1 /*

     2  * Copyright (c) 2008, 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 "assembler_arm.inline.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 void MetaspaceShared::generate_vtable_methods(void** vtbl_list,

    55                                                    void** vtable,

    56                                                    char** md_top,

    57                                                    char* md_end,

    58                                                    char** mc_top,

    59                                                    char* mc_end) {

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

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

    62   *md_top += sizeof(intptr_t);

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

    64   *vtable = dummy_vtable;

    65   *md_top += vtable_bytes;

    66 

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

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

    69 

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

    71     Label common_code;

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

    73       dummy_vtable[num_virtuals * i + j] = (void*) __ pc();

    74       __ mov(Rtemp, j);  // Rtemp contains an index of a virtual method in the table

    75       __ b(common_code);

    76     }

    77 

    78     InlinedAddress vtable_address((address)&vtbl_list[i]);

    79     __ bind(common_code);

    80     const Register tmp2 = AARCH64_ONLY(Rtemp2) NOT_AARCH64(R4);

    81     assert_different_registers(Rtemp, tmp2);

    82 #ifndef AARCH64

    83     __ push(tmp2);

    84 #endif // !AARCH64

    85     // Do not use ldr_global since the code must be portable across all ARM architectures

    86     __ ldr_literal(tmp2, vtable_address);

    87     __ ldr(tmp2, Address(tmp2));                              // get correct vtable address

    88     __ ldr(Rtemp, Address::indexed_ptr(tmp2, Rtemp));         // get real method pointer

    89     __ str(tmp2, Address(R0));                                // update vtable. R0 = "this"

    90 #ifndef AARCH64

    91     __ pop(tmp2);

    92 #endif // !AARCH64

    93     __ jump(Rtemp);

    94     __ bind_literal(vtable_address);

    95   }

    96 

    97   __ flush();

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

    99 }