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1 ##============================================================================= |
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2 ## |
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3 ## context.S |
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4 ## |
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5 ## i386 context switch code |
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6 ## |
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7 ##============================================================================= |
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8 #####COPYRIGHTBEGIN#### |
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9 # |
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10 # ------------------------------------------- |
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11 # The contents of this file are subject to the Cygnus eCos Public License |
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12 # Version 1.0 (the "License"); you may not use this file except in |
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13 # compliance with the License. You may obtain a copy of the License at |
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14 # http://sourceware.cygnus.com/ecos |
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15 # |
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16 # Software distributed under the License is distributed on an "AS IS" |
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17 # basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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18 # License for the specific language governing rights and limitations under |
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19 # the License. |
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20 # |
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21 # The Original Code is eCos - Embedded Cygnus Operating System, released |
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22 # September 30, 1998. |
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23 # |
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24 # The Initial Developer of the Original Code is Cygnus. Portions created |
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25 # by Cygnus are Copyright (C) 1998,1999 Cygnus Solutions. All Rights Reserved. |
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26 # ------------------------------------------- |
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27 # |
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28 #####COPYRIGHTEND#### |
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29 ##============================================================================= |
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30 #######DESCRIPTIONBEGIN#### |
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31 ## |
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32 ## Author(s): jskov |
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33 ## Contributors:jskov |
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34 ## Date: 1999-01-20 |
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35 ## Purpose: i386 context switch code |
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36 ## Description: This file contains implementations of the thread context |
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37 ## switch routines. It also contains the longjmp() and setjmp() |
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38 ## routines. |
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39 ## Based on PowerPC context.S, using data from SYSV ABI4, i386 |
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40 ## supplement (page 37-38) |
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41 ## http://www.sco.com/products/layered/develop/devspecs/abi386-4.pdf |
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42 ## |
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43 ######DESCRIPTIONEND#### |
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44 ## |
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45 ##============================================================================= |
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46 |
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47 #include <pkgconf/hal.h> |
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48 |
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49 #include "cyg/hal/i386.inc" |
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50 |
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51 #------------------------------------------------------------------------------ |
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52 # function declaration macro |
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53 |
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54 #define FUNC_START(name) \ |
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55 .globl name; \ |
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56 name: |
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57 |
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58 #------------------------------------------------------------------------------ |
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59 # hal_thread_switch_context |
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60 # Switch thread contexts |
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61 # : 0(%esp) : return address |
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62 # : 4(%esp) : address of sp of next thread to execute |
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63 # : 8(%esp) : address of sp save location of current thread |
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64 # |
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65 # %eax, %ecx, and %edx are ours to abuse. |
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66 |
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67 FUNC_START(hal_thread_switch_context) |
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68 movl 4(%esp),%eax # next context ptr |
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69 movl 8(%esp),%edx # this context ptr |
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70 |
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71 # Make room on the stack for the context |
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72 movl %esp,%ecx # keep original SP |
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73 sub $i386reg_context_size,%esp |
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74 |
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75 # Save next context ptr in this context. Necessary because |
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76 # hal_thread_load_context expects to find the ptr on the stack, |
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77 # not in a register as on PPC. |
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78 movl %eax,i386reg_next_context(%esp) |
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79 |
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80 # Save registers |
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81 movl %ecx,i386reg_esp(%esp) # original esp |
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82 movl %ebp,i386reg_ebp(%esp) |
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83 movl %ebx,i386reg_ebx(%esp) |
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84 movl %esi,i386reg_esi(%esp) |
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85 movl %edi,i386reg_edi(%esp) |
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86 |
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87 # Store the context ptr |
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88 movl %esp,(%edx) |
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89 |
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90 # Now fall through to hal_thread_load_context |
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91 |
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92 |
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93 #------------------------------------------------------------------------------ |
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94 # hal_thread_load_context |
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95 # Load thread context |
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96 # : 4(%esp) = i386reg_next_context(%esp) = address of sp of thread to execute |
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97 # Note that this function is also the second half of hal_thread_switch_context |
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98 # and is simply dropped into from it. |
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99 # |
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100 # %eax, %ecx, and %edx are ours to abuse. |
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101 |
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102 FUNC_START(hal_thread_load_context) |
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103 movl i386reg_next_context(%esp),%eax # get new context ptr |
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104 movl (%eax),%eax |
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105 |
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106 # Restore registers |
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107 movl i386reg_ebp(%eax),%ebp |
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108 movl i386reg_ebx(%eax),%ebx |
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109 movl i386reg_esi(%eax),%esi |
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110 movl i386reg_edi(%eax),%edi |
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111 movl i386reg_esp(%eax),%esp |
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112 |
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113 ret |
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114 |
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115 |
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116 #------------------------------------------------------------------------------ |
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117 # HAL longjmp, setjmp implementations |
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118 # hal_setjmp saves only to callee save registers ebp, ebx, esi, edi and |
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119 # and esp+pc into buffer supplied in 4(esp) |
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120 # Note: These definitions are repeated in hal_arch.h. If changes are required |
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121 # remember to update both sets. |
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122 |
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123 #define CYGARC_JMP_BUF_SP 0 |
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124 #define CYGARC_JMP_BUF_EBP 1 |
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125 #define CYGARC_JMP_BUF_EBX 2 |
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126 #define CYGARC_JMP_BUF_ESI 3 |
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127 #define CYGARC_JMP_BUF_EDI 4 |
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128 #define CYGARC_JMP_BUF_PC 5 |
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129 |
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130 #define CYGARC_JMP_BUF_SIZE 6 |
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131 |
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132 FUNC_START(hal_setjmp) |
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133 # Get jmpbuf pointer |
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134 movl 4(%esp),%eax |
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135 |
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136 # Save regular registers |
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137 movl %ebp,CYGARC_JMP_BUF_EBP*4(%eax) |
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138 movl %ebx,CYGARC_JMP_BUF_EBX*4(%eax) |
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139 movl %esi,CYGARC_JMP_BUF_ESI*4(%eax) |
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140 movl %edi,CYGARC_JMP_BUF_EDI*4(%eax) |
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141 |
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142 # Stack and PC |
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143 movl %esp,CYGARC_JMP_BUF_SP*4(%eax) |
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144 movl 0(%esp),%ebx |
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145 movl %ebx,CYGARC_JMP_BUF_PC*4(%eax) |
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146 |
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147 # Return 0 |
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148 xor %eax,%eax |
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149 ret |
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150 |
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151 |
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152 # hal_longjmp loads state from 4(esp) and returns to PC stored in state |
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153 |
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154 FUNC_START(hal_longjmp) |
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155 # Get return value |
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156 movl 8(%esp),%eax |
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157 |
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158 # Get jmpbuf pointer |
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159 movl 4(%esp),%ecx |
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160 |
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161 # Restore regular registers |
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162 movl CYGARC_JMP_BUF_EBP*4(%ecx),%ebp |
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163 movl CYGARC_JMP_BUF_EBX*4(%ecx),%ebx |
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164 movl CYGARC_JMP_BUF_ESI*4(%ecx),%esi |
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165 movl CYGARC_JMP_BUF_EDI*4(%ecx),%edi |
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166 |
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167 # Restore stack pointer |
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168 movl CYGARC_JMP_BUF_SP*4(%ecx),%esp |
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169 |
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170 # Put return address on stack |
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171 movl CYGARC_JMP_BUF_PC*4(%ecx),%edx |
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172 movl %edx,0(%esp) |
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173 |
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174 ret |
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175 |
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176 #----------------------------------------------------------------------------- |
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177 # End of context.S |
