1 /*
   2  * Copyright (c) 1997, 2019, 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_RUNTIME_OS_HPP
  26 #define SHARE_RUNTIME_OS_HPP
  27 
  28 #include "jvm.h"
  29 #include "jvmtifiles/jvmti.h"
  30 #include "metaprogramming/isRegisteredEnum.hpp"
  31 #include "metaprogramming/integralConstant.hpp"
  32 #include "runtime/extendedPC.hpp"
  33 #include "utilities/exceptions.hpp"
  34 #include "utilities/ostream.hpp"
  35 #include "utilities/macros.hpp"
  36 #ifndef _WINDOWS
  37 # include <setjmp.h>
  38 #endif
  39 #ifdef __APPLE__
  40 # include <mach/mach_time.h>
  41 #endif
  42 
  43 class AgentLibrary;
  44 class frame;
  45 
  46 // os defines the interface to operating system; this includes traditional
  47 // OS services (time, I/O) as well as other functionality with system-
  48 // dependent code.
  49 
  50 typedef void (*dll_func)(...);
  51 
  52 class Thread;
  53 class JavaThread;
  54 class NativeCallStack;
  55 class methodHandle;
  56 class OSThread;
  57 class Mutex;
  58 
  59 template<class E> class GrowableArray;
  60 
  61 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  62 
  63 // Platform-independent error return values from OS functions
  64 enum OSReturn {
  65   OS_OK         =  0,        // Operation was successful
  66   OS_ERR        = -1,        // Operation failed
  67   OS_INTRPT     = -2,        // Operation was interrupted
  68   OS_TIMEOUT    = -3,        // Operation timed out
  69   OS_NOMEM      = -5,        // Operation failed for lack of memory
  70   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  71 };
  72 
  73 enum ThreadPriority {        // JLS 20.20.1-3
  74   NoPriority       = -1,     // Initial non-priority value
  75   MinPriority      =  1,     // Minimum priority
  76   NormPriority     =  5,     // Normal (non-daemon) priority
  77   NearMaxPriority  =  9,     // High priority, used for VMThread
  78   MaxPriority      = 10,     // Highest priority, used for WatcherThread
  79                              // ensures that VMThread doesn't starve profiler
  80   CriticalPriority = 11      // Critical thread priority
  81 };
  82 
  83 // Executable parameter flag for os::commit_memory() and
  84 // os::commit_memory_or_exit().
  85 const bool ExecMem = true;
  86 
  87 // Typedef for structured exception handling support
  88 typedef void (*java_call_t)(JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread);
  89 
  90 class MallocTracker;
  91 
  92 class os: AllStatic {
  93   friend class VMStructs;
  94   friend class JVMCIVMStructs;
  95   friend class MallocTracker;
  96 
  97 #ifdef ASSERT
  98  private:
  99   static bool _mutex_init_done;
 100  public:
 101   static void set_mutex_init_done() { _mutex_init_done = true; }
 102   static bool mutex_init_done() { return _mutex_init_done; }
 103 #endif
 104 
 105  public:
 106   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
 107 
 108  private:
 109   static OSThread*          _starting_thread;
 110   static address            _polling_page;
 111  public:
 112   static size_t             _page_sizes[page_sizes_max];
 113 
 114  private:
 115   static void init_page_sizes(size_t default_page_size) {
 116     _page_sizes[0] = default_page_size;
 117     _page_sizes[1] = 0; // sentinel
 118   }
 119 
 120   static char*  pd_reserve_memory(size_t bytes, char* addr = 0,
 121                                   size_t alignment_hint = 0);
 122   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr);
 123   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr, int file_desc);
 124   static void   pd_split_reserved_memory(char *base, size_t size,
 125                                       size_t split, bool realloc);
 126   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
 127   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
 128                                  bool executable);
 129   // Same as pd_commit_memory() that either succeeds or calls
 130   // vm_exit_out_of_memory() with the specified mesg.
 131   static void   pd_commit_memory_or_exit(char* addr, size_t bytes,
 132                                          bool executable, const char* mesg);
 133   static void   pd_commit_memory_or_exit(char* addr, size_t size,
 134                                          size_t alignment_hint,
 135                                          bool executable, const char* mesg);
 136   static bool   pd_uncommit_memory(char* addr, size_t bytes);
 137   static bool   pd_release_memory(char* addr, size_t bytes);
 138 
 139   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
 140                            char *addr, size_t bytes, bool read_only = false,
 141                            bool allow_exec = false);
 142   static char*  pd_remap_memory(int fd, const char* file_name, size_t file_offset,
 143                              char *addr, size_t bytes, bool read_only,
 144                              bool allow_exec);
 145   static bool   pd_unmap_memory(char *addr, size_t bytes);
 146   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
 147   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 148 
 149   static size_t page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned);
 150 
 151   // Get summary strings for system information in buffer provided
 152   static void  get_summary_cpu_info(char* buf, size_t buflen);
 153   static void  get_summary_os_info(char* buf, size_t buflen);
 154 
 155   static void initialize_initial_active_processor_count();
 156 
 157   LINUX_ONLY(static void pd_init_container_support();)
 158 
 159  public:
 160   static void init(void);                      // Called before command line parsing
 161 
 162   static void init_container_support() {       // Called during command line parsing.
 163      LINUX_ONLY(pd_init_container_support();)
 164   }
 165 
 166   static void init_before_ergo(void);          // Called after command line parsing
 167                                                // before VM ergonomics processing.
 168   static jint init_2(void);                    // Called after command line parsing
 169                                                // and VM ergonomics processing
 170   static void init_globals(void) {             // Called from init_globals() in init.cpp
 171     init_globals_ext();
 172   }
 173 
 174   // File names are case-insensitive on windows only
 175   // Override me as needed
 176   static int    file_name_strncmp(const char* s1, const char* s2, size_t num);
 177 
 178   // unset environment variable
 179   static bool unsetenv(const char* name);
 180 
 181   static bool have_special_privileges();
 182 
 183   static jlong  javaTimeMillis();
 184   static jlong  javaTimeNanos();
 185   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
 186   static void   javaTimeSystemUTC(jlong &seconds, jlong &nanos);
 187   static void   run_periodic_checks();
 188   static bool   supports_monotonic_clock();
 189 
 190   // Returns the elapsed time in seconds since the vm started.
 191   static double elapsedTime();
 192 
 193   // Returns real time in seconds since an arbitrary point
 194   // in the past.
 195   static bool getTimesSecs(double* process_real_time,
 196                            double* process_user_time,
 197                            double* process_system_time);
 198 
 199   // Interface to the performance counter
 200   static jlong elapsed_counter();
 201   static jlong elapsed_frequency();
 202 
 203   // The "virtual time" of a thread is the amount of time a thread has
 204   // actually run.  The first function indicates whether the OS supports
 205   // this functionality for the current thread, and if so:
 206   //   * the second enables vtime tracking (if that is required).
 207   //   * the third tells whether vtime is enabled.
 208   //   * the fourth returns the elapsed virtual time for the current
 209   //     thread.
 210   static bool supports_vtime();
 211   static bool enable_vtime();
 212   static bool vtime_enabled();
 213   static double elapsedVTime();
 214 
 215   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 216   // It is MT safe, but not async-safe, as reading time zone
 217   // information may require a lock on some platforms.
 218   static char*      local_time_string(char *buf, size_t buflen);
 219   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 220   static struct tm* gmtime_pd        (const time_t* clock, struct tm*  res);
 221   // Fill in buffer with current local time as an ISO-8601 string.
 222   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 223   // Returns buffer, or NULL if it failed.
 224   static char* iso8601_time(char* buffer, size_t buffer_length, bool utc = false);
 225 
 226   // Interface for detecting multiprocessor system
 227   static inline bool is_MP() {
 228     // During bootstrap if _processor_count is not yet initialized
 229     // we claim to be MP as that is safest. If any platform has a
 230     // stub generator that might be triggered in this phase and for
 231     // which being declared MP when in fact not, is a problem - then
 232     // the bootstrap routine for the stub generator needs to check
 233     // the processor count directly and leave the bootstrap routine
 234     // in place until called after initialization has ocurred.
 235     return (_processor_count != 1);
 236   }
 237 
 238   static julong available_memory();
 239   static julong physical_memory();
 240   static bool has_allocatable_memory_limit(julong* limit);
 241   static bool is_server_class_machine();
 242 
 243   // Returns the id of the processor on which the calling thread is currently executing.
 244   // The returned value is guaranteed to be between 0 and (os::processor_count() - 1).
 245   static uint processor_id();
 246 
 247   // number of CPUs
 248   static int processor_count() {
 249     return _processor_count;
 250   }
 251   static void set_processor_count(int count) { _processor_count = count; }
 252 
 253   // Returns the number of CPUs this process is currently allowed to run on.
 254   // Note that on some OSes this can change dynamically.
 255   static int active_processor_count();
 256 
 257   // At startup the number of active CPUs this process is allowed to run on.
 258   // This value does not change dynamically. May be different from active_processor_count().
 259   static int initial_active_processor_count() {
 260     assert(_initial_active_processor_count > 0, "Initial active processor count not set yet.");
 261     return _initial_active_processor_count;
 262   }
 263 
 264   // Bind processes to processors.
 265   //     This is a two step procedure:
 266   //     first you generate a distribution of processes to processors,
 267   //     then you bind processes according to that distribution.
 268   // Compute a distribution for number of processes to processors.
 269   //    Stores the processor id's into the distribution array argument.
 270   //    Returns true if it worked, false if it didn't.
 271   static bool distribute_processes(uint length, uint* distribution);
 272   // Binds the current process to a processor.
 273   //    Returns true if it worked, false if it didn't.
 274   static bool bind_to_processor(uint processor_id);
 275 
 276   // Give a name to the current thread.
 277   static void set_native_thread_name(const char *name);
 278 
 279   // Interface for stack banging (predetect possible stack overflow for
 280   // exception processing)  There are guard pages, and above that shadow
 281   // pages for stack overflow checking.
 282   static bool uses_stack_guard_pages();
 283   static bool must_commit_stack_guard_pages();
 284   static void map_stack_shadow_pages(address sp);
 285   static bool stack_shadow_pages_available(Thread *thread, const methodHandle& method, address sp);
 286 
 287   // Find committed memory region within specified range (start, start + size),
 288   // return true if found any
 289   static bool committed_in_range(address start, size_t size, address& committed_start, size_t& committed_size);
 290 
 291   // OS interface to Virtual Memory
 292 
 293   // Return the default page size.
 294   static int    vm_page_size();
 295 
 296   // Returns the page size to use for a region of memory.
 297   // region_size / min_pages will always be greater than or equal to the
 298   // returned value. The returned value will divide region_size.
 299   static size_t page_size_for_region_aligned(size_t region_size, size_t min_pages);
 300 
 301   // Returns the page size to use for a region of memory.
 302   // region_size / min_pages will always be greater than or equal to the
 303   // returned value. The returned value might not divide region_size.
 304   static size_t page_size_for_region_unaligned(size_t region_size, size_t min_pages);
 305 
 306   // Return the largest page size that can be used
 307   static size_t max_page_size() {
 308     // The _page_sizes array is sorted in descending order.
 309     return _page_sizes[0];
 310   }
 311 
 312   // Return a lower bound for page sizes. Also works before os::init completed.
 313   static size_t min_page_size() { return 4 * K; }
 314 
 315   // Methods for tracing page sizes returned by the above method.
 316   // The region_{min,max}_size parameters should be the values
 317   // passed to page_size_for_region() and page_size should be the result of that
 318   // call.  The (optional) base and size parameters should come from the
 319   // ReservedSpace base() and size() methods.
 320   static void trace_page_sizes(const char* str, const size_t* page_sizes, int count);
 321   static void trace_page_sizes(const char* str,
 322                                const size_t region_min_size,
 323                                const size_t region_max_size,
 324                                const size_t page_size,
 325                                const char* base,
 326                                const size_t size);
 327   static void trace_page_sizes_for_requested_size(const char* str,
 328                                                   const size_t requested_size,
 329                                                   const size_t page_size,
 330                                                   const size_t alignment,
 331                                                   const char* base,
 332                                                   const size_t size);
 333 
 334   static int    vm_allocation_granularity();
 335   static char*  reserve_memory(size_t bytes, char* addr = 0,
 336                                size_t alignment_hint = 0, int file_desc = -1);
 337   static char*  reserve_memory(size_t bytes, char* addr,
 338                                size_t alignment_hint, MEMFLAGS flags);
 339   static char*  reserve_memory_aligned(size_t size, size_t alignment, int file_desc = -1);
 340   static char*  attempt_reserve_memory_at(size_t bytes, char* addr, int file_desc = -1);
 341   static void   split_reserved_memory(char *base, size_t size,
 342                                       size_t split, bool realloc);
 343   static bool   commit_memory(char* addr, size_t bytes, bool executable);
 344   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 345                               bool executable);
 346   // Same as commit_memory() that either succeeds or calls
 347   // vm_exit_out_of_memory() with the specified mesg.
 348   static void   commit_memory_or_exit(char* addr, size_t bytes,
 349                                       bool executable, const char* mesg);
 350   static void   commit_memory_or_exit(char* addr, size_t size,
 351                                       size_t alignment_hint,
 352                                       bool executable, const char* mesg);
 353   static bool   uncommit_memory(char* addr, size_t bytes);
 354   static bool   release_memory(char* addr, size_t bytes);
 355 
 356   // Touch memory pages that cover the memory range from start to end (exclusive)
 357   // to make the OS back the memory range with actual memory.
 358   // Current implementation may not touch the last page if unaligned addresses
 359   // are passed.
 360   static void   pretouch_memory(void* start, void* end, size_t page_size = vm_page_size());
 361 
 362   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 363   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 364                                bool is_committed = true);
 365 
 366   static bool   guard_memory(char* addr, size_t bytes);
 367   static bool   unguard_memory(char* addr, size_t bytes);
 368   static bool   create_stack_guard_pages(char* addr, size_t bytes);
 369   static bool   pd_create_stack_guard_pages(char* addr, size_t bytes);
 370   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
 371   // Helper function to create a new file with template jvmheap.XXXXXX.
 372   // Returns a valid fd on success or else returns -1
 373   static int create_file_for_heap(const char* dir);
 374   // Map memory to the file referred by fd. This function is slightly different from map_memory()
 375   // and is added to be used for implementation of -XX:AllocateHeapAt
 376   static char* map_memory_to_file(char* base, size_t size, int fd);
 377   // Replace existing reserved memory with file mapping
 378   static char* replace_existing_mapping_with_file_mapping(char* base, size_t size, int fd);
 379 
 380   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 381                            char *addr, size_t bytes, bool read_only = false,
 382                            bool allow_exec = false);
 383   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 384                              char *addr, size_t bytes, bool read_only,
 385                              bool allow_exec);
 386   static bool   unmap_memory(char *addr, size_t bytes);
 387   static void   free_memory(char *addr, size_t bytes, size_t alignment_hint);
 388   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 389 
 390   // NUMA-specific interface
 391   static bool   numa_has_static_binding();
 392   static bool   numa_has_group_homing();
 393   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 394   static void   numa_make_global(char *addr, size_t bytes);
 395   static size_t numa_get_groups_num();
 396   static size_t numa_get_leaf_groups(int *ids, size_t size);
 397   static bool   numa_topology_changed();
 398   static int    numa_get_group_id();
 399 
 400   // Page manipulation
 401   struct page_info {
 402     size_t size;
 403     int lgrp_id;
 404   };
 405   static bool   get_page_info(char *start, page_info* info);
 406   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 407 
 408   static char*  non_memory_address_word();
 409   // reserve, commit and pin the entire memory region
 410   static char*  reserve_memory_special(size_t size, size_t alignment,
 411                                        char* addr, bool executable);
 412   static bool   release_memory_special(char* addr, size_t bytes);
 413   static void   large_page_init();
 414   static size_t large_page_size();
 415   static bool   can_commit_large_page_memory();
 416   static bool   can_execute_large_page_memory();
 417 
 418   // OS interface to polling page
 419   static address get_polling_page()             { return _polling_page; }
 420   static void    set_polling_page(address page) { _polling_page = page; }
 421   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 422   static void    make_polling_page_unreadable();
 423   static void    make_polling_page_readable();
 424 
 425   // Check if pointer points to readable memory (by 4-byte read access)
 426   static bool    is_readable_pointer(const void* p);
 427   static bool    is_readable_range(const void* from, const void* to);
 428 
 429   // threads
 430 
 431   enum ThreadType {
 432     vm_thread,
 433     cgc_thread,        // Concurrent GC thread
 434     pgc_thread,        // Parallel GC thread
 435     java_thread,       // Java, CodeCacheSweeper, JVMTIAgent and Service threads.
 436     compiler_thread,
 437     watcher_thread,
 438     os_thread
 439   };
 440 
 441   static bool create_thread(Thread* thread,
 442                             ThreadType thr_type,
 443                             size_t req_stack_size = 0);
 444 
 445   // The "main thread", also known as "starting thread", is the thread
 446   // that loads/creates the JVM via JNI_CreateJavaVM.
 447   static bool create_main_thread(JavaThread* thread);
 448 
 449   // The primordial thread is the initial process thread. The java
 450   // launcher never uses the primordial thread as the main thread, but
 451   // applications that host the JVM directly may do so. Some platforms
 452   // need special-case handling of the primordial thread if it attaches
 453   // to the VM.
 454   static bool is_primordial_thread(void)
 455 #if defined(_WINDOWS) || defined(BSD)
 456     // No way to identify the primordial thread.
 457     { return false; }
 458 #else
 459   ;
 460 #endif
 461 
 462   static bool create_attached_thread(JavaThread* thread);
 463   static void pd_start_thread(Thread* thread);
 464   static void start_thread(Thread* thread);
 465 
 466   // Returns true if successful.
 467   static bool signal_thread(Thread* thread, int sig, const char* reason);
 468 
 469   static void free_thread(OSThread* osthread);
 470 
 471   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 472   static intx current_thread_id();
 473   static int current_process_id();
 474   static int sleep(Thread* thread, jlong ms, bool interruptable);
 475   // Short standalone OS sleep suitable for slow path spin loop.
 476   // Ignores Thread.interrupt() (so keep it short).
 477   // ms = 0, will sleep for the least amount of time allowed by the OS.
 478   static void naked_short_sleep(jlong ms);
 479   static void naked_short_nanosleep(jlong ns);
 480   static void infinite_sleep(); // never returns, use with CAUTION
 481   static void naked_yield () ;
 482   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 483   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 484 
 485   static void interrupt(Thread* thread);
 486   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 487 
 488   static int pd_self_suspend_thread(Thread* thread);
 489 
 490   static ExtendedPC fetch_frame_from_context(const void* ucVoid, intptr_t** sp, intptr_t** fp);
 491   static frame      fetch_frame_from_context(const void* ucVoid);
 492   static frame      fetch_frame_from_ucontext(Thread* thread, void* ucVoid);
 493 
 494   static void breakpoint();
 495   static bool start_debugging(char *buf, int buflen);
 496 
 497   static address current_stack_pointer();
 498   static address current_stack_base();
 499   static size_t current_stack_size();
 500 
 501   static void verify_stack_alignment() PRODUCT_RETURN;
 502 
 503   static bool message_box(const char* title, const char* message);
 504   static char* do_you_want_to_debug(const char* message);
 505 
 506   // run cmd in a separate process and return its exit code; or -1 on failures
 507   static int fork_and_exec(char *cmd, bool use_vfork_if_available = false);
 508 
 509   // Call ::exit() on all platforms but Windows
 510   static void exit(int num);
 511 
 512   // Terminate the VM, but don't exit the process
 513   static void shutdown();
 514 
 515   // Terminate with an error.  Default is to generate a core file on platforms
 516   // that support such things.  This calls shutdown() and then aborts.
 517   static void abort(bool dump_core, void *siginfo, const void *context);
 518   static void abort(bool dump_core = true);
 519 
 520   // Die immediately, no exit hook, no abort hook, no cleanup.
 521   static void die();
 522 
 523   // File i/o operations
 524   static const int default_file_open_flags();
 525   static int open(const char *path, int oflag, int mode);
 526   static FILE* open(int fd, const char* mode);
 527   static FILE* fopen(const char* path, const char* mode);
 528   static int close(int fd);
 529   static jlong lseek(int fd, jlong offset, int whence);
 530   // This function, on Windows, canonicalizes a given path (see os_windows.cpp for details).
 531   // On Posix, this function is a noop: it does not change anything and just returns
 532   // the input pointer.
 533   static char* native_path(char *path);
 534   static int ftruncate(int fd, jlong length);
 535   static int fsync(int fd);
 536   static int available(int fd, jlong *bytes);
 537   static int get_fileno(FILE* fp);
 538   static void flockfile(FILE* fp);
 539   static void funlockfile(FILE* fp);
 540 
 541   static int compare_file_modified_times(const char* file1, const char* file2);
 542 
 543   //File i/o operations
 544 
 545   static ssize_t read(int fd, void *buf, unsigned int nBytes);
 546   static ssize_t read_at(int fd, void *buf, unsigned int nBytes, jlong offset);
 547   static size_t write(int fd, const void *buf, unsigned int nBytes);
 548 
 549   // Reading directories.
 550   static DIR*           opendir(const char* dirname);
 551   static struct dirent* readdir(DIR* dirp);
 552   static int            closedir(DIR* dirp);
 553 
 554   // Dynamic library extension
 555   static const char*    dll_file_extension();
 556 
 557   static const char*    get_temp_directory();
 558   static const char*    get_current_directory(char *buf, size_t buflen);
 559 
 560   // Builds the platform-specific name of a library.
 561   // Returns false if the buffer is too small.
 562   static bool           dll_build_name(char* buffer, size_t size,
 563                                        const char* fname);
 564 
 565   // Builds a platform-specific full library path given an ld path and
 566   // unadorned library name. Returns true if the buffer contains a full
 567   // path to an existing file, false otherwise. If pathname is empty,
 568   // uses the path to the current directory.
 569   static bool           dll_locate_lib(char* buffer, size_t size,
 570                                        const char* pathname, const char* fname);
 571 
 572   // Symbol lookup, find nearest function name; basically it implements
 573   // dladdr() for all platforms. Name of the nearest function is copied
 574   // to buf. Distance from its base address is optionally returned as offset.
 575   // If function name is not found, buf[0] is set to '\0' and offset is
 576   // set to -1 (if offset is non-NULL).
 577   static bool dll_address_to_function_name(address addr, char* buf,
 578                                            int buflen, int* offset,
 579                                            bool demangle = true);
 580 
 581   // Locate DLL/DSO. On success, full path of the library is copied to
 582   // buf, and offset is optionally set to be the distance between addr
 583   // and the library's base address. On failure, buf[0] is set to '\0'
 584   // and offset is set to -1 (if offset is non-NULL).
 585   static bool dll_address_to_library_name(address addr, char* buf,
 586                                           int buflen, int* offset);
 587 
 588   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 589   static bool address_is_in_vm(address addr);
 590 
 591   // Loads .dll/.so and
 592   // in case of error it checks if .dll/.so was built for the
 593   // same architecture as HotSpot is running on
 594   // in case of an error NULL is returned and an error message is stored in ebuf
 595   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 596 
 597   // lookup symbol in a shared library
 598   static void* dll_lookup(void* handle, const char* name);
 599 
 600   // Unload library
 601   static void  dll_unload(void *lib);
 602 
 603   // Callback for loaded module information
 604   // Input parameters:
 605   //    char*     module_file_name,
 606   //    address   module_base_addr,
 607   //    address   module_top_addr,
 608   //    void*     param
 609   typedef int (*LoadedModulesCallbackFunc)(const char *, address, address, void *);
 610 
 611   static int get_loaded_modules_info(LoadedModulesCallbackFunc callback, void *param);
 612 
 613   // Return the handle of this process
 614   static void* get_default_process_handle();
 615 
 616   // Check for static linked agent library
 617   static bool find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 618                                  size_t syms_len);
 619 
 620   // Find agent entry point
 621   static void *find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 622                                    const char *syms[], size_t syms_len);
 623 
 624   // Provide C99 compliant versions of these functions, since some versions
 625   // of some platforms don't.
 626   static int vsnprintf(char* buf, size_t len, const char* fmt, va_list args) ATTRIBUTE_PRINTF(3, 0);
 627   static int snprintf(char* buf, size_t len, const char* fmt, ...) ATTRIBUTE_PRINTF(3, 4);
 628 
 629   // Get host name in buffer provided
 630   static bool get_host_name(char* buf, size_t buflen);
 631 
 632   // Print out system information; they are called by fatal error handler.
 633   // Output format may be different on different platforms.
 634   static void print_os_info(outputStream* st);
 635   static void print_os_info_brief(outputStream* st);
 636   static void print_cpu_info(outputStream* st, char* buf, size_t buflen);
 637   static void pd_print_cpu_info(outputStream* st, char* buf, size_t buflen);
 638   static void print_summary_info(outputStream* st, char* buf, size_t buflen);
 639   static void print_memory_info(outputStream* st);
 640   static void print_dll_info(outputStream* st);
 641   static void print_environment_variables(outputStream* st, const char** env_list);
 642   static void print_context(outputStream* st, const void* context);
 643   static void print_register_info(outputStream* st, const void* context);
 644   static bool signal_sent_by_kill(const void* siginfo);
 645   static void print_siginfo(outputStream* st, const void* siginfo);
 646   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 647   static void print_date_and_time(outputStream* st, char* buf, size_t buflen);
 648   static void print_instructions(outputStream* st, address pc, int unitsize);
 649 
 650   static void print_location(outputStream* st, intptr_t x, bool verbose = false);
 651   static size_t lasterror(char *buf, size_t len);
 652   static int get_last_error();
 653 
 654   // Replacement for strerror().
 655   // Will return the english description of the error (e.g. "File not found", as
 656   //  suggested in the POSIX standard.
 657   // Will return "Unknown error" for an unknown errno value.
 658   // Will not attempt to localize the returned string.
 659   // Will always return a valid string which is a static constant.
 660   // Will not change the value of errno.
 661   static const char* strerror(int e);
 662 
 663   // Will return the literalized version of the given errno (e.g. "EINVAL"
 664   //  for EINVAL).
 665   // Will return "Unknown error" for an unknown errno value.
 666   // Will always return a valid string which is a static constant.
 667   // Will not change the value of errno.
 668   static const char* errno_name(int e);
 669 
 670   // Determines whether the calling process is being debugged by a user-mode debugger.
 671   static bool is_debugger_attached();
 672 
 673   // wait for a key press if PauseAtExit is set
 674   static void wait_for_keypress_at_exit(void);
 675 
 676   // The following two functions are used by fatal error handler to trace
 677   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 678   // frame.hpp/cpp assume thread is JavaThread, and also because different
 679   // OS/compiler may have different convention or provide different API to
 680   // walk C frames.
 681   //
 682   // We don't attempt to become a debugger, so we only follow frames if that
 683   // does not require a lookup in the unwind table, which is part of the binary
 684   // file but may be unsafe to read after a fatal error. So on x86, we can
 685   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 686   // possible to walk C stack without having the unwind table.
 687   static bool is_first_C_frame(frame *fr);
 688   static frame get_sender_for_C_frame(frame *fr);
 689 
 690   // return current frame. pc() and sp() are set to NULL on failure.
 691   static frame      current_frame();
 692 
 693   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 694 
 695   // returns a string to describe the exception/signal;
 696   // returns NULL if exception_code is not an OS exception/signal.
 697   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 698 
 699   // Returns the signal number (e.g. 11) for a given signal name (SIGSEGV).
 700   static int get_signal_number(const char* signal_name);
 701 
 702   // Returns native Java library, loads if necessary
 703   static void*    native_java_library();
 704 
 705   // Fills in path to jvm.dll/libjvm.so (used by the Disassembler)
 706   static void     jvm_path(char *buf, jint buflen);
 707 
 708   // JNI names
 709   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 710   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 711 
 712   // Init os specific system properties values
 713   static void init_system_properties_values();
 714 
 715   // IO operations, non-JVM_ version.
 716   static int stat(const char* path, struct stat* sbuf);
 717   static bool dir_is_empty(const char* path);
 718 
 719   // IO operations on binary files
 720   static int create_binary_file(const char* path, bool rewrite_existing);
 721   static jlong current_file_offset(int fd);
 722   static jlong seek_to_file_offset(int fd, jlong offset);
 723 
 724   // Retrieve native stack frames.
 725   // Parameter:
 726   //   stack:  an array to storage stack pointers.
 727   //   frames: size of above array.
 728   //   toSkip: number of stack frames to skip at the beginning.
 729   // Return: number of stack frames captured.
 730   static int get_native_stack(address* stack, int size, int toSkip = 0);
 731 
 732   // General allocation (must be MT-safe)
 733   static void* malloc  (size_t size, MEMFLAGS flags, const NativeCallStack& stack);
 734   static void* malloc  (size_t size, MEMFLAGS flags);
 735   static void* realloc (void *memblock, size_t size, MEMFLAGS flag, const NativeCallStack& stack);
 736   static void* realloc (void *memblock, size_t size, MEMFLAGS flag);
 737 
 738   static void  free    (void *memblock);
 739   static char* strdup(const char *, MEMFLAGS flags = mtInternal);  // Like strdup
 740   // Like strdup, but exit VM when strdup() returns NULL
 741   static char* strdup_check_oom(const char*, MEMFLAGS flags = mtInternal);
 742 
 743 #ifndef PRODUCT
 744   static julong num_mallocs;         // # of calls to malloc/realloc
 745   static julong alloc_bytes;         // # of bytes allocated
 746   static julong num_frees;           // # of calls to free
 747   static julong free_bytes;          // # of bytes freed
 748 #endif
 749 
 750   // SocketInterface (ex HPI SocketInterface )
 751   static int socket(int domain, int type, int protocol);
 752   static int socket_close(int fd);
 753   static int recv(int fd, char* buf, size_t nBytes, uint flags);
 754   static int send(int fd, char* buf, size_t nBytes, uint flags);
 755   static int raw_send(int fd, char* buf, size_t nBytes, uint flags);
 756   static int connect(int fd, struct sockaddr* him, socklen_t len);
 757   static struct hostent* get_host_by_name(char* name);
 758 
 759   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 760   static void  initialize_jdk_signal_support(TRAPS);
 761   static void  signal_notify(int signal_number);
 762   static void* signal(int signal_number, void* handler);
 763   static void  signal_raise(int signal_number);
 764   static int   signal_wait();
 765   static void* user_handler();
 766   static void  terminate_signal_thread();
 767   static int   sigexitnum_pd();
 768 
 769   // random number generation
 770   static int random();                     // return 32bit pseudorandom number
 771   static void init_random(unsigned int initval);    // initialize random sequence
 772 
 773   // Structured OS Exception support
 774   static void os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread);
 775 
 776   // On Posix compatible OS it will simply check core dump limits while on Windows
 777   // it will check if dump file can be created. Check or prepare a core dump to be
 778   // taken at a later point in the same thread in os::abort(). Use the caller
 779   // provided buffer as a scratch buffer. The status message which will be written
 780   // into the error log either is file location or a short error message, depending
 781   // on the checking result.
 782   static void check_dump_limit(char* buffer, size_t bufferSize);
 783 
 784   // Get the default path to the core file
 785   // Returns the length of the string
 786   static int get_core_path(char* buffer, size_t bufferSize);
 787 
 788   // JVMTI & JVM monitoring and management support
 789   // The thread_cpu_time() and current_thread_cpu_time() are only
 790   // supported if is_thread_cpu_time_supported() returns true.
 791   // They are not supported on Solaris T1.
 792 
 793   // Thread CPU Time - return the fast estimate on a platform
 794   // On Solaris - call gethrvtime (fast) - user time only
 795   // On Linux   - fast clock_gettime where available - user+sys
 796   //            - otherwise: very slow /proc fs - user+sys
 797   // On Windows - GetThreadTimes - user+sys
 798   static jlong current_thread_cpu_time();
 799   static jlong thread_cpu_time(Thread* t);
 800 
 801   // Thread CPU Time with user_sys_cpu_time parameter.
 802   //
 803   // If user_sys_cpu_time is true, user+sys time is returned.
 804   // Otherwise, only user time is returned
 805   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 806   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 807 
 808   // Return a bunch of info about the timers.
 809   // Note that the returned info for these two functions may be different
 810   // on some platforms
 811   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 812   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 813 
 814   static bool is_thread_cpu_time_supported();
 815 
 816   // System loadavg support.  Returns -1 if load average cannot be obtained.
 817   static int loadavg(double loadavg[], int nelem);
 818 
 819   // Amount beyond the callee frame size that we bang the stack.
 820   static int extra_bang_size_in_bytes();
 821 
 822   static char** split_path(const char* path, int* n);
 823 
 824   // Extensions
 825 #include "runtime/os_ext.hpp"
 826 
 827  public:
 828   class CrashProtectionCallback : public StackObj {
 829   public:
 830     virtual void call() = 0;
 831   };
 832 
 833   // Platform dependent stuff
 834 #ifndef _WINDOWS
 835 # include "os_posix.hpp"
 836 #endif
 837 #include OS_CPU_HEADER(os)
 838 #include OS_HEADER(os)
 839 
 840 #ifndef OS_NATIVE_THREAD_CREATION_FAILED_MSG
 841 #define OS_NATIVE_THREAD_CREATION_FAILED_MSG "unable to create native thread: possibly out of memory or process/resource limits reached"
 842 #endif
 843 
 844  public:
 845 #ifndef PLATFORM_PRINT_NATIVE_STACK
 846   // No platform-specific code for printing the native stack.
 847   static bool platform_print_native_stack(outputStream* st, const void* context,
 848                                           char *buf, int buf_size) {
 849     return false;
 850   }
 851 #endif
 852 
 853   // debugging support (mostly used by debug.cpp but also fatal error handler)
 854   static bool find(address pc, outputStream* st = tty); // OS specific function to make sense out of an address
 855 
 856   static bool dont_yield();                     // when true, JVM_Yield() is nop
 857   static void print_statistics();
 858 
 859   // Thread priority helpers (implemented in OS-specific part)
 860   static OSReturn set_native_priority(Thread* thread, int native_prio);
 861   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 862   static int java_to_os_priority[CriticalPriority + 1];
 863   // Hint to the underlying OS that a task switch would not be good.
 864   // Void return because it's a hint and can fail.
 865   static const char* native_thread_creation_failed_msg() {
 866     return OS_NATIVE_THREAD_CREATION_FAILED_MSG;
 867   }
 868 
 869   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 870   // Causes the VM to wait until an external stimulus has been applied
 871   // (for Unix, that stimulus is a signal, for Windows, an external
 872   // ResumeThread call)
 873   static void pause();
 874 
 875   // Builds a platform dependent Agent_OnLoad_<libname> function name
 876   // which is used to find statically linked in agents.
 877   static char*  build_agent_function_name(const char *sym, const char *cname,
 878                                           bool is_absolute_path);
 879 
 880   class SuspendedThreadTaskContext {
 881   public:
 882     SuspendedThreadTaskContext(Thread* thread, void *ucontext) : _thread(thread), _ucontext(ucontext) {}
 883     Thread* thread() const { return _thread; }
 884     void* ucontext() const { return _ucontext; }
 885   private:
 886     Thread* _thread;
 887     void* _ucontext;
 888   };
 889 
 890   class SuspendedThreadTask {
 891   public:
 892     SuspendedThreadTask(Thread* thread) : _thread(thread), _done(false) {}
 893     void run();
 894     bool is_done() { return _done; }
 895     virtual void do_task(const SuspendedThreadTaskContext& context) = 0;
 896   protected:
 897     ~SuspendedThreadTask() {}
 898   private:
 899     void internal_do_task();
 900     Thread* _thread;
 901     bool _done;
 902   };
 903 
 904 #ifndef _WINDOWS
 905   // Suspend/resume support
 906   // Protocol:
 907   //
 908   // a thread starts in SR_RUNNING
 909   //
 910   // SR_RUNNING can go to
 911   //   * SR_SUSPEND_REQUEST when the WatcherThread wants to suspend it
 912   // SR_SUSPEND_REQUEST can go to
 913   //   * SR_RUNNING if WatcherThread decides it waited for SR_SUSPENDED too long (timeout)
 914   //   * SR_SUSPENDED if the stopped thread receives the signal and switches state
 915   // SR_SUSPENDED can go to
 916   //   * SR_WAKEUP_REQUEST when the WatcherThread has done the work and wants to resume
 917   // SR_WAKEUP_REQUEST can go to
 918   //   * SR_RUNNING when the stopped thread receives the signal
 919   //   * SR_WAKEUP_REQUEST on timeout (resend the signal and try again)
 920   class SuspendResume {
 921    public:
 922     enum State {
 923       SR_RUNNING,
 924       SR_SUSPEND_REQUEST,
 925       SR_SUSPENDED,
 926       SR_WAKEUP_REQUEST
 927     };
 928 
 929   private:
 930     volatile State _state;
 931 
 932   private:
 933     /* try to switch state from state "from" to state "to"
 934      * returns the state set after the method is complete
 935      */
 936     State switch_state(State from, State to);
 937 
 938   public:
 939     SuspendResume() : _state(SR_RUNNING) { }
 940 
 941     State state() const { return _state; }
 942 
 943     State request_suspend() {
 944       return switch_state(SR_RUNNING, SR_SUSPEND_REQUEST);
 945     }
 946 
 947     State cancel_suspend() {
 948       return switch_state(SR_SUSPEND_REQUEST, SR_RUNNING);
 949     }
 950 
 951     State suspended() {
 952       return switch_state(SR_SUSPEND_REQUEST, SR_SUSPENDED);
 953     }
 954 
 955     State request_wakeup() {
 956       return switch_state(SR_SUSPENDED, SR_WAKEUP_REQUEST);
 957     }
 958 
 959     State running() {
 960       return switch_state(SR_WAKEUP_REQUEST, SR_RUNNING);
 961     }
 962 
 963     bool is_running() const {
 964       return _state == SR_RUNNING;
 965     }
 966 
 967     bool is_suspend_request() const {
 968       return _state == SR_SUSPEND_REQUEST;
 969     }
 970 
 971     bool is_suspended() const {
 972       return _state == SR_SUSPENDED;
 973     }
 974   };
 975 #endif // !WINDOWS
 976 
 977 
 978  protected:
 979   static volatile unsigned int _rand_seed;    // seed for random number generator
 980   static int _processor_count;                // number of processors
 981   static int _initial_active_processor_count; // number of active processors during initialization.
 982 
 983   static char* format_boot_path(const char* format_string,
 984                                 const char* home,
 985                                 int home_len,
 986                                 char fileSep,
 987                                 char pathSep);
 988   static bool set_boot_path(char fileSep, char pathSep);
 989 
 990 };
 991 
 992 #ifndef _WINDOWS
 993 template<> struct IsRegisteredEnum<os::SuspendResume::State> : public TrueType {};
 994 #endif // !_WINDOWS
 995 
 996 // Note that "PAUSE" is almost always used with synchronization
 997 // so arguably we should provide Atomic::SpinPause() instead
 998 // of the global SpinPause() with C linkage.
 999 // It'd also be eligible for inlining on many platforms.
1000 
1001 extern "C" int SpinPause();
1002 
1003 #endif // SHARE_RUNTIME_OS_HPP