1 /*
   2  * Copyright (c) 1997, 2014, 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_aix
  45 # include "jvm_aix.h"
  46 # include <setjmp.h>
  47 #endif
  48 #ifdef TARGET_OS_FAMILY_bsd
  49 # include "jvm_bsd.h"
  50 # include <setjmp.h>
  51 #endif
  52 
  53 class AgentLibrary;
  54 
  55 // os defines the interface to operating system; this includes traditional
  56 // OS services (time, I/O) as well as other functionality with system-
  57 // dependent code.
  58 
  59 typedef void (*dll_func)(...);
  60 
  61 class Thread;
  62 class JavaThread;
  63 class Event;
  64 class DLL;
  65 class FileHandle;
  66 template<class E> class GrowableArray;
  67 
  68 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  69 
  70 // Platform-independent error return values from OS functions
  71 enum OSReturn {
  72   OS_OK         =  0,        // Operation was successful
  73   OS_ERR        = -1,        // Operation failed
  74   OS_INTRPT     = -2,        // Operation was interrupted
  75   OS_TIMEOUT    = -3,        // Operation timed out
  76   OS_NOMEM      = -5,        // Operation failed for lack of memory
  77   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  78 };
  79 
  80 enum ThreadPriority {        // JLS 20.20.1-3
  81   NoPriority       = -1,     // Initial non-priority value
  82   MinPriority      =  1,     // Minimum priority
  83   NormPriority     =  5,     // Normal (non-daemon) priority
  84   NearMaxPriority  =  9,     // High priority, used for VMThread
  85   MaxPriority      = 10,     // Highest priority, used for WatcherThread
  86                              // ensures that VMThread doesn't starve profiler
  87   CriticalPriority = 11      // Critical thread priority
  88 };
  89 
  90 // Executable parameter flag for os::commit_memory() and
  91 // os::commit_memory_or_exit().
  92 const bool ExecMem = true;
  93 
  94 // Typedef for structured exception handling support
  95 typedef void (*java_call_t)(JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
  96 
  97 class os: AllStatic {
  98   friend class VMStructs;
  99 
 100  public:
 101   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
 102 
 103  private:
 104   static OSThread*          _starting_thread;
 105   static address            _polling_page;
 106   static volatile int32_t * _mem_serialize_page;
 107   static uintptr_t          _serialize_page_mask;
 108  public:
 109   static size_t             _page_sizes[page_sizes_max];
 110 
 111  private:
 112   static void init_page_sizes(size_t default_page_size) {
 113     _page_sizes[0] = default_page_size;
 114     _page_sizes[1] = 0; // sentinel
 115   }
 116 
 117   static char*  pd_reserve_memory(size_t bytes, char* addr = 0,
 118                                size_t alignment_hint = 0);
 119   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr);
 120   static void   pd_split_reserved_memory(char *base, size_t size,
 121                                       size_t split, bool realloc);
 122   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
 123   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
 124                                  bool executable);
 125   // Same as pd_commit_memory() that either succeeds or calls
 126   // vm_exit_out_of_memory() with the specified mesg.
 127   static void   pd_commit_memory_or_exit(char* addr, size_t bytes,
 128                                          bool executable, const char* mesg);
 129   static void   pd_commit_memory_or_exit(char* addr, size_t size,
 130                                          size_t alignment_hint,
 131                                          bool executable, const char* mesg);
 132   static bool   pd_uncommit_memory(char* addr, size_t bytes);
 133   static bool   pd_release_memory(char* addr, size_t bytes);
 134 
 135   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
 136                            char *addr, size_t bytes, bool read_only = false,
 137                            bool allow_exec = false);
 138   static char*  pd_remap_memory(int fd, const char* file_name, size_t file_offset,
 139                              char *addr, size_t bytes, bool read_only,
 140                              bool allow_exec);
 141   static bool   pd_unmap_memory(char *addr, size_t bytes);
 142   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
 143   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 144 
 145 
 146  public:
 147   static void init(void);                      // Called before command line parsing
 148   static void init_before_ergo(void);          // Called after command line parsing
 149                                                // before VM ergonomics processing.
 150   static jint init_2(void);                    // Called after command line parsing
 151                                                // and VM ergonomics processing
 152   static void init_globals(void) {             // Called from init_globals() in init.cpp
 153     init_globals_ext();
 154   }
 155   static void init_3(void);                    // Called at the end of vm init
 156 
 157   // File names are case-insensitive on windows only
 158   // Override me as needed
 159   static int    file_name_strcmp(const char* s1, const char* s2);
 160 
 161   static bool getenv(const char* name, char* buffer, int len);
 162   static bool have_special_privileges();
 163 
 164   static jlong  javaTimeMillis();
 165   static jlong  javaTimeNanos();
 166   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
 167   static void   run_periodic_checks();
 168   static bool   supports_monotonic_clock();
 169 
 170 
 171   // Returns the elapsed time in seconds since the vm started.
 172   static double elapsedTime();
 173 
 174   // Returns real time in seconds since an arbitrary point
 175   // in the past.
 176   static bool getTimesSecs(double* process_real_time,
 177                            double* process_user_time,
 178                            double* process_system_time);
 179 
 180   // Interface to the performance counter
 181   static jlong elapsed_counter();
 182   static jlong elapsed_frequency();
 183 
 184   // The "virtual time" of a thread is the amount of time a thread has
 185   // actually run.  The first function indicates whether the OS supports
 186   // this functionality for the current thread, and if so:
 187   //   * the second enables vtime tracking (if that is required).
 188   //   * the third tells whether vtime is enabled.
 189   //   * the fourth returns the elapsed virtual time for the current
 190   //     thread.
 191   static bool supports_vtime();
 192   static bool enable_vtime();
 193   static bool vtime_enabled();
 194   static double elapsedVTime();
 195 
 196   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 197   // It is MT safe, but not async-safe, as reading time zone
 198   // information may require a lock on some platforms.
 199   static char*      local_time_string(char *buf, size_t buflen);
 200   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 201   // Fill in buffer with current local time as an ISO-8601 string.
 202   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 203   // Returns buffer, or NULL if it failed.
 204   static char* iso8601_time(char* buffer, size_t buffer_length);
 205 
 206   // Interface for detecting multiprocessor system
 207   static inline bool is_MP() {
 208     assert(_processor_count > 0, "invalid processor count");
 209     return _processor_count > 1 || AssumeMP;
 210   }
 211   static julong available_memory();
 212   static julong physical_memory();
 213   static bool has_allocatable_memory_limit(julong* limit);
 214   static bool is_server_class_machine();
 215 
 216   // number of CPUs
 217   static int processor_count() {
 218     return _processor_count;
 219   }
 220   static void set_processor_count(int count) { _processor_count = count; }
 221 
 222   // Returns the number of CPUs this process is currently allowed to run on.
 223   // Note that on some OSes this can change dynamically.
 224   static int active_processor_count();
 225 
 226   // Bind processes to processors.
 227   //     This is a two step procedure:
 228   //     first you generate a distribution of processes to processors,
 229   //     then you bind processes according to that distribution.
 230   // Compute a distribution for number of processes to processors.
 231   //    Stores the processor id's into the distribution array argument.
 232   //    Returns true if it worked, false if it didn't.
 233   static bool distribute_processes(uint length, uint* distribution);
 234   // Binds the current process to a processor.
 235   //    Returns true if it worked, false if it didn't.
 236   static bool bind_to_processor(uint processor_id);
 237 
 238   // Give a name to the current thread.
 239   static void set_native_thread_name(const char *name);
 240 
 241   // Interface for stack banging (predetect possible stack overflow for
 242   // exception processing)  There are guard pages, and above that shadow
 243   // pages for stack overflow checking.
 244   static bool uses_stack_guard_pages();
 245   static bool allocate_stack_guard_pages();
 246   static void bang_stack_shadow_pages();
 247   static bool stack_shadow_pages_available(Thread *thread, methodHandle method);
 248 
 249   // OS interface to Virtual Memory
 250 
 251   // Return the default page size.
 252   static int    vm_page_size();
 253 
 254   // Return the page size to use for a region of memory.  The min_pages argument
 255   // is a hint intended to limit fragmentation; it says the returned page size
 256   // should be <= region_max_size / min_pages.  Because min_pages is a hint,
 257   // this routine may return a size larger than region_max_size / min_pages.
 258   //
 259   // The current implementation ignores min_pages if a larger page size is an
 260   // exact multiple of both region_min_size and region_max_size.  This allows
 261   // larger pages to be used when doing so would not cause fragmentation; in
 262   // particular, a single page can be used when region_min_size ==
 263   // region_max_size == a supported page size.
 264   static size_t page_size_for_region(size_t region_min_size,
 265                                      size_t region_max_size,
 266                                      uint min_pages);
 267   // Return the largest page size that can be used
 268   static size_t max_page_size() {
 269     // The _page_sizes array is sorted in descending order.
 270     return _page_sizes[0];
 271   }
 272 
 273   // Methods for tracing page sizes returned by the above method; enabled by
 274   // TracePageSizes.  The region_{min,max}_size parameters should be the values
 275   // passed to page_size_for_region() and page_size should be the result of that
 276   // call.  The (optional) base and size parameters should come from the
 277   // ReservedSpace base() and size() methods.
 278   static void trace_page_sizes(const char* str, const size_t* page_sizes,
 279                                int count) PRODUCT_RETURN;
 280   static void trace_page_sizes(const char* str, const size_t region_min_size,
 281                                const size_t region_max_size,
 282                                const size_t page_size,
 283                                const char* base = NULL,
 284                                const size_t size = 0) PRODUCT_RETURN;
 285 
 286   static int    vm_allocation_granularity();
 287   static char*  reserve_memory(size_t bytes, char* addr = 0,
 288                                size_t alignment_hint = 0);
 289   static char*  reserve_memory(size_t bytes, char* addr,
 290                                size_t alignment_hint, MEMFLAGS flags);
 291   static char*  reserve_memory_aligned(size_t size, size_t alignment);
 292   static char*  attempt_reserve_memory_at(size_t bytes, char* addr);
 293   static void   split_reserved_memory(char *base, size_t size,
 294                                       size_t split, bool realloc);
 295   static bool   commit_memory(char* addr, size_t bytes, bool executable);
 296   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 297                               bool executable);
 298   // Same as commit_memory() that either succeeds or calls
 299   // vm_exit_out_of_memory() with the specified mesg.
 300   static void   commit_memory_or_exit(char* addr, size_t bytes,
 301                                       bool executable, const char* mesg);
 302   static void   commit_memory_or_exit(char* addr, size_t size,
 303                                       size_t alignment_hint,
 304                                       bool executable, const char* mesg);
 305   static bool   uncommit_memory(char* addr, size_t bytes);
 306   static bool   release_memory(char* addr, size_t bytes);
 307 
 308   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 309   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 310                                bool is_committed = true);
 311 
 312   static bool   guard_memory(char* addr, size_t bytes);
 313   static bool   unguard_memory(char* addr, size_t bytes);
 314   static bool   create_stack_guard_pages(char* addr, size_t bytes);
 315   static bool   pd_create_stack_guard_pages(char* addr, size_t bytes);
 316   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
 317 
 318   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 319                            char *addr, size_t bytes, bool read_only = false,
 320                            bool allow_exec = false);
 321   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 322                              char *addr, size_t bytes, bool read_only,
 323                              bool allow_exec);
 324   static bool   unmap_memory(char *addr, size_t bytes);
 325   static void   free_memory(char *addr, size_t bytes, size_t alignment_hint);
 326   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 327 
 328   // NUMA-specific interface
 329   static bool   numa_has_static_binding();
 330   static bool   numa_has_group_homing();
 331   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 332   static void   numa_make_global(char *addr, size_t bytes);
 333   static size_t numa_get_groups_num();
 334   static size_t numa_get_leaf_groups(int *ids, size_t size);
 335   static bool   numa_topology_changed();
 336   static int    numa_get_group_id();
 337 
 338   // Page manipulation
 339   struct page_info {
 340     size_t size;
 341     int lgrp_id;
 342   };
 343   static bool   get_page_info(char *start, page_info* info);
 344   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 345 
 346   static char*  non_memory_address_word();
 347   // reserve, commit and pin the entire memory region
 348   static char*  reserve_memory_special(size_t size, size_t alignment,
 349                                        char* addr, bool executable);
 350   static bool   release_memory_special(char* addr, size_t bytes);
 351   static void   large_page_init();
 352   static size_t large_page_size();
 353   static bool   can_commit_large_page_memory();
 354   static bool   can_execute_large_page_memory();
 355 
 356   // OS interface to polling page
 357   static address get_polling_page()             { return _polling_page; }
 358   static void    set_polling_page(address page) { _polling_page = page; }
 359   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 360   static void    make_polling_page_unreadable();
 361   static void    make_polling_page_readable();
 362 
 363   // Routines used to serialize the thread state without using membars
 364   static void    serialize_thread_states();
 365 
 366   // Since we write to the serialize page from every thread, we
 367   // want stores to be on unique cache lines whenever possible
 368   // in order to minimize CPU cross talk.  We pre-compute the
 369   // amount to shift the thread* to make this offset unique to
 370   // each thread.
 371   static int     get_serialize_page_shift_count() {
 372     return SerializePageShiftCount;
 373   }
 374 
 375   static void     set_serialize_page_mask(uintptr_t mask) {
 376     _serialize_page_mask = mask;
 377   }
 378 
 379   static unsigned int  get_serialize_page_mask() {
 380     return _serialize_page_mask;
 381   }
 382 
 383   static void    set_memory_serialize_page(address page);
 384 
 385   static address get_memory_serialize_page() {
 386     return (address)_mem_serialize_page;
 387   }
 388 
 389   static inline void write_memory_serialize_page(JavaThread *thread) {
 390     uintptr_t page_offset = ((uintptr_t)thread >>
 391                             get_serialize_page_shift_count()) &
 392                             get_serialize_page_mask();
 393     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
 394   }
 395 
 396   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
 397     if (UseMembar) return false;
 398     // Previously this function calculated the exact address of this
 399     // thread's serialize page, and checked if the faulting address
 400     // was equal.  However, some platforms mask off faulting addresses
 401     // to the page size, so now we just check that the address is
 402     // within the page.  This makes the thread argument unnecessary,
 403     // but we retain the NULL check to preserve existing behavior.
 404     if (thread == NULL) return false;
 405     address page = (address) _mem_serialize_page;
 406     return addr >= page && addr < (page + os::vm_page_size());
 407   }
 408 
 409   static void block_on_serialize_page_trap();
 410 
 411   // threads
 412 
 413   enum ThreadType {
 414     vm_thread,
 415     cgc_thread,        // Concurrent GC thread
 416     pgc_thread,        // Parallel GC thread
 417     java_thread,
 418     compiler_thread,
 419     watcher_thread,
 420     os_thread
 421   };
 422 
 423   static bool create_thread(Thread* thread,
 424                             ThreadType thr_type,
 425                             size_t stack_size = 0);
 426   static bool create_main_thread(JavaThread* thread);
 427   static bool create_attached_thread(JavaThread* thread);
 428   static void pd_start_thread(Thread* thread);
 429   static void start_thread(Thread* thread);
 430 
 431   static void initialize_thread(Thread* thr);
 432   static void free_thread(OSThread* osthread);
 433 
 434   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 435   static intx current_thread_id();
 436   static int current_process_id();
 437   static int sleep(Thread* thread, jlong ms, bool interruptable);
 438   // Short standalone OS sleep suitable for slow path spin loop.
 439   // Ignores Thread.interrupt() (so keep it short).
 440   // ms = 0, will sleep for the least amount of time allowed by the OS.
 441   static void naked_short_sleep(jlong ms);
 442   static void infinite_sleep(); // never returns, use with CAUTION
 443   static void yield();        // Yields to all threads with same priority
 444   enum YieldResult {
 445     YIELD_SWITCHED = 1,         // caller descheduled, other ready threads exist & ran
 446     YIELD_NONEREADY = 0,        // No other runnable/ready threads.
 447                                 // platform-specific yield return immediately
 448     YIELD_UNKNOWN = -1          // Unknown: platform doesn't support _SWITCHED or _NONEREADY
 449     // YIELD_SWITCHED and YIELD_NONREADY imply the platform supports a "strong"
 450     // yield that can be used in lieu of blocking.
 451   } ;
 452   static YieldResult NakedYield () ;
 453   static void yield_all(); // Yields to all other threads including lower priority
 454                            // (for the default scheduling policy)
 455   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 456   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 457 
 458   static void interrupt(Thread* thread);
 459   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 460 
 461   static int pd_self_suspend_thread(Thread* thread);
 462 
 463   static ExtendedPC fetch_frame_from_context(void* ucVoid, intptr_t** sp, intptr_t** fp);
 464   static frame      fetch_frame_from_context(void* ucVoid);
 465 
 466   static ExtendedPC get_thread_pc(Thread *thread);
 467   static void breakpoint();
 468 
 469   static address current_stack_pointer();
 470   static address current_stack_base();
 471   static size_t current_stack_size();
 472 
 473   static void verify_stack_alignment() PRODUCT_RETURN;
 474 
 475   static int message_box(const char* title, const char* message);
 476   static char* do_you_want_to_debug(const char* message);
 477 
 478   // run cmd in a separate process and return its exit code; or -1 on failures
 479   static int fork_and_exec(char *cmd);
 480 
 481   // Set file to send error reports.
 482   static void set_error_file(const char *logfile);
 483 
 484   // os::exit() is merged with vm_exit()
 485   // static void exit(int num);
 486 
 487   // Terminate the VM, but don't exit the process
 488   static void shutdown();
 489 
 490   // Terminate with an error.  Default is to generate a core file on platforms
 491   // that support such things.  This calls shutdown() and then aborts.
 492   static void abort(bool dump_core = true);
 493 
 494   // Die immediately, no exit hook, no abort hook, no cleanup.
 495   static void die();
 496 
 497   // File i/o operations
 498   static const int default_file_open_flags();
 499   static int open(const char *path, int oflag, int mode);
 500   static FILE* open(int fd, const char* mode);
 501   static int close(int fd);
 502   static jlong lseek(int fd, jlong offset, int whence);
 503   static char* native_path(char *path);
 504   static int ftruncate(int fd, jlong length);
 505   static int fsync(int fd);
 506   static int available(int fd, jlong *bytes);
 507 
 508   //File i/o operations
 509 
 510   static size_t read(int fd, void *buf, unsigned int nBytes);
 511   static size_t restartable_read(int fd, void *buf, unsigned int nBytes);
 512   static size_t write(int fd, const void *buf, unsigned int nBytes);
 513 
 514   // Reading directories.
 515   static DIR*           opendir(const char* dirname);
 516   static int            readdir_buf_size(const char *path);
 517   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
 518   static int            closedir(DIR* dirp);
 519 
 520   // Dynamic library extension
 521   static const char*    dll_file_extension();
 522 
 523   static const char*    get_temp_directory();
 524   static const char*    get_current_directory(char *buf, size_t buflen);
 525 
 526   // Builds a platform-specific full library path given a ld path and lib name
 527   // Returns true if buffer contains full path to existing file, false otherwise
 528   static bool           dll_build_name(char* buffer, size_t size,
 529                                        const char* pathname, const char* fname);
 530 
 531   // Symbol lookup, find nearest function name; basically it implements
 532   // dladdr() for all platforms. Name of the nearest function is copied
 533   // to buf. Distance from its base address is optionally returned as offset.
 534   // If function name is not found, buf[0] is set to '\0' and offset is
 535   // set to -1 (if offset is non-NULL).
 536   static bool dll_address_to_function_name(address addr, char* buf,
 537                                            int buflen, int* offset);
 538 
 539   // Locate DLL/DSO. On success, full path of the library is copied to
 540   // buf, and offset is optionally set to be the distance between addr
 541   // and the library's base address. On failure, buf[0] is set to '\0'
 542   // and offset is set to -1 (if offset is non-NULL).
 543   static bool dll_address_to_library_name(address addr, char* buf,
 544                                           int buflen, int* offset);
 545 
 546   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 547   static bool address_is_in_vm(address addr);
 548 
 549   // Loads .dll/.so and
 550   // in case of error it checks if .dll/.so was built for the
 551   // same architecture as HotSpot is running on
 552   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 553 
 554   // lookup symbol in a shared library
 555   static void* dll_lookup(void* handle, const char* name);
 556 
 557   // Unload library
 558   static void  dll_unload(void *lib);
 559 
 560   // Return the handle of this process
 561   static void* get_default_process_handle();
 562 
 563   // Check for static linked agent library
 564   static bool find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 565                                  size_t syms_len);
 566 
 567   // Find agent entry point
 568   static void *find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 569                                    const char *syms[], size_t syms_len);
 570 
 571   // Print out system information; they are called by fatal error handler.
 572   // Output format may be different on different platforms.
 573   static void print_os_info(outputStream* st);
 574   static void print_os_info_brief(outputStream* st);
 575   static void print_cpu_info(outputStream* st);
 576   static void pd_print_cpu_info(outputStream* st);
 577   static void print_memory_info(outputStream* st);
 578   static void print_dll_info(outputStream* st);
 579   static void print_environment_variables(outputStream* st, const char** env_list, char* buffer, int len);
 580   static void print_context(outputStream* st, void* context);
 581   static void print_register_info(outputStream* st, void* context);
 582   static void print_siginfo(outputStream* st, void* siginfo);
 583   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 584   static void print_date_and_time(outputStream* st);
 585 
 586   static void print_location(outputStream* st, intptr_t x, bool verbose = false);
 587   static size_t lasterror(char *buf, size_t len);
 588   static int get_last_error();
 589 
 590   // Determines whether the calling process is being debugged by a user-mode debugger.
 591   static bool is_debugger_attached();
 592 
 593   // wait for a key press if PauseAtExit is set
 594   static void wait_for_keypress_at_exit(void);
 595 
 596   // The following two functions are used by fatal error handler to trace
 597   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 598   // frame.hpp/cpp assume thread is JavaThread, and also because different
 599   // OS/compiler may have different convention or provide different API to
 600   // walk C frames.
 601   //
 602   // We don't attempt to become a debugger, so we only follow frames if that
 603   // does not require a lookup in the unwind table, which is part of the binary
 604   // file but may be unsafe to read after a fatal error. So on x86, we can
 605   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 606   // possible to walk C stack without having the unwind table.
 607   static bool is_first_C_frame(frame *fr);
 608   static frame get_sender_for_C_frame(frame *fr);
 609 
 610   // return current frame. pc() and sp() are set to NULL on failure.
 611   static frame      current_frame();
 612 
 613   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 614 
 615   // returns a string to describe the exception/signal;
 616   // returns NULL if exception_code is not an OS exception/signal.
 617   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 618 
 619   // Returns native Java library, loads if necessary
 620   static void*    native_java_library();
 621 
 622   // Fills in path to jvm.dll/libjvm.so (used by the Disassembler)
 623   static void     jvm_path(char *buf, jint buflen);
 624 
 625   // Returns true if we are running in a headless jre.
 626   static bool     is_headless_jre();
 627 
 628   // JNI names
 629   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 630   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 631 
 632   // File conventions
 633   static const char* file_separator();
 634   static const char* line_separator();
 635   static const char* path_separator();
 636 
 637   // Init os specific system properties values
 638   static void init_system_properties_values();
 639 
 640   // IO operations, non-JVM_ version.
 641   static int stat(const char* path, struct stat* sbuf);
 642   static bool dir_is_empty(const char* path);
 643 
 644   // IO operations on binary files
 645   static int create_binary_file(const char* path, bool rewrite_existing);
 646   static jlong current_file_offset(int fd);
 647   static jlong seek_to_file_offset(int fd, jlong offset);
 648 
 649   // Thread Local Storage
 650   static int   allocate_thread_local_storage();
 651   static void  thread_local_storage_at_put(int index, void* value);
 652   static void* thread_local_storage_at(int index);
 653   static void  free_thread_local_storage(int index);
 654 
 655   // Stack walk
 656   static address get_caller_pc(int n = 0);
 657 
 658   // General allocation (must be MT-safe)
 659   static void* malloc  (size_t size, MEMFLAGS flags, address caller_pc = 0);
 660   static void* realloc (void *memblock, size_t size, MEMFLAGS flags, address caller_pc = 0);
 661   static void  free    (void *memblock, MEMFLAGS flags = mtNone);
 662   static bool  check_heap(bool force = false);      // verify C heap integrity
 663   static char* strdup(const char *, MEMFLAGS flags = mtInternal);  // Like strdup
 664 
 665 #ifndef PRODUCT
 666   static julong num_mallocs;         // # of calls to malloc/realloc
 667   static julong alloc_bytes;         // # of bytes allocated
 668   static julong num_frees;           // # of calls to free
 669   static julong free_bytes;          // # of bytes freed
 670 #endif
 671 
 672   // SocketInterface (ex HPI SocketInterface )
 673   static int socket(int domain, int type, int protocol);
 674   static int socket_close(int fd);
 675   static int socket_shutdown(int fd, int howto);
 676   static int recv(int fd, char* buf, size_t nBytes, uint flags);
 677   static int send(int fd, char* buf, size_t nBytes, uint flags);
 678   static int raw_send(int fd, char* buf, size_t nBytes, uint flags);
 679   static int timeout(int fd, long timeout);
 680   static int listen(int fd, int count);
 681   static int connect(int fd, struct sockaddr* him, socklen_t len);
 682   static int bind(int fd, struct sockaddr* him, socklen_t len);
 683   static int accept(int fd, struct sockaddr* him, socklen_t* len);
 684   static int recvfrom(int fd, char* buf, size_t nbytes, uint flags,
 685                       struct sockaddr* from, socklen_t* fromlen);
 686   static int get_sock_name(int fd, struct sockaddr* him, socklen_t* len);
 687   static int sendto(int fd, char* buf, size_t len, uint flags,
 688                     struct sockaddr* to, socklen_t tolen);
 689   static int socket_available(int fd, jint* pbytes);
 690 
 691   static int get_sock_opt(int fd, int level, int optname,
 692                           char* optval, socklen_t* optlen);
 693   static int set_sock_opt(int fd, int level, int optname,
 694                           const char* optval, socklen_t optlen);
 695   static int get_host_name(char* name, int namelen);
 696 
 697   static struct hostent* get_host_by_name(char* name);
 698 
 699   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 700   static void  signal_init();
 701   static void  signal_init_pd();
 702   static void  signal_notify(int signal_number);
 703   static void* signal(int signal_number, void* handler);
 704   static void  signal_raise(int signal_number);
 705   static int   signal_wait();
 706   static int   signal_lookup();
 707   static void* user_handler();
 708   static void  terminate_signal_thread();
 709   static int   sigexitnum_pd();
 710 
 711   // random number generation
 712   static long random();                    // return 32bit pseudorandom number
 713   static void init_random(long initval);   // initialize random sequence
 714 
 715   // Structured OS Exception support
 716   static void os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
 717 
 718   // On Windows this will create an actual minidump, on Linux/Solaris it will simply check core dump limits
 719   static void check_or_create_dump(void* exceptionRecord, void* contextRecord, char* buffer, size_t bufferSize);
 720 
 721   // Get the default path to the core file
 722   // Returns the length of the string
 723   static int get_core_path(char* buffer, size_t bufferSize);
 724 
 725   // JVMTI & JVM monitoring and management support
 726   // The thread_cpu_time() and current_thread_cpu_time() are only
 727   // supported if is_thread_cpu_time_supported() returns true.
 728   // They are not supported on Solaris T1.
 729 
 730   // Thread CPU Time - return the fast estimate on a platform
 731   // On Solaris - call gethrvtime (fast) - user time only
 732   // On Linux   - fast clock_gettime where available - user+sys
 733   //            - otherwise: very slow /proc fs - user+sys
 734   // On Windows - GetThreadTimes - user+sys
 735   static jlong current_thread_cpu_time();
 736   static jlong thread_cpu_time(Thread* t);
 737 
 738   // Thread CPU Time with user_sys_cpu_time parameter.
 739   //
 740   // If user_sys_cpu_time is true, user+sys time is returned.
 741   // Otherwise, only user time is returned
 742   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 743   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 744 
 745   // Return a bunch of info about the timers.
 746   // Note that the returned info for these two functions may be different
 747   // on some platforms
 748   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 749   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 750 
 751   static bool is_thread_cpu_time_supported();
 752 
 753   // System loadavg support.  Returns -1 if load average cannot be obtained.
 754   static int loadavg(double loadavg[], int nelem);
 755 
 756   // Hook for os specific jvm options that we don't want to abort on seeing
 757   static bool obsolete_option(const JavaVMOption *option);
 758 
 759   // Extensions
 760 #include "runtime/os_ext.hpp"
 761 
 762  public:
 763   class CrashProtectionCallback : public StackObj {
 764   public:
 765     virtual void call() = 0;
 766   };
 767 
 768   // Platform dependent stuff
 769 #ifdef TARGET_OS_FAMILY_linux
 770 # include "os_linux.hpp"
 771 # include "os_posix.hpp"
 772 #endif
 773 #ifdef TARGET_OS_FAMILY_solaris
 774 # include "os_solaris.hpp"
 775 # include "os_posix.hpp"
 776 #endif
 777 #ifdef TARGET_OS_FAMILY_windows
 778 # include "os_windows.hpp"
 779 #endif
 780 #ifdef TARGET_OS_FAMILY_aix
 781 # include "os_aix.hpp"
 782 # include "os_posix.hpp"
 783 #endif
 784 #ifdef TARGET_OS_FAMILY_bsd
 785 # include "os_posix.hpp"
 786 # include "os_bsd.hpp"
 787 #endif
 788 #ifdef TARGET_OS_ARCH_linux_x86
 789 # include "os_linux_x86.hpp"
 790 #endif
 791 #ifdef TARGET_OS_ARCH_linux_sparc
 792 # include "os_linux_sparc.hpp"
 793 #endif
 794 #ifdef TARGET_OS_ARCH_linux_zero
 795 # include "os_linux_zero.hpp"
 796 #endif
 797 #ifdef TARGET_OS_ARCH_solaris_x86
 798 # include "os_solaris_x86.hpp"
 799 #endif
 800 #ifdef TARGET_OS_ARCH_solaris_sparc
 801 # include "os_solaris_sparc.hpp"
 802 #endif
 803 #ifdef TARGET_OS_ARCH_windows_x86
 804 # include "os_windows_x86.hpp"
 805 #endif
 806 #ifdef TARGET_OS_ARCH_linux_arm
 807 # include "os_linux_arm.hpp"
 808 #endif
 809 #ifdef TARGET_OS_ARCH_linux_ppc
 810 # include "os_linux_ppc.hpp"
 811 #endif
 812 #ifdef TARGET_OS_ARCH_aix_ppc
 813 # include "os_aix_ppc.hpp"
 814 #endif
 815 #ifdef TARGET_OS_ARCH_bsd_x86
 816 # include "os_bsd_x86.hpp"
 817 #endif
 818 #ifdef TARGET_OS_ARCH_bsd_zero
 819 # include "os_bsd_zero.hpp"
 820 #endif
 821 
 822 #ifndef OS_NATIVE_THREAD_CREATION_FAILED_MSG
 823 #define OS_NATIVE_THREAD_CREATION_FAILED_MSG "unable to create native thread: possibly out of memory or process/resource limits reached"
 824 #endif
 825 
 826  public:
 827 #ifndef PLATFORM_PRINT_NATIVE_STACK
 828   // No platform-specific code for printing the native stack.
 829   static bool platform_print_native_stack(outputStream* st, void* context,
 830                                           char *buf, int buf_size) {
 831     return false;
 832   }
 833 #endif
 834 
 835   // debugging support (mostly used by debug.cpp but also fatal error handler)
 836   static bool find(address pc, outputStream* st = tty); // OS specific function to make sense out of an address
 837 
 838   static bool dont_yield();                     // when true, JVM_Yield() is nop
 839   static void print_statistics();
 840 
 841   // Thread priority helpers (implemented in OS-specific part)
 842   static OSReturn set_native_priority(Thread* thread, int native_prio);
 843   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 844   static int java_to_os_priority[CriticalPriority + 1];
 845   // Hint to the underlying OS that a task switch would not be good.
 846   // Void return because it's a hint and can fail.
 847   static void hint_no_preempt();
 848   static const char* native_thread_creation_failed_msg() {
 849     return OS_NATIVE_THREAD_CREATION_FAILED_MSG;
 850   }
 851 
 852   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 853   // Causes the VM to wait until an external stimulus has been applied
 854   // (for Unix, that stimulus is a signal, for Windows, an external
 855   // ResumeThread call)
 856   static void pause();
 857 
 858   // Builds a platform dependent Agent_OnLoad_<libname> function name
 859   // which is used to find statically linked in agents.
 860   static char*  build_agent_function_name(const char *sym, const char *cname,
 861                                           bool is_absolute_path);
 862 
 863   class SuspendedThreadTaskContext {
 864   public:
 865     SuspendedThreadTaskContext(Thread* thread, void *ucontext) : _thread(thread), _ucontext(ucontext) {}
 866     Thread* thread() const { return _thread; }
 867     void* ucontext() const { return _ucontext; }
 868   private:
 869     Thread* _thread;
 870     void* _ucontext;
 871   };
 872 
 873   class SuspendedThreadTask {
 874   public:
 875     SuspendedThreadTask(Thread* thread) : _thread(thread), _done(false) {}
 876     virtual ~SuspendedThreadTask() {}
 877     void run();
 878     bool is_done() { return _done; }
 879     virtual void do_task(const SuspendedThreadTaskContext& context) = 0;
 880   protected:
 881   private:
 882     void internal_do_task();
 883     Thread* _thread;
 884     bool _done;
 885   };
 886 
 887 #ifndef TARGET_OS_FAMILY_windows
 888   // Suspend/resume support
 889   // Protocol:
 890   //
 891   // a thread starts in SR_RUNNING
 892   //
 893   // SR_RUNNING can go to
 894   //   * SR_SUSPEND_REQUEST when the WatcherThread wants to suspend it
 895   // SR_SUSPEND_REQUEST can go to
 896   //   * SR_RUNNING if WatcherThread decides it waited for SR_SUSPENDED too long (timeout)
 897   //   * SR_SUSPENDED if the stopped thread receives the signal and switches state
 898   // SR_SUSPENDED can go to
 899   //   * SR_WAKEUP_REQUEST when the WatcherThread has done the work and wants to resume
 900   // SR_WAKEUP_REQUEST can go to
 901   //   * SR_RUNNING when the stopped thread receives the signal
 902   //   * SR_WAKEUP_REQUEST on timeout (resend the signal and try again)
 903   class SuspendResume {
 904    public:
 905     enum State {
 906       SR_RUNNING,
 907       SR_SUSPEND_REQUEST,
 908       SR_SUSPENDED,
 909       SR_WAKEUP_REQUEST
 910     };
 911 
 912   private:
 913     volatile State _state;
 914 
 915   private:
 916     /* try to switch state from state "from" to state "to"
 917      * returns the state set after the method is complete
 918      */
 919     State switch_state(State from, State to);
 920 
 921   public:
 922     SuspendResume() : _state(SR_RUNNING) { }
 923 
 924     State state() const { return _state; }
 925 
 926     State request_suspend() {
 927       return switch_state(SR_RUNNING, SR_SUSPEND_REQUEST);
 928     }
 929 
 930     State cancel_suspend() {
 931       return switch_state(SR_SUSPEND_REQUEST, SR_RUNNING);
 932     }
 933 
 934     State suspended() {
 935       return switch_state(SR_SUSPEND_REQUEST, SR_SUSPENDED);
 936     }
 937 
 938     State request_wakeup() {
 939       return switch_state(SR_SUSPENDED, SR_WAKEUP_REQUEST);
 940     }
 941 
 942     State running() {
 943       return switch_state(SR_WAKEUP_REQUEST, SR_RUNNING);
 944     }
 945 
 946     bool is_running() const {
 947       return _state == SR_RUNNING;
 948     }
 949 
 950     bool is_suspend_request() const {
 951       return _state == SR_SUSPEND_REQUEST;
 952     }
 953 
 954     bool is_suspended() const {
 955       return _state == SR_SUSPENDED;
 956     }
 957   };
 958 #endif
 959 
 960 
 961  protected:
 962   static long _rand_seed;                   // seed for random number generator
 963   static int _processor_count;              // number of processors
 964 
 965   static char* format_boot_path(const char* format_string,
 966                                 const char* home,
 967                                 int home_len,
 968                                 char fileSep,
 969                                 char pathSep);
 970   static bool set_boot_path(char fileSep, char pathSep);
 971   static char** split_path(const char* path, int* n);
 972 
 973 };
 974 
 975 // Note that "PAUSE" is almost always used with synchronization
 976 // so arguably we should provide Atomic::SpinPause() instead
 977 // of the global SpinPause() with C linkage.
 978 // It'd also be eligible for inlining on many platforms.
 979 
 980 extern "C" int SpinPause();
 981 
 982 #endif // SHARE_VM_RUNTIME_OS_HPP