From 7a15e00cc238051a2bb677159a665bc13e0c3d61 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sun, 13 Mar 2016 19:33:10 -0400
Subject: [PATCH] Add some system exception handlers and clean up assemply a
 bit

---
 src/Interrupts.cc | 19 +++++++++++++++----
 src/isr.S         | 27 +++++++++++++++++----------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/src/Interrupts.cc b/src/Interrupts.cc
index 97c5e12..607e5b3 100644
--- a/src/Interrupts.cc
+++ b/src/Interrupts.cc
@@ -11,11 +11,10 @@
 #include "IO.hh"
 
 extern "C" {
-    void dispatchExceptionHandler(size_t vector);
-
     // Assembly functions. See isr.S.
     void unhandledInterrupt();
     void handleDEException();
+    void handleNMIInterrupt();
     void handleDFException();
     void handleGPException();
     void handleHardwareInterrupt0();
@@ -50,14 +49,23 @@ InterruptHandler::initialize()
 {
     auto& console = kernel::Console::systemConsole();
 
+    // All interrupts start out as "unhandled"
     for (size_t i = 0; i < IDT::Size; i++) {
         mIDT.setDescriptor(i, IDT::DescriptorSpec::exceptionHandler(0x8, &unhandledInterrupt));
     }
+
+    // System exceptions/faults
+    mIDT.setDescriptor(0x00, IDT::DescriptorSpec::exceptionHandler(0x8, &handleDEException));
+    mIDT.setDescriptor(0x02, IDT::DescriptorSpec::exceptionHandler(0x8, &handleNMIInterrupt));
+    mIDT.setDescriptor(0x08, IDT::DescriptorSpec::exceptionHandler(0x8, &handleDFException));
+    mIDT.setDescriptor(0x0D, IDT::DescriptorSpec::exceptionHandler(0x8, &handleGPException));
+
+
+    // Hardware interrupts
     mIDT.setDescriptor(0x20, IDT::DescriptorSpec::exceptionHandler(0x8, &handleHardwareInterrupt0));
     mIDT.setDescriptor(0x21, IDT::DescriptorSpec::exceptionHandler(0x8, &handleHardwareInterrupt1));
-    mIDT.load();
 
-    console.printString("IDT loaded\n");
+    mIDT.load();
 
     mPIC.initialize(0x20, 0x28);  // Map hardware IRQs to interrupt vectors 32 through 48.
     console.printString("Hardware interrupts initialized\n");
@@ -164,6 +172,9 @@ InterruptHandler::finishHardwareInterrupt(uint8_t irq)
 
 } /* namespace x86 */
 
+/*
+ * Interrupt handlers
+ */
 
 extern "C"
 void
diff --git a/src/isr.S b/src/isr.S
index afe83ca..205dcf6 100644
--- a/src/isr.S
+++ b/src/isr.S
@@ -5,7 +5,7 @@
 
 .section .text
 .global unhandledInterrupt
-.global handleDEException, handleDFException, handleGPException
+.global handleDEException, handleNMIInterrupt, handleDFException, handleGPException
 .global handleHardwareInterrupt0, handleHardwareInterrupt1
 
 #define SaveContext \
@@ -21,15 +21,6 @@
     cli; \
     hlt
 
-#define SaveContextForHardwareInterrupt(irq) \
-    SaveContext \
-    pushl $irq
-
-#define RestoreContextForHardwareInterrupt(irq) \
-    addl $4, %esp; \
-    RestoreContext
-
-
 // Generic handler
 unhandledInterrupt:
     SaveContext
@@ -44,6 +35,14 @@ handleDEException:
     add $4, %esp
     RestoreContextAndHalt
 
+// NMI interrupt
+handleNMIInterrupt:
+    SaveContext
+    pushl $2
+    call dispatchExceptionHandler
+    add $4, %esp
+    RestoreContextAndHalt
+
 // Double fault
 handleDFException:
     SaveContext
@@ -64,6 +63,14 @@ handleGPException:
  * Hardware Interrupts
  */
 
+#define SaveContextForHardwareInterrupt(irq) \
+    SaveContext \
+    pushl $irq
+
+#define RestoreContextForHardwareInterrupt(irq) \
+    addl $4, %esp; \
+    RestoreContext
+
 handleHardwareInterrupt0:
     SaveContextForHardwareInterrupt(0)
     call dispatchHardwareInterrupt