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