From a1f49718aee378fa075303c86106309091d56b80 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Mon, 31 Jan 2022 19:05:50 -0700
Subject: Break exceptions off to own files

---
 src/exceptions/data.S      | 29 +++++++++++++++++++++++++++++
 src/exceptions/fiq.S       | 26 ++++++++++++++++++++++++++
 src/exceptions/irq.S       |  8 ++++++++
 src/exceptions/prefetch.S  | 20 ++++++++++++++++++++
 src/exceptions/svc.S       | 45 +++++++++++++++++++++++++++++++++++++++++++++
 src/exceptions/undefined.S | 34 ++++++++++++++++++++++++++++++++++
 6 files changed, 162 insertions(+)
 create mode 100644 src/exceptions/data.S
 create mode 100644 src/exceptions/fiq.S
 create mode 100644 src/exceptions/irq.S
 create mode 100644 src/exceptions/prefetch.S
 create mode 100644 src/exceptions/svc.S
 create mode 100644 src/exceptions/undefined.S

(limited to 'src/exceptions')

diff --git a/src/exceptions/data.S b/src/exceptions/data.S
new file mode 100644
index 0000000..2268de5
--- /dev/null
+++ b/src/exceptions/data.S
@@ -0,0 +1,29 @@
+.section ".text.exceptions"
+.globl data
+data:
+	cpsid aif
+	stmfd sp!, {r0-r12,lr}
+	mov r4, lr
+	mov r0, #0
+	mov r1, #15
+	ldr r2, =data_msg
+	bl draw_string
+	// Output return address
+	mov r0, #13
+	mov r1, #15
+	mov r2, r4
+	sub r2, #8
+	bl draw_hex32
+	mov r0, #22
+	mov r1, #15
+	ldr r2, [r4, #-8]
+	bl draw_hex32
+	mov r0, #32
+	mov r1, #15
+	mrs r2, spsr
+	bl draw_hex32
+	ldmfd sp!, {r0-r12,lr}
+	subs pc, lr, #4 // Should be 8 once I can actually handle the abort
+
+.section .data
+data_msg:	.asciz "Data Handler"
diff --git a/src/exceptions/fiq.S b/src/exceptions/fiq.S
new file mode 100644
index 0000000..f323a02
--- /dev/null
+++ b/src/exceptions/fiq.S
@@ -0,0 +1,26 @@
+.section ".text.exceptions"
+.globl fiq
+fiq:
+	cpsid aif
+	stmfd sp!, {r0-r12,lr}
+	bl c_fiq_handler
+	cmp r0, #1
+	bne 1f
+	mrs r1, spsr
+	and r1, r1, #0x1f
+	cmp r1, #0x10
+	bne 1f
+	ldmfd sp!, {r0-r12,lr}
+	sub lr, #4
+	push {r3}
+	ldr r3, =irqlr
+	str lr, [r3, #0]
+	pop {r3}
+	cps #0x13
+	b schedule
+1:
+	ldmfd sp!, {r0-r12,lr}
+	subs pc, lr, #4
+
+.section .data
+fiq_msg:	.asciz "FIQ\n"
diff --git a/src/exceptions/irq.S b/src/exceptions/irq.S
new file mode 100644
index 0000000..025fc41
--- /dev/null
+++ b/src/exceptions/irq.S
@@ -0,0 +1,8 @@
+.section ".text.exceptions"
+.globl irq
+irq:
+	cpsid aif
+	push {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
+	bl c_irq_handler
+	pop  {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
+	subs pc, lr, #4
diff --git a/src/exceptions/prefetch.S b/src/exceptions/prefetch.S
new file mode 100644
index 0000000..1aeba10
--- /dev/null
+++ b/src/exceptions/prefetch.S
@@ -0,0 +1,20 @@
+.section ".text.exceptions"
+.globl prefetch
+prefetch:
+	cpsid aif
+	stmfd sp!, {r0-r12,lr}
+	mov r4, lr
+	mov r0, #0
+	mov r1, #16
+	ldr r2, =prefetch_msg
+	bl draw_string
+	// Output return address
+	mov r0, #17
+	mov r1, #16
+	mov r2, r4
+	bl draw_hex32
+	ldmfd sp!, {r0-r12,lr}
+	subs pc, lr, #4
+
+.section .data
+prefetch_msg:	.asciz "Prefetch Handler"
diff --git a/src/exceptions/svc.S b/src/exceptions/svc.S
new file mode 100644
index 0000000..a5e9982
--- /dev/null
+++ b/src/exceptions/svc.S
@@ -0,0 +1,45 @@
+.section ".text.exceptions"
+.globl svc
+svc:
+	cpsid aif
+	stmfd sp!, {r0-r12,lr}
+	ldr r0, [lr, #-4]
+	bic r0, #0xFF000000
+	// 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, #3
+	bgt svc_exit
+	beq svc_000003
+	cmp r0, #2
+	beq svc_000002
+	cmp r0, #1
+	beq svc_000001
+	cmp r0, #1
+	beq svc_000000
+svc_000000:
+	cps #0x13
+	b svc_exit
+svc_000001:
+	b svc_exit
+svc_000002:
+	ldmfd sp!, {r0-r12,lr}
+	b schedule
+svc_000003:
+	ldr r3, =scheduler
+	ldr r2, [r3, #0]
+	ldr r1, [r2, #8] // sp_base
+	cmp r1, #-1
+	beq svc_exit
+	ldr r3, =stacks_table
+	mov r0, #0
+	strb r0, [r3, r1]
+	// Free the thread after freeing the stack
+	mov r0, r2
+	bl free
+	b svc_exit
+svc_exit:
+	ldmfd sp!, {r0-r12,pc}^
+
+.section .data
+svc_msg:	.asciz "SVC Handler #"
diff --git a/src/exceptions/undefined.S b/src/exceptions/undefined.S
new file mode 100644
index 0000000..b8eab29
--- /dev/null
+++ b/src/exceptions/undefined.S
@@ -0,0 +1,34 @@
+.section ".text.exceptions"
+.globl undefined
+undefined:
+	cpsid aif
+	stmfd sp!, {r0-r12,lr}
+	ldr r4, [lr, #-4]
+	mov r0, #0
+	mov r1, #17
+	ldr r2, =undefined_msg
+	bl draw_string
+	mov r0, #18
+	mov r1, #17
+	mov r2, r4
+	bl draw_hex32
+	mov r0, #27
+	mov r1, #17
+	ldr r2, =undefined_at
+	bl draw_string
+	// Output lr
+	mov r1, #0x1000
+	ldr r0, [r1, #-4]
+	sub r2, r0, #4
+	mov r0, #31
+	mov r1, #17
+	bl draw_hex32
+	// Skip instruction for now
+	// In future, 
+	//  ldmfd sp!, {r0-r12,lr} // Note the lack of ^ since subs will handle it
+	//  subs pc, lr, #4
+	ldmfd sp!, {r0-r12,pc}^
+
+.section .data
+undefined_msg:	.asciz "Undefined Handler"
+undefined_at:	.asciz "@ 0x"
-- 
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