1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * The structure of the sbrk backend: 31 * 32 * +-----------+ 33 * | sbrk_top | 34 * +-----------+ 35 * | (vmem_sbrk_alloc(), vmem_free()) 36 * | 37 * +-----------+ 38 * | sbrk_heap | 39 * +-----------+ 40 * | | ... | (vmem_alloc(), vmem_free()) 41 * <other arenas> 42 * 43 * The sbrk_top arena holds all controlled memory. vmem_sbrk_alloc() handles 44 * allocations from it, including growing the heap when we run low. 45 * 46 * Growing the heap is complicated by the fact that we have to extend the 47 * sbrk_top arena (using _vmem_extend_alloc()), and that can fail. Since 48 * other threads may be actively allocating, we can't return the memory. 49 * 50 * Instead, we put it on a doubly-linked list, sbrk_fails, which we search 51 * before calling sbrk(). 52 */ 53 54 #include <errno.h> 55 #include <limits.h> 56 #include <sys/sysmacros.h> 57 #include <sys/mman.h> 58 #include <unistd.h> 59 60 #include "vmem_base.h" 61 62 #include "misc.h" 63 64 size_t vmem_sbrk_pagesize = 0; /* the preferred page size of the heap */ 65 66 #define VMEM_SBRK_MINALLOC (64 * 1024) 67 size_t vmem_sbrk_minalloc = VMEM_SBRK_MINALLOC; /* minimum allocation */ 68 69 static size_t real_pagesize; 70 static vmem_t *sbrk_heap; 71 72 typedef struct sbrk_fail { 73 struct sbrk_fail *sf_next; 74 struct sbrk_fail *sf_prev; 75 void *sf_base; /* == the sbrk_fail's address */ 76 size_t sf_size; /* the size of this buffer */ 77 } sbrk_fail_t; 78 79 static sbrk_fail_t sbrk_fails = { 80 &sbrk_fails, 81 &sbrk_fails, 82 NULL, 83 0 84 }; 85 86 static mutex_t sbrk_faillock = DEFAULTMUTEX; 87 88 /* 89 * Try to extend src with [pos, pos + size). 90 * 91 * If it fails, add the block to the sbrk_fails list. 92 */ 93 static void * 94 vmem_sbrk_extend_alloc(vmem_t *src, void *pos, size_t size, size_t alloc, 95 int vmflags) 96 { 97 sbrk_fail_t *fnext, *fprev, *fp; 98 void *ret; 99 100 ret = _vmem_extend_alloc(src, pos, size, alloc, vmflags); 101 if (ret != NULL) 102 return (ret); 103 104 fp = (sbrk_fail_t *)pos; 105 106 ASSERT(sizeof (sbrk_fail_t) <= size); 107 108 fp->sf_base = pos; 109 fp->sf_size = size; 110 111 (void) mutex_lock(&sbrk_faillock); 112 fp->sf_next = fnext = &sbrk_fails; 113 fp->sf_prev = fprev = sbrk_fails.sf_prev; 114 fnext->sf_prev = fp; 115 fprev->sf_next = fp; 116 (void) mutex_unlock(&sbrk_faillock); 117 118 return (NULL); 119 } 120 121 /* 122 * Try to add at least size bytes to src, using the sbrk_fails list 123 */ 124 static void * 125 vmem_sbrk_tryfail(vmem_t *src, size_t size, int vmflags) 126 { 127 sbrk_fail_t *fp; 128 129 (void) mutex_lock(&sbrk_faillock); 130 for (fp = sbrk_fails.sf_next; fp != &sbrk_fails; fp = fp->sf_next) { 131 if (fp->sf_size >= size) { 132 fp->sf_next->sf_prev = fp->sf_prev; 133 fp->sf_prev->sf_next = fp->sf_next; 134 fp->sf_next = fp->sf_prev = NULL; 135 break; 136 } 137 } 138 (void) mutex_unlock(&sbrk_faillock); 139 140 if (fp != &sbrk_fails) { 141 ASSERT(fp->sf_base == (void *)fp); 142 return (vmem_sbrk_extend_alloc(src, fp, fp->sf_size, size, 143 vmflags)); 144 } 145 /* 146 * nothing of the right size on the freelist 147 */ 148 return (NULL); 149 } 150 151 static void * 152 vmem_sbrk_alloc(vmem_t *src, size_t size, int vmflags) 153 { 154 extern void *_sbrk_grow_aligned(size_t min_size, size_t low_align, 155 size_t high_align, size_t *actual_size); 156 157 void *ret; 158 void *buf; 159 size_t buf_size; 160 161 int old_errno = errno; 162 163 ret = vmem_alloc(src, size, VM_NOSLEEP); 164 if (ret != NULL) { 165 errno = old_errno; 166 return (ret); 167 } 168 169 /* 170 * The allocation failed. We need to grow the heap. 171 * 172 * First, try to use any buffers which failed earlier. 173 */ 174 if (sbrk_fails.sf_next != &sbrk_fails && 175 (ret = vmem_sbrk_tryfail(src, size, vmflags)) != NULL) 176 return (ret); 177 178 buf_size = MAX(size, vmem_sbrk_minalloc); 179 180 /* 181 * buf_size gets overwritten with the actual allocated size 182 */ 183 buf = _sbrk_grow_aligned(buf_size, real_pagesize, vmem_sbrk_pagesize, 184 &buf_size); 185 186 if (buf != MAP_FAILED) { 187 ret = vmem_sbrk_extend_alloc(src, buf, buf_size, size, vmflags); 188 if (ret != NULL) { 189 errno = old_errno; 190 return (ret); 191 } 192 } 193 194 /* 195 * Growing the heap failed. The vmem_alloc() above called umem_reap(). 196 */ 197 ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP); 198 199 errno = old_errno; 200 return (NULL); 201 } 202 203 /* 204 * fork1() support 205 */ 206 void 207 vmem_sbrk_lockup(void) 208 { 209 (void) mutex_lock(&sbrk_faillock); 210 } 211 212 void 213 vmem_sbrk_release(void) 214 { 215 (void) mutex_unlock(&sbrk_faillock); 216 } 217 218 vmem_t * 219 vmem_sbrk_arena(vmem_alloc_t **a_out, vmem_free_t **f_out) 220 { 221 if (sbrk_heap == NULL) { 222 size_t heap_size; 223 224 real_pagesize = sysconf(_SC_PAGESIZE); 225 226 heap_size = vmem_sbrk_pagesize; 227 228 if (issetugid()) { 229 heap_size = 0; 230 } else if (heap_size != 0 && !ISP2(heap_size)) { 231 heap_size = 0; 232 log_message("ignoring bad pagesize: 0x%p\n", heap_size); 233 } 234 if (heap_size <= real_pagesize) { 235 heap_size = real_pagesize; 236 } else { 237 struct memcntl_mha mha; 238 mha.mha_cmd = MHA_MAPSIZE_BSSBRK; 239 mha.mha_flags = 0; 240 mha.mha_pagesize = heap_size; 241 242 if (memcntl(NULL, 0, MC_HAT_ADVISE, (char *)&mha, 0, 0) 243 == -1) { 244 log_message("unable to set MAPSIZE_BSSBRK to " 245 "0x%p\n", heap_size); 246 heap_size = real_pagesize; 247 } 248 } 249 vmem_sbrk_pagesize = heap_size; 250 251 /* validate vmem_sbrk_minalloc */ 252 if (vmem_sbrk_minalloc < VMEM_SBRK_MINALLOC) 253 vmem_sbrk_minalloc = VMEM_SBRK_MINALLOC; 254 vmem_sbrk_minalloc = P2ROUNDUP(vmem_sbrk_minalloc, heap_size); 255 256 sbrk_heap = vmem_init("sbrk_top", real_pagesize, 257 vmem_sbrk_alloc, vmem_free, 258 "sbrk_heap", NULL, 0, real_pagesize, 259 vmem_alloc, vmem_free); 260 } 261 262 if (a_out != NULL) 263 *a_out = vmem_alloc; 264 if (f_out != NULL) 265 *f_out = vmem_free; 266 267 return (sbrk_heap); 268 } 269