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/*
* FreeRTOS Kernel V10.2.1
* Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/* Including FreeRTOSConfig.h here will cause build errors if the header file
contains code not understood by the assembler - for example the 'extern' keyword.
To avoid errors place any such code inside a #ifdef __ICCARM__/#endif block so
the code is included in C files but excluded by the preprocessor in assembly
files (__ICCARM__ is defined by the IAR C compiler but not by the IAR assembler. */
#include "FreeRTOSConfig.h"
EXTERN pxCurrentTCB
EXTERN vTaskSwitchContext
EXTERN vPortSVCHandler_C
PUBLIC xIsPrivileged
PUBLIC vResetPrivilege
PUBLIC vRestoreContextOfFirstTask
PUBLIC vRaisePrivilege
PUBLIC vStartFirstTask
PUBLIC ulSetInterruptMask
PUBLIC vClearInterruptMask
PUBLIC PendSV_Handler
PUBLIC SVC_Handler
/*-----------------------------------------------------------*/
/*---------------- Unprivileged Functions -------------------*/
/*-----------------------------------------------------------*/
SECTION .text:CODE:NOROOT(2)
THUMB
/*-----------------------------------------------------------*/
xIsPrivileged:
mrs r0, control /* r0 = CONTROL. */
tst r0, #1 /* Perform r0 & 1 (bitwise AND) and update the conditions flag. */
ite ne
movne r0, #0 /* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
moveq r0, #1 /* CONTROL[0]==0. Return true to indicate that the processor is not privileged. */
bx lr /* Return. */
/*-----------------------------------------------------------*/
vResetPrivilege:
mrs r0, control /* r0 = CONTROL. */
orr r0, r0, #1 /* r0 = r0 | 1. */
msr control, r0 /* CONTROL = r0. */
bx lr /* Return to the caller. */
/*-----------------------------------------------------------*/
/*----------------- Privileged Functions --------------------*/
/*-----------------------------------------------------------*/
SECTION privileged_functions:CODE:NOROOT(2)
THUMB
/*-----------------------------------------------------------*/
vRestoreContextOfFirstTask:
ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r1, [r2] /* Read pxCurrentTCB. */
ldr r0, [r1] /* Read top of stack from TCB - The first item in pxCurrentTCB is the task top of stack. */
#if ( configENABLE_MPU == 1 )
dmb /* Complete outstanding transfers before disabling MPU. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
bic r4, r4, #1 /* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
str r4, [r2] /* Disable MPU. */
adds r1, #4 /* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
ldr r3, [r1] /* r3 = *r1 i.e. r3 = MAIR0. */
ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
str r3, [r2] /* Program MAIR0. */
ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
movs r3, #4 /* r3 = 4. */
str r3, [r2] /* Program RNR = 4. */
adds r1, #4 /* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
ldr r2, =0xe000ed9c /* r2 = 0xe000ed9c [Location of RBAR]. */
ldmia r1!, {r4-r11} /* Read 4 sets of RBAR/RLAR registers from TCB. */
stmia r2!, {r4-r11} /* Write 4 set of RBAR/RLAR registers using alias registers. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
orr r4, r4, #1 /* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
str r4, [r2] /* Enable MPU. */
dsb /* Force memory writes before continuing. */
#endif /* configENABLE_MPU */
#if ( configENABLE_MPU == 1 )
ldm r0!, {r1-r3} /* Read from stack - r1 = PSPLIM, r2 = CONTROL and r3 = EXC_RETURN. */
msr psplim, r1 /* Set this task's PSPLIM value. */
msr control, r2 /* Set this task's CONTROL value. */
adds r0, #32 /* Discard everything up to r0. */
msr psp, r0 /* This is now the new top of stack to use in the task. */
isb
bx r3 /* Finally, branch to EXC_RETURN. */
#else /* configENABLE_MPU */
ldm r0!, {r1-r2} /* Read from stack - r1 = PSPLIM and r2 = EXC_RETURN. */
msr psplim, r1 /* Set this task's PSPLIM value. */
movs r1, #2 /* r1 = 2. */
msr CONTROL, r1 /* Switch to use PSP in the thread mode. */
adds r0, #32 /* Discard everything up to r0. */
msr psp, r0 /* This is now the new top of stack to use in the task. */
isb
bx r2 /* Finally, branch to EXC_RETURN. */
#endif /* configENABLE_MPU */
/*-----------------------------------------------------------*/
vRaisePrivilege:
mrs r0, control /* Read the CONTROL register. */
bic r0, r0, #1 /* Clear the bit 0. */
msr control, r0 /* Write back the new CONTROL value. */
bx lr /* Return to the caller. */
/*-----------------------------------------------------------*/
vStartFirstTask:
ldr r0, =0xe000ed08 /* Use the NVIC offset register to locate the stack. */
ldr r0, [r0] /* Read the VTOR register which gives the address of vector table. */
ldr r0, [r0] /* The first entry in vector table is stack pointer. */
msr msp, r0 /* Set the MSP back to the start of the stack. */
cpsie i /* Globally enable interrupts. */
cpsie f
dsb
isb
svc 2 /* System call to start the first task. portSVC_START_SCHEDULER = 2. */
/*-----------------------------------------------------------*/
ulSetInterruptMask:
mrs r0, basepri /* r0 = basepri. Return original basepri value. */
mov r1, #configMAX_SYSCALL_INTERRUPT_PRIORITY
msr basepri, r1 /* Disable interrupts upto configMAX_SYSCALL_INTERRUPT_PRIORITY. */
dsb
isb
bx lr /* Return. */
/*-----------------------------------------------------------*/
vClearInterruptMask:
msr basepri, r0 /* basepri = ulMask. */
dsb
isb
bx lr /* Return. */
/*-----------------------------------------------------------*/
PendSV_Handler:
mrs r0, psp /* Read PSP in r0. */
#if ( configENABLE_FPU == 1 )
tst lr, #0x10 /* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
it eq
vstmdbeq r0!, {s16-s31} /* Store the FPU registers which are not saved automatically. */
#endif /* configENABLE_FPU */
#if ( configENABLE_MPU == 1 )
mrs r1, psplim /* r1 = PSPLIM. */
mrs r2, control /* r2 = CONTROL. */
mov r3, lr /* r3 = LR/EXC_RETURN. */
stmdb r0!, {r1-r11} /* Store on the stack - PSPLIM, CONTROL, LR and registers that are not automatically saved. */
#else /* configENABLE_MPU */
mrs r2, psplim /* r2 = PSPLIM. */
mov r3, lr /* r3 = LR/EXC_RETURN. */
stmdb r0!, {r2-r11} /* Store on the stack - PSPLIM, LR and registers that are not automatically. */
#endif /* configENABLE_MPU */
ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r1, [r2] /* Read pxCurrentTCB. */
str r0, [r1] /* Save the new top of stack in TCB. */
mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
msr basepri, r0 /* Disable interrupts upto configMAX_SYSCALL_INTERRUPT_PRIORITY. */
dsb
isb
bl vTaskSwitchContext
mov r0, #0 /* r0 = 0. */
msr basepri, r0 /* Enable interrupts. */
ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r1, [r2] /* Read pxCurrentTCB. */
ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. r0 now points to the top of stack. */
#if ( configENABLE_MPU == 1 )
dmb /* Complete outstanding transfers before disabling MPU. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
bic r4, r4, #1 /* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
str r4, [r2] /* Disable MPU. */
adds r1, #4 /* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
ldr r3, [r1] /* r3 = *r1 i.e. r3 = MAIR0. */
ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
str r3, [r2] /* Program MAIR0. */
ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
movs r3, #4 /* r3 = 4. */
str r3, [r2] /* Program RNR = 4. */
adds r1, #4 /* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
ldr r2, =0xe000ed9c /* r2 = 0xe000ed9c [Location of RBAR]. */
ldmia r1!, {r4-r11} /* Read 4 sets of RBAR/RLAR registers from TCB. */
stmia r2!, {r4-r11} /* Write 4 set of RBAR/RLAR registers using alias registers. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
orr r4, r4, #1 /* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
str r4, [r2] /* Enable MPU. */
dsb /* Force memory writes before continuing. */
#endif /* configENABLE_MPU */
#if ( configENABLE_MPU == 1 )
ldmia r0!, {r1-r11} /* Read from stack - r1 = PSPLIM, r2 = CONTROL, r3 = LR and r4-r11 restored. */
#else /* configENABLE_MPU */
ldmia r0!, {r2-r11} /* Read from stack - r2 = PSPLIM, r3 = LR and r4-r11 restored. */
#endif /* configENABLE_MPU */
#if ( configENABLE_FPU == 1 )
tst r3, #0x10 /* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
it eq
vldmiaeq r0!, {s16-s31} /* Restore the FPU registers which are not restored automatically. */
#endif /* configENABLE_FPU */
#if ( configENABLE_MPU == 1 )
msr psplim, r1 /* Restore the PSPLIM register value for the task. */
msr control, r2 /* Restore the CONTROL register value for the task. */
#else /* configENABLE_MPU */
msr psplim, r2 /* Restore the PSPLIM register value for the task. */
#endif /* configENABLE_MPU */
msr psp, r0 /* Remember the new top of stack for the task. */
bx r3
/*-----------------------------------------------------------*/
SVC_Handler:
tst lr, #4
ite eq
mrseq r0, msp
mrsne r0, psp
b vPortSVCHandler_C
/*-----------------------------------------------------------*/
END
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