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1 /* DWARF2 EH unwinding support for PA Linux.
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2 Copyright (C) 2004, 2005, 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
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7 it 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,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public 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
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26 /* Do code reading to identify a signal frame, and set the frame
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27 state data appropriately. See unwind-dw2.c for the structs. */
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28
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29 /* Don't use this if inhibit_libc is set.
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30 The build for this target will fail trying to include missing headers. */
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31 #ifndef inhibit_libc
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32 #include <signal.h>
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33 #include <sys/ucontext.h>
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34
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35 /* Unfortunately, because of various bugs and changes to the kernel,
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36 we have several cases to deal with.
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37
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38 In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should
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39 point directly at the beginning of the trampoline and struct rt_sigframe.
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40
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41 In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and
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42 (CONTEXT)->ra points at the 4th word in the trampoline structure. This
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43 is wrong, it should point at the 5th word. This is fixed in 2.6.5-rc2-pa4.
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44
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45 To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes
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46 to get the beginning of the signal frame, and then check offsets 0, 4
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47 and 5 to see if we found the beginning of the trampoline. This will
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48 tell us how to locate the sigcontext structure.
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49
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50 Note that with a 2.4 64-bit kernel, the signal context is not properly
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51 passed back to userspace so the unwind will not work correctly. */
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52
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53 #define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state
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54
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55 static _Unwind_Reason_Code
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56 pa32_fallback_frame_state (struct _Unwind_Context *context,
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57 _Unwind_FrameState *fs)
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58 {
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59 unsigned long sp = (unsigned long)context->ra & ~63;
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60 unsigned int *pc = (unsigned int *)sp;
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61 unsigned long off;
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62 _Unwind_Ptr new_cfa;
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63 int i;
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64 struct sigcontext *sc;
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65 struct rt_sigframe {
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66 struct siginfo info;
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67 struct ucontext uc;
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68 } *frame;
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69
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70 /* rt_sigreturn trampoline:
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71 3419000x ldi 0, %r25 or ldi 1, %r25 (x = 0 or 2)
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72 3414015a ldi __NR_rt_sigreturn, %r20
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73 e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31
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74 08000240 nop */
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75
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76 if (pc[0] == 0x34190000 || pc[0] == 0x34190002)
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77 off = 4*4;
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78 else if (pc[4] == 0x34190000 || pc[4] == 0x34190002)
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79 {
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80 pc += 4;
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81 off = 10 * 4;
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82 }
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83 else if (pc[5] == 0x34190000 || pc[5] == 0x34190002)
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84 {
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85 pc += 5;
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86 off = 10 * 4;
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87 }
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88 else
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89 {
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90 /* We may have to unwind through an alternate signal stack.
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91 We assume that the alignment of the alternate signal stack
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92 is BIGGEST_ALIGNMENT (i.e., that it has been allocated using
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93 malloc). As a result, we can't distinguish trampolines
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94 used prior to 2.6.5-rc2-pa4. However after 2.6.5-rc2-pa4,
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95 the return address of a signal trampoline will be on an odd
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96 word boundary and we can then determine the frame offset. */
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97 sp = (unsigned long)context->ra;
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98 pc = (unsigned int *)sp;
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99 if ((pc[0] == 0x34190000 || pc[0] == 0x34190002) && (sp & 4))
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100 off = 5 * 4;
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101 else
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102 return _URC_END_OF_STACK;
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103 }
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104
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105 if (pc[1] != 0x3414015a
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106 || pc[2] != 0xe4008200
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107 || pc[3] != 0x08000240)
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108 return _URC_END_OF_STACK;
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109
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110 frame = (struct rt_sigframe *)(sp + off);
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111 sc = &frame->uc.uc_mcontext;
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112
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113 new_cfa = sc->sc_gr[30];
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114 fs->regs.cfa_how = CFA_REG_OFFSET;
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115 fs->regs.cfa_reg = 30;
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116 fs->regs.cfa_offset = new_cfa - (long) context->cfa;
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117 for (i = 1; i <= 31; i++)
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118 {
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119 fs->regs.reg[i].how = REG_SAVED_OFFSET;
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120 fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
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121 }
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122 for (i = 4; i <= 31; i++)
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123 {
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124 /* FP regs have left and right halves */
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125 fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
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126 fs->regs.reg[2*i+24].loc.offset
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127 = (long)&sc->sc_fr[i] - new_cfa;
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128 fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
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129 fs->regs.reg[2*i+24+1].loc.offset
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130 = (long)&sc->sc_fr[i] + 4 - new_cfa;
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131 }
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132 fs->regs.reg[88].how = REG_SAVED_OFFSET;
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133 fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
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134 fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].how = REG_SAVED_OFFSET;
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135 fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].loc.offset
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136 = (long) &sc->sc_iaoq[0] - new_cfa;
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137 fs->retaddr_column = DWARF_ALT_FRAME_RETURN_COLUMN;
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138 return _URC_NO_REASON;
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139 }
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140 #endif /* inhibit_libc */
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