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/svc.S | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 src/exceptions/svc.S

(limited to 'src/exceptions/svc.S')

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 #"
-- 
cgit v1.2.1