js/src/jsgcchunk.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=4 sw=4 et tw=99 ft=cpp:
   3  *
   4  * ***** BEGIN LICENSE BLOCK *****
   5  * Copyright (C) 2006-2008 Jason Evans <jasone@FreeBSD.org>.
   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(s), this list of conditions and the following disclaimer as
  13  *    the first lines of this file unmodified other than the possible
  14  *    addition of one or more copyright notices.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice(s), this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  21  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
  24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  27  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  28  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  29  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ***** END LICENSE BLOCK ***** */
  33
  34 #include <stdlib.h>
  35 #include "jstypes.h"
  36 #include "jsstdint.h"
  37 #include "jsgcchunk.h"
  38
  39 #ifdef XP_WIN
  40 # include "jswin.h"
  41
  42 # ifdef _MSC_VER
  43 #  pragma warning( disable: 4267 4996 4146 )
  44 # endif
  45
  46 #elif defined(XP_MACOSX) || defined(DARWIN)
  47
  48 # include <libkern/OSAtomic.h>
  49 # include <mach/mach_error.h>
  50 # include <mach/mach_init.h>
  51 # include <mach/vm_map.h>
  52 # include <malloc/malloc.h>
  53
  54 #elif defined(XP_UNIX) || defined(XP_BEOS)
  55
  56 # include <unistd.h>
  57 # include <sys/mman.h>
  58
  59 # ifndef MAP_NOSYNC
  60 #  define MAP_NOSYNC    0
  61 # endif
  62
  63 #endif
  64
  65 #ifdef XP_WIN
  66
  67 /*
  68  * On Windows CE < 6 we must use separated MEM_RESERVE and MEM_COMMIT
  69  * VirtualAlloc calls and we cannot use MEM_RESERVE to allocate at the given
  70  * address. So we use a workaround based on oversized allocation.
  71  */
  72 # if defined(WINCE) && !defined(MOZ_MEMORY_WINCE6)
  73
  74 #  define JS_GC_HAS_MAP_ALIGN
  75
  76 static void
  77 UnmapPagesAtBase(void *p)
  78 {
  79     JS_ALWAYS_TRUE(VirtualFree(p, 0, MEM_RELEASE));
  80 }
  81
  82 static void *
  83 MapAlignedPages(size_t size, size_t alignment)
  84 {
  85     JS_ASSERT(size % alignment == 0);
  86     JS_ASSERT(size >= alignment);
  87
  88     void *reserve = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
  89     if (!reserve)
  90         return NULL;
  91
  92     void *p = VirtualAlloc(reserve, size, MEM_COMMIT, PAGE_READWRITE);
  93     JS_ASSERT(p == reserve);
  94
  95     size_t mask = alignment - 1;
  96     size_t offset = (uintptr_t) p & mask;
  97     if (!offset)
  98         return p;
  99
 100     /* Try to extend the initial allocation. */
 101     UnmapPagesAtBase(reserve);
 102     reserve = VirtualAlloc(NULL, size + alignment - offset, MEM_RESERVE,
 103                            PAGE_NOACCESS);
 104     if (!reserve)
 105         return NULL;
 106     if (offset == ((uintptr_t) reserve & mask)) {
 107         void *aligned = (void *) ((uintptr_t) reserve + alignment - offset);
 108         p = VirtualAlloc(aligned, size, MEM_COMMIT, PAGE_READWRITE);
 109         JS_ASSERT(p == aligned);
 110         return p;
 111     }
 112
 113     /* over allocate to ensure we have an aligned region */
 114     UnmapPagesAtBase(reserve);
 115     reserve = VirtualAlloc(NULL, size + alignment, MEM_RESERVE, PAGE_NOACCESS);
 116     if (!reserve)
 117         return NULL;
 118
 119     offset = (uintptr_t) reserve & mask;
 120     void *aligned = (void *) ((uintptr_t) reserve + alignment - offset);
 121     p = VirtualAlloc(aligned, size, MEM_COMMIT, PAGE_READWRITE);
 122     JS_ASSERT(p == aligned);
 123
 124     return p;
 125 }
 126
 127 static void
 128 UnmapPages(void *p, size_t size)
 129 {
 130     if (VirtualFree(p, 0, MEM_RELEASE))
 131         return;
 132
 133     /* We could have used the over allocation. */
 134     JS_ASSERT(GetLastError() == ERROR_INVALID_PARAMETER);
 135     MEMORY_BASIC_INFORMATION info;
 136     VirtualQuery(p, &info, sizeof(info));
 137
 138     UnmapPagesAtBase(info.AllocationBase);
 139 }
 140
 141 # else /* WINCE */
 142
 143 static void *
 144 MapPages(void *addr, size_t size)
 145 {
 146     void *p = VirtualAlloc(addr, size, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
 147     JS_ASSERT_IF(p && addr, p == addr);
 148     return p;
 149 }
 150
 151 static void
 152 UnmapPages(void *addr, size_t size)
 153 {
 154     JS_ALWAYS_TRUE(VirtualFree(addr, 0, MEM_RELEASE));
 155 }
 156
 157 # endif /* !WINCE */
 158
 159 #elif defined(XP_MACOSX) || defined(DARWIN)
 160
 161 static void *
 162 MapPages(void *addr, size_t size)
 163 {
 164     vm_address_t p;
 165     int flags;
 166     if (addr) {
 167         p = (vm_address_t) addr;
 168         flags = 0;
 169     } else {
 170         flags = VM_FLAGS_ANYWHERE;
 171     }
 172
 173     kern_return_t err = vm_allocate((vm_map_t) mach_task_self(),
 174                                     &p, (vm_size_t) size, flags);
 175     if (err != KERN_SUCCESS)
 176         return NULL;
 177
 178     JS_ASSERT(p);
 179     JS_ASSERT_IF(addr, p == (vm_address_t) addr);
 180     return (void *) p;
 181 }
 182
 183 static void
 184 UnmapPages(void *addr, size_t size)
 185 {
 186     JS_ALWAYS_TRUE(vm_deallocate((vm_map_t) mach_task_self(),
 187                                  (vm_address_t) addr,
 188                                  (vm_size_t) size)
 189                    == KERN_SUCCESS);
 190 }
 191
 192 #elif defined(XP_UNIX) || defined(XP_BEOS)
 193
 194 /* Required on Solaris 10. Might improve performance elsewhere. */
 195 # if defined(SOLARIS) && defined(MAP_ALIGN)
 196 #  define JS_GC_HAS_MAP_ALIGN
 197
 198 static void *
 199 MapAlignedPages(size_t size, size_t alignment)
 200 {
 201     /*
 202      * We don't use MAP_FIXED here, because it can cause the *replacement*
 203      * of existing mappings, and we only want to create new mappings.
 204      */
 205 #ifdef SOLARIS
 206     void *p = mmap((caddr_t) alignment, size, PROT_READ | PROT_WRITE,
 207                      MAP_PRIVATE | MAP_NOSYNC | MAP_ALIGN | MAP_ANON, -1, 0);
 208 #else
 209     void *p = mmap((void *) alignment, size, PROT_READ | PROT_WRITE,
 210                      MAP_PRIVATE | MAP_NOSYNC | MAP_ALIGN | MAP_ANON, -1, 0);
 211 #endif
 212     if (p == MAP_FAILED)
 213         return NULL;
 214     return p;
 215 }
 216
 217 # else /* JS_GC_HAS_MAP_ALIGN */
 218
 219 static void *
 220 MapPages(void *addr, size_t size)
 221 {
 222     /*
 223      * We don't use MAP_FIXED here, because it can cause the *replacement*
 224      * of existing mappings, and we only want to create new mappings.
 225      */
 226     void *p = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON,
 227                    -1, 0);
 228     if (p == MAP_FAILED)
 229         return NULL;
 230     if (addr && p != addr) {
 231         /* We succeeded in mapping memory, but not in the right place. */
 232         JS_ALWAYS_TRUE(munmap(p, size) == 0);
 233         return NULL;
 234     }
 235     return p;
 236 }
 237
 238 # endif /* !JS_GC_HAS_MAP_ALIGN */
 239
 240 static void
 241 UnmapPages(void *addr, size_t size)
 242 {
 243 #ifdef SOLARIS
 244     JS_ALWAYS_TRUE(munmap((caddr_t) addr, size) == 0);
 245 #else
 246     JS_ALWAYS_TRUE(munmap(addr, size) == 0);
 247 #endif
 248 }
 249
 250 #endif
 251
 252 namespace js {
 253
 254 GCChunkAllocator defaultGCChunkAllocator;
 255
 256 inline void *
 257 FindChunkStart(void *p)
 258 {
 259     jsuword addr = reinterpret_cast<jsuword>(p);
 260     addr = (addr + GC_CHUNK_MASK) & ~GC_CHUNK_MASK;
 261     return reinterpret_cast<void *>(addr);
 262 }
 263
 264 JS_FRIEND_API(void *)
 265 AllocGCChunk()
 266 {
 267     void *p;
 268
 269 #ifdef JS_GC_HAS_MAP_ALIGN
 270     p = MapAlignedPages(GC_CHUNK_SIZE, GC_CHUNK_SIZE);
 271     if (!p)
 272         return NULL;
 273 #else
 274     /*
 275      * Windows requires that there be a 1:1 mapping between VM allocation
 276      * and deallocation operations.  Therefore, take care here to acquire the
 277      * final result via one mapping operation.  This means unmapping any
 278      * preliminary result that is not correctly aligned.
 279      */
 280     p = MapPages(NULL, GC_CHUNK_SIZE);
 281     if (!p)
 282         return NULL;
 283
 284     if (reinterpret_cast<jsuword>(p) & GC_CHUNK_MASK) {
 285         UnmapPages(p, GC_CHUNK_SIZE);
 286         p = MapPages(FindChunkStart(p), GC_CHUNK_SIZE);
 287         while (!p) {
 288             /*
 289              * Over-allocate in order to map a memory region that is
 290              * definitely large enough then deallocate and allocate again the
 291              * correct size, within the over-sized mapping.
 292              */
 293             p = MapPages(NULL, GC_CHUNK_SIZE * 2);
 294             if (!p)
 295                 return 0;
 296             UnmapPages(p, GC_CHUNK_SIZE * 2);
 297             p = MapPages(FindChunkStart(p), GC_CHUNK_SIZE);
 298
 299             /*
 300              * Failure here indicates a race with another thread, so
 301              * try again.
 302              */
 303         }
 304     }
 305 #endif /* !JS_GC_HAS_MAP_ALIGN */
 306
 307     JS_ASSERT(!(reinterpret_cast<jsuword>(p) & GC_CHUNK_MASK));
 308     return p;
 309 }
 310
 311 JS_FRIEND_API(void)
 312 FreeGCChunk(void *p)
 313 {
 314     JS_ASSERT(p);
 315     JS_ASSERT(!(reinterpret_cast<jsuword>(p) & GC_CHUNK_MASK));
 316     UnmapPages(p, GC_CHUNK_SIZE);
 317 }
 318
 319 } /* namespace js */
 320