1 /*

     2  * Copyright (c) 2004, 2012, Oracle and/or its affiliates. All rights reserved.

     3  * Copyright (c) 2014, Red Hat Inc. All rights reserved.

     4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     5  *

     6  * This code is free software; you can redistribute it and/or modify it

     7  * under the terms of the GNU General Public License version 2 only, as

     8  * published by the Free Software Foundation.

     9  *

    10  * This code is distributed in the hope that it will be useful, but WITHOUT

    11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    13  * version 2 for more details (a copy is included in the LICENSE file that

    14  * accompanied this code).

    15  *

    16  * You should have received a copy of the GNU General Public License version

    17  * 2 along with this work; if not, write to the Free Software Foundation,

    18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    19  *

    20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    21  * or visit www.oracle.com if you need additional information or have any

    22  * questions.

    23  *

    24  */

    25 

    26 #include "precompiled.hpp"

    27 #include "asm/macroAssembler.hpp"

    28 #include "memory/metaspaceShared.hpp"

    29 

    30 // Generate the self-patching vtable method:

    31 //

    32 // This method will be called (as any other Klass virtual method) with

    33 // the Klass itself as the first argument.  Example:

    34 //

    35 //      oop obj;

    36 //      int size = obj->klass()->oop_size(this);

    37 //

    38 // for which the virtual method call is Klass::oop_size();

    39 //

    40 // The dummy method is called with the Klass object as the first

    41 // operand, and an object as the second argument.

    42 //

    43 

    44 //=====================================================================

    45 

    46 // All of the dummy methods in the vtable are essentially identical,

    47 // differing only by an ordinal constant, and they bear no relationship

    48 // to the original method which the caller intended. Also, there needs

    49 // to be 'vtbl_list_size' instances of the vtable in order to

    50 // differentiate between the 'vtable_list_size' original Klass objects.

    51 

    52 #define __ masm->

    53 

    54 extern "C" {

    55   void aarch64_prolog(void);

    56 }

    57 

    58 void MetaspaceShared::generate_vtable_methods(void** vtbl_list,

    59                                                    void** vtable,

    60                                                    char** md_top,

    61                                                    char* md_end,

    62                                                    char** mc_top,

    63                                                    char* mc_end) {

    64 

    65 #ifdef BUILTIN_SIM

    66   // Write a dummy word to the writable shared metaspace.

    67   // MetaspaceShared::initialize_shared_spaces will fill it with the

    68   // address of aarch64_prolog().

    69   address *prolog_ptr = (address*)*md_top;

    70   *(intptr_t *)(*md_top) = (intptr_t)0;

    71   (*md_top) += sizeof(intptr_t);

    72 #endif

    73 

    74   intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);

    75   *(intptr_t *)(*md_top) = vtable_bytes;

    76   *md_top += sizeof(intptr_t);

    77   void** dummy_vtable = (void**)*md_top;

    78   *vtable = dummy_vtable;

    79   *md_top += vtable_bytes;

    80 

    81   // Get ready to generate dummy methods.

    82 

    83   CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);

    84   MacroAssembler* masm = new MacroAssembler(&cb);

    85 

    86   Label common_code;

    87   for (int i = 0; i < vtbl_list_size; ++i) {

    88     for (int j = 0; j < num_virtuals; ++j) {

    89       dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();

    90 

    91       // We're called directly from C code.

    92 #ifdef BUILTIN_SIM

    93       __ c_stub_prolog(8, 0, MacroAssembler::ret_type_integral, prolog_ptr);

    94 #endif

    95       // Load rscratch1 with a value indicating vtable/offset pair.

    96       // -- bits[ 7..0]  (8 bits) which virtual method in table?

    97       // -- bits[12..8]  (5 bits) which virtual method table?

    98       __ mov(rscratch1, (i << 8) + j);

    99       __ b(common_code);

   100     }

   101   }

   102 

   103   __ bind(common_code);

   104 

   105   Register tmp0 = r10, tmp1 = r11;       // AAPCS64 temporary registers

   106   __ enter();

   107   __ lsr(tmp0, rscratch1, 8);            // isolate vtable identifier.

   108   __ mov(tmp1, (address)vtbl_list);      // address of list of vtable pointers.

   109   __ ldr(tmp1, Address(tmp1, tmp0, Address::lsl(LogBytesPerWord))); // get correct vtable pointer.

   110   __ str(tmp1, Address(c_rarg0));        // update vtable pointer in obj.

   111   __ add(rscratch1, tmp1, rscratch1, ext::uxtb, LogBytesPerWord); // address of real method pointer.

   112   __ ldr(rscratch1, Address(rscratch1)); // get real method pointer.

   113   __ blrt(rscratch1, 8, 0, 1);           // jump to the real method.

   114   __ leave();

   115   __ ret(lr);

   116 

   117   *mc_top = (char*)__ pc();

   118 }

   119 

   120 #ifdef BUILTIN_SIM

   121 void MetaspaceShared::relocate_vtbl_list(char **buffer) {

   122   void **sim_entry = (void**)*buffer;

   123   *sim_entry = (void*)aarch64_prolog;

   124   *buffer += sizeof(intptr_t);

   125 }

   126 #endif