1/*
2 * This module derived from code donated to the FreeBSD Project by
3 * Matthew Dillon <dillon@backplane.com>
4 *
5 * Copyright (c) 1998 The FreeBSD Project
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
16 *
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
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD$");
32
33/*
34 * LIB/MEMORY/ZALLOC.C	- self contained low-overhead memory pool/allocation
35 *			  subsystem
36 *
37 *	This subsystem implements memory pools and memory allocation
38 *	routines.
39 *
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.
44 *
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.
48 *
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
53 *	available.
54 *
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.
60 *
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().
67 *
68 *	Allocation and frees of 0 bytes are valid operations.
69 */
70
71#include "zalloc_defs.h"
72
73/*
74 * znalloc() -	allocate memory (without zeroing) from pool.  Call reclaim
75 *		and retry if appropriate, return NULL if unable to allocate
76 *		memory.
77 */
78
79void *
80znalloc(MemPool *mp, uintptr_t bytes)
81{
82    /*
83     * align according to pool object size (can be 0).  This is
84     * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
85     *
86     */
87    bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
88
89    if (bytes == 0)
90	return((void *)-1);
91
92    /*
93     * locate freelist entry big enough to hold the object.  If all objects
94     * are the same size, this is a constant-time function.
95     */
96
97    if (bytes <= mp->mp_Size - mp->mp_Used) {
98	MemNode **pmn;
99	MemNode *mn;
100
101	for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) {
102	    if (bytes > mn->mr_Bytes)
103		continue;
104
105	    /*
106	     *  Cut a chunk of memory out of the beginning of this
107	     *  block and fixup the link appropriately.
108	     */
109
110	    {
111		char *ptr = (char *)mn;
112
113		if (mn->mr_Bytes == bytes) {
114		    *pmn = mn->mr_Next;
115		} else {
116		    mn = (MemNode *)((char *)mn + bytes);
117		    mn->mr_Next  = ((MemNode *)ptr)->mr_Next;
118		    mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes;
119		    *pmn = mn;
120		}
121		mp->mp_Used += bytes;
122		return(ptr);
123	    }
124	}
125    }
126
127    /*
128     * Memory pool is full, return NULL.
129     */
130
131    return(NULL);
132}
133
134/*
135 * zfree() - free previously allocated memory
136 */
137
138void
139zfree(MemPool *mp, void *ptr, uintptr_t bytes)
140{
141    /*
142     * align according to pool object size (can be 0).  This is
143     * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
144     */
145    bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
146
147    if (bytes == 0)
148	return;
149
150    /*
151     * panic if illegal pointer
152     */
153
154    if ((char *)ptr < (char *)mp->mp_Base ||
155	(char *)ptr + bytes > (char *)mp->mp_End ||
156	((uintptr_t)ptr & MEMNODE_SIZE_MASK) != 0)
157	panic("zfree(%p,%ju): wild pointer", ptr, (uintmax_t)bytes);
158
159    /*
160     * free the segment
161     */
162
163    {
164	MemNode **pmn;
165	MemNode *mn;
166
167	mp->mp_Used -= bytes;
168
169	for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) {
170	    /*
171	     * If area between last node and current node
172	     *  - check range
173	     *  - check merge with next area
174	     *  - check merge with previous area
175	     */
176	    if ((char *)ptr <= (char *)mn) {
177		/*
178		 * range check
179		 */
180		if ((char *)ptr + bytes > (char *)mn) {
181		    panic("zfree(%p,%ju): corrupt memlist1", ptr,
182			(uintmax_t)bytes);
183		}
184
185		/*
186		 * merge against next area or create independant area
187		 */
188
189		if ((char *)ptr + bytes == (char *)mn) {
190		    ((MemNode *)ptr)->mr_Next = mn->mr_Next;
191		    ((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes;
192		} else {
193		    ((MemNode *)ptr)->mr_Next = mn;
194		    ((MemNode *)ptr)->mr_Bytes= bytes;
195		}
196		*pmn = mn = (MemNode *)ptr;
197
198		/*
199		 * merge against previous area (if there is a previous
200		 * area).
201		 */
202
203		if (pmn != &mp->mp_First) {
204		    if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) {
205			((MemNode *)pmn)->mr_Next = mn->mr_Next;
206			((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes;
207			mn = (MemNode *)pmn;
208		    }
209		}
210		return;
211		/* NOT REACHED */
212	    }
213	    if ((char *)ptr < (char *)mn + mn->mr_Bytes) {
214		panic("zfree(%p,%ju): corrupt memlist2", ptr,
215		    (uintmax_t)bytes);
216	    }
217	}
218	/*
219	 * We are beyond the last MemNode, append new MemNode.  Merge against
220	 * previous area if possible.
221	 */
222	if (pmn == &mp->mp_First ||
223	    (char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr
224	) {
225	    ((MemNode *)ptr)->mr_Next = NULL;
226	    ((MemNode *)ptr)->mr_Bytes = bytes;
227	    *pmn = (MemNode *)ptr;
228	    mn = (MemNode *)ptr;
229	} else {
230	    ((MemNode *)pmn)->mr_Bytes += bytes;
231	    mn = (MemNode *)pmn;
232	}
233    }
234}
235
236/*
237 * zextendPool() - extend memory pool to cover additional space.
238 *
239 *		   Note: the added memory starts out as allocated, you
240 *		   must free it to make it available to the memory subsystem.
241 *
242 *		   Note: mp_Size may not reflect (mp_End - mp_Base) range
243 *		   due to other parts of the system doing their own sbrk()
244 *		   calls.
245 */
246
247void
248zextendPool(MemPool *mp, void *base, uintptr_t bytes)
249{
250    if (mp->mp_Size == 0) {
251	mp->mp_Base = base;
252	mp->mp_Used = bytes;
253	mp->mp_End = (char *)base + bytes;
254	mp->mp_Size = bytes;
255    } else {
256	void *pend = (char *)mp->mp_Base + mp->mp_Size;
257
258	if (base < mp->mp_Base) {
259	    mp->mp_Size += (char *)mp->mp_Base - (char *)base;
260	    mp->mp_Used += (char *)mp->mp_Base - (char *)base;
261	    mp->mp_Base = base;
262	}
263	base = (char *)base + bytes;
264	if (base > pend) {
265	    mp->mp_Size += (char *)base - (char *)pend;
266	    mp->mp_Used += (char *)base - (char *)pend;
267	    mp->mp_End = (char *)base;
268	}
269    }
270}
271
272#ifdef ZALLOCDEBUG
273
274void
275zallocstats(MemPool *mp)
276{
277    int abytes = 0;
278    int hbytes = 0;
279    int fcount = 0;
280    MemNode *mn;
281
282    printf("%d bytes reserved", (int) mp->mp_Size);
283
284    mn = mp->mp_First;
285
286    if ((void *)mn != (void *)mp->mp_Base) {
287	abytes += (char *)mn - (char *)mp->mp_Base;
288    }
289
290    while (mn) {
291	if ((char *)mn + mn->mr_Bytes != mp->mp_End) {
292	    hbytes += mn->mr_Bytes;
293	    ++fcount;
294	}
295	if (mn->mr_Next)
296	    abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes);
297	mn = mn->mr_Next;
298    }
299    printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",
300	abytes,
301	fcount,
302	hbytes
303    );
304}
305
306#endif
307
308