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