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b4c522fa | 1 | // Exception handling and frame unwind runtime interface routines. |
8d9254fc | 2 | // Copyright (C) 2011-2020 Free Software Foundation, Inc. |
b4c522fa IB |
3 | |
4 | // GCC is free software; you can redistribute it and/or modify it under | |
5 | // the terms of the GNU General Public License as published by the Free | |
6 | // Software Foundation; either version 3, or (at your option) any later | |
7 | // version. | |
8 | ||
9 | // GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
10 | // WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 | // for more details. | |
13 | ||
14 | // Under Section 7 of GPL version 3, you are granted additional | |
15 | // permissions described in the GCC Runtime Library Exception, version | |
16 | // 3.1, as published by the Free Software Foundation. | |
17 | ||
18 | // You should have received a copy of the GNU General Public License and | |
19 | // a copy of the GCC Runtime Library Exception along with this program; | |
20 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
21 | // <http://www.gnu.org/licenses/>. | |
22 | ||
23 | // extern(C) interface for the GNU/GCC pointer encoding library. | |
24 | // This corresponds to unwind-pe.h | |
25 | ||
26 | module gcc.unwind.pe; | |
27 | ||
28 | import gcc.unwind; | |
29 | import gcc.builtins; | |
30 | ||
31 | @nogc: | |
32 | ||
33 | // Pointer encodings, from dwarf2.h. | |
34 | enum | |
35 | { | |
36 | DW_EH_PE_absptr = 0x00, | |
37 | DW_EH_PE_omit = 0xff, | |
38 | ||
39 | DW_EH_PE_uleb128 = 0x01, | |
40 | DW_EH_PE_udata2 = 0x02, | |
41 | DW_EH_PE_udata4 = 0x03, | |
42 | DW_EH_PE_udata8 = 0x04, | |
43 | DW_EH_PE_sleb128 = 0x09, | |
44 | DW_EH_PE_sdata2 = 0x0A, | |
45 | DW_EH_PE_sdata4 = 0x0B, | |
46 | DW_EH_PE_sdata8 = 0x0C, | |
47 | DW_EH_PE_signed = 0x08, | |
48 | ||
49 | DW_EH_PE_pcrel = 0x10, | |
50 | DW_EH_PE_textrel = 0x20, | |
51 | DW_EH_PE_datarel = 0x30, | |
52 | DW_EH_PE_funcrel = 0x40, | |
53 | DW_EH_PE_aligned = 0x50, | |
54 | ||
55 | DW_EH_PE_indirect = 0x80 | |
56 | } | |
57 | ||
58 | // Given an encoding, return the number of bytes the format occupies. | |
59 | // This is only defined for fixed-size encodings, and so does not | |
60 | // include leb128. | |
61 | uint size_of_encoded_value(ubyte encoding) | |
62 | { | |
63 | if (encoding == DW_EH_PE_omit) | |
64 | return 0; | |
65 | ||
66 | final switch (encoding & 0x07) | |
67 | { | |
68 | case DW_EH_PE_absptr: | |
69 | return (void*).sizeof; | |
70 | case DW_EH_PE_udata2: | |
71 | return 2; | |
72 | case DW_EH_PE_udata4: | |
73 | return 4; | |
74 | case DW_EH_PE_udata8: | |
75 | return 8; | |
76 | } | |
77 | assert(0); | |
78 | } | |
79 | ||
80 | // Given an encoding and an _Unwind_Context, return the base to which | |
81 | // the encoding is relative. This base may then be passed to | |
82 | // read_encoded_value_with_base for use when the _Unwind_Context is | |
83 | // not available. | |
84 | _Unwind_Ptr base_of_encoded_value(ubyte encoding, _Unwind_Context* context) | |
85 | { | |
86 | if (encoding == DW_EH_PE_omit) | |
87 | return cast(_Unwind_Ptr) 0; | |
88 | ||
89 | final switch (encoding & 0x70) | |
90 | { | |
91 | case DW_EH_PE_absptr: | |
92 | case DW_EH_PE_pcrel: | |
93 | case DW_EH_PE_aligned: | |
94 | return cast(_Unwind_Ptr) 0; | |
95 | ||
96 | case DW_EH_PE_textrel: | |
97 | return _Unwind_GetTextRelBase(context); | |
98 | case DW_EH_PE_datarel: | |
99 | return _Unwind_GetDataRelBase(context); | |
100 | case DW_EH_PE_funcrel: | |
101 | return _Unwind_GetRegionStart(context); | |
102 | } | |
103 | assert(0); | |
104 | } | |
105 | ||
106 | // Read an unsigned leb128 value from P, *P is incremented past the value. | |
107 | // We assume that a word is large enough to hold any value so encoded; | |
108 | // if it is smaller than a pointer on some target, pointers should not be | |
109 | // leb128 encoded on that target. | |
110 | _uleb128_t read_uleb128(const(ubyte)** p) | |
111 | { | |
112 | auto q = *p; | |
113 | _uleb128_t result = 0; | |
114 | uint shift = 0; | |
115 | ||
116 | while (1) | |
117 | { | |
118 | ubyte b = *q++; | |
119 | result |= cast(_uleb128_t)(b & 0x7F) << shift; | |
120 | if ((b & 0x80) == 0) | |
121 | break; | |
122 | shift += 7; | |
123 | } | |
124 | ||
125 | *p = q; | |
126 | return result; | |
127 | } | |
128 | ||
129 | // Similar, but read a signed leb128 value. | |
130 | _sleb128_t read_sleb128(const(ubyte)** p) | |
131 | { | |
132 | auto q = *p; | |
133 | _sleb128_t result = 0; | |
134 | uint shift = 0; | |
135 | ubyte b = void; | |
136 | ||
137 | while (1) | |
138 | { | |
139 | b = *q++; | |
140 | result |= cast(_sleb128_t)(b & 0x7F) << shift; | |
141 | shift += 7; | |
142 | if ((b & 0x80) == 0) | |
143 | break; | |
144 | } | |
145 | ||
146 | // Sign-extend a negative value. | |
147 | if (shift < result.sizeof * 8 && (b & 0x40)) | |
148 | result |= -(cast(_sleb128_t)1 << shift); | |
149 | ||
150 | *p = q; | |
151 | return result; | |
152 | } | |
153 | ||
154 | // Load an encoded value from memory at P. The value is returned in VAL; | |
155 | // The function returns P incremented past the value. BASE is as given | |
156 | // by base_of_encoded_value for this encoding in the appropriate context. | |
157 | _Unwind_Ptr read_encoded_value_with_base(ubyte encoding, _Unwind_Ptr base, | |
158 | const(ubyte)** p) | |
159 | { | |
160 | auto q = *p; | |
161 | _Unwind_Internal_Ptr result; | |
162 | ||
163 | if (encoding == DW_EH_PE_aligned) | |
164 | { | |
165 | _Unwind_Internal_Ptr a = cast(_Unwind_Internal_Ptr)q; | |
166 | a = cast(_Unwind_Internal_Ptr)((a + (void*).sizeof - 1) & - (void*).sizeof); | |
167 | result = *cast(_Unwind_Internal_Ptr*)a; | |
168 | q = cast(ubyte*) cast(_Unwind_Internal_Ptr)(a + (void*).sizeof); | |
169 | } | |
170 | else | |
171 | { | |
172 | switch (encoding & 0x0f) | |
173 | { | |
174 | case DW_EH_PE_uleb128: | |
175 | result = cast(_Unwind_Internal_Ptr)read_uleb128(&q); | |
176 | break; | |
177 | ||
178 | case DW_EH_PE_sleb128: | |
179 | result = cast(_Unwind_Internal_Ptr)read_sleb128(&q); | |
180 | break; | |
181 | ||
182 | case DW_EH_PE_udata2: | |
183 | result = cast(_Unwind_Internal_Ptr) *cast(ushort*)q; | |
184 | q += 2; | |
185 | break; | |
186 | case DW_EH_PE_udata4: | |
187 | result = cast(_Unwind_Internal_Ptr) *cast(uint*)q; | |
188 | q += 4; | |
189 | break; | |
190 | case DW_EH_PE_udata8: | |
191 | result = cast(_Unwind_Internal_Ptr) *cast(ulong*)q; | |
192 | q += 8; | |
193 | break; | |
194 | ||
195 | case DW_EH_PE_sdata2: | |
196 | result = cast(_Unwind_Internal_Ptr) *cast(short*)q; | |
197 | q += 2; | |
198 | break; | |
199 | case DW_EH_PE_sdata4: | |
200 | result = cast(_Unwind_Internal_Ptr) *cast(int*)q; | |
201 | q += 4; | |
202 | break; | |
203 | case DW_EH_PE_sdata8: | |
204 | result = cast(_Unwind_Internal_Ptr) *cast(long*)q; | |
205 | q += 8; | |
206 | break; | |
207 | ||
208 | case DW_EH_PE_absptr: | |
209 | if (size_t.sizeof == 8) | |
210 | goto case DW_EH_PE_udata8; | |
211 | else | |
212 | goto case DW_EH_PE_udata4; | |
213 | ||
214 | default: | |
215 | __builtin_abort(); | |
216 | } | |
217 | ||
218 | if (result != 0) | |
219 | { | |
220 | result += ((encoding & 0x70) == DW_EH_PE_pcrel | |
221 | ? cast(_Unwind_Internal_Ptr)*p : base); | |
222 | if (encoding & DW_EH_PE_indirect) | |
223 | result = *cast(_Unwind_Internal_Ptr*)result; | |
224 | } | |
225 | } | |
226 | ||
227 | *p = q; | |
228 | return result; | |
229 | } | |
230 | ||
231 | // Like read_encoded_value_with_base, but get the base from the context | |
232 | // rather than providing it directly. | |
233 | _Unwind_Ptr read_encoded_value(_Unwind_Context* context, ubyte encoding, | |
234 | const(ubyte)** p) | |
235 | { | |
236 | auto base = base_of_encoded_value(encoding, context); | |
237 | return read_encoded_value_with_base(encoding, base, p); | |
238 | } |