Stack guard feature makes use of paging mechanism to monitor if there's a
stack overflow occurred during boot.

This patch will check setting of PCD PcdCpuStackGuard. If it's TRUE, DxeIpl
will setup page table and set the page at which the stack base locates to be
NOT PRESENT. If stack is used up and memory access cross into the last page
of it, #PF exception will be triggered.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@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.inf          |  1 +
 MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c  | 35 ++++++++++++++--
 MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c   |  1 +
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 51 ++++++++++++++++++------
 4 files changed, 71 insertions(+), 17 deletions(-)

diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
index 9d0e76a293..bc857629f8 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
@@ -116,6 +116,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable                      ## SOMETIMES_CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask    ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                       ## CONSUMES
 
 [Pcd.IA32,Pcd.X64,Pcd.ARM,Pcd.AARCH64]
   gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack               ## SOMETIMES_CONSUMES
diff --git a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
index 96f5718444..92f2247bd4 100644
--- a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
@@ -211,6 +211,36 @@ IsExecuteDisableBitAvailable (
   return Available;
 }
 
+/**
+  The function will check if page table should be setup or not.
+
+  @retval TRUE      Page table should be created.
+  @retval FALSE     Page table should not be created.
+**/
+BOOLEAN
+ToBuildPageTable (
+  VOID
+  )
+{
+  if (!IsIa32PaeSupport ()) {
+    return FALSE;
+  }
+
+  if (IsNullDetectionEnabled ()) {
+    return TRUE;
+  }
+
+  if (PcdGetBool (PcdCpuStackGuard)) {
+    return TRUE;
+  }
+
+  if (PcdGetBool (PcdSetNxForStack) && IsExecuteDisableBitAvailable ()) {
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
 /**
    Transfers control to DxeCore.
 
@@ -385,10 +415,7 @@ HandOffToDxeCore (
     TopOfStack = (EFI_PHYSICAL_ADDRESS) (UINTN) ALIGN_POINTER (TopOfStack, CPU_STACK_ALIGNMENT);
 
     PageTables = 0;
-    BuildPageTablesIa32Pae = (BOOLEAN) (IsIa32PaeSupport () &&
-                                        (IsNullDetectionEnabled () ||
-                                         (PcdGetBool (PcdSetNxForStack) &&
-                                          IsExecuteDisableBitAvailable ())));
+    BuildPageTablesIa32Pae = ToBuildPageTable();
     if (BuildPageTablesIa32Pae) {
       PageTables = Create4GPageTablesIa32Pae (BaseOfStack, STACK_SIZE);
       if (IsExecuteDisableBitAvailable ()) {
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
index f613221b81..b75a4489bf 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c
@@ -95,6 +95,7 @@ HandOffToDxeCore (
     // for the DxeIpl and the DxeCore are both X64.
     //
     ASSERT (PcdGetBool (PcdSetNxForStack) == FALSE);
+    ASSERT (PcdGetBool (PcdCpuStackGuard) == FALSE);
   }
   
   //
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 29b6205e88..a2466b7766 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -117,6 +117,39 @@ EnableExecuteDisableBit (
   AsmWriteMsr64 (0xC0000080, MsrRegisters);
 }
 
+/**
+  The function will check if page table entry should be splitted to smaller
+  granularity.
+
+  @retval TRUE      Page table should be created.
+  @retval FALSE     Page table should not be created.
+**/
+BOOLEAN
+ToSplitPageTable (
+  IN EFI_PHYSICAL_ADDRESS               Address,
+  IN UINTN                              Size,
+  IN EFI_PHYSICAL_ADDRESS               StackBase,
+  IN UINTN                              StackSize
+  )
+{
+  if (IsNullDetectionEnabled () && Address == 0) {
+    return TRUE;
+  }
+
+  if (PcdGetBool (PcdCpuStackGuard)) {
+    if (StackBase >= Address && StackBase < (Address + Size)) {
+      return TRUE;
+    }
+  }
+
+  if (PcdGetBool (PcdSetNxForStack)) {
+    if ((Address < StackBase + StackSize) && ((Address + Size) > StackBase)) {
+      return TRUE;
+    }
+  }
+
+  return FALSE;
+}
 /**
   Split 2M page to 4K.
 
@@ -160,7 +193,8 @@ Split2MPageTo4K (
     PageTableEntry->Uint64 = (UINT64) PhysicalAddress4K | AddressEncMask;
     PageTableEntry->Bits.ReadWrite = 1;
 
-    if (IsNullDetectionEnabled () && PhysicalAddress4K == 0) {
+    if ((IsNullDetectionEnabled () && PhysicalAddress4K == 0) ||
+        (PcdGetBool (PcdCpuStackGuard) && PhysicalAddress4K == StackBase)) {
       PageTableEntry->Bits.Present = 0;
     } else {
       PageTableEntry->Bits.Present = 1;
@@ -214,10 +248,7 @@ Split1GPageTo2M (
 
   PhysicalAddress2M = PhysicalAddress;
   for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PhysicalAddress2M += SIZE_2MB) {
-    if ((IsNullDetectionEnabled () && PhysicalAddress2M == 0)
-        || (PcdGetBool (PcdSetNxForStack)
-            && (PhysicalAddress2M < StackBase + StackSize)
-            && ((PhysicalAddress2M + SIZE_2MB) > StackBase))) {
+    if (ToSplitPageTable (PhysicalAddress2M, SIZE_2MB, StackBase, StackSize)) {
       //
       // Need to split this 2M page that covers NULL or stack range.
       //
@@ -359,10 +390,7 @@ CreateIdentityMappingPageTables (
       PageDirectory1GEntry = (VOID *) PageDirectoryPointerEntry;
     
       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectory1GEntry++, PageAddress += SIZE_1GB) {
-        if ((IsNullDetectionEnabled () && PageAddress == 0)
-            || (PcdGetBool (PcdSetNxForStack)
-                && (PageAddress < StackBase + StackSize)
-                && ((PageAddress + SIZE_1GB) > StackBase))) {
+        if (ToSplitPageTable (PageAddress, SIZE_1GB, StackBase, StackSize)) {
           Split1GPageTo2M (PageAddress, (UINT64 *) PageDirectory1GEntry, StackBase, StackSize);
         } else {
           //
@@ -391,10 +419,7 @@ CreateIdentityMappingPageTables (
         PageDirectoryPointerEntry->Bits.Present = 1;
 
         for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += SIZE_2MB) {
-          if ((IsNullDetectionEnabled () && PageAddress == 0)
-              || (PcdGetBool (PcdSetNxForStack)
-                  && (PageAddress < StackBase + StackSize)
-                  && ((PageAddress + SIZE_2MB) > StackBase))) {
+          if (ToSplitPageTable (PageAddress, SIZE_2MB, StackBase, StackSize)) {
             //
             // Need to split this 2M page that covers NULL or stack range.
             //
-- 
2.14.1.windows.1

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