UefiCpuPkg/CpuDxe: implement non-stop mode for uefi

Same as SMM profile feature, a special #PF is used to set page attribute
to 'present' and a special #DB handler to reset it back to 'not-present',
right after the instruction causing #PF got executed.

Since the new #PF handler won't enter into dead-loop, the instruction
which caused the #PF will get chance to re-execute with accessible pages.

The exception message will still be printed out on debug console so that
the developer/QA can find that there's potential heap overflow or null
pointer access occurred.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>

1 files changed, 167 insertions, 0 deletions

diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c b/UefiCpuPkg/CpuDxe/CpuPageTable.c
index df021798c0..97257fbe48 100644
--- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
+++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
@@ -22,6 +22,10 @@
 #include <Library/MemoryAllocationLib.h>

 #include <Library/DebugLib.h>

 #include <Library/UefiBootServicesTableLib.h>

+#include <Library/PeCoffGetEntryPointLib.h>

+#include <Library/SerialPortLib.h>

+#include <Library/SynchronizationLib.h>

+#include <Library/PrintLib.h>

 #include <Protocol/MpService.h>

 #include <Protocol/SmmBase2.h>

 #include <Register/Cpuid.h>

@@ -73,6 +77,10 @@
 #define PAGING_2M_ADDRESS_MASK_64 0x000FFFFFFFE00000ull

 #define PAGING_1G_ADDRESS_MASK_64 0x000FFFFFC0000000ull

 

+#define MAX_PF_ENTRY_COUNT        10

+#define MAX_DEBUG_MESSAGE_LENGTH  0x100

+#define IA32_PF_EC_ID             BIT4

+

 typedef enum {

   PageNone,

   Page4K,

@@ -102,6 +110,12 @@ PAGE_TABLE_POOL                   *mPageTablePool = NULL;
 PAGE_TABLE_LIB_PAGING_CONTEXT     mPagingContext;

 EFI_SMM_BASE2_PROTOCOL            *mSmmBase2 = NULL;

 

+//

+// Record the page fault exception count for one instruction execution.

+//

+UINTN                     *mPFEntryCount;

+UINT64                    *(*mLastPFEntryPointer)[MAX_PF_ENTRY_COUNT];

+

 /**

  Check if current execution environment is in SMM mode or not, via

  EFI_SMM_BASE2_PROTOCOL.

@@ -1136,6 +1150,150 @@ AllocatePageTableMemory (
 }

 

 /**

+  Special handler for #DB exception, which will restore the page attributes

+  (not-present). It should work with #PF handler which will set pages to

+  'present'.

+

+  @param ExceptionType  Exception type.

+  @param SystemContext  Pointer to EFI_SYSTEM_CONTEXT.

+

+**/

+VOID

+EFIAPI

+DebugExceptionHandler (

+  IN EFI_EXCEPTION_TYPE   ExceptionType,

+  IN EFI_SYSTEM_CONTEXT   SystemContext

+  )

+{

+  UINTN     CpuIndex;

+  UINTN     PFEntry;

+  BOOLEAN   IsWpEnabled;

+

+  MpInitLibWhoAmI (&CpuIndex);

+

+  //

+  // Clear last PF entries

+  //

+  IsWpEnabled = IsReadOnlyPageWriteProtected ();

+  if (IsWpEnabled) {

+    DisableReadOnlyPageWriteProtect ();

+  }

+

+  for (PFEntry = 0; PFEntry < mPFEntryCount[CpuIndex]; PFEntry++) {

+    if (mLastPFEntryPointer[CpuIndex][PFEntry] != NULL) {

+      *mLastPFEntryPointer[CpuIndex][PFEntry] &= ~IA32_PG_P;

+    }

+  }

+

+  if (IsWpEnabled) {

+    EnableReadOnlyPageWriteProtect ();

+  }

+

+  //

+  // Reset page fault exception count for next page fault.

+  //

+  mPFEntryCount[CpuIndex] = 0;

+

+  //

+  // Flush TLB

+  //

+  CpuFlushTlb ();

+

+  //

+  // Clear TF in EFLAGS

+  //

+  if (mPagingContext.MachineType == IMAGE_FILE_MACHINE_I386) {

+    SystemContext.SystemContextIa32->Eflags &= (UINT32)~BIT8;

+  } else {

+    SystemContext.SystemContextX64->Rflags &= (UINT64)~BIT8;

+  }

+}

+

+/**

+  Special handler for #PF exception, which will set the pages which caused

+  #PF to be 'present'. The attribute of those pages should be restored in

+  the subsequent #DB handler.

+

+  @param ExceptionType  Exception type.

+  @param SystemContext  Pointer to EFI_SYSTEM_CONTEXT.

+

+**/

+VOID

+EFIAPI

+PageFaultExceptionHandler (

+  IN EFI_EXCEPTION_TYPE   ExceptionType,

+  IN EFI_SYSTEM_CONTEXT   SystemContext

+  )

+{

+  EFI_STATUS                      Status;

+  UINT64                          PFAddress;

+  PAGE_TABLE_LIB_PAGING_CONTEXT   PagingContext;

+  PAGE_ATTRIBUTE                  PageAttribute;

+  UINT64                          Attributes;

+  UINT64                          *PageEntry;

+  UINTN                           Index;

+  UINTN                           CpuIndex;

+  UINTN                           PageNumber;

+  BOOLEAN                         NonStopMode;

+

+  PFAddress = AsmReadCr2 () & ~EFI_PAGE_MASK;

+  if (PFAddress < BASE_4KB) {

+    NonStopMode = NULL_DETECTION_NONSTOP_MODE ? TRUE : FALSE;

+  } else {

+    NonStopMode = HEAP_GUARD_NONSTOP_MODE ? TRUE : FALSE;

+  }

+

+  if (NonStopMode) {

+    MpInitLibWhoAmI (&CpuIndex);

+    GetCurrentPagingContext (&PagingContext);

+    //

+    // Memory operation cross page boundary, like "rep mov" instruction, will

+    // cause infinite loop between this and Debug Trap handler. We have to make

+    // sure that current page and the page followed are both in PRESENT state.

+    //

+    PageNumber = 2;

+    while (PageNumber > 0) {

+      PageEntry = GetPageTableEntry (&PagingContext, PFAddress, &PageAttribute);

+      ASSERT(PageEntry != NULL);

+

+      if (PageEntry != NULL) {

+        Attributes = GetAttributesFromPageEntry (PageEntry);

+        if ((Attributes & EFI_MEMORY_RP) != 0) {

+          Attributes &= ~EFI_MEMORY_RP;

+          Status = AssignMemoryPageAttributes (&PagingContext, PFAddress,

+                                               EFI_PAGE_SIZE, Attributes, NULL);

+          if (!EFI_ERROR(Status)) {

+            Index = mPFEntryCount[CpuIndex];

+            //

+            // Re-retrieve page entry because above calling might update page

+            // table due to table split.

+            //

+            PageEntry = GetPageTableEntry (&PagingContext, PFAddress, &PageAttribute);

+            mLastPFEntryPointer[CpuIndex][Index++] = PageEntry;

+            mPFEntryCount[CpuIndex] = Index;

+          }

+        }

+      }

+

+      PFAddress += EFI_PAGE_SIZE;

+      --PageNumber;

+    }

+  }

+

+  //

+  // Initialize the serial port before dumping.

+  //

+  SerialPortInitialize ();

+  //

+  // Display ExceptionType, CPU information and Image information

+  //

+  DumpCpuContext (ExceptionType, SystemContext);

+  if (!NonStopMode) {

+    CpuDeadLoop ();

+  }

+}

+

+/**

   Initialize the Page Table lib.

 **/

 VOID

@@ -1158,6 +1316,15 @@ InitializePageTableLib (
     EnableReadOnlyPageWriteProtect ();

   }

 

+  if (HEAP_GUARD_NONSTOP_MODE || NULL_DETECTION_NONSTOP_MODE) {

+    mPFEntryCount = (UINTN *)AllocateZeroPool (sizeof (UINTN) * mNumberOfProcessors);

+    ASSERT (mPFEntryCount != NULL);

+

+    mLastPFEntryPointer = (UINT64 *(*)[MAX_PF_ENTRY_COUNT])

+                          AllocateZeroPool (sizeof (mLastPFEntryPointer[0]) * mNumberOfProcessors);

+    ASSERT (mLastPFEntryPointer != NULL);

+  }

+

   DEBUG ((DEBUG_INFO, "CurrentPagingContext:\n", CurrentPagingContext.MachineType));

   DEBUG ((DEBUG_INFO, "  MachineType   - 0x%x\n", CurrentPagingContext.MachineType));

   DEBUG ((DEBUG_INFO, "  PageTableBase - 0x%x\n", CurrentPagingContext.ContextData.X64.PageTableBase));