1 /*
   2  * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "logging/log.hpp"
  27 #include "memory/resourceArea.hpp"
  28 #include "memory/virtualspace.hpp"
  29 #include "oops/compressedOops.hpp"
  30 #include "oops/markWord.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/globals_extension.hpp"
  33 #include "runtime/java.hpp"
  34 #include "runtime/os.hpp"
  35 #include "services/memTracker.hpp"
  36 #include "utilities/align.hpp"
  37 #include "utilities/formatBuffer.hpp"
  38 #include "utilities/powerOfTwo.hpp"
  39 
  40 // ReservedSpace
  41 
  42 // Dummy constructor
  43 ReservedSpace::ReservedSpace() : _base(NULL), _size(0), _noaccess_prefix(0),
  44     _alignment(0), _special(false), _fd_for_heap(-1), _executable(false) {
  45 }
  46 
  47 ReservedSpace::ReservedSpace(size_t size) : _fd_for_heap(-1) {
  48   // Want to use large pages where possible. If the size is
  49   // not large page aligned the mapping will be a mix of
  50   // large and normal pages.
  51   size_t page_size = os::page_size_for_region_unaligned(size, 1);
  52   size_t alignment = os::vm_allocation_granularity();
  53   initialize(size, alignment, page_size, NULL, false);
  54 }
  55 
  56 ReservedSpace::ReservedSpace(size_t size, size_t preferred_page_size) : _fd_for_heap(-1) {
  57   // When a page size is given we don't want to mix large
  58   // and normal pages. If the size is not a multiple of the
  59   // page size it will be aligned up to achieve this.
  60   size_t alignment = os::vm_allocation_granularity();;
  61   if (preferred_page_size != (size_t)os::vm_page_size()) {
  62     alignment = MAX2(preferred_page_size, alignment);
  63     size = align_up(size, alignment);
  64   }
  65   initialize(size, alignment, preferred_page_size, NULL, false);
  66 }
  67 
  68 ReservedSpace::ReservedSpace(size_t size,
  69                              size_t alignment,
  70                              size_t page_size,
  71                              char* requested_address) : _fd_for_heap(-1) {
  72   initialize(size, alignment, page_size, requested_address, false);
  73 }
  74 
  75 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment, size_t page_size,
  76                              bool special, bool executable) : _fd_for_heap(-1) {
  77   assert((size % os::vm_allocation_granularity()) == 0,
  78          "size not allocation aligned");
  79   initialize_members(base, size, alignment, page_size, special, executable);
  80 }
  81 
  82 // Helper method
  83 static char* attempt_map_or_reserve_memory_at(char* base, size_t size, int fd, bool executable) {
  84   if (fd != -1) {
  85     return os::attempt_map_memory_to_file_at(base, size, fd);
  86   }
  87   return os::attempt_reserve_memory_at(base, size, executable);
  88 }
  89 
  90 // Helper method
  91 static char* map_or_reserve_memory(size_t size, int fd, bool executable) {
  92   if (fd != -1) {
  93     return os::map_memory_to_file(size, fd);
  94   }
  95   return os::reserve_memory(size, executable);
  96 }
  97 
  98 // Helper method
  99 static char* map_or_reserve_memory_aligned(size_t size, size_t alignment, int fd, bool executable) {
 100   if (fd != -1) {
 101     return os::map_memory_to_file_aligned(size, alignment, fd);
 102   }
 103   return os::reserve_memory_aligned(size, alignment, executable);
 104 }
 105 
 106 // Helper method
 107 static void unmap_or_release_memory(char* base, size_t size, bool is_file_mapped) {
 108   if (is_file_mapped) {
 109     if (!os::unmap_memory(base, size)) {
 110       fatal("os::unmap_memory failed");
 111     }
 112   } else if (!os::release_memory(base, size)) {
 113     fatal("os::release_memory failed");
 114   }
 115 }
 116 
 117 // Helper method
 118 static bool failed_to_reserve_as_requested(char* base, char* requested_address) {
 119   if (base == requested_address || requested_address == NULL) {
 120     return false; // did not fail
 121   }
 122 
 123   if (base != NULL) {
 124     // Different reserve address may be acceptable in other cases
 125     // but for compressed oops heap should be at requested address.
 126     assert(UseCompressedOops, "currently requested address used only for compressed oops");
 127     log_debug(gc, heap, coops)("Reserved memory not at requested address: " PTR_FORMAT " vs " PTR_FORMAT, p2i(base), p2i(requested_address));
 128   }
 129   return true;
 130 }
 131 
 132 static bool use_explicit_large_pages(size_t page_size) {
 133   return !os::can_commit_large_page_memory() &&
 134          page_size != (size_t) os::vm_page_size();
 135 }
 136 
 137 static bool large_pages_requested() {
 138   return UseLargePages &&
 139          (!FLAG_IS_DEFAULT(UseLargePages) || !FLAG_IS_DEFAULT(LargePageSizeInBytes));
 140 }
 141 
 142 static char* reserve_memory(char* requested_address, const size_t size,
 143                             const size_t alignment, int fd, bool exec) {
 144   char* base;
 145   // If the memory was requested at a particular address, use
 146   // os::attempt_reserve_memory_at() to avoid mapping over something
 147   // important.  If the reservation fails, return NULL.
 148   if (requested_address != 0) {
 149     assert(is_aligned(requested_address, alignment),
 150            "Requested address " PTR_FORMAT " must be aligned to " SIZE_FORMAT,
 151            p2i(requested_address), alignment);
 152     base = attempt_map_or_reserve_memory_at(requested_address, size, fd, exec);
 153   } else {
 154     // Optimistically assume that the OS returns an aligned base pointer.
 155     // When reserving a large address range, most OSes seem to align to at
 156     // least 64K.
 157     base = map_or_reserve_memory(size, fd, exec);
 158     // Check alignment constraints. This is only needed when there is
 159     // no requested address.
 160     if (!is_aligned(base, alignment)) {
 161       // Base not aligned, retry.
 162       unmap_or_release_memory(base, size, fd != -1 /*is_file_mapped*/);
 163       // Map using the requested alignment.
 164       base = map_or_reserve_memory_aligned(size, alignment, fd, exec);
 165     }
 166   }
 167 
 168   return base;
 169 }
 170 
 171 static char* reserve_memory_special(char* requested_address, const size_t size,
 172                                     const size_t alignment, const size_t page_size, bool exec) {
 173 
 174   log_trace(pagesize)("Attempt special mapping: size: " SIZE_FORMAT "%s, "
 175                       "alignment: " SIZE_FORMAT "%s",
 176                       byte_size_in_exact_unit(size), exact_unit_for_byte_size(size),
 177                       byte_size_in_exact_unit(alignment), exact_unit_for_byte_size(alignment));
 178 
 179   char* base = os::reserve_memory_special(size, alignment, page_size, requested_address, exec);
 180   if (base != NULL) {
 181     // Check alignment constraints.
 182     assert(is_aligned(base, alignment),
 183            "reserve_memory_special() returned an unaligned address, base: " PTR_FORMAT
 184            " alignment: " SIZE_FORMAT_HEX,
 185            p2i(base), alignment);
 186   } else {
 187     if (large_pages_requested()) {
 188       log_debug(gc, heap, coops)("Reserve regular memory without large pages");
 189     }
 190   }
 191   return base;
 192 }
 193 
 194 void ReservedSpace::clear_members() {
 195   initialize_members(NULL, 0, 0, 0, false, false);
 196 }
 197 
 198 void ReservedSpace::initialize_members(char* base, size_t size, size_t alignment,
 199                                        size_t page_size, bool special, bool executable) {
 200   _base = base;
 201   _size = size;
 202   _alignment = alignment;
 203   _page_size = page_size;
 204   _special = special;
 205   _executable = executable;
 206   _noaccess_prefix = 0;
 207 }
 208 
 209 void ReservedSpace::reserve(size_t size,
 210                             size_t alignment,
 211                             size_t page_size,
 212                             char* requested_address,
 213                             bool executable) {
 214   assert(is_aligned(size, alignment), "Size must be aligned to the requested alignment");
 215 
 216   // There are basically three different cases that we need to handle below:
 217   // - Mapping backed by a file
 218   // - Mapping backed by explicit large pages
 219   // - Mapping backed by normal pages or transparent huge pages
 220   // The first two have restrictions that requires the whole mapping to be
 221   // committed up front. To record this the ReservedSpace is marked 'special'.
 222 
 223   if (_fd_for_heap != -1) {
 224     // When there is a backing file directory for this space then whether
 225     // large pages are allocated is up to the filesystem of the backing file.
 226     // So UseLargePages is not taken into account for this reservation.
 227     char* base = reserve_memory(requested_address, size, alignment, _fd_for_heap, executable);
 228     if (base != NULL) {
 229       initialize_members(base, size, alignment, os::vm_page_size(), true, executable);
 230     }
 231     // Always return, not possible to fall back to reservation not using a file.
 232     return;
 233   } else if (use_explicit_large_pages(page_size)) {
 234     // System can't commit large pages i.e. use transparent huge pages and
 235     // the caller requested large pages. To satisfy this request we use
 236     // explicit large pages and these have to be committed up front to ensure
 237     // no reservations are lost.
 238 
 239     char* base = reserve_memory_special(requested_address, size, alignment, page_size, executable);
 240     if (base != NULL) {
 241       // Successful reservation using large pages.
 242       initialize_members(base, size, alignment, page_size, true, executable);
 243       return;
 244     }
 245     // Failed to reserve explicit large pages, fall back to normal reservation.
 246     page_size = os::vm_page_size();
 247   }
 248 
 249   // Not a 'special' reservation.
 250   char* base = reserve_memory(requested_address, size, alignment, -1, executable);
 251   if (base != NULL) {
 252     // Successful mapping.
 253     initialize_members(base, size, alignment, page_size, false, executable);
 254   }
 255 }
 256 
 257 void ReservedSpace::initialize(size_t size,
 258                                size_t alignment,
 259                                size_t page_size,
 260                                char* requested_address,
 261                                bool executable) {
 262   const size_t granularity = os::vm_allocation_granularity();
 263   assert((size & (granularity - 1)) == 0,
 264          "size not aligned to os::vm_allocation_granularity()");
 265   assert((alignment & (granularity - 1)) == 0,
 266          "alignment not aligned to os::vm_allocation_granularity()");
 267   assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
 268          "not a power of 2");
 269   assert(page_size >= (size_t) os::vm_page_size(), "Invalid page size");
 270   assert(is_power_of_2(page_size), "Invalid page size");
 271 
 272   clear_members();
 273 
 274   if (size == 0) {
 275     return;
 276   }
 277 
 278   // Adjust alignment to not be 0.
 279   alignment = MAX2(alignment, (size_t)os::vm_page_size());
 280 
 281   // Reserve the memory.
 282   reserve(size, alignment, page_size, requested_address, executable);
 283 
 284   // Check that the requested address is used if given.
 285   if (failed_to_reserve_as_requested(_base, requested_address)) {
 286     // OS ignored the requested address, release the reservation.
 287     release();
 288     return;
 289   }
 290 }
 291 
 292 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment) {
 293   assert(partition_size <= size(), "partition failed");
 294   ReservedSpace result(base(), partition_size, alignment, page_size(), special(), executable());
 295   return result;
 296 }
 297 
 298 
 299 ReservedSpace
 300 ReservedSpace::last_part(size_t partition_size, size_t alignment) {
 301   assert(partition_size <= size(), "partition failed");
 302   ReservedSpace result(base() + partition_size, size() - partition_size,
 303                        alignment, page_size(), special(), executable());
 304   return result;
 305 }
 306 
 307 
 308 size_t ReservedSpace::page_align_size_up(size_t size) {
 309   return align_up(size, os::vm_page_size());
 310 }
 311 
 312 
 313 size_t ReservedSpace::page_align_size_down(size_t size) {
 314   return align_down(size, os::vm_page_size());
 315 }
 316 
 317 
 318 size_t ReservedSpace::allocation_align_size_up(size_t size) {
 319   return align_up(size, os::vm_allocation_granularity());
 320 }
 321 
 322 void ReservedSpace::release() {
 323   if (is_reserved()) {
 324     char *real_base = _base - _noaccess_prefix;
 325     const size_t real_size = _size + _noaccess_prefix;
 326     if (special()) {
 327       if (_fd_for_heap != -1) {
 328         os::unmap_memory(real_base, real_size);
 329       } else {
 330         os::release_memory_special(real_base, real_size);
 331       }
 332     } else{
 333       os::release_memory(real_base, real_size);
 334     }
 335     clear_members();
 336   }
 337 }
 338 
 339 static size_t noaccess_prefix_size(size_t alignment) {
 340   return lcm(os::vm_page_size(), alignment);
 341 }
 342 
 343 void ReservedHeapSpace::establish_noaccess_prefix() {
 344   assert(_alignment >= (size_t)os::vm_page_size(), "must be at least page size big");
 345   _noaccess_prefix = noaccess_prefix_size(_alignment);
 346 
 347   if (base() && base() + _size > (char *)OopEncodingHeapMax) {
 348     if (true
 349         WIN64_ONLY(&& !UseLargePages)
 350         AIX_ONLY(&& os::vm_page_size() != 64*K)) {
 351       // Protect memory at the base of the allocated region.
 352       // If special, the page was committed (only matters on windows)
 353       if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE, _special)) {
 354         fatal("cannot protect protection page");
 355       }
 356       log_debug(gc, heap, coops)("Protected page at the reserved heap base: "
 357                                  PTR_FORMAT " / " INTX_FORMAT " bytes",
 358                                  p2i(_base),
 359                                  _noaccess_prefix);
 360       assert(CompressedOops::use_implicit_null_checks() == true, "not initialized?");
 361     } else {
 362       CompressedOops::set_use_implicit_null_checks(false);
 363     }
 364   }
 365 
 366   _base += _noaccess_prefix;
 367   _size -= _noaccess_prefix;
 368   assert(((uintptr_t)_base % _alignment == 0), "must be exactly of required alignment");
 369 }
 370 
 371 // Tries to allocate memory of size 'size' at address requested_address with alignment 'alignment'.
 372 // Does not check whether the reserved memory actually is at requested_address, as the memory returned
 373 // might still fulfill the wishes of the caller.
 374 // Assures the memory is aligned to 'alignment'.
 375 // NOTE: If ReservedHeapSpace already points to some reserved memory this is freed, first.
 376 void ReservedHeapSpace::try_reserve_heap(size_t size,
 377                                          size_t alignment,
 378                                          size_t page_size,
 379                                          char* requested_address) {
 380   if (_base != NULL) {
 381     // We tried before, but we didn't like the address delivered.
 382     release();
 383   }
 384 
 385   // Try to reserve the memory for the heap.
 386   log_trace(gc, heap, coops)("Trying to allocate at address " PTR_FORMAT
 387                              " heap of size " SIZE_FORMAT_HEX,
 388                              p2i(requested_address),
 389                              size);
 390 
 391   reserve(size, alignment, page_size, requested_address, false);
 392 
 393   // Check alignment constraints.
 394   if (is_reserved() && !is_aligned(_base, _alignment)) {
 395     // Base not aligned, retry.
 396     release();
 397   }
 398 }
 399 
 400 void ReservedHeapSpace::try_reserve_range(char *highest_start,
 401                                           char *lowest_start,
 402                                           size_t attach_point_alignment,
 403                                           char *aligned_heap_base_min_address,
 404                                           char *upper_bound,
 405                                           size_t size,
 406                                           size_t alignment,
 407                                           size_t page_size) {
 408   const size_t attach_range = highest_start - lowest_start;
 409   // Cap num_attempts at possible number.
 410   // At least one is possible even for 0 sized attach range.
 411   const uint64_t num_attempts_possible = (attach_range / attach_point_alignment) + 1;
 412   const uint64_t num_attempts_to_try   = MIN2((uint64_t)HeapSearchSteps, num_attempts_possible);
 413 
 414   const size_t stepsize = (attach_range == 0) ? // Only one try.
 415     (size_t) highest_start : align_up(attach_range / num_attempts_to_try, attach_point_alignment);
 416 
 417   // Try attach points from top to bottom.
 418   char* attach_point = highest_start;
 419   while (attach_point >= lowest_start  &&
 420          attach_point <= highest_start &&  // Avoid wrap around.
 421          ((_base == NULL) ||
 422           (_base < aligned_heap_base_min_address || _base + size > upper_bound))) {
 423     try_reserve_heap(size, alignment, page_size, attach_point);
 424     attach_point -= stepsize;
 425   }
 426 }
 427 
 428 #define SIZE_64K  ((uint64_t) UCONST64(      0x10000))
 429 #define SIZE_256M ((uint64_t) UCONST64(   0x10000000))
 430 #define SIZE_32G  ((uint64_t) UCONST64(  0x800000000))
 431 
 432 // Helper for heap allocation. Returns an array with addresses
 433 // (OS-specific) which are suited for disjoint base mode. Array is
 434 // NULL terminated.
 435 static char** get_attach_addresses_for_disjoint_mode() {
 436   static uint64_t addresses[] = {
 437      2 * SIZE_32G,
 438      3 * SIZE_32G,
 439      4 * SIZE_32G,
 440      8 * SIZE_32G,
 441     10 * SIZE_32G,
 442      1 * SIZE_64K * SIZE_32G,
 443      2 * SIZE_64K * SIZE_32G,
 444      3 * SIZE_64K * SIZE_32G,
 445      4 * SIZE_64K * SIZE_32G,
 446     16 * SIZE_64K * SIZE_32G,
 447     32 * SIZE_64K * SIZE_32G,
 448     34 * SIZE_64K * SIZE_32G,
 449     0
 450   };
 451 
 452   // Sort out addresses smaller than HeapBaseMinAddress. This assumes
 453   // the array is sorted.
 454   uint i = 0;
 455   while (addresses[i] != 0 &&
 456          (addresses[i] < OopEncodingHeapMax || addresses[i] < HeapBaseMinAddress)) {
 457     i++;
 458   }
 459   uint start = i;
 460 
 461   // Avoid more steps than requested.
 462   i = 0;
 463   while (addresses[start+i] != 0) {
 464     if (i == HeapSearchSteps) {
 465       addresses[start+i] = 0;
 466       break;
 467     }
 468     i++;
 469   }
 470 
 471   return (char**) &addresses[start];
 472 }
 473 
 474 void ReservedHeapSpace::initialize_compressed_heap(const size_t size, size_t alignment, size_t page_size) {
 475   guarantee(size + noaccess_prefix_size(alignment) <= OopEncodingHeapMax,
 476             "can not allocate compressed oop heap for this size");
 477   guarantee(alignment == MAX2(alignment, (size_t)os::vm_page_size()), "alignment too small");
 478 
 479   const size_t granularity = os::vm_allocation_granularity();
 480   assert((size & (granularity - 1)) == 0,
 481          "size not aligned to os::vm_allocation_granularity()");
 482   assert((alignment & (granularity - 1)) == 0,
 483          "alignment not aligned to os::vm_allocation_granularity()");
 484   assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
 485          "not a power of 2");
 486 
 487   // The necessary attach point alignment for generated wish addresses.
 488   // This is needed to increase the chance of attaching for mmap and shmat.
 489   const size_t os_attach_point_alignment =
 490     AIX_ONLY(SIZE_256M)  // Known shm boundary alignment.
 491     NOT_AIX(os::vm_allocation_granularity());
 492   const size_t attach_point_alignment = lcm(alignment, os_attach_point_alignment);
 493 
 494   char *aligned_heap_base_min_address = (char *)align_up((void *)HeapBaseMinAddress, alignment);
 495   size_t noaccess_prefix = ((aligned_heap_base_min_address + size) > (char*)OopEncodingHeapMax) ?
 496     noaccess_prefix_size(alignment) : 0;
 497 
 498   // Attempt to alloc at user-given address.
 499   if (!FLAG_IS_DEFAULT(HeapBaseMinAddress)) {
 500     try_reserve_heap(size + noaccess_prefix, alignment, page_size, aligned_heap_base_min_address);
 501     if (_base != aligned_heap_base_min_address) { // Enforce this exact address.
 502       release();
 503     }
 504   }
 505 
 506   // Keep heap at HeapBaseMinAddress.
 507   if (_base == NULL) {
 508 
 509     // Try to allocate the heap at addresses that allow efficient oop compression.
 510     // Different schemes are tried, in order of decreasing optimization potential.
 511     //
 512     // For this, try_reserve_heap() is called with the desired heap base addresses.
 513     // A call into the os layer to allocate at a given address can return memory
 514     // at a different address than requested.  Still, this might be memory at a useful
 515     // address. try_reserve_heap() always returns this allocated memory, as only here
 516     // the criteria for a good heap are checked.
 517 
 518     // Attempt to allocate so that we can run without base and scale (32-Bit unscaled compressed oops).
 519     // Give it several tries from top of range to bottom.
 520     if (aligned_heap_base_min_address + size <= (char *)UnscaledOopHeapMax) {
 521 
 522       // Calc address range within we try to attach (range of possible start addresses).
 523       char* const highest_start = align_down((char *)UnscaledOopHeapMax - size, attach_point_alignment);
 524       char* const lowest_start  = align_up(aligned_heap_base_min_address, attach_point_alignment);
 525       try_reserve_range(highest_start, lowest_start, attach_point_alignment,
 526                         aligned_heap_base_min_address, (char *)UnscaledOopHeapMax, size, alignment, page_size);
 527     }
 528 
 529     // zerobased: Attempt to allocate in the lower 32G.
 530     // But leave room for the compressed class pointers, which is allocated above
 531     // the heap.
 532     char *zerobased_max = (char *)OopEncodingHeapMax;
 533     const size_t class_space = align_up(CompressedClassSpaceSize, alignment);
 534     // For small heaps, save some space for compressed class pointer
 535     // space so it can be decoded with no base.
 536     if (UseCompressedClassPointers && !UseSharedSpaces &&
 537         OopEncodingHeapMax <= KlassEncodingMetaspaceMax &&
 538         (uint64_t)(aligned_heap_base_min_address + size + class_space) <= KlassEncodingMetaspaceMax) {
 539       zerobased_max = (char *)OopEncodingHeapMax - class_space;
 540     }
 541 
 542     // Give it several tries from top of range to bottom.
 543     if (aligned_heap_base_min_address + size <= zerobased_max &&    // Zerobased theoretical possible.
 544         ((_base == NULL) ||                        // No previous try succeeded.
 545          (_base + size > zerobased_max))) {        // Unscaled delivered an arbitrary address.
 546 
 547       // Calc address range within we try to attach (range of possible start addresses).
 548       char *const highest_start = align_down(zerobased_max - size, attach_point_alignment);
 549       // Need to be careful about size being guaranteed to be less
 550       // than UnscaledOopHeapMax due to type constraints.
 551       char *lowest_start = aligned_heap_base_min_address;
 552       uint64_t unscaled_end = UnscaledOopHeapMax - size;
 553       if (unscaled_end < UnscaledOopHeapMax) { // unscaled_end wrapped if size is large
 554         lowest_start = MAX2(lowest_start, (char*)unscaled_end);
 555       }
 556       lowest_start = align_up(lowest_start, attach_point_alignment);
 557       try_reserve_range(highest_start, lowest_start, attach_point_alignment,
 558                         aligned_heap_base_min_address, zerobased_max, size, alignment, page_size);
 559     }
 560 
 561     // Now we go for heaps with base != 0.  We need a noaccess prefix to efficiently
 562     // implement null checks.
 563     noaccess_prefix = noaccess_prefix_size(alignment);
 564 
 565     // Try to attach at addresses that are aligned to OopEncodingHeapMax. Disjointbase mode.
 566     char** addresses = get_attach_addresses_for_disjoint_mode();
 567     int i = 0;
 568     while (addresses[i] &&                                 // End of array not yet reached.
 569            ((_base == NULL) ||                             // No previous try succeeded.
 570             (_base + size >  (char *)OopEncodingHeapMax && // Not zerobased or unscaled address.
 571              !CompressedOops::is_disjoint_heap_base_address((address)_base)))) {  // Not disjoint address.
 572       char* const attach_point = addresses[i];
 573       assert(attach_point >= aligned_heap_base_min_address, "Flag support broken");
 574       try_reserve_heap(size + noaccess_prefix, alignment, page_size, attach_point);
 575       i++;
 576     }
 577 
 578     // Last, desperate try without any placement.
 579     if (_base == NULL) {
 580       log_trace(gc, heap, coops)("Trying to allocate at address NULL heap of size " SIZE_FORMAT_HEX, size + noaccess_prefix);
 581       initialize(size + noaccess_prefix, alignment, page_size, NULL, false);
 582     }
 583   }
 584 }
 585 
 586 ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, size_t page_size, const char* heap_allocation_directory) : ReservedSpace() {
 587 
 588   if (size == 0) {
 589     return;
 590   }
 591 
 592   if (heap_allocation_directory != NULL) {
 593     _fd_for_heap = os::create_file_for_heap(heap_allocation_directory);
 594     if (_fd_for_heap == -1) {
 595       vm_exit_during_initialization(
 596         err_msg("Could not create file for Heap at location %s", heap_allocation_directory));
 597     }
 598     // When there is a backing file directory for this space then whether
 599     // large pages are allocated is up to the filesystem of the backing file.
 600     // If requested, let the user know that explicit large pages can't be used.
 601     if (use_explicit_large_pages(page_size) && large_pages_requested()) {
 602       log_debug(gc, heap)("Cannot allocate explicit large pages for Java Heap when AllocateHeapAt option is set.");
 603     }
 604   }
 605 
 606   // Heap size should be aligned to alignment, too.
 607   guarantee(is_aligned(size, alignment), "set by caller");
 608 
 609   if (UseCompressedOops) {
 610     initialize_compressed_heap(size, alignment, page_size);
 611     if (_size > size) {
 612       // We allocated heap with noaccess prefix.
 613       // It can happen we get a zerobased/unscaled heap with noaccess prefix,
 614       // if we had to try at arbitrary address.
 615       establish_noaccess_prefix();
 616     }
 617   } else {
 618     initialize(size, alignment, page_size, NULL, false);
 619   }
 620 
 621   assert(markWord::encode_pointer_as_mark(_base).decode_pointer() == _base,
 622          "area must be distinguishable from marks for mark-sweep");
 623   assert(markWord::encode_pointer_as_mark(&_base[size]).decode_pointer() == &_base[size],
 624          "area must be distinguishable from marks for mark-sweep");
 625 
 626   if (base() != NULL) {
 627     MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
 628   }
 629 
 630   if (_fd_for_heap != -1) {
 631     os::close(_fd_for_heap);
 632   }
 633 }
 634 
 635 MemRegion ReservedHeapSpace::region() const {
 636   return MemRegion((HeapWord*)base(), (HeapWord*)end());
 637 }
 638 
 639 // Reserve space for code segment.  Same as Java heap only we mark this as
 640 // executable.
 641 ReservedCodeSpace::ReservedCodeSpace(size_t r_size,
 642                                      size_t rs_align,
 643                                      size_t rs_page_size) : ReservedSpace() {
 644   initialize(r_size, rs_align, rs_page_size, /*requested address*/ NULL, /*executable*/ true);
 645   MemTracker::record_virtual_memory_type((address)base(), mtCode);
 646 }
 647 
 648 // VirtualSpace
 649 
 650 VirtualSpace::VirtualSpace() {
 651   _low_boundary           = NULL;
 652   _high_boundary          = NULL;
 653   _low                    = NULL;
 654   _high                   = NULL;
 655   _lower_high             = NULL;
 656   _middle_high            = NULL;
 657   _upper_high             = NULL;
 658   _lower_high_boundary    = NULL;
 659   _middle_high_boundary   = NULL;
 660   _upper_high_boundary    = NULL;
 661   _lower_alignment        = 0;
 662   _middle_alignment       = 0;
 663   _upper_alignment        = 0;
 664   _special                = false;
 665   _executable             = false;
 666 }
 667 
 668 
 669 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
 670   const size_t max_commit_granularity = os::page_size_for_region_unaligned(rs.size(), 1);
 671   return initialize_with_granularity(rs, committed_size, max_commit_granularity);
 672 }
 673 
 674 bool VirtualSpace::initialize_with_granularity(ReservedSpace rs, size_t committed_size, size_t max_commit_granularity) {
 675   if(!rs.is_reserved()) return false;  // allocation failed.
 676   assert(_low_boundary == NULL, "VirtualSpace already initialized");
 677   assert(max_commit_granularity > 0, "Granularity must be non-zero.");
 678 
 679   _low_boundary  = rs.base();
 680   _high_boundary = low_boundary() + rs.size();
 681 
 682   _low = low_boundary();
 683   _high = low();
 684 
 685   _special = rs.special();
 686   _executable = rs.executable();
 687 
 688   // When a VirtualSpace begins life at a large size, make all future expansion
 689   // and shrinking occur aligned to a granularity of large pages.  This avoids
 690   // fragmentation of physical addresses that inhibits the use of large pages
 691   // by the OS virtual memory system.  Empirically,  we see that with a 4MB
 692   // page size, the only spaces that get handled this way are codecache and
 693   // the heap itself, both of which provide a substantial performance
 694   // boost in many benchmarks when covered by large pages.
 695   //
 696   // No attempt is made to force large page alignment at the very top and
 697   // bottom of the space if they are not aligned so already.
 698   _lower_alignment  = os::vm_page_size();
 699   _middle_alignment = max_commit_granularity;
 700   _upper_alignment  = os::vm_page_size();
 701 
 702   // End of each region
 703   _lower_high_boundary = align_up(low_boundary(), middle_alignment());
 704   _middle_high_boundary = align_down(high_boundary(), middle_alignment());
 705   _upper_high_boundary = high_boundary();
 706 
 707   // High address of each region
 708   _lower_high = low_boundary();
 709   _middle_high = lower_high_boundary();
 710   _upper_high = middle_high_boundary();
 711 
 712   // commit to initial size
 713   if (committed_size > 0) {
 714     if (!expand_by(committed_size)) {
 715       return false;
 716     }
 717   }
 718   return true;
 719 }
 720 
 721 
 722 VirtualSpace::~VirtualSpace() {
 723   release();
 724 }
 725 
 726 
 727 void VirtualSpace::release() {
 728   // This does not release memory it reserved.
 729   // Caller must release via rs.release();
 730   _low_boundary           = NULL;
 731   _high_boundary          = NULL;
 732   _low                    = NULL;
 733   _high                   = NULL;
 734   _lower_high             = NULL;
 735   _middle_high            = NULL;
 736   _upper_high             = NULL;
 737   _lower_high_boundary    = NULL;
 738   _middle_high_boundary   = NULL;
 739   _upper_high_boundary    = NULL;
 740   _lower_alignment        = 0;
 741   _middle_alignment       = 0;
 742   _upper_alignment        = 0;
 743   _special                = false;
 744   _executable             = false;
 745 }
 746 
 747 
 748 size_t VirtualSpace::committed_size() const {
 749   return pointer_delta(high(), low(), sizeof(char));
 750 }
 751 
 752 
 753 size_t VirtualSpace::reserved_size() const {
 754   return pointer_delta(high_boundary(), low_boundary(), sizeof(char));
 755 }
 756 
 757 
 758 size_t VirtualSpace::uncommitted_size()  const {
 759   return reserved_size() - committed_size();
 760 }
 761 
 762 size_t VirtualSpace::actual_committed_size() const {
 763   // Special VirtualSpaces commit all reserved space up front.
 764   if (special()) {
 765     return reserved_size();
 766   }
 767 
 768   size_t committed_low    = pointer_delta(_lower_high,  _low_boundary,         sizeof(char));
 769   size_t committed_middle = pointer_delta(_middle_high, _lower_high_boundary,  sizeof(char));
 770   size_t committed_high   = pointer_delta(_upper_high,  _middle_high_boundary, sizeof(char));
 771 
 772 #ifdef ASSERT
 773   size_t lower  = pointer_delta(_lower_high_boundary,  _low_boundary,         sizeof(char));
 774   size_t middle = pointer_delta(_middle_high_boundary, _lower_high_boundary,  sizeof(char));
 775   size_t upper  = pointer_delta(_upper_high_boundary,  _middle_high_boundary, sizeof(char));
 776 
 777   if (committed_high > 0) {
 778     assert(committed_low == lower, "Must be");
 779     assert(committed_middle == middle, "Must be");
 780   }
 781 
 782   if (committed_middle > 0) {
 783     assert(committed_low == lower, "Must be");
 784   }
 785   if (committed_middle < middle) {
 786     assert(committed_high == 0, "Must be");
 787   }
 788 
 789   if (committed_low < lower) {
 790     assert(committed_high == 0, "Must be");
 791     assert(committed_middle == 0, "Must be");
 792   }
 793 #endif
 794 
 795   return committed_low + committed_middle + committed_high;
 796 }
 797 
 798 
 799 bool VirtualSpace::contains(const void* p) const {
 800   return low() <= (const char*) p && (const char*) p < high();
 801 }
 802 
 803 static void pretouch_expanded_memory(void* start, void* end) {
 804   assert(is_aligned(start, os::vm_page_size()), "Unexpected alignment");
 805   assert(is_aligned(end,   os::vm_page_size()), "Unexpected alignment");
 806 
 807   os::pretouch_memory(start, end);
 808 }
 809 
 810 static bool commit_expanded(char* start, size_t size, size_t alignment, bool pre_touch, bool executable) {
 811   if (os::commit_memory(start, size, alignment, executable)) {
 812     if (pre_touch || AlwaysPreTouch) {
 813       pretouch_expanded_memory(start, start + size);
 814     }
 815     return true;
 816   }
 817 
 818   debug_only(warning(
 819       "INFO: os::commit_memory(" PTR_FORMAT ", " PTR_FORMAT
 820       " size=" SIZE_FORMAT ", executable=%d) failed",
 821       p2i(start), p2i(start + size), size, executable);)
 822 
 823   return false;
 824 }
 825 
 826 /*
 827    First we need to determine if a particular virtual space is using large
 828    pages.  This is done at the initialize function and only virtual spaces
 829    that are larger than LargePageSizeInBytes use large pages.  Once we
 830    have determined this, all expand_by and shrink_by calls must grow and
 831    shrink by large page size chunks.  If a particular request
 832    is within the current large page, the call to commit and uncommit memory
 833    can be ignored.  In the case that the low and high boundaries of this
 834    space is not large page aligned, the pages leading to the first large
 835    page address and the pages after the last large page address must be
 836    allocated with default pages.
 837 */
 838 bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) {
 839   if (uncommitted_size() < bytes) {
 840     return false;
 841   }
 842 
 843   if (special()) {
 844     // don't commit memory if the entire space is pinned in memory
 845     _high += bytes;
 846     return true;
 847   }
 848 
 849   char* previous_high = high();
 850   char* unaligned_new_high = high() + bytes;
 851   assert(unaligned_new_high <= high_boundary(), "cannot expand by more than upper boundary");
 852 
 853   // Calculate where the new high for each of the regions should be.  If
 854   // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned
 855   // then the unaligned lower and upper new highs would be the
 856   // lower_high() and upper_high() respectively.
 857   char* unaligned_lower_new_high =  MIN2(unaligned_new_high, lower_high_boundary());
 858   char* unaligned_middle_new_high = MIN2(unaligned_new_high, middle_high_boundary());
 859   char* unaligned_upper_new_high =  MIN2(unaligned_new_high, upper_high_boundary());
 860 
 861   // Align the new highs based on the regions alignment.  lower and upper
 862   // alignment will always be default page size.  middle alignment will be
 863   // LargePageSizeInBytes if the actual size of the virtual space is in
 864   // fact larger than LargePageSizeInBytes.
 865   char* aligned_lower_new_high =  align_up(unaligned_lower_new_high, lower_alignment());
 866   char* aligned_middle_new_high = align_up(unaligned_middle_new_high, middle_alignment());
 867   char* aligned_upper_new_high =  align_up(unaligned_upper_new_high, upper_alignment());
 868 
 869   // Determine which regions need to grow in this expand_by call.
 870   // If you are growing in the lower region, high() must be in that
 871   // region so calculate the size based on high().  For the middle and
 872   // upper regions, determine the starting point of growth based on the
 873   // location of high().  By getting the MAX of the region's low address
 874   // (or the previous region's high address) and high(), we can tell if it
 875   // is an intra or inter region growth.
 876   size_t lower_needs = 0;
 877   if (aligned_lower_new_high > lower_high()) {
 878     lower_needs = pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char));
 879   }
 880   size_t middle_needs = 0;
 881   if (aligned_middle_new_high > middle_high()) {
 882     middle_needs = pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char));
 883   }
 884   size_t upper_needs = 0;
 885   if (aligned_upper_new_high > upper_high()) {
 886     upper_needs = pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char));
 887   }
 888 
 889   // Check contiguity.
 890   assert(low_boundary() <= lower_high() && lower_high() <= lower_high_boundary(),
 891          "high address must be contained within the region");
 892   assert(lower_high_boundary() <= middle_high() && middle_high() <= middle_high_boundary(),
 893          "high address must be contained within the region");
 894   assert(middle_high_boundary() <= upper_high() && upper_high() <= upper_high_boundary(),
 895          "high address must be contained within the region");
 896 
 897   // Commit regions
 898   if (lower_needs > 0) {
 899     assert(lower_high() + lower_needs <= lower_high_boundary(), "must not expand beyond region");
 900     if (!commit_expanded(lower_high(), lower_needs, _lower_alignment, pre_touch, _executable)) {
 901       return false;
 902     }
 903     _lower_high += lower_needs;
 904   }
 905 
 906   if (middle_needs > 0) {
 907     assert(middle_high() + middle_needs <= middle_high_boundary(), "must not expand beyond region");
 908     if (!commit_expanded(middle_high(), middle_needs, _middle_alignment, pre_touch, _executable)) {
 909       return false;
 910     }
 911     _middle_high += middle_needs;
 912   }
 913 
 914   if (upper_needs > 0) {
 915     assert(upper_high() + upper_needs <= upper_high_boundary(), "must not expand beyond region");
 916     if (!commit_expanded(upper_high(), upper_needs, _upper_alignment, pre_touch, _executable)) {
 917       return false;
 918     }
 919     _upper_high += upper_needs;
 920   }
 921 
 922   _high += bytes;
 923   return true;
 924 }
 925 
 926 // A page is uncommitted if the contents of the entire page is deemed unusable.
 927 // Continue to decrement the high() pointer until it reaches a page boundary
 928 // in which case that particular page can now be uncommitted.
 929 void VirtualSpace::shrink_by(size_t size) {
 930   if (committed_size() < size)
 931     fatal("Cannot shrink virtual space to negative size");
 932 
 933   if (special()) {
 934     // don't uncommit if the entire space is pinned in memory
 935     _high -= size;
 936     return;
 937   }
 938 
 939   char* unaligned_new_high = high() - size;
 940   assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary");
 941 
 942   // Calculate new unaligned address
 943   char* unaligned_upper_new_high =
 944     MAX2(unaligned_new_high, middle_high_boundary());
 945   char* unaligned_middle_new_high =
 946     MAX2(unaligned_new_high, lower_high_boundary());
 947   char* unaligned_lower_new_high =
 948     MAX2(unaligned_new_high, low_boundary());
 949 
 950   // Align address to region's alignment
 951   char* aligned_upper_new_high =  align_up(unaligned_upper_new_high, upper_alignment());
 952   char* aligned_middle_new_high = align_up(unaligned_middle_new_high, middle_alignment());
 953   char* aligned_lower_new_high =  align_up(unaligned_lower_new_high, lower_alignment());
 954 
 955   // Determine which regions need to shrink
 956   size_t upper_needs = 0;
 957   if (aligned_upper_new_high < upper_high()) {
 958     upper_needs =
 959       pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char));
 960   }
 961   size_t middle_needs = 0;
 962   if (aligned_middle_new_high < middle_high()) {
 963     middle_needs =
 964       pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char));
 965   }
 966   size_t lower_needs = 0;
 967   if (aligned_lower_new_high < lower_high()) {
 968     lower_needs =
 969       pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char));
 970   }
 971 
 972   // Check contiguity.
 973   assert(middle_high_boundary() <= upper_high() &&
 974          upper_high() <= upper_high_boundary(),
 975          "high address must be contained within the region");
 976   assert(lower_high_boundary() <= middle_high() &&
 977          middle_high() <= middle_high_boundary(),
 978          "high address must be contained within the region");
 979   assert(low_boundary() <= lower_high() &&
 980          lower_high() <= lower_high_boundary(),
 981          "high address must be contained within the region");
 982 
 983   // Uncommit
 984   if (upper_needs > 0) {
 985     assert(middle_high_boundary() <= aligned_upper_new_high &&
 986            aligned_upper_new_high + upper_needs <= upper_high_boundary(),
 987            "must not shrink beyond region");
 988     if (!os::uncommit_memory(aligned_upper_new_high, upper_needs, _executable)) {
 989       debug_only(warning("os::uncommit_memory failed"));
 990       return;
 991     } else {
 992       _upper_high -= upper_needs;
 993     }
 994   }
 995   if (middle_needs > 0) {
 996     assert(lower_high_boundary() <= aligned_middle_new_high &&
 997            aligned_middle_new_high + middle_needs <= middle_high_boundary(),
 998            "must not shrink beyond region");
 999     if (!os::uncommit_memory(aligned_middle_new_high, middle_needs, _executable)) {
1000       debug_only(warning("os::uncommit_memory failed"));
1001       return;
1002     } else {
1003       _middle_high -= middle_needs;
1004     }
1005   }
1006   if (lower_needs > 0) {
1007     assert(low_boundary() <= aligned_lower_new_high &&
1008            aligned_lower_new_high + lower_needs <= lower_high_boundary(),
1009            "must not shrink beyond region");
1010     if (!os::uncommit_memory(aligned_lower_new_high, lower_needs, _executable)) {
1011       debug_only(warning("os::uncommit_memory failed"));
1012       return;
1013     } else {
1014       _lower_high -= lower_needs;
1015     }
1016   }
1017 
1018   _high -= size;
1019 }
1020 
1021 #ifndef PRODUCT
1022 void VirtualSpace::check_for_contiguity() {
1023   // Check contiguity.
1024   assert(low_boundary() <= lower_high() &&
1025          lower_high() <= lower_high_boundary(),
1026          "high address must be contained within the region");
1027   assert(lower_high_boundary() <= middle_high() &&
1028          middle_high() <= middle_high_boundary(),
1029          "high address must be contained within the region");
1030   assert(middle_high_boundary() <= upper_high() &&
1031          upper_high() <= upper_high_boundary(),
1032          "high address must be contained within the region");
1033   assert(low() >= low_boundary(), "low");
1034   assert(low_boundary() <= lower_high_boundary(), "lower high boundary");
1035   assert(upper_high_boundary() <= high_boundary(), "upper high boundary");
1036   assert(high() <= upper_high(), "upper high");
1037 }
1038 
1039 void VirtualSpace::print_on(outputStream* out) const {
1040   out->print   ("Virtual space:");
1041   if (special()) out->print(" (pinned in memory)");
1042   out->cr();
1043   out->print_cr(" - committed: " SIZE_FORMAT, committed_size());
1044   out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());
1045   out->print_cr(" - [low, high]:     [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(low()), p2i(high()));
1046   out->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(low_boundary()), p2i(high_boundary()));
1047 }
1048 
1049 void VirtualSpace::print() const {
1050   print_on(tty);
1051 }
1052 
1053 #endif