1 /*
   2  * Copyright 1997-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // os defines the interface to operating system; this includes traditional
  26 // OS services (time, I/O) as well as other functionality with system-
  27 // dependent code.
  28 
  29 typedef void (*dll_func)(...);
  30 
  31 class Thread;
  32 class JavaThread;
  33 class Event;
  34 class DLL;
  35 class FileHandle;
  36 template<class E> class GrowableArray;
  37 
  38 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  39 
  40 // Platform-independent error return values from OS functions
  41 enum OSReturn {
  42   OS_OK         =  0,        // Operation was successful
  43   OS_ERR        = -1,        // Operation failed
  44   OS_INTRPT     = -2,        // Operation was interrupted
  45   OS_TIMEOUT    = -3,        // Operation timed out
  46   OS_NOMEM      = -5,        // Operation failed for lack of memory
  47   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  48 };
  49 
  50 enum ThreadPriority {        // JLS 20.20.1-3
  51   NoPriority       = -1,     // Initial non-priority value
  52   MinPriority      =  1,     // Minimum priority
  53   NormPriority     =  5,     // Normal (non-daemon) priority
  54   NearMaxPriority  =  9,     // High priority, used for VMThread
  55   MaxPriority      = 10      // Highest priority, used for WatcherThread
  56                              // ensures that VMThread doesn't starve profiler
  57 };
  58 
  59 // Typedef for structured exception handling support
  60 typedef void (*java_call_t)(JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
  61 
  62 class os: AllStatic {
  63  public:
  64   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
  65 
  66  private:
  67   static OSThread*          _starting_thread;
  68   static address            _polling_page;
  69   static volatile int32_t * _mem_serialize_page;
  70   static uintptr_t          _serialize_page_mask;
  71  public:
  72   static size_t             _page_sizes[page_sizes_max];
  73 
  74  private:
  75   static void init_page_sizes(size_t default_page_size) {
  76     _page_sizes[0] = default_page_size;
  77     _page_sizes[1] = 0; // sentinel
  78   }
  79 
  80  public:
  81   static void init(void);   // Called before command line parsing
  82   static jint init_2(void); // Called after command line parsing
  83 
  84   // File names are case-insensitive on windows only
  85   // Override me as needed
  86   static int    file_name_strcmp(const char* s1, const char* s2);
  87 
  88   static bool getenv(const char* name, char* buffer, int len);
  89   static bool have_special_privileges();
  90 
  91   static jlong  javaTimeMillis();
  92   static jlong  javaTimeNanos();
  93   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
  94   static void   run_periodic_checks();
  95 
  96 
  97   // Returns the elapsed time in seconds since the vm started.
  98   static double elapsedTime();
  99 
 100   // Returns real time in seconds since an arbitrary point
 101   // in the past.
 102   static bool getTimesSecs(double* process_real_time,
 103                            double* process_user_time,
 104                            double* process_system_time);
 105 
 106   // Interface to the performance counter
 107   static jlong elapsed_counter();
 108   static jlong elapsed_frequency();
 109 
 110   // The "virtual time" of a thread is the amount of time a thread has
 111   // actually run.  The first function indicates whether the OS supports
 112   // this functionality for the current thread, and if so:
 113   //   * the second enables vtime tracking (if that is required).
 114   //   * the third tells whether vtime is enabled.
 115   //   * the fourth returns the elapsed virtual time for the current
 116   //     thread.
 117   static bool supports_vtime();
 118   static bool enable_vtime();
 119   static bool vtime_enabled();
 120   static double elapsedVTime();
 121 
 122   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 123   // It is MT safe, but not async-safe, as reading time zone
 124   // information may require a lock on some platforms.
 125   static char*      local_time_string(char *buf, size_t buflen);
 126   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 127   // Fill in buffer with current local time as an ISO-8601 string.
 128   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 129   // Returns buffer, or NULL if it failed.
 130   static char* iso8601_time(char* buffer, size_t buffer_length);
 131 
 132   // Interface for detecting multiprocessor system
 133   static inline bool is_MP() {
 134     assert(_processor_count > 0, "invalid processor count");
 135     return _processor_count > 1;
 136   }
 137   static julong available_memory();
 138   static julong physical_memory();
 139   static julong allocatable_physical_memory(julong size);
 140   static bool is_server_class_machine();
 141 
 142   // number of CPUs
 143   static int processor_count() {
 144     return _processor_count;
 145   }
 146   static void set_processor_count(int count) { _processor_count = count; }
 147 
 148   // Returns the number of CPUs this process is currently allowed to run on.
 149   // Note that on some OSes this can change dynamically.
 150   static int active_processor_count();
 151 
 152   // Bind processes to processors.
 153   //     This is a two step procedure:
 154   //     first you generate a distribution of processes to processors,
 155   //     then you bind processes according to that distribution.
 156   // Compute a distribution for number of processes to processors.
 157   //    Stores the processor id's into the distribution array argument.
 158   //    Returns true if it worked, false if it didn't.
 159   static bool distribute_processes(uint length, uint* distribution);
 160   // Binds the current process to a processor.
 161   //    Returns true if it worked, false if it didn't.
 162   static bool bind_to_processor(uint processor_id);
 163 
 164   // Interface for stack banging (predetect possible stack overflow for
 165   // exception processing)  There are guard pages, and above that shadow
 166   // pages for stack overflow checking.
 167   static bool uses_stack_guard_pages();
 168   static bool allocate_stack_guard_pages();
 169   static void bang_stack_shadow_pages();
 170   static bool stack_shadow_pages_available(Thread *thread, methodHandle method);
 171 
 172   // OS interface to Virtual Memory
 173 
 174   // Return the default page size.
 175   static int    vm_page_size();
 176 
 177   // Return the page size to use for a region of memory.  The min_pages argument
 178   // is a hint intended to limit fragmentation; it says the returned page size
 179   // should be <= region_max_size / min_pages.  Because min_pages is a hint,
 180   // this routine may return a size larger than region_max_size / min_pages.
 181   //
 182   // The current implementation ignores min_pages if a larger page size is an
 183   // exact multiple of both region_min_size and region_max_size.  This allows
 184   // larger pages to be used when doing so would not cause fragmentation; in
 185   // particular, a single page can be used when region_min_size ==
 186   // region_max_size == a supported page size.
 187   static size_t page_size_for_region(size_t region_min_size,
 188                                      size_t region_max_size,
 189                                      uint min_pages);
 190 
 191   // Method for tracing page sizes returned by the above method; enabled by
 192   // TracePageSizes.  The region_{min,max}_size parameters should be the values
 193   // passed to page_size_for_region() and page_size should be the result of that
 194   // call.  The (optional) base and size parameters should come from the
 195   // ReservedSpace base() and size() methods.
 196   static void trace_page_sizes(const char* str, const size_t region_min_size,
 197                                const size_t region_max_size,
 198                                const size_t page_size,
 199                                const char* base = NULL,
 200                                const size_t size = 0) PRODUCT_RETURN;
 201 
 202   static int    vm_allocation_granularity();
 203   static char*  reserve_memory(size_t bytes, char* addr = 0,
 204                                size_t alignment_hint = 0);
 205   static char*  attempt_reserve_memory_at(size_t bytes, char* addr);
 206   static void   split_reserved_memory(char *base, size_t size,
 207                                       size_t split, bool realloc);
 208   static bool   commit_memory(char* addr, size_t bytes,
 209                               bool executable = false);
 210   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 211                               bool executable = false);
 212   static bool   uncommit_memory(char* addr, size_t bytes);
 213   static bool   release_memory(char* addr, size_t bytes);
 214 
 215   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 216   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 217                                bool is_committed = true);
 218 
 219   static bool   guard_memory(char* addr, size_t bytes);
 220   static bool   unguard_memory(char* addr, size_t bytes);
 221   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 222                            char *addr, size_t bytes, bool read_only = false,
 223                            bool allow_exec = false);
 224   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 225                              char *addr, size_t bytes, bool read_only,
 226                              bool allow_exec);
 227   static bool   unmap_memory(char *addr, size_t bytes);
 228   static void   free_memory(char *addr, size_t bytes);
 229   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 230 
 231   // NUMA-specific interface
 232   static bool   numa_has_static_binding();
 233   static bool   numa_has_group_homing();
 234   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 235   static void   numa_make_global(char *addr, size_t bytes);
 236   static size_t numa_get_groups_num();
 237   static size_t numa_get_leaf_groups(int *ids, size_t size);
 238   static bool   numa_topology_changed();
 239   static int    numa_get_group_id();
 240 
 241   // Page manipulation
 242   struct page_info {
 243     size_t size;
 244     int lgrp_id;
 245   };
 246   static bool   get_page_info(char *start, page_info* info);
 247   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 248 
 249   static char*  non_memory_address_word();
 250   // reserve, commit and pin the entire memory region
 251   static char*  reserve_memory_special(size_t size, char* addr = NULL,
 252                 bool executable = false);
 253   static bool   release_memory_special(char* addr, size_t bytes);
 254   static bool   large_page_init();
 255   static size_t large_page_size();
 256   static bool   can_commit_large_page_memory();
 257   static bool   can_execute_large_page_memory();
 258 
 259   // OS interface to polling page
 260   static address get_polling_page()             { return _polling_page; }
 261   static void    set_polling_page(address page) { _polling_page = page; }
 262   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 263   static void    make_polling_page_unreadable();
 264   static void    make_polling_page_readable();
 265 
 266   // Routines used to serialize the thread state without using membars
 267   static void    serialize_thread_states();
 268 
 269   // Since we write to the serialize page from every thread, we
 270   // want stores to be on unique cache lines whenever possible
 271   // in order to minimize CPU cross talk.  We pre-compute the
 272   // amount to shift the thread* to make this offset unique to
 273   // each thread.
 274   static int     get_serialize_page_shift_count() {
 275     return SerializePageShiftCount;
 276   }
 277 
 278   static void     set_serialize_page_mask(uintptr_t mask) {
 279     _serialize_page_mask = mask;
 280   }
 281 
 282   static unsigned int  get_serialize_page_mask() {
 283     return _serialize_page_mask;
 284   }
 285 
 286   static void    set_memory_serialize_page(address page);
 287 
 288   static address get_memory_serialize_page() {
 289     return (address)_mem_serialize_page;
 290   }
 291 
 292   static inline void write_memory_serialize_page(JavaThread *thread) {
 293     uintptr_t page_offset = ((uintptr_t)thread >>
 294                             get_serialize_page_shift_count()) &
 295                             get_serialize_page_mask();
 296     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
 297   }
 298 
 299   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
 300     if (UseMembar) return false;
 301     // Previously this function calculated the exact address of this
 302     // thread's serialize page, and checked if the faulting address
 303     // was equal.  However, some platforms mask off faulting addresses
 304     // to the page size, so now we just check that the address is
 305     // within the page.  This makes the thread argument unnecessary,
 306     // but we retain the NULL check to preserve existing behaviour.
 307     if (thread == NULL) return false;
 308     address page = (address) _mem_serialize_page;
 309     return addr >= page && addr < (page + os::vm_page_size());
 310   }
 311 
 312   static void block_on_serialize_page_trap();
 313 
 314   // threads
 315 
 316   enum ThreadType {
 317     vm_thread,
 318     cgc_thread,        // Concurrent GC thread
 319     pgc_thread,        // Parallel GC thread
 320     java_thread,
 321     compiler_thread,
 322     watcher_thread
 323   };
 324 
 325   static bool create_thread(Thread* thread,
 326                             ThreadType thr_type,
 327                             size_t stack_size = 0);
 328   static bool create_main_thread(JavaThread* thread);
 329   static bool create_attached_thread(JavaThread* thread);
 330   static void pd_start_thread(Thread* thread);
 331   static void start_thread(Thread* thread);
 332 
 333   static void initialize_thread();
 334   static void free_thread(OSThread* osthread);
 335 
 336   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 337   static intx current_thread_id();
 338   static int current_process_id();
 339   // hpi::read for calls from non native state
 340   // For performance, hpi::read is only callable from _thread_in_native
 341   static size_t read(int fd, void *buf, unsigned int nBytes);
 342   static int sleep(Thread* thread, jlong ms, bool interruptable);
 343   static int naked_sleep();
 344   static void infinite_sleep(); // never returns, use with CAUTION
 345   static void yield();        // Yields to all threads with same priority
 346   enum YieldResult {
 347     YIELD_SWITCHED = 1,         // caller descheduled, other ready threads exist & ran
 348     YIELD_NONEREADY = 0,        // No other runnable/ready threads.
 349                                 // platform-specific yield return immediately
 350     YIELD_UNKNOWN = -1          // Unknown: platform doesn't support _SWITCHED or _NONEREADY
 351     // YIELD_SWITCHED and YIELD_NONREADY imply the platform supports a "strong"
 352     // yield that can be used in lieu of blocking.
 353   } ;
 354   static YieldResult NakedYield () ;
 355   static void yield_all(int attempts = 0); // Yields to all other threads including lower priority
 356   static void loop_breaker(int attempts);  // called from within tight loops to possibly influence time-sharing
 357   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 358   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 359 
 360   static void interrupt(Thread* thread);
 361   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 362 
 363   static int pd_self_suspend_thread(Thread* thread);
 364 
 365   static ExtendedPC fetch_frame_from_context(void* ucVoid, intptr_t** sp, intptr_t** fp);
 366   static frame      fetch_frame_from_context(void* ucVoid);
 367 
 368   static ExtendedPC get_thread_pc(Thread *thread);
 369   static void breakpoint();
 370 
 371   static address current_stack_pointer();
 372   static address current_stack_base();
 373   static size_t current_stack_size();
 374 
 375   static int message_box(const char* title, const char* message);
 376   static char* do_you_want_to_debug(const char* message);
 377 
 378   // run cmd in a separate process and return its exit code; or -1 on failures
 379   static int fork_and_exec(char *cmd);
 380 
 381   // Set file to send error reports.
 382   static void set_error_file(const char *logfile);
 383 
 384   // os::exit() is merged with vm_exit()
 385   // static void exit(int num);
 386 
 387   // Terminate the VM, but don't exit the process
 388   static void shutdown();
 389 
 390   // Terminate with an error.  Default is to generate a core file on platforms
 391   // that support such things.  This calls shutdown() and then aborts.
 392   static void abort(bool dump_core = true);
 393 
 394   // Die immediately, no exit hook, no abort hook, no cleanup.
 395   static void die();
 396 
 397   // Reading directories.
 398   static DIR*           opendir(const char* dirname);
 399   static int            readdir_buf_size(const char *path);
 400   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
 401   static int            closedir(DIR* dirp);
 402 
 403   // Dynamic library extension
 404   static const char*    dll_file_extension();
 405 
 406   static const char*    get_temp_directory();
 407   static const char*    get_current_directory(char *buf, int buflen);
 408 
 409   // Builds a platform-specific full library path given a ld path and lib name
 410   static void           dll_build_name(char* buffer, size_t size,
 411                                        const char* pathname, const char* fname);
 412 
 413   // Symbol lookup, find nearest function name; basically it implements
 414   // dladdr() for all platforms. Name of the nearest function is copied
 415   // to buf. Distance from its base address is returned as offset.
 416   // If function name is not found, buf[0] is set to '\0' and offset is
 417   // set to -1.
 418   static bool dll_address_to_function_name(address addr, char* buf,
 419                                            int buflen, int* offset);
 420 
 421   // Locate DLL/DSO. On success, full path of the library is copied to
 422   // buf, and offset is set to be the distance between addr and the
 423   // library's base address. On failure, buf[0] is set to '\0' and
 424   // offset is set to -1.
 425   static bool dll_address_to_library_name(address addr, char* buf,
 426                                           int buflen, int* offset);
 427 
 428   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 429   static bool address_is_in_vm(address addr);
 430 
 431   // Loads .dll/.so and
 432   // in case of error it checks if .dll/.so was built for the
 433   // same architecture as Hotspot is running on
 434   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 435 
 436   // lookup symbol in a shared library
 437   static void* dll_lookup(void* handle, const char* name);
 438 
 439   // Print out system information; they are called by fatal error handler.
 440   // Output format may be different on different platforms.
 441   static void print_os_info(outputStream* st);
 442   static void print_cpu_info(outputStream* st);
 443   static void print_memory_info(outputStream* st);
 444   static void print_dll_info(outputStream* st);
 445   static void print_environment_variables(outputStream* st, const char** env_list, char* buffer, int len);
 446   static void print_context(outputStream* st, void* context);
 447   static void print_siginfo(outputStream* st, void* siginfo);
 448   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 449   static void print_date_and_time(outputStream* st);
 450 
 451   // The following two functions are used by fatal error handler to trace
 452   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 453   // frame.hpp/cpp assume thread is JavaThread, and also because different
 454   // OS/compiler may have different convention or provide different API to
 455   // walk C frames.
 456   //
 457   // We don't attempt to become a debugger, so we only follow frames if that
 458   // does not require a lookup in the unwind table, which is part of the binary
 459   // file but may be unsafe to read after a fatal error. So on x86, we can
 460   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 461   // possible to walk C stack without having the unwind table.
 462   static bool is_first_C_frame(frame *fr);
 463   static frame get_sender_for_C_frame(frame *fr);
 464 
 465   // return current frame. pc() and sp() are set to NULL on failure.
 466   static frame      current_frame();
 467 
 468   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 469 
 470   // returns a string to describe the exception/signal;
 471   // returns NULL if exception_code is not an OS exception/signal.
 472   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 473 
 474   // Returns native Java library, loads if necessary
 475   static void*    native_java_library();
 476 
 477   // Fills in path to jvm.dll/libjvm.so (this info used to find hpi).
 478   static void     jvm_path(char *buf, jint buflen);
 479 
 480   // JNI names
 481   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 482   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 483 
 484   // File conventions
 485   static const char* file_separator();
 486   static const char* line_separator();
 487   static const char* path_separator();
 488 
 489   // Init os specific system properties values
 490   static void init_system_properties_values();
 491 
 492   // IO operations, non-JVM_ version.
 493   static int stat(const char* path, struct stat* sbuf);
 494   static bool dir_is_empty(const char* path);
 495 
 496   // IO operations on binary files
 497   static int create_binary_file(const char* path, bool rewrite_existing);
 498   static jlong current_file_offset(int fd);
 499   static jlong seek_to_file_offset(int fd, jlong offset);
 500 
 501   // Thread Local Storage
 502   static int   allocate_thread_local_storage();
 503   static void  thread_local_storage_at_put(int index, void* value);
 504   static void* thread_local_storage_at(int index);
 505   static void  free_thread_local_storage(int index);
 506 
 507   // General allocation (must be MT-safe)
 508   static void* malloc  (size_t size);
 509   static void* realloc (void *memblock, size_t size);
 510   static void  free    (void *memblock);
 511   static bool  check_heap(bool force = false);      // verify C heap integrity
 512   static char* strdup(const char *);  // Like strdup
 513 
 514 #ifndef PRODUCT
 515   static int  num_mallocs;            // # of calls to malloc/realloc
 516   static size_t  alloc_bytes;         // # of bytes allocated
 517   static int  num_frees;              // # of calls to free
 518 #endif
 519 
 520   // Printing 64 bit integers
 521   static const char* jlong_format_specifier();
 522   static const char* julong_format_specifier();
 523 
 524   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 525   static void  signal_init();
 526   static void  signal_init_pd();
 527   static void  signal_notify(int signal_number);
 528   static void* signal(int signal_number, void* handler);
 529   static void  signal_raise(int signal_number);
 530   static int   signal_wait();
 531   static int   signal_lookup();
 532   static void* user_handler();
 533   static void  terminate_signal_thread();
 534   static int   sigexitnum_pd();
 535 
 536   // random number generation
 537   static long random();                    // return 32bit pseudorandom number
 538   static void init_random(long initval);   // initialize random sequence
 539 
 540   // Structured OS Exception support
 541   static void os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
 542 
 543   // JVMTI & JVM monitoring and management support
 544   // The thread_cpu_time() and current_thread_cpu_time() are only
 545   // supported if is_thread_cpu_time_supported() returns true.
 546   // They are not supported on Solaris T1.
 547 
 548   // Thread CPU Time - return the fast estimate on a platform
 549   // On Solaris - call gethrvtime (fast) - user time only
 550   // On Linux   - fast clock_gettime where available - user+sys
 551   //            - otherwise: very slow /proc fs - user+sys
 552   // On Windows - GetThreadTimes - user+sys
 553   static jlong current_thread_cpu_time();
 554   static jlong thread_cpu_time(Thread* t);
 555 
 556   // Thread CPU Time with user_sys_cpu_time parameter.
 557   //
 558   // If user_sys_cpu_time is true, user+sys time is returned.
 559   // Otherwise, only user time is returned
 560   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 561   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 562 
 563   // Return a bunch of info about the timers.
 564   // Note that the returned info for these two functions may be different
 565   // on some platforms
 566   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 567   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 568 
 569   static bool is_thread_cpu_time_supported();
 570 
 571   // System loadavg support.  Returns -1 if load average cannot be obtained.
 572   static int loadavg(double loadavg[], int nelem);
 573 
 574   // Hook for os specific jvm options that we don't want to abort on seeing
 575   static bool obsolete_option(const JavaVMOption *option);
 576 
 577   // Platform dependent stuff
 578   #include "incls/_os_pd.hpp.incl"
 579 
 580   // debugging support (mostly used by debug.cpp)
 581   static bool find(address pc) PRODUCT_RETURN0; // OS specific function to make sense out of an address
 582 
 583   static bool dont_yield();                     // when true, JVM_Yield() is nop
 584   static void print_statistics();
 585 
 586   // Thread priority helpers (implemented in OS-specific part)
 587   static OSReturn set_native_priority(Thread* thread, int native_prio);
 588   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 589   static int java_to_os_priority[MaxPriority + 1];
 590   // Hint to the underlying OS that a task switch would not be good.
 591   // Void return because it's a hint and can fail.
 592   static void hint_no_preempt();
 593 
 594   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 595   // Causes the VM to wait until an external stimulus has been applied
 596   // (for Unix, that stimulus is a signal, for Windows, an external
 597   // ResumeThread call)
 598   static void pause();
 599 
 600  protected:
 601   static long _rand_seed;                   // seed for random number generator
 602   static int _processor_count;              // number of processors
 603 
 604   static char* format_boot_path(const char* format_string,
 605                                 const char* home,
 606                                 int home_len,
 607                                 char fileSep,
 608                                 char pathSep);
 609   static bool set_boot_path(char fileSep, char pathSep);
 610   static char** split_path(const char* path, int* n);
 611 };
 612 
 613 // Note that "PAUSE" is almost always used with synchronization
 614 // so arguably we should provide Atomic::SpinPause() instead
 615 // of the global SpinPause() with C linkage.
 616 // It'd also be eligible for inlining on many platforms.
 617 
 618 extern "C" int SpinPause () ;
 619 extern "C" int SafeFetch32 (int * adr, int errValue) ;
 620 extern "C" intptr_t SafeFetchN (intptr_t * adr, intptr_t errValue) ;