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 * Objects in the pool must be aligned to at least the size of struct MemNode. 75 * They must also be aligned to MALLOCALIGN, which should normally be larger 76 * than the struct, so assert that to be so at compile time. 77 */ 78 typedef char assert_align[(sizeof(struct MemNode) <= MALLOCALIGN) ? 1 : -1]; 79 80 #define MEMNODE_SIZE_MASK MALLOCALIGN_MASK 81 82 /* 83 * znalloc() - allocate memory (without zeroing) from pool. Call reclaim 84 * and retry if appropriate, return NULL if unable to allocate 85 * memory. 86 */ 87 88 void * 89 znalloc(MemPool *mp, uintptr_t bytes) 90 { 91 /* 92 * align according to pool object size (can be 0). This is 93 * inclusive of the MEMNODE_SIZE_MASK minimum alignment. 94 * 95 */ 96 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK; 97 98 if (bytes == 0) 99 return((void *)-1); 100 101 /* 102 * locate freelist entry big enough to hold the object. If all objects 103 * are the same size, this is a constant-time function. 104 */ 105 106 if (bytes <= mp->mp_Size - mp->mp_Used) { 107 MemNode **pmn; 108 MemNode *mn; 109 110 for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) { 111 if (bytes > mn->mr_Bytes) 112 continue; 113 114 /* 115 * Cut a chunk of memory out of the beginning of this 116 * block and fixup the link appropriately. 117 */ 118 119 { 120 char *ptr = (char *)mn; 121 122 if (mn->mr_Bytes == bytes) { 123 *pmn = mn->mr_Next; 124 } else { 125 mn = (MemNode *)((char *)mn + bytes); 126 mn->mr_Next = ((MemNode *)ptr)->mr_Next; 127 mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes; 128 *pmn = mn; 129 } 130 mp->mp_Used += bytes; 131 return(ptr); 132 } 133 } 134 } 135 136 /* 137 * Memory pool is full, return NULL. 138 */ 139 140 return(NULL); 141 } 142 143 /* 144 * zfree() - free previously allocated memory 145 */ 146 147 void 148 zfree(MemPool *mp, void *ptr, uintptr_t bytes) 149 { 150 /* 151 * align according to pool object size (can be 0). This is 152 * inclusive of the MEMNODE_SIZE_MASK minimum alignment. 153 */ 154 bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK; 155 156 if (bytes == 0) 157 return; 158 159 /* 160 * panic if illegal pointer 161 */ 162 163 if ((char *)ptr < (char *)mp->mp_Base || 164 (char *)ptr + bytes > (char *)mp->mp_End || 165 ((uintptr_t)ptr & MEMNODE_SIZE_MASK) != 0) 166 panic("zfree(%p,%ju): wild pointer", ptr, (uintmax_t)bytes); 167 168 /* 169 * free the segment 170 */ 171 172 { 173 MemNode **pmn; 174 MemNode *mn; 175 176 mp->mp_Used -= bytes; 177 178 for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) { 179 /* 180 * If area between last node and current node 181 * - check range 182 * - check merge with next area 183 * - check merge with previous area 184 */ 185 if ((char *)ptr <= (char *)mn) { 186 /* 187 * range check 188 */ 189 if ((char *)ptr + bytes > (char *)mn) { 190 panic("zfree(%p,%ju): corrupt memlist1", ptr, 191 (uintmax_t)bytes); 192 } 193 194 /* 195 * merge against next area or create independant area 196 */ 197 198 if ((char *)ptr + bytes == (char *)mn) { 199 ((MemNode *)ptr)->mr_Next = mn->mr_Next; 200 ((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes; 201 } else { 202 ((MemNode *)ptr)->mr_Next = mn; 203 ((MemNode *)ptr)->mr_Bytes= bytes; 204 } 205 *pmn = mn = (MemNode *)ptr; 206 207 /* 208 * merge against previous area (if there is a previous 209 * area). 210 */ 211 212 if (pmn != &mp->mp_First) { 213 if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) { 214 ((MemNode *)pmn)->mr_Next = mn->mr_Next; 215 ((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes; 216 mn = (MemNode *)pmn; 217 } 218 } 219 return; 220 /* NOT REACHED */ 221 } 222 if ((char *)ptr < (char *)mn + mn->mr_Bytes) { 223 panic("zfree(%p,%ju): corrupt memlist2", ptr, 224 (uintmax_t)bytes); 225 } 226 } 227 /* 228 * We are beyond the last MemNode, append new MemNode. Merge against 229 * previous area if possible. 230 */ 231 if (pmn == &mp->mp_First || 232 (char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr 233 ) { 234 ((MemNode *)ptr)->mr_Next = NULL; 235 ((MemNode *)ptr)->mr_Bytes = bytes; 236 *pmn = (MemNode *)ptr; 237 mn = (MemNode *)ptr; 238 } else { 239 ((MemNode *)pmn)->mr_Bytes += bytes; 240 mn = (MemNode *)pmn; 241 } 242 } 243 } 244 245 /* 246 * zextendPool() - extend memory pool to cover additional space. 247 * 248 * Note: the added memory starts out as allocated, you 249 * must free it to make it available to the memory subsystem. 250 * 251 * Note: mp_Size may not reflect (mp_End - mp_Base) range 252 * due to other parts of the system doing their own sbrk() 253 * calls. 254 */ 255 256 void 257 zextendPool(MemPool *mp, void *base, uintptr_t bytes) 258 { 259 if (mp->mp_Size == 0) { 260 mp->mp_Base = base; 261 mp->mp_Used = bytes; 262 mp->mp_End = (char *)base + bytes; 263 mp->mp_Size = bytes; 264 } else { 265 void *pend = (char *)mp->mp_Base + mp->mp_Size; 266 267 if (base < mp->mp_Base) { 268 mp->mp_Size += (char *)mp->mp_Base - (char *)base; 269 mp->mp_Used += (char *)mp->mp_Base - (char *)base; 270 mp->mp_Base = base; 271 } 272 base = (char *)base + bytes; 273 if (base > pend) { 274 mp->mp_Size += (char *)base - (char *)pend; 275 mp->mp_Used += (char *)base - (char *)pend; 276 mp->mp_End = (char *)base; 277 } 278 } 279 } 280 281 #ifdef ZALLOCDEBUG 282 283 void 284 zallocstats(MemPool *mp) 285 { 286 int abytes = 0; 287 int hbytes = 0; 288 int fcount = 0; 289 MemNode *mn; 290 291 printf("%d bytes reserved", (int) mp->mp_Size); 292 293 mn = mp->mp_First; 294 295 if ((void *)mn != (void *)mp->mp_Base) { 296 abytes += (char *)mn - (char *)mp->mp_Base; 297 } 298 299 while (mn) { 300 if ((char *)mn + mn->mr_Bytes != mp->mp_End) { 301 hbytes += mn->mr_Bytes; 302 ++fcount; 303 } 304 if (mn->mr_Next) 305 abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes); 306 mn = mn->mr_Next; 307 } 308 printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n", 309 abytes, 310 fcount, 311 hbytes 312 ); 313 } 314 315 #endif 316 317