/* | |
* FreeRTOS Kernel <DEVELOPMENT BRANCH> | |
* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved. | |
* | |
* SPDX-License-Identifier: MIT | |
* | |
* 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. | |
* | |
* https://www.FreeRTOS.org | |
* https://github.com/FreeRTOS | |
* | |
*/ | |
.extern vTaskSwitchContext | |
.set noat | |
# Exported to start the first task. | |
.globl restore_sp_from_pxCurrentTCB | |
# Entry point for exceptions. | |
.section .exceptions.entry.user, "xa" | |
# Save the entire context of a task. | |
save_context: | |
addi sp, sp, -116 # Create space on the stack. | |
stw ra, 0(sp) | |
# Leave a gap for muldiv 0 | |
stw at, 8(sp) | |
stw r2, 12(sp) | |
stw r3, 16(sp) | |
stw r4, 20(sp) | |
stw r5, 24(sp) | |
stw r6, 28(sp) | |
stw r7, 32(sp) | |
stw r8, 36(sp) | |
stw r9, 40(sp) | |
stw r10, 44(sp) | |
stw r11, 48(sp) | |
stw r12, 52(sp) | |
stw r13, 56(sp) | |
stw r14, 60(sp) | |
stw r15, 64(sp) | |
rdctl r5, estatus # Save the eStatus | |
stw r5, 68(sp) | |
addi r15, ea, -4 # Instruction that caused exception | |
stw r15, 72(sp) # Save as EA | |
stw r16, 76(sp) # Save the remaining registers | |
stw r17, 80(sp) | |
stw r18, 84(sp) | |
stw r19, 88(sp) | |
stw r20, 92(sp) | |
stw r21, 96(sp) | |
stw r22, 100(sp) | |
stw r23, 104(sp) | |
stw gp, 108(sp) | |
stw fp, 112(sp) | |
save_sp_to_pxCurrentTCB: | |
movia et, pxCurrentTCB # Load the address of the pxCurrentTCB pointer | |
ldw et, (et) # Load the value of the pxCurrentTCB pointer | |
stw sp, (et) # Store the stack pointer into the top of the TCB | |
br irq_test_user # skip the section .exceptions.entry | |
.section .exceptions.irqtest, "xa" | |
irq_test_user: | |
.section .exceptions.exit.user, "xa" | |
restore_sp_from_pxCurrentTCB: | |
movia et, pxCurrentTCB # Load the address of the pxCurrentTCB pointer | |
ldw et, (et) # Load the value of the pxCurrentTCB pointer | |
ldw sp, (et) # Load the stack pointer with the top value of the TCB | |
restore_context: | |
ldw ra, 0(sp) # Restore the registers. | |
# Leave a gap for muldiv 0. | |
ldw at, 8(sp) | |
ldw r2, 12(sp) | |
ldw r3, 16(sp) | |
ldw r4, 20(sp) | |
ldw r5, 24(sp) | |
ldw r6, 28(sp) | |
ldw r7, 32(sp) | |
ldw r8, 36(sp) | |
ldw r9, 40(sp) | |
ldw r10, 44(sp) | |
ldw r11, 48(sp) | |
ldw r12, 52(sp) | |
ldw r13, 56(sp) | |
ldw r14, 60(sp) | |
ldw r15, 64(sp) | |
ldw et, 68(sp) # Load the eStatus | |
wrctl estatus, et # Write the eStatus | |
ldw ea, 72(sp) # Load the Program Counter | |
ldw r16, 76(sp) | |
ldw r17, 80(sp) | |
ldw r18, 84(sp) | |
ldw r19, 88(sp) | |
ldw r20, 92(sp) | |
ldw r21, 96(sp) | |
ldw r22, 100(sp) | |
ldw r23, 104(sp) | |
ldw gp, 108(sp) | |
ldw fp, 112(sp) | |
addi sp, sp, 116 # Release stack space | |
eret # Return to address ea, loading eStatus into Status. | |
.section .exceptions.soft, "xa" | |
soft_exceptions: | |
movhi r3, 0x003b /* upper half of trap opcode */ | |
ori r3, r3, 0x683a /* lower half of trap opcode */ | |
beq r2, r3, call_scheduler | |
br exceptions_unknown_user # its something else | |
call_scheduler: | |
stw ea, 72(sp) # EA is PC+4 so will skip over instruction causing exception | |
call vTaskSwitchContext # Pick the next context. | |
br restore_sp_from_pxCurrentTCB # Switch in the task context and restore. | |
.section .exceptions.unknown.user | |
exceptions_unknown_user: | |