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1 /* DWARF2 EH unwinding support for TPF OS.
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2 Copyright (C) 2004, 2005, 2009 Free Software Foundation, Inc.
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3 Contributed by P.J. Darcy (darcypj@us.ibm.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 #include <dlfcn.h>
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27
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28 /* Function Name: __isPATrange
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29 Parameters passed into it: address to check
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30 Return Value: A 1 if address is in pat code "range", 0 if not
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31 Description: This function simply checks to see if the address
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32 passed to it is in the CP pat code range. */
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33
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34 #define MIN_PATRANGE 0x10000
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35 #define MAX_PATRANGE 0x800000
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36
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37 static inline unsigned int
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38 __isPATrange (void *addr)
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39 {
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40 if (addr > (void *)MIN_PATRANGE && addr < (void *)MAX_PATRANGE)
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41 return 1;
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42 else
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43 return 0;
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44 }
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45
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46 /* TPF return address offset from start of stack frame. */
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47 #define TPFRA_OFFSET 168
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48
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49 /* Exceptions macro defined for TPF so that functions without
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50 dwarf frame information can be used with exceptions. */
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51 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
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52
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53 static _Unwind_Reason_Code
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54 s390_fallback_frame_state (struct _Unwind_Context *context,
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55 _Unwind_FrameState *fs)
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56 {
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57 unsigned long int regs;
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58 unsigned long int new_cfa;
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59 int i;
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60
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61 regs = *((unsigned long int *)
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62 (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
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63
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64 /* Are we going through special linkage code? */
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65 if (__isPATrange (context->ra))
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66 {
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67
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68 /* Our return register isn't zero for end of stack, so
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69 check backward stackpointer to see if it is zero. */
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70 if (regs == NULL)
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71 return _URC_END_OF_STACK;
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72
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73 /* No stack frame. */
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74 fs->regs.cfa_how = CFA_REG_OFFSET;
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75 fs->regs.cfa_reg = 15;
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76 fs->regs.cfa_offset = STACK_POINTER_OFFSET;
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77
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78 /* All registers remain unchanged ... */
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79 for (i = 0; i < 32; i++)
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80 {
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81 fs->regs.reg[i].how = REG_SAVED_REG;
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82 fs->regs.reg[i].loc.reg = i;
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83 }
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84
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85 /* ... except for %r14, which is stored at CFA-112
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86 and used as return address. */
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87 fs->regs.reg[14].how = REG_SAVED_OFFSET;
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88 fs->regs.reg[14].loc.offset = TPFRA_OFFSET - STACK_POINTER_OFFSET;
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89 fs->retaddr_column = 14;
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90
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91 return _URC_NO_REASON;
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92 }
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93
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94 regs = *((unsigned long int *)
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95 (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
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96 new_cfa = regs + STACK_POINTER_OFFSET;
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97
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98 fs->regs.cfa_how = CFA_REG_OFFSET;
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99 fs->regs.cfa_reg = 15;
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100 fs->regs.cfa_offset = new_cfa -
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101 (unsigned long int) context->cfa + STACK_POINTER_OFFSET;
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102
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103 for (i = 0; i < 16; i++)
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104 {
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105 fs->regs.reg[i].how = REG_SAVED_OFFSET;
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106 fs->regs.reg[i].loc.offset = regs + i*8 - new_cfa;
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107 }
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108
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109 for (i = 0; i < 4; i++)
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110 {
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111 fs->regs.reg[16 + i].how = REG_SAVED_OFFSET;
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112 fs->regs.reg[16 + i].loc.offset = regs + 16*8 + i*8 - new_cfa;
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113 }
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114
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115 fs->retaddr_column = 14;
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116
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117 return _URC_NO_REASON;
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118 }
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119
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120 /* Function Name: __tpf_eh_return
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121 Parameters passed into it: Destination address to jump to.
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122 Return Value: Converted Destination address if a Pat Stub exists.
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123 Description: This function swaps the unwinding return address
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124 with the cp stub code. The original target return address is
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125 then stored into the tpf return address field. The cp stub
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126 code is searched for by climbing back up the stack and
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127 comparing the tpf stored return address object address to
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128 that of the targets object address. */
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129
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130 #define CURRENT_STACK_PTR() \
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131 ({ register unsigned long int *stack_ptr asm ("%r15"); stack_ptr; })
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132
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133 #define PREVIOUS_STACK_PTR() \
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134 ((unsigned long int *)(*(CURRENT_STACK_PTR())))
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135
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136 #define RA_OFFSET 112
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137 #define R15_OFFSET 120
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138 #define TPFAREA_OFFSET 160
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139 #define TPFAREA_SIZE STACK_POINTER_OFFSET-TPFAREA_OFFSET
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140 #define INVALID_RETURN 0
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141
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142 void * __tpf_eh_return (void *target);
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143
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144 void *
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145 __tpf_eh_return (void *target)
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146 {
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147 Dl_info targetcodeInfo, currentcodeInfo;
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148 int retval;
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149 void *current, *stackptr, *destination_frame;
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150 unsigned long int shifter, is_a_stub;
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151
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152 is_a_stub = 0;
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153
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154 /* Get code info for target return's address. */
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155 retval = dladdr (target, &targetcodeInfo);
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156
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157 /* Ensure the code info is valid (for target). */
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158 if (retval != INVALID_RETURN)
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159 {
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160
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161 /* Get the stack pointer of the stack frame to be modified by
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162 the exception unwinder. So that we can begin our climb
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163 there. */
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164 stackptr = (void *) *((unsigned long int *) (*(PREVIOUS_STACK_PTR())));
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165
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166 /* Begin looping through stack frames. Stop if invalid
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167 code information is retrieved or if a match between the
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168 current stack frame iteration shared object's address
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169 matches that of the target, calculated above. */
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170 do
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171 {
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172 /* Get return address based on our stackptr iterator. */
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173 current = (void *) *((unsigned long int *)
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174 (stackptr+RA_OFFSET));
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175
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176 /* Is it a Pat Stub? */
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177 if (__isPATrange (current))
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178 {
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179 /* Yes it was, get real return address
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180 in TPF stack area. */
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181 current = (void *) *((unsigned long int *)
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182 (stackptr+TPFRA_OFFSET));
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183 is_a_stub = 1;
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184 }
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185
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186 /* Get codeinfo on RA so that we can figure out
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187 the module address. */
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188 retval = dladdr (current, ¤tcodeInfo);
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189
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190 /* Check that codeinfo for current stack frame is valid.
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191 Then compare the module address of current stack frame
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192 to target stack frame to determine if we have the pat
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193 stub address we want. Also ensure we are dealing
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194 with a module crossing, stub return address. */
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195 if (is_a_stub && retval != INVALID_RETURN
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196 && targetcodeInfo.dli_fbase == currentcodeInfo.dli_fbase)
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197 {
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198 /* Yes! They are in the same module.
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199 Force copy of TPF private stack area to
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200 destination stack frame TPF private area. */
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201 destination_frame = (void *) *((unsigned long int *)
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202 (*PREVIOUS_STACK_PTR() + R15_OFFSET));
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203
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204 /* Copy TPF linkage area from current frame to
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205 destination frame. */
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206 memcpy((void *) (destination_frame + TPFAREA_OFFSET),
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207 (void *) (stackptr + TPFAREA_OFFSET), TPFAREA_SIZE);
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208
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209 /* Now overlay the
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210 real target address into the TPF stack area of
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211 the target frame we are jumping to. */
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212 *((unsigned long int *) (destination_frame +
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213 TPFRA_OFFSET)) = (unsigned long int) target;
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214
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215 /* Before returning the desired pat stub address to
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216 the exception handling unwinder so that it can
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217 actually do the "leap" shift out the low order
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218 bit designated to determine if we are in 64BIT mode.
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219 This is necessary for CTOA stubs.
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220 Otherwise we leap one byte past where we want to
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221 go to in the TPF pat stub linkage code. */
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222 shifter = *((unsigned long int *)
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223 (stackptr + RA_OFFSET));
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224
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225 shifter &= ~1ul;
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226
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227 /* Store Pat Stub Address in destination Stack Frame. */
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228 *((unsigned long int *) (destination_frame +
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229 RA_OFFSET)) = shifter;
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230
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231 /* Re-adjust pat stub address to go to correct place
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232 in linkage. */
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233 shifter = shifter - 4;
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234
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235 return (void *) shifter;
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236 }
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237
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238 /* Desired module pat stub not found ...
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239 Bump stack frame iterator. */
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240 stackptr = (void *) *(unsigned long int *) stackptr;
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241
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242 is_a_stub = 0;
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243
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244 } while (stackptr && retval != INVALID_RETURN
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245 && targetcodeInfo.dli_fbase != currentcodeInfo.dli_fbase);
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246 }
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247
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248 /* No pat stub found, could be a problem? Simply return unmodified
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249 target address. */
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250 return target;
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251 }
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252
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