1 /*
   2  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_OS_HPP
  26 #define SHARE_VM_RUNTIME_OS_HPP
  27 
  28 #include "jvmtifiles/jvmti.h"
  29 #include "runtime/atomic.hpp"
  30 #include "runtime/extendedPC.hpp"
  31 #include "runtime/handles.hpp"
  32 #include "utilities/top.hpp"
  33 #ifdef TARGET_OS_FAMILY_linux
  34 # include "jvm_linux.h"
  35 # include <setjmp.h>
  36 #endif
  37 #ifdef TARGET_OS_FAMILY_solaris
  38 # include "jvm_solaris.h"
  39 # include <setjmp.h>
  40 #endif
  41 #ifdef TARGET_OS_FAMILY_windows
  42 # include "jvm_windows.h"
  43 #endif
  44 #ifdef TARGET_OS_FAMILY_bsd
  45 # include "jvm_bsd.h"
  46 # include <setjmp.h>
  47 #endif
  48 
  49 class AgentLibrary;
  50 
  51 // os defines the interface to operating system; this includes traditional
  52 // OS services (time, I/O) as well as other functionality with system-
  53 // dependent code.
  54 
  55 typedef void (*dll_func)(...);
  56 
  57 class Thread;
  58 class JavaThread;
  59 class Event;
  60 class DLL;
  61 class FileHandle;
  62 template<class E> class GrowableArray;
  63 
  64 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  65 
  66 // Platform-independent error return values from OS functions
  67 enum OSReturn {
  68   OS_OK         =  0,        // Operation was successful
  69   OS_ERR        = -1,        // Operation failed
  70   OS_INTRPT     = -2,        // Operation was interrupted
  71   OS_TIMEOUT    = -3,        // Operation timed out
  72   OS_NOMEM      = -5,        // Operation failed for lack of memory
  73   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  74 };
  75 
  76 enum ThreadPriority {        // JLS 20.20.1-3
  77   NoPriority       = -1,     // Initial non-priority value
  78   MinPriority      =  1,     // Minimum priority
  79   NormPriority     =  5,     // Normal (non-daemon) priority
  80   NearMaxPriority  =  9,     // High priority, used for VMThread
  81   MaxPriority      = 10,     // Highest priority, used for WatcherThread
  82                              // ensures that VMThread doesn't starve profiler
  83   CriticalPriority = 11      // Critical thread priority
  84 };
  85 
  86 // Executable parameter flag for os::commit_memory() and
  87 // os::commit_memory_or_exit().
  88 const bool ExecMem = true;
  89 
  90 // Typedef for structured exception handling support
  91 typedef void (*java_call_t)(JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
  92 
  93 class os: AllStatic {
  94   friend class VMStructs;
  95 
  96  public:
  97   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
  98 
  99  private:
 100   static OSThread*          _starting_thread;
 101   static address            _polling_page;
 102   static volatile int32_t * _mem_serialize_page;
 103   static uintptr_t          _serialize_page_mask;
 104  public:
 105   static size_t             _page_sizes[page_sizes_max];
 106 
 107  private:
 108   static void init_page_sizes(size_t default_page_size) {
 109     _page_sizes[0] = default_page_size;
 110     _page_sizes[1] = 0; // sentinel
 111   }
 112 
 113   static char*  pd_reserve_memory(size_t bytes, char* addr = 0,
 114                                size_t alignment_hint = 0);
 115   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr);
 116   static void   pd_split_reserved_memory(char *base, size_t size,
 117                                       size_t split, bool realloc);
 118   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
 119   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
 120                                  bool executable);
 121   // Same as pd_commit_memory() that either succeeds or calls
 122   // vm_exit_out_of_memory() with the specified mesg.
 123   static void   pd_commit_memory_or_exit(char* addr, size_t bytes,
 124                                          bool executable, const char* mesg);
 125   static void   pd_commit_memory_or_exit(char* addr, size_t size,
 126                                          size_t alignment_hint,
 127                                          bool executable, const char* mesg);
 128   static bool   pd_uncommit_memory(char* addr, size_t bytes);
 129   static bool   pd_release_memory(char* addr, size_t bytes);
 130 
 131   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
 132                            char *addr, size_t bytes, bool read_only = false,
 133                            bool allow_exec = false);
 134   static char*  pd_remap_memory(int fd, const char* file_name, size_t file_offset,
 135                              char *addr, size_t bytes, bool read_only,
 136                              bool allow_exec);
 137   static bool   pd_unmap_memory(char *addr, size_t bytes);
 138   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
 139   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 140 
 141 
 142  public:
 143   static void init(void);                      // Called before command line parsing
 144   static void init_before_ergo(void);          // Called after command line parsing
 145                                                // before VM ergonomics processing.
 146   static jint init_2(void);                    // Called after command line parsing
 147                                                // and VM ergonomics processing
 148   static void init_globals(void) {             // Called from init_globals() in init.cpp
 149     init_globals_ext();
 150   }
 151   static void init_3(void);                    // Called at the end of vm init
 152 
 153   // File names are case-insensitive on windows only
 154   // Override me as needed
 155   static int    file_name_strcmp(const char* s1, const char* s2);
 156 
 157   static bool getenv(const char* name, char* buffer, int len);
 158   static bool have_special_privileges();
 159 
 160   static jlong  javaTimeMillis();
 161   static jlong  javaTimeNanos();
 162   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
 163   static void   run_periodic_checks();
 164   static bool   supports_monotonic_clock();
 165 
 166 
 167   // Returns the elapsed time in seconds since the vm started.
 168   static double elapsedTime();
 169 
 170   // Returns real time in seconds since an arbitrary point
 171   // in the past.
 172   static bool getTimesSecs(double* process_real_time,
 173                            double* process_user_time,
 174                            double* process_system_time);
 175 
 176   // Interface to the performance counter
 177   static jlong elapsed_counter();
 178   static jlong elapsed_frequency();
 179 
 180   // The "virtual time" of a thread is the amount of time a thread has
 181   // actually run.  The first function indicates whether the OS supports
 182   // this functionality for the current thread, and if so:
 183   //   * the second enables vtime tracking (if that is required).
 184   //   * the third tells whether vtime is enabled.
 185   //   * the fourth returns the elapsed virtual time for the current
 186   //     thread.
 187   static bool supports_vtime();
 188   static bool enable_vtime();
 189   static bool vtime_enabled();
 190   static double elapsedVTime();
 191 
 192   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 193   // It is MT safe, but not async-safe, as reading time zone
 194   // information may require a lock on some platforms.
 195   static char*      local_time_string(char *buf, size_t buflen);
 196   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 197   // Fill in buffer with current local time as an ISO-8601 string.
 198   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 199   // Returns buffer, or NULL if it failed.
 200   static char* iso8601_time(char* buffer, size_t buffer_length);
 201 
 202   // Interface for detecting multiprocessor system
 203   static inline bool is_MP() {
 204     assert(_processor_count > 0, "invalid processor count");
 205     return _processor_count > 1 || AssumeMP;
 206   }
 207   static julong available_memory();
 208   static julong physical_memory();
 209   static bool has_allocatable_memory_limit(julong* limit);
 210   static bool is_server_class_machine();
 211 
 212   // number of CPUs
 213   static int processor_count() {
 214     return _processor_count;
 215   }
 216   static void set_processor_count(int count) { _processor_count = count; }
 217 
 218   // Returns the number of CPUs this process is currently allowed to run on.
 219   // Note that on some OSes this can change dynamically.
 220   static int active_processor_count();
 221 
 222   // Bind processes to processors.
 223   //     This is a two step procedure:
 224   //     first you generate a distribution of processes to processors,
 225   //     then you bind processes according to that distribution.
 226   // Compute a distribution for number of processes to processors.
 227   //    Stores the processor id's into the distribution array argument.
 228   //    Returns true if it worked, false if it didn't.
 229   static bool distribute_processes(uint length, uint* distribution);
 230   // Binds the current process to a processor.
 231   //    Returns true if it worked, false if it didn't.
 232   static bool bind_to_processor(uint processor_id);
 233 
 234   // Give a name to the current thread.
 235   static void set_native_thread_name(const char *name);
 236 
 237   // Interface for stack banging (predetect possible stack overflow for
 238   // exception processing)  There are guard pages, and above that shadow
 239   // pages for stack overflow checking.
 240   static bool uses_stack_guard_pages();
 241   static bool allocate_stack_guard_pages();
 242   static void bang_stack_shadow_pages();
 243   static bool stack_shadow_pages_available(Thread *thread, methodHandle method);
 244 
 245   // OS interface to Virtual Memory
 246 
 247   // Return the default page size.
 248   static int    vm_page_size();
 249 
 250   // Return the page size to use for a region of memory.  The min_pages argument
 251   // is a hint intended to limit fragmentation; it says the returned page size
 252   // should be <= region_max_size / min_pages.  Because min_pages is a hint,
 253   // this routine may return a size larger than region_max_size / min_pages.
 254   //
 255   // The current implementation ignores min_pages if a larger page size is an
 256   // exact multiple of both region_min_size and region_max_size.  This allows
 257   // larger pages to be used when doing so would not cause fragmentation; in
 258   // particular, a single page can be used when region_min_size ==
 259   // region_max_size == a supported page size.
 260   static size_t page_size_for_region(size_t region_min_size,
 261                                      size_t region_max_size,
 262                                      uint min_pages);
 263   // Return the largest page size that can be used
 264   static size_t max_page_size() {
 265     // The _page_sizes array is sorted in descending order.
 266     return _page_sizes[0];
 267   }
 268 
 269   // Methods for tracing page sizes returned by the above method; enabled by
 270   // TracePageSizes.  The region_{min,max}_size parameters should be the values
 271   // passed to page_size_for_region() and page_size should be the result of that
 272   // call.  The (optional) base and size parameters should come from the
 273   // ReservedSpace base() and size() methods.
 274   static void trace_page_sizes(const char* str, const size_t* page_sizes,
 275                                int count) PRODUCT_RETURN;
 276   static void trace_page_sizes(const char* str, const size_t region_min_size,
 277                                const size_t region_max_size,
 278                                const size_t page_size,
 279                                const char* base = NULL,
 280                                const size_t size = 0) PRODUCT_RETURN;
 281 
 282   static int    vm_allocation_granularity();
 283   static char*  reserve_memory(size_t bytes, char* addr = 0,
 284                                size_t alignment_hint = 0);
 285   static char*  reserve_memory(size_t bytes, char* addr,
 286                                size_t alignment_hint, MEMFLAGS flags);
 287   static char*  reserve_memory_aligned(size_t size, size_t alignment);
 288   static char*  attempt_reserve_memory_at(size_t bytes, char* addr);
 289   static void   split_reserved_memory(char *base, size_t size,
 290                                       size_t split, bool realloc);
 291   static bool   commit_memory(char* addr, size_t bytes, bool executable);
 292   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 293                               bool executable);
 294   // Same as commit_memory() that either succeeds or calls
 295   // vm_exit_out_of_memory() with the specified mesg.
 296   static void   commit_memory_or_exit(char* addr, size_t bytes,
 297                                       bool executable, const char* mesg);
 298   static void   commit_memory_or_exit(char* addr, size_t size,
 299                                       size_t alignment_hint,
 300                                       bool executable, const char* mesg);
 301   static bool   uncommit_memory(char* addr, size_t bytes);
 302   static bool   release_memory(char* addr, size_t bytes);
 303 
 304   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 305   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 306                                bool is_committed = true);
 307 
 308   static bool   guard_memory(char* addr, size_t bytes);
 309   static bool   unguard_memory(char* addr, size_t bytes);
 310   static bool   create_stack_guard_pages(char* addr, size_t bytes);
 311   static bool   pd_create_stack_guard_pages(char* addr, size_t bytes);
 312   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
 313 
 314   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 315                            char *addr, size_t bytes, bool read_only = false,
 316                            bool allow_exec = false);
 317   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 318                              char *addr, size_t bytes, bool read_only,
 319                              bool allow_exec);
 320   static bool   unmap_memory(char *addr, size_t bytes);
 321   static void   free_memory(char *addr, size_t bytes, size_t alignment_hint);
 322   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 323 
 324   // NUMA-specific interface
 325   static bool   numa_has_static_binding();
 326   static bool   numa_has_group_homing();
 327   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 328   static void   numa_make_global(char *addr, size_t bytes);
 329   static size_t numa_get_groups_num();
 330   static size_t numa_get_leaf_groups(int *ids, size_t size);
 331   static bool   numa_topology_changed();
 332   static int    numa_get_group_id();
 333 
 334   // Page manipulation
 335   struct page_info {
 336     size_t size;
 337     int lgrp_id;
 338   };
 339   static bool   get_page_info(char *start, page_info* info);
 340   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 341 
 342   static char*  non_memory_address_word();
 343   // reserve, commit and pin the entire memory region
 344   static char*  reserve_memory_special(size_t size, size_t alignment,
 345                                        char* addr, bool executable);
 346   static bool   release_memory_special(char* addr, size_t bytes);
 347   static void   large_page_init();
 348   static size_t large_page_size();
 349   static bool   can_commit_large_page_memory();
 350   static bool   can_execute_large_page_memory();
 351 
 352   // OS interface to polling page
 353   static address get_polling_page()             { return _polling_page; }
 354   static void    set_polling_page(address page) { _polling_page = page; }
 355   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 356   static void    make_polling_page_unreadable();
 357   static void    make_polling_page_readable();
 358 
 359   // Routines used to serialize the thread state without using membars
 360   static void    serialize_thread_states();
 361 
 362   // Since we write to the serialize page from every thread, we
 363   // want stores to be on unique cache lines whenever possible
 364   // in order to minimize CPU cross talk.  We pre-compute the
 365   // amount to shift the thread* to make this offset unique to
 366   // each thread.
 367   static int     get_serialize_page_shift_count() {
 368     return SerializePageShiftCount;
 369   }
 370 
 371   static void     set_serialize_page_mask(uintptr_t mask) {
 372     _serialize_page_mask = mask;
 373   }
 374 
 375   static unsigned int  get_serialize_page_mask() {
 376     return _serialize_page_mask;
 377   }
 378 
 379   static void    set_memory_serialize_page(address page);
 380 
 381   static address get_memory_serialize_page() {
 382     return (address)_mem_serialize_page;
 383   }
 384 
 385   static inline void write_memory_serialize_page(JavaThread *thread) {
 386     uintptr_t page_offset = ((uintptr_t)thread >>
 387                             get_serialize_page_shift_count()) &
 388                             get_serialize_page_mask();
 389     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
 390   }
 391 
 392   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
 393     if (UseMembar) return false;
 394     // Previously this function calculated the exact address of this
 395     // thread's serialize page, and checked if the faulting address
 396     // was equal.  However, some platforms mask off faulting addresses
 397     // to the page size, so now we just check that the address is
 398     // within the page.  This makes the thread argument unnecessary,
 399     // but we retain the NULL check to preserve existing behavior.
 400     if (thread == NULL) return false;
 401     address page = (address) _mem_serialize_page;
 402     return addr >= page && addr < (page + os::vm_page_size());
 403   }
 404 
 405   static void block_on_serialize_page_trap();
 406 
 407   // threads
 408 
 409   enum ThreadType {
 410     vm_thread,
 411     cgc_thread,        // Concurrent GC thread
 412     pgc_thread,        // Parallel GC thread
 413     java_thread,
 414     compiler_thread,
 415     watcher_thread,
 416     os_thread
 417   };
 418 
 419   static bool create_thread(Thread* thread,
 420                             ThreadType thr_type,
 421                             size_t stack_size = 0);
 422   static bool create_main_thread(JavaThread* thread);
 423   static bool create_attached_thread(JavaThread* thread);
 424   static void pd_start_thread(Thread* thread);
 425   static void start_thread(Thread* thread);
 426 
 427   static void initialize_thread(Thread* thr);
 428   static void free_thread(OSThread* osthread);
 429 
 430   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 431   static intx current_thread_id();
 432   static int current_process_id();
 433   static int sleep(Thread* thread, jlong ms, bool interruptable);
 434   // Short standalone OS sleep suitable for slow path spin loop.
 435   // Ignores Thread.interrupt() (so keep it short).
 436   // ms = 0, will sleep for the least amount of time allowed by the OS.
 437   static void naked_short_sleep(jlong ms);
 438   static void infinite_sleep(); // never returns, use with CAUTION
 439   static void yield();        // Yields to all threads with same priority
 440   enum YieldResult {
 441     YIELD_SWITCHED = 1,         // caller descheduled, other ready threads exist & ran
 442     YIELD_NONEREADY = 0,        // No other runnable/ready threads.
 443                                 // platform-specific yield return immediately
 444     YIELD_UNKNOWN = -1          // Unknown: platform doesn't support _SWITCHED or _NONEREADY
 445     // YIELD_SWITCHED and YIELD_NONREADY imply the platform supports a "strong"
 446     // yield that can be used in lieu of blocking.
 447   } ;
 448   static YieldResult NakedYield () ;
 449   static void yield_all(int attempts = 0); // Yields to all other threads including lower priority
 450   static void loop_breaker(int attempts);  // called from within tight loops to possibly influence time-sharing
 451   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 452   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 453 
 454   static void interrupt(Thread* thread);
 455   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 456 
 457   static int pd_self_suspend_thread(Thread* thread);
 458 
 459   static ExtendedPC fetch_frame_from_context(void* ucVoid, intptr_t** sp, intptr_t** fp);
 460   static frame      fetch_frame_from_context(void* ucVoid);
 461 
 462   static ExtendedPC get_thread_pc(Thread *thread);
 463   static void breakpoint();
 464 
 465   static address current_stack_pointer();
 466   static address current_stack_base();
 467   static size_t current_stack_size();
 468 
 469   static void verify_stack_alignment() PRODUCT_RETURN;
 470 
 471   static int message_box(const char* title, const char* message);
 472   static char* do_you_want_to_debug(const char* message);
 473 
 474   // run cmd in a separate process and return its exit code; or -1 on failures
 475   static int fork_and_exec(char *cmd);
 476 
 477   // Set file to send error reports.
 478   static void set_error_file(const char *logfile);
 479 
 480   // os::exit() is merged with vm_exit()
 481   // static void exit(int num);
 482 
 483   // Terminate the VM, but don't exit the process
 484   static void shutdown();
 485 
 486   // Terminate with an error.  Default is to generate a core file on platforms
 487   // that support such things.  This calls shutdown() and then aborts.
 488   static void abort(bool dump_core = true);
 489 
 490   // Die immediately, no exit hook, no abort hook, no cleanup.
 491   static void die();
 492 
 493   // File i/o operations
 494   static const int default_file_open_flags();
 495   static int open(const char *path, int oflag, int mode);
 496   static FILE* open(int fd, const char* mode);
 497   static int close(int fd);
 498   static jlong lseek(int fd, jlong offset, int whence);
 499   static char* native_path(char *path);
 500   static int ftruncate(int fd, jlong length);
 501   static int fsync(int fd);
 502   static int available(int fd, jlong *bytes);
 503 
 504   //File i/o operations
 505 
 506   static size_t read(int fd, void *buf, unsigned int nBytes);
 507   static size_t restartable_read(int fd, void *buf, unsigned int nBytes);
 508   static size_t write(int fd, const void *buf, unsigned int nBytes);
 509 
 510   // Reading directories.
 511   static DIR*           opendir(const char* dirname);
 512   static int            readdir_buf_size(const char *path);
 513   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
 514   static int            closedir(DIR* dirp);
 515 
 516   // Dynamic library extension
 517   static const char*    dll_file_extension();
 518 
 519   static const char*    get_temp_directory();
 520   static const char*    get_current_directory(char *buf, size_t buflen);
 521 
 522   // Builds a platform-specific full library path given a ld path and lib name
 523   // Returns true if buffer contains full path to existing file, false otherwise
 524   static bool           dll_build_name(char* buffer, size_t size,
 525                                        const char* pathname, const char* fname);
 526 
 527   // Symbol lookup, find nearest function name; basically it implements
 528   // dladdr() for all platforms. Name of the nearest function is copied
 529   // to buf. Distance from its base address is optionally returned as offset.
 530   // If function name is not found, buf[0] is set to '\0' and offset is
 531   // set to -1 (if offset is non-NULL).
 532   static bool dll_address_to_function_name(address addr, char* buf,
 533                                            int buflen, int* offset);
 534 
 535   // Locate DLL/DSO. On success, full path of the library is copied to
 536   // buf, and offset is optionally set to be the distance between addr
 537   // and the library's base address. On failure, buf[0] is set to '\0'
 538   // and offset is set to -1 (if offset is non-NULL).
 539   static bool dll_address_to_library_name(address addr, char* buf,
 540                                           int buflen, int* offset);
 541 
 542   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 543   static bool address_is_in_vm(address addr);
 544 
 545   // Loads .dll/.so and
 546   // in case of error it checks if .dll/.so was built for the
 547   // same architecture as HotSpot is running on
 548   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 549 
 550   // lookup symbol in a shared library
 551   static void* dll_lookup(void* handle, const char* name);
 552 
 553   // Unload library
 554   static void  dll_unload(void *lib);
 555 
 556   // Return the handle of this process
 557   static void* get_default_process_handle();
 558 
 559   // Check for static linked agent library
 560   static bool find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 561                                  size_t syms_len);
 562 
 563   // Find agent entry point
 564   static void *find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 565                                    const char *syms[], size_t syms_len);
 566 
 567   // Print out system information; they are called by fatal error handler.
 568   // Output format may be different on different platforms.
 569   static void print_os_info(outputStream* st);
 570   static void print_os_info_brief(outputStream* st);
 571   static void print_cpu_info(outputStream* st);
 572   static void pd_print_cpu_info(outputStream* st);
 573   static void print_memory_info(outputStream* st);
 574   static void print_dll_info(outputStream* st);
 575   static void print_environment_variables(outputStream* st, const char** env_list, char* buffer, int len);
 576   static void print_context(outputStream* st, void* context);
 577   static void print_register_info(outputStream* st, void* context);
 578   static void print_siginfo(outputStream* st, void* siginfo);
 579   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 580   static void print_date_and_time(outputStream* st);
 581 
 582   static void print_location(outputStream* st, intptr_t x, bool verbose = false);
 583   static size_t lasterror(char *buf, size_t len);
 584   static int get_last_error();
 585 
 586   // Determines whether the calling process is being debugged by a user-mode debugger.
 587   static bool is_debugger_attached();
 588 
 589   // wait for a key press if PauseAtExit is set
 590   static void wait_for_keypress_at_exit(void);
 591 
 592   // The following two functions are used by fatal error handler to trace
 593   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 594   // frame.hpp/cpp assume thread is JavaThread, and also because different
 595   // OS/compiler may have different convention or provide different API to
 596   // walk C frames.
 597   //
 598   // We don't attempt to become a debugger, so we only follow frames if that
 599   // does not require a lookup in the unwind table, which is part of the binary
 600   // file but may be unsafe to read after a fatal error. So on x86, we can
 601   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 602   // possible to walk C stack without having the unwind table.
 603   static bool is_first_C_frame(frame *fr);
 604   static frame get_sender_for_C_frame(frame *fr);
 605 
 606   // return current frame. pc() and sp() are set to NULL on failure.
 607   static frame      current_frame();
 608 
 609   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 610 
 611   // returns a string to describe the exception/signal;
 612   // returns NULL if exception_code is not an OS exception/signal.
 613   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 614 
 615   // Returns native Java library, loads if necessary
 616   static void*    native_java_library();
 617 
 618   // Fills in path to jvm.dll/libjvm.so (used by the Disassembler)
 619   static void     jvm_path(char *buf, jint buflen);
 620 
 621   // Returns true if we are running in a headless jre.
 622   static bool     is_headless_jre();
 623 
 624   // JNI names
 625   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 626   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 627 
 628   // File conventions
 629   static const char* file_separator();
 630   static const char* line_separator();
 631   static const char* path_separator();
 632 
 633   // Init os specific system properties values
 634   static void init_system_properties_values();
 635 
 636   // IO operations, non-JVM_ version.
 637   static int stat(const char* path, struct stat* sbuf);
 638   static bool dir_is_empty(const char* path);
 639 
 640   // IO operations on binary files
 641   static int create_binary_file(const char* path, bool rewrite_existing);
 642   static jlong current_file_offset(int fd);
 643   static jlong seek_to_file_offset(int fd, jlong offset);
 644 
 645   // Thread Local Storage
 646   static int   allocate_thread_local_storage();
 647   static void  thread_local_storage_at_put(int index, void* value);
 648   static void* thread_local_storage_at(int index);
 649   static void  free_thread_local_storage(int index);
 650 
 651   // Stack walk
 652   static address get_caller_pc(int n = 0);
 653 
 654   // General allocation (must be MT-safe)
 655   static void* malloc  (size_t size, MEMFLAGS flags, address caller_pc = 0);
 656   static void* realloc (void *memblock, size_t size, MEMFLAGS flags, address caller_pc = 0);
 657   static void  free    (void *memblock, MEMFLAGS flags = mtNone);
 658   static bool  check_heap(bool force = false);      // verify C heap integrity
 659   static char* strdup(const char *, MEMFLAGS flags = mtInternal);  // Like strdup
 660 
 661 #ifndef PRODUCT
 662   static julong num_mallocs;         // # of calls to malloc/realloc
 663   static julong alloc_bytes;         // # of bytes allocated
 664   static julong num_frees;           // # of calls to free
 665   static julong free_bytes;          // # of bytes freed
 666 #endif
 667 
 668   // SocketInterface (ex HPI SocketInterface )
 669   static int socket(int domain, int type, int protocol);
 670   static int socket_close(int fd);
 671   static int socket_shutdown(int fd, int howto);
 672   static int recv(int fd, char* buf, size_t nBytes, uint flags);
 673   static int send(int fd, char* buf, size_t nBytes, uint flags);
 674   static int raw_send(int fd, char* buf, size_t nBytes, uint flags);
 675   static int timeout(int fd, long timeout);
 676   static int listen(int fd, int count);
 677   static int connect(int fd, struct sockaddr* him, socklen_t len);
 678   static int bind(int fd, struct sockaddr* him, socklen_t len);
 679   static int accept(int fd, struct sockaddr* him, socklen_t* len);
 680   static int recvfrom(int fd, char* buf, size_t nbytes, uint flags,
 681                       struct sockaddr* from, socklen_t* fromlen);
 682   static int get_sock_name(int fd, struct sockaddr* him, socklen_t* len);
 683   static int sendto(int fd, char* buf, size_t len, uint flags,
 684                     struct sockaddr* to, socklen_t tolen);
 685   static int socket_available(int fd, jint* pbytes);
 686 
 687   static int get_sock_opt(int fd, int level, int optname,
 688                           char* optval, socklen_t* optlen);
 689   static int set_sock_opt(int fd, int level, int optname,
 690                           const char* optval, socklen_t optlen);
 691   static int get_host_name(char* name, int namelen);
 692 
 693   static struct hostent* get_host_by_name(char* name);
 694 
 695   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 696   static void  signal_init();
 697   static void  signal_init_pd();
 698   static void  signal_notify(int signal_number);
 699   static void* signal(int signal_number, void* handler);
 700   static void  signal_raise(int signal_number);
 701   static int   signal_wait();
 702   static int   signal_lookup();
 703   static void* user_handler();
 704   static void  terminate_signal_thread();
 705   static int   sigexitnum_pd();
 706 
 707   // random number generation
 708   static long random();                    // return 32bit pseudorandom number
 709   static void init_random(long initval);   // initialize random sequence
 710 
 711   // Structured OS Exception support
 712   static void os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
 713 
 714   // On Windows this will create an actual minidump, on Linux/Solaris it will simply check core dump limits
 715   static void check_or_create_dump(void* exceptionRecord, void* contextRecord, char* buffer, size_t bufferSize);
 716 
 717   // Get the default path to the core file
 718   // Returns the length of the string
 719   static int get_core_path(char* buffer, size_t bufferSize);
 720 
 721   // JVMTI & JVM monitoring and management support
 722   // The thread_cpu_time() and current_thread_cpu_time() are only
 723   // supported if is_thread_cpu_time_supported() returns true.
 724   // They are not supported on Solaris T1.
 725 
 726   // Thread CPU Time - return the fast estimate on a platform
 727   // On Solaris - call gethrvtime (fast) - user time only
 728   // On Linux   - fast clock_gettime where available - user+sys
 729   //            - otherwise: very slow /proc fs - user+sys
 730   // On Windows - GetThreadTimes - user+sys
 731   static jlong current_thread_cpu_time();
 732   static jlong thread_cpu_time(Thread* t);
 733 
 734   // Thread CPU Time with user_sys_cpu_time parameter.
 735   //
 736   // If user_sys_cpu_time is true, user+sys time is returned.
 737   // Otherwise, only user time is returned
 738   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 739   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 740 
 741   // Return a bunch of info about the timers.
 742   // Note that the returned info for these two functions may be different
 743   // on some platforms
 744   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 745   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 746 
 747   static bool is_thread_cpu_time_supported();
 748 
 749   // System loadavg support.  Returns -1 if load average cannot be obtained.
 750   static int loadavg(double loadavg[], int nelem);
 751 
 752   // Hook for os specific jvm options that we don't want to abort on seeing
 753   static bool obsolete_option(const JavaVMOption *option);
 754 
 755   // Extensions
 756 #include "runtime/os_ext.hpp"
 757 
 758  public:
 759   class CrashProtectionCallback : public StackObj {
 760   public:
 761     virtual void call() = 0;
 762   };
 763 
 764   // Platform dependent stuff
 765 #ifdef TARGET_OS_FAMILY_linux
 766 # include "os_linux.hpp"
 767 # include "os_posix.hpp"
 768 #endif
 769 #ifdef TARGET_OS_FAMILY_solaris
 770 # include "os_solaris.hpp"
 771 # include "os_posix.hpp"
 772 #endif
 773 #ifdef TARGET_OS_FAMILY_windows
 774 # include "os_windows.hpp"
 775 #endif
 776 #ifdef TARGET_OS_FAMILY_bsd
 777 # include "os_posix.hpp"
 778 # include "os_bsd.hpp"
 779 #endif
 780 #ifdef TARGET_OS_ARCH_linux_x86
 781 # include "os_linux_x86.hpp"
 782 #endif
 783 #ifdef TARGET_OS_ARCH_linux_sparc
 784 # include "os_linux_sparc.hpp"
 785 #endif
 786 #ifdef TARGET_OS_ARCH_linux_zero
 787 # include "os_linux_zero.hpp"
 788 #endif
 789 #ifdef TARGET_OS_ARCH_solaris_x86
 790 # include "os_solaris_x86.hpp"
 791 #endif
 792 #ifdef TARGET_OS_ARCH_solaris_sparc
 793 # include "os_solaris_sparc.hpp"
 794 #endif
 795 #ifdef TARGET_OS_ARCH_windows_x86
 796 # include "os_windows_x86.hpp"
 797 #endif
 798 #ifdef TARGET_OS_ARCH_linux_arm
 799 # include "os_linux_arm.hpp"
 800 #endif
 801 #ifdef TARGET_OS_ARCH_linux_ppc
 802 # include "os_linux_ppc.hpp"
 803 #endif
 804 #ifdef TARGET_OS_ARCH_bsd_x86
 805 # include "os_bsd_x86.hpp"
 806 #endif
 807 #ifdef TARGET_OS_ARCH_bsd_zero
 808 # include "os_bsd_zero.hpp"
 809 #endif
 810 
 811 #ifndef OS_NATIVE_THREAD_CREATION_FAILED_MSG
 812 #define OS_NATIVE_THREAD_CREATION_FAILED_MSG "unable to create native thread: possibly out of memory or process/resource limits reached"
 813 #endif
 814 
 815  public:
 816 #ifndef PLATFORM_PRINT_NATIVE_STACK
 817   // No platform-specific code for printing the native stack.
 818   static bool platform_print_native_stack(outputStream* st, void* context,
 819                                           char *buf, int buf_size) {
 820     return false;
 821   }
 822 #endif
 823 
 824   // debugging support (mostly used by debug.cpp but also fatal error handler)
 825   static bool find(address pc, outputStream* st = tty); // OS specific function to make sense out of an address
 826 
 827   static bool dont_yield();                     // when true, JVM_Yield() is nop
 828   static void print_statistics();
 829 
 830   // Thread priority helpers (implemented in OS-specific part)
 831   static OSReturn set_native_priority(Thread* thread, int native_prio);
 832   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 833   static int java_to_os_priority[CriticalPriority + 1];
 834   // Hint to the underlying OS that a task switch would not be good.
 835   // Void return because it's a hint and can fail.
 836   static void hint_no_preempt();
 837   static const char* native_thread_creation_failed_msg() {
 838     return OS_NATIVE_THREAD_CREATION_FAILED_MSG;
 839   }
 840 
 841   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 842   // Causes the VM to wait until an external stimulus has been applied
 843   // (for Unix, that stimulus is a signal, for Windows, an external
 844   // ResumeThread call)
 845   static void pause();
 846 
 847   // Builds a platform dependent Agent_OnLoad_<libname> function name
 848   // which is used to find statically linked in agents.
 849   static char*  build_agent_function_name(const char *sym, const char *cname,
 850                                           bool is_absolute_path);
 851 
 852   class SuspendedThreadTaskContext {
 853   public:
 854     SuspendedThreadTaskContext(Thread* thread, void *ucontext) : _thread(thread), _ucontext(ucontext) {}
 855     Thread* thread() const { return _thread; }
 856     void* ucontext() const { return _ucontext; }
 857   private:
 858     Thread* _thread;
 859     void* _ucontext;
 860   };
 861 
 862   class SuspendedThreadTask {
 863   public:
 864     SuspendedThreadTask(Thread* thread) : _thread(thread), _done(false) {}
 865     virtual ~SuspendedThreadTask() {}
 866     void run();
 867     bool is_done() { return _done; }
 868     virtual void do_task(const SuspendedThreadTaskContext& context) = 0;
 869   protected:
 870   private:
 871     void internal_do_task();
 872     Thread* _thread;
 873     bool _done;
 874   };
 875 
 876 #ifndef TARGET_OS_FAMILY_windows
 877   // Suspend/resume support
 878   // Protocol:
 879   //
 880   // a thread starts in SR_RUNNING
 881   //
 882   // SR_RUNNING can go to
 883   //   * SR_SUSPEND_REQUEST when the WatcherThread wants to suspend it
 884   // SR_SUSPEND_REQUEST can go to
 885   //   * SR_RUNNING if WatcherThread decides it waited for SR_SUSPENDED too long (timeout)
 886   //   * SR_SUSPENDED if the stopped thread receives the signal and switches state
 887   // SR_SUSPENDED can go to
 888   //   * SR_WAKEUP_REQUEST when the WatcherThread has done the work and wants to resume
 889   // SR_WAKEUP_REQUEST can go to
 890   //   * SR_RUNNING when the stopped thread receives the signal
 891   //   * SR_WAKEUP_REQUEST on timeout (resend the signal and try again)
 892   class SuspendResume {
 893    public:
 894     enum State {
 895       SR_RUNNING,
 896       SR_SUSPEND_REQUEST,
 897       SR_SUSPENDED,
 898       SR_WAKEUP_REQUEST
 899     };
 900 
 901   private:
 902     volatile State _state;
 903 
 904   private:
 905     /* try to switch state from state "from" to state "to"
 906      * returns the state set after the method is complete
 907      */
 908     State switch_state(State from, State to);
 909 
 910   public:
 911     SuspendResume() : _state(SR_RUNNING) { }
 912 
 913     State state() const { return _state; }
 914 
 915     State request_suspend() {
 916       return switch_state(SR_RUNNING, SR_SUSPEND_REQUEST);
 917     }
 918 
 919     State cancel_suspend() {
 920       return switch_state(SR_SUSPEND_REQUEST, SR_RUNNING);
 921     }
 922 
 923     State suspended() {
 924       return switch_state(SR_SUSPEND_REQUEST, SR_SUSPENDED);
 925     }
 926 
 927     State request_wakeup() {
 928       return switch_state(SR_SUSPENDED, SR_WAKEUP_REQUEST);
 929     }
 930 
 931     State running() {
 932       return switch_state(SR_WAKEUP_REQUEST, SR_RUNNING);
 933     }
 934 
 935     bool is_running() const {
 936       return _state == SR_RUNNING;
 937     }
 938 
 939     bool is_suspend_request() const {
 940       return _state == SR_SUSPEND_REQUEST;
 941     }
 942 
 943     bool is_suspended() const {
 944       return _state == SR_SUSPENDED;
 945     }
 946   };
 947 #endif
 948 
 949 
 950  protected:
 951   static long _rand_seed;                   // seed for random number generator
 952   static int _processor_count;              // number of processors
 953 
 954   static char* format_boot_path(const char* format_string,
 955                                 const char* home,
 956                                 int home_len,
 957                                 char fileSep,
 958                                 char pathSep);
 959   static bool set_boot_path(char fileSep, char pathSep);
 960   static char** split_path(const char* path, int* n);
 961 
 962 };
 963 
 964 // Note that "PAUSE" is almost always used with synchronization
 965 // so arguably we should provide Atomic::SpinPause() instead
 966 // of the global SpinPause() with C linkage.
 967 // It'd also be eligible for inlining on many platforms.
 968 
 969 extern "C" int SpinPause();
 970 
 971 #endif // SHARE_VM_RUNTIME_OS_HPP