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
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
34 * LIB/MEMORY/ZALLOC.C - self contained low-overhead memory pool/allocation
37 * This subsystem implements memory pools and memory allocation
40 * Pools are managed via a linked list of 'free' areas. Allocating
41 * memory creates holes in the freelist, freeing memory fills them.
42 * Since the freelist consists only of free memory areas, it is possible
43 * to allocate the entire pool without incuring any structural overhead.
45 * The system works best when allocating similarly-sized chunks of
46 * memory. Care must be taken to avoid fragmentation when
47 * allocating/deallocating dissimilar chunks.
49 * When a memory pool is first allocated, the entire pool is marked as
50 * allocated. This is done mainly because we do not want to modify any
51 * portion of a pool's data area until we are given permission. The
52 * caller must explicitly deallocate portions of the pool to make them
55 * z[n]xalloc() works like z[n]alloc() but the allocation is made from
56 * within the specified address range. If the segment could not be
57 * allocated, NULL is returned. WARNING! The address range will be
58 * aligned to an 8 or 16 byte boundry depending on the cpu so if you
59 * give an unaligned address range, unexpected results may occur.
61 * If a standard allocation fails, the reclaim function will be called
62 * to recover some space. This usually causes other portions of the
63 * same pool to be released. Memory allocations at this low level
64 * should not block but you can do that too in your reclaim function
65 * if you want. Reclaim does not function when z[n]xalloc() is used,
66 * only for z[n]alloc().
68 * Allocation and frees of 0 bytes are valid operations.
71 #include "zalloc_defs.h"
74 * znalloc() - allocate memory (without zeroing) from pool. Call reclaim
75 * and retry if appropriate, return NULL if unable to allocate
80 znalloc(MemPool *mp, iaddr_t bytes)
83 * align according to pool object size (can be 0). This is
84 * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
87 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
93 * locate freelist entry big enough to hold the object. If all objects
94 * are the same size, this is a constant-time function.
97 if (bytes <= mp->mp_Size - mp->mp_Used) {
101 for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) {
102 if (bytes > mn->mr_Bytes)
106 * Cut a chunk of memory out of the beginning of this
107 * block and fixup the link appropriately.
111 char *ptr = (char *)mn;
113 if (mn->mr_Bytes == bytes) {
116 mn = (MemNode *)((char *)mn + bytes);
117 mn->mr_Next = ((MemNode *)ptr)->mr_Next;
118 mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes;
121 mp->mp_Used += bytes;
128 * Memory pool is full, return NULL.
135 * zfree() - free previously allocated memory
139 zfree(MemPool *mp, void *ptr, iaddr_t bytes)
142 * align according to pool object size (can be 0). This is
143 * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
145 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
151 * panic if illegal pointer
154 if ((char *)ptr < (char *)mp->mp_Base ||
155 (char *)ptr + bytes > (char *)mp->mp_End ||
156 ((iaddr_t)ptr & MEMNODE_SIZE_MASK) != 0)
157 panic("zfree(%p,%d): wild pointer", ptr, bytes);
167 mp->mp_Used -= bytes;
169 for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) {
171 * If area between last node and current node
173 * - check merge with next area
174 * - check merge with previous area
176 if ((char *)ptr <= (char *)mn) {
180 if ((char *)ptr + bytes > (char *)mn)
181 panic("zfree(%p,%d): corrupt memlist1",ptr, bytes);
184 * merge against next area or create independant area
187 if ((char *)ptr + bytes == (char *)mn) {
188 ((MemNode *)ptr)->mr_Next = mn->mr_Next;
189 ((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes;
191 ((MemNode *)ptr)->mr_Next = mn;
192 ((MemNode *)ptr)->mr_Bytes= bytes;
194 *pmn = mn = (MemNode *)ptr;
197 * merge against previous area (if there is a previous
201 if (pmn != &mp->mp_First) {
202 if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) {
203 ((MemNode *)pmn)->mr_Next = mn->mr_Next;
204 ((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes;
211 if ((char *)ptr < (char *)mn + mn->mr_Bytes)
212 panic("zfree(%p,%d): corrupt memlist2", ptr, bytes);
215 * We are beyond the last MemNode, append new MemNode. Merge against
216 * previous area if possible.
218 if (pmn == &mp->mp_First ||
219 (char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr
221 ((MemNode *)ptr)->mr_Next = NULL;
222 ((MemNode *)ptr)->mr_Bytes = bytes;
223 *pmn = (MemNode *)ptr;
226 ((MemNode *)pmn)->mr_Bytes += bytes;
233 * zextendPool() - extend memory pool to cover additional space.
235 * Note: the added memory starts out as allocated, you
236 * must free it to make it available to the memory subsystem.
238 * Note: mp_Size may not reflect (mp_End - mp_Base) range
239 * due to other parts of the system doing their own sbrk()
244 zextendPool(MemPool *mp, void *base, iaddr_t bytes)
246 if (mp->mp_Size == 0) {
249 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;
265 mp->mp_Size += bytes;
271 zallocstats(MemPool *mp)
278 printf("%d bytes reserved", (int) mp->mp_Size);
282 if ((void *)mn != (void *)mp->mp_Base) {
283 abytes += (char *)mn - (char *)mp->mp_Base;
287 if ((char *)mn + mn->mr_Bytes != mp->mp_End) {
288 hbytes += mn->mr_Bytes;
292 abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes);
295 printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",