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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!
*/
EXTERN pxCurrentTCB
EXTERN xSecureContext
EXTERN vTaskSwitchContext
EXTERN vPortSVCHandler_C
EXTERN SecureContext_SaveContext
EXTERN SecureContext_LoadContext
PUBLIC xIsPrivileged
PUBLIC vResetPrivilege
PUBLIC vPortAllocateSecureContext
PUBLIC vRestoreContextOfFirstTask
PUBLIC vRaisePrivilege
PUBLIC vStartFirstTask
PUBLIC ulSetInterruptMaskFromISR
PUBLIC vClearInterruptMaskFromISR
PUBLIC PendSV_Handler
PUBLIC SVC_Handler
PUBLIC vPortFreeSecureContext
#if ( configENABLE_FPU == 1 )
#error Cortex-M23 does not have a Floating Point Unit (FPU) and therefore configENABLE_FPU must be set to 0.
#endif
/*-----------------------------------------------------------*/
/*---------------- Unprivileged Functions -------------------*/
/*-----------------------------------------------------------*/
SECTION .text:CODE:NOROOT(2)
THUMB
/*-----------------------------------------------------------*/
xIsPrivileged:
mrs r0, control /* r0 = CONTROL. */
movs r1, #1 /* r1 = 1. */
tst r0, r1 /* Perform r0 & r1 (bitwise AND) and update the conditions flag. */
beq running_privileged /* If the result of previous AND operation was 0, branch. */
movs r0, #0 /* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
bx lr /* Return. */
running_privileged:
movs r0, #1 /* CONTROL[0]==0. Return true to indicate that the processor is privileged. */
bx lr /* Return. */
/*-----------------------------------------------------------*/
vResetPrivilege:
mrs r0, control /* r0 = CONTROL. */
movs r1, #1 /* r1 = 1. */
orrs r0, r1 /* r0 = r0 | r1. */
msr control, r0 /* CONTROL = r0. */
bx lr /* Return to the caller. */
/*-----------------------------------------------------------*/
vPortAllocateSecureContext:
svc 0 /* Secure context is allocated in the supervisor call. portSVC_ALLOCATE_SECURE_CONTEXT = 0. */
bx lr /* Return. */
/*-----------------------------------------------------------*/
/*----------------- Privileged Functions --------------------*/
/*-----------------------------------------------------------*/
SECTION privileged_functions:CODE:NOROOT(2)
THUMB
/*-----------------------------------------------------------*/
vRestoreContextOfFirstTask:
ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r3, [r2] /* Read pxCurrentTCB. */
ldr r0, [r3] /* 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. */
movs r5, #1 /* r5 = 1. */
bics r4, r5 /* r4 = r4 & ~r5 i.e. Clear the bit 0 in r4. */
str r4, [r2] /* Disable MPU. */
adds r3, #4 /* r3 = r3 + 4. r3 now points to MAIR0 in TCB. */
ldr r4, [r3] /* r4 = *r3 i.e. r4 = MAIR0. */
ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
str r4, [r2] /* Program MAIR0. */
ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
adds r3, #4 /* r3 = r3 + 4. r3 now points to first RBAR in TCB. */
movs r5, #4 /* r5 = 4. */
str r5, [r2] /* Program RNR = 4. */
ldmia r3!, {r6,r7} /* Read first set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write first set of RBAR/RLAR registers. */
movs r5, #5 /* r5 = 5. */
str r5, [r2] /* Program RNR = 5. */
ldmia r3!, {r6,r7} /* Read second set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write second set of RBAR/RLAR registers. */
movs r5, #6 /* r5 = 6. */
str r5, [r2] /* Program RNR = 6. */
ldmia r3!, {r6,r7} /* Read third set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write third set of RBAR/RLAR registers. */
movs r5, #7 /* r5 = 7. */
str r5, [r2] /* Program RNR = 7. */
ldmia r3!, {r6,r7} /* Read fourth set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write fourth set of RBAR/RLAR registers. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
movs r5, #1 /* r5 = 1. */
orrs r4, r5 /* r4 = r4 | r5 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-r4} /* Read from stack - r1 = xSecureContext, r2 = PSPLIM, r3 = CONTROL and r4 = EXC_RETURN. */
ldr r5, =xSecureContext
str r1, [r5] /* Set xSecureContext to this task's value for the same. */
msr psplim, r2 /* Set this task's PSPLIM value. */
msr control, r3 /* 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 r4 /* Finally, branch to EXC_RETURN. */
#else /* configENABLE_MPU */
ldm r0!, {r1-r3} /* Read from stack - r1 = xSecureContext, r2 = PSPLIM and r3 = EXC_RETURN. */
ldr r4, =xSecureContext
str r1, [r4] /* Set xSecureContext to this task's value for the same. */
msr psplim, r2 /* 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 r3 /* Finally, branch to EXC_RETURN. */
#endif /* configENABLE_MPU */
/*-----------------------------------------------------------*/
vRaisePrivilege:
mrs r0, control /* Read the CONTROL register. */
movs r1, #1 /* r1 = 1. */
bics r0, r1 /* 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. */
dsb
isb
svc 2 /* System call to start the first task. portSVC_START_SCHEDULER = 2. */
/*-----------------------------------------------------------*/
ulSetInterruptMaskFromISR:
mrs r0, PRIMASK
cpsid i
bx lr
/*-----------------------------------------------------------*/
vClearInterruptMaskFromISR:
msr PRIMASK, r0
bx lr
/*-----------------------------------------------------------*/
PendSV_Handler:
mrs r1, psp /* Read PSP in r1. */
ldr r2, =xSecureContext /* Read the location of xSecureContext i.e. &( xSecureContext ). */
ldr r0, [r2] /* Read xSecureContext - Value of xSecureContext must be in r0 as it is used as a parameter later. */
cbz r0, save_ns_context /* No secure context to save. */
push {r0-r2, r14}
bl SecureContext_SaveContext
pop {r0-r3} /* LR is now in r3. */
mov lr, r3 /* LR = r3. */
lsls r2, r3, #25 /* r2 = r3 << 25. Bit[6] of EXC_RETURN is 1 if secure stack was used, 0 if non-secure stack was used to store stack frame. */
bpl save_ns_context /* bpl - branch if positive or zero. If r2 >= 0 ==> Bit[6] in EXC_RETURN is 0 i.e. non-secure stack was used. */
ldr r3, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r2, [r3] /* Read pxCurrentTCB. */
#if ( configENABLE_MPU == 1 )
subs r1, r1, #16 /* Make space for xSecureContext, PSPLIM, CONTROL and LR on the stack. */
str r1, [r2] /* Save the new top of stack in TCB. */
mrs r2, psplim /* r2 = PSPLIM. */
mrs r3, control /* r3 = CONTROL. */
mov r4, lr /* r4 = LR/EXC_RETURN. */
stmia r1!, {r0, r2-r4} /* Store xSecureContext, PSPLIM, CONTROL and LR on the stack. */
#else /* configENABLE_MPU */
subs r1, r1, #12 /* Make space for xSecureContext, PSPLIM and LR on the stack. */
str r1, [r2] /* Save the new top of stack in TCB. */
mrs r2, psplim /* r2 = PSPLIM. */
mov r3, lr /* r3 = LR/EXC_RETURN. */
stmia r1!, {r0, r2-r3} /* Store xSecureContext, PSPLIM and LR on the stack. */
#endif /* configENABLE_MPU */
b select_next_task
save_ns_context:
ldr r3, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r2, [r3] /* Read pxCurrentTCB. */
#if ( configENABLE_MPU == 1 )
subs r1, r1, #48 /* Make space for xSecureContext, PSPLIM, CONTROL, LR and the remaining registers on the stack. */
str r1, [r2] /* Save the new top of stack in TCB. */
adds r1, r1, #16 /* r1 = r1 + 16. */
stmia r1!, {r4-r7} /* Store the low registers that are not saved automatically. */
mov r4, r8 /* r4 = r8. */
mov r5, r9 /* r5 = r9. */
mov r6, r10 /* r6 = r10. */
mov r7, r11 /* r7 = r11. */
stmia r1!, {r4-r7} /* Store the high registers that are not saved automatically. */
mrs r2, psplim /* r2 = PSPLIM. */
mrs r3, control /* r3 = CONTROL. */
mov r4, lr /* r4 = LR/EXC_RETURN. */
subs r1, r1, #48 /* r1 = r1 - 48. */
stmia r1!, {r0, r2-r4} /* Store xSecureContext, PSPLIM, CONTROL and LR on the stack. */
#else /* configENABLE_MPU */
subs r1, r1, #44 /* Make space for xSecureContext, PSPLIM, LR and the remaining registers on the stack. */
str r1, [r2] /* Save the new top of stack in TCB. */
mrs r2, psplim /* r2 = PSPLIM. */
mov r3, lr /* r3 = LR/EXC_RETURN. */
stmia r1!, {r0, r2-r7} /* Store xSecureContext, PSPLIM, LR and the low registers that are not saved automatically. */
mov r4, r8 /* r4 = r8. */
mov r5, r9 /* r5 = r9. */
mov r6, r10 /* r6 = r10. */
mov r7, r11 /* r7 = r11. */
stmia r1!, {r4-r7} /* Store the high registers that are not saved automatically. */
#endif /* configENABLE_MPU */
select_next_task:
cpsid i
bl vTaskSwitchContext
cpsie i
ldr r2, =pxCurrentTCB /* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
ldr r3, [r2] /* Read pxCurrentTCB. */
ldr r1, [r3] /* The first item in pxCurrentTCB is the task top of stack. r1 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. */
movs r5, #1 /* r5 = 1. */
bics r4, r5 /* r4 = r4 & ~r5 i.e. Clear the bit 0 in r4. */
str r4, [r2] /* Disable MPU. */
adds r3, #4 /* r3 = r3 + 4. r3 now points to MAIR0 in TCB. */
ldr r4, [r3] /* r4 = *r3 i.e. r4 = MAIR0. */
ldr r2, =0xe000edc0 /* r2 = 0xe000edc0 [Location of MAIR0]. */
str r4, [r2] /* Program MAIR0. */
ldr r2, =0xe000ed98 /* r2 = 0xe000ed98 [Location of RNR]. */
adds r3, #4 /* r3 = r3 + 4. r3 now points to first RBAR in TCB. */
movs r5, #4 /* r5 = 4. */
str r5, [r2] /* Program RNR = 4. */
ldmia r3!, {r6,r7} /* Read first set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write first set of RBAR/RLAR registers. */
movs r5, #5 /* r5 = 5. */
str r5, [r2] /* Program RNR = 5. */
ldmia r3!, {r6,r7} /* Read second set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write second set of RBAR/RLAR registers. */
movs r5, #6 /* r5 = 6. */
str r5, [r2] /* Program RNR = 6. */
ldmia r3!, {r6,r7} /* Read third set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write third set of RBAR/RLAR registers. */
movs r5, #7 /* r5 = 7. */
str r5, [r2] /* Program RNR = 7. */
ldmia r3!, {r6,r7} /* Read fourth set of RBAR/RLAR from TCB. */
ldr r4, =0xe000ed9c /* r4 = 0xe000ed9c [Location of RBAR]. */
stmia r4!, {r6,r7} /* Write fourth set of RBAR/RLAR registers. */
ldr r2, =0xe000ed94 /* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
ldr r4, [r2] /* Read the value of MPU_CTRL. */
movs r5, #1 /* r5 = 1. */
orrs r4, r5 /* r4 = r4 | r5 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 r1!, {r0, r2-r4} /* Read from stack - r0 = xSecureContext, r2 = PSPLIM, r3 = CONTROL and r4 = LR. */
msr psplim, r2 /* Restore the PSPLIM register value for the task. */
msr control, r3 /* Restore the CONTROL register value for the task. */
mov lr, r4 /* LR = r4. */
ldr r2, =xSecureContext /* Read the location of xSecureContext i.e. &( xSecureContext ). */
str r0, [r2] /* Restore the task's xSecureContext. */
cbz r0, restore_ns_context /* If there is no secure context for the task, restore the non-secure context. */
push {r1,r4}
bl SecureContext_LoadContext /* Restore the secure context. */
pop {r1,r4}
mov lr, r4 /* LR = r4. */
lsls r2, r4, #25 /* r2 = r4 << 25. Bit[6] of EXC_RETURN is 1 if secure stack was used, 0 if non-secure stack was used to store stack frame. */
bpl restore_ns_context /* bpl - branch if positive or zero. If r2 >= 0 ==> Bit[6] in EXC_RETURN is 0 i.e. non-secure stack was used. */
msr psp, r1 /* Remember the new top of stack for the task. */
bx lr
#else /* configENABLE_MPU */
ldmia r1!, {r0, r2-r3} /* Read from stack - r0 = xSecureContext, r2 = PSPLIM and r3 = LR. */
msr psplim, r2 /* Restore the PSPLIM register value for the task. */
mov lr, r3 /* LR = r3. */
ldr r2, =xSecureContext /* Read the location of xSecureContext i.e. &( xSecureContext ). */
str r0, [r2] /* Restore the task's xSecureContext. */
cbz r0, restore_ns_context /* If there is no secure context for the task, restore the non-secure context. */
push {r1,r3}
bl SecureContext_LoadContext /* Restore the secure context. */
pop {r1,r3}
mov lr, r3 /* LR = r3. */
lsls r2, r3, #25 /* r2 = r3 << 25. Bit[6] of EXC_RETURN is 1 if secure stack was used, 0 if non-secure stack was used to store stack frame. */
bpl restore_ns_context /* bpl - branch if positive or zero. If r2 >= 0 ==> Bit[6] in EXC_RETURN is 0 i.e. non-secure stack was used. */
msr psp, r1 /* Remember the new top of stack for the task. */
bx lr
#endif /* configENABLE_MPU */
restore_ns_context:
adds r1, r1, #16 /* Move to the high registers. */
ldmia r1!, {r4-r7} /* Restore the high registers that are not automatically restored. */
mov r8, r4 /* r8 = r4. */
mov r9, r5 /* r9 = r5. */
mov r10, r6 /* r10 = r6. */
mov r11, r7 /* r11 = r7. */
msr psp, r1 /* Remember the new top of stack for the task. */
subs r1, r1, #32 /* Go back to the low registers. */
ldmia r1!, {r4-r7} /* Restore the low registers that are not automatically restored. */
bx lr
/*-----------------------------------------------------------*/
SVC_Handler:
movs r0, #4
mov r1, lr
tst r0, r1
beq stacking_used_msp
mrs r0, psp
b vPortSVCHandler_C
stacking_used_msp:
mrs r0, msp
b vPortSVCHandler_C
/*-----------------------------------------------------------*/
vPortFreeSecureContext:
ldr r1, [r0] /* The first item in the TCB is the top of the stack. */
ldr r0, [r1] /* The first item on the stack is the task's xSecureContext. */
cmp r0, #0 /* Raise svc if task's xSecureContext is not NULL. */
beq free_secure_context
bx lr /* There is no secure context (xSecureContext is NULL). */
free_secure_context:
svc 1 /* Secure context is freed in the supervisor call. portSVC_FREE_SECURE_CONTEXT = 1. */
bx lr /* Return. */
/*-----------------------------------------------------------*/
END