MdeModulePkg/DxeIpl: Implement NULL pointer detection
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> Reviewed-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
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@@ -115,6 +115,7 @@
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[Pcd.IA32,Pcd.X64]
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gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable ## SOMETIMES_CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask ## CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask ## CONSUMES
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[Pcd.IA32,Pcd.X64,Pcd.ARM,Pcd.AARCH64]
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gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack ## SOMETIMES_CONSUMES
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