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111
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1 /* go-unwind.c -- unwind the stack for panic/recover.
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2
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3 Copyright 2010 The Go Authors. All rights reserved.
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4 Use of this source code is governed by a BSD-style
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5 license that can be found in the LICENSE file. */
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6
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7 #include "config.h"
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8
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9 #include <stdlib.h>
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10 #include <unistd.h>
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11
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12 #include "unwind.h"
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13
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14 #include "runtime.h"
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15
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131
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16 /* These constants are documented here:
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17 https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA/dwarfext.html
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18 */
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19
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20 #define DW_EH_PE_omit 0xff
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21 #define DW_EH_PE_absptr 0x00
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22 #define DW_EH_PE_uleb128 0x01
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23 #define DW_EH_PE_udata2 0x02
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24 #define DW_EH_PE_udata4 0x03
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25 #define DW_EH_PE_udata8 0x04
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26 #define DW_EH_PE_sleb128 0x09
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27 #define DW_EH_PE_sdata2 0x0A
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28 #define DW_EH_PE_sdata4 0x0B
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29 #define DW_EH_PE_sdata8 0x0C
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30 #define DW_EH_PE_pcrel 0x10
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31 #define DW_EH_PE_textrel 0x20
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32 #define DW_EH_PE_datarel 0x30
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33 #define DW_EH_PE_funcrel 0x40
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34 #define DW_EH_PE_aligned 0x50
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35 #define DW_EH_PE_indirect 0x80
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36
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111
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37 /* The code for a Go exception. */
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38
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39 #ifdef __ARM_EABI_UNWINDER__
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40 static const _Unwind_Exception_Class __go_exception_class =
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41 { 'G', 'N', 'U', 'C', 'G', 'O', '\0', '\0' };
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42 #else
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43 static const _Unwind_Exception_Class __go_exception_class =
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44 ((((((((_Unwind_Exception_Class) 'G'
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45 << 8 | (_Unwind_Exception_Class) 'N')
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46 << 8 | (_Unwind_Exception_Class) 'U')
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47 << 8 | (_Unwind_Exception_Class) 'C')
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48 << 8 | (_Unwind_Exception_Class) 'G')
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49 << 8 | (_Unwind_Exception_Class) 'O')
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50 << 8 | (_Unwind_Exception_Class) '\0')
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51 << 8 | (_Unwind_Exception_Class) '\0');
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52 #endif
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53
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54 /* Rethrow an exception. */
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55
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56 void rethrowException (void) __asm__(GOSYM_PREFIX "runtime.rethrowException");
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57
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58 void
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59 rethrowException ()
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60 {
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61 struct _Unwind_Exception *hdr;
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62
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63 hdr = (struct _Unwind_Exception *) runtime_g()->exception;
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64
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65 #ifdef __USING_SJLJ_EXCEPTIONS__
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66 _Unwind_SjLj_Resume_or_Rethrow (hdr);
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67 #else
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68 #if defined(_LIBUNWIND_STD_ABI)
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69 _Unwind_RaiseException (hdr);
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70 #else
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71 _Unwind_Resume_or_Rethrow (hdr);
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72 #endif
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73 #endif
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74
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75 /* Rethrowing the exception should not return. */
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76 abort();
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77 }
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78
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79 /* Return the size of the type that holds an exception header, so that
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80 it can be allocated by Go code. */
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81
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82 uintptr unwindExceptionSize(void)
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83 __asm__ (GOSYM_PREFIX "runtime.unwindExceptionSize");
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84
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85 uintptr
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86 unwindExceptionSize ()
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87 {
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88 uintptr ret, align;
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89
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90 ret = sizeof (struct _Unwind_Exception);
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91 /* Adjust the size fo make sure that we can get an aligned value. */
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92 align = __alignof__ (struct _Unwind_Exception);
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93 if (align > __alignof__ (uintptr))
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94 ret += align - __alignof__ (uintptr);
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95 return ret;
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96 }
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97
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98 /* Throw an exception. This is called with g->exception pointing to
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99 an uninitialized _Unwind_Exception instance. */
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100
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101 void throwException (void) __asm__(GOSYM_PREFIX "runtime.throwException");
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102
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103 void
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104 throwException ()
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105 {
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106 struct _Unwind_Exception *hdr;
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107 uintptr align;
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108
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109 hdr = (struct _Unwind_Exception *)runtime_g ()->exception;
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110
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111 /* Make sure the value is correctly aligned. It will be large
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112 enough, because of unwindExceptionSize. */
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113 align = __alignof__ (struct _Unwind_Exception);
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114 hdr = ((struct _Unwind_Exception *)
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115 (((uintptr) hdr + align - 1) &~ (align - 1)));
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116
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117 __builtin_memcpy (&hdr->exception_class, &__go_exception_class,
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118 sizeof hdr->exception_class);
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119 hdr->exception_cleanup = NULL;
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120
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121 #ifdef __USING_SJLJ_EXCEPTIONS__
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122 _Unwind_SjLj_RaiseException (hdr);
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123 #else
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124 _Unwind_RaiseException (hdr);
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125 #endif
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126
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127 /* Raising an exception should not return. */
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128 abort ();
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129 }
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130
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131
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131 static inline _Unwind_Ptr
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132 encoded_value_base (uint8_t encoding, struct _Unwind_Context *context)
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133 {
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134 if (encoding == DW_EH_PE_omit)
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135 return 0;
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136 switch (encoding & 0x70)
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137 {
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138 case DW_EH_PE_absptr:
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139 case DW_EH_PE_pcrel:
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140 case DW_EH_PE_aligned:
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141 return 0;
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142 case DW_EH_PE_textrel:
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143 return _Unwind_GetTextRelBase(context);
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144 case DW_EH_PE_datarel:
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145 return _Unwind_GetDataRelBase(context);
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146 case DW_EH_PE_funcrel:
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147 return _Unwind_GetRegionStart(context);
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148 }
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149 abort ();
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150 }
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151
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152 /* Read an unsigned leb128 value. */
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153
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154 static inline const uint8_t *
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155 read_uleb128 (const uint8_t *p, _uleb128_t *val)
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156 {
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157 unsigned int shift = 0;
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158 _uleb128_t result = 0;
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159 uint8_t byte;
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160
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161 do
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162 {
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163 byte = *p++;
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164 result |= ((_uleb128_t)byte & 0x7f) << shift;
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165 shift += 7;
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166 }
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167 while (byte & 0x80);
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168
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169 *val = result;
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170 return p;
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171 }
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172
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173 /* Similar, but read a signed leb128 value. */
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174
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175 static inline const uint8_t *
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176 read_sleb128 (const uint8_t *p, _sleb128_t *val)
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177 {
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178 unsigned int shift = 0;
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179 _uleb128_t result = 0;
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180 uint8_t byte;
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181
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182 do
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183 {
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184 byte = *p++;
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185 result |= ((_uleb128_t)byte & 0x7f) << shift;
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186 shift += 7;
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187 }
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188 while (byte & 0x80);
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189
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190 /* sign extension */
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191 if (shift < (8 * sizeof(result)) && (byte & 0x40) != 0)
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192 result |= (((_uleb128_t)~0) << shift);
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193
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194 *val = (_sleb128_t)result;
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195 return p;
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196 }
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197
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198 #define ROUND_UP_TO_PVB(x) (x + sizeof(void *) - 1) &- sizeof(void *)
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199
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200 static inline const uint8_t *
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201 read_encoded_value (struct _Unwind_Context *context, uint8_t encoding,
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202 const uint8_t *p, _Unwind_Ptr *val)
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203 {
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204 _Unwind_Ptr base = encoded_value_base (encoding, context);
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205 _Unwind_Internal_Ptr decoded = 0;
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206 const uint8_t *origp = p;
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207
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208 if (encoding == DW_EH_PE_aligned)
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209 {
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210 _Unwind_Internal_Ptr uip = (_Unwind_Internal_Ptr)p;
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211 uip = ROUND_UP_TO_PVB (uip);
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212 decoded = *(_Unwind_Internal_Ptr *)uip;
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213 p = (const uint8_t *)(uip + sizeof(void *));
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214 }
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215 else
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216 {
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217 switch (encoding & 0x0f)
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218 {
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219 case DW_EH_PE_sdata2:
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220 {
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221 int16_t result;
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222 __builtin_memcpy (&result, p, sizeof(int16_t));
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223 decoded = result;
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224 p += sizeof(int16_t);
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225 break;
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226 }
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227 case DW_EH_PE_udata2:
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228 {
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229 uint16_t result;
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230 __builtin_memcpy (&result, p, sizeof(uint16_t));
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231 decoded = result;
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232 p += sizeof(uint16_t);
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233 break;
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234 }
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235 case DW_EH_PE_sdata4:
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236 {
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237 int32_t result;
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238 __builtin_memcpy (&result, p, sizeof(int32_t));
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239 decoded = result;
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240 p += sizeof(int32_t);
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241 break;
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242 }
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243 case DW_EH_PE_udata4:
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244 {
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245 uint32_t result;
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246 __builtin_memcpy (&result, p, sizeof(uint32_t));
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247 decoded = result;
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248 p += sizeof(uint32_t);
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249 break;
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250 }
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251 case DW_EH_PE_sdata8:
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252 {
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253 int64_t result;
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254 __builtin_memcpy (&result, p, sizeof(int64_t));
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255 decoded = result;
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256 p += sizeof(int64_t);
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257 break;
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258 }
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259 case DW_EH_PE_udata8:
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260 {
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261 uint64_t result;
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262 __builtin_memcpy (&result, p, sizeof(uint64_t));
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263 decoded = result;
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264 p += sizeof(uint64_t);
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265 break;
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266 }
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267 case DW_EH_PE_uleb128:
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268 {
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269 _uleb128_t value;
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270 p = read_uleb128 (p, &value);
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271 decoded = (_Unwind_Internal_Ptr)value;
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272 break;
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273 }
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274 case DW_EH_PE_sleb128:
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275 {
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276 _sleb128_t value;
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277 p = read_sleb128 (p, &value);
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278 decoded = (_Unwind_Internal_Ptr)value;
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279 break;
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280 }
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281 case DW_EH_PE_absptr:
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282 __builtin_memcpy (&decoded, (const void *)p, sizeof(const void*));
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283 p += sizeof(void *);
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284 break;
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285 default:
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286 abort ();
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287 }
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288
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289 if (decoded == 0)
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290 {
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291 *val = decoded;
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292 return p;
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293 }
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294
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295 if ((encoding & 0x70) == DW_EH_PE_pcrel)
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296 decoded += ((_Unwind_Internal_Ptr)origp);
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297 else
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298 decoded += base;
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299
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300 if ((encoding & DW_EH_PE_indirect) != 0)
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301 decoded = *(_Unwind_Internal_Ptr *)decoded;
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302 }
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303 *val = decoded;
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304 return p;
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305 }
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306
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145
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307 static inline int
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308 value_size (uint8_t encoding)
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309 {
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310 switch (encoding & 0x0f)
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311 {
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312 case DW_EH_PE_sdata2:
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313 case DW_EH_PE_udata2:
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314 return 2;
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315 case DW_EH_PE_sdata4:
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316 case DW_EH_PE_udata4:
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317 return 4;
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318 case DW_EH_PE_sdata8:
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319 case DW_EH_PE_udata8:
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320 return 8;
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321 case DW_EH_PE_absptr:
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322 return sizeof(uintptr);
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323 default:
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324 break;
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325 }
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326 abort ();
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327 }
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328
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111
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329 /* The rest of this code is really similar to gcc/unwind-c.c and
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330 libjava/exception.cc. */
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331
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332 typedef struct
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333 {
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334 _Unwind_Ptr Start;
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335 _Unwind_Ptr LPStart;
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336 _Unwind_Ptr ttype_base;
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337 const unsigned char *TType;
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338 const unsigned char *action_table;
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339 unsigned char ttype_encoding;
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340 unsigned char call_site_encoding;
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341 } lsda_header_info;
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342
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343 static const unsigned char *
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344 parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p,
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345 lsda_header_info *info)
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346 {
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347 _uleb128_t tmp;
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348 unsigned char lpstart_encoding;
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349
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350 info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
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351
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352 /* Find @LPStart, the base to which landing pad offsets are relative. */
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353 lpstart_encoding = *p++;
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354 if (lpstart_encoding != DW_EH_PE_omit)
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355 p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
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356 else
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357 info->LPStart = info->Start;
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358
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359 /* Find @TType, the base of the handler and exception spec type data. */
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360 info->ttype_encoding = *p++;
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361 if (info->ttype_encoding != DW_EH_PE_omit)
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362 {
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363 p = read_uleb128 (p, &tmp);
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364 info->TType = p + tmp;
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365 }
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366 else
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367 info->TType = 0;
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368
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369 /* The encoding and length of the call-site table; the action table
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370 immediately follows. */
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371 info->call_site_encoding = *p++;
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372 p = read_uleb128 (p, &tmp);
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373 info->action_table = p + tmp;
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374
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375 return p;
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376 }
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377
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378 /* The personality function is invoked when unwinding the stack due to
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379 a panic. Its job is to find the cleanup and exception handlers to
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380 run. We can't split the stack here, because we won't be able to
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381 unwind from that split. */
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382
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383 #ifdef __ARM_EABI_UNWINDER__
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384 /* ARM EABI personality routines must also unwind the stack. */
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385 #define CONTINUE_UNWINDING \
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386 do \
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387 { \
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388 if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \
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389 return _URC_FAILURE; \
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390 return _URC_CONTINUE_UNWIND; \
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391 } \
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392 while (0)
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393 #else
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394 #define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
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395 #endif
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396
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145
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397 #ifdef __ARM_EABI_UNWINDER__
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398 #define STOP_UNWINDING _URC_FAILURE
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399 #else
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400 #define STOP_UNWINDING _URC_NORMAL_STOP
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401 #endif
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402
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111
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403 #ifdef __USING_SJLJ_EXCEPTIONS__
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404 #define PERSONALITY_FUNCTION __gccgo_personality_sj0
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405 #define __builtin_eh_return_data_regno(x) x
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406 #else
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407 #define PERSONALITY_FUNCTION __gccgo_personality_v0
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408 #endif
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409
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410 #ifdef __ARM_EABI_UNWINDER__
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411 _Unwind_Reason_Code
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412 PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *,
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413 struct _Unwind_Context *)
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145
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414 __attribute__ ((no_split_stack, flatten, target ("general-regs-only")));
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111
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415
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416 _Unwind_Reason_Code
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417 PERSONALITY_FUNCTION (_Unwind_State state,
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|
418 struct _Unwind_Exception * ue_header,
|
|
|
419 struct _Unwind_Context * context)
|
|
|
420 #else
|
|
|
421 _Unwind_Reason_Code
|
|
|
422 PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,
|
|
|
423 struct _Unwind_Exception *, struct _Unwind_Context *)
|
|
|
424 __attribute__ ((no_split_stack, flatten));
|
|
|
425
|
|
|
426 _Unwind_Reason_Code
|
|
|
427 PERSONALITY_FUNCTION (int version,
|
|
|
428 _Unwind_Action actions,
|
|
|
429 _Unwind_Exception_Class exception_class,
|
|
|
430 struct _Unwind_Exception *ue_header,
|
|
|
431 struct _Unwind_Context *context)
|
|
|
432 #endif
|
|
|
433 {
|
|
|
434 lsda_header_info info;
|
|
|
435 const unsigned char *language_specific_data, *p, *action_record;
|
|
|
436 _Unwind_Ptr landing_pad, ip;
|
|
|
437 int ip_before_insn = 0;
|
|
|
438 _Bool is_foreign;
|
|
|
439 G *g;
|
|
|
440
|
|
|
441 #ifdef __ARM_EABI_UNWINDER__
|
|
|
442 _Unwind_Action actions;
|
|
|
443
|
|
|
444 switch (state & _US_ACTION_MASK)
|
|
|
445 {
|
|
|
446 case _US_VIRTUAL_UNWIND_FRAME:
|
|
145
|
447 if (state & _UA_FORCE_UNWIND)
|
|
|
448 /* We are called from _Unwind_Backtrace. No handler to run. */
|
|
|
449 CONTINUE_UNWINDING;
|
|
111
|
450 actions = _UA_SEARCH_PHASE;
|
|
|
451 break;
|
|
|
452
|
|
|
453 case _US_UNWIND_FRAME_STARTING:
|
|
|
454 actions = _UA_CLEANUP_PHASE;
|
|
|
455 if (!(state & _US_FORCE_UNWIND)
|
|
|
456 && ue_header->barrier_cache.sp == _Unwind_GetGR(context, 13))
|
|
|
457 actions |= _UA_HANDLER_FRAME;
|
|
|
458 break;
|
|
|
459
|
|
|
460 case _US_UNWIND_FRAME_RESUME:
|
|
|
461 CONTINUE_UNWINDING;
|
|
|
462 break;
|
|
|
463
|
|
|
464 default:
|
|
|
465 abort();
|
|
|
466 }
|
|
|
467 actions |= state & _US_FORCE_UNWIND;
|
|
|
468
|
|
|
469 is_foreign = 0;
|
|
|
470
|
|
|
471 /* The dwarf unwinder assumes the context structure holds things like the
|
|
|
472 function and LSDA pointers. The ARM implementation caches these in
|
|
|
473 the exception header (UCB). To avoid rewriting everything we make the
|
|
|
474 virtual IP register point at the UCB. */
|
|
|
475 ip = (_Unwind_Ptr) ue_header;
|
|
|
476 _Unwind_SetGR (context, 12, ip);
|
|
|
477 #else
|
|
|
478 if (version != 1)
|
|
|
479 return _URC_FATAL_PHASE1_ERROR;
|
|
|
480
|
|
|
481 is_foreign = exception_class != __go_exception_class;
|
|
|
482 #endif
|
|
|
483
|
|
|
484 language_specific_data = (const unsigned char *)
|
|
|
485 _Unwind_GetLanguageSpecificData (context);
|
|
|
486
|
|
|
487 /* If no LSDA, then there are no handlers or cleanups. */
|
|
|
488 if (! language_specific_data)
|
|
|
489 CONTINUE_UNWINDING;
|
|
|
490
|
|
|
491 /* Parse the LSDA header. */
|
|
|
492 p = parse_lsda_header (context, language_specific_data, &info);
|
|
|
493 #ifdef HAVE_GETIPINFO
|
|
|
494 ip = _Unwind_GetIPInfo (context, &ip_before_insn);
|
|
|
495 #else
|
|
|
496 ip = _Unwind_GetIP (context);
|
|
|
497 #endif
|
|
|
498 if (! ip_before_insn)
|
|
|
499 --ip;
|
|
|
500 landing_pad = 0;
|
|
|
501 action_record = NULL;
|
|
|
502
|
|
|
503 #ifdef __USING_SJLJ_EXCEPTIONS__
|
|
|
504 /* The given "IP" is an index into the call-site table, with two
|
|
|
505 exceptions -- -1 means no-action, and 0 means terminate. But
|
|
|
506 since we're using uleb128 values, we've not got random access
|
|
|
507 to the array. */
|
|
|
508 if ((int) ip <= 0)
|
|
|
509 return _URC_CONTINUE_UNWIND;
|
|
|
510 else
|
|
|
511 {
|
|
|
512 _uleb128_t cs_lp, cs_action;
|
|
|
513 do
|
|
|
514 {
|
|
|
515 p = read_uleb128 (p, &cs_lp);
|
|
|
516 p = read_uleb128 (p, &cs_action);
|
|
|
517 }
|
|
|
518 while (--ip);
|
|
|
519
|
|
|
520 /* Can never have null landing pad for sjlj -- that would have
|
|
|
521 been indicated by a -1 call site index. */
|
|
|
522 landing_pad = (_Unwind_Ptr)cs_lp + 1;
|
|
|
523 if (cs_action)
|
|
|
524 action_record = info.action_table + cs_action - 1;
|
|
|
525 goto found_something;
|
|
|
526 }
|
|
|
527 #else
|
|
|
528 /* Search the call-site table for the action associated with this IP. */
|
|
|
529 while (p < info.action_table)
|
|
|
530 {
|
|
|
531 _Unwind_Ptr cs_start, cs_len, cs_lp;
|
|
|
532 _uleb128_t cs_action;
|
|
|
533
|
|
|
534 /* Note that all call-site encodings are "absolute" displacements. */
|
|
|
535 p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
|
|
|
536 p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
|
|
|
537 p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
|
|
|
538 p = read_uleb128 (p, &cs_action);
|
|
|
539
|
|
|
540 /* The table is sorted, so if we've passed the ip, stop. */
|
|
|
541 if (ip < info.Start + cs_start)
|
|
|
542 p = info.action_table;
|
|
|
543 else if (ip < info.Start + cs_start + cs_len)
|
|
|
544 {
|
|
|
545 if (cs_lp)
|
|
|
546 landing_pad = info.LPStart + cs_lp;
|
|
|
547 if (cs_action)
|
|
|
548 action_record = info.action_table + cs_action - 1;
|
|
|
549 goto found_something;
|
|
|
550 }
|
|
|
551 }
|
|
|
552 #endif
|
|
|
553
|
|
|
554 /* IP is not in table. No associated cleanups. */
|
|
|
555 CONTINUE_UNWINDING;
|
|
|
556
|
|
|
557 found_something:
|
|
|
558 if (landing_pad == 0)
|
|
|
559 {
|
|
|
560 /* IP is present, but has a null landing pad.
|
|
|
561 No handler to be run. */
|
|
|
562 CONTINUE_UNWINDING;
|
|
|
563 }
|
|
|
564
|
|
|
565 if (actions & _UA_SEARCH_PHASE)
|
|
|
566 {
|
|
|
567 if (action_record == 0)
|
|
|
568 {
|
|
|
569 /* This indicates a cleanup rather than an exception
|
|
|
570 handler. */
|
|
|
571 CONTINUE_UNWINDING;
|
|
|
572 }
|
|
|
573
|
|
|
574 return _URC_HANDLER_FOUND;
|
|
|
575 }
|
|
|
576
|
|
|
577 /* It's possible for g to be NULL here for an exception thrown by a
|
|
|
578 language other than Go. */
|
|
|
579 g = runtime_g ();
|
|
|
580 if (g == NULL)
|
|
|
581 {
|
|
|
582 if (!is_foreign)
|
|
|
583 abort ();
|
|
|
584 }
|
|
|
585 else
|
|
|
586 {
|
|
|
587 g->exception = ue_header;
|
|
|
588 g->isforeign = is_foreign;
|
|
|
589 }
|
|
|
590
|
|
|
591 _Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
|
|
|
592 (_Unwind_Ptr) ue_header);
|
|
|
593 _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);
|
|
|
594 _Unwind_SetIP (context, landing_pad);
|
|
|
595 return _URC_INSTALL_CONTEXT;
|
|
|
596 }
|
|
145
|
597
|
|
|
598 // A dummy personality function, which doesn't capture any exception
|
|
|
599 // and simply passes by. This is used for functions that don't
|
|
|
600 // capture exceptions but need LSDA for stack maps.
|
|
|
601 _Unwind_Reason_Code
|
|
|
602 __gccgo_personality_dummy (int, _Unwind_Action, _Unwind_Exception_Class,
|
|
|
603 struct _Unwind_Exception *, struct _Unwind_Context *)
|
|
|
604 __attribute__ ((no_split_stack));
|
|
|
605
|
|
|
606 _Unwind_Reason_Code
|
|
|
607 #ifdef __ARM_EABI_UNWINDER__
|
|
|
608 __attribute__ ((target ("general-regs-only")))
|
|
|
609 #endif
|
|
|
610 __gccgo_personality_dummy (int version __attribute__ ((unused)),
|
|
|
611 _Unwind_Action actions __attribute__ ((unused)),
|
|
|
612 _Unwind_Exception_Class exception_class __attribute__ ((unused)),
|
|
|
613 struct _Unwind_Exception *ue_header __attribute__ ((unused)),
|
|
|
614 struct _Unwind_Context *context __attribute__ ((unused)))
|
|
|
615 {
|
|
|
616 CONTINUE_UNWINDING;
|
|
|
617 }
|
|
|
618
|
|
|
619 // A sentinel value for Go functions.
|
|
|
620 // A function is a Go function if it has LSDA, which has type info,
|
|
|
621 // and the first (dummy) landing pad's type info is a pointer to
|
|
|
622 // this value.
|
|
|
623 #define GO_FUNC_SENTINEL ((uint64)'G' | ((uint64)'O'<<8) | \
|
|
|
624 ((uint64)'.'<<16) | ((uint64)'.'<<24) | \
|
|
|
625 ((uint64)'F'<<32) | ((uint64)'U'<<40) | \
|
|
|
626 ((uint64)'N'<<48) | ((uint64)'C'<<56))
|
|
|
627
|
|
|
628 struct _stackmap {
|
|
|
629 uint32 len;
|
|
|
630 uint8 data[1]; // variabe length
|
|
|
631 };
|
|
|
632
|
|
|
633 extern void
|
|
|
634 runtime_scanstackblockwithmap (uintptr ip, uintptr sp, uintptr size, uint8 *ptrmask, void* gcw)
|
|
|
635 __asm__ (GOSYM_PREFIX "runtime.scanstackblockwithmap");
|
|
|
636
|
|
|
637 #define FOUND 0
|
|
|
638 #define NOTFOUND_OK 1
|
|
|
639 #define NOTFOUND_BAD 2
|
|
|
640
|
|
|
641 // Helper function to search for stack maps in the unwinding records of a frame.
|
|
|
642 // If found, populate ip, sp, and stackmap. Returns the #define'd values above.
|
|
|
643 static int
|
|
|
644 findstackmaps (struct _Unwind_Context *context, _Unwind_Ptr *ip, _Unwind_Ptr *sp, struct _stackmap **stackmap)
|
|
|
645 {
|
|
|
646 lsda_header_info info;
|
|
|
647 const unsigned char *language_specific_data, *p, *action_record;
|
|
|
648 bool first;
|
|
|
649 struct _stackmap *stackmap1;
|
|
|
650 _Unwind_Ptr ip1;
|
|
|
651 int ip_before_insn = 0;
|
|
|
652 _sleb128_t index;
|
|
|
653 int size;
|
|
|
654
|
|
|
655 #ifdef HAVE_GETIPINFO
|
|
|
656 ip1 = _Unwind_GetIPInfo (context, &ip_before_insn);
|
|
|
657 #else
|
|
|
658 ip1 = _Unwind_GetIP (context);
|
|
|
659 #endif
|
|
|
660 if (! ip_before_insn)
|
|
|
661 --ip1;
|
|
|
662
|
|
|
663 if (ip != NULL)
|
|
|
664 *ip = ip1;
|
|
|
665 if (sp != NULL)
|
|
|
666 *sp = _Unwind_GetCFA (context);
|
|
|
667
|
|
|
668 #ifdef __ARM_EABI_UNWINDER__
|
|
|
669 {
|
|
|
670 _Unwind_Control_Block *ucbp;
|
|
|
671 ucbp = (_Unwind_Control_Block *) _Unwind_GetGR (context, 12);
|
|
|
672 if (*ucbp->pr_cache.ehtp & (1u << 31))
|
|
|
673 // The "compact" model is used, with one of the predefined
|
|
|
674 // personality functions. It doesn't have standard LSDA.
|
|
|
675 return NOTFOUND_OK;
|
|
|
676 }
|
|
|
677 #endif
|
|
|
678
|
|
|
679 language_specific_data = (const unsigned char *)
|
|
|
680 _Unwind_GetLanguageSpecificData (context);
|
|
|
681
|
|
|
682 /* If no LSDA, then there is no stack maps. */
|
|
|
683 if (! language_specific_data)
|
|
|
684 return NOTFOUND_OK;
|
|
|
685
|
|
|
686 p = parse_lsda_header (context, language_specific_data, &info);
|
|
|
687
|
|
|
688 if (info.TType == NULL)
|
|
|
689 return NOTFOUND_OK;
|
|
|
690
|
|
|
691 size = value_size (info.ttype_encoding);
|
|
|
692
|
|
|
693 action_record = NULL;
|
|
|
694 first = true;
|
|
|
695
|
|
|
696 /* Search the call-site table for the action associated with this IP. */
|
|
|
697 while (p < info.action_table)
|
|
|
698 {
|
|
|
699 _Unwind_Ptr cs_start, cs_len, cs_lp;
|
|
|
700 _uleb128_t cs_action;
|
|
|
701
|
|
|
702 /* Note that all call-site encodings are "absolute" displacements. */
|
|
|
703 p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
|
|
|
704 p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
|
|
|
705 p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
|
|
|
706 p = read_uleb128 (p, &cs_action);
|
|
|
707
|
|
|
708 if (first)
|
|
|
709 {
|
|
|
710 // For a Go function, the first entry points to the sentinel value.
|
|
|
711 // Check this here.
|
|
|
712 const unsigned char *p1, *action1;
|
|
|
713 uint64 *x;
|
|
|
714
|
|
|
715 if (!cs_action)
|
|
|
716 return NOTFOUND_OK;
|
|
|
717
|
|
|
718 action1 = info.action_table + cs_action - 1;
|
|
|
719 read_sleb128 (action1, &index);
|
|
|
720 p1 = info.TType - index*size;
|
|
|
721 read_encoded_value (context, info.ttype_encoding, p1, (_Unwind_Ptr*)&x);
|
|
|
722 if (x == NULL || *x != GO_FUNC_SENTINEL)
|
|
|
723 return NOTFOUND_OK;
|
|
|
724
|
|
|
725 first = false;
|
|
|
726 continue;
|
|
|
727 }
|
|
|
728
|
|
|
729 /* The table is sorted, so if we've passed the ip, stop. */
|
|
|
730 if (ip1 < info.Start + cs_start)
|
|
|
731 return NOTFOUND_BAD;
|
|
|
732 else if (ip1 < info.Start + cs_start + cs_len)
|
|
|
733 {
|
|
|
734 if (cs_action)
|
|
|
735 action_record = info.action_table + cs_action - 1;
|
|
|
736 break;
|
|
|
737 }
|
|
|
738 }
|
|
|
739
|
|
|
740 if (action_record == NULL)
|
|
|
741 return NOTFOUND_BAD;
|
|
|
742
|
|
|
743 read_sleb128 (action_record, &index);
|
|
|
744 p = info.TType - index*size;
|
|
|
745 read_encoded_value (context, info.ttype_encoding, p, (_Unwind_Ptr*)&stackmap1);
|
|
|
746 if (stackmap1 == NULL)
|
|
|
747 return NOTFOUND_BAD;
|
|
|
748
|
|
|
749 if (stackmap != NULL)
|
|
|
750 *stackmap = stackmap1;
|
|
|
751 return FOUND;
|
|
|
752 }
|
|
|
753
|
|
|
754 struct scanstate {
|
|
|
755 void* gcw; // the GC worker, passed into scanstackwithmap_callback
|
|
|
756 uintptr lastsp; // the last (outermost) SP of Go function seen in a traceback, set by the callback
|
|
|
757 };
|
|
|
758
|
|
|
759 // Callback function to scan a stack frame with stack maps.
|
|
|
760 // It skips non-Go functions.
|
|
|
761 static _Unwind_Reason_Code
|
|
|
762 scanstackwithmap_callback (struct _Unwind_Context *context, void *arg)
|
|
|
763 {
|
|
|
764 struct _stackmap *stackmap;
|
|
|
765 _Unwind_Ptr ip, sp;
|
|
|
766 G* gp;
|
|
|
767 struct scanstate* state = (struct scanstate*) arg;
|
|
|
768 void *gcw;
|
|
|
769
|
|
|
770 gp = runtime_g ();
|
|
|
771 gcw = state->gcw;
|
|
|
772
|
|
|
773 switch (findstackmaps (context, &ip, &sp, &stackmap))
|
|
|
774 {
|
|
|
775 case NOTFOUND_OK:
|
|
|
776 // Not a Go function. Skip this frame.
|
|
|
777 return _URC_NO_REASON;
|
|
|
778 case NOTFOUND_BAD:
|
|
|
779 {
|
|
|
780 // No stack map found.
|
|
|
781 // If we're scanning from the signal stack, the goroutine
|
|
|
782 // may be not stopped at a safepoint. Allow this case.
|
|
|
783 if (gp != gp->m->gsignal)
|
|
|
784 {
|
|
|
785 // TODO: print gp, pc, sp
|
|
|
786 runtime_throw ("no stack map");
|
|
|
787 }
|
|
|
788 return STOP_UNWINDING;
|
|
|
789 }
|
|
|
790 case FOUND:
|
|
|
791 break;
|
|
|
792 default:
|
|
|
793 abort ();
|
|
|
794 }
|
|
|
795
|
|
|
796 state->lastsp = sp;
|
|
|
797 runtime_scanstackblockwithmap (ip, sp, (uintptr)(stackmap->len) * sizeof(uintptr), stackmap->data, gcw);
|
|
|
798
|
|
|
799 return _URC_NO_REASON;
|
|
|
800 }
|
|
|
801
|
|
|
802 // Scan the stack with stack maps. Return whether the scan
|
|
|
803 // succeeded.
|
|
|
804 bool
|
|
|
805 scanstackwithmap (void *gcw)
|
|
|
806 {
|
|
|
807 _Unwind_Reason_Code code;
|
|
|
808 bool ret;
|
|
|
809 struct scanstate state;
|
|
|
810 G* gp;
|
|
|
811 G* curg;
|
|
|
812
|
|
|
813 state.gcw = gcw;
|
|
|
814 state.lastsp = 0;
|
|
|
815 gp = runtime_g ();
|
|
|
816 curg = gp->m->curg;
|
|
|
817
|
|
|
818 runtime_xadd (&__go_runtime_in_callers, 1);
|
|
|
819 code = _Unwind_Backtrace (scanstackwithmap_callback, (void*)&state);
|
|
|
820 runtime_xadd (&__go_runtime_in_callers, -1);
|
|
|
821 ret = (code == _URC_END_OF_STACK);
|
|
|
822 if (ret && gp == gp->m->gsignal)
|
|
|
823 {
|
|
|
824 // For signal-triggered scan, the unwinder may not be able to unwind
|
|
|
825 // the whole stack while it still reports _URC_END_OF_STACK (e.g.
|
|
|
826 // signal is delivered in vdso). Check that we actually reached the
|
|
|
827 // the end of the stack, that is, the SP on entry.
|
|
|
828 if (state.lastsp != curg->entrysp)
|
|
|
829 ret = false;
|
|
|
830 }
|
|
|
831 return ret;
|
|
|
832 }
|
|
|
833
|
|
|
834 // Returns whether stack map is enabled.
|
|
|
835 bool
|
|
|
836 usestackmaps ()
|
|
|
837 {
|
|
|
838 return runtime_usestackmaps;
|
|
|
839 }
|
|
|
840
|
|
|
841 // Callback function to probe if a stack frame has stack maps.
|
|
|
842 static _Unwind_Reason_Code
|
|
|
843 probestackmaps_callback (struct _Unwind_Context *context,
|
|
|
844 void *arg __attribute__ ((unused)))
|
|
|
845 {
|
|
|
846 switch (findstackmaps (context, NULL, NULL, NULL))
|
|
|
847 {
|
|
|
848 case NOTFOUND_OK:
|
|
|
849 case NOTFOUND_BAD:
|
|
|
850 return _URC_NO_REASON;
|
|
|
851 case FOUND:
|
|
|
852 break;
|
|
|
853 default:
|
|
|
854 abort ();
|
|
|
855 }
|
|
|
856
|
|
|
857 // Found a stack map. No need to keep unwinding.
|
|
|
858 runtime_usestackmaps = true;
|
|
|
859 return STOP_UNWINDING;
|
|
|
860 }
|
|
|
861
|
|
|
862 // Try to find a stack map, store the result in global variable runtime_usestackmaps.
|
|
|
863 // Called in start-up time from Go code, so there is a Go frame on the stack.
|
|
|
864 bool
|
|
|
865 probestackmaps ()
|
|
|
866 {
|
|
|
867 runtime_usestackmaps = false;
|
|
|
868 _Unwind_Backtrace (probestackmaps_callback, NULL);
|
|
|
869 return runtime_usestackmaps;
|
|
|
870 }
|
