2 * FreeRTOS Kernel V10.2.1
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3 * Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 EXTERN vTaskSwitchContext
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30 EXTERN vPortSVCHandler_C
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32 PUBLIC xIsPrivileged
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33 PUBLIC vResetPrivilege
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34 PUBLIC vRestoreContextOfFirstTask
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35 PUBLIC vRaisePrivilege
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36 PUBLIC vStartFirstTask
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37 PUBLIC ulSetInterruptMaskFromISR
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38 PUBLIC vClearInterruptMaskFromISR
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39 PUBLIC PendSV_Handler
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41 /*-----------------------------------------------------------*/
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43 /*---------------- Unprivileged Functions -------------------*/
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45 /*-----------------------------------------------------------*/
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47 SECTION .text:CODE:NOROOT(2)
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49 /*-----------------------------------------------------------*/
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52 mrs r0, control /* r0 = CONTROL. */
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53 tst r0, #1 /* Perform r0 & 1 (bitwise AND) and update the conditions flag. */
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55 movne r0, #0 /* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
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56 moveq r0, #1 /* CONTROL[0]==0. Return true to indicate that the processor is not privileged. */
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58 /*-----------------------------------------------------------*/
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61 mrs r0, control /* r0 = CONTROL. */
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62 orr r0, r0, #1 /* r0 = r0 | 1. */
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63 msr control, r0 /* CONTROL = r0. */
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64 bx lr /* Return to the caller. */
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65 /*-----------------------------------------------------------*/
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67 /*----------------- Privileged Functions --------------------*/
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69 /*-----------------------------------------------------------*/
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71 SECTION privileged_functions:CODE:NOROOT(2)
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73 /*-----------------------------------------------------------*/
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75 vRestoreContextOfFirstTask:
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76 ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
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77 ldr r1, [r2] /* Read pxCurrentTCB. */
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78 ldr r0, [r1] /* Read top of stack from TCB - The first item in pxCurrentTCB is the task top of stack. */
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80 #if ( configENABLE_MPU == 1 )
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81 dmb /* Complete outstanding transfers before disabling MPU. */
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82 ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
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83 ldr r4, [r2] /* Read the value of MPU_CTRL. */
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84 bic r4, r4, #1 /* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
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85 str r4, [r2] /* Disable MPU. */
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87 adds r1, #4 /* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
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88 ldr r3, [r1] /* r3 = *r1 i.e. r3 = MAIR0. */
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89 ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
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90 str r3, [r2] /* Program MAIR0. */
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91 ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
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92 movs r3, #4 /* r3 = 4. */
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93 str r3, [r2] /* Program RNR = 4. */
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94 adds r1, #4 /* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
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95 ldr r2, =0xe000ed9c /* r2 = 0xe000ed9c [Location of RBAR]. */
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96 ldmia r1!, {r4-r11} /* Read 4 sets of RBAR/RLAR registers from TCB. */
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97 stmia r2!, {r4-r11} /* Write 4 set of RBAR/RLAR registers using alias registers. */
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99 ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
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100 ldr r4, [r2] /* Read the value of MPU_CTRL. */
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101 orr r4, r4, #1 /* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
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102 str r4, [r2] /* Enable MPU. */
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103 dsb /* Force memory writes before continuing. */
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104 #endif /* configENABLE_MPU */
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106 #if ( configENABLE_MPU == 1 )
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107 ldm r0!, {r1-r3} /* Read from stack - r1 = PSPLIM, r2 = CONTROL and r3 = EXC_RETURN. */
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108 msr psplim, r1 /* Set this task's PSPLIM value. */
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109 msr control, r2 /* Set this task's CONTROL value. */
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110 adds r0, #32 /* Discard everything up to r0. */
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111 msr psp, r0 /* This is now the new top of stack to use in the task. */
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113 bx r3 /* Finally, branch to EXC_RETURN. */
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114 #else /* configENABLE_MPU */
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115 ldm r0!, {r1-r2} /* Read from stack - r1 = PSPLIM and r2 = EXC_RETURN. */
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116 msr psplim, r1 /* Set this task's PSPLIM value. */
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117 movs r1, #2 /* r1 = 2. */
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118 msr CONTROL, r1 /* Switch to use PSP in the thread mode. */
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119 adds r0, #32 /* Discard everything up to r0. */
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120 msr psp, r0 /* This is now the new top of stack to use in the task. */
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122 bx r2 /* Finally, branch to EXC_RETURN. */
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123 #endif /* configENABLE_MPU */
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124 /*-----------------------------------------------------------*/
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127 mrs r0, control /* Read the CONTROL register. */
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128 bic r0, r0, #1 /* Clear the bit 0. */
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129 msr control, r0 /* Write back the new CONTROL value. */
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130 bx lr /* Return to the caller. */
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131 /*-----------------------------------------------------------*/
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134 ldr r0, =0xe000ed08 /* Use the NVIC offset register to locate the stack. */
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135 ldr r0, [r0] /* Read the VTOR register which gives the address of vector table. */
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136 ldr r0, [r0] /* The first entry in vector table is stack pointer. */
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137 msr msp, r0 /* Set the MSP back to the start of the stack. */
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138 cpsie i /* Globally enable interrupts. */
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142 svc 2 /* System call to start the first task. portSVC_START_SCHEDULER = 2. */
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143 /*-----------------------------------------------------------*/
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145 ulSetInterruptMaskFromISR:
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149 /*-----------------------------------------------------------*/
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151 vClearInterruptMaskFromISR:
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154 /*-----------------------------------------------------------*/
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157 mrs r0, psp /* Read PSP in r0. */
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158 #if ( configENABLE_FPU == 1 )
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159 tst lr, #0x10 /* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
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161 vstmdbeq r0!, {s16-s31} /* Store the FPU registers which are not saved automatically. */
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162 #endif /* configENABLE_FPU */
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163 #if ( configENABLE_MPU == 1 )
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164 mrs r1, psplim /* r1 = PSPLIM. */
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165 mrs r2, control /* r2 = CONTROL. */
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166 mov r3, lr /* r3 = LR/EXC_RETURN. */
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167 stmdb r0!, {r1-r11} /* Store on the stack - PSPLIM, CONTROL, LR and registers that are not automatically saved. */
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168 #else /* configENABLE_MPU */
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169 mrs r2, psplim /* r2 = PSPLIM. */
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170 mov r3, lr /* r3 = LR/EXC_RETURN. */
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171 stmdb r0!, {r2-r11} /* Store on the stack - PSPLIM, LR and registers that are not automatically. */
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172 #endif /* configENABLE_MPU */
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174 ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
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175 ldr r1, [r2] /* Read pxCurrentTCB. */
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176 str r0, [r1] /* Save the new top of stack in TCB. */
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179 bl vTaskSwitchContext
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182 ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
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183 ldr r1, [r2] /* Read pxCurrentTCB. */
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184 ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. r0 now points to the top of stack. */
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186 #if ( configENABLE_MPU == 1 )
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187 dmb /* Complete outstanding transfers before disabling MPU. */
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188 ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
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189 ldr r4, [r2] /* Read the value of MPU_CTRL. */
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190 bic r4, r4, #1 /* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
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191 str r4, [r2] /* Disable MPU. */
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193 adds r1, #4 /* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
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194 ldr r3, [r1] /* r3 = *r1 i.e. r3 = MAIR0. */
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195 ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
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196 str r3, [r2] /* Program MAIR0. */
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197 ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
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198 movs r3, #4 /* r3 = 4. */
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199 str r3, [r2] /* Program RNR = 4. */
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200 adds r1, #4 /* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
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201 ldr r2, =0xe000ed9c /* r2 = 0xe000ed9c [Location of RBAR]. */
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202 ldmia r1!, {r4-r11} /* Read 4 sets of RBAR/RLAR registers from TCB. */
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203 stmia r2!, {r4-r11} /* Write 4 set of RBAR/RLAR registers using alias registers. */
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205 ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
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206 ldr r4, [r2] /* Read the value of MPU_CTRL. */
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207 orr r4, r4, #1 /* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
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208 str r4, [r2] /* Enable MPU. */
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209 dsb /* Force memory writes before continuing. */
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210 #endif /* configENABLE_MPU */
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212 #if ( configENABLE_MPU == 1 )
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213 ldmia r0!, {r1-r11} /* Read from stack - r1 = PSPLIM, r2 = CONTROL, r3 = LR and r4-r11 restored. */
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214 #else /* configENABLE_MPU */
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215 ldmia r0!, {r2-r11} /* Read from stack - r2 = PSPLIM, r3 = LR and r4-r11 restored. */
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216 #endif /* configENABLE_MPU */
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218 #if ( configENABLE_FPU == 1 )
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219 tst r3, #0x10 /* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
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221 vldmiaeq r0!, {s16-s31} /* Restore the FPU registers which are not restored automatically. */
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222 #endif /* configENABLE_FPU */
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224 #if ( configENABLE_MPU == 1 )
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225 msr psplim, r1 /* Restore the PSPLIM register value for the task. */
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226 msr control, r2 /* Restore the CONTROL register value for the task. */
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227 #else /* configENABLE_MPU */
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228 msr psplim, r2 /* Restore the PSPLIM register value for the task. */
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229 #endif /* configENABLE_MPU */
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230 msr psp, r0 /* Remember the new top of stack for the task. */
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232 /*-----------------------------------------------------------*/
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239 b vPortSVCHandler_C
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240 /*-----------------------------------------------------------*/
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