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
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