1 /* Initialization for access to a mmap'd malloc managed region. */
3 /* Copyright (c) 2012-2022. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 /* Copyright 1992, 2000 Free Software Foundation, Inc.
11 Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
13 This file is part of the GNU C Library.
15 The GNU C Library is free software; you can redistribute it and/or
16 modify it under the terms of the GNU Library General Public License as
17 published by the Free Software Foundation; either version 2 of the
18 License, or (at your option) any later version.
20 The GNU C Library is distributed in the hope that it will be useful,
21 but WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 Library General Public License for more details.
25 You should have received a copy of the GNU Library General Public
26 License along with the GNU C Library; see the file COPYING.LIB. If
27 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
28 Boston, MA 02111-1307, USA. */
30 #include <sys/types.h>
31 #include <fcntl.h> /* After sys/types.h, at least for dpx/2. */
34 #include "mmprivate.h"
36 /* Initialize access to a mmalloc managed region.
38 The mapping is established starting at the specified address BASEADDR
39 in the process address space.
41 The provided BASEADDR should be chosen carefully in order to avoid
42 bumping into existing mapped regions or future mapped regions.
44 On success, returns a "malloc descriptor" which is used in subsequent
45 calls to other mmalloc package functions. It is explicitly "void *"
46 so that users of the package don't have to worry about the actual
47 implementation details.
49 On failure, returns NULL. */
51 xbt_mheap_t xbt_mheap_new(void* baseaddr, int options)
53 /* NULL is not a valid baseaddr as we cannot map anything there. C'mon, user. Think! */
57 /* We start off with the malloc descriptor allocated on the stack, until we build it up enough to
58 * call _mmalloc_mmap_morecore() to allocate the first page of the region and copy it there. Ensure that it is
59 * zero'd and then initialize the fields that we know values for. */
62 xbt_mheap_t mdp = &mtemp;
63 memset((char *) mdp, 0, sizeof(mtemp));
64 strncpy(mdp->magic, MMALLOC_MAGIC, MMALLOC_MAGIC_SIZE);
65 mdp->headersize = sizeof(mtemp);
66 mdp->version = MMALLOC_VERSION;
67 mdp->base = mdp->breakval = mdp->top = baseaddr;
68 mdp->next_mdesc = NULL;
69 mdp->options = options;
71 pthread_mutex_init(&mdp->mutex, NULL);
72 /* If we have not been passed a valid open file descriptor for the file
73 to map to, then open /dev/zero and use that to map to. */
75 /* Now try to map in the first page, copy the malloc descriptor structure there, and arrange to return a pointer to
76 * this new copy. If the mapping fails, then close the file descriptor if it was opened by us, and arrange to return
79 void* mbase = mmorecore(mdp, sizeof(mtemp));
81 fprintf(stderr, "morecore failed to get some more memory!\n");
84 memcpy(mbase, mdp, sizeof(mtemp));
86 /* Add the new heap to the linked list of heaps attached by mmalloc */
87 if(__mmalloc_default_mdp){
88 mdp = __mmalloc_default_mdp;
89 while(mdp->next_mdesc)
90 mdp = mdp->next_mdesc;
93 mdp->next_mdesc = (struct mdesc *)mbase;
102 /** Terminate access to a mmalloc managed region, but do not free its content.
104 * This is for example useful for the base region where ldl stores its data
105 * because it leaves the place after us.
107 void xbt_mheap_destroy_no_free(xbt_mheap_t md)
109 struct mdesc *mdp = md;
111 pthread_mutex_destroy(&mdp->mutex);
114 /** Terminate access to a mmalloc managed region by unmapping all memory pages associated with the region, and closing
115 * the file descriptor if it is one that we opened.
117 Returns NULL on success.
119 Returns the malloc descriptor on failure, which can subsequently be used for further action, such as obtaining more
120 information about the nature of the failure.
122 Note that the malloc descriptor that we are using is currently located in region we are about to unmap, so we first
123 make a local copy of it on the stack and use the copy. */
125 void *xbt_mheap_destroy(xbt_mheap_t mdp)
128 /* Remove the heap from the linked list of heaps attached by mmalloc */
129 struct mdesc* mdptemp = __mmalloc_default_mdp;
130 while(mdptemp->next_mdesc != mdp )
131 mdptemp = mdptemp->next_mdesc;
133 mdptemp->next_mdesc = mdp->next_mdesc;
135 xbt_mheap_destroy_no_free(mdp);
136 struct mdesc mtemp = *mdp;
138 /* Now unmap all the pages associated with this region by asking for a
139 negative increment equal to the current size of the region. */
141 if (mmorecore(&mtemp, (char *)mtemp.base - (char *)mtemp.breakval) == NULL) {
142 /* Deallocating failed. Update the original malloc descriptor with any changes */
152 /* Safety gap from the heap's break address.
153 * Try to increase this first if you experience strange errors under valgrind. */
154 #define HEAP_OFFSET (128UL<<20)
156 static void mmalloc_fork_prepare(void)
158 xbt_mheap_t mdp = NULL;
159 if ((mdp =__mmalloc_default_mdp)){
162 mdp = mdp->next_mdesc;
167 static void mmalloc_fork_parent(void)
169 xbt_mheap_t mdp = NULL;
170 if ((mdp =__mmalloc_default_mdp)){
173 mdp = mdp->next_mdesc;
178 static void mmalloc_fork_child(void)
180 struct mdesc* mdp = NULL;
181 if ((mdp =__mmalloc_default_mdp)){
184 mdp = mdp->next_mdesc;
189 /* Initialize the default malloc descriptor.
191 * There is no malloc_postexit() destroying the default mdp, because it would break ldl trying to free its memory
193 xbt_mheap_t mmalloc_preinit(void)
195 if (__mmalloc_default_mdp == NULL) {
196 if (!mmalloc_pagesize)
197 mmalloc_pagesize = getpagesize();
198 unsigned long mask = ~((unsigned long)mmalloc_pagesize - 1);
199 void* addr = (void*)(((unsigned long)sbrk(0) + HEAP_OFFSET) & mask);
200 __mmalloc_default_mdp = xbt_mheap_new(addr, XBT_MHEAP_OPTION_MEMSET);
202 // atfork mandated at least on FreeBSD, or simgrid-mc will fail to fork the verified app
203 int res = pthread_atfork(mmalloc_fork_prepare, mmalloc_fork_parent, mmalloc_fork_child);
204 mmalloc_assert(res == 0, "pthread_atfork() failed: return value %d", res);
206 mmalloc_assert(__mmalloc_default_mdp != NULL, "__mmalloc_default_mdp cannot be NULL");
208 return __mmalloc_default_mdp;