ArmPkg: Introduce the PCD PcdDebuggerExceptionSupport

The Exception Vector can be set before installing the CPU DXE driver to add
debugger support at the early stage of the firmware initialization.
If no one has touched the exception vector prior to the CPU DXE then the Vector
might contain non zero data.



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11733 6f19259b-4bc3-4df7-8a09-765794883524

2 files changed, 5 insertions, 1 deletions

diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.inf b/ArmPkg/Drivers/CpuDxe/CpuDxe.inf
index 25c0b880b2..e74de5b3e0 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.inf
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.inf
@@ -73,6 +73,7 @@
 [FeaturePcd.common]

   gArmTokenSpaceGuid.PcdCpuDxeProduceDebugSupport

   gArmTokenSpaceGuid.PcdRelocateVectorTable

+  gArmTokenSpaceGuid.PcdDebuggerExceptionSupport

   gArmTokenSpaceGuid.PcdEfiUncachedMemoryToStronglyOrdered

 

 [depex]

diff --git a/ArmPkg/Drivers/CpuDxe/Exception.c b/ArmPkg/Drivers/CpuDxe/Exception.c
index 21a4c035a9..7c59af7fef 100644
--- a/ArmPkg/Drivers/CpuDxe/Exception.c
+++ b/ArmPkg/Drivers/CpuDxe/Exception.c
@@ -162,8 +162,10 @@ InitializeExceptions (
         ASSERT_EFI_ERROR (Status);

       }

     

+    if (FeaturePcdGet(PcdDebuggerExceptionSupport) == TRUE) {

       // Save existing vector table, in case debugger is already hooked in

       CopyMem ((VOID *)gDebuggerExceptionHandlers, (VOID *)VectorBase, sizeof (gDebuggerExceptionHandlers));

+    }

     

       // Copy our assembly code into the page that contains the exception vectors. 

       CopyMem ((VOID *)VectorBase, (VOID *)ExceptionHandlersStart, Length);

@@ -178,7 +180,8 @@ InitializeExceptions (
       // Initialize the C entry points for interrupts

       //

       for (Index = 0; Index <= MAX_ARM_EXCEPTION; Index++) {

-        if ((gDebuggerExceptionHandlers[Index] == 0) || (gDebuggerExceptionHandlers[Index] == (VOID *)(UINTN)0xEAFFFFFE)) {

+      if (!FeaturePcdGet(PcdDebuggerExceptionSupport) ||

+          (gDebuggerExceptionHandlers[Index] == 0) || (gDebuggerExceptionHandlers[Index] == (VOID *)(UINTN)0xEAFFFFFE)) {

           // Exception handler contains branch to vector location (jmp $) so no handler

           // NOTE: This code assumes vectors are ARM and not Thumb code

           Status = RegisterInterruptHandler (Index, NULL);