1 /*
   2  * Copyright (c) 1999, 2020, 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 // no precompiled headers
  26 #include "jvm.h"
  27 #include "asm/macroAssembler.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "code/vtableStubs.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "memory/allocation.inline.hpp"
  35 #include "memory/resourceArea.hpp"
  36 #include "nativeInst_x86.hpp"
  37 #include "os_share_windows.hpp"
  38 #include "prims/jniFastGetField.hpp"
  39 #include "prims/jvm_misc.hpp"
  40 #include "runtime/arguments.hpp"
  41 #include "runtime/frame.inline.hpp"
  42 #include "runtime/interfaceSupport.inline.hpp"
  43 #include "runtime/java.hpp"
  44 #include "runtime/javaCalls.hpp"
  45 #include "runtime/mutexLocker.hpp"
  46 #include "runtime/osThread.hpp"
  47 #include "runtime/sharedRuntime.hpp"
  48 #include "runtime/stubRoutines.hpp"
  49 #include "runtime/thread.inline.hpp"
  50 #include "runtime/timer.hpp"
  51 #include "symbolengine.hpp"
  52 #include "unwind_windows_x86.hpp"
  53 #include "utilities/events.hpp"
  54 #include "utilities/vmError.hpp"
  55 #include "windbghelp.hpp"
  56 
  57 
  58 #undef REG_SP
  59 #undef REG_FP
  60 #undef REG_PC
  61 #ifdef AMD64
  62 #define REG_SP Rsp
  63 #define REG_FP Rbp
  64 #define REG_PC Rip
  65 #else
  66 #define REG_SP Esp
  67 #define REG_FP Ebp
  68 #define REG_PC Eip
  69 #endif // AMD64
  70 
  71 extern LONG WINAPI topLevelExceptionFilter(_EXCEPTION_POINTERS* );
  72 
  73 // Install a win32 structured exception handler around thread.
  74 void os::os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread) {
  75   __try {
  76 
  77 #ifndef AMD64
  78     // We store the current thread in this wrapperthread location
  79     // and determine how far away this address is from the structured
  80     // execption pointer that FS:[0] points to.  This get_thread
  81     // code can then get the thread pointer via FS.
  82     //
  83     // Warning:  This routine must NEVER be inlined since we'd end up with
  84     //           multiple offsets.
  85     //
  86     volatile Thread* wrapperthread = thread;
  87 
  88     if (os::win32::get_thread_ptr_offset() == 0) {
  89       int thread_ptr_offset;
  90       __asm {
  91         lea eax, dword ptr wrapperthread;
  92         sub eax, dword ptr FS:[0H];
  93         mov thread_ptr_offset, eax
  94       };
  95       os::win32::set_thread_ptr_offset(thread_ptr_offset);
  96     }
  97 #ifdef ASSERT
  98     // Verify that the offset hasn't changed since we initally captured
  99     // it. This might happen if we accidentally ended up with an
 100     // inlined version of this routine.
 101     else {
 102       int test_thread_ptr_offset;
 103       __asm {
 104         lea eax, dword ptr wrapperthread;
 105         sub eax, dword ptr FS:[0H];
 106         mov test_thread_ptr_offset, eax
 107       };
 108       assert(test_thread_ptr_offset == os::win32::get_thread_ptr_offset(),
 109              "thread pointer offset from SEH changed");
 110     }
 111 #endif // ASSERT
 112 #endif // !AMD64
 113 
 114     f(value, method, args, thread);
 115   } __except(topLevelExceptionFilter((_EXCEPTION_POINTERS*)_exception_info())) {
 116       // Nothing to do.
 117   }
 118 }
 119 
 120 #ifdef AMD64
 121 
 122 // This is the language specific handler for exceptions
 123 // originating from dynamically generated code.
 124 // We call the standard structured exception handler
 125 // We only expect Continued Execution since we cannot unwind
 126 // from generated code.
 127 LONG HandleExceptionFromCodeCache(
 128   IN PEXCEPTION_RECORD ExceptionRecord,
 129   IN ULONG64 EstablisherFrame,
 130   IN OUT PCONTEXT ContextRecord,
 131   IN OUT PDISPATCHER_CONTEXT DispatcherContext) {
 132   EXCEPTION_POINTERS ep;
 133   LONG result;
 134 
 135   ep.ExceptionRecord = ExceptionRecord;
 136   ep.ContextRecord = ContextRecord;
 137 
 138   result = topLevelExceptionFilter(&ep);
 139 
 140   // We better only get a CONTINUE_EXECUTION from our handler
 141   // since we don't have unwind information registered.
 142 
 143   guarantee( result == EXCEPTION_CONTINUE_EXECUTION,
 144              "Unexpected result from topLevelExceptionFilter");
 145 
 146   return(ExceptionContinueExecution);
 147 }
 148 
 149 
 150 // Structure containing the Windows Data Structures required
 151 // to register our Code Cache exception handler.
 152 // We put these in the CodeCache since the API requires
 153 // all addresses in these structures are relative to the Code
 154 // area registered with RtlAddFunctionTable.
 155 typedef struct {
 156   char ExceptionHandlerInstr[16];  // jmp HandleExceptionFromCodeCache
 157   RUNTIME_FUNCTION rt;
 158   UNWIND_INFO_EH_ONLY unw;
 159 } DynamicCodeData, *pDynamicCodeData;
 160 
 161 #endif // AMD64
 162 //
 163 // Register our CodeCache area with the OS so it will dispatch exceptions
 164 // to our topLevelExceptionFilter when we take an exception in our
 165 // dynamically generated code.
 166 //
 167 // Arguments:  low and high are the address of the full reserved
 168 // codeCache area
 169 //
 170 bool os::register_code_area(char *low, char *high) {
 171 #ifdef AMD64
 172 
 173   ResourceMark rm;
 174 
 175   pDynamicCodeData pDCD;
 176   PRUNTIME_FUNCTION prt;
 177   PUNWIND_INFO_EH_ONLY punwind;
 178 
 179   BufferBlob* blob = BufferBlob::create("CodeCache Exception Handler", sizeof(DynamicCodeData));
 180   CodeBuffer cb(blob);
 181   MacroAssembler* masm = new MacroAssembler(&cb);
 182   pDCD = (pDynamicCodeData) masm->pc();
 183 
 184   masm->jump(ExternalAddress((address)&HandleExceptionFromCodeCache));
 185   masm->flush();
 186 
 187   // Create an Unwind Structure specifying no unwind info
 188   // other than an Exception Handler
 189   punwind = &pDCD->unw;
 190   punwind->Version = 1;
 191   punwind->Flags = UNW_FLAG_EHANDLER;
 192   punwind->SizeOfProlog = 0;
 193   punwind->CountOfCodes = 0;
 194   punwind->FrameRegister = 0;
 195   punwind->FrameOffset = 0;
 196   punwind->ExceptionHandler = (char *)(&(pDCD->ExceptionHandlerInstr[0])) -
 197                               (char*)low;
 198   punwind->ExceptionData[0] = 0;
 199 
 200   // This structure describes the covered dynamic code area.
 201   // Addresses are relative to the beginning on the code cache area
 202   prt = &pDCD->rt;
 203   prt->BeginAddress = 0;
 204   prt->EndAddress = (ULONG)(high - low);
 205   prt->UnwindData = ((char *)punwind - low);
 206 
 207   guarantee(RtlAddFunctionTable(prt, 1, (ULONGLONG)low),
 208             "Failed to register Dynamic Code Exception Handler with RtlAddFunctionTable");
 209 
 210 #endif // AMD64
 211   return true;
 212 }
 213 
 214 #ifdef AMD64
 215 /*
 216  * Windows/x64 does not use stack frames the way expected by Java:
 217  * [1] in most cases, there is no frame pointer. All locals are addressed via RSP
 218  * [2] in rare cases, when alloca() is used, a frame pointer is used, but this may
 219  *     not be RBP.
 220  * See http://msdn.microsoft.com/en-us/library/ew5tede7.aspx
 221  *
 222  * So it's not possible to print the native stack using the
 223  *     while (...) {...  fr = os::get_sender_for_C_frame(&fr); }
 224  * loop in vmError.cpp. We need to roll our own loop.
 225  */
 226 bool os::platform_print_native_stack(outputStream* st, const void* context,
 227                                      char *buf, int buf_size)
 228 {
 229   CONTEXT ctx;
 230   if (context != NULL) {
 231     memcpy(&ctx, context, sizeof(ctx));
 232   } else {
 233     RtlCaptureContext(&ctx);
 234   }
 235 
 236   st->print_cr("Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)");
 237 
 238   STACKFRAME stk;
 239   memset(&stk, 0, sizeof(stk));
 240   stk.AddrStack.Offset    = ctx.Rsp;
 241   stk.AddrStack.Mode      = AddrModeFlat;
 242   stk.AddrFrame.Offset    = ctx.Rbp;
 243   stk.AddrFrame.Mode      = AddrModeFlat;
 244   stk.AddrPC.Offset       = ctx.Rip;
 245   stk.AddrPC.Mode         = AddrModeFlat;
 246 
 247   int count = 0;
 248   address lastpc = 0;
 249   while (count++ < StackPrintLimit) {
 250     intptr_t* sp = (intptr_t*)stk.AddrStack.Offset;
 251     intptr_t* fp = (intptr_t*)stk.AddrFrame.Offset; // NOT necessarily the same as ctx.Rbp!
 252     address pc = (address)stk.AddrPC.Offset;
 253 
 254     if (pc != NULL) {
 255       if (count == 2 && lastpc == pc) {
 256         // Skip it -- StackWalk64() may return the same PC
 257         // (but different SP) on the first try.
 258       } else {
 259         // Don't try to create a frame(sp, fp, pc) -- on WinX64, stk.AddrFrame
 260         // may not contain what Java expects, and may cause the frame() constructor
 261         // to crash. Let's just print out the symbolic address.
 262         frame::print_C_frame(st, buf, buf_size, pc);
 263         // print source file and line, if available
 264         char buf[128];
 265         int line_no;
 266         if (SymbolEngine::get_source_info(pc, buf, sizeof(buf), &line_no)) {
 267           st->print("  (%s:%d)", buf, line_no);
 268         }
 269         st->cr();
 270       }
 271       lastpc = pc;
 272     }
 273 
 274     PVOID p = WindowsDbgHelp::symFunctionTableAccess64(GetCurrentProcess(), stk.AddrPC.Offset);
 275     if (!p) {
 276       // StackWalk64() can't handle this PC. Calling StackWalk64 again may cause crash.
 277       break;
 278     }
 279 
 280     BOOL result = WindowsDbgHelp::stackWalk64(
 281         IMAGE_FILE_MACHINE_AMD64,  // __in      DWORD MachineType,
 282         GetCurrentProcess(),       // __in      HANDLE hProcess,
 283         GetCurrentThread(),        // __in      HANDLE hThread,
 284         &stk,                      // __inout   LP STACKFRAME64 StackFrame,
 285         &ctx);                     // __inout   PVOID ContextRecord,
 286 
 287     if (!result) {
 288       break;
 289     }
 290   }
 291   if (count > StackPrintLimit) {
 292     st->print_cr("...<more frames>...");
 293   }
 294   st->cr();
 295 
 296   return true;
 297 }
 298 #endif // AMD64
 299 
 300 address os::fetch_frame_from_context(const void* ucVoid,
 301                     intptr_t** ret_sp, intptr_t** ret_fp) {
 302 
 303   address  epc;
 304   CONTEXT* uc = (CONTEXT*)ucVoid;
 305 
 306   if (uc != NULL) {
 307     epc = (address)uc->REG_PC;
 308     if (ret_sp) *ret_sp = (intptr_t*)uc->REG_SP;
 309     if (ret_fp) *ret_fp = (intptr_t*)uc->REG_FP;
 310   } else {
 311     epc = NULL;
 312     if (ret_sp) *ret_sp = (intptr_t *)NULL;
 313     if (ret_fp) *ret_fp = (intptr_t *)NULL;
 314   }
 315 
 316   return epc;
 317 }
 318 
 319 frame os::fetch_frame_from_context(const void* ucVoid) {
 320   intptr_t* sp;
 321   intptr_t* fp;
 322   address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 323   return frame(sp, fp, epc);
 324 }
 325 
 326 // VC++ does not save frame pointer on stack in optimized build. It
 327 // can be turned off by /Oy-. If we really want to walk C frames,
 328 // we can use the StackWalk() API.
 329 frame os::get_sender_for_C_frame(frame* fr) {
 330   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
 331 }
 332 
 333 #ifndef AMD64
 334 // Ignore "C4172: returning address of local variable or temporary" on 32bit
 335 PRAGMA_DIAG_PUSH
 336 PRAGMA_DISABLE_MSVC_WARNING(4172)
 337 // Returns an estimate of the current stack pointer. Result must be guaranteed
 338 // to point into the calling threads stack, and be no lower than the current
 339 // stack pointer.
 340 address os::current_stack_pointer() {
 341   int dummy;
 342   address sp = (address)&dummy;
 343   return sp;
 344 }
 345 PRAGMA_DIAG_POP
 346 #else
 347 // Returns the current stack pointer. Accurate value needed for
 348 // os::verify_stack_alignment().
 349 address os::current_stack_pointer() {
 350   typedef address get_sp_func();
 351   get_sp_func* func = CAST_TO_FN_PTR(get_sp_func*,
 352                                      StubRoutines::x86::get_previous_sp_entry());
 353   return (*func)();
 354 }
 355 #endif
 356 
 357 bool os::win32::get_frame_at_stack_banging_point(JavaThread* thread,
 358         struct _EXCEPTION_POINTERS* exceptionInfo, address pc, frame* fr) {
 359   PEXCEPTION_RECORD exceptionRecord = exceptionInfo->ExceptionRecord;
 360   address addr = (address) exceptionRecord->ExceptionInformation[1];
 361   if (Interpreter::contains(pc)) {
 362     *fr = os::fetch_frame_from_context((void*)exceptionInfo->ContextRecord);
 363     if (!fr->is_first_java_frame()) {
 364       // get_frame_at_stack_banging_point() is only called when we
 365       // have well defined stacks so java_sender() calls do not need
 366       // to assert safe_for_sender() first.
 367       *fr = fr->java_sender();
 368     }
 369   } else {
 370     // more complex code with compiled code
 371     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
 372     CodeBlob* cb = CodeCache::find_blob(pc);
 373     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
 374       // Not sure where the pc points to, fallback to default
 375       // stack overflow handling
 376       return false;
 377     } else {
 378       // in compiled code, the stack banging is performed just after the return pc
 379       // has been pushed on the stack
 380       intptr_t* fp = (intptr_t*)exceptionInfo->ContextRecord->REG_FP;
 381       intptr_t* sp = (intptr_t*)exceptionInfo->ContextRecord->REG_SP;
 382       *fr = frame(sp + 1, fp, (address)*sp);
 383       if (!fr->is_java_frame()) {
 384         // See java_sender() comment above.
 385         *fr = fr->java_sender();
 386       }
 387     }
 388   }
 389   assert(fr->is_java_frame(), "Safety check");
 390   return true;
 391 }
 392 
 393 #ifndef AMD64
 394 intptr_t* _get_previous_fp() {
 395   intptr_t **frameptr;
 396   __asm {
 397     mov frameptr, ebp
 398   };
 399   // ebp (frameptr) is for this frame (_get_previous_fp). We want the ebp for the
 400   // caller of os::current_frame*(), so go up two frames. However, for
 401   // optimized builds, _get_previous_fp() will be inlined, so only go
 402   // up 1 frame in that case.
 403 #ifdef _NMT_NOINLINE_
 404   return **(intptr_t***)frameptr;
 405 #else
 406   return *frameptr;
 407 #endif
 408 }
 409 #endif // !AMD64
 410 
 411 frame os::current_frame() {
 412 
 413 #ifdef AMD64
 414   // apparently _asm not supported on windows amd64
 415   typedef intptr_t*      get_fp_func           ();
 416   get_fp_func* func = CAST_TO_FN_PTR(get_fp_func*,
 417                                      StubRoutines::x86::get_previous_fp_entry());
 418   if (func == NULL) return frame();
 419   intptr_t* fp = (*func)();
 420   if (fp == NULL) {
 421     return frame();
 422   }
 423 #else
 424   intptr_t* fp = _get_previous_fp();
 425 #endif // AMD64
 426 
 427   frame myframe((intptr_t*)os::current_stack_pointer(),
 428                 (intptr_t*)fp,
 429                 CAST_FROM_FN_PTR(address, os::current_frame));
 430   if (os::is_first_C_frame(&myframe)) {
 431     // stack is not walkable
 432     return frame();
 433   } else {
 434     return os::get_sender_for_C_frame(&myframe);
 435   }
 436 }
 437 
 438 void os::print_context(outputStream *st, const void *context) {
 439   if (context == NULL) return;
 440 
 441   const CONTEXT* uc = (const CONTEXT*)context;
 442 
 443   st->print_cr("Registers:");
 444 #ifdef AMD64
 445   st->print(  "RAX=" INTPTR_FORMAT, uc->Rax);
 446   st->print(", RBX=" INTPTR_FORMAT, uc->Rbx);
 447   st->print(", RCX=" INTPTR_FORMAT, uc->Rcx);
 448   st->print(", RDX=" INTPTR_FORMAT, uc->Rdx);
 449   st->cr();
 450   st->print(  "RSP=" INTPTR_FORMAT, uc->Rsp);
 451   st->print(", RBP=" INTPTR_FORMAT, uc->Rbp);
 452   st->print(", RSI=" INTPTR_FORMAT, uc->Rsi);
 453   st->print(", RDI=" INTPTR_FORMAT, uc->Rdi);
 454   st->cr();
 455   st->print(  "R8 =" INTPTR_FORMAT, uc->R8);
 456   st->print(", R9 =" INTPTR_FORMAT, uc->R9);
 457   st->print(", R10=" INTPTR_FORMAT, uc->R10);
 458   st->print(", R11=" INTPTR_FORMAT, uc->R11);
 459   st->cr();
 460   st->print(  "R12=" INTPTR_FORMAT, uc->R12);
 461   st->print(", R13=" INTPTR_FORMAT, uc->R13);
 462   st->print(", R14=" INTPTR_FORMAT, uc->R14);
 463   st->print(", R15=" INTPTR_FORMAT, uc->R15);
 464   st->cr();
 465   st->print(  "RIP=" INTPTR_FORMAT, uc->Rip);
 466   st->print(", EFLAGS=" INTPTR_FORMAT, uc->EFlags);
 467 #else
 468   st->print(  "EAX=" INTPTR_FORMAT, uc->Eax);
 469   st->print(", EBX=" INTPTR_FORMAT, uc->Ebx);
 470   st->print(", ECX=" INTPTR_FORMAT, uc->Ecx);
 471   st->print(", EDX=" INTPTR_FORMAT, uc->Edx);
 472   st->cr();
 473   st->print(  "ESP=" INTPTR_FORMAT, uc->Esp);
 474   st->print(", EBP=" INTPTR_FORMAT, uc->Ebp);
 475   st->print(", ESI=" INTPTR_FORMAT, uc->Esi);
 476   st->print(", EDI=" INTPTR_FORMAT, uc->Edi);
 477   st->cr();
 478   st->print(  "EIP=" INTPTR_FORMAT, uc->Eip);
 479   st->print(", EFLAGS=" INTPTR_FORMAT, uc->EFlags);
 480 #endif // AMD64
 481   st->cr();
 482   st->cr();
 483 
 484   intptr_t *sp = (intptr_t *)uc->REG_SP;
 485   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
 486   print_hex_dump(st, (address)sp, (address)(sp + 32), sizeof(intptr_t));
 487   st->cr();
 488 
 489   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 490   // point to garbage if entry point in an nmethod is corrupted. Leave
 491   // this at the end, and hope for the best.
 492   address pc = (address)uc->REG_PC;
 493   print_instructions(st, pc, sizeof(char));
 494   st->cr();
 495 }
 496 
 497 
 498 void os::print_register_info(outputStream *st, const void *context) {
 499   if (context == NULL) return;
 500 
 501   const CONTEXT* uc = (const CONTEXT*)context;
 502 
 503   st->print_cr("Register to memory mapping:");
 504   st->cr();
 505 
 506   // this is only for the "general purpose" registers
 507 
 508 #ifdef AMD64
 509   st->print("RIP="); print_location(st, uc->Rip);
 510   st->print("RAX="); print_location(st, uc->Rax);
 511   st->print("RBX="); print_location(st, uc->Rbx);
 512   st->print("RCX="); print_location(st, uc->Rcx);
 513   st->print("RDX="); print_location(st, uc->Rdx);
 514   st->print("RSP="); print_location(st, uc->Rsp);
 515   st->print("RBP="); print_location(st, uc->Rbp);
 516   st->print("RSI="); print_location(st, uc->Rsi);
 517   st->print("RDI="); print_location(st, uc->Rdi);
 518   st->print("R8 ="); print_location(st, uc->R8);
 519   st->print("R9 ="); print_location(st, uc->R9);
 520   st->print("R10="); print_location(st, uc->R10);
 521   st->print("R11="); print_location(st, uc->R11);
 522   st->print("R12="); print_location(st, uc->R12);
 523   st->print("R13="); print_location(st, uc->R13);
 524   st->print("R14="); print_location(st, uc->R14);
 525   st->print("R15="); print_location(st, uc->R15);
 526 #else
 527   st->print("EIP="); print_location(st, uc->Eip);
 528   st->print("EAX="); print_location(st, uc->Eax);
 529   st->print("EBX="); print_location(st, uc->Ebx);
 530   st->print("ECX="); print_location(st, uc->Ecx);
 531   st->print("EDX="); print_location(st, uc->Edx);
 532   st->print("ESP="); print_location(st, uc->Esp);
 533   st->print("EBP="); print_location(st, uc->Ebp);
 534   st->print("ESI="); print_location(st, uc->Esi);
 535   st->print("EDI="); print_location(st, uc->Edi);
 536 #endif
 537 
 538   st->cr();
 539 }
 540 
 541 extern "C" int SpinPause () {
 542 #ifdef AMD64
 543    return 0 ;
 544 #else
 545    // pause == rep:nop
 546    // On systems that don't support pause a rep:nop
 547    // is executed as a nop.  The rep: prefix is ignored.
 548    _asm {
 549       pause ;
 550    };
 551    return 1 ;
 552 #endif // AMD64
 553 }
 554 
 555 juint os::cpu_microcode_revision() {
 556   juint result = 0;
 557   BYTE data[8] = {0};
 558   HKEY key;
 559   DWORD status = RegOpenKey(HKEY_LOCAL_MACHINE,
 560                "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0", &key);
 561   if (status == ERROR_SUCCESS) {
 562     DWORD size = sizeof(data);
 563     status = RegQueryValueEx(key, "Update Revision", NULL, NULL, data, &size);
 564     if (status == ERROR_SUCCESS) {
 565       if (size == 4) result = *((juint*)data);
 566       if (size == 8) result = *((juint*)data + 1); // upper 32-bits
 567     }
 568     RegCloseKey(key);
 569   }
 570   return result;
 571 }
 572 
 573 void os::setup_fpu() {
 574 #ifndef AMD64
 575   int fpu_cntrl_word = StubRoutines::fpu_cntrl_wrd_std();
 576   __asm fldcw fpu_cntrl_word;
 577 #endif // !AMD64
 578 }
 579 
 580 #ifndef PRODUCT
 581 void os::verify_stack_alignment() {
 582 #ifdef AMD64
 583   // The current_stack_pointer() calls generated get_previous_sp stub routine.
 584   // Only enable the assert after the routine becomes available.
 585   if (StubRoutines::code1() != NULL) {
 586     assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
 587   }
 588 #endif
 589 }
 590 #endif
 591 
 592 int os::extra_bang_size_in_bytes() {
 593   // JDK-8050147 requires the full cache line bang for x86.
 594   return VM_Version::L1_line_size();
 595 }