1 /* Memory allocator `malloc'. */
3 /* Copyright (c) 2010-2018. 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 1990, 1991, 1992 Free Software Foundation
10 Written May 1989 by Mike Haertel.
11 Heavily modified Mar 1992 by Fred Fish for mmap'd version. */
13 #include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
15 #include "mmprivate.h"
17 /* Prototypes for local functions */
19 static void initialize(xbt_mheap_t mdp);
20 static void *register_morecore(xbt_mheap_t mdp, size_t size);
21 static void *align(xbt_mheap_t mdp, size_t size);
23 /* Allocation aligned on block boundary.
25 * It never returns NULL, but dies verbosely on error.
27 static void *align(struct mdesc *mdp, size_t size)
30 unsigned long int adj;
32 result = mmorecore(mdp, size);
34 /* if this reservation does not fill up the last block of our resa,
35 * complete the reservation by also asking for the full latest block.
37 * Also, the returned block is aligned to the end of block (but I've
38 * no fucking idea of why, actually -- http://abstrusegoose.com/432 --
39 * but not doing so seems to lead to issues).
41 adj = RESIDUAL(result, BLOCKSIZE);
43 adj = BLOCKSIZE - adj;
45 result = (char *) result + adj;
50 /** Initialise heapinfo about the heapinfo pages :)
53 static void initialize_heapinfo_heapinfo(xbt_mheap_t mdp)
55 // Update heapinfo about the heapinfo pages (!):
56 xbt_assert((uintptr_t) mdp->heapinfo % BLOCKSIZE == 0);
57 int block = BLOCK(mdp->heapinfo);
58 size_t nblocks = mdp->heapsize * sizeof(malloc_info) / BLOCKSIZE;
60 for (size_t j=0; j!=nblocks; ++j) {
61 mdp->heapinfo[block+j].type = MMALLOC_TYPE_FREE;
62 mdp->heapinfo[block+j].free_block.size = 0;
63 mdp->heapinfo[block+j].free_block.next = 0;
64 mdp->heapinfo[block+j].free_block.prev = 0;
66 mdp->heapinfo[block].free_block.size = nblocks;
69 /* Finish the initialization of the mheap. If we want to inline it
70 * properly, we need to make the align function publicly visible, too */
71 static void initialize(xbt_mheap_t mdp)
74 malloc_info mi; /* to compute the offset of the swag hook */
76 // Update mdp meta-data:
77 mdp->heapsize = HEAP / BLOCKSIZE;
78 mdp->heapinfo = (malloc_info *)
79 align(mdp, mdp->heapsize * sizeof(malloc_info));
80 mdp->heapbase = (void *) mdp->heapinfo;
81 mdp->flags |= MMALLOC_INITIALIZED;
83 // Update root heapinfo:
84 memset((void *) mdp->heapinfo, 0, mdp->heapsize * sizeof(malloc_info));
85 mdp->heapinfo[0].type = MMALLOC_TYPE_FREE;
86 mdp->heapinfo[0].free_block.size = 0;
87 mdp->heapinfo[0].free_block.next = mdp->heapinfo[0].free_block.prev = 0;
90 initialize_heapinfo_heapinfo(mdp);
92 for (i=0;i<BLOCKLOG;i++) {
93 xbt_swag_init(&(mdp->fraghead[i]),
94 xbt_swag_offset(mi, freehook));
98 static inline void update_hook(void **a, size_t offset)
101 *a = (char*)*a + offset;
104 /* Get neatly aligned memory from the low level layers, and register it
105 * into the heap info table as necessary. */
106 static void *register_morecore(struct mdesc *mdp, size_t size)
108 void* result = align(mdp, size); // Never returns NULL
110 /* Check if we need to grow the info table (in a multiplicative manner) */
111 if ((size_t) BLOCK((char *) result + size) > mdp->heapsize) {
114 size_t newsize = mdp->heapsize;
115 while ((size_t) BLOCK((char *) result + size) > newsize)
118 /* Copy old info into new location */
119 malloc_info* oldinfo = mdp->heapinfo;
120 malloc_info* newinfo = (malloc_info*)align(mdp, newsize * sizeof(malloc_info));
121 memcpy(newinfo, oldinfo, mdp->heapsize * sizeof(malloc_info));
123 /* Initialise the new blockinfo : */
124 memset((char*) newinfo + mdp->heapsize * sizeof(malloc_info), 0,
125 (newsize - mdp->heapsize)* sizeof(malloc_info));
127 /* Update the swag of busy blocks containing free fragments by applying the offset to all swag_hooks. Yeah. My hand is right in the fan and I still type */
128 size_t offset=((char*)newinfo)-((char*)oldinfo);
130 for (int i = 1 /*first element of heapinfo describes the mdesc area*/; i < mdp->heaplimit; i++) {
131 update_hook(&newinfo[i].freehook.next, offset);
132 update_hook(&newinfo[i].freehook.prev, offset);
134 // also update the starting points of the swag
135 for (int i = 0; i < BLOCKLOG; i++) {
136 update_hook(&mdp->fraghead[i].head, offset);
137 update_hook(&mdp->fraghead[i].tail, offset);
139 mdp->heapinfo = newinfo;
141 /* mark the space previously occupied by the block info as free by first marking it
142 * as occupied in the regular way, and then freing it */
143 for (it=0; it<BLOCKIFY(mdp->heapsize * sizeof(malloc_info)); it++){
144 newinfo[BLOCK(oldinfo)+it].type = MMALLOC_TYPE_UNFRAGMENTED;
145 newinfo[BLOCK(oldinfo)+it].busy_block.ignore = 0;
148 newinfo[BLOCK(oldinfo)].busy_block.size = BLOCKIFY(mdp->heapsize * sizeof(malloc_info));
149 newinfo[BLOCK(oldinfo)].busy_block.busy_size = size;
150 mfree(mdp, (void *) oldinfo);
151 mdp->heapsize = newsize;
153 initialize_heapinfo_heapinfo(mdp);
156 mdp->heaplimit = BLOCK((char *) result + size);
160 /* Allocate memory from the heap. */
161 void *mmalloc(xbt_mheap_t mdp, size_t size) {
162 void *res= mmalloc_no_memset(mdp,size);
163 if (mdp->options & XBT_MHEAP_OPTION_MEMSET) {
169 static void mmalloc_mark_used(xbt_mheap_t mdp, size_t block, size_t nblocks, size_t requested_size)
171 for (int it = 0; it < nblocks; it++) {
172 mdp->heapinfo[block + it].type = MMALLOC_TYPE_UNFRAGMENTED;
173 mdp->heapinfo[block + it].busy_block.busy_size = 0;
174 mdp->heapinfo[block + it].busy_block.ignore = 0;
175 mdp->heapinfo[block + it].busy_block.size = 0;
177 mdp->heapinfo[block].busy_block.size = nblocks;
178 mdp->heapinfo[block].busy_block.busy_size = requested_size;
179 // mdp->heapinfo[block].busy_block.bt_size =
180 // xbt_backtrace_no_malloc(mdp->heapinfo[block].busy_block.bt, XBT_BACKTRACE_SIZE);
181 // mdp->heapinfo[block].busy_block.bt_size =
182 // xbt_libunwind_backtrace(mdp->heapinfo[block].busy_block.bt, XBT_BACKTRACE_SIZE);
183 mdp->heapstats.chunks_used++;
184 mdp->heapstats.bytes_used += nblocks * BLOCKSIZE;
187 /* Spliting mmalloc this way is mandated by a trick in mrealloc, that gives
188 back the memory of big blocks to the system before reallocating them: we don't
189 want to loose the beginning of the area when this happens */
190 void *mmalloc_no_memset(xbt_mheap_t mdp, size_t size)
195 size_t requested_size = size; // The amount of memory requested by user, for real
197 /* Work even if the user was stupid enough to ask a ridiculously small block (even 0-length),
198 * ie return a valid block that can be realloced and freed.
199 * glibc malloc does not use this trick but return a constant pointer, but we need to enlist the free fragments later on.
201 if (size < SMALLEST_POSSIBLE_MALLOC)
202 size = SMALLEST_POSSIBLE_MALLOC;
204 // printf("(%s) Mallocing %d bytes on %p (default: %p)...",xbt_thread_self_name(),size,mdp,__mmalloc_default_mdp);fflush(stdout);
206 if (!(mdp->flags & MMALLOC_INITIALIZED))
209 /* Determine the allocation policy based on the request size. */
210 if (size <= BLOCKSIZE / 2) {
211 /* Small allocation to receive a fragment of a block.
212 Determine the logarithm to base two of the fragment size. */
215 while ((size /= 2) != 0) {
219 /* Look in the fragment lists for a free fragment of the desired size. */
220 if (xbt_swag_size(&mdp->fraghead[log])>0) {
221 /* There are free fragments of this size; Get one of them and prepare to return it.
222 Update the block's nfree and if no other free fragment, get out of the swag. */
224 /* search a fragment that I could return as a result */
225 malloc_info *candidate_info = xbt_swag_getFirst(&mdp->fraghead[log]);
226 size_t candidate_block = (candidate_info - &(mdp->heapinfo[0]));
227 size_t candidate_frag;
228 for (candidate_frag=0;candidate_frag<(size_t) (BLOCKSIZE >> log);candidate_frag++)
229 if (candidate_info->busy_frag.frag_size[candidate_frag] == -1)
231 xbt_assert(candidate_frag < (size_t) (BLOCKSIZE >> log),
232 "Block %zu was registered as containing free fragments of type %zu, but I can't find any",candidate_block,log);
234 result = (void*) (((char*)ADDRESS(candidate_block)) + (candidate_frag << log));
236 /* Remove this fragment from the list of free guys */
237 candidate_info->busy_frag.nfree--;
238 if (candidate_info->busy_frag.nfree == 0) {
239 xbt_swag_remove(candidate_info,&mdp->fraghead[log]);
242 /* Update our metadata about this fragment */
243 candidate_info->busy_frag.frag_size[candidate_frag] = requested_size;
244 candidate_info->busy_frag.ignore[candidate_frag] = 0;
245 //xbt_backtrace_no_malloc(candidate_info->busy_frag.bt[candidate_frag],XBT_BACKTRACE_SIZE);
246 //xbt_libunwind_backtrace(candidate_info->busy_frag.bt[candidate_frag],XBT_BACKTRACE_SIZE);
248 /* Update the statistics. */
249 mdp -> heapstats.chunks_used++;
250 mdp -> heapstats.bytes_used += 1 << log;
251 mdp -> heapstats.chunks_free--;
252 mdp -> heapstats.bytes_free -= 1 << log;
255 /* No free fragments of the desired size, so get a new block
256 and break it into fragments, returning the first. */
258 result = mmalloc(mdp, BLOCKSIZE); // does not return NULL
259 block = BLOCK(result);
261 mdp->heapinfo[block].type = log;
262 /* Link all fragments but the first as free, and add the block to the swag of blocks containing free frags */
264 for (i = 1; i < (size_t) (BLOCKSIZE >> log); ++i) {
265 mdp->heapinfo[block].busy_frag.frag_size[i] = -1;
266 mdp->heapinfo[block].busy_frag.ignore[i] = 0;
268 mdp->heapinfo[block].busy_frag.nfree = i - 1;
269 mdp->heapinfo[block].freehook.prev = NULL;
270 mdp->heapinfo[block].freehook.next = NULL;
272 xbt_swag_insert(&mdp->heapinfo[block], &(mdp->fraghead[log]));
274 /* mark the fragment returned as busy */
275 mdp->heapinfo[block].busy_frag.frag_size[0] = requested_size;
276 mdp->heapinfo[block].busy_frag.ignore[0] = 0;
277 //xbt_backtrace_no_malloc(mdp->heapinfo[block].busy_frag.bt[0],XBT_BACKTRACE_SIZE);
278 //xbt_libunwind_backtrace(mdp->heapinfo[block].busy_frag.bt[0],XBT_BACKTRACE_SIZE);
281 mdp -> heapstats.chunks_free += (BLOCKSIZE >> log) - 1;
282 mdp -> heapstats.bytes_free += BLOCKSIZE - (1 << log);
283 mdp -> heapstats.bytes_used -= BLOCKSIZE - (1 << log);
286 /* Large allocation to receive one or more blocks.
287 Search the free list in a circle starting at the last place visited.
288 If we loop completely around without finding a large enough
289 space we will have to get more memory from the system. */
290 size_t blocks = BLOCKIFY(size);
291 size_t start = MALLOC_SEARCH_START;
292 block = MALLOC_SEARCH_START;
293 while (mdp->heapinfo[block].free_block.size < blocks) {
294 if (mdp->heapinfo[block].type >=0) { // Don't trust xbt_die and friends in malloc-level library, you fool!
295 fprintf(stderr,"Internal error: found a free block not marked as such (block=%lu type=%lu). Please report this bug.\n",(unsigned long)block,(unsigned long)mdp->heapinfo[block].type);
299 block = mdp->heapinfo[block].free_block.next;
300 if (block == start) {
301 /* Need to get more from the system. Check to see if
302 the new core will be contiguous with the final free
303 block; if so we don't need to get as much. */
304 block = mdp->heapinfo[0].free_block.prev;
305 size_t lastblocks = mdp->heapinfo[block].free_block.size;
306 if (mdp->heaplimit != 0 &&
307 block + lastblocks == mdp->heaplimit &&
308 mmorecore(mdp, 0) == ADDRESS(block + lastblocks) &&
309 (register_morecore(mdp, (blocks - lastblocks) * BLOCKSIZE)) != NULL) {
310 /* Which block we are extending (the `final free
311 block' referred to above) might have changed, if
312 it got combined with a freed info table. */
313 block = mdp->heapinfo[0].free_block.prev;
315 mdp->heapinfo[block].free_block.size += (blocks - lastblocks);
318 result = register_morecore(mdp, blocks * BLOCKSIZE);
320 block = BLOCK(result);
321 mmalloc_mark_used(mdp, block, blocks, requested_size);
325 /* Need large block(s), but found some in the existing heap */
328 /* At this point we have found a suitable free list entry.
329 Figure out how to remove what we need from the list. */
330 result = ADDRESS(block);
331 if (mdp->heapinfo[block].free_block.size > blocks) {
332 /* The block we found has a bit left over,
333 so relink the tail end back into the free list. */
334 mdp->heapinfo[block + blocks].free_block.size
335 = mdp->heapinfo[block].free_block.size - blocks;
336 mdp->heapinfo[block + blocks].free_block.next
337 = mdp->heapinfo[block].free_block.next;
338 mdp->heapinfo[block + blocks].free_block.prev
339 = mdp->heapinfo[block].free_block.prev;
340 mdp->heapinfo[mdp->heapinfo[block].free_block.prev].free_block.next
341 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev
342 = mdp->heapindex = block + blocks;
344 /* The block exactly matches our requirements,
345 so just remove it from the list. */
346 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev
347 = mdp->heapinfo[block].free_block.prev;
348 mdp->heapinfo[mdp->heapinfo[block].free_block.prev].free_block.next
349 = mdp->heapindex = mdp->heapinfo[block].free_block.next;
352 mmalloc_mark_used(mdp, block, blocks, requested_size);
353 mdp -> heapstats.bytes_free -= blocks * BLOCKSIZE;
356 //printf("(%s) Done mallocing. Result is %p\n",xbt_thread_self_name(),result);fflush(stdout);