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/*
ChibiOS - Copyright (C) 2019 Diego Ismirlian (dismirlian(at)google's mail)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
.syntax unified
.cpu cortex-m4
.section .data._fault_stack
.align 3
_fault_stack:
.skip 256
_fault_stack_end:
.thumb
.section .text.HardFault_Handler
.thumb_func
.globl HardFault_Handler
HardFault_Handler:
/* disable further interrupts */
cpsid i
/* preserve the ISR sp for later */
mov r1, sp
/* set the sp to a separate stack, in case of sp corruption */
ldr sp, .L1
/* preserve the ISR lr and sp for later */
push {r1, lr}
/* print info */
bl _hardfault_info
/* restore the sp and the lr */
pop {r1, lr}
mov sp, r1
/* Try to rebuild the stack for the debugger.
* The idea is that the debugger will unwind the stack, and
* show a call to the HardFault_Handler from the offending
* instruction */
/* check which stack was in use */
tst lr, #4 //check bit 2 of EXC_RETURN
ite eq
mrseq r0, msp
mrsne r0, psp //r0 points to the stack that was in use
/* try to rebuild the stack for the debugger */
mov sp, r0 //sp points to the end of the IRQ stack
/* check if FPU registers were stacked */
tst lr, #16 //check bit 4 of EXC_RETURN
ite eq
addeq sp, #104 //jump over the IRQ+FPU stack
addne sp, #32 //jump over the IRQ stack
/* compensate padding */
ldr r1, [sp, #28] //r1 = stacked xPSR
tst r1, #512 //check bit 9 of the stacked xPSR
ite eq
addeq sp, #0 //add 0 to sp if there was no padding
addne sp, #4 //add 4 to sp if there was padding
/* here, sp finally points to the stack before the IRQ was triggered */
/* set lr to the stacked PC address, so the debugger can show where the
fault was produced (may not be accurate, depending on the fault) */
ldr lr, [r0, #24]
/* restore used registers */
ldr r0, [r0, #0]
ldr r1, [r0, #4]
b _hardfault_epilogue
.align 2
.L1: .word _fault_stack_end
.section .text._hardfault_exit
.thumb_func
.globl _hardfault_exit
_hardfault_exit:
/* we are here if there is no debugger attached */
/* restore the sp to the separate stack */
ldr sp, .L3
/* call chSysHalt */
ldr r0, =.L2
bl chSysHalt
b .
.align 2
.L3: .word _fault_stack_end
.align 2
.L2: .asciz "hard fault"
.align 2
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