1 | /* |
2 | * Copyright (C) 2009 Apple Inc. All rights reserved. |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions |
6 | * are met: |
7 | * 1. Redistributions of source code must retain the above copyright |
8 | * notice, this list of conditions and the following disclaimer. |
9 | * 2. Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
14 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
17 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
18 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
20 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
21 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
23 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
24 | */ |
25 | |
26 | #ifndef LinkBuffer_h |
27 | #define LinkBuffer_h |
28 | |
29 | #include <wtf/Platform.h> |
30 | |
31 | #if ENABLE(ASSEMBLER) |
32 | |
33 | #include <MacroAssembler.h> |
34 | #include <wtf/Noncopyable.h> |
35 | |
36 | namespace JSC { |
37 | |
38 | // LinkBuffer: |
39 | // |
40 | // This class assists in linking code generated by the macro assembler, once code generation |
41 | // has been completed, and the code has been copied to is final location in memory. At this |
42 | // time pointers to labels within the code may be resolved, and relative offsets to external |
43 | // addresses may be fixed. |
44 | // |
45 | // Specifically: |
46 | // * Jump objects may be linked to external targets, |
47 | // * The address of Jump objects may taken, such that it can later be relinked. |
48 | // * The return address of a Call may be acquired. |
49 | // * The address of a Label pointing into the code may be resolved. |
50 | // * The value referenced by a DataLabel may be set. |
51 | // |
52 | class LinkBuffer : public Noncopyable { |
53 | typedef MacroAssemblerCodeRef CodeRef; |
54 | typedef MacroAssembler::Label Label; |
55 | typedef MacroAssembler::Jump Jump; |
56 | typedef MacroAssembler::JumpList JumpList; |
57 | typedef MacroAssembler::Call Call; |
58 | typedef MacroAssembler::DataLabel32 DataLabel32; |
59 | typedef MacroAssembler::DataLabelPtr DataLabelPtr; |
60 | |
61 | public: |
62 | // Note: Initialization sequence is significant, since executablePool is a PassRefPtr. |
63 | // First, executablePool is copied into m_executablePool, then the initialization of |
64 | // m_code uses m_executablePool, *not* executablePool, since this is no longer valid. |
65 | LinkBuffer(MacroAssembler* masm, PassRefPtr<ExecutablePool> executablePool) |
66 | : m_executablePool(executablePool) |
67 | , m_code(masm->m_assembler.executableCopy(allocator: m_executablePool.get())) |
68 | , m_size(masm->m_assembler.size()) |
69 | #ifndef NDEBUG |
70 | , m_completed(false) |
71 | #endif |
72 | { |
73 | } |
74 | |
75 | ~LinkBuffer() |
76 | { |
77 | ASSERT(m_completed); |
78 | } |
79 | |
80 | // These methods are used to link or set values at code generation time. |
81 | |
82 | void link(Call call, FunctionPtr function) |
83 | { |
84 | ASSERT(call.isFlagSet(Call::Linkable)); |
85 | MacroAssembler::linkCall(code: code(), call, function); |
86 | } |
87 | |
88 | void link(Jump jump, CodeLocationLabel label) |
89 | { |
90 | MacroAssembler::linkJump(code: code(), jump, target: label); |
91 | } |
92 | |
93 | void link(JumpList list, CodeLocationLabel label) |
94 | { |
95 | for (unsigned i = 0; i < list.m_jumps.size(); ++i) |
96 | MacroAssembler::linkJump(code: code(), jump: list.m_jumps[i], target: label); |
97 | } |
98 | |
99 | void patch(DataLabelPtr label, void* value) |
100 | { |
101 | MacroAssembler::linkPointer(code: code(), label: label.m_label, value); |
102 | } |
103 | |
104 | void patch(DataLabelPtr label, CodeLocationLabel value) |
105 | { |
106 | MacroAssembler::linkPointer(code: code(), label: label.m_label, value: value.executableAddress()); |
107 | } |
108 | |
109 | // These methods are used to obtain handles to allow the code to be relinked / repatched later. |
110 | |
111 | CodeLocationCall locationOf(Call call) |
112 | { |
113 | ASSERT(call.isFlagSet(Call::Linkable)); |
114 | ASSERT(!call.isFlagSet(Call::Near)); |
115 | return CodeLocationCall(MacroAssembler::getLinkerAddress(code: code(), label: call.m_jmp)); |
116 | } |
117 | |
118 | CodeLocationNearCall locationOfNearCall(Call call) |
119 | { |
120 | ASSERT(call.isFlagSet(Call::Linkable)); |
121 | ASSERT(call.isFlagSet(Call::Near)); |
122 | return CodeLocationNearCall(MacroAssembler::getLinkerAddress(code: code(), label: call.m_jmp)); |
123 | } |
124 | |
125 | CodeLocationLabel locationOf(Label label) |
126 | { |
127 | return CodeLocationLabel(MacroAssembler::getLinkerAddress(code: code(), label: label.m_label)); |
128 | } |
129 | |
130 | CodeLocationDataLabelPtr locationOf(DataLabelPtr label) |
131 | { |
132 | return CodeLocationDataLabelPtr(MacroAssembler::getLinkerAddress(code: code(), label: label.m_label)); |
133 | } |
134 | |
135 | CodeLocationDataLabel32 locationOf(DataLabel32 label) |
136 | { |
137 | return CodeLocationDataLabel32(MacroAssembler::getLinkerAddress(code: code(), label: label.m_label)); |
138 | } |
139 | |
140 | // This method obtains the return address of the call, given as an offset from |
141 | // the start of the code. |
142 | unsigned returnAddressOffset(Call call) |
143 | { |
144 | return MacroAssembler::getLinkerCallReturnOffset(call); |
145 | } |
146 | |
147 | // Upon completion of all patching either 'finalizeCode()' or 'finalizeCodeAddendum()' should be called |
148 | // once to complete generation of the code. 'finalizeCode()' is suited to situations |
149 | // where the executable pool must also be retained, the lighter-weight 'finalizeCodeAddendum()' is |
150 | // suited to adding to an existing allocation. |
151 | CodeRef finalizeCode() |
152 | { |
153 | performFinalization(); |
154 | |
155 | return CodeRef(m_code, m_executablePool, m_size); |
156 | } |
157 | CodeLocationLabel finalizeCodeAddendum() |
158 | { |
159 | performFinalization(); |
160 | |
161 | return CodeLocationLabel(code()); |
162 | } |
163 | |
164 | private: |
165 | // Keep this private! - the underlying code should only be obtained externally via |
166 | // finalizeCode() or finalizeCodeAddendum(). |
167 | void* code() |
168 | { |
169 | return m_code; |
170 | } |
171 | |
172 | void performFinalization() |
173 | { |
174 | #ifndef NDEBUG |
175 | ASSERT(!m_completed); |
176 | m_completed = true; |
177 | #endif |
178 | |
179 | ExecutableAllocator::makeExecutable(code(), m_size); |
180 | ExecutableAllocator::cacheFlush(code(), m_size); |
181 | } |
182 | |
183 | RefPtr<ExecutablePool> m_executablePool; |
184 | void* m_code; |
185 | size_t m_size; |
186 | #ifndef NDEBUG |
187 | bool m_completed; |
188 | #endif |
189 | }; |
190 | |
191 | } // namespace JSC |
192 | |
193 | #endif // ENABLE(ASSEMBLER) |
194 | |
195 | #endif // LinkBuffer_h |
196 | |