From 6913e2fcbc9e876c1eb40dbf69301bc5e0aca4b7 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Wed, 19 Jan 2022 12:02:34 -0700
Subject: Fixed IRQ bug
Updated handlers
Started filling svc calls
---
src/boot.S | 97 +++++++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 67 insertions(+), 30 deletions(-)
(limited to 'src')
diff --git a/src/boot.S b/src/boot.S
index 6bb24ae..da2d602 100644
--- a/src/boot.S
+++ b/src/boot.S
@@ -24,9 +24,32 @@ reset:
orr r1, r1, #0x12
msr cpsr_c,r1
mov sp,#0x4000
+ // setup sp in FIQ mode.
+ bic r1, r0, #0x1f
+ orr r1, r1, #0x11
+ msr cpsr_c,r1
+ mov sp,#0x2000
+ // setup sp in UNDEF mode.
+ bic r1, r0, #0x1f
+ orr r1, r1, #0x1B
+ msr cpsr_c,r1
+ mov sp,#0x1000
+ // setup sp in ABORT mode.
+ bic r1, r0, #0x1f
+ orr r1, r1, #0x17
+ msr cpsr_c,r1
+ mov sp,#0x0800
+ // Setup sp in USR/SYS mode.
+ bic r1, r0, #0x1f
+ orr r1, r1, #0x1f
+ msr cpsr_c,r1
+ mov sp,#0x6000
- // restore cpsr.
- msr cpsr_c, r0
+ // restore to SVC (in the case of a reset)
+ bic r1, r0, #0x1f
+ orr r1, r1, #0x13
+ msr cpsr_c, r1
+ //msr cpsr_c, r0
// setup the stack in SVC mode.
mov sp, #0x8000
@@ -55,9 +78,7 @@ reset:
irq:
push {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
- cpsid i
bl c_irq_handler
- cpsie i
pop {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
subs pc, lr, #4
@@ -66,47 +87,63 @@ io_halt:
wfi
b io_halt
-io_halt_undefined:
+// TODO: SETUP OTHER STACKS
+undefined:
stmfd sp!, {r0-r12,lr}
- ldr r0, [lr, #-8]
+ ldr r0, [lr, #-4]
push {r0}
ldr r0, =undefined_msg
bl uart_string
pop {r0}
+ bl uart_hex
+ ldr r0, =undefined_at
+ bl uart_string
+ // Output lr
+ mov r1, #0x1000
+ ldr r0, [r1, #-4]
bl uart_hexn
// Skip instruction for now
// In future,
- // ldmfd ... pc->lr
- // subs pc, lr, #8
+ // ldmfd sp!, {r0-r12,lr} // Note the lack of ^ since subs will handle it
+ // subs pc, lr, #4
ldmfd sp!, {r0-r12,pc}^
-io_halt_swi:
+svc:
stmfd sp!, {r0-r12,lr}
ldr r0, [lr, #-4]
bic r0, #0xFF000000
push {r0}
- ldr r0, =swi_msg
+ ldr r0, =svc_msg
bl uart_string
- pop {r0}
+ ldr r0, [sp]
bl uart_hexn
+ pop {r0}
+ // SVC #0 returns to supervisor mode
+ // TODO: Make supervisor mode return to a specific location
+ // (rather than to a user location) such as the kernel loop
+ cmp r0, #0
+ bne 1f
+ mrs r0, spsr
+ bic r0, #0x1f
+ // Return in supervisor mode
+ orr r0, #0x13
+ msr spsr, r0
+1:
ldmfd sp!, {r0-r12,pc}^
io_halt_prefetch:
+ stmfd sp!, {r0-r12,lr}
ldr r0, =prefetch_msg
- push {lr}
bl uart_string
- pop {lr}
- b io_halt
+ ldmfd sp!, {r0-r12,pc}^
io_halt_data:
+ stmfd sp!, {r0-r12,lr}
ldr r0, =data_msg
- push {lr}
- bl uart_string
- pop {lr}
- b io_halt
-io_halt_unused:
- ldr r0, =unused_msg
- push {lr}
bl uart_string
- pop {lr}
- b io_halt
+ // Output return address
+ mov r1, #0x800
+ ldr r0, [r1, #-4]
+ sub r0, #8
+ bl uart_hexn
+ ldmfd sp!, {r0-r12,pc}^
io_halt_fiq:
ldr r0, =fiq_msg
push {lr}
@@ -118,7 +155,7 @@ io_halt_fiq:
vector:
ldr pc, reset_handler
ldr pc, undefined_handler
- ldr pc, swi_handler
+ ldr pc, svc_handler
ldr pc, prefetch_handler
ldr pc, data_handler
ldr pc, unused_handler
@@ -126,18 +163,18 @@ vector:
ldr pc, fiq_handler
reset_handler: .word reset
-undefined_handler: .word io_halt_undefined
-swi_handler: .word io_halt_swi
+undefined_handler: .word undefined
+svc_handler: .word svc
prefetch_handler: .word io_halt_prefetch
data_handler: .word io_halt_data
-unused_handler: .word io_halt_unused
+unused_handler: .word io_halt
irq_handler: .word irq
fiq_handler: .word io_halt_fiq
.section .data
-undefined_msg: .asciz "Undefined Handler\n"
-swi_msg: .asciz "SWI Handler\n"
+undefined_msg: .asciz "Undefined Handler\nUNDEF "
+undefined_at: .asciz " @ 0x"
+svc_msg: .asciz "SVC Handler\nSVC #"
prefetch_msg: .asciz "Prefetch Handler\n"
data_msg: .asciz "Data Handler\n"
-unused_msg: .asciz "Unused Handler\n"
fiq_msg: .asciz "FIQ\n"
--
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