1 /* Memory allocator `malloc'. */
3 /* Copyright (c) 2010-2019. 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 /** Initialize 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 /* Initialize 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->heapstats.chunks_used++;
180 mdp->heapstats.bytes_used += nblocks * BLOCKSIZE;
183 /* Splitting mmalloc this way is mandated by a trick in mrealloc, that gives
184 back the memory of big blocks to the system before reallocating them: we don't
185 want to loose the beginning of the area when this happens */
186 void *mmalloc_no_memset(xbt_mheap_t mdp, size_t size)
191 size_t requested_size = size; // The amount of memory requested by user, for real
193 /* Work even if the user was stupid enough to ask a ridiculously small block (even 0-length),
194 * ie return a valid block that can be realloced and freed.
195 * glibc malloc does not use this trick but return a constant pointer, but we need to enlist the free fragments later on.
197 if (size < SMALLEST_POSSIBLE_MALLOC)
198 size = SMALLEST_POSSIBLE_MALLOC;
200 if (!(mdp->flags & MMALLOC_INITIALIZED))
203 /* Determine the allocation policy based on the request size. */
204 if (size <= BLOCKSIZE / 2) {
205 /* Small allocation to receive a fragment of a block.
206 Determine the logarithm to base two of the fragment size. */
209 while ((size /= 2) != 0) {
213 /* Look in the fragment lists for a free fragment of the desired size. */
214 if (xbt_swag_size(&mdp->fraghead[log])>0) {
215 /* There are free fragments of this size; Get one of them and prepare to return it.
216 Update the block's nfree and if no other free fragment, get out of the swag. */
218 /* search a fragment that I could return as a result */
219 malloc_info *candidate_info = xbt_swag_getFirst(&mdp->fraghead[log]);
220 size_t candidate_block = (candidate_info - &(mdp->heapinfo[0]));
221 size_t candidate_frag;
222 for (candidate_frag=0;candidate_frag<(size_t) (BLOCKSIZE >> log);candidate_frag++)
223 if (candidate_info->busy_frag.frag_size[candidate_frag] == -1)
225 xbt_assert(candidate_frag < (size_t) (BLOCKSIZE >> log),
226 "Block %zu was registered as containing free fragments of type %zu, but I can't find any",candidate_block,log);
228 result = (void*) (((char*)ADDRESS(candidate_block)) + (candidate_frag << log));
230 /* Remove this fragment from the list of free guys */
231 candidate_info->busy_frag.nfree--;
232 if (candidate_info->busy_frag.nfree == 0) {
233 xbt_swag_remove(candidate_info,&mdp->fraghead[log]);
236 /* Update our metadata about this fragment */
237 candidate_info->busy_frag.frag_size[candidate_frag] = requested_size;
238 candidate_info->busy_frag.ignore[candidate_frag] = 0;
240 /* Update the statistics. */
241 mdp -> heapstats.chunks_used++;
242 mdp -> heapstats.bytes_used += 1 << log;
243 mdp -> heapstats.chunks_free--;
244 mdp -> heapstats.bytes_free -= 1 << log;
247 /* No free fragments of the desired size, so get a new block
248 and break it into fragments, returning the first. */
250 result = mmalloc(mdp, BLOCKSIZE); // does not return NULL
251 block = BLOCK(result);
253 mdp->heapinfo[block].type = log;
254 /* Link all fragments but the first as free, and add the block to the swag of blocks containing free frags */
256 for (i = 1; i < (size_t) (BLOCKSIZE >> log); ++i) {
257 mdp->heapinfo[block].busy_frag.frag_size[i] = -1;
258 mdp->heapinfo[block].busy_frag.ignore[i] = 0;
260 mdp->heapinfo[block].busy_frag.nfree = i - 1;
261 mdp->heapinfo[block].freehook.prev = NULL;
262 mdp->heapinfo[block].freehook.next = NULL;
264 xbt_swag_insert(&mdp->heapinfo[block], &(mdp->fraghead[log]));
266 /* mark the fragment returned as busy */
267 mdp->heapinfo[block].busy_frag.frag_size[0] = requested_size;
268 mdp->heapinfo[block].busy_frag.ignore[0] = 0;
271 mdp -> heapstats.chunks_free += (BLOCKSIZE >> log) - 1;
272 mdp -> heapstats.bytes_free += BLOCKSIZE - (1 << log);
273 mdp -> heapstats.bytes_used -= BLOCKSIZE - (1 << log);
276 /* Large allocation to receive one or more blocks.
277 Search the free list in a circle starting at the last place visited.
278 If we loop completely around without finding a large enough
279 space we will have to get more memory from the system. */
280 size_t blocks = BLOCKIFY(size);
281 size_t start = MALLOC_SEARCH_START;
282 block = MALLOC_SEARCH_START;
283 while (mdp->heapinfo[block].free_block.size < blocks) {
284 if (mdp->heapinfo[block].type >=0) { // Don't trust xbt_die and friends in malloc-level library, you fool!
285 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);
289 block = mdp->heapinfo[block].free_block.next;
290 if (block == start) {
291 /* Need to get more from the system. Check to see if
292 the new core will be contiguous with the final free
293 block; if so we don't need to get as much. */
294 block = mdp->heapinfo[0].free_block.prev;
295 size_t lastblocks = mdp->heapinfo[block].free_block.size;
296 if (mdp->heaplimit != 0 &&
297 block + lastblocks == mdp->heaplimit &&
298 mmorecore(mdp, 0) == ADDRESS(block + lastblocks) &&
299 (register_morecore(mdp, (blocks - lastblocks) * BLOCKSIZE)) != NULL) {
300 /* Which block we are extending (the `final free
301 block' referred to above) might have changed, if
302 it got combined with a freed info table. */
303 block = mdp->heapinfo[0].free_block.prev;
305 mdp->heapinfo[block].free_block.size += (blocks - lastblocks);
308 result = register_morecore(mdp, blocks * BLOCKSIZE);
310 block = BLOCK(result);
311 mmalloc_mark_used(mdp, block, blocks, requested_size);
315 /* Need large block(s), but found some in the existing heap */
318 /* At this point we have found a suitable free list entry.
319 Figure out how to remove what we need from the list. */
320 result = ADDRESS(block);
321 if (mdp->heapinfo[block].free_block.size > blocks) {
322 /* The block we found has a bit left over,
323 so relink the tail end back into the free list. */
324 mdp->heapinfo[block + blocks].free_block.size
325 = mdp->heapinfo[block].free_block.size - blocks;
326 mdp->heapinfo[block + blocks].free_block.next
327 = mdp->heapinfo[block].free_block.next;
328 mdp->heapinfo[block + blocks].free_block.prev
329 = mdp->heapinfo[block].free_block.prev;
330 mdp->heapinfo[mdp->heapinfo[block].free_block.prev].free_block.next
331 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev
332 = mdp->heapindex = block + blocks;
334 /* The block exactly matches our requirements,
335 so just remove it from the list. */
336 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev
337 = mdp->heapinfo[block].free_block.prev;
338 mdp->heapinfo[mdp->heapinfo[block].free_block.prev].free_block.next
339 = mdp->heapindex = mdp->heapinfo[block].free_block.next;
342 mmalloc_mark_used(mdp, block, blocks, requested_size);
343 mdp -> heapstats.bytes_free -= blocks * BLOCKSIZE;