src/share/vm/runtime/os.hpp

Fri, 12 Mar 2010 10:42:16 -0500

author
coleenp
date
Fri, 12 Mar 2010 10:42:16 -0500
changeset 1755
3b3d12e645e7
parent 1558
167c2986d91b
child 1907
c18cbe5936b8
permissions
-rw-r--r--

6929067: Stack guard pages should be removed when thread is detached
Summary: Add code to unmap stack guard area when thread is detached.
Reviewed-by: coleenp, kamg

     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  */
    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.
    29 typedef void (*dll_func)(...);
    31 class Thread;
    32 class JavaThread;
    33 class Event;
    34 class DLL;
    35 class FileHandle;
    36 template<class E> class GrowableArray;
    38 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
    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 };
    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 };
    59 // Typedef for structured exception handling support
    60 typedef void (*java_call_t)(JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
    62 class os: AllStatic {
    63  public:
    64   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
    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];
    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   }
    80  public:
    81   static void init(void);   // Called before command line parsing
    82   static jint init_2(void); // Called after command line parsing
    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);
    88   static bool getenv(const char* name, char* buffer, int len);
    89   static bool have_special_privileges();
    91   static jlong  javaTimeMillis();
    92   static jlong  javaTimeNanos();
    93   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
    94   static void   run_periodic_checks();
    97   // Returns the elapsed time in seconds since the vm started.
    98   static double elapsedTime();
   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);
   106   // Interface to the performance counter
   107   static jlong elapsed_counter();
   108   static jlong elapsed_frequency();
   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();
   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);
   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();
   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; }
   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();
   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);
   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);
   172   // OS interface to Virtual Memory
   174   // Return the default page size.
   175   static int    vm_page_size();
   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);
   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;
   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);
   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);
   219   static bool   guard_memory(char* addr, size_t bytes);
   220   static bool   unguard_memory(char* addr, size_t bytes);
   221   static bool   create_stack_guard_pages(char* addr, size_t bytes);
   222   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
   224   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
   225                            char *addr, size_t bytes, bool read_only = false,
   226                            bool allow_exec = false);
   227   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
   228                              char *addr, size_t bytes, bool read_only,
   229                              bool allow_exec);
   230   static bool   unmap_memory(char *addr, size_t bytes);
   231   static void   free_memory(char *addr, size_t bytes);
   232   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
   234   // NUMA-specific interface
   235   static bool   numa_has_static_binding();
   236   static bool   numa_has_group_homing();
   237   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
   238   static void   numa_make_global(char *addr, size_t bytes);
   239   static size_t numa_get_groups_num();
   240   static size_t numa_get_leaf_groups(int *ids, size_t size);
   241   static bool   numa_topology_changed();
   242   static int    numa_get_group_id();
   244   // Page manipulation
   245   struct page_info {
   246     size_t size;
   247     int lgrp_id;
   248   };
   249   static bool   get_page_info(char *start, page_info* info);
   250   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
   252   static char*  non_memory_address_word();
   253   // reserve, commit and pin the entire memory region
   254   static char*  reserve_memory_special(size_t size, char* addr = NULL,
   255                 bool executable = false);
   256   static bool   release_memory_special(char* addr, size_t bytes);
   257   static bool   large_page_init();
   258   static size_t large_page_size();
   259   static bool   can_commit_large_page_memory();
   260   static bool   can_execute_large_page_memory();
   262   // OS interface to polling page
   263   static address get_polling_page()             { return _polling_page; }
   264   static void    set_polling_page(address page) { _polling_page = page; }
   265   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
   266   static void    make_polling_page_unreadable();
   267   static void    make_polling_page_readable();
   269   // Routines used to serialize the thread state without using membars
   270   static void    serialize_thread_states();
   272   // Since we write to the serialize page from every thread, we
   273   // want stores to be on unique cache lines whenever possible
   274   // in order to minimize CPU cross talk.  We pre-compute the
   275   // amount to shift the thread* to make this offset unique to
   276   // each thread.
   277   static int     get_serialize_page_shift_count() {
   278     return SerializePageShiftCount;
   279   }
   281   static void     set_serialize_page_mask(uintptr_t mask) {
   282     _serialize_page_mask = mask;
   283   }
   285   static unsigned int  get_serialize_page_mask() {
   286     return _serialize_page_mask;
   287   }
   289   static void    set_memory_serialize_page(address page);
   291   static address get_memory_serialize_page() {
   292     return (address)_mem_serialize_page;
   293   }
   295   static inline void write_memory_serialize_page(JavaThread *thread) {
   296     uintptr_t page_offset = ((uintptr_t)thread >>
   297                             get_serialize_page_shift_count()) &
   298                             get_serialize_page_mask();
   299     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
   300   }
   302   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
   303     if (UseMembar) return false;
   304     // Previously this function calculated the exact address of this
   305     // thread's serialize page, and checked if the faulting address
   306     // was equal.  However, some platforms mask off faulting addresses
   307     // to the page size, so now we just check that the address is
   308     // within the page.  This makes the thread argument unnecessary,
   309     // but we retain the NULL check to preserve existing behaviour.
   310     if (thread == NULL) return false;
   311     address page = (address) _mem_serialize_page;
   312     return addr >= page && addr < (page + os::vm_page_size());
   313   }
   315   static void block_on_serialize_page_trap();
   317   // threads
   319   enum ThreadType {
   320     vm_thread,
   321     cgc_thread,        // Concurrent GC thread
   322     pgc_thread,        // Parallel GC thread
   323     java_thread,
   324     compiler_thread,
   325     watcher_thread
   326   };
   328   static bool create_thread(Thread* thread,
   329                             ThreadType thr_type,
   330                             size_t stack_size = 0);
   331   static bool create_main_thread(JavaThread* thread);
   332   static bool create_attached_thread(JavaThread* thread);
   333   static void pd_start_thread(Thread* thread);
   334   static void start_thread(Thread* thread);
   336   static void initialize_thread();
   337   static void free_thread(OSThread* osthread);
   339   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
   340   static intx current_thread_id();
   341   static int current_process_id();
   342   // hpi::read for calls from non native state
   343   // For performance, hpi::read is only callable from _thread_in_native
   344   static size_t read(int fd, void *buf, unsigned int nBytes);
   345   static int sleep(Thread* thread, jlong ms, bool interruptable);
   346   static int naked_sleep();
   347   static void infinite_sleep(); // never returns, use with CAUTION
   348   static void yield();        // Yields to all threads with same priority
   349   enum YieldResult {
   350     YIELD_SWITCHED = 1,         // caller descheduled, other ready threads exist & ran
   351     YIELD_NONEREADY = 0,        // No other runnable/ready threads.
   352                                 // platform-specific yield return immediately
   353     YIELD_UNKNOWN = -1          // Unknown: platform doesn't support _SWITCHED or _NONEREADY
   354     // YIELD_SWITCHED and YIELD_NONREADY imply the platform supports a "strong"
   355     // yield that can be used in lieu of blocking.
   356   } ;
   357   static YieldResult NakedYield () ;
   358   static void yield_all(int attempts = 0); // Yields to all other threads including lower priority
   359   static void loop_breaker(int attempts);  // called from within tight loops to possibly influence time-sharing
   360   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
   361   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
   363   static void interrupt(Thread* thread);
   364   static bool is_interrupted(Thread* thread, bool clear_interrupted);
   366   static int pd_self_suspend_thread(Thread* thread);
   368   static ExtendedPC fetch_frame_from_context(void* ucVoid, intptr_t** sp, intptr_t** fp);
   369   static frame      fetch_frame_from_context(void* ucVoid);
   371   static ExtendedPC get_thread_pc(Thread *thread);
   372   static void breakpoint();
   374   static address current_stack_pointer();
   375   static address current_stack_base();
   376   static size_t current_stack_size();
   378   static int message_box(const char* title, const char* message);
   379   static char* do_you_want_to_debug(const char* message);
   381   // run cmd in a separate process and return its exit code; or -1 on failures
   382   static int fork_and_exec(char *cmd);
   384   // Set file to send error reports.
   385   static void set_error_file(const char *logfile);
   387   // os::exit() is merged with vm_exit()
   388   // static void exit(int num);
   390   // Terminate the VM, but don't exit the process
   391   static void shutdown();
   393   // Terminate with an error.  Default is to generate a core file on platforms
   394   // that support such things.  This calls shutdown() and then aborts.
   395   static void abort(bool dump_core = true);
   397   // Die immediately, no exit hook, no abort hook, no cleanup.
   398   static void die();
   400   // Reading directories.
   401   static DIR*           opendir(const char* dirname);
   402   static int            readdir_buf_size(const char *path);
   403   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
   404   static int            closedir(DIR* dirp);
   406   // Dynamic library extension
   407   static const char*    dll_file_extension();
   409   static const char*    get_temp_directory();
   410   static const char*    get_current_directory(char *buf, int buflen);
   412   // Builds a platform-specific full library path given a ld path and lib name
   413   static void           dll_build_name(char* buffer, size_t size,
   414                                        const char* pathname, const char* fname);
   416   // Symbol lookup, find nearest function name; basically it implements
   417   // dladdr() for all platforms. Name of the nearest function is copied
   418   // to buf. Distance from its base address is returned as offset.
   419   // If function name is not found, buf[0] is set to '\0' and offset is
   420   // set to -1.
   421   static bool dll_address_to_function_name(address addr, char* buf,
   422                                            int buflen, int* offset);
   424   // Locate DLL/DSO. On success, full path of the library is copied to
   425   // buf, and offset is set to be the distance between addr and the
   426   // library's base address. On failure, buf[0] is set to '\0' and
   427   // offset is set to -1.
   428   static bool dll_address_to_library_name(address addr, char* buf,
   429                                           int buflen, int* offset);
   431   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
   432   static bool address_is_in_vm(address addr);
   434   // Loads .dll/.so and
   435   // in case of error it checks if .dll/.so was built for the
   436   // same architecture as Hotspot is running on
   437   static void* dll_load(const char *name, char *ebuf, int ebuflen);
   439   // lookup symbol in a shared library
   440   static void* dll_lookup(void* handle, const char* name);
   442   // Print out system information; they are called by fatal error handler.
   443   // Output format may be different on different platforms.
   444   static void print_os_info(outputStream* st);
   445   static void print_cpu_info(outputStream* st);
   446   static void print_memory_info(outputStream* st);
   447   static void print_dll_info(outputStream* st);
   448   static void print_environment_variables(outputStream* st, const char** env_list, char* buffer, int len);
   449   static void print_context(outputStream* st, void* context);
   450   static void print_siginfo(outputStream* st, void* siginfo);
   451   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
   452   static void print_date_and_time(outputStream* st);
   454   // The following two functions are used by fatal error handler to trace
   455   // native (C) frames. They are not part of frame.hpp/frame.cpp because
   456   // frame.hpp/cpp assume thread is JavaThread, and also because different
   457   // OS/compiler may have different convention or provide different API to
   458   // walk C frames.
   459   //
   460   // We don't attempt to become a debugger, so we only follow frames if that
   461   // does not require a lookup in the unwind table, which is part of the binary
   462   // file but may be unsafe to read after a fatal error. So on x86, we can
   463   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
   464   // possible to walk C stack without having the unwind table.
   465   static bool is_first_C_frame(frame *fr);
   466   static frame get_sender_for_C_frame(frame *fr);
   468   // return current frame. pc() and sp() are set to NULL on failure.
   469   static frame      current_frame();
   471   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
   473   // returns a string to describe the exception/signal;
   474   // returns NULL if exception_code is not an OS exception/signal.
   475   static const char* exception_name(int exception_code, char* buf, size_t buflen);
   477   // Returns native Java library, loads if necessary
   478   static void*    native_java_library();
   480   // Fills in path to jvm.dll/libjvm.so (this info used to find hpi).
   481   static void     jvm_path(char *buf, jint buflen);
   483   // JNI names
   484   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
   485   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
   487   // File conventions
   488   static const char* file_separator();
   489   static const char* line_separator();
   490   static const char* path_separator();
   492   // Init os specific system properties values
   493   static void init_system_properties_values();
   495   // IO operations, non-JVM_ version.
   496   static int stat(const char* path, struct stat* sbuf);
   497   static bool dir_is_empty(const char* path);
   499   // IO operations on binary files
   500   static int create_binary_file(const char* path, bool rewrite_existing);
   501   static jlong current_file_offset(int fd);
   502   static jlong seek_to_file_offset(int fd, jlong offset);
   504   // Thread Local Storage
   505   static int   allocate_thread_local_storage();
   506   static void  thread_local_storage_at_put(int index, void* value);
   507   static void* thread_local_storage_at(int index);
   508   static void  free_thread_local_storage(int index);
   510   // General allocation (must be MT-safe)
   511   static void* malloc  (size_t size);
   512   static void* realloc (void *memblock, size_t size);
   513   static void  free    (void *memblock);
   514   static bool  check_heap(bool force = false);      // verify C heap integrity
   515   static char* strdup(const char *);  // Like strdup
   517 #ifndef PRODUCT
   518   static int  num_mallocs;            // # of calls to malloc/realloc
   519   static size_t  alloc_bytes;         // # of bytes allocated
   520   static int  num_frees;              // # of calls to free
   521 #endif
   523   // Printing 64 bit integers
   524   static const char* jlong_format_specifier();
   525   static const char* julong_format_specifier();
   527   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
   528   static void  signal_init();
   529   static void  signal_init_pd();
   530   static void  signal_notify(int signal_number);
   531   static void* signal(int signal_number, void* handler);
   532   static void  signal_raise(int signal_number);
   533   static int   signal_wait();
   534   static int   signal_lookup();
   535   static void* user_handler();
   536   static void  terminate_signal_thread();
   537   static int   sigexitnum_pd();
   539   // random number generation
   540   static long random();                    // return 32bit pseudorandom number
   541   static void init_random(long initval);   // initialize random sequence
   543   // Structured OS Exception support
   544   static void os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
   546   // JVMTI & JVM monitoring and management support
   547   // The thread_cpu_time() and current_thread_cpu_time() are only
   548   // supported if is_thread_cpu_time_supported() returns true.
   549   // They are not supported on Solaris T1.
   551   // Thread CPU Time - return the fast estimate on a platform
   552   // On Solaris - call gethrvtime (fast) - user time only
   553   // On Linux   - fast clock_gettime where available - user+sys
   554   //            - otherwise: very slow /proc fs - user+sys
   555   // On Windows - GetThreadTimes - user+sys
   556   static jlong current_thread_cpu_time();
   557   static jlong thread_cpu_time(Thread* t);
   559   // Thread CPU Time with user_sys_cpu_time parameter.
   560   //
   561   // If user_sys_cpu_time is true, user+sys time is returned.
   562   // Otherwise, only user time is returned
   563   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
   564   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
   566   // Return a bunch of info about the timers.
   567   // Note that the returned info for these two functions may be different
   568   // on some platforms
   569   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
   570   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
   572   static bool is_thread_cpu_time_supported();
   574   // System loadavg support.  Returns -1 if load average cannot be obtained.
   575   static int loadavg(double loadavg[], int nelem);
   577   // Hook for os specific jvm options that we don't want to abort on seeing
   578   static bool obsolete_option(const JavaVMOption *option);
   580   // Platform dependent stuff
   581   #include "incls/_os_pd.hpp.incl"
   583   // debugging support (mostly used by debug.cpp)
   584   static bool find(address pc) PRODUCT_RETURN0; // OS specific function to make sense out of an address
   586   static bool dont_yield();                     // when true, JVM_Yield() is nop
   587   static void print_statistics();
   589   // Thread priority helpers (implemented in OS-specific part)
   590   static OSReturn set_native_priority(Thread* thread, int native_prio);
   591   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
   592   static int java_to_os_priority[MaxPriority + 1];
   593   // Hint to the underlying OS that a task switch would not be good.
   594   // Void return because it's a hint and can fail.
   595   static void hint_no_preempt();
   597   // Used at creation if requested by the diagnostic flag PauseAtStartup.
   598   // Causes the VM to wait until an external stimulus has been applied
   599   // (for Unix, that stimulus is a signal, for Windows, an external
   600   // ResumeThread call)
   601   static void pause();
   603  protected:
   604   static long _rand_seed;                   // seed for random number generator
   605   static int _processor_count;              // number of processors
   607   static char* format_boot_path(const char* format_string,
   608                                 const char* home,
   609                                 int home_len,
   610                                 char fileSep,
   611                                 char pathSep);
   612   static bool set_boot_path(char fileSep, char pathSep);
   613   static char** split_path(const char* path, int* n);
   614 };
   616 // Note that "PAUSE" is almost always used with synchronization
   617 // so arguably we should provide Atomic::SpinPause() instead
   618 // of the global SpinPause() with C linkage.
   619 // It'd also be eligible for inlining on many platforms.
   621 extern "C" int SpinPause () ;
   622 extern "C" int SafeFetch32 (int * adr, int errValue) ;
   623 extern "C" intptr_t SafeFetchN (intptr_t * adr, intptr_t errValue) ;

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