1 /* Initialization for access to a mmap'd malloc managed region.
2 Copyright 1992, 2000 Free Software Foundation, Inc.
4 Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
6 This file is part of the GNU C Library.
8 The GNU C Library is free software; you can redistribute it and/or
9 modify it under the terms of the GNU Library General Public License as
10 published by the Free Software Foundation; either version 2 of the
11 License, or (at your option) any later version.
13 The GNU C Library is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Library General Public License for more details.
18 You should have received a copy of the GNU Library General Public
19 License along with the GNU C Library; see the file COPYING.LIB. If
20 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 #include <sys/types.h>
24 #include <fcntl.h> /* After sys/types.h, at least for dpx/2. */
28 #include <unistd.h> /* Prototypes for lseek */
30 #include "mmprivate.h"
32 #include "xbt_modinter.h" /* declarations of mmalloc_preinit and friends that live here */
38 /* Initialize access to a mmalloc managed region.
40 If FD is a valid file descriptor for an open file then data for the
41 mmalloc managed region is mapped to that file, otherwise an anonymous
42 map is used if supported by the underlying OS. In case of running in
43 an OS without support of anonymous mappings then "/dev/zero" is used
44 and in both cases the data will not exist in any filesystem object.
46 If the open file corresponding to FD is from a previous use of
47 mmalloc and passes some basic sanity checks to ensure that it is
48 compatible with the current mmalloc package, then its data is
49 mapped in and is immediately accessible at the same addresses in
50 the current process as the process that created the file (ignoring
51 the BASEADDR parameter).
53 For non valid FDs or empty files ones the mapping is established
54 starting at the specified address BASEADDR in the process address
57 The provided BASEADDR should be choosed carefully in order to avoid
58 bumping into existing mapped regions or future mapped regions.
60 On success, returns a "malloc descriptor" which is used in subsequent
61 calls to other mmalloc package functions. It is explicitly "void *"
62 so that users of the package don't have to worry about the actual
63 implementation details.
65 On failure returns NULL. */
67 xbt_mheap_t xbt_mheap_new(int fd, void *baseaddr)
74 /* First check to see if FD is a valid file descriptor, and if so, see
75 if the file has any current contents (size > 0). If it does, then
76 attempt to reuse the file. If we can't reuse the file, either
77 because it isn't a valid mmalloc produced file, was produced by an
78 obsolete version, or any other reason, then we fail to attach to
82 if (fstat(fd, &sbuf) < 0)
85 else if (sbuf.st_size > 0) {
86 /* We were given an valid file descriptor on an open file, so try to remap
87 it into the current process at the same address to which it was previously
88 mapped. It naturally have to pass some sanity checks for that.
90 Note that we have to update the file descriptor number in the malloc-
91 descriptor read from the file to match the current valid one, before
92 trying to map the file in, and again after a successful mapping and
93 after we've switched over to using the mapped in malloc descriptor
94 rather than the temporary one on the stack.
96 Once we've switched over to using the mapped in malloc descriptor, we
97 have to update the pointer to the morecore function, since it almost
98 certainly will be at a different address if the process reusing the
99 mapped region is from a different executable.
101 Also note that if the heap being remapped previously used the mmcheckf()
102 routines, we need to update the hooks since their target functions
103 will have certainly moved if the executable has changed in any way.
104 We do this by calling mmcheckf() internally.
106 Returns a pointer to the malloc descriptor if successful, or NULL if
107 unsuccessful for some reason. */
110 struct mdesc *mdptr = NULL, *mdptemp = NULL;
112 if (lseek(fd, 0L, SEEK_SET) != 0)
114 if (read(fd, (char *) &newmd, sizeof(newmd)) != sizeof(newmd))
116 if (newmd.headersize != sizeof(newmd))
118 if (strcmp(newmd.magic, MMALLOC_MAGIC) != 0)
120 if (newmd.version > MMALLOC_VERSION)
124 if (__mmalloc_remap_core(&newmd) == newmd.base) {
125 mdptr = (struct mdesc *) newmd.base;
127 if(!mdptr->refcount){
128 sem_init(&mdptr->sem, 0, 1);
133 /* Add the new heap to the linked list of heaps attached by mmalloc */
134 mdptemp = __mmalloc_default_mdp;
135 while(mdptemp->next_mdesc)
136 mdptemp = mdptemp->next_mdesc;
139 mdptemp->next_mdesc = mdptr;
146 /* NULL is not a valid baseaddr as we cannot map anything there.
147 C'mon, user. Think! */
148 if (baseaddr == NULL)
151 /* We start off with the malloc descriptor allocated on the stack, until
152 we build it up enough to call _mmalloc_mmap_morecore() to allocate the
153 first page of the region and copy it there. Ensure that it is zero'd and
154 then initialize the fields that we know values for. */
157 memset((char *) mdp, 0, sizeof(mtemp));
158 strncpy(mdp->magic, MMALLOC_MAGIC, MMALLOC_MAGIC_SIZE);
159 mdp->headersize = sizeof(mtemp);
160 mdp->version = MMALLOC_VERSION;
162 mdp->base = mdp->breakval = mdp->top = baseaddr;
163 mdp->next_mdesc = NULL;
166 /* If we have not been passed a valid open file descriptor for the file
167 to map to, then we go for an anonymous map */
170 mdp->flags |= MMALLOC_ANONYMOUS;
172 sem_init(&mdp->sem, 0, 1);
174 /* If we have not been passed a valid open file descriptor for the file
175 to map to, then open /dev/zero and use that to map to. */
177 /* Now try to map in the first page, copy the malloc descriptor structure
178 there, and arrange to return a pointer to this new copy. If the mapping
179 fails, then close the file descriptor if it was opened by us, and arrange
182 if ((mbase = mmorecore(mdp, sizeof(mtemp))) != NULL) {
183 memcpy(mbase, mdp, sizeof(mtemp));
185 fprintf(stderr, "morecore failed to get some more memory!\n");
189 /* Add the new heap to the linked list of heaps attached by mmalloc */
190 if(__mmalloc_default_mdp){
191 mdp = __mmalloc_default_mdp;
192 while(mdp->next_mdesc)
193 mdp = mdp->next_mdesc;
196 mdp->next_mdesc = (struct mdesc *)mbase;
205 /** Terminate access to a mmalloc managed region, but do not free its content.
207 * This is for example useful for the base region where ldl stores its data
208 * because it leaves the place after us.
210 void xbt_mheap_destroy_no_free(xbt_mheap_t md)
212 struct mdesc *mdp = md;
214 if(--mdp->refcount == 0){
216 sem_destroy(&mdp->sem);
220 /** Terminate access to a mmalloc managed region by unmapping all memory pages
221 associated with the region, and closing the file descriptor if it is one
224 Returns NULL on success.
226 Returns the malloc descriptor on failure, which can subsequently be used
227 for further action, such as obtaining more information about the nature of
230 Note that the malloc descriptor that we are using is currently located in
231 region we are about to unmap, so we first make a local copy of it on the
232 stack and use the copy. */
234 void *xbt_mheap_destroy(xbt_mheap_t mdp)
236 struct mdesc mtemp, *mdptemp;
239 /* Remove the heap from the linked list of heaps attached by mmalloc */
240 mdptemp = __mmalloc_default_mdp;
241 while(mdptemp->next_mdesc != mdp )
242 mdptemp = mdptemp->next_mdesc;
244 mdptemp->next_mdesc = mdp->next_mdesc;
246 xbt_mheap_destroy_no_free(mdp);
249 /* Now unmap all the pages associated with this region by asking for a
250 negative increment equal to the current size of the region. */
252 if (mmorecore(&mtemp, (char *)mtemp.base - (char *)mtemp.breakval) == NULL) {
253 /* Deallocating failed. Update the original malloc descriptor
257 if (mtemp.flags & MMALLOC_DEVZERO) {
267 /* Safety gap from the heap's break address.
268 * Try to increase this first if you experience strange errors under
270 #define HEAP_OFFSET (128UL<<20)
272 xbt_mheap_t mmalloc_get_default_md(void)
274 xbt_assert(__mmalloc_default_mdp);
275 return __mmalloc_default_mdp;
278 static void mmalloc_fork_prepare(void)
280 xbt_mheap_t mdp = NULL;
281 if ((mdp =__mmalloc_default_mdp)){
287 mdp = mdp->next_mdesc;
292 static void mmalloc_fork_parent(void)
294 xbt_mheap_t mdp = NULL;
295 if ((mdp =__mmalloc_default_mdp)){
299 mdp = mdp->next_mdesc;
304 static void mmalloc_fork_child(void)
306 struct mdesc* mdp = NULL;
307 if ((mdp =__mmalloc_default_mdp)){
310 mdp = mdp->next_mdesc;
315 /* Initialize the default malloc descriptor. */
316 void *mmalloc_preinit(void)
319 if (__mmalloc_default_mdp == NULL) {
320 unsigned long mask = ~((unsigned long)getpagesize() - 1);
321 void *addr = (void*)(((unsigned long)sbrk(0) + HEAP_OFFSET) & mask);
322 __mmalloc_default_mdp = xbt_mheap_new(-1, addr);
323 /* Fixme? only the default mdp in protected against forks */
324 // This is mandated to protect the mmalloced areas through forks. Think of tesh.
325 // Nah, removing the mutex isn't a good idea either for tesh
326 res = xbt_os_thread_atfork(mmalloc_fork_prepare,
327 mmalloc_fork_parent, mmalloc_fork_child);
329 THROWF(system_error,0,"xbt_os_thread_atfork() failed: return value %d",res);
331 xbt_assert(__mmalloc_default_mdp != NULL);
333 #if defined(HAVE_GNU_LD) && defined(MMALLOC_WANT_OVERRIDE_LEGACY)
334 mm_gnuld_legacy_init();
337 return __mmalloc_default_mdp;
340 void mmalloc_postexit(void)
342 /* Do not destroy the default mdp or ldl won't be able to free the memory it
343 * allocated since we're in memory */
344 // xbt_mheap_destroy_no_free(__mmalloc_default_mdp);
347 size_t mmalloc_get_bytes_used(xbt_mheap_t heap){
351 while(i<=((struct mdesc *)heap)->heaplimit){
352 if(((struct mdesc *)heap)->heapinfo[i].type == 0){
353 if(((struct mdesc *)heap)->heapinfo[i].busy_block.busy_size > 0)
354 bytes += ((struct mdesc *)heap)->heapinfo[i].busy_block.busy_size;
356 }else if(((struct mdesc *)heap)->heapinfo[i].type > 0){
357 for(j=0; j < (size_t) (BLOCKSIZE >> ((struct mdesc *)heap)->heapinfo[i].type); j++){
358 if(((struct mdesc *)heap)->heapinfo[i].busy_frag.frag_size[j] > 0)
359 bytes += ((struct mdesc *)heap)->heapinfo[i].busy_frag.frag_size[j];
368 ssize_t mmalloc_get_busy_size(xbt_mheap_t heap, void *ptr){
370 ssize_t block = ((char*)ptr - (char*)(heap->heapbase)) / BLOCKSIZE + 1;
371 if(heap->heapinfo[block].type == -1)
373 else if(heap->heapinfo[block].type == 0)
374 return heap->heapinfo[block].busy_block.busy_size;
376 ssize_t frag = ((uintptr_t) (ADDR2UINT (ptr) % (BLOCKSIZE))) >> heap->heapinfo[block].type;
377 return heap->heapinfo[block].busy_frag.frag_size[frag];