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 "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/moduleEntry.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/icBuffer.hpp"
  33 #include "code/vtableStubs.hpp"
  34 #include "gc/shared/vmGCOperations.hpp"
  35 #include "interpreter/interpreter.hpp"
  36 #include "logging/log.hpp"
  37 #include "logging/logStream.inline.hpp"
  38 #include "memory/allocation.inline.hpp"
  39 #ifdef ASSERT
  40 #include "memory/guardedMemory.hpp"
  41 #endif
  42 #include "memory/resourceArea.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "prims/jvm.h"
  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/defaultStream.hpp"
  64 #include "utilities/events.hpp"
  65 
  66 # include <signal.h>
  67 # include <errno.h>
  68 
  69 OSThread*         os::_starting_thread    = NULL;
  70 address           os::_polling_page       = NULL;
  71 volatile int32_t* os::_mem_serialize_page = NULL;
  72 uintptr_t         os::_serialize_page_mask = 0;
  73 long              os::_rand_seed          = 1;
  74 int               os::_processor_count    = 0;
  75 int               os::_initial_active_processor_count = 0;
  76 size_t            os::_page_sizes[os::page_sizes_max];
  77 
  78 #ifndef PRODUCT
  79 julong os::num_mallocs = 0;         // # of calls to malloc/realloc
  80 julong os::alloc_bytes = 0;         // # of bytes allocated
  81 julong os::num_frees = 0;           // # of calls to free
  82 julong os::free_bytes = 0;          // # of bytes freed
  83 #endif
  84 
  85 static juint cur_malloc_words = 0;  // current size for MallocMaxTestWords
  86 
  87 void os_init_globals() {
  88   // Called from init_globals().
  89   // See Threads::create_vm() in thread.cpp, and init.cpp.
  90   os::init_globals();
  91 }
  92 
  93 // Fill in buffer with current local time as an ISO-8601 string.
  94 // E.g., yyyy-mm-ddThh:mm:ss-zzzz.
  95 // Returns buffer, or NULL if it failed.
  96 // This would mostly be a call to
  97 //     strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
  98 // except that on Windows the %z behaves badly, so we do it ourselves.
  99 // Also, people wanted milliseconds on there,
 100 // and strftime doesn't do milliseconds.
 101 char* os::iso8601_time(char* buffer, size_t buffer_length, bool utc) {
 102   // Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
 103   //                                      1         2
 104   //                             12345678901234567890123456789
 105   // format string: "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d"
 106   static const size_t needed_buffer = 29;
 107 
 108   // Sanity check the arguments
 109   if (buffer == NULL) {
 110     assert(false, "NULL buffer");
 111     return NULL;
 112   }
 113   if (buffer_length < needed_buffer) {
 114     assert(false, "buffer_length too small");
 115     return NULL;
 116   }
 117   // Get the current time
 118   jlong milliseconds_since_19700101 = javaTimeMillis();
 119   const int milliseconds_per_microsecond = 1000;
 120   const time_t seconds_since_19700101 =
 121     milliseconds_since_19700101 / milliseconds_per_microsecond;
 122   const int milliseconds_after_second =
 123     milliseconds_since_19700101 % milliseconds_per_microsecond;
 124   // Convert the time value to a tm and timezone variable
 125   struct tm time_struct;
 126   if (utc) {
 127     if (gmtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
 128       assert(false, "Failed gmtime_pd");
 129       return NULL;
 130     }
 131   } else {
 132     if (localtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
 133       assert(false, "Failed localtime_pd");
 134       return NULL;
 135     }
 136   }
 137 #if defined(_ALLBSD_SOURCE)
 138   const time_t zone = (time_t) time_struct.tm_gmtoff;
 139 #else
 140   const time_t zone = timezone;
 141 #endif
 142 
 143   // If daylight savings time is in effect,
 144   // we are 1 hour East of our time zone
 145   const time_t seconds_per_minute = 60;
 146   const time_t minutes_per_hour = 60;
 147   const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
 148   time_t UTC_to_local = zone;
 149   if (time_struct.tm_isdst > 0) {
 150     UTC_to_local = UTC_to_local - seconds_per_hour;
 151   }
 152 
 153   // No offset when dealing with UTC
 154   if (utc) {
 155     UTC_to_local = 0;
 156   }
 157 
 158   // Compute the time zone offset.
 159   //    localtime_pd() sets timezone to the difference (in seconds)
 160   //    between UTC and and local time.
 161   //    ISO 8601 says we need the difference between local time and UTC,
 162   //    we change the sign of the localtime_pd() result.
 163   const time_t local_to_UTC = -(UTC_to_local);
 164   // Then we have to figure out if if we are ahead (+) or behind (-) UTC.
 165   char sign_local_to_UTC = '+';
 166   time_t abs_local_to_UTC = local_to_UTC;
 167   if (local_to_UTC < 0) {
 168     sign_local_to_UTC = '-';
 169     abs_local_to_UTC = -(abs_local_to_UTC);
 170   }
 171   // Convert time zone offset seconds to hours and minutes.
 172   const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
 173   const time_t zone_min =
 174     ((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);
 175 
 176   // Print an ISO 8601 date and time stamp into the buffer
 177   const int year = 1900 + time_struct.tm_year;
 178   const int month = 1 + time_struct.tm_mon;
 179   const int printed = jio_snprintf(buffer, buffer_length,
 180                                    "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d",
 181                                    year,
 182                                    month,
 183                                    time_struct.tm_mday,
 184                                    time_struct.tm_hour,
 185                                    time_struct.tm_min,
 186                                    time_struct.tm_sec,
 187                                    milliseconds_after_second,
 188                                    sign_local_to_UTC,
 189                                    zone_hours,
 190                                    zone_min);
 191   if (printed == 0) {
 192     assert(false, "Failed jio_printf");
 193     return NULL;
 194   }
 195   return buffer;
 196 }
 197 
 198 OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
 199 #ifdef ASSERT
 200   if (!(!thread->is_Java_thread() ||
 201          Thread::current() == thread  ||
 202          Threads_lock->owned_by_self()
 203          || thread->is_Compiler_thread()
 204         )) {
 205     assert(false, "possibility of dangling Thread pointer");
 206   }
 207 #endif
 208 
 209   if (p >= MinPriority && p <= MaxPriority) {
 210     int priority = java_to_os_priority[p];
 211     return set_native_priority(thread, priority);
 212   } else {
 213     assert(false, "Should not happen");
 214     return OS_ERR;
 215   }
 216 }
 217 
 218 // The mapping from OS priority back to Java priority may be inexact because
 219 // Java priorities can map M:1 with native priorities. If you want the definite
 220 // Java priority then use JavaThread::java_priority()
 221 OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
 222   int p;
 223   int os_prio;
 224   OSReturn ret = get_native_priority(thread, &os_prio);
 225   if (ret != OS_OK) return ret;
 226 
 227   if (java_to_os_priority[MaxPriority] > java_to_os_priority[MinPriority]) {
 228     for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
 229   } else {
 230     // niceness values are in reverse order
 231     for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] < os_prio; p--) ;
 232   }
 233   priority = (ThreadPriority)p;
 234   return OS_OK;
 235 }
 236 
 237 
 238 // --------------------- sun.misc.Signal (optional) ---------------------
 239 
 240 
 241 // SIGBREAK is sent by the keyboard to query the VM state
 242 #ifndef SIGBREAK
 243 #define SIGBREAK SIGQUIT
 244 #endif
 245 
 246 // sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.
 247 
 248 
 249 static void signal_thread_entry(JavaThread* thread, TRAPS) {
 250   os::set_priority(thread, NearMaxPriority);
 251   while (true) {
 252     int sig;
 253     {
 254       // FIXME : Currently we have not decided what should be the status
 255       //         for this java thread blocked here. Once we decide about
 256       //         that we should fix this.
 257       sig = os::signal_wait();
 258     }
 259     if (sig == os::sigexitnum_pd()) {
 260        // Terminate the signal thread
 261        return;
 262     }
 263 
 264     switch (sig) {
 265       case SIGBREAK: {
 266         // Check if the signal is a trigger to start the Attach Listener - in that
 267         // case don't print stack traces.
 268         if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
 269           continue;
 270         }
 271         // Print stack traces
 272         // Any SIGBREAK operations added here should make sure to flush
 273         // the output stream (e.g. tty->flush()) after output.  See 4803766.
 274         // Each module also prints an extra carriage return after its output.
 275         VM_PrintThreads op;
 276         VMThread::execute(&op);
 277         VM_PrintJNI jni_op;
 278         VMThread::execute(&jni_op);
 279         VM_FindDeadlocks op1(tty);
 280         VMThread::execute(&op1);
 281         Universe::print_heap_at_SIGBREAK();
 282         if (PrintClassHistogram) {
 283           VM_GC_HeapInspection op1(tty, true /* force full GC before heap inspection */);
 284           VMThread::execute(&op1);
 285         }
 286         if (JvmtiExport::should_post_data_dump()) {
 287           JvmtiExport::post_data_dump();
 288         }
 289         break;
 290       }
 291       default: {
 292         // Dispatch the signal to java
 293         HandleMark hm(THREAD);
 294         Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_misc_Signal(), THREAD);
 295         if (klass != NULL) {
 296           JavaValue result(T_VOID);
 297           JavaCallArguments args;
 298           args.push_int(sig);
 299           JavaCalls::call_static(
 300             &result,
 301             klass,
 302             vmSymbols::dispatch_name(),
 303             vmSymbols::int_void_signature(),
 304             &args,
 305             THREAD
 306           );
 307         }
 308         if (HAS_PENDING_EXCEPTION) {
 309           // tty is initialized early so we don't expect it to be null, but
 310           // if it is we can't risk doing an initialization that might
 311           // trigger additional out-of-memory conditions
 312           if (tty != NULL) {
 313             char klass_name[256];
 314             char tmp_sig_name[16];
 315             const char* sig_name = "UNKNOWN";
 316             InstanceKlass::cast(PENDING_EXCEPTION->klass())->
 317               name()->as_klass_external_name(klass_name, 256);
 318             if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
 319               sig_name = tmp_sig_name;
 320             warning("Exception %s occurred dispatching signal %s to handler"
 321                     "- the VM may need to be forcibly terminated",
 322                     klass_name, sig_name );
 323           }
 324           CLEAR_PENDING_EXCEPTION;
 325         }
 326       }
 327     }
 328   }
 329 }
 330 
 331 void os::init_before_ergo() {
 332   initialize_initial_active_processor_count();
 333   // We need to initialize large page support here because ergonomics takes some
 334   // decisions depending on large page support and the calculated large page size.
 335   large_page_init();
 336 
 337   // We need to adapt the configured number of stack protection pages given
 338   // in 4K pages to the actual os page size. We must do this before setting
 339   // up minimal stack sizes etc. in os::init_2().
 340   JavaThread::set_stack_red_zone_size     (align_up(StackRedPages      * 4 * K, vm_page_size()));
 341   JavaThread::set_stack_yellow_zone_size  (align_up(StackYellowPages   * 4 * K, vm_page_size()));
 342   JavaThread::set_stack_reserved_zone_size(align_up(StackReservedPages * 4 * K, vm_page_size()));
 343   JavaThread::set_stack_shadow_zone_size  (align_up(StackShadowPages   * 4 * K, vm_page_size()));
 344 
 345   // VM version initialization identifies some characteristics of the
 346   // platform that are used during ergonomic decisions.
 347   VM_Version::init_before_ergo();
 348 }
 349 
 350 void os::signal_init(TRAPS) {
 351   if (!ReduceSignalUsage) {
 352     // Setup JavaThread for processing signals
 353     Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
 354     InstanceKlass* ik = InstanceKlass::cast(k);
 355     instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 356 
 357     const char thread_name[] = "Signal Dispatcher";
 358     Handle string = java_lang_String::create_from_str(thread_name, CHECK);
 359 
 360     // Initialize thread_oop to put it into the system threadGroup
 361     Handle thread_group (THREAD, Universe::system_thread_group());
 362     JavaValue result(T_VOID);
 363     JavaCalls::call_special(&result, thread_oop,
 364                            ik,
 365                            vmSymbols::object_initializer_name(),
 366                            vmSymbols::threadgroup_string_void_signature(),
 367                            thread_group,
 368                            string,
 369                            CHECK);
 370 
 371     Klass* group = SystemDictionary::ThreadGroup_klass();
 372     JavaCalls::call_special(&result,
 373                             thread_group,
 374                             group,
 375                             vmSymbols::add_method_name(),
 376                             vmSymbols::thread_void_signature(),
 377                             thread_oop,         // ARG 1
 378                             CHECK);
 379 
 380     os::signal_init_pd();
 381 
 382     { MutexLocker mu(Threads_lock);
 383       JavaThread* signal_thread = new JavaThread(&signal_thread_entry);
 384 
 385       // At this point it may be possible that no osthread was created for the
 386       // JavaThread due to lack of memory. We would have to throw an exception
 387       // in that case. However, since this must work and we do not allow
 388       // exceptions anyway, check and abort if this fails.
 389       if (signal_thread == NULL || signal_thread->osthread() == NULL) {
 390         vm_exit_during_initialization("java.lang.OutOfMemoryError",
 391                                       os::native_thread_creation_failed_msg());
 392       }
 393 
 394       java_lang_Thread::set_thread(thread_oop(), signal_thread);
 395       java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
 396       java_lang_Thread::set_daemon(thread_oop());
 397 
 398       signal_thread->set_threadObj(thread_oop());
 399       Threads::add(signal_thread);
 400       Thread::start(signal_thread);
 401     }
 402     // Handle ^BREAK
 403     os::signal(SIGBREAK, os::user_handler());
 404   }
 405 }
 406 
 407 
 408 void os::terminate_signal_thread() {
 409   if (!ReduceSignalUsage)
 410     signal_notify(sigexitnum_pd());
 411 }
 412 
 413 
 414 // --------------------- loading libraries ---------------------
 415 
 416 typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
 417 extern struct JavaVM_ main_vm;
 418 
 419 static void* _native_java_library = NULL;
 420 
 421 void* os::native_java_library() {
 422   if (_native_java_library == NULL) {
 423     char buffer[JVM_MAXPATHLEN];
 424     char ebuf[1024];
 425 
 426     // Try to load verify dll first. In 1.3 java dll depends on it and is not
 427     // always able to find it when the loading executable is outside the JDK.
 428     // In order to keep working with 1.2 we ignore any loading errors.
 429     if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 430                        "verify")) {
 431       dll_load(buffer, ebuf, sizeof(ebuf));
 432     }
 433 
 434     // Load java dll
 435     if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 436                        "java")) {
 437       _native_java_library = dll_load(buffer, ebuf, sizeof(ebuf));
 438     }
 439     if (_native_java_library == NULL) {
 440       vm_exit_during_initialization("Unable to load native library", ebuf);
 441     }
 442 
 443 #if defined(__OpenBSD__)
 444     // Work-around OpenBSD's lack of $ORIGIN support by pre-loading libnet.so
 445     // ignore errors
 446     if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
 447                        "net")) {
 448       dll_load(buffer, ebuf, sizeof(ebuf));
 449     }
 450 #endif
 451   }
 452   return _native_java_library;
 453 }
 454 
 455 /*
 456  * Support for finding Agent_On(Un)Load/Attach<_lib_name> if it exists.
 457  * If check_lib == true then we are looking for an
 458  * Agent_OnLoad_lib_name or Agent_OnAttach_lib_name function to determine if
 459  * this library is statically linked into the image.
 460  * If check_lib == false then we will look for the appropriate symbol in the
 461  * executable if agent_lib->is_static_lib() == true or in the shared library
 462  * referenced by 'handle'.
 463  */
 464 void* os::find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 465                               const char *syms[], size_t syms_len) {
 466   assert(agent_lib != NULL, "sanity check");
 467   const char *lib_name;
 468   void *handle = agent_lib->os_lib();
 469   void *entryName = NULL;
 470   char *agent_function_name;
 471   size_t i;
 472 
 473   // If checking then use the agent name otherwise test is_static_lib() to
 474   // see how to process this lookup
 475   lib_name = ((check_lib || agent_lib->is_static_lib()) ? agent_lib->name() : NULL);
 476   for (i = 0; i < syms_len; i++) {
 477     agent_function_name = build_agent_function_name(syms[i], lib_name, agent_lib->is_absolute_path());
 478     if (agent_function_name == NULL) {
 479       break;
 480     }
 481     entryName = dll_lookup(handle, agent_function_name);
 482     FREE_C_HEAP_ARRAY(char, agent_function_name);
 483     if (entryName != NULL) {
 484       break;
 485     }
 486   }
 487   return entryName;
 488 }
 489 
 490 // See if the passed in agent is statically linked into the VM image.
 491 bool os::find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 492                             size_t syms_len) {
 493   void *ret;
 494   void *proc_handle;
 495   void *save_handle;
 496 
 497   assert(agent_lib != NULL, "sanity check");
 498   if (agent_lib->name() == NULL) {
 499     return false;
 500   }
 501   proc_handle = get_default_process_handle();
 502   // Check for Agent_OnLoad/Attach_lib_name function
 503   save_handle = agent_lib->os_lib();
 504   // We want to look in this process' symbol table.
 505   agent_lib->set_os_lib(proc_handle);
 506   ret = find_agent_function(agent_lib, true, syms, syms_len);
 507   if (ret != NULL) {
 508     // Found an entry point like Agent_OnLoad_lib_name so we have a static agent
 509     agent_lib->set_valid();
 510     agent_lib->set_static_lib(true);
 511     return true;
 512   }
 513   agent_lib->set_os_lib(save_handle);
 514   return false;
 515 }
 516 
 517 // --------------------- heap allocation utilities ---------------------
 518 
 519 char *os::strdup(const char *str, MEMFLAGS flags) {
 520   size_t size = strlen(str);
 521   char *dup_str = (char *)malloc(size + 1, flags);
 522   if (dup_str == NULL) return NULL;
 523   strcpy(dup_str, str);
 524   return dup_str;
 525 }
 526 
 527 char* os::strdup_check_oom(const char* str, MEMFLAGS flags) {
 528   char* p = os::strdup(str, flags);
 529   if (p == NULL) {
 530     vm_exit_out_of_memory(strlen(str) + 1, OOM_MALLOC_ERROR, "os::strdup_check_oom");
 531   }
 532   return p;
 533 }
 534 
 535 
 536 #define paranoid                 0  /* only set to 1 if you suspect checking code has bug */
 537 
 538 #ifdef ASSERT
 539 
 540 static void verify_memory(void* ptr) {
 541   GuardedMemory guarded(ptr);
 542   if (!guarded.verify_guards()) {
 543     tty->print_cr("## nof_mallocs = " UINT64_FORMAT ", nof_frees = " UINT64_FORMAT, os::num_mallocs, os::num_frees);
 544     tty->print_cr("## memory stomp:");
 545     guarded.print_on(tty);
 546     fatal("memory stomping error");
 547   }
 548 }
 549 
 550 #endif
 551 
 552 //
 553 // This function supports testing of the malloc out of memory
 554 // condition without really running the system out of memory.
 555 //
 556 static bool has_reached_max_malloc_test_peak(size_t alloc_size) {
 557   if (MallocMaxTestWords > 0) {
 558     jint words = (jint)(alloc_size / BytesPerWord);
 559 
 560     if ((cur_malloc_words + words) > MallocMaxTestWords) {
 561       return true;
 562     }
 563     Atomic::add(words, (volatile jint *)&cur_malloc_words);
 564   }
 565   return false;
 566 }
 567 
 568 void* os::malloc(size_t size, MEMFLAGS flags) {
 569   return os::malloc(size, flags, CALLER_PC);
 570 }
 571 
 572 void* os::malloc(size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
 573   NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
 574   NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
 575 
 576 #ifdef ASSERT
 577   // checking for the WatcherThread and crash_protection first
 578   // since os::malloc can be called when the libjvm.{dll,so} is
 579   // first loaded and we don't have a thread yet.
 580   // try to find the thread after we see that the watcher thread
 581   // exists and has crash protection.
 582   WatcherThread *wt = WatcherThread::watcher_thread();
 583   if (wt != NULL && wt->has_crash_protection()) {
 584     Thread* thread = Thread::current_or_null();
 585     if (thread == wt) {
 586       assert(!wt->has_crash_protection(),
 587           "Can't malloc with crash protection from WatcherThread");
 588     }
 589   }
 590 #endif
 591 
 592   if (size == 0) {
 593     // return a valid pointer if size is zero
 594     // if NULL is returned the calling functions assume out of memory.
 595     size = 1;
 596   }
 597 
 598   // NMT support
 599   NMT_TrackingLevel level = MemTracker::tracking_level();
 600   size_t            nmt_header_size = MemTracker::malloc_header_size(level);
 601 
 602 #ifndef ASSERT
 603   const size_t alloc_size = size + nmt_header_size;
 604 #else
 605   const size_t alloc_size = GuardedMemory::get_total_size(size + nmt_header_size);
 606   if (size + nmt_header_size > alloc_size) { // Check for rollover.
 607     return NULL;
 608   }
 609 #endif
 610 
 611   // For the test flag -XX:MallocMaxTestWords
 612   if (has_reached_max_malloc_test_peak(size)) {
 613     return NULL;
 614   }
 615 
 616   u_char* ptr;
 617   ptr = (u_char*)::malloc(alloc_size);
 618 
 619 #ifdef ASSERT
 620   if (ptr == NULL) {
 621     return NULL;
 622   }
 623   // Wrap memory with guard
 624   GuardedMemory guarded(ptr, size + nmt_header_size);
 625   ptr = guarded.get_user_ptr();
 626 #endif
 627   if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
 628     tty->print_cr("os::malloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 629     breakpoint();
 630   }
 631   debug_only(if (paranoid) verify_memory(ptr));
 632   if (PrintMalloc && tty != NULL) {
 633     tty->print_cr("os::malloc " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 634   }
 635 
 636   // we do not track guard memory
 637   return MemTracker::record_malloc((address)ptr, size, memflags, stack, level);
 638 }
 639 
 640 void* os::realloc(void *memblock, size_t size, MEMFLAGS flags) {
 641   return os::realloc(memblock, size, flags, CALLER_PC);
 642 }
 643 
 644 void* os::realloc(void *memblock, size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
 645 
 646   // For the test flag -XX:MallocMaxTestWords
 647   if (has_reached_max_malloc_test_peak(size)) {
 648     return NULL;
 649   }
 650 
 651   if (size == 0) {
 652     // return a valid pointer if size is zero
 653     // if NULL is returned the calling functions assume out of memory.
 654     size = 1;
 655   }
 656 
 657 #ifndef ASSERT
 658   NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
 659   NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
 660    // NMT support
 661   void* membase = MemTracker::record_free(memblock);
 662   NMT_TrackingLevel level = MemTracker::tracking_level();
 663   size_t  nmt_header_size = MemTracker::malloc_header_size(level);
 664   void* ptr = ::realloc(membase, size + nmt_header_size);
 665   return MemTracker::record_malloc(ptr, size, memflags, stack, level);
 666 #else
 667   if (memblock == NULL) {
 668     return os::malloc(size, memflags, stack);
 669   }
 670   if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
 671     tty->print_cr("os::realloc caught " PTR_FORMAT, p2i(memblock));
 672     breakpoint();
 673   }
 674   // NMT support
 675   void* membase = MemTracker::malloc_base(memblock);
 676   verify_memory(membase);
 677   // always move the block
 678   void* ptr = os::malloc(size, memflags, stack);
 679   if (PrintMalloc && tty != NULL) {
 680     tty->print_cr("os::realloc " SIZE_FORMAT " bytes, " PTR_FORMAT " --> " PTR_FORMAT, size, p2i(memblock), p2i(ptr));
 681   }
 682   // Copy to new memory if malloc didn't fail
 683   if ( ptr != NULL ) {
 684     GuardedMemory guarded(MemTracker::malloc_base(memblock));
 685     // Guard's user data contains NMT header
 686     size_t memblock_size = guarded.get_user_size() - MemTracker::malloc_header_size(memblock);
 687     memcpy(ptr, memblock, MIN2(size, memblock_size));
 688     if (paranoid) verify_memory(MemTracker::malloc_base(ptr));
 689     if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
 690       tty->print_cr("os::realloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
 691       breakpoint();
 692     }
 693     os::free(memblock);
 694   }
 695   return ptr;
 696 #endif
 697 }
 698 
 699 
 700 void  os::free(void *memblock) {
 701   NOT_PRODUCT(inc_stat_counter(&num_frees, 1));
 702 #ifdef ASSERT
 703   if (memblock == NULL) return;
 704   if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
 705     if (tty != NULL) tty->print_cr("os::free caught " PTR_FORMAT, p2i(memblock));
 706     breakpoint();
 707   }
 708   void* membase = MemTracker::record_free(memblock);
 709   verify_memory(membase);
 710 
 711   GuardedMemory guarded(membase);
 712   size_t size = guarded.get_user_size();
 713   inc_stat_counter(&free_bytes, size);
 714   membase = guarded.release_for_freeing();
 715   if (PrintMalloc && tty != NULL) {
 716       fprintf(stderr, "os::free " SIZE_FORMAT " bytes --> " PTR_FORMAT "\n", size, (uintptr_t)membase);
 717   }
 718   ::free(membase);
 719 #else
 720   void* membase = MemTracker::record_free(memblock);
 721   ::free(membase);
 722 #endif
 723 }
 724 
 725 void os::init_random(long initval) {
 726   _rand_seed = initval;
 727 }
 728 
 729 
 730 long os::random() {
 731   /* standard, well-known linear congruential random generator with
 732    * next_rand = (16807*seed) mod (2**31-1)
 733    * see
 734    * (1) "Random Number Generators: Good Ones Are Hard to Find",
 735    *      S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
 736    * (2) "Two Fast Implementations of the 'Minimal Standard' Random
 737    *     Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
 738   */
 739   const long a = 16807;
 740   const unsigned long m = 2147483647;
 741   const long q = m / a;        assert(q == 127773, "weird math");
 742   const long r = m % a;        assert(r == 2836, "weird math");
 743 
 744   // compute az=2^31p+q
 745   unsigned long lo = a * (long)(_rand_seed & 0xFFFF);
 746   unsigned long hi = a * (long)((unsigned long)_rand_seed >> 16);
 747   lo += (hi & 0x7FFF) << 16;
 748 
 749   // if q overflowed, ignore the overflow and increment q
 750   if (lo > m) {
 751     lo &= m;
 752     ++lo;
 753   }
 754   lo += hi >> 15;
 755 
 756   // if (p+q) overflowed, ignore the overflow and increment (p+q)
 757   if (lo > m) {
 758     lo &= m;
 759     ++lo;
 760   }
 761   return (_rand_seed = lo);
 762 }
 763 
 764 // The INITIALIZED state is distinguished from the SUSPENDED state because the
 765 // conditions in which a thread is first started are different from those in which
 766 // a suspension is resumed.  These differences make it hard for us to apply the
 767 // tougher checks when starting threads that we want to do when resuming them.
 768 // However, when start_thread is called as a result of Thread.start, on a Java
 769 // thread, the operation is synchronized on the Java Thread object.  So there
 770 // cannot be a race to start the thread and hence for the thread to exit while
 771 // we are working on it.  Non-Java threads that start Java threads either have
 772 // to do so in a context in which races are impossible, or should do appropriate
 773 // locking.
 774 
 775 void os::start_thread(Thread* thread) {
 776   // guard suspend/resume
 777   MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
 778   OSThread* osthread = thread->osthread();
 779   osthread->set_state(RUNNABLE);
 780   pd_start_thread(thread);
 781 }
 782 
 783 void os::abort(bool dump_core) {
 784   abort(dump_core && CreateCoredumpOnCrash, NULL, NULL);
 785 }
 786 
 787 //---------------------------------------------------------------------------
 788 // Helper functions for fatal error handler
 789 
 790 void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
 791   assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");
 792 
 793   int cols = 0;
 794   int cols_per_line = 0;
 795   switch (unitsize) {
 796     case 1: cols_per_line = 16; break;
 797     case 2: cols_per_line = 8;  break;
 798     case 4: cols_per_line = 4;  break;
 799     case 8: cols_per_line = 2;  break;
 800     default: return;
 801   }
 802 
 803   address p = start;
 804   st->print(PTR_FORMAT ":   ", p2i(start));
 805   while (p < end) {
 806     switch (unitsize) {
 807       case 1: st->print("%02x", *(u1*)p); break;
 808       case 2: st->print("%04x", *(u2*)p); break;
 809       case 4: st->print("%08x", *(u4*)p); break;
 810       case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
 811     }
 812     p += unitsize;
 813     cols++;
 814     if (cols >= cols_per_line && p < end) {
 815        cols = 0;
 816        st->cr();
 817        st->print(PTR_FORMAT ":   ", p2i(p));
 818     } else {
 819        st->print(" ");
 820     }
 821   }
 822   st->cr();
 823 }
 824 
 825 void os::print_environment_variables(outputStream* st, const char** env_list) {
 826   if (env_list) {
 827     st->print_cr("Environment Variables:");
 828 
 829     for (int i = 0; env_list[i] != NULL; i++) {
 830       char *envvar = ::getenv(env_list[i]);
 831       if (envvar != NULL) {
 832         st->print("%s", env_list[i]);
 833         st->print("=");
 834         st->print_cr("%s", envvar);
 835       }
 836     }
 837   }
 838 }
 839 
 840 void os::print_cpu_info(outputStream* st, char* buf, size_t buflen) {
 841   // cpu
 842   st->print("CPU:");
 843   st->print("total %d", os::processor_count());
 844   // It's not safe to query number of active processors after crash
 845   // st->print("(active %d)", os::active_processor_count()); but we can
 846   // print the initial number of active processors.
 847   // We access the raw value here because the assert in the accessor will
 848   // fail if the crash occurs before initialization of this value.
 849   st->print(" (initial active %d)", _initial_active_processor_count);
 850   st->print(" %s", VM_Version::features_string());
 851   st->cr();
 852   pd_print_cpu_info(st, buf, buflen);
 853 }
 854 
 855 // Print a one line string summarizing the cpu, number of cores, memory, and operating system version
 856 void os::print_summary_info(outputStream* st, char* buf, size_t buflen) {
 857   st->print("Host: ");
 858 #ifndef PRODUCT
 859   if (get_host_name(buf, buflen)) {
 860     st->print("%s, ", buf);
 861   }
 862 #endif // PRODUCT
 863   get_summary_cpu_info(buf, buflen);
 864   st->print("%s, ", buf);
 865   size_t mem = physical_memory()/G;
 866   if (mem == 0) {  // for low memory systems
 867     mem = physical_memory()/M;
 868     st->print("%d cores, " SIZE_FORMAT "M, ", processor_count(), mem);
 869   } else {
 870     st->print("%d cores, " SIZE_FORMAT "G, ", processor_count(), mem);
 871   }
 872   get_summary_os_info(buf, buflen);
 873   st->print_raw(buf);
 874   st->cr();
 875 }
 876 
 877 void os::print_date_and_time(outputStream *st, char* buf, size_t buflen) {
 878   const int secs_per_day  = 86400;
 879   const int secs_per_hour = 3600;
 880   const int secs_per_min  = 60;
 881 
 882   time_t tloc;
 883   (void)time(&tloc);
 884   char* timestring = ctime(&tloc);  // ctime adds newline.
 885   // edit out the newline
 886   char* nl = strchr(timestring, '\n');
 887   if (nl != NULL) {
 888     *nl = '\0';
 889   }
 890 
 891   struct tm tz;
 892   if (localtime_pd(&tloc, &tz) != NULL) {
 893     ::strftime(buf, buflen, "%Z", &tz);
 894     st->print("Time: %s %s", timestring, buf);
 895   } else {
 896     st->print("Time: %s", timestring);
 897   }
 898 
 899   double t = os::elapsedTime();
 900   // NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
 901   //       Linux. Must be a bug in glibc ? Workaround is to round "t" to int
 902   //       before printf. We lost some precision, but who cares?
 903   int eltime = (int)t;  // elapsed time in seconds
 904 
 905   // print elapsed time in a human-readable format:
 906   int eldays = eltime / secs_per_day;
 907   int day_secs = eldays * secs_per_day;
 908   int elhours = (eltime - day_secs) / secs_per_hour;
 909   int hour_secs = elhours * secs_per_hour;
 910   int elmins = (eltime - day_secs - hour_secs) / secs_per_min;
 911   int minute_secs = elmins * secs_per_min;
 912   int elsecs = (eltime - day_secs - hour_secs - minute_secs);
 913   st->print_cr(" elapsed time: %d seconds (%dd %dh %dm %ds)", eltime, eldays, elhours, elmins, elsecs);
 914 }
 915 
 916 // moved from debug.cpp (used to be find()) but still called from there
 917 // The verbose parameter is only set by the debug code in one case
 918 void os::print_location(outputStream* st, intptr_t x, bool verbose) {
 919   address addr = (address)x;
 920   CodeBlob* b = CodeCache::find_blob_unsafe(addr);
 921   if (b != NULL) {
 922     if (b->is_buffer_blob()) {
 923       // the interpreter is generated into a buffer blob
 924       InterpreterCodelet* i = Interpreter::codelet_containing(addr);
 925       if (i != NULL) {
 926         st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an Interpreter codelet", p2i(addr), (int)(addr - i->code_begin()));
 927         i->print_on(st);
 928         return;
 929       }
 930       if (Interpreter::contains(addr)) {
 931         st->print_cr(INTPTR_FORMAT " is pointing into interpreter code"
 932                      " (not bytecode specific)", p2i(addr));
 933         return;
 934       }
 935       //
 936       if (AdapterHandlerLibrary::contains(b)) {
 937         st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an AdapterHandler", p2i(addr), (int)(addr - b->code_begin()));
 938         AdapterHandlerLibrary::print_handler_on(st, b);
 939       }
 940       // the stubroutines are generated into a buffer blob
 941       StubCodeDesc* d = StubCodeDesc::desc_for(addr);
 942       if (d != NULL) {
 943         st->print_cr(INTPTR_FORMAT " is at begin+%d in a stub", p2i(addr), (int)(addr - d->begin()));
 944         d->print_on(st);
 945         st->cr();
 946         return;
 947       }
 948       if (StubRoutines::contains(addr)) {
 949         st->print_cr(INTPTR_FORMAT " is pointing to an (unnamed) stub routine", p2i(addr));
 950         return;
 951       }
 952       // the InlineCacheBuffer is using stubs generated into a buffer blob
 953       if (InlineCacheBuffer::contains(addr)) {
 954         st->print_cr(INTPTR_FORMAT " is pointing into InlineCacheBuffer", p2i(addr));
 955         return;
 956       }
 957       VtableStub* v = VtableStubs::stub_containing(addr);
 958       if (v != NULL) {
 959         st->print_cr(INTPTR_FORMAT " is at entry_point+%d in a vtable stub", p2i(addr), (int)(addr - v->entry_point()));
 960         v->print_on(st);
 961         st->cr();
 962         return;
 963       }
 964     }
 965     nmethod* nm = b->as_nmethod_or_null();
 966     if (nm != NULL) {
 967       ResourceMark rm;
 968       st->print(INTPTR_FORMAT " is at entry_point+%d in (nmethod*)" INTPTR_FORMAT,
 969                 p2i(addr), (int)(addr - nm->entry_point()), p2i(nm));
 970       if (verbose) {
 971         st->print(" for ");
 972         nm->method()->print_value_on(st);
 973       }
 974       st->cr();
 975       nm->print_nmethod(verbose);
 976       return;
 977     }
 978     st->print_cr(INTPTR_FORMAT " is at code_begin+%d in ", p2i(addr), (int)(addr - b->code_begin()));
 979     b->print_on(st);
 980     return;
 981   }
 982 
 983   if (Universe::heap()->is_in(addr)) {
 984     HeapWord* p = Universe::heap()->block_start(addr);
 985     bool print = false;
 986     // If we couldn't find it it just may mean that heap wasn't parsable
 987     // See if we were just given an oop directly
 988     if (p != NULL && Universe::heap()->block_is_obj(p)) {
 989       print = true;
 990     } else if (p == NULL && ((oopDesc*)addr)->is_oop()) {
 991       p = (HeapWord*) addr;
 992       print = true;
 993     }
 994     if (print) {
 995       if (p == (HeapWord*) addr) {
 996         st->print_cr(INTPTR_FORMAT " is an oop", p2i(addr));
 997       } else {
 998         st->print_cr(INTPTR_FORMAT " is pointing into object: " INTPTR_FORMAT, p2i(addr), p2i(p));
 999       }
1000       oop(p)->print_on(st);
1001       return;
1002     }
1003   } else {
1004     if (Universe::heap()->is_in_reserved(addr)) {
1005       st->print_cr(INTPTR_FORMAT " is an unallocated location "
1006                    "in the heap", p2i(addr));
1007       return;
1008     }
1009   }
1010   if (JNIHandles::is_global_handle((jobject) addr)) {
1011     st->print_cr(INTPTR_FORMAT " is a global jni handle", p2i(addr));
1012     return;
1013   }
1014   if (JNIHandles::is_weak_global_handle((jobject) addr)) {
1015     st->print_cr(INTPTR_FORMAT " is a weak global jni handle", p2i(addr));
1016     return;
1017   }
1018 #ifndef PRODUCT
1019   // we don't keep the block list in product mode
1020   if (JNIHandleBlock::any_contains((jobject) addr)) {
1021     st->print_cr(INTPTR_FORMAT " is a local jni handle", p2i(addr));
1022     return;
1023   }
1024 #endif
1025 
1026   for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
1027     // Check for privilege stack
1028     if (thread->privileged_stack_top() != NULL &&
1029         thread->privileged_stack_top()->contains(addr)) {
1030       st->print_cr(INTPTR_FORMAT " is pointing into the privilege stack "
1031                    "for thread: " INTPTR_FORMAT, p2i(addr), p2i(thread));
1032       if (verbose) thread->print_on(st);
1033       return;
1034     }
1035     // If the addr is a java thread print information about that.
1036     if (addr == (address)thread) {
1037       if (verbose) {
1038         thread->print_on(st);
1039       } else {
1040         st->print_cr(INTPTR_FORMAT " is a thread", p2i(addr));
1041       }
1042       return;
1043     }
1044     // If the addr is in the stack region for this thread then report that
1045     // and print thread info
1046     if (thread->on_local_stack(addr)) {
1047       st->print_cr(INTPTR_FORMAT " is pointing into the stack for thread: "
1048                    INTPTR_FORMAT, p2i(addr), p2i(thread));
1049       if (verbose) thread->print_on(st);
1050       return;
1051     }
1052 
1053   }
1054 
1055   // Check if in metaspace and print types that have vptrs (only method now)
1056   if (Metaspace::contains(addr)) {
1057     if (Method::has_method_vptr((const void*)addr)) {
1058       ((Method*)addr)->print_value_on(st);
1059       st->cr();
1060     } else {
1061       // Use addr->print() from the debugger instead (not here)
1062       st->print_cr(INTPTR_FORMAT " is pointing into metadata", p2i(addr));
1063     }
1064     return;
1065   }
1066 
1067   // Try an OS specific find
1068   if (os::find(addr, st)) {
1069     return;
1070   }
1071 
1072   st->print_cr(INTPTR_FORMAT " is an unknown value", p2i(addr));
1073 }
1074 
1075 // Looks like all platforms except IA64 can use the same function to check
1076 // if C stack is walkable beyond current frame. The check for fp() is not
1077 // necessary on Sparc, but it's harmless.
1078 bool os::is_first_C_frame(frame* fr) {
1079 #if (defined(IA64) && !defined(AIX)) && !defined(_WIN32)
1080   // On IA64 we have to check if the callers bsp is still valid
1081   // (i.e. within the register stack bounds).
1082   // Notice: this only works for threads created by the VM and only if
1083   // we walk the current stack!!! If we want to be able to walk
1084   // arbitrary other threads, we'll have to somehow store the thread
1085   // object in the frame.
1086   Thread *thread = Thread::current();
1087   if ((address)fr->fp() <=
1088       thread->register_stack_base() HPUX_ONLY(+ 0x0) LINUX_ONLY(+ 0x50)) {
1089     // This check is a little hacky, because on Linux the first C
1090     // frame's ('start_thread') register stack frame starts at
1091     // "register_stack_base + 0x48" while on HPUX, the first C frame's
1092     // ('__pthread_bound_body') register stack frame seems to really
1093     // start at "register_stack_base".
1094     return true;
1095   } else {
1096     return false;
1097   }
1098 #elif defined(IA64) && defined(_WIN32)
1099   return true;
1100 #else
1101   // Load up sp, fp, sender sp and sender fp, check for reasonable values.
1102   // Check usp first, because if that's bad the other accessors may fault
1103   // on some architectures.  Ditto ufp second, etc.
1104   uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
1105   // sp on amd can be 32 bit aligned.
1106   uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);
1107 
1108   uintptr_t usp    = (uintptr_t)fr->sp();
1109   if ((usp & sp_align_mask) != 0) return true;
1110 
1111   uintptr_t ufp    = (uintptr_t)fr->fp();
1112   if ((ufp & fp_align_mask) != 0) return true;
1113 
1114   uintptr_t old_sp = (uintptr_t)fr->sender_sp();
1115   if ((old_sp & sp_align_mask) != 0) return true;
1116   if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;
1117 
1118   uintptr_t old_fp = (uintptr_t)fr->link();
1119   if ((old_fp & fp_align_mask) != 0) return true;
1120   if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;
1121 
1122   // stack grows downwards; if old_fp is below current fp or if the stack
1123   // frame is too large, either the stack is corrupted or fp is not saved
1124   // on stack (i.e. on x86, ebp may be used as general register). The stack
1125   // is not walkable beyond current frame.
1126   if (old_fp < ufp) return true;
1127   if (old_fp - ufp > 64 * K) return true;
1128 
1129   return false;
1130 #endif
1131 }
1132 
1133 #ifdef ASSERT
1134 extern "C" void test_random() {
1135   const double m = 2147483647;
1136   double mean = 0.0, variance = 0.0, t;
1137   long reps = 10000;
1138   unsigned long seed = 1;
1139 
1140   tty->print_cr("seed %ld for %ld repeats...", seed, reps);
1141   os::init_random(seed);
1142   long num;
1143   for (int k = 0; k < reps; k++) {
1144     num = os::random();
1145     double u = (double)num / m;
1146     assert(u >= 0.0 && u <= 1.0, "bad random number!");
1147 
1148     // calculate mean and variance of the random sequence
1149     mean += u;
1150     variance += (u*u);
1151   }
1152   mean /= reps;
1153   variance /= (reps - 1);
1154 
1155   assert(num == 1043618065, "bad seed");
1156   tty->print_cr("mean of the 1st 10000 numbers: %f", mean);
1157   tty->print_cr("variance of the 1st 10000 numbers: %f", variance);
1158   const double eps = 0.0001;
1159   t = fabsd(mean - 0.5018);
1160   assert(t < eps, "bad mean");
1161   t = (variance - 0.3355) < 0.0 ? -(variance - 0.3355) : variance - 0.3355;
1162   assert(t < eps, "bad variance");
1163 }
1164 #endif
1165 
1166 
1167 // Set up the boot classpath.
1168 
1169 char* os::format_boot_path(const char* format_string,
1170                            const char* home,
1171                            int home_len,
1172                            char fileSep,
1173                            char pathSep) {
1174     assert((fileSep == '/' && pathSep == ':') ||
1175            (fileSep == '\\' && pathSep == ';'), "unexpected separator chars");
1176 
1177     // Scan the format string to determine the length of the actual
1178     // boot classpath, and handle platform dependencies as well.
1179     int formatted_path_len = 0;
1180     const char* p;
1181     for (p = format_string; *p != 0; ++p) {
1182         if (*p == '%') formatted_path_len += home_len - 1;
1183         ++formatted_path_len;
1184     }
1185 
1186     char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1, mtInternal);
1187     if (formatted_path == NULL) {
1188         return NULL;
1189     }
1190 
1191     // Create boot classpath from format, substituting separator chars and
1192     // java home directory.
1193     char* q = formatted_path;
1194     for (p = format_string; *p != 0; ++p) {
1195         switch (*p) {
1196         case '%':
1197             strcpy(q, home);
1198             q += home_len;
1199             break;
1200         case '/':
1201             *q++ = fileSep;
1202             break;
1203         case ':':
1204             *q++ = pathSep;
1205             break;
1206         default:
1207             *q++ = *p;
1208         }
1209     }
1210     *q = '\0';
1211 
1212     assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
1213     return formatted_path;
1214 }
1215 
1216 bool os::set_boot_path(char fileSep, char pathSep) {
1217   const char* home = Arguments::get_java_home();
1218   int home_len = (int)strlen(home);
1219 
1220   struct stat st;
1221 
1222   // modular image if "modules" jimage exists
1223   char* jimage = format_boot_path("%/lib/" MODULES_IMAGE_NAME, home, home_len, fileSep, pathSep);
1224   if (jimage == NULL) return false;
1225   bool has_jimage = (os::stat(jimage, &st) == 0);
1226   if (has_jimage) {
1227     Arguments::set_sysclasspath(jimage, true);
1228     FREE_C_HEAP_ARRAY(char, jimage);
1229     return true;
1230   }
1231   FREE_C_HEAP_ARRAY(char, jimage);
1232 
1233   // check if developer build with exploded modules
1234   char* base_classes = format_boot_path("%/modules/" JAVA_BASE_NAME, home, home_len, fileSep, pathSep);
1235   if (base_classes == NULL) return false;
1236   if (os::stat(base_classes, &st) == 0) {
1237     Arguments::set_sysclasspath(base_classes, false);
1238     FREE_C_HEAP_ARRAY(char, base_classes);
1239     return true;
1240   }
1241   FREE_C_HEAP_ARRAY(char, base_classes);
1242 
1243   return false;
1244 }
1245 
1246 /*
1247  * Splits a path, based on its separator, the number of
1248  * elements is returned back in n.
1249  * It is the callers responsibility to:
1250  *   a> check the value of n, and n may be 0.
1251  *   b> ignore any empty path elements
1252  *   c> free up the data.
1253  */
1254 char** os::split_path(const char* path, int* n) {
1255   *n = 0;
1256   if (path == NULL || strlen(path) == 0) {
1257     return NULL;
1258   }
1259   const char psepchar = *os::path_separator();
1260   char* inpath = (char*)NEW_C_HEAP_ARRAY(char, strlen(path) + 1, mtInternal);
1261   if (inpath == NULL) {
1262     return NULL;
1263   }
1264   strcpy(inpath, path);
1265   int count = 1;
1266   char* p = strchr(inpath, psepchar);
1267   // Get a count of elements to allocate memory
1268   while (p != NULL) {
1269     count++;
1270     p++;
1271     p = strchr(p, psepchar);
1272   }
1273   char** opath = (char**) NEW_C_HEAP_ARRAY(char*, count, mtInternal);
1274   if (opath == NULL) {
1275     return NULL;
1276   }
1277 
1278   // do the actual splitting
1279   p = inpath;
1280   for (int i = 0 ; i < count ; i++) {
1281     size_t len = strcspn(p, os::path_separator());
1282     if (len > JVM_MAXPATHLEN) {
1283       return NULL;
1284     }
1285     // allocate the string and add terminator storage
1286     char* s  = (char*)NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
1287     if (s == NULL) {
1288       return NULL;
1289     }
1290     strncpy(s, p, len);
1291     s[len] = '\0';
1292     opath[i] = s;
1293     p += len + 1;
1294   }
1295   FREE_C_HEAP_ARRAY(char, inpath);
1296   *n = count;
1297   return opath;
1298 }
1299 
1300 void os::set_memory_serialize_page(address page) {
1301   int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
1302   _mem_serialize_page = (volatile int32_t *)page;
1303   // We initialize the serialization page shift count here
1304   // We assume a cache line size of 64 bytes
1305   assert(SerializePageShiftCount == count, "JavaThread size changed; "
1306          "SerializePageShiftCount constant should be %d", count);
1307   set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
1308 }
1309 
1310 static volatile intptr_t SerializePageLock = 0;
1311 
1312 // This method is called from signal handler when SIGSEGV occurs while the current
1313 // thread tries to store to the "read-only" memory serialize page during state
1314 // transition.
1315 void os::block_on_serialize_page_trap() {
1316   log_debug(safepoint)("Block until the serialize page permission restored");
1317 
1318   // When VMThread is holding the SerializePageLock during modifying the
1319   // access permission of the memory serialize page, the following call
1320   // will block until the permission of that page is restored to rw.
1321   // Generally, it is unsafe to manipulate locks in signal handlers, but in
1322   // this case, it's OK as the signal is synchronous and we know precisely when
1323   // it can occur.
1324   Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
1325   Thread::muxRelease(&SerializePageLock);
1326 }
1327 
1328 // Serialize all thread state variables
1329 void os::serialize_thread_states() {
1330   // On some platforms such as Solaris & Linux, the time duration of the page
1331   // permission restoration is observed to be much longer than expected  due to
1332   // scheduler starvation problem etc. To avoid the long synchronization
1333   // time and expensive page trap spinning, 'SerializePageLock' is used to block
1334   // the mutator thread if such case is encountered. See bug 6546278 for details.
1335   Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
1336   os::protect_memory((char *)os::get_memory_serialize_page(),
1337                      os::vm_page_size(), MEM_PROT_READ);
1338   os::protect_memory((char *)os::get_memory_serialize_page(),
1339                      os::vm_page_size(), MEM_PROT_RW);
1340   Thread::muxRelease(&SerializePageLock);
1341 }
1342 
1343 // Returns true if the current stack pointer is above the stack shadow
1344 // pages, false otherwise.
1345 bool os::stack_shadow_pages_available(Thread *thread, const methodHandle& method, address sp) {
1346   if (!thread->is_Java_thread()) return false;
1347   // Check if we have StackShadowPages above the yellow zone.  This parameter
1348   // is dependent on the depth of the maximum VM call stack possible from
1349   // the handler for stack overflow.  'instanceof' in the stack overflow
1350   // handler or a println uses at least 8k stack of VM and native code
1351   // respectively.
1352   const int framesize_in_bytes =
1353     Interpreter::size_top_interpreter_activation(method()) * wordSize;
1354 
1355   address limit = ((JavaThread*)thread)->stack_end() +
1356                   (JavaThread::stack_guard_zone_size() + JavaThread::stack_shadow_zone_size());
1357 
1358   return sp > (limit + framesize_in_bytes);
1359 }
1360 
1361 size_t os::page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned) {
1362   assert(min_pages > 0, "sanity");
1363   if (UseLargePages) {
1364     const size_t max_page_size = region_size / min_pages;
1365 
1366     for (size_t i = 0; _page_sizes[i] != 0; ++i) {
1367       const size_t page_size = _page_sizes[i];
1368       if (page_size <= max_page_size) {
1369         if (!must_be_aligned || is_aligned(region_size, page_size)) {
1370           return page_size;
1371         }
1372       }
1373     }
1374   }
1375 
1376   return vm_page_size();
1377 }
1378 
1379 size_t os::page_size_for_region_aligned(size_t region_size, size_t min_pages) {
1380   return page_size_for_region(region_size, min_pages, true);
1381 }
1382 
1383 size_t os::page_size_for_region_unaligned(size_t region_size, size_t min_pages) {
1384   return page_size_for_region(region_size, min_pages, false);
1385 }
1386 
1387 static const char* errno_to_string (int e, bool short_text) {
1388   #define ALL_SHARED_ENUMS(X) \
1389     X(E2BIG, "Argument list too long") \
1390     X(EACCES, "Permission denied") \
1391     X(EADDRINUSE, "Address in use") \
1392     X(EADDRNOTAVAIL, "Address not available") \
1393     X(EAFNOSUPPORT, "Address family not supported") \
1394     X(EAGAIN, "Resource unavailable, try again") \
1395     X(EALREADY, "Connection already in progress") \
1396     X(EBADF, "Bad file descriptor") \
1397     X(EBADMSG, "Bad message") \
1398     X(EBUSY, "Device or resource busy") \
1399     X(ECANCELED, "Operation canceled") \
1400     X(ECHILD, "No child processes") \
1401     X(ECONNABORTED, "Connection aborted") \
1402     X(ECONNREFUSED, "Connection refused") \
1403     X(ECONNRESET, "Connection reset") \
1404     X(EDEADLK, "Resource deadlock would occur") \
1405     X(EDESTADDRREQ, "Destination address required") \
1406     X(EDOM, "Mathematics argument out of domain of function") \
1407     X(EEXIST, "File exists") \
1408     X(EFAULT, "Bad address") \
1409     X(EFBIG, "File too large") \
1410     X(EHOSTUNREACH, "Host is unreachable") \
1411     X(EIDRM, "Identifier removed") \
1412     X(EILSEQ, "Illegal byte sequence") \
1413     X(EINPROGRESS, "Operation in progress") \
1414     X(EINTR, "Interrupted function") \
1415     X(EINVAL, "Invalid argument") \
1416     X(EIO, "I/O error") \
1417     X(EISCONN, "Socket is connected") \
1418     X(EISDIR, "Is a directory") \
1419     X(ELOOP, "Too many levels of symbolic links") \
1420     X(EMFILE, "Too many open files") \
1421     X(EMLINK, "Too many links") \
1422     X(EMSGSIZE, "Message too large") \
1423     X(ENAMETOOLONG, "Filename too long") \
1424     X(ENETDOWN, "Network is down") \
1425     X(ENETRESET, "Connection aborted by network") \
1426     X(ENETUNREACH, "Network unreachable") \
1427     X(ENFILE, "Too many files open in system") \
1428     X(ENOBUFS, "No buffer space available") \
1429     X(ENODATA, "No message is available on the STREAM head read queue") \
1430     X(ENODEV, "No such device") \
1431     X(ENOENT, "No such file or directory") \
1432     X(ENOEXEC, "Executable file format error") \
1433     X(ENOLCK, "No locks available") \
1434     X(ENOLINK, "Reserved") \
1435     X(ENOMEM, "Not enough space") \
1436     X(ENOMSG, "No message of the desired type") \
1437     X(ENOPROTOOPT, "Protocol not available") \
1438     X(ENOSPC, "No space left on device") \
1439     X(ENOSR, "No STREAM resources") \
1440     X(ENOSTR, "Not a STREAM") \
1441     X(ENOSYS, "Function not supported") \
1442     X(ENOTCONN, "The socket is not connected") \
1443     X(ENOTDIR, "Not a directory") \
1444     X(ENOTEMPTY, "Directory not empty") \
1445     X(ENOTSOCK, "Not a socket") \
1446     X(ENOTSUP, "Not supported") \
1447     X(ENOTTY, "Inappropriate I/O control operation") \
1448     X(ENXIO, "No such device or address") \
1449     X(EOPNOTSUPP, "Operation not supported on socket") \
1450     X(EOVERFLOW, "Value too large to be stored in data type") \
1451     X(EPERM, "Operation not permitted") \
1452     X(EPIPE, "Broken pipe") \
1453     X(EPROTO, "Protocol error") \
1454     X(EPROTONOSUPPORT, "Protocol not supported") \
1455     X(EPROTOTYPE, "Protocol wrong type for socket") \
1456     X(ERANGE, "Result too large") \
1457     X(EROFS, "Read-only file system") \
1458     X(ESPIPE, "Invalid seek") \
1459     X(ESRCH, "No such process") \
1460     X(ETIME, "Stream ioctl() timeout") \
1461     X(ETIMEDOUT, "Connection timed out") \
1462     X(ETXTBSY, "Text file busy") \
1463     X(EWOULDBLOCK, "Operation would block") \
1464     X(EXDEV, "Cross-device link")
1465 
1466   #define DEFINE_ENTRY(e, text) { e, #e, text },
1467 
1468   static const struct {
1469     int v;
1470     const char* short_text;
1471     const char* long_text;
1472   } table [] = {
1473 
1474     ALL_SHARED_ENUMS(DEFINE_ENTRY)
1475 
1476     // The following enums are not defined on all platforms.
1477     #ifdef ESTALE
1478     DEFINE_ENTRY(ESTALE, "Reserved")
1479     #endif
1480     #ifdef EDQUOT
1481     DEFINE_ENTRY(EDQUOT, "Reserved")
1482     #endif
1483     #ifdef EMULTIHOP
1484     DEFINE_ENTRY(EMULTIHOP, "Reserved")
1485     #endif
1486 
1487     // End marker.
1488     { -1, "Unknown errno", "Unknown error" }
1489 
1490   };
1491 
1492   #undef DEFINE_ENTRY
1493   #undef ALL_FLAGS
1494 
1495   int i = 0;
1496   while (table[i].v != -1 && table[i].v != e) {
1497     i ++;
1498   }
1499 
1500   return short_text ? table[i].short_text : table[i].long_text;
1501 
1502 }
1503 
1504 const char* os::strerror(int e) {
1505   return errno_to_string(e, false);
1506 }
1507 
1508 const char* os::errno_name(int e) {
1509   return errno_to_string(e, true);
1510 }
1511 
1512 void os::trace_page_sizes(const char* str, const size_t* page_sizes, int count) {
1513   LogTarget(Info, pagesize) log;
1514   if (log.is_enabled()) {
1515     LogStreamCHeap out(log);
1516 
1517     out.print("%s: ", str);
1518     for (int i = 0; i < count; ++i) {
1519       out.print(" " SIZE_FORMAT, page_sizes[i]);
1520     }
1521     out.cr();
1522   }
1523 }
1524 
1525 #define trace_page_size_params(size) byte_size_in_exact_unit(size), exact_unit_for_byte_size(size)
1526 
1527 void os::trace_page_sizes(const char* str,
1528                           const size_t region_min_size,
1529                           const size_t region_max_size,
1530                           const size_t page_size,
1531                           const char* base,
1532                           const size_t size) {
1533 
1534   log_info(pagesize)("%s: "
1535                      " min=" SIZE_FORMAT "%s"
1536                      " max=" SIZE_FORMAT "%s"
1537                      " base=" PTR_FORMAT
1538                      " page_size=" SIZE_FORMAT "%s"
1539                      " size=" SIZE_FORMAT "%s",
1540                      str,
1541                      trace_page_size_params(region_min_size),
1542                      trace_page_size_params(region_max_size),
1543                      p2i(base),
1544                      trace_page_size_params(page_size),
1545                      trace_page_size_params(size));
1546 }
1547 
1548 void os::trace_page_sizes_for_requested_size(const char* str,
1549                                              const size_t requested_size,
1550                                              const size_t page_size,
1551                                              const size_t alignment,
1552                                              const char* base,
1553                                              const size_t size) {
1554 
1555   log_info(pagesize)("%s:"
1556                      " req_size=" SIZE_FORMAT "%s"
1557                      " base=" PTR_FORMAT
1558                      " page_size=" SIZE_FORMAT "%s"
1559                      " alignment=" SIZE_FORMAT "%s"
1560                      " size=" SIZE_FORMAT "%s",
1561                      str,
1562                      trace_page_size_params(requested_size),
1563                      p2i(base),
1564                      trace_page_size_params(page_size),
1565                      trace_page_size_params(alignment),
1566                      trace_page_size_params(size));
1567 }
1568 
1569 
1570 // This is the working definition of a server class machine:
1571 // >= 2 physical CPU's and >=2GB of memory, with some fuzz
1572 // because the graphics memory (?) sometimes masks physical memory.
1573 // If you want to change the definition of a server class machine
1574 // on some OS or platform, e.g., >=4GB on Windows platforms,
1575 // then you'll have to parameterize this method based on that state,
1576 // as was done for logical processors here, or replicate and
1577 // specialize this method for each platform.  (Or fix os to have
1578 // some inheritance structure and use subclassing.  Sigh.)
1579 // If you want some platform to always or never behave as a server
1580 // class machine, change the setting of AlwaysActAsServerClassMachine
1581 // and NeverActAsServerClassMachine in globals*.hpp.
1582 bool os::is_server_class_machine() {
1583   // First check for the early returns
1584   if (NeverActAsServerClassMachine) {
1585     return false;
1586   }
1587   if (AlwaysActAsServerClassMachine) {
1588     return true;
1589   }
1590   // Then actually look at the machine
1591   bool         result            = false;
1592   const unsigned int    server_processors = 2;
1593   const julong server_memory     = 2UL * G;
1594   // We seem not to get our full complement of memory.
1595   //     We allow some part (1/8?) of the memory to be "missing",
1596   //     based on the sizes of DIMMs, and maybe graphics cards.
1597   const julong missing_memory   = 256UL * M;
1598 
1599   /* Is this a server class machine? */
1600   if ((os::active_processor_count() >= (int)server_processors) &&
1601       (os::physical_memory() >= (server_memory - missing_memory))) {
1602     const unsigned int logical_processors =
1603       VM_Version::logical_processors_per_package();
1604     if (logical_processors > 1) {
1605       const unsigned int physical_packages =
1606         os::active_processor_count() / logical_processors;
1607       if (physical_packages >= server_processors) {
1608         result = true;
1609       }
1610     } else {
1611       result = true;
1612     }
1613   }
1614   return result;
1615 }
1616 
1617 void os::initialize_initial_active_processor_count() {
1618   assert(_initial_active_processor_count == 0, "Initial active processor count already set.");
1619   _initial_active_processor_count = active_processor_count();
1620   log_debug(os)("Initial active processor count set to %d" , _initial_active_processor_count);
1621 }
1622 
1623 void os::SuspendedThreadTask::run() {
1624   assert(Threads_lock->owned_by_self() || (_thread == VMThread::vm_thread()), "must have threads lock to call this");
1625   internal_do_task();
1626   _done = true;
1627 }
1628 
1629 bool os::create_stack_guard_pages(char* addr, size_t bytes) {
1630   return os::pd_create_stack_guard_pages(addr, bytes);
1631 }
1632 
1633 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint) {
1634   char* result = pd_reserve_memory(bytes, addr, alignment_hint);
1635   if (result != NULL) {
1636     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1637   }
1638 
1639   return result;
1640 }
1641 
1642 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint,
1643    MEMFLAGS flags) {
1644   char* result = pd_reserve_memory(bytes, addr, alignment_hint);
1645   if (result != NULL) {
1646     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1647     MemTracker::record_virtual_memory_type((address)result, flags);
1648   }
1649 
1650   return result;
1651 }
1652 
1653 char* os::attempt_reserve_memory_at(size_t bytes, char* addr) {
1654   char* result = pd_attempt_reserve_memory_at(bytes, addr);
1655   if (result != NULL) {
1656     MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1657   }
1658   return result;
1659 }
1660 
1661 void os::split_reserved_memory(char *base, size_t size,
1662                                  size_t split, bool realloc) {
1663   pd_split_reserved_memory(base, size, split, realloc);
1664 }
1665 
1666 bool os::commit_memory(char* addr, size_t bytes, bool executable) {
1667   bool res = pd_commit_memory(addr, bytes, executable);
1668   if (res) {
1669     MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1670   }
1671   return res;
1672 }
1673 
1674 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint,
1675                               bool executable) {
1676   bool res = os::pd_commit_memory(addr, size, alignment_hint, executable);
1677   if (res) {
1678     MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1679   }
1680   return res;
1681 }
1682 
1683 void os::commit_memory_or_exit(char* addr, size_t bytes, bool executable,
1684                                const char* mesg) {
1685   pd_commit_memory_or_exit(addr, bytes, executable, mesg);
1686   MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1687 }
1688 
1689 void os::commit_memory_or_exit(char* addr, size_t size, size_t alignment_hint,
1690                                bool executable, const char* mesg) {
1691   os::pd_commit_memory_or_exit(addr, size, alignment_hint, executable, mesg);
1692   MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1693 }
1694 
1695 bool os::uncommit_memory(char* addr, size_t bytes) {
1696   bool res;
1697   if (MemTracker::tracking_level() > NMT_minimal) {
1698     Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
1699     res = pd_uncommit_memory(addr, bytes);
1700     if (res) {
1701       tkr.record((address)addr, bytes);
1702     }
1703   } else {
1704     res = pd_uncommit_memory(addr, bytes);
1705   }
1706   return res;
1707 }
1708 
1709 bool os::release_memory(char* addr, size_t bytes) {
1710   bool res;
1711   if (MemTracker::tracking_level() > NMT_minimal) {
1712     Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
1713     res = pd_release_memory(addr, bytes);
1714     if (res) {
1715       tkr.record((address)addr, bytes);
1716     }
1717   } else {
1718     res = pd_release_memory(addr, bytes);
1719   }
1720   return res;
1721 }
1722 
1723 void os::pretouch_memory(void* start, void* end, size_t page_size) {
1724   for (volatile char *p = (char*)start; p < (char*)end; p += page_size) {
1725     *p = 0;
1726   }
1727 }
1728 
1729 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
1730                            char *addr, size_t bytes, bool read_only,
1731                            bool allow_exec) {
1732   char* result = pd_map_memory(fd, file_name, file_offset, addr, bytes, read_only, allow_exec);
1733   if (result != NULL) {
1734     MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
1735   }
1736   return result;
1737 }
1738 
1739 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
1740                              char *addr, size_t bytes, bool read_only,
1741                              bool allow_exec) {
1742   return pd_remap_memory(fd, file_name, file_offset, addr, bytes,
1743                     read_only, allow_exec);
1744 }
1745 
1746 bool os::unmap_memory(char *addr, size_t bytes) {
1747   bool result;
1748   if (MemTracker::tracking_level() > NMT_minimal) {
1749     Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
1750     result = pd_unmap_memory(addr, bytes);
1751     if (result) {
1752       tkr.record((address)addr, bytes);
1753     }
1754   } else {
1755     result = pd_unmap_memory(addr, bytes);
1756   }
1757   return result;
1758 }
1759 
1760 void os::free_memory(char *addr, size_t bytes, size_t alignment_hint) {
1761   pd_free_memory(addr, bytes, alignment_hint);
1762 }
1763 
1764 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
1765   pd_realign_memory(addr, bytes, alignment_hint);
1766 }
1767 
1768 #ifndef _WINDOWS
1769 /* try to switch state from state "from" to state "to"
1770  * returns the state set after the method is complete
1771  */
1772 os::SuspendResume::State os::SuspendResume::switch_state(os::SuspendResume::State from,
1773                                                          os::SuspendResume::State to)
1774 {
1775   os::SuspendResume::State result =
1776     (os::SuspendResume::State) Atomic::cmpxchg((jint) to, (jint *) &_state, (jint) from);
1777   if (result == from) {
1778     // success
1779     return to;
1780   }
1781   return result;
1782 }
1783 #endif