2 * This module derived from code donated to the FreeBSD Project by
3 * Matthew Dillon <dillon@backplane.com>
5 * Copyright (c) 1998 The FreeBSD Project
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * $FreeBSD: src/lib/libstand/zalloc.c,v 1.5.2.1 2002/12/28 18:04:15 dillon Exp $
33 * LIB/MEMORY/ZALLOC.C - self contained low-overhead memory pool/allocation
36 * This subsystem implements memory pools and memory allocation
39 * Pools are managed via a linked list of 'free' areas. Allocating
40 * memory creates holes in the freelist, freeing memory fills them.
41 * Since the freelist consists only of free memory areas, it is possible
42 * to allocate the entire pool without incuring any structural overhead.
44 * The system works best when allocating similarly-sized chunks of
45 * memory. Care must be taken to avoid fragmentation when
46 * allocating/deallocating dissimilar chunks.
48 * When a memory pool is first allocated, the entire pool is marked as
49 * allocated. This is done mainly because we do not want to modify any
50 * portion of a pool's data area until we are given permission. The
51 * caller must explicitly deallocate portions of the pool to make them
54 * z[n]xalloc() works like z[n]alloc() but the allocation is made from
55 * within the specified address range. If the segment could not be
56 * allocated, NULL is returned. WARNING! The address range will be
57 * aligned to an 8 or 16 byte boundry depending on the cpu so if you
58 * give an unaligned address range, unexpected results may occur.
60 * If a standard allocation fails, the reclaim function will be called
61 * to recover some space. This usually causes other portions of the
62 * same pool to be released. Memory allocations at this low level
63 * should not block but you can do that too in your reclaim function
64 * if you want. Reclaim does not function when z[n]xalloc() is used,
65 * only for z[n]alloc().
67 * Allocation and frees of 0 bytes are valid operations.
70 #include "zalloc_defs.h"
73 * znalloc() - allocate memory (without zeroing) from pool. Call reclaim
74 * and retry if appropriate, return NULL if unable to allocate
79 znalloc(MemPool *mp, iaddr_t bytes)
82 * align according to pool object size (can be 0). This is
83 * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
86 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
92 * locate freelist entry big enough to hold the object. If all objects
93 * are the same size, this is a constant-time function.
96 if (bytes <= mp->mp_Size - mp->mp_Used) {
100 for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) {
101 if (bytes > mn->mr_Bytes)
105 * Cut a chunk of memory out of the beginning of this
106 * block and fixup the link appropriately.
110 char *ptr = (char *)mn;
112 if (mn->mr_Bytes == bytes) {
115 mn = (MemNode *)((char *)mn + bytes);
116 mn->mr_Next = ((MemNode *)ptr)->mr_Next;
117 mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes;
120 mp->mp_Used += bytes;
127 * Memory pool is full, return NULL.
134 * zfree() - free previously allocated memory
138 zfree(MemPool *mp, void *ptr, iaddr_t bytes)
141 * align according to pool object size (can be 0). This is
142 * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
144 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
150 * panic if illegal pointer
153 if ((char *)ptr < (char *)mp->mp_Base ||
154 (char *)ptr + bytes > (char *)mp->mp_End ||
155 ((iaddr_t)ptr & MEMNODE_SIZE_MASK) != 0)
156 panic("zfree(%p,%d): wild pointer", ptr, bytes);
166 mp->mp_Used -= bytes;
168 for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) {
170 * If area between last node and current node
172 * - check merge with next area
173 * - check merge with previous area
175 if ((char *)ptr <= (char *)mn) {
179 if ((char *)ptr + bytes > (char *)mn)
180 panic("zfree(%p,%d): corrupt memlist1",ptr, bytes);
183 * merge against next area or create independant area
186 if ((char *)ptr + bytes == (char *)mn) {
187 ((MemNode *)ptr)->mr_Next = mn->mr_Next;
188 ((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes;
190 ((MemNode *)ptr)->mr_Next = mn;
191 ((MemNode *)ptr)->mr_Bytes= bytes;
193 *pmn = mn = (MemNode *)ptr;
196 * merge against previous area (if there is a previous
200 if (pmn != &mp->mp_First) {
201 if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) {
202 ((MemNode *)pmn)->mr_Next = mn->mr_Next;
203 ((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes;
210 if ((char *)ptr < (char *)mn + mn->mr_Bytes)
211 panic("zfree(%p,%d): corrupt memlist2", ptr, bytes);
214 * We are beyond the last MemNode, append new MemNode. Merge against
215 * previous area if possible.
217 if (pmn == &mp->mp_First ||
218 (char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr
220 ((MemNode *)ptr)->mr_Next = NULL;
221 ((MemNode *)ptr)->mr_Bytes = bytes;
222 *pmn = (MemNode *)ptr;
225 ((MemNode *)pmn)->mr_Bytes += bytes;
232 * zextendPool() - extend memory pool to cover additional space.
234 * Note: the added memory starts out as allocated, you
235 * must free it to make it available to the memory subsystem.
237 * Note: mp_Size may not reflect (mp_End - mp_Base) range
238 * due to other parts of the system doing their own sbrk()
243 zextendPool(MemPool *mp, void *base, iaddr_t bytes)
245 if (mp->mp_Size == 0) {
248 mp->mp_End = (char *)base + bytes;
251 void *pend = (char *)mp->mp_Base + mp->mp_Size;
253 if (base < mp->mp_Base) {
254 mp->mp_Size += (char *)mp->mp_Base - (char *)base;
255 mp->mp_Used += (char *)mp->mp_Base - (char *)base;
258 base = (char *)base + bytes;
260 mp->mp_Size += (char *)base - (char *)pend;
261 mp->mp_Used += (char *)base - (char *)pend;
262 mp->mp_End = (char *)base;
270 zallocstats(MemPool *mp)
277 printf("%d bytes reserved", (int) mp->mp_Size);
281 if ((void *)mn != (void *)mp->mp_Base) {
282 abytes += (char *)mn - (char *)mp->mp_Base;
286 if ((char *)mn + mn->mr_Bytes != mp->mp_End) {
287 hbytes += mn->mr_Bytes;
291 abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes);
294 printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",