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1 //low-level trap handler glue code
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2 #include "arm.h"
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3
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4 .text
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5 .code 32
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6
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7 .global trap_swi
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8 .global trap_irq
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9 .global trap_reset
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10 .global trap_und
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11 .global trap_iabort
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12 .global trap_dabort
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13 .global trap_na
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14 .global trap_fiq
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15 .global trapret
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16
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17
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18 # handle SWI, we allow nested SWI
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19 trap_swi:
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20 # build trapframe on the stack
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21 STMFD sp!, {r0-r12, r14} // save context
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22 MRS r2, spsr // copy spsr to r2
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23 STMFD r13!, {r2} // save r2(spsr) to the stack
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24 STMFD r13!, {r14} // save r14 again to have one uniform trapframe
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25 STMFD r13, {sp, lr}^ // save user mode sp and lr
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26 SUB r13, r13, #8
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27
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28 # call traps (trapframe *fp)
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29 MOV r0, r13 // copy r13_svc to r0
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30 BL swi_handler // branch to the isr_swi
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31
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32 # restore states
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33 trapret:
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34 LDMFD r13, {sp, lr}^ // restore user mode sp and lr
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35 ADD r13, r13, #8
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36 LDMFD r13!, {r14} // restore r14
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37 LDMFD r13!, {r2} // restore spsr
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38 MSR spsr_cxsf, r2
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39 LDMFD r13!,{r0-r12, pc}^ // restore context and return
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40
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41
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42 # handle IRQ, we allow nested IRQs
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43 trap_irq:
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44 # save a few registers to the irq stack to provide scratch regs.
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45 # r14 (lr_irq) contains the instruction (pc) to return to, need to
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46 # save it on the stack as r14 is banked
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47 SUB r14, r14, #4 // r14 (lr) contains the interrupted PC
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48 STMFD r13!, {r0-r2, r14} //
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49 MRS r1, spsr // save spsr_irq
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50 MOV r0, r13 // save stack stop (r13_irq)
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51 ADD r13, r13, #16 // reset the IRQ stack
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52
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53 # switch to the SVC mode
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54 MRS r2, cpsr
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55 BIC r2, r2, #MODE_MASK
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56 ORR r2, r2, #SVC_MODE
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57 MSR cpsr_cxsf, r2
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58
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59 # now, in SVC mode, sp, lr, pc (r13, r14, r15) are all banked
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60 # build the trap frame
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61 LDR r2, [r0, #12] // read the r14_irq, then save it
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62 STMFD r13!, {r2}
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63 STMFD r13!, {r3-r12} // r4-r12 are preserved (non-banked)
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64 LDMFD r0, {r3-r5} // copy r0-r2 over from irq stack
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65 STMFD r13!, {r3-r5}
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66 STMFD r13!, {r1} // save spsr
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67 STMFD r13!, {lr} // save r14_svc
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68
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69 STMFD r13, {sp, lr}^ // save user mode sp and lr
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70 SUB r13, r13, #8
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71
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72 # get the parameters, then call the handler
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73 MOV r0, r13 // points to
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74 BL irq_handler
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75
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76 # restore the previous status
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77 B trapret
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78
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79 # handle reset/undefine instruction/abort/not-assigned/fiq
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80 # these handler does not allow nested handling
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81 trap_reset:
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82 MOV r14, #0 // lr: not defined on reset
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83 STMFD r13!, {r0-r12, r14}
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84 MRS r2, spsr // copy spsr to r2
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85 STMFD r13!, {r2} // save r2(spsr) to the stack
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86 STMFD r13!, {r14} // save r14 again (it is not really correct)
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87 STMFD r13, {sp, lr}^ // save user mode sp and lr
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88 SUB r13, r13, #8
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89
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90 # call traps (trapframe *fp)
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91 MOV r0, r13 // copy r13_svc to r0
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92 BL reset_handler
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93 B .
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94
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95 trap_und:
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96 STMFD r13!, {r0-r12, r14} // lr: instruction after the undefined
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97 MRS r2, spsr // copy spsr to r2
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98 STMFD r13!, {r2} // save r2(spsr) to the stack
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99 STMFD r13!, {r14} // save r14 again (it is not really correct)
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100 STMFD r13, {sp, lr}^ // save user mode sp and lr
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101 SUB r13, r13, #8
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102
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103 # call traps (trapframe *fp)
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104 MOV r0, r13 // save trapframe as the first parameter
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105 BL und_handler
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106 B .
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107
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108 trap_iabort:
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109 SUB r14, r14, #4 // lr: instruction causing the abort
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110 STMFD r13!, {r0-r12, r14}
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111 MRS r2, spsr // copy spsr to r2
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112 STMFD r13!, {r2} // save r2(spsr) to the stack
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113 STMFD r13!, {r14} // save r14 again (it is not really correct)
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114 STMFD r13, {sp, lr}^ // save user mode sp and lr
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115 SUB r13, r13, #8
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116
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117 # call traps (trapframe *fp)
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118 MOV r0, r13 // save trapframe as the first parameter
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119 BL iabort_handler
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120 B .
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121
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122 trap_dabort:
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123 SUB r14, r14, #8 // lr: instruction causing the abort
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124 STMFD r13!, {r0-r12, r14}
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125 MRS r2, spsr // copy spsr to r2
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126 STMFD r13!, {r2} // save r2(spsr) to the stack
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127 STMFD r13!, {r14} // save r14 again (it is not really correct)
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128 STMFD r13, {sp, lr}^ // save user mode sp and lr
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129 SUB r13, r13, #8
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130
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131 # call traps (trapframe *fp)
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132 MOV r0, r13 // save trapframe as the first parameter
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133 BL dabort_handler
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134 MOV r0, #2 // #SYS_exit
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135 SWI 0x00
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136 B exit
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137 #B . // trapret
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138
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139 trap_na:
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140 STMFD r13!, {r0-r12, r14} // should never happen, hardware error
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141 MRS r2, spsr // copy spsr to r2
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142 STMFD r13!, {r2} // save r2(spsr) to the stack
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143 STMFD r13!, {r14} // save r14 again (it is not really correct)
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144 STMFD r13, {sp, lr}^ // save user mode sp and lr
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145 SUB r13, r13, #8
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146
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147 # call traps (trapframe *fp)
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148 MOV r0, r13 // save trapframe as the first parameter
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149 BL na_handler
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150 B .
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151
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152 trap_fiq:
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153 SUB r14, r14, #4 // lr: return address after the fiq handler
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154 STMFD r13!, {r0-r12, r14}
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155 MRS r2, spsr // copy spsr to r2
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156 STMFD r13!, {r2} // save r2(spsr) to the stack
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157 STMFD r13!, {r14} // save r14 again (it is not really correct)
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158 STMFD r13, {sp, lr}^ // save user mode sp and lr
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159 SUB r13, r13, #8
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160
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161 # call traps (trapframe *fp)
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162 MOV r0, r13 // save trapframe as the first parameter
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163 BL fiq_handler
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164 B .
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165
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