0
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1 /* Fallback frame-state unwinder for Darwin.
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2 Copyright (C) 2004, 2005, 2007, 2009 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3, or (at your option)
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9 any later version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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14 License for more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 #ifdef __ppc__
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26
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27 #include "tconfig.h"
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28 #include "tsystem.h"
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29 #include "coretypes.h"
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30 #include "tm.h"
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31 #include "dwarf2.h"
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32 #include "unwind.h"
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33 #include "unwind-dw2.h"
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34 #include <stdint.h>
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35 #include <stdbool.h>
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36 #include <sys/types.h>
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37 #include <signal.h>
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38
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39 #define R_LR 65
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40 #define R_CTR 66
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41 #define R_CR2 70
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42 #define R_XER 76
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43 #define R_VR0 77
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44 #define R_VRSAVE 109
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45 #define R_VSCR 110
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46 #define R_SPEFSCR 112
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47
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48 typedef unsigned long reg_unit;
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49
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50 /* Place in GPRS the parameters to the first 'sc' instruction that would
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51 have been executed if we were returning from this CONTEXT, or
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52 return false if an unexpected instruction is encountered. */
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53
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54 static bool
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55 interpret_libc (reg_unit gprs[32], struct _Unwind_Context *context)
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56 {
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57 uint32_t *pc = (uint32_t *)_Unwind_GetIP (context);
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58 uint32_t cr;
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59 reg_unit lr = (reg_unit) pc;
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60 reg_unit ctr = 0;
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61 uint32_t *invalid_address = NULL;
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62
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63 int i;
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64
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65 for (i = 0; i < 13; i++)
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66 gprs[i] = 1;
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67 gprs[1] = _Unwind_GetCFA (context);
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68 for (; i < 32; i++)
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69 gprs[i] = _Unwind_GetGR (context, i);
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70 cr = _Unwind_GetGR (context, R_CR2);
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71
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72 /* For each supported Libc, we have to track the code flow
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73 all the way back into the kernel.
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74
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75 This code is believed to support all released Libc/Libsystem builds since
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76 Jaguar 6C115, including all the security updates. To be precise,
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77
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78 Libc Libsystem Build(s)
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79 262~1 60~37 6C115
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80 262~1 60.2~4 6D52
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81 262~1 61~3 6F21-6F22
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82 262~1 63~24 6G30-6G37
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83 262~1 63~32 6I34-6I35
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84 262~1 63~64 6L29-6L60
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85 262.4.1~1 63~84 6L123-6R172
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86
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87 320~1 71~101 7B85-7D28
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88 320~1 71~266 7F54-7F56
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89 320~1 71~288 7F112
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90 320~1 71~289 7F113
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91 320.1.3~1 71.1.1~29 7H60-7H105
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92 320.1.3~1 71.1.1~30 7H110-7H113
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93 320.1.3~1 71.1.1~31 7H114
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94
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95 That's a big table! It would be insane to try to keep track of
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96 every little detail, so we just read the code itself and do what
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97 it would do.
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98 */
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99
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100 for (;;)
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101 {
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102 uint32_t ins = *pc++;
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103
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104 if ((ins & 0xFC000003) == 0x48000000) /* b instruction */
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105 {
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106 pc += ((((int32_t) ins & 0x3FFFFFC) ^ 0x2000000) - 0x2000004) / 4;
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107 continue;
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108 }
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109 if ((ins & 0xFC600000) == 0x2C000000) /* cmpwi */
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110 {
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111 int32_t val1 = (int16_t) ins;
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112 int32_t val2 = gprs[ins >> 16 & 0x1F];
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113 /* Only beq and bne instructions are supported, so we only
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114 need to set the EQ bit. */
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115 uint32_t mask = 0xF << ((ins >> 21 & 0x1C) ^ 0x1C);
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116 if (val1 == val2)
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117 cr |= mask;
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118 else
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119 cr &= ~mask;
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120 continue;
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121 }
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122 if ((ins & 0xFEC38003) == 0x40820000) /* forwards beq/bne */
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123 {
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124 if ((cr >> ((ins >> 16 & 0x1F) ^ 0x1F) & 1) == (ins >> 24 & 1))
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125 pc += (ins & 0x7FFC) / 4 - 1;
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126 continue;
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127 }
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128 if ((ins & 0xFC0007FF) == 0x7C000378) /* or, including mr */
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129 {
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130 gprs [ins >> 16 & 0x1F] = (gprs [ins >> 11 & 0x1F]
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131 | gprs [ins >> 21 & 0x1F]);
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132 continue;
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133 }
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134 if (ins >> 26 == 0x0E) /* addi, including li */
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135 {
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136 reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
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137 gprs [ins >> 21 & 0x1F] = src + (int16_t) ins;
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138 continue;
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139 }
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140 if (ins >> 26 == 0x0F) /* addis, including lis */
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141 {
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142 reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
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143 gprs [ins >> 21 & 0x1F] = src + ((int16_t) ins << 16);
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144 continue;
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145 }
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146 if (ins >> 26 == 0x20) /* lwz */
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147 {
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148 reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
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149 uint32_t *p = (uint32_t *)(src + (int16_t) ins);
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150 if (p == invalid_address)
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151 return false;
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152 gprs [ins >> 21 & 0x1F] = *p;
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153 continue;
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154 }
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155 if (ins >> 26 == 0x21) /* lwzu */
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156 {
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157 uint32_t *p = (uint32_t *)(gprs [ins >> 16 & 0x1F] += (int16_t) ins);
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158 if (p == invalid_address)
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159 return false;
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160 gprs [ins >> 21 & 0x1F] = *p;
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161 continue;
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162 }
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163 if (ins >> 26 == 0x24) /* stw */
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164 /* What we hope this is doing is '--in_sigtramp'. We don't want
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165 to actually store to memory, so just make a note of the
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166 address and refuse to load from it. */
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167 {
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168 reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
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169 uint32_t *p = (uint32_t *)(src + (int16_t) ins);
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170 if (p == NULL || invalid_address != NULL)
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171 return false;
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172 invalid_address = p;
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173 continue;
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174 }
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175 if (ins >> 26 == 0x2E) /* lmw */
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176 {
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177 reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
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178 uint32_t *p = (uint32_t *)(src + (int16_t) ins);
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179 int i;
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180
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181 for (i = (ins >> 21 & 0x1F); i < 32; i++)
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182 {
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183 if (p == invalid_address)
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184 return false;
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185 gprs[i] = *p++;
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186 }
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187 continue;
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188 }
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189 if ((ins & 0xFC1FFFFF) == 0x7c0803a6) /* mtlr */
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190 {
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191 lr = gprs [ins >> 21 & 0x1F];
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192 continue;
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193 }
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194 if ((ins & 0xFC1FFFFF) == 0x7c0802a6) /* mflr */
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195 {
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196 gprs [ins >> 21 & 0x1F] = lr;
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197 continue;
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198 }
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199 if ((ins & 0xFC1FFFFF) == 0x7c0903a6) /* mtctr */
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200 {
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201 ctr = gprs [ins >> 21 & 0x1F];
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202 continue;
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203 }
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204 /* The PowerPC User's Manual says that bit 11 of the mtcrf
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205 instruction is reserved and should be set to zero, but it
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206 looks like the Darwin assembler doesn't do that... */
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207 if ((ins & 0xFC000FFF) == 0x7c000120) /* mtcrf */
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208 {
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209 int i;
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210 uint32_t mask = 0;
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211 for (i = 0; i < 8; i++)
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212 mask |= ((-(ins >> (12 + i) & 1)) & 0xF) << 4 * i;
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213 cr = (cr & ~mask) | (gprs [ins >> 21 & 0x1F] & mask);
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214 continue;
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215 }
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216 if (ins == 0x429f0005) /* bcl- 20,4*cr7+so,.+4, loads pc into LR */
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217 {
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218 lr = (reg_unit) pc;
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219 continue;
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220 }
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221 if (ins == 0x4e800420) /* bctr */
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222 {
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223 pc = (uint32_t *) ctr;
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224 continue;
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225 }
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226 if (ins == 0x44000002) /* sc */
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227 return true;
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228
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229 return false;
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230 }
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231 }
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232
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233 /* We used to include <ucontext.h> and <mach/thread_status.h>,
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234 but they change so much between different Darwin system versions
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235 that it's much easier to just write the structures involved here
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236 directly. */
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237
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238 /* These defines are from the kernel's bsd/dev/ppc/unix_signal.c. */
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239 #define UC_TRAD 1
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240 #define UC_TRAD_VEC 6
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241 #define UC_TRAD64 20
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242 #define UC_TRAD64_VEC 25
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243 #define UC_FLAVOR 30
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244 #define UC_FLAVOR_VEC 35
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245 #define UC_FLAVOR64 40
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246 #define UC_FLAVOR64_VEC 45
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247 #define UC_DUAL 50
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248 #define UC_DUAL_VEC 55
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249
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250 struct gcc_ucontext
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251 {
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252 int onstack;
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253 sigset_t sigmask;
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254 void * stack_sp;
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255 size_t stack_sz;
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256 int stack_flags;
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257 struct gcc_ucontext *link;
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258 size_t mcsize;
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259 struct gcc_mcontext32 *mcontext;
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260 };
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261
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262 struct gcc_float_vector_state
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263 {
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264 double fpregs[32];
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265 uint32_t fpscr_pad;
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266 uint32_t fpscr;
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267 uint32_t save_vr[32][4];
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268 uint32_t save_vscr[4];
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269 };
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270
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271 struct gcc_mcontext32 {
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272 uint32_t dar;
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273 uint32_t dsisr;
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274 uint32_t exception;
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275 uint32_t padding1[5];
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276 uint32_t srr0;
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277 uint32_t srr1;
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278 uint32_t gpr[32];
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279 uint32_t cr;
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280 uint32_t xer;
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281 uint32_t lr;
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282 uint32_t ctr;
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283 uint32_t mq;
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284 uint32_t vrsave;
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285 struct gcc_float_vector_state fvs;
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286 };
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287
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288 /* These are based on /usr/include/ppc/ucontext.h and
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289 /usr/include/mach/ppc/thread_status.h, but rewritten to be more
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290 convenient, to compile on Jaguar, and to work around Radar 3712064
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291 on Panther, which is that the 'es' field of 'struct mcontext64' has
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292 the wrong type (doh!). */
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293
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294 struct gcc_mcontext64 {
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295 uint64_t dar;
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296 uint32_t dsisr;
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297 uint32_t exception;
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298 uint32_t padding1[4];
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299 uint64_t srr0;
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300 uint64_t srr1;
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301 uint32_t gpr[32][2];
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302 uint32_t cr;
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303 uint32_t xer[2]; /* These are arrays because the original structure has them misaligned. */
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304 uint32_t lr[2];
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305 uint32_t ctr[2];
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306 uint32_t vrsave;
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307 struct gcc_float_vector_state fvs;
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308 };
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309
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310 #define UC_FLAVOR_SIZE \
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311 (sizeof (struct gcc_mcontext32) - 33*16)
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312
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313 #define UC_FLAVOR_VEC_SIZE (sizeof (struct gcc_mcontext32))
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314
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315 #define UC_FLAVOR64_SIZE \
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316 (sizeof (struct gcc_mcontext64) - 33*16)
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317
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318 #define UC_FLAVOR64_VEC_SIZE (sizeof (struct gcc_mcontext64))
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319
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320 /* Given GPRS as input to a 'sc' instruction, and OLD_CFA, update FS
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321 to represent the execution of a signal return; or, if not a signal
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322 return, return false. */
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323
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324 static bool
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325 handle_syscall (_Unwind_FrameState *fs, const reg_unit gprs[32],
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326 _Unwind_Ptr old_cfa)
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327 {
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328 struct gcc_ucontext *uctx;
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329 bool is_64, is_vector;
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330 struct gcc_float_vector_state * float_vector_state;
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331 _Unwind_Ptr new_cfa;
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332 int i;
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333 static _Unwind_Ptr return_addr;
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334
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335 /* Yay! We're in a Libc that we understand, and it's made a
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336 system call. In Jaguar, this is a direct system call with value 103;
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337 in Panther and Tiger it is a SYS_syscall call for system call number 184,
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338 and in Leopard it is a direct syscall with number 184. */
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339
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340 if (gprs[0] == 0x67 /* SYS_SIGRETURN */)
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341 {
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342 uctx = (struct gcc_ucontext *) gprs[3];
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343 is_vector = (uctx->mcsize == UC_FLAVOR64_VEC_SIZE
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344 || uctx->mcsize == UC_FLAVOR_VEC_SIZE);
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345 is_64 = (uctx->mcsize == UC_FLAVOR64_VEC_SIZE
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346 || uctx->mcsize == UC_FLAVOR64_SIZE);
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347 }
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348 else if (gprs[0] == 0 /* SYS_syscall */ && gprs[3] == 184)
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349 {
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350 int ctxstyle = gprs[5];
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351 uctx = (struct gcc_ucontext *) gprs[4];
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352 is_vector = (ctxstyle == UC_FLAVOR_VEC || ctxstyle == UC_FLAVOR64_VEC
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353 || ctxstyle == UC_TRAD_VEC || ctxstyle == UC_TRAD64_VEC);
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354 is_64 = (ctxstyle == UC_FLAVOR64_VEC || ctxstyle == UC_TRAD64_VEC
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355 || ctxstyle == UC_FLAVOR64 || ctxstyle == UC_TRAD64);
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356 }
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357 else if (gprs[0] == 184 /* SYS_sigreturn */)
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358 {
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359 int ctxstyle = gprs[4];
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360 uctx = (struct gcc_ucontext *) gprs[3];
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361 is_vector = (ctxstyle == UC_FLAVOR_VEC || ctxstyle == UC_FLAVOR64_VEC
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362 || ctxstyle == UC_TRAD_VEC || ctxstyle == UC_TRAD64_VEC);
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363 is_64 = (ctxstyle == UC_FLAVOR64_VEC || ctxstyle == UC_TRAD64_VEC
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364 || ctxstyle == UC_FLAVOR64 || ctxstyle == UC_TRAD64);
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365 }
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366 else
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367 return false;
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368
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369 #define set_offset(r, addr) \
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370 (fs->regs.reg[r].how = REG_SAVED_OFFSET, \
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371 fs->regs.reg[r].loc.offset = (_Unwind_Ptr)(addr) - new_cfa)
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372
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373 /* Restore even the registers that are not call-saved, since they
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374 might be being used in the prologue to save other registers,
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375 for instance GPR0 is sometimes used to save LR. */
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376
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377 /* Handle the GPRs, and produce the information needed to do the rest. */
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378 if (is_64)
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379 {
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380 /* The context is 64-bit, but it doesn't carry any extra information
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381 for us because only the low 32 bits of the registers are
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382 call-saved. */
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383 struct gcc_mcontext64 *m64 = (struct gcc_mcontext64 *)uctx->mcontext;
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384 int i;
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385
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386 float_vector_state = &m64->fvs;
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387
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388 new_cfa = m64->gpr[1][1];
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389
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390 set_offset (R_CR2, &m64->cr);
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391 for (i = 0; i < 32; i++)
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392 set_offset (i, m64->gpr[i] + 1);
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393 set_offset (R_XER, m64->xer + 1);
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394 set_offset (R_LR, m64->lr + 1);
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395 set_offset (R_CTR, m64->ctr + 1);
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396 if (is_vector)
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397 set_offset (R_VRSAVE, &m64->vrsave);
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398
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399 /* Sometimes, srr0 points to the instruction that caused the exception,
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400 and sometimes to the next instruction to be executed; we want
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401 the latter. */
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402 if (m64->exception == 3 || m64->exception == 4
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403 || m64->exception == 6
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404 || (m64->exception == 7 && !(m64->srr1 & 0x10000)))
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405 return_addr = m64->srr0 + 4;
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406 else
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407 return_addr = m64->srr0;
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408 }
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409 else
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410 {
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411 struct gcc_mcontext32 *m = uctx->mcontext;
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412 int i;
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413
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414 float_vector_state = &m->fvs;
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415
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416 new_cfa = m->gpr[1];
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417
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418 set_offset (R_CR2, &m->cr);
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419 for (i = 0; i < 32; i++)
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420 set_offset (i, m->gpr + i);
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421 set_offset (R_XER, &m->xer);
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422 set_offset (R_LR, &m->lr);
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423 set_offset (R_CTR, &m->ctr);
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424
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425 if (is_vector)
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426 set_offset (R_VRSAVE, &m->vrsave);
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427
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428 /* Sometimes, srr0 points to the instruction that caused the exception,
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429 and sometimes to the next instruction to be executed; we want
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430 the latter. */
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431 if (m->exception == 3 || m->exception == 4
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432 || m->exception == 6
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433 || (m->exception == 7 && !(m->srr1 & 0x10000)))
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434 return_addr = m->srr0 + 4;
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435 else
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436 return_addr = m->srr0;
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437 }
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438
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439 fs->regs.cfa_how = CFA_REG_OFFSET;
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440 fs->regs.cfa_reg = STACK_POINTER_REGNUM;
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441 fs->regs.cfa_offset = new_cfa - old_cfa;;
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442
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443 /* The choice of column for the return address is somewhat tricky.
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444 Fortunately, the actual choice is private to this file, and
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445 the space it's reserved from is the GCC register space, not the
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446 DWARF2 numbering. So any free element of the right size is an OK
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447 choice. Thus: */
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448 fs->retaddr_column = ARG_POINTER_REGNUM;
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449 /* FIXME: this should really be done using a DWARF2 location expression,
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450 not using a static variable. In fact, this entire file should
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451 be implemented in DWARF2 expressions. */
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452 set_offset (ARG_POINTER_REGNUM, &return_addr);
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453
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454 for (i = 0; i < 32; i++)
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455 set_offset (32 + i, float_vector_state->fpregs + i);
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456 set_offset (R_SPEFSCR, &float_vector_state->fpscr);
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457
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458 if (is_vector)
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459 {
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460 for (i = 0; i < 32; i++)
|
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461 set_offset (R_VR0 + i, float_vector_state->save_vr + i);
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462 set_offset (R_VSCR, float_vector_state->save_vscr);
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463 }
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464
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465 return true;
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466 }
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467
|
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468 /* This is also prototyped in rs6000/darwin.h, inside the
|
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469 MD_FALLBACK_FRAME_STATE_FOR macro. */
|
|
470 extern bool _Unwind_fallback_frame_state_for (struct _Unwind_Context *context,
|
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471 _Unwind_FrameState *fs);
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472
|
|
473 /* Implement the MD_FALLBACK_FRAME_STATE_FOR macro,
|
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474 returning true iff the frame was a sigreturn() frame that we
|
|
475 can understand. */
|
|
476
|
|
477 bool
|
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478 _Unwind_fallback_frame_state_for (struct _Unwind_Context *context,
|
|
479 _Unwind_FrameState *fs)
|
|
480 {
|
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481 reg_unit gprs[32];
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|
482
|
|
483 if (!interpret_libc (gprs, context))
|
|
484 return false;
|
|
485 return handle_syscall (fs, gprs, _Unwind_GetCFA (context));
|
|
486 }
|
|
487 #endif
|