1 /*
   2  * Copyright (c) 1999, 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 #include "precompiled.hpp"
  26 #include "asm/macroAssembler.hpp"
  27 #include "asm/macroAssembler.inline.hpp"
  28 #include "runtime/os.hpp"
  29 
  30 void MacroAssembler::int3() {
  31   emit_int8((unsigned char)0xCC);
  32 }
  33 
  34 #ifndef _LP64
  35 //  The current scheme to accelerate access to the thread
  36 //  pointer is to store the current thread in the os_exception_wrapper
  37 //  and reference the current thread from stubs and compiled code
  38 //  via the FS register.  FS[0] contains a pointer to the structured
  39 //  exception block which is actually a stack address.  The first time
  40 //  we call the os exception wrapper, we calculate and store the
  41 //  offset from this exception block and use that offset here.
  42 //
  43 //  The last mechanism we used was problematic in that the
  44 //  the offset we had hard coded in the VM kept changing as Microsoft
  45 //  evolved the OS.
  46 //
  47 // Warning: This mechanism assumes that we only attempt to get the
  48 //          thread when we are nested below a call wrapper.
  49 //
  50 // movl reg, fs:[0]                        Get exeception pointer
  51 // movl reg, [reg + thread_ptr_offset]     Load thread
  52 //
  53 void MacroAssembler::get_thread(Register thread) {
  54   // can't use ExternalAddress because it can't take NULL
  55   AddressLiteral null(0, relocInfo::none);
  56 
  57   prefix(FS_segment);
  58   movptr(thread, null);
  59   assert(os::win32::get_thread_ptr_offset() != 0,
  60          "Thread Pointer Offset has not been initialized");
  61   movl(thread, Address(thread, os::win32::get_thread_ptr_offset()));
  62 }
  63 
  64 // #else - use shared x86 implementation in cpu/x86/vm/macroAssembler_x86.cpp
  65 
  66 #endif