Ensure GDT for APs is under 4G, in order to secure that APs can safely use it to switch from real mode to protected mode, as well as from protected mode to long mode.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@10290 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 18 insertions, 1 deletions

diff --git a/EdkCompatibilityPkg/Compatibility/MpServicesOnFrameworkMpServicesThunk/MpServicesOnFrameworkMpServicesThunk.c b/EdkCompatibilityPkg/Compatibility/MpServicesOnFrameworkMpServicesThunk/MpServicesOnFrameworkMpServicesThunk.c
index 9005670bae..4d0918fa78 100644
--- a/EdkCompatibilityPkg/Compatibility/MpServicesOnFrameworkMpServicesThunk/MpServicesOnFrameworkMpServicesThunk.c
+++ b/EdkCompatibilityPkg/Compatibility/MpServicesOnFrameworkMpServicesThunk/MpServicesOnFrameworkMpServicesThunk.c
@@ -1444,6 +1444,8 @@ PrepareAPStartupVector (
 {

   MP_ASSEMBLY_ADDRESS_MAP   AddressMap;

   IA32_DESCRIPTOR           GdtrForBSP;

+  EFI_PHYSICAL_ADDRESS      GdtForAP;

+  EFI_STATUS                Status;

 

   //

   // Get the address map of startup code for AP,

@@ -1481,7 +1483,22 @@ PrepareAPStartupVector (
   mExchangeInfo->StackSize  = AP_STACK_SIZE;

 

   AsmReadGdtr (&GdtrForBSP);

-  mExchangeInfo->GdtrProfile.Base  = GdtrForBSP.Base;

+

+  //

+  // Allocate memory under 4G to hold GDT for APs

+  //

+  GdtForAP = 0xffffffff;

+  Status   = gBS->AllocatePages (

+                    AllocateMaxAddress,

+                    EfiBootServicesData,

+                    EFI_SIZE_TO_PAGES (GdtrForBSP.Limit + 1),

+                    &GdtForAP

+                    );

+  ASSERT_EFI_ERROR (Status);

+

+  CopyMem ((VOID *) (UINTN) GdtForAP, (VOID *) GdtrForBSP.Base, GdtrForBSP.Limit + 1);

+

+  mExchangeInfo->GdtrProfile.Base  = (UINTN) GdtForAP;

   mExchangeInfo->GdtrProfile.Limit = GdtrForBSP.Limit;

 

   mExchangeInfo->BufferStart = (UINT32) mStartupVector;