1 /* 2 * Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org> 3 * Copyright (c) 2000-2001 Jason Evans <jasone@freebsd.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 * $FreeBSD: src/lib/libpthread/thread/thr_stack.c,v 1.9 2004/10/06 08:11:07 davidxu Exp $ 28 */ 29 #include <sys/types.h> 30 #include <sys/mman.h> 31 #include <sys/queue.h> 32 #include <sys/time.h> 33 #include <sys/resource.h> 34 #include <sys/sysctl.h> 35 #include <machine/tls.h> 36 #include <machine/vmparam.h> 37 #include <stdlib.h> 38 #include <pthread.h> 39 #include "thr_private.h" 40 41 /* Spare thread stack. */ 42 struct stack { 43 LIST_ENTRY(stack) qe; /* Stack queue linkage. */ 44 size_t stacksize; /* Stack size (rounded up). */ 45 size_t guardsize; /* Guard size. */ 46 void *stackaddr; /* Stack address. */ 47 }; 48 49 /* 50 * Default sized (stack and guard) spare stack queue. Stacks are cached 51 * to avoid additional complexity managing mmap()ed stack regions. Spare 52 * stacks are used in LIFO order to increase cache locality. 53 */ 54 static LIST_HEAD(, stack) dstackq = LIST_HEAD_INITIALIZER(dstackq); 55 56 /* 57 * Miscellaneous sized (non-default stack and/or guard) spare stack queue. 58 * Stacks are cached to avoid additional complexity managing mmap()ed 59 * stack regions. This list is unordered, since ordering on both stack 60 * size and guard size would be more trouble than it's worth. Stacks are 61 * allocated from this cache on a first size match basis. 62 */ 63 static LIST_HEAD(, stack) mstackq = LIST_HEAD_INITIALIZER(mstackq); 64 65 /* 66 * Thread stack base for mmap() hint, starts 67 * at _usrstack - kern.maxssiz - kern.maxthrssiz 68 */ 69 static char *base_stack = NULL; 70 71 /* 72 * Round size up to the nearest multiple of 73 * _thr_page_size. 74 */ 75 static inline size_t 76 round_up(size_t size) 77 { 78 if (size % _thr_page_size != 0) 79 size = ((size / _thr_page_size) + 1) * 80 _thr_page_size; 81 return size; 82 } 83 84 int 85 _thr_stack_alloc(pthread_attr_t attr) 86 { 87 pthread_t curthread = tls_get_curthread(); 88 struct stack *spare_stack; 89 size_t stacksize; 90 size_t guardsize; 91 char *stackaddr; 92 93 /* 94 * Round up stack size to nearest multiple of _thr_page_size so 95 * that mmap() * will work. If the stack size is not an even 96 * multiple, we end up initializing things such that there is 97 * unused space above the beginning of the stack, so the stack 98 * sits snugly against its guard. 99 */ 100 stacksize = round_up(attr->stacksize_attr); 101 guardsize = round_up(attr->guardsize_attr); 102 103 attr->stackaddr_attr = NULL; 104 attr->flags &= ~THR_STACK_USER; 105 106 /* 107 * Use the garbage collector lock for synchronization of the 108 * spare stack lists and allocations from usrstack. 109 */ 110 THREAD_LIST_LOCK(curthread); 111 /* 112 * If the stack and guard sizes are default, try to allocate a stack 113 * from the default-size stack cache: 114 */ 115 if ((stacksize == THR_STACK_DEFAULT) && 116 (guardsize == _thr_guard_default)) { 117 if ((spare_stack = LIST_FIRST(&dstackq)) != NULL) { 118 /* Use the spare stack. */ 119 LIST_REMOVE(spare_stack, qe); 120 attr->stackaddr_attr = spare_stack->stackaddr; 121 } 122 } 123 /* 124 * The user specified a non-default stack and/or guard size, so try to 125 * allocate a stack from the non-default size stack cache, using the 126 * rounded up stack size (stack_size) in the search: 127 */ 128 else { 129 LIST_FOREACH(spare_stack, &mstackq, qe) { 130 if (spare_stack->stacksize == stacksize && 131 spare_stack->guardsize == guardsize) { 132 LIST_REMOVE(spare_stack, qe); 133 attr->stackaddr_attr = spare_stack->stackaddr; 134 break; 135 } 136 } 137 } 138 if (attr->stackaddr_attr != NULL) { 139 /* A cached stack was found. Release the lock. */ 140 THREAD_LIST_UNLOCK(curthread); 141 } else { 142 /* 143 * Calculate base_stack on first use (race ok). 144 * If base _stack 145 */ 146 if (base_stack == NULL) { 147 int64_t maxssiz; 148 int64_t maxthrssiz; 149 struct rlimit rl; 150 size_t len; 151 152 if (getrlimit(RLIMIT_STACK, &rl) == 0) 153 maxssiz = rl.rlim_max; 154 else 155 maxssiz = MAXSSIZ; 156 len = sizeof(maxssiz); 157 sysctlbyname("kern.maxssiz", &maxssiz, &len, NULL, 0); 158 len = sizeof(maxthrssiz); 159 if (sysctlbyname("kern.maxthrssiz", 160 &maxthrssiz, &len, NULL, 0) < 0) { 161 maxthrssiz = MAXTHRSSIZ; 162 } 163 base_stack = _usrstack - maxssiz - maxthrssiz; 164 } 165 166 /* Release the lock before mmap'ing it. */ 167 THREAD_LIST_UNLOCK(curthread); 168 169 /* 170 * Map the stack and guard page together then split the 171 * guard page from allocated space. 172 * 173 * We no longer use MAP_STACK and we define an area far 174 * away from the default user stack (even though this will 175 * cost us another few 4K page-table pages). DFly no longer 176 * allows new MAP_STACK mappings to be made inside ungrown 177 * portions of existing mappings. 178 */ 179 stackaddr = mmap(base_stack, stacksize + guardsize, 180 PROT_READ | PROT_WRITE, 181 MAP_ANON | MAP_PRIVATE, -1, 0); 182 if (stackaddr != MAP_FAILED && guardsize) { 183 if (mmap(stackaddr, guardsize, 0, 184 MAP_ANON | MAP_FIXED, -1, 0) == MAP_FAILED) { 185 munmap(stackaddr, stacksize + guardsize); 186 stackaddr = MAP_FAILED; 187 } else { 188 stackaddr += guardsize; 189 } 190 } 191 if (stackaddr == MAP_FAILED) 192 stackaddr = NULL; 193 attr->stackaddr_attr = stackaddr; 194 } 195 if (attr->stackaddr_attr != NULL) 196 return (0); 197 else 198 return (-1); 199 } 200 201 /* This function must be called with _thread_list_lock held. */ 202 void 203 _thr_stack_free(pthread_attr_t attr) 204 { 205 struct stack *spare_stack; 206 207 if ((attr != NULL) && ((attr->flags & THR_STACK_USER) == 0) 208 && (attr->stackaddr_attr != NULL)) { 209 spare_stack = (struct stack *)((char *)attr->stackaddr_attr + 210 attr->stacksize_attr - sizeof(struct stack)); 211 spare_stack->stacksize = round_up(attr->stacksize_attr); 212 spare_stack->guardsize = round_up(attr->guardsize_attr); 213 spare_stack->stackaddr = attr->stackaddr_attr; 214 215 if (spare_stack->stacksize == THR_STACK_DEFAULT && 216 spare_stack->guardsize == _thr_guard_default) { 217 /* Default stack/guard size. */ 218 LIST_INSERT_HEAD(&dstackq, spare_stack, qe); 219 } else { 220 /* Non-default stack/guard size. */ 221 LIST_INSERT_HEAD(&mstackq, spare_stack, qe); 222 } 223 attr->stackaddr_attr = NULL; 224 } 225 } 226 227 void 228 _thr_stack_cleanup(void) 229 { 230 struct stack *spare; 231 232 while ((spare = LIST_FIRST(&dstackq)) != NULL) { 233 LIST_REMOVE(spare, qe); 234 munmap(spare->stackaddr, 235 spare->stacksize + spare->guardsize); 236 } 237 } 238