
);
3505 newp
= __libc_malloc (bytes
);
3508 size_t sz
= memsize (oldp
);
3509 memcpy (newp
, oldmem
, sz
);
3510 (void) tag_region (chunk2mem (oldp
), sz
);
3511 _int_free (ar_ptr
, oldp
, 0);
3517 libc_hidden_def (__libc_realloc
)
3520 __libc_memalign (size_t alignment
, size_t bytes
)
3522 void *address
= RETURN_ADDRESS (0);
3523 return _mid_memalign (alignment
, bytes
, address
);
3527 _mid_memalign (size_t alignment
, size_t bytes
, void *address
)
3532 void *(*hook
) (size_t, size_t, const void *) =
3533 atomic_forced_read (__memalign_hook
);
3534 if (__builtin_expect (hook
!= NULL
, 0))
3535 return (*hook
)(alignment
, bytes
, address
);
3537 /* If we need less alignment than we give anyway, just relay to malloc. */
3538 if (alignment
<= MALLOC_ALIGNMENT
)
3539 return __libc_malloc (bytes
);
3541 /* Otherwise, ensure that it is at least a minimum chunk size */
3542 if (alignment
< MINSIZE
)
3543 alignment
= MINSIZE
;
3545 /* If the alignment is greater than SIZE_MAX / 2 + 1 it cannot be a
3546 power of 2 and will cause overflow in the check below. */
3547 if (alignment
> SIZE_MAX
/ 2 + 1)
3549 __set_errno (EINVAL
);
3554 /* Make sure alignment is power of 2. */
3555 if (!powerof2 (alignment
))
3557 size_t a
= MALLOC_ALIGNMENT
* 2;
3558 while (a
< alignment
)
3563 if (SINGLE_THREAD_P
)
3565 p
= _int_memalign (&main_arena
, alignment
, bytes
);
3566 assert (!p
|| chunk_is_mmapped (mem2chunk (p
)) ||
3567 &main_arena
== arena_for_chunk (mem2chunk (p
)));
3568 return tag_new_usable (p
);
3571 arena_get (ar_ptr
, bytes
+ alignment
+ MINSIZE
);
3573 p
= _int_memalign (ar_ptr
, alignment
, bytes
);
3574 if (!p
&& ar_ptr
!= NULL
)
3576 LIBC_PROBE (memory_memalign_retry
, 2, bytes
, alignment
);
3577 ar_ptr
= arena_get_retry (ar_ptr
, bytes
);
3578 p
= _int_memalign (ar_ptr
, alignment
, bytes
);
3582 __libc_lock_unlock (ar_ptr
->mutex
);
3584 assert (!p
|| chunk_is_mmapped (mem2chunk (p
)) ||
3585 ar_ptr
== arena_for_chunk (mem2chunk (p
)));
3586 return tag_new_usable (p
);
3589 weak_alias (__libc_memalign
, aligned_alloc
)
3590 libc_hidden_def (__libc_memalign
)
3593 __libc_valloc (size_t bytes
)
3595 if (__malloc_initialized
< 0)
3598 void *address
= RETURN_ADDRESS (0);
3599 size_t pagesize
= GLRO (dl_pagesize
);
3600 return _mid_memalign (pagesize
, bytes
, address
);
3604 __libc_pvalloc (size_t bytes
)
3606 if (__malloc_initialized
< 0)
3609 void *address
= RETURN_ADDRESS (0);
3610 size_t pagesize
= GLRO (dl_pagesize
);
3611 size_t rounded_bytes
;
3612 /* ALIGN_UP with overflow check. */
3613 if (__glibc_unlikely (__builtin_add_overflow (bytes
,
3617 __set_errno (ENOMEM
);
3620 rounded_bytes
= rounded_bytes
& -(pagesize
- 1);
3622 return _mid_memalign (pagesize
, rounded_bytes
, address
);
3626 __libc_calloc (size_t n
, size_t elem_size
)
3630 INTERNAL_SIZE_T sz
, oldtopsize
;
3632 unsigned long clearsize
;
3633 unsigned long nclears
;
3637 if (__glibc_unlikely (__builtin_mul_overflow (n
, elem_size
, &bytes
)))
3639 __set_errno (ENOMEM
);
3645 void *(*hook
) (size_t, const void *) =
3646 atomic_forced_read (__malloc_hook
);
3647 if (__builtin_expect (hook
!= NULL
, 0))
3649 mem
= (*hook
)(sz
, RETURN_ADDRESS (0));
3653 return memset (mem
, 0, sz
);
3656 MAYBE_INIT_TCACHE ();
3658 if (SINGLE_THREAD_P
)
3665 /* Check if we hand out the top chunk, in which case there may be no
3669 oldtopsize
= chunksize (top (av
));
3670 # if MORECORE_CLEARS < 2
3671 /* Only newly allocated memory is guaranteed to be cleared. */
3672 if (av
== &main_arena
&&
3673 oldtopsize
< mp_
.sbrk_base
+ av
->max_system_mem
- (char *) oldtop
)
3674 oldtopsize
= (mp_
.sbrk_base
+ av
->max_system_mem
- (char *) oldtop
);
3676 if (av
!= &main_arena
)
3678 heap_info
*heap
= heap_for_ptr (oldtop
);
3679 if (oldtopsize
< (char *) heap
+ heap
->mprotect_size
- (char *) oldtop
)
3680 oldtopsize
= (char *) heap
+ heap
->mprotect_size
- (char *) oldtop
;
3686 /* No usable arenas. */
3690 mem
= _int_malloc (av
, sz
);
3692 assert (!mem
|| chunk_is_mmapped (mem2chunk (mem
)) ||
3693 av
== arena_for_chunk (mem2chunk (mem
)));
3695 if (!SINGLE_THREAD_P
)
3697 if (mem
== 0 && av
!= NULL
)
3699 LIBC_PROBE (memory_calloc_retry
, 1, sz
);
3700 av
= arena_get_retry (av
, sz
);
3701 mem
= _int_malloc (av
, sz
);
3705 __libc_lock_unlock (av
->mutex
);
3708 /* Allocation failed even after a retry. */
3712 mchunkptr p
= mem2chunk (mem
);
3714 /* If we are using memory tagging, then we need to set the tags
3715 regardless of MORECORE_CLEARS, so we zero the whole block while
3717 if (__glibc_unlikely (mtag_enabled
))
3718 return tag_new_zero_region (mem
, memsize (p
));
3720 INTERNAL_SIZE_T csz
= chunksize (p
);
3722 /* Two optional cases in which clearing not necessary */
3723 if (chunk_is_mmapped (p
))
3725 if (__builtin_expect (perturb_byte
, 0))
3726 return memset (mem
, 0, sz
);
3732 if (perturb_byte
== 0 && (p
== oldtop
&& csz
> oldtopsize
))
3734 /* clear only the bytes from non-freshly-sbrked memory */
3739 /* Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that
3740 contents have an odd number of INTERNAL_SIZE_T-sized words;
3742 d
= (INTERNAL_SIZE_T
*) mem
;
3743 clearsize
= csz
- SIZE_SZ
;
3744 nclears
= clearsize
/ sizeof (INTERNAL_SIZE_T
);
3745 assert (nclears
>= 3);
3748 return memset (d
, 0, clearsize
);
3776 ------------------------------ malloc ------------------------------
3780 _int_malloc (mstate av
, size_t bytes
)
3782 INTERNAL_SIZE_T nb
; /* normalized request size */
3783 unsigned int idx
; /* associated bin index */
3784 mbinptr bin
; /* associated bin */
3786 mchunkptr victim
; /* inspected/selected chunk */
3787 INTERNAL_SIZE_T size
; /* its size */
3788 int victim_index
; /* its bin index */
3790 mchunkptr remainder
; /* remainder from a split */
3791 unsigned long remainder_size
; /* its size */
3793 unsigned int block
; /* bit map traverser */
3794 unsigned int bit
; /* bit map traverser */
3795 unsigned int map
; /* current word of binmap */
3797 mchunkptr fwd
; /* misc temp for linking */
3798 mchunkptr bck
; /* misc temp for linking */
3801 size_t tcache_unsorted_count
; /* count of unsorted chunks processed */
3805 Convert request size to internal form by adding SIZE_SZ bytes
3806 overhead plus possibly more to obtain necessary alignment and/or
3807 to obtain a size of at least MINSIZE, the smallest allocatable
3808 size. Also, checked_request2size returns false for request sizes
3809 that are so large that they wrap around zero when padded and
3813 if (!checked_request2size (bytes
, &nb
))
3815 __set_errno (ENOMEM
);
3819 /* There are no usable arenas. Fall back to sysmalloc to get a chunk from
3821 if (__glibc_unlikely (av
== NULL
))
3823 void *p
= sysmalloc (nb
, av
);
3825 alloc_perturb (p
, bytes
);
3830 If the size qualifies as a fastbin, first check corresponding bin.
3831 This code is safe to execute even if av is not yet initialized, so we
3832 can try it without checking, which saves some time on this fast path.
3835 #define REMOVE_FB(fb, victim, pp) \
3839 if (victim == NULL) \
3841 pp = REVEAL_PTR (victim->fd); \
3842 if (__glibc_unlikely (pp != NULL && misaligned_chunk (pp))) \
3843 malloc_printerr ("malloc(): unaligned fastbin chunk detected"); \
3845 while ((pp = catomic_compare_and_exchange_val_acq (fb, pp, victim)) \
3848 if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ()))
3850 idx
= fastbin_index (nb
);
3851 mfastbinptr
*fb
= &fastbin (av
, idx
);
3857 if (__glibc_unlikely (misaligned_chunk (victim
)))
3858 malloc_printerr ("malloc(): unaligned fastbin chunk detected 2");
3860 if (SINGLE_THREAD_P
)
3861 *fb
= REVEAL_PTR (victim
->fd
);
3863 REMOVE_FB (fb
, pp
, victim
);
3864 if (__glibc_likely (victim
!= NULL
))
3866 size_t victim_idx
= fastbin_index (chunksize (victim
));
3867 if (__builtin_expect (victim_idx
!= idx
, 0))
3868 malloc_printerr ("malloc(): memory corruption (fast)");
3869 check_remalloced_chunk (av
, victim
, nb
);
3871 /* While we're here, if we see other chunks of the same size,
3872 stash them in the tcache. */
3873 size_t tc_idx
= csize2tidx (nb
);
3874 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3876 mchunkptr tc_victim
;
3878 /* While bin not empty and tcache not full, copy chunks. */
3879 while (tcache
->counts
[tc_idx
] < mp_
.tcache_count
3880 && (tc_victim
= *fb
) != NULL
)
3882 if (__glibc_unlikely (misaligned_chunk (tc_victim
)))
3883 malloc_printerr ("malloc(): unaligned fastbin chunk detected 3");
3884 if (SINGLE_THREAD_P
)
3885 *fb
= REVEAL_PTR (tc_victim
->fd
);
3888 REMOVE_FB (fb
, pp
, tc_victim
);
3889 if (__glibc_unlikely (tc_victim
== NULL
))
3892 tcache_put (tc_victim
, tc_idx
);
3896 void *p
= chunk2mem (victim
);
3897 alloc_perturb (p
, bytes
);
3904 If a small request, check regular bin. Since these "smallbins"
3905 hold one size each, no searching within bins is necessary.
3906 (For a large request, we need to wait until unsorted chunks are
3907 processed to find best fit. But for small ones, fits are exact
3908 anyway, so we can check now, which is faster.)
3911 if (in_smallbin_range (nb
))
3913 idx
= smallbin_index (nb
);
3914 bin
= bin_at (av
, idx
);
3916 if ((victim
= last (bin
)) != bin
)
3919 if (__glibc_unlikely (bck
->fd
!= victim
))
3920 malloc_printerr ("malloc(): smallbin double linked list corrupted");
3921 set_inuse_bit_at_offset (victim
, nb
);
3925 if (av
!= &main_arena
)
3926 set_non_main_arena (victim
);
3927 check_malloced_chunk (av
, victim
, nb
);
3929 /* While we're here, if we see other chunks of the same size,
3930 stash them in the tcache. */
3931 size_t tc_idx
= csize2tidx (nb
);
3932 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3934 mchunkptr tc_victim
;
3936 /* While bin not empty and tcache not full, copy chunks over. */
3937 while (tcache
->counts
[tc_idx
] < mp_
.tcache_count
3938 && (tc_victim
= last (bin
)) != bin
)
3942 bck
= tc_victim
->bk
;
3943 set_inuse_bit_at_offset (tc_victim
, nb
);
3944 if (av
!= &main_arena
)
3945 set_non_main_arena (tc_victim
);
3949 tcache_put (tc_victim
, tc_idx
);
3954 void *p
= chunk2mem (victim
);
3955 alloc_perturb (p
, bytes
);
3961 If this is a large request, consolidate fastbins before continuing.
3962 While it might look excessive to kill all fastbins before
3963 even seeing if there is space available, this avoids
3964 fragmentation problems normally associated with fastbins.
3965 Also, in practice, programs tend to have runs of either small or
3966 large requests, but less often mixtures, so consolidation is not
3967 invoked all that often in most programs. And the programs that
3968 it is called frequently in otherwise tend to fragment.
3973 idx
= largebin_index (nb
);
3974 if (atomic_load_relaxed (&av
->have_fastchunks
))
3975 malloc_consolidate (av
);
3979 Process recently freed or remaindered chunks, taking one only if
3980 it is exact fit, or, if this a small request, the chunk is remainder from
3981 the most recent non-exact fit. Place other traversed chunks in
3982 bins. Note that this step is the only place in any routine where
3983 chunks are placed in bins.
3985 The outer loop here is needed because we might not realize until
3986 near the end of malloc that we should have consolidated, so must
3987 do so and retry. This happens at most once, and only when we would
3988 otherwise need to expand memory to service a "small" request.
3992 INTERNAL_SIZE_T tcache_nb
= 0;
3993 size_t tc_idx
= csize2tidx (nb
);
3994 if (tcache
&& tc_idx
< mp_
.tcache_bins
)
3996 int return_cached
= 0;
3998 tcache_unsorted_count
= 0;
4004 while ((victim
= unsorted_chunks (av
)->bk
) != unsorted_chunks (av
))
4007 size
= chunksize (victim
);
4008 mchunkptr next
= chunk_at_offset (victim
, size
);
4010 if (__glibc_unlikely (size
<= CHUNK_HDR_SZ
)
4011 || __glibc_unlikely (size
> av
->system_mem
))
4012 malloc_printerr ("malloc(): invalid size (unsorted)");
4013 if (__glibc_unlikely (chunksize_nomask (next
) < CHUNK_HDR_SZ
)
4014 || __glibc_unlikely (chunksize_nomask (next
) > av
->system_mem
))
4015 malloc_printerr ("malloc(): invalid next size (unsorted)");
4016 if (__glibc_unlikely ((prev_size (next
) & ~(SIZE_BITS
)) != size
))
4017 malloc_printerr ("malloc(): mismatching next->prev_size (unsorted)");
4018 if (__glibc_unlikely (bck
->fd
!= victim
)
4019 || __glibc_unlikely (victim
->fd
!= unsorted_chunks (av
)))
4020 malloc_printerr ("malloc(): unsorted double linked list corrupted");
4021 if (__glibc_unlikely (prev_inuse (next
)))
4022 malloc_printerr ("malloc(): invalid next->prev_inuse (unsorted)");
4025 If a small request, try to use last remainder if it is the
4026 only chunk in unsorted bin. This helps promote locality for
4027 runs of consecutive small requests. This is the only
4028 exception to best-fit, and applies only when there is
4029 no exact fit for a small chunk.
4032 if (in_smallbin_range (nb
) &&
4033 bck
== unsorted_chunks (av
) &&
4034 victim
== av
->last_remainder
&&
4035 (unsigned long) (size
) > (unsigned long) (nb
+ MINSIZE
))
4037 /* split and reattach remainder */
4038 remainder_size
= size
- nb
;
4039 remainder
= chunk_at_offset (victim
, nb
);
4040 unsorted_chunks (av
)->bk
= unsorted_chunks (av
)->fd
= remainder
;
4041 av
->last_remainder
= remainder
;
4042 remainder
->bk
= remainder
->fd
= unsorted_chunks (av
);
4043 if (!in_smallbin_range (remainder_size
))
4045 remainder
->fd_nextsize
= NULL
;
4046 remainder
->bk_nextsize
= NULL
;
4049 set_head (victim
, nb
| PREV_INUSE
|
4050 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4051 set_head (remainder
, remainder_size
| PREV_INUSE
);
4052 set_foot (remainder
, remainder_size
);
4054 check_malloced_chunk (av
, victim
, nb
);
4055 void *p
= chunk2mem (victim
);
4056 alloc_perturb (p
, bytes
);
4060 /* remove from unsorted list */
4061 if (__glibc_unlikely (bck
->fd
!= victim
))
4062 malloc_printerr ("malloc(): corrupted unsorted chunks 3");
4063 unsorted_chunks (av
)->bk
= bck
;
4064 bck
->fd
= unsorted_chunks (av
);
4066 /* Take now instead of binning if exact fit */
4070 set_inuse_bit_at_offset (victim
, size
);
4071 if (av
!= &main_arena
)
4072 set_non_main_arena (victim
);
4074 /* Fill cache first, return to user only if cache fills.
4075 We may return one of these chunks later. */
4077 && tcache
->counts
[tc_idx
] < mp_
.tcache_count
)
4079 tcache_put (victim
, tc_idx
);
4086 check_malloced_chunk (av
, victim
, nb
);
4087 void *p
= chunk2mem (victim
);
4088 alloc_perturb (p
, bytes
);
4095 /* place chunk in bin */
4097 if (in_smallbin_range (size
))
4099 victim_index
= smallbin_index (size
);
4100 bck
= bin_at (av
, victim_index
);
4105 victim_index
= largebin_index (size
);
4106 bck
= bin_at (av
, victim_index
);
4109 /* maintain large bins in sorted order */
4112 /* Or with inuse bit to speed comparisons */
4114 /* if smaller than smallest, bypass loop below */
4115 assert (chunk_main_arena (bck
->bk
));
4116 if ((unsigned long) (size
)
4117 < (unsigned long) chunksize_nomask (bck
->bk
))
4122 victim
->fd_nextsize
= fwd
->fd
;
4123 victim
->bk_nextsize
= fwd
->fd
->bk_nextsize
;
4124 fwd
->fd
->bk_nextsize
= victim
->bk_nextsize
->fd_nextsize
= victim
;
4128 assert (chunk_main_arena (fwd
));
4129 while ((unsigned long) size
< chunksize_nomask (fwd
))
4131 fwd
= fwd
->fd_nextsize
;
4132 assert (chunk_main_arena (fwd
));
4135 if ((unsigned long) size
4136 == (unsigned long) chunksize_nomask (fwd
))
4137 /* Always insert in the second position. */
4141 victim
->fd_nextsize
= fwd
;
4142 victim
->bk_nextsize
= fwd
->bk_nextsize
;
4143 if (__glibc_unlikely (fwd
->bk_nextsize
->fd_nextsize
!= fwd
))
4144 malloc_printerr ("malloc(): largebin double linked list corrupted (nextsize)");
4145 fwd
->bk_nextsize
= victim
;
4146 victim
->bk_nextsize
->fd_nextsize
= victim
;
4150 malloc_printerr ("malloc(): largebin double linked list corrupted (bk)");
4154 victim
->fd_nextsize
= victim
->bk_nextsize
= victim
;
4157 mark_bin (av
, victim_index
);
4164 /* If we've processed as many chunks as we're allowed while
4165 filling the cache, return one of the cached ones. */
4166 ++tcache_unsorted_count
;
4168 && mp_
.tcache_unsorted_limit
> 0
4169 && tcache_unsorted_count
> mp_
.tcache_unsorted_limit
)
4171 return tcache_get (tc_idx
);
4175 #define MAX_ITERS 10000
4176 if (++iters
>= MAX_ITERS
)
4181 /* If all the small chunks we found ended up cached, return one now. */
4184 return tcache_get (tc_idx
);
4189 If a large request, scan through the chunks of current bin in
4190 sorted order to find smallest that fits. Use the skip list for this.
4193 if (!in_smallbin_range (nb
))
4195 bin
= bin_at (av
, idx
);
4197 /* skip scan if empty or largest chunk is too small */
4198 if ((victim
= first (bin
)) != bin
4199 && (unsigned long) chunksize_nomask (victim
)
4200 >= (unsigned long) (nb
))
4202 victim
= victim
->bk_nextsize
;
4203 while (((unsigned long) (size
= chunksize (victim
)) <
4204 (unsigned long) (nb
)))
4205 victim
= victim
->bk_nextsize
;
4207 /* Avoid removing the first entry for a size so that the skip
4208 list does not have to be rerouted. */
4209 if (victim
!= last (bin
)
4210 && chunksize_nomask (victim
)
4211 == chunksize_nomask (victim
->fd
))
4212 victim
= victim
->fd
;
4214 remainder_size
= size
- nb
;
4215 unlink_chunk (av
, victim
);
4218 if (remainder_size
< MINSIZE
)
4220 set_inuse_bit_at_offset (victim
, size
);
4221 if (av
!= &main_arena
)
4222 set_non_main_arena (victim
);
4227 remainder
= chunk_at_offset (victim
, nb
);
4228 /* We cannot assume the unsorted list is empty and therefore
4229 have to perform a complete insert here. */
4230 bck
= unsorted_chunks (av
);
4232 if (__glibc_unlikely (fwd
->bk
!= bck
))
4233 malloc_printerr ("malloc(): corrupted unsorted chunks");
4234 remainder
->bk
= bck
;
4235 remainder
->fd
= fwd
;
4236 bck
->fd
= remainder
;
4237 fwd
->bk
= remainder
;
4238 if (!in_smallbin_range (remainder_size
))
4240 remainder
->fd_nextsize
= NULL
;
4241 remainder
->bk_nextsize
= NULL
;
4243 set_head (victim
, nb
| PREV_INUSE
|
4244 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4245 set_head (remainder
, remainder_size
| PREV_INUSE
);
4246 set_foot (remainder
, remainder_size
);
4248 check_malloced_chunk (av
, victim
, nb
);
4249 void *p
= chunk2mem (victim
);
4250 alloc_perturb (p
, bytes
);
4256 Search for a chunk by scanning bins, starting with next largest
4257 bin. This search is strictly by best-fit; i.e., the smallest
4258 (with ties going to approximately the least recently used) chunk
4259 that fits is selected.
4261 The bitmap avoids needing to check that most blocks are nonempty.
4262 The particular case of skipping all bins during warm-up phases
4263 when no chunks have been returned yet is faster than it might look.
4267 bin
= bin_at (av
, idx
);
4268 block
= idx2block (idx
);
4269 map
= av
->binmap
[block
];
4270 bit
= idx2bit (idx
);
4274 /* Skip rest of block if there are no more set bits in this block. */
4275 if (bit
> map
|| bit
== 0)
4279 if (++block
>= BINMAPSIZE
) /* out of bins */
4282 while ((map
= av
->binmap
[block
]) == 0);
4284 bin
= bin_at (av
, (block
<< BINMAPSHIFT
));
4288 /* Advance to bin with set bit. There must be one. */
4289 while ((bit
& map
) == 0)
4291 bin
= next_bin (bin
);
4296 /* Inspect the bin. It is likely to be non-empty */
4297 victim
= last (bin
);
4299 /* If a false alarm (empty bin), clear the bit. */
4302 av
->binmap
[block
] = map
&= ~bit
; /* Write through */
4303 bin
= next_bin (bin
);
4309 size
= chunksize (victim
);
4311 /* We know the first chunk in this bin is big enough to use. */
4312 assert ((unsigned long) (size
) >= (unsigned long) (nb
));
4314 remainder_size
= size
- nb
;
4317 unlink_chunk (av
, victim
);
4320 if (remainder_size
< MINSIZE
)
4322 set_inuse_bit_at_offset (victim
, size
);
4323 if (av
!= &main_arena
)
4324 set_non_main_arena (victim
);
4330 remainder
= chunk_at_offset (victim
, nb
);
4332 /* We cannot assume the unsorted list is empty and therefore
4333 have to perform a complete insert here. */
4334 bck
= unsorted_chunks (av
);
4336 if (__glibc_unlikely (fwd
->bk
!= bck
))
4337 malloc_printerr ("malloc(): corrupted unsorted chunks 2");
4338 remainder
->bk
= bck
;
4339 remainder
->fd
= fwd
;
4340 bck
->fd
= remainder
;
4341 fwd
->bk
= remainder
;
4343 /* advertise as last remainder */
4344 if (in_smallbin_range (nb
))
4345 av
->last_remainder
= remainder
;
4346 if (!in_smallbin_range (remainder_size
))
4348 remainder
->fd_nextsize
= NULL
;
4349 remainder
->bk_nextsize
= NULL
;
4351 set_head (victim
, nb
| PREV_INUSE
|
4352 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4353 set_head (remainder
, remainder_size
| PREV_INUSE
);
4354 set_foot (remainder
, remainder_size
);
4356 check_malloced_chunk (av
, victim
, nb
);
4357 void *p
= chunk2mem (victim
);
4358 alloc_perturb (p
, bytes
);
4365 If large enough, split off the chunk bordering the end of memory
4366 (held in av->top). Note that this is in accord with the best-fit
4367 search rule. In effect, av->top is treated as larger (and thus
4368 less well fitting) than any other available chunk since it can
4369 be extended to be as large as necessary (up to system
4372 We require that av->top always exists (i.e., has size >=
4373 MINSIZE) after initialization, so if it would otherwise be
4374 exhausted by current request, it is replenished. (The main
4375 reason for ensuring it exists is that we may need MINSIZE space
4376 to put in fenceposts in sysmalloc.)
4380 size
= chunksize (victim
);
4382 if (__glibc_unlikely (size
> av
->system_mem
))
4383 malloc_printerr ("malloc(): corrupted top size");
4385 if ((unsigned long) (size
) >= (unsigned long) (nb
+ MINSIZE
))
4387 remainder_size
= size
- nb
;
4388 remainder
= chunk_at_offset (victim
, nb
);
4389 av
->top
= remainder
;
4390 set_head (victim
, nb
| PREV_INUSE
|
4391 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4392 set_head (remainder
, remainder_size
| PREV_INUSE
);
4394 check_malloced_chunk (av
, victim
, nb
);
4395 void *p
= chunk2mem (victim
);
4396 alloc_perturb (p
, bytes
);
4400 /* When we are using atomic ops to free fast chunks we can get
4401 here for all block sizes. */
4402 else if (atomic_load_relaxed (&av
->have_fastchunks
))
4404 malloc_consolidate (av
);
4405 /* restore original bin index */
4406 if (in_smallbin_range (nb
))
4407 idx
= smallbin_index (nb
);
4409 idx
= largebin_index (nb
);
4413 Otherwise, relay to handle system-dependent cases
4417 void *p
= sysmalloc (nb
, av
);
4419 alloc_perturb (p
, bytes
);
4426 ------------------------------ free ------------------------------
4430 _int_free (mstate av
, mchunkptr p
, int have_lock
)
4432 INTERNAL_SIZE_T size
; /* its size */
4433 mfastbinptr
*fb
; /* associated fastbin */
4434 mchunkptr nextchunk
; /* next contiguous chunk */
4435 INTERNAL_SIZE_T nextsize
; /* its size */
4436 int nextinuse
; /* true if nextchunk is used */
4437 INTERNAL_SIZE_T prevsize
; /* size of previous contiguous chunk */
4438 mchunkptr bck
; /* misc temp for linking */
4439 mchunkptr fwd
; /* misc temp for linking */
4441 size
= chunksize (p
);
4443 /* Little security check which won't hurt performance: the
4444 allocator never wrapps around at the end of the address space.
4445 Therefore we can exclude some size values which might appear
4446 here by accident or by "design" from some intruder. */
4447 if (__builtin_expect ((uintptr_t) p
> (uintptr_t) -size
, 0)
4448 || __builtin_expect (misaligned_chunk (p
), 0))
4449 malloc_printerr ("free(): invalid pointer");
4450 /* We know that each chunk is at least MINSIZE bytes in size or a
4451 multiple of MALLOC_ALIGNMENT. */
4452 if (__glibc_unlikely (size
< MINSIZE
|| !aligned_OK (size
)))
4453 malloc_printerr ("free(): invalid size");
4455 check_inuse_chunk(av
, p
);
4459 size_t tc_idx
= csize2tidx (size
);
4460 if (tcache
!= NULL
&& tc_idx
< mp_
.tcache_bins
)
4462 /* Check to see if it's already in the tcache. */
4463 tcache_entry
*e
= (tcache_entry
*) chunk2mem (p
);
4465 /* This test succeeds on double free. However, we don't 100%
4466 trust it (it also matches random payload data at a 1 in
4467 2^<size_t> chance), so verify it's not an unlikely
4468 coincidence before aborting. */
4469 if (__glibc_unlikely (e
->key
== tcache_key
))
4473 LIBC_PROBE (memory_tcache_double_free
, 2, e
, tc_idx
);
4474 for (tmp
= tcache
->entries
[tc_idx
];
4476 tmp
= REVEAL_PTR (tmp
->next
), ++cnt
)
4478 if (cnt
>= mp_
.tcache_count
)
4479 malloc_printerr ("free(): too many chunks detected in tcache");
4480 if (__glibc_unlikely (!aligned_OK (tmp
)))
4481 malloc_printerr ("free(): unaligned chunk detected in tcache 2");
4483 malloc_printerr ("free(): double free detected in tcache 2");
4484 /* If we get here, it was a coincidence. We've wasted a
4485 few cycles, but don't abort. */
4489 if (tcache
->counts
[tc_idx
] < mp_
.tcache_count
)
4491 tcache_put (p
, tc_idx
);
4499 If eligible, place chunk on a fastbin so it can be found
4500 and used quickly in malloc.
4503 if ((unsigned long)(size
) <= (unsigned long)(get_max_fast ())
4507 If TRIM_FASTBINS set, don't place chunks
4508 bordering top into fastbins
4510 && (chunk_at_offset(p
, size
) != av
->top
)
4514 if (__builtin_expect (chunksize_nomask (chunk_at_offset (p
, size
))
4516 || __builtin_expect (chunksize (chunk_at_offset (p
, size
))
4517 >= av
->system_mem
, 0))
4520 /* We might not have a lock at this point and concurrent modifications
4521 of system_mem might result in a false positive. Redo the test after
4522 getting the lock. */
4525 __libc_lock_lock (av
->mutex
);
4526 fail
= (chunksize_nomask (chunk_at_offset (p
, size
)) <= CHUNK_HDR_SZ
4527 || chunksize (chunk_at_offset (p
, size
)) >= av
->system_mem
);
4528 __libc_lock_unlock (av
->mutex
);
4532 malloc_printerr ("free(): invalid next size (fast)");
4535 free_perturb (chunk2mem(p
), size
- CHUNK_HDR_SZ
);
4537 atomic_store_relaxed (&av
->have_fastchunks
, true);
4538 unsigned int idx
= fastbin_index(size
);
4539 fb
= &fastbin (av
, idx
);
4541 /* Atomically link P to its fastbin: P->FD = *FB; *FB = P; */
4542 mchunkptr old
= *fb
, old2
;
4544 if (SINGLE_THREAD_P
)
4546 /* Check that the top of the bin is not the record we are going to
4547 add (i.e., double free). */
4548 if (__builtin_expect (old
== p
, 0))
4549 malloc_printerr ("double free or corruption (fasttop)");
4550 p
->fd
= PROTECT_PTR (&p
->fd
, old
);
4556 /* Check that the top of the bin is not the record we are going to
4557 add (i.e., double free). */
4558 if (__builtin_expect (old
== p
, 0))
4559 malloc_printerr ("double free or corruption (fasttop)");
4561 p
->fd
= PROTECT_PTR (&p
->fd
, old
);
4563 while ((old
= catomic_compare_and_exchange_val_rel (fb
, p
, old2
))
4566 /* Check that size of fastbin chunk at the top is the same as
4567 size of the chunk that we are adding. We can dereference OLD
4568 only if we have the lock, otherwise it might have already been
4570 if (have_lock
&& old
!= NULL
4571 && __builtin_expect (fastbin_index (chunksize (old
)) != idx
, 0))
4572 malloc_printerr ("invalid fastbin entry (free)");
4576 Consolidate other non-mmapped chunks as they arrive.
4579 else if (!chunk_is_mmapped(p
)) {
4581 /* If we're single-threaded, don't lock the arena. */
4582 if (SINGLE_THREAD_P
)
4586 __libc_lock_lock (av
->mutex
);
4588 nextchunk
= chunk_at_offset(p
, size
);
4590 /* Lightweight tests: check whether the block is already the
4592 if (__glibc_unlikely (p
== av
->top
))
4593 malloc_printerr ("double free or corruption (top)");
4594 /* Or whether the next chunk is beyond the boundaries of the arena. */
4595 if (__builtin_expect (contiguous (av
)
4596 && (char *) nextchunk
4597 >= ((char *) av
->top
+ chunksize(av
->top
)), 0))
4598 malloc_printerr ("double free or corruption (out)");
4599 /* Or whether the block is actually not marked used. */
4600 if (__glibc_unlikely (!prev_inuse(nextchunk
)))
4601 malloc_printerr ("double free or corruption (!prev)");
4603 nextsize
= chunksize(nextchunk
);
4604 if (__builtin_expect (chunksize_nomask (nextchunk
) <= CHUNK_HDR_SZ
, 0)
4605 || __builtin_expect (nextsize
>= av
->system_mem
, 0))
4606 malloc_printerr ("free(): invalid next size (normal)");
4608 free_perturb (chunk2mem(p
), size
- CHUNK_HDR_SZ
);
4610 /* consolidate backward */
4611 if (!prev_inuse(p
)) {
4612 prevsize
= prev_size (p
);
4614 p
= chunk_at_offset(p
, -((long) prevsize
));
4615 if (__glibc_unlikely (chunksize(p
) != prevsize
))
4616 malloc_printerr ("corrupted size vs. prev_size while consolidating");
4617 unlink_chunk (av
, p
);
4620 if (nextchunk
!= av
->top
) {
4621 /* get and clear inuse bit */
4622 nextinuse
= inuse_bit_at_offset(nextchunk
, nextsize
);
4624 /* consolidate forward */
4626 unlink_chunk (av
, nextchunk
);
4629 clear_inuse_bit_at_offset(nextchunk
, 0);
4632 Place the chunk in unsorted chunk list. Chunks are
4633 not placed into regular bins until after they have
4634 been given one chance to be used in malloc.
4637 bck
= unsorted_chunks(av
);
4639 if (__glibc_unlikely (fwd
->bk
!= bck
))
4640 malloc_printerr ("free(): corrupted unsorted chunks");
4643 if (!in_smallbin_range(size
))
4645 p
->fd_nextsize
= NULL
;
4646 p
->bk_nextsize
= NULL
;
4651 set_head(p
, size
| PREV_INUSE
);
4654 check_free_chunk(av
, p
);
4658 If the chunk borders the current high end of memory,
4659 consolidate into top
4664 set_head(p
, size
| PREV_INUSE
);
4670 If freeing a large space, consolidate possibly-surrounding
4671 chunks. Then, if the total unused topmost memory exceeds trim
4672 threshold, ask malloc_trim to reduce top.
4674 Unless max_fast is 0, we don't know if there are fastbins
4675 bordering top, so we cannot tell for sure whether threshold
4676 has been reached unless fastbins are consolidated. But we
4677 don't want to consolidate on each free. As a compromise,
4678 consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
4682 if ((unsigned long)(size
) >= FASTBIN_CONSOLIDATION_THRESHOLD
) {
4683 if (atomic_load_relaxed (&av
->have_fastchunks
))
4684 malloc_consolidate(av
);
4686 if (av
== &main_arena
) {
4687 #ifndef MORECORE_CANNOT_TRIM
4688 if ((unsigned long)(chunksize(av
->top
)) >=
4689 (unsigned long)(mp_
.trim_threshold
))
4690 systrim(mp_
.top_pad
, av
);
4693 /* Always try heap_trim(), even if the top chunk is not
4694 large, because the corresponding heap might go away. */
4695 heap_info
*heap
= heap_for_ptr(top(av
));
4697 assert(heap
->ar_ptr
== av
);
4698 heap_trim(heap
, mp_
.top_pad
);
4703 __libc_lock_unlock (av
->mutex
);
4706 If the chunk was allocated via mmap, release via munmap().
4715 ------------------------- malloc_consolidate -------------------------
4717 malloc_consolidate is a specialized version of free() that tears
4718 down chunks held in fastbins. Free itself cannot be used for this
4719 purpose since, among other things, it might place chunks back onto
4720 fastbins. So, instead, we need to use a minor variant of the same
4724 static void malloc_consolidate(mstate av
)
4726 mfastbinptr
* fb
; /* current fastbin being consolidated */
4727 mfastbinptr
* maxfb
; /* last fastbin (for loop control) */
4728 mchunkptr p
; /* current chunk being consolidated */
4729 mchunkptr nextp
; /* next chunk to consolidate */
4730 mchunkptr unsorted_bin
; /* bin header */
4731 mchunkptr first_unsorted
; /* chunk to link to */
4733 /* These have same use as in free() */
4734 mchunkptr nextchunk
;
4735 INTERNAL_SIZE_T size
;
4736 INTERNAL_SIZE_T nextsize
;
4737 INTERNAL_SIZE_T prevsize
;
4740 atomic_store_relaxed (&av
->have_fastchunks
, false);
4742 unsorted_bin
= unsorted_chunks(av
);
4745 Remove each chunk from fast bin and consolidate it, placing it
4746 then in unsorted bin. Among other reasons for doing this,
4747 placing in unsorted bin avoids needing to calculate actual bins
4748 until malloc is sure that chunks aren't immediately going to be
4752 maxfb
= &fastbin (av
, NFASTBINS
- 1);
4753 fb
= &fastbin (av
, 0);
4755 p
= atomic_exchange_acq (fb
, NULL
);
4759 if (__glibc_unlikely (misaligned_chunk (p
)))
4760 malloc_printerr ("malloc_consolidate(): "
4761 "unaligned fastbin chunk detected");
4763 unsigned int idx
= fastbin_index (chunksize (p
));
4764 if ((&fastbin (av
, idx
)) != fb
)
4765 malloc_printerr ("malloc_consolidate(): invalid chunk size");
4768 check_inuse_chunk(av
, p
);
4769 nextp
= REVEAL_PTR (p
->fd
);
4771 /* Slightly streamlined version of consolidation code in free() */
4772 size
= chunksize (p
);
4773 nextchunk
= chunk_at_offset(p
, size
);
4774 nextsize
= chunksize(nextchunk
);
4776 if (!prev_inuse(p
)) {
4777 prevsize
= prev_size (p
);
4779 p
= chunk_at_offset(p
, -((long) prevsize
));
4780 if (__glibc_unlikely (chunksize(p
) != prevsize
))
4781 malloc_printerr ("corrupted size vs. prev_size in fastbins");
4782 unlink_chunk (av
, p
);
4785 if (nextchunk
!= av
->top
) {
4786 nextinuse
= inuse_bit_at_offset(nextchunk
, nextsize
);
4790 unlink_chunk (av
, nextchunk
);
4792 clear_inuse_bit_at_offset(nextchunk
, 0);
4794 first_unsorted
= unsorted_bin
->fd
;
4795 unsorted_bin
->fd
= p
;
4796 first_unsorted
->bk
= p
;
4798 if (!in_smallbin_range (size
)) {
4799 p
->fd_nextsize
= NULL
;
4800 p
->bk_nextsize
= NULL
;
4803 set_head(p
, size
| PREV_INUSE
);
4804 p
->bk
= unsorted_bin
;
4805 p
->fd
= first_unsorted
;
4811 set_head(p
, size
| PREV_INUSE
);
4815 } while ( (p
= nextp
) != 0);
4818 } while (fb
++ != maxfb
);
4822 ------------------------------ realloc ------------------------------
4826 _int_realloc (mstate av
, mchunkptr oldp
, INTERNAL_SIZE_T oldsize
,
4829 mchunkptr newp
; /* chunk to return */
4830 INTERNAL_SIZE_T newsize
; /* its size */
4831 void* newmem
; /* corresponding user mem */
4833 mchunkptr next
; /* next contiguous chunk after oldp */
4835 mchunkptr remainder
; /* extra space at end of newp */
4836 unsigned long remainder_size
; /* its size */
4839 if (__builtin_expect (chunksize_nomask (oldp
) <= CHUNK_HDR_SZ
, 0)
4840 || __builtin_expect (oldsize
>= av
->system_mem
, 0))
4841 malloc_printerr ("realloc(): invalid old size");
4843 check_inuse_chunk (av
, oldp
);
4845 /* All callers already filter out mmap'ed chunks. */
4846 assert (!chunk_is_mmapped (oldp
));
4848 next
= chunk_at_offset (oldp
, oldsize
);
4849 INTERNAL_SIZE_T nextsize
= chunksize (next
);
4850 if (__builtin_expect (chunksize_nomask (next
) <= CHUNK_HDR_SZ
, 0)
4851 || __builtin_expect (nextsize
>= av
->system_mem
, 0))
4852 malloc_printerr ("realloc(): invalid next size");
4854 if ((unsigned long) (oldsize
) >= (unsigned long) (nb
))
4856 /* already big enough; split below */
4863 /* Try to expand forward into top */
4864 if (next
== av
->top
&&
4865 (unsigned long) (newsize
= oldsize
+ nextsize
) >=
4866 (unsigned long) (nb
+ MINSIZE
))
4868 set_head_size (oldp
, nb
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4869 av
->top
= chunk_at_offset (oldp
, nb
);
4870 set_head (av
->top
, (newsize
- nb
) | PREV_INUSE
);
4871 check_inuse_chunk (av
, oldp
);
4872 return tag_new_usable (chunk2mem (oldp
));
4875 /* Try to expand forward into next chunk; split off remainder below */
4876 else if (next
!= av
->top
&&
4878 (unsigned long) (newsize
= oldsize
+ nextsize
) >=
4879 (unsigned long) (nb
))
4882 unlink_chunk (av
, next
);
4885 /* allocate, copy, free */
4888 newmem
= _int_malloc (av
, nb
- MALLOC_ALIGN_MASK
);
4890 return 0; /* propagate failure */
4892 newp
= mem2chunk (newmem
);
4893 newsize
= chunksize (newp
);
4896 Avoid copy if newp is next chunk after oldp.
4905 void *oldmem
= chunk2mem (oldp
);
4906 size_t sz
= memsize (oldp
);
4907 (void) tag_region (oldmem
, sz
);
4908 newmem
= tag_new_usable (newmem
);
4909 memcpy (newmem
, oldmem
, sz
);
4910 _int_free (av
, oldp
, 1);
4911 check_inuse_chunk (av
, newp
);
4917 /* If possible, free extra space in old or extended chunk */
4919 assert ((unsigned long) (newsize
) >= (unsigned long) (nb
));
4921 remainder_size
= newsize
- nb
;
4923 if (remainder_size
< MINSIZE
) /* not enough extra to split off */
4925 set_head_size (newp
, newsize
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4926 set_inuse_bit_at_offset (newp
, newsize
);
4928 else /* split remainder */
4930 remainder
= chunk_at_offset (newp
, nb
);
4931 /* Clear any user-space tags before writing the header. */
4932 remainder
= tag_region (remainder
, remainder_size
);
4933 set_head_size (newp
, nb
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4934 set_head (remainder
, remainder_size
| PREV_INUSE
|
4935 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
4936 /* Mark remainder as inuse so free() won't complain */
4937 set_inuse_bit_at_offset (remainder
, remainder_size
);
4938 _int_free (av
, remainder
, 1);
4941 check_inuse_chunk (av
, newp
);
4942 return tag_new_usable (chunk2mem (newp
));
4946 ------------------------------ memalign ------------------------------
4950 _int_memalign (mstate av
, size_t alignment
, size_t bytes
)
4952 INTERNAL_SIZE_T nb
; /* padded request size */
4953 char *m
; /* memory returned by malloc call */
4954 mchunkptr p
; /* corresponding chunk */
4955 char *brk
; /* alignment point within p */
4956 mchunkptr newp
; /* chunk to return */
4957 INTERNAL_SIZE_T newsize
; /* its size */
4958 INTERNAL_SIZE_T leadsize
; /* leading space before alignment point */
4959 mchunkptr remainder
; /* spare room at end to split off */
4960 unsigned long remainder_size
; /* its size */
4961 INTERNAL_SIZE_T size
;
4965 if (!checked_request2size (bytes
, &nb
))
4967 __set_errno (ENOMEM
);
4972 Strategy: find a spot within that chunk that meets the alignment
4973 request, and then possibly free the leading and trailing space.
4976 /* Call malloc with worst case padding to hit alignment. */
4978 m
= (char *) (_int_malloc (av
, nb
+ alignment
+ MINSIZE
));
4981 return 0; /* propagate failure */
4985 if ((((unsigned long) (m
)) % alignment
) != 0) /* misaligned */
4988 Find an aligned spot inside chunk. Since we need to give back
4989 leading space in a chunk of at least MINSIZE, if the first
4990 calculation places us at a spot with less than MINSIZE leader,
4991 we can move to the next aligned spot -- we've allocated enough
4992 total room so that this is always possible.
4994 brk
= (char *) mem2chunk (((unsigned long) (m
+ alignment
- 1)) &
4995 - ((signed long) alignment
));
4996 if ((unsigned long) (brk
- (char *) (p
)) < MINSIZE
)
4999 newp
= (mchunkptr
) brk
;
5000 leadsize
= brk
- (char *) (p
);
5001 newsize
= chunksize (p
) - leadsize
;
5003 /* For mmapped chunks, just adjust offset */
5004 if (chunk_is_mmapped (p
))
5006 set_prev_size (newp
, prev_size (p
) + leadsize
);
5007 set_head (newp
, newsize
| IS_MMAPPED
);
5008 return chunk2mem (newp
);
5011 /* Otherwise, give back leader, use the rest */
5012 set_head (newp
, newsize
| PREV_INUSE
|
5013 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
5014 set_inuse_bit_at_offset (newp
, newsize
);
5015 set_head_size (p
, leadsize
| (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
5016 _int_free (av
, p
, 1);
5019 assert (newsize
>= nb
&&
5020 (((unsigned long) (chunk2mem (p
))) % alignment
) == 0);
5023 /* Also give back spare room at the end */
5024 if (!chunk_is_mmapped (p
))
5026 size
= chunksize (p
);
5027 if ((unsigned long) (size
) > (unsigned long) (nb
+ MINSIZE
))
5029 remainder_size
= size
- nb
;
5030 remainder
= chunk_at_offset (p
, nb
);
5031 set_head (remainder
, remainder_size
| PREV_INUSE
|
5032 (av
!= &main_arena
? NON_MAIN_ARENA
: 0));
5033 set_head_size (p
, nb
);
5034 _int_free (av
, remainder
, 1);
5038 check_inuse_chunk (av
, p
);
5039 return chunk2mem (p
);
5044 ------------------------------ malloc_trim ------------------------------
5048 mtrim (mstate av
, size_t pad
)
5050 /* Ensure all blocks are consolidated. */
5051 malloc_consolidate (av
);
5053 const size_t ps
= GLRO (dl_pagesize
);
5054 int psindex
= bin_index (ps
);
5055 const size_t psm1
= ps
- 1;
5058 for (int i
= 1; i
< NBINS
; ++i
)
5059 if (i
== 1 || i
>= psindex
)
5061 mbinptr bin
= bin_at (av
, i
);
5063 for (mchunkptr p
= last (bin
); p
!= bin
; p
= p
->bk
)
5065 INTERNAL_SIZE_T size
= chunksize (p
);
5067 if (size
> psm1
+ sizeof (struct malloc_chunk
))
5069 /* See whether the chunk contains at least one unused page. */
5070 char *paligned_mem
= (char *) (((uintptr_t) p
5071 + sizeof (struct malloc_chunk
)
5074 assert ((char *) chunk2mem (p
) + 2 * CHUNK_HDR_SZ
5076 assert ((char *) p
+ size
> paligned_mem
);
5078 /* This is the size we could potentially free. */
5079 size
-= paligned_mem
- (char *) p
;
5084 /* When debugging we simulate destroying the memory
5086 memset (paligned_mem
, 0x89, size
& ~psm1
);
5088 __madvise (paligned_mem
, size
& ~psm1
, MADV_DONTNEED
);
5096 #ifndef MORECORE_CANNOT_TRIM
5097 return result
| (av
== &main_arena
? systrim (pad
, av
) : 0);
5106 __malloc_trim (size_t s
)
5110 if (__malloc_initialized
< 0)
5113 mstate ar_ptr
= &main_arena
;
5116 __libc_lock_lock (ar_ptr
->mutex
);
5117 result
|= mtrim (ar_ptr
, s
);
5118 __libc_lock_unlock (ar_ptr
->mutex
);
5120 ar_ptr
= ar_ptr
->next
;
5122 while (ar_ptr
!= &main_arena
);
5129 ------------------------- malloc_usable_size -------------------------
5140 p
= mem2chunk (mem
);
5142 if (__builtin_expect (using_malloc_checking
== 1, 0))
5143 return malloc_check_get_size (p
);
5145 if (chunk_is_mmapped (p
))
5147 if (DUMPED_MAIN_ARENA_CHUNK (p
))
5148 result
= chunksize (p
) - SIZE_SZ
;
5150 result
= chunksize (p
) - CHUNK_HDR_SZ
;
5153 result
= memsize (p
);
5162 __malloc_usable_size (void *m
)
5166 result
= musable (m
);
5171 ------------------------------ mallinfo ------------------------------
5172 Accumulate malloc statistics for arena AV into M.
5176 int_mallinfo (mstate av
, struct mallinfo2
*m
)
5181 INTERNAL_SIZE_T avail
;
5182 INTERNAL_SIZE_T fastavail
;
5186 check_malloc_state (av
);
5188 /* Account for top */
5189 avail
= chunksize (av
->top
);
5190 nblocks
= 1; /* top always exists */
5192 /* traverse fastbins */
5196 for (i
= 0; i
< NFASTBINS
; ++i
)
5198 for (p
= fastbin (av
, i
);
5200 p
= REVEAL_PTR (p
->fd
))
5202 if (__glibc_unlikely (misaligned_chunk (p
)))
5203 malloc_printerr ("int_mallinfo(): "
5204 "unaligned fastbin chunk detected");
5206 fastavail
+= chunksize (p
);
5212 /* traverse regular bins */
5213 for (i
= 1; i
< NBINS
; ++i
)
5216 for (p
= last (b
); p
!= b
; p
= p
->bk
)
5219 avail
+= chunksize (p
);
5223 m
->smblks
+= nfastblocks
;
5224 m
->ordblks
+= nblocks
;
5225 m
->fordblks
+= avail
;
5226 m
->uordblks
+= av
->system_mem
- avail
;
5227 m
->arena
+= av
->system_mem
;
5228 m
->fsmblks
+= fastavail
;
5229 if (av
== &main_arena
)
5231 m
->hblks
= mp_
.n_mmaps
;
5232 m
->hblkhd
= mp_
.mmapped_mem
;
5234 m
->keepcost
= chunksize (av
->top
);
5240 __libc_mallinfo2 (void)
5245 if (__malloc_initialized
< 0)
5248 memset (&m
, 0, sizeof (m
));
5249 ar_ptr
= &main_arena
;
5252 __libc_lock_lock (ar_ptr
->mutex
);
5253 int_mallinfo (ar_ptr
, &m
);
5254 __libc_lock_unlock (ar_ptr
->mutex
);
5256 ar_ptr
= ar_ptr
->next
;
5258 while (ar_ptr
!= &main_arena
);
5262 libc_hidden_def (__libc_mallinfo2
)
5265 __libc_mallinfo (void)
5268 struct mallinfo2 m2
= __libc_mallinfo2 ();
5271 m
.ordblks
= m2
.ordblks
;
5272 m
.smblks
= m2
.smblks
;
5274 m
.hblkhd
= m2
.hblkhd
;
5275 m
.usmblks
= m2
.usmblks
;
5276 m
.fsmblks
= m2
.fsmblks
;
5277 m
.uordblks
= m2
.uordblks
;
5278 m
.fordblks
= m2
.fordblks
;
5279 m
.keepcost
= m2
.keepcost
;
5286 ------------------------------ malloc_stats ------------------------------
5290 __malloc_stats (void)
5294 unsigned int in_use_b
= mp_
.mmapped_mem
, system_b
= in_use_b
;
5296 if (__malloc_initialized
< 0)
5298 _IO_flockfile (stderr
);
5299 int old_flags2
= stderr
->_flags2
;
5300 stderr
->_flags2
|= _IO_FLAGS2_NOTCANCEL
;
5301 for (i
= 0, ar_ptr
= &main_arena
;; i
++)
5303 struct mallinfo2 mi
;
5305 memset (&mi
, 0, sizeof (mi
));
5306 __libc_lock_lock (ar_ptr
->mutex
);
5307 int_mallinfo (ar_ptr
, &mi
);
5308 fprintf (stderr
, "Arena %d:\n", i
);
5309 fprintf (stderr
, "system bytes = %10u\n", (unsigned int) mi
.arena
);
5310 fprintf (stderr
, "in use bytes = %10u\n", (unsigned int) mi
.uordblks
);
5311 #if MALLOC_DEBUG > 1
5313 dump_heap (heap_for_ptr (top (ar_ptr
)));
5315 system_b
+= mi
.arena
;
5316 in_use_b
+= mi
.uordblks
;
5317 __libc_lock_unlock (ar_ptr
->mutex
);
5318 ar_ptr
= ar_ptr
->next
;
5319 if (ar_ptr
== &main_arena
)
5322 fprintf (stderr
, "Total (incl. mmap):\n");
5323 fprintf (stderr
, "system bytes = %10u\n", system_b
);
5324 fprintf (stderr
, "in use bytes = %10u\n", in_use_b
);
5325 fprintf (stderr
, "max mmap regions = %10u\n", (unsigned int) mp_
.max_n_mmaps
);
5326 fprintf (stderr
, "max mmap bytes = %10lu\n",
5327 (unsigned long) mp_
.max_mmapped_mem
);
5328 stderr
->_flags2
= old_flags2
;
5329 _IO_funlockfile (stderr
);
5334 ------------------------------ mallopt ------------------------------
5336 static __always_inline
int
5337 do_set_trim_threshold (size_t value
)
5339 LIBC_PROBE (memory_mallopt_trim_threshold
, 3, value
, mp_
.trim_threshold
,
5340 mp_
.no_dyn_threshold
);
5341 mp_
.trim_threshold
= value
;
5342 mp_
.no_dyn_threshold
= 1;
5346 static __always_inline
int
5347 do_set_top_pad (size_t value
)
5349 LIBC_PROBE (memory_mallopt_top_pad
, 3, value
, mp_
.top_pad
,
5350 mp_
.no_dyn_threshold
);
5351 mp_
.top_pad
= value
;
5352 mp_
.no_dyn_threshold
= 1;
5356 static __always_inline
int
5357 do_set_mmap_threshold (size_t value
)
5359 /* Forbid setting the threshold too high. */
5360 if (value
<= HEAP_MAX_SIZE
/ 2)
5362 LIBC_PROBE (memory_mallopt_mmap_threshold
, 3, value
, mp_
.mmap_threshold
,
5363 mp_
.no_dyn_threshold
);
5364 mp_
.mmap_threshold
= value
;
5365 mp_
.no_dyn_threshold
= 1;
5371 static __always_inline
int
5372 do_set_mmaps_max (int32_t value
)
5374 LIBC_PROBE (memory_mallopt_mmap_max
, 3, value
, mp_
.n_mmaps_max
,
5375 mp_
.no_dyn_threshold
);
5376 mp_
.n_mmaps_max
= value
;
5377 mp_
.no_dyn_threshold
= 1;
5381 static __always_inline
int
5382 do_set_mallopt_check (int32_t value
)
5387 static __always_inline
int
5388 do_set_perturb_byte (int32_t value
)
5390 LIBC_PROBE (memory_mallopt_perturb
, 2, value
, perturb_byte
);
5391 perturb_byte
= value
;
5395 static __always_inline
int
5396 do_set_arena_test (size_t value
)
5398 LIBC_PROBE (memory_mallopt_arena_test
, 2, value
, mp_
.arena_test
);
5399 mp_
.arena_test
= value
;
5403 static __always_inline
int
5404 do_set_arena_max (size_t value
)
5406 LIBC_PROBE (memory_mallopt_arena_max
, 2, value
, mp_
.arena_max
);
5407 mp_
.arena_max
= value
;
5412 static __always_inline
int
5413 do_set_tcache_max (size_t value
)
5415 if (value
<= MAX_TCACHE_SIZE
)
5417 LIBC_PROBE (memory_tunable_tcache_max_bytes
, 2, value
, mp_
.tcache_max_bytes
);
5418 mp_
.tcache_max_bytes
= value
;
5419 mp_
.tcache_bins
= csize2tidx (request2size(value
)) + 1;
5425 static __always_inline
int
5426 do_set_tcache_count (size_t value
)
5428 if (value
<= MAX_TCACHE_COUNT
)
5430 LIBC_PROBE (memory_tunable_tcache_count
, 2, value
, mp_
.tcache_count
);
5431 mp_
.tcache_count
= value
;
5437 static __always_inline
int
5438 do_set_tcache_unsorted_limit (size_t value
)
5440 LIBC_PROBE (memory_tunable_tcache_unsorted_limit
, 2, value
, mp_
.tcache_unsorted_limit
);
5441 mp_
.tcache_unsorted_limit
= value
;
5448 do_set_mxfast (size_t value
)
5450 if (value
<= MAX_FAST_SIZE
)
5452 LIBC_PROBE (memory_mallopt_mxfast
, 2, value
, get_max_fast ());
5453 set_max_fast (value
);
5460 __libc_mallopt (int param_number
, int value
)
5462 mstate av
= &main_arena
;
5465 if (__malloc_initialized
< 0)
5467 __libc_lock_lock (av
->mutex
);
5469 LIBC_PROBE (memory_mallopt
, 2, param_number
, value
);
5471 /* We must consolidate main arena before changing max_fast
5472 (see definition of set_max_fast). */
5473 malloc_consolidate (av
);
5475 /* Many of these helper functions take a size_t. We do not worry
5476 about overflow here, because negative int values will wrap to
5477 very large size_t values and the helpers have sufficient range
5478 checking for such conversions. Many of these helpers are also
5479 used by the tunables macros in arena.c. */
5481 switch (param_number
)
5484 res
= do_set_mxfast (value
);
5487 case M_TRIM_THRESHOLD
:
5488 res
= do_set_trim_threshold (value
);
5492 res
= do_set_top_pad (value
);
5495 case M_MMAP_THRESHOLD
:
5496 res
= do_set_mmap_threshold (value
);
5500 res
= do_set_mmaps_max (value
);
5503 case M_CHECK_ACTION
:
5504 res
= do_set_mallopt_check (value
);
5508 res
= do_set_perturb_byte (value
);
5513 res
= do_set_arena_test (value
);
5518 res
= do_set_arena_max (value
);
5521 __libc_lock_unlock (av
->mutex
);
5524 libc_hidden_def (__libc_mallopt
)
5528 -------------------- Alternative MORECORE functions --------------------
5533 General Requirements for MORECORE.
5535 The MORECORE function must have the following properties:
5537 If MORECORE_CONTIGUOUS is false:
5539 * MORECORE must allocate in multiples of pagesize. It will
5540 only be called with arguments that are multiples of pagesize.
5542 * MORECORE(0) must return an address that is at least
5543 MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
5545 else (i.e. If MORECORE_CONTIGUOUS is true):
5547 * Consecutive calls to MORECORE with positive arguments
5548 return increasing addresses, indicating that space has been
5549 contiguously extended.
5551 * MORECORE need not allocate in multiples of pagesize.
5552 Calls to MORECORE need not have args of multiples of pagesize.
5554 * MORECORE need not page-align.
5558 * MORECORE may allocate more memory than requested. (Or even less,
5559 but this will generally result in a malloc failure.)
5561 * MORECORE must not allocate memory when given argument zero, but
5562 instead return one past the end address of memory from previous
5563 nonzero call. This malloc does NOT call MORECORE(0)
5564 until at least one call with positive arguments is made, so
5565 the initial value returned is not important.
5567 * Even though consecutive calls to MORECORE need not return contiguous
5568 addresses, it must be OK for malloc'ed chunks to span multiple
5569 regions in those cases where they do happen to be contiguous.
5571 * MORECORE need not handle negative arguments -- it may instead
5572 just return MORECORE_FAILURE when given negative arguments.
5573 Negative arguments are always multiples of pagesize. MORECORE
5574 must not misinterpret negative args as large positive unsigned
5575 args. You can suppress all such calls from even occurring by defining
5576 MORECORE_CANNOT_TRIM,
5578 There is some variation across systems about the type of the
5579 argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
5580 actually be size_t, because sbrk supports negative args, so it is
5581 normally the signed type of the same width as size_t (sometimes
5582 declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
5583 matter though. Internally, we use "long" as arguments, which should
5584 work across all reasonable possibilities.
5586 Additionally, if MORECORE ever returns failure for a positive
5587 request, then mmap is used as a noncontiguous system allocator. This
5588 is a useful backup strategy for systems with holes in address spaces
5589 -- in this case sbrk cannot contiguously expand the heap, but mmap
5590 may be able to map noncontiguous space.
5592 If you'd like mmap to ALWAYS be used, you can define MORECORE to be
5593 a function that always returns MORECORE_FAILURE.
5595 If you are using this malloc with something other than sbrk (or its
5596 emulation) to supply memory regions, you probably want to set
5597 MORECORE_CONTIGUOUS as false. As an example, here is a custom
5598 allocator kindly contributed for pre-OSX macOS. It uses virtually
5599 but not necessarily physically contiguous non-paged memory (locked
5600 in, present and won't get swapped out). You can use it by
5601 uncommenting this section, adding some #includes, and setting up the
5602 appropriate defines above:
5604 *#define MORECORE osMoreCore
5605 *#define MORECORE_CONTIGUOUS 0
5607 There is also a shutdown routine that should somehow be called for
5608 cleanup upon program exit.
5610 *#define MAX_POOL_ENTRIES 100
5611 *#define MINIMUM_MORECORE_SIZE (64 * 1024)
5612 static int next_os_pool;
5613 void *our_os_pools[MAX_POOL_ENTRIES];
5615 void *osMoreCore(int size)
5618 static void *sbrk_top = 0;
5622 if (size < MINIMUM_MORECORE_SIZE)
5623 size = MINIMUM_MORECORE_SIZE;
5624 if (CurrentExecutionLevel() == kTaskLevel)
5625 ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
5628 return (void *) MORECORE_FAILURE;
5630 // save ptrs so they can be freed during cleanup
5631 our_os_pools[next_os_pool] = ptr;
5633 ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
5634 sbrk_top = (char *) ptr + size;
5639 // we don't currently support shrink behavior
5640 return (void *) MORECORE_FAILURE;
5648 // cleanup any allocated memory pools
5649 // called as last thing before shutting down driver
5651 void osCleanupMem(void)
5655 for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
5658 PoolDeallocate(*ptr);
5668 extern char **__libc_argv attribute_hidden
;
5671 malloc_printerr (const char *str
)
5673 __libc_message (do_abort
, "%s\n", str
);
5674 __builtin_unreachable ();
5677 /* We need a wrapper function for one of the additions of POSIX. */
5679 __posix_memalign (void **memptr
, size_t alignment
, size_t size
)
5683 /* Test whether the SIZE argument is valid. It must be a power of
5684 two multiple of sizeof (void *). */
5685 if (alignment
% sizeof (void *) != 0
5686 || !powerof2 (alignment
/ sizeof (void *))
5691 void *address
= RETURN_ADDRESS (0);
5692 mem
= _mid_memalign (alignment
, size
, address
);
5702 weak_alias (__posix_memalign
, posix_memalign
)
5706 __malloc_info (int options
, FILE *fp
)
5708 /* For now, at least. */
5713 size_t total_nblocks
= 0;
5714 size_t total_nfastblocks
= 0;
5715 size_t total_avail
= 0;
5716 size_t total_fastavail
= 0;
5717 size_t total_system
= 0;
5718 size_t total_max_system
= 0;
5719 size_t total_aspace
= 0;
5720 size_t total_aspace_mprotect
= 0;
5724 if (__malloc_initialized
< 0)
5727 fputs ("<malloc version=\"1\">\n", fp
);
5729 /* Iterate over all arenas currently in use. */
5730 mstate ar_ptr
= &main_arena
;
5733 fprintf (fp
, "<heap nr=\"%d\">\n<sizes>\n", n
++);
5736 size_t nfastblocks
= 0;
5738 size_t fastavail
= 0;
5745 } sizes
[NFASTBINS
+ NBINS
- 1];
5746 #define nsizes (sizeof (sizes) / sizeof (sizes[0]))
5748 __libc_lock_lock (ar_ptr
->mutex
);
5750 /* Account for top chunk. The top-most available chunk is
5751 treated specially and is never in any bin. See "initial_top"
5753 avail
= chunksize (ar_ptr
->top
);
5754 nblocks
= 1; /* Top always exists. */
5756 for (size_t i
= 0; i
< NFASTBINS
; ++i
)
5758 mchunkptr p
= fastbin (ar_ptr
, i
);
5761 size_t nthissize
= 0;
5762 size_t thissize
= chunksize (p
);
5766 if (__glibc_unlikely (misaligned_chunk (p
)))
5767 malloc_printerr ("__malloc_info(): "
5768 "unaligned fastbin chunk detected");
5770 p
= REVEAL_PTR (p
->fd
);
5773 fastavail
+= nthissize
* thissize
;
5774 nfastblocks
+= nthissize
;
5775 sizes
[i
].from
= thissize
- (MALLOC_ALIGNMENT
- 1);
5776 sizes
[i
].to
= thissize
;
5777 sizes
[i
].count
= nthissize
;
5780 sizes
[i
].from
= sizes
[i
].to
= sizes
[i
].count
= 0;
5782 sizes
[i
].total
= sizes
[i
].count
* sizes
[i
].to
;
5787 struct malloc_chunk
*r
;
5789 for (size_t i
= 1; i
< NBINS
; ++i
)
5791 bin
= bin_at (ar_ptr
, i
);
5793 sizes
[NFASTBINS
- 1 + i
].from
= ~((size_t) 0);
5794 sizes
[NFASTBINS
- 1 + i
].to
= sizes
[NFASTBINS
- 1 + i
].total
5795 = sizes
[NFASTBINS
- 1 + i
].count
= 0;
5800 size_t r_size
= chunksize_nomask (r
);
5801 ++sizes
[NFASTBINS
- 1 + i
].count
;
5802 sizes
[NFASTBINS
- 1 + i
].total
+= r_size
;
5803 sizes
[NFASTBINS
- 1 + i
].from
5804 = MIN (sizes
[NFASTBINS
- 1 + i
].from
, r_size
);
5805 sizes
[NFASTBINS
- 1 + i
].to
= MAX (sizes
[NFASTBINS
- 1 + i
].to
,
5811 if (sizes
[NFASTBINS
- 1 + i
].count
== 0)
5812 sizes
[NFASTBINS
- 1 + i
].from
= 0;
5813 nblocks
+= sizes
[NFASTBINS
- 1 + i
].count
;
5814 avail
+= sizes
[NFASTBINS
- 1 + i
].total
;
5817 size_t heap_size
= 0;
5818 size_t heap_mprotect_size
= 0;
5819 size_t heap_count
= 0;
5820 if (ar_ptr
!= &main_arena
)
5822 /* Iterate over the arena heaps from back to front. */
5823 heap_info
*heap
= heap_for_ptr (top (ar_ptr
));
5826 heap_size
+= heap
->size
;
5827 heap_mprotect_size
+= heap
->mprotect_size
;
5831 while (heap
!= NULL
);
5834 __libc_lock_unlock (ar_ptr
->mutex
);
5836 total_nfastblocks
+= nfastblocks
;
5837 total_fastavail
+= fastavail
;
5839 total_nblocks
+= nblocks
;
5840 total_avail
+= avail
;
5842 for (size_t i
= 0; i
< nsizes
; ++i
)
5843 if (sizes
[i
].count
!= 0 && i
!= NFASTBINS
)
5845 <size from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5846 sizes
[i
].from
, sizes
[i
].to
, sizes
[i
].total
, sizes
[i
].count
);
5848 if (sizes
[NFASTBINS
].count
!= 0)
5850 <unsorted from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5851 sizes
[NFASTBINS
].from
, sizes
[NFASTBINS
].to
,
5852 sizes
[NFASTBINS
].total
, sizes
[NFASTBINS
].count
);
5854 total_system
+= ar_ptr
->system_mem
;
5855 total_max_system
+= ar_ptr
->max_system_mem
;
5858 "</sizes>\n<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5859 "<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5860 "<system type=\"current\" size=\"%zu\"/>\n"
5861 "<system type=\"max\" size=\"%zu\"/>\n",
5862 nfastblocks
, fastavail
, nblocks
, avail
,
5863 ar_ptr
->system_mem
, ar_ptr
->max_system_mem
);
5865 if (ar_ptr
!= &main_arena
)
5868 "<aspace type=\"total\" size=\"%zu\"/>\n"
5869 "<aspace type=\"mprotect\" size=\"%zu\"/>\n"
5870 "<aspace type=\"subheaps\" size=\"%zu\"/>\n",
5871 heap_size
, heap_mprotect_size
, heap_count
);
5872 total_aspace
+= heap_size
;
5873 total_aspace_mprotect
+= heap_mprotect_size
;
5878 "<aspace type=\"total\" size=\"%zu\"/>\n"
5879 "<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5880 ar_ptr
->system_mem
, ar_ptr
->system_mem
);
5881 total_aspace
+= ar_ptr
->system_mem
;
5882 total_aspace_mprotect
+= ar_ptr
->system_mem
;
5885 fputs ("</heap>\n", fp
);
5886 ar_ptr
= ar_ptr
->next
;
5888 while (ar_ptr
!= &main_arena
);
5891 "<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5892 "<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5893 "<total type=\"mmap\" count=\"%d\" size=\"%zu\"/>\n"
5894 "<system type=\"current\" size=\"%zu\"/>\n"
5895 "<system type=\"max\" size=\"%zu\"/>\n"
5896 "<aspace type=\"total\" size=\"%zu\"/>\n"
5897 "<aspace type=\"mprotect\" size=\"%zu\"/>\n"
5899 total_nfastblocks
, total_fastavail
, total_nblocks
, total_avail
,
5900 mp_
.n_mmaps
, mp_
.mmapped_mem
,
5901 total_system
, total_max_system
,
5902 total_aspace
, total_aspace_mprotect
);
5906 weak_alias (__malloc_info
, malloc_info
)
5909 strong_alias (__libc_calloc
, __calloc
) weak_alias (__libc_calloc
, calloc
)
5910 strong_alias (__libc_free
, __free
) strong_alias (__libc_free
, free
)
5911 strong_alias (__libc_malloc
, __malloc
) strong_alias (__libc_malloc
, malloc
)
5912 strong_alias (__libc_memalign
, __memalign
)
5913 weak_alias (__libc_memalign
, memalign
)
5914 strong_alias (__libc_realloc
, __realloc
) strong_alias (__libc_realloc
, realloc
)
5915 strong_alias (__libc_valloc
, __valloc
) weak_alias (__libc_valloc
, valloc
)
5916 strong_alias (__libc_pvalloc
, __pvalloc
) weak_alias (__libc_pvalloc
, pvalloc
)
5917 strong_alias (__libc_mallinfo
, __mallinfo
)
5918 weak_alias (__libc_mallinfo
, mallinfo
)
5919 strong_alias (__libc_mallinfo2
, __mallinfo2
)
5920 weak_alias (__libc_mallinfo2
, mallinfo2
)
5921 strong_alias (__libc_mallopt
, __mallopt
) weak_alias (__libc_mallopt
, mallopt
)
5923 weak_alias (__malloc_stats
, malloc_stats
)
5924 weak_alias (__malloc_usable_size
, malloc_usable_size
)
5925 weak_alias (__malloc_trim
, malloc_trim
)
5927 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
5928 compat_symbol (libc
, __libc_free
, cfree
, GLIBC_2_0
);
5931 /* ------------------------------------------------------------
5934 [see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]