1 /*
   2  * Copyright (c) 1997, 2018, 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 "jvm.h"
  29 #include "jvmtifiles/jvmti.h"
  30 #include "metaprogramming/isRegisteredEnum.hpp"
  31 #include "metaprogramming/integralConstant.hpp"
  32 #include "runtime/extendedPC.hpp"
  33 #include "runtime/handles.hpp"
  34 #include "utilities/macros.hpp"
  35 #ifndef _WINDOWS
  36 # include <setjmp.h>
  37 #endif
  38 #ifdef __APPLE__
  39 # include <mach/mach_time.h>
  40 #endif
  41 
  42 class AgentLibrary;
  43 class frame;
  44 
  45 // os defines the interface to operating system; this includes traditional
  46 // OS services (time, I/O) as well as other functionality with system-
  47 // dependent code.
  48 
  49 typedef void (*dll_func)(...);
  50 
  51 class Thread;
  52 class JavaThread;
  53 class Event;
  54 class DLL;
  55 class FileHandle;
  56 class NativeCallStack;
  57 
  58 template<class E> class GrowableArray;
  59 
  60 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  61 
  62 // Platform-independent error return values from OS functions
  63 enum OSReturn {
  64   OS_OK         =  0,        // Operation was successful
  65   OS_ERR        = -1,        // Operation failed
  66   OS_INTRPT     = -2,        // Operation was interrupted
  67   OS_TIMEOUT    = -3,        // Operation timed out
  68   OS_NOMEM      = -5,        // Operation failed for lack of memory
  69   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  70 };
  71 
  72 enum ThreadPriority {        // JLS 20.20.1-3
  73   NoPriority       = -1,     // Initial non-priority value
  74   MinPriority      =  1,     // Minimum priority
  75   NormPriority     =  5,     // Normal (non-daemon) priority
  76   NearMaxPriority  =  9,     // High priority, used for VMThread
  77   MaxPriority      = 10,     // Highest priority, used for WatcherThread
  78                              // ensures that VMThread doesn't starve profiler
  79   CriticalPriority = 11      // Critical thread priority
  80 };
  81 
  82 // Executable parameter flag for os::commit_memory() and
  83 // os::commit_memory_or_exit().
  84 const bool ExecMem = true;
  85 
  86 // Typedef for structured exception handling support
  87 typedef void (*java_call_t)(JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread);
  88 
  89 class MallocTracker;
  90 
  91 class os: AllStatic {
  92   friend class VMStructs;
  93   friend class JVMCIVMStructs;
  94   friend class MallocTracker;
  95  public:
  96   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
  97 
  98  private:
  99   static OSThread*          _starting_thread;
 100   static address            _polling_page;
 101   static volatile int32_t * _mem_serialize_page;
 102   static uintptr_t          _serialize_page_mask;
 103  public:
 104   static size_t             _page_sizes[page_sizes_max];
 105 
 106  private:
 107   static void init_page_sizes(size_t default_page_size) {
 108     _page_sizes[0] = default_page_size;
 109     _page_sizes[1] = 0; // sentinel
 110   }
 111 
 112   static char*  pd_reserve_memory(size_t bytes, char* addr = 0,
 113                                   size_t alignment_hint = 0);
 114   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr);
 115   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr, int file_desc);
 116   static void   pd_split_reserved_memory(char *base, size_t size,
 117                                       size_t split, bool realloc);
 118   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
 119   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
 120                                  bool executable);
 121   // Same as pd_commit_memory() that either succeeds or calls
 122   // vm_exit_out_of_memory() with the specified mesg.
 123   static void   pd_commit_memory_or_exit(char* addr, size_t bytes,
 124                                          bool executable, const char* mesg);
 125   static void   pd_commit_memory_or_exit(char* addr, size_t size,
 126                                          size_t alignment_hint,
 127                                          bool executable, const char* mesg);
 128   static bool   pd_uncommit_memory(char* addr, size_t bytes);
 129   static bool   pd_release_memory(char* addr, size_t bytes);
 130 
 131   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
 132                            char *addr, size_t bytes, bool read_only = false,
 133                            bool allow_exec = false);
 134   static char*  pd_remap_memory(int fd, const char* file_name, size_t file_offset,
 135                              char *addr, size_t bytes, bool read_only,
 136                              bool allow_exec);
 137   static bool   pd_unmap_memory(char *addr, size_t bytes);
 138   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
 139   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 140 
 141   static size_t page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned);
 142 
 143   // Get summary strings for system information in buffer provided
 144   static void  get_summary_cpu_info(char* buf, size_t buflen);
 145   static void  get_summary_os_info(char* buf, size_t buflen);
 146 
 147   static void initialize_initial_active_processor_count();
 148 
 149   LINUX_ONLY(static void pd_init_container_support();)
 150 
 151  public:
 152   static void init(void);                      // Called before command line parsing
 153 
 154   static void init_container_support() {       // Called during command line parsing.
 155      LINUX_ONLY(pd_init_container_support();)
 156   }
 157 
 158   static void init_before_ergo(void);          // Called after command line parsing
 159                                                // before VM ergonomics processing.
 160   static jint init_2(void);                    // Called after command line parsing
 161                                                // and VM ergonomics processing
 162   static void init_globals(void) {             // Called from init_globals() in init.cpp
 163     init_globals_ext();
 164   }
 165 
 166   // File names are case-insensitive on windows only
 167   // Override me as needed
 168   static int    file_name_strcmp(const char* s1, const char* s2);
 169 
 170   // unset environment variable
 171   static bool unsetenv(const char* name);
 172 
 173   static bool have_special_privileges();
 174 
 175   static jlong  javaTimeMillis();
 176   static jlong  javaTimeNanos();
 177   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
 178   static void   javaTimeSystemUTC(jlong &seconds, jlong &nanos);
 179   static void   run_periodic_checks();
 180   static bool   supports_monotonic_clock();
 181 
 182   // Returns the elapsed time in seconds since the vm started.
 183   static double elapsedTime();
 184 
 185   // Returns real time in seconds since an arbitrary point
 186   // in the past.
 187   static bool getTimesSecs(double* process_real_time,
 188                            double* process_user_time,
 189                            double* process_system_time);
 190 
 191   // Interface to the performance counter
 192   static jlong elapsed_counter();
 193   static jlong elapsed_frequency();
 194 
 195   // The "virtual time" of a thread is the amount of time a thread has
 196   // actually run.  The first function indicates whether the OS supports
 197   // this functionality for the current thread, and if so:
 198   //   * the second enables vtime tracking (if that is required).
 199   //   * the third tells whether vtime is enabled.
 200   //   * the fourth returns the elapsed virtual time for the current
 201   //     thread.
 202   static bool supports_vtime();
 203   static bool enable_vtime();
 204   static bool vtime_enabled();
 205   static double elapsedVTime();
 206 
 207   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 208   // It is MT safe, but not async-safe, as reading time zone
 209   // information may require a lock on some platforms.
 210   static char*      local_time_string(char *buf, size_t buflen);
 211   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 212   static struct tm* gmtime_pd        (const time_t* clock, struct tm*  res);
 213   // Fill in buffer with current local time as an ISO-8601 string.
 214   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 215   // Returns buffer, or NULL if it failed.
 216   static char* iso8601_time(char* buffer, size_t buffer_length, bool utc = false);
 217 
 218   // Interface for detecting multiprocessor system
 219   static inline bool is_MP() {
 220     // During bootstrap if _processor_count is not yet initialized
 221     // we claim to be MP as that is safest. If any platform has a
 222     // stub generator that might be triggered in this phase and for
 223     // which being declared MP when in fact not, is a problem - then
 224     // the bootstrap routine for the stub generator needs to check
 225     // the processor count directly and leave the bootstrap routine
 226     // in place until called after initialization has ocurred.
 227     return AssumeMP || (_processor_count != 1);
 228   }
 229   static julong available_memory();
 230   static julong physical_memory();
 231   static bool has_allocatable_memory_limit(julong* limit);
 232   static bool is_server_class_machine();
 233 
 234   // number of CPUs
 235   static int processor_count() {
 236     return _processor_count;
 237   }
 238   static void set_processor_count(int count) { _processor_count = count; }
 239 
 240   // Returns the number of CPUs this process is currently allowed to run on.
 241   // Note that on some OSes this can change dynamically.
 242   static int active_processor_count();
 243 
 244   // At startup the number of active CPUs this process is allowed to run on.
 245   // This value does not change dynamically. May be different from active_processor_count().
 246   static int initial_active_processor_count() {
 247     assert(_initial_active_processor_count > 0, "Initial active processor count not set yet.");
 248     return _initial_active_processor_count;
 249   }
 250 
 251   // Bind processes to processors.
 252   //     This is a two step procedure:
 253   //     first you generate a distribution of processes to processors,
 254   //     then you bind processes according to that distribution.
 255   // Compute a distribution for number of processes to processors.
 256   //    Stores the processor id's into the distribution array argument.
 257   //    Returns true if it worked, false if it didn't.
 258   static bool distribute_processes(uint length, uint* distribution);
 259   // Binds the current process to a processor.
 260   //    Returns true if it worked, false if it didn't.
 261   static bool bind_to_processor(uint processor_id);
 262 
 263   // Give a name to the current thread.
 264   static void set_native_thread_name(const char *name);
 265 
 266   // Interface for stack banging (predetect possible stack overflow for
 267   // exception processing)  There are guard pages, and above that shadow
 268   // pages for stack overflow checking.
 269   static bool uses_stack_guard_pages();
 270   static bool must_commit_stack_guard_pages();
 271   static void map_stack_shadow_pages(address sp);
 272   static bool stack_shadow_pages_available(Thread *thread, const methodHandle& method, address sp);
 273 
 274   // OS interface to Virtual Memory
 275 
 276   // Return the default page size.
 277   static int    vm_page_size();
 278 
 279   // Returns the page size to use for a region of memory.
 280   // region_size / min_pages will always be greater than or equal to the
 281   // returned value. The returned value will divide region_size.
 282   static size_t page_size_for_region_aligned(size_t region_size, size_t min_pages);
 283 
 284   // Returns the page size to use for a region of memory.
 285   // region_size / min_pages will always be greater than or equal to the
 286   // returned value. The returned value might not divide region_size.
 287   static size_t page_size_for_region_unaligned(size_t region_size, size_t min_pages);
 288 
 289   // Return the largest page size that can be used
 290   static size_t max_page_size() {
 291     // The _page_sizes array is sorted in descending order.
 292     return _page_sizes[0];
 293   }
 294 
 295   // Methods for tracing page sizes returned by the above method.
 296   // The region_{min,max}_size parameters should be the values
 297   // passed to page_size_for_region() and page_size should be the result of that
 298   // call.  The (optional) base and size parameters should come from the
 299   // ReservedSpace base() and size() methods.
 300   static void trace_page_sizes(const char* str, const size_t* page_sizes, int count);
 301   static void trace_page_sizes(const char* str,
 302                                const size_t region_min_size,
 303                                const size_t region_max_size,
 304                                const size_t page_size,
 305                                const char* base,
 306                                const size_t size);
 307   static void trace_page_sizes_for_requested_size(const char* str,
 308                                                   const size_t requested_size,
 309                                                   const size_t page_size,
 310                                                   const size_t alignment,
 311                                                   const char* base,
 312                                                   const size_t size);
 313 
 314   static int    vm_allocation_granularity();
 315   static char*  reserve_memory(size_t bytes, char* addr = 0,
 316                                size_t alignment_hint = 0, int file_desc = -1);
 317   static char*  reserve_memory(size_t bytes, char* addr,
 318                                size_t alignment_hint, MEMFLAGS flags);
 319   static char*  reserve_memory_aligned(size_t size, size_t alignment, int file_desc = -1);
 320   static char*  attempt_reserve_memory_at(size_t bytes, char* addr, int file_desc = -1);
 321   static void   split_reserved_memory(char *base, size_t size,
 322                                       size_t split, bool realloc);
 323   static bool   commit_memory(char* addr, size_t bytes, bool executable);
 324   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 325                               bool executable);
 326   // Same as commit_memory() that either succeeds or calls
 327   // vm_exit_out_of_memory() with the specified mesg.
 328   static void   commit_memory_or_exit(char* addr, size_t bytes,
 329                                       bool executable, const char* mesg);
 330   static void   commit_memory_or_exit(char* addr, size_t size,
 331                                       size_t alignment_hint,
 332                                       bool executable, const char* mesg);
 333   static bool   uncommit_memory(char* addr, size_t bytes);
 334   static bool   release_memory(char* addr, size_t bytes);
 335 
 336   // Touch memory pages that cover the memory range from start to end (exclusive)
 337   // to make the OS back the memory range with actual memory.
 338   // Current implementation may not touch the last page if unaligned addresses
 339   // are passed.
 340   static void   pretouch_memory(void* start, void* end, size_t page_size = vm_page_size());
 341 
 342   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 343   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 344                                bool is_committed = true);
 345 
 346   static bool   guard_memory(char* addr, size_t bytes);
 347   static bool   unguard_memory(char* addr, size_t bytes);
 348   static bool   create_stack_guard_pages(char* addr, size_t bytes);
 349   static bool   pd_create_stack_guard_pages(char* addr, size_t bytes);
 350   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
 351   // Helper function to create a new file with template jvmheap.XXXXXX.
 352   // Returns a valid fd on success or else returns -1
 353   static int create_file_for_heap(const char* dir);
 354   // Map memory to the file referred by fd. This function is slightly different from map_memory()
 355   // and is added to be used for implementation of -XX:AllocateHeapAt
 356   static char* map_memory_to_file(char* base, size_t size, int fd);
 357   // Replace existing reserved memory with file mapping
 358   static char* replace_existing_mapping_with_file_mapping(char* base, size_t size, int fd);
 359 
 360   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 361                            char *addr, size_t bytes, bool read_only = false,
 362                            bool allow_exec = false);
 363   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 364                              char *addr, size_t bytes, bool read_only,
 365                              bool allow_exec);
 366   static bool   unmap_memory(char *addr, size_t bytes);
 367   static void   free_memory(char *addr, size_t bytes, size_t alignment_hint);
 368   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 369 
 370   // NUMA-specific interface
 371   static bool   numa_has_static_binding();
 372   static bool   numa_has_group_homing();
 373   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 374   static void   numa_make_global(char *addr, size_t bytes);
 375   static size_t numa_get_groups_num();
 376   static size_t numa_get_leaf_groups(int *ids, size_t size);
 377   static bool   numa_topology_changed();
 378   static int    numa_get_group_id();
 379 
 380   // Page manipulation
 381   struct page_info {
 382     size_t size;
 383     int lgrp_id;
 384   };
 385   static bool   get_page_info(char *start, page_info* info);
 386   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 387 
 388   static char*  non_memory_address_word();
 389   // reserve, commit and pin the entire memory region
 390   static char*  reserve_memory_special(size_t size, size_t alignment,
 391                                        char* addr, bool executable);
 392   static bool   release_memory_special(char* addr, size_t bytes);
 393   static void   large_page_init();
 394   static size_t large_page_size();
 395   static bool   can_commit_large_page_memory();
 396   static bool   can_execute_large_page_memory();
 397 
 398   // OS interface to polling page
 399   static address get_polling_page()             { return _polling_page; }
 400   static void    set_polling_page(address page) { _polling_page = page; }
 401   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 402   static void    make_polling_page_unreadable();
 403   static void    make_polling_page_readable();
 404 
 405   // Routines used to serialize the thread state without using membars
 406   static void    serialize_thread_states();
 407 
 408   // Since we write to the serialize page from every thread, we
 409   // want stores to be on unique cache lines whenever possible
 410   // in order to minimize CPU cross talk.  We pre-compute the
 411   // amount to shift the thread* to make this offset unique to
 412   // each thread.
 413   static int     get_serialize_page_shift_count() {
 414     return SerializePageShiftCount;
 415   }
 416 
 417   static void     set_serialize_page_mask(uintptr_t mask) {
 418     _serialize_page_mask = mask;
 419   }
 420 
 421   static unsigned int  get_serialize_page_mask() {
 422     return _serialize_page_mask;
 423   }
 424 
 425   static void    set_memory_serialize_page(address page);
 426 
 427   static address get_memory_serialize_page() {
 428     return (address)_mem_serialize_page;
 429   }
 430 
 431   static inline void write_memory_serialize_page(JavaThread *thread) {
 432     uintptr_t page_offset = ((uintptr_t)thread >>
 433                             get_serialize_page_shift_count()) &
 434                             get_serialize_page_mask();
 435     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
 436   }
 437 
 438   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
 439     if (UseMembar) return false;
 440     // Previously this function calculated the exact address of this
 441     // thread's serialize page, and checked if the faulting address
 442     // was equal.  However, some platforms mask off faulting addresses
 443     // to the page size, so now we just check that the address is
 444     // within the page.  This makes the thread argument unnecessary,
 445     // but we retain the NULL check to preserve existing behavior.
 446     if (thread == NULL) return false;
 447     address page = (address) _mem_serialize_page;
 448     return addr >= page && addr < (page + os::vm_page_size());
 449   }
 450 
 451   static void block_on_serialize_page_trap();
 452 
 453   // threads
 454 
 455   enum ThreadType {
 456     vm_thread,
 457     cgc_thread,        // Concurrent GC thread
 458     pgc_thread,        // Parallel GC thread
 459     java_thread,       // Java, CodeCacheSweeper, JVMTIAgent and Service threads.
 460     compiler_thread,
 461     watcher_thread,
 462     os_thread
 463   };
 464 
 465   static bool create_thread(Thread* thread,
 466                             ThreadType thr_type,
 467                             size_t req_stack_size = 0);
 468 
 469   // The "main thread", also known as "starting thread", is the thread
 470   // that loads/creates the JVM via JNI_CreateJavaVM.
 471   static bool create_main_thread(JavaThread* thread);
 472 
 473   // The primordial thread is the initial process thread. The java
 474   // launcher never uses the primordial thread as the main thread, but
 475   // applications that host the JVM directly may do so. Some platforms
 476   // need special-case handling of the primordial thread if it attaches
 477   // to the VM.
 478   static bool is_primordial_thread(void)
 479 #if defined(_WINDOWS) || defined(BSD)
 480     // No way to identify the primordial thread.
 481     { return false; }
 482 #else
 483   ;
 484 #endif
 485 
 486   static bool create_attached_thread(JavaThread* thread);
 487   static void pd_start_thread(Thread* thread);
 488   static void start_thread(Thread* thread);
 489 
 490   static void initialize_thread(Thread* thr);
 491   static void free_thread(OSThread* osthread);
 492 
 493   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 494   static intx current_thread_id();
 495   static int current_process_id();
 496   static int sleep(Thread* thread, jlong ms, bool interruptable);
 497   // Short standalone OS sleep suitable for slow path spin loop.
 498   // Ignores Thread.interrupt() (so keep it short).
 499   // ms = 0, will sleep for the least amount of time allowed by the OS.
 500   static void naked_short_sleep(jlong ms);
 501   static void infinite_sleep(); // never returns, use with CAUTION
 502   static void naked_yield () ;
 503   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 504   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 505 
 506   static void interrupt(Thread* thread);
 507   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 508 
 509   static int pd_self_suspend_thread(Thread* thread);
 510 
 511   static ExtendedPC fetch_frame_from_context(const void* ucVoid, intptr_t** sp, intptr_t** fp);
 512   static frame      fetch_frame_from_context(const void* ucVoid);
 513   static frame      fetch_frame_from_ucontext(Thread* thread, void* ucVoid);
 514 
 515   static void breakpoint();
 516   static bool start_debugging(char *buf, int buflen);
 517 
 518   static address current_stack_pointer();
 519   static address current_stack_base();
 520   static size_t current_stack_size();
 521 
 522   static void verify_stack_alignment() PRODUCT_RETURN;
 523 
 524   static bool message_box(const char* title, const char* message);
 525   static char* do_you_want_to_debug(const char* message);
 526 
 527   // run cmd in a separate process and return its exit code; or -1 on failures
 528   static int fork_and_exec(char *cmd);
 529 
 530   // Call ::exit() on all platforms but Windows
 531   static void exit(int num);
 532 
 533   // Terminate the VM, but don't exit the process
 534   static void shutdown();
 535 
 536   // Terminate with an error.  Default is to generate a core file on platforms
 537   // that support such things.  This calls shutdown() and then aborts.
 538   static void abort(bool dump_core, void *siginfo, const void *context);
 539   static void abort(bool dump_core = true);
 540 
 541   // Die immediately, no exit hook, no abort hook, no cleanup.
 542   static void die();
 543 
 544   // File i/o operations
 545   static const int default_file_open_flags();
 546   static int open(const char *path, int oflag, int mode);
 547   static FILE* open(int fd, const char* mode);
 548   static int close(int fd);
 549   static jlong lseek(int fd, jlong offset, int whence);
 550   static char* native_path(char *path);
 551   static int ftruncate(int fd, jlong length);
 552   static int fsync(int fd);
 553   static int available(int fd, jlong *bytes);
 554   static int get_fileno(FILE* fp);
 555   static void flockfile(FILE* fp);
 556   static void funlockfile(FILE* fp);
 557 
 558   static int compare_file_modified_times(const char* file1, const char* file2);
 559 
 560   //File i/o operations
 561 
 562   static size_t read(int fd, void *buf, unsigned int nBytes);
 563   static size_t read_at(int fd, void *buf, unsigned int nBytes, jlong offset);
 564   static size_t restartable_read(int fd, void *buf, unsigned int nBytes);
 565   static size_t write(int fd, const void *buf, unsigned int nBytes);
 566 
 567   // Reading directories.
 568   static DIR*           opendir(const char* dirname);
 569   static int            readdir_buf_size(const char *path);
 570   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
 571   static int            closedir(DIR* dirp);
 572 
 573   // Dynamic library extension
 574   static const char*    dll_file_extension();
 575 
 576   static const char*    get_temp_directory();
 577   static const char*    get_current_directory(char *buf, size_t buflen);
 578 
 579   // Builds the platform-specific name of a library.
 580   // Returns false if the buffer is too small.
 581   static bool           dll_build_name(char* buffer, size_t size,
 582                                        const char* fname);
 583 
 584   // Builds a platform-specific full library path given an ld path and
 585   // unadorned library name. Returns true if the buffer contains a full
 586   // path to an existing file, false otherwise. If pathname is empty,
 587   // uses the path to the current directory.
 588   static bool           dll_locate_lib(char* buffer, size_t size,
 589                                        const char* pathname, const char* fname);
 590 
 591   // Symbol lookup, find nearest function name; basically it implements
 592   // dladdr() for all platforms. Name of the nearest function is copied
 593   // to buf. Distance from its base address is optionally returned as offset.
 594   // If function name is not found, buf[0] is set to '\0' and offset is
 595   // set to -1 (if offset is non-NULL).
 596   static bool dll_address_to_function_name(address addr, char* buf,
 597                                            int buflen, int* offset,
 598                                            bool demangle = true);
 599 
 600   // Locate DLL/DSO. On success, full path of the library is copied to
 601   // buf, and offset is optionally set to be the distance between addr
 602   // and the library's base address. On failure, buf[0] is set to '\0'
 603   // and offset is set to -1 (if offset is non-NULL).
 604   static bool dll_address_to_library_name(address addr, char* buf,
 605                                           int buflen, int* offset);
 606 
 607   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 608   static bool address_is_in_vm(address addr);
 609 
 610   // Loads .dll/.so and
 611   // in case of error it checks if .dll/.so was built for the
 612   // same architecture as HotSpot is running on
 613   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 614 
 615   // lookup symbol in a shared library
 616   static void* dll_lookup(void* handle, const char* name);
 617 
 618   // Unload library
 619   static void  dll_unload(void *lib);
 620 
 621   // Callback for loaded module information
 622   // Input parameters:
 623   //    char*     module_file_name,
 624   //    address   module_base_addr,
 625   //    address   module_top_addr,
 626   //    void*     param
 627   typedef int (*LoadedModulesCallbackFunc)(const char *, address, address, void *);
 628 
 629   static int get_loaded_modules_info(LoadedModulesCallbackFunc callback, void *param);
 630 
 631   // Return the handle of this process
 632   static void* get_default_process_handle();
 633 
 634   // Check for static linked agent library
 635   static bool find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 636                                  size_t syms_len);
 637 
 638   // Find agent entry point
 639   static void *find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 640                                    const char *syms[], size_t syms_len);
 641 
 642   // Provide C99 compliant versions of these functions, since some versions
 643   // of some platforms don't.
 644   static int vsnprintf(char* buf, size_t len, const char* fmt, va_list args) ATTRIBUTE_PRINTF(3, 0);
 645   static int snprintf(char* buf, size_t len, const char* fmt, ...) ATTRIBUTE_PRINTF(3, 4);
 646 
 647   // Get host name in buffer provided
 648   static bool get_host_name(char* buf, size_t buflen);
 649 
 650   // Print out system information; they are called by fatal error handler.
 651   // Output format may be different on different platforms.
 652   static void print_os_info(outputStream* st);
 653   static void print_os_info_brief(outputStream* st);
 654   static void print_cpu_info(outputStream* st, char* buf, size_t buflen);
 655   static void pd_print_cpu_info(outputStream* st, char* buf, size_t buflen);
 656   static void print_summary_info(outputStream* st, char* buf, size_t buflen);
 657   static void print_memory_info(outputStream* st);
 658   static void print_dll_info(outputStream* st);
 659   static void print_environment_variables(outputStream* st, const char** env_list);
 660   static void print_context(outputStream* st, const void* context);
 661   static void print_register_info(outputStream* st, const void* context);
 662   static void print_siginfo(outputStream* st, const void* siginfo);
 663   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 664   static void print_date_and_time(outputStream* st, char* buf, size_t buflen);
 665 
 666   static void print_location(outputStream* st, intptr_t x, bool verbose = false);
 667   static size_t lasterror(char *buf, size_t len);
 668   static int get_last_error();
 669 
 670   // Replacement for strerror().
 671   // Will return the english description of the error (e.g. "File not found", as
 672   //  suggested in the POSIX standard.
 673   // Will return "Unknown error" for an unknown errno value.
 674   // Will not attempt to localize the returned string.
 675   // Will always return a valid string which is a static constant.
 676   // Will not change the value of errno.
 677   static const char* strerror(int e);
 678 
 679   // Will return the literalized version of the given errno (e.g. "EINVAL"
 680   //  for EINVAL).
 681   // Will return "Unknown error" for an unknown errno value.
 682   // Will always return a valid string which is a static constant.
 683   // Will not change the value of errno.
 684   static const char* errno_name(int e);
 685 
 686   // Determines whether the calling process is being debugged by a user-mode debugger.
 687   static bool is_debugger_attached();
 688 
 689   // wait for a key press if PauseAtExit is set
 690   static void wait_for_keypress_at_exit(void);
 691 
 692   // The following two functions are used by fatal error handler to trace
 693   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 694   // frame.hpp/cpp assume thread is JavaThread, and also because different
 695   // OS/compiler may have different convention or provide different API to
 696   // walk C frames.
 697   //
 698   // We don't attempt to become a debugger, so we only follow frames if that
 699   // does not require a lookup in the unwind table, which is part of the binary
 700   // file but may be unsafe to read after a fatal error. So on x86, we can
 701   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 702   // possible to walk C stack without having the unwind table.
 703   static bool is_first_C_frame(frame *fr);
 704   static frame get_sender_for_C_frame(frame *fr);
 705 
 706   // return current frame. pc() and sp() are set to NULL on failure.
 707   static frame      current_frame();
 708 
 709   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 710 
 711   // returns a string to describe the exception/signal;
 712   // returns NULL if exception_code is not an OS exception/signal.
 713   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 714 
 715   // Returns the signal number (e.g. 11) for a given signal name (SIGSEGV).
 716   static int get_signal_number(const char* signal_name);
 717 
 718   // Returns native Java library, loads if necessary
 719   static void*    native_java_library();
 720 
 721   // Fills in path to jvm.dll/libjvm.so (used by the Disassembler)
 722   static void     jvm_path(char *buf, jint buflen);
 723 
 724   // JNI names
 725   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 726   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 727 
 728   // Init os specific system properties values
 729   static void init_system_properties_values();
 730 
 731   // IO operations, non-JVM_ version.
 732   static int stat(const char* path, struct stat* sbuf);
 733   static bool dir_is_empty(const char* path);
 734 
 735   // IO operations on binary files
 736   static int create_binary_file(const char* path, bool rewrite_existing);
 737   static jlong current_file_offset(int fd);
 738   static jlong seek_to_file_offset(int fd, jlong offset);
 739 
 740   // Retrieve native stack frames.
 741   // Parameter:
 742   //   stack:  an array to storage stack pointers.
 743   //   frames: size of above array.
 744   //   toSkip: number of stack frames to skip at the beginning.
 745   // Return: number of stack frames captured.
 746   static int get_native_stack(address* stack, int size, int toSkip = 0);
 747 
 748   // General allocation (must be MT-safe)
 749   static void* malloc  (size_t size, MEMFLAGS flags, const NativeCallStack& stack);
 750   static void* malloc  (size_t size, MEMFLAGS flags);
 751   static void* realloc (void *memblock, size_t size, MEMFLAGS flag, const NativeCallStack& stack);
 752   static void* realloc (void *memblock, size_t size, MEMFLAGS flag);
 753 
 754   static void  free    (void *memblock);
 755   static char* strdup(const char *, MEMFLAGS flags = mtInternal);  // Like strdup
 756   // Like strdup, but exit VM when strdup() returns NULL
 757   static char* strdup_check_oom(const char*, MEMFLAGS flags = mtInternal);
 758 
 759 #ifndef PRODUCT
 760   static julong num_mallocs;         // # of calls to malloc/realloc
 761   static julong alloc_bytes;         // # of bytes allocated
 762   static julong num_frees;           // # of calls to free
 763   static julong free_bytes;          // # of bytes freed
 764 #endif
 765 
 766   // SocketInterface (ex HPI SocketInterface )
 767   static int socket(int domain, int type, int protocol);
 768   static int socket_close(int fd);
 769   static int recv(int fd, char* buf, size_t nBytes, uint flags);
 770   static int send(int fd, char* buf, size_t nBytes, uint flags);
 771   static int raw_send(int fd, char* buf, size_t nBytes, uint flags);
 772   static int connect(int fd, struct sockaddr* him, socklen_t len);
 773   static struct hostent* get_host_by_name(char* name);
 774 
 775   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 776   static void  signal_init(TRAPS);
 777   static void  signal_init_pd();
 778   static void  signal_notify(int signal_number);
 779   static void* signal(int signal_number, void* handler);
 780   static void  signal_raise(int signal_number);
 781   static int   signal_wait();
 782   static void* user_handler();
 783   static void  terminate_signal_thread();
 784   static int   sigexitnum_pd();
 785 
 786   // random number generation
 787   static int random();                     // return 32bit pseudorandom number
 788   static void init_random(unsigned int initval);    // initialize random sequence
 789 
 790   // Structured OS Exception support
 791   static void os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread);
 792 
 793   // On Posix compatible OS it will simply check core dump limits while on Windows
 794   // it will check if dump file can be created. Check or prepare a core dump to be
 795   // taken at a later point in the same thread in os::abort(). Use the caller
 796   // provided buffer as a scratch buffer. The status message which will be written
 797   // into the error log either is file location or a short error message, depending
 798   // on the checking result.
 799   static void check_dump_limit(char* buffer, size_t bufferSize);
 800 
 801   // Get the default path to the core file
 802   // Returns the length of the string
 803   static int get_core_path(char* buffer, size_t bufferSize);
 804 
 805   // JVMTI & JVM monitoring and management support
 806   // The thread_cpu_time() and current_thread_cpu_time() are only
 807   // supported if is_thread_cpu_time_supported() returns true.
 808   // They are not supported on Solaris T1.
 809 
 810   // Thread CPU Time - return the fast estimate on a platform
 811   // On Solaris - call gethrvtime (fast) - user time only
 812   // On Linux   - fast clock_gettime where available - user+sys
 813   //            - otherwise: very slow /proc fs - user+sys
 814   // On Windows - GetThreadTimes - user+sys
 815   static jlong current_thread_cpu_time();
 816   static jlong thread_cpu_time(Thread* t);
 817 
 818   // Thread CPU Time with user_sys_cpu_time parameter.
 819   //
 820   // If user_sys_cpu_time is true, user+sys time is returned.
 821   // Otherwise, only user time is returned
 822   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 823   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 824 
 825   // Return a bunch of info about the timers.
 826   // Note that the returned info for these two functions may be different
 827   // on some platforms
 828   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 829   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 830 
 831   static bool is_thread_cpu_time_supported();
 832 
 833   // System loadavg support.  Returns -1 if load average cannot be obtained.
 834   static int loadavg(double loadavg[], int nelem);
 835 
 836   // Hook for os specific jvm options that we don't want to abort on seeing
 837   static bool obsolete_option(const JavaVMOption *option);
 838 
 839   // Amount beyond the callee frame size that we bang the stack.
 840   static int extra_bang_size_in_bytes();
 841 
 842   static char** split_path(const char* path, int* n);
 843 
 844   // Extensions
 845 #include "runtime/os_ext.hpp"
 846 
 847  public:
 848   class CrashProtectionCallback : public StackObj {
 849   public:
 850     virtual void call() = 0;
 851   };
 852 
 853   // Platform dependent stuff
 854 #ifndef _WINDOWS
 855 # include "os_posix.hpp"
 856 #endif
 857 #include OS_CPU_HEADER(os)
 858 #include OS_HEADER(os)
 859 
 860 #ifndef OS_NATIVE_THREAD_CREATION_FAILED_MSG
 861 #define OS_NATIVE_THREAD_CREATION_FAILED_MSG "unable to create native thread: possibly out of memory or process/resource limits reached"
 862 #endif
 863 
 864  public:
 865 #ifndef PLATFORM_PRINT_NATIVE_STACK
 866   // No platform-specific code for printing the native stack.
 867   static bool platform_print_native_stack(outputStream* st, const void* context,
 868                                           char *buf, int buf_size) {
 869     return false;
 870   }
 871 #endif
 872 
 873   // debugging support (mostly used by debug.cpp but also fatal error handler)
 874   static bool find(address pc, outputStream* st = tty); // OS specific function to make sense out of an address
 875 
 876   static bool dont_yield();                     // when true, JVM_Yield() is nop
 877   static void print_statistics();
 878 
 879   // Thread priority helpers (implemented in OS-specific part)
 880   static OSReturn set_native_priority(Thread* thread, int native_prio);
 881   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 882   static int java_to_os_priority[CriticalPriority + 1];
 883   // Hint to the underlying OS that a task switch would not be good.
 884   // Void return because it's a hint and can fail.
 885   static void hint_no_preempt();
 886   static const char* native_thread_creation_failed_msg() {
 887     return OS_NATIVE_THREAD_CREATION_FAILED_MSG;
 888   }
 889 
 890   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 891   // Causes the VM to wait until an external stimulus has been applied
 892   // (for Unix, that stimulus is a signal, for Windows, an external
 893   // ResumeThread call)
 894   static void pause();
 895 
 896   // Builds a platform dependent Agent_OnLoad_<libname> function name
 897   // which is used to find statically linked in agents.
 898   static char*  build_agent_function_name(const char *sym, const char *cname,
 899                                           bool is_absolute_path);
 900 
 901   class SuspendedThreadTaskContext {
 902   public:
 903     SuspendedThreadTaskContext(Thread* thread, void *ucontext) : _thread(thread), _ucontext(ucontext) {}
 904     Thread* thread() const { return _thread; }
 905     void* ucontext() const { return _ucontext; }
 906   private:
 907     Thread* _thread;
 908     void* _ucontext;
 909   };
 910 
 911   class SuspendedThreadTask {
 912   public:
 913     SuspendedThreadTask(Thread* thread) : _thread(thread), _done(false) {}
 914     void run();
 915     bool is_done() { return _done; }
 916     virtual void do_task(const SuspendedThreadTaskContext& context) = 0;
 917   protected:
 918     ~SuspendedThreadTask() {}
 919   private:
 920     void internal_do_task();
 921     Thread* _thread;
 922     bool _done;
 923   };
 924 
 925 #ifndef _WINDOWS
 926   // Suspend/resume support
 927   // Protocol:
 928   //
 929   // a thread starts in SR_RUNNING
 930   //
 931   // SR_RUNNING can go to
 932   //   * SR_SUSPEND_REQUEST when the WatcherThread wants to suspend it
 933   // SR_SUSPEND_REQUEST can go to
 934   //   * SR_RUNNING if WatcherThread decides it waited for SR_SUSPENDED too long (timeout)
 935   //   * SR_SUSPENDED if the stopped thread receives the signal and switches state
 936   // SR_SUSPENDED can go to
 937   //   * SR_WAKEUP_REQUEST when the WatcherThread has done the work and wants to resume
 938   // SR_WAKEUP_REQUEST can go to
 939   //   * SR_RUNNING when the stopped thread receives the signal
 940   //   * SR_WAKEUP_REQUEST on timeout (resend the signal and try again)
 941   class SuspendResume {
 942    public:
 943     enum State {
 944       SR_RUNNING,
 945       SR_SUSPEND_REQUEST,
 946       SR_SUSPENDED,
 947       SR_WAKEUP_REQUEST
 948     };
 949 
 950   private:
 951     volatile State _state;
 952 
 953   private:
 954     /* try to switch state from state "from" to state "to"
 955      * returns the state set after the method is complete
 956      */
 957     State switch_state(State from, State to);
 958 
 959   public:
 960     SuspendResume() : _state(SR_RUNNING) { }
 961 
 962     State state() const { return _state; }
 963 
 964     State request_suspend() {
 965       return switch_state(SR_RUNNING, SR_SUSPEND_REQUEST);
 966     }
 967 
 968     State cancel_suspend() {
 969       return switch_state(SR_SUSPEND_REQUEST, SR_RUNNING);
 970     }
 971 
 972     State suspended() {
 973       return switch_state(SR_SUSPEND_REQUEST, SR_SUSPENDED);
 974     }
 975 
 976     State request_wakeup() {
 977       return switch_state(SR_SUSPENDED, SR_WAKEUP_REQUEST);
 978     }
 979 
 980     State running() {
 981       return switch_state(SR_WAKEUP_REQUEST, SR_RUNNING);
 982     }
 983 
 984     bool is_running() const {
 985       return _state == SR_RUNNING;
 986     }
 987 
 988     bool is_suspend_request() const {
 989       return _state == SR_SUSPEND_REQUEST;
 990     }
 991 
 992     bool is_suspended() const {
 993       return _state == SR_SUSPENDED;
 994     }
 995   };
 996 #endif // !WINDOWS
 997 
 998 
 999  protected:
1000   static volatile unsigned int _rand_seed;    // seed for random number generator
1001   static int _processor_count;                // number of processors
1002   static int _initial_active_processor_count; // number of active processors during initialization.
1003 
1004   static char* format_boot_path(const char* format_string,
1005                                 const char* home,
1006                                 int home_len,
1007                                 char fileSep,
1008                                 char pathSep);
1009   static bool set_boot_path(char fileSep, char pathSep);
1010 
1011 };
1012 
1013 #ifndef _WINDOWS
1014 template<> struct IsRegisteredEnum<os::SuspendResume::State> : public TrueType {};
1015 #endif // !_WINDOWS
1016 
1017 // Note that "PAUSE" is almost always used with synchronization
1018 // so arguably we should provide Atomic::SpinPause() instead
1019 // of the global SpinPause() with C linkage.
1020 // It'd also be eligible for inlining on many platforms.
1021 
1022 extern "C" int SpinPause();
1023 
1024 #endif // SHARE_VM_RUNTIME_OS_HPP