1 /*
   2  * Copyright (c) 1997, 2017, 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 "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/icBuffer.hpp"
  34 #include "code/vtableStubs.hpp"
  35 #include "gc/shared/vmGCOperations.hpp"
  36 #include "interpreter/interpreter.hpp"
  37 #include "logging/log.hpp"
  38 #include "logging/logStream.hpp"
  39 #include "memory/allocation.inline.hpp"
  40 #ifdef ASSERT
  41 #include "memory/guardedMemory.hpp"
  42 #endif
  43 #include "memory/resourceArea.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "prims/jvm_misc.hpp"
  46 #include "prims/privilegedStack.hpp"
  47 #include "runtime/arguments.hpp"
  48 #include "runtime/atomic.hpp"
  49 #include "runtime/frame.inline.hpp"
  50 #include "runtime/interfaceSupport.hpp"
  51 #include "runtime/java.hpp"
  52 #include "runtime/javaCalls.hpp"
  53 #include "runtime/mutexLocker.hpp"
  54 #include "runtime/os.inline.hpp"
  55 #include "runtime/stubRoutines.hpp"
  56 #include "runtime/thread.inline.hpp"
  57 #include "runtime/vm_version.hpp"
  58 #include "services/attachListener.hpp"
  59 #include "services/mallocTracker.hpp"
  60 #include "services/memTracker.hpp"
  61 #include "services/nmtCommon.hpp"
  62 #include "services/threadService.hpp"
  63 #include "utilities/align.hpp"
  64 #include "utilities/defaultStream.hpp"
  65 #include "utilities/events.hpp"
  66 
  67 # include <signal.h>
  68 # include <errno.h>
  69 
  70 OSThread*         os::_starting_thread    = NULL;
  71 address           os::_polling_page       = NULL;
  72 volatile int32_t* os::_mem_serialize_page = NULL;
  73 uintptr_t         os::_serialize_page_mask = 0;
  74 volatile unsigned int os::_rand_seed      = 1;
  75 int               os::_processor_count    = 0;
  76 int               os::_initial_active_processor_count = 0;
  77 size_t            os::_page_sizes[os::page_sizes_max];
  78 
  79 #ifndef PRODUCT
  80 julong os::num_mallocs = 0;         // # of calls to malloc/realloc
  81 julong os::alloc_bytes = 0;         // # of bytes allocated
  82 julong os::num_frees = 0;           // # of calls to free
  83 julong os::free_bytes = 0;          // # of bytes freed
  84 #endif
  85 
  86 static juint cur_malloc_words = 0;  // current size for MallocMaxTestWords
  87 
  88 void os_init_globals() {
  89   // Called from init_globals().
  90   // See Threads::create_vm() in thread.cpp, and init.cpp.
  91   os::init_globals();
  92 }
  93 
  94 // Fill in buffer with current local time as an ISO-8601 string.
  95 // E.g., yyyy-mm-ddThh:mm:ss-zzzz.
  96 // Returns buffer, or NULL if it failed.
  97 // This would mostly be a call to
  98 //     strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
  99 // except that on Windows the %z behaves badly, so we do it ourselves.
 100 // Also, people wanted milliseconds on there,
 101 // and strftime doesn't do milliseconds.
 102 char* os::iso8601_time(char* buffer, size_t buffer_length, bool utc) {
 103   // Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
 104   //                                      1         2
 105   //                             12345678901234567890123456789
 106   // format string: "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d"
 107   static const size_t needed_buffer = 29;
 108 
 109   // Sanity check the arguments
 110   if (buffer == NULL) {
 111     assert(false, "NULL buffer");
 112     return NULL;
 113   }
 114   if (buffer_length < needed_buffer) {
 115     assert(false, "buffer_length too small");
 116     return NULL;
 117   }
 118   // Get the current time
 119   jlong milliseconds_since_19700101 = javaTimeMillis();
 120   const int milliseconds_per_microsecond = 1000;
 121   const time_t seconds_since_19700101 =
 122     milliseconds_since_19700101 / milliseconds_per_microsecond;
 123   const int milliseconds_after_second =
 124     milliseconds_since_19700101 % milliseconds_per_microsecond;
 125   // Convert the time value to a tm and timezone variable
 126   struct tm time_struct;
 127   if (utc) {
 128     if (gmtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
 129       assert(false, "Failed gmtime_pd");
 130       return NULL;
 131     }
 132   } else {
 133     if (localtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
 134       assert(false, "Failed localtime_pd");
 135       return NULL;
 136     }
 137   }
 138 #if defined(_ALLBSD_SOURCE)
 139   const time_t zone = (time_t) time_struct.tm_gmtoff;
 140 #else
 141   const time_t zone = timezone;
 142 #endif
 143 
 144   // If daylight savings time is in effect,
 145   // we are 1 hour East of our time zone
 146   const time_t seconds_per_minute = 60;
 147   const time_t minutes_per_hour = 60;
 148   const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
 149   time_t UTC_to_local = zone;
 150   if (time_struct.tm_isdst > 0) {
 151     UTC_to_local = UTC_to_local - seconds_per_hour;
 152   }
 153 
 154   // No offset when dealing with UTC
 155   if (utc) {
 156     UTC_to_local = 0;
 157   }
 158 
 159   // Compute the time zone offset.
 160   //    localtime_pd() sets timezone to the difference (in seconds)
 161   //    between UTC and and local time.
 162   //    ISO 8601 says we need the difference between local time and UTC,
 163   //    we change the sign of the localtime_pd() result.
 164   const time_t local_to_UTC = -(UTC_to_local);
 165   // Then we have to figure out if if we are ahead (+) or behind (-) UTC.
 166   char sign_local_to_UTC = '+';
 167   time_t abs_local_to_UTC = local_to_UTC;
 168   if (local_to_UTC < 0) {
 169     sign_local_to_UTC = '-';
 170     abs_local_to_UTC = -(abs_local_to_UTC);
 171   }
 172   // Convert time zone offset seconds to hours and minutes.
 173   const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
 174   const time_t zone_min =
 175     ((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);
 176 
 177   // Print an ISO 8601 date and time stamp into the buffer
 178   const int year = 1900 + time_struct.tm_year;
 179   const int month = 1 + time_struct.tm_mon;
 180   const int printed = jio_snprintf(buffer, buffer_length,
 181                                    "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d",
 182                                    year,
 183                                    month,
 184                                    time_struct.tm_mday,
 185                                    time_struct.tm_hour,
 186                                    time_struct.tm_min,
 187                                    time_struct.tm_sec,
 188                                    milliseconds_after_second,
 189                                    sign_local_to_UTC,
 190                                    zone_hours,
 191                                    zone_min);
 192   if (printed == 0) {
 193     assert(false, "Failed jio_printf");
 194     return NULL;
 195   }
 196   return buffer;
 197 }
 198 
 199 OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
 200 #ifdef ASSERT
 201   if (!(!thread->is_Java_thread() ||
 202          Thread::current() == thread  ||
 203          Threads_lock->owned_by_self()
 204          || thread->is_Compiler_thread()
 205         )) {
 206     assert(false, "possibility of dangling Thread pointer");
 207   }
 208 #endif
 209 
 210   if (p >= MinPriority && p <= MaxPriority) {
 211     int priority = java_to_os_priority[p];
 212     return set_native_priority(thread, priority);
 213   } else {
 214     assert(false, "Should not happen");
 215     return OS_ERR;
 216   }
 217 }
 218 
 219 // The mapping from OS priority back to Java priority may be inexact because
 220 // Java priorities can map M:1 with native priorities. If you want the definite
 221 // Java priority then use JavaThread::java_priority()
 222 OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
 223   int p;
 224   int os_prio;
 225   OSReturn ret = get_native_priority(thread, &os_prio);
 226   if (ret != OS_OK) return ret;
 227 
 228   if (java_to_os_priority[MaxPriority] > java_to_os_priority[MinPriority]) {
 229     for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
 230   } else {
 231     // niceness values are in reverse order
 232     for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] < os_prio; p--) ;
 233   }
 234   priority = (ThreadPriority)p;
 235   return OS_OK;
 236 }
 237 
 238 bool os::dll_build_name(char* buffer, size_t size, const char* fname) {
 239   int n = jio_snprintf(buffer, size, "%s%s%s", JNI_LIB_PREFIX, fname, JNI_LIB_SUFFIX);
 240   return (n != -1);
 241 }
 242 
 243 // Helper for dll_locate_lib.
 244 // Pass buffer and printbuffer as we already printed the path to buffer
 245 // when we called get_current_directory. This way we avoid another buffer
 246 // of size MAX_PATH.
 247 static bool conc_path_file_and_check(char *buffer, char *printbuffer, size_t printbuflen,
 248                                      const char* pname, char lastchar, const char* fname) {
 249 
 250   // Concatenate path and file name, but don't print double path separators.
 251   const char *filesep = (WINDOWS_ONLY(lastchar == ':' ||) lastchar == os::file_separator()[0]) ?
 252                         "" : os::file_separator();
 253   int ret = jio_snprintf(printbuffer, printbuflen, "%s%s%s", pname, filesep, fname);
 254   // Check whether file exists.
 255   if (ret != -1) {
 256     struct stat statbuf;
 257     return os::stat(buffer, &statbuf) == 0;
 258   }
 259   return false;
 260 }
 261 
 262 bool os::dll_locate_lib(char *buffer, size_t buflen,
 263                         const char* pname, const char* fname) {
 264   bool retval = false;
 265 
 266   size_t fullfnamelen = strlen(JNI_LIB_PREFIX) + strlen(fname) + strlen(JNI_LIB_SUFFIX);
 267   char* fullfname = (char*)NEW_C_HEAP_ARRAY(char, fullfnamelen + 1, mtInternal);
 268   if (dll_build_name(fullfname, fullfnamelen + 1, fname)) {
 269     const size_t pnamelen = pname ? strlen(pname) : 0;
 270 
 271     if (pnamelen == 0) {
 272       // If no path given, use current working directory.
 273       const char* p = get_current_directory(buffer, buflen);
 274       if (p != NULL) {
 275         const size_t plen = strlen(buffer);
 276         const char lastchar = buffer[plen - 1];
 277         retval = conc_path_file_and_check(buffer, &buffer[plen], buflen - plen,
 278                                           "", lastchar, fullfname);
 279       }
 280     } else if (strchr(pname, *os::path_separator()) != NULL) {
 281       // A list of paths. Search for the path that contains the library.
 282       int n;
 283       char** pelements = split_path(pname, &n);
 284       if (pelements != NULL) {
 285         for (int i = 0; i < n; i++) {
 286           char* path = pelements[i];
 287           // Really shouldn't be NULL, but check can't hurt.
 288           size_t plen = (path == NULL) ? 0 : strlen(path);
 289           if (plen == 0) {
 290             continue; // Skip the empty path values.
 291           }
 292           const char lastchar = path[plen - 1];
 293           retval = conc_path_file_and_check(buffer, buffer, buflen, path, lastchar, fullfname);
 294           if (retval) break;
 295         }
 296         // Release the storage allocated by split_path.
 297         for (int i = 0; i < n; i++) {
 298           if (pelements[i] != NULL) {
 299             FREE_C_HEAP_ARRAY(char, pelements[i]);
 300           }
 301         }
 302         FREE_C_HEAP_ARRAY(char*, pelements);
 303       }
 304     } else {
 305       // A definite path.
 306       const char lastchar = pname[pnamelen-1];
 307       retval = conc_path_file_and_check(buffer, buffer, buflen, pname, lastchar, fullfname);
 308     }
 309   }
 310 
 311   FREE_C_HEAP_ARRAY(char*, fullfname);
 312   return retval;
 313 }
 314 
 315 // --------------------- sun.misc.Signal (optional) ---------------------
 316 
 317 
 318 // SIGBREAK is sent by the keyboard to query the VM state
 319 #ifndef SIGBREAK
 320 #define SIGBREAK SIGQUIT
 321 #endif
 322 
 323 // sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.
 324 
 325 
 326 static void signal_thread_entry(JavaThread* thread, TRAPS) {
 327   os::set_priority(thread, NearMaxPriority);
 328   while (true) {
 329     int sig;
 330     {
 331       // FIXME : Currently we have not decided what should be the status
 332       //         for this java thread blocked here. Once we decide about
 333       //         that we should fix this.
 334       sig = os::signal_wait();
 335     }
 336     if (sig == os::sigexitnum_pd()) {
 337        // Terminate the signal thread
 338        return;
 339     }
 340 
 341     switch (sig) {
 342       case SIGBREAK: {
 343         // Check if the signal is a trigger to start the Attach Listener - in that
 344         // case don't print stack traces.
 345         if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
 346           continue;
 347         }
 348         // Print stack traces
 349         // Any SIGBREAK operations added here should make sure to flush
 350         // the output stream (e.g. tty->flush()) after output.  See 4803766.
 351         // Each module also prints an extra carriage return after its output.
 352         VM_PrintThreads op;
 353         VMThread::execute(&op);
 354         VM_PrintJNI jni_op;
 355         VMThread::execute(&jni_op);
 356         VM_FindDeadlocks op1(tty);
 357         VMThread::execute(&op1);
 358         Universe::print_heap_at_SIGBREAK();
 359         if (PrintClassHistogram) {
 360           VM_GC_HeapInspection op1(tty, true /* force full GC before heap inspection */);
 361           VMThread::execute(&op1);
 362         }
 363         if (JvmtiExport::should_post_data_dump()) {
 364           JvmtiExport::post_data_dump();
 365         }
 366         break;
 367       }
 368       default: {
 369         // Dispatch the signal to java
 370         HandleMark hm(THREAD);
 371         Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_misc_Signal(), THREAD);
 372         if (klass != NULL) {
 373           JavaValue result(T_VOID);
 374           JavaCallArguments args;
 375           args.push_int(sig);
 376           JavaCalls::call_static(
 377             &result,
 378             klass,
 379             vmSymbols::dispatch_name(),
 380             vmSymbols::int_void_signature(),
 381             &args,
 382             THREAD
 383           );
 384         }
 385         if (HAS_PENDING_EXCEPTION) {
 386           // tty is initialized early so we don't expect it to be null, but
 387           // if it is we can't risk doing an initialization that might
 388           // trigger additional out-of-memory conditions
 389           if (tty != NULL) {
 390             char klass_name[256];
 391             char tmp_sig_name[16];
 392             const char* sig_name = "UNKNOWN";
 393             InstanceKlass::cast(PENDING_EXCEPTION->klass())->
 394               name()->as_klass_external_name(klass_name, 256);
 395             if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
 396               sig_name = tmp_sig_name;
 397             warning("Exception %s occurred dispatching signal %s to handler"
 398                     "- the VM may need to be forcibly terminated",
 399                     klass_name, sig_name );
 400           }
 401           CLEAR_PENDING_EXCEPTION;
 402         }
 403       }
 404     }
 405   }
 406 }
 407 
 408 void os::init_before_ergo() {
 409   initialize_initial_active_processor_count();
 410   // We need to initialize large page support here because ergonomics takes some
 411   // decisions depending on large page support and the calculated large page size.
 412   large_page_init();
 413 
 414   // We need to adapt the configured number of stack protection pages given
 415   // in 4K pages to the actual os page size. We must do this before setting
 416   // up minimal stack sizes etc. in os::init_2().
 417   JavaThread::set_stack_red_zone_size     (align_up(StackRedPages      * 4 * K, vm_page_size()));
 418   JavaThread::set_stack_yellow_zone_size  (align_up(StackYellowPages   * 4 * K, vm_page_size()));
 419   JavaThread::set_stack_reserved_zone_size(align_up(StackReservedPages * 4 * K, vm_page_size()));
 420   JavaThread::set_stack_shadow_zone_size  (align_up(StackShadowPages   * 4 * K, vm_page_size()));
 421 
 422   // VM version initialization identifies some characteristics of the
 423   // platform that are used during ergonomic decisions.
 424   VM_Version::init_before_ergo();
 425 }
 426 
 427 void os::signal_init(TRAPS) {
 428   if (!ReduceSignalUsage) {
 429     // Setup JavaThread for processing signals
 430     Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
 431     InstanceKlass* ik = InstanceKlass::cast(k);
 432     instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 433 
 434     const char thread_name[] = "Signal Dispatcher";
 435     Handle string = java_lang_String::create_from_str(thread_name, CHECK);
 436 
 437     // Initialize thread_oop to put it into the system threadGroup
 438     Handle thread_group (THREAD, Universe::system_thread_group());
 439     JavaValue result(T_VOID);
 440     JavaCalls::call_special(&result, thread_oop,
 441                            ik,
 442                            vmSymbols::object_initializer_name(),
 443                            vmSymbols::threadgroup_string_void_signature(),
 444                            thread_group,
 445                            string,
 446                            CHECK);
 447 
 448     Klass* group = SystemDictionary::ThreadGroup_klass();
 449     JavaCalls::call_special(&result,
 450                             thread_group,
 451                             group,
 452                             vmSymbols::add_method_name(),
 453                             vmSymbols::thread_void_signature(),
 454                             thread_oop,         // ARG 1
 455                             CHECK);
 456 
 457     os::signal_init_pd();
 458 
 459     { MutexLocker mu(Threads_lock);
 460       JavaThread* signal_thread = new JavaThread(&signal_thread_entry);
 461 
 462       // At this point it may be possible that no osthread was created for the
 463       // JavaThread due to lack of memory. We would have to throw an exception
 464       // in that case. However, since this must work and we do not allow
 465       // exceptions anyway, check and abort if this fails.
 466       if (signal_thread == NULL || signal_thread->osthread() == NULL) {
 467         vm_exit_during_initialization("java.lang.OutOfMemoryError",
 468                                       os::native_thread_creation_failed_msg());
 469       }
 470 
 471       java_lang_Thread::set_thread(thread_oop(), signal_thread);
 472       java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
 473       java_lang_Thread::set_daemon(thread_oop());
 474 
 475       signal_thread->set_threadObj(thread_oop());
 476       Threads::add(signal_thread);
 477       Thread::start(signal_thread);
 478     }
 479     // Handle ^BREAK
 480     os::signal(SIGBREAK, os::user_handler());
 481   }
 482 }
 483 
 484 
 485 void os::terminate_signal_thread() {
 486   if (!ReduceSignalUsage)
 487     signal_notify(sigexitnum_pd());
 488 }
 489 
 490 
 491 // --------------------- loading libraries ---------------------
 492 
 493 typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
 494 extern struct JavaVM_ main_vm;
 495 
 496 static void* _native_java_library = NULL;
 497 
 498 void* os::native_java_library() {
 499   if (_native_java_library == NULL) {
 500     char buffer[JVM_MAXPATHLEN];
 501     char ebuf[1024];
 502 
 503     // Try to load verify dll first. In 1.3 java dll depends on it and is not
 504     // always able to find it when the loading executable is outside the JDK.
 505     // In order to keep working with 1.2 we ignore any loading errors.
 506     if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 507                        "verify")) {
 508       dll_load(buffer, ebuf, sizeof(ebuf));
 509     }
 510 
 511     // Load java dll
 512     if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 513                        "java")) {
 514       _native_java_library = dll_load(buffer, ebuf, sizeof(ebuf));
 515     }
 516     if (_native_java_library == NULL) {
 517       vm_exit_during_initialization("Unable to load native library", ebuf);
 518     }
 519 
 520 #if defined(__OpenBSD__)
 521     // Work-around OpenBSD's lack of $ORIGIN support by pre-loading libnet.so
 522     // ignore errors
 523     if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 524                        "net")) {
 525       dll_load(buffer, ebuf, sizeof(ebuf));
 526     }
 527 #endif
 528   }
 529   return _native_java_library;
 530 }
 531 
 532 /*
 533  * Support for finding Agent_On(Un)Load/Attach<_lib_name> if it exists.
 534  * If check_lib == true then we are looking for an
 535  * Agent_OnLoad_lib_name or Agent_OnAttach_lib_name function to determine if
 536  * this library is statically linked into the image.
 537  * If check_lib == false then we will look for the appropriate symbol in the
 538  * executable if agent_lib->is_static_lib() == true or in the shared library
 539  * referenced by 'handle'.
 540  */
 541 void* os::find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 542                               const char *syms[], size_t syms_len) {
 543   assert(agent_lib != NULL, "sanity check");
 544   const char *lib_name;
 545   void *handle = agent_lib->os_lib();
 546   void *entryName = NULL;
 547   char *agent_function_name;
 548   size_t i;
 549 
 550   // If checking then use the agent name otherwise test is_static_lib() to
 551   // see how to process this lookup
 552   lib_name = ((check_lib || agent_lib->is_static_lib()) ? agent_lib->name() : NULL);
 553   for (i = 0; i < syms_len; i++) {
 554     agent_function_name = build_agent_function_name(syms[i], lib_name, agent_lib->is_absolute_path());
 555     if (agent_function_name == NULL) {
 556       break;
 557     }
 558     entryName = dll_lookup(handle, agent_function_name);
 559     FREE_C_HEAP_ARRAY(char, agent_function_name);
 560     if (entryName != NULL) {
 561       break;
 562     }
 563   }
 564   return entryName;
 565 }
 566 
 567 // See if the passed in agent is statically linked into the VM image.
 568 bool os::find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 569                             size_t syms_len) {
 570   void *ret;
 571   void *proc_handle;
 572   void *save_handle;
 573 
 574   assert(agent_lib != NULL, "sanity check");
 575   if (agent_lib->name() == NULL) {
 576     return false;
 577   }
 578   proc_handle = get_default_process_handle();
 579   // Check for Agent_OnLoad/Attach_lib_name function
 580   save_handle = agent_lib->os_lib();
 581   // We want to look in this process' symbol table.
 582   agent_lib->set_os_lib(proc_handle);
 583   ret = find_agent_function(agent_lib, true, syms, syms_len);
 584   if (ret != NULL) {
 585     // Found an entry point like Agent_OnLoad_lib_name so we have a static agent
 586     agent_lib->set_valid();
 587     agent_lib->set_static_lib(true);
 588     return true;
 589   }
 590   agent_lib->set_os_lib(save_handle);
 591   return false;
 592 }
 593 
 594 // --------------------- heap allocation utilities ---------------------
 595 
 596 char *os::strdup(const char *str, MEMFLAGS flags) {
 597   size_t size = strlen(str);
 598   char *dup_str = (char *)malloc(size + 1, flags);
 599   if (dup_str == NULL) return NULL;
 600   strcpy(dup_str, str);
 601   return dup_str;
 602 }
 603 
 604 char* os::strdup_check_oom(const char* str, MEMFLAGS flags) {
 605   char* p = os::strdup(str, flags);
 606   if (p == NULL) {
 607     vm_exit_out_of_memory(strlen(str) + 1, OOM_MALLOC_ERROR, "os::strdup_check_oom");
 608   }
 609   return p;
 610 }
 611 
 612 
 613 #define paranoid                 0  /* only set to 1 if you suspect checking code has bug */
 614 
 615 #ifdef ASSERT
 616 
 617 static void verify_memory(void* ptr) {
 618   GuardedMemory guarded(ptr);
 619   if (!guarded.verify_guards()) {
 620     tty->print_cr("## nof_mallocs = " UINT64_FORMAT ", nof_frees = " UINT64_FORMAT, os::num_mallocs, os::num_frees);
 621     tty->print_cr("## memory stomp:");
 622     guarded.print_on(tty);
 623     fatal("memory stomping error");
 624   }
 625 }
 626 
 627 #endif
 628 
 629 //
 630 // This function supports testing of the malloc out of memory
 631 // condition without really running the system out of memory.
 632 //
 633 static bool has_reached_max_malloc_test_peak(size_t alloc_size) {
 634   if (MallocMaxTestWords > 0) {
 635     jint words = (jint)(alloc_size / BytesPerWord);
 636 
 637     if ((cur_malloc_words + words) > MallocMaxTestWords) {
 638       return true;
 639     }
 640     Atomic::add(words, (volatile jint *)&cur_malloc_words);
 641   }
 642   return false;
 643 }
 644 
 645 void* os::malloc(size_t size, MEMFLAGS flags) {
 646   return os::malloc(size, flags, CALLER_PC);
 647 }
 648 
 649 void* os::malloc(size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
 650   NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
 651   NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
 652 
 653   // Since os::malloc can be called when the libjvm.{dll,so} is
 654   // first loaded and we don't have a thread yet we must accept NULL also here.
 655   assert(!os::ThreadCrashProtection::is_crash_protected(Thread::current_or_null()),
 656          "malloc() not allowed when crash protection is set");
 657 
 658   if (size == 0) {
 659     // return a valid pointer if size is zero
 660     // if NULL is returned the calling functions assume out of memory.
 661     size = 1;
 662   }
 663 
 664   // NMT support
 665   NMT_TrackingLevel level = MemTracker::tracking_level();
 666   size_t            nmt_header_size = MemTracker::malloc_header_size(level);
 667 
 668 #ifndef ASSERT
 669   const size_t alloc_size = size + nmt_header_size;
 670 #else
 671   const size_t alloc_size = GuardedMemory::get_total_size(size + nmt_header_size);
 672   if (size + nmt_header_size > alloc_size) { // Check for rollover.
 673     return NULL;
 674   }
 675 #endif
 676 
 677   // For the test flag -XX:MallocMaxTestWords
 678   if (has_reached_max_malloc_test_peak(size)) {
 679     return NULL;
 680   }
 681 
 682   u_char* ptr;
 683   ptr = (u_char*)::malloc(alloc_size);
 684 
 685 #ifdef ASSERT
 686   if (ptr == NULL) {
 687     return NULL;
 688   }
 689   // Wrap memory with guard
 690   GuardedMemory guarded(ptr, size + nmt_header_size);
 691   ptr = guarded.get_user_ptr();
 692 #endif
 693   if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
 694     tty->print_cr("os::malloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 695     breakpoint();
 696   }
 697   debug_only(if (paranoid) verify_memory(ptr));
 698   if (PrintMalloc && tty != NULL) {
 699     tty->print_cr("os::malloc " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 700   }
 701 
 702   // we do not track guard memory
 703   return MemTracker::record_malloc((address)ptr, size, memflags, stack, level);
 704 }
 705 
 706 void* os::realloc(void *memblock, size_t size, MEMFLAGS flags) {
 707   return os::realloc(memblock, size, flags, CALLER_PC);
 708 }
 709 
 710 void* os::realloc(void *memblock, size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
 711 
 712   // For the test flag -XX:MallocMaxTestWords
 713   if (has_reached_max_malloc_test_peak(size)) {
 714     return NULL;
 715   }
 716 
 717   if (size == 0) {
 718     // return a valid pointer if size is zero
 719     // if NULL is returned the calling functions assume out of memory.
 720     size = 1;
 721   }
 722 
 723 #ifndef ASSERT
 724   NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
 725   NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
 726    // NMT support
 727   void* membase = MemTracker::record_free(memblock);
 728   NMT_TrackingLevel level = MemTracker::tracking_level();
 729   size_t  nmt_header_size = MemTracker::malloc_header_size(level);
 730   void* ptr = ::realloc(membase, size + nmt_header_size);
 731   return MemTracker::record_malloc(ptr, size, memflags, stack, level);
 732 #else
 733   if (memblock == NULL) {
 734     return os::malloc(size, memflags, stack);
 735   }
 736   if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
 737     tty->print_cr("os::realloc caught " PTR_FORMAT, p2i(memblock));
 738     breakpoint();
 739   }
 740   // NMT support
 741   void* membase = MemTracker::malloc_base(memblock);
 742   verify_memory(membase);
 743   // always move the block
 744   void* ptr = os::malloc(size, memflags, stack);
 745   if (PrintMalloc && tty != NULL) {
 746     tty->print_cr("os::realloc " SIZE_FORMAT " bytes, " PTR_FORMAT " --> " PTR_FORMAT, size, p2i(memblock), p2i(ptr));
 747   }
 748   // Copy to new memory if malloc didn't fail
 749   if ( ptr != NULL ) {
 750     GuardedMemory guarded(MemTracker::malloc_base(memblock));
 751     // Guard's user data contains NMT header
 752     size_t memblock_size = guarded.get_user_size() - MemTracker::malloc_header_size(memblock);
 753     memcpy(ptr, memblock, MIN2(size, memblock_size));
 754     if (paranoid) verify_memory(MemTracker::malloc_base(ptr));
 755     if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
 756       tty->print_cr("os::realloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 757       breakpoint();
 758     }
 759     os::free(memblock);
 760   }
 761   return ptr;
 762 #endif
 763 }
 764 
 765 
 766 void  os::free(void *memblock) {
 767   NOT_PRODUCT(inc_stat_counter(&num_frees, 1));
 768 #ifdef ASSERT
 769   if (memblock == NULL) return;
 770   if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
 771     if (tty != NULL) tty->print_cr("os::free caught " PTR_FORMAT, p2i(memblock));
 772     breakpoint();
 773   }
 774   void* membase = MemTracker::record_free(memblock);
 775   verify_memory(membase);
 776 
 777   GuardedMemory guarded(membase);
 778   size_t size = guarded.get_user_size();
 779   inc_stat_counter(&free_bytes, size);
 780   membase = guarded.release_for_freeing();
 781   if (PrintMalloc && tty != NULL) {
 782       fprintf(stderr, "os::free " SIZE_FORMAT " bytes --> " PTR_FORMAT "\n", size, (uintptr_t)membase);
 783   }
 784   ::free(membase);
 785 #else
 786   void* membase = MemTracker::record_free(memblock);
 787   ::free(membase);
 788 #endif
 789 }
 790 
 791 void os::init_random(unsigned int initval) {
 792   _rand_seed = initval;
 793 }
 794 
 795 
 796 static int random_helper(unsigned int rand_seed) {
 797   /* standard, well-known linear congruential random generator with
 798    * next_rand = (16807*seed) mod (2**31-1)
 799    * see
 800    * (1) "Random Number Generators: Good Ones Are Hard to Find",
 801    *      S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
 802    * (2) "Two Fast Implementations of the 'Minimal Standard' Random
 803    *     Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
 804   */
 805   const unsigned int a = 16807;
 806   const unsigned int m = 2147483647;
 807   const int q = m / a;        assert(q == 127773, "weird math");
 808   const int r = m % a;        assert(r == 2836, "weird math");
 809 
 810   // compute az=2^31p+q
 811   unsigned int lo = a * (rand_seed & 0xFFFF);
 812   unsigned int hi = a * (rand_seed >> 16);
 813   lo += (hi & 0x7FFF) << 16;
 814 
 815   // if q overflowed, ignore the overflow and increment q
 816   if (lo > m) {
 817     lo &= m;
 818     ++lo;
 819   }
 820   lo += hi >> 15;
 821 
 822   // if (p+q) overflowed, ignore the overflow and increment (p+q)
 823   if (lo > m) {
 824     lo &= m;
 825     ++lo;
 826   }
 827   return lo;
 828 }
 829 
 830 int os::random() {
 831   // Make updating the random seed thread safe.
 832   while (true) {
 833     unsigned int seed = _rand_seed;
 834     unsigned int rand = random_helper(seed);
 835     if (Atomic::cmpxchg(rand, &_rand_seed, seed) == seed) {
 836       return static_cast<int>(rand);
 837     }
 838   }
 839 }
 840 
 841 // The INITIALIZED state is distinguished from the SUSPENDED state because the
 842 // conditions in which a thread is first started are different from those in which
 843 // a suspension is resumed.  These differences make it hard for us to apply the
 844 // tougher checks when starting threads that we want to do when resuming them.
 845 // However, when start_thread is called as a result of Thread.start, on a Java
 846 // thread, the operation is synchronized on the Java Thread object.  So there
 847 // cannot be a race to start the thread and hence for the thread to exit while
 848 // we are working on it.  Non-Java threads that start Java threads either have
 849 // to do so in a context in which races are impossible, or should do appropriate
 850 // locking.
 851 
 852 void os::start_thread(Thread* thread) {
 853   // guard suspend/resume
 854   MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
 855   OSThread* osthread = thread->osthread();
 856   osthread->set_state(RUNNABLE);
 857   pd_start_thread(thread);
 858 }
 859 
 860 void os::abort(bool dump_core) {
 861   abort(dump_core && CreateCoredumpOnCrash, NULL, NULL);
 862 }
 863 
 864 //---------------------------------------------------------------------------
 865 // Helper functions for fatal error handler
 866 
 867 void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
 868   assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");
 869 
 870   int cols = 0;
 871   int cols_per_line = 0;
 872   switch (unitsize) {
 873     case 1: cols_per_line = 16; break;
 874     case 2: cols_per_line = 8;  break;
 875     case 4: cols_per_line = 4;  break;
 876     case 8: cols_per_line = 2;  break;
 877     default: return;
 878   }
 879 
 880   address p = start;
 881   st->print(PTR_FORMAT ":   ", p2i(start));
 882   while (p < end) {
 883     switch (unitsize) {
 884       case 1: st->print("%02x", *(u1*)p); break;
 885       case 2: st->print("%04x", *(u2*)p); break;
 886       case 4: st->print("%08x", *(u4*)p); break;
 887       case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
 888     }
 889     p += unitsize;
 890     cols++;
 891     if (cols >= cols_per_line && p < end) {
 892        cols = 0;
 893        st->cr();
 894        st->print(PTR_FORMAT ":   ", p2i(p));
 895     } else {
 896        st->print(" ");
 897     }
 898   }
 899   st->cr();
 900 }
 901 
 902 void os::print_environment_variables(outputStream* st, const char** env_list) {
 903   if (env_list) {
 904     st->print_cr("Environment Variables:");
 905 
 906     for (int i = 0; env_list[i] != NULL; i++) {
 907       char *envvar = ::getenv(env_list[i]);
 908       if (envvar != NULL) {
 909         st->print("%s", env_list[i]);
 910         st->print("=");
 911         st->print_cr("%s", envvar);
 912       }
 913     }
 914   }
 915 }
 916 
 917 void os::print_cpu_info(outputStream* st, char* buf, size_t buflen) {
 918   // cpu
 919   st->print("CPU:");
 920   st->print("total %d", os::processor_count());
 921   // It's not safe to query number of active processors after crash
 922   // st->print("(active %d)", os::active_processor_count()); but we can
 923   // print the initial number of active processors.
 924   // We access the raw value here because the assert in the accessor will
 925   // fail if the crash occurs before initialization of this value.
 926   st->print(" (initial active %d)", _initial_active_processor_count);
 927   st->print(" %s", VM_Version::features_string());
 928   st->cr();
 929   pd_print_cpu_info(st, buf, buflen);
 930 }
 931 
 932 // Print a one line string summarizing the cpu, number of cores, memory, and operating system version
 933 void os::print_summary_info(outputStream* st, char* buf, size_t buflen) {
 934   st->print("Host: ");
 935 #ifndef PRODUCT
 936   if (get_host_name(buf, buflen)) {
 937     st->print("%s, ", buf);
 938   }
 939 #endif // PRODUCT
 940   get_summary_cpu_info(buf, buflen);
 941   st->print("%s, ", buf);
 942   size_t mem = physical_memory()/G;
 943   if (mem == 0) {  // for low memory systems
 944     mem = physical_memory()/M;
 945     st->print("%d cores, " SIZE_FORMAT "M, ", processor_count(), mem);
 946   } else {
 947     st->print("%d cores, " SIZE_FORMAT "G, ", processor_count(), mem);
 948   }
 949   get_summary_os_info(buf, buflen);
 950   st->print_raw(buf);
 951   st->cr();
 952 }
 953 
 954 void os::print_date_and_time(outputStream *st, char* buf, size_t buflen) {
 955   const int secs_per_day  = 86400;
 956   const int secs_per_hour = 3600;
 957   const int secs_per_min  = 60;
 958 
 959   time_t tloc;
 960   (void)time(&tloc);
 961   char* timestring = ctime(&tloc);  // ctime adds newline.
 962   // edit out the newline
 963   char* nl = strchr(timestring, '\n');
 964   if (nl != NULL) {
 965     *nl = '\0';
 966   }
 967 
 968   struct tm tz;
 969   if (localtime_pd(&tloc, &tz) != NULL) {
 970     ::strftime(buf, buflen, "%Z", &tz);
 971     st->print("Time: %s %s", timestring, buf);
 972   } else {
 973     st->print("Time: %s", timestring);
 974   }
 975 
 976   double t = os::elapsedTime();
 977   // NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
 978   //       Linux. Must be a bug in glibc ? Workaround is to round "t" to int
 979   //       before printf. We lost some precision, but who cares?
 980   int eltime = (int)t;  // elapsed time in seconds
 981 
 982   // print elapsed time in a human-readable format:
 983   int eldays = eltime / secs_per_day;
 984   int day_secs = eldays * secs_per_day;
 985   int elhours = (eltime - day_secs) / secs_per_hour;
 986   int hour_secs = elhours * secs_per_hour;
 987   int elmins = (eltime - day_secs - hour_secs) / secs_per_min;
 988   int minute_secs = elmins * secs_per_min;
 989   int elsecs = (eltime - day_secs - hour_secs - minute_secs);
 990   st->print_cr(" elapsed time: %d seconds (%dd %dh %dm %ds)", eltime, eldays, elhours, elmins, elsecs);
 991 }
 992 
 993 // moved from debug.cpp (used to be find()) but still called from there
 994 // The verbose parameter is only set by the debug code in one case
 995 void os::print_location(outputStream* st, intptr_t x, bool verbose) {
 996   address addr = (address)x;
 997   CodeBlob* b = CodeCache::find_blob_unsafe(addr);
 998   if (b != NULL) {
 999     if (b->is_buffer_blob()) {
1000       // the interpreter is generated into a buffer blob
1001       InterpreterCodelet* i = Interpreter::codelet_containing(addr);
1002       if (i != NULL) {
1003         st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an Interpreter codelet", p2i(addr), (int)(addr - i->code_begin()));
1004         i->print_on(st);
1005         return;
1006       }
1007       if (Interpreter::contains(addr)) {
1008         st->print_cr(INTPTR_FORMAT " is pointing into interpreter code"
1009                      " (not bytecode specific)", p2i(addr));
1010         return;
1011       }
1012       //
1013       if (AdapterHandlerLibrary::contains(b)) {
1014         st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an AdapterHandler", p2i(addr), (int)(addr - b->code_begin()));
1015         AdapterHandlerLibrary::print_handler_on(st, b);
1016       }
1017       // the stubroutines are generated into a buffer blob
1018       StubCodeDesc* d = StubCodeDesc::desc_for(addr);
1019       if (d != NULL) {
1020         st->print_cr(INTPTR_FORMAT " is at begin+%d in a stub", p2i(addr), (int)(addr - d->begin()));
1021         d->print_on(st);
1022         st->cr();
1023         return;
1024       }
1025       if (StubRoutines::contains(addr)) {
1026         st->print_cr(INTPTR_FORMAT " is pointing to an (unnamed) stub routine", p2i(addr));
1027         return;
1028       }
1029       // the InlineCacheBuffer is using stubs generated into a buffer blob
1030       if (InlineCacheBuffer::contains(addr)) {
1031         st->print_cr(INTPTR_FORMAT " is pointing into InlineCacheBuffer", p2i(addr));
1032         return;
1033       }
1034       VtableStub* v = VtableStubs::stub_containing(addr);
1035       if (v != NULL) {
1036         st->print_cr(INTPTR_FORMAT " is at entry_point+%d in a vtable stub", p2i(addr), (int)(addr - v->entry_point()));
1037         v->print_on(st);
1038         st->cr();
1039         return;
1040       }
1041     }
1042     nmethod* nm = b->as_nmethod_or_null();
1043     if (nm != NULL) {
1044       ResourceMark rm;
1045       st->print(INTPTR_FORMAT " is at entry_point+%d in (nmethod*)" INTPTR_FORMAT,
1046                 p2i(addr), (int)(addr - nm->entry_point()), p2i(nm));
1047       if (verbose) {
1048         st->print(" for ");
1049         nm->method()->print_value_on(st);
1050       }
1051       st->cr();
1052       nm->print_nmethod(verbose);
1053       return;
1054     }
1055     st->print_cr(INTPTR_FORMAT " is at code_begin+%d in ", p2i(addr), (int)(addr - b->code_begin()));
1056     b->print_on(st);
1057     return;
1058   }
1059 
1060   if (Universe::heap()->is_in(addr)) {
1061     HeapWord* p = Universe::heap()->block_start(addr);
1062     bool print = false;
1063     // If we couldn't find it it just may mean that heap wasn't parsable
1064     // See if we were just given an oop directly
1065     if (p != NULL && Universe::heap()->block_is_obj(p)) {
1066       print = true;
1067     } else if (p == NULL && oopDesc::is_oop(oop(addr))) {
1068       p = (HeapWord*) addr;
1069       print = true;
1070     }
1071     if (print) {
1072       if (p == (HeapWord*) addr) {
1073         st->print_cr(INTPTR_FORMAT " is an oop", p2i(addr));
1074       } else {
1075         st->print_cr(INTPTR_FORMAT " is pointing into object: " INTPTR_FORMAT, p2i(addr), p2i(p));
1076       }
1077       oop(p)->print_on(st);
1078       return;
1079     }
1080   } else {
1081     if (Universe::heap()->is_in_reserved(addr)) {
1082       st->print_cr(INTPTR_FORMAT " is an unallocated location "
1083                    "in the heap", p2i(addr));
1084       return;
1085     }
1086   }
1087   if (JNIHandles::is_global_handle((jobject) addr)) {
1088     st->print_cr(INTPTR_FORMAT " is a global jni handle", p2i(addr));
1089     return;
1090   }
1091   if (JNIHandles::is_weak_global_handle((jobject) addr)) {
1092     st->print_cr(INTPTR_FORMAT " is a weak global jni handle", p2i(addr));
1093     return;
1094   }
1095 #ifndef PRODUCT
1096   // we don't keep the block list in product mode
1097   if (JNIHandleBlock::any_contains((jobject) addr)) {
1098     st->print_cr(INTPTR_FORMAT " is a local jni handle", p2i(addr));
1099     return;
1100   }
1101 #endif
1102 
1103   for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
1104     // Check for privilege stack
1105     if (thread->privileged_stack_top() != NULL &&
1106         thread->privileged_stack_top()->contains(addr)) {
1107       st->print_cr(INTPTR_FORMAT " is pointing into the privilege stack "
1108                    "for thread: " INTPTR_FORMAT, p2i(addr), p2i(thread));
1109       if (verbose) thread->print_on(st);
1110       return;
1111     }
1112     // If the addr is a java thread print information about that.
1113     if (addr == (address)thread) {
1114       if (verbose) {
1115         thread->print_on(st);
1116       } else {
1117         st->print_cr(INTPTR_FORMAT " is a thread", p2i(addr));
1118       }
1119       return;
1120     }
1121     // If the addr is in the stack region for this thread then report that
1122     // and print thread info
1123     if (thread->on_local_stack(addr)) {
1124       st->print_cr(INTPTR_FORMAT " is pointing into the stack for thread: "
1125                    INTPTR_FORMAT, p2i(addr), p2i(thread));
1126       if (verbose) thread->print_on(st);
1127       return;
1128     }
1129 
1130   }
1131 
1132   // Check if in metaspace and print types that have vptrs (only method now)
1133   if (Metaspace::contains(addr)) {
1134     if (Method::has_method_vptr((const void*)addr)) {
1135       ((Method*)addr)->print_value_on(st);
1136       st->cr();
1137     } else {
1138       // Use addr->print() from the debugger instead (not here)
1139       st->print_cr(INTPTR_FORMAT " is pointing into metadata", p2i(addr));
1140     }
1141     return;
1142   }
1143 
1144   // Try an OS specific find
1145   if (os::find(addr, st)) {
1146     return;
1147   }
1148 
1149   st->print_cr(INTPTR_FORMAT " is an unknown value", p2i(addr));
1150 }
1151 
1152 // Looks like all platforms except IA64 can use the same function to check
1153 // if C stack is walkable beyond current frame. The check for fp() is not
1154 // necessary on Sparc, but it's harmless.
1155 bool os::is_first_C_frame(frame* fr) {
1156 #if (defined(IA64) && !defined(AIX)) && !defined(_WIN32)
1157   // On IA64 we have to check if the callers bsp is still valid
1158   // (i.e. within the register stack bounds).
1159   // Notice: this only works for threads created by the VM and only if
1160   // we walk the current stack!!! If we want to be able to walk
1161   // arbitrary other threads, we'll have to somehow store the thread
1162   // object in the frame.
1163   Thread *thread = Thread::current();
1164   if ((address)fr->fp() <=
1165       thread->register_stack_base() HPUX_ONLY(+ 0x0) LINUX_ONLY(+ 0x50)) {
1166     // This check is a little hacky, because on Linux the first C
1167     // frame's ('start_thread') register stack frame starts at
1168     // "register_stack_base + 0x48" while on HPUX, the first C frame's
1169     // ('__pthread_bound_body') register stack frame seems to really
1170     // start at "register_stack_base".
1171     return true;
1172   } else {
1173     return false;
1174   }
1175 #elif defined(IA64) && defined(_WIN32)
1176   return true;
1177 #else
1178   // Load up sp, fp, sender sp and sender fp, check for reasonable values.
1179   // Check usp first, because if that's bad the other accessors may fault
1180   // on some architectures.  Ditto ufp second, etc.
1181   uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
1182   // sp on amd can be 32 bit aligned.
1183   uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);
1184 
1185   uintptr_t usp    = (uintptr_t)fr->sp();
1186   if ((usp & sp_align_mask) != 0) return true;
1187 
1188   uintptr_t ufp    = (uintptr_t)fr->fp();
1189   if ((ufp & fp_align_mask) != 0) return true;
1190 
1191   uintptr_t old_sp = (uintptr_t)fr->sender_sp();
1192   if ((old_sp & sp_align_mask) != 0) return true;
1193   if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;
1194 
1195   uintptr_t old_fp = (uintptr_t)fr->link();
1196   if ((old_fp & fp_align_mask) != 0) return true;
1197   if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;
1198 
1199   // stack grows downwards; if old_fp is below current fp or if the stack
1200   // frame is too large, either the stack is corrupted or fp is not saved
1201   // on stack (i.e. on x86, ebp may be used as general register). The stack
1202   // is not walkable beyond current frame.
1203   if (old_fp < ufp) return true;
1204   if (old_fp - ufp > 64 * K) return true;
1205 
1206   return false;
1207 #endif
1208 }
1209 
1210 
1211 // Set up the boot classpath.
1212 
1213 char* os::format_boot_path(const char* format_string,
1214                            const char* home,
1215                            int home_len,
1216                            char fileSep,
1217                            char pathSep) {
1218     assert((fileSep == '/' && pathSep == ':') ||
1219            (fileSep == '\\' && pathSep == ';'), "unexpected separator chars");
1220 
1221     // Scan the format string to determine the length of the actual
1222     // boot classpath, and handle platform dependencies as well.
1223     int formatted_path_len = 0;
1224     const char* p;
1225     for (p = format_string; *p != 0; ++p) {
1226         if (*p == '%') formatted_path_len += home_len - 1;
1227         ++formatted_path_len;
1228     }
1229 
1230     char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1, mtInternal);
1231     if (formatted_path == NULL) {
1232         return NULL;
1233     }
1234 
1235     // Create boot classpath from format, substituting separator chars and
1236     // java home directory.
1237     char* q = formatted_path;
1238     for (p = format_string; *p != 0; ++p) {
1239         switch (*p) {
1240         case '%':
1241             strcpy(q, home);
1242             q += home_len;
1243             break;
1244         case '/':
1245             *q++ = fileSep;
1246             break;
1247         case ':':
1248             *q++ = pathSep;
1249             break;
1250         default:
1251             *q++ = *p;
1252         }
1253     }
1254     *q = '\0';
1255 
1256     assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
1257     return formatted_path;
1258 }
1259 
1260 bool os::set_boot_path(char fileSep, char pathSep) {
1261   const char* home = Arguments::get_java_home();
1262   int home_len = (int)strlen(home);
1263 
1264   struct stat st;
1265 
1266   // modular image if "modules" jimage exists
1267   char* jimage = format_boot_path("%/lib/" MODULES_IMAGE_NAME, home, home_len, fileSep, pathSep);
1268   if (jimage == NULL) return false;
1269   bool has_jimage = (os::stat(jimage, &st) == 0);
1270   if (has_jimage) {
1271     Arguments::set_sysclasspath(jimage, true);
1272     FREE_C_HEAP_ARRAY(char, jimage);
1273     return true;
1274   }
1275   FREE_C_HEAP_ARRAY(char, jimage);
1276 
1277   // check if developer build with exploded modules
1278   char* base_classes = format_boot_path("%/modules/" JAVA_BASE_NAME, home, home_len, fileSep, pathSep);
1279   if (base_classes == NULL) return false;
1280   if (os::stat(base_classes, &st) == 0) {
1281     Arguments::set_sysclasspath(base_classes, false);
1282     FREE_C_HEAP_ARRAY(char, base_classes);
1283     return true;
1284   }
1285   FREE_C_HEAP_ARRAY(char, base_classes);
1286 
1287   return false;
1288 }
1289 
1290 /*
1291  * Splits a path, based on its separator, the number of
1292  * elements is returned back in n.
1293  * It is the callers responsibility to:
1294  *   a> check the value of n, and n may be 0.
1295  *   b> ignore any empty path elements
1296  *   c> free up the data.
1297  */
1298 char** os::split_path(const char* path, int* n) {
1299   *n = 0;
1300   if (path == NULL || strlen(path) == 0) {
1301     return NULL;
1302   }
1303   const char psepchar = *os::path_separator();
1304   char* inpath = (char*)NEW_C_HEAP_ARRAY(char, strlen(path) + 1, mtInternal);
1305   if (inpath == NULL) {
1306     return NULL;
1307   }
1308   strcpy(inpath, path);
1309   int count = 1;
1310   char* p = strchr(inpath, psepchar);
1311   // Get a count of elements to allocate memory
1312   while (p != NULL) {
1313     count++;
1314     p++;
1315     p = strchr(p, psepchar);
1316   }
1317   char** opath = (char**) NEW_C_HEAP_ARRAY(char*, count, mtInternal);
1318   if (opath == NULL) {
1319     return NULL;
1320   }
1321 
1322   // do the actual splitting
1323   p = inpath;
1324   for (int i = 0 ; i < count ; i++) {
1325     size_t len = strcspn(p, os::path_separator());
1326     if (len > JVM_MAXPATHLEN) {
1327       return NULL;
1328     }
1329     // allocate the string and add terminator storage
1330     char* s  = (char*)NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
1331     if (s == NULL) {
1332       return NULL;
1333     }
1334     strncpy(s, p, len);
1335     s[len] = '\0';
1336     opath[i] = s;
1337     p += len + 1;
1338   }
1339   FREE_C_HEAP_ARRAY(char, inpath);
1340   *n = count;
1341   return opath;
1342 }
1343 
1344 void os::set_memory_serialize_page(address page) {
1345   int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
1346   _mem_serialize_page = (volatile int32_t *)page;
1347   // We initialize the serialization page shift count here
1348   // We assume a cache line size of 64 bytes
1349   assert(SerializePageShiftCount == count, "JavaThread size changed; "
1350          "SerializePageShiftCount constant should be %d", count);
1351   set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
1352 }
1353 
1354 static volatile intptr_t SerializePageLock = 0;
1355 
1356 // This method is called from signal handler when SIGSEGV occurs while the current
1357 // thread tries to store to the "read-only" memory serialize page during state
1358 // transition.
1359 void os::block_on_serialize_page_trap() {
1360   log_debug(safepoint)("Block until the serialize page permission restored");
1361 
1362   // When VMThread is holding the SerializePageLock during modifying the
1363   // access permission of the memory serialize page, the following call
1364   // will block until the permission of that page is restored to rw.
1365   // Generally, it is unsafe to manipulate locks in signal handlers, but in
1366   // this case, it's OK as the signal is synchronous and we know precisely when
1367   // it can occur.
1368   Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
1369   Thread::muxRelease(&SerializePageLock);
1370 }
1371 
1372 // Serialize all thread state variables
1373 void os::serialize_thread_states() {
1374   // On some platforms such as Solaris & Linux, the time duration of the page
1375   // permission restoration is observed to be much longer than expected  due to
1376   // scheduler starvation problem etc. To avoid the long synchronization
1377   // time and expensive page trap spinning, 'SerializePageLock' is used to block
1378   // the mutator thread if such case is encountered. See bug 6546278 for details.
1379   Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
1380   os::protect_memory((char *)os::get_memory_serialize_page(),
1381                      os::vm_page_size(), MEM_PROT_READ);
1382   os::protect_memory((char *)os::get_memory_serialize_page(),
1383                      os::vm_page_size(), MEM_PROT_RW);
1384   Thread::muxRelease(&SerializePageLock);
1385 }
1386 
1387 // Returns true if the current stack pointer is above the stack shadow
1388 // pages, false otherwise.
1389 bool os::stack_shadow_pages_available(Thread *thread, const methodHandle& method, address sp) {
1390   if (!thread->is_Java_thread()) return false;
1391   // Check if we have StackShadowPages above the yellow zone.  This parameter
1392   // is dependent on the depth of the maximum VM call stack possible from
1393   // the handler for stack overflow.  'instanceof' in the stack overflow
1394   // handler or a println uses at least 8k stack of VM and native code
1395   // respectively.
1396   const int framesize_in_bytes =
1397     Interpreter::size_top_interpreter_activation(method()) * wordSize;
1398 
1399   address limit = ((JavaThread*)thread)->stack_end() +
1400                   (JavaThread::stack_guard_zone_size() + JavaThread::stack_shadow_zone_size());
1401 
1402   return sp > (limit + framesize_in_bytes);
1403 }
1404 
1405 size_t os::page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned) {
1406   assert(min_pages > 0, "sanity");
1407   if (UseLargePages) {
1408     const size_t max_page_size = region_size / min_pages;
1409 
1410     for (size_t i = 0; _page_sizes[i] != 0; ++i) {
1411       const size_t page_size = _page_sizes[i];
1412       if (page_size <= max_page_size) {
1413         if (!must_be_aligned || is_aligned(region_size, page_size)) {
1414           return page_size;
1415         }
1416       }
1417     }
1418   }
1419 
1420   return vm_page_size();
1421 }
1422 
1423 size_t os::page_size_for_region_aligned(size_t region_size, size_t min_pages) {
1424   return page_size_for_region(region_size, min_pages, true);
1425 }
1426 
1427 size_t os::page_size_for_region_unaligned(size_t region_size, size_t min_pages) {
1428   return page_size_for_region(region_size, min_pages, false);
1429 }
1430 
1431 static const char* errno_to_string (int e, bool short_text) {
1432   #define ALL_SHARED_ENUMS(X) \
1433     X(E2BIG, "Argument list too long") \
1434     X(EACCES, "Permission denied") \
1435     X(EADDRINUSE, "Address in use") \
1436     X(EADDRNOTAVAIL, "Address not available") \
1437     X(EAFNOSUPPORT, "Address family not supported") \
1438     X(EAGAIN, "Resource unavailable, try again") \
1439     X(EALREADY, "Connection already in progress") \
1440     X(EBADF, "Bad file descriptor") \
1441     X(EBADMSG, "Bad message") \
1442     X(EBUSY, "Device or resource busy") \
1443     X(ECANCELED, "Operation canceled") \
1444     X(ECHILD, "No child processes") \
1445     X(ECONNABORTED, "Connection aborted") \
1446     X(ECONNREFUSED, "Connection refused") \
1447     X(ECONNRESET, "Connection reset") \
1448     X(EDEADLK, "Resource deadlock would occur") \
1449     X(EDESTADDRREQ, "Destination address required") \
1450     X(EDOM, "Mathematics argument out of domain of function") \
1451     X(EEXIST, "File exists") \
1452     X(EFAULT, "Bad address") \
1453     X(EFBIG, "File too large") \
1454     X(EHOSTUNREACH, "Host is unreachable") \
1455     X(EIDRM, "Identifier removed") \
1456     X(EILSEQ, "Illegal byte sequence") \
1457     X(EINPROGRESS, "Operation in progress") \
1458     X(EINTR, "Interrupted function") \
1459     X(EINVAL, "Invalid argument") \
1460     X(EIO, "I/O error") \
1461     X(EISCONN, "Socket is connected") \
1462     X(EISDIR, "Is a directory") \
1463     X(ELOOP, "Too many levels of symbolic links") \
1464     X(EMFILE, "Too many open files") \
1465     X(EMLINK, "Too many links") \
1466     X(EMSGSIZE, "Message too large") \
1467     X(ENAMETOOLONG, "Filename too long") \
1468     X(ENETDOWN, "Network is down") \
1469     X(ENETRESET, "Connection aborted by network") \
1470     X(ENETUNREACH, "Network unreachable") \
1471     X(ENFILE, "Too many files open in system") \
1472     X(ENOBUFS, "No buffer space available") \
1473     X(ENODATA, "No message is available on the STREAM head read queue") \
1474     X(ENODEV, "No such device") \
1475     X(ENOENT, "No such file or directory") \
1476     X(ENOEXEC, "Executable file format error") \
1477     X(ENOLCK, "No locks available") \
1478     X(ENOLINK, "Reserved") \
1479     X(ENOMEM, "Not enough space") \
1480     X(ENOMSG, "No message of the desired type") \
1481     X(ENOPROTOOPT, "Protocol not available") \
1482     X(ENOSPC, "No space left on device") \
1483     X(ENOSR, "No STREAM resources") \
1484     X(ENOSTR, "Not a STREAM") \
1485     X(ENOSYS, "Function not supported") \
1486     X(ENOTCONN, "The socket is not connected") \
1487     X(ENOTDIR, "Not a directory") \
1488     X(ENOTEMPTY, "Directory not empty") \
1489     X(ENOTSOCK, "Not a socket") \
1490     X(ENOTSUP, "Not supported") \
1491     X(ENOTTY, "Inappropriate I/O control operation") \
1492     X(ENXIO, "No such device or address") \
1493     X(EOPNOTSUPP, "Operation not supported on socket") \
1494     X(EOVERFLOW, "Value too large to be stored in data type") \
1495     X(EPERM, "Operation not permitted") \
1496     X(EPIPE, "Broken pipe") \
1497     X(EPROTO, "Protocol error") \
1498     X(EPROTONOSUPPORT, "Protocol not supported") \
1499     X(EPROTOTYPE, "Protocol wrong type for socket") \
1500     X(ERANGE, "Result too large") \
1501     X(EROFS, "Read-only file system") \
1502     X(ESPIPE, "Invalid seek") \
1503     X(ESRCH, "No such process") \
1504     X(ETIME, "Stream ioctl() timeout") \
1505     X(ETIMEDOUT, "Connection timed out") \
1506     X(ETXTBSY, "Text file busy") \
1507     X(EWOULDBLOCK, "Operation would block") \
1508     X(EXDEV, "Cross-device link")
1509 
1510   #define DEFINE_ENTRY(e, text) { e, #e, text },
1511 
1512   static const struct {
1513     int v;
1514     const char* short_text;
1515     const char* long_text;
1516   } table [] = {
1517 
1518     ALL_SHARED_ENUMS(DEFINE_ENTRY)
1519 
1520     // The following enums are not defined on all platforms.
1521     #ifdef ESTALE
1522     DEFINE_ENTRY(ESTALE, "Reserved")
1523     #endif
1524     #ifdef EDQUOT
1525     DEFINE_ENTRY(EDQUOT, "Reserved")
1526     #endif
1527     #ifdef EMULTIHOP
1528     DEFINE_ENTRY(EMULTIHOP, "Reserved")
1529     #endif
1530 
1531     // End marker.
1532     { -1, "Unknown errno", "Unknown error" }
1533 
1534   };
1535 
1536   #undef DEFINE_ENTRY
1537   #undef ALL_FLAGS
1538 
1539   int i = 0;
1540   while (table[i].v != -1 && table[i].v != e) {
1541     i ++;
1542   }
1543 
1544   return short_text ? table[i].short_text : table[i].long_text;
1545 
1546 }
1547 
1548 const char* os::strerror(int e) {
1549   return errno_to_string(e, false);
1550 }
1551 
1552 const char* os::errno_name(int e) {
1553   return errno_to_string(e, true);
1554 }
1555 
1556 void os::trace_page_sizes(const char* str, const size_t* page_sizes, int count) {
1557   LogTarget(Info, pagesize) log;
1558   if (log.is_enabled()) {
1559     LogStream out(log);
1560 
1561     out.print("%s: ", str);
1562     for (int i = 0; i < count; ++i) {
1563       out.print(" " SIZE_FORMAT, page_sizes[i]);
1564     }
1565     out.cr();
1566   }
1567 }
1568 
1569 #define trace_page_size_params(size) byte_size_in_exact_unit(size), exact_unit_for_byte_size(size)
1570 
1571 void os::trace_page_sizes(const char* str,
1572                           const size_t region_min_size,
1573                           const size_t region_max_size,
1574                           const size_t page_size,
1575                           const char* base,
1576                           const size_t size) {
1577 
1578   log_info(pagesize)("%s: "
1579                      " min=" SIZE_FORMAT "%s"
1580                      " max=" SIZE_FORMAT "%s"
1581                      " base=" PTR_FORMAT
1582                      " page_size=" SIZE_FORMAT "%s"
1583                      " size=" SIZE_FORMAT "%s",
1584                      str,
1585                      trace_page_size_params(region_min_size),
1586                      trace_page_size_params(region_max_size),
1587                      p2i(base),
1588                      trace_page_size_params(page_size),
1589                      trace_page_size_params(size));
1590 }
1591 
1592 void os::trace_page_sizes_for_requested_size(const char* str,
1593                                              const size_t requested_size,
1594                                              const size_t page_size,
1595                                              const size_t alignment,
1596                                              const char* base,
1597                                              const size_t size) {
1598 
1599   log_info(pagesize)("%s:"
1600                      " req_size=" SIZE_FORMAT "%s"
1601                      " base=" PTR_FORMAT
1602                      " page_size=" SIZE_FORMAT "%s"
1603                      " alignment=" SIZE_FORMAT "%s"
1604                      " size=" SIZE_FORMAT "%s",
1605                      str,
1606                      trace_page_size_params(requested_size),
1607                      p2i(base),
1608                      trace_page_size_params(page_size),
1609                      trace_page_size_params(alignment),
1610                      trace_page_size_params(size));
1611 }
1612 
1613 
1614 // This is the working definition of a server class machine:
1615 // >= 2 physical CPU's and >=2GB of memory, with some fuzz
1616 // because the graphics memory (?) sometimes masks physical memory.
1617 // If you want to change the definition of a server class machine
1618 // on some OS or platform, e.g., >=4GB on Windows platforms,
1619 // then you'll have to parameterize this method based on that state,
1620 // as was done for logical processors here, or replicate and
1621 // specialize this method for each platform.  (Or fix os to have
1622 // some inheritance structure and use subclassing.  Sigh.)
1623 // If you want some platform to always or never behave as a server
1624 // class machine, change the setting of AlwaysActAsServerClassMachine
1625 // and NeverActAsServerClassMachine in globals*.hpp.
1626 bool os::is_server_class_machine() {
1627   // First check for the early returns
1628   if (NeverActAsServerClassMachine) {
1629     return false;
1630   }
1631   if (AlwaysActAsServerClassMachine) {
1632     return true;
1633   }
1634   // Then actually look at the machine
1635   bool         result            = false;
1636   const unsigned int    server_processors = 2;
1637   const julong server_memory     = 2UL * G;
1638   // We seem not to get our full complement of memory.
1639   //     We allow some part (1/8?) of the memory to be "missing",
1640   //     based on the sizes of DIMMs, and maybe graphics cards.
1641   const julong missing_memory   = 256UL * M;
1642 
1643   /* Is this a server class machine? */
1644   if ((os::active_processor_count() >= (int)server_processors) &&
1645       (os::physical_memory() >= (server_memory - missing_memory))) {
1646     const unsigned int logical_processors =
1647       VM_Version::logical_processors_per_package();
1648     if (logical_processors > 1) {
1649       const unsigned int physical_packages =
1650         os::active_processor_count() / logical_processors;
1651       if (physical_packages >= server_processors) {
1652         result = true;
1653       }
1654     } else {
1655       result = true;
1656     }
1657   }
1658   return result;
1659 }
1660 
1661 void os::initialize_initial_active_processor_count() {
1662   assert(_initial_active_processor_count == 0, "Initial active processor count already set.");
1663   _initial_active_processor_count = active_processor_count();
1664   log_debug(os)("Initial active processor count set to %d" , _initial_active_processor_count);
1665 }
1666 
1667 void os::SuspendedThreadTask::run() {
1668   assert(Threads_lock->owned_by_self() || (_thread == VMThread::vm_thread()), "must have threads lock to call this");
1669   internal_do_task();
1670   _done = true;
1671 }
1672 
1673 bool os::create_stack_guard_pages(char* addr, size_t bytes) {
1674   return os::pd_create_stack_guard_pages(addr, bytes);
1675 }
1676 
1677 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint) {
1678   char* result = pd_reserve_memory(bytes, addr, alignment_hint);
1679   if (result != NULL) {
1680     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1681   }
1682 
1683   return result;
1684 }
1685 
1686 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint,
1687    MEMFLAGS flags) {
1688   char* result = pd_reserve_memory(bytes, addr, alignment_hint);
1689   if (result != NULL) {
1690     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1691     MemTracker::record_virtual_memory_type((address)result, flags);
1692   }
1693 
1694   return result;
1695 }
1696 
1697 char* os::attempt_reserve_memory_at(size_t bytes, char* addr) {
1698   char* result = pd_attempt_reserve_memory_at(bytes, addr);
1699   if (result != NULL) {
1700     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1701   }
1702   return result;
1703 }
1704 
1705 void os::split_reserved_memory(char *base, size_t size,
1706                                  size_t split, bool realloc) {
1707   pd_split_reserved_memory(base, size, split, realloc);
1708 }
1709 
1710 bool os::commit_memory(char* addr, size_t bytes, bool executable) {
1711   bool res = pd_commit_memory(addr, bytes, executable);
1712   if (res) {
1713     MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1714   }
1715   return res;
1716 }
1717 
1718 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint,
1719                               bool executable) {
1720   bool res = os::pd_commit_memory(addr, size, alignment_hint, executable);
1721   if (res) {
1722     MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1723   }
1724   return res;
1725 }
1726 
1727 void os::commit_memory_or_exit(char* addr, size_t bytes, bool executable,
1728                                const char* mesg) {
1729   pd_commit_memory_or_exit(addr, bytes, executable, mesg);
1730   MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1731 }
1732 
1733 void os::commit_memory_or_exit(char* addr, size_t size, size_t alignment_hint,
1734                                bool executable, const char* mesg) {
1735   os::pd_commit_memory_or_exit(addr, size, alignment_hint, executable, mesg);
1736   MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1737 }
1738 
1739 bool os::uncommit_memory(char* addr, size_t bytes) {
1740   bool res;
1741   if (MemTracker::tracking_level() > NMT_minimal) {
1742     Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
1743     res = pd_uncommit_memory(addr, bytes);
1744     if (res) {
1745       tkr.record((address)addr, bytes);
1746     }
1747   } else {
1748     res = pd_uncommit_memory(addr, bytes);
1749   }
1750   return res;
1751 }
1752 
1753 bool os::release_memory(char* addr, size_t bytes) {
1754   bool res;
1755   if (MemTracker::tracking_level() > NMT_minimal) {
1756     Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
1757     res = pd_release_memory(addr, bytes);
1758     if (res) {
1759       tkr.record((address)addr, bytes);
1760     }
1761   } else {
1762     res = pd_release_memory(addr, bytes);
1763   }
1764   return res;
1765 }
1766 
1767 void os::pretouch_memory(void* start, void* end, size_t page_size) {
1768   for (volatile char *p = (char*)start; p < (char*)end; p += page_size) {
1769     *p = 0;
1770   }
1771 }
1772 
1773 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
1774                            char *addr, size_t bytes, bool read_only,
1775                            bool allow_exec) {
1776   char* result = pd_map_memory(fd, file_name, file_offset, addr, bytes, read_only, allow_exec);
1777   if (result != NULL) {
1778     MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
1779   }
1780   return result;
1781 }
1782 
1783 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
1784                              char *addr, size_t bytes, bool read_only,
1785                              bool allow_exec) {
1786   return pd_remap_memory(fd, file_name, file_offset, addr, bytes,
1787                     read_only, allow_exec);
1788 }
1789 
1790 bool os::unmap_memory(char *addr, size_t bytes) {
1791   bool result;
1792   if (MemTracker::tracking_level() > NMT_minimal) {
1793     Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
1794     result = pd_unmap_memory(addr, bytes);
1795     if (result) {
1796       tkr.record((address)addr, bytes);
1797     }
1798   } else {
1799     result = pd_unmap_memory(addr, bytes);
1800   }
1801   return result;
1802 }
1803 
1804 void os::free_memory(char *addr, size_t bytes, size_t alignment_hint) {
1805   pd_free_memory(addr, bytes, alignment_hint);
1806 }
1807 
1808 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
1809   pd_realign_memory(addr, bytes, alignment_hint);
1810 }
1811 
1812 #ifndef _WINDOWS
1813 /* try to switch state from state "from" to state "to"
1814  * returns the state set after the method is complete
1815  */
1816 os::SuspendResume::State os::SuspendResume::switch_state(os::SuspendResume::State from,
1817                                                          os::SuspendResume::State to)
1818 {
1819   os::SuspendResume::State result =
1820     (os::SuspendResume::State) Atomic::cmpxchg((jint) to, (jint *) &_state, (jint) from);
1821   if (result == from) {
1822     // success
1823     return to;
1824   }
1825   return result;
1826 }
1827 #endif