From d213712d4f858efd5cb43faa39c6d940829c9363 Mon Sep 17 00:00:00 2001
From: AJFISH <AJFISH@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Fri, 8 Jan 2010 23:07:33 +0000
Subject: [PATCH] Fixed a bug in the HardwareInterrupt handler that would blow
 the stack if you reenable interrupts in the TimerHandler. It should be noted
 this happens as the TimerHandler raises and restores TPL for the timer tick
 used by the DXE Core. There was some work around code in the CPU driver to
 prevent interrupts from being enabled while handling exceptions. This has
 been removed.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9701 6f19259b-4bc3-4df7-8a09-765794883524
---
 ArmPkg/Drivers/CpuDxe/CpuDxe.c                  | 9 ++-------
 ArmPkg/Drivers/CpuDxe/Exception.c               | 7 +------
 BeagleBoardPkg/InterruptDxe/HardwareInterrupt.c | 4 ++++
 3 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.c b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
index 2b43d2a9c9..d3f0ff505d 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.c
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
@@ -14,7 +14,6 @@
 
 #include "CpuDxe.h"
 
-BOOLEAN gExceptionContext = FALSE;
 BOOLEAN mInterruptState   = FALSE;
 
 EFI_STATUS
@@ -49,9 +48,7 @@ CpuEnableInterrupt (
   IN EFI_CPU_ARCH_PROTOCOL          *This
   )
 {
-  if (!gExceptionContext) {
-    ArmEnableInterrupts ();
-  }
+  ArmEnableInterrupts ();
 
   mInterruptState  = TRUE;
   return EFI_SUCCESS;
@@ -64,9 +61,7 @@ CpuDisableInterrupt (
   IN EFI_CPU_ARCH_PROTOCOL          *This
   )
 {
-  if (!gExceptionContext) {
-    ArmDisableInterrupts ();
-  }
+  ArmDisableInterrupts ();
 
   mInterruptState = FALSE;
   return EFI_SUCCESS;
diff --git a/ArmPkg/Drivers/CpuDxe/Exception.c b/ArmPkg/Drivers/CpuDxe/Exception.c
index 8859ca8667..9910bd2b88 100644
--- a/ArmPkg/Drivers/CpuDxe/Exception.c
+++ b/ArmPkg/Drivers/CpuDxe/Exception.c
@@ -15,8 +15,6 @@
 #include "CpuDxe.h" 
 #include <Library/CacheMaintenanceLib.h>
 
-extern BOOLEAN gExceptionContext;
-
 VOID
 ExceptionHandlersStart (
   VOID
@@ -142,8 +140,7 @@ CommonCExceptionHandler (
 {
   BOOLEAN Dispatched = FALSE;
  
-  gExceptionContext = TRUE; 
-  
+ 
   if (ExceptionType <= MAX_ARM_EXCEPTION) {
     if (gDebuggerExceptionHandlers[ExceptionType]) {
       //
@@ -162,8 +159,6 @@ CommonCExceptionHandler (
     ASSERT (FALSE);
   }
 
-  gExceptionContext = FALSE; 
-
   if (Dispatched) {
     //
     // We did work so this was an expected ExceptionType
diff --git a/BeagleBoardPkg/InterruptDxe/HardwareInterrupt.c b/BeagleBoardPkg/InterruptDxe/HardwareInterrupt.c
index 3e69515dfe..c87d564063 100644
--- a/BeagleBoardPkg/InterruptDxe/HardwareInterrupt.c
+++ b/BeagleBoardPkg/InterruptDxe/HardwareInterrupt.c
@@ -234,12 +234,16 @@ IrqInterruptHandler (
   
   Vector = MmioRead32(INTCPS_SIR_IRQ) & INTCPS_SIR_IRQ_MASK;
 
+  // Needed to prevent infinite nesting if Time Driver lowers TPL
+  MmioWrite32(INTCPS_CONTROL, INTCPS_CONTROL_NEWIRQAGR);
+
   InterruptHandler = gRegisteredInterruptHandlers[Vector];
   if (InterruptHandler != NULL) {
     // Call the registered interrupt handler.
     InterruptHandler(Vector, SystemContext);
   }
   
+  // Needed to clear after running the handler
   MmioWrite32(INTCPS_CONTROL, INTCPS_CONTROL_NEWIRQAGR);
 }
 
-- 
2.39.2