1 /* Initialization for access to a mmap'd malloc managed region. */
3 /* Copyright (c) 2012-2023. The SimGrid Team. All rights reserved. */
5 /* This program is free software; you can redistribute it and/or modify it
6 * under the terms of the license (GNU LGPL) which comes with this package. */
8 /* Copyright 1992, 2000 Free Software Foundation, Inc.
10 Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
12 This file is part of the GNU C Library.
14 The GNU C Library is free software; you can redistribute it and/or
15 modify it under the terms of the GNU Library General Public License as
16 published by the Free Software Foundation; either version 2 of the
17 License, or (at your option) any later version.
19 The GNU C Library is distributed in the hope that it will be useful,
20 but WITHOUT ANY WARRANTY; without even the implied warranty of
21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 Library General Public License for more details.
24 You should have received a copy of the GNU Library General Public
25 License along with the GNU C Library; see the file COPYING.LIB. If
26 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
27 Boston, MA 02111-1307, USA. */
29 #include <sys/types.h>
30 #include <fcntl.h> /* After sys/types.h, at least for dpx/2. */
33 #include "mmprivate.h"
35 /* Initialize access to a mmalloc managed region.
37 The mapping is established starting at the specified address BASEADDR
38 in the process address space.
40 The provided BASEADDR should be chosen carefully in order to avoid
41 bumping into existing mapped regions or future mapped regions.
43 On success, returns a "malloc descriptor" which is used in subsequent
44 calls to other mmalloc package functions. It is explicitly "void *"
45 so that users of the package don't have to worry about the actual
46 implementation details.
48 On failure, returns NULL. */
50 xbt_mheap_t xbt_mheap_new(void* baseaddr, int options)
52 /* NULL is not a valid baseaddr as we cannot map anything there. C'mon, user. Think! */
56 /* We start off with the malloc descriptor allocated on the stack, until we build it up enough to
57 * call _mmalloc_mmap_morecore() to allocate the first page of the region and copy it there. Ensure that it is
58 * zero'd and then initialize the fields that we know values for. */
61 xbt_mheap_t mdp = &mtemp;
62 memset((char *) mdp, 0, sizeof(mtemp));
63 strncpy(mdp->magic, MMALLOC_MAGIC, MMALLOC_MAGIC_SIZE);
64 mdp->headersize = sizeof(mtemp);
65 mdp->version = MMALLOC_VERSION;
66 mdp->base = mdp->breakval = mdp->top = baseaddr;
67 mdp->next_mdesc = NULL;
68 mdp->options = options;
70 /* If we have not been passed a valid open file descriptor for the file
71 to map to, then open /dev/zero and use that to map to. */
73 /* Now try to map in the first page, copy the malloc descriptor structure there, and arrange to return a pointer to
74 * this new copy. If the mapping fails, then close the file descriptor if it was opened by us, and arrange to return
77 void* mbase = mmorecore(mdp, sizeof(mtemp));
79 fprintf(stderr, "morecore failed to get some more memory!\n");
82 memcpy(mbase, mdp, sizeof(mtemp));
84 /* Add the new heap to the linked list of heaps attached by mmalloc */
85 if(__mmalloc_default_mdp){
86 mdp = __mmalloc_default_mdp;
87 while(mdp->next_mdesc)
88 mdp = mdp->next_mdesc;
90 mdp->next_mdesc = (struct mdesc *)mbase;
96 /** Terminate access to a mmalloc managed region by unmapping all memory pages associated with the region, and closing
97 * the file descriptor if it is one that we opened.
99 Returns NULL on success.
101 Returns the malloc descriptor on failure, which can subsequently be used for further action, such as obtaining more
102 information about the nature of the failure.
104 Note that the malloc descriptor that we are using is currently located in region we are about to unmap, so we first
105 make a local copy of it on the stack and use the copy. */
107 void *xbt_mheap_destroy(xbt_mheap_t mdp)
110 /* Remove the heap from the linked list of heaps attached by mmalloc */
111 struct mdesc* mdptemp = __mmalloc_default_mdp;
112 while(mdptemp->next_mdesc != mdp )
113 mdptemp = mdptemp->next_mdesc;
115 mdptemp->next_mdesc = mdp->next_mdesc;
117 struct mdesc mtemp = *mdp;
119 /* Now unmap all the pages associated with this region by asking for a
120 negative increment equal to the current size of the region. */
122 if (mmorecore(&mtemp, (char *)mtemp.base - (char *)mtemp.breakval) == NULL) {
123 /* Deallocating failed. Update the original malloc descriptor with any changes */
133 /* Safety gap from the heap's break address.
134 * Try to increase this first if you experience strange errors under valgrind. */
135 #define HEAP_OFFSET (128UL<<20)
137 /* Initialize the default malloc descriptor.
139 * There is no malloc_postexit() destroying the default mdp, because it would break ldl trying to free its memory
141 xbt_mheap_t mmalloc_preinit(void)
143 if (__mmalloc_default_mdp == NULL) {
144 unsigned long mmalloc_pagesize = (unsigned long)sysconf(_SC_PAGESIZE);
145 unsigned long mask = ~(mmalloc_pagesize - 1);
146 void* addr = (void*)(((unsigned long)sbrk(0) + HEAP_OFFSET) & mask);
147 __mmalloc_default_mdp = xbt_mheap_new(addr, XBT_MHEAP_OPTION_MEMSET);
149 mmalloc_assert(__mmalloc_default_mdp != NULL, "__mmalloc_default_mdp cannot be NULL");
151 return __mmalloc_default_mdp;