1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup RTEMSScoreTLS |
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5 | * |
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6 | * @brief Thread-Local Storage (TLS) |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (c) 2014 embedded brains GmbH. All rights reserved. |
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11 | * |
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12 | * embedded brains GmbH |
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13 | * Dornierstr. 4 |
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14 | * 82178 Puchheim |
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15 | * Germany |
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16 | * <rtems@embedded-brains.de> |
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17 | * |
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18 | * The license and distribution terms for this file may be |
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19 | * found in the file LICENSE in this distribution or at |
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20 | * http://www.rtems.org/license/LICENSE. |
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21 | */ |
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22 | |
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23 | #ifndef _RTEMS_SCORE_TLS_H |
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24 | #define _RTEMS_SCORE_TLS_H |
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25 | |
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26 | #include <rtems/score/cpu.h> |
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27 | |
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28 | #include <string.h> |
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29 | |
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30 | #ifdef __cplusplus |
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31 | extern "C" { |
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32 | #endif /* __cplusplus */ |
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33 | |
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34 | /** |
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35 | * @defgroup RTEMSScoreTLS Thread-Local Storage (TLS) |
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36 | * |
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37 | * @ingroup RTEMSScore |
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38 | * |
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39 | * @brief Thread-local storage (TLS) support. |
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40 | * |
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41 | * Variants I and II are according to Ulrich Drepper, "ELF Handling For |
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42 | * Thread-Local Storage". |
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43 | * |
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44 | * @{ |
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45 | */ |
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46 | |
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47 | extern char _TLS_Data_begin[]; |
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48 | |
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49 | extern char _TLS_Data_end[]; |
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50 | |
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51 | extern char _TLS_Data_size[]; |
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52 | |
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53 | extern char _TLS_BSS_begin[]; |
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54 | |
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55 | extern char _TLS_BSS_end[]; |
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56 | |
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57 | extern char _TLS_BSS_size[]; |
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58 | |
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59 | extern char _TLS_Size[]; |
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60 | |
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61 | /** |
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62 | * @brief The TLS section alignment. |
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63 | * |
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64 | * This symbol is provided by the linker command file as the maximum alignment |
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65 | * of the .tdata and .tbss sections. The linker ensures that the first TLS |
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66 | * output section is aligned to the maximum alignment of all TLS output |
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67 | * sections, see function _bfd_elf_tls_setup() in bfd/elflink.c of the GNU |
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68 | * Binutils sources. The linker command file must take into account the case |
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69 | * that the .tdata section is empty and the .tbss section is non-empty. |
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70 | */ |
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71 | extern char _TLS_Alignment[]; |
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72 | |
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73 | typedef struct { |
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74 | /* |
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75 | * FIXME: Not sure if the generation number type is correct for all |
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76 | * architectures. |
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77 | */ |
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78 | uint32_t generation_number; |
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79 | |
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80 | void *tls_blocks[1]; |
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81 | } TLS_Dynamic_thread_vector; |
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82 | |
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83 | typedef struct TLS_Thread_control_block { |
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84 | #ifdef __i386__ |
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85 | struct TLS_Thread_control_block *tcb; |
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86 | #else /* !__i386__ */ |
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87 | TLS_Dynamic_thread_vector *dtv; |
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88 | #if CPU_SIZEOF_POINTER == 4 |
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89 | uintptr_t reserved; |
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90 | #endif |
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91 | #endif /* __i386__ */ |
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92 | } TLS_Thread_control_block; |
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93 | |
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94 | typedef struct { |
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95 | uintptr_t module; |
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96 | uintptr_t offset; |
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97 | } TLS_Index; |
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98 | |
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99 | /** |
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100 | * @brief Gets the TLS size. |
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101 | * |
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102 | * @return The TLS size. |
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103 | */ |
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104 | static inline uintptr_t _TLS_Get_size( void ) |
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105 | { |
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106 | uintptr_t size; |
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107 | |
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108 | /* |
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109 | * We must be careful with using _TLS_Size here since this could lead GCC to |
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110 | * assume that this symbol is not 0 and the tests for 0 will be optimized |
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111 | * away. |
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112 | */ |
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113 | size = (uintptr_t) _TLS_Size; |
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114 | RTEMS_OBFUSCATE_VARIABLE( size ); |
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115 | return size; |
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116 | } |
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117 | |
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118 | /** |
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119 | * @brief Returns the value aligned up to the heap alignment. |
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120 | * |
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121 | * @param val The value to align. |
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122 | * |
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123 | * @return The value aligned to the heap alignment. |
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124 | */ |
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125 | static inline uintptr_t _TLS_Heap_align_up( uintptr_t val ) |
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126 | { |
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127 | uintptr_t msk = CPU_HEAP_ALIGNMENT - 1; |
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128 | |
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129 | return (val + msk) & ~msk; |
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130 | } |
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131 | |
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132 | /** |
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133 | * @brief Returns the size of the thread control block area size for this |
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134 | * alignment, or the minimum size if alignment is too small. |
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135 | * |
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136 | * @param alignment The alignment for the operation. |
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137 | * |
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138 | * @return The size of the thread control block area. |
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139 | */ |
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140 | static inline uintptr_t _TLS_Get_thread_control_block_area_size( |
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141 | uintptr_t alignment |
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142 | ) |
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143 | { |
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144 | return alignment <= sizeof(TLS_Thread_control_block) ? |
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145 | sizeof(TLS_Thread_control_block) : alignment; |
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146 | } |
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147 | |
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148 | /** |
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149 | * @brief Return the TLS area allocation size. |
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150 | * |
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151 | * @return The TLS area allocation size. |
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152 | */ |
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153 | uintptr_t _TLS_Get_allocation_size( void ); |
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154 | |
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155 | /** |
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156 | * @brief Copies TLS size bytes from the address tls_area and returns a pointer |
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157 | * to the start of the area after clearing it. |
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158 | * |
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159 | * @param tls_area The starting address of the area to clear. |
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160 | * |
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161 | * @return The pointer to the beginning of the cleared section. |
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162 | */ |
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163 | static inline void *_TLS_Copy_and_clear( void *tls_area ) |
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164 | { |
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165 | tls_area = memcpy( |
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166 | tls_area, |
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167 | _TLS_Data_begin, |
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168 | (size_t) ((uintptr_t)_TLS_Data_size) |
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169 | ); |
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170 | |
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171 | |
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172 | memset( |
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173 | (char *) tls_area + (size_t)((intptr_t) _TLS_BSS_begin) - |
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174 | (size_t)((intptr_t) _TLS_Data_begin), |
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175 | 0, |
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176 | ((size_t) (intptr_t)_TLS_BSS_size) |
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177 | ); |
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178 | |
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179 | return tls_area; |
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180 | } |
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181 | |
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182 | /** |
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183 | * @brief Initializes the dynamic thread vector. |
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184 | * |
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185 | * @param tls_block The tls block for @a dtv. |
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186 | * @param tcb The thread control block for @a dtv. |
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187 | * @param[out] dtv The dynamic thread vector to initialize. |
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188 | * |
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189 | * @return Pointer to an area that was copied and cleared from tls_block |
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190 | * onwards (@see _TLS_Copy_and_clear). |
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191 | */ |
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192 | static inline void *_TLS_Initialize( |
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193 | void *tls_block, |
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194 | TLS_Thread_control_block *tcb, |
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195 | TLS_Dynamic_thread_vector *dtv |
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196 | ) |
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197 | { |
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198 | #ifdef __i386__ |
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199 | (void) dtv; |
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200 | tcb->tcb = tcb; |
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201 | #else |
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202 | tcb->dtv = dtv; |
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203 | dtv->generation_number = 1; |
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204 | dtv->tls_blocks[0] = tls_block; |
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205 | #endif |
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206 | |
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207 | return _TLS_Copy_and_clear( tls_block ); |
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208 | } |
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209 | |
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210 | /** |
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211 | * @brief Initializes a dynamic thread vector beginning at the given starting |
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212 | * address. |
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213 | * |
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214 | * Use Variant I, TLS offsets emitted by linker takes the TCB into account. |
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215 | * |
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216 | * @param tls_area The tls area for the initialization. |
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217 | * |
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218 | * @return Pointer to an area that was copied and cleared from tls_block |
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219 | * onwards (@see _TLS_Copy_and_clear). |
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220 | */ |
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221 | static inline void *_TLS_TCB_at_area_begin_initialize( void *tls_area ) |
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222 | { |
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223 | void *tls_block = (char *) tls_area |
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224 | + _TLS_Get_thread_control_block_area_size( (uintptr_t) _TLS_Alignment ); |
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225 | TLS_Thread_control_block *tcb = (TLS_Thread_control_block*) tls_area; |
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226 | uintptr_t aligned_size = _TLS_Heap_align_up( (uintptr_t) _TLS_Size ); |
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227 | TLS_Dynamic_thread_vector *dtv = (TLS_Dynamic_thread_vector *) |
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228 | ((char *) tls_block + aligned_size); |
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229 | |
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230 | return _TLS_Initialize( tls_block, tcb, dtv ); |
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231 | } |
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232 | |
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233 | /** |
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234 | * @brief Initializes a dynamic thread vector with the area before a given |
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235 | * starting address as thread control block. |
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236 | * |
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237 | * Use Variant I, TLS offsets emitted by linker neglects the TCB. |
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238 | * |
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239 | * @param tls_area The tls area for the initialization. |
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240 | * |
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241 | * @return Pointer to an area that was copied and cleared from tls_block |
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242 | * onwards (@see _TLS_Copy_and_clear). |
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243 | */ |
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244 | static inline void *_TLS_TCB_before_TLS_block_initialize( void *tls_area ) |
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245 | { |
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246 | void *tls_block = (char *) tls_area |
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247 | + _TLS_Get_thread_control_block_area_size( (uintptr_t) _TLS_Alignment ); |
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248 | TLS_Thread_control_block *tcb = (TLS_Thread_control_block *) |
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249 | ((char *) tls_block - sizeof(*tcb)); |
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250 | uintptr_t aligned_size = _TLS_Heap_align_up( (uintptr_t) _TLS_Size ); |
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251 | TLS_Dynamic_thread_vector *dtv = (TLS_Dynamic_thread_vector *) |
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252 | ((char *) tls_block + aligned_size); |
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253 | |
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254 | return _TLS_Initialize( tls_block, tcb, dtv ); |
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255 | } |
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256 | |
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257 | /** |
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258 | * @brief Initializes a dynamic thread vector with the area after a given |
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259 | * starting address as thread control block. |
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260 | * |
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261 | * Use Variant II |
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262 | * |
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263 | * @param tls_area The tls area for the initialization. |
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264 | * |
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265 | * @return Pointer to an area that was copied and cleared from tls_block |
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266 | * onwards (@see _TLS_Copy_and_clear). |
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267 | */ |
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268 | static inline void *_TLS_TCB_after_TLS_block_initialize( void *tls_area ) |
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269 | { |
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270 | uintptr_t size = (uintptr_t) _TLS_Size; |
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271 | uintptr_t tls_align = (uintptr_t) _TLS_Alignment; |
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272 | uintptr_t tls_mask = tls_align - 1; |
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273 | uintptr_t heap_align = _TLS_Heap_align_up( tls_align ); |
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274 | uintptr_t heap_mask = heap_align - 1; |
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275 | TLS_Thread_control_block *tcb = (TLS_Thread_control_block *) |
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276 | ((char *) tls_area + ((size + heap_mask) & ~heap_mask)); |
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277 | void *tls_block = (char *) tcb - ((size + tls_mask) & ~tls_mask); |
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278 | TLS_Dynamic_thread_vector *dtv = (TLS_Dynamic_thread_vector *) |
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279 | ((char *) tcb + sizeof(*tcb)); |
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280 | |
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281 | _TLS_Initialize( tls_block, tcb, dtv ); |
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282 | |
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283 | return tcb; |
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284 | } |
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285 | |
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286 | /** @} */ |
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287 | |
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288 | #ifdef __cplusplus |
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289 | } |
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290 | #endif /* __cplusplus */ |
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291 | |
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292 | #endif /* _RTEMS_SCORE_TLS_H */ |
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