view src/share/vm/runtime/os.cpp @ 8746:7f39700be72a

8026324: hs_err improvement: Add summary section to hs_err file 8026333: hs_err improvement: Print GC Strategy 8026336: hs_err improvement: Print compilation mode, server, client or tiered Summary: Added command line, summary cpu and os information to summary section. Moved time of crash and duration in summary section. Add GC strategy and compiler setting (tiered) to enhanced version string in error report. Moved the stack trace sooner in hs_err file. Reviewed-by: dholmes, ctornqvi, ddmitriev
author coleenp
date Wed, 22 Jul 2015 00:03:45 -0400
parents 60f7aacc348d
children 2c352a332507
line wrap: on
line source
/*
 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/codeCache.hpp"
#include "code/icBuffer.hpp"
#include "code/vtableStubs.hpp"
#include "gc/shared/vmGCOperations.hpp"
#include "interpreter/interpreter.hpp"
#include "memory/allocation.inline.hpp"
#ifdef ASSERT
#include "memory/guardedMemory.hpp"
#endif
#include "oops/oop.inline.hpp"
#include "prims/jvm.h"
#include "prims/jvm_misc.hpp"
#include "prims/privilegedStack.hpp"
#include "runtime/arguments.hpp"
#include "runtime/atomic.inline.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/os.inline.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/vm_version.hpp"
#include "services/attachListener.hpp"
#include "services/mallocTracker.hpp"
#include "services/memTracker.hpp"
#include "services/nmtCommon.hpp"
#include "services/threadService.hpp"
#include "utilities/defaultStream.hpp"
#include "utilities/events.hpp"

# include <signal.h>

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

OSThread*         os::_starting_thread    = NULL;
address           os::_polling_page       = NULL;
volatile int32_t* os::_mem_serialize_page = NULL;
uintptr_t         os::_serialize_page_mask = 0;
long              os::_rand_seed          = 1;
int               os::_processor_count    = 0;
size_t            os::_page_sizes[os::page_sizes_max];

#ifndef PRODUCT
julong os::num_mallocs = 0;         // # of calls to malloc/realloc
julong os::alloc_bytes = 0;         // # of bytes allocated
julong os::num_frees = 0;           // # of calls to free
julong os::free_bytes = 0;          // # of bytes freed
#endif

static juint cur_malloc_words = 0;  // current size for MallocMaxTestWords

void os_init_globals() {
  // Called from init_globals().
  // See Threads::create_vm() in thread.cpp, and init.cpp.
  os::init_globals();
}

// Fill in buffer with current local time as an ISO-8601 string.
// E.g., yyyy-mm-ddThh:mm:ss-zzzz.
// Returns buffer, or NULL if it failed.
// This would mostly be a call to
//     strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
// except that on Windows the %z behaves badly, so we do it ourselves.
// Also, people wanted milliseconds on there,
// and strftime doesn't do milliseconds.
char* os::iso8601_time(char* buffer, size_t buffer_length) {
  // Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
  //                                      1         2
  //                             12345678901234567890123456789
  static const char* iso8601_format =
    "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d";
  static const size_t needed_buffer = 29;

  // Sanity check the arguments
  if (buffer == NULL) {
    assert(false, "NULL buffer");
    return NULL;
  }
  if (buffer_length < needed_buffer) {
    assert(false, "buffer_length too small");
    return NULL;
  }
  // Get the current time
  jlong milliseconds_since_19700101 = javaTimeMillis();
  const int milliseconds_per_microsecond = 1000;
  const time_t seconds_since_19700101 =
    milliseconds_since_19700101 / milliseconds_per_microsecond;
  const int milliseconds_after_second =
    milliseconds_since_19700101 % milliseconds_per_microsecond;
  // Convert the time value to a tm and timezone variable
  struct tm time_struct;
  if (localtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
    assert(false, "Failed localtime_pd");
    return NULL;
  }
#if defined(_ALLBSD_SOURCE)
  const time_t zone = (time_t) time_struct.tm_gmtoff;
#else
  const time_t zone = timezone;
#endif

  // If daylight savings time is in effect,
  // we are 1 hour East of our time zone
  const time_t seconds_per_minute = 60;
  const time_t minutes_per_hour = 60;
  const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
  time_t UTC_to_local = zone;
  if (time_struct.tm_isdst > 0) {
    UTC_to_local = UTC_to_local - seconds_per_hour;
  }
  // Compute the time zone offset.
  //    localtime_pd() sets timezone to the difference (in seconds)
  //    between UTC and and local time.
  //    ISO 8601 says we need the difference between local time and UTC,
  //    we change the sign of the localtime_pd() result.
  const time_t local_to_UTC = -(UTC_to_local);
  // Then we have to figure out if if we are ahead (+) or behind (-) UTC.
  char sign_local_to_UTC = '+';
  time_t abs_local_to_UTC = local_to_UTC;
  if (local_to_UTC < 0) {
    sign_local_to_UTC = '-';
    abs_local_to_UTC = -(abs_local_to_UTC);
  }
  // Convert time zone offset seconds to hours and minutes.
  const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
  const time_t zone_min =
    ((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);

  // Print an ISO 8601 date and time stamp into the buffer
  const int year = 1900 + time_struct.tm_year;
  const int month = 1 + time_struct.tm_mon;
  const int printed = jio_snprintf(buffer, buffer_length, iso8601_format,
                                   year,
                                   month,
                                   time_struct.tm_mday,
                                   time_struct.tm_hour,
                                   time_struct.tm_min,
                                   time_struct.tm_sec,
                                   milliseconds_after_second,
                                   sign_local_to_UTC,
                                   zone_hours,
                                   zone_min);
  if (printed == 0) {
    assert(false, "Failed jio_printf");
    return NULL;
  }
  return buffer;
}

OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
#ifdef ASSERT
  if (!(!thread->is_Java_thread() ||
         Thread::current() == thread  ||
         Threads_lock->owned_by_self()
         || thread->is_Compiler_thread()
        )) {
    assert(false, "possibility of dangling Thread pointer");
  }
#endif

  if (p >= MinPriority && p <= MaxPriority) {
    int priority = java_to_os_priority[p];
    return set_native_priority(thread, priority);
  } else {
    assert(false, "Should not happen");
    return OS_ERR;
  }
}

// The mapping from OS priority back to Java priority may be inexact because
// Java priorities can map M:1 with native priorities. If you want the definite
// Java priority then use JavaThread::java_priority()
OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
  int p;
  int os_prio;
  OSReturn ret = get_native_priority(thread, &os_prio);
  if (ret != OS_OK) return ret;

  if (java_to_os_priority[MaxPriority] > java_to_os_priority[MinPriority]) {
    for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
  } else {
    // niceness values are in reverse order
    for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] < os_prio; p--) ;
  }
  priority = (ThreadPriority)p;
  return OS_OK;
}


// --------------------- sun.misc.Signal (optional) ---------------------


// SIGBREAK is sent by the keyboard to query the VM state
#ifndef SIGBREAK
#define SIGBREAK SIGQUIT
#endif

// sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.


static void signal_thread_entry(JavaThread* thread, TRAPS) {
  os::set_priority(thread, NearMaxPriority);
  while (true) {
    int sig;
    {
      // FIXME : Currently we have not decided what should be the status
      //         for this java thread blocked here. Once we decide about
      //         that we should fix this.
      sig = os::signal_wait();
    }
    if (sig == os::sigexitnum_pd()) {
       // Terminate the signal thread
       return;
    }

    switch (sig) {
      case SIGBREAK: {
        // Check if the signal is a trigger to start the Attach Listener - in that
        // case don't print stack traces.
        if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
          continue;
        }
        // Print stack traces
        // Any SIGBREAK operations added here should make sure to flush
        // the output stream (e.g. tty->flush()) after output.  See 4803766.
        // Each module also prints an extra carriage return after its output.
        VM_PrintThreads op;
        VMThread::execute(&op);
        VM_PrintJNI jni_op;
        VMThread::execute(&jni_op);
        VM_FindDeadlocks op1(tty);
        VMThread::execute(&op1);
        Universe::print_heap_at_SIGBREAK();
        if (PrintClassHistogram) {
          VM_GC_HeapInspection op1(gclog_or_tty, true /* force full GC before heap inspection */);
          VMThread::execute(&op1);
        }
        if (JvmtiExport::should_post_data_dump()) {
          JvmtiExport::post_data_dump();
        }
        break;
      }
      default: {
        // Dispatch the signal to java
        HandleMark hm(THREAD);
        Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_Signal(), THREAD);
        KlassHandle klass (THREAD, k);
        if (klass.not_null()) {
          JavaValue result(T_VOID);
          JavaCallArguments args;
          args.push_int(sig);
          JavaCalls::call_static(
            &result,
            klass,
            vmSymbols::dispatch_name(),
            vmSymbols::int_void_signature(),
            &args,
            THREAD
          );
        }
        if (HAS_PENDING_EXCEPTION) {
          // tty is initialized early so we don't expect it to be null, but
          // if it is we can't risk doing an initialization that might
          // trigger additional out-of-memory conditions
          if (tty != NULL) {
            char klass_name[256];
            char tmp_sig_name[16];
            const char* sig_name = "UNKNOWN";
            InstanceKlass::cast(PENDING_EXCEPTION->klass())->
              name()->as_klass_external_name(klass_name, 256);
            if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
              sig_name = tmp_sig_name;
            warning("Exception %s occurred dispatching signal %s to handler"
                    "- the VM may need to be forcibly terminated",
                    klass_name, sig_name );
          }
          CLEAR_PENDING_EXCEPTION;
        }
      }
    }
  }
}

void os::init_before_ergo() {
  // We need to initialize large page support here because ergonomics takes some
  // decisions depending on large page support and the calculated large page size.
  large_page_init();
}

void os::signal_init() {
  if (!ReduceSignalUsage) {
    // Setup JavaThread for processing signals
    EXCEPTION_MARK;
    Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
    instanceKlassHandle klass (THREAD, k);
    instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);

    const char thread_name[] = "Signal Dispatcher";
    Handle string = java_lang_String::create_from_str(thread_name, CHECK);

    // Initialize thread_oop to put it into the system threadGroup
    Handle thread_group (THREAD, Universe::system_thread_group());
    JavaValue result(T_VOID);
    JavaCalls::call_special(&result, thread_oop,
                           klass,
                           vmSymbols::object_initializer_name(),
                           vmSymbols::threadgroup_string_void_signature(),
                           thread_group,
                           string,
                           CHECK);

    KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
    JavaCalls::call_special(&result,
                            thread_group,
                            group,
                            vmSymbols::add_method_name(),
                            vmSymbols::thread_void_signature(),
                            thread_oop,         // ARG 1
                            CHECK);

    os::signal_init_pd();

    { MutexLocker mu(Threads_lock);
      JavaThread* signal_thread = new JavaThread(&signal_thread_entry);

      // At this point it may be possible that no osthread was created for the
      // JavaThread due to lack of memory. We would have to throw an exception
      // in that case. However, since this must work and we do not allow
      // exceptions anyway, check and abort if this fails.
      if (signal_thread == NULL || signal_thread->osthread() == NULL) {
        vm_exit_during_initialization("java.lang.OutOfMemoryError",
                                      os::native_thread_creation_failed_msg());
      }

      java_lang_Thread::set_thread(thread_oop(), signal_thread);
      java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
      java_lang_Thread::set_daemon(thread_oop());

      signal_thread->set_threadObj(thread_oop());
      Threads::add(signal_thread);
      Thread::start(signal_thread);
    }
    // Handle ^BREAK
    os::signal(SIGBREAK, os::user_handler());
  }
}


void os::terminate_signal_thread() {
  if (!ReduceSignalUsage)
    signal_notify(sigexitnum_pd());
}


// --------------------- loading libraries ---------------------

typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
extern struct JavaVM_ main_vm;

static void* _native_java_library = NULL;

void* os::native_java_library() {
  if (_native_java_library == NULL) {
    char buffer[JVM_MAXPATHLEN];
    char ebuf[1024];

    // Try to load verify dll first. In 1.3 java dll depends on it and is not
    // always able to find it when the loading executable is outside the JDK.
    // In order to keep working with 1.2 we ignore any loading errors.
    if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
                       "verify")) {
      dll_load(buffer, ebuf, sizeof(ebuf));
    }

    // Load java dll
    if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
                       "java")) {
      _native_java_library = dll_load(buffer, ebuf, sizeof(ebuf));
    }
    if (_native_java_library == NULL) {
      vm_exit_during_initialization("Unable to load native library", ebuf);
    }

#if defined(__OpenBSD__)
    // Work-around OpenBSD's lack of $ORIGIN support by pre-loading libnet.so
    // ignore errors
    if (dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
                       "net")) {
      dll_load(buffer, ebuf, sizeof(ebuf));
    }
#endif
  }
  static jboolean onLoaded = JNI_FALSE;
  if (onLoaded) {
    // We may have to wait to fire OnLoad until TLS is initialized.
    if (ThreadLocalStorage::is_initialized()) {
      // The JNI_OnLoad handling is normally done by method load in
      // java.lang.ClassLoader$NativeLibrary, but the VM loads the base library
      // explicitly so we have to check for JNI_OnLoad as well
      const char *onLoadSymbols[] = JNI_ONLOAD_SYMBOLS;
      JNI_OnLoad_t JNI_OnLoad = CAST_TO_FN_PTR(
          JNI_OnLoad_t, dll_lookup(_native_java_library, onLoadSymbols[0]));
      if (JNI_OnLoad != NULL) {
        JavaThread* thread = JavaThread::current();
        ThreadToNativeFromVM ttn(thread);
        HandleMark hm(thread);
        jint ver = (*JNI_OnLoad)(&main_vm, NULL);
        onLoaded = JNI_TRUE;
        if (!Threads::is_supported_jni_version_including_1_1(ver)) {
          vm_exit_during_initialization("Unsupported JNI version");
        }
      }
    }
  }
  return _native_java_library;
}

/*
 * Support for finding Agent_On(Un)Load/Attach<_lib_name> if it exists.
 * If check_lib == true then we are looking for an
 * Agent_OnLoad_lib_name or Agent_OnAttach_lib_name function to determine if
 * this library is statically linked into the image.
 * If check_lib == false then we will look for the appropriate symbol in the
 * executable if agent_lib->is_static_lib() == true or in the shared library
 * referenced by 'handle'.
 */
void* os::find_agent_function(AgentLibrary *agent_lib, bool check_lib,
                              const char *syms[], size_t syms_len) {
  assert(agent_lib != NULL, "sanity check");
  const char *lib_name;
  void *handle = agent_lib->os_lib();
  void *entryName = NULL;
  char *agent_function_name;
  size_t i;

  // If checking then use the agent name otherwise test is_static_lib() to
  // see how to process this lookup
  lib_name = ((check_lib || agent_lib->is_static_lib()) ? agent_lib->name() : NULL);
  for (i = 0; i < syms_len; i++) {
    agent_function_name = build_agent_function_name(syms[i], lib_name, agent_lib->is_absolute_path());
    if (agent_function_name == NULL) {
      break;
    }
    entryName = dll_lookup(handle, agent_function_name);
    FREE_C_HEAP_ARRAY(char, agent_function_name);
    if (entryName != NULL) {
      break;
    }
  }
  return entryName;
}

// See if the passed in agent is statically linked into the VM image.
bool os::find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
                            size_t syms_len) {
  void *ret;
  void *proc_handle;
  void *save_handle;

  assert(agent_lib != NULL, "sanity check");
  if (agent_lib->name() == NULL) {
    return false;
  }
  proc_handle = get_default_process_handle();
  // Check for Agent_OnLoad/Attach_lib_name function
  save_handle = agent_lib->os_lib();
  // We want to look in this process' symbol table.
  agent_lib->set_os_lib(proc_handle);
  ret = find_agent_function(agent_lib, true, syms, syms_len);
  if (ret != NULL) {
    // Found an entry point like Agent_OnLoad_lib_name so we have a static agent
    agent_lib->set_valid();
    agent_lib->set_static_lib(true);
    return true;
  }
  agent_lib->set_os_lib(save_handle);
  return false;
}

// --------------------- heap allocation utilities ---------------------

char *os::strdup(const char *str, MEMFLAGS flags) {
  size_t size = strlen(str);
  char *dup_str = (char *)malloc(size + 1, flags);
  if (dup_str == NULL) return NULL;
  strcpy(dup_str, str);
  return dup_str;
}

char* os::strdup_check_oom(const char* str, MEMFLAGS flags) {
  char* p = os::strdup(str, flags);
  if (p == NULL) {
    vm_exit_out_of_memory(strlen(str) + 1, OOM_MALLOC_ERROR, "os::strdup_check_oom");
  }
  return p;
}


#define paranoid                 0  /* only set to 1 if you suspect checking code has bug */

#ifdef ASSERT

static void verify_memory(void* ptr) {
  GuardedMemory guarded(ptr);
  if (!guarded.verify_guards()) {
    tty->print_cr("## nof_mallocs = " UINT64_FORMAT ", nof_frees = " UINT64_FORMAT, os::num_mallocs, os::num_frees);
    tty->print_cr("## memory stomp:");
    guarded.print_on(tty);
    fatal("memory stomping error");
  }
}

#endif

//
// This function supports testing of the malloc out of memory
// condition without really running the system out of memory.
//
static bool has_reached_max_malloc_test_peak(size_t alloc_size) {
  if (MallocMaxTestWords > 0) {
    jint words = (jint)(alloc_size / BytesPerWord);

    if ((cur_malloc_words + words) > MallocMaxTestWords) {
      return true;
    }
    Atomic::add(words, (volatile jint *)&cur_malloc_words);
  }
  return false;
}

void* os::malloc(size_t size, MEMFLAGS flags) {
  return os::malloc(size, flags, CALLER_PC);
}

void* os::malloc(size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
  NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
  NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));

#ifdef ASSERT
  // checking for the WatcherThread and crash_protection first
  // since os::malloc can be called when the libjvm.{dll,so} is
  // first loaded and we don't have a thread yet.
  // try to find the thread after we see that the watcher thread
  // exists and has crash protection.
  WatcherThread *wt = WatcherThread::watcher_thread();
  if (wt != NULL && wt->has_crash_protection()) {
    Thread* thread = ThreadLocalStorage::get_thread_slow();
    if (thread == wt) {
      assert(!wt->has_crash_protection(),
          "Can't malloc with crash protection from WatcherThread");
    }
  }
#endif

  if (size == 0) {
    // return a valid pointer if size is zero
    // if NULL is returned the calling functions assume out of memory.
    size = 1;
  }

  // NMT support
  NMT_TrackingLevel level = MemTracker::tracking_level();
  size_t            nmt_header_size = MemTracker::malloc_header_size(level);

#ifndef ASSERT
  const size_t alloc_size = size + nmt_header_size;
#else
  const size_t alloc_size = GuardedMemory::get_total_size(size + nmt_header_size);
  if (size + nmt_header_size > alloc_size) { // Check for rollover.
    return NULL;
  }
#endif

  NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());

  // For the test flag -XX:MallocMaxTestWords
  if (has_reached_max_malloc_test_peak(size)) {
    return NULL;
  }

  u_char* ptr;
  ptr = (u_char*)::malloc(alloc_size);

#ifdef ASSERT
  if (ptr == NULL) {
    return NULL;
  }
  // Wrap memory with guard
  GuardedMemory guarded(ptr, size + nmt_header_size);
  ptr = guarded.get_user_ptr();
#endif
  if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
    tty->print_cr("os::malloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, ptr);
    breakpoint();
  }
  debug_only(if (paranoid) verify_memory(ptr));
  if (PrintMalloc && tty != NULL) {
    tty->print_cr("os::malloc " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, ptr);
  }

  // we do not track guard memory
  return MemTracker::record_malloc((address)ptr, size, memflags, stack, level);
}

void* os::realloc(void *memblock, size_t size, MEMFLAGS flags) {
  return os::realloc(memblock, size, flags, CALLER_PC);
}

void* os::realloc(void *memblock, size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {

  // For the test flag -XX:MallocMaxTestWords
  if (has_reached_max_malloc_test_peak(size)) {
    return NULL;
  }

#ifndef ASSERT
  NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
  NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
   // NMT support
  void* membase = MemTracker::record_free(memblock);
  NMT_TrackingLevel level = MemTracker::tracking_level();
  size_t  nmt_header_size = MemTracker::malloc_header_size(level);
  void* ptr = ::realloc(membase, size + nmt_header_size);
  return MemTracker::record_malloc(ptr, size, memflags, stack, level);
#else
  if (memblock == NULL) {
    return os::malloc(size, memflags, stack);
  }
  if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
    tty->print_cr("os::realloc caught " PTR_FORMAT, memblock);
    breakpoint();
  }
  // NMT support
  void* membase = MemTracker::malloc_base(memblock);
  verify_memory(membase);
  NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
  if (size == 0) {
    return NULL;
  }
  // always move the block
  void* ptr = os::malloc(size, memflags, stack);
  if (PrintMalloc && tty != NULL) {
    tty->print_cr("os::realloc " SIZE_FORMAT " bytes, " PTR_FORMAT " --> " PTR_FORMAT, size, memblock, ptr);
  }
  // Copy to new memory if malloc didn't fail
  if ( ptr != NULL ) {
    GuardedMemory guarded(MemTracker::malloc_base(memblock));
    // Guard's user data contains NMT header
    size_t memblock_size = guarded.get_user_size() - MemTracker::malloc_header_size(memblock);
    memcpy(ptr, memblock, MIN2(size, memblock_size));
    if (paranoid) verify_memory(MemTracker::malloc_base(ptr));
    if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
      tty->print_cr("os::realloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, ptr);
      breakpoint();
    }
    os::free(memblock);
  }
  return ptr;
#endif
}


void  os::free(void *memblock) {
  NOT_PRODUCT(inc_stat_counter(&num_frees, 1));
#ifdef ASSERT
  if (memblock == NULL) return;
  if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
    if (tty != NULL) tty->print_cr("os::free caught " PTR_FORMAT, memblock);
    breakpoint();
  }
  void* membase = MemTracker::record_free(memblock);
  verify_memory(membase);
  NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());

  GuardedMemory guarded(membase);
  size_t size = guarded.get_user_size();
  inc_stat_counter(&free_bytes, size);
  membase = guarded.release_for_freeing();
  if (PrintMalloc && tty != NULL) {
      fprintf(stderr, "os::free " SIZE_FORMAT " bytes --> " PTR_FORMAT "\n", size, (uintptr_t)membase);
  }
  ::free(membase);
#else
  void* membase = MemTracker::record_free(memblock);
  ::free(membase);
#endif
}

void os::init_random(long initval) {
  _rand_seed = initval;
}


long os::random() {
  /* standard, well-known linear congruential random generator with
   * next_rand = (16807*seed) mod (2**31-1)
   * see
   * (1) "Random Number Generators: Good Ones Are Hard to Find",
   *      S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
   * (2) "Two Fast Implementations of the 'Minimal Standard' Random
   *     Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
  */
  const long a = 16807;
  const unsigned long m = 2147483647;
  const long q = m / a;        assert(q == 127773, "weird math");
  const long r = m % a;        assert(r == 2836, "weird math");

  // compute az=2^31p+q
  unsigned long lo = a * (long)(_rand_seed & 0xFFFF);
  unsigned long hi = a * (long)((unsigned long)_rand_seed >> 16);
  lo += (hi & 0x7FFF) << 16;

  // if q overflowed, ignore the overflow and increment q
  if (lo > m) {
    lo &= m;
    ++lo;
  }
  lo += hi >> 15;

  // if (p+q) overflowed, ignore the overflow and increment (p+q)
  if (lo > m) {
    lo &= m;
    ++lo;
  }
  return (_rand_seed = lo);
}

// The INITIALIZED state is distinguished from the SUSPENDED state because the
// conditions in which a thread is first started are different from those in which
// a suspension is resumed.  These differences make it hard for us to apply the
// tougher checks when starting threads that we want to do when resuming them.
// However, when start_thread is called as a result of Thread.start, on a Java
// thread, the operation is synchronized on the Java Thread object.  So there
// cannot be a race to start the thread and hence for the thread to exit while
// we are working on it.  Non-Java threads that start Java threads either have
// to do so in a context in which races are impossible, or should do appropriate
// locking.

void os::start_thread(Thread* thread) {
  // guard suspend/resume
  MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
  OSThread* osthread = thread->osthread();
  osthread->set_state(RUNNABLE);
  pd_start_thread(thread);
}

void os::abort(bool dump_core) {
  abort(dump_core && CreateCoredumpOnCrash, NULL, NULL);
}

//---------------------------------------------------------------------------
// Helper functions for fatal error handler

void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
  assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");

  int cols = 0;
  int cols_per_line = 0;
  switch (unitsize) {
    case 1: cols_per_line = 16; break;
    case 2: cols_per_line = 8;  break;
    case 4: cols_per_line = 4;  break;
    case 8: cols_per_line = 2;  break;
    default: return;
  }

  address p = start;
  st->print(PTR_FORMAT ":   ", start);
  while (p < end) {
    switch (unitsize) {
      case 1: st->print("%02x", *(u1*)p); break;
      case 2: st->print("%04x", *(u2*)p); break;
      case 4: st->print("%08x", *(u4*)p); break;
      case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
    }
    p += unitsize;
    cols++;
    if (cols >= cols_per_line && p < end) {
       cols = 0;
       st->cr();
       st->print(PTR_FORMAT ":   ", p);
    } else {
       st->print(" ");
    }
  }
  st->cr();
}

void os::print_environment_variables(outputStream* st, const char** env_list) {
  if (env_list) {
    st->print_cr("Environment Variables:");

    for (int i = 0; env_list[i] != NULL; i++) {
      char *envvar = ::getenv(env_list[i]);
      if (envvar != NULL) {
        st->print("%s", env_list[i]);
        st->print("=");
        st->print_cr("%s", envvar);
      }
    }
  }
}

void os::print_cpu_info(outputStream* st, char* buf, size_t buflen) {
  // cpu
  st->print("CPU:");
  st->print("total %d", os::processor_count());
  // It's not safe to query number of active processors after crash
  // st->print("(active %d)", os::active_processor_count());
  st->print(" %s", VM_Version::cpu_features());
  st->cr();
  pd_print_cpu_info(st, buf, buflen);
}

// Print a one line string summarizing the cpu, number of cores, memory, and operating system version
void os::print_summary_info(outputStream* st, char* buf, size_t buflen) {
  st->print("Host: ");
#ifndef PRODUCT
  if (get_host_name(buf, buflen)) {
    st->print("%s, ", buf);
  }
#endif // PRODUCT
  get_summary_cpu_info(buf, buflen);
  st->print("%s, ", buf);
  size_t mem = physical_memory()/G;
  if (mem == 0) {  // for low memory systems
    mem = physical_memory()/M;
    st->print("%d cores, %dM, ", processor_count(), mem);
  } else {
    st->print("%d cores, %dG, ", processor_count(), mem);
  }
  get_summary_os_info(buf, buflen);
  st->print_raw(buf);
  st->cr();
}

void os::print_date_and_time(outputStream *st, char* buf, size_t buflen) {
  const int secs_per_day  = 86400;
  const int secs_per_hour = 3600;
  const int secs_per_min  = 60;

  time_t tloc;
  (void)time(&tloc);
  char* timestring = ctime(&tloc);  // ctime adds newline.
  // edit out the newline
  char* nl = strchr(timestring, '\n');
  if (nl != NULL) {
    *nl = '\0';
  }

  struct tm tz;
  if (localtime_pd(&tloc, &tz) != NULL) {
    ::strftime(buf, buflen, "%Z", &tz);
    st->print("Time: %s %s", timestring, buf);
  } else {
    st->print("Time: %s", timestring);
  }

  double t = os::elapsedTime();
  // NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
  //       Linux. Must be a bug in glibc ? Workaround is to round "t" to int
  //       before printf. We lost some precision, but who cares?
  int eltime = (int)t;  // elapsed time in seconds

  // print elapsed time in a human-readable format:
  int eldays = eltime / secs_per_day;
  int day_secs = eldays * secs_per_day;
  int elhours = (eltime - day_secs) / secs_per_hour;
  int hour_secs = elhours * secs_per_hour;
  int elmins = (eltime - day_secs - hour_secs) / secs_per_min;
  int minute_secs = elmins * secs_per_min;
  int elsecs = (eltime - day_secs - hour_secs - minute_secs);
  st->print_cr(" elapsed time: %d seconds (%dd %dh %dm %ds)", eltime, eldays, elhours, elmins, elsecs);
}

// moved from debug.cpp (used to be find()) but still called from there
// The verbose parameter is only set by the debug code in one case
void os::print_location(outputStream* st, intptr_t x, bool verbose) {
  address addr = (address)x;
  CodeBlob* b = CodeCache::find_blob_unsafe(addr);
  if (b != NULL) {
    if (b->is_buffer_blob()) {
      // the interpreter is generated into a buffer blob
      InterpreterCodelet* i = Interpreter::codelet_containing(addr);
      if (i != NULL) {
        st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an Interpreter codelet", addr, (int)(addr - i->code_begin()));
        i->print_on(st);
        return;
      }
      if (Interpreter::contains(addr)) {
        st->print_cr(INTPTR_FORMAT " is pointing into interpreter code"
                     " (not bytecode specific)", addr);
        return;
      }
      //
      if (AdapterHandlerLibrary::contains(b)) {
        st->print_cr(INTPTR_FORMAT " is at code_begin+%d in an AdapterHandler", addr, (int)(addr - b->code_begin()));
        AdapterHandlerLibrary::print_handler_on(st, b);
      }
      // the stubroutines are generated into a buffer blob
      StubCodeDesc* d = StubCodeDesc::desc_for(addr);
      if (d != NULL) {
        st->print_cr(INTPTR_FORMAT " is at begin+%d in a stub", addr, (int)(addr - d->begin()));
        d->print_on(st);
        st->cr();
        return;
      }
      if (StubRoutines::contains(addr)) {
        st->print_cr(INTPTR_FORMAT " is pointing to an (unnamed) "
                     "stub routine", addr);
        return;
      }
      // the InlineCacheBuffer is using stubs generated into a buffer blob
      if (InlineCacheBuffer::contains(addr)) {
        st->print_cr(INTPTR_FORMAT " is pointing into InlineCacheBuffer", addr);
        return;
      }
      VtableStub* v = VtableStubs::stub_containing(addr);
      if (v != NULL) {
        st->print_cr(INTPTR_FORMAT " is at entry_point+%d in a vtable stub", addr, (int)(addr - v->entry_point()));
        v->print_on(st);
        st->cr();
        return;
      }
    }
    nmethod* nm = b->as_nmethod_or_null();
    if (nm != NULL) {
      ResourceMark rm;
      st->print(INTPTR_FORMAT " is at entry_point+%d in (nmethod*)" INTPTR_FORMAT,
                addr, (int)(addr - nm->entry_point()), nm);
      if (verbose) {
        st->print(" for ");
        nm->method()->print_value_on(st);
      }
      st->cr();
      nm->print_nmethod(verbose);
      return;
    }
    st->print_cr(INTPTR_FORMAT " is at code_begin+%d in ", addr, (int)(addr - b->code_begin()));
    b->print_on(st);
    return;
  }

  if (Universe::heap()->is_in(addr)) {
    HeapWord* p = Universe::heap()->block_start(addr);
    bool print = false;
    // If we couldn't find it it just may mean that heap wasn't parsable
    // See if we were just given an oop directly
    if (p != NULL && Universe::heap()->block_is_obj(p)) {
      print = true;
    } else if (p == NULL && ((oopDesc*)addr)->is_oop()) {
      p = (HeapWord*) addr;
      print = true;
    }
    if (print) {
      if (p == (HeapWord*) addr) {
        st->print_cr(INTPTR_FORMAT " is an oop", addr);
      } else {
        st->print_cr(INTPTR_FORMAT " is pointing into object: " INTPTR_FORMAT, addr, p);
      }
      oop(p)->print_on(st);
      return;
    }
  } else {
    if (Universe::heap()->is_in_reserved(addr)) {
      st->print_cr(INTPTR_FORMAT " is an unallocated location "
                   "in the heap", addr);
      return;
    }
  }
  if (JNIHandles::is_global_handle((jobject) addr)) {
    st->print_cr(INTPTR_FORMAT " is a global jni handle", addr);
    return;
  }
  if (JNIHandles::is_weak_global_handle((jobject) addr)) {
    st->print_cr(INTPTR_FORMAT " is a weak global jni handle", addr);
    return;
  }
#ifndef PRODUCT
  // we don't keep the block list in product mode
  if (JNIHandleBlock::any_contains((jobject) addr)) {
    st->print_cr(INTPTR_FORMAT " is a local jni handle", addr);
    return;
  }
#endif

  for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
    // Check for privilege stack
    if (thread->privileged_stack_top() != NULL &&
        thread->privileged_stack_top()->contains(addr)) {
      st->print_cr(INTPTR_FORMAT " is pointing into the privilege stack "
                   "for thread: " INTPTR_FORMAT, addr, thread);
      if (verbose) thread->print_on(st);
      return;
    }
    // If the addr is a java thread print information about that.
    if (addr == (address)thread) {
      if (verbose) {
        thread->print_on(st);
      } else {
        st->print_cr(INTPTR_FORMAT " is a thread", addr);
      }
      return;
    }
    // If the addr is in the stack region for this thread then report that
    // and print thread info
    if (thread->stack_base() >= addr &&
        addr > (thread->stack_base() - thread->stack_size())) {
      st->print_cr(INTPTR_FORMAT " is pointing into the stack for thread: "
                   INTPTR_FORMAT, addr, thread);
      if (verbose) thread->print_on(st);
      return;
    }

  }

  // Check if in metaspace and print types that have vptrs (only method now)
  if (Metaspace::contains(addr)) {
    if (Method::has_method_vptr((const void*)addr)) {
      ((Method*)addr)->print_value_on(st);
      st->cr();
    } else {
      // Use addr->print() from the debugger instead (not here)
      st->print_cr(INTPTR_FORMAT " is pointing into metadata", addr);
    }
    return;
  }

  // Try an OS specific find
  if (os::find(addr, st)) {
    return;
  }

  st->print_cr(INTPTR_FORMAT " is an unknown value", addr);
}

// Looks like all platforms except IA64 can use the same function to check
// if C stack is walkable beyond current frame. The check for fp() is not
// necessary on Sparc, but it's harmless.
bool os::is_first_C_frame(frame* fr) {
#if (defined(IA64) && !defined(AIX)) && !defined(_WIN32)
  // On IA64 we have to check if the callers bsp is still valid
  // (i.e. within the register stack bounds).
  // Notice: this only works for threads created by the VM and only if
  // we walk the current stack!!! If we want to be able to walk
  // arbitrary other threads, we'll have to somehow store the thread
  // object in the frame.
  Thread *thread = Thread::current();
  if ((address)fr->fp() <=
      thread->register_stack_base() HPUX_ONLY(+ 0x0) LINUX_ONLY(+ 0x50)) {
    // This check is a little hacky, because on Linux the first C
    // frame's ('start_thread') register stack frame starts at
    // "register_stack_base + 0x48" while on HPUX, the first C frame's
    // ('__pthread_bound_body') register stack frame seems to really
    // start at "register_stack_base".
    return true;
  } else {
    return false;
  }
#elif defined(IA64) && defined(_WIN32)
  return true;
#else
  // Load up sp, fp, sender sp and sender fp, check for reasonable values.
  // Check usp first, because if that's bad the other accessors may fault
  // on some architectures.  Ditto ufp second, etc.
  uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
  // sp on amd can be 32 bit aligned.
  uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);

  uintptr_t usp    = (uintptr_t)fr->sp();
  if ((usp & sp_align_mask) != 0) return true;

  uintptr_t ufp    = (uintptr_t)fr->fp();
  if ((ufp & fp_align_mask) != 0) return true;

  uintptr_t old_sp = (uintptr_t)fr->sender_sp();
  if ((old_sp & sp_align_mask) != 0) return true;
  if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;

  uintptr_t old_fp = (uintptr_t)fr->link();
  if ((old_fp & fp_align_mask) != 0) return true;
  if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;

  // stack grows downwards; if old_fp is below current fp or if the stack
  // frame is too large, either the stack is corrupted or fp is not saved
  // on stack (i.e. on x86, ebp may be used as general register). The stack
  // is not walkable beyond current frame.
  if (old_fp < ufp) return true;
  if (old_fp - ufp > 64 * K) return true;

  return false;
#endif
}

#ifdef ASSERT
extern "C" void test_random() {
  const double m = 2147483647;
  double mean = 0.0, variance = 0.0, t;
  long reps = 10000;
  unsigned long seed = 1;

  tty->print_cr("seed %ld for %ld repeats...", seed, reps);
  os::init_random(seed);
  long num;
  for (int k = 0; k < reps; k++) {
    num = os::random();
    double u = (double)num / m;
    assert(u >= 0.0 && u <= 1.0, "bad random number!");

    // calculate mean and variance of the random sequence
    mean += u;
    variance += (u*u);
  }
  mean /= reps;
  variance /= (reps - 1);

  assert(num == 1043618065, "bad seed");
  tty->print_cr("mean of the 1st 10000 numbers: %f", mean);
  tty->print_cr("variance of the 1st 10000 numbers: %f", variance);
  const double eps = 0.0001;
  t = fabsd(mean - 0.5018);
  assert(t < eps, "bad mean");
  t = (variance - 0.3355) < 0.0 ? -(variance - 0.3355) : variance - 0.3355;
  assert(t < eps, "bad variance");
}
#endif


// Set up the boot classpath.

char* os::format_boot_path(const char* format_string,
                           const char* home,
                           int home_len,
                           char fileSep,
                           char pathSep) {
    assert((fileSep == '/' && pathSep == ':') ||
           (fileSep == '\\' && pathSep == ';'), "unexpected separator chars");

    // Scan the format string to determine the length of the actual
    // boot classpath, and handle platform dependencies as well.
    int formatted_path_len = 0;
    const char* p;
    for (p = format_string; *p != 0; ++p) {
        if (*p == '%') formatted_path_len += home_len - 1;
        ++formatted_path_len;
    }

    char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1, mtInternal);
    if (formatted_path == NULL) {
        return NULL;
    }

    // Create boot classpath from format, substituting separator chars and
    // java home directory.
    char* q = formatted_path;
    for (p = format_string; *p != 0; ++p) {
        switch (*p) {
        case '%':
            strcpy(q, home);
            q += home_len;
            break;
        case '/':
            *q++ = fileSep;
            break;
        case ':':
            *q++ = pathSep;
            break;
        default:
            *q++ = *p;
        }
    }
    *q = '\0';

    assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
    return formatted_path;
}

// returns a PATH of all entries in the given directory that do not start with a '.'
static char* expand_entries_to_path(char* directory, char fileSep, char pathSep) {
  DIR* dir = os::opendir(directory);
  if (dir == NULL) return NULL;

  char* path = NULL;
  size_t path_len = 0;  // path length including \0 terminator

  size_t directory_len = strlen(directory);
  struct dirent *entry;
  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(directory), mtInternal);
  while ((entry = os::readdir(dir, (dirent *) dbuf)) != NULL) {
    const char* name = entry->d_name;
    if (name[0] == '.') continue;

    size_t name_len = strlen(name);
    size_t needed = directory_len + name_len + 2;
    size_t new_len = path_len + needed;
    if (path == NULL) {
      path = NEW_C_HEAP_ARRAY(char, new_len, mtInternal);
    } else {
      path = REALLOC_C_HEAP_ARRAY(char, path, new_len, mtInternal);
    }
    if (path == NULL)
      break;

    // append <pathSep>directory<fileSep>name
    char* p = path;
    if (path_len > 0) {
      p += (path_len -1);
      *p = pathSep;
      p++;
    }

    strcpy(p, directory);
    p += directory_len;

    *p = fileSep;
    p++;

    strcpy(p, name);
    p += name_len;

    path_len = new_len;
  }

  FREE_C_HEAP_ARRAY(char, dbuf);
  os::closedir(dir);

  return path;
}

bool os::set_boot_path(char fileSep, char pathSep) {
  const char* home = Arguments::get_java_home();
  int home_len = (int)strlen(home);

  char* sysclasspath = NULL;
  struct stat st;

  // modular image if bootmodules.jimage exists
  char* jimage = format_boot_path("%/lib/modules/" BOOT_IMAGE_NAME, home, home_len, fileSep, pathSep);
  if (jimage == NULL) return false;
  bool has_jimage = (os::stat(jimage, &st) == 0);
  if (has_jimage) {
    Arguments::set_sysclasspath(jimage);
    return true;
  }
  FREE_C_HEAP_ARRAY(char, jimage);

  // check if developer build with exploded modules
  char* modules_dir = format_boot_path("%/modules", home, home_len, fileSep, pathSep);
  if (os::stat(modules_dir, &st) == 0) {
    if ((st.st_mode & S_IFDIR) == S_IFDIR) {
      sysclasspath = expand_entries_to_path(modules_dir, fileSep, pathSep);
    }
  }

  // fallback to classes
  if (sysclasspath == NULL)
    sysclasspath = format_boot_path("%/classes", home, home_len, fileSep, pathSep);

  if (sysclasspath == NULL) return false;
  Arguments::set_sysclasspath(sysclasspath);

  return true;
}

/*
 * Splits a path, based on its separator, the number of
 * elements is returned back in n.
 * It is the callers responsibility to:
 *   a> check the value of n, and n may be 0.
 *   b> ignore any empty path elements
 *   c> free up the data.
 */
char** os::split_path(const char* path, int* n) {
  *n = 0;
  if (path == NULL || strlen(path) == 0) {
    return NULL;
  }
  const char psepchar = *os::path_separator();
  char* inpath = (char*)NEW_C_HEAP_ARRAY(char, strlen(path) + 1, mtInternal);
  if (inpath == NULL) {
    return NULL;
  }
  strcpy(inpath, path);
  int count = 1;
  char* p = strchr(inpath, psepchar);
  // Get a count of elements to allocate memory
  while (p != NULL) {
    count++;
    p++;
    p = strchr(p, psepchar);
  }
  char** opath = (char**) NEW_C_HEAP_ARRAY(char*, count, mtInternal);
  if (opath == NULL) {
    return NULL;
  }

  // do the actual splitting
  p = inpath;
  for (int i = 0 ; i < count ; i++) {
    size_t len = strcspn(p, os::path_separator());
    if (len > JVM_MAXPATHLEN) {
      return NULL;
    }
    // allocate the string and add terminator storage
    char* s  = (char*)NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
    if (s == NULL) {
      return NULL;
    }
    strncpy(s, p, len);
    s[len] = '\0';
    opath[i] = s;
    p += len + 1;
  }
  FREE_C_HEAP_ARRAY(char, inpath);
  *n = count;
  return opath;
}

void os::set_memory_serialize_page(address page) {
  int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
  _mem_serialize_page = (volatile int32_t *)page;
  // We initialize the serialization page shift count here
  // We assume a cache line size of 64 bytes
  assert(SerializePageShiftCount == count,
         "thread size changed, fix SerializePageShiftCount constant");
  set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
}

static volatile intptr_t SerializePageLock = 0;

// This method is called from signal handler when SIGSEGV occurs while the current
// thread tries to store to the "read-only" memory serialize page during state
// transition.
void os::block_on_serialize_page_trap() {
  if (TraceSafepoint) {
    tty->print_cr("Block until the serialize page permission restored");
  }
  // When VMThread is holding the SerializePageLock during modifying the
  // access permission of the memory serialize page, the following call
  // will block until the permission of that page is restored to rw.
  // Generally, it is unsafe to manipulate locks in signal handlers, but in
  // this case, it's OK as the signal is synchronous and we know precisely when
  // it can occur.
  Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
  Thread::muxRelease(&SerializePageLock);
}

// Serialize all thread state variables
void os::serialize_thread_states() {
  // On some platforms such as Solaris & Linux, the time duration of the page
  // permission restoration is observed to be much longer than expected  due to
  // scheduler starvation problem etc. To avoid the long synchronization
  // time and expensive page trap spinning, 'SerializePageLock' is used to block
  // the mutator thread if such case is encountered. See bug 6546278 for details.
  Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
  os::protect_memory((char *)os::get_memory_serialize_page(),
                     os::vm_page_size(), MEM_PROT_READ);
  os::protect_memory((char *)os::get_memory_serialize_page(),
                     os::vm_page_size(), MEM_PROT_RW);
  Thread::muxRelease(&SerializePageLock);
}

// Returns true if the current stack pointer is above the stack shadow
// pages, false otherwise.

bool os::stack_shadow_pages_available(Thread *thread, methodHandle method) {
  assert(StackRedPages > 0 && StackYellowPages > 0,"Sanity check");
  address sp = current_stack_pointer();
  // Check if we have StackShadowPages above the yellow zone.  This parameter
  // is dependent on the depth of the maximum VM call stack possible from
  // the handler for stack overflow.  'instanceof' in the stack overflow
  // handler or a println uses at least 8k stack of VM and native code
  // respectively.
  const int framesize_in_bytes =
    Interpreter::size_top_interpreter_activation(method()) * wordSize;
  int reserved_area = ((StackShadowPages + StackRedPages + StackYellowPages)
                      * vm_page_size()) + framesize_in_bytes;
  // The very lower end of the stack
  address stack_limit = thread->stack_base() - thread->stack_size();
  return (sp > (stack_limit + reserved_area));
}

size_t os::page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned) {
  assert(min_pages > 0, "sanity");
  if (UseLargePages) {
    const size_t max_page_size = region_size / min_pages;

    for (size_t i = 0; _page_sizes[i] != 0; ++i) {
      const size_t page_size = _page_sizes[i];
      if (page_size <= max_page_size) {
        if (!must_be_aligned || is_size_aligned(region_size, page_size)) {
          return page_size;
        }
      }
    }
  }

  return vm_page_size();
}

size_t os::page_size_for_region_aligned(size_t region_size, size_t min_pages) {
  return page_size_for_region(region_size, min_pages, true);
}

size_t os::page_size_for_region_unaligned(size_t region_size, size_t min_pages) {
  return page_size_for_region(region_size, min_pages, false);
}

#ifndef PRODUCT
void os::trace_page_sizes(const char* str, const size_t* page_sizes, int count)
{
  if (TracePageSizes) {
    tty->print("%s: ", str);
    for (int i = 0; i < count; ++i) {
      tty->print(" " SIZE_FORMAT, page_sizes[i]);
    }
    tty->cr();
  }
}

void os::trace_page_sizes(const char* str, const size_t region_min_size,
                          const size_t region_max_size, const size_t page_size,
                          const char* base, const size_t size)
{
  if (TracePageSizes) {
    tty->print_cr("%s:  min=" SIZE_FORMAT " max=" SIZE_FORMAT
                  " pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT
                  " size=" SIZE_FORMAT,
                  str, region_min_size, region_max_size,
                  page_size, base, size);
  }
}
#endif  // #ifndef PRODUCT

// This is the working definition of a server class machine:
// >= 2 physical CPU's and >=2GB of memory, with some fuzz
// because the graphics memory (?) sometimes masks physical memory.
// If you want to change the definition of a server class machine
// on some OS or platform, e.g., >=4GB on Windows platforms,
// then you'll have to parameterize this method based on that state,
// as was done for logical processors here, or replicate and
// specialize this method for each platform.  (Or fix os to have
// some inheritance structure and use subclassing.  Sigh.)
// If you want some platform to always or never behave as a server
// class machine, change the setting of AlwaysActAsServerClassMachine
// and NeverActAsServerClassMachine in globals*.hpp.
bool os::is_server_class_machine() {
  // First check for the early returns
  if (NeverActAsServerClassMachine) {
    return false;
  }
  if (AlwaysActAsServerClassMachine) {
    return true;
  }
  // Then actually look at the machine
  bool         result            = false;
  const unsigned int    server_processors = 2;
  const julong server_memory     = 2UL * G;
  // We seem not to get our full complement of memory.
  //     We allow some part (1/8?) of the memory to be "missing",
  //     based on the sizes of DIMMs, and maybe graphics cards.
  const julong missing_memory   = 256UL * M;

  /* Is this a server class machine? */
  if ((os::active_processor_count() >= (int)server_processors) &&
      (os::physical_memory() >= (server_memory - missing_memory))) {
    const unsigned int logical_processors =
      VM_Version::logical_processors_per_package();
    if (logical_processors > 1) {
      const unsigned int physical_packages =
        os::active_processor_count() / logical_processors;
      if (physical_packages > server_processors) {
        result = true;
      }
    } else {
      result = true;
    }
  }
  return result;
}

void os::SuspendedThreadTask::run() {
  assert(Threads_lock->owned_by_self() || (_thread == VMThread::vm_thread()), "must have threads lock to call this");
  internal_do_task();
  _done = true;
}

bool os::create_stack_guard_pages(char* addr, size_t bytes) {
  return os::pd_create_stack_guard_pages(addr, bytes);
}

char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint) {
  char* result = pd_reserve_memory(bytes, addr, alignment_hint);
  if (result != NULL) {
    MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
  }

  return result;
}

char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint,
   MEMFLAGS flags) {
  char* result = pd_reserve_memory(bytes, addr, alignment_hint);
  if (result != NULL) {
    MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
    MemTracker::record_virtual_memory_type((address)result, flags);
  }

  return result;
}

char* os::attempt_reserve_memory_at(size_t bytes, char* addr) {
  char* result = pd_attempt_reserve_memory_at(bytes, addr);
  if (result != NULL) {
    MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
  }
  return result;
}

void os::split_reserved_memory(char *base, size_t size,
                                 size_t split, bool realloc) {
  pd_split_reserved_memory(base, size, split, realloc);
}

bool os::commit_memory(char* addr, size_t bytes, bool executable) {
  bool res = pd_commit_memory(addr, bytes, executable);
  if (res) {
    MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
  }
  return res;
}

bool os::commit_memory(char* addr, size_t size, size_t alignment_hint,
                              bool executable) {
  bool res = os::pd_commit_memory(addr, size, alignment_hint, executable);
  if (res) {
    MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
  }
  return res;
}

void os::commit_memory_or_exit(char* addr, size_t bytes, bool executable,
                               const char* mesg) {
  pd_commit_memory_or_exit(addr, bytes, executable, mesg);
  MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
}

void os::commit_memory_or_exit(char* addr, size_t size, size_t alignment_hint,
                               bool executable, const char* mesg) {
  os::pd_commit_memory_or_exit(addr, size, alignment_hint, executable, mesg);
  MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
}

bool os::uncommit_memory(char* addr, size_t bytes) {
  bool res;
  if (MemTracker::tracking_level() > NMT_minimal) {
    Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
    res = pd_uncommit_memory(addr, bytes);
    if (res) {
      tkr.record((address)addr, bytes);
    }
  } else {
    res = pd_uncommit_memory(addr, bytes);
  }
  return res;
}

bool os::release_memory(char* addr, size_t bytes) {
  bool res;
  if (MemTracker::tracking_level() > NMT_minimal) {
    Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
    res = pd_release_memory(addr, bytes);
    if (res) {
      tkr.record((address)addr, bytes);
    }
  } else {
    res = pd_release_memory(addr, bytes);
  }
  return res;
}

void os::pretouch_memory(char* start, char* end) {
  for (volatile char *p = start; p < end; p += os::vm_page_size()) {
    *p = 0;
  }
}

char* os::map_memory(int fd, const char* file_name, size_t file_offset,
                           char *addr, size_t bytes, bool read_only,
                           bool allow_exec) {
  char* result = pd_map_memory(fd, file_name, file_offset, addr, bytes, read_only, allow_exec);
  if (result != NULL) {
    MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
  }
  return result;
}

char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
                             char *addr, size_t bytes, bool read_only,
                             bool allow_exec) {
  return pd_remap_memory(fd, file_name, file_offset, addr, bytes,
                    read_only, allow_exec);
}

bool os::unmap_memory(char *addr, size_t bytes) {
  bool result;
  if (MemTracker::tracking_level() > NMT_minimal) {
    Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
    result = pd_unmap_memory(addr, bytes);
    if (result) {
      tkr.record((address)addr, bytes);
    }
  } else {
    result = pd_unmap_memory(addr, bytes);
  }
  return result;
}

void os::free_memory(char *addr, size_t bytes, size_t alignment_hint) {
  pd_free_memory(addr, bytes, alignment_hint);
}

void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
  pd_realign_memory(addr, bytes, alignment_hint);
}

#ifndef TARGET_OS_FAMILY_windows
/* try to switch state from state "from" to state "to"
 * returns the state set after the method is complete
 */
os::SuspendResume::State os::SuspendResume::switch_state(os::SuspendResume::State from,
                                                         os::SuspendResume::State to)
{
  os::SuspendResume::State result =
    (os::SuspendResume::State) Atomic::cmpxchg((jint) to, (jint *) &_state, (jint) from);
  if (result == from) {
    // success
    return to;
  }
  return result;
}
#endif

/////////////// Unit tests ///////////////

#ifndef PRODUCT

#define assert_eq(a,b) assert(a == b, err_msg(SIZE_FORMAT " != " SIZE_FORMAT, a, b))

class TestOS : AllStatic {
  static size_t small_page_size() {
    return os::vm_page_size();
  }

  static size_t large_page_size() {
    const size_t large_page_size_example = 4 * M;
    return os::page_size_for_region_aligned(large_page_size_example, 1);
  }

  static void test_page_size_for_region_aligned() {
    if (UseLargePages) {
      const size_t small_page = small_page_size();
      const size_t large_page = large_page_size();

      if (large_page > small_page) {
        size_t num_small_pages_in_large = large_page / small_page;
        size_t page = os::page_size_for_region_aligned(large_page, num_small_pages_in_large);

        assert_eq(page, small_page);
      }
    }
  }

  static void test_page_size_for_region_alignment() {
    if (UseLargePages) {
      const size_t small_page = small_page_size();
      const size_t large_page = large_page_size();
      if (large_page > small_page) {
        const size_t unaligned_region = large_page + 17;
        size_t page = os::page_size_for_region_aligned(unaligned_region, 1);
        assert_eq(page, small_page);

        const size_t num_pages = 5;
        const size_t aligned_region = large_page * num_pages;
        page = os::page_size_for_region_aligned(aligned_region, num_pages);
        assert_eq(page, large_page);
      }
    }
  }

  static void test_page_size_for_region_unaligned() {
    if (UseLargePages) {
      // Given exact page size, should return that page size.
      for (size_t i = 0; os::_page_sizes[i] != 0; i++) {
        size_t expected = os::_page_sizes[i];
        size_t actual = os::page_size_for_region_unaligned(expected, 1);
        assert_eq(expected, actual);
      }

      // Given slightly larger size than a page size, return the page size.
      for (size_t i = 0; os::_page_sizes[i] != 0; i++) {
        size_t expected = os::_page_sizes[i];
        size_t actual = os::page_size_for_region_unaligned(expected + 17, 1);
        assert_eq(expected, actual);
      }

      // Given a slightly smaller size than a page size,
      // return the next smaller page size.
      if (os::_page_sizes[1] > os::_page_sizes[0]) {
        size_t expected = os::_page_sizes[0];
        size_t actual = os::page_size_for_region_unaligned(os::_page_sizes[1] - 17, 1);
        assert_eq(actual, expected);
      }

      // Return small page size for values less than a small page.
      size_t small_page = small_page_size();
      size_t actual = os::page_size_for_region_unaligned(small_page - 17, 1);
      assert_eq(small_page, actual);
    }
  }

 public:
  static void run_tests() {
    test_page_size_for_region_aligned();
    test_page_size_for_region_alignment();
    test_page_size_for_region_unaligned();
  }
};

void TestOS_test() {
  TestOS::run_tests();
}

#endif // PRODUCT