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* [PATCH v4 0/6] Add NULL pointer detection feature
@ 2017-10-09 14:17 Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 1/6] MdeModulePkg/MdeModulePkg.dec, .uni: Add NULL pointer detection PCD Jian J Wang
                   ` (6 more replies)
  0 siblings, 7 replies; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel

The mechanism behind is to trigger a page fault exception at address 0.
This can be made by disabling page 0 (0-4095) during page table setup.
So this feature can only be available on platform with paging enabled.

Once this feature is enabled, any code, like CSM, which has to access
memory in page 0 needs to enable this page temporarily in advance and
disable it afterwards.

PcdNullPointerDetectionPropertyMask is used to control and elaborate
the use cases. For example, BIT7 of this PCD must be set for Windows 7
boot on Qemu if BIT0 set; or boot will fail.

Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>

Jian J Wang (5):
  MdeModulePkg/DxeIpl: Implement NULL pointer detection
  MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for NULL pointer
    detection
  UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM
    code
  IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection
  OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM
    installing

Wang, Jian J (1):
  MdeModulePkg/MdeModulePkg.dec,.uni: Add NULL pointer detection PCD

 .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c       | 101 ++++++++++++++
 .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h       |   2 +
 .../Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf      |   2 +
 .../Csm/LegacyBiosDxe/LegacyBda.c                  |   4 +
 .../Csm/LegacyBiosDxe/LegacyBios.c                 | 152 +++++++++++++++++++++
 .../Csm/LegacyBiosDxe/LegacyBiosDxe.inf            |   2 +
 .../Csm/LegacyBiosDxe/LegacyBiosInterface.h        |  18 +++
 .../Csm/LegacyBiosDxe/LegacyBootSupport.c          |  23 +++-
 .../Csm/LegacyBiosDxe/LegacyPci.c                  |  17 ++-
 IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c  |  27 +++-
 MdeModulePkg/Core/Dxe/DxeMain.inf                  |   1 +
 MdeModulePkg/Core/Dxe/Mem/Page.c                   |   4 +-
 MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c      |  65 +++++++++
 MdeModulePkg/Core/DxeIplPeim/DxeIpl.h              |  25 ++++
 MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf            |   1 +
 MdeModulePkg/Core/DxeIplPeim/DxeLoad.c             |   1 +
 MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c    |  17 ++-
 MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c     |   4 +
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c   |  93 ++++++++++++-
 MdeModulePkg/MdeModulePkg.dec                      |  13 ++
 MdeModulePkg/MdeModulePkg.uni                      |  13 ++
 OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf              |   1 +
 OvmfPkg/QemuVideoDxe/VbeShim.c                     |  14 ++
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c           |  12 ++
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c              |  25 +++-
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf       |   1 +
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c            |  12 ++
 27 files changed, 628 insertions(+), 22 deletions(-)

-- 
2.14.1.windows.1



^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH v4 1/6] MdeModulePkg/MdeModulePkg.dec, .uni: Add NULL pointer detection PCD
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 2/6] MdeModulePkg/DxeIpl: Implement NULL pointer detection Jian J Wang
                   ` (5 subsequent siblings)
  6 siblings, 0 replies; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Wang, Jian J, Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney,
	Ayellet Wolman

From: "Wang, Jian J" <jian.j.wang@intel.com>

PCD PcdNullPointerDetectionPropertyMask is a bitmask used to control the
NULL address detection functionality in code for different phases.

If enabled, accessing NULL address in UEFI or SMM code can be caught
as a page fault exception.

    BIT0    - Enable NULL pointer detection for UEFI.
    BIT1    - Enable NULL pointer detection for SMM.
    BIT2..6 - Reserved for future uses.
    BIT7    - Disable NULL pointer detection just after EndOfDxe. This is a
              workaround for those unsolvable NULL access issues in
              OptionROM, boot loader, etc. It can also help to avoid
              unnecessary exception caused by legacy memory (0-4095) access
              after EndOfDxe, such as Windows 7 boot on Qemu.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 MdeModulePkg/MdeModulePkg.dec | 13 +++++++++++++
 MdeModulePkg/MdeModulePkg.uni | 13 +++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index a3c0633ee1..9248d10da8 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -867,6 +867,19 @@
   # @ValidList  0x80000006 | 0x03058002
   gEfiMdeModulePkgTokenSpaceGuid.PcdErrorCodeSetVariable|0x03058002|UINT32|0x30001040
 
+  ## Mask to control the NULL address detection in code for different phases.
+  #  If enabled, accessing NULL address in UEFI or SMM code can be caught.<BR><BR>
+  #    BIT0    - Enable NULL pointer detection for UEFI.<BR>
+  #    BIT1    - Enable NULL pointer detection for SMM.<BR>
+  #    BIT2..6 - Reserved for future uses.<BR>
+  #    BIT7    - Disable NULL pointer detection just after EndOfDxe. <BR>
+  #              This is a workaround for those unsolvable NULL access issues in
+  #              OptionROM, boot loader, etc. It can also help to avoid unnecessary
+  #              exception caused by legacy memory (0-4095) access after EndOfDxe,
+  #              such as Windows 7 boot on Qemu.<BR>
+  # @Prompt Enable NULL address detection.
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask|0x0|UINT8|0x30001050
+
 [PcdsFixedAtBuild, PcdsPatchableInModule]
   ## Dynamic type PCD can be registered callback function for Pcd setting action.
   #  PcdMaxPeiPcdCallBackNumberPerPcdEntry indicates the maximum number of callback function
diff --git a/MdeModulePkg/MdeModulePkg.uni b/MdeModulePkg/MdeModulePkg.uni
index d6015de75f..f8b31694ba 100644
--- a/MdeModulePkg/MdeModulePkg.uni
+++ b/MdeModulePkg/MdeModulePkg.uni
@@ -1127,3 +1127,16 @@
                                                                                                      "enabled on AMD processors supporting the Secure Encrypted Virtualization (SEV) feature.\n"
                                                                                                      "This mask should be applied when creating 1:1 virtual to physical mapping tables."
 
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdNullPointerDetectionPropertyMask_PROMPT  #language en-US "Enable NULL pointer detection"
+
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdNullPointerDetectionPropertyMask_HELP    #language en-US "Mask to control the NULL address detection in code for different phases.\n"
+                                                                                                       " If enabled, accessing NULL address in UEFI or SMM code can be caught.\n\n"
+                                                                                                       "   BIT0    - Enable NULL pointer detection for UEFI.\n"
+                                                                                                       "   BIT1    - Enable NULL pointer detection for SMM.\n"
+                                                                                                       "   BIT2..6 - Reserved for future uses.\n"
+                                                                                                       "   BIT7    - Disable NULL pointer detection just after EndOfDxe."
+                                                                                                       " This is a workaround for those unsolvable NULL access issues in"
+                                                                                                       " OptionROM, boot loader, etc. It can also help to avoid unnecessary"
+                                                                                                       " exception caused by legacy memory (0-4095) access after EndOfDxe,"
+                                                                                                       " such as Windows 7 boot on Qemu.\n"
+
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH v4 2/6] MdeModulePkg/DxeIpl: Implement NULL pointer detection
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 1/6] MdeModulePkg/MdeModulePkg.dec, .uni: Add NULL pointer detection PCD Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 3/6] MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for " Jian J Wang
                   ` (4 subsequent siblings)
  6 siblings, 0 replies; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney, Ayellet Wolman

> According to Start's feedback
>   a. Change function ClearLegacyMemory to ClearFirst4KPage
>   b. Call ClearFirst4KPage only when NULL detection is enabled
>   c. Move ClearFirst4KPage to X64/Ia32 related files

NULL pointer detection is done by making use of paging mechanism of CPU.
During page table setup, if enabled, the first 4-K page (0-4095) will be
marked as NOT PRESENT. Any code which unintentionally access memory between
0-4095 will trigger a Page Fault exception which warns users that there's
potential illegal code in BIOS.

This also means that legacy code which has to access memory between 0-4095
should be cautious to temporarily disable this feature before the access
and re-enable it afterwards; or disalbe this feature at all.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 MdeModulePkg/Core/DxeIplPeim/DxeIpl.h            | 25 +++++++
 MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf          |  1 +
 MdeModulePkg/Core/DxeIplPeim/DxeLoad.c           |  1 +
 MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c  | 17 ++++-
 MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c   |  4 +
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 93 ++++++++++++++++++++++--
 6 files changed, 131 insertions(+), 10 deletions(-)

diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.h b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.h
index 72d2532f50..ecf186667a 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.h
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.h
@@ -240,4 +240,29 @@ Decompress (
   OUT       UINTN                   *OutputSize
   );
 
+/**
+   Clear legacy memory located at the first 4K-page.
+
+   This function traverses the whole HOB list to check if memory from 0 to 4095
+   exists and has not been allocated, and then clear it if so.
+
+   @param HoStart         The start of HobList passed to DxeCore.
+
+**/
+VOID
+ClearFirst4KPage (
+  IN  VOID *HobStart
+  );
+
+/**
+   Return configure status of NULL pointer detection feature
+
+   @return TRUE   NULL pointer detection feature is enabled
+   @return FALSE  NULL pointer detection feature is disabled
+**/
+BOOLEAN
+IsNullDetectionEnabled (
+  VOID
+  );
+
 #endif
diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
index c54afe4aa6..9d0e76a293 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
@@ -115,6 +115,7 @@
 [Pcd.IA32,Pcd.X64]
   gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable                      ## SOMETIMES_CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask    ## CONSUMES
 
 [Pcd.IA32,Pcd.X64,Pcd.ARM,Pcd.AARCH64]
   gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack               ## SOMETIMES_CONSUMES
diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeLoad.c b/MdeModulePkg/Core/DxeIplPeim/DxeLoad.c
index 50b5440d15..1f626a9e86 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeLoad.c
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeLoad.c
@@ -825,3 +825,4 @@ UpdateStackHob (
     Hob.Raw = GET_NEXT_HOB (Hob);
   }
 }
+
diff --git a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
index 1957326caf..96f5718444 100644
--- a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
@@ -123,7 +123,9 @@ Create4GPageTablesIa32Pae (
     PageDirectoryPointerEntry->Bits.Present = 1;
 
     for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PhysicalAddress += SIZE_2MB) {
-      if ((PhysicalAddress < StackBase + StackSize) && ((PhysicalAddress + SIZE_2MB) > StackBase)) {
+      if ((IsNullDetectionEnabled () && PhysicalAddress == 0)
+          || ((PhysicalAddress < StackBase + StackSize)
+              && ((PhysicalAddress + SIZE_2MB) > StackBase))) {
         //
         // Need to split this 2M page that covers stack range.
         //
@@ -240,6 +242,10 @@ HandOffToDxeCore (
   EFI_PEI_VECTOR_HANDOFF_INFO_PPI *VectorHandoffInfoPpi;
   BOOLEAN                   BuildPageTablesIa32Pae;
 
+  if (IsNullDetectionEnabled ()) {
+    ClearFirst4KPage (HobList.Raw);
+  }
+
   Status = PeiServicesAllocatePages (EfiBootServicesData, EFI_SIZE_TO_PAGES (STACK_SIZE), &BaseOfStack);
   ASSERT_EFI_ERROR (Status);
 
@@ -379,10 +385,15 @@ HandOffToDxeCore (
     TopOfStack = (EFI_PHYSICAL_ADDRESS) (UINTN) ALIGN_POINTER (TopOfStack, CPU_STACK_ALIGNMENT);
 
     PageTables = 0;
-    BuildPageTablesIa32Pae = (BOOLEAN) (PcdGetBool (PcdSetNxForStack) && IsIa32PaeSupport () && IsExecuteDisableBitAvailable ());
+    BuildPageTablesIa32Pae = (BOOLEAN) (IsIa32PaeSupport () &&
+                                        (IsNullDetectionEnabled () ||
+                                         (PcdGetBool (PcdSetNxForStack) &&
+                                          IsExecuteDisableBitAvailable ())));
     if (BuildPageTablesIa32Pae) {
       PageTables = Create4GPageTablesIa32Pae (BaseOfStack, STACK_SIZE);
-      EnableExecuteDisableBit ();
+      if (IsExecuteDisableBitAvailable ()) {
+        EnableExecuteDisableBit();
+      }
     }
 
     //
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
index 6488880eab..f613221b81 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
@@ -42,6 +42,10 @@ HandOffToDxeCore (
   EFI_VECTOR_HANDOFF_INFO         *VectorInfo;
   EFI_PEI_VECTOR_HANDOFF_INFO_PPI *VectorHandoffInfoPpi;
 
+  if (IsNullDetectionEnabled ()) {
+    ClearFirst4KPage (HobList.Raw);
+  }
+
   //
   // Get Vector Hand-off Info PPI and build Guided HOB
   //
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 48150be4e1..a10dea25fd 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -31,6 +31,68 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include "DxeIpl.h"
 #include "VirtualMemory.h"
 
+/**
+   Clear legacy memory located at the first 4K-page, if available.
+
+   This function traverses the whole HOB list to check if memory from 0 to 4095
+   exists and has not been allocated, and then clear it if so.
+
+   @param HoStart                   The start of HobList passed to DxeCore.
+
+**/
+VOID
+ClearFirst4KPage (
+  IN  VOID *HobStart
+  )
+{
+  EFI_PEI_HOB_POINTERS          RscHob;
+  EFI_PEI_HOB_POINTERS          MemHob;
+  BOOLEAN                       DoClear;
+
+  RscHob.Raw = HobStart;
+  MemHob.Raw = HobStart;
+  DoClear = FALSE;
+
+  //
+  // Check if page 0 exists and free
+  //
+  while ((RscHob.Raw = GetNextHob (EFI_HOB_TYPE_RESOURCE_DESCRIPTOR,
+                                   RscHob.Raw)) != NULL) {
+    if (RscHob.ResourceDescriptor->ResourceType == EFI_RESOURCE_SYSTEM_MEMORY &&
+        RscHob.ResourceDescriptor->PhysicalStart == 0) {
+      DoClear = TRUE;
+      //
+      // Make sure memory at 0-4095 has not been allocated.
+      //
+      while ((MemHob.Raw = GetNextHob (EFI_HOB_TYPE_MEMORY_ALLOCATION,
+                                       MemHob.Raw)) != NULL) {
+        if (MemHob.MemoryAllocation->AllocDescriptor.MemoryBaseAddress
+            < EFI_PAGE_SIZE) {
+          DoClear = FALSE;
+          break;
+        }
+        MemHob.Raw = GET_NEXT_HOB (MemHob);
+      }
+      break;
+    }
+    RscHob.Raw = GET_NEXT_HOB (RscHob);
+  }
+
+  if (DoClear) {
+    DEBUG ((DEBUG_INFO, "Clearing first 4K-page!\r\n"));
+    SetMem (NULL, EFI_PAGE_SIZE, 0);
+  }
+
+  return;
+}
+
+BOOLEAN
+IsNullDetectionEnabled (
+  VOID
+  )
+{
+  return ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) != 0);
+}
 
 /**
   Enable Execute Disable Bit.
@@ -90,8 +152,16 @@ Split2MPageTo4K (
     //
     PageTableEntry->Uint64 = (UINT64) PhysicalAddress4K | AddressEncMask;
     PageTableEntry->Bits.ReadWrite = 1;
-    PageTableEntry->Bits.Present = 1;
-    if ((PhysicalAddress4K >= StackBase) && (PhysicalAddress4K < StackBase + StackSize)) {
+
+    if (IsNullDetectionEnabled () && PhysicalAddress4K == 0) {
+      PageTableEntry->Bits.Present = 0;
+    } else {
+      PageTableEntry->Bits.Present = 1;
+    }
+
+    if (PcdGetBool (PcdSetNxForStack)
+        && (PhysicalAddress4K >= StackBase)
+        && (PhysicalAddress4K < StackBase + StackSize)) {
       //
       // Set Nx bit for stack.
       //
@@ -137,9 +207,12 @@ Split1GPageTo2M (
 
   PhysicalAddress2M = PhysicalAddress;
   for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PhysicalAddress2M += SIZE_2MB) {
-    if ((PhysicalAddress2M < StackBase + StackSize) && ((PhysicalAddress2M + SIZE_2MB) > StackBase)) {
+    if ((IsNullDetectionEnabled () && PhysicalAddress2M == 0)
+        || (PcdGetBool (PcdSetNxForStack)
+            && (PhysicalAddress2M < StackBase + StackSize)
+            && ((PhysicalAddress2M + SIZE_2MB) > StackBase))) {
       //
-      // Need to split this 2M page that covers stack range.
+      // Need to split this 2M page that covers NULL or stack range.
       //
       Split2MPageTo4K (PhysicalAddress2M, (UINT64 *) PageDirectoryEntry, StackBase, StackSize);
     } else {
@@ -279,7 +352,10 @@ CreateIdentityMappingPageTables (
       PageDirectory1GEntry = (VOID *) PageDirectoryPointerEntry;
     
       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectory1GEntry++, PageAddress += SIZE_1GB) {
-        if (PcdGetBool (PcdSetNxForStack) && (PageAddress < StackBase + StackSize) && ((PageAddress + SIZE_1GB) > StackBase)) {
+        if ((IsNullDetectionEnabled () && PageAddress == 0)
+            || (PcdGetBool (PcdSetNxForStack)
+                && (PageAddress < StackBase + StackSize)
+                && ((PageAddress + SIZE_1GB) > StackBase))) {
           Split1GPageTo2M (PageAddress, (UINT64 *) PageDirectory1GEntry, StackBase, StackSize);
         } else {
           //
@@ -308,9 +384,12 @@ CreateIdentityMappingPageTables (
         PageDirectoryPointerEntry->Bits.Present = 1;
 
         for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += SIZE_2MB) {
-          if (PcdGetBool (PcdSetNxForStack) && (PageAddress < StackBase + StackSize) && ((PageAddress + SIZE_2MB) > StackBase)) {
+          if ((IsNullDetectionEnabled () && PageAddress == 0)
+              || (PcdGetBool (PcdSetNxForStack)
+                  && (PageAddress < StackBase + StackSize)
+                  && ((PageAddress + SIZE_2MB) > StackBase))) {
             //
-            // Need to split this 2M page that covers stack range.
+            // Need to split this 2M page that covers NULL or stack range.
             //
             Split2MPageTo4K (PageAddress, (UINT64 *) PageDirectoryEntry, StackBase, StackSize);
           } else {
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH v4 3/6] MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for NULL pointer detection
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 1/6] MdeModulePkg/MdeModulePkg.dec, .uni: Add NULL pointer detection PCD Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 2/6] MdeModulePkg/DxeIpl: Implement NULL pointer detection Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 4/6] UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM code Jian J Wang
                   ` (3 subsequent siblings)
  6 siblings, 0 replies; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney, Ayellet Wolman

> According to Star's feedback, use GCD service instead of CPU arch
> protocol to change page attributes

One of issue caused by enabling NULL pointer detection is that some PCI
device OptionROM, binary drivers and binary OS boot loaders may have NULL
pointer access bugs, which will prevent BIOS from booting and is almost
impossible to fix. BIT7 of PCD PcdNullPointerDetectionPropertyMask is used
as a workaround to indicate BIOS to disable NULL pointer detection right
after event gEfiEndOfDxeEventGroupGuid, and then let boot continue.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 MdeModulePkg/Core/Dxe/DxeMain.inf             |  1 +
 MdeModulePkg/Core/Dxe/Mem/Page.c              |  4 +-
 MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 65 +++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Core/Dxe/DxeMain.inf b/MdeModulePkg/Core/Dxe/DxeMain.inf
index 30d5984f7c..0a161ffd71 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain.inf
+++ b/MdeModulePkg/Core/Dxe/DxeMain.inf
@@ -192,6 +192,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdPropertiesTableEnable                   ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdImageProtectionPolicy                   ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdDxeNxMemoryProtectionPolicy             ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask        ## CONSUMES
 
 # [Hob]
 # RESOURCE_DESCRIPTOR   ## CONSUMES
diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem/Page.c
index a142c79ee2..0468df3171 100644
--- a/MdeModulePkg/Core/Dxe/Mem/Page.c
+++ b/MdeModulePkg/Core/Dxe/Mem/Page.c
@@ -188,7 +188,9 @@ CoreAddRange (
   // used for other purposes.
   //  
   if (Type == EfiConventionalMemory && Start == 0 && (End >= EFI_PAGE_SIZE - 1)) {
-    SetMem ((VOID *)(UINTN)Start, EFI_PAGE_SIZE, 0);
+    if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+      SetMem ((VOID *)(UINTN)Start, EFI_PAGE_SIZE, 0);
+    }
   }
   
   //
diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
index a73c4ccd64..0fa89e4437 100644
--- a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
+++ b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
@@ -995,6 +995,53 @@ MemoryProtectionExitBootServicesCallback (
   }
 }
 
+/**
+  Disable NULL pointer detection after EndOfDxe. This is a workaround resort in
+  order to skip unfixable NULL pointer access issues detected in OptionROM or
+  boot loaders.
+
+  @param[in]  Event     The Event this notify function registered to.
+  @param[in]  Context   Pointer to the context data registered to the Event.
+**/
+VOID
+EFIAPI
+DisableNullDetectionAtTheEndOfDxe (
+  EFI_EVENT                               Event,
+  VOID                                    *Context
+  )
+{
+  EFI_STATUS                        Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR   Desc;
+
+  DEBUG ((DEBUG_INFO, "DisableNullDetectionAtTheEndOfDxe(): start\r\n"));
+  //
+  // Disable NULL pointer detection by enabling first 4K page
+  //
+  Status = CoreGetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Status = CoreSetMemorySpaceCapabilities (
+              0,
+              EFI_PAGE_SIZE,
+              Desc.Capabilities | EFI_MEMORY_RP
+              );
+    ASSERT_EFI_ERROR (Status);
+  }
+
+  Status = CoreSetMemorySpaceAttributes (
+            0,
+            EFI_PAGE_SIZE,
+            Desc.Attributes & ~EFI_MEMORY_RP
+            );
+  ASSERT_EFI_ERROR (Status);
+
+  CoreCloseEvent (Event);
+  DEBUG ((DEBUG_INFO, "DisableNullDetectionAtTheEndOfDxe(): end\r\n"));
+
+  return;
+}
+
 /**
   Initialize Memory Protection support.
 **/
@@ -1006,6 +1053,7 @@ CoreInitializeMemoryProtection (
 {
   EFI_STATUS  Status;
   EFI_EVENT   Event;
+  EFI_EVENT   EndOfDxeEvent;
   VOID        *Registration;
 
   mImageProtectionPolicy = PcdGet32(PcdImageProtectionPolicy);
@@ -1044,6 +1092,23 @@ CoreInitializeMemoryProtection (
                );
     ASSERT_EFI_ERROR(Status);
   }
+
+  //
+  // Register a callback to disable NULL pointer detection at EndOfDxe
+  //
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7))
+       == (BIT0|BIT7)) {
+    Status = CoreCreateEventEx (
+                    EVT_NOTIFY_SIGNAL,
+                    TPL_NOTIFY,
+                    DisableNullDetectionAtTheEndOfDxe,
+                    NULL,
+                    &gEfiEndOfDxeEventGroupGuid,
+                    &EndOfDxeEvent
+                    );
+    ASSERT_EFI_ERROR (Status);
+  }
+
   return ;
 }
 
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH v4 4/6] UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM code
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
                   ` (2 preceding siblings ...)
  2017-10-09 14:17 ` [PATCH v4 3/6] MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for " Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-09 14:17 ` [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection Jian J Wang
                   ` (2 subsequent siblings)
  6 siblings, 0 replies; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney, Ayellet Wolman

The mechanism behind is the same as NULL pointer detection enabled in EDK-II
core. SMM has its own page table and we have to disable page 0 again in SMM
mode.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c     | 12 ++++++++++++
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c        | 25 ++++++++++++++++++++++++-
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf |  1 +
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c      | 12 ++++++++++++
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
index f295c2ebf2..641a1d69a2 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
@@ -155,6 +155,18 @@ SmiPFHandler (
     }
   }
 
+  //
+  // If NULL pointer was just accessed
+  //
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT1) != 0 &&
+      (PFAddress < EFI_PAGE_SIZE)) {
+    DEBUG ((DEBUG_ERROR, "!!! NULL pointer access !!!\n"));
+    DEBUG_CODE (
+      DumpModuleInfoByIp ((UINTN)SystemContext.SystemContextIa32->Eip);
+    );
+    CpuDeadLoop ();
+  }
+
   if (FeaturePcdGet (PcdCpuSmmProfileEnable)) {
     SmmProfilePFHandler (
       SystemContext.SystemContextIa32->Eip,
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index f086b97c30..0d3223d714 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -855,10 +855,10 @@ Gen4GPageTable (
     Pte[Index] = (Index << 21) | mAddressEncMask | IA32_PG_PS | PAGE_ATTRIBUTE_BITS;
   }
 
+  Pdpte = (UINT64*)PageTable;
   if (FeaturePcdGet (PcdCpuSmmStackGuard)) {
     Pages = (UINTN)PageTable + EFI_PAGES_TO_SIZE (5);
     GuardPage = mSmmStackArrayBase + EFI_PAGE_SIZE;
-    Pdpte = (UINT64*)PageTable;
     for (PageIndex = Low2MBoundary; PageIndex <= High2MBoundary; PageIndex += SIZE_2MB) {
       Pte = (UINT64*)(UINTN)(Pdpte[BitFieldRead32 ((UINT32)PageIndex, 30, 31)] & ~mAddressEncMask & ~(EFI_PAGE_SIZE - 1));
       Pte[BitFieldRead32 ((UINT32)PageIndex, 21, 29)] = (UINT64)Pages | mAddressEncMask | PAGE_ATTRIBUTE_BITS;
@@ -886,6 +886,29 @@ Gen4GPageTable (
     }
   }
 
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT1) != 0) {
+    Pte = (UINT64*)(UINTN)(Pdpte[0] & ~mAddressEncMask & ~(EFI_PAGE_SIZE - 1));
+    if ((Pte[0] & IA32_PG_PS) == 0) {
+      // 4K-page entries are already mapped. Just hide the first one anyway.
+      Pte = (UINT64*)(UINTN)(Pte[0] & ~mAddressEncMask & ~(EFI_PAGE_SIZE - 1));
+      Pte[0] &= ~IA32_PG_P; // Hide page 0
+    } else {
+      // Create 4K-page entries
+      Pages = (UINTN)AllocatePageTableMemory (1);
+      ASSERT (Pages != 0);
+
+      Pte[0] = (UINT64)(Pages | mAddressEncMask | PAGE_ATTRIBUTE_BITS);
+
+      Pte = (UINT64*)Pages;
+      PageAddress = 0;
+      Pte[0] = PageAddress | mAddressEncMask; // Hide page 0 but present left
+      for (Index = 1; Index < EFI_PAGE_SIZE / sizeof (*Pte); Index++) {
+        PageAddress += EFI_PAGE_SIZE;
+        Pte[Index] = PageAddress | mAddressEncMask | PAGE_ATTRIBUTE_BITS;
+      }
+    }
+  }
+
   return (UINT32)(UINTN)PageTable;
 }
 
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
index 099792e6ce..31cb215342 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
@@ -159,6 +159,7 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStaticPageTable               ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable                   ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask    ## CONSUMES
 
 [Depex]
   gEfiMpServiceProtocolGuid
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
index 3dde80f9ba..f3791ce897 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
@@ -872,6 +872,18 @@ SmiPFHandler (
     }
   }
 
+  //
+  // If NULL pointer was just accessed
+  //
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT1) != 0 &&
+      (PFAddress < EFI_PAGE_SIZE)) {
+    DEBUG ((DEBUG_ERROR, "!!! NULL pointer access !!!\n"));
+    DEBUG_CODE (
+      DumpModuleInfoByIp ((UINTN)SystemContext.SystemContextX64->Rip);
+    );
+    CpuDeadLoop ();
+  }
+
   if (FeaturePcdGet (PcdCpuSmmProfileEnable)) {
     SmmProfilePFHandler (
       SystemContext.SystemContextX64->Rip,
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
                   ` (3 preceding siblings ...)
  2017-10-09 14:17 ` [PATCH v4 4/6] UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM code Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-11 21:29   ` Laszlo Ersek
  2017-10-09 14:17 ` [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing Jian J Wang
  2017-10-11  0:52 ` [PATCH v4 0/6] Add NULL pointer detection feature Wang, Jian J
  6 siblings, 1 reply; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney, Ayellet Wolman

Legacy has to access interrupt vector, BDA, etc. located in memory between
0-4095. To allow as much code as possible to be monitored by NULL pointer
detection, we add code to temporarily disable this feature right before
those memory access and enable it again afterwards.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c       | 101 ++++++++++++++
 .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h       |   2 +
 .../Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf      |   2 +
 .../Csm/LegacyBiosDxe/LegacyBda.c                  |   4 +
 .../Csm/LegacyBiosDxe/LegacyBios.c                 | 152 +++++++++++++++++++++
 .../Csm/LegacyBiosDxe/LegacyBiosDxe.inf            |   2 +
 .../Csm/LegacyBiosDxe/LegacyBiosInterface.h        |  18 +++
 .../Csm/LegacyBiosDxe/LegacyBootSupport.c          |  23 +++-
 .../Csm/LegacyBiosDxe/LegacyPci.c                  |  17 ++-
 IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c  |  27 +++-
 10 files changed, 338 insertions(+), 10 deletions(-)

diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
index 7308523ad8..d2224a20aa 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c
@@ -1732,6 +1732,98 @@ CheckKeyboardConnect (
   }
 }
 
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already cleared.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) != 0) {
+    Desc.Attributes &= ~EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  } else {
+    DEBUG ((DEBUG_WARN, "!!! Page 0 is supposed to be disabled !!!\r\n"));
+  }
+}
+
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already set.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) == 0) {
+    Desc.Attributes |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  }
+}
+
 /**
   Timer event handler: read a series of key stroke from 8042
   and put them into memory key buffer. 
@@ -1839,6 +1931,11 @@ BiosKeyboardTimerHandler (
   //   0 Right Shift pressed
 
 
+  //
+  // Disable NULL pointer detection temporarily
+  //
+  DisableNullDetection ();
+
   //
   // Clear the CTRL and ALT BDA flag
   //
@@ -1916,6 +2013,10 @@ BiosKeyboardTimerHandler (
   KbFlag1 &= ~0x0C;                      
   *((UINT8 *) (UINTN) 0x417) = KbFlag1; 
 
+  //
+  // Restore NULL pointer detection
+  //
+  EnableNullDetection ();
   
   //
   // Output EFI input key and shift/toggle state
diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
index 0bf28ea140..c64ec0095e 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h
@@ -18,6 +18,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 
 #include <FrameworkDxe.h>
+#include <Pi/PiDxeCis.h>
 
 #include <Guid/StatusCodeDataTypeId.h>
 #include <Protocol/SimpleTextIn.h>
@@ -33,6 +34,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/ReportStatusCodeLib.h>
 #include <Library/UefiDriverEntryPoint.h>
 #include <Library/UefiBootServicesTableLib.h>
+#include <Library/DxeServicesTableLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/BaseLib.h>
 #include <Library/PcdLib.h>
diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
index 4d4536466c..596f4ced44 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf
@@ -60,6 +60,7 @@
   DebugLib
   BaseLib
   PcdLib
+  DxeServicesTableLib
 
 [Protocols]
   gEfiIsaIoProtocolGuid                         ## TO_START
@@ -73,6 +74,7 @@
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdFastPS2Detection                  ## SOMETIMES_CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask  ## CONSUMES
 
 [UserExtensions.TianoCore."ExtraFiles"]
   KeyboardDxeExtra.uni
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
index c45d5d4c3e..c6670febee 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBda.c
@@ -34,6 +34,8 @@ LegacyBiosInitBda (
   BDA_STRUC *Bda;
   UINT8     *Ebda;
 
+  DisableNullDetection ();
+
   Bda   = (BDA_STRUC *) ((UINTN) 0x400);
   Ebda  = (UINT8 *) ((UINTN) 0x9fc00);
 
@@ -62,5 +64,7 @@ LegacyBiosInitBda (
 
   *Ebda               = 0x01;
 
+  EnableNullDetection ();
+
   return EFI_SUCCESS;
 }
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
index 3ead2d9828..3176a989f6 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBios.c
@@ -40,6 +40,7 @@ VOID                  *mRuntimeSmbiosEntryPoint = NULL;
 EFI_PHYSICAL_ADDRESS  mReserveSmbiosEntryPoint = 0;
 EFI_PHYSICAL_ADDRESS  mStructureTableAddress   = 0;
 UINTN                 mStructureTablePages     = 0;
+BOOLEAN               mEndOfDxe                = FALSE;
 
 /**
   Do an AllocatePages () of type AllocateMaxAddress for EfiBootServicesCode
@@ -765,6 +766,135 @@ InstallSmbiosEventCallback (
   }
 }
 
+/**
+  Callback function to toggle EndOfDxe status. NULL pointer detection needs
+  this status to decide if it's necessary to change attributes of page 0.
+
+  @param  Event            Event whose notification function is being invoked.
+  @param  Context          The pointer to the notification function's context,
+                           which is implementation-dependent.
+
+**/
+VOID
+EFIAPI
+ToggleEndOfDxeStatus (
+  IN EFI_EVENT                Event,
+  IN VOID                     *Context
+  )
+{
+  mEndOfDxe = TRUE;
+  return;
+}
+
+//
+// Legacy BIOS needs to access memory between 0-4095, which will cause page
+// fault exception if NULL pointer detection mechanism is enabled. Following
+// functions can be used to disable/enable NULL pointer detection before/after
+// accessing those memory.
+//
+
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if (((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0)
+      ||
+      ((mEndOfDxe == TRUE)  &&
+       ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT7|BIT0))
+        == (BIT7|BIT0)))
+     ) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already set.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) == 0) {
+    Desc.Attributes |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  }
+}
+
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  )
+{
+  EFI_STATUS                            Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc;
+
+  if (((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0)
+      ||
+      ((mEndOfDxe == TRUE)  &&
+       ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT7|BIT0))
+        == (BIT7|BIT0)))
+     ) {
+    return;
+  }
+
+  //
+  // Check current capabilities and attributes
+  //
+  Status = gDS->GetMemorySpaceDescriptor (0, &Desc);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Try to add EFI_MEMORY_RP support if necessary
+  //
+  if ((Desc.Capabilities & EFI_MEMORY_RP) == 0) {
+    Desc.Capabilities |= EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceCapabilities (0, EFI_PAGES_TO_SIZE(1),
+                                              Desc.Capabilities);
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return;
+    }
+  }
+
+  //
+  // Don't bother if EFI_MEMORY_RP is already cleared.
+  //
+  if ((Desc.Attributes & EFI_MEMORY_RP) != 0) {
+    Desc.Attributes &= ~EFI_MEMORY_RP;
+    Status = gDS->SetMemorySpaceAttributes (0, EFI_PAGES_TO_SIZE(1),
+                                            Desc.Attributes);
+    ASSERT_EFI_ERROR (Status);
+  } else {
+    DEBUG ((DEBUG_WARN, "!!! Page 0 is supposed to be disabled !!!\r\n"));
+  }
+}
+
 /**
   Install Driver to produce Legacy BIOS protocol.
 
@@ -802,6 +932,7 @@ LegacyBiosInstall (
   UINT64                             Length;
   UINT8                              *SecureBoot;
   EFI_EVENT                          InstallSmbiosEvent;
+  EFI_EVENT                          EndOfDxeEvent;
 
   //
   // Load this driver's image to memory
@@ -964,8 +1095,10 @@ LegacyBiosInstall (
   // Initialize region from 0x0000 to 4k. This initializes interrupt vector
   // range.
   //
+  DisableNullDetection ();
   gBS->SetMem ((VOID *) ClearPtr, 0x400, INITIAL_VALUE_BELOW_1K);
   ZeroMem ((VOID *) ((UINTN)ClearPtr + 0x400), 0xC00);
+  EnableNullDetection ();
 
   //
   // Allocate pages for OPROM usage
@@ -1104,12 +1237,17 @@ LegacyBiosInstall (
   //
   // Save Unexpected interrupt vector so can restore it just prior to boot
   //
+  DisableNullDetection ();
+
   BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
   Private->BiosUnexpectedInt = BaseVectorMaster[0];
   IntRedirCode = (UINT32) (UINTN) Private->IntThunk->InterruptRedirectionCode;
   for (Index = 0; Index < 8; Index++) {
     BaseVectorMaster[Index] = (EFI_SEGMENT (IntRedirCode + Index * 4) << 16) | EFI_OFFSET (IntRedirCode + Index * 4);
   }
+
+  EnableNullDetection ();
+
   //
   // Save EFI value
   //
@@ -1133,6 +1271,20 @@ LegacyBiosInstall (
                   );
   ASSERT_EFI_ERROR (Status);  
 
+  //
+  // Create callback to update status of EndOfDxe, which is needed by NULL
+  // pointer detection
+  //
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_NOTIFY,
+                  ToggleEndOfDxeStatus,
+                  NULL,
+                  &gEfiEndOfDxeEventGroupGuid,
+                  &EndOfDxeEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
+
   //
   // Make a new handle and install the protocol
   //
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
index 48473a0713..6efc7f36ae 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosDxe.inf
@@ -108,6 +108,7 @@
   gEfiDiskInfoIdeInterfaceGuid                  ## SOMETIMES_CONSUMES ##GUID #Used in LegacyBiosBuildIdeData() to assure device is a disk
   gEfiSmbiosTableGuid                           ## SOMETIMES_CONSUMES ##SystemTable
   gEfiLegacyBiosGuid                            ## SOMETIMES_CONSUMES ##GUID #Used in LegacyBiosInstallVgaRom() to locate handle buffer
+  gEfiEndOfDxeEventGroupGuid                    ## CONSUMES
 
 [Guids.IA32]
   gEfiAcpi20TableGuid                           ## SOMETIMES_CONSUMES ##SystemTable
@@ -147,6 +148,7 @@
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdHighPmmMemorySize            ## CONSUMES
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdOpromReservedMemoryBase      ## CONSUMES
   gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdOpromReservedMemorySize      ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask        ## CONSUMES
 
 [Depex]
   gEfiLegacyRegion2ProtocolGuid AND gEfiLegacyInterruptProtocolGuid AND gEfiLegacyBiosPlatformProtocolGuid AND gEfiLegacy8259ProtocolGuid AND gEfiGenericMemTestProtocolGuid AND gEfiCpuArchProtocolGuid AND gEfiTimerArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
index fe9dd7463a..20dfef3fec 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBiosInterface.h
@@ -509,6 +509,8 @@ extern BBS_TABLE           *mBbsTable;
 
 extern EFI_GENERIC_MEMORY_TEST_PROTOCOL *gGenMemoryTest;
 
+extern BOOLEAN mEndOfDxe;
+
 #define PORT_70 0x70
 #define PORT_71 0x71
 
@@ -1542,4 +1544,20 @@ LegacyBiosInstallVgaRom (
   IN  LEGACY_BIOS_INSTANCE            *Private
   );
 
+/**
+   Enable NULL pointer detection
+*/
+VOID
+EnableNullDetection (
+  VOID
+  );
+
+/**
+   Disable NULL pointer detection
+*/
+VOID
+DisableNullDetection (
+  VOID
+  );
+
 #endif
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
index 1e098b3726..c2ac69ce69 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
@@ -1073,8 +1073,10 @@ GenericLegacyBoot (
   // Use 182/10 to avoid floating point math.
   //
   LocalTime = (LocalTime * 182) / 10;
+  DisableNullDetection ();
   BdaPtr    = (UINT32 *) (UINTN)0x46C;
   *BdaPtr   = LocalTime;
+  EnableNullDetection ();
 
   //
   // Shadow PCI ROMs. We must do this near the end since this will kick
@@ -1320,6 +1322,7 @@ GenericLegacyBoot (
     //          set of TIANO vectors) or takes it over.
     //
     //
+    DisableNullDetection ();
     BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
     for (Index = 0; Index < 8; Index++) {
       Private->ThunkSavedInt[Index] = BaseVectorMaster[Index];
@@ -1327,6 +1330,7 @@ GenericLegacyBoot (
         BaseVectorMaster[Index] = (UINT32) (Private->BiosUnexpectedInt);
       }
     }
+    EnableNullDetection ();
 
     ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));
     Regs.X.AX = Legacy16Boot;
@@ -1340,10 +1344,12 @@ GenericLegacyBoot (
       0
       );
 
+    DisableNullDetection ();
     BaseVectorMaster = (UINT32 *) (sizeof (UINT32) * PROTECTED_MODE_BASE_VECTOR_MASTER);
     for (Index = 0; Index < 8; Index++) {
       BaseVectorMaster[Index] = Private->ThunkSavedInt[Index];
     }
+    EnableNullDetection ();
   }
   Private->LegacyBootEntered = TRUE;
   if ((mBootMode == BOOT_LEGACY_OS) || (mBootMode == BOOT_UNCONVENTIONAL_DEVICE)) {
@@ -1731,9 +1737,11 @@ LegacyBiosBuildE820 (
   //
   // First entry is 0 to (640k - EBDA)
   //
+  DisableNullDetection ();
   E820Table[0].BaseAddr  = 0;
   E820Table[0].Length    = (UINT64) ((*(UINT16 *) (UINTN)0x40E) << 4);
   E820Table[0].Type      = EfiAcpiAddressRangeMemory;
+  EnableNullDetection ();
 
   //
   // Second entry is (640k - EBDA) to 640k
@@ -1967,6 +1975,8 @@ LegacyBiosCompleteBdaBeforeBoot (
   UINT16                      MachineConfig;
   DEVICE_PRODUCER_DATA_HEADER *SioPtr;
 
+  DisableNullDetection ();
+
   Bda           = (BDA_STRUC *) ((UINTN) 0x400);
   MachineConfig = 0;
 
@@ -2025,6 +2035,8 @@ LegacyBiosCompleteBdaBeforeBoot (
   MachineConfig       = (UINT16) (MachineConfig + 0x00 + 0x02 + (SioPtr->MousePresent * 0x04));
   Bda->MachineConfig  = MachineConfig;
 
+  EnableNullDetection ();
+
   return EFI_SUCCESS;
 }
 
@@ -2049,15 +2061,20 @@ LegacyBiosUpdateKeyboardLedStatus (
   UINT8                 LocalLeds;
   EFI_IA32_REGISTER_SET Regs;
 
-  Bda                 = (BDA_STRUC *) ((UINTN) 0x400);
-
   Private             = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
+
+  DisableNullDetection ();
+
+  Bda                 = (BDA_STRUC *) ((UINTN) 0x400);
   LocalLeds           = Leds;
   Bda->LedStatus      = (UINT8) ((Bda->LedStatus &~0x07) | LocalLeds);
   LocalLeds           = (UINT8) (LocalLeds << 4);
   Bda->ShiftStatus    = (UINT8) ((Bda->ShiftStatus &~0x70) | LocalLeds);
   LocalLeds           = (UINT8) (Leds & 0x20);
   Bda->KeyboardStatus = (UINT8) ((Bda->KeyboardStatus &~0x20) | LocalLeds);
+
+  EnableNullDetection ();
+
   //
   // Call into Legacy16 code to allow it to do any processing
   //
@@ -2102,7 +2119,9 @@ LegacyBiosCompleteStandardCmosBeforeBoot (
   //            to large capacity drives
   // CMOS 14 = BDA 40:10 plus bit 3(display enabled)
   //
+  DisableNullDetection ();
   Bda = (UINT8)(*((UINT8 *)((UINTN)0x410)) | BIT3);
+  EnableNullDetection ();
 
   //
   // Force display enabled
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
index 8ffdf0c1ff..d38cef3e33 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
@@ -2279,6 +2279,7 @@ LegacyBiosInstallRom (
   UINTN                 Function;
   EFI_IA32_REGISTER_SET Regs;
   UINT8                 VideoMode;
+  UINT8                 OldVideoMode;
   EFI_TIME              BootTime;
   UINT32                *BdaPtr;
   UINT32                LocalTime;
@@ -2299,6 +2300,7 @@ LegacyBiosInstallRom (
   Device          = 0;
   Function        = 0;
   VideoMode       = 0;
+  OldVideoMode    = 0;
   PhysicalAddress = 0;
   MaxRomAddr      = PcdGet32 (PcdEndOpromShadowAddress);
 
@@ -2401,6 +2403,8 @@ LegacyBiosInstallRom (
   // 2. BBS compliants drives will not change 40:75 until boot time.
   // 3. Onboard IDE controllers will change 40:75
   //
+  DisableNullDetection ();
+
   LocalDiskStart = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
   if ((Private->Disk4075 + 0x80) < LocalDiskStart) {
     //
@@ -2426,6 +2430,9 @@ LegacyBiosInstallRom (
     //
     VideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
   }
+
+  EnableNullDetection ();
+
   //
   // Notify the platform that we are about to scan the ROM
   //
@@ -2466,9 +2473,11 @@ LegacyBiosInstallRom (
   // Multiply result by 18.2 for number of ticks since midnight.
   // Use 182/10 to avoid floating point math.
   //
+  DisableNullDetection ();
   LocalTime = (LocalTime * 182) / 10;
   BdaPtr    = (UINT32 *) ((UINTN) 0x46C);
   *BdaPtr   = LocalTime;
+  EnableNullDetection ();
   
   //
   // Pass in handoff data
@@ -2564,7 +2573,11 @@ LegacyBiosInstallRom (
     //
     // Set mode settings since PrepareToScanRom may change mode
     //
-    if (VideoMode != *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE))) {
+    DisableNullDetection ();
+    OldVideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
+    EnableNullDetection ();
+
+    if (VideoMode != OldVideoMode) {
       //
       // The active video mode is changed, restore it to original mode.
       //
@@ -2604,7 +2617,9 @@ LegacyBiosInstallRom (
     }
   }
 
+  DisableNullDetection ();
   LocalDiskEnd = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
+  EnableNullDetection ();
   
   //
   // Allow platform to perform any required actions after the
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
index 3d9a8b9649..f42c13cd89 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
@@ -57,7 +57,11 @@ LegacyBiosInt86 (
   IN  EFI_IA32_REGISTER_SET         *Regs
   )
 {
-  UINT32  *VectorBase;
+  UINT16                Segment;
+  UINT16                Offset;
+  LEGACY_BIOS_INSTANCE  *Private;
+
+  Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
 
   Regs->X.Flags.Reserved1 = 1;
   Regs->X.Flags.Reserved2 = 0;
@@ -72,12 +76,15 @@ LegacyBiosInt86 (
   // The base address of legacy interrupt vector table is 0.
   // We use this base address to get the legacy interrupt handler.
   //
-  VectorBase              = 0;
+  DisableNullDetection ();
+  Segment               = (UINT16)(((UINT32 *)0)[BiosInt] >> 16);
+  Offset                = (UINT16)((UINT32 *)0)[BiosInt];
+  EnableNullDetection ();
   
   return InternalLegacyBiosFarCall (
            This,
-           (UINT16) ((VectorBase)[BiosInt] >> 16),
-           (UINT16) (VectorBase)[BiosInt],
+           Segment,
+           Offset,
            Regs,
            &Regs->X.Flags,
            sizeof (Regs->X.Flags)
@@ -293,9 +300,15 @@ InternalLegacyBiosFarCall (
       UINTN                 EbdaBaseAddress;
       UINTN                 ReservedEbdaBaseAddress;
 
-      EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
-      ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);
-      ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
+      //
+      // Skip this part of debug code if NULL pointer detection is enabled
+      //
+      if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
+        EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
+        ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP
+                                  - PcdGet32 (PcdEbdaReservedMemorySize);
+        ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
+      }
     }
   );
 
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
                   ` (4 preceding siblings ...)
  2017-10-09 14:17 ` [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection Jian J Wang
@ 2017-10-09 14:17 ` Jian J Wang
  2017-10-09 15:54   ` Laszlo Ersek
  2017-10-11  0:52 ` [PATCH v4 0/6] Add NULL pointer detection feature Wang, Jian J
  6 siblings, 1 reply; 15+ messages in thread
From: Jian J Wang @ 2017-10-09 14:17 UTC (permalink / raw)
  To: edk2-devel
  Cc: Star Zeng, Eric Dong, Jiewen Yao, Michael Kinney, Ayellet Wolman

QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
detection is enabled, this driver will fail to load. NULL pointer detection
bypassing code is added to prevent such problem during boot.

Please note that Windows 7 will try to access VBE SHIM during boot if it's
installed, and then cause boot failure. This can be fixed by setting BIT7
of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
after EndOfDxe. As far as we know, there's no other OSs has such issue.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
 OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
index 577e07b0a8..ff68c99e96 100644
--- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
+++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
@@ -77,3 +77,4 @@
 [Pcd]
   gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
+  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c b/OvmfPkg/QemuVideoDxe/VbeShim.c
index e45a08e887..8ba5522cde 100644
--- a/OvmfPkg/QemuVideoDxe/VbeShim.c
+++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
@@ -75,6 +75,20 @@ InstallVbeShim (
   UINTN                Printed;
   VBE_MODE_INFO        *VbeModeInfo;
 
+  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0) {
+    DEBUG ((
+      DEBUG_WARN,
+      "%a: page 0 protected, not installing VBE shim\n",
+      __FUNCTION__
+      ));
+    DEBUG ((
+      DEBUG_WARN,
+      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
+      __FUNCTION__
+      ));
+    return;
+  }
+
   Segment0 = 0x00000;
   SegmentC = 0xC0000;
   SegmentF = 0xF0000;
-- 
2.14.1.windows.1



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-09 14:17 ` [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing Jian J Wang
@ 2017-10-09 15:54   ` Laszlo Ersek
  2017-10-09 15:55     ` Laszlo Ersek
  0 siblings, 1 reply; 15+ messages in thread
From: Laszlo Ersek @ 2017-10-09 15:54 UTC (permalink / raw)
  To: Jian J Wang, edk2-devel
  Cc: Michael Kinney, Ayellet Wolman, Jiewen Yao, Eric Dong, Star Zeng

On 10/09/17 16:17, Jian J Wang wrote:
> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
> detection is enabled, this driver will fail to load. NULL pointer detection
> bypassing code is added to prevent such problem during boot.
> 
> Please note that Windows 7 will try to access VBE SHIM during boot if it's
> installed, and then cause boot failure. This can be fixed by setting BIT7
> of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
> after EndOfDxe. As far as we know, there's no other OSs has such issue.
> 
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Michael Kinney <michael.d.kinney@intel.com>
> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
>  OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> index 577e07b0a8..ff68c99e96 100644
> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> @@ -77,3 +77,4 @@
>  [Pcd]
>    gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c b/OvmfPkg/QemuVideoDxe/VbeShim.c
> index e45a08e887..8ba5522cde 100644
> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
> @@ -75,6 +75,20 @@ InstallVbeShim (
>    UINTN                Printed;
>    VBE_MODE_INFO        *VbeModeInfo;
>  
> +  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0) {
> +    DEBUG ((
> +      DEBUG_WARN,
> +      "%a: page 0 protected, not installing VBE shim\n",
> +      __FUNCTION__
> +      ));
> +    DEBUG ((
> +      DEBUG_WARN,
> +      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
> +      __FUNCTION__
> +      ));
> +    return;
> +  }
> +
>    Segment0 = 0x00000;
>    SegmentC = 0xC0000;
>    SegmentF = 0xF0000;
> 

If this patch is entirely identical to the previous version (v3), then
you should have please picked up the review tags from Jordan and myself,
the ones that you got for v3:

http://mid.mail-archive.com/150696711831.2454.16712170525103415248@jljusten-skl

http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-d03b330047cc@redhat.com

This way we can quickly filter out already reviewed patches, and avoid
re-reviewing when there are no changes.


Your cover letter v4 0/6 also does not summarize the changes relative to
v3; in the future please don't forget about that.

Thanks
Laszlo


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-09 15:54   ` Laszlo Ersek
@ 2017-10-09 15:55     ` Laszlo Ersek
  2017-10-10  1:50       ` Wang, Jian J
  0 siblings, 1 reply; 15+ messages in thread
From: Laszlo Ersek @ 2017-10-09 15:55 UTC (permalink / raw)
  To: Jian J Wang, edk2-devel
  Cc: Michael Kinney, Ayellet Wolman, Jiewen Yao, Eric Dong, Star Zeng

On 10/09/17 17:54, Laszlo Ersek wrote:
> On 10/09/17 16:17, Jian J Wang wrote:
>> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
>> detection is enabled, this driver will fail to load. NULL pointer detection
>> bypassing code is added to prevent such problem during boot.
>>
>> Please note that Windows 7 will try to access VBE SHIM during boot if it's
>> installed, and then cause boot failure. This can be fixed by setting BIT7
>> of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
>> after EndOfDxe. As far as we know, there's no other OSs has such issue.
>>
>> Cc: Star Zeng <star.zeng@intel.com>
>> Cc: Eric Dong <eric.dong@intel.com>
>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>> Cc: Michael Kinney <michael.d.kinney@intel.com>
>> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
>> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
>> ---
>>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
>>  OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
>>  2 files changed, 15 insertions(+)
>>
>> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>> index 577e07b0a8..ff68c99e96 100644
>> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>> @@ -77,3 +77,4 @@
>>  [Pcd]
>>    gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
>>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
>> +  gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
>> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c b/OvmfPkg/QemuVideoDxe/VbeShim.c
>> index e45a08e887..8ba5522cde 100644
>> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
>> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
>> @@ -75,6 +75,20 @@ InstallVbeShim (
>>    UINTN                Printed;
>>    VBE_MODE_INFO        *VbeModeInfo;
>>  
>> +  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0) {
>> +    DEBUG ((
>> +      DEBUG_WARN,
>> +      "%a: page 0 protected, not installing VBE shim\n",
>> +      __FUNCTION__
>> +      ));
>> +    DEBUG ((
>> +      DEBUG_WARN,
>> +      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
>> +      __FUNCTION__
>> +      ));
>> +    return;
>> +  }
>> +
>>    Segment0 = 0x00000;
>>    SegmentC = 0xC0000;
>>    SegmentF = 0xF0000;
>>
> 
> If this patch is entirely identical to the previous version (v3), then
> you should have please picked up the review tags from Jordan and myself,
> the ones that you got for v3:
> 
> http://mid.mail-archive.com/150696711831.2454.16712170525103415248@jljusten-skl
> 
> http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-d03b330047cc@redhat.com
> 
> This way we can quickly filter out already reviewed patches, and avoid
> re-reviewing when there are no changes.
> 
> 
> Your cover letter v4 0/6 also does not summarize the changes relative to
> v3; in the future please don't forget about that.

... personal CC's for OvmfPkg maintainers and reviewers are also missing
from this patch. Please check "Maintainers.txt" every time.

Thanks
Laszlo


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-09 15:55     ` Laszlo Ersek
@ 2017-10-10  1:50       ` Wang, Jian J
  2017-10-10  8:13         ` Laszlo Ersek
  0 siblings, 1 reply; 15+ messages in thread
From: Wang, Jian J @ 2017-10-10  1:50 UTC (permalink / raw)
  To: Laszlo Ersek, edk2-devel@lists.01.org
  Cc: Kinney, Michael D, Wolman, Ayellet, Yao, Jiewen, Dong, Eric,
	Zeng, Star

I have summary in each patch email. I removed the CC of some patches because 
there's no update from v3 to v4. I thought this could remind you of this situation.
What's the recommended way? Keep the CC as-was and just add summaries in 
cover letter?

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Monday, October 09, 2017 11:56 PM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric
> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL
> pointer detection during VBE SHIM installing
> 
> On 10/09/17 17:54, Laszlo Ersek wrote:
> > On 10/09/17 16:17, Jian J Wang wrote:
> >> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
> >> detection is enabled, this driver will fail to load. NULL pointer detection
> >> bypassing code is added to prevent such problem during boot.
> >>
> >> Please note that Windows 7 will try to access VBE SHIM during boot if it's
> >> installed, and then cause boot failure. This can be fixed by setting BIT7
> >> of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
> >> after EndOfDxe. As far as we know, there's no other OSs has such issue.
> >>
> >> Cc: Star Zeng <star.zeng@intel.com>
> >> Cc: Eric Dong <eric.dong@intel.com>
> >> Cc: Jiewen Yao <jiewen.yao@intel.com>
> >> Cc: Michael Kinney <michael.d.kinney@intel.com>
> >> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
> >> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
> >> Contributed-under: TianoCore Contribution Agreement 1.1
> >> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> >> ---
> >>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
> >>  OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
> >>  2 files changed, 15 insertions(+)
> >>
> >> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >> index 577e07b0a8..ff68c99e96 100644
> >> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >> @@ -77,3 +77,4 @@
> >>  [Pcd]
> >>    gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
> >>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
> >> +
> gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
> >> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c
> b/OvmfPkg/QemuVideoDxe/VbeShim.c
> >> index e45a08e887..8ba5522cde 100644
> >> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
> >> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
> >> @@ -75,6 +75,20 @@ InstallVbeShim (
> >>    UINTN                Printed;
> >>    VBE_MODE_INFO        *VbeModeInfo;
> >>
> >> +  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0)
> {
> >> +    DEBUG ((
> >> +      DEBUG_WARN,
> >> +      "%a: page 0 protected, not installing VBE shim\n",
> >> +      __FUNCTION__
> >> +      ));
> >> +    DEBUG ((
> >> +      DEBUG_WARN,
> >> +      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
> >> +      __FUNCTION__
> >> +      ));
> >> +    return;
> >> +  }
> >> +
> >>    Segment0 = 0x00000;
> >>    SegmentC = 0xC0000;
> >>    SegmentF = 0xF0000;
> >>
> >
> > If this patch is entirely identical to the previous version (v3), then
> > you should have please picked up the review tags from Jordan and myself,
> > the ones that you got for v3:
> >
> > http://mid.mail-
> archive.com/150696711831.2454.16712170525103415248@jljusten-skl
> >
> > http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-
> d03b330047cc@redhat.com
> >
> > This way we can quickly filter out already reviewed patches, and avoid
> > re-reviewing when there are no changes.
> >
> >
> > Your cover letter v4 0/6 also does not summarize the changes relative to
> > v3; in the future please don't forget about that.
> 
> ... personal CC's for OvmfPkg maintainers and reviewers are also missing
> from this patch. Please check "Maintainers.txt" every time.
> 
> Thanks
> Laszlo

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-10  1:50       ` Wang, Jian J
@ 2017-10-10  8:13         ` Laszlo Ersek
  2017-10-10  8:41           ` Wang, Jian J
  0 siblings, 1 reply; 15+ messages in thread
From: Laszlo Ersek @ 2017-10-10  8:13 UTC (permalink / raw)
  To: Wang, Jian J, edk2-devel@lists.01.org
  Cc: Kinney, Michael D, Wolman, Ayellet, Yao, Jiewen, Dong, Eric,
	Zeng, Star

On 10/10/17 03:50, Wang, Jian J wrote:
> I have summary in each patch email.

Sure, you have a commit message, but you didn't point out any v3->v4
changes. (If there are no v3->v4 changes, then please pick up the R-b's
received for v3.)

> I removed the CC of some patches because 
> there's no update from v3 to v4. I thought this could remind you of this situation.
> What's the recommended way? Keep the CC as-was and just add summaries in 
> cover letter?

Maintainers should always be CC'd, even if there are no changes relative
to the previous version.

Personally I prefer summarizing the changes in the cover letter, and
also explaining the changes in more detail -- or pointing out the lack
of any changes -- on each individual patch.

If you have a bit of time for reading, I recommend the following wiki
article:

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers

In it, I had written down most everything that I have in mind about the
edk2 development process. The following steps pertain to the current
discussion (i.e., picking up feedback tags, adding Maintainer CC's, and
pointing out changes per patch):

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-18

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-28

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-30

Thanks,
Laszlo


> 
>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Monday, October 09, 2017 11:56 PM
>> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
>> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
>> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric
>> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
>> Subject: Re: [edk2] [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL
>> pointer detection during VBE SHIM installing
>>
>> On 10/09/17 17:54, Laszlo Ersek wrote:
>>> On 10/09/17 16:17, Jian J Wang wrote:
>>>> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
>>>> detection is enabled, this driver will fail to load. NULL pointer detection
>>>> bypassing code is added to prevent such problem during boot.
>>>>
>>>> Please note that Windows 7 will try to access VBE SHIM during boot if it's
>>>> installed, and then cause boot failure. This can be fixed by setting BIT7
>>>> of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
>>>> after EndOfDxe. As far as we know, there's no other OSs has such issue.
>>>>
>>>> Cc: Star Zeng <star.zeng@intel.com>
>>>> Cc: Eric Dong <eric.dong@intel.com>
>>>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>>>> Cc: Michael Kinney <michael.d.kinney@intel.com>
>>>> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
>>>> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
>>>> ---
>>>>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
>>>>  OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
>>>>  2 files changed, 15 insertions(+)
>>>>
>>>> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>> b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>>>> index 577e07b0a8..ff68c99e96 100644
>>>> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>>>> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
>>>> @@ -77,3 +77,4 @@
>>>>  [Pcd]
>>>>    gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
>>>>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
>>>> +
>> gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
>>>> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c
>> b/OvmfPkg/QemuVideoDxe/VbeShim.c
>>>> index e45a08e887..8ba5522cde 100644
>>>> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
>>>> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
>>>> @@ -75,6 +75,20 @@ InstallVbeShim (
>>>>    UINTN                Printed;
>>>>    VBE_MODE_INFO        *VbeModeInfo;
>>>>
>>>> +  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0)
>> {
>>>> +    DEBUG ((
>>>> +      DEBUG_WARN,
>>>> +      "%a: page 0 protected, not installing VBE shim\n",
>>>> +      __FUNCTION__
>>>> +      ));
>>>> +    DEBUG ((
>>>> +      DEBUG_WARN,
>>>> +      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
>>>> +      __FUNCTION__
>>>> +      ));
>>>> +    return;
>>>> +  }
>>>> +
>>>>    Segment0 = 0x00000;
>>>>    SegmentC = 0xC0000;
>>>>    SegmentF = 0xF0000;
>>>>
>>>
>>> If this patch is entirely identical to the previous version (v3), then
>>> you should have please picked up the review tags from Jordan and myself,
>>> the ones that you got for v3:
>>>
>>> http://mid.mail-
>> archive.com/150696711831.2454.16712170525103415248@jljusten-skl
>>>
>>> http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-
>> d03b330047cc@redhat.com
>>>
>>> This way we can quickly filter out already reviewed patches, and avoid
>>> re-reviewing when there are no changes.
>>>
>>>
>>> Your cover letter v4 0/6 also does not summarize the changes relative to
>>> v3; in the future please don't forget about that.
>>
>> ... personal CC's for OvmfPkg maintainers and reviewers are also missing
>> from this patch. Please check "Maintainers.txt" every time.
>>
>> Thanks
>> Laszlo



^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing
  2017-10-10  8:13         ` Laszlo Ersek
@ 2017-10-10  8:41           ` Wang, Jian J
  0 siblings, 0 replies; 15+ messages in thread
From: Wang, Jian J @ 2017-10-10  8:41 UTC (permalink / raw)
  To: Laszlo Ersek, edk2-devel@lists.01.org
  Cc: Kinney, Michael D, Wolman, Ayellet, Yao, Jiewen, Dong, Eric,
	Zeng, Star

Got it. Thank you very much for the advice and information.

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Tuesday, October 10, 2017 4:13 PM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric
> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL
> pointer detection during VBE SHIM installing
> 
> On 10/10/17 03:50, Wang, Jian J wrote:
> > I have summary in each patch email.
> 
> Sure, you have a commit message, but you didn't point out any v3->v4
> changes. (If there are no v3->v4 changes, then please pick up the R-b's
> received for v3.)
> 
> > I removed the CC of some patches because
> > there's no update from v3 to v4. I thought this could remind you of this
> situation.
> > What's the recommended way? Keep the CC as-was and just add summaries in
> > cover letter?
> 
> Maintainers should always be CC'd, even if there are no changes relative
> to the previous version.
> 
> Personally I prefer summarizing the changes in the cover letter, and
> also explaining the changes in more detail -- or pointing out the lack
> of any changes -- on each individual patch.
> 
> If you have a bit of time for reading, I recommend the following wiki
> article:
> 
> https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-
> guide-for-edk2-contributors-and-maintainers
> 
> In it, I had written down most everything that I have in mind about the
> edk2 development process. The following steps pertain to the current
> discussion (i.e., picking up feedback tags, adding Maintainer CC's, and
> pointing out changes per patch):
> 
> https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-
> guide-for-edk2-contributors-and-maintainers#contrib-18
> 
> https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-
> guide-for-edk2-contributors-and-maintainers#contrib-28
> 
> https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-
> guide-for-edk2-contributors-and-maintainers#contrib-30
> 
> Thanks,
> Laszlo
> 
> 
> >
> >> -----Original Message-----
> >> From: Laszlo Ersek [mailto:lersek@redhat.com]
> >> Sent: Monday, October 09, 2017 11:56 PM
> >> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> >> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
> >> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong,
> Eric
> >> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
> >> Subject: Re: [edk2] [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL
> >> pointer detection during VBE SHIM installing
> >>
> >> On 10/09/17 17:54, Laszlo Ersek wrote:
> >>> On 10/09/17 16:17, Jian J Wang wrote:
> >>>> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
> >>>> detection is enabled, this driver will fail to load. NULL pointer detection
> >>>> bypassing code is added to prevent such problem during boot.
> >>>>
> >>>> Please note that Windows 7 will try to access VBE SHIM during boot if it's
> >>>> installed, and then cause boot failure. This can be fixed by setting BIT7
> >>>> of PcdNullPointerDetectionPropertyMask to disable NULL pointer
> detection
> >>>> after EndOfDxe. As far as we know, there's no other OSs has such issue.
> >>>>
> >>>> Cc: Star Zeng <star.zeng@intel.com>
> >>>> Cc: Eric Dong <eric.dong@intel.com>
> >>>> Cc: Jiewen Yao <jiewen.yao@intel.com>
> >>>> Cc: Michael Kinney <michael.d.kinney@intel.com>
> >>>> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
> >>>> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
> >>>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>>> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> >>>> ---
> >>>>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf |  1 +
> >>>>  OvmfPkg/QemuVideoDxe/VbeShim.c        | 14 ++++++++++++++
> >>>>  2 files changed, 15 insertions(+)
> >>>>
> >>>> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >> b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >>>> index 577e07b0a8..ff68c99e96 100644
> >>>> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >>>> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> >>>> @@ -77,3 +77,4 @@
> >>>>  [Pcd]
> >>>>    gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
> >>>>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
> >>>> +
> >> gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
> >>>> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c
> >> b/OvmfPkg/QemuVideoDxe/VbeShim.c
> >>>> index e45a08e887..8ba5522cde 100644
> >>>> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
> >>>> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
> >>>> @@ -75,6 +75,20 @@ InstallVbeShim (
> >>>>    UINTN                Printed;
> >>>>    VBE_MODE_INFO        *VbeModeInfo;
> >>>>
> >>>> +  if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) ==
> BIT0)
> >> {
> >>>> +    DEBUG ((
> >>>> +      DEBUG_WARN,
> >>>> +      "%a: page 0 protected, not installing VBE shim\n",
> >>>> +      __FUNCTION__
> >>>> +      ));
> >>>> +    DEBUG ((
> >>>> +      DEBUG_WARN,
> >>>> +      "%a: page 0 protection prevents Windows 7 from booting anyway\n",
> >>>> +      __FUNCTION__
> >>>> +      ));
> >>>> +    return;
> >>>> +  }
> >>>> +
> >>>>    Segment0 = 0x00000;
> >>>>    SegmentC = 0xC0000;
> >>>>    SegmentF = 0xF0000;
> >>>>
> >>>
> >>> If this patch is entirely identical to the previous version (v3), then
> >>> you should have please picked up the review tags from Jordan and myself,
> >>> the ones that you got for v3:
> >>>
> >>> http://mid.mail-
> >> archive.com/150696711831.2454.16712170525103415248@jljusten-skl
> >>>
> >>> http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-
> >> d03b330047cc@redhat.com
> >>>
> >>> This way we can quickly filter out already reviewed patches, and avoid
> >>> re-reviewing when there are no changes.
> >>>
> >>>
> >>> Your cover letter v4 0/6 also does not summarize the changes relative to
> >>> v3; in the future please don't forget about that.
> >>
> >> ... personal CC's for OvmfPkg maintainers and reviewers are also missing
> >> from this patch. Please check "Maintainers.txt" every time.
> >>
> >> Thanks
> >> Laszlo


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 0/6] Add NULL pointer detection feature
  2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
                   ` (5 preceding siblings ...)
  2017-10-09 14:17 ` [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing Jian J Wang
@ 2017-10-11  0:52 ` Wang, Jian J
  6 siblings, 0 replies; 15+ messages in thread
From: Wang, Jian J @ 2017-10-11  0:52 UTC (permalink / raw)
  To: Wang, Jian J, edk2-devel@lists.01.org
  Cc: Yao, Jiewen, Dong, Eric, Kinney, Michael D, Zeng, Star

Hi,

Any more comments for this version of patch? If no, I'll check in it today. Thanks.

Jian

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Jian J
> Wang
> Sent: Monday, October 09, 2017 10:17 PM
> To: edk2-devel@lists.01.org
> Subject: [edk2] [PATCH v4 0/6] Add NULL pointer detection feature
> 
> The mechanism behind is to trigger a page fault exception at address 0.
> This can be made by disabling page 0 (0-4095) during page table setup.
> So this feature can only be available on platform with paging enabled.
> 
> Once this feature is enabled, any code, like CSM, which has to access
> memory in page 0 needs to enable this page temporarily in advance and
> disable it afterwards.
> 
> PcdNullPointerDetectionPropertyMask is used to control and elaborate
> the use cases. For example, BIT7 of this PCD must be set for Windows 7
> boot on Qemu if BIT0 set; or boot will fail.
> 
> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> 
> Jian J Wang (5):
>   MdeModulePkg/DxeIpl: Implement NULL pointer detection
>   MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for NULL pointer
>     detection
>   UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM
>     code
>   IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection
>   OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM
>     installing
> 
> Wang, Jian J (1):
>   MdeModulePkg/MdeModulePkg.dec,.uni: Add NULL pointer detection PCD
> 
>  .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c       | 101 ++++++++++++++
>  .../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.h       |   2 +
>  .../Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf      |   2 +
>  .../Csm/LegacyBiosDxe/LegacyBda.c                  |   4 +
>  .../Csm/LegacyBiosDxe/LegacyBios.c                 | 152 +++++++++++++++++++++
>  .../Csm/LegacyBiosDxe/LegacyBiosDxe.inf            |   2 +
>  .../Csm/LegacyBiosDxe/LegacyBiosInterface.h        |  18 +++
>  .../Csm/LegacyBiosDxe/LegacyBootSupport.c          |  23 +++-
>  .../Csm/LegacyBiosDxe/LegacyPci.c                  |  17 ++-
>  IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c  |  27 +++-
>  MdeModulePkg/Core/Dxe/DxeMain.inf                  |   1 +
>  MdeModulePkg/Core/Dxe/Mem/Page.c                   |   4 +-
>  MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c      |  65 +++++++++
>  MdeModulePkg/Core/DxeIplPeim/DxeIpl.h              |  25 ++++
>  MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf            |   1 +
>  MdeModulePkg/Core/DxeIplPeim/DxeLoad.c             |   1 +
>  MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c    |  17 ++-
>  MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c     |   4 +
>  MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c   |  93 ++++++++++++-
>  MdeModulePkg/MdeModulePkg.dec                      |  13 ++
>  MdeModulePkg/MdeModulePkg.uni                      |  13 ++
>  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf              |   1 +
>  OvmfPkg/QemuVideoDxe/VbeShim.c                     |  14 ++
>  UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c           |  12 ++
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c              |  25 +++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf       |   1 +
>  UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c            |  12 ++
>  27 files changed, 628 insertions(+), 22 deletions(-)
> 
> --
> 2.14.1.windows.1
> 
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection
  2017-10-09 14:17 ` [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection Jian J Wang
@ 2017-10-11 21:29   ` Laszlo Ersek
  2017-10-12  1:06     ` Wang, Jian J
  0 siblings, 1 reply; 15+ messages in thread
From: Laszlo Ersek @ 2017-10-11 21:29 UTC (permalink / raw)
  To: Jian J Wang, edk2-devel
  Cc: Michael Kinney, Ayellet Wolman, Jiewen Yao, Eric Dong, Star Zeng

This patch breaks the GCC5 build:

On 10/09/17 16:17, Jian J Wang wrote:

> diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> index 3d9a8b9649..f42c13cd89 100644
> --- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> +++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> @@ -57,7 +57,11 @@ LegacyBiosInt86 (
>    IN  EFI_IA32_REGISTER_SET         *Regs
>    )
>  {
> -  UINT32  *VectorBase;
> +  UINT16                Segment;
> +  UINT16                Offset;
> +  LEGACY_BIOS_INSTANCE  *Private;
> +
> +  Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
>  
>    Regs->X.Flags.Reserved1 = 1;
>    Regs->X.Flags.Reserved2 = 0;
> @@ -72,12 +76,15 @@ LegacyBiosInt86 (
>    // The base address of legacy interrupt vector table is 0.
>    // We use this base address to get the legacy interrupt handler.
>    //
> -  VectorBase              = 0;
> +  DisableNullDetection ();
> +  Segment               = (UINT16)(((UINT32 *)0)[BiosInt] >> 16);
> +  Offset                = (UINT16)((UINT32 *)0)[BiosInt];
> +  EnableNullDetection ();
>    
>    return InternalLegacyBiosFarCall (
>             This,
> -           (UINT16) ((VectorBase)[BiosInt] >> 16),
> -           (UINT16) (VectorBase)[BiosInt],
> +           Segment,
> +           Offset,
>             Regs,
>             &Regs->X.Flags,
>             sizeof (Regs->X.Flags)

IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c: In function 'LegacyBiosInt86':
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c:62:26: error: variable 'Private' set but not used [-Werror=unused-but-set-variable]
   LEGACY_BIOS_INSTANCE  *Private;
                          ^~~~~~~
cc1: all warnings being treated as errors

Can you please send a patch?

Thanks!
Laszlo


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection
  2017-10-11 21:29   ` Laszlo Ersek
@ 2017-10-12  1:06     ` Wang, Jian J
  0 siblings, 0 replies; 15+ messages in thread
From: Wang, Jian J @ 2017-10-12  1:06 UTC (permalink / raw)
  To: Laszlo Ersek, edk2-devel@lists.01.org
  Cc: Kinney, Michael D, Wolman, Ayellet, Yao, Jiewen, Dong, Eric,
	Zeng, Star

Thanks for catching this issue. Patch has been sent out. 

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Thursday, October 12, 2017 5:30 AM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric
> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code
> to bypass NULL pointer detection
> 
> This patch breaks the GCC5 build:
> 
> On 10/09/17 16:17, Jian J Wang wrote:
> 
> > diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> > index 3d9a8b9649..f42c13cd89 100644
> > --- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> > +++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
> > @@ -57,7 +57,11 @@ LegacyBiosInt86 (
> >    IN  EFI_IA32_REGISTER_SET         *Regs
> >    )
> >  {
> > -  UINT32  *VectorBase;
> > +  UINT16                Segment;
> > +  UINT16                Offset;
> > +  LEGACY_BIOS_INSTANCE  *Private;
> > +
> > +  Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
> >
> >    Regs->X.Flags.Reserved1 = 1;
> >    Regs->X.Flags.Reserved2 = 0;
> > @@ -72,12 +76,15 @@ LegacyBiosInt86 (
> >    // The base address of legacy interrupt vector table is 0.
> >    // We use this base address to get the legacy interrupt handler.
> >    //
> > -  VectorBase              = 0;
> > +  DisableNullDetection ();
> > +  Segment               = (UINT16)(((UINT32 *)0)[BiosInt] >> 16);
> > +  Offset                = (UINT16)((UINT32 *)0)[BiosInt];
> > +  EnableNullDetection ();
> >
> >    return InternalLegacyBiosFarCall (
> >             This,
> > -           (UINT16) ((VectorBase)[BiosInt] >> 16),
> > -           (UINT16) (VectorBase)[BiosInt],
> > +           Segment,
> > +           Offset,
> >             Regs,
> >             &Regs->X.Flags,
> >             sizeof (Regs->X.Flags)
> 
> IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c: In function
> 'LegacyBiosInt86':
> IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c:62:26: error: variable
> 'Private' set but not used [-Werror=unused-but-set-variable]
>    LEGACY_BIOS_INSTANCE  *Private;
>                           ^~~~~~~
> cc1: all warnings being treated as errors
> 
> Can you please send a patch?
> 
> Thanks!
> Laszlo

^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2017-10-12  1:02 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-10-09 14:17 [PATCH v4 0/6] Add NULL pointer detection feature Jian J Wang
2017-10-09 14:17 ` [PATCH v4 1/6] MdeModulePkg/MdeModulePkg.dec, .uni: Add NULL pointer detection PCD Jian J Wang
2017-10-09 14:17 ` [PATCH v4 2/6] MdeModulePkg/DxeIpl: Implement NULL pointer detection Jian J Wang
2017-10-09 14:17 ` [PATCH v4 3/6] MdeModulePkg/Core/Dxe: Add EndOfDxe workaround for " Jian J Wang
2017-10-09 14:17 ` [PATCH v4 4/6] UefiCpuPkg/PiSmmCpuDxeSmm: Implement NULL pointer detection for SMM code Jian J Wang
2017-10-09 14:17 ` [PATCH v4 5/6] IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection Jian J Wang
2017-10-11 21:29   ` Laszlo Ersek
2017-10-12  1:06     ` Wang, Jian J
2017-10-09 14:17 ` [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing Jian J Wang
2017-10-09 15:54   ` Laszlo Ersek
2017-10-09 15:55     ` Laszlo Ersek
2017-10-10  1:50       ` Wang, Jian J
2017-10-10  8:13         ` Laszlo Ersek
2017-10-10  8:41           ` Wang, Jian J
2017-10-11  0:52 ` [PATCH v4 0/6] Add NULL pointer detection feature Wang, Jian J

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