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UefiCpuPkg/PiSmmCpuDxeSmm: patch "gSmmCr4" with PatchInstructionX86()

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Unlike "gSmmCr3" in the previous patch, "gSmmCr4" is not only used for
machine code patching, but also as a means to communicate the initial CR4
value from SmmRelocateBases() to InitSmmS3ResumeState(). In other words,
the last four bytes of the "mov eax, Cr4Value" instruction's binary
representation are utilized as normal data too.

In order to get rid of the DB for "mov eax, Cr4Value", we have to split
both roles, patching and data flow. Introduce the "mSmmCr4" global (SMRAM)
variable for the data flow purpose. Rename the "gSmmCr4" variable to
"gPatchSmmCr4" so that its association with PatchInstructionX86() is clear
from the declaration, change its type to X86_ASSEMBLY_PATCH_LABEL, and
patch it with PatchInstructionX86(), to the value now contained in
"mSmmCr4".

This lets us remove the binary (DB) encoding of "mov eax, Cr4Value" in
"SmmInit.nasm".

Cc: Eric Dong <eric.dong@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=866
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
This commit is contained in:
Laszlo Ersek
2018-02-02 02:10:05 +01:00
parent 6b0841c166
commit 351b49c1a7
5 changed files with 16 additions and 9 deletions
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3
UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
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@@ -310,7 +310,8 @@ extern CONST UINT8 gcSmmInitTemplate[];
extern CONST UINT16 gcSmmInitSize;
extern UINT32 gSmmCr0;
X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr3;
extern UINT32 gSmmCr4;
extern UINT32 mSmmCr4;
X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr4;
extern UINTN gSmmInitStack;
/**