1 /*
   2  * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_OS_HPP
  26 #define SHARE_VM_RUNTIME_OS_HPP
  27 
  28 #include "jvmtifiles/jvmti.h"
  29 #include "runtime/extendedPC.hpp"
  30 #include "runtime/handles.hpp"
  31 #include "utilities/top.hpp"
  32 #ifdef TARGET_OS_FAMILY_linux
  33 # include "jvm_linux.h"
  34 # include <setjmp.h>
  35 #endif
  36 #ifdef TARGET_OS_FAMILY_solaris
  37 # include "jvm_solaris.h"
  38 # include <setjmp.h>
  39 #endif
  40 #ifdef TARGET_OS_FAMILY_windows
  41 # include "jvm_windows.h"
  42 #endif
  43 #ifdef TARGET_OS_FAMILY_aix
  44 # include "jvm_aix.h"
  45 # include <setjmp.h>
  46 #endif
  47 #ifdef TARGET_OS_FAMILY_bsd
  48 # include "jvm_bsd.h"
  49 # include <setjmp.h>
  50 # ifdef __APPLE__
  51 #  include <mach/mach_time.h>
  52 # endif
  53 #endif
  54 
  55 class AgentLibrary;
  56 
  57 // os defines the interface to operating system; this includes traditional
  58 // OS services (time, I/O) as well as other functionality with system-
  59 // dependent code.
  60 
  61 typedef void (*dll_func)(...);
  62 
  63 class Thread;
  64 class JavaThread;
  65 class Event;
  66 class DLL;
  67 class FileHandle;
  68 class NativeCallStack;
  69 
  70 template<class E> class GrowableArray;
  71 
  72 // %%%%% Moved ThreadState, START_FN, OSThread to new osThread.hpp. -- Rose
  73 
  74 // Platform-independent error return values from OS functions
  75 enum OSReturn {
  76   OS_OK         =  0,        // Operation was successful
  77   OS_ERR        = -1,        // Operation failed
  78   OS_INTRPT     = -2,        // Operation was interrupted
  79   OS_TIMEOUT    = -3,        // Operation timed out
  80   OS_NOMEM      = -5,        // Operation failed for lack of memory
  81   OS_NORESOURCE = -6         // Operation failed for lack of nonmemory resource
  82 };
  83 
  84 enum ThreadPriority {        // JLS 20.20.1-3
  85   NoPriority       = -1,     // Initial non-priority value
  86   MinPriority      =  1,     // Minimum priority
  87   NormPriority     =  5,     // Normal (non-daemon) priority
  88   NearMaxPriority  =  9,     // High priority, used for VMThread
  89   MaxPriority      = 10,     // Highest priority, used for WatcherThread
  90                              // ensures that VMThread doesn't starve profiler
  91   CriticalPriority = 11      // Critical thread priority
  92 };
  93 
  94 // Executable parameter flag for os::commit_memory() and
  95 // os::commit_memory_or_exit().
  96 const bool ExecMem = true;
  97 
  98 // Typedef for structured exception handling support
  99 typedef void (*java_call_t)(JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
 100 
 101 class MallocTracker;
 102 
 103 class os: AllStatic {
 104   friend class VMStructs;
 105   friend class MallocTracker;
 106  public:
 107   enum { page_sizes_max = 9 }; // Size of _page_sizes array (8 plus a sentinel)
 108 
 109  private:
 110   static OSThread*          _starting_thread;
 111   static address            _polling_page;
 112   static volatile int32_t * _mem_serialize_page;
 113   static uintptr_t          _serialize_page_mask;
 114  public:
 115   static size_t             _page_sizes[page_sizes_max];
 116 
 117  private:
 118   static void init_page_sizes(size_t default_page_size) {
 119     _page_sizes[0] = default_page_size;
 120     _page_sizes[1] = 0; // sentinel
 121   }
 122 
 123   static char*  pd_reserve_memory(size_t bytes, char* addr = 0,
 124                                size_t alignment_hint = 0);
 125   static char*  pd_attempt_reserve_memory_at(size_t bytes, char* addr);
 126   static void   pd_split_reserved_memory(char *base, size_t size,
 127                                       size_t split, bool realloc);
 128   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
 129   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
 130                                  bool executable);
 131   // Same as pd_commit_memory() that either succeeds or calls
 132   // vm_exit_out_of_memory() with the specified mesg.
 133   static void   pd_commit_memory_or_exit(char* addr, size_t bytes,
 134                                          bool executable, const char* mesg);
 135   static void   pd_commit_memory_or_exit(char* addr, size_t size,
 136                                          size_t alignment_hint,
 137                                          bool executable, const char* mesg);
 138   static bool   pd_uncommit_memory(char* addr, size_t bytes);
 139   static bool   pd_release_memory(char* addr, size_t bytes);
 140 
 141   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
 142                            char *addr, size_t bytes, bool read_only = false,
 143                            bool allow_exec = false);
 144   static char*  pd_remap_memory(int fd, const char* file_name, size_t file_offset,
 145                              char *addr, size_t bytes, bool read_only,
 146                              bool allow_exec);
 147   static bool   pd_unmap_memory(char *addr, size_t bytes);
 148   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
 149   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 150 
 151   static size_t page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned);
 152 
 153  public:
 154   static void init(void);                      // Called before command line parsing
 155   static void init_before_ergo(void);          // Called after command line parsing
 156                                                // before VM ergonomics processing.
 157   static jint init_2(void);                    // Called after command line parsing
 158                                                // and VM ergonomics processing
 159   static void init_globals(void) {             // Called from init_globals() in init.cpp
 160     init_globals_ext();
 161   }
 162 
 163   // File names are case-insensitive on windows only
 164   // Override me as needed
 165   static int    file_name_strcmp(const char* s1, const char* s2);
 166 
 167   // unset environment variable
 168   static bool unsetenv(const char* name);
 169 
 170   static bool have_special_privileges();
 171 
 172   static jlong  javaTimeMillis();
 173   static jlong  javaTimeNanos();
 174   static void   javaTimeNanos_info(jvmtiTimerInfo *info_ptr);
 175   static void   javaTimeSystemUTC(jlong &seconds, jlong &nanos);
 176   static void   run_periodic_checks();
 177   static bool   supports_monotonic_clock();
 178 
 179   // Returns the elapsed time in seconds since the vm started.
 180   static double elapsedTime();
 181 
 182   // Returns real time in seconds since an arbitrary point
 183   // in the past.
 184   static bool getTimesSecs(double* process_real_time,
 185                            double* process_user_time,
 186                            double* process_system_time);
 187 
 188   // Interface to the performance counter
 189   static jlong elapsed_counter();
 190   static jlong elapsed_frequency();
 191 
 192   // The "virtual time" of a thread is the amount of time a thread has
 193   // actually run.  The first function indicates whether the OS supports
 194   // this functionality for the current thread, and if so:
 195   //   * the second enables vtime tracking (if that is required).
 196   //   * the third tells whether vtime is enabled.
 197   //   * the fourth returns the elapsed virtual time for the current
 198   //     thread.
 199   static bool supports_vtime();
 200   static bool enable_vtime();
 201   static bool vtime_enabled();
 202   static double elapsedVTime();
 203 
 204   // Return current local time in a string (YYYY-MM-DD HH:MM:SS).
 205   // It is MT safe, but not async-safe, as reading time zone
 206   // information may require a lock on some platforms.
 207   static char*      local_time_string(char *buf, size_t buflen);
 208   static struct tm* localtime_pd     (const time_t* clock, struct tm*  res);
 209   // Fill in buffer with current local time as an ISO-8601 string.
 210   // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
 211   // Returns buffer, or NULL if it failed.
 212   static char* iso8601_time(char* buffer, size_t buffer_length);
 213 
 214   // Interface for detecting multiprocessor system
 215   static inline bool is_MP() {
 216     // During bootstrap if _processor_count is not yet initialized
 217     // we claim to be MP as that is safest. If any platform has a
 218     // stub generator that might be triggered in this phase and for
 219     // which being declared MP when in fact not, is a problem - then
 220     // the bootstrap routine for the stub generator needs to check
 221     // the processor count directly and leave the bootstrap routine
 222     // in place until called after initialization has ocurred.
 223     return (_processor_count != 1) || AssumeMP;
 224   }
 225   static julong available_memory();
 226   static julong physical_memory();
 227   static bool has_allocatable_memory_limit(julong* limit);
 228   static bool is_server_class_machine();
 229 
 230   // number of CPUs
 231   static int processor_count() {
 232     return _processor_count;
 233   }
 234   static void set_processor_count(int count) { _processor_count = count; }
 235 
 236   // Returns the number of CPUs this process is currently allowed to run on.
 237   // Note that on some OSes this can change dynamically.
 238   static int active_processor_count();
 239 
 240   // Bind processes to processors.
 241   //     This is a two step procedure:
 242   //     first you generate a distribution of processes to processors,
 243   //     then you bind processes according to that distribution.
 244   // Compute a distribution for number of processes to processors.
 245   //    Stores the processor id's into the distribution array argument.
 246   //    Returns true if it worked, false if it didn't.
 247   static bool distribute_processes(uint length, uint* distribution);
 248   // Binds the current process to a processor.
 249   //    Returns true if it worked, false if it didn't.
 250   static bool bind_to_processor(uint processor_id);
 251 
 252   // Give a name to the current thread.
 253   static void set_native_thread_name(const char *name);
 254 
 255   // Interface for stack banging (predetect possible stack overflow for
 256   // exception processing)  There are guard pages, and above that shadow
 257   // pages for stack overflow checking.
 258   static bool uses_stack_guard_pages();
 259   static bool allocate_stack_guard_pages();
 260   static void bang_stack_shadow_pages();
 261   static bool stack_shadow_pages_available(Thread *thread, methodHandle method);
 262 
 263   // OS interface to Virtual Memory
 264 
 265   // Return the default page size.
 266   static int    vm_page_size();
 267 
 268   // Returns the page size to use for a region of memory.
 269   // region_size / min_pages will always be greater than or equal to the
 270   // returned value. The returned value will divide region_size.
 271   static size_t page_size_for_region_aligned(size_t region_size, size_t min_pages);
 272 
 273   // Returns the page size to use for a region of memory.
 274   // region_size / min_pages will always be greater than or equal to the
 275   // returned value. The returned value might not divide region_size.
 276   static size_t page_size_for_region_unaligned(size_t region_size, size_t min_pages);
 277 
 278   // Return the largest page size that can be used
 279   static size_t max_page_size() {
 280     // The _page_sizes array is sorted in descending order.
 281     return _page_sizes[0];
 282   }
 283 
 284   // Methods for tracing page sizes returned by the above method; enabled by
 285   // TracePageSizes.  The region_{min,max}_size parameters should be the values
 286   // passed to page_size_for_region() and page_size should be the result of that
 287   // call.  The (optional) base and size parameters should come from the
 288   // ReservedSpace base() and size() methods.
 289   static void trace_page_sizes(const char* str, const size_t* page_sizes,
 290                                int count) PRODUCT_RETURN;
 291   static void trace_page_sizes(const char* str, const size_t region_min_size,
 292                                const size_t region_max_size,
 293                                const size_t page_size,
 294                                const char* base = NULL,
 295                                const size_t size = 0) PRODUCT_RETURN;
 296 
 297   static int    vm_allocation_granularity();
 298   static char*  reserve_memory(size_t bytes, char* addr = 0,
 299                                size_t alignment_hint = 0);
 300   static char*  reserve_memory(size_t bytes, char* addr,
 301                                size_t alignment_hint, MEMFLAGS flags);
 302   static char*  reserve_memory_aligned(size_t size, size_t alignment);
 303   static char*  attempt_reserve_memory_at(size_t bytes, char* addr);
 304   static void   split_reserved_memory(char *base, size_t size,
 305                                       size_t split, bool realloc);
 306   static bool   commit_memory(char* addr, size_t bytes, bool executable);
 307   static bool   commit_memory(char* addr, size_t size, size_t alignment_hint,
 308                               bool executable);
 309   // Same as commit_memory() that either succeeds or calls
 310   // vm_exit_out_of_memory() with the specified mesg.
 311   static void   commit_memory_or_exit(char* addr, size_t bytes,
 312                                       bool executable, const char* mesg);
 313   static void   commit_memory_or_exit(char* addr, size_t size,
 314                                       size_t alignment_hint,
 315                                       bool executable, const char* mesg);
 316   static bool   uncommit_memory(char* addr, size_t bytes);
 317   static bool   release_memory(char* addr, size_t bytes);
 318 
 319   // Touch memory pages that cover the memory range from start to end (exclusive)
 320   // to make the OS back the memory range with actual memory.
 321   // Current implementation may not touch the last page if unaligned addresses
 322   // are passed.
 323   static void   pretouch_memory(char* start, char* end);
 324 
 325   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };
 326   static bool   protect_memory(char* addr, size_t bytes, ProtType prot,
 327                                bool is_committed = true);
 328 
 329   static bool   guard_memory(char* addr, size_t bytes);
 330   static bool   unguard_memory(char* addr, size_t bytes);
 331   static bool   create_stack_guard_pages(char* addr, size_t bytes);
 332   static bool   pd_create_stack_guard_pages(char* addr, size_t bytes);
 333   static bool   remove_stack_guard_pages(char* addr, size_t bytes);
 334 
 335   static char*  map_memory(int fd, const char* file_name, size_t file_offset,
 336                            char *addr, size_t bytes, bool read_only = false,
 337                            bool allow_exec = false);
 338   static char*  remap_memory(int fd, const char* file_name, size_t file_offset,
 339                              char *addr, size_t bytes, bool read_only,
 340                              bool allow_exec);
 341   static bool   unmap_memory(char *addr, size_t bytes);
 342   static void   free_memory(char *addr, size_t bytes, size_t alignment_hint);
 343   static void   realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 344 
 345   // NUMA-specific interface
 346   static bool   numa_has_static_binding();
 347   static bool   numa_has_group_homing();
 348   static void   numa_make_local(char *addr, size_t bytes, int lgrp_hint);
 349   static void   numa_make_global(char *addr, size_t bytes);
 350   static size_t numa_get_groups_num();
 351   static size_t numa_get_leaf_groups(int *ids, size_t size);
 352   static bool   numa_topology_changed();
 353   static int    numa_get_group_id();
 354 
 355   // Page manipulation
 356   struct page_info {
 357     size_t size;
 358     int lgrp_id;
 359   };
 360   static bool   get_page_info(char *start, page_info* info);
 361   static char*  scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found);
 362 
 363   static char*  non_memory_address_word();
 364   // reserve, commit and pin the entire memory region
 365   static char*  reserve_memory_special(size_t size, size_t alignment,
 366                                        char* addr, bool executable);
 367   static bool   release_memory_special(char* addr, size_t bytes);
 368   static void   large_page_init();
 369   static size_t large_page_size();
 370   static bool   can_commit_large_page_memory();
 371   static bool   can_execute_large_page_memory();
 372 
 373   // OS interface to polling page
 374   static address get_polling_page()             { return _polling_page; }
 375   static void    set_polling_page(address page) { _polling_page = page; }
 376   static bool    is_poll_address(address addr)  { return addr >= _polling_page && addr < (_polling_page + os::vm_page_size()); }
 377   static void    make_polling_page_unreadable();
 378   static void    make_polling_page_readable();
 379 
 380   // Routines used to serialize the thread state without using membars
 381   static void    serialize_thread_states();
 382 
 383   // Since we write to the serialize page from every thread, we
 384   // want stores to be on unique cache lines whenever possible
 385   // in order to minimize CPU cross talk.  We pre-compute the
 386   // amount to shift the thread* to make this offset unique to
 387   // each thread.
 388   static int     get_serialize_page_shift_count() {
 389     return SerializePageShiftCount;
 390   }
 391 
 392   static void     set_serialize_page_mask(uintptr_t mask) {
 393     _serialize_page_mask = mask;
 394   }
 395 
 396   static unsigned int  get_serialize_page_mask() {
 397     return _serialize_page_mask;
 398   }
 399 
 400   static void    set_memory_serialize_page(address page);
 401 
 402   static address get_memory_serialize_page() {
 403     return (address)_mem_serialize_page;
 404   }
 405 
 406   static inline void write_memory_serialize_page(JavaThread *thread) {
 407     uintptr_t page_offset = ((uintptr_t)thread >>
 408                             get_serialize_page_shift_count()) &
 409                             get_serialize_page_mask();
 410     *(volatile int32_t *)((uintptr_t)_mem_serialize_page+page_offset) = 1;
 411   }
 412 
 413   static bool    is_memory_serialize_page(JavaThread *thread, address addr) {
 414     if (UseMembar) return false;
 415     // Previously this function calculated the exact address of this
 416     // thread's serialize page, and checked if the faulting address
 417     // was equal.  However, some platforms mask off faulting addresses
 418     // to the page size, so now we just check that the address is
 419     // within the page.  This makes the thread argument unnecessary,
 420     // but we retain the NULL check to preserve existing behavior.
 421     if (thread == NULL) return false;
 422     address page = (address) _mem_serialize_page;
 423     return addr >= page && addr < (page + os::vm_page_size());
 424   }
 425 
 426   static void block_on_serialize_page_trap();
 427 
 428   // threads
 429 
 430   enum ThreadType {
 431     vm_thread,
 432     cgc_thread,        // Concurrent GC thread
 433     pgc_thread,        // Parallel GC thread
 434     java_thread,
 435     compiler_thread,
 436     watcher_thread,
 437     os_thread
 438   };
 439 
 440   static bool create_thread(Thread* thread,
 441                             ThreadType thr_type,
 442                             size_t stack_size = 0);
 443   static bool create_main_thread(JavaThread* thread);
 444   static bool create_attached_thread(JavaThread* thread);
 445   static void pd_start_thread(Thread* thread);
 446   static void start_thread(Thread* thread);
 447 
 448   static void initialize_thread(Thread* thr);
 449   static void free_thread(OSThread* osthread);
 450 
 451   // thread id on Linux/64bit is 64bit, on Windows and Solaris, it's 32bit
 452   static intx current_thread_id();
 453   static int current_process_id();
 454   static int sleep(Thread* thread, jlong ms, bool interruptable);
 455   // Short standalone OS sleep suitable for slow path spin loop.
 456   // Ignores Thread.interrupt() (so keep it short).
 457   // ms = 0, will sleep for the least amount of time allowed by the OS.
 458   static void naked_short_sleep(jlong ms);
 459   static void infinite_sleep(); // never returns, use with CAUTION
 460   static void naked_yield () ;
 461   static OSReturn set_priority(Thread* thread, ThreadPriority priority);
 462   static OSReturn get_priority(const Thread* const thread, ThreadPriority& priority);
 463 
 464   static void interrupt(Thread* thread);
 465   static bool is_interrupted(Thread* thread, bool clear_interrupted);
 466 
 467   static int pd_self_suspend_thread(Thread* thread);
 468 
 469   static ExtendedPC fetch_frame_from_context(void* ucVoid, intptr_t** sp, intptr_t** fp);
 470   static frame      fetch_frame_from_context(void* ucVoid);
 471 
 472   static ExtendedPC get_thread_pc(Thread *thread);
 473   static void breakpoint();
 474 
 475   static address current_stack_pointer();
 476   static address current_stack_base();
 477   static size_t current_stack_size();
 478 
 479   static void verify_stack_alignment() PRODUCT_RETURN;
 480 
 481   static int message_box(const char* title, const char* message);
 482   static char* do_you_want_to_debug(const char* message);
 483 
 484   // run cmd in a separate process and return its exit code; or -1 on failures
 485   static int fork_and_exec(char *cmd);
 486 
 487   // Call ::exit() on all platforms but Windows
 488   static void exit(int num);
 489 
 490   // Terminate the VM, but don't exit the process
 491   static void shutdown();
 492 
 493   // Terminate with an error.  Default is to generate a core file on platforms
 494   // that support such things.  This calls shutdown() and then aborts.
 495   static void abort(bool dump_core, void *siginfo, void *context);
 496   static void abort(bool dump_core = true);
 497 
 498   // Die immediately, no exit hook, no abort hook, no cleanup.
 499   static void die();
 500 
 501   // File i/o operations
 502   static const int default_file_open_flags();
 503   static int open(const char *path, int oflag, int mode);
 504   static FILE* open(int fd, const char* mode);
 505   static int close(int fd);
 506   static jlong lseek(int fd, jlong offset, int whence);
 507   static char* native_path(char *path);
 508   static int ftruncate(int fd, jlong length);
 509   static int fsync(int fd);
 510   static int available(int fd, jlong *bytes);
 511 
 512   //File i/o operations
 513 
 514   static size_t read(int fd, void *buf, unsigned int nBytes);
 515   static size_t read_at(int fd, void *buf, unsigned int nBytes, jlong offset);
 516   static size_t restartable_read(int fd, void *buf, unsigned int nBytes);
 517   static size_t write(int fd, const void *buf, unsigned int nBytes);
 518 
 519   // Reading directories.
 520   static DIR*           opendir(const char* dirname);
 521   static int            readdir_buf_size(const char *path);
 522   static struct dirent* readdir(DIR* dirp, dirent* dbuf);
 523   static int            closedir(DIR* dirp);
 524 
 525   // Dynamic library extension
 526   static const char*    dll_file_extension();
 527 
 528   static const char*    get_temp_directory();
 529   static const char*    get_current_directory(char *buf, size_t buflen);
 530 
 531   // Builds a platform-specific full library path given a ld path and lib name
 532   // Returns true if buffer contains full path to existing file, false otherwise
 533   static bool           dll_build_name(char* buffer, size_t size,
 534                                        const char* pathname, const char* fname);
 535 
 536   // Symbol lookup, find nearest function name; basically it implements
 537   // dladdr() for all platforms. Name of the nearest function is copied
 538   // to buf. Distance from its base address is optionally returned as offset.
 539   // If function name is not found, buf[0] is set to '\0' and offset is
 540   // set to -1 (if offset is non-NULL).
 541   static bool dll_address_to_function_name(address addr, char* buf,
 542                                            int buflen, int* offset,
 543                                            bool demangle = true);
 544 
 545   // Locate DLL/DSO. On success, full path of the library is copied to
 546   // buf, and offset is optionally set to be the distance between addr
 547   // and the library's base address. On failure, buf[0] is set to '\0'
 548   // and offset is set to -1 (if offset is non-NULL).
 549   static bool dll_address_to_library_name(address addr, char* buf,
 550                                           int buflen, int* offset);
 551 
 552   // Find out whether the pc is in the static code for jvm.dll/libjvm.so.
 553   static bool address_is_in_vm(address addr);
 554 
 555   // Loads .dll/.so and
 556   // in case of error it checks if .dll/.so was built for the
 557   // same architecture as HotSpot is running on
 558   static void* dll_load(const char *name, char *ebuf, int ebuflen);
 559 
 560   // lookup symbol in a shared library
 561   static void* dll_lookup(void* handle, const char* name);
 562 
 563   // Unload library
 564   static void  dll_unload(void *lib);
 565 
 566   // Callback for loaded module information
 567   // Input parameters:
 568   //    char*     module_file_name,
 569   //    address   module_base_addr,
 570   //    address   module_top_addr,
 571   //    void*     param
 572   typedef int (*LoadedModulesCallbackFunc)(const char *, address, address, void *);
 573 
 574   static int get_loaded_modules_info(LoadedModulesCallbackFunc callback, void *param);
 575 
 576   // Return the handle of this process
 577   static void* get_default_process_handle();
 578 
 579   // Check for static linked agent library
 580   static bool find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
 581                                  size_t syms_len);
 582 
 583   // Find agent entry point
 584   static void *find_agent_function(AgentLibrary *agent_lib, bool check_lib,
 585                                    const char *syms[], size_t syms_len);
 586 
 587   // Print out system information; they are called by fatal error handler.
 588   // Output format may be different on different platforms.
 589   static void print_os_info(outputStream* st);
 590   static void print_os_info_brief(outputStream* st);
 591   static void print_cpu_info(outputStream* st, char* buf, size_t buflen);
 592   static void pd_print_cpu_info(outputStream* st, char* buf, size_t buflen);
 593   static void print_memory_info(outputStream* st);
 594   static void print_dll_info(outputStream* st);
 595   static void print_environment_variables(outputStream* st, const char** env_list);
 596   static void print_context(outputStream* st, void* context);
 597   static void print_register_info(outputStream* st, void* context);
 598   static void print_siginfo(outputStream* st, void* siginfo);
 599   static void print_signal_handlers(outputStream* st, char* buf, size_t buflen);
 600   static void print_date_and_time(outputStream* st, char* buf, size_t buflen);
 601 
 602   static void print_location(outputStream* st, intptr_t x, bool verbose = false);
 603   static size_t lasterror(char *buf, size_t len);
 604   static int get_last_error();
 605 
 606   // Determines whether the calling process is being debugged by a user-mode debugger.
 607   static bool is_debugger_attached();
 608 
 609   // wait for a key press if PauseAtExit is set
 610   static void wait_for_keypress_at_exit(void);
 611 
 612   // The following two functions are used by fatal error handler to trace
 613   // native (C) frames. They are not part of frame.hpp/frame.cpp because
 614   // frame.hpp/cpp assume thread is JavaThread, and also because different
 615   // OS/compiler may have different convention or provide different API to
 616   // walk C frames.
 617   //
 618   // We don't attempt to become a debugger, so we only follow frames if that
 619   // does not require a lookup in the unwind table, which is part of the binary
 620   // file but may be unsafe to read after a fatal error. So on x86, we can
 621   // only walk stack if %ebp is used as frame pointer; on ia64, it's not
 622   // possible to walk C stack without having the unwind table.
 623   static bool is_first_C_frame(frame *fr);
 624   static frame get_sender_for_C_frame(frame *fr);
 625 
 626   // return current frame. pc() and sp() are set to NULL on failure.
 627   static frame      current_frame();
 628 
 629   static void print_hex_dump(outputStream* st, address start, address end, int unitsize);
 630 
 631   // returns a string to describe the exception/signal;
 632   // returns NULL if exception_code is not an OS exception/signal.
 633   static const char* exception_name(int exception_code, char* buf, size_t buflen);
 634 
 635   // Returns native Java library, loads if necessary
 636   static void*    native_java_library();
 637 
 638   // Fills in path to jvm.dll/libjvm.so (used by the Disassembler)
 639   static void     jvm_path(char *buf, jint buflen);
 640 
 641   // Returns true if we are running in a headless jre.
 642   static bool     is_headless_jre();
 643 
 644   // JNI names
 645   static void     print_jni_name_prefix_on(outputStream* st, int args_size);
 646   static void     print_jni_name_suffix_on(outputStream* st, int args_size);
 647 
 648   // Init os specific system properties values
 649   static void init_system_properties_values();
 650 
 651   // IO operations, non-JVM_ version.
 652   static int stat(const char* path, struct stat* sbuf);
 653   static bool dir_is_empty(const char* path);
 654 
 655   // IO operations on binary files
 656   static int create_binary_file(const char* path, bool rewrite_existing);
 657   static jlong current_file_offset(int fd);
 658   static jlong seek_to_file_offset(int fd, jlong offset);
 659 
 660   // Thread Local Storage
 661   static int   allocate_thread_local_storage();
 662   static void  thread_local_storage_at_put(int index, void* value);
 663   static void* thread_local_storage_at(int index);
 664   static void  free_thread_local_storage(int index);
 665 
 666   // Retrieve native stack frames.
 667   // Parameter:
 668   //   stack:  an array to storage stack pointers.
 669   //   frames: size of above array.
 670   //   toSkip: number of stack frames to skip at the beginning.
 671   // Return: number of stack frames captured.
 672   static int get_native_stack(address* stack, int size, int toSkip = 0);
 673 
 674   // General allocation (must be MT-safe)
 675   static void* malloc  (size_t size, MEMFLAGS flags, const NativeCallStack& stack);
 676   static void* malloc  (size_t size, MEMFLAGS flags);
 677   static void* realloc (void *memblock, size_t size, MEMFLAGS flag, const NativeCallStack& stack);
 678   static void* realloc (void *memblock, size_t size, MEMFLAGS flag);
 679 
 680   static void  free    (void *memblock);
 681   static bool  check_heap(bool force = false);      // verify C heap integrity
 682   static char* strdup(const char *, MEMFLAGS flags = mtInternal);  // Like strdup
 683   // Like strdup, but exit VM when strdup() returns NULL
 684   static char* strdup_check_oom(const char*, MEMFLAGS flags = mtInternal);
 685 
 686 #ifndef PRODUCT
 687   static julong num_mallocs;         // # of calls to malloc/realloc
 688   static julong alloc_bytes;         // # of bytes allocated
 689   static julong num_frees;           // # of calls to free
 690   static julong free_bytes;          // # of bytes freed
 691 #endif
 692 
 693   // SocketInterface (ex HPI SocketInterface )
 694   static int socket(int domain, int type, int protocol);
 695   static int socket_close(int fd);
 696   static int recv(int fd, char* buf, size_t nBytes, uint flags);
 697   static int send(int fd, char* buf, size_t nBytes, uint flags);
 698   static int raw_send(int fd, char* buf, size_t nBytes, uint flags);
 699   static int connect(int fd, struct sockaddr* him, socklen_t len);
 700   static struct hostent* get_host_by_name(char* name);
 701 
 702   // Support for signals (see JVM_RaiseSignal, JVM_RegisterSignal)
 703   static void  signal_init();
 704   static void  signal_init_pd();
 705   static void  signal_notify(int signal_number);
 706   static void* signal(int signal_number, void* handler);
 707   static void  signal_raise(int signal_number);
 708   static int   signal_wait();
 709   static int   signal_lookup();
 710   static void* user_handler();
 711   static void  terminate_signal_thread();
 712   static int   sigexitnum_pd();
 713 
 714   // random number generation
 715   static long random();                    // return 32bit pseudorandom number
 716   static void init_random(long initval);   // initialize random sequence
 717 
 718   // Structured OS Exception support
 719   static void os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method, JavaCallArguments* args, Thread* thread);
 720 
 721   // On Posix compatible OS it will simply check core dump limits while on Windows
 722   // it will check if dump file can be created. Check or prepare a core dump to be
 723   // taken at a later point in the same thread in os::abort(). Use the caller
 724   // provided buffer as a scratch buffer. The status message which will be written
 725   // into the error log either is file location or a short error message, depending
 726   // on the checking result.
 727   static void check_dump_limit(char* buffer, size_t bufferSize);
 728 
 729   // Get the default path to the core file
 730   // Returns the length of the string
 731   static int get_core_path(char* buffer, size_t bufferSize);
 732 
 733   // JVMTI & JVM monitoring and management support
 734   // The thread_cpu_time() and current_thread_cpu_time() are only
 735   // supported if is_thread_cpu_time_supported() returns true.
 736   // They are not supported on Solaris T1.
 737 
 738   // Thread CPU Time - return the fast estimate on a platform
 739   // On Solaris - call gethrvtime (fast) - user time only
 740   // On Linux   - fast clock_gettime where available - user+sys
 741   //            - otherwise: very slow /proc fs - user+sys
 742   // On Windows - GetThreadTimes - user+sys
 743   static jlong current_thread_cpu_time();
 744   static jlong thread_cpu_time(Thread* t);
 745 
 746   // Thread CPU Time with user_sys_cpu_time parameter.
 747   //
 748   // If user_sys_cpu_time is true, user+sys time is returned.
 749   // Otherwise, only user time is returned
 750   static jlong current_thread_cpu_time(bool user_sys_cpu_time);
 751   static jlong thread_cpu_time(Thread* t, bool user_sys_cpu_time);
 752 
 753   // Return a bunch of info about the timers.
 754   // Note that the returned info for these two functions may be different
 755   // on some platforms
 756   static void current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 757   static void thread_cpu_time_info(jvmtiTimerInfo *info_ptr);
 758 
 759   static bool is_thread_cpu_time_supported();
 760 
 761   // System loadavg support.  Returns -1 if load average cannot be obtained.
 762   static int loadavg(double loadavg[], int nelem);
 763 
 764   // Hook for os specific jvm options that we don't want to abort on seeing
 765   static bool obsolete_option(const JavaVMOption *option);
 766 
 767   // Amount beyond the callee frame size that we bang the stack.
 768   static int extra_bang_size_in_bytes();
 769 
 770   // Extensions
 771 #include "runtime/os_ext.hpp"
 772 
 773  public:
 774   class CrashProtectionCallback : public StackObj {
 775   public:
 776     virtual void call() = 0;
 777   };
 778 
 779   // Platform dependent stuff
 780 #ifdef TARGET_OS_FAMILY_linux
 781 # include "os_linux.hpp"
 782 # include "os_posix.hpp"
 783 #endif
 784 #ifdef TARGET_OS_FAMILY_solaris
 785 # include "os_solaris.hpp"
 786 # include "os_posix.hpp"
 787 #endif
 788 #ifdef TARGET_OS_FAMILY_windows
 789 # include "os_windows.hpp"
 790 #endif
 791 #ifdef TARGET_OS_FAMILY_aix
 792 # include "os_aix.hpp"
 793 # include "os_posix.hpp"
 794 #endif
 795 #ifdef TARGET_OS_FAMILY_bsd
 796 # include "os_posix.hpp"
 797 # include "os_bsd.hpp"
 798 #endif
 799 #ifdef TARGET_OS_ARCH_linux_x86
 800 # include "os_linux_x86.hpp"
 801 #endif
 802 #ifdef TARGET_OS_ARCH_linux_sparc
 803 # include "os_linux_sparc.hpp"
 804 #endif
 805 #ifdef TARGET_OS_ARCH_linux_zero
 806 # include "os_linux_zero.hpp"
 807 #endif
 808 #ifdef TARGET_OS_ARCH_solaris_x86
 809 # include "os_solaris_x86.hpp"
 810 #endif
 811 #ifdef TARGET_OS_ARCH_solaris_sparc
 812 # include "os_solaris_sparc.hpp"
 813 #endif
 814 #ifdef TARGET_OS_ARCH_windows_x86
 815 # include "os_windows_x86.hpp"
 816 #endif
 817 #ifdef TARGET_OS_ARCH_linux_arm
 818 # include "os_linux_arm.hpp"
 819 #endif
 820 #ifdef TARGET_OS_ARCH_linux_ppc
 821 # include "os_linux_ppc.hpp"
 822 #endif
 823 #ifdef TARGET_OS_ARCH_aix_ppc
 824 # include "os_aix_ppc.hpp"
 825 #endif
 826 #ifdef TARGET_OS_ARCH_linux_aarch64
 827 # include "os_linux_aarch64.hpp"
 828 #endif
 829 #ifdef TARGET_OS_ARCH_bsd_x86
 830 # include "os_bsd_x86.hpp"
 831 #endif
 832 #ifdef TARGET_OS_ARCH_bsd_zero
 833 # include "os_bsd_zero.hpp"
 834 #endif
 835 
 836 #ifndef OS_NATIVE_THREAD_CREATION_FAILED_MSG
 837 #define OS_NATIVE_THREAD_CREATION_FAILED_MSG "unable to create native thread: possibly out of memory or process/resource limits reached"
 838 #endif
 839 
 840  public:
 841 #ifndef PLATFORM_PRINT_NATIVE_STACK
 842   // No platform-specific code for printing the native stack.
 843   static bool platform_print_native_stack(outputStream* st, void* context,
 844                                           char *buf, int buf_size) {
 845     return false;
 846   }
 847 #endif
 848 
 849   // debugging support (mostly used by debug.cpp but also fatal error handler)
 850   static bool find(address pc, outputStream* st = tty); // OS specific function to make sense out of an address
 851 
 852   static bool dont_yield();                     // when true, JVM_Yield() is nop
 853   static void print_statistics();
 854 
 855   // Thread priority helpers (implemented in OS-specific part)
 856   static OSReturn set_native_priority(Thread* thread, int native_prio);
 857   static OSReturn get_native_priority(const Thread* const thread, int* priority_ptr);
 858   static int java_to_os_priority[CriticalPriority + 1];
 859   // Hint to the underlying OS that a task switch would not be good.
 860   // Void return because it's a hint and can fail.
 861   static void hint_no_preempt();
 862   static const char* native_thread_creation_failed_msg() {
 863     return OS_NATIVE_THREAD_CREATION_FAILED_MSG;
 864   }
 865 
 866   // Used at creation if requested by the diagnostic flag PauseAtStartup.
 867   // Causes the VM to wait until an external stimulus has been applied
 868   // (for Unix, that stimulus is a signal, for Windows, an external
 869   // ResumeThread call)
 870   static void pause();
 871 
 872   // Builds a platform dependent Agent_OnLoad_<libname> function name
 873   // which is used to find statically linked in agents.
 874   static char*  build_agent_function_name(const char *sym, const char *cname,
 875                                           bool is_absolute_path);
 876 
 877   class SuspendedThreadTaskContext {
 878   public:
 879     SuspendedThreadTaskContext(Thread* thread, void *ucontext) : _thread(thread), _ucontext(ucontext) {}
 880     Thread* thread() const { return _thread; }
 881     void* ucontext() const { return _ucontext; }
 882   private:
 883     Thread* _thread;
 884     void* _ucontext;
 885   };
 886 
 887   class SuspendedThreadTask {
 888   public:
 889     SuspendedThreadTask(Thread* thread) : _thread(thread), _done(false) {}
 890     virtual ~SuspendedThreadTask() {}
 891     void run();
 892     bool is_done() { return _done; }
 893     virtual void do_task(const SuspendedThreadTaskContext& context) = 0;
 894   protected:
 895   private:
 896     void internal_do_task();
 897     Thread* _thread;
 898     bool _done;
 899   };
 900 
 901 #ifndef TARGET_OS_FAMILY_windows
 902   // Suspend/resume support
 903   // Protocol:
 904   //
 905   // a thread starts in SR_RUNNING
 906   //
 907   // SR_RUNNING can go to
 908   //   * SR_SUSPEND_REQUEST when the WatcherThread wants to suspend it
 909   // SR_SUSPEND_REQUEST can go to
 910   //   * SR_RUNNING if WatcherThread decides it waited for SR_SUSPENDED too long (timeout)
 911   //   * SR_SUSPENDED if the stopped thread receives the signal and switches state
 912   // SR_SUSPENDED can go to
 913   //   * SR_WAKEUP_REQUEST when the WatcherThread has done the work and wants to resume
 914   // SR_WAKEUP_REQUEST can go to
 915   //   * SR_RUNNING when the stopped thread receives the signal
 916   //   * SR_WAKEUP_REQUEST on timeout (resend the signal and try again)
 917   class SuspendResume {
 918    public:
 919     enum State {
 920       SR_RUNNING,
 921       SR_SUSPEND_REQUEST,
 922       SR_SUSPENDED,
 923       SR_WAKEUP_REQUEST
 924     };
 925 
 926   private:
 927     volatile State _state;
 928 
 929   private:
 930     /* try to switch state from state "from" to state "to"
 931      * returns the state set after the method is complete
 932      */
 933     State switch_state(State from, State to);
 934 
 935   public:
 936     SuspendResume() : _state(SR_RUNNING) { }
 937 
 938     State state() const { return _state; }
 939 
 940     State request_suspend() {
 941       return switch_state(SR_RUNNING, SR_SUSPEND_REQUEST);
 942     }
 943 
 944     State cancel_suspend() {
 945       return switch_state(SR_SUSPEND_REQUEST, SR_RUNNING);
 946     }
 947 
 948     State suspended() {
 949       return switch_state(SR_SUSPEND_REQUEST, SR_SUSPENDED);
 950     }
 951 
 952     State request_wakeup() {
 953       return switch_state(SR_SUSPENDED, SR_WAKEUP_REQUEST);
 954     }
 955 
 956     State running() {
 957       return switch_state(SR_WAKEUP_REQUEST, SR_RUNNING);
 958     }
 959 
 960     bool is_running() const {
 961       return _state == SR_RUNNING;
 962     }
 963 
 964     bool is_suspend_request() const {
 965       return _state == SR_SUSPEND_REQUEST;
 966     }
 967 
 968     bool is_suspended() const {
 969       return _state == SR_SUSPENDED;
 970     }
 971   };
 972 #endif
 973 
 974 
 975  protected:
 976   static long _rand_seed;                   // seed for random number generator
 977   static int _processor_count;              // number of processors
 978 
 979   static char* format_boot_path(const char* format_string,
 980                                 const char* home,
 981                                 int home_len,
 982                                 char fileSep,
 983                                 char pathSep);
 984   static bool set_boot_path(char fileSep, char pathSep);
 985   static char** split_path(const char* path, int* n);
 986 
 987 };
 988 
 989 // Note that "PAUSE" is almost always used with synchronization
 990 // so arguably we should provide Atomic::SpinPause() instead
 991 // of the global SpinPause() with C linkage.
 992 // It'd also be eligible for inlining on many platforms.
 993 
 994 extern "C" int SpinPause();
 995 
 996 #endif // SHARE_VM_RUNTIME_OS_HPP