From dd0e90c84db6743141eeaabacb51bc8539d4eaf0 Mon Sep 17 00:00:00 2001
From: Ali Mashtizadeh <mashti@cs.stanford.edu>
Date: Sun, 13 Jul 2014 13:07:19 -0700
Subject: [PATCH] Starting Kernel Debugger

---
 sys/amd64/debug.c   | 29 +++++++++++++++++++++++++++++
 sys/amd64/machine.c |  2 ++
 sys/amd64/trap.c    |  8 ++++++++
 sys/kern/debug.c    | 18 ++++++++++++++++++
 4 files changed, 57 insertions(+)
 create mode 100644 sys/amd64/debug.c

diff --git a/sys/amd64/debug.c b/sys/amd64/debug.c
new file mode 100644
index 0000000..bbba551
--- /dev/null
+++ b/sys/amd64/debug.c
@@ -0,0 +1,29 @@
+
+#include <stdint.h>
+
+#include <kassert.h>
+#include <kconfig.h>
+//#include <kdebug.h>
+#include <mp.h>
+
+#include "trap.h"
+
+TrapFrame *frames[MAX_CPUS];
+
+void
+Debug_Breakpoint(TrapFrame *tf)
+{
+    frames[CPU()] = tf;
+
+    // Stop all processors
+
+    Debug_Prompt();
+
+    // Resume all processors
+}
+
+void
+Debug_Registers(int argc, const char *argv[])
+{
+}
+
diff --git a/sys/amd64/machine.c b/sys/amd64/machine.c
index e1e125e..caf77f8 100644
--- a/sys/amd64/machine.c
+++ b/sys/amd64/machine.c
@@ -101,5 +101,7 @@ void Machine_Init()
 
     PCI_Init();
     IDE_Init();
+
+    breakpoint();
 }
 
diff --git a/sys/amd64/trap.c b/sys/amd64/trap.c
index daa54bc..94e32a9 100644
--- a/sys/amd64/trap.c
+++ b/sys/amd64/trap.c
@@ -87,11 +87,19 @@ Trap_Dump(TrapFrame *tf)
 void
 trap_entry(TrapFrame *tf)
 {
+    // Kernel Debugger
+    if (tf->vector == T_BP && tf->cs == SEL_KCS)
+    {
+	Debug_Breakpoint(tf);
+	return;
+    }
+
     // Halt on kernel errors
     if (tf->vector <= T_CPU_LAST && tf->cs == SEL_KCS)
     {
 	kprintf("Kernel Fault!\n");
 	Trap_Dump(tf);
+	Debug_Breakpoint(tf);
 	while (1)
 	    hlt();
     }
diff --git a/sys/kern/debug.c b/sys/kern/debug.c
index fadd76e..d1f32c6 100644
--- a/sys/kern/debug.c
+++ b/sys/kern/debug.c
@@ -70,3 +70,21 @@ Debug_PrintHex(const char *data, size_t length, off_t off, size_t limit)
     }
 }
 
+void
+Debug_Dump(int argc, const char *argv[])
+{
+}
+
+void
+Debug_Prompt()
+{
+    kprintf("Entered Debugger!\n");
+
+    kprintf("> ");
+    // read input
+
+    // parse input
+
+    // execute command
+}
+