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111
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1 /* Subroutines needed for unwinding stack frames for exception handling. */
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145
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2 /* Copyright (C) 1997-2020 Free Software Foundation, Inc.
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111
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3 Contributed by Jason Merrill <jason@cygnus.com>.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify it under
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8 the terms of the GNU General Public License as published by the Free
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9 Software Foundation; either version 3, or (at your option) any later
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10 version.
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11
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12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 Under Section 7 of GPL version 3, you are granted additional
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18 permissions described in the GCC Runtime Library Exception, version
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19 3.1, as published by the Free Software Foundation.
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20
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21 You should have received a copy of the GNU General Public License and
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22 a copy of the GCC Runtime Library Exception along with this program;
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23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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24 <http://www.gnu.org/licenses/>. */
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25
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26 #ifndef GCC_UNWIND_DW2_FDE_H
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27 #define GCC_UNWIND_DW2_FDE_H
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28
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29 #ifndef HIDE_EXPORTS
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30 #pragma GCC visibility push(default)
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31 #endif
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32
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33 struct fde_vector
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34 {
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35 const void *orig_data;
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36 size_t count;
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37 const struct dwarf_fde *array[];
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38 };
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39
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40 struct object
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41 {
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42 void *pc_begin;
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43 void *tbase;
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44 void *dbase;
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45 union {
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46 const struct dwarf_fde *single;
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47 struct dwarf_fde **array;
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48 struct fde_vector *sort;
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49 } u;
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50
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51 union {
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52 struct {
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53 unsigned long sorted : 1;
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54 unsigned long from_array : 1;
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55 unsigned long mixed_encoding : 1;
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56 unsigned long encoding : 8;
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57 /* ??? Wish there was an easy way to detect a 64-bit host here;
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58 we've got 32 bits left to play with... */
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59 unsigned long count : 21;
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60 } b;
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61 size_t i;
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62 } s;
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63
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64 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
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65 char *fde_end;
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66 #endif
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67
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68 struct object *next;
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69 };
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70
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71 /* This is the original definition of struct object. While the struct
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72 itself was opaque to users, they did know how large it was, and
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73 allocate one statically in crtbegin for each DSO. Keep this around
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74 so that we're aware of the static size limitations for the new struct. */
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75 struct old_object
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76 {
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77 void *pc_begin;
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78 void *pc_end;
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79 struct dwarf_fde *fde_begin;
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80 struct dwarf_fde **fde_array;
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81 size_t count;
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82 struct old_object *next;
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83 };
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84
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85 struct dwarf_eh_bases
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86 {
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87 void *tbase;
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88 void *dbase;
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89 void *func;
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90 };
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91
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92
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93 extern void __register_frame_info_bases (const void *, struct object *,
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94 void *, void *);
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95 extern void __register_frame_info (const void *, struct object *);
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96 extern void __register_frame (void *);
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97 extern void __register_frame_info_table_bases (void *, struct object *,
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98 void *, void *);
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99 extern void __register_frame_info_table (void *, struct object *);
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100 extern void __register_frame_table (void *);
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101 extern void *__deregister_frame_info (const void *);
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102 extern void *__deregister_frame_info_bases (const void *);
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103 extern void __deregister_frame (void *);
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104
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105
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106 typedef int sword __attribute__ ((mode (SI)));
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107 typedef unsigned int uword __attribute__ ((mode (SI)));
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108 typedef unsigned int uaddr __attribute__ ((mode (pointer)));
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109 typedef int saddr __attribute__ ((mode (pointer)));
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110 typedef unsigned char ubyte;
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111
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112 /* Terminology:
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113 CIE - Common Information Element
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114 FDE - Frame Descriptor Element
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115
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116 There is one per function, and it describes where the function code
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117 is located, and what the register lifetimes and stack layout are
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118 within the function.
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119
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120 The data structures are defined in the DWARF specification, although
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121 not in a very readable way (see LITERATURE).
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122
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123 Every time an exception is thrown, the code needs to locate the FDE
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124 for the current function, and starts to look for exception regions
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125 from that FDE. This works in a two-level search:
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126 a) in a linear search, find the shared image (i.e. DLL) containing
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127 the PC
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128 b) using the FDE table for that shared object, locate the FDE using
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129 binary search (which requires the sorting). */
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130
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131 /* The first few fields of a CIE. The CIE_id field is 0 for a CIE,
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132 to distinguish it from a valid FDE. FDEs are aligned to an addressing
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133 unit boundary, but the fields within are unaligned. */
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134 struct dwarf_cie
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135 {
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136 uword length;
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137 sword CIE_id;
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138 ubyte version;
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139 unsigned char augmentation[];
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140 } __attribute__ ((packed, aligned (__alignof__ (void *))));
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141
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142 /* The first few fields of an FDE. */
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143 struct dwarf_fde
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144 {
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145 uword length;
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146 sword CIE_delta;
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147 unsigned char pc_begin[];
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148 } __attribute__ ((packed, aligned (__alignof__ (void *))));
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149
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150 typedef struct dwarf_fde fde;
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151
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152 /* Locate the CIE for a given FDE. */
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153
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154 static inline const struct dwarf_cie *
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155 get_cie (const struct dwarf_fde *f)
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156 {
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157 return (const void *)&f->CIE_delta - f->CIE_delta;
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158 }
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159
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160 static inline const fde *
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161 next_fde (const fde *f)
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162 {
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163 return (const fde *) ((const char *) f + f->length + sizeof (f->length));
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164 }
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165
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166 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
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167
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168 static inline int
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169 last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
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170 {
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171 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
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172 return f == (const fde *) obj->fde_end || f->length == 0;
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173 #else
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174 return f->length == 0;
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175 #endif
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176 }
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177
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178 #ifndef HIDE_EXPORTS
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179 #pragma GCC visibility pop
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180 #endif
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181
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182 #endif /* unwind-dw2-fde.h */
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