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1 // Copyright (c) 2010, Google Inc. | |
2 // 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 are | |
6 // met: | |
7 // | |
8 // * Redistributions of source code must retain the above copyright | |
9 // notice, this list of conditions and the following disclaimer. | |
10 // * Redistributions in binary form must reproduce the above | |
11 // copyright notice, this list of conditions and the following disclaimer | |
12 // in the documentation and/or other materials provided with the | |
13 // distribution. | |
14 // * Neither the name of Google Inc. nor the names of its | |
15 // contributors may be used to endorse or promote products derived from | |
16 // this software without specific prior written permission. | |
17 // | |
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
29 | |
30 // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com> | |
31 | |
32 // cfi_assembler.cc: Implementation of google_breakpad::CFISection class. | |
33 // See cfi_assembler.h for details. | |
34 | |
35 #include <cassert> | |
36 #include <stdlib.h> | |
37 | |
38 #include "common/dwarf/cfi_assembler.h" | |
39 | |
40 namespace google_breakpad { | |
41 | |
42 using dwarf2reader::DwarfPointerEncoding; | |
43 | |
44 CFISection &CFISection::CIEHeader(u_int64_t code_alignment_factor, | |
45 int data_alignment_factor, | |
46 unsigned return_address_register, | |
47 u_int8_t version, | |
48 const string &augmentation, | |
49 bool dwarf64) { | |
50 assert(!entry_length_); | |
51 entry_length_ = new PendingLength(); | |
52 in_fde_ = false; | |
53 | |
54 if (dwarf64) { | |
55 D32(0xffffffff); | |
56 D64(entry_length_->length); | |
57 entry_length_->start = Here(); | |
58 // Write the CIE distinguished value. In .debug_frame sections, it's | |
59 // ~0; in .eh_frame sections, it's zero. | |
60 D64(eh_frame_ ? 0 : ~(u_int64_t)0); | |
61 } else { | |
62 D32(entry_length_->length); | |
63 entry_length_->start = Here(); | |
64 // Write the CIE distinguished value. In .debug_frame sections, it's | |
65 // ~0; in .eh_frame sections, it's zero. | |
66 D32(eh_frame_ ? 0 : ~(u_int32_t)0); | |
67 } | |
68 D8(version); | |
69 AppendCString(augmentation); | |
70 ULEB128(code_alignment_factor); | |
71 LEB128(data_alignment_factor); | |
72 if (version == 1) | |
73 D8(return_address_register); | |
74 else | |
75 ULEB128(return_address_register); | |
76 return *this; | |
77 } | |
78 | |
79 CFISection &CFISection::FDEHeader(Label cie_pointer, | |
80 u_int64_t initial_location, | |
81 u_int64_t address_range, | |
82 bool dwarf64) { | |
83 assert(!entry_length_); | |
84 entry_length_ = new PendingLength(); | |
85 in_fde_ = true; | |
86 fde_start_address_ = initial_location; | |
87 | |
88 if (dwarf64) { | |
89 D32(0xffffffff); | |
90 D64(entry_length_->length); | |
91 entry_length_->start = Here(); | |
92 if (eh_frame_) | |
93 D64(Here() - cie_pointer); | |
94 else | |
95 D64(cie_pointer); | |
96 } else { | |
97 D32(entry_length_->length); | |
98 entry_length_->start = Here(); | |
99 if (eh_frame_) | |
100 D32(Here() - cie_pointer); | |
101 else | |
102 D32(cie_pointer); | |
103 } | |
104 EncodedPointer(initial_location); | |
105 // The FDE length in an .eh_frame section uses the same encoding as the | |
106 // initial location, but ignores the base address (selected by the upper | |
107 // nybble of the encoding), as it's a length, not an address that can be | |
108 // made relative. | |
109 EncodedPointer(address_range, | |
110 DwarfPointerEncoding(pointer_encoding_ & 0x0f)); | |
111 return *this; | |
112 } | |
113 | |
114 CFISection &CFISection::FinishEntry() { | |
115 assert(entry_length_); | |
116 Align(address_size_, dwarf2reader::DW_CFA_nop); | |
117 entry_length_->length = Here() - entry_length_->start; | |
118 delete entry_length_; | |
119 entry_length_ = NULL; | |
120 in_fde_ = false; | |
121 return *this; | |
122 } | |
123 | |
124 CFISection &CFISection::EncodedPointer(u_int64_t address, | |
125 DwarfPointerEncoding encoding, | |
126 const EncodedPointerBases &bases) { | |
127 // Omitted data is extremely easy to emit. | |
128 if (encoding == dwarf2reader::DW_EH_PE_omit) | |
129 return *this; | |
130 | |
131 // If (encoding & dwarf2reader::DW_EH_PE_indirect) != 0, then we assume | |
132 // that ADDRESS is the address at which the pointer is stored --- in | |
133 // other words, that bit has no effect on how we write the pointer. | |
134 encoding = DwarfPointerEncoding(encoding & ~dwarf2reader::DW_EH_PE_indirect); | |
135 | |
136 // Find the base address to which this pointer is relative. The upper | |
137 // nybble of the encoding specifies this. | |
138 u_int64_t base; | |
139 switch (encoding & 0xf0) { | |
140 case dwarf2reader::DW_EH_PE_absptr: base = 0; break; | |
141 case dwarf2reader::DW_EH_PE_pcrel: base = bases.cfi + Size(); break; | |
142 case dwarf2reader::DW_EH_PE_textrel: base = bases.text; break; | |
143 case dwarf2reader::DW_EH_PE_datarel: base = bases.data; break; | |
144 case dwarf2reader::DW_EH_PE_funcrel: base = fde_start_address_; break; | |
145 case dwarf2reader::DW_EH_PE_aligned: base = 0; break; | |
146 default: abort(); | |
147 }; | |
148 | |
149 // Make ADDRESS relative. Yes, this is appropriate even for "absptr" | |
150 // values; see gcc/unwind-pe.h. | |
151 address -= base; | |
152 | |
153 // Align the pointer, if required. | |
154 if ((encoding & 0xf0) == dwarf2reader::DW_EH_PE_aligned) | |
155 Align(AddressSize()); | |
156 | |
157 // Append ADDRESS to this section in the appropriate form. For the | |
158 // fixed-width forms, we don't need to differentiate between signed and | |
159 // unsigned encodings, because ADDRESS has already been extended to 64 | |
160 // bits before it was passed to us. | |
161 switch (encoding & 0x0f) { | |
162 case dwarf2reader::DW_EH_PE_absptr: | |
163 Address(address); | |
164 break; | |
165 | |
166 case dwarf2reader::DW_EH_PE_uleb128: | |
167 ULEB128(address); | |
168 break; | |
169 | |
170 case dwarf2reader::DW_EH_PE_sleb128: | |
171 LEB128(address); | |
172 break; | |
173 | |
174 case dwarf2reader::DW_EH_PE_udata2: | |
175 case dwarf2reader::DW_EH_PE_sdata2: | |
176 D16(address); | |
177 break; | |
178 | |
179 case dwarf2reader::DW_EH_PE_udata4: | |
180 case dwarf2reader::DW_EH_PE_sdata4: | |
181 D32(address); | |
182 break; | |
183 | |
184 case dwarf2reader::DW_EH_PE_udata8: | |
185 case dwarf2reader::DW_EH_PE_sdata8: | |
186 D64(address); | |
187 break; | |
188 | |
189 default: | |
190 abort(); | |
191 } | |
192 | |
193 return *this; | |
194 }; | |
195 | |
196 } // namespace google_breakpad | |
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